WorldWideScience

Sample records for multifactorial threshold model

  1. Toward a multifactorial model of expertise: beyond born versus made.

    Science.gov (United States)

    Hambrick, David Z; Burgoyne, Alexander P; Macnamara, Brooke N; Ullén, Fredrik

    2018-02-15

    The debate over the origins of individual differences in expertise has raged for over a century in psychology. The "nature" view holds that expertise reflects "innate talent"-that is, genetically determined abilities. The "nurture" view counters that, if talent even exists, its effects on ultimate performance are negligible. While no scientist takes seriously a strict nature-only view of expertise, the nurture view has gained tremendous popularity over the past several decades. This environmentalist view holds that individual differences in expertise reflect training history, with no important contribution to ultimate performance by innate ability ("talent"). Here, we argue that, despite its popularity, this view is inadequate to account for the evidence concerning the origins of expertise that has accumulated since the view was first proposed. More generally, we argue that the nature versus nurture debate in research on expertise is over-or certainly should be, as it has been in other areas of psychological research for decades. We describe a multifactorial model for research on the nature and nurture of expertise, which we believe will provide a progressive direction for future research on expertise. © 2018 New York Academy of Sciences.

  2. Viewing a Phonological Deficit within a Multifactorial Model of Dyslexia

    Science.gov (United States)

    Catts, Hugh W.; McIlraith, Autumn; Bridges, Mindy Sittner; Nielsen, Diane Corcoran

    2017-01-01

    Participants were administered multiple measures of phonological awareness, oral language, and rapid automatized naming at the beginning of kindergarten and multiple measures of word reading at the end of second grade. A structural equation model was fit to the data and latent scores were used to identify children with a deficit in phonological…

  3. Multifactorial modelling of high-temperature treatment of timber in the saturated water steam medium

    Science.gov (United States)

    Prosvirnikov, D. B.; Safin, R. G.; Ziatdinova, D. F.; Timerbaev, N. F.; Lashkov, V. A.

    2016-04-01

    The paper analyses experimental data obtained in studies of high-temperature treatment of softwood and hardwood in an environment of saturated water steam. Data were processed in the Curve Expert software for the purpose of statistical modelling of processes and phenomena occurring during this process. The multifactorial modelling resulted in the empirical dependences, allowing determining the main parameters of this type of hydrothermal treatment with high accuracy.

  4. Multifactorial causal model of brain (dis)organization and therapeutic intervention: Application to Alzheimer's disease.

    Science.gov (United States)

    Iturria-Medina, Yasser; Carbonell, Félix M; Sotero, Roberto C; Chouinard-Decorte, Francois; Evans, Alan C

    2017-05-15

    Generative models focused on multifactorial causal mechanisms in brain disorders are scarce and generally based on limited data. Despite the biological importance of the multiple interacting processes, their effects remain poorly characterized from an integrative analytic perspective. Here, we propose a spatiotemporal multifactorial causal model (MCM) of brain (dis)organization and therapeutic intervention that accounts for local causal interactions, effects propagation via physical brain networks, cognitive alterations, and identification of optimum therapeutic interventions. In this article, we focus on describing the model and applying it at the population-based level for studying late onset Alzheimer's disease (LOAD). By interrelating six different neuroimaging modalities and cognitive measurements, this model accurately predicts spatiotemporal alterations in brain amyloid-β (Aβ) burden, glucose metabolism, vascular flow, resting state functional activity, structural properties, and cognitive integrity. The results suggest that a vascular dysregulation may be the most-likely initial pathologic event leading to LOAD. Nevertheless, they also suggest that LOAD it is not caused by a unique dominant biological factor (e.g. vascular or Aβ) but by the complex interplay among multiple relevant direct interactions. Furthermore, using theoretical control analysis of the identified population-based multifactorial causal network, we show the crucial advantage of using combinatorial over single-target treatments, explain why one-target Aβ based therapies might fail to improve clinical outcomes, and propose an efficiency ranking of possible LOAD interventions. Although still requiring further validation at the individual level, this work presents the first analytic framework for dynamic multifactorial brain (dis)organization that may explain both the pathologic evolution of progressive neurological disorders and operationalize the influence of multiple interventional

  5. Inherited behaviors, BDNF expression and response to treatment in a novel multifactorial rat model for depression.

    Science.gov (United States)

    Gersner, Roman; Gal, Ram; Levit, Ofir; Moshe, Hagar; Zangen, Abraham

    2014-06-01

    Major depressive disorder (MDD) is a common and devastating mental illness behaviorally characterized by various symptoms, including reduced motivation, anhedonia and psychomotor retardation. Although the etiology of MDD is still obscure, a genetic predisposition appears to play an important role. Here we used, for the first time, a multifactorial selective breeding procedure to generate a distinct 'depressed' rat line (DRL); our selection was based upon mobility in the forced swim test, sucrose preference and home-cage locomotion, three widely used tests associated with core characteristics of MDD. Other behavioral effects of the selection process, as well as changes in brain-derived neurotrophic factor (BDNF) and the response to three antidepressant treatments, were also examined. We show that decreased mobility in the forced swim test and decreased sucrose preference (two directly selected traits), as well as decreased exploration in the open field test (an indirectly selected trait), are hereditary components in DRL rats. In addition, lower BDNF levels are observed in the dorsal hippocampus of DRL rats, complying with the neurotrophic hypothesis of depression. Finally, electroconvulsive shocks (ECS) but not pharmacological treatment normalizes both the depressive-like behavioral impairments and the BDNF-related molecular alterations in DRL rats, highlighting the need for robust treatment when the disease is inherited and not necessarily triggered by salient chronic stress. We therefore provide a novel multifactorial genetic rat model for depression-related behaviors. The model can be used to further study the etiology of the disease and suggest molecular correlates and possible treatments for the disease.

  6. The role of cognitive and visual abilities as predictors in the Multifactorial Model of Driving Safety.

    Science.gov (United States)

    Anstey, Kaarin J; Horswill, Mark S; Wood, Joanne M; Hatherly, Christopher

    2012-03-01

    The current study evaluated part of the Multifactorial Model of Driving Safety to elucidate the relative importance of cognitive function and a limited range of standard measures of visual function in relation to the Capacity to Drive Safely. Capacity to Drive Safely was operationalized using three validated screening measures for older drivers. These included an adaptation of the well validated Useful Field of View (UFOV) and two newer measures, namely a Hazard Perception Test (HPT), and a Hazard Change Detection Task (HCDT). Community dwelling drivers (n=297) aged 65-96 were assessed using a battery of measures of cognitive and visual function. Factor analysis of these predictor variables yielded factors including Executive/Speed, Vision (measured by visual acuity and contrast sensitivity), Spatial, Visual Closure, and Working Memory. Cognitive and Vision factors explained 83-95% of age-related variance in the Capacity to Drive Safely. Spatial and Working Memory were associated with UFOV, HPT and HCDT, Executive/Speed was associated with UFOV and HCDT and Vision was associated with HPT. The Capacity to Drive Safely declines with chronological age, and this decline is associated with age-related declines in several higher order cognitive abilities involving manipulation and storage of visuospatial information under speeded conditions. There are also age-independent effects of cognitive function and vision that determine driving safety. Copyright © 2011 Elsevier Ltd. All rights reserved.

  7. Visualizing multifactorial and multi-attribute effect sizes in linear mixed models with a view towards sensometrics

    DEFF Research Database (Denmark)

    and straightforward idea is to interpret effects relative to the residual error and to choose the proper effect size measure. For multi-attribute bar plots of F-statistics this amounts, in balanced settings, to a simple transformation of the bar heights to get them transformed into depicting what can be seen...... on a multifactorial sensory profile data set and compared to actual d-prime calculations based on ordinal regression modelling through the ordinal package. A generic ``plug-in'' implementation of the method is given in the SensMixed package, which again depends on the lmerTest package. We discuss and clarify the bias...

  8. Thresholding projection estimators in functional linear models

    OpenAIRE

    Cardot, Hervé; Johannes, Jan

    2010-01-01

    We consider the problem of estimating the regression function in functional linear regression models by proposing a new type of projection estimators which combine dimension reduction and thresholding. The introduction of a threshold rule allows to get consistency under broad assumptions as well as minimax rates of convergence under additional regularity hypotheses. We also consider the particular case of Sobolev spaces generated by the trigonometric basis which permits to get easily mean squ...

  9. Maturity-onset diabetes of the young as a model for elucidating the multifactorial origin of type 2 diabetes mellitus.

    Science.gov (United States)

    Horikawa, Yukio

    2018-02-06

    Maturity-onset diabetes of the young (MODY) is a form of diabetes classically characterized as having autosomal dominant inheritance, onset before the age of 25 years in at least one family member and partly preserved pancreatic β-cell function. The 14 responsible genes are reported to be MODY type 1~14, of which MODY 2 and 3 might be the most common forms. Although MODY is currently classified as diabetes of a single gene defect, it has become clear that mutations in rare MODYs, such as MODY 5 and MODY 6, have small mutagenic effects and low penetrance. In addition, as there are differences in the clinical phenotypes caused by the same mutation even in the same family, other phenotypic modifying factors are thought to exist; MODY could well have characteristics of type 2 diabetes mellitus, which is of multifactorial origin. Here, we outline the effects of genetic and environmental factors on the known phenotypes of MODY, focusing mainly on the examples of MODY 5 and 6, which have low penetrance, as suggestive models for elucidating the multifactorial origin of type 2 diabetes mellitus. © 2018 The Authors. Journal of Diabetes Investigation published by Asian Association for the Study of Diabetes (AASD) and John Wiley & Sons Australia, Ltd.

  10. Differential equation models for sharp threshold dynamics.

    Science.gov (United States)

    Schramm, Harrison C; Dimitrov, Nedialko B

    2014-01-01

    We develop an extension to differential equation models of dynamical systems to allow us to analyze probabilistic threshold dynamics that fundamentally and globally change system behavior. We apply our novel modeling approach to two cases of interest: a model of infectious disease modified for malware where a detection event drastically changes dynamics by introducing a new class in competition with the original infection; and the Lanchester model of armed conflict, where the loss of a key capability drastically changes the effectiveness of one of the sides. We derive and demonstrate a step-by-step, repeatable method for applying our novel modeling approach to an arbitrary system, and we compare the resulting differential equations to simulations of the system's random progression. Our work leads to a simple and easily implemented method for analyzing probabilistic threshold dynamics using differential equations. Published by Elsevier Inc.

  11. Optimisation of distributed maintenance: Modelling and application to the multi-factory production

    Energy Technology Data Exchange (ETDEWEB)

    Simeu-Abazi, Zineb, E-mail: Zineb.Simeu-Abazi@g-scop.inpg.fr [Laboratory G-SCOP, 46 Avenue Felix Viallet, 38031 Grenoble Cedex 1 (France); Ahmad, Alali Alhouaij [Laboratory G-SCOP, 46 Avenue Felix Viallet, 38031 Grenoble Cedex 1 (France)

    2011-11-15

    This paper concerns the modelling and the cost evaluation of maintenance activities in a distributed context. In this work we study the particular case where the maintenance activities are executed by two workshops: a central maintenance workshop (CMW) and a mobile maintenance workshop (MMW). The CMW concerns the repairing process for the corrective maintenance and the MMW executes all preventive maintenance in several factories according to a defined scheduling. The aim is to take into account the resources (spare parts in the MMW) and maintenance actions for a given operating budget. A modular approach for modelling a multi-site structure is proposed to achieve the aim of improving the availability of facilities on production sites while minimising the cost of maintenance.

  12. Development and Evaluation of a Simple, Multifactorial Model Based on Landing Performance to Indicate Injury Risk in Surfing Athletes.

    Science.gov (United States)

    Lundgren, Lina E; Tran, Tai T; Nimphius, Sophia; Raymond, Ellen; Secomb, Josh L; Farley, Oliver R L; Newton, Robert U; Steele, Julie R; Sheppard, Jeremy M

    2015-11-01

    To develop and evaluate a multifactorial model based on landing performance to estimate injury risk for surfing athletes. Five measures were collected from 78 competitive surfing athletes and used to create a model to serve as a screening tool for landing tasks and potential injury risk. In the second part of the study, the model was evaluated using junior surfing athletes (n = 32) with a longitudinal follow-up of their injuries over 26 wk. Two models were compared based on the collected data, and magnitude-based inferences were applied to determine the likelihood of differences between injured and noninjured groups. The study resulted in a model based on 5 measures--ankle-dorsiflexion range of motion, isometric midthigh-pull lower-body strength, time to stabilization during a drop-and-stick (DS) landing, relative peak force during a DS landing, and frontal-plane DS-landing video analysis--for male and female professional surfers and male and female junior surfers. Evaluation of the model showed that a scaled probability score was more likely to detect injuries in junior surfing athletes and reported a correlation of r = .66, P = .001, with a model of equal variable importance. The injured (n = 7) surfers had a lower probability score (0.18 ± 0.16) than the noninjured group (n = 25, 0.36 ± 0.15), with 98% likelihood, Cohen d = 1.04. The proposed model seems sensitive and easy to implement and interpret. Further research is recommended to show full validity for potential adaptations for other sports.

  13. Gauge threshold corrections for local string models

    International Nuclear Information System (INIS)

    Conlon, Joseph P.

    2009-01-01

    We study gauge threshold corrections for local brane models embedded in a large compact space. A large bulk volume gives important contributions to the Konishi and super-Weyl anomalies and the effective field theory analysis implies the unification scale should be enhanced in a model-independent way from M s to RM s . For local D3/D3 models this result is supported by the explicit string computations. In this case the scale RM s comes from the necessity of global cancellation of RR tadpoles sourced by the local model. We also study D3/D7 models and discuss discrepancies with the effective field theory analysis. We comment on phenomenological implications for gauge coupling unification and for the GUT scale.

  14. Mob control models of threshold collective behavior

    CERN Document Server

    Breer, Vladimir V; Rogatkin, Andrey D

    2017-01-01

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

  15. A threshold model of investor psychology

    Science.gov (United States)

    Cross, Rod; Grinfeld, Michael; Lamba, Harbir; Seaman, Tim

    2005-08-01

    We introduce a class of agent-based market models founded upon simple descriptions of investor psychology. Agents are subject to various psychological tensions induced by market conditions and endowed with a minimal ‘personality’. This personality consists of a threshold level for each of the tensions being modeled, and the agent reacts whenever a tension threshold is reached. This paper considers an elementary model including just two such tensions. The first is ‘cowardice’, which is the stress caused by remaining in a minority position with respect to overall market sentiment and leads to herding-type behavior. The second is ‘inaction’, which is the increasing desire to act or re-evaluate one's investment position. There is no inductive learning by agents and they are only coupled via the global market price and overall market sentiment. Even incorporating just these two psychological tensions, important stylized facts of real market data, including fat-tails, excess kurtosis, uncorrelated price returns and clustered volatility over the timescale of a few days are reproduced. By then introducing an additional parameter that amplifies the effect of externally generated market noise during times of extreme market sentiment, long-time volatility correlations can also be recovered.

  16. Synergistic effects in threshold models on networks

    Science.gov (United States)

    Juul, Jonas S.; Porter, Mason A.

    2018-01-01

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

  17. Model Threshold untuk Pembelajaran Memproduksi Pantun Kelas XI

    Directory of Open Access Journals (Sweden)

    Fitri Nura Murti

    2017-03-01

    Full Text Available Abstract: The learning pantun method in schools provided less opportunity to develop the students’ creativity in producing pantun. This situation was supported by the result of the observation conducted on eleventh graders at SMAN 2 Bondowoso. It showed that the students tend to plagiarize their pantun. The general objective of this research and development is to develop Threshold Pantun model for learning to produce pantun for elevent graders. The product was presented in guidance book for teachers entitled “Pembelajaran Memproduksi Pantun Menggunakan Model Threshold Pantun untuk Kelas XI”. This study adapted design method of Borg-Gall’s R&D procedure. The result of this study showed that Threshold Pantun model was appropriate to be implemented for learning to produce pantun. Key Words: Threshold Pantun model, produce pantun Abstrak: Pembelajaran pantun di sekolah selama ini kurang mengembangkan kreativitas siswa dalam memproduksi pantun. Hal tersebut dikuatkan oleh hasil observasi siswa kelas XI SMAN 2 Bondowoso yang menunjukkan adanya kecenderungan produk siswa bersifat plagiat. Tujuan penelitian dan pengembangan ini secara umum adalah mengembangkan model Threshold Pantun untuk pembelajaran memproduksi pantun kelas XI..Produk disajikan dalam bentuk buku panduan bagi guru dengan judul “Pembelajaran Memproduksi Pantun Menggunakan Model Threshold Pantun untuk Kelas XI”. Penelitian ini menggunakan rancangan penelitian yang diadaptasi dari prosedur penelitian dan pengembangan Borg dan Gall. Berdasarkan hasil validasi model Threshold Pantun untuk pembelajaran memproduksi pantun layak diimplementasikan. Kata kunci: model Threshold Pantun, memproduksi pantun

  18. A multifactorial likelihood model for MMR gene variant classification incorporating probabilities based on sequence bioinformatics and tumor characteristics: a report from the Colon Cancer Family Registry.

    Science.gov (United States)

    Thompson, Bryony A; Goldgar, David E; Paterson, Carol; Clendenning, Mark; Walters, Rhiannon; Arnold, Sven; Parsons, Michael T; Michael D, Walsh; Gallinger, Steven; Haile, Robert W; Hopper, John L; Jenkins, Mark A; Lemarchand, Loic; Lindor, Noralane M; Newcomb, Polly A; Thibodeau, Stephen N; Young, Joanne P; Buchanan, Daniel D; Tavtigian, Sean V; Spurdle, Amanda B

    2013-01-01

    Mismatch repair (MMR) gene sequence variants of uncertain clinical significance are often identified in suspected Lynch syndrome families, and this constitutes a challenge for both researchers and clinicians. Multifactorial likelihood model approaches provide a quantitative measure of MMR variant pathogenicity, but first require input of likelihood ratios (LRs) for different MMR variation-associated characteristics from appropriate, well-characterized reference datasets. Microsatellite instability (MSI) and somatic BRAF tumor data for unselected colorectal cancer probands of known pathogenic variant status were used to derive LRs for tumor characteristics using the Colon Cancer Family Registry (CFR) resource. These tumor LRs were combined with variant segregation within families, and estimates of prior probability of pathogenicity based on sequence conservation and position, to analyze 44 unclassified variants identified initially in Australasian Colon CFR families. In addition, in vitro splicing analyses were conducted on the subset of variants based on bioinformatic splicing predictions. The LR in favor of pathogenicity was estimated to be ~12-fold for a colorectal tumor with a BRAF mutation-negative MSI-H phenotype. For 31 of the 44 variants, the posterior probabilities of pathogenicity were such that altered clinical management would be indicated. Our findings provide a working multifactorial likelihood model for classification that carefully considers mode of ascertainment for gene testing. © 2012 Wiley Periodicals, Inc.

  19. Eigen's Error Threshold and Mutational Meltdown in a Quasispecies Model

    OpenAIRE

    Bagnoli, F.; Bezzi, M.

    1998-01-01

    We introduce a toy model for interacting populations connected by mutations and limited by a shared resource. We study the presence of Eigen's error threshold and mutational meltdown. The phase diagram of the system shows that the extinction of the whole population due to mutational meltdown can occur well before an eventual error threshold transition.

  20. Thresholds and Smooth Transitions in Vector Autoregressive Models

    DEFF Research Database (Denmark)

    Hubrich, Kirstin; Teräsvirta, Timo

    This survey focuses on two families of nonlinear vector time series models, the family of Vector Threshold Regression models and that of Vector Smooth Transition Regression models. These two model classes contain incomplete models in the sense that strongly exogeneous variables are allowed in the...

  1. Threshold model of cascades in empirical temporal networks

    Science.gov (United States)

    Karimi, Fariba; Holme, Petter

    2013-08-01

    Threshold models try to explain the consequences of social influence like the spread of fads and opinions. Along with models of epidemics, they constitute a major theoretical framework of social spreading processes. In threshold models on static networks, an individual changes her state if a certain fraction of her neighbors has done the same. When there are strong correlations in the temporal aspects of contact patterns, it is useful to represent the system as a temporal network. In such a system, not only contacts but also the time of the contacts are represented explicitly. In many cases, bursty temporal patterns slow down disease spreading. However, as we will see, this is not a universal truth for threshold models. In this work we propose an extension of Watts’s classic threshold model to temporal networks. We do this by assuming that an agent is influenced by contacts which lie a certain time into the past. I.e., the individuals are affected by contacts within a time window. In addition to thresholds in the fraction of contacts, we also investigate the number of contacts within the time window as a basis for influence. To elucidate the model’s behavior, we run the model on real and randomized empirical contact datasets.

  2. Setting conservation management thresholds using a novel participatory modeling approach.

    Science.gov (United States)

    Addison, P F E; de Bie, K; Rumpff, L

    2015-10-01

    We devised a participatory modeling approach for setting management thresholds that show when management intervention is required to address undesirable ecosystem changes. This approach was designed to be used when management thresholds: must be set for environmental indicators in the face of multiple competing objectives; need to incorporate scientific understanding and value judgments; and will be set by participants with limited modeling experience. We applied our approach to a case study where management thresholds were set for a mat-forming brown alga, Hormosira banksii, in a protected area management context. Participants, including management staff and scientists, were involved in a workshop to test the approach, and set management thresholds to address the threat of trampling by visitors to an intertidal rocky reef. The approach involved trading off the environmental objective, to maintain the condition of intertidal reef communities, with social and economic objectives to ensure management intervention was cost-effective. Ecological scenarios, developed using scenario planning, were a key feature that provided the foundation for where to set management thresholds. The scenarios developed represented declines in percent cover of H. banksii that may occur under increased threatening processes. Participants defined 4 discrete management alternatives to address the threat of trampling and estimated the effect of these alternatives on the objectives under each ecological scenario. A weighted additive model was used to aggregate participants' consequence estimates. Model outputs (decision scores) clearly expressed uncertainty, which can be considered by decision makers and used to inform where to set management thresholds. This approach encourages a proactive form of conservation, where management thresholds and associated actions are defined a priori for ecological indicators, rather than reacting to unexpected ecosystem changes in the future. © 2015 The

  3. Optical Associative Memory Model With Threshold Modification Using Complementary Vector

    Science.gov (United States)

    Bian, Shaoping; Xu, Kebin; Hong, Jing

    1989-02-01

    A new criterion to evaluate the similarity between two vectors in associative memory is presented. According to it, an experimental research about optical associative memory model with threshold modification using complementary vector is carried out. This model is capable of eliminating the posibility to recall erroneously. Therefore the accuracy of reading out is improved.

  4. Empirical assessment of a threshold model for sylvatic plague

    DEFF Research Database (Denmark)

    Davis, Stephen; Leirs, Herwig; Viljugrein, H.

    2007-01-01

    Plague surveillance programmes established in Kazakhstan, Central Asia, during the previous century, have generated large plague archives that have been used to parameterize an abundance threshold model for sylvatic plague in great gerbil (Rhombomys opimus) populations. Here, we assess the model...... examine six hypotheses that could explain the resulting false positive predictions, namely (i) including end-of-outbreak data erroneously lowers the estimated threshold, (ii) too few gerbils were tested, (iii) plague becomes locally extinct, (iv) the abundance of fleas was too low, (v) the climate...

  5. The multifactorial role of the 3Rs in shifting the harm-benefit analysis in animal models of disease

    Science.gov (United States)

    Graham, Melanie L.; Prescott, Mark J.

    2015-01-01

    Ethics on animal use in science in Western society is based on utilitarianism, weighing the harms and benefits to the animals involved against those of the intended human beneficiaries. The 3Rs concept (Replacement, Reduction, Refinement) is both a robust framework for minimizing animal use and suffering (addressing the harms to animals) and a means of supporting high quality science and translation (addressing the benefits). The ambiguity of basic research performed early in the research continuum can sometimes make harm-benefit analysis more difficult since anticipated benefit is often an incremental contribution to a field of knowledge. On the other hand, benefit is much more evident in translational research aimed at developing treatments for direct application in humans or animals suffering from disease. Though benefit may be easier to define, it should certainly not be considered automatic. Issues related to model validity seriously compromise experiments and have been implicated as a major impediment in translation, especially in complex disease models where harms to animals can be intensified. Increased investment and activity in the 3Rs is delivering new research models, tools and approaches with reduced reliance on animal use, improved animal welfare, and improved scientific and predictive value. PMID:25823812

  6. [The PROPRESE trial: results of a new health care organizational model in primary care for patients with chronic coronary heart disease based on a multifactorial intervention].

    Science.gov (United States)

    Ruescas-Escolano, Esther; Orozco-Beltran, Domingo; Gaubert-Tortosa, María; Navarro-Palazón, Ana; Cordero-Fort, Alberto; Navarro-Pérez, Jorge; Carratalá-Munuera, Concepción; Pertusa-Martínez, Salvador; Soler-Bahilo, Enrique; Brotons-Muntó, Francisco; Bort-Cubero, Jose; Núñez-Martínez, Miguel A; Bertomeu-Martínez, Vicente; López-Pineda, Adriana; Gil-Guillén, Vicente F

    2014-06-01

    Comparison of the results from the EUROASPIRE I to the EUROASPIRE III, in patients with coronary heart disease, shows that the prevalence of uncontrolled risk factors remains high. The aim of the study was to evaluate the effectiveness of a new multifactorial intervention in order to improve health care for chronic coronary heart disease patients in primary care. In this randomized clinical trial with a 1-year follow-up period, we recruited patients with a diagnosis of coronary heart disease (145 for the intervention group and 1461 for the control group). An organizational intervention on the patient-professional relationship (centered on the Chronic Care Model, the Stanford Expert Patient Programme and the Kaiser Permanente model) and formative strategy for professionals were carried out. The main outcomes were smoking control, low-density lipoprotein cholesterol (LDL-C), systolic blood pressure (SBP) and diastolic blood pressure (DBP). A multivariate analysis was performed. The characteristics of patients were: age (68.4±11.8 years), male (71.6%), having diabetes mellitus (51.3%), dyslipidemia (68.5%), arterial hypertension (76.7%), non-smokers (76.1%); LDL-C cardiovascular risk factors control (smoking, LDL-C and SBP). Chronic care strategies may be an efficacy tool to help clinicians to involve the patients with a diagnosis of CHD to reach better outcomes. Copyright © 2014 Elsevier España, S.L. All rights reserved.

  7. Extinction threshold of a population in spatial and stochastic model

    OpenAIRE

    Soroka, Yevheniia; Rublyov, Bogdan

    2016-01-01

    In this study, spatial stochastic and logistic model (SSLM) describing dynamics of a population of a certain species was analysed. The behaviour of the extinction threshold as a function of model parameters was studied. More specifically, we studied how the critical values for the model parameters that separate the cases of extinction and persistence depend on the spatial scales of the competition and dispersal kernels. We compared the simulations and analytical results to examine if and how ...

  8. Nanoethosomes for transdermal delivery of tropisetron HCl: multi-factorial predictive modeling, characterization, and ex vivo skin permeation.

