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Sample records for temporal dynamics temperamental

  1. Amygdala temporal dynamics: temperamental differences in the timing of amygdala response to familiar and novel faces

    Directory of Open Access Journals (Sweden)

    Shelton Richard C

    2009-12-01

    Full Text Available Abstract Background Inhibited temperament - the predisposition to respond to new people, places or things with wariness or avoidance behaviors - is associated with increased risk for social anxiety disorder and major depression. Although the magnitude of the amygdala's response to novelty has been identified as a neural substrate of inhibited temperament, there may also be differences in temporal dynamics (latency, duration, and peak. We hypothesized that persons with inhibited temperament would have faster responses to novel relative to familiar neutral faces compared to persons with uninhibited temperament. We used event-related functional magnetic resonance imaging to measure the temporal dynamics of the blood oxygen level dependent (BOLD response to both novel and familiar neutral faces in participants with inhibited or uninhibited temperament. Results Inhibited participants had faster amygdala responses to novel compared with familiar faces, and both longer and greater amygdala response to all faces. There were no differences in peak response. Conclusion Faster amygdala response to novelty may reflect a computational bias that leads to greater neophobic responses and represents a mechanism for the development of social anxiety.

  2. Temperamental predictors of subjective well-being from early adolescence to mid-life: The role of temporal and energetic regulation.

    Science.gov (United States)

    Bojanowska, Agnieszka; Zalewska, Anna M

    2017-02-14

    We investigated links between temperament traits described in Strelau's Regulative Theory of Temperament (Emotional Reactivity, Briskness, Activity, Endurance, Perseveration and Sensory Sensitivity) and subjective well-being (SWB)-Positive Affect, Negative Affect and Life Satisfaction as conceptualised by Diener. Participants representing early (n = 166) and late adolescence (n = 199), early (n = 195) and mid-adulthood (n = 156) filled out Formal Characteristics of Behaviour-Temperament Inventory, Positive and Negative Affect Schedule and Satisfaction with Life Scale. Results showed that higher Briskness, Endurance, Activity, lower Perseveration and Emotional Reactivity corresponded with higher SWB. They predicted 16% of affective components' and 7% of satisfaction variance. Each well-being component had a unique set of predictors; however, predictors of affective components varied across age groups. Higher Positive Affect was predicted by traits responsible for energetic regulation (higher Endurance and Activity and lower Emotional Reactivity) and by higher Perseveration, but their role (excluding Emotional Reactivity) was age-dependent. Higher Negative Affect was predicted by higher Emotional Reactivity and dimensions expressing temporal characteristics, lower Briskness and higher Perseveration (Perseveration was not significant among younger adolescents). Higher Satisfaction was steadily predicted by lower Emotional Reactivity and higher Activity. To conclude, the functions of temperament traits are mostly in line with theoretical expectations, but more complex than indicated by previous research. © 2017 The Authors. International Journal of Psychology published by John Wiley & Sons Ltd on behalf of International Union of Psychological Science.

  3. Temporal dynamics of online petitions.

    Science.gov (United States)

    Böttcher, Lucas; Woolley-Meza, Olivia; Brockmann, Dirk

    2017-01-01

    Online petitions are an important avenue for direct political action, yet the dynamics that determine when a petition will be successful are not well understood. Here we analyze the temporal characteristics of online-petition signing behavior in order to identify systematic differences between popular petitions, which receive a high volume of signatures, and unpopular ones. We find that, in line with other temporal characterizations of human activity, the signing process is typically non-Poissonian and non-homogeneous in time. However, this process exhibits anomalously high memory for human activity, possibly indicating that synchronized external influence or contagion play and important role. More interestingly, we find clear differences in the characteristics of the inter-event time distributions depending on the total number of signatures that petitions receive, independently of the total duration of the petitions. Specifically, popular petitions that attract a large volume of signatures exhibit more variance in the distribution of inter-event times than unpopular petitions with only a few signatures, which could be considered an indication that the former are more bursty. However, petitions with large signature volume are less bursty according to measures that consider the time ordering of inter-event times. Our results, therefore, emphasize the importance of accounting for time ordering to characterize human activity.

  4. The temporal dynamics of speeded decision making

    NARCIS (Netherlands)

    Dutilh, G.

    2012-01-01

    This dissertation sheds light on the temporal dynamics of behavior in speeded decision making. Participants on reaction time (RT) tasks learn, get distracted, speed up, slow down, get confused, get bored, and eventually may start guessing. One can safely say that participants' behavior is dynamic.

  5. Temporal fidelity in dynamic social networks

    DEFF Research Database (Denmark)

    Stopczynski, Arkadiusz; Sapiezynski, Piotr; Pentland, Alex ‘Sandy’

    2015-01-01

    of the network dynamics can be used to inform the process of measuring social networks. The details of measurement are of particular importance when considering dynamic processes where minute-to-minute details are important, because collection of physical proximity interactions with high temporal resolution...

  6. Memory for temporally dynamic scenes.

    Science.gov (United States)

    Ferguson, Ryan; Homa, Donald; Ellis, Derek

    2017-07-01

    Recognition memory was investigated for individual frames extracted from temporally continuous, visually rich film segments of 5-15 min. Participants viewed a short clip from a film in either a coherent or a jumbled order, followed by a recognition test of studied frames. Foils came either from an earlier or a later part of the film (Experiment 1) or from deleted segments selected from random cuts of varying duration (0.5 to 30 s) within the film itself (Experiment 2). When the foils came from an earlier or later part of the film (Experiment 1), recognition was excellent, with the hit rate far exceeding the false-alarm rate (.78 vs. 18). In Experiment 2, recognition was far worse, with the hit rate (.76) exceeding the false-alarm rate only for foils drawn from the longest cuts (15 and 30 s) and matching the false-alarm rate for the 5 s segments. When the foils were drawn from the briefest cuts (0.5 and 1.0 s), the false-alarm rate exceeded the hit rate. Unexpectedly, jumbling had no effect on recognition in either experiment. These results are consistent with the view that memory for complex visually temporal events is excellent, with the integrity unperturbed by disruption of the global structure of the visual stream. Disruption of memory was observed only when foils were drawn from embedded segments of duration less than 5 s, an outcome consistent with the view that memory at these shortest durations are consolidated with expectations drawn from the previous stream.

  7. Dynamic perfusion patterns in temporal lobe epilepsy

    International Nuclear Information System (INIS)

    Dupont, Patrick; Paesschen, Wim van; Zaknun, John J.; Maes, Alex; Tepmongkol, Supatporn; Locharernkul, Chaichon; Vasquez, Silvia; Carpintiero, Silvina; Bal, C.S.; Dondi, Maurizio

    2009-01-01

    To investigate dynamic ictal perfusion changes during temporal lobe epilepsy (TLE). We investigated 37 patients with TLE by ictal and interictal SPECT. All ictal injections were performed within 60 s of seizure onset. Statistical parametric mapping was used to analyse brain perfusion changes and temporal relationships with injection time and seizure duration as covariates. The analysis revealed significant ictal hyperperfusion in the ipsilateral temporal lobe extending to subcortical regions. Hypoperfusion was observed in large extratemporal areas. There were also significant dynamic changes in several extratemporal regions: ipsilateral orbitofrontal and bilateral superior frontal gyri and the contralateral cerebellum and ipsilateral striatum. The study demonstrated early dynamic perfusion changes in extratemporal regions probably involved in both propagation of epileptic activity and initiation of inhibitory mechanisms. (orig.)

  8. Dynamic perfusion patterns in temporal lobe epilepsy

    Energy Technology Data Exchange (ETDEWEB)

    Dupont, Patrick; Paesschen, Wim van [KU Leuven/UZ Gasthuisberg, Nuclear Medicine, Medical Imaging Center and Neurology, Leuven (Belgium); Zaknun, John J. [International Atomic Energy Agency (IAEA), Nuclear Medicine Section, Division of Human Health, Wagramer Strasse 5, PO BOX 200, Vienna (Austria); University Hospital of Innsbruck, Department of Nuclear Medicine, Innsbruck (Austria); Maes, Alex [KU Leuven/UZ Gasthuisberg, Nuclear Medicine, Medical Imaging Center and Neurology, Leuven (Belgium); AZ Groeninge, Nuclear Medicine, Kortrijk (Belgium); Tepmongkol, Supatporn; Locharernkul, Chaichon [Chulalongkorn University, Nuclear Medicine and Neurology, Bangkok (Thailand); Vasquez, Silvia; Carpintiero, Silvina [Fleni Instituto de Investigaciones Neurologicas, Nuclear Medicine, Buenos Aires (Argentina); Bal, C.S. [All India Institute of Medical Sciences, Nuclear Medicine, New Delhi (India); Dondi, Maurizio [International Atomic Energy Agency (IAEA), Nuclear Medicine Section, Division of Human Health, Wagramer Strasse 5, PO BOX 200, Vienna (Austria); Ospedale Maggiore, Nuclear Medicine, Bologna (Italy)

    2009-05-15

    To investigate dynamic ictal perfusion changes during temporal lobe epilepsy (TLE). We investigated 37 patients with TLE by ictal and interictal SPECT. All ictal injections were performed within 60 s of seizure onset. Statistical parametric mapping was used to analyse brain perfusion changes and temporal relationships with injection time and seizure duration as covariates. The analysis revealed significant ictal hyperperfusion in the ipsilateral temporal lobe extending to subcortical regions. Hypoperfusion was observed in large extratemporal areas. There were also significant dynamic changes in several extratemporal regions: ipsilateral orbitofrontal and bilateral superior frontal gyri and the contralateral cerebellum and ipsilateral striatum. The study demonstrated early dynamic perfusion changes in extratemporal regions probably involved in both propagation of epileptic activity and initiation of inhibitory mechanisms. (orig.)

  9. Temperamental Traits Versus Individual Physical Fitness Components and a Physical Activity Level

    Directory of Open Access Journals (Sweden)

    Bernatowicz Dominik

    2015-06-01

    Full Text Available The main aim of the study was to examine whether relationships exist between particular temperamental traits within the concept of Regulative Theory of Temperament and components of physical fitness, that are most crucial for success in sport. The research involved 108 individuals including 63 men (age 21.1 ± 1.6 yrs and 45 women (age 20.7 ± 1.3 yrs. None of the respondents were professionally engaged in sport. Components of physical fitness included: aerobic capacity, strength, agility, static-dynamic balance and reaction time. The respondents also completed two questionnaires: the Formal Characteristics of Behaviour – Temperament Inventory and the International Physical Activity Questionnaire. The results indicate that the temperamental traits had average to poor correlations with the components of physical fitness, whereas more statistically significant correlations were observed in women. Negative correlations were obtained between emotional reactivity and agility, which was a result confirmed by previous research. All temperamental traits related with the energetic aspects of behaviour correlated with simple reaction time in women. Physical activity and aerobic capacity did not correlate with any of the studied traits. The results do not allow for any general conclusions to be drawn, but can serve as a reference point for future research on temperamental traits as delineated by Regulative Theory of Temperament and their relationship with the components of physical fitness.

  10. Temporal dynamics of divided spatial attention.

    Science.gov (United States)

    Itthipuripat, Sirawaj; Garcia, Javier O; Serences, John T

    2013-05-01

    In naturalistic settings, observers often have to monitor multiple objects dispersed throughout the visual scene. However, the degree to which spatial attention can be divided across spatially noncontiguous objects has long been debated, particularly when those objects are in close proximity. Moreover, the temporal dynamics of divided attention are unclear: is the process of dividing spatial attention gradual and continuous, or does it onset in a discrete manner? To address these issues, we recorded steady-state visual evoked potentials (SSVEPs) as subjects covertly monitored two flickering targets while ignoring an intervening distractor that flickered at a different frequency. All three stimuli were clustered within either the lower left or the lower right quadrant, and our dependent measure was SSVEP power at the target and distractor frequencies measured over time. In two experiments, we observed a temporally discrete increase in power for target- vs. distractor-evoked SSVEPs extending from ∼350 to 150 ms prior to correct (but not incorrect) responses. The divergence in SSVEP power immediately prior to a correct response suggests that spatial attention can be divided across noncontiguous locations, even when the targets are closely spaced within a single quadrant. In addition, the division of spatial attention appears to be relatively discrete, as opposed to slow and continuous. Finally, the predictive relationship between SSVEP power and behavior demonstrates that these neurophysiological measures of divided attention are meaningfully related to cognitive function.

  11. Temporal information encoding in dynamic memristive devices

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Wen; Chen, Lin; Du, Chao; Lu, Wei D., E-mail: wluee@eecs.umich.edu [Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, Michigan 48109 (United States)

    2015-11-09

    We show temporal and frequency information can be effectively encoded in memristive devices with inherent short-term dynamics. Ag/Ag{sub 2}S/Pd based memristive devices with low programming voltage (∼100 mV) were fabricated and tested. At weak programming conditions, the devices exhibit inherent decay due to spontaneous diffusion of the Ag atoms. When the devices were subjected to pulse train inputs emulating different spiking patterns, the switching probability distribution function diverges from the standard Poisson distribution and evolves according to the input pattern. The experimentally observed switching probability distributions and the associated cumulative probability functions can be well-explained using a model accounting for the short-term decay effects. Such devices offer an intriguing opportunity to directly encode neural signals for neural information storage and analysis.

  12. Noise-induced temporal dynamics in Turing systems

    KAUST Repository

    Schumacher, Linus J.; Woolley, Thomas E.; Baker, Ruth E.

    2013-01-01

    We examine the ability of intrinsic noise to produce complex temporal dynamics in Turing pattern formation systems, with particular emphasis on the Schnakenberg kinetics. Using power spectral methods, we characterize the behavior of the system using

  13. Identify Dynamic Network Modules with Temporal and Spatial Constraints

    Energy Technology Data Exchange (ETDEWEB)

    Jin, R; McCallen, S; Liu, C; Almaas, E; Zhou, X J

    2007-09-24

    Despite the rapid accumulation of systems-level biological data, understanding the dynamic nature of cellular activity remains a difficult task. The reason is that most biological data are static, or only correspond to snapshots of cellular activity. In this study, we explicitly attempt to detangle the temporal complexity of biological networks by using compilations of time-series gene expression profiling data.We define a dynamic network module to be a set of proteins satisfying two conditions: (1) they form a connected component in the protein-protein interaction (PPI) network; and (2) their expression profiles form certain structures in the temporal domain. We develop the first efficient mining algorithm to discover dynamic modules in a temporal network, as well as frequently occurring dynamic modules across many temporal networks. Using yeast as a model system, we demonstrate that the majority of the identified dynamic modules are functionally homogeneous. Additionally, many of them provide insight into the sequential ordering of molecular events in cellular systems. We further demonstrate that identifying frequent dynamic network modules can significantly increase the signal to noise separation, despite the fact that most dynamic network modules are highly condition-specific. Finally, we note that the applicability of our algorithm is not limited to the study of PPI systems, instead it is generally applicable to the combination of any type of network and time-series data.

  14. Dynamic CRM occupancy reflects a temporal map of developmental progression.

    Science.gov (United States)

    Wilczyński, Bartek; Furlong, Eileen E M

    2010-06-22

    Development is driven by tightly coordinated spatio-temporal patterns of gene expression, which are initiated through the action of transcription factors (TFs) binding to cis-regulatory modules (CRMs). Although many studies have investigated how spatial patterns arise, precise temporal control of gene expression is less well understood. Here, we show that dynamic changes in the timing of CRM occupancy is a prevalent feature common to all TFs examined in a developmental ChIP time course to date. CRMs exhibit complex binding patterns that cannot be explained by the sequence motifs or expression of the TFs themselves. The temporal changes in TF binding are highly correlated with dynamic patterns of target gene expression, which in turn reflect transitions in cellular function during different stages of development. Thus, it is not only the timing of a TF's expression, but also its temporal occupancy in refined time windows, which determines temporal gene expression. Systematic measurement of dynamic CRM occupancy may therefore serve as a powerful method to decode dynamic changes in gene expression driving developmental progression.

  15. Temporal dynamics of Bose-condensed gases

    Energy Technology Data Exchange (ETDEWEB)

    Trujillo Martinez, Mauricio

    2014-03-19

    We perform a detailed quantum dynamical study of non-equilibrium trapped, interacting Bose-condensed gases. We investigate Josephson oscillations between interacting Bose-Einstein condensates confined in a finite size double-well trap and the non-trivial time evolution of a coherent state placed at the center of a two dimensional optical lattice. For the Josephson oscillations three time scales appear. We find that Josephson junction can sustain multiple undamped oscillations up to a characteristic time scale τ{sub c} without exciting atoms out of the condensates. Beyond the characteristic time scale τ{sub c} the dynamics of the junction are governed by fast, non-condensed particles assisted Josephson tunnelling as well as the collisions between non-condensed particles. In the non-condensed particles dominated regime we observe strong damping of the oscillations due to inelastic collisions, equilibrating the system leading to an effective loss of details of the initial conditions. In addition, we predict that an initially self-trapped BEC state will be destroyed by these fast dynamics. The time evolution of a coherent state released at the center of a two dimensional optical lattice shows a ballistic expansion with a decreasing expansion velocity for increasing two-body interactions strength and particle number. Additionally, we predict that if the two-body interactions strength exceeds a certain value, a forerunner splits up from the expanding coherent state. We also observe that this system, which is prepared far from equilibrium, can evolve to a quasistationary non-equilibrium state.

  16. Familial and Temperamental Risk Factors for Social Anxiety Disorder

    Science.gov (United States)

    Hirshfeld-Becker, Dina R.

    2010-01-01

    Social anxiety disorder (SAD) is a common disorder that can lead to significant impairment. In this chapter, the author provides background on the disorder and reviews hypothesized familial and temperamental risk factors. In particular, it highlights the Massachusetts General Hospital (MGH) Longitudinal Study of Children at Risk for Anxiety, now…

  17. Effects of dynamic-range compression on temporal acuity

    DEFF Research Database (Denmark)

    Wiinberg, Alan; Jepsen, Morten Løve; Epp, Bastian

    2016-01-01

    Some of the challenges that hearing-aid listeners experience with speech perception in complex acoustic environments may originate from limitations in the temporal processing of sounds. To systematically investigate the influence of hearing impairment and hearing-aid signal processing on temporal...... processing, temporal modulation transfer functions (TMTFs) and “supra-threshold” modulation-depth discrimination (MDD) thresholds were obtained in normal-hearing (NH) and hearing-impaired (HI) listeners with and without wide-dynamic range compression (WDRC). The TMTFs were obtained using tonal carriers of 1...... with the physical compression of the modulation depth due to the WDRC. Indications of reduced temporal resolution in the HI listeners were observed in the TMTF patterns for the 5 kHz carrier. Significantly higher MDD thresholds were found for the HI group relative to the NH group. No relationship was found between...

  18. Temporal nonlinear beam dynamics in infiltrated photonic crystal fibers

    DEFF Research Database (Denmark)

    Bennet, Francis; Rosberg, Christian Romer; Neshev, Dragomir N.

    Liquid-infiltrated photonic crystal fibers (PCFs) offer a new way of studying light propagation in periodic and discrete systems. A wide range of available fiber structures combined with the ease of infiltration opens up a range of novel experimental opportunities for optical detection and bio...... the evolution of the fiber output beam in the few micro or milliseconds after the beam is turned on. The characterization of the temporal behavior of the thermal nonlinear response provides important information about the nonlocality associated with heat diffusion inside the fiber, thus enabling studies of long...... and technological potential of liquid-infiltrated PCFs it is important to understand the temporal dynamics of nonlinear beam propagation in such structures. In this work we consider thermally induced spatial nonlinear effects in infiltrated photonic crystal fibers. We experimentally study the temporal dynamics...

  19. Spatial and temporal dynamics of land use pattern response to ...

    African Journals Online (AJOL)

    Urban settlements account for only two percent of the Earth's land surface. However, over half of the world's population resides in cities (United Nations, 2001). The quantitative evidences presented here showed that there were drastic changes in the temporal and spatial dynamics of land use/land cover. As an overall ...

  20. Analysing the temporal dynamics of model performance for hydrological models

    NARCIS (Netherlands)

    Reusser, D.E.; Blume, T.; Schaefli, B.; Zehe, E.

    2009-01-01

    The temporal dynamics of hydrological model performance gives insights into errors that cannot be obtained from global performance measures assigning a single number to the fit of a simulated time series to an observed reference series. These errors can include errors in data, model parameters, or

  1. Temporal dynamics of the Saccharopolyspora erythraea phosphoproteome.

    Science.gov (United States)

    Licona-Cassani, Cuauhtemoc; Lim, Sooa; Marcellin, Esteban; Nielsen, Lars K

    2014-05-01

    Actinomycetes undergo a dramatic reorganization of metabolic and cellular machinery during a brief period of growth arrest ("metabolic switch") preceding mycelia differentiation and the onset of secondary metabolite biosynthesis. This study explores the role of phosphorylation in coordinating the metabolic switch in the industrial actinomycete Saccharopolyspora erythraea. A total of 109 phosphopeptides from 88 proteins were detected across a 150-h fermentation using open-profile two-dimensional LC-MS proteomics and TiO(2) enrichment. Quantitative analysis of the phosphopeptides and their unphosphorylated cognates was possible for 20 pairs that also displayed constant total protein expression. Enzymes from central carbon metabolism such as putative acetyl-coenzyme A carboxylase, isocitrate lyase, and 2-oxoglutarate dehydrogenase changed dramatically in the degree of phosphorylation during the stationary phase, suggesting metabolic rearrangement for the reutilization of substrates and the production of polyketide precursors. In addition, an enzyme involved in cellular response to environmental stress, trypsin-like serine protease (SACE_6340/NC_009142_6216), decreased in phosphorylation during the growth arrest stage. More important, enzymes related to the regulation of protein synthesis underwent rapid phosphorylation changes during this stage. Whereas the degree of phosphorylation of ribonuclease Rne/Rng (SACE_1406/NC_009142_1388) increased during the metabolic switch, that of two ribosomal proteins, S6 (SACE_7351/NC_009142_7233) and S32 (SACE_6101/NC_009142_5981), dramatically decreased during this stage of the fermentation, supporting the hypothesis that ribosome subpopulations differentially regulate translation before and after the metabolic switch. Overall, we show the great potential of phosphoproteomic studies to explain microbial physiology and specifically provide evidence of dynamic protein phosphorylation events across the developmental cycle of

  2. Temporal Dynamics of the Saccharopolyspora erythraea Phosphoproteome*

    Science.gov (United States)

    Licona-Cassani, Cuauhtemoc; Lim, SooA; Marcellin, Esteban; Nielsen, Lars K.

    2014-01-01

    Actinomycetes undergo a dramatic reorganization of metabolic and cellular machinery during a brief period of growth arrest (“metabolic switch”) preceding mycelia differentiation and the onset of secondary metabolite biosynthesis. This study explores the role of phosphorylation in coordinating the metabolic switch in the industrial actinomycete Saccharopolyspora erythraea. A total of 109 phosphopeptides from 88 proteins were detected across a 150-h fermentation using open-profile two-dimensional LC-MS proteomics and TiO2 enrichment. Quantitative analysis of the phosphopeptides and their unphosphorylated cognates was possible for 20 pairs that also displayed constant total protein expression. Enzymes from central carbon metabolism such as putative acetyl-coenzyme A carboxylase, isocitrate lyase, and 2-oxoglutarate dehydrogenase changed dramatically in the degree of phosphorylation during the stationary phase, suggesting metabolic rearrangement for the reutilization of substrates and the production of polyketide precursors. In addition, an enzyme involved in cellular response to environmental stress, trypsin-like serine protease (SACE_6340/NC_009142_6216), decreased in phosphorylation during the growth arrest stage. More important, enzymes related to the regulation of protein synthesis underwent rapid phosphorylation changes during this stage. Whereas the degree of phosphorylation of ribonuclease Rne/Rng (SACE_1406/NC_009142_1388) increased during the metabolic switch, that of two ribosomal proteins, S6 (SACE_7351/NC_009142_7233) and S32 (SACE_6101/NC_009142_5981), dramatically decreased during this stage of the fermentation, supporting the hypothesis that ribosome subpopulations differentially regulate translation before and after the metabolic switch. Overall, we show the great potential of phosphoproteomic studies to explain microbial physiology and specifically provide evidence of dynamic protein phosphorylation events across the developmental cycle of

  3. Concurrency-Induced Transitions in Epidemic Dynamics on Temporal Networks.

    Science.gov (United States)

    Onaga, Tomokatsu; Gleeson, James P; Masuda, Naoki

    2017-09-08

    Social contact networks underlying epidemic processes in humans and animals are highly dynamic. The spreading of infections on such temporal networks can differ dramatically from spreading on static networks. We theoretically investigate the effects of concurrency, the number of neighbors that a node has at a given time point, on the epidemic threshold in the stochastic susceptible-infected-susceptible dynamics on temporal network models. We show that network dynamics can suppress epidemics (i.e., yield a higher epidemic threshold) when the node's concurrency is low, but can also enhance epidemics when the concurrency is high. We analytically determine different phases of this concurrency-induced transition, and confirm our results with numerical simulations.

  4. Concurrency-Induced Transitions in Epidemic Dynamics on Temporal Networks

    Science.gov (United States)

    Onaga, Tomokatsu; Gleeson, James P.; Masuda, Naoki

    2017-09-01

    Social contact networks underlying epidemic processes in humans and animals are highly dynamic. The spreading of infections on such temporal networks can differ dramatically from spreading on static networks. We theoretically investigate the effects of concurrency, the number of neighbors that a node has at a given time point, on the epidemic threshold in the stochastic susceptible-infected-susceptible dynamics on temporal network models. We show that network dynamics can suppress epidemics (i.e., yield a higher epidemic threshold) when the node's concurrency is low, but can also enhance epidemics when the concurrency is high. We analytically determine different phases of this concurrency-induced transition, and confirm our results with numerical simulations.

  5. A temporal interpolation approach for dynamic reconstruction in perfusion CT

    International Nuclear Information System (INIS)

    Montes, Pau; Lauritsch, Guenter

    2007-01-01

    This article presents a dynamic CT reconstruction algorithm for objects with time dependent attenuation coefficient. Projection data acquired over several rotations are interpreted as samples of a continuous signal. Based on this idea, a temporal interpolation approach is proposed which provides the maximum temporal resolution for a given rotational speed of the CT scanner. Interpolation is performed using polynomial splines. The algorithm can be adapted to slow signals, reducing the amount of data acquired and the computational cost. A theoretical analysis of the approximations made by the algorithm is provided. In simulation studies, the temporal interpolation approach is compared with three other dynamic reconstruction algorithms based on linear regression, linear interpolation, and generalized Parker weighting. The presented algorithm exhibits the highest temporal resolution for a given sampling interval. Hence, our approach needs less input data to achieve a certain quality in the reconstruction than the other algorithms discussed or, equivalently, less x-ray exposure and computational complexity. The proposed algorithm additionally allows the possibility of using slow rotating scanners for perfusion imaging purposes

  6. Nonlinear Spatio-Temporal Dynamics and Chaos in Semiconductors

    Science.gov (United States)

    Schöll, Eckehard

    2005-08-01

    Nonlinear transport phenomena are an increasingly important aspect of modern semiconductor research. This volume deals with complex nonlinear dynamics, pattern formation, and chaotic behavior in such systems. It bridges the gap between two well-established fields: the theory of dynamic systems and nonlinear charge transport in semiconductors. This unified approach helps reveal important electronic transport instabilities. The initial chapters lay a general framework for the theoretical description of nonlinear self-organized spatio-temporal patterns, such as current filaments, field domains, fronts, and analysis of their stability. Later chapters consider important model systems in detail: impact ionization induced impurity breakdown, Hall instabilities, superlattices, and low-dimensional structures. State-of-the-art results include chaos control, spatio-temporal chaos, multistability, pattern selection, activator-inhibitor kinetics, and global coupling, linking fundamental issues to electronic device applications. This book will be of great value to semiconductor physicists and nonlinear scientists alike.

  7. Temperamental Influences on Risk-taking during Middle Childhood

    OpenAIRE

    Nyström, Beatrice

    2017-01-01

    This thesis concerns temperamental qualities and their influence on risk-taking behavior during middle childhood (7–11 years of age). Contemporary research generally agrees upon the notion that temperament constitutes two motivational systems, sensitive to punishment and reward respectively, together with a third system that is responsible for regulating the motivational systems. Risk-taking is generally regarded as the tendency to engage in potentially harmful or dangerous behaviors that at ...

  8. [Athletic performance, self-esteem and temperamental profile : Which relationship?].

    Science.gov (United States)

    Masmoudi, Jawaher; Trigui, Dorsa; Feki, Ines; Bâati, Imen; Jaoua, Abdelaziz

    2015-03-01

    Several authors emphasize the close relationship between self-esteem and athletic performance; such a relationship may raise the following question: by saying "strong" or "without any physical condition", is it a fair presentation of the individual's abilities or he reveals the most fundamental aspects of his personality, such as emotional temperament? To evaluate self-esteem, physical self and temperamental profile in a group of sportsmen, and to look for a relationship between these variables and athletic performance. We performed a cross-sectional, descriptive and analytic study in 80 young handball players of the "senior" category. We assessed self-esteem using the Rosenberg Self Esteem Scale, physical self-using the Physical Self-Inventory (PSI), and temperamental profile using the Temperament Evaluation of Memphis, Paris and San Diego Auto-questionnaire (TEMPS-A). Athletic performance was evaluated by the team coach by means of a score ranging from 1 to 10. High self-esteem was correlated to female gender (p=0.03), to an early start of physical activity (pself-esteem (pself-esteem (p=0.001). Good athletic performance was associated with hyperthymic (pself-esteem might help to achieve better athletic performance. In this intervention, the individual temperamental profile should be taken into account.

  9. Temporal dynamics of ikaite in experimental sea ice

    OpenAIRE

    S. Rysgaard; F. Wang; R. J. Galley; R. Grimm; D. Notz; M. Lemes; N.-X. Geilfus; A. Chaulk; A. A. Hare; O. Crabeck; B. G. T. Else; K. Campbell; L. L. Sørensen; J. Sievers; T. Papakyriakou

    2014-01-01

    Ikaite (CaCO3 · 6H2O) is a metastable phase of calcium carbonate that normally forms in a cold environment and/or under high pressure. Recently, ikaite crystals have been found in sea ice, and it has been suggested that their precipitation may play an important role in air–sea CO2 exchange in ice-covered seas. Little is known, however, of the spatial and temporal dynamics of ikaite in sea ice. Here we present evidence for highly dynamic ikaite precipitation and dissolution i...

  10. Estimating spatio-temporal dynamics of size-structured populations

    DEFF Research Database (Denmark)

    Kristensen, Kasper; Thygesen, Uffe Høgsbro; Andersen, Ken Haste

    2014-01-01

    with simple stock dynamics, to estimate simultaneously how size distributions and spatial distributions develop in time. We demonstrate the method for a cod population sampled by trawl surveys. Particular attention is paid to correlation between size classes within each trawl haul due to clustering...... of individuals with similar size. The model estimates growth, mortality and reproduction, after which any aspect of size-structure, spatio-temporal population dynamics, as well as the sampling process can be probed. This is illustrated by two applications: 1) tracking the spatial movements of a single cohort...

  11. Iterative analysis of cerebrovascular reactivity dynamic response by temporal decomposition.

    Science.gov (United States)

    van Niftrik, Christiaan Hendrik Bas; Piccirelli, Marco; Bozinov, Oliver; Pangalu, Athina; Fisher, Joseph A; Valavanis, Antonios; Luft, Andreas R; Weller, Michael; Regli, Luca; Fierstra, Jorn

    2017-09-01

    To improve quantitative cerebrovascular reactivity (CVR) measurements and CO 2 arrival times, we present an iterative analysis capable of decomposing different temporal components of the dynamic carbon dioxide- Blood Oxygen-Level Dependent (CO 2 -BOLD) relationship. Decomposition of the dynamic parameters included a redefinition of the voxel-wise CO 2 arrival time, and a separation from the vascular response to a stepwise increase in CO 2 (Delay to signal Plateau - DTP) and a decrease in CO 2 (Delay to signal Baseline -DTB). Twenty-five (normal) datasets, obtained from BOLD MRI combined with a standardized pseudo-square wave CO 2 change, were co-registered to generate reference atlases for the aforementioned dynamic processes to score the voxel-by-voxel deviation probability from normal range. This analysis is further illustrated in two subjects with unilateral carotid artery occlusion using these reference atlases. We have found that our redefined CO 2 arrival time resulted in the best data fit. Additionally, excluding both dynamic BOLD phases (DTP and DTB) resulted in a static CVR, that is maximal response, defined as CVR calculated only over a normocapnic and hypercapnic calibrated plateau. Decomposition and novel iterative modeling of different temporal components of the dynamic CO 2 -BOLD relationship improves quantitative CVR measurements.

  12. Ananke: temporal clustering reveals ecological dynamics of microbial communities

    Directory of Open Access Journals (Sweden)

    Michael W. Hall

    2017-09-01

    Full Text Available Taxonomic markers such as the 16S ribosomal RNA gene are widely used in microbial community analysis. A common first step in marker-gene analysis is grouping genes into clusters to reduce data sets to a more manageable size and potentially mitigate the effects of sequencing error. Instead of clustering based on sequence identity, marker-gene data sets collected over time can be clustered based on temporal correlation to reveal ecologically meaningful associations. We present Ananke, a free and open-source algorithm and software package that complements existing sequence-identity-based clustering approaches by clustering marker-gene data based on time-series profiles and provides interactive visualization of clusters, including highlighting of internal OTU inconsistencies. Ananke is able to cluster distinct temporal patterns from simulations of multiple ecological patterns, such as periodic seasonal dynamics and organism appearances/disappearances. We apply our algorithm to two longitudinal marker gene data sets: faecal communities from the human gut of an individual sampled over one year, and communities from a freshwater lake sampled over eleven years. Within the gut, the segregation of the bacterial community around a food-poisoning event was immediately clear. In the freshwater lake, we found that high sequence identity between marker genes does not guarantee similar temporal dynamics, and Ananke time-series clusters revealed patterns obscured by clustering based on sequence identity or taxonomy. Ananke is free and open-source software available at https://github.com/beiko-lab/ananke.

  13. Spatio-temporal diffusion of dynamic PET images

    International Nuclear Information System (INIS)

    Tauber, C; Chalon, S; Guilloteau, D; Stute, S; Buvat, I; Chau, M; Spiteri, P

    2011-01-01

    Positron emission tomography (PET) images are corrupted by noise. This is especially true in dynamic PET imaging where short frames are required to capture the peak of activity concentration after the radiotracer injection. High noise results in a possible bias in quantification, as the compartmental models used to estimate the kinetic parameters are sensitive to noise. This paper describes a new post-reconstruction filter to increase the signal-to-noise ratio in dynamic PET imaging. It consists in a spatio-temporal robust diffusion of the 4D image based on the time activity curve (TAC) in each voxel. It reduces the noise in homogeneous areas while preserving the distinct kinetics in regions of interest corresponding to different underlying physiological processes. Neither anatomical priors nor the kinetic model are required. We propose an automatic selection of the scale parameter involved in the diffusion process based on a robust statistical analysis of the distances between TACs. The method is evaluated using Monte Carlo simulations of brain activity distributions. We demonstrate the usefulness of the method and its superior performance over two other post-reconstruction spatial and temporal filters. Our simulations suggest that the proposed method can be used to significantly increase the signal-to-noise ratio in dynamic PET imaging.

  14. Synthesizing Dynamic Programming Algorithms from Linear Temporal Logic Formulae

    Science.gov (United States)

    Rosu, Grigore; Havelund, Klaus

    2001-01-01

    The problem of testing a linear temporal logic (LTL) formula on a finite execution trace of events, generated by an executing program, occurs naturally in runtime analysis of software. We present an algorithm which takes an LTL formula and generates an efficient dynamic programming algorithm. The generated algorithm tests whether the LTL formula is satisfied by a finite trace of events given as input. The generated algorithm runs in linear time, its constant depending on the size of the LTL formula. The memory needed is constant, also depending on the size of the formula.

  15. An investigation of temporal regularization techniques for dynamic PET reconstructions using temporal splines

    International Nuclear Information System (INIS)

    Verhaeghe, Jeroen; D'Asseler, Yves; Vandenberghe, Stefaan; Staelens, Steven; Lemahieu, Ignace

    2007-01-01

    The use of a temporal B-spline basis for the reconstruction of dynamic positron emission tomography data was investigated. Maximum likelihood (ML) reconstructions using an expectation maximization framework and maximum A-posteriori (MAP) reconstructions using the generalized expectation maximization framework were evaluated. Different parameters of the B-spline basis of such as order, number of basis functions and knot placing were investigated in a reconstruction task using simulated dynamic list-mode data. We found that a higher order basis reduced both the bias and variance. Using a higher number of basis functions in the modeling of the time activity curves (TACs) allowed the algorithm to model faster changes of the TACs, however, the TACs became noisier. We have compared ML, Gaussian postsmoothed ML and MAP reconstructions. The noise level in the ML reconstructions was controlled by varying the number of basis functions. The MAP algorithm penalized the integrated squared curvature of the reconstructed TAC. The postsmoothed ML was always outperformed in terms of bias and variance properties by the MAP and ML reconstructions. A simple adaptive knot placing strategy was also developed and evaluated. It is based on an arc length redistribution scheme during the reconstruction. The free knot reconstruction allowed a more accurate reconstruction while reducing the noise level especially for fast changing TACs such as blood input functions. Limiting the number of temporal basis functions combined with the adaptive knot placing strategy is in this case advantageous for regularization purposes when compared to the other regularization techniques

  16. Temporal dynamics of ikaite in experimental sea ice

    DEFF Research Database (Denmark)

    Rysgaard, Søren; Wang, F.; Galley, R.J.

    2014-01-01

    Ikaite (CaCO3·6H2O) is a metastable phase of calcium carbonate that normally forms in a cold environment and/or under high pressure. Recently, ikaite crystals have been found in sea ice, and it has been suggested that their precipitation may play an important role in air–sea CO2 exchange in ice......-covered seas. Little is known, however, of the spatial and temporal dynamics of ikaite in sea ice. Here we present evidence for highly dynamic ikaite precipitation and dissolution in sea ice grown at an outdoor pool of the Sea-ice Environmental Research Facility (SERF) in Manitoba, Canada. During...... the experiment, ikaite precipitated in sea ice when temperatures were below −4 C, creating three distinct zones of ikaite concentrations: (1) a millimeter-to-centimeter-thin surface layer containing frost flowers and brine skim with bulk ikaite concentrations of > 2000 μmol kg−1, (2) an internal layer...

  17. The Temporal Dynamics of Arc Expression Regulate Cognitive Flexibility.

    Science.gov (United States)

    Wall, Mark J; Collins, Dawn R; Chery, Samantha L; Allen, Zachary D; Pastuzyn, Elissa D; George, Arlene J; Nikolova, Viktoriya D; Moy, Sheryl S; Philpot, Benjamin D; Shepherd, Jason D; Müller, Jürgen; Ehlers, Michael D; Mabb, Angela M; Corrêa, Sonia A L

    2018-05-24

    Neuronal activity regulates the transcription and translation of the immediate-early gene Arc/Arg3.1, a key mediator of synaptic plasticity. Proteasome-dependent degradation of Arc tightly limits its temporal expression, yet the significance of this regulation remains unknown. We disrupted the temporal control of Arc degradation by creating an Arc knockin mouse (ArcKR) where the predominant Arc ubiquitination sites were mutated. ArcKR mice had intact spatial learning but showed specific deficits in selecting an optimal strategy during reversal learning. This cognitive inflexibility was coupled to changes in Arc mRNA and protein expression resulting in a reduced threshold to induce mGluR-LTD and enhanced mGluR-LTD amplitude. These findings show that the abnormal persistence of Arc protein limits the dynamic range of Arc signaling pathways specifically during reversal learning. Our work illuminates how the precise temporal control of activity-dependent molecules, such as Arc, regulates synaptic plasticity and is crucial for cognition. Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.

  18. Spatial and Temporal Dynamics in Air Pollution Exposure Assessment

    Science.gov (United States)

    Dias, Daniela; Tchepel, Oxana

    2018-01-01

    Analyzing individual exposure in urban areas offers several challenges where both the individual’s activities and air pollution levels demonstrate a large degree of spatial and temporal dynamics. This review article discusses the concepts, key elements, current developments in assessing personal exposure to urban air pollution (seventy-two studies reviewed) and respective advantages and disadvantages. A new conceptual structure to organize personal exposure assessment methods is proposed according to two classification criteria: (i) spatial-temporal variations of individuals’ activities (point-fixed or trajectory based) and (ii) characterization of air quality (variable or uniform). This review suggests that the spatial and temporal variability of urban air pollution levels in combination with indoor exposures and individual’s time-activity patterns are key elements of personal exposure assessment. In the literature review, the majority of revised studies (44 studies) indicate that the trajectory based with variable air quality approach provides a promising framework for tackling the important question of inter- and intra-variability of individual exposure. However, future quantitative comparison between the different approaches should be performed, and the selection of the most appropriate approach for exposure quantification should take into account the purpose of the health study. This review provides a structured basis for the intercomparing of different methodologies and to make their advantages and limitations more transparent in addressing specific research objectives. PMID:29558426

  19. Lateralization for dynamic facial expressions in human superior temporal sulcus.

    Science.gov (United States)

    De Winter, François-Laurent; Zhu, Qi; Van den Stock, Jan; Nelissen, Koen; Peeters, Ronald; de Gelder, Beatrice; Vanduffel, Wim; Vandenbulcke, Mathieu

    2015-02-01

    Most face processing studies in humans show stronger activation in the right compared to the left hemisphere. Evidence is largely based on studies with static stimuli focusing on the fusiform face area (FFA). Hence, the pattern of lateralization for dynamic faces is less clear. Furthermore, it is unclear whether this property is common to human and non-human primates due to predisposing processing strategies in the right hemisphere or that alternatively left sided specialization for language in humans could be the driving force behind this phenomenon. We aimed to address both issues by studying lateralization for dynamic facial expressions in monkeys and humans. Therefore, we conducted an event-related fMRI experiment in three macaques and twenty right handed humans. We presented human and monkey dynamic facial expressions (chewing and fear) as well as scrambled versions to both species. We studied lateralization in independently defined face-responsive and face-selective regions by calculating a weighted lateralization index (LIwm) using a bootstrapping method. In order to examine if lateralization in humans is related to language, we performed a separate fMRI experiment in ten human volunteers including a 'speech' expression (one syllable non-word) and its scrambled version. Both within face-responsive and selective regions, we found consistent lateralization for dynamic faces (chewing and fear) versus scrambled versions in the right human posterior superior temporal sulcus (pSTS), but not in FFA nor in ventral temporal cortex. Conversely, in monkeys no consistent pattern of lateralization for dynamic facial expressions was observed. Finally, LIwms based on the contrast between different types of dynamic facial expressions (relative to scrambled versions) revealed left-sided lateralization in human pSTS for speech-related expressions compared to chewing and emotional expressions. To conclude, we found consistent laterality effects in human posterior STS but not

  20. The relationship between temperamental traits and the level of performance of an eye-hand co-ordination task in jet pilots.

    Science.gov (United States)

    Biernacki, Marcin; Tarnowski, Adam

    2008-01-01

    When assessing the psychological suitability for the profession of a pilot, it is important to consider personality traits and psychomotor abilities. Our study aimed at estimating the role of temperamental traits as components of pilots' personality in eye-hand co-ordination. The assumption was that differences in the escalation of the level of temperamental traits, as measured with the Formal Characteristic of Behaviour-Temperament Inventory (FCB-TI), will significantly influence eye-hand co-ordination. At the level of general scores, enhanced briskness proved to be the most important trait for eye-hand co-ordination. An analysis of partial scores additionally underlined the importance of sensory sensitivity, endurance and activity. The application of eye-hand co-ordination tasks, which involve energetic and temporal dimensions of performance, helped to disclose the role of biologically-based personality traits in psychomotor performance. The implication of these findings for selecting pilots is discussed.

  1. Spatio-temporal dynamics of the tropical rain forest

    Energy Technology Data Exchange (ETDEWEB)

    Chave, J. [CEN Saclay, Gif-sur-Yvette (France). Service de Physique de l' Etat Condense

    2000-07-01

    Mechanisms which drive the dynamics of forest ecosystems are complex, from seedling establishment to pollination, and seed dispersal by animals, running water or wind. These processes are more complex when the ecosystem shelters a large number of species and of vegetative forms, as it is the case in the tropical rainforest. To take them into account, we must develop and use models. I present a review of the fundamental mechanisms for the of a natural forest dynamics - photosynthesis, tree growth, recruitment and mortality - as well as a description of the past and of the present of tropical rainforests. This information is used to develop a spatially-explicit and individual-based forest model. Simplified models are deduced from it, and they serve to address more specific issues, such as the resilience of the forest to climate disturbances, or savanna-forest dynamics. The last topic is related to the spatio-temporal description of tropical plant biodiversity. A detailed introduction to the problem is provided, and models accounting for the maintenance of diversity are compared. These models include non spatial as well a spatial approaches (branching anihilating random walks and voter model with mutation). (orig.)

  2. Temporal dynamics of glyoxalase 1 in secondary neuronal injury.

    Directory of Open Access Journals (Sweden)

    Philipp Pieroh

    Full Text Available BACKGROUND: Enhanced glycolysis leads to elevated levels of the toxic metabolite methylglyoxal which contributes to loss of protein-function, metabolic imbalance and cell death. Neurons were shown being highly susceptible to methylglyoxal toxicity. Glyoxalase 1 as an ubiquitous enzyme reflects the main detoxifying enzyme of methylglyoxal and underlies changes during aging and neurodegeneration. However, little is known about dynamics of Glyoxalase 1 following neuronal lesions so far. METHODS: To determine a possible involvement of Glyoxalase 1 in acute brain injury, we analysed the temporal dynamics of Glyoxalase 1 distribution and expression by immunohistochemistry and Western Blot analysis. Organotypic hippocampal slice cultures were excitotoxically (N-methyl-D-aspartate, 50 µM for 4 hours lesioned in vitro (5 minutes to 72 hours. Additionally, permanent middle cerebral artery occlusion was performed (75 minutes to 60 days. RESULTS: We found (i a predominant localisation of Glyoxalase 1 in endothelial cells in non-lesioned brains (ii a time-dependent up-regulation and re-distribution of Glyoxalase 1 in neurons and astrocytes and (iii a strong increase in Glyoxalase 1 dimers after neuronal injury (24 hours to 72 hours when compared to monomers of the protein. CONCLUSIONS: The high dynamics of Glyoxalase 1 expression and distribution following neuronal injury may indicate a novel role of Glyoxalase 1.

  3. Temporal languages for simulation and analysis of the dynamics within an organisation.

    NARCIS (Netherlands)

    Jonker, C.M.; Treur, J.; Wijngaards, W.C.A.

    2002-01-01

    In this paper a modelling approach to the dynamics within a multi- agent organisation is presented. A declarative, executable temporal modelling language for organisation dynamics is proposed as a basis for simulation. Moreover, to be able to specify and analyse dynamic properties, another temporal

  4. Temporal dynamics of biogeochemical processes at the Norman Landfill site

    Science.gov (United States)

    Arora, Bhavna; Mohanty, Binayak P.; McGuire, Jennifer T.; Cozzarelli, Isabelle M.

    2013-01-01

    The temporal variability observed in redox sensitive species in groundwater can be attributed to coupled hydrological, geochemical, and microbial processes. These controlling processes are typically nonstationary, and distributed across various time scales. Therefore, the purpose of this study is to investigate biogeochemical data sets from a municipal landfill site to identify the dominant modes of variation and determine the physical controls that become significant at different time scales. Data on hydraulic head, specific conductance, δ2H, chloride, sulfate, nitrate, and nonvolatile dissolved organic carbon were collected between 1998 and 2000 at three wells at the Norman Landfill site in Norman, OK. Wavelet analysis on this geochemical data set indicates that variations in concentrations of reactive and conservative solutes are strongly coupled to hydrologic variability (water table elevation and precipitation) at 8 month scales, and to individual eco-hydrogeologic framework (such as seasonality of vegetation, surface-groundwater dynamics) at 16 month scales. Apart from hydrologic variations, temporal variability in sulfate concentrations can be associated with different sources (FeS cycling, recharge events) and sinks (uptake by vegetation) depending on the well location and proximity to the leachate plume. Results suggest that nitrate concentrations show multiscale behavior across temporal scales for different well locations, and dominant variability in dissolved organic carbon for a closed municipal landfill can be larger than 2 years due to its decomposition and changing content. A conceptual framework that explains the variability in chemical concentrations at different time scales as a function of hydrologic processes, site-specific interactions, and/or coupled biogeochemical effects is also presented.

  5. Noise-induced temporal dynamics in Turing systems

    KAUST Repository

    Schumacher, Linus J.

    2013-04-25

    We examine the ability of intrinsic noise to produce complex temporal dynamics in Turing pattern formation systems, with particular emphasis on the Schnakenberg kinetics. Using power spectral methods, we characterize the behavior of the system using stochastic simulations at a wide range of points in parameter space and compare with analytical approximations. Specifically, we investigate whether polarity switching of stochastic patterns occurs at a defined frequency. We find that it can do so in individual realizations of a stochastic simulation, but that the frequency is not defined consistently across realizations in our samples of parameter space. Further, we examine the effect of noise on deterministically predicted traveling waves and find them increased in amplitude and decreased in speed. © 2013 American Physical Society.

  6. Dynamic Raman imaging system with high spatial and temporal resolution

    Science.gov (United States)

    Wang, Lei; Dai, Yinzhen; He, Hao; Lv, Ruiqi; Zong, Cheng; Ren, Bin

    2017-09-01

    There is an increasing need to study dynamic changing systems with significantly high spatial and temporal resolutions. In this work, we integrated point-scanning, line-scanning, and wide-field Raman imaging techniques into a single system. By using an Electron Multiplying CCD (EMCCD) with a high gain and high frame rate, we significantly reduced the time required for wide-field imaging, making it possible to monitor the electrochemical reactions in situ. The highest frame rate of EMCDD was ˜50 fps, and the Raman images for a specific Raman peak can be obtained by passing the signal from the sample through the Liquid Crystal Tunable Filter. The spatial resolutions of scanning imaging and wide-field imaging with a 100× objective (NA = 0.9) are 0.5 × 0.5 μm2 and 0.36 × 0.36 μm2, respectively. The system was used to study the surface plasmon resonance of Au nanorods, the surface-enhanced Raman scattering signal distribution for Au Nanoparticle aggregates, and dynamic Raman imaging of an electrochemical reacting system.

  7. Learning predictive statistics from temporal sequences: Dynamics and strategies.

    Science.gov (United States)

    Wang, Rui; Shen, Yuan; Tino, Peter; Welchman, Andrew E; Kourtzi, Zoe

    2017-10-01

    Human behavior is guided by our expectations about the future. Often, we make predictions by monitoring how event sequences unfold, even though such sequences may appear incomprehensible. Event structures in the natural environment typically vary in complexity, from simple repetition to complex probabilistic combinations. How do we learn these structures? Here we investigate the dynamics of structure learning by tracking human responses to temporal sequences that change in structure unbeknownst to the participants. Participants were asked to predict the upcoming item following a probabilistic sequence of symbols. Using a Markov process, we created a family of sequences, from simple frequency statistics (e.g., some symbols are more probable than others) to context-based statistics (e.g., symbol probability is contingent on preceding symbols). We demonstrate the dynamics with which individuals adapt to changes in the environment's statistics-that is, they extract the behaviorally relevant structures to make predictions about upcoming events. Further, we show that this structure learning relates to individual decision strategy; faster learning of complex structures relates to selection of the most probable outcome in a given context (maximizing) rather than matching of the exact sequence statistics. Our findings provide evidence for alternate routes to learning of behaviorally relevant statistics that facilitate our ability to predict future events in variable environments.

  8. A full time-domain approach to spatio-temporal dynamics of semiconductor lasers. II. Spatio-temporal dynamics

    Science.gov (United States)

    Böhringer, Klaus; Hess, Ortwin

    The spatio-temporal dynamics of novel semiconductor lasers is discussed on the basis of a space- and momentum-dependent full time-domain approach. To this means the space-, time-, and momentum-dependent Full-Time Domain Maxwell Semiconductor Bloch equations, derived and discussed in our preceding paper I [K. Böhringer, O. Hess, A full time-domain approach to spatio-temporal dynamics of semiconductor lasers. I. Theoretical formulation], are solved by direct numerical integration. Focussing on the device physics of novel semiconductor lasers that profit, in particular, from recent advances in nanoscience and nanotechnology, we discuss the examples of photonic band edge surface emitting lasers (PBE-SEL) and semiconductor disc lasers (SDLs). It is demonstrated that photonic crystal effects can be obtained for finite crystal structures, and leading to a significant improvement in laser performance such as reduced lasing thresholds. In SDLs, a modern device concept designed to increase the power output of surface-emitters in combination with near-diffraction-limited beam quality, we explore the complex interplay between the intracavity optical fields and the quantum well gain material in SDL structures. Our simulations reveal the dynamical balance between carrier generation due to pumping into high energy states, momentum relaxation of carriers, and stimulated recombination from states near the band edge. Our full time-domain approach is shown to also be an excellent framework for the modelling of the interaction of high-intensity femtosecond and picosecond pulses with semiconductor nanostructures. It is demonstrated that group velocity dispersion, dynamical gain saturation and fast self-phase modulation (SPM) are the main causes for the induced changes and asymmetries in the amplified pulse shape and spectrum of an ultrashort high-intensity pulse. We attest that the time constants of the intraband scattering processes are critical to gain recovery. Moreover, we present

  9. Original article Temperamental variation in learned irrelevance in humans

    Directory of Open Access Journals (Sweden)

    Aleksandra Gruszka

    2015-07-01

    Full Text Available Background Learned irrelevance (LIRR represents one of the mechanisms of attentional set-shifting and refers to the inability to attend to, or to learn about, any aspect of a stimulus previously experienced as irrelevant. Although it has been extensively studied in the context of clinical populations, not much is known about LIRR effects in relation to normal variation in individual differences. The present study was designed to assess how temperamental factors may modulate LIRR. Participants and procedures Sixty-eight healthy volunteers performed a visual discrimination learning task modelled after Wisconsin Card Sorting Test. To test the susceptibility to learned irrelevance, participants were expected to shift their attention either to a dimension that prior to the extra-dimensional shift was completely irrelevant, or to a dimension that was previously partly correlated with reinforcement. Temperamental traits were assessed using the Formal Characteristics of Behaviour-Temperament Inventory (Zawadzki & Strelau, 1997. Intelligence level was stratified according to Raven’s Advanced Progressive Matrices (Raven, Raven, & Court, 2003. Results Low level of Briskness and high level of Perseverance were related to enhanced susceptibility to LIRR. High levels of Activity and Emotional Reactivity were related to the poorer performance on the extra-dimensional set-shifting. No effects of other temperament characteristics or intelligence on LIRR were observed. Conclusions The results confirm a strong variation in LIRR related to individual differences in temperament, which appears to be unrelated to DA function. Our results highlight the importance of considering individual differences in studies on cognitive control.

  10. Quality of a fished resource: Assessing spatial and temporal dynamics.

    Directory of Open Access Journals (Sweden)

    Sarah J Teck

    Full Text Available Understanding spatio-temporal variability in the demography of harvested species is essential to improve sustainability, especially if there is large geographic variation in demography. Reproductive patterns commonly vary spatially, which is particularly important for management of "roe"-based fisheries, since profits depend on both the number and reproductive condition of individuals. The red sea urchin, Mesocentrotus franciscanus, is harvested in California for its roe (gonad, which is sold to domestic and international sushi markets. The primary driver of price within this multi-million-dollar industry is gonad quality. A relatively simple measure of the fraction of the body mass that is gonad, the gonadosomatic index (GSI, provides important insight into the ecological and environmental factors associated with variability in reproductive quality, and hence value within the industry. We identified the seasonality of the reproductive cycle and determined whether it varied within a heavily fished region. We found that fishermen were predictable both temporally and spatially in collecting urchins according to the reproductive dynamics of urchins. We demonstrated the use of red sea urchin GSI as a simple, quantitative tool to predict quality, effort, landings, price, and value of the fishery. We found that current management is not effectively realizing some objectives for the southern California fishery, since the reproductive cycle does not match the cycle in northern California, where these management guidelines were originally shaped. Although regulations may not be meeting initial management goals, the scheme may in fact provide conservation benefits by curtailing effort during part of the high-quality fishing season right before spawning.

  11. Temporal dynamics of ikaite in experimental sea ice

    Science.gov (United States)

    Rysgaard, S.; Wang, F.; Galley, R. J.; Grimm, R.; Notz, D.; Lemes, M.; Geilfus, N.-X.; Chaulk, A.; Hare, A. A.; Crabeck, O.; Else, B. G. T.; Campbell, K.; Sørensen, L. L.; Sievers, J.; Papakyriakou, T.

    2014-08-01

    Ikaite (CaCO3 · 6H2O) is a metastable phase of calcium carbonate that normally forms in a cold environment and/or under high pressure. Recently, ikaite crystals have been found in sea ice, and it has been suggested that their precipitation may play an important role in air-sea CO2 exchange in ice-covered seas. Little is known, however, of the spatial and temporal dynamics of ikaite in sea ice. Here we present evidence for highly dynamic ikaite precipitation and dissolution in sea ice grown at an outdoor pool of the Sea-ice Environmental Research Facility (SERF) in Manitoba, Canada. During the experiment, ikaite precipitated in sea ice when temperatures were below -4 °C, creating three distinct zones of ikaite concentrations: (1) a millimeter-to-centimeter-thin surface layer containing frost flowers and brine skim with bulk ikaite concentrations of >2000 μmol kg-1, (2) an internal layer with ikaite concentrations of 200-400 μmol kg-1, and (3) a bottom layer with ikaite concentrations of ikaite crystals to dissolve. Manual removal of the snow cover allowed the sea ice to cool and brine salinities to increase, resulting in rapid ikaite precipitation. The observed ikaite concentrations were on the same order of magnitude as modeled by FREZCHEM, which further supports the notion that ikaite concentration in sea ice increases with decreasing temperature. Thus, varying snow conditions may play a key role in ikaite precipitation and dissolution in sea ice. This could have a major implication for CO2 exchange with the atmosphere and ocean that has not been accounted for previously.

  12. Forecasting Temporal Dynamics of Cutaneous Leishmaniasis in Northeast Brazil

    Science.gov (United States)

    Lewnard, Joseph A.; Jirmanus, Lara; Júnior, Nivison Nery; Machado, Paulo R.; Glesby, Marshall J.; Ko, Albert I.; Carvalho, Edgar M.; Schriefer, Albert; Weinberger, Daniel M.

    2014-01-01

    Introduction Cutaneous leishmaniasis (CL) is a vector-borne disease of increasing importance in northeastern Brazil. It is known that sandflies, which spread the causative parasites, have weather-dependent population dynamics. Routinely-gathered weather data may be useful for anticipating disease risk and planning interventions. Methodology/Principal Findings We fit time series models using meteorological covariates to predict CL cases in a rural region of Bahía, Brazil from 1994 to 2004. We used the models to forecast CL cases for the period 2005 to 2008. Models accounting for meteorological predictors reduced mean squared error in one, two, and three month-ahead forecasts by up to 16% relative to forecasts from a null model accounting only for temporal autocorrelation. Significance These outcomes suggest CL risk in northeastern Brazil might be partially dependent on weather. Responses to forecasted CL epidemics may include bolstering clinical capacity and disease surveillance in at-risk areas. Ecological mechanisms by which weather influences CL risk merit future research attention as public health intervention targets. PMID:25356734

  13. Temporal dynamics of top predators interactions in the Barents Sea.

    Science.gov (United States)

    Durant, Joël M; Skern-Mauritzen, Mette; Krasnov, Yuri V; Nikolaeva, Natalia G; Lindstrøm, Ulf; Dolgov, Andrey

    2014-01-01

    The Barents Sea system is often depicted as a simple food web in terms of number of dominant feeding links. The most conspicuous feeding link is between the Northeast Arctic cod Gadus morhua, the world's largest cod stock which is presently at a historical high level, and capelin Mallotus villosus. The system also holds diverse seabird and marine mammal communities. Previous diet studies may suggest that these top predators (cod, bird and sea mammals) compete for food particularly with respect to pelagic fish such as capelin and juvenile herring (Clupea harengus), and krill. In this paper we explored the diet of some Barents Sea top predators (cod, Black-legged kittiwake Rissa tridactyla, Common guillemot Uria aalge, and Minke whale Balaenoptera acutorostrata). We developed a GAM modelling approach to analyse the temporal variation diet composition within and between predators, to explore intra- and inter-specific interactions. The GAM models demonstrated that the seabird diet is temperature dependent while the diet of Minke whale and cod is prey dependent; Minke whale and cod diets depend on the abundance of herring and capelin, respectively. There was significant diet overlap between cod and Minke whale, and between kittiwake and guillemot. In general, the diet overlap between predators increased with changes in herring and krill abundances. The diet overlap models developed in this study may help to identify inter-specific interactions and their dynamics that potentially affect the stocks targeted by fisheries.

  14. Spatial-temporal dynamics of broadband terahertz Bessel beam propagation

    International Nuclear Information System (INIS)

    Semenova, V A; Kulya, M S; Bespalov, V G

    2016-01-01

    The unique properties of narrowband and broadband terahertz Bessel beams have led to a number of their applications in different fields, for example, for the depth of focusing and resolution enhancement in terahertz imaging. However, broadband terahertz Bessel beams can probably be also used for the diffraction minimization in the short-range broadband terahertz communications. For this purpose, the study of spatial-temporal dynamics of the broadband terahertz Bessel beams is needed. Here we present a simulation-based study of the propagating in non-dispersive medium broadband Bessel beams generated by a conical axicon lens. The algorithm based on scalar diffraction theory was used to obtain the spatial amplitude and phase distributions of the Bessel beam in the frequency range from 0.1 to 3 THz at the distances 10-200 mm from the axicon. Bessel beam field is studied for the different spectral components of the initial pulse. The simulation results show that for the given parameters of the axicon lens one can obtain the Gauss-Bessel beam generation in the spectral range from 0.1 to 3 THz. The length of non-diffraction propagation for a different spectral components was measured, and it was shown that for all spectral components of the initial pulse this length is about 130 mm. (paper)

  15. Temporal dynamics of access to consciousness in the attentional blink.

    Science.gov (United States)

    Kranczioch, Cornelia; Debener, Stefan; Maye, Alexander; Engel, Andreas K

    2007-09-01

    Presentation of two targets in close temporal succession often results in an impairment of conscious perception for the second stimulus. Previous studies have identified several electrophysiological correlates for this so-called 'attentional blink'. Components of the event-related potential (ERP) such as the N2 and the P3, but also oscillatory brain signals have been shown to distinguish between detected and missed stimuli, and thus, conscious perception. Here we investigate oscillatory responses that specifically relate to conscious stimulus processing together with potential ERP predictors. Our results show that successful target detection is associated with enhanced coherence in the low beta frequency range, but a decrease in alpha coherence before and during target presentation. In addition, we find an inverse relation between the P3 amplitudes associated with the first and second target. We conclude that the resources allocated to first and second target processing are directly mirrored by the P3 component and, moreover, that brain states before and during stimulus presentation, as reflected by oscillatory brain activity, strongly determine the access to consciousness. Thus, becoming aware of a stimulus seems to depend on the dynamic interaction between a number of widely distributed neural processes, rather than on the modulation of one single process or component.

  16. A dynamic neural field model of temporal order judgments.

    Science.gov (United States)

    Hecht, Lauren N; Spencer, John P; Vecera, Shaun P

    2015-12-01

    Temporal ordering of events is biased, or influenced, by perceptual organization-figure-ground organization-and by spatial attention. For example, within a region assigned figural status or at an attended location, onset events are processed earlier (Lester, Hecht, & Vecera, 2009; Shore, Spence, & Klein, 2001), and offset events are processed for longer durations (Hecht & Vecera, 2011; Rolke, Ulrich, & Bausenhart, 2006). Here, we present an extension of a dynamic field model of change detection (Johnson, Spencer, Luck, & Schöner, 2009; Johnson, Spencer, & Schöner, 2009) that accounts for both the onset and offset performance for figural and attended regions. The model posits that neural populations processing the figure are more active, resulting in a peak of activation that quickly builds toward a detection threshold when the onset of a target is presented. This same enhanced activation for some neural populations is maintained when a present target is removed, creating delays in the perception of the target's offset. We discuss the broader implications of this model, including insights regarding how neural activation can be generated in response to the disappearance of information. (c) 2015 APA, all rights reserved).

  17. Temporal dynamics of hippocampal neurogenesis in chronic neurodegeneration

    Science.gov (United States)

    Suzzi, Stefano; Vargas-Caballero, Mariana; Fransen, Nina L.; Al-Malki, Hussain; Cebrian-Silla, Arantxa; Garcia-Verdugo, Jose Manuel; Riecken, Kristoffer; Fehse, Boris; Perry, V. Hugh

    2014-01-01

    The study of neurogenesis during chronic neurodegeneration is crucial in order to understand the intrinsic repair mechanisms of the brain, and key to designing therapeutic strategies. In this study, using an experimental model of progressive chronic neurodegeneration, murine prion disease, we define the temporal dynamics of the generation, maturation and integration of new neurons in the hippocampal dentate gyrus, using dual pulse-chase, multicolour γ-retroviral tracing, transmission electron microscopy and patch-clamp. We found increased neurogenesis during the progression of prion disease, which partially counteracts the effects of chronic neurodegeneration, as evidenced by blocking neurogenesis with cytosine arabinoside, and helps to preserve the hippocampal function. Evidence obtained from human post-mortem samples, of both variant Creutzfeldt-Jakob disease and Alzheimer’s disease patients, also suggests increased neurogenic activity. These results open a new avenue into the exploration of the effects and regulation of neurogenesis during chronic neurodegeneration, and offer a new model to reproduce the changes observed in human neurodegenerative diseases. PMID:24941947

  18. Temporal dynamics in microbial soil communities at anthrax carcass sites.

    Science.gov (United States)

    Valseth, Karoline; Nesbø, Camilla L; Easterday, W Ryan; Turner, Wendy C; Olsen, Jaran S; Stenseth, Nils Chr; Haverkamp, Thomas H A

    2017-09-26

    Anthrax is a globally distributed disease affecting primarily herbivorous mammals. It is caused by the soil-dwelling and spore-forming bacterium Bacillus anthracis. The dormant B. anthracis spores become vegetative after ingestion by grazing mammals. After killing the host, B. anthracis cells return to the soil where they sporulate, completing the lifecycle of the bacterium. Here we present the first study describing temporal microbial soil community changes in Etosha National Park, Namibia, after decomposition of two plains zebra (Equus quagga) anthrax carcasses. To circumvent state-associated-challenges (i.e. vegetative cells/spores) we monitored B. anthracis throughout the period using cultivation, qPCR and shotgun metagenomic sequencing. The combined results suggest that abundance estimation of spore-forming bacteria in their natural habitat by DNA-based approaches alone is insufficient due to poor recovery of DNA from spores. However, our combined approached allowed us to follow B. anthracis population dynamics (vegetative cells and spores) in the soil, along with closely related organisms from the B. cereus group, despite their high sequence similarity. Vegetative B. anthracis abundance peaked early in the time-series and then dropped when cells either sporulated or died. The time-series revealed that after carcass deposition, the typical semi-arid soil community (e.g. Frankiales and Rhizobiales species) becomes temporarily dominated by the orders Bacillales and Pseudomonadales, known to contain plant growth-promoting species. Our work indicates that complementing DNA based approaches with cultivation may give a more complete picture of the ecology of spore forming pathogens. Furthermore, the results suggests that the increased vegetation biomass production found at carcass sites is due to both added nutrients and the proliferation of microbial taxa that can be beneficial for plant growth. Thus, future B. anthracis transmission events at carcass sites may be

  19. Dynamic encoding of speech sequence probability in human temporal cortex.

    Science.gov (United States)

    Leonard, Matthew K; Bouchard, Kristofer E; Tang, Claire; Chang, Edward F

    2015-05-06

    Sensory processing involves identification of stimulus features, but also integration with the surrounding sensory and cognitive context. Previous work in animals and humans has shown fine-scale sensitivity to context in the form of learned knowledge about the statistics of the sensory environment, including relative probabilities of discrete units in a stream of sequential auditory input. These statistics are a defining characteristic of one of the most important sequential signals humans encounter: speech. For speech, extensive exposure to a language tunes listeners to the statistics of sound sequences. To address how speech sequence statistics are neurally encoded, we used high-resolution direct cortical recordings from human lateral superior temporal cortex as subjects listened to words and nonwords with varying transition probabilities between sound segments. In addition to their sensitivity to acoustic features (including contextual features, such as coarticulation), we found that neural responses dynamically encoded the language-level probability of both preceding and upcoming speech sounds. Transition probability first negatively modulated neural responses, followed by positive modulation of neural responses, consistent with coordinated predictive and retrospective recognition processes, respectively. Furthermore, transition probability encoding was different for real English words compared with nonwords, providing evidence for online interactions with high-order linguistic knowledge. These results demonstrate that sensory processing of deeply learned stimuli involves integrating physical stimulus features with their contextual sequential structure. Despite not being consciously aware of phoneme sequence statistics, listeners use this information to process spoken input and to link low-level acoustic representations with linguistic information about word identity and meaning. Copyright © 2015 the authors 0270-6474/15/357203-12$15.00/0.

  20. Temporal dynamics of blue and green virtual water trade networks

    Science.gov (United States)

    Konar, M.; Dalin, C.; Hanasaki, N.; Rinaldo, A.; Rodriguez-Iturbe, I.

    2012-12-01

    Global food security increasingly relies on the trade of food commodities. Freshwater resources are essential to agricultural production and are thus embodied in the trade of food commodities, referred to as "virtual water trade." Agricultural production predominantly relies on rainwater (i.e., "green water"), though irrigation (i.e., "blue water") does play an important role. These different sources of water have distinctly different opportunity costs, which may be reflected in the way these resources are traded. Thus, the temporal dynamics of the virtual water trade networks from these distinct water sources require characterization. We find that 42 × 109 m3 blue and 310 × 109 m3 green water was traded in 1986, growing to 78 × 109 m3 blue and 594 × 109 m3 green water traded in 2008. Three nations dominate the export of green water resources: the USA, Argentina, and Brazil. As a country increases its export trade partners it tends to export relatively more blue water. However, as a country increases its import trade partners it does not preferentially import water from a specific source. The amount of virtual water that a country imports by increasing its import trade partners has been decreasing over time, with the exception of the soy trade. Both blue and green virtual water networks are efficient: 119 × 109 m3 blue and 105 × 109 m3 green water were saved in 2008. Importantly, trade has been increasingly saving water over time, due to the intensification of crop trade on more water-efficient links.

  1. How Well Do Students in Secondary School Understand Temporal Development of Dynamical Systems?

    Science.gov (United States)

    Forjan, Matej; Grubelnik, Vladimir

    2015-01-01

    Despite difficulties understanding the dynamics of complex systems only simple dynamical systems without feedback connections have been taught in secondary school physics. Consequently, students do not have opportunities to develop intuition of temporal development of systems, whose dynamics are conditioned by the influence of feedback processes.…

  2. Temporally Dynamic, Spatially Static, Cobble Bedforms In Reversing Subtidal Currents

    Science.gov (United States)

    Abdulkade, Akirat; Carling, Paul; Zong, Quanli; Leyland, Julian; Thompson, Charlie

    2016-04-01

    Cobble bedforms, transverse to the reversing tidal currents, are exposed at extreme low-water Spring tides on an inter-tidal bedrock shelf in the macro-tidal Severn Estuary, UK. Near-bed flow velocities during Spring tides can exceed 1.5m/s, with water depths varying from zero to in excess of 10m. During neap tides the bedforms are not exposed, and sediment is expected to be of limited mobility. When exposed, the bedform geometry tends to be asymmetric; orientated down estuary with the ebb current. During Spring tides, vigorous bedload transport of gravel (including large cobbles) occurs during both flood and ebb over the crests and yet, despite this temporal dynamism, the bedforms remain spatially static over long time periods or show weak down-estuary migration. Stasis implies that the tidal bedload transport vectors are essentially in balance. Near-bed shear stress and bed roughness values vary systematically with the Spring-tide current speeds and the predicted grain-size of the bed load using the Shields criterion is in accord with observed coarser grain-sizes in transport. These hydrodynamic data, delimited by estimates of the threshold of motion, and integrated over either flood or ebb tides are being used to explain the apparent stability of the bedforms. The bulk hydraulic data are supplemented by particle tracer studies and laser-scanning of bed configurations between tides. The high-energy environment results in two forms of armouring. Pronounced steep imbrication of platy-cobbles visible on the exposed up-estuary side of dunes is probably disrupted during flood tides leading to rapid reworking of the toe deposits facing up-estuary. In contrast, some crest and leeside locations have been stable for prolonged periods such that closely-fitted fabrics result; these portions of the bedforms are static and effectively are 'armour-plated'. Ebb-tide deposits of finer, ephemeral sandy-units occur on the down estuary side of the bedforms. Sandy-units (although

  3. A dynamic texture based approach to recognition of facial actions and their temporal models

    NARCIS (Netherlands)

    Koelstra, Sander; Pantic, Maja; Patras, Ioannis (Yannis)

    2010-01-01

    In this work, we propose a dynamic texture-based approach to the recognition of facial Action Units (AUs, atomic facial gestures) and their temporal models (i.e., sequences of temporal segments: neutral, onset, apex, and offset) in near-frontal-view face videos. Two approaches to modeling the

  4. Temporal and spatial dynamics of mineral levels of forage, soil and ...

    African Journals Online (AJOL)

    Temporal and spatial dynamics of mineral levels of forage, soil and cattle blood ... In the plain lands, local variations occurred for soil phosphorus and magnesium. ... Rangeland improvement and supplementation strategies are suggested to ...

  5. Community ecology in 3D: Tensor decomposition reveals spatio-temporal dynamics of large ecological communities

    DEFF Research Database (Denmark)

    Frelat, Romain; Lindegren, Martin; Dencker, Tim Spaanheden

    2017-01-01

    it to multiple dimensions. This extension allows for the synchronized study of multiple ecological variables measured repeatedly in time and space. We applied this comprehensive approach to explore the spatio-temporal dynamics of 65 demersal fish species in the North Sea, a marine ecosystem strongly altered...... by human activities and climate change. Our case study demonstrates how tensor decomposition can successfully (i) characterize the main spatio-temporal patterns and trends in species abundances, (ii) identify sub-communities of species that share similar spatial distribution and temporal dynamics, and (iii...

