Sample records for naturality threshold behavior

  1. The Nature of Psychological Thresholds (United States)

    Rouder, Jeffrey N.; Morey, Richard D.


    Following G. T. Fechner (1966), thresholds have been conceptualized as the amount of intensity needed to transition between mental states, such as between a states of unconsciousness and consciousness. With the advent of the theory of signal detection, however, discrete-state theory and the corresponding notion of threshold have been discounted.…

  2. Scaling behavior of threshold epidemics (United States)

    Ben-Naim, E.; Krapivsky, P. L.


    We study the classic Susceptible-Infected-Recovered (SIR) model for the spread of an infectious disease. In this stochastic process, there are two competing mechanism: infection and recovery. Susceptible individuals may contract the disease from infected individuals, while infected ones recover from the disease at a constant rate and are never infected again. Our focus is the behavior at the epidemic threshold where the rates of the infection and recovery processes balance. In the infinite population limit, we establish analytically scaling rules for the time-dependent distribution functions that characterize the sizes of the infected and the recovered sub-populations. Using heuristic arguments, we also obtain scaling laws for the size and duration of the epidemic outbreaks as a function of the total population. We perform numerical simulations to verify the scaling predictions and discuss the consequences of these scaling laws for near-threshold epidemic outbreaks.

  3. Threshold behavior in electron-atom scattering

    International Nuclear Information System (INIS)

    Sadeghpour, H.R.; Greene, C.H.


    Ever since the classic work of Wannier in 1953, the process of treating two threshold electrons in the continuum of a positively charged ion has been an active field of study. The authors have developed a treatment motivated by the physics below the double ionization threshold. By modeling the double ionization as a series of Landau-Zener transitions, they obtain an analytical formulation of the absolute threshold probability which has a leading power law behavior, akin to Wannier's law. Some of the noteworthy aspects of this derivation are that the derivation can be conveniently continued below threshold giving rise to a open-quotes cuspclose quotes at threshold, and that on both sides of the threshold, absolute values of the cross sections are obtained

  4. Mob control models of threshold collective behavior

    CERN Document Server

    Breer, Vladimir V; Rogatkin, Andrey D


    This book presents mathematical models of mob control with threshold (conformity) collective decision-making of the agents. Based on the results of analysis of the interconnection between the micro- and macromodels of active network structures, it considers the static (deterministic, stochastic and game-theoretic) and dynamic (discrete- and continuous-time) models of mob control, and highlights models of informational confrontation. Many of the results are applicable not only to mob control problems, but also to control problems arising in social groups, online social networks, etc. Aimed at researchers and practitioners, it is also a valuable resource for undergraduate and postgraduate students as well as doctoral candidates specializing in the field of collective behavior modeling.

  5. Fuzzy Behavior Modulation with Threshold Activation for Autonomous Vehicle Navigation (United States)

    Tunstel, Edward


    This paper describes fuzzy logic techniques used in a hierarchical behavior-based architecture for robot navigation. An architectural feature for threshold activation of fuzzy-behaviors is emphasized, which is potentially useful for tuning navigation performance in real world applications. The target application is autonomous local navigation of a small planetary rover. Threshold activation of low-level navigation behaviors is the primary focus. A preliminary assessment of its impact on local navigation performance is provided based on computer simulations.

  6. Nonlinear threshold behavior during the loss of Arctic sea ice. (United States)

    Eisenman, I; Wettlaufer, J S


    In light of the rapid recent retreat of Arctic sea ice, a number of studies have discussed the possibility of a critical threshold (or "tipping point") beyond which the ice-albedo feedback causes the ice cover to melt away in an irreversible process. The focus has typically been centered on the annual minimum (September) ice cover, which is often seen as particularly susceptible to destabilization by the ice-albedo feedback. Here, we examine the central physical processes associated with the transition from ice-covered to ice-free Arctic Ocean conditions. We show that although the ice-albedo feedback promotes the existence of multiple ice-cover states, the stabilizing thermodynamic effects of sea ice mitigate this when the Arctic Ocean is ice covered during a sufficiently large fraction of the year. These results suggest that critical threshold behavior is unlikely during the approach from current perennial sea-ice conditions to seasonally ice-free conditions. In a further warmed climate, however, we find that a critical threshold associated with the sudden loss of the remaining wintertime-only sea ice cover may be likely.

  7. The impact of degree of hearing loss on auditory brainstem response predictions of behavioral thresholds. (United States)

    McCreery, Ryan W; Kaminski, Jan; Beauchaine, Kathryn; Lenzen, Natalie; Simms, Kendell; Gorga, Michael P


    Diagnosis of hearing loss and prescription of amplification for infants and young children require accurate estimates of ear- and frequency-specific behavioral thresholds based on auditory brainstem response (ABR) measurements. Although the overall relationship between ABR and behavioral thresholds has been demonstrated, the agreement is imperfect, and the accuracy of predictions of behavioral threshold based on ABR may depend on degree of hearing loss. Behavioral thresholds are lower than ABR thresholds, at least in part due to differences in calibration interacting with the effects of temporal integration, which are manifest in behavioral measurements but not ABR measurements and depend on behavioral threshold. Listeners with sensory hearing loss exhibit reduced or absent temporal integration, which could impact the relationship between ABR and behavioral thresholds as degree of hearing loss increases. The present study evaluated the relationship between ABR and behavioral thresholds in infants and children over a range of hearing thresholds, and tested an approach for adjusting the correction factor based on degree of hearing loss as estimated by ABR measurements. A retrospective review of clinical records was completed for 309 ears of 177 children with hearing thresholds ranging from normal to profound hearing loss and for whom both ABR and behavioral thresholds were available. Children were required to have the same middle ear status at both evaluations. The relationship between ABR and behavioral thresholds was examined. Factors that potentially could affect the relationship between ABR and behavioral thresholds were analyzed, including degree of hearing loss observed on the ABR, behavioral test method (visual reinforcement, conditioned play, or conventional audiometry), the length of time between ABR and behavioral assessments, and clinician-reported reliability of the behavioral assessment. Predictive accuracy of a correction factor based on the difference

  8. Behavioral determination of olfactory thresholds to amyl acetate in dogs. (United States)

    Krestel, D; Passe, D; Smith, J C; Jonsson, L


    By use of a modified conditioned suppression technique, olfactory thresholds to amyl acetate were determined for four beagle dogs. Using the same odorant and olfactometer and a similar breathing chamber, olfactory thresholds were obtained in eight human subjects. It was determined that the olfactory sensitivity of the dogs was about 2.5 log units better than that of the human subjects.

  9. Pain threshold - measure of pain sensitivity or social behavior?

    Directory of Open Access Journals (Sweden)

    Modić-Stanke Koraljka


    Full Text Available The aim was to examine the effect of the experimenter’s social status and its interaction with participant’s gender on pressure pain threshold. Both male and female students participated in the study (N = 96 and were evenly assigned into two groups which differed only in the professional status of the experimenter who was a professor (higher status in one group and a student (lower status in the other. The factorial ANOVA revealed statistically significant and large main effects of the experimenter’s status and the participants’ gender, indicating higher pain thresholds in male participants and in the higher status experimenter group. Although both males and females had higher pain thresholds when measured by a higher status experimenter, a statistically significant interaction revealed that status affected male participants more so than females. The obtained results are probably due to social behaviour, emphasizing relevance of the experimenter’s and participants’ characteristics in pain measurement.

  10. Thermal behavior of natural zeolites

    International Nuclear Information System (INIS)

    Bish, D.L.


    Thermal behavior of natural zeolites impacts their application and identification and varies significantly from zeolite to zeolite. Zeolites evolve H 2 0 upon heating, but recent data show that distinct ''types'' of water (e.g., loosely bound or tightly bound zeolitic water) do not exist. Rather water is bound primarily to extra-framework cations with a continuum of energies, giving rise to pseudocontinuous loss of water accompanied by a dynamic interaction between remaining H 2 0 molecules and extra-framework cations. These interactions in the channels of zeolites give rise to dehydration dependent on the extra-framework cation, in addition to temperature and water vapor pressure. The dehydration reaction and the extra-framework cation also affect the thermal expansion/contraction. Most zeolites undergo dehydration-induced contractions that may be anisotropic, although minor thermal expansion can be seen with some zeolites. Such contractions can be partially or completely irreversible if they involve modifications of the tetrahedral framework and/or if rehydration is sluggish. Thermally induced structural modifications are also driven initially by dehydration and the concomitant contraction and migration of extra-framework cations. Contraction is accommodated by rotations of structural units and tetrahedral cation-oxygen linkages may break. Thermal reactions that involve breaking of tetrahedral cation-oxygen bonds markedly irreversible and may be kinetically limited, producing large differences between short- and long-term heating

  11. Connections with nature and environmental behaviors. (United States)

    Geng, Liuna; Xu, Jingke; Ye, Lijuan; Zhou, Wenjun; Zhou, Kexin


    The influence of environmental attitudes on environmental behaviors has long been discussed. However, few studies have addressed the foundation of such attitudes. In the present study, we explored primitive belief underlying environmental attitudes, i.e., connections with nature, and its relationship with pro-environmental behaviors. Specifically, we used scales, a computerized Implicit Association Test, and a situational simulation experiment to examine both explicit and implicit connections with nature, both deliberate and spontaneous environmental behaviors, and to find correlations between environmental connectedness and environmental behaviors. Results showed that explicit connectedness was positively correlated with deliberate environmental behaviors, while implicit connectedness was positively correlated with spontaneous environmental behaviors. Additionally, explicit and implicit connectedness was independent of each other. In conclusion, the current study confirms the positive role played by connections with nature in promoting environmental behavior, and accordingly suggests means to encourage pro-environmental behavior by enhancing people's connectedness to nature.

  12. A note on the stochastic nature of particle cohesive force and implications to threshold friction velocity for aerodynamic dust entrainment (United States)

    There is considerable interest to determine the threshold for aeolian dust emission on Earth and Mars. Existing schemes for threshold friction velocity are all deterministic in nature, but observations show that in the dust particle size range the threshold friction velocity scatters strongly due t...

  13. On the underlying assumptions of threshold Boolean networks as a model for genetic regulatory network behavior. (United States)

    Tran, Van; McCall, Matthew N; McMurray, Helene R; Almudevar, Anthony


    Boolean networks (BoN) are relatively simple and interpretable models of gene regulatory networks. Specifying these models with fewer parameters while retaining their ability to describe complex regulatory relationships is an ongoing methodological challenge. Additionally, extending these models to incorporate variable gene decay rates, asynchronous gene response, and synergistic regulation while maintaining their Markovian nature increases the applicability of these models to genetic regulatory networks (GRN). We explore a previously-proposed class of BoNs characterized by linear threshold functions, which we refer to as threshold Boolean networks (TBN). Compared to traditional BoNs with unconstrained transition functions, these models require far fewer parameters and offer a more direct interpretation. However, the functional form of a TBN does result in a reduction in the regulatory relationships which can be modeled. We show that TBNs can be readily extended to permit self-degradation, with explicitly modeled degradation rates. We note that the introduction of variable degradation compromises the Markovian property fundamental to BoN models but show that a simple state augmentation procedure restores their Markovian nature. Next, we study the effect of assumptions regarding self-degradation on the set of possible steady states. Our findings are captured in two theorems relating self-degradation and regulatory feedback to the steady state behavior of a TBN. Finally, we explore assumptions of synchronous gene response and asynergistic regulation and show that TBNs can be easily extended to relax these assumptions. Applying our methods to the budding yeast cell-cycle network revealed that although the network is complex, its steady state is simplified by the presence of self-degradation and lack of purely positive regulatory cycles.

  14. Using natural range of variation to set decision thresholds: a case study for great plains grasslands (United States)

    Symstad, Amy J.; Jonas, Jayne L.; Edited by Guntenspergen, Glenn R.


    Natural range of variation (NRV) may be used to establish decision thresholds or action assessment points when ecological thresholds are either unknown or do not exist for attributes of interest in a managed ecosystem. The process for estimating NRV involves identifying spatial and temporal scales that adequately capture the heterogeneity of the ecosystem; compiling data for the attributes of interest via study of historic records, analysis and interpretation of proxy records, modeling, space-for-time substitutions, or analysis of long-term monitoring data; and quantifying the NRV from those data. At least 19 National Park Service (NPS) units in North America’s Great Plains are monitoring plant species richness and evenness as indicators of vegetation integrity in native grasslands, but little information on natural, temporal variability of these indicators is available. In this case study, we use six long-term vegetation monitoring datasets to quantify the temporal variability of these attributes in reference conditions for a variety of Great Plains grassland types, and then illustrate the implications of using different NRVs based on these quantities for setting management decision thresholds. Temporal variability of richness (as measured by the coefficient of variation, CV) is fairly consistent across the wide variety of conditions occurring in Colorado shortgrass prairie to Minnesota tallgrass sand savanna (CV 0.20–0.45) and generally less than that of production at the same sites. Temporal variability of evenness spans a greater range of CV than richness, and it is greater than that of production in some sites but less in other sites. This natural temporal variability may mask undesirable changes in Great Plains grasslands vegetation. Consequently, we suggest that managers consider using a relatively narrow NRV (interquartile range of all richness or evenness values observed in reference conditions) for designating a surveillance threshold, at which

  15. Crack Growth Behavior in the Threshold Region for High Cycle Fatigue Loading (United States)

    Forman, R. G.; Zanganeh, M.


    This paper describes the results of a research program conducted to improve the understanding of fatigue crack growth rate behavior in the threshold growth rate region and to answer a question on the validity of threshold region test data. The validity question relates to the view held by some experimentalists that using the ASTM load shedding test method does not produce valid threshold test results and material properties. The question involves the fanning behavior observed in threshold region of da/dN plots for some materials in which the low R-ratio data fans out from the high R-ratio data. This fanning behavior or elevation of threshold values in the low R-ratio tests is generally assumed to be caused by an increase in crack closure in the low R-ratio tests. Also, the increase in crack closure is assumed by some experimentalists to result from using the ASTM load shedding test procedure. The belief is that this procedure induces load history effects which cause remote closure from plasticity and/or roughness changes in the surface morphology. However, experimental studies performed by the authors have shown that the increase in crack closure is a result of extensive crack tip bifurcations that can occur in some materials, particularly in aluminum alloys, when the crack tip cyclic yield zone size becomes less than the grain size of the alloy. This behavior is related to the high stacking fault energy (SFE) property of aluminum alloys which results in easier slip characteristics. Therefore, the fanning behavior which occurs in aluminum alloys is a function of intrinsic dislocation property of the alloy, and therefore, the fanned data does represent the true threshold properties of the material. However, for the corrosion sensitive steel alloys tested in laboratory air, the occurrence of fanning results from fretting corrosion at the crack tips, and these results should not be considered to be representative of valid threshold properties because the fanning is

  16. The Reduction of Vertical Interchannel Crosstalk: The Analysis of Localisation Thresholds for Natural Sound Sources

    Directory of Open Access Journals (Sweden)

    Rory Wallis


    Full Text Available In subjective listening tests, natural sound sources were presented to subjects as vertically-oriented phantom images from two layers of loudspeakers, ‘height’ and ‘main’. Subjects were required to reduce the amplitude of the height layer until the position of the resultant sound source matched that of the same source presented from the main layer only (the localisation threshold. Delays of 0, 1 and 10 ms were applied to the height layer with respect to the main, with vertical stereophonic and quadraphonic conditions being tested. The results of the study showed that the localisation thresholds obtained were not significantly affected by sound source or presentation method. Instead, the only variable whose effect was significant was interchannel time difference (ICTD. For ICTD of 0 ms, the median threshold was −9.5 dB, which was significantly lower than the −7 dB found for both 1 and 10 ms. The results of the study have implications both for the recording of sound sources for three-dimensional (3D audio reproduction formats and also for the rendering of 3D images.

  17. Steplike intensity threshold behavior of extreme ionization in laser-driven xenon clusters. (United States)

    Döppner, T; Müller, J P; Przystawik, A; Göde, S; Tiggesbäumker, J; Meiwes-Broer, K-H; Varin, C; Ramunno, L; Brabec, T; Fennel, T


    The generation of highly charged Xe(q+) ions up to q=24 is observed in Xe clusters embedded in helium nanodroplets and exposed to intense femtosecond laser pulses (λ=800  nm). Laser intensity resolved measurements show that the high-q ion generation starts at an unexpectedly low threshold intensity of about 10(14)  W/cm2. Above threshold, the Xe ion charge spectrum saturates quickly and changes only weakly for higher laser intensities. Good agreement between these observations and a molecular dynamics analysis allows us to identify the mechanisms responsible for the highly charged ion production and the surprising intensity threshold behavior of the ionization process.

  18. Kids are not little adults: what MET threshold captures sedentary behavior in children? (United States)

    Saint-Maurice, Pedro F; Kim, Youngwon; Welk, Gregory J; Gaesser, Glenn A


    The study compares MET-defined cutpoints used to classify sedentary behaviors in children using a simulated free-living design. A sample of 102 children (54 boys and 48 girls; 7-13 years) completed a set of 12 activities (randomly selected from a pool of 24 activities) in a random order. Activities were predetermined and ranged from sedentary to vigorous intensities. Participant's energy expenditure was measured using a portable indirect calorimetry system, Oxycon mobile. Measured minute-by-minute VO2 values (i.e., ml/kg/min) were converted to an adult- or child-MET value using the standard 3.5 ml/kg/min or the estimated child resting metabolic rate, respectively. Classification agreement was examined for both the "standard" (1.5 adult-METs) and an "adjusted" (2.0 adult-METs) MET-derived threshold for classifying sedentary behavior. Alternatively, we also tested the classification accuracy of a 1.5 child-MET threshold. Classification accuracy of sedentary activities was evaluated relative to the predetermined intensity categorization using receiver operator characteristic curves. There were clear improvements in the classification accuracy for sedentary activities when a threshold of 2.0 adult-METs was used instead of 1.5 METs (Se1.5 METs = 4.7%, Sp1.5 METs = 100.0%; Se2.0 METs = 36.9%, Sp2.0 METs = 100.0 %). The use of child-METs while maintaining the 1.5 threshold also resulted in improvements in classification (Se = 45.1%, Sp = 100.0%). Adult-MET thresholds are not appropriate for children when classifying sedentary activities. Classification accuracy for identifying sedentary activities was improved when either an adult-MET of 2.0 or a child-MET of 1.5 was used.

  19. Quantifying utricular stimulation during natural behavior (United States)

    Rivera, Angela R. V.; Davis, Julian; Grant, Wally; Blob, Richard W.; Peterson, Ellengene; Neiman, Alexander B.; Rowe, Michael


    The use of natural stimuli in neurophysiological studies has led to significant insights into the encoding strategies used by sensory neurons. To investigate these encoding strategies in vestibular receptors and neurons, we have developed a method for calculating the stimuli delivered to a vestibular organ, the utricle, during natural (unrestrained) behaviors, using the turtle as our experimental preparation. High-speed digital video sequences are used to calculate the dynamic gravito-inertial (GI) vector acting on the head during behavior. X-ray computed tomography (CT) scans are used to determine the orientation of the otoconial layer (OL) of the utricle within the head, and the calculated GI vectors are then rotated into the plane of the OL. Thus, the method allows us to quantify the spatio-temporal structure of stimuli to the OL during natural behaviors. In the future, these waveforms can be used as stimuli in neurophysiological experiments to understand how natural signals are encoded by vestibular receptors and neurons. We provide one example of the method which shows that turtle feeding behaviors can stimulate the utricle at frequencies higher than those typically used in vestibular studies. This method can be adapted to other species, to other vestibular end organs, and to other methods of quantifying head movements. PMID:22753360

  20. Threshold behavior in single-photon double ionization of atomic oxygen (United States)

    He, Z. X.; Moberg, R.; Samson, J. A. R.


    The threshold behavior of the single-photon double-ionization cross section of atomic oxygen has been studied using vacuum uv radiation from a synchrotron storage ring. The double-ionization cross section appears to follow a power law Eα (where E is the kinetic energy of the two electrons) from its threshold to about 2.0 eV above with an exponent α=1.08+/-0.03, which is consistent with Wannier's theoretical value of 1.056. The cross section also shows the influence of the doubly excited 2s2p3nln'l' (n,n'>~3) neutral states, among which the first three converge to the 2s2p3(5So)4p(6Po) ionic state of oxygen.

  1. Foster placement disruptions associated with problem behavior: mitigating a threshold effect. (United States)

    Fisher, Philip A; Stoolmiller, Mike; Mannering, Anne M; Takahashi, Aiko; Chamberlain, Patricia


    Placement disruptions have adverse effects on foster children. Identifying reliable predictors of placement disruptions might assist in the allocation of services to prevent disruptions. There were two objectives in this study: (a) to replicate a prior finding that the number of daily child problem behaviors at entry into a new foster home predicts subsequent placement disruptions in foster preschoolers and (b) to determine whether this association is mitigated by a treatment foster care intervention. Problem behavior and placement disruptions were examined in 60 children in regular foster care (age range = 3.10-5.91 years [M = 4.34, SD = 0.83], 58.3% male, 93.4% Caucasian) and 57 children in a treatment foster care program (age range = 3.01-6.78 years [M = 4.54, SD = 0.86], 49.1% male, 82.5% Caucasian). Using the Parent Daily Report Checklist (Chamberlain & Reid, 1987), a brief telephone interview, foster caregivers reported problem behavior 6 times over 3 months. Placement disruptions were tracked over 12 months. The regular foster care children with 5 or fewer problem behaviors were at low risk for disruption, but their risk increased 10% for each additional behavior (p = .013). The intervention appeared to mitigate this "threshold effect"; number of problem behaviors did not predict risk of placement disruption in the treatment foster care group (p = .63). These findings replicate previous evidence linking child problem behavior to placement disruptions and further highlight the need for early preventative interventions.

  2. A system dynamics model of clinical decision thresholds for the detection of developmental-behavioral disorders

    Directory of Open Access Journals (Sweden)

    R. Christopher Sheldrick


    Full Text Available Abstract Background Clinical decision-making has been conceptualized as a sequence of two separate processes: assessment of patients’ functioning and application of a decision threshold to determine whether the evidence is sufficient to justify a given decision. A range of factors, including use of evidence-based screening instruments, has the potential to influence either or both processes. However, implementation studies seldom specify or assess the mechanism by which screening is hypothesized to influence clinical decision-making, thus limiting their ability to address unexpected findings regarding clinicians’ behavior. Building on prior theory and empirical evidence, we created a system dynamics (SD model of how physicians’ clinical decisions are influenced by their assessments of patients and by factors that may influence decision thresholds, such as knowledge of past patient outcomes. Using developmental-behavioral disorders as a case example, we then explore how referral decisions may be influenced by changes in context. Specifically, we compare predictions from the SD model to published implementation trials of evidence-based screening to understand physicians’ management of positive screening results and changes in referral rates. We also conduct virtual experiments regarding the influence of a variety of interventions that may influence physicians’ thresholds, including improved access to co-located mental health care and improved feedback systems regarding patient outcomes. Results Results of the SD model were consistent with recent implementation trials. For example, the SD model suggests that if screening improves physicians’ accuracy of assessment without also influencing decision thresholds, then a significant proportion of children with positive screens will not be referred and the effect of screening implementation on referral rates will be modest—results that are consistent with a large proportion of published

  3. The threshold hypothesis: solving the equation of nurture vs nature in type 1 diabetes. (United States)

    Wasserfall, C; Nead, K; Mathews, C; Atkinson, M A


    For more than 40 years, the contributions of nurture (i.e. the environment) and nature (i.e. genetics) have been touted for their aetiological importance in type 1 diabetes. Disappointingly, knowledge gains in these areas, while individually successful, have to a large extent occurred in isolation from each other. One reason underlying this divide is the lack of a testable model that simultaneously considers the contributions of genetic and environmental determinants in the formation of this and potentially other disorders that are subject to these variables. To address this void, we have designed a model based on the hypothesis that the aetiological influences of genetics and environment, when evaluated as intersecting and reciprocal trend lines based on odds ratios, result in a method of concurrently evaluating both facets and defining the attributable risk of clinical onset of type 1 diabetes. The model, which we have elected to term the 'threshold hypothesis', also provides a novel means of conceptualising the complex interactions of nurture with nature in type 1 diabetes across various geographical populations.

  4. Effects of airgun sounds on bowhead whale calling rates: evidence for two behavioral thresholds.

    Directory of Open Access Journals (Sweden)

    Susanna B Blackwell

    Full Text Available In proximity to seismic operations, bowhead whales (Balaena mysticetus decrease their calling rates. Here, we investigate the transition from normal calling behavior to decreased calling and identify two threshold levels of received sound from airgun pulses at which calling behavior changes. Data were collected in August-October 2007-2010, during the westward autumn migration in the Alaskan Beaufort Sea. Up to 40 directional acoustic recorders (DASARs were deployed at five sites offshore of the Alaskan North Slope. Using triangulation, whale calls localized within 2 km of each DASAR were identified and tallied every 10 minutes each season, so that the detected call rate could be interpreted as the actual call production rate. Moreover, airgun pulses were identified on each DASAR, analyzed, and a cumulative sound exposure level was computed for each 10-min period each season (CSEL10-min. A Poisson regression model was used to examine the relationship between the received CSEL10-min from airguns and the number of detected bowhead calls. Calling rates increased as soon as airgun pulses were detectable, compared to calling rates in the absence of airgun pulses. After the initial increase, calling rates leveled off at a received CSEL10-min of ~94 dB re 1 μPa2-s (the lower threshold. In contrast, once CSEL10-min exceeded ~127 dB re 1 μPa2-s (the upper threshold, whale calling rates began decreasing, and when CSEL10-min values were above ~160 dB re 1 μPa2-s, the whales were virtually silent.

  5. Threshold behaviors of social dynamics and financial outcomes of Ponzi scheme diffusion in complex networks (United States)

    Fu, Peihua; Zhu, Anding; Ni, He; Zhao, Xin; Li, Xiulin


    Ponzi schemes always lead to mass disasters after collapse. It is important to study the critical behaviors of both social dynamics and financial outcomes for Ponzi scheme diffusion in complex networks. We develop the potential-investor-divestor-investor (PIDI) model by considering the individual behavior of direct reinvestment. We find that only the spreading rate relates to the epidemic outbreak while the reinvestment rate relates to the zero and non-zero final states for social dynamics of both homo- and inhomogeneous networks. Financially, we find that there is a critical spreading threshold, above which the scheme needs not to use its own initial capital for taking off, i.e. the starting cost is covered by the rapidly inflowing funds. However, the higher the cost per recruit, the larger the critical spreading threshold and the worse the financial outcomes. Theoretical and simulation results also reveal that schemes are easier to take off in inhomogeneous networks. The reinvestment rate does not affect the starting. However, it improves the financial outcome in the early stages and postpones the outbreak of financial collapse. Some policy suggestions for the regulator from the perspective of social physics are proposed in the end of the paper.

  6. Megascale processes: Natural disasters and human behavior (United States)

    Kieffer, S.W.; Barton, P.; Chesworth, W.; Palmer, A.R.; Reitan, P.; Zen, E.-A.


    Megascale geologic processes, such as earthquakes, tsunamis, volcanic eruptions, floods, and meteoritic impacts have occurred intermittently throughout geologic time, and perhaps on several planets. Unlike other catastrophes discussed in this volume, a unique process is unfolding on Earth, one in which humans may be the driving agent of megadisasters. Although local effects on population clusters may have been catastrophic in the past, human societies have never been interconnected globally at the scale that currently exists. We review some megascale processes and their effects in the past, and compare present conditions and possible outcomes. We then propose that human behavior itself is having effects on the planet that are comparable to, or greater than, these natural disasters. Yet, unlike geologic processes, human behavior is potentially under our control. Because the effects of our behavior threaten the stability, or perhaps even existence, of a civilized society, we call for the creation of a body to institute coherent global, credible, scientifi cally based action that is sensitive to political, economic, religious, and cultural values. The goal would be to institute aggressive monitoring, identify and understand trends, predict their consequences, and suggest and evaluate alternative actions to attempt to rescue ourselves and our ecosystems from catastrophe. We provide a template modeled after several existing national and international bodies. ?? 2009 The Geological Society of America.

  7. Effect of infrared radiation on the threshold behavior of scattering (and decay) processes

    International Nuclear Information System (INIS)

    Mohanty, A.K.; Rosenberg, L.; Spruch, L.


    An analysis is given of the effect of radiative corrections on the threshold behavior of the cross section for the inelastic scattering of a light charged particle by a neutral composite system. Explicit results are obtained for a model problem where the target consists of a proton and antiproton bound under their mutual Coulomb interaction and excited to a 2p state from its 1s ground state by electron impact, but the conclusions drawn are applicable, qualitatively, to a wide range of problems. It is found that when the energy resolution Δepsilon-c of the electron detector is small compared with the kinetic energy K' of the electron in the final state, the more careful treatment given here, which properly accounts for the rapid variation of the cross section for scattering energies near threshold, leads to only small modifications in the standard form of the radiative correction factor δ. For sufficiently high resolution in energy of a (high-energy) incident beam, the modification could be significant if Δepsilon-c is comparable with K'. The above considerations are applicable not only to scattering cross sections but to endpoints of the energy spectrum of the charged particle in a decay process in which only one charged particle is emitted

  8. Variations of Geomagnetic Cosmic Ray Thresholds and Their Latitudinal Behavior in the Period of Solar Disturbance in September 2005 (United States)

    Tyasto, M. I.; Danilova, O. A.; Sdobnov, V. E.


    The period of interplanetary, geomagnetic and solar disturbances of September 7-15, 2005, is characterized by two sharp increases of solar wind velocity to 1000 km/s and great Dst variation of the geomagnetic field ( 140 nT). The time variations of theoretical and experimental geomagnetic thresholds observed during this strong geomagnetic storm, their connection with solar wind parameters and the Dst index, and the features of latitudinal behavior of geomagnetic thresholds at particular times of the storm were studied. The theoretical geomagnetic thresholds were calculated with cosmic ray particle tracing in the magnetic field of the disturbed magnetosphere described by Ts01 model. The experimental geomagnetic thresholds were specified by spectrographic global survey according to the data of cosmic ray registration by the global station network.

  9. Relationship Between Unusual High-Temperature Fatigue Crack Growth Threshold Behavior in Superalloys and Sudden Failure Mode Transitions (United States)

    Telesman, J.; Smith, T. M.; Gabb, T. P.; Ring, A. J.


    An investigation of high temperature cyclic fatigue crack growth (FCG) threshold behavior of two advanced nickel disk alloys was conducted. The focus of the study was the unusual crossover effect in the near-threshold region of these type of alloys where conditions which produce higher crack growth rates in the Paris regime, produce higher resistance to crack growth in the near threshold regime. It was shown that this crossover effect is associated with a sudden change in the fatigue failure mode from a predominant transgranular mode in the Paris regime to fully intergranular mode in the threshold fatigue crack growth region. This type of a sudden change in the fracture mechanisms has not been previously reported and is surprising considering that intergranular failure is typically associated with faster crack growth rates and not the slow FCG rates of the near-threshold regime. By characterizing this behavior as a function of test temperature, environment and cyclic frequency, it was determined that both the crossover effect and the onset of intergranular failure are caused by environmentally driven mechanisms which have not as yet been fully identified. A plausible explanation for the observed behavior is proposed.

  10. Natural course of behavioral addictions: a 5-year longitudinal study


    Konkol? Thege, Barna; Woodin, Erica M; Hodgins, David C; Williams, Robert J


    Background Resolving the theoretical controversy on the labeling of an increasing number of excessive behaviors as behavioral addictions may also be facilitated by more empirical data on these behavioral problems. For instance, an essential issue to the classification of psychiatric disorders is information on their natural course. However, longitudinal research on the chronic vs. episodic nature of behavioral addictions is scarce. The aim of the present study, therefore, was to provide data ...

  11. Biological Principles and Threshold Concepts for Understanding Natural Selection. Implications for Developing Visualizations as a Pedagogic Tool (United States)

    Tibell, Lena A. E.; Harms, Ute


    Modern evolutionary theory is both a central theory and an integrative framework of the life sciences. This is reflected in the common references to evolution in modern science education curricula and contexts. In fact, evolution is a core idea that is supposed to support biology learning by facilitating the organization of relevant knowledge. In addition, evolution can function as a pivotal link between concepts and highlight similarities in the complexity of biological concepts. However, empirical studies in many countries have for decades identified deficiencies in students' scientific understanding of evolution mainly focusing on natural selection. Clearly, there are major obstacles to learning natural selection, and we argue that to overcome them, it is essential to address explicitly the general abstract concepts that underlie the biological processes, e.g., randomness or probability. Hence, we propose a two-dimensional framework for analyzing and structuring teaching of natural selection. The first—purely biological—dimension embraces the three main principles variation, heredity, and selection structured in nine key concepts that form the core idea of natural selection. The second dimension encompasses four so-called thresholds, i.e., general abstract and/or non-perceptual concepts: randomness, probability, spatial scales, and temporal scales. We claim that both of these dimensions must be continuously considered, in tandem, when teaching evolution in order to allow development of a meaningful understanding of the process. Further, we suggest that making the thresholds tangible with the aid of appropriate kinds of visualizations will facilitate grasping of the threshold concepts, and thus, help learners to overcome the difficulties in understanding the central theory of life.

  12. Evidence for thermally assisted threshold switching behavior in nanoscale phase-change memory cells

    Energy Technology Data Exchange (ETDEWEB)

    Le Gallo, Manuel; Athmanathan, Aravinthan; Krebs, Daniel; Sebastian, Abu [IBM Research-Zurich, 8803 Rüschlikon (Switzerland)


    In spite of decades of research, the details of electrical transport in phase-change materials are still debated. In particular, the so-called threshold switching phenomenon that allows the current density to increase steeply when a sufficiently high voltage is applied is still not well understood, even though there is wide consensus that threshold switching is solely of electronic origin. However, the high thermal efficiency and fast thermal dynamics associated with nanoscale phase-change memory (PCM) devices motivate us to reassess a thermally assisted threshold switching mechanism, at least in these devices. The time/temperature dependence of the threshold switching voltage and current in doped Ge{sub 2}Sb{sub 2}Te{sub 5} nanoscale PCM cells was measured over 6 decades in time at temperatures ranging from 40 °C to 160 °C. We observe a nearly constant threshold switching power across this wide range of operating conditions. We also measured the transient dynamics associated with threshold switching as a function of the applied voltage. By using a field- and temperature-dependent description of the electrical transport combined with a thermal feedback, quantitative agreement with experimental data of the threshold switching dynamics was obtained using realistic physical parameters.

  13. A brief peripheral motion contrast threshold test predicts older drivers' hazardous behaviors in simulated driving. (United States)

    Henderson, Steven; Woods-Fry, Heather; Collin, Charles A; Gagnon, Sylvain; Voloaca, Misha; Grant, John; Rosenthal, Ted; Allen, Wade


    Our research group has previously demonstrated that the peripheral motion contrast threshold (PMCT) test predicts older drivers' self-report accident risk, as well as simulated driving performance. However, the PMCT is too lengthy to be a part of a battery of tests to assess fitness to drive. Therefore, we have developed a new version of this test, which takes under two minutes to administer. We assessed the motion contrast thresholds of 24 younger drivers (19-32) and 25 older drivers (65-83) with both the PMCT-10min and the PMCT-2min test and investigated if thresholds were associated with measures of simulated driving performance. Younger participants had significantly lower motion contrast thresholds than older participants and there were no significant correlations between younger participants' thresholds and any measures of driving performance. The PMCT-10min and the PMCT-2min thresholds of older drivers' predicted simulated crash risk, as well as the minimum distance of approach to all hazards. This suggests that our tests of motion processing can help predict the risk of collision or near collision in older drivers. Thresholds were also correlated with the total lane deviation time, suggesting a deficiency in processing of peripheral flow and delayed detection of adjacent cars. The PMCT-2min is an improved version of a previously validated test, and it has the potential to help assess older drivers' fitness to drive. Copyright © 2015 Elsevier Ltd. All rights reserved.

  14. Irreversible mean-field model of the critical behavior of charge-density waves below the threshold for sliding (United States)

    Sornette, Didier


    A mean-field (MF) model of the critical behavior of charge-density waves below the threshold for sliding is proposed, which replaces the combined effect of the pinning force and of the forces exerted by the neighbors on a given particle n by an effective force threshold Xn. It allows one to rationalize the numerical results of Middleton and Fisher [Phys. Rev. Lett. 66 (1991) 92] on the divergence of the polarization and of the largest correlation length and of Pla and Nori [Phys. Rev. Lett. 67 (1991) 919] on the distribution D( d) of sliding bursts of size d, measured in narrow intervals of driving fields E at a finite distance below the threshold Ec.

  15. Assessing the importance of natural behavior for animal welfare

    NARCIS (Netherlands)

    Bracke, M.B.M.; Hopster, H.


    The concept of natural behavior is a key element in current Dutch policy-making on animal welfare. It emphasizes that animals need positive experiences, in addition to minimized suffering. This paper interprets the concept of natural behavior in the context of the scientific framework for welfare

  16. Accelerated Near-Threshold Fatigue Crack Growth Behavior of an Aluminum Powder Metallurgy Alloy (United States)

    Piascik, Robert S.; Newman, John A.


    Fatigue crack growth (FCG) research conducted in the near threshold regime has identified a room temperature creep crack growth damage mechanism for a fine grain powder metallurgy (PM) aluminum alloy (8009). At very low DK, an abrupt acceleration in room temperature FCG rate occurs at high stress ratio (R = Kmin/Kmax). The near threshold accelerated FCG rates are exacerbated by increased levels of Kmax (Kmax less than 0.4 KIC). Detailed fractographic analysis correlates accelerated FCG with the formation of crack-tip process zone micro-void damage. Experimental results show that the near threshold and Kmax influenced accelerated crack growth is time and temperature dependent.

  17. Pattern segmentation with activity dependent natural frequency shift and sub-threshold resonance. (United States)

    Shtrahman, E; Zochowski, M


    Understanding the mechanisms underlying distributed pattern formation in brain networks and its content driven dynamical segmentation is an area of intense study. We investigate a theoretical mechanism for selective activation of diverse neural populations that is based on dynamically shifting cellular resonances in functionally or structurally coupled networks. We specifically show that sub-threshold neuronal depolarization from synaptic coupling or external input can shift neurons into and out of resonance with specific bands of existing extracellular oscillations, and this can act as a dynamic readout mechanism during information storage and retrieval. We find that this mechanism is robust and suggest it as a general coding strategy that can be applied to any network with oscillatory nodes.

  18. Assessing the Electrode-Neuron Interface with the Electrically Evoked Compound Action Potential, Electrode Position, and Behavioral Thresholds. (United States)

    DeVries, Lindsay; Scheperle, Rachel; Bierer, Julie Arenberg


    Variability in speech perception scores among cochlear implant listeners may largely reflect the variable efficacy of implant electrodes to convey stimulus information to the auditory nerve. In the present study, three metrics were applied to assess the quality of the electrode-neuron interface of individual cochlear implant channels: the electrically evoked compound action potential (ECAP), the estimation of electrode position using computerized tomography (CT), and behavioral thresholds using focused stimulation. The primary motivation of this approach is to evaluate the ECAP as a site-specific measure of the electrode-neuron interface in the context of two peripheral factors that likely contribute to degraded perception: large electrode-to-modiolus distance and reduced neural density. Ten unilaterally implanted adults with Advanced Bionics HiRes90k devices participated. ECAPs were elicited with monopolar stimulation within a forward-masking paradigm to construct channel interaction functions (CIF), behavioral thresholds were obtained with quadrupolar (sQP) stimulation, and data from imaging provided estimates of electrode-to-modiolus distance and scalar location (scala tympani (ST), intermediate, or scala vestibuli (SV)) for each electrode. The width of the ECAP CIF was positively correlated with electrode-to-modiolus distance; both of these measures were also influenced by scalar position. The ECAP peak amplitude was negatively correlated with behavioral thresholds. Moreover, subjects with low behavioral thresholds and large ECAP amplitudes, averaged across electrodes, tended to have higher speech perception scores. These results suggest a potential clinical role for the ECAP in the objective assessment of individual cochlear implant channels, with the potential to improve speech perception outcomes.

  19. Political behavior in organizational context: nature, research and paradigm

    Directory of Open Access Journals (Sweden)

    Hasan Jafariani


    Full Text Available This paper investigates political behavior in organization context. In the first section, it studies inappropriate terminology in political behavior arena and recommends that political behaviors are neither positive nor negative in nature. The study also demonstrates that ends and means for influencing others are two criteria for determining faces of political behavior. In the second section, related and important research are reviewed and categorized in terms of content. Finally, we present the dominant paradigm of political behavior as a philosophical infrastructure. The study also presents some guidelines for further research the limitations are discussed in conclusion part.

  20. Cell size dependent toxicity thresholds of polycyclic aromatic hydrocarbons to natural and cultured phytoplankton populations

    Energy Technology Data Exchange (ETDEWEB)

    Echeveste, Pedro, E-mail: pedro.echeveste@uib.e [Department of Global Change Research, IMEDEA (CSIC-UIB) Instituto Mediterraneo de Estudios Avanzados, Miquel Marques 21, 07190 Esporles (Spain); Agusti, Susana, E-mail: sagusti@uib.e [Department of Global Change Research, IMEDEA (CSIC-UIB) Instituto Mediterraneo de Estudios Avanzados, Miquel Marques 21, 07190 Esporles (Spain); Dachs, Jordi, E-mail: jdmqam@cid.csic.e [Department of Environmental Chemistry, Institute of Environmental Assessment and Water Studies (IDAEA-CSIC), Jordi Girona Salgado 18, 08034 Barcelona (Spain)


    The toxicity of pyrene and phenanthrene to phytoplankton was studied by analyzing the effect on the growth, abundance and cell viability of cultured species and natural communities of the Atlantic Ocean and the Mediterranean Sea. A decrease in cell abundance, and growth rate was observed as concentration of PAHs increased, with catastrophic cell mortality induced at the highest PAH concentration tested. A strong positive linear relationship was observed between the LC50 (the PAH concentration at which cell population will decline by a half), and the species cell volume, for both phenanthrene and pyrene. Natural communities were however significantly more sensitive to PAHs than cultured phytoplankton, as indicated by the lower slope (e.g. 0.23 and 0.65, respectively, for pyrene) of the relationship LC50 vs. cell volume. The results highlight the importance of cell size in determining the phytoplankton sensitivity to PAHs identifying the communities from the oligotrophic ocean to be more vulnerable. - Cell size is the major factor determining phytoplankton sensitivity to PAHs.

  1. Dynamic Choice Behavior in a Natural Experiment

    DEFF Research Database (Denmark)

    Andersen, Steffen; Harrison, Glenn W.; Lau, Morten

    evidence of some probability weighting, but no loss aversion. We also find evidence that contestants make decisions as if using more than one latent criteria, mixing traditional utility evaluations, probability weighting, and aspiration levels. Fourth, we design and implement laboratory experiments...... linked to current choices. We have four major findings. First, we show that popular utility functions that assume constant relative or absolute risk aversion and expected utility theory defined over the prizes cannot characterize these choices, which exhibit increasing relative risk aversion over prizes...... the income that they bring to the game show. Allowing for this integration of income and game show prizes leads to choice behavior consistent with constant relative risk aversion. Third, we examine th e effects of allowing contestants to make choices characterized by non-standard decision models. We find...

  2. The behavior analytic perspective: its nature, prospects, and limitations for behavior therapy. (United States)

    Hawkins, R P; Forsyth, J P


    Behavior analysis is defined as a natural science approach to behavior--with both basic and applied branches--and contrasted with cognitive psychology. Behavior analysis is described as an integrated science that views a person's interactions with the environment as selecting certain behaviors--or rather, environment-behavior relations--making them more probable, given certain subsequent stimulus situations. It seeks an understanding that promotes effective action, which fits the clinical interests of behavior therapy. It promotes persistent searching for environmental causes, which has resulted in a remarkable range of successes, clinical and other. We explore the reasons that all behavior therapists are not behavior analysts and suggest needed future developments.

  3. Distributions of extreme bursts above thresholds in a fractional Lévy toy model of natural complexity. (United States)

    Watkins, Nicholas; Chapman, Sandra; Rosenberg, Sam; Credgington, Dan; Sanchez, Raul


    In 2 far-sighted contributions in the 1960s Mandelbrot showed the ubiquity of both non-Gaussian fluctuations and long-ranged temporal memory (the "Noah" and "Joseph" effects, respectively) in the natural and man-made worlds. Much subsequent work in complexity science has contributed to the physical underpinning of these effects, particularly in cases where complex interactions in a system cause a driven or random perturbation to be nonlinearly amplified in amplitude and/or spread out over a wide range of frequencies. In addition the modelling of catastrophes has begun to incorporate the insights which these approaches have offered into the likelihood of extreme and long-lived fluctuations. I will briefly survey how the application of the above ideas in the earth system has been a key focus and motivation of research into natural complexity at BAS [e.g. Watkins & Freeman, Science, 2008; Edwards et al, Nature, 2007]. I will then discuss in detail a standard toy model (linear fractional stable motion, LFSM) which combines the Noah and Joseph effects in a controllable way and explain how it differs from the widely used continuous time random walk. I will describe how LFSM is being used to explore the interplay of the above two effects in the distribution of bursts above thresholds. I will describe ongoing work to improve the accuracy of maximum likelihood-based estimation of burst size and waiting time distributions for LFSM first reported in [Watkins et al, PRE, 2009]; and will also touch on similar work for multifractal models [Watkins et al, PRL comment, 2009].

  4. Natural course of behavioral addictions: a 5-year longitudinal study. (United States)

    Konkolÿ Thege, Barna; Woodin, Erica M; Hodgins, David C; Williams, Robert J


    Resolving the theoretical controversy on the labeling of an increasing number of excessive behaviors as behavioral addictions may also be facilitated by more empirical data on these behavioral problems. For instance, an essential issue to the classification of psychiatric disorders is information on their natural course. However, longitudinal research on the chronic vs. episodic nature of behavioral addictions is scarce. The aim of the present study, therefore, was to provide data on prevalence, substance use comorbidity, and five-year trajectories of six excessive behaviors-namely exercising, sexual behavior, shopping, online chatting, video gaming, and eating. Analyses were based on the data of the Quinte Longitudinal Study, where a cohort of 4,121 adults from Ontario, Canada was followed for 5 years (2006 to 2011). The response rate was 21.3%, while retention rate was 93.9%. To assess the occurrence of each problem behavior, a single self-diagnostic question asked people whether their over-involvement in the behavior had caused significant problems for them in the past 12 months. To assess the severity of each problem behavior reported, the Behavioral Addiction Measure was administered. A mixed design ANOVA was used to investigate symptom trajectories over time for each problem behavior and whether these symptom trajectories varied as a function of sex. The large majority of people reported having problematic over-involvement for just one of these behaviors and just in a single time period. A main effect of time was found for each problem behavior, indicating a moderately strong decrease in symptom severity across time. The time x sex interaction was insignificant in each model indicating that the decreasing trend is similar for males and females. The data also showed that help seeking was very low in the case of excessive sexual behavior, shopping, online chatting, and video gaming but substantially more prevalent in the case of excessive eating and

  5. Measuring behavioral responses of sea turtles, saltwater crocodiles, and crested terns to drone disturbance to define ethical operating thresholds. (United States)

    Bevan, Elizabeth; Whiting, Scott; Tucker, Tony; Guinea, Michael; Raith, Andrew; Douglas, Ryan


    Drones are being increasingly used in innovative ways to enhance environmental research and conservation. Despite their widespread use for wildlife studies, there are few scientifically justified guidelines that provide minimum distances at which wildlife can be approached to minimize visual and auditory disturbance. These distances are essential to ensure that behavioral and survey data have no observer bias and form the basis of requirements for animal ethics and scientific permit approvals. In the present study, we documented the behaviors of three species of sea turtle (green turtles, Chelonia mydas, flatback turtles, Natator depressus, hawksbill turtles, Eretmochelys imbricata), saltwater crocodiles (Crocodylus porosus), and crested terns (Thalasseus bergii) in response to a small commercially available (1.4 kg) multirotor drone flown in Northern Territory and Western Australia. Sea turtles in nearshore waters off nesting beaches or in foraging habitats exhibited no evasive behaviors (e.g. rapid diving) in response to the drone at or above 20-30 m altitude, and at or above 10 m altitude for juvenile green and hawksbill turtles foraging on shallow, algae-covered reefs. Adult female flatback sea turtles were not deterred by drones flying forward or stationary at 10 m altitude when crawling up the beach to nest or digging a body pit or egg chamber. In contrast, flyovers elicited a range of behaviors from crocodiles, including minor, lateral head movements, fleeing, or complete submergence when a drone was present below 50 m altitude. Similarly, a colony of crested terns resting on a sand-bank displayed disturbance behaviors (e.g. flight response) when a drone was flown below 60 m altitude. The current study demonstrates a variety of behavioral disturbance thresholds for diverse species and should be considered when establishing operating conditions for drones in behavioral and conservation studies.

  6. Microstructure vs. Near-threshold Fatigue Crack Growth Behavior of an Heat-treated Ductile Iron

    Directory of Open Access Journals (Sweden)

    Radomila KONEČNÁ


    Full Text Available Perferritic isothermal ductile iron (IDI® is an intermediate grade between the low-strength grades of austempered ductile iron (ADI and pearlitic ductile iron (DI recently developed by Zanardi Fonderie Italy. IDI is produced by heat-treating an unalloyed nodular cast iron. The specific matrix microstructure is called “Perferritic” and consists predominantly of ferrite and pearlite. Compared to the pearlitic grades of nodular ductile iron, IDI combines similar strength with higher toughness as a result of the isothermal heat treatment. In this contribution the fatigue crack growth resistance and Kath of IDI are investigated and correlated to mechanical properties and microstructural features. The threshold Ka was determined using the load shedding technique as per ASTM Standard E-647 using CT specimens extracted from a cast block. Tensile specimens were extracted from the broken CT halves and used to determine the static mechanical properties. A metallographic investigation was carried out to correlate structural features and mechanical properties.DOI:

  7. Diagnostic REM sleep muscle activity thresholds in patients with idiopathic REM sleep behavior disorder with and without obstructive sleep apnea. (United States)

    McCarter, Stuart J; St Louis, Erik K; Sandness, David J; Duwell, Ethan J; Timm, Paul C; Boeve, Bradley F; Silber, Michael H


    We aimed to determine whether visual and automated rapid eye movement (REM) sleep without atonia (RSWA) methods could accurately diagnose patients with idiopathic REM sleep behavior disorder (iRBD) and comorbid obstructive sleep apnea (OSA). In iRBD patients (n = 15) and matched controls (n = 30) with and without OSA, we visually analyzed RSWA phasic burst durations, phasic, tonic, and "any" muscle activity by 3-s mini-epochs, phasic activity by 30-s (AASM rules) epochs, and automated REM atonia index (RAI). Group RSWA metrics were analyzed with regression models. Receiver operating characteristic (ROC) curves were used to determine the best diagnostic cutoff thresholds for REM sleep behavior disorder (RBD). Both split-night and full-night polysomnographic studies were analyzed. All mean RSWA phasic burst durations and muscle activities were higher in iRBD patients than in controls (p sleep behavior disorder (PD-RBD), consistent with a common mechanism and presumed underlying etiology of synucleinopathy in both groups. Copyright © 2016 Elsevier B.V. All rights reserved.

  8. Determination of the threshold of nanoparticle behavior: Structural and electronic properties study of nano-sized copper

    International Nuclear Information System (INIS)

    Torres-Vega, Juan J.; Medrano, L.R.; Landauro, C.V.; Rojas-Tapia, J.


    In the present work we determine the threshold of the nanoparticle behavior of copper nanoparticles by studying their structural and electronic properties. The studied nanoparticles contain from 13 to 8217 atoms and were obtained by molecular dynamics simulations using the Johnson potential for copper based on the embedded atom method. The results indicate that for small copper nanoparticles ( 2000atoms, ∼3.5 nm), with spherical-like external shape and large percentage of fcc-like local structure, this effect is negligible and their electronic character are similar to such expected in solid copper. Finally, it has also been shown that copper nanoparticles change their electronic character, from metallic to insulating, after increasing the strength of the chemical disorder

  9. Wild Origins: The Evolving Nature of Animal Behavior (United States)

    Flores, Ifigenia

    For billions of years, evolution has been the driving force behind the incredible range of biodiversity on our planet. Wild Origins is a concept plan for an exhibition at the National Zoo that uses case studies of animal behavior to explain the theory of evolution. Behaviors evolve, just as physical forms do. Understanding natural selection can help us interpret animal behavior and vice-versa. A living collection, digital media, interactives, fossils, and photographs will relay stories of social behavior, sex, navigation and migration, foraging, domestication, and relationships between different species. The informal learning opportunities visitors are offered at the zoo will create a connection with the exhibition's teaching points. Visitors will leave with an understanding and sense of wonder at the evolutionary view of life.

  10. The value of ASSR threshold-based bilateral hearing aid fitting in children with difficult or unreliable behavioral audiometry. (United States)

    Vlastarakos, Petros V; Vasileiou, Alexandra; Nikolopoulos, Thomas P


    We conducted an analysis to assess the relative contribution of auditory brainstem response (ABR) testing and auditory steady-state response (ASSR) testing in providing appropriate hearing aid fitting in hearing-impaired children with difficult or unreliable behavioral audiometry. Of 150 infants and children who had been referred to us for hearing assessment as part of a neonatal hearing screening and cochlear implantation program, we identified 5 who exhibited significant discrepancies between click-ABR and ASSR testing results and difficult or unreliable behavioral audiometry. Hearing aid fitting in pediatric cochlear implant candidates for a trial period of 3 to 6 months is a common practice in many implant programs, but monitoring the progress of the amplified infants and providing appropriate hearing aid fitting can be challenging. If we accept the premise that we can assess the linguistic progress of amplified infants with an acceptable degree of certainty, the auditory behavior that we are monitoring presupposes appropriate bilateral hearing aid fitting. This may become very challenging in young children, or even in older children with difficult or unreliable behavioral audiometry results. This challenge can be addressed by using data from both ABR and ASSR testing. Fitting attempts that employ data from only ABR testing provide amplification that involves the range of spoken language but is not frequency-specific. Hearing aid fitting should also incorporate and take into account ASSR data because reliance on ABR testing alone might compromise the validity of the monitoring process. In conclusion, we believe that ASSR threshold-based bilateral hearing aid fitting is necessary to provide frequency-specific amplification of hearing and appropriate propulsion in the prelinguistic vocalizations of monitored infants.

  11. Release behavior of drugs from various natural gums and polymers. (United States)

    Singh, Anupama; Sharma, Pramod Kumar; Malviya, Rishabha


    Polymers are the high molecular weight compounds of natural or synthetic origin, widely used in drug delivery of formulations. These polymers are further classified as hydrophilic or hydrophobic in nature. Depending upon this characteristic, polymers exhibit different release behavior in different media. This property plays an important role in the selection of polymers for controlled, sustained or immediate release formulations. The review highlights the literatures related to the research made on several polymers regarding the release kinetics which made them a novel approach for modifying the action of the particular formulation.

  12. Mimicry and propagation of prosocial behavior in a natural setting. (United States)

    Fischer-Lokou, Jacques; Martin, Angélique; Guéguen, Nicolas; Lamy, Lubomir


    This study tested, in a natural setting, the effect of mimicry on people's disposition toward helping others and the extent to which this helping behavior is extended to people not directly involved in the mimicry situation. In the main street of a busy town, men (n = 101) and women (n = 109) passersby were encountered and asked for directions. These passersby were subjected to mimicry by naïve confederates who mimicked either verbal behavior alone or verbal and nonverbal behaviors together, including arm, hand, and head movements. In the control condition, passersby were not mimicked. Following this first encounter, each subject was then met further down the street by a second confederate who asked for money. The results show that people who had been mimicked complied more often with a request for money and gave significantly more, suggesting they were more helpful and more generous toward other people, even complete strangers.

  13. Time series analysis of the behavior of brazilian natural rubber

    Directory of Open Access Journals (Sweden)

    Antônio Donizette de Oliveira


    Full Text Available The natural rubber is a non-wood product obtained of the coagulation of some lattices of forest species, being Hevea brasiliensis the main one. Native from the Amazon Region, this species was already known by the Indians before the discovery of America. The natural rubber became a product globally valued due to its multiple applications in the economy, being its almost perfect substitute the synthetic rubber derived from the petroleum. Similarly to what happens with other countless products the forecast of future prices of the natural rubber has been object of many studies. The use of models of forecast of univariate timeseries stands out as the more accurate and useful to reduce the uncertainty in the economic decision making process. This studyanalyzed the historical series of prices of the Brazilian natural rubber (R$/kg, in the Jan/99 - Jun/2006 period, in order tocharacterize the rubber price behavior in the domestic market; estimated a model for the time series of monthly natural rubberprices; and foresaw the domestic prices of the natural rubber, in the Jul/2006 - Jun/2007 period, based on the estimated models.The studied models were the ones belonging to the ARIMA family. The main results were: the domestic market of the natural rubberis expanding due to the growth of the world economy; among the adjusted models, the ARIMA (1,1,1 model provided the bestadjustment of the time series of prices of the natural rubber (R$/kg; the prognosis accomplished for the series supplied statistically adequate fittings.

  14. Behavior of natural radionuclides in wastewater treatment plants

    International Nuclear Information System (INIS)

    Camacho, A.; Montaña, M.; Vallés, I.; Devesa, R.; Céspedes-Sánchez, R.; Serrano, I.; Blázquez, S.; Barjola, V.


    56 samples, including influent, primary effluent, secondary effluent and final effluent wastewater from two Spanish municipal wastewater treatment plants (WWTPs), were analyzed to assess both the occurrence and behavior of natural radioactivity during 12 sampling campaigns carried out over the period 2007–2010. Influent and final effluent wastewaters were sampled by taking into account the hydraulic residence time within the WWTP. A wide range of gross alpha activities (15–129 mBq/L) and gross beta activities (477–983 mBq/L) in liquid samples were obtained. A correlation analysis between radioactivity in liquid samples and the performance characteristics of the WWTPs was performed. The results in liquid samples showed that gross beta activities were not influenced by treatment in the studied WWTPs. However, gross alpha activities behave differently and an increase was detected in the effluent values compared with influent wastewater. This behavior was due to the increase in the total dissolved uranium produced during secondary treatment. The results indicate that the radiological characteristics of the effluents do not present a significant radiological risk and make them suitable for future applications. - Highlights: ► Liquids from WWTPs were analyzed to know the behavior of natural radionuclides. ► Gross beta activities were not influenced by treatment in the studied WWTPs. ► Increase in gross alpha activity was observed due to uranium desorption/solubilisation. ► Correlation between gross alpha activity and the chemical oxygen demand was found

  15. Rheological behavior of raw natural rubber coagulated by microorganisms

    Directory of Open Access Journals (Sweden)

    Zhifen Wang


    Full Text Available Tests of the strain sweep, frequency sweep and stress relaxation for raw natural rubber coagulated by microorganisms (NR-m and raw natural rubber coagulated by acid (NR-a were carried out with the use of a rubber process analyzer (RPA. The results showed that the storage torque, complex viscosity of NR-m were higher than those of NR-a while the loss factor was lower. The effect of temperature on viscosity of raw NR was studied following the Arrhenious-Frenkel-Eyring model. The viscous flow behavior of NR-m was poorer than those of NR-a. Furthermore, stress relaxation measurements of raw NR showed a longer period of relaxation for NR-m.

  16. Competitive behavior of photons contributing to junction voltage jump in narrow band-gap semiconductor multi-quantum-well laser diodes at lasing threshold (United States)

    Feng, Liefeng; Yang, Xiufang; Li, Yang; Li, Ding; Wang, Cunda; Yao, Dongsheng; Hu, Xiaodong; Li, Hongru


    The junction behavior of different narrow band-gap multi-quantum-well (MQW) laser diodes (LDs) confirmed that the jump in the junction voltage in the threshold region is a general characteristic of narrow band-gap LDs. The relative change in the 1310 nm LD is the most obvious. To analyze this sudden voltage change, the threshold region is divided into three stages by Ithl and Ithu, as shown in Fig. 2; Ithl is the conventional threshold, and as long as the current is higher than this threshold, lasing exists and the IdV/dI-I plot drops suddenly; Ithu is the steady lasing point, at which the separation of the quasi-Fermi levels of electron and holes across the active region (Vj) is suddenly pinned. Based on the evolutionary model of dissipative structure theory, the rate equations of the photons in a single-mode LD were deduced in detail at Ithl and Ithu. The results proved that the observed behavior of stimulated emission suddenly substituting for spontaneous emission, in a manner similar to biological evolution, must lead to a sudden increase in the injection carriers in the threshold region, which then causes the sudden increase in the junction voltage in this region.

  17. Implicit function with natural behavior over entire domain

    International Nuclear Information System (INIS)

    To generate a smooth implicit function that behaves naturally over an entire domain, a method to smoothly combine an implicit function f(x) with a global support function g(x) has been proposed. The proposed method can be applied to large scattered point data, since the implicit function f(x) is generated by a partition-of-unity-based method. The global support function g(x) is generated by a radial basis function-based method or by the least-squares method. To ensure a smooth combination of f(x) and g(x), an appropriate weight function is employed. In numerical experiments, the proposed method is applied to large point data. The results illustrate that the proposed method can generate a smooth implicit function F(x) with natural behavior over the entire domain. In addition, on the given points, the accuracy of F(x) is exactly the same as that of f(x). Furthermore, the computational cost for generation of F(x) is almost the same as that of f(x). (author)

  18. Estimating extreme environmental variables by POT methods: behavior of Maximum Likelihood Estimators and distinction between statistical threshold and location parameter (United States)

    Mazas, Franck; Hamm, Luc; Garat, Philippe


    For a decade, the methodology for determining extreme values of environmental variables has converged towards the so-called GPD-Poisson model. The Peaks-Over-Threshold (POT) method is used for extracting extreme i.i.d. data from a time series. Excesses above a statistical meaningful threshold are fit to a 2-parameter Generalized Pareto Distribution (GPD), often with the Maximum Likelihood Estimator (MLE). Last, extreme values for desired return periods (quantiles) and confidence intervals are derived. In this approach, the GPD plays the role of an asymptotic approximation of the true law of excesses; hence it is valid when the threshold is high enough: a correct determination of the threshold value is thus crucial. Besides, a close examination of the sensitivity of the estimations with respect to the threshold shows that the use of 2-parameters (scale and shape) distributions yields unstable results. Considering the GPD (results are similar with other distributions), we explain in this presentation the need for a location parameter, distinct from the threshold, and the non-optimality of ML estimators. When the threshold is allowed to vary between two consecutive data values of the extreme sample, the ML estimates of the scale and shape parameters of the distribution do not remain constant. In other words, a slight translation of the sample may lead to a significant change in the estimated quantiles, although the same physical events are extrapolated. The likelihood of the 2-parameter GPD model is continuously increasing when the threshold tends to the first value of the sample of the excesses, with non-null derivatives. When extending the model to a 3-parameter GPD (adding a location parameter), it can be shown that the maximum likelihood is reached at the open upper bound of the interval of validity of this parameter, with non-null derivatives. Still, the asymptotic properties of the MLE require that the maximum be reached on an interior point of an open set. Thus

  19. Measurement of excitation functions in proton induced reactions on natural copper from their threshold to 43 MeV

    Energy Technology Data Exchange (ETDEWEB)

    Shahid, Muhammad; Kim, Kwangsoo [Department of Physics, Kyungpook National University, Daegu 702-701 (Korea, Republic of); Naik, Haladhara [Radiochemistry Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Zaman, Muhammad [Department of Physics, Kyungpook National University, Daegu 702-701 (Korea, Republic of); Yang, Sung-Chul [Department of Physics, Kyungpook National University, Daegu 702-701 (Korea, Republic of); Nuclear Data Center, Korea Atomic Energy Research Institute, Daejeon 305-353 (Korea, Republic of); Kim, Guinyun, E-mail: [Department of Physics, Kyungpook National University, Daegu 702-701 (Korea, Republic of)


    We have measured the production cross-sections of the residual radionuclides from proton-induced reactions of {sup nat}Cu by using a stacked-foil activation and off-line γ-ray spectrometric technique in the energy range from their respective threshold to 43 MeV at the MC-50 cyclotron of the Korea Institute of Radiological and Medical Sciences. The measured results were compared with the earlier reported data as well as with the theoretical values obtained from the TENDL-2013 library based on the TALYS 1.6 code. The integral yields for thick target of the investigated radio-nuclides were calculated from the measured excitation function and the stopping power of {sup nat}Cu.

  20. Volume 1. Base technology FSAR support document: prefailure transient behavior and failure threshold. Status report, January 1975

    International Nuclear Information System (INIS)

    Baars, R.E.; Culley, G.E.; Davis, R.T.; Henderson, R.G.; Scott, J.H.