    Science.gov (United States)

    Abdel Messih, Hanaa A; Ishak, Rania A H; Geneidi, Ahmed S; Mansour, Samar

    2017-06-01

    The aim of the present work is to exclusively optimize and model the effect of phospholipid type either egg phosphatidylcholine (EPC) or soybean phosphatidylcholine (SPC), together with other formulation variables, on the development of nano-ethosomal systems for transdermal delivery of a water-soluble antiemetic drug. Tropisetron HCl (TRO) is available as hard gelatin capsules and IV injections. The transdermal delivery of TRO is considered as a novel alternative route supposing to improve BAV as well as patient convenience. TRO-loaded ethanolic vesicular systems were prepared by hot technique. The effect of formulation variables were optimized through a response surface methodology using 3 × 2 2 -level full factorial design. The concentrations of both PC (A) and ethanol (B) and PC type (C) were the factors, while entrapment efficiency (Y 1 ), vesicle size (Y 2 ), polydispersity index (Y 3 ), and zeta potential (Y 4 ) were the responses. The drug permeation across rat skin from selected formulae was studied. Particle morphology, drug-excipient interactions, and vesicle stability were also investigated. The results proved the critical role of all formulation variables on ethosomal characteristics. The suggested models for all responses showed good predictability. Only the concentration of phospholipid, irrespective to PC type, had a significant effect on the transdermal flux (p transdermal TRO delivery.

  9. The threshold of a stochastic SIQS epidemic model

    Science.gov (United States)

    Zhang, Xiao-Bing; Huo, Hai-Feng; Xiang, Hong; Shi, Qihong; Li, Dungang

    2017-09-01

    In this paper, we present the threshold of a stochastic SIQS epidemic model which determines the extinction and persistence of the disease. Furthermore, we find that noise can suppress the disease outbreak. Numerical simulations are also carried out to confirm the analytical results.

  10. Stochasticity thresholds in the Fermi-Pasta-Ulam model

    International Nuclear Information System (INIS)

    Callegari, B.; Galgani, L.; Milan Univ.

    1979-01-01

    The authors consider the celebrated model of Fermi, Pasta and Ulam and give a numerical estimate for its thresholds of stochasticity, thus determining a critical energy as a function of the frequency of the corresponding oscillators. The results turn out to be qualitatively similar to those already obtained for a chain of particles with nearest-neighbour Lennard-Jones interaction potential. (author)

  11. Stochasticity thresholds in the Fermi-Pasta-Ulam model

    Energy Technology Data Exchange (ETDEWEB)

    Callegari, B [Ferrara Univ. (Italy). Ist. di Matematica; Carotta, M C; Ferrario, C [Ferrara Univ. (Italy). Ist. di Fisica; Lo Vecchio, G [Ferrara Univ. (Italy). Ist. di Fisica; Gruppo Nazionale di Struttura della Materia, Ferrara (Italy)); Galgani, L [Milan Univ. (Italy). Ist. di Fisica; Milan Univ. (Italy). Ist. di Matematica)

    1979-12-11

    The authors consider the celebrated model of Fermi, Pasta and Ulam and give a numerical estimate for its thresholds of stochasticity, thus determining a critical energy as a function of the frequency of the corresponding oscillators. The results turn out to be qualitatively similar to those already obtained for a chain of particles with nearest-neighbour Lennard-Jones interaction potential.

  12. [Polygenic threshold model and the phenogenetic aspects of human fingerprints].

    Science.gov (United States)

    Voĭtenko, V P; Poliukhov, A M

    1981-01-01

    Based on the existence of the two genetic complexes determining finger prints (SU - spiral and SR - despiral), the two-compartment multithreshold polygenic model for systematization of finger prints has been proposed. It was found that the radial loop is genotypically not identical to the ulnar loop, as it was thought before, but differs very much from the latter by its print. The relative height of thresholds for each of 10 fingers has been measured. The two embryonal gradients have been established: one with a positive, and the other with a negative correlation between the threshold heights.

  13. Algorithmic detectability threshold of the stochastic block model

    Science.gov (United States)

    Kawamoto, Tatsuro

    2018-03-01

    The assumption that the values of model parameters are known or correctly learned, i.e., the Nishimori condition, is one of the requirements for the detectability analysis of the stochastic block model in statistical inference. In practice, however, there is no example demonstrating that we can know the model parameters beforehand, and there is no guarantee that the model parameters can be learned accurately. In this study, we consider the expectation-maximization (EM) algorithm with belief propagation (BP) and derive its algorithmic detectability threshold. Our analysis is not restricted to the community structure but includes general modular structures. Because the algorithm cannot always learn the planted model parameters correctly, the algorithmic detectability threshold is qualitatively different from the one with the Nishimori condition.

  14. Threshold corrections and gauge symmetry in twisted superstring models

    International Nuclear Information System (INIS)

    Pierce, D.M.

    1994-01-01

    Threshold corrections to the running of gauge couplings are calculated for superstring models with free complex world sheet fermions. For two N=1 SU(2)xU(1) 5 models, the threshold corrections lead to a small increase in the unification scale. Examples are given to illustrate how a given particle spectrum can be described by models with different boundary conditions on the internal fermions. We also discuss how complex twisted fermions can enhance the symmetry group of an N=4, SU(3)xU(1)xU(1) model to the gauge group SU(3)xSU(2)xU(1). It is then shown how a mixing angle analogous to the Weinberg angle depends on the boundary conditions of the internal fermions

  15. On the renewal risk model under a threshold strategy

    Science.gov (United States)

    Dong, Yinghui; Wang, Guojing; Yuen, Kam C.

    2009-08-01

    In this paper, we consider the renewal risk process under a threshold dividend payment strategy. For this model, the expected discounted dividend payments and the Gerber-Shiu expected discounted penalty function are investigated. Integral equations, integro-differential equations and some closed form expressions for them are derived. When the claims are exponentially distributed, it is verified that the expected penalty of the deficit at ruin is proportional to the ruin probability.

  16. Selection Strategies for Social Influence in the Threshold Model

    Science.gov (United States)

    Karampourniotis, Panagiotis; Szymanski, Boleslaw; Korniss, Gyorgy

    The ubiquity of online social networks makes the study of social influence extremely significant for its applications to marketing, politics and security. Maximizing the spread of influence by strategically selecting nodes as initiators of a new opinion or trend is a challenging problem. We study the performance of various strategies for selection of large fractions of initiators on a classical social influence model, the Threshold model (TM). Under the TM, a node adopts a new opinion only when the fraction of its first neighbors possessing that opinion exceeds a pre-assigned threshold. The strategies we study are of two kinds: strategies based solely on the initial network structure (Degree-rank, Dominating Sets, PageRank etc.) and strategies that take into account the change of the states of the nodes during the evolution of the cascade, e.g. the greedy algorithm. We find that the performance of these strategies depends largely on both the network structure properties, e.g. the assortativity, and the distribution of the thresholds assigned to the nodes. We conclude that the optimal strategy needs to combine the network specifics and the model specific parameters to identify the most influential spreaders. Supported in part by ARL NS-CTA, ARO, and ONR.

  17. A threshold model for Australian Stock Exchange equities

    Science.gov (United States)

    Bertram, William K.

    2005-02-01

    In this paper, we present a threshold model to describe the phenomena of zero return enhancement that is present in Australian Stock Exchange data. We examine the intraday behaviour of the ASX data and construct a new measure for the market activity using principal component analysis. We use this measure to create a business time scale that keeps the level of zero return enhancement constant throughout trading hours. Operating in this new time scale we fit the model to data for small and large time scales and find that the model affords an excellent approximation of the distribution of stock returns.

  18. The liability threshold model for censored twin data

    DEFF Research Database (Denmark)

    Holst, Klaus K.; Scheike, Thomas; Hjelmborg, Jacob B.

    2016-01-01

    the disease thus still being at risk. Ignoring this right-censoring can lead to severely biased estimates. The classical liability threshold model can be extended with inverse probability of censoring weighting of complete observations. This leads to a flexible way of modelling twin concordance and obtaining...... studies of diseases, as a way of quantifying such genetic contribution. The endpoint in these studies are typically defined as occurrence of a disease versus death without the disease. However, a large fraction of the subjects may still be alive at the time of follow-up without having experienced...

  19. Sri Lankan FRAX model and country-specific intervention thresholds.

    Science.gov (United States)

    Lekamwasam, Sarath

    2013-01-01

    There is a wide variation in fracture probabilities estimated by Asian FRAX models, although the outputs of South Asian models are concordant. Clinicians can choose either fixed or age-specific intervention thresholds when making treatment decisions in postmenopausal women. Cost-effectiveness of such approach, however, needs to be addressed. This study examined suitable fracture probability intervention thresholds (ITs) for Sri Lanka, based on the Sri Lankan FRAX model. Fracture probabilities were estimated using all Asian FRAX models for a postmenopausal woman of BMI 25 kg/m² and has no clinical risk factors apart from a fragility fracture, and they were compared. Age-specific ITs were estimated based on the Sri Lankan FRAX model using the method followed by the National Osteoporosis Guideline Group in the UK. Using the age-specific ITs as the reference standard, suitable fixed ITs were also estimated. Fracture probabilities estimated by different Asian FRAX models varied widely. Japanese and Taiwan models showed higher fracture probabilities while Chinese, Philippine, and Indonesian models gave lower fracture probabilities. Output of remaining FRAX models were generally similar. Age-specific ITs of major osteoporotic fracture probabilities (MOFP) based on the Sri Lankan FRAX model varied from 2.6 to 18% between 50 and 90 years. ITs of hip fracture probabilities (HFP) varied from 0.4 to 6.5% between 50 and 90 years. In finding fixed ITs, MOFP of 11% and HFP of 3.5% gave the lowest misclassification and highest agreement. Sri Lankan FRAX model behaves similar to other Asian FRAX models such as Indian, Singapore-Indian, Thai, and South Korean. Clinicians may use either the fixed or age-specific ITs in making therapeutic decisions in postmenopausal women. The economical aspects of such decisions, however, need to be considered.

  20. Terrestrial Microgravity Model and Threshold Gravity Simulation using Magnetic Levitation

    Science.gov (United States)

    Ramachandran, N.

    2005-01-01

    What is the threshold gravity (minimum gravity level) required for the nominal functioning of the human system? What dosage is required? Do human cell lines behave differently in microgravity in response to an external stimulus? The critical need for such a gravity simulator is emphasized by recent experiments on human epithelial cells and lymphocytes on the Space Shuttle clearly showing that cell growth and function are markedly different from those observed terrestrially. Those differences are also dramatic between cells grown in space and those in Rotating Wall Vessels (RWV), or NASA bioreactor often used to simulate microgravity, indicating that although morphological growth patterns (three dimensional growth) can be successfully simulated using RWVs, cell function performance is not reproduced - a critical difference. If cell function is dramatically affected by gravity off-loading, then cell response to stimuli such as radiation, stress, etc. can be very different from terrestrial cell lines. Yet, we have no good gravity simulator for use in study of these phenomena. This represents a profound shortcoming for countermeasures research. We postulate that we can use magnetic levitation of cells and tissue, through the use of strong magnetic fields and field gradients, as a terrestrial microgravity model to study human cells. Specific objectives of the research are: 1. To develop a tried, tested and benchmarked terrestrial microgravity model for cell culture studies; 2. Gravity threshold determination; 3. Dosage (magnitude and duration) of g-level required for nominal functioning of cells; 4. Comparisons of magnetic levitation model to other models such as RWV, hind limb suspension, etc. and 5. Cellular response to reduced gravity levels of Moon and Mars. The paper will discuss experiments md modeling work to date in support of this project.

  1. Modeling strong-field above-threshold ionization

    International Nuclear Information System (INIS)

    Sundaram, B.; Armstrong, L. Jr.

    1990-01-01

    Above-threshold ionization (ATI) by intense, short-pulse lasers is studied numerically, using the stretched hydrogen atom Hamiltonian. Within our model system, we isolate several mechanisms that contribute to the ATI process. These mechanisms, which involve both excited bound states and continuum states, all invoke intermediate, off-energy shell transitions. In particular, the importance of excited bound states and off-energy shell bound-free processes to the ionization mechanism are shown to relate to a simple physical criterion. These processes point to importance differences in the interpretation of ionization characteristics for short pulses from that for longer pulses. Our analysis concludes that although components of ATI admit of simple, few-state modeling, the ultimate synthesis points to a highly complex mechanism

  2. Stylized facts from a threshold-based heterogeneous agent model

    Science.gov (United States)

    Cross, R.; Grinfeld, M.; Lamba, H.; Seaman, T.

    2007-05-01

    A class of heterogeneous agent models is investigated where investors switch trading position whenever their motivation to do so exceeds some critical threshold. These motivations can be psychological in nature or reflect behaviour suggested by the efficient market hypothesis (EMH). By introducing different propensities into a baseline model that displays EMH behaviour, one can attempt to isolate their effects upon the market dynamics. The simulation results indicate that the introduction of a herding propensity results in excess kurtosis and power-law decay consistent with those observed in actual return distributions, but not in significant long-term volatility correlations. Possible alternatives for introducing such long-term volatility correlations are then identified and discussed.

  3. Terrestrial Microgravity Model and Threshold Gravity Simulation sing Magnetic Levitation

    Science.gov (United States)

    Ramachandran, N.

    2005-01-01

    What is the threshold gravity (minimum gravity level) required for the nominal functioning of the human system? What dosage is required? Do human cell lines behave differently in microgravity in response to an external stimulus? The critical need for such a gravity simulator is emphasized by recent experiments on human epithelial cells and lymphocytes on the Space Shuttle clearly showing that cell growth and function are markedly different from those observed terrestrially. Those differences are also dramatic between cells grown in space and those in Rotating Wall Vessels (RWV), or NASA bioreactor often used to simulate microgravity, indicating that although morphological growth patterns (three dimensional growth) can be successiblly simulated using RWVs, cell function performance is not reproduced - a critical difference. If cell function is dramatically affected by gravity off-loading, then cell response to stimuli such as radiation, stress, etc. can be very different from terrestrial cell lines. Yet, we have no good gravity simulator for use in study of these phenomena. This represents a profound shortcoming for countermeasures research. We postulate that we can use magnetic levitation of cells and tissue, through the use of strong magnetic fields and field gradients, as a terrestrial microgravity model to study human cells. Specific objectives of the research are: 1. To develop a tried, tested and benchmarked terrestrial microgravity model for cell culture studies; 2. Gravity threshold determination; 3. Dosage (magnitude and duration) of g-level required for nominal functioning of cells; 4. Comparisons of magnetic levitation model to other models such as RWV, hind limb suspension, etc. and 5. Cellular response to reduced gravity levels of Moon and Mars.

  4. String Threshold corrections in models with spondaneously broken supersymmetry

    CERN Document Server

    Kiritsis, Elias B; Petropoulos, P M; Rizos, J

    1999-01-01

    We analyse a class of four-dimensional heterotic ground states with N=2 space-time supersymmetry. From the ten-dimensional perspective, such models can be viewed as compactifications on a six-dimensional manifold with SU(2) holonomy, which is locally but not globally K3 x T^2. The maximal N=4 supersymmetry is spontaneously broken to N=2. The masses of the two massive gravitinos depend on the (T,U) moduli of T^2. We evaluate the one-loop threshold corrections of gauge and R^2 couplings and we show that they fall in several universality classes, in contrast to what happens in usual K3 x T^2 compactifications, where the N=4 supersymmetry is explicitly broken to N=2, and where a single universality class appears. These universality properties follow from the structure of the elliptic genus. The behaviour of the threshold corrections as functions of the moduli is analysed in detail: it is singular across several rational lines of the T^2 moduli because of the appearance of extra massless states, and suffers only f...

  5. Applying threshold models to donations to a green electricity fund

    International Nuclear Information System (INIS)

    Ito, Nobuyuki; Takeuchi, Kenji; Tsuge, Takahiro; Kishimoto, Atsuo

    2010-01-01

    This study applies a threshold model proposed by to analyze the diffusion process of donating behavior for renewable energy. We first use a stated preference survey to estimate the determinants of a decision to support the donation scheme under various predicted participation rates. Using the estimated coefficients, we simulate how herd behavior spreads and the participation rate reaches the equilibrium. The participation rate at the equilibrium is estimated as 37.88% when the suggested donation is 500 yen, while it is 17.76% when the suggested amount is 1000 yen. The influence of environmentalism and altruism is also examined, and we find that these motivations increase the participation rate by 31.51% on average.

  6. How to detect and visualize extinction thresholds for structured PVA models

    NARCIS (Netherlands)

    Hildenbrandt, H.; Grimm, V.

    2006-01-01

    An extinction threshold is a population size below which extinction risk increases to beyond critical values. However, detecting extinction thresholds for structured population models is not straightforward because many different population structures may correspond to the same population size.

  7. Analytical drift-current threshold voltage model of long-channel double-gate MOSFETs

    International Nuclear Information System (INIS)

    Shih, Chun-Hsing; Wang, Jhong-Sheng

    2009-01-01

    This paper presents a new, physical threshold voltage model to solve the ambiguity in determining the threshold voltage of double-gate (DG) MOSFETs. To avoid the difficulties of the conventional 2ψ B model in nearly undoped DG MOSFETs, this study proposes to define the on–off switching based on the actual roles of the drift and diffusion components in the total drain current. The drift current strongly enhances beyond the threshold voltage, while the diffusion current plays a major role in the subthreshold. The threshold voltage is defined as the drift component that exceeds the diffusion counterpart. From the solutions of Poisson's equation, the drift and diffusion currents of DG MOSFETs are separately formulated to derive the analytical expressions of the threshold voltage and associated threshold current. This model provides a comprehensive description of the switching behavior of DG MOSFET devices, and offers a physical onset threshold current to determine the threshold voltage in practical extraction

  8. Thermalization threshold in models of 1D fermions

    Science.gov (United States)

    Mukerjee, Subroto; Modak, Ranjan; Ramswamy, Sriram

    2013-03-01

    The question of how isolated quantum systems thermalize is an interesting and open one. In this study we equate thermalization with non-integrability to try to answer this question. In particular, we study the effect of system size on the integrability of 1D systems of interacting fermions on a lattice. We find that for a finite-sized system, a non-zero value of an integrability breaking parameter is required to make an integrable system appear non-integrable. Using exact diagonalization and diagnostics such as energy level statistics and the Drude weight, we find that the threshold value of the integrability breaking parameter scales to zero as a power law with system size. We find the exponent to be the same for different models with its value depending on the random matrix ensemble describing the non-integrable system. We also study a simple analytical model of a non-integrable system with an integrable limit to better understand how a power law emerges.

  9. Modeling of Auditory Neuron Response Thresholds with Cochlear Implants

    Directory of Open Access Journals (Sweden)

    Frederic Venail

    2015-01-01

    Full Text Available The quality of the prosthetic-neural interface is a critical point for cochlear implant efficiency. It depends not only on technical and anatomical factors such as electrode position into the cochlea (depth and scalar placement, electrode impedance, and distance between the electrode and the stimulated auditory neurons, but also on the number of functional auditory neurons. The efficiency of electrical stimulation can be assessed by the measurement of e-CAP in cochlear implant users. In the present study, we modeled the activation of auditory neurons in cochlear implant recipients (nucleus device. The electrical response, measured using auto-NRT (neural responses telemetry algorithm, has been analyzed using multivariate regression with cubic splines in order to take into account the variations of insertion depth of electrodes amongst subjects as well as the other technical and anatomical factors listed above. NRT thresholds depend on the electrode squared impedance (β = −0.11 ± 0.02, P<0.01, the scalar placement of the electrodes (β = −8.50 ± 1.97, P<0.01, and the depth of insertion calculated as the characteristic frequency of auditory neurons (CNF. Distribution of NRT residues according to CNF could provide a proxy of auditory neurons functioning in implanted cochleas.

  10. Threshold models of recognition and the recognition heuristic

    Directory of Open Access Journals (Sweden)

    Edgar Erdfelder

    2011-02-01

    Full Text Available According to the recognition heuristic (RH theory, decisions follow the recognition principle: Given a high validity of the recognition cue, people should prefer recognized choice options compared to unrecognized ones. Assuming that the memory strength of choice options is strongly correlated with both the choice criterion and recognition judgments, the RH is a reasonable strategy that approximates optimal decisions with a minimum of cognitive effort (Davis-Stober, Dana, and Budescu, 2010. However, theories of recognition memory are not generally compatible with this assumption. For example, some threshold models of recognition presume that recognition judgments can arise from two types of cognitive states: (1 certainty states in which judgments are almost perfectly correlated with memory strength and (2 uncertainty states in which recognition judgments reflect guessing rather than differences in memory strength. We report an experiment designed to test the prediction that the RH applies to certainty states only. Our results show that memory states rather than recognition judgments affect use of recognition information in binary decisions.

  11. Diverging strains near threshold: Breakdown of the elastic description of a charge density wave model

    International Nuclear Information System (INIS)

    Mungan, M.; Coppersmith, S.; Vinokur, V.M.

    1999-01-01

    We analyze the strains near threshold in 1-d charge density wave models at zero temperature and strong pinning. We show that in these models local strains diverge near the depinning threshold and characterize the scaling behavior of the phenomenon. This helps quantify when the underlying elastic description breaks down and plastic effects have to be included

  12. Modelo predictivo del espesor de la capa de óxido y microdureza en aluminio Al3003-B14 y Al6063-T6 anodizado usando análisis multifactorial Oxide film thickness and microhardness prediction model of Al3003-B14 and Al6063-T6 anodized aluminum using multifactorial analysis

    Directory of Open Access Journals (Sweden)

    Leonardo Eladio Vergara Guillén

    2011-08-01

    Full Text Available En esta investigación se modela a partir de los parámetros del proceso el espesor de la capa de óxido y la microdureza de los aluminios Al3003 y Al6063 anodizados. Para ello se realizaron estudios de la microdureza y espesor de capa de la superficie anodizada, utilizando técnicas de análisis multifactorial y diseño robusto. Se establecieron los siguientes niveles de los parámetros del proceso: temperatura [15 °C, 25 °C], tiempo [30 min; 60 min], concentración de electrolito [1,2 M; 2 M], densidad de corriente [1 Amp/dm²; 3 Amp/dm²], aluminio [Al3003,Al6063] y como variable de ruido, la deformación plástica [0%, 10%, 20%, 30%]. Se propuso un diseño fraccionado 2(7-2 mixto, con el cual se efectuó un total de 48 pruebas usando soluciones electrolíticas de ácido sulfúrico. La medición de microdureza se realizó con un indentador Vickers con carga de 400 g; el espesor de la capa de óxido se captó mediante microscopia electrónica. A los resultados se les realizó un análisis de varianza (ANOVA, para determinar los factores significativos y la robustez de los efectos. Se encontraron resultados de microdureza [HV] [85,74-308,87]; y espesor de óxido [µm] [12,82- 94,69]. Finalmente, se muestran los modelos de predicción de cada una de las respuestas en función de los factores significativos estas ecuaciones permitirán seleccionar la microdureza y espesor de la capa de óxido para cumplir los requerimientos de un producto particular mediante una selección apropiada de los parámetros del proceso.In this research, the thickness of the oxide layer and the microhardness of anodized aluminum Al3003 and Al6063 are modeled based on process parameters. To this end, studies of the microhardness and the thickness layer of the anodized surface were made, via techniques of multifactorial analysis and robust design. The following levels of the process parameters were established: temperature [15°C, 25°C], time [30min; 60min

  13. A Combinatorics Proliferation Model with Threshold for Malware Countermeasure

    OpenAIRE

    Omote, Kazumasa; Shimoyama, Takeshi; Torii, Satoru

    2010-01-01

    Security software such as anti-virus software and personal firewall are usually installed in every host within an enterprise network. There are mainly two kinds of security software: signature-based software and anomaly-based software. Anomaly-based software generally has a “threshold” that discriminates between normal traffic and malware communications in network traffic observation. Such a threshold involves the number of packets used for behavior checking by the anomaly-based software. Als...

  14. Threshold Dynamics of a Stochastic Chemostat Model with Two Nutrients and One Microorganism

    Directory of Open Access Journals (Sweden)

    Jian Zhang

    2017-01-01

    Full Text Available A new stochastic chemostat model with two substitutable nutrients and one microorganism is proposed and investigated. Firstly, for the corresponding deterministic model, the threshold for extinction and permanence of the microorganism is obtained by analyzing the stability of the equilibria. Then, for the stochastic model, the threshold of the stochastic chemostat for extinction and permanence of the microorganism is explored. Difference of the threshold of the deterministic model and the stochastic model shows that a large stochastic disturbance can affect the persistence of the microorganism and is harmful to the cultivation of the microorganism. To illustrate this phenomenon, we give some computer simulations with different intensity of stochastic noise disturbance.

  15. Hydrodynamic modeling and simulations of shock ignition thresholds

    Directory of Open Access Journals (Sweden)

    Lafon M.

    2013-11-01

    Full Text Available The Shock Ignition (SI scheme [1] offers to reduce the laser requirements by relaxing the implosion phase to sub-ignition velocities and later adding an intense laser spike. Depending on laser energy, target characteristics and implosion velocity, high gains are expected [2,3]. Relevant intensities for scaled targets imploded in the velocity range from 150 to 400 km/s are defined at ignition thresholds. A range of moderate implosion velocities is specified to match safe implosions. These conditions for target design are then inferred for relevant NIF and LMJ shock-ignited targets.

  16. The Threshold of a Stochastic SIRS Model with Vertical Transmission and Saturated Incidence

    Directory of Open Access Journals (Sweden)

    Chunjuan Zhu

    2017-01-01

    Full Text Available The threshold of a stochastic SIRS model with vertical transmission and saturated incidence is investigated. If the noise is small, it is shown that the threshold of the stochastic system determines the extinction and persistence of the epidemic. In addition, we find that if the noise is large, the epidemic still prevails. Finally, numerical simulations are given to illustrate the results.

  17. Modelling the regulatory system for diabetes mellitus with a threshold window

    Science.gov (United States)

    Yang, Jin; Tang, Sanyi; Cheke, Robert A.

    2015-05-01

    Piecewise (or non-smooth) glucose-insulin models with threshold windows for type 1 and type 2 diabetes mellitus are proposed and analyzed with a view to improving understanding of the glucose-insulin regulatory system. For glucose-insulin models with a single threshold, the existence and stability of regular, virtual, pseudo-equilibria and tangent points are addressed. Then the relations between regular equilibria and a pseudo-equilibrium are studied. Furthermore, the sufficient and necessary conditions for the global stability of regular equilibria and the pseudo-equilibrium are provided by using qualitative analysis techniques of non-smooth Filippov dynamic systems. Sliding bifurcations related to boundary node bifurcations were investigated with theoretical and numerical techniques, and insulin clinical therapies are discussed. For glucose-insulin models with a threshold window, the effects of glucose thresholds or the widths of threshold windows on the durations of insulin therapy and glucose infusion were addressed. The duration of the effects of an insulin injection is sensitive to the variation of thresholds. Our results indicate that blood glucose level can be maintained within a normal range using piecewise glucose-insulin models with a single threshold or a threshold window. Moreover, our findings suggest that it is critical to individualise insulin therapy for each patient separately, based on initial blood glucose levels.