  6. Graph regularized nonnegative matrix factorization for temporal link prediction in dynamic networks

    Science.gov (United States)

    Ma, Xiaoke; Sun, Penggang; Wang, Yu

    2018-04-01

    Many networks derived from society and nature are temporal and incomplete. The temporal link prediction problem in networks is to predict links at time T + 1 based on a given temporal network from time 1 to T, which is essential to important applications. The current algorithms either predict the temporal links by collapsing the dynamic networks or collapsing features derived from each network, which are criticized for ignoring the connection among slices. to overcome the issue, we propose a novel graph regularized nonnegative matrix factorization algorithm (GrNMF) for the temporal link prediction problem without collapsing the dynamic networks. To obtain the feature for each network from 1 to t, GrNMF factorizes the matrix associated with networks by setting the rest networks as regularization, which provides a better way to characterize the topological information of temporal links. Then, the GrNMF algorithm collapses the feature matrices to predict temporal links. Compared with state-of-the-art methods, the proposed algorithm exhibits significantly improved accuracy by avoiding the collapse of temporal networks. Experimental results of a number of artificial and real temporal networks illustrate that the proposed method is not only more accurate but also more robust than state-of-the-art approaches.

  7. Dynamic interactions between hydrogeological and exposure parameters in daily dose prediction under uncertainty and temporal variability

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Vikas, E-mail: vikas.kumar@urv.cat [Department of Chemical Engineering, Rovira i Virgili University, Tarragona 43007 (Spain); Barros, Felipe P.J. de [Sonny Astani Department of Civil and Environmental Engineering, University of Southern California, Los Angeles 90089, CA (United States); Schuhmacher, Marta [Department of Chemical Engineering, Rovira i Virgili University, Tarragona 43007 (Spain); Fernàndez-Garcia, Daniel; Sanchez-Vila, Xavier [Hydrogeology Group, Department of Geotechnical Engineering and Geosciences, University Politècnica de Catalunya-BarcelonaTech, Barcelona 08034 (Spain)

    2013-12-15

    Highlights: • Dynamic parametric interaction in daily dose prediction under uncertainty. • Importance of temporal dynamics associated with the dose. • Different dose experienced by different population cohorts as a function of time. • Relevance of uncertainty reduction in the input parameters shows temporal dynamism. -- Abstract: We study the time dependent interaction between hydrogeological and exposure parameters in daily dose predictions due to exposure of humans to groundwater contamination. Dose predictions are treated stochastically to account for an incomplete hydrogeological and geochemical field characterization, and an incomplete knowledge of the physiological response. We used a nested Monte Carlo framework to account for uncertainty and variability arising from both hydrogeological and exposure variables. Our interest is in the temporal dynamics of the total dose and their effects on parametric uncertainty reduction. We illustrate the approach to a HCH (lindane) pollution problem at the Ebro River, Spain. The temporal distribution of lindane in the river water can have a strong impact in the evaluation of risk. The total dose displays a non-linear effect on different population cohorts, indicating the need to account for population variability. We then expand the concept of Comparative Information Yield Curves developed earlier (see de Barros et al. [29]) to evaluate parametric uncertainty reduction under temporally variable exposure dose. Results show that the importance of parametric uncertainty reduction varies according to the temporal dynamics of the lindane plume. The approach could be used for any chemical to aid decision makers to better allocate resources towards reducing uncertainty.

  8. A dynamic appearance descriptor approach to facial actions temporal modeling

    NARCIS (Netherlands)

    Jiang, Bihan; Valstar, Michel; Martinez, Brais; Pantic, Maja

    Both the configuration and the dynamics of facial expressions are crucial for the interpretation of human facial behavior. Yet to date, the vast majority of reported efforts in the field either do not take the dynamics of facial expressions into account, or focus only on prototypic facial

  9. Temporal dynamics of figure-ground segregation in human vision.

    Science.gov (United States)

    Neri, Peter; Levi, Dennis M

    2007-01-01

    The segregation of figure from ground is arguably one of the most fundamental operations in human vision. Neural signals reflecting this operation appear in cortex as early as 50 ms and as late as 300 ms after presentation of a visual stimulus, but it is not known when these signals are used by the brain to construct the percepts of figure and ground. We used psychophysical reverse correlation to identify the temporal window for figure-ground signals in human perception and found it to lie within the range of 100-160 ms. Figure enhancement within this narrow temporal window was transient rather than sustained as may be expected from measurements in single neurons. These psychophysical results prompt and guide further electrophysiological studies.

  10. Temporal dynamics of a subtropical urban forest in San Juan, Puerto Rico, 2001-2010

    Science.gov (United States)

    J. M. Tucker Lima; C. L. Staudhammer; T. J. Brandeis; F. J. Escobedo; W. Zipperer

    2013-01-01

    Several studies report urban tree growth and mortality rates as well as species composition, structural dynamics, and other characteristics of urban forests in mostly temperate, inland urban areas. Temporal dynamics of urban forests in subtropical and tropical forest regions are, until now, little explored and represent a new and important direction for study and...

  11. Spatio-temporal cell dynamics in tumour spheroid irradiation

    International Nuclear Information System (INIS)

    Kempf, H.; Bleicher, M.; Meyer-Hermann, M.; Kempf, H.; Bleicher, M.; Kempf, H.; Meyer-Hermann, M.

    2010-01-01

    Multicellular tumour spheroids are realistic in vitro systems in radiation research that integrate cell-cell interaction and cell cycle control by factors in the medium. The dynamic reaction inside a tumour spheroid triggered by radiation is not well understood. Of special interest is the amount of cell cycle synchronization which could be triggered by irradiation, since this would allow follow-up irradiations to exploit the increased sensitivity of certain cell cycle phases. In order to investigate these questions we need to support irradiation experiments with mathematical models. In this article a new model is introduced combining the dynamics of tumour growth and irradiation treatments. The tumour spheroid growth is modelled using an agent-based Delaunay/Voronoi hybrid model in which the cells are represented by weighted dynamic vertices. Cell properties like full cell cycle dynamics are included. In order to be able to distinguish between different cell reactions in response to irradiation quality we introduce a probabilistic model for damage dynamics. The overall cell survival from this model is in agreement with predictions from the linear-quadratic model. Our model can describe the growth of avascular tumour spheroids in agreement to experimental results. Using the probabilistic model for irradiation damage dynamics the classic 'four Rs' of radiotherapy can be studied in silico. We found a pronounced reactivation of the tumour spheroid in response to irradiation. A majority of the surviving cells is synchronized in their cell cycle progression after irradiation. The cell synchronization could be actively triggered and should be exploited in an advanced fractionation scheme. Thus it has been demonstrated that our model could be used to understand the dynamics of tumour growth after irradiation and to propose optimized fractionation schemes in cooperation with experimental investigations. (authors)

  12. Spatial and temporal infiltration dynamics during managed aquifer recharge.

    Science.gov (United States)

    Racz, Andrew J; Fisher, Andrew T; Schmidt, Calla M; Lockwood, Brian S; Los Huertos, Marc

    2012-01-01

    Natural groundwater recharge is inherently difficult to quantify and predict, largely because it comprises a series of processes that are spatially distributed and temporally variable. Infiltration ponds used for managed aquifer recharge (MAR) provide an opportunity to quantify recharge processes across multiple scales under semi-controlled conditions. We instrumented a 3-ha MAR infiltration pond to measure and compare infiltration patterns determined using whole-pond and point-specific methods. Whole-pond infiltration was determined by closing a transient water budget (accounting for inputs, outputs, and changes in storage), whereas point-specific infiltration rates were determined using heat as a tracer and time series analysis at eight locations in the base of the pond. Whole-pond infiltration, normalized for wetted area, rose rapidly to more than 1.0 m/d at the start of MAR operations (increasing as pond stage rose), was sustained at high rates for the next 40 d, and then decreased to less than 0.1 m/d by the end of the recharge season. Point-specific infiltration rates indicated high spatial and temporal variability, with the mean of measured values generally being lower than rates indicated by whole-pond calculations. Colocated measurements of head gradients within saturated soils below the pond were combined with infiltration rates to calculate soil hydraulic conductivity. Observations indicate a brief period of increasing saturated hydraulic conductivity, followed by a decrease of one to two orders of magnitude during the next 50 to 75 d. Locations indicating the most rapid infiltration shifted laterally during MAR operation, and we suggest that infiltration may function as a "variable source area" processes, conceptually similar to catchment runoff. © 2011, The Author(s). Ground Water © 2011, National Ground Water Association.

  13. Dynamic imaging in mild traumatic brain injury: support for the theory of medial temporal vulnerability.

    Science.gov (United States)

    Umile, Eric M; Sandel, M Elizabeth; Alavi, Abass; Terry, Charles M; Plotkin, Rosette C

    2002-11-01

    To determine whether patients with mild traumatic brain injury (TBI) and persistent postconcussive symptoms have evidence of temporal lobe injury on dynamic imaging. Case series. An academic medical center. Twenty patients with a clinical diagnosis of mild TBI and persistent postconcussive symptoms were referred for neuropsychologic evaluation and dynamic imaging. Fifteen (75%) had normal magnetic resonance imaging (MRI) and/or computed tomography (CT) scans at the time of injury. Neuropsychologic testing, positron-emission tomography (PET), and single-photon emission-computed tomography (SPECT). Temporal lobe findings on static imaging (MRI, CT) and dynamic imaging (PET, SPECT); neuropsychologic test findings on measures of verbal and visual memory. Testing documented neurobehavioral deficits in 19 patients (95%). Dynamic imaging documented abnormal findings in 18 patients (90%). Fifteen patients (75%) had temporal lobe abnormalities on PET and SPECT (primarily in medial temporal regions); abnormal findings were bilateral in 10 patients (50%) and unilateral in 5 (25%). Six patients (30%) had frontal abnormalities, and 8 (40%) had nonfrontotemporal abnormalities. Correlations between neuropsychologic testing and dynamic imaging could be established but not consistently across the whole group. Patients with mild TBI and persistent postconcussive symptoms have a high incidence of temporal lobe injury (presumably involving the hippocampus and related structures), which may explain the frequent finding of memory disorders in this population. The abnormal temporal lobe findings on PET and SPECT in humans may be analogous to the neuropathologic evidence of medial temporal injury provided by animal studies after mild TBI. Copyright 2002 by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation

  14. Spatio-temporal dynamics of a pulsed microwave argon plasma: ignition and afterglow

    International Nuclear Information System (INIS)

    Carbone, Emile; Sadeghi, Nader; Vos, Erik; Hübner, Simon; Van Veldhuizen, Eddie; Van Dijk, Jan; Nijdam, Sander; Kroesen, Gerrit

    2015-01-01

    In this paper, a detailed investigation of the spatio-temporal dynamics of a pulsed microwave plasma is presented. The plasma is ignited inside a dielectric tube in a repetitively pulsed regime at pressures ranging from 1 up to 100 mbar with pulse repetition frequencies from 200 Hz up to 500 kHz. Various diagnostic techniques are employed to obtain the main plasma parameters both spatially and with high temporal resolution. Thomson scattering is used to obtain the electron density and mean electron energy at fixed positions in the dielectric tube. The temporal evolution of the two resonant and two metastable argon 4s states are measured by laser diode absorption spectroscopy. Nanosecond time-resolved imaging of the discharge allows us to follow the spatio-temporal evolution of the discharge with high temporal and spatial resolution. Finally, the temporal evolution of argon 4p and higher states is measured by optical emission spectroscopy. The combination of these various diagnostics techniques gives deeper insight on the plasma dynamics during pulsed microwave plasma operation from low to high pressure regimes. The effects of the pulse repetition frequency on the plasma ignition dynamics are discussed and the plasma-off time is found to be the relevant parameter for the observed ignition modes. Depending on the delay between two plasma pulses, the dynamics of the ionization front are found to be changing dramatically. This is also reflected in the dynamics of the electron density and temperature and argon line emission from the plasma. On the other hand, the (quasi) steady state properties of the plasma are found to depend only weakly on the pulse repetition frequency and the afterglow kinetics present an uniform spatio-temporal behavior. However, compared to continuous operation, the time-averaged metastable and resonant state 4s densities are found to be significantly larger around a few kHz pulsing frequency. (paper)

  15. Maternal Caregiving Moderates the Relation between Temperamental Fear and Social Behavior with Peers

    Science.gov (United States)

    Penela, Elizabeth C.; Henderson, Heather A.; Hane, Amie A.; Ghera, Melissa M.; Fox, Nathan A.

    2012-01-01

    Temperament works in combination with a child's environment to influence early socioemotional development. We examined whether maternal caregiving behavior at infant age 9 months moderated the relation between infant temperamental fear (9 months) and observations of children's social behavior with an unfamiliar peer at age 2 in a typically…

  16. Exploring the relation between childhood trauma, temperamental traits and mindfulness in borderline personality disorder.

    Science.gov (United States)

    Elices, Matilde; Pascual, Juan C; Carmona, Cristina; Martín-Blanco, Ana; Feliu-Soler, Albert; Ruiz, Elisabet; Gomà-I-Freixanet, Montserrat; Pérez, Víctor; Soler, Joaquim

    2015-07-29

    Deficits in mindfulness-related capacities have been described in borderline personality disorder (BPD). However, little research has been conducted to explore which factors could explain these deficits. This study assesses the relationship between temperamental traits and childhood maltreatment with mindfulness in BPD. A total of 100 individuals diagnosed with BPD participated in the study. Childhood maltreatment was assessed using the Childhood Trauma Questionnaire (CTQ-SF), temperamental traits were assessed using the Zuckerman-Khulman Personality Questionnaire (ZKPQ), and mindfulness capabilities were evaluated with the Five Facet Mindfulness Questionnaire (FFMQ). Hierarchical regression analyses were performed including only those CTQ-SF and ZKPQ subscales that showed simultaneous significant correlations with mindfulness facets. Results indicated that neuroticism and sexual abuse were predictors of acting with awareness; and neuroticism, impulsiveness and sexual abuse were significant predictors of non-judging. Temperamental traits did not have a moderator effect on the relationship between childhood sexual abuse and mindfulness facets. These results provide preliminary evidence for the effects of temperamental traits and childhood trauma on mindfulness capabilities in BPD individuals. Further studies are needed to better clarify the impact of childhood traumatic experiences on mindfulness capabilities and to determine the causal relations between these variables.

  17. Emotional eating and temperamental traits in Eating Disorders: A dimensional approach.

    Science.gov (United States)

    Rotella, Francesco; Mannucci, Edoardo; Gemignani, Sara; Lazzeretti, Lisa; Fioravanti, Giulia; Ricca, Valdo

    2018-03-23

    Growing evidence shows that temperamental features and emotional dysregulation are linked to Eating Disorders (EDs). Aim of this study was to explore the possible relationship between temperament and emotional eating (EE) from a dimensional standpoint, and the association of specific temperamental dimensions with overeating triggered by specific emotions. We enrolled 253 women with Anorexia Nervosa, Bulimia Nervosa and Binge Eating Disorder. Of those, 189 (74.7%), 73 (28.8%), and 80 (31.6%) reported binge eating, purging, or restrictive behaviors, respectively (the categories are not mutually exclusive). Participants completed the Emotional Eating Scale (EES), the Temperament and Character Inventory, the Eating Disorder Examination Questionnaire (EDE-Q) and the Symptom Checklist 90-Revised (SCL-90-R). Higher Persistence scores were found in the Restriction group, while the Binge group reported lower Persistence and higher Novelty Seeking scores. The Purge group showed lower Reward Dependence, Self Directedness and Cooperativeness scores. Patients with Purge also reported lower BMI and higher scores on EDE-Q restriction and eating concern subscales as well as higher scores for all SCL 90-R subscales. Patterns of association between temperamental traits and specific emotions were found in each group. Therefore, some temperamental features could be considered predictors of specific associations between emotions and the tendency to eat. Copyright © 2018. Published by Elsevier B.V.

  18. Executive Function and Temperamental Fear Concurrently Predict Deception in School-Aged Children

    Science.gov (United States)

    Babkirk, Sarah; Saunders, Lauren V.; Solomon, Beylul; Kessel, Ellen M.; Crossman, Angela; Gokhan, Nurper; Dennis, Tracy A.

    2015-01-01

    The decision to intentionally withhold truthful information, or deception, is a key component of moral development and may be a precursor to more serious anti-social tendencies. Two factors, executive function (EF) and temperamental fear are each thought to influence childhood deception. Few studies, however, have explored deception in relation to…

  19. Temperamental, Parental, and Contextual Contributors to Early-Emerging Internalizing Problems: A New Integrative Analysis Approach

    Science.gov (United States)

    Mills, Rosemary S. L.; Hastings, Paul D.; Helm, Jonathan; Serbin, Lisa A.; Etezadi, Jamshid; Stack, Dale M.; Schwartzman, Alex E.; Li, Hai Hong

    2012-01-01

    This study evaluated a comprehensive model of factors associated with internalizing problems (IP) in early childhood, hypothesizing direct, mediated, and moderated pathways linking child temperamental inhibition, maternal overcontrol and rejection, and contextual stressors to IP. In a novel approach, three samples were integrated to form a large…

  20. Contributions of Child's Physiology and Maternal Behavior to Children's Trajectories of Temperamental Reactivity

    Science.gov (United States)

    Blandon, Alysia Y.; Calkins, Susan D.; Keane, Susan P.; O'brien, Marion

    2010-01-01

    Trajectories of children's temperamental reactivity (negative affectivity and surgency) were examined in a community sample of 370 children across the ages of 4 to 7 with hierarchical linear modeling. Children's physiological reactivity (respiratory sinus arrhythmia [RSA]), physiological regulation ([delta]RSA), and maternal parenting behavior…

  1. Urbanization Changes the Temporal Dynamics of Nutrients and Water Chemistry

    Science.gov (United States)

    Steele, M.; Badgley, B.

    2017-12-01

    Recent studies find that urban development alters the seasonal dynamics of nutrient concentrations, where the highest concentrations of nitrogen occurred during the winter in urban watersheds, rather than the summer. However, the effects of urbanization on the seasonal concentrations of other nutrients and chemical components is unknown. Therefore, to determine how urbanization changes the seasonal dynamics, once a week we measured concentrations of dissolved organic carbon (DOC), nutrients (NO3, DON, TN, PO4), base cations (Ca, Mg, Na, K), anions (F, Cl, SO4), pH, sediment, temperature, conductivity, and dissolved oxygen (DO) of nine urban, agricultural, and minimally developed watersheds in southwest Virginia, USA. We found that urbanization disrupted the seasonal dynamics of all metrics, except DON, PO4, Ca, sediment, and DO, where some shifted to high concentrations during the winter (Cl, conductivity), highs during late winter or spring (DOC, Na), a season low (TN, SO4, NO3) or high (NH4) during the summer, or remained more constant throughout the year compared to the reference watersheds (Mg, K, pH). The complex changes in seasonal dynamics coincide with a decoupling of common correlations between constituents; for example, DO and NO3 are negatively correlated in reference watersheds (NO3 increases, DO decreases), but positively correlated in urban watersheds. These results suggest that as watersheds become more intensely developed, the influence of natural drivers like temperature and vegetation become steadily overcome by the influence of urban drivers like deicing salts and wastewater leakage, which exert increasing control of seasonal water quality and aquatic habitat.

  2. Spatio-temporal Dynamics and Mechanisms of Stress Granule Assembly.

    Directory of Open Access Journals (Sweden)

    Daisuke Ohshima

    2015-06-01

    Full Text Available Stress granules (SGs are non-membranous cytoplasmic aggregates of mRNAs and related proteins, assembled in response to environmental stresses such as heat shock, hypoxia, endoplasmic reticulum (ER stress, chemicals (e.g. arsenite, and viral infections. SGs are hypothesized as a loci of mRNA triage and/or maintenance of proper translation capacity ratio to the pool of mRNAs. In brain ischemia, hippocampal CA3 neurons, which are resilient to ischemia, assemble SGs. In contrast, CA1 neurons, which are vulnerable to ischemia, do not assemble SGs. These results suggest a critical role SG plays in regards to cell fate decisions. Thus SG assembly along with its dynamics should determine the cell fate. However, the process that exactly determines the SG assembly dynamics is largely unknown. In this paper, analyses of experimental data and computer simulations were used to approach this problem. SGs were assembled as a result of applying arsenite to HeLa cells. The number of SGs increased after a short latent period, reached a maximum, then decreased during the application of arsenite. At the same time, the size of SGs grew larger and became localized at the perinuclear region. A minimal mathematical model was constructed, and stochastic simulations were run to test the modeling. Since SGs are discrete entities as there are only several tens of them in a cell, commonly used deterministic simulations could not be employed. The stochastic simulations replicated observed dynamics of SG assembly. In addition, these stochastic simulations predicted a gamma distribution relative to the size of SGs. This same distribution was also found in our experimental data suggesting the existence of multiple fusion steps in the SG assembly. Furthermore, we found that the initial steps in the SG assembly process and microtubules were critical to the dynamics. Thus our experiments and stochastic simulations presented a possible mechanism regulating SG assembly.

  3. Temporal dynamics and leaf trait variability in Neotropical dry forests

    Science.gov (United States)

    Hesketh, Michael Sean

    This thesis explores the variability of leaf traits resulting from changes in season, ecosystem successional stage, and site characteristics. In chapter two, I present a review of the use of remote sensing analysis for the evaluation of Neotropical dry forests. Here, I stress the conclusion, drawn from studies on land cover characterization, biodiversity assessment, and evaluation of forest structural characteristics, that addressing temporal variability in spectral properties is an essential element in the monitoring of these ecosystems. Chapter three describes the effect of wet-dry seasonality on spectral classification of tree and liana species. Highly accurate classification (> 80%) was possible using data from either the wet or dry season. However, this accuracy decreased by a factor of ten when data from the wet season was classified using an algorithm trained on the dry, or vice versa. I also address the potential creation of a spectral taxonomy of species, but found that any clustering based on spectral properties resulted in markedly different arrangements in the wet and dry seasons. In chapter 4, I address the variation present in both physical and spectral leaf traits according to changes in forest successional stage at dry forest sites in Mexico and Costa Rica. I found significant differences in leaf traits between successional stages, but more strongly so in Costa Rica. This variability deceased the accuracy of spectral classification of tree species by a factor of four when classifying data using an algorithm trained on a different successional stage. Chapter 5 shows the influence of seasonality and succession on trait variability in Mexico. Differences in leaf traits between successional stages were found to be greater during the dry season, but were sufficient in both seasons to negatively influence spectral classification of tree species. Throughout this thesis, I show clear and unambiguous evidence of the variability of key physical and spectral

  4. Annual and diurnal african biomass burning temporal dynamics

    Directory of Open Access Journals (Sweden)

    G. Roberts

    2009-05-01

    Full Text Available Africa is the single largest continental source of biomass burning emissions. Here we conduct the first analysis of one full year of geostationary active fire detections and fire radiative power data recorded over Africa at 15-min temporal interval and a 3 km sub-satellite spatial resolution by the Spinning Enhanced Visible and Infrared Imager (SEVIRI imaging radiometer onboard the Meteosat-8 satellite. We use these data to provide new insights into the rates and totals of open biomass burning over Africa, particularly into the extremely strong seasonal and diurnal cycles that exist across the continent. We estimate peak daily biomass combustion totals to be 9 and 6 million tonnes of fuel per day in the northern and southern hemispheres respectively, and total fuel consumption between February 2004 and January 2005 is estimated to be at least 855 million tonnes. Analysis is carried out with regard to fire pixel temporal persistence, and we note that the majority of African fires are detected only once in consecutive 15 min imaging slots. An investigation of the variability of the diurnal fire cycle is carried out with respect to 20 different land cover types, and whilst differences are noted between land covers, the fire diurnal cycle characteristics for most land cover type are very similar in both African hemispheres. We compare the Fire Radiative Power (FRP derived biomass combustion estimates to burned-areas, both at the scale of individual fires and over the entire continent at a 1-degree scale. Fuel consumption estimates are found to be less than 2 kg/m2 for all land cover types noted to be subject to significant fire activity, and for savanna grasslands where literature values are commonly reported the FRP-derived median fuel consumption estimate of 300 g/m2 is well within commonly quoted values. Meteosat-derived FRP data of the type presented here is now available freely to interested users continuously and in near

  5. Temporal dynamics of all-optical switching in Photonic Crystal Cavity

    DEFF Research Database (Denmark)

    Colman, Pierre; Heuck, Mikkel; Yu, Yi

    2014-01-01

    The temporal dynamics of all-optical switching has been investigated in a Photonic Crystal Cavity with a 150fs-40aJ/pulse resolution. This allowed observing for the first time effects like pulse reshaping, pulse delay and intra-cavity Four-Wave-Mixing.......The temporal dynamics of all-optical switching has been investigated in a Photonic Crystal Cavity with a 150fs-40aJ/pulse resolution. This allowed observing for the first time effects like pulse reshaping, pulse delay and intra-cavity Four-Wave-Mixing....

  6. STABILITY AND DYNAMICS OF SPATIO-TEMPORAL STRUCTURES

    Energy Technology Data Exchange (ETDEWEB)

    Hermann Riecke

    2005-10-21

    This document constitutes the final report for the grant. It provides a complete list of publications and presentations that arose from the project as well as a brief description of the highlights of the research results. The research funded by this grant has provided insights into the spontaneous formation of structures of increasing complexity in systems driven far from thermodynamic equilibrium. A classic example of such a system is thermally driven convection in a horizontal fluid layer. Highlights of the research are: (1) explanation of the localized traveling wave pulses observed in binary-mixture convection, (2) explanation of the localized waves in electroconvection, (3) introduction of a new diagnostics for spatially and temporally chaotic states, which is based on the statistics of defect trajectories, (4) prediction of complex states in thermally driven convection in rotating systems. Additional contributions provided insight into the localization mechanism for oscillons, the prediction of a new localization mechanism for traveling waves based on a resonant periodic forcing, and an analysis of the stability of quasi-periodic patterns.

  7. Practical considerations for high spatial and temporal resolution dynamic transmission electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Armstrong, Michael R. [Materials Science and Technology Division, Chemistry and Materials Science Directorate, Lawrence Livermore National Laboratory, P.O. Box 808, L-356, Livermore, CA 94550 (United States)], E-mail: armstrong30@llnl.gov; Boyden, Ken [Materials Science and Technology Division, Chemistry and Materials Science Directorate, Lawrence Livermore National Laboratory, P.O. Box 808, L-356, Livermore, CA 94550 (United States); Browning, Nigel D. [Materials Science and Technology Division, Chemistry and Materials Science Directorate, Lawrence Livermore National Laboratory, P.O. Box 808, L-356, Livermore, CA 94550 (United States); Department of Chemical Engineering and Materials Science, University of California-Davis, One Shields Avenue, Davis, CA 95616 (United States); Campbell, Geoffrey H.; Colvin, Jeffrey D.; De Hope, William J.; Frank, Alan M. [Materials Science and Technology Division, Chemistry and Materials Science Directorate, Lawrence Livermore National Laboratory, P.O. Box 808, L-356, Livermore, CA 94550 (United States); Gibson, David J.; Hartemann, Fred [N Division, Physics and Advanced Technologies Directorate, Lawrence Livermore National Laboratory, P.O. Box 808, L-280, Livermore, CA 94550 (United States); Kim, Judy S. [Materials Science and Technology Division, Chemistry and Materials Science Directorate, Lawrence Livermore National Laboratory, P.O. Box 808, L-356, Livermore, CA 94550 (United States); Department of Chemical Engineering and Materials Science, University of California-Davis, One Shields Avenue, Davis, CA 95616 (United States); King, Wayne E.; La Grange, Thomas B.; Pyke, Ben J.; Reed, Bryan W.; Shuttlesworth, Richard M.; Stuart, Brent C.; Torralva, Ben R. [Materials Science and Technology Division, Chemistry and Materials Science Directorate, Lawrence Livermore National Laboratory, P.O. Box 808, L-356, Livermore, CA 94550 (United States)

    2007-04-15

    Although recent years have seen significant advances in the spatial resolution possible in the transmission electron microscope (TEM), the temporal resolution of most microscopes is limited to video rate at best. This lack of temporal resolution means that our understanding of dynamic processes in materials is extremely limited. High temporal resolution in the TEM can be achieved, however, by replacing the normal thermionic or field emission source with a photoemission source. In this case the temporal resolution is limited only by the ability to create a short pulse of photoexcited electrons in the source, and this can be as short as a few femtoseconds. The operation of the photo-emission source and the control of the subsequent pulse of electrons (containing as many as 5x10{sup 7} electrons) create significant challenges for a standard microscope column that is designed to operate with a single electron in the column at any one time. In this paper, the generation and control of electron pulses in the TEM to obtain a temporal resolution <10{sup -6} s will be described and the effect of the pulse duration and current density on the spatial resolution of the instrument will be examined. The potential of these levels of temporal and spatial resolution for the study of dynamic materials processes will also be discussed.

  8. Practical considerations for high spatial and temporal resolution dynamic transmission electron microscopy

    International Nuclear Information System (INIS)

    Armstrong, Michael R.; Boyden, Ken; Browning, Nigel D.; Campbell, Geoffrey H.; Colvin, Jeffrey D.; De Hope, William J.; Frank, Alan M.; Gibson, David J.; Hartemann, Fred; Kim, Judy S.; King, Wayne E.; La Grange, Thomas B.; Pyke, Ben J.; Reed, Bryan W.; Shuttlesworth, Richard M.; Stuart, Brent C.; Torralva, Ben R.

    2007-01-01

    Although recent years have seen significant advances in the spatial resolution possible in the transmission electron microscope (TEM), the temporal resolution of most microscopes is limited to video rate at best. This lack of temporal resolution means that our understanding of dynamic processes in materials is extremely limited. High temporal resolution in the TEM can be achieved, however, by replacing the normal thermionic or field emission source with a photoemission source. In this case the temporal resolution is limited only by the ability to create a short pulse of photoexcited electrons in the source, and this can be as short as a few femtoseconds. The operation of the photo-emission source and the control of the subsequent pulse of electrons (containing as many as 5x10 7 electrons) create significant challenges for a standard microscope column that is designed to operate with a single electron in the column at any one time. In this paper, the generation and control of electron pulses in the TEM to obtain a temporal resolution -6 s will be described and the effect of the pulse duration and current density on the spatial resolution of the instrument will be examined. The potential of these levels of temporal and spatial resolution for the study of dynamic materials processes will also be discussed

  9. Temporal Expectations Guide Dynamic Prioritization in Visual Working Memory through Attenuated α Oscillations.

    Science.gov (United States)

    van Ede, Freek; Niklaus, Marcel; Nobre, Anna C

    2017-01-11

    Although working memory is generally considered a highly dynamic mnemonic store, popular laboratory tasks used to understand its psychological and neural mechanisms (such as change detection and continuous reproduction) often remain relatively "static," involving the retention of a set number of items throughout a shared delay interval. In the current study, we investigated visual working memory in a more dynamic setting, and assessed the following: (1) whether internally guided temporal expectations can dynamically and reversibly prioritize individual mnemonic items at specific times at which they are deemed most relevant; and (2) the neural substrates that support such dynamic prioritization. Participants encoded two differently colored oriented bars into visual working memory to retrieve the orientation of one bar with a precision judgment when subsequently probed. To test for the flexible temporal control to access and retrieve remembered items, we manipulated the probability for each of the two bars to be probed over time, and recorded EEG in healthy human volunteers. Temporal expectations had a profound influence on working memory performance, leading to faster access times as well as more accurate orientation reproductions for items that were probed at expected times. Furthermore, this dynamic prioritization was associated with the temporally specific attenuation of contralateral α (8-14 Hz) oscillations that, moreover, predicted working memory access times on a trial-by-trial basis. We conclude that attentional prioritization in working memory can be dynamically steered by internally guided temporal expectations, and is supported by the attenuation of α oscillations in task-relevant sensory brain areas. In dynamic, everyday-like, environments, flexible goal-directed behavior requires that mental representations that are kept in an active (working memory) store are dynamic, too. We investigated working memory in a more dynamic setting than is conventional

  10. The interplay between perceptual organization and object recognition: Temporal dynamics and neuropsychology

    OpenAIRE

    Torfs, Katrien

    2012-01-01

    The ease and efficiency with which we perceive objects in daily life masks the complexity of the processes involved. The main goal of my doctoral research was to enhance our understanding of the complex interplay between perceptual organization and object recognition. To this end, we investigated the dynamic interplay between different component processes of object recognition, and their temporal dynamics. In the first part of this thesis, I present three behavioral studies focusing on the ro...

  11. The Temporal Signature of Memories: Identification of a General Mechanism for Dynamic Memory Replay in Humans

    Science.gov (United States)

    Michelmann, Sebastian; Bowman, Howard; Hanslmayr, Simon

    2016-01-01

    Reinstatement of dynamic memories requires the replay of neural patterns that unfold over time in a similar manner as during perception. However, little is known about the mechanisms that guide such a temporally structured replay in humans, because previous studies used either unsuitable methods or paradigms to address this question. Here, we overcome these limitations by developing a new analysis method to detect the replay of temporal patterns in a paradigm that requires participants to mentally replay short sound or video clips. We show that memory reinstatement is accompanied by a decrease of low-frequency (8 Hz) power, which carries a temporal phase signature of the replayed stimulus. These replay effects were evident in the visual as well as in the auditory domain and were localized to sensory-specific regions. These results suggest low-frequency phase to be a domain-general mechanism that orchestrates dynamic memory replay in humans. PMID:27494601

  12. The Temporal Signature of Memories: Identification of a General Mechanism for Dynamic Memory Replay in Humans.

    Directory of Open Access Journals (Sweden)

    Sebastian Michelmann

    2016-08-01

    Full Text Available Reinstatement of dynamic memories requires the replay of neural patterns that unfold over time in a similar manner as during perception. However, little is known about the mechanisms that guide such a temporally structured replay in humans, because previous studies used either unsuitable methods or paradigms to address this question. Here, we overcome these limitations by developing a new analysis method to detect the replay of temporal patterns in a paradigm that requires participants to mentally replay short sound or video clips. We show that memory reinstatement is accompanied by a decrease of low-frequency (8 Hz power, which carries a temporal phase signature of the replayed stimulus. These replay effects were evident in the visual as well as in the auditory domain and were localized to sensory-specific regions. These results suggest low-frequency phase to be a domain-general mechanism that orchestrates dynamic memory replay in humans.

  13. Brazilian Amazon Roads and Parks: Temporal & Spatial Deforestation Dynamics

    Science.gov (United States)

    Pfaff, A.; Robalino, J.

    2011-12-01

    Heterogeneous Forest Impacts of Transport Infrastructure: spatial frontier dynamics & impacts of Brazilian Amazon road changes Prior research on road impacts has almost completely ignored heterogeneity of impacts and as a result both empirically understated potential impact and missed policy potential. We note von Thunen's model suggests not only heterogeneity with distance from market but also specifically road impacts rising then falling with distance ('non-monoThunicity') Endogenous development and partial adjustment dynamics support this for the short run. Causal effects result from studying Brazilian Amazon deforestation (1976-87, 2000-04) using matching for short-run responses to lagged new roads changes (1968-75, 1985-00). We show the critical role of prior development, proxied by 1968 and 1985 road distances, for which exact matching addresses development trends and transforms impact estimates. Splitting the sample on this measure finds confirmation of the nonmonotonic predictions: new road impacts are relatively low if a prior road was close, such that prior transport access and endogenous development dynamics compete with the new road for influence, but also if a prior road was far, since first-decade adjustment in pristine areas is limited; yet in between these bounds, investments immediately raise deforestation significantly. This pattern helps to explain lower estimates within research on a single average impact. It suggests potential for REDD if a country chooses to shift its spatial transport networks. Protected Areas & Brazilian Amazon Deforestation: modeling and testing the impacts of varied PA strategies We model and then estimate the impacts of multiple types of protected areas upon 2000 - 2004 deforestation in the Brazilian Amazon. Our modeling starts with federal versus state objectives and predicts differences in both choice and implementation of each PA strategy that we examine. Our empirical examination brings not only breakdowns sufficient

  14. A Model of the Temporal Dynamics of Knowledge Brokerage in Sustainable Development

    Science.gov (United States)

    Hukkinen, Janne I.

    2016-01-01

    I develop a conceptual model of the temporal dynamics of knowledge brokerage for sustainable development. Brokerage refers to efforts to make research and policymaking more accessible to each other. The model enables unbiased and systematic consideration of knowledge brokerage as part of policy evolution. The model is theoretically grounded in…

  15. Temporal dynamics of motor cortex excitability during perception of natural emotional scenes

    NARCIS (Netherlands)

    Borgomaneri, Sara; Gazzola, Valeria; Avenanti, Alessio

    2014-01-01

    Although it is widely assumed that emotions prime the body for action, the effects of visual perception of natural emotional scenes on the temporal dynamics of the human motor system have scarcely been investigated. Here, we used single-pulse transcranial magnetic stimulation (TMS) to assess motor

  16. The Temporal Dynamics of Spoken Word Recognition in Adverse Listening Conditions

    Science.gov (United States)

    Brouwer, Susanne; Bradlow, Ann R.

    2016-01-01

    This study examined the temporal dynamics of spoken word recognition in noise and background speech. In two visual-world experiments, English participants listened to target words while looking at four pictures on the screen: a target (e.g. "candle"), an onset competitor (e.g. "candy"), a rhyme competitor (e.g.…

  17. An assessment of the temporal dynamics of moral decisions

    Directory of Open Access Journals (Sweden)

    Gregory J. Koop

    2013-09-01

    Full Text Available In the domain of moral decision making, models in which emotion and deliberation constitute competing dual-systems have become increasingly popular. Currently, the favored explanation of this interaction is what Evans (2008 termed a ``default-interventionist'' (DI process where moral decisions are the result of a prepotent emotional response, which can be overridden with substantial deliberative effort. Although this ``emotion-then-deliberation'' sequence is often assumed, existing methods have lacked the requisite process resolution to clearly depict the nature of this interaction. The present work utilized continuous mouse tracking, or response dynamics, to develop and test predictions of these DI models of moral decision making. Study 1 utilized previously published moral dilemmas to validate the method for use with such complex stimuli. Although the data replicated typical choice and RT patterns, the process metrics provided by the response trajectories did not demonstrate the online preference reversals predicted by DI models. Study 2 utilized more rigorously constructed stimuli and an alternative presentation format to provide the strongest possible test of DI predictions, but again failed to show the predicted reversals. In summary, neither experiment provided data in accordance with the predictions of popular DI dual-systems models, which suggests that researchers should consider models allowing for concurrent activation of deliberative and emotional systems, or reconceptualize moral decisions within the typical multiattribute decision framework.

  18. Temporal dynamics of reward anticipation in the human brain.

    Science.gov (United States)

    Zhang, Yuanyuan; Li, Qi; Wang, Zhao; Liu, Xun; Zheng, Ya

    2017-09-01

    Reward anticipation is a complex process including cue evaluation, motor preparation, and feedback anticipation. The present study investigated whether these psychological processes were dissociable on neural dynamics in terms of incentive valence and approach motivation. We recorded EEG when participants were performing a monetary incentive delay task, and found a cue-P3 during the cue-evaluation stage, a contingent negative variation (CNV) during the motor-preparation stage, and a stimulus-preceding negativity (SPN) during the feedback-anticipation stage. Critically, both the cue-P3 and SPN exhibited an enhanced sensitivity to gain versus loss anticipation, which was not observed for the CNV. Moreover, both the cue-P3 and SPN, instead of the CNV, for gain anticipation selectively predicted the participants' approach motivation as measured in a following effort expenditure for rewards task, particularly when reward uncertainty was maximal. Together, these results indicate that reward anticipation consists of several sub-stages, each with distinct functional significance, thus providing implications for neuropsychiatric diseases characterized by dysfunction in anticipatory reward processing. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. An American termite in Paris: temporal colony dynamics.

    Science.gov (United States)

    Baudouin, Guillaume; Dedeine, Franck; Bech, Nicolas; Bankhead-Dronnet, Stéphanie; Dupont, Simon; Bagnères, Anne-Geneviève

    2017-12-01

    Termites of the genus Reticulitermes are widespread invaders, particularly in urban habitats. Their cryptic and subterranean lifestyle makes them difficult to detect, and we know little about their colony dynamics over time. In this study we examined the persistence of Reticulitermes flavipes (Kollar) colonies in the city of Paris over a period of 15 years. The aim was (1) to define the boundaries of colonies sampled within the same four areas over two sampling periods, (2) to determine whether the colonies identified during the first sampling period persisted to the second sampling period, and (3) to compare the results obtained when colonies were delineated using a standard population genetic approach versus a Bayesian clustering method that combined both spatial and genetic information. Herein, colony delineations were inferred from genetic differences at nine microsatellite loci and one mitochondrial locus. Four of the 18 identified colonies did not show significant differences in their genotype distributions between the two sampling periods. While allelic richness was low, making it hard to reliably distinguish colony family type, most colonies appeared to retain the same breeding structure over time. These large and expansive colonies showed an important ability to fuse (39% were mixed-family colonies), contained hundreds of reproductives and displayed evidence of isolation-by-distance, suggesting budding dispersal. These traits, which favor colony persistence over time, present a challenge for pest control efforts, which apply treatment locally. The other colonies showed significant differences, but we cannot exclude the possibility that their genotype distributions simply changed over time.

  20. Spatio-temporal reconstruction of brain dynamics from EEG with a Markov prior

    DEFF Research Database (Denmark)

    Hansen, Sofie Therese; Hansen, Lars Kai

    2016-01-01

    the functional dynamics of the brain. Solving the inverse problem of EEG is however highly ill-posed as there are many more potential locations of the EEG generators than EEG measurement points. Several well-known properties of brain dynamics can be exploited to alleviate this problem. More short ranging......Electroencephalography (EEG) can capture brain dynamics in high temporal resolution. By projecting the scalp EEG signal back to its origin in the brain also high spatial resolution can be achieved. Source localized EEG therefore has potential to be a very powerful tool for understanding...

  1. Reconstruction of tissue dynamics in the compressed breast using multiplexed measurements and temporal basis functions

    Science.gov (United States)

    Boverman, Gregory; Miller, Eric L.; Brooks, Dana H.; Fang, Qianqian; Carp, S. A.; Selb, J. J.; Boas, David A.

    2007-02-01

    In the course of our experiments imaging the compressed breast in conjunction with digital tomosynthesis, we have noted that significant changes in tissue optical properties, on the order of 5%, occur during our imaging protocol. These changes seem to consistent with changes both in total Hemoglobin concentration as well as in oxygen saturation, as was the case for our standalone breast compression study, which made use of reflectance measurements. Simulation experiments show the importance of taking into account the temporal dynamics in the image reconstruction, and demonstrate the possibility of imaging the spatio-temporal dynamics of oxygen saturation and total Hemoglobin in the breast. In the image reconstruction, we make use of spatio-temporal basis functions, specifically a voxel basis for spatial imaging, and a cubic spline basis in time, and we reconstruct the spatio-temporal images using the entire data set simultaneously, making use of both absolute and relative measurements in the cost function. We have modified the sequence of sources used in our imaging acquisition protocol to improve our temporal resolution, and preliminary results are shown for normal subjects.

  2. Spatial and Temporal Dynamics and Value of Nature-Based Recreation, Estimated via Social Media.

    Science.gov (United States)

    Sonter, Laura J; Watson, Keri B; Wood, Spencer A; Ricketts, Taylor H

    2016-01-01

    Conserved lands provide multiple ecosystem services, including opportunities for nature-based recreation. Managing this service requires understanding the landscape attributes underpinning its provision, and how changes in land management affect its contribution to human wellbeing over time. However, evidence from both spatially explicit and temporally dynamic analyses is scarce, often due to data limitations. In this study, we investigated nature-based recreation within conserved lands in Vermont, USA. We used geotagged photographs uploaded to the photo-sharing website Flickr to quantify visits by in-state and out-of-state visitors, and we multiplied visits by mean trip expenditures to show that conserved lands contributed US $1.8 billion (US $0.18-20.2 at 95% confidence) to Vermont's tourism industry between 2007 and 2014. We found eight landscape attributes explained the pattern of visits to conserved lands; visits were higher in larger conserved lands, with less forest cover, greater trail density and more opportunities for snow sports. Some of these attributes differed from those found in other locations, but all aligned with our understanding of recreation in Vermont. We also found that using temporally static models to inform conservation decisions may have perverse outcomes for nature-based recreation. For example, static models suggest conserved land with less forest cover receive more visits, but temporally dynamic models suggest clearing forests decreases, rather than increases, visits to these sites. Our results illustrate the importance of understanding both the spatial and temporal dynamics of ecosystem services for conservation decision-making.

  3. Portraying Temporal Dynamics of Urban Spatial Divisions with Mobile Phone Positioning Data: A Complex Network Approach

    Directory of Open Access Journals (Sweden)

    Meng Zhou

    2016-12-01

    Full Text Available Spatial structure is a fundamental characteristic of cities that influences the urban functioning to a large extent. While administrative partitioning is generally done in the form of static spatial division, understanding a more temporally dynamic structure of the urban space would benefit urban planning and management immensely. This study makes use of a large-scale mobile phone positioning dataset to characterize the diurnal dynamics of the interaction-based urban spatial structure. To extract the temporally vibrant structure, spatial interaction networks at different times are constructed based on the movement connections of individuals between geographical units. Complex network community detection technique is applied to identify the spatial divisions as well as to quantify their temporal dynamics. Empirical analysis is conducted using data containing all user positions on a typical weekday in Shenzhen, China. Results are compared with official zoning and planned structure and indicate a certain degree of expansion in urban central areas and fragmentation in industrial suburban areas. A high level of variability in spatial divisions at different times of day is detected with some distinct temporal features. Peak and pre-/post-peak hours witness the most prominent fluctuation in spatial division indicating significant change in the characteristics of movements and activities during these periods of time. Findings of this study demonstrate great potential of large-scale mobility data in supporting intelligent spatial decision making and providing valuable knowledge to the urban planning sectors.

  4. Modeling Temporal Behavior in Large Networks: A Dynamic Mixed-Membership Model

    Energy Technology Data Exchange (ETDEWEB)

    Rossi, R; Gallagher, B; Neville, J; Henderson, K

    2011-11-11

    Given a large time-evolving network, how can we model and characterize the temporal behaviors of individual nodes (and network states)? How can we model the behavioral transition patterns of nodes? We propose a temporal behavior model that captures the 'roles' of nodes in the graph and how they evolve over time. The proposed dynamic behavioral mixed-membership model (DBMM) is scalable, fully automatic (no user-defined parameters), non-parametric/data-driven (no specific functional form or parameterization), interpretable (identifies explainable patterns), and flexible (applicable to dynamic and streaming networks). Moreover, the interpretable behavioral roles are generalizable, computationally efficient, and natively supports attributes. We applied our model for (a) identifying patterns and trends of nodes and network states based on the temporal behavior, (b) predicting future structural changes, and (c) detecting unusual temporal behavior transitions. We use eight large real-world datasets from different time-evolving settings (dynamic and streaming). In particular, we model the evolving mixed-memberships and the corresponding behavioral transitions of Twitter, Facebook, IP-Traces, Email (University), Internet AS, Enron, Reality, and IMDB. The experiments demonstrate the scalability, flexibility, and effectiveness of our model for identifying interesting patterns, detecting unusual structural transitions, and predicting the future structural changes of the network and individual nodes.

  5. A dynamic texture-based approach to recognition of facial actions and their temporal models.

    Science.gov (United States)

    Koelstra, Sander; Pantic, Maja; Patras, Ioannis

    2010-11-01

    In this work, we propose a dynamic texture-based approach to the recognition of facial Action Units (AUs, atomic facial gestures) and their temporal models (i.e., sequences of temporal segments: neutral, onset, apex, and offset) in near-frontal-view face videos. Two approaches to modeling the dynamics and the appearance in the face region of an input video are compared: an extended version of Motion History Images and a novel method based on Nonrigid Registration using Free-Form Deformations (FFDs). The extracted motion representation is used to derive motion orientation histogram descriptors in both the spatial and temporal domain. Per AU, a combination of discriminative, frame-based GentleBoost ensemble learners and dynamic, generative Hidden Markov Models detects the presence of the AU in question and its temporal segments in an input image sequence. When tested for recognition of all 27 lower and upper face AUs, occurring alone or in combination in 264 sequences from the MMI facial expression database, the proposed method achieved an average event recognition accuracy of 89.2 percent for the MHI method and 94.3 percent for the FFD method. The generalization performance of the FFD method has been tested using the Cohn-Kanade database. Finally, we also explored the performance on spontaneous expressions in the Sensitive Artificial Listener data set.

  6. A Temporal Domain Decomposition Algorithmic Scheme for Large-Scale Dynamic Traffic Assignment

    Directory of Open Access Journals (Sweden)

    Eric J. Nava

    2012-03-01

    This paper presents a temporal decomposition scheme for large spatial- and temporal-scale dynamic traffic assignment, in which the entire analysis period is divided into Epochs. Vehicle assignment is performed sequentially in each Epoch, thus improving the model scalability and confining the peak run-time memory requirement regardless of the total analysis period. A proposed self-turning scheme adaptively searches for the run-time-optimal Epoch setting during iterations regardless of the characteristics of the modeled network. Extensive numerical experiments confirm the promising performance of the proposed algorithmic schemes.

  7. Temperamental traits may be associated with medical students’ specialty preferences – pilot study

    Directory of Open Access Journals (Sweden)

    Agnieszka Pawełczyk

    2010-06-01

    Full Text Available Objective: This study was aimed at checking a hypothesis about a possible correlation between medical students’ temperamental traits and specialty preferences. Material and methods: The study was carried out among 202 students of the 6th year at the Medical University of Łódź in academic year 2008/2009. The examined group consisted of 140 women (69% and 62 men (31%. The average age of the students included into the study was 24.7 years (range: 23-29. The subjects were asked to fill in a questionnaire on demographic variables and the Formal Characteristics of BehaviourTemperament Inventory (FCB-TI by Zawadzki and Strelau. Results: The students taking part in the study preferred specialties in internal diseases (22%, surgery (18% and paediatrics (11%. Two point five percent of the students were indecisive in the specialty choice, 26% preferred surgical specialty and 71% – non-surgical specialty. Differences in temperamental traits were indicated between the students preferring different specialties. Students preferring surgery scored higher than those preferring internal medicine in Endurance (p=0.0036, d=0.63 and Activity (p=0.0292, d=0.63. Significantly higher average values were observed within two temperamental traits: Briskness (p=0.0083, d=0.5 and Endurance (p=0.0070, d=0.49 in students preferring surgical specialties, as compared to those choosing non-surgical specialties. Conclusions: Students’ preferring different medical specialties differ in temperamental traits. They obtained different results on the scales of Briskness, Endurance and Activity. The obtained results may be useful in vocational guidance within the choice of medical specialty.

  8. Estimating spatio-temporal dynamics of stream total phosphate concentration by soft computing techniques.

    Science.gov (United States)

    Chang, Fi-John; Chen, Pin-An; Chang, Li-Chiu; Tsai, Yu-Hsuan

    2016-08-15

    This study attempts to model the spatio-temporal dynamics of total phosphate (TP) concentrations along a river for effective hydro-environmental management. We propose a systematical modeling scheme (SMS), which is an ingenious modeling process equipped with a dynamic neural network and three refined statistical methods, for reliably predicting the TP concentrations along a river simultaneously. Two different types of artificial neural network (BPNN-static neural network; NARX network-dynamic neural network) are constructed in modeling the dynamic system. The Dahan River in Taiwan is used as a study case, where ten-year seasonal water quality data collected at seven monitoring stations along the river are used for model training and validation. Results demonstrate that the NARX network can suitably capture the important dynamic features and remarkably outperforms the BPNN model, and the SMS can effectively identify key input factors, suitably overcome data scarcity, significantly increase model reliability, satisfactorily estimate site-specific TP concentration at seven monitoring stations simultaneously, and adequately reconstruct seasonal TP data into a monthly scale. The proposed SMS can reliably model the dynamic spatio-temporal water pollution variation in a river system for missing, hazardous or costly data of interest. Copyright © 2016 Elsevier B.V. All rights reserved.

  9. MR-guided dynamic PET reconstruction with the kernel method and spectral temporal basis functions

    Science.gov (United States)

    Novosad, Philip; Reader, Andrew J.

    2016-06-01

    Recent advances in dynamic positron emission tomography (PET) reconstruction have demonstrated that it is possible to achieve markedly improved end-point kinetic parameter maps by incorporating a temporal model of the radiotracer directly into the reconstruction algorithm. In this work we have developed a highly constrained, fully dynamic PET reconstruction algorithm incorporating both spectral analysis temporal basis functions and spatial basis functions derived from the kernel method applied to a co-registered T1-weighted magnetic resonance (MR) image. The dynamic PET image is modelled as a linear combination of spatial and temporal basis functions, and a maximum likelihood estimate for the coefficients can be found using the expectation-maximization (EM) algorithm. Following reconstruction, kinetic fitting using any temporal model of interest can be applied. Based on a BrainWeb T1-weighted MR phantom, we performed a realistic dynamic [18F]FDG simulation study with two noise levels, and investigated the quantitative performance of the proposed reconstruction algorithm, comparing it with reconstructions incorporating either spectral analysis temporal basis functions alone or kernel spatial basis functions alone, as well as with conventional frame-independent reconstruction. Compared to the other reconstruction algorithms, the proposed algorithm achieved superior performance, offering a decrease in spatially averaged pixel-level root-mean-square-error on post-reconstruction kinetic parametric maps in the grey/white matter, as well as in the tumours when they were present on the co-registered MR image. When the tumours were not visible in the MR image, reconstruction with the proposed algorithm performed similarly to reconstruction with spectral temporal basis functions and was superior to both conventional frame-independent reconstruction and frame-independent reconstruction with kernel spatial basis functions. Furthermore, we demonstrate that a joint spectral

  10. Face processing regions are sensitive to distinct aspects of temporal sequence in facial dynamics.

    Science.gov (United States)

    Reinl, Maren; Bartels, Andreas

    2014-11-15

    Facial movement conveys important information for social interactions, yet its neural processing is poorly understood. Computational models propose that shape- and temporal sequence sensitive mechanisms interact in processing dynamic faces. While face processing regions are known to respond to facial movement, their sensitivity to particular temporal sequences has barely been studied. Here we used fMRI to examine the sensitivity of human face-processing regions to two aspects of directionality in facial movement trajectories. We presented genuine movie recordings of increasing and decreasing fear expressions, each of which were played in natural or reversed frame order. This two-by-two factorial design matched low-level visual properties, static content and motion energy within each factor, emotion-direction (increasing or decreasing emotion) and timeline (natural versus artificial). The results showed sensitivity for emotion-direction in FFA, which was timeline-dependent as it only occurred within the natural frame order, and sensitivity to timeline in the STS, which was emotion-direction-dependent as it only occurred for decreased fear. The occipital face area (OFA) was sensitive to the factor timeline. These findings reveal interacting temporal sequence sensitive mechanisms that are responsive to both ecological meaning and to prototypical unfolding of facial dynamics. These mechanisms are temporally directional, provide socially relevant information regarding emotional state or naturalness of behavior, and agree with predictions from modeling and predictive coding theory. Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.

  11. Laminar and Temporal Expression Dynamics of Coding and Noncoding RNAs in the Mouse Neocortex

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    Sofia Fertuzinhos

    2014-03-01

    Full Text Available The hallmark of the cerebral neocortex is its organization into six layers, each containing a characteristic set of cell types and synaptic connections. The transcriptional events involved in laminar development and function still remain elusive. Here, we employed deep sequencing of mRNA and small RNA species to gain insights into transcriptional differences among layers and their temporal dynamics during postnatal development of the mouse primary somatosensory neocortex. We identify a number of coding and noncoding transcripts with specific spatiotemporal expression and splicing patterns. We also identify signature trajectories and gene coexpression networks associated with distinct biological processes and transcriptional overlap between these processes. Finally, we provide data that allow the study of potential miRNA and mRNA interactions. Overall, this study provides an integrated view of the laminar and temporal expression dynamics of coding and noncoding transcripts in the mouse neocortex and a resource for studies of neurodevelopment and transcriptome.

  12. Spatial and temporal dynamics of the microbial community in the Hanford unconfined aquifer

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Xueju; McKinley, James P.; Resch, Charles T.; Kaluzny, Rachael M.; Lauber, C.; Fredrickson, Jim K.; Knight, Robbie C.; Konopka, Allan

    2012-03-29

    Pyrosequencing analysis of 16S rRNA genes was used to study temporal dynamics of groundwater Bacteria and Archaea over 10 months within 3 well clusters separated by ~30 m and located 250 m from the Columbia River on the Hanford Site, WA. Each cluster contained 3 wells screened at different depths ranging from 10 to 17 m that differed in hydraulic conductivities. Representative samples were selected for analyses of prokaryotic 16S and eukaryotic 18S rRNA gene copy numbers. Temporal changes in community composition occurred in all 9 wells over the 10 month sampling period. However, there were particularly strong effects near the top of the water table when the seasonal rise in the Columbia River caused river water intrusion at the top of the aquifer. The occurrence and disappearance of some microbial assemblages (such as Actinobacteria ACK-M1) were correlated to river water intrusion. This seasonal impact on microbial community structure was greater in the shallow saturated zone than deeper in the aquifer. Spatial and temporal patterns for several 16S rRNA gene operational taxonomic units associated with particular physiological functions (e.g.methane oxidizers and metal reducers) suggests dynamic changes in fluxes of electron donors and acceptors over an annual cycle. In addition, temporal dynamics in eukaryotic 18S rRNA gene copies and the dominance of protozoa in 18S clone libraries suggest that bacterial community dynamics could be affected not only by the physical and chemical environment, but also by top-down biological control.

  13. Spatio-temporal dynamics of security investments in an interdependent risk environment

    Science.gov (United States)

    Shafi, Kamran; Bender, Axel; Zhong, Weicai; Abbass, Hussein A.

    2012-10-01

    In a globalised world where risks spread through contagion, the decision of an entity to invest in securing its premises from stochastic risks no longer depends solely on its own actions but also on the actions of other interacting entities in the system. This phenomenon is commonly seen in many domains including airline, logistics and computer security and is referred to as Interdependent Security (IDS). An IDS game models this decision problem from a game-theoretic perspective and deals with the behavioural dynamics of risk-reduction investments in such settings. This paper enhances this model and investigates the spatio-temporal aspects of the IDS games. The spatio-temporal dynamics are studied using simple replicator dynamics on a variety of network structures and for various security cost tradeoffs that lead to different Nash equilibria in an IDS game. The simulation results show that the neighbourhood configuration has a greater effect on the IDS game dynamics than network structure. An in-depth empirical analysis of game dynamics is carried out on regular graphs, which leads to the articulation of necessary and sufficient conditions for dominance in IDS games under spatial constraints.

  14. Integrating Future Land Use Scenarios to Evaluate the Spatio-Temporal Dynamics of Landscape Ecological Security

    Directory of Open Access Journals (Sweden)

    Yi Lu

    2016-11-01

    Full Text Available Urban ecological security is the basic principle of national ecological security. However, analyses of the spatial and temporal dynamics of ecological security remain limited, especially those that consider different scenarios of urban development. In this study, an integrated method is proposed that combines the Conversion of Land Use and its Effects (CLUE-S model with the Pressure–State–Response (P-S-R framework to assess landscape ecological security (LES in Huangshan City, China under two scenarios. Our results suggest the following conclusions: (1 the spatial and temporal dynamics of ecological security are closely related to the urbanization process; (2 although the average values of landscape ecological security are similar under different scenarios, the areas of relatively high security levels vary considerably; and (3 spatial heterogeneity in ecological security exists between different districts and counties, and the city center and its vicinity may face relatively serious declines in ecological security in the future. Overall, the proposed method not only illustrates the spatio-temporal dynamics of landscape ecological security under different scenarios but also reveals the anthropogenic effects on ecosystems by differentiating between causes, effects, and human responses at the landscape scale. This information is of great significance to decision-makers for future urban planning and management.

  15. Integration of temporal and spatial properties of dynamic connectivity networks for automatic diagnosis of brain disease.

    Science.gov (United States)

    Jie, Biao; Liu, Mingxia; Shen, Dinggang

    2018-07-01

    Functional connectivity networks (FCNs) using resting-state functional magnetic resonance imaging (rs-fMRI) have been applied to the analysis and diagnosis of brain disease, such as Alzheimer's disease (AD) and its prodrome, i.e., mild cognitive impairment (MCI). Different from conventional studies focusing on static descriptions on functional connectivity (FC) between brain regions in rs-fMRI, recent studies have resorted to dynamic connectivity networks (DCNs) to characterize the dynamic changes of FC, since dynamic changes of FC may indicate changes in macroscopic neural activity patterns in cognitive and behavioral aspects. However, most of the existing studies only investigate the temporal properties of DCNs (e.g., temporal variability of FC between specific brain regions), ignoring the important spatial properties of the network (e.g., spatial variability of FC associated with a specific brain region). Also, emerging evidence on FCNs has suggested that, besides temporal variability, there is significant spatial variability of activity foci over time. Hence, integrating both temporal and spatial properties of DCNs can intuitively promote the performance of connectivity-network-based learning methods. In this paper, we first define a new measure to characterize the spatial variability of DCNs, and then propose a novel learning framework to integrate both temporal and spatial variabilities of DCNs for automatic brain disease diagnosis. Specifically, we first construct DCNs from the rs-fMRI time series at successive non-overlapping time windows. Then, we characterize the spatial variability of a specific brain region by computing the correlation of functional sequences (i.e., the changing profile of FC between a pair of brain regions within all time windows) associated with this region. Furthermore, we extract both temporal variabilities and spatial variabilities from DCNs as features, and integrate them for classification by using manifold regularized multi

  16. Dynamic PET image reconstruction integrating temporal regularization associated with respiratory motion correction for applications in oncology

    Science.gov (United States)

    Merlin, Thibaut; Visvikis, Dimitris; Fernandez, Philippe; Lamare, Frédéric

    2018-02-01

    Respiratory motion reduces both the qualitative and quantitative accuracy of PET images in oncology. This impact is more significant for quantitative applications based on kinetic modeling, where dynamic acquisitions are associated with limited statistics due to the necessity of enhanced temporal resolution. The aim of this study is to address these drawbacks, by combining a respiratory motion correction approach with temporal regularization in a unique reconstruction algorithm for dynamic PET imaging. Elastic transformation parameters for the motion correction are estimated from the non-attenuation-corrected PET images. The derived displacement matrices are subsequently used in a list-mode based OSEM reconstruction algorithm integrating a temporal regularization between the 3D dynamic PET frames, based on temporal basis functions. These functions are simultaneously estimated at each iteration, along with their relative coefficients for each image voxel. Quantitative evaluation has been performed using dynamic FDG PET/CT acquisitions of lung cancer patients acquired on a GE DRX system. The performance of the proposed method is compared with that of a standard multi-frame OSEM reconstruction algorithm. The proposed method achieved substantial improvements in terms of noise reduction while accounting for loss of contrast due to respiratory motion. Results on simulated data showed that the proposed 4D algorithms led to bias reduction values up to 40% in both tumor and blood regions for similar standard deviation levels, in comparison with a standard 3D reconstruction. Patlak parameter estimations on reconstructed images with the proposed reconstruction methods resulted in 30% and 40% bias reduction in the tumor and lung region respectively for the Patlak slope, and a 30% bias reduction for the intercept in the tumor region (a similar Patlak intercept was achieved in the lung area). Incorporation of the respiratory motion correction using an elastic model along with a

  17. The Temporal Derivative of Expected Utility: A Neural Mechanism for Dynamic Decision-making

    Science.gov (United States)

    Zhang, Xian; Hirsch, Joy

    2012-01-01

    Real world tasks involving moving targets, such as driving a vehicle, are performed based on continuous decisions thought to depend upon the temporal derivative of the expected utility (∂V/∂t), where the expected utility (V) is the effective value of a future reward. However, those neural mechanisms that underlie dynamic decision-making are not well understood. This study investigates human neural correlates of both V and ∂V/∂t using fMRI and a novel experimental paradigm based on a pursuit-evasion game optimized to isolate components of dynamic decision processes. Our behavioral data show that players of the pursuit-evasion game adopt an exponential discounting function, supporting the expected utility theory. The continuous functions of V and ∂V/∂t were derived from the behavioral data and applied as regressors in fMRI analysis, enabling temporal resolution that exceeded the sampling rate of image acquisition, hyper-temporal resolution, by taking advantage of numerous trials that provide rich and independent manipulation of those variables. V and ∂V/∂t were each associated with distinct neural activity. Specifically, ∂V/∂t was associated with anterior and posterior cingulate cortices, superior parietal lobule, and ventral pallidum, whereas V was primarily associated with supplementary motor, pre and post central gyri, cerebellum, and thalamus. The association between the ∂V/∂t and brain regions previously related to decision-making is consistent with the primary role of the temporal derivative of expected utility in dynamic decision-making. PMID:22963852

  18. The temporal derivative of expected utility: a neural mechanism for dynamic decision-making.

    Science.gov (United States)

    Zhang, Xian; Hirsch, Joy

    2013-01-15

    Real world tasks involving moving targets, such as driving a vehicle, are performed based on continuous decisions thought to depend upon the temporal derivative of the expected utility (∂V/∂t), where the expected utility (V) is the effective value of a future reward. However, the neural mechanisms that underlie dynamic decision-making are not well understood. This study investigates human neural correlates of both V and ∂V/∂t using fMRI and a novel experimental paradigm based on a pursuit-evasion game optimized to isolate components of dynamic decision processes. Our behavioral data show that players of the pursuit-evasion game adopt an exponential discounting function, supporting the expected utility theory. The continuous functions of V and ∂V/∂t were derived from the behavioral data and applied as regressors in fMRI analysis, enabling temporal resolution that exceeded the sampling rate of image acquisition, hyper-temporal resolution, by taking advantage of numerous trials that provide rich and independent manipulation of those variables. V and ∂V/∂t were each associated with distinct neural activity. Specifically, ∂V/∂t was associated with anterior and posterior cingulate cortices, superior parietal lobule, and ventral pallidum, whereas V was primarily associated with supplementary motor, pre and post central gyri, cerebellum, and thalamus. The association between the ∂V/∂t and brain regions previously related to decision-making is consistent with the primary role of the temporal derivative of expected utility in dynamic decision-making. Copyright © 2012 Elsevier Inc. All rights reserved.

  19. Spatial and Temporal Dynamics and Value of Nature-Based Recreation, Estimated via Social Media

    Science.gov (United States)

    Watson, Keri B.; Wood, Spencer A.; Ricketts, Taylor H.

    2016-01-01

    Conserved lands provide multiple ecosystem services, including opportunities for nature-based recreation. Managing this service requires understanding the landscape attributes underpinning its provision, and how changes in land management affect its contribution to human wellbeing over time. However, evidence from both spatially explicit and temporally dynamic analyses is scarce, often due to data limitations. In this study, we investigated nature-based recreation within conserved lands in Vermont, USA. We used geotagged photographs uploaded to the photo-sharing website Flickr to quantify visits by in-state and out-of-state visitors, and we multiplied visits by mean trip expenditures to show that conserved lands contributed US $1.8 billion (US $0.18–20.2 at 95% confidence) to Vermont’s tourism industry between 2007 and 2014. We found eight landscape attributes explained the pattern of visits to conserved lands; visits were higher in larger conserved lands, with less forest cover, greater trail density and more opportunities for snow sports. Some of these attributes differed from those found in other locations, but all aligned with our understanding of recreation in Vermont. We also found that using temporally static models to inform conservation decisions may have perverse outcomes for nature-based recreation. For example, static models suggest conserved land with less forest cover receive more visits, but temporally dynamic models suggest clearing forests decreases, rather than increases, visits to these sites. Our results illustrate the importance of understanding both the spatial and temporal dynamics of ecosystem services for conservation decision-making. PMID:27611325

  20. Dynamic spatial organization of the occipito-temporal word form area for second language processing.

    Science.gov (United States)

    Gao, Yue; Sun, Yafeng; Lu, Chunming; Ding, Guosheng; Guo, Taomei; Malins, Jeffrey G; Booth, James R; Peng, Danling; Liu, Li

    2017-08-01

    Despite the left occipito-temporal region having shown consistent activation in visual word form processing across numerous studies in different languages, the mechanisms by which word forms of second languages are processed in this region remain unclear. To examine this more closely, 16 Chinese-English and 14 English-Chinese late bilinguals were recruited to perform lexical decision tasks to visually presented words in both their native and second languages (L1 and L2) during functional magnetic resonance imaging scanning. Here we demonstrate that visual word form processing for L1 versus L2 engaged different spatial areas of the left occipito-temporal region. Namely, the spatial organization of the visual word form processing in the left occipito-temporal region is more medial and posterior for L2 than L1 processing in Chinese-English bilinguals, whereas activation is more lateral and anterior for L2 in English-Chinese bilinguals. In addition, for Chinese-English bilinguals, more lateral recruitment of the occipito-temporal region was correlated with higher L2 proficiency, suggesting higher L2 proficiency is associated with greater involvement of L1-preferred mechanisms. For English-Chinese bilinguals, higher L2 proficiency was correlated with more lateral and anterior activation of the occipito-temporal region, suggesting higher L2 proficiency is associated with greater involvement of L2-preferred mechanisms. Taken together, our results indicate that L1 and L2 recruit spatially different areas of the occipito-temporal region in visual word processing when the two scripts belong to different writing systems, and that the spatial organization of this region for L2 visual word processing is dynamically modulated by L2 proficiency. Specifically, proficiency in L2 in Chinese-English is associated with assimilation to the native language mechanisms, whereas L2 in English-Chinese is associated with accommodation to second language mechanisms. Copyright © 2017

  1. Bursts and heavy tails in temporal and sequential dynamics of foraging decisions.

    Directory of Open Access Journals (Sweden)

    Kanghoon Jung

    2014-08-01

    Full Text Available A fundamental understanding of behavior requires predicting when and what an individual will choose. However, the actual temporal and sequential dynamics of successive choices made among multiple alternatives remain unclear. In the current study, we tested the hypothesis that there is a general bursting property in both the timing and sequential patterns of foraging decisions. We conducted a foraging experiment in which rats chose among four different foods over a continuous two-week time period. Regarding when choices were made, we found bursts of rapidly occurring actions, separated by time-varying inactive periods, partially based on a circadian rhythm. Regarding what was chosen, we found sequential dynamics in affective choices characterized by two key features: (a a highly biased choice distribution; and (b preferential attachment, in which the animals were more likely to choose what they had previously chosen. To capture the temporal dynamics, we propose a dual-state model consisting of active and inactive states. We also introduce a satiation-attainment process for bursty activity, and a non-homogeneous Poisson process for longer inactivity between bursts. For the sequential dynamics, we propose a dual-control model consisting of goal-directed and habit systems, based on outcome valuation and choice history, respectively. This study provides insights into how the bursty nature of behavior emerges from the interaction of different underlying systems, leading to heavy tails in the distribution of behavior over time and choices.

  2. Spatio-temporal correlations in models of collective motion ruled by different dynamical laws.

    Science.gov (United States)

    Cavagna, Andrea; Conti, Daniele; Giardina, Irene; Grigera, Tomas S; Melillo, Stefania; Viale, Massimiliano

    2016-11-15

    Information transfer is an essential factor in determining the robustness of biological systems with distributed control. The most direct way to study the mechanisms ruling information transfer is to experimentally observe the propagation across the system of a signal triggered by some perturbation. However, this method may be inefficient for experiments in the field, as the possibilities to perturb the system are limited and empirical observations must rely on natural events. An alternative approach is to use spatio-temporal correlations to probe the information transfer mechanism directly from the spontaneous fluctuations of the system, without the need to have an actual propagating signal on record. Here we test this method on models of collective behaviour in their deeply ordered phase by using ground truth data provided by numerical simulations in three dimensions. We compare two models characterized by very different dynamical equations and information transfer mechanisms: the classic Vicsek model, describing an overdamped noninertial dynamics and the inertial spin model, characterized by an underdamped inertial dynamics. By using dynamic finite-size scaling, we show that spatio-temporal correlations are able to distinguish unambiguously the diffusive information transfer mechanism of the Vicsek model from the linear mechanism of the inertial spin model.

  3. Bursts and Heavy Tails in Temporal and Sequential Dynamics of Foraging Decisions

    Science.gov (United States)

    Jung, Kanghoon; Jang, Hyeran; Kralik, Jerald D.; Jeong, Jaeseung

    2014-01-01

    A fundamental understanding of behavior requires predicting when and what an individual will choose. However, the actual temporal and sequential dynamics of successive choices made among multiple alternatives remain unclear. In the current study, we tested the hypothesis that there is a general bursting property in both the timing and sequential patterns of foraging decisions. We conducted a foraging experiment in which rats chose among four different foods over a continuous two-week time period. Regarding when choices were made, we found bursts of rapidly occurring actions, separated by time-varying inactive periods, partially based on a circadian rhythm. Regarding what was chosen, we found sequential dynamics in affective choices characterized by two key features: (a) a highly biased choice distribution; and (b) preferential attachment, in which the animals were more likely to choose what they had previously chosen. To capture the temporal dynamics, we propose a dual-state model consisting of active and inactive states. We also introduce a satiation-attainment process for bursty activity, and a non-homogeneous Poisson process for longer inactivity between bursts. For the sequential dynamics, we propose a dual-control model consisting of goal-directed and habit systems, based on outcome valuation and choice history, respectively. This study provides insights into how the bursty nature of behavior emerges from the interaction of different underlying systems, leading to heavy tails in the distribution of behavior over time and choices. PMID:25122498

  4. INFORMATION MINING OF SPATIO-TEMPORAL EVOLUTION OF LAKES BASED ON MULTIPLE DYNAMIC MEASUREMENTS

    Directory of Open Access Journals (Sweden)

    W. Feng

    2017-09-01

    Full Text Available Lakes are important water resources and integral parts of the natural ecosystem, and it is of great significance to study the evolution of lakes. The area of each lake increased and decreased at the same time in natural condition, only but the net change of lakes’ area is the result of the bidirectional evolution of lakes. In this paper, considering the effects of net fragmentation, net attenuation, swap change and spatial invariant part in lake evolution, a comprehensive evaluation indexes of lake dynamic evolution were defined,. Such degree contains three levels of measurement: 1 the swap dynamic degree (SDD reflects the space activity of lakes in the study period. 2 the attenuation dynamic degree (ADD reflects the net attenuation of lakes into non-lake areas. 3 the fragmentation dynamic degree (FDD reflects the trend of lakes to be divided and broken into smaller lakes. Three levels of dynamic measurement constitute the three-dimensional "Swap - attenuation – fragmentation" dynamic evolution measurement system of lakes. To show its effectiveness, the dynamic measurement was applied to lakes in Jianghan Plain, the middle Yangtze region of China for a more detailed analysis of lakes from 1984 to 2014. In combination with spatial-temporal location characteristics of lakes, the hidden information in lake evolution in the past 30 years can be revealed.

  5. A general science-based framework for dynamical spatio-temporal models

    Science.gov (United States)

    Wikle, C.K.; Hooten, M.B.