    A comprehensive compilation of the current (January 1975) state-of-the-art understanding of fuel pin response to reactivity insertion events up to and including failure threshold is presented. All mixed oxide fuel, transient overpower tests conducted to date are described and the data collected therein are presented. Current understanding of fuel pin cladding failure mechanisms is discussed, and interpretations of fuel pin cladding failure thresholds are presented as revealed by individual tests and by the several tests collectively. Plans for future tests are discussed

  1. [Distribution behaviors of phenanthrene to humic fractions in natural soil]. (United States)

    Lin, Xiu-mei; Pan, Bo; Liu, Wen-xin; Yuan, Hui-shi; Zhang, Xian-ming; Zhang, Yan-xu; Xiao, Yang; Dai, Han-cheng; Tao, Shu


    After adsorption of phenanthrene by the natural soil under different concentrations initially added, the soil sample was extracted for humic acid fraction (including humic acid and fulvic acid), and the sorption amount of phenanthrene in humin fraction was calculated to investigate the adsorption/distribution kinetics in two soil organic fractions and the corresponding influence of original phenanthrene concentration. The experimental data were fitted using Freundlich equation. The results show that, distribution of phenanthrene in the soil exhibited a multi-stage property, i.e., from a first fast sorption to a breakthrough at about 48 h, then followed by a slow sorption procedure. In the fast sorption stage (before 48 h), there was an up-to-down fluctuation of phenanthrene sorption ratio (sorption amount/added amount) in humic acid fraction, possibly due to surface sorption by minerals and competitive sorption by humin fraction. In the slow sorption stage, variations in sorption ratio in humic acid fraction was very small, and the influence of original concentration of phenanthrene was slight; while for humin fraction, the sorption ratio of phenanthrene at lower initial concentration was significantly higher than at higher one, in addition, the sorption ratio showed a gradually increasing trend, indicated humin fraction as the main domain in charge of the slow sorption. The fitting results of model parameters demonstrated that, sorption nonlinearity of phenanthrene in the natural soil increased in the following order: humic acid fractionsoilhumin fraction, and enhanced gradually. Different characteristics of humic acid and humin fractions in the multi-stage kinetics of phenanthrene sorption/distribution further reflected the effects of heterogenerity of soil organic fractions on nonlinear sorption behaviors.

  2. Hearing thresholds of harbor seals (Phoca vitulina) for playbacks of seal scarer signals, and effects of the signals on behavior

    NARCIS (Netherlands)

    Kastelein, R.A.; Helder-Hoek, L.; Gransier, R.; Terhune, J.M.; Jennings, N.; Jong, C.A.F. de


    Acoustic mitigation devices (AMDs) are used to deter marine mammals from construction sites to prevent hearing injury by offshore pile-driving noise. In order to quantify the distance at which AMDs designed as ‘seal scarers’ are detected by seals, the 50% hearing thresholds for playbacks of their

  3. Investigation of the thermal behavior of Philippine natural zeolites (United States)

    Olegario-Sanchez, Eleanor; Felizco, Jenichi Clairvaux; Mulimbayan, Francis


    This study aims to investigate the thermal behavior of natural zeolites from Mangatarem, Pangasinan, Philippines. Results obtained from the XRD pattern revealed that the sample is largely composed of mordenite, a Type I zeolite. In the chemical analysis, Si and Al are proven to be the primary components of the sample, which is typical in an aluminosilicate material. It also has a high Si/Al ratio, which suggests that the material is hydrophilic and thermally stable. The TGA analysis showed that dehydration processes dominate the sample's reaction upon heating up to 1000 °C. The initial dehydration process led to a weight loss that is almost equivalent to the moisture content, as measured by chemical analysis. The succeeding weight loss is most probably due to the dehydration of tightly-bound water and cation dehydration. No structural collapse was observed even up to 1000 °C, which suggests that the material is ideal for industrial applications. Lastly, FTIR results revealed that heating the zeolitic tuff led to possible de-alumination.

  4. Crossing the Threshold From Porn Use to Porn Problem: Frequency and Modality of Porn Use as Predictors of Sexually Coercive Behaviors. (United States)

    Marshall, Ethan A; Miller, Holly A; Bouffard, Jeff A


    According to recent statistics, as many as one in five female college students are victims of sexual assault during their college career. To combat what has been called the "Campus Rape Crisis," researchers have attempted to understand what variables are associated with sexually coercive behaviors in college males. Although investigators have found support for the relationship between pornography consumption and sexually coercive behavior, researchers typically operationalize pornography use in terms of frequency of use. Furthermore, frequency of use has been assessed vaguely and inconsistently. The current study offered a more concrete assessment of frequency of use and an additional variable not yet included for pornography use: number of modalities. Beyond examining the relationship between pornography use and sexual coercion likelihood, the current study was the first to use pornography variables in a threshold analysis to test whether there is a cut point that is predictive of sexual coercion likelihood. Analyses were conducted with a sample of 463 college males. Results indicated that both pornography use variables were significantly related to a higher likelihood of sexually coercive behaviors. When both frequency of use and number of modalities were included in the model, modalities were significant and frequency was not. In addition, significant thresholds for both pornography variables that predicted sexual coercion likelihood were identified. These results imply that factors other than frequency of use, such as number of modalities, may be more important for the prediction of sexual coercive behaviors. Furthermore, threshold analyses revealed the most significant increase in risk occurred between one modality and two, indicating that it is not pornography use in general that is related to sexual coercion likelihood, but rather, specific aspects of pornography use.

  5. Opposite change trend of electrical behavior curves near the threshold between GaAs- and GaN-multi-quantum-well laser diodes (United States)

    Feng, Liefeng; Wang, Shupeng; Li, Yang; Yang, Xiufang; Li, Ding; Wang, Cunda


    The opposite and abrupt change trends of the electrical behavior between narrow and wide bang-gap multi-quantum-well (MQW) laser diodes (LDs) in the `threshold region', which corresponds to the current region between two kinks in the Id V/d I- I curves, were confirmed from the apparent properties measured directly and junction properties extracted by our ac-IV method, as well as simulation calculations. In the threshold region, negative capacitance and series resistance curves in narrow bandgap LDs (wavelengths are 780 and 650 nm) drop down, while in wide-bandgap LDs (wavelengths are 450 and 405 nm), they jump up; the junction voltage curves in narrow bandgap LDs jump up, while in wide-bandgap LDs, they drop down. We qualitatively interpreted the opposite change trend of these electrical parameters, and concluded that different stimulated emission mechanisms caused this opposite change trend of LDs with these two types of materials.

  6. The multifactorial nature of human homosexual behavior: A brief review

    Directory of Open Access Journals (Sweden)

    Barona, Daniel


    Full Text Available Homosexual behavior has been analyzed as an evolutionary paradox in the biological context. In this review, we will try to compile the main genetic, epigenetic, hormonal, neurological and immune explanations of homosexuality, as well as the ultimate evolutionary causes of this complex behavior in the human being, incorporating information from studies in other animal species. All these factors determine the homosexual behavior, acting most of the times, simultaneously. Hereditary and non hereditary factors determine homosexual behavior, explaining its persistence despite its apparent disadvantages in relation to reproductive fitness.

  7. Hydromorphological parameters of natural channel behavior in conditions of the Hercynian System and the flysch belt of the Western Carpathians on the territory of the Czech Republic (United States)

    Kujanová, Kateřina; Matoušková, Milada; Kliment, Zdeněk


    A fundamental prerequisite for assessing the current ecological status of streams is the establishment of reference conditions for each stream type that serve as a benchmark. The hydromorphological reference conditions reflect the natural channel behavior, which is extremely variable. Significant parameters of natural channel behavior were determined using a combination of four selected statistical methods: Principal Component Analysis, Agglomerative Hierarchical Clustering, correlation, and regression. Macroscale analyses of data about altitude, stream order, channel slope, valley floor slope, sinuosity, and characteristics of the hydrological regime were conducted for 3197 reaches of major rivers in the Czech Republic with total length of 15,636 km. On the basis of selected significant parameters and their threshold values, channels were classified into groups of river characteristics based on shared behaviors. The channel behavior within these groups was validated using hydromorphological characteristics of natural channels determined during field research at reference sites. Classification of channels into groups confirmed the fundamental differences between channel behavior under conditions of the Hercynian System and the flysch belt of the Western Carpathians in the Czech Republic and determined a specific group in the flattened high areas of mountains in the Bohemian Massif. Validating confirmed the distinctions between groups of river characteristics and the uniqueness of each one; it also emphasized the benefits of using qualitative data and riparian zone characteristics for describing channel behavior. Channel slope, entrenchment ratio, bed structure, and d50 were determined as quantitative characteristics of natural channel behavior.

  8. Meteorological and Hydrogeological Warning Thresholds in the operational bulletins of the Albanian National Centre for Forecast and Monitoring of Natural Risks (United States)

    Marku, M.; Mustaqi, V.; Abazi, E.; Zaimi, K.; Vako, E.; Gjonaj, M.; Hoxhaj, F.; Deda, M.; Fiori, E.; Massabò, M.; Castelli, F.


    Most operational meteo-hydrological warning system uses fixed rainfall thresholds on given durations to switch alerting bulletins. This may be a too rough approximation in regions with strong climate gradient like Albanian, especially when this bulletins need to include the evaluation of potential ground effect like floods. In the framework of the International cooperation between the Civil Protection of Italy and Albania, the National Centre for Forecast and Monitoring of Natural Risks has been established at the Institute of Geosciences, Energy, Water and Environment (IGEWE). The Centre is supported by expertise of CIMA Research Foundation - International Centre on Environmental Monitoring. The Centre issues (every morning) on a daily basis a Meteorological Warning Bulletin (the first bulletin was issued quite recently on the 20th of December 2011). It is mostly dedicated to the precipitation forecast, the most important hazard in Albania. It covers 36 hours, starting for the noon of the current day till the end of the next day. It offers a detailed precipitation forecast for each prefecture of Albania (12 in total). The prefectures that have to do with the most problematic river (Drini) are divided in a few warning areas each homogenous with respect to climatologic and hydrologic conditions. The meteo-warning is synthetically evaluated for each prefecture; it contains the assessment of the experts about the severity of the forecasted storm in terms of average precipitations, and maximum and, possible storms (if rainfall intensity exceed 90 mm in 3 hours). Reference meteorological model is COSMO LAMI7 (managed by ARPA Bologna, Italy), its spatial resolution is 7 km and temporal resolution for the outputs is 3 hours. Also ECMWF model is available. After the pure meteorological evaluation, possible adverse ground effects are assessed with a second level of variable rainfall thresholds, whose estimated recurrence interval is compared to soil moisture dependent

  9. Filtration behavior of casein glycomacropeptide (CGMP) in an enzymatic membrane reactor: fouling control by membrane selection and threshold flux operation

    DEFF Research Database (Denmark)

    Luo, Jianquan; Morthensen, Sofie Thage; Meyer, Anne S.


    to be the most suitable membrane for this application. Low pH increased CGMP retention but produced more fouling. Higher agitation and lower CGMP concentration induced larger permeate flux and higher CGMP retention. Adsorption fouling and pore blocking by CGMP in/on membranes could be controlled by selecting...... a highly hydrophilic membrane with appropriate pore size. Operating under threshold flux could minimize the concentration polarization and cake/gel/scaling layers, but might not avoid irreversible fouling caused by adsorption and pore blocking. The effects of membrane properties, pH, agitation and CGMP...

  10. The oscillatory behavior of heated channels: an analysis of the density effect. Part I. The mechanism (non linear analysis). Part II. The oscillations thresholds (linearized analysis)

    International Nuclear Information System (INIS)

    Boure, J.


    The problem of the oscillatory behavior of heated channels is presented in terms of delay-times and a density effect model is proposed to explain the behavior. The density effect is the consequence of the physical relationship between enthalpy and density of the fluid. In the first part non-linear equations are derived from the model in a dimensionless form. A description of the mechanism of oscillations is given, based on the analysis of the equations. An inventory of the governing parameters is established. At this point of the study, some facts in agreement with the experiments can be pointed out. In the second part the start of the oscillatory behavior of heated channels is studied in terms of the density effect. The threshold equations are derived, after linearization of the equations obtained in Part I. They can be solved rigorously by numerical methods to yield: -1) a relation between the describing parameters at the onset of oscillations, and -2) the frequency of the oscillations. By comparing the results predicted by the model to the experimental behavior of actual systems, the density effect is very often shown to be the actual cause of oscillatory behaviors. (author) [fr

  11. Characterizing volumetric deformation behavior of naturally occuring bituminous sand materials

    CSIR Research Space (South Africa)

    Anochie-Boateng, Joseph


    Full Text Available indicated that the considerable amount of bitumen in the oil sands, high applied loads from mining equipment and seasonal changes in temperature are major fac- tors that control the modulus and deformation behavior of oil sands (Joseph 2002). To date... angle and cohesion are the material properties used for modeling the strength and stiffness behavior. Bulk modulus is an important material property that describes the resistance to volume change when an element of soil is subjected to hydrostat- ic...

  12. Permeation Behavior and Physical Properties of Natural Rubber Nanocomposites

    National Research Council Canada - National Science Library

    Zukas, Walter; Sennett, Michael; Welsh, Elizabeth; Rodriguez, Axel; Ziegler, David; Touchet, Paul


    .... A study was carried out to examine the effects of varying nanoparticle morphology and composition on the mechanical and barrier properties of polymer nanocomposites made with natural rubber (NR...

  13. Liberdade, lei natural e direito natural em Hobbes: limiar do direito e da política na modernidade Freedom, natural law and natural right in Hobbes: threshold of law and politics in modernity

    Directory of Open Access Journals (Sweden)

    Natalia Maruyama


    Full Text Available Liberdade e poder são dois temas que se correlacionam ao longo da história da filosofia política moderna. Nos textos de Hobbes, a ideia da liberdade como ausência de impedimentos às ações ajuda-nos a pensar o dever de obediência ao poder soberano e as relações entre política e direito. Uma situação de vácuo jurídico, em que tudo é permitido, faz-se, contudo, impossível, de modo que a solução de Hobbes consiste em sustentar a ideia do direito natural como direito originário individual vinculado à preservação da vida. Suas ideias do direito natural e da lei natural, que servem de fundamento ao dever de obediência ao soberano, amparam-se em princípios jurídicos, teológicos e biológicos. Tais princípios, entretanto, não dão conta da questão da extensão do poder soberano. Hobbes recorre à análise da linguagem. Sua teoria contratual afirma o princípio de preservação da vida na base da política e sustenta a ideia da criação e da manutenção do poder soberano no ato de linguagem implicado na estrutura representativa do pacto político.Liberty and power are two subjects correlated along the history of the political modern philosophy. In the texts of Hobbes, the idea of liberty as absence of impediments to the actions helps us to think the duty of obedience to the sovereign power and the relations between politics and right. A situation of legal vacuum, in which everything is allowed, is, nevertheless, impossible, so that the solution of Hobbes consists in supporting the idea of the natural right like original individual right linked to the preservation of the life. His ideas of the natural right and of the natural law, which serve of basis to the duty of obedience to a sovereign, lean on legal, theological and biological principles. In spite of that, such principles do not surround the question of the extension of the sovereign power. Hobbes resorts to the analysis of the language. His contractual theory affirms

  14. Modeling the Temporal Nature of Human Behavior for Demographics Prediction

    DEFF Research Database (Denmark)

    Felbo, Bjarke; Sundsøy, Pål; Pentland, Alex


    nature of the patterns in the data. From high-level assumptions we design a data representation and convolutional network architecture for modeling patterns within a week. We then examine three strategies for aggregating patterns across weeks and show that our method reaches state-of-the-art accuracy...

  15. Stealth and Natural Disasters: Science, Policy and Human Behavior (United States)

    Kieffer, S. W.


    Geophysicists, earth scientists, and other natural scientists play a key role in studying disasters, and are challenged to convey the science to the public and policy makers (including government and business). I have found it useful to introduce the concept of two general types of disasters to these audiences: natural and stealth. Natural disasters are geological phenomena over which we humans have some, but relatively little, control. Earthquakes, tsunamis, floods and volcanic eruptions are the most familiar examples, but exogenous events such as meteorite impacts, solar flares, and supernovae are also possibly disruptive. Natural disasters typically have an abrupt onset, cause immediate major change, are familiar from the historic record, and get much media and public attention. They cannot be prevented, but preplanning can ameliorate their effects. Natural disasters are increasingly amplified by us (humans), and we are increasingly affected by them due to our expanding presence on the planet. Less familiar disasters are unfolding in the near-term, but they are not happening in the minds of most people. They are approaching us stealthily, and for this reason I propose that we call them stealth disasters. They differ from natural disasters in several important ways: stealth disasters are primarily caused by, or driven by, the interaction of humans with complex cycles of processes on the planet. Examples are: fresh water shortages and contamination, soil degradation and loss, climate changes, ocean degradation. The onset of stealth disasters is incremental rather than abrupt. They may not unfold significantly during the course of one term of political office, but they are unfolding in our lifetime. We as individuals may or may not escape their consequences, but they will affect our children and grandchildren. If humans are familiar with stealth disasters at all, it is from a relatively local experience, e.g., flooding of the Mississippi or the Dust Bowl in the U

  16. Analysis of the occupants’ behavior related to natural ventilation

    DEFF Research Database (Denmark)

    Calì, Davide; Andersen, Rune Korsholm; Osterhage, Tanja


    The real energy performance of buildings depends both upon deterministic aspects (building'sphysics and engineering systems) and probabilistic aspects such as weather and occupantbehavior. Occupant behavior is usually not directly considered when calculating the expected energy performance...... of buildings. In fact, field test studies all over the world have shown discrepancies between expectation and real energy performances of buildings. This gap could be bridged, by embedding stochastic occupants’ behavior models within buildings’ energy performances simulation software. Within this work......, an established method to analyze the probability of a state change of the windows, based on logistic regression, was applied to monitored data (measured each minute) from two refurbished residential buildings. The weather as well as the five rooms of each of the 60 apartments located in the buildings were...

  17. Cognitive Therapy: Nature and Relation to Behavior Therapy - Republished Article. (United States)

    Beck, Aaron T


    Recent innovations in behavior modification have, for the most part, detoured around the role of cognitive processes in the production and alleviation of symptomatology. Although self-reports of private experiences are not verifiable by other observers, these introspective data provide a wealth of testable hypotheses. Repeated correlations of measures of inferred constructs with observable behaviors have yielded consistent findings in the predicted direction. Systematic study of self-reports suggests that an individual's belief systems, expectancies, and assumptions exert a strong influence on his state of well-being, as well as on his directly observable behavior. Applying a cognitive model, the clinician may usefully construe neurotic behavior in terms of the patient's idiosyncratic concepts of himself and of his animate and inanimate environment. The individual's belief systems may be grossly contradictory; i.e., he may simultaneously attach credence to both realistic and unrealistic conceptualizations of the same event or object. This inconsistency in beliefs may explain, for example, why an individual may react with fear to an innocuous situation even though he may concomitantly acknowledge that this fear is unrealistic. Cognitive therapy, based on cognitive theory, is designed to modify the individual's idiosyncratic, maladaptive ideation. The basic cognitive technique consists of delineating the individual's specific misconceptions, distortions, and maladaptive assumptions, and of testing their validity and reasonableness. By loosening the grip of his perseverative, distorted ideation, the patient is enabled to formulate his experiences more realistically. Clinical experience, as well as some experimental studies, indicate that such cognitive restructuring leads to symptom relief. Copyright © 2016. Published by Elsevier Ltd.

  18. AC and DC electrical behavior of MWCNT/epoxy nanocomposite near percolation threshold: Equivalent circuits and percolation limits (United States)

    Alizadeh Sahraei, Abolfazl; Ayati, Moosa; Baniassadi, Majid; Rodrigue, Denis; Baghani, Mostafa; Abdi, Yaser


    This study attempts to comprehensively investigate the effects of multi-walled carbon nanotubes (MWCNTs) on the AC and DC electrical conductivity of epoxy nanocomposites. The samples (0.2, 0.3, and 0.5 wt. % MWCNT) were produced using a combination of ultrason and shear mixing methods. DC measurements were performed by continuous measurement of the current-voltage response and the results were analyzed via a numerical percolation approach, while for the AC behavior, the frequency response was studied by analyzing phase difference and impedance in the 10 Hz to 0.2 MHz frequency range. The results showed that the dielectric parameters, including relative permittivity, impedance phase, and magnitude, present completely different behaviors for the frequency range and MWCNT weight fractions studied. To better understand the nanocomposites electrical behavior, equivalent electric circuits were also built for both DC and AC modes. The DC equivalent networks were developed based on the current-voltage curves, while the AC equivalent circuits were proposed by using an optimization problem according to the impedance magnitude and phase at different frequencies. The obtained equivalent electrical circuits were found to be highly useful tools to understand the physical mechanisms involved in MWCNT filled polymer nanocomposites.

  19. Is Applied Behavior Analysis Ready for Parapsychology? A Return to Natural Events. (United States)

    Ruben, Douglas H.; Ruben, Marilyn J.


    Argues for the application of behavioral methods including natural observations over reification in parapsychological research. Research methodology stressing the importance of observation, replication, and continuity in applied science is discussed. (Author/BL)

  20. Adsorption behavior of natural anthocyanin dye on mesoporous silica (United States)

    Kohno, Yoshiumi; Haga, Eriko; Yoda, Keiko; Shibata, Masashi; Fukuhara, Choji; Tomita, Yasumasa; Maeda, Yasuhisa; Kobayashi, Kenkichiro


    Because of its non-toxicity, naturally occurring anthocyanin is potentially suitable as a colorant for foods and cosmetics. To the wider use of the anthocyanin, the immobilization on the inorganic host for an easy handling as well as the improvement of the stability is required. This study is focused on the adsorption of significant amount of the natural anthocyanin dye onto mesoporous silica, and on the stability enhancement of the anthocyanin by the complexation. The anthocyanin has successfully been adsorbed on the HMS type mesoporous silica containing small amount of aluminum. The amount of the adsorbed anthocyanin has been increased by modifying the pore wall with n-propyl group to make the silica surface hydrophobic. The light fastness of the adsorbed anthocyanin has been improved by making the composite with the HMS samples containing aluminum, although the degree of the improvement is not so large. It has been proposed that incorporation of the anthocyanin molecule deep inside the mesopore is required for the further enhancement of the stability.

  1. Understanding Nature-Related Behaviors among Children through a Theory of Reasoned Action Approach (United States)

    Gotch, Chad; Hall, Troy


    The Theory of Reasoned Action has proven to be a valuable tool for predicting and understanding behavior and, as such, provides a potentially important basis for environmental education program design. This study used a Theory of Reasoned Action approach to examine a unique type of behavior (nature-related activities) and a unique population…

  2. Behavior of metal oxide nanoparticles in natural aqueous matrices (United States)

    Keller, A. A.; Zhou, D.; Wang, H.


    The increasing use of nanomaterials in consumer products that are exposed to environmental media has led to a need to understand their fate and transport. In particular, metal oxide (MeO) nanoparticles, such as TiO2, ZnO and CeO2, are increasingly incorporated into a wide range of products, from sunscreens to paints and other coatings, and catalysts. With regard to their transport, it is important to determine how far these nanoparticles will travel in different ambient waters, such as rivers, lakes and seawater. There have been a number of studies that have addressed the aggregation of different nanoparticles in simpler aqueous solutions. However, it is important to understand the combined effect of pH, ionic strength, ionic composition, NOM and other characteristics of the aqueous media in which the nanoparticles will be dispersed, which may result in either aggregation and settling, or stabilization and transport. This also affects the bioavailability of the nanomaterials, and the phase (water column or sediments) in which the bulk of the particles are likely to reside. For this study we considered several natural aqueous matrices, including seawater, freshwater, groundwater, rainwater and treated wastewater, as well as two different water matrices used in micro- and mesocosm studies of nanoparticle toxicity. We determined that the two most important water quality characteristics controlling the rate of aggregation, relatively independent of particle composition, are [NOM] and ionic strength.

  3. Stroke rehabilitation reaches a threshold.

    Directory of Open Access Journals (Sweden)

    Cheol E Han


    Full Text Available Motor training with the upper limb affected by stroke partially reverses the loss of cortical representation after lesion and has been proposed to increase spontaneous arm use. Moreover, repeated attempts to use the affected hand in daily activities create a form of practice that can potentially lead to further improvement in motor performance. We thus hypothesized that if motor retraining after stroke increases spontaneous arm use sufficiently, then the patient will enter a virtuous circle in which spontaneous arm use and motor performance reinforce each other. In contrast, if the dose of therapy is not sufficient to bring spontaneous use above threshold, then performance will not increase and the patient will further develop compensatory strategies with the less affected hand. To refine this hypothesis, we developed a computational model of bilateral hand use in arm reaching to study the interactions between adaptive decision making and motor relearning after motor cortex lesion. The model contains a left and a right motor cortex, each controlling the opposite arm, and a single action choice module. The action choice module learns, via reinforcement learning, the value of using each arm for reaching in specific directions. Each motor cortex uses a neural population code to specify the initial direction along which the contralateral hand moves towards a target. The motor cortex learns to minimize directional errors and to maximize neuronal activity for each movement. The derived learning rule accounts for the reversal of the loss of cortical representation after rehabilitation and the increase of this loss after stroke with insufficient rehabilitation. Further, our model exhibits nonlinear and bistable behavior: if natural recovery, motor training, or both, brings performance above a certain threshold, then training can be stopped, as the repeated spontaneous arm use provides a form of motor learning that further bootstraps performance and

  4. Sensitivity, child regulatory processes, and naturally occurring declines in antisocial behavior across childhood. (United States)

    Buck, Katharine Ann


    Despite considerable research on why antisocial behavior develops and interventions that reduce it, aspects of everyday family processes that may promote naturally occurring declines in antisocial behavior or that may result from such declines in most children without intervention are poorly understood. The current study explored family processes that may enable children to replace antisocial tendencies and the effects that declines in antisocial behavior may have on parenting and child regulatory processes. Longitudinal data from 1,022 children (54 months-6th grade) from the NICHD Study of Early Child Care and Youth Development were examined. Findings demonstrated that naturally occurring declines in antisocial behavior both predicted and were predicted by maternal sensitivity, emotion regulation, and social skills. These declines predicted but were not predicted by declines in hostile attributions. The data revealed multiple indirect paths, which highlight the complex nature of these variables across development.

  5. Cognitive-Behavioral Therapy: Nature and Relation to Non-Cognitive Behavioral Therapy. (United States)

    Lorenzo-Luaces, Lorenzo; Keefe, John R; DeRubeis, Robert J


    Since the introduction of Beck's cognitive theory of emotional disorders, and their treatment with psychotherapy, cognitive-behavioral approaches have become the most extensively researched psychological treatment for a wide variety of disorders. Despite this, the relative contribution of cognitive to behavioral approaches to treatment are poorly understood and the mechanistic role of cognitive change in therapy is widely debated. We critically review this literature, focusing on the mechanistic role of cognitive change across cognitive and behavioral therapies for depressive and anxiety disorders. Copyright © 2016. Published by Elsevier Ltd.

  6. Exploring the Influence of Nature Relatedness and Perceived Science Knowledge on Proenvironmental Behavior

    Directory of Open Access Journals (Sweden)

    Amanda Obery


    Full Text Available This study was undertaken to investigate the factors influencing proenvironmental behavior of individuals residing in the Northern Rocky Mountains (N = 267. Measures of relatedness to nature and perceived science knowledge were collected through a convenience sample approach using multiple avenues such as city email lists, organizational newsletters, and social media channels. Analysis of the data was conducted using both partial least squares and covariance based structural equation modeling to explore the relationships between the constructs. Additionally, qualitative definitions of proenvironmental behavior were investigated in order to address potential gaps between self-reported and observed behaviors. Quantitative findings show a renewed positive connection between science education, nature relatedness, and proenvironmental behaviors. Furthermore, qualitative findings suggest positive relationships between how publicly people are willing to share their passion for the outdoors and their willingness to engage in proenvironmental behaviors.

  7. Ingestive Behavior of Ovine Fed with Marandu Grass Silage Added with Naturally Dehydrated Brewery Residue. (United States)

    de Jesus Ferreira, Daniele; de Moura Zanine, Anderson; de Paula Lana, Rogério; Lima de Souza, Alexandre; Divino Ribeiro, Marinaldo; Mattos Negrão, Fagton; Castro, Wanderson José Rodrigues; Nunes Parente, Henrique; Valério Geron, Luiz Juliano; de Azevedo Câmara, Larissa Rodrigues


    The objective was to evaluate the ingestive behavior of ovine fed Marandu grass silage with dehydrated brewery residue added. The experiment had a completely randomized design with five treatments and four repetitions, with the treatments levels of inclusion being of 0, 10, 20, 30, and 40% natural matter of naturally dehydrated brewery residue for 36 hours to the marandu grass silage. 20 ovines were used and the experimental period was 21 days, 15 being for adaptation to diets. The use of brewery byproduct promoted quadratic effect (P Ingestion efficiency and rumination efficiency of dry matter (g DM/hour) were significant (P behavior, and NDF ingestion and rumination efficiency showed crescent linear behavior. The DM and NDF consumption expressed in kg/meal and in minutes/kg were also significant (P behavior. Rumination activity expressed in g DM and NDF/piece was influenced (P ingestive behavior.

  8. Strategic behavior and governance challenges in self-organized coupled natural-human systems (United States)

    Muneepeerakul, R.; Anderies, J. M.


    Successful and sustainable coupling of human societies and natural systems requires effective governance, which depends on the existence of proper infrastructure (both hard and soft). In recent decades, much attention has been paid to what has allowed many small-scale self-organized coupled natural-human systems around the world to persist for centuries, thanks to a large part to the work by Elinor Ostrom and colleagues. In this work, we mathematically operationalize a conceptual framework that is developed based on this body of work by way of a stylized model. The model captures the interplay between replicator dynamics within the population, dynamics of natural resources, and threshold characteristics of public infrastructure. The model analysis reveals conditions for long-term sustainability and collapse of the coupled systems as well as other tradeoffs and potential pitfalls in governing these systems.

  9. On Understanding the Human Nature of Good and Bad Behavior in Business: A Behavioral Ethics Approach

    NARCIS (Netherlands)

    D. de Cremer (David)


    textabstractThe numerous scandals in business, such as those at AIG, Tyco, WorldCom, Enron and Ahold, have made all of us concerned about the emergence of unethical and irresponsible behavior in organizations. Such widespread corruption in business and politics has, as result, prompted a growth of

  10. Cortical Local Field Potential Power Is Associated with Behavioral Detection of Near-threshold Stimuli in the Rat Whisker System: Dissociation between Orbitofrontal and Somatosensory Cortices. (United States)

    Rickard, Rachel E; Young, Andrew M J; Gerdjikov, Todor V


    There is growing evidence that ongoing brain oscillations may represent a key regulator of attentional processes and as such may contribute to behavioral performance in psychophysical tasks. OFC appears to be involved in the top-down modulation of sensory processing; however, the specific contribution of ongoing OFC oscillations to perception has not been characterized. Here we used the rat whiskers as a model system to further characterize the relationship between cortical state and tactile detection. Head-fixed rats were trained to report the presence of a vibrotactile stimulus (frequency = 60 Hz, duration = 2 sec, deflection amplitude = 0.01-0.5 mm) applied to a single vibrissa. We calculated power spectra of local field potentials preceding the onset of near-threshold stimuli from microelectrodes chronically implanted in OFC and somatosensory cortex. We found a dissociation between slow oscillation power in the two regions in relation to detection probability: Higher OFC but not somatosensory delta power was associated with increased detection probability. Furthermore, coherence between OFC and barrel cortex was reduced preceding successful detection. Consistent with the role of OFC in attention, our results identify a cortical network whose activity is differentially modulated before successful tactile detection.

  11. Influence of risky and protective behaviors connected with listening to music on hearing loss and the noise induced threshold shift among students of the Medical University of Bialystok

    Directory of Open Access Journals (Sweden)

    Beata Modzelewska


    Full Text Available Background . Currently, significant changes have occurred in the character of sound exposure, along with the properties of the group affected by it. Thus, primary care physicians have to keep in mind that a sizable group of young adults comprises groups in which the prevalence of hearing loss is increasing. Objectives . The goal of the following study was to determine the auditory ability of the students attending the Medical University in Bialystok and to analyze their risky and protective behaviors relating to music consumption. Material and methods . In total, 230 students (age: 18–26 years completed a questionnaire about general personal information and their music-listening habits. Thereafter, pure tone audiometry at standard frequencies (0.25 kHz–8 kHz was performed. Results . Hearing loss was more frequent in subjects who listened to music at higher volumes (‘very loud’ – 22.2%, ‘loud’ – 3.9%, ‘not very loud’ – 2.1%, ‘quiet’ – 9.1%, p = 0.046. Hearing loss was more prevalent among those students who were living in a city with more than 50,000 inhabitants before starting higher education compared to the remaining subjects (7.95% vs. 0.97%, p = 0.025. Conclusions . The study demonstrated that surprisingly few medical students suffer from hearing loss or a noise induced threshold shift. There is no correlation between risky behavior such as a lengthy daily duration of listening to music or the type of headphone used and hearing loss. Hearing screening tests connected with education are indicated in the group of young adults due to the accumulative character of hearing damage.

  12. Aggressive behavior of macaques, Macaca fascicularis (Raffles, 1821) on tourists at Kaliurang nature recreation forest, Yogyakarta




    Research was conducted in Kaliurang nature recreation forest area, in Gunung Merapi National Park, Yogyakarta. The research aim to investigate the proportion of aggressive behavior of monkeys [Macaca fascicularis (Raffles, 1821)] to tourists. Direct observation method was used to observe the monkeys behavior in the interaction to the tourists. And questioners were distributed to the tourists to know expectation of the tourists which related to the existence of the monkeys in that conservation...

  13. Integrating human and natural systems in community psychology: an ecological model of stewardship behavior. (United States)

    Moskell, Christine; Allred, Shorna Broussard


    Community psychology (CP) research on the natural environment lacks a theoretical framework for analyzing the complex relationship between human systems and the natural world. We introduce other academic fields concerned with the interactions between humans and the natural environment, including environmental sociology and coupled human and natural systems. To demonstrate how the natural environment can be included within CP's ecological framework, we propose an ecological model of urban forest stewardship action. Although ecological models of behavior in CP have previously modeled health behaviors, we argue that these frameworks are also applicable to actions that positively influence the natural environment. We chose the environmental action of urban forest stewardship because cities across the United States are planting millions of trees and increased citizen participation in urban tree planting and stewardship will be needed to sustain the benefits provided by urban trees. We used the framework of an ecological model of behavior to illustrate multiple levels of factors that may promote or hinder involvement in urban forest stewardship actions. The implications of our model for the development of multi-level ecological interventions to foster stewardship actions are discussed, as well as directions for future research to further test and refine the model.

  14. Behavioral changes in freestall-housed dairy cows with naturally occurring clinical mastitis

    DEFF Research Database (Denmark)

    Fogsgaard, Katrine Kop; Bennedsgaard, Torben Werner; Herskin, Mette S


    Dairy cows exhibit classic signs of sickness behavior during mastitis. However, knowledge about the consequences of naturally occurring mastitis in freestall-housed dairy cows, milked in automatic milking systems, is lacking. The aim of the present study was to describe the behavior of dairy cows...... after diagnosis and antibiotic treatment of mastitis. In the days before and after antibiotic treatment, the milking behavior, feeding, and activity were examined in 30 mastitic and 30 control Danish Holstein-Friesian cows kept in freestalls and milked by an automatic milking system. Sickness behavior...... was evident in the mastitic dairy cows and local clinical signs in the udder as well as behavioral changes persisted beyond the 3 d of antibiotic treatment. In the days before diagnosis and treatment, feed intake was reduced compared with the control animals. Although reduced by the antibiotic treatment...

  15. Studying the Genetics of Behavior and Evolution by Adaptation and Natural Selection. (United States)

    Silverman, Jules


    Provides an exercise designed to give students an appreciation for the genetic basis of behavior. Employs the phenomenon of glucose aversion as an example of evolution by mutation and accelerated natural selection, thereby revealing one of the ways in which organisms adapt to human interference. (DDR)

  16. A Preliminary Investigation into the Information Sharing Behavior of Social Media Users after a Natural Disaster (United States)

    Maruyama, Yukiko


    The paper provides the results of a preliminary investigation into the information sharing behavior of social media users after a natural disaster. The results indicate that users shared information that they thought victims would find useful. On the other hand, they reported that they usually do not or never share information considered useful to…

  17. Exploring the Influence of Nature Relatedness and Perceived Science Knowledge on Proenvironmental Behavior (United States)

    Obery, Amanda; Bangert, Arthur


    This study was undertaken to investigate the factors influencing proenvironmental behavior of individuals residing in the Northern Rocky Mountains (N = 267). Measures of relatedness to nature and perceived science knowledge were collected through a convenience sample approach using multiple avenues such as city email lists, organizational…

  18. Mechanical behavior of glass fiber polyester hybrid composite filled with natural fillers (United States)

    Gupta, G.; Gupta, A.; Dhanola, A.; Raturi, A.


    Now-a-days, the natural fibers and fillers from renewable natural resources offer the potential to act as a reinforcing material for polymer composite material alternative to the use of synthetic fiber like as; glass, carbon and other man-made fibers. Among various natural fibers and fillers like banana, wheat straw, rice husk, wood powder, sisal, jute, hemp etc. are the most widely used natural fibers and fillers due to its advantages like easy availability, low density, low production cost and reasonable physical and mechanical properties This research work presents the effect of natural fillers loading with 5%, 10% and 15% on mechanical behavior of polyester based hybrid composites. The result of test depicted that hybrid composite has far better properties than single fibre glass reinforced composite under impact and flexural loads. However it is found that the hybrid composite have better strength as compared to single glass fibre composites.

  19. Do termites avoid carcasses? Behavioral responses depend on the nature of the carcasses.

    Directory of Open Access Journals (Sweden)

    Kok-Boon Neoh

    Full Text Available BACKGROUND: Undertaking behavior is a significant adaptation to social life in enclosed nests. Workers are known to remove dead colony members from the nest. Such behavior prevents the spread of pathogens that may be detrimental to a colony. To date, little is known about the ethological aspects of how termites deal with carcasses. METHODOLOGY AND PRINCIPAL FINDINGS: In this study, we tested the responses to carcasses of four species from different subterranean termite taxa: Coptotermes formosanus Shiraki and Reticulitermes speratus (Kolbe (lower termites and Microcerotermes crassus Snyder and Globitermes sulphureus Haviland (higher termites. We also used different types of carcasses (freshly killed, 1-, 3-, and 7-day-old, and oven-killed carcasses and mutilated nestmates to investigate whether the termites exhibited any behavioral responses that were specific to carcasses in certain conditions. Some behavioral responses were performed specifically on certain types of carcasses or mutilated termites. C. formosanus and R. speratus exhibited the following behaviors: (1 the frequency and time spent in antennating, grooming, and carcass removal of freshly killed, 1-day-old, and oven-killed carcasses were high, but these behaviors decreased as the carcasses aged; (2 the termites repeatedly crawled under the aging carcass piles; and (3 only newly dead termites were consumed as a food source. In contrast, M. crassus and G. sulphureus workers performed relatively few behavioral acts. Our results cast a new light on the previous notion that termites are necrophobic in nature. CONCLUSION: We conclude that the behavioral response towards carcasses depends largely on the nature of the carcasses and termite species, and the response is more complex than was previously thought. Such behavioral responses likely are associated with the threat posed to the colony by the carcasses and the feeding habits and nesting ecology of a given species.

  20. Investigation of Thermal Behavior for Natural Fibres Reinforced Epoxy using Thermogravimetric and Differential Scanning Calorimetric Analysis

    Directory of Open Access Journals (Sweden)

    Fauzi F.A.


    Full Text Available This paper presented the research works on the investigation of the thermal behavior of the natural fibres; i.e. pineapple leaf fibre, kenaf fibre and mengkuang fibres reinforced epoxy. The thermogravimetric analysis and differential scanning calorimetric analysis were used to measure the thermal behavior of the treated and untreated pineapple, kenaf and mengkuang fibres reinforced epoxy. The samples for both analysis were subjected to maximum temperature 600°C at the heating rate of 10°C/min. The results showed that the treated fibres show higher maximum peak temperature as compared to the untreated fibres. Additionally, the glass transition temperature showed a lower value for all treated fibre. It can be concluded that investigation of thermal properties of these natural fibres could improve the utilization of natural fibre composites in various applications i.e. sports applications.

  1. Regulation of hippocampal synaptic plasticity thresholds and changes in exploratory and learning behavior in dominant negative NPR-B mutant rats

    Directory of Open Access Journals (Sweden)

    Gleb eBarmashenko


    Full Text Available The second messenger cyclic GMP affects synaptic transmission and modulates synaptic plasticity and certain types of learning and memory processes. The impact of the natriuretic peptide receptor B (NPR-B and its ligand C-type natriuretic peptide (CNP, one of several cGMP producing signalling systems, on hippocampal synaptic plasticity and learning is, however, less well understood. We have previously shown that the NPR-B ligand CNP increases the magnitude of long-term depression (LTD in hippocampal area CA1, while reducing the induction of long-term potentiation (LTP. We have extended this line of research to show that bidirectional plasticity is affected in the opposite way in rats expressing a dominant-negative mutant of NPR-B (NSE-NPR-BdeltaKC lacking the intracellular guanylyl cyclase domain under control of a promoter for neuron-specific enolase. The brain cells of these transgenic rats express functional dimers of the NPR-B receptor containing the dominant-negative NPR-BdeltaKC mutant, and therefore show decreased CNP-stimulated cGMP-production in brain membranes. The NPR-B transgenic rats display enhanced LTP but reduced LTD in hippocampal slices. When the frequency-dependence of synaptic modification to afferent stimulation in the range of 1-100 Hz was assessed in transgenic rats the threshold for LTP induction was raised, but LTD induction was facilitated. In parallel, NPR-BdeltaKC rats exhibited an enhancement in exploratory and learning behavior. These results indicate that bidirectional plasticity and learning and memory mechanism are affected in transgenic rats expressing a dominant-negative mutant of NPR-B. Our data substantiate the hypothesis that NPR-B-dependent cGMP signalling has a modulatory role for synaptic information storage and learning.

  2. Aggressive behavior of macaques, Macaca fascicularis (Raffles, 1821 on tourists at Kaliurang nature recreation forest, Yogyakarta

    Directory of Open Access Journals (Sweden)



    Full Text Available Research was conducted in Kaliurang nature recreation forest area, in Gunung Merapi National Park, Yogyakarta. The research aim to investigate the proportion of aggressive behavior of monkeys [Macaca fascicularis (Raffles, 1821] to tourists. Direct observation method was used to observe the monkeys behavior in the interaction to the tourists. And questioners were distributed to the tourists to know expectation of the tourists which related to the existence of the monkeys in that conservation area. Analyses of the interactions suggest that monkeys respond differentially to tourists according to the age/sex classes involved. Additionally, adult and subadult male monkeys participated in more aggressive behaviors than expected, while adult female monkeys and immature participated in such behaviors less than expected. These variations in interaction patterns between monkeys and tourists may have substantial implications for management issues and that the potential for gaining or reducing the tourists to visit in that forest recreation.

  3. Plutonium - its behavior in natural-water systems and assimilation by man

    International Nuclear Information System (INIS)

    Larsen, R.P.; Nelson, D.M.; Bhattacharyya, M.H.; Oldham, R.D.


    There are a number of factors which must be considered in establishing whether or not the inadvertent intrusion of a sizable amount of plutonium-bearing material into a natural-water system may have a significant impact on the health of those individuals who use that system as a drinking-water resource. These factors include the chemical form(s) and solubility of plutonium in natural waters, its behavior in relation to natural processes (geochemical and biological), its fate in water-treatment systems, and its uptake by man from drinking water. From the results obtained of the behavior in natural-water systems, it appears that (1) the chemical forms of plutonium dissolved in natural waters are Pu(IV) and Pu(V), (2) the soluble plutonium in many waters is bound to the organic constituents which probably enhance plutonium solubility, (3) the natural process responsible for the removal of plutonium from water is adsorption onto sediments, and (4) in water-treatment systems, soluble plutonium is oxidized to the VI state and this form is not removed. From investigations of gastrointestinal absorption, it appears that the value for f 1 , the fraction transferred from the gut to blood, is greater than 1 x 10 - 3 and may be as high as 2 x 10 - 1

  4. Ingestive Behavior of Ovine Fed with Marandu Grass Silage Added with Naturally Dehydrated Brewery Residue

    Directory of Open Access Journals (Sweden)

    Daniele de Jesus Ferreira


    Full Text Available The objective was to evaluate the ingestive behavior of ovine fed Marandu grass silage with dehydrated brewery residue added. The experiment had a completely randomized design with five treatments and four repetitions, with the treatments levels of inclusion being of 0, 10, 20, 30, and 40% natural matter of naturally dehydrated brewery residue for 36 hours to the marandu grass silage. 20 ovines were used and the experimental period was 21 days, 15 being for adaptation to diets. The use of brewery byproduct promoted quadratic effect (P<0.05 for the consumption of dry matter with maximum point value estimated at adding 23.25% additive. Ingestion efficiency and rumination efficiency of dry matter (g DM/hour were significant (P<0.05, by quadratic behavior, and NDF ingestion and rumination efficiency showed crescent linear behavior. The DM and NDF consumption expressed in kg/meal and in minutes/kg were also significant (P<0.05, showing quadratic behavior. Rumination activity expressed in g DM and NDF/piece was influenced (P<0.05 by the adding of brewery residue in marandu grass silage in quadratic way, with maximum value estimated of 1.57 g DM/bolus chewed in inclusion of 24.72% additive in grass silage. The conclusion is that intermediary levels adding of 20 to 25% dehydrated brewery residue affects certain parameters of ingestive behavior.

  5. Weakly electric fish display behavioral responses to envelopes naturally occurring during movement: implications for neural processing. (United States)

    Metzen, Michael G; Chacron, Maurice J


    How the brain processes natural sensory input remains an important and poorly understood problem in neuroscience. The efficient coding hypothesis asserts that the brain's coding strategies are adapted to the statistics of natural stimuli in order to efficiently process them, thereby optimizing their perception by the organism. Here we examined whether gymnotiform weakly electric fish displayed behavioral responses that are adapted to the statistics of the natural electrosensory envelopes. Previous studies have shown that the envelopes resulting from movement tend to consist of low (Hz) temporal frequencies and are behaviorally relevant whereas those resulting from social interactions consist of higher (>1 Hz) temporal frequencies that can thus mask more behaviorally relevant signals. We found that the self-generated electric organ discharge frequency follows the detailed time course of the envelope around a mean value that is positively offset with respect to its baseline value for temporal frequencies between 0.001 Hz and 1 Hz. The frequency-following component of this behavioral response decreased in magnitude as a power law as a function of the envelope frequency and was negligible for envelope frequencies above 1 Hz. In contrast, the offset component was relatively constant and somewhat increased for envelope frequencies above 1 Hz. Thus, our results show that weakly electric fish display behavioral responses that track the detailed time course of low but not high frequency envelope stimuli. Furthermore, we found that the magnitude of the frequency-following behavioral response matches, in a one-to-one fashion, the spectral power of natural second-order stimulus attributes observed during movement. Indeed, both decayed as a power law with the same exponent for temporal frequencies spanning three orders of magnitude. Thus, our findings suggest that the neural coding strategies used by weakly electric fish perceive the detailed time course of movement envelopes

  6. Wear Behavior of Ceramic CAD/CAM Crowns and Natural Antagonists


    Naumova, Ella A.; Schneider, Stephan; Arnold, Wolfgang H.; Piwowarczyk, Andree


    Objective: Evaluation of wear behavior of computer-aided design/computer-aided manufacturing (CAD/CAM) crowns from various restorative materials and natural antagonists. Method: Full CAD/CAM crowns fabricated with nanoceramic resin (Lava Ultimate (LU)), a glass ceramic in a resin interpenetrating matrix (Vita Enamic (VE)) and a lithium silicate reinforced ceramic enriched with zirconia (Vita Suprinity (VS)) were cemented on human molars. The crown and antagonists were subjected to simulated c...

  7. Baseline Behavior of Pilot Whales and their Responses to Playback of Anthropogenic and Natural Sounds (United States)


    the playbacks to half the duration of the playbacks used in the Mediterranean , for a playback duration of 7.5 minutes. While we did not collect...Tíscar, S., Verborgh, P., Esteban-Pavo, R., Pérez, S., Minvielle-Sebastia, L. and Guinet, C. (2008b). Diet of the social groups of long-finned pilot...investigates the social ecology and baseline behavior of pilot whales, and responses to controlled exposures of anthropogenic and natural sounds. The ultimate

  8. Evaluation of Knock Behavior for Natural Gas - Gasoline Blends in a Light Duty Spark Ignited Engine

    Energy Technology Data Exchange (ETDEWEB)

    Pamminger, Michael [Argonne National Lab. (ANL), Argonne, IL (United States); Sevik, James [Argonne National Lab. (ANL), Argonne, IL (United States); Scarcelli, Riccardo [Argonne National Lab. (ANL), Argonne, IL (United States); Wallner, Thomas [Argonne National Lab. (ANL), Argonne, IL (United States); Wooldridge, Steven [Ford Motor Co., Detroit, MI (United States); Boyer, Brad [Ford Motor Co., Detroit, MI (United States); Hall, Carrie M. [Illinois Inst. of Technology, Chicago, IL (United States)


    The compression ratio is a strong lever to increase the efficiency of an internal combustion engine. However, among others, it is limited by the knock resistance of the fuel used. Natural gas shows a higher knock resistance compared to gasoline, which makes it very attractive for use in internal combustion engines. The current paper describes the knock behavior of two gasoline fuels, and specific incylinder blend ratios with one of the gasoline fuels and natural gas. The engine used for these investigations is a single cylinder research engine for light duty application which is equipped with two separate fuel systems. Both fuels can be used simultaneously which allows for gasoline to be injected into the intake port and natural gas to be injected directly into the cylinder to overcome the power density loss usually connected with port fuel injection of natural gas. Adding natural gas at wide open throttle helps to reduce knock mitigating measures and increases the efficiency and power density compared to the other gasoline type fuels with lower knock resistance. The used methods, knock intensity and number of pressure waves, do not show significant differences in knock behavior for the natural gas - gasoline blends compared to the gasoline type fuels. A knock integral was used to describe the knock onset location of the fuels tested. Two different approaches were used to determine the experimental knock onset and were compared to the knock onset delivered by the knock integral (chemical knock onset). The gasoline type fuels show good agreement between chemical and experimental knock onset. However, the natural gas -gasoline blends show higher discrepancies comparing chemical and experimental knock onset.

  9. Single Phase Natural Circulation Behaviors of the Integral Type Marine Reactor Simulator under Rolling Motion Condition

    Directory of Open Access Journals (Sweden)

    Hou-jun Gong


    Full Text Available During operation in the sea the reactor natural circulation behaviors are affected by ship rolling motion. The development of an analysis code and the natural circulation behaviors of a reactor simulator under rolling motion are described in this paper. In the case of rolling motion, the primary coolant flow rates in the hot legs and heating channels oscillated periodically, and the amplitude of flow rate oscillation was in direct proportion to rolling amplitude, but in inverse proportion to rolling period. The total mass flow rate also oscillated with half the rolling period, and the average total mass flow rate was less than that in steady state. In the natural circulation under a rolling motion, the flow rate oscillations in the hot legs were controlled by the tangential force; however, the mass flow rate oscillations in the total natural circulation and the heating channels were a result of the combined action of the change of inclination angle, flow resistance, and the extra force arising from the rolling motion. The extra tangential force brought about intense flow rate oscillations in the hot legs, which resulted in increasing total flow resistance; however the extra centrifugal force played a role in increasing thermal driving head.

  10. Prospective Analysis of Behavioral Economic Predictors of Stable Moderation Drinking Among Problem Drinkers Attempting Natural Recovery. (United States)

    Tucker, Jalie A; Cheong, JeeWon; Chandler, Susan D; Lambert, Brice H; Pietrzak, Brittney; Kwok, Heather; Davies, Susan L


    As interventions have expanded beyond clinical treatment to include brief interventions for persons with less severe alcohol problems, predicting who can achieve stable moderation drinking has gained importance. Recent behavioral economic (BE) research on natural recovery has shown that active problem drinkers who allocate their monetary expenditures on alcohol and saving for the future over longer time horizons tend to have better subsequent recovery outcomes, including maintenance of stable moderation drinking. This study compared the predictive utility of this money-based "Alcohol-Savings Discretionary Expenditure" (ASDE) index with multiple BE analogue measures of behavioral impulsivity and self-control, which have seldom been investigated together, to predict outcomes of natural recovery attempts. Community-dwelling problem drinkers, enrolled shortly after stopping abusive drinking without treatment, were followed prospectively for up to a year (N = 175 [75.4% male], M age = 50.65 years). They completed baseline assessments of preresolution drinking practices and problems, analogue behavioral choice tasks (Delay Discounting, Melioration-Maximization, and Alcohol Purchase Tasks), and a Timeline Followback interview including expenditures on alcohol compared to voluntary savings (ASDE index) during the preresolution year. Multinomial logistic regression models showed that, among the BE measures, only the ASDE index predicted stable moderation drinking compared to stable abstinence or unstable resolutions involving relapse. As hypothesized, stable moderation was associated with more balanced preresolution allocations to drinking and savings (odds ratio = 1.77, 95% confidence interval = 1.02 to 3.08, p behavior regulation processes than abstinence. The ASDE's unique predictive utility may rest on its comprehensive representation of contextual elements to support this patterning of behavioral allocation. Stable low-risk drinking, but not abstinence

  11. A review of studies examining the nature of selection-based and topography-based verbal behavior


    Potter, Bill; Brown, Deborah L.


    Selection-based (SB) verbal behavior, in most general terms, consists of selecting stimuli from an array, which presumably has some effect on a listener. Topography-based (TB) verbal behavior consists of responses with unique topographies (e.g. speaking, signing, writing) which is also presumed to have some effect on a listener. This article reviews research examining the nature of these two types of verbal behavior. Overall, TB verbal behavior appears to be more easily acquired and may also ...

  12. Threshold quantum cryptography

    International Nuclear Information System (INIS)

    Tokunaga, Yuuki; Okamoto, Tatsuaki; Imoto, Nobuyuki


    We present the concept of threshold collaborative unitary transformation or threshold quantum cryptography, which is a kind of quantum version of threshold cryptography. Threshold quantum cryptography states that classical shared secrets are distributed to several parties and a subset of them, whose number is greater than a threshold, collaborates to compute a quantum cryptographic function, while keeping each share secretly inside each party. The shared secrets are reusable if no cheating is detected. As a concrete example of this concept, we show a distributed protocol (with threshold) of conjugate coding

  13. Analyzing the Impact of Residential Building Attributes, Demographic and Behavioral Factors on Natural Gas Usage

    Energy Technology Data Exchange (ETDEWEB)

    Livingston, Olga V.; Cort, Katherine A.


    study attempts to bridge that gap by analyzing behavioral data and investigate the applicability of additive nonparametric regression to this task. This study evaluates the impact of 31 regressors on residential natural gas usage. The regressors include weather, economic variables, demographic and behavioral characteristics, and building attributes related to energy use. In general, most of the regression results were in line with previous engineering and economic studies in this area. There were, however, some counterintuitive results, particularly with regard to thermostat controls and behaviors. There are a number of possible reasons for these counterintuitive results including the inability to control for regional climate variability due to the data sanitization (to prevent identification of respondents), inaccurate data caused by to self-reporting, and the fact that not all relevant behavioral variables were included in the data set, so we were not able to control for them in the study. The results of this analysis could be used as an in-sample prediction for approximating energy demand of a residential building whose characteristics are described by the regressors in this analysis, but a certain combination of their particular values does not exist in the real world. In addition, this study has potential applications for benefit-cost analysis of residential upgrades and retrofits under a fixed budget, because the results of this study contain information on how natural gas consumption might change once a particular characteristic or attribute is altered. Finally, the results of this study can help establish a relationship between natural gas consumption and changes in behavior of occupants.

  14. Natural variation in early parental care correlates with social behaviors in adolescent prairie voles (Microtus ochrogaster

    Directory of Open Access Journals (Sweden)

    Allison M Perkeybile


    Full Text Available Natural variation in early parental care may contribute to long-term changes in behavior in the offspring. Here we investigate the role of variable early care in biparental prairie voles (Microtus ochrogaster. Total amounts of parental care were initially quantified for 24 breeder pairs and pairs were ranked in relation to one another based on total contact. Consistency in key components of care suggested a trait-like quality to parental care. Based on this ranking, breeder pairs from the top (high-contact and bottom (low-contact quartiles were selected to produce high- and low-contact offspring to investigate adolescent behavior after varying early care. Parental care of subject offspring was again observed postnatally. Offspring of high-contact parents spent more time passively nursing and received more paternal nonhuddling contact while low-contact offspring spent more time actively nursing and received more paternal huddling and pseudohuddling in the first postnatal days. Low-contact offspring also displayed faster rates of development on a number of physical markers. Post-weaning, offspring were evaluated on anxiety-like behavior, social behavior and pre-pulse inhibition to a tactile and an acoustic startle. High-contact offspring spent more time sniffing a juvenile and less time autogrooming. With an infant, high-contact offspring spent more time in nonhuddling contact and less time autogrooming and retrieving than did low-contact offspring. Considering sexes separately, high-contact females spent more time sniffing a novel juvenile than low-contact females. High-contact males spent more time in nonhuddling contact with an infant than low-contact males; while low-contact females retrieved infants more than high-contact females. In both measures of social behavior, high-contact males spent less time autogrooming than low-contact males. These results suggest a relationship between early-life care and differences in social behavior in

  15. Avoid, attack or do both? Behavioral and physiological adaptations in natural enemies faced with novel hosts

    Directory of Open Access Journals (Sweden)

    Brown Sam P


    Full Text Available Abstract Background Confronted with well-defended, novel hosts, should an enemy invest in avoidance of these hosts (behavioral adaptation, neutralization of the defensive innovation (physiological adaptation or both? Although simultaneous investment in both adaptations may first appear to be redundant, several empirical studies have suggested a reinforcement of physiological resistance to host defenses with additional avoidance behaviors. To explain this paradox, we develop a mathematical model describing the joint evolution of behavioral and physiological adaptations on the part of natural enemies to their host defenses. Our specific goals are (i to derive the conditions that may favor the simultaneous investment in avoidance and physiological resistance and (ii to study the factors that govern the relative investment in each adaptation mode. Results Our results show that (i a simultaneous investment may be optimal if the fitness costs of the adaptive traits are accelerating and the probability of encountering defended hosts is low. When (i holds, we find that (ii the more that defended hosts are rare and/or spatially aggregated, the more behavioral adaptation is favored. Conclusion Despite their interference, physiological resistance to host defensive innovations and avoidance of these same defenses are two strategies in which it may be optimal for an enemy to invest in simultaneously. The relative allocation to each strategy greatly depends on host spatial structure. We discuss the implications of our findings for the management of invasive plant species and the management of pest resistance to new crop protectants or varieties.

  16. SAS3A analysis of natural convection boiling behavior in the Sodium Boiling Test Facility

    International Nuclear Information System (INIS)

    Klein, G.A.


    An analysis of natural convection boiling behavior in the Sodium Boiling Test (SBT) Facility has been performed using the SAS3A computer code. The predictions from this analysis indicate that stable boiling can be achieved for extensive periods of time for channel powers less than 1.4 kW and indicate intermittent dryout at higher powers up to at least 1.7 kW. The results of this anaysis are in reasonable agreement with the SBT Facility test results

  17. Theory of threshold phenomena

    International Nuclear Information System (INIS)

    Hategan, Cornel


    Theory of Threshold Phenomena in Quantum Scattering is developed in terms of Reduced Scattering Matrix. Relationships of different types of threshold anomalies both to nuclear reaction mechanisms and to nuclear reaction models are established. Magnitude of threshold effect is related to spectroscopic factor of zero-energy neutron state. The Theory of Threshold Phenomena, based on Reduced Scattering Matrix, does establish relationships between different types of threshold effects and nuclear reaction mechanisms: the cusp and non-resonant potential scattering, s-wave threshold anomaly and compound nucleus resonant scattering, p-wave anomaly and quasi-resonant scattering. A threshold anomaly related to resonant or quasi resonant scattering is enhanced provided the neutron threshold state has large spectroscopic amplitude. The Theory contains, as limit cases, Cusp Theories and also results of different nuclear reactions models as Charge Exchange, Weak Coupling, Bohr and Hauser-Feshbach models. (author)

  18. Study of Gaussian Doped Double Gate JunctionLess (GD-DG-JL) transistor including source drain depletion length: Model for sub-threshold behavior (United States)

    Kumari, Vandana; Kumar, Ayush; Saxena, Manoj; Gupta, Mridula


    The sub-threshold model formulation of Gaussian Doped Double Gate JunctionLess (GD-DG-JL) FET including source/drain depletion length is reported in the present work under the assumption that the ungated regions are fully depleted. To provide deeper insight into the device performance, the impact of gaussian straggle, channel length, oxide and channel thickness and high-k gate dielectric has been studied using extensive TCAD device simulation.

  19. Crossing the threshold (United States)

    Bush, John; Tambasco, Lucas


    First, we summarize the circumstances in which chaotic pilot-wave dynamics gives rise to quantum-like statistical behavior. For ``closed'' systems, in which the droplet is confined to a finite domain either by boundaries or applied forces, quantum-like features arise when the persistence time of the waves exceeds the time required for the droplet to cross its domain. Second, motivated by the similarities between this hydrodynamic system and stochastic electrodynamics, we examine the behavior of a bouncing droplet above the Faraday threshold, where a stochastic element is introduced into the drop dynamics by virtue of its interaction with a background Faraday wave field. With a view to extending the dynamical range of pilot-wave systems to capture more quantum-like features, we consider a generalized theoretical framework for stochastic pilot-wave dynamics in which the relative magnitudes of the drop-generated pilot-wave field and a stochastic background field may be varied continuously. We gratefully acknowledge the financial support of the NSF through their CMMI and DMS divisions.

  20. Detection thresholds of macaque otolith afferents. (United States)

    Yu, Xiong-Jie; Dickman, J David; Angelaki, Dora E


    The vestibular system is our sixth sense and is important for spatial perception functions, yet the sensory detection and discrimination properties of vestibular neurons remain relatively unexplored. Here we have used signal detection theory to measure detection thresholds of otolith afferents using 1 Hz linear accelerations delivered along three cardinal axes. Direction detection thresholds were measured by comparing mean firing rates centered on response peak and trough (full-cycle thresholds) or by comparing peak/trough firing rates with spontaneous activity (half-cycle thresholds). Thresholds were similar for utricular and saccular afferents, as well as for lateral, fore/aft, and vertical motion directions. When computed along the preferred direction, full-cycle direction detection thresholds were 7.54 and 3.01 cm/s(2) for regular and irregular firing otolith afferents, respectively. Half-cycle thresholds were approximately double, with excitatory thresholds being half as large as inhibitory thresholds. The variability in threshold among afferents was directly related to neuronal gain and did not depend on spike count variance. The exact threshold values depended on both the time window used for spike count analysis and the filtering method used to calculate mean firing rate, although differences between regular and irregular afferent thresholds were independent of analysis parameters. The fact that minimum thresholds measured in macaque otolith afferents are of the same order of magnitude as human behavioral thresholds suggests that the vestibular periphery might determine the limit on our ability to detect or discriminate small differences in head movement, with little noise added during downstream processing.

  1. Contributions of vitreous natural analogs to the investigation of long-term nuclear glass behavior

    International Nuclear Information System (INIS)

    Techer, I.


    This study assesses the extend of the analogy between the alteration behavior in water and in a moist clay environment of aluminosilicate volcanic glass and alumino-borosilicate nuclear containment glass. Basaltic glass alteration in water initially occurs by hydrolysis processes with an activation energy on the order of 73 kJ.mol -1 . As the reaction progresses, the alteration rate drops by over four orders of magnitude from the initial rate r 0 , The alteration kinetics are not governed by the alteration solution chemistry alone, the glass alteration film appears to have a major role as a diffusion barrier limiting the transfer of reaction species and products. All these aspects highlight the behavioral analogy between basaltic glass and nuclear borosilicate glass in aqueous media. Conversely, the alteration reaction of obsidian-type volcanic glass involves other mechanisms than those governing the dissolution of borosilicate glass. Basaltic glass alteration is also examined in the presence of a clay environmental material, in a study of the natural basaltic glass and argillaceous pelites system of the Salagou basin in southern France, in an approach combining mineralogical, chemical and isotopic data to assess the interactions between a basaltic glass and the argillaceous pelites. Laboratory leach test results with basaltic glass and measured data for the Salagou glass in its natural environment are modeled using a code implementing a kinetic law coupling diffusive transfer of dissolved silica with a reaction affinity law. (author)

  2. Bond behavior of steel bars embedded in concretes made with natural lightweight aggregates

    Directory of Open Access Journals (Sweden)

    Mohammad Jamal Al-Shannag


    Full Text Available The bond properties of reinforcing steel bars embedded in structural concrete made with locally available natural lightweight aggregates, was studied using pull-out tests on cubic specimens of 150 × 150 × 150 mm. A series of 30 specimens were cast considering the effect of bar diameter, and concrete compressive strength. Test results showed that the load-slip behavior of the structural lightweight concretes (SLWCs investigated compare reasonably well with the behavior of concretes reported in the literature, and is dependent upon the compressive strength, bar size and the embedded length. The bond strength of SLWCs increased with a higher concrete compression strength but decreased as the bar diameter was increased. Comparisons of measured bond strength with the ACI bond equations showed that for all cases the experimental bond strength values were higher than the design ones. However, the results indicate use of caution when applying bond formulas of normal weight concrete to lightweight concretes. Furthermore, this study has revealed that locally available natural lightweight aggregates could be considered as a promising, and cost effective material for designing reinforced concrete members.

  3. Neural processing, perception, and behavioral responses to natural chemical stimuli by fish and crustaceans. (United States)

    Derby, Charles D; Sorensen, Peter W


    This manuscript reviews the chemical ecology of two of the major aquatic animal models, fish and crustaceans, in the study of chemoreception. By necessity, it is restricted in scope, with most emphasis placed on teleost fish and decapod crustaceans. First, we describe the nature of the chemical world perceived by fish and crustaceans, giving examples of the abilities of these animals to analyze complex natural odors. Fish and crustaceans share the same environments and have evolved some similar chemosensory features: the ability to detect and discern mixtures of small metabolites in highly variable backgrounds and to use this information to identify food, mates, predators, and habitat. Next, we give examples of the molecular nature of some of these natural products, including a description of methodologies used to identify them. Both fish and crustaceans use their olfactory and gustatory systems to detect amino acids, amines, and nucleotides, among many other compounds, while fish olfactory systems also detect mixtures of sex steroids and prostaglandins with high specificity and sensitivity. Third, we discuss the importance of plasticity in chemical sensing by fish and crustaceans. Finally, we conclude with a description of how natural chemical stimuli are processed by chemosensory systems. In both fishes and crustaceans, the olfactory system is especially adept at mixture discrimination, while gustation is well suited to facilitate precise localization and ingestion of food. The behaviors of both fish and crustaceans can be defined by the chemical worlds in which they live and the abilities of their nervous systems to detect and identify specific features in their domains. An understanding of these worlds and the sensory systems that provide the animals with information about them provides insight into the chemical ecology of these species.

