WorldWideScience

Sample records for models lfv persists

  1. Persistent Modelling

    DEFF Research Database (Denmark)

    2012-01-01

    on this subject, this book makes essential reading for anyone considering new ways of thinking about architecture. In drawing upon both historical and contemporary perspectives this book provides evidence of the ways in which relations between representation and the represented continue to be reconsidered......The relationship between representation and the represented is examined here through the notion of persistent modelling. This notion is not novel to the activity of architectural design if it is considered as describing a continued active and iterative engagement with design concerns – an evident...... characteristic of architectural practice. But the persistence in persistent modelling can also be understood to apply in other ways, reflecting and anticipating extended roles for representation. This book identifies three principle areas in which these extensions are becoming apparent within contemporary...

  2. Persistent Modelling

    DEFF Research Database (Denmark)

    on this subject, this book makes essential reading for anyone considering new ways of thinking about architecture. In drawing upon both historical and contemporary perspectives this book provides evidence of the ways in which relations between representation and the represented continue to be reconsidered......The relationship between representation and the represented is examined here through the notion of persistent modelling. This notion is not novel to the activity of architectural design if it is considered as describing a continued active and iterative engagement with design concerns – an evident...... characteristic of architectural practice. But the persistence in persistent modelling can also be understood to apply in other ways, reflecting and anticipating extended roles for representation. This book identifies three principle areas in which these extensions are becoming apparent within contemporary...

  3. Persistent Modelling

    DEFF Research Database (Denmark)

    practice: the duration of active influence that representation can hold in relation to the represented; the means, methods and media through which representations are constructed and used; and what it is that is being represented. Featuring contributions from some of the world’s most advanced thinkers....... It also provides critical insight into the use of contemporary modelling tools and methods, together with an examination of the implications their use has within the territories of architectural design, realisation and experience....

  4. In-flight cLFV conversion: {e-μ }, {e-τ } and {μ -τ } in minimal extensions of the standard model with sterile fermions

    Science.gov (United States)

    Abada, A.; De Romeri, V.; Orloff, J.; Teixeira, A. M.

    2017-05-01

    We revisit charged lepton flavour in-flight conversions, in which a beam of electrons or muons is directed onto a fixed target, e + N → μ +N, e + N → τ +N and μ + N → τ +N, focusing on elastic interactions with a nucleus N. After a general discussion of this observable, we carry a full phenomenological analysis in the framework of minimal Standard Model extensions via sterile neutrinos, with a strong emphasis on the rôle of the increasingly more stringent constraints arising from other (low-energy) charged lepton flavour-violation observables. Despite the potential interest of this observable, in particular in the light of certain upcoming facilities with the capability of very intense lepton beams, our study suggests that due to current bounds on three-body decays (ℓ _i → 3 ℓ _j) and μ -e conversion in nuclei, the expected number of conversions in such a minimal framework is dramatically reduced. An experimental observation of such a conversion would thus signal the presence of another source of flavour violation, possibly at tree level.

  5. Introduction: Persistent Modelling

    DEFF Research Database (Denmark)

    Ayres, Phil

    2012-01-01

    of this relationship is becoming increasingly variegated. This is apparent in three principle areas; the duration of active influence that representation can hold in relation to the represented; the means, methods and media through which representations are constructed and used; what it is that is being represented.......This introduction to 'Persistent Modelling – an extended role for architectural representation' identifies how the book probes the relationship between representation and the represented, in an architectural context. It discusses how the book presents an examination and discussion of historical......, familiar contemporary and, perhaps, not so familiar emerging manifestations of this relation. What persists from this probing, fully intact, is that representation and the represented remain inextricably related in our contemporary and emerging practices. What comes into focus is that the nature...

  6. Impact of sterile neutrinos on nuclear-assisted cLFV processes

    Energy Technology Data Exchange (ETDEWEB)

    Abada, A. [Laboratoire de Physique Théorique, CNRS,University Paris-Sud, Université Paris-Saclay, 91405 Orsay (France); Romeri, V. De; Teixeira, A.M. [Laboratoire de Physique Corpusculaire, CNRS/IN2P3 - UMR 6533,Campus des Cézeaux, 24 Av. des Landais, F-63177 Aubière Cedex (France)

    2016-02-12

    We discuss charged lepton flavour violating processes occurring in the presence of muonic atoms, such as muon-electron conversion in nuclei CR(μ−e, N), the (Coulomb enhanced) decay of muonic atoms into a pair of electrons BR(μ{sup −}e{sup −}→e{sup −}e{sup −}, N), as well as Muonium conversion and decay, Mu− (Mu)-bar and Mu→e{sup +}e{sup −}. Any experimental signal of these observables calls for scenarios of physics beyond the Standard Model. In this work, we consider minimal extensions of the Standard Model via the addition of sterile fermions, providing the corresponding complete analytical expressions for all the considered observables. We first consider an “ad hoc” extension with a single sterile fermion state, and investigate its impact on the above observables. Two well motivated mechanisms of neutrino mass generation are then considered: the Inverse Seesaw embedded into the Standard Model, and the νMSM. Our study reveals that, depending on their mass range and on the active-sterile mixing angles, sterile neutrinos can give significant contributions to the above mentioned observables, some of them even lying within present and future sensitivity of dedicated cLFV experiments. We complete the analysis by confronting our results to other (direct and indirect) searches for sterile fermions.

  7. A model for persistency of egg production

    NARCIS (Netherlands)

    Grossman, M.; Gossman, T.N.; Koops, W.J.

    2000-01-01

    The objectives of our study were to propose a new definition for persistency of egg production and to develop a mathematical model to describe the egg production curve, one that includes a new measure for persistency, based on the proposed definition, for use as a selection criterion to improve

  8. Modelling persistence in annual Australia point rainfall

    Directory of Open Access Journals (Sweden)

    J. P. Whiting

    2003-01-01

    Full Text Available Annual rainfall time series for Sydney from 1859 to 1999 is analysed. Clear evidence of nonstationarity is presented, but substantial evidence for persistence or hidden states is more elusive. A test of the hypothesis that a hidden state Markov model reduces to a mixture distribution is presented. There is strong evidence of a correlation between the annual rainfall and climate indices. Strong evidence of persistence of one of these indices, the Pacific Decadal Oscillation (PDO, is presented together with a demonstration that this is better modelled by fractional differencing than by a hidden state Markov model. It is shown that conditioning the logarithm of rainfall on PDO, the Southern Oscillation index (SOI, and their interaction provides realistic simulation of rainfall that matches observed statistics. Similar simulation models are presented for Brisbane, Melbourne and Perth. Keywords: Hydrological persistence,hidden state Markov models, fractional differencing, PDO, SOI, Australian rainfall

  9. Persistent agents in Axelrod's social dynamics model

    Science.gov (United States)

    Reia, Sandro M.; Neves, Ubiraci P. C.

    2016-01-01

    Axelrod's model of social dynamics has been studied under the effect of external media. Here we study the formation of cultural domains in the model by introducing persistent agents. These are agents whose cultural traits are not allowed to change but may be spread through local neighborhood. In the absence of persistent agents, the system is known to present a transition from a monocultural to a multicultural regime at some critical Q (number of traits). Our results reveal a dependence of critical Q on the occupation probability p of persistent agents and we obtain the phase diagram of the model in the (p,Q) -plane. The critical locus is explained by the competition of two opposite forces named here barrier and bonding effects. Such forces are verified to be caused by non-persistent agents which adhere (adherent agents) to the set of traits of persistent ones. The adherence (concentration of adherent agents) as a function of p is found to decay for constant Q. Furthermore, adherence as a function of Q is found to decay as a power law with constant p.

  10. Persistence Modeling for Assessing Marketing Strategy Performance

    NARCIS (Netherlands)

    M.G. Dekimpe (Marnik); D.M. Hanssens (Dominique)

    2003-01-01

    textabstractThe question of long-run market response lies at the heart of any marketing strategy that tries to create a sustainable competitive advantage for the firm or brand. A key challenge, however, is that only short-run results of marketing actions are readily observable. Persistence modeling

  11. Modeling global persistent organic chemicals in clouds

    Science.gov (United States)

    Mao, Xiaoxuan; Gao, Hong; Huang, Tao; Zhang, Lisheng; Ma, Jianmin

    2014-10-01

    A cloud model was implemented in a global atmospheric transport model to simulate cloud liquid water content and quantify the influence of clouds on gas/aqueous phase partitioning of persistent organic chemicals (POCs). Partitioning fractions of gas/aqueous and particle phases in clouds for three POCs α-hexachlorocyclohexane (α-HCH), polychlorinated biphenyl-28 (PCB-28), and PCB-138 in a cloudy atmosphere were estimated. Results show that the partition fraction of these selected chemicals depend on cloud liquid water content (LWC) and air temperature. We calculated global distribution of water droplet/ice particle-air partitioning coefficients of the three chemicals in clouds. The partition fractions at selected model grids in the Northern Hemisphere show that α-HCH, a hydrophilic chemical, is sorbed strongly onto cloud water droplets. The computed partition fractions at four selected model grids show that α-HCH tends to be sorbed onto clouds over land (source region) from summer to early fall, and over ocean from late spring to early fall. 20-60% of α-HCH is able to be sorbed to cloud waters over mid-latitude oceans during summer days. PCB-138, one of hydrophobic POCs, on the other hand, tends to be sorbed to particles in the atmosphere subject to air temperature. We also show that, on seasonal or annual average, 10-20% of averaged PCB-28 over the Northern Hemisphere could be sorbed onto clouds, leading to reduction of its gas-phase concentration in the atmosphere.

  12. Regional Persistent Organic Pollutants' Environmental Impact Assessment and Control Model

    Directory of Open Access Journals (Sweden)

    Jurgis Staniskis

    2008-10-01

    Full Text Available The sources of formation, environmental distribution and fate of persistent organic pollutants (POPs are increasingly seen as topics to be addressed and solved at the global scale. Therefore, there are already two international agreements concerning persistent organic pollutants: the Protocol of 1998 to the 1979 Convention on the Long-Range Transboundary Air Pollution on Persistent Organic Pollutants (Aarhus Protocol; and the Stockholm Convention on Persistent Organic Pollutants. For the assessment of environmental pollution of POPs, for the risk assessment, for the evaluation of new pollutants as potential candidates to be included in the POPs list of the Stokholmo or/and Aarhus Protocol, a set of different models are developed or under development. Multimedia models help describe and understand environmental processes leading to global contamination through POPs and actual risk to the environment and human health. However, there is a lack of the tools based on a systematic and integrated approach to POPs management difficulties in the region.

  13. Modeling and forecasting persistent financial durations

    Czech Academy of Sciences Publication Activity Database

    Žikeš, F.; Baruník, Jozef; Shenai, N.

    2017-01-01

    Roč. 36, č. 10 (2017), s. 1081-1110 ISSN 0747-4938 R&D Projects: GA ČR GA13-32263S Institutional support: RVO:67985556 Keywords : Long memory * multifractal models * price durations * realized volatility * whittle estimation Subject RIV: AH - Economics OBOR OECD: Finance Impact factor: 1.333, year: 2016 http://library.utia.cas.cz/separaty/2017/E/barunik-0478483.pdf

  14. Modeling and Forecasting Persistent Financial Durations

    Czech Academy of Sciences Publication Activity Database

    Žikeš, F.; Baruník, Jozef; Shenai, N.

    2017-01-01

    Roč. 36, č. 10 (2017), s. 1081-1110 ISSN 0747-4938 R&D Projects: GA ČR GA13-32263S EU Projects: European Commission 612955 - FINMAP Institutional support: RVO:67985556 Keywords : price durations * long memory * multifractal models * realized volatility * Whittle estimation Subject RIV: AH - Economics OBOR OECD: Applied Economics, Econometrics Impact factor: 1.333, year: 2016 http://library.utia.cas.cz/separaty/2014/E/barunik-0434201.pdf

  15. Modeling mechanisms of persisting and resolving delay in language development.

    Science.gov (United States)

    Thomas, Michael S C; Knowland, V C P

    2014-04-01

    PURPOSE In this study, the authors used neural network modeling to investigate the possible mechanistic basis of developmental language delay and to test the viability of the hypothesis that persisting delay and resolving delay lie on a mechanistic continuum with normal development. METHOD The authors used a population modeling approach to study individual rates of development in 1,000 simulated individuals acquiring a notional language domain (in this study, represented by English past tense). Variation was caused by differences in internal neurocomputational learning parameters as well as the richness of the language environment. An early language delay group was diagnosed, and individual trajectories were then traced. RESULTS Quantitative variations in learning mechanisms were sufficient to produce persisting delay and resolving delay subgroups in similar proportions to empirical observations. In the model, persisting language delay was caused by limitations in processing capacity, whereas resolving delay was caused by low plasticity. Richness of the language environment did not predict the emergence of persisting delay but did predict the final ability levels of individuals with resolving delay. CONCLUSION Mechanistically, it is viable that persisting delay and resolving delay are only quantitatively different. There may be an interaction between environmental factors and outcome groups, with individuals who have resolving delay being influenced more by the richness of the language environment.

  16. Building on Tinto's model of engagement and persistence ...

    African Journals Online (AJOL)

    Building on Tinto's model of engagement and persistence: Experiences from the Umthombo Youth Development Foundation Scholarship Scheme. A Ross. Abstract. Background. Major inequalities in staffing levels at rural and urban hospitals contribute to poorer health outcomes in rural areas. Local and international ...

  17. A psychological cascade model for persisting voice problems in teachers.

    NARCIS (Netherlands)

    Jong, F.I.C.R.S. de; Cornelis, B.E.; Wuyts, F.L.; Kooijman, P.G.C.; Schutte, H.K.; Oudes, M.J.; Graamans, K.

    2003-01-01

    In 76 teachers with persisting voice problems, the maintaining factors and coping strategies were examined. Physical, functional, psychological and socioeconomic factors were assessed. A parallel was drawn to a psychological cascade model designed for patients with chronic back pain. The majority of

  18. Persistence in a Two-Dimensional Moving-Habitat Model.

    Science.gov (United States)

    Phillips, Austin; Kot, Mark

    2015-11-01

    Environmental changes are forcing many species to track suitable conditions or face extinction. In this study, we use a two-dimensional integrodifference equation to analyze whether a population can track a habitat that is moving due to climate change. We model habitat as a simple rectangle. Our model quickly leads to an eigenvalue problem that determines whether the population persists or declines. After surveying techniques to solve the eigenvalue problem, we highlight three findings that impact conservation efforts such as reserve design and species risk assessment. First, while other models focus on habitat length (parallel to the direction of habitat movement), we show that ignoring habitat width (perpendicular to habitat movement) can lead to overestimates of persistence. Dispersal barriers and hostile landscapes that constrain habitat width greatly decrease the population's ability to track its habitat. Second, for some long-distance dispersal kernels, increasing habitat length improves persistence without limit; for other kernels, increasing length is of limited help and has diminishing returns. Third, it is not always best to orient the long side of the habitat in the direction of climate change. Evidence suggests that the kurtosis of the dispersal kernel determines whether it is best to have a long, wide, or square habitat. In particular, populations with platykurtic dispersal benefit more from a wide habitat, while those with leptokurtic dispersal benefit more from a long habitat. We apply our model to the Rocky Mountain Apollo butterfly (Parnassius smintheus).

  19. Career Persistence Model for Female Engineers in the Indonesian Context

    Directory of Open Access Journals (Sweden)

    Lies Dahlia

    2017-08-01

    Full Text Available Extant studies about female engineers have suggested their career persistency in the engineering career is influenced by the workplace, which is characterized by male dominated culture making them feel marginalized. In Indonesia, similar studies for reference are limited. This paper is based on an exploratory quantitative study using a questionnaire developed based on the Career Persistence Model. This paper is based on an empirical exploratory quantitative study by adopting Buse’s et al. Career Persistence Model (2013. The intention is to contribute to the literature in the context of Indonesia. It explores the Indonesian cultural dimensions and investigates their relationship to the roles of women in family, society and the workplace, and how women manage to navigate barriers to avoid taking alternative career paths. Contrary to extant studies, findings show women feel equally treated to men in the workplace, however some work demands may hinder. The strong acknowledgement of one’s roles in this collective society outdoes the opinions that the Islamic jurisprudence (fiqh has marginalized empowerment of women, resulting in gender-based injustices and discrimination. Future studies should look into social supports at the workplace in an attempt to retain and increase the share of women in the engineering career in Indonesia.

  20. Modelling Withdrawal and Persistence for Initial Teacher Training: Revising Tinto's Longitudinal Model of Departure

    Science.gov (United States)

    Roberts, Deborah

    2012-01-01

    This paper proposes a theoretical model to explain trainee withdrawal and persistence within higher education (HE) based initial teacher training (ITT). Within ITT, attrition and persistence are under-researched and under-theorised, thus providing the rationale for this study. Within HE more broadly, a number of models have been proposed, most…

  1. Disease Extinction Versus Persistence in Discrete-Time Epidemic Models.

    Science.gov (United States)

    van den Driessche, P; Yakubu, Abdul-Aziz

    2018-04-12

    We focus on discrete-time infectious disease models in populations that are governed by constant, geometric, Beverton-Holt or Ricker demographic equations, and give a method for computing the basic reproduction number, [Formula: see text]. When [Formula: see text] and the demographic population dynamics are asymptotically constant or under geometric growth (non-oscillatory), we prove global asymptotic stability of the disease-free equilibrium of the disease models. Under the same demographic assumption, when [Formula: see text], we prove uniform persistence of the disease. We apply our theoretical results to specific discrete-time epidemic models that are formulated for SEIR infections, cholera in humans and anthrax in animals. Our simulations show that a unique endemic equilibrium of each of the three specific disease models is asymptotically stable whenever [Formula: see text].

  2. Discrete persistent-chain model for protein binding on DNA.

    Science.gov (United States)

    Lam, Pui-Man; Zhen, Yi

    2011-04-01

    We describe and solve a discrete persistent-chain model of protein binding on DNA, involving an extra σ(i) at a site i of the DNA. This variable takes the value 1 or 0, depending on whether or not the site is occupied by a protein. In addition, if the site is occupied by a protein, there is an extra energy cost ɛ. For a small force, we obtain analytic expressions for the force-extension curve and the fraction of bound protein on the DNA. For higher forces, the model can be solved numerically to obtain force-extension curves and the average fraction of bound proteins as a function of applied force. Our model can be used to analyze experimental force-extension curves of protein binding on DNA, and hence deduce the number of bound proteins in the case of nonspecific binding. ©2011 American Physical Society

  3. Characterizing and modelling persistence in the number of lottery winners

    Science.gov (United States)

    Antonio, Fernando J.; Mendes, Renio S.; Itami, Andreia S.; Picoli, Sergio

    2015-06-01

    Lottery is the most famous branch among all the games of chance. By analysing data from Mega-Sena, the major lottery in Brazil, we investigated the presence of persistent behaviour in the time series of the number of winners. We found that the demand for tickets grew collectively as an exponential driven by the size of the accumulated jackpot. Finally, we identified that a stochastic model grounded on the rolling-over feature of lotteries can generate correlations qualitatively similar to those observed empirically. The model is consistent with the idea that the growth in the number of bets, motivated by the size of the expected jackpot, is a mechanism generator of correlations in an apparently random scenario.

  4. Exploring persistence in science in CEGEP: Toward a motivational model

    Science.gov (United States)

    Simon, Rebecca A.

    There is currently a shortage of science teachers in North America and continually decreasing rates of enrollment in science programs. Science continues to be the academic domain that sees the highest attrition rates, particularly for women. The purpose of the present study was to examine male and female students' experiences in mathematics and science courses during a crucial time in their academic development in an attempt to explain the high attrition rates in science between the last year of high school and the first year of CEGEP (junior college). In line with self-determination theory (Deci & Ryan, 1985), as well as achievement-goal theory (Pintrich & Schunk, 1996) and research on academic emotions, the study examined the relation between a set of motivational variables (i.e., perceptions of autonomy-support, self-efficacy, achievement goals, and intrinsic motivation), affect, achievement, and persistence. A secondary objective was to test a motivational model of student persistence in science using structural equation modeling (SEM). The sample consisted of 603 male and 706 female students from four English-language CEGEPs in the greater Montreal area. Just prior to beginning CEGEP, participants completed a questionnaire that asked about the learning environment in high school mathematics and science classes as well as student characteristics including sources of motivation, personal achievement goals, and feelings of competence. All students expressed an initial interest in pursuing a career in science by enrolling in optional advanced mathematics and science courses during high school. Multivariate analysis of variance was used to examine differences among male and female students across the variables measured. Structural equation modeling was used to test the validity of a questionnaire designed specifically to gather information about CEGEP students' experiences with mathematics and science, and to evaluate the fit of a model designed to reflect the

  5. A jump persistent turning walker to model zebrafish locomotion.

    Science.gov (United States)

    Mwaffo, Violet; Anderson, Ross P; Butail, Sachit; Porfiri, Maurizio

    2015-01-06

    Zebrafish are gaining momentum as a laboratory animal species for the investigation of several functional and dysfunctional biological processes. Mathematical models of zebrafish behaviour are expected to considerably aid in the design of hypothesis-driven studies by enabling preliminary in silico tests that can be used to infer possible experimental outcomes without the use of zebrafish. This study is motivated by observations of sudden, drastic changes in zebrafish locomotion in the form of large deviations in turn rate. We demonstrate that such deviations can be captured through a stochastic mean reverting jump diffusion model, a process that is commonly used in financial engineering to describe large changes in the price of an asset. The jump process-based model is validated on trajectory data of adult subjects swimming in a shallow circular tank obtained from an overhead camera. Through statistical comparison of the empirical distribution of the turn rate against theoretical predictions, we demonstrate the feasibility of describing zebrafish as a jump persistent turning walker. The critical role of the jump term is assessed through comparison with a simplified mean reversion diffusion model, which does not allow for describing the heavy-tailed distributions observed in the fish turn rate. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

  6. Who influenced inflation persistence in China? A comparative analysis of the standard CIA model and CIA model with endogenous money

    Directory of Open Access Journals (Sweden)

    Liao Ying

    2013-12-01

    Full Text Available In this paper, we examine the influencing factors of inflation persistence in China’s economy using the DSGE approach. Two monetary DSGE models are estimated, namely, a standard CIA model and a CIA model with a Taylor rule. This article uses the Bayesian method to estimate the model, and the estimated and inferred results are credible due to the Markov chain reaching convergence. The results show that the augmented model outperforms the standard CIA model in terms of capturing inflation persistence. Further studies show that inflation persistence mainly comes from the persistence of the money supply, while money supply uncertainty, the reaction coefficient of monetary growth to productivity, productivity persistence and productivity uncertainty have a smaller impact on inflation persistence. Changes of monetary policy have little effect on inflation persistence.

  7. Using latent selection difference to model persistence in a declining population.

    Directory of Open Access Journals (Sweden)

    Mara E Erickson

    Full Text Available Population persistence is a direct measure of the viability of a population. Monitoring the distribution of declining populations or subpopulations over time can yield estimates of persistence, which we show can be modeled as a latent selection difference (LSD contrasting attributes of sites where populations have persisted versus those that have not. Predicted persistence can be modeled with predictor covariates to identify factors correlated with species persistence. We demonstrate how to model persistence based on changes in occupancy that can include adjustments for detection probability. Using a known historical distribution of the western grebe (Aechmophorus occidentalis, we adapted methods originally developed for occupancy modeling to evaluate how environmental covariates including emergent vegetation and human developments have affected western grebe persistence in Alberta. The relative probability of persistence was correlated with the extent of shoreline bulrush (Scirpus lacustris, which is important vegetation for nesting cover. We also documented that western grebe populations were less likely to persist on lakes in the boreal forest, primarily located on the northern boundary of the species' range. Factors influencing occupancy were different than those determining persistence by western grebes; persistence and occupancy were not correlated. Persistence was more likely on lakes with recreational development, reflecting reliance by grebes on the larger, fish-bearing waterbodies that also are attractive for lakeshore development. Unfortunately, the correlation with recreational development on Alberta's lakes puts grebes at risk for loss of brood-rearing habitats--primary threats to altricial birds--if steps are not taken to prevent disturbance to bulrush stands. Identifying factors related to the persistence of a species--especially one in decline--is a fundamental step in conservation management.

  8. Using animal models to overcome temporal, spatial and combinatorial challenges in HIV persistence research

    DEFF Research Database (Denmark)

    Denton, Paul W.; Søgaard, Ole Schmeltz; Tolstrup, Martin

    2016-01-01

    will improve our understanding of HIV persistence and move the field closer to achieving eradication of persistent HIV. Given that humanized mice and non-human primate HIV models permit rigorous control of experimental conditions, these models have been used extensively as in vivo research platforms...

  9. Early marketing matters : A time-varying parameter approach to persistence modeling

    NARCIS (Netherlands)

    Osinga, E.C.; Leeflang, P.S.H.; Wieringa, J.E.

    Are persistent marketing effects most likely to appear right after the introduction of a product? The authors give an affirmative answer to this question by developing a model that explicitly reports how persistent and transient marketing effects evolve over time. The proposed model provides

  10. Modelling persistence in the conditional mean of inflation using the ...

    African Journals Online (AJOL)

    These results would, therefore, be useful to both countries in making good portfolio decisions, assessing the efficacy of a monetary policy or programme meant to control inflation persistence and also serving as a tool for detecting volatility and its impact, for the Ghanaian and South African inflation rates and their economies ...

  11. Predictive features of persistent activity emergence in regular spiking and intrinsic bursting model neurons.

    Directory of Open Access Journals (Sweden)

    Kyriaki Sidiropoulou

    Full Text Available Proper functioning of working memory involves the expression of stimulus-selective persistent activity in pyramidal neurons of the prefrontal cortex (PFC, which refers to neural activity that persists for seconds beyond the end of the stimulus. The mechanisms which PFC pyramidal neurons use to discriminate between preferred vs. neutral inputs at the cellular level are largely unknown. Moreover, the presence of pyramidal cell subtypes with different firing patterns, such as regular spiking and intrinsic bursting, raises the question as to what their distinct role might be in persistent firing in the PFC. Here, we use a compartmental modeling approach to search for discriminatory features in the properties of incoming stimuli to a PFC pyramidal neuron and/or its response that signal which of these stimuli will result in persistent activity emergence. Furthermore, we use our modeling approach to study cell-type specific differences in persistent activity properties, via implementing a regular spiking (RS and an intrinsic bursting (IB model neuron. We identify synaptic location within the basal dendrites as a feature of stimulus selectivity. Specifically, persistent activity-inducing stimuli consist of activated synapses that are located more distally from the soma compared to non-inducing stimuli, in both model cells. In addition, the action potential (AP latency and the first few inter-spike-intervals of the neuronal response can be used to reliably detect inducing vs. non-inducing inputs, suggesting a potential mechanism by which downstream neurons can rapidly decode the upcoming emergence of persistent activity. While the two model neurons did not differ in the coding features of persistent activity emergence, the properties of persistent activity, such as the firing pattern and the duration of temporally-restricted persistent activity were distinct. Collectively, our results pinpoint to specific features of the neuronal response to a given

  12. How to diagnose rheumatoid arthritis early: a prediction model for persistent (erosive) arthritis

    NARCIS (Netherlands)

    Visser, Henk; le Cessie, Saskia; Vos, Koen; Breedveld, Ferdinand C.; Hazes, Johanna M. W.

    2002-01-01

    To develop a clinical model for the prediction, at the first visit, of 3 forms of arthritis outcome: self-limiting, persistent nonerosive, and persistent erosive arthritis. A standardized diagnostic evaluation was performed on 524 consecutive, newly referred patients with early arthritis.

  13. Persistency of lactation using random regression models and different fixed regression modeling approaches

    Directory of Open Access Journals (Sweden)

    Jaime Araujo Cobuci

    2012-09-01

    Full Text Available Milk yield test-day records on the first three lactations of 25,500 Holstein cows were used to estimate genetic parameters and predict breeding values for nine measures of persistency and 305-d milk yield in a random regression animal model using two criteria to define the fixed regression. Legendre polynomials of fourth and fifth orders were used to model the fixed and random regressions of lactation curves. The fixed regressions were adjusted for average milk yield on populations (single or subpopulations (multiple formed by cows that calved at the same age and in the same season. Akaike Information (AIC and Bayesian Information (BIC criteria indicated that models with multiple regression lactation curves had the best fit to test-day milk records of first lactations, while models with a single regression curve had the best fit for the second and third lactations. Heritability and genetic correlation estimates between persistency and milk yield differed significantly depending on the lactation order and the measures of persistency used. These parameters did not differ significantly depending on the criteria used for defining the fixed regressions for lactation curves. In general, the heritability estimates were higher for first (0.07 to 0.43, followed by the second (0.08 to 0.21 and third (0.04 to 0.10 lactation. The rank of sires resulting from the processes of genetic evaluation for milk yield or persistency using random regression models differed according to the criteria used for determining the fixed regression of lactation curve.

  14. Multivariate prognostic modeling of persistent pain following lumbar discectomy.

    LENUS (Irish Health Repository)

    Hegarty, Dominic

    2013-03-04

    Persistent postsurgical pain (PPSP) affects between 10% and 50% of surgical patients, the development of which is a complex and poorly understood process. To date, most studies on PPSP have focused on specific surgical procedures where individuals do not suffer from chronic pain before the surgical intervention. Individuals who have a chronic nerve injury are likely to have established peripheral and central sensitization which may increase the risk of developing PPSP. Concurrent analyses of the possible factors contributing to the development of PPSP following lumbar discectomy have not been examined.

  15. Modified Bean Model and FEM Method Combined for Persistent Current Calculation in Superconducting Coils

    CERN Document Server

    Völlinger, Christine; Russenschuck, Stephan

    2001-01-01

    Field variations in the LHC superconducting magnets, e. g. during the ramping of the magnets, induce magnetization currents in the superconducting material, the so-called persistent currents that do not decay but persist due to the lack of resistivity. This paper describes a semi-analytical hysteresis model for hard superconductors, which has been developed for the computation of the total field errors arising from persistent currents. Since the superconducting coil is surrounded by a ferromagnetic yoke structure, the persistent current model is combined with the finite element method (FEM), as the non-linear yoke can only be calculated numerically. The used finite element method is based on a reduced vector potential formulation that avoids the meshing of the coil while calculating the part of the field arising from the source currents by means of the Biot-Savart Law. The combination allows to determine persistent current induced field errors as function of the excitation and for arbitrarily shaped iron yoke...

  16. Precision tests of the Standard Model with Kaon decays at CERN

    Science.gov (United States)

    Lamanna, G.; Ambrosino, F.; Antonelli, A.; Anzivino, G.; Arcidiacono, R.; Baldini, W.; Balev, S.; Batley, J. R.; Behler, M.; Bifani, S.; Biino, C.; Bizzeti, A.; Bloch-Devaux, B.; Bocquet, G.; Bolotov, V.; Bucci, F.; Cabibbo, N.; Calvetti, M.; Cartiglia, N.; Ceccucci, A.; Cenci, P.; Cerri, C.; Cheshkov, C.; Chèze, J. B.; Clemencic, M.; Collazuol, G.; Costantini, F.; Cotta Ramusino, A.; Coward, D.; Cundy, D.; Dabrowski, A.; D'Agostini, G.; Dalpiaz, P.; Damiani, C.; Danielsson, H.; De Beer, M.; Dellacasa, G.; Derré, J.; Dibon, H.; Di Filippo, D.; DiLella, L.; Doble, N.; Duk, V.; Engelfried, J.; Eppard, K.; Falaleev, V.; Fantechi, R.; Fidecaro, M.; Fiorini, L.; Fiorini, M.; Fonseca Martin, T.; Frabetti, P. L.; Fucci, A.; Gallorini, S.; Gatignon, L.; Gersabeck, E.; Gianoli, A.; Giudici, S.; Gonidec, A.; Goudzovski, E.; Goy Lopez, S.; Gushchin, E.; Hallgren, B.; Hita-Hochgesand, M.; Holder, M.; Hristov, P.; Iacopini, E.; Imbergamo, E.; Jeitler, M.; Kalmus, G.; Kekelidze, V.; Kleinknecht, K.; Kozhuharov, V.; Kubischta, W.; Kurshetsov, V.; Lamanna, G.; Lazzeroni, C.; Lenti, M.; Leonardi, E.; Litov, L.; Madigozhin, D.; Maier, A.; Mannelli, I.; Marchetto, F.; Marel, G.; Markytan, M.; Marouelli, P.; Martini, M.; Masetti, L.; Massarotti, P.; Mazzucato, E.; Michetti, A.; Mikulec, I.; Misheva, M.; Molokanova, N.; Monnier, E.; Moosbrugger, U.; Morales Morales, C.; Moulson, M.; Movchan, S.; Munday, D. J.; Napolitano, M.; Nappi, A.; Neuhofer, G.; Norton, A.; Numao, T.; Obraztsov, V.; Palladino, V.; Patel, M.; Pepe, M.; Peters, A.; Petrucci, F.; Petrucci, M. C.; Peyaud, B.; Piandani, R.; Piccini, M.; Pierazzini, G.; Polenkevich, I.; Popov, I.; Potrebenikov, Yu.; Raggi, M.; Renk, B.; Retière, F.; Riedler, P.; Romano, A.; Rubin, P.; Ruggiero, G.; Salamon, A.; Saracino, G.; Savrié, M.; Scarpa, M.; Semenov, V.; Sergi, A.; Serra, M.; Shieh, M.; Shkarovskiy, S.; Slater, M. W.; Sozzi, M.; Spadaro, T.; Stoynev, S.; Swallow, E.; Szleper, M.; Valdata-Nappi, M.; Valente, P.; Vallage, B.; Velasco, M.; Veltri, M.; Venditti, S.; Wache, M.; Wahl, H.; Walker, A.; Wanke, R.; Widhalm, L.; Winhart, A.; Winston, R.; Wood, M. D.; Wotton, S. A.; Yushchenko, O.; Zinchenko, A.; Ziolkowski, M.; NA48/2 Collaboration; NA62 Collaboration

    2016-04-01

    Effects of new physics in flavor could be found both in Flavor Changing Neutral Current (FCNC) processes and in Lepton Flavor Violation (LFV) modes. The former offer the possibility to deeply test the standard model in a clean environment, while the latter are sensitive to contribution from several models beyond the standard model. In the Kaon sector both FCNC and LFV will be investigated in the NA62 experiment. In addition the kaons sector is an ideal place where to look for new particles and tiny effects, in the region of hundreds of MeV/c2. In this paper prospects for exotic searches in NA62 will be presented, together with recent results from NA48/2 and NA62-RK on LFV kaon decays modes.

  17. Neutrino Masses and Lepton-Flavor Violation in Supersymmetric Models with lopsided Froggatt-Nielsen charges

    CERN Document Server

    Sato, J; Sato, Joe; Tobe, Kazuhiro

    2001-01-01

    We analyze in detail lepton-flavor violation (LFV) in the charged-lepton sector such as $\\mu \\to e \\gamma$, $\\tau \\to \\mu \\gamma$, $\\mu \\to eee$ and the $\\mu \\to e$ conversion in nuclei, within the framework of supersymmetric models with lopsided Froggatt--Nielsen charges, in which the large mixing in the neutrino sector as well as small mixings in the quark sector can be naturally accommodated. We show that the present experimental limits on the LFV processes already exclude some of the models. The future proposed search for LFV, especially in muon processes, can provide a significant probe to this framework. We also stress the importance of the measurement of $U^{MNS}_{e3}$ in neutrino experiments, and the fact that the KamLAND experiment could play a significant role to test a certain class of models.

  18. Genetic evaluation for persistency of lactation in Holstein cows using a random regression model

    Directory of Open Access Journals (Sweden)

    Jaime Araujo Cobuci

    2007-03-01

    Full Text Available A model for analyzing test day records including both fixed and random coefficients was applied to the genetic evaluation of first lactation data for Holstein cows. Data comprising 87045 test-day milk yield records from calving between 1997 and 2001 from Holstein herds in 10 regions of the Brazilian state of Minas Gerais. Six persistency of lactation measures were evaluated using breeding values obtained by random regression analyses. The Wilmink function was used to model the additive genetic and permanent environmental effects. Residual variance was constant throughout lactation. Ranking for animals did not change among criteria for persistency measurements, but ranking changes were observed when the estimated breeding value (EBV for persistency of lactation was contrasted with those estimated for 305-day milk yield (305MY. The rank correlation estimates for persistency of lactation and 305MY were practically the same for sire and cows, and ranged from -0.45 to 0.69. The EBVs for milk yield during lactation for sires producing daughters with superior 305MY indicate genetic differences between sires regarding their ability to transmit desirable persistency of lactation traits. This suggests that selection for total lactation milk yield does not identify sires or cows that are genetically superior in regard to persistency of lactation. Genetic evaluation for persistency of lactation is important for improving the efficiency of the milk production capacity of Holstein cows.

  19. Modeling Exposure to Persistent Chemicals in Hazard and Risk Assessment

    Energy Technology Data Exchange (ETDEWEB)

    Cowan-Ellsberry, Christina E.; McLachlan, Michael S.; Arnot, Jon A.; MacLeod, Matthew; McKone, Thomas E.; Wania, Frank

    2008-11-01

    Fate and exposure modeling has not thus far been explicitly used in the risk profile documents prepared to evaluate significant adverse effect of candidate chemicals for either the Stockholm Convention or the Convention on Long-Range Transboundary Air Pollution. However, we believe models have considerable potential to improve the risk profiles. Fate and exposure models are already used routinely in other similar regulatory applications to inform decisions, and they have been instrumental in building our current understanding of the fate of POP and PBT chemicals in the environment. The goal of this paper is to motivate the use of fate and exposure models in preparing risk profiles in the POP assessment procedure by providing strategies for incorporating and using models. The ways that fate and exposure models can be used to improve and inform the development of risk profiles include: (1) Benchmarking the ratio of exposure and emissions of candidate chemicals to the same ratio for known POPs, thereby opening the possibility of combining this ratio with the relative emissions and relative toxicity to arrive at a measure of relative risk. (2) Directly estimating the exposure of the environment, biota and humans to provide information to complement measurements, or where measurements are not available or are limited. (3) To identify the key processes and chemical and/or environmental parameters that determine the exposure; thereby allowing the effective prioritization of research or measurements to improve the risk profile. (4) Predicting future time trends including how quickly exposure levels in remote areas would respond to reductions in emissions. Currently there is no standardized consensus model for use in the risk profile context. Therefore, to choose the appropriate model the risk profile developer must evaluate how appropriate an existing model is for a specific setting and whether the assumptions and input data are relevant in the context of the application

  20. Modelling the fate of persistent organic pollutants in Europe: parameterisation of a gridded distribution model

    International Nuclear Information System (INIS)

    Prevedouros, Konstantinos; MacLeod, Matthew; Jones, Kevin C.; Sweetman, Andrew J.

    2004-01-01

    A regionally segmented multimedia fate model for the European continent is described together with an illustrative steady-state case study examining the fate of γ-HCH (lindane) based on 1998 emission data. The study builds on the regionally segmented BETR North America model structure and describes the regional segmentation and parameterisation for Europe. The European continent is described by a 5 deg. x 5 deg. grid, leading to 50 regions together with four perimetric boxes representing regions buffering the European environment. Each zone comprises seven compartments including; upper and lower atmosphere, soil, vegetation, fresh water and sediment and coastal water. Inter-regions flows of air and water are described, exploiting information originating from GIS databases and other georeferenced data. The model is primarily designed to describe the fate of Persistent Organic Pollutants (POPs) within the European environment by examining chemical partitioning and degradation in each region, and inter-region transport either under steady-state conditions or fully dynamically. A test case scenario is presented which examines the fate of estimated spatially resolved atmospheric emissions of lindane throughout Europe within the lower atmosphere and surface soil compartments. In accordance with the predominant wind direction in Europe, the model predicts high concentrations close to the major sources as well as towards Central and Northeast regions. Elevated soil concentrations in Scandinavian soils provide further evidence of the potential of increased scavenging by forests and subsequent accumulation by organic-rich terrestrial surfaces. Initial model predictions have revealed a factor of 5-10 underestimation of lindane concentrations in the atmosphere. This is explained by an underestimation of source strength and/or an underestimation of European background levels. The model presented can further be used to predict deposition fluxes and chemical inventories, and it

  1. Stability and persistence in plankton models with distributed delays

    CERN Document Server

    Abdallah, S H

    2003-01-01

    In this paper a model with two independent distributed delays is proposed to describe a population of microorganism feeding on a limiting nutrient which is supplied at a constant rate and is recycled after the death of the species by decomposer action. We obtain sufficient conditions for local and global stability of the positive equilibrium of the model. A fairly general function for nutrient uptake is considered. Stability changes of the positive equilibrium as the nutrient supply increases are studied by the Hopf bifurcation theorem.

  2. Toward a Model of Vocational Persistence Among Seminarians: Part III

    Science.gov (United States)

    Lee, James L.

    1970-01-01

    Assumptions underlying model rely on Cartwright and Harary's (1960) definition of Heider's cognitive balance theory and Festinger's (1957) cognitive dissonance theory. Diagrams illustrate degree of balance between personal and reference group (curch authorities, classmates, family) attitudes. Parts I and II in earlier issues. (CJ)

  3. Stochastic population and epidemic models persistence and extinction

    CERN Document Server

    Allen, Linda J S

    2015-01-01

    This monograph provides a summary of the basic theory of branching processes for single-type and multi-type processes. Classic examples of population and epidemic models illustrate the probability of population or epidemic extinction obtained from the theory of branching processes. The first chapter develops the branching process theory, while in the second chapter two applications to population and epidemic processes of single-type branching process theory are explored. The last two chapters present multi-type branching process applications to epidemic models, and then continuous-time and continuous-state branching processes with applications. In addition, several MATLAB programs for simulating stochastic sample paths  are provided in an Appendix. These notes originated as part of a lecture series on Stochastics in Biological Systems at the Mathematical Biosciences Institute in Ohio, USA. Professor Linda Allen is a Paul Whitfield Horn Professor of Mathematics in the Department of Mathematics and Statistics ...

  4. Model-based assessment of persistence in proposed marine protected area designs.

    Science.gov (United States)

    Kaplan, David M; Botsford, Louis W; O'Farrell, Michael R; Gaines, Steven D; Jorgensen, Salvador

    2009-03-01

    Assessment of marine protected areas (MPAs) requires the ability to quantify the effects of proposed MPA size and placement, habitat distribution, larval dispersal, and fishing on the persistence of protected populations. Here we describe a model-based approach to assessment of the contribution of a network of marine protected areas to the persistence of populations with a sedentary adult phase and a dispersing larval phase. The model integrates the effects of a patchy spatial distribution of habitat, the spatial scale of larval dispersal, and the level of fishing outside of reserves into a calculation of the spatial distribution of equilibrium settlement. We use the amount of coastline predicted to have equilibrium settlement rates that saturate post-settlement habitat as a response variable for the assessment and comparison of MPA network designs. We apply this model to a set of recently proposed MPA networks for the central coast of California, USA. Results show that the area of habitat set aside is a good predictor of the area over which population levels will be high for short-distance dispersers. However, persistence of longer distance dispersers depends critically on the spatial distribution of habitat and reserves, ranging from not persistent anywhere to persistent over a greater area than that set aside in reserves. These results depend on the mechanisms of persistence, with self-replacement supporting short-distance dispersers and network effects supporting long-distance dispersers. Persistence also depends critically on fishery status outside the MPAs, as well as how fishing effort is redistributed after MPA implementation. This assessment method provides important benchmarks, as well as a transparent modeling approach, for improving initial MPA configurations that may result from less-comprehensive rule- or habitat-based methods of designing MPAs.

  5. Milk yield persistency in Brazilian Gyr cattle based on a random regression model.

    Science.gov (United States)

    Pereira, R J; Verneque, R S; Lopes, P S; Santana, M L; Lagrotta, M R; Torres, R A; Vercesi Filho, A E; Machado, M A

    2012-06-15

    With the objective of evaluating measures of milk yield persistency, 27,000 test-day milk yield records from 3362 first lactations of Brazilian Gyr cows that calved between 1990 and 2007 were analyzed with a random regression model. Random, additive genetic and permanent environmental effects were modeled using Legendre polynomials of order 4 and 5, respectively. Residual variance was modeled using five classes. The average lactation curve was modeled using a fourth-order Legendre polynomial. Heritability estimates for measures of persistency ranged from 0.10 to 0.25. Genetic correlations between measures of persistency and 305-day milk yield (Y305) ranged from -0.52 to 0.03. At high selection intensities for persistency measures and Y305, few animals were selected in common. As the selection intensity for the two traits decreased, a higher percentage of animals were selected in common. The average predicted breeding values for Y305 according to year of birth of the cows had a substantial annual genetic gain. In contrast, no improvement in the average persistency breeding value was observed. We conclude that selection for total milk yield during lactation does not identify bulls or cows that are genetically superior in terms of milk yield persistency. A measure of persistency represented by the sum of deviations of estimated breeding value for days 31 to 280 in relation to estimated breeding value for day 30 should be preferred in genetic evaluations of this trait in the Gyr breed, since this measure showed a medium heritability and a genetic correlation with 305-day milk yield close to zero. In addition, this measure is more adequate at the time of peak lactation, which occurs between days 25 and 30 after calving in this breed.

  6. Persistence of an SEIR Model with Immigration Dependent on the Prevalence of Infection

    Directory of Open Access Journals (Sweden)

    Wenjuan Wang

    2010-01-01

    Full Text Available We incorporate the immigration of susceptible individuals into an SEIR epidemic model, assuming that the immigration rate decreases as the spread of infection increases. For this model, the basic reproduction number, R0, is found, which determines that the disease is either extinct or persistent ultimately. The obtained results show that the disease becomes extinct as R01.

  7. The Role of Student Involvement and Perceptions of Integration in a Causal Model of Student Persistence.

    Science.gov (United States)

    Berger, Joseph B.; Milem, Jeffrey F.

    1999-01-01

    This study refined and applied an integrated model of undergraduate persistence (accounting for both behavioral and perceptual components) to examine first-year retention at a private, highly selective research university. Results suggest that including behaviorally based measures of involvement improves the model's explanatory power concerning…

  8. Screening of persistent organic pollutants by QSPR classification models: a comparative study.

    Science.gov (United States)

    Papa, Ester; Gramatica, Paola

    2008-08-01

    A Quantitative Structure-Property Relationships (QSPRs) study for the prediction of the environmental persistence of a set of 250 heterogeneous organic compounds is here presented. Three a priori defined classes of environmental persistence were generated, by Hierarchical Cluster Analysis, from the combination of half-life data in air, water, soil and sediment available for all the studied compounds. QSPR classification models were successfully developed using different techniques (k-NN, CART and CP-ANN) and three interpretable theoretical molecular descriptors. Robust external validation was provided by statistical splitting and also on completely new data. The good performances of all these models were compared and their structural domains were analyzed. The analysis of the errors highlights a slight tendency of persistence overestimation, misclassifying chemicals from a lower to a higher class of persistence, in line with the precautionary principle. Finally, the reliability of the proposed QSPR models was verified further with new data from the literature. The structure-based classification models, applicable for the prediction of potential persistence of heterogeneous organic compounds, could be useful as preliminary support tools for the identification and prioritization of new potential POPs among already existing chemicals as well as "screening prior to synthesis" procedures to avoid the production, and consequent release into the environment, of new POPs.

  9. Persistence and extinction of an n-species mutualism model with random perturbations in a polluted environment

    Science.gov (United States)

    He, Xin; Shan, Meijing; Liu, Meng

    2018-02-01

    An n-species stochastic Lotka-Volterra cooperative model in a polluted environment is proposed and studied. For each species, sufficient conditions for extinction, non-persistence in the mean and weak persistence in the mean are established. The threshold between weak persistence in the mean and extinction is obtained. Several numerical figures are also worked out to validate the theoretical results.

  10. Column Testing and 1D Reactive Transport Modeling to Evaluate Uranium Plume Persistence Processes

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Raymond H. [Navarro Research and Engineering, Inc.; Morrison, Stan [Navarro Research and Engineering, Inc.; Morris, Sarah [Navarro Research and Engineering, Inc.; Tigar, Aaron [Navarro Research and Engineering, Inc.; Dam, William [U.S. Department of Energy, Office of Legacy Management; Dayvault, Jalena [U.S. Department of Energy, Office of Legacy Management

    2016-04-26

    Motivation for Study: Natural flushing of contaminants at various U.S. Department of Energy Office of Legacy Management sites is not proceeding as quickly as predicted (plume persistence) Objectives: Help determine natural flushing rates using column tests. Use 1D reactive transport modeling to better understand the major processes that are creating plume persistence Approach: Core samples from under a former mill tailings area Tailings have been removed. Column leaching using lab-prepared water similar to nearby Gunnison River water. 1D reactive transport modeling to evaluate processes

  11. Modeling the Mechanisms by Which HIV-Associated Immunosuppression Influences HPV Persistence at the Oral Mucosa.

    Science.gov (United States)

    Verma, Meghna; Erwin, Samantha; Abedi, Vida; Hontecillas, Raquel; Hoops, Stefan; Leber, Andrew; Bassaganya-Riera, Josep; Ciupe, Stanca M

    2017-01-01

    Human immunodeficiency virus (HIV)-infected patients are at an increased risk of co-infection with human papilloma virus (HPV), and subsequent malignancies such as oral cancer. To determine the role of HIV-associated immune suppression on HPV persistence and pathogenesis, and to investigate the mechanisms underlying the modulation of HPV infection and oral cancer by HIV, we developed a mathematical model of HIV/HPV co-infection. Our model captures known immunological and molecular features such as impaired HPV-specific effector T helper 1 (Th1) cell responses, and enhanced HPV infection due to HIV. We used the model to determine HPV prognosis in the presence of HIV infection, and identified conditions under which HIV infection alters HPV persistence in the oral mucosa system. The model predicts that conditions leading to HPV persistence during HIV/HPV co-infection are the permissive immune environment created by HIV and molecular interactions between the two viruses. The model also determines when HPV infection continues to persist in the short run in a co-infected patient undergoing antiretroviral therapy. Lastly, the model predicts that, under efficacious antiretroviral treatment, HPV infections will decrease in the long run due to the restoration of CD4+ T cell numbers and protective immune responses.

  12. Models To Predict Persistent Scatterers Data Distribution And Their Capacity To Register Movement Along The Slope

    Science.gov (United States)

    Notti, D.; Meisina, C.; Zucca, F.; Colombo, A.

    2012-01-01

    Two models were developed to improve the use of persistent scatterers (PS) techniques in the landslides studies. The first model, called “CR-Index”, allows to forecast the potential PS distribution calculating the effect of topography and of the land use. The second model, called “V slope Coefficient”, has the aim to calculate the percentage of the movement detected along Vlos supposing to have a slide parallel to the maximum slope line.

  13. Persistence as a System-Functional Personality Trait and the Five-Factor Model

    Directory of Open Access Journals (Sweden)

    A A Vorobyeva

    2014-12-01

    Full Text Available The article addresses the results of the correlation analysis and joint factor analysis conducted to find correlations and links between persistence as a personal trait as seen in the system-functional approach developed by Alexander I. Krupnov and the traits of the Big Five model of personality.

  14. Measuring Short- and Long-run Promotional Effectiveness on Scanner Data Using Persistence Modeling

    NARCIS (Netherlands)

    M.G. Dekimpe (Marnik); D.M. Hanssens (Dominique); V.R. Nijs; J-B.E.M. Steenkamp (Jan-Benedict)

    2003-01-01

    textabstractThe use of price promotions to stimulate brand and firm performance is increasing. We discuss how (i) the availability of longer scanner data time series, and (ii) persistence modeling, have lead to greater insights into the dynamic effects of price promotions, as one can now quantify

  15. The Relations between Implicit Intelligence Beliefs, Autonomous Academic Motivation, and School Persistence Intentions: A Mediation Model

    Science.gov (United States)

    Renaud-Dubé, Andréanne; Guay, Frédéric; Talbot, Denis; Taylor, Geneviève; Koestner, Richard

    2015-01-01

    This study attempts to test a model in which the relation between implicit theories of intelligence and students' school persistence intentions are mediated by intrinsic, identified, introjected, and external regulations. Six hundred and fifty students from a high school were surveyed. Contrary to expectations, results from ESEM analyses indicated…

  16. The dual pathway to creativity model : Creative ideation as a function of flexibility and persistence

    NARCIS (Netherlands)

    Nijstad, B.A.; De Dreu, C.K.W.; Rietzschel, E.F.; Baas, M.

    2010-01-01

    The dual pathway to creativity model argues that creativity-the generation of original and appropriate ideas-is a function of cognitive flexibility and cognitive persistence, and that dispositional or situational variables may influence creativity either through their effects on flexibility, on

  17. The Federal Transformation Intervention Model in Persistently Lowest Achieving High Schools: A Mixed-Methods Study

    Science.gov (United States)

    Le Patner, Michelle B.

    2012-01-01

    This study examined the American Recovery and Reinvestment Act federal mandate of the Transformation Intervention Model (TIM) outlined by the School Improvement Grant, which was designed to turn around persistently lowest achieving schools. The study was conducted in four high schools in a large Southern California urban district that selected the…

  18. Clinical Prediction Model and Tool for Assessing Risk of Persistent Pain After Breast Cancer Surgery

    DEFF Research Database (Denmark)

    Meretoja, Tuomo J; Andersen, Kenneth Geving; Bruce, Julie

    2017-01-01

    are missing. The aim was to develop a clinically applicable risk prediction tool. Methods The prediction models were developed and tested using three prospective data sets from Finland (n = 860), Denmark (n = 453), and Scotland (n = 231). Prediction models for persistent pain of moderate to severe intensity......), high body mass index ( P = .039), axillary lymph node dissection ( P = .008), and more severe acute postoperative pain intensity at the seventh postoperative day ( P = .003) predicted persistent pain in the final prediction model, which performed well in the Danish (ROC-AUC, 0.739) and Scottish (ROC......-AUC, 0.740) cohorts. At the 20% risk level, the model had 32.8% and 47.4% sensitivity and 94.4% and 82.4% specificity in the Danish and Scottish cohorts, respectively. Conclusion Our validated prediction models and an online risk calculator provide clinicians and researchers with a simple tool to screen...

  19. A Model for Predicting Persistent Elevation of Factor VIII among Patients with Acute Ischemic Stroke

    Science.gov (United States)

    Samai, Alyana A.; Boehme, Amelia K.; Shaban, Amir; George, Alexander J.; Dowell, Lauren; Monlezun, Dominique J.; Leissinger, Cindy; Schluter, Laurie; El Khoury, Ramy; Martin-Schild, Sheryl

    2016-01-01

    Background and Purpose Elevated levels of coagulation factor VIII (FVIII) may persist independent of the acute-phase response; however, this relationship has not been investigated relative to acute ischemic stroke (AIS). We examined the frequency and predictors of persistently elevated FVIII in AIS patients. Methods AIS patients admitted between July 2008 and May 2014 with elevated baseline FVIII levels and repeat FVIII levels drawn for more than 7 days postdischarge were included. The patients were dichotomized by repeat FVIII level for univariate analysis at 150% and 200% activity thresholds. An adjusted model was developed to predict the likelihood of persistently elevated FVIII levels. Results Among 1616 AIS cases, 98 patients with elevated baseline FVIII had repeat FVIII levels. Persistent FVIII elevation was found in more than 75% of patients. At the 150% threshold, the prediction score ranged from 0 to 7 and included black race, female sex, prior stroke, hyperlipidemia, smoking, baseline FVIII > 200%, and baseline von Willebrand factor (vWF) level greater than 200%. At the 200% threshold, the prediction score ranged from 0–5 and included female sex, prior stroke, diabetes mellitus, baseline FVIII level greater 200%, and baseline vWF level greater than 200%. For each 1-point increase in score, the odds of persistent FVIII at both the 150% threshold (odds ratio [OR] = 10.4, 95% confidence interval [CI] 1.63–66.9, P = .0134) and 200% threshold (OR = 10.2, 95% CI 1.82–57.5, P = .0083) increased 10 times. Conclusion Because an elevated FVIII level confers increased stroke risk, our model for anticipating a persistently elevated FVIII level may identify patients at high risk for recurrent stroke. FVIII may be a target for secondary stroke prevention. PMID:26777556

  20. Stochastic extinction and persistence of a parasite-host epidemiological model

    Science.gov (United States)

    Liu, Yuting; Shan, Meijing; Lian, Xinze; Wang, Weiming

    2016-11-01

    In this paper, we investigate the stochastic extinction and persistence of a parasite-host epidemiological model. We show that the global dynamics of the stochastic model can be governed by the basic reproduction number R0S : if R0S 1, under mild extra conditions, the disease persists and endemic dynamics occurs almost surely, the solutions of the stochastic model fluctuate around the steady state of the deterministic model, and a unique stationary distribution can be found. Based on realistic parameters of Daphnia-microparasite system, numerical simulations have been performed to verify/extend our analytical results. Epidemiologically, we find that: (1) Large environment fluctuations can suppress the outbreak of disease; (2) The distributions are governed by R0S ; (3) The noise perturbations can be beneficial to control the spread of disease on average.

  1. Estimating overall persistence and long-range transport potential of persistent organic pollutants: a comparison of seven multimedia mass balance models and atmospheric transport models.

    Science.gov (United States)

    Hollander, A; Scheringer, M; Shatalov, V; Mantseva, E; Sweetman, A; Roemer, M; Baart, A; Suzuki, N; Wegmann, F; van de Meent, D

    2008-10-01

    Two different approaches to modeling the environmental fate of organic chemicals have been developed in recent years. The first approach is applied in multimedia box models, calculating average concentrations in homogeneous boxes which represent the different environmental media, based on intermedia partitioning, transport, and degradation processes. In the second approach, used in atmospheric transport models, the spatially and temporally variable atmospheric dynamics form the basis for calculating the environmental distribution of chemicals, from which also exchange processes to other environmental media are modeled. The main goal of the present study was to investigate if the multimedia mass balance models CliMoChem, SimpleBox, EVn-BETR, G-CIEMS, OECD Tool and the atmospheric transport models MSCE-POP and ADEPT predict the same rankings of the overall persistence (P(ov)) and long-range transport potential (LRTP) of POPs, and to explain differences and similarities between the rankings by the mass distributions and inter-compartment mass flows. The study was performed for a group of 14 reference chemicals. For P(ov), the models yield consistent results, owing to the large influence of phase partitioning parameters and degradation rate constants, which are used similarly by all models. Concerning LRTP, there are larger differences between the models than for P(ov), due to different LRTP calculation methods and spatial model resolutions. Between atmospheric transport models and multimedia fate models, no large differences in mass distributions and inter-compartment flows can be recognized. Deviations in mass flows are mainly caused by the geometrical design of the models.

  2. Stochastic persistence and stationary distribution in an SIS epidemic model with media coverage

    Science.gov (United States)

    Guo, Wenjuan; Cai, Yongli; Zhang, Qimin; Wang, Weiming

    2018-02-01

    This paper aims to study an SIS epidemic model with media coverage from a general deterministic model to a stochastic differential equation with environment fluctuation. Mathematically, we use the Markov semigroup theory to prove that the basic reproduction number R0s can be used to control the dynamics of stochastic system. Epidemiologically, we show that environment fluctuation can inhibit the occurrence of the disease, namely, in the case of disease persistence for the deterministic model, the disease still dies out with probability one for the stochastic model. So to a great extent the stochastic perturbation under media coverage affects the outbreak of the disease.

  3. Metapopulation modelling of riparian tree species persistence in river networks under climate change.

    Science.gov (United States)

    Van Looy, Kris; Piffady, Jérémy

    2017-11-01

    Floodplain landscapes are highly fragmented by river regulation resulting in habitat degradation and flood regime perturbation, posing risks to population persistence. Climate change is expected to pose supplementary risks in this context of fragmented landscapes, and especially for river systems adaptation management programs are developed. The association of habitat quality and quantity with the landscape dynamics and resilience to human-induced disturbances is still poorly understood in the context of species survival and colonization processes, but essential to prioritize conservation and restoration actions. We present a modelling approach that elucidates network connectivity and landscape dynamics in spatial and temporal context to identify vital corridors and conservation priorities in the Loire river and its tributaries. Alteration of flooding and flow regimes is believed to be critical to population dynamics in river ecosystems. Still, little is known of critical levels of alteration both spatially and temporally. We applied metapopulation modelling approaches for a dispersal-limited tree species, white elm; and a recruitment-limited tree species, black poplar. In different model steps the connectivity and natural dynamics of the river landscape are confronted with physical alterations (dams/dykes) to species survival and then future scenarios for climatic changes and potential adaptation measures are entered in the model and translated in population persistence over the river basin. For the two tree species we highlighted crucial network zones in relation to habitat quality and connectivity. Where the human impact model already shows currently restricted metapopulation development, climate change is projected to aggravate this persistence perspective substantially. For both species a significant drawback to the basin population is observed, with 1/3 for elm and ¼ for poplar after 25 years already. But proposed adaptation measures prove effective to even

  4. Modelling the HIV persistence through the network of lymphocyte recirculation in vivo

    Directory of Open Access Journals (Sweden)

    Ying Huang

    2017-02-01

    Full Text Available Human Immunodeficiency Virus (HIV is able to persist in cellular and/or anatomical viral reservoirs, despite the effective inhibition of virus replication by the antiretroviral therapy (ART. Here we develop a mathematical model to gain some insights of HIV persistence relevant to the lymphocyte recirculation network of immune system and the central nervous system (CNS. Our simulations and analyses illustrate the role of the CNS as a virus reservoir to prevent antiretroviral drugs from penetrating the blood-brain (or blood-testis barrier, and we examine the long-term impact of this reservoir on the transmissibility of an infected individual. We observe numerically that level of HIV in peripheral blood may not accurately reflect the true mechanisms occurring within other organs. Keywords: HIV reservoirs, Blood-brain barrier, Dynamical model, Lymphocyte recirculation network, 2010 MSC: 39A11, 92D30

  5. Modeling the Effect of Traffic Calming on Local Animal Population Persistence

    Directory of Open Access Journals (Sweden)

    Frank van Langevelde

    2009-12-01

    Full Text Available A steady growth in traffic volumes in industrialized countries with dense human populations is expected, especially on minor roads. As a consequence, the fragmentation of wildlife populations will increase dramatically. In human-dominated landscapes, typically minor roads occur in high densities, and animals encounter them frequently. Traffic calming is a new approach to mitigate negative impacts by reducing traffic volumes and speeds on minor roads at a regional scale. This leads to a distinction between roads with low volumes as being part of the traffic-calmed area, whereas roads with bundled traffic are located around this area. Within the traffic-calmed area, volumes and speeds can be decreased substantially; this is predicted to decrease the disturbance and mortality risk for animals. Thus far, data on the effects of traffic calming on wildlife population persistence remain scarce. Using metapopulation theory, we derived a model to estimate thresholds in the size of traffic-calmed areas and traffic volumes that may allow persistent populations. Our model suggests that traffic calming largely increases the persistence of roe deer in a landscape with a dense road network. Our modeling results show trade-offs between traffic volume on roads within the traffic-calmed area and both the area of habitat available for this species in the traffic-calmed area and the size of the traffic-calmed area. These results suggest ways to mitigate the fragmentation of wildlife habitat by road networks and their expected traffic volumes.

  6. The lure of rationality: Why does the deficit model persist in science communication?

    Science.gov (United States)

    Simis, Molly J; Madden, Haley; Cacciatore, Michael A; Yeo, Sara K

    2016-05-01

    Science communication has been historically predicated on the knowledge deficit model. Yet, empirical research has shown that public communication of science is more complex than what the knowledge deficit model suggests. In this essay, we pose four lines of reasoning and present empirical data for why we believe the deficit model still persists in public communication of science. First, we posit that scientists' training results in the belief that public audiences can and do process information in a rational manner. Second, the persistence of this model may be a product of current institutional structures. Many graduate education programs in science, technology, engineering, and math (STEM) fields generally lack formal training in public communication. We offer empirical evidence that demonstrates that scientists who have less positive attitudes toward the social sciences are more likely to adhere to the knowledge deficit model of science communication. Third, we present empirical evidence of how scientists conceptualize "the public" and link this to attitudes toward the deficit model. We find that perceiving a knowledge deficit in the public is closely tied to scientists' perceptions of the individuals who comprise the public. Finally, we argue that the knowledge deficit model is perpetuated because it can easily influence public policy for science issues. We propose some ways to uproot the deficit model and move toward more effective science communication efforts, which include training scientists in communication methods grounded in social science research and using approaches that engage community members around scientific issues. © The Author(s) 2016.

  7. Diverse Secreted Effectors Are Required for Salmonella Persistence in a Mouse Infection Model

    Energy Technology Data Exchange (ETDEWEB)

    Kidwai, Afshan S.; Mushamiri, Ivy T.; Niemann, George; Brown, Roslyn N.; Adkins, Joshua N.; Heffron, Fred

    2013-08-12

    Salmonella enterica serovar Typhimurium causes typhoid-like disease in mice and is a model of typhoid fever in humans. One of the hallmarks of typhoid is persistence, the ability of the bacteria to survive in the host weeks after infection. Virulence factors called effectors facilitate this process by direct transfer to the cytoplasm of infected cells thereby subverting cellular processes. Secretion of effectors to the cell cytoplasm takes place through multiple routes, including two separate type III secretion (T3SS) apparati as well as outer membrane vesicles. The two T3SS are encoded on separate pathogenicity islands, SPI-1 and -2, with SPI-1 more strongly associated with the intestinal phase of infection, and SPI-2 with the systemic phase. Both T3SS are required for persistence, but the effectors required have not been systematically evaluated. In this study, mutations in 48 described effectors were tested for persistence. We replaced each effector with a specific DNA barcode sequence by allelic exchange and co-infected with a wild-type reference to calculate the ratio of wild-type parent to mutant at different times after infection. The competitive index (CI) was determined by quantitative PCR in which primers that correspond to the barcode were used for amplification. Mutations in all but seven effectors reduced persistence demonstrating that most effectors were required. One exception was CigR, a recently discovered effector that is widely conserved throughout enteric bacteria. Deletion of cigR increased lethality, suggesting that it may be an anti-virulence factor. The fact that almost all Salmonella effectors are required for persistence argues against redundant functions. This is different from effector repertoires in other intracellular pathogens such as Legionella.

  8. Diverse secreted effectors are required for Salmonella persistence in a mouse infection model.

    Directory of Open Access Journals (Sweden)

    Afshan S Kidwai

    Full Text Available Salmonella enterica serovar Typhimurium causes typhoid-like disease in mice and is a model of typhoid fever in humans. One of the hallmarks of typhoid is persistence, the ability of the bacteria to survive in the host weeks after infection. Virulence factors called effectors facilitate this process by direct transfer to the cytoplasm of infected cells thereby subverting cellular processes. Secretion of effectors to the cell cytoplasm takes place through multiple routes, including two separate type III secretion (T3SS apparati as well as outer membrane vesicles. The two T3SS are encoded on separate pathogenicity islands, SPI-1 and -2, with SPI-1 more strongly associated with the intestinal phase of infection, and SPI-2 with the systemic phase. Both T3SS are required for persistence, but the effectors required have not been systematically evaluated. In this study, mutations in 48 described effectors were tested for persistence. We replaced each effector with a specific DNA barcode sequence by allelic exchange and co-infected with a wild-type reference to calculate the ratio of wild-type parent to mutant at different times after infection. The competitive index (CI was determined by quantitative PCR in which primers that correspond to the barcode were used for amplification. Mutations in all but seven effectors reduced persistence demonstrating that most effectors were required. One exception was CigR, a recently discovered effector that is widely conserved throughout enteric bacteria. Deletion of cigR increased lethality, suggesting that it may be an anti-virulence factor. The fact that almost all Salmonella effectors are required for persistence argues against redundant functions. This is different from effector repertoires in other intracellular pathogens such as Legionella.