    2010-01-01

    Spatio-temporal statistical models are increasingly being used across a wide variety of scientific disciplines to describe and predict spatially-explicit processes that evolve over time. Correspondingly, in recent years there has been a significant amount of research on new statistical methodology for such models. Although descriptive models that approach the problem from the second-order (covariance) perspective are important, and innovative work is being done in this regard, many real-world processes are dynamic, and it can be more efficient in some cases to characterize the associated spatio-temporal dependence by the use of dynamical models. The chief challenge with the specification of such dynamical models has been related to the curse of dimensionality. Even in fairly simple linear, first-order Markovian, Gaussian error settings, statistical models are often over parameterized. Hierarchical models have proven invaluable in their ability to deal to some extent with this issue by allowing dependency among groups of parameters. In addition, this framework has allowed for the specification of science based parameterizations (and associated prior distributions) in which classes of deterministic dynamical models (e. g., partial differential equations (PDEs), integro-difference equations (IDEs), matrix models, and agent-based models) are used to guide specific parameterizations. Most of the focus for the application of such models in statistics has been in the linear case. The problems mentioned above with linear dynamic models are compounded in the case of nonlinear models. In this sense, the need for coherent and sensible model parameterizations is not only helpful, it is essential. Here, we present an overview of a framework for incorporating scientific information to motivate dynamical spatio-temporal models. First, we illustrate the methodology with the linear case. We then develop a general nonlinear spatio-temporal framework that we call general quadratic

  6. Temporal dynamics and transcriptional control using single-cell gene expression analysis.

    Science.gov (United States)

    Kouno, Tsukasa; de Hoon, Michiel; Mar, Jessica C; Tomaru, Yasuhiro; Kawano, Mitsuoki; Carninci, Piero; Suzuki, Harukazu; Hayashizaki, Yoshihide; Shin, Jay W

    2013-01-01

    Changes in environmental conditions lead to expression variation that manifest at the level of gene regulatory networks. Despite a strong understanding of the role noise plays in synthetic biological systems, it remains unclear how propagation of expression heterogeneity in an endogenous regulatory network is distributed and utilized by cells transitioning through a key developmental event. Here we investigate the temporal dynamics of a single-cell transcriptional network of 45 transcription factors in THP-1 human myeloid monocytic leukemia cells undergoing differentiation to macrophages. We systematically measure temporal regulation of expression and variation by profiling 120 single cells at eight distinct time points, and infer highly controlled regulatory modules through which signaling operates with stochastic effects. This reveals dynamic and specific rewiring as a cellular strategy for differentiation. The integration of both positive and negative co-expression networks further identifies the proto-oncogene MYB as a network hinge to modulate both the pro- and anti-differentiation pathways. Compared to averaged cell populations, temporal single-cell expression profiling provides a much more powerful technique to probe for mechanistic insights underlying cellular differentiation. We believe that our approach will form the basis of novel strategies to study the regulation of transcription at a single-cell level.

  7. Temporal variability in phosphorus transfers: classifying concentration–discharge event dynamics

    Directory of Open Access Journals (Sweden)

    P. Haygarth

    2004-01-01

    Full Text Available The importance of temporal variability in relationships between phosphorus (P concentration (Cp and discharge (Q is linked to a simple means of classifying the circumstances of Cp–Q relationships in terms of functional types of response. New experimental data at the upstream interface of grassland soil and catchment systems at a range of scales (lysimeters to headwaters in England and Australia are used to demonstrate the potential of such an approach. Three types of event are defined as Types 1–3, depending on whether the relative change in Q exceeds the relative change in Cp (Type 1, whether Cp and Q are positively inter-related (Type 2 and whether Cp varies yet Q is unchanged (Type 3. The classification helps to characterise circumstances that can be explained mechanistically in relation to (i the scale of the study (with a tendency towards Type 1 in small scale lysimeters, (ii the form of P with a tendency for Type 1 for soluble (i.e., p–Q relationships that can be developed further to contribute to future models of P transfer and delivery from slope to stream. Studies that evaluate the temporal dynamics of the transfer of P are currently grossly under-represented in comparison with models based on static/spatial factors. Keywords: phosphorus, concentration, discharge, lysimeters, temporal dynamics, overland flow

  8. Dynamic evolving spiking neural networks for on-line spatio- and spectro-temporal pattern recognition.

    Science.gov (United States)

    Kasabov, Nikola; Dhoble, Kshitij; Nuntalid, Nuttapod; Indiveri, Giacomo

    2013-05-01

    On-line learning and recognition of spatio- and spectro-temporal data (SSTD) is a very challenging task and an important one for the future development of autonomous machine learning systems with broad applications. Models based on spiking neural networks (SNN) have already proved their potential in capturing spatial and temporal data. One class of them, the evolving SNN (eSNN), uses a one-pass rank-order learning mechanism and a strategy to evolve a new spiking neuron and new connections to learn new patterns from incoming data. So far these networks have been mainly used for fast image and speech frame-based recognition. Alternative spike-time learning methods, such as Spike-Timing Dependent Plasticity (STDP) and its variant Spike Driven Synaptic Plasticity (SDSP), can also be used to learn spatio-temporal representations, but they usually require many iterations in an unsupervised or semi-supervised mode of learning. This paper introduces a new class of eSNN, dynamic eSNN, that utilise both rank-order learning and dynamic synapses to learn SSTD in a fast, on-line mode. The paper also introduces a new model called deSNN, that utilises rank-order learning and SDSP spike-time learning in unsupervised, supervised, or semi-supervised modes. The SDSP learning is used to evolve dynamically the network changing connection weights that capture spatio-temporal spike data clusters both during training and during recall. The new deSNN model is first illustrated on simple examples and then applied on two case study applications: (1) moving object recognition using address-event representation (AER) with data collected using a silicon retina device; (2) EEG SSTD recognition for brain-computer interfaces. The deSNN models resulted in a superior performance in terms of accuracy and speed when compared with other SNN models that use either rank-order or STDP learning. The reason is that the deSNN makes use of both the information contained in the order of the first input spikes

  9. Towards understanding temporal and spatial dynamics of seagrass landscapes using time-series remote sensing

    Science.gov (United States)

    Lyons, Mitchell B.; Roelfsema, Chris M.; Phinn, Stuart R.

    2013-03-01

    The spatial and temporal dynamics of seagrasses have been well studied at the leaf to patch scales, however, the link to large spatial extent landscape and population dynamics is still unresolved in seagrass ecology. Traditional remote sensing approaches have lacked the temporal resolution and consistency to appropriately address this issue. This study uses two high temporal resolution time-series of thematic seagrass cover maps to examine the spatial and temporal dynamics of seagrass at both an inter- and intra-annual time scales, one of the first globally to do so at this scale. Previous work by the authors developed an object-based approach to map seagrass cover level distribution from a long term archive of Landsat TM and ETM+ images on the Eastern Banks (≈200 km2), Moreton Bay, Australia. In this work a range of trend and time-series analysis methods are demonstrated for a time-series of 23 annual maps from 1988 to 2010 and a time-series of 16 monthly maps during 2008-2010. Significant new insight was presented regarding the inter- and intra-annual dynamics of seagrass persistence over time, seagrass cover level variability, seagrass cover level trajectory, and change in area of seagrass and cover levels over time. Overall we found that there was no significant decline in total seagrass area on the Eastern Banks, but there was a significant decline in seagrass cover level condition. A case study of two smaller communities within the Eastern Banks that experienced a decline in both overall seagrass area and condition are examined in detail, highlighting possible differences in environmental and process drivers. We demonstrate how trend and time-series analysis enabled seagrass distribution to be appropriately assessed in context of its spatial and temporal history and provides the ability to not only quantify change, but also describe the type of change. We also demonstrate the potential use of time-series analysis products to investigate seagrass growth and

  10. Insights into soil carbon dynamics across climatic and geologic gradients from temporally-resolved radiocarbon measurements

    Science.gov (United States)

    van der Voort, T. S.; Hagedorn, F.; Mannu, U.; Walthert, L.; McIntyre, C.; Eglinton, T. I.

    2016-12-01

    Soil carbon constitutes the largest terrestrial reservoir of organic carbon, and therefore quantifying soil organic matter dynamics (carbon turnover, stocks and fluxes) across spatial gradients is essential for an understanding of the carbon cycle and the impacts of global change. In particular, links between soil carbon dynamics and different climatic and compositional factors remains poorly understood. Radiocarbon constitutes a powerful tool for unraveling soil carbon dynamics. Temporally-resolved radiocarbon measurements, which take advantage of "bomb-radiocarbon"-driven changes in atmospheric 14C, enable further constraints to be placed on C turnover times. These in turn can yield more precise flux estimates for both upper and deeper soil horizons. This project combines bulk radiocarbon measurements on a suite of soil profiles spanning strong climatic (MAT 1.3-9.2°C, MAP 600 to 2100 mm m-2y-1) and geologic gradients with a more in-depth approach for a subset of locations. For this subset, temporal and carbon-fraction specific radiocarbon data has been acquired for both topsoil and deeper soils. These well-studied sites are part of the Long-Term Forest Ecosystem Research (LWF) program of the Swiss Federal Institute for Forest, Snow and Landscape research (WSL). Resulting temporally-resolved turnover estimates are coupled to carbon stocks, fluxes across this wide range of forest ecosystems and are examined in the context of environmental drivers (temperature, precipitation, primary production and soil moisture) as well as composition (sand, silt and clay content). Statistical analysis on the region-scale - correlating radiocarbon signature with climatic variables such as temperature, precipitation, primary production and elevation - indicates that composition rather than climate is a key driver of ­­Δ14C signatures. Estimates of carbon turnover, stocks and fluxes derived from temporally-resolved measurements highlight the pivotal role of soil moisture as a

  11. The Temporal Dynamics of Visual Search: Evidence for Parallel Processing in Feature and Conjunction Searches

    Science.gov (United States)

    McElree, Brian; Carrasco, Marisa

    2012-01-01

    Feature and conjunction searches have been argued to delineate parallel and serial operations in visual processing. The authors evaluated this claim by examining the temporal dynamics of the detection of features and conjunctions. The 1st experiment used a reaction time (RT) task to replicate standard mean RT patterns and to examine the shapes of the RT distributions. The 2nd experiment used the response-signal speed–accuracy trade-off (SAT) procedure to measure discrimination (asymptotic detection accuracy) and detection speed (processing dynamics). Set size affected discrimination in both feature and conjunction searches but affected detection speed only in the latter. Fits of models to the SAT data that included a serial component overpredicted the magnitude of the observed dynamics differences. The authors concluded that both features and conjunctions are detected in parallel. Implications for the role of attention in visual processing are discussed. PMID:10641310

  12. Investigating fine-scale spatio-temporal predator-prey patterns in dynamic marine ecosystems: a functional data analysis approach

    NARCIS (Netherlands)

    Embling, C.B.; Illian, J.; Armstrong, E.; van der Kooij, J.; Sharples, J.; Camphuysen, K.C.J.; Scott, B.E.

    2012-01-01

    1. Spatial management of marine ecosystems requires detailed knowledge of spatio-temporal mechanisms linking physical and biological processes. Tidal currents, the main driver of ecosystem dynamics in temperate coastal ecosystems, influence predator foraging ecology by affecting prey distribution

  13. Spatial and temporal dynamics of multidimensional well-being, livelihoods and ecosystem services in coastal Bangladesh

    Science.gov (United States)

    Adams, Helen; Adger, W. Neil; Ahmad, Sate; Ahmed, Ali; Begum, Dilruba; Lázár, Attila N.; Matthews, Zoe; Rahman, Mohammed Mofizur; Streatfield, Peter Kim

    2016-01-01

    Populations in resource dependent economies gain well-being from the natural environment, in highly spatially and temporally variable patterns. To collect information on this, we designed and implemented a 1586-household quantitative survey in the southwest coastal zone of Bangladesh. Data were collected on material, subjective and health dimensions of well-being in the context of natural resource use, particularly agriculture, aquaculture, mangroves and fisheries. The questionnaire included questions on factors that mediate poverty outcomes: mobility and remittances; loans and micro-credit; environmental perceptions; shocks; and women’s empowerment. The data are stratified by social-ecological system to take into account spatial dynamics and the survey was repeated with the same respondents three times within a year to incorporate seasonal dynamics. The dataset includes blood pressure measurements and height and weight of men, women and children. In addition, the household listing includes basic data on livelihoods and income for approximately 10,000 households. The dataset facilitates interdisciplinary research on spatial and temporal dynamics of well-being in the context of natural resource dependence in low income countries. PMID:27824340

  14. A comprehensive model of audiovisual perception: both percept and temporal dynamics.

    Directory of Open Access Journals (Sweden)

    Patricia Besson

    Full Text Available The sparse information captured by the sensory systems is used by the brain to apprehend the environment, for example, to spatially locate the source of audiovisual stimuli. This is an ill-posed inverse problem whose inherent uncertainty can be solved by jointly processing the information, as well as introducing constraints during this process, on the way this multisensory information is handled. This process and its result--the percept--depend on the contextual conditions perception takes place in. To date, perception has been investigated and modeled on the basis of either one of two of its dimensions: the percept or the temporal dynamics of the process. Here, we extend our previously proposed audiovisual perception model to predict both these dimensions to capture the phenomenon as a whole. Starting from a behavioral analysis, we use a data-driven approach to elicit a bayesian network which infers the different percepts and dynamics of the process. Context-specific independence analyses enable us to use the model's structure to directly explore how different contexts affect the way subjects handle the same available information. Hence, we establish that, while the percepts yielded by a unisensory stimulus or by the non-fusion of multisensory stimuli may be similar, they result from different processes, as shown by their differing temporal dynamics. Moreover, our model predicts the impact of bottom-up (stimulus driven factors as well as of top-down factors (induced by instruction manipulation on both the perception process and the percept itself.

  15. Femtosecond laser spectroscopy of spins: Magnetization dynamics in thin magnetic films with spatio-temporal resolution

    International Nuclear Information System (INIS)

    Carpene, E.; Mancini, E.; Dallera, C.; Puppin, E.; De Silvestri, S.

    2010-01-01

    Based on the Magneto-Optical Kerr Effect (MOKE), we have developed an experimental set-up that allows us to fully characterize the magnetization dynamics in thin magnetic films by measuring all three real space components of the magnetization vector M. By means of the pump-probe technique it is possible to extract the time dependence of each individual projection with sub-picosecond resolution. This method has been exploited to investigate the temporal evolution of the magnetization (modulus and orientation) induced by an ultrashort laser pulse in thin epitaxial iron films. According to our results, we deduced that the initial, sub-picosecond demagnetization is established at the electronic level through electron-magnon excitations. The subsequent dynamics is characterized by a precessional motion on the 100 ps time scale, around an effective, time-dependent magnetic field. Following the full dynamics of M, the temporal evolution of the magneto-crystalline anisotropy constant can be unambiguously determined, providing the experimental evidence that the precession is triggered by the rapid, optically-induced misalignment between the magnetization vector and the effective magnetic field. These results suggest a possible pathway toward the ultrarapid switching of the magnetization.

  16. Method to investigate temporal dynamics of ganglion and other retinal cells in the living human eye

    Science.gov (United States)

    Kurokawa, Kazuhiro; Liu, Zhuolin; Crowell, James; Zhang, Furu; Miller, Donald T.

    2018-02-01

    The inner retina is critical for visual processing, but much remains unknown about its neural circuitry and vulnerability to disease. A major bottleneck has been our inability to observe the structure and function of the cells composing these retinal layers in the living human eye. Here, we present a noninvasive method to observe both structural and functional information. Adaptive optics optical coherence tomography (AO-OCT) is used to resolve the inner retinal cells in all three dimensions and novel post processing algorithms are applied to extract structure and physiology down to the cellular level. AO-OCT captured the 3D mosaic of individual ganglion cell somas, retinal nerve fiber bundles of micron caliber, and microglial cells, all in exquisite detail. Time correlation analysis of the AO-OCT videos revealed notable temporal differences between the principal layers of the inner retina. The GC layer was more dynamic than the nerve fiber and inner plexiform layers. At the cellular level, we applied a customized correlation method to individual GCL somas, and found a mean time constant of activity of 0.57 s and spread of +/-0.1 s suggesting a range of physiological dynamics even in the same cell type. Extending our method to slower dynamics (from minutes to one year), time-lapse imaging and temporal speckle contrast revealed appendage and soma motion of resting microglial cells at the retinal surface.

  17. Dynamics of temporally localized states in passively mode-locked semiconductor lasers

    Science.gov (United States)

    Schelte, C.; Javaloyes, J.; Gurevich, S. V.

    2018-05-01

    We study the emergence and the stability of temporally localized structures in the output of a semiconductor laser passively mode locked by a saturable absorber in the long-cavity regime. For large yet realistic values of the linewidth enhancement factor, we disclose the existence of secondary dynamical instabilities where the pulses develop regular and subsequent irregular temporal oscillations. By a detailed bifurcation analysis we show that additional solution branches that consist of multipulse (molecules) solutions exist. We demonstrate that the various solution curves for the single and multipeak pulses can splice and intersect each other via transcritical bifurcations, leading to a complex web of solutions. Our analysis is based on a generic model of mode locking that consists of a time-delayed dynamical system, but also on a much more numerically efficient, yet approximate, partial differential equation. We compare the results of the bifurcation analysis of both models in order to assess up to which point the two approaches are equivalent. We conclude our analysis by the study of the influence of group velocity dispersion, which is only possible in the framework of the partial differential equation model, and we show that it may have a profound impact on the dynamics of the localized states.

  18. Embodiment of intersubjective time: relational dynamics as attractors in the temporal coordination of interpersonal behaviors and experiences.

    Science.gov (United States)

    Laroche, Julien; Berardi, Anna Maria; Brangier, Eric

    2014-01-01

    This paper addresses the issue of "being together," and more specifically the issue of "being together in time." We provide with an integrative framework that is inspired by phenomenology, the enactive approach and dynamical systems theories. To do so, we first define embodiment as a living and lived phenomenon that emerges from agent-world coupling. We then show that embodiment is essentially dynamical and therefore we describe experiential, behavioral and brain dynamics. Both lived temporality and the temporality of the living appear to be complex, multiscale phenomena. Next we discuss embodied dynamics in the context of interpersonal interactions, and briefly review the empirical literature on between-persons temporal coordination. Overall, we propose that being together in time emerges from the relational dynamics of embodied interactions and their flexible co-regulation.

  19. Impact of Partial Time Delay on Temporal Dynamics of Watts-Strogatz Small-World Neuronal Networks

    Science.gov (United States)

    Yan, Hao; Sun, Xiaojuan

    2017-06-01

    In this paper, we mainly discuss effects of partial time delay on temporal dynamics of Watts-Strogatz (WS) small-world neuronal networks by controlling two parameters. One is the time delay τ and the other is the probability of partial time delay pdelay. Temporal dynamics of WS small-world neuronal networks are discussed with the aid of temporal coherence and mean firing rate. With the obtained simulation results, it is revealed that for small time delay τ, the probability pdelay could weaken temporal coherence and increase mean firing rate of neuronal networks, which indicates that it could improve neuronal firings of the neuronal networks while destroying firing regularity. For large time delay τ, temporal coherence and mean firing rate do not have great changes with respect to pdelay. Time delay τ always has great influence on both temporal coherence and mean firing rate no matter what is the value of pdelay. Moreover, with the analysis of spike trains and histograms of interspike intervals of neurons inside neuronal networks, it is found that the effects of partial time delays on temporal coherence and mean firing rate could be the result of locking between the period of neuronal firing activities and the value of time delay τ. In brief, partial time delay could have great influence on temporal dynamics of the neuronal networks.

  20. Envelope detection using temporal magnetization dynamics of resonantly interacting spin-torque oscillator

    Science.gov (United States)

    Nakamura, Y.; Nishikawa, M.; Osawa, H.; Okamoto, Y.; Kanao, T.; Sato, R.

    2018-05-01

    In this article, we propose the detection method of the recorded data pattern by the envelope of the temporal magnetization dynamics of resonantly interacting spin-torque oscillator on the microwave assisted magnetic recording for three-dimensional magnetic recording. We simulate the envelope of the waveform from recorded dots with the staggered magnetization configuration, which are calculated by using a micromagnetic simulation. We study the data detection methods for the envelope and propose a soft-output Viterbi algorithm (SOVA) for partial response (PR) system as a signal processing system for three dimensional magnetic recording.

  1. The absence or temporal offset of visual feedback does not influence adaptation to novel movement dynamics.

    Science.gov (United States)

    McKenna, Erin; Bray, Laurence C Jayet; Zhou, Weiwei; Joiner, Wilsaan M

    2017-10-01

    Delays in transmitting and processing sensory information require correctly associating delayed feedback to issued motor commands for accurate error compensation. The flexibility of this alignment between motor signals and feedback has been demonstrated for movement recalibration to visual manipulations, but the alignment dependence for adapting movement dynamics is largely unknown. Here we examined the effect of visual feedback manipulations on force-field adaptation. Three subject groups used a manipulandum while experiencing a lag in the corresponding cursor motion (0, 75, or 150 ms). When the offset was applied at the start of the session (continuous condition), adaptation was not significantly different between groups. However, these similarities may be due to acclimation to the offset before motor adaptation. We tested additional subjects who experienced the same delays concurrent with the introduction of the perturbation (abrupt condition). In this case adaptation was statistically indistinguishable from the continuous condition, indicating that acclimation to feedback delay was not a factor. In addition, end-point errors were not significantly different across the delay or onset conditions, but end-point correction (e.g., deceleration duration) was influenced by the temporal offset. As an additional control, we tested a group of subjects who performed without visual feedback and found comparable movement adaptation results. These results suggest that visual feedback manipulation (absence or temporal misalignment) does not affect adaptation to novel dynamics, independent of both acclimation and perceptual awareness. These findings could have implications for modeling how the motor system adjusts to errors despite concurrent delays in sensory feedback information. NEW & NOTEWORTHY A temporal offset between movement and distorted visual feedback (e.g., visuomotor rotation) influences the subsequent motor recalibration, but the effects of this offset for

  2. From Brain-Environment Connections to Temporal Dynamics and Social Interaction: Principles of Human Brain Function.

    Science.gov (United States)

    Hari, Riitta

    2017-06-07

    Experimental data about brain function accumulate faster than does our understanding of how the brain works. To tackle some general principles at the grain level of behavior, I start from the omnipresent brain-environment connection that forces regularities of the physical world to shape the brain. Based on top-down processing, added by sparse sensory information, people are able to form individual "caricature worlds," which are similar enough to be shared among other people and which allow quick and purposeful reactions to abrupt changes. Temporal dynamics and social interaction in natural environments serve as further essential organizing principles of human brain function. Copyright © 2017 Elsevier Inc. All rights reserved.

  3. Temperamental traits and results of psychoaptitude tests in applicants to become a cadet officer in the Italian Navy.

    Science.gov (United States)

    Maremmani, Icro; Maremmani, Angelo Giovanni Icro; Leonardi, Annalisa; Rovai, Luca; Bacciardi, Silvia; Rugani, Fabio; Dell'Osso, Liliana; Akiskal, Kareen; Akiskal, S Hagop

    2013-09-05

    Consistently with the involvement of affective temperaments in professional choices, our research team is aiming to outline the temperamental profile of subjects who are applying to enter a military career in the Italian Armed Forces. In this study we aim to verify the importance of temperamental traits not only in choosing the military career as a profession, but also in passing or failing the entrance examinations. We compared the affective temperaments (evaluated by TEMPS-A[P]) of those applying to become a cadet officer in the Italian Navy, divided into various subgroups depending on whether they passed or failed the entrance examination at various levels (high school final test, medical (physical and psychiatric), mathematical examination and aptitude test). We also tested for correlations between grades received and temperamental scores. Higher scores for those with a hyperthymic and lower scores for those with a depressive, cyclothymic or irritable temperament characterized applicants taking medical exams and aptitude tests. Higher scores on the high school final test correlated with lower hyperthymic, cyclothymic and irritable temperament scores. No correlations were found between temperamental traits and mathematical examinations. Multivariate analysis stressed the negative impact of a cyclothymic temperament and the poor discriminant power of temperaments regarding medical and mathematical examinations, and aptitude tests. Conversely, temperaments showed good discriminant power as far as psychiatric examinations are concerned. Hyperthymic temperamental traits appear to be important not only in choosing a profession, but also in passing entrance examinations. Even so, affective temperaments (strong hyperthymic and weak cyclothymic, depressive and irritable traits) are the only successfully predictors of the outcome of psychiatric examinations and, to a lesser extent, medical examinations and aptitude tests. Achieving high school graduation and passing

  4. Temporal dynamics of hot desert microbial communities reveal structural and functional responses to water input.

    Science.gov (United States)

    Armstrong, Alacia; Valverde, Angel; Ramond, Jean-Baptiste; Makhalanyane, Thulani P; Jansson, Janet K; Hopkins, David W; Aspray, Thomas J; Seely, Mary; Trindade, Marla I; Cowan, Don A

    2016-09-29

    The temporal dynamics of desert soil microbial communities are poorly understood. Given the implications for ecosystem functioning under a global change scenario, a better understanding of desert microbial community stability is crucial. Here, we sampled soils in the central Namib Desert on sixteen different occasions over a one-year period. Using Illumina-based amplicon sequencing of the 16S rRNA gene, we found that α-diversity (richness) was more variable at a given sampling date (spatial variability) than over the course of one year (temporal variability). Community composition remained essentially unchanged across the first 10 months, indicating that spatial sampling might be more important than temporal sampling when assessing β-diversity patterns in desert soils. However, a major shift in microbial community composition was found following a single precipitation event. This shift in composition was associated with a rapid increase in CO 2 respiration and productivity, supporting the view that desert soil microbial communities respond rapidly to re-wetting and that this response may be the result of both taxon-specific selection and changes in the availability or accessibility of organic substrates. Recovery to quasi pre-disturbance community composition was achieved within one month after rainfall.

  5. Temporal dynamics of hot desert microbial communities reveal structural and functional responses to water input

    Energy Technology Data Exchange (ETDEWEB)

    Armstrong, Alacia; Valverde, Angel; Ramond, Jean-Baptiste; Makhalanyane, Thulani P.; Jansson, Janet K.; Hopkins, David W.; Aspray, Thomas J.; Seely, Mary; Trindade, Marla I.; Cowan, Don A.

    2016-09-29

    The temporal dynamics of desert soil microbial communities are poorly understood. Given the implications for ecosystem functioning under a global change scenario, a better understanding of desert microbial community stability is crucial. Here, we sampled soils in the central Namib Desert on sixteen different occasions over a one-year period. Using Illumina-based amplicon sequencing of the 16S rRNA gene, we found that α-diversity (richness) was more variable at a given sampling date (spatial variability) than over the course of one year (temporal variability). Community composition remained essentially unchanged across the first 10 months, indicating that spatial sampling might be more important than temporal sampling when assessing β-diversity patterns in desert soils. However, a major shift in microbial community composition was found following a single precipitation event. This shift in composition was associated with a rapid increase in CO2 respiration and productivity, supporting the view that desert soil microbial communities respond rapidly to re-wetting and that this response may be the result of both taxon-specific selection and changes in the availability or accessibility of organic substrates. Recovery to quasi pre-disturbance community composition was achieved within one month after rainfall.

  6. Quantitative Evaluation of Temporal Regularizers in Compressed Sensing Dynamic Contrast Enhanced MRI of the Breast

    Directory of Open Access Journals (Sweden)

    Dong Wang

    2017-01-01

    Full Text Available Purpose. Dynamic contrast enhanced magnetic resonance imaging (DCE-MRI is used in cancer imaging to probe tumor vascular properties. Compressed sensing (CS theory makes it possible to recover MR images from randomly undersampled k-space data using nonlinear recovery schemes. The purpose of this paper is to quantitatively evaluate common temporal sparsity-promoting regularizers for CS DCE-MRI of the breast. Methods. We considered five ubiquitous temporal regularizers on 4.5x retrospectively undersampled Cartesian in vivo breast DCE-MRI data: Fourier transform (FT, Haar wavelet transform (WT, total variation (TV, second-order total generalized variation (TGVα2, and nuclear norm (NN. We measured the signal-to-error ratio (SER of the reconstructed images, the error in tumor mean, and concordance correlation coefficients (CCCs of the derived pharmacokinetic parameters Ktrans (volume transfer constant and ve (extravascular-extracellular volume fraction across a population of random sampling schemes. Results. NN produced the lowest image error (SER: 29.1, while TV/TGVα2 produced the most accurate Ktrans (CCC: 0.974/0.974 and ve (CCC: 0.916/0.917. WT produced the highest image error (SER: 21.8, while FT produced the least accurate Ktrans (CCC: 0.842 and ve (CCC: 0.799. Conclusion. TV/TGVα2 should be used as temporal constraints for CS DCE-MRI of the breast.

  7. Discrimination of Dynamic Tactile Contact by Temporally Precise Event Sensing in Spiking Neuromorphic Networks.

    Science.gov (United States)

    Lee, Wang Wei; Kukreja, Sunil L; Thakor, Nitish V

    2017-01-01

    This paper presents a neuromorphic tactile encoding methodology that utilizes a temporally precise event-based representation of sensory signals. We introduce a novel concept where touch signals are characterized as patterns of millisecond precise binary events to denote pressure changes. This approach is amenable to a sparse signal representation and enables the extraction of relevant features from thousands of sensing elements with sub-millisecond temporal precision. We also proposed measures adopted from computational neuroscience to study the information content within the spiking representations of artificial tactile signals. Implemented on a state-of-the-art 4096 element tactile sensor array with 5.2 kHz sampling frequency, we demonstrate the classification of transient impact events while utilizing 20 times less communication bandwidth compared to frame based representations. Spiking sensor responses to a large library of contact conditions were also synthesized using finite element simulations, illustrating an 8-fold improvement in information content and a 4-fold reduction in classification latency when millisecond-precise temporal structures are available. Our research represents a significant advance, demonstrating that a neuromorphic spatiotemporal representation of touch is well suited to rapid identification of critical contact events, making it suitable for dynamic tactile sensing in robotic and prosthetic applications.

  8. Emergent dynamics of spatio-temporal chaos in a heterogeneous excitable medium.

    Science.gov (United States)

    Bittihn, Philip; Berg, Sebastian; Parlitz, Ulrich; Luther, Stefan

    2017-09-01

    Self-organized activation patterns in excitable media such as spiral waves and spatio-temporal chaos underlie dangerous cardiac arrhythmias. While the interaction of single spiral waves with different types of heterogeneity has been studied extensively, the effect of heterogeneity on fully developed spatio-temporal chaos remains poorly understood. We investigate how the complexity and stability properties of spatio-temporal chaos in the Bär-Eiswirth model of excitable media depend on the heterogeneity of the underlying medium. We employ different measures characterizing the chaoticity of the system and find that the spatial arrangement of multiple discrete lower excitability regions has a strong impact on the complexity of the dynamics. Varying the number, shape, and spatial arrangement of the heterogeneities, we observe strong emergent effects ranging from increases in chaoticity to the complete cessation of chaos, contrasting the expectation from the homogeneous behavior. The implications of our findings for the development and treatment of arrhythmias in the heterogeneous cardiac muscle are discussed.

  9. Temporal Microbial Community Dynamics in Microbial Electrolysis Cells – Influence of Acetate and Propionate Concentration

    KAUST Repository

    Rao, Hari Ananda

    2017-07-20

    Microbial electrolysis cells (MECs) are widely considered as a next generation wastewater treatment system. However, fundamental insight on the temporal dynamics of microbial communities associated with MEC performance under different organic types with varied loading concentrations is still unknown, nevertheless this knowledge is essential for optimizing this technology for real-scale applications. Here, the temporal dynamics of anodic microbial communities associated with MEC performance was examined at low (0.5 g COD/L) and high (4 g COD/L) concentrations of acetate or propionate, which are important intermediates of fermentation of municipal wastewaters and sludge. The results showed that acetate-fed reactors exhibited higher performance in terms of maximum current density (I: 4.25 ± 0.23 A/m), coulombic efficiency (CE: 95 ± 8%), and substrate degradation rate (98.8 ± 1.2%) than propionate-fed reactors (I: 2.7 ± 0.28 A/m; CE: 68 ± 9.5%; substrate degradation rate: 84 ± 13%) irrespective of the concentrations tested. Despite of the repeated sampling of the anodic biofilm over time, the high-concentration reactors demonstrated lower and stable performance in terms of current density (I: 1.1 ± 0.14 to 4.2 ± 0.21 A/m), coulombic efficiency (CE: 44 ± 4.1 to 103 ± 7.2%) and substrate degradation rate (64.9 ± 6.3 to 99.7 ± 0.5%), while the low-concentration reactors produced higher and dynamic performance (I: 1.1 ± 0.12 to 4.6 ± 0.1 A/m; CE: 52 ± 2.5 to 105 ± 2.7%; substrate degradation rate: 87.2 ± 0.2 to 99.9 ± 0.06%) with the different substrates tested. Correlating reactor\\'s performance with temporal dynamics of microbial communities showed that relatively similar anodic microbial community composition but with varying relative abundances was observed in all the reactors despite differences in the substrate and concentrations tested. Particularly, Geobacter was the predominant bacteria on the anode biofilm of all MECs over time suggesting its

  10. Evaluating complementary networks of restoration plantings for landscape-scale occurrence of temporally dynamic species.

    Science.gov (United States)

    Ikin, Karen; Tulloch, Ayesha; Gibbons, Philip; Ansell, Dean; Seddon, Julian; Lindenmayer, David

    2016-10-01

    Multibillion dollar investments in land restoration make it critical that conservation goals are achieved cost-effectively. Approaches developed for systematic conservation planning offer opportunities to evaluate landscape-scale, temporally dynamic biodiversity outcomes from restoration and improve on traditional approaches that focus on the most species-rich plantings. We investigated whether it is possible to apply a complementarity-based approach to evaluate the extent to which an existing network of restoration plantings meets representation targets. Using a case study of woodland birds of conservation concern in southeastern Australia, we compared complementarity-based selections of plantings based on temporally dynamic species occurrences with selections based on static species occurrences and selections based on ranking plantings by species richness. The dynamic complementarity approach, which incorporated species occurrences over 5 years, resulted in higher species occurrences and proportion of targets met compared with the static complementarity approach, in which species occurrences were taken at a single point in time. For equivalent cost, the dynamic complementarity approach also always resulted in higher average minimum percent occurrence of species maintained through time and a higher proportion of the bird community meeting representation targets compared with the species-richness approach. Plantings selected under the complementarity approaches represented the full range of planting attributes, whereas those selected under the species-richness approach were larger in size. Our results suggest that future restoration policy should not attempt to achieve all conservation goals within individual plantings, but should instead capitalize on restoration opportunities as they arise to achieve collective value of multiple plantings across the landscape. Networks of restoration plantings with complementary attributes of age, size, vegetation structure, and

  11. Temperamental correlates of disruptive behavior disorders in young children: preliminary findings.

    Science.gov (United States)

    Hirshfeld-Becker, Dina R; Biederman, Joseph; Faraone, Stephen V; Violette, Heather; Wrightsman, Jessica; Rosenbaum, Jerrold F

    2002-04-01

    Our objective was to test the hypothesis that temperamental behavioral disinhibition measured in early childhood would be associated with disruptive behavior disorders. We used variables from laboratory-based behavioral observations originally devised to assess behavioral inhibition to construct a theory-based a priori definition of "behavioral disinhibition" in 200 young children at-risk for panic disorder, depression, or both and 84 children of parents without anxiety or major depressive disorder. We then compared behaviorally disinhibited and nonbehaviorally disinhibited children on rates of DSM-III-R disorders and measures of academic and social dysfunction. Behavioral disinhibition was significantly associated with higher rates of disruptive behavior disorders and mood disorders. Children with behavioral disinhibition were significantly more likely than nondisinhibited, noninhibited children to have attention-deficit/hyperactivity disorder (ADHD) and to have comorbid mood and disruptive behavior disorders. Moreover, disinhibited children had lower Global Assessment of Functioning Scale scores and were more likely to have been in special classes and to have problems with school behavior and leisure activities. These results suggest that behavioral disinhibition may represent a temperamental precursor to disruptive behavior problems, particularly ADHD. Longitudinal studies using behavioral assessments of behavioral disinhibition are needed to confirm these findings.

  12. Somatic growth dynamics of West Atlantic hawksbill sea turtles: a spatio-temporal perspective

    Science.gov (United States)

    Bjorndal, Karen A.; Chaloupka, Milani; Saba, Vincent S.; Diez, Carlos E.; van Dam, Robert P.; Krueger, Barry H.; Horrocks, Julia A.; Santos, Armando J.B.; Bellini, Cláudio; Marcovaldi, Maria A.G.; Nava, Mabel; Willis, Sue; Godley, Brendan J.; Gore, Shannon; Hawkes, Lucy A.; McGowan, Andrew; Witt, Matthew J.; Stringell, Thomas B.; Sanghera, Amdeep; Richardson, Peter B.; Broderick, Annette C.; Phillips, Quinton; Calosso, Marta C.; Claydon, John A.B.; Blumenthal, Janice; Moncada, Felix; Nodarse, Gonzalo; Medina, Yosvani; Dunbar, Stephen G.; Wood, Lawrence D.; Lagueux, Cynthia J.; Campbell, Cathi L.; Meylan, Anne B.; Meylan, Peter A.; Burns Perez, Virginia R.; Coleman, Robin A.; Strindberg, Samantha; Guzmán-H, Vicente; Hart, Kristen M.; Cherkiss, Michael S.; Hillis-Starr, Zandy; Lundgren, Ian; Boulon, Ralf H.; Connett, Stephen; Outerbridge, Mark E.; Bolten, Alan B.

    2016-01-01

    Somatic growth dynamics are an integrated response to environmental conditions. Hawksbill sea turtles (Eretmochelys imbricata) are long-lived, major consumers in coral reef habitats that move over broad geographic areas (hundreds to thousands of kilometers). We evaluated spatio-temporal effects on hawksbill growth dynamics over a 33-yr period and 24 study sites throughout the West Atlantic and explored relationships between growth dynamics and climate indices. We compiled the largest ever data set on somatic growth rates for hawksbills – 3541 growth increments from 1980 to 2013. Using generalized additive mixed model analyses, we evaluated 10 covariates, including spatial and temporal variation, that could affect growth rates. Growth rates throughout the region responded similarly over space and time. The lack of a spatial effect or spatio-temporal interaction and the very strong temporal effect reveal that growth rates in West Atlantic hawksbills are likely driven by region-wide forces. Between 1997 and 2013, mean growth rates declined significantly and steadily by 18%. Regional climate indices have significant relationships with annual growth rates with 0- or 1-yr lags: positive with the Multivariate El Niño Southern Oscillation Index (correlation = 0.99) and negative with Caribbean sea surface temperature (correlation = −0.85). Declines in growth rates between 1997 and 2013 throughout the West Atlantic most likely resulted from warming waters through indirect negative effects on foraging resources of hawksbills. These climatic influences are complex. With increasing temperatures, trajectories of decline of coral cover and availability in reef habitats of major prey species of hawksbills are not parallel. Knowledge of how choice of foraging habitats, prey selection, and prey abundance are affected by warming water temperatures is needed to understand how climate change will affect productivity of consumers that live in association with coral reefs. Main

  13. Near equilibrium dynamics and one-dimensional spatial—temporal structures of polar active liquid crystals

    International Nuclear Information System (INIS)

    Yang Xiao-Gang; Wang Qi; Forest, M. Gregory

    2014-01-01

    We systematically explore near equilibrium, flow-driven, and flow-activity coupled dynamics of polar active liquid crystals using a continuum model. Firstly, we re-derive the hydrodynamic model to ensure the thermodynamic laws are obeyed and elastic stresses and forces are consistently accounted. We then carry out a linear stability analysis about constant steady states to study near equilibrium dynamics around the steady states, revealing long-wave instability inherent in this model system and how active parameters in the model affect the instability. We then study model predictions for one-dimensional (1D) spatial—temporal structures of active liquid crystals in a channel subject to physical boundary conditions. We discuss the model prediction in two selected regimes, one is the viscous stress dominated regime, also known as the flow-driven regime, while the other is the full regime, in which all active mechanisms are included. In the viscous stress dominated regime, the polarity vector is driven by the prescribed flow field. Dynamics depend sensitively on the physical boundary condition and the type of the driven flow field. Bulk-dominated temporal periodic states and spatially homogeneous states are possible under weak anchoring conditions while spatially inhomogeneous states exist under strong anchoring conditions. In the full model, flow-orientation interaction generates a host of planar as well as out-of-plane spatial—temporal structures related to the spontaneous flows due to the molecular self-propelled motion. These results provide contact with the recent literature on active nematic suspensions. In addition, symmetry breaking patterns emerge as the additional active viscous stress due to the polarity vector is included in the force balance. The inertia effect is found to limit the long-time survival of spatial structures to those with small wave numbers, i.e., an asymptotic coarsening to long wave structures. A rich set of mechanisms for generating

  14. Fluid consumption and taste novelty determines transcription temporal dynamics in the gustatory cortex.

    Science.gov (United States)

    Inberg, Sharon; Jacob, Eyal; Elkobi, Alina; Edry, Efrat; Rappaport, Akiva; Simpson, T Ian; Armstrong, J Douglas; Shomron, Noam; Pasmanik-Chor, Metsada; Rosenblum, Kobi

    2016-02-09

    Novel taste memories, critical for animal survival, are consolidated to form long term memories which are dependent on translation regulation in the gustatory cortex (GC) hours following acquisition. However, the role of transcription regulation in the process is unknown. Here, we report that transcription in the GC is necessary for taste learning in rats, and that drinking and its consequences, as well as the novel taste experience, affect transcription in the GC during taste memory consolidation. We show differential effects of learning on temporal dynamics in set of genes in the GC, including Arc/Arg3.1, known to regulate the homeostasis of excitatory synapses. We demonstrate that in taste learning, transcription programs were activated following the physiological responses (i.e., fluid consumption following a water restriction regime, reward, arousal of the animal, etc.) and the specific information about a given taste (i.e., taste novelty). Moreover, the cortical differential prolonged kinetics of mRNA following novel versus familiar taste learning may represent additional novelty related molecular response, where not only the total amount, but also the temporal dynamics of transcription is modulated by sensory experience of novel information.

  15. Left or right? Lateralizing temporal lobe epilepsy by dynamic amygdala fMRI.

    Science.gov (United States)

    Ives-Deliperi, Victoria; Butler, James Thomas; Jokeit, Hennric

    2017-05-01

    In this case series, the findings of 85 functional MRI studies employing a dynamic fearful face paradigm are reported. Previous findings have shown the paradigm to generate bilateral amygdala activations in healthy subjects and unilateral activations in patients with MTLE, in the contralateral hemisphere to seizure origin. Such findings suggest ipsilateral limbic pathology and offer collateral evidence in lateralizing MTLE. The series includes 60 patients with TLE, 12 patients with extra-temporal lobe epilepsy, and 13 healthy controls. Functional MRI studies using a 1.5T scanner were conducted over a three-year period at a single epilepsy center and individual results were compared with EEG findings. In the cohort of unilateral TLE patients, lateralized activations of the amygdala were concordant with EEG findings in 76% of patients (77% lTLE, 74% rTLE). The differences in the mean lateralized indices of the lTLE, rTLE, and healthy control groups were all statistically significant. Lateralized amygdala activations were concordant with EEG findings in only 31% of the 12 patients with extra-temporal lobe epilepsy and bilateral amygdala activations were generated in all but one of the healthy control subjects. This case series further endorses the utility of the dynamic fearful face functional MRI paradigm using the widely available 1.5T as an adjunctive investigation to lateralize TLE. Copyright © 2017 Elsevier Inc. All rights reserved.

  16. Temporal dynamics of categorization: Forgetting as the basis of abstraction and generalization

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    Haley eVlach

    2014-09-01

    Full Text Available Historically, models of categorization have focused on how learners track frequencies and co-occurrence information to abstract relevant category features for generalization. The current study takes a different approach by examining how the temporal dynamics of categorization affect abstraction and generalization. In the learning phase of the experiment, all relevant category features were presented an equal number of times across category exemplars. However, the relevant features were presented on one of two learning schedules: massed or interleaved. At a series of immediate and delayed tests, learners were asked to generalize to novel exemplars that contained massed features, interleaved features, or all novel features. The results of this experiment revealed that, at an immediate test, learners more readily generalized based upon features presented on a massed schedule. Conversely, at a delayed test, learners more readily generalized based upon features presented on an interleaved schedule, until information was no longer readily retrievable from memory. These findings suggest that forgetting and retrieval processes engendered by the temporal dynamics of learning are used as a basis of abstraction, implicating forgetting as a central mechanism of generalization.

  17. Spatial and temporal dynamics of the genetic organization of small mammal populations

    International Nuclear Information System (INIS)

    Smith, M.H.; Manlove, M.N.; Joule, J.

    1978-01-01

    A functional population is a group of organisms and their offspring that contributes to a common gene pool within a certain area and time period. It is also the unit of evolution and should be viewed both in quantitative and qualitative terms. Selection, drift, dispersal, and mutation can alter the composition of populations. Spatial heterogeneity in allele frequencies argues for a conceptual model that has a series of relatively small populations semi-isolated from one another. Because of the relatively high levels of genetic variability characteristic of most mammalian species, significant amounts of gene flow between these spatially subdivided populations must occur when longer time periods are considered. Fluctuations in the genetic structure of populations seem to be important in altering the fitness of the individuals within the populations. The interaction of populations through gene flow is important in changing the levels of intrapopulational genetic variability. Populations can be characterized as existing on a continuum from relatively stable to unstable numbers and by other associated changes in their characteristics. Temporal changes in allele frequency occur in a variety of mammals. Conceptually, a species can be viewed as a series of dynamic populations that vary in numbers and quality in both a spatial and temporal context even over short distances and time periods. Short term changes in the quality of individuals in a population can be important in altering the short term dynamics of a population

  18. Influence of fluvial environments on sediment archiving processes and temporal pollutant dynamics (Upper Loire River, France).

    Science.gov (United States)

    Dhivert, E; Grosbois, C; Rodrigues, S; Desmet, M

    2015-02-01

    Floodplains are often cored to build long-term pollutant trends at the basin scale. To highlight the influences of depositional environments on archiving processes, aggradation rates, archived trace element signals and vertical redistribution processes, two floodplain cores were sampled near in two different environments of the Upper Loire River (France): (i) a river bank ridge and (ii) a paleochannel connected by its downstream end. The base of the river bank core is composed of sandy sediments from the end of the Little Ice Age (late 18th century). This composition corresponds to a proximal floodplain aggradation (sediments that settled in the distal floodplain. In this distal floodplain environment, the aggradation rate depends on the topography and connection degree to the river channel. The temporal dynamics of anthropogenic trace element enrichments recorded in the distal floodplain are initially synchronous and present similar levels. Although the river bank core shows general temporal trends, the paleochannel core has a better resolution for short-time variations of trace element signals. After local water depth regulation began in the early 1930s, differences of connection degree were enhanced between the two cores. Therefore, large trace element signal divergences are recorded across the floodplain. The paleochannel core shows important temporal variations of enrichment levels from the 1930s to the coring date. However, the river bank core has no significant temporal variations of trace element enrichments and lower contamination levels because of a lower deposition of contaminated sediments and a pedogenetic trace elements redistribution. Copyright © 2014 Elsevier B.V. All rights reserved.

  19. Exploring spatial-temporal dynamics of fire regime features in mainland Spain

    Science.gov (United States)

    Jiménez-Ruano, Adrián; Rodrigues Mimbrero, Marcos; de la Riva Fernández, Juan

    2017-10-01

    This paper explores spatial-temporal dynamics in fire regime features, such as fire frequency, burnt area, large fires and natural- and human-caused fires, as an essential part of fire regime characterization. Changes in fire features are analysed at different spatial - regional and provincial/NUTS3 - levels, together with summer and winter temporal scales, using historical fire data from Spain for the period 1974-2013. Temporal shifts in fire features are investigated by means of change point detection procedures - Pettitt test, AMOC (at most one change), PELT (pruned exact linear time) and BinSeg (binary segmentation) - at a regional level to identify changes in the time series of the features. A trend analysis was conducted using the Mann-Kendall and Sen's slope tests at both the regional and NUTS3 level. Finally, we applied a principal component analysis (PCA) and varimax rotation to trend outputs - mainly Sen's slope values - to summarize overall temporal behaviour and to explore potential links in the evolution of fire features. Our results suggest that most fire features show remarkable shifts between the late 1980s and the first half of the 1990s. Mann-Kendall outputs revealed negative trends in the Mediterranean region. Results from Sen's slope suggest high spatial and intra-annual variability across the study area. Fire activity related to human sources seems to be experiencing an overall decrease in the northwestern provinces, particularly pronounced during summer. Similarly, the Hinterland and the Mediterranean coast are gradually becoming less fire affected. Finally, PCA enabled trends to be synthesized into four main components: winter fire frequency (PC1), summer burnt area (PC2), large fires (PC3) and natural fires (PC4).

  20. Exploring spatial–temporal dynamics of fire regime features in mainland Spain

    Directory of Open Access Journals (Sweden)

    A. Jiménez-Ruano

    2017-10-01

    Full Text Available This paper explores spatial–temporal dynamics in fire regime features, such as fire frequency, burnt area, large fires and natural- and human-caused fires, as an essential part of fire regime characterization. Changes in fire features are analysed at different spatial – regional and provincial/NUTS3 – levels, together with summer and winter temporal scales, using historical fire data from Spain for the period 1974–2013. Temporal shifts in fire features are investigated by means of change point detection procedures – Pettitt test, AMOC (at most one change, PELT (pruned exact linear time and BinSeg (binary segmentation – at a regional level to identify changes in the time series of the features. A trend analysis was conducted using the Mann–Kendall and Sen's slope tests at both the regional and NUTS3 level. Finally, we applied a principal component analysis (PCA and varimax rotation to trend outputs – mainly Sen's slope values – to summarize overall temporal behaviour and to explore potential links in the evolution of fire features. Our results suggest that most fire features show remarkable shifts between the late 1980s and the first half of the 1990s. Mann–Kendall outputs revealed negative trends in the Mediterranean region. Results from Sen's slope suggest high spatial and intra-annual variability across the study area. Fire activity related to human sources seems to be experiencing an overall decrease in the northwestern provinces, particularly pronounced during summer. Similarly, the Hinterland and the Mediterranean coast are gradually becoming less fire affected. Finally, PCA enabled trends to be synthesized into four main components: winter fire frequency (PC1, summer burnt area (PC2, large fires (PC3 and natural fires (PC4.

  1. Temporal dynamics of distinct CA1 cell populations during unconscious state induced by ketamine.

    Directory of Open Access Journals (Sweden)

    Hui Kuang

    2010-12-01

    Full Text Available Ketamine is a widely used dissociative anesthetic which can induce some psychotic-like symptoms and memory deficits in some patients during the post-operative period. To understand its effects on neural population dynamics in the brain, we employed large-scale in vivo ensemble recording techniques to monitor the activity patterns of simultaneously recorded hippocampal CA1 pyramidal cells and various interneurons during several conscious and unconscious states such as awake rest, running, slow wave sleep, and ketamine-induced anesthesia. Our analyses reveal that ketamine induces distinct oscillatory dynamics not only in pyramidal cells but also in at least seven different types of CA1 interneurons including putative basket cells, chandelier cells, bistratified cells, and O-LM cells. These emergent unique oscillatory dynamics may very well reflect the intrinsic temporal relationships within the CA1 circuit. It is conceivable that systematic characterization of network dynamics may eventually lead to better understanding of how ketamine induces unconsciousness and consequently alters the conscious mind.

  2. Agent-based modeling of autophagy reveals emergent regulatory behavior of spatio-temporal autophagy dynamics.

    Science.gov (United States)

    Börlin, Christoph S; Lang, Verena; Hamacher-Brady, Anne; Brady, Nathan R

    2014-09-10

    Autophagy is a vesicle-mediated pathway for lysosomal degradation, essential under basal and stressed conditions. Various cellular components, including specific proteins, protein aggregates, organelles and intracellular pathogens, are targets for autophagic degradation. Thereby, autophagy controls numerous vital physiological and pathophysiological functions, including cell signaling, differentiation, turnover of cellular components and pathogen defense. Moreover, autophagy enables the cell to recycle cellular components to metabolic substrates, thereby permitting prolonged survival under low nutrient conditions. Due to the multi-faceted roles for autophagy in maintaining cellular and organismal homeostasis and responding to diverse stresses, malfunction of autophagy contributes to both chronic and acute pathologies. We applied a systems biology approach to improve the understanding of this complex cellular process of autophagy. All autophagy pathway vesicle activities, i.e. creation, movement, fusion and degradation, are highly dynamic, temporally and spatially, and under various forms of regulation. We therefore developed an agent-based model (ABM) to represent individual components of the autophagy pathway, subcellular vesicle dynamics and metabolic feedback with the cellular environment, thereby providing a framework to investigate spatio-temporal aspects of autophagy regulation and dynamic behavior. The rules defining our ABM were derived from literature and from high-resolution images of autophagy markers under basal and activated conditions. Key model parameters were fit with an iterative method using a genetic algorithm and a predefined fitness function. From this approach, we found that accurate prediction of spatio-temporal behavior required increasing model complexity by implementing functional integration of autophagy with the cellular nutrient state. The resulting model is able to reproduce short-term autophagic flux measurements (up to 3

  3. A Markov model for the temporal dynamics of balanced random networks of finite size

    Science.gov (United States)

    Lagzi, Fereshteh; Rotter, Stefan

    2014-01-01

    The balanced state of recurrent networks of excitatory and inhibitory spiking neurons is characterized by fluctuations of population activity about an attractive fixed point. Numerical simulations show that these dynamics are essentially nonlinear, and the intrinsic noise (self-generated fluctuations) in networks of finite size is state-dependent. Therefore, stochastic differential equations with additive noise of fixed amplitude cannot provide an adequate description of the stochastic dynamics. The noise model should, rather, result from a self-consistent description of the network dynamics. Here, we consider a two-state Markovian neuron model, where spikes correspond to transitions from the active state to the refractory state. Excitatory and inhibitory input to this neuron affects the transition rates between the two states. The corresponding nonlinear dependencies can be identified directly from numerical simulations of networks of leaky integrate-and-fire neurons, discretized at a time resolution in the sub-millisecond range. Deterministic mean-field equations, and a noise component that depends on the dynamic state of the network, are obtained from this model. The resulting stochastic model reflects the behavior observed in numerical simulations quite well, irrespective of the size of the network. In particular, a strong temporal correlation between the two populations, a hallmark of the balanced state in random recurrent networks, are well represented by our model. Numerical simulations of such networks show that a log-normal distribution of short-term spike counts is a property of balanced random networks with fixed in-degree that has not been considered before, and our model shares this statistical property. Furthermore, the reconstruction of the flow from simulated time series suggests that the mean-field dynamics of finite-size networks are essentially of Wilson-Cowan type. We expect that this novel nonlinear stochastic model of the interaction between

  4. Spatio-temporal dynamics of the penetration resistance of recultivated soils formed after open cast mining

    Directory of Open Access Journals (Sweden)

    A. V. Zhukov

    2016-01-01

    Full Text Available On the basis of studying the spatio-temporal dynamics of soil penetration resistance we proved the existence of the technozem ecomorphs as above horizon soil formations. Research was carried out at a research center for study of recultivation processes in Ordzhonikidze city. Measurement of soils penetration was made in field conditions using an Eijkelkamp penetrometer on a regular grid at depths of up to50 cmwith intervals of5 cm. Calculation of average values and degrees of variation was performed by means of descriptive statistical tools. The extent of soil penetration spatial dependence was assessed and the existence of ecomorphs was proved by means of geostatistical analysis. The degree of associativity of spatial distribution of indicators of a soil body in different years of research was established by means of correlation analysis. The level of variation in space and in time of  technozem penetration generated on loess-like loams, grey-green, red-brown clays, and also pedozems was revealed. The degree of spatial dependence of  technozem penetration within soil layers and also the linear sizes of ecomorphs as above horizon soil structures was established. The time dynamics of  penetration of various recultozems were described. As a result of research into the spatio-temporal dynamics of penetration of technozems, data confirming the hypothesis of the existence of ecomorphs as above horizon morphological soil formations were obtained. An ecomorphic approach to the study of the morphological structure of technozems is proposed. The comparative characteristics of ecomorphs from various types of technozem are presented. The results obtained solve the problem of combining the higher and lowest levels in the hierarchical system of soil organisation as a natural body, which should raise the efficiency of the analysis of relations of morphological elements as a basis for detailed reconstruction of recultivation processes, soil formation, and

  5. Frontiers in Fluctuation Spectroscopy: Measuring protein dynamics and protein spatio-temporal connectivity

    Science.gov (United States)

    Digman, Michelle

    Fluorescence fluctuation spectroscopy has evolved from single point detection of molecular diffusion to a family of microscopy imaging correlation tools (i.e. ICS, RICS, STICS, and kICS) useful in deriving spatial-temporal dynamics of proteins in living cells The advantage of the imaging techniques is the simultaneous measurement of all points in an image with a frame rate that is increasingly becoming faster with better sensitivity cameras and new microscopy modalities such as the sheet illumination technique. A new frontier in this area is now emerging towards a high level of mapping diffusion rates and protein dynamics in the 2 and 3 dimensions. In this talk, I will discuss the evolution of fluctuation analysis from the single point source to mapping diffusion in whole cells and the technology behind this technique. In particular, new methods of analysis exploit correlation of molecular fluctuations originating from measurement of fluctuation correlations at distant points (pair correlation analysis) and methods that exploit spatial averaging of fluctuations in small regions (iMSD). For example the pair correlation fluctuation (pCF) analyses done between adjacent pixels in all possible radial directions provide a window into anisotropic molecular diffusion. Similar to the connectivity atlas of neuronal connections from the MRI diffusion tensor imaging these new tools will be used to map the connectome of protein diffusion in living cells. For biological reaction-diffusion systems, live single cell spatial-temporal analysis of protein dynamics provides a mean to observe stochastic biochemical signaling in the context of the intracellular environment which may lead to better understanding of cancer cell invasion, stem cell differentiation and other fundamental biological processes. National Institutes of Health Grant P41-RRO3155.

  6. The Emergence of Visual Awareness: Temporal Dynamics in Relation to Task and Mask Type

    Science.gov (United States)

    Kiefer, Markus; Kammer, Thomas

    2017-01-01

    One aspect of consciousness phenomena, the temporal emergence of visual awareness, has been subject of a controversial debate. How can visual awareness, that is the experiential quality of visual stimuli, be characterized best? Is there a sharp discontinuous or dichotomous transition between unaware and fully aware states, or does awareness emerge gradually encompassing intermediate states? Previous studies yielded conflicting results and supported both dichotomous and gradual views. It is well conceivable that these conflicting results are more than noise, but reflect the dynamic nature of the temporal emergence of visual awareness. Using a psychophysical approach, the present research tested whether the emergence of visual awareness is context-dependent with a temporal two-alternative forced choice task. During backward masking of word targets, it was assessed whether the relative temporal sequence of stimulus thresholds is modulated by the task (stimulus presence, letter case, lexical decision, and semantic category) and by mask type. Four masks with different similarity to the target features were created. Psychophysical functions were then fitted to the accuracy data in the different task conditions as a function of the stimulus mask SOA in order to determine the inflection point (conscious threshold of each feature) and slope of the psychophysical function (transition from unaware to aware within each feature). Depending on feature-mask similarity, thresholds in the different tasks were highly dispersed suggesting a graded transition from unawareness to awareness or had less differentiated thresholds indicating that clusters of features probed by the tasks quite simultaneously contribute to the percept. The latter observation, although not compatible with the notion of a sharp all-or-none transition between unaware and aware states, suggests a less gradual or more discontinuous emergence of awareness. Analyses of slopes of the fitted psychophysical functions

  7. Application of dynamic susceptibility contrast-enhanced perfusion in temporal lobe epilepsy

    Energy Technology Data Exchange (ETDEWEB)

    Xing, Wu; Wang, Xiaoyi; Xie, Fangfang; Liao, Weihua [Dept. of Radiology, Xiangya Hospital of Central South Univ., Changsha (China)], e-mail: doctoring@sina.com

    2013-02-15

    Background: Accurately locatithe epileptogenic focus in temporal lobe epilepsy (TLE) is important in clinical practice. Single-photon emission computed tomography (SPECT) and positron-emission tomography (PET) have been widely used in the lateralization of TLE, but both have limitations. Magnetic resonance perfusion imaging can accurately and reliably reflect differences in cerebral blood flow and volume. Purpose: To investigate the diagnostic value of dynamic susceptibility contrast-enhanced (DSC) perfusion magnetic resonance imaging (MRI) in the lateralization of the epileptogenic focus in TLE. Material and Methods: Conventional MRI and DSC-MRI scanning was performed in 20 interictal cases of TLE and 20 healthy volunteers. The relative cerebral blood volume (rCBV) and relative cerebral blood flow (rCBF) of the bilateral mesial temporal lobes of the TLE cases and healthy control groups were calculated. The differences in the perfusion asymmetry indices (AIs), derived from the rCBV and rCBF of the bilateral mesial temporal lobes, were pared between the two groups. Results: In the control group, there were no statistically significant differences between the left and right sides in terms of rCBV (left 1.55 {+-} 0.32, right 1.57 {+-} 0.28) or rCBF (left 99.00 {+-} 24.61, right 100.38 {+-} 23.46) of the bilateral mesial temporal lobes. However, in the case group the ipsilateral rCBV and rCBF values (1.75 {+-} 0.64 and 96.35 {+-} 22.63, respectively) were markedly lower than those of the contralateral side (2.01 {+-} 0.79 and 108.56 {+-} 26.92; P < 0.05). Both the AI of the rCBV (AIrCBV; 13.03 {+-} 10.33) and the AI of the rCBF (AIrCBF; 11.24 {+-} 8.70) of the case group were significantly higher than that of the control group (AIrCBV 5.55 {+-} 3.74, AIrCBF 5.12 {+-} 3.48; P < 0.05). The epileptogenic foci of nine patients were correctly lateralized using the 95th percentile of the AIrCBV and AIrCBF of the control group as the normal upper limits. Conclusion: In

  8. Application of dynamic susceptibility contrast-enhanced perfusion in temporal lobe epilepsy

    International Nuclear Information System (INIS)

    Xing, Wu; Wang, Xiaoyi; Xie, Fangfang; Liao, Weihua

    2013-01-01

    Background: Accurately locatithe epileptogenic focus in temporal lobe epilepsy (TLE) is important in clinical practice. Single-photon emission computed tomography (SPECT) and positron-emission tomography (PET) have been widely used in the lateralization of TLE, but both have limitations. Magnetic resonance perfusion imaging can accurately and reliably reflect differences in cerebral blood flow and volume. Purpose: To investigate the diagnostic value of dynamic susceptibility contrast-enhanced (DSC) perfusion magnetic resonance imaging (MRI) in the lateralization of the epileptogenic focus in TLE. Material and Methods: Conventional MRI and DSC-MRI scanning was performed in 20 interictal cases of TLE and 20 healthy volunteers. The relative cerebral blood volume (rCBV) and relative cerebral blood flow (rCBF) of the bilateral mesial temporal lobes of the TLE cases and healthy control groups were calculated. The differences in the perfusion asymmetry indices (AIs), derived from the rCBV and rCBF of the bilateral mesial temporal lobes, were pared between the two groups. Results: In the control group, there were no statistically significant differences between the left and right sides in terms of rCBV (left 1.55 ± 0.32, right 1.57 ± 0.28) or rCBF (left 99.00 ± 24.61, right 100.38 ± 23.46) of the bilateral mesial temporal lobes. However, in the case group the ipsilateral rCBV and rCBF values (1.75 ± 0.64 and 96.35 ± 22.63, respectively) were markedly lower than those of the contralateral side (2.01 ± 0.79 and 108.56 ± 26.92; P < 0.05). Both the AI of the rCBV (AIrCBV; 13.03 ± 10.33) and the AI of the rCBF (AIrCBF; 11.24 ± 8.70) of the case group were significantly higher than that of the control group (AIrCBV 5.55 ± 3.74, AIrCBF 5.12 ± 3.48; P < 0.05). The epileptogenic foci of nine patients were correctly lateralized using the 95th percentile of the AIrCBV and AIrCBF of the control group as the normal upper limits. Conclusion: In patients with TLE interictal

  9. A Transactional Model of Temperamental Development: Evidence of a Relationship between Child Temperament and Maternal Stress over Five Years

    Science.gov (United States)

    Pesonen, Anu-Katriina; Raikkonen, Katri; Heinonen, Kati; Komsi, Niina; Jarvenpaa, Anna-Liisa; Strandberg, Timo

    2008-01-01

    Although there is growing consensus that parental stress is a risk factor in child development, longitudinal studies of its effects are few. This study tested a sample of 231 mother-child dyads in terms of whether the relations between the global experience of stress in mothers (perceived stress scale) and child temperamental characteristics…

  10. Hotspots of Community Change: Temporal Dynamics Are Spatially Variable in Understory Plant Composition of a California Oak Woodland.

    Directory of Open Access Journals (Sweden)

    Erica N Spotswood

    Full Text Available Community response to external drivers such climate and disturbance can lead to fluctuations in community composition, or to directional change. Temporal dynamics can be influenced by a combination of drivers operating at multiple spatial scales, including external landscape scale drivers, local abiotic conditions, and local species pools. We hypothesized that spatial variation in these factors can create heterogeneity in temporal dynamics within landscapes. We used understory plant species composition from an 11 year dataset from a California oak woodland to compare plots where disturbance was experimentally manipulated with the removal of livestock grazing and a prescribed burn. We quantified three properties of temporal variation: compositional change (reflecting the appearance and disappearance of species, temporal fluctuation, and directional change. Directional change was related most strongly to disturbance type, and was highest at plots where grazing was removed during the study. Temporal fluctuations, compositional change, and directional change were all related to intrinsic abiotic factors, suggesting that some locations are more responsive to external drivers than others. Temporal fluctuations and compositional change were linked to local functional composition, indicating that environmental filters can create subsets of the local species pool that do not respond in the same way to external drivers. Temporal dynamics are often assumed to be relatively static at the landscape scale, provided disturbance and climate are continuous. This study shows that local and landscape scale factors jointly influence temporal dynamics creating hotspots that are particularly responsive to climate and disturbance. Thus, adequate predictions of response to disturbance or to changing climate will only be achieved by considering how factors at multiple spatial scales influence community resilience and recovery.

  11. Hotspots of Community Change: Temporal Dynamics Are Spatially Variable in Understory Plant Composition of a California Oak Woodland.

    Science.gov (United States)

    Spotswood, Erica N; Bartolome, James W; Allen-Diaz, Barbara

    2015-01-01

    Community response to external drivers such climate and disturbance can lead to fluctuations in community composition, or to directional change. Temporal dynamics can be influenced by a combination of drivers operating at multiple spatial scales, including external landscape scale drivers, local abiotic conditions, and local species pools. We hypothesized that spatial variation in these factors can create heterogeneity in temporal dynamics within landscapes. We used understory plant species composition from an 11 year dataset from a California oak woodland to compare plots where disturbance was experimentally manipulated with the removal of livestock grazing and a prescribed burn. We quantified three properties of temporal variation: compositional change (reflecting the appearance and disappearance of species), temporal fluctuation, and directional change. Directional change was related most strongly to disturbance type, and was highest at plots where grazing was removed during the study. Temporal fluctuations, compositional change, and directional change were all related to intrinsic abiotic factors, suggesting that some locations are more responsive to external drivers than others. Temporal fluctuations and compositional change were linked to local functional composition, indicating that environmental filters can create subsets of the local species pool that do not respond in the same way to external drivers. Temporal dynamics are often assumed to be relatively static at the landscape scale, provided disturbance and climate are continuous. This study shows that local and landscape scale factors jointly influence temporal dynamics creating hotspots that are particularly responsive to climate and disturbance. Thus, adequate predictions of response to disturbance or to changing climate will only be achieved by considering how factors at multiple spatial scales influence community resilience and recovery.

  12. Quadratic temporal finite element method for linear elastic structural dynamics based on mixed convolved action

    International Nuclear Information System (INIS)

    Kim, Jin Kyu; Kim, Dong Keon

    2016-01-01

    A common approach for dynamic analysis in current practice is based on a discrete time-integration scheme. This approach can be largely attributed to the absence of a true variational framework for initial value problems. To resolve this problem, a new stationary variational principle was recently established for single-degree-of-freedom oscillating systems using mixed variables, fractional derivatives and convolutions of convolutions. In this mixed convolved action, all the governing differential equations and initial conditions are recovered from the stationarity of a single functional action. Thus, the entire description of linear elastic dynamical systems is encapsulated. For its practical application to structural dynamics, this variational formalism is systemically extended to linear elastic multidegree- of-freedom systems in this study, and a corresponding weak form is numerically implemented via a quadratic temporal finite element method. The developed numerical method is symplectic and unconditionally stable with respect to a time step for the underlying conservative system. For the forced-damped vibration, a three-story shear building is used as an example to investigate the performance of the developed numerical method, which provides accurate results with good convergence characteristics

  13. Population responses to environmental change in a tropical ant: the interaction of spatial and temporal dynamics.

    Science.gov (United States)

    Jackson, Doug; Vandermeer, John; Perfecto, Ivette; Philpott, Stacy M

    2014-01-01

    Spatial structure can have a profound, but often underappreciated, effect on the temporal dynamics of ecosystems. Here we report on a counterintuitive increase in the population of a tree-nesting ant, Azteca sericeasur, in response to a drastic reduction in the number of potential nesting sites. This surprising result is comprehensible when viewed in the context of the self-organized spatial dynamics of the ants and their effect on the ants' dispersal-limited natural enemies. Approximately 30% of the trees in the study site, a coffee agroecosystem in southern Mexico, were pruned or felled over a two-year period, and yet the abundance of the ant nests more than doubled over the seven-year study. Throughout the transition, the spatial distribution of the ants maintained a power-law distribution - a signal of spatial self organization - but the local clustering of the nests was reduced post-pruning. A cellular automata model incorporating the changed spatial structure of the ants and the resulting partial escape from antagonists reproduced the observed increase in abundance, highlighting how self-organized spatial dynamics can profoundly influence the responses of ecosystems to perturbations.

  14. Population responses to environmental change in a tropical ant: the interaction of spatial and temporal dynamics.

    Directory of Open Access Journals (Sweden)

    Doug Jackson

    Full Text Available Spatial structure can have a profound, but often underappreciated, effect on the temporal dynamics of ecosystems. Here we report on a counterintuitive increase in the population of a tree-nesting ant, Azteca sericeasur, in response to a drastic reduction in the number of potential nesting sites. This surprising result is comprehensible when viewed in the context of the self-organized spatial dynamics of the ants and their effect on the ants' dispersal-limited natural enemies. Approximately 30% of the trees in the study site, a coffee agroecosystem in southern Mexico, were pruned or felled over a two-year period, and yet the abundance of the ant nests more than doubled over the seven-year study. Throughout the transition, the spatial distribution of the ants maintained a power-law distribution - a signal of spatial self organization - but the local clustering of the nests was reduced post-pruning. A cellular automata model incorporating the changed spatial structure of the ants and the resulting partial escape from antagonists reproduced the observed increase in abundance, highlighting how self-organized spatial dynamics can profoundly influence the responses of ecosystems to perturbations.

  15. Quadratic temporal finite element method for linear elastic structural dynamics based on mixed convolved action

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jin Kyu [School of Architecture and Architectural Engineering, Hanyang University, Ansan (Korea, Republic of); Kim, Dong Keon [Dept. of Architectural Engineering, Dong A University, Busan (Korea, Republic of)

    2016-09-15

    A common approach for dynamic analysis in current practice is based on a discrete time-integration scheme. This approach can be largely attributed to the absence of a true variational framework for initial value problems. To resolve this problem, a new stationary variational principle was recently established for single-degree-of-freedom oscillating systems using mixed variables, fractional derivatives and convolutions of convolutions. In this mixed convolved action, all the governing differential equations and initial conditions are recovered from the stationarity of a single functional action. Thus, the entire description of linear elastic dynamical systems is encapsulated. For its practical application to structural dynamics, this variational formalism is systemically extended to linear elastic multidegree- of-freedom systems in this study, and a corresponding weak form is numerically implemented via a quadratic temporal finite element method. The developed numerical method is symplectic and unconditionally stable with respect to a time step for the underlying conservative system. For the forced-damped vibration, a three-story shear building is used as an example to investigate the performance of the developed numerical method, which provides accurate results with good convergence characteristics.

  16. Temporal dynamics influenced by global change: bee community phenology in urban, agricultural, and natural landscapes.

    Science.gov (United States)

    Leong, Misha; Ponisio, Lauren C; Kremen, Claire; Thorp, Robbin W; Roderick, George K

    2016-03-01

    Urbanization and agricultural intensification of landscapes are important drivers of global change, which in turn have direct impacts on local ecological communities leading to shifts in species distributions and interactions. Here, we illustrate how human-altered landscapes, with novel ornamental and crop plant communities, result not only in changes to local community diversity of floral-dependent species, but also in shifts in seasonal abundance of bee pollinators. Three years of data on the spatio-temporal distributions of 91 bee species show that seasonal patterns of abundance and species richness in human-altered landscapes varied significantly less compared to natural habitats in which floral resources are relatively scarce in the dry summer months. These findings demonstrate that anthropogenic environmental changes in urban and agricultural systems, here mediated through changes in plant resources and water inputs, can alter the temporal dynamics of pollinators that depend on them. Changes in phenology of interactions can be an important, though frequently overlooked, mechanism of global change. © 2015 John Wiley & Sons Ltd.

  17. Subliminal semantic priming changes the dynamic causal influence between the left frontal and temporal cortex.

    Science.gov (United States)

    Matsumoto, Atsushi; Kakigi, Ryusuke

    2014-01-01

    Recent neuroimaging experiments have revealed that subliminal priming of a target stimulus leads to the reduction of neural activity in specific regions concerned with processing the target. Such findings lead to questions about the degree to which the subliminal priming effect is based only on decreased activity in specific local brain regions, as opposed to the influence of neural mechanisms that regulate communication between brain regions. To address this question, this study recorded EEG during performance of a subliminal semantic priming task. We adopted an information-based approach that used independent component analysis and multivariate autoregressive modeling. Results indicated that subliminal semantic priming caused significant modulation of alpha band activity in the left inferior frontal cortex and modulation of gamma band activity in the left inferior temporal regions. The multivariate autoregressive approach confirmed significant increases in information flow from the inferior frontal cortex to inferior temporal regions in the early time window that was induced by subliminal priming. In the later time window, significant enhancement of bidirectional causal flow between these two regions underlying subliminal priming was observed. Results suggest that unconscious processing of words influences not only local activity of individual brain regions but also the dynamics of neural communication between those regions.