  4. Enlightening Butterfly Conservation Efforts: The Importance of Natural Lighting for Butterfly Behavioral Ecology and Conservation

    Directory of Open Access Journals (Sweden)

    Brett M Seymoure


    Full Text Available Light is arguably the most important abiotic factor for living organisms. Organisms evolved under specific lighting conditions and their behavior, physiology, and ecology are inexorably linked to light. Understanding light effects on biology could not be more important as present anthropogenic effects are greatly changing the light environments in which animals exist. The two biggest anthropogenic contributors changing light environments are: (1 anthropogenic lighting at night (i.e., light pollution; and (2 deforestation and the built environment. I highlight light importance for butterfly behavior, physiology, and ecology and stress the importance of including light as a conservation factor for conserving butterfly biodiversity. This review focuses on four parts: (1 Introducing the nature and extent of light. (2 Visual and non-visual light reception in butterflies. (3 Implications of unnatural lighting for butterflies across several different behavioral and ecological contexts. (4. Future directions for quantifying the threat of unnatural lighting on butterflies and simple approaches to mitigate unnatural light impacts on butterflies. I urge future research to include light as a factor and end with the hopeful thought that controlling many unnatural light conditions is simply done by flipping a switch.

  5. Toward brain correlates of natural behavior: fMRI during violent video games. (United States)

    Mathiak, Klaus; Weber, René


    Modern video games represent highly advanced virtual reality simulations and often contain virtual violence. In a significant amount of young males, playing video games is a quotidian activity, making it an almost natural behavior. Recordings of brain activation with functional magnetic resonance imaging (fMRI) during gameplay may reflect neuronal correlates of real-life behavior. We recorded 13 experienced gamers (18-26 years; average 14 hrs/week playing) while playing a violent first-person shooter game (a violent computer game played in self-perspective) by means of distortion and dephasing reduced fMRI (3 T; single-shot triple-echo echo-planar imaging [EPI]). Content analysis of the video and sound with 100 ms time resolution achieved relevant behavioral variables. These variables explained significant signal variance across large distributed networks. Occurrence of violent scenes revealed significant neuronal correlates in an event-related design. Activation of dorsal and deactivation of rostral anterior cingulate and amygdala characterized the mid-frontal pattern related to virtual violence. Statistics and effect sizes can be considered large at these areas. Optimized imaging strategies allowed for single-subject and for single-trial analysis with good image quality at basal brain structures. We propose that virtual environments can be used to study neuronal processes involved in semi-naturalistic behavior as determined by content analysis. Importantly, the activation pattern reflects brain-environment interactions rather than stimulus responses as observed in classical experimental designs. We relate our findings to the general discussion on social effects of playing first-person shooter games. (c) 2006 Wiley-Liss, Inc.

  6. Mechanical properties, morphology, and hydrolytic degradation behavior of polylactic acid / natural rubber blends (United States)

    Buys, Y. F.; Aznan, A. N. A.; Anuar, H.


    Due to its biodegradability and renewability, polylactic acid (PLA) has been receiving enormous attention as a potential candidate to replace petroleum based polymers. However, PLA has limitation due to its inherent brittleness. In order to overcome this limitation, blending PLA with elastomeric materials such as natural rubber (NR) are commonly reported. In previous, several researches on PLA/NR blend had been reported, with most of them evaluated the mechanical properties. On the other hand, study of degradation behavior is significance of importance, as controlling materials degradation is required in some applications. This research studied the effect of blend composition on mechanical properties, morphology development, and hydrolytic degradation behavior of PLA/NR blends. Various compositions of PLA/NR blends were prepared by melt blending technique. Tensile test and impact test of the blends were performed to evaluate the mechanical properties. Addition of NR improved the elongation at break and impact strength of the blends, but reduced the tensile strength and stiffness of the specimens. Dynamic Mechanical Analysis (DMA) measurements of the blends displayed two peaks at temperature -70˚C which corresponded to T g of NR and 65˚C which corresponded to T g of PLA. Field Emission Scanning Electron Microscopy (FE-SEM) micrograph of 70/30 PLA/NR specimen also showed two distinct phases, which lead to indication that PLA/NR blends are immiscible. Hydrolytic degradation behavior was evaluated by measuring the remaining weight of the samples immersed in sodium hydroxide solution for a predetermined times. It was shown that the degradation behavior of PLA/NR blends is affected by composition of the blends, with 100 PLA and 70/30 PLA/NR blend showed the fastest degradation rate and 100 NR displayed the slowest one.

  7. Conceptualizing the Autism Spectrum in Terms of Natural Selection and Behavioral Ecology: The Solitary Forager Hypothesis

    Directory of Open Access Journals (Sweden)

    Jared Edward Reser


    Full Text Available This article reviews etiological and comparative evidence supporting the hypothesis that some genes associated with the autism spectrum were naturally selected and represent the adaptive benefits of being cognitively suited for solitary foraging. People on the autism spectrum are conceptualized here as ecologically competent individuals that could have been adept at learning and implementing hunting and gathering skills in the ancestral environment. Upon independence from their mothers, individuals on the autism spectrum may have been psychologically predisposed toward a different life-history strategy, common among mammals and even some primates, to hunt and gather primarily on their own. Many of the behavioral and cognitive tendencies that autistic individuals exhibit are viewed here as adaptations that would have complemented a solitary lifestyle. For example, the obsessive, repetitive and systemizing tendencies in autism, which can be mistakenly applied toward activities such as block stacking today, may have been focused by hunger and thirst toward successful food procurement in the ancestral past. Both solitary mammals and autistic individuals are low on measures of gregariousness, socialization, direct gazing, eye contact, facial expression, facial recognition, emotional engagement, affiliative need and other social behaviors. The evolution of the neurological tendencies in solitary species that predispose them toward being introverted and reclusive may hold important clues for the evolution of the autism spectrum and the natural selection of autism genes. Solitary animals are thought to eschew unnecessary social contact as part of a foraging strategy often due to scarcity and wide dispersal of food in their native environments. It is thought that the human ancestral environment was often nutritionally sparse as well, and this may have driven human parties to periodically disband. Inconsistencies in group size must have led to

  8. Diagnostic thresholds for quantitative REM sleep phasic burst duration, phasic and tonic muscle activity, and REM atonia index in REM sleep behavior disorder with and without comorbid obstructive sleep apnea. (United States)

    McCarter, Stuart J; St Louis, Erik K; Duwell, Ethan J; Timm, Paul C; Sandness, David J; Boeve, Bradley F; Silber, Michael H


    We aimed to determine whether phasic burst duration and conventional REM sleep without atonia (RSWA) methods could accurately diagnose REM sleep behavior disorder (RBD) patients with comorbid OSA. We visually analyzed RSWA phasic burst durations, phasic, "any," and tonic muscle activity by 3-s mini-epochs, phasic activity by 30-s (AASM rules) epochs, and conducted automated REM atonia index (RAI) analysis. Group RSWA metrics were analyzed and regression models fit, with receiver operating characteristic (ROC) curves determining the best diagnostic cutoff thresholds for RBD. Both split-night and full-night polysomnographic studies were analyzed. N/A. Parkinson disease (PD)-RBD (n = 20) and matched controls with (n = 20) and without (n = 20) OSA. N/A. All mean RSWA phasic burst durations and muscle activities were higher in PD-RBD patients than controls (P sleep without atonia diagnostic thresholds applicable in Parkinson disease-REM sleep behavior disorder (PD-RBD) patient populations with comorbid OSA that may be useful toward distinguishing PD-RBD in typical outpatient populations. © 2014 Associated Professional Sleep Societies, LLC.

  9. Resistive Threshold Logic


    James, A. P.; Francis, L. R. V. J.; Kumar, D.


    We report a resistance based threshold logic family useful for mimicking brain like large variable logic functions in VLSI. A universal Boolean logic cell based on an analog resistive divider and threshold logic circuit is presented. The resistive divider is implemented using memristors and provides output voltage as a summation of weighted product of input voltages. The output of resistive divider is converted into a binary value by a threshold operation implemented by CMOS inverter and/or O...

  10. Methods for automated identification of informative behaviors in natural bioptic driving. (United States)

    Luo, Gang; Peli, Eli


    Visually impaired people may legally drive if wearing bioptic telescopes in some developed countries. To address the controversial safety issue of the practice, we have developed a low-cost in-car recording system that can be installed in study participants' own vehicles to record their daily driving activities. We also developed a set of automated identification techniques of informative behaviors to facilitate efficient manual review of important segments submerged in the vast amount of uncontrolled data. Here, we present the methods and quantitative results of the detection performance for six types of driving maneuvers and behaviors that are important for bioptic driving: bioptic telescope use, turns, curves, intersections, weaving, and rapid stops. The testing data were collected from one normally sighted and two visually impaired subjects across multiple days. The detection rates ranged from 82% up to 100%, and the false discovery rates ranged from 0% to 13%. In addition, two human observers were able to interpret about 80% of targets viewed through the telescope. These results indicate that with appropriate data processing the low-cost system is able to provide reliable data for natural bioptic driving studies.

  11. Crystal chemistry and temperature behavior of the natural hydrous borate colemanite, a mineral commodity of boron (United States)

    Lotti, Paolo; Gatta, G. Diego; Demitri, Nicola; Guastella, Giorgio; Rizzato, Silvia; Ortenzi, Marco Aldo; Magrini, Fabrizio; Comboni, Davide; Guastoni, Alessandro; Fernandez-Diaz, Maria Teresa


    Colemanite, CaB3O4(OH)3ṡH2O, is the most common hydrous Ca-borate, as well as a major mineral commodity of boron. In this study, we report a thorough chemical analysis and the low-temperature behavior of a natural sample of colemanite by means of a multi-methodological approach. From the chemical point of view, the investigated sample resulted to be relatively pure, its composition being very close to the ideal one, with only a minor substitution of Sr2+ for Ca2+. At about 270.5 K, a displacive phase transition from the centrosymmetric P21/a to the acentric P21 space group occurs. On the basis of in situ single-crystal synchrotron X-ray (down to 104 K) and neutron diffraction (at 20 K) data, the hydrogen-bonding configuration of both the polymorphs and the structural modifications at the atomic scale at varying temperatures are described. The asymmetric distribution of ionic charges along the [010] axis, allowed by the loss of the inversion center, is likely responsible for the reported ferroelectric behavior of colemanite below the phase transition temperature.

  12. Computational Intelligence-Assisted Understanding of Nature-Inspired Superhydrophobic Behavior. (United States)

    Zhang, Xia; Ding, Bei; Cheng, Ran; Dixon, Sebastian C; Lu, Yao


    In recent years, state-of-the-art computational modeling of physical and chemical systems has shown itself to be an invaluable resource in the prediction of the properties and behavior of functional materials. However, construction of a useful computational model for novel systems in both academic and industrial contexts often requires a great depth of physicochemical theory and/or a wealth of empirical data, and a shortage in the availability of either frustrates the modeling process. In this work, computational intelligence is instead used, including artificial neural networks and evolutionary computation, to enhance our understanding of nature-inspired superhydrophobic behavior. The relationships between experimental parameters (water droplet volume, weight percentage of nanoparticles used in the synthesis of the polymer composite, and distance separating the superhydrophobic surface and the pendant water droplet in adhesive force measurements) and multiple objectives (water droplet contact angle, sliding angle, and adhesive force) are built and weighted. The obtained optimal parameters are consistent with the experimental observations. This new approach to materials modeling has great potential to be applied more generally to aid design, fabrication, and optimization for myriad functional materials.

  13. Threshold Signature Schemes Application

    Directory of Open Access Journals (Sweden)

    Anastasiya Victorovna Beresneva


    Full Text Available This work is devoted to an investigation of threshold signature schemes. The systematization of the threshold signature schemes was done, cryptographic constructions based on interpolation Lagrange polynomial, elliptic curves and bilinear pairings were examined. Different methods of generation and verification of threshold signatures were explored, the availability of practical usage of threshold schemes in mobile agents, Internet banking and e-currency was shown. The topics of further investigation were given and it could reduce a level of counterfeit electronic documents signed by a group of users.

  14. Natural activation of caspase-3 is required for the development of operant behavior in postnatal ontogenesis. (United States)

    Kudryashova, I V; Stepanichev, M Yu; Gulyaeva, N V


    We have previously demonstrated transient increases in caspase-3 activity in the hippocampus of rat pups from age 17 days. We report here our studies on the effects of inhibition of caspase-3 during this period on the acquisition of a two-way avoidance reaction. Rat pups received intracerebroventricular doses of the caspase-3 inhibitor Z-DEVD-FMK On postnatal day 18. Control animals of the same age received the inactive peptide Z-FA-FMK or isotonic saline solution. Inhibition of caspase-3 during the period of its natural activation in the hippocampus during early ontogenesis was found to impair the development of operant behavior in rats. This was apparent as a reduction in the efficiency of learning during acquisition of active avoidance reactions and decreases in the numbers of intersignal reactions. Administration of the inhibitor had no specific action on the types of conditioned reflex activity less associated with operant learning. Thus, there were no differences between the experimental and control groups in the numbers of emotional reactions to the conditioned stimulus. The number of orientational-investigative conditioned reactions also showed no change after administration of Z-DEVD-FMK. On the background of the reduction in the efficiency of the acquisition of the conditioned active avoidance reflex, the number of incomplete acts, in contrast to other types of conditioned reactions, increased significantly after administration of Z-DEVD-FMK, which is evidence for the persistence of the ability to form associative connections between activation of the conditioned signal and the need to move to the other sector. The difficulty in these animals arose at the decision-taking stage on choosing the appropriate form of behavior. Changes in orientational-investigative behavior were not associated with inhibition of caspase-3 during the critical period of development, as the effects of Z-DEVD-FMK and Z-FA-FMK were similar.

  15. Wear Behavior of Ceramic CAD/CAM Crowns and Natural Antagonists

    Directory of Open Access Journals (Sweden)

    Ella A. Naumova


    Full Text Available Objective: Evaluation of wear behavior of computer-aided design/computer-aided manufacturing (CAD/CAM crowns from various restorative materials and natural antagonists. Method: Full CAD/CAM crowns fabricated with nanoceramic resin (Lava Ultimate (LU, a glass ceramic in a resin interpenetrating matrix (Vita Enamic (VE and a lithium silicate reinforced ceramic enriched with zirconia (Vita Suprinity (VS were cemented on human molars. The crown and antagonists were subjected to simulated chewing. 3D data sets, before and after the chewing simulation, were generated and matched. Occlusal surface roughness, vertical and volume loss of the crowns and antagonists were analyzed. Results: Crown roughness was significantly different between the LU and VE groups after chewing simulation. Crown vertical loss differed in all groups. The highest crown volume loss was found in the LU group, and the lowest in the VE group. Comparisons between the LU and VE groups and the LU and VS groups were significantly different. The highest antagonist volume loss was reached in the VE group, the lowest was in the LU group. Conclusion: Roughness increased after chewing simulation. LU crowns are the most natural antagonist-friendly; these were the most susceptible to vertical and volume loss. Of the tested materials, the VE crowns are the most stable regarding occlusion.

  16. Natural analogue study of long-term leaching behavior of vitrification glass

    International Nuclear Information System (INIS)

    Arai, Takashi; Yusa, Yasuhisa; Kamei; Gento


    In the research on the formation disposal of high level radioactive wastes, the evaluation of the leaching behavior of vitrification glass over ultralong term is one of the important themes. Therefore, the research on the phenomena of quality change in natural environment of volcanic glass, of which the chemical composition resembles well, was carried out (natural analogue study). Among the pyroclastic fall deposit in Fuji and Izu Oshima Volcanoes, the examples of the weathering change of quality of basaltic glass over several hundreds-several thousands years were selected, and on the spot survey, the analysis of groundwater, SEM observation, EPMA and so on were carried out. As the results, the following facts were found. According to the review of the literatures on ancient climate, the atmospheric temperature and precipitation in the past 3000 years were regarded as nearly the same as now. The products from the quality change were similar to the case of laboratory leaching experiment on vitrification glass. The measured ion concentration in groundwater agreed with the calculated values. (K.I.)

  17. Threshold enhancement of diphoton resonances

    Directory of Open Access Journals (Sweden)

    Aoife Bharucha


    Full Text Available We revisit a mechanism to enhance the decay width of (pseudo-scalar resonances to photon pairs when the process is mediated by loops of charged fermions produced near threshold. Motivated by the recent LHC data, indicating the presence of an excess in the diphoton spectrum at approximately 750 GeV, we illustrate this threshold enhancement mechanism in the case of a 750 GeV pseudoscalar boson A with a two-photon decay mediated by a charged and uncolored fermion having a mass at the 12MA threshold and a small decay width, <1 MeV. The implications of such a threshold enhancement are discussed in two explicit scenarios: i the Minimal Supersymmetric Standard Model in which the A state is produced via the top quark mediated gluon fusion process and decays into photons predominantly through loops of charginos with masses close to 12MA and ii a two Higgs doublet model in which A is again produced by gluon fusion but decays into photons through loops of vector-like charged heavy leptons. In both these scenarios, while the mass of the charged fermion has to be adjusted to be extremely close to half of the A resonance mass, the small total widths are naturally obtained if only suppressed three-body decay channels occur. Finally, the implications of some of these scenarios for dark matter are discussed.

  18. The Effects of In-Nature and Virtual-Nature Field Trip Experiences On Proenvironmental Attitudes and Behaviors, And Environmental Knowledge Of Middle School Students (United States)

    Ferderbar, Catherine A.

    To develop sustainable solutions to remediate the complex ecological problems of earth's soil, water, and air degradation requires the talents and skills of knowledgeable, motivated people (UNESCO, 1977; UNESCO, 2010). Researchers historically emphasized that time spent in outdoor, nature activities (Wells & Lekies, 2006), particularly with an adult mentor (Chawla & Cushing, 2007), promotes environmental knowledge and nature-relatedness, precursors to environmental literacy. Research has also demonstrated that technology is integral to the lives of youth, who spend 7:38 hours daily (Rideout, et al., 2010), engaged in electronics. Educators would benefit from knowing if in-nature and virtual-nature field trip experiences provide comparable levels of knowledge and connectedness, to nurture student proenvironmentalism. To investigate field trip phenomena, the researcher studied the impact of virtual-nature and in-nature experiences during which students analyzed water quality along Midwestern rivers. The quasi-experimental, mixed method convergent parallel design with a purposeful sample (n=131) of middle school students from two Midwestern K-8 schools, utilized scientist participant observer field records and narrative response, written assessment aligned to field trip content to evaluate knowledge acquisition. To gain insight into student environmental dispositions, participant observers recorded student comments and behaviors throughout field trips. A survey, administered Pre-Treatment, Post-Treatment 1 and Post-Treatment 2, focused on family water-related behaviors and student perceptions of the need for local government water protection. The findings demonstrated both field trips increased content knowledge significantly, with large effect size. Content knowledge gain from one experience transferred to and was augmented by the second experience. Skill gain (technical and observational) varied by type of field trip and did not transfer. Technical skill was often

  19. The enrichment behavior of natural radionuclides in pulverized oil shale-fired power plants

    International Nuclear Information System (INIS)

    Vaasma, Taavi; Kiisk, Madis; Meriste, Tõnis; Tkaczyk, Alan Henry


    The oil shale industry is the largest producer of NORM (Naturally Occurring Radioactive Material) waste in Estonia. Approximately 11–12 million tons of oil shale containing various amounts of natural radionuclides is burned annually in the Narva oil shale-fired power plants, which accounts for approximately 90% of Estonian electricity production. The radionuclide behavior characteristics change during the fuel combustion process, which redistributes the radionuclides between different ash fractions. Out of 24 operational boilers in the power plants, four use circulating fluidized bed (CFB) technology and twenty use pulverized fuel (PF) technology. Over the past decade, the PF boilers have been renovated, with the main objective to increase the efficiency of the filter systems. Between 2009 and 2012, electrostatic precipitators (ESP) in four PF energy blocks were replaced with novel integrated desulphurization technology (NID) for the efficient removal of fly ash and SO 2 from flue gases. Using gamma spectrometry, activity concentrations and enrichment factors for the 238 U ( 238 U, 226 Ra, 210 Pb) and 232 Th ( 232 Th, 228 Ra) family radionuclides as well as 40 K were measured and analyzed in different PF boiler ash fractions. The radionuclide activity concentrations in the ash samples increased from the furnace toward the back end of the flue gas duct. The highest values in different PF boiler ash fractions were in the last field of the ESP and in the NID ash, where radionuclide enrichment factors were up to 4.2 and 3.3, respectively. The acquired and analyzed data on radionuclide activity concentrations in different PF boiler ashes (operating with an ESP and a NID system) compared to CFB boiler ashes provides an indication that changes in the fuel (oil shale) composition and boiler working parameters, as well as technological enhancements in Estonian oil shale fired power plants, have had a combined effect on the distribution patterns of natural radionuclides in

  20. Natural gas in the Asian Pacific region: market behavior and the Japanese electricity market

    International Nuclear Information System (INIS)

    Jonsson, Bo


    This dissertation consists of four main chapters, all related to the Asian Pacific natural gas market, and the role of the Japanese electricity sector. The natural gas market in Asia Pacific is heavily dependent on the demand from Japan, which imports around 75% of the gas traded as LNG (liquefied natural gas) in the region. The demand for natural gas in Japan is, in turn, almost exclusively driven by the electricity industry that consumes around 70 % of the imported natural gas. On the supply side we find seller concentrations with only six countries exporting LNG in the region. The first main chapter analyzes the market structure of the Asian Pacific natural gas market, the next two relate to the usage of natural gas in the Japanese fossil-fueled electricity production, and the final study investigates the demand for electricity in the residential sector in Japan. The first chapter argues that the buyers in Japan, through cooperation, have the potential to exert the market power that their large market share provides them with. This could be offset by the monopoly power that the six present sellers have. In the chapter four, the solutions for the four imperfect competition cases of, monoposony, monopoly, bilateral monopoly, and the Cournot model are simulated. Neither of the model solutions comes close to both the actual market price, and the actual gas volumes. The model that best mimics the actual price is the bilateral monopoly model, while the monoposony model comes closest to the actual volumes. Giving some mixed evidence of how the Asian LNG market works. Given the indication of market power, the second study analyzes the fossil-fuel mix efficiency in the power sector in Japan. If the power sector is able to exert the alleged market power, it may be the case that they minimize costs according to shadow prices instead of actual market prices. Such behavior could cause the fossil-fuel mix used for power generation to be inefficient. The analysis is based on a

  1. Age-related changes in visual exploratory behavior in a natural scene setting. (United States)

    Hamel, Johanna; De Beukelaer, Sophie; Kraft, Antje; Ohl, Sven; Audebert, Heinrich J; Brandt, Stephan A


    Diverse cognitive functions decline with increasing age, including the ability to process central and peripheral visual information in a laboratory testing situation (useful visual field of view). To investigate whether and how this influences activities of daily life, we studied age-related changes in visual exploratory behavior in a natural scene setting: a driving simulator paradigm of variable complexity was tested in subjects of varying ages with simultaneous eye- and head-movement recordings via a head-mounted camera. Detection and reaction times were also measured by visual fixation and manual reaction. We considered video computer game experience as a possible influence on performance. Data of 73 participants of varying ages were analyzed, driving two different courses. We analyzed the influence of route difficulty level, age, and eccentricity of test stimuli on oculomotor and driving behavior parameters. No significant age effects were found regarding saccadic parameters. In the older subjects head-movements increasingly contributed to gaze amplitude. More demanding courses and more peripheral stimuli locations induced longer reaction times in all age groups. Deterioration of the functionally useful visual field of view with increasing age was not suggested in our study group. However, video game-experienced subjects revealed larger saccade amplitudes and a broader distribution of fixations on the screen. They reacted faster to peripheral objects suggesting the notion of a general detection task rather than perceiving driving as a central task. As the video game-experienced population consisted of younger subjects, our study indicates that effects due to video game experience can easily be misinterpreted as age effects if not accounted for. We therefore view it as essential to consider video game experience in all testing methods using virtual media.

  2. Age-related changes in visual exploratory behavior in a natural scene setting

    Directory of Open Access Journals (Sweden)

    Johanna eHamel


    Full Text Available Diverse cognitive functions decline with increasing age, including the ability to process central and peripheral visual information in a laboratory testing situation (useful visual field of view. To investigate whether and how this influences activities of daily life, we studied age-related changes in visual exploratory behavior in a natural scene setting: a driving simulator paradigm of variable complexity was tested in subjects of varying ages with simultaneous eye- and head-movement recordings via a head-mounted camera. Detection and reaction times were also measured by visual fixation and manual reaction. We considered video computer game experience as a possible influence on performance. Data of 73 participants of varying ages were analyzed, driving two different courses. We analyzed the influence of route difficulty level, age and eccentricity of test stimuli on oculomotor and driving behavior parameters. No significant age effects were found regarding saccadic parameters. In the older subjects head-movements increasingly contributed to gaze amplitude. More demanding courses and more peripheral stimuli locations, induced longer reaction times in all age groups. Deterioration of the functionally useful visual field of view with increasing age was not suggested in our study group. However, video game-experienced subjects revealed larger saccade amplitudes and a broader distribution of fixations on the screen. They reacted faster to peripheral objects suggesting the notion of a general detection task rather than perceiving driving as a central task. As the video game experienced population consisted of younger subjects, our study indicates that effects due to video game experience can easily be misinterpreted as age effects if not accounted for. We therefore view it as essential to consider video game experience in all testing methods using virtual media.

  3. Behavioral Response of Aedes aegypti (Diptera: Culicidae) Larvae to Synthetic and Natural Attractants and Repellents. (United States)

    Gonzalez, Paula V; González Audino, Paola A; Masuh, Héctor M


    Aedes aegypti (L.) (Diptera: Culicidae) is the key vector of three important arboviral diseases: dengue, yellow fever, and chikungunya. Immature stages of this species inhabit human-made containers placed in residential landscapes. In this study, we evaluated a few compounds in a sensitive behavioral assay with Ae. aegypti larvae. The orientation of larvae to different compounds was surveyed using a performance index (PI). The PI represents the response to each odorant, where a value of +1 is indicative of full attraction and -1 represents complete repulsion. The widely used insect repellent N, N-diethyl-m-toluamide elicited a significantly negative PI, as did acetophenone and indole. A yeast extract, a known food source, elicited a significantly positive PI, as did 2-methylphenol, 1-octen-3-ol, 3-methylphenol, and fish food. On the other hand, no response was observed for the essential oil of Eucalyptus grandis x Eucalyptus camaldulensis at the concentration evaluated. Pretreatment of larvae with N-ethylmaleimide and ablation of the antennae resulted in a suppression of behavioral responses. The overall mobility of ablated larvae was indistinguishable from unablated controls, and absence of any visible locomotor dysfunction was observed. This work is a contribution to the study of the chemical ecology of disease vectors with the aim of developing more efficient tools for surveillance and control.Natural and synthetic compounds attractive to Ae. aegypti larvae should be incorporated into integrated pest management programs through the use of baited traps or by improving the efficacy of larvicides commonly used in control campaigns. © The Authors 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email:

  4. Threshold concepts in prosthetics. (United States)

    Hill, Sophie


    Curriculum documents identify key concepts within learning prosthetics. Threshold concepts provide an alternative way of viewing the curriculum, focussing on the ways of thinking and practicing within prosthetics. Threshold concepts can be described as an opening to a different way of viewing a concept. This article forms part of a larger study exploring what students and staff experience as difficult in learning about prosthetics. To explore possible threshold concepts within prosthetics. Qualitative, interpretative phenomenological analysis. Data from 18 students and 8 staff at two universities with undergraduate prosthetics and orthotics programmes were generated through interviews and questionnaires. The data were analysed using an interpretative phenomenological analysis approach. Three possible threshold concepts arose from the data: 'how we walk', 'learning to talk' and 'considering the person'. Three potential threshold concepts in prosthetics are suggested with possible implications for prosthetics education. These possible threshold concepts involve changes in both conceptual and ontological knowledge, integrating into the persona of the individual. This integration occurs through the development of memories associated with procedural concepts that combine with disciplinary concepts. Considering the prosthetics curriculum through the lens of threshold concepts enables a focus on how students learn to become prosthetists. Clinical relevance This study provides new insights into how prosthetists learn. This has implications for curriculum design in prosthetics education.

  5. 40 CFR 68.115 - Threshold determination. (United States)


    ... in accordance with the definition of flammability hazard rating 4 in the NFPA 704, Standard System... more than a threshold quantity is present at a stationary source. (iii) Naturally occurring hydrocarbon..., regulated substances in naturally occurring hydrocarbon mixtures need not be considered when determining...

  6. An electrophysiological and behavioral study of sleep in emperor penguins under natural ambient conditions. (United States)

    Buchet, C; Dewasmes, G; Le Maho, Y


    In two pairs of emperor penguins surgically implanted for chronic recordings of EEG, EOG and EMG, four arousal stages were characterized on the basis of behavioral and electrophysiological criteria: wakefulness (W), drowsiness (D), slow-wave sleep (SWS) and paradoxical sleep (PS). The general patterns of electrographic correlates observed for each arousal stage resemble those reported in other birds. Sleep patterns were examined with these two pairs placed under natural ambient conditions of light and air temperature, the first pair being exposed to moderate cold under alternate conditions of day and night, and the second studied when daylight was total at thermoneutrality. The time spent in sleep (TST) by each group was 41.3% and 45.1% of the 24 hr period respectively, the difference not being significant. As in other birds, PS occurred in very brief episodes lasting, on average, 8 to 10 seconds and occupying only 5 to 6% of the 24 hr period. Whatever the external conditions, the PS to TST ratio appeared to remain unchanged (12 to 14%). Its relatively high value is discussed in relation to predation susceptibility.

  7. Time Preferences and Natural Resource Extraction Behavior: An Experimental Study from Artisanal Fisheries in Zanzibar. (United States)

    Javaid, Aneeque; Kulesz, Micaela M; Schlüter, Achim; Ghosh, Alexandra; Jiddawi, Narriman S


    Natural resource users face a trade-off between present and future consumption. Using harmful methods or extracting unsustainably, lowers future consumption. Therefore, it is reasonable to posit that people with higher time preferences extract more as compared to people with lower time preferences. The present study combines experimental methods and questionnaire data in order to understand the relationship between individual time preferences and fishers' extraction behavior. We elicit individual time preferences using an incentivized experiment, linking the resulting time preference measures to extraction data from a questionnaire, as well as data collected from a framed Common Pool Resource (CPR) experiment. Both the experiments and questionnaire were conducted with artisanal fishers in Zanzibar. Our findings suggest that the relationship between time preferences and CPR extraction is not as straightforward as predicted by classical economic theory. In contrast to earlier studies, we find that fishers' time preferences are negatively correlated to their extraction rates. Our surprising findings can partly be explained by the fact that higher time preferences are associated with lower investment in extraction capability (the disinvestment effect of time preferences), and by fishers´ cognitive abilities.

  8. Aqueous-phase behavior of natural glycolipid biosurfactant mannosylerythritol lipid A: sponge, cubic, and lamellar phases. (United States)

    Imura, Tomohiro; Hikosaka, Yusuke; Worakitkanchanakul, Wannasiri; Sakai, Hideki; Abe, Masahiko; Konishi, Masaaki; Minamikawa, Hiroyuki; Kitamoto, Dai


    The aqueous-phase behavior of mannosylerythritol lipid A (MEL-A), which is a glycolipid biosurfactant produced from vegetable oils by yeast strains of the genus Pseudozyma, was investigated using polarized optical microscopy, small-angle X-ray scattering (SAXS), and differential scanning calorimetry (DSC). MEL-A was found to self-assemble into a variety of distinctive lyotropic liquid crystals including sponge (L3), bicontinuous cubic (V2), and lamella (Lalpha) phases. On the basis of SAXS measurements, we determined the structure of the liquid crystals. The estimated lattice constant for Lalpha was 3.58 nm. DSC measurement revealed that the phase transition enthalpies from the liquid crystal to the fluid isotropic phase were in the range of 0.22-0.44 kJ/mol. Although the present MEL-A phase diagram closely resembled that obtained from relatively hydrophobic poly(oxyethylene) or fluorinated surfactants, the MEL-A L3 region was spread considerably over a wide temperature range (20-65 degrees C) compared to L3 of those surfactants: this is probably due to the unique structure which is molecularly engineered by microorganisms. In this paper, we clarify the aqueous phase diagram of the natural glycolipid biosurfactant MEL-A, and we suggest that the obtained lyotropic crystals are potentially useful as novel nanostructured biomaterials.

  9. Desorption behaviors of BDE-28 and BDE-47 from natural soils with different organic carbon contents. (United States)

    Liu, WenXin; Cheng, FangFang; Li, WeiBo; Xing, BaoShan; Tao, Shu


    Desorption kinetic and isothermal characteristics of BDE-28 and BDE-47 were investigated using natural soils with different organic carbon fractions. The results indicated that a two-compartment first-order model with dominant contribution of slow desorption could adequately describe the released kinetics of studied PBDEs. Desorption isotherms of different samples could be fitted well by linear distribution model or nonlinear Freundlich model. Moreover, most desorption procedures roughly exhibited hysteresis with respect to preceding sorption ones. At the statistically significant level of 0.05 or 0.1, total organic carbon content (f(OC)) exhibited significant correlations with the fitted parameters by the isothermal models. The correlations of f(OC) and SOM fractions (e.g., fulvic acid and humin) with the single point desorption coefficients at lower aqueous concentrations of studied PBDEs were significant; while at higher aqueous concentrations, the relationships were less significant or insignificant. Our findings may facilitate a comprehensive understanding on behaviors of PBDEs in soil systems. Copyright © 2012 Elsevier Ltd. All rights reserved.

  10. Time Preferences and Natural Resource Extraction Behavior: An Experimental Study from Artisanal Fisheries in Zanzibar (United States)

    Kulesz, Micaela M.; Schlüter, Achim; Ghosh, Alexandra; Jiddawi, Narriman S.


    Natural resource users face a trade-off between present and future consumption. Using harmful methods or extracting unsustainably, lowers future consumption. Therefore, it is reasonable to posit that people with higher time preferences extract more as compared to people with lower time preferences. The present study combines experimental methods and questionnaire data in order to understand the relationship between individual time preferences and fishers’ extraction behavior. We elicit individual time preferences using an incentivized experiment, linking the resulting time preference measures to extraction data from a questionnaire, as well as data collected from a framed Common Pool Resource (CPR) experiment. Both the experiments and questionnaire were conducted with artisanal fishers in Zanzibar. Our findings suggest that the relationship between time preferences and CPR extraction is not as straightforward as predicted by classical economic theory. In contrast to earlier studies, we find that fishers’ time preferences are negatively correlated to their extraction rates. Our surprising findings can partly be explained by the fact that higher time preferences are associated with lower investment in extraction capability (the disinvestment effect of time preferences), and by fishers´ cognitive abilities. PMID:28033328

  11. How the expanded crowd-funding mechanism of some southern rural areas in China affects cooperative behaviors in threshold public goods game

    International Nuclear Information System (INIS)

    Chen, Qiao; Chen, Tong; Wang, Yongjie


    Highlights: • The influence of emotions on the public goods game can not be ignored. • Individuals’ emotions will be influenced by list and lobbyists’ words when making decisions. • Unless the synergy factor is larger than a certain value, it is necessary to encourage more people to act as lobbyists. • Whether and how to publish the list depend on the situation. - Abstract: The pursuit of high cooperation rates in public goods games has attracted many researchers. However, few researchers attach much weight to the influence of emotions on decision-making, especially on public goods games. From ancient to modern times, publishing the list of cooperators to stimulate cooperation has been a common phenomenon in some southern rural areas in China. Actually, the published list can influence individuals’ behaviors by affecting their emotions. Here we extend the method of publishing the list and optimize it by adding a lobbyist mechanism. Through numerical simulations, we find that the role of lobbyists can not be ignored unless the synergy factor is larger than a certain value. Additionally, we find that publishing the list certainly has a great effect on individual’s cooperative behavior. But whether to publish the list or not and how to publish the list depend on the situation.

  12. Regional Seismic Threshold Monitoring

    National Research Council Canada - National Science Library

    Kvaerna, Tormod


    ... model to be used for predicting the travel times of regional phases. We have applied these attenuation relations to develop and assess a regional threshold monitoring scheme for selected subregions of the European Arctic...

  13. Tourists’ Environmentally Responsible Behavior in Response to Climate Change and Tourist Experiences in Nature-Based Tourism

    Directory of Open Access Journals (Sweden)

    Ju Hyoung Han


    Full Text Available Nature-based tourism destinations—locations in which economic viability and environmental responsibility are sought—are sensitive to climate change and its effects on important environmental components of the tourism areas. To meet the dual roles, it is important for destination marketers and resources managers to provide quality experiences for tourists and to induce tourists’ environmentally responsible behavior in such destinations. This study documents the importance of perceptions toward climate change and tourist experiences in determining tourists’ environmentally responsible behavior while enjoying holidays at nature-based tourism destinations in Jeju Island, South Korea. Two hundred and eleven Korean and 204 Chinese tourists marked dominant tourist arrivals to the island, and responded to the survey questionnaire. Results showed that perceptions toward climate change and tourist experiences affect Korean tourists’ environmentally responsible behavior intentions, whereas tourist experiences—not perceptions toward climate change—only significantly affect Chinese tourists’ behavior intention. In a nature-based tourism context under the pressure of climate change and adverse environmental effects as consequences of tourism activities, resources managers and destination marketers need to develop environmental campaigns or informative tourist programs to formulate environmentally responsible behavior as well as to increase tourist quality experiences among domestic and international tourists.

  14. natural

    Directory of Open Access Journals (Sweden)

    Elías Gómez Macías


    Full Text Available Partiendo de óxido de magnesio comercial se preparó una suspensión acuosa, la cual se secó y calcinó para conferirle estabilidad térmica. El material, tanto fresco como usado, se caracterizó mediante DRX, área superficial BET y SEM-EPMA. El catalizador mostró una matriz de MgO tipo periclasa con CaO en la superficie. Las pruebas de actividad catalítica se efectuaron en lecho fijo empacado con partículas obtenidas mediante prensado, trituración y clasificación del material. El flujo de reactivos consistió en mezclas gas natural-aire por debajo del límite inferior de inflamabilidad. Para diferentes flujos y temperaturas de entrada de la mezcla reactiva, se midieron las concentraciones de CH4, CO2 y CO en los gases de combustión con un analizador de gases tipo infrarrojo no dispersivo (NDIR. Para alcanzar conversión total de metano se requirió aumentar la temperatura de entrada al lecho a medida que se incrementó el flujo de gases reaccionantes. Los resultados obtenidos permiten desarrollar un sistema de combustión catalítica de bajo costo con un material térmicamente estable, que promueva la alta eficiencia en la combustión de gas natural y elimine los problemas de estabilidad, seguridad y de impacto ambiental negativo inherentes a los procesos de combustión térmica convencional.

  15. Roots at the Percolation Threshold (United States)

    Kroener, E.; Ahmed, M. A.; Kaestner, A.; Vontobel, P.; Zarebanadkouki, M.; Carminati, A.


    Much of the carbon assimilated by plants during photosynthesis is lost to the soil via rhizodepositions. One component of rhizopdeposition is mucilage, a hydrogel that dramatically alters the soil physical properties. Mucilage was assumed to explain unexpectedly low rhizosphere rewetting rates during irrigation (Carminati et al. 2010) and temporarily water repellency in the rhizosphere after severe drying (Moradi et al. 2012).Here, we present an experimental and theoretical study for the rewetting behaviour of a soil mixed with mucilage, which was used as an analogue of the rhizosphere. Our samples were made of two layers of untreated soils separated by a thin layer (ca. 1 mm) of soil treated with mucilage. We prepared soil columns of varying particle size, mucilage concentration and height of the middle layer above the water table. The dry soil columns were re-wetted by capillary rise from the bottom.The rewetting of the middle layer showed a distinct dual behavior. For mucilage concentrations lower than a certain threshold, water could cross the thin layer almost immediately after rewetting of bulk soil. At slightly higher mucilage concentrations, the thin layer was almost impermeable. The mucilage concentration at the threshold strongly depended on particle size: the smaller the particle size the larger the soil specific surface and the more mucilage was needed to cover the entire particle surface and to induce water repellency.We applied a classic pore network model to simulate the experimental observations. In the model a certain fraction of nodes were randomly disconnected to reproduce the effect of mucilage in temporarily blocking the flow. The percolation model could qualitatively reproduce well the threshold characteristics of the experiments. Our experiments, together with former observations of water dynamics in the rhizosphere, suggest that the rhizosphere is near the percolation threshold, where small variations in mucilage concentration sensitively

  16. Genetic Architecture of Natural Variation Underlying Adult Foraging Behavior That Is Essential for Survival of Drosophila melanogaster. (United States)

    Lee, Yuh Chwen G; Yang, Qian; Chi, Wanhao; Turkson, Susie A; Du, Wei A; Kemkemer, Claus; Zeng, Zhao-Bang; Long, Manyuan; Zhuang, Xiaoxi


    Foraging behavior is critical for the fitness of individuals. However, the genetic basis of variation in foraging behavior and the evolutionary forces underlying such natural variation have rarely been investigated. We developed a systematic approach to assay the variation in survival rate in a foraging environment for adult flies derived from a wild Drosophila melanogaster population. Despite being such an essential trait, there is substantial variation of foraging behavior among D. melanogaster strains. Importantly, we provided the first evaluation of the potential caveats of using inbred Drosophila strains to perform genome-wide association studies on life-history traits, and concluded that inbreeding depression is unlikely a major contributor for the observed large variation in adult foraging behavior. We found that adult foraging behavior has a strong genetic component and, unlike larval foraging behavior, depends on multiple loci. Identified candidate genes are enriched in those with high expression in adult heads and, demonstrated by expression knock down assay, are involved in maintaining normal functions of the nervous system. Our study not only identified candidate genes for foraging behavior that is relevant to individual fitness, but also shed light on the initial stage underlying the evolution of the behavior. © The Author 2017. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

  17. Aqueous-phase behavior and vesicle formation of natural glycolipid biosurfactant, mannosylerythritol lipid-B. (United States)

    Worakitkanchanakul, Wannasiri; Imura, Tomohiro; Fukuoka, Tokuma; Morita, Tomotake; Sakai, Hideki; Abe, Masahiko; Rujiravanit, Ratana; Chavadej, Sumaeth; Minamikawa, Hiroyuki; Kitamoto, Dai


    Mannosylerythritol lipids (MELs) are one of the most promising glycolipid biosurfactants produced by yeast strains of the genus Pseudozyma. In this study, the aqueous-phase behavior of a new monoacetyl MEL derivative, 1-O-beta-(2',3'-di-O-alka(e)noyl-6'-O-acetyl-d-mannopyranosyl)-d-erythritol (MEL-B), was investigated using polarized optical microscopy, small-angle X-ray scattering (SAXS), confocal laser scanning microscopy (CLSM), and differential scanning calorimetry (DSC). The present MEL-B was found to self-assemble into a lamellar (L(alpha)) phase over remarkably wide concentration and temperature ranges. According to SAXS measurement, the interlayer spacing (d) was estimated to be almost constant (about 4.7 nm) at the low MEL-B concentration (60 wt.%) region, the d-spacing gradually decreased to 3.1 nm with an increase in the MEL-B concentration. The thermal stability of the liquid crystalline phase was investigated by DSC measurement. The obtained L(alpha) phase was found to be stable up to 95 degrees C below a MEL-B concentration of 85 wt.%; then, the melting temperature of the liquid crystalline phase dramatically decreased with an increase in MEL-B concentration (above 85 wt.%). Furthermore, we found relatively large vesicles (1-5 microm) at the low MEL-B concentration using CLSM observation. The trapped volume of the obtained MEL-B vesicle was estimated to be about 0.42 microL/mumol by glucose dialysis method. These results suggest that the natural glycolipid biosurfactant, the newly found MEL-B, would be useful in various fields of applications as an L(alpha) phase- and/or vesicle-forming lipid.

  18. Linking AS, SE, V, and MN Behavior to Natural Biostimulated Uranium Cycling

    Energy Technology Data Exchange (ETDEWEB)

    Keimowitz, Alison [Vassar College, Poughkeepsie, NY (United States); Ranville, James [Colorado School of Mines, Golden, CO (United States); Mailloux, Brian [Barnard College, New York, NY (United States); Figueroa, Linda [Colorado School of Mines, Golden, CO (United States)


    The project “Linking As, Se, V, and Mn behavior to Natural and Biostimulated Uranium Cycling” successfully investigated Arsenic cycling the Rifle Colorado IFRC. This project trained undergraduate and graduate students at the Colorado School of Mines, Vassar College, and Barnard College. This resulted in both undergraduate theses and a PhD thesis and multiple publications. The science was highly successful and we were able to test the main hypotheses. We have shown that (H1) under reducing conditions that promote uranium immobilization arsenic is readily mobilized, that (H2) thioarsenic species are abundant during this mobilization, and (H3) we have examined arsenic mobilization for site sediment. At the Rifle IFRC Acetate was added during experiments to immobilize Uranium. These experiments successfully immobilized uranium but unfortunately would mobilize arsenic. We developed robust sampling and analysis methods for thioarsenic species. We showed that the mobilization occurred under sulfate reducing conditions and the majority of the arsenic was in the form of thioarsenic species. Previous studies had predicted the presence of thioarsenic species but this study used robust field and laboratory methods to quantitatively determine the presence of thioarsenic species. During stimulation in wells with high arsenic the primary species were trithioarsenate and dithioarsenate. In wells with low levels of arsenic release thioarsenates were absent or minor components. Fortunately after the injection of acetate ended the aquifer would become less reducing and the arsenic concentrations would decrease to pre-injection levels. In aquifers where organic carbon is being added as a remedial method or as a contaminant the transient mobility of arsenic during sulfidogenesis should be considered especially in sulfate rich aquifers as this could impact downgradient water quality.

  19. Hydrodynamics of sediment threshold (United States)

    Ali, Sk Zeeshan; Dey, Subhasish


    A novel hydrodynamic model for the threshold of cohesionless sediment particle motion under a steady unidirectional streamflow is presented. The hydrodynamic forces (drag and lift) acting on a solitary sediment particle resting over a closely packed bed formed by the identical sediment particles are the primary motivating forces. The drag force comprises of the form drag and form induced drag. The lift force includes the Saffman lift, Magnus lift, centrifugal lift, and turbulent lift. The points of action of the force system are appropriately obtained, for the first time, from the basics of micro-mechanics. The sediment threshold is envisioned as the rolling mode, which is the plausible mode to initiate a particle motion on the bed. The moment balance of the force system on the solitary particle about the pivoting point of rolling yields the governing equation. The conditions of sediment threshold under the hydraulically smooth, transitional, and rough flow regimes are examined. The effects of velocity fluctuations are addressed by applying the statistical theory of turbulence. This study shows that for a hindrance coefficient of 0.3, the threshold curve (threshold Shields parameter versus shear Reynolds number) has an excellent agreement with the experimental data of uniform sediments. However, most of the experimental data are bounded by the upper and lower limiting threshold curves, corresponding to the hindrance coefficients of 0.2 and 0.4, respectively. The threshold curve of this study is compared with those of previous researchers. The present model also agrees satisfactorily with the experimental data of nonuniform sediments.

  20. Hyper-arousal decreases human visual thresholds.

    Directory of Open Access Journals (Sweden)

    Adam J Woods

    Full Text Available Arousal has long been known to influence behavior and serves as an underlying component of cognition and consciousness. However, the consequences of hyper-arousal for visual perception remain unclear. The present study evaluates the impact of hyper-arousal on two aspects of visual sensitivity: visual stereoacuity and contrast thresholds. Sixty-eight participants participated in two experiments. Thirty-four participants were randomly divided into two groups in each experiment: Arousal Stimulation or Sham Control. The Arousal Stimulation group underwent a 50-second cold pressor stimulation (immersing the foot in 0-2° C water, a technique known to increase arousal. In contrast, the Sham Control group immersed their foot in room temperature water. Stereoacuity thresholds (Experiment 1 and contrast thresholds (Experiment 2 were measured before and after stimulation. The Arousal Stimulation groups demonstrated significantly lower stereoacuity and contrast thresholds following cold pressor stimulation, whereas the Sham Control groups showed no difference in thresholds. These results provide the first evidence that hyper-arousal from sensory stimulation can lower visual thresholds. Hyper-arousal's ability to decrease visual thresholds has important implications for survival, sports, and everyday life.

  1. Hadron production near threshold

    Indian Academy of Sciences (India)

    Final state interaction effects in → + and → 3He reactions are explored near threshold to study the sensitivity of the cross-sections to the potential and the scattering matrix. The final state scattering wave functions between and and and 3He are described rigorously. The production is ...

  2. Elaborating on Threshold Concepts (United States)

    Rountree, Janet; Robins, Anthony; Rountree, Nathan


    We propose an expanded definition of Threshold Concepts (TCs) that requires the successful acquisition and internalisation not only of knowledge, but also its practical elaboration in the domains of applied strategies and mental models. This richer definition allows us to clarify the relationship between TCs and Fundamental Ideas, and to account…

  3. Boundaries, Thresholds, and Consequences. (United States)

    Smith, Carl R.


    Highlights issues in the debate concerning Individuals with Disabilities Education Act (IDEA) special education legislation as it relates to student discipline and incarcerated juveniles. Focuses on assessment issues and thresholds for diagnosable conditions. Looks at debates surrounding IDEA and some of the consequences of new legislation. (RJM)

  4. The Idiographic Study of Leadership Behavior in Natural Settings: An Empirical Analysis Using a Single Case Experimental Design. (United States)


    Management , 1977, 1, 105-109. LAuthans, F. Leadership : A proposal for a social learning theory base and observational and functional analysis...Manz, C.C., & Sims, H.P. Self management as a substitute for leadership : A social learning theory perspective. Academy of Management Review, 1980, 5...AD-AI19 89 NEBRASKA UNIV LINCOLN DEPT OF MANAGEMENT F/G 5/1 THE IDIOGRAPHIC STUDY OF LEADERSHIP BEHAVIOR IN NATURAL SETTING-ETCIU)AUG 82 T R DAVI , F

  5. Tourists’ Environmentally Responsible Behavior in Response to Climate Change and Tourist Experiences in Nature-Based Tourism


    Ju Hyoung Han; Min Jae Lee; Yun-Seop Hwang


    Nature-based tourism destinations—locations in which economic viability and environmental responsibility are sought—are sensitive to climate change and its effects on important environmental components of the tourism areas. To meet the dual roles, it is important for destination marketers and resources managers to provide quality experiences for tourists and to induce tourists’ environmentally responsible behavior in such destinations. This study documents the importance of perceptions toward...

  6. Density and viscosity behavior of a North Sea crude oil, natural gas liquid, and their mixtures

    DEFF Research Database (Denmark)

    Schmidt, KAG; Cisneros, Sergio; Kvamme, B


    to accurately model the saturation pressures, densities, and viscosities of petroleum systems ranging from natural gases to heavy crude oils. The applicability of this overall modeling technique to reproduce measured bubble points, densities, and viscosities of a North Sea crude oil, a natural gas liquid...

  7. Classrooms with nature views: Evidence of differing student perceptions and behaviors (United States)

    J.A. Benfield; G.N. Rainbolt; P.A. Bell; G.H. Donovan


    Viewing peaceful natural environments has been shown to restore cognitive abilities and reduce physiological arousal. As such, visual access to the natural environment is becoming more commonplace in built environments. One exception to that trend is in educational settings where windowless classrooms are used to reduce outside distractions. The current study examines...

  8. How to analytically characterize the epidemic threshold within the coupled disease-behavior systems?. Comment on "Coupled disease-behavior dynamics on complex networks: A review" by Z. Wang et al. (United States)

    Xia, Cheng-Yi; Ding, Shuai; Sun, Shi-Wen; Wang, Li; Gao, Zhong-Ke; Wang, Juan


    As is well known, outbreak of epidemics may drive the human population to take some necessary measures to protect themselves from not being infected by infective ones, these precautions in turn will also keep from the further spreading of infectious diseases among the population. Thus, to fully comprehend the epidemic spreading behavior within real-world systems, the interplay between disease dynamics and human behavioral and social dynamics needs to be considered simultaneously, such that some effective containment-measures can be successfully developed [1-3].

  9. Baseline Behavior of Pilot Whales and their Responses to Playback of Anthropogenic and Natural Sounds (United States)


    1 DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited. Baseline Behavior of Pilot Whales and their Responses to...N000141210417 LONG-TERM GOALS This project investigates the social ecology and baseline behavior of pilot whales , and their responses to anthropogenic...and estimating a robust quantification of group cohesion  Conduct playback experiments to study responses of tagged whales to sounds of killer whales

  10. Systematic review of the efficacy of cognitive-behavior therapy related treatments for victims of natural disasters: a worldwide problem.

    Directory of Open Access Journals (Sweden)

    Alessandra Pereira Lopes

    Full Text Available Natural disasters can have devastating consequences. Each year, about 225 million people are victims of natural disasters worldwide, and up to 13,5 million of these people can develop post-traumatic stress disorder (PTSD in the first or second year following the disaster. Cognitive-behavior therapy (CBT is the first-choice treatment for this disorder. In order to evaluate the efficacy of psychotherapeutic treatment based on cognitive-behavior therapy for people who developed post traumatic stress disorder after natural disasters we conducted a systematic search of published studies. We used the terms reported below in the electronic databases ISI Web of Science, PsycINFO, PubMed, PILOTS and Scopus with no restrictions of language or publication date. Articles that described randomized controlled, non-randomized controlled and non controlled studies on the efficacy of cognitive-behavior therapy for individuals diagnosed with post-traumatic stress disorder after exposure to a natural disaster were eligible for inclusion. The studies were required to use a standardized measure of effectiveness before and after the intervention and have a group of patients who had used cognitive-behavior therapy as the only intervention. Our search identified 820 studies, and 11 were selected for this review. These 11 studies involved 742 subjects, 10 related to earthquakes and 1 to a hurricane. The cognitive-behavior therapy techniques used were various: 7 studies used exposure therapy, 2 studies used problem solving, and the only 2 studies with adolescents used techniques including reconstructions and reprocessing of the traumatic experience. As limitations, the search involved only five electronic databases, no experts in the field were consulted, and the heterogeneity of the findings made it impossible to perform a meta-analysis. The results suggest the efficacy of cognitive-behavior therapy, particularly exposure techniques, for the treatment of post

  11. Systematic review of the efficacy of cognitive-behavior therapy related treatments for victims of natural disasters: a worldwide problem. (United States)

    Lopes, Alessandra Pereira; Macedo, Tânia Fagundes; Coutinho, Evandro Silva Freire; Figueira, Ivan; Ventura, Paula Rui


    Natural disasters can have devastating consequences. Each year, about 225 million people are victims of natural disasters worldwide, and up to 13,5 million of these people can develop post-traumatic stress disorder (PTSD) in the first or second year following the disaster. Cognitive-behavior therapy (CBT) is the first-choice treatment for this disorder. In order to evaluate the efficacy of psychotherapeutic treatment based on cognitive-behavior therapy for people who developed post traumatic stress disorder after natural disasters we conducted a systematic search of published studies. We used the terms reported below in the electronic databases ISI Web of Science, PsycINFO, PubMed, PILOTS and Scopus with no restrictions of language or publication date. Articles that described randomized controlled, non-randomized controlled and non controlled studies on the efficacy of cognitive-behavior therapy for individuals diagnosed with post-traumatic stress disorder after exposure to a natural disaster were eligible for inclusion. The studies were required to use a standardized measure of effectiveness before and after the intervention and have a group of patients who had used cognitive-behavior therapy as the only intervention. Our search identified 820 studies, and 11 were selected for this review. These 11 studies involved 742 subjects, 10 related to earthquakes and 1 to a hurricane. The cognitive-behavior therapy techniques used were various: 7 studies used exposure therapy, 2 studies used problem solving, and the only 2 studies with adolescents used techniques including reconstructions and reprocessing of the traumatic experience. As limitations, the search involved only five electronic databases, no experts in the field were consulted, and the heterogeneity of the findings made it impossible to perform a meta-analysis. The results suggest the efficacy of cognitive-behavior therapy, particularly exposure techniques, for the treatment of post-traumatic stress disorder

  12. Daily patterns of anxiety in anorexia nervosa: associations with eating disorder behaviors in the natural environment. (United States)

    Lavender, Jason M; De Young, Kyle P; Wonderlich, Stephen A; Crosby, Ross D; Engel, Scott G; Mitchell, James E; Crow, Scott J; Peterson, Carol B; Le Grange, Daniel


    The role of anxiety has been emphasized in etiological/maintenance models of anorexia nervosa. This study identified daily patterns of anxiety in anorexia nervosa and examined the likelihood of the occurrence of eating disorder behaviors in each trajectory, the daily temporal distribution of eating disorder behaviors in each trajectory, and the extent to which the tendency to exhibit particular anxiety trajectories was associated with baseline diagnostic and trait-level personality variables. Women with full or subthreshold anorexia nervosa (N = 118) completed a 2-week ecological momentary assessment (EMA) protocol during which they reported on a variety of behavioral and affective variables, including anxiety and eating disorder behaviors. Using latent growth mixture modeling to classify EMA days (N = 1,526) based on anxiety ratings, we identified 7 distinct daily anxiety trajectories. Overall differences between trajectories were found for rates of binge eating, self-induced vomiting, body checking, skipping meals, and dietary restriction. Furthermore, distinct daily temporal distributions of eating disorder behaviors were found across the trajectories, with peaks in the probability of behaviors frequently coinciding with high levels of anxiety. Finally, traits of personality pathology (affective lability, self-harm, social avoidance, and oppositionality) and the presence of a co-occurring mood disorder were found to be associated with the tendency to experience particular daily anxiety trajectories (e.g., stable high anxiety). Findings support the presence of within-person variability in daily anxiety patterns in anorexia nervosa and also provide evidence for an association between these anxiety patterns and eating disorder behaviors. PsycINFO Database Record (c) 2013 APA, all rights reserved.

  13. Crossmodal integration improves sensory detection thresholds in the ferret.

    Directory of Open Access Journals (Sweden)

    Karl J Hollensteiner

    Full Text Available During the last two decades ferrets (Mustela putorius have been established as a highly efficient animal model in different fields in neuroscience. Here we asked whether ferrets integrate sensory information according to the same principles established for other species. Since only few methods and protocols are available for behaving ferrets we developed a head-free, body-restrained approach allowing a standardized stimulation position and the utilization of the ferret's natural response behavior. We established a behavioral paradigm to test audiovisual integration in the ferret. Animals had to detect a brief auditory and/or visual stimulus presented either left or right from their midline. We first determined detection thresholds for auditory amplitude and visual contrast. In a second step, we combined both modalities and compared psychometric fits and the reaction times between all conditions. We employed Maximum Likelihood Estimation (MLE to model bimodal psychometric curves and to investigate whether ferrets integrate modalities in an optimal manner. Furthermore, to test for a redundant signal effect we pooled the reaction times of all animals to calculate a race model. We observed that bimodal detection thresholds were reduced and reaction times were faster in the bimodal compared to unimodal conditions. The race model and MLE modeling showed that ferrets integrate modalities in a statistically optimal fashion. Taken together, the data indicate that principles of multisensory integration previously demonstrated in other species also apply to crossmodal processing in the ferret.

  14. Effect of natural weathering conditions on the dynamic behavior of woven aramid composites (United States)

    Kaya, A. I.; Kısa, M.; Özen, M.


    In this study, aging of woven aramid/epoxy composites under different natural conditions were studied. Composite beams were manufactured by Vacuum Assisted Resin Infusion Method (VARIM). Composites were cut into specimen according to ASTM D3039 and vibration tests. Elastic moduli of reference composites were found according to ASTM D3039 standard. Validation of methodology was performed numerically in Ansys software before aging process. An algorithm, which is predicated on FFT (Fast Fourier Transforms), was composed in Matlab to process output of vibration analysis data so as to identify natural frequencies of beams. Composites were aged for 12 months and various natural weathering aging conditions effects on woven aramid composite beams were surveyed through vibration analysis with 3 months interval. Five specimens of woven aramid beams were considered for dynamic tests and effect of aging on first three natural frequencies were determined.

  15. Hadron production near threshold

    Indian Academy of Sciences (India)

    Abstract. Final state interaction effects in pp → pΛK+ and pd → 3He η reactions are explored near threshold to study the sensitivity of the cross-sections to the pΛ potential and the ηN scattering matrix. The final state scattering wave functions between Λ and p and η and 3He are described rigorously. The Λ production is ...

  16. Deformation Behavior between Hydraulic and Natural Fractures Using Fully Coupled Hydromechanical Model with XFEM

    Directory of Open Access Journals (Sweden)

    Fei Liu


    Full Text Available There has been a growing consensus that preexisting natural fractures play an important role during stimulation. A novel fully coupled hydromechanical model using extended finite element method is proposed. This directly coupled scheme avoids the cumbersome process during calculating the fluid pressure in complicated fracture networks and translating into an equivalent nodal force. Numerical examples are presented to simulate the hydraulic fracture propagation paths for simultaneous multifracture treatments with properly using the stress shadow effects for horizontal wells and to reveal the deformation response and interaction mechanism between hydraulic induced fracture and nonintersected natural fractures at orthotropic and nonorthotropic angles. With the stress shadow effects, the induced hydraulic flexural fracture deflecting to wellbore rather than transverse fracture would be formed during the progress of simultaneous fracturing for a horizontal well. The coupled hydromechanical simulation reveals that the adjacent section to the intersection is opened and the others are closed for orthogonal natural fracture, while the nonorthogonal natural fracture is activated near the intersection firstly and along the whole section with increasing perturbed stresses. The results imply that the induced hydraulic fracture tends to cross orthotropic natural fracture, while it is prior to being arrested by the nonorthotropic natural fracture.

  17. Small-Boat Noise Impacts Natural Settlement Behavior of Coral Reef Fish Larvae. (United States)

    Simpson, Stephen D; Radford, Andrew N; Holles, Sophie; Ferarri, Maud C O; Chivers, Douglas P; McCormick, Mark I; Meekan, Mark G


    After a pelagic larval phase, settlement-stage coral reef fish must locate a suitable reef habitat for juvenile life. Reef noise, produced by resident fish and invertebrates, provides an important cue for orientation and habitat selection during this process, which must often occur in environments impacted by anthropogenic noise. We adapted an established field-based protocol to test whether recorded boat noise influenced the settlement behavior of reef fish. Fewer fish settled to patch reefs broadcasting boat + reef noise compared with reef noise alone. This study suggests that boat noise, now a common feature of many reefs, can compromise critical settlement behavior of reef fishes.

  18. Does "Compulsory Volunteering" Affect Subsequent Behavior? Evidence from a Natural Experiment in Canada (United States)

    Yang, Wei


    This paper estimates the impact of "compulsory volunteerism" for adolescents on subsequent volunteer behavior exploiting the introduction of a mandatory community service program for high school (HS) students in Ontario, Canada. We use difference-in-differences approach with a large longitudinal dataset. Our estimates show that the…

  19. The side benefit of behavior : using keystroke dynamics to inform Natural Language Processing

    NARCIS (Netherlands)

    Plank, Barbara


    When people produce or read texts, they produce loads of by-product in form of behavioral data. Examples include click-through data, but also more distant sources such as cognitive processing data like eye tracking or keystroke dynamics. Such fortuitous data [5] represents a potentially immense

  20. The Nature and Frequency of Cyber Bullying Behaviors and Victimization Experiences in Young Canadian Children (United States)

    Holfeld, Brett; Leadbeater, Bonnie J.


    As access to technology is increasing in children and adolescents, there are growing concerns over the dangers of cyber bullying. It remains unclear what cyber bullying looks like among young Canadian children and how common these experiences are. In this study, we examine the psychometric properties of a measure of cyber bullying behaviors and…

  1. Play in Natural Environments: A Pilot Study Quantifying the Behavior of Children on Playground Equipment (United States)

    Miller, Lucy Jane; Schoen, Sarah A.; Camarata, Stephen M.; McConkey, John; Kanics, Ingrid M.; Valdez, Andrea; Hampton, Shannon


    Playground design is critical to school-based practice, insuring access and use for all children. The play behavior of children with special needs is qualitatively and quantitatively different than their typically developing peers. However, empirical data is needed to support the therapeutic value of playground equipment used with school-aged…

  2. Characterizing resilient behavior of naturally occurring bituminous sands for road construction

    CSIR Research Space (South Africa)

    Anochie-Boateng, Joseph


    Full Text Available large capacity haul trucks and shovels. This paper focuses on determining in laboratory the resilient behavior of three oil sand materials with bitumen contents of 8.5, 13.3, and 14.5% by weight. The resilient modulus MR properties were obtained using a...

  3. Transient behavior of natural circulation for boiling two-phase flow, 2

    International Nuclear Information System (INIS)

    Aritomi, Masanori; Chiang, Jing-Hsien; Mori, Michitugu.