  9. Hepatitis B virus core antigen determines viral persistence in a C57BL/6 mouse model.

    Science.gov (United States)

    Lin, Yi-Jiun; Huang, Li-Rung; Yang, Hung-Chih; Tzeng, Horng-Tay; Hsu, Ping-Ning; Wu, Hui-Lin; Chen, Pei-Jer; Chen, Ding-Shinn

    2010-05-18

    We recently developed a mouse model of hepatitis B virus (HBV) persistence, in which a single i.v. hydrodynamic injection of HBV DNA to C57BL/6 mice allows HBV replication and induces a partial immune response, so that about 20-30% of the mice carry HBV for more than 6 months. The model was used to identify the viral antigen crucial for HBV persistence. We knocked out individual HBV genes by introducing a premature termination codon to the HBV core, HBeAg, HBx, and polymerase ORFs. The specific-gene-deficient HBV mutants were hydrodynamically injected into mice and the HBV profiles of the mice were monitored. About 90% of the mice that received the HBcAg-mutated HBV plasmid exhibited high levels of hepatitis B surface antigenemia and maintained HBsAg expression for more than 6 months after injection. To map the region of HBcAg essential for viral clearance, we constructed a set of serial HBcAg deletion mutants for hydrodynamic injection. We localized the essential region of HBcAg to the carboxyl terminus, specifically to the 10 terminal amino acids (HBcAg176-185). The majority of mice receiving this HBV mutant DNA did not elicit a proper HBcAg-specific IFN-gamma response and expressed HBV virions for 6 months. These results indicate that the immune response triggered in mice by HBcAg during exposure to HBV is important in determining HBV persistence.

  10. A review of Red Queen models for the persistence of obligate sexual reproduction.

    Science.gov (United States)

    Lively, Curtis M

    2010-01-01

    I present a historical review of coevolutionary models for the evolutionary persistence of sexual reproduction. The focus is on the fate of obligately sexual populations facing competition with one or more obligately asexual clones. An early simulation model by Hamilton (Hamilton WD. 1980. Sex versus non-sex versus parasite. Oikos. 35:282-290.) suggested that parasites could be an important force in selecting against asexual clones, leading to the persistence of sex. This result was consistent with a number of independent verbal models generated from 1975-1983. Conversely, the models by May and Anderson (May RM, Anderson RM. 1983. Epidemiology and genetics in the coevolution of parasites and hosts. Proc R Soc Lond B Biol Sci. 219:281-313.), which included more epidemiological detail, suggested that parasites were an unlikely source of selection to favor sexual over asexual reproduction. Thus began an oscillation of opinion regarding the role of parasites in selection for sex. It would seem at present that some of the differences of opinion over time stemmed from the different ways that models were constructed, including whether the sexual population was in competition with a genetically diverse asexual population or a single clonal genotype. On theoretical grounds, parasite-mediated selection for sex seems more likely if the sexual population has options in genotypic space that are not available to the clones. Models that incorporate more ecological realism also seem more favorable to the parasite theory of sex.

  11. Compartmental model for tritium persistence in the soil-plant system

    International Nuclear Information System (INIS)

    Iyengar, T.S.; Sadarangani, S.H.; Vaze, P.K.; Soman, S.D.

    1977-01-01

    A three-component computer model for tritium persistence in the soil-plant system, on the basis of an exponential polynomial is attempted. A series of field experiments with four species of trees, viz. Cardia sebastina, Terminalia catappa, Aracaria bidwilli and Mangifera indica, were carried out to generate data for testing the model. It is observed that there are two short-term components and one long-term component for tritium mean residence time, corresponding to the three phases of tritium in the system, viz. Tissue-Free-Water-Tritium, labile component of Tissue-Bound-Tritium and non-labile component of Tissue-Bound-Tritium. (author)

  12. Discrete-time semi-Markov modeling of human papillomavirus persistence

    Science.gov (United States)

    Mitchell, C. E.; Hudgens, M. G.; King, C. C.; Cu-Uvin, S.; Lo, Y.; Rompalo, A.; Sobel, J.; Smith, J. S.

    2011-01-01

    Multi-state modeling is often employed to describe the progression of a disease process. In epidemiological studies of certain diseases, the disease state is typically only observed at periodic clinical visits, producing incomplete longitudinal data. In this paper we consider fitting semi-Markov models to estimate the persistence of human papillomavirus (HPV) type-specific infection in studies where the status of HPV type(s) is assessed periodically. Simulation study results are presented indicating the semi-Markov estimator is more accurate than an estimator currently used in the HPV literature. The methods are illustrated using data from the HIV Epidemiology Research Study (HERS). PMID:21538985

  13. Neutrino masses, muon g-2, and lepton-flavour violation in the supersymmetric see-saw model

    CERN Document Server

    Hisano, J; Hisano, Junji; Tobe, Kazuhiro

    2001-01-01

    In the light of the recent muon (g_mu-2) result by the E821 experiment at the Brookhaven National Laboratory, we study the event rates of the charged lepton-flavour-violating (LFV) processes in the supersymmetric standard model (SUSY SM) with the heavy right-handed neutrinos (SUSY see-saw model). Since the left-handed sleptons get the LFV masses via the neutrino Yukawa interaction in this model, the event rate of mu->e gamma and the SUSY-SM correction to (g_mu-2)/2 (a_mu(SUSY)) are strongly correlated. When the left-handed sleptons have a LFV mass between the first and second generations ((m^2_L)_{12}) in the mass matrix, it should be suppressed by \\sim 10^{-3} (10^{-9}/a_mu(SUSY)) compared with the diagonal components (m_SUSY^2), from the current experimental bound on mu->e gamma. The recent (g_mu-2) result indicates a_mu(SUSY) \\sim 10^{-9}. The future charged LFV experiments could cover (m^2_L)_{12}/m_SUSY^2 \\gsim 10^{-(5-6)}. These experiments will give a significant impact on the flavour models and the SU...

  14. Chemostat modeling of Escherichia coli persistence in conventionalized mono-associated and streptomycin-treated mice.

    Science.gov (United States)

    Rang, C; Midtvedt, T; Molin, S; Chao, L

    2001-01-01

    We have previously shown that Escherichia coli BJ4 has similar doubling time in mice that are mono-associated (having only the inoculated E. coli BJ4) or streptomycin-treated (having mainly gram-positive bacteria plus the inoculated E. coli BJ4). We also showed that when the mice were conventionalized (fed cecum homogenate from conventional mice or ones with a complete microbial flora), the introduction of complete flora in both cases increased the in vivo doubling time, while decreasing the colony counts in fecal samples. To determine whether the increase in doubling time could explain the decrease in colony counts, we analyzed our previous results by a chemostat model. The analysis shows that the increasing doubling time alone is sufficient to explain the decrease in colony counts in mono-associated mice, but not in the streptomycin-treated mice. The observed decreasing rate in colony counts in streptomycin-treated mice is slower than predicted. Furthermore, whereas the model predicted a decrease to extinction in both mice, the E. coli persist at a frequency 10-80 times higher in streptomycin-treated mice than in mono-associated mice. Thus, while a chemostat model is able to explain some of the population dynamics of intestinal bacteria in mice, additional factors not included in the model are stabilizing the system. Because we find that E. coli declines more slowly and to a higher stabilization frequency in streptomycin-treated mice, which have a more diverse flora before conventionalization, we take these results to suggest that the persistence of E. coli populations is promoted by species diversity. We propose that a mechanism for the persistence may be the presence of new E. coli niches created by keystone species in the more diverse flora.

  15. Numerical Modeling of Persistent Winter Fog over the Indo-Gangetic Plains

    Science.gov (United States)

    Ghimire, S.; Adhikary, B.; Praveen, P. S.; Panday, A. K.

    2017-12-01

    Every winter the Indo-Gangetic Plains (IGP) in northern South Asia; bounded by the great Himalayas in the north, are periodically covered by dense and persistent fog that severely impacts day-to-day activities of several hundred million people. The fog can stretch over several hundred kilometers and last several days in many locations. Despite the fog's high impact, there are very limited in-situ observations available to characterize persistent fog episodes. Also, there has been very little success to date in accurately predicting the fog occurrence and extent over a larger area such as IGP. This study will present insights into the performance of the Weather Research and Forecasting (WRF) model simulating persistent winter fog prediction in the IGP region, compared to satellite observations and in-situ measurements. Since fog is not a prognostic variable in WRF, the study presents results based on multi-rule diagnostic algorithms published in peer reviewed journals. In addition, fog episodes were analyzed using the Air Force Weather Agency (AFWA) diagnostics package available for WRF. On a regional scale, MODIS data onboard the TERRA and AQUA satellites are used to evaluate model performance skills. At a local scale, the model is evaluated at two sites in the southern Nepal, Lumbini and Chitwan, located in the IGP. Lumbini and Chitwan observatories have Luftt and Biral weather sensors which allow monitoring presence of fog, visibility range and surface meteorology. In addition, for Chitwan, data from DMT Fog Monitor (FM 120) and Luftt CHM 15K Ceilometer were used to compare model performance for liquid-water content and planetary boundary layer during foggy and non-foggy days.

  16. Increasing persistence in undergraduate science majors: a model for institutional support of underrepresented students.

    Science.gov (United States)

    Toven-Lindsey, Brit; Levis-Fitzgerald, Marc; Barber, Paul H; Hasson, Tama

    2015-01-01

    The 6-yr degree-completion rate of undergraduate science, technology, engineering, and mathematics (STEM) majors at U.S. colleges and universities is less than 40%. Persistence among women and underrepresented minorities (URMs), including African-American, Latino/a, Native American, and Pacific Islander students, is even more troubling, as these students leave STEM majors at significantly higher rates than their non-URM peers. This study utilizes a matched comparison group design to examine the academic achievement and persistence of students enrolled in the Program for Excellence in Education and Research in the Sciences (PEERS), an academic support program at the University of California, Los Angeles, for first- and second-year science majors from underrepresented backgrounds. Results indicate that PEERS students, on average, earned higher grades in most "gatekeeper" chemistry and math courses, had a higher cumulative grade point average, completed more science courses, and persisted in a science major at significantly higher rates than the comparison group. With its holistic approach focused on academics, counseling, creating a supportive community, and exposure to research, the PEERS program serves as an excellent model for universities interested in and committed to improving persistence of underrepresented science majors and closing the achievement gap. © 2015 B. Toven-Lindsey et al. CBE—Life Sciences Education © 2015 The American Society for Cell Biology. This article is distributed by The American Society for Cell Biology under license from the author(s). It is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License (http://creativecommons.org/licenses/by-nc-sa/3.0).

  17. Column Testing and 1D Reactive Transport Modeling to Evaluate Uranium Plume Persistence Processes

    Science.gov (United States)

    Johnson, R. H.; Morrison, S.; Morris, S.; Tigar, A.; Dam, W. L.; Dayvault, J.

    2015-12-01

    At many U.S. Department of Energy Office of Legacy Management sites, 100 year natural flushing was selected as a remedial option for groundwater uranium plumes. However, current data indicate that natural flushing is not occurring as quickly as expected and solid-phase and aqueous uranium concentrations are persistent. At the Grand Junction, Colorado office site, column testing was completed on core collected below an area where uranium mill tailings have been removed. The total uranium concentration in this core was 13.2 mg/kg and the column was flushed with laboratory-created water with no uranium and chemistry similar to the nearby Gunnison River. The core was flushed for a total of 91 pore volumes producing a maximum effluent uranium concentration of 6,110 μg/L at 2.1 pore volumes and a minimum uranium concentration of 36.2 μg/L at the final pore volume. These results indicate complex geochemical reactions at small pore volumes and a long tailing affect at greater pore volumes. Stop flow data indicate the occurrence of non-equilibrium processes that create uranium concentration rebound. These data confirm the potential for plume persistence, which is occurring at the field scale. 1D reactive transport modeling was completed using PHREEQC (geochemical model) and calibrated to the column test data manually and using PEST (inverse modeling calibration routine). Processes of sorption, dual porosity with diffusion, mineral dissolution, dispersion, and cation exchange were evaluated separately and in combination. The calibration results indicate that sorption and dual porosity are major processes in explaining the column test data. These processes are also supported by fission track photographs that show solid-phase uranium residing in less mobile pore spaces. These procedures provide valuable information on plume persistence and secondary source processes that may be used to better inform and evaluate remedial strategies, including natural flushing.

  18. Prediction of persistent hemodynamic depression after carotid angioplasty and stenting using artificial neural network model.

    Science.gov (United States)

    Jeon, Jin Pyeong; Kim, Chulho; Oh, Byoung-Doo; Kim, Sun Jeong; Kim, Yu-Seop

    2018-01-01

    To assess and compare predictive factors for persistent hemodynamic depression (PHD) after carotid artery angioplasty and stenting (CAS) using artificial neural network (ANN) and multiple logistic regression (MLR) or support vector machines (SVM) models. A retrospective data set of patients (n=76) who underwent CAS from 2007 to 2014 was used as input (training cohort) to a back-propagation ANN using TensorFlow platform. PHD was defined when systolic blood pressure was less than 90mmHg or heart rate was less 50 beats/min that lasted for more than one hour. The resulting ANN was prospectively tested in 33 patients (test cohort) and compared with MLR or SVM models according to accuracy and receiver operating characteristics (ROC) curve analysis. No significant difference in baseline characteristics between the training cohort and the test cohort was observed. PHD was observed in 21 (27.6%) patients in the training cohort and 10 (30.3%) patients in the test cohort. In the training cohort, the accuracy of ANN for the prediction of PHD was 98.7% and the area under the ROC curve (AUROC) was 0.961. In the test cohort, the number of correctly classified instances was 32 (97.0%) using the ANN model. In contrast, the accuracy rate of MLR or SVM model was both 75.8%. ANN (AUROC: 0.950; 95% CI [confidence interval]: 0.813-0.996) showed superior predictive performance compared to MLR model (AUROC: 0.796; 95% CI: 0.620-0.915, p<0.001) or SVM model (AUROC: 0.885; 95% CI: 0.725-0.969, p<0.001). The ANN model seems to have more powerful prediction capabilities than MLR or SVM model for persistent hemodynamic depression after CAS. External validation with a large cohort is needed to confirm our results. Copyright © 2017. Published by Elsevier B.V.

  19. Genetic Parameters for Milk Yield and Lactation Persistency Using Random Regression Models in Girolando Cattle

    OpenAIRE

    Canaza-Cayo, Ali William; Lopes, Paulo Sávio; da Silva, Marcos Vinicius Gualberto Barbosa; de Almeida Torres, Robledo; Martins, Marta Fonseca; Arbex, Wagner Antonio; Cobuci, Jaime Araujo

    2015-01-01

    A total of 32,817 test-day milk yield (TDMY) records of the first lactation of 4,056 Girolando cows daughters of 276 sires, collected from 118 herds between 2000 and 2011 were utilized to estimate the genetic parameters for TDMY via random regression models (RRM) using Legendre’s polynomial functions whose orders varied from 3 to 5. In addition, nine measures of persistency in milk yield (PSi) and the genetic trend of 305-day milk yield (305MY) were evaluated. The fit quality criteria used in...

  20. Genetic Parameters for Milk Yield and Lactation Persistency Using Random Regression Models in Girolando Cattle.

    Science.gov (United States)

    Canaza-Cayo, Ali William; Lopes, Paulo Sávio; da Silva, Marcos Vinicius Gualberto Barbosa; de Almeida Torres, Robledo; Martins, Marta Fonseca; Arbex, Wagner Antonio; Cobuci, Jaime Araujo

    2015-10-01

    A total of 32,817 test-day milk yield (TDMY) records of the first lactation of 4,056 Girolando cows daughters of 276 sires, collected from 118 herds between 2000 and 2011 were utilized to estimate the genetic parameters for TDMY via random regression models (RRM) using Legendre's polynomial functions whose orders varied from 3 to 5. In addition, nine measures of persistency in milk yield (PSi) and the genetic trend of 305-day milk yield (305MY) were evaluated. The fit quality criteria used indicated RRM employing the Legendre's polynomial of orders 3 and 5 for fitting the genetic additive and permanent environment effects, respectively, as the best model. The heritability and genetic correlation for TDMY throughout the lactation, obtained with the best model, varied from 0.18 to 0.23 and from -0.03 to 1.00, respectively. The heritability and genetic correlation for persistency and 305MY varied from 0.10 to 0.33 and from -0.98 to 1.00, respectively. The use of PS7 would be the most suitable option for the evaluation of Girolando cattle. The estimated breeding values for 305MY of sires and cows showed significant and positive genetic trends. Thus, the use of selection indices would be indicated in the genetic evaluation of Girolando cattle for both traits.

  1. Genetic Parameters for Milk Yield and Lactation Persistency Using Random Regression Models in Girolando Cattle

    Directory of Open Access Journals (Sweden)

    Ali William Canaza-Cayo

    2015-10-01

    Full Text Available A total of 32,817 test-day milk yield (TDMY records of the first lactation of 4,056 Girolando cows daughters of 276 sires, collected from 118 herds between 2000 and 2011 were utilized to estimate the genetic parameters for TDMY via random regression models (RRM using Legendre’s polynomial functions whose orders varied from 3 to 5. In addition, nine measures of persistency in milk yield (PSi and the genetic trend of 305-day milk yield (305MY were evaluated. The fit quality criteria used indicated RRM employing the Legendre’s polynomial of orders 3 and 5 for fitting the genetic additive and permanent environment effects, respectively, as the best model. The heritability and genetic correlation for TDMY throughout the lactation, obtained with the best model, varied from 0.18 to 0.23 and from −0.03 to 1.00, respectively. The heritability and genetic correlation for persistency and 305MY varied from 0.10 to 0.33 and from −0.98 to 1.00, respectively. The use of PS7 would be the most suitable option for the evaluation of Girolando cattle. The estimated breeding values for 305MY of sires and cows showed significant and positive genetic trends. Thus, the use of selection indices would be indicated in the genetic evaluation of Girolando cattle for both traits.

  2. Recognition, survival and persistence of Staphylococcus aureus in the model host Tenebrio molitor.

    Science.gov (United States)

    Dorling, Jack; Moraes, Caroline; Rolff, Jens

    2015-02-01

    The degree of specificity of any given immune response to a parasite is governed by the complexity and variation of interactions between host and pathogen derived molecules. Here, we assess the extent to which recognition and immuno-resistance of cell wall mutants of the pathogen Staphylococcus aureus may contribute to establishment and maintenance of persistent infection in the model insect host, Tenebrio molitor. The cell surface of S. aureus is decorated with various molecules, including glycopolymers such as wall teichoic acid (WTA). WTA is covalently bound to peptidoglycan (PGN) and its absence has been associated with increased recognition of PGN by host receptors (PGRPs). WTA is also further modified by other molecules such as D-alanine (D-alanylation). Both the level of WTA expression and its D-alanylation were found to be important in the mediation of the host-parasite interaction in this model system. Specifically, WTA itself was seen to influence immune recognition, while D-alanylation of WTA was found to increase immuno-resistance and was associated with prolonged persistence of S. aureus in T. molitor. These results implicate WTA and its D-alanylation as important factors in the establishment and maintenance of persistent infection, affecting different critical junctions in the immune response; through potential evasion of recognition by PGRPs and resistance to humoral immune effectors during prolonged exposure to the immune system. This highlights a mechanism by which specificity in this host-parasite interaction may arise. Copyright © 2014 Elsevier Ltd. All rights reserved.

  3. A Murine Model of Persistent Inflammation, Immune Suppression, and Catabolism Syndrome

    Directory of Open Access Journals (Sweden)

    Amanda M. Pugh

    2017-08-01

    Full Text Available Critically ill patients that survive sepsis can develop a Persistent Inflammation, Immunosuppression, and Catabolism Syndrome (PICS, which often leads to extended recovery periods and multiple complications. Here, we utilized a cecal ligation and puncture (CLP method in mice with the goal of creating a model that concurrently displays all the characteristics of PICS. We observed that, after eight days, mice that survive the CLP develop persistent inflammation with significant myelopoiesis in the bone marrow and spleen. These mice also demonstrate ongoing immune suppression, as evidenced by the decreased total and naïve splenic CD4 and CD8 T cells with a concomitant increase in immature myeloid cells. The mice further display significant weight loss and decreased muscle mass, indicating a state of ongoing catabolism. When PICS mice are challenged with intranasal Pseudomonas aeruginosa, mortality is significantly elevated compared to sham mice. This mortality difference is associated with increased bacterial loads in the lung, as well as impaired neutrophil migration and neutrophil dysfunction in the PICS mice. Altogether, we have created a sepsis model that concurrently exhibits PICS characteristics. We postulate that this will help determine the mechanisms underlying PICS and identify potential therapeutic targets to improve outcomes for this patient population.

  4. Habit persistence

    DEFF Research Database (Denmark)

    Vinther Møller, Stig

    2009-01-01

    This paper uses an iterated GMM approach to estimate and test the consumption based habit persistence model of Campbell and Cochrane (1999) on the US stock market. The empirical evidence shows that the model is able to explain the size premium, but fails to explain the value premium. Further......, the state variable of the model - the surplus consumption ratio - explains counter-cyclical time-varying expected returns on stocks. The model also produces plausible low real risk-free rates despite high relative risk aversion....

  5. Validation of Finite-Element Models of Persistent-Current Effects in Nb3Sn Accelerator Magnets

    International Nuclear Information System (INIS)

    Wang, X.; Ambrosio, G.; Chlachidze, G.; Collings, E. W.; Dietderich, D. R.; DiMarco, J.; Felice, H.; Ghosh, A. K.; Godeke, A.; Gourlay, S. A.; Marchevsky, M.; Prestemon, S. O.; Sabbi, G.; Sumption, M. D.; Velev, G. V.; Xu, X.; Zlobin, A. V.

    2015-01-01

    Persistent magnetization currents are induced in superconducting filaments during the current ramping in magnets. The resulting perturbation to the design magnetic field leads to field quality degradation, in particular at low field where the effect is stronger relative to the main field. The effects observed in NbTi accelerator magnets were reproduced well with the critical-state model. However, this approach becomes less accurate for the calculation of the persistent-current effects observed in Nb 3 Sn accelerator magnets. Here a finite-element method based on the measured strand magnetization is validated against three state-of-art Nb3Sn accelerator magnets featuring different subelement diameters, critical currents, magnet designs and measurement temperatures. The temperature dependence of the persistent-current effects is reproduced. Based on the validated model, the impact of conductor design on the persistent current effects is discussed. The performance, limitations and possible improvements of the approach are also discussed

  6. Semi-global persistence and stability for a class of forced discrete-time population models

    Science.gov (United States)

    Franco, Daniel; Guiver, Chris; Logemann, Hartmut; Perán, Juan

    2017-12-01

    We consider persistence and stability properties for a class of forced discrete-time difference equations with three defining properties: the solution is constrained to evolve in the non-negative orthant, the forcing acts multiplicatively, and the dynamics are described by so-called Lur'e systems, containing both linear and non-linear terms. Many discrete-time biological models encountered in the literature may be expressed in the form of a Lur'e system and, in this context, the multiplicative forcing may correspond to harvesting, culling or time-varying (such as seasonal) vital rates or environmental conditions. Drawing upon techniques from systems and control theory, and assuming that the forcing is bounded, we provide conditions under which persistence occurs and, further, that a unique non-zero equilibrium is stable with respect to the forcing in a sense which is reminiscent of input-to-state stability, a concept well-known in nonlinear control theory. The theoretical results are illustrated with several examples. In particular, we discuss how our results relate to previous literature on stabilization of chaotic systems by so-called proportional feedback control.

  7. Repeated hapten exposure induces persistent tactile sensitivity in mice modeling localized provoked vulvodynia.

    Directory of Open Access Journals (Sweden)

    Jasmine Landry

    Full Text Available Vulvodynia is a remarkably prevalent chronic pain condition of unknown etiology. Epidemiologic studies associate the risk of vulvodynia with a history of atopic disease. We used an established model of hapten-driven contact hypersensitivity to investigate the underlying mechanisms of allergy-provoked prolonged sensitivity to pressure.We sensitized female ND4 Swiss mice to the hapten oxazolone on their flanks, and subsequently challenged them four days later with oxazolone or vehicle for ten consecutive days on the labia. We evaluated labiar sensitivity to touch, local mast cell accumulation, and hyperinnervation after ten challenges.Oxazolone-challenged mice developed significant tactile sensitivity that persisted for over three weeks after labiar allergen exposures ceased. Allergic sites were characterized by mast cell accumulation, sensory hyper-innervation and infiltration of regulatory CD4+CD25+FoxP3+ T cells as well as localized early increases in transcripts encoding Nerve Growth Factor and nerve-mast cell synapse marker Cell Adhesion Molecule 1. Local depletion of mast cells by intra-labiar administration of secretagogue compound 48/80 led to a reduction in both nerve density and tactile sensitivity.Mast cells regulate allergy-provoked persistent sensitivity to touch. Mast cell-targeted therapeutic strategies may provide novel means to manage and limit chronic pain conditions associated with atopic disease.

  8. Coronal hole evolution from multi-viewpoint data as input for a STEREO solar wind speed persistence model

    Directory of Open Access Journals (Sweden)

    Temmer Manuela

    2018-01-01

    Full Text Available We present a concept study of a solar wind forecasting method for Earth, based on persistence modeling from STEREO in situ measurements combined with multi-viewpoint EUV observational data. By comparing the fractional areas of coronal holes (CHs extracted from EUV data of STEREO and SoHO/SDO, we perform an uncertainty assessment derived from changes in the CHs and apply those changes to the predicted solar wind speed profile at 1 AU. We evaluate the method for the time period 2008–2012, and compare the results to a persistence model based on ACE in situ measurements and to the STEREO persistence model without implementing the information on CH evolution. Compared to an ACE based persistence model, the performance of the STEREO persistence model which takes into account the evolution of CHs, is able to increase the number of correctly predicted high-speed streams by about 12%, and to decrease the number of missed streams by about 23%, and the number of false alarms by about 19%. However, the added information on CH evolution is not able to deliver more accurate speed values for the forecast than using the STEREO persistence model without CH information which performs better than an ACE based persistence model. Investigating the CH evolution between STEREO and Earth view for varying separation angles over ∼25–140° East of Earth, we derive some relation between expanding CHs and increasing solar wind speed, but a less clear relation for decaying CHs and decreasing solar wind speed. This fact most likely prevents the method from making more precise forecasts. The obtained results support a future L5 mission and show the importance and valuable contribution using multi-viewpoint data.

  9. Coronal hole evolution from multi-viewpoint data as input for a STEREO solar wind speed persistence model

    Science.gov (United States)

    Temmer, Manuela; Hinterreiter, Jürgen; Reiss, Martin A.

    2018-03-01

    We present a concept study of a solar wind forecasting method for Earth, based on persistence modeling from STEREO in situ measurements combined with multi-viewpoint EUV observational data. By comparing the fractional areas of coronal holes (CHs) extracted from EUV data of STEREO and SoHO/SDO, we perform an uncertainty assessment derived from changes in the CHs and apply those changes to the predicted solar wind speed profile at 1 AU. We evaluate the method for the time period 2008-2012, and compare the results to a persistence model based on ACE in situ measurements and to the STEREO persistence model without implementing the information on CH evolution. Compared to an ACE based persistence model, the performance of the STEREO persistence model which takes into account the evolution of CHs, is able to increase the number of correctly predicted high-speed streams by about 12%, and to decrease the number of missed streams by about 23%, and the number of false alarms by about 19%. However, the added information on CH evolution is not able to deliver more accurate speed values for the forecast than using the STEREO persistence model without CH information which performs better than an ACE based persistence model. Investigating the CH evolution between STEREO and Earth view for varying separation angles over ˜25-140° East of Earth, we derive some relation between expanding CHs and increasing solar wind speed, but a less clear relation for decaying CHs and decreasing solar wind speed. This fact most likely prevents the method from making more precise forecasts. The obtained results support a future L5 mission and show the importance and valuable contribution using multi-viewpoint data.

  10. THE EFFECT OF RECIPROCAL TEACHING LEARNING MODEL INTEGRATED MIND MAP AND PERSISTENCE ON STUDENT RETENTION OF KINGDOM ANIMALIA CONCEPT

    OpenAIRE

    Septiana, Dwi; Miarsyah, Mieke; Komala, Ratna

    2017-01-01

    The low score of students learning outcome on Kingdom  Animalia concept indicate that there must an improvement of students retention. The aim of this study is to know the effect of reciprocal teaching learning model that integrated with mind map and persistence on students retention. The method that used in this research is quasi experiment with 2 x 2 factorial design. The instruments that used in this research are learning outcome test and persistence questionnaire. The subject of this...

  11. Modeling routes of chronic wasting disease transmission: Environmental prion persistence promotes deer population decline and extinction

    Science.gov (United States)

    Almberg, Emily S.; Cross, Paul C.; Johnson, Christopher J.; Heisey, Dennis M.; Richards, Bryan J.

    2011-01-01

    Chronic wasting disease (CWD) is a fatal disease of deer, elk, and moose transmitted through direct, animal-to-animal contact, and indirectly, via environmental contamination. Considerable attention has been paid to modeling direct transmission, but despite the fact that CWD prions can remain infectious in the environment for years, relatively little information exists about the potential effects of indirect transmission on CWD dynamics. In the present study, we use simulation models to demonstrate how indirect transmission and the duration of environmental prion persistence may affect epidemics of CWD and populations of North American deer. Existing data from Colorado, Wyoming, and Wisconsin's CWD epidemics were used to define plausible short-term outcomes and associated parameter spaces. Resulting long-term outcomes range from relatively low disease prevalence and limited host-population decline to host-population collapse and extinction. Our models suggest that disease prevalence and the severity of population decline is driven by the duration that prions remain infectious in the environment. Despite relatively low epidemic growth rates, the basic reproductive number, R0, may be much larger than expected under the direct-transmission paradigm because the infectious period can vastly exceed the host's life span. High prion persistence is expected to lead to an increasing environmental pool of prions during the early phases (i.e. approximately during the first 50 years) of the epidemic. As a consequence, over this period of time, disease dynamics will become more heavily influenced by indirect transmission, which may explain some of the observed regional differences in age and sex-specific disease patterns. This suggests management interventions, such as culling or vaccination, will become increasingly less effective as CWD epidemics progress.

  12. Modelling the bioaccumulation of persistent organic pollutants in agricultural food chains for regulatory exposure assessment.

    Science.gov (United States)

    Takaki, Koki; Wade, Andrew J; Collins, Chris D

    2017-02-01

    New models for estimating bioaccumulation of persistent organic pollutants in the agricultural food chain were developed using recent improvements to plant uptake and cattle transfer models. One model named AgriSim was based on K OW regressions of bioaccumulation in plants and cattle, while the other was a steady-state mechanistic model, AgriCom. The two developed models and European Union System for the Evaluation of Substances (EUSES), as a benchmark, were applied to four reported food chain (soil/air-grass-cow-milk) scenarios to evaluate the performance of each model simulation against the observed data. The four scenarios considered were as follows: (1) polluted soil and air, (2) polluted soil, (3) highly polluted soil surface and polluted subsurface and (4) polluted soil and air at different mountain elevations. AgriCom reproduced observed milk bioaccumulation well for all four scenarios, as did AgriSim for scenarios 1 and 2, but EUSES only did this for scenario 1. The main causes of the deviation for EUSES and AgriSim were the lack of the soil-air-plant pathway and the ambient air-plant pathway, respectively. Based on the results, it is recommended that soil-air-plant and ambient air-plant pathway should be calculated separately and the K OW regression of transfer factor to milk used in EUSES be avoided. AgriCom satisfied the recommendations that led to the low residual errors between the simulated and the observed bioaccumulation in agricultural food chain for the four scenarios considered. It is therefore recommended that this model should be incorporated into regulatory exposure assessment tools. The model uncertainty of the three models should be noted since the simulated concentration in milk from 5th to 95th percentile of the uncertainty analysis often varied over two orders of magnitude. Using a measured value of soil organic carbon content was effective to reduce this uncertainty by one order of magnitude.

  13. New mechanism for Type-II seesaw dominance in SO(10) with low-mass Z', RH neutrinos, and verifiable LFV, LNV and proton decay

    Energy Technology Data Exchange (ETDEWEB)

    Nayak, Bidyut Prava; Parida, Mina Ketan [Siksha ' ' O' ' Anusandhan University, Centre of Excellence in Theoretical and Mathematical Sciences, Bhubaneswar, Odisha (India)

    2015-05-15

    The dominance of Type-II seesaw mechanism for the neutrino masses has attracted considerable attention because of a number of advantages. We show a novel approach to achieve Type-II seesaw dominance in nonsupersymmetric SO(10) grand unification where a low-mass Z' boson and specific patterns of right-handed neutrino masses are predicted within the accessible energy range of the Large Hadron Collider. In spite of the high value of the seesaw scale, M{sub Δ{sub L}} ≅ 10{sup 8}-10{sup 9} GeV, the model predicts new dominant contributions to neutrino-less double beta decay in the W{sub L}-W{sub L} channel close to the current experimental limits via exchanges of heavier singlet fermions used as essential ingredients of this model even when the light active neutrino masses are normally hierarchical or invertedly hierarchical. We obtain upper bounds on the lightest sterile neutrino mass m{sub s} model applications including leptogenesis etc. are briefly indicated. (orig.)

  14. A probabilistic model for the persistence of early planar fabrics in polydeformed pelitic schists

    Science.gov (United States)

    Ferguson, C.C.

    1984-01-01

    Although early planar fabrics are commonly preserved within microlithons in low-grade pelites, in higher-grade (amphibolite facies) pelitic schists fabric regeneration often appears complete. Evidence for early fabrics may be preserved within porphyroblasts but, within the matrix, later deformation often appears to totally obliterate or reorient earlier fabrics. However, examination of several hundred Dalradian pelites from Connemara, western Ireland, reveals that preservation of early fabrics is by no means uncommon; relict matrix domains, although volumetrically insignificant, are remarkably persistent even when inferred later strains are very large and fabric regeneration appears, at first sight, complete. Deterministic plasticity theories are ill-suited to the analysis of such an inhomogeneous material response, and a probabilistic model is proposed instead. It assumes that ductile polycrystal deformation is controlled by elementary flow units which can be activated once their associated stress barrier is overcome. Bulk flow propensity is related to the proportion of simultaneous activations, and a measure of this is derived from the probabilistic interaction between a stress-barrier spectrum and an internal stress spectrum (the latter determined by the external loading and the details of internal stress transfer). The spectra are modelled as Gaussian distributions although the treatment is very general and could be adapted for other distributions. Using the time rate of change of activation probability it is predicted that, initially, fabric development will be rapid but will then slow down dramatically even though stress increases at a constant rate. This highly non-linear response suggests that early fabrics persist because they comprise unfavourable distributions of stress-barriers which remain unregenerated at the time bulk stress is stabilized by steady-state flow. Relict domains will, however, bear the highest stress and are potential upper

  15. [Dynamic fugacity model for describing the fate of persistent organic pollutants in the river].

    Science.gov (United States)

    Liu, Zhen-Yu; Yang, Feng-Lin; Quan, Xie; Zhang, Xiao-Hong

    2006-01-01

    Dynamic model depending on temperature with fugacity approach is formulated which describes the fate of Persistent Organic Pollutants (POPs) in a river. The fugacity capacity, the degradation rate and transfer coefficients of pollutants are depending on temperature in the model. The model is illustrated by calculating the fate of gamma-HCH in Liao River. The results show that from 273K to 298K, the fugacity capacities in air, water and sediment of gamma-HCH are respectively reduced in 8.4%, 89.7% and 89.7%. However, in the same range of temperature, the degradation rate coefficients in air, water and sediment, and volatilization and diffusion rate coefficients of gamma-HCH are increased in 0.69, 22.0, 4.5, 7.9 and 1.6 times, respectively. The calculated value agree well with the field observed value in the order of magnitude, which shows that the model is appropriate for simulating the fate of POPs in a long time.

  16. Retrospective Analysis of Recent Flood Events With Persistent High Surface Runoff From Hydrological Modelling

    Science.gov (United States)

    Joshi, S.; Hakeem, K. Abdul; Raju, P. V.; Rao, V. V.; Yadav, A.; Diwakar, P. G.; Dadhwal, V. K.

    2014-11-01

    Floods are one of the most common and widespread disasters in India, with an estimated 40Mha of land prone to this natural disaster (National Flood Commission, India). Significant loss of property, infrastructure, livestock, public utilities resulting in large economic losses due to floods are recurrent every year in many parts of India. Flood forecasting and early warning is widely recognized and adopted as non-structural measure to lower the damages caused by the flood events. Estimating the rainfall excess that results into excessive river flow is preliminary effort in riverine flood estimation. Flood forecasting models are in general, are event based and do not fully account for successive and persistent excessive surface runoff conditions. Successive high rainfall events result in saturated soil moisture conditions, favourable for high surface runoff conditions. The present study is to explore the usefulness of hydrological model derived surface runoff, running on continuous times-step, to relate to the occurrence of flood inundation due to persistent and successive high surface runoff conditions. Variable Infiltration Capacity (VIC), a macro-scale hydrological model, was used to simulate daily runoff at systematic grid level incorporating daily meteorological data and land cover data. VIC is a physically based, semi-distributed macroscale hydrological model that represents surface and subsurface hydrologic process on spatially distributed grid cell. It explicitly represents sub-grid heterogeneity in land cover classes, taking their phenological changes into account. In this study, the model was setup for entire India using geo-spatial data available from multiple sources (NRSC, NBSS&LUP, NOAA, and IMD) and was calibrated with river discharge data from CWC at selected river basins. Using the grid-wise surface runoff estimates from the model, an algorithm was developed through a set of thresholds of successive high runoff values in order to identify grids

  17. Persistence of Salinity in Tsunami Effected Coastal Aquifers In Sri Lanka: Conceptual Models and Research Needs

    Science.gov (United States)

    Illangasekare, T. H.; Obeysekera, J.; Perera, L.; Gunatilaka, A.; Dharmagunawardane, H. A.; Liyanage, J.

    2006-12-01

    In addition to widespread destruction of life and property, December 2004 Indian Ocean tsunami also caused extensive contamination of coastal aquifers across southern Asia that may have long term implications on the availability of water to a large number of people in coastal communities who rely on groundwater as the primary source of potable water. Seawater filled domestic open dug wells and also entered the aquifers via direct infiltration during the first flooding waves and later as ponded seawater infiltrated through the permeable sands that are typical of coastal aquifers. In Sri Lanka alone, it is estimated that over 40,000 drinking water wells were either destroyed or contaminated. Data collected in monitoring wells showed drastic rise in the salinity. Immediately after the tsunami, widespread pumping of wells to remove seawater was effective in some areas, but over pumping led to upconning of the saltwater interface and rising salinity. The conceptual model developed based on the initial observations assumed the existence of salinity front at the intruding saltwater from the sea at the bottom of the aquifer and a second front created from the top of the aquifer due to the saltwater infiltration from tsunami floods. Based on this model, the expectation of local and a team of scientists from USA sponsored by NSF who visited the affected areas was that the salinity should decrease with recharge from few seasonal rains associated with monsoons. It was also assumed that the intruded seawater should have vertically mixed with the fresh water in the aquifers because of both forced and free convection, thus reducing the saltwater concentrations. However, groundwater-monitoring data that have been collected during the last two years at a selected set of field sites suggests that high salinity levels are still persisting at some locations. We hypothesize that this long persistence is due to a combination of factors that were not taken into consideration in the

  18. Persistent Unresolved Inflammation in the Mecp2-308 Female Mutated Mouse Model of Rett Syndrome

    Directory of Open Access Journals (Sweden)

    Alessio Cortelazzo

    2017-01-01

    Full Text Available Rett syndrome (RTT is a rare neurodevelopmental disorder usually caused by mutations in the X-linked gene methyl-CpG-binding protein 2 (MECP2. Several Mecp2 mutant mouse lines have been developed recapitulating part of the clinical features. In particular, Mecp2-308 female heterozygous mice, bearing a truncating mutation, are a validated model of the disease. While recent data suggest a role for inflammation in RTT, little information on the inflammatory status in murine models of the disease is available. Here, we investigated the inflammatory status by proteomic 2-DE/MALDI-ToF/ToF analyses in symptomatic Mecp2-308 female mice. Ten differentially expressed proteins were evidenced in the Mecp2-308 mutated plasma proteome. In particular, 5 positive acute-phase response (APR proteins increased (i.e., kininogen-1, alpha-fetoprotein, mannose-binding protein C, alpha-1-antitrypsin, and alpha-2-macroglobulin, and 3 negative APR reactants were decreased (i.e., serotransferrin, albumin, and apolipoprotein A1. CD5 antigen-like and vitamin D-binding protein, two proteins strictly related to inflammation, were also changed. These results indicate for the first time a persistent unresolved inflammation of unknown origin in the Mecp2-308 mouse model.

  19. Chemostat modeling of Escherichia coli persistence in conventionalized mono-associated and streptomycin-treated mice

    DEFF Research Database (Denmark)

    Rang, C.; Midtvedt, T.; Molin, Søren

    2001-01-01

    We have previously shown that Escherichia coli BJ4 has similar doubling time in mice that are mono-associated (having only the inoculated E. coli BJ4) or streptomycin-treated (having mainly gram-positive bacteria plus the inoculated E. coli BJ4). We also showed that when the mice were conventiona......We have previously shown that Escherichia coli BJ4 has similar doubling time in mice that are mono-associated (having only the inoculated E. coli BJ4) or streptomycin-treated (having mainly gram-positive bacteria plus the inoculated E. coli BJ4). We also showed that when the mice were...... the decrease in colony counts, we analyzed our previous results by a chemostat model. The analysis shows that the increasing doubling time alone is sufficient to explain the decrease in colony counts in mono- associated mice, but not in the streptomycin-treated mice. The observed decreasing rate in colony...... counts in streptomycin- treated mice is slower than predicted. Furthermore, whereas the model predicted a decrease to extinction in both mice, the E. coli persist at a frequency 10-80 times higher in streptomycin- treated mice than in mono-associated mice. Thus, while a chemostat model is able to explain...

  20. Persistent short-term memory defects following sleep deprivation in a drosophila model of Parkinson disease.

    Science.gov (United States)

    Seugnet, Laurent; Galvin, James E; Suzuki, Yasuko; Gottschalk, Laura; Shaw, Paul J

    2009-08-01

    Parkinson disease (PD) is the second most common neurodegenerative disorder in the United States. It is associated with motor deficits, sleep disturbances, and cognitive impairment. The pathology associated with PD and the effects of sleep deprivation impinge, in part, upon common molecular pathways suggesting that sleep loss may be particularly deleterious to the degenerating brain. Thus we investigated the long-term consequences of sleep deprivation on shortterm memory using a Drosophila model of Parkinson disease. Transgenic strains of Drosophila melanogaster. Using the GAL4-UAS system, human alpha-synuclein was expressed throughout the nervous system of adult flies. Alpha-synuclein expressing flies (alpha S flies) and the corresponding genetic background controls were sleep deprived for 12 h at age 16 days and allowed to recover undisturbed for at least 3 days. Short-term memory was evaluated using aversive phototaxis suppression. Dopaminergic systems were assessed using mRNA profiling and immunohistochemistry. MEASURMENTS AND RESULTS: When sleep deprived at an intermediate stage of the pathology, alpha S flies showed persistent short-term memory deficits that lasted > or = 3 days. Cognitive deficits were not observed in younger alpha S flies nor in genetic background controls. Long-term impairments were not associated with accelerated loss of dopaminergic neurons. However mRNA expression of the dopamine receptors dDA1 and DAMB were significantly increased in sleep deprived alpha S flies. Blocking D1-like receptors during sleep deprivation prevented persistent shortterm memory deficits. Importantly, feeding flies the polyphenolic compound curcumin blocked long-term learning deficits. These data emphasize the importance of sleep in a degenerating/reorganizing brain and shows that pathological processes induced by sleep deprivation can be dissected at the molecular and cellular level using Drosophila genetics.

  1. Winter NH low-frequency variability in a hierarchy of low-order stochastic dynamical models of earth-atmosphere system

    Science.gov (United States)

    Zhao, Nan

    2018-02-01

    The origin of winter Northern Hemispheric low-frequency variability (hereafter, LFV) is regarded to be related to the coupled earth-atmosphere system characterized by the interaction of the jet stream with mid-latitude mountain ranges. On the other hand, observed LFV usually appears as transitions among multiple planetary-scale flow regimes of Northern Hemisphere like NAO + , AO +, AO - and NAO - . Moreover, the interaction between synoptic-scale eddies and the planetary-scale disturbance is also inevitable in the origin of LFV. These raise a question regarding how to incorporate all these aspects into just one framework to demonstrate (1) a planetary-scale dynamics of interaction of the jet stream with mid-latitude mountain ranges can really produce LFV, (2) such a dynamics can be responsible for the existence of above multiple flow regimes, and (3) the role of interaction with eddy is also clarified. For this purpose, a hierarchy of low-order stochastic dynamical models of the coupled earth-atmosphere system derived empirically from different timescale ranges of indices of Arctic Oscillation (AO), North Atlantic Oscillation (NAO), Pacific/North American (PNA), and length of day (LOD) and related probability density function (PDF) analysis are employed in this study. The results seem to suggest that the origin of LFV cannot be understood completely within the planetary-scale dynamics of the interaction of the jet stream with mid-latitude mountain ranges, because (1) the existence of multiple flow regimes such as NAO+, AO+, AO- and NAO- resulted from processes with timescales much longer than LFV itself, which may have underlying dynamics other than topography-jet stream interaction, and (2) we find LFV seems not necessarily to come directly from the planetary-scale dynamics of the interaction of the jet stream with mid-latitude mountain, although it can produce similar oscillatory behavior. The feedback/forcing of synoptic-scale eddies on the planetary

  2. Prolonged persistence of bovine herpesvirus in small cattle herds: a model-based analysis

    NARCIS (Netherlands)

    Mollema, E.; Jong, de M.C.M.; Boven, van R.M.

    2005-01-01

    Herpesviruses can remain dormant in once-infected hosts and, upon reactivation, cause such hosts to become infectious. This phenomenon of latency and reactivation may enable herpesviruses to persist for a long time in small host populations. To quantify the effect of reactivation on persistence, the

  3. Chemostat modeling of Escherichia coli persistence in conventionalized mono-associated and streptomycin-treated mice

    DEFF Research Database (Denmark)

    Rang, C.; Midtvedt, T.; Molin, Søren

    2001-01-01

    conventionalization, we take these results to suggest that the persistence of E. coli populations is promoted by species diversity. We propose that a mechanism for the persistence may be the presence of new E. coli niches created by keystone species in the more diverse flora....

  4. 3D Normal Human Neural Progenitor Tissue-Like Assemblies: A Model of Persistent VZV Infection

    Science.gov (United States)

    Goodwin, Thomas J.

    2013-01-01

    Varicella-zoster virus (VZV) is a neurotropic human alphaherpesvirus that causes varicella upon primary infection, establishes latency in multiple ganglionic neurons, and can reactivate to cause zoster. Live attenuated VZV vaccines are available; however, they can also establish latent infections and reactivate. Studies of VZV latency have been limited to the analyses of human ganglia removed at autopsy, as the virus is strictly a human pathogen. Recently, terminally differentiated human neurons have received much attention as a means to study the interaction between VZV and human neurons; however, the short life-span of these cells in culture has limited their application. Herein, we describe the construction of a model of normal human neural progenitor cells (NHNP) in tissue-like assemblies (TLAs), which can be successfully maintained for at least 180 days in three-dimensional (3D) culture, and exhibit an expression profile similar to that of human trigeminal ganglia. Infection of NHNP TLAs with cell-free VZV resulted in a persistent infection that was maintained for three months, during which the virus genome remained stable. Immediate-early, early and late VZV genes were transcribed, and low-levels of infectious VZV were recurrently detected in the culture supernatant. Our data suggest that NHNP TLAs are an effective system to investigate long-term interactions of VZV with complex assemblies of human neuronal cells.

  5. Quantitative models of persistence and relapse from the perspective of behavioral momentum theory: Fits and misfits.

    Science.gov (United States)

    Nevin, John A; Craig, Andrew R; Cunningham, Paul J; Podlesnik, Christopher A; Shahan, Timothy A; Sweeney, Mary M

    2017-08-01

    We review quantitative accounts of behavioral momentum theory (BMT), its application to clinical treatment, and its extension to post-intervention relapse of target behavior. We suggest that its extension can account for relapse using reinstatement and renewal models, but that its application to resurgence is flawed both conceptually and in its failure to account for recent data. We propose that the enhanced persistence of target behavior engendered by alternative reinforcers is limited to their concurrent availability within a distinctive stimulus context. However, a failure to find effects of stimulus-correlated reinforcer rates in a Pavlovian-to-Instrumental Transfer (PIT) paradigm challenges even a straightforward Pavlovian account of alternative reinforcer effects. BMT has been valuable in understanding basic research findings and in guiding clinical applications and accounting for their data, but alternatives are needed that can account more effectively for resurgence while encompassing basic data on resistance to change as well as other forms of relapse. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. Stability and disease persistence in an age-structured SIS epidemic model with vertical transmission and proportionate mixing assumption

    International Nuclear Information System (INIS)

    El-Doma, M.

    2001-02-01

    The stability of the endemic equilibrium of an SIS age-structured epidemic model of a vertically as well as horizontally transmitted disease is investigated when the force of infection is of proportionate mixing assumption type. We also investigate the uniform weak disease persistence. (author)

  7. Predicting fadeout versus persistence of paratuberculosis in a dairy cattle herd for management and control purposes: a modelling study

    Directory of Open Access Journals (Sweden)

    Marcé Clara

    2011-02-01

    Full Text Available Abstract Epidemiological models enable to better understand the dynamics of infectious diseases and to assess ex-ante control strategies. For Mycobacterium avium subsp. paratuberculosis (Map, possible transmission routes have been described, but Map spread in a herd and the relative importance of the routes are currently insufficiently understood to prioritize control measures. We aim to predict early after Map introduction in a dairy cattle herd whether infection is likely to fade out or persist, when no control measures are implemented, using a modelling approach. Both vertical transmission and horizontal transmission via the ingestion of colostrum, milk, or faeces present in the contaminated environment were modelled. Calf-to-calf indirect transmission was possible. Six health states were represented: susceptible, transiently infectious, latently infected, subclinically infected, clinically affected, and resistant. The model was partially validated by comparing the simulated prevalence with field data. Housing facilities and contacts between animals were specifically considered for calves and heifers. After the introduction of one infected animal in a naive herd, fadeout occurred in 66% of the runs. When Map persisted, the prevalence of infected animals increased to 88% in 25 years. The two main transmission routes were via the farm's environment and in utero transmission. Calf-to-calf transmission was minor. Fadeout versus Map persistence could be differentiated with the number of clinically affected animals, which was rarely above one when fadeout occurred. Therefore, early detection of affected animals is crucial in preventing Map persistence in dairy herds.

  8. Testing Hypotheses in an I(2) Model with Applications to the Persistent Long Swings in the Dmk/$ Rate

    DEFF Research Database (Denmark)

    Johansen, Søren; Juselius, Katarina; Frydman, Roman

    and persistent swings in the foreign exchange market between Germany and USA. The data analyzed consist of nominal exchange rates, relative prices, US inflation rate, two long-term interest rates and two short-term interest rates over the 1975-1999 period. One important aim of the paper is to demonstrate...... that by structuring the data with the help of the I(2) model one can achieve a better understanding of the empirical regularities underlying the persistent swings in nominal exchange rates, typical in periods of floating exchange rates...

  9. Enabling Persistent Autonomy for Underwater Gliders with Ocean Model Predictions and Terrain Based Navigation

    Directory of Open Access Journals (Sweden)

    Andrew eStuntz

    2016-04-01

    Full Text Available Effective study of ocean processes requires sampling over the duration of long (weeks to months oscillation patterns. Such sampling requires persistent, autonomous underwater vehicles, that have a similarly long deployment duration. The spatiotemporal dynamics of the ocean environment, coupled with limited communication capabilities, make navigation and localization difficult, especially in coastal regions where the majority of interesting phenomena occur. In this paper, we consider the combination of two methods for reducing navigation and localization error; a predictive approach based on ocean model predictions and a prior information approach derived from terrain-based navigation. The motivation for this work is not only for real-time state estimation, but also for accurately reconstructing the actual path that the vehicle traversed to contextualize the gathered data, with respect to the science question at hand. We present an application for the practical use of priors and predictions for large-scale ocean sampling. This combined approach builds upon previous works by the authors, and accurately localizes the traversed path of an underwater glider over long-duration, ocean deployments. The proposed method takes advantage of the reliable, short-term predictions of an ocean model, and the utility of priors used in terrain-based navigation over areas of significant bathymetric relief to bound uncertainty error in dead-reckoning navigation. This method improves upon our previously published works by 1 demonstrating the utility of our terrain-based navigation method with multiple field trials, and 2 presenting a hybrid algorithm that combines both approaches to bound navigational error and uncertainty for long-term deployments of underwater vehicles. We demonstrate the approach by examining data from actual field trials with autonomous underwater gliders, and demonstrate an ability to estimate geographical location of an underwater glider to 2

  10. The German model of capitalism and the persistence of outward foreign direct investment: evidence from German manufacturing industries

    Directory of Open Access Journals (Sweden)

    Martin T Bohl

    2011-06-01

    Full Text Available Against the backdrop of critique on the German model of capitalism in general, and German public policy in particular as to the ability to successfully adjust to rapid change and exogenous shocks in wake of economic globalisation, this paper investigates the degree of shock persistence in foreign direct investment (FDI of ten German manufacturing industries for the period 1976 to 2003. Theory on exports and non-FDI investment suggests that FDI should exhibit a considerable degree of shock persistence because they are subject to high sunk costs because of high entry and exit costs associated with the high level of asset specificity that is normally connected to FDI. Persistence in foreign direct investment time series data is established by applying various unit root tests. The results are robust to the potential presence of structural breaks in the data. The empirical analysis shows that German outward FDI in mature manufacturing industries, with one exception, exhibits a high degree of shock persistence. The results suggest, at least for mature German industries, that the sunk costs view on shock persistency is confirmed for outward FDI. The results furnish evidence for a tentative assessment of the relationship between German public policy and FDI strategies of multinational firms.

  11. A trap-limited-current-based model of Meyer–Neldel rule and its connection to persistent photocurrent

    International Nuclear Information System (INIS)

    Tian, Ye; Jiang, Lianjun; Zhang, Xuejun; Zhang, Guangfu

    2016-01-01

    A theoretical model is established to describe the emergence of the Meyer–Neldel rule (MNR) based on trap-limited current (TLC) theory. The model produces both MNR and anti-MNR behavior, and is available to various trap distributions. Moreover, TLC-based MNR is connected to persistent photocurrent (PPC) phenomenon. The information from MNR and PPC as well as their connection can be used to probe the distribution of the traps in materials. (paper)

  12. Determination of humidity and temperature fluctuations based on MOZAIC data and parametrisation of persistent contrail coverage for general circulation models

    Directory of Open Access Journals (Sweden)

    K. M. Gierens

    1997-08-01

    Full Text Available Humidity and temperature fluctuations at pressure levels between 166 and 290 hPa on the grid scale of general circulation models for a region covered by the routes of airliners, mainly over the Atlantic, have been determined by evaluation of the data obtained with almost 2000 flights within the MOZAIC programme. It is found that the distributions of the fluctuations cannot be modelled by Gaussian distributions, because large fluctuations appear with a relatively high frequency. Lorentz distributions were used for the analytical representation of the fluctuation distributions. From these a joint probability distribution has been derived for simultaneous temperature and humidity fluctuations. This function together with the criteria for the formation and persistence of contrails are used to derive the maximum possible fractional coverage of persistent contrails in a grid cell of a GCM. This can be employed in a statistical formulation of contrail appearance in a climate model.

  13. Testing hypotheses in an I(2) model with applications to the persistent long swings in the Dmk/$ rate

    DEFF Research Database (Denmark)

    Johansen, Søren; Juselius, Katarina; Frydman, Roman

    components in the I(2) model is discussed at some length. Model specification and tests are illustrated with an empirical analysis of long and persistent swings in the foreign exchange market between Germany and USA. The data analyzed consist of nominal exchange rates, relative prices, US inflation rate, two...... in nominal exchange rates, typical in periods of floating exchange rates....... long-term interest rates and two short-term interest rates over the 1975-1999 period. One important aim of the paper is to demonstrate that by structuring the data with the help of the I(2) model one can achieve a better understanding of the empirical regularities underlying the persistent swings...

  14. Indicators of Persistence for Hispanic Undergraduate Achievement: Toward an Ecological Model

    Science.gov (United States)

    Arana, Renelinda; Castaneda-Sound, Carrie; Blanchard, Steve; Aguilar, Teresita E.

    2011-01-01

    By examining Hispanic students both currently and formerly enrolled at a private, Hispanic-serving Institution located in the Southwestern region of the United States, this study attempts to understand the factors that lead to Hispanic undergraduate persistence to graduation. Adapting Bronfenbrenner's theoretical approach, this study explores…

  15. The Oklahoma's Promise Program: A National Model to Promote College Persistence

    Science.gov (United States)

    Mendoza, Pilar; Mendez, Jesse P.

    2013-01-01

    Using a multi-method approach involving fixed effects and logistic regressions, this study examined the effect of the Oklahoma's Promise Program on student persistence in relation to the Pell and Stafford federal programs and according to socio-economic characteristics and class level. The Oklahoma's Promise is a hybrid state program that pays…

  16. Viral persistence, liver disease and host response in Hepatitis C-like virus rat model

    DEFF Research Database (Denmark)

    Trivedi, Sheetal; Murthy, Satyapramod; Sharma, Himanshu

    2018-01-01

    inflammation and macro/micro vesicular steatosis in chronically infected rats. Gene expression analysis demonstrated that the intrahepatic response during RHV-rn1 infection in rats mirrors that of HCV infection, including persistent activation of interferon signaling pathways. Finally, we determined......, immunity and pathogenesis. This article is protected by copyright. All rights reserved....

  17. Effects of a population floor on the persistence of chaos in a mutual interference host-parasitoid model

    Energy Technology Data Exchange (ETDEWEB)

    Zhao Min [College of Agriculture and Biotechnology, Zhejiang University, Hangzhou 310029, Zhejiang (China); School of Life and Environmental Sciences, Wenzhou University, Wenzhou 325035, Zhejiang (China)], E-mail: zmcn@tom.com; Yu Hengguo [School of Mathematics and Information Science, Wenzhou University, Wenzhou 325035, Zhejiang (China); Zhu Jun [College of Agriculture and Biotechnology, Zhejiang University, Hangzhou 310029, Zhejiang (China)

    2009-10-30

    Chaotic dynamics have been observed in a wide range of population models. However, much of the research on the persistence of chaos has focused on external perturbations of ecosystems, such as climatic change or anthropogenic factors. In this paper, the effects of a non-zero population floor in a mutual interference host-parasitoid model are described. Such a perturbation generally reduces the likelihood of observing chaos. Furthermore, the computational simulation of the largest Lyapunov exponent also demonstrates the chaotic dynamic behavior of the model and describes a process which reduces the likelihood of observing chaos. The numerical results indicate that computer simulation is a useful method for studying chaos.

  18. Costs and longer-term savings of parenting programmes for the prevention of persistent conduct disorder: a modelling study

    Directory of Open Access Journals (Sweden)

    Beecham Jennifer

    2011-10-01

    Full Text Available Abstract Background Conduct disorders are the most common psychiatric disorders in children and may persist into adulthood in about 50% of cases. The costs to society are high and impact many public sector agencies. Parenting programmes have been shown to positively affect child behaviour, but little is known about their potential long-term cost-effectiveness. We therefore estimate the costs of and longer-term savings from evidence-based parenting programmes for the prevention of persistent conduct disorder. Methods A decision-analytic Markov model compares two scenarios: 1 a 5-year old with clinical conduct disorder receives an evidence-based parenting programme; 2 the same 5-year old does not receive the programme. Cost-savings analysis is performed by comparing the probability that conduct disorder persists over time in each scenario, adopting both a public sector and a societal perspective. If the intervention is successful in reducing persistent conduct disorder, cost savings may arise from reduced use of health services, education support, social care, voluntary agencies and from crimes averted. Results Results strongly suggest that parenting programmes reduce the chance that conduct disorder persists into adulthood and are cost-saving to the public sector within 5-8 years under base case conditions. Total savings to society over 25 years are estimated at £16,435 per family, which compares with an intervention cost in the range of £952-£2,078 (2008/09 prices. Conclusions Effective implementation of evidence-based parenting programmes is likely to yield cost savings to the public sector and society. More research is needed to address evidence gaps regarding the current level of provision, longer-term effectiveness and questions of implementation, engagement and equity.

  19. Location of persisting mycobacteria in a Guinea pig model of tuberculosis revealed by r207910.

    Science.gov (United States)

    Lenaerts, Anne J; Hoff, Donald; Aly, Sahar; Ehlers, Stefan; Andries, Koen; Cantarero, Luis; Orme, Ian M; Basaraba, Randall J

    2007-09-01

    The lengthy chemotherapy of tuberculosis reflects the ability of a small subpopulation of Mycobacterium tuberculosis bacteria to persist in infected individuals. To date, the exact location of these persisting bacteria is not known. Lung lesions in guinea pigs infected with M. tuberculosis have striking similarities, such as necrosis, mineralization, and hypoxia, to natural infections in humans. Guinea pigs develop necrotic primary lesions after aerosol infection that differ in their morphology compared to secondary lesions resulting from hematogenous dissemination. In infected guinea pigs conventional therapy for tuberculosis during 6 weeks reduced the bacterial load by 1.7 logs in the lungs and, although this completely reversed lung inflammation associated with secondary lesions, the primary granulomas remained largely unaffected. Treatment of animals with the experimental drug R207910 (TMC207) for 6 weeks was highly effective with almost complete eradication of the bacteria throughout both the primary and the secondary lesions. Most importantly, the few remnants of acid-fast bacilli remaining after R207910 treatment were to be found extracellular, in a microenvironment of residual primary lesion necrosis with incomplete dystrophic calcification. This zone of the primary granuloma is hypoxic and is morphologically similar to what has been described for human lung lesions. These results show that this acellular rim may, therefore, be a primary location of persisting bacilli withstanding drug treatment.

  20. Location of Persisting Mycobacteria in a Guinea Pig Model of Tuberculosis Revealed by R207910▿

    Science.gov (United States)

    Lenaerts, Anne J.; Hoff, Donald; Aly, Sahar; Ehlers, Stefan; Andries, Koen; Cantarero, Luis; Orme, Ian M.; Basaraba, Randall J.

    2007-01-01

    The lengthy chemotherapy of tuberculosis reflects the ability of a small subpopulation of Mycobacterium tuberculosis bacteria to persist in infected individuals. To date, the exact location of these persisting bacteria is not known. Lung lesions in guinea pigs infected with M. tuberculosis have striking similarities, such as necrosis, mineralization, and hypoxia, to natural infections in humans. Guinea pigs develop necrotic primary lesions after aerosol infection that differ in their morphology compared to secondary lesions resulting from hematogenous dissemination. In infected guinea pigs conventional therapy for tuberculosis during 6 weeks reduced the bacterial load by 1.7 logs in the lungs and, although this completely reversed lung inflammation associated with secondary lesions, the primary granulomas remained largely unaffected. Treatment of animals with the experimental drug R207910 (TMC207) for 6 weeks was highly effective with almost complete eradication of the bacteria throughout both the primary and the secondary lesions. Most importantly, the few remnants of acid-fast bacilli remaining after R207910 treatment were to be found extracellular, in a microenvironment of residual primary lesion necrosis with incomplete dystrophic calcification. This zone of the primary granuloma is hypoxic and is morphologically similar to what has been described for human lung lesions. These results show that this acellular rim may, therefore, be a primary location of persisting bacilli withstanding drug treatment. PMID:17517834

  1. A new model mimicking persistent HBV e antigen-negative infection using covalently closed circular DNA in immunocompetent mice.

    Directory of Open Access Journals (Sweden)

    Lei Wang

    Full Text Available Despite the availability of an effective vaccine, hepatitis B virus (HBV infection remains a major health problem. HBV e antigen (HBeAg-negative strains have become prevalent. Previously, no animal model mimicked the clinical course of HBeAg-negative HBV infection. To establish an HBeAg-negative HBV infection model, the 3.2-kb full-length genome of HBeAg-negative HBV was cloned from a clinical sample and then circularized to form covalently closed circular (cccDNA. The resulting cccDNA was introduced into the liver of C57BL/6J mice through hydrodynamic injection. Persistence of the HBeAg-negative infection was monitored at predetermined time points using HBV-specific markers including HBV surface antigen (HBsAg, HBeAg, and HBV core antigen (HBcAg as well as DNA copies. Throughout the study, pAAV-HBV1.2 was used as a control. In mice injected with HBeAg-negative cccDNA, the HBV infection rate was 100% at the initial stage. HBsAg levels increased up to 1 week, at which point levels peaked and dropped quickly thereafter. In 60% of injected mice, HBsAg and HBcAg persisted for more than 10 weeks. High numbers of HBV DNA copies were detected in the serum and liver. Moreover, cccDNA persisted in the liver tissue of HBeAg-negative mice. In contrast to the pAAV-HBV 1.2 injected mice, no HBeAg was found in mice injected with HBeAg-negative HBV throughout the study period. These results demonstrate the first successful establishment of a model of HBeAg-negative HBV-persistent infection in immunocompetent mice. Compared to pAAV-HBV1.2-injected mice, the infection persistence and levels of serum virological and biochemical markers were approximately equal in the model mice. This model will be useful for mechanistic studies on HBeAg-negative HBV infection and will facilitate the evaluation of new antiviral drugs.

  2. A new model of Hantaan virus persistence in mice: the balance between HTNV infection and CD8+ T-cell responses

    International Nuclear Information System (INIS)

    Araki, Koichi; Yoshimatsu, Kumiko; Lee, Byoung-Hee; Kariwa, Hiroaki; Takashima, Ikuo; Arikawa, Jiro

    2004-01-01

    We established a viral persistence model that involves the adoptive transfer of spleen cells from immunocompetent mice (H-2 d ) into Hantaan virus (HTNV)-infected severe combined immunodeficient (SCID, H-2 d ) mice. The infection is maintained despite the presence of neutralizing antibodies, without apparent signs of disease, and there is a correlation between HTNV persistence and the lack of HTNV-specific CD8 + T cells. In addition, disseminated HTNV infection before the initiation of immune responses appears to be important for virus persistence. The suppression of HTNV-specific CD8 + T cells in the present model appears to occur at the periphery. The present study also demonstrates that CD8 + T cells contribute to the clearance of HTNV. Thus, it seems that HTNV-specific CD8 + T cells play a key role in HTNV persistence in mice. This model of viral persistence is useful for studies of immune responses and immunocytotherapy against viral infection

  3. Modeling the long-term persistence of hepatitis A antibody after a two-dose vaccination schedule in Argentinean children.