  18. A Threshold Model of Social Support, Adjustment, and Distress after Breast Cancer Treatment

    Science.gov (United States)

    Mallinckrodt, Brent; Armer, Jane M.; Heppner, P. Paul

    2012-01-01

    This study examined a threshold model that proposes that social support exhibits a curvilinear association with adjustment and distress, such that support in excess of a critical threshold level has decreasing incremental benefits. Women diagnosed with a first occurrence of breast cancer (N = 154) completed survey measures of perceived support…

  19. Threshold burnup for recrystallization and model for rim porosity in the high burnup UO2 fuel

    International Nuclear Information System (INIS)

    Lee, Byung Ho; Koo, Yang Hyun; Sohn, Dong Seong

    1998-01-01

    Applicability of the threshold burnup for rim formation was investigated as a function of temperature by Rest's model. The threshold burnup was the lowest in the intermediate temperature region, while on the other temperature regions the threshold burnup is higher. The rim porosity was predicted by the van der Waals equation based of the rim pore radius of 0.75μm and the overpressurization model on rim pores. The calculated centerline temperature is in good agreement with the measured temperature. However, more efforts seem to be necessary for the mechanistic model of the rim effect including rim growth with the fuel burnup

  20. A phenomenological model on the kink mode threshold varying with the inclination of sheath boundary

    International Nuclear Information System (INIS)

    Sun, X.; Intrator, T. P.; Sears, J.; Weber, T.; Liu, M.

    2013-01-01

    In nature and many laboratory plasmas, a magnetic flux tube threaded by current or a flux rope has a footpoint at a boundary. The current driven kink mode is one of the fundamental ideal magnetohydrodynamic instabilities in plasmas. It has an instability threshold that has been found to strongly depend on boundary conditions (BCs). We provide a theoretical model to explain the transition of this threshold dependence between nonline tied and line tied boundary conditions. We evaluate model parameters using experimentally measured plasma data, explicitly verify several kink eigenfunctions, and validate the model predictions for boundary conditions BCs that span the range between NLT and LT BCs. Based on this model, one could estimate the kink threshold given knowledge of the displacement of a flux rope end, or conversely estimate flux rope end motion based on knowledge of it kink stability threshold

  1. The threshold of a stochastic delayed SIR epidemic model with vaccination

    Science.gov (United States)

    Liu, Qun; Jiang, Daqing

    2016-11-01

    In this paper, we study the threshold dynamics of a stochastic delayed SIR epidemic model with vaccination. We obtain sufficient conditions for extinction and persistence in the mean of the epidemic. The threshold between persistence in the mean and extinction of the stochastic system is also obtained. Compared with the corresponding deterministic model, the threshold affected by the white noise is smaller than the basic reproduction number Rbar0 of the deterministic system. Results show that time delay has important effects on the persistence and extinction of the epidemic.

  2. The threshold of a stochastic delayed SIR epidemic model with temporary immunity

    Science.gov (United States)

    Liu, Qun; Chen, Qingmei; Jiang, Daqing

    2016-05-01

    This paper is concerned with the asymptotic properties of a stochastic delayed SIR epidemic model with temporary immunity. Sufficient conditions for extinction and persistence in the mean of the epidemic are established. The threshold between persistence in the mean and extinction of the epidemic is obtained. Compared with the corresponding deterministic model, the threshold affected by the white noise is smaller than the basic reproduction number R0 of the deterministic system.

  3. Statistical modeling of competitive threshold collision-induced dissociation

    Science.gov (United States)

    Rodgers, M. T.; Armentrout, P. B.

    1998-08-01

    Collision-induced dissociation of (R1OH)Li+(R2OH) with xenon is studied using guided ion beam mass spectrometry. R1OH and R2OH include the following molecules: water, methanol, ethanol, 1-propanol, 2-propanol, and 1-butanol. In all cases, the primary products formed correspond to endothermic loss of one of the neutral alcohols, with minor products that include those formed by ligand exchange and loss of both ligands. The cross-section thresholds are interpreted to yield 0 and 298 K bond energies for (R1OH)Li+-R2OH and relative Li+ binding affinities of the R1OH and R2OH ligands after accounting for the effects of multiple ion-molecule collisions, internal energy of the reactant ions, and dissociation lifetimes. We introduce a means to simultaneously analyze the cross sections for these competitive dissociations using statistical theories to predict the energy dependent branching ratio. Thermochemistry in good agreement with previous work is obtained in all cases. In essence, this statistical approach provides a detailed means of correcting for the "competitive shift" inherent in multichannel processes.

  4. The threshold bias model: a mathematical model for the nomothetic approach of suicide.

    Science.gov (United States)

    Folly, Walter Sydney Dutra

    2011-01-01

    Comparative and predictive analyses of suicide data from different countries are difficult to perform due to varying approaches and the lack of comparative parameters. A simple model (the Threshold Bias Model) was tested for comparative and predictive analyses of suicide rates by age. The model comprises of a six parameter distribution that was applied to the USA suicide rates by age for the years 2001 and 2002. Posteriorly, linear extrapolations are performed of the parameter values previously obtained for these years in order to estimate the values corresponding to the year 2003. The calculated distributions agreed reasonably well with the aggregate data. The model was also used to determine the age above which suicide rates become statistically observable in USA, Brazil and Sri Lanka. The Threshold Bias Model has considerable potential applications in demographic studies of suicide. Moreover, since the model can be used to predict the evolution of suicide rates based on information extracted from past data, it will be of great interest to suicidologists and other researchers in the field of mental health.

  5. Threshold voltage roll-off modelling of bilayer graphene field-effect transistors

    International Nuclear Information System (INIS)

    Saeidmanesh, M; Ismail, Razali; Khaledian, M; Karimi, H; Akbari, E

    2013-01-01

    An analytical model is presented for threshold voltage roll-off of double gate bilayer graphene field-effect transistors. To this end, threshold voltage models of short- and long-channel states have been developed. In the short-channel case, front and back gate potential distributions have been modelled and used. In addition, the tunnelling probability is modelled and its effect is taken into consideration in the potential distribution model. To evaluate the accuracy of the potential model, FlexPDE software is employed with proper boundary conditions and a good agreement is observed. Using the proposed models, the effect of several structural parameters on the threshold voltage and its roll-off are studied at room temperature. (paper)

  6. Shifting physician prescribing to a preferred histamine-2-receptor antagonist. Effects of a multifactorial intervention in a mixed-model health maintenance organization.

    Science.gov (United States)

    Brufsky, J W; Ross-Degnan, D; Calabrese, D; Gao, X; Soumerai, S B

    1998-03-01

    This study was undertaken to determine whether a program of education, therapeutic reevaluation of eligible patients, and performance feedback could shift prescribing to cimetidine from other histamine-2 receptor antagonists, which commonly are used in the management of ulcers and reflux, and reduce costs without increasing rates of ulcer-related hospital admissions. This study used an interrupted monthly time series with comparison series in a large mixed-model health maintenance organization. Physicians employed in health centers (staff model) and physicians in independent medical groups contracting to provide health maintenance organization services (group model) participated. The comparative percentage prescribed of specific histamine-2 receptor antagonists (market share), total histamine-2 receptor antagonist prescribing, cost per histamine-2 receptor antagonist prescription, and the rate of hospitalization for gastrointestinal illness were assessed. In the staff model, therapeutic reevaluation resulted in a sudden increase in market share of the preferred histamine-2 receptor antagonist cimetidine (+53.8%) and a sudden decrease in ranitidine (-44.7%) and famotidine (-4.8%); subsequently, cimetidine market share grew by 1.1% per month. In the group model, therapeutic reevaluation resulted in increased cimetidine market share (+9.7%) and decreased prescribing of other histamine-2 receptor antagonists (ranitidine -11.6%; famotidine -1.2%). Performance feedback did not result in further changes in prescribing in either setting. Use of omeprazole, an expensive alternative, essentially was unchanged by the interventions, as were overall histamine-2 receptor antagonist prescribing and hospital admissions for gastrointestinal illnesses. This intervention, which cost approximately $60,000 to implement, resulted in estimated annual savings in histamine-2 receptor antagonist expenditures of $1.06 million. Annual savings in histamine-2 receptor antagonist expenditures

  7. A generalized methodology for identification of threshold for HRU delineation in SWAT model

    Science.gov (United States)

    M, J.; Sudheer, K.; Chaubey, I.; Raj, C.

    2016-12-01

    The distributed hydrological model, Soil and Water Assessment Tool (SWAT) is a comprehensive hydrologic model widely used for making various decisions. The simulation accuracy of the distributed hydrological model differs due to the mechanism involved in the subdivision of the watershed. Soil and Water Assessment Tool (SWAT) considers sub-dividing the watershed and the sub-basins into small computing units known as 'hydrologic response units (HRU). The delineation of HRU is done based on unique combinations of land use, soil types, and slope within the sub-watersheds, which are not spatially defined. The computations in SWAT are done at HRU level and are then aggregated up to the sub-basin outlet, which is routed through the stream system. Generally, the HRUs are delineated by considering a threshold percentage of land use, soil and slope are to be given by the modeler to decrease the computation time of the model. The thresholds constrain the minimum area for constructing an HRU. In the current HRU delineation practice in SWAT, the land use, soil and slope of the watershed within a sub-basin, which is less than the predefined threshold, will be surpassed by the dominating land use, soil and slope, and introduce some level of ambiguity in the process simulations in terms of inappropriate representation of the area. But the loss of information due to variation in the threshold values depends highly on the purpose of the study. Therefore this research studies the effects of threshold values of HRU delineation on the hydrological modeling of SWAT on sediment simulations and suggests guidelines for selecting the appropriate threshold values considering the sediment simulation accuracy. The preliminary study was done on Illinois watershed by assigning different thresholds for land use and soil. A general methodology was proposed for identifying an appropriate threshold for HRU delineation in SWAT model that considered computational time and accuracy of the simulation

  8. Threshold pion photoproduction in A light-cone quark model

    International Nuclear Information System (INIS)

    Konen, W.; Drechsel, D.

    1991-01-01

    The instantaneous and seagull graphs are calculated for pion photoproduction in a relativistic light-cone model of the nucleon. In both pseudoscalar and pseudovector coupling we find the ratios A (-) :A (0) :A (+) =1:(-1/2μ):(-9/5 1/2μ) in the nonrelativistic limit. These results correspond to the sum of seagull and Z-graph in the nonrelativistic quark model. In pseudovector coupling also the numerical results for realistic-model parameters are close to those values. (orig.)

  9. Modeling DPOAE input/output function compression: comparisons with hearing thresholds.

    Science.gov (United States)

    Bhagat, Shaum P

    2014-09-01

    Basilar membrane input/output (I/O) functions in mammalian animal models are characterized by linear and compressed segments when measured near the location corresponding to the characteristic frequency. A method of studying basilar membrane compression indirectly in humans involves measuring distortion-product otoacoustic emission (DPOAE) I/O functions. Previous research has linked compression estimates from behavioral growth-of-masking functions to hearing thresholds. The aim of this study was to compare compression estimates from DPOAE I/O functions and hearing thresholds at 1 and 2 kHz. A prospective correlational research design was performed. The relationship between DPOAE I/O function compression estimates and hearing thresholds was evaluated with Pearson product-moment correlations. Normal-hearing adults (n = 16) aged 22-42 yr were recruited. DPOAE I/O functions (L₂ = 45-70 dB SPL) and two-interval forced-choice hearing thresholds were measured in normal-hearing adults. A three-segment linear regression model applied to DPOAE I/O functions supplied estimates of compression thresholds, defined as breakpoints between linear and compressed segments and the slopes of the compressed segments. Pearson product-moment correlations between DPOAE compression estimates and hearing thresholds were evaluated. A high correlation between DPOAE compression thresholds and hearing thresholds was observed at 2 kHz, but not at 1 kHz. Compression slopes also correlated highly with hearing thresholds only at 2 kHz. The derivation of cochlear compression estimates from DPOAE I/O functions provides a means to characterize basilar membrane mechanics in humans and elucidates the role of compression in tone detection in the 1-2 kHz frequency range. American Academy of Audiology.

  10. Multivariate Self-Exciting Threshold Autoregressive Models with eXogenous Input

    OpenAIRE

    Addo, Peter Martey

    2014-01-01

    This study defines a multivariate Self--Exciting Threshold Autoregressive with eXogenous input (MSETARX) models and present an estimation procedure for the parameters. The conditions for stationarity of the nonlinear MSETARX models is provided. In particular, the efficiency of an adaptive parameter estimation algorithm and LSE (least squares estimate) algorithm for this class of models is then provided via simulations.

  11. Framework for determining airport daily departure and arrival delay thresholds: statistical modelling approach.

    Science.gov (United States)

    Wesonga, Ronald; Nabugoomu, Fabian

    2016-01-01

    The study derives a framework for assessing airport efficiency through evaluating optimal arrival and departure delay thresholds. Assumptions of airport efficiency measurements, though based upon minimum numeric values such as 15 min of turnaround time, cannot be extrapolated to determine proportions of delay-days of an airport. This study explored the concept of delay threshold to determine the proportion of delay-days as an expansion of the theory of delay and our previous work. Data-driven approach using statistical modelling was employed to a limited set of determinants of daily delay at an airport. For the purpose of testing the efficacy of the threshold levels, operational data for Entebbe International Airport were used as a case study. Findings show differences in the proportions of delay at departure (μ = 0.499; 95 % CI = 0.023) and arrival (μ = 0.363; 95 % CI = 0.022). Multivariate logistic model confirmed an optimal daily departure and arrival delay threshold of 60 % for the airport given the four probable thresholds {50, 60, 70, 80}. The decision for the threshold value was based on the number of significant determinants, the goodness of fit statistics based on the Wald test and the area under the receiver operating curves. These findings propose a modelling framework to generate relevant information for the Air Traffic Management relevant in planning and measurement of airport operational efficiency.

  12. Examination of a multi-factorial model of body-related experiences during pregnancy: the relationships among physical symptoms, sleep quality, depression, self-esteem, and negative body attitudes.

    Science.gov (United States)

    Kamysheva, Ekaterina; Skouteris, Helen; Wertheim, Eleanor H; Paxton, Susan J; Milgrom, Jeannette

    2008-06-01

    The aim of this cross-sectional study was to investigate relationships among women's body attitudes, physical symptoms, self-esteem, depression, and sleep quality during pregnancy. Pregnant women (N=215) at 15-25 weeks gestation completed a questionnaire including four body image subscales assessing self-reported feeling fat, attractiveness, strength/fitness, and salience of weight and shape. Women reported on 29 pregnancy-related physical complaints, and completed the Beck Depression Inventory, Rosenberg Self-esteem Scale, and Pittsburgh Sleep Quality Index. In regressions, controlling for retrospective reports of body image, more frequent and intense physical symptoms were related to viewing the self as less strong/fit, and to poorer sleep quality and more depressive symptoms. In a multi-factorial model extending previous research, paths were found from sleep quality to depressive symptoms to self-esteem; self-esteem was found to be a mediator associated with lower scores on feeling fat and salience of weight and shape, and on higher perceived attractiveness.

  13. The R Package threg to Implement Threshold Regression Models

    Directory of Open Access Journals (Sweden)

    Tao Xiao

    2015-08-01

    This new package includes four functions: threg, and the methods hr, predict and plot for threg objects returned by threg. The threg function is the model-fitting function which is used to calculate regression coefficient estimates, asymptotic standard errors and p values. The hr method for threg objects is the hazard-ratio calculation function which provides the estimates of hazard ratios at selected time points for specified scenarios (based on given categories or value settings of covariates. The predict method for threg objects is used for prediction. And the plot method for threg objects provides plots for curves of estimated hazard functions, survival functions and probability density functions of the first-hitting-time; function curves corresponding to different scenarios can be overlaid in the same plot for comparison to give additional research insights.

  14. Multifactorial QT Interval Prolongation and Takotsubo Cardiomyopathy

    Directory of Open Access Journals (Sweden)

    Michael Gysel

    2014-01-01

    Full Text Available A 71-year-old woman collapsed while working as a grocery store cashier. CPR was performed and an AED revealed torsades de pointes (TdP. She was subsequently defibrillated resulting in restoration of sinus rhythm with a QTc interval of 544 msec. Further evaluation revealed a diagnosis of Takotsubo Cardiomyopathy (TCM contributing to the development of a multifactorial acquired long QT syndrome (LQTS. The case highlights the role of TCM as a cause of LQTS in the setting of multiple risk factors including old age, female gender, hypokalemia, and treatment with QT prolonging medications. It also highlights the multifactorial nature of acquired LQTS and lends support to growing evidence of an association with TCM.

  15. Poisson versus threshold models for genetic analysis of clinical mastitis in US Holsteins.

    Science.gov (United States)

    Vazquez, A I; Weigel, K A; Gianola, D; Bates, D M; Perez-Cabal, M A; Rosa, G J M; Chang, Y M

    2009-10-01

    Typically, clinical mastitis is coded as the presence or absence of disease in a given lactation, and records are analyzed with either linear models or binary threshold models. Because the presence of mastitis may include cows with multiple episodes, there is a loss of information when counts are treated as binary responses. Poisson models are appropriated for random variables measured as the number of events, and although these models are used extensively in studying the epidemiology of mastitis, they have rarely been used for studying the genetic aspects of mastitis. Ordinal threshold models are pertinent for ordered categorical responses; although one can hypothesize that the number of clinical mastitis episodes per animal reflects a continuous underlying increase in mastitis susceptibility, these models have rarely been used in genetic analysis of mastitis. The objective of this study was to compare probit, Poisson, and ordinal threshold models for the genetic evaluation of US Holstein sires for clinical mastitis. Mastitis was measured as a binary trait or as the number of mastitis cases. Data from 44,908 first-parity cows recorded in on-farm herd management software were gathered, edited, and processed for the present study. The cows were daughters of 1,861 sires, distributed over 94 herds. Predictive ability was assessed via a 5-fold cross-validation using 2 loss functions: mean squared error of prediction (MSEP) as the end point and a cost difference function. The heritability estimates were 0.061 for mastitis measured as a binary trait in the probit model and 0.085 and 0.132 for the number of mastitis cases in the ordinal threshold and Poisson models, respectively; because of scale differences, only the probit and ordinal threshold models are directly comparable. Among healthy animals, MSEP was smallest for the probit model, and the cost function was smallest for the ordinal threshold model. Among diseased animals, MSEP and the cost function were smallest

  16. Methods for Assessing Item, Step, and Threshold Invariance in Polytomous Items Following the Partial Credit Model

    Science.gov (United States)

    Penfield, Randall D.; Myers, Nicholas D.; Wolfe, Edward W.

    2008-01-01

    Measurement invariance in the partial credit model (PCM) can be conceptualized in several different but compatible ways. In this article the authors distinguish between three forms of measurement invariance in the PCM: step invariance, item invariance, and threshold invariance. Approaches for modeling these three forms of invariance are proposed,…

  17. Modeling, Simulation, and Analysis of Novel Threshold Voltage Definition for Nano-MOSFET

    Directory of Open Access Journals (Sweden)

    Yashu Swami

    2017-01-01

    Full Text Available Threshold voltage (VTH is the indispensable vital parameter in MOSFET designing, modeling, and operation. Diverse expounds and extraction methods exist to model the on-off transition characteristics of the device. The governing gauge for efficient threshold voltage definition and extraction method can be itemized as clarity, simplicity, precision, and stability throughout the operating conditions and technology node. The outcomes of extraction methods diverge from the exact values due to various short-channel effects (SCEs and nonidealities present in the device. A new approach to define and extract the real value of VTH of MOSFET is proposed in the manuscript. The subsequent novel enhanced SCE-independent VTH extraction method named “hybrid extrapolation VTH extraction method” (HEEM is elaborated, modeled, and compared with few prevalent MOSFET threshold voltage extraction methods for validation of the results. All the results are verified by extensive 2D TCAD simulation and confirmed analytically at various technology nodes.

  18. Effects of pump recycling technique on stimulated Brillouin scattering threshold: a theoretical model.

    Science.gov (United States)

    Al-Asadi, H A; Al-Mansoori, M H; Ajiya, M; Hitam, S; Saripan, M I; Mahdi, M A

    2010-10-11

    We develop a theoretical model that can be used to predict stimulated Brillouin scattering (SBS) threshold in optical fibers that arises through the effect of Brillouin pump recycling technique. Obtained simulation results from our model are in close agreement with our experimental results. The developed model utilizes single mode optical fiber of different lengths as the Brillouin gain media. For 5-km long single mode fiber, the calculated threshold power for SBS is about 16 mW for conventional technique. This value is reduced to about 8 mW when the residual Brillouin pump is recycled at the end of the fiber. The decrement of SBS threshold is due to longer interaction lengths between Brillouin pump and Stokes wave.

  19. Analytical modeling of threshold voltage for Cylindrical Gate All Around (CGAA MOSFET using center potential

    Directory of Open Access Journals (Sweden)

    K.P. Pradhan

    2015-12-01

    Full Text Available In this paper, an analytical threshold voltage model is proposed for a cylindrical gate-all-around (CGAA MOSFET by solving the 2-D Poisson’s equation in the cylindrical coordinate system. A comparison is made for both the center and the surface potential model of CGAA MOSFET. This paper claims that the calculation of threshold voltage using center potential is more accurate rather than the calculation from surface potential. The effects of the device parameters like the drain bias (VDS, oxide thickness (tox, channel thickness (r, etc., on the threshold voltage are also studied in this paper. The model is verified with 3D numerical device simulator Sentaurus from Synopsys Inc.

  20. Modeling Soil Quality Thresholds to Ecosystem Recovery at Fort Benning, Georgia, USA

    Energy Technology Data Exchange (ETDEWEB)

    Garten Jr., C.T.

    2004-03-08

    The objective of this research was to use a simple model of soil C and N dynamics to predict nutrient thresholds to ecosystem recovery on degraded soils at Fort Benning, Georgia, in the southeastern USA. The model calculates aboveground and belowground biomass, soil C inputs and dynamics, soil N stocks and availability, and plant N requirements. A threshold is crossed when predicted soil N supplies fall short of predicted N required to sustain biomass accrual at a specified recovery rate. Four factors were important to development of thresholds to recovery: (1) initial amounts of aboveground biomass, (2) initial soil C stocks (i.e., soil quality), (3) relative recovery rates of biomass, and (4) soil sand content. Thresholds to ecosystem recovery predicted by the model should not be interpreted independent of a specified recovery rate. Initial soil C stocks influenced the predicted patterns of recovery by both old field and forest ecosystems. Forests and old fields on soils with varying sand content had different predicted thresholds to recovery. Soil C stocks at barren sites on Fort Benning generally lie below predicted thresholds to 100% recovery of desired future ecosystem conditions defined on the basis of aboveground biomass (18000 versus 360 g m{sup -2} for forests and old fields, respectively). Calculations with the model indicated that reestablishment of vegetation on barren sites to a level below the desired future condition is possible at recovery rates used in the model, but the time to 100% recovery of desired future conditions, without crossing a nutrient threshold, is prolonged by a reduced rate of forest growth. Predicted thresholds to ecosystem recovery were less on soils with more than 70% sand content. The lower thresholds for old field and forest recovery on more sandy soils are apparently due to higher relative rates of net soil N mineralization in more sandy soils. Calculations with the model indicate that a combination of desired future

  1. Phase-change memory: A continuous multilevel compact model of subthreshold conduction and threshold switching

    Science.gov (United States)

    Pigot, Corentin; Gilibert, Fabien; Reyboz, Marina; Bocquet, Marc; Zuliani, Paola; Portal, Jean-Michel

    2018-04-01

    Phase-change memory (PCM) compact modeling of the threshold switching based on a thermal runaway in Poole–Frenkel conduction is proposed. Although this approach is often used in physical models, this is the first time it is implemented in a compact model. The model accuracy is validated by a good correlation between simulations and experimental data collected on a PCM cell embedded in a 90 nm technology. A wide range of intermediate states is measured and accurately modeled with a single set of parameters, allowing multilevel programing. A good convergence is exhibited even in snapback simulation owing to this fully continuous approach. Moreover, threshold properties extraction indicates a thermally enhanced switching, which validates the basic hypothesis of the model. Finally, it is shown that this model is compliant with a new drift-resilient cell-state metric. Once enriched with a phase transition module, this compact model is ready to be implemented in circuit simulators.

  2. An Analytic Approach to Developing Transport Threshold Models of Neoclassical Tearing Modes in Tokamaks

    International Nuclear Information System (INIS)

    Mikhailovskii, A.B.; Shirokov, M.S.; Konovalov, S.V.; Tsypin, V.S.

    2005-01-01

    Transport threshold models of neoclassical tearing modes in tokamaks are investigated analytically. An analysis is made of the competition between strong transverse heat transport, on the one hand, and longitudinal heat transport, longitudinal heat convection, longitudinal inertial transport, and rotational transport, on the other hand, which leads to the establishment of the perturbed temperature profile in magnetic islands. It is shown that, in all these cases, the temperature profile can be found analytically by using rigorous solutions to the heat conduction equation in the near and far regions of a chain of magnetic islands and then by matching these solutions. Analytic expressions for the temperature profile are used to calculate the contribution of the bootstrap current to the generalized Rutherford equation for the island width evolution with the aim of constructing particular transport threshold models of neoclassical tearing modes. Four transport threshold models, differing in the underlying competing mechanisms, are analyzed: collisional, convective, inertial, and rotational models. The collisional model constructed analytically is shown to coincide exactly with that calculated numerically; the reason is that the analytical temperature profile turns out to be the same as the numerical profile. The results obtained can be useful in developing the next generation of general threshold models. The first steps toward such models have already been made

  3. Threshold law for electron impact ionization in the model of Temkin and Poet

    International Nuclear Information System (INIS)

    Macek, J.H.

    1996-01-01

    The angle-Sturmian theory is used to derive the threshold law for ionization of atomic hydrogen by electron impact in the model of Temkin and Poet. In this model, the exact electron-electron interaction is replaced by its monopole term. As for Wannier's theory with the real interaction, ionization occurs only for electrons that start out nearly equidistant from the proton. Because there is a high propensity for one electron to be captured into a bound state, ionization is strongly suppressed, giving rise to a threshold law of the form σ ∝ exp[-aE -1/6 + bE 1/6 ], where a and b are constants. The exponential law appears to be the quantal counterpart of the classical offset of the ionization threshold. Relative energy distribution are computed and found to favor configurations with unequal energy sharing

  4. Model-dependence of the CO2 threshold for melting the hard Snowball Earth

    Directory of Open Access Journals (Sweden)

    W. R. Peltier

    2011-01-01

    Full Text Available One of the critical issues of the Snowball Earth hypothesis is the CO2 threshold for triggering the deglaciation. Using Community Atmospheric Model version 3.0 (CAM3, we study the problem for the CO2 threshold. Our simulations show large differences from previous results (e.g. Pierrehumbert, 2004, 2005; Le Hir et al., 2007. At 0.2 bars of CO2, the January maximum near-surface temperature is about 268 K, about 13 K higher than that in Pierrehumbert (2004, 2005, but lower than the value of 270 K for 0.1 bar of CO2 in Le Hir et al. (2007. It is found that the difference of simulation results is mainly due to model sensitivity of greenhouse effect and longwave cloud forcing to increasing CO2. At 0.2 bars of CO2, CAM3 yields 117 Wm−2 of clear-sky greenhouse effect and 32 Wm−2 of longwave cloud forcing, versus only about 77 Wm−2 and 10.5 Wm−2 in Pierrehumbert (2004, 2005, respectively. CAM3 has comparable clear-sky greenhouse effect to that in Le Hir et al. (2007, but lower longwave cloud forcing. CAM3 also produces much stronger Hadley cells than that in Pierrehumbert (2005. Effects of pressure broadening and collision-induced absorption are also studied using a radiative-convective model and CAM3. Both effects substantially increase surface temperature and thus lower the CO2 threshold. The radiative-convective model yields a CO2 threshold of about 0.21 bars with surface albedo of 0.663. Without considering the effects of pressure broadening and collision-induced absorption, CAM3 yields an approximate CO2 threshold of about 1.0 bar for surface albedo of about 0.6. However, the threshold is lowered to 0.38 bars as both effects are considered.