  18. Spatio-temporal dynamics of action-effect associations in oculomotor control.

    Science.gov (United States)

    Riechelmann, Eva; Pieczykolan, Aleksandra; Horstmann, Gernot; Herwig, Arvid; Huestegge, Lynn

    2017-10-01

    While there is ample evidence that actions are guided by anticipating their effects (ideomotor control) in the manual domain, much less is known about the underlying characteristics and dynamics of effect-based oculomotor control. Here, we address three open issues. 1) Is action-effect anticipation in oculomotor control reflected in corresponding spatial saccade characteristics in inanimate environments? 2) Does the previously reported dependency of action latency on the temporal effect delay (action-effect interval) also occur in the oculomotor domain? 3) Which temporal effect delay is optimally suited to develop strong action-effect associations over time in the oculomotor domain? Participants executed left or right free-choice saccades to peripheral traffic lights, causing an (immediate or delayed) action-contingent light switch in the upper vs. lower part of the traffic light. Results indicated that saccades were spatially shifted toward the location of the upcoming change, indicating anticipation of the effect (location). Saccade latency was affected by effect delay, suggesting that corresponding time information is integrated into event representations. Finally, delayed (vs. immediate) effects were more effective in strengthening action-effect associations over the course of the experiment, likely due to greater saliency of perceptual changes occurring during target fixation as opposed to changes during saccades (saccadic suppression). Overall, basic principles underlying ideomotor control appear to generalize to the oculomotor domain. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. Fish and phytoplankton exhibit contrasting temporal species abundance patterns in a dynamic north temperate lake.

    Directory of Open Access Journals (Sweden)

    Gretchen J A Hansen

    Full Text Available Temporal patterns of species abundance, although less well-studied than spatial patterns, provide valuable insight to the processes governing community assembly. We compared temporal abundance distributions of two communities, phytoplankton and fish, in a north temperate lake. We used both 17 years of observed relative abundance data as well as resampled data from Monte Carlo simulations to account for the possible effects of non-detection of rare species. Similar to what has been found in other communities, phytoplankton and fish species that appeared more frequently were generally more abundant than rare species. However, neither community exhibited two distinct groups of "core" (common occurrence and high abundance and "occasional" (rare occurrence and low abundance species. Both observed and resampled data show that the phytoplankton community was dominated by occasional species appearing in only one year that exhibited large variation in their abundances, while the fish community was dominated by core species occurring in all 17 years at high abundances. We hypothesize that the life-history traits that enable phytoplankton to persist in highly dynamic environments may result in communities dominated by occasional species capable of reaching high abundances when conditions allow. Conversely, longer turnover times and broad environmental tolerances of fish may result in communities dominated by core species structured primarily by competitive interactions.

  20. Dynamics of Disagreement: Large-Scale Temporal Network Analysis Reveals Negative Interactions in Online Collaboration

    Science.gov (United States)

    Tsvetkova, Milena; García-Gavilanes, Ruth; Yasseri, Taha

    2016-11-01

    Disagreement and conflict are a fact of social life. However, negative interactions are rarely explicitly declared and recorded and this makes them hard for scientists to study. In an attempt to understand the structural and temporal features of negative interactions in the community, we use complex network methods to analyze patterns in the timing and configuration of reverts of article edits to Wikipedia. We investigate how often and how fast pairs of reverts occur compared to a null model in order to control for patterns that are natural to the content production or are due to the internal rules of Wikipedia. Our results suggest that Wikipedia editors systematically revert the same person, revert back their reverter, and come to defend a reverted editor. We further relate these interactions to the status of the involved editors. Even though the individual reverts might not necessarily be negative social interactions, our analysis points to the existence of certain patterns of negative social dynamics within the community of editors. Some of these patterns have not been previously explored and carry implications for the knowledge collection practice conducted on Wikipedia. Our method can be applied to other large-scale temporal collaboration networks to identify the existence of negative social interactions and other social processes.

  1. Fish and Phytoplankton Exhibit Contrasting Temporal Species Abundance Patterns in a Dynamic North Temperate Lake

    Science.gov (United States)

    Hansen, Gretchen J. A.; Carey, Cayelan C.

    2015-01-01

    Temporal patterns of species abundance, although less well-studied than spatial patterns, provide valuable insight to the processes governing community assembly. We compared temporal abundance distributions of two communities, phytoplankton and fish, in a north temperate lake. We used both 17 years of observed relative abundance data as well as resampled data from Monte Carlo simulations to account for the possible effects of non-detection of rare species. Similar to what has been found in other communities, phytoplankton and fish species that appeared more frequently were generally more abundant than rare species. However, neither community exhibited two distinct groups of “core” (common occurrence and high abundance) and “occasional” (rare occurrence and low abundance) species. Both observed and resampled data show that the phytoplankton community was dominated by occasional species appearing in only one year that exhibited large variation in their abundances, while the fish community was dominated by core species occurring in all 17 years at high abundances. We hypothesize that the life-history traits that enable phytoplankton to persist in highly dynamic environments may result in communities dominated by occasional species capable of reaching high abundances when conditions allow. Conversely, longer turnover times and broad environmental tolerances of fish may result in communities dominated by core species structured primarily by competitive interactions. PMID:25651399

  2. Temporal dynamics of genetic variability in a mountain goat (Oreamnos americanus) population.

    Science.gov (United States)

    Ortego, Joaquín; Yannic, Glenn; Shafer, Aaron B A; Mainguy, Julien; Festa-Bianchet, Marco; Coltman, David W; Côté, Steeve D

    2011-04-01

    The association between population dynamics and genetic variability is of fundamental importance for both evolutionary and conservation biology. We combined long-term population monitoring and molecular genetic data from 123 offspring and their parents at 28 microsatellite loci to investigate changes in genetic diversity over 14 cohorts in a small and relatively isolated population of mountain goats (Oreamnos americanus) during a period of demographic increase. Offspring heterozygosity decreased while parental genetic similarity and inbreeding coefficients (F(IS) ) increased over the study period (1995-2008). Immigrants introduced three novel alleles into the population and matings between residents and immigrants produced more heterozygous offspring than local crosses, suggesting that immigration can increase population genetic variability. The population experienced genetic drift over the study period, reflected by a reduced allelic richness over time and an 'isolation-by-time' pattern of genetic structure. The temporal decline of individual genetic diversity despite increasing population size probably resulted from a combination of genetic drift due to small effective population size, inbreeding and insufficient counterbalancing by immigration. This study highlights the importance of long-term genetic monitoring to understand how demographic processes influence temporal changes of genetic diversity in long-lived organisms. © 2011 Blackwell Publishing Ltd.

  3. Right mesial temporal lobe epilepsy impairs empathy-related brain responses to dynamic fearful faces.

    Science.gov (United States)

    Toller, Gianina; Adhimoolam, Babu; Grunwald, Thomas; Huppertz, Hans-Jürgen; Kurthen, Martin; Rankin, Katherine P; Jokeit, Hennric

    2015-03-01

    Unilateral mesial temporal lobe epilepsy (MTLE) has been associated with reduced amygdala responsiveness to fearful faces. However, the effect of unilateral MTLE on empathy-related brain responses in extra-amygdalar regions has not been investigated. Using functional magnetic resonance imaging, we measured empathy-related brain responses to dynamic fearful faces in 34 patients with unilateral MTLE (18 right sided), in an epilepsy (extra-MTLE; n = 16) and in a healthy control group (n = 30). The primary finding was that right MTLE (RMTLE) was associated with decreased activity predominantly in the right amygdala and also in bilateral periaqueductal gray (PAG) but normal activity in the right anterior insula. The results of the extra-MTLE group demonstrate that these reduced amygdala and PAG responses go beyond the attenuation caused by antiepileptic and antidepressant medication. These findings clearly indicate that RMTLE affects the function of mesial temporal and midbrain structures that mediate basic interoceptive input necessary for the emotional awareness of empathic experiences of fear. Together with the decreased empathic concern found in the RMTLE group, this study provides neurobehavioral evidence that patients with RMTLE are at increased risk for reduced empathy towards others' internal states and sheds new light on the nature of social-cognitive impairments frequently accompanying MTLE.

  4. Temporal and Spatial Dynamics of Sediment Anaerobic Ammonium Oxidation (Anammox) Bacteria in Freshwater Lakes.

    Science.gov (United States)

    Yang, Yuyin; Dai, Yu; Li, Ningning; Li, Bingxin; Xie, Shuguang; Liu, Yong

    2017-02-01

    Anaerobic ammonium-oxidizing (anammox) process can play an important role in freshwater nitrogen cycle. However, the distribution of anammox bacteria in freshwater lake and the associated environmental factors remain essentially unclear. The present study investigated the temporal and spatial dynamics of sediment anammox bacterial populations in eutrotrophic Dianchi Lake and mesotrophic Erhai Lake on the Yunnan Plateau (southwestern China). The remarkable spatial change of anammox bacterial abundance was found in Dianchi Lake, while the relatively slight spatial shift occurred in Erhai Lake. Dianchi Lake had greater anammox bacterial abundance than Erhai Lake. In both Dianchi Lake and Erhai Lake, anammox bacteria were much more abundant in summer than in spring. Anammox bacterial community richness, diversity, and structure in these two freshwater lakes were subjected to temporal and spatial variations. Sediment anammox bacterial communities in Dianchi Lake and Erhai Lake were dominated by Candidatus Brocadia and a novel phylotype followed by Candidatus Kuenenia; however, these two lakes had distinct anammox bacterial community structure. In addition, trophic status determined sediment anammox bacterial community structure.

  5. Temporal variability in phosphorus transfers: classifying concentration-discharge event dynamics

    Science.gov (United States)

    Haygarth, P.; Turner, B. L.; Fraser, A.; Jarvis, S.; Harrod, T.; Nash, D.; Halliwell, D.; Page, T.; Beven, K.

    The importance of temporal variability in relationships between phosphorus (P) concentration (Cp) and discharge (Q) is linked to a simple means of classifying the circumstances of Cp-Q relationships in terms of functional types of response. New experimental data at the upstream interface of grassland soil and catchment systems at a range of scales (lysimeters to headwaters) in England and Australia are used to demonstrate the potential of such an approach. Three types of event are defined as Types 1-3, depending on whether the relative change in Q exceeds the relative change in Cp (Type 1), whether Cp and Q are positively inter-related (Type 2) and whether Cp varies yet Q is unchanged (Type 3). The classification helps to characterise circumstances that can be explained mechanistically in relation to (i) the scale of the study (with a tendency towards Type 1 in small scale lysimeters), (ii) the form of P with a tendency for Type 1 for soluble (i.e., <0.45 μm P forms) and (iii) the sources of P with Type 3 dominant where P availability overrides transport controls. This simple framework provides a basis for development of a more complex and quantitative classification of Cp-Q relationships that can be developed further to contribute to future models of P transfer and delivery from slope to stream. Studies that evaluate the temporal dynamics of the transfer of P are currently grossly under-represented in comparison with models based on static/spatial factors.

  6. A customized light sheet microscope to measure spatio-temporal protein dynamics in small model organisms.

    Directory of Open Access Journals (Sweden)

    Matthias Rieckher

    Full Text Available We describe a customizable and cost-effective light sheet microscopy (LSM platform for rapid three-dimensional imaging of protein dynamics in small model organisms. The system is designed for high acquisition speeds and enables extended time-lapse in vivo experiments when using fluorescently labeled specimens. We demonstrate the capability of the setup to monitor gene expression and protein localization during ageing and upon starvation stress in longitudinal studies in individual or small groups of adult Caenorhabditis elegans nematodes. The system is equipped to readily perform fluorescence recovery after photobleaching (FRAP, which allows monitoring protein recovery and distribution under low photobleaching conditions. Our imaging platform is designed to easily switch between light sheet microscopy and optical projection tomography (OPT modalities. The setup permits monitoring of spatio-temporal expression and localization of ageing biomarkers of subcellular size and can be conveniently adapted to image a wide range of small model organisms and tissue samples.

  7. Spatial and temporal dynamics of dengue fever in Peru: 1994-2006.

    Science.gov (United States)

    Chowell, G; Torre, C A; Munayco-Escate, C; Suárez-Ognio, L; López-Cruz, R; Hyman, J M; Castillo-Chavez, C

    2008-12-01

    SUMMARYThe weekly number of dengue cases in Peru, South America, stratified by province for the period 1994-2006 were analysed in conjunction with associated demographic, geographic and climatological data. Estimates of the reproduction number, moderately correlated with population size (Spearman rho=0.28, P=0.03), had a median of 1.76 (IQR 0.83-4.46). The distributions of dengue attack rates and epidemic durations follow power-law (Pareto) distributions (coefficient of determination >85%, Pjungle areas. Our findings suggest a hierarchy of transmission events during the large 2000-2001 epidemic from large to small population areas when serotypes DEN-3 and DEN-4 were first identified (Spearman rho=-0.43, P=0.03). The need for spatial and temporal dengue epidemic data with a high degree of resolution not only increases our understanding of the dynamics of dengue but will also generate new hypotheses and provide a platform for testing innovative control policies.

  8. The surface chemistry determines the spatio-temporal interaction dynamics of quantum dots in atherosclerotic lesions.

    Science.gov (United States)

    Uhl, Bernd; Hirn, Stephanie; Mildner, Karina; Coletti, Raffaele; Massberg, Steffen; Reichel, Christoph A; Rehberg, Markus; Zeuschner, Dagmar; Krombach, Fritz

    2018-03-01

    To optimize the design of nanoparticles for diagnosis or therapy of vascular diseases, it is mandatory to characterize the determinants of nano-bio interactions in vascular lesions. Using ex vivo and in vivo microscopy, we analyzed the interactive behavior of quantum dots with different surface functionalizations in atherosclerotic lesions of ApoE-deficient mice. We demonstrate that quantum dots with different surface functionalizations exhibit specific interactive behaviors with distinct molecular and cellular components of the injured vessel wall. Moreover, we show a role for fibrinogen in the regulation of the spatio-temporal interaction dynamics in atherosclerotic lesions. Our findings emphasize the relevance of surface chemistry-driven nano-bio interactions on the differential in vivo behavior of nanoparticles in diseased tissue.

  9. Quantitative tradeoffs between spatial, temporal, and thermometric resolution of nonresonant Raman thermometry for dynamic experiments.

    Science.gov (United States)

    McGrane, Shawn D; Moore, David S; Goodwin, Peter M; Dattelbaum, Dana M

    2014-01-01

    The ratio of Stokes to anti-Stokes nonresonant spontaneous Raman can provide an in situ thermometer that is noncontact, independent of any material specific parameters or calibrations, can be multiplexed spatially with line imaging, and can be time resolved for dynamic measurements. However, spontaneous Raman cross sections are very small, and thermometric measurements are often limited by the amount of laser energy that can be applied without damaging the sample or changing its temperature appreciably. In this paper, we quantitatively detail the tradeoff space between spatial, temporal, and thermometric accuracy measurable with spontaneous Raman. Theoretical estimates are pinned to experimental measurements to form realistic expectations of the resolution tradeoffs appropriate to various experiments. We consider the effects of signal to noise, collection efficiency, laser heating, pulsed laser ablation, and blackbody emission as limiting factors, provide formulae to help choose optimal conditions and provide estimates relevant to planning experiments along with concrete examples for single-shot measurements.

  10. Temporal dynamics of the response to Al stress in Eucalyptus grandis × Eucalyptus camaldulensis

    Directory of Open Access Journals (Sweden)

    Berenice K. de Alcântara

    2015-06-01

    Full Text Available Lipid peroxidation and root elongation of Eucalyptus grandis × Eucalyptus camaldulensis were studied under stress conditions in response to aluminum (Al, a metal known to limit agricultural productivity in acidic soils primarily due to reduced root elongation. In Brazil, the Grancam 1277 hybrid (E. grandis × E. camaldulensis has been planted in the "Cerrado", a region of the country with a wide occurrence of acidic soils. The present study demonstrated that the hybrid exhibited root growth reduction and increased levels of lipid peroxidation after 24h of treatment with 100 µM of Al, which was followed by a reduction in lipid peroxidation levels and the recovery of root elongation after 48h of Al exposure, suggesting a rapid response to the early stressful conditions induced by Al. The understanding of the temporal dynamics of Al tolerance may be useful for selecting more tolerant genotypes and for identifying genes of interest for applications in bioengineering.

  11. Spatio-temporal dynamics of the white-eye square superlattice pattern in dielectric barrier discharge

    International Nuclear Information System (INIS)

    Wei, Lingyan; Dong, Lifang; Feng, Jianyu; Liu, Weibo; Fan, Weili; Pan, Yuyang

    2016-01-01

    We report on the first investigation of the white-eye square superlattice pattern (WESSP) in a dielectric barrier discharge system. The evolution of patterns with increasing voltage is given. A phase diagram of WESSP as functions of gas pressure p and argon concentration φ is presented. The spatio-temporal dynamics of the WESSP is studied by using an intensified charge-coupled device camera and photomultipliers. Results show that the WESSP consists of four different transient sublattices, whose discharge sequence is small spots—spots on the line—halos—central spots in each half voltage cycle. The discharge moment and position of each sublattice are dependent upon the field of the wall charges produced by all sublattices discharged previously. (paper)

  12. Comparing the temporal dynamics of thematic and taxonomic processing using event-related potentials.

    Directory of Open Access Journals (Sweden)

    Olivera Savic

    Full Text Available We report the results of a study comparing the temporal dynamics of thematic and taxonomic knowledge activation in a picture-word priming paradigm using event-related potentials. Although we found no behavioral differences between thematic and taxonomic processing, ERP data revealed distinct patterns of N400 and P600 amplitude modulation for thematic and taxonomic priming. Thematically related target stimuli elicited less negativity than taxonomic targets between 280-460 ms after stimulus onset, suggesting easier semantic processing of thematic than taxonomic relationships. Moreover, P600 mean amplitude was significantly increased for taxonomic targets between 520-600 ms, consistent with a greater need for stimulus reevaluation in that condition. These results offer novel evidence in favor of a dissociation between thematic and taxonomic thinking in the early phases of conceptual evaluation.

  13. Comparing the temporal dynamics of thematic and taxonomic processing using event-related potentials.

    Science.gov (United States)

    Savic, Olivera; Savic, Andrej M; Kovic, Vanja

    2017-01-01

    We report the results of a study comparing the temporal dynamics of thematic and taxonomic knowledge activation in a picture-word priming paradigm using event-related potentials. Although we found no behavioral differences between thematic and taxonomic processing, ERP data revealed distinct patterns of N400 and P600 amplitude modulation for thematic and taxonomic priming. Thematically related target stimuli elicited less negativity than taxonomic targets between 280-460 ms after stimulus onset, suggesting easier semantic processing of thematic than taxonomic relationships. Moreover, P600 mean amplitude was significantly increased for taxonomic targets between 520-600 ms, consistent with a greater need for stimulus reevaluation in that condition. These results offer novel evidence in favor of a dissociation between thematic and taxonomic thinking in the early phases of conceptual evaluation.

  14. Self-Organization of Spatio-Temporal Hierarchy via Learning of Dynamic Visual Image Patterns on Action Sequences.

    Science.gov (United States)

    Jung, Minju; Hwang, Jungsik; Tani, Jun

    2015-01-01

    It is well known that the visual cortex efficiently processes high-dimensional spatial information by using a hierarchical structure. Recently, computational models that were inspired by the spatial hierarchy of the visual cortex have shown remarkable performance in image recognition. Up to now, however, most biological and computational modeling studies have mainly focused on the spatial domain and do not discuss temporal domain processing of the visual cortex. Several studies on the visual cortex and other brain areas associated with motor control support that the brain also uses its hierarchical structure as a processing mechanism for temporal information. Based on the success of previous computational models using spatial hierarchy and temporal hierarchy observed in the brain, the current report introduces a novel neural network model for the recognition of dynamic visual image patterns based solely on the learning of exemplars. This model is characterized by the application of both spatial and temporal constraints on local neural activities, resulting in the self-organization of a spatio-temporal hierarchy necessary for the recognition of complex dynamic visual image patterns. The evaluation with the Weizmann dataset in recognition of a set of prototypical human movement patterns showed that the proposed model is significantly robust in recognizing dynamically occluded visual patterns compared to other baseline models. Furthermore, an evaluation test for the recognition of concatenated sequences of those prototypical movement patterns indicated that the model is endowed with a remarkable capability for the contextual recognition of long-range dynamic visual image patterns.

  15. Modelling temporal and spatial dynamics of benthic fauna in North-West-European shelf seas

    Science.gov (United States)

    Lessin, Gennadi; Bruggeman, Jorn; Artioli, Yuri; Butenschön, Momme; Blackford, Jerry

    2017-04-01

    Benthic zones of shallow shelf seas receive high amounts of organic material. Physical processes such as resuspension, as well as complex transformations mediated by diverse faunal and microbial communities, define fate of this material, which can be returned to the water column, reworked within sediments or ultimately buried. In recent years, numerical models of various complexity and serving different goals have been developed and applied in order to better understand and predict dynamics of benthic processes. ERSEM includes explicit parameterisations of several groups of benthic biota, which makes it particularly applicable for studies of benthic biodiversity, biological interactions within sediments and benthic-pelagic coupling. To assess model skill in reproducing temporal (inter-annual and seasonal) dynamics of major benthic macrofaunal groups, 1D model simulation results were compared with data from the Western Channel Observatory (WCO) benthic survey. The benthic model was forced with organic matter deposition rates inferred from observed phytoplankton abundance and model parameters were subsequently recalibrated. Based on model results and WCO data comparison, deposit-feeders exert clear seasonal variability, while for suspension-feeders inter-annual variability is more pronounced. Spatial distribution of benthic fauna was investigated using results of a full-scale NEMO-ERSEM hindcast simulation of the North-West European Shelf Seas area, covering the period of 1981-2014. Results suggest close relationship between spatial distribution of biomass of benthic faunal functional groups in relation to bathymetry, hydrodynamic conditions and organic matter supply. Our work highlights that it is feasible to construct, implement and validate models that explicitly include functional groups of benthic macrofauna. Moreover, the modelling approach delivers detailed information on benthic biogeochemistry and food-web at spatial and temporal scales that are unavailable

  16. Temporal dynamics of abundance and composition of nitrogen-fixing communities across agricultural soils.

    Directory of Open Access Journals (Sweden)

    Michele C Pereira E Silva

    Full Text Available BACKGROUND: Despite the fact that the fixation of nitrogen is one of the most significant nutrient processes in the terrestrial ecosystem, a thorough study of the spatial and temporal patterns in the abundance and distribution of N-fixing communities has been missing so far. METHODOLOGY/PRINCIPAL FINDINGS: In order to understand the dynamics of diazotrophic communities and their resilience to external changes, we quantified the abundance and characterized the bacterial community structures based on the nifH gene, using real-time PCR, PCR-DGGE and 454-pyrosequencing, across four representative Dutch soils during one growing season. In general, higher nifH gene copy numbers were observed in soils with higher pH than in those with lower pH, but lower numbers were related to increased nitrate and ammonium levels. Results from nifH gene pyrosequencing confirmed the observed PCR-DGGE patterns, which indicated that the N fixers are highly dynamic across time, shifting around 60%. Forward selection on CCA analysis identified N availability as the main driver of these variations, as well as of the evenness of the communities, leading to very unequal communities. Moreover, deep sequencing of the nifH gene revealed that sandy soils (B and D had the lowest percentage of shared OTUs across time, compared with clayey soils (G and K, indicating the presence of a community under constant change. Cosmopolitan nifH species (present throughout the season were affiliated with Bradyrhizobium, Azospirillum and Methylocistis, whereas other species increased their abundances progressively over time, when appropriate conditions were met, as was notably the case for Paenibacilus and Burkholderia. CONCLUSIONS: Our study provides the first in-depth pyrosequencing analysis of the N-fixing community at both spatial and temporal scales, providing insights into the cosmopolitan and specific portions of the nitrogen fixing bacterial communities in soil.

  17. Retinal Vascular and Oxygen Temporal Dynamic Responses to Light Flicker in Humans.

    Science.gov (United States)

    Felder, Anthony E; Wanek, Justin; Blair, Norman P; Shahidi, Mahnaz

    2017-11-01

    To mathematically model the temporal dynamic responses of retinal vessel diameter (D), oxygen saturation (SO2), and inner retinal oxygen extraction fraction (OEF) to light flicker and to describe their responses to its cessation in humans. In 16 healthy subjects (age: 60 ± 12 years), retinal oximetry was performed before, during, and after light flicker stimulation. At each time point, five metrics were measured: retinal arterial and venous D (DA, DV) and SO2 (SO2A, SO2V), and OEF. Intra- and intersubject variability of metrics was assessed by coefficient of variation of measurements before flicker within and among subjects, respectively. Metrics during flicker were modeled by exponential functions to determine the flicker-induced steady state metric values and the time constants of changes. Metrics after the cessation of flicker were compared to those before flicker. Intra- and intersubject variability for all metrics were less than 6% and 16%, respectively. At the flicker-induced steady state, DA and DV increased by 5%, SO2V increased by 7%, and OEF decreased by 13%. The time constants of DA and DV (14, 15 seconds) were twofold smaller than those of SO2V and OEF (39, 34 seconds). Within 26 seconds after the cessation of flicker, all metrics were not significantly different from before flicker values (P ≥ 0.07). Mathematical modeling revealed considerable differences in the time courses of changes among metrics during flicker, indicating flicker duration should be considered separately for each metric. Future application of this method may be useful to elucidate alterations in temporal dynamic responses to light flicker due to retinal diseases.

  18. Child Temperamental Flexibility Moderates the Relation between Positive Parenting and Adolescent Adjustment

    Science.gov (United States)

    Rabinowitz, Jill A.; Drabick, Deborah A.G.; Reynolds, Maureen D.; Clark, Duncan B.; Olino, Thomas M.

    2016-01-01

    Temperamental flexibility and lower positive parenting are associated with internalizing and externalizing problems; however, youth varying in flexibility may be differentially affected by positive parenting in the prediction of symptoms. We examined whether children's flexibility moderated prospective relations between maternal and paternal positive parenting and youth internalizing and externalizing symptoms during adolescence. Participants (N =775, 71% male) and their caregivers completed measures when youth were 10-12 and 12-14 years old. Father positive parenting interacted with child flexibility to predict father-reported internalizing and externalizing problems. Consistent with the diathesis-stress model, children lower in flexibility experienced greater symptoms than children higher in flexibility in lower positive parenting contexts. Among children lower in flexibility, lower paternal positive parenting was associated with greater internalizing and externalizing symptoms compared to higher paternal positive parenting. However, among youth higher in flexibility, symptom levels were similar regardless of whether youth experienced lower or higher paternal positive parenting. PMID:26834305

  19. Effects of prenatal and postnatal maternal emotional stress on toddlers' cognitive and temperamental development.

    Science.gov (United States)

    Lin, Yanfen; Xu, Jian; Huang, Jun; Jia, Yinan; Zhang, Jinsong; Yan, Chonghuai; Zhang, Jun

    2017-01-01

    Maternal stress is associated with impairments in the neurodevelopment of offspring; however, the effects of the timing of exposure to maternal stress on a child's neurodevelopment are unclear. In 2010, we studied 225 mother-child pairs in Shanghai, recruiting mothers in mid-to-late pregnancy and monitoring offspring from birth until 30 months of age. Maternal stress was assessed prenatally (at 28-36 weeks of gestation) and postnatally (at 24-30 months postpartum) using the Symptom-Checklist-90-Revised Scale (SCL-90-R) and Life-Event-Stress Scale to evaluate mothers' emotional stress and life event stress levels, respectively. Children's cognition and temperament were assessed at 24-30 months of age using the Gesell Development Scale and Toddler Temperament Scale, respectively. Multi-variable linear regression models were used to associate prenatal and postnatal stress with child cognitive and temperamental development. Maternal prenatal and postnatal Global Severity Index (GSI) of SCL-90-R were moderately correlated (ICC r=0.30, Ptoddlers' gross motor, fine motor, adaptive and social behavior development independently of postnatal GSI, while the increase in postnatal GSI was associated with changes in multiple temperament dimensions independently of prenatal GSI. The effects of prenatal and postnatal depression scores of SCL-90-R were similar to those of GSI. Relatively small sample size. Compared with postnatal exposure, children's cognitive development may be more susceptible to prenatal exposure to maternal emotional stress, whereas temperamental development may be more affected by postnatal exposure to maternal emotional stress compared with prenatal exposure. Copyright © 2016 Elsevier B.V. All rights reserved.

  20. Temporal contrast enhancement and parametric imaging for the visualisation of time patterns in dynamic scintigraphic imaging

    International Nuclear Information System (INIS)

    Deconinck, F.; Bossuyt, A.; Lepoudre, R.

    1982-01-01

    Image contrast, photon noise and sampling frequency limit the visual extraction of relevant temporal information in scintigraphic image series. When the Unitation is mainly due to low temporal contrast, temporal contrast enhancement will strongly improve the perceptibility of time patterns in the series. When the limitation is due to photon noise and limited temporal sampling, parametric imaging by means of the Hadamard transform can visualise temporal patterns. (WU)

  1. Bioluminescence in a complex coastal environment: 1. Temporal dynamics of nighttime water-leaving radiance

    Science.gov (United States)

    Moline, Mark A.; Oliver, Matthew J.; Mobley, Curtis D.; Sundman, Lydia; Bensky, Thomas; Bergmann, Trisha; Bissett, W. Paul; Case, James; Raymond, Erika H.; Schofield, Oscar M. E.

    2007-11-01

    Nighttime water-leaving radiance is a function of the depth-dependent distribution of both the in situ bioluminescence emissions and the absorption and scattering properties of the water. The vertical distributions of these parameters were used as inputs for a modified one-dimensional radiative transfer model to solve for spectral bioluminescence water-leaving radiance from prescribed depths of the water column. Variation in the water-leaving radiance was consistent with local episodic physical forcing events, with tidal forcing, terrestrial runoff, particulate accumulation, and biological responses influencing the shorter timescale dynamics. There was a >90 nm shift in the peak water-leaving radiance from blue (˜474 nm) to green as light propagated to the surface. In addition to clues in ecosystem responses to physical forcing, the temporal dynamics in intensity and spectral quality of water-leaving radiance provide suitable ranges for assessing detection. This may provide the information needed to estimate the depth of internal light sources in the ocean, which is discussed in part 2 of this paper.

  2. Spatial and temporal dynamics of corticosterone and corticosterone binding globulin are driven by environmental heterogeneity.

    Science.gov (United States)

    Shultz, Michael Todd; Kitaysky, Alexander Stanislav

    2008-02-01

    The question of whether changes in glucocorticoid concentrations reflect consistent changes in physiology associated with transitions between different stages of reproduction, or whether they reflect responses to environmental conditions, is one the central issues in field endocrinology studies. We examined the temporal and spatial dynamics of corticosterone (CORT, baseline, and acute stress-induced) and corticosterone binding globulin (CBG) concentrations in blood of Black-legged Kittiwakes (Rissa tridactyla) breeding at four major colonies in the Bering Sea, Alaska, during 1999-2005. We found that total CORT, free CORT, and CBG capacity varied inconsistently among reproductive stages, colonies, and years. Total CORT levels were positively correlated with CBG capacity. Variation in free CORT was largely driven by variation in total CORT. Results suggest that the adrenocortical function and CBG in breeding kittiwakes do not vary as a consequence of stage-specific modulation associated with a particular reproductive stage as in some short-lived passerine birds. Rather, in accord with predictions for a long-lived species, the lack of consistent colony, year, and reproductive stage patterns in baseline and maximum CORT, and CBG indicates that environmental factors, probably local dynamics of food availability, drive variation in these factors.

  3. Dynamic computed tomography based on spatio-temporal analysis in acute stroke: Preliminary study

    Energy Technology Data Exchange (ETDEWEB)

    Park, Ha Young; Pyeon, Do Yeong; Kim, Da Hye; Jung, Young Jin [Dongseo University, Busan (Korea, Republic of)

    2016-12-15

    Acute stroke is a one of common disease that require fast diagnosis and treatment to save patients life. however, the acute stroke may cause lifelong disability due to brain damage with no prompt surgical procedure. In order to diagnose the Stroke, brain perfusion CT examination and possible rapid implementation of 3D angiography has been widely used. However, a low-dose technique should be applied for the examination since a lot of radiation exposure to the patient may cause secondary damage for the patients. Therefore, the degradation of the measured CT images may interferes with a clinical check in that blood vessel shapes o n the CT image are significantly affected by gaussian noise. In this study, we employed the spatio-temporal technique to analyze dynamic (brain perfusion) CT data to improve an image quality for successful clinical diagnosis. As a results, proposed technique could remove gaussian noise successfully, demonstrated a possibility of new image segmentation technique for CT angiography. Qualitative evaluation was conducted by skilled radiological technologists, indicated significant quality improvement of dynamic CT images. the proposed technique will be useful tools as a clinical application for brain perfusion CT examination.

  4. Measuring and modeling the temporal dynamics of nitrogen balance in an experimental-scale paddy field

    Science.gov (United States)

    Tseng, C.; Lin, Y.

    2013-12-01

    Nitrogen balance involves many mechanisms and plays an important role to maintain the function of nature. Fertilizer application in agriculture activity is usually seen as a common and significant nitrogen input to environment. Improper fertilizer application on paddy field can result in great amount of various types of nitrogen losses. Hence, it is essential to understand and quantify the nitrogen dynamics in paddy field for fertilizer management and pollution control. In this study, we develop a model which considers major transformation processes of nitrogen (e.g. volatilization, nitrification, denitrification and plant uptake). In addition, we measured different types of nitrogen in plants, soil and water at plant growth stages in an experimental-scale paddy field in Taiwan. The measurement includes total nitrogen in plants and soil, and ammonium-N (NH4+-N), nitrate-N (NO3--N) and organic nitrogen in water. The measured data were used to calibrate the model parameters and validate the model for nitrogen balance simulation. The results showed that the model can accurately estimate the temporal dynamics of nitrogen balance in paddy field during the whole growth stage. This model might be helpful and useful for future fertilizer management and pollution control in paddy field.

  5. The Temporal Dynamics of Coastal Phytoplankton and Bacterioplankton in the Eastern Mediterranean Sea.

    Directory of Open Access Journals (Sweden)

    Ofrat Raveh

    Full Text Available This study considers variability in phytoplankton and heterotrophic bacterial abundances and production rates, in one of the most oligotrophic marine regions in the world-the Levantine Basin. The temporal dynamics of these planktonic groups were studied in the coastal waters of the southeastern Mediterranean Sea approximately every two weeks for a total of two years. Heterotrophic bacteria were abundant mostly during late summer and midwinter, and were positively correlated with bacterial production and with N2 fixation. Based on size fractionating, picophytoplankton was abundant during the summer, whereas nano-microphytoplankton predominated during the winter and early spring, which were also evident in the size-fractionated primary production rates. Autotrophic abundance and production correlated negatively with temperature, but did not correlate with inorganic nutrients. Furthermore, a comparison of our results with results from the open Levantine Basin demonstrates that autotrophic and heterotrophic production, as well as N2 fixation rates, are considerably higher in the coastal habitat than in the open sea, while nutrient levels or cell abundance are not different. These findings have important ecological implications for food web dynamics and for biological carbon sequestration in this understudied region.

  6. Exploring the isotopic niche: isotopic variance, physiological incorporation, and the temporal dynamics of foraging

    Directory of Open Access Journals (Sweden)

    Justin Douglas Yeakel

    2016-01-01

    Full Text Available Consumer foraging behaviors are dynamic, changing in response to prey availability, seasonality, competition, and even the consumer's physiological state. The isotopic composition of a consumer is a product of these factors as well as the isotopic `landscape' of its prey, i.e. the isotopic mixing space. Stable isotope mixing models are used to back-calculate the most likely proportional contribution of a set of prey to a consumer's diet based on their respective isotopic distributions, however they are disconnected from ecological process. Here we build a mechanistic framework that links the ecological and physiological processes of an individual consumer to the isotopic distribution that describes its diet, and ultimately to the isotopic composition of its own tissues, defined as its `isotopic niche’. By coupling these processes, we systematically investigate under what conditions the isotopic niche of a consumer changes as a function of both the geometric properties of its mixing space and foraging strategies that may be static or dynamic over time. Results of our derivations reveal general insight into the conditions impacting isotopic niche width as a function of consumer specialization on prey, as well as the consumer's ability to transition between diets over time. We show analytically that moderate specialization on isotopically unique prey can serve to maximize a consumer's isotopic niche width, while temporally dynamic diets will tend to result in peak isotopic variance during dietary transitions. We demonstrate the relevance of our theoretical findings by examining a marine system composed of nine invertebrate species commonly consumed by sea otters. In general, our analytical framework highlights the complex interplay of mixing space geometry and consumer dietary behavior in driving expansion and contraction of the isotopic niche. Because this approach is established on ecological mechanism, it is well-suited for enhancing the

  7. Temporal and spatial dynamics of phytoplankton near farm fish in eutrophic reservoir in Pernambuco, Brazil

    Directory of Open Access Journals (Sweden)

    Ariadne do Nascimento Moura

    2012-06-01

    Full Text Available Spatial and temporal variations in phytoplankton communities in continental waters have received attention from limnologists, since they are differently influenced by many physico-chemical and biological factors. This study was undertaken with the aim to identify the environmental variables that influence the temporal and spatial dynamics of the phytoplankton near a fish farm in the Jucazinho reservoir, in a semi-arid region of Northeastern Brazil. Samples were taken from three sampling sites, at two depths during the rainy (Aug 2008, Feb and Mar 2009 and dry (Oct, Nov and Dec 2008 seasons. Phytoplankton was identified, density determined, and biomass values obtained. Concomitantly, abiotic analyses were performed for the characterization of the system. The reservoir was homogeneous with regard to the spatial-temporal variation in hydrological variables: water well oxygenated at the surface and anoxic at the bottom; pH ranging from neutral to alkaline; temperatures always above 25ºC; high turbidity; and high electrical conductivity at all sampling sites and both depths. For both seasons, there was limited nitrogen and high concentrations of phosphorus. Cyanophyta species were predominant, generally representing 80% of the phytoplankton biomass throughout practically the entire study, at all sampling sites and both depths. Co-dominance of cyanobacteria belonging to H1, MP, S1 and Sn associations was recorded in most of the months studied, except August 2008, when there was a substitution of the S1 association (Planktothrix agardhii by the P association (Aulacoseira granulata. Water temperature, precipitation and pH were the parameters with the greatest influence over the temporal variation in phytoplankton, whereas the vertical distribution of the phytoplankton biomass was directly related to the availability of light in the wáter column. There were no spatial or temporal differences in water quality, likely due to the fact that the sampling

  8. Physical Exercise Leads to Rapid Adaptations in Hippocampal Vasculature : Temporal Dynamics and Relationship to Cell Proliferation and Neurogenesis

    NARCIS (Netherlands)

    Van der Borght, Karin; Kobor-Nyakas, Dora E.; Klauke, Karin; Eggen, Bart J. L.; Nyakas, Csaba; Van der Zee, Eddy A.; Meerlo, Peter

    2009-01-01

    Increased levels of angiogenesis and neurogenesis possibly mediate the beneficial effects of physical activity on hippocampal plasticity. This study was designed to investigate the temporal dynamics of exercise-induced changes in hippocampal angiogenesis and cell proliferation. Mice were housed with

  9. Temporal Dynamics of Social Exchange and the Development of Solidarity: "Testing the Waters" versus "Taking a Leap of Faith"

    Science.gov (United States)

    Kuwabara, Ko; Sheldon, Oliver

    2012-01-01

    In their concerted efforts to unpack the microprocesses that transform repeated exchanges into an exchange relation, exchange theorists have paid little attention to how actors perceive changes and dynamics in exchanges over time. We help fill this gap by studying how temporal patterns of exchange affect the development of cohesion. Some exchange…

  10. Detecting Temporal Change in Dynamic Sounds: On the Role of Stimulus Duration, Speed, and Emotion

    Directory of Open Access Journals (Sweden)

    Annett eSchirmer

    2016-01-01

    Full Text Available For dynamic sounds, such as vocal expressions, duration often varies alongside speed. Compared to longer sounds, shorter sounds unfold more quickly. Here, we asked whether listeners implicitly use this confound when representing temporal regularities in their environment. In addition, we explored the role of emotions in this process. Using a mismatch negativity (MMN paradigm, we asked participants to watch a silent movie while passively listening to a stream of task-irrelevant sounds. In Experiment 1, one surprised and one neutral vocalization were compressed and stretched to create stimuli of 378 and 600 ms duration. Stimuli were presented in four blocks, two of which used surprised and two of which used neutral expressions. In one surprised and one neutral block, short and long stimuli served as standards and deviants, respectively. In the other two blocks, the assignment of standards and deviants was reversed. We observed a climbing MMN-like negativity shortly after deviant onset, which suggests that listeners implicitly track sound speed and detect speed changes. Additionally, this MMN-like effect emerged earlier and was larger for long than short deviants, suggesting greater sensitivity to duration increments or slowing down than to decrements or speeding up. Last, deviance detection was facilitated in surprised relative to neutral blocks, indicating that emotion enhances temporal processing. Experiment 2 was comparable to Experiment 1 with the exception that sounds were spectrally rotated to remove vocal emotional content. This abolished the emotional processing benefit, but preserved the other effects. Together, these results provide insights into listener sensitivity to sound speed and raise the possibility that speed biases duration judgments implicitly in a feed-forward manner. Moreover, this bias may be amplified for duration increments relative to decrements and within an emotional relative to a neutral stimulus context.

  11. Using the relational event model (REM) to investigate the temporal dynamics of animal social networks.

    Science.gov (United States)

    Tranmer, Mark; Marcum, Christopher Steven; Morton, F Blake; Croft, Darren P; de Kort, Selvino R

    2015-03-01

    Social dynamics are of fundamental importance in animal societies. Studies on nonhuman animal social systems often aggregate social interaction event data into a single network within a particular time frame. Analysis of the resulting network can provide a useful insight into the overall extent of interaction. However, through aggregation, information is lost about the order in which interactions occurred, and hence the sequences of actions over time. Many research hypotheses relate directly to the sequence of actions, such as the recency or rate of action, rather than to their overall volume or presence. Here, we demonstrate how the temporal structure of social interaction sequences can be quantified from disaggregated event data using the relational event model (REM). We first outline the REM, explaining why it is different from other models for longitudinal data, and how it can be used to model sequences of events unfolding in a network. We then discuss a case study on the European jackdaw, Corvus monedula , in which temporal patterns of persistence and reciprocity of action are of interest, and present and discuss the results of a REM analysis of these data. One of the strengths of a REM analysis is its ability to take into account different ways in which data are collected. Having explained how to take into account the way in which the data were collected for the jackdaw study, we briefly discuss the application of the model to other studies. We provide details of how the models may be fitted in the R statistical software environment and outline some recent extensions to the REM framework.

  12. Temporal dynamics of selective attention and conflict resolution during cross-dimensional go-nogo decisions

    Directory of Open Access Journals (Sweden)

    Moschner Carsten

    2007-08-01

    Full Text Available Abstract Background Decision-making is a fundamental capacity which is crucial to many higher-order psychological functions. We recorded event-related potentials (ERPs during a visual target-identification task that required go-nogo choices. Targets were identified on the basis of cross-dimensional conjunctions of particular colors and forms. Color discriminability was manipulated in three conditions to determine the effects of color distinctiveness on component processes of decision-making. Results Target identification was accompanied by the emergence of prefrontal P2a and P3b. Selection negativity (SN revealed that target-compatible features captured attention more than target-incompatible features, suggesting that intra-dimensional attentional capture was goal-contingent. No changes of cross-dimensional selection priorities were measurable when color discriminability was altered. Peak latencies of the color-related SN provided a chronometric measure of the duration of attention-related neural processing. ERPs recorded over the frontocentral scalp (N2c, P3a revealed that color-overlap distractors, more than form-overlap distractors, required additional late selection. The need for additional response selection induced by color-overlap distractors was severely reduced when color discriminability decreased. Conclusion We propose a simple model of cross-dimensional perceptual decision-making. The temporal synchrony of separate color-related and form-related choices determines whether or not distractor processing includes post-perceptual stages. ERP measures contribute to a comprehensive explanation of the temporal dynamics of component processes of perceptual decision-making.

  13. Spatio-temporal patterns of soil erosion and suspended sediment dynamics in the Mekong River Basin.

    Science.gov (United States)

    Suif, Zuliziana; Fleifle, Amr; Yoshimura, Chihiro; Saavedra, Oliver

    2016-10-15

    Understanding of the distribution patterns of sediment erosion, concentration and transport in river basins is critically important as sediment plays a major role in river basin hydrophysical and ecological processes. In this study, we proposed an integrated framework for the assessment of sediment dynamics, including soil erosion (SE), suspended sediment load (SSL) and suspended sediment concentration (SSC), and applied this framework to the Mekong River Basin. The Revised Universal Soil Loss Equation (RUSLE) model was adopted with a geographic information system to assess SE and was coupled with a sediment accumulation and a routing scheme to simulate SSL. This framework also analyzed Landsat imagery captured between 1987 and 2000 together with ground observations to interpolate spatio-temporal patterns of SSC. The simulated SSL results from 1987 to 2000 showed the relative root mean square error of 41% and coefficient of determination (R(2)) of 0.89. The polynomial relationship of the near infrared exoatmospheric reflectance and the band 4 wavelength (760-900nm) to the observed SSC at 9 sites demonstrated the good agreement (overall relative RMSE=5.2%, R(2)=0.87). The result found that the severe SE occurs in the upper (China and Lao PDR) and lower (western part of Vietnam) regions. The SSC in the rainy season (June-November) showed increasing and decreasing trends longitudinally in the upper (China and Lao PDR) and lower regions (Cambodia), respectively, while the longitudinal profile of SSL showed a fluctuating trend along the river in the early rainy season. Overall, the results described the unique spatio-temporal patterns of SE, SSL and SSC in the Mekong River Basin. Thus, the proposed integrated framework is useful for elucidating complex process of sediment generation and transport in the land and river systems of large river basins. Copyright © 2016 Elsevier B.V. All rights reserved.

  14. Temporal Dynamics of Soil Microbial Communities below the Seedbed under Two Contrasting Tillage Regimes

    Directory of Open Access Journals (Sweden)

    Florine Degrune

    2017-06-01

    Full Text Available Agricultural productivity relies on a wide range of ecosystem services provided by the soil biota. Plowing is a fundamental component of conventional farming, but long-term detrimental effects such as soil erosion and loss of soil organic matter have been recognized. Moving towards more sustainable management practices such as reduced tillage or crop residue retention can reduce these detrimental effects, but will also influence structure and function of the soil microbiota with direct consequences for the associated ecosystem services. Although there is increasing evidence that different tillage regimes alter the soil microbiome, we have a limited understanding of the temporal dynamics of these effects. Here, we used high-throughput sequencing of bacterial and fungal ribosomal markers to explore changes in soil microbial community structure under two contrasting tillage regimes (conventional and reduced tillage either with or without crop residue retention. Soil samples were collected over the growing season of two crops (Vicia faba and Triticum aestivum below the seedbed (15–20 cm. Tillage, crop and growing stage were significant determinants of microbial community structure, but the impact of tillage showed only moderate temporal dependency. Whereas the tillage effect on soil bacteria showed some temporal dependency and became less strong at later growing stages, the tillage effect on soil fungi was more consistent over time. Crop residue retention had only a minor influence on the community. Six years after the conversion from conventional to reduced tillage, soil moisture contents and nutrient levels were significantly lower under reduced than under conventional tillage. These changes in edaphic properties were related to specific shifts in microbial community structure. Notably, bacterial groups featuring copiotrophic lifestyles or potentially carrying the ability to degrade more recalcitrant compounds were favored under conventional

  15. Temporal Dynamics of Soil Microbial Communities below the Seedbed under Two Contrasting Tillage Regimes.

    Science.gov (United States)

    Degrune, Florine; Theodorakopoulos, Nicolas; Colinet, Gilles; Hiel, Marie-Pierre; Bodson, Bernard; Taminiau, Bernard; Daube, Georges; Vandenbol, Micheline; Hartmann, Martin

    2017-01-01

    Agricultural productivity relies on a wide range of ecosystem services provided by the soil biota. Plowing is a fundamental component of conventional farming, but long-term detrimental effects such as soil erosion and loss of soil organic matter have been recognized. Moving towards more sustainable management practices such as reduced tillage or crop residue retention can reduce these detrimental effects, but will also influence structure and function of the soil microbiota with direct consequences for the associated ecosystem services. Although there is increasing evidence that different tillage regimes alter the soil microbiome, we have a limited understanding of the temporal dynamics of these effects. Here, we used high-throughput sequencing of bacterial and fungal ribosomal markers to explore changes in soil microbial community structure under two contrasting tillage regimes (conventional and reduced tillage) either with or without crop residue retention. Soil samples were collected over the growing season of two crops ( Vicia faba and Triticum aestivum ) below the seedbed (15-20 cm). Tillage, crop and growing stage were significant determinants of microbial community structure, but the impact of tillage showed only moderate temporal dependency. Whereas the tillage effect on soil bacteria showed some temporal dependency and became less strong at later growing stages, the tillage effect on soil fungi was more consistent over time. Crop residue retention had only a minor influence on the community. Six years after the conversion from conventional to reduced tillage, soil moisture contents and nutrient levels were significantly lower under reduced than under conventional tillage. These changes in edaphic properties were related to specific shifts in microbial community structure. Notably, bacterial groups featuring copiotrophic lifestyles or potentially carrying the ability to degrade more recalcitrant compounds were favored under conventional tillage, whereas

  16. The effect of STDP temporal kernel structure on the learning dynamics of single excitatory and inhibitory synapses.

    Directory of Open Access Journals (Sweden)

    Yotam Luz

    Full Text Available Spike-Timing Dependent Plasticity (STDP is characterized by a wide range of temporal kernels. However, much of the theoretical work has focused on a specific kernel - the "temporally asymmetric Hebbian" learning rules. Previous studies linked excitatory STDP to positive feedback that can account for the emergence of response selectivity. Inhibitory plasticity was associated with negative feedback that can balance the excitatory and inhibitory inputs. Here we study the possible computational role of the temporal structure of the STDP. We represent the STDP as a superposition of two processes: potentiation and depression. This allows us to model a wide range of experimentally observed STDP kernels, from Hebbian to anti-Hebbian, by varying a single parameter. We investigate STDP dynamics of a single excitatory or inhibitory synapse in purely feed-forward architecture. We derive a mean-field-Fokker-Planck dynamics for the synaptic weight and analyze the effect of STDP structure on the fixed points of the mean field dynamics. We find a phase transition along the Hebbian to anti-Hebbian parameter from a phase that is characterized by a unimodal distribution of the synaptic weight, in which the STDP dynamics is governed by negative feedback, to a phase with positive feedback characterized by a bimodal distribution. The critical point of this transition depends on general properties of the STDP dynamics and not on the fine details. Namely, the dynamics is affected by the pre-post correlations only via a single number that quantifies its overlap with the STDP kernel. We find that by manipulating the STDP temporal kernel, negative feedback can be induced in excitatory synapses and positive feedback in inhibitory. Moreover, there is an exact symmetry between inhibitory and excitatory plasticity, i.e., for every STDP rule of inhibitory synapse there exists an STDP rule for excitatory synapse, such that their dynamics is identical.

  17. Temporal networks

    CERN Document Server

    Saramäki, Jari

    2013-01-01

    The concept of temporal networks is an extension of complex networks as a modeling framework to include information on when interactions between nodes happen. Many studies of the last decade examine how the static network structure affect dynamic systems on the network. In this traditional approach  the temporal aspects are pre-encoded in the dynamic system model. Temporal-network methods, on the other hand, lift the temporal information from the level of system dynamics to the mathematical representation of the contact network itself. This framework becomes particularly useful for cases where there is a lot of structure and heterogeneity both in the timings of interaction events and the network topology. The advantage compared to common static network approaches is the ability to design more accurate models in order to explain and predict large-scale dynamic phenomena (such as, e.g., epidemic outbreaks and other spreading phenomena). On the other hand, temporal network methods are mathematically and concept...

  18. Graphics Processing Unit-Enhanced Genetic Algorithms for Solving the Temporal Dynamics of Gene Regulatory Networks.

    Science.gov (United States)

    García-Calvo, Raúl; Guisado, J L; Diaz-Del-Rio, Fernando; Córdoba, Antonio; Jiménez-Morales, Francisco

    2018-01-01

    Understanding the regulation of gene expression is one of the key problems in current biology. A promising method for that purpose is the determination of the temporal dynamics between known initial and ending network states, by using simple acting rules. The huge amount of rule combinations and the nonlinear inherent nature of the problem make genetic algorithms an excellent candidate for finding optimal solutions. As this is a computationally intensive problem that needs long runtimes in conventional architectures for realistic network sizes, it is fundamental to accelerate this task. In this article, we study how to develop efficient parallel implementations of this method for the fine-grained parallel architecture of graphics processing units (GPUs) using the compute unified device architecture (CUDA) platform. An exhaustive and methodical study of various parallel genetic algorithm schemes-master-slave, island, cellular, and hybrid models, and various individual selection methods (roulette, elitist)-is carried out for this problem. Several procedures that optimize the use of the GPU's resources are presented. We conclude that the implementation that produces better results (both from the performance and the genetic algorithm fitness perspectives) is simulating a few thousands of individuals grouped in a few islands using elitist selection. This model comprises 2 mighty factors for discovering the best solutions: finding good individuals in a short number of generations, and introducing genetic diversity via a relatively frequent and numerous migration. As a result, we have even found the optimal solution for the analyzed gene regulatory network (GRN). In addition, a comparative study of the performance obtained by the different parallel implementations on GPU versus a sequential application on CPU is carried out. In our tests, a multifold speedup was obtained for our optimized parallel implementation of the method on medium class GPU over an equivalent

  19. Graphics Processing Unit–Enhanced Genetic Algorithms for Solving the Temporal Dynamics of Gene Regulatory Networks

    Science.gov (United States)

    García-Calvo, Raúl; Guisado, JL; Diaz-del-Rio, Fernando; Córdoba, Antonio; Jiménez-Morales, Francisco

    2018-01-01

    Understanding the regulation of gene expression is one of the key problems in current biology. A promising method for that purpose is the determination of the temporal dynamics between known initial and ending network states, by using simple acting rules. The huge amount of rule combinations and the nonlinear inherent nature of the problem make genetic algorithms an excellent candidate for finding optimal solutions. As this is a computationally intensive problem that needs long runtimes in conventional architectures for realistic network sizes, it is fundamental to accelerate this task. In this article, we study how to develop efficient parallel implementations of this method for the fine-grained parallel architecture of graphics processing units (GPUs) using the compute unified device architecture (CUDA) platform. An exhaustive and methodical study of various parallel genetic algorithm schemes—master-slave, island, cellular, and hybrid models, and various individual selection methods (roulette, elitist)—is carried out for this problem. Several procedures that optimize the use of the GPU’s resources are presented. We conclude that the implementation that produces better results (both from the performance and the genetic algorithm fitness perspectives) is simulating a few thousands of individuals grouped in a few islands using elitist selection. This model comprises 2 mighty factors for discovering the best solutions: finding good individuals in a short number of generations, and introducing genetic diversity via a relatively frequent and numerous migration. As a result, we have even found the optimal solution for the analyzed gene regulatory network (GRN). In addition, a comparative study of the performance obtained by the different parallel implementations on GPU versus a sequential application on CPU is carried out. In our tests, a multifold speedup was obtained for our optimized parallel implementation of the method on medium class GPU over an equivalent

  20. Temporal dominance of emotions: Measuring dynamics of food-related emotions during consumption

    NARCIS (Netherlands)

    Jager, G.; Schlich, P.; Tijssen, I.O.J.M.; Yao, Y.J.; Visalli, M.; Graaf, de C.; Stieger, M.A.

    2014-01-01

    Mapping food-evoked emotions in addition to sensory profiling is topical. In sensory profiling, the Temporal Dominance of Sensation (TDS) method focuses on the assessment of the temporal evolution of dominant sensory attributes over time. We hypothesize that food-evoked emotions also show temporal

  1. Beach-dune dynamics: Spatio-temporal patterns of aeolian sediment transport under complex offshore airflow

    Science.gov (United States)

    Lynch, K.; Jackson, D.; Delgado-Fernandez, I.; Cooper, J. A.; Baas, A. C.; Beyers, M.

    2010-12-01

    This study examines sand transport and wind speed across a beach at Magilligan Strand, Northern Ireland, under offshore wind conditions. Traditionally the offshore component of local wind regimes has been ignored when quantifying beach-dune sediment budgets, with the sheltering effect of the foredune assumed to prohibit grain entrainment on the adjoining beach. Recent investigations of secondary airflow patterns over coastal dunes have suggested this may not be the case, that the turbulent nature of the airflow in these zones enhances sediment transport potential. Beach sediment may be delivered to the dune toe by re-circulating eddies under offshore winds in coastal areas, which may explain much of the dynamics of aeolian dunes on coasts where the dominant wind direction is offshore. The present study investigated aeolian sediment transport patterns under an offshore wind event. Empirical data were collected using load cell traps, for aeolian sediment transport, co-located with 3-D ultrasonic anemometers. The instrument positioning on the sub-aerial beach was informed by prior analysis of the airflow patterns using computational fluid dynamics. The array covered a total beach area of 90 m alongshore by 65 m cross-shore from the dune crest. Results confirm that sediment transport occurred in the ‘sheltered’ area under offshore winds. Over short time and space scales the nature of the transport is highly complex; however, preferential zones for sand entrainment may be identified. Alongshore spatial heterogeneity of sediment transport seems to show a relationship to undulations in the dune crest, while temporal and spatial variations may also be related to the position of the airflow reattachment zone. These results highlight the important feedbacks between flow characteristics and transport in a complex three dimensional surface.

  2. Does carbon availability control temporal dynamics of radial growth in Norway spruce (Picea abies)?

    Science.gov (United States)

    Oberhuber, Walter; Gruber, Andreas; Swidrak, Irene

    2015-04-01

    Intra-annual dynamics of cambial activity and wood formation of coniferous species exposed to soil dryness revealed early culmination of maximum growth in late spring prior to occurrence of more favourable environmental conditions, i.e., repeated high rainfall events during summer (Oberhuber et al. 2014). Because it is well known that plants can adjust carbon allocation patterns to optimize resource uptake under prevailing environmental constraints, we hypothesize that early decrease in radial stem growth is an adaptation to cope with drought stress, which might require an early switch of carbon allocation to belowground organs. Physical blockage of carbon transport in the phloem through girdling causes accumulation and depletion of carbohydrates above and below the girdle, respectively, making this method quite appropriate to investigate carbon relationships in trees. Hence, in a common garden experiment we will manipulate the carbon status of Norway spruce (Picea abies) saplings by phloem blockage at different phenological stages during the growing season. We will present the methodological approach and first results of the study aiming to test the hypothesis that carbon status of the tree affects temporal dynamics of cambial activity and wood formation in conifers under drought. Acknowledgment The research is funded by the Austrian Science Fund (FWF): P25643-B16 "Carbon allocation and growth of Scots pine". Reference Oberhuber W, A Gruber, W Kofler, I Swidrak (2014) Radial stem growth in response to microclimate and soil moisture in a drought-prone mixed coniferous forest at an inner Alpine site. Eur J For Res 133:467-479.

  3. Cross-cultural temperamental differences in infants, children, and adults in the United States of America and Finland.

    Science.gov (United States)

    Gaias, Larissa M; Räikkönen, Katri; Komsi, Niina; Gartstein, Maria A; Fisher, Philip A; Putnam, Samuel P

    2012-04-01

    Cross-cultural differences in temperament were investigated between infants (n = 131, 84 Finns), children (n = 653, 427 Finns), and adults (n = 759, 538 Finns) from the United States of America and Finland. Participants from both cultures completed the Infant Behavior Questionnaire, Childhood Behavior Questionnaire and the Adult Temperament Questionnaire. Across all ages, Americans received higher ratings on temperamental fearfulness than Finnish individuals, and also demonstrated higher levels of other negative affects at several time points. During infancy and adulthood, Finns tended to score higher on positive affect and elements of temperamental effortful control. Gender differences consistent with prior studies emerged cross-culturally, and were found to be more pronounced in the US during childhood and in Finland during adulthood. © 2012 The Authors. Scandinavian Journal of Psychology © 2012 The Scandinavian Psychological Associations.

  4. Cross-cultural Temperamental Differences in Infants, Children, and Adults in the United States of America and Finland

    Science.gov (United States)

    Gaias, Larissa M.; Gartstein, Maria A.; Fisher, Philip A.; Putnam, Samuel P.; Räikkönen, Katri; Komsi, Niina

    2012-01-01

    Cross-cultural differences in temperament were investigated between infants (n = 131, 84 Finns), children (n = 653, 427 Finns), and adults (n = 759, 538 Finns) from the United States of America and Finland. Participants from both cultures completed the Infant Behavior Questionnaire, Childhood Behavior Questionnaire, and the Adult Temperament Questionnaire. Across all ages, Americans received higher ratings on temperamental fearfulness than Finnish individuals, and also demonstrated higher levels of other negative affects at several time points. During infancy and adulthood, Finns tended to score higher on positive affect and elements of temperamental effortful control. Gender differences consistent with prior studies emerged cross-culturally, and were found to be more pronounced in the U.S. during childhood and in Finland during adulthood. PMID:22428997

  5. Do temperamentally shy children process emotion differently than nonshy children? Behavioral, psychophysiological, and gender differences in reticent preschoolers.

    Science.gov (United States)

    Theall-Honey, Laura A; Schmidt, Louis A

    2006-04-01

    We examined regional brain electrical activity (EEG), heart rate, and subjective responses at rest and during the presentation of videoclips designed to elicit a range of emotions (e.g., sadness, anger, happiness, fear) among a sample of healthy 4-year-old children selected for temperamental shyness. We found that shy children exhibited significantly greater relative right central EEG activation at rest and during the presentation of the fear-eliciting videoclip than nonshy children. Shy females displayed greater relative right mid-frontal EEG activation during the sad, happy, and fear videoclips than shy males who displayed greater relative left mid-frontal EEG activation. These results (1) suggest that recent frontal EEG activation/emotion models might be gender-specific and (2) appear to provide the first empirical evidence for recent theoretical notions linking the origins and maintenance of temperamental shyness in children to difficulty in regulating fear responses. Copyright (c) 2006 Wiley Periodicals, Inc.

  6. Temporal dynamics of the longitudinal bunch profile in a laser wakefield accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Heigoldt, Matthias

    2017-05-19

    iterative reconstruction algorithm by our collaborators from Oxford University. A major benefit of their algorithm is to avoid any a priori assumptions about the bunch shape or extrapolation of the spectrum outside the measured range, which are usually necessary in traditional methods. In the presented experiments, the ATLAS 50 TW Ti:Sa based laser system was used in conjunction with a hydrogen-filled gas cell. Under optimized conditions, the shortest bunch duration was determined to 4.8±0.2 fs for single electron bunches with a maximum energy of 650 MeV, a charge of 30 pC and a resulting peak current of 5.7±1.2 kA. In combination with the lengthtunable gas target, the single-shot measurement technique allows for the first time to study the temporal evolution of the electron bunch profile as a function of the acceleration distance. This technique sheds new light onto the acceleration regimes characterized by electron dephasing and laser depletion as well as the involved plasma dynamics. The results show that after electron dephasing a second electron bunch can be injected in the first or subsequent plasma periods. After laser depletion, the first bunch is further found to be dense enough to drive its own beam-driven wakefield. The obtained double bunch structure is well suited for further beam-driven experiments and may enable a demonstration scheme for an energy boost by afterburner acceleration in the near future.

  7. Temporal dynamics of the longitudinal bunch profile in a laser wakefield accelerator

    International Nuclear Information System (INIS)

    Heigoldt, Matthias

    2017-01-01

    iterative reconstruction algorithm by our collaborators from Oxford University. A major benefit of their algorithm is to avoid any a priori assumptions about the bunch shape or extrapolation of the spectrum outside the measured range, which are usually necessary in traditional methods. In the presented experiments, the ATLAS 50 TW Ti:Sa based laser system was used in conjunction with a hydrogen-filled gas cell. Under optimized conditions, the shortest bunch duration was determined to 4.8±0.2 fs for single electron bunches with a maximum energy of 650 MeV, a charge of 30 pC and a resulting peak current of 5.7±1.2 kA. In combination with the lengthtunable gas target, the single-shot measurement technique allows for the first time to study the temporal evolution of the electron bunch profile as a function of the acceleration distance. This technique sheds new light onto the acceleration regimes characterized by electron dephasing and laser depletion as well as the involved plasma dynamics. The results show that after electron dephasing a second electron bunch can be injected in the first or subsequent plasma periods. After laser depletion, the first bunch is further found to be dense enough to drive its own beam-driven wakefield. The obtained double bunch structure is well suited for further beam-driven experiments and may enable a demonstration scheme for an energy boost by afterburner acceleration in the near future.

  8. Transition Dynamics of a Dentate Gyrus-CA3 Neuronal Network during Temporal Lobe Epilepsy

    Directory of Open Access Journals (Sweden)

    Liyuan Zhang

    2017-07-01

    Full Text Available In temporal lobe epilepsy (TLE, the variation of chemical receptor expression underlies the basis of neural network activity shifts, resulting in neuronal hyperexcitability and epileptiform discharges. However, dynamical mechanisms involved in the transitions of TLE are not fully understood, because of the neuronal diversity and the indeterminacy of network connection. Hence, based on Hodgkin–Huxley (HH type neurons and Pinsky–Rinzel (PR type neurons coupling with glutamatergic and GABAergic synaptic connections respectively, we propose a computational framework which contains dentate gyrus (DG region and CA3 region. By regulating the concentration range of N-methyl-D-aspartate-type glutamate receptor (NMDAR, we demonstrate the pyramidal neuron can generate transitions from interictal to seizure discharges. This suggests that enhanced endogenous activity of NMDAR contributes to excitability in pyramidal neuron. Moreover, we conclude that excitatory discharges in CA3 region vary considerably on account of the excitatory currents produced by the excitatory pyramidal neuron. Interestingly, by changing the backprojection connection, we find that glutamatergic type backprojection can promote the dominant frequency of firings and further motivate excitatory counterpropagation from CA3 region to DG region. However, GABAergic type backprojection can reduce firing rate and block morbid counterpropagation, which may be factored into the terminations of TLE. In addition, neuronal diversity dominated network shows weak correlation with different backprojections. Our modeling and simulation studies provide new insights into the mechanisms of seizures generation and connectionism in local hippocampus, along with the synaptic mechanisms of this disease.

  9. Predicting seizures in untreated temporal lobe epilepsy using point-process nonlinear models of heartbeat dynamics.

    Science.gov (United States)

    Valenza, G; Romigi, A; Citi, L; Placidi, F; Izzi, F; Albanese, M; Scilingo, E P; Marciani, M G; Duggento, A; Guerrisi, M; Toschi, N; Barbieri, R

    2016-08-01

    Symptoms of temporal lobe epilepsy (TLE) are frequently associated with autonomic dysregulation, whose underlying biological processes are thought to strongly contribute to sudden unexpected death in epilepsy (SUDEP). While abnormal cardiovascular patterns commonly occur during ictal events, putative patterns of autonomic cardiac effects during pre-ictal (PRE) periods (i.e. periods preceding seizures) are still unknown. In this study, we investigated TLE-related heart rate variability (HRV) through instantaneous, nonlinear estimates of cardiovascular oscillations during inter-ictal (INT) and PRE periods. ECG recordings from 12 patients with TLE were processed to extract standard HRV indices, as well as indices of instantaneous HRV complexity (dominant Lyapunov exponent and entropy) and higher-order statistics (bispectra) obtained through definition of inhomogeneous point-process nonlinear models, employing Volterra-Laguerre expansions of linear, quadratic, and cubic kernels. Experimental results demonstrate that the best INT vs. PRE classification performance (balanced accuracy: 73.91%) was achieved only when retaining the time-varying, nonlinear, and non-stationary structure of heartbeat dynamical features. The proposed approach opens novel important avenues in predicting ictal events using information gathered from cardiovascular signals exclusively.

  10. On the temporal dynamics of sign production: An ERP study in Catalan Sign Language (LSC).

    Science.gov (United States)

    Baus, Cristina; Costa, Albert

    2015-06-03

    This study investigates the temporal dynamics of sign production and how particular aspects of the signed modality influence the early stages of lexical access. To that end, we explored the electrophysiological correlates associated to sign frequency and iconicity in a picture signing task in a group of bimodal bilinguals. Moreover, a subset of the same participants was tested in the same task but naming the pictures instead. Our results revealed that both frequency and iconicity influenced lexical access in sign production. At the ERP level, iconicity effects originated very early in the course of signing (while absent in the spoken modality), suggesting a stronger activation of the semantic properties for iconic signs. Moreover, frequency effects were modulated by iconicity, suggesting that lexical access in signed language is determined by the iconic properties of the signs. These results support the idea that lexical access is sensitive to the same phenomena in word and sign production, but its time-course is modulated by particular aspects of the modality in which a lexical item will be finally articulated. Copyright © 2015 Elsevier B.V. All rights reserved.

  11. Interplay between the temporal dynamics of the vaginal microbiota and human papillomavirus detection.

    Science.gov (United States)

    Brotman, Rebecca M; Shardell, Michelle D; Gajer, Pawel; Tracy, J Kathleen; Zenilman, Jonathan M; Ravel, Jacques; Gravitt, Patti E

    2014-12-01

    We sought to describe the temporal relationship between vaginal microbiota and human papillomavirus (HPV) detection. Thirty-two reproductive-age women self-collected midvaginal swabs twice weekly for 16 weeks (937 samples). Vaginal bacterial communities were characterized by pyrosequencing of barcoded 16S rRNA genes and clustered into 6 community state types (CSTs). Each swab was tested for 37 HPV types. The effects of CSTs on the rate of transition between HPV-negative and HPV-positive states were assessed using continuous-time Markov models. Participants had an average of 29 samples, with HPV point prevalence between 58%-77%. CST was associated with changes in HPV status (PVaginal microbiota dominated by L. gasseri was associated with increased clearance of detectable HPV. Frequent longitudinal sampling is necessary for evaluation of the association between HPV detection and dynamic microbiota. © The Author 2014. Published by Oxford University Press on behalf of the Infectious Diseases Society of America. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  12. Spatio-temporal dynamics of the mirror neuron system during social intentions.

    Science.gov (United States)

    Cacioppo, Stephanie; Bolmont, Mylene; Monteleone, George

    2017-10-27

    Previous research has shown that specific goals and intentions influence a person's allocation of social attention. From a neural viewpoint, a growing body of evidence suggests that the inferior fronto-parietal network, including the mirror neuron system, plays a role in the planning and the understanding of motor intentions. However, it is unclear whether and when the mirror neuron system plays a role in social intentions. Combining a behavioral task with electrical neuroimaging in 22 healthy male participants, the current study investigates whether the temporal brain dynamic of the mirror neuron system differs during two types of social intentions i.e., lust vs. romantic intentions. Our results showed that 62% of the stimuli evoking lustful intentions also evoked romantic intentions, and both intentions were sustained by similar activations of the inferior frontal gyrus and the inferior parietal lobule/angular gyrus for the first 432 ms after stimulus onset. Intentions to not love or not lust, on the other hand, were characterized by earlier differential activations of the inferior fronto-parietal network i.e., as early as 244 ms after stimulus onset. These results suggest that the mirror neuron system may not only code for the motor correlates of intentions, but also for the social meaning of intentions and its valence at both early/automatic and later/more elaborative stages of information processing.

  13. Neural Temporal Dynamics of Facial Emotion Processing: Age Effects and Relationship to Cognitive Function

    Directory of Open Access Journals (Sweden)

    Xiaoyan Liao

    2017-06-01

    Full Text Available This study used event-related potentials (ERPs to investigate the effects of age on neural temporal dynamics of processing task-relevant facial expressions and their relationship to cognitive functions. Negative (sad, afraid, angry, and disgusted, positive (happy, and neutral faces were presented to 30 older and 31 young participants who performed a facial emotion categorization task. Behavioral and ERP indices of facial emotion processing were analyzed. An enhanced N170 for negative faces, in addition to intact right-hemispheric N170 for positive faces, was observed in older adults relative to their younger counterparts. Moreover, older adults demonstrated an attenuated within-group N170 laterality effect for neutral faces, while younger adults showed the opposite pattern. Furthermore, older adults exhibited sustained temporo-occipital negativity deflection over the time range of 200–500 ms post-stimulus, while young adults showed posterior positivity and subsequent emotion-specific frontal negativity deflections. In older adults, decreased accuracy for labeling negative faces was positively correlated with Montreal Cognitive Assessment Scores, and accuracy for labeling neutral faces was negatively correlated with age. These findings suggest that older people may exert more effort in structural encoding for negative faces and there are different response patterns for the categorization of different facial emotions. Cognitive functioning may be related to facial emotion categorization deficits observed in older adults. This may not be attributable to positivity effects: it may represent a selective deficit for the processing of negative facial expressions in older adults.

  14. Spatio-temporal dynamics of impulse responses to figure motion in optic flow neurons.

    Directory of Open Access Journals (Sweden)

    Yu-Jen Lee

    Full Text Available White noise techniques have been used widely to investigate sensory systems in both vertebrates and invertebrates. White noise stimuli are powerful in their ability to rapidly generate data that help the experimenter decipher the spatio-temporal dynamics of neural and behavioral responses. One type of white noise stimuli, maximal length shift register sequences (m-sequences, have recently become particularly popular for extracting response kernels in insect motion vision. We here use such m-sequences to extract the impulse responses to figure motion in hoverfly lobula plate tangential cells (LPTCs. Figure motion is behaviorally important and many visually guided animals orient towards salient features in the surround. We show that LPTCs respond robustly to figure motion in the receptive field. The impulse response is scaled down in amplitude when the figure size is reduced, but its time course remains unaltered. However, a low contrast stimulus generates a slower response with a significantly longer time-to-peak and half-width. Impulse responses in females have a slower time-to-peak than males, but are otherwise similar. Finally we show that the shapes of the impulse response to a figure and a widefield stimulus are very similar, suggesting that the figure response could be coded by the same input as the widefield response.

  15. Spatial and temporal dynamics of dengue fever in Peru: 1994–2006

    Science.gov (United States)

    CHOWELL, G.; TORRE, C. A.; MUNAYCO-ESCATE, C.; SUÁREZ-OGNIO, L.; LÓPEZ-CRUZ, R.; HYMAN, J. M.; CASTILLO-CHAVEZ, C.

    2008-01-01

    SUMMARY The weekly number of dengue cases in Peru, South America, stratified by province for the period 1994–2006 were analysed in conjunction with associated demographic, geographic and climatological data. Estimates of the reproduction number, moderately correlated with population size (Spearman ρ=0·28, P=0·03), had a median of 1·76 (IQR 0·83–4·46). The distributions of dengue attack rates and epidemic durations follow power-law (Pareto) distributions (coefficient of determination >85%, Pjungle areas. Our findings suggest a hierarchy of transmission events during the large 2000–2001 epidemic from large to small population areas when serotypes DEN-3 and DEN-4 were first identified (Spearman ρ=−0·43, P=0·03). The need for spatial and temporal dengue epidemic data with a high degree of resolution not only increases our understanding of the dynamics of dengue but will also generate new hypotheses and provide a platform for testing innovative control policies. PMID:18394264

  16. Amygdala and fusiform gyrus temporal dynamics: Responses to negative facial expressions

    Directory of Open Access Journals (Sweden)

    Rauch Scott L

    2008-05-01

    Full Text Available Abstract Background The amygdala habituates in response to repeated human facial expressions; however, it is unclear whether this brain region habituates to schematic faces (i.e., simple line drawings or caricatures of faces. Using an fMRI block design, 16 healthy participants passively viewed repeated presentations of schematic and human neutral and negative facial expressions. Percent signal changes within anatomic regions-of-interest (amygdala and fusiform gyrus were calculated to examine the temporal dynamics of neural response and any response differences based on face type. Results The amygdala and fusiform gyrus had a within-run "U" response pattern of activity to facial expression blocks. The initial block within each run elicited the greatest activation (relative to baseline and the final block elicited greater activation than the preceding block. No significant differences between schematic and human faces were detected in the amygdala or fusiform gyrus. Conclusion The "U" pattern of response in the amygdala and fusiform gyrus to facial expressions suggests an initial orienting, habituation, and activation recovery in these regions. Furthermore, this study is the first to directly compare brain responses to schematic and human facial expressions, and the similarity in brain responses suggest that schematic faces may be useful in studying amygdala activation.