    Science.gov (United States)

    López, Eduardo L; Contrini, María Marta; Mistchenko, Alicia; Kieffer, Alexia; Baggaley, Rebecca F; Di Tanna, Gian Luca; Desai, Kamal; Rasuli, Anvar; Armoni, Judith

    2015-04-01

    Long-term seroprotection data are essential for decision-making on the need and timing of vaccine boosters. Based on data from longitudinal serological studies, modeling can provide estimates on long-term antibody persistence and inform such decision-making. We examined long-term anti-hepatitis A virus (anti-HAV) antibody persistence in Argentinean children ≤15 years after the initial study where they completed a 2-dose course of inactivated hepatitis A vaccine (Avaxim 80U Pediatric, Sanofi Pasteur, Lyon, France). Blood serum samples were taken at baseline, 2 weeks (post first dose), 6 months (pre-booster), 6.5 months (post-booster), 10 years and 14-15 years after first vaccine dose. We fitted 8 statistical model types, predominantly mixed effects models, to anti-HAV persistence data, to identify the most appropriate and best fitting models for our data set and to predict individuals' anti-HAV levels and seroprotection rates up to 30 years post vaccination. Fifty-four children (mean age at enrollment 30.4 months) were enrolled up to 15 years post first vaccine dose. There were 3 distinct periods of antibody concentration: rapid rise up to peak concentration post-booster, rapid decay from post-booster to 10 years, followed by slower decay. A 3-segmented linear mixed effects model was the most appropriate for the data set. Extrapolating based on the available 14-15-year follow-up, the analysis predicted that 88% of individuals anti-HAV seronegative prior to vaccination would remain seroprotected at 30 years post vaccination and lifelong seroprotection for vaccinees seropositive prior to vaccination. Currently available data demonstrate that Avaxim 80U Pediatric confers to most vaccinees a high level of seroprotection against hepatitis A infection for at least 20-30 years.

  4. The persistence of subsistence: qualitative social-ecological modeling of indigenous aquatic hunting and gathering in tropical Australia

    Directory of Open Access Journals (Sweden)

    Marcus Barber

    2015-03-01

    Full Text Available Subsistence remains critical to indigenous people in settler-colonial states such as Australia, providing key foundations for indigenous identities and for wider state recognition. However, the drivers of contemporary subsistence are rarely fully articulated and analyzed in terms of likely changing conditions. Our interdisciplinary team combined past research experience gained from multiple sites with published literature to create two generalized qualitative models of the socio-cultural and environmental influences on indigenous aquatic subsistence in northern Australia. One model focused on the longer term (inter-year to generational persistence of subsistence at the community scale, the other model on shorter term (day to season drivers of effort by active individuals. The specification of driver definitions and relationships demonstrates the complexities of even generalized and materialist models of contemporary subsistence practices. The qualitative models were analyzed for emergent properties and for responses to plausible changes in key variables: access, habitat degradation, social security availability, and community dysfunction. Positive human community condition is shown to be critical to the long-term persistence of subsistence, but complex interactions of negative and positive drivers shape subsistence effort expended at the individual scale and within shorter time frames. Such models enable motivations, complexities, and the potential management and policy levers of significance to be identified, defined, causally related, and debated. The models can be used to augment future models of human-natural systems, be tested against case-specific field conditions and/or indigenous perspectives, and aid preliminary assessments of the effects on subsistence of changes in social and environmental conditions, including policy settings.

  5. Overly persistent circulation in climate models contributes to overestimated frequency and duration of heat waves and cold spells

    Czech Academy of Sciences Publication Activity Database

    Plavcová, Eva; Kyselý, Jan

    2016-01-01

    Roč. 46, č. 9 (2016), s. 2805-2820 ISSN 0930-7575 R&D Projects: GA ČR GAP209/10/2265; GA MŠk 7AMB15AR001 EU Projects: European Commission(XE) 505539 - ENSEMBLES Program:FP6 Institutional support: RVO:68378289 Keywords : heat wave * cold spell * atmospheric circulation * persistence * regional climate models * Central Europe Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 4.146, year: 2016 http://link.springer.com/article/10.1007%2Fs00382-015-2733-8

  6. Rapid development of entity-based data models for bioinformatics with persistence object-oriented design and structured interfaces.

    Science.gov (United States)

    Ezra Tsur, Elishai

    2017-01-01

    Databases are imperative for research in bioinformatics and computational biology. Current challenges in database design include data heterogeneity and context-dependent interconnections between data entities. These challenges drove the development of unified data interfaces and specialized databases. The curation of specialized databases is an ever-growing challenge due to the introduction of new data sources and the emergence of new relational connections between established datasets. Here, an open-source framework for the curation of specialized databases is proposed. The framework supports user-designed models of data encapsulation, objects persistency and structured interfaces to local and external data sources such as MalaCards, Biomodels and the National Centre for Biotechnology Information (NCBI) databases. The proposed framework was implemented using Java as the development environment, EclipseLink as the data persistency agent and Apache Derby as the database manager. Syntactic analysis was based on J3D, jsoup, Apache Commons and w3c.dom open libraries. Finally, a construction of a specialized database for aneurysms associated vascular diseases is demonstrated. This database contains 3-dimensional geometries of aneurysms, patient's clinical information, articles, biological models, related diseases and our recently published model of aneurysms' risk of rapture. Framework is available in: http://nbel-lab.com.

  7. Interpreting the R K (*) anomaly in the colored Zee-Babu model

    Science.gov (United States)

    Guo, Shu-Yuan; Han, Zhi-Long; Li, Bin; Liao, Yi; Ma, Xiao-Dong

    2018-03-01

    We consider the feasibility of interpreting the R K (*) anomaly in the colored Zee-Babu model. The model generates neutrino masses at two loops with the help of a scalar leptoquark S ∼ (3 , 3 , - 1/3) and a scalar diquark ω ∼ (6 , 1 , - 2/3), and contributes to the transition b → sℓ-ℓ+ via the exchange of a leptoquark S at tree level. Under constraints from lepton flavor violating (LFV) and flavor changing neutral current (FCNC) processes, and direct collider searches for heavy particles, we acquire certain parameter space that can accommodate the R K (*) anomaly for both normal (NH) and inverted (IH) hierarchies of neutrino masses. We further examine the LFV decays of the B meson, and find a strong correlation with the neutrino mass hierarchy, i.e., Br (B+ →K+μ±τ∓) ≳Br (B+ →K+μ±e∓) ≈Br (B+ →K+τ±e∓) for NH, while Br (B+ →K+μ±τ∓) ≪Br (B+ →K+μ±e∓) ≈Br (B+ →K+τ±e∓) for IH. Among these decays, only B+ →K+μ±e∓ in the case of NH is promising at the LHCb RUN II, while for IH all LFV decays are hard to detect in the near future.

  8. [Persistent diarrhea

    Science.gov (United States)

    Andrade, J A; Moreira, C; Fagundes Neto, U

    2000-07-01

    INTRODUCTION: Persistent diarrhea has high impact on infantile morbidity and mortality rates in developing countries. Several studies have shown that 3 to 20% of acute diarrheal episodes in children under 5 years of age become persistent. DEFINITION: Persistent diarrhea is defined as an episode that lasts more than 14 days. ETIOLOGY: The most important agents isolated in persistent diarrhea are: Enteropathogenic E. coli (EPEC), Salmonella, Enteroaggregative E. coli (EAEC), Klebisiella and Cryptosporidium. CLINICAL ASPECTS: In general, the clinical characteristics of patients with persistent diarrhea do not change with the pathogenic agent. Persistent diarrhea seems to represent the final result of a several insults a infant suffers that predisposes to a more severe episode of diarrhea due to a combination of host factors and high rates of enviromental contamination. Therefore, efforts should be made to promptly treat all episodes of diarrhea with apropriate follow-up. THERAPY: The aim of the treatment is to restore hydroelectrolytic deficits and to replace losses until the diarrheal ceases. It is possible in the majority of the cases, using oral rehydration therapy and erly an appropriate type of diet. PREVENTION: It is imperative that management strategies also focus on preventive aspects. The most effective diarrheal prevention strategy in young infants worldwide is promotion of exclusive breast feeding.

  9. Impact of multi-layer soil model on the simulation of persistent organic pollutant fate at european scale

    International Nuclear Information System (INIS)

    Loizeau, Vincent

    2014-01-01

    Persistent Organic Pollutants (POPs) are toxic substances that bio-accumulate in the food chain. Once emitted in the atmosphere, they are transported by the wind and deposited on soil. Since they are persistent, they can be re-emitted from soil to atmosphere by volatilization and travel over very long distances. This process is called grasshopper effect. Thus, POPs may be found at significant levels far from their emission source. It is necessary to understand the transport and fate of these pollutants in order to support the decision making process and reduce human exposure to POPs. Regulations over the last decades lead to a decrease of anthropogenic emissions and subsequent decrease of atmospheric concentration. In this context, the soil is no longer a sink of POPs but can be a source to the atmosphere. Many numeric models aim to study the behavior of POPs in the environment. Most of them consider soil compartment as a homogeneous box, leading to an underestimation of re-emissions. Then, it appears of great importance to develop more realistic soil models. The objective of my thesis was to develop such a model, with vertical transport within the soil. This model was evaluated against measured concentration soil profile. We also conducted a sensitivity analysis to identify the key parameters involved in the process of re-emissions. Then, the soil model was coupled with an atmospheric transport model. A case study was finally undertaken to estimate the impacts of re-emissions on global-mass balance of POPs at European scale. (author) [fr

  10. Viral persistence, latent reservoir, and blips: a review on HIV-1 dynamics and modeling during HAART and related treatment implications

    Energy Technology Data Exchange (ETDEWEB)

    Rong, Libin [Los Alamos National Laboratory; Perelson, Alan [Los Alamos National Laboratory

    2008-01-01

    HIV-1 eradication from infected individuals has not been achieved with the use of highly active antiretroviral therapy (HAART) for a prolonged period of time. The cellular reservoir for HIV-1 in resting memory CD4{sup +} T cells remains a major obstacle to viral elimination. The reservoir does not decay significantly over long periods of time as is able to release replication competent HIV-1 upon cell activation. Residual ongoing viral replication may likely occur in many patients because low levels of virus can be detected in plasma by sensitive assays and transient episodes of viremia, or HIV-1 blips, are often observed in patients even with successful viral suppression for many years. Here we review our current knowledge of the factors contributing to viral persistence, the latent reservoir, and blips, and mathematical models developed to explore them and their relationships. We show how mathematical modeling can help improve our understanding of HIV-1 dynamics in patients on HAART and the quantitative events underlying HIV-1 latency, reservoir stability, low-level viremic persistence, and emergence of intermittent viral blips. We also discuss treatment implications related to these studies.

  11. Measurements and Modeling of Turbulent Fluxes during Persistent Cold Air Pool Events in Salt Lake Valley, Utah

    Science.gov (United States)

    Ivey, C. E.; Sun, X.; Holmes, H.

    2017-12-01

    Land surface processes are important in meteorology and climate research since they control the partitioning of surface energy and water exchange at the earth's surface. The surface layer is coupled to the planetary boundary layer (PBL) by surface fluxes, which serve as sinks or sources of energy, moisture, momentum, and atmospheric pollutants. Quantifying the surface heat and momentum fluxes at the land-atmosphere interface, especially for different surface land cover types, is important because they can further influence the atmospheric dynamics, vertical mixing, and transport processes that impact local, regional, and global climate. A cold air pool (CAP) forms when a topographic depression (i.e., valley) fills with cold air, where the air in the stagnant layer is colder than the air aloft. Insufficient surface heating, which is not able to sufficiently erode the temperature inversion that forms during the nighttime stable boundary layer, can lead to the formation of persistent CAPs during wintertime. These persistent CAPs can last for days, or even weeks, and are associated with increased air pollution concentrations. Thus, realistic simulations of the land-atmosphere exchange are meaningful to achieve improved predictions of the accumulation, transport, and dispersion of air pollution concentrations. The focus of this presentation is on observations and modeling results using turbulence data collected in Salt Lake Valley, Utah during the 2010-2011 wintertime Persistent Cold Air Pool Study (PCAPS). Turbulent fluxes and the surface energy balance over seven land use types are quantified. The urban site has an energy balance ratio (EBR) larger than one (1.276). Negative Bowen ratio (-0.070) is found at the cropland site. In addition to turbulence observations, half-hourly WRF simulated net radiation, latent heat, sensible heat, ground heat fluxes during one persistent CAP event are evaluated using the PCAPS observations. The results show that sensible and latent

  12. Mixed infections with Chlamydia and porcine epidemic diarrhea virus - a new in vitro model of chlamydial persistence.

    Science.gov (United States)

    Borel, Nicole; Dumrese, Claudia; Ziegler, Urs; Schifferli, Andrea; Kaiser, Carmen; Pospischil, Andreas

    2010-07-27

    Chlamydiae induce persistent infections, which have been associated with a wide range of chronic diseases in humans and animals. Mixed infections with Chlamydia and porcine epidemic diarrhea virus (PEDV) may result in generation of persistent chlamydial infections. To test this hypothesis, an in vitro model of dual infection with cell culture-adapted PEDV and Chlamydia abortus or Chlamydia pecorum in Vero cells was established. Infected cultures were investigated by immunofluorescence (IF), transmission electron microscopy (TEM) and re-infection experiments. By IF, Chlamydia-infected cells showed normal inclusions after 39 hpi. Dual infections with Chlamydia abortus revealed a heterogenous mix of inclusion types including small inclusions consisting of aberrant bodies (ABs), medium-sized inclusions consisting of ABs and reticulate bodies and normal inclusions. Only aberrant inclusions were observable in dual infection experiments with Chlamydia pecorum and PEDV. TEM examinations of mixed infections with Chlamydia abortus and Chlamydia pecorum revealed aberrant chlamydial inclusions containing reticulate-like, pleomorphic ABs, which were up to 2 microm in diameter. No re-differentiation into elementary bodies (EBs) was detected. In re-infection experiments, co-infected cells produced fewer EBs than monoinfected cells. In the present study we confirm that PEDV co-infection alters the developmental cycle of member species of the family Chlamydiaceae, in a similar manner to other well-described persistence induction methods. Interestingly, this effect appears to be partially species-specific as Chlamydia pecorum appears more sensitive to PEDV co-infection than Chlamydia abortus, as evidenced by TEM and IF observations of a homogenous population of aberrant inclusions in PEDV - Chlamydia pecorum co-infections.

  13. Mixed infections with Chlamydia and porcine epidemic diarrhea virus - a new in vitro model of chlamydial persistence

    Directory of Open Access Journals (Sweden)

    Kaiser Carmen

    2010-07-01

    Full Text Available Abstract Background Chlamydiae induce persistent infections, which have been associated with a wide range of chronic diseases in humans and animals. Mixed infections with Chlamydia and porcine epidemic diarrhea virus (PEDV may result in generation of persistent chlamydial infections. To test this hypothesis, an in vitro model of dual infection with cell culture-adapted PEDV and Chlamydia abortus or Chlamydia pecorum in Vero cells was established. Results Infected cultures were investigated by immunofluorescence (IF, transmission electron microscopy (TEM and re-infection experiments. By IF, Chlamydia-infected cells showed normal inclusions after 39 hpi. Dual infections with Chlamydia abortus revealed a heterogenous mix of inclusion types including small inclusions consisting of aberrant bodies (ABs, medium-sized inclusions consisting of ABs and reticulate bodies and normal inclusions. Only aberrant inclusions were observable in dual infection experiments with Chlamydia pecorum and PEDV. TEM examinations of mixed infections with Chlamydia abortus and Chlamydia pecorum revealed aberrant chlamydial inclusions containing reticulate-like, pleomorphic ABs, which were up to 2 μm in diameter. No re-differentiation into elementary bodies (EBs was detected. In re-infection experiments, co-infected cells produced fewer EBs than monoinfected cells. Conclusions In the present study we confirm that PEDV co-infection alters the developmental cycle of member species of the family Chlamydiaceae, in a similar manner to other well-described persistence induction methods. Interestingly, this effect appears to be partially species-specific as Chlamydia pecorum appears more sensitive to PEDV co-infection than Chlamydia abortus, as evidenced by TEM and IF observations of a homogenous population of aberrant inclusions in PEDV - Chlamydia pecorum co-infections.

  14. Uptake and persistence of pesticides in plants: measurements and model estimates for imidacloprid after foliar and soil application.

    Science.gov (United States)

    Juraske, Ronnie; Castells, Francesc; Vijay, Ashwin; Muñoz, Pere; Antón, Assumpció

    2009-06-15

    The uptake and persistence behaviour of the insecticide imidacloprid in tomato plants treated by (i) foliar spray application and (ii) soil irrigation was studied using two plant uptake models. In addition to a pesticide deposition model, a dynamic root uptake and translocation model was developed, and both models predict residual concentrations of pesticides in or on fruits. The model results were experimentally validated. The fraction of imidacloprid ingested by the human population is on average 10(-2) to 10(-6), depending on the time between pesticide application and ingestion, the processing step, and the application method. Model and experimentally derived intake fractions deviated by less than a factor of 2 for both application techniques. Total imidacloprid residues were up to five times higher in plants treated by foliar spray application than by soil irrigation. However, peeling tomatoes treated by spray application reduces the human intake fraction by up to three orders of magnitude. Model calculations suggest that drip-irrigation in a closed hydroponic system minimizes worker and consumer exposure to pesticides and prevents runoff of pesticide by spray drift and leaching into the environment.

  15. Geohazard monitoring and modelling using Persistent Scatterer Interferometry in the framework of the European project Terrafirma

    Science.gov (United States)

    Cooksley, Geraint; Arnaud, Alain; Banwell, Marie-Josée

    2013-04-01

    Increasingly, geohazard risk managers are looking to satellite observations as a promising option for supporting their risk management and mitigation strategies. The Terrafirma project, aimed at supporting civil protection agencies, local authorities in charge of risk assessment and mitigation is a pan-European ground motion information service funded by the European Space Agency's Global Monitoring for Environment and Security initiative. Over 100 services were delivered to organizations over the last ten years. Terrafirma promotes the use of Synthetic Aperture Radar Interferometry (InSAR) and Persistent Scatterer InSAR (PSI) within three thematic areas for terrain motion analysis: Tectonics, Flooding and Hydrogeology (ground water, landslides and inactive mines), as well as the innovative Wide Area mapping service, aimed at measuring land deformation over very large areas. Terrafirma's thematic services are based on advanced satellite interferometry products; however they exploit additional data sources, including non-EO, coupled with expert interpretation specific to each thematic line. Based on the combination of satellite-derived ground-motion information products with expert motion interpretation, a portfolio of services addressing geo-hazard land motion issues was made available to users. Although not a thematic in itself, the Wide Area mapping product constitutes the fourth quarter of the Terrafirma activities. The wide area processing chain is nearly fully automatic and requires only a little operator interaction. The service offers an operational PSI processing for wide-area mapping with mm accuracy of ground-deformation measurement at a scale of 1:250,000 (i.e. one cm in the map corresponds to 2.5 Km on the ground) on a country or continent level. The WAP was demonstrated using stripmap ERS data however it is foreseen to be a standard for the upcoming Sentinel-1 mission that will be operated in Terrain Observation by Progressive Scan (TOPS) mode. Within

  16. Detecting and modeling persistent self-potential anomalies from underground nuclear explosions at the Nevada Test Site

    International Nuclear Information System (INIS)

    McKague, H.L.; Kansa, E.; Kasameyer, P.W.

    1992-01-01

    Self-potential anomalies are naturally occurring, nearly stationary electric fields that are detected by measuring the potential difference between two points on (or in) the ground. SP anomalies arise from a number of causes: principally electrochemical reactions, and heat and fluid flows. SP is routinely used to locate mineral deposits, geothermal systems, and zones of seepage. This paper is a progress report on our work toward detecting explosion-related SP signals at the Nevada Test Site (NTS) and in understanding the physics of these anomalies that persist and continue changing over periods of time that range from months to years. As background, we also include a brief description of how SP signals arise, and we mention their use in other areas such as exploring for geothermal resources and locating seepage through dams. Between the years 1988 and 1991, we surveyed the areas around seven underground nuclear tests for persistent SP anomalies. We not only detected anomalies, but we also found that various phenomena could be contributing to them and that we did not know which of these were actually occurring. We analyzed our new data with existing steady state codes and with a newly developed time-dependent thermal modeling code. Our results with the new code showed that the conductive decay of the thermal pulse from an underground nuclear test could produce many of the observed signals, and that others are probably caused by movement of fluid induced by the explosion. 25 refs

  17. Multicompartmental fate of persistent substances. Comparison of predictions from multi-media box models and a multicompartment chemistry-atmospheric transport model.

    Science.gov (United States)

    Lammel, Gerhard; Klöpffer, Walter; Semeena, V S; Schmidt, Elisabeth; Leip, Adrian

    2007-05-01

    Modelling of the fate of environmental chemicals can be done by relatively simple multi-media box models or using complex atmospheric transport models. It was the aim of this work to compare the results obtained for both types of models using a small set of non-ionic and non-polar or moderately polar organic chemicals, known to be distributed over long distances. Predictions of multimedia exposure models of different types, namely three multimedia mass-balance box models (MBMs), two in the steady state and one in the non-steady state mode, and one non-steady state multicompartment chemistry-atmospheric transport model (MCTM), are compared for the first time. The models used are SimpleBox, Chemrange, the MPI-MBM and the MPI-MCTM. The target parameters addressed are compartmental distributions (i.e. mass fractions in the compartments), overall environmental residence time (i.e. overall persistence and eventually including other final sinks, such as loss to the deep sea) and a measure for the long-range transport potential. These are derived for atrazine, benz-[a]-pyrene, DDT, alpha and gamma-hexachlorocyclohexane, methyl parathion and various modes of substance entry into the model world. Compartmental distributions in steady state were compared. Steady state needed 2-10 years to be established in the MCTM. The highest fraction of the substances in air is predicted by the MCTM. Accordingly, the other models predict longer substance persistence in most cases. The results suggest that temperature affects the compartmental distribution more in the box models, while it is only one among many climate factors acting in the transport model. The representation of final sinks in the models, e.g. burial in the sediment, is key for model-based compartmental distribution and persistence predictions. There is a tendency of MBMs to overestimate substance sinks in air and to underestimate atmospheric transport velocity as a consequence of the neglection of the temporal and spatial

  18. Persistent Monitoring of Urban Infrasound Phenomenology. Report 1: Modeling an Urban Environment for Acoustical Analyses using the 3-D Finite-Difference Time-Domain Program PSTOP3D

    Science.gov (United States)

    2015-08-01

    ER D C TR -1 5- 5 Remote Assessment of Critical Infrastructure Persistent Monitoring of Urban Infrasound Phenomenology Report 1...ERDC TR-15-5 August 2015 Persistent Monitoring of Urban Infrasound Phenomenology Report 1: Modeling an Urban Environment for Acoustical Analyses...From - To) 4. TITLE AND SUBTITLE Persistent Monitoring of Urban Infrasound Phenomenology ; Report 1: Modeling an Urban Environment for

  19. Designing and Explaining the Model of Persistent Customer Loyalty in e-Commerce: A Study in the e-Retailer’s Web Sites

    OpenAIRE

    Mohammadreza Hamidizadeh; Abasali Hajkarimi; Mohammad Javad Naeiji

    2011-01-01

    Abstract While the importance of customer loyalty has been recognized in marketing literature for several decades, the design and explanation of persistent customer loyalty and its antecedents in electronic commerce especially in an e-retailing context have not been addressed. Therefore, the aim of this study is to develop and validate such antecedents of persistent loyalty and to propose a comprehensive model. For this purpose, based on e-commerce and marketing literature, a comprehensive...

  20. Modeling the potential persistence of various ecological systems under CMIP5 future climate and land use scenarios throughout California, USA

    Science.gov (United States)

    Baker, B.; Ferschweiler, K.; Bachelet, D. M.; Sleeter, B. M.

    2016-12-01

    California's geographic location, topographic complexity and latitudinal climatic gradient give rise to great biological and ecological diversity. However, increased land use pressure, altered seasonal weather patterns, and changes in temperature and precipitation regimes are having pronounced effects on ecosystems and the multitude of services they provide for an increasing population. As a result, natural resource managers are faced with formidable challenges to maintain these critical services. The goals of this project were to better understand how projected 21st century climate and land-use change scenarios may alter ecosystem dynamics, the spatial distribution of various vegetation types and land-use patterns, and to provide a coarse scale "triage map" of where land managers may want to concentrate efforts to reduce ecological stress in order to mitigate the potential impacts of a changing climate. We used the MC2 dynamic global vegetation model and the LUCAS state-and-transition simulation model to simulate the potential effects of future climate and land-use change on ecological processes for the state of California. Historical climate data were obtained from the PRISM dataset and nine CMIP5 climate models were run for the RCP 8.5 scenario. Climate projections were combined with a business-as-usual land-use scenario based on local-scale land use histories. For ease of discussion, results from five simulation runs (historic, hot-dry, hot-wet, warm-dry, and warm-wet) are presented. Results showed large changes in the extent of urban and agricultural lands. In addition, several simulated potential vegetation types persisted in situ under all four future scenarios, although alterations in total area, total ecosystem carbon, and forest vigor (NPP/LAI) were noted. As might be expected, the majority of the forested types that persisted occurred on public lands. However, more than 78% of the simulated subtropical mixed forest and 26% of temperate evergreen

  1. Essays on Imperfect Knowledge Economics, Structural Change, and Persistence in the Cointegrated VAR Model

    DEFF Research Database (Denmark)

    Tabor, Morten Nyboe

    2014-01-01

    This dissertation consists of three self-contained articles presented in three separate chapters. The overall aim is to provide a foundation for combining the new theoretical framework of Imperfect Knowledge Economics (IKE) developed by Frydman and Goldberg (2007, 2011) with the econometric...... methodology based on the cointegrated VAR model of Johansen (1996) developed at the University of Copenhagen. In the rst chapter, I consider a simple general IKE asset pricing model and show how internal consistency can be fully incorporated in IKE models in a way that both allows for internal consistency...... compatible with individual rationality and accords individuals' expectations a partly autonomous role in driving aggregate outcomes. Moreover, I show how internal consistency conditions imply that the asset price and the exogenous variables in the model are cointegrated with stochastic cointegration...

  2. Semibiotic Persistence

    Science.gov (United States)

    Prothmann, C.; Zauner, K.-P.

    From observation, we find four different strategies to successfully enable structures to persist over extended periods of time. If functionally relevant features are very large compared to the changes that can be effectuated by entropy, the functional structure itself has a high enough probability to erode only slowly over time. If the functionally relevant features are protected from environmental influence by sacrificial layers that absorb the impinging of the environment, deterioration can be avoided or slowed. Loss of functionality can be delayed, even for complex systems, by keeping alternate options for all required components available. Biological systems also apply information processing to actively counter the impact of entropy by mechanisms such as self-repair. The latter strategy increases the overall persistence of living systems and enables them to maintain a highly complex functional organisation during their lifetime and over generations. In contrast to the other strategies, information processing has only low material overhead. While at present engineered technology is far from achieving the self-repair of evolved systems, the semibiotic combination of biological components with conventionally engineered systems may open a path to long-term persistence of functional devices in harsh environments. We review nature's strategies for persistence, and consider early steps taken in the laboratory to import such capabilities into engineered architectures.

  3. Causes and Implications of Persistent Atmospheric Carbon Dioxide Biases in Earth System Models

    Energy Technology Data Exchange (ETDEWEB)

    Hoffman, Forrest M [ORNL; Randerson, James T. [University of California, Irvine; Arora, Vivek K. [Canadian Centre for Climate Modelling and Analysis, Meteorological Service of Canada; Bao, Qing [State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics; Cadule, Patricia [Institut Pierre Simon Laplace, Laboratoire des Sciences du Climat et de l' Environment; Ji, Duoying [State Key Laboratory of Earth Surface Processes and Resource Ecology, Beijing; Jones, Chris D. [Hadley Centre, U.K. Met Office; Kawamiya, Michio [Japan Agency for Marine-Earth Science and Technology (JAMSTEC); Khatiwala, Samar [Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY; Lindsay, Keith [National Center for Atmospheric Research (NCAR); Obata, Atsushi [Meteorological Research Institute, Japan; Shevliakova, Elena [Princeton University; Six, Katharina D. [Max Planck Institute for Meteorology, Hamburg, Germany; Tjiputra, Jerry F. [Uni Climate, Uni Research; Volodin, Evgeny M. [Institute of Numerical Mathematics, Russian Academy of Science, Moscow; Wu, Tongwen [China Meteorological Administration (CMA), Beijing

    2014-01-01

    The strength of feedbacks between a changing climate and future CO2 concentrations are uncertain and difficult to predict using Earth System Models (ESMs). We analyzed emission-driven simulations--in which atmospheric CO2 levels were computed prognostically--for historical (1850-2005) and future periods (RCP 8.5 for 2006-2100) produced by 15 ESMs for the Fifth Phase of the Coupled Model Intercomparison Project (CMIP5). Comparison of ESM prognostic atmospheric CO2 over the historical period with observations indicated that ESMs, on average, had a small positive bias in predictions of contemporary atmospheric CO2. Weak ocean carbon uptake in many ESMs contributed to this bias, based on comparisons with observations of ocean and atmospheric anthropogenic carbon inventories. We found a significant linear relationship between contemporary atmospheric CO2 biases and future CO2 levels for the multi-model ensemble. We used this relationship to create a contemporary CO2 tuned model (CCTM) estimate of the atmospheric CO2 trajectory for the 21st century. The CCTM yielded CO2 estimates of 600 {plus minus} 14 ppm at 2060 and 947 {plus minus} 35 ppm at 2100, which were 21 ppm and 32 ppm below the multi-model mean during these two time periods. Using this emergent constraint approach, the likely ranges of future atmospheric CO2, CO2-induced radiative forcing, and CO2-induced temperature increases for the RCP 8.5 scenario were considerably narrowed compared to estimates from the full ESM ensemble. Our analysis provided evidence that much of the model-to-model variation in projected CO2 during the 21st century was tied to biases that existed during the observational era, and that model differences in the representation of concentration-carbon feedbacks and other slowly changing carbon cycle processes appear to be the primary driver of this variability. By improving models to more closely match the long-term time series of CO2 from Mauna Loa, our analysis suggests uncertainties in

  4. Minority persistence in agent based model using information and emotional arousal as control variables

    Science.gov (United States)

    Sobkowicz, Pawel

    2013-07-01

    We present detailed analysis of the behavior of an agent based model of opinion formation, using a discrete variant of cusp catastrophe behavior of single agents. The agent opinion about a particular issue is determined by its information about the issue and its emotional arousal. It is possible that for agitated agents the same information would lead to different opinions. This results in a nontrivial individual opinion dynamics. The agents communicate via messages, which allows direct application of the model to ICT based communities. We study the dependence of the composition of an agent society on the range of interactions and the rate of emotional arousal. Despite the minimal number of adjustable parameters, the model reproduces several phenomena observed in real societies, for example nearly perfectly balanced results of some highly contested elections or the fact that minorities seldom perceive themselves to be a minority.

  5. Analyzing Phylogenetic Trees with Timed and Probabilistic Model Checking: The Lactose Persistence Case Study

    Directory of Open Access Journals (Sweden)

    Requeno José Ignacio

    2014-12-01

    Full Text Available Model checking is a generic verification technique that allows the phylogeneticist to focus on models and specifications instead of on implementation issues. Phylogenetic trees are considered as transition systems over which we interrogate phylogenetic questions written as formulas of temporal logic. Nonetheless, standard logics become insufficient for certain practices of phylogenetic analysis since they do not allow the inclusion of explicit time and probabilities. The aim of this paper is to extend the application of model checking techniques beyond qualitative phylogenetic properties and adapt the existing logical extensions and tools to the field of phylogeny. The introduction of time and probabilities in phylogenetic specifications is motivated by the study of a real example: the analysis of the ratio of lactose intolerance in some populations and the date of appearance of this phenotype.

  6. Decrease of d -wave pairing strength in spite of the persistence of magnetic excitations in the overdoped Hubbard model

    International Nuclear Information System (INIS)

    Huang, Edwin W.; Scalapino, Douglas J.; Maier, Thomas A.; Moritz, Brian; Devereaux, Thomas P.

    2017-01-01

    Evidence for the presence of high-energy magnetic excitations in overdoped La 2–x Sr x CuO 4 (LSCO) has raised questions regarding the role of spin fluctuations in the pairing mechanism. If they remain present in overdoped LSCO, why does T c decrease in this doping regime? Here, using results for the dynamic spin susceptibility Imχ(q,ω) obtained from a determinantal quantum Monte Carlo calculation for the Hubbard model, we address this question. We find that while high-energy magnetic excitations persist in the overdoped regime, they lack the momentum to scatter pairs between the antinodal regions. Finally, it is the decrease in the spectral weight at large momentum transfer, not observed by resonant inelastic x-ray scattering, which leads to a reduction in the d-wave spin-fluctuation pairing strength.

  7. Persistent Coxiella burnetii infection in mice overexpressing IL-10: an efficient model for chronic Q fever pathogenesis.

    Directory of Open Access Journals (Sweden)

    Soraya Meghari

    2008-02-01

    Full Text Available Interleukin (IL-10 increases host susceptibility to microorganisms and is involved in intracellular persistence of bacterial pathogens. IL-10 is associated with chronic Q fever, an infectious disease due to the intracellular bacterium Coxiella burnetii. Nevertheless, accurate animal models of chronic C. burnetii infection are lacking. Transgenic mice constitutively expressing IL-10 in macrophages were infected with C. burnetti by intraperitoneal and intratracheal routes and infection was analyzed through real-time PCR and antibody production. Transgenic mice exhibited sustained tissue infection and strong antibody response in contrast to wild-type mice; thus, bacterial persistence was IL-10-dependent as in chronic Q fever. The number of granulomas was low in spleen and liver of transgenic mice infected through the intraperitoneal route, as in patients with chronic Q fever. Macrophages from transgenic mice were unable to kill C. burnetii. C. burnetii-stimulated macrophages were characterized by non-microbicidal transcriptional program consisting of increased expression of arginase-1, mannose receptor, and Ym1/2, in contrast to wild-type macrophages in which expression of inducible NO synthase and inflammatory cytokines was increased. In vivo results emphasized macrophage data. In spleen and liver of transgenic mice infected with C. burnetii by the intraperitoneal route, the expression of arginase-1 was increased while microbicidal pathway consisting of IL-12p40, IL-23p19, and inducible NO synthase was depressed. The overexpression of IL-10 in macrophages prevents anti-infectious competence of host, including the ability to mount granulomatous response and microbicidal pathway in tissues. To our knowledge, this is the first efficient model for chronic Q fever pathogenesis.

  8. Linearity Testing in Time-Varying Smooth Transition Autoregressive Models under Unknown Degree of Persistency

    DEFF Research Database (Denmark)

    Sandberg, Rickard; Kruse, Robinson

    Building upon the work of Vogelsang (1998) and Harvey and Leybourne (2007) we derive tests that are invariant to the order of integration when the null hypothesis of linearity is tested in time-varying smooth transition models. As heteroscedasticity may lead to spurious rejections of the null...

  9. Accountability in Training Transfer: Adapting Schlenker's Model of Responsibility to a Persistent but Solvable Problem

    Science.gov (United States)

    Burke, Lisa A.; Saks, Alan M.

    2009-01-01

    Decades have been spent studying training transfer in organizational environments in recognition of a transfer problem in organizations. Theoretical models of various antecedents, empirical studies of transfer interventions, and studies of best practices have all been advanced to address this continued problem. Yet a solution may not be so…

  10. Prediction vs. reality: Can a PVA model predict population persistence 13 years later?

    Czech Academy of Sciences Publication Activity Database

    Schödelbauerová, Iva; Tremblay, R. L.; Kindlmann, Pavel

    2010-01-01

    Roč. 19, č. 3 (2010), s. 637-650 ISSN 0960-3115 R&D Projects: GA MŠk LC06073 Institutional research plan: CEZ:AV0Z60870520 Keywords : Lepanthes rubripetala * Matrix models * Orchids * Transition matrix Subject RIV: EH - Ecology, Behaviour Impact factor: 2.146, year: 2010

  11. Interpretation and extrapolation of ecological responses in model ecosystems stressed with non-persistent insecticides

    NARCIS (Netherlands)

    Wijngaarden, van R.P.A.

    2006-01-01

    This thesis aims to contribute to the discussion concerning whether micro- and mesocosm studies can serve as adequate models for robust risk assessment of pesticides. For this purpose, results from freshwater micro- and mesocosm experiments conducted under different experimental conditions are

  12. A conceptual model for the growth, persistence, and blooming behavior of the benthic mat-forming diatom Didymosphenia geminata (Invited)

    Science.gov (United States)

    Cullis, J. D.; Gillis, C.; Bothwell, M.; Kilroy, C.; Packman, A. I.; Hassan, M. A.

    2010-12-01

    The nuisance diatom Didymosphenia geminata (didymo) presents an ecological paradox. How can this benthic algae produce such large amounts of biomass in cold, fast flowing, low nutrient streams? The aim of this paper is to present a conceptual model for the growth, persistence, and blooming behavior of this benthic mat-forming diatom that may help to explain this paradox. The conceptual model highlights the importance of distinguishing between mat thickness and cell growth. It presents evidence gathered from a range of existing studies around the world to support the proposed relationship between growth and light, nutrients and temperature as well as the importance of flood events and bed disturbance in mat removal. It is anticipated that this conceptual model will not only help in identifying the key controlling variables and set a framework for future studies but also support the future management of this nuisance algae. Summary of the conceptual model for didymo growth showing the proposed relationships for the growth of cells and mats with nutrients, radiation and water temperature and the dependence of removal on bed shear stress and the potential for physical bed disturbance.

  13. Climate change and plant distribution: local models predict high-elevation persistence

    DEFF Research Database (Denmark)

    Randin, Christophe F.; Engler, Robin; Normand, Signe

    2009-01-01

    Mountain ecosystems will likely be affected by global warming during the 21st century, with substantial biodiversity loss predicted by species distribution models (SDMs). Depending on the geographic extent, elevation range, and spatial resolution of data used in making these models, different rates...... of habitat loss have been predicted, with associated risk of species extinction. Few coordinated across-scale comparisons have been made using data of different resolutions and geographic extents. Here, we assess whether climate change-induced habitat losses predicted at the European scale (10 × 10' grid...... in the area. Proportion of habitat loss depends on climate change scenario and study area. We find good agreement between the mismatch in predictions between scales and the fine-grain elevation range within 10 × 10' cells. The greatest prediction discrepancy for alpine species occurs in the area...

  14. Design issues of time-based phenomena and the notion of a persistent model

    DEFF Research Database (Denmark)

    Peters, Brady

    2012-01-01

    This chapter reflects on how sound can become part the architectural design process. Sound is a complex phenomenon that traditional architectural drawing tools do not capture well. Parametric tools allow for the encoding of relationships between material, geometry, and acoustic performance...... in a digital model. Computational simulation tools can give visual and aural feedback on how designs perform. These tools give architects the ability to contemplate the sound of architectural propositions. Different sounds, sound positions, and listener positions can be tested, as can different geometric...... and material configurations. Using these tools architects can design for sound. Sound should be a part of the architectural design process and in order for it to be a useful design parameter; it must be able to be considered in the digital modeling environment. We form a spatial impression of our surroundings...

  15. Hepatitis C Virus Evasion of Adaptive Immune Responses- A Model for Viral Persistence

    OpenAIRE

    Burke, Kelly P.; Cox, Andrea L.

    2010-01-01

    Hepatitis C virus (HCV) infects over 170 million people worldwide and is a leading cause of cirrhosis and hepatocellular carcinoma. Approximately 20% of those acutely infected clear the infection, whereas the remaining 80% progress to chronic infection. Hepatitis C thus provides a model in which successful and unsuccessful responses can be compared to better understand the human response to viral infection. Our laboratory studies the strategies by which HCV evades the adaptive immune response...

  16. Bimetallic Schiff base complexes: models for conjugated shape-persistent metallopolymers.

    Science.gov (United States)

    Leung, Alfred C W; Hui, Joseph K-H; Chong, Jonathan H; MacLachlan, Mark J

    2009-07-14

    New Schiff base ligands with two metal binding sites have been prepared. Copper and zinc complexes of the ligands, which serve as models for rigid, conjugated metallopolymers, were synthesized and characterized. The copper complexes display only weak intramolecular antiferromagnetic interactions, suggesting that the polymer structure is not useful for developing magnetic materials. Preliminary investigations of the novel polymers, including the preparation of a conjugated zinc-containing polymer, are reported.

  17. Population persistence of stream fish in response to environmental change: integrating data and models across space

    Science.gov (United States)

    Letcher, B. H.; Schueller, P.; Bassar, R.; Coombs, J.; Rosner, A.; Sakrejda, K.; Kanno, Y.; Whiteley, A.; Nislow, K. H.

    2013-12-01

    For stream fishes, environmental variation is a key driver of individual body growth/movement/survival and, by extension, population dynamics. Identifying how stream fish respond to environmental variation can help clarify mechanisms responsible for population dynamics and can help provide tools to forecast relative resilience of populations across space. Forecasting dynamics across space is challenging, however, because it can be difficult to conduct enough studies with enough intensity to fully characterize broad-scale population response to environmental change. We have adopted a multi-scale approach, using detailed individual-based studies and analyses (integral projection matrix) to determine sensitivities of population growth to environmental variation combined with broad spatial data and analyses (occupancy and abundance models) to estimate patterns of population response across space. Population growth of brook trout was most sensitive to stream flow in the spring and winter, most sensitive to stream temperature in the fall and sensitive to both flow and temperature in the summer. High flow in the spring and winter had negative effects on population growth while high temperature had a negative effect in the fall. Flow had no effect when it was cold, but a positive effect when it was warm in the summer. Combined with occupancy and abundance models, these data give insight into the spatial structure of resilient populations and can help guide prioritization of management actions.

  18. Serotonin contributes to high pulmonary vascular tone in a sheep model of persistent pulmonary hypertension of the newborn

    Science.gov (United States)

    Gien, Jason; Roe, Gates; Isenberg, Nicole; Kailey, Jenai; Abman, Steven H.

    2013-01-01

    Although past studies demonstrate that altered serotonin (5-HT) signaling is present in adults with idiopathic pulmonary arterial hypertension, whether serotonin contributes to the pathogenesis of persistent pulmonary hypertension of the newborn (PPHN) is unknown. We hypothesized that 5-HT contributes to increased pulmonary vascular resistance (PVR) in a sheep model of PPHN and that selective 5-HT reuptake inhibitor (SSRI) treatment increases PVR in this model. We studied the hemodynamic effects of 5-HT, ketanserin (5-HT2A receptor antagonist), and sertraline, an SSRI, on pulmonary hemodynamics of the late gestation fetal sheep with PPHN caused by prolonged constriction of the ductus arteriosis. Brief intrapulmonary infusions of 5-HT increased PVR from 1.0 ± 0.07 (baseline) to 1.4 ± 0.22 mmHg/ml per minute of treatment (P pulmonary artery endothelial cells from fetal sheep with PPHN exhibited increased expression of tryptophan hydroxylase 1 and 5-HT production by twofold and 56%, respectively. Compared with controls, 5-HT2A R expression was increased in lung homogenates and pulmonary artery smooth muscle cell lysates by 35% and 32%, respectively. We concluded that increased 5-HT contributes to high PVR in experimental PPHN through activation of the 5-HT2A receptor and that SSRI infusion further increases PVR in this model. PMID:23605003

  19. The potent bactericidal activity of streptomycin in the guinea pig model of tuberculosis ceases due to the presence of persisters.

    Science.gov (United States)

    Ahmad, Zahoor; Pinn, Michael L; Nuermberger, Eric L; Peloquin, Charles A; Grosset, Jacques H; Karakousis, Petros C

    2010-10-01

    The biphasic kill curve of isoniazid against Mycobacterium tuberculosis in guinea pigs is due to the presence of persisters rather than selection of isoniazid-resistant mutants. To determine whether this phenomenon is common to other bactericidal drugs, we studied the activity of streptomycin and its ability to select for streptomycin-resistant mutants in the guinea pig model of tuberculosis. Pharmacokinetic studies were performed to establish the human-equivalent dose of streptomycin. Guinea pigs were aerosol-infected with M. tuberculosis and 2 weeks later streptomycin was given for 5 days/week via intramuscular injection. Bactericidal activity was assessed by homogenizing and plating lungs for cfu until 10 weeks of treatment. At each timepoint, cfu were isolated, suspended in normal saline and re-plated on plates containing 0.5, 1.0, 2.0 or 10.0 mg/L streptomycin. The human-equivalent dose of streptomycin was determined to be 70 mg/kg. Streptomycin showed potent activity during the first 14 days of treatment, rescuing all animals from acute tuberculosis-related death and reducing lung cfu by ∼4 log(10). However, streptomycin activity was dramatically reduced thereafter, as lung cfu declined by only ∼1 log(10) over the next 56 days of treatment. Although streptomycin-resistant mutants were detectable, their frequency of isolation was identical at treatment initiation and after 70 days of treatment. The reduced activity of streptomycin during the second phase of monotherapy is not associated with the selection of streptomycin-resistant mutants but, rather, with the presence of phenotypically tolerant 'persisters'.

  20. Persistent Penumbra in a Rabbit Stroke Model: Incidence and Histologic Characteristics

    Directory of Open Access Journals (Sweden)

    Leah J. Hennings

    2011-01-01

    Full Text Available Duration and extent of penumbra determine the window and brain volume in which interventions may save injured tissue after stroke. Understanding the penumbra in animals is necessary in order to design models that translate to effective clinical therapies. New Zealand white rabbits were embolized with aged autologous clot (n=23 or insoluble microspheres (n=21. To examine effects of treatment on penumbra, sphere-stroked animals were treated with 3 μm microbubbles plus ultrasound (n=19. Rabbits were euthanized at 4 or 24 hr. Infarct volume was measured following triphenyltetrazolium chloride (TTC staining of brain sections. Penumbra was visualized using immunostaining of pimonidazole injected fifteen minutes prior to euthanasia. Potentially reversible penumbra was present in 14.3% stroked rabbits at 4 hours and 15.7% at 24 hours after embolic stroke and represented up to 35% of total lost tissue. Intervention at up to 24 hours may benefit a significant patient population.

  1. Hepatitis C virus evasion of adaptive immune responses: a model for viral persistence.

    Science.gov (United States)

    Burke, Kelly P; Cox, Andrea L

    2010-07-01

    Hepatitis C virus (HCV) infects over 170 million people worldwide and is a leading cause of cirrhosis and hepatocellular carcinoma. Approximately 20% [corrected] of those acutely infected clear the infection, whereas the remaining 80% [corrected] progress to chronic infection. Hepatitis C thus provides a model in which successful and unsuccessful responses can be compared to better understand the human response to viral infection. Our laboratory studies the strategies by which HCV evades the adaptive immune response. This review describes the impact of viral mutation on T cell recognition, the role of cell surface inhibitory receptors in recognition of HCV, and the development of antibodies that neutralize HCV infection. Understanding what constitutes an effective immune response in the control of HCV may enable the development of prophylactic and therapeutic vaccines for HCV and other chronic viral infections.

  2. Persistence and Evolutions of the Rentier State Model in Gulf Countries

    International Nuclear Information System (INIS)

    Ozyavuz, Anais; Schmid, Dorothee

    2015-04-01

    A general economic model of understanding Middle Eastern states was elaborated by political scientists around the 1980's, based on the concept of rent. Rent derived from the exploitations and sales of natural resources (mainly crude-oil and gas reserves for the Middle-East area) became a new factor of wealth around which the economic model as much as the governance of energy-rich countries was reorganized. The particular case of GCC's countries as rentier state has been at the cornerstone of this concept since they own the most important share of energy resources in the world. Despite bringing high revenues to resource-abundant countries, rent clearly has a bad reputation, implying a system of 'allocative state' vs. 'productive state'. After four decades of the concept's circulation, the historicity of the rentier state theory clearly requires discussion. This paper will first deal with the emergence of the concept of rent in Gulf countries, and will study in which extend GCC member states have undertaken reforms and changes for depending less on oil-wealth and for reaching a more diversified economy. Despite their efforts and achievements - both endogenous as exogenous factors - are still inhibiting the development processes in each country. The improvements of the economy and the governance in those 6 countries have been - and will be - important not only for the concerned countries but also for the development and especially the stability of the Middle-East area. This last concern is definitely the main issue of last months for the area, being in the chaos since the emergence of a new regional player, the terrorist group Daesh. (author)

  3. Basic Diagnosis and Prediction of Persistent Contrail Occurrence using High-resolution Numerical Weather Analyses/Forecasts and Logistic Regression. Part II: Evaluation of Sample Models

    Science.gov (United States)

    Duda, David P.; Minnis, Patrick

    2009-01-01

    Previous studies have shown that probabilistic forecasting may be a useful method for predicting persistent contrail formation. A probabilistic forecast to accurately predict contrail formation over the contiguous United States (CONUS) is created by using meteorological data based on hourly meteorological analyses from the Advanced Regional Prediction System (ARPS) and from the Rapid Update Cycle (RUC) as well as GOES water vapor channel measurements, combined with surface and satellite observations of contrails. Two groups of logistic models were created. The first group of models (SURFACE models) is based on surface-based contrail observations supplemented with satellite observations of contrail occurrence. The second group of models (OUTBREAK models) is derived from a selected subgroup of satellite-based observations of widespread persistent contrails. The mean accuracies for both the SURFACE and OUTBREAK models typically exceeded 75 percent when based on the RUC or ARPS analysis data, but decreased when the logistic models were derived from ARPS forecast data.

  4. Persistence of DNA studied in different ex vivo and in vivo rat models simulating the human gut situation

    DEFF Research Database (Denmark)

    Wilcks, Andrea; van Hoek, A.H.A.M.; Joosten, R.G.

    2004-01-01

    This study aimed to evaluate the possibility of DNA sequences from genetically modified plants to persist in the gastrointestinal (GI) tract. PCR analysis and transformation assays were used to study DNA persistence and integrity in various ex vivo and in vivo systems using gnotobiotic rats. DNA...

  5. The role of soil organic carbon in the global cycling of persistent organic pollutants (POPs): interpreting and modelling field data.

    Science.gov (United States)

    Sweetman, Andrew J; Valle, Matteo Dalla; Prevedouros, Konstantinos; Jones, Kevin C

    2005-08-01

    Soil is an important global reservoir for persistent organic pollutants (POPs). The interaction between air (which often receives the majority of emissions) and soil plays a key role in the long term environmental cycling and fate of these chemicals. Soil surveys have been carried out to try and estimate regional and global distribution/inventory of POPs. A correlation between soil POPs concentration and soil organic carbon (SOC) has been observed in background soils [Meijer et al., 2003. Global distribution and budget of PCBs and HCB in background surface soils: implications for sources and environmental processes. Environ. Sci. Technol., 37, 667], provoking discussion about whether POPs will approach steady-state (or equilibrium) between air and SOC, on a global scale. This manuscript investigates this relationship and in particular how soil concentrations can be influenced by factors such as temperature, SOC content and physicochemical properties. A simple two box model designed to investigate parameters that are likely to affect air-soil exchange revealed that more volatile chemicals such as HCB are likely to achieve steady-state conditions between air and soil relatively quickly whilst relatively involatile chemicals, such as heavy PCBs, may take considerably longer and other compounds (e.g. OCDD) may never achieve it. These model calculations provide an insight into which fate processes (e.g. volatilisation or degradation) may control a chemicals fate in the terrestrial environment. A different modelling exercise was used to explore the complex interaction of environmental parameters, representative of 'real world' conditions to study their potential influence on POPs cycling at the European scale. Results from the model suggested that compound degradation rates in soil (linked to SOC content), temperature, vegetation cover and ecosystem C turnover are all likely to significantly influence POP air-soil exchange and fate.

  6. Ensuring consistency and persistence to the Quality Information Model - The role of the GeoViQua Broker

    Science.gov (United States)

    Bigagli, Lorenzo; Papeschi, Fabrizio; Nativi, Stefano; Bastin, Lucy; Masó, Joan

    2013-04-01

    a few products are annotated with their PID; recent studies show that on a total of about 100000 Clearinghouse products, only 37 have the Product Identifier. Furthermore the association should be persistent within the GeoViQua scope. GeoViQua architecture is built on the brokering approach successfully experimented within the EuroGEOSS project and realized by the GEO DAB (Discovery and Access Broker). Part of the GEOSS Common Infrastructure (GCI), the GEO DAB allows for harmonization and distribution in a transparent way for both users and data providers. This way, GeoViQua can effectively complement and extend the GEO DAB obtaining a Quality-augmentation broker (GeoViQua Broker) which plays a central role in ensuring the consistency of the Producer and User quality models. This work is focused on the typical use case in which the GeoViQua Broker performs data discovery from different data providers, and then integrates in the Quality Information Model the producer quality report with the feedback given by users. In particular, this work highlights the problems faced by the GeoViQua Broker and the techniques adopted to ensure consistency and persistency also for quality reports whose target products are not annotated with a PID. The research leading to these results has received funding from the European Community's Seventh Framework Programme (FP7/2007-2013) under Grant Agreement n° 265178.

  7. Modest Amounts of Voluntary Exercise Reduce Pain- and Stress-Related Outcomes in a Rat Model of Persistent Hind Limb Inflammation.

    Science.gov (United States)

    Pitcher, Mark H; Tarum, Farid; Rauf, Imran Z; Low, Lucie A; Bushnell, Catherine

    2017-06-01

    Aerobic exercise improves outcomes in a variety of chronic health conditions, yet the support for exercise-induced effects on chronic pain in humans is mixed. Although many rodent studies have examined the effects of exercise on persistent hypersensitivity, the most used forced exercise paradigms that are known to be highly stressful. Because stress can also produce analgesic effects, we studied how voluntary exercise, known to reduce stress in healthy subjects, alters hypersensitivity, stress, and swelling in a rat model of persistent hind paw inflammation. Our data indicate that voluntary exercise rapidly and effectively reduces hypersensitivity as well as stress-related outcomes without altering swelling. Moreover, the level of exercise is unrelated to the analgesic and stress-reducing effects, suggesting that even modest amounts of exercise may impart significant benefit in persistent inflammatory pain states. Modest levels of voluntary exercise reduce pain- and stress-related outcomes in a rat model of persistent inflammatory pain, independently of the amount of exercise. As such, consistent, self-regulated activity levels may be more relevant to health improvement in persistent pain states than standardized exercise goals. Published by Elsevier Inc.

  8. The dose of HBV genome contained plasmid has a great impact on HBV persistence in hydrodynamic injection mouse model.

    Science.gov (United States)

    Li, Lei; Li, Sheng; Zhou, Yun; Yang, Lu; Zhou, Di; Yang, Yan; Lu, Mengji; Yang, Dongliang; Song, Jingjiao

    2017-10-25

    Hydrodynamic injection (HI) of hepatitis B virus (HBV) mouse model is an useful tool for HBV related research in vivo. However, only 40% of C57/BL6 mice injected with 10 μg HBV genome contained plasmid (pAAV-HBV1.2), serum HBsAg more than 6 months and none of the BALB/c mice injected with 10 μg pAAV-HBV1.2 plasmid DNA, serum HBsAg positive more than 4 weeks in the previous study. In this study, C57/BL6 and BALB/c mice were hydrodynamic injected with different doses of pAAV-HBV1.2 plasmid DNA. HBV related serum markers were detected by ELISA. ALT levels in the serum were measured using full automated biochemistry analyzer. HBcAg positive cells in the liver were detected by immunohistochemical staining. The mRNA levels of IRF3, ISGs including ISG15, OAS, PKR and immune factors including IFNγ, TNFα, TGFβ, IL-6, IL-10, PDL1 in liver of the mice were quantified by qRT-PCR. The results showed that the mice injected with 100 μg high-concentration or 1 μg low-concentration of pAAV-HBV1.2 plasmid DNA did not excert dominant influence on HBV persistence. In contrast, injection of 5 μg intermediate-dose of pAAV-HBV1.2 plasmid DNA led to significant prolonged HBsAg expression and HBV persistence in both C57/BL6 (80% of the mice with HBsAg positive more than 6 months) and BALB/c (60% of the mice with HBsAg positive more than 3 months) mice. IFNγ was significant up-regulated in liver of the mice injected with 1 μg or 100 μg pAAV-HBV1.2 plasmid DNA. TNFα was up-regulated significantly in liver of the mice injected with 100 μg pAAV-HBV1.2 plasmid DNA. Moreover, PDL1 was significant up-regulated in liver of the mice injected with 5 μg pAAV-HBV1.2 plasmid DNA. In this paper we demonstrated that, in the HBV HI mouse model, the concentration of injected pAAV-HBV1.2 plasmid DNA contributes to the diverse kinetics of HBsAg and HBeAg in the serum as well as HBcAg expression level in the liver, which then determined the HBV persisternce, while the antiviral

  9. Introduction: Persistent Modelling

    DEFF Research Database (Denmark)

    Ayres, Phil

    2012-01-01

    of this relationship is becoming increasingly variegated. This is apparent in three principle areas; the duration of active influence that representation can hold in relation to the represented; the means, methods and media through which representations are constructed and used; what it is that is being represented....

  10. Effects of a water extract of Lepidium meyenii root in different models of persistent pain in rats.

    Science.gov (United States)

    Tenci, Barbara; Di Cesare Mannelli, Lorenzo; Maresca, Mario; Micheli, Laura; Pieraccini, Giuseppe; Mulinacci, Nadia; Ghelardini, Carla

    2017-10-26

    Lepidium meyenii (Walp.), commonly called maca, is an Andean crop belonging to the Brassicaceae family. Maca hypocotils are habitually consumed as customary food as well as traditional remedies for pathological conditions such as infertility. Moreover, the characterization of maca extracts revealed the presence of compounds that are able to modulate the nervous system. Aimed to evaluate the efficacy of L. meyenii in persistent pain, the present study analyzed the effects of a commercial root extract from maca in different animal models reproducing the most common causes of chronic painful pathologies. A qualitative characterization of this commercial extract by high performance liquid chromatography-mass spectrometry and tandem mass spectrometry analyses allowed us to confirm the presence of some macamides known as bioactive constituents of this root and the absence of the main aromatic glucosinolates. The acute oral administration of maca extract is able to reduce mechanical hypersensitivity and postural unbalance induced by the intra-articular injection of monoiodoacetate and the chronic-constriction injury of the sciatic nerve. Furthermore, L. meyenii extract reverts pain threshold alterations evoked by oxaliplatin and paclitaxel. A good safety profile in mice and rats was shown. In conclusion, the present maca extract could be considered as a therapeutic opportunity to relieve articular and neuropathic pain.

  11. Persistent deficits in hippocampal synaptic plasticity accompany losses of hippocampus-dependent memory in a rodent model of psychosis

    Directory of Open Access Journals (Sweden)

    Valentina eWiescholleck

    2013-03-01

    Full Text Available Irreversible N-methyl-D-aspartate receptor (NMDAR antagonism is known to provoke symptoms of psychosis and schizophrenia in healthy humans. NMDAR hypofunction is believed to play a central role in the pathophysiology of both disorders and in an animal model of psychosis, that is based on irreversible antagonism of NMDARs, pronounced deficits in hippocampal synaptic plasticity have been reported shortly after antagonist treatment. Here, we examined the long-term consequences for long-term potentiation (LTP of a single acute treatment with an irreversible antagonist and investigated whether deficits are associated with memory impairments.The ability to express long-term potentiation (LTP at the perforant pathway – dentate gyrus synapse, as well as object recognition memory was assessed 1, 2, 3 and 4 weeks after a single -treatment of the antagonist, MK801. Here, LTP in freely behaving rats was significantly impaired at all time-points compared to control LTP before treatment. Object recognition memory was also significantly poorer in MK801-treated compared to vehicle-treated animals for several weeks after treatment. Histological analysis revealed no changes in brain tissue.Taken together, these data support that acute treatment with an irreversible NMDAR antagonist persistently impairs hippocampal functioning on behavioral, as well as synaptic levels. The long-term deficits in synaptic plasticity may underlie the cognitive impairments that are associated with schizophrenia-spectrum disorders.

  12. A Stochastic Model to Study Rift Valley Fever Persistence with Different Seasonal Patterns of Vector Abundance: New Insights on the Endemicity in the Tropical Island of Mayotte.

    Directory of Open Access Journals (Sweden)

    Lisa Cavalerie

    Full Text Available Rift Valley fever (RVF is a zoonotic vector-borne disease causing abortion storms in cattle and human epidemics in Africa. Our aim was to evaluate RVF persistence in a seasonal and isolated population and to apply it to Mayotte Island (Indian Ocean, where the virus was still silently circulating four years after its last known introduction in 2007. We proposed a stochastic model to estimate RVF persistence over several years and under four seasonal patterns of vector abundance. Firstly, the model predicted a wide range of virus spread patterns, from obligate persistence in a constant or tropical environment (without needing vertical transmission or reintroduction to frequent extinctions in a drier climate. We then identified for each scenario of seasonality the parameters that most influenced prediction variations. Persistence was sensitive to vector lifespan and biting rate in a tropical climate, and to host viraemia duration and vector lifespan in a drier climate. The first epizootic peak was primarily sensitive to viraemia duration and thus likely to be controlled by vaccination, whereas subsequent peaks were sensitive to vector lifespan and biting rate in a tropical climate, and to host birth rate and viraemia duration in arid climates. Finally, we parameterized the model according to Mayotte known environment. Mosquito captures estimated the abundance of eight potential RVF vectors. Review of RVF competence studies on these species allowed adjusting transmission probabilities per bite. Ruminant serological data since 2004 and three new cross-sectional seroprevalence studies are presented. Transmission rates had to be divided by more than five to best fit observed data. Five years after introduction, RVF persisted in more than 10% of the simulations, even under this scenario of low transmission. Hence, active surveillance must be maintained to better understand the risk related to RVF persistence and to prevent new introductions.

  13. Persistence of Adult Undergraduates on a Traditionally-Oriented University Campus: Does Donaldson and Graham's Model of College Outcomes for Adult Students Still Apply?

    Science.gov (United States)

    Samuels, Wendy; Beach, Andrea L.; Palmer, Louann Bierlein

    2012-01-01

    The purpose of this study was to explore the social and academic experiences of non-traditional students pursuing a bachelor's degree at a traditionally-oriented residential university and how these experiences promote or impede their persistence to graduation. The study explored components of Donaldson and Graham's Model of College Outcomes for…

  14. A Modified Model of College Student Persistence: Exploring the Relationship between Astin's Theory of Involvement and Tinto's Theory of Student Departure.

    Science.gov (United States)

    Milem, Jeffrey F.; Berger, Joseph B.

    1997-01-01

    Provides insight into first-year undergraduate persistence by using behavioral measures--based on Alexander Astin's theory of involvement--to further understanding of Tinto's theory of student departure. Findings support the use of an integrated model in which student behaviors and perceptions interact to influence the development of academic and…

  15. Epigenetic regulation of persistent pain

    Science.gov (United States)

    Bai, Guang; Ren, Ke; Dubner, Ronald

    2014-01-01

    Persistent or chronic pain is tightly associated with various environmental changes and linked to abnormal gene expression within cells processing nociceptive signaling. Epigenetic regulation governs gene expression in response to environmental cues. Recent animal model and clinical studies indicate that epigenetic regulation plays an important role in the development/maintenance of persistent pain and, possibly the transition of acute pain to chronic pain, thus shedding light in a direction for development of new therapeutics for persistent pain. PMID:24948399

  16. Term Structure Persistence

    OpenAIRE

    Abbritti, M. (Mirko); Gil-Alana, L.A. (Luis A.); Lovcha, Y. (Yuliya); Moreno, A. (Antonio)

    2012-01-01

    Stationary I(0) models employed in yield curve analysis typically imply an unrealistically low degree of volatility in long-run short-rate expectations due to fast mean reversion. In this paper we propose a novel multivariate affine term structure model with a two-fold source of persistence in the yield curve: Long-memory and short-memory. Our model, based on an I(d) specification, nests the I(0) and I(1) models as special cases and the I(0) model is decisively rejected by the data. Our model...

  17. Export Mechanisms of Persistent Toxic Substances (PTSs) in Urban Land Uses during Rainfall-Runoff Events: Experimental and Modeling Studies

    Science.gov (United States)

    Zheng, Y.; Luo, X.; Lin, Z.

    2016-12-01

    The urban environment has a variety of Persistent Toxic Substances (PTS), such as Polycyclic Aromatic Hydrocarbons (PAHs) and mercury. Soil in pervious lands and dust deposited on impervious surfaces are two major sinks of PTSs in urbanized areas, which could contribute significant nonpoint source loadings of PTSs to adjacent waterbodies during rainfall-runoff events and therefore jeopardize aquatic ecosystems. However, PTSs have been much less understood regarding their export mechanisms in urban land uses, and efforts to model nonpoint source pollution processes of PTSs have been rare. We designed and performed in-lab rainfall-runoff simulation experiments to investigate transport of PAHs and mercury by runoff from urban soils. Organic petrology analysis (OPA) techniques were introduced to analyze the soil and sediment compositions. Our study revealed the limitation of the classic enrichment theory which attributes enrichment of pollutants in eroded sediment solely to the sediment's particle size distribution and adopts simple relationships between enrichment ratio and sediment flux. We found that carbonaceous materials (CMs) in soil are the direct and major sorbents for PAHs and mercury, and highly different in content, mobility and adsorption capacity for the PTSs. Anthropogenic CMs like black carbon components largely control the transport of soil PAHs, while humic substances have a dominant influence on the transport of soil mercury. A model was further developed to estimate the enrichment ratio of PAHs, which innovatively applies the fugacity concept.We also conducted field studies on export of PAHs by runoff from urban roads. A variable time-step model was developed to simulate the continuous cycles of PAH buildup and washoff on urban roads. The dependence of the pollution level on antecedent weather conditions was investigated and embodied in the model. The applicability of this approach and its value to environmental management was demonstrated by a case

  18. Optimizing Persistent Random Searches

    Science.gov (United States)

    Tejedor, Vincent; Voituriez, Raphael; Bénichou, Olivier

    2012-02-01

    We consider a minimal model of persistent random searcher with a short range memory. We calculate exactly for such a searcher the mean first-passage time to a target in a bounded domain and find that it admits a nontrivial minimum as function of the persistence length. This reveals an optimal search strategy which differs markedly from the simple ballistic motion obtained in the case of Poisson distributed targets. Our results show that the distribution of targets plays a crucial role in the random search problem. In particular, in the biologically relevant cases of either a single target or regular patterns of targets, we find that, in strong contrast to repeated statements in the literature, persistent random walks with exponential distribution of excursion lengths can minimize the search time, and in that sense perform better than any Levy walk.

  19. Evaluation of an integrated housing and recovery model for people with severe and persistent mental illnesses: the Doorway program.

    Science.gov (United States)

    Dunt, David R; Benoy, Andrew W; Phillipou, Andrea; Collister, Laura L; Crowther, Elizabeth M; Freidin, Julian; Castle, David J

    2017-10-01

    $1149 to A$19837 depending on the housing type comparator. Conclusion The Doorway program secured housing for this vulnerable group with additional benefits in client outcomes, including reduced use and cost of health services. These findings, if confirmed in larger studies, should have widespread applicability internationally. What is known about the topic? Beneficial effects of housing and recovery programs (Housing First) on people with severe and persistent mental illness and who are 'at risk', or actually homeless, are being demonstrated in Northern America. These effects include housing security, well being, health service utilisation and cost effects on government. However, these beneficial effects can only be regarded as settled for housing security. The highly innovative Doorway care model in which participants source and choose properties through the open rental market, with appropriate rental subsidy and brokerage support, has not been investigated previously. What does this paper add? This paper adds new data on the Doorway care models, it's effects and costs, particularly with regard to participant behavioural distress and social functioning. What are the implications for practitioners? The beneficial effects of this innovative model, if confirmed in larger studies, should have widespread applicability internationally.

  20. Processing plant persistent strains of Listeria monocytogenes appear to have a lower virulence potential than clinical strains in selected virulence models

    DEFF Research Database (Denmark)

    Jensen, Anne; Thomsen, L.E.; Jørgensen, R.L.