  5. Threshold Dynamics of a Stochastic SIR Model with Vertical Transmission and Vaccination

    OpenAIRE

    Miao, Anqi; Zhang, Jian; Zhang, Tongqian; Pradeep, B. G. Sampath Aruna

    2017-01-01

    A stochastic SIR model with vertical transmission and vaccination is proposed and investigated in this paper. The threshold dynamics are explored when the noise is small. The conditions for the extinction or persistence of infectious diseases are deduced. Our results show that large noise can lead to the extinction of infectious diseases which is conducive to epidemic diseases control.

  6. Threshold Dynamics of a Stochastic SIR Model with Vertical Transmission and Vaccination

    Directory of Open Access Journals (Sweden)

    Anqi Miao

    2017-01-01

    Full Text Available A stochastic SIR model with vertical transmission and vaccination is proposed and investigated in this paper. The threshold dynamics are explored when the noise is small. The conditions for the extinction or persistence of infectious diseases are deduced. Our results show that large noise can lead to the extinction of infectious diseases which is conducive to epidemic diseases control.

  7. Low level radiation: how does the linear without threshold model provide the safety of Canadian

    International Nuclear Information System (INIS)

    Anon.

    2010-01-01

    The linear without threshold model is a model of risk used worldwide by the most of health organisms of nuclear regulation in order to establish dose limits for workers and public. It is in the heart of the approach adopted by the Canadian commission of nuclear safety (C.C.S.N.) in matter of radiation protection. The linear without threshold model presumes reasonably it exists a direct link between radiation exposure and cancer rate. It does not exist scientific evidence that chronicle exposure to radiation doses under 100 milli sievert (mSv) leads harmful effects on health. Several scientific reports highlighted scientific evidences that seem indicate a low level of radiation is less harmful than the linear without threshold predicts. As the linear without threshold model presumes that any radiation exposure brings risks, the ALARA principle obliges the licensees to get the radiation exposure at the lowest reasonably achievable level, social and economical factors taken into account. ALARA principle constitutes a basic principle in the C.C.S.N. approach in matter of radiation protection; On the radiation protection plan, C.C.S.N. gets a careful approach that allows to provide health and safety of Canadian people and the protection of their environment. (N.C.)

  8. Threshold effects on renormalization group running of neutrino parameters in the low-scale seesaw model

    International Nuclear Information System (INIS)

    Bergstroem, Johannes; Ohlsson, Tommy; Zhang He

    2011-01-01

    We show that, in the low-scale type-I seesaw model, renormalization group running of neutrino parameters may lead to significant modifications of the leptonic mixing angles in view of so-called seesaw threshold effects. Especially, we derive analytical formulas for radiative corrections to neutrino parameters in crossing the different seesaw thresholds, and show that there may exist enhancement factors efficiently boosting the renormalization group running of the leptonic mixing angles. We find that, as a result of the seesaw threshold corrections to the leptonic mixing angles, various flavor symmetric mixing patterns (e.g., bi-maximal and tri-bimaximal mixing patterns) can be easily accommodated at relatively low energy scales, which is well within the reach of running and forthcoming experiments (e.g., the LHC).

  9. Modeling jointly low, moderate, and heavy rainfall intensities without a threshold selection

    KAUST Repository

    Naveau, Philippe

    2016-04-09

    In statistics, extreme events are often defined as excesses above a given large threshold. This definition allows hydrologists and flood planners to apply Extreme-Value Theory (EVT) to their time series of interest. Even in the stationary univariate context, this approach has at least two main drawbacks. First, working with excesses implies that a lot of observations (those below the chosen threshold) are completely disregarded. The range of precipitation is artificially shopped down into two pieces, namely large intensities and the rest, which necessarily imposes different statistical models for each piece. Second, this strategy raises a nontrivial and very practical difficultly: how to choose the optimal threshold which correctly discriminates between low and heavy rainfall intensities. To address these issues, we propose a statistical model in which EVT results apply not only to heavy, but also to low precipitation amounts (zeros excluded). Our model is in compliance with EVT on both ends of the spectrum and allows a smooth transition between the two tails, while keeping a low number of parameters. In terms of inference, we have implemented and tested two classical methods of estimation: likelihood maximization and probability weighed moments. Last but not least, there is no need to choose a threshold to define low and high excesses. The performance and flexibility of this approach are illustrated on simulated and hourly precipitation recorded in Lyon, France.

  10. A flexible cure rate model with dependent censoring and a known cure threshold.

    Science.gov (United States)

    Bernhardt, Paul W

    2016-11-10

    We propose a flexible cure rate model that accommodates different censoring distributions for the cured and uncured groups and also allows for some individuals to be observed as cured when their survival time exceeds a known threshold. We model the survival times for the uncured group using an accelerated failure time model with errors distributed according to the seminonparametric distribution, potentially truncated at a known threshold. We suggest a straightforward extension of the usual expectation-maximization algorithm approach for obtaining estimates in cure rate models to accommodate the cure threshold and dependent censoring. We additionally suggest a likelihood ratio test for testing for the presence of dependent censoring in the proposed cure rate model. We show through numerical studies that our model has desirable properties and leads to approximately unbiased parameter estimates in a variety of scenarios. To demonstrate how our method performs in practice, we analyze data from a bone marrow transplantation study and a liver transplant study. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  11. A probabilistic Poisson-based model accounts for an extensive set of absolute auditory threshold measurements.

    Science.gov (United States)

    Heil, Peter; Matysiak, Artur; Neubauer, Heinrich

    2017-09-01

    Thresholds for detecting sounds in quiet decrease with increasing sound duration in every species studied. The neural mechanisms underlying this trade-off, often referred to as temporal integration, are not fully understood. Here, we probe the human auditory system with a large set of tone stimuli differing in duration, shape of the temporal amplitude envelope, duration of silent gaps between bursts, and frequency. Duration was varied by varying the plateau duration of plateau-burst (PB) stimuli, the duration of the onsets and offsets of onset-offset (OO) stimuli, and the number of identical bursts of multiple-burst (MB) stimuli. Absolute thresholds for a large number of ears (>230) were measured using a 3-interval-3-alternative forced choice (3I-3AFC) procedure. Thresholds decreased with increasing sound duration in a manner that depended on the temporal envelope. Most commonly, thresholds for MB stimuli were highest followed by thresholds for OO and PB stimuli of corresponding durations. Differences in the thresholds for MB and OO stimuli and in the thresholds for MB and PB stimuli, however, varied widely across ears, were negative in some ears, and were tightly correlated. We show that the variation and correlation of MB-OO and MB-PB threshold differences are linked to threshold microstructure, which affects the relative detectability of the sidebands of the MB stimuli and affects estimates of the bandwidth of auditory filters. We also found that thresholds for MB stimuli increased with increasing duration of the silent gaps between bursts. We propose a new model and show that it accurately accounts for our results and does so considerably better than a leaky-integrator-of-intensity model and a probabilistic model proposed by others. Our model is based on the assumption that sensory events are generated by a Poisson point process with a low rate in the absence of stimulation and higher, time-varying rates in the presence of stimulation. A subject in a 3I-3AFC

  12. Modeling the residual effects and threshold saturation of training: a case study of Olympic swimmers.

    Science.gov (United States)

    Hellard, Philippe; Avalos, Marta; Millet, Gregoire; Lacoste, Lucien; Barale, Frederic; Chatard, Jean-Claude

    2005-02-01

    The aim of this study was to model the residual effects of training on the swimming performance and to compare a model that includes threshold saturation (MM) with the Banister model (BM). Seven Olympic swimmers were studied over a period of 4 +/- 2 years. For 3 training loads (low-intensity w(LIT), high-intensity w(HIT), and strength training w(ST)), 3 residual training effects were determined: short-term (STE) during the taper phase (i.e., 3 weeks before the performance [weeks 0, 1, and 2]), intermediate-term (ITE) during the intensity phase (weeks 3, 4, and 5), and long-term (LTE) during the volume phase (weeks 6, 7, and 8). ITE and LTE were positive for w(HIT) and w(LIT), respectively (p measures indicated that MM compares favorably with BM. Identifying individual training thresholds may help individualize the distribution of training loads.

  13. Ionizing radiation and genetic risks. Part VIII. The concept of mutation component and its use in risk estimation for multifactorial diseases

    Energy Technology Data Exchange (ETDEWEB)

    Denniston, C. [Laboratory of Genetics, University of Wisconsin-Madison, Madison (United States); Chakraborty, R. [Human Genetics Center, University of Texas School of Public Health, P.O. Box 20334, Houston, TX (United States); Sankaranarayanan, K. [Department of Radiation Genetics and Chemical Mutagenesis, Sylvius Laboratories, Leiden University Medical Centre, Wassenaarseweg 72, 2333 AL Leiden (Netherlands)

    1998-08-31

    Multifactorial diseases, which include the common congenital abnormalities (incidence: 6%) and chronic diseases with onset predominantly in adults (population prevalence: 65%), contribute substantially to human morbidity and mortality. Their transmission patterns do not conform to Mendelian expectations. The model most frequently used to explain their inheritance and to estimate risks to relatives is a Multifactorial Threshold Model (MTM) of disease liability. The MTM assumes that: (1) the disease is due to the joint action of a large number of genetic and environmental factors, each of which contributing a small amount of liability, (2) the distribution of liability in the population is Gaussian and (3) individuals whose liability exceeds a certain threshold value are affected by the disease. For most of these diseases, the number of genes involved or the environmental factors are not fully known. In the context of radiation exposures of the population, the question of the extent to which induced mutations will cause an increase in the frequencies of these diseases has remained unanswered. In this paper, we address this problem by using a modified version of MTM which incorporates mutation and selection as two additional parameters. The model assumes a finite number of gene loci and threshold of liability (hence, the designation, Finite-Locus Threshold Model or FLTM). The FLTM permits one to examine the relationship between broad-sense heritability of disease liability and mutation component (MC), the responsiveness of the disease to a change in mutation rate. Through the use of a computer program (in which mutation rate, selection, threshold, recombination rate and environmental variance are input parameters and MC and heritability of liability are output estimates), we studied the MC-heritability relationship for (1) a permanent increase in mutation rate (e.g., when the population sustains radiation exposure in every generation) and (2) a one-time increase in

  14. Prediction Model and Principle of End-of-Life Threshold for Lithium Ion Batteries Based on Open Circuit Voltage Drifts

    International Nuclear Information System (INIS)

    Cui, Yingzhi; Yang, Jie; Du, Chunyu; Zuo, Pengjian; Gao, Yunzhi; Cheng, Xinqun; Ma, Yulin; Yin, Geping

    2017-01-01

    Highlights: •Open circuit voltage evolution over ageing of lithium ion batteries is deciphered. •The mechanism responsible for the end-of-life (EOL) threshold is elaborated. •A new prediction model of EOL threshold with improved accuracy is developed. •This EOL prediction model is promising for the applications in electric vehicles. -- Abstract: The end-of-life (EOL) of a lithium ion battery (LIB) is defined as the time point when the LIB can no longer provide sufficient power or energy to accomplish its intended function. Generally, the EOL occurs abruptly when the degradation of a LIB reaches the threshold. Therefore, current prediction methods of EOL by extrapolating the early degradation behavior often result in significant errors. To address this problem, this paper analyzes the reason for the EOL threshold of a LIB with shallow depth of discharge. It is found that the sudden appearance of EOL threshold results from the drift of open circuit voltage (OCV) at the end of both shallow depth and full discharges. Further, a new EOL threshold prediction model with highly improved accuracy is developed based on the OCV drifts and their evolution mechanism, which can effectively avoid the misjudgment of EOL threshold. The accuracy of this EOL threshold prediction model is verified by comparing with experimental results. The EOL threshold prediction model can be applied to other battery chemistry systems and its possible application in electric vehicles is finally discussed.

  15. Model for fitting longitudinal traits subject to threshold response applied to genetic evaluation for heat tolerance

    Directory of Open Access Journals (Sweden)

    Misztal Ignacy

    2009-01-01

    Full Text Available Abstract A semi-parametric non-linear longitudinal hierarchical model is presented. The model assumes that individual variation exists both in the degree of the linear change of performance (slope beyond a particular threshold of the independent variable scale and in the magnitude of the threshold itself; these individual variations are attributed to genetic and environmental components. During implementation via a Bayesian MCMC approach, threshold levels were sampled using a Metropolis step because their fully conditional posterior distributions do not have a closed form. The model was tested by simulation following designs similar to previous studies on genetics of heat stress. Posterior means of parameters of interest, under all simulation scenarios, were close to their true values with the latter always being included in the uncertain regions, indicating an absence of bias. The proposed models provide flexible tools for studying genotype by environmental interaction as well as for fitting other longitudinal traits subject to abrupt changes in the performance at particular points on the independent variable scale.

  16. ATHEROSCLEROSIS DISEASE: A MULTI-FACTORIAL PATHOLOGY

    Directory of Open Access Journals (Sweden)

    Marcieli da Luz Giroldo1; Arienne Serrano Alves1; Francielle Baptista1

    2007-06-01

    Full Text Available Atherosclerosis or arterial stiffening is a gradual disease that restricts the normal blood flow in different areas of body and maylead to secondary illnesses as myocardial infarction and cerebral stroke. Innumerable factors are related to the development ofatherosclerosis, among them are the dyslipidemia; genetic factors; arterial hypertension; diabetes mellitus; obesity; smoking;lack of exercise; pulmonary infection by Chlamydia and stress. Due to multi-factorial atherosclerosis characteristics,innumerable drugs, with differentiated mechanisms of action, are being elaborated to be used in prevention and control of thisdisease. However, beyond the pharmacological therapy, a balanced diet, physical activity and elimination of risk habits, assmoking, also are need for controlling atherosclerosis progression, as well as for the increase of expectative and quality of life

  17. Some Observations about the Nearest-Neighbor Model of the Error Threshold

    International Nuclear Information System (INIS)

    Gerrish, Philip J.

    2009-01-01

    I explore some aspects of the 'error threshold' - a critical mutation rate above which a population is nonviable. The phase transition that occurs as mutation rate crosses this threshold has been shown to be mathematically equivalent to the loss of ferromagnetism that occurs as temperature exceeds the Curie point. I will describe some refinements and new results based on the simplest of these mutation models, will discuss the commonly unperceived robustness of this simple model, and I will show some preliminary results comparing qualitative predictions with simulations of finite populations adapting at high mutation rates. I will talk about how these qualitative predictions are relevant to biomedical science and will discuss how my colleagues and I are looking for phase-transition signatures in real populations of Escherichia coli that go extinct as a result of excessive mutation.

  18. A Rational Threshold Signature Model and Protocol Based on Different Permissions

    Directory of Open Access Journals (Sweden)

    Bojun Wang

    2014-01-01

    Full Text Available This paper develops a novel model and protocol used in some specific scenarios, in which the participants of multiple groups with different permissions can finish the signature together. We apply the secret sharing scheme based on difference equation to the private key distribution phase and secret reconstruction phrase of our threshold signature scheme. In addition, our scheme can achieve the signature success because of the punishment strategy of the repeated rational secret sharing. Besides, the bit commitment and verification method used to detect players’ cheating behavior acts as a contributing factor to prevent the internal fraud. Using bit commitments, verifiable parameters, and time sequences, this paper constructs a dynamic game model, which has the features of threshold signature management with different permissions, cheat proof, and forward security.

  19. Interaction of radon and smoking among Czech uranium miners using model of a threshold energy

    International Nuclear Information System (INIS)

    Boehm, R.; Holy, K.; Sedlak, A.

    2014-01-01

    Exposure to radon and smoking are among the most important factors influencing the risk of lung cancer. However, the joint effect of radon and smoking has not been sufficiently investigated so far. In this paper we will try to describe by means of a threshold energy model the mechanism of synergic effect of the aforementioned factors, and compare their influence on the risk of lung cancer. The model is based on the assumption that the inactivation of cells is caused by the excess of threshold specific energy z0 in the sensitive volume of the cell. Cigarette smoking causes, among others, an increase in the synthesis of the survivin protein that protects cells from apoptosis and thereby reduces their radiosensitivity. Survivin is therefore responsible for the increase of threshold energy z0, which in turn leads to the increase of lung cancer risk. A linear relationship between the threshold energy and the number of cigarettes smoked was assumed. The effect of smoking on radon exposure was evaluated for various groups of smokers that were defined by the degree of morphometric and geometric changes in the lungs induced by smoking and various degrees of chronic obstructive pulmonary disease. We simulate various scenarios of irradiation - short-term exposure, long-term exposure, as well as various smoking habits - smoker, ex-smoker. The calculated values can be, to an extent, compared to the epidemiological analysis geometric mixture models of Tomasek, who statistically evaluated epidemiological data about lung cancer occurrence among miners working in Jachymov and Pribram mines. From the results it follows that the correlation coefficient was particularly high. Although the approach outlined in this paper is only one of the many that strive to describe in detail the synergic effect of smoking and exposition, the used model can contribute to a more precise estimate of lung cancer risk in areas with various smoking habits. (authors)

  20. The threshold of a stochastic avian-human influenza epidemic model with psychological effect

    Science.gov (United States)

    Zhang, Fengrong; Zhang, Xinhong

    2018-02-01

    In this paper, a stochastic avian-human influenza epidemic model with psychological effect in human population and saturation effect within avian population is investigated. This model describes the transmission of avian influenza among avian population and human population in random environments. For stochastic avian-only system, persistence in the mean and extinction of the infected avian population are studied. For the avian-human influenza epidemic system, sufficient conditions for the existence of an ergodic stationary distribution are obtained. Furthermore, a threshold of this stochastic model which determines the outcome of the disease is obtained. Finally, numerical simulations are given to support the theoretical results.

  1. Threshold law for the triplet state for electron-impact ionization in the Temkin-Poet model

    International Nuclear Information System (INIS)

    Ihra, W.; Mota-Furtado, F.; OMahony, P.F.; Macek, J.H.

    1997-01-01

    We derive the analytical threshold behavior for the triplet cross section for electron-impact ionization in the Temkin-Poet model. The analytical results indicate that the most recent numerical calculations may fail to reproduce the correct threshold behavior in an energy regime below about E=0.1 a.u. We also present an analytical expression for the energy distribution of the two electrons near threshold. copyright 1997 The American Physical Society

  2. Linear non-threshold (LNT) radiation hazards model and its evaluation

    International Nuclear Information System (INIS)

    Min Rui

    2011-01-01

    In order to introduce linear non-threshold (LNT) model used in study on the dose effect of radiation hazards and to evaluate its application, the analysis of comprehensive literatures was made. The results show that LNT model is more suitable to describe the biological effects in accuracy for high dose than that for low dose. Repairable-conditionally repairable model of cell radiation effects can be well taken into account on cell survival curve in the all conditions of high, medium and low absorbed dose range. There are still many uncertainties in assessment model of effective dose of internal radiation based on the LNT assumptions and individual mean organ equivalent, and it is necessary to establish gender-specific voxel human model, taking gender differences into account. From above, the advantages and disadvantages of various models coexist. Before the setting of the new theory and new model, LNT model is still the most scientific attitude. (author)

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

    Directory of Open Access Journals (Sweden)

    R. Christopher Sheldrick

    2016-11-01

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

  4. Critical thresholds for eventual extinction in randomly disturbed population growth models.

    Science.gov (United States)

    Peckham, Scott D; Waymire, Edward C; De Leenheer, Patrick

    2018-02-16

    This paper considers several single species growth models featuring a carrying capacity, which are subject to random disturbances that lead to instantaneous population reduction at the disturbance times. This is motivated in part by growing concerns about the impacts of climate change. Our main goal is to understand whether or not the species can persist in the long run. We consider the discrete-time stochastic process obtained by sampling the system immediately after the disturbances, and find various thresholds for several modes of convergence of this discrete process, including thresholds for the absence or existence of a positively supported invariant distribution. These thresholds are given explicitly in terms of the intensity and frequency of the disturbances on the one hand, and the population's growth characteristics on the other. We also perform a similar threshold analysis for the original continuous-time stochastic process, and obtain a formula that allows us to express the invariant distribution for this continuous-time process in terms of the invariant distribution of the discrete-time process, and vice versa. Examples illustrate that these distributions can differ, and this sends a cautionary message to practitioners who wish to parameterize these and related models using field data. Our analysis relies heavily on a particular feature shared by all the deterministic growth models considered here, namely that their solutions exhibit an exponentially weighted averaging property between a function of the initial condition, and the same function applied to the carrying capacity. This property is due to the fact that these systems can be transformed into affine systems.

  5. Improved bounds on the epidemic threshold of exact SIS models on complex networks

    KAUST Repository

    Ruhi, Navid Azizan; Thrampoulidis, Christos; Hassibi, Babak

    2017-01-01

    The SIS (susceptible-infected-susceptible) epidemic model on an arbitrary network, without making approximations, is a 2n-state Markov chain with a unique absorbing state (the all-healthy state). This makes analysis of the SIS model and, in particular, determining the threshold of epidemic spread quite challenging. It has been shown that the exact marginal probabilities of infection can be upper bounded by an n-dimensional linear time-invariant system, a consequence of which is that the Markov chain is “fast-mixing” when the LTI system is stable, i.e. when equation (where β is the infection rate per link, δ is the recovery rate, and λmax(A) is the largest eigenvalue of the network's adjacency matrix). This well-known threshold has been recently shown not to be tight in several cases, such as in a star network. In this paper, we provide tighter upper bounds on the exact marginal probabilities of infection, by also taking pairwise infection probabilities into account. Based on this improved bound, we derive tighter eigenvalue conditions that guarantee fast mixing (i.e., logarithmic mixing time) of the chain. We demonstrate the improvement of the threshold condition by comparing the new bound with the known one on various networks with various epidemic parameters.

  6. Improved bounds on the epidemic threshold of exact SIS models on complex networks

    KAUST Repository

    Ruhi, Navid Azizan

    2017-01-05

    The SIS (susceptible-infected-susceptible) epidemic model on an arbitrary network, without making approximations, is a 2n-state Markov chain with a unique absorbing state (the all-healthy state). This makes analysis of the SIS model and, in particular, determining the threshold of epidemic spread quite challenging. It has been shown that the exact marginal probabilities of infection can be upper bounded by an n-dimensional linear time-invariant system, a consequence of which is that the Markov chain is “fast-mixing” when the LTI system is stable, i.e. when equation (where β is the infection rate per link, δ is the recovery rate, and λmax(A) is the largest eigenvalue of the network\\'s adjacency matrix). This well-known threshold has been recently shown not to be tight in several cases, such as in a star network. In this paper, we provide tighter upper bounds on the exact marginal probabilities of infection, by also taking pairwise infection probabilities into account. Based on this improved bound, we derive tighter eigenvalue conditions that guarantee fast mixing (i.e., logarithmic mixing time) of the chain. We demonstrate the improvement of the threshold condition by comparing the new bound with the known one on various networks with various epidemic parameters.

  7. Kuramoto model with uniformly spaced frequencies: Finite-N asymptotics of the locking threshold.

    Science.gov (United States)

    Ottino-Löffler, Bertrand; Strogatz, Steven H

    2016-06-01

    We study phase locking in the Kuramoto model of coupled oscillators in the special case where the number of oscillators, N, is large but finite, and the oscillators' natural frequencies are evenly spaced on a given interval. In this case, stable phase-locked solutions are known to exist if and only if the frequency interval is narrower than a certain critical width, called the locking threshold. For infinite N, the exact value of the locking threshold was calculated 30 years ago; however, the leading corrections to it for finite N have remained unsolved analytically. Here we derive an asymptotic formula for the locking threshold when N≫1. The leading correction to the infinite-N result scales like either N^{-3/2} or N^{-1}, depending on whether the frequencies are evenly spaced according to a midpoint rule or an end-point rule. These scaling laws agree with numerical results obtained by Pazó [D. Pazó, Phys. Rev. E 72, 046211 (2005)PLEEE81539-375510.1103/PhysRevE.72.046211]. Moreover, our analysis yields the exact prefactors in the scaling laws, which also match the numerics.

  8. Threshold Dynamics in Stochastic SIRS Epidemic Models with Nonlinear Incidence and Vaccination

    Directory of Open Access Journals (Sweden)

    Lei Wang

    2017-01-01

    Full Text Available In this paper, the dynamical behaviors for a stochastic SIRS epidemic model with nonlinear incidence and vaccination are investigated. In the models, the disease transmission coefficient and the removal rates are all affected by noise. Some new basic properties of the models are found. Applying these properties, we establish a series of new threshold conditions on the stochastically exponential extinction, stochastic persistence, and permanence in the mean of the disease with probability one for the models. Furthermore, we obtain a sufficient condition on the existence of unique stationary distribution for the model. Finally, a series of numerical examples are introduced to illustrate our main theoretical results and some conjectures are further proposed.

  9. Consequences of the genetic threshold model for observing partial migration under climate change scenarios.

    Science.gov (United States)

    Cobben, Marleen M P; van Noordwijk, Arie J

    2017-10-01

    Migration is a widespread phenomenon across the animal kingdom as a response to seasonality in environmental conditions. Partially migratory populations are populations that consist of both migratory and residential individuals. Such populations are very common, yet their stability has long been debated. The inheritance of migratory activity is currently best described by the threshold model of quantitative genetics. The inclusion of such a genetic threshold model for migratory behavior leads to a stable zone in time and space of partially migratory populations under a wide range of demographic parameter values, when assuming stable environmental conditions and unlimited genetic diversity. Migratory species are expected to be particularly sensitive to global warming, as arrival at the breeding grounds might be increasingly mistimed as a result of the uncoupling of long-used cues and actual environmental conditions, with decreasing reproduction as a consequence. Here, we investigate the consequences for migratory behavior and the stability of partially migratory populations under five climate change scenarios and the assumption of a genetic threshold value for migratory behavior in an individual-based model. The results show a spatially and temporally stable zone of partially migratory populations after different lengths of time in all scenarios. In the scenarios in which the species expands its range from a particular set of starting populations, the genetic diversity and location at initialization determine the species' colonization speed across the zone of partial migration and therefore across the entire landscape. Abruptly changing environmental conditions after model initialization never caused a qualitative change in phenotype distributions, or complete extinction. This suggests that climate change-induced shifts in species' ranges as well as changes in survival probabilities and reproductive success can be met with flexibility in migratory behavior at the

  10. Cumulative t-link threshold models for the genetic analysis of calving ease scores

    Directory of Open Access Journals (Sweden)

    Tempelman Robert J

    2003-09-01

    Full Text Available Abstract In this study, a hierarchical threshold mixed model based on a cumulative t-link specification for the analysis of ordinal data or more, specifically, calving ease scores, was developed. The validation of this model and the Markov chain Monte Carlo (MCMC algorithm was carried out on simulated data from normally and t4 (i.e. a t-distribution with four degrees of freedom distributed populations using the deviance information criterion (DIC and a pseudo Bayes factor (PBF measure to validate recently proposed model choice criteria. The simulation study indicated that although inference on the degrees of freedom parameter is possible, MCMC mixing was problematic. Nevertheless, the DIC and PBF were validated to be satisfactory measures of model fit to data. A sire and maternal grandsire cumulative t-link model was applied to a calving ease dataset from 8847 Italian Piemontese first parity dams. The cumulative t-link model was shown to lead to posterior means of direct and maternal heritabilities (0.40 ± 0.06, 0.11 ± 0.04 and a direct maternal genetic correlation (-0.58 ± 0.15 that were not different from the corresponding posterior means of the heritabilities (0.42 ± 0.07, 0.14 ± 0.04 and the genetic correlation (-0.55 ± 0.14 inferred under the conventional cumulative probit link threshold model. Furthermore, the correlation (> 0.99 between posterior means of sire progeny merit from the two models suggested no meaningful rerankings. Nevertheless, the cumulative t-link model was decisively chosen as the better fitting model for this calving ease data using DIC and PBF.