    In this set of experiments, natural circulation in boiling two-phase flow has been investigated for power transients, simulating the start-up process in a natural circulation BWR. This was done in order to understand the underlying mechanism of thermo-hydraulic instability which may appear during a start-up. In this paper, geysering is dealt with especially and the driving mechanism is clarified by investigating the stability related to effects of inlet velocity, subcooling, temperature in an outlet plenum and non-heated length between heated section and the outlet plenum. Furthermore, by considering these results and the operational experience in the Dodewaard reactor, recommendations on how the thermo-hydraulic instabilities can be prevented from occurring are proposed concerning a reactor configuration and start-up procedure for natural circulation BWRs. (author)


    Directory of Open Access Journals (Sweden)

    Josip Arnerić


    Full Text Available The objective of extreme value analysis is to quantify the probabilistic behavior of unusually large losses using only extreme values above some high threshold rather than using all of the data which gives better fit to tail distribution in comparison to traditional methods with assumption of normality. In our case we estimate market risk using daily returns of the CROBEX index at the Zagreb Stock Exchange. Therefore, it’s necessary to define the excess distribution above some threshold, i.e. Generalized Pareto Distribution (GPD is used as much more reliable than the normal distribution due to the fact that gives the accent on the extreme values. Parameters of GPD distribution will be estimated using maximum likelihood method (MLE. The contribution of this paper is to specify threshold which is large enough so that GPD approximation valid but low enough so that a sufficient number of observations are available for a precise fit.

  5. Threshold Theory Tested in an Organizational Setting

    DEFF Research Database (Denmark)

    Christensen, Bo T.; Hartmann, Peter V. W.; Hedegaard Rasmussen, Thomas


    correlations differed significantly. The finding was stable across distinct parts of the sample, providing support for the theory, although the correlations in all subsamples were small. The findings lend support to the existence of threshold effects using perceptual measures of behavior in real......A large sample of leaders (N = 4257) was used to test the link between leader innovativeness and intelligence. The threshold theory of the link between creativity and intelligence assumes that below a certain IQ level (approximately IQ 120), there is some correlation between IQ and creative...... potential, but above this cutoff point, there is no correlation. Support for the threshold theory of creativity was found, in that the correlation between IQ and innovativeness was positive and significant below a cutoff point of IQ 120. Above the cutoff, no significant relation was identified, and the two...

  6. How do type and size of natural environments relate to physical activity behavior?

    NARCIS (Netherlands)

    Jansen, F. M.; Ettema, D. F.; Kamphuis, C. B.M.; Pierik, Frank H.; Dijst, M. J.


    Natural environments (NE) are promoted as places that support physical activity (PA), but evidence on PA distribution across various types and sizes of NE is lacking. Accelerometers and GPS-devices measured PA of Dutch general population adults aged 45–65 years (N=279). Five NE types were

  7. Naturally green: Harnessing stone age psychological biases to foster environmental behavior

    NARCIS (Netherlands)

    van Vugt, M.; Griskevicius, V.; Schultz, P. W.


    It is widely agreed that humans must reduce their environmental impact. We propose that an improved understanding of our evolved human nature can help to improve programs and policies to address environmental problems. Combining evolutionary and social psychological approaches, we argue that

  8. Moderating Factors of Natural Mentoring Relationships, Problem Behaviors, and Emotional Well-Being (United States)

    Whitney, Stephen D.; Hendricker, Elise N.; Offutt, Cheryl A.


    This study examines naturally occurring mentors by the quality and presence of a mentor (no mentor, low quality, high quality), type of mentors (adult mentors vs. peer mentors), and mentor quality within mentor type. A sub-sample of adolescents from the National Longitudinal Study of Adolescent-Health is used. Results indicate the effect of…

  9. Impact of natural organic matter on particle behavior and phototoxicity of titanium dioxide nanoparticles (United States)

    Due to their inherent phototoxicity and inevitable environmental release, titanium dioxide nanoparticles (nano-TiO2) are increasingly studied in the field of aquatic toxicology. One of the particular interests is the interactions between nano-TiO2 and natural organic matter (NOM)...

  10. The nature of the interest construct and its utility in the study of leisure behavior (United States)

    Ellen B. Drogin Rodgers; Brenda P. Wiggins


    The intent of this paper is to initiate discussion regarding the nature of the interest construct. Interest influences "what people attend to, think about, discuss and learn more about" (Frick, 1992) and has been used pervasively in many disciplines as a means of explaining concepts as varied as career choice, motivation, enjoyment, learning and academic...

  11. Use of natural analogues to predict the behavior of transuranic actinide elements in the environment

    International Nuclear Information System (INIS)

    Eisenbud, M.; Linsalata, P.; Penna Franca, E.


    An important question that must be considered in assessing the long-term effect of high-level waste isolation in geological repositories is how the actinide elements would behave if a nuclear waste repository should be exposed by erosion or be intruded by ground water. A substantial literature has accumulated concerning the behavior of the transuranic actinide elements in the environment, but most of the research until now has been concerned with fallout from nuclear weapons tests or with contamination in the environments of major atomic energy production plants. These studies are only partially relevant to risk assessment of stored radioactive wastes because such contaminants have chemical and physical forms different from those that would exist in a nuclear waste repository. Moreover, the long-term effects of geochemical processes on the behavior of the actinide elements cannot be studied because these elements were first produced by artificial means only 40 years ago

  12. Predicting Health Care Utilization After Behavioral Health Referral Using Natural Language Processing and Machine Learning


    Roysden, Nathaniel; Wright, Adam


    Mental health problems are an independent predictor of increased healthcare utilization. We created random forest classifiers for predicting two outcomes following a patient’s first behavioral health encounter: decreased utilization by any amount (AUROC 0.74) and ultra-high absolute utilization (AUROC 0.88). These models may be used for clinical decision support by referring providers, to automatically detect patients who may benefit from referral, for cost management, or for risk/protection ...

  13. Predicting Health Care Utilization After Behavioral Health Referral Using Natural Language Processing and Machine Learning. (United States)

    Roysden, Nathaniel; Wright, Adam


    Mental health problems are an independent predictor of increased healthcare utilization. We created random forest classifiers for predicting two outcomes following a patient's first behavioral health encounter: decreased utilization by any amount (AUROC 0.74) and ultra-high absolute utilization (AUROC 0.88). These models may be used for clinical decision support by referring providers, to automatically detect patients who may benefit from referral, for cost management, or for risk/protection factor analysis.

  14. No Man is an Island: Social Distance, Network Flow, and Other-Regarding Behaviors in a Natural Field Experiment

    Directory of Open Access Journals (Sweden)



    Full Text Available A natural field experiment is designed to explore the impacts of social distanceand network flow on other-regarding behaviors. A greater degree ofcommunication between the voluntary organization and volunteers was found toreduce their social distance and thereby improve volunteering commitment. Theimprovement was even more notable if the party initiating communication was thevoluntary organization. Two other practical means of lessening social distancewere for volunteers to learn more about other volunteers, and for informationtobe dispersed throughout the organization more rapidly. Additionally, this studyshows a reversed “U-shaped” relationship between network flow and volunteeringcommitment.

  15. Natural history of Ctenus medius Keyserling, 1891 (Aranae, Ctenidae) II: life cycle and aspects of reproductive behavior under laboratory conditions




    Ctenus medius Keyserling, 1891 is a wandering spider common in the Brazilian Atlantic Forest. It has been the subject of few studies. Thus, this work aims to elucidate aspects of its natural history, such as the life cycle and reproductive behavior of this species, through laboratory and field observations. Two females with egg sacs were observed in the laboratory and one was observed in field (Barra Mansa, 22º32'S and 44º10'W) until the emergence of the spiderlings. For observation of the im...

  16. Weight, Mass, and Gravity: Threshold Concepts in Learning Science (United States)

    Bar, Varda; Brosh, Yaffa; Sneider, Cary


    Threshold concepts are essential ideas about the natural world that present either a barrier or a gateway to a deep understanding of science. Weight, mass, and gravity are threshold concepts that underpin students' abilities to understand important ideas in all fields of science, embodied in the performance expectations in the Next Generation…

  17. The sorption behavior of Cs+ ion on commercially available natural Vermiculite

    International Nuclear Information System (INIS)

    Patra, Kankan; Deokar, U.V.; Khot, A.R.; Mathew, P.; Ganesh, G.; Tripathi, R.M.


    Progress of the nuclear energy programme depends upon the effective management of nuclear waste generated during the different stages of nuclear fuel cycle. The radioactive wastes require suitable and safe management from beginning of their generation until the storage in repository. The backfill layer is considered one of the most important components of the engineering barrier of the repository. It is important to know the properties of the materials that can be used as backfill layer. Vermiculite was selected for the research as it is one of the promising candidates for the natural barrier. The objective of this research was to characterize vermiculite clays in order to evaluate the viability of their use in the backfill layer, one of the radioactive waste repository barriers. Efforts were made to evaluate the distribution of Cesium ions and there thermodynamics parameter in natural vermiculite in Tarapur plant site

  18. Behavioral responses of honey bees (Apis mellifera) to natural and synthetic xenobiotics in food


    Liao, Ling-Hsiu; Wu, Wen-Yen; Berenbaum, May R.


    While the natural foods of the western honey bee (Apis mellifera) contain diverse phytochemicals, in contemporary agroecosystems honey bees also encounter pesticides as floral tissue contaminants. Whereas some ubiquitous phytochemicals in bee foods up-regulate detoxification and immunity genes, thereby benefiting nestmates, many agrochemical pesticides adversely affect bee health even at sublethal levels. How honey bees assess xenobiotic risk to nestmates as they forage is poorly understood. ...

  19. Phase Behavior and Physical Parameters of Natural Gas Mixture with CO2

    Directory of Open Access Journals (Sweden)

    Dali Hou


    Full Text Available The two-flash experiment, constant composition expansion experiment, saturation pressure measurement experiment, and phase transition observation experiment from well bottom hole to well head of four high CO2 content natural gas samples were carried out by using the JEFRI-PVT apparatus made from DBR Company of Canada. The experimental results show that in the four high CO2 content gas samples no phase transitions will take place at temperatures greater than 35°C. In the gas-liquid two-phase region, saturation pressures, critical pressure, critical temperature, and an integrated P-T phase diagram of different CO2 content natural gases are calculated by using the modified PR equation of state and modified (T equation proposed by Saffari. The deviations between the saturation pressure calculated by using the model proposed in this study and experimental measured saturation pressure are very small; the average relative error is only 2.86%. Thus, the model can be used to predict the phase equilibrium parameters of high CO2 content natural gas.

  20. Composition, phase behavior and thermal stability of natural edible fat from rambutan (Nephelium lappaceum L.) seed. (United States)

    Solís-Fuentes, Julio A; Camey-Ortíz, Guadalupe; Hernández-Medel, María del Rosario; Pérez-Mendoza, Francisco; Durán-de-Bazúa, Carmen


    In this paper, the chemical composition, the main physicochemical properties, phase behavior and thermal stability of rambutan (Nephelium lappaceum L.) seed fat were studied. These results showed that the almond-like decorticated seed represents 6.1% of the wet weight fruit and is: 1.22% ash, 7.80% protein, 11.6% crude fiber, 46% carbohydrates, and 33.4% fat (d.b.). The main fatty acids in the drupe fat were 40.3% oleic, 34.5% arachidic, 6.1% palmitic, 7.1% stearic, 6.3% gondoic, and 2.9% behenic; the refraction, saponification and iodine values were 1.468, 186, and 47.0, respectively. The phase behavior analysis showed relatively simple crystallization and melting profiles: crystallization showed three well-differentiated groups of triglycerides around maximum peaks at +30.8, +15.6 and -18.1 degrees C; the fat-melting curve had a range between -14.5 and +51.8 degrees C with a fusion enthalpy of 124.3 J/g. The thermal stability analyzed in an inert atmosphere of N(2) and in a normal oxidizing atmosphere, showed that in the latter, fat decomposition begins at 237.3 degrees C and concludes at 529 degrees C, with three stages of decomposition. According to these results, rambutan seed fat has physicochemical and thermal characteristics that may become interesting for specific applications in several segments of the food industry.

  1. Capturing the continuous complexity of natural behavior in the movement of C. elegans (United States)

    Ahamed, Tosif; Stephens, Greg

    Progress in imaging and machine vision has made it possible to quantify animal movement at unprecedented spatiotemporal scales and resulting analyses have suggested a picture of behavior composed of discrete, stereotyped motifs and transitions between them. However this description is only an approximation to more fundamental continuous dynamics and ignores the variability within each motif. Here, we combine video tracking of the nematode C. elegans with concepts from nonlinear dynamics to reconstruct the phase space of the worm's locomotion. We show that the dynamics lie on a 6D attractor, which is globally composed of three sets of cyclic trajectories that form the animal's most stereotyped behaviors: forward, backward and turning locomotion. In contrast to such global stereotypy, we also observe substantial local variability, which is reflected in positive Lyapunov exponents for each set of cycles. Across the full attractor we find that the Lyapunov spectrum is symmetric about a small negative value, suggesting a dissipative Hamiltonian structure in the underlying dynamics. Finally, we estimate the Kolmogorov-Sinai entropy through the sum of the positive exponents to show that local variability decreases as the animals adapt from a diffusive to a ballistic search strategy.

  2. Aggressive behavior and its associations with posttraumatic stress and academic achievement following a natural disaster. (United States)

    Scott, Brandon G; Lapré, Genevieve E; Marsee, Monica A; Weems, Carl F


    Despite an abundance of evidence linking maltreatment and violence-related trauma exposure to externalizing problems in youth, there is surprisingly little evidence to support a direct link between disaster exposure and youth aggressive behavior. This study tested the theory that there is primarily an indirect association between disaster exposure and aggression via posttraumatic stress disorder (PTSD) symptoms. The current study also examined the association between aggression and academic achievement. A sample of 191 4th- to 8th-grade minority youth who experienced Hurricane Katrina were assessed for aggressive behavior using the Peer Conflict Scale (PCS), disaster exposure, PTSD symptoms, and academic achievement. Structural equation modeling of the set of associations was consistent with the theory suggesting that there is an indirect link between disaster exposure and aggression through PTSD symptoms. Aggression was negatively associated with academic achievement, and modeling indicated that the set of associations was age and gender invariant. Findings advance the theoretical understanding of the linkage between aggression and disaster exposure. Findings also support the utility of the PCS in disaster research and the link between PCS scores and academic achievement.

  3. Thermoluminescent behavior of polyminerals from irradiated natural species (peppermint, pepper and origanum)

    International Nuclear Information System (INIS)

    Cruz Z, E.; Calderon, T.; Pineda, S.; Guzman M, A.; Gastelum, S.; Barboza F, M.; Calderon, T.


    The thermoluminescent behaviour of polyminerals from natural species was obtained in order to identify irradiated samples. The polyminerals was separated from organic part in the samples using methanol-water mixed 40:60. The commercial samples was exposured from 1 to 40 kGy in Gammabeam 651PT facility irradiator at National University of Mexico (UNAM). The glow curves from polyminerals shows a good behaviour for each dose, and the TL emission decays was present for 180 days storage in a dark room at room temperature. The maximum TL signals was located in around 220 for the samples, it is closely to TL emission from quartz and feldspars. (Author)

  4. The high-pressure behavior of an Al- and Fe-rich natural orthopyroxene

    DEFF Research Database (Denmark)

    Nestola, F.; Boffa Ballaran, T.; Balic Zunic, Tonci


    A single crystal of a natural orthopyroxene with composition M2[Fe2+0.818Mg0.156Ca0.010Mn0.016]M1[Fe2+0.081 Mg0.767Al0.084Fe3+0.068]TA[Si]TB[Si0.848Al0.152]O6 and space group Pbca (sample S95) was investigated at high pressure by X-ray diffraction using a diamond-anvil cell up to 9.56 GPa. No phase...

  5. SAS3D analysis of natural convection boiling behavior in the Sodium Boiling Test Facility

    Energy Technology Data Exchange (ETDEWEB)

    Klein, G.; Dunn, F.


    The objective of the initial phase of testing in the Sodium Boiling Test (SBT) Facility, at the Oak Ridge National Laboratory, was to determine the maximum power that could be transferred by a simulated breeder reactor coolant subchannel when the coolant flow is driven by natural convection. In order to aid in the evaluation of the experimental data and to help understand the flow regimes present at the various power levels examined during this test program, a SAS3D computer model of the SBT Facility was developed.

  6. Effect of swirling device on flow behavior in a supersonic separator for natural gas dehydration

    DEFF Research Database (Denmark)

    Wen, Chuang; Li, Anqi; Walther, Jens Honore


    is designed for an annular supersonic separator. The supersonic swirling separation flow of natural gas is calculated using the Reynolds Stress model. The results show that the viscous heating and strong swirling flow cause the adverse pressure in the annular channel, which may negatively affect......The supersonic separator is a revolutionary device to remove the condensable components from gas mixtures. One of the key issues for this novel technology is the complex supersonic swirling flow that is not well understood. A swirling device composed of an ellipsoid and several helical blades...

  7. Acute-phase protein behavior in dairy cattle herd naturally infected with Trypanosoma vivax. (United States)

    Sampaio, Paulo Henrique; Fidelis Junior, Otavio Luiz; Marques, Luiz Carlos; Machado, Rosangela Zacarias; Barnabé, Patrícia de Athayde; André, Marcos Rogério; Balbuena, Tiago Santana; Cadioli, Fabiano Antonio


    Trypanosoma vivax is a hemoprotozoon that causes disease in cattle and is difficult to diagnose. The host-parasite relationship in cattle that are infected by T. vivax has only been poorly studied. In the present study, a total of 429 serum proteinograms were produced from naturally infected animals (NIF) and were compared with 50 samples from control animals (C). The total protein, IgA band, complement C3 β chain band, albumin band, antitrypsin band, IgG band, haptoglobin band, complement C3c α chain band and protein HP-20 band presented higher levels in the serum proteinograms of the NIF group. Inter-alpha-trypsin inhibitor heavy chain H4, α2-macroglobulin, complement C6, ceruloplasmin, transferrin band and apolipoprotein A1 band presented lower levels in this group. There was no significant difference (pNIF and C groups. Acute phase proteins may be useful for understanding the host-parasite relationship, since the antitrypsin band was only present in the NIF group. This can be used as an indicator for infection in cattle that are naturally infected by T. vivax. Copyright © 2015 Elsevier B.V. All rights reserved.

  8. The second law analysis of natural gas behavior within a vortex tube

    Directory of Open Access Journals (Sweden)

    Kargaran Mahyar


    Full Text Available Vortex tube is a simple device without a moving part which is capable of separating hot and cold gas streams from a higher pressure inlet gas stream. The mechanism of energy separation has been investigated by several scientists and second law approach has emerged as an important tool for optimizing the vortex tube performance. Here, a thermodynamic model has been used to investigate vortex tube energy separation. Further, a method has been proposed for optimizing the vortex tube based on the rate of entropy generation obtained from experiments. Also, an experimental study has been carried out to investigate the effects of the hot tube length and cold orifice diameter on entropy generation within a vortex tube with natural gas as working fluid. A comparison has been made between air and natural gas as working fluids. The results show that the longest tube generates lowest entropy for NG. For air, it is middle tube which generates lowest entropy. Integration of entropy generation for all available cold mass fractions unveiled that an optimized value for hot tube length and cold orifice diameter is exist.

  9. Oscillatory Threshold Logic (United States)

    Borresen, Jon; Lynch, Stephen


    In the 1940s, the first generation of modern computers used vacuum tube oscillators as their principle components, however, with the development of the transistor, such oscillator based computers quickly became obsolete. As the demand for faster and lower power computers continues, transistors are themselves approaching their theoretical limit and emerging technologies must eventually supersede them. With the development of optical oscillators and Josephson junction technology, we are again presented with the possibility of using oscillators as the basic components of computers, and it is possible that the next generation of computers will be composed almost entirely of oscillatory devices. Here, we demonstrate how coupled threshold oscillators may be used to perform binary logic in a manner entirely consistent with modern computer architectures. We describe a variety of computational circuitry and demonstrate working oscillator models of both computation and memory. PMID:23173034

  10. Effects of copper and titanium on the corrosion behavior of newly fabricated nanocrystalline aluminum in natural seawater

    International Nuclear Information System (INIS)

    Sherif, El-Sayed M.; Ammar, Hany Rizk; Khalil, Khalil Abdelrazek


    Graphical abstract: - Highlights: • We fabricated nanocrystalline Al and some of its alloys by mechanical alloying method. • The corrosion behavior of the fabricated materials in natural seawater was reported. • We found that Al suffers both uniform and localized corrosion in the seawater. • The presence of Cu significantly decreased the corrosion of Al. • The addition of Ti to the Al–Cu alloy presented more protection to Al against corrosion. - Abstract: Fabrication of a newly nanocrystalline Al and two of its alloys, namely Al–10%Cu; and Al–10%Cu–5%Ti has been carried out using mechanical alloying (MA) technique. The corrosion behavior of these materials in aerated stagnant Arabian Gulf seawater (AGSW) at room temperature has been reported. Cyclic potentiodynamic polarization (CPP), chronoamperometric current-time (CCT) and electrochemical impedance spectroscopy (EIS) measurements along with scanning electron microscopy (SEM) and X-ray energy dispersive (EDX) investigations were employed to report the corrosion behavior of the fabricated materials. All results indicated that Al suffers both uniform and localized corrosion in the AGSW test solution. The presence of 10%Cu decreases the corrosion current density, the anodic and cathodic currents and corrosion rate and increases the corrosion resistance of Al. The addition of 5%Ti to the Al–10%Cu alloy produced further decreases in the corrosion parameters. Measurements together confirmed that the corrosion of the fabricated materials in AGSW decreases in the order Al > Al–10%Cu > Al–10%Cu–5%Ti

  11. Effects of copper and titanium on the corrosion behavior of newly fabricated nanocrystalline aluminum in natural seawater

    Energy Technology Data Exchange (ETDEWEB)

    Sherif, El-Sayed M., E-mail: [Mechanical Engineering Department, College of Engineering, King Saud University, P.O. Box 800, Al-Riyadh 11421 (Saudi Arabia); Electrochemistry and Corrosion Laboratory, Department of Physical Chemistry, National Research Centre , (NRC), Dokki, 12622, Cairo 8 (Egypt); Ammar, Hany Rizk [Metallurgical and Materials Engineering Department, Faculty of Petroleum and Mining Engineering, Suez University, Suez (Egypt); Khalil, Khalil Abdelrazek [Metallurgical and Materials Engineering Department, Faculty of Petroleum and Mining Engineering, Suez University, Suez (Egypt); Mechanical Design and Materials Department, Faculty of Energy Engineering, Aswan University, Aswan (Egypt)


    Graphical abstract: - Highlights: • We fabricated nanocrystalline Al and some of its alloys by mechanical alloying method. • The corrosion behavior of the fabricated materials in natural seawater was reported. • We found that Al suffers both uniform and localized corrosion in the seawater. • The presence of Cu significantly decreased the corrosion of Al. • The addition of Ti to the Al–Cu alloy presented more protection to Al against corrosion. - Abstract: Fabrication of a newly nanocrystalline Al and two of its alloys, namely Al–10%Cu; and Al–10%Cu–5%Ti has been carried out using mechanical alloying (MA) technique. The corrosion behavior of these materials in aerated stagnant Arabian Gulf seawater (AGSW) at room temperature has been reported. Cyclic potentiodynamic polarization (CPP), chronoamperometric current-time (CCT) and electrochemical impedance spectroscopy (EIS) measurements along with scanning electron microscopy (SEM) and X-ray energy dispersive (EDX) investigations were employed to report the corrosion behavior of the fabricated materials. All results indicated that Al suffers both uniform and localized corrosion in the AGSW test solution. The presence of 10%Cu decreases the corrosion current density, the anodic and cathodic currents and corrosion rate and increases the corrosion resistance of Al. The addition of 5%Ti to the Al–10%Cu alloy produced further decreases in the corrosion parameters. Measurements together confirmed that the corrosion of the fabricated materials in AGSW decreases in the order Al > Al–10%Cu > Al–10%Cu–5%Ti.

  12. Development, calibration and performance of an HIV transmission model incorporating natural history and behavioral patterns: application in South Africa. (United States)

    McCormick, Alethea W; Abuelezam, Nadia N; Rhode, Erin R; Hou, Taige; Walensky, Rochelle P; Pei, Pamela P; Becker, Jessica E; DiLorenzo, Madeline A; Losina, Elena; Freedberg, Kenneth A; Lipsitch, Marc; Seage, George R


    Understanding HIV transmission dynamics is critical to estimating the potential population-wide impact of HIV prevention and treatment interventions. We developed an individual-based simulation model of the heterosexual HIV epidemic in South Africa and linked it to the previously published Cost-Effectiveness of Preventing AIDS Complications (CEPAC) International Model, which simulates the natural history and treatment of HIV. In this new model, the CEPAC Dynamic Model (CDM), the probability of HIV transmission per sexual encounter between short-term, long-term and commercial sex worker partners depends upon the HIV RNA and disease stage of the infected partner, condom use, and the circumcision status of the uninfected male partner. We included behavioral, demographic and biological values in the CDM and calibrated to HIV prevalence in South Africa pre-antiretroviral therapy. Using a multi-step fitting procedure based on Bayesian melding methodology, we performed 264,225 simulations of the HIV epidemic in South Africa and identified 3,750 parameter sets that created an epidemic and had behavioral characteristics representative of a South African population pre-ART. Of these parameter sets, 564 contributed 90% of the likelihood weight to the fit, and closely reproduced the UNAIDS HIV prevalence curve in South Africa from 1990-2002. The calibration was sensitive to changes in the rate of formation of short-duration partnerships and to the partnership acquisition rate among high-risk individuals, both of which impacted concurrency. Runs that closely fit to historical HIV prevalence reflect diverse ranges for individual parameter values and predict a wide range of possible steady-state prevalence in the absence of interventions, illustrating the value of the calibration procedure and utility of the model for evaluating interventions. This model, which includes detailed behavioral patterns and HIV natural history, closely fits HIV prevalence estimates.

  13. Coupled deformation and fluid-flow behavior of a natural fracture in the CSM in situ test block

    International Nuclear Information System (INIS)

    Gertsch, L.S.


    The primary goal was the evaluation of an in situ block test as a data source for modeling the coupled flow and mechanical behavior of natural rock fractures. The experiments were conducted with the Colorado School of Mines in situ test block, an 8 m 3 (280 ft 3 ) gneiss cube which has been the focus of several previous studies. A single continuous fracture within the block was surrounded with instruments to measure stresses, deformations, and gas conductivity. The setup was subjected to combinations of normal and shear stress by pressurizing the block sides differentially with hydraulic flatjacks. The induced fracture deformation, as measured by two separate sensor systems, did not correlate closely with the fracture conductivity changes or with each other. The test fracture is more complicated physically than two parallel rock faces. Many joints which were not detected by mapping intersect the test fracture and strongly influence its behavior. These invisible joints create sub-blocks which react complexly to changes in applied load. The flow tests reflected the aggregate sub-block dislocations in the flow path. The deformation readings, however, were the movements of discrete points sparsely located among the sub-blocks. High-confidence extrapolation of block test results to large volumes, such as required for nuclear waste repository design, is not feasible currently. Present instrumentation does not sample rock mass behavior in situ at the proper scales. More basically, however, a fundamental gap exists between the nature of jointed rock and our conception of it. Therefore, the near-field rock mass must be discounted as an easily controllable barrier to groundwater flow, until radically different approaches to rock mass testing and modeling are developed

  14. The effect of various naturally occurring metal-binding compounds on the electrochemical behavior of aluminum

    Energy Technology Data Exchange (ETDEWEB)

    Hansen, D.C.; McCafferty, E. [Naval Research lab., Washington, DC (United States)


    Naturally occurring biological molecules are of considerable interest as possible corrosion inhibitors because of increased attention on the development of environmentally compatible, nonpolluting corrosion inhibitors. A hydroxamate yeast siderophore (rhodotorulic acid), a catecholate bacterial siderophore (parabactin), an adhesive protein from the blue mussel Mytilus edulis, and two metal-binding compounds isolated from the tomato and sunflower roots, namely, chlorogenic and caffeic acid, respectively, were adsorbed from solution onto pure aluminum (99.9995%) and their effect on the critical pitting potential and polarization resistance in deaerated 0.1 M NaCl was measured. These measurements were made using anodic polarization and ac impedance spectroscopy. The catechol-containing siderophore has an inhibitive effect on the critical pitting potential of aluminum in 0.1 M NaCl and increases the polarization resistance of the metal over time. The adhesive protein from the blue mussel is also effective in inhibiting the pitting of aluminum.

  15. Unsteady three-dimensional behavior of natural convection in horizontal annulus

    International Nuclear Information System (INIS)

    Ohya, Toshizo; Miki, Yasutomi; Morita, Kouji; Fukuda, Kenji; Hasegawa, Shu


    An numerical analysis has been performed on unsteady three-dimensional natural convection in a concentric horizontal annulus filled with air. The explicit leap-frog scheme is used for integrating three-dimensional time-dependent equations and the fast Fourier transform (FFT) for solving the Poisson equations for pressure. An oscillatory flow is found to occur at high Rayleigh numbers, which agree qualitatively with the experimental observation made by Bishop et al. An experiment is also conducted to measure temperature fluctuations; a comparison between periods of fluctuations obtained numerically and experimentally shows a good agreement. Numerical calculations yield various statistical parameters of turbulence at higher Rayleigh numbers, which wait experimental verificaions, however. (author)

  16. Microstructure, molecular weight and thermal behavior of natural rubber (NR) from mangabeira (Hancornia speciosa)

    International Nuclear Information System (INIS)

    Santos, Expedito Flavio dos; Feitosa, Judith P.A.; Ricardo, Nagila M.P.S.


    The natural rubber (NR) from Hancornia speciosa contains characteristics that turns it a good alternative in elastomers supply. The NMR and IR spectra showed that the rubber of mangabeira is composed fundamentally by poly(1,4-cis-isoprene). The rubber molecular weight obtained by GPC and viscometry was 2,0x10 6 and 1,3x10 6 g/mol, respectively, in good agreement with the values determined for seringueira and manicoba NR. The glass transition temperature obtained by DSC (Tg = - 65 deg C) showed the mangabeira rubber is ideal to be utilized in regions of cold climate without compromising its mechanical properties. The rubber has also good thermal stability up to 213 deg C, as indicated by TG curves. This results indicated that the mangabeira NR can be effectively used in vulcanized articles or to be added to asphalt. (author)

  17. Effects of Mg Addition with Natural Aging Time on Two-Step Aging Behavior in Al-Mg-Si Alloys. (United States)

    Im, Jiwoo; Kim, JaeHwang


    Influence of Mg contents with the natural aging (NA) time on the two-step aging behavior in Al-Mg-Si alloys is studied. Hardness is gradually increased during NA in the 3M4S, whereas dramatic increase of hardness after NA for 3.6 ks is confirmed in the 9M4S. Similar peak hardness is confirmed between the two-step aged and single aged samples in the 3M4S. It means that there is no negative effect of two-step aging. On the other hand, the peak hardness is decreased for the naturally-aged sample compared with the single aged one in the 9M4S. Formation of Cluster (1) is accelerated by the Mg addition, resulting in the negative effect of two-step aging. Meanwhile, the formation of the precipitates is accelerated by Mg addition during aging at 170 °C. The precipitate formed at the peak hardness during aging at 170 °C after natural aging for 43.2 ks is identified as the β″ phase based on the high resolution transmission electron microscope observation.

  18. DBSSP - A computer program for simulation of controlled circulation boiler and natural circulation boiler start up behavior

    International Nuclear Information System (INIS)

    Li Bin; Chen Tingkuan; Yang Dong


    In this paper, a computer program, Drum Boiler Start-up Simulation Program (DBSSP), is developed for simulating the start up behavior of controlled circulation and natural circulation boilers. The mathematical model developed here is based on the first principles of mass, energy and momentum conservations. In the boiler model, heat transfer in the waterwall, the superheater, the reheater and the economizer is simulated by the distributing parameter method, while heat transfer in the drum and the downcomer is simulated by lumped parameter analysis. The program can provide detailed flow and thermodynamic characteristics of the boiler components. The development of this program is based only on design data, so it can be used for any subcritical, controlled or natural circulation boiler. The simulation results were compared with experimental measurements, and good agreements between them were found. This program is expected to be useful for predicting the characteristics and the performance of controlled circulation and natural circulation boilers during the start up process. It also can be used to optimize a start up system for minimum start up time

  19. Do multiple body modifications alter pain threshold? (United States)

    Yamamotová, A; Hrabák, P; Hříbek, P; Rokyta, R


    In recent years, epidemiological data has shown an increasing number of young people who deliberately self-injure. There have also been parallel increases in the number of people with tattoos and those who voluntarily undergo painful procedures associated with piercing, scarification, and tattooing. People with self-injury behaviors often say that they do not feel the pain. However, there is no information regarding pain perception in those that visit tattoo parlors and piercing studios compared to those who don't. The aim of this study was to compare nociceptive sensitivity in four groups of subjects (n=105, mean age 26 years, 48 women and 57 men) with different motivations to experience pain (i.e., with and without multiple body modifications) in two different situations; (1) in controlled, emotionally neutral conditions, and (2) at a "Hell Party" (HP), an event organized by a piercing and tattoo parlor, with a main event featuring a public demonstration of painful techniques (burn scars, hanging on hooks, etc.). Pain thresholds of the fingers of the hand were measured using a thermal stimulator and mechanical algometer. In HP participants, information about alcohol intake, self-harming behavior, and psychiatric history were used in the analysis as intervening variables. Individuals with body modifications as well as without body modifications had higher thermal pain thresholds at Hell Party, compared to thresholds measured at control neutral conditions. No such differences were found relative to mechanical pain thresholds. Increased pain threshold in all HP participants, irrespectively of body modification, cannot be simply explained by a decrease in the sensory component of pain; instead, we found that the environment significantly influenced the cognitive and affective component of pain.

  20. Nature vs nurture: are leaders born or made? A behavior genetic investigation of leadership style. (United States)

    Johnson, A M; Vernon, P A; McCarthy, J M; Molson, M; Harris, J A; Jang, K L


    With the recent resurgence in popularity of trait theories of leadership, it is timely to consider the genetic determination of the multiple factors comprising the leadership construct. Individual differences in personality traits have been found to be moderately to highly heritable, and so it follows that if there are reliable personality trait differences between leaders and non-leaders, then there may be a heritable component to these individual differences. Despite this connection between leadership and personality traits, however, there are no studies of the genetic basis of leadership using modern behavior genetic methodology. The present study proposes to address the lack of research in this area by examining the heritability of leadership style, as measured by self-report psychometric inventories. The Multifactor Leadership Questionnaire (MLQ), the Leadership Ability Evaluation, and the Adjective Checklist were completed by 247 adult twin pairs (183 monozygotic and 64 same-sex dizygotic). Results indicated that most of the leadership dimensions examined in this study are heritable, as are two higher level factors (resembling transactional and transformational leadership) derived from an obliquely rotated principal components factors analysis of the MLQ. Univariate analyses suggested that 48% of the variance in transactional leadership may be explained by additive heritability, and 59% of the variance in transformational leadership may be explained by non-additive (dominance) heritability. Multivariate analyses indicated that most of the variables studied shared substantial genetic covariance, suggesting a large overlap in the underlying genes responsible for the leadership dimensions.

  1. Hydraulic Behavior and Chemical Characterization of Lapilli as Material for Natural Filtering of Slurry

    Directory of Open Access Journals (Sweden)

    Nereida Falcón-Cardona


    Full Text Available Livestock effluents are a beneficial nutrient supply for crops, whereby their use is critical to ensure the sustainability of the farms global management. However, they can cause serious ecological problems if misused, polluting soils and groundwater. Combining “soft technology” and local materials is a low cost solution in terms of finance and energy. The REAGUA project (REuso AGUA, Water reuse in Spanish analyzes the possibility of using “picon” (lapilli as a material for the treatment of liquid manure from ruminants, for later use in subsurface drip irrigation system to produce forage and biofuels, in which the soil acts as a subsequent advanced treatment. A three-phase system, in which the effluent was poured with a vertical subsurface flow in an unsaturated medium, is designed. In order to determine the management conditions that optimize the filter, it was necessary to characterize the hydraulic behavior of lapilli and its ability to remove substances. Using three lapilli-filled columns, unsaturated flux, and a ruminant effluent, the reduction of chemical oxygen demand (COD, biochemical oxygen demand after 5 days (BOD5 and ammonia, phosphorus and suspension solids (SS obtained was over 80%, 90%, and 95% respectively, assumable values for irrigation.

  2. Dental prostheses mimic the natural enamel behavior under functional loading: A review article

    Directory of Open Access Journals (Sweden)

    Ahmed A. Madfa


    Full Text Available Alumina- and zirconia-based ceramic dental restorations are designed to repair functionality as well as esthetics of the failed teeth. However, these materials exhibited several performance deficiencies such as fracture, poor esthetic properties of ceramic cores (particularly zirconia cores, and difficulty in accomplishing a strong ceramic–resin-based cement bond. Therefore, improving the mechanical properties of these ceramic materials is of great interest in a wide range of disciplines. Consequently, spatial gradients in surface composition and structure can improve the mechanical integrity of ceramic dental restorations. Thus, this article reviews the current status of the functionally graded dental prostheses inspired by the dentino-enamel junction (DEJ structures and the linear gradation in Young's modulus of the DEJ, as a new material design approach, to improve the performance compared to traditional dental prostheses. This is a remarkable example of nature's ability to engineer functionally graded dental prostheses. The current article opens a new avenue for recent researches aimed at the further development of new ceramic dental restorations for improving their clinical durability.

  3. Curing kinetics and mechanical behavior of natural rubber reinforced with pretreated carbon nanotubes

    International Nuclear Information System (INIS)

    Sui, G.; Zhong, W.H.; Yang, X.P.; Yu, Y.H.


    To significantly improve the performance of rubber materials, fundamental studies on rubber nanocomposites are necessary. The curing kinetics and vulcanizate properties of carbon nanotubes (CNTs)/natural rubber (NR) nanocomposites were analyzed in this paper. The pretreatment of CNTs was carried out by acid bath followed by ball milling with HRH bonding systems in experiments. The CNT/NR nanocomposites were prepared through solvent mixing on the basis of pretreatment of CNTs. The surface characteristic of CNTs and physical interaction between CNTs and NR macromolecules were analyzed by Fourier transform infrared spectroscopy (FT-IR). The vulcanization kinetics of CNT/NR nanocomposites were studied contrasting with the neat NR. The quality of the NR vulcanizates was assessed through static and dynamic mechanical property tests and scanning electron microscope (SEM). Curing kinetic parameters of the neat NR and CNT/NR nanocomposites were obtained from experiments; the results indicated that the presence of CNTs affects the curing process of the NR, and additional heating is required to cure CNT/NR nanocomposites due to its higher active energy. The dispersion of pretreated CNTs in the rubber matrix and interfacial adhesion between them were obviously improved. The physical and mechanical properties of the CNT/NR nanocomposites showed considerable increases by incorporation of the pretreated CNTs compared to the neat NR and untreated CNTs-filled NR nanocomposites

  4. Neutron shielding behavior of thermoplastic natural rubber/boron carbide composites (United States)

    Mat Zali, Nurazila; Yazid, Hafizal; Megat Ahmad, Megat Harun Al Rashid


    Many shielding materials have been designed against the harm of different types of radiation to the human body. Today, polymer-based lightweight composites have been chosen by the radiation protection industry. In the present study, thermoplastic natural rubber (TPNR) composites with different weight percent of boron carbide (B4C) fillers (0% to 30%) were fabricated as neutron shielding through melt blending method. Neutron attenuation properties of TPNR/B4C composites have been investigated. The macroscopic cross section (Σ), half value layer (HVL) and mean free path length (λ) of the composites have been calculated and the transmission curves have been plotted. The obtained results show that Σ, HVL and λ greatly depend on the B4C content. Addition of B4C fillers into TPNR matrix were found to enhance the macroscopic cross section values thus decrease the mean free path length (λ) and half value layer (HVL) of the composites. The transmission curves exhibited that the neutron transmission of the composites decreased with increasing shielding thickness. These results showed that TPNR/B4C composites have high potential for neutron shielding applications.

  5. Behavioral responses of honey bees (Apis mellifera) to natural and synthetic xenobiotics in food. (United States)

    Liao, Ling-Hsiu; Wu, Wen-Yen; Berenbaum, May R


    While the natural foods of the western honey bee (Apis mellifera) contain diverse phytochemicals, in contemporary agroecosystems honey bees also encounter pesticides as floral tissue contaminants. Whereas some ubiquitous phytochemicals in bee foods up-regulate detoxification and immunity genes, thereby benefiting nestmates, many agrochemical pesticides adversely affect bee health even at sublethal levels. How honey bees assess xenobiotic risk to nestmates as they forage is poorly understood. Accordingly, we tested nine phytochemicals ubiquitous in nectar, pollen, or propolis, as well as five synthetic xenobiotics that frequently contaminate hives-two herbicides (atrazine and glyphosate) and three fungicides (boscalid, chlorothalonil, and prochloraz). In semi-field free-flight experiments, bees were offered a choice between paired sugar water feeders amended with either a xenobiotic or solvent only (control). Among the phytochemicals, foragers consistently preferred quercetin at all five concentrations tested, as evidenced by both visitation frequency and consumption rates. This preference may reflect the long evolutionary association between honey bees and floral tissues. Of pesticides eliciting a response, bees displayed a preference at specific concentrations for glyphosate and chlorothalonil. This paradoxical preference may account for the frequency with which these pesticides occur as hive contaminants and suggests that they present a greater risk factor for honey bee health than previously suspected.

  6. Behavior and mechanism of arsenate adsorption on activated natural siderite: evidences from FTIR and XANES analysis. (United States)

    Zhao, Kai; Guo, Huaming


    Activated natural siderite (ANS) was used to investigate its characteristics and mechanisms of As(V) adsorption from aqueous solution. Batch tests were carried out to determine effects of contact time, initial As(V) concentration, temperature, pH, background electrolyte, and coexisting anions on As(V) adsorption. Arsenic(V) adsorption on ANS well-fitted pseudo-second-order kinetics. ANS showed a high-adsorption capacity of 2.19 mg/g estimated from Langmuir isotherm at 25 °C. Thermodynamic studies indicated that As(V) adsorption on ANS was spontaneous, favorable, and endothermic. ANS adsorbed As(V) efficiently in a relatively wide pH range between 2.0 and 10.0, although the removal efficiency was slightly higher in acidic conditions than that in basic conditions. Effects of background electrolyte and coexisting anions were not significant within the concentration ranges observed in high As groundwater. Results of XRD and Fe K-edge XANES analysis suggested ANS acted as an Fe(II)/(III) hybrid system, which was quite effective in adsorbing As from aqueous solution. There was no As redox transformation during adsorption, although Fe(II) oxidation occurred in the system. Two infrared bands at 787 and 872 cm(-1) after As(V) adsorption suggested that As(V) should be predominantly adsorbed on ANS via inner-sphere bidendate binuclear surface complexes.

  7. A behavioral study of the nature of verb production deficits in Alzheimer's disease. (United States)

    Beber, Bárbara Costa; Cruz, Aline Nunes da; Chaves, Márcia L


    Patients with Alzheimer's disease (AD) may experience greater difficulty with verb production than with noun production. In this study, we sought to assess the nature of verb production deficits in AD by using verb fluency and verb naming tasks. We designed two hypotheses for this verb deficit: (1) executive impairment drives the deficit; (2) semantic impairment drives the deficit. Thirty-five patients with AD and 35 matched healthy controls participated in the study. Both groups performed a verb naming task composed of 45 pictures (low-, medium-, and high-frequency subsets) and a verb fluency task (scored for total correct words and for mean word frequency). Patients with AD were equally impaired in verb naming and verb fluency, with an effect of disease severity on verb naming. Word frequency influenced verb naming, but not verb fluency, performance. Our results indicate that verb production deficits in AD seem to be driven more by semantic than by executive impairment. Copyright © 2015 Elsevier Inc. All rights reserved.

  8. Iris pigmentation and AC thresholds. (United States)

    Roche, A F; Mukherjee, D; Chumlea, W C; Siervogel, R M


    Data from 160 White children were used to analyze possible associations between iris pigmentation and AC pure-tone thresholds. Iris pigmentation was graded from iris color using glass models of eyes, and AC thresholds were obtained under carefully controlled conditions. Analyses of variance using two groupings of iris color grades showed no evidence of an association between iris color grade and AC thresholds. Furthermore, inspection of arrays of the actual glass eye models, in conjunction with the order of mean thresholds at each test frequency, did not indicate the presence of an association between iris color grades and thresholds. It was concluded that while iris pigmentation may be related to some aspects of hearing ability, it does not appear to be related to AC thresholds in children.

  9. Albania - Thresholds I and II (United States)

    Millennium Challenge Corporation — From 2006 to 2011, the government of Albania (GOA) received two Millennium Challenge Corporation (MCC) Threshold Programs totaling $29.6 million. Albania received...

  10. Olfactory threshold in Parkinson's disease. (United States)

    Quinn, N P; Rossor, M N; Marsden, C D


    Olfactory threshold to differing concentrations of amyl acetate was determined in 78 subjects with idiopathic Parkinson's disease and 40 age-matched controls. Impaired olfactory threshold (previously reported by others) was confirmed in Parkinsonian subjects compared with controls. There was no significant correlation between olfactory threshold and age, sex, duration of disease, or current therapy with levodopa or anticholinergic drugs. In a sub-group of 14 levodopa-treated patients with severe "on-off" fluctuations, no change in olfactory threshold between the two states was demonstrable. Olfactory impairment in Parkinson's disease may involve mechanisms that are not influenced by pharmacologic manipulation of dopaminergic or cholinergic status. PMID:3819760

  11. Learning foraging thresholds for lizards

    Energy Technology Data Exchange (ETDEWEB)

    Goldberg, L.A. [Univ. of Warwick, Coventry (United Kingdom). Dept. of Computer Science; Hart, W.E. [Sandia National Labs., Albuquerque, NM (United States); Wilson, D.B. [Massachusetts Inst. of Tech., Cambridge, MA (United States)


    This work gives a proof of convergence for a randomized learning algorithm that describes how anoles (lizards found in the Carribean) learn a foraging threshold distance. This model assumes that an anole will pursue a prey if and only if it is within this threshold of the anole`s perch. This learning algorithm was proposed by the biologist Roughgarden and his colleagues. They experimentally confirmed that this algorithm quickly converges to the foraging threshold that is predicted by optimal foraging theory our analysis provides an analytic confirmation that the learning algorithm converses to this optimal foraging threshold with high probability.

  12. Transport behavior of aromatic hydrocarbons through coconut shell powder filled thermoplastic polyurethane/natural rubber blend-composites (United States)

    Balan, Aparna K.; Sreejith, M. P.; Shaniba, V.; Jinitha, T. V.; Subair, N.; Purushothaman, E.


    The transport behavior of homologous series of aromatic solvents through coconut shell powder reinforced thermoplastic polyurethane/natural rubber blend-composites have been investigated in the temperature range 30-70 °C. The diffusion and transport properties of solvents through the composites have been studied in detail, as a function of filler concentration, filler modification, penetrant size and temperature variation. Mol % uptake and transport coefficients such as diffusion coefficient, sorption coefficient and permeation coefficient were estimated and were found to be decreasing with increase in filler loading. The solvent transport is hindered at high concentrations of coconut shell powder. This observation could be correlated with the morphology of the composites. The mechanism of transport is found to be deviated from normal Fickian trend. Activation energy for diffusion is calculated from Arrhenius plots.

  13. Behavioral Responses of Cattle to Naturally Occurring Seasonal Populations of Horn Flies (Diptera: Muscidae) Under Rangeland Conditions. (United States)

    Smythe, Brandon G; Pitzer, Jimmy B; Wise, Mark E; Cibils, Andres F; Vanleeuwen, Dawn; Byford, Ronnie L


    The behavioral responses of cattle under the influence of naturally occurring seasonal horn fly, Haematobia irritans (L.), populations were evaluated under rangeland conditions. This study was replicated four times using 10 cows as the subsampling unit equipped with GPS collars scheduled to receive locational fixes every 5 min for 6 d prior to, and 6 d following horn fly insecticidal control application. Data derived from GPS collars were used to evaluate potential horn fly-induced behavioral modifications expressed during predawn, daytime, and nighttime periods. These data were used to analyze variables, which included distance travelled, daily area explored, vertical and horizontal head movements, and inferred activities such as resting, grazing, and walking. Horn fly populations were estimated using daily visual counts and were reduced significantly on animals following insecticidal application. There was no significant difference between treatment periods in any of the aforementioned analyzed variables. During the night-time hours estimated differences (pretreatment minus posttreatment) for distance travelled, area explored, and vertical head movements were 0.81 ± 0.46 km/d, 0.35 ± 0.21 km(2)/d, and 7.25 ± 5.30 counts/d, respectively. The implications of these observations are discussed. © The Authors 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email:

  14. Analytical study on thermal-hydraulic behavior of transient from forced circulation to natural circulation in JRR-3

    International Nuclear Information System (INIS)

    Hirano, Masashi; Sudo, Yukio


    Transient thermal-hydraulic behaviors of the JRR-3 which is an open-pool type research reactor has been analyzed with the THYDE-P1 code. The focal point is the thermal-hydraulic behaviors related to the core flow reversal during the transition from forced circulation downflow to natural circulation upflow. In the case of a loss-of-coolant accident (LOCA), for example, the core flow reversal is expected to occur just after the water pool isolation from the primary cooling loop with a leak. The core flow reversal should cause a sudden increase in fuel temperature and a steep decrease in the departure-from-nucleate-boiling ratio (DNBR) and the phenomenon is, therefore, very important especially for safety design and evaluation of research reactors. Major purposes of the present work are to clarify physical phenomena during the transient and to identify important parameters affecting the peak fuel temperature and the minimum DNBR. The results calculated with THYDE-P1 assuming the sequences of events of the loss-of-offsite power and LOCA help us to understand the phenomena both qualitatively and quantitatively, with respect to the safety design and evaluation. (author)

  15. Behavioral Responses of Concholepas concholepas (Bruguière, 1789) Larvae to Natural and Artificial Settlement Cues and Microbial Films. (United States)

    Rodriguez, S R; Riquelme, C; Campos, E O; Chavez, P; Brandan, E; Inestrosa, N C


    The behavioral responses of veliger larvae of the gastropod Concholepas concholepas were studied in the presence of different natural and artificial settlement cues and microbial films. Early pre-competent larvae stopped swimming, sank (due to ciliary arrests, retraction of the velum into the shell, or both), and remained inactive on the substratum when exposed to conspecific mucus and hemolymph. In both cases the effect was time-dependent and the number of larvae showing these behaviors decreased over time. Larvae exposed to NH4Cl (ammonium ion) showed a similar time- and dose-dependent response. A positive and time-dependent response was also observed when larvae were exposed to different extracellular matrix (ECM) components (i.e., collagen, gelatin, and fibronectin) and sulfated polysaccharides (i.e., carrageenan, heparin, and chondroitin sulfate). In this case the larvae remained attached to the substratum. However, the effect of sulfated polysaccharides on C. concholepas larval behavior was faster than that observed with other ECM molecules. We also studied the responses of premetamorphic C. concholepas larvae exposed to different microbial films. In chemotaxis experiments with different films, with glass as the substratum, larvae showed a significant preference for multispecific and diatoms films. When shells of C. concholepas were used as the substratum, the preference for multispecific films was clear and significant. Likewise, larvae showed velar contractions in the presence of all the films tested. Larvae exposed to multispecific films and to the microalga Prasinocladus marinus showed an increased ciliar movement. The finding that mucus and hemolymph of conspecific adults and ECM molecules (mainly sulfated polysaccharides) induce the cessation of swimming of C. concholepas larvae suggests a possible role for cell-surface receptors in mediating the larval response of marine organisms. Likewise, the positive chemotaxis responses of C. concholepas larvae to

  16. Project Pocos de Caldas Plateau: cancer research and natural radioactivity - incidence and risk behavior

    International Nuclear Information System (INIS)

    Antoniazzi, Berenice Navarro; Otero, Ubirani Barros


    It has been well established by epidemiological studies that long term exposure due to radon increases the risk of lung cancer. While smoking continues to account for the bulk of lung cancers, it is been estimated that radon accounts for around 10% of all lung cancers. There is a synergistic relationship between smoking and radon and exposure due to radon is the primary cause of lung cancer in non-smokers. Recognizing the importance of radon as a source of radiation exposure, the IAEA safety standard Radiation Protection and Safety of Radiation Sources: International Basic Safety Standards (generally referred to simply as the BSS) contains requirements aimed at reducing the associated risks. The BSS requires Member States to provide information on the levels of radon indoors and the associated health effects, and if appropriate, to establish and implement a radon action plan for controlling public exposure due to radon indoors. Although not specifically stated, it is clear that in order to decide whether or not an action plan is necessary, some measurement data must be available on the concentrations of radon present indoors. To assist in the implementation of the BSS, the Agency has also developed a Safety Guide: Protection of the Public against Exposure indoors due do Radon and Other Natural Sources of Radiation. This Safety Guide provides guidance on establishing and implementing a national radon action plan; developing national radon policy; undertaking national and regional surveys of radon in dwellings; measurement protocols; setting a reference level for dwellings; defining radon prone areas; radon control through building codes; and evaluation of programme effectiveness. While many sources of radiation exposure are not amenable to control, proven and effective building practices exist to limit the accumulation of radon in new buildings and cost-effective corrective actions have been developed to reduce high radon concentrations in existing buildings. The

  17. Behaviorism (United States)

    Moore, J.


    Early forms of psychology assumed that mental life was the appropriate subject matter for psychology, and introspection was an appropriate method to engage that subject matter. In 1913, John B. Watson proposed an alternative: classical S-R behaviorism. According to Watson, behavior was a subject matter in its own right, to be studied by the…

  18. Behavior

    NARCIS (Netherlands)

    Bouwman, L.I.


    Health behaviors are people’s actions, some purposefully deployed to promote or protect health; some thoughtlessly undertaken without concern for their potential risk to health; some consciously, even defiantly, deployed regardless of consequences to health. Risk behaviors are specific forms of

  19. Threshold Concepts and Information Literacy (United States)

    Townsend, Lori; Brunetti, Korey; Hofer, Amy R.


    What do we teach when we teach information literacy in higher education? This paper describes a pedagogical approach to information literacy that helps instructors focus content around transformative learning thresholds. The threshold concept framework holds promise for librarians because it grounds the instructor in the big ideas and underlying…

  20. Second threshold in weak interactions

    NARCIS (Netherlands)

    Veltman, M.J.G.


    The point of view that weak interactions must have a second threshold below 300 – 600 GeV is developed. Above this threshold new physics must come in. This new physics may be the Higgs system, or some other nonperturbative system possibly having some similarities to the Higgs system. The limit of

  1. Near-Threshold Ionization of Argon by Positron Impact (United States)

    Babij, T. J.; Machacek, J. R.; Murtagh, D. J.; Buckman, S. J.; Sullivan, J. P.


    The direct single-ionization cross section for Ar by positron impact has been measured in the region above the first ionization threshold. These measurements are compared to semiclassical calculations which give rise to a power law variation of the cross section in the threshold region. The experimental results appear to be in disagreement with extensions to the Wannier theory applied to positron impact ionization, with a smaller exponent than that calculated by most previous works. In fact, in this work, we see no difference in threshold behavior between the positron and electron cases. Possible reasons for this discrepancy are discussed.

  2. Nonlinear Surface Dilatational Rheology and Foaming Behavior of Protein and Protein Fibrillar Aggregates in the Presence of Natural Surfactant. (United States)

    Wan, Zhili; Yang, Xiaoquan; Sagis, Leonard M C


    The surface and foaming properties of native soy glycinin (11S) and its heat-induced fibrillar aggregates, in the presence of natural surfactant steviol glycoside (STE), were investigated and compared at pH 7.0 to determine the impact of protein structure modification on protein-surfactant interfacial interactions. The adsorption at, and nonlinear dilatational rheological behavior of, the air-water interface were studied by combining drop shape analysis tensiometry, ellipsometry, and large-amplitude oscillatory dilatational rheology. Lissajous plots of surface pressure versus deformation were used to analyze the surface rheological response in terms of interfacial microstructure. The heat treatment generates a mixture of long fibrils and unconverted peptides. The presence of small peptides in 11S fibril samples resulted in a faster adsorption kinetics than that of native 11S. The addition of STE affected the adsorption of 11S significantly, whereas no apparent effect on the adsorption of the 11S fibril-peptide system was observed. The rheological response of interfaces stabilized by 11S-STE mixtures also differed significantly from the response for 11S fibril-peptide-STE mixtures. For 11S, the STE reduces the degree of strain hardening in extension and increases strain hardening in compression, suggesting the interfacial structure may change from a surface gel to a mixed phase of protein patches and STE domains. The foams generated from the mixtures displayed comparable foam stability to that of pure 11S. For 11S fibril-peptide mixtures STE only significantly affects the response in extension, where the degree of strain softening is decreased compared to the pure fibril-peptide system. The foam stability of the fibril-peptide system was significantly reduced by STE. These findings indicate that fibrillization of globular proteins could be a potential strategy to modify the complex surface and foaming behaviors of protein-surfactant mixtures.

  3. Photoproduction of Charm Near Threshold

    Energy Technology Data Exchange (ETDEWEB)

    Brodsky, Stanley J.


    Charm and bottom production near threshold is sensitive to the multi-quark, gluonic, and hidden-color correlations of hadronic and nuclear wavefunctions in QCD since all of the target's constituents must act coherently within the small interaction volume of the heavy quark production subprocess. Although such multi-parton subprocess cross sections are suppressed by powers of 1=m{sub Q}{sup 2}, they have less phase-space suppression and can dominate the contributions of the leading-twist single-gluon subprocesses in the threshold regime. The small rates for open and hidden charm photoproduction at threshold call for a dedicated facility.

  4. The Geochemistry of Technetium: A Summary of the Behavior of an Artificial Element in the Natural Environment

    Energy Technology Data Exchange (ETDEWEB)

    Icenhower, Jonathan P.; Qafoku, Nikolla; Martin, Wayne J.; Zachara, John M.


    Interest in the chemistry of technetium has only increased since its discovery in 1937, mainly because of the large and growing inventory of 99Tc generated during fission of 235U, its environmental mobility in oxidizing conditions, and its potential radiotoxicity. For every ton of enriched uranium fuel (3% 235U) that is consumed at a typical burn-up rate, nearly 1 kg of 99Tc is generated. Thus, the mass of 99Tc produced since 1993 has nearly quadrupled, and will likely to continue to increase if more emphasis is placed on nuclear power to slow the accumulation of atmospheric greenhouse gases. In order to gain a comprehensive understanding of the interaction of 99Tc and the natural environment, we review the sources of 99Tc in the nuclear fuel cycle, its chemical properties, radiochemistry, and biogeochemical behavior. We include an evaluation of the use of Re as a chemical analog of Tc, as well as a summary of the redox potential, thermodynamics, sorption, colloidal behavior, and interaction of humic substances with Tc, and the potential for re-oxidation and remobilization of Tc(IV). What emerges is a more complicated picture of Tc behavior than that of an easily tractable transition of Tc(VII) to Tc(IV) with consequent immobilization. Reducing conditions (+200 to +100 mV Eh) are generally thought necessary to cause reduction of Tc(VII) to Tc(IV), but far more important are the presence of reducing agents, such as Fe(II) sorbed onto mineral grains. Catalysis of Tc(VII) by surface-mediated Fe(II) will bring the mobile Tc(VII) species to a lower oxidation state and will form the relatively insoluble Tc(IV)O2∙nH2O, but even as a solid, equilibrium concentrations of aqueous Tc are nearly a factor of 20× above the EPA set drinking water standards. However, sequestration of Tc(IV) into Fe(III)-bearing phases, such as goethite or other hydrous oxyhydroxides of iron, may ameliorate concerns over the mobility of Tc. Further, the outcome of many studies on terrestrial and

  5. Parton distributions with threshold resummation

    CERN Document Server

    Bonvini, Marco; Rojo, Juan; Rottoli, Luca; Ubiali, Maria; Ball, Richard D.; Bertone, Valerio; Carrazza, Stefano; Hartland, Nathan P.


    We construct a set of parton distribution functions (PDFs) in which fixed-order NLO and NNLO calculations are supplemented with soft-gluon (threshold) resummation up to NLL and NNLL accuracy respectively, suitable for use in conjunction with any QCD calculation in which threshold resummation is included at the level of partonic cross sections. These resummed PDF sets, based on the NNPDF3.0 analysis, are extracted from deep-inelastic scattering, Drell-Yan, and top quark pair production data, for which resummed calculations can be consistently used. We find that, close to threshold, the inclusion of resummed PDFs can partially compensate the enhancement in resummed matrix elements, leading to resummed hadronic cross-sections closer to the fixed-order calculation. On the other hand, far from threshold, resummed PDFs reduce to their fixed-order counterparts. Our results demonstrate the need for a consistent use of resummed PDFs in resummed calculations.

  6. Impacts of active school design on school-time sedentary behavior and physical activity: A pilot natural experiment. (United States)

    Brittin, Jeri; Frerichs, Leah; Sirard, John R; Wells, Nancy M; Myers, Beth M; Garcia, Jeanette; Sorensen, Dina; Trowbridge, Matthew J; Huang, Terry


    Children spend a significant portion of their days in sedentary behavior (SB) and on average fail to engage in adequate physical activity (PA). The school built environment may influence SB and PA, but research is limited. This natural experiment evaluated whether an elementary school designed to promote movement impacted students' school-time SB and PA. Accelerometers measured SB and PA at pre and post time-points in an intervention group who moved to the new school (n = 21) and in a comparison group experiencing no school environmental change (n = 20). Difference-in-difference (DD) analysis examined SB and PA outcomes in these groups. Measures were also collected post-intervention from an independent, grade-matched group of students in the new school (n = 21). As expected, maturational increases in SB were observed. However, DD analysis estimated that the intervention attenuated increase in SB by 81.2 ± 11.4 minutes/day (pdesign had beneficial effects on SB and LPA, but not on MVPA. Mixed results point to a need for active classroom design strategies to mitigate SB, and quick access from classrooms to areas permissive of high-intensity activities to promote MVPA. Integrating active design with programs/policies to promote PA may yield greatest impact on PA of all intensities.

  7. Complex motivated behaviors for natural rewards following a binge-like regimen of morphine administration: mixed phenotypes of anhedonia and craving after short-term withdrawal

    Directory of Open Access Journals (Sweden)

    Yunjing eBai


    Full Text Available The anhedonia-like behaviors following about one-week withdrawal from morphine were examined in the present study. Male rats were pretreated with either a binge-like morphine paradigm or daily saline injection for 5 days. Three types of natural reward were used, food reward (2.5%, 4%, 15%, 30%, 40% and 60% sucrose solutions, social reward (male rat and sexual reward (estrous female rat. For each type of natural stimulus, consummatory behavior and motivational behaviors under varied testing conditions were investigated. The results showed that the morphine-treated rats significantly reduced their consumption of 2.5% sucrose solution during the 1-hour consumption testing and their operant responding for 15%, 30% and 40% sucrose solutions under a fixed ratio 1 (FR1 schedule. However, performance under a progressive ratio (PR schedule increased in morphine-treated rats reinforced with 60% sucrose solution, but not in those reinforced with sucrose concentrations lower than 60%. Pretreatment with morphine significantly decreased the male rats’ ejaculation frequency during the 1-hour copulation testing, and impaired the maintenance of appetitive motivations to sexual and social stimuli under a free-approach condition. Moreover, the morphine-treated rats demonstrated a diminished motivation to approach social stimulus in the effort-based appetitive behavior test but showed a remarkable increase in motivation to approach sexual stimulus in the risky appetitive behavior test. These results demonstrated some complex motivated behaviors following about one week of morphine withdrawal: (1 The anhedonia-like behavior was consistently found in animals withdrawn from morphine. However, for a given reward, there was often a dissociation of the consummatory behaviors from the motivational behaviors, and whether the consummatory or the motivational anhedonia-like behaviors could be discovered heavily depended on the type and magnitude of the reward and the type

  8. Conceptions of nuclear threshold status

    International Nuclear Information System (INIS)

    Quester, G.H.


    This paper reviews some alternative definitions of nuclear threshold status. Each of them is important, and major analytical confusions would result if one sense of the term is mistaken for another. The motives for nations entering into such threshold status are a blend of civilian and military gains, and of national interests versus parochial or bureaucratic interests. A portion of the rationale for threshold status emerges inevitably from the pursuit of economic goals, and another portion is made more attraction by the derives of the domestic political process. Yet the impact on international security cannot be dismissed, especially where conflicts among the states remain real. Among the military or national security motives are basic deterrence, psychological warfare, war-fighting and, more generally, national prestige. In the end, as the threshold phenomenon is assayed for lessons concerning the role of nuclear weapons more generally in international relations and security, one might conclude that threshold status and outright proliferation coverage to a degree in the motives for all of the states involved and in the advantages attained. As this paper has illustrated, nuclear threshold status is more subtle and more ambiguous than outright proliferation, and it takes considerable time to sort out the complexities. Yet the world has now had a substantial amount of time to deal with this ambiguous status, and this may tempt more states to exploit it

  9. Threshold models in radiation carcinogenesis

    International Nuclear Information System (INIS)

    Hoel, D.G.; Li, P.