    2008-01-01

    cell line, Caco-2; time to death in a nematode model, Caenorhabditis elegans and in a fruit fly model, Drosophila melanogaster and fecal shedding in a guinea pig model. All strains adhered to and grew in Caco-2 cells in similar levels. When exposed to 10(6) CFU/ml, two strains representing......Listeria monocytogenes is an important foodborne bacterial pathogen that can colonize food processing equipment. One group of genetically similar L. monocytogenes strains (RAPID type 9) was recently shown to reside in several independent fish processing plants. Persistent strains are likely...... the persistent RAPD type 9 invaded Caco-2 cells in lower numbers (10(2)-10(3) CFU/ml) as compared to the four other strains (10(4)-10(6) CFU/ml), including food and human clinical strains. In the D. melanogaster model, the two RAPD type 9 strains were among the slowest to kill. Similarly, the time to reach 50...

  1. Modelling impact of climate change on atmospheric transport and fate of persistent organic pollutants in the Arctic

    Science.gov (United States)

    Hansen, K. M.; Christensen, J. H.; Geels, C.; Silver, J. D.; Brandt, J.

    2015-03-01

    The Danish Eulerian Hemispheric Model (DEHM) was applied to investigate how projected climate changes will affect the atmospheric transport of 13 persistent organic pollutants (POPs) to the Artic and their environmental fate within the Arctic. Two sets of simulations were performed, one with initial environmental concentrations from a 20 year spin-up simulation and one with initial environmental concentrations set to zero. Each set of simulations consisted of two ten-year time slices representing the present (1990-2000) and future (2090-2100) climate conditions. The same POP emissions were applied in all simulations to ensure that the difference in predicted concentrations for each set of simulations only arises from the difference in climate input. DEHM was driven using meteorological input from the global circulation model, ECHAM/MPI-OM, simulating the SRES A1B climate scenario. Under the applied climate and emission scenarios, the total mass of all compounds was predicted to be up to 20% higher across the Northern Hemisphere. The mass of HCHs within the Arctic was predicted to be up to 39% higher, whereas the change in mass of the PCBs was predicted to range from 14% lower to 17% higher depending on the congener and the applied initial environmental concentrations. The results of this study also indicate that contaminants with no or a short emission history will be more rapidly transported to and build up in the arctic environment in a future warmer climate. The process that dominates the environmental behaviour of POPs in the Arctic under a future warmer climate scenario is the shift in mass of POPs from the surface media to the atmosphere induced by the higher mean temperature. This is to some degree counteracted by higher degradation rates also following the higher mean temperature. The more dominant of these two processes depend on the physical-chemical properties of the compounds. Previous model studies have predicted that the effect of a changed climate on

  2. Modelling the impact of climate change on the atmospheric transport and the fate of persistent organic pollutants in the Arctic

    Science.gov (United States)

    Hansen, K. M.; Christensen, J. H.; Geels, C.; Silver, J. D.; Brandt, J.

    2015-06-01

    The Danish Eulerian Hemispheric Model (DEHM) was applied to investigate how projected climate changes will affect the atmospheric transport of 13 persistent organic pollutants (POPs) to the Arctic and their environmental fate within the Arctic. Three sets of simulations were performed, one with present day emissions and initial environmental concentrations from a 20-year spin-up simulation, one with present day emissions and with initial environmental concentrations set to zero and one without emissions but with initial environmental concentrations from the 20-year spin-up simulation. Each set of simulations consisted of two 10-year time slices representing the present (1990-2000) and future (2090-2100) climate conditions. DEHM was driven using meteorological input from the global circulation model, ECHAM/MPI-OM, simulating the SRES (Special Report on Emissions Scenarios) A1B climate scenario. Under the applied climate and emission scenarios, the total mass of all compounds was predicted to be up to 55 % lower across the Northern Hemisphere at the end of the 2090s than in the 1990s. The mass of HCHs within the Arctic was predicted to be up to 38 % higher, whereas the change in mass of the PCBs was predicted to range from 38 % lower to 17 % higher depending on the congener and the applied initial environmental concentrations. The results of this study also indicate that contaminants with no or a short emission history will be more rapidly transported to and build up in the arctic environment in a future warmer climate. The process that dominates the environmental behaviour of POPs in the Arctic under a future warmer climate scenario is the shift in mass of POPs from the surface media to the atmosphere induced by the higher mean temperature. This is to some degree counteracted by higher degradation rates also following the higher mean temperature. The more dominant of these two processes depends on the physical-chemical properties of the compounds. Previous model

  3. Modeling latently infected cell activation: viral and latent reservoir persistence, and viral blips in HIV-infected patients on potent therapy.

    Directory of Open Access Journals (Sweden)

    Libin Rong

    2009-10-01

    Full Text Available Although potent combination therapy is usually able to suppress plasma viral loads in HIV-1 patients to below the detection limit of conventional clinical assays, a low level of viremia frequently can be detected in plasma by more sensitive assays. Additionally, many patients experience transient episodes of viremia above the detection limit, termed viral blips, even after being on highly suppressive therapy for many years. An obstacle to viral eradication is the persistence of a latent reservoir for HIV-1 in resting memory CD4(+ T cells. The mechanisms underlying low viral load persistence, slow decay of the latent reservoir, and intermittent viral blips are not fully characterized. The quantitative contributions of residual viral replication to viral and the latent reservoir persistence remain unclear. In this paper, we probe these issues by developing a mathematical model that considers latently infected cell activation in response to stochastic antigenic stimulation. We demonstrate that programmed expansion and contraction of latently infected cells upon immune activation can generate both low-level persistent viremia and intermittent viral blips. Also, a small fraction of activated T cells revert to latency, providing a potential to replenish the latent reservoir. By this means, occasional activation of latently infected cells can explain the variable decay characteristics of the latent reservoir observed in different clinical studies. Finally, we propose a phenomenological model that includes a logistic term representing homeostatic proliferation of latently infected cells. The model is simple but can robustly generate the multiphasic viral decline seen after initiation of therapy, as well as low-level persistent viremia and intermittent HIV-1 blips. Using these models, we provide a quantitative and integrated prospective into the long-term dynamics of HIV-1 and the latent reservoir in the setting of potent antiretroviral therapy.

  4. Host resistance, population structure and the long-term persistence of bubonic plague: contributions of a modelling approach in the Malagasy focus.

    Directory of Open Access Journals (Sweden)

    Fanny Gascuel

    Full Text Available Although bubonic plague is an endemic zoonosis in many countries around the world, the factors responsible for the persistence of this highly virulent disease remain poorly known. Classically, the endemic persistence of plague is suspected to be due to the coexistence of plague resistant and plague susceptible rodents in natural foci, and/or to a metapopulation structure of reservoirs. Here, we test separately the effect of each of these factors on the long-term persistence of plague. We analyse the dynamics and equilibria of a model of plague propagation, consistent with plague ecology in Madagascar, a major focus where this disease is endemic since the 1920s in central highlands. By combining deterministic and stochastic analyses of this model, and including sensitivity analyses, we show that (i endemicity is favoured by intermediate host population sizes, (ii in large host populations, the presence of resistant rats is sufficient to explain long-term persistence of plague, and (iii the metapopulation structure of susceptible host populations alone can also account for plague endemicity, thanks to both subdivision and the subsequent reduction in the size of subpopulations, and extinction-recolonization dynamics of the disease. In the light of these results, we suggest scenarios to explain the localized presence of plague in Madagascar.

  5. Modeling the Impacts of National and Institutional Financial Aid Opportunities on Persistence at an Elite Chilean University

    Science.gov (United States)

    Horn, Catherine; Santelices, María Verónica; Avendaño, Ximena Catalán

    2014-01-01

    Much of the recent Chilean educational debate and reform has centered around issues of higher education cost, debt burden, and availability of grants versus loans. This quantitative case study of Pontificia Universidad Católica de Chile sought to understand the longitudinal contributions of combinations of types of financial aid to persistence of…

  6. Comparative evaluation of culture and PCR for the detection and determination of persistence of bacterial strains and DNAs in the Chinchilla laniger model of otitis media.

    Science.gov (United States)

    Aul, J J; Anderson, K W; Wadowsky, R M; Doyle, W J; Kingsley, L A; Post, J C; Ehrlich, G D

    1998-06-01

    This study was designed to determine the persistence of culturable bacteria versus DNA in the presence of a middle ear effusion in a chinchilla model of otitis media. Cohorts of animals were either infected with an ampicillin-resistant Haemophilus influenzae strain or injected with a tripartite inoculum consisting of freeze-thawed Streptococcus pneumoniae; pasteurized Moraxella catarrhalis; and DNA from H influenzae. The H influenzae-infected animals displayed culture positivity and polymerase chain reaction positivity through day 35. In the chinchillas infected with the low-copy number inocula of S pneumoniae, DNA was not detectable after day 1 from the co-inoculated pasteurized M catarrhalis bacteria or the purified H influenzae DNA; however, amplifiable DNA from the live low-copy number bacteria persisted through day 21 even though they were not culture-positive past day 3. These results demonstrate that DNA, and DNA from intact but nonviable bacteria, does not persist in an amplifiable form for more than a day in the presence of an effusion; however, live bacteria, while not culturable, persist in a viable state for weeks.

  7. Traumatic osteoarthritis-induced persistent mechanical hyperalgesia in a rat model of anterior cruciate ligament transection plus a medial meniscectomy

    Directory of Open Access Journals (Sweden)

    Tsai HC

    2017-12-01

    Full Text Available Hsiao-Chien Tsai,1–3 Ta-Liang Chen,2–4 Yu-Pin Chen,5 Ruei-Ming Chen1,3,6 1Graduate Institute of Medical Sciences, College of Medicine, Taipei Medical University, Taipei, Taiwan; 2Department of Anesthesiology, Taipei Medical University Hospital, Taipei Medical University, Taipei, Taiwan; 3Department of Anesthesiology, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan; 4Anesthesiology and Health Policy Research Center, Taipei Medical University Hospital, Taipei Medical University, Taipei, Taiwan; 5Department of Orthopedic Surgery, Wan Fang Hospital, Taipei Medical University, Taipei, Taiwan; 6Comprehensive Cancer Center, Taipei Medical University, Taipei, Taiwan Background: Osteoarthritis (OA is a degenerative joint disease characterized by progressive cartilage degeneration, subchondral bone changes, osteophyte formation, and synovitis. A major symptom is pain that is triggered by peripheral and central changes within the pain pathways. Some surgery-induced joint instability rat models of OA were described to mimic traumatic OA. Several behavioral tests were developed to access OA-induced pain. However, follow-up in most studies usually only occurred for about 4 weeks. Since traumatic OA is a chronic disease which gradually develops after trauma, the pattern of pain might differ between early and late stages after the trauma. Purpose: To observe the time-dependent development of hypersensitivity after traumatic OA and to determine the best timing and methods to investigate traumatic OA-induced pain.Methods: Anterior cruciate ligament transection plus medial meniscectomy was used to induce traumatic OA in Sprague-Dawley rats. Traumatic OA-induced pain was evaluated using four different behavioral tests for 15 weeks.Results: A significant difference in mechanical hypersensitivity developed throughout the observational period. It was worst in the first 3 weeks after the operation, then became less significant

  8. A probabilistic model in cross-sectional studies for identifying interactions between two persistent vector-borne pathogens in reservoir populations.

    Science.gov (United States)

    Vaumourin, Elise; Gasqui, Patrick; Buffet, Jean-Philippe; Chapuis, Jean-Louis; Pisanu, Benoît; Ferquel, Elisabeth; Vayssier-Taussat, Muriel; Vourc'h, Gwenaël

    2013-01-01

    In natural populations, individuals are infected more often by several pathogens than by just one. In such a context, pathogens can interact. This interaction could modify the probability of infection by subsequent pathogens. Identifying when pathogen associations correspond to biological interactions is a challenge in cross-sectional studies where the sequence of infection cannot be demonstrated. Here we modelled the probability of an individual being infected by one and then another pathogen, using a probabilistic model and maximum likelihood statistics. Our model was developed to apply to cross-sectional data, vector-borne and persistent pathogens, and to take into account confounding factors. Our modelling approach was more powerful than the commonly used Chi-square test of independence. Our model was applied to detect potential interaction between Borrelia afzelii and Bartonella spp. that infected a bank vole population at 11% and 57% respectively. No interaction was identified. The modelling approach we proposed is powerful and can identify the direction of potential interaction. Such an approach can be adapted to other types of pathogens, such as non-persistents. The model can be used to identify when co-occurrence patterns correspond to pathogen interactions, which will contribute to understanding how organism communities are assembled and structured. In the long term, the model's capacity to better identify pathogen interactions will improve understanding of infectious risk.

  9. A conceptual model for the blooming behavior and persistence of the benthic mat-forming diatom Didymosphenia geminata in oligotrophic streams

    Science.gov (United States)

    Cullis, James D. S.; Gillis, Carole-Anne; Bothwell, Max L.; Kilroy, Cathy; Packman, Aaron; Hassan, Marwan

    2012-06-01

    The benthic, mat-forming diatomDidymosphenia geminata has the unique ability to produce large amounts of algal biomass under oligotrophic conditions in cold, fast flowing streams and rivers. This presents an ecological paradox that challenges our current understanding of stream ecosystem dynamics. Our understanding of the drivers of D. geminata ecology is still limited. Here we present a conceptual model for the blooming behavior and persistence of this species to advance scientific understanding of strategies for life in fast flowing oligotrophic waters and support the design of future research and mitigation measures for nuisance algal blooms. The conceptual model is based on a synthesis of data and ideas from a range of disciplines including hydrology, geomorphology, biogeochemistry, and ecology. The conceptual model highlights the role of water chemistry, river morphology, and flow thresholds in defining the habitat window for D. geminata. We propose that bed disturbance is a primary control on accumulation and persistence of D. geminataand that the removal threshold can be determined by synthesizing site-specific information on hydrology and geomorphology. Further, we propose that a key to understanding the didymo paradox is the separation of cellular reproduction and mat morphology with specific controls acting in respect of the different processes.

  10. Object-oriented Persistent Homology.

    Science.gov (United States)

    Wang, Bao; Wei, Guo-Wei

    2016-01-15

    Persistent homology provides a new approach for the topological simplification of big data via measuring the life time of intrinsic topological features in a filtration process and has found its success in scientific and engineering applications. However, such a success is essentially limited to qualitative data classification and analysis. Indeed, persistent homology has rarely been employed for quantitative modeling and prediction. Additionally, the present persistent homology is a passive tool, rather than a proactive technique, for classification and analysis. In this work, we outline a general protocol to construct object-oriented persistent homology methods. By means of differential geometry theory of surfaces, we construct an objective functional, namely, a surface free energy defined on the data of interest. The minimization of the objective functional leads to a Laplace-Beltrami operator which generates a multiscale representation of the initial data and offers an objective oriented filtration process. The resulting differential geometry based object-oriented persistent homology is able to preserve desirable geometric features in the evolutionary filtration and enhances the corresponding topological persistence. The cubical complex based homology algorithm is employed in the present work to be compatible with the Cartesian representation of the Laplace-Beltrami flow. The proposed Laplace-Beltrami flow based persistent homology method is extensively validated. The consistence between Laplace-Beltrami flow based filtration and Euclidean distance based filtration is confirmed on the Vietoris-Rips complex for a large amount of numerical tests. The convergence and reliability of the present Laplace-Beltrami flow based cubical complex filtration approach are analyzed over various spatial and temporal mesh sizes. The Laplace-Beltrami flow based persistent homology approach is utilized to study the intrinsic topology of proteins and fullerene molecules. Based on a

  11. Using a Bayesian approach to estimate and compare new Keynesian DSGE models for the Brazilian economy: the role for endogenous persistence

    Directory of Open Access Journals (Sweden)

    Marcos Antonio C. da Silveira

    2008-09-01

    Full Text Available New Keynesian dynamic stochastic general equilibrium (DSGE models have been developed for monetary policy analysis in open economies. For this purpose, the basic model must be enriched with the sources of nominal and real rigidities which are capable of explaining the observed output and inflation persistence. Under this perspective, we use the Bayesian approach to estimate and compare alternative model specifications for the Brazilian economy with respect to two endogenous persistence mechanisms widely supported by the international empirical literature: habit formation and price indexation. Using data for the inflation target period, we conclude for the relevance of both mechanisms, although the evidence is unexpectly less robust for price indexation. Furthermore, impulse-response functions are built to describe the dynamic effects of domestic and foreign real and monetary shocks.Modelos de equilíbrio geral dinâmicos e estocásticos têm sido desenvolvidos para a análise de política monetária em economias abertas. Com este propósito, o modelo básico precisa ser enriquecido com as fontes de rigidez nominal e real que são capazes de explicar a persistência observada no produto e na inflação. Com esta perspectiva, a metodologia bayesiana é usada para estimar e comparar alternativas especificações de modelos para a economia brasileira no tocante a dois mecanismos endógenos de persistência amplamente postulados pela literatura empírica internacional: formação de hábito e indexação de preços. Usando dados do período de metas de inflação, nossa conclusão é pela relevância de ambos os mecanismos, embora a evidência seja inesperadamente menos robusta para indexação de preços. Além disso, funções impulsoresposta são construídas para descrever os efeitos dinâmicos de choques estruturais domésticos e externos, reais e monetários.

  12. Academic locus of control and motivational persistence: structural equation modeling [Akademik kontrol odağı ve motivasyonel kararlılık: yapısal eşitlik modellemesi

    Directory of Open Access Journals (Sweden)

    Hakan SARIÇAM

    2015-04-01

    Full Text Available The aim of this study is the examination of the relationship between academic locus of control and motivational persistence. For the first time to my knowledge, the relations between academic locus of control and motivational persistence were investigated. The participants of the study consisted of adolescents who have attended from different public high schools. Overall, 413 students contributed to this study. Academic Locus of Control Scale and The Motivational Persistence Scale were used for data collection. In the research, whether there is a casual relationship between academic locus of control and motivational persistence in adolescents was tested through path analysis in the context of structural equation model. According to the results, there is a causative relationship between academic locus of control and motivational persistence in adolescents. The findings were discussed in relation to previous research.

  13. Coupled atmosphere-soil-vegetation modelling for the assessment of the impact of atmospheric releases of heavy metals and of persistent organic pollutants at the European scale

    International Nuclear Information System (INIS)

    Queguiner, Solen

    2008-01-01

    The objective of this research thesis is to couple a model of atmospheric dispersion with a multi-environment model in order to perform impact studies related to atmospheric pollution by heavy metals and POPs (persistent organic pollutants). The author first presents the studied pollutants, their physical and chemical properties, and their effects on health. Then, he addresses the atmospheric modelling with a presentation of the used atmospheric dispersion model (POLAIR3D), and an application to heavy metals. Simulations are performed on a 4-year period in order to try to represent the inter-annual variability of atmospheric lead and cadmium concentrations. The next part reports the modelling of POPs which required the introduction of a soil model to address re-emissions. Results are compared with provided measurements. The fourth part reports the modelling of agricultural environments in the impact model, and more particularly physical processes and parameters proper to heavy metals and POPs. The author finally reports two case studies, one related to heavy metals, and the other to POPs [fr

  14. Response surface modeling for optimization heterocatalytic Fenton oxidation of persistence organic pollution in high total dissolved solid containing wastewater.

    Science.gov (United States)

    Sekaran, G; Karthikeyan, S; Boopathy, R; Maharaja, P; Gupta, V K; Anandan, C

    2014-01-01

    The rice-husk-based mesoporous activated carbon (MAC) used in this study was precarbonized and activated using phosphoric acid. N2 adsorption/desorption isotherm, X-ray powder diffraction, electron spin resonance, X-ray photoelectron spectroscopy and scanning electron microscopy, transmission electron microscopy, (29)Si-NMR spectroscopy, and diffuse reflectance spectroscopy were used to characterize the MAC. The tannery wastewater carrying high total dissolved solids (TDS) discharged from leather industry lacks biodegradability despite the presence of dissolved protein. This paper demonstrates the application of free electron-rich MAC as heterogeneous catalyst along with Fenton reagent for the oxidation of persistence organic compounds in high TDS wastewater. The heterogeneous Fenton oxidation of the pretreated wastewater at optimum pH (3.5), H2O2 (4 mmol/L), FeSO4[Symbol: see text]7H2O (0.2 mmol/L), and time (4 h) removed chemical oxygen demand, biochemical oxygen demand, total organic carbon and dissolved protein by 86, 91, 83, and 90%, respectively.

  15. Increasing the persistence of a heterogeneous behavior chain: Studies of extinction in a rat model of search behavior of working dogs.

    Science.gov (United States)

    Thrailkill, Eric A; Kacelnik, Alex; Porritt, Fay; Bouton, Mark E

    2016-08-01

    Dogs trained to search for contraband perform a chain of behavior in which they first search for a target and then make a separate response that indicates to the trainer that they have found one. The dogs often conduct multiple searches without encountering a target and receiving the reinforcer (i.e., no contraband is present). Understanding extinction (i.e., the decline in work rate when reinforcers are no longer encountered) may assist in training dogs to work in conditions where targets are rare. We therefore trained rats on a search-target behavior chain modeled on the search behavior of working dogs. A discriminative stimulus signaled that a search response (e.g., chain pull) led to a second stimulus that set the occasion for a target response (e.g., lever press) that was reinforced by a food pellet. In Experiment 1 training with longer search durations and intermittent (partial) reinforcement of searching (i.e. some trials had no target present) both led to more persistent search responding in extinction. The loss of search behavior in extinction was primarily dependent on the number of non-reinforced searches rather than time searching without reinforcement. In Experiments 2 and 3, delivery of non-contingent reinforcers during extinction increased search persistence provided they had also been presented during training. Thus, results with rats suggest that the persistence of working dog performance (or chained behavior generally) may be improved by training with partial reinforcement of searching and non-contingent reinforcement during both training and work (extinction). Copyright © 2016 Elsevier B.V. All rights reserved.

  16. In Vivo Safety and Persistence of Endoribonuclease Gene-Transduced CD4+ T Cells in Cynomolgus Macaques for HIV-1 Gene Therapy Model

    Science.gov (United States)

    Chono, Hideto; Saito, Naoki; Tsuda, Hiroshi; Shibata, Hiroaki; Ageyama, Naohide; Terao, Keiji; Yasutomi, Yasuhiro; Mineno, Junichi; Kato, Ikunoshin

    2011-01-01

    Background MazF is an endoribonuclease encoded by Escherichia coli that specifically cleaves the ACA sequence of mRNA. In our previous report, conditional expression of MazF in the HIV-1 LTR rendered CD4+ T lymphocytes resistant to HIV-1 replication. In this study, we examined the in vivo safety and persistence of MazF-transduced cynomolgus macaque CD4+ T cells infused into autologous monkeys. Methodology/Principal Findings The in vivo persistence of the gene-modified CD4+ T cells in the peripheral blood was monitored for more than half a year using quantitative real-time PCR and flow cytometry, followed by experimental autopsy in order to examine the safety and distribution pattern of the infused cells in several organs. Although the levels of the MazF-transduced CD4+ T cells gradually decreased in the peripheral blood, they were clearly detected throughout the experimental period. Moreover, the infused cells were detected in the distal lymphoid tissues, such as several lymph nodes and the spleen. Histopathological analyses of tissues revealed that there were no lesions related to the infused gene modified cells. Antibodies against MazF were not detected. These data suggest the safety and the low immunogenicity of MazF-transduced CD4+ T cells. Finally, gene modified cells harvested from the monkey more than half a year post-infusion suppressed the replication of SHIV 89.6P. Conclusions/Significance The long-term persistence, safety and continuous HIV replication resistance of the mazF gene-modified CD4+ T cells in the non-human primate model suggests that autologous transplantation of mazF gene-modified cells is an attractive strategy for HIV gene therapy. PMID:21858176

  17. New-found fundamentals of bacterial persistence.

    Science.gov (United States)

    Kint, Cyrielle I; Verstraeten, Natalie; Fauvart, Maarten; Michiels, Jan

    2012-12-01

    Persister cells display tolerance to high doses of bactericidal antibiotics and typically comprise a small fraction of a bacterial population. Recently, evidence was provided for a causal link between therapy failure and the presence of persister cells in chronic infections, underscoring the need for research on bacterial persistence. A series of recent breakthroughs have shed light on the multiplicity of persister genes, the contribution of gene expression noise to persister formation, the importance of active responses to antibiotic tolerance and heterogeneity among persister cells. Moreover, the development of in vivo model systems has highlighted the clinical relevance of persistence. This review discusses these recent advances and how this knowledge fundamentally changes the way in which we will perceive the problem of antibiotic tolerance in years to come. Copyright © 2012 Elsevier Ltd. All rights reserved.

  18. Six persistent research misconceptions.

    Science.gov (United States)

    Rothman, Kenneth J

    2014-07-01

    Scientific knowledge changes rapidly, but the concepts and methods of the conduct of research change more slowly. To stimulate discussion of outmoded thinking regarding the conduct of research, I list six misconceptions about research that persist long after their flaws have become apparent. The misconceptions are: 1) There is a hierarchy of study designs; randomized trials provide the greatest validity, followed by cohort studies, with case-control studies being least reliable. 2) An essential element for valid generalization is that the study subjects constitute a representative sample of a target population. 3) If a term that denotes the product of two factors in a regression model is not statistically significant, then there is no biologic interaction between those factors. 4) When categorizing a continuous variable, a reasonable scheme for choosing category cut-points is to use percentile-defined boundaries, such as quartiles or quintiles of the distribution. 5) One should always report P values or confidence intervals that have been adjusted for multiple comparisons. 6) Significance testing is useful and important for the interpretation of data. These misconceptions have been perpetuated in journals, classrooms and textbooks. They persist because they represent intellectual shortcuts that avoid more thoughtful approaches to research problems. I hope that calling attention to these misconceptions will spark the debates needed to shelve these outmoded ideas for good.

  19. Persistence of airline accidents.

    Science.gov (United States)

    Barros, Carlos Pestana; Faria, Joao Ricardo; Gil-Alana, Luis Alberiko

    2010-10-01

    This paper expands on air travel accident research by examining the relationship between air travel accidents and airline traffic or volume in the period from 1927-2006. The theoretical model is based on a representative airline company that aims to maximise its profits, and it utilises a fractional integration approach in order to determine whether there is a persistent pattern over time with respect to air accidents and air traffic. Furthermore, the paper analyses how airline accidents are related to traffic using a fractional cointegration approach. It finds that airline accidents are persistent and that a (non-stationary) fractional cointegration relationship exists between total airline accidents and airline passengers, airline miles and airline revenues, with shocks that affect the long-run equilibrium disappearing in the very long term. Moreover, this relation is negative, which might be due to the fact that air travel is becoming safer and there is greater competition in the airline industry. Policy implications are derived for countering accident events, based on competition and regulation. © 2010 The Author(s). Journal compilation © Overseas Development Institute, 2010.

  20. Proposal of a socio-cognitive-behavioral structural equation model of internalized stigma in people with severe and persistent mental illness.

    Science.gov (United States)

    Muñoz, Manuel; Sanz, María; Pérez-Santos, Eloísa; Quiroga, María de Los Ángeles

    2011-04-30

    The social stigma of mental illness has received much attention in recent years and its effects on diverse variables such as psychiatric symptoms, social functioning, self-esteem, self-efficacy, quality of life, and social integration are well established. However, internalized stigma in people with severe and persistent mental illness has not received the same attention. The aim of the present work was to study the relationships between the principal variables involved in the functioning of internalized stigma (sociodemographic and clinical variables, social stigma, psychosocial functioning, recovery expectations, empowerment, and discrimination experiences) in a sample of people with severe and persistent mental illness (N=108). The main characteristics of the sample and the differences between groups with high and low internalized stigma were analyzed, a correlation analysis of the variables was performed, and a structural equation model, integrating variables of social, cognitive, and behavioral content, was proposed and tested. The results indicate the relationships among social stigma, discrimination experiences, recovery expectation, and internalized stigma and their role in the psychosocial and behavioral outcomes in schizophrenia spectrum disorders. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

  1. Long-term persistence and function of hematopoietic stem cell-derived chimeric antigen receptor T cells in a nonhuman primate model of HIV/AIDS.

    Directory of Open Access Journals (Sweden)

    Anjie Zhen

    2017-12-01

    Full Text Available Chimeric Antigen Receptor (CAR T-cells have emerged as a powerful immunotherapy for various forms of cancer and show promise in treating HIV-1 infection. However, significant limitations are persistence and whether peripheral T cell-based products can respond to malignant or infected cells that may reappear months or years after treatment remains unclear. Hematopoietic Stem/Progenitor Cells (HSPCs are capable of long-term engraftment and have the potential to overcome these limitations. Here, we report the use of a protective CD4 chimeric antigen receptor (C46CD4CAR to redirect HSPC-derived T-cells against simian/human immunodeficiency virus (SHIV infection in pigtail macaques. CAR-containing cells persisted for more than 2 years without any measurable toxicity and were capable of multilineage engraftment. Combination antiretroviral therapy (cART treatment followed by cART withdrawal resulted in lower viral rebound in CAR animals relative to controls, and demonstrated an immune memory-like response. We found CAR-expressing cells in multiple lymphoid tissues, decreased tissue-associated SHIV RNA levels, and substantially higher CD4/CD8 ratios in the gut as compared to controls. These results show that HSPC-derived CAR T-cells are capable of long-term engraftment and immune surveillance. This study demonstrates for the first time the safety and feasibility of HSPC-based CAR therapy in a large animal preclinical model.

  2. Sensitivity of reentrant driver localization to electrophysiological parameter variability in image-based computational models of persistent atrial fibrillation sustained by a fibrotic substrate

    Science.gov (United States)

    Deng, Dongdong; Murphy, Michael J.; Hakim, Joe B.; Franceschi, William H.; Zahid, Sohail; Pashakhanloo, Farhad; Trayanova, Natalia A.; Boyle, Patrick M.

    2017-09-01

    Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia, causing morbidity and mortality in millions worldwide. The atria of patients with persistent AF (PsAF) are characterized by the presence of extensive and distributed atrial fibrosis, which facilitates the formation of persistent reentrant drivers (RDs, i.e., spiral waves), which promote fibrillatory activity. Targeted catheter ablation of RD-harboring tissues has shown promise as a clinical treatment for PsAF, but the outcomes remain sub-par. Personalized computational modeling has been proposed as a means of non-invasively predicting optimal ablation targets in individual PsAF patients, but it remains unclear how RD localization dynamics are influenced by inter-patient variability in the spatial distribution of atrial fibrosis, action potential duration (APD), and conduction velocity (CV). Here, we conduct simulations in computational models of fibrotic atria derived from the clinical imaging of PsAF patients to characterize the sensitivity of RD locations to these three factors. We show that RDs consistently anchor to boundaries between fibrotic and non-fibrotic tissues, as delineated by late gadolinium-enhanced magnetic resonance imaging, but those changes in APD/CV can enhance or attenuate the likelihood that an RD will anchor to a specific site. These findings show that the level of uncertainty present in patient-specific atrial models reconstructed without any invasive measurements (i.e., incorporating each individual's unique distribution of fibrotic tissue from medical imaging alongside an average representation of AF-remodeled electrophysiology) is sufficiently high that a personalized ablation strategy based on targeting simulation-predicted RD trajectories alone may not produce the desired result.

  3. A joint model of persistent human papillomavirus infection and cervical cancer risk: Implications for cervical cancer screening.

    Science.gov (United States)

    Katki, Hormuzd A; Cheung, Li C; Fetterman, Barbara; Castle, Philip E; Sundaram, Rajeshwari

    2015-10-01

    New cervical cancer screening guidelines in the US and many European countries recommend that women get tested for human papillomavirus (HPV). To inform decisions about screening intervals, we calculate the increase in precancer/cancer risk per year of continued HPV infection. However, both time to onset of precancer/cancer and time to HPV clearance are interval-censored, and onset of precancer/cancer strongly informatively censors HPV clearance. We analyze this bivariate informatively interval-censored data by developing a novel joint model for time to clearance of HPV and time to precancer/cancer using shared random-effects, where the estimated mean duration of each woman's HPV infection is a covariate in the submodel for time to precancer/cancer. The model was fit to data on 9,553 HPV-positive/Pap-negative women undergoing cervical cancer screening at Kaiser Permanente Northern California, data that were pivotal to the development of US screening guidelines. We compare the implications for screening intervals of this joint model to those from population-average marginal models of precancer/cancer risk. In particular, after 2 years the marginal population-average precancer/cancer risk was 5%, suggesting a 2-year interval to control population-average risk at 5%. In contrast, the joint model reveals that almost all women exceeding 5% individual risk in 2 years also exceeded 5% in 1 year, suggesting that a 1-year interval is better to control individual risk at 5%. The example suggests that sophisticated risk models capable of predicting individual risk may have different implications than population-average risk models that are currently used for informing medical guideline development.

  4. Topical spinal administration of a nitric oxide synthase inhibitor prevents the hyper-reflexia associated with a rat model of persistent visceral pain.

    Science.gov (United States)

    Rice, A S

    1995-03-03

    The effects of a neuronal selective nitric oxide synthase (NOS) inhibitor, L-Ng-nitro arginine p-nitroanilide (L-Napna), upon the hyper-reflexia of a rat model of persistent visceral pain was investigated. A baseline cystometrogram (CMG) was performed by measuring intravesical pressure during vesical inflation. L-Napna (125-1000 micrograms) or vehicle (control) was then administered topically onto the exposed spinal cord, followed by another CMG. The bladder was then inflamed with turpentine and a final CMG performed. Neither L-Napna nor vehicle affected vesical reflexes in the absence of inflammation. However, following inflammation, a vesical hyper-reflexia was demonstrated in the control animals, which was prevented by L-Napna. Therefore, spinal NOS does not have a role in the generation of normal bladder reflexes, however it does modulate them during vesical inflammation.

  5. The influence of agroforestry and other land-use types on the persistence of a Sumatran tiger (Panthera tigris sumatrae) population: an individual-based model approach.

    Science.gov (United States)

    Imron, Muhammad Ali; Herzog, Sven; Berger, Uta

    2011-08-01

    The importance of preserving both protected areas and their surrounding landscapes as one of the major conservation strategies for tigers has received attention over recent decades. However, the mechanism of how land-use surrounding protected areas affects the dynamics of tiger populations is poorly understood. We developed Panthera Population Persistence (PPP)--an individual-based model--to investigate the potential mechanism of the Sumatran tiger population dynamics in a protected area and under different land-use scenarios surrounding the reserve. We tested three main landscape compositions (single, combined and real land-uses of Tesso-Nilo National Park and its surrounding area) on the probability of and time to extinction of the Sumatran tiger over 20 years in Central Sumatra. The model successfully explains the mechanisms behind the population response of tigers under different habitat landscape compositions. Feeding and mating behaviours of tigers are key factors, which determined population persistence in a heterogeneous landscape. All single land-use scenarios resulted in tiger extinction but had a different probability of extinction within 20 years. If tropical forest was combined with other land-use types, the probability of extinction was smaller. The presence of agroforesty and logging concessions adjacent to protected areas encouraged the survival of tiger populations. However, with the real land-use scenario of Tesso-Nilo National Park, tigers could not survive for more than 10 years. Promoting the practice of agroforestry systems surrounding the park is probably the most reasonable way to steer land-use surrounding the Tesso-Nilo National Park to support tiger conservation.

  6. Why did distinct types of dual-earner models in Czech, Slovak and East German societies develop and persist?

    Czech Academy of Sciences Publication Activity Database

    Hašková, Hana; Klenner, Ch.

    2010-01-01

    Roč. 22, č. 3 (2010), s. 266-288 ISSN 1437-2940 R&D Projects: GA AV ČR IAA700280901; GA ČR GAP404/10/0021 Institutional research plan: CEZ:AV0Z70280505 Keywords : dual earner model * Central and Eastern Europe Subject RIV: AO - Sociology , Demography Impact factor: 0.037, year: 2010

  7. A processing plant persistent strain of Listeria monocytogenes crosses the fetoplacental barrier in a pregnant guinea pig model

    DEFF Research Database (Denmark)

    Jensen, Anne; Williams, D.; Irving, E. A.

    2008-01-01

    independent fish processing plants. The purpose of the present study was to determine the virulence potential of one RAPD type 9 strain (La111), one human clinical strain (Scott A), and one monkey clinical strain (12443) in a pregnant guinea pig model. Animals were orally exposed to 10(8) CFU of L...

  8. A novel human breast milk-fed piglet model to examine persistent effects of neonatal diet on duodenal microbiota composition

    Science.gov (United States)

    Sow milk (SM) feeding has been studied in piglets as a model of human breast milk (HBM) feeding in infants; however, the composition of HBM differs from SM and may impart differing effects on colonization of the gut microbiota. The objective of this study was to determine if HBM feeding from birth t...

  9. Causes and Model Skill of the Persistent Intense Rainfall and Flooding in Paraguay during the Austral Summer 2015-2016

    Science.gov (United States)

    Doss-Gollin, J.; Munoz, A. G.; Pastén, M.

    2017-12-01

    During the austral summer 2015-16 severe flooding displaced over 150,000 people on the Paraguay River system in Paraguay, Argentina, and Southern Brazil. This flooding was out of phase with the typical seasonal cycle of the Paraguay River, and was driven by repeated intense rainfall events in the Lower Paraguay River basin. Using a weather typing approach within a diagnostic framework, we show that enhanced moisture inflow from the low-level jet and local convergence associated with baroclinic systems favored the development of mesoscale convective activity and enhanced precipitation. The observed circulation patterns were made more likely by the cross-timescale interactions of multiple climate mechanisms including the strong, mature El Niño event and an active Madden-Julien Oscillation in phases four and five. We also perform a comparison of the rainfall predictability using seasonal forecasts from the Latin American Observatory of Climate Events (OLE2) and sub-seasonal forecasts produced by the ECMWF. We find that the model output precipitation field exhibited limited skill at lead times beyond the synoptic timescale, but that a Model Output Statistics (MOS) approach, in which the leading principal components of the observed rainfall field are regressed on the leading principal components of model-simulated rainfall fields, substantially improves spatial representation of rainfall forecasts. Possible implications for flood preparedness are briefly discussed.

  10. Análises da persistência na lactação de vacas da raça Holandesa, usando produção no dia do controle e modelo de regressão aleatória Analysis of persistency in the lactation of Holstein cows using test-day yield and random regression model

    Directory of Open Access Journals (Sweden)

    Jaime Araujo Cobuci

    2004-06-01

    Full Text Available Foram utilizados 87.045 registros de produção de leite, na primeira lactação, de 11.023 vacas da raça Holandesa, obtidos nos anos de 1997 a 2001, em diferentes rebanhos distribuídos em dez núcleos do Estado de Minas Gerais. Foram avaliados seis tipos de mensuração da persistência na lactação utilizando-se os valores genéticos da produção de leite, obtidos por meio do modelo de regressão aleatória - MRA. Utilizou-se a função de Wilmink na descrição dos efeitos aleatórios e fixos, pelo MRA. As estimativas de herdabilidade e de correlação genética, para as várias mensurações da persistência na lactação, variaram em decorrência da definição da persistência. As estimativas de herdabilidade para persistência na lactação variaram de 0,11 a 0,27 e as estimativas de correlação genética entre as mensurações da persistência na lactação e produção de leite até 305 dias, de -0,31 a 0,55, indicando que a persistência na lactação é uma característica de moderada herdabilidade e pouco correlacionada com a produção de leite até 305 dias. A seleção de animais para persistência na lactação, com o objetivo de alterar a forma da curva de lactação, pode ser eficiente.A total of 87,045 milk yield records of 11,023 first-parity Holstein cows was utilized, obtained from 1997 to 2001 from different herds of 10 Minas Gerais locations. Six types of persistency measures in lactation were evaluated using milk yield breeding values, obtained by means of Random Regression Model - RRM. The Wilmink function was used to describe the random and fixed effects by RRM. Heritability estimates and genetic correlations for various persistency measures in lactation were dependent on the definition of persistency. The heritability estimates for persistency in lactation ranged from 0.11 to 0.27 and the genetic variations among persistency measures in lactation and milk yield up to d 305 ranged from -0.31 to 0.55, showing that

  11. Demographics of antibiotic persistence

    DEFF Research Database (Denmark)

    Kollerova, Silvia; Jouvet, Lionel; Steiner, Ulrich

    Persister cells, cells that can survive antibiotic exposure but lack heritable antibiotic resistance, are assumed to play a crucial role for the evolution of antibiotic resistance. Persistence is a stage associated with reduced metabolic activity. Most previous studies have been done on batch...... cultures, rather than the individual level. Here, we used individual level bacteria data to confirm previous studies in how fast cells switch into a persistence stage, but our results challenge the fundamental idea that persistence comes with major costs of reduced growth (cell elongation) and division due...... even play a more prominent role for the evolution of resistance and failures of medical treatment by antibiotics as currently assumed....

  12. Using Garch-in-Mean Model to Investigate Volatility and Persistence at Different Frequencies for Bucharest Stock Exchange during 1997-2012

    Directory of Open Access Journals (Sweden)

    Iulian PANAIT

    2012-05-01

    Full Text Available In our paper we use data mining to compare the volatility structure of high (daily and low (weekly, monthly frequencies for seven Romanian companies traded on Bucharest Stock Exchange and three market indices, during 1997-2012. For each of the 10 time series and three frequencies we fit a GARCH-in-mean model and we find that persistency is more present in the daily returns as compared with the weekly and monthly series. On the other hand, the GARCH-in-mean failed to confirm (on our data the theoretical hypothesis that an increase in volatility leads to a rise in future returns, mainly because the variance coefficient from the mean equation of the model was not statistically significant for most of the time series analyzed and on most of the frequencies. The diagnosis that we ran in order the verify the goodness of fit for the model showed that GARCH-in-mean was well fitted on the weekly and monthly time series but behaved less well on the daily time series.

  13. The Influence of Agroforestry and Other Land-Use Types on the Persistence of a Sumatran Tiger ( Panthera tigris sumatrae) Population: An Individual-Based Model Approach

    Science.gov (United States)

    Imron, Muhammad Ali; Herzog, Sven; Berger, Uta

    2011-08-01

    The importance of preserving both protected areas and their surrounding landscapes as one of the major conservation strategies for tigers has received attention over recent decades. However, the mechanism of how land-use surrounding protected areas affects the dynamics of tiger populations is poorly understood. We developed Panthera Population Persistence (PPP)—an individual-based model—to investigate the potential mechanism of the Sumatran tiger population dynamics in a protected area and under different land-use scenarios surrounding the reserve. We tested three main landscape compositions (single, combined and real land-uses of Tesso-Nilo National Park and its surrounding area) on the probability of and time to extinction of the Sumatran tiger over 20 years in Central Sumatra. The model successfully explains the mechanisms behind the population response of tigers under different habitat landscape compositions. Feeding and mating behaviours of tigers are key factors, which determined population persistence in a heterogeneous landscape. All single land-use scenarios resulted in tiger extinction but had a different probability of extinction within 20 years. If tropical forest was combined with other land-use types, the probability of extinction was smaller. The presence of agroforesty and logging concessions adjacent to protected areas encouraged the survival of tiger populations. However, with the real land-use scenario of Tesso-Nilo National Park, tigers could not survive for more than 10 years. Promoting the practice of agroforestry systems surrounding the park is probably the most reasonable way to steer land-use surrounding the Tesso-Nilo National Park to support tiger conservation.

  14. Persistence and proliferation of human mesenchymal stromal cells in the right ventricular myocardium after intracoronary injection in a large animal model of pulmonary hypertension.

    Science.gov (United States)

    Badr Eslam, Roza; Croce, Kevin; Mangione, Fernanda Marinho; Musmann, Robert; Leopold, Jane A; Mitchell, Richard N; Waxman, Aaron B

    2017-06-01

    In this study, we demonstrate long-term persistence of human mesenchymal stromal cells (hMSCs) after intracoronary injection in a large animal model of pulmonary hypertension (PH). Commercially available placenta-derived hMSCs were used. Experiments were conducted on 14 female Yorkshire swine. Four animals served as controls, and 10 underwent pulmonary vein (PV) banding. After 12 ± 2 weeks, PH and PV dysfunction were confirmed by right heart catheterization and cardiac magnetic resonance imaging. hMSCs were injected in the marginal branch of the right coronary artery. Tissues were harvested 6, 9 or 24 days after infusion. After 12 ± 2 weeks after PV banding, all subjects had increased mean pulmonary artery pressure (13.6 ± 3.6 versus 30.8 ± 4.5 mm Hg, P cells in the right ventricle (RV) that were Ki67 + . This was confirmed by fluorescence in situ hybridization. CD45 + porcine inflammatory cells were identified, commonly seen adjacent to areas of healing microscopic infarction that likely dated to the time of the original hMSC injection. Anti-CD31 staining produced strong signals in areas of injected hMSCs. Immunohistochemistry staining for vascular cell adhesion molecule-1 showed upregulation in the clusters, where mononuclear cells were located. hMSCs injected via intracoronary infusion survived up to 24 days and demonstrated proliferative capacity. hMSCs can persist long term in the RV and are potential cell source for tissue repair in RV dysfunction. Copyright © 2017 International Society for Cellular Therapy. Published by Elsevier Inc. All rights reserved.

  15. Contribution of amino acid catabolism to the tissue specific persistence of Campylobacter jejuni in a murine colonization model.

    Directory of Open Access Journals (Sweden)

    Dirk Hofreuter

    Full Text Available Campylobacter jejuni is a major cause of food-borne disease in industrialized countries. Carbohydrate utilization by C. jejuni is severely restricted, and knowledge about which substrates fuel C. jejuni infection and growth is limited. Some amino acids have been shown to serve as carbon sources both in vitro and in vivo. In the present study we investigated the contribution of serine and proline catabolism to the invitro and invivo growth of C. jejuni 81-176. We confirmed that the serine transporter SdaC and the serine ammonia-lyase SdaA are required for serine utilization, and demonstrated that a predicted proline permease PutP and a bifunctional proline/delta-1-pyrroline-5-carboxylate dehydrogenase PutA are required for proline utilization by C. jejuni 81-176. C. jejuni 81-176 mutants unable to utilize serine were shown to be severely defective for colonization of the intestine and systemic tissues in a mouse model of infection. In contrast, C. jejuni 81-176 mutants unable to utilize proline were only defective for intestinal colonization. These results further emphasize the importance of amino acid utilization in C. jejuni colonization of various tissues.

  16. Persistent pulmonary subsolid nodules: model-based iterative reconstruction for nodule classification and measurement variability on low-dose CT.

    Science.gov (United States)

    Kim, Hyungjin; Park, Chang Min; Kim, Seong Ho; Lee, Sang Min; Park, Sang Joon; Lee, Kyung Hee; Goo, Jin Mo

    2014-11-01

    To compare the pulmonary subsolid nodule (SSN) classification agreement and measurement variability between filtered back projection (FBP) and model-based iterative reconstruction (MBIR). Low-dose CTs were reconstructed using FBP and MBIR for 47 patients with 47 SSNs. Two readers independently classified SSNs into pure or part-solid ground-glass nodules, and measured the size of the whole nodule and solid portion twice on both reconstruction algorithms. Nodule classification agreement was analyzed using Cohen's kappa and compared between reconstruction algorithms using McNemar's test. Measurement variability was investigated using Bland-Altman analysis and compared with the paired t-test. Cohen's kappa for inter-reader SSN classification agreement was 0.541-0.662 on FBP and 0.778-0.866 on MBIR. Between the two readers, nodule classification was consistent in 79.8 % (75/94) with FBP and 91.5 % (86/94) with MBIR (p = 0.027). Inter-reader measurement variability range was -5.0-2.1 mm on FBP and -3.3-1.8 mm on MBIR for whole nodule size, and was -6.5-0.9 mm on FBP and -5.5-1.5 mm on MBIR for solid portion size. Inter-reader measurement differences were significantly smaller on MBIR (p = 0.027, whole nodule; p = 0.011, solid portion). MBIR significantly improved SSN classification agreement and reduced measurement variability of both whole nodules and solid portions between readers. • Low-dose CT using MBIR algorithm improves reproducibility in the classification of SSNs. • MBIR would enable more confident clinical planning according to the SSN type. • Reduced measurement variability on MBIR allows earlier detection of potentially malignant nodules.

  17. [The changing profile of caregivers of persons aged 65 years and over with disabilities within a persisting family care model].

    Science.gov (United States)

    Zueras, Pilar; Spijker, Jeroen; Blanes, Amand

    The increasing participation of women in the workforce may make it difficult to sustain the current model of elderly care. The aim of this article was to determine the changing sociodemographic profile of informal elderly caregivers with disabilities, the interaction between employment and care, and the view of the public on the responsibility of that care. Cross-sectional analysis of secondary data from four national surveys were used: the disability surveys held in 1999 (N=3,936) and 2008 (N=5,257), the 2011-12 National Health Survey (N=439), and the Family and Gender survey of 2012 (N=1,359). They were analysed using contingency tables based on gender and age. Half of the informal caregivers were women aged 45 to 64 years. Between 1999 and 2011-12 they became more concentrated in the 55-64 age-bracket, among whom participation in the workforce doubled from 20% to 40%. Increased care for men was associated with unemployment. Care work had a negative impact on working life, with greater impact among women and those who cared for elderly people with severe disabilities. Less likely to consider that elderly care provision should rest on family are 45-54 year-old economically active women (only 42%) or those who are more educated (40%), compared to 60% of economically inactive women and 55% of less educated women. Economically active and educated women are less inclined to family-based care, but assume it independently of their workforce participation, whereas males do so according to their availability. Copyright © 2017 SEGG. Publicado por Elsevier España, S.L.U. All rights reserved.

  18. Persistent pulmonary subsolid nodules: model-based iterative reconstruction for nodule classification and measurement variability on low-dose CT

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyungjin; Kim, Seong Ho; Lee, Sang Min; Lee, Kyung Hee [Seoul National University College of Medicine, Department of Radiology, Seoul (Korea, Republic of); Seoul National University Medical Research Center, Institute of Radiation Medicine, Seoul (Korea, Republic of); Park, Chang Min; Park, Sang Joon; Goo, Jin Mo [Seoul National University College of Medicine, Department of Radiology, Seoul (Korea, Republic of); Seoul National University Medical Research Center, Institute of Radiation Medicine, Seoul (Korea, Republic of); Seoul National University, Cancer Research Institute, Seoul (Korea, Republic of)

    2014-11-15

    To compare the pulmonary subsolid nodule (SSN) classification agreement and measurement variability between filtered back projection (FBP) and model-based iterative reconstruction (MBIR). Low-dose CTs were reconstructed using FBP and MBIR for 47 patients with 47 SSNs. Two readers independently classified SSNs into pure or part-solid ground-glass nodules, and measured the size of the whole nodule and solid portion twice on both reconstruction algorithms. Nodule classification agreement was analyzed using Cohen's kappa and compared between reconstruction algorithms using McNemar's test. Measurement variability was investigated using Bland-Altman analysis and compared with the paired t-test. Cohen's kappa for inter-reader SSN classification agreement was 0.541-0.662 on FBP and 0.778-0.866 on MBIR. Between the two readers, nodule classification was consistent in 79.8 % (75/94) with FBP and 91.5 % (86/94) with MBIR (p = 0.027). Inter-reader measurement variability range was -5.0-2.1 mm on FBP and -3.3-1.8 mm on MBIR for whole nodule size, and was -6.5-0.9 mm on FBP and -5.5-1.5 mm on MBIR for solid portion size. Inter-reader measurement differences were significantly smaller on MBIR (p = 0.027, whole nodule; p = 0.011, solid portion). MBIR significantly improved SSN classification agreement and reduced measurement variability of both whole nodules and solid portions between readers. (orig.)

  19. Data Assimilation to Improve CMAQ Model Estimates of Particulate Matter Pollution during Wintertime Persistent Cold Air Pool Events in Salt Lake City, Utah

    Science.gov (United States)

    Ivey, C. E.; Balachandran, S.; Russell, A. G.; Hu, Y.; Holmes, H.

    2017-12-01

    More than one million people live in Salt Lake Valley, Utah, where wintertime pollution reaches unhealthy levels due to the unique meteorology and orography of the region. Persistent cold air pool (PCAP) events occur when high pressure ridges create stagnant conditions over a valley, which hampers large-scale advection and reduces surface wind speeds. During PCAP periods the fraction of incoming solar radiation that reaches the valley floor is also reduced, leading to temperature inversions that allow pollution to build. Pollution levels continue to climb until a washout event removes the pollutants from the valley. Washout events include high winds or precipitation events with advection or wet deposition related removal processes, respectively. In this work, novel data assimilation and source apportionment techniques are applied for January and February 2007 to analyze CMAQ-modeled source composition and source impacts for the Salt Lake Valley during PCAP events. First, a hybrid source-oriented apportionment model is applied over continental U.S. to determine observation and model-based impacts from 20 sources, including agricultural activities, fossil fuel combustion, dust, and metals processing. Then, a secondary bias correction method is applied to better quantify the source impacts on secondary PM2.5, which constitutes the majority of the PM2.5 mass. Revised concentrations reflect what was previously reported in studies of PCAP pollution in the Salt Lake Valley, where the dominant aerosol was found to be ammonium nitrate. Further, gasoline and natural gas combustion were found to be the greatest contributing sources to aerosol concentrations during the PCAP events. The benefit of the data assimilation methods is the availability of spatially and temporally resolved model estimates of source impacts that better reflect observed concentrations.

  20. Persistent effect of mTOR inhibition on preneoplastic foci progression and gene expression in a rat model of hepatocellular carcinoma.

    Science.gov (United States)

    Francois-Vaughan, Heather; Adebayo, Adeola O; Brilliant, Kate E; Parry, Nicola M A; Gruppuso, Philip A; Sanders, Jennifer A

    2016-04-01

    Hepatocellular carcinoma (HCC) is a heterogeneous disease in which tumor subtypes can be identified based on the presence of adult liver progenitor cells. Having previously identified the mTOR pathway as critical to progenitor cell proliferation in a model of liver injury, we investigated the temporal activation of mTOR signaling in a rat model of hepatic carcinogenesis. The model employed chemical carcinogens and partial hepatectomy to induce progenitor marker-positive HCC. Immunohistochemical staining for phosphorylated ribosomal protein S6 indicated robust mTOR complex 1 (mTORC1) activity in early preneoplastic lesions that peaked during the first week and waned over the subsequent 10 days. Continuous administration of rapamycin by subcutaneous pellet for 70 days markedly reduced the development of focal lesions, but resulted in activation of the PI3K signaling pathway. To test the hypothesis that early mTORC1 activation was critical to the development and progression of preneoplastic foci, we limited rapamycin administration to the 3-week period at the start of the protocol. Focal lesion burden was reduced to a degree indistinguishable from that seen with continuous administration. Short-term rapamycin did not result in the activation of PI3K or mTORC2 pathways. Microarray analysis revealed a persistent effect of short-term mTORC1 inhibition on gene expression that resulted in a genetic signature reminiscent of normal liver. We conclude that mTORC1 activation during the early stages of hepatic carcinogenesis may be critical due to the development of preneoplastic focal lesions in progenitor marker-positive HCC. mTORC1 inhibition may represent an effective chemopreventive strategy for this form of liver cancer. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  1. Modeling persistent organic pollutant (POP) partitioning between tree bark and air and its application to spatial monitoring of atmospheric POPs in mainland China.

    Science.gov (United States)

    Zhao, Yuli; Yang, Limin; Wang, Qiuquan

    2008-08-15

    A mathematical model describing the bark/air partitioning of persistent organic pollutants (POPs) was established taking into consideration the accumulation processes of POPs from air into bark and compound-, species-, and site-specific air-to-bark accumulation factors. It allows the assessment of the concentrations of atmospheric POPs based on those recorded in tree bark. The spatial distribution of atmospheric POPs including 18 polycyclic aromatic hydrocarbons (Sigma18PAHs), 5 organic chlorinated pesticides (Sigma5OCPs), 10 polychlorinated biphenyls (Sigma10PCBs), and 17 brominated flame retardants (Sigma17BFRs) were investigated by analyzing 163 bark samples from 68 sites across mainland China. The atmospheric POPs were estimated to be 4.1-399 ng/m3 air, and 11.3-553, 4.5-130, and 0.9-624 pg/m3 air with geometric means of 71 ng/m3 air, and 99,26, and 25 pg/m3 airfor Sigma18PAHs, Sigma5OCPs, Sigma10PCBs, and Sigma17BFRs, respectively, based on those recorded in the tree barks of 5.1-1770, 0.05-12.9, 0.21-21.6, and 0.02-48.3 ng/g bark on dry weight basis, with geometric means of 295, 1.47, 3.12, and 2.79 ng/g bark. These results generally indicated that contamination by atmospheric POPs is more serious in eastern and mid China than that in western China.

  2. Selecting Cooking Methods to Decrease Persistent Organic Pollutant Concentrations in Food of Animal Origin Using a Consensus Decision-Making Model

    Directory of Open Access Journals (Sweden)

    Xiao Tan

    2017-02-01

    Full Text Available Persistent organic pollutants (POPs pose serious threats to human health. Increasing attention has been paid to POPs to protect the environment and prevent disease. Humans are exposed to POPs through diet (the major route, inhaling air and dust and skin contact. POPs are very lipophilic and hydrophobic, meaning that they accumulate in fatty tissues in animals and can biomagnify. Humans can therefore be exposed to relatively high POP concentrations in food of animal origin. Cooking animal products can decrease the POP contents, and different cooking methods achieve different reduction rates. Here, a consensus decision-making model with interval preference relations is used to prioritize cooking methods for specific animal products in terms of reducing POP concentrations. Two consistency mathematical expressions (I-consistency and I I -consistency are defined, then the ideal interval preference relations are determined for the cooking methods with respect to different social choice principles. The objective is to minimize disparities between individual judgments and the ideal consensus judgment. Consistency is used as a constraint to determine the rationality of the consistency definitions. A numerical example indicated that baking is the best cooking method for decreasing POP concentrations in grass carp. The I-consistency results were more acceptable than the I I -consistency results.

  3. Long memory and changing persistence

    DEFF Research Database (Denmark)

    Kruse, Robinson; Sibbertsen, Philipp

    We study the empirical behaviour of semi-parametric log-periodogram estimation for long memory models when the true process exhibits a change in persistence. Simulation results confirm theoretical arguments which suggest that evidence for long memory is likely to be found. A recently proposed test...... by Sibbertsen and Kruse (2009) is shown to exhibit noticeable power to discriminate between long memory and a structural change in autoregressive parameters....

  4. Persistent Authentication in Smart Environments

    DEFF Research Database (Denmark)

    Hansen, Mads Syska; Kirschmeyer, Martin; Jensen, Christian D.

    2008-01-01

    present a proof-of-concept implementation of the proposed mechanism, which employs camera based tracking with a single stationary 3D camera that uses the "time of flight" principle. A preliminary evaluation of the proposed mechanism indicates that persistent authentication is technically possible...... with the proposed hardware. The proposed model is sufficiently general to allow the addition of more cameras or supplemental tracking technologies, which will improve the robustness and scalability of the proposed mechanism....

  5. Radar interferometry persistent scatterer technique

    CERN Document Server

    Kampes, Bert M

    2014-01-01

    This volume is devoted to the Persistent Scatterer Technique, the latest development in radar interferometric data processing. It is the only book on Permanent Scatterer (PS) technique of radar interferometry, and it details a newly developed stochastic model and estimator algorithm to cope with possible problems for the application of the PS technique. The STUN (spatio-temporal unwrapping network) algorithm, developed to cope with these issues in a robust way, is presented and applied to two test sites.

  6. Examining the Effects of Stress and Campus Climate on the Persistence of Students of Color and White Students: An Application of Bean and Eaton's Psychological Model of Retention

    Science.gov (United States)

    Johnson, Dawn R.; Wasserman, Timothy H.; Yildirim, Nilay; Yonai, Barbara A.

    2014-01-01

    The current study examined the effects of stress and campus climate perceptions on the persistence decisions of students of color and White students using Bean and Eaton's (2000) Psychological Model of College Student Retention. A sample of first-year students (N = 1,491) at a predominantly White research university were survey enduring their…

  7. Forecasting autoregressive time series under changing persistence

    DEFF Research Database (Denmark)

    Kruse, Robinson

    Changing persistence in time series models means that a structural change from nonstationarity to stationarity or vice versa occurs over time. Such a change has important implications for forecasting, as negligence may lead to inaccurate model predictions. This paper derives generally applicable...... recommendations, no matter whether a change in persistence occurs or not. Seven different forecasting strategies based on a biasedcorrected estimator are compared by means of a large-scale Monte Carlo study. The results for decreasing and increasing persistence are highly asymmetric and new to the literature. Its...

  8. Persistence and clearance of Ebola virus RNA from seminal fluid of Ebola virus disease survivors: a longitudinal analysis and modelling study.

    Science.gov (United States)

    Sissoko, Daouda; Duraffour, Sophie; Kerber, Romy; Kolie, Jacques Seraphin; Beavogui, Abdoul Habib; Camara, Alseny-Modet; Colin, Géraldine; Rieger, Toni; Oestereich, Lisa; Pályi, Bernadett; Wurr, Stephanie; Guedj, Jeremie; Nguyen, Thi Huyen Tram; Eggo, Rosalind M; Watson, Conall H; Edmunds, W John; Bore, Joseph Akoi; Koundouno, Fara Raymond; Cabeza-Cabrerizo, Mar; Carter, Lisa L; Kafetzopoulou, Liana Eleni; Kuisma, Eeva; Michel, Janine; Patrono, Livia Victoria; Rickett, Natasha Y; Singethan, Katrin; Rudolf, Martin; Lander, Angelika; Pallasch, Elisa; Bockholt, Sabrina; Rodríguez, Estefanía; Di Caro, Antonino; Wölfel, Roman; Gabriel, Martin; Gurry, Céline; Formenty, Pierre; Keïta, Sakoba; Malvy, Denis; Carroll, Miles W; Anglaret, Xavier; Günther, Stephan

    2017-01-01

    By January, 2016, all known transmission chains of the Ebola virus disease (EVD) outbreak in west Africa had been stopped. However, there is concern about persistence of Ebola virus in the reproductive tract of men who have survived EVD. We aimed to use biostatistical modelling to describe the dynamics of Ebola virus RNA load in seminal fluid, including clearance parameters. In this longitudinal study, we recruited men who had been discharged from three Ebola treatment units in Guinea between January and July, 2015. Participants provided samples of seminal fluid at follow-up every 3-6 weeks, which we tested for Ebola virus RNA using quantitative real-time RT-PCR. Representative specimens from eight participants were then inoculated into immunodeficient mice to test for infectivity. We used a linear mixed-effect model to analyse the dynamics of virus persistence in seminal fluid over time. We enrolled 26 participants and tested 130 seminal fluid specimens; median follow up was 197 days (IQR 187-209 days) after enrolment, which corresponded to 255 days (228-287) after disease onset. Ebola virus RNA was detected in 86 semen specimens from 19 (73%) participants. Median duration of Ebola virus RNA detection was 158 days after onset (73-181; maximum 407 days at end of follow-up). Mathematical modelling of the quantitative time-series data showed a mean clearance rate of Ebola virus RNA from seminal fluid of -0·58 log units per month, although the clearance kinetic varied greatly between participants. Using our biostatistical model, we predict that 50% and 90% of male survivors clear Ebola virus RNA from seminal fluid at 115 days (90% prediction interval 72-160) and 294 days (212-399) after disease onset, respectively. We also predicted that the number of men positive for Ebola virus RNA in affected countries would decrease from about 50 in January 2016, to fewer than 1 person by July, 2016. Infectious virus was detected in 15 of 26 (58%) specimens tested in mice. Time

  9. Persistence in youth unemployment

    OpenAIRE

    Caporale, Guglielmo Maria; Gil-Alana, Luis A.

    2012-01-01

    This paper examines the degree of persistence of youth unemployment (total, male and female) in twenty-four countries by using two alternative measures: the AR coefficient and the fractional differencing parameter, based on short- and long-memory processes respectively. The evidence suggests that persistence is particularly high in Japan and some EU countries such as Spain, Portugal, Ireland and Finland, where appropriate policy actions are of the essence. Specifically, active labour market p...

  10. PACAP inhibits β-cell mass expansion in a mouse model of type II diabetes: persistent suppressive effects on islet density

    Directory of Open Access Journals (Sweden)

    Hiroaki eInoue

    2013-03-01

    Full Text Available Pituitary adenylate cyclase-activating polypeptide (PACAP is a potent insulinotropic G-protein-coupled receptor ligand, for which morphoregulative roles in pancreatic islets have recently been suggested. Here, we evaluated the effects of pancreatic overexpression of PACAP on morphometric changes of islets in a severe type II diabetes model. Following cross-breeding of obese-diabetic model KKAy mice with mice overexpressing PACAP in their pancreatic β-cells, the resulting KKAy mice with or without PACAP transgene (PACAP/+:Ay/+ or Ay/+ mice were fed with a high-fat diet up to the age of 11 months. Pancreatic sections from 5 and 11 month old littermates were examined. Histomorphometric analyses revealed significant suppression of islet mass expansion in PACAP/+:Ay/+ mice compared with Ay/+ mice at 11 months, but no significant difference between PACAP/+ and +/+ (wild-type mice, as previously reported. The suppressed islet mass in PACAP/+:Ay/+ mice was due to a decrease in islet density but not islet size. In addition, the density of tiny islets (<0.001 mm2 and of insulin-positive clusters in ductal structures were markedly decreased in PACAP/+:Ay/+ mice compared with Ay/+ mice at 5 months of age. In contrast, PACAP overexpression caused no significant effects on the level of aldehyde-fuchsin reagent staining (a measure of β-cell granulation or the volume and localization of glucagon-positive cells in the pancreas. These results support previously reported inhibitory effects of PACAP on pancreatic islet mass expansion, and suggest it has persistent suppressive effects on pancreatic islet density which may be related with ductal cell-associated islet neogenesis in type II diabetes.

  11. Factor structure and longitudinal measurement invariance of PHQ-9 for specialist mental health care patients with persistent major depressive disorder: Exploratory Structural Equation Modelling.

    Science.gov (United States)

    Guo, Boliang; Kaylor-Hughes, Catherine; Garland, Anne; Nixon, Neil; Sweeney, Tim; Simpson, Sandra; Dalgleish, Tim; Ramana, Rajini; Yang, Min; Morriss, Richard

    2017-09-01

    The Patient Health Questionnaire-9 (PHQ-9) is a widely used instrument for measuring levels of depression in patients in clinical practice and academic research; its factor structure has been investigated in various samples, with limited evidence of measurement equivalence/invariance (ME/I) but not in patients with more severe depression of long duration. This study aims to explore the factor structure of the PHQ-9 and the ME/I between treatment groups over time for these patients. 187 secondary care patients with persistent major depressive disorder (PMDD) were recruited to a randomised controlled trial (RCT) with allocation to either a specialist depression team arm or a general mental health arm; their PHQ-9 score was measured at baseline, 3, 6, 9 and 12 months. Exploratory Structural Equational Modelling (ESEM) was performed to examine the factor structure for this specific patient group. ME/I between treatment arm at and across follow-up time were further explored by means of multiple-group ESEM approach using the best-fitted factor structure. A two-factor structure was evidenced (somatic and affective factor). This two-factor structure had strong factorial invariance between the treatment groups at and across follow up times. Participants were largely white British in a RCT with 40% attrition potentially limiting the study's generalisability. Not all two-factor modelling criteria were met at every time-point. PHQ-9 has a two-factor structure for PMDD patients, with strong measurement invariance between treatment groups at and across follow-up time, demonstrating its validity for RCTs and prospective longitudinal studies in chronic moderate to severe depression. Copyright © 2017. Published by Elsevier B.V.