  17. Temporal dynamics of host molecular responses differentiate symptomatic and asymptomatic influenza a infection.

    Directory of Open Access Journals (Sweden)

    Yongsheng Huang

    2011-08-01

    Full Text Available Exposure to influenza viruses is necessary, but not sufficient, for healthy human hosts to develop symptomatic illness. The host response is an important determinant of disease progression. In order to delineate host molecular responses that differentiate symptomatic and asymptomatic Influenza A infection, we inoculated 17 healthy adults with live influenza (H3N2/Wisconsin and examined changes in host peripheral blood gene expression at 16 timepoints over 132 hours. Here we present distinct transcriptional dynamics of host responses unique to asymptomatic and symptomatic infections. We show that symptomatic hosts invoke, simultaneously, multiple pattern recognition receptors-mediated antiviral and inflammatory responses that may relate to virus-induced oxidative stress. In contrast, asymptomatic subjects tightly regulate these responses and exhibit elevated expression of genes that function in antioxidant responses and cell-mediated responses. We reveal an ab initio molecular signature that strongly correlates to symptomatic clinical disease and biomarkers whose expression patterns best discriminate early from late phases of infection. Our results establish a temporal pattern of host molecular responses that differentiates symptomatic from asymptomatic infections and reveals an asymptomatic host-unique non-passive response signature, suggesting novel putative molecular targets for both prognostic assessment and ameliorative therapeutic intervention in seasonal and pandemic influenza.

  18. Spatial Temporal Dynamics and Molecular Evolution of Re-Emerging Rabies Virus in Taiwan

    Directory of Open Access Journals (Sweden)

    Yung-Cheng Lin

    2016-03-01

    Full Text Available Taiwan has been recognized by the World Organization for Animal Health as rabies-free since 1961. Surprisingly, rabies virus (RABV was identified in a dead Formosan ferret badger in July 2013. Later, more infected ferret badgers were reported from different geographic regions of Taiwan. In order to know its evolutionary history and spatial temporal dynamics of this virus, phylogeny was reconstructed by maximum likelihood and Bayesian methods based on the full-length of glycoprotein (G, matrix protein (M, and nucleoprotein (N genes. The evolutionary rates and phylogeographic were determined using Beast and SPREAD software. Phylogenetic trees showed a monophyletic group containing all of RABV isolates from Taiwan and it further separated into three sub-groups. The estimated nucleotide substitution rates of G, M, and N genes were between 2.49 × 10−4–4.75 × 10−4 substitutions/site/year, and the mean ratio of dN/dS was significantly low. The time of the most recent common ancestor was estimated around 75, 89, and 170 years, respectively. Phylogeographic analysis suggested the origin of the epidemic could be in Eastern Taiwan, then the Formosan ferret badger moved across the Central Range of Taiwan to western regions and separated into two branches. In this study, we illustrated the evolution history and phylogeographic of RABV in Formosan ferret badgers.

  19. Exploring Spatio-temporal Dynamics of Cellular Automata for Pattern Recognition in Networks

    Science.gov (United States)

    Miranda, Gisele Helena Barboni; Machicao, Jeaneth; Bruno, Odemir Martinez

    2016-11-01

    Network science is an interdisciplinary field which provides an integrative approach for the study of complex systems. In recent years, network modeling has been used for the study of emergent phenomena in many real-world applications. Pattern recognition in networks has been drawing attention to the importance of network characterization, which may lead to understanding the topological properties that are related to the network model. In this paper, the Life-Like Network Automata (LLNA) method is introduced, which was designed for pattern recognition in networks. LLNA uses the network topology as a tessellation of Cellular Automata (CA), whose dynamics produces a spatio-temporal pattern used to extract the feature vector for network characterization. The method was evaluated using synthetic and real-world networks. In the latter, three pattern recognition applications were used: (i) identifying organisms from distinct domains of life through their metabolic networks, (ii) identifying online social networks and (iii) classifying stomata distribution patterns varying according to different lighting conditions. LLNA was compared to structural measurements and surpasses them in real-world applications, achieving improvement in the classification rate as high as 23%, 4% and 7% respectively. Therefore, the proposed method is a good choice for pattern recognition applications using networks and demonstrates potential for general applicability.

  20. Cue competition affects temporal dynamics of edge-assignment in human visual cortex.

    Science.gov (United States)

    Brooks, Joseph L; Palmer, Stephen E

    2011-03-01

    Edge-assignment determines the perception of relative depth across an edge and the shape of the closer side. Many cues determine edge-assignment, but relatively little is known about the neural mechanisms involved in combining these cues. Here, we manipulated extremal edge and attention cues to bias edge-assignment such that these two cues either cooperated or competed. To index their neural representations, we flickered figure and ground regions at different frequencies and measured the corresponding steady-state visual-evoked potentials (SSVEPs). Figural regions had stronger SSVEP responses than ground regions, independent of whether they were attended or unattended. In addition, competition and cooperation between the two edge-assignment cues significantly affected the temporal dynamics of edge-assignment processes. The figural SSVEP response peaked earlier when the cues causing it cooperated than when they competed, but sustained edge-assignment effects were equivalent for cooperating and competing cues, consistent with a winner-take-all outcome. These results provide physiological evidence that figure-ground organization involves competitive processes that can affect the latency of figural assignment.

  1. Temporal dynamics of physical activity and affect in depressed and nondepressed individuals.

    Science.gov (United States)

    Stavrakakis, Nikolaos; Booij, Sanne H; Roest, Annelieke M; de Jonge, Peter; Oldehinkel, Albertine J; Bos, Elisabeth H

    2015-12-01

    The association between physical activity and affect found in longitudinal observational studies is generally small to moderate. It is unknown how this association generalizes to individuals. The aim of the present study was to investigate interindividual differences in the bidirectional dynamic relationship between physical activity and affect, in depressed and nondepressed individuals, using time-series analysis. A pair-matched sample of 10 depressed and 10 nondepressed participants (mean age = 36.6, SD = 8.9, 30% males) wore accelerometers and completed electronic questionnaires 3 times a day for 30 days. Physical activity was operationalized as the total energy expenditure (EE) per day segment (i.e., 6 hr). The multivariate time series (T = 90) of every individual were analyzed using vector autoregressive modeling (VAR), with the aim to assess direct as well as lagged (i.e., over 1 day) effects of EE on positive and negative affect, and vice versa. Large interindividual differences in the strength, direction and temporal aspects of the relationship between physical activity and positive and negative affect were observed. An exception was the direct (but not the lagged) effect of physical activity on positive affect, which was positive in nearly all individuals. This study showed that the association between physical activity and affect varied considerably across individuals. Thus, while at the group level the effect of physical activity on affect may be small, in some individuals the effect may be clinically relevant. (PsycINFO Database Record (c) 2015 APA, all rights reserved).

  2. Temporal dynamic responses of roots in contrasting tomato genotypes to cadmium tolerance.

    Science.gov (United States)

    Borges, Karina Lima Reis; Salvato, Fernanda; Alcântara, Berenice Kussumoto; Nalin, Rafael Storto; Piotto, Fernando Ângelo; Azevedo, Ricardo Antunes

    2018-04-01

    Despite numerous studies on cadmium (Cd) uptake and accumulation in crops, relatively little is available considering the temporal dynamic of Cd uptake and responses to stress focused on the root system. Here we highlighted the responses to Cd-induced stress in roots of two tomato genotypes contrasting in Cd-tolerance: the tolerant Pusa Ruby and the sensitive Calabash Rouge. Tomato genotypes growing in the presence of 35 μM CdCl 2 exhibited a similar trend of Cd accumulation in tissues, mainly in the root system and overall plants exhibited reduction in the dry matter weight. Both genotypes showed similar trends for malondialdehyde and hydrogen peroxide accumulation with increases when exposed to Cd, being this response more pronounced in the sensitive genotype. When the antioxidant machinery is concerned, in the presence of Cd the reduced glutathione content was decreased in roots while ascorbate peroxidase (APX), glutathione reductase (GR) and glutathione S-transferase (GST) activities were increased in the presence of Cd in the tolerant genotype. Altogether these results suggest APX, GR and GST as the main players of the antioxidant machinery against Cd-induced oxidative stress.

  3. Transition Dynamics of a Dentate Gyrus-CA3 Neuronal Network during Temporal Lobe Epilepsy.

    Science.gov (United States)

    Zhang, Liyuan; Fan, Denggui; Wang, Qingyun

    2017-01-01

    In temporal lobe epilepsy (TLE), the variation of chemical receptor expression underlies the basis of neural network activity shifts, resulting in neuronal hyperexcitability and epileptiform discharges. However, dynamical mechanisms involved in the transitions of TLE are not fully understood, because of the neuronal diversity and the indeterminacy of network connection. Hence, based on Hodgkin-Huxley (HH) type neurons and Pinsky-Rinzel (PR) type neurons coupling with glutamatergic and GABAergic synaptic connections respectively, we propose a computational framework which contains dentate gyrus (DG) region and CA3 region. By regulating the concentration range of N-methyl-D-aspartate-type glutamate receptor (NMDAR), we demonstrate the pyramidal neuron can generate transitions from interictal to seizure discharges. This suggests that enhanced endogenous activity of NMDAR contributes to excitability in pyramidal neuron. Moreover, we conclude that excitatory discharges in CA3 region vary considerably on account of the excitatory currents produced by the excitatory pyramidal neuron. Interestingly, by changing the backprojection connection, we find that glutamatergic type backprojection can promote the dominant frequency of firings and further motivate excitatory counterpropagation from CA3 region to DG region. However, GABAergic type backprojection can reduce firing rate and block morbid counterpropagation, which may be factored into the terminations of TLE. In addition, neuronal diversity dominated network shows weak correlation with different backprojections. Our modeling and simulation studies provide new insights into the mechanisms of seizures generation and connectionism in local hippocampus, along with the synaptic mechanisms of this disease.

  4. Reliability and Minimum Detectable Change of Temporal-Spatial, Kinematic, and Dynamic Stability Measures during Perturbed Gait.

    Directory of Open Access Journals (Sweden)

    Christopher A Rábago

    Full Text Available Temporal-spatial, kinematic variability, and dynamic stability measures collected during perturbation-based assessment paradigms are often used to identify dysfunction associated with gait instability. However, it remains unclear which measures are most reliable for detecting and tracking responses to perturbations. This study systematically determined the between-session reliability and minimum detectable change values of temporal-spatial, kinematic variability, and dynamic stability measures during three types of perturbed gait. Twenty young healthy adults completed two identical testing sessions two weeks apart, comprised of an unperturbed and three perturbed (cognitive, physical, and visual walking conditions in a virtual reality environment. Within each session, perturbation responses were compared to unperturbed walking using paired t-tests. Between-session reliability and minimum detectable change values were also calculated for each measure and condition. All temporal-spatial, kinematic variability and dynamic stability measures demonstrated fair to excellent between-session reliability. Minimal detectable change values, normalized to mean values ranged from 1-50%. Step width mean and variability measures demonstrated the greatest response to perturbations with excellent between-session reliability and low minimum detectable change values. Orbital stability measures demonstrated specificity to perturbation direction and sensitivity with excellent between-session reliability and low minimum detectable change values. We observed substantially greater between-session reliability and lower minimum detectable change values for local stability measures than previously described which may be the result of averaging across trials within a session and using velocity versus acceleration data for reconstruction of state spaces. Across all perturbation types, temporal-spatial, orbital and local measures were the most reliable measures with the

  5. Temporal and spatial variation in recent vehicular emission inventories in China based on dynamic emission factors.

    Science.gov (United States)

    Cai, Hao; Xie, Shaodong

    2013-03-01

    emissions. This paper tracks the temporal and spatial variation characteristics in recent vehicular emission inventories in China based on dynamic emission factors. The fact that CO and NMVOC emissions kept growing at reduced rates and the NOx, PM10, and GHG emissions continued rising rapidly reveals that it was insufficient to bring down the rapid growth of NOx, PM10, and CO2 emissions by merely tightening emission standards and improving fuel quality of motor vehicles. The results will assist decision makers to formulate effective control policies for China's vehicular emissions. The improved methodologies are applicable for routine update of China's vehicular emission inventories.

  6. Monitoring Spatial Variability and Temporal Dynamics of Phragmites Using Unmanned Aerial Vehicles

    Directory of Open Access Journals (Sweden)

    Viktor R. Tóth

    2018-06-01

    Full Text Available Littoral zones of freshwater lakes are exposed to environmental impacts from both terrestrial and aquatic sides, while substantial anthropogenic pressure also affects the high spatial, and temporal variability of the ecotone. In this study, the possibility of monitoring seasonal and spatial changes in reed (Phragmites australis stands using an unmanned aerial vehicle (UAV based remote sensing technique was examined. Stands in eutrophic and mesotrophic parts of Lake Balaton including not deteriorating (stable and deteriorating (die-back patches, were tracked throughout the growing season using a UAV equipped with a Normalized Difference Vegetation Index (NDVI camera. Photophysiological parameters of P. australis were also measured with amplitude modulated fluorescence. Parameters characterizing the dynamics of seasonal changes in NDVI data were used for phenological comparison of eutrophic and mesotrophic, stable and die-back, terrestrial and aquatic, mowed and not-mowed patches of reed. It was shown that stable Phragmites plants from the eutrophic part of the lake reached specific phenological stages up to 3.5 days earlier than plants from the mesotrophic part of the lake. The phenological changes correlated with trophic (total and nitrate-nitrite nitrogen and physical (organic C and clay content properties of the sediment, while only minor relationships with air and water temperature were found. Phenological differences between the stable and die-back stands were even more pronounced, with ~34% higher rates of NDVI increase in stable than die-back patches, while the period of NDVI increase was 16 days longer. Aquatic and terrestrial parts of reed stands showed no phenological differences, although intermediate areas (shallow water parts of stands were found to be less vigorous. Winter mowing of dried Phragmites sped up sprouting and growth of reed in the spring. This study showed that remote sensing-derived photophysiological and phenological

  7. Joint  effects of habitat configuration and temporal stochasticity on population dynamics

    Science.gov (United States)

    Jennifer M. Fraterrigo; Scott M. Pearson; Monica G. Turner

    2009-01-01

    Habitat configuration and temporal stochasticity in the environment are recognized as important drivers of population structure, yet few studies have examined the combined influence of these factors....

  8. Temperamental workers: Psychology, business, and the Humm-Wadsworth Temperament Scale in interwar America.

    Science.gov (United States)

    Lussier, Kira

    2018-05-01

    This article traces the history of a popular interwar psychological test, the Humm-Wadsworth Temperament Scale (HWTS), from its development in the early 1930s to its adoption by corporate personnel departments. In popular articles, trade magazines, and academic journals, industrial psychologist Doncaster Humm and personnel manager Guy Wadsworth trumpeted their scale as a scientific measure of temperament that could ensure efficient hiring practices and harmonious labor relations by screening out "problem employees" and screening for temperamentally "normal" workers. This article demonstrates how concerns about the epistemological and scientific credibility of the HWTS were intimately entangled with concerns about its value to business at every step in the test's development. The HWTS sought to measure the emotional and social dimensions of an individual's personality so as to assess their suitability for work. The practice of temperament testing conjured a vision of the subject whose emotional and social disposition was foundational to their own capacity to find employment, and whose capacity to appropriately express, but regulate, their emotions was foundational to corporate order. The history of the HWTS offers an instructive case of how psychological tests embed social hierarchies, political claims, and economic ideals within their very theoretical and methodological foundations. Although the HWTS itself may have faded from use, the test directly inspired creators of subsequent popular personality tests, such as the Minnesota Multiphasic Personality Inventory and the Myers-Briggs Type Indicator. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

  9. Use of soil moisture dynamics and patterns at different spatio-temporal scales for the investigation of subsurface flow processes

    Directory of Open Access Journals (Sweden)

    T. Blume

    2009-07-01

    Full Text Available Spatial patterns as well as temporal dynamics of soil moisture have a major influence on runoff generation. The investigation of these dynamics and patterns can thus yield valuable information on hydrological processes, especially in data scarce or previously ungauged catchments. The combination of spatially scarce but temporally high resolution soil moisture profiles with episodic and thus temporally scarce moisture profiles at additional locations provides information on spatial as well as temporal patterns of soil moisture at the hillslope transect scale. This approach is better suited to difficult terrain (dense forest, steep slopes than geophysical techniques and at the same time less cost-intensive than a high resolution grid of continuously measuring sensors. Rainfall simulation experiments with dye tracers while continuously monitoring soil moisture response allows for visualization of flow processes in the unsaturated zone at these locations. Data was analyzed at different spacio-temporal scales using various graphical methods, such as space-time colour maps (for the event and plot scale and binary indicator maps (for the long-term and hillslope scale. Annual dynamics of soil moisture and decimeter-scale variability were also investigated. The proposed approach proved to be successful in the investigation of flow processes in the unsaturated zone and showed the importance of preferential flow in the Malalcahuello Catchment, a data-scarce catchment in the Andes of Southern Chile. Fast response times of stream flow indicate that preferential flow observed at the plot scale might also be of importance at the hillslope or catchment scale. Flow patterns were highly variable in space but persistent in time. The most likely explanation for preferential flow in this catchment is a combination of hydrophobicity, small scale heterogeneity in rainfall due to redistribution in the canopy and strong gradients in unsaturated conductivities leading to

  10. Spatial patterns and temporal dynamics of global scale climate-groundwater interactions

    Science.gov (United States)

    Cuthbert, M. O.; Gleeson, T. P.; Moosdorf, N.; Schneider, A. C.; Hartmann, J.; Befus, K. M.; Lehner, B.

    2017-12-01

    The interactions between groundwater and climate are important to resolve in both space and time as they influence mass and energy transfers at Earth's land surface. Despite the significance of these processes, little is known about the spatio-temporal distribution of such interactions globally, and many large-scale climate, hydrological and land surface models oversimplify groundwater or exclude it completely. In this study we bring together diverse global geomatic data sets to map spatial patterns in the sensitivity and degree of connectedness between the water table and the land surface, and use the output from a global groundwater model to assess the locations where the lateral import or export of groundwater is significant. We also quantify the groundwater response time, the characteristic time for groundwater systems to respond to a change in boundary conditions, and map its distribution globally to assess the likely dynamics of groundwater's interaction with climate. We find that more than half of the global land surface significantly exports or imports groundwater laterally. Nearly 40% of Earth's landmass has water tables that are strongly coupled to topography with water tables shallow enough to enable a bi-directional exchange of moisture with the climate system. However, only a small proportion (around 12%) of such regions have groundwater response times of 100 years or less and have groundwater fluxes that would significantly respond to rapid environmental changes over this timescale. We last explore fundamental relationships between aridity, groundwater response times and groundwater turnover times. Our results have wide ranging implications for understanding and modelling changes in Earth's water and energy balance and for informing robust future water management and security decisions.

  11. Temporal dynamics of bacterial and fungal communities in a genetically modified (GM) rice ecosystem.

    Science.gov (United States)

    Lee, Seung-Hoon; Kim, Chang-Gi; Kang, Hojeong

    2011-04-01

    We assessed the temporal dynamics of bacterial and fungal communities in a soil ecosystem supporting genetically modified (GM) rice (Oryza sativa L., ABC-TPSP; fusion of trehalose-6-phosphate synthase and phosphatase). Using terminal restriction fragment length polymorphism analysis and real-time quantitative PCR, we compared bacterial and fungal communities in the soils underlying GM rice (ABC-TPSP), and its host cultivar (Nakdong) during growing seasons and non-growing seasons. Overall, the soils supporting GM and non-GM rice did not differ significantly in diversity indices, including ribotype numbers, for either bacteria or fungi. The diversity index (H) in both the bacterial and fungal communities was correlated with water content, dissolved organic carbon (DOC), and ammonium nitrogen, and the correlation was stronger in fungi than in bacteria. Multivariate analysis showed no differences in microbial community structures between the two crop genotypes, but such differences did appear in time, with significant changes observed after harvest. Gene copy number was estimated as 10(8)~10(11) and 10(5)~10(7) per gram of soil for bacteria and fungi, respectively. As observed for community structure, the rice genotypes did not differ significantly in either bacterial- or fungal-specific gene copy numbers, although we observed a seasonal change in number. We summarize the results of this study as follows. (1) GM rice did not influence soil bacterial and fungal community structures as compared to non-GM rice in our system, (2) both bacterial and fungal communities changed with the growth stage of either rice genotype, (3) fungal communities were less variable than bacterial communities, and (4) although several environmental factors, including ammonium nitrogen and DOC correlated with shifts in microbial community structure, no single factor stood out.

  12. Spatial and temporal dynamics of hepatitis B virus D genotype in Europe and the Mediterranean Basin.

    Directory of Open Access Journals (Sweden)

    Gianguglielmo Zehender

    Full Text Available Hepatitis B virus genotype D can be found in many parts of the world and is the most prevalent strain in south-eastern Europe, the Mediterranean Basin, the Middle East, and the Indian sub-continent. The epidemiological history of the D genotype and its subgenotypes is still obscure because of the scarcity of appropriate studies. We retrieved from public databases a total of 312 gene P sequences of HBV genotype D isolated in various countries throughout the world, and reconstructed the spatio-temporal evolutionary dynamics of the HBV-D epidemic using a bayesian framework.The phylogeographical analysis showed that India had the highest posterior probability of being the location of the tree root, whereas central Asia was the most probable location of the common ancestor of subgenotypes D1-D3. HBV-D5 (identified in native Indian populations diverged from the tree root earlier than D1-D3. The time of the most recent common ancestor (tMRCA of the tree root was 128 years ago, which suggests that the common ancestor of the currently circulating subgenotypes existed in the second half of the XIX century. The mean tMRCA of subgenotypes D1-D3 was between the 1940s and the 1950-60s. On the basis of our phylogeographic reconstruction, it seems that HBV-D reached the Mediterranean area in the middle of the XX century by means of at least two routes: the first pathway (mainly due to the spread of subgenotype D1 crossing the Middle East and reaching north Africa and the eastern Mediterranean, and the second pathway (closely associated with D2 that crossed the former Soviet Union and reached eastern Europe and the Mediterranean through Albania. We hypothesise that the main route of dispersion of genotype D was the unsafe use of injections and drug addiction.

  13. Impact of drought on the temporal dynamics of wood formation in Pinus sylvestris.

    Science.gov (United States)

    Gruber, Andreas; Strobl, Stefan; Veit, Barbara; Oberhuber, Walter

    2010-04-01

    We determined the temporal dynamics of cambial activity and xylem cell differentiation of Scots pine (Pinus sylvestris L.) within a dry inner Alpine valley (750 m a.s.l., Tyrol, Austria), where radial growth is strongly limited by drought in spring. Repeated micro-sampling of the developing tree ring of mature trees was carried out during two contrasting years at two study plots that differ in soil water availability (xeric and dry-mesic sites). In 2007, when air temperature at the beginning of the growing season in April exceeded the long-term mean by 6.4 degrees C, cambial cell division started in early April at both study plots. A delayed onset of cambial activity of c. 2 weeks was found in 2008, when average climate conditions prevailed in spring, indicating that resumption of cambial cell division after winter dormancy is temperature controlled. Cambial cell division consistently ended about the end of June/early July in both study years. Radial enlargement of tracheids started almost 3 weeks earlier in 2007 compared with 2008 at both study plots. At the xeric site, the maximum rate of tracheid production in 2007 and 2008 was reached in early and mid-May, respectively, and c. 2 weeks later at the dry-mesic site. Since in both study years more favorable growing conditions (i.e., an increase in soil water content) were recorded during summer, we suggest a strong sink competition for carbohydrates to mycorrhizal root and shoot growth. Wood formation stopped c. 4 weeks earlier at the xeric compared with the dry-mesic site in both years, indicating a strong influence of drought stress on cell differentiation. This is supported by radial widths of earlywood cells, which were found to be significantly narrower at the xeric than at the dry-mesic site (P drought is strongly influenced by water availability, the onset of cambial activity and cell differentiation is controlled by temperature.

  14. Competitive Semantic Memory Retrieval: Temporal Dynamics Revealed by Event-Related Potentials.

    Directory of Open Access Journals (Sweden)

    Robin Hellerstedt

    Full Text Available Memories compete for retrieval when they are related to a common retrieval cue. Previous research has shown that retrieval of a target memory may lead to subsequent retrieval-induced forgetting (RIF of currently irrelevant competing memories. In the present study, we investigated the time course of competitive semantic retrieval and examined the neurocognitive mechanisms underlying RIF. We contrasted two theoretical accounts of RIF by examining a critical aspect of this memory phenomenon, namely the extent to which it depends on successful retrieval of the target memory. Participants first studied category-exemplar word-pairs (e.g. Fruit-Apple. Next, we recorded electrophysiological measures of brain activity while the participants performed a competitive semantic cued-recall task. In this task, the participants were provided with the studied categories but they were instructed to retrieve other unstudied exemplars (e.g. Fruit-Ma__?. We investigated the event-related potential (ERP correlates of retrieval success by comparing ERPs from successful and failed retrieval trials. To isolate the ERP correlates of continuous retrieval attempts from the ERP correlates of retrieval success, we included an impossible retrieval condition, with incompletable word-stem cues (Drinks-Wy__ and compared it with a non-retrieval presentation baseline condition (Occupation-Dentist. The participants' memory for all the studied exemplars was tested in the final phase of the experiment. Taken together, the behavioural results suggest that RIF is independent of target retrieval. Beyond investigating the mechanisms underlying RIF, the present study also elucidates the temporal dynamics of semantic cued-recall by isolating the ERP correlates of retrieval attempt and retrieval success. The ERP results revealed that retrieval attempt is reflected in a late posterior negativity, possibly indicating construction of candidates for completing the word-stem cue and retrieval

  15. Competitive Semantic Memory Retrieval: Temporal Dynamics Revealed by Event-Related Potentials

    Science.gov (United States)

    Hellerstedt, Robin; Johansson, Mikael

    2016-01-01

    Memories compete for retrieval when they are related to a common retrieval cue. Previous research has shown that retrieval of a target memory may lead to subsequent retrieval-induced forgetting (RIF) of currently irrelevant competing memories. In the present study, we investigated the time course of competitive semantic retrieval and examined the neurocognitive mechanisms underlying RIF. We contrasted two theoretical accounts of RIF by examining a critical aspect of this memory phenomenon, namely the extent to which it depends on successful retrieval of the target memory. Participants first studied category-exemplar word-pairs (e.g. Fruit—Apple). Next, we recorded electrophysiological measures of brain activity while the participants performed a competitive semantic cued-recall task. In this task, the participants were provided with the studied categories but they were instructed to retrieve other unstudied exemplars (e.g. Fruit—Ma__?). We investigated the event-related potential (ERP) correlates of retrieval success by comparing ERPs from successful and failed retrieval trials. To isolate the ERP correlates of continuous retrieval attempts from the ERP correlates of retrieval success, we included an impossible retrieval condition, with incompletable word-stem cues (Drinks—Wy__) and compared it with a non-retrieval presentation baseline condition (Occupation—Dentist). The participants’ memory for all the studied exemplars was tested in the final phase of the experiment. Taken together, the behavioural results suggest that RIF is independent of target retrieval. Beyond investigating the mechanisms underlying RIF, the present study also elucidates the temporal dynamics of semantic cued-recall by isolating the ERP correlates of retrieval attempt and retrieval success. The ERP results revealed that retrieval attempt is reflected in a late posterior negativity, possibly indicating construction of candidates for completing the word-stem cue and retrieval

  16. Spatio-temporal dynamics of cod nursery areas in the Baltic Sea

    Science.gov (United States)

    Hinrichsen, H.-H.; von Dewitz, B.; Lehmann, A.; Bergström, U.; Hüssy, K.

    2017-06-01

    In this study the drift of eastern Baltic cod larvae and juveniles spawned within the historical eastern Baltic cod spawning grounds was investigated by detailed drift model simulations for the years 1971-2010, to examine the spatio-temporal dynamics of environmental suitability in the nursery areas of juvenile cod settlement. The results of the long-term model scenario runs, where juvenile cod were treated as simulated passively drifting particles, enabled us to find strong indications for long-term variations of settlement and potentially the reproduction success of the historically important eastern Baltic cod nursery grounds. Only low proportions of juveniles hatched in the Arkona Basin and in the Gotland Basin were able to settle in their respective spawning ground. Ocean currents were either unfavorable for the juveniles to reach suitable habitats or transported the juveniles to nursery grounds of neighboring subdivisions. Juveniles which hatched in the Bornholm Basin were most widely dispersed and showed the highest settlement probability, while the second highest settlement probability and horizontal dispersal was observed for juveniles originating from the Gdansk Deep. In a long-term perspective, wind-driven transport of larvae/juveniles positively affected the settlement success predominately in the Bornholm Basin and in the Bay of Gdansk. The Bornholm Basin has the potential to contribute on average 54% and the Bay of Gdansk 11% to the production of juveniles in the Baltic Sea. Furthermore, transport of juveniles surviving to the age of settlement with origin in the Bornholm Basin contributed on average 13 and 11% to the total settlement in the Arkona Basin and in the Gdansk Deep, respectively. The time-series of the simulated occupied juvenile cod habitat in the Bornholm Basin and in the Gdansk Deep showed a similar declining trend as the Fulton's K condition factor of demersal 1-group cod, which may confirm the importance of oxygen-dependent habitat

  17. Temporal-spatial dynamics in orthoptera in relation to nutrient availability and plant species richness.

    Directory of Open Access Journals (Sweden)

    Rob J J Hendriks

    Full Text Available Nutrient availability in ecosystems has increased dramatically over the last century. Excess reactive nitrogen deposition is known to negatively impact plant communities, e.g. by changing species composition, biomass and vegetation structure. In contrast, little is known on how such impacts propagate to higher trophic levels. To evaluate how nitrogen deposition affects plants and herbivore communities through time, we used extensive databases of spatially explicit historical records of Dutch plant species and Orthoptera (grasshoppers and crickets, a group of animals that are particularly susceptible to changes in the C:N ratio of their resources. We use robust methods that deal with the unstandardized nature of historical databases to test whether nitrogen deposition levels and plant richness changes influence the patterns of richness change of Orthoptera, taking into account Orthoptera species functional traits. Our findings show that effects indeed also propagate to higher trophic levels. Differences in functional traits affected the temporal-spatial dynamics of assemblages of Orthoptera. While nitrogen deposition affected plant diversity, contrary to our expectations, we could not find a strong significant effect of food related traits. However we found that species with low habitat specificity, limited dispersal capacity and egg deposition in the soil were more negativly affected by nitrogen deposition levels. Despite the lack of significant effect of plant richness or food related traits on Orthoptera, the negative effects of nitrogen detected within certain trait groups (e.g. groups with limited disperse ability could be related to subtle changes in plant abundance and plant quality. Our results, however, suggest that the changes in soil conditions (where many Orthoptera species lay their eggs or other habitat changes driven by nitrogen have a stronger influence than food related traits. To fully evaluate the negative effects of nitrogen

  18. Spatial and temporal dynamics of nitrate fluxes in a mesoscale catchment

    Science.gov (United States)

    Muller, C.; Musolff, A.; Strachauer, U.; Brauns, M.; Tarasova, L.; Merz, R.; Knoeller, K.

    2017-12-01

    Spatially and temporally variable and often superimposing processes like mobilization and turnover of N-species strongly affect nitrate fluxes at catchment outlets. It remains thus challenging to determine dominant nitrate sources to derive an effective river management. Here, we combine data sets from two spatially highly resolved key-date monitoring campaigns of nitrate fluxes along a mesoscale catchment in Germany with four years of monitoring data from two representative sites within the catchment. The study area is characterized by a strong land use gradient from pristine headwaters to lowland sub-catchments with intense agricultural land use and wastewater sources. Flow conditions were assessed by a hydrograph separation showing the clear dominance of base flow during both investigations. However, the absolute amounts of discharge differed significantly from each other (outlet: 1.42 m³ s-1 versus 0.43 m³ s-1). Nitrate concentration and flux in the headwater was found to be low. In contrast, nitrate loads further downstream originate from anthropogenic sources such as effluents from wastewater treatment plants (WWTP) and agricultural land use. The agricultural contribution did not vary in terms of nitrate concentration and isotopic signature between the years but in terms of flux. The contrasting amounts of discharge between the years led to a strongly increased relative wastewater contribution with decreasing discharge. This was mainly manifested in elevated δ18O-NO3- values downstream from the wastewater discharge. The four-year monitoring at two sides clearly indicates the chemostatic character of the agricultural N-source and its distinct, yet stable isotopic fingerprint. Denitrification was found to play no dominant role only for controlling nitrate loads in the river. The spatially highly resolved monitoring approach helped to accurately define hot spots of nitrate inputs into the stream while the long-term information allowed a classification of the

  19. Spatial and Temporal Dynamics of Mixotrophic Protists Within a Protected Glacial Lake

    Science.gov (United States)

    DeVaul, S. B.; Sanders, R. W.

    2016-02-01

    Bacterivorous protists are vital components of the aquatic food web as prey for zooplankton and top-down regulators of bacteria. Many bacterivores utilize mixotrophic nutrition that combines photosynthesis with ingestion of particulate matter. Mixotrophic protists are capable of substantial rates of bacterivory - often greater than co-occurring heterotrophic flagellates. It has been argued that mixotrophs may gain a competitive advantage in natural systems due to their ability to utilize photosynthesis during periods of reduced particulate food or phagotrophy during periods of decreased irradiance. A central goal of ecological study has been to understand and ultimately predict the composition of communities in response to varying environmental conditions. The objectives of this study were to determine seasonal abundances and bacterial ingestion rates of heterotrophic, phototrophic and mixotrophic nanoflagellates (hereafter referred to as HNAN, PNAN and MNAN) and identify abiotic drivers that influence spatial and temporal dynamics of these functional groups. Water samples were collected approximately monthly over a 1.5 year period from Lake Lacawac, a 13,000 year old lake with a protected watershed. Trends in MNAN abundance were related to seasonal patterns of thermal stratification and varied with depth. Maximum abundance occurred in the summer epilimnion. Although HNAN abundance tended to be greater than that of MNAN, the latter generally had a greater grazer impact on bacterial biomass within the epilimnion. During the study period, MNAN removed a maximum of 75% of the bacterial biomass daily in the metalimnion. Mixotroph abundance and grazing impact tended to decrease in deeper waters, and was nearly absent in the anaerobic hypolimnion in late summer and early autumn.

  20. Competitive Semantic Memory Retrieval: Temporal Dynamics Revealed by Event-Related Potentials.

    Science.gov (United States)

    Hellerstedt, Robin; Johansson, Mikael

    2016-01-01

    Memories compete for retrieval when they are related to a common retrieval cue. Previous research has shown that retrieval of a target memory may lead to subsequent retrieval-induced forgetting (RIF) of currently irrelevant competing memories. In the present study, we investigated the time course of competitive semantic retrieval and examined the neurocognitive mechanisms underlying RIF. We contrasted two theoretical accounts of RIF by examining a critical aspect of this memory phenomenon, namely the extent to which it depends on successful retrieval of the target memory. Participants first studied category-exemplar word-pairs (e.g. Fruit-Apple). Next, we recorded electrophysiological measures of brain activity while the participants performed a competitive semantic cued-recall task. In this task, the participants were provided with the studied categories but they were instructed to retrieve other unstudied exemplars (e.g. Fruit-Ma__?). We investigated the event-related potential (ERP) correlates of retrieval success by comparing ERPs from successful and failed retrieval trials. To isolate the ERP correlates of continuous retrieval attempts from the ERP correlates of retrieval success, we included an impossible retrieval condition, with incompletable word-stem cues (Drinks-Wy__) and compared it with a non-retrieval presentation baseline condition (Occupation-Dentist). The participants' memory for all the studied exemplars was tested in the final phase of the experiment. Taken together, the behavioural results suggest that RIF is independent of target retrieval. Beyond investigating the mechanisms underlying RIF, the present study also elucidates the temporal dynamics of semantic cued-recall by isolating the ERP correlates of retrieval attempt and retrieval success. The ERP results revealed that retrieval attempt is reflected in a late posterior negativity, possibly indicating construction of candidates for completing the word-stem cue and retrieval monitoring

  1. Microbial Dynamics During a Temporal Sequence of Bioreduction Stimulated by Emulsified Vegetable Oil

    Science.gov (United States)

    Schadt, C. W.; Gihring, T. M.; Yang, Z.; Wu, W.; Green, S.; Overholt, W.; Zhang, G.; Brandt, C. C.; Campbell, J. H.; Carroll, S. C.; Criddle, C.; Jardine, P. M.; Lowe, K.; Mehlhorn, T.; Kostka, J. E.; Watson, D. B.; Brooks, S. C.

    2011-12-01

    Amendments of slow-release substrates (e.g. emulsified vegetable oil; EVO) are potentially pragmatic alternatives to short-lived labile substrates for sustained uranium bioimmobilization within groundwater systems. The spatial and temporal dynamics of geochemical and microbial community changes during EVO amendment are likely to differ significantly from populations stimulated by readily utilizable soluble substrates (e.g. ethanol or acetate). We tracked dynamic changes in geochemistry and microbial communities for 270 days following a one-time EVO injection at the Oak Ridge Integrated Field Research Challenge (ORIFRC) site that resulted in decreased groundwater U concentrations for ~4 months. Pyrosequencing and quantitative PCR of 16S rRNA and dissimilatory sulfite reductase (dsrA) genes from monitoring well samples revealed a rapid decline in bacterial community richness and evenness after EVO injection, concurrent with increased 16S rRNA copy levels, indicating the selection of a narrow group consisting of 10-15 dominant OTUs, rather than a broad community stimulation. By association of the known physiology of close relatives identified in the pyrosequencing analysis, it is possible to infer a hypothesized sequence of microbial functions leading the major changes in electron donors and acceptors in the system. Members of the Firmicutes family Veillonellaceae dominated after injection and most likely catalyzed the initial oil decomposition and utilized the glycerol associated with the oils. Sulfate-reducing bacteria from the genus Desulforegula, known for LCFA oxidation to acetate, also dominated shortly after EVO amendment and are thought to catalyze this process. Acetate and H2 production during LCFA degradation appeared to stimulate NO3-, Fe(III), U(VI), and SO42- reduction by members of the Comamonadaceae, Geobacteriaceae, and Desulfobacterales. Methanogenic archaea flourished late in the experiment and in some samples constituted over 25 % of the total

  2. The Ecuadorian Artisanal Fishery for Large Pelagics: Species Composition and Spatio-Temporal Dynamics.

    Directory of Open Access Journals (Sweden)

    Jimmy Martínez-Ortiz

    Full Text Available The artisanal fisheries of Ecuador operate within one of the most dynamic and productive marine ecosystems of the world. This study investigates the catch composition of the Ecuadorian artisanal fishery for large pelagic fishes, including aspects of its spatio-temporal dynamics. The analyses of this study are based on the most extensive dataset available to date for this fishery: a total of 106,963 trip-landing inspection records collected at its five principal ports during 2008 ‒ 2012. Ecuadorian artisanal fisheries remove a substantial amount of biomass from the upper trophic-level predatory fish community of the eastern tropical Pacific Ocean. It is estimated that at least 135 thousand metric tons (mt (about 15.5 million fish were landed in the five principal ports during the study period. The great novelty of Ecuadorian artisanal fisheries is the "oceanic-artisanal" fleet component, which consists of mother-ship (nodriza boats with their towed fiber-glass skiffs (fibras operating with pelagic longlines. This fleet has fully expanded into oceanic waters as far offshore as 100°W, west of the Galapagos Archipelago. It is estimated that nodriza operations produce as much as 80% of the total catches of the artisanal fishery. The remainder is produced by independent fibras operating in inshore waters with pelagic longlines and/or surface gillnets. A multivariate regression tree analysis was used to investigate spatio-environmental effects on the nodriza fleet (n = 6,821 trips. The catch species composition of the nodriza fleet is strongly influenced by the northwesterly circulation of the Humboldt Current along the coast of Peru and its associated cold waters masses. The target species and longline gear-type used by nodrizas change seasonally with the incursion of cool waters (< 25°C from the south and offshore. During this season, dolphinfish (Coryphaena hippurus dominates the catches. However, in warmer waters, the fishery changes to tuna

  3. The Ecuadorian Artisanal Fishery for Large Pelagics: Species Composition and Spatio-Temporal Dynamics.

    Science.gov (United States)

    Martínez-Ortiz, Jimmy; Aires-da-Silva, Alexandre M; Lennert-Cody, Cleridy E; Maunder, Mark N

    2015-01-01

    The artisanal fisheries of Ecuador operate within one of the most dynamic and productive marine ecosystems of the world. This study investigates the catch composition of the Ecuadorian artisanal fishery for large pelagic fishes, including aspects of its spatio-temporal dynamics. The analyses of this study are based on the most extensive dataset available to date for this fishery: a total of 106,963 trip-landing inspection records collected at its five principal ports during 2008 ‒ 2012. Ecuadorian artisanal fisheries remove a substantial amount of biomass from the upper trophic-level predatory fish community of the eastern tropical Pacific Ocean. It is estimated that at least 135 thousand metric tons (mt) (about 15.5 million fish) were landed in the five principal ports during the study period. The great novelty of Ecuadorian artisanal fisheries is the "oceanic-artisanal" fleet component, which consists of mother-ship (nodriza) boats with their towed fiber-glass skiffs (fibras) operating with pelagic longlines. This fleet has fully expanded into oceanic waters as far offshore as 100°W, west of the Galapagos Archipelago. It is estimated that nodriza operations produce as much as 80% of the total catches of the artisanal fishery. The remainder is produced by independent fibras operating in inshore waters with pelagic longlines and/or surface gillnets. A multivariate regression tree analysis was used to investigate spatio-environmental effects on the nodriza fleet (n = 6,821 trips). The catch species composition of the nodriza fleet is strongly influenced by the northwesterly circulation of the Humboldt Current along the coast of Peru and its associated cold waters masses. The target species and longline gear-type used by nodrizas change seasonally with the incursion of cool waters (< 25°C) from the south and offshore. During this season, dolphinfish (Coryphaena hippurus) dominates the catches. However, in warmer waters, the fishery changes to tuna

  4. Temporal scales, ecosystem dynamics, stakeholders and the valuation of ecosystems services

    NARCIS (Netherlands)

    Hein, Lars; Koppen, van C.S.A.K.; Ierland, van Ekko C.; Leidekker, Jakob

    2016-01-01

    Temporal dimensions are highly relevant to the analysis of ecosystem services and their economic value. In this paper, we provide a framework that can be used for analyzing temporal dimensions of ecosystem services, we present a case study including an analysis of the supply of three ecosystem

  5. Dynamic perfusion CT: Optimizing the temporal resolution for the calculation of perfusion CT parameters in stroke patients

    Energy Technology Data Exchange (ETDEWEB)

    Kaemena, Andreas [Department of Radiology, Charite-Medical University Berlin, Augustenburger Platz 1, D-13353 Berlin (Germany)], E-mail: andreas.kaemena@charite.de; Streitparth, Florian; Grieser, Christian; Lehmkuhl, Lukas [Department of Radiology, Charite-Medical University Berlin, Augustenburger Platz 1, D-13353 Berlin (Germany); Jamil, Basil [Department of Radiotherapy, Charite-Medical University Berlin, Schumannstr. 20/21, D-10117 Berlin (Germany); Wojtal, Katarzyna; Ricke, Jens; Pech, Maciej [Department of Radiology, Charite-Medical University Berlin, Augustenburger Platz 1, D-13353 Berlin (Germany)

    2007-10-15

    Purpose: To assess the influence of different temporal sampling rates on the accuracy of the results from cerebral perfusion CTs in patients with an acute ischemic stroke. Material and methods: Thirty consecutive patients with acute stroke symptoms received a dynamic perfusion CT (LightSpeed 16, GE). Forty millilitres of iomeprol (Imeron 400) were administered at an injection rate of 4 ml/s. After a scan delay of 7 s, two adjacent 10 mm slices at 80 kV and 190 mA were acquired in a cine mode technique with a cine duration of 49 s. Parametric maps for the blood flow (BF), blood volume (BV) and mean transit time (MTT) were calculated for temporal sampling intervals of 0.5, 1, 2, 3 and 4 s using GE's Perfusion 3 software package. In addition to the quantitative ROI data analysis, a visual perfusion map analysis was performed. Results: The perfusion analysis proved to be technically feasible with all patients. The calculated perfusion values revealed significant differences with regard to the BF, BV and MTT, depending on the employed temporal resolution. The perfusion contrast between ischemic lesions and healthy brain tissue decreased continuously at the lower temporal resolutions. The visual analysis revealed that ischemic lesions were best depicted with sampling intervals of 0.5 and 1 s. Conclusion: We recommend a temporal scan resolution of two images per second for the best detection and depiction of ischemic areas.

  6. Temporal response methods for dynamic measurement of in-process inventory of dissolved nuclear materials

    International Nuclear Information System (INIS)

    Ziri, S.M.; Seefeldt, W.B.

    1977-08-01

    This analysis has demonstrated that a plant's temporal response to perturbation of feed isotope composition can be used to measure the in-process inventory, without suspending plant operations. The main advantages of the temporal response technique over the step-displacement method are (1) it (the temporal response method) obviates the need for large special feed batches, and (2) it obviates the requirement that all the in-process material have a uniform isotopic composition at the beginning of the measurement. The temporal response method holds promise for essentially continuous real-time determination of in-process SNM. However, the temporal response method requires the measurement of the isotopic composition of many samples, and it works best for a stationary random input time series of tracer perturbations. Both of these requirements appear amenable to satisfaction by practical equipment and procedures if the benefits are deemed sufficiently worthwhile

  7. Temporal bird community dynamics are strongly affected by landscape fragmentation in a Central American tropical forest region

    Science.gov (United States)

    Blandón, A.C.; Perelman, S.B.; Ramírez, M.; López, A.; Javier, O.; Robbins, Chandler S.

    2016-01-01

    Habitat loss and fragmentation are considered the main causes of species extinctions, particularly in tropical ecosystems. The objective of this work was to evaluate the temporal dynamics of tropical bird communities in landscapes with different levels of fragmentation in eastern Guatemala. We evaluated five bird community dynamic parameters for forest specialists and generalists: (1) species extinction, (2) species turnover, (3) number of colonizing species, (4) relative species richness, and (5) a homogeneity index. For each of 24 landscapes, community dynamic parameters were estimated from bird point count data, for the 1998–1999 and 2008–2009 periods, accounting for species’ detection probability. Forest specialists had higher extinction rates and a smaller number of colonizing species in landscapes with higher fragmentation, thus having lower species richness in both time periods. Alternatively, forest generalists elicited a completely different pattern, showing a curvilinear association to forest fragmentation for most parameters. Thus, greater community dynamism for forest generalists was shown in landscapes with intermediate levels of fragmentation. Our study supports general theory regarding the expected negative effects of habitat loss and fragmentation on the temporal dynamics of biotic communities, particularly for forest specialists, providing strong evidence from understudied tropical bird communities.

  8. Development of temperamental effortful control mediates the relationship between maturation of the prefrontal cortex and psychopathology during adolescence: A 4-year longitudinal study

    Directory of Open Access Journals (Sweden)

    Nandita Vijayakumar

    2014-07-01

    Full Text Available This study investigated the relationship between the development of effortful control (EC, a temperamental measure of self-regulation, and concurrent development of three regions of the prefrontal cortex (anterior cingulate cortex, ACC; dorsolateral prefrontal cortex, dlPFC; ventrolateral prefrontal cortex, vlPFC between early- and mid-adolescence. It also examined whether development of EC mediated the relationship between cortical maturation and emotional and behavioral symptoms. Ninety-two adolescents underwent baseline assessments when they were approximately 12 years old and follow-up assessments approximately 4 years later. At each assessment, participants had MRI scans and completed the Early Adolescent Temperament Questionnaire-Revised, as well as measures of depressive and anxious symptoms, and aggressive and risk taking behavior. Cortical thicknesses of the ACC, dlPFC and vlPFC, estimated using the FreeSurfer software, were found to decrease over time. EC also decreased over time in females. Greater thinning of the left ACC was associated with less reduction in EC. Furthermore, change in effortful control mediated the relationship between greater thinning of the left ACC and improvements in socioemotional functioning, including reductions in psychopathological symptoms. These findings highlight the dynamic association between EC and the maturation of the anterior cingulate cortex, and the importance of this relationship for socioemotional functioning during adolescence.

  9. Demand-supply dynamics in tourism systems: A spatio-temporal GIS analysis. The Alberta ski industry case study

    Science.gov (United States)

    Bertazzon, Stefania

    The present research focuses on the interaction of supply and demand of down-hill ski tourism in the province of Alberta. The main hypothesis is that the demand for skiing depends on the socio-economic and demographic characteristics of the population living in the province and outside it. A second, consequent hypothesis is that the development of ski resorts (supply) is a response to the demand for skiing. From the latter derives the hypothesis of a dynamic interaction between supply (ski resorts) and demand (skiers). Such interaction occurs in space, within a range determined by physical distance and the means available to overcome it. The above hypotheses implicitly define interactions that take place in space and evolve over time. The hypotheses are tested by temporal, spatial, and spatio-temporal regression models, using the best available data and the latest commercially available software. The main purpose of this research is to explore analytical techniques to model spatial, temporal, and spatio-temporal dynamics in the context of regional science. The completion of the present research has produced more significant contributions than was originally expected. Many of the unexpected contributions resulted from theoretical and applied needs arising from the application of spatial regression models. Spatial regression models are a new and largely under-applied technique. The models are fairly complex and a considerable amount of preparatory work is needed, prior to their specification and estimation. Most of this work is specific to the field of application. The originality of the solutions devised is increased by the lack of applications in the field of tourism. The scarcity of applications in other fields adds to their value for other applications. The estimation of spatio-temporal models has been only partially attained in the present research. This apparent limitation is due to the novelty and complexity of the analytical methods applied. This opens new

  10. Temporal response methods for dynamic measurement of in-process inventory of dissolved nuclear materials

    International Nuclear Information System (INIS)

    Zivi, S.M.; Seefeldt, W.B.

    1976-01-01

    This analysis demonstrated that a plant's temporal response to perturbations of feed isotope composition can be used to measure the in-process inventory, without suspending plant operations. The main advantage of the temporal response technique over the step-displacement method are (1) it obviates the need for large special feed batches and (2) it obviates the requirement that all the in-process material have a uniform isotopic composition at the beginning of the measurement. The temporal response method holds promise for essentially continuous real-time determination of in-process SNM. The main disadvantage or problem with the temporal response method is that it requires the measurement of the isotopic composition of a great many samples to moderately high accuracy. This requirement appears amenable to solution by a modest effort in instrument development

  11. Temporal dynamics of attentional selection in adult male carriers of the fragile X premutation allele and adult controls

    Directory of Open Access Journals (Sweden)

    Ling Mei Wong

    2015-02-01

    Full Text Available Carriers of the fragile X premutation allele (fXPCs have an expanded CGG trinucleotide repeat size within the emph{FMR1} gene and are at increased risk of developing Fragile X-associated Tremor Ataxia Syndrome (FXTAS. Previous research has shown that male fXPCs with FXTAS exhibit cognitive decline, predominantly in executive functions such as inhibitory control and working memory. Recent evidence suggests fXPCs may also exhibit impairments in processing temporal information. The attentional blink (AB task is often used to examine the dynamics of attentional selection, but disagreements exist as to whether the AB is due to excessive or insufficient attentional control. In this study, we used a variant of the AB task and neuropsychological testing to explore the dynamics of attentional selection, relate AB performance to attentional control, and determine whether fXPCs exhibited temporal and/or attentional control impairments. Participants were adult male fXPCs, aged 18--48 years and asymptomatic for FXTAS (emph{n} = 19 and age-matched male controls (emph{n} = 20. We found that fXPCs did not differ from controls in the AB task, indicating that the temporal dynamics of attentional selection were intact. However, they were impaired in the letter-number sequencing task, a test of attentional control. In the combined fXPC and control group, letter-number sequencing performance correlated positively with AB magnitude. This finding supports models that posit the AB is due to excess attentional control. In our two-pronged analysis approach, we contribute to the theoretical literature in controls by extending the AB literature, and we enhance our understanding of fXPCs by demonstrating that at least some aspects of temporal processing may be spared.

  12. Latent Class Symptom Profiles of Selective Mutism: Identification and Linkage to Temperamental and Social Constructs.

    Science.gov (United States)

    Diliberto, Rachele; Kearney, Christopher A

    2017-11-21

    Selective mutism (SM) is a stable, debilitating psychiatric disorder in which a child fails to speak in most public situations. Considerable debate exists as to the typology of this population, with empirically-based studies pointing to possible dimensions of anxiety, oppositionality, and communication problems, among other aspects. Little work has juxtaposed identified symptom profiles with key temperamental and social constructs often implicated in SM. The present study examined a large, diverse, non-clinical, international sample of children aged 6-10 years with SM to empirically identify symptom profiles and to link these profiles to key aspects of temperament (i.e., emotionality, shyness, sociability, activity) and social functioning (i.e., social problems, social competence). Exploratory and confirmatory factor analysis revealed anxiety/distress, oppositionality, and inattention domains. In addition, latent class analysis revealed nuanced profiles labeled as (1) moderately anxious, oppositional, and inattentive, (2) highly anxious, and moderately oppositional and inattentive, and (3) mildly to moderately anxious, and mildly oppositional and inattentive. Class 2 was the most impaired group and was associated with greater emotionality, shyness, and social problems. Class 3 was the least impaired group and was associated with better sociability and social competence and activity. Class 1 was largely between the other classes, demonstrating less shyness and social problems than Class 2. The results help confirm previous findings of anxiety and oppositional profiles among children with SM but that nuanced classes may indicate subtle variations in impairment. The results have implications not only for subtyping this population but also for refining assessment and case conceptualization strategies and pursuing personalized and perhaps less lengthy treatment.

  13. Using dynamic Brownian bridge movement modelling to measure temporal patterns of habitat selection.

    Science.gov (United States)

    Byrne, Michael E; Clint McCoy, J; Hinton, Joseph W; Chamberlain, Michael J; Collier, Bret A

    2014-09-01

    Accurately describing animal space use is vital to understanding how wildlife use habitat. Improvements in GPS technology continue to facilitate collection of telemetry data at high spatial and temporal resolutions. Application of the recently introduced dynamic Brownian bridge movement model (dBBMM) to such data is promising as the method explicitly incorporates the behavioural heterogeneity of a movement path into the estimated utilization distribution (UD). Utilization distributions defining space use are normally estimated for time-scales ranging from weeks to months, obscuring much of the fine-scale information available from high-volume GPS data sets. By accounting for movement heterogeneity, the dBBMM provides a rigorous, behaviourally based estimate of space use between each set of relocations. Focusing on UDs generated between individual sets of locations allows us to quantify fine-scale circadian variation in habitat use. We used the dBBMM to estimate UDs bounding individual time steps for three terrestrial species with different life histories to illustrate how the method can be used to identify fine-scale variations in habitat use. We also demonstrate how dBBMMs can be used to characterize circadian patterns of habitat selection and link fine-scale patterns of habitat use to behaviour. We observed circadian patterns of habitat use that varied seasonally for a white-tailed deer (Odocoileus virginianus) and coyote (Canis latrans). We found seasonal patterns in selection by the white-tailed deer and were able to link use of conifer forests and agricultural fields to behavioural state of the coyote. Additionally, we were able to quantify the date in which a Rio Grande wild turkey (Meleagris gallopavo intermedia) initiated laying as well as when during the day, she was most likely to visit the nest site to deposit eggs. The ability to quantify circadian patterns of habitat use may have important implications for research and management of wildlife

  14. Temporal dynamics and population genetic structure of Fusarium graminearum in the upper Midwestern United States.

    Science.gov (United States)

    Liang, J M; Xayamongkhon, H; Broz, K; Dong, Y; McCormick, S P; Abramova, S; Ward, T J; Ma, Z H; Kistler, H C

    2014-12-01

    Fusarium graminearum sensu stricto causes Fusarium head blight (FHB) in wheat and barley, and contaminates grains with several trichothecene mycotoxins, causing destructive yield losses and economic impact in the United States. Recently, a F. graminearum strain collected from Minnesota (MN) was determined to produce a novel trichothecene toxin, called NX-2. In order to determine the spatial and temporal dynamics of NX-2 producing strains in MN, North Dakota (ND) and South Dakota (SD), a total of 463 F. graminearum strains were collected from three sampling periods, 1999-2000, 2006-2007 and 2011-2013. A PCR-RFLP based diagnostic test was developed and validated for NX-2 producing strains based on polymorphisms in the Tri1 gene. Trichothecene biosynthesis gene (Tri gene)-based polymerase chain reaction (PCR) assays and ten PCR-restriction fragment length polymorphism (RFLP) markers were used to genotype all strains. NX-2 strains were detected in each sampling period but with a very low overall frequency (2.8%) and were mainly collected near the borders of MN, ND and SD. Strains with the 3ADON chemotype were relatively infrequent in 1999-2000 (4.5%) but increased to 29.4% in 2006-2007 and 17.2% in 2011-2013. The distribution of 3ADON producing strains also expanded from a few border counties between ND and MN in 1999-2000, southward toward the border between SD and MN in 2006-2007 and westward in 2011-2013. Genetic differentiation between 2006-2007 and 2011-2013 populations (3%) was much lower than that between 1999-2000 and 2006-2007 (22%) or 1999-2000 and 2011-2013 (20%) suggesting that most change to population genetic structure of F. graminearum occurred between 1999-2000 and 2006-2007. This change was associated with the emergence of a new population consisting largely of individuals with a 3ADON chemotype. A Bayesian clustering analysis suggested that NX-2 chemotype strains are part of a previously described Upper Midwestern population. However, these analyses

  15. Amazon River dissolved load: temporal dynamics and annual budget from the Andes to the ocean.

    Science.gov (United States)

    Moquet, Jean-Sébastien; Guyot, Jean-Loup; Crave, Alain; Viers, Jérôme; Filizola, Naziano; Martinez, Jean-Michel; Oliveira, Tereza Cristina; Sánchez, Liz Stefanny Hidalgo; Lagane, Christelle; Casimiro, Waldo Sven Lavado; Noriega, Luis; Pombosa, Rodrigo

    2016-06-01

    The aim of the present study is to estimate the export fluxes of major dissolved species at the scale of the Amazon basin, to identify the main parameters controlling their spatial distribution and to identify the role of discharge variability in the variability of the total dissolved solid (TDS) flux through the hydrological cycle. Data are compiled from the monthly hydrochemistry and daily discharge database of the "Programa Climatologico y Hidrologico de la Cuenca Amazonica de Bolivia" (PHICAB) and the HYBAM observatories from 34 stations distributed over the Amazon basin (for the 1983-1992 and 2000-2012 periods, respectively). This paper consists of a first global observation of the fluxes and temporal dynamics of each geomorphological domain of the Amazon basin. Based on mean interannual monthly flux calculations, we estimated that the Amazon basin delivered approximately 272 × 10(6) t year(-1) (263-278) of TDS during the 2003-2012 period, which represents approximately 7 % of the continental inputs to the oceans. This flux is mainly made up by HCO3, Ca and SiO2, reflecting the preferential contributions of carbonate and silicate chemical weathering to the Amazon River Basin. The main tributaries contributing to the TDS flux are the Marañon and Ucayali Rivers (approximately 50 % of the TDS production over 14 % of the Amazon basin area) due to the weathering of carbonates and evaporites drained by their Andean tributaries. An Andes-sedimentary area-shield TDS flux (and specific flux) gradient is observed throughout the basin and is first explained by the TDS concentration contrast between these domains, rather than variability in runoff. This observation highlights that, under tropical context, the weathering flux repartition is primarily controlled by the geomorphological/geological setting and confirms that sedimentary areas are currently active in terms of the production of dissolved load. The log relationships of concentration vs discharge have

  16. Spatial-Temporal Dynamics of High-Resolution Animal Networks: What Can We Learn from Domestic Animals?

    Directory of Open Access Journals (Sweden)

    Shi Chen

    Full Text Available Animal social network is the key to understand many ecological and epidemiological processes. We used real-time location system (RTLS to accurately track cattle position, analyze their proximity networks, and tested the hypothesis of temporal stationarity and spatial homogeneity in these networks during different daily time periods and in different areas of the pen. The network structure was analyzed using global network characteristics (network density, subgroup clustering (modularity, triadic property (transitivity, and dyadic interactions (correlation coefficient from a quadratic assignment procedure at hourly level. We demonstrated substantial spatial-temporal heterogeneity in these networks and potential link between indirect animal-environment contact and direct animal-animal contact. But such heterogeneity diminished if data were collected at lower spatial (aggregated at entire pen level or temporal (aggregated at daily level resolution. The network structure (described by the characteristics such as density, modularity, transitivity, etc. also changed substantially at different time and locations. There were certain time (feeding and location (hay that the proximity network structures were more consistent based on the dyadic interaction analysis. These results reveal new insights for animal network structure and spatial-temporal dynamics, provide more accurate descriptions of animal social networks, and allow more accurate modeling of multiple (both direct and indirect disease transmission pathways.

  17. Quantifying temporal trends in fisheries abundance using Bayesian dynamic linear models: A case study of riverine Smallmouth Bass populations

    Science.gov (United States)

    Schall, Megan K.; Blazer, Vicki S.; Lorantas, Robert M.; Smith, Geoffrey; Mullican, John E.; Keplinger, Brandon J.; Wagner, Tyler

    2018-01-01

    Detecting temporal changes in fish abundance is an essential component of fisheries management. Because of the need to understand short‐term and nonlinear changes in fish abundance, traditional linear models may not provide adequate information for management decisions. This study highlights the utility of Bayesian dynamic linear models (DLMs) as a tool for quantifying temporal dynamics in fish abundance. To achieve this goal, we quantified temporal trends of Smallmouth Bass Micropterus dolomieu catch per effort (CPE) from rivers in the mid‐Atlantic states, and we calculated annual probabilities of decline from the posterior distributions of annual rates of change in CPE. We were interested in annual declines because of recent concerns about fish health in portions of the study area. In general, periods of decline were greatest within the Susquehanna River basin, Pennsylvania. The declines in CPE began in the late 1990s—prior to observations of fish health problems—and began to stabilize toward the end of the time series (2011). In contrast, many of the other rivers investigated did not have the same magnitude or duration of decline in CPE. Bayesian DLMs provide information about annual changes in abundance that can inform management and are easily communicated with managers and stakeholders.

  18. Integrating real-time and manual monitored data to predict hillslope soil moisture dynamics with high spatio-temporal resolution using linear and non-linear models

    Science.gov (United States)

    Spatio-temporal variability of soil moisture (') is a challenge that remains to be better understood. A trade-off exists between spatial coverage and temporal resolution when using the manual and real-time ' monitoring methods. This restricted the comprehensive and intensive examination of ' dynamic...

  19. Time-resolved PIV technique for high temporal resolution measurement of mechanical prosthetic aortic valve fluid dynamics.

    Science.gov (United States)

    Kaminsky, R; Morbiducci, U; Rossi, M; Scalise, L; Verdonck, P; Grigioni, M

    2007-02-01

    Prosthetic heart valves (PHVs) have been used to replace diseased native valves for more than five decades. Among these, mechanical PHVs are the most frequently implanted. Unfortunately, these devices still do not achieve ideal behavior and lead to many complications, many of which are related to fluid mechanics. The fluid dynamics of mechanical PHVs are particularly complex and the fine-scale characteristics of such flows call for very accurate experimental techniques. Adequate temporal resolution can be reached by applying time-resolved PIV, a high-resolution dynamic technique which is able to capture detailed chronological changes in the velocity field. The aim of this experimental study is to investigate the evolution of the flow field in a detailed time domain of a commercial bileaflet PHV in a mock-loop mimicking unsteady conditions, by means of time-resolved 2D Particle Image Velocimetry (PIV). The investigated flow field corresponded to the region immediately downstream of the valve plane. Spatial resolution as in "standard" PIV analysis of prosthetic valve fluid dynamics was used. The combination of a Nd:YLF high-repetition-rate double-cavity laser with a high frame rate CMOS camera allowed a detailed, highly temporally resolved acquisition (up to 10000 fps depending on the resolution) of the flow downstream of the PHV. Features that were observed include the non-homogeneity and unsteadiness of the phenomenon and the presence of large-scale vortices within the field, especially in the wake of the valve leaflets. Furthermore, we observed that highly temporally cycle-resolved analysis allowed the different behaviors exhibited by the bileaflet valve at closure to be captured in different acquired cardiac cycles. By accurately capturing hemodynamically relevant time scales of motion, time-resolved PIV characterization can realistically be expected to help designers in improving PHV performance and in furnishing comprehensive validation with experimental data

  20. Spatio-temporal pattern formation, fractals, and chaos in conceptual ecological models as applied to coupled plankton-fish dynamics

    International Nuclear Information System (INIS)

    Medvinskii, Aleksandr B; Tikhonova, Irina A; Tikhonov, D A; Ivanitskii, Genrikh R; Petrovskii, Sergei V; Li, B.-L.; Venturino, E; Malchow, H

    2002-01-01

    The current turn-of-the-century period witnesses the intensive use of the bioproducts of the World Ocean while at the same time calling for precautions to preserve its ecological stability. This requires that biophysical processes in aquatic systems be comprehensively explored and new methods for monitoring their dynamics be developed. While aquatic and terrestrial ecosystems have much in common in terms of their mathematical description, there are essential differences between them. For example, the mobility of oceanic plankton is mainly controlled by diffusion processes, whereas terrestrial organisms naturally enough obey totally different laws. This paper is focused on the processes underlying the dynamics of spatially inhomogeneous plankton communities. We demonstrate that conceptual reaction-diffusion mathematical models are an appropriate tool for investigating both complex spatio-temporal plankton dynamics and the fractal properties of planktivorous fish school walks. (reviews of topical problems)

  1. Dynamics of Neural Responses in Ferret Primary Auditory Cortex: I. Spectro-Temporal Response Field Characterization by Dynamic Ripple Spectra

    National Research Council Canada - National Science Library

    Depireux, Didier A; Simon, Jonathan Z; Klein, David J; Shamma, Shihab A

    1999-01-01

    .... It is calculated here from the responses to elementary 'ripples,' a family of sounds with drifting, sinusoidal, spectral envelopes - the complex spectrotemporal envelope of any broadband, dynamic...

  2. Approximate Entropy as a measure of complexity in sap flow temporal dynamics of two tropical tree species under water deficit

    Directory of Open Access Journals (Sweden)

    Gustavo M. Souza

    2004-09-01

    Full Text Available Approximate Entropy (ApEn, a model-independent statistics to quantify serial irregularities, was used to evaluate changes in sap flow temporal dynamics of two tropical species of trees subjected to water deficit. Water deficit induced a decrease in sap flow of G. ulmifolia, whereas C. legalis held stable their sap flow levels. Slight increases in time series complexity were observed in both species under drought condition. This study showed that ApEn could be used as a helpful tool to assess slight changes in temporal dynamics of physiological data, and to uncover some patterns of plant physiological responses to environmental stimuli.Entropia Aproximada (ApEn, um modelo estatístico independente para quantificar irregularidade em séries temporais, foi utilizada para avaliar alterações na dinâmica temporal do fluxo de seiva em duas espécies arbóreas tropicais submetidas à deficiência hídrica. A deficiência hídrica induziu uma grande redução no fluxo de seiva em G. ulmifolia, enquanto que na espécie C. legalis manteve-se estável. A complexidade das séries temporais foi levemente aumentada sob deficiência hídrica. O estudo mostrou que ApEn pode ser usada como um método para detectar pequenas alterações na dinâmica temporal de dados fisiológicos, e revelar alguns padrões de respostas fisiológicas a estímulos ambientais.

  3. Temporal dynamics of spectral bioindicators evidence biological and ecological differences among functional types in a cork oak open woodland

    Science.gov (United States)

    Cerasoli, Sofia; Costa e Silva, Filipe; Silva, João M. N.

    2016-06-01

    The application of spectral vegetation indices for the purpose of vegetation monitoring and modeling increased largely in recent years. Nonetheless, the interpretation of biophysical properties of vegetation through their spectral signature is still a challenging task. This is particularly true in Mediterranean oak forest characterized by a high spatial and temporal heterogeneity. In this study, the temporal dynamics of vegetation indices expected to be related with green biomass and photosynthetic efficiency were compared for the canopy of trees, the herbaceous layer, and two shrub species: cistus ( Cistus salviifolius) and ulex ( Ulex airensis). coexisting in a cork oak woodland. All indices were calculated from in situ measurements with a FieldSpec3 spectroradiometer (ASD Inc., Boulder, USA). Large differences emerged in the temporal trends and in the correlation between climate and vegetation indices. The relationship between spectral indices and temperature, radiation, and vapor pressure deficit for cork oak was opposite to that observed for the herbaceous layer and cistus. No correlation was observed between rainfall and vegetation indices in cork oak and ulex, but in the herbaceous layer and in the cistus, significant correlations were found. The analysis of spectral vegetation indices with fraction of absorbed PAR (fPAR) and quantum yield of chlorophyll fluorescence ( ΔF/ Fm') evidenced strongest relationships with the indices Normalized Difference Water Index (NDWI) and Photochemical Reflectance Index (PRI)512, respectively. Our results, while confirms the ability of spectral vegetation indices to represent temporal dynamics of biophysical properties of vegetation, evidence the importance to consider ecosystem composition for a correct ecological interpretation of results when the spatial resolution of observations includes different plant functional types.

  4. Spatio-temporal dynamics of a fish predator: Density-dependent and hydrographic effects on Baltic Sea cod population.

    Directory of Open Access Journals (Sweden)

    Valerio Bartolino

    Full Text Available Understanding the mechanisms of spatial population dynamics is crucial for the successful management of exploited species and ecosystems. However, the underlying mechanisms of spatial distribution are generally complex due to the concurrent forcing of both density-dependent species interactions and density-independent environmental factors. Despite the high economic value and central ecological importance of cod in the Baltic Sea, the drivers of its spatio-temporal population dynamics have not been analytically investigated so far. In this paper, we used an extensive trawl survey dataset in combination with environmental data to investigate the spatial dynamics of the distribution of the Eastern Baltic cod during the past three decades using Generalized Additive Models. The results showed that adult cod distribution was mainly affected by cod population size, and to a minor degree by small-scale hydrological factors and the extent of suitable reproductive areas. As population size decreases, the cod population concentrates to the southern part of the Baltic Sea, where the preferred more marine environment conditions are encountered. Using the fitted models, we predicted the Baltic cod distribution back to the 1970s and a temporal index of cod spatial occupation was developed. Our study will contribute to the management and conservation of this important resource and of the ecosystem where it occurs, by showing the forces shaping its spatial distribution and therefore the potential response of the population to future exploitation and environmental changes.

  5. Discrete simulations of spatio-temporal dynamics of small water bodies under varied stream flow discharges

    Science.gov (United States)

    Daya Sagar, B. S.

    2005-01-01

    Spatio-temporal patterns of small water bodies (SWBs) under the influence of temporally varied stream flow discharge are simulated in discrete space by employing geomorphologically realistic expansion and contraction transformations. Cascades of expansion-contraction are systematically performed by synchronizing them with stream flow discharge simulated via the logistic map. Templates with definite characteristic information are defined from stream flow discharge pattern as the basis to model the spatio-temporal organization of randomly situated surface water bodies of various sizes and shapes. These spatio-temporal patterns under varied parameters (λs) controlling stream flow discharge patterns are characterized by estimating their fractal dimensions. At various λs, nonlinear control parameters, we show the union of boundaries of water bodies that traverse the water body and non-water body spaces as geomorphic attractors. The computed fractal dimensions of these attractors are 1.58, 1.53, 1.78, 1.76, 1.84, and 1.90, respectively, at λs of 1, 2, 3, 3.46, 3.57, and 3.99. These values are in line with general visual observations.

  6. Left fronto-temporal dynamics during agreement processing: evidence for feature-specific computations.

    Science.gov (United States)

    Molinaro, Nicola; Barber, Horacio A; Pérez, Alejandro; Parkkonen, Lauri; Carreiras, Manuel

    2013-09-01

    Grammatical agreement is a widespread language phenomenon that indicates formal syntactic relations between words; however, it also conveys basic lexical (e.g. grammatical gender) or semantic (e.g. numerosity) information about a discourse referent. In this study, we focus on the reading of Spanish noun phrases, violating either number or gender determiner-noun agreement compared to grammatical controls. Magnetoencephalographic activity time-locked to the onset of the noun in both types of violation revealed a left-lateralized brain network involving anterior temporal regions (~220 ms) and, later in time, ventro-lateral prefrontal regions (>300 ms). These activations coexist with dependency-specific effects: in an initial step (~170 ms), occipito-temporal regions are employed for fine-grained analysis of the number marking (in Spanish, presence or absence of the suffix '-s'), while anterior temporal regions show increased activation for gender mismatches compared to grammatical controls. The semantic relevance of number agreement dependencies was mainly reflected by left superior temporal increased activity around 340 ms. These findings offer a detailed perspective on the multi-level analyses involved in the initial computation of agreement dependencies, and theoretically support a derivational approach to agreement computation. Copyright © 2013 Elsevier Inc. All rights reserved.

  7. Dynamical Properties of Transient Spatio-Temporal Patterns in Bacterial Colony of Proteus mirabilis

    Science.gov (United States)

    Watanabe, Kazuhiko; Wakita, Jun-ichi; Itoh, Hiroto; Shimada, Hirotoshi; Kurosu, Sayuri; Ikeda, Takemasa; Yamazaki, Yoshihiro; Matsuyama, Tohey; Matsushita, Mitsugu

    2002-02-01

    Spatio-temporal patterns emerged inside a colony of bacterial species Proteus mirabilis on the surface of nutrient-rich semisolid agar medium have been investigated. We observed various patterns composed of the following basic types: propagating stripe, propagating stripe with fixed dislocation, expanding and shrinking target, and rotating spiral. The remarkable point is that the pattern changes immediately when we alter the position for observation, but it returns to the original if we restore the observing position within a few minutes. We further investigated mesoscopic and microscopic properties of the spatio-temporal patterns. It turned out that whenever the spatio-temporal patterns are observed in a colony, the areas are composed of two superimposed monolayers of elongated bacterial cells. In each area they are aligned almost parallel with each other like a two-dimensional nematic liquid crystal, and move collectively and independently of another layer. It has been found that the observed spatio-temporal patterns are explained as the moiré effect.