    Cancer incidence and mortality data from the atomic bomb survivors cohort has been analyzed to allow for the possibility of a threshold dose response. The same dose-response models as used in the original papers were fit to the data. The estimated cancer incidence from the fitted models over-predicted the observed cancer incidence in the lowest exposure group. This is consistent with a threshold or nonlinear dose-response at low-doses. Thresholds were added to the dose-response models and the range of possible thresholds is shown for both solid tumor cancers as well as the different leukemia types. This analysis suggests that the A-bomb cancer incidence data agree more with a threshold or nonlinear dose-response model than a purely linear model although the linear model is statistically equivalent. This observation is not found with the mortality data. For both the incidence data and the mortality data the addition of a threshold term significantly improves the fit to the linear or linear-quadratic dose response for both total leukemias and also for the leukemia subtypes of ALL, AML, and CML

  10. Tactile thresholds in healthy subjects

    Directory of Open Access Journals (Sweden)

    Metka Moharić


    Full Text Available Background: The assessment of sensory thresholds provides a method of examining the function of peripheral nerve fibers and their central connections. Quantitative sensory testing is a variant of conventional sensory testing wherein the goal is the quantification of the level of stimulation needed to produce a particular sensation. While thermal and vibratory testing are established methods in assessment of sensory thresholds, assessment of tactile thresholds with monofilaments is not used routinely. The purpose of this study was to assess the tactile thresholds in normal healthy population.Methods: In 39 healthy volunteers (19 men aged 21 to 71 years, tactile thresholds were assessed with von Frey’s hair in 7 parts of the body bilaterally.Results: We found touch sensitivity not to be dependent on age or gender. The right side was significantly more sensitive in the lateral part of the leg (p=0.011 and the left side in the medial part of the arm (p=0.022. There were also significant differences between sites (p<0.001, whereby distal parts of the body were more sensitive.Conclusions: Von Frey filaments allow the estimation of tactile thresholds without the need for complicated instrumentation.

  11. Effects of the structural nature of the anionic additives on the rheological behavior of bentonite suspensions; Effets de la nature structurelle des additifs anioniques sur le comportement rheologique de suspensions de bentonite

    Energy Technology Data Exchange (ETDEWEB)

    Adel Benchabane; Karim Bekkour [institut de mecanique des fluides et des solides, UMR CNRS ULP 7507, 2 rue Boussingault, 67000 Strasbourg (France)


    Different experimental measurements (Theology, granulometry, XRD) were carried out in order to study the main properties of bentonite suspensions in presence of anionic additives at different concentrations. These additives are: Sodium Dodecyl Sulfate (SDS) as surfactant, a flexible polymer (Sodium Carboxy Methyl Cellulose, CMC) and a semi-rigid polymer (Xanthan gum). It has been shown that the structural nature of anionic additive influences directly the mixtures viscoelastic and flow behavior. The steric effect of the surfactant modifies the Face-Edge interactions and yields changes of the mixtures rheological behavior at low deformation rates. Polymers act by coating each clay particle and prevent their agglomeration. Therefore, bentonite has no direct effect on the rheological behavior of the mixtures: the additives are responsible for the mechanisms of de-structuration and structure reorganization as well as the mixtures viscous and viscoelastic behavior. (author)

  12. Incorporating Natural Products, Pharmaceutical Drugs, Self-Care and Digital/Mobile Health Technologies into Molecular-Behavioral Combination Therapies for Chronic Diseases (United States)

    Bulaj, Grzegorz; Ahern, Margaret M.; Kuhn, Alexis; Judkins, Zachary S.; Bowen, Randy C.; Chen, Yizhe


    Merging pharmaceutical and digital (mobile health, mHealth) ingredients to create new therapies for chronic diseases offers unique opportunities for natural products such as omega-3 polyunsaturated fatty acids (n-3 PUFA), curcumin, resveratrol, theanine, or α-lipoic acid. These compounds, when combined with pharmaceutical drugs, show improved efficacy and safety in preclinical and clinical studies of epilepsy, neuropathic pain, osteoarthritis, depression, schizophrenia, diabetes and cancer. Their additional clinical benefits include reducing levels of TNFα and other inflammatory cytokines. We describe how pleiotropic natural products can be developed as bioactive incentives within the network pharmacology together with pharmaceutical drugs and self-care interventions. Since approximately 50% of chronically-ill patients do not take pharmaceutical drugs as prescribed, psychobehavioral incentives may appeal to patients at risk for medication non-adherence. For epilepsy, the incentive-based network therapy comprises anticonvulsant drugs, antiseizure natural products (n-3 PUFA, curcumin or/and resveratrol) coupled with disease-specific behavioral interventions delivered by mobile medical apps. The add-on combination of antiseizure natural products and mHealth supports patient empowerment and intrinsic motivation by having a choice in self-care behaviors. The incentivized therapies offer opportunities: (1) to improve clinical efficacy and safety of existing drugs, (2) to catalyze patient-centered, disease self-management and behavior-changing habits, also improving health-related quality-of-life after reaching remission, and (3) merging copyrighted mHealth software with natural products, thus establishing an intellectual property protection of medical treatments comprising the natural products existing in public domain and currently promoted as dietary supplements. Taken together, clinical research on synergies between existing drugs and pleiotropic natural products

  13. Incorporating Natural Products, Pharmaceutical Drugs, Self-Care and Digital/Mobile Health Technologies into Molecular-Behavioral Combination Therapies for Chronic Diseases. (United States)

    Bulaj, Grzegorz; Ahern, Margaret M; Kuhn, Alexis; Judkins, Zachary S; Bowen, Randy C; Chen, Yizhe


    Merging pharmaceutical and digital (mobile health, mHealth) ingredients to create new therapies for chronic diseases offers unique opportunities for natural products such as omega-3 polyunsaturated fatty acids (n-3 PUFA), curcumin, resveratrol, theanine, or α-lipoic acid. These compounds, when combined with pharmaceutical drugs, show improved efficacy and safety in preclinical and clinical studies of epilepsy, neuropathic pain, osteoarthritis, depression, schizophrenia, diabetes and cancer. Their additional clinical benefits include reducing levels of TNFα and other inflammatory cytokines. We describe how pleiotropic natural products can be developed as bioactive incentives within the network pharmacology together with pharmaceutical drugs and self-care interventions. Since approximately 50% of chronically-ill patients do not take pharmaceutical drugs as prescribed, psychobehavioral incentives may appeal to patients at risk for medication non-adherence. For epilepsy, the incentive-based network therapy comprises anticonvulsant drugs, antiseizure natural products (n-3 PUFA, curcumin or/and resveratrol) coupled with disease-specific behavioral interventions delivered by mobile medical apps. The add-on combination of antiseizure natural products and mHealth supports patient empowerment and intrinsic motivation by having a choice in self-care behaviors. The incentivized therapies offer opportunities: (1) to improve clinical efficacy and safety of existing drugs, (2) to catalyze patient-centered, disease self-management and behavior-changing habits, also improving health-related quality-of-life after reaching remission, and (3) merging copyrighted mHealth software with natural products, thus establishing an intellectual property protection of medical treatments comprising the natural products existing in public domain and currently promoted as dietary supplements. Taken together, clinical research on synergies between existing drugs and pleiotropic natural products

  14. Factors affecting mechanical (nociceptive) thresholds in piglets. (United States)

    Janczak, Andrew M; Ranheim, Birgit; Fosse, Torunn K; Hild, Sophie; Nordgreen, Janicke; Moe, Randi O; Zanella, Adroaldo J


    To evaluate the stability and repeatability of measures of mechanical (nociceptive) thresholds in piglets and to examine potentially confounding factors when using a hand held algometer. Descriptive, prospective cohort. Forty-four piglets from four litters, weighing 4.6 ± 1.0 kg (mean ± SD) at 2 weeks of age. Mechanical thresholds were measured twice on each of 2 days during the first and second week of life. Data were analyzed using a repeated measures design to test the effects of behavior prior to testing, sex, week, day within week, and repetition within day. The effect of body weight and the interaction between piglet weight and behaviour were also tested. Piglet was entered into the model as a random effect as an additional test of repeatability. The effect of repeated testing was used to test the stability of measures. Pearson correlations between repeated measures were used to test the repeatability of measures. Variance component analysis was used to describe the variability in the data. Variance component analysis indicated that piglet explained only 17% of the variance in the data. All variables in the model (behaviour prior to testing, sex, week, day within week, repetition within day, body weight, the interaction between body weight and behaviour, piglet identity) except sex had a significant effect (p testing and measures changed with repeated testing and increased with increasing piglet weight, indicating that time (age) and animal body weight should be taken into account when measuring mechanical (nociceptive) thresholds in piglets. Mechanical (nociceptive) thresholds can be used both for testing the efficacy of anaesthetics and analgesics, and for assessing hyperalgesia in chronic pain states in research and clinical settings. © 2012 The Authors. Veterinary Anaesthesia and Analgesia. © 2012 Association of Veterinary Anaesthetists and the American College of Veterinary Anesthesiologists.

  15. Metal exposure and accumulation patterns in free-range cows (Bos taurus) in a contaminated natural area: Influence of spatial and social behavior

    NARCIS (Netherlands)

    Roggeman, S.; Brink, van den N.W.; Praet, van N.; Blust, R.; Bervoets, L.


    Possible effects of spatial metal distribution, seasonal-, ecological- and ethological parameters, on the metal exposure of cows were investigated. Therefore the habitat use, vegetation selection and foraging behavior of two free ranging Galloway herds in a metal polluted nature reserve were

  16. The abundance threshold for plague as a critical percolation phenomenon. (United States)

    Davis, S; Trapman, P; Leirs, H; Begon, M; Heesterbeek, J A P


    Percolation theory is most commonly associated with the slow flow of liquid through a porous medium, with applications to the physical sciences. Epidemiological applications have been anticipated for disease systems where the host is a plant or volume of soil, and hence is fixed in space. However, no natural examples have been reported. The central question of interest in percolation theory, the possibility of an infinite connected cluster, corresponds in infectious disease to a positive probability of an epidemic. Archived records of plague (infection with Yersinia pestis) in populations of great gerbils (Rhombomys opimus) in Kazakhstan have been used to show that epizootics only occur when more than about 0.33 of the burrow systems built by the host are occupied by family groups. The underlying mechanism for this abundance threshold is unknown. Here we present evidence that it is a percolation threshold, which arises from the difference in scale between the movements that transport infectious fleas between family groups and the vast size of contiguous landscapes colonized by gerbils. Conventional theory predicts that abundance thresholds for the spread of infectious disease arise when transmission between hosts is density dependent such that the basic reproduction number (R(0)) increases with abundance, attaining 1 at the threshold. Percolation thresholds, however, are separate, spatially explicit thresholds that indicate long-range connectivity in a system and do not coincide with R(0) = 1. Abundance thresholds are the theoretical basis for attempts to manage infectious disease by reducing the abundance of susceptibles, including vaccination and the culling of wildlife. This first natural example of a percolation threshold in a disease system invites a re-appraisal of other invasion thresholds, such as those for epidemic viral infections in African lions (Panthera leo), and of other disease systems such as bovine tuberculosis (caused by Mycobacterium bovis) in

  17. Influence of humic acids on the migration behavior of radioactive and non-radioactive substances under conditions close to nature. Synthesis, radiometric determination of functional groups, complexation

    International Nuclear Information System (INIS)

    Pompe, S.; Bubner, M.; Schmeide, K.; Heise, K.H.; Bernhard, G.; Nitsche, H.


    The interaction behavior of humic acids with uranium(VI) and the influence of humic substances on the migration behavior of uranium was investigated. A main focus of this work was the synthesis of four different humic acid model substances and their characterization and comparison to the natural humic acid from Aldrich. A radiometric method for the determination of humic acid functional groups was applied in addition to conventional methods for the determination of the functionality of humic acids. The humic acid model substances show functional and structural properties comparable to natural humic acids. Modified humic acids with blocked phenolic OH were synthesized to determine the influence of phenolic OH groups on the complexation behavior of humic acids. A synthesis method for 14 C-labeled humic acids with high specific activity was developed. The complexation behavior of synthetic and natural humic acids with uranium(VI) was investigated by X-ray absorption spectroscopy, laser-induced fluorescence spectroscopy and FTIR spectroscopy. The synthetic model substances show an interaction behavior with uranium(VI) that is comparable to natural humic acids. This points to the fact that the synthetic humic acids simulate the functionality of their natural analogues very well. For the first time the influence of phenolic OH groups on the complexation behavior of humic acids was investigated by applying a modified humic acid with blocked phenolic OH groups. The formation of a uranyl hydroxy humate complex was identified by laserspectroscopic investigations of the complexation of Aldrich humic acid with uranium(VI) at pH7. The migration behavior of uranium in a sandy aquifer system rich in humic substances was investigated in column experiments. A part of uranium migrates non-retarded through the sediment, bound to humic colloids. The uranium migration behavior is strongly influenced by the kinetically controlled interaction processes of uranium with the humic colloids

  18. A semi-analytical model for the flow behavior of naturally fractured formations with multi-scale fracture networks (United States)

    Jia, Pin; Cheng, Linsong; Huang, Shijun; Wu, Yonghui


    This paper presents a semi-analytical model for the flow behavior of naturally fractured formations with multi-scale fracture networks. The model dynamically couples an analytical dual-porosity model with a numerical discrete fracture model. The small-scale fractures with the matrix are idealized as a dual-porosity continuum and an analytical flow solution is derived based on source functions in Laplace domain. The large-scale fractures are represented explicitly as the major fluid conduits and the flow is numerically modeled, also in Laplace domain. This approach allows us to include finer details of the fracture network characteristics while keeping the computational work manageable. For example, the large-scale fracture network may have complex geometry and varying conductivity, and the computations can be done at predetermined, discrete times, without any grids in the dual-porosity continuum. The validation of the semi-analytical model is demonstrated in comparison to the solution of ECLIPSE reservoir simulator. The simulation is fast, gridless and enables rapid model setup. On the basis of the model, we provide detailed analysis of the flow behavior of a horizontal production well in fractured reservoir with multi-scale fracture networks. The study has shown that the system may exhibit six flow regimes: large-scale fracture network linear flow, bilinear flow, small-scale fracture network linear flow, pseudosteady-state flow, interporosity flow and pseudoradial flow. During the first four flow periods, the large-scale fracture network behaves as if it only drains in the small-scale fracture network; that is, the effect of the matrix is negligibly small. The characteristics of the bilinear flow and the small-scale fracture network linear flow are predominantly determined by the dimensionless large-scale fracture conductivity. And low dimensionless fracture conductivity will generate large pressure drops in the large-scale fractures surrounding the wellbore. With

  19. The foraging behavior of Japanese macaques Macaca fuscata in a forested enclosure: Effects of nutrient composition, energy and its seasonal variation on the consumption of natural plant foods

    Directory of Open Access Journals (Sweden)

    M. Firoj JAMAN, Michael A. HUFFMAN, Hiroyuki TAKEMOTO


    Full Text Available In the wild, primate foraging behaviors are related to the diversity and nutritional properties of food, which are affected by seasonal variation. The goal of environmental enrichment is to stimulate captive animals to exhibit similar foraging behavior of their wild counterparts, e.g. to extend foraging time. We conducted a 12-month study on the foraging behavior of Japanese macaques in a semi-naturally forested enclosure to understand how they use both provisioned foods and naturally available plant foods and what are the nutritional criteria of their consumption of natural plants. We recorded time spent feeding on provisioned and natural plant foods and collected the plant parts ingested of their major plant food species monthly, when available. We conducted nutritional analysis (crude protein, crude lipid, neutral detergent fiber-‘NDF’, ash and calculated total non-structural carbohydrate – ‘TNC’ and total energy of those food items. Monkeys spent 47% of their feeding time foraging on natural plant species. The consumption of plant parts varied significantly across seasons. We found that leaf items were consumed in months when crude protein, crude protein-to-NDF ratio, TNC and total energy were significantly higher and NDF was significantly lower, fruit/nut items in months when crude protein and TNC were significantly higher and crude lipid content was significantly lower, and bark items in months when TNC and total energy were higher and crude lipid content was lower. This preliminary investigation showed that the forested enclosure allowed troop members to more fully express their species typical flexible behavior by challenging them to adjust their foraging behavior to seasonal changes of plant item diversity and nutritional content, also providing the possibility for individuals to nutritionally enhance their diet [Current Zoology 56 (2: 198–208, 2010].

  20. Natural history of Ctenus medius Keyserling, 1891 (Aranae, Ctenidae II: life cycle and aspects of reproductive behavior under laboratory conditions

    Directory of Open Access Journals (Sweden)



    Full Text Available Ctenus medius Keyserling, 1891 is a wandering spider common in the Brazilian Atlantic Forest. It has been the subject of few studies. Thus, this work aims to elucidate aspects of its natural history, such as the life cycle and reproductive behavior of this species, through laboratory and field observations. Two females with egg sacs were observed in the laboratory and one was observed in field (Barra Mansa, 22º32'S and 44º10'W until the emergence of the spiderlings. For observation of the immature stage development, a portion of the spiderlings from the same hatch were taken to the laboratory and watched until sexual maturity. In the field, the period between the oviposition and the emergence of spiderlings was of 36 days. The female selects a site for egg sac deposition and stays there until the spiderlings emerge. Seven days after the emergence, the female abandoned the site where the egg sac was made, concomitant to the spiderlings dispersion from observation's place and until the moment that the spiderlings started to eat. For the spiderlings kept under laboratory conditions, cannibalism was not observed in the first instars (1-4th when sufficient food was offered. Sexual maturity happened in the 14th or 15th instars, with an average of 309.2 to 344.5 days until the last/sexual molt, respectively. Until the date of sexual maturity, there was a mortality rate of 85%. This species is very fragile in captivity. This hampered deductions concerning longevity. Both females and males collected in the field were induced to mate in the laboratory. Courtship movements of males were registered, but the females did not permit the mating. These data may assist in initial biological studies of Ctenus genus and offer comparative parameters for studies of other related species.

  1. Natural history of Ctenus medius Keyserling, 1891 (Aranae, Ctenidae II: life cycle and aspects of reproductive behavior under laboratory conditions

    Directory of Open Access Journals (Sweden)


    Full Text Available Ctenus medius Keyserling, 1891 is a wandering spider common in the Brazilian Atlantic Forest. It has been the subject of few studies. Thus, this work aims to elucidate aspects of its natural history, such as the life cycle and reproductive behavior of this species, through laboratory and field observations. Two females with egg sacs were observed in the laboratory and one was observed in field (Barra Mansa, 22º32'S and 44º10'W until the emergence of the spiderlings. For observation of the immature stage development, a portion of the spiderlings from the same hatch were taken to the laboratory and watched until sexual maturity. In the field, the period between the oviposition and the emergence of spiderlings was of 36 days. The female selects a site for egg sac deposition and stays there until the spiderlings emerge. Seven days after the emergence, the female abandoned the site where the egg sac was made, concomitant to the spiderlings dispersion from observation's place and until the moment that the spiderlings started to eat. For the spiderlings kept under laboratory conditions, cannibalism was not observed in the first instars (1-4th when sufficient food was offered. Sexual maturity happened in the 14th or 15th instars, with an average of 309.2 to 344.5 days until the last/sexual molt, respectively. Until the date of sexual maturity, there was a mortality rate of 85%. This species is very fragile in captivity. This hampered deductions concerning longevity. Both females and males collected in the field were induced to mate in the laboratory. Courtship movements of males were registered, but the females did not permit the mating. These data may assist in initial biological studies of Ctenus genus and offer comparative parameters for studies of other related species.

  2. Effect of thermo-mechanical loading histories on fatigue crack growth behavior and the threshold in SUS 316 and SCM 440 steels. For prevention of high cycle thermal fatigue failures

    International Nuclear Information System (INIS)

    Okazaki, Masakazu; Muzvidziwa, Milton; Iwasaki, Akira; Kasahara, Naoto


    High cycle thermal fatigue failure of pipes induced by fluid temperature change is one of the interdisciplinary issues to be concerned for long term structural reliability of high temperature components in energy systems. In order to explore advanced life assessment methods to prevent the failure, fatigue crack propagation tests were carried out in a low alloy steel and an austenitic stainless steel under typical thermal and thermo-mechanical histories. Special attention was paid to both the effect of thermo-mechanical loading history on the fatigue crack threshold, as well as to the applicability of continuum fracture mechanics treatment to small or short cracks. It was shown experimentally that the crack-based remaining fatigue life evaluation provided more reasonable assessment than the traditional method based on the semi-empirical law in terms of 'usage factor' for high cycle thermal fatigue failure that is employed in JSME Standard, S017. The crack propagation analysis based on continuum fracture mechanics was almost successfully applied to the small fatigue cracks of which size was comparable to a few times of material grain size. It was also shown the thermo-mechanical histories introduced unique effects to the prior fatigue crack wake, resulting in occasional change in the fatigue crack threshold. (author)

  3. DOE approach to threshold quantities

    International Nuclear Information System (INIS)

    Wickham, L.E.; Kluk, A.F.; Department of Energy, Washington, DC)


    The Department of Energy (DOE) is developing the concept of threshold quantities for use in determining which waste materials must be handled as radioactive waste and which may be disposed of as nonradioactive waste at its sites. Waste above this concentration level would be managed as radioactive or mixed waste (if hazardous chemicals are present); waste below this level would be handled as sanitary waste. Ideally, the threshold must be set high enough to significantly reduce the amount of waste requiring special handling. It must also be low enough so that waste at the threshold quantity poses a very small health risk and multiple exposures to such waste would still constitute a small health risk. It should also be practical to segregate waste above or below the threshold quantity using available instrumentation. Guidance is being prepared to aid DOE sites in establishing threshold quantity values based on pathways analysis using site-specific parameters (waste stream characteristics, maximum exposed individual, population considerations, and site specific parameters such as rainfall, etc.). A guidance dose of between 0.001 to 1.0 mSv/y (0.1 to 100 mrem/y) was recommended with 0.3 mSv/y (30 mrem/y) selected as the guidance dose upon which to base calculations. Several tasks were identified, beginning with the selection of a suitable pathway model for relating dose to the concentration of radioactivity in the waste. Threshold concentrations corresponding to the guidance dose were determined for waste disposal sites at a selected humid and arid site. Finally, cost-benefit considerations at the example sites were addressed. The results of the various tasks are summarized and the relationship of this effort with related developments at other agencies discussed

  4. ‘Soglitude’- introducing a method of thinking thresholds

    Directory of Open Access Journals (Sweden)

    Tatjana Barazon


    Full Text Available ‘Soglitude’ is an invitation to acknowledge the existence of thresholds in thought. A threshold in thought designates the indetermination, the passage, the evolution of every state the world is in. The creation we add to it, and the objectivity we suppose, on the border of those two ideas lies our perceptive threshold. No state will ever be permanent, and in order to stress the temporary, fluent character of the world and our perception of it, we want to introduce a new suitable method to think change and transformation, when we acknowledge our own threshold nature. The contributions gathered in this special issue come from various disciplines: anthropology, philosophy, critical theory, film studies, political science, literature and history. The variety of these insights shows the resonance of the idea of threshold in every category of thought. We hope to enlarge the notion in further issues on physics and chemistry, as well as mathematics. The articles in this issue introduce the method of threshold thinking by showing the importance of the in-between, of the changing of perspective in their respective domain. The ‘Documents’ section named INTERSTICES, includes a selection of poems, two essays, a philosophical-artistic project called ‘infraphysique’, a performance on thresholds in the soul, and a dialogue with Israel Rosenfield. This issue presents a kaleidoscope of possible threshold thinking and hopes to initiate new ways of looking at things.For every change that occurs in reality there is a subjective counterpart in our perception and this needs to be acknowledged as such. What we name objective is reflected in our own personal perception in its own personal manner, in such a way that the objectivity of an event might altogether be questioned. The absolute point of view, the view from “nowhere”, could well be the projection that causes dogmatism. By introducing the method of thinking thresholds into a system, be it

  5. Thresholds in chemical respiratory sensitisation. (United States)

    Cochrane, Stella A; Arts, Josje H E; Ehnes, Colin; Hindle, Stuart; Hollnagel, Heli M; Poole, Alan; Suto, Hidenori; Kimber, Ian


    There is a continuing interest in determining whether it is possible to identify thresholds for chemical allergy. Here allergic sensitisation of the respiratory tract by chemicals is considered in this context. This is an important occupational health problem, being associated with rhinitis and asthma, and in addition provides toxicologists and risk assessors with a number of challenges. In common with all forms of allergic disease chemical respiratory allergy develops in two phases. In the first (induction) phase exposure to a chemical allergen (by an appropriate route of exposure) causes immunological priming and sensitisation of the respiratory tract. The second (elicitation) phase is triggered if a sensitised subject is exposed subsequently to the same chemical allergen via inhalation. A secondary immune response will be provoked in the respiratory tract resulting in inflammation and the signs and symptoms of a respiratory hypersensitivity reaction. In this article attention has focused on the identification of threshold values during the acquisition of sensitisation. Current mechanistic understanding of allergy is such that it can be assumed that the development of sensitisation (and also the elicitation of an allergic reaction) is a threshold phenomenon; there will be levels of exposure below which sensitisation will not be acquired. That is, all immune responses, including allergic sensitisation, have threshold requirement for the availability of antigen/allergen, below which a response will fail to develop. The issue addressed here is whether there are methods available or clinical/epidemiological data that permit the identification of such thresholds. This document reviews briefly relevant human studies of occupational asthma, and experimental models that have been developed (or are being developed) for the identification and characterisation of chemical respiratory allergens. The main conclusion drawn is that although there is evidence that the

  6. On computational Gestalt detection thresholds. (United States)

    Grompone von Gioi, Rafael; Jakubowicz, Jérémie


    The aim of this paper is to show some recent developments of computational Gestalt theory, as pioneered by Desolneux, Moisan and Morel. The new results allow to predict much more accurately the detection thresholds. This step is unavoidable if one wants to analyze visual detection thresholds in the light of computational Gestalt theory. The paper first recalls the main elements of computational Gestalt theory. It points out a precision issue in this theory, essentially due to the use of discrete probability distributions. It then proposes to overcome this issue by using continuous probability distributions and illustrates it on the meaningful alignment detector of Desolneux et al.

  7. Nuclear threshold effects and neutron strength function

    International Nuclear Information System (INIS)

    Hategan, Cornel; Comisel, Horia


    One proves that a Nuclear Threshold Effect is dependent, via Neutron Strength Function, on Spectroscopy of Ancestral Neutron Threshold State. The magnitude of the Nuclear Threshold Effect is proportional to the Neutron Strength Function. Evidence for relation of Nuclear Threshold Effects to Neutron Strength Functions is obtained from Isotopic Threshold Effect and Deuteron Stripping Threshold Anomaly. The empirical and computational analysis of the Isotopic Threshold Effect and of the Deuteron Stripping Threshold Anomaly demonstrate their close relationship to Neutron Strength Functions. It was established that the Nuclear Threshold Effects depend, in addition to genuine Nuclear Reaction Mechanisms, on Spectroscopy of (Ancestral) Neutron Threshold State. The magnitude of the effect is proportional to the Neutron Strength Function, in their dependence on mass number. This result constitutes also a proof that the origins of these threshold effects are Neutron Single Particle States at zero energy. (author)

  8. Fine structures in hearing thresholds and distortion product otoacoustic emissions

    DEFF Research Database (Denmark)

    Hammershøi, Dorte; Ordoñez, Rodrigo Pizarro; Torrente, Marina


    Otoacoustic emissions (OAEs) are weak sounds that can be recorded in the external ear. They are generated by the active amplification of the outer hair cells, and are by many believed to reflect the status of the most vulnerable part of the hearing better than ordinary behavioral thresholds...

  9. Weighted-noise threshold based channel estimation for OFDM ...

    Indian Academy of Sciences (India)

    Existing optimal time-domain thresholds exhibit suboptimal behavior for completely unavailable KCS environments. This is because they involve consistent estimation of one or more KCS parameters, and corresponding estimation errors introduce severe degradation in MSE performance of the CE. To overcome the MSE ...

  10. Impacts of active school design on school-time sedentary behavior and physical activity: A pilot natural experiment (United States)

    Frerichs, Leah; Sirard, John R.; Wells, Nancy M.; Myers, Beth M.; Garcia, Jeanette; Sorensen, Dina; Trowbridge, Matthew J.; Huang, Terry


    Background Children spend a significant portion of their days in sedentary behavior (SB) and on average fail to engage in adequate physical activity (PA). The school built environment may influence SB and PA, but research is limited. This natural experiment evaluated whether an elementary school designed to promote movement impacted students’ school-time SB and PA. Methods Accelerometers measured SB and PA at pre and post time-points in an intervention group who moved to the new school (n = 21) and in a comparison group experiencing no school environmental change (n = 20). Difference-in-difference (DD) analysis examined SB and PA outcomes in these groups. Measures were also collected post-intervention from an independent, grade-matched group of students in the new school (n = 21). Results As expected, maturational increases in SB were observed. However, DD analysis estimated that the intervention attenuated increase in SB by 81.2 ± 11.4 minutes/day (p<0.001), controlling for time in moderate to vigorous physical activity (MVPA). The intervention was also estimated to increase daily number of breaks from SB by 23.4 ± 2.6 (p < .001) and to increase light physical activity (LPA) by 67.7 ± 10.7 minutes/day (p<0.001). However, the intervention decreased MVPA by 10.3 ± 2.3 minutes/day (p<0.001). Results of grade-matched independent samples analysis were similar, with students in the new vs. old school spending 90.5 ± 16.1 fewer minutes/day in SB, taking 21.1 ± 2.7 more breaks from SB (p<0.001), and spending 64.5 ± 14.8 more minutes in LPA (p<0.001), controlling for time in MVPA. Students in the new school spent 13.1 ± 2.7 fewer minutes in MVPA (p<0.001) than their counterparts in the old school. Conclusions This pilot study found that active school design had beneficial effects on SB and LPA, but not on MVPA. Mixed results point to a need for active classroom design strategies to mitigate SB, and quick access from classrooms to areas permissive of high

  11. Thresholds models of technological transitions

    NARCIS (Netherlands)

    Zeppini, P.; Frenken, K.; Kupers, R.


    We present a systematic review of seven threshold models of technological transitions from physics, biology, economics and sociology. The very same phenomenon of a technological transition can be explained by very different logics, ranging from economic explanations based on price, performance and

  12. Risk thresholds for alcohol consumption

    DEFF Research Database (Denmark)

    Wood, Angela M; Kaptoge, Stephen; Butterworth, Adam S


    BACKGROUND: Low-risk limits recommended for alcohol consumption vary substantially across different national guidelines. To define thresholds associated with lowest risk for all-cause mortality and cardiovascular disease, we studied individual-participant data from 599 912 current drinkers withou...

  13. Weights of Exact Threshold Functions

    DEFF Research Database (Denmark)

    Babai, László; Hansen, Kristoffer Arnsfelt; Podolskii, Vladimir V.


    We consider Boolean exact threshold functions defined by linear equations, and in general degree d polynomials. We give upper and lower bounds on the maximum magnitude (absolute value) of the coefficients required to represent such functions. These bounds are very close and in the linear case in ...... leave a substantial gap, a challenge for future work....

  14. Threshold quantities for helminth infections

    NARCIS (Netherlands)

    Heesterbeek, J.A.P.; Roberts, M.G.


    For parasites with a clearly defined life-cycle we give threshold quantities that determine the stability of the parasite-free steady state for autonomous and periodic deterministic systems formulated in terms of mean parasite burdens. We discuss the biological interpretations of the quantities, how

  15. Percolation Threshold Parameters of Fluids

    Czech Academy of Sciences Publication Activity Database

    Škvor, J.; Nezbeda, Ivo


    Roč. 79, č. 4 (2009), 041141-041147 ISSN 1539-3755 Institutional research plan: CEZ:AV0Z40720504 Keywords : percolation threshold * universality * infinite cluster Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.400, year: 2009

  16. Crossing Thresholds in Academic Reading (United States)

    Abbott, Rob


    This paper looks at the conceptual thresholds in relation to academic reading which might be crossed by undergraduate English Literature students. It is part of a wider study following 16 students through three years of undergraduate study. It uses theoretical ideas from Bakhtin and Foucault to analyse interviews with English lecturers. It…

  17. The Effect of Having Classmates with Emotional and Behavioral Disorders and the Protective Nature of Peer Gender (United States)

    Gottfried, Michael A.; Harven, Aletha


    The authors explored how classroom gender composition moderated the relationship between having classmates with emotional and behavioral disorders (EBD) and peers' academic achievement in both kindergarten and Grade 1 classrooms. Given the behavioral and social-cognitive styles of girls, it was hypothesized that classrooms with a higher percentage…

  18. Quantifying ecological thresholds from response surfaces (United States)

    Heather E. Lintz; Bruce McCune; Andrew N. Gray; Katherine A. McCulloh


    Ecological thresholds are abrupt changes of ecological state. While an ecological threshold is a widely accepted concept, most empirical methods detect them in time or across geographic space. Although useful, these approaches do not quantify the direct drivers of threshold response. Causal understanding of thresholds detected empirically requires their investigation...

  19. Optimal threshold estimation for binary classifiers using game theory. (United States)

    Sanchez, Ignacio Enrique


    Many bioinformatics algorithms can be understood as binary classifiers. They are usually compared using the area under the receiver operating characteristic ( ROC ) curve. On the other hand, choosing the best threshold for practical use is a complex task, due to uncertain and context-dependent skews in the abundance of positives in nature and in the yields/costs for correct/incorrect classification. We argue that considering a classifier as a player in a zero-sum game allows us to use the minimax principle from game theory to determine the optimal operating point. The proposed classifier threshold corresponds to the intersection between the ROC curve and the descending diagonal in ROC space and yields a minimax accuracy of 1-FPR. Our proposal can be readily implemented in practice, and reveals that the empirical condition for threshold estimation of "specificity equals sensitivity" maximizes robustness against uncertainties in the abundance of positives in nature and classification costs.

  20. Stable, tunable, quasimonoenergetic electron beams produced in a laser wakefield near the threshold for self-injection

    Directory of Open Access Journals (Sweden)

    S. Banerjee


    Full Text Available Stable operation of a laser-plasma accelerator near the threshold for electron self-injection in the blowout regime has been demonstrated with 25–60 TW, 30 fs laser pulses focused into a 3–4 millimeter length gas jet. Nearly Gaussian shape and high nanosecond contrast of the focused pulse appear to be critically important for controllable, tunable generation of 250–430 MeV electron bunches with a low-energy spread, ∼10  pC charge, a few-mrad divergence and pointing stability, and a vanishingly small low-energy background. The physical nature of the near-threshold behavior is examined using three-dimensional particle-in-cell simulations. Simulations indicate that properly locating the nonlinear focus of the laser pulse within the plasma suppresses continuous injection, thus reducing the low-energy tail of the electron beam.

  1. On the nature of directed behavior to drug-associated light cues in rhesus monkeys (Macaca mulatta). (United States)

    Reilly, Mark P; Berndt, Sonja I; Woods, James H


    The present study investigated the role of drug-paired stimuli in controlling the behavior of rhesus monkeys. Systematic observations were made with nine monkeys who had a history of drug self-administration; they had been lever pressing to produce intravenous infusions of various drugs. These observations revealed that the stimulus light co-occurring with drug infusion produced robust and cue-directed behavior such as orienting, touching and biting. Experiment 1 showed that this light-directed behavior would occur in naïve monkeys exposed to a Pavlovian pairing procedure. Four monkeys were given response-independent injections of cocaine. In two monkeys, a red light preceded cocaine injections by 5 s, and a green light co-occurred with the 5-s cocaine injections. In the other two monkeys, the light presentations and cocaine injections occurred independently. Light-directed behavior occurred in all four monkeys within the first couple of trials and at high levels but decreased across sessions. The cocaine-paired stimulus maintained behavior longer and at higher levels than the uncorrelated stimuli. Furthermore, light-directed behavior was not maintained when cocaine was replaced with saline. Light-directed behavior did not occur in the absence of the lights. When these monkeys were subsequently trained to lever press for cocaine, light-directed behavior increased to levels higher than previously observed. Behavior directed towards drug-paired stimuli is robust, reliable and multiply determined; the mechanisms underlying this activity likely include Pavlovian conditioning, stimulus novelty, habituation and operant conditioning.

  2. Self-adjusting threshold mechanism for pixel detectors (United States)

    Heim, Timon; Garcia-Sciveres, Maurice


    Readout chips of hybrid pixel detectors use a low power amplifier and threshold discrimination to process charge deposited in semiconductor sensors. Due to transistor mismatch each pixel circuit needs to be calibrated individually to achieve response uniformity. Traditionally this is addressed by programmable threshold trimming in each pixel, but requires robustness against radiation effects, temperature, and time. In this paper a self-adjusting threshold mechanism is presented, which corrects the threshold for both spatial inequality and time variation and maintains a constant response. It exploits the electrical noise as relative measure for the threshold and automatically adjust the threshold of each pixel to always achieve a uniform frequency of noise hits. A digital implementation of the method in the form of an up/down counter and combinatorial logic filter is presented. The behavior of this circuit has been simulated to evaluate its performance and compare it to traditional calibration results. The simulation results show that this mechanism can perform equally well, but eliminates instability over time and is immune to single event upsets.

  3. Using the theory of planned behavior to identify key beliefs underlying Brazilian cattle farmers' intention to use improved natural grassland

    NARCIS (Netherlands)

    Rossi Borges, Joao; Tauer, Loren Willian; Oude Lansink, Alfons


    In biome Pampa, Brazil, cattle farmers have managed the natural grasslands using practices that result in overgrazing, low productivity and low farm income. In addition, farmers in the region converted natural grasslands from beef production to more profitable activities, such as cash crops. This

  4. Polyaromatic hydrocarbons (PAHs) sorption behavior unaffected by the presence of multi-walled carbon nanotubes (MWNTs) in a natural soil system. (United States)

    Li, Shibin; Anderson, Todd A; Green, Micah J; Maul, Jonathan D; Cañas-Carrell, Jaclyn E


    The batch equilibrium approach was used to examine the influence of multi-walled carbon nanotubes (MWNTs) on the sorption behaviors of polyaromatic hydrocarbons (PAHs) in soil. To the knowledge of the authors, this is the first study of PAH sorption to MWNTs in real natural soil systems. The sorption behavior of three PAHs (naphthalene, fluorene, and phenanthrene) in the presence of commercially available MWNTs in two natural soils (a sandy loam and a silt loam) and Ottawa sand was evaluated. Adsorption of PAHs by MWNTs in this study was three orders of magnitude higher than that of natural soils. Sorption coefficients of PAHs (Kd and Koc) were unchanged in the presence of 2 mg g(-1) MWNTs in soil (p > 0.05). A micro-mechanics approach, termed 'the rule of mixtures' was used for predicting PAH sorption behaviors in mixtures based on sorption coefficients derived from single sorbents. The equation, KT = KMα + KN(1 - α) (K, sorption coefficients, Kd or Koc), predicted sorption coefficients in a mixture based on mixture component sorption coefficients and mass fractions. Data presented in this study could be used to fill data gaps related to the environmental fate of carbon nanotubes in soil.

  5. Cochlear neuropathy and the coding of supra-threshold sound. (United States)

    Bharadwaj, Hari M; Verhulst, Sarah; Shaheen, Luke; Liberman, M Charles; Shinn-Cunningham, Barbara G


    Many listeners with hearing thresholds within the clinically normal range nonetheless complain of difficulty hearing in everyday settings and understanding speech in noise. Converging evidence from human and animal studies points to one potential source of such difficulties: differences in the fidelity with which supra-threshold sound is encoded in the early portions of the auditory pathway. Measures of auditory subcortical steady-state responses (SSSRs) in humans and animals support the idea that the temporal precision of the early auditory representation can be poor even when hearing thresholds are normal. In humans with normal hearing thresholds (NHTs), paradigms that require listeners to make use of the detailed spectro-temporal structure of supra-threshold sound, such as selective attention and discrimination of frequency modulation (FM), reveal individual differences that correlate with subcortical temporal coding precision. Animal studies show that noise exposure and aging can cause a loss of a large percentage of auditory nerve fibers (ANFs) without any significant change in measured audiograms. Here, we argue that cochlear neuropathy may reduce encoding precision of supra-threshold sound, and that this manifests both behaviorally and in SSSRs in humans. Furthermore, recent studies suggest that noise-induced neuropathy may be selective for higher-threshold, lower-spontaneous-rate nerve fibers. Based on our hypothesis, we suggest some approaches that may yield particularly sensitive, objective measures of supra-threshold coding deficits that arise due to neuropathy. Finally, we comment on the potential clinical significance of these ideas and identify areas for future investigation.

  6. High-order above-threshold dissociation of molecules (United States)

    Lu, Peifen; Wang, Junping; Li, Hui; Lin, Kang; Gong, Xiaochun; Song, Qiying; Ji, Qinying; Zhang, Wenbin; Ma, Junyang; Li, Hanxiao; Zeng, Heping; He, Feng; Wu, Jian


    Electrons bound to atoms or molecules can simultaneously absorb multiple photons via the above-threshold ionization featured with discrete peaks in the photoelectron spectrum on account of the quantized nature of the light energy. Analogously, the above-threshold dissociation of molecules has been proposed to address the multiple-photon energy deposition in the nuclei of molecules. In this case, nuclear energy spectra consisting of photon-energy spaced peaks exceeding the binding energy of the molecular bond are predicted. Although the observation of such phenomena is difficult, this scenario is nevertheless logical and is based on the fundamental laws. Here, we report conclusive experimental observation of high-order above-threshold dissociation of H2 in strong laser fields where the tunneling-ionized electron transfers the absorbed multiphoton energy, which is above the ionization threshold to the nuclei via the field-driven inelastic rescattering. Our results provide an unambiguous evidence that the electron and nuclei of a molecule as a whole absorb multiple photons, and thus above-threshold ionization and above-threshold dissociation must appear simultaneously, which is the cornerstone of the nowadays strong-field molecular physics.

  7. Elicitation threshold of cobalt chloride

    DEFF Research Database (Denmark)

    Fischer, Louise A; Johansen, Jeanne D; Voelund, Aage


    BACKGROUND: Cobalt is a strong skin sensitizer (grade 5 of 5 in the guinea-pig maximization test) that is used in various industrial and consumer applications. To prevent sensitization to cobalt and elicitation of allergic cobalt dermatitis, information about the elicitation threshold level...... of cobalt is important. OBJECTIVE: To identify the dermatitis elicitation threshold levels in cobalt-allergic individuals. MATERIALS AND METHODS: Published patch test dose-response studies were reviewed to determine the elicitation dose (ED) levels in dermatitis patients with a previous positive patch test...... reaction to cobalt. A logistic dose-response model was applied to data collected from the published literature to estimate ED values. The 95% confidence interval (CI) for the ratio of mean doses that can elicit a reaction in 10% (ED(10)) of a population was calculated with Fieller's method. RESULTS...

  8. Realistic Realizations Of Threshold Circuits (United States)

    Razavi, Hassan M.


    Threshold logic, in which each input is weighted, has many theoretical advantages over the standard gate realization, such as reducing the number of gates, interconnections, and power dissipation. However, because of the difficult synthesis procedure and complicated circuit implementation, their use in the design of digital systems is almost nonexistant. In this study, three methods of NMOS realizations are discussed, and their advantages and shortcomings are explored. Also, the possibility of using the methods to realize multi-valued logic is examined.

  9. Root finding with threshold circuits

    Czech Academy of Sciences Publication Activity Database

    Jeřábek, Emil


    Roč. 462, Nov 30 (2012), s. 59-69 ISSN 0304-3975 R&D Projects: GA AV ČR IAA100190902; GA MŠk(CZ) 1M0545 Institutional support: RVO:67985840 Keywords : root finding * threshold circuit * power series Subject RIV: BA - General Mathematics Impact factor: 0.489, year: 2012

  10. A soft computing approach for prediction of P- ρ-T behavior of natural gas using adaptive neuro-fuzzy inference system

    Directory of Open Access Journals (Sweden)

    Amir Hossein Saeedi Dehaghani


    Full Text Available Density is an important property of natural gas required for the design of gas processing and reservoir simulation. Due to expensive measurement of density, industry tends to predict gas density through an EOS. However, all EOS are associated with uncertainties, especially at high-pressure conditions. Also, using sophisticated EOS in commercial software renders simulation highly time-consuming. This work aims to evaluate performance of adaptive neuro-fuzzy inference system (ANFIS as a widely-accepted intelligent model for prediction of P-ρ-T behavior of natural gas. Using experimental data reported in the literature, our inference system was trained with 95 data of natural gas densities in the temperature range of (250–450K and pressures up to 150 MPa. Additionally, prediction by ANFIS was compared with those of AGA8 and GERG04 which both are leading industrial EOS for calculation of natural gas density. It was observed that ANFIS predicts natural gas density with AARD% of 1.704; and is able to estimate gas density as accurate as sophisticated EOS. The proposed model is applicable for predicting gas density in the range of (250–450 K, (10–150 MPa and also for sweet gases, i.e., containing a low concentration of N2 and CO2. Keywords: Natural gas, Density, Fuzzy inference system, Intelligent modelling, Equation of state

  11. Behavioral and physiological responses to subgroup size and number of people in howler monkeys inhabiting a forest fragment used for nature-based tourism. (United States)

    Aguilar-Melo, Adriana R; Andresen, Ellen; Cristóbal-Azkarate, Jurgi; Arroyo-Rodríguez, Victor; Chavira, Roberto; Schondube, Jorge; Serio-Silva, Juan Carlos; Cuarón, Alfredo D


    Animals' responses to potentially threatening factors can provide important information for their conservation. Group size and human presence are potentially threatening factors to primates inhabiting small reserves used for recreation. We tested these hypotheses by evaluating behavioral and physiological responses in two groups of mantled howler monkeys (Alouatta palliata mexicana) at the "Centro Ecológico y Recreativo El Zapotal", a recreational forest reserve and zoo located in the Mexican state of Chiapas. Both groups presented fission-fusion dynamics, splitting into foraging subgroups which varied in size among, but not within days. Neither subgroup size nor number of people had an effect on fecal cortisol. Out of 16 behavioral response variables tested, the studied factors had effects on six: four were affected by subgroup size and two were affected by number of people. With increasing subgroup size, monkeys increased daily path lengths, rested less, increased foraging effort, and used more plant individuals for feeding. As the number of people increased, monkeys spent more time in lower-quality habitat, and less time engaged in social interactions. Although fecal cortisol levels were not affected by the factors studied, one of the monkey groups had almost twice the level of cortisol compared to the other group. The group with higher cortisol levels also spent significantly more time in the lower-quality habitat, compared to the other group. Our results suggest that particular behavioral adjustments might allow howler monkeys at El Zapotal to avoid physiological stress due to subgroup size and number of people. However, the fact that one of the monkey groups is showing increased cortisol levels may be interpreted as a warning sign, indicating that an adjustment threshold is being reached, at least for part of the howler monkey population in this forest fragment. © 2013 Wiley Periodicals, Inc.

  12. Noisy-threshold control of cell death

    Directory of Open Access Journals (Sweden)

    Vilar Jose MG


    Full Text Available Abstract Background Cellular responses to death-promoting stimuli typically proceed through a differentiated multistage process, involving a lag phase, extensive death, and potential adaptation. Deregulation of this chain of events is at the root of many diseases. Improper adaptation is particularly important because it allows cell sub-populations to survive even in the continuous presence of death conditions, which results, among others, in the eventual failure of many targeted anticancer therapies. Results Here, I show that these typical responses arise naturally from the interplay of intracellular variability with a threshold-based control mechanism that detects cellular changes in addition to just the cellular state itself. Implementation of this mechanism in a quantitative model for T-cell apoptosis, a prototypical example of programmed cell death, captures with exceptional accuracy experimental observations for different expression levels of the oncogene Bcl-xL and directly links adaptation with noise in an ATP threshold below which cells die. Conclusions These results indicate that oncogenes like Bcl-xL, besides regulating absolute death values, can have a novel role as active controllers of cell-cell variability and the extent of adaptation.

  13. Alteration of rhyolitic (volcanic) glasses in natural Bolivian salt lakes. - Natural analogue for the behavior of radioactive waste glasses in rock salt repositories

    International Nuclear Information System (INIS)

    Abdelouas, A.


    Alteration experiments with the R7T7 glass in three salt brines, saturated respectively in MgCl 2 , MgCl 2 -CaCl 2 and NaCl, showed that the solubilities of most radionuclides are controlled by the secondary phases. Nd, La, and Pr are trapped in powellite, Ce in cerianite, U in coffinite, and Sr is partially immobilized in barite. There is a good similarity between the secondary phases formed experimentally on volcanic glasses and the R7T7 glass altered in MgCl 2 CaCl 2 -saturated brine (formation of hydrotalcite and chlorite-serpentine at short-term and saponite at long-term). These results support the use of volcanic glasses alteration patterns in Mg-rich solutions (seawater, brines) to understand the long-term behavior of nuclear waste glasses and to evaluate the stability of the secondary phases. The study of the sediments of Uyuni (Bolivia) showed that the corrosion rate of the rhyolitic glass in brines at 10 C is 12 to 30 time lower than those of rhyolitic glasses altered in high dilute conditions. The neoformed phases in the sediments are: Smectite, alunite, pyrite, barite, celestite and cerianite. The low alteration rate of rhyolitic glasses in brines and the formation of secondary phases such as smectite, barite and cerianite (also formed during the experimental alteration of the R7T7 glass), permit us to expect the low alteration of nuclear waste glasses at long-term in brines and the trapping of certain radionuclides in secondary phases. (orig.) [de

  14. Color difference thresholds in dentistry. (United States)

    Paravina, Rade D; Ghinea, Razvan; Herrera, Luis J; Bona, Alvaro D; Igiel, Christopher; Linninger, Mercedes; Sakai, Maiko; Takahashi, Hidekazu; Tashkandi, Esam; Perez, Maria del Mar


    The aim of this prospective multicenter study was to determine 50:50% perceptibility threshold (PT) and 50:50% acceptability threshold (AT) of dental ceramic under simulated clinical settings. The spectral radiance of 63 monochromatic ceramic specimens was determined using a non-contact spectroradiometer. A total of 60 specimen pairs, divided into 3 sets of 20 specimen pairs (medium to light shades, medium to dark shades, and dark shades), were selected for psychophysical experiment. The coordinating center and seven research sites obtained the Institutional Review Board (IRB) approvals prior the beginning of the experiment. Each research site had 25 observers, divided into five groups of five observers: dentists-D, dental students-S, dental auxiliaries-A, dental technicians-T, and lay persons-L. There were 35 observers per group (five observers per group at each site ×7 sites), for a total of 175 observers. Visual color comparisons were performed using a viewing booth. Takagi-Sugeno-Kang (TSK) fuzzy approximation was used for fitting the data points. The 50:50% PT and 50:50% AT were determined in CIELAB and CIEDE2000. The t-test was used to evaluate the statistical significance in thresholds differences. The CIELAB 50:50% PT was ΔEab  = 1.2, whereas 50:50% AT was ΔEab  = 2.7. Corresponding CIEDE2000 (ΔE00 ) values were 0.8 and 1.8, respectively. 50:50% PT by the observer group revealed differences among groups D, A, T, and L as compared with 50:50% PT for all observers. The 50:50% AT for all observers was statistically different than 50:50% AT in groups T and L. A 50:50% perceptibility and ATs were significantly different. The same is true for differences between two color difference formulas ΔE00 /ΔEab . Observer groups and sites showed high level of statistical difference in all thresholds. Visual color difference thresholds can serve as a quality control tool to guide the selection of esthetic dental materials, evaluate clinical performance, and

  15. Level reduction and the quantum threshold theorem (United States)

    Aliferis, Panagiotis (Panos)

    Computers have led society to the information age revolutionizing central aspects of our lives from production and communication to education and entertainment. There exist, however, important problems which are intractable with the computers available today and, experience teaches us, will remain so even with the more advanced computers we can envision for tomorrow.Quantum computers promise speedups to some of these important but classically intractable problems. Simulating physical systems, a problem of interest in a diverse range of areas from testing physical theories to understanding chemical reactions, and solving number factoring, a problem at the basis of cryptographic protocols that are used widely today on the internet, are examples of applications for which quantum computers, when built, will offer a great advantage over what is possible with classical computer technology.The construction of a quantum computer of sufficient scale to solve interesting problems is, however, especially challenging. The reason for this is that, by its very nature, operating a quantum computer will require the coherent control of the quantum state of a very large number of particles. Fortunately, the theory of quantum error correction and fault-tolerant quantum computation gives us confidence that such quantum states can be created, can be stored in memory and can also be manipulated provided the quantum computer can be isolated to a sufficient degree from sources of noise.One of the central results in the theory of fault-tolerant quantum computation, the quantum threshold theorem shows that a noisy quantum computer can accurately and efficiently simulate any ideal quantum computation provided that noise is weakly correlated and its strength is below a critical value known as the quantum accuracy threshold. This thesis provides a simpler and more transparent non-inductive proof of this theorem based on the concept of level reduction. This concept is also used in proving the

  16. Comparing Various Type of Natural Fibers as Filler in TPU: Mechanical Properties, Morphological and Oil Absorption Behavior

    Directory of Open Access Journals (Sweden)

    Ahad Nor Azwin


    Full Text Available The idea of using natural fibers as filler in various polymers has been extensively studied. Various types of natural fibers and polymers have been identified and it can be varied according to the particular application and the two main composite materials will have advantages and disadvantages of each. However, natural fibers are usually selected as filler because it is readily available and environmentally friendly, inexpensive, non-toxic, biodegradable and still have good characteristics for a variety of uses. In this study, four types of natural fiber have been used which; coconut shell, coconut fiber, corn cob, and pineapple skin, as fillers in thermoplastic polyurethane (TPU. The mixing process conducted through melt mixing techniques. The percentage of TPU and natural fibers are 100/0, 95/5, 90/10 and 85/15. Different type of fiber will affect the mechanical properties of the composites and have been studied through tensile testing. It showed that the result for pineapple fiber at 5% was the highest and can also be related to the characterizations of this composite that have been studied via the SEM morphology. Swelling testing is also having been done to prove the absorbency ability by natural fiber composites in cooking oil and engine oil. Then it concluded that the pineapple fiber absorbed large amount of both oil compared to others.

  17. The threshold expansion of the 2-loop sunrise self-mass master amplitudes

    International Nuclear Information System (INIS)

    Caffo, M.; Czyz, H.; Remiddi, E.


    The threshold behavior of the master amplitudes for two loop sunrise self-mass graph is studied by solving the system of differential equations, which they satisfy. The expansion at the threshold of the master amplitudes is obtained analytically for arbitrary masses

  18. Gaze Behavior in a Natural Environment with a Task-Relevant Distractor: How the Presence of a Goalkeeper Distracts the Penalty Taker

    Directory of Open Access Journals (Sweden)

    Johannes Kurz


    Full Text Available Gaze behavior in natural scenes has been shown to be influenced not only by top–down factors such as task demands and action goals but also by bottom–up factors such as stimulus salience and scene context. Whereas gaze behavior in the context of static pictures emphasizes spatial accuracy, gazing in natural scenes seems to rely more on where to direct the gaze involving both anticipative components and an evaluation of ongoing actions. Not much is known about gaze behavior in far-aiming tasks in which multiple task-relevant targets and distractors compete for the allocation of visual attention via gaze. In the present study, we examined gaze behavior in the far-aiming task of taking a soccer penalty. This task contains a proximal target, the ball; a distal target, an empty location within the goal; and a salient distractor, the goalkeeper. Our aim was to investigate where participants direct their gaze in a natural environment with multiple potential fixation targets that differ in task relevance and salience. Results showed that the early phase of the run-up seems to be driven by both the salience of the stimulus setting and the need to perform a spatial calibration of the environment. The late run-up, in contrast, seems to be controlled by attentional demands of the task with penalty takers having habitualized a visual routine that is not disrupted by external influences (e.g., the goalkeeper. In addition, when trying to shoot a ball as accurately as possible, penalty takers directed their gaze toward the ball in order to achieve optimal foot-ball contact. These results indicate that whether gaze is driven by salience of the stimulus setting or by attentional demands depends on the phase of the actual task.

  19. Voting on Thresholds for Public Goods

    DEFF Research Database (Denmark)

    Rauchdobler, Julian; Sausgruber, Rupert; Tyran, Jean-Robert

    Introducing a threshold in the sense of a minimal project size transforms a public goods game with an inefficient equilibrium into a coordination game with a set of Pareto-superior equilibria. Thresholds may therefore improve efficiency in the voluntary provision of public goods. In our one......-shot experiment, we find that coordination often fails and exogenously imposed thresholds are ineffective at best and often counter-productive. This holds under a range of threshold levels and refund rates. We test if thresholds perform better if they are endogenously chosen, i.e. if a threshold is approved...

  20. Some statements on the detection threshold of radioactivity measuring instruments

    International Nuclear Information System (INIS)

    Berger, H.U.


    It is shown that, from the point of view of practical radiation protection, the concept of 'detection threshold' is misleading if, when determining the detection threshold, errors of 2nd kind are not fully taken into account. An 'error of 2nd kind' is defined to be the incorrect assumption of 'no contamination' on the basis of a single measuring result which showed a net counting rate below the incertainty of the background counting rate. These errors are caused by the fact that, due to the statistical nature of the radiation process, the net counting rate of a sample, measured just once, may be below its expectation value. (orig.) [de

  1. Determination of Foraging Thresholds and Effects of Application on Energetic Carrying Capacity for Waterfowl (United States)


    Energetic carrying capacity of habitats for wildlife is a fundamental concept used to better understand population ecology and prioritize conservation efforts. However, carrying capacity can be difficult to estimate accurately and simplified models often depend on many assumptions and few estimated parameters. We demonstrate the complex nature of parameterizing energetic carrying capacity models and use an experimental approach to describe a necessary parameter, a foraging threshold (i.e., density of food at which animals no longer can efficiently forage and acquire energy), for a guild of migratory birds. We created foraging patches with different fixed prey densities and monitored the numerical and behavioral responses of waterfowl (Anatidae) and depletion of foods during winter. Dabbling ducks (Anatini) fed extensively in plots and all initial densities of supplemented seed were rapidly reduced to 10 kg/ha and other natural seeds and tubers combined to 170 kg/ha, despite different starting densities. However, ducks did not abandon or stop foraging in wetlands when seed reduction ceased approximately two weeks into the winter-long experiment nor did they consistently distribute according to ideal-free predictions during this period. Dabbling duck use of experimental plots was not related to initial seed density, and residual seed and tuber densities varied among plant taxa and wetlands but not plots. Herein, we reached several conclusions: 1) foraging effort and numerical responses of dabbling ducks in winter were likely influenced by factors other than total food densities (e.g., predation risk, opportunity costs, forager condition), 2) foraging thresholds may vary among foraging locations, and 3) the numerical response of dabbling ducks may be an inconsistent predictor of habitat quality relative to seed and tuber density. We describe implications on habitat conservation objectives of using different foraging thresholds in energetic carrying capacity models and

  2. Preparation and wear behavior of polymer matrix composites with an interpenetrating network structure derived from natural sponge

    International Nuclear Information System (INIS)

    Wang Tianchi; Zhou Tianle; Xiong Dangsheng


    Natural sponge was used as a template to produce carbon/epoxy resin and (carbon+silicon carbide)/epoxy resin composites with interpenetrating network structures. Carbon with a network structure was first obtained by pyrolysis of the natural sponge. The composites were then obtained by injecting epoxy resin and silicone resin into the carbon. Their microstructures and wear properties were analyzed. The results show that the natural structure of sponge controlled the interpenetrating network structures of the composites. The netlike carbon in the composites reduced the wear rate of the epoxy resin. Compared with the carbon/epoxy resin composite, the (carbon+silicon carbide)/epoxy resin composite shows better wear resistance.

  3. Optimizing Systems of Threshold Detection Sensors

    National Research Council Canada - National Science Library

    Banschbach, David C


    .... Below the threshold all signals are ignored. We develop a mathematical model for setting individual sensor thresholds to obtain optimal probability of detecting a significant event, given a limit on the total number of false positives allowed...

  4. Nuclear thermodynamics below particle threshold

    International Nuclear Information System (INIS)

    Schiller, A.; Agvaanluvsan, U.; Algin, E.; Bagheri, A.; Chankova, R.; Guttormsen, M.; Hjorth-Jensen, M.; Rekstad, J.; Siem, S.; Sunde, A. C.; Voinov, A.


    From a starting point of experimentally measured nuclear level densities, we discuss thermodynamical properties of nuclei below the particle emission threshold. Since nuclei are essentially mesoscopic systems, a straightforward generalization of macroscopic ensemble theory often yields unphysical results. A careful critique of traditional thermodynamical concepts reveals problems commonly encountered in mesoscopic systems. One of which is the fact that microcanonical and canonical ensemble theory yield different results, another concerns the introduction of temperature for small, closed systems. Finally, the concept of phase transitions is investigated for mesoscopic systems

  5. The Precision of eCAP Thresholds Derived From Amplitude Growth Functions. (United States)

    Biesheuvel, Jan Dirk; Briaire, Jeroen J; Frijns, Johan H M


    An amplitude growth function (AGF) shows the amplitude of an electrically evoked compound action potential (eCAP) as a function of the stimulation current. AGFs can be used to derive the eCAP threshold, which represents the minimum amount of current needed to elicit a measurable eCAP. eCAP thresholds have been widely used clinically to, for example, assist with sound processor programming. However, no eCAP precision has been included to date. The aim of this study was to investigate the precision of eCAP thresholds and determine whether they are precise enough for clinical use. The study is retrospective, and the data comprised 826 AGFs, intraoperatively measured in 111 patients implanted with a HiRes90K cochlear implant (Advanced Bionics). For each AGF, the eCAP threshold was determined using two commonly used methods: linear extrapolation (LE) toward the x axis and detection of the last visible (LV) eCAP. Subsequently, the threshold confidence interval (TCI) of each eCAP threshold was calculated to serve as a metric for precision, whereby a larger TCI means a lower precision or reliability. Additionally, the eCAP thresholds results were compared with most recent behavioral fitting thresholds (T profile) to put the eCAP threshold analysis in clinical context. Thereby, the association between eCAP and behavioral thresholds was calculated, both for all subjects together (group analysis) and, in contrast to previous studies, within individual subjects. Our data show that the TCIs were larger with the LE method than with the LV method. The eCAP thresholds estimated by the LE method were systematically smaller than those estimated by the LV method, while the LE thresholds with the smallest TCIs correlated best with the LV thresholds. Correlation analysis between eCAP and behavioral thresholds revealed correlation coefficients of r = 0.44 and r = 0.54 for the group analysis of LE and LV thresholds, respectively. Within individual subjects, however, the correlation

  6. Explaining Emotional Attachment to a Protected Area by Visitors' Perceived Importance of Seeing Wildlife, Behavioral Connections with Nature and Sociodemographics

    NARCIS (Netherlands)

    Huigen, Paulus P.P.; Haartsen, Tialda; Folmer, Akke


    Recently, the interest in understanding emotional bonds with protected nature areas has been growing. The role of wildlife in emotional bonds with places has until now not been the focus of many studies. The aim of our paper is to explore relations between the perceived importance of seeing wildlife

  7. Flow visualization of bubble behavior under two-phase natural circulation flow conditions using high speed digital camera

    Energy Technology Data Exchange (ETDEWEB)

    Lemos, Wanderley F.; Su, Jian, E-mail:, E-mail: [Coordenacao dos Programas de Pos-Graduacao em Engenharia (COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Programa de Engenharia Nuclear; Faccini, Jose L.H., E-mail: [Instituto de Engenharia Nuclear (IEN/CNEN-RJ), Rio de Janeiro, RJ (Brazil). Lab. de Termo-Hidraulica Experimental


    The The present work aims at identifying flow patterns and measuring interfacial parameters in two-phase natural circulation by using visualization technique with high-speed digital camera. The experiments were conducted in the Natural Circulation Circuit (CCN), installed at Nuclear Engineering Institute/CNEN. The thermo-hydraulic circuit comprises heater, heat exchanger, expansion tank, the pressure relief valve and pipes to interconnect the components. A glass tube is installed at the midpoint of the riser connected to the heater outlet. The natural circulation circuit is complemented by acquisition system of values of temperatures, flow and graphic interface. The instrumentation has thermocouples, volumetric flow meter, rotameter and high-speed digital camera. The experimental study is performed through analysis of information from measurements of temperatures at strategic points along the hydraulic circuit, besides natural circulation flow rates. The comparisons between analytical and experimental values are validated by viewing, recording and processing of the images for the flows patterns. Variables involved in the process of identification of flow regimes, dimensionless parameters, the phase velocity of the flow, initial boiling point, the phenomenon of 'flashing' pre-slug flow type were obtained experimentally. (author)

  8. Methyl eugenol: its occurrence, distribution, and role in nature, especially in relation to insect behavior and pollination. (United States)

    Tan, Keng Hong; Nishida, Ritsuo


    This review discusses the occurrence and distribution (within a plant) of methyl eugenol in different plant species (> 450) from 80 families spanning many plant orders, as well as various roles this chemical plays in nature, especially in the interactions between tephritid fruit flies and plants.

  9. Methyl Eugenol: Its Occurrence, Distribution, and Role in Nature, Especially in Relation to Insect Behavior and Pollination


    Tan, Keng Hong; Nishida, Ritsuo


    This review discusses the occurrence and distribution (within a plant) of methyl eugenol in different plant species (> 450) from 80 families spanning many plant orders, as well as various roles this chemical plays in nature, especially in the interactions between tephritid fruit flies and plants.

  10. Synergistic effects in threshold models on networks (United States)

    Juul, Jonas S.; Porter, Mason A.


    Network structure can have a significant impact on the propagation of diseases, memes, and information on social networks. Different types of spreading processes (and other dynamical processes) are affected by network architecture in different ways, and it is important to develop tractable models of spreading processes on networks to explore such issues. In this paper, we incorporate the idea of synergy into a two-state ("active" or "passive") threshold model of social influence on networks. Our model's update rule is deterministic, and the influence of each meme-carrying (i.e., active) neighbor can—depending on a parameter—either be enhanced or inhibited by an amount that depends on the number of active neighbors of a node. Such a synergistic system models social behavior in which the willingness to adopt either accelerates or saturates in a way that depends on the number of neighbors who have adopted that behavior. We illustrate that our model's synergy parameter has a crucial effect on system dynamics, as it determines whether degree-k nodes are possible or impossible to activate. We simulate synergistic meme spreading on both random-graph models and networks constructed from empirical data. Using a heterogeneous mean-field approximation, which we derive under the assumption that a network is locally tree-like, we are able to determine which synergy-parameter values allow degree-k nodes to be activated for many networks and for a broad family of synergistic models.