  11. Analytical details of the instability threshold of the laser-Lorenz model

    International Nuclear Information System (INIS)

    Bakasov, A.A.; Abraham, N.B.

    1992-11-01

    An exact analysis of the second threshold of a single-mode homogeneously broadened laser is given for the most general operating conditions. We provide a general analytical proof that increasing the detuning increases the second threshold is given. An analysis of the second threshold at a fixed detuning and of the ratio of the second threshold to the first threshold reveals that the smallest values occur when the population relaxation rate is minimized. (author). 13 refs, 4 figs, 2 tabs

  12. How Stuttering Develops: The Multifactorial Dynamic Pathways Theory

    Science.gov (United States)

    Smith, Anne; Weber, Christine

    2017-01-01

    Purpose: We advanced a multifactorial, dynamic account of the complex, nonlinear interactions of motor, linguistic, and emotional factors contributing to the development of stuttering. Our purpose here is to update our account as the multifactorial dynamic pathways theory. Method: We review evidence related to how stuttering develops, including…

  13. Stochastic Threshold Microdose Model for Cell Killing by Insoluble Metallic Nanomaterial Particles

    Science.gov (United States)

    Scott, Bobby R.

    2010-01-01

    This paper introduces a novel microdosimetric model for metallic nanomaterial-particles (MENAP)-induced cytotoxicity. The focus is on the engineered insoluble MENAP which represent a significant breakthrough in the design and development of new products for consumers, industry, and medicine. Increased production is rapidly occurring and may cause currently unrecognized health effects (e.g., nervous system dysfunction, heart disease, cancer); thus, dose-response models for MENAP-induced biological effects are needed to facilitate health risk assessment. The stochastic threshold microdose (STM) model presented introduces novel stochastic microdose metrics for use in constructing dose-response relationships for the frequency of specific cellular (e.g., cell killing, mutations, neoplastic transformation) or subcellular (e.g., mitochondria dysfunction) effects. A key metric is the exposure-time-dependent, specific burden (MENAP count) for a given critical target (e.g., mitochondria, nucleus). Exceeding a stochastic threshold specific burden triggers cell death. For critical targets in the cytoplasm, the autophagic mode of death is triggered. For the nuclear target, the apoptotic mode of death is triggered. Overall cell survival is evaluated for the indicated competing modes of death when both apply. The STM model can be applied to cytotoxicity data using Bayesian methods implemented via Markov chain Monte Carlo. PMID:21191483

  14. Two-dimensional threshold voltage analytical model of DMG strained-silicon-on-insulator MOSFETs

    International Nuclear Information System (INIS)

    Li Jin; Liu Hongxia; Li Bin; Cao Lei; Yuan Bo

    2010-01-01

    For the first time, a simple and accurate two-dimensional analytical model for the surface potential variation along the channel in fully depleted dual-material gate strained-Si-on-insulator (DMG SSOI) MOSFETs is developed. We investigate the improved short channel effect (SCE), hot carrier effect (HCE), drain-induced barrier-lowering (DIBL) and carrier transport efficiency for the novel structure MOSFET. The analytical model takes into account the effects of different metal gate lengths, work functions, the drain bias and Ge mole fraction in the relaxed SiGe buffer. The surface potential in the channel region exhibits a step potential, which can suppress SCE, HCE and DIBL. Also, strained-Si and SOI structure can improve the carrier transport efficiency, with strained-Si being particularly effective. Further, the threshold voltage model correctly predicts a 'rollup' in threshold voltage with decreasing channel length ratios or Ge mole fraction in the relaxed SiGe buffer. The validity of the two-dimensional analytical model is verified using numerical simulations. (semiconductor devices)

  15. Semi-empirical model for the threshold voltage of a double implanted MOSFET and its temperature dependence

    Energy Technology Data Exchange (ETDEWEB)

    Arora, N D

    1987-05-01

    A simple and accurate semi-empirical model for the threshold voltage of a small geometry double implanted enhancement type MOSFET, especially useful in a circuit simulation program like SPICE, has been developed. The effect of short channel length and narrow width on the threshold voltage has been taken into account through a geometrical approximation, which involves parameters whose values can be determined from the curve fitting experimental data. A model for the temperature dependence of the threshold voltage for the implanted devices has also been presented. The temperature coefficient of the threshold voltage was found to change with decreasing channel length and width. Experimental results from various device sizes, both short and narrow, show very good agreement with the model. The model has been implemented in SPICE as part of the complete dc model.

  16. Corrections to scaling in random resistor networks and diluted continuous spin models near the percolation threshold.

    Science.gov (United States)

    Janssen, Hans-Karl; Stenull, Olaf

    2004-02-01

    We investigate corrections to scaling induced by irrelevant operators in randomly diluted systems near the percolation threshold. The specific systems that we consider are the random resistor network and a class of continuous spin systems, such as the x-y model. We focus on a family of least irrelevant operators and determine the corrections to scaling that originate from this family. Our field theoretic analysis carefully takes into account that irrelevant operators mix under renormalization. It turns out that long standing results on corrections to scaling are respectively incorrect (random resistor networks) or incomplete (continuous spin systems).

  17. Metro passengers’ route choice model and its application considering perceived transfer threshold

    Science.gov (United States)

    Jin, Fanglei; Zhang, Yongsheng; Liu, Shasha

    2017-01-01

    With the rapid development of the Metro network in China, the greatly increased route alternatives make passengers’ route choice behavior and passenger flow assignment more complicated, which presents challenges to the operation management. In this paper, a path sized logit model is adopted to analyze passengers’ route choice preferences considering such parameters as in-vehicle time, number of transfers, and transfer time. Moreover, the “perceived transfer threshold” is defined and included in the utility function to reflect the penalty difference caused by transfer time on passengers’ perceived utility under various numbers of transfers. Next, based on the revealed preference data collected in the Guangzhou Metro, the proposed model is calibrated. The appropriate perceived transfer threshold value and the route choice preferences are analyzed. Finally, the model is applied to a personalized route planning case to demonstrate the engineering practicability of route choice behavior analysis. The results show that the introduction of the perceived transfer threshold is helpful to improve the model’s explanatory abilities. In addition, personalized route planning based on route choice preferences can meet passengers’ diversified travel demands. PMID:28957376

  18. Modeling the residual effects and threshold saturation of training: a case study of Olympic swimmers

    Science.gov (United States)

    Hellard, Philippe; Avalos, Marta; Millet, Grégoire; Lacoste, Lucien; Barale, Frédéric; Chatard, Jean-Claude

    2005-01-01

    The aim of this study was to model the residual effects of training on the swimming performance and to compare a model including threshold saturation (MM) to the Banister model (BM). Seven Olympic swimmers were studied over a period of 4 ± 2 years. For three training loads (low-intensity wLIT, high-intensity wHIT and strength training wST), three residual training effects were determined: short-term (STE) during the taper phase, i.e. three weeks before the performance (weeks 0, −1, −2), intermediate-term (ITE) during the intensity phase (weeks −3, −4 and −5) and long-term (LTE) during the volume phase (weeks −6, −7, −8). ITE and LTE were positive for wHIT and wLIT, respectively (P < 0.05). wLIT during taper was related to performances by a parabolic relationship (P < 0.05). Different quality measures indicated that MM compares favorably with BM. Identifying individual training thresholds may help individualizing the distribution of training loads. PMID:15705048

  19. Stochastic Threshold Exponential (TE) Model for Hematopoietic Tissue Reconstitution Deficit after Radiation Damage.

    Science.gov (United States)

    Scott, B R; Potter, C A

    2014-07-01

    Whole-body exposure to large radiation doses can cause severe loss of hematopoietic tissue cells and threaten life if the lost cells are not replaced in a timely manner through natural repopulation (a homeostatic mechanism). Repopulation to the baseline level N 0 is called reconstitution and a reconstitution deficit (repopulation shortfall) can occur in a dose-related and organ-specific manner. Scott et al. (2013) previously introduced a deterministic version of a threshold exponential (TE) model of tissue-reconstitution deficit at a given follow-up time that was applied to bone marrow and spleen cellularity (number of constituent cells) data obtained 6 weeks after whole-body gamma-ray exposure of female C.B-17 mice. In this paper a more realistic, stochastic version of the TE model is provided that allows radiation response to vary between different individuals. The Stochastic TE model is applied to post gamma-ray-exposure cellularity data previously reported and also to more limited X-ray cellularity data for whole-body irradiated female C.B-17 mice. Results indicate that the population average threshold for a tissue reconstitution deficit appears to be similar for bone marrow and spleen and for 320-kV-spectrum X-rays and Cs-137 gamma rays. This means that 320-kV spectrum X-rays could successfully be used in conducting such studies.

  20. Genetic evaluation of calf and heifer survival in Iranian Holstein cattle using linear and threshold models.

    Science.gov (United States)

    Forutan, M; Ansari Mahyari, S; Sargolzaei, M

    2015-02-01

    Calf and heifer survival are important traits in dairy cattle affecting profitability. This study was carried out to estimate genetic parameters of survival traits in female calves at different age periods, until nearly the first calving. Records of 49,583 female calves born during 1998 and 2009 were considered in five age periods as days 1-30, 31-180, 181-365, 366-760 and full period (day 1-760). Genetic components were estimated based on linear and threshold sire models and linear animal models. The models included both fixed effects (month of birth, dam's parity number, calving ease and twin/single) and random effects (herd-year, genetic effect of sire or animal and residual). Rates of death were 2.21, 3.37, 1.97, 4.14 and 12.4% for the above periods, respectively. Heritability estimates were very low ranging from 0.48 to 3.04, 0.62 to 3.51 and 0.50 to 4.24% for linear sire model, animal model and threshold sire model, respectively. Rank correlations between random effects of sires obtained with linear and threshold sire models and with linear animal and sire models were 0.82-0.95 and 0.61-0.83, respectively. The estimated genetic correlations between the five different periods were moderate and only significant for 31-180 and 181-365 (r(g) = 0.59), 31-180 and 366-760 (r(g) = 0.52), and 181-365 and 366-760 (r(g) = 0.42). The low genetic correlations in current study would suggest that survival at different periods may be affected by the same genes with different expression or by different genes. Even though the additive genetic variations of survival traits were small, it might be possible to improve these traits by traditional or genomic selection. © 2014 Blackwell Verlag GmbH.

  1. A Nonlinear Transmission Line Model of the Cochlea With Temporal Integration Accounts for Duration Effects in Threshold Fine Structure

    DEFF Research Database (Denmark)

    Verhey, Jesko L.; Mauermann, Manfred; Epp, Bastian

    2017-01-01

    For normal-hearing listeners, auditory pure-tone thresholds in quiet often show quasi periodic fluctuations when measured with a high frequency resolution, referred to as threshold fine structure. Threshold fine structure is dependent on the stimulus duration, with smaller fluctuations for short...... than for long signals. The present study demonstrates how this effect can be captured by a nonlinear and active model of the cochlear in combination with a temporal integration stage. Since this cochlear model also accounts for fine structure and connected level dependent effects, it is superior...

  2. On the Appearance of Thresholds in the Dynamical Model of Star Formation

    Science.gov (United States)

    Elmegreen, Bruce G.

    2018-02-01

    The Kennicutt–Schmidt (KS) relationship between the surface density of the star formation rate (SFR) and the gas surface density has three distinct power laws that may result from one model in which gas collapses at a fixed fraction of the dynamical rate. The power-law slope is 1 when the observed gas has a characteristic density for detection, 1.5 for total gas when the thickness is about constant as in the main disks of galaxies, and 2 for total gas when the thickness is regulated by self-gravity and the velocity dispersion is about constant, as in the outer parts of spirals, dwarf irregulars, and giant molecular clouds. The observed scaling of the star formation efficiency (SFR per unit CO) with the dense gas fraction (HCN/CO) is derived from the KS relationship when one tracer (HCN) is on the linear part and the other (CO) is on the 1.5 part. Observations of a threshold density or column density with a constant SFR per unit gas mass above the threshold are proposed to be selection effects, as are observations of star formation in only the dense parts of clouds. The model allows a derivation of all three KS relations using the probability distribution function of density with no thresholds for star formation. Failed galaxies and systems with sub-KS SFRs are predicted to have gas that is dominated by an equilibrium warm phase where the thermal Jeans length exceeds the Toomre length. A squared relation is predicted for molecular gas-dominated young galaxies.

  3. When is rational to order a diagnostic test, or prescribe treatment: the threshold model as an explanation of practice variation.

    Science.gov (United States)

    Djulbegovic, Benjamin; van den Ende, Jef; Hamm, Robert M; Mayrhofer, Thomas; Hozo, Iztok; Pauker, Stephen G

    2015-05-01

    The threshold model represents an important advance in the field of medical decision-making. It is a linchpin between evidence (which exists on the continuum of credibility) and decision-making (which is a categorical exercise - we decide to act or not act). The threshold concept is closely related to the question of rational decision-making. When should the physician act, that is order a diagnostic test, or prescribe treatment? The threshold model embodies the decision theoretic rationality that says the most rational decision is to prescribe treatment when the expected treatment benefit outweighs its expected harms. However, the well-documented large variation in the way physicians order diagnostic tests or decide to administer treatments is consistent with a notion that physicians' individual action thresholds vary. We present a narrative review summarizing the existing literature on physicians' use of a threshold strategy for decision-making. We found that the observed variation in decision action thresholds is partially due to the way people integrate benefits and harms. That is, explanation of variation in clinical practice can be reduced to a consideration of thresholds. Limited evidence suggests that non-expected utility threshold (non-EUT) models, such as regret-based and dual-processing models, may explain current medical practice better. However, inclusion of costs and recognition of risk attitudes towards uncertain treatment effects and comorbidities may improve the explanatory and predictive value of the EUT-based threshold models. The decision when to act is closely related to the question of rational choice. We conclude that the medical community has not yet fully defined criteria for rational clinical decision-making. The traditional notion of rationality rooted in EUT may need to be supplemented by reflective rationality, which strives to integrate all aspects of medical practice - medical, humanistic and socio-economic - within a coherent

  4. Multifactorial Understanding of Ion Abundance in Tandem Mass Spectrometry Experiments.

    Science.gov (United States)

    Fazal, Zeeshan; Southey, Bruce R; Sweedler, Jonathan V; Rodriguez-Zas, Sandra L

    2013-01-29

    In a bottom-up shotgun approach, the proteins of a mixture are enzymatically digested, separated, and analyzed via tandem mass spectrometry. The mass spectra relating fragment ion intensities (abundance) to the mass-to-charge are used to deduce the amino acid sequence and identify the peptides and proteins. The variables that influence intensity were characterized using a multi-factorial mixed-effects model, a ten-fold cross-validation, and stepwise feature selection on 6,352,528 fragment ions from 61,543 peptide ions. Intensity was higher in fragment ions that did not have neutral mass loss relative to any mass loss or that had a +1 charge state. Peptide ions classified for proton mobility as non-mobile had lowest intensity of all mobility levels. Higher basic residue (arginine, lysine or histidine) counts in the peptide ion and low counts in the fragment ion were associated with lower fragment ion intensities. Higher counts of proline in peptide and fragment ions were associated with lower intensities. These results are consistent with the mobile proton theory. Opposite trends between peptide and fragment ion counts and intensity may be due to the different impact of factor under consideration at different stages of the MS/MS experiment or to the different distribution of observations across peptide and fragment ion levels. Presence of basic residues at all three positions next to the fragmentation site was associated with lower fragment ion intensity. The presence of proline proximal to the fragmentation site enhanced fragmentation and had the opposite trend when located distant from the site. A positive association between fragment ion intensity and presence of sulfur residues (cysteine and methionine) on the vicinity of the fragmentation site was identified. These results highlight the multi-factorial nature of fragment ion intensity and could improve the algorithms for peptide identification and the simulation in tandem mass spectrometry experiments.

  5. Beyond dysfunction and threshold-based classification: a multidimensional model of personality disorder diagnosis.

    Science.gov (United States)

    Bornstein, Robert F; Huprich, Steven K

    2011-06-01

    An alternative dimensional model of personality disorder (PD) diagnosis that addresses several difficulties inherent in the current DSM conceptualization of PDs (excessive PD overlap and comorbidity, use of arbitrary thresholds to distinguish normal from pathological personality functioning, failure to capture variations in the adaptative value of PD symptoms, and inattention to the impact of situational influences on PD-related behaviors) is outlined. The model uses a set of diagnostician-friendly strategies to render PD diagnosis in three steps: (1) the diagnostician assigns every patient a single dimensional rating of overall level of personality dysfunction on a 50-point continuum; (2) the diagnostician assigns separate intensity and impairment ratings for each PD dimension (e.g., narcissism, avoidance, dependency); and (3) the diagnostician lists any personality traits-including PD-related traits-that enhance adaptation and functioning (e.g., histrionic theatricality, obsessive attention to detail). Advantages of the proposed model for clinicians and clinical researchers are discussed.

  6. Study of Heat Flux Threshold and Perturbation Effect on Transport Barrier Formation Based on Bifurcation Model

    International Nuclear Information System (INIS)

    Chatthong, B.; Onjun, T.; Imbeaux, F.; Sarazin, Y.; Strugarek, A.; Picha, R.; Poolyarat, N.

    2011-06-01

    Full text: Formation of transport barrier in fusion plasma is studied using a simple one-field bistable S-curve bifurcation model. This model is characterized by an S-line with two stable branches corresponding to the low (L) and high (H) confinement modes, connected by an unstable branch. Assumptions used in this model are such that the reduction in anomalous transport is caused by v E velocity shear effect and also this velocity shear is proportional to pressure gradient. In this study, analytical and numerical approaches are used to obtain necessary conditions for transport barrier formation, i.e. the ratio of anomalous over neoclassical coefficients and heat flux thresholds which must be exceeded. Several profiles of heat sources are considered in this work including constant, Gaussian, and hyperbolic tangent forms. Moreover, the effect of perturbation in heat flux is investigated with respect to transport barrier formation

  7. An Efficient Code-Based Threshold Ring Signature Scheme with a Leader-Participant Model

    Directory of Open Access Journals (Sweden)

    Guomin Zhou

    2017-01-01

    Full Text Available Digital signature schemes with additional properties have broad applications, such as in protecting the identity of signers allowing a signer to anonymously sign a message in a group of signers (also known as a ring. While these number-theoretic problems are still secure at the time of this research, the situation could change with advances in quantum computing. There is a pressing need to design PKC schemes that are secure against quantum attacks. In this paper, we propose a novel code-based threshold ring signature scheme with a leader-participant model. A leader is appointed, who chooses some shared parameters for other signers to participate in the signing process. This leader-participant model enhances the performance because every participant including the leader could execute the decoding algorithm (as a part of signing process upon receiving the shared parameters from the leader. The time complexity of our scheme is close to Courtois et al.’s (2001 scheme. The latter is often used as a basis to construct other types of code-based signature schemes. Moreover, as a threshold ring signature scheme, our scheme is as efficient as the normal code-based ring signature.

  8. The impact of public debt on the twin imbalances in Europe: A threshold model

    Directory of Open Access Journals (Sweden)

    Šuliková Veronika

    2017-01-01

    Full Text Available Recent empirical research rejecting twin deficits in indebted countries and current account imbalances adjustment in Europe led to the idea to test the twin imbalances at different public debt-to-GDP intervals. The analysis covers 14 EU countries over the time period 1995-2012. A panel data threshold model with fixed effects estimates two debt-to-GDP thresholds (40.2% and 96.6%, which determine three debt-to-GDP intervals in the twin relationship. If public debtto-GDP is less than 40.2%, the model determines a negative relationship (twin divergence between budget balance and current account. Twin deficits (surpluses are confirmed exclusively if debt-to-GDP is in the interval between 40.2% and 96.6%. A twin divergence is also confirmed if public debt-to-GDP is more than 96.6% (e.g., as in Greece and Italy. The results confirm that increased indebtedness in European countries contributed to their current account imbalance adjustment.

  9. History-Based Response Threshold Model for Division of Labor in Multi-Agent Systems

    Science.gov (United States)

    Lee, Wonki; Kim, DaeEun

    2017-01-01

    Dynamic task allocation is a necessity in a group of robots. Each member should decide its own task such that it is most commensurate with its current state in the overall system. In this work, the response threshold model is applied to a dynamic foraging task. Each robot employs a task switching function based on the local task demand obtained from the surrounding environment, and no communication occurs between the robots. Each individual member has a constant-sized task demand history that reflects the global demand. In addition, it has response threshold values for all of the tasks and manages the task switching process depending on the stimuli of the task demands. The robot then determines the task to be executed to regulate the overall division of labor. This task selection induces a specialized tendency for performing a specific task and regulates the division of labor. In particular, maintaining a history of the task demands is very effective for the dynamic foraging task. Various experiments are performed using a simulation with multiple robots, and the results show that the proposed algorithm is more effective as compared to the conventional model. PMID:28555031

  10. Generalizing a complex model for gully threshold identification in the Mediterranean environment

    Science.gov (United States)

    Torri, D.; Borselli, L.; Iaquinta, P.; Iovine, G.; Poesen, J.; Terranova, O.

    2012-04-01

    Among the physical processes leading to land degradation, soil erosion by water is the most important and gully erosion may contribute, at places, to 70% of the total soil loss. Nevertheless, gully erosion has often been neglected in water soil erosion modeling, whilst more prominence has been given to rill and interrill erosion. Both to facilitate the processing by agricultural machinery and to take advantage of all the arable land, gullies are commonly removed at each crop cycle, with significant soil losses due to the repeated excavation of the channel by the successive rainstorm. When the erosive forces of overland flow exceed the strength of the soil particles to detachment and displacement, water erosion occurs and usually a channel is formed. As runoff is proportional to the local catchment area, a relationship between local slope, S, and contributing area, A, is supposed to exists. A "geomorphologic threshold" scheme is therefore suitable to interpret the physical process of gully initiation: accordingly, a gully is formed when a hydraulic threshold for incision exceeds the resistance of the soil particles to detachment and transport. Similarly, it appears reasonable that a gully ends when there is a reduction of slope, or the concentrated flow meets more resistant soil-vegetation complexes. This study aims to predict the location of the beginning of gullies in the Mediterranean environment, based on an evaluation of S and A by means of a mathematical model. For the identification of the areas prone to gully erosion, the model employs two empirical thresholds relevant to the head (Thead) and to the end (Tend) of the gullies (of the type SA^ b>Thead, SA^ bsituations (usually after abandonment), and c) databases for cropland have been merged. Selected data have been examined and interpreted mathematically to assess a value to be taken as a constant for the exponent "b" of the above equation. Literature data on the problem of topological thresholds Tend are

  11. A modeling approach to establish environmental flow threshold in ungauged semidiurnal tidal river

    Science.gov (United States)

    Akter, A.; Tanim, A. H.

    2018-03-01

    Due to shortage of flow monitoring data in ungauged semidiurnal river, 'environmental flow' (EF) determination based on its key component 'minimum low flow' is always difficult. For EF assessment this study selected a reach immediately after the Halda-Karnafuli confluence, a unique breeding ground for Indian Carp fishes of Bangladesh. As part of an ungauged tidal river, EF threshold establishment faces challenges in changing ecological paradigms with periodic change of tides and hydrologic alterations. This study describes a novel approach through modeling framework comprising hydrological, hydrodynamic and habitat simulation model. The EF establishment was conceptualized according to the hydrologic process of an ungauged semi-diurnal tidal regime in four steps. Initially, a hydrologic model coupled with a hydrodynamic model to simulate flow considering land use changes effect on streamflow, seepage loss of channel, friction dominated tidal decay as well as lack of long term flow characteristics. Secondly, to define hydraulic habitat feature, a statistical analysis on derived flow data was performed to identify 'habitat suitability'. Thirdly, to observe the ecological habitat behavior based on the identified hydrologic alteration, hydraulic habitat features were investigated. Finally, based on the combined habitat suitability index flow alteration and ecological response relationship was established. Then, the obtained EF provides a set of low flow indices of desired regime and thus the obtained discharge against maximum Weighted Usable Area (WUA) was defined as EF threshold for the selected reach. A suitable EF regime condition was obtained within flow range 25-30.1 m3/s i.e., around 10-12% of the mean annual runoff of 245 m3/s and these findings are within researchers' recommendation of minimum flow requirement. Additionally it was observed that tidal characteristics are dominant process in semi-diurnal regime. However, during the study period (2010-2015) the

  12. Theory of threshold phenomena

    International Nuclear Information System (INIS)

    Hategan, Cornel

    2002-01-01

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

  13. Effect of harmane on the convulsive threshold in epilepsy models in mice.

    Science.gov (United States)

    Aricioglu, Feyza; Yillar, Okan; Korcegez, Eylem; Berkman, Kemal

    2003-12-01

    The study investigated the activity of harmane on maximal electroshock seizures (MES) and seizures induced by pentilentetrazole (PTZ) in mice. Initial studies established convulsive current 50 (CC(50)) values or MES and effective dose 50 (ED(50)) for PTZ to produce seizures. Harmane (2.5, 5.0, or 10 mg/kg intraperitoneally) increased the threshold of seizures in MES dose-dependently. The convulsions produced by PTZ were decreased by the low dose of harmane (2.5 mg/kg), but the high dose of harmane (10 mg/kg) resulted in worse grade V convulsions followed by more lethality compared with PTZ alone. Therefore, harmane seems to be protective against grand mal seizures in the MES model but not against a petit mal seizure model (PTZ) in mice.

  14. A comparison of signal detection theory to the objective threshold/strategic model of unconscious perception.

    Science.gov (United States)

    Haase, Steven J; Fisk, Gary D

    2011-08-01

    A key problem in unconscious perception research is ruling out the possibility that weak conscious awareness of stimuli might explain the results. In the present study, signal detection theory was compared with the objective threshold/strategic model as explanations of results for detection and identification sensitivity in a commonly used unconscious perception task. In the task, 64 undergraduate participants detected and identified one of four briefly displayed, visually masked letters. Identification was significantly above baseline (i.e., proportion correct > .25) at the highest detection confidence rating. This result is most consistent with signal detection theory's continuum of sensory states and serves as a possible index of conscious perception. However, there was limited support for the other model in the form of a predicted "looker's inhibition" effect, which produced identification performance that was significantly below baseline. One additional result, an interaction between the target stimulus and type of mask, raised concerns for the generality of unconscious perception effects.

  15. Probabilistic transport models for plasma transport in the presence of critical thresholds: Beyond the diffusive paradigma)

    Science.gov (United States)

    Sánchez, R.; van Milligen, B. Ph.; Carreras, B. A.

    2005-05-01

    It is argued that the modeling of plasma transport in tokamaks may benefit greatly from extending the usual local paradigm to accommodate scale-free transport mechanisms. This can be done by combining Lévy distributions and a nonlinear threshold condition within the continuous time random walk concept. The advantages of this nonlocal, nonlinear extension are illustrated by constructing a simple particle density transport model that, as a result of these ideas, spontaneously exhibits much of nondiffusive phenomenology routinely observed in tokamaks. The fluid limit of the system shows that the kind of equations that are appropriate to capture these dynamics are based on fractional differential operators. In them, effective diffusivities and pinch velocities are found that are dynamically set by the system in response to the specific characteristics of the fueling source and external perturbations. This fact suggests some dramatic consequences for the extrapolation of these transport properties to larger size systems.