  8. Discrete simulations of spatio-temporal dynamics of small water bodies under varied stream flow discharges

    Directory of Open Access Journals (Sweden)

    B. S. Daya Sagar

    2005-01-01

    Full Text Available Spatio-temporal patterns of small water bodies (SWBs under the influence of temporally varied stream flow discharge are simulated in discrete space by employing geomorphologically realistic expansion and contraction transformations. Cascades of expansion-contraction are systematically performed by synchronizing them with stream flow discharge simulated via the logistic map. Templates with definite characteristic information are defined from stream flow discharge pattern as the basis to model the spatio-temporal organization of randomly situated surface water bodies of various sizes and shapes. These spatio-temporal patterns under varied parameters (λs controlling stream flow discharge patterns are characterized by estimating their fractal dimensions. At various λs, nonlinear control parameters, we show the union of boundaries of water bodies that traverse the water body and non-water body spaces as geomorphic attractors. The computed fractal dimensions of these attractors are 1.58, 1.53, 1.78, 1.76, 1.84, and 1.90, respectively, at λs of 1, 2, 3, 3.46, 3.57, and 3.99. These values are in line with general visual observations.

  9. Does temperamental instability support a continuity between bipolar II disorder and major depressive disorder?

    Science.gov (United States)

    Benazzi, F

    2006-06-01

    The current categorical split of mood disorders in bipolar disorders and depressive disorders has recently been questioned. Two highly unstable personality features, i.e. the cyclothymic temperament (CT) and borderline personality disorder (BPD), have been found to be more common in bipolar II (BP-II) disorder than in major depressive disorder (MDD). According to Kraepelin, temperamental instability was the "foundation" of his unitary view of mood disorders. The aim was to assess the distributions of the number of CT and borderline personality items between BP-II and MDD. Finding no bi-modal distribution (a "zone of rarity") of these items would support a continuity between the two disorders. an outpatient psychiatry private practice. Interviewer: A senior clinical and mood disorder research psychiatrist. A consecutive sample of 138 BP-II and 71 MDD remitted outpatients. Assessment instruments: The structured clinical interview for DSM-IV Axis I Disorders-Clinician Version (SCID-CV), the SCID-II Personality Questionnaire for self-assessing borderline personality traits (BPT) by patients, the TEMPS-A for self-assessing CT by patients. Interview methods: Patients were interviewed with the SCID-CV to diagnose BP-II and MDD, and then patients self-assessed the questions of the Personality Questionnaire relative to borderline personality, and the questions of the TEMPS-A relative to CT. As clinically significant distress or impairment of functioning is not assessed by the SCID-II Personality Questionnaire, a diagnosis of BPD could not be made, but BPT could be assessed (i.e. all BPD items but not the impairment criterion). The distribution of the number of CT and BPT items was studied by Kernel density estimate. CT and BPT items were significantly more common in BP-II versus MDD. The Kernel density estimate distributions of the number of CT and BPT items in the entire sample had a normal-like shape (i.e. no bi-modality). The expected finding, on the basis of previous

  10. Temperamental reactivity and negative emotionality in uncooperative children referred to specialized paediatric dentistry compared to children in ordinary dental care.

    Science.gov (United States)

    Arnrup, Kristina; Broberg, Anders G; Berggren, Ulf; Bodin, Lennart

    2007-11-01

    Current treatment of children with dental behaviour management problems (DBMP) is based on the presupposition that their difficulties are caused by dental fear, but is this always the case? The aim of this study was to study temperamental reactivity, negative emotionality, and other personal characteristics in relation to DBMP in 8- to 12-year-old children. Forty-six children referred because of DBMP (study group) and 110 children in ordinary dental care (reference group) participated. The EASI tempramental survey assessed temperamental reactivity and negative emotionality, the Child Behaviour Questionnaire internalizing and externalizing behaviour problems, and the Children's Fear Survey Schedule general and dental fears. Cluster analyses and tree-based modelling were used for data analysis. Among the five clusters identified, one could be characterized as 'balanced temperament'. Thirty-five per cent of the reference group compared to only 7% of the study group belonged to this cluster. Negative emotionality was the most important sorting variable. Children referred because of DBMP differed from children in ordinary dental care, not only in dental fear level, but also in personal characteristics. Few of the referred children were characterized by a balanced temperament profile. It is important to consider the dual impact of emotion dysregulation and emotional reactivity in the development of DBMP.

  11. An advanced analysis and modelling the air pollutant concentration temporal dynamics in atmosphere of the industrial cities: Odessa city

    Science.gov (United States)

    Buyadzhi, V. V.; Glushkov, A. V.; Khetselius, O. Yu; Ternovsky, V. B.; Serga, I. N.; Bykowszczenko, N.

    2017-10-01

    Results of analysis and modelling the air pollutant (dioxide of nitrogen) concentration temporal dynamics in atmosphere of the industrial city Odessa are presented for the first time and based on computing by nonlinear methods of the chaos and dynamical systems theories. A chaotic behaviour is discovered and investigated. To reconstruct the corresponding strange chaotic attractor, the time delay and embedding dimension are computed. The former is determined by the methods of autocorrelation function and average mutual information, and the latter is calculated by means of correlation dimension method and algorithm of false nearest neighbours. It is shown that low-dimensional chaos exists in the nitrogen dioxide concentration time series under investigation. Further, the Lyapunov’s exponents spectrum, Kaplan-Yorke dimension and Kolmogorov entropy are computed.

  12. Working-Memory Load and Temporal Myopia in Dynamic Decision Making

    Science.gov (United States)

    Worthy, Darrell A.; Otto, A. Ross; Maddox, W. Todd

    2012-01-01

    We examined the role of working memory (WM) in dynamic decision making by having participants perform decision-making tasks under single-task or dual-task conditions. In 2 experiments participants performed dynamic decision-making tasks in which they chose 1 of 2 options on each trial. The decreasing option always gave a larger immediate reward…

  13. Dynamics of spatio-temporal cellular structures Henri Bénard centenary review

    CERN Document Server

    Guyon, Etienne; Wesfreid, J E

    2006-01-01

    The impact of Benard's discovery on 20th century physics is crucial to any modern research area such as fluid dynamics, nonlinear dynamics, and non-equilibrium thermodynamics, just to name a few. This centenary review shows the broad scope and development including modern applications, edited and written by experts in the field.

  14. Temporal carbon dynamics of forests in Washington, US: implications for ecological theory and carbon management

    Science.gov (United States)

    Crystal L. Raymond; Donald. McKenzie

    2014-01-01

    We quantified carbon (C) dynamics of forests in Washington, US using theoretical models of C dynamics as a function of forest age. We fit empirical models to chronosequences of forest inventory data at two scales: a coarse-scale ecosystem classification (ecosections) and forest types (potential vegetation) within ecosections. We hypothesized that analysis at the finer...

  15. Mapping and Characterization of Hydrological Dynamics in a Coastal Marsh Using High Temporal Resolution Sentinel-1A Images

    Directory of Open Access Journals (Sweden)

    Cécile Cazals

    2016-07-01

    Full Text Available In Europe, water levels in wetlands are widely controlled by environmental managers and farmers. However, the influence of these management practices on hydrodynamics and biodiversity remains poorly understood. This study assesses advantages of using radar data from the recently launched Sentinel-1A satellite to monitor hydrological dynamics of the Poitevin marshland in western France. We analyze a time series of 14 radar images acquired in VV and HV polarizations from December 2014 to May 2015 with a 12-day time step. Both polarizations are used with a hysteresis thresholding algorithm which uses both spatial and temporal information to distinguish open water, flooded vegetation and non-flooded grassland. Classification results are compared to in situ piezometric measurements combined with a Digital Terrain Model derived from LiDAR data. Results reveal that open water is successfully detected, whereas flooded grasslands with emergent vegetation and fine-grained patterns are detected with moderate accuracy. Five hydrological regimes are derived from the flood duration and mapped. Analysis of time steps in the time series shows that decreased temporal repetitivity induces significant differences in estimates of flood duration. These results illustrate the great potential to monitor variations in seasonal floods with the high temporal frequency of Sentinel-1A acquisitions.

  16. Temporal dynamics of conflict monitoring and the effects of one or two conflict sources on error-(related) negativity.

    Science.gov (United States)

    Armbrecht, Anne-Simone; Wöhrmann, Anne; Gibbons, Henning; Stahl, Jutta

    2010-09-01

    The present electrophysiological study investigated the temporal development of response conflict and the effects of diverging conflict sources on error(-related) negativity (Ne). Eighteen participants performed a combined stop-signal flanker task, which was comprised of two different conflict sources: a left-right and a go-stop response conflict. It is assumed that the Ne reflects the activity of a conflict monitoring system and thus increases according to (i) the number of conflict sources and (ii) the temporal development of the conflict activity. No increase of the Ne amplitude after double errors (comprising two conflict sources) as compared to hand- and stop-errors (comprising one conflict source) was found, whereas a higher Ne amplitude was observed after a delayed stop-signal onset. The results suggest that the Ne is not sensitive to an increase in the number of conflict sources, but to the temporal dynamics of a go-stop response conflict. Copyright (c) 2010 Elsevier B.V. All rights reserved.

  17. Single-molecule diffusion and conformational dynamics by spatial integration of temporal fluctuations

    KAUST Repository

    Serag, Maged F.

    2014-10-06

    Single-molecule localization and tracking has been used to translate spatiotemporal information of individual molecules to map their diffusion behaviours. However, accurate analysis of diffusion behaviours and including other parameters, such as the conformation and size of molecules, remain as limitations to the method. Here, we report a method that addresses the limitations of existing single-molecular localization methods. The method is based on temporal tracking of the cumulative area occupied by molecules. These temporal fluctuations are tied to molecular size, rates of diffusion and conformational changes. By analysing fluorescent nanospheres and double-stranded DNA molecules of different lengths and topological forms, we demonstrate that our cumulative-area method surpasses the conventional single-molecule localization method in terms of the accuracy of determined diffusion coefficients. Furthermore, the cumulative-area method provides conformational relaxation times of structurally flexible chains along with diffusion coefficients, which together are relevant to work in a wide spectrum of scientific fields.

  18. Single-molecule diffusion and conformational dynamics by spatial integration of temporal fluctuations

    KAUST Repository

    Serag, Maged F.; Abadi, Maram; Habuchi, Satoshi

    2014-01-01

    Single-molecule localization and tracking has been used to translate spatiotemporal information of individual molecules to map their diffusion behaviours. However, accurate analysis of diffusion behaviours and including other parameters, such as the conformation and size of molecules, remain as limitations to the method. Here, we report a method that addresses the limitations of existing single-molecular localization methods. The method is based on temporal tracking of the cumulative area occupied by molecules. These temporal fluctuations are tied to molecular size, rates of diffusion and conformational changes. By analysing fluorescent nanospheres and double-stranded DNA molecules of different lengths and topological forms, we demonstrate that our cumulative-area method surpasses the conventional single-molecule localization method in terms of the accuracy of determined diffusion coefficients. Furthermore, the cumulative-area method provides conformational relaxation times of structurally flexible chains along with diffusion coefficients, which together are relevant to work in a wide spectrum of scientific fields.

  19. The effects of spatial and temporal heterogeneity on the population dynamics of four animal species in a Danish landscape

    Directory of Open Access Journals (Sweden)

    Forchhammer Mads C

    2009-06-01

    Full Text Available Abstract Background Variation in carrying capacity and population return rates is generally ignored in traditional studies of population dynamics. Variation is hard to study in the field because of difficulties controlling the environment in order to obtain statistical replicates, and because of the scale and expense of experimenting on populations. There may also be ethical issues. To circumvent these problems we used detailed simulations of the simultaneous behaviours of interacting animals in an accurate facsimile of a real Danish landscape. The models incorporate as much as possible of the behaviour and ecology of skylarks Alauda arvensis, voles Microtus agrestis, a ground beetle Bembidion lampros and a linyphiid spider Erigone atra. This allows us to quantify and evaluate the importance of spatial and temporal heterogeneity on the population dynamics of the four species. Results Both spatial and temporal heterogeneity affected the relationship between population growth rate and population density in all four species. Spatial heterogeneity accounted for 23–30% of the variance in population growth rate after accounting for the effects of density, reflecting big differences in local carrying capacity associated with the landscape features important to individual species. Temporal heterogeneity accounted for 3–13% of the variance in vole, skylark and spider, but 43% in beetles. The associated temporal variation in carrying capacity would be problematic in traditional analyses of density dependence. Return rates were less than one in all species and essentially invariant in skylarks, spiders and beetles. Return rates varied over the landscape in voles, being slower where there were larger fluctuations in local population sizes. Conclusion Our analyses estimated the traditional parameters of carrying capacities and return rates, but these are now seen as varying continuously over the landscape depending on habitat quality and the mechanisms

  20. Assessing the Utility of Temporally Dynamic Terrain Indices in Alaskan Moose Resource Selection

    Science.gov (United States)

    Jennewein, J. S.; Hebblewhite, M.; Meddens, A. J.; Gilbert, S.; Vierling, L. A.; Boelman, N.; Eitel, J.

    2017-12-01

    The accelerated warming in arctic and boreal regions impacts ecosystem structure and plant species distribution, which have secondary effects on wildlife. In summer months, moose (Alces alces) are especially vulnerable to changes in the availability and quality of forage and foliage cover due to their thermoregulatory needs and high energetic demands post calving. Resource selection functions (RSFs) have been used with great success to model such tradeoffs in habitat selection. Recently, RSFs have expanded to include more dynamic representations of habitat selection through the use of time-varying covariates such as dynamic habitat indices. However, to date few studies have investigated dynamic terrain indices, which incorporate long-term, highly-dynamic meteorological data (e.g., albedo, air temperature) and their utility in modeling habitat selection. The purpose of this study is to compare two dynamic terrain indices (i.e., solar insolation and topographic wetness) to their static counterparts in Alaskan moose resource selection over a ten-year period (2008-2017). Additionally, the utility of a dynamic wind-shelter index is assessed. Three moose datasets (n=130 total), spanning a north-to-south gradient in Alaska, are analyzed independently to assess location-specific resource selection. The newly-released, high-resolution Arctic Digital Elevation Model (5m2) is used as the terrain input into both dynamic and static indices. Dynamic indices are programmed with meteorological data from the North American Regional Analysis (NARR) and NASA's Goddard Earth Sciences Data and Information Services Center (GES-DISC) databases. Static wetness and solar insolation indices are estimated using only topographic parameters (e.g., slope, aspect). Preliminary results from pilot analyses suggest that dynamic terrain indices may provide novel insights into resource selection of moose that could not be gained when using static counterparts. Future applications of such dynamic

  1. Temporal, spatial and ecological dynamics of speciation among amphi-Beringian small mammals

    Science.gov (United States)

    Hope, Andrew G.; Takebayashi, Naoki; Galbreath, Kurt E.; Talbot, Sandra L.; Cook, Joseph A.

    2013-01-01

    Quaternary climate cycles played an important role in promoting diversification across the Northern Hemisphere, although details of the mechanisms driving evolutionary change are still poorly resolved. In a comparative phylogeographical framework, we investigate temporal, spatial and ecological components of evolution within a suite of Holarctic small mammals. We test a hypothesis of simultaneous divergence among multiple taxon pairs, investigating time to coalescence and demographic change for each taxon in response to a combination of climate and geography.

  2. Nonparametric evaluation of dynamic disease risk: a spatio-temporal kernel approach.

    Directory of Open Access Journals (Sweden)

    Zhijie Zhang

    Full Text Available Quantifying the distributions of disease risk in space and time jointly is a key element for understanding spatio-temporal phenomena while also having the potential to enhance our understanding of epidemiologic trajectories. However, most studies to date have neglected time dimension and focus instead on the "average" spatial pattern of disease risk, thereby masking time trajectories of disease risk. In this study we propose a new idea titled "spatio-temporal kernel density estimation (stKDE" that employs hybrid kernel (i.e., weight functions to evaluate the spatio-temporal disease risks. This approach not only can make full use of sample data but also "borrows" information in a particular manner from neighboring points both in space and time via appropriate choice of kernel functions. Monte Carlo simulations show that the proposed method performs substantially better than the traditional (i.e., frequency-based kernel density estimation (trKDE which has been used in applied settings while two illustrative examples demonstrate that the proposed approach can yield superior results compared to the popular trKDE approach. In addition, there exist various possibilities for improving and extending this method.

  3. Temporal dynamics of contrast gain in single cells of the cat striate cortex.

    Science.gov (United States)

    Bonds, A B

    1991-03-01

    The response amplitude of cat striate cortical cells is usually reduced after exposure to high-contrast stimuli. The temporal characteristics and contrast sensitivity of this phenomenon were explored by stimulating cortical cells with drifting gratings in which contrast sequentially incremented and decremented in stepwise fashion over time. All responses showed a clear hysteresis, in which contrast gain dropped on average 0.36 log unit and then returned to baseline values within 60 s. Noticeable gain adjustments were seen in as little as 3 s and with peak contrasts as low as 3%. Contrast adaptation was absent in responses from LGN cells. Adaptation was found to depend on temporal frequency of stimulation, with greater and more rapid adaptation at higher temporal frequencies. Two different tests showed that the mechanism controlling response reduction was influenced primarily by stimulus contrast rather than response amplitude. These results support the existence of a rapid and sensitive cortically based system that normalizes the output of cortical cells as a function of local mean contrast. Control of the adaptation appears to arise at least in part across a population of cells, which is consistent with the idea that the gain control serves to limit the information converging from many cells onto subsequent processing areas.

  4. Cdc42 and RhoA reveal different spatio-temporal dynamics upon local stimulation with Semaphorin-3A

    Directory of Open Access Journals (Sweden)

    Federico eIseppon

    2015-08-01

    Full Text Available Small RhoGTPases, such as Cdc42 and RhoA, are key players in integrating external cues and intracellular signaling pathways that regulate growth cone (GC motility. Indeed, Cdc42 is involved in actin polymerization and filopodia formation, whereas RhoA induces GC collapse and neurite retraction through actomyosin contraction. In this study we employed Förster Resonance Energy Transfer (FRET microscopy to study the spatio-temporal dynamics of Cdc42 and RhoA in GCs in response to local Semaphorin-3A stimulation obtained with lipid vesicles filled with Semaphorin-3A and positioned near the selected GC using optical tweezers. We found that Cdc42 and RhoA were activated at the leading edge of NG108-15 neuroblastoma cells during spontaneous cycles of protrusion and retraction, respectively. The release of Semaphorin-3A brought to a progressive activation of RhoA within 30 seconds from the stimulus in the central region of the GC that collapsed and retracted. In contrast, the same stimulation evoked waves of Cdc42 activation propagating away from the stimulated region. A more localized stimulation obtained with Sema3A coated beads placed on the GC, led to Cdc42 active waves that propagated in a retrograde manner with a mean period of 70 seconds, and followed by GC retraction. Therefore, Semaphorin-3A activates both Cdc42 and RhoA with a complex and different spatial-temporal dynamics.

  5. Global Rice Watch: Spatial-temporal dynamics, driving factors, and impacts of paddy rice agriculture in the world

    Science.gov (United States)

    Xiao, X.; Dong, J.; Zhang, G.; Xin, F.; Li, X.

    2017-12-01

    Paddy rice croplands account for more than 12% of the global cropland areas, and provide food to feed more than 50% of the world population. Spatial patterns and temporal dynamics of paddy rice croplands have changed remarkably in the past decades, driven by growing human population and their changing diet structure, land use (e.g., urbanization, industrialization), climate, markets, and technologies. In this presentation, we will provide a comprehensive review of our current knowledge on (1) the spatial patterns and temporal dynamics of paddy rice croplands from agricultural statistics data and remote sensing approaches; (2) major driving factors for the observed changes in paddy rice areas, including social, economic, climate, land use, markets, crop breeding technology, and farming technology; and (3) major impacts on atmospheric methane concentration, land surface temperature, water resources and use, and so on. We will highlight the results from a few case studies in China and monsoon Asia. We will also call for a global synthesis analysis of paddy rice agriculture, and invite researchers to join the effort to write and edit a book that provides comprehensive and updated knowledge on paddy rice agriculture.

  6. Spatio-temporal dynamics and laterality effects of face inversion, feature presence and configuration, and face outline

    Directory of Open Access Journals (Sweden)

    Ksenija eMarinkovic

    2014-11-01

    Full Text Available Although a crucial role of the fusiform gyrus in face processing has been demonstrated with a variety of methods, converging evidence suggests that face processing involves an interactive and overlapping processing cascade in distributed brain areas. Here we examine the spatio-temporal stages and their functional tuning to face inversion, presence and configuration of inner features, and face contour in healthy subjects during passive viewing. Anatomically-constrained magnetoencephalography (aMEG combines high-density whole-head MEG recordings and distributed source modeling with high-resolution structural MRI. Each person's reconstructed cortical surface served to constrain noise-normalized minimum norm inverse source estimates. The earliest activity was estimated to the occipital cortex at ~100 ms after stimulus onset and was sensitive to an initial coarse level visual analysis. Activity in the right-lateralized ventral temporal area (inclusive of the fusiform gyrus peaked at ~160ms and was largest to inverted faces. Images containing facial features in the veridical and rearranged configuration irrespective of the facial outline elicited intermediate level activity. The M160 stage may provide structural representations necessary for downstream distributed areas to process identity and emotional expression. However, inverted faces additionally engaged the left ventral temporal area at ~180 ms and were uniquely subserved by bilateral processing. This observation is consistent with the dual route model and spared processing of inverted faces in prosopagnosia. The subsequent deflection, peaking at ~240ms in the anterior temporal areas bilaterally, was largest to normal, upright faces. It may reflect initial engagement of the distributed network subserving individuation and familiarity. These results support dynamic models suggesting that processing of unfamiliar faces in the absence of a cognitive task is subserved by a distributed and

  7. Improvement of Lambert-Beer law dynamic range by the use of temporal gates on transmitted light pulse through a scattering medium

    International Nuclear Information System (INIS)

    Yoshino, Hironori; Wada, Kenji; Horinaka, Hiromichi; Cho, Yoshio; Umeda, Tokuo; Osawa, Masahiko.

    1995-01-01

    The Lambert-Beer law holding for pulsed lights transmitted through a scattering medium was examined using a streak camera. The Lambert-Beer law dynamic range is found to be limited by floor levels that are caused by scattered photons and are controllable by the use of a temporal gate on the transmitted pulse. The dynamic range improvement obtained for a scattering medium of 2.8 cm -1 scattering coefficient of a thickness of 80 mm by a temporal gate of 60 ps was as much as 50 dB and the Lambert-Beer law dynamic rang reached to 140 dB. (author)

  8. Dynamic PET reconstruction using temporal patch-based low rank penalty for ROI-based brain kinetic analysis

    International Nuclear Information System (INIS)

    Kim, Kyungsang; Ye, Jong Chul; Son, Young Don; Cho, Zang Hee; Bresler, Yoram; Ra, Jong Beom

    2015-01-01

    Dynamic positron emission tomography (PET) is widely used to measure changes in the bio-distribution of radiopharmaceuticals within particular organs of interest over time. However, to retain sufficient temporal resolution, the number of photon counts in each time frame must be limited. Therefore, conventional reconstruction algorithms such as the ordered subset expectation maximization (OSEM) produce noisy reconstruction images, thus degrading the quality of the extracted time activity curves (TACs). To address this issue, many advanced reconstruction algorithms have been developed using various spatio-temporal regularizations. In this paper, we extend earlier results and develop a novel temporal regularization, which exploits the self-similarity of patches that are collected in dynamic images. The main contribution of this paper is to demonstrate that the correlation of patches can be exploited using a low-rank constraint that is insensitive to global intensity variations. The resulting optimization framework is, however, non-Lipschitz and non-convex due to the Poisson log-likelihood and low-rank penalty terms. Direct application of the conventional Poisson image deconvolution by an augmented Lagrangian (PIDAL) algorithm is, however, problematic due to its large memory requirements, which prevents its parallelization. Thus, we propose a novel optimization framework using the concave-convex procedure (CCCP) by exploiting the Legendre–Fenchel transform, which is computationally efficient and parallelizable. In computer simulation and a real in vivo experiment using a high-resolution research tomograph (HRRT) scanner, we confirm that the proposed algorithm can improve image quality while also extracting more accurate region of interests (ROI) based kinetic parameters. Furthermore, we show that the total reconstruction time for HRRT PET is significantly accelerated using our GPU implementation, which makes the algorithm very practical in clinical environments

  9. Evolution of predator dispersal in relation to spatio-temporal prey dynamics: how not to get stuck in the wrong place!

    Directory of Open Access Journals (Sweden)

    Justin M J Travis

    Full Text Available The eco-evolutionary dynamics of dispersal are recognised as key in determining the responses of populations to environmental changes. Here, by developing a novel modelling approach, we show that predators are likely to have evolved to emigrate more often and become more selective over their destination patch when their prey species exhibit spatio-temporally complex dynamics. We additionally demonstrate that the cost of dispersal can vary substantially across space and time. Perhaps as a consequence of current environmental change, many key prey species are currently exhibiting major shifts in their spatio-temporal dynamics. By exploring similar shifts in silico, we predict that predator populations will be most vulnerable when prey dynamics shift from stable to complex. The more sophisticated dispersal rules, and greater variance therein, that evolve under complex dynamics will enable persistence across a broader range of prey dynamics than the rules which evolve under relatively stable prey conditions.

  10. (No) time for control: Frontal theta dynamics reveal the cost of temporally guided conflict anticipation.

    Science.gov (United States)

    van Driel, Joram; Swart, Jennifer C; Egner, Tobias; Ridderinkhof, K Richard; Cohen, Michael X

    2015-12-01

    During situations of response conflict, cognitive control is characterized by prefrontal theta-band (3- to 8-Hz) activity. It has been shown that cognitive control can be triggered proactively by contextual cues that predict conflict. Here, we investigated whether a pretrial preparation interval could serve as such a cue. This would show that the temporal contingencies embedded in the task can be used to anticipate upcoming conflict. To this end, we recorded electroencephalography (EEG) from 30 human subjects while they performed a version of a Simon task in which the duration of a fixation cross between trials predicted whether the next trial would contain response conflict. Both their behavior and EEG activity showed a consistent but unexpected pattern of results: The conflict effect (increased reaction times and decreased accuracy on conflict as compared to nonconflict trials) was stronger when conflict was cued, and this was associated with stronger conflict-related midfrontal theta activity and functional connectivity. Interestingly, intervals that predicted conflict did show a pretarget increase in midfrontal theta power. These findings suggest that temporally guided expectations of conflict do heighten conflict anticipation, but also lead to less efficiently applied reactive control. We further explored this post-hoc interpretation by means of three behavioral follow-up experiments, in which we used nontemporal cues, semantically informative cues, and neutral cues. Together, this body of results suggests that the counterintuitive cost of conflict cueing may not be uniquely related to the temporal domain, but may instead be related to the implicitness and validity of the cue.

  11. Object Representations in Human Visual Cortex Formed Through Temporal Integration of Dynamic Partial Shape Views.

    Science.gov (United States)

    Orlov, Tanya; Zohary, Ehud

    2018-01-17

    We typically recognize visual objects using the spatial layout of their parts, which are present simultaneously on the retina. Therefore, shape extraction is based on integration of the relevant retinal information over space. The lateral occipital complex (LOC) can represent shape faithfully in such conditions. However, integration over time is sometimes required to determine object shape. To study shape extraction through temporal integration of successive partial shape views, we presented human participants (both men and women) with artificial shapes that moved behind a narrow vertical or horizontal slit. Only a tiny fraction of the shape was visible at any instant at the same retinal location. However, observers perceived a coherent whole shape instead of a jumbled pattern. Using fMRI and multivoxel pattern analysis, we searched for brain regions that encode temporally integrated shape identity. We further required that the representation of shape should be invariant to changes in the slit orientation. We show that slit-invariant shape information is most accurate in the LOC. Importantly, the slit-invariant shape representations matched the conventional whole-shape representations assessed during full-image runs. Moreover, when the same slit-dependent shape slivers were shuffled, thereby preventing their spatiotemporal integration, slit-invariant shape information was reduced dramatically. The slit-invariant representation of the various shapes also mirrored the structure of shape perceptual space as assessed by perceptual similarity judgment tests. Therefore, the LOC is likely to mediate temporal integration of slit-dependent shape views, generating a slit-invariant whole-shape percept. These findings provide strong evidence for a global encoding of shape in the LOC regardless of integration processes required to generate the shape percept. SIGNIFICANCE STATEMENT Visual objects are recognized through spatial integration of features available simultaneously on

  12. A neural model of the temporal dynamics of figure-ground segregation in motion perception.

    Science.gov (United States)

    Raudies, Florian; Neumann, Heiko

    2010-03-01

    How does the visual system manage to segment a visual scene into surfaces and objects and manage to attend to a target object? Based on psychological and physiological investigations, it has been proposed that the perceptual organization and segmentation of a scene is achieved by the processing at different levels of the visual cortical hierarchy. According to this, motion onset detection, motion-defined shape segregation, and target selection are accomplished by processes which bind together simple features into fragments of increasingly complex configurations at different levels in the processing hierarchy. As an alternative to this hierarchical processing hypothesis, it has been proposed that the processing stages for feature detection and segregation are reflected in different temporal episodes in the response patterns of individual neurons. Such temporal epochs have been observed in the activation pattern of neurons as low as in area V1. Here, we present a neural network model of motion detection, figure-ground segregation and attentive selection which explains these response patterns in an unifying framework. Based on known principles of functional architecture of the visual cortex, we propose that initial motion and motion boundaries are detected at different and hierarchically organized stages in the dorsal pathway. Visual shapes that are defined by boundaries, which were generated from juxtaposed opponent motions, are represented at different stages in the ventral pathway. Model areas in the different pathways interact through feedforward and modulating feedback, while mutual interactions enable the communication between motion and form representations. Selective attention is devoted to shape representations by sending modulating feedback signals from higher levels (working memory) to intermediate levels to enhance their responses. Areas in the motion and form pathway are coupled through top-down feedback with V1 cells at the bottom end of the hierarchy

  13. Spatial-temporal-spectral EEG patterns of BOLD functional network connectivity dynamics

    Science.gov (United States)

    Lamoš, Martin; Mareček, Radek; Slavíček, Tomáš; Mikl, Michal; Rektor, Ivan; Jan, Jiří

    2018-06-01

    Objective. Growing interest in the examination of large-scale brain network functional connectivity dynamics is accompanied by an effort to find the electrophysiological correlates. The commonly used constraints applied to spatial and spectral domains during electroencephalogram (EEG) data analysis may leave part of the neural activity unrecognized. We propose an approach that blindly reveals multimodal EEG spectral patterns that are related to the dynamics of the BOLD functional network connectivity. Approach. The blind decomposition of EEG spectrogram by parallel factor analysis has been shown to be a useful technique for uncovering patterns of neural activity. The simultaneously acquired BOLD fMRI data were decomposed by independent component analysis. Dynamic functional connectivity was computed on the component’s time series using a sliding window correlation, and between-network connectivity states were then defined based on the values of the correlation coefficients. ANOVA tests were performed to assess the relationships between the dynamics of between-network connectivity states and the fluctuations of EEG spectral patterns. Main results. We found three patterns related to the dynamics of between-network connectivity states. The first pattern has dominant peaks in the alpha, beta, and gamma bands and is related to the dynamics between the auditory, sensorimotor, and attentional networks. The second pattern, with dominant peaks in the theta and low alpha bands, is related to the visual and default mode network. The third pattern, also with peaks in the theta and low alpha bands, is related to the auditory and frontal network. Significance. Our previous findings revealed a relationship between EEG spectral pattern fluctuations and the hemodynamics of large-scale brain networks. In this study, we suggest that the relationship also exists at the level of functional connectivity dynamics among large-scale brain networks when no standard spatial and spectral

  14. Temporal dynamic of wood formation in Pinus cembra along the alpine treeline ecotone and the effect of climate variables.

    Science.gov (United States)

    Gruber, Andreas; Baumgartner, Daniel; Zimmermann, Jolanda; Oberhuber, Walter

    2009-06-01

    We determined the temporal dynamic of cambial activity and xylem development of stone pine (Pinus cembra L.) throughout the treeline ecotone. Repeated micro-sampling of the developing tree ring was carried out during the growing seasons 2006 and 2007 at the timberline (1950 m a.s.l.), treeline (2110 m a.s.l.) and within the krummholz belt (2180 m a.s.l.) and the influence of climate variables on intra-annual wood formation was determined.At the beginning of both growing seasons, highest numbers of cambial and enlarging cells were observed at the treeline. Soil temperatures at time of initiation of cambial activity were c. 1.5 °C higher at treeline (open canopy) compared to timberline (closed canopy), suggesting that a threshold root-zone temperature is involved in triggering onset of above ground stem growth.The rate of xylem cell production determined in two weekly intervals during June through August 2006-2007 was significantly correlated with air temperature (temperature sums expressed as degree-days and mean daily maximum temperature) at the timberline only. Lack of significant relationships between tracheid production and temperature variables at the treeline and within the krummholz belt support past dendroclimatological studies that more extreme environmental conditions (e.g., wind exposure, frost desiccation, late frost) increasingly control tree growth above timberline.Results of this study revealed that spatial and temporal (i.e. year-to-year) variability in timing and dynamic of wood formation of Pinus cembra is strongly influenced by local site factors within the treeline ecotone and the dynamics of seasonal temperature variation, respectively.

  15. Spatio-temporal image correlation spectroscopy and super-resolution microscopy to quantify molecular dynamics in T cells.

    Science.gov (United States)

    Ashdown, George W; Owen, Dylan M

    2018-02-02

    Many cellular processes are regulated by the spatio-temporal organisation of signalling complexes, cytoskeletal components and membranes. One such example is at the T cell immunological synapse where the retrograde flow of cortical filamentous (F)-actin from the synapse periphery drives signalling protein microclusters towards the synapse centre. The density of this mesh however, makes visualisation and analysis of individual actin fibres difficult due to the resolution limit of conventional microscopy. Recently, super-resolution methods such as structured illumination microscopy (SIM) have surpassed this resolution limit. Here, we apply SIM to better visualise the dense cortical actin meshwork in T cell synapses formed against activating, antibody-coated surfaces and image under total-internal reflection fluorescence (TIRF) illumination. To analyse the observed molecular flows, and the relationship between them, we apply spatio-temporal image correlation spectroscopy (STICS) and its cross-correlation variant (STICCS). We show that the dynamic cortical actin mesh can be visualised with unprecedented detail and that STICS/STICCS can output accurate, quantitative maps of molecular flow velocity and directionality from such data. We find that the actin flow can be disrupted using small molecule inhibitors of actin polymerisation. This combination of imaging and quantitative analysis may provide an important new tool for researchers to investigate the molecular dynamics at cellular length scales. Here we demonstrate the retrograde flow of F-actin which may be important for the clustering and dynamics of key signalling proteins within the plasma membrane, a phenomenon which is vital to correct T cell activation and therefore the mounting of an effective immune response. Copyright © 2018. Published by Elsevier Inc.

  16. Physiological reactions of preschoolers to fear-inducing film clips: Effects of temperamental fearfulness and quality of the parent-child relationship

    NARCIS (Netherlands)

    Gelissen, R.; Koolstra, C.M.; van IJzendoorn, M.H.; Bakermans-Kranenburg, M.J.; van der Veer, R.

    2007-01-01

    This study investigates young children's fright reactions induced by television. The central question concerns the degree to which the impact can be predicted by temperamental fearfulness and the quality of the parent-child relationship. Using a procedure for recording simultaneously skin

  17. Temporal Scalability of Dynamic Volume Data using Mesh Compensated Wavelet Lifting.

    Science.gov (United States)

    Schnurrer, Wolfgang; Pallast, Niklas; Richter, Thomas; Kaup, Andre

    2017-10-12

    Due to their high resolution, dynamic medical 2D+t and 3D+t volumes from computed tomography (CT) and magnetic resonance tomography (MR) reach a size which makes them very unhandy for teleradiologic applications. A lossless scalable representation offers the advantage of a down-scaled version which can be used for orientation or previewing, while the remaining information for reconstructing the full resolution is transmitted on demand. The wavelet transform offers the desired scalability. A very high quality of the lowpass sub-band is crucial in order to use it as a down-scaled representation. We propose an approach based on compensated wavelet lifting for obtaining a scalable representation of dynamic CT and MR volumes with very high quality. The mesh compensation is feasible to model the displacement in dynamic volumes which is mainly given by expansion and contraction of tissue over time. To achieve this, we propose an optimized estimation of the mesh compensation parameters to optimally fit for dynamic volumes. Within the lifting structure, the inversion of the motion compensation is crucial in the update step. We propose to take this inversion directly into account during the estimation step and can improve the quality of the lowpass sub-band by 0.63 dB and 0.43 dB on average for our tested dynamic CT and MR volumes at the cost of an increase of the rate by 2.4% and 1.2% on average.

  18. Locating Temporal Functional Dynamics of Visual Short-Term Memory Binding using Graph Modular Dirichlet Energy

    Science.gov (United States)

    Smith, Keith; Ricaud, Benjamin; Shahid, Nauman; Rhodes, Stephen; Starr, John M.; Ibáñez, Augustin; Parra, Mario A.; Escudero, Javier; Vandergheynst, Pierre

    2017-02-01

    Visual short-term memory binding tasks are a promising early marker for Alzheimer’s disease (AD). To uncover functional deficits of AD in these tasks it is meaningful to first study unimpaired brain function. Electroencephalogram recordings were obtained from encoding and maintenance periods of tasks performed by healthy young volunteers. We probe the task’s transient physiological underpinnings by contrasting shape only (Shape) and shape-colour binding (Bind) conditions, displayed in the left and right sides of the screen, separately. Particularly, we introduce and implement a novel technique named Modular Dirichlet Energy (MDE) which allows robust and flexible analysis of the functional network with unprecedented temporal precision. We find that connectivity in the Bind condition is less integrated with the global network than in the Shape condition in occipital and frontal modules during the encoding period of the right screen condition. Using MDE we are able to discern driving effects in the occipital module between 100-140 ms, coinciding with the P100 visually evoked potential, followed by a driving effect in the frontal module between 140-180 ms, suggesting that the differences found constitute an information processing difference between these modules. This provides temporally precise information over a heterogeneous population in promising tasks for the detection of AD.

  19. Temporal dynamics of disgust and morality: an event-related potential study.

    Directory of Open Access Journals (Sweden)

    Qun Yang

    Full Text Available Disgust is argued to be an emotion that motivates the avoidance of disease-causing entities in the physical domain and unacceptable behaviors in the social-moral domain. Empirical work from behavioral, physiological and brain imaging studies suggests moral judgments are strongly modulated by disgust feelings. Yet, it remains unclear how they are related in the time course of neural processing. Examining the temporal order of disgust emotion and morality could help to clarify the role of disgust in moral judgments. In the present research, a Go/No-Go paradigm was employed to evoke lateralized readiness potentials (LRPs to investigate the temporal order of physical disgust and moral information processing. Participants were asked to give a "yes" or "no" response regarding the physical disgust and moral wrongness of a social act. The results showed that the evaluation of moral information was processed prior to that of physical disgust information. This suggests that moral information is available earlier than physical disgust, and provides more data on the biological heterogeneity between disgust and morality in terms of the time course of neural activity. The findings implicate that physical disgust emotion may not be necessary for people to make moral judgments. They also suggest that some of our moral experience may be more fundamental (than physical disgust experience to our survival and development, as humans spend a considerable amount of time engaging in social interaction.

  20. Stability and dynamics of spatio-temporal structures. Progress report, September 15, 1993--September 14, 1994

    Energy Technology Data Exchange (ETDEWEB)

    Riecke, H.

    1994-05-01

    Goal is to contribute to understanding of localized spatial and spatio-temporal structures far from thermodynamic equilibrium. Here we report on our progress in the study of three classes of systems. (1) We have studied cellular flame structures arising in a circular burner. Using numerical computations we have found a number of traveling-wave structures in which different cells undergo different motion. Most strikingly, we have found a localized wave traveling through the array of steady cells. Results are interpreted using various asymptotic approaches. They are in qualitative agreement with recent experiments. (2) We have continued our investigation of localized waves in binary-mixture convection. Starting from the extended Ginzburg-Landau equations introduced earlier, we have derived equations of motion for interacting fronts connecting the conductive and the convective state. These equations reveal a repulsive interaction between the fronts which implies a new localization mechanism for waves. It is solely due to the long-wavelength mode specific to the extended Ginzburg-Landau equations. The stability properties of the resulting localized waves are in qualitative agreement with very recent experiments. (3) We have extended our investigation of domain structures to include their temporal evolution.

  1. A Statistical Physics Characterization of the Complex Systems Dynamics: Quantifying Complexity from Spatio-Temporal Interactions

    Science.gov (United States)

    Koorehdavoudi, Hana; Bogdan, Paul

    2016-06-01

    Biological systems are frequently categorized as complex systems due to their capabilities of generating spatio-temporal structures from apparent random decisions. In spite of research on analyzing biological systems, we lack a quantifiable framework for measuring their complexity. To fill this gap, in this paper, we develop a new paradigm to study a collective group of N agents moving and interacting in a three-dimensional space. Our paradigm helps to identify the spatio-temporal states of the motion of the group and their associated transition probabilities. This framework enables the estimation of the free energy landscape corresponding to the identified states. Based on the energy landscape, we quantify missing information, emergence, self-organization and complexity for a collective motion. We show that the collective motion of the group of agents evolves to reach the most probable state with relatively lowest energy level and lowest missing information compared to other possible states. Our analysis demonstrates that the natural group of animals exhibit a higher degree of emergence, self-organization and complexity over time. Consequently, this algorithm can be integrated into new frameworks to engineer collective motions to achieve certain degrees of emergence, self-organization and complexity.

  2. The effect of stimulus intensity on response time and accuracy in dynamic, temporally constrained environments.

    Science.gov (United States)

    Causer, J; McRobert, A P; Williams, A M

    2013-10-01

    The ability to make accurate judgments and execute effective skilled movements under severe temporal constraints are fundamental to elite performance in a number of domains including sport, military combat, law enforcement, and medicine. In two experiments, we examine the effect of stimulus strength on response time and accuracy in a temporally constrained, real-world, decision-making task. Specifically, we examine the effect of low stimulus intensity (black) and high stimulus intensity (sequin) uniform designs, worn by teammates, to determine the effect of stimulus strength on the ability of soccer players to make rapid and accurate responses. In both field- and laboratory-based scenarios, professional soccer players viewed developing patterns of play and were required to make a penetrative pass to an attacking player. Significant differences in response accuracy between uniform designs were reported in laboratory- and field-based experiments. Response accuracy was significantly higher in the sequin compared with the black uniform condition. Response times only differed between uniform designs in the laboratory-based experiment. These findings extend the literature into a real-world environment and have significant implications for the design of clothing wear in a number of domains. © 2012 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  3. Modelling estimation and analysis of dynamic processes from image sequences using temporal random closed sets and point processes with application to the cell exocytosis and endocytosis

    OpenAIRE

    Díaz Fernández, Ester

    2010-01-01

    In this thesis, new models and methodologies are introduced for the analysis of dynamic processes characterized by image sequences with spatial temporal overlapping. The spatial temporal overlapping exists in many natural phenomena and should be addressed properly in several Science disciplines such as Microscopy, Material Sciences, Biology, Geostatistics or Communication Networks. This work is related to the Point Process and Random Closed Set theories, within Stochastic Ge...

  4. Temporal dynamics of 2D motion integration for ocular following in macaque monkeys.

    Science.gov (United States)

    Barthélemy, Fréderic V; Fleuriet, Jérome; Masson, Guillaume S

    2010-03-01

    Several recent studies have shown that extracting pattern motion direction is a dynamical process where edge motion is first extracted and pattern-related information is encoded with a small time lag by MT neurons. A similar dynamics was found for human reflexive or voluntary tracking. Here, we bring an essential, but still missing, piece of information by documenting macaque ocular following responses to gratings, unikinetic plaids, and barber-poles. We found that ocular tracking was always initiated first in the grating motion direction with ultra-short latencies (approximately 55 ms). A second component was driven only 10-15 ms later, rotating tracking toward pattern motion direction. At the end the open-loop period, tracking direction was aligned with pattern motion direction (plaids) or the average of the line-ending motion directions (barber-poles). We characterized the dependency on contrast of each component. Both timing and direction of ocular following were quantitatively very consistent with the dynamics of neuronal responses reported by others. Overall, we found a remarkable consistency between neuronal dynamics and monkey behavior, advocating for a direct link between the neuronal solution of the aperture problem and primate perception and action.

  5. Microscale spatio-temporal patterns of oxygen dynamics in permeable intertidal sediments (Skallingen, Denmark)

    DEFF Research Database (Denmark)

    Walpersdorf, Eva Christine; Andersen, Thorbjørn Joest; Elberling, Bo

     Intertidal permeable sediments are, even more than subtidal sediments (Cook et al. 2007), subject to extreme dynamics due to fast changing environ-mental conditions during inundation and emergence. In such systems, a quasi steady state is rarely reached. Integrative in-situ studies covering...

  6. An Agent Model of Temporal Dynamics in Relapse and Recurrence in Depression

    NARCIS (Netherlands)

    Aziz, A.A.; Klein, M.C.A.; Treur, J.

    2009-01-01

    This paper presents a dynamic agent model of recurrences of a depression for an individual. Based on several personal characteristics and a representation of events (i.e. life events or daily hassles) the agent model can simulate whether a human agent that recovered from a depression will fall into

  7. Clock-Controlled Prey-Predator Dynamics : Temporal Segregation of Activities

    OpenAIRE

    Hiroaki, DAIDO; Department of Mathematical Sciences, Graduate School of Engineering, University of Osaka Prefecture

    2003-01-01

    A new type of mathematical model of prey-predator dynamics is proposed. This model takes into account the fact that the daily activities of animals are governed by their body clocks. On the basis of it, we investigate the conditions under which the prey and predator can segregate into diurnal and nocturnal habits on a timescale that is short compared to evolutionary timescales.

  8. The Temporal Dynamics of Regularity Extraction in Non-Human Primates

    Science.gov (United States)

    Minier, Laure; Fagot, Joël; Rey, Arnaud

    2016-01-01

    Extracting the regularities of our environment is one of our core cognitive abilities. To study the fine-grained dynamics of the extraction of embedded regularities, a method combining the advantages of the artificial language paradigm (Saffran, Aslin, & Newport, [Saffran, J. R., 1996]) and the serial response time task (Nissen & Bullemer,…

  9. Variation in predator foraging behavior changes predator-prey spatio-temporal dynamics

    Science.gov (United States)

    1. Foraging underlies the ability of all animals to acquire essential resources and, thus, provides a critical link to understanding population dynamics. A key issue is how variation in foraging behavior affects foraging efficiency and predator-prey interactions in spatially-heterogeneous environmen...

  10. Temporal dynamics of AVS and SEM in sediment of shallow freshwater floodplain lakes

    NARCIS (Netherlands)

    Griethuysen, van C.; Lange, de H.J.; Heuij, van der M.; Bies, S.C.; Gillissen, F.; Koelmans, A.A.

    2006-01-01

    Acid volatile sulfide (AVS) is an operationally defined sulfide fraction, which is considered important for trace metal fate in reduced sediments. Understanding AVS formation rates is important for the management of metal polluted sediment. However, little lis known about the fate and dynamics of

  11. The cascade from local to global dust storms on Mars: Temporal and spatial thresholds on thermal and dynamical feedback

    Science.gov (United States)

    Toigo, Anthony D.; Richardson, Mark I.; Wang, Huiqun; Guzewich, Scott D.; Newman, Claire E.

    2018-03-01

    We use the MarsWRF general circulation model to examine the temporal and spatial response of the atmosphere to idealized local and regional dust storm radiative heating. The ability of storms to modify the atmosphere away from the location of dust heating is a likely prerequisite for dynamical feedbacks that aid the growth of storms beyond the local scale, while the ability of storms to modify the atmosphere after the cessation of dust radiative heating is potentially important in preconditioning the atmosphere prior to large scale storms. Experiments were conducted over a range of static, prescribed storm sizes, durations, optical depth strengths, locations, and vertical extents of dust heating. Our results show that for typical sizes (order 105 km2) and durations (1-10 sols) of local dust storms, modification of the atmosphere is less than the typical variability of the unperturbed (storm-free) state. Even if imposed on regional storm length scales (order 106 km2), a 1-sol duration storm similarly does not significantly modify the background atmosphere. Only when imposed for 10 sols does a regional dust storm create a significant impact on the background atmosphere, allowing for the possibility of self-induced dynamical storm growth. These results suggest a prototype for how the subjective observational categorization of storms may be related to objective dynamical growth feedbacks that only become available to storms after they achieve a threshold size and duration, or if they grow into an atmosphere preconditioned by a prior large and sustained storm.

  12. Dynamic sensory description of Rioja Alavesa red wines made by different winemaking practices by using Temporal Dominance of Sensations.

    Science.gov (United States)

    Etaio, Iñaki; Meillon, Sophie; Pérez-Elortondo, Francisco J; Schlich, Pascal

    2016-08-01

    Although sensory description of wines in scientific literature is very large, there is an evident lack of studies describing wines from a dynamic approach. The objective of this study was to describe the evolution of the sensations perceived in red wines from Rioja Alavesa by using Temporal Dominance of Sensations (TDS) and also to compare wines made with the two winemaking procedures used in Rioja Alavesa: carbonic maceration (CM) and destemming (DS). Ten sensory attributes were evaluated in eight wines (four CM and four DS wines) in triplicate by a panel of 16 trained assessors. Red/black berry and woody aromas were dominant firstly, whereas heat, astringent, bitter and pungent sensations were dominant later. CM wines showed higher dominance for woody, spicy, pungent and acid sensations and lower dominance for red/black berry aroma and astringency than DS wines. This study is the first to describe Rioja wines from a dynamic approach and it also provides information about the dynamic sensory differences between wines made by CM or by DS. In this sense, this work shows the usefulness of TDS to describe and differentiate wines and to provide additional information to the conventional static descriptive analysis. © 2015 Society of Chemical Industry. © 2015 Society of Chemical Industry.

  13. Temporal condensation and dynamic λ-transition within the complex network: an application to real-life market evolution

    Science.gov (United States)

    Wiliński, Mateusz; Szewczak, Bartłomiej; Gubiec, Tomasz; Kutner, Ryszard; Struzik, Zbigniew R.

    2015-02-01

    We fill a void in merging empirical and phenomenological characterisation of the dynamical phase transitions in complex networks by identifying and thoroughly characterising a triple sequence of such transitions on a real-life financial market. We extract and interpret the empirical, numerical, and analytical evidences for the existence of these dynamical phase transitions, by considering the medium size Frankfurt stock exchange (FSE), as a typical example of a financial market. By using the canonical object for the graph theory, i.e. the minimal spanning tree (MST) network, we observe: (i) the (initial) dynamical phase transition from equilibrium to non-equilibrium nucleation phase of the MST network, occurring at some critical time. Coalescence of edges on the FSE's transient leader (defined by its largest degree) is observed within the nucleation phase; (ii) subsequent acceleration of the process of nucleation and the emergence of the condensation phase (the second dynamical phase transition), forming a logarithmically diverging temporal λ-peak of the leader's degree at the second critical time; (iii) the third dynamical fragmentation phase transition (after passing the second critical time), where the λ-peak logarithmically relaxes over three quarters of the year, resulting in a few loosely connected sub-graphs. This λ-peak (comparable to that of the specific heat vs. temperature forming during the equilibrium continuous phase transition from the normal fluid I 4He to the superfluid II 4He) is considered as a prominent result of a non-equilibrium superstar-like superhub or a dragon-king's abrupt evolution over about two and a half year of market evolution. We capture and meticulously characterise a remarkable phenomenon in which a peripheral company becomes progressively promoted to become the dragon-king strongly dominating the complex network over an exceptionally long period of time containing the crash. Detailed analysis of the complete trio of the

  14. Prediction of the Dynamic Yield Strength of Metals Using Two Structural-Temporal Parameters

    Science.gov (United States)

    Selyutina, N. S.; Petrov, Yu. V.

    2018-02-01

    The behavior of the yield strength of steel and a number of aluminum alloys is investigated in a wide range of strain rates, based on the incubation time criterion of yield and the empirical models of Johnson-Cook and Cowper-Symonds. In this paper, expressions for the parameters of the empirical models are derived through the characteristics of the incubation time criterion; a satisfactory agreement of these data and experimental results is obtained. The parameters of the empirical models can depend on some strain rate. The independence of the characteristics of the incubation time criterion of yield from the loading history and their connection with the structural and temporal features of the plastic deformation process give advantage of the approach based on the concept of incubation time with respect to empirical models and an effective and convenient equation for determining the yield strength in a wider range of strain rates.

  15. Neuronal populations in the occipital cortex of the blind synchronize to the temporal dynamics of speech

    Science.gov (United States)

    Van Ackeren, Markus Johannes; Barbero, Francesca M; Mattioni, Stefania; Bottini, Roberto

    2018-01-01

    The occipital cortex of early blind individuals (EB) activates during speech processing, challenging the notion of a hard-wired neurobiology of language. But, at what stage of speech processing do occipital regions participate in EB? Here we demonstrate that parieto-occipital regions in EB enhance their synchronization to acoustic fluctuations in human speech in the theta-range (corresponding to syllabic rate), irrespective of speech intelligibility. Crucially, enhanced synchronization to the intelligibility of speech was selectively observed in primary visual cortex in EB, suggesting that this region is at the interface between speech perception and comprehension. Moreover, EB showed overall enhanced functional connectivity between temporal and occipital cortices that are sensitive to speech intelligibility and altered directionality when compared to the sighted group. These findings suggest that the occipital cortex of the blind adopts an architecture that allows the tracking of speech material, and therefore does not fully abstract from the reorganized sensory inputs it receives. PMID:29338838

  16. Temporal and demographic blood parasite dynamics in two free-ranging neotropical primates

    Directory of Open Access Journals (Sweden)

    Gideon A. Erkenswick

    2017-08-01

    Full Text Available Parasite-host relationships are influenced by several factors intrinsic to hosts, such as social standing, group membership, sex, and age. However, in wild populations, temporal variation in parasite distributions and concomitant infections can alter these patterns. We used microscropy and molecular methods to screen for naturally occurring haemoparasitic infections in two Neotropical primate host populations, the saddleback (Leontocebus weddelli and emperor (Saguinus imperator tamarin, in the lowland tropical rainforests of southeastern Peru. Repeat sampling was conducted from known individuals over a three-year period to test for parasite-host and parasite-parasite associations. Three parasites were detected in L. weddelli including Trypanosoma minasense, Mansonella mariae, and Dipetalonema spp., while S. imperator only hosted the latter two. Temporal variation in prevalence was observed in T. minasense and Dipetalonema spp., confirming the necessity of a multi-year study to evaluate parasite-host relationships in this system. Although callitrichids display a distinct reproductive dominance hierarchy, characterized by single breeding females that typically mate polyandrously and can suppress the reproduction of subdominant females, logistic models did not identify sex or breeding status as determining factors in the presence of these parasites. However, age class had a positive effect on infection with M. mariae and T. minasense, and adults demonstrated higher parasite species richness than juveniles or sub-adults across both species. Body weight had a positive effect on the presence of Dipetalonema spp. The inclusion of co-infection variables in statistical models of parasite presence/absence data improved model fit for two of three parasites. This study verifies the importance and need for broad spectrum and long-term screening of parasite assemblages of natural host populations.

  17. Spatial and temporal consumption dynamics of trout in catch-and-release areas in Arkansas tailwaters

    Science.gov (United States)

    Flinders, John M.; Magoulick, Daniel D.

    2017-01-01

    Restrictive angling regulations in tailwater trout fisheries may be unsuccessful if food availability limits energy for fish to grow. We examined spatial and temporal variation in energy intake and growth in populations of Brown Trout Salmo trutta and Rainbow Trout Oncorhynchus mykiss within three catch-and-release (C-R) areas in Arkansas tailwaters to evaluate food availability compared with consumption. Based on bioenergetic simulations, Rainbow Trout fed at submaintenance levels in both size-classes (≤400 mm TL, >400 mm TL) throughout most seasons. A particular bottleneck in food availability occurred in the winter for Rainbow Trout when the daily ration was substantially below the minimum required for maintenance, despite reduced metabolic costs associated with lower water temperatures. Rainbow Trout growth rates followed a similar pattern to consumption with negative growth rates during the winter periods. All three size-classes (400 mm TL) of Brown Trout experienced high growth rates and limited temporal bottlenecks in food availability. We observed higher mean densities for Rainbow Trout (47–342 fish/ha) than for Brown Trout (3–84 fish/ha) in all C-R areas. Lower densities of Brown Trout coupled with an ontogenetic shift towards piscivory may have allowed for higher growth rates and sufficient consumption rates to meet energetic demands. Brown Trout at current densities were more effective in maintaining adequate growth rates and larger sizes in C-R areas than were Rainbow Trout. Bioenergetic simulations suggest that reducing stocking levels of Rainbow Trout in the tailwaters may be necessary in order to achieve increased catch rates of larger trout in the C-R areas.

  18. Dynamic profiling of different ready-to-drink fermented dairy products: A comparative study using Temporal Check-All-That-Apply (TCATA), Temporal Dominance of Sensations (TDS) and Progressive Profile (PP).

    Science.gov (United States)

    Esmerino, Erick A; Castura, John C; Ferraz, Juliana P; Tavares Filho, Elson R; Silva, Ramon; Cruz, Adriano G; Freitas, Mônica Q; Bolini, Helena M A

    2017-11-01

    Despite the several differences in ingredients, processes and nutritional values, dairy foods as yogurts, fermented milks and milk beverages are widely accepted worldwide, and although they have their sensory profiling normally covered by descriptive analyses, the temporal perception involved during the consumption are rarely considered. In this sense, the present work aimed to assess the dynamic sensory profile of three categories of fermented dairy products using different temporal methodologies: Temporal Dominance of Sensations (TDS), Progressive Profiling (PP), Temporal CATA (TCATA), and compare the results obtained. The findings showed that the different sensory characteristics among the products are basically related to their commercial identity. Regarding the methods, all of them collected the variations between samples with great correlation between data. In addition, to detect differences in intensities, TCATA showed to be the most sensitive method in detecting textural changes. When using PP, a balanced experimental design considering the number of attributes, time intervals, and food matrix must be weighed. The findings are of interest to guide sensory and consumer practitioners involved in the dairy production to formulate/reformulate their products and help them choosing the most suitable dynamic method to temporally evaluate them. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. Temporal networks

    Science.gov (United States)

    Holme, Petter; Saramäki, Jari

    2012-10-01

    A great variety of systems in nature, society and technology-from the web of sexual contacts to the Internet, from the nervous system to power grids-can be modeled as graphs of vertices coupled by edges. The network structure, describing how the graph is wired, helps us understand, predict and optimize the behavior of dynamical systems. In many cases, however, the edges are not continuously active. As an example, in networks of communication via e-mail, text messages, or phone calls, edges represent sequences of instantaneous or practically instantaneous contacts. In some cases, edges are active for non-negligible periods of time: e.g., the proximity patterns of inpatients at hospitals can be represented by a graph where an edge between two individuals is on throughout the time they are at the same ward. Like network topology, the temporal structure of edge activations can affect dynamics of systems interacting through the network, from disease contagion on the network of patients to information diffusion over an e-mail network. In this review, we present the emergent field of temporal networks, and discuss methods for analyzing topological and temporal structure and models for elucidating their relation to the behavior of dynamical systems. In the light of traditional network theory, one can see this framework as moving the information of when things happen from the dynamical system on the network, to the network itself. Since fundamental properties, such as the transitivity of edges, do not necessarily hold in temporal networks, many of these methods need to be quite different from those for static networks. The study of temporal networks is very interdisciplinary in nature. Reflecting this, even the object of study has many names-temporal graphs, evolving graphs, time-varying graphs, time-aggregated graphs, time-stamped graphs, dynamic networks, dynamic graphs, dynamical graphs, and so on. This review covers different fields where temporal graphs are considered

  20. Spatial and temporal trends and flow dynamics of glyphosate and other pesticides within an agricultural watershed in Argentina.

    Science.gov (United States)

    Pérez, Débora J; Okada, Elena; De Gerónimo, Eduardo; Menone, Mirta L; Aparicio, Virginia C; Costa, José L

    2017-12-01

    In the present study, we evaluated the spatial and temporal trends of current-use pesticides in surface water and sediments as well as their relationship with hydrological stream dynamics within the agricultural watershed of El Crespo stream (Buenos Aires Province, Argentina). We sampled 2 contrasting sites: site 1 (upstream), surrounded by agricultural lands, and site 2 (downstream), surrounded by natural grasslands. Most of the applied pesticides (glyphosate, 2,4-D, atrazine, tebuconazole, and imidacloprid) were detected at high frequencies in surface water samples at both sites. However, only glyphosate and aminomethylphosphonic acid (AMPA) were present at high concentrations and had a significant spatial-temporal trend. The highest concentrations were found during spring 2014 at site 1, in association with the intense rains that occurred in that season. The fact that glyphosate and AMPA concentrations were higher than the rest of the studied compounds is closely related to the land use within the watershed, as glyphosate was the most applied herbicide during the fallow period of glyphosate-resistant crops (soybean, maize). The pesticide mixture had a significant spatial-temporal trend, reaching the highest levels during storm flow events in spring 2014. The intensive rains in spring 2014 could be the main factor influencing stream hydrology and pesticide behavior at El Crespo watershed. The estimated annual pesticide losses were 3.11 g/ha at site 1 and 0.72 g/ha at site 2. This result indicates that an attenuation process could be decreasing pesticide loads during downstream transport from site 1 to site 2. Environ Toxicol Chem 2017;36:3206-3216. © 2017 SETAC. © 2017 SETAC.

  1. A Hybrid Approach Combining the Multi-Temporal Scale Spatio-Temporal Network with the Continuous Triangular Model for Exploring Dynamic Interactions in Movement Data: A Case Study of Football

    Directory of Open Access Journals (Sweden)

    Pengdong Zhang

    2018-01-01

    Full Text Available Benefiting from recent advantages in location-aware technologies, movement data are becoming ubiquitous. Hence, numerous research topics with respect to movement data have been undertaken. Yet, the research of dynamic interactions in movement data is still in its infancy. In this paper, we propose a hybrid approach combining the multi-temporal scale spatio-temporal network (MTSSTN and the continuous triangular model (CTM for exploring dynamic interactions in movement data. The approach mainly includes four steps: first, the relative trajectory calculus (RTC is used to derive three types of interaction patterns; second, for each interaction pattern, a corresponding MTSSTN is generated; third, for each MTSSTN, the interaction intensity measures and three centrality measures (i.e., degree, betweenness and closeness are calculated; finally, the results are visualized at multiple temporal scales using the CTM and analyzed based on the generated CTM diagrams. Based on the proposed approach, three distinctive aims can be achieved for each interaction pattern at multiple temporal scales: (1 exploring the interaction intensities between any two individuals; (2 exploring the interaction intensities among multiple individuals, and (3 exploring the importance of each individual and identifying the most important individuals. The movement data obtained from a real football match are used as a case study to validate the effectiveness of the proposed approach. The results demonstrate that the proposed approach is useful in exploring dynamic interactions in football movement data and discovering insightful information.

  2. Culicidae community composition and temporal dynamics in Guapiaçu Ecological Reserve, Cachoeiras de Macacu, Rio de Janeiro, Brazil.

    Directory of Open Access Journals (Sweden)

    Jeronimo Alencar

    Full Text Available A temporal observational study was conducted of the Culicidae fauna in a remnant area of Atlantic Forest within a private reserve (Guapiaçu Ecological Reserve-REGUA presenting typical vegetation cover of dense rain forest, with some patches recovering a floristic composition similar to that of the original community. Research was carried out to analyze the influence of climatic factors (mean monthly temperature, rainfall, and air relative humidity on the temporal dynamics of the mosquito communities that occur in the reserve. The completeness of the mosquito inventory was assessed with individual-based rarefaction-extrapolation curves. Differences in species composition between sites and months were tested with PERMANOVA. True diversities of orders 0, 1, and 2 (effective numbers were estimated and compared between sites, months, and years. Multiple stepwise regressions were used to assess relationships between climatic variables, measures of diversity, and abundances of the most common species. There were significant interactive effects between year and site on measures of diversity. However, diversity estimates showed little variation among months, and these were weakly correlated with climatic variables. Abundances of the most common species were significantly related to temperature or relative humidity, but not rainfall. The presence of mosquito species known to be vectors of human diseases combined with an intermittent flow of visitors to the study area suggests there is a risk of disease transmission that warrants further monitoring.

  3. Culicidae Community Composition and Temporal Dynamics in Guapiaçu Ecological Reserve, Cachoeiras de Macacu, Rio de Janeiro, Brazil

    Science.gov (United States)

    Alencar, Jeronimo; de Mello, Cecilia Ferreira; Guimarães, Anthony Érico; Gil-Santana, Hélcio R.; Silva, Júlia dos Santos; Santos- Mallet, Jacenir R.; Gleiser, Raquel M.

    2015-01-01

    A temporal observational study was conducted of the Culicidae fauna in a remnant area of Atlantic Forest within a private reserve (Guapiaçu Ecological Reserve-REGUA) presenting typical vegetation cover of dense rain forest, with some patches recovering a floristic composition similar to that of the original community. Research was carried out to analyze the influence of climatic factors (mean monthly temperature, rainfall, and air relative humidity) on the temporal dynamics of the mosquito communities that occur in the reserve. The completeness of the mosquito inventory was assessed with individual-based rarefaction-extrapolation curves. Differences in species composition between sites and months were tested with PERMANOVA. True diversities of orders 0, 1, and 2 (effective numbers) were estimated and compared between sites, months, and years. Multiple stepwise regressions were used to assess relationships between climatic variables, measures of diversity, and abundances of the most common species. There were significant interactive effects between year and site on measures of diversity. However, diversity estimates showed little variation among months, and these were weakly correlated with climatic variables. Abundances of the most common species were significantly related to temperature or relative humidity, but not rainfall. The presence of mosquito species known to be vectors of human diseases combined with an intermittent flow of visitors to the study area suggests there is a risk of disease transmission that warrants further monitoring. PMID:25815724

  4. Spatial and temporal dynamics of mass mortalities in oysters is influenced by energetic reserves and food quality.

    Science.gov (United States)

    Pernet, Fabrice; Lagarde, Franck; Jeannée, Nicolas; Daigle, Gaetan; Barret, Jean; Le Gall, Patrik; Quere, Claudie; D'orbcastel, Emmanuelle Roque

    2014-01-01

    Although spatial studies of diseases on land have a long history, far fewer have been made on aquatic diseases. Here, we present the first large-scale, high-resolution spatial and temporal representation of a mass mortality phenomenon cause by the Ostreid herpesvirus (OsHV-1) that has affected oysters (Crassostrea gigas) every year since 2008, in relation to their energetic reserves and the quality of their food. Disease mortality was investigated in healthy oysters deployed at 106 locations in the Thau Mediterranean lagoon before the start of the epizootic in spring 2011. We found that disease mortality of oysters showed strong spatial dependence clearly reflecting the epizootic process of local transmission. Disease initiated inside oyster farms spread rapidly beyond these areas. Local differences in energetic condition of oysters, partly driven by variation in food quality, played a significant role in the spatial and temporal dynamics of disease mortality. In particular, the relative contribution of diatoms to the diet of oysters was positively correlated with their energetic reserves, which in turn decreased the risk of disease mortality.

  5. Spatial and Temporal Dynamics of Mass Mortalities in Oysters Is Influenced by Energetic Reserves and Food Quality

    Science.gov (United States)

    Pernet, Fabrice; Lagarde, Franck; Jeannée, Nicolas; Daigle, Gaetan; Barret, Jean; Le Gall, Patrik; Quere, Claudie; D’orbcastel, Emmanuelle Roque

    2014-01-01

    Although spatial studies of diseases on land have a long history, far fewer have been made on aquatic diseases. Here, we present the first large-scale, high-resolution spatial and temporal representation of a mass mortality phenomenon cause by the Ostreid herpesvirus (OsHV-1) that has affected oysters (Crassostrea gigas) every year since 2008, in relation to their energetic reserves and the quality of their food. Disease mortality was investigated in healthy oysters deployed at 106 locations in the Thau Mediterranean lagoon before the start of the epizootic in spring 2011. We found that disease mortality of oysters showed strong spatial dependence clearly reflecting the epizootic process of local transmission. Disease initiated inside oyster farms spread rapidly beyond these areas. Local differences in energetic condition of oysters, partly driven by variation in food quality, played a significant role in the spatial and temporal dynamics of disease mortality. In particular, the relative contribution of diatoms to the diet of oysters was positively correlated with their energetic reserves, which in turn decreased the risk of disease mortality. PMID:24551106

  6. Spatial and temporal dynamics of mass mortalities in oysters is influenced by energetic reserves and food quality.

    Directory of Open Access Journals (Sweden)

    Fabrice Pernet

    Full Text Available Although spatial studies of diseases on land have a long history, far fewer have been made on aquatic diseases. Here, we present the first large-scale, high-resolution spatial and temporal representation of a mass mortality phenomenon cause by the Ostreid herpesvirus (OsHV-1 that has affected oysters (Crassostrea gigas every year since 2008, in relation to their energetic reserves and the quality of their food. Disease mortality was investigated in healthy oysters deployed at 106 locations in the Thau Mediterranean lagoon before the start of the epizootic in spring 2011. We found that disease mortality of oysters showed strong spatial dependence clearly reflecting the epizootic process of local transmission. Disease initiated inside oyster farms spread rapidly beyond these areas. Local differences in energetic condition of oysters, partly driven by variation in food quality, played a significant role in the spatial and temporal dynamics of disease mortality. In particular, the relative contribution of diatoms to the diet of oysters was positively correlated with their energetic reserves, which in turn decreased the risk of disease mortality.

  7. Simultaneous application of multiple platforms (Glider, Scanfish, profiling mooring, CTD) to improve detection and quantification of temporal ocean dynamics

    Science.gov (United States)

    Meyer, D.; Prien, R. D.; Lips, U.; Naumann, M.; Liblik, T.; Schulz-Bull, D. E.

    2016-02-01

    Ocean dynamics are difficult to observe given the broad spectrum of temporal and spatial scales. Robotic technology can be used to address this issue, and help to investigate the variability of physical and biogeochemical processes. This work focuses on ocean robots and in particular on glider technology which seems to be one of the most promising oceanographic tools for future marine research. In this context, we present the results of an observational program conducted in the Baltic Sea combining a profiling mooring (GODESS - Gotland Deep Environmental Sampling Station) and glider technology (Slocum). The temporal variability is captured by the mooring, while the spatial variability is obtained from the glider sampling the surrounding area. Furthermore, classical CTD-measurements and an underwater vehicle (Scanfish) are used simultaneously by two different research vessels to validate and complement the observing network. The main aim of the study is to identify possible synergies between the different platforms and to get a better understanding of maximizing the information content of the data collected by this network. The value and the quality of the data of each individual platform is analyzed and their contribution to the performance of the network itself evaluated.

  8. The Dynamics and Neural Correlates of Audio-Visual Integration Capacity as Determined by Temporal Unpredictability, Proactive Interference, and SOA.

    Directory of Open Access Journals (Sweden)

    Jonathan M P Wilbiks

    Full Text Available Over 5 experiments, we challenge the idea that the capacity of audio-visual integration need be fixed at 1 item. We observe that the conditions under which audio-visual integration is most likely to exceed 1 occur when stimulus change operates at a slow rather than fast rate of presentation and when the task is of intermediate difficulty such as when low levels of proactive interference (3 rather than 8 interfering visual presentations are combined with the temporal unpredictability of the critical frame (Experiment 2, or, high levels of proactive interference are combined with the temporal predictability of the critical frame (Experiment 4. Neural data suggest that capacity might also be determined by the quality of perceptual information entering working memory. Experiment 5 supported the proposition that audio-visual integration was at play during the previous experiments. The data are consistent with the dynamic nature usually associated with cross-modal binding, and while audio-visual integration capacity likely cannot exceed uni-modal capacity estimates, performance may be better than being able to associate only one visual stimulus with one auditory stimulus.

  9. The Dynamics and Neural Correlates of Audio-Visual Integration Capacity as Determined by Temporal Unpredictability, Proactive Interference, and SOA.

    Science.gov (United States)

    Wilbiks, Jonathan M P; Dyson, Benjamin J

    2016-01-01

    Over 5 experiments, we challenge the idea that the capacity of audio-visual integration need be fixed at 1 item. We observe that the conditions under which audio-visual integration is most likely to exceed 1 occur when stimulus change operates at a slow rather than fast rate of presentation and when the task is of intermediate difficulty such as when low levels of proactive interference (3 rather than 8 interfering visual presentations) are combined with the temporal unpredictability of the critical frame (Experiment 2), or, high levels of proactive interference are combined with the temporal predictability of the critical frame (Experiment 4). Neural data suggest that capacity might also be determined by the quality of perceptual information entering working memory. Experiment 5 supported the proposition that audio-visual integration was at play during the previous experiments. The data are consistent with the dynamic nature usually associated with cross-modal binding, and while audio-visual integration capacity likely cannot exceed uni-modal capacity estimates, performance may be better than being able to associate only one visual stimulus with one auditory stimulus.

  10. The relationship between employees' perceptions of human resource systems and organizational performance: examining mediating mechanisms and temporal dynamics.

    Science.gov (United States)

    Piening, Erk P; Baluch, Alina M; Salge, Torsten Oliver

    2013-11-01

    Given the limited understanding of temporal issues in extant theorizing about the link between human resource management (HRM) and performance, in this study we aim to shed light on how, when, and why HR interventions affect organizational performance. On the basis of longitudinal, multi-informant and multisource data from public hospital services in England, we provide new insights into the complex interplay between employees' perceptions of HR systems, job satisfaction, and performance outcomes over time. The dynamic panel data analyses provide support for changes in employees' experience of an HR system being related to subsequent changes in customer satisfaction, as mediated by changes in job satisfaction, albeit these effects decrease over time. Moreover, our longitudinal analyses highlight the importance of feedback effects in the HRM-performance chain, which otherwise appears to evolve in a cyclical manner. (c) 2013 APA, all rights reserved.

  11. Glutamate metabolism in temporal lobe epilepsy as revealed by dynamic proton MRS following the infusion of [U13-C] glucose.