  12. Persistência na lactação para vacas da raça Holandesa criadas no Estado do Rio Grande do Sul via modelos de regressão aleatória Lactation persistency for Holstein cows raised in the State of Rio Grande do Sul using a random regression model

    Directory of Open Access Journals (Sweden)

    Cristian Kelen Pinto Dorneles

    2009-08-01

    Full Text Available Foram utilizados 21.702 registros de produção de leite no dia do controle de 2.429 vacas primíparas da raça Holandesa, filhas de 233 touros, coletados em 33 rebanhos do Estado do Rio Grande do Sul, entre 1992 e 2003, para estimar parâmetros genéticos, para três medidas de persistência (PS1, PS2 e PS3 e para a produção de leite até 305 dias (P305 de lactação. Os modelos de regressão aleatória ajustados aos controles leiteiros entre o sexto e o 300o dia de lactação incluíram o efeito de rebanho-ano-mês do controle, a idade da vaca ao parto e os parâmetros do polinômio de Legendre de ordem quatro, para modelar a curva média da produção de leite da população e os parâmetros do mesmo polinômio, para modelar os efeitos aleatórios genético-aditivo direto e de ambiente permanente. As estimativas de herdabilidade obtidas foram 0,05, 0,08 e 0,19, respectivamente, para PS1, PS2 e PS3 e 0,25, para P305 sugerindo a possibilidade de ganho genético por meio da seleção para PS3 e para P305. As correlações genéticas entre as três medidas de persistência e P305, variaram de -0,05 a 0,07, indicando serem persistência e produção, características determinadas por grupos de genes diferentes. Assim, consequentemente, a seleção para P305, geralmente praticada, não promove progresso genético para a persistência.There were used 21,702 test day milk yields from 2,429 first parity Holstein breed cows, daughters of 2,031 dams and 233 sires, distributed over 33 herds in the state of Rio Grande do Sul, from 1992 to 2003. Genetic parameters for three measures of lactation persistency (PS1, PS2 e PS3 and for milk production to 305 days (P305 were evaluated. A random regression model adjusted by fourth order Legendre polynomial was used. The random regression model adjusted to test day between the sixth and the 305th lactation day included the herd-year-season of the test day, the age of the cow at the parturition effects and the

  13. Occupancy modeling reveals territory-level effects of nest boxes on the presence, colonization, and persistence of a declining raptor in a fruit-growing region.

    Directory of Open Access Journals (Sweden)

    Megan E Shave

    Full Text Available Nest boxes for predators in agricultural regions are an easily implemented tool to improve local habitat quality with potential benefits for both conservation and agriculture. The potential for nest boxes to increase raptor populations in agricultural regions is of particular interest given their positions as top predators. This study examined the effects of cherry orchard nest boxes on the local breeding population of a declining species, the American Kestrel (Falco sparverius, in a fruit-growing region of Michigan. During the 2013-2016 study, we added a total of 23 new nest boxes in addition to 24 intact boxes installed previously; kestrels used up to 100% of our new boxes each season. We conducted temporally-replicated surveys along four roadside transects divided into 1.6 km × 500 m sites. We developed a multi-season occupancy model under a Bayesian framework and found that nest boxes had strong positive effects on first-year site occupancy, site colonization, and site persistence probabilities. The estimated number of occupied sites increased between 2013 and 2016, which correlated with the increase in number of sites with boxes. Kestrel detections decreased with survey date but were not affected by time of day or activity at the boxes themselves. These results indicate that nest boxes determined the presence of kestrels at our study sites and support the conclusion that the local kestrel population is likely limited by nest site availability. Furthermore, our results are highly relevant to the farmers on whose properties the boxes were installed, for we can conclude that installing a nest box in an orchard resulted in a high probability of kestrels occupying that orchard or the areas adjacent to it.

  14. Effects of Persistent Atrial Fibrillation-Induced Electrical Remodeling on Atrial Electro-Mechanics - Insights from a 3D Model of the Human Atria.

    Science.gov (United States)

    Adeniran, Ismail; MacIver, David H; Garratt, Clifford J; Ye, Jianqiao; Hancox, Jules C; Zhang, Henggui

    2015-01-01

    Atrial stunning, a loss of atrial mechanical contraction, can occur following a successful cardioversion. It is hypothesized that persistent atrial fibrillation-induced electrical remodeling (AFER) on atrial electrophysiology may be responsible for such impaired atrial mechanics. This simulation study aimed to investigate the effects of AFER on atrial electro-mechanics. A 3D electromechanical model of the human atria was developed to investigate the effects of AFER on atrial electro-mechanics. Simulations were carried out in 3 conditions for 4 states: (i) the control condition, representing the normal tissue (state 1) and the tissue 2-3 months after cardioversion (state 2) when the atrial tissue recovers its electrophysiological properties after completion of reverse electrophysiological remodelling; (ii) AFER-SR condition for AF-remodeled tissue with normal sinus rhythm (SR) (state 3); and (iii) AFER-AF condition for AF-remodeled tissue with re-entrant excitation waves (state 4). Our results indicate that at the cellular level, AFER (states 3 & 4) abbreviated action potentials and reduced the Ca2+ content in the sarcoplasmic reticulum, resulting in a reduced amplitude of the intracellular Ca2+ transient leading to decreased cell active force and cell shortening as compared to the control condition (states 1 & 2). Consequently at the whole organ level, atrial contraction in AFER-SR condition (state 3) was dramatically reduced. In the AFER-AF condition (state 4) atrial contraction was almost abolished. This study provides novel insights into understanding atrial electro-mechanics illustrating that AFER impairs atrial contraction due to reduced intracellular Ca2+ transients.

  15. Effects of Persistent Atrial Fibrillation-Induced Electrical Remodeling on Atrial Electro-Mechanics – Insights from a 3D Model of the Human Atria

    Science.gov (United States)

    Adeniran, Ismail; MacIver, David H.; Garratt, Clifford J.; Ye, Jianqiao; Hancox, Jules C.; Zhang, Henggui

    2015-01-01

    Aims Atrial stunning, a loss of atrial mechanical contraction, can occur following a successful cardioversion. It is hypothesized that persistent atrial fibrillation-induced electrical remodeling (AFER) on atrial electrophysiology may be responsible for such impaired atrial mechanics. This simulation study aimed to investigate the effects of AFER on atrial electro-mechanics. Methods and Results A 3D electromechanical model of the human atria was developed to investigate the effects of AFER on atrial electro-mechanics. Simulations were carried out in 3 conditions for 4 states: (i) the control condition, representing the normal tissue (state 1) and the tissue 2–3 months after cardioversion (state 2) when the atrial tissue recovers its electrophysiological properties after completion of reverse electrophysiological remodelling; (ii) AFER-SR condition for AF-remodeled tissue with normal sinus rhythm (SR) (state 3); and (iii) AFER-AF condition for AF-remodeled tissue with re-entrant excitation waves (state 4). Our results indicate that at the cellular level, AFER (states 3 & 4) abbreviated action potentials and reduced the Ca2+ content in the sarcoplasmic reticulum, resulting in a reduced amplitude of the intracellular Ca2+ transient leading to decreased cell active force and cell shortening as compared to the control condition (states 1 & 2). Consequently at the whole organ level, atrial contraction in AFER-SR condition (state 3) was dramatically reduced. In the AFER-AF condition (state 4) atrial contraction was almost abolished. Conclusions This study provides novel insights into understanding atrial electro-mechanics illustrating that AFER impairs atrial contraction due to reduced intracellular Ca2+ transients. PMID:26606047

  16. GEM/POPs: a global 3-D dynamic model for semi-volatile persistent organic pollutants ─ Part 2: Global transports and budgets of PCBs

    Directory of Open Access Journals (Sweden)

    L. A. Barrie

    2007-08-01

    Full Text Available Global transports and budgets of three PCBs were investigated with a 3-D dynamic model for semi-volatile persistent organic pollutants – GEM/POPs. Dominant pathways were identified for PCB transports in the atmosphere with a transport flux peaking below 8 km for gaseous and 14 km for particulate PCB28, and peaking below 4 km for gaseous and 6 km for particulate PCB180. The inter-continental transports of PCBs in the Northern Hemisphere (NH are dominated in the zonal direction with their route changes regulated seasonally by the variation of westerly jet. The transport pathways from Europe and North Atlantic contributed the most PCBs to the Arctic. Inter-hemispheric transports of PCBs originated from the regions of Europe, Asia and North America in three different flow-paths, accompanying with easterly jet, Asian monsoon winds and trade winds. PCBs from the Southern Hemisphere (SH could also be exported into the NH. According to the PCB emissions of year 2000, Europe, North America and Asia are the three largest sources of the three PCBs, contributing to the global background concentrations in the atmosphere, soil and water. Globally, PCB28 in soil and water has become a comparable source to the anthropogenic emissions while heavier PCBs such as PCB153 and 180 are still transporting into soil and water. For all three congeners, particulate PCBs are concentrated in the higher levels than gaseous PCBs. More than half of the particulate PCB28 could reach up to the stratosphere, while most of the heavier counter-parts (PCB153 and PCB180 are stored in the troposphere including boundary layer with more than 99% gaseous PCB180 below 6 km.

  17. Persistent and recurrent hyperparathyroidism.

    Science.gov (United States)

    Guerin, Carole; Paladino, Nunzia Cinzia; Lowery, Aoife; Castinetti, Fréderic; Taieb, David; Sebag, Fréderic

    2017-06-01

    Despite remarkable progress in imaging modalities and surgical management, persistence or recurrence of primary hyperparathyroidism (PHPT) still occurs in 2.5-5% of cases of PHPT. The aim of this review is to expose the management of persistent and recurrent hyperparathyroidism. A literature search was performed on MEDLINE using the search terms "recurrent" or "persistent" and "hyperparathyroidism" within the past 10 years. We also searched the reference lists of articles identified by this search strategy and selected those we judged relevant. Before considering reoperation, the surgeon must confirm the diagnosis of PHPT. Then, the patient must be evaluated with new imaging modalities. A single adenoma is found in 68% of cases, multiglandular disease in 28%, and parathyroid carcinoma in 3%. Others causes (<1%) include parathyromatosis and graft recurrence. The surgeon must balance the benefits against the risks of a reoperation (permanent hypocalcemia and recurrent laryngeal nerve palsy). If surgery is necessary, a focused approach can be considered in cases of significant imaging foci, but in the case of multiglandular disease, a bilateral neck exploration could be necessary. Patients with multiple endocrine neoplasia syndromes are at high risk of recurrence and should be managed regarding their hereditary pathology. The cure rate of persistent-PHPT or recurrent-PHPT in expert centers is estimated from 93 to 97%. After confirming the diagnosis of PHPT, patients with persistent-PHPT and recurrent-PHPT should be managed in an expert center with all dedicated competencies.

  18. Defining persistent hotspots

    DEFF Research Database (Denmark)

    Kittur, Nupur; Binder, Sue; Campbell, Carl H.

    2017-01-01

    , investigators and neglected tropical disease (NTD) program managers need to define them based on changes in prevalence and/or intensity. But how should the data be analyzed to define a persistent hotspot? We have analyzed a dataset from an operational research study in western Tanzania after three annual MDAs...... and contrast the outcomes of these analyses. Our intent is to showhowthe samedataset yields different numbers of persistent hotspots depending on the approach used to define them. We suggest that investigators and NTD program managers use the approach most suited for their study or program, but whichever...... using four different approaches to define persistent hotspots. The four approaches are 1) absolute percent change in prevalence; 2) percent change in prevalence; 3) change in World Health Organization guideline categories; 4) change (absolute or percent) in both prevalence and intensity. We compare...

  19. Persistent luminescence nanothermometers

    Science.gov (United States)

    Martín Rodríguez, Emma; López-Peña, Gabriel; Montes, Eduardo; Lifante, Ginés; García Solé, José; Jaque, Daniel; Diaz-Torres, Luis Armando; Salas, Pedro

    2017-08-01

    Persistent phosphorescence nanoparticles emitting in the red and near-infrared spectral regions are strongly demanded as contrast nanoprobes for autofluorescence free bioimaging and biosensing. In this work, we have developed Sr4Al14O25:Eu2+, Cr3+, Nd3+ nanopowders that produce persistent red phosphorescence peaking at 694 nm generated by Cr3+ ions. This emission displays temperature sensitivity in the physiological temperature range (20-60 °C), which makes these nanoparticles potentially useful as fluorescence (contactless) nanothermometers operating without requiring optical excitation. Nd3+ ions, which act as shallow electron traps for the red Cr3+ persistent emission, also display infrared emission bands, extending the fluorescence imaging capability to the second biological window. This unique combination of properties makes these nanoparticles multifunctional luminescent probes with great potential applications in nanomedicine.

  20. A SIMPLE EVOLUTIONAL MODEL OF THE UV HABITABLE ZONE AND THE POSSIBILITY OF PERSISTENT LIFE EXISTENCE: THE EFFECTS OF MASS AND METALLICITY

    Energy Technology Data Exchange (ETDEWEB)

    Oishi, Midori; Kamaya, Hideyuki [Department of Earth and Ocean Sciences, School of Applied Sciences, National Defense Academy of Japan Yokosuka, 239-8686 (Japan)

    2016-12-20

    In addition to the habitable zone (HZ), the UV habitable zone (UV-HZ) is important when considering the existence of persistent life in the universe. The UV-HZ is defined as the area where the UV radiation field from a host star is moderate for persistent life existence. This is because UV is necessary for the synthesis of biochemical compounds. The UV-HZ must overlap the HZ when life appears and evolves. In this paper, following our previous study of the HZ, we examine the UV-HZ in cases with a stellar mass range from 0.08 to 4.00 M {sub ☉} with various metallicities during the main sequence phase. This mass range was chosen because we are interested in an environment similar to that of Earth. The effect of metallicity is reflected in the spectrum of the host stars, and we reexamine it in the context of the UV-HZ. The present work shows the effect of metallicity when that in the UV-HZ is less than that in the HZ. Furthermore, we find that the chance of persistent life existence declines as the metallicity decreases, as long as the UV radiation is not protected and/or boosted by any mechanisms. This is because the overlapped region of a persistent HZ and UV-HZ decreases. We find that the most appropriate stellar mass for the persistence of life existence is from 1.0 to 1.5 M {sub ☉} with metallicity Z  = 0.02, and only about 1.2 M {sub ☉} with Z  = 0.002. When Z  = 0.0002, the chance of persistent life existence is very low, assuming that the ocean does not protect the life from UV radiation.

  1. Archaeal Persisters: Persister Cell Formation as a Stress Response in Haloferax volcanii

    Directory of Open Access Journals (Sweden)

    Julianne Megaw

    2017-08-01

    Full Text Available Persister cells are phenotypic variants within a microbial population, which are dormant and transiently tolerant to stress. Persistence has been studied extensively in bacteria, and in eukaryotes to a limited extent, however, it has never been observed in archaea. Using the model haloarchaeon, Haloferax volcanii DS2, we demonstrated persister cell formation in this domain, with time-kill curves exhibiting a characteristic biphasic pattern following starvation or exposure to lethal concentrations of various biocidal compounds. Repeated challenges of surviving cells showed that, as with bacteria, persister formation in H. volcanii was not heritable. Additionally, as previously shown with bacteria, persister formation in H. volcanii was suppressed by exogenous indole. The addition of spent culture media to assays conducted on planktonic cells showed that H. volcanii-conditioned media stimulated persistence, whereas conditioned media of other haloarchaea or halophilic bacteria did not, suggesting the involvement of a species-specific signal. Using a TLC overlay assay, the quorum sensing bioreporter Agrobacterium tumefaciens ATCC BAA-2240 detected the presence of C4 and C6 acyl homoserine lactone-like signal molecules in a H. volcanii culture extract. While synthetic bacterial AHLs did not induce persistence, this is potentially due to structural differences between bacterial and archaeal signals, and does not discount a quorum sensing component in haloarchaeal persister formation. The observation of persister cell formation by this haloarchaeon may provide some insights into the survival of these organisms in stressful or dynamic environments.

  2. Contributions to Persistence Theory

    Directory of Open Access Journals (Sweden)

    Du Dong

    2014-12-01

    Full Text Available Persistence theory discussed in this paper is an application of algebraic topology (Morse Theory [29] to Data Analysis, precisely to qualitative understanding of point cloud data, or PCD for short. PCD can be geometrized as a filtration of simplicial complexes (Vietoris-Rips complex [25] [36] and the homology changes of these complexes provide qualitative information about the data. Bar codes describe the changes in homology with coefficients in a fixed field. When the coefficient field is ℤ2, the calculation of bar codes is done by ELZ algorithm (named after H. Edelsbrunner, D. Letscher, and A. Zomorodian [20]. When the coefficient field is ℝ, we propose an algorithm based on the Hodge decomposition [17]. With Dan Burghelea and Tamal K. Dey we developed a persistence theory which involves level sets discussed in Section 4. We introduce and discuss new computable invariants, the “relevant level persistence numbers” and the “positive and negative bar codes”, and explain how they are related to the bar codes for level persistence. We provide enhancements and modifications of ELZ algorithm to calculate such invariants and illustrate them by examples.

  3. Persistent organic pollutants

    NARCIS (Netherlands)

    Dungen, van den M.W.

    2016-01-01

    Wild caught fish, especially marine fish, can contain high levels of persistent organic pollutants (POPs). In the Netherlands, especially eel from the main rivers have high POP levels. This led to a ban in 2011 on eel fishing due to health concerns. Many of the marine POPs have been related to

  4. Persistent organic pollutants

    NARCIS (Netherlands)

    Dungen, van den M.W.

    2016-01-01

    Wild caught fish, especially marine fish, can contain high levels of persistent organic pollutants (POPs). In the Netherlands, especially eel from the main rivers have high POP levels. This led to a ban in 2011 on eel fishing due to health concerns. Many of the marine POPs have been related to

  5. Is corruption really persistent?

    NARCIS (Netherlands)

    Seldadyo, H.; de Haan, J.

    Theoretical and empirical research on corruption generally concludes that corruption is persistent. However, using International Country Risk Guide data for the period 1984-2008 for 101 countries, we find strong evidence that corruption changes over time. In the present study, corruption levels of

  6. A Structural Examination of Academic Integration, Perceived Stress, Academic Performance, and Goal Commitment from an Elaborated Model of Adult Student Persistence.

    Science.gov (United States)

    Sandler, Martin E.

    The effects of selected variables on the academic persistence of adult students were examined in a study of a random sample of 469 adult students aged 24 years or older enrolled in a four-year college. The survey questionnaire, the Adult Student Experiences Survey, collected data regarding 12 endogenous variables and 13 exogenous variables…

  7. Examining the Relationship between Minority Status Stress, the Social Change Model of Leadership Development, and Persistence of Black Students at Predominantly White Institutions

    Science.gov (United States)

    Brown, Lesley-Ann

    2012-01-01

    Minority status stress, which is the stress Black college students experience at predominantly White institutions (PWIs) as a result of their racial minority status, has been found to negatively impact their persistence in college. Two manuscripts were developed for this dissertation. The first is a critical literature review which establishes the…

  8. Virtual In-Silico Modeling Guided Catheter Ablation Predicts Effective Linear Ablation Lesion Set for Longstanding Persistent Atrial Fibrillation: Multicenter Prospective Randomized Study.

    Science.gov (United States)

    Shim, Jaemin; Hwang, Minki; Song, Jun-Seop; Lim, Byounghyun; Kim, Tae-Hoon; Joung, Boyoung; Kim, Sung-Hwan; Oh, Yong-Seog; Nam, Gi-Byung; On, Young Keun; Oh, Seil; Kim, Young-Hoon; Pak, Hui-Nam

    2017-01-01

    Objective: Radiofrequency catheter ablation for persistent atrial fibrillation (PeAF) still has a substantial recurrence rate. This study aims to investigate whether an AF ablation lesion set chosen using in-silico ablation (V-ABL) is clinically feasible and more effective than an empirically chosen ablation lesion set (Em-ABL) in patients with PeAF. Methods: We prospectively included 108 patients with antiarrhythmic drug-resistant PeAF (77.8% men, age 60.8 ± 9.9 years), and randomly assigned them to the V-ABL ( n = 53) and Em-ABL ( n = 55) groups. Five different in-silico ablation lesion sets [1 pulmonary vein isolation (PVI), 3 linear ablations, and 1 electrogram-guided ablation] were compared using heart-CT integrated AF modeling. We evaluated the feasibility, safety, and efficacy of V-ABL compared with that of Em-ABL. Results: The pre-procedural computing time for five different ablation strategies was 166 ± 11 min. In the Em-ABL group, the earliest terminating blinded in-silico lesion set matched with the Em-ABL lesion set in 21.8%. V-ABL was not inferior to Em-ABL in terms of procedure time ( p = 0.403), ablation time ( p = 0.510), and major complication rate ( p = 0.900). During 12.6 ± 3.8 months of follow-up, the clinical recurrence rate was 14.0% in the V-ABL group and 18.9% in the Em-ABL group ( p = 0.538). In Em-ABL group, clinical recurrence rate was significantly lower after PVI+posterior box+anterior linear ablation, which showed the most frequent termination during in-silico ablation (log-rank p = 0.027). Conclusions: V-ABL was feasible in clinical practice, not inferior to Em-ABL, and predicts the most effective ablation lesion set in patients who underwent PeAF ablation.

  9. Persistent physical symptoms as perceptual dysregulation

    DEFF Research Database (Denmark)

    Henningsen, Peter; Gündel, Harald; Kop, Willem J

    2018-01-01

    OBJECTIVE: The mechanisms underlying the perception and experience of persistent physical symptoms are not well understood, and in the models, the specific relevance of peripheral input versus central processing, or of neurobiological versus psychosocial factors in general, is not clear.In this a......OBJECTIVE: The mechanisms underlying the perception and experience of persistent physical symptoms are not well understood, and in the models, the specific relevance of peripheral input versus central processing, or of neurobiological versus psychosocial factors in general, is not clear...... of predictions and sensory input. Two possibilities exist: adaptation of the generative model underlying the predictions or alteration of the sensory input via autonomic nervous activation (in the case of interoception). Following this model, persistent physical symptoms can be described as "failures...

  10. Persistent insomnia is associated with mortality risk.

    Science.gov (United States)

    Parthasarathy, Sairam; Vasquez, Monica M; Halonen, Marilyn; Bootzin, Richard; Quan, Stuart F; Martinez, Fernando D; Guerra, Stefano

    2015-03-01

    Insomnia has been associated with mortality risk, but whether this association is different in subjects with persistent vs intermittent insomnia is unclear. Additionally, the role of systemic inflammation in such an association is unknown. We used data from a community-based cohort to determine whether persistent or intermittent insomnia, defined based on persistence of symptoms over a 6-year period, was associated with death during the following 20 years of follow-up. We also determined whether changes in serum C-reactive protein (CRP) levels measured over 2 decades between study initiation and insomnia determination were different for the persistent, intermittent, and never insomnia groups. The results were adjusted for confounders such as age, sex, body mass index, smoking, physical activity, alcohol, and sedatives. Of the 1409 adult participants, 249 (18%) had intermittent and 128 (9%) had persistent insomnia. During a 20-year follow-up period, 318 participants died (118 due to cardiopulmonary disease). In adjusted Cox proportional-hazards models, participants with persistent insomnia (adjusted hazards ratio [HR] 1.58; 95% confidence interval [CI], 1.02-2.45) but not intermittent insomnia (HR 1.22; 95% CI, 0.86-1.74) were more likely to die than participants without insomnia. Serum CRP levels were higher and increased at a steeper rate in subjects with persistent insomnia as compared with intermittent (P = .04) or never (P = .004) insomnia. Although CRP levels were themselves associated with increased mortality (adjusted HR 1.36; 95% CI, 1.01-1.82; P = .04), adjustment for CRP levels did not notably change the association between persistent insomnia and mortality. In a population-based cohort, persistent, and not intermittent, insomnia was associated with increased risk for all-cause and cardiopulmonary mortality and was associated with a steeper increase in inflammation. Copyright © 2015 Elsevier Inc. All rights reserved.

  11. Persistent facial pain conditions

    DEFF Research Database (Denmark)

    Forssell, Heli; Alstergren, Per; Bakke, Merete

    2016-01-01

    Persistent facial pains, especially temporomandibular disorders (TMD), are common conditions. As dentists are responsible for the treatment of most of these disorders, up-to date knowledge on the latest advances in the field is essential for successful diagnosis and management. The review covers...... TMD, and different neuropathic or putative neuropathic facial pains such as persistent idiopathic facial pain and atypical odontalgia, trigeminal neuralgia and painful posttraumatic trigeminal neuropathy. The article presents an overview of TMD pain as a biopsychosocial condition, its prevalence......, clinical features, consequences, central and peripheral mechanisms, diagnostic criteria (DC/TMD), and principles of management. For each of the neuropathic facial pain entities, the definitions, prevalence, clinical features, and diagnostics are described. The current understanding of the pathophysiology...

  12. Persistent Hiccups Following Stapedectomy

    Directory of Open Access Journals (Sweden)

    Aidonis I

    2010-10-01

    Full Text Available Objective: We report a case of a 37 year-old man who developed persistent hiccups after elective stapedectomy. Method and Results: The diagnostic approach is discussed as well as the non-pharmacologic and pharmacologic treatments and overall management. The aim is to stress that there is a variety of potential factors that can induce hiccups perioperatively and in cases like this a step by step approach must be taken. Conclusion: Persistent hiccups are very rare following stapedectomy, control of them is crucial for the successful outcome. The trigger may be more than one factors and the good response to treatment may be due to dealing successfully with more than one thing.

  13. Persistent misconceptions regarding SERS.

    Science.gov (United States)

    Moskovits, Martin

    2013-04-21

    SERS is some 35 years old, and the subject of over 11 000 articles. The field of Plasmonics, and large aspects of Metamaterials are clearly based on concepts that became current as a result of SERS. Despite this, a number of persistent, fuzzy ideas about the origin of the enhancement in SERS continue to be current even among SERS researchers, leading to the external impression that SERS is uniquely poorly understood. Six such ideas are discussed.

  14. PCR-based detection of bacterial DNA after antimicrobial treatment is indicative of persistent, viable bacteria in the chinchilla model of otitis media.

    Science.gov (United States)

    Post, J C; Aul, J J; White, G J; Wadowsky, R M; Zavoral, T; Tabari, R; Kerber, B; Doyle, W J; Ehrlich, G D

    1996-01-01

    Bacterial deoxyribonucleic acid (DNA) has been previously detected by polymerase chain reactions (PCR) in a significant percentage of culturally-sterile pediatric middle-ear effusions. The current study was designed to determine whether this represents the existence of viable bacteria or the persistence of residual DNA in the middle-ear cleft. The middle-ear cavities of two sets of chinchillas were inoculated with either: 1) 100 colony-forming units (CFU) of live Haemophilus influenzae, 2.2 x 10(6) CFU of pasteurized Moraxella catarrhalis, and 1000 ng of DNA (>10(8) genomic equivalents) from Streptococcus pneumoniae; or 2) 100 CFU of live S pneumoniae, 2.2 x 10(6) CFU of pasteurized M catarrhalis and 1000 ng of purified DNA from H influenzae. Animals were treated with ampicillin for 5 days beginning on day 3. A single-point longitudinal study design was used for sampling to eliminate the possibility of contamination. No DNA was detectable from the heat-killed bacteria or the purified DNA after day 3. However, DNA from the live bacteria persisted through day 21, even though all specimens were culture-negative following the initiation of antimicrobial therapy. These findings indicate that purified DNA and DNA from intact but nonviable bacteria do not persist in the middle-ear cleft in the presence of an effusion, even following high copy inoculation. In contrast, antibiotic-treated bacteria persist in some viable state for weeks as evidenced by the differential ability of the PCR-based assay systems to detect the live bacteria, but not detect the heat-killed organisms.

  15. Numeric invariants from multidimensional persistence

    Energy Technology Data Exchange (ETDEWEB)

    Skryzalin, Jacek [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Carlsson, Gunnar [Stanford Univ., Stanford, CA (United States)

    2017-05-19

    In this paper, we analyze the space of multidimensional persistence modules from the perspectives of algebraic geometry. We first build a moduli space of a certain subclass of easily analyzed multidimensional persistence modules, which we construct specifically to capture much of the information which can be gained by using multidimensional persistence over one-dimensional persistence. We argue that the global sections of this space provide interesting numeric invariants when evaluated against our subclass of multidimensional persistence modules. Lastly, we extend these global sections to the space of all multidimensional persistence modules and discuss how the resulting numeric invariants might be used to study data.

  16. IL-17A and serum amyloid A are elevated in a cigarette smoke cessation model associated with the persistence of pigmented macrophages, neutrophils and activated NK cells.

    Directory of Open Access Journals (Sweden)

    Michelle J Hansen

    Full Text Available While global success in cessation advocacy has seen smoking rates fall in many developed countries, persistent lung inflammation in ex-smokers is an increasingly important clinical problem whose mechanistic basis remains poorly understood. In this study, candidate effector mechanisms were assessed in mice exposed to cigarette smoke (CS for 4 months following cessation from long term CS exposure. BALF neutrophils, CD4+ and CD8+ T cells and lung innate NK cells remained significantly elevated following smoking cessation. Analysis of neutrophil mobilization markers showed a transition from acute mediators (MIP-2α, KC and G-CSF to sustained drivers of neutrophil and macrophage recruitment and activation (IL-17A and Serum Amyoid A (SAA. Follicle-like lymphoid aggregates formed with CS exposure and persisted with cessation, where they were in close anatomical proximity to pigmented macrophages, whose number actually increased 3-fold following CS cessation. This was associated with the elastolytic protease, MMP-12 (macrophage metallo-elastase which remained significantly elevated post-cessation. Both GM-CSF and CSF-1 were significantly increased in the CS cessation group relative to the control group. In conclusion, we show that smoking cessation mediates a transition to accumulation of pigmented macrophages, which may contribute to the expanded macrophage population observed in COPD. These macrophages together with IL-17A, SAA and innate NK cells are identified here as candidate persistence determinants and, we suggest, may represent specific targets for therapies directed towards the amelioration of chronic airway inflammation.

  17. Persistent homology and string vacua

    Energy Technology Data Exchange (ETDEWEB)

    Cirafici, Michele [Center for Mathematical Analysis, Geometry and Dynamical Systems,Instituto Superior Técnico, Universidade de Lisboa,Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Institut des Hautes Études Scientifiques,Le Bois-Marie, 35 route de Chartres, F-91440 Bures-sur-Yvette (France)

    2016-03-08

    We use methods from topological data analysis to study the topological features of certain distributions of string vacua. Topological data analysis is a multi-scale approach used to analyze the topological features of a dataset by identifying which homological characteristics persist over a long range of scales. We apply these techniques in several contexts. We analyze N=2 vacua by focusing on certain distributions of Calabi-Yau varieties and Landau-Ginzburg models. We then turn to flux compactifications and discuss how we can use topological data analysis to extract physical information. Finally we apply these techniques to certain phenomenologically realistic heterotic models. We discuss the possibility of characterizing string vacua using the topological properties of their distributions.

  18. Poverty persistence and poverty dynamics

    OpenAIRE

    Martin Biewen

    2014-01-01

    A considerable part of the poverty that is measured in a single period is transitory rather than persistent. In most countries, only a portion of people who are currently poor are persistently poor. People who are persistently poor or who cycle into and out of poverty should be the main focus of anti-poverty policies. Understanding the characteristics of the persistently poor, and the circumstances and mechanisms associated with entry into and exit from poverty, can help to inform governments...

  19. Mindfulness Based Functional Therapy: A preliminary open trial of an integrated model of care for people with persistent low back pain.

    Directory of Open Access Journals (Sweden)

    Robert eSchutze

    2014-08-01

    Full Text Available Objectives: This pilot study investigated the feasibility and clinical utility of implementing a novel, evidence-informed, interdisciplinary group intervention – Mindfulness Based Functional Therapy (MBFT – for the management of persistent low back pain (LBP in primary care. MBFT aimed to improve physical and psychological functioning in patients with persistent LBP. Design: A single-group repeated measures design was utilized to gather data about feasibility, effect sizes, clinically significant changes and patient satisfaction.Setting: A community sample of 16 adults (75% female, mean (SD age 47.00 (9.12 years (range 26-65 years, with mean (SD LBP duration of 8.00 (9.00 years participated, using a simulated primary care setting at Curtin University in Australia.Intervention: MBFT is an 8-week group intervention co-facilitated by psychology and physiotherapy disciplines. Content includes: mindfulness meditation training, cognitive-functional physiotherapeutic movement retraining, pain education, and group support.Main outcome measures: Several validated self-report measures were used to assess functional disability, emotional functioning, mindfulness, pain catastrophizing, health-related quality of life at baseline, post-intervention, and 6 months follow-up.Results: Adherence and satisfaction was high, with 85% of participants highly satisfied with MBFT. Clinical significance analysis and effect size estimates showed improvements in a number of variables, including pain catastrophizing, physical functioning, role limitations due to physical condition, and depression, although these may have occurred due to non-intervention effects. Conclusions: MBFT is feasible to implement in primary care. Preliminary findings suggest that a randomized controlled trial is warranted to investigate its efficacy in improving physical and emotional functioning in people with disabling persistent LBP.

  20. Persistent marine debris

    International Nuclear Information System (INIS)

    Levy, E.M.

    1992-01-01

    In this paper the distribution of persistent marine debris, adrift on world oceans and stranded on beaches globally, is reviewed and related to the known inputs and transport by the major surface currents. Since naturally occurring processes eventually degrade petroleum in the environment, international measures to reduce the inputs have been largely successful in alleviating oil pollution on a global, if not on a local, scale. Many plastics, however, are so resistant to natural degradation that merely controlling inputs will be insufficient, and more drastic and costly measures will be needed to cope with the emerging global problem posed by these materials

  1. Handwashing and Ebola virus disease outbreaks: A randomized comparison of soap, hand sanitizer, and 0.05% chlorine solutions on the inactivation and removal of model organisms Phi6 and E. coli from hands and persistence in rinse water.

    Directory of Open Access Journals (Sweden)

    Marlene K Wolfe

    Full Text Available To prevent Ebola transmission, frequent handwashing is recommended in Ebola Treatment Units and communities. However, little is known about which handwashing protocol is most efficacious. We evaluated six handwashing protocols (soap and water, alcohol-based hand sanitizer (ABHS, and 0.05% sodium dichloroisocyanurate, high-test hypochlorite, and stabilized and non-stabilized sodium hypochlorite solutions for 1 efficacy of handwashing on the removal and inactivation of non-pathogenic model organisms and, 2 persistence of organisms in rinse water. Model organisms E. coli and bacteriophage Phi6 were used to evaluate handwashing with and without organic load added to simulate bodily fluids. Hands were inoculated with test organisms, washed, and rinsed using a glove juice method to retrieve remaining organisms. Impact was estimated by comparing the log reduction in organisms after handwashing to the log reduction without handwashing. Rinse water was collected to test for persistence of organisms. Handwashing resulted in a 1.94-3.01 log reduction in E. coli concentration without, and 2.18-3.34 with, soil load; and a 2.44-3.06 log reduction in Phi6 without, and 2.71-3.69 with, soil load. HTH performed most consistently well, with significantly greater log reductions than other handwashing protocols in three models. However, the magnitude of handwashing efficacy differences was small, suggesting protocols are similarly efficacious. Rinse water demonstrated a 0.28-4.77 log reduction in remaining E. coli without, and 0.21-4.49 with, soil load and a 1.26-2.02 log reduction in Phi6 without, and 1.30-2.20 with, soil load. Chlorine resulted in significantly less persistence of E. coli in both conditions and Phi6 without soil load in rinse water (p<0.001. Thus, chlorine-based methods may offer a benefit of reducing persistence in rinse water. We recommend responders use the most practical handwashing method to ensure hand hygiene in Ebola contexts, considering

  2. Handwashing and Ebola virus disease outbreaks: A randomized comparison of soap, hand sanitizer, and 0.05% chlorine solutions on the inactivation and removal of model organisms Phi6 and E. coli from hands and persistence in rinse water.

    Science.gov (United States)

    Wolfe, Marlene K; Gallandat, Karin; Daniels, Kyle; Desmarais, Anne Marie; Scheinman, Pamela; Lantagne, Daniele

    2017-01-01

    To prevent Ebola transmission, frequent handwashing is recommended in Ebola Treatment Units and communities. However, little is known about which handwashing protocol is most efficacious. We evaluated six handwashing protocols (soap and water, alcohol-based hand sanitizer (ABHS), and 0.05% sodium dichloroisocyanurate, high-test hypochlorite, and stabilized and non-stabilized sodium hypochlorite solutions) for 1) efficacy of handwashing on the removal and inactivation of non-pathogenic model organisms and, 2) persistence of organisms in rinse water. Model organisms E. coli and bacteriophage Phi6 were used to evaluate handwashing with and without organic load added to simulate bodily fluids. Hands were inoculated with test organisms, washed, and rinsed using a glove juice method to retrieve remaining organisms. Impact was estimated by comparing the log reduction in organisms after handwashing to the log reduction without handwashing. Rinse water was collected to test for persistence of organisms. Handwashing resulted in a 1.94-3.01 log reduction in E. coli concentration without, and 2.18-3.34 with, soil load; and a 2.44-3.06 log reduction in Phi6 without, and 2.71-3.69 with, soil load. HTH performed most consistently well, with significantly greater log reductions than other handwashing protocols in three models. However, the magnitude of handwashing efficacy differences was small, suggesting protocols are similarly efficacious. Rinse water demonstrated a 0.28-4.77 log reduction in remaining E. coli without, and 0.21-4.49 with, soil load and a 1.26-2.02 log reduction in Phi6 without, and 1.30-2.20 with, soil load. Chlorine resulted in significantly less persistence of E. coli in both conditions and Phi6 without soil load in rinse water (p<0.001). Thus, chlorine-based methods may offer a benefit of reducing persistence in rinse water. We recommend responders use the most practical handwashing method to ensure hand hygiene in Ebola contexts, considering the potential

  3. Diabetes medication persistence, different medications have different persistence rates.

    Science.gov (United States)

    Shani, Michal; Lustman, Alex; Vinker, Shlomo

    2017-08-01

    To assess the persistence of diabetic patients to oral medications. The study included all type 2 diabetic patients over 40 years, members of one District of Clalit Health Services Israel, who were diagnosed with diabetes mellitus before 2008 and who filled at least one prescription per year during 2008-2010, for the following medications: metformin, glibenclamide, acarbose, statins, angiotensin converting enzyme inhibitors (ACEI) and angiotensin II receptor antagonists (ARBs). Purchase of at least 9 monthly prescriptions during 2009 was considered "good medication persistence". We compared HbA1c and LDL levels, according to medication persistence, for each medication; and cross persistence rates between medications. 21,357 patients were included. Average age was 67.0±11.0years, 48.9% were men, and 35.8% were from low SES. Good medication persistence rates for ARBs were 78.8%, ACEI 69.0%, statins 66.6%, acarbose 67.8%, metformin 58.6%, and glibenclamide 55.3%. Good persistence to any of the medications tested was associated with a higher rate of good persistence to other medications. Patients who took more medications had better persistence rates. Different oral medications used by diabetic patients have different persistence rates. Good persistence for any one medication is an indicator of good persistence to other medications. Investment in enhancing medication persistence in persons with diabetes may improve persistence to other medications, as well as improve glycemic control. Copyright © 2017 Primary Care Diabetes Europe. Published by Elsevier Ltd. All rights reserved.

  4. A meta-analysis of the antiviral activity of the HBV-specific immunotherapeutic TG1050 confirms its value over a wide range of HBsAg levels in a persistent HBV pre-clinical model.

    Science.gov (United States)

    Kratzer, Roland; Sansas, Benoît; Lélu, Karine; Evlachev, Alexei; Schmitt, Doris; Silvestre, Nathalie; Inchauspé, Geneviève; Martin, Perrine

    2018-02-01

    Pre-clinical models mimicking persistent hepatitis B virus (HBV) expression are seldom, do not capture all features of a human chronic infection and due to their complexity, are subject to variability. We report a meta-analysis of seven experiments performed with TG1050, an HBV-targeted immunotherapeutic, 1 in an HBV-persistent mouse model based on the transduction of mice by an adeno-associated virus coding for an infectious HBV genome (AAV-HBV). To mimic the clinical diversity seen in HBV chronically infected patients, AAV-HBV transduced mice displaying variable HBsAg levels were treated with TG1050. Overall mean percentages of responder mice, displaying decrease in important clinical parameters i.e. HBV-DNA (viremia) and HBsAg levels, were 52% and 51% in TG1050 treated mice, compared with 8% and 22%, respectively, in untreated mice. No significant impact of HBsAg level at baseline on response to TG1050 treatment was found. TG1050-treated mice displayed a significant shorter Time to Response (decline in viral parameters) with an Hazard Ratio (HR) of 8.3 for viremia and 2.6 for serum HBsAg. The mean predicted decrease for TG1050-treated mice was 0.5 log for viremia and 0.8 log for HBsAg, at the end of mice follow-up, compared to no decrease for viremia and 0.3 log HBsAg decrease for untreated mice. For mice receiving TG1050, a higher decline of circulating viremia and serum HBsAg level over time was detected by interaction term meta-analysis with a significant treatment effect (p = 0.002 and pHBV-persistent model mimicking clinical situations.

  5. Caliber-Persistent Artery

    Directory of Open Access Journals (Sweden)

    Sabrina Araújo Pinho Costa

    2015-01-01

    Full Text Available Caliber-persistent artery (CPLA of the lip is a common vascular anomaly in which a main arterial branch extends to the surface of the mucous tissue with no reduction in its diameter. It usually manifests as pulsatile papule, is easily misdiagnosed, and is observed more frequently among older people, suggesting that its development may involve a degenerative process associated with aging; CPLA is also characterized by the loss of tone of the adjacent supporting connective tissue. Although the diagnosis is clinical, high-resolution Doppler ultrasound is a useful noninvasive tool for evaluating the lesion. This report describes the case of a 58-year-old male patient who complained of a lesion of the lower lip with bleeding and recurrent ulceration. The patient was successfully treated in our hospital after a diagnosis of CPLA and is currently undergoing a clinical outpatient follow-up with no complaints.

  6. Persistent Aerial Tracking

    KAUST Repository

    Mueller, Matthias

    2016-04-13

    In this thesis, we propose a new aerial video dataset and benchmark for low altitude UAV target tracking, as well as, a photo-realistic UAV simulator that can be coupled with tracking methods. Our benchmark provides the rst evaluation of many state of-the-art and popular trackers on 123 new and fully annotated HD video sequences captured from a low-altitude aerial perspective. Among the compared trackers, we determine which ones are the most suitable for UAV tracking both in terms of tracking accuracy and run-time. We also present a simulator that can be used to evaluate tracking algorithms in real-time scenarios before they are deployed on a UAV "in the field", as well as, generate synthetic but photo-realistic tracking datasets with free ground truth annotations to easily extend existing real-world datasets. Both the benchmark and simulator will be made publicly available to the vision community to further research in the area of object tracking from UAVs. Additionally, we propose a persistent, robust and autonomous object tracking system for unmanned aerial vehicles (UAVs) called Persistent Aerial Tracking (PAT). A computer vision and control strategy is applied to a diverse set of moving objects (e.g. humans, animals, cars, boats, etc.) integrating multiple UAVs with a stabilized RGB camera. A novel strategy is employed to successfully track objects over a long period, by \\'handing over the camera\\' from one UAV to another. We integrate the complete system into an off-the-shelf UAV, and obtain promising results showing the robustness of our solution in real-world aerial scenarios.

  7. Multiscale Persistent Functions for Biomolecular Structure Characterization

    Energy Technology Data Exchange (ETDEWEB)

    Xia, Kelin [Nanyang Technological University (Singapore). Division of Mathematical Sciences, School of Physical, Mathematical Sciences and School of Biological Sciences; Li, Zhiming [Central China Normal University, Wuhan (China). Key Laboratory of Quark and Lepton Physics (MOE) and Institute of Particle Physics; Mu, Lin [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Computer Science and Mathematics Division

    2017-11-02

    Here in this paper, we introduce multiscale persistent functions for biomolecular structure characterization. The essential idea is to combine our multiscale rigidity functions (MRFs) with persistent homology analysis, so as to construct a series of multiscale persistent functions, particularly multiscale persistent entropies, for structure characterization. To clarify the fundamental idea of our method, the multiscale persistent entropy (MPE) model is discussed in great detail. Mathematically, unlike the previous persistent entropy (Chintakunta et al. in Pattern Recognit 48(2):391–401, 2015; Merelli et al. in Entropy 17(10):6872–6892, 2015; Rucco et al. in: Proceedings of ECCS 2014, Springer, pp 117–128, 2016), a special resolution parameter is incorporated into our model. Various scales can be achieved by tuning its value. Physically, our MPE can be used in conformational entropy evaluation. More specifically, it is found that our method incorporates in it a natural classification scheme. This is achieved through a density filtration of an MRF built from angular distributions. To further validate our model, a systematical comparison with the traditional entropy evaluation model is done. Additionally, it is found that our model is able to preserve the intrinsic topological features of biomolecular data much better than traditional approaches, particularly for resolutions in the intermediate range. Moreover, by comparing with traditional entropies from various grid sizes, bond angle-based methods and a persistent homology-based support vector machine method (Cang et al. in Mol Based Math Biol 3:140–162, 2015), we find that our MPE method gives the best results in terms of average true positive rate in a classic protein structure classification test. More interestingly, all-alpha and all-beta protein classes can be clearly separated from each other with zero error only in our model. Finally, a special protein structure index (PSI) is proposed, for the first

  8. Fish population persistence in hydrologically variable landscapes.

    Science.gov (United States)

    Bond, Nick R; Balcombe, Stephen R; Crook, David A; Marshall, Jonathan C; Menke, Norbert; Lobegeiger, Jaye S

    2015-06-01

    Forecasting population persistence in environments subjected to periodic disturbances represents a general challenge for ecologists. In arid and semiarid regions, climate change and human water use pose significant threats to the future persistence of aquatic biota whose populations typically depend on permanent refuge waterholes for their viability. As such, habitats are increasingly being lost as a result of decreasing runoff and increasing water extraction. We constructed a spatially explicit population model for golden perch Macquaria ambigua (Richardson), a native freshwater fish in the Murray-Darling Basin in eastern Australia. We then used the model to examine the effects of increased aridity, increased drought frequency, and localized human water extraction on population viability. Consistent with current observations, the model predicted golden perch population persistence under the current climate and levels of water use. Modeled increases in local water extraction greatly increased the risk of population decline, while scenarios of increasing aridity and drought frequency were associated with only minor increases in this risk. We conclude that natural variability in abundances and high turnover rates (extinction/recolonization) of local populations dictate the importance of spatial connectivity and periodic cycles of population growth. Our study also demonstrates an effective way to examine population persistence in intermittent and ephemeral river systems by integrating spatial and temporal dynamics of waterhole persistence with demographic processes (survival, recruitment, and dispersal) within a stochastic modeling framework. The approach can be used to help understand the impacts of natural and anthropogenic drivers, including water resource development, on the viability of biota inhabiting highly dynamic environments.

  9. The origins of lactase persistence in Europe.

    Directory of Open Access Journals (Sweden)

    Yuval Itan

    2009-08-01

    Full Text Available Lactase persistence (LP is common among people of European ancestry, but with the exception of some African, Middle Eastern and southern Asian groups, is rare or absent elsewhere in the world. Lactase gene haplotype conservation around a polymorphism strongly associated with LP in Europeans (-13,910 C/T indicates that the derived allele is recent in origin and has been subject to strong positive selection. Furthermore, ancient DNA work has shown that the--13,910*T (derived allele was very rare or absent in early Neolithic central Europeans. It is unlikely that LP would provide a selective advantage without a supply of fresh milk, and this has lead to a gene-culture coevolutionary model where lactase persistence is only favoured in cultures practicing dairying, and dairying is more favoured in lactase persistent populations. We have developed a flexible demic computer simulation model to explore the spread of lactase persistence, dairying, other subsistence practices and unlinked genetic markers in Europe and western Asia's geographic space. Using data on--13,910*T allele frequency and farming arrival dates across Europe, and approximate Bayesian computation to estimate parameters of interest, we infer that the--13,910*T allele first underwent selection among dairying farmers around 7,500 years ago in a region between the central Balkans and central Europe, possibly in association with the dissemination of the Neolithic Linearbandkeramik culture over Central Europe. Furthermore, our results suggest that natural selection favouring a lactase persistence allele was not higher in northern latitudes through an increased requirement for dietary vitamin D. Our results provide a coherent and spatially explicit picture of the coevolution of lactase persistence and dairying in Europe.

  10. Persistent homology of complex networks

    International Nuclear Information System (INIS)

    Horak, Danijela; Maletić, Slobodan; Rajković, Milan

    2009-01-01

    Long-lived topological features are distinguished from short-lived ones (considered as topological noise) in simplicial complexes constructed from complex networks. A new topological invariant, persistent homology, is determined and presented as a parameterized version of a Betti number. Complex networks with distinct degree distributions exhibit distinct persistent topological features. Persistent topological attributes, shown to be related to the robust quality of networks, also reflect the deficiency in certain connectivity properties of networks. Random networks, networks with exponential connectivity distribution and scale-free networks were considered for homological persistency analysis

  11. Intrinsic and Inherited Inflation Persistence

    OpenAIRE

    Jeffrey C. Fuhrer

    2006-01-01

    In the now conventional view of the inflation process, the New Keynesian Phillips Curve (NKPC) captures most of the persistence in inflation. The sources of persistence are twofold. First, the “driving process” for inflation—the output gap or, more commonly, real marginal cost—is itself quite persistent, and a casual inspection of the NKPC reveals that inflation must “inherit” this persistence. Second, a modest amount of backward-looking or indexing behavior imparts some “intrinsic” persisten...

  12. A Triplet Repeat Expansion Genetic Mouse Model of Infantile Spasms Syndrome, Arx(GCG)10+7, with Interneuronopathy, Spasms in Infancy, Persistent Seizures, and Adult Cognitive and Behavioral Impairment

    Science.gov (United States)

    Price, Maureen G.; Yoo, Jong W.; Burgess, Daniel L.; Deng, Fang; Hrachovy, Richard A.; Frost, James D.; Noebels, Jeffrey L.

    2009-01-01

    Infantile spasms syndrome (ISS) is a catastrophic pediatric epilepsy with motor spasms, persistent seizures, mental retardation, and in some cases, autism. One of its monogenic causes is an insertion mutation (c.304ins (GCG)7) on the X chromosome, expanding the first polyalanine tract of the interneuron-specific transcription factor ARX from 16 to 23 alanine codons. Null mutation of the Arx gene impairs GABA- and cholinergic interneuronal migration but results in a neonatal lethal phenotype. We developed the first viable genetic mouse model of ISS that spontaneously recapitulates salient phenotypic features of the human triplet-repeat expansion mutation. Arx (GCG)10+7 (“Arx Plus7”) pups display abnormal spasm-like myoclonus and other key EEG features, including multifocal spikes, electrodecremental episodes, and spontaneous seizures persisting into maturity. The neurobehavioral profile of Arx mutants was remarkable for lowered anxiety, impaired associative learning, and abnormal social interaction. Laminar decreases of Arx+ cortical interneurons and a selective reduction of calbindin-, but not parvalbumin- or calretinin-expressing interneurons in neocortical layers and hippocampus indicate that specific classes of synaptic inhibition are missing from the adult forebrain, providing a basis for the seizures and cognitive disorder. A significant reduction of calbindin, NPY-expressing and cholinergic interneurons in the mutant striatum suggest that dysinhibition within this network may contribute to the dyskinetic motor spasms. This mouse model narrows the range of critical pathogenic elements within brain inhibitory networks essential to recreate this complex neurodevelopmental syndrome. PMID:19587282

  13. Persistent idiopathic facial pain.

    Science.gov (United States)

    Benoliel, Rafael; Gaul, Charly

    2017-06-01

    Background Persistent idiopathic facial pain (PIFP) is a chronic disorder recurring daily for more than two hours per day over more than three months, in the absence of clinical neurological deficit. PIFP is the current terminology for Atypical Facial Pain and is characterized by daily or near daily pain that is initially confined but may subsequently spread. Pain cannot be attributed to any pathological process, although traumatic neuropathic mechanisms are suspected. When present intraorally, PIFP has been termed 'Atypical Odontalgia', and this entity is discussed in a separate article in this special issue. PIFP is often a difficult but important differential diagnosis among chronic facial pain syndromes. Aim To summarize current knowledge on diagnostic criteria, differential diagnosis, pathophysiology and management of PIFP. Methods We present a narrative review reporting current literature and personal experience. Additionally, we discuss and differentiate the common differential diagnoses associated with PIFP including traumatic trigeminal neuropathies, regional myofascial pain, atypical neurovascular pains and atypical trigeminal neuropathic pains. Results and conclusion The underlying pathophysiology in PIFP is still enigmatic, however neuropathic mechanisms may be relevant. PIFP needs interdisciplinary collaboration to rule out and manage secondary causes, psychiatric comorbidities and other facial pain syndromes, particularly trigeminal neuralgia. Burden of disease and psychiatric comorbidity screening is recommended at an early stage of disease, and should be addressed in the management plan. Future research is needed to establish clear diagnostic criteria and treatment strategies based on clinical findings and individual pathophysiology.

  14. Blast exposure causes early and persistent aberrant phospho- and cleaved-tau expression in a murine model of mild blast-induced traumatic brain injury.

    Science.gov (United States)

    Huber, Bertrand R; Meabon, James S; Martin, Tobin J; Mourad, Pierre D; Bennett, Raymond; Kraemer, Brian C; Cernak, Ibolja; Petrie, Eric C; Emery, Michael J; Swenson, Erik R; Mayer, Cynthia; Mehic, Edin; Peskind, Elaine R; Cook, David G

    2013-01-01

    Mild traumatic brain injury (mTBI) is considered the 'signature injury' of combat veterans that have served during the wars in Iraq and Afghanistan. This prevalence of mTBI is due in part to the common exposure to high explosive blasts in combat zones. In addition to the threats of blunt impact trauma caused by flying objects and the head itself being propelled against objects, the primary blast overpressure (BOP) generated by high explosives is capable of injuring the brain. Compared to other means of causing TBI, the pathophysiology of mild-to-moderate BOP is less well understood. To study the consequences of BOP exposure in mice, we employed a well-established approach using a compressed gas-driven shock tube that recapitulates battlefield-relevant open-field BOP. We found that 24 hours post-blast a single mild BOP provoked elevation of multiple phospho- and cleaved-tau species in neurons, as well as elevating manganese superoxide-dismutase (MnSOD or SOD2) levels, a cellular response to oxidative stress. In hippocampus, aberrant tau species persisted for at least 30 days post-exposure, while SOD2 levels returned to sham control levels. These findings suggest that elevated phospho- and cleaved-tau species may be among the initiating pathologic processes induced by mild blast exposure. These findings may have important implications for efforts to prevent blast-induced insults to the brain from progressing into long-term neurodegenerative disease processes.

  15. Persistence of Rift Valley fever virus in East Africa

    Science.gov (United States)

    Gachohi, J.; Hansen, F.; Bett, B.; Kitala, P.

    2012-04-01

    Rift Valley fever virus (RVFv) is a mosquito-borne pathogen of livestock, wildlife and humans that causes severe outbreaks in intervals of several years. One of the open questions is how the virus persists between outbreaks. We developed a spatially-explicit, individual-based simulation model of the RVFv transmission dynamics to investigate this question. The model, is based on livestock and mosquito population dynamics. Spatial aspects are explicitly represented by a set of grid cells that represent mosquito breeding sites. A grid cell measures 500 by 500m and the model considers a grid of 100 by 100 grid cells; the model thus operates on the regional scale of 2500km2. Livestock herds move between grid cells, and provide connectivity between the cells. The model is used to explore the spatio-temporal dynamics of RVFv persistence in absence of a wildlife reservoir in an east African semi-arid context. Specifically, the model assesses the importance of local virus persistence in mosquito breeding sites relative to global virus persistence mitigated by movement of hosts. Local persistence is determined by the length of time the virus remains in a mosquito breeding site once introduced. In the model, this is a function of the number of mosquitoes that emerge infected and their lifespan. Global persistence is determined by the level of connectivity between isolated grid cells. Our work gives insights into the ecological and epidemiological conditions under which RVFv persists. The implication for disease surveillance and management are discussed.

  16. Procedures for estimation of genetic persistency indices for milk ...

    African Journals Online (AJOL)

    The Persistency Index will be released for sires with progeny following each national dairy genetic evaluation, allowing the South African dairy industry to select for changes in persistency in future. Keywords: Ayrshire, Guernsey, Holstein, Jersey, Repeatability model, test-day records. South African Journal of Animal ...

  17. Reconsidering the Relationship between Student Engagement and Persistence in College

    Science.gov (United States)

    Hu, Shouping

    2011-01-01

    Using data from two rounds of surveys on students in the Washington State Achievers (WSA) program, this study examined the relationship between student engagement in college activities and student persistence in college. Different approaches using student engagement measures in the persistence models were compared. The results indicated that the…

  18. Modelling of migration and fate of selected persistent organic pollutants in the Gulf of Gdansk and the Vistula catchment (Poland): selected results from the EU ELOISE EuroCat project

    Science.gov (United States)

    Zukowska, Barbara; Pacyna, Jozef; Namiesnik, Jacek

    2005-02-01

    The ELOISE EU EuroCat project integrated natural and social sciences to link the impacts affecting the coastal sea to the human activities developed along the catchments. In EuroCat project river catchments' changes and their impact on the inflow area were analysed. The information was linked with environmental models. The part of the EU ELOISE EuroCat project focusing on the Vistula River catchment and the Baltic Sea costal zone was named VisCat. Within the framework of the EU ELOISE EuroCat - VisCat project, CoZMo-POP (Coastal Zone Model for Persistent Organic Pollutants), a non-steady-state multicompartmental mass balance model of long-term chemical fate in the coastal environment or the drainage basin of a large lake environment was used. The model is parameterised and tested herein to simulate the long-term fate and distribution of selected HCHs (hexachlorocyclohexanes) and PCBs (polychlorinated biphenyls) in the Gulf of Gdansk and the Vistula River drainage basin environment. The model can also be used in the future to predict future concentrations in relation to various emission scenarios and in management of economic development and regulations of substance-emission to this environment. However, this would require more extensive efforts in the future on model parameterisation and validation in order to increase the confidence in current model outputs.

  19. Multidimensional persistence in biomolecular data.

    Science.gov (United States)

    Xia, Kelin; Wei, Guo-Wei

    2015-07-30

    Persistent homology has emerged as a popular technique for the topological simplification of big data, including biomolecular data. Multidimensional persistence bears considerable promise to bridge the gap between geometry and topology. However, its practical and robust construction has been a challenge. We introduce two families of multidimensional persistence, namely pseudomultidimensional persistence and multiscale multidimensional persistence. The former is generated via the repeated applications of persistent homology filtration to high-dimensional data, such as results from molecular dynamics or partial differential equations. The latter is constructed via isotropic and anisotropic scales that create new simiplicial complexes and associated topological spaces. The utility, robustness, and efficiency of the proposed topological methods are demonstrated via protein folding, protein flexibility analysis, the topological denoising of cryoelectron microscopy data, and the scale dependence of nanoparticles. Topological transition between partial folded and unfolded proteins has been observed in multidimensional persistence. The separation between noise topological signatures and molecular topological fingerprints is achieved by the Laplace-Beltrami flow. The multiscale multidimensional persistent homology reveals relative local features in Betti-0 invariants and the relatively global characteristics of Betti-1 and Betti-2 invariants. © 2015 Wiley Periodicals, Inc.

  20. Student Persistence in Community Colleges

    Science.gov (United States)

    Nakajima, Mikiko A.; Dembo, Myron H.; Mossler, Ron

    2012-01-01

    The current study extends the research on student persistence in community colleges by investigating factors likely to influence a student's decision to drop out or stay in school. Specifically, this study examined demographic, financial, academic, academic integration, and psychosocial variables and their relationship to student persistence. A…

  1. Molecular mechanisms underlying bacterial persisters

    DEFF Research Database (Denmark)

    Maisonneuve, Etienne; Gerdes, Kenn

    2014-01-01

    All bacteria form persisters, cells that are multidrug tolerant and therefore able to survive antibiotic treatment. Due to the low frequencies of persisters in growing bacterial cultures and the complex underlying molecular mechanisms, the phenomenon has been challenging to study. However, recent...

  2. Changes in antioxidant capacity of blood due to mutual action of electromagnetic field (1800 MHz) and opioid drug (tramadol) in animal model of persistent inflammatory state.

    Science.gov (United States)

    Bodera, Paweł; Stankiewicz, Wanda; Zawada, Katarzyna; Antkowiak, Bożena; Paluch, Małgorzata; Kieliszek, Jarosław; Kalicki, Bolesław; Bartosiński, Andrzej; Wawer, Iwona

    2013-01-01

    The biological effects and health implications of electromagnetic field (EMF) associated with cellular mobile telephones and related wireless systems and devices have become a focus of international scientific interest and world-wide public concern. It has also been proved that EMF influences the production of reactive oxygen species (ROS) in different tissues. Experiments were performed in healthy rats and in rats with persistent inflammatory state induced by Complete Freund's Adjuvant (CFA) injection, which was given 24 h before EMF exposure and drug application. Rats were injected with CFA or the same volume of paraffin oil into the plantar surface of the left hind paw. Animals were exposed to the far-field range of an antenna at 1800 MHz with the additional modulation which was identical to that generated by mobile phone GSM 1800. Rats were given 15 min exposure, or were sham-exposed with no voltage applied to the field generator in control groups. Immediately before EMF exposure, rats were injected intraperitoneally with tramadol in the 20 mg/kg dose or vehicle in the 1 ml/kg volume. Our study revealed that single EMF exposure in 1800 MHz frequency significantly reduced antioxidant capacity both in healthy animals and those with paw inflammation. A certain synergic mode of action between applied electromagnetic fields and administered tramadol in rats treated with CFA was observed. The aim of the study was to examine the possible, parallel/combined effects of electromagnetic radiation, artificially induced inflammation and a centrally-acting synthetic opioid analgesic drug, tramadol, (used in the treatment of severe pain) on the antioxidant capacity of blood of rats. The antioxidant capacity of blood of healthy rats was higher than that of rats which received only tramadol and were exposed to electromagnetic fields.

  3. Calculation of Persistent Currents in Superconducting Magnets

    CERN Document Server

    Völlinger, Christine; Russenschuck, Stephan

    2000-01-01

    The paper describes a semi-analytical hysteresis model for hard superconductors. The model is based on the critical state model considering the dependency of the critical current density on the varying local field in the superconducting filaments. By combining this hysteresis model with numerical field computation methods, it is possible to calculate the persistent current multipole errors in the magnet taking local saturation effects in the magnetic iron parts into consideration. As an application of the method, the use of soft magnetic iron sheets (coil protection sheets mounted between the coils and the collars) for the part compensation of the multipole errors during the ramping of the magnets is investigated.

  4. Heterologous Immunity and Persistent Murine Cytomegalovirus Infection.

    Science.gov (United States)

    Che, Jenny W; Daniels, Keith A; Selin, Liisa K; Welsh, Raymond M

    2017-01-15

    One's history of infections can affect the immune response to unrelated pathogens and influence disease outcome through the process of heterologous immunity. This can occur after acute viral infections, such as infections with lymphocytic choriomeningitis virus (LCMV) and vaccinia virus, where the pathogens are cleared, but it becomes a more complex issue in the context of persistent infections. In this study, murine cytomegalovirus (MCMV) was used as a persistent infection model to study heterologous immunity with LCMV. If mice were previously immune to LCMV and then infected with MCMV (LCMV+MCMV), they had more severe immunopathology, enhanced viral burden in multiple organs, and suppression of MCMV-specific T cell memory inflation. MCMV infection initially reduced the numbers of LCMV-specific memory T cells, but continued MCMV persistence did not further erode memory T cells specific to LCMV. When MCMV infection was given first (MCMV+LCMV), the magnitude of the acute T cell response to LCMV declined with age though this age-dependent decline was not dependent on MCMV. However, some of these MCMV persistently infected mice with acute LCMV infection (7 of 36) developed a robust immunodominant CD8 T cell response apparently cross-reactive between a newly defined putative MCMV epitope sequence, M57 727-734 , and the normally subdominant LCMV epitope L 2062-2069 , indicating a profound private specificity effect in heterologous immunity between these two viruses. These results further illustrate how a history of an acute or a persistent virus infection can substantially influence the immune responses and immune pathology associated with acute or persistent infections with an unrelated virus. This study extends our understanding of heterologous immunity in the context of persistent viral infection. The phenomenon has been studied mostly with viruses such as LCMV that are cleared, but the situation can be more complex with a persistent virus such as MCMV. We found that

  5. Meandering Rivers: How Important is Lateral Variability for Species Persistence?

    Science.gov (United States)

    Jin, Yu; Lutscher, Frithjof; Pei, Yuan

    2017-12-01

    Models for population dynamics in rivers and streams have highlighted the importance of spatial and temporal variations for population persistence. We present a novel model that considers the longitudinal variation as introduced by the sinuosity of a meandering river where a main channel is laterally extended to point bars in bends. These regions offer different habitat conditions for aquatic populations and therefore may enhance population persistence. Our model is a nonstandard reaction-advection-diffusion model where the domain of definition consists of the real line (representing the main channel) with periodically added intervals (representing the point bars). We give an existence and uniqueness proof for solutions of the equations. We then study population persistence as the (in-) stability of the trivial solution and population spread as the minimal wave speed of traveling periodic waves. We conduct a sensitivity analysis to highlight the importance of each parameter on the model outcome. We find that sinuosity can enhance species persistence.

  6. Persistence, resistance, resonance

    Science.gov (United States)

    Tsadka, Maayan

    form of musical consumption and experience. The three pieces draw lines connecting different aspects of persistence, resistance, and resonance.

  7. Extending and implementing the Persistent ID pillars

    Science.gov (United States)

    Car, Nicholas; Golodoniuc, Pavel; Klump, Jens

    2017-04-01

    The recent double decade anniversary of scholarly persistent identifier use has triggered journal special editions such as "20 Years of Persistent Identifiers". For such a publication, it is apt to consider the longevity of some persistent identifier (PID) mechanisms (Digital Object Identifiers) and the partial disappearance of others (Life Sciences IDs). We have previously postulated a set of "PID Pillars" [1] which are design principles aimed at ensuring PIDs can survive technology and social change and thus persist for the long term that we have drawn from our observations of PIDs at work over many years. The principles: describe how to ensure identifiers' system and organisation independence; codify the delivery of essential PID system functions; mandate a separation of PID functions from data delivery mechanisms; and require generation of policies detailing how change is handled. In this presentation, first we extend on our previous work of introducing the pillars by refining their descriptions, giving specific suggestions for each and presenting some work that addresses them. Second, we propose a baseline data model for persistent identifiers that, if used, would assist the separation of PID metadata and PID system functioning. This would allow PID system function specifics to change over time (e.g. resolver services or even resolution protocols) and yet preserve the PIDs themselves. Third, we detail our existing PID system — the PID Service [2] — that partially implements the pillars and describe both its successes and shortcomings. Finally, we describe our planned next-generation system that will aim to use the baseline data model and fully implement the pillars.