  16. Analytical connection between thresholds and immunization strategies of SIS model in random networks

    Science.gov (United States)

    Zhou, Ming-Yang; Xiong, Wen-Man; Liao, Hao; Wang, Tong; Wei, Zong-Wen; Fu, Zhong-Qian

    2018-05-01

    Devising effective strategies for hindering the propagation of viruses and protecting the population against epidemics is critical for public security and health. Despite a number of studies based on the susceptible-infected-susceptible (SIS) model devoted to this topic, we still lack a general framework to compare different immunization strategies in completely random networks. Here, we address this problem by suggesting a novel method based on heterogeneous mean-field theory for the SIS model. Our method builds the relationship between the thresholds and different immunization strategies in completely random networks. Besides, we provide an analytical argument that the targeted large-degree strategy achieves the best performance in random networks with arbitrary degree distribution. Moreover, the experimental results demonstrate the effectiveness of the proposed method in both artificial and real-world networks.

  17. Probabilistic transport models for plasma transport in the presence of critical thresholds: Beyond the diffusive paradigm

    International Nuclear Information System (INIS)

    Sanchez, R.; Milligen, B.Ph. van; Carreras, B.A.

    2005-01-01

    It is argued that the modeling of plasma transport in tokamaks may benefit greatly from extending the usual local paradigm to accommodate scale-free transport mechanisms. This can be done by combining Levy distributions and a nonlinear threshold condition within the continuous time random walk concept. The advantages of this nonlocal, nonlinear extension are illustrated by constructing a simple particle density transport model that, as a result of these ideas, spontaneously exhibits much of nondiffusive phenomenology routinely observed in tokamaks. The fluid limit of the system shows that the kind of equations that are appropriate to capture these dynamics are based on fractional differential operators. In them, effective diffusivities and pinch velocities are found that are dynamically set by the system in response to the specific characteristics of the fueling source and external perturbations. This fact suggests some dramatic consequences for the extrapolation of these transport properties to larger size systems

  18. The asymmetry of the impact of oil price shocks on economic activities: an application of the multivariate threshold model

    International Nuclear Information System (INIS)

    Bwo-Nung Huang; National Chia-Yi University; Hwang, M.J.; Hsiao-Ping Peng

    2005-01-01

    This paper applies the multivariate threshold model to investigate the impacts of an oil price change and its volatility on economic activities (changes in industrial production and real stock returns). The statistical test on the existence of a threshold effect indicates that a threshold value does exist. Using monthly data of the US, Canada, and Japan during the period from 1970 to 2002, we conclude: (i) the optimal threshold level seems to vary according to how an economy depends on imported oil and the attitude towards adopting energy-saving technology; (ii) an oil price change or its volatility has a limited impact on the economies if the change is below the threshold levels; (iii) if the change is above threshold levels, it appears that the change in oil price better explains macroeconomic variables than the volatility of the oil price; and (iv) if the change is above threshold levels, a change in oil price or its volatility explains the model better than the real interest rate. (author)

  19. Power thresholds for fast oscillatory instabilities in nuclear reactors: a simple mathematical model

    International Nuclear Information System (INIS)

    Suarez-Antola, Roberto; Uruguay)

    2007-01-01

    The cores of nuclear reactors, including its structural parts and cooling fluids, are complex mechanical systems able to vibrate in a set of normal modes and frequencies, if suitable perturbed. The cyclic variations in the strain state of the core materials may modify the reactivity, and thus thermal power, producing variations in strain due to thermal-elastic effects. If the variation of the temperature field is fast enough and if the Doppler Effect and other stabilizing prompt effects in the fuel are weak enough, a fast oscillatory instability could be produced, coupled with mechanical vibrations of small enough amplitude that they will not be excluded by the procedures of conventional mechanical design. After a careful discussion of the time scales of neutron kinetics, thermal-elastic and vibration phenomena, a simple lumped parameter mathematical model is constructed in order to study, in a first approximation, the stability of the reactor. An integro-differential equation for power kinetics is derived. Under certain conditions, fast oscillatory instabilities are found when power is greater than a threshold value, and the delay in the global power feedback loop is big enough. Approximate analytical formulae are given for the power threshold, critical delay and power oscillation frequency. It is shown that if prompt stabilizing fuel effects are strong enough, dangerous fast power oscillations due to mechanical thermal-nuclear coupling phenomena can not appear at any power level. (author)

  20. Threshold dynamics and ergodicity of an SIRS epidemic model with Markovian switching

    Science.gov (United States)

    Li, Dan; Liu, Shengqiang; Cui, Jing'an

    2017-12-01

    This paper studies the spread dynamics of a stochastic SIRS epidemic model with nonlinear incidence and varying population size, which is formulated as a piecewise deterministic Markov process. A threshold dynamic determined by the basic reproduction number R0 is established: the disease can be eradicated almost surely if R0 disease persists almost surely if R0 > 1. The existing method for analyzing ergodic behavior of population systems has been generalized. The modified method weakens the required conditions and has no limitations for both the number of environmental regimes and the dimension of the considered system. When R0 > 1, the existence of a stationary probability measure is obtained. Furthermore, with the modified method, the global attractivity of the Ω-limit set of the system and the convergence in total variation to the stationary measure are both demonstrated under a mild extra condition.

  1. Model for next-to-leading order threshold resummed form factors

    International Nuclear Information System (INIS)

    Aglietti, Ugo; Ricciardi, Giulia

    2004-01-01

    We present a model for next-to-leading order resummed threshold form factors based on a timelike coupling recently introduced in the framework of small x physics. Improved expressions for the form factors in N-space are obtained which are not plagued by Landau-pole singularities, as the included absorptive effects - usually neglected - act as regulators. The physical reason is that, because of faster decay of gluon jets, there is not enough resolution time to observe the Landau pole. Our form factors reduce to the standard ones when the absorptive parts related to the coupling are neglected. The inverse transform from N-space to x-space can be done directly without any prescription and we obtain analytical expressions for the form factors, which are well defined in all x-space

  2. Modeling habitat split: landscape and life history traits determine amphibian extinction thresholds.

    Directory of Open Access Journals (Sweden)

    Carlos Roberto Fonseca

    Full Text Available Habitat split is a major force behind the worldwide decline of amphibian populations, causing community change in richness and species composition. In fragmented landscapes, natural remnants, the terrestrial habitat of the adults, are frequently separated from streams, the aquatic habitat of the larvae. An important question is how this landscape configuration affects population levels and if it can drive species to extinction locally. Here, we put forward the first theoretical model on habitat split which is particularly concerned on how split distance - the distance between the two required habitats - affects population size and persistence in isolated fragments. Our diffusive model shows that habitat split alone is able to generate extinction thresholds. Fragments occurring between the aquatic habitat and a given critical split distance are expected to hold viable populations, while fragments located farther away are expected to be unoccupied. Species with higher reproductive success and higher diffusion rate of post-metamorphic youngs are expected to have farther critical split distances. Furthermore, the model indicates that negative effects of habitat split are poorly compensated by positive effects of fragment size. The habitat split model improves our understanding about spatially structured populations and has relevant implications for landscape design for conservation. It puts on a firm theoretical basis the relation between habitat split and the decline of amphibian populations.

  3. Modeling habitat split: landscape and life history traits determine amphibian extinction thresholds.

    Science.gov (United States)

    Fonseca, Carlos Roberto; Coutinho, Renato M; Azevedo, Franciane; Berbert, Juliana M; Corso, Gilberto; Kraenkel, Roberto A

    2013-01-01

    Habitat split is a major force behind the worldwide decline of amphibian populations, causing community change in richness and species composition. In fragmented landscapes, natural remnants, the terrestrial habitat of the adults, are frequently separated from streams, the aquatic habitat of the larvae. An important question is how this landscape configuration affects population levels and if it can drive species to extinction locally. Here, we put forward the first theoretical model on habitat split which is particularly concerned on how split distance - the distance between the two required habitats - affects population size and persistence in isolated fragments. Our diffusive model shows that habitat split alone is able to generate extinction thresholds. Fragments occurring between the aquatic habitat and a given critical split distance are expected to hold viable populations, while fragments located farther away are expected to be unoccupied. Species with higher reproductive success and higher diffusion rate of post-metamorphic youngs are expected to have farther critical split distances. Furthermore, the model indicates that negative effects of habitat split are poorly compensated by positive effects of fragment size. The habitat split model improves our understanding about spatially structured populations and has relevant implications for landscape design for conservation. It puts on a firm theoretical basis the relation between habitat split and the decline of amphibian populations.

  4. Two-dimensional threshold voltage model and design considerations for gate electrode work function engineered recessed channel nanoscale MOSFET: I

    International Nuclear Information System (INIS)

    Chaujar, Rishu; Kaur, Ravneet; Gupta, Mridula; Gupta, R S; Saxena, Manoj

    2009-01-01

    This paper discusses a threshold voltage model for novel device structure: gate electrode work function engineered recessed channel (GEWE-RC) nanoscale MOSFET, which combines the advantages of both RC and GEWE structures. In part I, the model accurately predicts (a) surface potential, (b) threshold voltage and (c) sub-threshold slope for single material gate recessed channel (SMG-RC) and GEWE-RC structures. Part II focuses on the development of compact analytical drain current model taking into account the transition regimes from sub-threshold to saturation. Furthermore, the drain conductance evaluation has also been obtained, reflecting relevance of the proposed device for analogue design. The analysis takes into account the effect of gate length and groove depth in order to develop a compact model suitable for device design. The analytical results predicted by the model confirm well with the simulated results. Results in part I also provide valuable design insights in the performance of nanoscale GEWE-RC MOSFET with optimum threshold voltage and negative junction depth (NJD), and hence serves as a tool to optimize important device and technological parameters for 40 nm technology

  5. Does more energy consumption bolster economic growth? An application of the nonlinear threshold regression model

    International Nuclear Information System (INIS)

    Huang, B.-N.; Hwang, M.J.; Yang, C.W.

    2008-01-01

    This paper separates data extending from 1971 to 2002 into the energy crisis period (1971-1980) and the post-energy crisis period (1981-2000) for 82 countries. The cross-sectional data (yearly averages) in these two periods are used to investigate the nonlinear relationships between energy consumption growth and economic growth when threshold variables are used. If threshold variables are higher than certain optimal threshold levels, there is either no significant relationship or else a significant negative relationship between energy consumption and economic growth. However, when these threshold variables are lower than certain optimal levels, there is a significant positive relationship between the two. In 48 out of the 82 countries studied, none of the four threshold variables is found to be higher than the optimal levels. It is inferred that these 48 countries should adopt a more aggressive energy policy. As for the other 34 countries, at least one threshold variable is higher than the optimal threshold level and thus these countries should adopt energy policies with varying degrees of conservation based on the number of threshold variables that are higher than the optimal threshold levels

  6. Influence of arousal threshold and depth of sleep on respiratory stability in man: analysis using a mathematical model.

    Science.gov (United States)

    Longobardo, G S; Evangelisti, C J; Cherniack, N S

    2009-12-01

    We examined the effect of arousals (shifts from sleep to wakefulness) on breathing during sleep using a mathematical model. The model consisted of a description of the fluid dynamics and mechanical properties of the upper airways and lungs, as well as a controller sensitive to arterial and brain changes in CO(2), changes in arterial oxygen, and a neural input, alertness. The body was divided into multiple gas store compartments connected by the circulation. Cardiac output was constant, and cerebral blood flows were sensitive to changes in O(2) and CO(2) levels. Arousal was considered to occur instantaneously when afferent respiratory chemical and neural stimulation reached a threshold value, while sleep occurred when stimulation fell below that value. In the case of rigid and nearly incompressible upper airways, lowering arousal threshold decreased the stability of breathing and led to the occurrence of repeated apnoeas. In more compressible upper airways, to maintain stability, increasing arousal thresholds and decreasing elasticity were linked approximately linearly, until at low elastances arousal thresholds had no effect on stability. Increased controller gain promoted instability. The architecture of apnoeas during unstable sleep changed with the arousal threshold and decreases in elasticity. With rigid airways, apnoeas were central. With lower elastances, apnoeas were mixed even with higher arousal thresholds. With very low elastances and still higher arousal thresholds, sleep consisted totally of obstructed apnoeas. Cycle lengths shortened as the sleep architecture changed from mixed apnoeas to total obstruction. Deeper sleep also tended to promote instability by increasing plant gain. These instabilities could be countered by arousal threshold increases which were tied to deeper sleep or accumulated aroused time, or by decreased controller gains.

  7. The minimal SUSY B−L model: simultaneous Wilson lines and string thresholds

    Energy Technology Data Exchange (ETDEWEB)

    Deen, Rehan; Ovrut, Burt A. [Department of Physics, University of Pennsylvania,209 South 33rd Street, Philadelphia, PA 19104-6396 (United States); Purves, Austin [Department of Physics, University of Pennsylvania,209 South 33rd Street, Philadelphia, PA 19104-6396 (United States); Department of Physics, Manhattanville College,2900 Purchase Street, Purchase, NY 10577 (United States)

    2016-07-08

    In previous work, we presented a statistical scan over the soft supersymmetry breaking parameters of the minimal SUSY B−L model. For specificity of calculation, unification of the gauge parameters was enforced by allowing the two ℤ{sub 3}×ℤ{sub 3} Wilson lines to have mass scales separated by approximately an order of magnitude. This introduced an additional “left-right” sector below the unification scale. In this paper, for three important reasons, we modify our previous analysis by demanding that the mass scales of the two Wilson lines be simultaneous and equal to an “average unification” mass 〈M{sub U}〉. The present analysis is 1) more “natural” than the previous calculations, which were only valid in a very specific region of the Calabi-Yau moduli space, 2) the theory is conceptually simpler in that the left-right sector has been removed and 3) in the present analysis the lack of gauge unification is due to threshold effects — particularly heavy string thresholds, which we calculate statistically in detail. As in our previous work, the theory is renormalization group evolved from 〈M{sub U}〉 to the electroweak scale — being subjected, sequentially, to the requirement of radiative B−L and electroweak symmetry breaking, the present experimental lower bounds on the B−L vector boson and sparticle masses, as well as the lightest neutral Higgs mass of ∼125 GeV. The subspace of soft supersymmetry breaking masses that satisfies all such constraints is presented and shown to be substantial.

  8. Considering a Threshold Energy in Reactive Transport Modeling of Microbially Mediated Redox Reactions in an Arsenic-Affected Aquifer

    Directory of Open Access Journals (Sweden)

    Marco Rotiroti

    2018-01-01

    Full Text Available The reductive dissolution of Fe-oxide driven by organic matter oxidation is the primary mechanism accepted for As mobilization in several alluvial aquifers. These processes are often mediated by microorganisms that require a minimum Gibbs energy available to conduct the reaction in order to sustain their life functions. Implementing this threshold energy in reactive transport modeling is rarely used in the existing literature. This work presents a 1D reactive transport modeling of As mobilization by the reductive dissolution of Fe-oxide and subsequent immobilization by co-precipitation in iron sulfides considering a threshold energy for the following terminal electron accepting processes: (a Fe-oxide reduction, (b sulfate reduction, and (c methanogenesis. The model is then extended by implementing a threshold energy on both reaction directions for the redox reaction pairs Fe(III reduction/Fe(II oxidation and methanogenesis/methane oxidation. The optimal threshold energy fitted in 4.50, 3.76, and 1.60 kJ/mol e− for sulfate reduction, Fe(III reduction/Fe(II oxidation, and methanogenesis/methane oxidation, respectively. The use of models implementing bidirectional threshold energy is needed when a redox reaction pair can be transported between domains with different redox potentials. This may often occur in 2D or 3D simulations.

  9. Predictors of the nicotine reinforcement threshold, compensation, and elasticity of demand in a rodent model of nicotine reduction policy*

    Science.gov (United States)

    Grebenstein, Patricia E.; Burroughs, Danielle; Roiko, Samuel A.; Pentel, Paul R.; LeSage, Mark G.

    2015-01-01

    Background The FDA is considering reducing the nicotine content in tobacco products as a population-based strategy to reduce tobacco addiction. Research is needed to determine the threshold level of nicotine needed to maintain smoking and the extent of compensatory smoking that could occur during nicotine reduction. Sources of variability in these measures across sub-populations also need to be identified so that policies can take into account the risks and benefits of nicotine reduction in vulnerable populations. Methods The present study examined these issues in a rodent nicotine self- administration model of nicotine reduction policy to characterize individual differences in nicotine reinforcement thresholds, degree of compensation, and elasticity of demand during progressive reduction of the unit nicotine dose. The ability of individual differences in baseline nicotine intake and nicotine pharmacokinetics to predict responses to dose reduction was also examined. Results Considerable variability in the reinforcement threshold, compensation, and elasticity of demand was evident. High baseline nicotine intake was not correlated with the reinforcement threshold, but predicted less compensation and less elastic demand. Higher nicotine clearance predicted low reinforcement thresholds, greater compensation, and less elastic demand. Less elastic demand also predicted lower reinforcement thresholds. Conclusions These findings suggest that baseline nicotine intake, nicotine clearance, and the essential value of nicotine (i.e. elasticity of demand) moderate the effects of progressive nicotine reduction in rats and warrant further study in humans. They also suggest that smokers with fast nicotine metabolism may be more vulnerable to the risks of nicotine reduction. PMID:25891231

  10. Predicting the threshold of pulse-train electrical stimuli using a stochastic auditory nerve model: the effects of stimulus noise.

    Science.gov (United States)

    Xu, Yifang; Collins, Leslie M

    2004-04-01

    The incorporation of low levels of noise into an electrical stimulus has been shown to improve auditory thresholds in some human subjects (Zeng et al., 2000). In this paper, thresholds for noise-modulated pulse-train stimuli are predicted utilizing a stochastic neural-behavioral model of ensemble fiber responses to bi-phasic stimuli. The neural refractory effect is described using a Markov model for a noise-free pulse-train stimulus and a closed-form solution for the steady-state neural response is provided. For noise-modulated pulse-train stimuli, a recursive method using the conditional probability is utilized to track the neural responses to each successive pulse. A neural spike count rule has been presented for both threshold and intensity discrimination under the assumption that auditory perception occurs via integration over a relatively long time period (Bruce et al., 1999). An alternative approach originates from the hypothesis of the multilook model (Viemeister and Wakefield, 1991), which argues that auditory perception is based on several shorter time integrations and may suggest an NofM model for prediction of pulse-train threshold. This motivates analyzing the neural response to each individual pulse within a pulse train, which is considered to be the brief look. A logarithmic rule is hypothesized for pulse-train threshold. Predictions from the multilook model are shown to match trends in psychophysical data for noise-free stimuli that are not always matched by the long-time integration rule. Theoretical predictions indicate that threshold decreases as noise variance increases. Theoretical models of the neural response to pulse-train stimuli not only reduce calculational overhead but also facilitate utilization of signal detection theory and are easily extended to multichannel psychophysical tasks.

  11. Partitioning into hazard subregions for regional peaks-over-threshold modeling of heavy precipitation

    Science.gov (United States)

    Carreau, J.; Naveau, P.; Neppel, L.

    2017-05-01

    The French Mediterranean is subject to intense precipitation events occurring mostly in autumn. These can potentially cause flash floods, the main natural danger in the area. The distribution of these events follows specific spatial patterns, i.e., some sites are more likely to be affected than others. The peaks-over-threshold approach consists in modeling extremes, such as heavy precipitation, by the generalized Pareto (GP) distribution. The shape parameter of the GP controls the probability of extreme events and can be related to the hazard level of a given site. When interpolating across a region, the shape parameter should reproduce the observed spatial patterns of the probability of heavy precipitation. However, the shape parameter estimators have high uncertainty which might hide the underlying spatial variability. As a compromise, we choose to let the shape parameter vary in a moderate fashion. More precisely, we assume that the region of interest can be partitioned into subregions with constant hazard level. We formalize the model as a conditional mixture of GP distributions. We develop a two-step inference strategy based on probability weighted moments and put forward a cross-validation procedure to select the number of subregions. A synthetic data study reveals that the inference strategy is consistent and not very sensitive to the selected number of subregions. An application on daily precipitation data from the French Mediterranean shows that the conditional mixture of GPs outperforms two interpolation approaches (with constant or smoothly varying shape parameter).

  12. Isobar model for gamma N -> eta N from threshold up to 1200 MeV

    CERN Document Server

    Tryasuchev, V A

    2002-01-01

    Precise results of the measurements of the gamma p -> eta p cross section near threshold at Mainz (Germany) as well as recent sensational results for the SIGMA-beam asymmetry and d sigma/d OMEGA of this process obtained at larger energies at Grenoble (France) were used to construct the isobar model for the processes gamma N -> eta N. The model includes six nucleon resonances: S sub 1 sub 1 (1535), S sub 1 sub 1 (1650), P sub 1 sub 1 (1440), P sub 1 sub 3 (1720), D sub 1 sub 3 (1520), and F sub 1 sub 5 (1680), whose properties are considered. Large positive experimental value of the SIGMA asymmetry for the processes gamma p -> eta p at small angles was reproduced with F sub 1 sub 5 (1680) and P sub 1 sub 3 (1720) resonances. Both S sub 1 sub 1 (1535) and S sub 1 sub 1 (1650) resonances must be included to describe the energy dependence of total cross section. The available data for the electromagnetic amplitudes of the excitation of resonances on protons and neutrons were adopted for the calculation for the ga...

  13. Vacation model for Markov machine repair problem with two heterogeneous unreliable servers and threshold recovery

    Science.gov (United States)

    Jain, Madhu; Meena, Rakesh Kumar

    2018-03-01

    Markov model of multi-component machining system comprising two unreliable heterogeneous servers and mixed type of standby support has been studied. The repair job of broken down machines is done on the basis of bi-level threshold policy for the activation of the servers. The server returns back to render repair job when the pre-specified workload of failed machines is build up. The first (second) repairman turns on only when the work load of N1 (N2) failed machines is accumulated in the system. The both servers may go for vacation in case when all the machines are in good condition and there are no pending repair jobs for the repairmen. Runge-Kutta method is implemented to solve the set of governing equations used to formulate the Markov model. Various system metrics including the mean queue length, machine availability, throughput, etc., are derived to determine the performance of the machining system. To provide the computational tractability of the present investigation, a numerical illustration is provided. A cost function is also constructed to determine the optimal repair rate of the server by minimizing the expected cost incurred on the system. The hybrid soft computing method is considered to develop the adaptive neuro-fuzzy inference system (ANFIS). The validation of the numerical results obtained by Runge-Kutta approach is also facilitated by computational results generated by ANFIS.

  14. Unified analytical threshold voltage model for non-uniformly doped dual metal gate fully depleted silicon-on-insulator MOSFETs

    Science.gov (United States)

    Rao, Rathnamala; Katti, Guruprasad; Havaldar, Dnyanesh S.; DasGupta, Nandita; DasGupta, Amitava

    2009-03-01

    The paper describes the unified analytical threshold voltage model for non-uniformly doped, dual metal gate (DMG) fully depleted silicon-on-insulator (FDSOI) MOSFETs based on the solution of 2D Poisson's equation. 2D Poisson's equation is solved analytically for appropriate boundary conditions using separation of variables technique. The solution is then extended to obtain the threshold voltage of the FDSOI MOSFET. The model is able to handle any kind of non-uniform doping, viz. vertical, lateral as well as laterally asymetric channel (LAC) profile in the SOI film in addition to the DMG structure. The analytical results are validated with the numerical simulations using the device simulator MEDICI.

  15. Determining the Threshold Value of Basil Yield Reduction and Evaluation of Water Uptake Models under Salinity Stress Condition

    OpenAIRE

    M. Sarai Tabrizi; H. Babazadeh; M. Homaee; F. Kaveh Kaveh; M. Parsinejad

    2016-01-01

    Introduction: Several mathematical models are being used for assessing the plant response to the salinity of the root zone. The salinity of the soil and water resources is a major challenge for agricultural sector in Iran. Several mathematical models have been developed for plant responses to the salinity stress. However, these models are often applicable in particular conditions. The objectives of this study were to evaluate the threshold value of Basil yield reduction, modeling Basil respon...

  16. Mirror structures above and below the linear instability threshold: Cluster observations, fluid model and hybrid simulations

    Directory of Open Access Journals (Sweden)

    V. Génot

    2009-02-01

    Full Text Available Using 5 years of Cluster data, we present a detailed statistical analysis of magnetic fluctuations associated with mirror structures in the magnetosheath. We especially focus on the shape of these fluctuations which, in addition to quasi-sinusoidal forms, also display deep holes and high peaks. The occurrence frequency and the most probable location of the various types of structures is discussed, together with their relation to local plasma parameters. While these properties have previously been correlated to the β of the plasma, we emphasize here the influence of the distance to the linear mirror instability threshold. This enables us to interpret the observations of mirror structures in a stable plasma in terms of bistability and subcritical bifurcation. The data analysis is supplemented by the prediction of a quasi-static anisotropic MHD model and hybrid numerical simulations in an expanding box aimed at mimicking the magnetosheath plasma. This leads us to suggest a scenario for the formation and evolution of mirror structures.

  17. No-Impact Threshold Values for NRAP's Reduced Order Models

    Energy Technology Data Exchange (ETDEWEB)

    Last, George V. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Murray, Christopher J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Brown, Christopher F. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Jordan, Preston D. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Sharma, Maneesh [West Virginia Univ., and National Energy Technlogy Lab., Morgantown, WV (United States)

    2013-02-01

    The purpose of this study was to develop methodologies for establishing baseline datasets and statistical protocols for determining statistically significant changes between background concentrations and predicted concentrations that would be used to represent a contamination plume in the Gen II models being developed by NRAP’s Groundwater Protection team. The initial effort examined selected portions of two aquifer systems; the urban shallow-unconfined aquifer system of the Edwards-Trinity Aquifer System (being used to develop the ROM for carbon-rock aquifers, and the a portion of the High Plains Aquifer (an unconsolidated and semi-consolidated sand and gravel aquifer, being used to development the ROM for sandstone aquifers). Threshold values were determined for Cd, Pb, As, pH, and TDS that could be used to identify contamination due to predicted impacts from carbon sequestration storage reservoirs, based on recommendations found in the EPA’s ''Unified Guidance for Statistical Analysis of Groundwater Monitoring Data at RCRA Facilities'' (US Environmental Protection Agency 2009). Results from this effort can be used to inform a ''no change'' scenario with respect to groundwater impacts, rather than the use of an MCL that could be significantly higher than existing concentrations in the aquifer.

  18. Validation of a thermal threshold nociceptive model in bearded dragons (Pogona vitticeps).

    Science.gov (United States)

    Couture, Émilie L; Monteiro, Beatriz P; Aymen, Jessica; Troncy, Eric; Steagall, Paulo V

    2017-05-01

    To validate a thermal threshold (TT) nociceptive model in bearded dragons (Pogona vitticeps) and to document TT changes after administration of morphine. A two-part randomized, blinded, controlled, experimental study. Five adult bearded dragons (242-396 g). A TT device delivered a ramped nociceptive stimulus (0.6 °C second -1 ) to the medial thigh until a response (leg kick/escape behavior) was observed or maximum (cut-off) temperature of 62 °C was reached. In phase I, period 1, six TT readings were determined at 20 minute intervals for evaluation of repeatability. Two of these readings were randomly assigned to be sham to assess specificity of the behavioral response. The same experiment was repeated 2 weeks later (period 2) to test reproducibility. In phase II, animals were administered either intramuscular morphine (10 mg kg -1 ) or saline 0.9%. TTs (maximum 68 °C) were determined before and 2, 4, 8, 12 and 24 hours after treatment administration. Data were analyzed using one-way anova (temporal changes and repeatability) and paired t tests (reproducibility and treatment comparisons) using Bonferroni correction (p dragons. TT nociceptive testing detected morphine administration and may be suitable for studying opioid regimens in bearded dragons. Copyright © 2017 Association of Veterinary Anaesthetists and American College of Veterinary Anesthesia and Analgesia. Published by Elsevier Ltd. All rights reserved.