    Science.gov (United States)

    Bartnik-Olson, Brenda L; Ding, Daniel; Howe, John; Shah, Amul; Losey, Travis

    2017-10-01

    Focal metabolic dysfunction commonly observed in temporal lobe epilepsy (TLE), and is associated with the development of medical intractability and neurocognitive deficits. It has not been established if this dysfunction is due to cell loss or biochemical dysfunction in metabolic pathways. To explore this question, dynamic 1 H MRS following an infusion of [U 13 - C] glucose was performed to measure glutamate (Glu) metabolism. Subjects (n=6) showed reduced Glu levels (ptemporal lobe (MTL) compared with controls (n=4). However, the rate of 13 C incorporation into Glu did not differ between those with epilepsy and controls (p=0.77). This suggests that reduced Glu concentrations in the region of the seizure focus are not due to disruptions in metabolic pathways, but may instead be due to neuronal loss or simplification. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Rhythm and Time in Music Epitomize the Temporal Dynamics of Human Communicative Behavior: The Broad Implications of London's Trinity

    Directory of Open Access Journals (Sweden)

    Peter E. Keller

    2012-09-01

    Full Text Available Three key issues about rhythm and timing in music are drawn to the attention of linguists in a paper by London (2012. In this commentary, I argue that these issues are relevant not only to linguists, but also to those in any field dealing with the temporal dynamics of human communicative behavior. Thus, the distinction between endogenously and exogenously driven mechanisms of perceptual organization, the active nature of perception, and the presence of multiple time scales are topics that also concern experimental psychologists and cognitive neuroscientists. London’s argument that these three issues play a crucial role in the perception of rhythm and timing implies that they should be considered collectively when attempting to understand diverse communicative acts.

  13. Emotion regulation and the temporal dynamics of emotions: Effects of cognitive reappraisal and expressive suppression on emotional inertia.

    Science.gov (United States)

    Koval, Peter; Butler, Emily A; Hollenstein, Tom; Lanteigne, Dianna; Kuppens, Peter

    2015-01-01

    The tendency for emotions to be predictable over time, labelled emotional inertia, has been linked to low well-being and is thought to reflect impaired emotion regulation. However, almost no studies have examined how emotion regulation relates to emotional inertia. We examined the effects of cognitive reappraisal and expressive suppression on the inertia of behavioural, subjective and physiological measures of emotion. In Study 1 (N = 111), trait suppression was associated with higher inertia of negative behaviours. We replicated this finding experimentally in Study 2 (N = 186). Furthermore, in Study 2, instructed suppressors and reappraisers both showed higher inertia of positive behaviours, and reappraisers displayed higher inertia of heart rate. Neither suppression nor reappraisal were associated with the inertia of subjective feelings in either study. Thus, the effects of suppression and reappraisal on the temporal dynamics of emotions depend on the valence and emotional response component in question.

  14. Complete mitochondrial genome sequences of Korean native horse from Jeju Island: uncovering the spatio-temporal dynamics.

    Science.gov (United States)

    Yoon, Sook Hee; Kim, Jaemin; Shin, Donghyun; Cho, Seoae; Kwak, Woori; Lee, Hak-Kyo; Park, Kyoung-Do; Kim, Heebal

    2017-04-01

    The Korean native horse (Jeju horse) is one of the most important animals in Korean historical, cultural, and economical viewpoints. In the early 1980s, the Jeju horse was close to extinction. The aim of this study is to explore the phylogenomics of Korean native horse focusing on spatio-temporal dynamics. We determined complete mitochondrial genome sequences for the first Korean native (n = 6) and additional Mongolian (n = 2) horses. Those sequences were analyzed together with 143 published ones using Bayesian coalescent approach as well as three different phylogenetic analysis methods, Bayesian inference, maximum likelihood, and neighbor-joining methods. The phylogenomic trees revealed that the Korean native horses had multiple origins and clustered together with some horses from four European and one Middle Eastern breeds. Our phylogenomic analyses also supported that there was no apparent association between breed or geographic location and the evolution of global horses. Time of the most recent common ancestor of the Korean native horse was approximately 13,200-63,200 years, which was much younger than 0.696 My of modern horses. Additionally, our results showed that all global horse lineages including Korean native horse existed prior to their domestication events occurred in about 6000-10,000 years ago. This is the first study on phylogenomics of the Korean native horse focusing on spatio-temporal dynamics. Our findings increase our understanding of the domestication history of the Korean native horses, and could provide useful information for horse conservation projects as well as for horse genomics, emergence, and the geographical distribution.

  15. Spatio-temporal dynamics of ocean conditions and forage taxa reveal regional structuring of seabird–prey relationships.

    Science.gov (United States)

    Santora, Jarrod A; Schroeder, Isaac D; Field, John C; Wells, Brian K; Sydeman, William J

    Studies of predator–prey demographic responses and the physical drivers of such relationships are rare, yet essential for predicting future changes in the structure and dynamics of marine ecosystems. Here, we hypothesize that predator–prey relationships vary spatially in association with underlying physical ocean conditions, leading to observable changes in demographic rates, such as reproduction. To test this hypothesis, we quantified spatio-temporal variability in hydrographic conditions, krill, and forage fish to model predator (seabird) demographic responses over 18 years (1990–2007). We used principal component analysis and spatial correlation maps to assess coherence among ocean conditions, krill, and forage fish, and generalized additive models to quantify interannual variability in seabird breeding success relative to prey abundance. The first principal component of four hydrographic measurements yielded an index that partitioned “warm/weak upwelling” and “cool/strong upwelling” years. Partitioning of krill and forage fish time series among shelf and oceanic regions yielded spatially explicit indicators of prey availability. Krill abundance within the oceanic region was remarkably consistent between years, whereas krill over the shelf showed marked interannual fluctuations in relation to ocean conditions. Anchovy abundance varied on the shelf, and was greater in years of strong stratification, weak upwelling and warmer temperatures. Spatio-temporal variability of juvenile forage fish co-varied strongly with each other and with krill, but was weakly correlated with hydrographic conditions. Demographic responses between seabirds and prey availability revealed spatially variable associations indicative of the dynamic nature of “predator–habitat” relationships. Quantification of spatially explicit demographic responses, and their variability through time, demonstrate the possibility of delineating specific critical areas where the

  16. Dynamic analysis of temporal moisture profiles in heatset printing studied with near-infrared spectroscopy

    International Nuclear Information System (INIS)

    Tåg, C-M; Toiviainen, M; Juuti, M; Gane, P A C

    2010-01-01

    Dynamic analysis of the water transfer onto coated paper, and its permeation and absorption into the porous structure were studied online in a full-scale heatset web offset printing environment. The moisture content of the paper was investigated at five different positions during the printing process. Changes in the moisture content of the paper were studied as a function of the web temperature, printing speed and silicone application in the folding unit positioned after the hot air drying oven. Additionally, the influence of fountain solution composition on the pick-up by the paper was investigated. The water content of the fountain solution transferred to the paper from the printing units was observed as changes in near-infrared absorbance. A calibration data set enabled the subsequent quantification of the dynamic moisture content of the paper at the studied locations. An increase in the printing speed reduced the water transfer to the paper and an increase in web temperature resulted in a reduction in the moisture content. An increase in the dosage level of the water–silicone mixture was observed as a re-moistening effect of the paper. Differences in the drying strategy resulted in different moisture profiles depending on the type of fountain solution used. As a conclusion, the near-infrared signal provides an effective way to characterize the moisture dynamics online at different press units

  17. Fire in Fennoscandia: A palaeo-perspective of spatial and temporal variability in fire frequency and vegetation dynamics

    Science.gov (United States)

    Clear, Jennifer; Bradshaw, Richard; Seppä, Heikki

    2014-05-01

    Active fire suppression in Fennoscandia has created a boreal forest ecosystem that is almost free of fire. Absence of fire is thought to have contributed to the widespread dominance of Picea abies (Norway spruce), though the character and structure of spruce forests operates as a positive feedback retarding fire frequency. This lack of fire and dominance by Picea abies may have assisted declines in deciduous tree species, with a concomitant loss of floristic diversity. Forest fires are driven by a complex interplay between natural (climate, vegetation and topography) and anthropogenic disturbance and through palaeoecology we are able to explore spatio-temporal variability in the drivers of fire, changing fire dynamics and the subsequent consequences for forest succession, development and floristic diversity over long timescales. High resolution analysis of palaeoenvironmental proxies (pollen and macroscopic charcoal) allows Holocene vegetation and fire dynamics to be reconstructed at the local forest-stand scale. Comparisons of fire histories with pollen-derived quantitative reconstruction of vegetation at local- and regional-scales identify large-scale ecosystem responses and local-scale disturbance. Spatio-temporal heterogeneity and variability in biomass burning is explored to identify the drivers of fire and palaeovegetation reconstructions are compared to process-based, climate-driven dynamic vegetation model output to test the significance of fire frequency as a driver of vegetation composition and dynamics. Fire was not always so infrequent in the northern European forest with early-Holocene fire regimes driven by natural climate variations and fuel availability. The establishment and spread of Picea abies was probably driven by an increase in continentality of climate, but local natural and anthropogenic ecosystem disturbance may have aided this spread. Picea expansion led to a step-wise reduction in regional biomass burning and here we show the now

  18. Improved accuracy of quantitative parameter estimates in dynamic contrast-enhanced CT study with low temporal resolution

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Sun Mo, E-mail: Sunmo.Kim@rmp.uhn.on.ca [Radiation Medicine Program, Princess Margaret Hospital/University Health Network, Toronto, Ontario M5G 2M9 (Canada); Haider, Masoom A. [Department of Medical Imaging, Sunnybrook Health Sciences Centre, Toronto, Ontario M4N 3M5, Canada and Department of Medical Imaging, University of Toronto, Toronto, Ontario M5G 2M9 (Canada); Jaffray, David A. [Radiation Medicine Program, Princess Margaret Hospital/University Health Network, Toronto, Ontario M5G 2M9, Canada and Department of Radiation Oncology, University of Toronto, Toronto, Ontario M5G 2M9 (Canada); Yeung, Ivan W. T. [Radiation Medicine Program, Princess Margaret Hospital/University Health Network, Toronto, Ontario M5G 2M9 (Canada); Department of Medical Physics, Stronach Regional Cancer Centre, Southlake Regional Health Centre, Newmarket, Ontario L3Y 2P9 (Canada); Department of Radiation Oncology, University of Toronto, Toronto, Ontario M5G 2M9 (Canada)

    2016-01-15

    Purpose: A previously proposed method to reduce radiation dose to patient in dynamic contrast-enhanced (DCE) CT is enhanced by principal component analysis (PCA) filtering which improves the signal-to-noise ratio (SNR) of time-concentration curves in the DCE-CT study. The efficacy of the combined method to maintain the accuracy of kinetic parameter estimates at low temporal resolution is investigated with pixel-by-pixel kinetic analysis of DCE-CT data. Methods: The method is based on DCE-CT scanning performed with low temporal resolution to reduce the radiation dose to the patient. The arterial input function (AIF) with high temporal resolution can be generated with a coarsely sampled AIF through a previously published method of AIF estimation. To increase the SNR of time-concentration curves (tissue curves), first, a region-of-interest is segmented into squares composed of 3 × 3 pixels in size. Subsequently, the PCA filtering combined with a fraction of residual information criterion is applied to all the segmented squares for further improvement of their SNRs. The proposed method was applied to each DCE-CT data set of a cohort of 14 patients at varying levels of down-sampling. The kinetic analyses using the modified Tofts’ model and singular value decomposition method, then, were carried out for each of the down-sampling schemes between the intervals from 2 to 15 s. The results were compared with analyses done with the measured data in high temporal resolution (i.e., original scanning frequency) as the reference. Results: The patients’ AIFs were estimated to high accuracy based on the 11 orthonormal bases of arterial impulse responses established in the previous paper. In addition, noise in the images was effectively reduced by using five principal components of the tissue curves for filtering. Kinetic analyses using the proposed method showed superior results compared to those with down-sampling alone; they were able to maintain the accuracy in the

  19. Dynamic changes during evacuation of a left temporal abscess in open MRI: technical case report

    Energy Technology Data Exchange (ETDEWEB)

    Bernays, R.L.; Yonekawa, Y. [Department of Neurosurgery, University Hospital, Zurich (Switzerland); Kollias, S.S. [Institute of Neuroradiology, University Hospital of Zurich (Switzerland)

    2002-05-01

    We demonstrate the usefulness of ''near real-time'' neuro-navigation by open MRI systems for guidance of stereotactic evacuation of intracranial abscesses. A 70-year-old patient was referred to our institution with an intracranial left temporal abscess. He presented with headache, senso-motor aphasia and mild right hemiparesis. The abscess (35 x 25 mm) was stereotactically evacuated under MRI guidance, and a recurrence of a daughter abscess was again evacuated on the 9th postoperative day. ''Near real-time'' imaging showed an indentation of the abscess wall of 11 mm along the trajectory. A thermosensitive MRI protocol demonstrated a higher temperature around the abscess capsule than in the brain tissue more distant to the capsule, demonstrating the inflammatory process. The patient had 6 weeks of antibiotic therapy for gram-negative bacteria and was discharged with improved clinical symptoms 5 weeks after admission. Follow-up CT 2 months postoperatively showed a complete resolution of the abscess. Open MRI-guided interventions with ''near real-time'' imaging demonstrate the anatomical changes during an ongoing procedure and can be accommodated for enhancing the overall precision of stereotactic procedures. Thermosensitive MRI protocols are capable of revealing temperature gradients around inflammatory processes. (orig.)

  20. The Dynamic contribution of chronic conditions to temporal trends in disability among U.S. adults.

    Science.gov (United States)

    Lin, Shih-Fan; Beck, Audrey N; Finch, Brian K

    2016-04-01

    Although evidence has shown that U.S. late-life disability has been declining, studies have also suggested that there has been an increase in chronic diseases between 1984 and 2007. To further illuminate these potentially contradictory trends, we explicate how the contribution of chronic conditions changes across four common types of disability (ADL, IADL, mobility disability, and functional limitations) by age (A), period (P), and birth cohorts (C) among adults aged 20 and above. Our data came from seven cross-sectional waves of the National Health and Nutrition Examination Survey (NHANES). We utilize a cross-classified random effect model (CCREM) to simultaneously estimate age, period, and cohort trends for each disability. Each chronic condition was sequentially then simultaneously added to our base models (sociodemographics only). Reductions in predicted probability from the base model were then calculated for each chronic condition by each temporal dimension (A/P/C) to assess the contribution of each chronic condition. There was increasing age-based contribution of chronic conditions to all disabilities. The period-based contribution remained quite stagnant across years while cohort-based contributions showed a continual decline for recent cohorts. Arthritis showed the greatest contribution to disability of all types which was followed by obesity. Cancer was the least important contributor to disabilities. Although chronic conditions are becoming less disabling across recent cohorts, other competing risk factors might suggest prevailing causes of disability. Copyright © 2016 Elsevier Inc. All rights reserved.

  1. Spatio-Temporal Dynamic Analysis of Sustainable Development in China Based on the Footprint Family

    Science.gov (United States)

    Ma, Caihong; Zhao, Xiangui; Wang, Xiaoyu

    2018-01-01

    The existing index systems on sustainable evaluation are mostly based on a multi index comprehensive evaluation method. The main disadvantage of this approach is that the selection and assignment of evaluation indexes are greatly influenced by subjective factors, which can result in poor comparability of results. By contrast, the Footprint Family (including ecological footprint, carbon footprint, and water footprint) is not affected by subjective factors. The Footprint Family also covers the basic tenets of sustainable development. This paper proposes use of a sustainable development evaluation index system based on the principle of the Footprint Family, and including the ecological pressure index (EPI), the ecological occupancy index (EOI), the ecological economic coordination index (EECI), the GHG (Greenhouse Gas) emission index (CEI), the water resources stress index (WSI), and the sustainable development index (SDI). Furthermore, a standard for grading the evaluated results based on global benchmarks is formulated. The results of an empirical study in China were the following. The development situation deteriorated from 1990 to 2015. The results showed that the SDI decreased from a medium level (grade 5) to a lower-medium level (grade 4). The results of this empirical study also showed that the method of evaluation can avoid the influence of subjective factors and can be used in the evaluation of sustainable development for various temporal and spatial conditions. PMID:29389886

  2. Temporal Dynamics of Task Switching and Abstract-Concept Learning in Pigeons

    Directory of Open Access Journals (Sweden)

    Thomas Alexander Daniel

    2015-09-01

    Full Text Available The current study examined whether pigeons could learn to use abstract concepts as the basis for conditionally switching behavior as a function of time. Using a mid-session reversal task, experienced pigeons were trained to switch from matching-to-sample (MTS to non-matching-to-sample (NMTS conditional discriminations within a session. One group had prior training with MTS, while the other had prior training with NMTS. Over training, stimulus set size was progressively doubled from 3 to 6 to 12 stimuli to promote abstract concept development. Prior experience had an effect on the initial learning at each of the set sizes but by the end of training there were no group differences, as both groups showed similar within-session linear matching functions. After acquiring the 12-item set, abstract-concept learning was tested by placing novel stimuli at the beginning and end of a test session. Prior matching and non-matching experience affected transfer behavior. The matching experienced group transferred to novel stimuli in both the matching and non-matching portion of the sessions using a matching rule. The non-matching experienced group transferred to novel stimuli in both portions of the session using a non-matching rule. The representations used as the basis for mid-session reversal of the conditional discrimination behaviors and subsequent transfer behavior appears to have different temporal sources. The implications for the flexibility and organization of complex behaviors are considered.

  3. Spatio-temporal dynamics of tularemia in French wildlife: 2002-2013.

    Science.gov (United States)

    Moinet, Marie; Decors, Anouk; Mendy, Christiane; Faure, Eva; Durand, Benoit; Madani, Nora

    2016-08-01

    Tularemia, caused by Francisella tularensis, is endemic in France. The surveillance of this disease in wildlife is operated by the SAGIR Network and by the National Reference Laboratory for Tularemia. Wild animals found dead or dying collected by the SAGIR network are necropsied and when tularemia is suspected culture and/or PCR are performed to confirm the diagnosis. The aim of this study was to present the results of tularemia surveillance in wildlife and to investigate the spatial and temporal pattern of tularemia observed between the 2002-2003 and 2012-2013 hunting seasons in French wildlife. Fourty-one to 121 cases were collected each hunting season for a total of 693 confirmed cases and 46 additional suspected cases. The main species affected was the European Brown Hare (Lepus europaeus) but 4 rabbits (Oryctolagus cuniculus), 2 roe deer (Capreolus capreolus) and one wild boar (Sus scrofa) were also found positive. The Standard Mortality Ratio was mapped and Kulldorff's retrospective space-time scan statistic was implemented and allowed the detection of several clusters: the nationwide outbreak of 2007-2008; 2 clusters in northern and central-western France in high hare-abundance areas and another in North-eastern France where the abundance of hares is low. Our results confirm the usefulness of brown hare as a sentinel of environmental risk. Copyright © 2016 Elsevier B.V. All rights reserved.

  4. Vertical and temporal dynamics of cyanobacteria in the Carpina potable water reservoir in northeastern Brazil.

    Science.gov (United States)

    Moura, A N; Dantas, E W; Oliveira, H S B; Bittencourt-Oliveira, M C

    2011-05-01

    This study analysed vertical and temporal variations of cyanobacteria in a potable water supply in northeastern Brazil. Samples were collected from four reservoir depths in the four months; September and December 2007; and March and June 2008. The water samples for the determination of nutrients and cyanobacteria were collected using a horizontal van Dorn bottle. The samples were preserved in 4% formaldehyde for taxonomic analysis using an optical microscope, and water aliquots were preserved in acetic Lugol solution for determination of density using an inverted microscope. High water temperatures, alkaline pH, low transparency, high phosphorous content and limited nitrogen content were found throughout the study. Dissolved oxygen stratification occurred throughout the study period whereas temperature stratification occurred in all sampling months, with the exception of June. No significant vertical differences were recorded for turbidity or total and dissolved forms of nutrients. There were high levels of biomass arising from Planktothrix agardhii, Cylindrospermopsis raciborskii, Geitlerinema amphibium and Pseudanabaena catenata. The study demonstrates that, in a tropical eutrophic environment with high temperatures throughout the water column, perennial multi-species cyanobacterial blooms, formed by species capable of regulating their position in the water column (those that have gas vesicles for buoyancy), are dominant in the photic and aphotic strata.

  5. Vertical and temporal dynamics of cyanobacteria in the Carpina potable water reservoir in northeastern Brazil

    Directory of Open Access Journals (Sweden)

    AN Moura

    Full Text Available This study analysed vertical and temporal variations of cyanobacteria in a potable water supply in northeastern Brazil. Samples were collected from four reservoir depths in the four months; September and December 2007; and March and June 2008. The water samples for the determination of nutrients and cyanobacteria were collected using a horizontal van Dorn bottle. The samples were preserved in 4% formaldehyde for taxonomic analysis using an optical microscope, and water aliquots were preserved in acetic Lugol solution for determination of density using an inverted microscope. High water temperatures, alkaline pH, low transparency, high phosphorous content and limited nitrogen content were found throughout the study. Dissolved oxygen stratification occurred throughout the study period whereas temperature stratification occurred in all sampling months, with the exception of June. No significant vertical differences were recorded for turbidity or total and dissolved forms of nutrients. There were high levels of biomass arising from Planktothrix agardhii, Cylindrospermopsis raciborskii, Geitlerinema amphibium and Pseudanabaena catenata. The study demonstrates that, in a tropical eutrophic environment with high temperatures throughout the water column, perennial multi-species cyanobacterial blooms, formed by species capable of regulating their position in the water column (those that have gas vesicles for buoyancy, are dominant in the photic and aphotic strata.

  6. Plant reproductive allocation predicts herbivore dynamics across spatial and temporal scales.

    Science.gov (United States)

    Miller, Tom E X; Tyre, Andrew J; Louda, Svata M

    2006-11-01

    Life-history theory suggests that iteroparous plants should be flexible in their allocation of resources toward growth and reproduction. Such plasticity could have consequences for herbivores that prefer or specialize on vegetative versus reproductive structures. To test this prediction, we studied the response of the cactus bug (Narnia pallidicornis) to meristem allocation by tree cholla cactus (Opuntia imbricata). We evaluated the explanatory power of demographic models that incorporated variation in cactus relative reproductive effort (RRE; the proportion of meristems allocated toward reproduction). Field data provided strong support for a single model that defined herbivore fecundity as a time-varying, increasing function of host RRE. High-RRE plants were predicted to support larger insect populations, and this effect was strongest late in the season. Independent field data provided strong support for these qualitative predictions and suggested that plant allocation effects extend across temporal and spatial scales. Specifically, late-season insect abundance was positively associated with interannual changes in cactus RRE over 3 years. Spatial variation in insect abundance was correlated with variation in RRE among five cactus populations across New Mexico. We conclude that plant allocation can be a critical component of resource quality for insect herbivores and, thus, an important mechanism underlying variation in herbivore abundance across time and space.

  7. Analysis of temporal dynamics in imagery during acute limb ischemia and reperfusion

    Science.gov (United States)

    Irvine, John M.; Regan, John; Spain, Tammy A.; Caruso, Joseph D.; Rodriquez, Maricela; Luthra, Rajiv; Forsberg, Jonathon; Crane, Nicole J.; Elster, Eric

    2014-03-01

    Ischemia and reperfusion injuries present major challenges for both military and civilian medicine. Improved methods for assessing the effects and predicting outcome could guide treatment decisions. Specific issues related to ischemia and reperfusion injury can include complications arising from tourniquet use, such as microvascular leakage in the limb, loss of muscle strength and systemic failures leading to hypotension and cardiac failure. Better methods for assessing the viability of limbs/tissues during ischemia and reducing complications arising from reperfusion are critical to improving clinical outcomes for at-risk patients. The purpose of this research is to develop and assess possible prediction models of outcome for acute limb ischemia using a pre-clinical model. Our model relies only on non-invasive imaging data acquired from an animal study. Outcome is measured by pathology and functional scores. We explore color, texture, and temporal features derived from both color and thermal motion imagery acquired during ischemia and reperfusion. The imagery features form the explanatory variables in a model for predicting outcome. Comparing model performance to outcome prediction based on direct observation of blood chemistry, blood gas, urinalysis, and physiological measurements provides a reference standard. Initial results show excellent performance for the imagery-base model, compared to predictions based direct measurements. This paper will present the models and supporting analysis, followed by recommendations for future investigations.

  8. A Model of the Spatio-temporal Dynamics of Drosophila Eye Disc Development.

    Science.gov (United States)

    Fried, Patrick; Sánchez-Aragón, Máximo; Aguilar-Hidalgo, Daniel; Lehtinen, Birgitta; Casares, Fernando; Iber, Dagmar

    2016-09-01

    Patterning and growth are linked during early development and have to be tightly controlled to result in a functional tissue or organ. During the development of the Drosophila eye, this linkage is particularly clear: the growth of the eye primordium mainly results from proliferating cells ahead of the morphogenetic furrow (MF), a moving signaling wave that sweeps across the tissue from the posterior to the anterior side, that induces proliferating cells anterior to it to differentiate and become cell cycle quiescent in its wake. Therefore, final eye disc size depends on the proliferation rate of undifferentiated cells and on the speed with which the MF sweeps across the eye disc. We developed a spatio-temporal model of the growing eye disc based on the regulatory interactions controlled by the signals Decapentaplegic (Dpp), Hedgehog (Hh) and the transcription factor Homothorax (Hth) and explored how the signaling patterns affect the movement of the MF and impact on eye disc growth. We used published and new quantitative data to parameterize the model. In particular, two crucial parameter values, the degradation rate of Hth and the diffusion coefficient of Hh, were measured. The model is able to reproduce the linear movement of the MF and the termination of growth of the primordium. We further show that the model can explain several mutant phenotypes, but fails to reproduce the previously observed scaling of the Dpp gradient in the anterior compartment.

  9. Temporal and spatial transcriptomic and microRNA dynamics of CAM photosynthesis in pineapple.

    Science.gov (United States)

    Wai, Ching M; VanBuren, Robert; Zhang, Jisen; Huang, Lixian; Miao, Wenjing; Edger, Patrick P; Yim, Won C; Priest, Henry D; Meyers, Blake C; Mockler, Todd; Smith, J Andrew C; Cushman, John C; Ming, Ray

    2017-10-01

    The altered carbon assimilation pathway of crassulacean acid metabolism (CAM) photosynthesis results in an up to 80% higher water-use efficiency than C 3 photosynthesis in plants making it a potentially useful pathway for engineering crop plants with improved drought tolerance. Here we surveyed detailed temporal (diel time course) and spatial (across a leaf gradient) gene and microRNA (miRNA) expression patterns in the obligate CAM plant pineapple [Ananas comosus (L.) Merr.]. The high-resolution transcriptome atlas allowed us to distinguish between CAM-related and non-CAM gene copies. A differential gene co-expression network across green and white leaf diel datasets identified genes with circadian oscillation, CAM-related functions, and source-sink relations. Gene co-expression clusters containing CAM pathway genes are enriched with clock-associated cis-elements, suggesting circadian regulation of CAM. About 20% of pineapple microRNAs have diel expression patterns, with several that target key CAM-related genes. Expression and physiology data provide a model for CAM-specific carbohydrate flux and long-distance hexose transport. Together these resources provide a list of candidate genes for targeted engineering of CAM into C 3 photosynthesis crop species. © 2017 The Authors The Plant Journal © 2017 John Wiley & Sons Ltd.

  10. Spatio-Temporal Dynamic Analysis of Sustainable Development in China Based on the Footprint Family.

    Science.gov (United States)

    Zhao, Jing; Ma, Caihong; Zhao, Xiangui; Wang, Xiaoyu

    2018-02-01

    The existing index systems on sustainable evaluation are mostly based on a multi index comprehensive evaluation method. The main disadvantage of this approach is that the selection and assignment of evaluation indexes are greatly influenced by subjective factors, which can result in poor comparability of results. By contrast, the Footprint Family (including ecological footprint, carbon footprint, and water footprint) is not affected by subjective factors. The Footprint Family also covers the basic tenets of sustainable development. This paper proposes use of a sustainable development evaluation index system based on the principle of the Footprint Family, and including the ecological pressure index ( EPI ), the ecological occupancy index ( EOI ), the ecological economic coordination index ( EECI ), the GHG (Greenhouse Gas) emission index ( CEI ), the water resources stress index ( WSI ), and the sustainable development index ( SDI ). Furthermore, a standard for grading the evaluated results based on global benchmarks is formulated. The results of an empirical study in China were the following. The development situation deteriorated from 1990 to 2015. The results showed that the SDI decreased from a medium level (grade 5) to a lower-medium level (grade 4). The results of this empirical study also showed that the method of evaluation can avoid the influence of subjective factors and can be used in the evaluation of sustainable development for various temporal and spatial conditions.

  11. Temporal dynamics of fish communities on an exposed shoreline in Hawaii

    Science.gov (United States)

    Friedlander, A.M.; Parrish, J.D.

    1998-01-01

    Environmental conditions on higher latitude coral reefs can be extremely variable, and may structure fish communities in ways not previously observed in the more stable, low latitude locations where communities have usually been studied. Temporal changes in fish community structure were examined in an intensive two-year study of the reef fishes of Hanalei Bay, Kauai, Hawaii. Hanalei Bay is directly exposed to winter swells with high surf, as well as frequent heavy winter rainfall and high river discharge. Twenty-two transects (25 x 5 m) were established in a wide variety of habitats and censused monthly (N = 1052 censuses). Over 121 000 sightings of individuals from 150 species were made during the study. Seasonal patterns in number of species, number of individuals, species diversity, and evenness were observed, with winter values usually lowest. Values of these ensemble variables tended to be higher at deeper sites and at sites with greater habitat complexity. Surf height and degree of wave exposure were negatively correlated with several measures of community organization. Groups of fishes with different levels of spatial mobility tended to occupy depths consistent with their various abilities to respond to events of heavy weather. The rank abundance of fish taxa tended to be more stable seasonally at sites with less exposure to high wave energy. These seasonal effects may suggest some type of short-range movement from more exposed and monotypic habitats to locations that are deeper or otherwise provide refuge from seasonally heavy seas.

  12. Dynamic changes during evacuation of a left temporal abscess in open MRI: technical case report

    International Nuclear Information System (INIS)

    Bernays, R.L.; Yonekawa, Y.; Kollias, S.S.

    2002-01-01

    We demonstrate the usefulness of ''near real-time'' neuro-navigation by open MRI systems for guidance of stereotactic evacuation of intracranial abscesses. A 70-year-old patient was referred to our institution with an intracranial left temporal abscess. He presented with headache, senso-motor aphasia and mild right hemiparesis. The abscess (35 x 25 mm) was stereotactically evacuated under MRI guidance, and a recurrence of a daughter abscess was again evacuated on the 9th postoperative day. ''Near real-time'' imaging showed an indentation of the abscess wall of 11 mm along the trajectory. A thermosensitive MRI protocol demonstrated a higher temperature around the abscess capsule than in the brain tissue more distant to the capsule, demonstrating the inflammatory process. The patient had 6 weeks of antibiotic therapy for gram-negative bacteria and was discharged with improved clinical symptoms 5 weeks after admission. Follow-up CT 2 months postoperatively showed a complete resolution of the abscess. Open MRI-guided interventions with ''near real-time'' imaging demonstrate the anatomical changes during an ongoing procedure and can be accommodated for enhancing the overall precision of stereotactic procedures. Thermosensitive MRI protocols are capable of revealing temperature gradients around inflammatory processes. (orig.)

  13. A Model of the Spatio-temporal Dynamics of Drosophila Eye Disc Development.

    Directory of Open Access Journals (Sweden)

    Patrick Fried

    2016-09-01

    Full Text Available Patterning and growth are linked during early development and have to be tightly controlled to result in a functional tissue or organ. During the development of the Drosophila eye, this linkage is particularly clear: the growth of the eye primordium mainly results from proliferating cells ahead of the morphogenetic furrow (MF, a moving signaling wave that sweeps across the tissue from the posterior to the anterior side, that induces proliferating cells anterior to it to differentiate and become cell cycle quiescent in its wake. Therefore, final eye disc size depends on the proliferation rate of undifferentiated cells and on the speed with which the MF sweeps across the eye disc. We developed a spatio-temporal model of the growing eye disc based on the regulatory interactions controlled by the signals Decapentaplegic (Dpp, Hedgehog (Hh and the transcription factor Homothorax (Hth and explored how the signaling patterns affect the movement of the MF and impact on eye disc growth. We used published and new quantitative data to parameterize the model. In particular, two crucial parameter values, the degradation rate of Hth and the diffusion coefficient of Hh, were measured. The model is able to reproduce the linear movement of the MF and the termination of growth of the primordium. We further show that the model can explain several mutant phenotypes, but fails to reproduce the previously observed scaling of the Dpp gradient in the anterior compartment.

  14. Optical and Temporal Carrier Dynamics Investigations of III-Nitrides for Semiconductor Lighting

    KAUST Repository

    Ajia, Idris A.

    2018-01-01

    In the first part of this dissertation, the effects of some important types of crystal defects present in III-nitride structures are investigated. Here, two types of defects are studied in two different III-nitride-based light emitting structures. The first defects of interest are V-pit defects in InGaN/GaN multiple quantum well (MQW) blue LEDs, where their contribution to the high-efficiency of such LEDs is discussed. In addition, the effect of these defects on the efficiency droop phenomenon in these LEDs is elucidated. Secondly, the optical effects of grain boundary defects in AlN-rich AlGaN/AlGaN MQWs is studied. In this study, it is shown that grain boundary defects may result in abnormal carrier localization behavior in these deep ultraviolet (UV) structures. While both defects are treated individually, it is evident from these studies that threading dislocation (TD) defects are an underlying contributor to the more undesirable outcomes of the said defects. In the second part, the dissertation reports on the carrier dynamics of III-nitride LED structures grown on emerging substrates—as possible efficiency enhancing techniques—aimed at mitigating the effects of TD defects. Thus, the carrier dynamics of GaN/AlGaN UV MQWs grown, for the first time, on (2̅01) – oriented β-Ga2O3 is studied. It is shown to be a candidate substrate for highly efficient vertical UV devices. Finally, results from the carrier dynamics investigation of an AlGaN/AlGaN MQW LED structure homoepitaxially grown on AlN substrate are discussed, where it is shown that its high-efficiency is sustained at high temperatures through the thermal redistribution of carriers to highly efficient recombination sites.

  15. Electroencephalogram Similarity Analysis Using Temporal and Spectral Dynamics Analysis for Propofol and Desflurane Induced Unconsciousness

    Directory of Open Access Journals (Sweden)

    Quan Liu

    2018-01-01

    Full Text Available Important information about the state dynamics of the brain during anesthesia is unraveled by Electroencephalogram (EEG approaches. Patterns that are observed through EEG related to neural circuit mechanism under different molecular targets dependent anesthetics have recently attracted much attention. Propofol, a Gamma-amino butyric acid, is known with evidently increasing alpha oscillation. Desflurane shares the same receptor action and should be similar to propofol. To explore their dynamics, EEG under routine surgery level anesthetic depth is analyzed using multitaper spectral method from two groups: propofol (n = 28 and desflurane (n = 23. The time-varying spectrum comparison was undertaken to characterize their properties. Results show that both of the agents are dominated by slow and alpha waves. Especially, for increased alpha band feature, propofol unconsciousness shows maximum power at about 10 Hz (mean ± SD; frequency: 10.2 ± 1.4 Hz; peak power, −14.0 ± 1.6 dB, while it is approximate about 8 Hz (mean ± SD; frequency: 8.3 ± 1.3 Hz; peak power, −13.8 ± 1.6 dB for desflurane with significantly lower frequency-resolved spectra for this band. In addition, the mean power of propofol is much higher from alpha to gamma band, including slow oscillation than that of desflurane. The patterns might give us an EEG biomarker for specific anesthetic. This study suggests that both of the anesthetics exhibit similar spectral dynamics, which could provide insight into some common neural circuit mechanism. However, differences between them also indicate their uniqueness where relevant.

  16. The shape and temporal dynamics of phylogenetic trees arising from geographic speciation.

    Science.gov (United States)

    Pigot, Alex L; Phillimore, Albert B; Owens, Ian P F; Orme, C David L

    2010-12-01

    Phylogenetic trees often depart from the expectations of stochastic models, exhibiting imbalance in diversification among lineages and slowdowns in the rate of lineage accumulation through time. Such departures have led to a widespread perception that ecological differences among species or adaptation and subsequent niche filling are required to explain patterns of diversification. However, a key element missing from models of diversification is the geographical context of speciation and extinction. In this study, we develop a spatially explicit model of geographic range evolution and cladogenesis, where speciation arises via vicariance or peripatry, and explore the effects of these processes on patterns of diversification. We compare the results with those observed in 41 reconstructed avian trees. Our model shows that nonconstant rates of speciation and extinction are emergent properties of the apportioning of geographic ranges that accompanies speciation. The dynamics of diversification exhibit wide variation, depending on the mode of speciation, tendency for range expansion, and rate of range evolution. By varying these parameters, the model is able to capture many, but not all, of the features exhibited by birth-death trees and extant bird clades. Under scenarios with relatively stable geographic ranges, strong slowdowns in diversification rates are produced, with faster rates of range dynamics leading to constant or accelerating rates of apparent diversification. A peripatric model of speciation with stable ranges also generates highly unbalanced trees typical of bird phylogenies but fails to produce realistic range size distributions among the extant species. Results most similar to those of a birth-death process are reached under a peripatric speciation scenario with highly volatile range dynamics. Taken together, our results demonstrate that considering the geographical context of speciation and extinction provides a more conservative null model of

  17. Optical and Temporal Carrier Dynamics Investigations of III-Nitrides for Semiconductor Lighting

    KAUST Repository

    Ajia, Idris A.

    2018-05-22

    III-nitride semiconductors suffer significant efficiency limitations; ‘efficiency’ being an umbrella term that covers an extensive list of challenges that must be overcome if they are to fulfil their vast potential. To this end, it is imperative to understand the underlying phenomena behind such limitations. In this dissertation, I combine powerful optical and structural characterization techniques to investigate the effect of different defects on the carrier dynamics in III-nitride materials for light emitting devices. The results presented herein will enhance the current understanding of the carrier mechanisms in such devices, which will lead to device efficiency improvements. In the first part of this dissertation, the effects of some important types of crystal defects present in III-nitride structures are investigated. Here, two types of defects are studied in two different III-nitride-based light emitting structures. The first defects of interest are V-pit defects in InGaN/GaN multiple quantum well (MQW) blue LEDs, where their contribution to the high-efficiency of such LEDs is discussed. In addition, the effect of these defects on the efficiency droop phenomenon in these LEDs is elucidated. Secondly, the optical effects of grain boundary defects in AlN-rich AlGaN/AlGaN MQWs is studied. In this study, it is shown that grain boundary defects may result in abnormal carrier localization behavior in these deep ultraviolet (UV) structures. While both defects are treated individually, it is evident from these studies that threading dislocation (TD) defects are an underlying contributor to the more undesirable outcomes of the said defects. In the second part, the dissertation reports on the carrier dynamics of III-nitride LED structures grown on emerging substrates—as possible efficiency enhancing techniques—aimed at mitigating the effects of TD defects. Thus, the carrier dynamics of GaN/AlGaN UV MQWs grown, for the first time, on (2̅01) – oriented β-Ga2O

  18. Temporal changes in vegetation of a virgin beech woodland remnant: stand-scale stability with intensive fine-scale dynamics governed by stand dynamic events

    Directory of Open Access Journals (Sweden)

    Tibor Standovár

    2017-03-01

    Full Text Available The aim of this resurvey study is to check if herbaceous vegetation on the forest floor exhibits overall stability at the stand-scale in spite of intensive dynamics at the scale of individual plots and stand dynamic events (driven by natural fine scale canopy gap dynamics. In 1996, we sampled a 1.5 ha patch using 0.25 m² plots placed along a 5 m × 5 m grid in the best remnant of central European montane beech woods in Hungary. All species in the herbaceous layer and their cover estimates were recorded. Five patches representing different stand developmental situations (SDS were selected for resurvey. In 2013, 306 plots were resurveyed by using blocks of four 0.25 m² plots to test the effects of imperfect relocation. We found very intensive fine-scale dynamics in the herbaceous layer with high species turnover and sharp changes in ground layer cover at the local-scale (< 1 m2. A decrease in species richness and herbaceous layer cover, as well as high species turnover, characterized the closing gaps. Colonization events and increasing species richness and herbaceous layer cover prevailed in the two newly created gaps. A pronounced decrease in the total cover, but low species turnover and survival of the majority of the closed forest specialists was detected by the resurvey at the stand-scale. The test aiming at assessing the effect of relocation showed a higher time effect than the effect of imprecise relocation. The very intensive fine-scale dynamics of the studied beech forest are profoundly determined by natural stand dynamics. Extinction and colonisation episodes even out at the stand-scale, implying an overall compositional stability of the herbaceous vegetation at the given spatial and temporal scale. We argue that fine-scale gap dynamics, driven by natural processes or applied as a management method, can warrant the survival of many closed forest specialist species in the long-run. Nomenclature: Flora Europaea (Tutin et al. 2010 for

  19. Temporal functional analysis of dynamic scintigraphy by application of the Karhunen-Loeve transform

    International Nuclear Information System (INIS)

    Girardot-Verdenet, Josette.

    1981-01-01

    Four main themes are dealt with in four different chapters. The first describes the scintigraphic data acquisition system: gamma camera and computer, as well as the various types of examination performed. Chapter two develops the subject of image processing techniques, especially as applied to kidney and heart scintigraphs which cover all problems encountered by doctors in the interpretation of a dynamic scintigraph. Chapter three is devoted to the formalism of Karhunen-Loeve transformation, the method best suited for data sorting because alone able to achieve a compression of this data in the sense of the mean quadratic error. The method is applied in chapter four to obtain functional heart and kidney images. The demarcation of the outlines of organs is often imprecise and two neighbouring zones developing at different rates have been differentiated by application of the Fukunaga-Koontz transformation which uses the properties of the Kahrunen-Loeve transformation in the case of heart scintigraphy where ventricles and auricles are superimposed. The aim of this work is to find out whether the compression of data for the Kahrunen-Loeve transformation provides any objective elements in the interpretation of dynamic scintigraphs [fr

  20. Spatio-temporal dynamics of maize yield water constraints under climate change in Spain.

    Science.gov (United States)

    Ferrero, Rosana; Lima, Mauricio; Gonzalez-Andujar, Jose Luis

    2014-01-01

    Many studies have analyzed the impact of climate change on crop productivity, but comparing the performance of water management systems has rarely been explored. Because water supply and crop demand in agro-systems may be affected by global climate change in shaping the spatial patterns of agricultural production, we should evaluate how and where irrigation practices are effective in mitigating climate change effects. Here we have constructed simple, general models, based on biological mechanisms and a theoretical framework, which could be useful in explaining and predicting crop productivity dynamics. We have studied maize in irrigated and rain-fed systems at a provincial scale, from 1996 to 2009 in Spain, one of the most prominent "hot-spots" in future climate change projections. Our new approach allowed us to: (1) evaluate new structural properties such as the stability of crop yield dynamics, (2) detect nonlinear responses to climate change (thresholds and discontinuities), challenging the usual linear way of thinking, and (3) examine spatial patterns of yield losses due to water constraints and identify clusters of provinces that have been negatively affected by warming. We have reduced the uncertainty associated with climate change impacts on maize productivity by improving the understanding of the relative contributions of individual factors and providing a better spatial comprehension of the key processes. We have identified water stress and water management systems as being key causes of the yield gap, and detected vulnerable regions where efforts in research and policy should be prioritized in order to increase maize productivity.

  1. Temporal dynamics of motivation-cognitive control interactions revealed by high-resolution pupillometry

    Directory of Open Access Journals (Sweden)

    Kimberly Sarah Chiew

    2013-01-01

    Full Text Available Motivational manipulations, such as the presence of performance-contingent reward incentives, can have substantial influences on cognitive control. Previous evidence suggests that reward incentives may enhance cognitive performance specifically through increased preparatory, or proactive, control processes. The present study examined reward influences on cognitive control dynamics in the AX-Continuous Performance Task (AX-CPT, using high-resolution pupillometry. In the AX-CPT, contextual cues must be actively maintained over a delay in order to appropriately respond to ambiguous target probes. A key feature of the task is that it permits dissociable characterization of preparatory, proactive control processes (i.e., utilization of context and reactive control processes (i.e., target-evoked interference resolution. Task performance profiles suggested that reward incentives enhanced proactive control (context utilization. Critically, pupil dilation was also increased on reward incentive trials during context maintenance periods, suggesting trial-specific shifts in proactive control, particularly when context cues indicated the need to overcome the dominant target response bias. Reward incentives had both transient (i.e., trial-by-trial and sustained (i.e., block-based effects on pupil dilation, which may reflect distinct underlying processes. The transient pupillary effects were present even when comparing against trials matched in task performance, suggesting a unique motivational influence of reward incentives. These results suggest that pupillometry may be a useful technique for investigating reward motivational signals and their dynamic influence on cognitive control.

  2. Spatial and temporal dynamics of drosophilid larval assemblages associated to fruits

    Directory of Open Access Journals (Sweden)

    Renata Alves da Mata

    2015-03-01

    Full Text Available The study of organisms and their resources is critical to further understanding population dynamics in space and time. Although drosophilids have been widely used as biological models, their relationship with breeding and feeding sites has received little attention. Here, we investigate drosophilids breeding in fruits in the Brazilian Savanna, in two contrasting vegetation types, throughout 16 months. Specifically, larval assemblages were compared between savannas and forests, as well as between rainy and dry seasons. The relationships between resource availability and drosophilid abundance and richness were also tested. The community (4,022 drosophilids of 23 species and 2,496 fruits of 57 plant taxa varied widely in space and time. Drosophilid assemblages experienced a strong bottleneck during the dry season, decreasing to only 0.5% of the abundance of the rainy season. Additionally, savannas displayed lower richness and higher abundance than the forests, and were dominated by exotic species. Both differences in larval assemblages throughout the year and between savannas and gallery forests are consistent with those previously seen in adults. Although the causes of this dynamic are clearly multifactorial, resource availability (richness and abundance of rotten fruits was a good predictor of the fly assemblage structure.

  3. Swim-training changes the spatio-temporal dynamics of skeletogenesis in zebrafish larvae (Danio rerio.

    Directory of Open Access Journals (Sweden)

    Ansa W Fiaz

    Full Text Available Fish larvae experience many environmental challenges during development such as variation in water velocity, food availability and predation. The rapid development of structures involved in feeding, respiration and swimming increases the chance of survival. It has been hypothesized that mechanical loading induced by muscle forces plays a role in prioritizing the development of these structures. Mechanical loading by muscle forces has been shown to affect larval and embryonic bone development in vertebrates, but these investigations were limited to the appendicular skeleton. To explore the role of mechanical load during chondrogenesis and osteogenesis of the cranial, axial and appendicular skeleton, we subjected zebrafish larvae to swim-training, which increases physical exercise levels and presumably also mechanical loads, from 5 until 14 days post fertilization. Here we show that an increased swimming activity accelerated growth, chondrogenesis and osteogenesis during larval development in zebrafish. Interestingly, swim-training accelerated both perichondral and intramembranous ossification. Furthermore, swim-training prioritized the formation of cartilage and bone structures in the head and tail region as well as the formation of elements in the anal and dorsal fins. This suggests that an increased swimming activity prioritized the development of structures which play an important role in swimming and thereby increasing the chance of survival in an environment where water velocity increases. Our study is the first to show that already during early zebrafish larval development, skeletal tissue in the cranial, axial and appendicular skeleton is competent to respond to swim-training due to increased water velocities. It demonstrates that changes in water flow conditions can result into significant spatio-temporal changes in skeletogenesis.

  4. Spatial and Temporal Dynamics of Aphids (Hemiptera: Aphididae) in the Columbia Basin and Northeastern Oregon.

    Science.gov (United States)

    Klein, Mathew L; Rondon, Silvia I; Walenta, Darrin L; Zeb, Qamar; Murphy, Alexzandra F

    2017-08-01

    Aphid species, such as the potato aphid, Macrosiphum euphorbiae Thomas, and the green peach aphid, Myzus persicae Sulzer, are routinely considered the most important pests of potatoes. Potato aphid, green peach aphid, and more recently, other aphids such as the bird cherry-oat aphid Rhopalosiphum padi L. have been identified as vectors of multiple plant pathogenic viruses in potatoes. Since 2006, an area-wide trapping network consisting of ∼60 sites was developed through collaboration between researchers, extension faculty, and stakeholders, to monitor aphid populations in the Columbia Basin of Oregon (Umatilla and Morrow counties) and in northeastern Oregon (Union and Baker counties). Over a 9-yr period (2006 to 2014), aphid specimens were collected weekly using yellow bucket traps and specimens were then identified and counted to determine population levels during the growing season (May-September). Thus, aphid population data were compiled and subjected to spatial and temporal distribution analysis. Weather data, obtained from an established network of weather stations located in the monitoring areas, were used in a nonparametric multiplicative regression analysis to determine which abiotic variables may impact aphid populations. Weather conditions were characterized using confidence intervals (CIs) established based on weather data from 1999 to 2005 for each environmental variable. Aphid populations were found to have a heterogeneous distribution in most years; a few sites had high aphid populations while low numbers were observed at most sites; aphids were also found to correlate with several abiotic variables, namely, elevation, previous season temperature, and previous season dew point. © The Authors 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  5. Spatio-temporal dynamics of global H5N1 outbreaks match bird migration patterns

    Directory of Open Access Journals (Sweden)

    Yali Si

    2009-11-01

    Full Text Available The global spread of highly pathogenic avian influenza H5N1 in poultry, wild birds and humans, poses a significant pandemic threat and a serious public health risk. An efficient surveillance and disease control system relies on the understanding of the dispersion patterns and spreading mechanisms of the virus. A space-time cluster analysis of H5N1 outbreaks was used to identify spatio-temporal patterns at a global scale and over an extended period of time. Potential mechanisms explaining the spread of the H5N1 virus, and the role of wild birds, were analyzed. Between December 2003 and December 2006, three global epidemic phases of H5N1 influenza were identified. These H5N1 outbreaks showed a clear seasonal pattern, with a high density of outbreaks in winter and early spring (i.e., October to March. In phase I and II only the East Asia Australian flyway was affected. During phase III, the H5N1 viruses started to appear in four other flyways: the Central Asian flyway, the Black Sea Mediterranean flyway, the East Atlantic flyway and the East Africa West Asian flyway. Six disease cluster patterns along these flyways were found to be associated with the seasonal migration of wild birds. The spread of the H5N1 virus, as demonstrated by the space-time clusters, was associated with the patterns of migration of wild birds. Wild birds may therefore play an important role in the spread of H5N1 over long distances. Disease clusters were also detected at sites where wild birds are known to overwinter and at times when migratory birds were present. This leads to the suggestion that wild birds may also be involved in spreading the H5N1 virus over short distances.

  6. Temporal dynamics of retinal and extraretinal signals in the FEFsem during smooth pursuit eye movements.

    Science.gov (United States)

    Bakst, Leah; Fleuriet, Jérome; Mustari, Michael J

    2017-05-01

    Neurons in the smooth eye movement subregion of the frontal eye field (FEFsem) are known to play an important role in voluntary smooth pursuit eye movements. Underlying this function are projections to parietal and prefrontal visual association areas and subcortical structures, all known to play vital but differing roles in the execution of smooth pursuit. Additionally, the FEFsem has been shown to carry a diverse array of signals (e.g., eye velocity, acceleration, gain control). We hypothesized that distinct subpopulations of FEFsem neurons subserve these diverse functions and projections, and that the relative weights of retinal and extraretinal signals could form the basis for categorization of units. To investigate this, we used a step-ramp tracking task with a target blink to determine the relative contributions of retinal and extraretinal signals in individual FEFsem neurons throughout pursuit. We found that the contributions of retinal and extraretinal signals to neuronal activity and behavior change throughout the time course of pursuit. A clustering algorithm revealed three distinct neuronal subpopulations: cluster 1 was defined by a higher sensitivity to eye velocity, acceleration, and retinal image motion; cluster 2 had greater activity during blinks; and cluster 3 had significantly greater eye position sensitivity. We also performed a comparison with a sample of medial superior temporal neurons to assess similarities and differences between the two areas. Our results indicate the utility of simple tests such as the target blink for parsing the complex and multifaceted roles of cortical areas in behavior. NEW & NOTEWORTHY The frontal eye field (FEF) is known to play a critical role in volitional smooth pursuit, carrying a variety of signals that are distributed throughout the brain. This study used a novel application of a target blink task during step ramp tracking to determine, in combination with a clustering algorithm, the relative contributions of

  7. Temporal Dynamics of Sodic Playa Salt Crust Patterns: Implications for Aeolian Dust Emission Potential

    Science.gov (United States)

    Nield, J. M.; King, J.; Bryant, R. G.; Wiggs, G.; Eckardt, F. D.; Thomas, D. S.; Washington, R.

    2013-12-01

    Salt pans (or playas) are common in arid environments and can be major sources of windblown mineral dust, but there are uncertainties associated with their dust emission potential. These landforms typically form crusts which modify both their erosivity and erodibility by limiting sediment availability, modifying surface and aerodynamic roughness and limiting evaporation rates and sediment production. Here we show the relationship between seasonal surface moisture change and crust pattern development based on both remote-sensing and field surface and atmospheric measurements. We use high resolution (sub-cm) terrestrial laser scanning (TLS; ground-based lidar) surveys over weekly, monthly and annual timescales to accurately characterise crustal ridge thrusting and collapse. This can be as much as 2 mm/day on fresh pan areas that have recently been reset by flooding. Over a two month period, this ridge growth can change aerodynamic roughness length values by 6.5 mm. At the same time, crack densities across the surface increase and this raises the availability of erodible fluffy, low density dust source sediment stored below the crust layer. Ridge spaces are defined in the early stages of crust development, as identified by Fourier Transform analysis, but wider wavelengths become more pronounced over time. We present a conceptual model accounting for the driving forces (subsurface, surface and atmospheric moisture) and feedbacks between these and surface shape that lead to crust pattern trajectories between highly emissive degraded surfaces and less emissive ridged or continuous crusts. These findings improve our understanding of temporal changes in dust availability and supply from playa source regions.

  8. Temporal dynamics of ocular position dependence of the initial human vestibulo-ocular reflex.

    Science.gov (United States)

    Crane, Benjamin T; Tian, Junru; Demer, Joseph L

    2006-04-01

    While an ideal vestibulo-ocular reflex (VOR) generates ocular rotations compensatory for head motion, during visually guided movements, Listing's Law (LL) constrains the eye to rotational axes lying in Listing's Plane (LP). The present study was conducted to explore the recent proposal that the VOR's rotational axis is not collinear with the head's, but rather follows a time-dependent strategy intermediate between LL and an ideal VOR. Binocular LPs were defined during visual fixation in eight normal humans. The VOR was evoked by a highly repeatable transient whole-body yaw rotation in darkness at a peak acceleration of 2800 deg/s2. Immediately before rotation, subjects regarded targets 15 or 500 cm distant located at eye level, 20 degrees up, or 20 degrees down. Eye and head responses were compared with LL predictions in the position and velocity domains. LP orientation varied both among subjects and between individual subject's eyes, and rotated temporally with convergence by 5 +/- 5 degrees (+/-SEM). In the position domain, the eye compensated for head displacement even when the head rotated out of LP. Even within the first 20 ms from onset of head rotation, the ocular velocity axis tilted relative to the head axis by 30% +/- 8% of vertical gaze position. Saccades increased this tilt. Regardless of vertical gaze position, the ocular rotation axis tilted backward 4 degrees farther in abduction than in adduction. There was also a binocular vertical eye velocity transient and lateral tilt of the ocular axis. These disconjugate, short-latency axis perturbations appear intrinsic to the VOR and may have neural or mechanical origins.

  9. Nonmonotonic and spatial-temporal dynamic slope effects on soil erosion during rainfall-runoff processes

    Science.gov (United States)

    Wu, Songbai; Yu, Minghui; Chen, Li

    2017-02-01

    The slope effect on flow erosivity and soil erosion still remains a controversial issue. This theoretical framework explained and quantified the direct slope effect by coupling the modified Green-Ampt equation accounting for slope effect on infiltration, 1-D kinematic wave overland flow routing model, and WEPP soil erosion model. The flow velocity, runoff rate, shear stress, interrill, and rill erosion were calculated on 0°-60° isotropic slopes with equal horizontal projective length. The results show that, for short-duration rainfall events, the flow erosivity and erosion amounts exhibit a bell-shaped trend which first increase with slope gradient, and then decrease after a critical slope angle. The critical slope angles increase significantly or even vanish with increasing rainfall duration but are nearly independent of the slope projective length. The soil critical shear stress, rainfall intensity, and temporal patterns have great influences on the slope effect trend, while the other soil erosion parameters, soil type, hydraulic conductivity, and antecedent soil moisture have minor impacts. Neglecting the slope effect on infiltration would generate smaller erosion and reduce critical slope angles. The relative slope effect on soil erosion in physically based model WEPP was compared to those in the empirical models USLE and RUSLE. The trends of relative slope effect were found quite different, but the difference may diminish with increasing rainfall duration. Finally, relatively smaller critical slope angles could be obtained with the equal slope length and the range of variation provides a possible explanation for the different critical slope angles reported in previous studies.

  10. Spatial and temporal dynamics of deep percolation, lag time and recharge in an irrigated semi-arid region

    Science.gov (United States)

    Nazarieh, F.; Ansari, H.; Ziaei, A. N.; Izady, A.; Davari, K.; Brunner, P.

    2018-05-01

    The time required for deep percolating water to reach the water table can be considerable in areas with a thick vadose zone. Sustainable groundwater management, therefore, has to consider the spatial and temporal dynamics of groundwater recharge. The key parameters that control the lag time have been widely examined in soil physics using small-scale lysimeters and modeling studies. However, only a small number of studies have analyzed how deep-percolation rates affect groundwater recharge dynamics over large spatial scales. This study examined how the parameters influencing lag time affect groundwater recharge in a semi-arid catchment under irrigation (in northeastern Iran) using a numerical modeling approach. Flow simulations were performed by the MODFLOW-NWT code with the Vadose-Zone Flow (UZF) Package. Calibration of the groundwater model was based on data from 48 observation wells. Flow simulations showed that lag times vary from 1 to more than 100 months. A sensitivity analysis demonstrated that during drought conditions, the lag time was highly sensitive to the rate of deep percolation. The study illustrated two critical points: (1) the importance of providing estimates of the lag time as a basis for sustainable groundwater management, and (2) lag time not only depends on factors such as soil hydraulic conductivity or vadose zone depth but also depends on the deep-percolation rates and the antecedent soil-moisture condition. Therefore, estimates of the lag time have to be associated with specific percolation rates, in addition to depth to groundwater and soil properties.

  11. High fidelity visualization of cell-to-cell variation and temporal dynamics in nascent extracellular matrix formation.

    Science.gov (United States)

    McLeod, Claire M; Mauck, Robert L

    2016-12-12

    Extracellular matrix dynamics are key to tissue morphogenesis, homeostasis, injury, and repair. The spatiotemporal organization of this matrix has profound biological implications, but is challenging to monitor using standard techniques. Here, we address these challenges by using noncanonical amino acid tagging to fluorescently label extracellular matrix synthesized in the presence of bio-orthogonal methionine analogs. This strategy labels matrix proteins with high resolution, without compromising their distribution or mechanical function. We demonstrate that the organization and temporal dynamics of the proteinaceous matrix depend on the biophysical features of the microenvironment, including the biomaterial scaffold and the niche constructed by cells themselves. Pulse labeling experiments reveal that, in immature constructs, nascent matrix is highly fibrous and interdigitates with pre-existing matrix, while in more developed constructs, nascent matrix lacks fibrous organization and is retained in the immediate pericellular space. Inhibition of collagen crosslinking increases matrix synthesis, but compromises matrix organization. Finally, these data demonstrate marked cell-to-cell heterogeneity amongst both chondrocytes and mesenchymal stem cells undergoing chondrogenesis. Collectively, these results introduce fluorescent noncanonical amino acid tagging as a strategy to investigate spatiotemporal matrix organization, and demonstrate its ability to identify differences in phenotype, microenvironment, and matrix assembly at the single cell level.

  12. Automated on-line liquid–liquid extraction system for temporal mass spectrometric analysis of dynamic samples

    Energy Technology Data Exchange (ETDEWEB)

    Hsieh, Kai-Ta; Liu, Pei-Han [Department of Applied Chemistry, National Chiao Tung University, 1001 University Rd, Hsinchu, 300, Taiwan (China); Urban, Pawel L. [Department of Applied Chemistry, National Chiao Tung University, 1001 University Rd, Hsinchu, 300, Taiwan (China); Institute of Molecular Science, National Chiao Tung University, 1001 University Rd, Hsinchu, 300, Taiwan (China)

    2015-09-24

    Most real samples cannot directly be infused to mass spectrometers because they could contaminate delicate parts of ion source and guides, or cause ion suppression. Conventional sample preparation procedures limit temporal resolution of analysis. We have developed an automated liquid–liquid extraction system that enables unsupervised repetitive treatment of dynamic samples and instantaneous analysis by mass spectrometry (MS). It incorporates inexpensive open-source microcontroller boards (Arduino and Netduino) to guide the extraction and analysis process. Duration of every extraction cycle is 17 min. The system enables monitoring of dynamic processes over many hours. The extracts are automatically transferred to the ion source incorporating a Venturi pump. Operation of the device has been characterized (repeatability, RSD = 15%, n = 20; concentration range for ibuprofen, 0.053–2.000 mM; LOD for ibuprofen, ∼0.005 mM; including extraction and detection). To exemplify its usefulness in real-world applications, we implemented this device in chemical profiling of pharmaceutical formulation dissolution process. Temporal dissolution profiles of commercial ibuprofen and acetaminophen tablets were recorded during 10 h. The extraction-MS datasets were fitted with exponential functions to characterize the rates of release of the main and auxiliary ingredients (e.g. ibuprofen, k = 0.43 ± 0.01 h{sup −1}). The electronic control unit of this system interacts with the operator via touch screen, internet, voice, and short text messages sent to the mobile phone, which is helpful when launching long-term (e.g. overnight) measurements. Due to these interactive features, the platform brings the concept of the Internet-of-Things (IoT) to the chemistry laboratory environment. - Highlights: • Mass spectrometric analysis normally requires sample preparation. • Liquid–liquid extraction can isolate analytes from complex matrices. • The proposed system automates

  13. Automated on-line liquid–liquid extraction system for temporal mass spectrometric analysis of dynamic samples

    International Nuclear Information System (INIS)

    Hsieh, Kai-Ta; Liu, Pei-Han; Urban, Pawel L.

    2015-01-01

    Most real samples cannot directly be infused to mass spectrometers because they could contaminate delicate parts of ion source and guides, or cause ion suppression. Conventional sample preparation procedures limit temporal resolution of analysis. We have developed an automated liquid–liquid extraction system that enables unsupervised repetitive treatment of dynamic samples and instantaneous analysis by mass spectrometry (MS). It incorporates inexpensive open-source microcontroller boards (Arduino and Netduino) to guide the extraction and analysis process. Duration of every extraction cycle is 17 min. The system enables monitoring of dynamic processes over many hours. The extracts are automatically transferred to the ion source incorporating a Venturi pump. Operation of the device has been characterized (repeatability, RSD = 15%, n = 20; concentration range for ibuprofen, 0.053–2.000 mM; LOD for ibuprofen, ∼0.005 mM; including extraction and detection). To exemplify its usefulness in real-world applications, we implemented this device in chemical profiling of pharmaceutical formulation dissolution process. Temporal dissolution profiles of commercial ibuprofen and acetaminophen tablets were recorded during 10 h. The extraction-MS datasets were fitted with exponential functions to characterize the rates of release of the main and auxiliary ingredients (e.g. ibuprofen, k = 0.43 ± 0.01 h"−"1). The electronic control unit of this system interacts with the operator via touch screen, internet, voice, and short text messages sent to the mobile phone, which is helpful when launching long-term (e.g. overnight) measurements. Due to these interactive features, the platform brings the concept of the Internet-of-Things (IoT) to the chemistry laboratory environment. - Highlights: • Mass spectrometric analysis normally requires sample preparation. • Liquid–liquid extraction can isolate analytes from complex matrices. • The proposed system automates the

  14. Spatio-temporal dynamics of word selection in speech production: Insights from electrocorticography

    Directory of Open Access Journals (Sweden)

    Stephanie K Ries

    2015-04-01

    Our results suggest that the posterior inferior LTC is involved in word selection as semantic concepts become available. Posterior medial and left PFC regions may be involved in trial-by-trial top-down control over LTC to help overcome interference caused by semantically-related alternatives in word selection. The single-case result supports this hypothesis and suggests that the posterior medial PFC plays a causal role in resolving this interference in word selection. Lastly, the sensitivity to semantic interference of the post-vocal onset posterior LTC activity suggests the semantic interference effect does not only reflect word selection difficulty but is also present at post-selection stages such as verbal response monitoring. In sum, this study reveals a dynamic network of interacting brain regions that support word selection in language production.

  15. Working-memory load and temporal myopia in dynamic decision making.

    Science.gov (United States)

    Worthy, Darrell A; Otto, A Ross; Maddox, W Todd

    2012-11-01

    We examined the role of working memory (WM) in dynamic decision making by having participants perform decision-making tasks under single-task or dual-task conditions. In 2 experiments participants performed dynamic decision-making tasks in which they chose 1 of 2 options on each trial. The decreasing option always gave a larger immediate reward but caused future rewards for both options to decrease. The increasing option always gave a smaller immediate reward but caused future rewards for both options to increase. In each experiment we manipulated the reward structure such that the decreasing option was the optimal choice in 1 condition and the increasing option was the optimal choice in the other condition. Behavioral results indicated that dual-task participants selected the immediately rewarding decreasing option more often, and single-task participants selected the increasing option more often, regardless of which option was optimal. Thus, dual-task participants performed worse on 1 type of task but better on the other type. Modeling results showed that single-task participants' data were most often best fit by a win-stay, lose-shift (WSLS) rule-based model that tracked differences across trials, and dual-task participants' data were most often best fit by a Softmax reinforcement learning model that tracked recency-weighted average rewards for each option. This suggests that manipulating WM load affects the degree to which participants focus on the immediate versus delayed consequences of their actions and whether they employ a rule-based WSLS strategy, but it does not necessarily affect how well people weigh the immediate versus delayed benefits when determining the long-term utility of each option.

  16. Spatio-temporal dynamics of maize yield water constraints under climate change in Spain.

    Directory of Open Access Journals (Sweden)

    Rosana Ferrero

    Full Text Available Many studies have analyzed the impact of climate change on crop productivity, but comparing the performance of water management systems has rarely been explored. Because water supply and crop demand in agro-systems may be affected by global climate change in shaping the spatial patterns of agricultural production, we should evaluate how and where irrigation practices are effective in mitigating climate change effects. Here we have constructed simple, general models, based on biological mechanisms and a theoretical framework, which could be useful in explaining and predicting crop productivity dynamics. We have studied maize in irrigated and rain-fed systems at a provincial scale, from 1996 to 2009 in Spain, one of the most prominent "hot-spots" in future climate change projections. Our new approach allowed us to: (1 evaluate new structural properties such as the stability of crop yield dynamics, (2 detect nonlinear responses to climate change (thresholds and discontinuities, challenging the usual linear way of thinking, and (3 examine spatial patterns of yield losses due to water constraints and identify clusters of provinces that have been negatively affected by warming. We have reduced the uncertainty associated with climate change impacts on maize productivity by improving the understanding of the relative contributions of individual factors and providing a better spatial comprehension of the key processes. We have identified water stress and water management systems as being key causes of the yield gap, and detected vulnerable regions where efforts in research and policy should be prioritized in order to increase maize productivity.

  17. Temporal Dynamics of the Driving Factors of Urban Landscape Change of Addis Ababa During the Past Three Decades.

    Science.gov (United States)

    Zewdie, Meskerem; Worku, Hailu; Bantider, Amare

    2018-01-01

    Mapping and quantifying urban landscape dynamics and the underlying driving factors are crucial for devising appropriate policies, especially in cities of developing countries where the change is rapid. This study analyzed three decades (1984-2014) of land use land cover change of Addis Ababa using Landsat imagery and examined the underlying factors and their temporal dynamics through expert interview using Analytic Hierarchy Process (AHP). Classification results revealed that urban area increased by 50%, while agricultural land and forest decreased by 34 and 16%, respectively. The driving factors operated differently during the pre and post-1991 period. The year 1991 was chosen because it marked government change in the country resulting in policy change. Policy had the highest influence during the pre-1991 period. Land use change in this period was associated with the housing sector as policies and institutional setups were permissive to this sector. Population growth and in-migration were also important factors. Economic factors played significant role in the post-1991 period. The fact that urban land has a market value, the growth of private investment, and the speculated property market were among the economic factors. Policy reforms since 2003 were also influential to the change. Others such as accessibility, demography, and neighborhood factors were a response to economic factors. All the above-mentioned factors had vital role in shaping the urban pattern of the city. These findings can help planners and policymakers to better understand the dynamic relationship of urban land use and the driving factors to better manage the city.

  18. Internal cycling, not external loading, decides the nutrient limitation in eutrophic lake: A dynamic model with temporal Bayesian hierarchical inference.

    Science.gov (United States)

    Wu, Zhen; Liu, Yong; Liang, Zhongyao; Wu, Sifeng; Guo, Huaicheng

    2017-06-01

    Lake eutrophication is associated with excessive anthropogenic nutrients (mainly nitrogen (N) and phosphorus (P)) and unobserved internal nutrient cycling. Despite the advances in understanding the role of external loadings, the contribution of internal nutrient cycling is still an open question. A dynamic mass-balance model was developed to simulate and measure the contributions of internal cycling and external loading. It was based on the temporal Bayesian Hierarchical Framework (BHM), where we explored the seasonal patterns in the dynamics of nutrient cycling processes and the limitation of N and P on phytoplankton growth in hyper-eutrophic Lake Dianchi, China. The dynamic patterns of the five state variables (Chla, TP, ammonia, nitrate and organic N) were simulated based on the model. Five parameters (algae growth rate, sediment exchange rate of N and P, nitrification rate and denitrification rate) were estimated based on BHM. The model provided a good fit to observations. Our model results highlighted the role of internal cycling of N and P in Lake Dianchi. The internal cycling processes contributed more than external loading to the N and P changes in the water column. Further insights into the nutrient limitation analysis indicated that the sediment exchange of P determined the P limitation. Allowing for the contribution of denitrification to N removal, N was the more limiting nutrient in most of the time, however, P was the more important nutrient for eutrophication management. For Lake Dianchi, it would not be possible to recover solely by reducing the external watershed nutrient load; the mechanisms of internal cycling should also be considered as an approach to inhibit the release of sediments and to enhance denitrification. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. Temporal Dynamics of the Driving Factors of Urban Landscape Change of Addis Ababa During the Past Three Decades

    Science.gov (United States)

    Zewdie, Meskerem; Worku, Hailu; Bantider, Amare

    2018-01-01

    Mapping and quantifying urban landscape dynamics and the underlying driving factors are crucial for devising appropriate policies, especially in cities of developing countries where the change is rapid. This study analyzed three decades (1984-2014) of land use land cover change of Addis Ababa using Landsat imagery and examined the underlying factors and their temporal dynamics through expert interview using Analytic Hierarchy Process (AHP). Classification results revealed that urban area increased by 50%, while agricultural land and forest decreased by 34 and 16%, respectively. The driving factors operated differently during the pre and post-1991 period. The year 1991 was chosen because it marked government change in the country resulting in policy change. Policy had the highest influence during the pre-1991 period. Land use change in this period was associated with the housing sector as policies and institutional setups were permissive to this sector. Population growth and in-migration were also important factors. Economic factors played significant role in the post-1991 period. The fact that urban land has a market value, the growth of private investment, and the speculated property market were among the economic factors. Policy reforms since 2003 were also influential to the change. Others such as accessibility, demography, and neighborhood factors were a response to economic factors. All the above-mentioned factors had vital role in shaping the urban pattern of the city. These findings can help planners and policymakers to better understand the dynamic relationship of urban land use and the driving factors to better manage the city.

  20. Temporal dynamics of European bat Lyssavirus type 1 and survival of Myotis myotis bats in natural colonies.

    Science.gov (United States)

    Amengual, Blanca; Bourhy, Hervé; López-Roig, Marc; Serra-Cobo, Jordi

    2007-06-27

    Many emerging RNA viruses of public health concern have recently been detected in bats. However, the dynamics of these viruses in natural bat colonies is presently unknown. Consequently, prediction of the spread of these viruses and the establishment of appropriate control measures are hindered by a lack of information. To this aim, we collected epidemiological, virological and ecological data during a twelve-year longitudinal study in two colonies of insectivorous bats (Myotis myotis) located in Spain and infected by the most common bat lyssavirus found in Europe, the European bat lyssavirus subtype 1 (EBLV-1). This active survey demonstrates that cyclic lyssavirus infections occurred with periodic oscillations in the number of susceptible, immune and infected bats. Persistence of immunity for more than one year was detected in some individuals. These data were further used to feed models to analyze the temporal dynamics of EBLV-1 and the survival rate of bats. According to these models, the infection is characterized by a predicted low basic reproductive rate (R(0) = 1.706) and a short infectious period (D = 5.1 days). In contrast to observations in most non-flying animals infected with rabies, the survival model shows no variation in mortality after EBLV-1 infection of M. myotis. These findings have considerable public health implications in terms of management of colonies where lyssavirus-positive bats have been recorded and confirm the potential risk of rabies transmission to humans. A greater understanding of the dynamics of lyssavirus in bat colonies also provides a model to study how bats contribute to the maintenance and transmission of other viruses of public health concern.

  1. Temporal dynamics of European bat Lyssavirus type 1 and survival of Myotis myotis bats in natural colonies.

    Directory of Open Access Journals (Sweden)

    Blanca Amengual

    Full Text Available Many emerging RNA viruses of public health concern have recently been detected in bats. However, the dynamics of these viruses in natural bat colonies is presently unknown. Consequently, prediction of the spread of these viruses and the establishment of appropriate control measures are hindered by a lack of information. To this aim, we collected epidemiological, virological and ecological data during a twelve-year longitudinal study in two colonies of insectivorous bats (Myotis myotis located in Spain and infected by the most common bat lyssavirus found in Europe, the European bat lyssavirus subtype 1 (EBLV-1. This active survey demonstrates that cyclic lyssavirus infections occurred with periodic oscillations in the number of susceptible, immune and infected bats. Persistence of immunity for more than one year was detected in some individuals. These data were further used to feed models to analyze the temporal dynamics of EBLV-1 and the survival rate of bats. According to these models, the infection is characterized by a predicted low basic reproductive rate (R(0 = 1.706 and a short infectious period (D = 5.1 days. In contrast to observations in most non-flying animals infected with rabies, the survival model shows no variation in mortality after EBLV-1 infection of M. myotis. These findings have considerable public health implications in terms of management of colonies where lyssavirus-positive bats have been recorded and confirm the potential risk of rabies transmission to humans. A greater understanding of the dynamics of lyssavirus in bat colonies also provides a model to study how bats contribute to the maintenance and transmission of other viruses of public health concern.