  8. Energy landscapes and persistent minima

    Energy Technology Data Exchange (ETDEWEB)

    Carr, Joanne M.; Wales, David J., E-mail: dw34@cam.ac.uk [University Chemical Laboratories, University of Cambridge, Lensfield Road, Cambridge CB2 1EW (United Kingdom); Mazauric, Dorian; Cazals, Frédéric, E-mail: frederic.cazals@inria.fr [Inria Sophia Antipolis Méditerranée, 2004 route des Lucioles, F-06902 Sophia Antipolis (France)

    2016-02-07

    We consider a coarse-graining of high-dimensional potential energy landscapes based upon persistences, which correspond to lowest barrier heights to lower-energy minima. Persistences can be calculated efficiently for local minima in kinetic transition networks that are based on stationary points of the prevailing energy landscape. The networks studied here represent peptides, proteins, nucleic acids, an atomic cluster, and a glassy system. Minima with high persistence values are likely to represent some form of alternative structural morphology, which, if appreciably populated at the prevailing temperature, could compete with the global minimum (defined as infinitely persistent). Threshold values on persistences (and in some cases equilibrium occupation probabilities) have therefore been used in this work to select subsets of minima, which were then analysed to see how well they can represent features of the full network. Simplified disconnectivity graphs showing only the selected minima can convey the funnelling (including any multiple-funnel) characteristics of the corresponding full graphs. The effect of the choice of persistence threshold on the reduced disconnectivity graphs was considered for a system with a hierarchical, glassy landscape. Sets of persistent minima were also found to be useful in comparing networks for the same system sampled under different conditions, using minimum oriented spanning forests.

  9. The Enigmatic Persistence of Anorexia Nervosa

    Science.gov (United States)

    Walsh, B. Timothy

    2014-01-01

    Objective In this review, based on recent advances in cognitive neuroscience, the author presents a formulation in which the marked persistence of anorexia nervosa can be usefully understood as a well-ingrained maladaptive habit. Method The author reviewed the relevant literature on the development and course of anorexia nervosa and interpreted critical features in light of developments in cognitive neuroscience. Results Anorexia nervosa is a well characterized disorder with remarkable persistence both across history and among affected individuals. Food restriction, the salient behavioral feature of the disorder, often begins innocently but gradually takes on a life of its own. Over time, it becomes highly entrenched and resistant to change through either psychological or pharmacological treatment. Cognitive neuroscience has described two related but distinct processes that underlie the acquisition of new patterns of behavior, namely, action-outcome and stimulus-response learning. It is likely that both processes are engaged in the development of anorexia nervosa and that stimulus-response learning (that is, habit formation) is critical to the persistence of the dieting behavior. Conclusions The formulation of the dieting behavior characteristic of anorexia nervosa as a well-entrenched habit provides a basis for understanding the striking persistence of this disorder. This model helps explain the resistance of anorexia nervosa to interventions that have established efficacy in related disorders and implies that addressing the dieting behavior is critical, especially early in the course of the illness, before it has become ingrained. PMID:23429750

  10. Proposición de un modelo matemático simple de persistencia de herbicidas en el suelo Simple mathematical model proposition of herbicide persistence in the soil

    Directory of Open Access Journals (Sweden)

    RICARDO FUENTES

    2000-12-01

    Full Text Available El estudio propone un modelo simple de persistencia de herbicidas en el suelo basado en una serie de modificaciones al modelo desarrollado por Walker & Barnes. El modelo que se propone simula la degradación diaria de un herbicida en el suelo, a través del funcionamiento de tres submodelos: a submodelo que estima la temperatura del suelo, b submodelo del cálculo del contenido de humedad del suelo y c submodelo que calcula la degradación del producto. Se entrega una descripción teórica de las modificaciones introducidas al modelo y un detalle del programa computacional en lenguaje BASIC. Se hizo una validación independiente de cada uno de los submodelos modificados y se concluye que todos ellos mejoran su eficiencia de predicción respecto al modelo original. La validación del submodelo de degradación se realizó utilizando información obtenida en campo en dos suelos diferentes de los herbicidas metsulfuron-metil y triasulfuron. Finalmente se concluye que el modelo propuesto sería eficiente en la simulación de la persistencia de estas sulfonilureas en el suelo, utilizando una cinética de primer grado para metsulfuron-metil y una de segundo grado para triasulfuron.The present study proposes a simple model of persistence of herbicides in soil based on a series of modifications to the model developed by Walker & Barnes. The model proposed simulates the daily degradation of a herbicide in soil, through three submodels: a soil temperature submodel, b soil moisture content submodel and, c degradation of the product submodel. A theoretical description of the modifications introduced to the model and a detail of the software program in language BASIC are given. An independent validation of each one of the modified submodels was done and it concludes that all of them improve the efficiency of prediction of the original model. The validation of the degradation submodel was made using field obtained information in two different soils from the

  11. Emotional persistence in online chatting communities

    Science.gov (United States)

    Garas, Antonios; Garcia, David; Skowron, Marcin; Schweitzer, Frank

    2012-05-01

    How do users behave in online chatrooms, where they instantaneously read and write posts? We analyzed about 2.5 million posts covering various topics in Internet relay channels, and found that user activity patterns follow known power-law and stretched exponential distributions, indicating that online chat activity is not different from other forms of communication. Analysing the emotional expressions (positive, negative, neutral) of users, we revealed a remarkable persistence both for individual users and channels. I.e. despite their anonymity, users tend to follow social norms in repeated interactions in online chats, which results in a specific emotional ``tone'' of the channels. We provide an agent-based model of emotional interaction, which recovers qualitatively both the activity patterns in chatrooms and the emotional persistence of users and channels. While our assumptions about agent's emotional expressions are rooted in psychology, the model allows to test different hypothesis regarding their emotional impact in online communication.

  12. Persistent photoconductivity in strontium titanate.

    Science.gov (United States)

    Tarun, Marianne C; Selim, Farida A; McCluskey, Matthew D

    2013-11-01

    Persistent photoconductivity was observed in strontium titanate (SrTiO(3)) single crystals. When exposed to sub-bandgap light (2.9 eV or higher) at room temperature, the free-electron concentration increases by over 2 orders of magnitude. After the light is turned off, the enhanced conductivity persists for several days, with negligible decay. From positron lifetime measurements, the persistent photoconductivity is attributed to the excitation of an electron from a titanium vacancy defect into the conduction band, with a very low recapture rate.

  13. Speciation and Persistence of Dimethoate in the Aquatic Environment

    African Journals Online (AJOL)

    Speciation and Persistence of Dimethoate in the Aquatic Environment: Characterization in Terms of a Rate Model that Takes Into Account Hydrolysis, Photolysis, Microbial Degradation and Adsorption of the Pesticide by Colloidal and Sediment Particles.

  14. Testing hypotheses in an I(2) model with piecewise linear trends. An analysis of the persistent long swings in the Dmk/$ rate

    DEFF Research Database (Denmark)

    Johansen, Søren; Juselius, Katarina; Frydman, Roman

    2010-01-01

    This paper discusses the I(2) model with breaks in the deterministic component and illustrates with an analysis of German and US prices, exchange rates, and interest rates in 1975--1999. It provides new results on the likelihood ratio test of overidentifying restrictions on the cointegrating rela...

  15. Changes in action potentials and intracellular ionic homeostasis in a ventricular cell model related to a persistent sodium current in SCN5A mutations underlying LQT3

    Czech Academy of Sciences Publication Activity Database

    Christé, G.; Chahine, M.; Chevalier, P.; Pásek, Michal

    2008-01-01

    Roč. 96, - (2008), s. 281-293 ISSN 0079-6107 Institutional research plan: CEZ:AV0Z20760514 Keywords : cardiac cell * SCN5A mutation * Long QT syndrome * quantitative modelling Subject RIV: BO - Biophysics Impact factor: 6.388, year: 2008

  16. Persistent Effects of Acute Stress on Fear and Drug-Seeking in a Novel Model of the Comorbidity between Post-Traumatic Stress Disorder and Addiction

    Science.gov (United States)

    Pizzimenti, Christie L.; Navis, Tom M.; Lattal, K. Matthew

    2017-01-01

    Even following long periods of abstinence, individuals with anxiety disorders have high rates of relapse to drugs of abuse. Although many current models of relapse demonstrate effects of acute stress on drug-seeking, most of these studies examine stressful experiences that occur in close temporal and physical proximity to the reinstatement test.…

  17. Exploring the persistence of stream-dwelling trout populations under alternative real-world turbidity regimes with an individual-based model

    Science.gov (United States)

    Bret C. Harvey; Steven F. Railsback

    2009-01-01

    We explored the effects of elevated turbidity on stream-resident populations of coastal cutthroat trout Oncorhynchus clarkii clarkii using a spatially explicit individual-based model. Turbidity regimes were contrasted by means of 15-year simulations in a third-order stream in northwestern California. The alternative regimes were based on multiple-year, continuous...

  18. Persistent arm pain is distinct from persistent breast pain following breast cancer surgery.

    Science.gov (United States)

    Langford, Dale J; Paul, Steven M; West, Claudia; Abrams, Gary; Elboim, Charles; Levine, Jon D; Hamolsky, Deborah; Luce, Judith A; Kober, Kord M; Neuhaus, John M; Cooper, Bruce A; Aouizerat, Bradley E; Miaskowski, Christine

    2014-12-01

    Persistent pain following breast cancer surgery is well documented. However, it is not well characterized in terms of the anatomic site affected (ie, breast, arm). In 2 separate growth mixture modeling analyses, we identified subgroups of women (N = 398) with distinct breast pain and arm pain trajectories. The fact that these latent classes differed by anatomic site, types of tissue affected, and neural innervation patterns suggests the need for separate evaluations of these distinct persistent pain conditions. The purposes of this companion study were to identify demographic and clinical characteristics that differed between the 2 arm pain classes and determine if differences existed over time in sensitivity in the upper inner arm and axillary lymph node dissection sites, pain qualities, pain interference, and hand and arm function, as well as to compare findings with persistent breast pain. Higher occurrence rates for depression and lymphedema were found in the moderate arm pain class. Regardless of pain group membership, sensory loss was observed in the upper inner arm and axillary lymph node dissection site. Arm pain was described similarly to neuropathic pain and interfered with daily functioning. Persistent arm pain was associated with sustained impairments in shoulder mobility. For persistent breast and arm pain, changes in sensation following breast cancer surgery were notable. Persistent arm pain was associated with sustained interference with daily functioning and upper body mobility impairments. Long-term management of persistent pain following breast cancer surgery is warranted to improve the quality of survivorship for these women. Copyright © 2014 American Pain Society. Published by Elsevier Inc. All rights reserved.

  19. Saikosaponin a mediates the anticonvulsant properties in the HNC models of AE and SE by inhibiting NMDA receptor current and persistent sodium current.

    Directory of Open Access Journals (Sweden)

    Yun-Hong Yu

    Full Text Available Epilepsy is one of the most common neurological disorders, yet its treatment remains unsatisfactory. Saikosaponin a (SSa, a triterpene saponin derived from Bupleurum chinensis DC., has been demonstrated to have significant antiepileptic activity in a variety of epilepsy models in vivo. However, the electrophysiological activities and mechanisms of the antiepileptic properties of SSa remain unclear. In this study, whole-cell current-clamp recordings were used to evaluate the anticonvulsant activities of SSa in the hippocampal neuronal culture (HNC models of acquired epilepsy (AE and status epilepticus (SE. Whole-cell voltage-clamp recordings were used to evaluate the modulation effects of SSa on NMDA-evoked current and sodium currents in cultured hippocampal neurons. We found that SSa effectively terminated spontaneous recurrent epileptiform discharges (SREDs in the HNC model of AE and continuous epileptiform high-frequency bursts (SE in the HNC model of SE, in a concentration-dependent manner with an IC(50 of 0.42 µM and 0.62 µM, respectively. Furthermore, SSa significantly reduced the peak amplitude of NMDA-evoked current and the peak current amplitude of I(NaP. These results suggest for the first time that the inhibitions of NMDA receptor current and I(NaP may be the underlying mechanisms of SSa's anticonvulsant properties, including the suppression of SREDs and SE in the HNC models of AE and SE. In addition, effectively abolishing the refractory SE implies that SSa may be a potential anticonvulsant candidate for the clinical treatment of epilepsy.

  20. Pricing Volatility of Stock Returns with Volatile and Persistent Components

    DEFF Research Database (Denmark)

    Zhu, Jie

    2009-01-01

    This paper introduces a two-component volatility model based on first moments of both components to describe the dynamics of speculative return volatility. The two components capture the volatile and the persistent part of volatility, respectively. The model is applied to 10 Asia-Pacific stock ma...... markets. A positive or risk-premium effect exists between the return and the volatile component, yet the persistent component is not significantly priced for the return dynamic process....

  1. Teriparatide Induced Delayed Persistent Hypercalcemia

    OpenAIRE

    Thiruchelvam, Nirosshan; Randhawa, Jaskirat; Sadiek, Happy; Kistangari, Gaurav

    2014-01-01

    Teriparatide, a recombinant PTH, is an anabolic treatment for osteoporosis that increases bone density. Transient hypercalcemia is a reported side effect of teriparatide that is seen few hours following administration of teriparatide and resolves usually within 16 hours of drug administration. Persistent hypercalcemia, although not observed in clinical trials, is rarely reported. The current case describes a rare complication of teriparatide induced delayed persistent hypercalcemia.

  2. Teriparatide Induced Delayed Persistent Hypercalcemia

    Directory of Open Access Journals (Sweden)

    Nirosshan Thiruchelvam

    2014-01-01

    Full Text Available Teriparatide, a recombinant PTH, is an anabolic treatment for osteoporosis that increases bone density. Transient hypercalcemia is a reported side effect of teriparatide that is seen few hours following administration of teriparatide and resolves usually within 16 hours of drug administration. Persistent hypercalcemia, although not observed in clinical trials, is rarely reported. The current case describes a rare complication of teriparatide induced delayed persistent hypercalcemia.

  3. Persistent Identifiers for Dutch cultural heritage institutions

    Science.gov (United States)

    Ras, Marcel; Kruithof, Gijsbert

    2016-04-01

    Over the past years, more and more collections belonging to archives, libraries, media, museums, and knowledge institutes are being digitised and made available online. These are exciting times for ALM institutions. They are realising that, in the information society, their collections are goldmines. Unfortunately most heritage institutions in the Netherlands do not yet meet the basic preconditions for long-term availability of their collections. The digital objects often have no long lasting fixed reference yet. URL's and web addresses change. Some digital objects that were referenced in Europeana and other portals can no longer be found. References in scientific articles have a very short life span, which is damaging for scholarly research. In 2015, the Dutch Digital Heritage Network (NDE) has started a two-year work program to co-ordinate existing initiatives in order to improve the (long-term) accessibility of the Dutch digital heritage for a wide range of users, anytime, anyplace. The Digital Heritage Network is a partnership established on the initiative of the Ministry of Education, Culture and Science. The members of the NDE are large, national institutions that strive to professionally preserve and manage digital data, e.g. the National Library, The Netherlands Institute for Sound and Vision, the Netherlands Cultural Heritage Agency, the Royal Netherlands Academy of Arts and Sciences, the National Archive of the Netherlands and the DEN Foundation, and a growing number of associations and individuals both within and outside the heritage sector. By means of three work programmes the goals of the Network should be accomplished and improve the visibility, the usability and the sustainability of digital heritage. Each programme contains of a set of projects. Within the sustainability program a project on creating a model for persistent identifiers is taking place. The main goals of the project are (1) raise awareness among cultural heritage institutions on the

  4. Persistence of undergraduate women in STEM fields

    Science.gov (United States)

    Pedone, Maggie Helene

    The underrepresentation of women in science, technology, engineering, and mathematics (STEM) is a complex problem that continues to persist at the postsecondary level, particularly in computer science and engineering fields. This dissertation explored the pre-college and college level factors that influenced undergraduate women's persistence in STEM. This study also examined and compared the characteristics of undergraduate women who entered STEM fields and non-STEM fields in 2003-2004. The nationally representative Beginning Postsecondary Students Longitudinal Study (BPS:04/09) data set was used for analysis. BPS:04/09 study respondents were surveyed three times (NPSAS:04, BPS:04/06, BPS:04/09) over a six-year period, which enabled me to explore factors related to long-term persistence. Astin's Input-Environment-Output (I-E-O) model was used as the framework to examine student inputs and college environmental factors that predict female student persistence (output) in STEM. Chi-square tests revealed significant differences between undergraduate women who entered STEM and non-STEM fields in 2003-2004. Differences in student demographics, prior academic achievement, high school course-taking patterns, and student involvement in college such as participation in study groups and school clubs were found. Notably, inferential statistics showed that a significantly higher proportion of female minority students entered STEM fields than non-STEM fields. These findings challenge the myth that underrepresented female minorities are less inclined to enter STEM fields. Logistic regression analyses revealed thirteen significant predictors of persistence for undergraduate women in STEM. Findings showed that undergraduate women who were younger, more academically prepared, and academically and socially involved in college (e.g., lived on campus, interacted with faculty, participated in study groups, fine arts activities, and school sports) were more likely to persist in STEM

  5. Persistent gating deficit and increased sensitivity to NMDA receptor antagonism after puberty in a new mouse model of the human 22q11.2 microdeletion syndrome

    DEFF Research Database (Denmark)

    Didriksen, Michael; Fejgin, Kim; Nilsson, Simon R O

    2016-01-01

    in a wide range of other behavioural and biochemical assays. LIMITATIONS: The 22q11.2 microdeletion has incomplete penetrance in humans, and the severity of disease depends on the complete genetic makeup in concert with environmental factors. In order to obtain more marked phenotypes reflecting the severe...... conditions related to 22q11.2DS it is suggested to expose the Df(h22q11)/+ mice to environmental stressors that may unmask latent psychopathology. CONCLUSION: The Df(h22q11)/+ model will be a valuable tool for increasing our understanding of the etiology of schizophrenia and other psychiatric disorders......BACKGROUND: The hemizygous 22q11.2 microdeletion is a common copy number variant in humans. The deletion confers high risk for neurodevelopmental disorders, including autism and schizophrenia. Up to 41% of deletion carriers experience psychotic symptoms. METHODS: We present a new mouse model (Df...

  6. Persistent gating deficit and increased sensitivity to NMDA receptor antagonism after puberty in a new mouse model of the human 22q11.2 microdeletion syndrome

    DEFF Research Database (Denmark)

    Didriksen, Michael; Fejgin, Kim; Nilsson, Simon R O

    2017-01-01

    in a wide range of other behavioural and biochemical assays. Limitations: The 22q11.2 microdeletion has incomplete penetrance in humans, and the severity of disease depends on the complete genetic makeup in concert with environmental factors. In order to obtain more marked phenotypes reflecting the severe...... conditions related to 22q11.2DS it is suggested to expose the Df(h22q11)/+ mice to environmental stressors that may unmask latent psychopathology. Conclusion: The Df(h22q11)/+ model will be a valuable tool for increasing our understanding of the etiology of schizophrenia and other psychiatric disorders......Background: The hemizygous 22q11.2 microdeletion is a common copy number variant in humans. The deletion confers high risk for neurodevelopmental disorders, including autism and schizophrenia. Up to 41% of deletion carriers experience psychotic symptoms. Methods: We present a new mouse model (Df...

  7. A Probabilistic Model in Cross-Sectional Studies for Identifying Interactions between Two Persistent Vector-Borne Pathogens in Reservoir Populations

    OpenAIRE

    Vaumourin, Elise; Gasqui, Patrick; Buffet, Jean-Philippe; Chapuis, Jean-Louis; Pisanu, Benoit; Ferquel, Elisabeth; Vayssier-Taussat, Muriel; Vourc'h, Gwenael

    2013-01-01

    International audience; BACKGROUND: In natural populations, individuals are infected more often by several pathogens than by just one. In such a context, pathogens can interact. This interaction could modify the probability of infection by subsequent pathogens. Identifying when pathogen associations correspond to biological interactions is a challenge in cross-sectional studies where the sequence of infection cannot be demonstrated. METHODOLOGY/PRINCIPAL FINDINGS: Here we modelled the probabi...

  8. Statistical Inference for Porous Materials using Persistent Homology.

    Energy Technology Data Exchange (ETDEWEB)

    Moon, Chul [Univ. of Georgia, Athens, GA (United States); Heath, Jason E. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Mitchell, Scott A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2017-12-01

    We propose a porous materials analysis pipeline using persistent homology. We rst compute persistent homology of binarized 3D images of sampled material subvolumes. For each image we compute sets of homology intervals, which are represented as summary graphics called persistence diagrams. We convert persistence diagrams into image vectors in order to analyze the similarity of the homology of the material images using the mature tools for image analysis. Each image is treated as a vector and we compute its principal components to extract features. We t a statistical model using the loadings of principal components to estimate material porosity, permeability, anisotropy, and tortuosity. We also propose an adaptive version of the structural similarity index (SSIM), a similarity metric for images, as a measure to determine the statistical representative elementary volumes (sREV) for persistence homology. Thus we provide a capability for making a statistical inference of the uid ow and transport properties of porous materials based on their geometry and connectivity.

  9. A Clinical Drug Library Screen Identifies Tosufloxacin as Being Highly Active against Staphylococcus aureus Persisters

    Directory of Open Access Journals (Sweden)

    Hongxia Niu

    2015-07-01

    Full Text Available To identify effective compounds that are active against Staphylococcus aureus (S. aureus persisters, we screened a clinical drug library consisting of 1524 compounds and identified six drug candidates that had anti-persister activity: tosufloxacin, clinafloxacin, sarafloxacin, doxycycline, thiostrepton, and chlorosalicylanilide. Among them, tosufloxacin had the highest anti-persister activity, which could completely eradicate S. aureus persisters within 2 days in vitro. Clinafloxacin ranked the second with very few persisters surviving the drug exposure. Interestingly, we found that both tosufloxacin and trovafloxacin that had high activity against persisters contained at the N-1 position the 2,4-difluorophenyl group, which is absent in other less active quinolones and may be associated with the high anti-persister activity. Further studies are needed to evaluate tosufloxacin in animal models and to explain its unique activity against bacterial persisters. Our findings may have implications for improved treatment of persistent bacterial infections.

  10. Urotensin-II contributes to pulmonary vasoconstriction in a perinatal model of persistent pulmonary hypertension of the newborn secondary to meconium aspiration syndrome.

    Science.gov (United States)

    Simpson, Catherine M; Smolich, Joseph J; Shekerdemian, Lara S; Penny, Daniel J

    2010-02-01

    Meconium aspiration syndrome (MAS) disrupts perinatal decreases in pulmonary vascular resistance (PVR) and is the commonest cause of neonatal pulmonary hypertension. The contribution of the potent vasoactive agent urotensin-II (U-II), in the pathophysiology of this condition, is unknown. In a new perinatal model of MAS, we combined measurement of circulating U-II levels with U-II receptor blockade studies. Nineteen anesthetized lambs were instrumented then randomly allocated to the following groups: 1) control (n = 5), 2) control plus specific U-II receptor blockade with palosuran (n = 5), 3) tracheal instillation of meconium (n = 5), 4) meconium instillation plus palosuran (n = 4). Hemodynamics, PVR, and plasma U-II were measured for 6 h after delivery. After birth in controls, U-II increased (p meconium lambs displayed a greater rise in U-II levels (p < 0.05 versus control) with an increase in PVR (p < 0.005) that was attenuated by U-II receptor blockade (p < 0.001). These findings suggest that U-II normally acts as a pulmonary vasodilator after birth, but in the presence of MAS, it assumes a vasoconstrictor role. U-II receptor blockade also improves pulmonary hemodynamics in this model.

  11. Characterization and transcriptome analysis of Mycobacterium tuberculosis persisters.

    Science.gov (United States)

    Keren, Iris; Minami, Shoko; Rubin, Eric; Lewis, Kim

    2011-01-01

    Tuberculosis continues to be a major public health problem in many parts of the world. Significant obstacles in controlling the epidemic are the length of treatment and the large reservoir of latently infected people. Bacteria form dormant, drug-tolerant persister cells, which may be responsible for the difficulty in treating both acute and latent infections. We find that in Mycobacterium tuberculosis, low numbers of drug-tolerant persisters are present in lag and early exponential phases, increasing sharply at late exponential and stationary phases to make up ~1% of the population. This suggests that persister formation is governed by both stochastic and deterministic mechanisms. In order to isolate persisters, an exponentially growing population was treated with d-cycloserine, and cells surviving lysis were collected by centrifugation. A transcriptome of persisters was obtained by using hybridization to an Affymetrix array. The transcriptome shows downregulation of metabolic and biosynthetic pathways, consistent with a certain degree of dormancy. A set of genes was upregulated in persisters, and these are likely involved in persister formation and maintenance. A comparison of the persister transcriptome with transcriptomes obtained for several in vitro dormancy models identified a small number of genes upregulated in all cases, which may represent a core dormancy response. © 2011 Keren et al.

  12. The role of viral persistence in flavivirus biology

    Science.gov (United States)

    Mlera, Luwanika; Melik, Wessam; Bloom, Marshall E.

    2014-01-01

    In nature, vector-borne flaviviruses are persistently cycled between either the tick or mosquito vector and small mammals such as rodents, skunks, and swine. These viruses account for considerable human morbidity and mortality worldwide. Increasing and substantial evidence of viral persistence in humans, which includes the isolation of RNA by RT-PCR and infectious virus by culture, continues to be reported. Viral persistence can also be established in vitro in various human, animal, arachnid and insect cell lines in culture. Although some research has focused on the potential roles of defective virus particles, evasion of the immune response through the manipulation of autophagy and/or apoptosis, the precise mechanism of flavivirus persistence is still not well understood. We propose additional research for further understanding of how viral persistence is established in different systems. Avenues for additional studies include determining if the multifunctional flavivirus protein NS5 has a role in viral persistence, the development of relevant animal models of viral persistence as well as investigating the host responses that allow vector borne flavivirus replication without detrimental effects on infected cells. Such studies might shed more light on the viral-host relationships, and could be used to unravel the mechanisms for establishment of persistence. PMID:24737600

  13. Spatial patterns of drought persistence in East China

    Science.gov (United States)

    Meng, L.; Ford, T.

    2017-12-01

    East China has experienced a number of severe droughts in recent decades. Understanding the characteristics of droughts and their persistence will provide operational guidelines for water resource management and agricultural production. This study uses a logistic regression model to measure the probability of drought occurrence in the current season given the previous season's Standardized Precipitation Index (SPI) and Southern Oscillation Index (SOI) as well as drought persistence. Results reveal large spatial and seasonal variations in the relationship between the previous season's SPI and the drought occurrence probability in a given season. The drought persistence averaged over the entire study area for all the four seasons is approximately 34% with large variations from season to season and from region to region. The East and Northeast regions have the largest summer drought persistence ( 40%) and lowest fall drought persistence ( 28%). The spatial pattern in winter and spring drought persistence is dissimilar with stronger winter and weaker spring drought persistence in the Southwest and Northeast relative to other regions. Logistic regression analysis indicates a stronger negative relationship in summer-to-fall (or between fall drought occurrence and summer SPI) than other inter-season relationships. This study demonstrates that the impact of previous season SPI and SOI on current season drought varies substantially from region to region and from season to season. This study also shows stronger drought persistence in summer than in other seasons. In other words, the probability of fall drought occurrence is closely related to summer moisture conditions in the East China.

  14. Variable Persister Gene Interactions with (pppGpp for Persister Formation in Escherichia coli

    Directory of Open Access Journals (Sweden)

    Shuang Liu

    2017-09-01

    Full Text Available Persisters comprise a group of phenotypically heterogeneous metabolically quiescent bacteria with multidrug tolerance and contribute to the recalcitrance of chronic infections. Although recent work has shown that toxin-antitoxin (TA system HipAB depends on stringent response effector (pppGppin persister formation, whether other persister pathways are also dependent on stringent response has not been explored. Here we examined the relationship of (pppGpp with 15 common persister genes (dnaK, clpB, rpoS, pspF, tnaA, sucB, ssrA, smpB, recA, umuD, uvrA, hipA, mqsR, relE, dinJ using Escherichia coli as a model. By comparing the persister levels of wild type with their single gene knockout and double knockout mutants with relA, we divided their interactions into five types, namely A “dependent” (dnaK, recA, B “positive reinforcement” (rpoS, pspF, ssrA, recA, C “antagonistic” (clpB, sucB, umuD, uvrA, hipA, mqsR, relE, dinJ, D “epistasis” (clpB, rpoS, tnaA, ssrA, smpB, hipA, and E “irrelevant” (dnaK, clpB, rpoS, tnaA, sucB, smpB, umuD, uvrA, hipA, mqsR, relE, dinJ. We found that the persister gene interactions are intimately dependent on bacterial culture age, cell concentrations (diluted versus undiluted culture, and drug classifications, where the same gene may belong to different groups with varying antibiotics, culture age or cell concentrations. Together, this study represents the first attempt to systematically characterize the intricate relationships among the different mechanisms of persistence and as such provide new insights into the complexity of the persistence phenomenon at the level of persister gene network interactions.

  15. Heterosexual Male Carriers Could Explain Persistence of Homosexuality in Men: Individual-Based Simulations of an X-Linked Inheritance Model.

    Science.gov (United States)

    Chaladze, Giorgi

    2016-10-01

    Homosexuality has been documented throughout history and is found in almost all human cultures. Twin studies suggest that homosexuality is to some extent heritable. However, from an evolutionary perspective, this poses a problem: Male homosexuals tend to have on average five times fewer children than heterosexual males, so how can a phenomenon associated with low reproductive success be maintained at relatively stable frequencies? Recent findings of increased maternal fecundity of male homosexuals suggest that the genes responsible for homosexuality in males increase fecundity in the females who carry them. Can an increase in maternal fecundity compensate for the fecundity reduction in homosexual men and produce a stable polymorphism? In the current study, this problem was addressed with an individual-based modeling (IBM) approach. IBM suggests that male homosexuality can be maintained in a population at low and stable frequencies if roughly more than half of the females and half of the males are carriers of genes that predispose the male to homosexuality.

  16. Persistent draining crossover in DNA and other semi-flexible polymers: Evidence from hydrodynamic models and extensive measurements on DNA solutions

    Science.gov (United States)

    Mansfield, Marc L.; Tsortos, Achilleas; Douglas, Jack F.

    2015-09-01

    Although the scaling theory of polymer solutions has had many successes, this type of argument is deficient when applied to hydrodynamic solution properties. Since the foundation of polymer science, it has been appreciated that measurements of polymer size from diffusivity, sedimentation, and solution viscosity reflect a convolution of effects relating to polymer geometry and the strength of the hydrodynamic interactions within the polymer coil, i.e., "draining." Specifically, when polymers are expanded either by self-excluded volume interactions or inherent chain stiffness, the hydrodynamic interactions within the coil become weaker. This means there is no general relationship between static and hydrodynamic size measurements, e.g., the radius of gyration and the hydrodynamic radius. We study this problem by examining the hydrodynamic properties of duplex DNA in solution over a wide range of molecular masses both by hydrodynamic modeling using a numerical path-integration method and by comparing with extensive experimental observations. We also considered how excluded volume interactions influence the solution properties of DNA and confirm that excluded volume interactions are rather weak in duplex DNA in solution so that the simple worm-like chain model without excluded volume gives a good leading-order description of DNA for molar masses up to 107 or 108 g/mol or contour lengths between 5 μm and 50 μm. Since draining must also depend on the detailed chain monomer structure, future work aiming to characterize polymers in solution through hydrodynamic measurements will have to more carefully consider the relation between chain molecular structure and hydrodynamic solution properties. In particular, scaling theory is inadequate for quantitative polymer characterization.

  17. Monitoring Coastal Marshes for Persistent Saltwater Intrusion

    Science.gov (United States)

    Kalcic, Maria; Hall, Callie; Fletcher, Rose; Russell, Jeff

    2009-01-01

    Primary goal: Provide resource managers with remote sensing products that support ecosystem forecasting models requiring salinity and inundation data. Work supports the habitat-switching modules in the Coastal Louisiana Ecosystem Assessment and Restoration (CLEAR) model, which provides scientific evaluation for restoration management (Visser et al., 2008). Ongoing work to validate flooding with radar (NWRC/USGS) and enhance persistence estimates through "fusion" of MODIS and Landsat time series (ROSES A.28 Gulf of Mexico). Additional work will also investigate relationship between saltwater dielectric constant and radar returns (Radarsat) (ROSES A.28 Gulf of Mexico).

  18. Progression and recovery of Parkinsonism in a chronic progressive MPTP-induction model in the marmoset without persistent molecular and cellular damage.

    Science.gov (United States)

    Franke, S K; van Kesteren, R E; Wubben, J A M; Hofman, S; Paliukhovich, I; van der Schors, R C; van Nierop, P; Smit, A B; Philippens, I H C H M

    2016-01-15

    Chronic exposure to low-dose 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) in marmoset monkeys was used to model the prodromal stage of Parkinson's disease (PD), and to investigate mechanisms underlying disease progression and recovery. Marmosets were subcutaneously injected with MPTP for a period of 12weeks, 0.5mg/kg once per week, and clinical signs of Parkinsonism, motor- and non-motor behaviors were recorded before, during and after exposure. In addition, postmortem immunohistochemistry and proteomics analysis were performed. MPTP-induced parkinsonian clinical symptoms increased in severity during exposure, and recovered after MPTP administration was ended. Postmortem analyses, after the recovery period, revealed no alteration of the number and sizes of tyrosine hydroxylase (TH)-positive dopamine (DA) neurons in the substantia nigra. Also levels of TH in putamen and caudate nucleus were unaltered, no differences were observed in DA, serotonin or nor-adrenalin levels in the caudate nucleus, and proteomics analysis revealed no global changes in protein expression in these brain areas between treatment groups. Our findings indicate that parkinsonian symptoms can occur without detectable damage at the cellular or molecular level. Moreover, we show that parkinsonian symptoms may be reversible when diagnosed and treated early. Copyright © 2015 IBRO. Published by Elsevier Ltd. All rights reserved.

  19. Persistence Statements: Describing Digital Stickiness

    Directory of Open Access Journals (Sweden)

    John Kunze

    2017-08-01

    Full Text Available In this paper we present a draft vocabulary for making “persistence statements.” These are simple tools for pragmatically addressing the concern that anyone feels upon experiencing a broken web link. Scholars increasingly use scientific and cultural assets in digital form, but choosing which among many objects to cite for the long term can be difficult. There are few well-defined terms to describe the various kinds and qualities of persistence that object repositories and identifier resolvers do or don’t provide. Given an object’s identifier, one should be able to query a provider to retrieve human- and machine-readable information to help judge the level of service to expect and help gauge whether the identifier is durable enough, as a sort of long-term bet, to include in a citation. The vocabulary should enable providers to articulate persistence policies and set user expectations.

  20. Missed diagnosis-persistent delirium

    Directory of Open Access Journals (Sweden)

    Aseem Mehra

    2014-01-01

    Full Text Available Delirium is in general considered as an acute short lasting reversible neuropsychiatric syndrome. However, there is some evidence to suggest that in a small proportion of cases delirium may be a chronic or persistent condition. However, making this diagnosis requires clinical suspicion and ruling other differential diagnosis. In this report, we present a case of a 55-year-old man who had cognitive symptoms, psychotic symptoms and depressive symptoms along with persistent hypokalemia and glucose intolerance. He was seen by 3 psychiatrists with these symptoms and was initially diagnosed as having depressive disorder and later diagnosis of bipolar affective disorder (current episode mania, and psychosis were considered by the third psychiatrist. However, despite the presence of persistent neurocognitive deficits, evening worsening of symptoms, hypokalemia and glucose intolerance diagnosis of delirium was not suspected.

  1. Resonant persistent currents for ultracold bosons on a lattice ring

    Science.gov (United States)

    Arwas, Geva; Cohen, Doron; Hekking, Frank; Minguzzi, Anna

    2017-12-01

    We consider a one-dimensional bosonic gas on a ring lattice, in the presence of a localized barrier, and under the effect of an artificial gauge field. By means of exact diagonalization we study the persistent currents at varying interactions and barrier strength, for various values of lattice filling. While generically the persistent currents are strongly suppressed in the Mott insulator phase, they show a resonant behavior when the barrier strength becomes of the order of the interaction energy. We explain this phenomenon using an effective single-particle model. We show that this effect is robust at finite temperature, up the temperature scale where persistent currents vanish.

  2. Assessing persistence: Experiences documenting savings persistence under the California protocols

    Energy Technology Data Exchange (ETDEWEB)

    O' Drain, M.; Caulfield, T.O.

    1998-07-01

    As California enters the final stages of DSM evaluation and verification under regulation, documentation of energy savings persistence (persistence) takes center stage with respect to earnings claims. The California Protocols both simplify and complicate the process of measuring persistence. This paper discusses the California Protocols and the interaction between individual utility studies and cooperative statewide studies in fulfilling the requirements of the Protocols. It addresses measure effective useful life and measure technical degradation. The paper describes how California utilities are grappling with the practical issues of projecting effective useful life based on limited attrition data and speculative survival functions. Specifically, the paper discusses the difficulty of establishing meaningful survival functions for the breadth of measures represented in California DSM programs. Similarly, California utilities as a whole are attempting to establish exactly what measure technical degradation means, and whether it actually exists. The paper recounts the process, documents the approaches taken, and documents publicly available information on both retention based effective useful life and study based measure technical degradation. Finally, the authors propose improvements in the approach to persistence assessment.

  3. Energy Savings Lifetimes and Persistence

    Energy Technology Data Exchange (ETDEWEB)

    Hoffman, Ian M. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Schiller, Steven R. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Todd, Annika [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Billingsley, Megan A. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Goldman, Charles A. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Schwartz, Lisa C. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2016-02-01

    This technical brief explains the concepts of energy savings lifetimes and savings persistence and discusses how program administrators use these factors to calculate savings for efficiency measures, programs and portfolios. Savings lifetime is the length of time that one or more energy efficiency measures or activities save energy, and savings persistence is the change in savings throughout the functional life of a given efficiency measure or activity. Savings lifetimes are essential for assessing the lifecycle benefits and cost effectiveness of efficiency activities and for forecasting loads in resource planning. The brief also provides estimates of savings lifetimes derived from a national collection of costs and savings for electric efficiency programs and portfolios.

  4. Atmospheric transport of persistent semi-volatile organic chemicals to the Arctic and cold condensation in the mid-troposphere – Part 1: 2-D modeling in mean atmosphere

    Directory of Open Access Journals (Sweden)

    J. Ma

    2010-08-01

    Full Text Available In the first part of this study for revisiting the cold condensation effect on global distribution of semi-volatile organic chemicals (SVOCs, the atmospheric transport of SVOCs to the Arctic in the mid-troposphere in a mean meridional atmospheric circulation over the Northern Hemisphere was simulated by a two-dimensional (2-D atmospheric transport model. Results show that under the mean meridional atmospheric circulation the long-range atmospheric transport of SVOCs from warm latitudes to the Arctic occurs primarily in the mid-troposphere. Although major sources are in low and mid-latitude soils, the modeled air concentration of SVOCs in the mid-troposphere is of the same order as or higher than that near the surface, demonstrating that the mid-troposphere is an important pathway and reservoir of SVOCs. The cold condensation of the chemicals is also likely to take place in the mid-troposphere over a source region of SVOCs in warm low latitudes through interacting with clouds. We demonstrate that the temperature dependent vapour pressure and atmospheric degradation rate of SVOCs exhibit similarities between lower atmosphere over the Arctic and the mid-troposphere over a tropical region. Frequent occurrence of atmospheric ascending motion and convection over warm latitudes carry the chemicals to a higher altitude where some of these chemicals may partition onto solid or aqueous phase through interaction with atmospheric aerosols, cloud water droplets and ice particles, and become more persistent at lower temperatures. Stronger winds in the mid-troposphere then convey solid and aqueous phase chemicals to the Arctic where they sink by large-scale descending motion and wet deposition. Using calculated water droplet-air partitioning coefficient of several persistent organic semi-volatile chemicals under a mean air temperature profile from the equator to the North Pole we propose that clouds are likely important sorbing media for SVOCs and pathway of

  5. Persistent postoperative hiccups: a review

    DEFF Research Database (Denmark)

    Hansen, B J; Rosenberg, J

    1993-01-01

    . Numerous treatment modalities have been tried but with questionable success. Valproate has proven effective in two trials investigating persistent non-surgical hiccups. The simple application of a nasogastric tube may successfully treat the hiccups, possibly because of an alteration of the activity...

  6. Rhinophototherapy in persistent allergic rhinitis.

    Science.gov (United States)

    Bella, Zsolt; Kiricsi, Ágnes; Viharosné, Éva Dósa-Rácz; Dallos, Attila; Perényi, Ádám; Kiss, Mária; Koreck, Andrea; Kemény, Lajos; Jóri, József; Rovó, László; Kadocsa, Edit

    2017-03-01

    Previous published results have revealed that Rhinolight ® intranasal phototherapy is safe and effective in intermittent allergic rhinitis. The present objective was to assess whether phototherapy is also safe and effective in persistent allergic rhinitis. Thirty-four patients with persistent allergic rhinitis were randomized into two groups; twenty-five subjects completed the study. The Rhinolight ® group was treated with a combination of UV-B, UV-A, and high-intensity visible light, while the placebo group received low-intensity visible white light intranasal phototherapy on a total of 13 occasions in 6 weeks. The assessment was based on the diary of symptoms, nasal inspiratory peak flow, quantitative smell threshold, mucociliary transport function, and ICAM-1 expression of the epithelial cells. All nasal symptom scores and nasal inspiratory peak flow measurements improved significantly in the Rhinolight ® group relative to the placebo group and this finding persisted after 4 weeks of follow-up. The smell and mucociliary functions did not change significantly in either group. The number of ICAM-1 positive cells decreased non-significantly in the Rhinolight ® group. No severe side-effects were reported during the treatment period. These results suggest that Rhinolight ® treatment is safe and effective in persistent allergic rhinitis.

  7. Do some Firms Persistently Outperform?

    NARCIS (Netherlands)

    Capasso, M.|info:eu-repo/dai/nl/314016627; Cefis, E.|info:eu-repo/dai/nl/274516233; Frenken, K.|info:eu-repo/dai/nl/207145253

    2009-01-01

    This study analyses persistence in growth rates of the entire population of Dutch manufacturing firms. Previous literature on firm growth rates shows that extreme growth events are likely to be negatively correlated over time. A rebound effect following an extreme growth event questions the

  8. Do some firms persistently outperform?

    NARCIS (Netherlands)

    Capasso, M.; Cefis, E.; Frenken, K.

    2009-01-01

    This study analyses persistence in growth rates of the entire population of Dutch manufacturing firms. Previous literature on firm growth rates shows that extreme growth events are likely to be negatively correlated over time. A rebound effect following an extreme growth event questions the

  9. Child Abuse Potential: How Persistent?

    Science.gov (United States)

    Haapasalo, Jaana; Aaltonen, Terhi

    1999-01-01

    Compares mothers whose children had been under supervision of Child Protective Services (CPS) with comparison mothers for child abuse potential using Millner's Child Abuse Potential Inventory. CPS mothers scored significantly higher than the comparison mothers, indicating their persistent elevated child abuse potential; there was no significant…

  10. Coping with persistent environmental problems

    DEFF Research Database (Denmark)

    Varjopuro, Riku; Andrulewicz, Eugeniusz; Brandt, Urs Steiner

    2014-01-01

    ABSTRACT In this paper we focus on systemic delays in the Baltic Sea that cause the problem of eutrophication to persist. These problems are demonstrated in our study by addressing three types of delays: (1) decision delay: the time it takes for an idea or perceived need to be launched as a polic...

  11. Persistence

    DEFF Research Database (Denmark)

    Hansen, Kis Boisen

    2012-01-01

    The note shows an example of an architure for buildin g stand-alone program, where the programming language is object oriented and the databas system is a relational database system. Together with the notes is an example program.......The note shows an example of an architure for buildin g stand-alone program, where the programming language is object oriented and the databas system is a relational database system. Together with the notes is an example program....

  12. Grails Persistence with GORM and GSQL

    CERN Document Server

    Fischer, Robert

    2009-01-01

    Unique to the popular Grails web framework is its architecture. While other frameworks are built from the ground up, Grails leverages existing and proven technologies that already have advanced functionality built in. One of the key technologies in this architecture is Hibernate, on top of which Grails builds its GORM (Grails Object Relational Mapping) model layer. This provides Grails a persistence solution. Published with the developer in mind, firstPress technical briefs explore emerging technologies that have the potential to be critical for tomorrow's industry. Apress keeps developers one

  13. Inflation persistence on Services and Regulated Goods in Costa Rica

    Directory of Open Access Journals (Sweden)

    Jorge León Murillo

    2014-11-01

    Full Text Available The present document studies the degree of inflation persistence and price stickiness across different categories in the Costa Rican Consumer Price index (CPI, using disaggregate and aggregate data, with a particular focus in the regulated and services prices. We adopt two approaches: The parametric approach is based in an autoregressive process with constant mean, and the structural approach is based on the estimation of the New Keynesian Hybrid Phillips Curve. We use different econometric techniques, as univariate and multivariate time series, and panel data methods. The evidence suggests that changes in prices and services regulated items have higher degrees of persistence in addition to presenting rigidities in the adjustment pattern. Also it was found that using disaggregate data the degree of inflation persistence is lower than the inflation persistence estimation of univariate models with aggregate data, and this tend to reduce excluding the regulated and services products prices.

  14. Firm Life Cycle, Book-Tax Differences and Earnings Persistence

    Directory of Open Access Journals (Sweden)

    Antonio Lopo Martinez

    2016-06-01

    Full Text Available The objective in this study is to show if the life cycle explains the relation between the Book-Tax Differences (BTDs and earnings persistence, as well as to inform on the future gains and their relation with the BTDs. Therefore, univariate tests were applied to verify the differences between the mean BTDS, life cycle stages and regression coefficient for the Earnings Before Income Tax (EBIT. The study focused on Brazilian publicly traded companies between 2009 and 2013. The results indicated that the control of earnings persistence was related with the stages of the life cycle. The information relevance of the life cycle and the Book-Tax Differences for earnings persistence is registered. In conclusion, the firm life cycle should be included in the analysis of the relation between the BTDs and earnings persistence. The evidence registered here is crucial to identify the quality of the earnings and incorporate them into earnings valuation models.

  15. Sequence-Dependent Persistence Length of Long DNA

    Science.gov (United States)

    Chuang, Hui-Min; Reifenberger, Jeffrey G.; Cao, Han; Dorfman, Kevin D.

    2017-12-01

    Using a high-throughput genome-mapping approach, we obtained circa 50 million measurements of the extension of internal human DNA segments in a 41 nm ×41 nm nanochannel. The underlying DNA sequences, obtained by mapping to the reference human genome, are 2.5-393 kilobase pairs long and contain percent GC contents between 32.5% and 60%. Using Odijk's theory for a channel-confined wormlike chain, these data reveal that the DNA persistence length increases by almost 20% as the percent GC content increases. The increased persistence length is rationalized by a model, containing no adjustable parameters, that treats the DNA as a statistical terpolymer with a sequence-dependent intrinsic persistence length and a sequence-independent electrostatic persistence length.

  16. Response of a simian immunodeficiency virus (SIVmac251 to raltegravir: a basis for a new treatment for simian AIDS and an animal model for studying lentiviral persistence during antiretroviral therapy

    Directory of Open Access Journals (Sweden)

    Greenhouse Jack

    2010-03-01

    Full Text Available Abstract Background In this study we successfully created a new approach to ART in SIVmac251 infected nonhuman primates. This drug regimen is entirely based on drugs affecting the pre-integration stages of replication and consists of only two nucleotidic/nucleosidic reverse transcriptase inhibitors (Nt/NRTIs and raltegravir, a promising new drug belonging to the integrase strand transfer inhibitor (INSTI class. Results In acutely infected human lymphoid CD4+ T-cell lines MT-4 and CEMx174, SIVmac251 replication was efficiently inhibited by raltegravir, which showed an EC90 in the low nanomolar range. This result was confirmed in primary macaque PBMCs and enriched CD4+ T cell fractions. In vivo monotherapy with raltegravir for only ten days resulted in reproducible decreases in viral load in two different groups of animals. When emtricitabine (FTC and tenofovir (PMPA were added to treatment, undetectable viral load was reached in two weeks, and a parallel increase in CD4 counts was observed. In contrast, the levels of proviral DNA did not change significantly during the treatment period, thus showing persistence of this lentiviral reservoir during therapy. Conclusions In line with the high conservation of the three main amino acids Y143, Q148 and N155 (responsible for raltegravir binding and molecular docking simulations showing similar binding modes of raltegravir at the SIVmac251 and HIV-1 IN active sites, raltegravir is capable of inhibiting SIVmac251 replication both in tissue culture and in vivo. This finding may help to develop effective ART regimens for the simian AIDS model entirely based on drugs adopted for treatment in humans. This ART-treated AIDS nonhuman primate model could be employed to find possible strategies for virus eradication from the body.

  17. Persistent Homology of Collaboration Networks

    Directory of Open Access Journals (Sweden)

    C. J. Carstens

    2013-01-01

    Full Text Available Over the past few decades, network science has introduced several statistical measures to determine the topological structure of large networks. Initially, the focus was on binary networks, where edges are either present or not. Thus, many of the earlier measures can only be applied to binary networks and not to weighted networks. More recently, it has been shown that weighted networks have a rich structure, and several generalized measures have been introduced. We use persistent homology, a recent technique from computational topology, to analyse four weighted collaboration networks. We include the first and second Betti numbers for the first time for this type of analysis. We show that persistent homology corresponds to tangible features of the networks. Furthermore, we use it to distinguish the collaboration networks from similar random networks.

  18. Search along persistent random walks

    Science.gov (United States)

    Friedrich, Benjamin M.

    2008-06-01

    Optimal search strategies and their implementations in biological systems are a subject of active research. Here we study a search problem which is motivated by the hunt of sperm cells for the egg. We ask for the probability for an active swimmer to find a target under the condition that the swimmer starts at a certain distance from the target. We find that success probability is maximal for a certain level of fluctuations characterized by the persistence length of the swimming path of the swimmer. We derive a scaling law for the optimal persistence length as a function of the initial target distance and search time by mapping the search on a polymer physics problem.

  19. Is Farm Management Skill Persistent?

    OpenAIRE

    Li, Xin; Paulson, Nicholas

    2014-01-01

    Farm management skills can affect farm managers' performance. In this article, farm management performance is analyzed based on yearly Illinois Farm Business Farm Management (FBFM) panel data across 6,760 farms from 1996 through 2011. Two out-of-sample measures of skill are used to analyze the ability of farm managers that consistently perform well over yearly and longer time horizons. Persistence tests show management skills are consistent and predictable. Results also suggest that the most ...

  20. The role of metabolism in bacterial persistence

    Directory of Open Access Journals (Sweden)

    Stephanie M. Amato

    2014-03-01

    Full Text Available Bacterial persisters are phenotypic variants with extraordinary tolerances toward antibiotics. Persister survival has been attributed to inhibition of essential cell functions during antibiotic stress, followed by reversal of the process and resumption of growth upon removal of the antibiotic. Metabolism plays a critical role in this process, since it participates in the entry, maintenance, and exit from the persister phenotype. Here, we review the experimental evidence that demonstrates the importance of metabolism to persistence, highlight the successes and potential for targeting metabolism in the search for anti-persister therapies, and discuss the current methods and challenges to understand persister physiology.

  1. Microbial Biofilms: Persisters, Tolerance and Dosing

    Science.gov (United States)

    Cogan, N. G.

    2005-03-01

    Almost all moist surfaces are colonized by microbial biofilms. Biofilms are implicated in cross-contamination of food products, biofouling, medical implants and various human infections such as dental cavities, ulcerative colitis and chronic respiratory infections. Much of current research is focused on the recalcitrance of biofilms to typical antibiotic and antimicrobial treatments. Although the polymer component of biofilms impedes the penetration of antimicrobials through reaction-diffusion limitation, this does not explain the observed tolerance, it merely delays the action of the agent. Heterogeneities in growth-rate also slow the eradication of the bacteria since most antimicrobials are far less effective for non-growing, or slowly growing bacteria. This also does not fully describe biofilm tolerance, since heterogeneities arr primairly a result of nutrient consumption. In this investigation, we describe the formation of `persister' cells which neither grow nor die in the presence of antibiotics. We propose that the cells are of a different phenotype than typical bacterial cells and the expression of the phenotype is regulated by the growth rate and the antibiotic concentration. We describe several experiments which describe the dynamics of persister cells and which motivate a dosing protocol that calls for periodic dosing of the population. We then introduce a mathematical model, which describes the effect of such a dosing regiment and indicates that the relative dose/withdrawal times are important in determining the effectiveness of such a treatment. A reduced model is introduced and the similar behavior is demonstrated analytically.

  2. CHANGES IN HIPPOCAMPAL SPINE DENSITY AND PROTEIN KINASE C ISOFORMS FOLLOWING DEVELOPMENTAL EXPOSURE TO A MIXTURE OF PERSISTENT CHEMICALS.

    Science.gov (United States)

    Polychlorinated biphenyls (PCBs) offer a unique model to understand the major issues related to complex environmental mixtures of persistent chemicals. These pollutants are ubiquitous, persistent, bioaccumulate in human body through the food chain, and exist as mixtures of severa...

  3. Identification and Pathological Characterization of Persistent Asymptomatic Ebola Virus infection in Rhesus Monkeys

    Science.gov (United States)

    2017-05-12

    experimental animal models of EVD 19 . Yet, to 72 our knowledge, persistent EBOV infection has not been reported in NHP survivors of 73 experimental infection...280 developed based on partial clearance of EBOV from experimentally infected animals and 281 used to evaluate various candidate MCMs. Additionally...persists in immune-privileged sites was impossible due to the absence of a suitable 19 animal model. Here we detect persistent EBOV replication with

  4. Mechanisms of viral clearance and persistence.

    Science.gov (United States)

    Borrow, P

    1997-01-01

    Using examples predominantly drawn from study of the lymphocytic choriomeningitis virus (LCMV) model system, this review describes the mechanisms involved in control of virus infections by the cell-mediated immune response, and some of the different strategies viruses have evolved to evade such immune clearance so that they can persist in their hosts. The important role played by the CD8+ cytotoxic lymphocyte (CTL) response in clearance of many systemic virus infections is discussed; and it is emphasized that although CD8+ CTL are classically thought of as lymphocytes which mediate lysis of virus-infected target cells, the principal mechanism by which CD8+ T cells effect clearance of persistent and many acute virus infections via production of antiviral cytokines such as tumour necrosis factor-alpha and interferon-gamma, not via destruction of virus-producing cells. To avoid immune-mediated clearance, viruses frequently use a combination of several different strategies. These can be grouped into mechanisms for avoiding recognition by the immune response (such as establishing latent infections, replicating in immune-privileged sites, down-regulating the expression of immune recognition signals on the surface of infected cells, or undergoing antigenic variation); and mechanisms for suppressing the immune response. The latter include generalized immune suppression mechanisms, and strategies for more precisely disabling the specific immune response such as inducing tolerance or exhaustion of virus-specific CTL. The value of understanding both immune clearance mechanisms and viral evasion strategies in the rational design of immune-based therapies to combat persistent virus infections is discussed.

  5. MOOCs and Persistence: Definitions and Predictors

    Science.gov (United States)

    Evans, Brent J.; Baker, Rachel B.

    2016-01-01

    The chapter argues for redefining the term "persistence" as it relates to MOOCs and considers how different measures produce different results in the research; it closes with a review of research on persistence in MOOCs.

  6. Persistent junctional reciprocating tachycardia in the fetus

    NARCIS (Netherlands)

    Oudijk, M. A.; Stoutenbeek, P.; Sreeram, N.; Visser, G. H. A.; Meijboom, E. J.

    2003-01-01

    Persistent junctional reciprocating tachycardia (PJRT) tends to be a persistent arrhythmia and requires aggressive therapeutic management. Diagnosis and management of this infrequently occurring tachycardia in the fetus at an early stage is of importance for the prevention of congestive heart

  7. High Persister Mutants in Mycobacterium tuberculosis.

    Directory of Open Access Journals (Sweden)

    Heather L Torrey

    Full Text Available Mycobacterium tuberculosis forms drug-tolerant persister cells that are the probable cause of its recalcitrance to antibiotic therapy. While genetically identical to the rest of the population, persisters are dormant, which protects them from killing by bactericidal antibiotics. The mechanism of persister formation in M. tuberculosis is not well understood. In this study, we selected for high persister (hip mutants and characterized them by whole genome sequencing and transcriptome analysis. In parallel, we identified and characterized clinical isolates that naturally produce high levels of persisters. We compared the hip mutants obtained in vitro with clinical isolates to identify candidate persister genes. Genes involved in lipid biosynthesis, carbon metabolism, toxin-antitoxin systems, and transcriptional regulators were among those identified. We also found that clinical hip isolates exhibited greater ex vivo survival than the low persister isolates. Our data suggest that M. tuberculosis persister formation involves multiple pathways, and hip mutants may contribute to the recalcitrance of the infection.

  8. Persistence time of SIS infections in heterogeneous populations and networks.

    Science.gov (United States)

    Clancy, Damian

    2018-02-23

    For a susceptible-infectious-susceptible infection model in a heterogeneous population, we present simple formulae giving the leading-order asymptotic (large population) behaviour of the mean persistence time, from an endemic state to extinction of infection. Our model may be interpreted as describing an infection spreading through either (1) a population with heterogeneity in individuals' susceptibility and/or infectiousness; or (2) a heterogeneous directed network. Using our asymptotic formulae, we show that such heterogeneity can only reduce (to leading order) the mean persistence time compared to a corresponding homogeneous population, and that the greater the degree of heterogeneity, the more quickly infection will die out.

  9. Distributed Persistent Identifiers System Design

    Directory of Open Access Journals (Sweden)

    Pavel Golodoniuc

    2017-06-01

    Full Text Available The need to identify both digital and physical objects is ubiquitous in our society. Past and present persistent identifier (PID systems, of which there is a great variety in terms of technical and social implementation, have evolved with the advent of the Internet, which has allowed for globally unique and globally resolvable identifiers. PID systems have, by in large, catered for identifier uniqueness, integrity, and persistence, regardless of the identifier’s application domain. Trustworthiness of these systems has been measured by the criteria first defined by Bütikofer (2009 and further elaborated by Golodoniuc 'et al'. (2016 and Car 'et al'. (2017. Since many PID systems have been largely conceived and developed by a single organisation they faced challenges for widespread adoption and, most importantly, the ability to survive change of technology. We believe that a cause of PID systems that were once successful fading away is the centralisation of support infrastructure – both organisational and computing and data storage systems. In this paper, we propose a PID system design that implements the pillars of a trustworthy system – ensuring identifiers’ independence of any particular technology or organisation, implementation of core PID system functions, separation from data delivery, and enabling the system to adapt for future change. We propose decentralisation at all levels — persistent identifiers and information objects registration, resolution, and data delivery — using Distributed Hash Tables and traditional peer-to-peer networks with information replication and caching mechanisms, thus eliminating the need for a central PID data store. This will increase overall system fault tolerance thus ensuring its trustworthiness. We also discuss important aspects of the distributed system’s governance, such as the notion of the authoritative source and data integrity

  10. Resonant activation: a strategy against bacterial persistence

    Science.gov (United States)

    Fu, Yan; Zhu, Meng; Xing, Jianhua

    2010-03-01

    A bacterial colony may develop a small number of cells genetically identical to, but phenotypically different from, other normally growing bacteria. These so-called persister cells keep themselves in a dormant state and thus are insensitive to antibiotic treatment, resulting in serious problems of drug resistance. In this paper, we proposed a novel strategy to 'kill' persister cells by triggering them to switch, in a fast and synchronized way, into normally growing cells that are susceptible to antibiotics. The strategy is based on resonant activation (RA), a well-studied phenomenon in physics where the internal noise of a system can constructively facilitate fast and synchronized barrier crossings. Through stochastic Gilliespie simulation with a generic toggle switch model, we demonstrated that RA exists in the phenotypic switching of a single bacterium. Further, by coupling single cell level and population level simulations, we showed that with RA, one can greatly reduce the time and total amount of antibiotics needed to sterilize a bacterial population. We suggest that resonant activation is a general phenomenon in phenotypic transition, and can find other applications such as cancer therapy.

  11. A model for persistent hole burned spectra and hole growth kinetics that includes photoproduct absorption: Application to free base phthalocyanine in hyperquenched glassy ortho-dichlorobenzene at 5 K

    International Nuclear Information System (INIS)

    Reinot, T.; Dang, N.C.; Small, G.J.

    2003-01-01

    Persistent nonphotochemical and photochemical hole burning of the S 0 →S 1 origin absorption bands of chromophores in amorphous hosts such as glasses, polymers and proteins at low temperatures have been used to address a number of problems that range from structural disorder and configurational tunneling to excitation energy transfer and charge separation in photosynthetic complexes. Often the hole burned spectra are interfered by photoproduct (antihole) absorption. To date there has been no systematic approach to modeling hole burned spectra and the dispersive kinetics of zero-phonon hole growth that accounts for the antihole. A 'master' equation that does so is presented. A key ingredient of the equation is a time-dependent, two-dimensional site excitation frequency distribution function (SDF) of the zero-phonon lines. Prior to hole burning (t=0) the SDF is that of the educt sites. For t>0 the SDF describes both educt and photoproduct sites and allows for burning of the latter that revert to the educt sites from which they originate (light-induced hole filling). Our model includes linear electron-phonon coupling and the three distributions that lead to dispersive hole growth kinetics, the most important of which is the distribution for the parameter λ associated with tunneling between the bistable configurations of the chromophore-host system that are interconverted by hole burning. The master equation is successfully applied to free base phthalocyanine (Pc) in hyperquenched glassy ortho-dichlorobenzene (DCB) at 5 K. The mechanism of hole burning is photochemical and involves tautomerization of the two protons at the center of the macrocycle (Pc) that occurs in the S 1 (Q x ) and/or T 1 (Q x ) state of Pc. A single set of parameter values (some of which are determined directly from the hole burned spectra) provides a satisfactory description of the dependence of the hole burned spectra and hole growth kinetics on the location of the burn frequency within the

  12. Persistent spin helices in 2D electron systems

    Science.gov (United States)

    Kozulin, A. S.; Malyshev, A. I.; Konakov, A. A.

    2017-03-01

    We present a theoretical investigation of persistent spin helices in two-dimensional electron systems with spin-orbit coupling. For this purpose, we consider a single-particle effective mass Hamiltonian with a generalized linear-in- k spin-orbit coupling term corresponding to a quantum well grown in an arbitrary crystallographic direction, and derive the general condition for the formation of the persistent spin helix. This condition applied for the Hamiltonians describing quantum wells with different growth directions indicates the possibility of existence of the persistent spin helix in a wide class of 2D systems apart from the [001] model with equal Rashba and Dresselhaus spin-orbit coupling strengths and the [110] Dresselhaus model.

  13. Immune persistence after pertussis vaccination.

    Science.gov (United States)

    Chen, Zhiyun; He, Qiushui

    2017-04-03

    Pertussis is one of the most prevalent vaccine-preventable diseases worldwide. The true infection rate is significantly higher than the reported incidence rate. An increased prevalence of pertussis in older populations has been found, mainly caused by waning immunity after vaccination. Vaccine-induced immunity differs due to variation in vaccine content, schedule and coverage. Protection following acellular pertussis vaccines has been suggested to wane faster than whole cell pertussis vaccines. However, long-term immune persistence of whole cell pertussis vaccines may be confounded by a progressive acquisition of natural immunity. The World Health Organization has recommended that a switch from whole cell to acellular pertussis vaccines for primary immunization in infants should only be considered if additional periodic boosters or maternal immunization can be ensured and sustained in the national immunization schedules. In this review, we present data on immune persistence after different pertussis vaccinations and compare the findings from countries with different vaccination strategies. Future aspects in serological studies are briefly discussed.

  14. The structure and stability of persistence modules

    CERN Document Server

    Chazal, Frédéric; Glisse, Marc; Oudot, Steve

    2016-01-01

    This book is a comprehensive treatment of the theory of persistence modules over the real line. It presents a set of mathematical tools to analyse the structure and to establish the stability of such modules, providing a sound mathematical framework for the study of persistence diagrams. Completely self-contained, this brief introduces the notion of persistence measure and makes extensive use of a new calculus of quiver representations to facilitate explicit computations. Appealing to both beginners and experts in the subject, The Structure and Stability of Persistence Modules provides a purely algebraic presentation of persistence, and thus complements the existing literature, which focuses mainly on topological and algorithmic aspects.

  15. Environmental Persistence Influences Infection Dynamics for a Butterfly Pathogen.

    Directory of Open Access Journals (Sweden)

    Dara A Satterfield

    Full Text Available Many pathogens, including those infecting insects, are transmitted via dormant stages shed into the environment, where they must persist until encountering a susceptible host. Understanding how abiotic conditions influence environmental persistence and how these factors influence pathogen spread are crucial for predicting patterns of infection risk. Here, we explored the consequences of environmental transmission for infection dynamics of a debilitating protozoan parasite (Ophryocystis elektroscirrha that infects monarch butterflies (Danaus plexippus. We first conducted an experiment to observe the persistence of protozoan spores exposed to natural conditions. Experimental results showed that, contrary to our expectations, pathogen doses maintained high infectivity even after 16 days in the environment, although pathogens did yield infections with lower parasite loads after environmental exposure. Because pathogen longevity exceeded the time span of our experiment, we developed a mechanistic model to better explore environmental persistence for this host-pathogen system. Model analysis showed that, in general, longer spore persistence led to higher infection prevalence and slightly smaller monarch population sizes. The model indicated that typical parasite doses shed onto milkweed plants must remain viable for a minimum of 3 weeks for prevalence to increase during the summer-breeding season, and for 11 weeks or longer to match levels of infection commonly reported from the wild, assuming moderate values for parasite shedding rate. Our findings showed that transmission stages of this butterfly pathogen are long-lived and indicated that this is a necessary condition for the protozoan to persist in local monarch populations. This study provides a modeling framework for future work examining the dynamics of an ecologically important pathogen in an iconic insect.

  16. comK Prophage Junction Fragments as Markers for Listeria monocytogenes Genotypes Unique to Individual Meat and Poultry Processing Plants and a Model for Rapid Niche-Specific Adaptation, Biofilm Formation, and Persistence ▿ †

    Science.gov (United States)

    Verghese, Bindhu; Lok, Mei; Wen, Jia; Alessandria, Valentina; Chen, Yi; Kathariou, Sophia; Knabel, Stephen

    2011-01-01

    Different strains of Listeria monocytogenes are well known to persist in individual food processing plants and to contaminate foods for many years; however, the specific genotypic and phenotypic mechanisms responsible for persistence of these unique strains remain largely unknown. Based on sequences in comK prophage junction fragments, different strains of epidemic clones (ECs), which included ECII, ECIII, and ECV, were identified and shown to be specific to individual meat and poultry processing plants. The comK prophage-containing strains showed significantly higher cell densities after incubation at 30°C for 48 h on meat and poultry food-conditioning films than did strains lacking the comK prophage (P Listeria's rapid niche adaptation, biofilm formation, persistence, and subsequent transmission to foods. Also, comK prophage junction fragment sequences may permit accurate tracking of persistent strains back to and within individual food processing operations and thus allow the design of more effective intervention strategies to reduce contamination and enhance food safety. PMID:21441318

  17. comK prophage junction fragments as markers for Listeria monocytogenes genotypes unique to individual meat and poultry processing plants and a model for rapid niche-specific adaptation, biofilm formation, and persistence.