  19. Modeling jointly low, moderate, and heavy rainfall intensities without a threshold selection

    KAUST Repository

    Naveau, Philippe; Huser, Raphaë l; Ribereau, Pierre; Hannart, Alexis

    2016-01-01

    context, this approach has at least two main drawbacks. First, working with excesses implies that a lot of observations (those below the chosen threshold) are completely disregarded. The range of precipitation is artificially shopped down into two pieces

  20. Reduction of structured population models to threshold-type delay equations and functional differential equations: A case study

    Energy Technology Data Exchange (ETDEWEB)

    Smith, H.L. (Arizona State Univ., Tempe (United States))

    1993-01-01

    It is shown by way of a simple example that certain structured population models lead naturally to differential delay equations of the threshold type and that these equations can be transformed in a natural way to functional differential equations. The model examined can be viewed as a model of competition between adults and juveniles of a single population. The results indicate the possibility that this competition leads to instability. 28 refs., 2 figs.

  1. La productividad multifactorial: concepto, medición y significado..

    OpenAIRE

    Enrique Hernández Laos

    2007-01-01

    En la bibliografía empírica del crecimiento económico suele hacerse referencia a las llamadas “fuentes del crecimiento.” Ello implica la medición y conceptualización de la llamada productividad multifactorial, lo que no constituye una tarea sencilla. En este artículo se exponen algunos de los principales problemas para la medición de la productividad multifactorial, y se avanza en la discusión de su conceptualización con fines de análisis empírico del crecimiento de los países. Por último, se...

  2. Modeling direction discrimination thresholds for yaw rotations around an earth-vertical axis for arbitrary motion profiles.

    Science.gov (United States)

    Soyka, Florian; Giordano, Paolo Robuffo; Barnett-Cowan, Michael; Bülthoff, Heinrich H

    2012-07-01

    Understanding the dynamics of vestibular perception is important, for example, for improving the realism of motion simulation and virtual reality environments or for diagnosing patients suffering from vestibular problems. Previous research has found a dependence of direction discrimination thresholds for rotational motions on the period length (inverse frequency) of a transient (single cycle) sinusoidal acceleration stimulus. However, self-motion is seldom purely sinusoidal, and up to now, no models have been proposed that take into account non-sinusoidal stimuli for rotational motions. In this work, the influence of both the period length and the specific time course of an inertial stimulus is investigated. Thresholds for three acceleration profile shapes (triangular, sinusoidal, and trapezoidal) were measured for three period lengths (0.3, 1.4, and 6.7 s) in ten participants. A two-alternative forced-choice discrimination task was used where participants had to judge if a yaw rotation around an earth-vertical axis was leftward or rightward. The peak velocity of the stimulus was varied, and the threshold was defined as the stimulus yielding 75 % correct answers. In accordance with previous research, thresholds decreased with shortening period length (from ~2 deg/s for 6.7 s to ~0.8 deg/s for 0.3 s). The peak velocity was the determining factor for discrimination: Different profiles with the same period length have similar velocity thresholds. These measurements were used to fit a novel model based on a description of the firing rate of semi-circular canal neurons. In accordance with previous research, the estimates of the model parameters suggest that velocity storage does not influence perceptual thresholds.

  3. Modelling single shot damage thresholds of multilayer optics for high-intensity short-wavelength radiation sources

    NARCIS (Netherlands)

    Loch, R.A.; Sobierajski, R.; Louis, Eric; Bosgra, J.; Bosgra, J.; Bijkerk, Frederik

    2012-01-01

    The single shot damage thresholds of multilayer optics for highintensity short-wavelength radiation sources are theoretically investigated, using a model developed on the basis of experimental data obtained at the FLASH and LCLS free electron lasers. We compare the radiation hardness of commonly

  4. Modelling the Happiness Classification of Addicted, Addiction Risk, Threshold and Non-Addicted Groups on Internet Usage

    Science.gov (United States)

    Sapmaz, Fatma; Totan, Tarik

    2018-01-01

    The aim of this study is to model the happiness classification of university students--grouped as addicted, addiction risk, threshold and non-addicted to internet usage--with compatibility analysis on a map as happiness, average and unhappiness. The participants in this study were 400 university students from Turkey. According to the results of…

  5. A Violation of the Conditional Independence Assumption in the Two-High-Threshold Model of Recognition Memory

    Science.gov (United States)

    Chen, Tina; Starns, Jeffrey J.; Rotello, Caren M.

    2015-01-01

    The 2-high-threshold (2HT) model of recognition memory assumes that test items result in distinct internal states: they are either detected or not, and the probability of responding at a particular confidence level that an item is "old" or "new" depends on the state-response mapping parameters. The mapping parameters are…

  6. GUT scale threshold corrections in a complete supersymmetric SO(10) model: αs(MZ) versus proton lifetime

    International Nuclear Information System (INIS)

    Lucas, V.; Raby, S.

    1996-01-01

    We show that one-loop GUT scale threshold corrections to gauge couplings are a significant constraint on the GUT symmetry-breaking sector of the theory. The one-loop threshold corrections relate the prediction for α s (M Z ) to the proton lifetime. We have calculated these corrections in a new complete SO(10) SUSY GUT. The results are consistent with the low-energy measurement of α s (M Z ). We have also calculated the proton lifetime and branching ratios in this model. We show that proton decay rates provide a powerful test for theories of fermion masses. copyright 1996 The American Physical Society

  7. STATISTICAL MODELLING OF FDC AND RETURN PERIODS TO CHARACTERISE QDF AND DESIGN THRESHOLD OF HYDROLOGICAL EXTREMES

    Directory of Open Access Journals (Sweden)

    Charles Onyutha

    2012-01-01

    Full Text Available In this paper, firstly, flow duration curves (FDCs for hydrological extremes were calibrated for a range of aggregation levels and seasons to provide compressed statistical information for water resources management at selected temporal scales and seasons. Secondly, instead of the common approach of using return periods, T (years for deriving discharge duration frequency (QDF relationships, the method of using exceedance frequencies, E (% was introduced so as to provide answer to important question like, what is the streamflow at a given aggregation level and selected E (%? Thirdly, the concept of estimated design threshold (EDT was introduced and proposed for consideration in the risk analysis for design of water resources structures. This study was based on the long daily discharge record for the period 1950 - 2008 at station 1EF01 in Kenya, on the Nzoia river with watershed area of 12,676 km² located in the North Eastern quadrant of Lake Victoria Nile Sub Basin. In the statistical modelling of FDCs and T (years, suitable extreme value distributions (EVD were selected and calibrated to fit nearly independent high flows and low flows. The FDCs and T-curves were used to determine the EDT. The FDCs were used to model the QDF relationships. To derive QDF relationships of hydrological extremes, for a given range of aggregation levels, extreme value analysis (EVA was carried out and suitable EVD selected. Next was the calibration of parameters of the EVD and analysis of relationship between the model parameters and aggregation levels. Finally, smooth mathematical relationships were derived using little but acceptable modifications to the model parameters. Such constructed QDF relationships can be used for various applications to estimate cumulative volumes of water available during droughts or floods at various aggregation levels or E (% of hydrological extremes. The EDT when obtained for a range of aggregation levels can also be used to understand

  8. STATISTICAL MODELLING OF FDC AND RETURN PERIODS TO CHARACTERISE QDF AND DESIGN THRESHOLD OF HYDROLOGICAL EXTREMES

    Directory of Open Access Journals (Sweden)

    Charles Onyutha

    2012-12-01

    Full Text Available In this paper, firstly, flow duration curves (FDCs for hydrological extremes were calibrated for a range of aggregation levels and seasons to provide compressed statistical information for water resources management at selected temporal scales and seasons. Secondly, instead of the common approach of using return periods, T (years for deriving discharge duration frequency (QDF relationships, the method of using exceedance frequencies, E (% was introduced so as to provide answer to important question like, what is the streamflow at a given aggregation level and selected E (%?. Thirdly, the concept of estimated design threshold (EDT was introduced and proposed for consideration in the risk analysis for design of water resources structures. This study was based on the long daily discharge record for the period 1950 – 2008 at station 1EF01 in Kenya, on the Nzoia river with watershed area of 12,676 km2 located in the North Eastern quadrant of Lake Victoria Nile Sub Basin. In the statistical modeling of FDCs and T (years, suitable extreme value distributions (EVD were selected and calibrated to fit nearly independent high flows and low flows. The FDCs and T-curves were used to determine the EDT. The FDCs were used to model the QDF relationships. To derive QDF relationships of hydrological extremes, for a given range of aggregation levels, extreme value analysis (EVA was carried out and suitable EVD selected. Next was the calibration of parameters of the EVD and analysis of relationship between the model parameters and aggregation levels. Finally, smooth mathematical relationships were derived using little but acceptable modifications to the model parameters. Such constructed QDF relationships can be used for various applications to estimate cumulative volumes of water available during droughts or floods at various aggregation levels or E (% of hydrological extremes. The EDT when obtained for a range of aggregation levels can also be used to

  9. Irreversible mean-field model of the critical behavior of charge-density waves below the threshold for sliding

    Science.gov (United States)

    Sornette, Didier

    1993-05-01

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

  10. Genetic parameters for direct and maternal calving ease in Walloon dairy cattle based on linear and threshold models.

    Science.gov (United States)

    Vanderick, S; Troch, T; Gillon, A; Glorieux, G; Gengler, N

    2014-12-01

    Calving ease scores from Holstein dairy cattle in the Walloon Region of Belgium were analysed using univariate linear and threshold animal models. Variance components and derived genetic parameters were estimated from a data set including 33,155 calving records. Included in the models were season, herd and sex of calf × age of dam classes × group of calvings interaction as fixed effects, herd × year of calving, maternal permanent environment and animal direct and maternal additive genetic as random effects. Models were fitted with the genetic correlation between direct and maternal additive genetic effects either estimated or constrained to zero. Direct heritability for calving ease was approximately 8% with linear models and approximately 12% with threshold models. Maternal heritabilities were approximately 2 and 4%, respectively. Genetic correlation between direct and maternal additive effects was found to be not significantly different from zero. Models were compared in terms of goodness of fit and predictive ability. Criteria of comparison such as mean squared error, correlation between observed and predicted calving ease scores as well as between estimated breeding values were estimated from 85,118 calving records. The results provided few differences between linear and threshold models even though correlations between estimated breeding values from subsets of data for sires with progeny from linear model were 17 and 23% greater for direct and maternal genetic effects, respectively, than from threshold model. For the purpose of genetic evaluation for calving ease in Walloon Holstein dairy cattle, the linear animal model without covariance between direct and maternal additive effects was found to be the best choice. © 2014 Blackwell Verlag GmbH.

  11. A Jackson network model and threshold policy for joint optimization of energy and delay in multi-hop wireless networks

    KAUST Repository

    Xia, Li

    2014-11-20

    This paper studies the joint optimization problem of energy and delay in a multi-hop wireless network. The optimization variables are the transmission rates, which are adjustable according to the packet queueing length in the buffer. The optimization goal is to minimize the energy consumption of energy-critical nodes and the packet transmission delay throughout the network. In this paper, we aim at understanding the well-known decentralized algorithms which are threshold based from a different research angle. By using a simplified network model, we show that we can adopt the semi-open Jackson network model and study this optimization problem in closed form. This simplified network model further allows us to establish some significant optimality properties. We prove that the system performance is monotonic with respect to (w.r.t.) the transmission rate. We also prove that the threshold-type policy is optimal, i.e., when the number of packets in the buffer is larger than a threshold, transmit with the maximal rate (power); otherwise, no transmission. With these optimality properties, we develop a heuristic algorithm to iteratively find the optimal threshold. Finally, we conduct some simulation experiments to demonstrate the main idea of this paper.

  12. A Jackson network model and threshold policy for joint optimization of energy and delay in multi-hop wireless networks

    KAUST Repository

    Xia, Li; Shihada, Basem

    2014-01-01

    This paper studies the joint optimization problem of energy and delay in a multi-hop wireless network. The optimization variables are the transmission rates, which are adjustable according to the packet queueing length in the buffer. The optimization goal is to minimize the energy consumption of energy-critical nodes and the packet transmission delay throughout the network. In this paper, we aim at understanding the well-known decentralized algorithms which are threshold based from a different research angle. By using a simplified network model, we show that we can adopt the semi-open Jackson network model and study this optimization problem in closed form. This simplified network model further allows us to establish some significant optimality properties. We prove that the system performance is monotonic with respect to (w.r.t.) the transmission rate. We also prove that the threshold-type policy is optimal, i.e., when the number of packets in the buffer is larger than a threshold, transmit with the maximal rate (power); otherwise, no transmission. With these optimality properties, we develop a heuristic algorithm to iteratively find the optimal threshold. Finally, we conduct some simulation experiments to demonstrate the main idea of this paper.

  13. Evaluation of the pentylenetetrazole seizure threshold test in epileptic mice as surrogate model for drug testing against pharmacoresistant seizures.

    Science.gov (United States)

    Töllner, Kathrin; Twele, Friederike; Löscher, Wolfgang

    2016-04-01

    Resistance to antiepileptic drugs (AEDs) is a major problem in epilepsy therapy, so that development of more effective AEDs is an unmet clinical need. Several rat and mouse models of epilepsy with spontaneous difficult-to-treat seizures exist, but because testing of antiseizure drug efficacy is extremely laborious in such models, they are only rarely used in the development of novel AEDs. Recently, the use of acute seizure tests in epileptic rats or mice has been proposed as a novel strategy for evaluating novel AEDs for increased antiseizure efficacy. In the present study, we compared the effects of five AEDs (valproate, phenobarbital, diazepam, lamotrigine, levetiracetam) on the pentylenetetrazole (PTZ) seizure threshold in mice that were made epileptic by pilocarpine. Experiments were started 6 weeks after a pilocarpine-induced status epilepticus. At this time, control seizure threshold was significantly lower in epileptic than in nonepileptic animals. Unexpectedly, only one AED (valproate) was less effective to increase seizure threshold in epileptic vs. nonepileptic mice, and this difference was restricted to doses of 200 and 300 mg/kg, whereas the difference disappeared at 400mg/kg. All other AEDs exerted similar seizure threshold increases in epileptic and nonepileptic mice. Thus, induction of acute seizures with PTZ in mice pretreated with pilocarpine does not provide an effective and valuable surrogate method to screen drugs for antiseizure efficacy in a model of difficult-to-treat chronic epilepsy as previously suggested from experiments with this approach in rats. Copyright © 2016 Elsevier Inc. All rights reserved.

  14. Does the Use of Multifactorial Training Methods Increase Practitioners' Competence?

    Science.gov (United States)

    Pittman, Corinthus Omari; Lawdis, Katina

    2017-01-01

    Skilled therapy practitioners are required by their governing associations to seek professional development per licensure requirements. These requirements facilitate clinical reasoning and confidence during patient care. There are limited online professional development workshops, especially ones that offer multifactorial training as an…

  15. Predictive value of testing for multiple genetic variants in multifactorial

    NARCIS (Netherlands)

    A.C.J.W. Janssens (Cécile); M.J. Khoury (Muin Joseph)

    2009-01-01

    textabstractMultifactorial diseases such as type 2 diabetes, osteoporosis, and cardiovascular disease are caused by a complex interplay of many genetic and nongenetic factors, each of which conveys a minor increase in the risk of disease. Unraveling the genetic origins of these diseases is

  16. Presbyastasis: a multifactorial cause of balance problems in the ...

    African Journals Online (AJOL)

    Presbyastasis: a multifactorial cause of balance problems in the elderly. C Rogers. Abstract. Presbyastasis is the result of age-related physiological changes in the three sensory systems and their central connections that contribute to balance. In all likelihood, presbyastasis is a complex condition involving many intertwined ...

  17. Vitamin D Deficiency : Universal Risk Factor for Multifactorial Diseases?

    NARCIS (Netherlands)

    de Borst, Martin H.; de Boer, Rudolf A.; Stolk, Ronald P.; Slaets, Joris P. J.; Wolffenbuttel, Bruce H. R.; Navis, Gerjan

    In the Western world, the majority of morbidity and mortality are caused by multifactorial diseases. Some risk factors are related to more than one type of disease. These so-called universal risk factors are highly relevant to the population, as reduction of universal risk factors may reduce the

  18. Adaptive optics for reduced threshold energy in femtosecond laser induced optical breakdown in water based eye model

    Science.gov (United States)

    Hansen, Anja; Krueger, Alexander; Ripken, Tammo

    2013-03-01

    In ophthalmic microsurgery tissue dissection is achieved using femtosecond laser pulses to create an optical breakdown. For vitreo-retinal applications the irradiance distribution in the focal volume is distorted by the anterior components of the eye causing a raised threshold energy for breakdown. In this work, an adaptive optics system enables spatial beam shaping for compensation of aberrations and investigation of wave front influence on optical breakdown. An eye model was designed to allow for aberration correction as well as detection of optical breakdown. The eye model consists of an achromatic lens for modeling the eye's refractive power, a water chamber for modeling the tissue properties, and a PTFE sample for modeling the retina's scattering properties. Aberration correction was performed using a deformable mirror in combination with a Hartmann-Shack-sensor. The influence of an adaptive optics aberration correction on the pulse energy required for photodisruption was investigated using transmission measurements for determination of the breakdown threshold and video imaging of the focal region for study of the gas bubble dynamics. The threshold energy is considerably reduced when correcting for the aberrations of the system and the model eye. Also, a raise in irradiance at constant pulse energy was shown for the aberration corrected case. The reduced pulse energy lowers the potential risk of collateral damage which is especially important for retinal safety. This offers new possibilities for vitreo-retinal surgery using femtosecond laser pulses.

  19. Predictors of the nicotine reinforcement threshold, compensation, and elasticity of demand in a rodent model of nicotine reduction policy.

    Science.gov (United States)

    Grebenstein, Patricia E; Burroughs, Danielle; Roiko, Samuel A; Pentel, Paul R; LeSage, Mark G

    2015-06-01

    The FDA is considering reducing the nicotine content in tobacco products as a population-based strategy to reduce tobacco addiction. Research is needed to determine the threshold level of nicotine needed to maintain smoking and the extent of compensatory smoking that could occur during nicotine reduction. Sources of variability in these measures across sub-populations also need to be identified so that policies can take into account the risks and benefits of nicotine reduction in vulnerable populations. The present study examined these issues in a rodent nicotine self-administration model of nicotine reduction policy to characterize individual differences in nicotine reinforcement thresholds, degree of compensation, and elasticity of demand during progressive reduction of the unit nicotine dose. The ability of individual differences in baseline nicotine intake and nicotine pharmacokinetics to predict responses to dose reduction was also examined. Considerable variability in the reinforcement threshold, compensation, and elasticity of demand was evident. High baseline nicotine intake was not correlated with the reinforcement threshold, but predicted less compensation and less elastic demand. Higher nicotine clearance predicted low reinforcement thresholds, greater compensation, and less elastic demand. Less elastic demand also predicted lower reinforcement thresholds. These findings suggest that baseline nicotine intake, nicotine clearance, and the essential value of nicotine (i.e. elasticity of demand) moderate the effects of progressive nicotine reduction in rats and warrant further study in humans. They also suggest that smokers with fast nicotine metabolism may be more vulnerable to the risks of nicotine reduction. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  20. "Getting Stuck" in Analogue Electronics: Threshold Concepts as an Explanatory Model

    Science.gov (United States)

    Harlow, A.; Scott, J.; Peter, M.; Cowie, B.

    2011-01-01

    Could the challenge of mastering threshold concepts be a potential factor that influences a student's decision to continue in electronics engineering? This was the question that led to a collaborative research project between educational researchers and the Faculty of Engineering in a New Zealand university. This paper deals exclusively with the…

  1. Account for the surface tension in hydraulic modeling of the weir with a sharp threshold

    Directory of Open Access Journals (Sweden)

    Medzveliya Manana Levanovna

    Full Text Available In the process of calculating and simulating water discharge in free channels it is necessary to know the flow features in case of small values of Reynolds and Weber numbers. The article considers the influence of viscosity and surface tension on the coefficient of a weir flow with sharp threshold. In the article the technique of carrying out experiments is stated, the equation is presented, which considers the influence of all factors: pressure over a spillway threshold, threshold height over a course bottom, speed of liquid, liquid density, dynamic viscosity, superficial tension, gravity acceleration, unit discharge, the width of the course. The surface tension and liquid density for the applied liquids changed a little. In the rectangular tray (6000x100x200 spillway with a sharp threshold was established. It is shown that weir flow coefficient depends on Reynolds number (in case Re < ~ 2000 and Webers number. A generalized expression for determining weir flow coefficient considering the influence of the forces of viscosity and surface tension is received.

  2. Genomic analysis of cow mortality and milk production using a threshold-linear model.

    Science.gov (United States)

    Tsuruta, S; Lourenco, D A L; Misztal, I; Lawlor, T J

    2017-09-01

    The objective of this study was to investigate the feasibility of genomic evaluation for cow mortality and milk production using a single-step methodology. Genomic relationships between cow mortality and milk production were also analyzed. Data included 883,887 (866,700) first-parity, 733,904 (711,211) second-parity, and 516,256 (492,026) third-parity records on cow mortality (305-d milk yields) of Holsteins from Northeast states in the United States. The pedigree consisted of up to 1,690,481 animals including 34,481 bulls genotyped with 36,951 SNP markers. Analyses were conducted with a bivariate threshold-linear model for each parity separately. Genomic information was incorporated as a genomic relationship matrix in the single-step BLUP. Traditional and genomic estimated breeding values (GEBV) were obtained with Gibbs sampling using fixed variances, whereas reliabilities were calculated from variances of GEBV samples. Genomic EBV were then converted into single nucleotide polymorphism (SNP) marker effects. Those SNP effects were categorized according to values corresponding to 1 to 4 standard deviations. Moving averages and variances of SNP effects were calculated for windows of 30 adjacent SNP, and Manhattan plots were created for SNP variances with the same window size. Using Gibbs sampling, the reliability for genotyped bulls for cow mortality was 28 to 30% in EBV and 70 to 72% in GEBV. The reliability for genotyped bulls for 305-d milk yields was 53 to 65% to 81 to 85% in GEBV. Correlations of SNP effects between mortality and 305-d milk yields within categories were the highest with the largest SNP effects and reached >0.7 at 4 standard deviations. All SNP regions explained less than 0.6% of the genetic variance for both traits, except regions close to the DGAT1 gene, which explained up to 2.5% for cow mortality and 4% for 305-d milk yields. Reliability for GEBV with a moderate number of genotyped animals can be calculated by Gibbs samples. Genomic

  3. Analytical threshold voltage modeling of ion-implanted strained-Si double-material double-gate (DMDG) MOSFETs

    Science.gov (United States)

    Goel, Ekta; Singh, Balraj; Kumar, Sanjay; Singh, Kunal; Jit, Satyabrata

    2017-04-01

    Two dimensional threshold voltage model of ion-implanted strained-Si double-material double-gate MOSFETs has been done based on the solution of two dimensional Poisson's equation in the channel region using the parabolic approximation method. Novelty of the proposed device structure lies in the amalgamation of the advantages of both the strained-Si channel and double-material double-gate structure with a vertical Gaussian-like doping profile. The effects of different device parameters (such as device channel length, gate length ratios, germanium mole fraction) and doping parameters (such as projected range, straggle parameter) on threshold voltage of the proposed structure have been investigated. It is observed that the subthreshold performance of the device can be improved by simply controlling the doping parameters while maintaining other device parameters constant. The modeling results show a good agreement with the numerical simulation data obtained by using ATLAS™, a 2D device simulator from SILVACO.

  4. The Measurement of the Relationship between Taiwan’s Bond Funds’ Net Flow and the Investment Risk -Threshold Autoregressive Model

    OpenAIRE

    Wo-Chiang Lee; Joe-Ming Lee

    2014-01-01

    This article applies the threshold autoregressive model to investigate the relationship between bond funds’ net flow and investment risk in Taiwan. Our empirical findings show that bond funds’ investors are concerned about the investment return and neglect the investment risk. In particular, when expanding the size of the bond funds, fund investors believe that the fund cannot lose any money on investment products. In order to satisfy investors, bond fund managers only target short-term retur...

  5. High-resolution modeling of thermal thresholds and environmental influences on coral bleaching for local and regional reef management.

    Science.gov (United States)

    Kumagai, Naoki H; Yamano, Hiroya

    2018-01-01

    Coral reefs are one of the world's most threatened ecosystems, with global and local stressors contributing to their decline. Excessive sea-surface temperatures (SSTs) can cause coral bleaching, resulting in coral death and decreases in coral cover. A SST threshold of 1 °C over the climatological maximum is widely used to predict coral bleaching. In this study, we refined thermal indices predicting coral bleaching at high-spatial resolution (1 km) by statistically optimizing thermal thresholds, as well as considering other environmental influences on bleaching such as ultraviolet (UV) radiation, water turbidity, and cooling effects. We used a coral bleaching dataset derived from the web-based monitoring system Sango Map Project, at scales appropriate for the local and regional conservation of Japanese coral reefs. We recorded coral bleaching events in the years 2004-2016 in Japan. We revealed the influence of multiple factors on the ability to predict coral bleaching, including selection of thermal indices, statistical optimization of thermal thresholds, quantification of multiple environmental influences, and use of multiple modeling methods (generalized linear models and random forests). After optimization, differences in predictive ability among thermal indices were negligible. Thermal index, UV radiation, water turbidity, and cooling effects were important predictors of the occurrence of coral bleaching. Predictions based on the best model revealed that coral reefs in Japan have experienced recent and widespread bleaching. A practical method to reduce bleaching frequency by screening UV radiation was also demonstrated in this paper.

  6. THE EFFECTS OF DIFFERENT MODELS OF SWIMMING TRAINING (DEFINED IN RELATION TO ANAEROBIC THRESHOLD ON THE INCREASE OF SWIM SPEED

    Directory of Open Access Journals (Sweden)

    Dragan Krivokapić

    2007-05-01

    Full Text Available On the sample of 32 fourth grade students of some Belgrade highs schools, who had the physical education classes carried out at the city’s swimming pools, an attempt was made to evaluate the effects of the two different programmes of swimming training in different intensity zones, defi ned relative to the anaerobic threshold. The examinees were divided into two groups out of 15 i.e. 17 participants who were not (according to statistics signifi cantly different in terms of average time and heart frequency during the 400 m swimming test and heart frequency and time measured after 50 m in the moment of reaching the anaerobic threshold. The fi rst training model consisted of swimming at the intensity level within the zone below anaerobic threshold, while the second model involved occasional swimming at a higher intensity sometimes surpassing the anaerobic threshold. The experimentalprogramme with both sub-groups lasted 8 weeks with 3 training sessions per week, 2 ‘of which we’re identical for both experimental groups, with the third one differing regarding the swimming intensity, this in the fi rst group being still in the zone below, and in the second group occasionally in the zone above the anaerobic threshold. The amount of training and the duration were the same in both programmes. The aim of the research , was to evaluate and to compare the effects of the two training models, using as the basic criteria possible changes of average time and heart frequency during the 400 m swimming test and heart frequency and time measured after 50 m in the moment of reaching the anaerobic thereshold. On the basis of the statistical analysis of the obtained data, it is possible to conclude that in both experimental groups there were statistically signifi cant changes of average values concerning all the physiological variables. Although the difference in effi ciency of applied experimental programmes is not defi ned, we can claim that both of experimental

  7. Effects of chlorpyrifos in freshwater model ecosystems: the influence of experimental conditions on ecotoxicological thresholds.