  11. Threshold Concepts in Finance: Student Perspectives (United States)

    Hoadley, Susan; Kyng, Tim; Tickle, Leonie; Wood, Leigh N.


    Finance threshold concepts are the essential conceptual knowledge that underpin well-developed financial capabilities and are central to the mastery of finance. In this paper we investigate threshold concepts in finance from the point of view of students, by establishing the extent to which students are aware of threshold concepts identified by…

  12. Metal exposure and accumulation patterns in free-range cows (Bos taurus) in a contaminated natural area: Influence of spatial and social behavior

    International Nuclear Information System (INIS)

    Roggeman, Saskia; Brink, Nico van den; Van Praet, Nander; Blust, Ronny; Bervoets, Lieven


    Possible effects of spatial metal distribution, seasonal-, ecological- and ethological parameters, on the metal exposure of cows were investigated. Therefore the habitat use, vegetation selection and foraging behavior of two free ranging Galloway herds in a metal polluted nature reserve were observed. Metal concentrations in soil, vegetation, hair, blood and feces were measured. Although both herds lived in the same reserve, their metal exposure differed significantly. A high consumption of soft rush by herd 1 during winter for instance was responsible for a large increase in daily Cd intake. The results of this study suggest that the exposure and health risks of large grazers can probably not only be predicted by a general monitoring of soil and vegetation pollution. Also detailed information about the occurring vegetation types, spatial habitat use together with the social- and foraging behavior and diet selection of the species need to be studied. - Highlights: ► Vegetation selection, social behavior, and seasonal variation determine exposure. ► Soft rush consumption highly increased daily Cd intake during winter. ► Most Cd and Pb levels in vegetation exceeded the maximum tolerable feed levels. - This study reveals that spatial heterogeneity and foraging behavior play a more important role in the metal exposure pattern of large grazers than generally is presumed.

  13. Predicting Health Care Utilization After the First Behavioral Health Visit Using Natural Language Processing and Machine Learning


    Roysden, Nathaniel


    Mental health problems are an independent predictor of increased healthcare utilization. We created random forest classifiers for predicting two outcomes following a patient’s first behavioral health encounter: decreased utilization by any amount (AUROC 0.74) and ultra-high absolute utilization (AUROC 0.88). These models may be used for clinical decision support by referring providers, to automatically detect patients who may benefit from referral, for cost management, or for risk/protection ...

  14. Resetting of the Baroreflex Control of Sympathetic Vasomotor Activity during Natural Behaviors: Description and Conceptual Model of Central Mechanisms

    Directory of Open Access Journals (Sweden)

    Roger A. L. Dampney


    Full Text Available The baroreceptor reflex controls arterial pressure primarily via reflex changes in vascular resistance, rather than cardiac output. The vascular resistance in turn is dependent upon the activity of sympathetic vasomotor nerves innervating arterioles in different vascular beds. In this review, the major theme is that the baroreflex control of sympathetic vasomotor activity is not constant, but varies according to the behavioral state of the animal. In contrast to the view that was generally accepted up until the 1980s, I argue that the baroreflex control of sympathetic vasomotor activity is not inhibited or overridden during behaviors such as mental stress or exercise, but instead is reset under those conditions so that it continues to be highly effective in regulating sympathetic activity and arterial blood pressure at levels that are appropriate for the particular ongoing behavior. A major challenge is to identify the central mechanisms and neural pathways that subserve such resetting in different states. A model is proposed that is capable of simulating the different ways in which baroreflex resetting is occurred. Future studies are required to determine whether this proposed model is an accurate representation of the central mechanisms responsible for baroreflex resetting.

  15. Resetting of the Baroreflex Control of Sympathetic Vasomotor Activity during Natural Behaviors: Description and Conceptual Model of Central Mechanisms (United States)

    Dampney, Roger A. L.


    The baroreceptor reflex controls arterial pressure primarily via reflex changes in vascular resistance, rather than cardiac output. The vascular resistance in turn is dependent upon the activity of sympathetic vasomotor nerves innervating arterioles in different vascular beds. In this review, the major theme is that the baroreflex control of sympathetic vasomotor activity is not constant, but varies according to the behavioral state of the animal. In contrast to the view that was generally accepted up until the 1980s, I argue that the baroreflex control of sympathetic vasomotor activity is not inhibited or overridden during behaviors such as mental stress or exercise, but instead is reset under those conditions so that it continues to be highly effective in regulating sympathetic activity and arterial blood pressure at levels that are appropriate for the particular ongoing behavior. A major challenge is to identify the central mechanisms and neural pathways that subserve such resetting in different states. A model is proposed that is capable of simulating the different ways in which baroreflex resetting is occurred. Future studies are required to determine whether this proposed model is an accurate representation of the central mechanisms responsible for baroreflex resetting. PMID:28860965

  16. Threshold enhancement of diphoton resonances

    CERN Document Server

    Bharucha, Aoife; Goudelis, Andreas


    The data collected by the LHC collaborations at an energy of 13 TeV indicates the presence of an excess in the diphoton spectrum that would correspond to a resonance of a 750 GeV mass. The apparently large production cross section is nevertheless very difficult to explain in minimal models. We consider the possibility that the resonance is a pseudoscalar boson $A$ with a two--photon decay mediated by a charged and uncolored fermion having a mass at the $\\frac12 M_A$ threshold and a very small decay width, $\\ll 1$ MeV; one can then generate a large enhancement of the $A\\gamma\\gamma$ amplitude which explains the excess without invoking a large multiplicity of particles propagating in the loop, large electric charges and/or very strong Yukawa couplings. The implications of such a threshold enhancement are discussed in two explicit scenarios: i) the Minimal Supersymmetric Standard Model in which the $A$ state is produced via the top quark mediated gluon fusion process and decays into photons predominantly through...

  17. A note on the effect of the fiber curvature on the micromechanical behavior of natural fiber reinforced thermoplastic composites

    Directory of Open Access Journals (Sweden)

    M. A. Escalante-Solis


    Full Text Available To better understand the role of the fiber curvature on the tensile properties of short-natural-fiber reinforced composites, a photoelastic model and a finite element analysis were performed in a well characterized henequen fiber-high density polyethylene composite material. It was hypothesized that the angle of orientation of the inclusion and the principal material orientation with respect to the applied load was very important in the reinforcement mechanics. From the photoelastic and finite element analysis it was found that the stress distribution around the fiber inclusion was different on the concave side from that observed on the convex side and an efficient length of stress transfer was estimated to be approximately equal to one third the average fiber length. This approach was used to predict the short-natural-fiber reinforced composite mechanical properties using probabilistic functions modifications of the rule of mixtures models developed by Fukuda-Chow and the Fukuda-Kawata. Recognizing the inherent flexibility that curves the natural fibers during processing, the consideration of a length of one third of the average length l should improve the accuracy of the calculations of the mechanical properties using theoretical models.

  18. Speaking more broadly: an examination of the nature, antecedents, and consequences of an expanded set of employee voice behaviors. (United States)

    Maynes, Timothy D; Podsakoff, Philip M


    Scholarly interest in employee voice behavior has increased dramatically over the past 15 years. Although this research has produced valuable knowledge, it has focused almost exclusively on voice as a positively intended challenge to the status quo, even though some scholars have argued that it need not challenge the status quo or be well intentioned. Thus, in this paper, we create an expanded view of voice; one that extends beyond voice as a positively intended challenge to the status quo to include voice that supports how things are being done in organizations as well as voice that may not be well intentioned. We construct a framework based on this expanded view that identifies 4 different types of voice behavior (supportive, constructive, defensive, and destructive). We then develop and validate survey measures for each of these. Evidence from 5 studies across 4 samples provides strong support for our new measures in that (a) a 4-factor confirmatory factor analysis model fit the data significantly better than 1-, 2-, or 3-factor models; (b) the voice measures converged with and yet remained distinct from conceptually related comparison constructs; (c) personality predictors exhibited unique patterns of relationships with the different types of voice; (d) variations in actual voice behaviors had a direct causal impact on responses to the survey items; and (e) each type of voice significantly impacted important outcomes for voicing employees (e.g., likelihood of relying on a voicing employee's opinions and evaluations of a voicing employee's overall performance). Implications of our findings are discussed. PsycINFO Database Record (c) 2014 APA, all rights reserved

  19. Pestiferous nature, resting sites, aggregation, and host-seeking behavior of the eye fly Siphunculina funicola (Diptera: Chloropidae) in Thailand. (United States)

    Mulla, Mir S; Chansang, Uruyakorn


    Species of eye flies and eye gnats (Diptera: Chloropidae) are severe and persistent pests of man, domestic and wild animals, and potential vectors of pathogens. The species prevailing in the Oriental region belong to the genus Siphunculina, while those in the Neotropic and Nearctic regions belong to Liohippelates and Hippelates. These are small insects of 1-2 mm that feed on wounds, lacerations, scratches, and mucous membranes of man and higher animals. One species, Siphunculina funicola, commonly known as the Oriental eye fly, is considered the most anthropophilic in the genus, with potential involvement in the spread and mechanical transmission of infectious agents to humans and animals. Very little is known about the biology, prevalence, host-seeking, and aggregation behavior of this species in South and Southeast Asia. We initiated studies on biological aspects of this potential vector and human pest in central Thailand. The most significant findings of our study were the aggregation behaviors of S. funicola, that both sexes attack hosts, and that males outnumbered females attacking humans, dogs, and other domestic animals. They feed on wounds, scabs, lacerations, eyes, and mucous membranes. They hover around and feed on hosts during the daylight hours when host-seeking activities are more pronounced at temperatures above 25-27 degrees C under calm conditions. We noted that large masses of males and females aggregated on a variety of hanging objects such as strings, trailings, electrical lines, decorations, ropes, twines, abandoned cob webs, clothes hangers, and other hanging substrates in open shade of structures and dwellings. This behavior of eye flies brings them closer to human and animal hosts. In these aggregations, both males and females were present, with mating pairs frequently noted. In the aggregations, about 37% of the females had fully developed eggs in the rainy season, but only <1-3.6% were gravid in the hot and dry season. The average number of

  20. An integrative perspective of the anaerobic threshold. (United States)

    Sales, Marcelo Magalhães; Sousa, Caio Victor; da Silva Aguiar, Samuel; Knechtle, Beat; Nikolaidis, Pantelis Theodoros; Alves, Polissandro Mortoza; Simões, Herbert Gustavo


    The concept of anaerobic threshold (AT) was introduced during the nineteen sixties. Since then, several methods to identify the anaerobic threshold (AT) have been studied and suggested as novel 'thresholds' based upon the variable used for its detection (i.e. lactate threshold, ventilatory threshold, glucose threshold). These different techniques have brought some confusion about how we should name this parameter, for instance, anaerobic threshold or the physiological measure used (i.e. lactate, ventilation). On the other hand, the modernization of scientific methods and apparatus to detect AT, as well as the body of literature formed in the past decades, could provide a more cohesive understanding over the AT and the multiple physiological systems involved. Thus, the purpose of this review was to provide an integrative perspective of the methods to determine AT. Copyright © 2017 Elsevier Inc. All rights reserved.

  1. Short communication: Relationship between serum cortisol concentration and defensive behavioral responses of dairy cows exposed to natural infestation by stable fly, Stomoxys calcitrans. (United States)

    Vitela-Mendoza, I; Cruz-Vázquez, C; Solano-Vergara, J; Orihuela-Trujillo, A


    The aim of this study was conducted to evaluate the effect of natural infestation by Stomoxys calcitrans on the behavioral and adrenocortical responses of dairy cattle. Twenty Holstein cows randomly selected were individually sprayed with insecticide once every 7d, whereas no insecticide was applied to the other 20 animals. The average number of flies per cow was estimated daily, and the frequency of fly-avoidance behaviors was measured daily; plasma cortisol concentration was measured each morning. No flies were ever counted on the treated cows at any time during the experiment, whereas an average of 17.13±1.14 (±standard error) flies/d were recorded on untreated cows. Tail movement was the most frequent behavior displayed, with stamps or kicks showing the highest increment rate (41.2×) when fly population increased from zero to greater than 51 flies/cow. Cortisol concentration increased to a maximum of 56.81±39.53ng/mL with 26 to 30 flies/cow per day. Coefficients of determination between the number of flies, cortisol concentration, tail movements, and stamps or kicks were 0.73, 0.78, and 0.81, respectively. The multiple correlation coefficient was 0.90, with 81% of the variation in cortisol concentration explainable by variation in the number of flies per cow and the frequency of fly-avoidance behaviors. It was concluded that plasma cortisol concentration is linearly related to a combination of the number of flies and the frequency of fly-dislodging behaviors, producing a maximum response before reaching maximum fly loads. Copyright © 2016 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  2. Effects of copper and titanium on the corrosion behavior of newly fabricated nanocrystalline aluminum in natural seawater (United States)

    Sherif, El-Sayed M.; Ammar, Hany Rizk; Khalil, Khalil Abdelrazek


    Fabrication of a newly nanocrystalline Al and two of its alloys, namely Al-10%Cu; and Al-10%Cu-5%Ti has been carried out using mechanical alloying (MA) technique. The corrosion behavior of these materials in aerated stagnant Arabian Gulf seawater (AGSW) at room temperature has been reported. Cyclic potentiodynamic polarization (CPP), chronoamperometric current-time (CCT) and electrochemical impedance spectroscopy (EIS) measurements along with scanning electron microscopy (SEM) and X-ray energy dispersive (EDX) investigations were employed to report the corrosion behavior of the fabricated materials. All results indicated that Al suffers both uniform and localized corrosion in the AGSW test solution. The presence of 10%Cu decreases the corrosion current density, the anodic and cathodic currents and corrosion rate and increases the corrosion resistance of Al. The addition of 5%Ti to the Al-10%Cu alloy produced further decreases in the corrosion parameters. Measurements together confirmed that the corrosion of the fabricated materials in AGSW decreases in the order Al > Al-10%Cu > Al-10%Cu-5%Ti.

  3. Epidemic thresholds for bipartite networks (United States)

    Hernández, D. G.; Risau-Gusman, S.


    It is well known that sexually transmitted diseases (STD) spread across a network of human sexual contacts. This network is most often bipartite, as most STD are transmitted between men and women. Even though network models in epidemiology have quite a long history now, there are few general results about bipartite networks. One of them is the simple dependence, predicted using the mean field approximation, between the epidemic threshold and the average and variance of the degree distribution of the network. Here we show that going beyond this approximation can lead to qualitatively different results that are supported by numerical simulations. One of the new features, that can be relevant for applications, is the existence of a critical value for the infectivity of each population, below which no epidemics can arise, regardless of the value of the infectivity of the other population.

  4. Hydro-mechanical mechanism and thresholds of rainfall-induced unsaturated landslides (United States)

    Yang, Zongji; Lei, Xiaoqin; Huang, Dong; Qiao, Jianping


    The devastating Ms 8 Wenchuan earthquake in 2008 created the greatest number of co-seismic mountain hazards ever recorded in China. However, the dynamics of rainfall induced mass remobilization and transport deposits after giant earthquake are not fully understood. Moreover, rainfall intensity and duration (I-D) methods are the predominant early warning indicators of rainfall-induced landslides in post-earthquake region, which are a convenient and straight-forward way to predict the hazards. However, the rainfall-based criteria and thresholds are generally empirical and based on statistical analysis,consequently, they ignore the failure mechanisms of the landslides. This study examines the mechanism and hydro-mechanical behavior and thresholds of these unsaturated deposits under the influence of rainfall. To accomplish this, in situ experiments were performed in an instrumented landslide deposit, The field experimental tests were conducted on a natural co-seismic fractured slope to 1) simulate rainfall-induced shallow failures in the depression channels of a debris flow catchment in an earthquake-affected region, 2)explore the mechanisms and transient processes associated with hydro-mechanical parameter variations in response to the infiltration of rainfall, and 3) identify the hydrologic parameter thresholds and critical criteria of gravitational erosion in areas prone to mass remobilization as a source of debris flows. These experiments provided instrumental evidence and directly proved that post-earthquake rainfall-induced mass remobilization occurred under unsaturated conditions in response to transient rainfall infiltration, and revealed the presence of transient processes and the dominance of preferential flow paths during rainfall infiltration. A hydro-mechanical method was adopted for the transient hydrologic process modelling and unsaturated slope stability analysis. and the slope failures during the experimental test were reproduced by the model

  5. Electrochemical behavior and corrosion resistance of Ti-15Mo alloy in naturally-aerated solutions, containing chloride and fluoride ions. (United States)

    Rodrigues, A V; Oliveira, N T C; dos Santos, M L; Guastaldi, A C


    The electrochemical behavior and corrosion resistance of Ti-15Mo alloy to applications as biomaterials in solutions 0.15 mol L(-1) Ringer, 0.15 mol L(-1) Ringer plus 0.036 mol L(-1) NaF and 0.036 mol L(-1) NaF (containing 1,500 ppm of fluoride ions, F(-)) were investigated using open-circuit potential, cyclic voltammetry, and electrochemical impedance spectroscopy techniques, X-ray photoelectron spectroscopy and scanning electron microscope. Corrosion resistance and electrochemical stability of the Ti-15Mo alloy decreased in solutions containing F(-) ions. In all cases, there were formation and growth of TiO2 and MoO3 (a protector film), not being observed pitting corrosion, which might enable Ti-15Mo alloys to be used as biomedical implant, at least in the studied conditions, since the electrochemical stability and corrosion resistance of the passive films formed are necessary conditions for osseointegration.

  6. Fire, fuel composition and resilience threshold in subalpine ecosystem.

    Directory of Open Access Journals (Sweden)

    Olivier Blarquez

    Full Text Available BACKGROUND: Forecasting the effects of global changes on high altitude ecosystems requires an understanding of the long-term relationships between biota and forcing factors to identify resilience thresholds. Fire is a crucial forcing factor: both fuel build-up from land-abandonment in European mountains, and more droughts linked to global warming are likely to increase fire risks. METHODS: To assess the vegetation response to fire on a millennium time-scale, we analyzed evidence of stand-to-local vegetation dynamics derived from sedimentary plant macroremains from two subalpine lakes. Paleobotanical reconstructions at high temporal resolution, together with a fire frequency reconstruction inferred from sedimentary charcoal, were analyzed by Superposed Epoch Analysis to model plant behavior before, during and after fire events. PRINCIPAL FINDINGS: We show that fuel build-up from arolla pine (Pinus cembra always precedes fires, which is immediately followed by a rapid increase of birch (Betula sp., then by ericaceous species after 25-75 years, and by herbs after 50-100 years. European larch (Larix decidua, which is the natural co-dominant species of subalpine forests with Pinus cembra, is not sensitive to fire, while the abundance of Pinus cembra is altered within a 150-year period after fires. A long-term trend in vegetation dynamics is apparent, wherein species that abound later in succession are the functional drivers, loading the environment with fuel for fires. This system can only be functional if fires are mainly driven by external factors (e.g. climate, with the mean interval between fires being longer than the minimum time required to reach the late successional stage, here 150 years. CONCLUSION: Current global warming conditions which increase drought occurrences, combined with the abandonment of land in European mountain areas, creates ideal ecological conditions for the ignition and the spread of fire. A fire return interval of less

  7. Fire, fuel composition and resilience threshold in subalpine ecosystem. (United States)

    Blarquez, Olivier; Carcaillet, Christopher


    Forecasting the effects of global changes on high altitude ecosystems requires an understanding of the long-term relationships between biota and forcing factors to identify resilience thresholds. Fire is a crucial forcing factor: both fuel build-up from land-abandonment in European mountains, and more droughts linked to global warming are likely to increase fire risks. To assess the vegetation response to fire on a millennium time-scale, we analyzed evidence of stand-to-local vegetation dynamics derived from sedimentary plant macroremains from two subalpine lakes. Paleobotanical reconstructions at high temporal resolution, together with a fire frequency reconstruction inferred from sedimentary charcoal, were analyzed by Superposed Epoch Analysis to model plant behavior before, during and after fire events. We show that fuel build-up from arolla pine (Pinus cembra) always precedes fires, which is immediately followed by a rapid increase of birch (Betula sp.), then by ericaceous species after 25-75 years, and by herbs after 50-100 years. European larch (Larix decidua), which is the natural co-dominant species of subalpine forests with Pinus cembra, is not sensitive to fire, while the abundance of Pinus cembra is altered within a 150-year period after fires. A long-term trend in vegetation dynamics is apparent, wherein species that abound later in succession are the functional drivers, loading the environment with fuel for fires. This system can only be functional if fires are mainly driven by external factors (e.g. climate), with the mean interval between fires being longer than the minimum time required to reach the late successional stage, here 150 years. Current global warming conditions which increase drought occurrences, combined with the abandonment of land in European mountain areas, creates ideal ecological conditions for the ignition and the spread of fire. A fire return interval of less than 150 years would threaten the dominant species and might override

  8. Comparing the locking threshold for rings and chains of oscillators (United States)

    Ottino-Löffler, Bertrand; Strogatz, Steven H.


    We present a case study of how topology can affect synchronization. Specifically, we consider arrays of phase oscillators coupled in a ring or a chain topology. Each ring is perfectly matched to a chain with the same initial conditions and the same random natural frequencies. The only difference is their boundary conditions: periodic for a ring and open for a chain. For both topologies, stable phase-locked states exist if and only if the spread or "width" of the natural frequencies is smaller than a critical value called the locking threshold (which depends on the boundary conditions and the particular realization of the frequencies). The central question is whether a ring synchronizes more readily than a chain. We show that it usually does, but not always. Rigorous bounds are derived for the ratio between the locking thresholds of a ring and its matched chain, for a variant of the Kuramoto model that also includes a wider family of models.

  9. Natural rubber/graphene oxide composites: Effect of sheet size on mechanical properties and strain-induced crystallization behavior

    Directory of Open Access Journals (Sweden)

    X. Wu


    Full Text Available In order to analyze the influence of the lateral size of graphene oxide (GO on the properties of natural rubber/graphene oxide (NR/GO nanocomposites, three different sized graphene oxide sheets, namely G1, G2 and G3 were used to fabricate a series of NR/GO nanocomposites by latex mixing. The results indicate that adding GO can remarkably increase the modulus of NR. The enhancement of modulus is strongly dependent on the size of GO sheets incorporated. G1 with smallest sheet size gives the maximum reinforcement effect compared with G2 and G3. Dynamic mechanical measurement and swelling ratios (Qf/Qg indicate that G1 has stronger interfacial interaction with NR. XRD shows G1 is more effective in accelerating the strain-induced crystallization (SIC of NR. The strong interfacial interaction facilitates the stress transfer and strain-induced crystallization, both of which lead to the improved modulus.

  10. Understanding the nature of information seeking behavior in critical care: implications for the design of health information technology. (United States)

    Kannampallil, Thomas G; Franklin, Amy; Mishra, Rashmi; Almoosa, Khalid F; Cohen, Trevor; Patel, Vimla L


    Information in critical care environments is distributed across multiple sources, such as paper charts, electronic records, and support personnel. For decision-making tasks, physicians have to seek, gather, filter and organize information from various sources in a timely manner. The objective of this research is to characterize the nature of physicians' information seeking process, and the content and structure of clinical information retrieved during this process. Eight medical intensive care unit physicians provided a verbal think-aloud as they performed a clinical diagnosis task. Verbal descriptions of physicians' activities, sources of information they used, time spent on each information source, and interactions with other clinicians were captured for analysis. The data were analyzed using qualitative and quantitative approaches. We found that the information seeking process was exploratory and iterative and driven by the contextual organization of information. While there was no significant differences between the overall time spent paper or electronic records, there was marginally greater relative information gain (i.e., more unique information retrieved per unit time) from electronic records (t(6)=1.89, p=0.1). Additionally, information retrieved from electronic records was at a higher level (i.e., observations and findings) in the knowledge structure than paper records, reflecting differences in the nature of knowledge utilization across resources. A process of local optimization drove the information seeking process: physicians utilized information that maximized their information gain even though it required significantly more cognitive effort. Implications for the design of health information technology solutions that seamlessly integrate information seeking activities within the workflow, such as enriching the clinical information space and supporting efficient clinical reasoning and decision-making, are discussed. Copyright © 2012 Elsevier B.V. All

  11. Incentivizing energy-efficient behavior at work: An empirical investigation using a natural field experiment on eco-driving

    International Nuclear Information System (INIS)

    Schall, Dominik L.; Mohnen, Alwine


    Highlights: • We conduct a natural field experiment on incentives for fuel-efficient driving. • A monetary and a tangible non-monetary reward for eco-driving are compared. • The non-monetary reward results in an average reduction of fuel consumption of 5%. • There is only a small reduction effect in the equivalent monetary reward treatment. • Emphasis of fun, emotional responses and frequency of recalling might play a role. - Abstract: Reducing greenhouse gas emissions is a highly prevalent goal of public policy in many countries around the world. Convincing people to drive more fuel-efficiently (“eco-driving”) can contribute substantially to this goal and is often an integral part of policy initiatives. However, there is a lack of scientific studies on the effects of individual monetary and non-monetary incentives for eco-driving, especially in organizational settings and with regards to demonstrating causality, e.g., by using controlled experiments. We address this gap with a six months long controlled natural field experiment and introduce a monetary and a non-monetary reward for eco-driving to drivers of light commercial vehicles in different branches of a logistics company. Our results show an average reduction of fuel consumption of 5% due to a tangible non-monetary reward and suggest only a small reduction of the average fuel consumption in the equivalent monetary reward treatment. We find indications that more emphasis on the fun of achieving a higher fuel efficiency, a more emotional response to non-monetary incentives, and a higher frequency of thinking and talking about non-monetary incentives might play a role in the stronger effect of the tangible non-monetary reward. Policy implications for private and public actors are discussed.

  12. An immuno-epidemiological model with threshold delay: a study of the effects of multiple exposures to a pathogen. (United States)

    Qesmi, Redouane; Heffernan, Jane M; Wu, Jianhong


    An immuno-epidemiological model of pathogen transmission is developed. This model incorporates two main features: (i) the epidemiological model includes within-host pathogen dynamics for an infectious disease, (ii) the susceptible individuals to the infection experience a series of exposures via the pathogen before becoming infectious. It is shown that this model leads naturally to a system of differential delay equations of the threshold type and that these equations can be transformed, in a biologically natural way, to differential equations with state-dependent delay. An interesting dynamical behavior of the model is the bistability phenomena, when the basic reproductive ratio R0 is less than unity, which raises many new challenges to effective infection control.

  13. Influence of the anion nature and alkyl substituents in the behavior of ionic liquids derived from phenylpyridines (United States)

    Dreyse, Paulina; Alarcón, Antonia; Galdámez, Antonio; González, Iván; Cortés-Arriagada, Diego; Castillo, Francisco; Mella, Andy


    Quaternary alkyl 2-phenylpyridinium and 2-(2,4-difluorophenyl)pyridinium amines with iodide, hexafluorophosphate and bis(trifluoromethylsulfonyl)imide anions have been fully characterized by 1H NMR, FT-IR and MALDI mass spectroscopic methods and studied by quantum chemistry calculations. The compounds with bis(trifluoromethylsulfonyl)imide anion can be classified as ionic liquids, because they melt at room temperature. The quaternary amines with iodide and hexafluorophosphate anions are solid at 25 °C. The X-ray diffraction characterization of the 2-(2,4-difluorophenyl)-1-methylphenylpyridinium hexafluorophosphate and 1-ethyl-2-(2,4-difluorophenyl)phenylpyridinium hexafluorophosphate show an extensive series of Csbnd H⋯F, Csbnd F⋯π and Psbnd F⋯π intermolecular interactions, which give rise to a supramolecular network. The relationship between the solid-state structures and the melting points is discussed by the evaluation of the thermal behavior based on experimental data from Differential Scanning Calorimetry (DSC) studies, and also using the analysis of the ion pairs binding energies. These new compounds based on phenylpyridine allow us to grow the diversity of ionic liquids and their crystalline salts, increasing the knowledge about the chemical and physical properties of these ionic species.

  14. The influence of the nature and textural properties of different supports on the thermal behavior of Keggin type heteropolyacids

    Directory of Open Access Journals (Sweden)



    Full Text Available In order to obtain highly dispersed heteropolyacids (HPAs species, H3PMo12VO40 and H3PVMo11O40 were supported on various supports: silica (Aerosil - Degussa and Romsil types and TiO2. The structure and thermal decomposition of supported and unsupported HPAs were followed by different techniques (TGA-DTA, FTIR, XRD, low temperature nitrogen adsorption, scanning electron microscopy. All the supported HPAs were prepared by impregnation using the incipient wetness technique with a 1:1 mixture of water–ethanol. Samples were prepared with different concentrations to examine the effect of loading on the thermal behavior of the supported acid catalysts. The thermal stability was evaluated with reference to the bulk solid acids and mechanical mixtures. After deposition on silica types supports, an important decrease in thermal stability was observed on the Romsil types and a small decrease on the Aerosil type. The stability of the heteropolyacids supported on titania increased due to an anion-support interaction, as the thermal decomposition proceeded in two steps. The structure of the HPAs was not totally destroyed at 450 ºC as some IR bands were still preserved. A relatively uniform distribution of HPAs on the support surface was observed for all compositions of the active phase. No separate crystallites of solid phase HPAs were found in the SEM images.

  15. Iran: the next nuclear threshold state?


    Maurer, Christopher L.


    Approved for public release; distribution is unlimited A nuclear threshold state is one that could quickly operationalize its peaceful nuclear program into one capable of producing a nuclear weapon. This thesis compares two known threshold states, Japan and Brazil, with Iran to determine if the Islamic Republic could also be labeled a threshold state. Furthermore, it highlights the implications such a status could have on U.S. nonproliferation policy. Although Iran's nuclear program is mir...

  16. Roots at the percolation threshold. (United States)

    Kroener, Eva; Ahmed, Mutez Ali; Carminati, Andrea


    The rhizosphere is the layer of soil around the roots where complex and dynamic interactions between plants and soil affect the capacity of plants to take up water. The physical properties of the rhizosphere are affected by mucilage, a gel exuded by roots. Mucilage can absorb large volumes of water, but it becomes hydrophobic after drying. We use a percolation model to describe the rewetting of dry rhizosphere. We find that at a critical mucilage concentration the rhizosphere becomes impermeable. The critical mucilage concentration depends on the radius of the soil particle size. Capillary rise experiments with neutron radiography prove that for concentrations below the critical mucilage concentration water could easily cross the rhizosphere, while above the critical concentration water could no longer percolate through it. Our studies, together with former observations of water dynamics in the rhizosphere, suggest that the rhizosphere is near the percolation threshold, where small variations in mucilage concentration sensitively alter the soil hydraulic conductivity. Is mucilage exudation a plant mechanism to efficiently control the rhizosphere conductivity and the access to water?

  17. Percolation Threshold in Polycarbonate Nanocomposites (United States)

    Ahuja, Suresh


    Nanocomposites have unique mechanical, electrical, magnetic, optical and thermal properties. Many methods could be applied to prepare polymer-inorganic nanocomposites, such as sol-gel processing, in-situ polymerization, particle in-situ formation, blending, and radiation synthesis. The analytical composite models that have been put forth include Voigt and Reuss bounds, Polymer nanocomposites offer the possibility of substantial improvements in material properties such as shear and bulk modulus, yield strength, toughness, film scratch resistance, optical properties, electrical conductivity, gas and solvent transport, with only very small amounts of nanoparticles Experimental results are compared against composite models of Hashin and Shtrikman bounds, Halpin-Tsai model, Cox model, and various Mori and Tanaka models. Examples of numerical modeling are molecular dynamics modeling and finite element modeling of reduced modulus and hardness that takes into account the modulus of the components and the effect of the interface between the hard filler and relatively soft polymer, polycarbonate. Higher nanoparticle concentration results in poor dispersion and adhesion to polymer matrix which results in lower modulus and hardness and departure from the existing composite models. As the level of silica increases beyond a threshold level, aggregates form which results in weakening of the structure. Polymer silica interface is found to be weak as silica is non-interacting promoting interfacial slip at silica-matrix junctions. Our experimental results compare favorably with those of nanocomposites of polyesters where the effect of nanoclay on composite hardness and modulus depended on dispersion of nanoclay in polyester.

  18. Dynamical thresholds for complete fusion

    International Nuclear Information System (INIS)

    Davies, K.T.R.; Sierk, A.J.; Nix, J.R.


    It is our purpose here to study the effect of nuclear dissipation and shape parametrization on dynamical thresholds for compound-nucleus formation in symmetric heavy-ion reactions. This is done by solving numerically classical equations of motion for head-on collisions to determine whether the dynamical trajectory in a multidimensional deformation space passes inside the fission saddle point and forms a compound nucleus, or whether it passes outside the fission saddle point and reseparates in a fast-fission or deep-inelastic reaction. Specifying the nuclear shape in terms of smoothly joined portions of three quadratic surfaces of revolution, we take into account three symmetric deformation coordinates. However, in some cases we reduce the number of coordinates to two by requiring the ends of the fusing system to be spherical in shape. The nuclear potential energy of deformation is determined in terms of a Coulomb energy and a double volume energy of a Yukawa-plus-exponential folding function. The collective kinetic energy is calculated for incompressible, nearly irrotational flow by means of the Werner-Wheeler approximation. Four possibilities are studied for the transfer of collective kinetic energy into internal single-particle excitation energy: zero dissipation, ordinary two body viscosity, one-body wall-formula dissipation, and one-body wall-and-window dissipation

  19. Efficient threshold for volumetric segmentation (United States)

    Burdescu, Dumitru D.; Brezovan, Marius; Stanescu, Liana; Stoica Spahiu, Cosmin; Ebanca, Daniel


    Image segmentation plays a crucial role in effective understanding of digital images. However, the research on the existence of general purpose segmentation algorithm that suits for variety of applications is still very much active. Among the many approaches in performing image segmentation, graph based approach is gaining popularity primarily due to its ability in reflecting global image properties. Volumetric image segmentation can simply result an image partition composed by relevant regions, but the most fundamental challenge in segmentation algorithm is to precisely define the volumetric extent of some object, which may be represented by the union of multiple regions. The aim in this paper is to present a new method to detect visual objects from color volumetric images and efficient threshold. We present a unified framework for volumetric image segmentation and contour extraction that uses a virtual tree-hexagonal structure defined on the set of the image voxels. The advantage of using a virtual tree-hexagonal network superposed over the initial image voxels is that it reduces the execution time and the memory space used, without losing the initial resolution of the image.

  20. Consolidation by Prefabricated Vertical Drains with a Threshold Gradient

    Directory of Open Access Journals (Sweden)

    Xiao Guo


    Full Text Available This paper shows the development of an approximate analytical solution of radial consolidation by prefabricated vertical drains with a threshold gradient. To understand the effect of the threshold gradient on consolidation, a parametric analysis was performed using the present solution. The applicability of the present solution was demonstrated in two cases, wherein the comparisons with Hansbo’s results and observed data were conducted. It was found that (1 the flow with the threshold gradient would not occur instantaneously throughout the whole unit cell. Rather, it gradually occurs from the vertical drain to the outside; (2 the moving boundary would never reach the outer radius of influence if R+1threshold gradient is, the greater the long-term excess pore pressure will be; and (5 the present solution could predict the consolidation behavior in soft clay better than previous methods.

  1. Error Thresholds on Dynamic Fittness-Landscapes


    Nilsson, Martin; Snoad, Nigel


    In this paper we investigate error-thresholds on dynamics fitness-landscapes. We show that there exists both lower and an upper threshold, representing limits to the copying fidelity of simple replicators. The lower bound can be expressed as a correction term to the error-threshold present on a static landscape. The upper error-threshold is a new limit that only exists on dynamic fitness-landscapes. We also show that for long genomes on highly dynamic fitness-landscapes there exists a lower b...

  2. MOS Current Mode Logic Near Threshold Circuits

    Directory of Open Access Journals (Sweden)

    Alexander Shapiro


    Full Text Available Near threshold circuits (NTC are an attractive and promising technology that provides significant power savings with some delay penalty. The combination of NTC technology with MOS current mode logic (MCML is examined in this work. By combining MCML with NTC, the constant power consumption of MCML is reduced to leakage power levels that can be tolerated in certain modern applications. Additionally, the speed of NTC is improved due to the high speed nature of MCML technology. A 14 nm Fin field effect transistor (FinFET technology is used to evaluate these combined circuit techniques. A 32-bit Kogge Stone adder is chosen as a demonstration vehicle for feasibility analysis. MCML with NTC is shown to yield enhanced power efficiency when operated above 1 GHz with a 100% activity factor as compared to standard CMOS. MCML with NTC is more power efficient than standard CMOS beyond 9 GHz over a wide range of activity factors. MCML with NTC also exhibits significantly lower noise levels as compared to standard CMOS. The results of the analysis demonstrate that pairing NTC and MCML is efficient when operating at high frequencies and activity factors.

  3. Dimensional threshold for fracture linkage and hooking (United States)

    Lamarche, Juliette; Chabani, Arezki; Gauthier, Bertrand D. M.


    Fracture connectivity in rocks depends on spatial properties of the pattern including length, abundance and orientation. When fractures form a single-strike set, they hardly cross-cut each other and the connectivity is limited. Linkage probability increases with increasing fracture abundance and length as small fractures connect to each other to form longer ones. A process for parallel fracture linkage is the "hooking", where two converging fracture tips mutually deviate and then converge to connect due to the interaction of their crack-tip stresses. Quantifying the processes and conditions for fracture linkage in single-strike fracture sets is crucial to better predicting fluid flow in Naturally Fractured Reservoirs. For 1734 fractures in Permian shales of the Lodève Basin, SE France, we measured geometrical parameters in 2D, characterizing three stages of the hooking process: underlapping, overlapping and linkage. We deciphered the threshold values, shape ratios and limiting conditions to switch from one stage to another one. The hook set up depends on the spacing (S) and fracture length (Lh) with the relation S ≈ 0.15 Lh. Once the hooking is initiated, with the fracture deviation length (L) L ≈ 0.4 Lh, the fractures reaches the linkage stage only when the spacing is reduced to S ≈ 0.02 Lh and the convergence (C) is < 0.1 L. These conditions apply to multi-scale fractures with a shape ratio L/S = 10 and for fracture curvature of 10°-20°.

  4. Threshold nonlinear absorption in Zeeman transitions

    International Nuclear Information System (INIS)

    Narayanan, Andal; Hazra, Abheera; Sandhya, S N


    We experimentally study the absorption spectroscopy from a collection of gaseous 87 Rb atoms at room temperature irradiated with three fields. Two of these fields are in a pump-probe saturation absorption configuration. The third field co-propagates with the pump field. The three fields address Zeeman degenerate transitions between hyperfine levels 5S 1/2 , F = 1 and 5P 3/2 , F = 0, F = 1 around the D2 line. We find a sub-natural absorption resonance in the counter-propagating probe field for equal detunings of all three fields. This absorption arises in conjunction with the appearance of increased transmission due to electro-magnetically induced transparency in the co-propagating fields. The novel feature of this absorption is its onset only for the blue of 5P 3/2 , F = 0, as the laser frequency is scanned through the excited states 5P 3/2 , F = 0, F = 1 and F = 2. The absorption rapidly rises to near maximum values within a narrow band of frequency near 5P 3/2 , F = 0. Our experimental results are compared with a dressed atom model. We find the threshold absorption to be a result of coherent interaction between the dressed states of our system.

  5. On the Instability Threshold of Journal Bearing Supported Rotors

    Directory of Open Access Journals (Sweden)

    Ricardo Ugliara Mendes


    Full Text Available Journal bearing supported rotors present two kinds of self-excited vibrations: oil-whirl and oil-whip. The first one is commonly masked by the rotor unbalance, hence being rarely associated with instability problems. Oil-whip is a severe vibration which occurs when the oil-whirl frequency coincides with the first flexural natural frequency of the shaft. In many cases, oil-whip is the only fluid-induced instability considered during the design stage; however, experimental evidences have shown that the instability threshold may occur much sooner, demanding a better comprehension of the instability mechanism. In this context, numerical simulations were made in order to improve the identification of the instability threshold for two test rig configurations: one on which the instability occurs on the oil-whip frequency, and another which became unstable before this threshold. Therefore, the main contribution of this paper is to present an investigation of two different thresholds of fluid-induced instabilities and their detectability on design stage simulations based on rotordynamic analysis using linear speed dependent coefficients for the bearings.

  6. Integration of ecological-biological thresholds in conservation decision making. (United States)

    Mavrommati, Georgia; Bithas, Kostas; Borsuk, Mark E; Howarth, Richard B


    In the Anthropocene, coupled human and natural systems dominate and only a few natural systems remain relatively unaffected by human influence. On the one hand, conservation criteria based on areas of minimal human impact are not relevant to much of the biosphere. On the other hand, conservation criteria based on economic factors are problematic with respect to their ability to arrive at operational indicators of well-being that can be applied in practice over multiple generations. Coupled human and natural systems are subject to economic development which, under current management structures, tends to affect natural systems and cross planetary boundaries. Hence, designing and applying conservation criteria applicable in real-world systems where human and natural systems need to interact and sustainably coexist is essential. By recognizing the criticality of satisfying basic needs as well as the great uncertainty over the needs and preferences of future generations, we sought to incorporate conservation criteria based on minimal human impact into economic evaluation. These criteria require the conservation of environmental conditions such that the opportunity for intergenerational welfare optimization is maintained. Toward this end, we propose the integration of ecological-biological thresholds into decision making and use as an example the planetary-boundaries approach. Both conservation scientists and economists must be involved in defining operational ecological-biological thresholds that can be incorporated into economic thinking and reflect the objectives of conservation, sustainability, and intergenerational welfare optimization. © 2016 Society for Conservation Biology.

  7. Rainfall thresholds as a landslide indicator for engineered slopes on the Irish Rail network (United States)

    Martinović, Karlo; Gavin, Kenneth; Reale, Cormac; Mangan, Cathal


    Rainfall thresholds express the minimum levels of rainfall that need to be reached or exceeded in order for landslides to occur in a particular area. They are a common tool in expressing the temporal portion of landslide hazard analysis. Numerous rainfall thresholds have been developed for different areas worldwide, however none of these are focused on landslides occurring on the engineered slopes on transport infrastructure networks. This paper uses empirical method to develop the rainfall thresholds for landslides on the Irish Rail network earthworks. For comparison, rainfall thresholds are also developed for natural terrain in Ireland. The results show that particular thresholds involving relatively low rainfall intensities are applicable for Ireland, owing to the specific climate. Furthermore, the comparison shows that rainfall thresholds for engineered slopes are lower than those for landslides occurring on the natural terrain. This has severe implications as it indicates that there is a significant risk involved when using generic weather alerts (developed largely for natural terrain) for infrastructure management, and showcases the need for developing railway and road specific rainfall thresholds for landslides.

  8. The Higgs portal above threshold

    Energy Technology Data Exchange (ETDEWEB)

    Craig, Nathaniel [Department of Physics, University of California,Santa Barbara, CA 93106 (United States); Lou, Hou Keong [Department of Physics, Princeton University,Princeton, NJ 08540 (United States); McCullough, Matthew [Theory Division, CERN,1211 Geneva 23 (Switzerland); Thalapillil, Arun [Department of Physics and Astronomy, Rutgers University,Piscataway, NJ 08854 (United States)


    The discovery of the Higgs boson opens the door to new physics interacting via the Higgs Portal, including motivated scenarios relating to baryogenesis, dark matter, and electroweak naturalness. We systematically explore the collider signatures of singlet scalars produced via the Higgs Portal at the 14 TeV LHC and a prospective 100 TeV hadron collider. We focus on the challenging regime where the scalars are too heavy to be produced in the decays of an on-shell Higgs boson, and instead are produced primarily via an off-shell Higgs. Assuming these scalars escape the detector, promising channels include missing energy in association with vector boson fusion, monojets, and top pairs. We forecast the sensitivity of searches in these channels at √s=14 & 100 TeV and compare collider reach to the motivated parameter space of singlet-assisted electroweak baryogenesis, Higgs Portal dark matter, and neutral naturalness.

  9. Preparation and stress-strain behavior of in-situ epoxidized natural rubber/SiO2 hybrid through a sol-gel method

    Directory of Open Access Journals (Sweden)

    S. M. Li


    Full Text Available In this paper, epoxidized natural rubber was reinforced by silica generated in-situ though the sol-gel method using tetraethoxysilane(TEOS as precursor. The results showed that the ring opening reaction of epoxy group appeared in the in-situ reaction progress, where the hydrogen bond between Si–OH and C–OH was mainly formed to enhance the stress-strain behavior of ESH simultaneously. During the hot pressing progress, the compound was crosslinked via the chemical reaction of Si–OH and C–OH. The chemical bond between Si–OH and C–OH reinforced rubber-filler interaction, resulting further improved the stress-strain behavior. Besides, comparing with precipitated SiO2 filled ENR, the dispersion of SiO2 in ENR matrix was distinctly more uniform though the sol-gel method, along with the enhancement of mechanical properties. Herein, our findings open up a new way to prepare an environmentally friendly rubber composite with excellent dispersion and strong rubber-filler interaction without curing agent effectively.

  10. Eye-Tracking Technology and the Dynamics of Natural Gaze Behavior in Sports: A Systematic Review of 40 Years of Research. (United States)

    Kredel, Ralf; Vater, Christian; Klostermann, André; Hossner, Ernst-Joachim


    Reviewing 60 studies on natural gaze behavior in sports, it becomes clear that, over the last 40 years, the use of eye-tracking devices has considerably increased. Specifically, this review reveals the large variance of methods applied, analyses performed, and measures derived within the field. The results of sub-sample analyses suggest that sports-related eye-tracking research strives, on the one hand, for ecologically valid test settings (i.e., viewing conditions and response modes), while on the other, for experimental control along with high measurement accuracy (i.e., controlled test conditions with high-frequency eye-trackers linked to algorithmic analyses). To meet both demands, some promising compromises of methodological solutions have been proposed-in particular, the integration of robust mobile eye-trackers in motion-capture systems. However, as the fundamental trade-off between laboratory and field research cannot be solved by technological means, researchers need to carefully weigh the arguments for one or the other approach by accounting for the respective consequences. Nevertheless, for future research on dynamic gaze behavior in sports, further development of the current mobile eye-tracking methodology seems highly advisable to allow for the acquisition and algorithmic analyses of larger amounts of gaze-data and further, to increase the explanatory power of the derived results.

  11. Use of personal EEG monitors in a behavioral neuroscience course to investigate natural setting sleep patterns and the factors affecting them in college students. (United States)

    Marshall, Jillian C; Malerba, Julie R; Schroeder, Joseph A


    Sleep is often a topic of avid interest to college students, yet it is one that does not yield itself well to hands-on, interactive learning modules. Supplementing classroom learning with interactive "real world" laboratory activities provides students with a deeper understanding of behavior and its neural control. The project described here was designed to supplement the teaching of EEGs, sleep and circadian rhythms and involved students in the empirical process from hypothesizing about the factors that affect sleep, to personal data collection, data analysis and writing in the style of a peer-reviewed manuscript. Students enrolled in Behavioral Neuroscience at Connecticut College were provided with a home-based personal EEG monitor used to collect sleep data in their natural sleep setting. Participants recorded sleep data with the use of the ZEO® Personal Sleep Coach system and completed a nightly sleep journal questionnaire for seven nights. The ZEO® system uses EEG patterns to define sleep stages including wakefulness, light, deep and REM sleep. The journal included questions about factors known to affect sleep such as stress, caffeine, academic activity, exercise and alcohol. A class data set was compiled and used by students to perform univariate correlations examining the relationships between ZEO® variables and sleep journal variables. The data set allowed students to choose specific variables to investigate, analyze and write a peer-reviewed style manuscript. Significant class-wide correlations were found between specific sleep stages and behavioral variables suggesting that the ZEO® system is sophisticated yet inexpensive enough to be used as an effective tool in the classroom setting. Overall student feedback on the exercise was positive with many students indicating that it significantly enhanced their understanding of sleep architecture and made them keenly aware of the factors that affect quality of sleep.

  12. Threshold behavior for longitudinal stability of induction linac bunches

    International Nuclear Information System (INIS)

    Bisognano, J.; Haber, I.; Smith, L.


    The induction linac bunches of heavy ion fusion scenarios are strongly influenced by the longitudinal space charge impedance. This is in distinct contrast to relativistic bunches in storage rings where most of the data on stability have been obtained. Simulation results reveal that when space charge effects are large, the stability requirement of small growth rate relative to the synchrotron frequency for relativistic bunches is replaced by the relaxed condition of small growth rate relative to the frequency spacing of the space charge wave modes on the bunch. Dispersive effects from finite pipe size tend to make the lower frequencies less susceptible to instability than higher frequencies. Since induction modules have a high resistive component only for the lowest bunch modes, stability is better than would occur for a broadband impedance of comparable magnitude. These results indicate that long term longitudinal bunch stability is realizable for induction linac drivers for heavy ion fusion

  13. Role of propagation thresholds in sentiment-based model of opinion evolution with information diffusion (United States)

    Si, Xia-Meng; Wang, Wen-Dong; Ma, Yan


    The degree of sentiment is the key factor for internet users in determining their propagating behaviors, i.e. whether participating in a discussion and whether withdrawing from a discussion. For this end, we introduce two sentiment-based propagation thresholds (i.e. infected threshold and refractory threshold) and propose an interacting model based on the Bayesian updating rules. Our model describe the phenomena that few internet users change their decisions and that someone has drop out of discussion about the topic when some others are just aware of it. Numerical simulations show that, large infected threshold restrains information diffusion but favors the lessening of extremism, while large refractory threshold facilitates decision interaction but promotes the extremism. Making netizens calm down and propagate information sanely can restrain the prevailing of extremism about rumors.

  14. Time-efficient multidimensional threshold tracking method

    DEFF Research Database (Denmark)

    Fereczkowski, Michal; Kowalewski, Borys; Dau, Torsten


    Traditionally, adaptive methods have been used to reduce the time it takes to estimate psychoacoustic thresholds. However, even with adaptive methods, there are many cases where the testing time is too long to be clinically feasible, particularly when estimating thresholds as a function of anothe...

  15. Applying Threshold Concepts to Finance Education (United States)

    Hoadley, Susan; Wood, Leigh N.; Tickle, Leonie; Kyng, Tim


    Purpose: The purpose of this paper is to investigate and identify threshold concepts that are the essential conceptual content of finance programmes. Design/Methodology/Approach: Conducted in three stages with finance academics and students, the study uses threshold concepts as both a theoretical framework and a research methodology. Findings: The…

  16. Voting on Thresholds for Public Goods

    DEFF Research Database (Denmark)

    Rauchdobler, Julian; Sausgruber, Rupert; Tyran, Jean-Robert


    Introducing a threshold in the sense of a minimal project size transforms a public-good game with an inefficient equilibrium into a coordination game with a set of Pareto-superior equilibria. Thresholds may therefore improve efficiency in the voluntary provision of public goods. In our one-shot e...

  17. Intelligence and Creativity: Over the Threshold Together? (United States)

    Welter, Marisete Maria; Jaarsveld, Saskia; van Leeuwen, Cees; Lachmann, Thomas


    Threshold theory predicts a positive correlation between IQ and creativity scores up to an IQ level of 120 and no correlation above this threshold. Primary school children were tested at beginning (N = 98) and ending (N = 70) of the school year. Participants performed the standard progressive matrices (SPM) and the Test of Creative…

  18. Threshold Concepts, Systems and Learning for Sustainability (United States)

    Sandri, Orana Jade


    This paper presents a framework for understanding the role that systems theory might play in education for sustainability (EfS). It offers a sketch and critique of Land and Meyer's notion of a "threshold concept", to argue that seeing systems as a threshold concept for sustainability is useful for understanding the processes of…

  19. Evaluation of the Detection Threshold of Three ...

    African Journals Online (AJOL)

    A mean count of 39 pigments per microlitre was obtained for these five patients. Both HEXAGON MALARIA and SD-BIOLINE had a detection threshold of 4 pigments per microlitre, while ACCU-STAT MALARIA had 20 pigments per microlitre. This suggests that these three kits have good detection thresholds and could ...

  20. Log canonical thresholds of smooth Fano threefolds

    International Nuclear Information System (INIS)

    Cheltsov, Ivan A; Shramov, Konstantin A


    The complex singularity exponent is a local invariant of a holomorphic function determined by the integrability of fractional powers of the function. The log canonical thresholds of effective Q-divisors on normal algebraic varieties are algebraic counterparts of complex singularity exponents. For a Fano variety, these invariants have global analogues. In the former case, it is the so-called α-invariant of Tian; in the latter case, it is the global log canonical threshold of the Fano variety, which is the infimum of log canonical thresholds of all effective Q-divisors numerically equivalent to the anticanonical divisor. An appendix to this paper contains a proof that the global log canonical threshold of a smooth Fano variety coincides with its α-invariant of Tian. The purpose of the paper is to compute the global log canonical thresholds of smooth Fano threefolds (altogether, there are 105 deformation families of such threefolds). The global log canonical thresholds are computed for every smooth threefold in 64 deformation families, and the global log canonical thresholds are computed for a general threefold in 20 deformation families. Some bounds for the global log canonical thresholds are computed for 14 deformation families. Appendix A is due to J.-P. Demailly.

  1. Estimates of saltation threshold and erosion rates on Mars (United States)

    Iversen, J. D.; White, B. R.; Greeley, R.; Pollack, J. B.


    The Mariner 9 photographs of the Martian surface include many which show crater-associated streaks caused by atmospheric winds. Due to the low density atmosphere of Mars, the wind speeds necessary to move surface particles and thus cause the streaks are apparently very high. The atmospheric-boundary-layer wind tunnel has been used to determine threshold speeds for particles of varying density and diameter and the results for small particles have been extrapolated to estimate somewhat lower threshold speeds on Mars than previous estimates. A series of streak modeling tests is used to derive an erosion-rate correlation function, which is in turn used to estimate erosion rates to the lee of some of the craters on Mars which exhibited time-dependent streak behavior during the mission.

  2. Reaction of oxygen with γ, δ-ethylenic phenylhydrazones. Model reaction of end-group behavior in phenylhydrazine-accelerated oxidation of natural rubber

    International Nuclear Information System (INIS)

    El Hamdaoui, A.; Reyx, D.; Campistron, I.


    An accurate definition of terminal groups of chains in the liquid polymers obtained by the phenylhydrazine-accelerated oxidation of natural rubber is needed. The object of the work was to use model molecules to explore the behavior of γ,δ-ethylenic methylketone phenylhydrazone end-groups in oxidation conditions. We have investigated the synthesis and characterization of models of these hypothetical end-groups, methylketones and phenones 1, their phenylhydrazones 2, the α-(phenyldiazenyl)hydroperoxides 3 resulting from reaction of 2 with oxygen, and the α-(phenyldiazenyl)alcohols 4 as characteristic derivatives of 3 or as models of possible reduced structures in oxidized liquid natural rubber. Three original syntheses of γ,δ-ethylenic ketones were carried out. In the case of γ,δ-ethylenic phenylhydrazones, the oxidation led to the expected α-(phenyldiazenyl)hydroperoxides and to epoxide derivatives of α-(phenyldiazenyl)alcohols 5 and ketones 6. An intramolecular mechanism is proposed. The results are used to predict the possibilities of identification of the corresponding end-groups in liquid rubbers produced in this way. (authors). 16 refs., 12 figs., 3 tabs

  3. Groundwater-fed irrigation impacts spatially distributed temporal scaling behavior of the natural system: a spatio-temporal framework for understanding water management impacts (United States)

    Condon, Laura E.; Maxwell, Reed M.


    Regional scale water management analysis increasingly relies on integrated modeling tools. Much recent work has focused on groundwater-surface water interactions and feedbacks. However, to our knowledge, no study has explicitly considered impacts of management operations on the temporal dynamics of the natural system. Here, we simulate twenty years of hourly moisture dependent, groundwater-fed irrigation using a three-dimensional, fully integrated, hydrologic model (ParFlow-CLM). Results highlight interconnections between irrigation demand, groundwater oscillation frequency and latent heat flux variability not previously demonstrated. Additionally, the three-dimensional model used allows for novel consideration of spatial patterns in temporal dynamics. Latent heat flux and water table depth both display spatial organization in temporal scaling, an important finding given the spatial homogeneity and weak scaling observed in atmospheric forcings. Pumping and irrigation amplify high frequency (sub-annual) variability while attenuating low frequency (inter-annual) variability. Irrigation also intensifies scaling within irrigated areas, essentially increasing temporal memory in both the surface and the subsurface. These findings demonstrate management impacts that extend beyond traditional water balance considerations to the fundamental behavior of the system itself. This is an important step to better understanding groundwater’s role as a buffer for natural variability and the impact that water management has on this capacity.

  4. Groundwater-fed irrigation impacts spatially distributed temporal scaling behavior of the natural system: a spatio-temporal framework for understanding water management impacts

    International Nuclear Information System (INIS)

    Condon, Laura E; Maxwell, Reed M


    Regional scale water management analysis increasingly relies on integrated modeling tools. Much recent work has focused on groundwater–surface water interactions and feedbacks. However, to our knowledge, no study has explicitly considered impacts of management operations on the temporal dynamics of the natural system. Here, we simulate twenty years of hourly moisture dependent, groundwater-fed irrigation using a three-dimensional, fully integrated, hydrologic model (ParFlow-CLM). Results highlight interconnections between irrigation demand, groundwater oscillation frequency and latent heat flux variability not previously demonstrated. Additionally, the three-dimensional model used allows for novel consideration of spatial patterns in temporal dynamics. Latent heat flux and water table depth both display spatial organization in temporal scaling, an important finding given the spatial homogeneity and weak scaling observed in atmospheric forcings. Pumping and irrigation amplify high frequency (sub-annual) variability while attenuating low frequency (inter-annual) variability. Irrigation also intensifies scaling within irrigated areas, essentially increasing temporal memory in both the surface and the subsurface. These findings demonstrate management impacts that extend beyond traditional water balance considerations to the fundamental behavior of the system itself. This is an important step to better understanding groundwater’s role as a buffer for natural variability and the impact that water management has on this capacity. (paper)

  5. Underestimation of pacing threshold as determined by an automatic ventricular threshold testing algorithm. (United States)

    Sauer, William H; Cooper, Joshua M; Lai, Rebecca W; Verdino, Ralph J


    In this case report, we describe markedly different pacing thresholds determined by a manual threshold test and the automatic Ventricular Capture Management algorithm. The discrepancy in pacing threshold values reported was due to the difference in the AV intervals used with the different testing methods. We propose that the differences in right ventricular dimensions with altered diastolic filling periods affected the threshold in this patient with a new passive fixation lead in the right ventricular apex.

  6. A Threshold Continuum for Aeolian Sand Transport (United States)

    Swann, C.; Ewing, R. C.; Sherman, D. J.


    The threshold of motion for aeolian sand transport marks the initial entrainment of sand particles by the force of the wind. This is typically defined and modeled as a singular wind speed for a given grain size and is based on field and laboratory experimental data. However, the definition of threshold varies significantly between these empirical models, largely because the definition is based on visual-observations of initial grain movement. For example, in his seminal experiments, Bagnold defined threshold of motion when he observed that 100% of the bed was in motion. Others have used 50% and lesser values. Differences in threshold models, in turn, result is large errors in predicting the fluxes associated with sand and dust transport. Here we use a wind tunnel and novel sediment trap to capture the fractions of sand in creep, reptation and saltation at Earth and Mars pressures and show that the threshold of motion for aeolian sand transport is best defined as a continuum in which grains progress through stages defined by the proportion of grains in creep and saltation. We propose the use of scale dependent thresholds modeled by distinct probability distribution functions that differentiate the threshold based on micro to macro scale applications. For example, a geologic timescale application corresponds to a threshold when 100% of the bed in motion whereas a sub-second application corresponds to a threshold when a single particle is set in motion. We provide quantitative measurements (number and mode of particle movement) corresponding to visual observations, percent of bed in motion and degrees of transport intermittency for Earth and Mars. Understanding transport as a continuum provides a basis for revaluating sand transport thresholds on Earth, Mars and Titan.

  7. Ecological thresholds as a basis for defining management triggers for National Park Service vital signs: case studies for dryland ecosystems (United States)

    Bowker, Matthew A.; Miller, Mark E.; Belote, R. Travis; Garman, Steven L.


    protection of resources within the range of desired conditions (Cook and others, 2010). The goal of conservation management for natural resources in the U.S. National Park System is to maintain native species and habitat unimpaired for the enjoyment of future generations. Achieving this goal requires, in part, early detection of system change and timely implementation of remediation. The recent National Park Service Inventory and Monitoring program (NPS I&M) was established to provide early warning of declining ecosystem conditions relative to a desired native or reference system (Fancy and others, 2009). To be an effective tool for resource protection, monitoring must be designed to alert managers of impending thresholds so that preventive actions can be taken. This requires an understanding of the ecosystem attributes and processes associated with threshold-type behavior; how these attributes and processes become degraded; and how risks of degradation vary among ecosystems and in relation to environmental factors such as soil properties, climatic conditions, and exposure to stressors. In general, the utility of the threshold concept for long-term monitoring depends on the ability of scientists and managers to detect, predict, and prevent the occurrence of threshold crossings associated with persistent, undesirable shifts among ecosystem states (Briske and others, 2006). Because of the scientific challenges associated with understanding these factors, the application of threshold concepts to monitoring designs has been very limited to date (Groffman and others, 2006). As a case in point, the monitoring efforts across the 32 NPS I&M networks were largely designed with the knowledge that they would not be used to their full potential until the development of a systematic method for understanding threshold dynamics and methods for estimating key attributes of threshold crossings. This report describes and demonstrates a generalized approach that we implemented to formalize

  8. Rejection thresholds in solid chocolate-flavored compound coating. (United States)

    Harwood, Meriel L; Ziegler, Gregory R; Hayes, John E


    Classical detection thresholds do not predict liking, as they focus on the presence or absence of a sensation. Recently however, Prescott and colleagues described a new method, the rejection threshold, where a series of forced choice preference tasks are used to generate a dose-response function to determine hedonically acceptable concentrations. That is, how much is too much? To date, this approach has been used exclusively in liquid foods. Here, we determined group rejection thresholds in solid chocolate-flavored compound coating for bitterness. The influences of self-identified preferences for milk or dark chocolate, as well as eating style (chewers compared to melters) on rejection thresholds were investigated. Stimuli included milk chocolate-flavored compound coating spiked with increasing amounts of sucrose octaacetate, a bitter and generally recognized as safe additive. Paired preference tests (blank compared to spike) were used to determine the proportion of the group that preferred the blank. Across pairs, spiked samples were presented in ascending concentration. We were able to quantify and compare differences between 2 self-identified market segments. The rejection threshold for the dark chocolate preferring group was significantly higher than the milk chocolate preferring group (P= 0.01). Conversely, eating style did not affect group rejection thresholds (P= 0.14), although this may reflect the amount of chocolate given to participants. Additionally, there was no association between chocolate preference and eating style (P= 0.36). Present work supports the contention that this method can be used to examine preferences within specific market segments and potentially individual differences as they relate to ingestive behavior. This work makes use of the rejection threshold method to study market segmentation, extending its use to solid foods. We believe this method has broad applicability to the sensory specialist and product developer by providing a

  9. Behavioral patterns, parity rate and natural infection analysis in anopheline species involved in the transmission of malaria in the northeastern Brazilian Amazon region. (United States)

    Barbosa, Ledayane Mayana Costa; Souto, Raimundo Nonato Picanço; Dos Anjos Ferreira, Ricardo Marcelo; Scarpassa, Vera Margarete


    The characterization of behavioral patterns allows a better understanding of the transmission dynamics and the design of more effective malaria vector control strategies. This study analyzed the behavioral patterns of the Anopheles species of the Coração district situated in the northeast of the Brazilian Amazon region. The behavioral patterns of the anopheline species were measured based on the 36 collection sites of this district from December 2010 to November 2011. Collections of four hours for three consecutive nights each month and four 12-h collections, comprising two in the rainy season and two in the dry season, were performed. Furthermore, to infer the anthropophily and zoophily indexes, four additional four-hour collections were performed. The samples were also evaluated for parity rate and natural infectivity for Plasmodium spp. A total of 1689 anophelines were captured, comprising of nine species and two subgenera (Nyssorhynchus - six species, and Anopheles - three species). Anopheles darlingi was the most abundant and widely distributed species in the area, followed by A. braziliensis and A.marajoara. Anopheles darlingi and A. marajoara were the only species present in the four collections of 12-h, but only A. darlingi showed activity throughout night. Anopheles darlingi was the most anthropophilic species (AI=0.40), but the zoophily index was higher (ZI=0.60), revealing an eclectic and opportunistic behavior. Of the six most frequent species, A. nuneztovari s.l. was the most zoophilic species (ZI=1.00). All captured species showed predominance towards biting in outdoor environments. Anopheles darlingi and A. braziliensis showed multimodal biting peaks, whereas A. marajoara revealed a stable pattern, with the biting peak after sunset. Using the PCR technique, no anopheline was found infected with the malaria parasite. Since A. darlingi and A. marajoara are recognized as important vectors in this region, the district of Coração may be considered as

  10. Threshold behaviour in hydrological systems as (human geo-ecosystems: manifestations, controls, implications

    Directory of Open Access Journals (Sweden)

    M. Sivapalan


    Full Text Available In this paper we review threshold behaviour in environmental systems, which are often associated with the onset of floods, contamination and erosion events, and other degenerative processes. Key objectives of this review are to a suggest indicators for detecting threshold behavior, b discuss their implications for predictability, c distinguish different forms of threshold behavior and their underlying controls, and d hypothesise on possible reasons for why threshold behaviour might occur. Threshold behaviour involves a fast qualitative change of either a single process or the response of a system. For elementary phenomena this switch occurs when boundary conditions (e.g., energy inputs or system states as expressed by dimensionless quantities (e.g. the Reynolds number exceed threshold values. Mixing, water movement or depletion of thermodynamic gradients becomes much more efficient as a result. Intermittency is a very good indicator for detecting event scale threshold behavior in hydrological systems. Predictability of intermittent processes/system responses is inherently low for combinations of systems states and/or boundary conditions that push the system close to a threshold. Post hoc identification of "cause-effect relations" to explain when the system became critical is inherently difficult because of our limited ability to perform observations under controlled identical experimental conditions. In this review, we distinguish three forms of threshold behavior. The first one is threshold behavior at the process level that is controlled by the interplay of local soil characteristics and states, vegetation and the rainfall forcing. Overland flow formation, particle detachment and preferential flow are examples of this. The second form of threshold behaviour is the response of systems of intermediate complexity – e.g., catchment runoff response and sediment yield – governed by the redistribution of water and sediments in space and time

  11. Fatigue crack threshold relevant to stress ratio, crack wake and loading histories

    International Nuclear Information System (INIS)

    Okazaki, Masakazu; Iwasaki, Akira; Kasahara, Naoto


    Fatigue crack propagation behavior was investigated in a low alloy steel which experienced several kind of loading histories. Both the effects of stress ratio, test temperature on the fatigue crack threshold, and the change in the threshold depending on the thermo-mechanical loading histories, were experimentally investigated. It was shown that the thermo-mechanical loading history left its effect along the prior fatigue crack wake resulting in the change of fatigue crack threshold. Some discussions are made on how this type of loading history effect should be treated from engineering point of view. (author)

  12. Applying threshold concepts to conservation management of dryland ecosystems: Case studies on the Colorado Plateau (United States)

    Bowker, Matthew A.; Miller, Mark E.; Garman, Steven L.; Belote, Travis; Guntenspergen, Glenn R.