    Science.gov (United States)

    Verghese, Bindhu; Lok, Mei; Wen, Jia; Alessandria, Valentina; Chen, Yi; Kathariou, Sophia; Knabel, Stephen

    2011-05-01

    Different strains of Listeria monocytogenes are well known to persist in individual food processing plants and to contaminate foods for many years; however, the specific genotypic and phenotypic mechanisms responsible for persistence of these unique strains remain largely unknown. Based on sequences in comK prophage junction fragments, different strains of epidemic clones (ECs), which included ECII, ECIII, and ECV, were identified and shown to be specific to individual meat and poultry processing plants. The comK prophage-containing strains showed significantly higher cell densities after incubation at 30°C for 48 h on meat and poultry food-conditioning films than did strains lacking the comK prophage (P Listeria's rapid niche adaptation, biofilm formation, persistence, and subsequent transmission to foods. Also, comK prophage junction fragment sequences may permit accurate tracking of persistent strains back to and within individual food processing operations and thus allow the design of more effective intervention strategies to reduce contamination and enhance food safety.

  18. Persistent cough in an adolescent.

    Science.gov (United States)

    Stein, M T; Harper, G; Chen, J

    1999-12-01

    Jessica, a 14-year-old girl with a history of asthma, went to her pediatrician's office because of a persistent cough. She had been coughing for at least 3 months with occasional cough-free periods of less than a few days. The cough was nonproductive and was not accompanied by fever, rhinorrhea, or facial or chest pain. Jessica and her mother observed that the cough increased with exercise and typically was not present during sleep. She has used two metered-dose inhalers--albuterol and cromolyn--without any change in the cough pattern. For the past 5 years, Jessica has had mild asthma responsive to albuterol. She enjoys running on the cross-country team, soccer, and dancing. She is an average student and denies any change in academic performance. She has never been hospitalized or had an emergency department visit for asthma or pneumonia. There has been no recent travel or exposure to a person with a chronic productive cough, tobacco smoke, or a live-in pet. Jessica lives with her mother and younger sister in a 10-year-old, carpeted apartment without any evidence of mold or recent renovation. In the process of taking the history, the pediatrician noticed that Jessica coughed intermittently, with two or three coughs during each episode. At times, the cough was harsh; at other times, it was a quiet cough, as if she were clearing her throat. She was cooperative, without overt anxiety or respiratory distress. After a complete physical examination with normal findings, the pediatrician interviewed Jessica and her mother alone. Jessica's parents had been divorced for the past 6 years. She lived with her mother but visited her father, and his new family with two young children, every weekend. She spoke about this arrangement comfortably and said that she loved her father and mother but didn't like the tension she experienced at her father's home. "I don't like adults arguing when kids are around." When asked why she thought the cough persisted so long, she commented in a

  19. Persistent Organic Pollutants and Type 2 Diabetes

    DEFF Research Database (Denmark)

    Wu, Hongyu; Bertrand, Kimberly A; Choi, Anna L

    2013-01-01

    BACKGROUND: Prospective data regarding persistent organic pollutants (POPs) and risk of type 2 diabetes (T2D) are limited, and the results for individual POPs are not entirely consistent across studies. OBJECTIVES: To prospectively examine plasma POP concentrations in relation to incident T2D...... and total PCBs, respectively. CONCLUSIONS: These findings support an association between POP exposure and the risk of type 2 diabetes.......-1990 and participated in two case-control studies in the Nurses' Health Study. We identified 48 incident T2D cases through June 30, 2008. We conducted a literature search in MEDLINE and EMBASE through December 2011 to identify prospective studies on POPs in relation to diabetes. We used a fixed-effects model...

  20. Rev Variation during Persistent Lentivirus Infection

    Directory of Open Access Journals (Sweden)

    Karin S. Dorman

    2011-01-01

    Full Text Available The ability of lentiviruses to continually evolve and escape immune control is the central impediment in developing an effective vaccine for HIV-1 and other lentiviruses. Equine infectious anemia virus (EIAV is considered a useful model for immune control of lentivirus infection. Virus-specific cytotoxic T lymphocytes (CTL and broadly neutralizing antibody effectively control EIAV replication during inapparent stages of disease, but after years of low-level replication, the virus is still able to produce evasion genotypes that lead to late re-emergence of disease. There is a high rate of genetic variation in the EIAV surface envelope glycoprotein (SU and in the region of the transmembrane protein (TM overlapped by the major exon of Rev. This review examines genetic and phenotypic variation in Rev during EIAV disease and a possible role for Rev in immune evasion and virus persistence.

  1. Persistent Factors Facilitating Excellence in Research Environments

    DEFF Research Database (Denmark)

    Kalpazidou Schmidt, Evanthia; Graversen, Ebbe Krogh

    2018-01-01

    as in the framework of the environments, influencing research performance and identifies persistent factors in dynamic and innovative research environments. The findings add to our understanding of how to improve the overall ecology of knowledge production and create optimal conditions that support research......The paper identifies robust and time-invariant features that characterise dynamic and innovative research environments. It takes as its point of departure the results of an empirical study conducted in 2002, which identified the common characteristics of 15 dynamic and innovative public research...... environments, and focusses on their development by revisiting the environments after more than a decade, hence mapping them in the current research landscape. Based on a model for studies of research environments, constructed and used in the Nordic countries, the paper maps elements internal as well...

  2. 'Dicty dynamics': Dictyostelium motility as persistent random motion

    DEFF Research Database (Denmark)

    Li, Liang; Cox, Edward C; Flyvbjerg, Henrik

    2011-01-01

    to the amoeba's direction of motion. This motion propels the amoeba with a random periodic left–right waddle in a direction that has a long persistence time. The model fully accounts for the statistics of the experimental trajectories, including velocity power spectra and auto-correlations, non...

  3. QUANTIFICATION OF TRANSGENIC PLANT MARKER GENE PERSISTENCE IN THE FIELD

    Science.gov (United States)

    Methods were developed to monitor persistence of genomic DNA in decaying plants in the field. As a model, we used recombinant neomycin phosphotransferase II (rNPT-II) marker genes present in genetically engineered plants. Polymerase chain reaction (PCR) primers were designed, com...

  4. Security Evaluation of the Cyber Networks under Advanced Persistent Threats

    NARCIS (Netherlands)

    Yang, L.; Li, Pengdeng; Yang, Xiaofan; Tang, Yuan Yan

    2017-01-01

    Advanced persistent threats (APTs) pose a grave threat to cyberspace, because they deactivate all the conventional cyber defense mechanisms. This paper addresses the issue of evaluating the security of the cyber networks under APTs. For this purpose, a dynamic model capturing the APT-based

  5. Persistence of antimuscarinic drug use

    DEFF Research Database (Denmark)

    Brostrøm, Søren; Hallas, Jesper

    2009-01-01

    PURPOSE: Evidence suggests antimuscarinic drugs for the overactive-bladder syndrome only confer modest improvements in quality of life. We wanted to describe the persistence of therapy, including an extended analysis beyond the 1-year follow-up employed in other studies. METHODS: All prescriptions...... for drugs in ATC category G04BD were retrieved for the period 1999-2006 from a regional database with complete capture of all reimbursed prescriptions. Kaplan-Meyer curves were generated for duration of treatment for each substance and analyzed for determinants of termination. RESULTS: With the exception...... of trospium chloride, all drugs had continuation rates of less than 50% at 6 months, less than 25% at 1 year, and less than 10% at 2 years and longer. Trospium chloride, however, exhibited continuation rates of 46% at 6 months, 36% at 1 year, 22% at 2 years, and 16% at 3 years. CONCLUSIONS: In a setting...

  6. Persistence Mechanisms of Conjugative Plasmids

    DEFF Research Database (Denmark)

    Bahl, Martin Iain; Hansen, Lars H.; Sørensen, Søren Johannes

    2009-01-01

    maintenance in the host cell. These importantly include the ability to self-mobilize in a process termed conjugative transfer, which may occur across species barriers. Other plasmid stabilizing mechanisms include the multimer resolution system, active partitioning, and post-segregational-killing of plasmid......Are plasmids selfish parasitic DNA molecules or an integrated part of the bacterial genome? This chapter reviews the current understanding of the persistence mechanisms of conjugative plasmids harbored by bacterial cells and populations. The diversity and intricacy of mechanisms affecting...... the successful propagation and long-term continued existence of these extra-chromosomal elements is extensive. Apart from the accessory genetic elements that may provide plasmid-harboring cells a selective advantage, special focus is placed on the mechanisms conjugative plasmids employ to ensure their stable...

  7. Dematerialization: Variety, caution, and persistence.

    Science.gov (United States)

    Ausubel, Jesse H; Waggoner, Paul E

    2008-09-02

    Dematerialization, represented by declining consumption per GDP of energy or of goods, offers some hope for rising environmental quality with development. The declining proportion of income spent on staples as affluence grows, which income elasticity <1.0 measures, makes dematerialization widespread. Further, as learning improves efficiency of resource use, the intensity of environmental impact per production of staples often declines. We observe that combinations of low income elasticity for staples and of learning by producers cause a variety of dematerializations and declining intensities of impact, from energy use and carbon emission to food consumption and fertilizer use, globally and in countries ranging from the United States and France to China, India, Brazil, and Indonesia. Because dematerialization and intensity of impact are ratios of parameters that may be variously defined and are sometimes difficult to estimate, their fluctuations must be interpreted cautiously. Nevertheless, substantial declining intensity of impact, and especially, dematerialization persisted between 1980 and 2006.

  8. Psychoacoustic classification of persistent tinnitus.

    Science.gov (United States)

    Suzuki, Flavia Alencar de Barros; Suzuki, Fabio Akira; Onishi, Ektor Tsuneo; Penido, Norma Oliveira

    2017-08-01

    Tinnitus is a difficult to treat symptom, with different responses in patients. It is classified in different ways, according to its origin and associated diseases. to propose a single and measurable classification of persistent tinnitus, through its perception as sounds of nature or of daily life and its comparison with pure tone or noise, of high or low pitch, presented to the patient by audiometer sound. A total of 110 adult patients, of both genders, treated at the Tinnitus Outpatient Clinic, were enrolled according to the inclusion and exclusion criteria. Otorhinolaryngologic and Audiological, Pitch Matching and Loudness, Visual Analog Scale, Tinnitus Handicap Inventory and Minimum Masking Level assessments were performed. In these 110 patients, 181 tinnitus complaints were identified accordingly to type and ear, with 93 (51%) Pure Tone, and 88 (49%) Noise type; 19 at low and 162 at high frequency; with a mean in the Pure Tone of 5.47 in the Visual Analog Scale and 12.31 decibel in the Loudness and a mean in the Noise of 6.66 and 10.51 decibel. For Tinnitus Handicap Inventory and Minimum Masking Level, the 110 patients were separated into three groups with tinnitus, Pure Tone, Noise and multiple. Tinnitus Handicap Inventory higher in the group with multiple tinnitus, of 61.38. Masking noises such as White Noise and Narrow Band were used for the Minimum Masking Level at the frequencies of 500 and 6000Hz. There was a similarity between the Pure Tone and Multiple groups. In the Noise group, different responses were found when Narrow Band was used at low frequency. classifying persistent tinnitus as pure tone or noise, present in high or low frequency and establishing its different characteristics allow us to know its peculiarities and the effects of this symptom in patients' lives. Copyright © 2017 Associação Brasileira de Otorrinolaringologia e Cirurgia Cérvico-Facial. Published by Elsevier Editora Ltda. All rights reserved.

  9. Living with persistent rheumatoid arthritis: a BARFOT study.

    Science.gov (United States)

    Bala, Sidona-Valentina; Samuelson, Karin; Hagell, Peter; Fridlund, Bengt; Forslind, Kristina; Svensson, Björn; Thomé, Bibbi

    2017-09-01

    To describe and understand the meaning of living with persistent rheumatoid arthritis. A considerable number of patients with rheumatoid arthritis live with an ongoing active and symptomatic illness despite access to potent antirheumatic treatment. There is, however, a lack of knowledge about the meaning of living with this severe long-term illness, defined as persistent rheumatoid arthritis. A descriptive design based on a hermeneutic phenomenological method was used. Ten adults with persistent rheumatoid arthritis and at least five years disease duration were interviewed. The interviews were analysed according to van Manen's method. Living with persistent rheumatoid arthritis revealed four overall themes: an existence dominated by painful symptoms and treatment, radical changes and limitations in one's life, a continual struggle to cope with one's life and to master the illness, and a dependency on those who are close by and the world around. The lifeworld was affected to a varying extent and in various ways by the illness but also by the dependence on its treatment and care that was not experienced as sufficiently meeting needs in terms of security, access to and coordination of care as well as team and rehabilitation services. Persistent rheumatoid arthritis and its treatment entail a radical effect on the person's life and quality of life. Current ordinary rheumatology care does not seem to meet the individual needs of the person with persistent rheumatoid arthritis in an optimal way. A greater knowledge about and understanding of the person who lives with persistent rheumatoid arthritis is important for facilitating the development of care and the relief of suffering. A holistic alternative to conventional clinical practice, such as person-centred care, could be tested as an innovative model of care. Our findings might serve as material for educational and counselling purposes for healthcare professionals. © 2016 John Wiley & Sons Ltd.

  10. The Persistence of a Slow Manifold with Bifurcation

    DEFF Research Database (Denmark)

    Kristiansen, Kristian Uldall; Palmer, P.; Robert, M.

    2012-01-01

    his paper considers the persistence of a slow manifold with bifurcation in a slow-fast two degree of freedom Hamiltonian system. In particular, we consider a system with a supercritical pitchfork bifurcation in the fast space which is unfolded by the slow coordinate. The model system is motivated...... by tethered satellites. It is shown that an almost full measure subset of a neighborhood of the slow manifold's normally elliptic branches persists in an adiabatic sense. We prove this using averaging and a blow-up near the bifurcation....

  11. Persistence with denosumab and persistence with oral bisphosphonates for the treatment of postmenopausal osteoporosis: a retrospective, observational study, and a meta-analysis.

    Science.gov (United States)

    Karlsson, L; Lundkvist, J; Psachoulia, E; Intorcia, M; Ström, O

    2015-10-01

    The objectives of this study were to estimate persistence with denosumab and put these results in context by conducting a review of persistence with oral bisphosphonates. Persistence with denosumab was found to be higher than with oral bisphosphonates. This study had two objectives: to analyse persistence in Swedish women initiating denosumab for treatment of postmenopausal osteoporosis (PMO) and to put these findings in context by conducting a literature review and meta-analysis of persistence data for oral bisphosphonates. The study used the Swedish Prescribed Drug Register and included women aged at least 50 years initiating denosumab between May 2010 and July 2012. One injection of denosumab was defined as 6-month persistence. Women were considered persistent for another 6 months if they filled their next prescription within 6 months + 56 days and survival analysis applied to the data. A literature search was conducted in PubMed to identify retrospective studies of persistence with oral bisphosphonates and pooled persistence estimates were calculated using a random-effects model. The study identified 2,315 women who were incident denosumab users. Mean age was 74 years and 61% had been previously treated for PMO. At 12 and 24 months, persistence with denosumab was 83% (95% CI, 81-84%) and 62% (95% CI, 60-65%), respectively. The literature search identified 40 articles for inclusion in the meta-analysis. At 12 and 24 months, persistence with oral bisphosphonates ranged from 10% to 78% and from 16% to 46%, with pooled estimates of 45% and 30%, respectively. These data from the Swedish Prescribed Drug Register and literature review suggest that persistence was higher with denosumab than with oral bisphosphonates.

  12. The Persistence of Abnormal Returns: Analysis of Polish Manufacturing Industry

    Directory of Open Access Journals (Sweden)

    Marcin Puziak

    2017-06-01

    Full Text Available The ultimate goal of a company is to build the enterprise value, which is achievable thanks to abnormal profits generated in particular period. Moreover, firms are expected to take measures to maintain abnormal profit in the future. On the other hand, abnormal profits attract competitors, who increase competition and as a result abnormal profits disappear. The persistence of profit is a term that describes a situation, when the company is successful in maintaining the abnormal profit over time. The main aim of this paper is to investigate the persistence of abnormal profit in Polish manufacturing sector. In other words, the question is whether Polish manufacturing companies are able to maintain their abnormal profits over time. The persistence of abnormal profits is investigated using dynamic panel model with generalized method-of-moments estimators. The method is applied to a panel of 5303 Polish companies from manufacturing sector observed over the period 2006-2014. This paper contributes to the existing literature in two ways. First, analysis is performed for developing country. Second, analysis is performed both at the level of entire sector and at division level. Three main conclusions can be drawn from the conducted research: there are significant differences between profit rates within the same industry at division level; estimated persistence of abnormal profit coefficients are at moderate level; there are substantial differences between estimated persistence of profit coefficients for divisions in the same industry.

  13. Coral reef fish populations can persist without immigration

    Science.gov (United States)

    Salles, Océane C.; Maynard, Jeffrey A.; Joannides, Marc; Barbu, Corentin M.; Saenz-Agudelo, Pablo; Almany, Glenn R.; Berumen, Michael L.; Thorrold, Simon R.; Jones, Geoffrey P.; Planes, Serge

    2015-01-01

    Determining the conditions under which populations may persist requires accurate estimates of demographic parameters, including immigration, local reproductive success, and mortality rates. In marine populations, empirical estimates of these parameters are rare, due at least in part to the pelagic dispersal stage common to most marine organisms. Here, we evaluate population persistence and turnover for a population of orange clownfish, Amphiprion percula, at Kimbe Island in Papua New Guinea. All fish in the population were sampled and genotyped on five occasions at 2-year intervals spanning eight years. The genetic data enabled estimates of reproductive success retained in the same population (reproductive success to self-recruitment), reproductive success exported to other subpopulations (reproductive success to local connectivity), and immigration and mortality rates of sub-adults and adults. Approximately 50% of the recruits were assigned to parents from the Kimbe Island population and this was stable through the sampling period. Stability in the proportion of local and immigrant settlers is likely due to: low annual mortality rates and stable egg production rates, and the short larval stages and sensory capacities of reef fish larvae. Biannual mortality rates ranged from 0.09 to 0.55 and varied significantly spatially. We used these data to parametrize a model that estimated the probability of the Kimbe Island population persisting in the absence of immigration. The Kimbe Island population was found to persist without significant immigration. Model results suggest the island population persists because the largest of the subpopulations are maintained due to having low mortality and high self-recruitment rates. Our results enable managers to appropriately target and scale actions to maximize persistence likelihood as disturbance frequencies increase. PMID:26582017

  14. Coral reef fish populations can persist without immigration

    KAUST Repository

    Salles, Océane C.

    2015-11-18

    Determining the conditions under which populations may persist requires accurate estimates of demographic parameters, including immigration, local reproductive success, and mortality rates. In marine populations, empirical estimates of these parameters are rare, due at least in part to the pelagic dispersal stage common to most marine organisms. Here, we evaluate population persistence and turnover for a population of orange clownfish, Amphiprion percula, at Kimbe Island in Papua New Guinea. All fish in the population were sampled and genotyped on five occasions at 2-year intervals spanning eight years. The genetic data enabled estimates of reproductive success retained in the same population (reproductive success to self-recruitment), reproductive success exported to other subpopulations (reproductive success to local connectivity), and immigration and mortality rates of sub-adults and adults. Approximately 50% of the recruits were assigned to parents from the Kimbe Island population and this was stable through the sampling period. Stability in the proportion of local and immigrant settlers is likely due to: low annual mortality rates and stable egg production rates, and the short larval stages and sensory capacities of reef fish larvae. Biannual mortality rates ranged from 0.09 to 0.55 and varied significantly spatially. We used these data to parametrize a model that estimated the probability of the Kimbe Island population persisting in the absence of immigration. The Kimbe Island population was found to persist without significant immigration. Model results suggest the island population persists because the largest of the subpopulations are maintained due to having low mortality and high self-recruitment rates. Our results enable managers to appropriately target and scale actions to maximize persistence likelihood as disturbance frequencies increase.

  15. Connectivity, cycles, and persistence thresholds in metapopulation networks.

    Directory of Open Access Journals (Sweden)

    Yael Artzy-Randrup

    2010-08-01

    Full Text Available Synthesising the relationships between complexity, connectivity, and the stability of large biological systems has been a longstanding fundamental quest in theoretical biology and ecology. With the many exciting developments in modern network theory, interest in these issues has recently come to the forefront in a range of multidisciplinary areas. Here we outline a new theoretical analysis specifically relevant for the study of ecological metapopulations focusing primarily on marine systems, where subpopulations are generally connected via larval dispersal. Our work determines the qualitative and quantitative conditions by which dispersal and network structure control the persistence of a set of age-structured patch populations. Mathematical modelling combined with a graph theoretic analysis demonstrates that persistence depends crucially on the topology of cycles in the dispersal network which tend to enhance the effect of larvae "returning home." Our method clarifies the impact directly due to network structure, but this almost by definition can only be achieved by examining the simplified case in which patches are identical; an assumption that we later relax. The methodology identifies critical migration routes, whose presence are vital to overall stability, and therefore should have high conservation priority. In contrast, "lonely links," or links in the network that do not participate in a cyclical component, have no impact on persistence and thus have low conservation priority. A number of other intriguing criteria for persistence are derived. Our modelling framework reveals new insights regarding the determinants of persistence, stability, and thresholds in complex metapopulations. In particular, while theoretical arguments have, in the past, suggested that increasing connectivity is a destabilizing feature in complex systems, this is not evident in metapopulation networks where connectivity, cycles, coherency, and heterogeneity all tend

  16. Dualities in Persistent (Co)Homology

    Energy Technology Data Exchange (ETDEWEB)

    de Silva, Vin; Morozov, Dmitriy; Vejdemo-Johansson, Mikael

    2011-09-16

    We consider sequences of absolute and relative homology and cohomology groups that arise naturally for a filtered cell complex. We establishalgebraic relationships between their persistence modules, and show that they contain equivalent information. We explain how one can use the existingalgorithm for persistent homology to process any of the four modules, and relate it to a recently introduced persistent cohomology algorithm. Wepresent experimental evidence for the practical efficiency of the latter algorithm.

  17. Persistence of contact allergy among Danish adults

    DEFF Research Database (Denmark)

    Nielsen, N H; Linneberg, A; Menné, T

    2001-01-01

    , the persistence of allergic contact sensitivity, defined as 1 or more positive patch tests in both surveys, was 71% (37 out of 52 subjects). Nickel allergy persisted in 79% (19 out of 24 subjects), while 60% (21 out of 35 subjects) had a positive patch test reaction to 1 or more allergens, other than nickel...... at least 1 positive patch test. Nickel allergy persisted in 79%. Allergen avoidance should probably be lifelong to prevent elicitation of contact dermatitis....

  18. Physical trust-based persistent authentication

    DEFF Research Database (Denmark)

    Fujita, Masahiro; Jensen, Christian D.; Arimura, Shiori

    2015-01-01

    Recently companies have applied two-factor user authentication. Persistent Authentication is one of the interesting authentication mechanisms to establish security and usability of two-factor authentication systems. However, there is room to improve its feasibility and usability. In this paper, we...... propose a new type of persistent authentication, called Persistent Authentication Based On physical Trust (PABOT). PABOT uses a context of “physical trust relationship” that is built by visual contact between users, and thus can offer a persistent authentication mechanism with better usability and higher...

  19. Treatment persistence in patients with rheumatoid arthritis and ankylosing spondylitis

    Directory of Open Access Journals (Sweden)

    Marina Amaral de Ávila Machado

    2016-01-01

    Full Text Available ABSTRACT OBJECTIVE To evaluate treatment persistence in patients with rheumatoid arthritis and ankylosing spondylitis who started therapies with disease-modifying antirheumatic drugs (DMARD and tumor necrosis factor blockers (anti-TNF drugs. METHODS This retrospective cohort study from July 2008 to September 2013 evaluated therapy persistence, which is defined as the period between the start of treatment until it is discontinued, allowing for an interval of up to 30 days between the prescription end and the start of the next prescription. Odds ratio (OR with 95% confidence intervals (95%CI were calculated by logistic regression models to estimate the patients’ chances of persisting in their therapies after the first and after the two first years of follow-up. RESULTS The study included 11,642 patients with rheumatoid arthritis – 2,241 of these started on anti-TNF drugs (+/-DMARD and 9,401 patients started on DMARD – and 1,251 patients with ankylosing spondylitis – 976 of them were started on anti-TNF drugs (+/-DMARD and 275 were started on DMARD. In the first year of follow-up, 63.5% of the patients persisted in their therapies with anti-TNF drugs (+/-DMARD and 54.1% remained using DMARD in the group with rheumatoid arthritis. In regards to ankylosing spondylitis, 79.0% of the subjects in anti-TNF (+/-DMARD group and 41.1% of the subjects in the DMARD group persisted with their treatments. The OR (95%CI for therapy persistence was 1.50 (1.34-1.67 for the anti-TNF (+/-DMARD group as compared with the DMARD group in the first year for the patients with rheumatoid arthritis, and 2.33 (1.74-3.11 for the patients with ankylosing spondylitis. A similar trend was observed at the end of the second year. CONCLUSIONS A general trend of higher rates of therapy persistence with anti-TNF drugs (+/-DMARD was observed as compared to DMARD in the study period. We observed higher persistence rates for anti-TNF drugs (+/-DMARD in patients with ankylosing

  20. Translating Romans: some persistent headaches

    Directory of Open Access Journals (Sweden)

    A.B. du Toit

    2010-07-01

    Full Text Available Translating Romans: some persistent headaches Gone are the days when it was axiomatic that expertise in biblical languages automatically qualified one as a Bible translator. In 1949, Ronald Knox, who for nine years conscientiously struggled with translating the Bible for his generation, published a booklet under the title The trials of a translator. At that stage Bible translation as the subject of scientific study was still in its infancy. Since then, research into the intricacies of communicating the biblical message in an authentic but understandable manner, has made significant progress (cf. Roberts, 2009. However, the frustrations of Bible translators, first of all to really understand what the biblical authors wanted to convey to their original addressees, and then to commu-nicate that message to their own targeted readers in a meaningful way, have not disappeared. In fact, the challenge to meet the vary-ing requirements of the multiple kinds of translation that are present-ly in vogue, has only increased.

  1. Persistence analysis of poliovirus on three different types of fomites.

    Science.gov (United States)

    Tamrakar, S B; Henley, J; Gurian, P L; Gerba, C P; Mitchell, J; Enger, K; Rose, J B

    2017-02-01

    The goal of this study was to explore various models for describing viral persistence (infectivity) on fomites and identify the best fit models. The persistence of poliovirus over time was studied on three different fomite materials: steel, cotton and plastic. Known concentrations of poliovirus type 1 were applied to the surface coupons in an indoor environment for various lengths of time. Viruses were recovered from the surfaces by vortexing in phosphate buffer. Seven different mathematical models of relative persistence over time were fit to the data, and the preferred model for each surface was selected based on the Bayesian information criterion. While the preferred model varied by fomite type, the virus showed a rapid initial decay on all of the fomite types, followed by a transition to a more gradual decay after about 4-8 days. Estimates of the time for 99% reduction ranged from 81 h for plastic to 143 h for cotton. A 6 log reduction of recoverable infectivity of poliovirus did not occur during the 3-week duration of the experiment for any of the fomites. In protected indoor environments poliovirus can remain infective for weeks. The models identified by this study can be used in risk assessments to identify appropriate strategies for managing this risk. © 2016 The Society for Applied Microbiology.

  2. Postnatal persistent infection with classical Swine Fever virus and its immunological implications.

    Directory of Open Access Journals (Sweden)

    Sara Muñoz-González

    might go unnoticed. In addition to the epidemiological and economic significance of persistent CSFV infection, this model could be useful for understanding the mechanisms of viral persistence.

  3. The Relationship of Loneliness and Social Support with College Freshmen's Academic Performance and Persistence

    Science.gov (United States)

    Nicpon, Megan Foley; Huser, Laura; Blanks, Elva Hull; Sollenberger, Sonja; Befort, Christie; Kurpius, Sharon E. Robinson

    2007-01-01

    Based on Tinto's (1993) model of academic persistence, this study investigated the relationship of loneliness, social support, and living arrangements with academic persistence decisions of 401 college freshmen. Participants completed a series of standardized instruments during class time. Social support was negatively related to loneliness and…

  4. Medical and sociodemographic factors predict persistent smoking after coronary events.

    Science.gov (United States)

    Sverre, Elise; Otterstad, Jan Erik; Gjertsen, Erik; Gullestad, Lars; Husebye, Einar; Dammen, Toril; Moum, Torbjørn; Munkhaugen, John

    2017-09-06

    Understanding the determinants of persistent smoking after a coronary event constitutes the basis of modelling interventions of smoking cessation in secondary prevention programs. We aim to identify the potentially modifiable medical, sociodemographic and psychosocial factors, comprising the study factors, associated with unfavourable risk factor control after CHD events. A cross-sectional explorative study used logistic regression analysis to investigate the association between study factors and smoking status in 1083 patients hospitalized with myocardial infarction and/or coronary revascularization. Hospital record data, a self-report questionnaire, clinical examination and blood samples were applied. At the index hospitalization, 390 patients were smoking and at follow-up after 2-36 months 167 (43%) of these had quit, while 230 reported persistent smoking. In adjusted analyses, unemployed or disability benefits (Odds ratio (OR) 4.1), low education (OR 3.5), longer smoking duration (OR 2.3) and not having ST-elevation myocardial infarction (STEMI) as index event (OR 2.3) were significantly associated with persistent smoking. Psychosocial factors at follow-up were not associated with persistent smoking. Smokers reported high motivation for cessation, with 68% wanting help to quit. Only 42% had been offered nicotine replacement therapy or other cessation aids. Smokers rated use of tobacco as the most important cause of their coronary disease (6.8 on a 1-10 Likert scale). Low socioeconomic status, prior duration of smoking, and not having STEMI as index event were associated with persisting smoking. Persistent smokers in this study seem to have an acceptable risk perception and were motivated to cease smoking, but needed assistance through cessation programs including prescription of pharmacological aids. Registered at ClinicalTrials.gov: NCT02309255 , registered retrospectively.

  5. Persistence of plasmid DNA in different soils

    African Journals Online (AJOL)

    STORAGESEVER

    2008-08-04

    Aug 4, 2008 ... Every 7 days 1 g of soil was taken, DNA purified from it and then that DNA was used for transformation with the E. coli DH5α competent cells and the results showed that DNA would persist till 35 days and it had transforming ability. Key words: Horizontal gene transfer, plasmid pUC18, persistence, abiotic.

  6. Mastering NServiceBus and persistence

    CERN Document Server

    Helton, Rich

    2014-01-01

    This book is intended for developers, designers, and architects alike who wish to build C# NServiceBus enterprise architectures and learn how ESB persists data and messages to help them attain their goals. No prior knowledge of persistence in NServiceBus is required.

  7. Persistence of Antibiotic Resistance Plasmids in Biofilms

    Science.gov (United States)

    2014-10-01

    wounds, facilitates the persistence of MDR plasmids in Acinetobacter baumannii , a problematic wound pathogen. Moreover, we have shown that plasmids...which plasmid persistence can improve in Acinetobacter baumannii and other wound pathogens when grown in biofilm environments. This project has the... Acinetobacter * baumannii ,!Klebsiella*pneumoniae,!Enterobacter*sp.,! and! Escherichia* coli! (Eardley! et! al.,! 2011;! Gaynes! &! Edwards,! 2005;! Murray

  8. Revealing trap depth distributions in persistent phosphors

    NARCIS (Netherlands)

    Van den Eeckhout, K.; Bos, A.J.J.; Poelman, D.; Smet, P.F.

    2013-01-01

    Persistent luminescence or afterglow is caused by a gradual release of charge carriers from trapping centers. The energy needed to release these charge carriers is determined by the trap depths. Knowledge of these trap depths is therefore crucial in the understanding of the persistent luminescence

  9. Persistent Identifiers as Boundary Objects

    Science.gov (United States)

    Parsons, M. A.; Fox, P. A.

    2017-12-01

    In 1989, Leigh Star and Jim Griesemer defined the seminal concept of `boundary objects'. These `objects' are what Latour calls `immutable mobiles' that enable communication and collaboration across difference by helping meaning to be understood in different contexts. As Star notes, they are a sort of arrangement that allow different groups to work together without (a priori) consensus. Part of the idea is to recognize and allow for the `interpretive flexibility' that is central to much of the `constructivist' approach in the sociology of science. Persistent Identifiers (PIDs) can clearly act as boundary objects, but people do not usually assume that they enable interpretive flexibility. After all, they are meant to be unambiguous, machine-interpretable identifiers of defined artifacts. In this paper, we argue that PIDs can fill at least two roles: 1) That of the standardized form, where there is strong agreement on what is being represented and how and 2) that of the idealized type, a more conceptual concept that allows many different representations. We further argue that these seemingly abstract conceptions actually help us implement PIDs more effectively to link data, publications, various other artifacts, and especially people. Considering PIDs as boundary objects can help us address issues such as what level of granularity is necessary for PIDs, what metadata should be directly associated with PIDs, and what purpose is the PID serving (reference, provenance, credit, etc.). In short, sociological theory can improve data sharing standards and their implementation in a way that enables broad interdisciplinary data sharing and reuse. We will illustrate this with several specific examples of Earth science data.

  10. Higgs-induced lepton flavor violation

    Energy Technology Data Exchange (ETDEWEB)

    Goudelis, Andreas; Lebedev, Oleg [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Park, Jae-hyeon [Technische Univ. Dresden (Germany). Inst. fuer Kern- und Teilchenphysik

    2011-11-15

    Due to the smallness of the lepton Yukawa couplings, higher-dimensional operators can give a significant contribution to the lepton masses. In this case, the lepton mass matrix and the matrix of lepton-Higgs couplings are misaligned leading to lepton flavor violation (LFV) mediated by the Standard Model Higgs boson. We derive model-independent bounds on the Higgs flavor violating couplings and quantify LFV in decays of leptons and electric dipole moments for a class of lepton-Higgs operators contributing to lepton masses. We find significant Higgs-mediated LFV effects, especially if they involve virtual {tau}'s. (orig.)

  11. Making web annotations persistent over time

    Energy Technology Data Exchange (ETDEWEB)

    Sanderson, Robert [Los Alamos National Laboratory; Van De Sompel, Herbert [Los Alamos National Laboratory

    2010-01-01

    As Digital Libraries (DL) become more aligned with the web architecture, their functional components need to be fundamentally rethought in terms of URIs and HTTP. Annotation, a core scholarly activity enabled by many DL solutions, exhibits a clearly unacceptable characteristic when existing models are applied to the web: due to the representations of web resources changing over time, an annotation made about a web resource today may no longer be relevant to the representation that is served from that same resource tomorrow. We assume the existence of archived versions of resources, and combine the temporal features of the emerging Open Annotation data model with the capability offered by the Memento framework that allows seamless navigation from the URI of a resource to archived versions of that resource, and arrive at a solution that provides guarantees regarding the persistence of web annotations over time. More specifically, we provide theoretical solutions and proof-of-concept experimental evaluations for two problems: reconstructing an existing annotation so that the correct archived version is displayed for all resources involved in the annotation, and retrieving all annotations that involve a given archived version of a web resource.

  12. Stochastic convergence of persistence landscapes and silhouettes

    Directory of Open Access Journals (Sweden)

    Frédéric Chazal

    2015-03-01

    Full Text Available Persistent homology is a widely used tool in Topological Data Analysis that encodes multi-scale topological information as a multiset of points in the plane called a persistence diagram. It is difficult to apply statistical theory directly to a random sample of diagrams. Instead, we summarize persistent homology with a persistence landscape, introduced by Bubenik, which converts a diagram into a well-behaved real-valued function. We investigate the statistical properties of landscapes, such as weak convergence of the average landscapes and convergence of the bootstrap. In addition, we introduce an alternate functional summary of persistent homology, which we call the silhouette, and derive an analogous statistical theory.

  13. On persistence interfaces for scientific data stores

    International Nuclear Information System (INIS)

    Malon, D.M.; May, E.N.

    1996-01-01

    A common dilemma among builders of large scientific data stores is whether to use a lightweight object persistence manager or a genuine object-oriented database. There are often good reasons to consider each of these strategies; a few are described in this paper. Too often, however, electing to use a lightweight approach has meant programming to an interface that is entirely different than that expected by commercial object-oriented databases. With the emergence of object database standards, it is possible to provide an interface to persistence managers that does not needlessly inhibit coexistence with (and, perhaps, eventual migration to) object-oriented databases. This paper describes an implementation of a substantial subset of the ODMG-93[1]C++ specification that allows clients to use many of today's lightweight object persistence managers through an interface that conforms to the ODMG standard. We also describe a minimal interface that persistence software should support in order to provide persistence services for ODMG implementations

  14. Transparent Persistence with Java Data Objects

    CERN Document Server

    Hrivnác, J

    2003-01-01

    Flexible and performant Persistency Service is a necessary component of any HEP Software Framework. The building of a modular, non-intrusive and performant persistency component have been shown to be very difficult task. In the past, it was very often necessary to sacrifice modularity to achieve acceptable performance. This resulted in the strong dependency of the overall Frameworks on their Persistency subsystems. Recent development in software technology has made possible to build a Persistency Service which can be transparently used from other Frameworks. Such Service doesn't force a strong architectural constraints on the overall Framework Architecture, while satisfying high performance requirements. Java Data Object standard (JDO) has been already implemented for almost all major databases. It provides truly transparent persistency for any Java object (both internal and external). Objects in other languages can be handled via transparent proxies. Being only a thin layer on top of a used database, JDO doe...

  15. Enantioselective Biotransformation of Chiral Persistent Organic Pollutants.

    Science.gov (United States)

    Zhang, Ying; Ye, Jing; Liu, Min

    2017-01-01

    Enantiomers of chiral compounds commonly undergo enantioselective transformation in most biologically mediated processes. As chiral persistent organic pollutants (POPs) are extensively distributed in the environment, differences between enantiomers in biotransformation should be carefully considered to obtain exact enrichment and specific health risks. This review provides an overview of in vivo biotransformation of chiral POPs currently indicated in the Stockholm Convention and their chiral metabolites. Peer-reviewed journal articles focused on the research question were thoroughly searched. A set of inclusion and exclusion criteria were developed to identify relevant studies. We mainly compared the results from different animal models under controlled laboratory conditions to show the difference between enantiomers in terms of distinct transformation potential. Interactions with enzymes involved in enantioselective biotransformation, especially cytochrome P450 (CYP), were discussed. Further research areas regarding this issue were proposed. Limited evidence for a few POPs has been found in 30 studies. Enantioselective biotransformation of α-hexachlorocyclohexane (α-HCH), chlordane, dichlorodiphenyltrichloroethane (DDT), heptachlor, hexabromocyclododecane (HBCD), polychlorinated biphenyls (PCBs), and toxaphene, has been investigated using laboratory mammal, fish, bird, and worm models. Tissue and excreta distributions, as well as bioaccumulation and elimination kinetics after administration of racemate and pure enantiomers, have been analyzed in these studies. Changes in enantiomeric fractions have been considered as an indicator of enantioselective biotransformation of chiral POPs in most studies. Results of different laboratory animal models revealed that chiral POP biotransformation is seriously affected by chirality. Pronounced results of species-, tissue-, gender-, and individual-dependent differences are observed in in vivo biotransformation of chiral POPs

  16. Monitoring of Biodistribution and Persistence of Conditionally Replicative Adenovirus in a Murine Model of Ovarian Cancer Using Capsid-Incorporated mCherry and Expression of Human Somatostatin Receptor Subtype 2 Gene

    Directory of Open Access Journals (Sweden)

    Igor P. Dmitriev

    2014-10-01

    Full Text Available A significant limiting factor to the human clinical application of conditionally replicative adenovirus (CRAd-based virotherapy is the inability to noninvasively monitor these agents and their potential persistence. To address this issue, we proposed a novel imaging approach that combines transient expression of the human somatostatin receptor (SSTR subtype 2 reporter gene with genetic labeling of the viral capsid with mCherry fluorescent protein. To test this dual modality system, we constructed the Ad5/3Δ24pIXcherry/SSTR CRAd and validated its capacity to generate fluorescent and nuclear signals in vitro and following intratumoral injection. Analysis of 64Cu-CB-TE2A-Y3-TATE biodistribution in mice revealed reduced uptake in tumors injected with the imaging CRAd relative to the replication-incompetent, Ad-expressing SSTR2 but significantly greater uptake compared to the negative CRAd control. Optical imaging demonstrated relative correlation of fluorescent signal with virus replication as determined by viral genome quantification in tumors. Positron emission tomography/computed tomography studies demonstrated that we can visualize radioactive uptake in tumors injected with imaging CRAd and the trend for greater uptake by standardized uptake value analysis compared to control CRAd. In the aggregate, the plasticity of our dual imaging approach should provide the technical basis for monitoring CRAd biodistribution and persistence in preclinical studies while offering potential utility for a range of clinical applications.

  17. Evolutionary dynamics for persistent cooperation in structured populations

    Science.gov (United States)

    Li, Yan; Liu, Xinsheng; Claussen, Jens Christian; Guo, Wanlin

    2015-06-01

    The emergence and maintenance of cooperative behavior is a fascinating topic in evolutionary biology and social science. The public goods game (PGG) is a paradigm for exploring cooperative behavior. In PGG, the total resulting payoff is divided equally among all participants. This feature still leads to the dominance of defection without substantially magnifying the public good by a multiplying factor. Much effort has been made to explain the evolution of cooperative strategies, including a recent model in which only a portion of the total benefit is shared by all the players through introducing a new strategy named persistent cooperation. A persistent cooperator is a contributor who is willing to pay a second cost to retrieve the remaining portion of the payoff contributed by themselves. In a previous study, this model was analyzed in the framework of well-mixed populations. This paper focuses on discussing the persistent cooperation in lattice-structured populations. The evolutionary dynamics of the structured populations consisting of three types of competing players (pure cooperators, defectors, and persistent cooperators) are revealed by theoretical analysis and numerical simulations. In particular, the approximate expressions of fixation probabilities for strategies are derived on one-dimensional lattices. The phase diagrams of stationary states, and the evolution of frequencies and spatial patterns for strategies are illustrated on both one-dimensional and square lattices by simulations. Our results are consistent with the general observation that, at least in most situations, a structured population facilitates the evolution of cooperation. Specifically, here we find that the existence of persistent cooperators greatly suppresses the spreading of defectors under more relaxed conditions in structured populations compared to that obtained in well-mixed populations.

  18. Haemophilus influenzae genome evolution during persistence in the human airways in chronic obstructive pulmonary disease.

    Science.gov (United States)

    Pettigrew, Melinda M; Ahearn, Christian P; Gent, Janneane F; Kong, Yong; Gallo, Mary C; Munro, James B; D'Mello, Adonis; Sethi, Sanjay; Tettelin, Hervé; Murphy, Timothy F

    2018-04-03

    Nontypeable Haemophilus influenzae (NTHi) exclusively colonize and infect humans and are critical to the pathogenesis of chronic obstructive pulmonary disease (COPD). In vitro and animal models do not accurately capture the complex environments encountered by NTHi during human infection. We conducted whole-genome sequencing of 269 longitudinally collected cleared and persistent NTHi from a 15-y prospective study of adults with COPD. Genome sequences were used to elucidate the phylogeny of NTHi isolates, identify genomic changes that occur with persistence in the human airways, and evaluate the effect of selective pressure on 12 candidate vaccine antigens. Strains persisted in individuals with COPD for as long as 1,422 d. Slipped-strand mispairing, mediated by changes in simple sequence repeats in multiple genes during persistence, regulates expression of critical virulence functions, including adherence, nutrient uptake, and modification of surface molecules, and is a major mechanism for survival in the hostile environment of the human airways. A subset of strains underwent a large 400-kb inversion during persistence. NTHi does not undergo significant gene gain or loss during persistence, in contrast to other persistent respiratory tract pathogens. Amino acid sequence changes occurred in 8 of 12 candidate vaccine antigens during persistence, an observation with important implications for vaccine development. These results indicate that NTHi alters its genome during persistence by regulation of critical virulence functions primarily by slipped-strand mispairing, advancing our understanding of how a bacterial pathogen that plays a critical role in COPD adapts to survival in the human respiratory tract.

  19. Can reanalysis datasets describe the persistent temperature and precipitation extremes over China?

    Science.gov (United States)

    Zhu, Jian; Huang, Dan-Qing; Yan, Pei-Wen; Huang, Ying; Kuang, Xue-Yuan

    2017-10-01

    The persistent temperature and precipitation extremes may bring damage to the economy and human due to their intensity, duration and areal coverage. Understanding the quality of reanalysis datasets in descripting these extreme events is important for detection, attribution and model evaluation. In this study, the performances of two reanalysis datasets [the twentieth century reanalysis (20CR) and Interim ECMWF reanalysis (ERA-Interim)] in reproducing the persistent temperature and precipitation extremes in China are evaluated. For the persistent temperature extremes, the two datasets can better capture the intensity indices than the frequency indices. The increasing/decreasing trend of persistent warm/cold extremes has been reasonably detected by the two datasets, particularly in the northern part of China. The ERA-Interim better reproduces the climatology and tendency of persistent warm extremes, while the 20CR has better skill to depict the persistent cold extremes. For the persistent precipitation extremes, the two datasets have the ability to reproduce the maximum consecutive 5-day precipitation. The two datasets largely underestimate the maximum consecutive dry days over the northern part of China, while overestimate the maximum consecutive wet days over the southern part of China. For the response of the precipitation extremes against the temperature variations, the ERA-Interim has good ability to depict the relationship among persistent precipitation extremes, local persistent temperature extremes, and global temperature variations over specific regions.

  20. Laboratory diagnosis of persistent human chlamydial infection

    Directory of Open Access Journals (Sweden)

    Mirja ePuolakkainen

    2013-12-01

    Full Text Available Diagnostic assays for persistent chlamydial infection are much needed to conduct high-quality, large-scale studies investigating the persistent state in vivo, its disease associations and the response to therapy. Yet in most studies the distinction between acute and persistent infection is based on the interpretation of the data obtained by the assays developed to diagnose acute infections or on complex assays available for research only and/or difficult to establish for clinical use. Novel biomarkers for detection of persistent chlamydial infection are urgently needed. Chlamydial whole genome proteome arrays are now available and they can identify chlamydial antigens that are differentially expressed between acute infection and persistent infection. Utilizing these data will lead to the development of novel diagnostic assays. Carefully selected specimens from well-studied patient populations are clearly needed in the process of translating the proteomic data into assays useful for clinical practice. Before such antigens are identified and validated assays become available, we face a challenge of deciding whether the persistent infection truly induced appearance of the proposed marker or do we just base our diagnosis of persistent infection on the presence of the suggested markers. Consequently, we must bear this in mind when interpreting the available data.

  1. Searches for lepton flavour violation at LHCb

    CERN Multimedia

    CERN. Geneva

    2013-01-01

    Charged lepton flavour is conserved within the Standard Model (SM) up to exceedingly small rates of about $10^{-50}$. This makes charged lepton flavour violation (cLFV) a very interesting place to look for hints of New Physics (NP). In fact, many NP scenarios predict cLFV to occur at rates within the reach of the experiments. Finding these transitions would mean a definite departure from the SM, while not finding them narrows the NP phase space. In this seminar, the latest LHCb results in the cLFV sector will be presented, and their implications for NP scenarios discussed.

  2. Stronger inducible defences enhance persistence of intraguild prey.

    Science.gov (United States)

    Kratina, Pavel; Hammill, Edd; Anholt, Bradley R

    2010-09-01

    1. Intraguild predation is widespread in nature despite its potentially destabilizing effect on food web dynamics. 2. Anti-predator inducible defences affect both birth and death rates of populations and have the potential to substantially modify food web dynamics and possibly increase persistence of intraguild prey. 3. In a chemostat experiment, we investigated the long-term effects of inducible defences on the dynamics of aquatic microbial food webs consisting of an intraguild predator, intraguild prey, and a basal resource. We controlled environmental conditions and selected strains of intraguild prey that varied in the strength of expressed inducible defences. 4. We found that intraguild prey with a stronger tendency to induce an anti-predator morphology persist for significantly longer periods of time. In addition, model selection analysis implied that flexibility in defensive phenotype (inducibility itself) is most likely the factor responsible for the enhanced persistence. 5. As patterns at the community level often emerge as a result of the life-history traits of individuals, we propose that inducible defences increase the persistence of populations and may contribute to the widespread occurrence of theoretically unstable intraguild predation systems in nature.

  3. Stable cellular senescence is associated with persistent DDR activation.

    Science.gov (United States)

    Fumagalli, Marzia; Rossiello, Francesca; Mondello, Chiara; d'Adda di Fagagna, Fabrizio

    2014-01-01

    The DNA damage response (DDR) is activated upon DNA damage generation to promote DNA repair and inhibit cell cycle progression in the presence of a lesion. Cellular senescence is a permanent cell cycle arrest characterized by persistent DDR activation. However, some reports suggest that DDR activation is a feature only of early cellular senescence that is then lost with time. This challenges the hypothesis that cellular senescence is caused by persistent DDR activation. To address this issue, we studied DDR activation dynamics in senescent cells. Here we show that normal human fibroblasts retain DDR markers months after replicative senescence establishment. Consistently, human fibroblasts from healthy aged donors display markers of DDR activation even three years in culture after entry into replicative cellular senescence. However, by extending our analyses to different human cell strains, we also observed an apparent DDR loss with time following entry into cellular senescence. This though correlates with the inability of these cell strains to survive in culture upon replicative or irradiation-induced cellular senescence. We propose a model to reconcile these results. Cell strains not suffering the prolonged in vitro culture stress retain robust DDR activation that persists for years, indicating that under physiological conditions persistent DDR is causally involved in senescence establishment and maintenance. However, cell strains unable to maintain cell viability in vitro, due to their inability to cope with prolonged cell culture-associated stress, show an only-apparent reduction in DDR foci which is in fact due to selective loss of the most damaged cells.

  4. Danish Mutual Fund Performance - Selectivity, Market Timing and Persistence

    DEFF Research Database (Denmark)

    Christensen, Michael

    Funds under management by Danish mutual funds have increased by 25% annually during the last 10 years and measured per capita Denmark has the third largest mutual fund industry in Europe. This paper provides the first independent performance analysis of Danish mutual funds. We analyse selectivity...... applying a single index model and a multi-factor model, respectively. Furthermore, we analyse the timing ability of the Danish mutual funds pursuing both the quadratic regressions of Treynor and Mazuy (1966) and the option approach suggested by Henriksson and Merton (1981). Finally, we analyse performance...... persistence using parametric as well as non-parametric methodologies. We conclude that in general Danish mutual funds perform neutrally, returns are non-persistent and Danish mutual funds have no timing ability....

  5. Treatment of persistent pain from torture

    DEFF Research Database (Denmark)

    Williams, Amanda C de C; Amris, Kirstine

    2017-01-01

    Torture and the conditions under which it is inflicted often leave persistent painful disorders. Because there may be no lasting signs, persistent pain is often misconceived as a somatic representation of psychological distress, also common after torture. This serious failure to understand...... the nature of persistent pain means that pain is largely overlooked and untreated in torture survivors. We carried out a systematic review on treatments for pain from torture, but found few studies and little use of current understanding and evidence. We discuss this in the context of treating pain...

  6. On the persistence of adiabatic shear bands

    Directory of Open Access Journals (Sweden)

    Bassim M.N.

    2012-08-01

    Full Text Available It is generally agreed that the initiation and development of adiabatic shear bands (ASBs are manifestations of damage in metallic materials subjected to high strain rates and large strains as those due to impact in a Hopkinson Bar system. Models for evolution of these bands have been described in the literature. One question that has not received attention is how persistent these bands are and whether their presence and effect can be reversed or eliminated by using a process of thermal (heat treatment or thermo-mechanical treatment that would relieve the material from the high strain associated with ASBs and their role as precursors to crack initiation and subsequent failure. Since ASBs are more prevalent and more defined in BCC metals including steels, a study was conducted to investigate the best conditions of generating ASBs in a heat treatable steel, followed by determining the best conditions for heat treatment of specimens already damaged by the presence of ASBs in order to relieve the strains due to ASBs and restore the material to an apparent microstructure without the “scars” due to the previous presence of ASBs. It was found that heat treatment achieves the curing from ASBs. This presentation documents the process undertaken to achieve this objective.

  7. Bacterial persistence is an active σS stress response to metabolic flux limitation.

    Science.gov (United States)

    Radzikowski, Jakub Leszek; Vedelaar, Silke; Siegel, David; Ortega, Álvaro Dario; Schmidt, Alexander; Heinemann, Matthias

    2016-09-21

    While persisters are a health threat due to their transient antibiotic tolerance, little is known about their phenotype and what actually causes persistence. Using a new method for persister generation and high-throughput methods, we comprehensively mapped the molecular phenotype of Escherichia coli during the entry and in the state of persistence in nutrient-rich conditions. The persister proteome is characterized by σ(S)-mediated stress response and a shift to catabolism, a proteome that starved cells tried to but could not reach due to absence of a carbon and energy source. Metabolism of persisters is geared toward energy production, with depleted metabolite pools. We developed and experimentally verified a model, in which persistence is established through a system-level feedback: Strong perturbations of metabolic homeostasis cause metabolic fluxes to collapse, prohibiting adjustments toward restoring homeostasis. This vicious cycle is stabilized and modulated by high ppGpp levels, toxin/anti-toxin systems, and the σ(S)-mediated stress response. Our system-level model consistently integrates past findings with our new data, thereby providing an important basis for future research on persisters. © 2016 The Authors. Published under the terms of the CC BY 4.0 license.

  8. Interbank funding as insurance mechanism for (persistent) liquidity shocks

    OpenAIRE

    Bluhm, Marcel

    2015-01-01

    The interbank market is important for the efficient functioning of the financial system, transmission of monetary policy and therefore ultimately the real economy. In particular, it facilitates banks' liquidity management. This paper aims at extending the literature which views interbank markets as mutual liquidity insurance mechanism by taking into account persistence of liquidity shocks. Following a theory of long-term interbank funding a financial system which is modeled as a micro-founded...

  9. An observable prerequisite for the existence of persistent currents

    OpenAIRE

    Szeftel, Jacob; Sandeau, Nicolas

    2017-01-01

    A classical model is presented for persistent currents in superconductors. Their existence is argued to be warranted because their decay would violate the second law of thermodynamics. This conclusion is achieved by analyzing comparatively Ohm's law and the Joule effect in normal metals and superconducting materials. Whereas Ohm's law applies in identical terms in both cases, the Joule effect is shown to cause the temperature of a superconducting sample to \\textit{decrease}. An experiment is ...

  10. Persistent Lagrangian transport patterns in the northwestern Gulf of Mexico

    OpenAIRE

    Gough, M. K.; Beron-Vera, F. J.; Olascoaga, M. J.; Sheinbaum, J.; Juoanno, J.; Duran, R.

    2017-01-01

    Persistent Lagrangian transport patterns at the ocean surface are revealed from Lagrangian Coherent Structures (LCSs) computed from daily climatological surface current velocities in the northwestern Gulf of Mexico (NWGoM). The velocities are produced by a submesoscale permitting regional ocean model of the Gulf of Mexico. The significance of the climatological LCSs (cLCSs) is supported with ensemble-mean drifter density evolutions from simulated and historical satellite-tracked drifter traje...

  11. [Persistent Perpetrator Contact in a Patient with Dissociative Identity Disorder].

    Science.gov (United States)

    Tschöke, Stefan; Eisele, Frank; Steinert, Tilman

    2016-05-01

    The case of a young woman with still ongoing incest and forced prostitution is presented. The criteria for a dissociative identity disorder (DID) were met. Due to persistent contact to the perpetrator she was repeatedly revictimized. Based on the model of trauma-related dissociation we discuss to what extent she was capable of self-determined decision making as well as therapeutic consequences resulting therefrom. © Georg Thieme Verlag KG Stuttgart · New York.

  12. Theoretical analysis on the probability of initiating persistent fission chain

    International Nuclear Information System (INIS)

    Liu Jianjun; Wang Zhe; Zhang Ben'ai

    2005-01-01

    For the finite multiplying system of fissile material in the presence of a weak neutron source, the authors analyses problems on the probability of initiating a persistent fission chain through reckoning the stochastic theory of neutron multiplication. In the theoretical treatment, the conventional point reactor conception model is developed to an improved form with position x and velocity v dependence. The estimated results including approximate value of the probability mentioned above and its distribution are given by means of diffusion approximation and compared with those with previous point reactor conception model. They are basically consistent, however the present model can provide details on the distribution. (authors)

  13. Active rejection of persistent disturbances in flexible space structures

    Science.gov (United States)

    Hwang, Cheng-Neng; Jayasuriya, Suhada; Parlos, Alexander G.; Sunkel, John W.

    1990-01-01

    A dynamic compensator for active rejection of persistent disturbances in flexible space structures is designed on the principle of the H(infinity)-optimization of the sensitivity transfer function matrix. A general state space solution is formulated to the multiinput multioutput H(infinity)-optimal control problem, allowing the use of the H(infinity)-optimal synthesis algorithm for the state-space models of space structures that result from model order reduction. Disturbances encountered in flexible space structures, such as shuttle docking, are investigated using the high-mode and the reduced-order models of a cantilevered two-bay truss, demonstrating the applicability of the H(infinity)-optimal approach.

  14. Fundamental bound on the persistence and capacity of short-term memory stored as graded persistent activity.

    Science.gov (United States)

    Koyluoglu, Onur Ozan; Pertzov, Yoni; Manohar, Sanjay; Husain, Masud; Fiete, Ila R

    2017-09-07

    It is widely believed that persistent neural activity underlies short-term memory. Yet, as we show, the degradation of information stored directly in such networks behaves differently from human short-term memory performance. We build a more general framework where memory is viewed as a problem of passing information through noisy channels whose degradation characteristics resemble those of persistent activity networks. If the brain first encoded the information appropriately before passing the information into such networks, the information can be stored substantially more faithfully. Within this framework, we derive a fundamental lower-bound on recall precision, which declines with storage duration and number of stored items. We show that human performance, though inconsistent with models involving direct (uncoded) storage in persistent activity networks, can be well-fit by the theoretical bound. This finding is consistent with the view that if the brain stores information in patterns of persistent activity, it might use codes that minimize the effects of noise, motivating the search for such codes in the brain.

  15. Evidence for a major gene influence on persistent developmental stuttering.

    Science.gov (United States)

    Viswanath, Nagalapura; Lee, Hee Suk; Chakraborty, Ranajit

    2004-06-01

    Stuttering is a complex developmental speech disorder of unknown etiology. There is a substantial aggregation of stuttering in families, suggesting a genetic component to the disorder. However, the exact mode of transmission is still unknown. An earlier study of 56 multigenerational pedigrees ascertained through single adult probands (38 males and 18 females) found that biological relatives of persistent developmental stutterers have an approximately 10-fold higher risk than in the general population; risk is higher for male relatives, and proband's sex does not affect recurrence and relative risks. In the present paper we conduct a complex segregation analysis of the same data, using the logistic regression model of the SAGE software. Based on the comparisons of model likelihoods, the Mendelian model was selected over all other nongenetic models and the general transmission model. This model was further refined into the most parsimonious model, which shows an autosomal dominant major gene effect influenced by two covariates: sex and affection status of parents. With this model applied to 47 informative multiplex pedigrees, a power calculation based on linkage simulation produced an average lod score of 6.8 for 10-cM density genome scan markers. These results give impetus for a genomewide linkage analysis of susceptibility to persistent developmental stuttering.

  16. Incorporating Persistent Pain in Phenotypic Frailty Measurement and Prediction of Adverse Health Outcomes.

    Science.gov (United States)

    Lohman, Matthew C; Whiteman, Karen L; Greenberg, Rebecca L; Bruce, Martha L

    2017-02-01

    Frailty, a syndrome of physiological deficits, is prevalent among older adults and predicts elevated risk of adverse health outcomes. Although persistent pain predicts similar risk, it is seldom considered in frailty measurement. This article evaluated the construct and predictive validity of including persistent pain in phenotypic frailty measurement. Frailty and persistent pain were operationalized using data from the Health and Retirement Study (2006-2012 waves). Among a subset of adults aged 65 and older (n = 3,652), we used latent class analysis to categorize frailty status and to evaluate construct validity. Using Cox proportional hazards models, we compared time to incident adverse outcomes (death, fall, hospitalization, institutionalization, and functional disability) between frailty classes determined by either including or excluding persistent pain as a frailty component. In latent class models, persistent pain occurred with other frailty components in patterns consistent with a medical syndrome. Frail and intermediately frail classes determined by including persistent pain were more strongly associated with all adverse outcomes compared with frail and intermediately frail classes determined excluding persistent pain. Frail respondents had significantly greater risk of death compared with nonfrail respondents when frailty models included rather than excluded persistent pain (respectively, hazard ratio [HR] = 3.87, 95% confidence interval [CI] = 2.99-5.00 (including pain); HR = 2.10, 95% CI = 1.71-2.59 (excluding pain). Findings support consideration of persistent pain as a component of the frailty phenotype. Persistent pain assessment may provide an expedient method to enhance frailty measurement and improve prediction of adverse outcomes. © The Author 2016. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  17. The persistent stereotype: children's images of scientists

    Science.gov (United States)

    Emens McAdam, Janice

    1990-03-01

    Through their reading children learn to regard scientists as eccentrics. It is shown that this stereotype has persisted for over thirty years and affects many adult attitudes. Some methods of breaking the author-reader cycle are suggested.

  18. Role of Prefrontal Persistent Activity in Working Memory

    Science.gov (United States)

    Riley, Mitchell R.; Constantinidis, Christos

    2016-01-01

    The prefrontal cortex is activated during working memory, as evidenced by fMRI results in human studies and neurophysiological recordings in animal models. Persistent activity during the delay period of working memory tasks, after the offset of stimuli that subjects are required to remember, has traditionally been thought of as the neural correlate of working memory. In the last few years several findings have cast doubt on the role of this activity. By some accounts, activity in other brain areas, such as the primary visual and posterior parietal cortex, is a better predictor of information maintained in visual working memory and working memory performance; dynamic patterns of activity may convey information without requiring persistent activity at all; and prefrontal neurons may be ill-suited to represent non-spatial information about the features and identity of remembered stimuli. Alternative interpretations about the role of the prefrontal cortex have thus been suggested, such as that it provides a top-down control of information represented in other brain areas, rather than maintaining a working memory trace itself. Here we review evidence for and against the role of prefrontal persistent activity, with a focus on visual neurophysiology. We show that persistent activity predicts behavioral parameters precisely in working memory tasks. We illustrate that prefrontal cortex represents features of stimuli other than their spatial location, and that this information is largely absent from early cortical areas during working memory. We examine memory models not dependent on persistent activity, and conclude that each of those models could mediate only a limited range of memory-dependent behaviors. We review activity decoded from brain areas other than the prefrontal cortex during working memory and demonstrate that these areas alone cannot mediate working memory maintenance, particularly in the presence of distractors. We finally discuss the discrepancy between

  19. Long - Memory Persistence in African Stock Markets

    Directory of Open Access Journals (Sweden)

    Emmanuel Numapau Gyamfi

    2016-05-01

    Full Text Available Emerging stock markets are said to become efficient with time. This study seeks to investigate this assertion by analyzing long - memory persistence in 8 African stock markets covering the period from 28 August 2000 to 28 August 2015. The Hurst exponent is used as our efficiency measure which is evaluated by the Detrended Fluctuation Analysis (DFA. Our findings show strong evidence of long - memory persistence in the markets studied therefore violating the weak - form Efficient Market Hypothesis (EMH.

  20. Persistence in PHP with the doctrine ORM

    CERN Document Server

    Dunglas, Kévin

    2013-01-01

    Persistence in PHP with the Doctrine ORM is a concise, fast, and focused guide to build a blog engine with advanced features such as native queries and lifecycle callbacks.This book is primarily intended for PHP developers and architects who want to increase their skills in the field of Persistence and ORM to map the data they are working on to objects they are using in programming. Basic knowledge of databases and PDO and working knowledge of PHP namespaces is a prerequisite.

  1. [Therapeutic approach in persistent diabetic macular edema].

    Science.gov (United States)

    Brănişteanu, Daniel; Moraru, Andreea

    2014-01-01

    Terminology of persistent diabetic macular edema has been initially reserved to cases unresponsive to conventional laser photocoagulation according to ETDRS criteria. While knowledge about pathophysiology of macular edema evolved and new drugs became available, the terminology of persistent diabetic macular edema expanded to include resistance to most current therapies. The purpose of this paper is to review medical and surgical options in the treatment of such difficult cases according to literature data and personal experience.

  2. Persistent homology and non-Gaussianity

    Science.gov (United States)

    Cole, Alex; Shiu, Gary

    2018-03-01

    In this paper, we introduce the topological persistence diagram as a statistic for Cosmic Microwave Background (CMB) temperature anisotropy maps. A central concept in 'Topological Data Analysis' (TDA), the idea of persistence is to represent a data set by a family of topological spaces. One then examines how long topological features 'persist' as the family of spaces is traversed. We compute persistence diagrams for simulated CMB temperature anisotropy maps featuring various levels of primordial non-Gaussianity of local type. Postponing the analysis of observational effects, we show that persistence diagrams are more sensitive to local non-Gaussianity than previous topological statistics including the genus and Betti number curves, and can constrain Δ fNLloc= 35.8 at the 68% confidence level on the simulation set, compared to Δ fNLloc= 60.6 for the Betti number curves. Given the resolution of our simulations, we expect applying persistence diagrams to observational data will give constraints competitive with those of the Minkowski Functionals. This is the first in a series of papers where we plan to apply TDA to different shapes of non-Gaussianity in the CMB and Large Scale Structure.

  3. Considerations of persistence and security in CHOICES, an object-oriented operating system

    Science.gov (United States)

    Campbell, Roy H.; Madany, Peter W.

    1990-01-01

    The current design of the CHOICES persistent object implementation is summarized, and research in progress is outlined. CHOICES is implemented as an object-oriented system, and persistent objects appear to simplify and unify many functions of the system. It is demonstrated that persistent data can be accessed through an object-oriented file system model as efficiently as by an existing optimized commercial file system. The object-oriented file system can be specialized to provide an object store for persistent objects. The problems that arise in building an efficient persistent object scheme in a 32-bit virtual address space that only uses paging are described. Despite its limitations, the solution presented allows quite large numbers of objects to be active simultaneously, and permits sharing and efficient method calls.

  4. Treatment persistence in patients with rheumatoid arthritis and ankylosing spondylitis.

    Science.gov (United States)

    Machado, Marina Amaral de Ávila; Moura, Cristiano Soares de; Ferré, Felipe; Bernatsky, Sasha; Rahme, Elham; Acurcio, Francisco de Assis

    2016-08-22

    To evaluate treatment persistence in patients with rheumatoid arthritis and ankylosing spondylitis who started therapies with disease-modifying antirheumatic drugs (DMARD) and tumor necrosis factor blockers (anti-TNF drugs). This retrospective cohort study from July 2008 to September 2013 evaluated therapy persistence, which is defined as the period between the start of treatment until it is discontinued, allowing for an interval of up to 30 days between the prescription end and the start of the next prescription. Odds ratio (OR) with 95% confidence intervals (95%CI) were calculated by logistic regression models to estimate the patients' chances of persisting in their therapies after the first and after the two first years of follow-up. The study included 11,642 patients with rheumatoid arthritis - 2,241 of these started on anti-TNF drugs (+/-DMARD) and 9,401 patients started on DMARD - and 1,251 patients with ankylosing spondylitis - 976 of them were started on anti-TNF drugs (+/-DMARD) and 275 were started on DMARD. In the first year of follow-up, 63.5% of the patients persisted in their therapies with anti-TNF drugs (+/-DMARD) and 54.1% remained using DMARD in the group with rheumatoid arthritis. In regards to ankylosing spondylitis, 79.0% of the subjects in anti-TNF (+/-DMARD) group and 41.1% of the subjects in the DMARD group persisted with their treatments. The OR (95%CI) for therapy persistence was 1.50 (1.34-1.67) for the anti-TNF (+/-DMARD) group as compared with the DMARD group in the first year for the patients with rheumatoid arthritis, and 2.33 (1.74-3.11) for the patients with ankylosing spondylitis. A similar trend was observed at the end of the second year. A general trend of higher rates of therapy persistence with anti-TNF drugs (+/-DMARD) was observed as compared to DMARD in the study period. We observed higher persistence rates for anti-TNF drugs (+/-DMARD) in patients with ankylosing spondylitis as compared to rheumatoid arthritis; and a higher

  5. Salt stress-induced transcription of σB- and CtsR-regulated genes in persistent and non-persistent Listeria monocytogenes strains from food processing plants.