  2. An investigation into the effects of temporal resolution on hepatic dynamic contrast-enhanced MRI in volunteers and in patients with hepatocellular carcinoma

    International Nuclear Information System (INIS)

    Gill, Andrew B; Graves, Martin J; Lomas, David J; Black, Richard T; Bowden, David J; Priest, Andrew N

    2014-01-01

    This study investigated the effect of temporal resolution on the dual-input pharmacokinetic (PK) modelling of dynamic contrast-enhanced MRI (DCE-MRI) data from normal volunteer livers and from patients with hepatocellular carcinoma. Eleven volunteers and five patients were examined at 3 T. Two sections, one optimized for the vascular input functions (VIF) and one for the tissue, were imaged within a single heart-beat (HB) using a saturation-recovery fast gradient echo sequence. The data was analysed using a dual-input single-compartment PK model. The VIFs and/or uptake curves were then temporally sub-sampled (at interval ▵t = [2–20] s) before being subject to the same PK analysis. Statistical comparisons of tumour and normal tissue PK parameter values using a 5% significance level gave rise to the same study results when temporally sub-sampling the VIFs to HB < ▵t <4 s. However, sub-sampling to ▵t > 4 s did adversely affect the statistical comparisons. Temporal sub-sampling of just the liver/tumour tissue uptake curves at ▵t ≤ 20 s, whilst using high temporal resolution VIFs, did not substantially affect PK parameter statistical comparisons. In conclusion, there is no practical advantage to be gained from acquiring very high temporal resolution hepatic DCE-MRI data. Instead the high temporal resolution could be usefully traded for increased spatial resolution or SNR. (paper)

  3. Market Orientation within University Schools of Business: Can a Dynamical Systems Viewpoint Applied to a Non-Temporal Data Set Yield Valuable Insights for University Managers?

    Science.gov (United States)

    Cox, John C.; Webster, Robert L.; Hammond, Kevin L.

    2009-01-01

    This study investigates the use of using complexity theory--the study of nonlinear dynamical systems of which chaos and catastrophe theory are subsets--in the analysis of a non temporal data set to derive valuable insights into the functioning of university schools of business. The approach is unusual in that studies of nonlinearity in complex…

  4. Influenza A virus evolution and spatio-temporal dynamics in eurasian wild birds: A phylogenetic and phylogeographical study of whole-genome sequence data

    NARCIS (Netherlands)

    N.S. Lewis (Nicola); J.H. Verhagen (Josanne); Z. Javakhishvili (Zurab); C.A. Russell (Colin); P. Lexmond (Pascal); K.B. Westgeest (Kim); T.M. Bestebroer (Theo); R.A. Halpin (Rebecca); X. Lin (Xudong); A. Ransier (Amy); N.B. Fedorova (Nadia B.); T.B. Stockwell (Timothy B.); N. Latorre-Margalef (Neus); B. Olsen (Björn); G.J.D. Smith (Gavin); J. Bahl (Justin); D.E. Wentworth (David E.); J. Waldenström (Jonas); R.A.M. Fouchier (Ron); M.T. de Graaf (Marieke)

    2015-01-01

    textabstractLow pathogenic avian influenza A viruses (IAVs) have a natural host reservoir in wild waterbirds and the potential to spread to other host species. Here, we investigated the evolutionary, spatial and temporal dynamics of avian IAVs in Eurasian wild birds. We used whole-genome sequences

  5. Improvement of temporal and dynamic subtraction images on abdominal CT using 3D global image matching and nonlinear image warping techniques

    International Nuclear Information System (INIS)

    Okumura, E; Sanada, S; Suzuki, M; Takemura, A; Matsui, O

    2007-01-01

    Accurate registration of the corresponding non-enhanced and arterial-phase CT images is necessary to create temporal and dynamic subtraction images for the enhancement of subtle abnormalities. However, respiratory movement causes misregistration at the periphery of the liver. To reduce these misregistration errors, we developed a temporal and dynamic subtraction technique to enhance small HCC by 3D global matching and nonlinear image warping techniques. The study population consisted of 21 patients with HCC. Using the 3D global matching and nonlinear image warping technique, we registered current and previous arterial-phase CT images or current non-enhanced and arterial-phase CT images obtained in the same position. The temporal subtraction image was obtained by subtracting the previous arterial-phase CT image from the warped current arterial-phase CT image. The dynamic subtraction image was obtained by the subtraction of the current non-enhanced CT image from the warped current arterial-phase CT image. The percentage of fair or superior temporal subtraction images increased from 52.4% to 95.2% using the new technique, while on the dynamic subtraction images, the percentage increased from 66.6% to 95.2%. The new subtraction technique may facilitate the diagnosis of subtle HCC based on the superior ability of these subtraction images to show nodular and/or ring enhancement

  6. Spatial and Temporal Dynamics of Potentially Toxic Cyanobacteria in the Riverine Region of a Temperate Estuarine System Altered by Weirs

    Directory of Open Access Journals (Sweden)

    Jacqueline Martha Malazarte

    2017-10-01

    Full Text Available The effects of weirs on fish and other biological communities have garnered considerable study, whereas the effects of weirs on community composition of toxic cyanobacteria have not yet been well documented. In this study, temporal and spatial variations in species composition and the abundance of potentially toxic cyanobacteria were investigated in the riverine regions of the temperate Youngsan River estuary, where two weirs have recently been constructed. Four stations were sampled 0.5 m below the surface monthly along the channel of the upper river from May 2014 to April 2015 to explore cyanobacterial composition and abundance, while physicochemical and biological parameters were measured to elucidate possible mechanisms controlling these dynamics. Two stations were located upstream at free-flowing sites, and the other stations were located downstream at impounded sites near the weirs. Twenty-eight cyanobacterial species were identified, seven of which were potentially toxic: Microcystis sp., M. aeruginosa, M. flos-aquae, Dolichospermum sp., Aphanocapsa sp., Oscillatoria sp. and Phormidium sp. Microcystis sp. was the most abundant in June 2014 at the lowest station near the weir. Meanwhile, Phormidium sp. occurred at low abundance throughout the study period, except during the winter months, when its abundance was elevated. The interactive forward selection method highlighted dissolved inorganic nitrogen and zooplankton abundance as explanatory variables for this observed variation, but their effects on cyanobacterial growth are unclear. However, temperature was the major determinant for the temporal variation in cyanobacterial populations. Cluster analysis showed that the downstream stations near the weirs had a high similarity of potentially toxic cyanobacteria. Significantly higher abundance, especially of Microcystis sp., was also recorded at the impounded sites suggesting that the presence of weirs might affect variations in toxic

  7. Temporal Dynamics of Arthropods on Six Tree Species in Dry Woodlands on the Caribbean Island of Puerto Rico

    Science.gov (United States)

    Beltrán, William; Wunderle, Joseph M.

    2014-01-01

    Abstract The seasonal dynamics of foliage arthropod populations are poorly studied in tropical dry forests despite the importance of these studies for understanding arthropod population responses to environmental change. We monitored the abundance, temporal distributions, and body size of arthropods in five naturalized alien and one native tree species to characterize arthropod seasonality in dry novel Prosopis–Leucaena woodlands in Puerto Rico. A branch clipping method was used monthly to sample foliage arthropod abundance over 39 mo. Seasonal patterns of rainfall and abundance within various arthropod taxa were highly variable from year to year. Abundance for most taxa did not show significant seasonality over the 3 yr, although most taxa had abundance peaks each year. However, Homoptera displayed high seasonality with significant temporal aggregations in each year. Formicidae, Orthoptera, and Coleoptera showed high variation in abundance between wet and dry periods, whereas Hemiptera were consistently more abundant in the wet period. Seasonal differences in mean abundance were found only in a few taxa on Tamarindus indica L. , Bucida buceras L. , Pithecellobium dulce , and (Roxburgh) Benth. Mean arthropod abundance varied among tree species, with highest numbers on Prosopis juliflora , (Swartz) De Candolle, Pi. dulce , Leucaena leucocephala , and (Lamarck) de Wit. Abundance of Araneae, Orthoptera, Coleoptera, Lepidoptera larvae, and all arthropods showed weak relationships with one or more climatic variables (rainfall, maximum temperature, or relative humidity). Body size of arthropods was usually largest during the dry periods. Overall, total foliage arthropod abundance showed no consistent seasonality among years, which may become a more common trend in dry forests and woodlands in the Caribbean if seasonality of rainfall becomes less predictable. PMID:25502036

  8. The temporal dynamics of implicit processing of non-letter, letter, and word-forms in the human visual cortex

    Directory of Open Access Journals (Sweden)

    Lawrence Gregory Appelbaum

    2009-11-01

    Full Text Available The decoding of visually presented line segments into letters, and letters into words, is critical to fluent reading abilities. Here we investigate the temporal dynamics of visual orthographic processes, focusing specifically on right hemisphere contributions and interactions between the hemispheres involved in the implicit processing of visually presented words, consonants, false fonts, and symbolic strings. High-density EEG was recorded while participants detected infrequent, simple, perceptual targets (dot strings embedded amongst a of character strings. Beginning at 130ms, orthographic and non-orthographic stimuli were distinguished by a sequence of ERP effects over occipital recording sites. These early latency occipital effects were dominated by enhanced right-sided negative-polarity activation for non-orthographic stimuli that peaked at around 180ms. This right-sided effect was followed by bilateral positive occipital activity for false-fonts, but not symbol strings. Moreover the size of components of this later positive occipital wave was inversely correlated with the right-sided ROcc180 wave, suggesting that subjects who had larger early right-sided activation for non-orthographic stimuli had less need for more extended bilateral (e.g. interhemispheric processing of those stimuli shortly later. Additional early (130-150ms negative-polarity activity over left occipital cortex and longer-latency centrally distributed responses (>300ms were present, likely reflecting implicit activation of the previously reported ‘visual-word-form’ area and N400-related responses, respectively. Collectively, these results provide a close look at some relatively unexplored portions of the temporal flow of information processing in the brain related to the implicit processing of potentially linguistic information and provide valuable information about the interactions between hemispheres supporting visual orthographic processing.

  9. Temporal dynamics of arthropods on six tree species in dry woodlands on the Caribbean Island of Puerto Rico.

    Science.gov (United States)

    Beltrán, William; Wunderle, Joseph M

    2014-01-01

    The seasonal dynamics of foliage arthropod populations are poorly studied in tropical dry forests despite the importance of these studies for understanding arthropod population responses to environmental change. We monitored the abundance, temporal distributions, and body size of arthropods in five naturalized alien and one native tree species to characterize arthropod seasonality in dry novel Prosopis-Leucaena woodlands in Puerto Rico. A branch clipping method was used monthly to sample foliage arthropod abundance over 39 mo. Seasonal patterns of rainfall and abundance within various arthropod taxa were highly variable from year to year. Abundance for most taxa did not show significant seasonality over the 3 yr, although most taxa had abundance peaks each year. However, Homoptera displayed high seasonality with significant temporal aggregations in each year. Formicidae, Orthoptera, and Coleoptera showed high variation in abundance between wet and dry periods, whereas Hemiptera were consistently more abundant in the wet period. Seasonal differences in mean abundance were found only in a few taxa on Tamarindus indica L., Bucida buceras L., Pithecellobium dulce, and (Roxburgh) Benth. Mean arthropod abundance varied among tree species, with highest numbers on Prosopis juliflora, (Swartz) De Candolle, Pi. dulce, Leucaena leucocephala, and (Lamarck) de Wit. Abundance of Araneae, Orthoptera, Coleoptera, Lepidoptera larvae, and all arthropods showed weak relationships with one or more climatic variables (rainfall, maximum temperature, or relative humidity). Body size of arthropods was usually largest during the dry periods. Overall, total foliage arthropod abundance showed no consistent seasonality among years, which may become a more common trend in dry forests and woodlands in the Caribbean if seasonality of rainfall becomes less predictable. © The Author 2014. Published by Oxford University Press on behalf of the Entomological Society of America.

  10. Process Inference from High Frequency Temporal Variations in Dissolved Organic Carbon (DOC) Dynamics Across Nested Spatial Scales

    Science.gov (United States)

    Tunaley, C.; Tetzlaff, D.; Lessels, J. S.; Soulsby, C.

    2014-12-01

    In order to understand aquatic ecosystem functioning it is critical to understand the processes that control the spatial and temporal variations in DOC. DOC concentrations are highly dynamic, however, our understanding at short, high frequency timescales is still limited. Optical sensors which act as a proxy for DOC provide the opportunity to investigate near-continuous DOC variations in order to understand the hydrological and biogeochemical processes that control concentrations at short temporal scales. Here we present inferred 15 minute stream water DOC data for a 12 month period at three nested scales (1km2, 3km2 and 31km2) for the Bruntland Burn, a headwater catchment in NE Scotland. High frequency data were measured using FDOM and CDOM probes which work by measuring the fluorescent component and coloured component, respectively, of DOC when exposed to ultraviolet light. Both FDOM and CDOM were strongly correlated (r2 >0.8) with DOC allowing high frequency estimations. Results show the close coupling of DOC with discharge throughout the sampling period at all three spatial scales. However, analysis at the event scale highlights anticlockwise hysteresis relationships between DOC and discharge due to the delay in DOC being flushed from the increasingly large areas of peaty soils as saturation zones expand and increase hydrological connectivity. Lag times vary between events dependent on antecedent conditions. During a 10 year drought period in late summer 2013 it was apparent that very small changes in discharge on a 15 minute timescale result in high increases in DOC. This suggests transport limitation during this period where DOC builds up in the soil and is not flushed regularly, therefore any subsequent increase in discharge results in large DOC peaks. The high frequency sensors also reveal diurnal variability during summer months related to the photo-oxidation, evaporative and biological influences of DOC during the day. This relationship is less

  11. Temporal variation in the specific dynamic action of juvenile New Zealand rock lobsters, Jasus edwardsii.

    Science.gov (United States)

    Radford, Craig A; Marsden, Islay D; Davison, William

    2004-09-01

    To enhance the on-growing of Jasus edwardsii in culture, it is important to understand the feeding physiology of juveniles. In crustaceans, there is a loss of energy and an increase in oxygen consumption (specific dynamic action or SDA) associated with feeding. The present research measured the SDA of juvenile J. edwardsii fed either in the morning or at night held at 15 degrees C. Closed box respirometry was used to measure oxygen consumption (MO(2)) and ammonia excretion in juvenile lobsters. Juveniles exhibited a nocturnal rhythm in both MO(2) and ammonia excretion. The factorial rise in MO(2) (1.58+/-0.03 times) for lobsters fed in the morning was significantly less than lobsters fed at night (1.80+/-0.01 times). Lobsters fed in the morning had a significantly shorter SDA (30+/-1.2 h) response compared to lobsters fed at night (36+/-1 h). Energy loss as a result of digestion was less for lobsters fed in the morning. Therefore, if juvenile J. edwardsii are fed in the morning, they could optimise the energy content of the meal and this could result in increased growth.

  12. Neural substrates and behavioral profiles of romantic jealousy and its temporal dynamics.

    Science.gov (United States)

    Sun, Yan; Yu, Hongbo; Chen, Jie; Liang, Jie; Lu, Lin; Zhou, Xiaolin; Shi, Jie

    2016-06-07

    Jealousy is not only a way of experiencing love but also a stabilizer of romantic relationships, although morbid romantic jealousy is maladaptive. Being engaged in a formal romantic relationship can tune one's romantic jealousy towards a specific target. Little is known about how the human brain processes romantic jealousy by now. Here, by combining scenario-based imagination and functional MRI, we investigated the behavioral and neural correlates of romantic jealousy and their development across stages (before vs. after being in a formal relationship). Romantic jealousy scenarios elicited activations primarily in the basal ganglia (BG) across stages, and were significantly higher after the relationship was established in both the behavioral rating and BG activation. The intensity of romantic jealousy was related to the intensity of romantic happiness, which mainly correlated with ventral medial prefrontal cortex activation. The increase in jealousy across stages was associated with the tendency for interpersonal aggression. These results bridge the gap between the theoretical conceptualization of romantic jealousy and its neural correlates and shed light on the dynamic changes in jealousy.

  13. Dynamic adjustments in prefrontal, hippocampal, and inferior temporal interactions with increasing visual working memory load.

    Science.gov (United States)

    Rissman, Jesse; Gazzaley, Adam; D'Esposito, Mark

    2008-07-01

    The maintenance of visual stimuli across a delay interval in working memory tasks is thought to involve reverberant neural communication between the prefrontal cortex and posterior visual association areas. Recent studies suggest that the hippocampus might also contribute to this retention process, presumably via reciprocal interactions with visual regions. To characterize the nature of these interactions, we performed functional connectivity analysis on an event-related functional magnetic resonance imaging data set in which participants performed a delayed face recognition task. As the number of faces that participants were required to remember was parametrically increased, the right inferior frontal gyrus (IFG) showed a linearly decreasing degree of functional connectivity with the fusiform face area (FFA) during the delay period. In contrast, the hippocampus linearly increased its delay period connectivity with both the FFA and the IFG as the mnemonic load increased. Moreover, the degree to which participants' FFA showed a load-dependent increase in its connectivity with the hippocampus predicted the degree to which its connectivity with the IFG decreased with load. Thus, these neural circuits may dynamically trade off to accommodate the particular mnemonic demands of the task, with IFG-FFA interactions mediating maintenance at lower loads and hippocampal interactions supporting retention at higher loads.

  14. Assessment of temporal dynamics of evaporation in the Itumbiara reservoir, GO, using remote sensing data

    Directory of Open Access Journals (Sweden)

    João Antônio Lorenzzetti

    2013-04-01

    Full Text Available The object of this work was to study the dynamics of evaporation in the Itumbiara reservoir, located in Central Brazil, using MODIS-derived water surface temperature (product MOD11A1 and meteorological data acquired over the water surface. The evaporation rates were derived from latent heat flux, estimated through a mass transfer model. The estimates were carried out for the period between 1/1/2010 and 31/12/2010. The results showed that evaporation rate tends to increase from January to September and then decrease from September to December. The evaporation rate reached values near 20 mm day-1 in Itumbiara reservoir during the dry season in 2010. The mean evaporation rate for the wet season was 3.66 mm day-1 and 8.25 mm day-1 for the dry season. The total water volume evaporated from Itumbiara reservoir during 2010 was estimated at about 1.7 billion m³ (2,300 mm which represents 10% of total reservoir volume. The results suggest that advection is the main transport mechanism which drives the evaporation in Itumbiara. The convective processes contribute secondarily to evaporation in Itumbiara reservoir.

  15. [Spatial and temporal dynamics of the weed community in the Zoysia matrella lawn].

    Science.gov (United States)

    Liu, Jia-Qi; Li, You-Han; Zeng, Ying; Xie, Xin-Ming

    2014-02-01

    The heterogeneity of species composition is one of the main attributes in weed community dynamics. Based on species frequency and power law, this paper studied the variations of weed community species composition and spatial heterogeneity in a Zoysia matrella lawn in Guangzhou at different time. The results showed that there were 43 weed species belonging to 19 families in the Z. matrella lawn from 2007 to 2009, in which Gramineae, Compositae, Cyperaceae and Rubiaceae had a comparative advantage. Perennial weeds accounted for the largest proportion of weeds and increased gradually in the three years. Weed communities distributed in higher heterogeneity than in a random model. Dominant weeds varied with season and displayed regularity in the order of 'dicotyledon-monocotyledon-dicotyledon weeds' and 'perennial-annual-perennial weeds'. The spatial heterogeneity of weed community in Z. matrella lawn was higher in summer than in winter. The diversity and evenness of weed community were higher in summer and autumn than in winter and spring. The number of weed species with high heterogeneity in summer was higher than in the other seasons. The spatial heterogeneity and diversity of weed community had no significant change in the three years, while the evenness of weed community had the tendency to decline gradually.

  16. DISCOVERY 2010: Spatial and temporal variability in a dynamic polar ecosystem

    Science.gov (United States)

    Tarling, G. A.; Ward, P.; Atkinson, A.; Collins, M. A.; Murphy, E. J.

    2012-01-01

    DIC deficits, the South Georgia bloom was found to contain the strongest seasonal carbon uptake in the ice-free zone of the Southern Ocean. The surveys also encountered low-production, iron-limited regions, a situation more typical of the wider Southern Ocean. The response of primary and secondary consumers to spatial and temporal heterogeneity in production was complex. Many of the life-cycles of small pelagic organisms showed a close coupling to the seasonal cycle of food availability. For instance, Antarctic krill showed a dependence on early, non-ice-associated blooms to facilitate early reproduction. Strategies to buffer against environmental variability were also examined, such as the prevalence of multiyear life-cycles and variability in energy storage levels. Such traits were seen to influence the way in which Scotia Sea communities were structured, with biomass levels in the larger size classes being higher than in other ocean regions. Seasonal development also altered trophic function, with the trophic level of higher predators increasing through the course of the year as additional predator-prey interactions emerged in the lower trophic levels. Finally, our studies re-emphasised the role that the simple phytoplankton-krill-higher predator food chain plays in this Southern Ocean region, particularly south of the SACCF. To the north, alternative food chains, such as those involving copepods, macrozooplankton and mesopelagic fish, were increasingly important. Continued ocean warming in this region is likely to increase the prevalence of such alternative such food chains with Antarctic krill predicted to move southwards.

  17. Spatio-temporal dynamics of surface water quality in a Portuguese peri-urban catchment

    Science.gov (United States)

    Ferreira, Carla; Walsh, Rory; Coelho, Celeste; Ferreira, António

    2016-04-01

    Urban development poses great pressure on water resources, but the impact of different land-uses on streamwater quality in partly urbanized catchments is not well understood. Focussing on a Portuguese peri-urban catchment, this paper explores the impact of a mosaic of different urban and non-urban land-uses on streamwater quality, and the influence of a seasonal Mediterranean climate on pollutant dynamics. The catchment has a 40% urban cover, dispersed amongst patches of woodland (56%) and agricultural fields (4%). Apart from the catchment outlet, streamwater quality was assessed at three sub-catchment sites: (i) Porto Bordalo, encompassing a 39% urban area with a new major road; (ii) Espírito Santo, draining a sub-catchment with 49% urban cover, mostly comprising detached houses surrounded by gardens; and (iii) Quinta, with a 25% urban cover. The Porto Bordalo sub-catchment is underlain by limestone, whereas the Espírito Santo and Quinta sub-catchments overlie sandstone. Water quality variables (notably nutrients, heavy metals and COD) were assessed for samples collected at different stages in the storm hydrograph responses to ten rainfall events occurring between October 2011 and March 2013. Urban areas had great impacts on COD, with highest median concentrations in Espírito Santo (18.0 mg L-1) and lowest in Quinta (9.5 mgL-1). In Espírito Santo, the management of gardens triggered greatest median concentrations of N-NO3 (1.46 mgL-1, purban patterns and storm drainage system, should help enable urban planners to minimize adverse impacts of urbanization on water quality.

  18. Anxiety and depression among adolescents with attention-deficit/hyperactivity disorder: The roles of behavioral temperamental traits, comorbid autism spectrum disorder, and bullying involvement

    Directory of Open Access Journals (Sweden)

    Huei-Fan Hu

    2016-02-01

    Full Text Available The aim of this study was to examine the associations of behavioral temperamental traits, comorbid autism spectrum disorder (ASD, and bullying involvement with anxiety and depression among adolescents with attention-deficit/hyperactivity disorder (ADHD in Taiwan. A total of 287 adolescents aged 11–18 years diagnosed with ADHD participated in this study. Their severities of anxiety and depression were assessed. Multiple regression analysis was used to examine the correlates of anxiety and depression. The results show that adolescents with ADHD who reported a higher behavioral inhibition system (BIS score, had comorbid ASD, and were bullying victims, reported more severe anxiety and depressive symptoms. Adolescents with ADHD who bullied others reported more severe depressive symptoms than those who did not bully. The results of this study indicated that behavioral temperamental traits on the BIS, comorbid ASD, and bullying involvement were significantly associated with anxiety and depression among the adolescents with ADHD.

  19. Electrophysiological evidence for temporal dynamics associated with attentional processing in the zoom lens paradigm

    Directory of Open Access Journals (Sweden)

    Qing Zhang

    2018-04-01

    expansion of the attentional focus, suggesting that observers might further redistribute attentional resources according to the increased task difficulty. Conclusion These findings provide electrophysiological evidence that the neural activity of the N1 generator is the earliest marker of the zoom lens effect of visual spatial attention. Furthermore, evidence from N2pc shows that there is also a redistribution of attentional resources after the action of the zoom lens mechanism, which allows for better perform of the search task in the context of low attentional resolution. On the basis of the timing of P1, N1, and N2pc, our findings provide compelling evidence that visuospatial attention processing in the zoom lens paradigm involves multi-stage dynamic processing.

  20. Temporal dynamic of malaria in a suburban area along the Niger River.

    Science.gov (United States)

    Sissoko, Mahamadou Soumana; Sissoko, Kourane; Kamate, Bourama; Samake, Yacouba; Goita, Siaka; Dabo, Abdoulaye; Yena, Mama; Dessay, Nadine; Piarroux, Renaud; Doumbo, Ogobara K; Gaudart, Jean

    2017-10-23

    Even if rainfall and temperature are factors classically associated to malaria, little is known about other meteorological factors, their variability and combinations related to malaria, in association with river height variations. Furthermore, in suburban area, urbanization and growing population density should be assessed in relation to these environmental factors. The aim of this study was to assess the impact of combined environmental, meteorological and hydrological factors on malaria incidence through time in the context of urbanization. Population observational data were prospectively collected. Clinical malaria was defined as the presence of parasites in addition to clinical symptoms. Meteorological and hydrological factors were measured daily. For each factors variation indices were estimated. Urbanization was yearly estimated assessing satellite imaging and field investigations. Principal component analysis was used for dimension reduction and factors combination. Lags between malaria incidences and the main components were assessed by cross-correlation functions. Generalized additive model was used to assess relative impact of different environmental components, taking into account lags, and modelling non-linear relationships. Change-point analysis was used to determine transmission periods within years. Malaria incidences were dominated by annual periodicity and varied through time without modification of the dynamic, with no impact of the urbanization. The main meteorological factor associated with malaria was a combination of evaporation, humidity and rainfall, with a lag of 3 months. The relationship between combined temperature factors showed a linear impact until reaching high temperatures limiting malaria incidence, with a lag 3.25 months. Height and variation of the river were related to malaria incidence (respectively 6 week lag and no lag). The study emphasizes no decreasing trend of malaria incidence despite accurate access to care and

  1. Temporal dynamics of iris yellow spot virus and its vector, Thrips tabaci (Thysanoptera: Thripidae), in seeded and transplanted onion fields.

    Science.gov (United States)

    Hsu, Cynthia L; Hoepting, Christine A; Fuchs, Marc; Shelton, Anthony M; Nault, Brian A

    2010-04-01

    Onion thrips, Thrips tabaci (Lindeman) (Thysanoptera: Thripidae), can reduce onion bulb yield and transmit iris yellow spot virus (IYSV) (Bunyaviridae: Tospovirus), which can cause additional yield losses. In New York, onions are planted using seeds and imported transplants. IYSV is not seed transmitted, but infected transplants have been found in other U.S. states. Transplants are also larger than seeded onions early in the season, and thrips, some of which may be viruliferous, may preferentially colonize larger plants. Limited information is available on the temporal dynamics of IYSV and its vector in onion fields. In 2007 and 2008, T. tabaci and IYSV levels were monitored in six seeded and six transplanted fields. We found significantly more thrips in transplanted fields early in the season, but by the end of the season seeded fields had higher levels of IYSV. The percentage of sample sites with IYSV-infected plants remained low (fields. The densities of adult and larval thrips in August and September were better predictors of final IYSV levels than early season thrips densities. For 2007 and 2008, the time onions were harvested may have been more important in determining IYSV levels than whether the onions were seeded or transplanted. Viruliferous thrips emigrating from harvested onion fields into nonharvested ones may be increasing the primary spread of IYSV in late-harvested onions. Managing T. tabaci populations before harvest, and manipulating the spatial arrangement of fields based on harvest date could mitigate the spread of IYSV.

  2. Dynamics of Viral Abundance and Diversity in a Sphagnum-Dominated Peatland: Temporal Fluctuations Prevail Over Habitat.

    Science.gov (United States)

    Ballaud, Flore; Dufresne, Alexis; Francez, André-Jean; Colombet, Jonathan; Sime-Ngando, Télesphore; Quaiser, Achim

    2015-01-01

    Viruses impact microbial activity and carbon cycling in various environments, but their diversity and ecological importance in Sphagnum-peatlands are unknown. Abundances of viral particles and prokaryotes were monitored bi-monthly at a fen and a bog at two different layers of the peat surface. Viral particle abundance ranged from 1.7 x 10(6) to 5.6 x 10(8) particles mL(-1), and did not differ between fen and bog but showed seasonal fluctuations. These fluctuations were positively correlated with prokaryote abundance and dissolved organic carbon, and negatively correlated with water-table height and dissolved oxygen. Using shotgun metagenomics we observed a shift in viral diversity between winter/spring and summer/autumn, indicating a seasonal succession of viral communities, mainly driven by weather-related environmental changes. Based on the seasonal asynchrony between viral and microbial diversity, we hypothesize a seasonal shift in the active microbial communities associated with a shift from lysogenic to lytic lifestyles. Our results suggest that temporal variations of environmental conditions rather than current habitat differences control the dynamics of virus-host interactions in Sphagnum-dominated peatlands.

  3. Neural evidence for moral intuition and the temporal dynamics of interactions between emotional processes and moral cognition.

    Science.gov (United States)

    Gui, Dan-Yang; Gan, Tian; Liu, Chao

    2016-01-01

    Behavioral and neurological studies have revealed that emotions influence moral cognition. Although moral stimuli are emotionally charged, the time course of interactions between emotions and moral judgments remains unknown. In the present study, we investigated the temporal dynamics of the interaction between emotional processes and moral cognition. The results revealed that when making moral judgments, the time course of the event-related potential (ERP) waveform was significantly different between high emotional arousal and low emotional arousal contexts. Different stages of processing were distinguished, showing distinctive interactions between emotional processes and moral reasoning. The precise time course of moral intuition and moral reasoning sheds new light on theoretical models of moral psychology. Specifically, the N1 component (interpreted as representing moral intuition) did not appear to be influenced by emotional arousal. However, the N2 component and late positive potential were strongly affected by emotional arousal; the slow wave was influenced by both emotional arousal and morality, suggesting distinct moral processing at different emotional arousal levels.

  4. Relationships between M. enterolobii and F. solani: spatial and temporal dynamics in the occurrence of guava decline

    Directory of Open Access Journals (Sweden)

    Vicente Martins Gomes

    2014-08-01

    Full Text Available Guava decline, caused by the interaction between the phytonematode Meloidogyne enterolobii and the fungus Fusarium solani, has caused direct and indirect losses to the whole productive chain of guava. Aiming to understand the interaction mechanisms between M. enterolobii and F. solani, this study carried out a bioassay on guava plants with roots in two different treatments: inoculated separatelyor together with the fungus and/or nematode. The nematode parasitism not triggered an systemic effect on the plant become susceptible to root rot caused by the fungus.Therefore, it was concluded that there was a local effect of parasitism by M. enterolobii on the pathogenicity of F. solani in guava roots, making it necessary for the two pathogens to occupy the same space at the same time for occurrence of guava decline. Keywords: complex disease, Fusarium solani, guava root-knot nematode, Meloidogyne enterolobii, Psidium guajava. Cite as Gomes VM, Souza RM, Almeida AM, Dolinski C. Relationships between M. enterolobii and F. solani: spatial and temporal dynamics in the occurrence of guava decline.

  5. Spatio-Temporal Dynamics of Viruses are Differentially Affected by Parasitoids Depending on the Mode of Transmission

    Directory of Open Access Journals (Sweden)

    Elisa Viñuela

    2012-11-01

    Full Text Available Relationships between agents in multitrophic systems are complex and very specific. Insect-transmitted plant viruses are completely dependent on the behaviour and distribution patterns of their vectors. The presence of natural enemies may directly affect aphid behaviour and spread of plant viruses, as the escape response of aphids might cause a potential risk for virus dispersal. The spatio-temporal dynamics of Cucumber mosaic virus (CMV and Cucurbit aphid-borne yellows virus (CABYV, transmitted by Aphis gossypii in a non-persistent and persistent manner, respectively, were evaluated at short and long term in the presence and absence of the aphid parasitoid, Aphidius colemani. SADIE methodology was used to study the distribution patterns of both the virus and its vector, and their degree of association. Results suggested that parasitoids promoted aphid dispersion at short term, which enhanced CMV spread, though consequences of parasitism suggest potential benefits for disease control at long term. Furthermore, A. colemani significantly limited the spread and incidence of the persistent virus CABYV at long term. The impact of aphid parasitoids on the dispersal of plant viruses with different transmission modes is discussed.

  6. Correlated continuous time random walks: combining scale-invariance with long-range memory for spatial and temporal dynamics

    International Nuclear Information System (INIS)

    Schulz, Johannes H P; Chechkin, Aleksei V; Metzler, Ralf

    2013-01-01

    Standard continuous time random walk (CTRW) models are renewal processes in the sense that at each jump a new, independent pair of jump length and waiting time are chosen. Globally, anomalous diffusion emerges through scale-free forms of the jump length and/or waiting time distributions by virtue of the generalized central limit theorem. Here we present a modified version of recently proposed correlated CTRW processes, where we incorporate a power-law correlated noise on the level of both jump length and waiting time dynamics. We obtain a very general stochastic model, that encompasses key features of several paradigmatic models of anomalous diffusion: discontinuous, scale-free displacements as in Lévy flights, scale-free waiting times as in subdiffusive CTRWs, and the long-range temporal correlations of fractional Brownian motion (FBM). We derive the exact solutions for the single-time probability density functions and extract the scaling behaviours. Interestingly, we find that different combinations of the model parameters lead to indistinguishable shapes of the emerging probability density functions and identical scaling laws. Our model will be useful for describing recent experimental single particle tracking data that feature a combination of CTRW and FBM properties. (paper)

  7. Early developmental, temperamental and educational problems in 'substance use disorder' patients with and without ADHD. Does ADHD make a difference?

    Science.gov (United States)

    Skutle, Arvid; Bu, Eli Torild Hellandsjø; Jellestad, Finn Konow; van Emmerik-van Oortmerssen, Katelijne; Dom, Geert; Verspreet, Sofie; Carpentier, Pieter Jan; Ramos-Quiroga, Josep Antoni; Franck, Johan; Konstenius, Maija; Kaye, Sharlene; Demetrovics, Zsolt; Barta, Csaba; Fatséas, Melina; Auriacombe, Marc; Johnson, Brian; Faraone, Stephen V; Levin, Frances R; Allsop, Steve; Carruthers, Susan; Schoevers, Robert A; Koeter, Maarten W J; van den Brink, Wim; Moggi, Franz; Møller, Merete; van de Glind, Geurt

    2015-12-01

    The prevalence of ADHD among patients with substance use disorder (SUD) is substantial. This study addressed the following research questions: Are early developmental, temperamental and educational problems overrepresented among SUD patients with ADHD compared to SUD patients without ADHD? Do this comorbid group receive early help for their ADHD, and are there signs of self-medicating with illicit central stimulants? An international, multi-centre cross-sectional study was carried out involving seven European countries, with 1205 patients in treatment for SUD. The mean age was 40 years and 27% of the sample was female. All participants were interviewed with the Mini International Neuropsychiatric Interview Plus and the Conners' Adult ADHD Diagnostic Interview for DSM-IV. SUD patients with ADHD ( n  = 196; 16.3% of the total sample) had a significantly slower infant development than SUD patients without ADHD ( n  = 1,009; 83.4%), had greater problems controlling their temperament, and had lower educational attainment. Only 24 (12%) of the current ADHD positive patients had been diagnosed and treated during childhood and/or adolescence. Finally, SUD patients with ADHD were more likely to have central stimulants or cannabis as their primary substance of abuse, whereas alcohol use was more likely to be the primary substance of abuse in SUD patients without ADHD. The results emphasize the importance of early identification of ADHD and targeted interventions in the health and school system, as well as in the addiction field.

  8. A New Approach to Measuring Individual Differences in Sensitivity to Facial Expressions: Influence of Temperamental Shyness and Sociability

    Directory of Open Access Journals (Sweden)

    Xiaoqing eGao

    2014-02-01

    Full Text Available To examine individual differences in adults’ sensitivity to facial expressions, we used a novel method that has proved revealing in studies of developmental change. Using static faces morphed to show different intensities of facial expressions, we calculated two measures: (1 the threshold to detect that a low intensity facial expression is different from neutral, and (2 accuracy in recognizing the specific facial expression in faces above the detection threshold. We conducted two experiments with young adult females varying in reported temperamental shyness and sociability - the former trait is known to influence the recognition of facial expressions during childhood. In both experiments, the measures had good split half reliability. Because shyness was significantly negatively correlated with sociability, we used partial correlations to examine the relation of each to sensitivity to facial expression. Sociability was negatively related to threshold to detect fear (Experiment 1 and to misidentify fear as another expression or happy expressions as fear (Experiment 2. Both patterns are consistent with hypervigilance by less sociable individuals. Shyness was positively related to misidentification of fear as another emotion (Experiment 2, a pattern consistent with a history of avoidance. We discuss the advantages and limitations of this new approach for studying individual differences in sensitivity to facial expression.

  9. Cortical Activation during a Cognitive Challenge in Patients with Chronic Temporal Lobe Epilepsy—A Dynamic SPECT Study

    Directory of Open Access Journals (Sweden)

    P. J. Kirkpatrick

    1993-01-01

    Full Text Available In a pilot group of six patients suffering from chronic temporal lobe epilepsy, single photon emission computerized tomography (SPECT has been used to image the changes in relative cerebral blood flow between rest (static scan and conditions of cognitive activation (activated scan. The cognitive challenge used during activation comprised a test of word memory, and the performance was expressed as a word memory score (WMS for each individual. An activation index (AI was calculated from the mean normalized density counts in specific regions of interest (ROIs, and values obtained were analysed for correlation with the WMS. The mean AI was increased significantly in the right lateral temporal cortex, the right and left inferior frontal regions, the left temporal pole, and the right medial temporal cortex. A positive correlation with the WMS was found in the medial temporal cortices, and this relationship was significant for the right medial temporal ROI.

  10. Dynamics of metallic contaminants at a basin scale--Spatial and temporal reconstruction from four sediment cores (Loire fluvial system, France).

    Science.gov (United States)

    Dhivert, E; Grosbois, C; Courtin-Nomade, A; Bourrain, X; Desmet, M

    2016-01-15

    From the 19th century, the Loire basin (France) presents potentially pollutant activities such as mining and heavy industries. This paper shows spatio-temporal distribution of trace elements in sediments at a basin-scale, based on a comparison of archived temporal signals recorded in four sedimentary cores. Anthropogenic sources contributing to sediment contamination are also characterized, using geochemical signatures recorded in river bank sediments of the most industrialized tributaries. This study highlights upstream-downstream differences concerning recorded contamination phases in terms of spatial influence and temporality of archiving processes. Such differences were related to (i) various spatial influences of contamination sources and (ii) polluted sediments dispersion controlled by transport capacity of metal-carrier phases and hydrosedimentary dynamics. Copyright © 2015 Elsevier B.V. All rights reserved.

  11. Spatial-temporal bio-optical classification of dynamic semi-estuarine waters in western North America

    Science.gov (United States)

    Phillips, Stephen Robert; Costa, Maycira

    2017-12-01

    The use of standard ocean colour reflectance based algorithms to derive surface chlorophyll may have limited applicability for optically dynamic coastal waters due to the pre-defined coefficients based on global datasets. Reflectance based algorithms adjusted to regional optical water characteristics are a promising alternative. A class-based definition of optically diverse coastal waters was investigated as a first step towards the development of temporal and spatial constrained reflectance based algorithms for optically variable coastal waters. A large set of bio-optical data were collected as part of five research cruises and bi-weekly trips aboard a ship of opportunity in the west coast of Canada, to assess the spatial and temporal variability of above-water reflectance in this contrasted coastal environment. To accomplish this, in situ biophysical and optical measurements were collected in conjunction with above-water hyperspectral remote sensing reflectance (Rrs) at 145 stations. The concentrations of measured biophysical data varied considerably; chlorophyll a (Chla) (mean = 1.64, range: 0.10-7.20 μg l-1), total suspended matter (TSM) (3.09, 0.82-20.69 mg l-1), and absorption by chromophoric dissolved organic matter (CDOM) (acdom(443 nm)) (0.525, 0.007-3.072 m-1), thus representing the spatio-temporal variability of the Salish Sea. Optically, a similar large range was also found; particulate scattering (bp(650 nm)) (1.316, 0.250-7.450 m-1), particulate backscattering (bbp(650 nm)) (0.022, 0.005-0.097 m-1), total beam attenuation coefficient (ct(650)) (1.675, 0.371-9.537 m-1) and particulate absorption coefficient (ap(650 nm)) (0.345, 0.048-2.020 m-1). An empirical orthogonal function (EOF) analysis revealed that Rrs variability was highly correlated to bp (r = 0.90), bbp (r = 0.82) and concentration of TSM (r = 0.80), which highlighted the dominant role of water turbidity in this region. Hierarchical clustering analysis was applied to the normalized Rrs

  12. The spatio-temporal dynamic pattern of rural domestic solid waste discharge of China and its challenges.

    Science.gov (United States)

    Tian, Guangjin; Kong, Lingqiang; Liu, Xiaojuan; Yuan, Wenping

    2018-04-01

    At present, construction of rural domestic waste treatment facilities is seriously lagging, and in many cases, treatment facilities do not yet exist in some villages of China. Serious rural waste pollution has not only impacted the quality of surface water and groundwater but also the atmosphere and the living environment of farmers of China. There are relatively few studies of rural domestic waste pollution, especially with respect to the spatio-temporal dynamic pattern of rural domestic waste discharge. Using survey data and income per capita, we calculated rural domestic waste discharge per capita per day. From this, we calculated provincial rural domestic waste discharge. According to our study, rural domestic waste discharge was 1.42 × 10 8 t/year in 2000. This number increased to 2.3 × 10 8 t/year in 2006 and to 2.47 × 10 8 t/year in 2010. Rural domestic waste increased dramatically while the actual rural population and the proportion of the rural population declined. When examining the eight regions, the rural domestic waste discharge of northeastern China, Qinghai-Tibet, middle China, and southwestern China had increased dramatically, while that of northern China, southern China, and eastern China increased relatively slowly. The economies of northern China, southern China, and eastern China are more developed; their rural domestic waste discharge has been high since 2000 and has continued to increase slowly. In northeastern China, Qinghai-Tibet, middle China, and southwestern China, rural domestic waste discharge was low in 2000; however, in the ten-year period from 2000 to 2010, their rural domestic waste discharge increased dramatically.

  13. Temporal Dynamics of Health and Well-Being: A Crowdsourcing Approach to Momentary Assessments and Automated Generation of Personalized Feedback.

    Science.gov (United States)

    van der Krieke, Lian; Blaauw, Frank J; Emerencia, Ando C; Schenk, Hendrika M; Slaets, Joris P J; Bos, Elisabeth H; de Jonge, Peter; Jeronimus, Bertus F

    Recent developments in research and mobile health enable a quantitative idiographic approach in health research. The present study investigates the potential of an electronic diary crowdsourcing study in the Netherlands for (1) large-scale automated self-assessment for individual-based health promotion and (2) enabling research at both the between-persons and within-persons level. To illustrate the latter, we examined between-persons and within-persons associations between somatic symptoms and quality of life. A website provided the general Dutch population access to a 30-day (3 times a day) diary study assessing 43 items related to health and well-being, which gave participants personalized feedback. Associations between somatic symptoms and quality of life were examined with a linear mixed model. A total of 629 participants completed 28,430 assessments, with a mean (SD) of 45 (32) assessments per participant. Most participants (n = 517 [82%]) were women and 531 (84%) had high education. Almost 40% of the participants (n = 247) completed enough assessments (t = 68) to generate personalized feedback including temporal dynamics between well-being, health behavior, and emotions. Substantial between-person variability was found in the within-person association between somatic symptoms and quality of life. We successfully built an application for automated diary assessments and personalized feedback. The application was used by a sample of mainly highly educated women, which suggests that the potential of our intensive diary assessment method for large-scale health promotion is limited. However, a rich data set was collected that allows for group-level and idiographic analyses that can shed light on etiological processes and may contribute to the development of empirical-based health promotion solutions.

  14. Analysis of spatial and temporal dynamics of xylem refilling in Acer rubrum L. using magnetic resonance imaging (MRI.

    Directory of Open Access Journals (Sweden)

    Maciej Andrzej Zwieniecki

    2013-07-01

    Full Text Available We report results of an analysis of embolism formation and subsequent refilling observed in stems of Acer rubrum L. using magnetic resonance imaging (MRI. MRI is one of the very few techniques that can provide direct non-destructive observations of the water content within opaque biological materials at a micrometer resolution. Thus, it has been used to determine temporal dynamics and water distributions within xylem tissue. In this study, we found good agreement between MRI measures of pixel brightness to assess xylem liquid water content and the percent loss in hydraulic conductivity (PLC in response to water stress (P50 values of 2.51 and 2.70 for MRI and PLC, respectively. These data provide strong support that pixel brightness is well correlated to PLC and can be used as a proxy of PLC even when single vessels cannot be resolved on the image. Pressure induced embolism in moderately stressed plants resulted in initial drop of pixel brightness. This drop was followed by brightness gain over 100 minutes following pressure application suggesting that plants can restore water content in stem after induced embolism. This recovery was limited only to current year wood ring; older wood did not show signs of recovery within the length of experiment (16 hours. In vivo MRI observations of the xylem of moderately stressed (~-0.5 MPa A. rubrum stems revealed evidence of a spontaneous embolism formation followed by rapid refilling (~30 minutes. Spontaneous (not induced embolism formation was observed only once, despite over 60 hours of continuous MRI observations made on several plants. Thus this observation provide evidence for presence of naturally occurring embolism-refilling cycle in A. rubrum, but it is impossible to infer any conclusions in relation to its frequency in nature.

  15. Analysis of spatial and temporal dynamics of xylem refilling in Acer rubrum L. using magnetic resonance imaging.

    Science.gov (United States)

    Zwieniecki, Maciej A; Melcher, Peter J; Ahrens, Eric T

    2013-01-01

    We report results of an analysis of embolism formation and subsequent refilling observed in stems of Acer rubrum L. using magnetic resonance imaging (MRI). MRI is one of the very few techniques that can provide direct non-destructive observations of the water content within opaque biological materials at a micrometer resolution. Thus, it has been used to determine temporal dynamics and water distributions within xylem tissue. In this study, we found good agreement between MRI measures of pixel brightness to assess xylem liquid water content and the percent loss in hydraulic conductivity (PLC) in response to water stress (P50 values of 2.51 and 2.70 for MRI and PLC, respectively). These data provide strong support that pixel brightness is well correlated to PLC and can be used as a proxy of PLC even when single vessels cannot be resolved on the image. Pressure induced embolism in moderately stressed plants resulted in initial drop of pixel brightness. This drop was followed by brightness gain over 100 min following pressure application suggesting that plants can restore water content in stem after induced embolism. This recovery was limited only to current-year wood ring; older wood did not show signs of recovery within the length of experiment (16 h). In vivo MRI observations of the xylem of moderately stressed (~-0.5 MPa) A. rubrum stems revealed evidence of a spontaneous embolism formation followed by rapid refilling (~30 min). Spontaneous (not induced) embolism formation was observed only once, despite over 60 h of continuous MRI observations made on several plants. Thus this observation provide evidence for the presence of naturally occurring embolism-refilling cycle in A. rubrum, but it is impossible to infer any conclusions in relation to its frequency in nature.

  16. Tracing the spatio-temporal dynamics of endangered fin whales (Balaenoptera physalus) within baleen whale (Mysticeti) lineages: a mitogenomic perspective.

    Science.gov (United States)

    Yu, Jihyun; Nam, Bo-Hye; Yoon, Joon; Kim, Eun Bae; Park, Jung Youn; Kim, Heebal; Yoon, Sook Hee

    2017-12-01

    To explore the spatio-temporal dynamics of endangered fin whales (Balaenoptera physalus) within the baleen whale (Mysticeti) lineages, we analyzed 148 published mitochondrial genome sequences of baleen whales. We used a Bayesian coalescent approach as well as Bayesian inferences and maximum likelihood methods. The results showed that the fin whales had a single maternal origin, and that there is a significant correlation between geographic location and evolution of global fin whales. The most recent common female ancestor of this species lived approximately 9.88 million years ago (Mya). Here, North Pacific fin whales first appeared about 7.48 Mya, followed by a subsequent divergence in Southern Hemisphere approximately 6.63 Mya and North Atlantic about 4.42 Mya. Relatively recently, approximately 1.76 and 1.42 Mya, there were two additional occurrences of North Pacific populations; one originated from the Southern Hemisphere and the other from an uncertain location. The evolutionary rate of this species was 1.002 × 10 -3 substitutions/site/My. Our Bayesian skyline plot illustrates that the fin whale population has the rapid expansion event since ~ 2.5 Mya, during the Quaternary glaciation stage. Additionally, this study indicates that the fin whale has a sister group relationship with humpback whale (Meganoptera novaeangliae) within the baleen whale lineages. Of the 16 genomic regions, NADH5 showed the most powerful signal for baleen whale phylogenetics. Interestingly, fin whales have 16 species-specific amino acid residues in eight mitochondrial genes: NADH2, COX2, COX3, ATPase6, ATPase8, NADH4, NADH5, and Cytb.

  17. Spatio-Temporal Dynamics of Asymptomatic Malaria: Bridging the Gap Between Annual Malaria Resurgences in a Sahelian Environment.

    Science.gov (United States)

    Coulibaly, Drissa; Travassos, Mark A; Tolo, Youssouf; Laurens, Matthew B; Kone, Abdoulaye K; Traore, Karim; Sissoko, Mody; Niangaly, Amadou; Diarra, Issa; Daou, Modibo; Guindo, Boureima; Rebaudet, Stanislas; Kouriba, Bourema; Dessay, Nadine; Piarroux, Renaud; Plowe, Christopher V; Doumbo, Ogobara K; Thera, Mahamadou A; Gaudart, Jean

    2017-12-01

    In areas of seasonal malaria transmission, the incidence rate of malaria infection is presumed to be near zero at the end of the dry season. Asymptomatic individuals may constitute a major parasite reservoir during this time. We conducted a longitudinal analysis of the spatio-temporal distribution of clinical malaria and asymptomatic parasitemia over time in a Malian town to highlight these malaria transmission dynamics. For a cohort of 300 rural children followed over 2009-2014, periodicity and phase shift between malaria and rainfall were determined by spectral analysis. Spatial risk clusters of clinical episodes or carriage were identified. A nested-case-control study was conducted to assess the parasite carriage factors. Malaria infection persisted over the entire year with seasonal peaks. High transmission periods began 2-3 months after the rains began. A cluster with a low risk of clinical malaria in the town center persisted in high and low transmission periods. Throughout 2009-2014, cluster locations did not vary from year to year. Asymptomatic and gametocyte carriage were persistent, even during low transmission periods. For high transmission periods, the ratio of asymptomatic to clinical cases was approximately 0.5, but was five times higher during low transmission periods. Clinical episodes at previous high transmission periods were a protective factor for asymptomatic carriage, but carrying parasites without symptoms at a previous high transmission period was a risk factor for asymptomatic carriage. Stable malaria transmission was associated with sustained asymptomatic carriage during dry seasons. Control strategies should target persistent low-level parasitemia clusters to interrupt transmission.

  18. Long-term temporal and spatial dynamics of food availability for endangered mountain gorillas in Volcanoes National Park, Rwanda.

    Science.gov (United States)

    Grueter, Cyril C; Ndamiyabo, Ferdinand; Plumptre, Andrew J; Abavandimwe, Didier; Mundry, Roger; Fawcett, Katie A; Robbins, Martha M

    2013-03-01

    Monitoring temporal and spatial changes in the resource availability of endangered species contributes to their conservation. The number of critically endangered mountain gorillas (Gorilla beringei beringei) in the Virunga Volcano population has doubled over the past three decades, but no studies have examined how food availability has changed during that period. First, we assessed if the plant species consumed by the gorillas have changed in abundance and distribution during the past two decades. In 2009-2010, we replicated a study conducted in 1988-1989 by measuring the frequency, density, and biomass of plant species consumed by the gorillas in 496 plots (ca. 6 km(2)) in the Karisoke study area in Volcanoes National Park, Rwanda. We expected to observe a decreased presence of major gorilla food plants as a likely result of density-dependent overharvesting by gorillas. Among the five most frequently consumed species (composing approximately 70% of the gorilla's diet, excluding bamboo), two have decreased in availability and abundance, while three have increased. Some species have undergone shifts in their altitudinal distribution, possibly due to regional climatic changes. Second, we made baseline measurements of food availability in a larger area currently utilized by the gorillas. In the extended sampling (n = 473 plots) area (ca. 25 km(2) ), of the five most frequently consumed species, two were not significantly different in frequency from the re-sampled area, while two occurred significantly less frequently, and one occurred significantly more frequently. We discuss the potential impact of gorilla-induced herbivory on changes of vegetation abundance. The changes in the species most commonly consumed by the gorillas could affect their nutrient intake and stresses the importance of monitoring the interrelation among plant population dynamics, species density, and resource use. © 2012 Wiley Periodicals, Inc.

  19. Temporal dynamics and impact of climate factors on the incidence of zoonotic cutaneous leishmaniasis in central Tunisia.

    Directory of Open Access Journals (Sweden)

    Amine Toumi

    Full Text Available Old world Zoonotic Cutaneous Leishmaniasis (ZCL is a vector-borne human disease caused by Leishmania major, a unicellular eukaryotic parasite transmitted by pool blood-feeding sand flies mainly to wild rodents, such as Psammomys obesus. The human beings who share the rodent and sand fly habitats can be subverted as both sand fly blood resource. ZCL is endemic in the Middle East, Central Asia, Subsaharan and North Africa. Like other vector-borne diseases, the incidence of ZCL displayed by humans varies with environmental and climate factors. However, so far no study has addressed the temporal dynamics or the impact of climate factors on the ZCL risk.Seasonality during the same epidemiologic year and interval between ZCL epidemics ranging from 4 to 7 years were demonstrated. Models showed that ZCL incidence is raising i by 1.8% (95% confidence intervals CI:0.0-3.6% when there is 1 mm increase in the rainfall lagged by 12 to 14 months ii by 5.0% (95% CI: 0.8-9.4% when there is a 1% increase in humidity from July to September in the same epidemiologic year.Higher rainfall is expected to result in increased density of chenopods, a halophytic plant that constitutes the exclusive food of Psammomys obesus. Consequently, following a high density of Psammomys obesus, the pool of Leishmania major transmissible from the rodents to blood-feeding female sand flies could lead to a higher probability of transmission to humans over the next season. These findings provide the evidence that ZCL is highly influenced by climate factors that could affect both Psammomys obesus and the sand fly population densities.

  20. Temporal dynamics of soil organic carbon after land-use change in the temperate zone – carbon response functions as a model approach

    DEFF Research Database (Denmark)

    Poeplau, Christopher; Don, Axel; Vesterdal, Lars

    2011-01-01

    Land-use change (LUC) is a major driving factor for the balance of soil organic carbon (SOC) stocks and the global carbon cycle. The temporal dynamic of SOC after LUC is especially important in temperate systems with a long reaction time. On the basis of 95 compiled studies covering 322 sites...... approach, the developed CRFs provide an easily applicable tool to estimate SOC stock changes after LUC to improve greenhouse gas reporting in the framework of UNFCCC....

  1. Developing Baltic cod recruitment models I : Resolving spatial and temporal dynamics of spawning stock and recruitment for cod, herring, and sprat

    DEFF Research Database (Denmark)

    Köster, Fritz; Möllmann, C.; Neuenfeldt, Stefan

    2001-01-01

    The Baltic Sea comprises a heterogeneous oceanographic environment influencing the spatial and temporal potential for reproductive success of cod (Gadus morhua) and sprat (Sprattus sprattus) in the different spawning basins. Hence, to quantify stock and recruitment dynamics, it is necessary......-disaggregated multispecies virtual population analyses (MSVPA) were performed for interacting species cod, herring (Clupea harengus), and sprat in the different subdivisions of the Central Baltic. The MSVPA runs revealed distinct spatial trends in population abundance, spawning biomass, recruitment, and predation...

  2. Real-time Fatigue and Free-Living Physical Activity in Hematopoietic Stem Cell Transplantation Cancer Survivors and Healthy Controls: A Preliminary Examination of the Temporal, Dynamic Relationship.

    Science.gov (United States)

    Hacker, Eileen Danaher; Kim, Inah; Park, Chang; Peters, Tara

    Fatigue and physical inactivity, critical problems facing cancer survivors, impact overall health and functioning. Our group designed a novel methodology to evaluate the temporal, dynamic patterns in real-world settings. Using real-time technology, the temporal, dynamic relationship between real-time fatigue and free-living is described and compared in cancer survivors who were treated with hematopoietic stem cell transplantation (n = 25) and age- and gender-matched healthy controls (n = 25). Subjects wore wrist actigraphs on their nondominant hand to assess free-living physical activity, measured in 1-minute epochs, over 7 days. Subjects entered real-time fatigue assessments directly into the subjective event marker of the actigraph 5 times per day. Running averages of mean 1-minute activity counts 30, 60, and 120 minutes before and after each real-time fatigue score were correlated with real-time fatigue using generalized estimating equations, RESULTS:: A strong inverse relationship exists between real-time fatigue and subsequent free-living physical activity. This inverse relationship suggests that increasing real-time fatigue limits subsequent physical activity (B range= -0.002 to -0.004; P < .001). No significant differences in the dynamic patterns of real-time fatigue and free-living physical activity were found between groups. To our knowledge, this is the first study to document the temporal and potentially causal relationship between real-time fatigue and free-living physical activity in real-world setting. These findings suggest that fatigue drives the subsequent physical activity and the relationship may not be bidirectional. Understanding the temporal, dynamic relationship may have important health implications for developing interventions to address fatigue in cancer survivors.

  3. Imaging the spatio-temporal dynamics of supragranular activity in the rat somatosensory cortex in response to stimulation of the paws.

    Directory of Open Access Journals (Sweden)

    M L Morales-Botello

    Full Text Available We employed voltage-sensitive dye (VSD imaging to investigate the spatio-temporal dynamics of the responses of the supragranular somatosensory cortex to stimulation of the four paws in urethane-anesthetized rats. We obtained the following main results. (1 Stimulation of the contralateral forepaw evoked VSD responses with greater amplitude and smaller latency than stimulation of the contralateral hindpaw, and ipsilateral VSD responses had a lower amplitude and greater latency than contralateral responses. (2 While the contralateral stimulation initially activated only one focus, the ipsilateral stimulation initially activated two foci: one focus was typically medial to the focus activated by contralateral stimulation and was stereotaxically localized in the motor cortex; the other focus was typically posterior to the focus activated by contralateral stimulation and was stereotaxically localized in the somatosensory cortex. (3 Forepaw and hindpaw somatosensory stimuli activated large areas of the sensorimotor cortex, well beyond the forepaw and hindpaw somatosensory areas of classical somatotopic maps, and forepaw stimuli activated larger cortical areas with greater activation velocity than hindpaw stimuli. (4 Stimulation of the forepaw and hindpaw evoked different cortical activation dynamics: forepaw responses displayed a clear medial directionality, whereas hindpaw responses were much more uniform in all directions. In conclusion, this work offers a complete spatio-temporal map of the supragranular VSD cortical activation in response to stimulation of the paws, showing important somatotopic differences between contralateral and ipsilateral maps as well as differences in the spatio-temporal activation dynamics in response to forepaw and hindpaw stimuli.

  4. Temperamental dimensions of the TEMPS-A in females with co-morbid bipolar disorder and bulimia.

    Science.gov (United States)

    Rybakowski, Janusz K; Kaminska, Katarzyna; Charytonik, Jolanta; Akiskal, Kareen K; Akiskal, Hagop S

    2014-08-01

    We investigated the effect of co-morbid bipolar disorder and bulimia on temperamental dimensions measured by TEMPS-A, relative to "pure" bulimia and "pure" bipolar disorder, in female patients. The study was performed on 47 patients with bipolar disorder (BD) with a mean age of 36±10 years, 96 patients with bulimia or bulimic type of anorexia, mean age 26±9 years and 50 control healthy females (HC), mean age 29±6 years. Among bulimic patients, a group of 68 subjects with co-morbid bulimia with bipolarity (BD+B) was identified, based on positive score of the Mood Disorder Questionnaire (MDQ). The TEMPS-A questionnaire, 110 questions version, has been used, evaluating five temperament domains: depressive, cyclothymic, hyperthymic, irritable and anxious. Parametric analysis was performed for 4 groups (BD, "pure" bulimia (PB), BD+B and HC), with 28 subjects randomly chosen from each group, using analysis of variance and cluster analysis. All clinical groups significantly differed from control group by having higher scores of depressive, cyclothymic, irritable and anxious temperaments and lower of hyperthymic one. Among patients, significantly higher scores of cyclothymic and irritable temperaments were found in BD+B compared to both PB and BD. These differences were also reflected in cluster analysis, where two clusters were identified. Bipolarity in bulimic patients assessed only by the MDQ. These results show that co-morbid bulimia and bipolar disorder is characterized by extreme dimensions of both cyclothymic and irritable temperaments, significantly higher than each single diagnosis. Possible clinical implications of such fact are discussed. Copyright © 2014 Elsevier B.V. All rights reserved.

  5. Time Series Remote Sensing in Monitoring the Spatio-Temporal Dynamics of Plant Invasions: A Study of Invasive Saltcedar (Tamarix Spp.)

    Science.gov (United States)

    Diao, Chunyuan

    In today's big data era, the increasing availability of satellite and airborne platforms at various spatial and temporal scales creates unprecedented opportunities to understand the complex and dynamic systems (e.g., plant invasion). Time series remote sensing is becoming more and more important to monitor the earth system dynamics and interactions. To date, most of the time series remote sensing studies have been conducted with the images acquired at coarse spatial scale, due to their relatively high temporal resolution. The construction of time series at fine spatial scale, however, is limited to few or discrete images acquired within or across years. The objective of this research is to advance the time series remote sensing at fine spatial scale, particularly to shift from discrete time series remote sensing to continuous time series remote sensing. The objective will be achieved through the following aims: 1) Advance intra-annual time series remote sensing under the pure-pixel assumption; 2) Advance intra-annual time series remote sensing under the mixed-pixel assumption; 3) Advance inter-annual time series remote sensing in monitoring the land surface dynamics; and 4) Advance the species distribution model with time series remote sensing. Taking invasive saltcedar as an example, four methods (i.e., phenological time series remote sensing model, temporal partial unmixing method, multiyear spectral angle clustering model, and time series remote sensing-based spatially explicit species distribution model) were developed to achieve the objectives. Results indicated that the phenological time series remote sensing model could effectively map saltcedar distributions through characterizing the seasonal phenological dynamics of plant species throughout the year. The proposed temporal partial unmixing method, compared to conventional unmixing methods, could more accurately estimate saltcedar abundance within a pixel by exploiting the adequate temporal signatures of

  6. Temporal Glare

    DEFF Research Database (Denmark)

    Ritschel, Tobias; Ihrke, Matthias; Frisvad, Jeppe Revall

    2009-01-01

    Glare is a consequence of light scattered within the human eye when looking at bright light sources. This effect can be exploited for tone mapping since adding glare to the depiction of high-dynamic range (HDR) imagery on a low-dynamic range (LDR) medium can dramatically increase perceived contra...... to initially static HDR images. By conducting psychophysical studies, we validate that our method improves perceived brightness and that dynamic glare-renderings are often perceived as more attractive depending on the chosen scene.......Glare is a consequence of light scattered within the human eye when looking at bright light sources. This effect can be exploited for tone mapping since adding glare to the depiction of high-dynamic range (HDR) imagery on a low-dynamic range (LDR) medium can dramatically increase perceived contrast....... Even though most, if not all, subjects report perceiving glare as a bright pattern that fluctuates in time, up to now it has only been modeled as a static phenomenon. We argue that the temporal properties of glare are a strong means to increase perceived brightness and to produce realistic...

  7. Investigating the relationship between subjective drug craving and temporal dynamics of the default mode network, executive control network, and salience network in methamphetamine dependents using rsfMRI

    Science.gov (United States)

    Soltanian-Zadeh, Somayyeh; Hossein-Zadeh, Gholam-Ali; Shahbabaie, Alireza; Ekhtiari, Hamed

    2016-03-01

    Resting state functional connectivity (rsFC) studies using fMRI provides a great deal of knowledge on the spatiotemporal organization of the brain. The relationships between and within a number of resting state functional networks, namely the default mode network (DMN), salience network (SN) and executive control network (ECN) have been intensely studied in basic and clinical cognitive neuroscience [1]. However, the presumption of spatial and temporal stationarity has mostly restricted the assessment of rsFC [1]. In this study, sliding window correlation analysis and k-means clustering were exploited to examine the temporal dynamics of rsFC of these three networks in 24 abstinent methamphetamine dependents. Afterwards, using canonical correlation analysis (CCA) the possible relationship between the level of self-reported craving and the temporal dynamics was examined. Results indicate that the rsFC transits between 6 discrete "FC states" in the meth dependents. CCA results show that higher levels of craving are associated with higher probability of transiting from state 4 to 6 (positive FC of DMN-ECN getting weak and negative FC of DMN-SN appearing) and staying in state 4 (positive FC of DMN-ECN), lower probability of staying in state 2 (negative FC of DMN-ECN), transiting from state 4 to 2 (change of positive FC of DMN-ECN to negative FC), and transiting from state 3 to 5 (appearance of negative FC of DMN-SN and positive FC of DMN-ECN with the presence of negative FC of SN-ECN). Quantitative measures of temporal dynamics in large-scale brain networks could bring new added values to increase potentials for applications of rsfMRI in addiction medicine.

  8. Temporal dynamics of plant succession in abandoned field in Mediterranean mountain areas: farming terraces and sloping fields (Iberian System, Spain)

    Science.gov (United States)

    Nadal-Romero, Estela; Errea, Paz; Lasanta, Teodoro

    2017-04-01

    by the DESEMON and ESPAS projects (CGL2014-52135-C3-3-R and CGL2015-65569-R, funded by the MINECO-FEDER). The "Geomorphology and Global Change" and the "Climate, water, global change and natural systems" research groups were financed by the Aragón Government and the European Social Fund (ESF-FSE). Estela Nadal-Romero was the recipient of a "Ramón y Cajal" postdoctoral contract (Spanish Ministry of Economy and Competitiveness). References Burel, F. & Baudry, J. (2002): Ecología del paisaje. Conceptos, métodos y aplicaciones. Ediciones Mundi-Prensa: 353 pp., Madrid. Kouba, Y. & Alados, C.L. (2012): Spatio-temporal dynamics of Quercus faginea forest in the Spanish Central Pre-Pyrenees. European Journal of Forest Research, 131: 369-379.

  9. Spatial and temporal dynamics of organohalide-respiring bacteria in a heterogeneous PCE-DNAPL source zone.

    Science.gov (United States)

    Cápiro, Natalie L; Löffler, Frank E; Pennell, Kurt D

    2015-11-01

    Effective treatment of sites contaminated with dense non-aqueous phase liquids (DNAPLs) requires detailed understanding of the microbial community responses to changes in source zone strength and architecture. Changes in the spatial and temporal distributions of the organohalide-respiring Dehalococcoides mccartyi (Dhc) strains and Geobacter lovleyi strain SZ (GeoSZ) were examined in a heterogeneous tetrachloroethene- (PCE-) DNAPL source zone within a two-dimensional laboratory-scale aquifer flow cell. As part of a combined remedy approach, flushing with 2.3 pore volumes (PVs) of 4% (w/w) solution of the nonionic, biodegradable surfactant Tween® 80 removed 55% of the initial contaminant mass, and resulted in a PCE-DNAPL distribution that contained 51% discrete ganglia and 49% pools (ganglia-to-pool ratio of 1.06). Subsequent bioaugmentation with the PCE-to-ethene-dechlorinating consortium BDI-SZ resulted in cis-1,2-dichloroethene (cis-DCE) formation after 1 PV (ca. 7 days), while vinyl chloride (VC) and ethene were detected 10 PVs after bioaugmentation. Maximum ethene yields (ca. 90 μM) within DNAPL pool and ganglia regions coincided with the detection of the vcrA reductive dehalogenase (RDase) gene that exceeded the Dhc 16S rRNA genes by 2.0±1.3 and 4.0±1.7 fold in the pool and ganglia regions, respectively. Dhc and GeoSZ cell abundance increased by up to 4 orders-of-magnitude after 28 PVs of steady-state operation, with 1 to 2 orders-of-magnitude increases observed in close proximity to residual PCE-DNAPL. These observations suggest the involvement of these dechlorinators the in observed PCE dissolution enhancements of up to 2.3 and 6.0-fold within pool and ganglia regions, respectively. Analysis of the solid and aqueous samples at the conclusion of the experiment revealed that the highest VC (≥155 μM) and ethene (≥65 μM) concentrations were measured in zones where Dhc and GeoSZ were predominately attached to the solids. These findings demonstrate

  10. Static and dynamic controls on fire activity at moderate spatial and temporal scales in the Alaskan boreal forest

    Science.gov (United States)

    Barrett, Kirsten; Loboda, Tatiana; McGuire, A. David; Genet, Hélène; Hoy, Elizabeth; Kasischke, Eric

    2016-01-01

    Wildfire, a dominant disturbance in boreal forests, is highly variable in occurrence and behavior at multiple spatiotemporal scales. New data sets provide more detailed spatial and temporal observations of active fires and the post-burn environment in Alaska. In this study, we employ some of these new data to analyze variations in fire activity by developing three explanatory models to examine the occurrence of (1) seasonal periods of elevated fire activity using the number of MODIS active fire detections data set (MCD14DL) within an 11-day moving window, (2) unburned patches within a burned area using the Monitoring Trends in Burn Severity fire severity product, and (3) short-to-moderate interval (fires using areas of burned area overlap in the Alaska Large Fire Database. Explanatory variables for these three models included dynamic variables that can change over the course of the fire season, such as weather and burn date, as well as static variables that remain constant over a fire season, such as topography, drainage, vegetation cover, and fire history. We found that seasonal periods of high fire activity are associated with both seasonal timing and aggregated weather conditions, as well as the landscape composition of areas that are burning. Important static inputs to the model of seasonal fire activity indicate that when fire weather conditions are suitable, areas that typically resist fire (e.g., deciduous stands) may become more vulnerable to burning and therefore less effective as fire breaks. The occurrence of short-to-moderate interval fires appears to be primarily driven by weather conditions, as these were the only relevant explanatory variables in the model. The unique importance of weather in explaining short-to-moderate interval fires implies that fire return intervals (FRIs) will be sensitive to projected climate changes in the region. Unburned patches occur most often in younger stands, which may be related to a greater deciduous fraction of

  11. Nonlinear spatio-temporal filtering of dynamic PET data using a four-dimensional Gaussian filter and expectation-maximization deconvolution

    International Nuclear Information System (INIS)

    Floberg, J M; Holden, J E

    2013-01-01

    We introduce a method for denoising dynamic PET data, spatio-temporal expectation-maximization (STEM) filtering, that combines four-dimensional Gaussian filtering with EM deconvolution. The initial Gaussian filter suppresses noise at a broad range of spatial and temporal frequencies and EM deconvolution quickly restores the frequencies most important to the signal. We aim to demonstrate that STEM filtering can improve variance in both individual time frames and in parametric images without introducing significant bias. We evaluate STEM filtering with a dynamic phantom study, and with simulated and human dynamic PET studies of a tracer with reversible binding behaviour, [C-11]raclopride, and a tracer with irreversible binding behaviour, [F-18]FDOPA. STEM filtering is compared to a number of established three and four-dimensional denoising methods. STEM filtering provides substantial improvements in variance in both individual time frames and in parametric images generated with a number of kinetic analysis techniques while introducing little bias. STEM filtering does bias early frames, but this does not affect quantitative parameter estimates. STEM filtering is shown to be superior to the other simple denoising methods studied. STEM filtering is a simple and effective denoising method that could be valuable for a wide range of dynamic PET applications. (paper)

  12. Brain functional connectivity changes in children that differ in impulsivity temperamental trait

    Directory of Open Access Journals (Sweden)

    Alberto eInuggi

    2014-05-01

    Full Text Available Impulsivity is a core personality trait forming part of normal behavior and contributing to adaptive functioning. However, in typically developing children, altered patterns of impulsivity constitute a risk factor for the development of behavioral problems. Since both pathological and non-pathological states are commonly characterized by continuous transitions, we used a correlative approach to investigate the potential link between personality and brain dynamics. We related brain functional connectivity of typically developing children, measured with magnetic resonance imaging at rest, with their impulsivity scores obtained from a questionnaire completed by their parents. We first looked for areas within the default mode network (DMN whose functional connectivity might be modulated by trait impulsivity. Then, we calculated the functional connectivity among these regions and the rest of the brain in order to assess if impulsivity trait altered their relationships. We found two DMN clusters located at the posterior cingulate cortex and the right angular gyrus which were negatively correlated with impulsivity scores. The whole-brain correlation analysis revealed the classic network of correlating and anti-correlating areas with respect to the DMN. The impulsivity trait modulated such pattern showing that the canonical anti-phasic relation between DMN and action-related network was reduced in high impulsive children. These results represent the first evidence that the impulsivity, measured as personality trait assessed through parents’ report, exerts a modulatory influence over the functional connectivity of resting state brain networks in typically developing children. The present study goes further to connect developmental approaches, mainly based on data collected through the use of questionnaires, and behavioral neuroscience, interested in how differences in brain structure and functions reflect in differences in behavior.

  13. Brain functional connectivity changes in children that differ in impulsivity temperamental trait.

    Science.gov (United States)

    Inuggi, Alberto; Sanz-Arigita, Ernesto; González-Salinas, Carmen; Valero-García, Ana V; García-Santos, Jose M; Fuentes, Luis J

    2014-01-01

    Impulsivity is a core personality trait forming part of normal behavior and contributing to adaptive functioning. However, in typically developing children, altered patterns of impulsivity constitute a risk factor for the development of behavioral problems. Since both pathological and non-pathological states are commonly characterized by continuous transitions, we used a correlative approach to investigate the potential link between personality and brain dynamics. We related brain functional connectivity of typically developing children, measured with magnetic resonance imaging at rest, with their impulsivity scores obtained from a questionnaire completed by their parents. We first looked for areas within the default mode network (DMN) whose functional connectivity might be modulated by trait impulsivity. Then, we calculated the functional connectivity among these regions and the rest of the brain in order to assess if impulsivity trait altered their relationships. We found two DMN clusters located at the posterior cingulate cortex and the right angular gyrus which were negatively correlated with impulsivity scores. The whole-brain correlation analysis revealed the classic network of correlating and anti-correlating areas with respect to the DMN. The impulsivity trait modulated such pattern showing that the canonical anti-phasic relation between DMN and action-related network was reduced in high impulsive chi