    Ecosystems may occupy functionally distinct alternative states, some of which are more or less desirable from a management standpoint. Transitions from state to state are usually associated with a particular trigger or sequence of triggers, such as the addition or subtraction of a disturbance. Transitions are often not linear, rather it is common to see an abrupt transition come about even though the trigger increases only incrementally; these are examples of threshold behaviors. An ideal monitoring program, such as the National Park Service’s Inventory and Monitoring Program, would quantify triggers, and be able to inform managers when measurements of a trigger are approaching a threshold so that management action can avoid an unwanted state transition. Unfortunately, both triggers and the threshold points at which state transitions occur are generally only partially known. Using case studies, we advance a general procedure to help identify triggers and estimate where threshold dynamics may occur. Our procedure is as follows: (1) Operationally define the ecosystem type being considered; we suggest that the ecological site concept of the Natural Resource Conservation Service is a useful system, (2) Using all available a priori knowledge to develop a state-and-transition model (STM), which defines possible ecosystem states, plausible transitions among them and likely triggers, (3) Validate the STM by verifying the existence of its states to the greatest degree possible, (4) Use the STM model to identify transitions and triggers likely to be detectable by a monitoring program, and estimate to the greatest degree possible the value of a measurable indicator of a trigger at the point that a state transition is imminent (tipping point), and values that may indicate when management intervention should be considered (assessment points). We illustrate two different methods for attaining these goals using a data-rich case study in Canyonlands National Park, and a data

  13. The Impact of Heterogeneity on Threshold-Limited Social Contagion, and on Crowd Decision-Making (United States)

    Karampourniotis, Panagiotis Dimitrios

    Recent global events and their poor predictability are often attributed to the complexity of the world event dynamics. A key factor generating the turbulence is human diversity. Here, we study the impact of heterogeneity of individuals on opinion formation and emergence of global biases. In the case of opinion formation, we focus on the heterogeneity of individuals' susceptibility to new ideas. In the case of global biases, we focus on the aggregated heterogeneity of individuals in a country. First, to capture the complex nature of social influencing we use a simple but classic model of contagion spreading in complex social systems, namely the threshold model. We investigate numerically and analytically the transition in the behavior of threshold-limited cascades in the presence of multiple initiators as the distribution of thresholds is varied between the two extreme cases of identical thresholds and a uniform distribution. We show that individuals' heterogeneity of susceptibility governs the dynamics, resulting in different sizes of initiators needed for consensus. Furthermore, given the impact of heterogeneity on the cascade dynamics, we investigate selection strategies for accelerating consensus. To this end, we introduce two new selection strategies for Influence Maximization. One of them focuses on finding the balance between targeting nodes which have high resistance to adoptions versus nodes positioned in central spots in networks. The second strategy focuses on the combination of nodes for reaching consensus, by targeting nodes which increase the group's influence. Our strategies outperform other existing strategies regardless of the susceptibility diversity and network degree assortativity. Finally, we study the aggregated biases of humans in a global setting. The emergence of technology and globalization gives raise to the debate on whether the world moves towards becoming flat, a world where preferential attachment does not govern economic growth. By

  14. Interword and intraword pause threshold in writing. (United States)

    Chenu, Florence; Pellegrino, François; Jisa, Harriet; Fayol, Michel


    Writing words in real life involves setting objectives, imagining a recipient, translating ideas into linguistic forms, managing grapho-motor gestures, etc. Understanding writing requires observation of the processes as they occur in real time. Analysis of pauses is one of the preferred methods for accessing the dynamics of writing and is based on the idea that pauses are behavioral correlates of cognitive processes. However, there is a need to clarify what we are observing when studying pause phenomena, as we will argue in the first section. This taken into account, the study of pause phenomena can be considered following two approaches. A first approach, driven by temporality, would define a threshold and observe where pauses, e.g., scriptural inactivity occurs. A second approach, linguistically driven, would define structural units and look for scriptural inactivity at the boundaries of these units or within these units. Taking a temporally driven approach, we present two methods which aim at the automatic identification of scriptural inactivity which is most likely not attributable to grapho-motor management in texts written by children and adolescents using digitizing tablets in association with Eye and Pen (©) (Chesnet and Alamargot, 2005). The first method is purely statistical and is based on the idea that the distribution of pauses exhibits different Gaussian components each of them corresponding to a different type of pause. After having reviewed the limits of this statistical method, we present a second method based on writing dynamics which attempts to identify breaking points in the writing dynamics rather than relying only on pause duration. This second method needs to be refined to overcome the fact that calculation is impossible when there is insufficient data which is often the case when working with young scriptors.

  15. Structured decision making as a conceptual framework to identify thresholds for conservation and management (United States)

    Martin, J.; Runge, M.C.; Nichols, J.D.; Lubow, B.C.; Kendall, W.L.


    Thresholds and their relevance to conservation have become a major topic of discussion in the ecological literature. Unfortunately, in many cases the lack of a clear conceptual framework for thinking about thresholds may have led to confusion in attempts to apply the concept of thresholds to conservation decisions. Here, we advocate a framework for thinking about thresholds in terms of a structured decision making process. The purpose of this framework is to promote a logical and transparent process for making informed decisions for conservation. Specification of such a framework leads naturally to consideration of definitions and roles of different kinds of thresholds in the process. We distinguish among three categories of thresholds. Ecological thresholds are values of system state variables at which small changes bring about substantial changes in system dynamics. Utility thresholds are components of management objectives (determined by human values) and are values of state or performance variables at which small changes yield substantial changes in the value of the management outcome. Decision thresholds are values of system state variables at which small changes prompt changes in management actions in order to reach specified management objectives. The approach that we present focuses directly on the objectives of management, with an aim to providing decisions that are optimal with respect to those objectives. This approach clearly distinguishes the components of the decision process that are inherently subjective (management objectives, potential management actions) from those that are more objective (system models, estimates of system state). Optimization based on these components then leads to decision matrices specifying optimal actions to be taken at various values of system state variables. Values of state variables separating different actions in such matrices are viewed as decision thresholds. Utility thresholds are included in the objectives

  16. Automatic histogram threshold using fuzzy measures. (United States)

    Vieira Lopes, Nuno; Mogadouro do Couto, Pedro A; Bustince, Humberto; Melo-Pinto, Pedro


    In this paper, an automatic histogram threshold approach based on a fuzziness measure is presented. This work is an improvement of an existing method. Using fuzzy logic concepts, the problems involved in finding the minimum of a criterion function are avoided. Similarity between gray levels is the key to find an optimal threshold. Two initial regions of gray levels, located at the boundaries of the histogram, are defined. Then, using an index of fuzziness, a similarity process is started to find the threshold point. A significant contrast between objects and background is assumed. Previous histogram equalization is used in small contrast images. No prior knowledge of the image is required.

  17. Reaction thresholds in doubly special relativity

    International Nuclear Information System (INIS)

    Heyman, Daniel; Major, Seth; Hinteleitner, Franz


    Two theories of special relativity with an additional invariant scale, 'doubly special relativity', are tested with calculations of particle process kinematics. Using the Judes-Visser modified conservation laws, thresholds are studied in both theories. In contrast with some linear approximations, which allow for particle processes forbidden in special relativity, both the Amelino-Camelia and Magueijo-Smolin frameworks allow no additional processes. To first order, the Amelino-Camelia framework thresholds are lowered and the Magueijo-Smolin framework thresholds may be raised or lowered

  18. Digital IP Protection Using Threshold Voltage Control


    Davis, Joseph; Kulkarni, Niranjan; Yang, Jinghua; Dengi, Aykut; Vrudhula, Sarma


    This paper proposes a method to completely hide the functionality of a digital standard cell. This is accomplished by a differential threshold logic gate (TLG). A TLG with $n$ inputs implements a subset of Boolean functions of $n$ variables that are linear threshold functions. The output of such a gate is one if and only if an integer weighted linear arithmetic sum of the inputs equals or exceeds a given integer threshold. We present a novel architecture of a TLG that not only allows a single...

  19. Zn(II, Mn(II and Sr(II Behavior in a Natural Carbonate Reservoir System. Part II: Impact of Geological CO2 Storage Conditions

    Directory of Open Access Journals (Sweden)

    Auffray B.


    Full Text Available Some key points still prevent the full development of geological carbon sequestration in underground formations, especially concerning the assessment of the integrity of such storage. Indeed, the consequences of gas injection on chemistry and petrophysical properties are still much discussed in the scientific community, and are still not well known at either laboratory or field scale. In this article, the results of an experimental study about the mobilization of Trace Elements (TE during CO2 injection in a reservoir are presented. The experimental conditions range from typical storage formation conditions (90 bar, supercritical CO2 to shallower conditions (60 and 30 bar, CO2 as gas phase, and consider the dissolution of the two carbonates, coupled with the sorption of an initial concentration of 10−5 M of Zn(II, and the consequent release in solution of Mn(II and Sr(II. The investigation goes beyond the sole behavior of TE in the storage conditions: it presents the specific behavior of each element with respect to the pressure and the natural carbonate considered, showing that different equilibrium concentrations are to be expected if a fluid with a given concentration of TE leaks to an upper formation. Even though sorption is evidenced, it does not balance the amount of TE released by the dissolution process. The increase in porosity is clearly evidenced as a linear function of the CO2 pressure imposed for the St-Emilion carbonate. For the Lavoux carbonate, this trend is not confirmed by the 90 bar experiment. A preferential dissolution of the bigger family of pores from the preexisting porosity is observed in one of the samples (Lavoux carbonate while the second one (St-Emilion carbonate presents a newly-formed family of pores. Both reacted samples evidence that the pore network evolves toward a tubular network type.

  20. The oscillatory behavior of heated channels: an analysis of the density effect. Part I. The mechanism (non linear analysis). Part II. The oscillations thresholds (linearized analysis); Sur le comportement oscillatoire de canaux chauffes. - Etude theorique de l'effet de densite. 1ere partie: le mecanisme (analyse non lineaire), 2eme partie: seuils d'oscillation (analyse lineaire)

    Energy Technology Data Exchange (ETDEWEB)

    Boure, J. [Commissariat a l' Energie Atomique, Centre d' Etudes Nucleaires de Grenoble, 38 (France)


    The problem of the oscillatory behavior of heated channels is presented in terms of delay-times and a density effect model is proposed to explain the behavior. The density effect is the consequence of the physical relationship between enthalpy and density of the fluid. In the first part non-linear equations are derived from the model in a dimensionless form. A description of the mechanism of oscillations is given, based on the analysis of the equations. An inventory of the governing parameters is established. At this point of the study, some facts in agreement with the experiments can be pointed out. In the second part the start of the oscillatory behavior of heated channels is studied in terms of the density effect. The threshold equations are derived, after linearization of the equations obtained in Part I. They can be solved rigorously by numerical methods to yield: -1) a relation between the describing parameters at the onset of oscillations, and -2) the frequency of the oscillations. By comparing the results predicted by the model to the experimental behavior of actual systems, the density effect is very often shown to be the actual cause of oscillatory behaviors. (author) [French] Premiere partie: mecanisme (equations non linearisees). On expose le probleme du comportement oscillatoire des canaux chauffes en mettant l'accent sur la presence de retards dans le systeme et on propose un modele a 'effet de densite' pour expliquer ce comportement. L'effet de densite est la consequence de la relation physique entre l'enthalpie et la masse volumique du fluide. Les equations non lineaires du schema mathematique correspondant sont etablies et mises sous forme adimensionnelle. L'analyse de ces equations conduit a une description du mecanisme des oscillations. On donne la liste des parametres dont depend le comportement du modele. A ce stade de l'etude, on peut deja relever dans ce comportement plusieurs faits conformes a l

  1. Threshold temperature gradient effect on migration of brine inclusions in salt

    International Nuclear Information System (INIS)

    Pigford, T.H.


    Theories of the migration of brine inclusions in salt were interpreted as simple physical processes, and theories by Russian and US workers were shown to yield the same results. The migration theory was used to predict threshold temperature gradients below which migration of brine inclusions should not occur. The predicted threshold gradients were compared with the temperature gradients expected at the Waste Isolation Pilot Plant in New Mexico. The theory of threshold gradients helps explain the existence of brine inclusions in natural salt deposits

  2. Application of habitat thresholds in conservation: Considerations, limitations, and future directions

    Directory of Open Access Journals (Sweden)

    Yntze van der Hoek


    Full Text Available Habitat thresholds are often interpreted as the minimum required area of habitat, and subsequently promoted as conservation targets in natural resource policies and planning. Unfortunately, several recent reviews and messages of caution on the application of habitat thresholds in conservation have largely fallen on deaf ears, leading to a dangerous oversimplification and generalization of the concept. We highlight the prevalence of oversimplification/over-generalization of results from habitat threshold studies in policy documentation, the consequences of such over-generalization, and directions for habitat threshold studies that have conservation applications without risking overgeneralization. We argue that in order to steer away from misapplication of habitat thresholds in conservation, we should not focus on generalized nominal habitat values (i.e., amounts or percentages of habitat, but on the use of habitat threshold modeling for comparative exercises of area-sensitivity or the identification of environmental dangers. In addition, we should remain focused on understanding the processes and mechanisms underlying species responses to habitat change. Finally, studies could that focus on deriving nominal value threshold amounts should do so only if the thresholds are detailed, species-specific, and translated to conservation targets particular to the study area only.

  3. Fine structures in hearing thresholds and distortion product otoacoustic emissions

    DEFF Research Database (Denmark)

    Hammershøi, Dorte; Ordoñez, Rodrigo Pizarro; Torrente, Marina


    . Distortion product OAEs (DPOAES) are generated in response to a two-tone external stimulus with frequencies f1 and f2. One of the strongest DPOAEs is the component at 2f1-f2. This component is elicited on the basilar membrane in the overlap region of the f1 and f2, close to the f2 place (depending...... of these two components. The result is characterized by a distinct fine structure pattern, and generally doesn't directly reflect the status of the hearing at one point on the basilar membrane. The behavioral threshold, on the other hand, is more directly related to given points along the basilar membrane...

  4. Secure information management using linguistic threshold approach

    CERN Document Server

    Ogiela, Marek R


    This book details linguistic threshold schemes for information sharing. It examines the opportunities of using these techniques to create new models of managing strategic information shared within a commercial organisation or a state institution.

  5. Melanin microcavitation threshold in the near infrared (United States)

    Schmidt, Morgan S.; Kennedy, Paul K.; Vincelette, Rebecca L.; Schuster, Kurt J.; Noojin, Gary D.; Wharmby, Andrew W.; Thomas, Robert J.; Rockwell, Benjamin A.


    Thresholds for microcavitation of isolated bovine and porcine melanosomes were determined using single nanosecond (ns) laser pulses in the NIR (1000 - 1319 nm) wavelength regime. Average fluence thresholds for microcavitation increased non-linearly with increasing wavelength. Average fluence thresholds were also measured for 10-ns pulses at 532 nm, and found to be comparable to visible ns pulse values published in previous reports. Fluence thresholds were used to calculate melanosome absorption coefficients, which decreased with increasing wavelength. This trend was found to be comparable to the decrease in retinal pigmented epithelial (RPE) layer absorption coefficients reported over the same wavelength region. Estimated corneal total intraocular energy (TIE) values were determined and compared to the current and proposed maximum permissible exposure (MPE) safe exposure levels. Results from this study support the proposed changes to the MPE levels.

  6. A prototype threshold Cherenkov counter for DIRAC

    CERN Document Server

    Bragadireanu, M; Cima, E; Dulach, B; Gianotti, P; Guaraldo, C; Iliescu, M A; Lanaro, A; Levi-Sandri, P; Petrascu, C; Girolami, B; Groza, L; Kulikov, A; Kuptsov, A; Topilin, N; Trusov, S


    We have designed, built and tested a gas threshold Cherenkov counter as prototype for a larger counter foreseen for use in the DIRAC experiment, at CERN. We describe the performances of the counter on a test beam.

  7. Recent progress in understanding climate thresholds

    NARCIS (Netherlands)

    Good, Peter; Bamber, Jonathan; Halladay, Kate; Harper, Anna B.; Jackson, Laura C.; Kay, Gillian; Kruijt, Bart; Lowe, Jason A.; Phillips, Oliver L.; Ridley, Jeff; Srokosz, Meric; Turley, Carol; Williamson, Phillip


    This article reviews recent scientific progress, relating to four major systems that could exhibit threshold behaviour: ice sheets, the Atlantic meridional overturning circulation (AMOC), tropical forests and ecosystem responses to ocean acidification. The focus is on advances since the

  8. Cost?effectiveness thresholds: pros and cons


    Bertram, Melanie Y; Lauer, Jeremy A; De Joncheere, Kees; Edejer, Tessa; Hutubessy, Raymond; Kieny, Marie-Paule; Hill, Suzanne R


    Abstract Cost?effectiveness analysis is used to compare the costs and outcomes of alternative policy options. Each resulting cost?effectiveness ratio represents the magnitude of additional health gained per additional unit of resources spent. Cost?effectiveness thresholds allow cost?effectiveness ratios that represent good or very good value for money to be identified. In 2001, the World Health Organization?s Commission on Macroeconomics in Health suggested cost?effectiveness thresholds based...

  9. Estrutura da vegetação e comportamento ingestivo de novilhos em pastagem natural do Rio Grande do Sul Vegetation structure and ingestive behavior of steers in natural pasture in the state of Rio Grande do Sul

    Directory of Open Access Journals (Sweden)

    Juliana Muliterno Thurow


    Full Text Available O experimento foi realizado em uma pastagem natural com o objetivo de avaliar a influência do nível de oferta de forragem sobre a estrutura do pasto e o comportamento ingestivo de bovinos. Foi usado delineamento de blocos completamente casualizados, com quatro níveis de ofertas diárias de forragem (4, 8, 12 e 16 kg de MSFV/100 kg de PV e duas repetições, utilizando-se o método de pastejo contínuo, com taxa de lotação variável. O aumento da oferta de forragem melhorou a participação do estrato superior na forragem disponível e determinou maior altura do estrato inferior. O aumento na altura do estrato inferior ocasionou redução no tempo de pastejo e maior tempo de ruminação no outono, no inverno e na primavera, o que indica melhoria no ambiente pastoril. No entanto, neste tipo de vegetação, o aumento da altura do estrato inferior em maior oferta de forragem não foi suficiente para que a altura atingisse os níveis preconizados para potencializar a ingestão diária de forragem. O aumento da oferta de forragem e da altura do estrato inferior determina resposta linear decrescente do tempo de pastejo, caracterizando ambiente alimentar com maior número de refeições em menor tempo.The experiment was performed in a natural pasture to evaluate the effect of the forage offer level on the pasture structure and ingestive behavior of steers. A completely randomized block design with four daily green forage offer levels (4, 8 12 and 16 kg GFDM/100 kg LW and two replicates was used. The continuous grazing method with variable stocking rate was used. The increasing forage offer enhanced the higher strata frequency and determined higher inferior strata height. The increasing inferior stratum height decreased the grazing time and increased the ruminating time in the autumn, winter and spring, indicating improvements in the grazing environment. However, in this type of vegetation, the increase in height with increasing forage offer was not

  10. Hazard function theory for nonstationary natural hazards (United States)

    Read, Laura K.; Vogel, Richard M.


    Impact from natural hazards is a shared global problem that causes tremendous loss of life and property, economic cost, and damage to the environment. Increasingly, many natural processes show evidence of nonstationary behavior including wind speeds, landslides, wildfires, precipitation, streamflow, sea levels, and earthquakes. Traditional probabilistic analysis of natural hazards based on peaks over threshold (POT) generally assumes stationarity in the magnitudes and arrivals of events, i.e., that the probability of exceedance of some critical event is constant through time. Given increasing evidence of trends in natural hazards, new methods are needed to characterize their probabilistic behavior. The well-developed field of hazard function analysis (HFA) is ideally suited to this problem because its primary goal is to describe changes in the exceedance probability of an event over time. HFA is widely used in medicine, manufacturing, actuarial statistics, reliability engineering, economics, and elsewhere. HFA provides a rich theory to relate the natural hazard event series (X) with its failure time series (T), enabling computation of corresponding average return periods, risk, and reliabilities associated with nonstationary event series. This work investigates the suitability of HFA to characterize nonstationary natural hazards whose POT magnitudes are assumed to follow the widely applied generalized Pareto model. We derive the hazard function for this case and demonstrate how metrics such as reliability and average return period are impacted by nonstationarity and discuss the implications for planning and design. Our theoretical analysis linking hazard random variable X with corresponding failure time series T should have application to a wide class of natural hazards with opportunities for future extensions.

  11. How does precipitation become runoff? Comparison of hydrologic thresholds across hillslope and catchment scales (United States)

    Ross, C.; Ali, G.; Oswald, C. J.; McMillan, H. K.; Walter, K.


    A hydrologic threshold is a critical point in time when runoff behavior rapidly changes, often in response to the activation of specific storage-driven or intensity-driven processes. Hydrologic thresholds can be viewed as characteristic signatures of hydrosystems, which makes them useful for site comparison as long as their presence (or lack thereof) can be evaluated in a standard manner across a range of environments. While several previous studies have successfully identified thresholds at a variety of individual sites, only a limited number have compared dynamics prevailing at the hillslope versus catchment scale, or distinguished the role of storage versus intensity thresholds. The objective of this study was therefore to examine precipitation input thresholds as well as "precipitation minus evapotranspiration" thresholds in environments with contrasted climatic and geographic characteristics. Historical climate and hydrometric datasets were consolidated for one hillslope site located at the Panola Mountain Research Watershed (Southeastern USA) and catchments located in the HJ Andrew's Experimental Forest (Northwestern USA), the Catfish Creek Watershed (Canadian prairies), the Experimental Lakes Area (Canadian boreal ecozone), the Tarrawarra catchment (Australia) and the Mahurangi catchment (New Zealand). Individual precipitation-runoff events were delineated using the newly introduced software HydRun to derive event-specific hydrograph parameters as well surrogate measures of antecedent moisture conditions and evapotranspiration in an automated and consistent manner. Various hydrograph parameters were then plotted against those surrogate measures to detect and evaluate site-specific threshold dynamics. Preliminary results show that a range of threshold shapes (e.g., "hockey stick", heaviside and dirac) were observed across sites. The influence of antecedent precipitation on threshold magnitude and shape also appeared stronger at sites with lower topographic

  12. Watershed safety and quality control by safety threshold method (United States)

    Da-Wei Tsai, David; Mengjung Chou, Caroline; Ramaraj, Rameshprabu; Liu, Wen-Cheng; Honglay Chen, Paris


    Taiwan was warned as one of the most dangerous countries by IPCC and the World Bank. In such an exceptional and perilous island, we would like to launch the strategic research of land-use management on the catastrophe prevention and environmental protection. This study used the watershed management by "Safety Threshold Method" to restore and to prevent the disasters and pollution on island. For the deluge prevention, this study applied the restoration strategy to reduce total runoff which was equilibrium to 59.4% of the infiltration each year. For the sediment management, safety threshold management could reduce the sediment below the equilibrium of the natural sediment cycle. In the water quality issues, the best strategies exhibited the significant total load reductions of 10% in carbon (BOD5), 15% in nitrogen (nitrate) and 9% in phosphorus (TP). We found out the water quality could meet the BOD target by the 50% peak reduction with management. All the simulations demonstrated the safety threshold method was helpful to control the loadings within the safe range of disasters and environmental quality. Moreover, from the historical data of whole island, the past deforestation policy and the mistake economic projects were the prime culprits. Consequently, this study showed a practical method to manage both the disasters and pollution in a watershed scale by the land-use management.

  13. Theoretical study of near-threshold electron-molecule scattering

    International Nuclear Information System (INIS)

    Morrison, M.A.


    We have been engaged in carrying out a foundation study on problems pertaining to near-threshold nuclear excitations in e-H 2 scattering. The primary goals of this study are: to investigate the severity and nature of the anticipated breakdown of the adiabatic-nuclei (AN) approximation, first for rotation only (in the rigid-rotator approximation), and then for vibration; to determine a data base of accurate ab initio cross sections for this important system; to implement and test accurate, computationally-tractable model potentials for exchange and polarization effects; and to begin the exploration of alternative scattering theories for near-threshold collisions. This study has provided a well-defined theoretical context for our future investigations. Second, it has enabled us to identify and quantify several serious problems in the theory of near-threshold electron-molecule scattering that demand attention. And finally, it has led to the development of some of the theoretical and computational apparatus that will form the foundation of future work. In this report, we shall review our progress to date, emphasizing work completed during the current contract year. 17 refs., 5 figs., 1 tab

  14. Natural gas; Gas Natural

    Energy Technology Data Exchange (ETDEWEB)

    Lopes, Carlos A.; Moraes, Claudia C.D. [Eletricidade de Sao Paulo S.A. (ELETROPAULO), Sao Paulo, SP (Brazil); Fonseca, Carlos H.F. [Centrais Eletricas de Santa Catarina S.A., Florianopolis, SC (Brazil); Silva, Clecio Fabricio da; Alves, Ricardo P. [Companhia Paranaense de Energia (COPEL), Curitiba, PR (Brazil); Sposito, Edivaldo Soares; Hulle, Lutero [Espirito Santo Centrais Eletricas S.A. (ESCELSA), Vitoria, ES (Brazil); S. Martins, Icaro da [Centrais Eletricas do Norte do Brasil S.A. (ELETRONORTE), Belem, PA (Brazil); Vilhena, Joao Luiz S. de [Companhia Energetica de Minas Gerais (CEMIG), Belo Horizonte, MG (Brazil); Fagundes, Zaluar Aquino [Companhia Estadual de Energia Eletrica do Estado do Rio Grande do Sul, Porto Alegre, RS (Brazil)


    An increase in the consumption of natural gas in Brazil is an expected fact in what concerns energetic planning. This work presents the existing situation in what concerns natural gas utilization in the main world economies, as well as an analysis of the participation of this fuel among the energy final consumption per sources. The Brazilian consumption of natural gas is also analysed as well as the international agreement between Brazil and Bolivia for natural gas commercialization. Some legal, institutional and political aspects related to natural gas commercialization are also discussed. Finally, several benefits to be brought by the utilization of natural gas are presented 10 refs., 3 tabs.

  15. Bistability threshold inside hysteresis loop of nonlinear fiber Bragg gratings. (United States)

    Yosia, Yosia; Ping, Shum; Chao, Lu


    We show the Cross Phase Modulation (XPM) effect between CW probe that operates in bistability region and strong Gaussian pump in a Fiber Bragg Grating (FBG) by Implicit 4th Order Runge-Kutta Method. The XPM effect results in three unique nonlinear switching behaviors of the probe transmission depending on the pump peak intensity and its Full Width Half Maximum (FWHM) value. From this observation, we offer the FBG three potential nonlinear switching applications in all-optical signal processing domain as: a step-up all-optical switching, an all-optical inverter, and an all-optical limiter. The bistability threshold that determines the nonlinear switching behaviors of probe transmission after Gaussian pump injection is defined numerically and shown to be equivalent to the unstable state inside hysteresis loop.

  16. Tracking of nociceptive thresholds using adaptive psychophysical methods

    NARCIS (Netherlands)

    Doll, Robert; Buitenweg, Jan R.; Meijer, Hil Gaétan Ellart; Veltink, Petrus H.

    Psychophysical thresholds reflect the state of the underlying nociceptive mechanisms. For example, noxious events can activate endogenous analgesic mechanisms that increase the nociceptive threshold. Therefore, tracking thresholds over time facilitates the investigation of the dynamics of these

  17. Evidence accumulator or decision threshold - which cortical mechanism are we observing?

    Directory of Open Access Journals (Sweden)

    Patrick eSimen


    Full Text Available Most psychological models of perceptual decision making are of the accumulation-to-threshold variety. The neural basis of accumulation in parietal and prefrontal cortex is therefore a topic of great interest in neuroscience. In contrast, threshold mechanisms have received less attention, and their neural basis has usually been sought in subcortical structures. Here I analyze a model of a decision threshold that can be implemented in the same cortical areas as evidence accumulators, and whose behavior bears on two open questions in decision neuroscience: 1 When ramping activity is observed in a brain region during decision making, does it reflect evidence accumulation? 2 Are changes in speed-accuracy tradeoffs and response biases more likely to be achieved by changes in thresholds, or in accumulation rates and starting points? The analysis suggests that task-modulated ramping activity, by itself, is weak evidence that a brain area mediates evidence accumulation as opposed to threshold readout; and that signs of modulated accumulation are as likely to indicate threshold adaptation as adaptation of starting points and accumulation rates. These conclusions imply that how thresholds are modeled can dramatically impact accumulator-based interpretations of this data.

  18. Identifying Threshold Concepts for Information Literacy: A Delphi Study

    Directory of Open Access Journals (Sweden)

    Lori Townsend


    Full Text Available This study used the Delphi method to engage expert practitioners on the topic of threshold concepts for information literacy. A panel of experts considered two questions. First, is the threshold concept approach useful for information literacy instruction? The panel unanimously agreed that the threshold concept approach holds potential for information literacy instruction. Second, what are the threshold concepts for information literacy instruction? The panel proposed and discussed over fifty potential threshold concepts, finally settling on six information literacy threshold concepts.

  19. Analytical expression for Risken-Nummedal-Graham-Haken instability threshold in quantum cascade lasers (United States)

    Vukovic, N.; Radovanovic, J.; Milanovic, V.; Boiko, D. L.


    We have obtained a closed-form expression for the threshold of Risken-Nummedal-Graham-Haken (RNGH) multimode instability in a Fabry-P\\'erot (FP) cavity quantum cascade laser (QCL). This simple analytical expression is a versatile tool that can easily be applied in practical situations which require analysis of QCL dynamic behavior and estimation of its second threshold. Our model for a FP cavity laser accounts for the carrier coherence grating and carrier population grating as well as their relaxation due to carrier diffusion. In the model, the RNGH instability threshold is analyzed using a second-order bi-orthogonal perturbation theory and we confirm our analytical solution by a comparison with the numerical simulations. In particular, the model predicts a low second threshold in QCLs. This agrees very well with experimental data available in the literature.

  20. Disaggregated energy consumption and GDP in Taiwan: A threshold co-integration analysis

    International Nuclear Information System (INIS)

    Hu, J.-L.; Lin, C.-H.


    Energy consumption growth is much higher than economic growth for Taiwan in recent years, worsening its energy efficiency. This paper provides a solid explanation by examining the equilibrium relationship between GDP and disaggregated energy consumption under a non-linear framework. The threshold co-integration test developed with asymmetric dynamic adjusting processes proposed by Hansen and Seo [Hansen, B.E., Seo, B., 2002. Testing for two-regime threshold cointegration in vector error-correction models. Journal of Econometrics 110, 293-318.] is applied. Non-linear co-integrations between GDP and disaggregated energy consumptions are confirmed except for oil consumption. The two-regime vector error-correction models (VECM) show that the adjustment process of energy consumption toward equilibrium is highly persistent when an appropriately threshold is reached. There is mean-reverting behavior when the threshold is reached, making aggregate and disaggregated energy consumptions grow faster than GDP in Taiwan

  1. Cost-effectiveness thresholds: pros and cons. (United States)

    Bertram, Melanie Y; Lauer, Jeremy A; De Joncheere, Kees; Edejer, Tessa; Hutubessy, Raymond; Kieny, Marie-Paule; Hill, Suzanne R


    Cost-effectiveness analysis is used to compare the costs and outcomes of alternative policy options. Each resulting cost-effectiveness ratio represents the magnitude of additional health gained per additional unit of resources spent. Cost-effectiveness thresholds allow cost-effectiveness ratios that represent good or very good value for money to be identified. In 2001, the World Health Organization's Commission on Macroeconomics in Health suggested cost-effectiveness thresholds based on multiples of a country's per-capita gross domestic product (GDP). In some contexts, in choosing which health interventions to fund and which not to fund, these thresholds have been used as decision rules. However, experience with the use of such GDP-based thresholds in decision-making processes at country level shows them to lack country specificity and this - in addition to uncertainty in the modelled cost-effectiveness ratios - can lead to the wrong decision on how to spend health-care resources. Cost-effectiveness information should be used alongside other considerations - e.g. budget impact and feasibility considerations - in a transparent decision-making process, rather than in isolation based on a single threshold value. Although cost-effectiveness ratios are undoubtedly informative in assessing value for money, countries should be encouraged to develop a context-specific process for decision-making that is supported by legislation, has stakeholder buy-in, for example the involvement of civil society organizations and patient groups, and is transparent, consistent and fair.

  2. Threshold concepts in finance: conceptualizing the curriculum (United States)

    Hoadley, Susan; Tickle, Leonie; Wood, Leigh N.; Kyng, Tim


    Graduates with well-developed capabilities in finance are invaluable to our society and in increasing demand. Universities face the challenge of designing finance programmes to develop these capabilities and the essential knowledge that underpins them. Our research responds to this challenge by identifying threshold concepts that are central to the mastery of finance and by exploring their potential for informing curriculum design and pedagogical practices to improve student outcomes. In this paper, we report the results of an online survey of finance academics at multiple institutions in Australia, Canada, New Zealand, South Africa and the United Kingdom. The outcomes of our research are recommendations for threshold concepts in finance endorsed by quantitative evidence, as well as a model of the finance curriculum incorporating finance, modelling and statistics threshold concepts. In addition, we draw conclusions about the application of threshold concept theory supported by both quantitative and qualitative evidence. Our methodology and findings have general relevance to the application of threshold concept theory as a means to investigate and inform curriculum design and delivery in higher education.

  3. Natural games

    International Nuclear Information System (INIS)

    Anttila, Jani; Annila, Arto


    A course of a game is formulated as a physical process that will consume free energy in the least time. Accordingly, the rate of entropy increase is the payoff function that will subsume all forms of free energy that motivate diverse decisions. Also other concepts of game theory are related to their profound physical counterparts. When the physical portrayal of behavior is mathematically analyzed, the course of a game is found to be inherently unpredictable because each move affects motives in the future. Despite the non-holonomic character of the natural process, the objective of consuming free energy in the least time will direct an extensive-form game toward a Lyapunov-stable point that satisfies the minimax theorem. -- Highlights: → Behavior in the context of game theory is described as a natural process. → The rate of entropy increase, derived from statistical physics of open systems, is identified as the payoff function. → Entropy as the payoff function also clarifies motives of collaboration and subjective nature of decision making. → Evolutionary equation of motion that accounts for the course of a game is inherently unpredictable.

  4. The potential effect of age on the natural behavior of bladder cancer: Does urothelial cell carcinoma progress differently in various age groups? (United States)

    Gunlusoy, Bulent; Ceylan, Yasin; Degirmenci, Tansu; Aydogdu, Ozgu; Bozkurt, Ibrahim Halil; Yonguc, Tarik; Sen, Volkan; Kozacioglu, Zafer


    We aimed to evaluate the potential effect of age on the natural behavior of bladder cancer and to compare these findings between different age groups. The clinical and pathologic data of 239 patients treated at our institution between 1994 and 2014 were analyzed. The patients were classified into three groups according to age: ≤ 40 years (Group 1), 41-59 years (Group 2), and ≥ 60 years (Group 3). The following data were collected: characteristics of the patients, initial pathological findings after transurethral resection, tumor stage and grade, tumor size and multiplicity, and disease recurrence and progression. The mean age of the patients at initial diagnosis was 34.2±5.5 years, 53±5.1 years, and 71.1±7 years in Groups 1, 2, and 3, respectively. There were 207 (86.6%) patients with nonmuscle-invasive urothelial bladder cancer and 32 (13.4%) patients with muscle-invasive disease. Tumor recurrence was significantly lower in Group 1 than in Group 2 (p=0.001) and Group 3 (p=0.001). Although the time to tumor recurrence was significantly different between the three groups (p=0.001), no significant difference was noted in the time to progression (p=0.349). Patients with urothelial cancer younger than 40 years tend to have single and small tumors. The tumor recurrence rate is lower in the younger age group, but tumor progression is similar in older and younger patients. Therefore, the findings indicate that clinicians should be careful when assessing the invasiveness of urothelial tumors in younger patients and start treatment as soon as possible. Copyright © 2016. Published by Elsevier Taiwan.

  5. A two-step framework for over-threshold modelling of environmental extremes (United States)

    Bernardara, P.; Mazas, F.; Kergadallan, X.; Hamm, L.


    The evaluation of the probability of occurrence of extreme natural events is important for the protection of urban areas, industrial facilities and others. Traditionally, the extreme value theory (EVT) offers a valid theoretical framework on this topic. In an over-threshold modelling (OTM) approach, Pickands' theorem, (Pickands, 1975) states that, for a sample composed by independent and identically distributed (i.i.d.) values, the distribution of the data exceeding a given threshold converges through a generalized Pareto distribution (GPD). Following this theoretical result, the analysis of realizations of environmental variables exceeding a threshold spread widely in the literature. However, applying this theorem to an auto-correlated time series logically involves two successive and complementary steps: the first one is required to build a sample of i.i.d. values from the available information, as required by the EVT; the second to set the threshold for the optimal convergence toward the GPD. In the past, the same threshold was often employed both for sampling observations and for meeting the hypothesis of extreme value convergence. This confusion can lead to an erroneous understanding of methodologies and tools available in the literature. This paper aims at clarifying the conceptual framework involved in threshold selection, reviewing the available methods for the application of both steps and illustrating it with a double threshold approach.

  6. Regression Discontinuity Designs Based on Population Thresholds

    DEFF Research Database (Denmark)

    Eggers, Andrew C.; Freier, Ronny; Grembi, Veronica

    ) to measure the effects of these threshold-based policies on political and economic outcomes. Using evidence from France, Germany, and Italy, we highlight two common pitfalls that arise in exploiting population-based policies (confounded treatment and sorting) and we provide guidance for detecting......In many countries, important features of municipal government (such as the electoral system, mayors' salaries, and the number of councillors) depend on whether the municipality is above or below arbitrary population thresholds. Several papers have used a regression discontinuity design (RDD...... and addressing these pitfalls. Even when these problems are present, population-threshold RDD may be the best available research design for studying the effects of certain policies and political institutions....

  7. Effects of pulse duration on magnetostimulation thresholds

    Energy Technology Data Exchange (ETDEWEB)

    Saritas, Emine U., E-mail: [Department of Bioengineering, University of California, Berkeley, Berkeley, California 94720-1762 (United States); Department of Electrical and Electronics Engineering, Bilkent University, Bilkent, Ankara 06800 (Turkey); National Magnetic Resonance Research Center (UMRAM), Bilkent University, Bilkent, Ankara 06800 (Turkey); Goodwill, Patrick W. [Department of Bioengineering, University of California, Berkeley, Berkeley, California 94720-1762 (United States); Conolly, Steven M. [Department of Bioengineering, University of California, Berkeley, Berkeley, California 94720-1762 (United States); Department of EECS, University of California, Berkeley, California 94720-1762 (United States)


    Purpose: Medical imaging techniques such as magnetic resonance imaging and magnetic particle imaging (MPI) utilize time-varying magnetic fields that are subject to magnetostimulation limits, which often limit the speed of the imaging process. Various human-subject experiments have studied the amplitude and frequency dependence of these thresholds for gradient or homogeneous magnetic fields. Another contributing factor was shown to be number of cycles in a magnetic pulse, where the thresholds decreased with longer pulses. The latter result was demonstrated on two subjects only, at a single frequency of 1.27 kHz. Hence, whether the observed effect was due to the number of cycles or due to the pulse duration was not specified. In addition, a gradient-type field was utilized; hence, whether the same phenomenon applies to homogeneous magnetic fields remained unknown. Here, the authors investigate the pulse duration dependence of magnetostimulation limits for a 20-fold range of frequencies using homogeneous magnetic fields, such as the ones used for the drive field in MPI. Methods: Magnetostimulation thresholds were measured in the arms of six healthy subjects (age: 27 ± 5 yr). Each experiment comprised testing the thresholds at eight different pulse durations between 2 and 125 ms at a single frequency, which took approximately 30–40 min/subject. A total of 34 experiments were performed at three different frequencies: 1.2, 5.7, and 25.5 kHz. A solenoid coil providing homogeneous magnetic field was used to induce stimulation, and the field amplitude was measured in real time. A pre-emphasis based pulse shaping method was employed to accurately control the pulse durations. Subjects reported stimulation via a mouse click whenever they felt a twitching/tingling sensation. A sigmoid function was fitted to the subject responses to find the threshold at a specific frequency and duration, and the whole procedure was repeated at all relevant frequencies and pulse durations

  8. Smaller Fixation Target Size Is Associated with More Stable Fixation and Less Variance in Threshold Sensitivity.

    Directory of Open Access Journals (Sweden)

    Kazunori Hirasawa

    Full Text Available The aims of this randomized observational case control study were to quantify fixation behavior during standard automated perimetry (SAP with different fixation targets and to evaluate the relationship between fixation behavior and threshold variability at each test point in healthy young participants experienced with perimetry. SAP was performed on the right eyes of 29 participants using the Octopus 900 perimeter, program 32, dynamic strategy. The fixation targets of Point, Cross, and Ring were used for SAP. Fixation behavior was recorded using a wearable eye-tracking glass. All participants underwent SAP twice with each fixation target in a random fashion. Fixation behavior was quantified by calculating the bivariate contour ellipse area (BCEA and the frequency of deviation from the fixation target. The BCEAs (deg2 of Point, Cross, and Ring targets were 1.11, 1.46, and 2.02, respectively. In all cases, BCEA increased significantly with increasing fixation target size (p < 0.05. The logarithmic value of BCEA demonstrated the same tendency (p < 0.05. A positive correlation was identified between fixation behavior and threshold variability for the Point and Cross targets (ρ = 0.413-0.534, p < 0.05. Fixation behavior increased with increasing fixation target size. Moreover, a larger fixation behavior tended to be associated with a higher threshold variability. A small fixation target is recommended during the visual field test.

  9. Social contagion with degree-dependent thresholds (United States)

    Lee, Eun; Holme, Petter


    We investigate opinion spreading by a threshold model in a situation in which the influence of people is heterogeneously distributed. We assume that there is a coupling between the influence of an individual (measured by the out-degree) and the threshold for accepting a new opinion or habit. We find that if the coupling is strongly positive, the final state of the system will be a mix of different opinions. Otherwise, it will converge to a consensus state. This phenomenon cannot simply be explained as a phase transition, but it is a combined effect of mechanisms and their relative dominance in different regions of parameter space.

  10. Thresholds in Xeric Hydrology and Biogeochemistry (United States)

    Meixner, T.; Brooks, P. D.; Simpson, S. C.; Soto, C. D.; Yuan, F.; Turner, D.; Richter, H.


    Due to water limitation, thresholds in hydrologic and biogeochemical processes are common in arid and semi-arid systems. Some of these thresholds such as those focused on rainfall runoff relationships have been well studied. However to gain a full picture of the role that thresholds play in driving the hydrology and biogeochemistry of xeric systems a full view of the entire array of processes at work is needed. Here a walk through the landscape of xeric systems will be conducted illustrating the powerful role of hydrologic thresholds on xeric system biogeochemistry. To understand xeric hydro-biogeochemistry two key ideas need to be focused on. First, it is important to start from a framework of reaction and transport. Second an understanding of the temporal and spatial components of thresholds that have a large impact on hydrologic and biogeochemical fluxes needs to be offered. In the uplands themselves episodic rewetting and drying of soils permits accelerated biogeochemical processing but also more gradual drainage of water through the subsurface than expected in simple conceptions of biogeochemical processes. Hydrologic thresholds (water content above hygroscopic) results in a stop start nutrient spiral of material across the landscape since runoff connecting uplands to xeric perennial riparian is episodic and often only transports materials a short distance (100's of m). This episodic movement results in important and counter-intuitive nutrient inputs to riparian zones but also significant processing and uptake of nutrients. The floods that transport these biogeochemicals also result in significant input to riparian groundwater and may be key to sustaining these critical ecosystems. Importantly the flood driven recharge process itself is a threshold process dependent on flood characteristics (floods greater than 100 cubic meters per second) and antecedent conditions (losing to near neutral gradients). Floods also appear to influence where arid and semi

  11. Color image Segmentation using automatic thresholding techniques

    International Nuclear Information System (INIS)

    Harrabi, R.; Ben Braiek, E.


    In this paper, entropy and between-class variance based thresholding methods for color images segmentation are studied. The maximization of the between-class variance (MVI) and the entropy (ME) have been used as a criterion functions to determine an optimal threshold to segment images into nearly homogenous regions. Segmentation results from the two methods are validated and the segmentation sensitivity for the test data available is evaluated, and a comparative study between these methods in different color spaces is presented. The experimental results demonstrate the superiority of the MVI method for color image segmentation.

  12. Modeling DPOAE input/output function compression: comparisons with hearing thresholds. (United States)

    Bhagat, Shaum P


    Basilar membrane input/output (I/O) functions in mammalian animal models are characterized by linear and compressed segments when measured near the location corresponding to the characteristic frequency. A method of studying basilar membrane compression indirectly in humans involves measuring distortion-product otoacoustic emission (DPOAE) I/O functions. Previous research has linked compression estimates from behavioral growth-of-masking functions to hearing thresholds. The aim of this study was to compare compression estimates from DPOAE I/O functions and hearing thresholds at 1 and 2 kHz. A prospective correlational research design was performed. The relationship between DPOAE I/O function compression estimates and hearing thresholds was evaluated with Pearson product-moment correlations. Normal-hearing adults (n = 16) aged 22-42 yr were recruited. DPOAE I/O functions (L₂ = 45-70 dB SPL) and two-interval forced-choice hearing thresholds were measured in normal-hearing adults. A three-segment linear regression model applied to DPOAE I/O functions supplied estimates of compression thresholds, defined as breakpoints between linear and compressed segments and the slopes of the compressed segments. Pearson product-moment correlations between DPOAE compression estimates and hearing thresholds were evaluated. A high correlation between DPOAE compression thresholds and hearing thresholds was observed at 2 kHz, but not at 1 kHz. Compression slopes also correlated highly with hearing thresholds only at 2 kHz. The derivation of cochlear compression estimates from DPOAE I/O functions provides a means to characterize basilar membrane mechanics in humans and elucidates the role of compression in tone detection in the 1-2 kHz frequency range. American Academy of Audiology.

  13. Comparison between intensity- duration thresholds and cumulative rainfall thresholds for the forecasting of landslide (United States)

    Lagomarsino, Daniela; Rosi, Ascanio; Rossi, Guglielmo; Segoni, Samuele; Catani, Filippo


    This work makes a quantitative comparison between the results of landslide forecasting obtained using two different rainfall threshold models, one using intensity-duration thresholds and the other based on cumulative rainfall thresholds in an area of northern Tuscany of 116 km2. The first methodology identifies rainfall intensity-duration thresholds by means a software called MaCumBA (Massive CUMulative Brisk Analyzer) that analyzes rain-gauge records, extracts the intensities (I) and durations (D) of the rainstorms associated with the initiation of landslides, plots these values on a diagram, and identifies thresholds that define the lower bounds of the I-D values. A back analysis using data from past events can be used to identify the threshold conditions associated with the least amount of false alarms. The second method (SIGMA) is based on the hypothesis that anomalous or extreme values of rainfall are responsible for landslide triggering: the statistical distribution of the rainfall series is analyzed, and multiples of the standard deviation (σ) are used as thresholds to discriminate between ordinary and extraordinary rainfall events. The name of the model, SIGMA, reflects the central role of the standard deviations in the proposed methodology. The definition of intensity-duration rainfall thresholds requires the combined use of rainfall measurements and an inventory of dated landslides, whereas SIGMA model can be implemented using only rainfall data. These two methodologies were applied in an area of 116 km2 where a database of 1200 landslides was available for the period 2000-2012. The results obtained are compared and discussed. Although several examples of visual comparisons between different intensity-duration rainfall thresholds are reported in the international literature, a quantitative comparison between thresholds obtained in the same area using different techniques and approaches is a relatively undebated research topic.

  14. In search of 'low health literacy': threshold vs. gradient effect of literacy on health status and mortality. (United States)

    Wolf, Michael S; Feinglass, Joseph; Thompson, Jason; Baker, David W


    Studies have demonstrated significant associations between limited literacy and health outcomes. Yet differences in literacy measurement and the cutoffs used for analysis have made it difficult to fully understand the relationship between literacy and health across the entire spectrum of literacy (i.e., whether the relationship is continuous and graded or whether a threshold exists below which literacy is independently associated with health). To analyze this question, we re-examined the relationship between literacy, baseline physical functioning and mental health, and all-cause mortality for a cohort of 3260 US community-dwelling elderly who were interviewed in 1997 to determine demographics, socioeconomic status, chronic conditions, self-reported physical and mental health (SF-36 subscales), health behaviors, and literacy based upon the Short Test of Functional Health Literacy in Adults (S-TOFHLA). All-cause mortality was determined using data from the US National Death Index through 2003. Seven categories of S-TOFHLA literacy scores were created and used in this analysis instead of the existing three categories identified with the measure. In multivariate analyses, a continuous, graded relationship between literacy and baseline physical functioning was identified. However, participants scoring below the third literacy category had significantly worse mental health compared to the highest literacy category, displaying a notable threshold. Finally, all six literacy categories were significantly associated with greater all-cause mortality risk compared to the highest literacy category, but again there was a marked threshold below the third category at which the adjusted mortality rate significantly increased compared to all other categories. We conclude that the nature of the relationship between literacy and health may vary depending upon the outcome under examination. Copyright 2010. Published by Elsevier Ltd.

  15. Speech-in-Noise Tests and Supra-threshold Auditory Evoked Potentials as Metrics for Noise Damage and Clinical Trial Outcome Measures. (United States)

    Le Prell, Colleen G; Brungart, Douglas S


    In humans, the accepted clinical standards for detecting hearing loss are the behavioral audiogram, based on the absolute detection threshold of pure-tones, and the threshold auditory brainstem response (ABR). The audiogram and the threshold ABR are reliable and sensitive measures of hearing thresholds in human listeners. However, recent results from noise-exposed animals demonstrate that noise exposure can cause substantial neurodegeneration in the peripheral auditory system without degrading pure-tone audiometric thresholds. It has been suggested that clinical measures of auditory performance conducted with stimuli presented above the detection threshold may be more sensitive than the behavioral audiogram in detecting early-stage noise-induced hearing loss in listeners with audiometric thresholds within normal limits. Supra-threshold speech-in-noise testing and supra-threshold ABR responses are reviewed here, given that they may be useful supplements to the behavioral audiogram for assessment of possible neurodegeneration in noise-exposed listeners. Supra-threshold tests may be useful for assessing the effects of noise on the human inner ear, and the effectiveness of interventions designed to prevent noise trauma. The current state of the science does not necessarily allow us to define a single set of best practice protocols. Nonetheless, we encourage investigators to incorporate these metrics into test batteries when feasible, with an effort to standardize procedures to the greatest extent possible as new reports emerge.

  16. Breakup threshold anomaly in the elastic scattering of 6Li on 27Al

    International Nuclear Information System (INIS)

    Figueira, J. M.; Niello, J. O. Fernandez; Abriola, D.; Arazi, A.; Capurro, O. A.; Barbara, E. de; Marti, G. V.; Heimann, D. Martinez; Negri, A. E.; Pacheco, A. J.; Padron, I.; Gomes, P. R. S.; Lubian, J.; Correa, T.; Paes, B.


    Elastic scattering of the weakly bound 6 Li on 27 Al was measured at near-barrier energies. The data analysis was performed using a Woods-Saxon shape optical potential and also using the double-folding Sao Paulo potential. The results show the presence of the breakup threshold anomaly (BTA), an anomalous behavior when compared with the scattering of tightly bound nuclei. This behavior is attributed to a repulsive polarization potential produced by the coupling to the continuum breakup states

  17. On the two steps threshold selection for over-threshold modelling of extreme events (United States)

    Bernardara, Pietro; Mazas, Franck; Weiss, Jerome; Andreewsky, Marc; Kergadallan, Xavier; Benoit, Michel; Hamm, Luc


    The estimation of the probability of occurrence of extreme events is traditionally achieved by fitting a probability distribution on a sample of extreme observations. In particular, the extreme value theory (EVT) states that values exceeding a given threshold converge through a Generalized Pareto Distribution (GPD) if the original sample is composed of independent and identically distributed values. However, the temporal series of sea and ocean variables usually show strong temporal autocorrelation. Traditionally, in order to select independent events for the following statistical analysis, the concept of a physical threshold is introduced: events that excess that threshold are defined as "extreme events". This is the so-called "Peak Over a Threshold (POT)" sampling, widely spread in the literature and currently used for engineering applications among many others. In the past, the threshold for the statistical sampling of extreme values asymptotically convergent toward GPD and the threshold for the physical selection of independent extreme events were confused, as the same threshold was used for both sampling data and to meet the hypothesis of extreme value convergence, leading to some incoherencies. In particular, if the two steps are performed simultaneously, the number of peaks over the threshold can increase but also decrease when the threshold decreases. This is logic in a physical point of view, since the definition of the sample of "extreme events" changes, but is not coherent with the statistical theory. We introduce a two-steps threshold selection for over-threshold modelling, aiming to discriminate (i) a physical threshold for the selection of extreme and independent events, and (ii) a statistical threshold for the optimization of the coherence with the hypothesis of the EVT. The former is a physical events identification procedure (also called "declustering") aiming at selecting independent extreme events. The latter is a purely statistical optimization

  18. Mesoscale spatial variability in seawater cavitation thresholds (United States)

    Mel'nikov, N. P.; Elistratov, V. P.


    The paper presents the spatial variability of cavitation thresholds and some hydrological and hydrochemical parameters of seawater in the interfrontal zone of the Pacific Subarctic Front, in the Drake Passage, and in the equatorial part of the Pacific Ocean, measured in the near-surface layer to a depth of 70 m.

  19. Intraoperative transfusion threshold and tissue oxygenation

    DEFF Research Database (Denmark)

    Nielsen, K; Dahl, B; Johansson, P I


    Transfusion with allogeneic red blood cells (RBCs) may be needed to maintain oxygen delivery during major surgery, but the appropriate haemoglobin (Hb) concentration threshold has not been well established. We hypothesised that a higher level of Hb would be associated with improved subcutaneous...

  20. Threshold Concepts in Finance: Conceptualizing the Curriculum (United States)

    Hoadley, Susan; Tickle, Leonie; Wood, Leigh N.; Kyng, Tim


    Graduates with well-developed capabilities in finance are invaluable to our society and in increasing demand. Universities face the challenge of designing finance programmes to develop these capabilities and the essential knowledge that underpins them. Our research responds to this challenge by identifying threshold concepts that are central to…

  1. Heritability estimates derived from threshold analyses for ...

    African Journals Online (AJOL)


    Abstract. The object of this study was to estimate heritabilities and sire breeding values for stayability and reproductive traits in a composite multibreed beef cattle herd using a threshold model. A GFCAT set of programmes was used to analyse reproductive data. Heritabilities and product-moment correlations between.

  2. Design of Threshold Controller Based Chaotic Circuits

    DEFF Research Database (Denmark)

    Mohamed, I. Raja; Murali, K.; Sinha, Sudeshna


    We propose a very simple implementation of a second-order nonautonomous chaotic oscillator, using a threshold controller as the only source of nonlinearity. We demonstrate the efficacy and simplicity of our design through numerical and experimental results. Further, we show that this approach...

  3. Grid - a fast threshold tracking procedure

    DEFF Research Database (Denmark)

    Fereczkowski, Michal; Dau, Torsten; MacDonald, Ewen


    A new procedure, called “grid”, is evaluated that allows rapid acquisition of threshold curves for psychophysics and, in particular, psychoacoustic, experiments. In this method, the parameterresponse space is sampled in two dimensions within a single run. This allows the procedure to focus more e...

  4. Atherogenic Risk Factors and Hearing Thresholds

    DEFF Research Database (Denmark)

    Frederiksen, Thomas Winther; Ramlau-Hansen, Cecilia Høst; Stokholm, Zara Ann


    The objective of this study was to evaluate the influence of atherogenic risk factors on hearing thresholds. In a cross-sectional study we analyzed data from a Danish survey in 2009-2010 on physical and psychological working conditions. The study included 576 white- and blue-collar workers from c...

  5. Identification of Threshold Concepts for Biochemistry (United States)

    Loertscher, Jennifer; Green, David; Lewis, Jennifer E.; Lin, Sara; Minderhout, Vicky


    Threshold concepts (TCs) are concepts that, when mastered, represent a transformed understanding of a discipline without which the learner cannot progress. We have undertaken a process involving more than 75 faculty members and 50 undergraduate students to identify a working list of TCs for biochemistry. The process of identifying TCs for…

  6. Determining lower threshold concentrations for synergistic effects

    DEFF Research Database (Denmark)

    Bjergager, Maj-Britt Andersen; Dalhoff, Kristoffer; Kretschmann, Andreas


    which proven synergists cease to act as synergists towards the aquatic crustacean Daphnia magna. To do this, we compared several approaches and test-setups to evaluate which approach gives the most conservative estimate for the lower threshold for synergy for three known azole synergists. We focus.......619±8.555μgL(-1)) and 0.122±0.0417μM (40.236±13.75μgL(-1)), respectively, in the 14-days tests. Testing synergy in relation to concentration addition provided the most conservative values. The threshold values for the vertical assessments in tests where the two could be compared were in general 1.2 to 4.......7 fold higher than the horizontal assessments. Using passive dosing rather than dilution series or spiking did not lower the threshold significantly. Below the threshold for synergy, slight antagony could often be observed. This is most likely due to induction of enzymes active in metabolization of alpha...

  7. Microplastic effect thresholds for freshwater benthic macroinvertebrates

    NARCIS (Netherlands)

    Redondo Hasselerharm, P.E.; Dede Falahudin, Dede; Peeters, E.T.H.M.; Koelmans, A.A.


    Now that microplastics have been detected in lakes, rivers and estuaries all over the globe, evaluating their effects on biota has become an urgent research priority. This is the first study that aims at determining the effect thresholds for a battery of six freshwater benthic macroinvertebrates

  8. Distribution of sensory taste thresholds for phenylthiocarbamide ...

    African Journals Online (AJOL)

    The ability to taste Phenylthiocarbamide (PTC), a bitter organic compound has been described as a bimodal autosomal trait in both genetic and anthropological studies. This study is based on the ability of a person to taste PTC. The present study reports the threshold distribution of PTC taste sensitivity among some Muslim ...

  9. A low-threshold erbium glass minilaser (United States)

    Gapontsev, V. P.; Gromov, A. K.; Izyneev, A. A.; Sadovskii, P. I.; Stavrov, A. A.


    Minilasers emitting in the 1.54-micron region with an emission threshold less than 5 J and efficiency up to 1.7 percent have been constructed using a Cr-Y-Er laser glass, LGS-Kh. Under repetitively-pulsed operation, an average lasing power of 0.7 W and a pulse repetition rate of 7 Hz have been achieved.

  10. Thresholding methods for PET imaging: A review

    International Nuclear Information System (INIS)

    Dewalle-Vignion, A.S.; Betrouni, N.; Huglo, D.; Vermandel, M.; Dewalle-Vignion, A.S.; Hossein-Foucher, C.; Huglo, D.; Vermandel, M.; Dewalle-Vignion, A.S.; Hossein-Foucher, C.; Huglo, D.; Vermandel, M.; El Abiad, A.


    This work deals with positron emission tomography segmentation methods for tumor volume determination. We propose a state of art techniques based on fixed or adaptive threshold. Methods found in literature are analysed with an objective point of view on their methodology, advantages and limitations. Finally, a comparative study is presented. (authors)

  11. Low-threshold conical microcavity dye lasers

    DEFF Research Database (Denmark)

    Grossmann, Tobias; Schleede, Simone; Hauser, Mario


    element simulations confirm that lasing occurs in whispering gallery modes which corresponds well to the measured multimode laser-emission. The effect of dye concentration on lasing threshold and lasing wavelength is investigated and can be explained using a standard dye laser model....

  12. Classification error of the thresholded independence rule

    DEFF Research Database (Denmark)

    Bak, Britta Anker; Fenger-Grøn, Morten; Jensen, Jens Ledet

    We consider classification in the situation of two groups with normally distributed data in the ‘large p small n’ framework. To counterbalance the high number of variables we consider the thresholded independence rule. An upper bound on the classification error is established which is taylored...

  13. The acoustic reflex threshold in aging ears. (United States)

    Silverman, C A; Silman, S; Miller, M H


    This study investigates the controversy regarding the influence of age on the acoustic reflex threshold for broadband noise, 500-, 1000-, 2000-, and 4000-Hz activators between Jerger et al. [Mono. Contemp. Audiol. 1 (1978)] and Jerger [J. Acoust. Soc. Am. 66 (1979)] on the one hand and Silman [J. Acoust. Soc. Am. 66 (1979)] and others on the other. The acoustic reflex thresholds for broadband noise, 500-, 1000-, 2000-, and 4000-Hz activators were evaluated under two measurement conditions. Seventy-two normal-hearing ears were drawn from 72 subjects ranging in age from 20-69 years. The results revealed that age was correlated with the acoustic reflex threshold for BBN activator but not for any of the tonal activators; the correlation was stronger under the 1-dB than under the 5-dB measurement condition. Also, the mean acoustic reflex thresholds for broadband noise activator were essentially similar to those reported by Jerger et al. (1978) but differed from those obtained in this study under the 1-dB measurement condition.

  14. Distance Discrimination Thresholds During Flight Simulation in a Maritime Environment (United States)


    UNCLASSIFIED Distance Discrimination Thresholds During Flight Simulation in a Maritime Environment Jessica Parker Air Operations...Distance Discrimination Thresholds During Flight Simulation in a Maritime Environment Executive Summary The Aeronautical Design Standard...position to be perceived. This minimum distance was defined as the distance discrimination threshold. For both high and low sea states, the thresholds

  15. Cost–effectiveness thresholds: pros and cons (United States)

    Lauer, Jeremy A; De Joncheere, Kees; Edejer, Tessa; Hutubessy, Raymond; Kieny, Marie-Paule; Hill, Suzanne R


    Abstract Cost–effectiveness analysis is used to compare the costs and outcomes of alternative policy options. Each resulting cost–effectiveness ratio represents the magnitude of additional health gained per additional unit of resources spent. Cost–effectiveness thresholds allow cost–effectiveness ratios that represent good or very good value for money to be identified. In 2001, the World Health Organization’s Commission on Macroeconomics in Health suggested cost–effectiveness thresholds based on multiples of a country’s per-capita gross domestic product (GDP). In some contexts, in choosing which health interventions to fund and which not to fund, these thresholds have been used as decision rules. However, experience with the use of such GDP-based thresholds in decision-making processes at country level shows them to lack country specificity and this – in addition to uncertainty in the modelled cost–effectiveness ratios – can lead to the wrong decision on how to spend health-care resources. Cost–effectiveness information should be used alongside other considerations – e.g. budget impact and feasibility considerations – in a transparent decision-making process, rather than in isolation based on a single threshold value. Although cost–effectiveness ratios are undoubtedly informative in assessing value for money, countries should be encouraged to develop a context-specific process for decision-making that is supported by legislation, has stakeholder buy-in, for example the involvement of civil society organizations and patient groups, and is transparent, consistent and fair. PMID:27994285

  16. Multimodal distribution of human cold pain thresholds. (United States)

    Lötsch, Jörn; Dimova, Violeta; Lieb, Isabel; Zimmermann, Michael; Oertel, Bruno G; Ultsch, Alfred


    It is assumed that different pain phenotypes are based on varying molecular pathomechanisms. Distinct ion channels seem to be associated with the perception of cold pain, in particular TRPM8 and TRPA1 have been highlighted previously. The present study analyzed the distribution of cold pain thresholds with focus at describing the multimodality based on the hypothesis that it reflects a contribution of distinct ion channels. Cold pain thresholds (CPT) were available from 329 healthy volunteers (aged 18 - 37 years; 159 men) enrolled in previous studies. The distribution of the pooled and log-transformed threshold data was described using a kernel density estimation (Pareto Density Estimation (PDE)) and subsequently, the log data was modeled as a mixture of Gaussian distributions using the expectation maximization (EM) algorithm to optimize the fit. CPTs were clearly multi-modally distributed. Fitting a Gaussian Mixture Model (GMM) to the log-transformed threshold data revealed that the best fit is obtained when applying a three-model distribution pattern. The modes of the identified three Gaussian distributions, retransformed from the log domain to the mean stimulation temperatures at which the subjects had indicated pain thresholds, were obtained at 23.7 °C, 13.2 °C and 1.5 °C for Gaussian #1, #2 and #3, respectively. The localization of the first and second Gaussians was interpreted as reflecting the contribution of two different cold sensors. From the calculated localization of the modes of the first two Gaussians, the hypothesis of an involvement of TRPM8, sensing temperatures from 25 - 24 °C, and TRPA1, sensing cold from 17 °C can be derived. In that case, subjects belonging to either Gaussian would possess a dominance of the one or the other receptor at the skin area where the cold stimuli had been applied. The findings therefore support a suitability of complex analytical approaches to detect mechanistically determined patterns from pain phenotype data.