    Science.gov (United States)

    Ringus, Daina L; Ivy, Reid A; Wiedmann, Martin; Boor, Kathryn J

    2012-03-01

    Listeria monocytogenes is a foodborne pathogen that can persist in food processing environments. Six persistent and six non-persistent strains from fish processing plants and one persistent strain from a meat plant were selected to determine if expression of genes in the regulons of two stress response regulators, σ(B) and CtsR, under salt stress conditions is associated with the ability of L. monocytogenes to persist in food processing environments. Subtype data were also used to categorize the strains into genetic lineages I or II. Quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR) was used to measure transcript levels for two σ(B)-regulated genes, inlA and gadD3, and two CtsR-regulated genes, lmo1138 and clpB, before and after (t=10 min) salt shock (i.e., exposure of exponential phase cells to BHI+6% NaCl for 10 min at 37°C). Exposure to salt stress induced higher transcript levels relative to levels under non-stress conditions for all four stress and virulence genes across all wildtype strains tested. Analysis of variance (ANOVA) of induction data revealed that transcript levels for one gene (clpB) were induced at significantly higher levels in non-persistent strains compared to persistent strains (p=0.020; two-way ANOVA). Significantly higher transcript levels of gadD3 (p=0.024; two-way ANOVA) and clpB (p=0.053; two-way ANOVA) were observed after salt shock in lineage I strains compared to lineage II strains. No clear association between stress gene transcript levels and persistence was detected. Our data are consistent with an emerging model that proposes that establishment of L. monocytogenes persistence in a specific environment occurs as a random, stochastic event, rather than as a consequence of specific bacterial strain characteristics.

  6. Herbicide Persistence in Seawater Simulation Experiments.

    Directory of Open Access Journals (Sweden)

    Philip Mercurio

    Full Text Available Herbicides are detected year-round in marine waters, including those of the World Heritage listed Great Barrier Reef (GBR. The few previous studies that have investigated herbicide persistence in seawater generally reported half-lives in the order of months, and several studies were too short to detect significant degradation. Here we investigated the persistence of eight herbicides commonly detected in the GBR or its catchments in standard OECD simulation flask experiments, but with the aim to mimic natural conditions similar to those found on the GBR (i.e., relatively low herbicide concentrations, typical temperatures, light and microbial communities. Very little degradation was recorded over the standard 60 d period (Experiment 1 so a second experiment was extended to 365 d. Half-lives of PSII herbicides ametryn, atrazine, diuron, hexazinone and tebuthiuron were consistently greater than a year, indicating high persistence. The detection of atrazine and diuron metabolites and longer persistence in mercuric chloride-treated seawater confirmed that biodegradation contributed to the breakdown of herbicides. The shortest half-life recorded was 88 d for growth-regulating herbicide 2,4-D at 31°C in the dark, while the fatty acid-inhibitor metolachlor exhibited a minimum half-life of 281 d. The presence of moderate light and elevated temperatures affected the persistence of most of the herbicides; however, the scale and direction of the differences were not predictable and were likely due to changes in microbial community composition. The persistence estimates here represent some of the first appropriate data for application in risk assessments for herbicide exposure in tropical marine systems. The long persistence of herbicides identified in the present study helps explain detection of herbicides in nearshore waters of the GBR year round. Little degradation of these herbicides would be expected during the wet season with runoff and associated

  7. Herbicide Persistence in Seawater Simulation Experiments

    Science.gov (United States)

    Mercurio, Philip; Mueller, Jochen F.; Eaglesham, Geoff; Flores, Florita; Negri, Andrew P.

    2015-01-01

    Herbicides are detected year-round in marine waters, including those of the World Heritage listed Great Barrier Reef (GBR). The few previous studies that have investigated herbicide persistence in seawater generally reported half-lives in the order of months, and several studies were too short to detect significant degradation. Here we investigated the persistence of eight herbicides commonly detected in the GBR or its catchments in standard OECD simulation flask experiments, but with the aim to mimic natural conditions similar to those found on the GBR (i.e., relatively low herbicide concentrations, typical temperatures, light and microbial communities). Very little degradation was recorded over the standard 60 d period (Experiment 1) so a second experiment was extended to 365 d. Half-lives of PSII herbicides ametryn, atrazine, diuron, hexazinone and tebuthiuron were consistently greater than a year, indicating high persistence. The detection of atrazine and diuron metabolites and longer persistence in mercuric chloride-treated seawater confirmed that biodegradation contributed to the breakdown of herbicides. The shortest half-life recorded was 88 d for growth-regulating herbicide 2,4-D at 31°C in the dark, while the fatty acid-inhibitor metolachlor exhibited a minimum half-life of 281 d. The presence of moderate light and elevated temperatures affected the persistence of most of the herbicides; however, the scale and direction of the differences were not predictable and were likely due to changes in microbial community composition. The persistence estimates here represent some of the first appropriate data for application in risk assessments for herbicide exposure in tropical marine systems. The long persistence of herbicides identified in the present study helps explain detection of herbicides in nearshore waters of the GBR year round. Little degradation of these herbicides would be expected during the wet season with runoff and associated flood plumes

  8. Persistent Authentication in Smart Environments

    DEFF Research Database (Denmark)

    Hansen, Mads Syska; Kirschmeyer, Martin; Jensen, Christian D.

    2008-01-01

    Inhabitants in smart environments are often authenticated when they enter the smart environment, e.g., through biometrics or smart-/swipe-card systems. It may sometimes be necessary to re-authenticate when an inhabitant wishes to enter a restricted area or access ambient services or location based...... information, e.g., it is common to have swipe card terminals placed next to doors to restricted areas. This means that all access to protected resources must have individual means of authenticating users, which makes the access control system more expensive and less flexible, because access controls...... will not be installed unless it is absolutely necessary. The cost of installing and maintaining an authentication infrastructure and the inconvenience of repeatedly authenticating toward different location based service providers mean that new models of authentication are needed in smart environments. This paper...

  9. Host factors influencing viral persistence

    DEFF Research Database (Denmark)

    Thomsen, Allan Randrup; Nansen, A; Ørding Andreasen, Susanne

    2000-01-01

    With the aim of characterizing the antiviral immune response to a non-cytocidal virus, we studied the outcome of lymphocytic choriomeningitis virus infection in a number of gene knockout mouse strains. Two virus strains differing markedly in their capacity to spread and replicate inside the murine....... Reappearance of virus is associated with impaired long-term CD8+ T-cell mediated immune surveillance, and the time to virus resurgence is inversely correlated to the replication rate of the virus. Our studies also reveal that interferon-gamma is a central cytokine, and depending on the rate of virus...... replication, mice lacking the ability to produce interferon-gamma may develop either a severe, mostly fatal, T-cell mediated wasting syndrome or a chronic infection characterized by long-term coexistence of antiviral cytotoxic T lymphocytes and infectious virus. Mathematical modelling indicates...

  10. Persistent topology for cryo-EM data analysis.

    Science.gov (United States)

    Xia, Kelin; Wei, Guo-Wei

    2015-08-01

    In this work, we introduce persistent homology for the analysis of cryo-electron microscopy (cryo-EM) density maps. We identify the topological fingerprint or topological signature of noise, which is widespread in cryo-EM data. For low signal-to-noise ratio (SNR) volumetric data, intrinsic topological features of biomolecular structures are indistinguishable from noise. To remove noise, we employ geometric flows that are found to preserve the intrinsic topological fingerprints of cryo-EM structures and diminish the topological signature of noise. In particular, persistent homology enables us to visualize the gradual separation of the topological fingerprints of cryo-EM structures from those of noise during the denoising process, which gives rise to a practical procedure for prescribing a noise threshold to extract cryo-EM structure information from noise contaminated data after certain iterations of the geometric flow equation. To further demonstrate the utility of persistent homology for cryo-EM data analysis, we consider a microtubule intermediate structure Electron Microscopy Data (EMD 1129). Three helix models, an alpha-tubulin monomer model, an alpha-tubulin and beta-tubulin model, and an alpha-tubulin and beta-tubulin dimer model, are constructed to fit the cryo-EM data. The least square fitting leads to similarly high correlation coefficients, which indicates that structure determination via optimization is an ill-posed inverse problem. However, these models have dramatically different topological fingerprints. Especially, linkages or connectivities that discriminate one model from another, play little role in the traditional density fitting or optimization but are very sensitive and crucial to topological fingerprints. The intrinsic topological features of the microtubule data are identified after topological denoising. By a comparison of the topological fingerprints of the original data and those of three models, we found that the third model is

  11. Persistent pulmonary hypertension of the newborn

    Directory of Open Access Journals (Sweden)

    Ru-Jeng Teng

    2013-04-01

    Full Text Available Persistent pulmonary hypertension of the newborn (PPHN is a severe pulmonary disorder which occurs at a rate of one in every 500 live births. About 10–50% of the victims will die of the problem and 7–20% of the survivors develop long-term impairments such as hearing deficit, chronic lung disease, and intracranial bleed. Most adult survivors show evidence of augmented pulmonary vasoreactivity, suggesting a phenotypical change. Several animal models have been used to study the pathophysiology and help to develop new therapeutic modality for PPHN. The etiology of PPHN can be classified into three groups: (1 abnormally constricted pulmonary vasculature as a result of parenchymal diseases; (2 hypoplastic pulmonary vasculature; and (3 normal parenchyma with remodeled pulmonary vasculature. Impaired vasorelaxation of pulmonary artery and reduced blood vessel density in lungs are two characteristic findings in PPHN. Medical treatment includes sedation, oxygen, mechanical ventilation, vasorelaxants (inhaled nitric oxide, inhaled or intravenous prostacyclin, intravenous prostaglandin E1, magnesium sulfate, and inotropic agents. Phosphodiesterase inhibitors have recently been studied as another therapeutic agent for PPHN. Endothelin-1 (ET-1 inhibitors have been studied in animals and a case of premature infant with PPHN successfully treated with an ET-I inhibitor has been reported in the literature. Surfactants have been reported as an adjunct treatment for PPHN as a complication of meconium aspiration syndrome. Even with the introduction of several new therapeutic modalities there has been no significant change in survival rate. Extracorporeal membrane oxygenator is used when medical treatment fails and the patient is considered to have a recoverable cause of PPHN.

  12. Estimativas de parâmetros genéticos para produção de leite e persistência da lactação em vacas Gir, aplicando modelos de regressão aleatória Estimates of genetic parameters for milk yield and persistency of lactation of Gyr cows, applying random regression models

    Directory of Open Access Journals (Sweden)

    Luis Gabriel González Herrera

    2008-09-01

    of Gyr cows calving between 1990 and 2005 were used to estimate genetic parameters of monthly test-day milk yield (TDMY. Records were analyzed by random regression models (MRA that included the additive genetic and permanent environmental random effects and the contemporary group, age of cow at calving (linear and quadratic components and the average trend of the population as fixed effects. Random trajectories were fitted by Wilmink's (WIL and Ali & Schaeffer's (AS parametric functions. Residual variances were fitted by step functions with 1, 4, 6 or 10 classes. The contemporary group was defined by herd-year-season of test-day and included at least three animals. Models were compared by Akaike's and Schwarz's Bayesian (BIC information criterion. The AS function used for modeling the additive genetic and permanent environmental effects with heterogeneous residual variances adjusted with a step function with four classes was the best fitted model. Heritability estimates ranged from 0.21 to 0.33 for the AS function and from 0.17 to 0.30 for WIL function and were larger in the first half of the lactation period. Genetic correlations between TDMY were high and positive for adjacent test-days and decreased as days between records increased. Predicted breeding values for total 305-day milk yield (MRA305 and specific periods of lactation (obtained by the mean of all breeding values in the periods using the AS function were compared with that predicted by a standard model using accumulated 305-day milk yield (PTA305 by rank correlation. The magnitude of correlations suggested differences may be observed in ranking animals by using the different criteria which were compared in this study.

  13. Persistent Dentoalveolar Pain Disorder: A Comprehensive Review.

    Science.gov (United States)

    Malacarne, Alberto; Spierings, Egilius L H; Lu, Chao; Maloney, George E

    2018-02-01

    Persistent dentoalveolar pain of idiopathic origin represents a diagnostic challenge for the dentist and physician alike. Disagreement on taxonomy and diagnostic criteria presents a significant limit to the advancement of research in the field. Patients struggle with a lack of knowledge by dental and medical professionals, diagnostic delays, and unnecessary treatments. A PubMed search was performed as of January 1, 2017 by using the terms atypical odontalgia, phantom tooth pain, persistent idiopathic facial pain, painful posttraumatic trigeminal neuropathy, idiopathic toothache, persistent dentoalveolar pain disorder, nonodontogenic tooth pain, and continuous neuropathic orofacial pain. Three hundred forty-five abstracts were screened, and 128 articles that were pertinent to the topic went through full-text reading. Case reports and narrative reviews constitute the majority of available literature. Several retrospective case-control studies investigated the clinical characteristics, pathophysiology, and diagnostic processes. Treatment strategies were evaluated in only 7 open-label and 2 randomized controlled trials. Persistent dentoalveolar pain disorder is likely neuropathic in origin, but pathophysiological mechanisms to explain the onset and persistence of the pain are still far from understood. A correct diagnosis should be established before treatments are performed. Researchers should reach an agreement on the diagnostic criteria to enable a coherent research path to better understand the condition and reduce patient suffering. Copyright © 2017 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  14. The role of myelin in Theiler's virus persistence in the central nervous system.

    Directory of Open Access Journals (Sweden)

    Jean-Pierre Roussarie

    2007-02-01

    Full Text Available Theiler's virus, a picornavirus, persists for life in the central nervous system of mouse and causes a demyelinating disease that is a model for multiple sclerosis. The virus infects neurons first but persists in white matter glial cells, mainly oligodendrocytes and macrophages. The mechanism, by which the virus traffics from neurons to glial cells, and the respective roles of oligodendrocytes and macrophages in persistence are poorly understood. We took advantage of our previous finding that the shiverer mouse, a mutant with a deletion in the myelin basic protein gene (Mbp, is resistant to persistent infection to examine the role of myelin in persistence. Using immune chimeras, we show that resistance is not mediated by immune responses or by an efficient recruitment of inflammatory cells into the central nervous system. With both in vivo and in vitro experiments, we show that the mutation does not impair the permissiveness of neurons, oligodendrocytes, and macrophages to the virus. We demonstrate that viral antigens are present in cytoplasmic channels of myelin during persistent infection of wild-type mice. Using the optic nerve as a model, we show that the virus traffics from the axons of retinal ganglion cells to the cytoplasmic channels of myelin, and that this traffic is impaired by the shiverer mutation. These results uncover an unsuspected axon to myelin traffic of Theiler's virus and the essential role played by the infection of myelin/oligodendrocyte in persistence.

  15. Defending Against Advanced Persistent Threats Using Game-Theory.

    Science.gov (United States)

    Rass, Stefan; König, Sandra; Schauer, Stefan

    2017-01-01

    Advanced persistent threats (APT) combine a variety of different attack forms ranging from social engineering to technical exploits. The diversity and usual stealthiness of APT turns them into a central problem of contemporary practical system security, since information on attacks, the current system status or the attacker's incentives is often vague, uncertain and in many cases even unavailable. Game theory is a natural approach to model the conflict between the attacker and the defender, and this work investigates a generalized class of matrix games as a risk mitigation tool for an advanced persistent threat (APT) defense. Unlike standard game and decision theory, our model is tailored to capture and handle the full uncertainty that is immanent to APTs, such as disagreement among qualitative expert risk assessments, unknown adversarial incentives and uncertainty about the current system state (in terms of how deeply the attacker may have penetrated into the system's protective shells already). Practically, game-theoretic APT models can be derived straightforwardly from topological vulnerability analysis, together with risk assessments as they are done in common risk management standards like the ISO 31000 family. Theoretically, these models come with different properties than classical game theoretic models, whose technical solution presented in this work may be of independent interest.

  16. Psychopharmacology of Persistent Violence and Aggression.

    Science.gov (United States)

    Meyer, Jonathan M; Cummings, Michael A; Proctor, George; Stahl, Stephen M

    2016-12-01

    Persistent violence not due to acute psychosis or mania can be managed only after appropriate characterization of the aggressive episodes (psychotic, impulsive, or predatory/planned/instrumental). The type of violence combined with the psychiatric diagnosis dictates the evidence-based pharmacologic approaches for psychotically motivated and impulsive aggression, whereas instrumental violence mandates forensic/behavioral strategies. For nonacute inpatients, schizophrenia spectrum disorders, traumatic brain injury, and dementia comprise the majority of individuals who are persistently aggressive, with impulsive actions the most common form of violence across all diagnoses. Neurobiological considerations combined with empirical data provide a comprehensive framework for systematic medication trials to manage persistently aggressive patients. Copyright © 2016 Elsevier Inc. All rights reserved.

  17. The Economy of Persistence: Mario the Tailor

    Directory of Open Access Journals (Sweden)

    Prudence Black

    2016-03-01

    Full Text Available Mario Conte has had a tailor shop in King Street, Newtown since the mid 1960s. Taking an interview with Mario as its point of departure, this article describes the persistence of a skilled worker whose practices and techniques remain the same in a world that has long changed. While inattentive to what rules might be used to decorate a shop window, Mario continues to make and sew in the way that he learnt in post-war Italy. Mario’s persistence could be described as all the skills and other elements that need to be in place to keep him working, in particular the tradition of tailoring techniques he has remained true to over the last fifty years. The hand stitching of his tailoring is like a metronome of that persistence.

  18. International perspectives on retention and persistence

    Directory of Open Access Journals (Sweden)

    Gary Burkholder

    2014-06-01

    Full Text Available Access to higher education globally is increasing dramatically; attainment of tertiary degrees is a high priority, as educational attainment is associated with increased personal incomes as well as growth of the middle class in developing countries. The purpose of this essay is to briefly examine retention and persistence issues from a global perspective, review some retention strategies that have been employed at schools outside the United States, and to identify several key factors that related to retention and persistence globally, including access, infrastructure, financial consideration, and readiness for tertiary education.  There exists an opportunity to utilize knowledge gained in the evolution of the higher education system in the United States to help address the problems associated with retention and persistence.   DOI: 10.18870/hlrc.v4i2.208

  19. Understanding mild persistent asthma in children

    DEFF Research Database (Denmark)

    Bisgaard, Hans; Szefler, Stanley J

    2005-01-01

    Limitations in asthma prevalence studies and difficulties in diagnosing pediatric asthma lead to uncertainty over the full extent of mild persistent asthma in children and adolescents. Although recent surveys have reported that the majority of pediatric patients with asthma in the United States...... and Europe have symptoms consistent with mild disease, these surveys have limitations in design. Thus, the true prevalence of mild asthma remains unknown. It is unclear whether children with mild persistent asthma progress to more severe asthma, but the risk of severe asthma exacerbations seems...... to be unrelated to the symptom severity. Clinical studies restricted to pediatric patients with mild asthma are limited, but available data do suggest substantial morbidity of mild persistent asthma in this population and support inhaled corticosteroid intervention. There is a need for further investigation...

  20. Persistent toxic substances: sources, fates and effects.

    Science.gov (United States)

    Wong, Ming H; Armour, Margaret-Ann; Naidu, Ravi; Man, Ming

    2012-01-01

    Persistent toxic substances (PTS) include the Stockholm persistent organic pollutants, like dichlorodiphenyltrichloroethane, polychlorinated biphenyls, dioxin/furan, etc., and organometallic compounds, like organomercury, organotin, and organolead, which all share the same characteristics of being persistent, toxic, bioaccumulative, and able to travel long distances through different media. The adverse health effects of some of the emerging chemicals like pentabromodiphenyl ether, bisphenol A, and di(2-ethylhexyl)phthalate, which are widely used in daily appliances (e.g., TVs, computers, mobile phones, plastic baby bottles), have become a public health concern due to more evidence now available showing their adverse effects like disturbance of the endocrine system and cancer. This article is an attempt to review the current status of PTS in our environment, citing case studies in China and North America, and whether our existing drinking water treatment and wastewater treatment processes are adequate in removing them from water. Some management issues of these emerging chemicals of concern are also discussed.

  1. Persistent Pain and Sensory Abnormalities after Abdominoplasty

    DEFF Research Database (Denmark)

    Presman, Benjamin; Finnerup, Kenneth; Andresen, Sven R

    2015-01-01

    and characteristics of persistent pain after abdominoplasty, which is one of the most frequent cosmetic surgical procedures. METHODS: In September 2014, a link to a web-based questionnaire was mailed to 217 patients who had undergone abdominoplasty between 2006 and 2014 at the Department of Plastic Surgery, Aalborg......BACKGROUND: Persistent postsurgical pain is a well-recognized problem after a number of common surgical procedures, such as amputation, thoracotomy, and inguinal hernia repair. Less is known about persistent pain after cosmetic surgical procedures. We, therefore, decided to study the incidence...... University Hospital, Denmark. The questionnaire included questions about pain and sensory abnormalities located to the abdominal skin, and physical and psychological function; patient satisfaction with surgery was rated on a 4-point scale. RESULTS: One hundred seventy patients answered the questionnaire...

  2. How to decode Unemployment Persistence: An econometric framework for identifying and comparing the sources of persistence

    DEFF Research Database (Denmark)

    Møller, Niels Framroze

    2016-01-01

    Most econometric analyses of persistence focus on the existence of non-stationary unemployment but not the origin of this. The present research contains a multivariate econometric framework for identifying and comparing different sources of unemployment persistence (e.g. hysteresis versus a slowly...

  3. Amnestically Induced Persistence in Random Walks

    Science.gov (United States)

    Cressoni, J. C.; da Silva, Marco Antonio Alves; Viswanathan, G. M.

    2007-02-01

    We study how the Hurst exponent α depends on the fraction f of the total time t remembered by non-Markovian random walkers that recall only the distant past. We find that otherwise nonpersistent random walkers switch to persistent behavior when inflicted with significant memory loss. Such memory losses induce the probability density function of the walker’s position to undergo a transition from Gaussian to non-Gaussian. We interpret these findings of persistence in terms of a breakdown of self-regulation mechanisms and discuss their possible relevance to some of the burdensome behavioral and psychological symptoms of Alzheimer’s disease and other dementias.

  4. Persistence and drug tolerance in pathogenic yeast

    DEFF Research Database (Denmark)

    Bojsen, Rasmus Kenneth; Regenberg, Birgitte; Folkesson, Sven Anders

    2017-01-01

    leading to drug recalcitrance is the formation of antifungal persister cells. These cells have wild-type genotype with the ability to survive exposure to antifungal agents due to changed membrane composition, upregulated stress response, and enhanced cell wall integrity. Knowledge of the mechanisms...... are quiescent in G0 of the cell cycle. This knowledge leads us to suggest that the identified shared drug-tolerance mechanisms of persister and quiescent cells may serve as a foundation for developing novel treatment strategies that are independent of growth mode against systemic fungal infections....

  5. Persisting nutritional neuropathy amongst former war prisoners.

    Science.gov (United States)

    Gill, G V; Bell, D R

    1982-01-01

    Of 898 former Far East prisoners of war, assessed between 1968 and 1981, 49 (5.5%) had evidence of persisting symptomatic neurological disease dating back to their periods of malnutrition in captivity. The commonest syndromes were peripheral neuropathy (often of "burning foot" type), optic atrophy, and sensori-neural deafness. Though nutritional neuropathies disappeared soon after release in most ex-Far East prisoners of war, in some they have persisted up to 36 years since exposure to the nutritional insult. PMID:6292369

  6. Persistence and stability for the three species ratio-dependent food ...

    African Journals Online (AJOL)

    Persistence and stability for the three species ratio-dependent food–chain model. M Agarwal, V Singh. Abstract. In this paper, we have proposed and analyzed a tritrophic food chain model composed of a prey, a middle predator and a top predator. Ratio-dependent functional response is considered to model the interactions ...

  7. Human mobility networks and persistence of rapidly mutating pathogens.

    Science.gov (United States)

    Aleta, Alberto; Hisi, Andreia N S; Meloni, Sandro; Poletto, Chiara; Colizza, Vittoria; Moreno, Yamir

    2017-03-01

    Rapidly mutating pathogens may be able to persist in the population and reach an endemic equilibrium by escaping hosts' acquired immunity. For such diseases, multiple biological, environmental and population-level mechanisms determine the dynamics of the outbreak, including pathogen's epidemiological traits (e.g. transmissibility, infectious period and duration of immunity), seasonality, interaction with other circulating strains and hosts' mixing and spatial fragmentation. Here, we study a susceptible-infected-recovered-susceptible model on a metapopulation where individuals are distributed in sub-populations connected via a network of mobility flows. Through extensive numerical simulations, we explore the phase space of pathogen's persistence and map the dynamical regimes of the pathogen following emergence. Our results show that spatial fragmentation and mobility play a key role in the persistence of the disease whose maximum is reached at intermediate mobility values. We describe the occurrence of different phenomena including local extinction and emergence of epidemic waves, and assess the conditions for large-scale spreading. Findings are highlighted in reference to previous studies and to real scenarios. Our work uncovers the crucial role of hosts' mobility on the ecological dynamics of rapidly mutating pathogens, opening the path for further studies on disease ecology in the presence of a complex and heterogeneous environment.

  8. Electrostatic stiffening and induced persistence length for coassembled molecular bottlebrushes

    Science.gov (United States)

    Storm, Ingeborg M.; Stuart, Martien A. Cohen; de Vries, Renko; Leermakers, Frans A. M.

    2018-03-01

    A self-consistent field analysis for tunable contributions to the persistence length of isolated semiflexible polymer chains including electrostatically driven coassembled deoxyribonucleic acid (DNA) bottlebrushes is presented. When a chain is charged, i.e., for polyelectrolytes, there is, in addition to an intrinsic rigidity, an electrostatic stiffening effect, because the electric double layer resists bending. For molecular bottlebrushes, there is an induced contribution due to the grafts. We explore cases beyond the classical phantom main-chain approximation and elaborate molecularly more realistic models where the backbone has a finite volume, which is necessary for treating coassembled bottlebrushes. We find that the way in which the linear charge density or the grafting density is regulated is important. Typically, the stiffening effect is reduced when there is freedom for these quantities to adapt to the curvature stresses. Electrostatically driven coassembled bottlebrushes, however, are relatively stiff because the chains have a low tendency to escape from the compressed regions and the electrostatic binding force is largest in the convex part. For coassembled bottlebrushes, the induced persistence length is a nonmonotonic function of the polymer concentration: For low polymer concentrations, the stiffening grows quadratically with coverage; for semidilute polymer concentrations, the brush chains retract and regain their Gaussian size. When doing so, they lose their induced persistence length contribution. Our results correlate well with observed physical characteristics of electrostatically driven coassembled DNA-bioengineered protein-polymer bottlebrushes.

  9. Persistent Luminescence in Eu2+-Doped Compounds: A Review

    Directory of Open Access Journals (Sweden)

    Koen Van den Eeckhout

    2010-04-01

    Full Text Available In 1996, Matsuzawa et al. reported on the extremely long-lasting afterglow of SrAl2O4:Eu2+ codoped with Dy3+ ions, which was more than 10-times brighter than the previously widely used ZnS:Cu,Co. Since then, research for stable and efficient persistent phosphors has continuously gained popularity. However, even today - almost 15 years after the discovery of SrAl2O4:Eu2+, Dy3+ - the number of persistent luminescent materials is still relatively low. Furthermore, the mechanism behind this phenomenon is still unclear. Although most authors agree on the general features, such as the existence of long-lived trap levels, many details are still shrouded in mystery. In this review, we present an overview of the important classes of known persistent luminescent materials based on Eu2+-emission and how they were prepared, and we take a closer look at the models and mechanisms that have been suggested to explain bright afterglow in various compounds.

  10. Persistent Luminescence in Eu2+-Doped Compounds: A Review

    Science.gov (United States)

    Van den Eeckhout, Koen; Smet, Philippe F.; Poelman, Dirk

    2010-01-01

    In 1996, Matsuzawa et al. reported on the extremely long-lasting afterglow of SrAl2O4:Eu2+ codoped with Dy3+ ions, which was more than 10-times brighter than the previously widely used ZnS:Cu,Co. Since then, research for stable and efficient persistent phosphors has continuously gained popularity. However, even today - almost 15 years after the discovery of SrAl2O4:Eu2+, Dy3+ - the number of persistent luminescent materials is still relatively low. Furthermore, the mechanism behind this phenomenon is still unclear. Although most authors agree on the general features, such as the existence of long-lived trap levels, many details are still shrouded in mystery. In this review, we present an overview of the important classes of known persistent luminescent materials based on Eu2+-emission and how they were prepared, and we take a closer look at the models and mechanisms that have been suggested to explain bright afterglow in various compounds.

  11. Improving Underrepresented Minority Student Persistence in STEM

    Science.gov (United States)

    Estrada, Mica; Burnett, Myra; Campbell, Andrew G.; Campbell, Patricia B.; Denetclaw, Wilfred F.; Gutiérrez, Carlos G.; Hurtado, Sylvia; John, Gilbert H.; Matsui, John; McGee, Richard; Okpodu, Camellia Moses; Robinson, T. Joan; Summers, Michael F.; Werner-Washburne, Maggie; Zavala, MariaElena

    2016-01-01

    Members of the Joint Working Group on Improving Underrepresented Minorities (URMs) Persistence in Science, Technology, Engineering, and Mathematics (STEM)--convened by the National Institute of General Medical Sciences and the Howard Hughes Medical Institute--review current data and propose deliberation about why the academic "pathways"…

  12. Retrospective review of neonates with persistent pulmonary ...

    African Journals Online (AJOL)

    Persistent pulmonary hypertension of the newborn (PPHN) is a clinical condition characterised by severe respiratory failure and hypoxaemia.[1] Its incidence is estimated at around 2 per 1 000 live births worldwide and it is associated with a high morbidity and mortality.[2,3] Despite the progress in treating PPHN, it remains a.

  13. Persistent hyperinsulinaemic hypoglycaemia of infancy: Case report ...

    African Journals Online (AJOL)

    ... level during hypoglycaemia (insulin/glucose >0.3), the absence of ketonuria, and the need for a high dose of glucose infusion (> 15 mg/kg/min) to achieve normoglycaemia and a glycaemic response to glucagon despite the hypoglycaemia, a diagnosis of persistent hyperinsulinaemic hypoglycaemia of infancy was made.

  14. Mechanisms of HIV persistence in HIV reservoirs.

    Science.gov (United States)

    Mzingwane, Mayibongwe L; Tiemessen, Caroline T

    2017-03-01

    The establishment and maintenance of HIV reservoirs that lead to persistent viremia in patients on antiretroviral drugs remains the greatest challenge of the highly active antiretroviral therapy era. Cellular reservoirs include resting memory CD4+ T lymphocytes, implicated as the major HIV reservoir, having a half-life of approximately 44 months while this is less than 6 hours for HIV in plasma. In some individuals, persistent viremia consists of invariant HIV clones not detected in circulating resting CD4+ T lymphocytes suggesting other possible sources of residual viremia. Some anatomical reservoirs that may harbor such cells include the brain and the central nervous system, the gastrointestinal tract and the gut-associated lymphoid tissue and other lymphoid organs, and the genital tract. The presence of immune cells and other HIV susceptible cells, occurring in differing compositions in anatomical reservoirs, coupled with variable and poor drug penetration that results in suboptimal drug concentrations in some sites, are all likely factors that fuel the continued low-level replication and persistent viremia during treatment. Latently, HIV-infected CD4+ T cells harboring replication-competent virus, HIV cell-to-cell spread, and HIV-infected T cell homeostatic proliferation due to chronic immune activation represent further drivers of this persistent HIV viremia during highly active antiretroviral therapy. Copyright © 2017 John Wiley & Sons, Ltd.

  15. Undergraduate Women's Persistence in the Sciences

    Science.gov (United States)

    George-Jackson, Casey E.

    2014-01-01

    This study uses longitudinal data of undergraduate students from five public land-grant universities to better understand undergraduate students' persistence in and switching of majors, with particular attention given to women's participation in science, technology, engineering, and mathematics (STEM) fields. Specifically, the study examines…

  16. Acute, persistent quinine-induced blindness

    African Journals Online (AJOL)

    1991-05-04

    May 4, 1991 ... Acute, persistent quinine-induced blindness. A case report. P. RHEEDER, W. L. SIELlNG. Summary auinine-induced blindness arising during empirical treatment for malaria in a young man is reported. The condition was noteworthy because it was total and permanent, which is at varia.nce with other ...

  17. Ethnic Differences in Persistence with COPD Medications

    DEFF Research Database (Denmark)

    Hu, Yusun; Cantarero-Arévalo, Lourdes; Frølich, Anne

    2017-01-01

    BACKGROUND: Long-acting bronchodilators (LABDs) are recommended as a first-line maintenance therapy in patients with moderate or severe chronic obstructive pulmonary disease (COPD). The aim of the study was to explore potential ethnic differences in persistence with LABD in COPD patients. METHODS...

  18. High School Economic Composition and College Persistence

    Science.gov (United States)

    Niu, Sunny X.; Tienda, Marta

    2013-01-01

    Using a longitudinal sample of Texas high school seniors of 2002 who enrolled in college within the calendar year of high school graduation, we examine variation in college persistence according to the economic composition of their high schools, which serves as a proxy for unmeasured high school attributes that are conductive to postsecondary…

  19. Persistent pain after mastectomy with reconstruction.

    LENUS (Irish Health Repository)

    Hickey, Oonagh T

    2011-09-01

    To determine the prevalence of persistent postsurgical pain (PPSP) and its influence on functional status, and to examine associations between PPSP and single nucleotide polymorphisms of the catechol-O-methyltransferase (COMT) gene and the guanosine triphosphate cyclohydrolase 1 (GCH1) gene following mastectomy and reconstruction.

  20. Persistent Mullerian Duct Syndrome with Transverse Testicular ...

    African Journals Online (AJOL)

    The Mullerian duct regresses in male due to a glycoprotein secreted by the developing testes called. Mullerian inhibiting factor (MIF). Failure to regress may be due to lack of MIF or defective MIF receptor, resulting in various disorders of regression, and one such disorder is persistent Mullerian duct syndrome (PMDS).

  1. Persistent trophoblast disease following partial molar pregnancy.

    NARCIS (Netherlands)

    Wielsma, S.; Kerkmeijer, L.G.W.; Bekkers, R.L.M.; Pyman, J.; Tan, J.; Quinn, M.

    2006-01-01

    OBJECTIVE: Human chorionic gonadotrophin (hCG) follow-up data were analysed retrospectively in all patients registered in the Hydatidiform Mole Registry at the Royal Women's Hospital, Melbourne from January 1992 to January 2001 to determine the risk of persistent trophoblast disease following

  2. A Primer on Persistent Postconcussion Symptoms

    Science.gov (United States)

    Jantz, Paul B.

    2015-01-01

    The existence of persistent postconcussion symptoms (PPCS) is controversial, and there is ongoing debate as to whether the etiology of PPCS is psychogenic or physiogenic. In addition, there is a lack of agreement on diagnostic definitions of mild traumatic brain injury (mTBI) and concussion and the terms are used interchangeably in the research…

  3. Persistence of Value-Driven Attentional Capture

    Science.gov (United States)

    Anderson, Brian A.; Yantis, Steven

    2013-01-01

    Stimuli that have previously been associated with the delivery of reward involuntarily capture attention when presented as unrewarded and task-irrelevant distractors in a subsequent visual search task. It is unknown how long such effects of reward learning on attention persist. One possibility is that value-driven attentional biases are plastic…

  4. A Neonate with persistent hypoglycemia and seizures.

    African Journals Online (AJOL)

    MBY

    disorder was diagnosed and managed with limited success as the episodes hydroglycemic seizures persisted. ... the presence of hyperinsulinemia as the cause of the hypoglycemic dependent seizures. Case Presentation. A three day old girl was admitted to the neonatal .... the Prader-Willi syndrome, has been reported.

  5. The Myth of Persistence of Vision Revisited.

    Science.gov (United States)

    Anderson, Joseph; Anderson, Barbara

    1993-01-01

    Argues that "persistence of vision" myth (the succession of still images perceived as continuous motion) has a place in the history of film scholarship but can no longer be given currency in film theory. Suggests replacement of the concept of the passive viewer implied by the myth by an enlightened understanding of how viewers actually…

  6. The Contribution of Student Satisfaction to Persistence

    Science.gov (United States)

    Schreiner, Laurie A.; Nelson, Denise D.

    2013-01-01

    This study of nearly 30,000 undergraduates at 61 four-year public and private institutions examines the influence of satisfaction on students' persistence in college. Data were collected using the Student Satisfaction Inventory (Schreiner & Juillerat, 1994) and were analyzed by class level. The hierarchical multiple regression analyses…

  7. Retrospective review of neonates with persistent pulmonary ...

    African Journals Online (AJOL)

    Background. Persistent pulmonary hypertension of the newborn (PPHN) is a clinical syndrome characterised by high pulmonary pressures, low systemic pressures and severe hypoxaemia due to circulation transition failure after birth. Objective. To determine the incidence of and describe the risk factors, infant ...

  8. Painful bruising syndrome presenting as Persistent haematuria

    Directory of Open Access Journals (Sweden)

    Poonia Ajay

    1992-01-01

    Full Text Available A 35-year old hysterical woman had persistent gross haematuria. She started developing painful ecchymosis 4 years after the onset of haematuria. The diagnosis of painful bruising syndrome was confirmed by intracutaneous sensitivity test and the patient responded excellently to cyproheptadine.

  9. Nitrogen uptake dynamics of a persistent cyanobacterium ...

    African Journals Online (AJOL)

    Worldwide, persistent cyanobacterial blooms are becoming more frequent and are often associated with effects of global climate change. In June 2009, a widespread bloom of the unicellular cyanobacterium, Cyanothece sp., appeared in North Lake and False Bay of Lake St Lucia – a large (360 km2) estuarine lake system ...

  10. Intermediates, Catalysts, Persistence, and Boundary Steady States

    DEFF Research Database (Denmark)

    Marcondes de Freitas, Michael; Feliu, Elisenda; Wiuf, Carsten

    2017-01-01

    as cascades of a large class of post-translational modification systems (of which the MAPK cascade and the n-site futile cycle are prominent examples). Since one of the aforementioned sufficient conditions for persistence precludes the existence of boundary steady states, our method also provides a graphical...

  11. Diversity of Lactase Persistence Alleles in Ethiopia

    DEFF Research Database (Denmark)

    Jones, BL; Raga, TO; Liebert, Anke

    2013-01-01

    The persistent expression of lactase into adulthood in humans is a recent genetic adaptation that allows the consumption of milk from other mammals after weaning. In Europe, a single allele (−13910∗T, rs4988235) in an upstream region that acts as an enhancer to the expression of the lactase gene ...

  12. Primary congenital hypothyroidism complicated by persistent severe ...

    African Journals Online (AJOL)

    2013-12-24

    Dec 24, 2013 ... Case Study: Primary congenital hypothyroidism complicated by persistent severe anaemia in early infancy. 85. 2014 Volume 19 No 2. JEMDSA. Introduction. Although anaemia is a common finding in adults with hypothyroidism, there is a general paucity of studies on anaemia in infants with congenital ...

  13. Persistence of Change: Fume Hood Campaign Lessons

    Science.gov (United States)

    Feder, Elah; Robinson, Jennifer; Wakefield, Sarah

    2012-01-01

    Purpose: Sustainability initiatives typically operate for a limited time period, but it is often unclear whether they have lasting effects. The purpose of this paper is to examine a laboratory fume hood campaign, in order to identify factors that might contribute or detract from long-term change persistence. Design/methodology/approach: The…

  14. Persistence of Mycoplasma genitalium following azithromycin therapy.

    Directory of Open Access Journals (Sweden)

    Catriona S Bradshaw

    Full Text Available BACKGROUND: To determine clinical outcomes and cure rates for M.genitalium genital infection in men and women following azithromycin 1 g. METHODOLOGY: Patients attending Melbourne Sexual Health Centre between March 2005 and November 2007 with urethritis/epididymitis, cervicitis/pelvic inflammatory disease and sexual contacts of M.genitalium were tested for M.genitalium by polymerase chain reaction (PCR. M.genitalium-infection was treated with 1 g of azithromycin and a test-of-cure (toc was performed one month post-azithromycin. Response to azithromycin, and response to moxifloxacin (400 mg daily for 10 days in individuals with persistent infection post-azithromycin, was determined. PRINCIPAL FINDINGS: Of 1538 males and 313 females tested, 161 males (11% and 30 females (10% were infected with M.genitalium. A toc was available on 131 (69% infected individuals (median = 36 days [range 12-373]. Of 120 individuals prescribed azithromycin only pre-toc, M.genitalium was eradicated in 101 (84%, 95% confidence intervals [CI]: 77-90% and persisted in 19 (16%, 95% CI: 10-23%. Eleven individuals with persistent infection (9%, 95% CI: 5-15% had no risk of reinfection from untreated-partners, while eight (7%, 95% CI: 3-12% may have been at risk of reinfection from doxycycline-treated or untreated-partners. Moxifloxacin was effective in eradicating persistent infection in all cases not responding to azithromycin. Patients with persistent-M.genitalium were more likely to experience persistent symptoms (91%, compared to patients in whom M.genitalium was eradicated (17%, p<0.0001. CONCLUSION: Use of azithromycin 1 g in M.genitalium-infected patients was associated with unacceptable rates of persistent infection, which was eradicated with moxifloxacin. These findings highlight the importance of follow-up in M.genitalium-infected patients prescribed azithromycin, and the need to monitor for the development of resistance. Research to determine optimal first and

  15. Mycobacterium Lysine ε-aminotransferase is a novel alarmone metabolism related persister gene via dysregulating the intracellular amino acid level.

    Science.gov (United States)

    Duan, Xiangke; Li, Yunsong; Du, Qinglin; Huang, Qinqin; Guo, Siyao; Xu, Mengmeng; Lin, Yanping; Liu, Zhidong; Xie, Jianping

    2016-01-25

    Bacterial persisters, usually slow-growing, non-replicating cells highly tolerant to antibiotics, play a crucial role contributing to the recalcitrance of chronic infections and treatment failure. Understanding the molecular mechanism of persister cells formation and maintenance would obviously inspire the discovery of new antibiotics. The significant upregulation of Mycobacterium tuberculosis Rv3290c, a highly conserved mycobacterial lysine ε-aminotransferase (LAT) during hypoxia persistent model, suggested a role of LAT in persistence. To test this, a lat deleted Mycobacterium smegmatis was constructed. The expression of transcriptional regulator leucine-responsive regulatory protein (LrpA) and the amino acids abundance in M. smegmatis lat deletion mutants were lowered. Thus, the persistence capacity of the deletion mutant was impaired upon norfloxacin exposure under nutrient starvation. In summary, our study firstly reported the involvement of mycobacterium LAT in persister formation, and possibly through altering the intracellular amino acid metabolism balance.

  16. Chronic health conditions and depressive symptoms strongly predict persistent food insecurity among rural low-income families.

    Science.gov (United States)

    Hanson, Karla L; Olson, Christine M

    2012-08-01

    Longitudinal studies of food insecurity have not considered the unique circumstances of rural families. This study identified factors predictive of discontinuous and persistent food insecurity over three years among low-income families with children in rural counties in 13 U.S. states. Respondents reported substantial knowledge of community resources, food and finance skills, and use of formal public food assistance, yet 24% had persistent food insecurity, and another 41% were food insecure for one or two years. Multivariate multinomial regression models tested relationships between human capital, social support, financial resources, expenses, and food insecurity. Enduring chronic health conditions increased the risk of both discontinuous and persistent food insecurity. Lasting risk for depression predicted only persistent food insecurity. Education beyond high school was the only factor found protective against persistent food insecurity. Access to quality physical and mental health care services are essential to ameliorate persistent food insecurity among rural, low-income families.

  17. Persistence and resistance to extinction in the domestic dog: Basic research and applications to canine training.

    Science.gov (United States)

    Hall, Nathaniel J

    2017-08-01

    This review summarizes the research investigating behavioral persistence and resistance to extinction in the dog. The first part of this paper reviews Behavioral Momentum Theory and its applications to Applied Behavior Analysis and training of pet dogs with persistent behavioral problems. I also highlight how research on Behavioral Momentum Theory can be applied to the training of detection dogs in an attempt to enhance detection performance in the presence of behavioral disruptors common in operational settings. In the second part of this review, I highlight more basic research on behavioral persistence with dogs, and how breed differences and experiences with humans as alternative sources of reinforcement can influence dogs' resistance to extinction of a target behavior. Applied Behavior Analysis and Behavior Momentum Theory have important applications for behavioral treatments to reduce the persistence of problem behavior in dogs and for the development of enhanced training methods that enhance the persistence of working dogs. Dogs can also be leveraged as natural models of stereotypic behavior and for exploring individual differences in behavioral persistence by evaluating breed and environmental variables associated with differences in canine persistance. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Long-term persistence of pioneer species in tropical forest soil seed banks

    Energy Technology Data Exchange (ETDEWEB)

    Dalling, J W; Brown, T A

    2008-10-05

    In tropical forests, pioneer species regenerate from seeds dispersed directly into canopy gaps, and from seeds that persisted in soil seed banks before gap formation. However, life-history models suggest that selection for long-term persistence of seeds in soil should be weak, as persistence incurs a fitness cost resulting from prolonged generation time. We use a carbon dating technique to provide the first direct measurements of seed persistence in undisturbed tropical forest seed banks. We show that seeds germinate successfully from surface soil microsites up to 38 years after dispersal. Decades-long persistence may be common in pioneers with relatively large mass, and appears to be unrelated to specific regeneration requirements. In Croton billbergianus, a sub-canopy tree that recruits in abundant small gaps, long-term persistence is associated with short-distance ballistic seed dispersal. In Trema micrantha, a canopy tree with widespread dispersal, persistence is associated with a requirement for large gaps that form infrequently in old-growth forest.

  19. Consequences of the Allee effect and intraspecific competition on population persistence under adverse environmental conditions.

    Science.gov (United States)

    Petrovskii, Sergei; Blackshaw, Rod; Li, Bai-Lian

    2008-02-01

    The impact of intraspecific interactions on ecological stability and population persistence in terms of steady state(s) existence is considered theoretically based on a general competition model. We compare persistence of a structured population consisting of a few interacting (competitive) subpopulations, or groups, to persistence of the corresponding unstructured population. For a general case, we show that if the intra-group competition is stronger than the inter-group competition, then the structured population is less prone to extinction, i.e. it can persist in a parameter range where the unstructured population goes extinct. For a more specific case of a population with hierarchical competition, we show that relative viability of structured and unstructured populations depend on the type of density dependence in the population growth. Namely, while in the case of logistic growth, structured and unstructured populations exhibit equivalent persistence; in the case of Allee dynamics, the persistence of a hierarchically structured population is shown to be higher. We then apply these results to the case of behaviourally structured populations and demonstrate that an extreme form of individual aggression can be beneficial at the population level and enhance population persistence.

  20. Ciprofloxacin causes persister formation by inducing the TisB toxin in Escherichia coli.

    Directory of Open Access Journals (Sweden)

    Tobias Dörr

    2010-02-01

    Full Text Available Bacteria induce stress responses that protect the cell from lethal factors such as DNA-damaging agents. Bacterial populations also form persisters, dormant cells that are highly tolerant to antibiotics and play an important role in recalcitrance of biofilm infections. Stress response and dormancy appear to represent alternative strategies of cell survival. The mechanism of persister formation is unknown, but isolated persisters show increased levels of toxin/antitoxin (TA transcripts. We have found previously that one or more components of the SOS response induce persister formation after exposure to a DNA-damaging antibiotic. The SOS response induces several TA genes in Escherichia coli. Here, we show that a knockout of a particular SOS-TA locus, tisAB/istR, had a sharply decreased level of persisters tolerant to ciprofloxacin, an antibiotic that causes DNA damage. Step-wise administration of ciprofloxacin induced persister formation in a tisAB-dependent manner, and cells producing TisB toxin were tolerant to multiple antibiotics. TisB is a membrane peptide that was shown to decrease proton motive force and ATP levels, consistent with its role in forming dormant cells. These results suggest that a DNA damage-induced toxin controls production of multidrug tolerant cells and thus provide a model of persister formation.

  1. Review--Persistence of Listeria monocytogenes in food industry equipment and premises.

    Science.gov (United States)

    Carpentier, Brigitte; Cerf, Olivier

    2011-01-31

    To understand why Listeria monocytogenes may persist in food industry equipment and premises, notably at low temperature, scientific studies have so far focused on adhesion potential, biofilm forming ability, resistance to desiccation, acid and heat, tolerance to increased sublethal concentration of disinfectants or resistance to lethal concentrations. Evidence from studies in processing plants shows that the factors associated with the presence of L. monocytogenes are those that favor growth. Interestingly, most conditions promoting bacterial growth were shown, in laboratory assays, to decrease adhesion of L. monocytogenes cells. Good growth conditions can be found in so-called harborage sites, i.e. shelters due to unhygienic design of equipment and premises or unhygienic or damaged materials. These sites are hard to eliminate. A conceptual model of persistence/no persistence based on the relative weight of growth vs. outcome of cleaning and disinfection is suggested. It shows that a minimum initial bacterial load is necessary for bacteria to persist in a harborage site and that when a low initial bacterial charge is applied, early cleaning and disinfection is the only way to avoid persistence. We conclude by proposing that there are no strains of L. monocytogenes with unique properties that lead to persistence, but harborage sites in food industry premises and equipment where L. monocytogenes can persist. Copyright © 2011 Elsevier B.V. All rights reserved.

  2. Disruption of Membrane by Colistin Kills Uropathogenic Escherichia coli Persisters and Enhances Killing of Other Antibiotics

    Science.gov (United States)

    Cui, Peng; Niu, Hongxia; Shi, Wanliang; Zhang, Shuo; Zhang, Hao; Margolick, Joseph

    2016-01-01

    Persisters are small populations of quiescent bacterial cells that survive exposure to bactericidal antibiotics and are responsible for many persistent infections and posttreatment relapses. However, little is known about how to effectively kill persister bacteria. In the work presented here, we found that colistin, a membrane-active antibiotic, was highly active against Escherichia coli persisters at high concentrations (25 or 50 μg/ml). At a clinically relevant lower concentration (10 μg/ml), colistin alone had no apparent effect on E. coli persisters. In combination with other drugs, this concentration of colistin enhanced the antipersister activity of gentamicin and ofloxacin but not that of ampicillin, nitrofurans, and sulfa drugs in vitro. The colistin enhancement effect was most likely due to increased uptake of the other antibiotics, as demonstrated by increased accumulation of fluorescence-labeled gentamicin. Interestingly, colistin significantly enhanced the activity of ofloxacin and nitrofurantoin but not that of gentamicin or sulfa drugs in the murine model of urinary tract infection. Our findings suggest that targeting bacterial membranes is a valuable approach to eradicating persisters and should have implications for more effective treatment of persistent bacterial infections. PMID:27600051

  3. The persistence of regional unemployment: evidence from China

    OpenAIRE

    Wu, Z

    2003-01-01

    The purpose of this paper is to examine the persistence of regional unemployment and to explore the sources of this persistence. Evidence from China suggests three empirical findings. First, provincial relative unemployment is more persistent than aggregate unemployment. Second, youth unemployment is less persistent than total unemployment. Third, although the western region has the highest provincial unemployment rate, it has the lowest persistence of regional unemployment. To explore the so...

  4. Mexican Americans in Higher Education: Cultural Adaptation and Marginalization as Predictors of College Persistence Intentions and Life Satisfaction

    Science.gov (United States)

    Ojeda, Lizette; Castillo, Linda G.; Rosales Meza, Rocío; Piña-Watson, Brandy

    2014-01-01

    This study examined how college persistence intentions and life satisfaction influenced by acculturation, enculturation, White marginalization, and Mexican American marginalization among 515 Mexican American college students. The utility of a path analysis model was supported. Enculturation positively predicted persistence and life satisfaction.…

  5. Volcanoes and climate: Krakatoa's signature persists in the ocean.

    Science.gov (United States)

    Gleckler, P J; Wigley, T M L; Santer, B D; Gregory, J M; Achutarao, K; Taylor, K E

    2006-02-09

    We have analysed a suite of 12 state-of-the-art climate models and show that ocean warming and sea-level rise in the twentieth century were substantially reduced by the colossal eruption in 1883 of the volcano Krakatoa in the Sunda strait, Indonesia. Volcanically induced cooling of the ocean surface penetrated into deeper layers, where it persisted for decades after the event. This remarkable effect on oceanic thermal structure is longer lasting than has previously been suspected and is sufficient to offset a large fraction of ocean warming and sea-level rise caused by anthropogenic influences.

  6. Persistence of travelling waves in a generalized Fisher equation

    International Nuclear Information System (INIS)

    Kyrychko, Yuliya N.; Blyuss, Konstantin B.

    2009-01-01

    Travelling waves of the Fisher equation with arbitrary power of nonlinearity are studied in the presence of long-range diffusion. Using analogy between travelling waves and heteroclinic solutions of corresponding ODEs, we employ the geometric singular perturbation theory to prove the persistence of these waves when the influence of long-range effects is small. When the long-range diffusion coefficient becomes larger, the behaviour of travelling waves can only be studied numerically. In this case we find that starting with some values, solutions of the model lose monotonicity and become oscillatory

  7. Persistence of soil organic matter as an ecosystem property

    Energy Technology Data Exchange (ETDEWEB)

    Schmidt, M.W.; Torn, M. S.; Abiven, S.; Dittmar, T.; Guggenberger, G.; Janssens, I.A.; Kleber, M.; Kögel-Knabner, I.; Lehmann, J.; Manning, D.A.C.; Nannipieri, P.; Rasse, D.P.; Weiner, S.; Trumbore, S.E.

    2011-08-15

    Globally, soil organic matter (SOM) contains more than three times as much carbon as either the atmosphere or terrestrial vegetation. Yet it remains largely unknown why some SOM persists for millennia whereas other SOM decomposes readily—and this limits our ability to predict how soils will respond to climate change. Recent analytical and experimental advances have demonstrated that molecular structure alone does not control SOM stability: in fact, environmental and biological controls predominate. Here we propose ways to include this understanding in a new generation of experiments and soil carbon models, thereby improving predictions of the SOM response to global warming.

  8. Predicting medication persistence to buprenorphine transdermal system.

    Science.gov (United States)

    Pergolizzi, Joseph V; Ben-Joseph, Rami; Chang, Chun-Lan; Hess, Gregory

    2015-02-01

    Persistence, the duration a patient remains on therapy, in chronic, symptomatic conditions plays an important role in therapy effectiveness. Understanding the duration and patient factors associated with prescribed medication persistence is, therefore, an important step toward better treatment and health outcomes for patients. In the following study, an analysis of such factors associated with buprenorphine transdermal system (BTDS) persistence was conducted utilizing a large US private practitioner and pharmacy claims database and is herein reported. Patients aged ≥ 18 years initiating BTDS during January 1, 2011-November 30, 2011 were identified in the IMS Private Practitioner Medical Claims and Pharmacy Claims databases. An index date was defined as the first prescription of BTDS during the studied interval. During the preindex period, Charlson Comorbidity Index (CCI), chronic pain-related conditions, and prior medication use were assessed. Concomitant medications and various treatment patterns (eg, last dose strength and dose adjustments) were assessed in the postindex 6-month period. Persistence was measured as the duration of BTDS from initiation to the 1st >28-day refill gap in the postindex 6-month period. Descriptive statistical and survival analysis was used to assess the predictors of BTDS persistence. During the study period, 10,457 patients newly treated with BTDS were identified. Patients' mean (± SD) age was 54.5 (± 15.2) years; 69.9% were women, and the mean (± SD) CCI was 1 (± 1.4). Utilizing a hierarchical approach, patients were separated into different cohorts based on the initial analgesic prescription identified during postindex period with 91.7%, 34.7%, and 59.0% of the patients using opioids, NSAIDs and adjuvant analgesics, respectively. Multivariate regression analyses showed that patients with prior opioid and adjuvant analgesic use were 21% and 5% less likely to discontinue BTDS (P 5 mcg/hour. Sensitivity analyses for those with 30

  9. Phenotypic and genetic heterogeneity within biofilms with particular emphasis on persistence and antimicrobial tolerance.

    Science.gov (United States)

    Sadiq, Faizan A; Flint, Steve; Li, YanJun; Ou, Kai; Yuan, Lei; He, Guo Qing

    2017-09-01

    Phenotypic changes or phase variation within biofilms is an important feature of bacterial dormant life. Enhanced resistance to antimicrobials is one of the distinct features displayed by a fraction of cells within biofilms. It is believed that persisters are mainly responsible for this phenotypic heterogeneity. However, there is still an unresolved debate on the formation of persisters. In this short review, we highlight all known genomic and proteomic changes encountered by bacterial cells within biofilms. We have also described all phenotypic changes displayed by bacterial cells within biofilms with particular emphasis on enhanced antimicrobial tolerance of biofilms with particular reference to persisters. In addition, all currently known models of persistence have been succinctly discussed.

  10. Ciclo de Vida das Empresas, Book-Tax Differences e a Persistência nos Lucros

    Directory of Open Access Journals (Sweden)

    Antonio Lopo Martinez

    2016-01-01

    Full Text Available The objective in this study is to show if the life cycle explains the relation between the Book-Tax Differences (BTDs and earnings persistence, as well as to inform on the future gains and their relation with the BTDs. Therefore, univariate tests were applied to verify the differences between the mean BTDS, life cycle stages and regression coefficient for the Earnings Before Income Tax (EBIT. The study focused on Brazilian publicly traded companies between 2009 and 2013. The results indicated that the control of earnings persistence was related with the stages of the life cycle. The information relevance of the life cycle and the Book-Tax Differences for earnings persistence is registered. In conclusion, the firm life cycle should be included in the analysis of the relation between the BTDs and earnings persistence. The evidence registered here is crucial to identify the quality of the earnings and incorporate them into earnings valuation models.

  11. Intracellular survival of Staphylococcus aureus during persistent infection in the insect Tenebrio molitor.

    Science.gov (United States)

    McGonigle, John E; Purves, Joanne; Rolff, Jens

    2016-06-01

    Survival of bacteria within host cells and tissues presents a challenge to the immune systems of higher organisms. Escape from phagocytic immune cells compounds this issue, as immune cells become potential vehicles for pathogen dissemination. However, the duration of persistence within phagocytes and its contribution to pathogen load has yet to be determined. We investigate the immunological significance of intracellular persistence within the insect model Tenebrio molitor, assessing the extent, duration and location of bacterial recovery during a persistent infection. Relative abundance of Staphylococcus aureus in both intracellular and extracellular fractions was determined over 21 days, and live S. aureus were successfully recovered from both the hemolymph and within phagocytic immune cells across the entire time course. The proportion of bacteria recovered from within phagocytes also increased over time. Our results show that to accurately estimate pathogen load it is vital to account for bacteria persisting within immune cells. Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. Foxp3+ regulatory T cells control persistence of viral CNS infection.

    Directory of Open Access Journals (Sweden)

    Dajana Reuter

    Full Text Available We earlier established a model of a persistent viral CNS infection using two week old immunologically normal (genetically unmodified mice and recombinant measles virus (MV. Using this model infection we investigated the role of regulatory T cells (Tregs as regulators of the immune response in the brain, and assessed whether the persistent CNS infection can be modulated by manipulation of Tregs in the periphery. CD4(+ CD25(+ Foxp3(+ Tregs were expanded or depleted during the persistent phase of the CNS infection, and the consequences for the virus-specific immune response and the extent of persistent infection were analyzed. Virus-specific CD8(+ T cells predominantly recognising the H-2D(b-presented viral hemagglutinin epitope MV-H(22-30 (RIVINREHL were quantified in the brain by pentamer staining. Expansion of Tregs after intraperitoneal (i.p. application of the superagonistic anti-CD28 antibody D665 inducing transient immunosuppression caused increased virus replication and spread in the CNS. In contrast, depletion of Tregs using diphtheria toxin (DT in DEREG (depletion of regulatory T cells-mice induced an increase of virus-specific CD8(+ effector T cells in the brain and caused a reduction of the persistent infection. These data indicate that manipulation of Tregs in the periphery can be utilized to regulate virus persistence in the CNS.

  13. Predictors of caregiver feeding practices differentiating persistently obese from persistently non-overweight adolescents ✩

    OpenAIRE

    Towner, Elizabeth K.; Reiter-Purtill, Jennifer; Boles, Richard E.; Zeller, Meg H.

    2014-01-01

    Understanding the contribution of caregiver feeding practices to adolescent diet and weight is important to refining caregiver roles within the context of adolescent obesity prevention and treatment. This secondary data analysis examined whether feeding practices of female caregivers differentiated persistently non-overweight (n = 29) from persistently obese (n = 47) adolescents. Families who previously participated in a cross-sectional study on correlates of obesity were recruited for this f...

  14. Geometry Helps to Compare Persistence Diagrams

    Energy Technology Data Exchange (ETDEWEB)

    Kerber, Michael; Morozov, Dmitriy; Nigmetov, Arnur

    2015-11-16

    Exploiting geometric structure to improve the asymptotic complexity of discrete assignment problems is a well-studied subject. In contrast, the practical advantages of using geometry for such problems have not been explored. We implement geometric variants of the Hopcroft--Karp algorithm for bottleneck matching (based on previous work by Efrat el al.), and of the auction algorithm by Bertsekas for Wasserstein distance computation. Both implementations use k-d trees to replace a linear scan with a geometric proximity query. Our interest in this problem stems from the desire to compute distances between persistence diagrams, a problem that comes up frequently in topological data analysis. We show that our geometric matching algorithms lead to a substantial performance gain, both in running time and in memory consumption, over their purely combinatorial counterparts. Moreover, our implementation significantly outperforms the only other implementation available for comparing persistence diagrams.

  15. Persisting weakness after withdrawal of a statin.

    Science.gov (United States)

    Mygland, Åse; Ljøstad, Unn; Krossnes, Bård Kronen

    2014-04-08

    An 81-year-old woman treated with simvastatin for several years followed by atorvastatin for about 1 year presented with fatigue, weakness and unsteady gait. The finding of elevated creatine kinase (CK) and symmetric muscle weakness around shoulders and hips led to suspicion of a toxic statin-associated myopathy. Atorvastatin was withdrawn, but her weakness persisted. Owing to persisting weakness, an autoimmune myopathy (myositis) was suspected, but initially disregarded since a muscle biopsy showed necrotic muscle fibres without inflammatory cell infiltrates and myositis-specific autoantibodies were absent. After 18 months with slowly progressive weakness and increasing CK values, awareness of new knowledge about autoimmunity as a cause of necrotic myopathy, led to a successful treatment trial with intravenous immunoglobulines, followed by steroids and metothrexate. Antibodies to the target enzyme of statins (HMGCR (3-hydroksy-3-methylglutaryl-coenzyme A reductase)) were detected in her serum, and she was diagnosed with autoimmune necrotic myositis probably triggered by atorvastatin.

  16. On the brink between extinction and persistence

    Directory of Open Access Journals (Sweden)

    Bach Lars A

    2008-11-01

    Full Text Available Abstract The nature of size fluctuations is crucial in forecasting future population persistence, independently of whether the variability stems from external forces or from the dynamics of the population renewal process. The risk of intercepting zero is highly dependent on the way the variance of the population size relates to its mean. The minimum population size required for a population not to go extinct can be determined by a scaling equation relating the variance to the arithmetic mean. By the use of a derived expression for the harmonic mean defined by the parameters of the scaling equation we show how it is possible to separate the domains of persistence from those of extinction and to facilitate the identification of populations on the brink of extinction. Reviewers This article was reviewed by Mark W. Schwartz (nominated by Peter Olofsson, Josef Bryja (nominated by Aniko Szabo and Wai-YuanTan. For the full reviews, please go to the Reviewers' Comments section.

  17. Temporal persistence of anomalous self-experience

    DEFF Research Database (Denmark)

    Nordgaard, J; Handest, P; Vollmer-Larsen, A

    2017-01-01

    at baseline and follow-up to assess self-disorders. The scale was a pre-cursor of the later published EASE-scale. Additionally, we examined the development of positive and negative syndromes and of the Global Assessment of Functioning (GAF). RESULTS: There was a high correlation between self-disorders......BACKGROUND: The concept of self-disorders in schizophrenia has gained substantial interest and it has now been established empirically that self-disorders aggregate in schizophrenia-spectrum disorders but not in other mental disorders or in healthy controls. Yet, the issue of temporal persistence...... has not been addressed. AIM: The aim of this study is to examine the temporal persistence of self-disorders. METHODS: 96 first admission patients were thoroughly assessed for psychopathology including SD at baseline and again 5years later. We created a 25-item self-disorder scale which was used both...

  18. Persistent Aerial Tracking system for UAVs

    KAUST Repository

    Mueller, Matthias

    2016-12-19

    In this paper, we propose a persistent, robust and autonomous object tracking system for unmanned aerial vehicles (UAVs) called Persistent Aerial Tracking (PAT). A computer vision and control strategy is applied to a diverse set of moving objects (e.g. humans, animals, cars, boats, etc.) integrating multiple UAVs with a stabilized RGB camera. A novel strategy is employed to successfully track objects over a long period, by ‘handing over the camera’ from one UAV to another. We evaluate several state-of-the-art trackers on the VIVID aerial video dataset and additional sequences that are specifically tailored to low altitude UAV target tracking. Based on the evaluation, we select the leading tracker and improve upon it by optimizing for both speed and performance, integrate the complete system into an off-the-shelf UAV, and obtain promising results showing the robustness of our solution in real-world aerial scenarios.

  19. Mechanisms of Toxoplasma gondii persistence and latency

    Science.gov (United States)

    Sullivan, William J.; Jeffers, Victoria

    2011-01-01

    Toxoplasma gondii is an obligate intracellular protozoan parasite that causes opportunistic disease, particularly in immunocompromised individuals. Central to its transmission and pathogenesis is the ability of the proliferative stage (tachyzoite) to convert into latent tissue cysts (bradyzoites). Encystment allows Toxoplasma to persist in the host, and affords the parasite a unique opportunity to spread to new hosts without proceeding through its sexual stage, which is restricted to felids. Bradyzoite tissue cysts can cause reactivated toxoplasmosis if host immunity becomes impaired. A greater understanding of the molecular mechanisms orchestrating bradyzoite development is needed to better manage the disease. Here we will review key studies that have contributed to our knowledge about this persistent form of the parasite and how to study it, with a focus on how cellular stress can signal for the reprogramming of gene expression needed during bradyzoite development. PMID:22091606

  20. [Diastema verum and persistent labial frenum].

    Science.gov (United States)

    Belic, D; Obrez-Oblak, K

    1990-01-01

    In the management of diastema verum associated with persistent labial frenum it is important to distinguish, on the basis of clinical testing, between a normal and abnormal labial frenum. The authors believe that from an orthodontic standpoint, frenotomy ad frenectomy are contraindicated in the deciduous dentition. The latter procedure is indicated in a mixed dentition and is best carried out before the eruption of lateral incisors.