  17. Comparison of thermal behavior of natural and hot-washed sisal fibers based on their main components: Cellulose, xylan and lignin. TG-FTIR analysis of volatile products

    International Nuclear Information System (INIS)

    Benítez-Guerrero, Mónica; López-Beceiro, Jorge; Sánchez-Jiménez, Pedro E.; Pascual-Cosp, José


    Highlights: • Thermal decomposition of sisal fibers has been discussed. • Decompositions of lignocellulosic components and sisal are compared by TXRD and TG-FTIR. • Hot washing reduces the temperature range in which sisal decomposition occurs. • Sisal cellulose decomposition goes by an alternative route to levoglucosan generation. - Abstract: This paper presents in a comprehensive way the thermal behavior of natural and hot-washed sisal fibers, based on the fundamental components of lignocellulosic materials: cellulose, xylan and lignin. The research highlights the influence exerted on the thermal stability of sisal fibers by other constituents such as non-cellulosic polysaccharides (NCP) and mineral matter. Thermal changes were investigated by thermal X-ray diffraction (TXRD), analyzing the crystallinity index (%Ic) of cellulosic samples, and by simultaneous thermogravimetric and differential thermal analysis coupled with Fourier-transformed infrared spectrometry (TG/DTA-FTIR), which allowed to examine the evolution of the main volatile compounds evolved during the degradation under inert and oxidizing atmospheres. The work demonstrates the potential of this technique to elucidate different steps during the thermal decomposition of sisal, providing extensible results to other lignocellulosic fibers, through the analysis of the evolution of CO 2 , CO, H 2 O, CH 4 , acetic acid, formic acid, methanol, formaldehyde and 2-butanone, and comparing it with the volatile products from pyrolysis of the biomass components. The hydroxyacetaldehyde detected during pyrolysis of sisal is indicative of an alternative route to that of levoglucosan, generated during cellulose pyrolysis. Hot-washing at 75 °C mostly extracts non-cellulosic components of low decomposition temperature, and reduces the range of temperature in which sisal decomposition occurs, causing a retard in the pyrolysis stage and increasing Tb NCP and Tb CEL , temperatures at the maximum mass loss rate of

  18. Transport, retention, and long-term release behavior of polymer-coated silver nanoparticles in saturated quartz sand: The impact of natural organic matters and electrolyte. (United States)

    Hou, Jun; Zhang, Mingzhi; Wang, Peifang; Wang, Chao; Miao, Lingzhan; Xu, Yi; You, Guoxiang; Lv, Bowen; Yang, Yangyang; Liu, Zhilin


    This study investigated the transport and long-term release of stabilized silver nanoparticles (AgNPs), including polyvinylpyrrolidone-coated AgNPs (PVP-AgNPs) and bare AgNPs (Bare-AgNPs), in the presence of natural organic matters (NOMs; both humic acids (HA) and alginate (Alg)) and an electrolyte (Ca 2+ ) in a sand-packed column. Very low breakthrough rate (C/C 0 ) of AgNPs (below 0.04) occurred in the absence of NOM and the electrolyte. Increasing the concentration of NOM and decreasing the influent NOM solution's ionic strength (IS) reduced the retention of AgNPs. The reduced NP retention at high NOM and low IS was mainly attributed to the increased energy barrier between the AgNPs and the sand grain surface. Notably, the retention of PVP-AgNPs was enhanced at high Alg concentration and low IS, which mainly resulted from the improved hydrophobicity that could increase the interaction between the PVP-AgNPs and the collector. The total release amount of PVP-AgNPs (10.03%, 9.50%, 28.42%, 6.37%) and Bare-AgNPs (3.28%, 2.58%, 10.36%, 1.54%) were gained when exposed to four kinds of NOM solutions, including deionized water, an electrolyte solution (1 mM Ca 2+ ), HA with an electrolyte (1 mM Ca 2+ ), and a Alg (40 mg/L) solution with an electrolyte (1 mM Ca 2+ ). The long-term release of retained silver nanoparticles in the quartz sand was mostly through the form of released Ag NPs. The factors that increased the mobility of AgNPs in quartz sand could improve the release of the AgNPs. The release of AgNPs had no significant change in the presence Ca 2+ but were increased in the presence of HA. The Alg slightly decreased the release of AgNPs by increasing the hydrophobicity of AgNPs. The results of the study indicated that all the tested NOM and Ca 2+ have prominent influence on the transport and long-term release behavior of silver nanoparticles in saturated quartz sand. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. A hybrid approach to increase the informedness of CE-based data using locus-specific thresholding and machine learning. (United States)

    Marciano, Michael A; Williamson, Victoria R; Adelman, Jonathan D


    The interpretation of genetic profiles require a robust and reliable method to discriminate true allelic information from noise, regardless of the instrumentation or methods used. Traditionally, static peak detection thresholds (analytical thresholds) have been applied to capillary electrophoresis generated data to distinguish the true allelic peaks from noise. While the rigid nature of these thresholds attempts to conservatively account for baseline variability across instrument runs, samples, capillaries, dye-channels, injection times, and voltage, its static nature is unable to adapt, leading to a loss of allelic information that exists below the threshold. The method described herein is able to account for this variability by collectively minimizing the incorrect detection of non-allelic artifacts (false positives) and the threshold-induced dropout of true allelic information (false negatives). This is accomplished by using a dynamic locus and sample specific analytical threshold and a machine learning-derived probabilistic artifact detection model. The system produced an allele detection accuracy of 97.2%, an 11.4% increase from the lowest static threshold (50 RFU), with a low incidence of incorrectly identified artifacts (0.79%). This adaptive method outperformed static thresholds in the retention of allelic information content at minimal cost. Copyright © 2018 Elsevier B.V. All rights reserved.

  20. Reinforcement learning for adaptive threshold control of restorative brain-computer interfaces: a Bayesian simulation

    Directory of Open Access Journals (Sweden)

    Robert eBauer


    Full Text Available Restorative brain-computer interfaces (BCI are increasingly used to provide feedback of neuronal states in a bid to normalize pathological brain activity and achieve behavioral gains. However, patients and healthy subjects alike often show a large variability, or even inability, of brain self-regulation for BCI control, known as BCI illiteracy. Although current co-adaptive algorithms are powerful for assistive BCIs, their inherent class switching clashes with the operant conditioning goal of restorative BCIs. Moreover, due to the treatment rationale, the classifier of restorative BCIs usually has a constrained feature space, thus limiting the possibility of classifier adaptation.In this context, we applied a Bayesian model of neurofeedback and reinforcement learning for different threshold selection strategies to study the impact of threshold adaptation of a linear classifier on optimizing restorative BCIs. For each feedback iteration, we first determined the thresholds that result in minimal action entropy and maximal instructional efficiency. We then used the resulting vector for the simulation of continuous threshold adaptation. We could thus show that threshold adaptation can improve reinforcement learning, particularly in cases of BCI illiteracy. Finally, on the basis of information-theory, we provided an explanation for the achieved benefits of adaptive threshold setting.

  1. A Comparison of Thresholds in Auditory Steady - State Response with Pure Tone Audiometry in Subjects with Normal Hearing and Those with Mild and Moderate Sensorineural Hearing los

    Directory of Open Access Journals (Sweden)

    Sadegh Jafarzadeh


    Full Text Available Background and Aim: Among all auditory assessment tools, auditory steady state response (ASSR is a modern test. Modulation frequency for this test is usually 80 Hz. The purpose of this study, was to examined adult subjects with 40 Hz and 80 Hz ASSR and compare the results.Materials and Methods: Thirty adult (60 ears were evaluated by ASSR and PTA test, Results were divided into three groups: normal hearing, mild and moderate sensorineural hearing loss. Results: In all groups, forty hertz ASSR thresholds were relatively closer to behavioral threshold than those of 80 Hz ASSR(p<0.05. Besides, the more severe hearing loss, the lower the difference between those two thresholds. Correlation coefficients were also higher in 40 Hz ASSR(p<0.05. Conclusion: Frequency modulation thresholds with 40 Hz are more likely to be closer to the behavioral thresholds. Moreover, it has better results than the thresholds with 80 Hz.

  2. Evaluation of Threshold: an independent living program for homeless adolescents. (United States)

    Schram, D D; Giovengo, M A


    The Threshold Project, a residential treatment program, was designed to work with homeless and alienated young women who were approaching 18 years of age but lacked the skills, values, and attitudes necessary to care for themselves and assume the responsibilities of adulthood. Project services were designed to prepare these young women for independent living and to break the intergenerational cycle of abuse and neglect experienced by this population. Threshold offered a series of progressively more independent living experiences to young homeless women ages 16-18 years, who had been sexually/physically/emotionally abused or neglected, and who had been involved in or at high risk for prostitution. A majority of the clients responded well to the requirements of the program, including the expectation that they maintain employment and participate in educational programs during the semi-independent living phase of the project. A follow-up assessment undertaken after clients left the project found that 42% of the young women met all "success" criteria, that is, they lived independently (or in stable situations), attended school and/or were employed, had not engaged in prostitution or other offense behavior, and did not abuse alcohol or other substances.

  3. Threshold for improvement in insulin sensitivity with adolescent weight loss. (United States)

    Abrams, Pamela; Levitt Katz, Lorraine E; Moore, Reneé H; Xanthopoulos, Melissa S; Bishop-Gilyard, Chanelle T; Wadden, Thomas A; Berkowitz, Robert I


    To assess the association of weight loss and insulin sensitivity, glucose tolerance, and metabolic syndrome (MS) in obese adolescents following weight loss treatment, and to determine the threshold amount of weight loss required to observe improvements in these measures. A randomized, controlled behavioral weight loss trial was conducted with 113 obese adolescents. Changes in fasting insulin, homeostasis model assessment of insulin resistance, whole body insulin sensitivity index (WBISI), body mass index (BMI), and MS criteria were assessed at baseline and at month 4. There was significant improvement in all measures of insulin sensitivity at month 4. Mean fasting insulin dropped from 22.3 to 16.6 μU/mL (P adolescents. An approximate decrease in BMI of 8% was the threshold level at which insulin sensitivity improved. As more weight loss programs are designed for obese adolescents, it will be important to have reasonable weight loss goals that will yield improvements in metabolic and cardiovascular disease risk factors. Copyright © 2013. Published by Mosby, Inc.

  4. Measuring Input Thresholds on an Existing Board (United States)

    Kuperman, Igor; Gutrich, Daniel G.; Berkun, Andrew C.


    A critical PECL (positive emitter-coupled logic) interface to Xilinx interface needed to be changed on an existing flight board. The new Xilinx input interface used a CMOS (complementary metal-oxide semiconductor) type of input, and the driver could meet its thresholds typically, but not in worst-case, according to the data sheet. The previous interface had been based on comparison with an external reference, but the CMOS input is based on comparison with an internal divider from the power supply. A way to measure what the exact input threshold was for this device for 64 inputs on a flight board was needed. The measurement technique allowed an accurate measurement of the voltage required to switch a Xilinx input from high to low for each of the 64 lines, while only probing two of them. Directly driving an external voltage was considered too risky, and tests done on any other unit could not be used to qualify the flight board. The two lines directly probed gave an absolute voltage threshold calibration, while data collected on the remaining 62 lines without probing gave relative measurements that could be used to identify any outliers. The PECL interface was forced to a long-period square wave by driving a saturated square wave into the ADC (analog to digital converter). The active pull-down circuit was turned off, causing each line to rise rapidly and fall slowly according to the input s weak pull-down circuitry. The fall time shows up as a change in the pulse width of the signal ready by the Xilinx. This change in pulse width is a function of capacitance, pulldown current, and input threshold. Capacitance was known from the different trace lengths, plus a gate input capacitance, which is the same for all inputs. The pull-down current is the same for all inputs including the two that are probed directly. The data was combined, and the Excel solver tool was used to find input thresholds for the 62 lines. This was repeated over different supply voltages and

  5. Analysis of ecological thresholds in a temperate forest undergoing dieback.

    Directory of Open Access Journals (Sweden)

    Philip Martin

    Full Text Available Positive feedbacks in drivers of degradation can cause threshold responses in natural ecosystems. Though threshold responses have received much attention in studies of aquatic ecosystems, they have been neglected in terrestrial systems, such as forests, where the long time-scales required for monitoring have impeded research. In this study we explored the role of positive feedbacks in a temperate forest that has been monitored for 50 years and is undergoing dieback, largely as a result of death of the canopy dominant species (Fagus sylvatica, beech. Statistical analyses showed strong non-linear losses in basal area for some plots, while others showed relatively gradual change. Beech seedling density was positively related to canopy openness, but a similar relationship was not observed for saplings, suggesting a feedback whereby mortality in areas with high canopy openness was elevated. We combined this observation with empirical data on size- and growth-mediated mortality of trees to produce an individual-based model of forest dynamics. We used this model to simulate changes in the structure of the forest over 100 years under scenarios with different juvenile and mature mortality probabilities, as well as a positive feedback between seedling and mature tree mortality. This model produced declines in forest basal area when critical juvenile and mature mortality probabilities were exceeded. Feedbacks in juvenile mortality caused a greater reduction in basal area relative to scenarios with no feedback. Non-linear, concave declines of basal area occurred only when mature tree mortality was 3-5 times higher than rates observed in the field. Our results indicate that the longevity of trees may help to buffer forests against environmental change and that the maintenance of old, large trees may aid the resilience of forest stands. In addition, our work suggests that dieback of forests may be avoidable providing pressures on mature and juvenile trees do

  6. On the Raman threshold of passive large mode area fibers (United States)

    Jauregui, Cesar; Limpert, Jens; Tünnermann, Andreas


    The output power of fiber optic laser systems has been exponentially increasing in the last years. However, non-linear effects, and in particular stimulated Raman scattering (SRS), are threatening to seriously limit the development pace in the near future. SRS can take place anywhere along the laser system, however it is actually the passive delivery fiber at the end of the system, the section where SRS is most likely to occur. The common way to combat this problem is to use the so-called Large Mode Area (LMA) fibers. However, these fibers are expensive and have a multimode nature that will either reduce the beam quality of the laser output or require a careful excitation of the fundamental mode. Furthermore, the larger the core area, the more complicated it will be to sustain single-mode operation. Therefore, it is becoming increasingly important to be able to determine which is the minimum core area required in the delivery fiber to avoid SRS. This calculation is usually carried out using the conventional formula for the Raman Threshold published by R.G. Smith in 1972: Pth =16Aeff gRLeff . In this work we demonstrate that this formula and the conclusions derived from it are inaccurate for short (several meters long) LMA fibers. For example, one widely spread belief (obtained from this expression) is that there is no dependence of the Raman intensity threshold (Ith=Pth/Aeff) on the mode area. However, our calculations show otherwise. Additionally, we have obtained an improved Raman threshold formula valid for short LMA fibers.

  7. Possible evidence for a narrow isovector B=2 resonance below pion production threshold

    International Nuclear Information System (INIS)

    Tatischeff, B.; Comets, M.P.; Le Bornec, Y.; Willis, N.; Fassnacht, P.; Hibou, F.


    Some evidence is presented for a narrow peak at 1969±2 MeV (FWHM=9±2 MeV) in the missing mass spectrum of the 3 He(p,d) reaction, with 3 standard deviations. The nature of this state, the mass of which is below the NN threshold, is discussed in connection with structures found in other experiments. (orig.)

  8. Preliminary test of cigarette nicotine discrimination threshold in non-dependent versus dependent smokers. (United States)

    Perkins, Kenneth A; Kunkle, Nicole; Karelitz, Joshua L; Perkins, K A; Kunkle, N; Karelitz, J L


    Despite its potential for understanding tobacco dependence, behavioral discrimination of nicotine via smoking has not been formally examined as a function of nicotine dependence level. Spectrum research cigarettes were used to compare non-dependent with dependent smokers on the lowest content of nicotine they could discriminate (i.e., "threshold"). Dependent (n=21; 16M, 5F) or non-dependent (n=7; 4M, 3F) smokers were tested on ability to discriminate between cigarettes with nicotine contents of 17, 11, 5, 2, and 1mg/g, one per session, from an "ultra-low" cigarette with 0.4mg/g (all had 9-10mg "tar"). All abstained from smoking overnight prior to sessions, and number of sessions was determined by the lowest nicotine content they could reliably discriminate from the ultra-low on >80% of trials (i.e., ≥5 of 6). Subjective perceptions and cigarette choice behavior were also assessed and related to discrimination behavior. Discrimination thresholds (and most perceptions) did not differ between dependent and non-dependent smokers, with median thresholds of 11mg/g for both subgroups. Yet, "liking" and puff choice for threshold cigarettes were greater in dependent but not non-dependent smokers, while cigarettes with nicotine contents below threshold did not support "liking" or choice in both groups. In sum, this preliminary study suggests threshold for discriminating nicotine via smoking may not vary by dependence level, and further study is needed to confirm that cigarettes unable to be discriminated are also not reinforcing. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Threshold pion electroproduction at large momentum transfers; Threshold Pion-Elektroproduktion bei grossen Energieuebertraegen

    Energy Technology Data Exchange (ETDEWEB)

    Peters, Andreas


    We consider pion electroproduction close to threshold for Q{sup 2} in the region 1-10 GeV{sup 2} on a nucleon target. The momentum transfer dependence of the S-wave multipoles at threshold, E{sub 0+} and L{sub 0+}, is calculated in the chiral limit using light-cone sum rules. Predictions for the cross sections in the threshold region are given taking into account P-wave contributions that, as we argue, are model independent to a large extent. The results are compared with the SLAC E136 data on the structure function F{sub 2}(W,Q{sup 2}) in the threshold region. (orig.)

  10. Influence of the nature of the transition element M of the magnetic behavior of uranium in new ternary silicides and germanide UsMtXv (M = Fe, Co, Ni, Ru, Rh, Pd, Os, Ir, Pt and X = Si, Ge)

    International Nuclear Information System (INIS)

    Hickey, Eugene


    Structural, magnetic and electrical properties of three new series of ternary compounds based on uranium (U 2 M 3 X 5 , U 2 MSi 3 and UMEG2) were determined. The magnetic state of uranium in these compounds depends on the nature of the transition element M. This behavior is explained by significant competition between Kondo-type interactions and magnetic interactions type RKKY This accounts for the non-magnetic magnetic transition undergone by uranium in some systems. (author)

  11. Occupation and its relationship with health and wellbeing: the threshold concept for occupational therapy. (United States)

    Fortune, Tracy; Kennedy-Jones, Mary


    We introduce the educational framework of 'threshold concepts' and discuss its utility in understanding the fundamental difficulties learners have in understanding ways of thinking and practising as occupational therapists. We propose that the relationship between occupation and health is a threshold concept for occupational therapy because of students' trouble in achieving lasting conceptual change in relation to their understanding of it. The authors present and discuss key ideas drawn from educational writings on threshold concepts, review the emerging literature on threshold concepts in occupational therapy, and pose a series of questions in order to prompt consideration of the pedagogical issues requiring action by academic and fieldwork educators. Threshold concepts in occupational therapy have been considered in a primarily cross-disciplinary sense, that is, the understandings that occupational therapy learners grapple with are relevant to learners in other disciplines. In contrast, we present a more narrowly defined conception that emphasises the 'bounded-ness' of the concept to the discipline. A threshold concept that captures the essential nature of occupational therapy is likely to be (highly) troublesome in terms of a learner's acquisition of it. Rather than simplifying these learning 'jewels' educators are encouraged to sit with the discomfort that they and the learner may experience as the learner struggles to grasp them. Moreover, they should reshape their curricula to provoke such struggles if transformative learning is to be the outcome. © 2014 Occupational Therapy Australia.

  12. Physico-chemical thresholds in the distribution of fish species among French lakes

    Directory of Open Access Journals (Sweden)

    Roubeix Vincent


    Full Text Available The management of lakes requires the definition of physico-chemical thresholds to be used for ecosystem preservation or restoration. According to the European Water Framework Directive, the limits between physico-chemical quality classes must be set consistently with biological quality elements. One way to do this consists in analyzing the response of aquatic communities to environmental gradients across monitoring sites and in identifying ecological community thresholds, i.e. zones in the gradients where the species turnover is the highest. In this study, fish data from 196 lakes in France were considered to derive ecological thresholds using the multivariate method of gradient forest. The analysis was performed on 25 species and 36 environmental parameters. The results revealed the highest importance of maximal water temperature in the distribution of fish species. Other important parameters included geographical factors, dissolved organic carbon concentration and water transparency, while nutrients appeared to have low influence. In spite of the diversity of species responses to the gradients, community thresholds were detected in the gradients of the most important physico-chemical parameters and of total phosphorus and nitrate concentrations as well. The thresholds identified in such macroecological study may highlight new patterns of species natural distribution and improve niche characterization. Moreover, when factors that may be influenced by human activities are involved, the thresholds could be used to set environmental standards for lake preservation.

  13. Predicting visual acuity from detection thresholds. (United States)

    Newacheck, J S; Haegerstrom-Portnoy, G; Adams, A J


    Visual performance based exclusively on high luminance and high contrast letter acuity measures often fails to predict individual performance at low contrast and low luminance. Here we measured visual acuity over a wide range of contrasts and luminances (low mesopic to photopic) for 17 young normal observers. Acuity vs. contrast functions appear to fit a single template which can be displaced laterally along the log contrast axis. The magnitude of this lateral displacement for different luminances was well predicted by the contrast threshold difference for a 4 min arc spot. The acuity vs. contrast template, taken from the mean of all 17 subjects, was used in conjunction with individual spot contrast threshold measures to predict an individual's visual acuity over a wide range of luminance and contrast levels. The accuracy of the visual acuity predictions from this simple procedure closely approximates test-retest accuracy for both positive (projected Landolt rings) and negative contrast (Bailey-Lovie charts).

  14. Edith Wharton's threshold phobia and two worlds. (United States)

    Holtzman, Deanna; Kulish, Nancy


    The American novelist Edith Wharton suffered an unusual childhood neurotic symptom, a fear of crossing thresholds, a condition that might be called a "threshold phobia." This symptom is identified and examined in autobiographical material, letters, diaries, and selected literary fiction and nonfiction left by Wharton to arrive at a formulation not previously drawn together. A fascinating theme-living or being trapped between "two worlds"-runs through much of the writer's life and work. The phobia is related to this theme, and both can be linked more broadly to certain sexual conflicts in women. This understanding of Wharton's phobia, it is argued, throws new light on the developmental issues and conflicts related to the female "oedipal" or triadic phase, characterized by the need to negotiate the two worlds of mother and of father. © 2014 by the American Psychoanalytic Association.

  15. Multiparty Computation from Threshold Homomorphic Encryption

    DEFF Research Database (Denmark)

    Cramer, Ronald; Damgård, Ivan Bjerre; Nielsen, Jesper Buus


    We introduce a new approach to multiparty computation (MPC) basing it on homomorphic threshold crypto-systems. We show that given keys for any sufficiently efficient system of this type, general MPC protocols for n parties can be devised which are secure against an active adversary that corrupts...... any minority of the parties. The total number of bits broadcast is O(nk|C|), where k is the security parameter and |C| is the size of a (Boolean) circuit computing the function to be securely evaluated. An earlier proposal by Franklin and Haber with the same complexity was only secure for passive...... adversaries, while all earlier protocols with active security had complexity at least quadratic in n. We give two examples of threshold cryptosystems that can support our construction and lead to the claimed complexities....

  16. The Resting Motor Threshold - Restless or Resting?

    DEFF Research Database (Denmark)

    Karabanov, Anke Ninija; Raffin, Estelle Emeline; Siebner, Hartwig Roman


    Background The resting motor threshold (RMT) is used to individually adjust the intensity of transcranial magnetic stimulation (TMS) intensity and is assumed to be stable. Here we challenge this notion by showing that RMT expresses acute context-dependent fluctuations. Method In twelve participants......, the RMT of the right first dorsal interosseus muscle was repeatedly determined using a threshold-hunting procedure while participants performed motor imagery and visual attention tasks with the right or left hand. Data were analyzed using repeated-measure ANOVA. Results RMT differed depending on which...... hand performed the task (P = 0.003). RMT of right FDI was lower during motor imagery than during visual attention of the right hand (P = 0.002), but did not differ between left-hand tasks (P = 0.988). Conclusions State-dependent changes of RMT occur in absence of overt motor activity and can...

  17. Gamin partable radiation meter with alarm threshold

    International Nuclear Information System (INIS)

    Payat, Rene.


    The Gamin Radiation meter is a direct reading, portable, battery-powered gamma doserate meter featuring alarm thresholds. Doserate is read on a micro-ammeter with a millirad-per-hour logarithmic scale, covering a range of 0,1 to 1000 millirads/hour. The instrument issues an audible warning signal when dose-rate level exceeds a threshold value, which can be selected. The detector tube is of the Geiger-Muller counter, energy compensated type. Because of its low battery drain, the instrument can be operated continously for 1000 hours. It is powered by four 1.5 volt alcaline batteries of the R6 type. The electronic circuitry is housed in a small lightweight case made of impact resistant plastic. Applications of the Gamin portable radiation monitor are found in health physics, safety departments, medical facilities, teaching, civil defense [fr

  18. Rayleigh scattering from ions near threshold

    International Nuclear Information System (INIS)

    Roy, S.C.; Gupta, S.K.S.; Kissel, L.; Pratt, R.H.


    Theoretical studies of Rayleigh scattering of photons from neon atoms with different degrees of ionization, for energies both below and above the K-edges of the ions, are presented. Some unexpected structures both in Rayleigh scattering and in photoionization from neutral and weakly ionized atoms, very close to threshold, have been reported. It has recently been realized that some of the predicted structures may have a nonphysical origin and are due to the limitation of the independent-particle model and also to the use of a Coulombic Latter tail. Use of a K-shell vacancy potential - in which an electron is assumed to be removed from the K-shell - in calculating K-shell Rayleigh scattering amplitudes removes some of the structure effects near threshold. We present in this work a discussion of scattering angular distributions and total cross sections, obtained utilizing vacancy potentials, and compare these predictions with those previously obtained in other potential model. (author) [pt

  19. The monolithic double-threshold discriminator

    International Nuclear Information System (INIS)

    Baturitsky, M.A.; Dvornikov, O.V.


    A double-threshold discriminator capable of processing input signals of different duration is described. Simplicity of the discriminator circuitry makes it possible to embody the discriminator in multichannel ICs using microwave bipolar-JFET technology. Time walk is calculated to be less than 0.35 ns for the input ramp signals with rise times 25-100 ns and amplitudes 50 mV-1 V

  20. Bivariate hard thresholding in wavelet function estimation


    Piotr Fryzlewicz


    We propose a generic bivariate hard thresholding estimator of the discrete wavelet coefficients of a function contaminated with i.i.d. Gaussian noise. We demonstrate its good risk properties in a motivating example, and derive upper bounds for its mean-square error. Motivated by the clustering of large wavelet coefficients in real-life signals, we propose two wavelet denoising algorithms, both of which use specific instances of our bivariate estimator. The BABTE algorithm uses basis averaging...

  1. Estimasi Regresi Wavelet Thresholding Dengan Metode Bootstrap


    Suparti, Suparti; Mustofa, Achmad; Rusgiyono, Agus


    Wavelet is a function that has the certainly characteristic for example, it oscillate about zero point ascillating, localized in the time and frequency domain and construct the orthogonal bases in L2(R) space. On of the wavelet application is to estimate non parametric regression function. There are two kinds of wavelet estimator, i.e., linear and non linear wavelet estimator. The non linear wavelet estimator is called a thresholding wavelet rstimator. The application of the bootstrap method...

  2. Near threshold studies of photoelectron satellites

    International Nuclear Information System (INIS)

    Heimann, P.A.


    Photoelectron spectroscopy and synchrotron radiation have been used to study correlation effects in the rare gases: He, Ne, Ar, Kr, and Xe. Two kinds of time-of-flight electron analyzers were employed to examine photoionization very close to threshold and at higher kinetic energies. Partial cross sections and angular distributions have been measured for a number of photoelectron satellites. The shake-off probability has been determined at some inner-shell resonances. 121 refs., 28 figs., 13 tabs

  3. Threshold Learning Dynamics in Social Networks (United States)

    González-Avella, Juan Carlos; Eguíluz, Victor M.; Marsili, Matteo; Vega-Redondo, Fernado; San Miguel, Maxi


    Social learning is defined as the ability of a population to aggregate information, a process which must crucially depend on the mechanisms of social interaction. Consumers choosing which product to buy, or voters deciding which option to take with respect to an important issue, typically confront external signals to the information gathered from their contacts. Economic models typically predict that correct social learning occurs in large populations unless some individuals display unbounded influence. We challenge this conclusion by showing that an intuitive threshold process of individual adjustment does not always lead to such social learning. We find, specifically, that three generic regimes exist separated by sharp discontinuous transitions. And only in one of them, where the threshold is within a suitable intermediate range, the population learns the correct information. In the other two, where the threshold is either too high or too low, the system either freezes or enters into persistent flux, respectively. These regimes are generally observed in different social networks (both complex or regular), but limited interaction is found to promote correct learning by enlarging the parameter region where it occurs. PMID:21637714

  4. Near threshold computing technology, methods and applications

    CERN Document Server

    Silvano, Cristina


    This book explores near-threshold computing (NTC), a design-space using techniques to run digital chips (processors) near the lowest possible voltage.  Readers will be enabled with specific techniques to design chips that are extremely robust; tolerating variability and resilient against errors.  Variability-aware voltage and frequency allocation schemes will be presented that will provide performance guarantees, when moving toward near-threshold manycore chips.  ·         Provides an introduction to near-threshold computing, enabling reader with a variety of tools to face the challenges of the power/utilization wall; ·         Demonstrates how to design efficient voltage regulation, so that each region of the chip can operate at the most efficient voltage and frequency point; ·         Investigates how performance guarantees can be ensured when moving towards NTC manycores through variability-aware voltage and frequency allocation schemes.  .

  5. Threshold photoelectron spectroscopy of acetaldehyde and acrolein

    International Nuclear Information System (INIS)

    Yencha, Andrew J.; Siggel-King, Michele R.F.; King, George C.; Malins, Andrew E.R.; Eypper, Marie


    Highlights: •High-resolution threshold photoelectron spectrum of acetaldehyde. •High-resolution threshold photoelectron spectrum of acrolein. •High-resolution total photoion yield spectrum of acetaldehyde. •High-resolution total photoion yield spectrum of acrolein. •Determination of vertical ionization potentials in acetaldehyde and acrolein. -- Abstract: High-resolution (6 meV and 12 meV) threshold photoelectron (TPE) spectra of acetaldehyde and acrolein (2-propenal) have been recorded over the valence binding energy region 10–20 eV, employing synchrotron radiation and a penetrating-field electron spectrometer. These TPE spectra are presented here for the first time. All of the band structures observed in the TPE spectra replicate those found in their conventional HeI photoelectron (PE) spectra. However, the relative band intensities are found to be dramatically different in the two types of spectra that are attributed to the different dominant operative formation mechanisms. In addition, some band shapes and their vertical ionization potentials are found to differ in the two types of spectra that are associated with the autoionization of Rydberg states in the two molecules

  6. Treatment of threshold retinopathy of prematurity

    Directory of Open Access Journals (Sweden)

    Deshpande Dhanashree


    Full Text Available This report deals with our experience in the management of threshold retinopathy of prematurity (ROP. A total of 45 eyes of 23 infants were subjected to treatment of threshold ROP. 26.1% of these infants had a birth weight of >l,500 gm. The preferred modality of treatment was laser indirect photocoagulation, which was facilitated by scleral depression. Cryopexy was done in cases with nondilating pupils or medial haze and was always under general anaesthesia. Retreatment with either modality was needed in 42.2% eyes; in this the skip areas were covered. Total regression of diseases was achieved in 91.1% eyes with no sequelae. All the 4 eyes that progressed to stage 5 despite treatment had zone 1 disease. Major treatment-induced complications did not occur in this series. This study underscores the importance of routine screening of infants upto 2,000 gm birth weight for ROP and the excellent response that is achieved with laser photocoagulation in inducing regression of threshold ROP. Laser is the preferred method of treatment in view of the absence of treatment-related morbidity to the premature infants.

  7. Auditory temporal resolution threshold in elderly individuals. (United States)

    Queiroz, Daniela Soares de; Momensohn-Santos, Teresa Maria; Branco-Barreiro, Fátima Cristina Alves


    the Random Gap Detection Test (RGDT) evaluates temporal resolution threshold. There are doubts as to whether performance in this task remains unchanged with the aging process. At the same time, there is a concern about how much the difficulties of communication experienced by elderly individuals are related to the deterioration of temporal resolution. to determine auditory temporal resolution threshold in elderly individuals with normal peripheral hearing or symmetric mild sensorineural hearing loss, and to correlate findings with gender, age, audiometric findings and scores obtained in the Self - Assessment of Communication (SAC) questionnaire. 63 elderly individuals, aged between 60 and 80 years (53 women and 10 men), were submitted to the RGDT and the SAC. statistical analysis of the relationship between gender and the RGDT indicated that the performance of elderly females was statistically poorer when compared to elderly males. Age and audiometric configuration did not correlate to performance in the RDGT and in the SAC. The results indicate that in the SAC both genders presented no significant complaints about communication difficulties regardless of the outcome obtained in the RGDT or audiometric configuration. the average temporal resolution threshold for women was 104.81ms. Considering gender, females did not present correlations between age and audiometric configuration, not only when considering the RGDT results but also when analyzing the SAC results.

  8. Chemical sensing thresholds for mine detection dogs (United States)

    Phelan, James M.; Barnett, James L.


    Mine detection dogs have been found to be an effective method to locate buried landmines. The capabilities of the canine olfaction method are from a complex combination of training and inherent capacity of the dog for odor detection. The purpose of this effort was to explore the detection thresholds of a limited group of dogs that were trained specifically for landmine detection. Soils were contaminated with TNT and 2,4-DNT to develop chemical vapor standards to present to the dogs. Soils contained ultra trace levels of TNT and DNT, which produce extremely low vapor levels. Three groups of dogs were presented the headspace vapors from the contaminated soils in work environments for each dog group. One positive sample was placed among several that contained clean soils and, the location and vapor source (strength, type) was frequently changed. The detection thresholds for the dogs were determined from measured and extrapolated dilution of soil chemical residues and, estimated soil vapor values using phase partitioning relationships. The results showed significant variances in dog sensing thresholds, where some dogs could sense the lowest levels and others had trouble with even the highest source. The remarkable ultra-trace levels detectable by the dogs are consistent with the ultra-trace chemical residues derived from buried landmines; however, poor performance may go unnoticed without periodic challenge tests at levels consistent with performance requirements.

  9. Treating acetaminophen overdose: thresholds, costs and uncertainties. (United States)

    Gosselin, S; Hoffman, R S; Juurlink, D N; Whyte, I; Yarema, M; Caro, J


    The United Kingdom's Medicines and Healthcare Products Regulatory Agency (MHRA) modified the indications for N-acetylcysteine therapy of acetaminophen (paracetamol) overdose in September 2012. The new treatment threshold line was lowered to 100 mg/L (662 μmol/L) for a 4 hours acetaminophen concentration from the previous 200 mg/L (1325 μmol/L). This decision has the potential to substantially increase overall costs associated with acetaminophen overdose with unclear benefits from a marginal increase in patients protected from hepatotoxicity, fulminant hepatic failure, death, or transplant. Changing the treatment threshold for acetaminophen overdose also implies that ingestion amounts previously thought not to require acetaminophen concentration measurements would need to be revised. As a result, more individuals will be sent to hospitals in order that everyone with a predicted 4 hours concentration above the 100 mg/L line will have concentrations measured and potentially be treated with N-acetylcysteine. Before others consider adopting this new treatment guideline, formal cost-effectiveness analyses need to be performed to define the appropriate thresholds for referral and treatment.

  10. Surface Runoff Threshold Responses to Rainfall Intensity, Scale, and Land Use Type, Change and Disturbance (United States)

    Bhaskar, A.; Kampf, S. K.; Green, T. R.; Wilson, C.; Wagenbrenner, J.; Erksine, R. H.


    The dominance of infiltration-excess (Hortonian) overland flow can be determined by how well a rainfall intensity threshold predicts streamflow response. Areas in which we would expect infiltration-excess overland flow to dominate include urban, bedrock, desert pavement, and lands disturbed by vegetation removal (e.g., after a fire burn or fallow agricultural lands). Using a transferable method of identifying the existence of thresholds, we compare the following sites to investigate their hydrologic responses to 60-minute rainfall intensities: desert pavement sites in Arizona (Walnut Gulch and Yuma Proving Ground), post-fire sites in a forested, mountainous burn area in north-central Colorado (High Park Fire), an area of northeastern Colorado Plains that has transitioned from dryland agriculture to conservation reserve (Drake Farm), and watersheds in suburban Baltimore, Maryland which range from less than 5% to over 50% impervious surface cover. We observed that at desert sites, the necessary threshold of rainfall intensity to produce flow increased with watershed size. In burned watersheds, watershed size did not have a clear effect on rainfall thresholds, but thresholds increased with time after burning, with streamflow no longer exhibiting clear threshold responses after the third year post-fire. At the agricultural site, the frequency of runoff events decreased during the transition from cultivated crops to mixed perennial native grasses. In an area where the natural land cover (forested) would be not dominated by infiltration-excess overland flow, urbanization greatly lowered the rainfall thresholds needed for hydrologic response. This work contributes to building a predictive framework for identifying what naturally-occurring landscapes are dominated by infiltration-excess overland flow, and how land use change could shift the dominance of infiltration-excess overland flow. Characterizing the driving mechanism for streamflow generation will allow better

  11. Absence of the threshold anomaly in the elastic scattering of the weakly bound projectile 7Li on 27Al

    International Nuclear Information System (INIS)

    Figueira, J.M.; Abriola, D.; Niello, J.O. Fernandez; Arazi, A.; Capurro, O.A.; Barbara, E. de; Marti, G.V.; Martinez Heimann, D.; Pacheco, A.J.; Testoni, J.E.; Padron, I.; Gomes, P.R.S.; Lubian, J.


    To study the conditions leading to the appearance of the threshold anomaly in systems involving weakly bound projectiles we measured elastic scattering cross sections for the 7 Li+ 27 Al system at ten different bombarding energies. The results were exhaustively analyzed using different optical model potentials. The similar behavior observed in all these analyses allows us to conclude that no threshold anomaly is found for the present system

  12. Characteristics of oil sludge from crude oil terminal and behaviors of the naturally occurring radioactive materials and heavy metals on combustion of the sludge

    International Nuclear Information System (INIS)

    Mohamad Puad Abu


    The study on the characteristics and behaviors of Naturally Occurring Radioactive Materials (NORM) and heavy metals (HM) in the oil sludge from the crude oil terminal were performed using Gamma Spectroscopy (GM), Neutron Activation Analysis Instrumental (NAAI) and Inductively Coupled Plasma Mass Spectroscopy (ICP-MS). GM and NAAI were used to analyze the concentrations of radionuclides whereas NAAI as well as ICP-MS techniques were applied for HM. The samples were then combusted at temperature ranging from 100 degree Celsius - 800 degree Celsius for a period of 30-150 minutes. The ashes produced were then analyzed again for the various elemental concentrations by the above techniques. The percentage of volatilization was then derived mathematically. The concentration of Ra-226 (123 Bq/ kg) and Ra-228 (117 Bq/ kg) in the oil sludge are higher compared with their parent U-238 (32.12 Bq/ kg) and Th-232 (35.36 Bq/ kg). The concentration of HM such as As (13.30 ppm), Cr (46 ppm) and Zn (4287 ppm) in the oil sludge are also higher compared with As (7.5 ppm), Cr (43 ppm) and Zn (36 ppm) contain in the Malaysian normal soil. The heating value for crude oil sludge is 9000 kJ/ kg which is below the value for self-sustaining combustion (11000 kJ/ kg). The percentage of volatilization varies from 2-70 % depends on the elements, temperature and period of combustion. Uranium was found to volatile more than other elements. Higher temperatures (>500 degree Celsius) and longer exposure time (>90 minutes) promoted metal and radionuclide volatilization significantly more than 20 %. Based on the first order kinetic reaction, a new global mathematical model was developed (Q e =1-e -k e t ). This model can predict the percentage of volatilization for the various elements contain in the sludge if the temperature and time of combustion are known. With this known percentage of volatilization, the concentration of various elements present in the bottom and fly ashes can be deduced. From

  13. Threshold-dependent sample sizes for selenium assessment with stream fish tissue (United States)

    Hitt, Nathaniel P.; Smith, David R.


    Natural resource managers are developing assessments of selenium (Se) contamination in freshwater ecosystems based on fish tissue concentrations. We evaluated the effects of sample size (i.e., number of fish per site) on the probability of correctly detecting mean whole-body Se values above a range of potential management thresholds. We modeled Se concentrations as gamma distributions with shape and scale parameters fitting an empirical mean-to-variance relationship in data from southwestern West Virginia, USA (63 collections, 382 individuals). We used parametric bootstrapping techniques to calculate statistical power as the probability of detecting true mean concentrations up to 3 mg Se/kg above management thresholds ranging from 4 to 8 mg Se/kg. Sample sizes required to achieve 80% power varied as a function of management thresholds and Type I error tolerance (α). Higher thresholds required more samples than lower thresholds because populations were more heterogeneous at higher mean Se levels. For instance, to assess a management threshold of 4 mg Se/kg, a sample of eight fish could detect an increase of approximately 1 mg Se/kg with 80% power (given α = 0.05), but this sample size would be unable to detect such an increase from a management threshold of 8 mg Se/kg with more than a coin-flip probability. Increasing α decreased sample size requirements to detect above-threshold mean Se concentrations with 80% power. For instance, at an α-level of 0.05, an 8-fish sample could detect an increase of approximately 2 units above a threshold of 8 mg Se/kg with 80% power, but when α was relaxed to 0.2, this sample size was more sensitive to increasing mean Se concentrations, allowing detection of an increase of approximately 1.2 units with equivalent power. Combining individuals into 2- and 4-fish composite samples for laboratory analysis did not decrease power because the reduced number of laboratory samples was compensated for by increased

  14. Determining lower threshold concentrations for synergistic effects. (United States)

    Bjergager, Maj-Britt Andersen; Dalhoff, Kristoffer; Kretschmann, Andreas; Nørgaard, Katrine Banke; Mayer, Philipp; Cedergreen, Nina


    Though only occurring rarely, synergistic interactions between chemicals in mixtures have long been a point of focus. Most studies analyzing synergistic interactions used unrealistically high chemical concentrations. The aim of the present study is to determine the threshold concentration below which proven synergists cease to act as synergists towards the aquatic crustacean Daphnia magna. To do this, we compared several approaches and test-setups to evaluate which approach gives the most conservative estimate for the lower threshold for synergy for three known azole synergists. We focus on synergistic interactions between the pyrethroid insecticide, alpha-cypermethrin, and one of the three azole fungicides prochloraz, propiconazole or epoxiconazole measured on Daphnia magna immobilization. Three different experimental setups were applied: A standard 48h acute toxicity test, an adapted 48h test using passive dosing for constant chemical exposure concentrations, and a 14-day test. Synergy was defined as occuring in mixtures where either EC 50 values decreased more than two-fold below what was predicted by concentration addition (horizontal assessment) or as mixtures where the fraction of immobile organisms increased more than two-fold above what was predicted by independent action (vertical assessment). All three tests confirmed the hypothesis of the existence of a lower azole threshold concentration below which no synergistic interaction was observed. The lower threshold concentration, however, decreased with increasing test duration from 0.026±0.013μM (9.794±4.897μgL -1 ), 0.425±0.089μM (145.435±30.46μgL -1 ) and 0.757±0.253μM (249.659±83.44μgL -1 ) for prochloraz, propiconazole and epoxiconazole in standard 48h toxicity tests to 0.015±0.004μM (5.651±1.507μgL -1 ), 0.145±0.025μM (49.619±8.555μgL -1 ) and 0.122±0.0417μM (40.236±13.75μgL -1 ), respectively, in the 14-days tests. Testing synergy in relation to concentration addition provided

  15. A Robust Threshold for Iterative Channel Estimation in OFDM Systems

    Directory of Open Access Journals (Sweden)

    A. Kalaycioglu


    Full Text Available A novel threshold computation method for pilot symbol assisted iterative channel estimation in OFDM systems is considered. As the bits are transmitted in packets, the proposed technique is based on calculating a particular threshold for each data packet in order to select the reliable decoder output symbols to improve the channel estimation performance. Iteratively, additional pilot symbols are established according to the threshold and the channel is re-estimated with the new pilots inserted to the known channel estimation pilot set. The proposed threshold calculation method for selecting additional pilots performs better than non-iterative channel estimation, no threshold and fixed threshold techniques in poor HF channel simulations.

  16. Quasi-one-dimensional intermittent flux behavior in superconducting films

    DEFF Research Database (Denmark)

    Qviller, A. J.; Yurchenko, V. V.; Galperin, Y. M.


    Intermittent filamentary dynamics of the vortex matter in superconductors is found in films of YBa2Cu3O7-δ deposited on tilted substrates. Deposition of this material on such substrates creates parallel channels of easy flux penetration when a magnetic field is applied perpendicular to the film....... The intermittent behavior shows no threshold value in the applied field, in contrast to conventional flux jumping. The results strongly suggest that the quasi-one-dimensional flux jumps are of a different nature than the thermomagnetic dendritic (branching) avalanches that are commonly found in superconducting...

  17. Stylized facts from a threshold-based heterogeneous agent model (United States)

    Cross, R.; Grinfeld, M.; Lamba, H.; Seaman, T.


    A class of heterogeneous agent models is investigated where investors switch trading position whenever their motivation to do so exceeds some critical threshold. These motivations can be psychological in nature or reflect behaviour suggested by the efficient market hypothesis (EMH). By introducing different propensities into a baseline model that displays EMH behaviour, one can attempt to isolate their effects upon the market dynamics. The simulation results indicate that the introduction of a herding propensity results in excess kurtosis and power-law decay consistent with those observed in actual return distributions, but not in significant long-term volatility correlations. Possible alternatives for introducing such long-term volatility correlations are then identified and discussed.

  18. Animal Sociology and a Natural Economy of the Body Politic, Part II: The Past Is the Contested Zone: Human Nature and Theories of Production and Reproduction in Primate Behavior Studies. (United States)

    Haraway, Donna


    Theories of animal and human society based on sex and reproduction have been powerful in legitimating beliefs in the natural necessity of aggression, competition, and hierarchy. Feminists attempting to answer this bias are caught in a political-scientific struggle to formulate and articulate adequate biosocial theories. (Author/KR)

  19. A comparison of the survival and migratory behavior of hatchery-reared and naturally reared steelhead smolts in the Alsea river and estuary, Oregon, using acoustic telemetry (United States)

    We tracked three groups of steelhead Oncorhynchus mykiss smolts implanted with acoustic transmitters to determine whether the degree of hatchery domestication or the juvenile rearing environment (hatchery raceway versus natural stream) influenced migration timing and survival in ...

  20. Self-organized sorting limits behavioral variability in swarms. (United States)

    Copenhagen, Katherine; Quint, David A; Gopinathan, Ajay


    Swarming is a phenomenon where collective motion arises from simple local interactions between typically identical individuals. Here, we investigate the effects of variability in behavior among the agents in finite swarms with both alignment and cohesive interactions. We show that swarming is abolished above a critical fraction of non-aligners who do not participate in alignment. In certain regimes, however, swarms above the critical threshold can dynamically reorganize and sort out excess non-aligners to maintain the average fraction close to the critical value. This persists even in swarms with a distribution of alignment interactions, suggesting a simple, robust and efficient mechanism that allows heterogeneously mixed populations to naturally regulate their composition and remain in a collective swarming state or even differentiate among behavioral phenotypes. We show that, for evolving swarms, this self-organized sorting behavior can couple to the evolutionary dynamics leading to new evolutionarily stable equilibrium populations set by the physical swarm parameters.

  1. Hydrometeorological threshold conditions for debris flow initiation in Norway

    Directory of Open Access Journals (Sweden)

    N. K. Meyer


    Full Text Available Debris flows, triggered by extreme precipitation events and rapid snow melt, cause considerable damage to the Norwegian infrastructure every year. To define intensity-duration (ID thresholds for debris flow initiation critical water supply conditions arising from intensive rainfall or snow melt were assessed on the basis of daily hydro-meteorological information for 502 documented debris flow events. Two threshold types were computed: one based on absolute ID relationships and one using ID relationships normalized by the local precipitation day normal (PDN. For each threshold type, minimum, medium and maximum threshold values were defined by fitting power law curves along the 10th, 50th and 90th percentiles of the data population. Depending on the duration of the event, the absolute threshold intensities needed for debris flow initiation vary between 15 and 107 mm day−1. Since the PDN changes locally, the normalized thresholds show spatial variations. Depending on location, duration and threshold level, the normalized threshold intensities vary between 6 and 250 mm day−1. The thresholds obtained were used for a frequency analysis of over-threshold events giving an estimation of the exceedance probability and thus potential for debris flow events in different parts of Norway. The absolute thresholds are most often exceeded along the west coast, while the normalized thresholds are most frequently exceeded on the west-facing slopes of the Norwegian mountain ranges. The minimum thresholds derived in this study are in the range of other thresholds obtained for regions with a climate comparable to Norway. Statistics reveal that the normalized threshold is more reliable than the absolute threshold as the former shows no spatial clustering of debris flows related to water supply events captured by the threshold.

  2. A low-threshold high-index-contrast grating (HCG)-based organic VCSEL (United States)

    Shayesteh, Mohammad Reza; Darvish, Ghafar; Ahmadi, Vahid


    We propose a low-threshold high-index-contrast grating (HCG)-based organic vertical-cavity surface-emitting laser (OVCSEL). The device has the feasibility to apply both electrical and optical excitation. The microcavity of the laser is a hybrid photonic crystal (HPC) in which the top distributed Bragg reflector (DBR) is replaced by a sub-wavelength high-contrast-grating layer, and provides a high-quality factor. The simulated quality factor of the microcavity is shown to be as high as 282,000. We also investigate the threshold behavior and the dynamics of the OVCSEL optically pumped with sub-picosecond pulses. Results from numerical simulation show that lasing threshold is 75 nJ/cm2.

  3. Dependence of mechanical performances of polymer/carbon nanotubes nanocomposites on percolation threshold (United States)

    Nikfar, Nafiseh; Zare, Yasser; Rhee, Kyong Yop


    In this study, several models for the tensile modulus and strength of polymer/carbon nanotubes (CNT) nanocomposites (PCNT) are expressed as a function of percolation threshold. The roles of the CNT aspect ratio α and percolation threshold φp in the mechanical properties of PCNT are plotted according to the original and developed models. Furthermore, the effects of φp and various interfacial/interphase parameters on the PCNT tensile strength are presented through contour plots. The tensile modulus and strength of PCNT show a threshold at low φp values, indicating the important effect of the percolation behavior on the mechanical properties. Poor mechanical performances are seen at high φp values and different ranges of interfacial/interphase parameters. However, the lowest φp values and the highest ranges of interfacial/interphase parameters result in the most desirable PCNT strength.

  4. Tissue damage thresholds during therapeutic electrical stimulation (United States)

    Cogan, Stuart F.; Ludwig, Kip A.; Welle, Cristin G.; Takmakov, Pavel


    Objective. Recent initiatives in bioelectronic modulation of the nervous system by the NIH (SPARC), DARPA (ElectRx, SUBNETS) and the GlaxoSmithKline Bioelectronic Medicines effort are ushering in a new era of therapeutic electrical stimulation. These novel therapies are prompting a re-evaluation of established electrical thresholds for stimulation-induced tissue damage. Approach. In this review, we explore what is known and unknown in published literature regarding tissue damage from electrical stimulation. Main results. For macroelectrodes, the potential for tissue damage is often assessed by comparing the intensity of stimulation, characterized by the charge density and charge per phase of a stimulus pulse, with a damage threshold identified through histological evidence from in vivo experiments as described by the Shannon equation. While the Shannon equation has proved useful in assessing the likely occurrence of tissue damage, the analysis is limited by the experimental parameters of the original studies. Tissue damage is influenced by factors not explicitly incorporated into the Shannon equation, including pulse frequency, duty cycle, current density, and electrode size. Microelectrodes in particular do not follow the charge per phase and charge density co-dependence reflected in the Shannon equation. The relevance of these factors to tissue damage is framed in the context of available reports from modeling and in vivo studies. Significance. It is apparent that emerging applications, especially with microelectrodes, will require clinical charge densities that exceed traditional damage thresholds. Experimental data show that stimulation at higher charge densities can be achieved without causing tissue damage, suggesting that safety parameters for microelectrodes might be distinct from those defined for macroelectrodes. However, these increased charge densities may need to be justified by bench, non-clinical or clinical testing to provide evidence of device

  5. Threshold dose distributions for 5 major allergenic foods in children

    NARCIS (Netherlands)

    Blom, W.M.; Vlieg-Boerstra, B.J.; Kruizinga, A.G.; Heide, S. van der; Houben, G.F.; Dubois, A.E.J.


    Background: For most allergenic foods, insufficient threshold dose information within the population restricts the advice on levels of unintended allergenic foods which should trigger precautionary labeling on prepackaged foods. Objective: We wanted to derive threshold dose distributions for major

  6. Threshold dose distributions for 5 major allergenic foods in children

    NARCIS (Netherlands)

    Blom, W. Marty; Vlieg-Boerstra, Berber J.; Kruizinga, Astrid G.; van der Heide, Sicco; Houben, Geert F.; Dubois, Anthony E. J.

    Background: For most allergenic foods, insufficient threshold dose information within the population restricts the advice on levels of unintended allergenic foods which should trigger precautionary labeling on prepackaged foods. Objective: We wanted to derive threshold dose distributions for major

  7. Category 3 threshold quantities for hazard categorization of nonreactor facilities

    Energy Technology Data Exchange (ETDEWEB)

    Mandigo, R.L.


    This document provides the information necessary to determine Hazard Category 3 threshold quantities for those isotopes of interest not listed in WHC-CM-4-46, Section 4, Table 1.''Threshold Quantities.''

  8. Multiuser switched diversity scheduling systems with per-user threshold

    KAUST Repository

    Nam, Haewoon


    A multiuser switched diversity scheduling scheme with per-user feedback threshold is proposed and analyzed in this paper. The conventional multiuser switched diversity scheduling scheme uses a single feedback threshold for every user, where the threshold is a function of the average signal-to-noise ratios (SNRs) of the users as well as the number of users involved in the scheduling process. The proposed scheme, however, constructs a sequence of feedback thresholds instead of a single feedback threshold such that each user compares its channel quality with the corresponding feedback threshold in the sequence. Numerical and simulation results show that thanks to the flexibility of threshold selection, where a potentially different threshold can be used for each user, the proposed scheme provides a higher system capacity than that for the conventional scheme. © 2006 IEEE.

  9. Double threshold discriminator for timing measurements

    International Nuclear Information System (INIS)

    Frolov, A.R.; Oslopova, T.V.; Pestov, Yu.N.


    The new type of a discriminator is based on the idea of simultaneous time measurements at two different thresholds for each pulse. Instead of using two independent electronic TDC channels this discriminator produces an output pulse with the timing taking into account the information from two time measurements ''on-line''. The operation principle, analytical calculations and experimental results are presented. The time walk of the discriminator at the level of 10 ps in the range of the input pulse height of 0.2-1.5 V has been obtained. ((orig.))

  10. Concentrating lightguide for threshold Cherenkov counters

    International Nuclear Information System (INIS)

    Gavrishchuk, O.P.; Onuchin, V.A.; Semenov, V.K.; Suzdalev, V.I.


    A method of manufacturing lightguides (Winston lenses) is proposed to increase the effective area of light collection on photodetectors (with diameter of detectiving area from 45 to 120 mm) and to broaden angular range of radiation detection in threshold Cherenkov counters. The concentrating lightguides with height and diameter up to 300 mm were pressure formed of 3 to 5 mm thick plexiglass sheets. Dependences of the light reflection coefficient on the wavelength (for wavelengths between 185 and 650 nm) of the deposited lightguide are presented. 10 refs.; 4 figs

  11. Superstring threshold corrections to Yukawa couplings

    International Nuclear Information System (INIS)

    Antoniadis, I.; Taylor, T.R.


    A general method of computing string corrections to the Kaehler metric and Yukawa couplings is developed at the one-loop level for a general compactification of the heterotic superstring theory. It also provides a direct determination of the so-called Green-Schwarz term. The matter metric has an infrared divergent part which reproduces the field-theoretical anomalous dimensions, and a moduli-dependent part which gives rise to threshold corrections in the physical Yukawa couplings. Explicit expressions are derived for symmetric orbifold compactifications. (author). 20 refs

  12. Computational analysis of thresholds for magnetophosphenes

    International Nuclear Information System (INIS)

    Laakso, Ilkka; Hirata, Akimasa


    In international guidelines, basic restriction limits on the exposure of humans to low-frequency magnetic and electric fields are set with the objective of preventing the generation of phosphenes, visual sensations of flashing light not caused by light. Measured data on magnetophosphenes, i.e. phosphenes caused by a magnetically induced electric field on the retina, are available from volunteer studies. However, there is no simple way for determining the retinal threshold electric field or current density from the measured threshold magnetic flux density. In this study, the experimental field configuration of a previous study, in which phosphenes were generated in volunteers by exposing their heads to a magnetic field between the poles of an electromagnet, is computationally reproduced. The finite-element method is used for determining the induced electric field and current in five different MRI-based anatomical models of the head. The direction of the induced current density on the retina is dominantly radial to the eyeball, and the maximum induced current density is observed at the superior and inferior sides of the retina, which agrees with literature data on the location of magnetophosphenes at the periphery of the visual field. On the basis of computed data, the macroscopic retinal threshold current density for phosphenes at 20 Hz can be estimated as 10 mA m −2 (−20% to  + 30%, depending on the anatomical model); this current density corresponds to an induced eddy current of 14 μA (−20% to  + 10%), and about 20% of this eddy current flows through each eye. The ICNIRP basic restriction limit for the induced electric field in the case of occupational exposure is not exceeded until the magnetic flux density is about two to three times the measured threshold for magnetophosphenes, so the basic restriction limit does not seem to be conservative. However, the reasons for the non-conservativeness are purely technical: removal of the highest 1% of

  13. 14-channel threshold gas Cerenkov counter

    International Nuclear Information System (INIS)

    Voichishin, M.N.; Devitsin, E.G.; Gus'kov, B.N.; Kapishin, M.N.; Zavertyaev, M.V.; Zinchenko, A.I.


    A 14-channel threshold gas Cerenkov counter filled with Freon-12 at a pressure of 1 atm is described. The radiator length is 150 cm. The counter efficiency for protons with a momentum of circa equal to or greater than 30 GeV/c exceeds 98%. The counter is a part of the system for identification of secondary charged particles of the BIS-2 spectrometer of the Institute of HighEnergy Physics. A diagram of the counter and its dimensions is shown. The counter consists of a light- and gasproof housing, a set of focusing mirrors, and a photomultiplier system

  14. Technology Thresholds for Microgravity: Status and Prospects (United States)

    Noever, D. A.


    The technological and economic thresholds for microgravity space research are estimated in materials science and biotechnology. In the 1990s, the improvement of materials processing has been identified as a national scientific priority, particularly for stimulating entrepreneurship. The substantial US investment at stake in these critical technologies includes six broad categories: aerospace, transportation, health care, information, energy, and the environment. Microgravity space research addresses key technologies in each area. The viability of selected space-related industries is critically evaluated and a market share philosophy is developed, namely that incremental improvements in a large markets efficiency is a tangible reward from space-based research.

  15. Norm based Threshold Selection for Fault Detectors

    DEFF Research Database (Denmark)

    Rank, Mike Lind; Niemann, Henrik


    The design of fault detectors for fault detection and isolation (FDI) in dynamic systems is considered from a norm based point of view. An analysis of norm based threshold selection is given based on different formulations of FDI problems. Both the nominal FDI problem as well as the uncertain FDI...... problem are considered. Based on this analysis, a performance index based on norms of the involved transfer functions is given. The performance index allows us also to optimize the structure of the fault detection filter directly...

  16. Regulamentação pública e conduta das firmas no sistema agroindustrial da borracha natural entre 1997 e 2000 Regulation and behavior of firms in Brazil's natural rubber agro-industrial system between 1997-2000

    Directory of Open Access Journals (Sweden)

    Augusto Hauber Gamero


    Full Text Available A necessidade de regulamentação no sistema agroindustrial (SAG da borracha natural no Brasil é evidente. Desde a metade do século, quando o país passou a importar esse produto, vários esforços governamentais vêm sendo definidos, objetivando o desenvolvimento sustentável do setor da produção agrícola nacional de borracha. No ano de 1997, criou-se uma política de subvenção direta à produção. Dada a estrutura desse SAG, associada à conjuntura do mercado internacional e a uma regulamentação falha do governo federal, começaram a surgir indícios de abuso de poder de mercado pela indústria pneumática instalada no país, principal consumidora do produto. Utilizando o arcabouço teórico da organização industrial, neste artigo se procurou levantar evidências nesse sentido.The need for regulation of Brazil’s natural rubber agro-industrial system (SAG is evident. Since the middle of the 20th century, when the country began importing rubber, many governmental efforts have been made to promote the sustainable development of Brazil’s natural rubber productive sector. In 1997, the Brazilian government created a direct subvention policy to assist rubber producers. Given the structure of Brazil’s SAG, the international rubber market, and imperfect regulation by the Federal Government, it would not be unexpected to find signs that Brazil’s largest natural rubber consumer, the domestic tire industry, has begun to abusively exercise its market power. Using the theoretical structure of Industrial Organization, this paper tries to show evidences of this abuse.

  17. Assessment of hearing threshold in adults with hearing loss using an automated system of cortical auditory evoked potential detection. (United States)

    Durante, Alessandra Spada; Wieselberg, Margarita Bernal; Roque, Nayara; Carvalho, Sheila; Pucci, Beatriz; Gudayol, Nicolly; de Almeida, Kátia

    The use of hearing aids by individuals with hearing loss brings a better quality of life. Access to and benefit from these devices may be compromised in patients who present difficulties or limitations in traditional behavioral audiological evaluation, such as newborns and small children, individuals with auditory neuropathy spectrum, autism, and intellectual deficits, and in adults and the elderly with dementia. These populations (or individuals) are unable to undergo a behavioral assessment, and generate a growing demand for objective methods to assess hearing. Cortical auditory evoked potentials have been used for decades to estimate hearing thresholds. Current technological advances have lead to the development of equipment that allows their clinical use, with features that enable greater accuracy, sensitivity, and specificity, and the possibility of automated detection, analysis, and recording of cortical responses. To determine and correlate behavioral auditory thresholds with cortical auditory thresholds obtained from an automated response analysis technique. The study included 52 adults, divided into two groups: 21 adults with moderate to severe hearing loss (study group); and 31 adults with normal hearing (control group). An automated system of detection, analysis, and recording of cortical responses (HEARLab ® ) was used to record the behavioral and cortical thresholds. The subjects remained awake in an acoustically treated environment. Altogether, 150 tone bursts at 500, 1000, 2000, and 4000Hz were presented through insert earphones in descending-ascending intensity. The lowest level at which the subject detected the sound stimulus was defined as the behavioral (hearing) threshold (BT). The lowest level at which a cortical response was observed was defined as the cortical electrophysiological threshold. These two responses were correlated using linear regression. The cortical electrophysiological threshold was, on average, 7.8dB higher than the

  18. Let's Burn Them All: Reflections on the Learning-Inhibitory Nature of Introduction to Management and Introduction to Organizational Behavior Textbooks (United States)

    Snyder, Robert A.


    This essay provides evidence from the neurosciences that standard Introduction to Management and "Introduction to Organizational Behavior" textbooks may inhibit, rather than facilitate, learning of the basic concepts and the rudimentary knowledge-basis that underlie the complex skills business students should learn in subsequent…

  19. Statistical Algorithm for the Adaptation of Detection Thresholds

    DEFF Research Database (Denmark)

    Stotsky, Alexander A.


    Many event detection mechanisms in spark ignition automotive engines are based on the comparison of the engine signals to the detection threshold values. Different signal qualities for new and aged engines necessitate the development of an adaptation algorithm for the detection thresholds...... remains constant regardless of engine age and changing detection threshold values. This, in turn, guarantees the same event detection performance for new and aged engines/sensors. Adaptation of the engine knock detection threshold is given as an example. Udgivelsesdato: 2008...

  20. Estimating the Threshold Level of Inflation for Thailand


    JIRANYAKUL, Komain


    Abstract. This paper analyzes the relationship between inflation and economic growth in Thailand using annual dataset during 1990 and 2015. The threshold model is estimated for different levels of threshold inflation rate. The results suggest that the threshold level of inflation above which inflation significantly slow growth is estimated at 3 percent. The negative relationship between inflation and growth is apparent above this threshold level of inflation. In other words, the inflation rat...