    Science.gov (United States)

    van Wijngaarden, René P A; Brock, Theo C M; Douglas, Mark T

    2005-10-01

    Three experiments were conducted to determine the impact of the insecticide chlorpyrifos (single applications of 0.01 to 10 microg AI litre(-1)) in plankton-dominated nutrient-rich microcosms. The microcosms (water volume approximately 14 litres) were established in the laboratory under temperature, light regimes and nutrient levels that simulated cool 'temperate' and warm 'Mediterranean' environmental conditions. The fate of chlorpyrifos in the water column was monitored and the effects on zooplankton, phytoplankton and community metabolism were followed for 4 or 5 weeks. The mean half-life (t1/2) of chlorpyrifos in the water of the test systems was 45 h under 'temperate' conditions and about 30 h under 'Mediterranean' environmental conditions. Microcrustaceans (cladocerans and copepod nauplii) were amongst the most sensitive organisms. All three experiments yielded community NOEC (no observed effect concentrations) of 0.1 microg AI litre(-1), similar to those derived from more complex outdoor studies. Above this threshold level, responses and effect chains, and time spans for recovery, differed between the experiments. For example, algal blooms as an indirect effect from the impact of exposure on grazing organisms were only observed under the 'Mediterranean' experimental conditions. The relatively simple indoor test system seems to be sufficient to provide estimates of safe threshold levels for the acute insecticidal effects of low-persistence compounds such as chlorpyrifos. The robustness of the community NOEC indicates that this threshold level is likely to be representative for many freshwater systems. Copyright (c) 2005 Society of Chemical Industry.

  8. Holes in the Bathtub: Water Table Dependent Services and Threshold Behavior in an Economic Model of Groundwater Extraction

    Science.gov (United States)

    Kirk-lawlor, N. E.; Edwards, E. C.

    2012-12-01

    In many groundwater systems, the height of the water table must be above certain thresholds for some types of surface flow to exist. Examples of flows that depend on water table elevation include groundwater baseflow to river systems, groundwater flow to wetland systems, and flow to springs. Meeting many of the goals of sustainable water resource management requires maintaining these flows at certain rates. Water resource management decisions invariably involve weighing tradeoffs between different possible usage regimes and the economic consequences of potential management choices are an important factor in these tradeoffs. Policies based on sustainability may have a social cost from forgoing present income. This loss of income may be worth bearing, but should be well understood and carefully considered. Traditionally, the economic theory of groundwater exploitation has relied on the assumption of a single-cell or "bathtub" aquifer model, which offers a simple means to examine complex interactions between water user and hydrologic system behavior. However, such a model assumes a closed system and does not allow for the simulation of groundwater outflows that depend on water table elevation (e.g. baseflow, springs, wetlands), even though those outflows have value. We modify the traditional single-cell aquifer model by allowing for outflows when the water table is above certain threshold elevations. These thresholds behave similarly to holes in a bathtub, where the outflow is a positive function of the height of the water table above the threshold and the outflow is lost when the water table drops below the threshold. We find important economic consequences to this representation of the groundwater system. The economic value of services provided by threshold-dependent outflows (including non-market value), such as ecosystem services, can be incorporated. The value of services provided by these flows may warrant maintaining the water table at higher levels than would

  9. Individual differences in gendered person perception: a multifactorial study

    OpenAIRE

    2008-01-01

    M.A. The psychological study of gender has evolved to comprise both dispositional and social cognitive perspectives (Morawski, 1987). Recent theoretical debates within these fields have centred on multifactorial and unifactorial conceptions of gendered factors (Spence, 1993), and the cognitive representation of gender (Howard & Hollander, 1997). This study aimed to investigate specific phenomena implicated in the above approaches. Firstly, it assessed the influence of using gender as a bas...

  10. Porcine skin visible lesion thresholds for near-infrared lasers including modeling at two pulse durations and spot sizes.

    Science.gov (United States)

    Cain, C P; Polhamus, G D; Roach, W P; Stolarski, D J; Schuster, K J; Stockton, K L; Rockwell, B A; Chen, Bo; Welch, A J

    2006-01-01

    With the advent of such systems as the airborne laser and advanced tactical laser, high-energy lasers that use 1315-nm wavelengths in the near-infrared band will soon present a new laser safety challenge to armed forces and civilian populations. Experiments in nonhuman primates using this wavelength have demonstrated a range of ocular injuries, including corneal, lenticular, and retinal lesions as a function of pulse duration. American National Standards Institute (ANSI) laser safety standards have traditionally been based on experimental data, and there is scant data for this wavelength. We are reporting minimum visible lesion (MVL) threshold measurements using a porcine skin model for two different pulse durations and spot sizes for this wavelength. We also compare our measurements to results from our model based on the heat transfer equation and rate process equation, together with actual temperature measurements on the skin surface using a high-speed infrared camera. Our MVL-ED50 thresholds for long pulses (350 micros) at 24-h postexposure are measured to be 99 and 83 J cm(-2) for spot sizes of 0.7 and 1.3 mm diam, respectively. Q-switched laser pulses of 50 ns have a lower threshold of 11 J cm(-2) for a 5-mm-diam top-hat laser pulse.

  11. Regional Seismic Threshold Monitoring

    National Research Council Canada - National Science Library

    Kvaerna, Tormod

    2006-01-01

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

  12. Modeling on oxide dependent 2DEG sheet charge density and threshold voltage in AlGaN/GaN MOSHEMT

    Science.gov (United States)

    Panda, J.; Jena, K.; Swain, R.; Lenka, T. R.

    2016-04-01

    We have developed a physics based analytical model for the calculation of threshold voltage, two dimensional electron gas (2DEG) density and surface potential for AlGaN/GaN metal oxide semiconductor high electron mobility transistors (MOSHEMT). The developed model includes important parameters like polarization charge density at oxide/AlGaN and AlGaN/GaN interfaces, interfacial defect oxide charges and donor charges at the surface of the AlGaN barrier. The effects of two different gate oxides (Al2O3 and HfO2) are compared for the performance evaluation of the proposed MOSHEMT. The MOSHEMTs with Al2O3 dielectric have an advantage of significant increase in 2DEG up to 1.2 × 1013 cm-2 with an increase in oxide thickness up to 10 nm as compared to HfO2 dielectric MOSHEMT. The surface potential for HfO2 based device decreases from 2 to -1.6 eV within 10 nm of oxide thickness whereas for the Al2O3 based device a sharp transition of surface potential occurs from 2.8 to -8.3 eV. The variation in oxide thickness and gate metal work function of the proposed MOSHEMT shifts the threshold voltage from negative to positive realizing the enhanced mode operation. Further to validate the model, the device is simulated in Silvaco Technology Computer Aided Design (TCAD) showing good agreement with the proposed model results. The accuracy of the developed calculations of the proposed model can be used to develop a complete physics based 2DEG sheet charge density and threshold voltage model for GaN MOSHEMT devices for performance analysis.

  13. A threshold-voltage model for small-scaled GaAs nMOSFET with stacked high-k gate dielectric

    Science.gov (United States)

    Chaowen, Liu; Jingping, Xu; Lu, Liu; Hanhan, Lu; Yuan, Huang

    2016-02-01

    A threshold-voltage model for a stacked high-k gate dielectric GaAs MOSFET is established by solving a two-dimensional Poisson's equation in channel and considering the short-channel, DIBL and quantum effects. The simulated results are in good agreement with the Silvaco TCAD data, confirming the correctness and validity of the model. Using the model, impacts of structural and physical parameters of the stack high-k gate dielectric on the threshold-voltage shift and the temperature characteristics of the threshold voltage are investigated. The results show that the stacked gate dielectric structure can effectively suppress the fringing-field and DIBL effects and improve the threshold and temperature characteristics, and on the other hand, the influence of temperature on the threshold voltage is overestimated if the quantum effect is ignored. Project supported by the National Natural Science Foundation of China (No. 61176100).

  14. A threshold-voltage model for small-scaled GaAs nMOSFET with stacked high-k gate dielectric

    International Nuclear Information System (INIS)

    Liu Chaowen; Xu Jingping; Liu Lu; Lu Hanhan; Huang Yuan

    2016-01-01

    A threshold-voltage model for a stacked high-k gate dielectric GaAs MOSFET is established by solving a two-dimensional Poisson's equation in channel and considering the short-channel, DIBL and quantum effects. The simulated results are in good agreement with the Silvaco TCAD data, confirming the correctness and validity of the model. Using the model, impacts of structural and physical parameters of the stack high-k gate dielectric on the threshold-voltage shift and the temperature characteristics of the threshold voltage are investigated. The results show that the stacked gate dielectric structure can effectively suppress the fringing-field and DIBL effects and improve the threshold and temperature characteristics, and on the other hand, the influence of temperature on the threshold voltage is overestimated if the quantum effect is ignored. (paper)

  15. Finance-growth nexus: Insights from an application of threshold regression model to Malaysia's dual financial system

    Directory of Open Access Journals (Sweden)

    Alaa Alaabed

    2016-06-01

    Full Text Available The purpose of this paper is to test the growing converging views regarding the destabilizing and growth-halting impact of interest-based debt financial system. The views are as advocated by the followers of Keynes and Hyman Minsky and those of Islam. Islam discourages interest rate based debt financing as it considers it not very conducive to productive activities and human solidarity. Likewise, since the onset of the crisis of 2007/2008, calls by skeptics of mainstream capitalism have been renewed. The paper applies a threshold regression model to Malaysian data and finds that the relationship between growth and financial development is non-linear. A threshold is estimated, after which credit expansion negatively impacts GDP growth. While the post-threshold negative relationship is found to be statistically significant, the estimated positive relationship at lower levels of financial development is insignificant. The findings provide support to the above views and are hoped to guide monetary authorities to better growth-promoting policy-making.

  16. Cavitation thresholds of contrast agents in an in vitro human clot model exposed to 120-kHz ultrasound.

    Science.gov (United States)

    Gruber, Matthew J; Bader, Kenneth B; Holland, Christy K

    2014-02-01

    Ultrasound contrast agents (UCAs) can be employed to nucleate cavitation to achieve desired bioeffects, such as thrombolysis, in therapeutic ultrasound applications. Effective methods of enhancing thrombolysis with ultrasound have been examined at low frequencies (cavitation thresholds for two UCAs exposed to 120-kHz ultrasound. A commercial ultrasound contrast agent (Definity(®)) and echogenic liposomes were investigated to determine the acoustic pressure threshold for ultraharmonic (UH) and broadband (BB) generation using an in vitro flow model perfused with human plasma. Cavitation emissions were detected using two passive receivers over a narrow frequency bandwidth (540-900 kHz) and a broad frequency bandwidth (0.54-1.74 MHz). UH and BB cavitation thresholds occurred at the same acoustic pressure (0.3 ± 0.1 MPa, peak to peak) and were found to depend on the sensitivity of the cavitation detector but not on the nucleating contrast agent or ultrasound duty cycle.

  17. An immuno-epidemiological model with threshold delay: a study of the effects of multiple exposures to a pathogen.

    Science.gov (United States)

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

    2015-01-01

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

  18. Evaluation on the cost-effective threshold of osteoporosis treatment on elderly women in China using discrete event simulation model.

    Science.gov (United States)

    Ni, W; Jiang, Y

    2017-02-01

    This study used a simulation model to determine the cost-effective threshold of fracture risk to treat osteoporosis among elderly Chinese women. Osteoporosis treatment is cost-effective among average-risk women who are at least 75 years old and above-average-risk women who are younger than 75 years old. Aging of the Chinese population is imposing increasing economic burden of osteoporosis. This study evaluated the cost-effectiveness of osteoporosis treatment among the senior Chinese women population. A discrete event simulation model using age-specific probabilities of hip fracture, clinical vertebral fracture, wrist fracture, humerus fracture, and other fracture; costs (2015 US dollars); and quality-adjusted life years (QALYs) was used to assess the cost-effectiveness of osteoporosis treatment. Incremental cost-effectiveness ratio (ICER) was calculated. The willingness to pay (WTP) for a QALY in China was compared with the calculated ICER to decide the cost-effectiveness. To determine the absolute 10-year hip fracture probability at which the osteoporosis treatment became cost-effective, average age-specific probabilities for all fractures were multiplied by a relative risk (RR) that was systematically varied from 0 to 10 until the WTP threshold was observed for treatment relative to no intervention. Sensitivity analyses were also performed to evaluate the impacts from WTP and annual treatment costs. In baseline analysis, simulated ICERs were higher than the WTP threshold among Chinese women younger than 75, but much lower than the WTP among the older population. Sensitivity analyses indicated that cost-effectiveness could vary due to a higher WTP threshold or a lower annual treatment cost. A 30 % increase in WTP or a 30 % reduction in annual treatment costs will make osteoporosis treatment cost-effective for Chinese women population from 55 to 85. The current study provides evidence that osteoporosis treatment is cost-effective among a subpopulation of

  19. SEMICONDUCTOR DEVICES: Two-dimensional threshold voltage analytical model of DMG strained-silicon-on-insulator MOSFETs

    Science.gov (United States)

    Jin, Li; Hongxia, Liu; Bin, Li; Lei, Cao; Bo, Yuan

    2010-08-01

    For the first time, a simple and accurate two-dimensional analytical model for the surface potential variation along the channel in fully depleted dual-material gate strained-Si-on-insulator (DMG SSOI) MOSFETs is developed. We investigate the improved short channel effect (SCE), hot carrier effect (HCE), drain-induced barrier-lowering (DIBL) and carrier transport efficiency for the novel structure MOSFET. The analytical model takes into account the effects of different metal gate lengths, work functions, the drain bias and Ge mole fraction in the relaxed SiGe buffer. The surface potential in the channel region exhibits a step potential, which can suppress SCE, HCE and DIBL. Also, strained-Si and SOI structure can improve the carrier transport efficiency, with strained-Si being particularly effective. Further, the threshold voltage model correctly predicts a “rollup" in threshold voltage with decreasing channel length ratios or Ge mole fraction in the relaxed SiGe buffer. The validity of the two-dimensional analytical model is verified using numerical simulations.

  20. Modeling of damage generation mechanisms in silicon at energies below the displacement threshold

    International Nuclear Information System (INIS)

    Santos, Ivan; Marques, Luis A.; Pelaz, Lourdes

    2006-01-01

    We have used molecular dynamics simulation techniques to study the generation of damage in Si within the low-energy deposition regime. We have demonstrated that energy transfers below the displacement threshold can produce a significant amount of damage, usually neglected in traditional radiation damage calculations. The formation of amorphous pockets agrees with the thermal spike concept of local melting. However, we have found that the order-disorder transition is not instantaneous, but it requires some time to reach the appropriate kinetic-potential energy redistribution for melting. The competition between the rate of this energy redistribution and the energy diffusion to the surrounding atoms determines the amount of damage generated by a given deposited energy. Our findings explain the diverse damage morphology produced by ions of different masses

  1. Double Photoionization Near Threshold

    Science.gov (United States)

    Wehlitz, Ralf

    2007-01-01

    The threshold region of the double-photoionization cross section is of particular interest because both ejected electrons move slowly in the Coulomb field of the residual ion. Near threshold both electrons have time to interact with each other and with the residual ion. Also, different theoretical models compete to describe the double-photoionization cross section in the threshold region. We have investigated that cross section for lithium and beryllium and have analyzed our data with respect to the latest results in the Coulomb-dipole theory. We find that our data support the idea of a Coulomb-dipole interaction.

  2. Incorporation of the time aspect into the liability-threshold model for case-control-family data

    DEFF Research Database (Denmark)

    Cederkvist, Luise; Holst, Klaus K.; Andersen, Klaus K.

    2017-01-01

    to estimates that are difficult to interpret and are potentially biased. We incorporate the time aspect into the liability-threshold model for case-control-family data following the same approach that has been applied in the twin setting. Thus, the data are considered as arising from a competing risks setting...... approach using simulation studies and apply it in the analysis of two Danish register-based case-control-family studies: one on cancer diagnosed in childhood and adolescence, and one on early-onset breast cancer....

  3. [Threshold value for reimbursement of costs of new drugs: cost-effectiveness research and modelling are essential links].

    Science.gov (United States)

    Frederix, Geert W J; Hövels, Anke M; Severens, Johan L; Raaijmakers, Jan A M; Schellens, Jan H M

    2015-01-01

    There is increasing discussion in the Netherlands about the introduction of a threshold value for the costs per extra year of life when reimbursing costs of new drugs. The Medicines Committee ('Commissie Geneesmiddelen'), a division of the Netherlands National Healthcare Institute ('Zorginstituut Nederland'), advises on reimbursement of costs of new drugs. This advice is based upon the determination of therapeutic value of the drug and the results of economic evaluations. Mathematical models that predict future costs and effectiveness are often used in economic evaluations; these models can vary greatly in transparency and quality due to author assumptions. Standardisation of cost-effectiveness models is one solution to overcome the unwanted variation in quality. Discussions about the introduction of a threshold value can only be meaningful if all involved are adequately informed, and by high quality in cost-effectiveness research and, particularly, economic evaluations. Collaboration and discussion between medical specialists, patients or patient organisations, health economists and policy makers, both in development of methods and in standardisation, are essential to improve the quality of decision making.

  4. Linking neocortical, cognitive, and genetic variability in autism with alterations of brain plasticity: the Trigger-Threshold-Target model.

    Science.gov (United States)

    Mottron, Laurent; Belleville, Sylvie; Rouleau, Guy A; Collignon, Olivier

    2014-11-01

    The phenotype of autism involves heterogeneous adaptive traits (strengths vs. disabilities), different domains of alterations (social vs. non-social), and various associated genetic conditions (syndromic vs. nonsyndromic autism). Three observations suggest that alterations in experience-dependent plasticity are an etiological factor in autism: (1) the main cognitive domains enhanced in autism are controlled by the most plastic cortical brain regions, the multimodal association cortices; (2) autism and sensory deprivation share several features of cortical and functional reorganization; and (3) genetic mutations and/or environmental insults involved in autism all appear to affect developmental synaptic plasticity, and mostly lead to its upregulation. We present the Trigger-Threshold-Target (TTT) model of autism to organize these findings. In this model, genetic mutations trigger brain reorganization in individuals with a low plasticity threshold, mostly within regions sensitive to cortical reallocations. These changes account for the cognitive enhancements and reduced social expertise associated with autism. Enhanced but normal plasticity may underlie non-syndromic autism, whereas syndromic autism may occur when a triggering mutation or event produces an altered plastic reaction, also resulting in intellectual disability and dysmorphism in addition to autism. Differences in the target of brain reorganization (perceptual vs. language regions) account for the main autistic subgroups. In light of this model, future research should investigate how individual and sex-related differences in synaptic/regional brain plasticity influence the occurrence of autism. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.

  5. Effect of the Combined Use of Tramadol and Milnacipran on Pain Threshold in an Animal Model of Fibromyalgia

    Science.gov (United States)

    Song, Junhwa; Mun, Hyunil; Park, Keon Uk

    2009-01-01

    Background/Aims Acidic saline injections produce mechanical hyperresponsiveness in male Sprague-Dawley rats. We investigated the effect of milnacipran in conjunction with tramadol on the pain threshold in an acidic saline animal model of pain. Methods The left gastrocnemius muscle of 20 male rats was injected with 100 µL of saline at pH 4.0 under brief isoflurane anesthesia on days 0 and 5. Rats administered acidic saline injections were separated into four study subgroups. After determining the pre-drug pain threshold, rats were injected intraperitoneally with one of the following regimens; saline, milnacipran alone (60 mg/kg), milnacipran (40 mg/kg) plus tramadol (20 mg/kg), or milnacipran (40 mg/kg) plus tramadol (40 mg/kg). Paw withdrawal in response to pressure was measured at 30 min, 120 min, and 5 days after injection. Nociceptive thresholds, expressed in grams, were measured with a Dynamic Plantar Aesthesiometer (Ugo Basile, Italy) by applying increasing pressure to the right or left hind paw until the rat withdrew the paw. Results A potent antihyperalgesic effect was observed when tramadol and milnacipran were used in combination (injected paw, p=0.001; contralateral paw, p=0.012). This finding was observed only at 30 min after the combination treatment. Conclusions We observed potentiation of the antihyperalgesic effect when milnacipran and tramadol were administered in combination in an animal model of fibromyalgia. Further research is required to determine the efficacy of various combination treatments in fibromyalgia in humans. PMID:19543493

  6. Multifactorial analysis of fatigue scale among nurses in Poland

    Directory of Open Access Journals (Sweden)

    Kwiecień-Jaguś Katarzyna

    2016-01-01

    Full Text Available Significant progress in the field of nursing has contributed to the widening of range of functions and professional duties of nurses. More frequent lack of nursing personnel has an impact on negative reception of work, it decreases sense of professional satisfaction and increases the level of burden and fatigue. Methods. The study applied the non-experimental method – a descriptive comparative study without a control group. The data was collected on the basis of Polish-language version of a Japanese questionnaire. In order to evaluate the level of physical fatigue the pedometer was used. Results.158 respondents of a group of 160 were included in the statistical analysis. The study group was internally diversified. The research project assessed the usefulness of the multifactorial analysis in evaluating the main components of nursing fatigue. Multifactorial analysis has shown that mental fatigue concentrated with changes in activeness, motivation and physical fatigue are strongly correlated with age, professional experience and education. Conclusion. Nursing is a profession of a special character and mission. Regardless of the place of work, nursing staff should be given the possibility of pursuing their profession under conditions ensuring the sense of security and protecting them from harmful effects on health.

  7. Using a multifactorial approach to determine fall risk profiles in portuguese older adults.

    Science.gov (United States)

    Moniz-Pereira, Vera; Carnide, Filomena; Ramalho, Fátima; André, Helô; Machado, Maria; Santos-Rocha, Rita; Veloso, António P

    2013-01-01

    The aim of this study was to use a multifactorial approach to characterize episodic and recurrent fallers risk profiles in Portuguese older adults. To accomplish the mentioned purpose, 1416 Portuguese older adults above 65 years were tested with three different field measurements: 1) health and falls questionnaire; 2) Physical Activity questionnaire and 3) a set of functional fitness tests. The subjects were divided in three different groups according to fall prevalence: non-fallers, subjects who did not report any falls during the previous year, episodic fallers, those who reported to have fallen only once during the previous year, and recurrent fallers, the ones that fell twice or more times during the previous year. Episodic and Recurrent fallers risk profiles were established using multifactorial logistic regression models in order to avoid confounding effects between the variables. The results showed that age was not a risk factor for either episodic or recurrent falling. In addition, health parameters were shown to be the factors distinguishing recurrent from episodic fallers. This may imply that, comparing with episodic falls, recurrent falls are more associated with higher presence of chronic conditions and are less likely to occur due to external factors. Furthermore, being a woman, having fear of falling and lower functional fitness levels were determinant factors for both episodic and recurrent falls. It is also important to note that, although total physical activity was only related with episodic falling, promoting physical activity and exercise may be the easiest and cheapest way to improve functional fitness and health levels and therefore, its role in fall prevention should not be underestimated. The results of this study reinforce the importance of using a multifactorial approach, not only focusing on cognitive-behavioral factors, but also on promoting physical activity and healthy lifestyles, when assessing fall risk or planning an intervention

  8. Student’s mental model, misconceptions, troublesome knowledge, and threshold concept on thermochemistry with DToM-POE

    Science.gov (United States)

    Wiji, W.; Mulyani, S.

    2018-05-01

    The purpose of this study is to obtain a profile of students' mental models, misconceptions, troublesome knowledge, and threshold concept on thermochemistry. The subjects in this study were 35 students. The method used in this research was descriptive method with instruments Diagnostic Test of Mental Model - Prediction, Observation, and Explanation (DToM-POE). The results showed that the students' ability to predict, observe, and explain ΔH of neutralization reaction of NaOH with HCl was still lacking. Most students tended to memorize chemical concepts related to symbolic level and they did not understand the meaning of the symbols used. Furthermore, most students were unable to connect the results of observations at the macroscopic level with the symbolic level to determine ΔH of neutralization reaction of NaOH with HCl. Then, most students tended to give an explanation by a net ionic equation or a chemical reaction equation at the symbolic level when explaining ΔH of neutralization reaction at the submicroscopic level. In addition, there are seven misconceptions, three troublesome knowledges, and three threshold concepts held by students on thermochemistry.

  9. The restricted stochastic user equilibrium with threshold model: Large-scale application and parameter testing

    DEFF Research Database (Denmark)

    Rasmussen, Thomas Kjær; Nielsen, Otto Anker; Watling, David P.

    2017-01-01

    Equilibrium model (DUE), by combining the strengths of the Boundedly Rational User Equilibrium model and the Restricted Stochastic User Equilibrium model (RSUE). Thereby, the RSUET model reaches an equilibrated solution in which the flow is distributed according to Random Utility Theory among a consistently...... model improves the behavioural realism, especially for high congestion cases. Also, fast and well-behaved convergence to equilibrated solutions among non-universal choice sets is observed across different congestion levels, choice model scale parameters, and algorithm step sizes. Clearly, the results...... highlight that the RSUET outperforms the MNP SUE in terms of convergence, calculation time and behavioural realism. The choice set composition is validated by using 16,618 observed route choices collected by GPS devices in the same network and observing their reproduction within the equilibrated choice sets...

  10. An analytical model of SAGD process considering the effect of threshold pressure gradient

    Science.gov (United States)

    Morozov, P.; Abdullin, A.; Khairullin, M.

    2018-05-01

    An analytical model is proposed for the development of super-viscous oil deposits by the method of steam-assisted gravity drainage, taking into account the nonlinear filtration law with the limiting gradient. The influence of non-Newtonian properties of oil on the productivity of a horizontal well and the cumulative steam-oil ratio are studied. Verification of the proposed model based on the results of physical modeling of the SAGD process was carried out.

  11. A sequential threshold cure model for genetic analysis of time-to-event data

    DEFF Research Database (Denmark)

    Ødegård, J; Madsen, Per; Labouriau, Rodrigo S.

    2011-01-01

    In analysis of time-to-event data, classical survival models ignore the presence of potential nonsusceptible (cured) individuals, which, if present, will invalidate the inference procedures. Existence of nonsusceptible individuals is particularly relevant under challenge testing with specific...... pathogens, which is a common procedure in aquaculture breeding schemes. A cure model is a survival model accounting for a fraction of nonsusceptible individuals in the population. This study proposes a mixed cure model for time-to-event data, measured as sequential binary records. In a simulation study...... survival data were generated through 2 underlying traits: susceptibility and endurance (risk of dying per time-unit), associated with 2 sets of underlying liabilities. Despite considerable phenotypic confounding, the proposed model was largely able to distinguish the 2 traits. Furthermore, if selection...

  12. Determining the Threshold Value of Basil Yield Reduction and Evaluation of Water Uptake Models under Salinity Stress Condition

    Directory of Open Access Journals (Sweden)

    M. Sarai Tabrizi

    2016-10-01

    Full Text Available Introduction: Several mathematical models are being used for assessing the plant response to the salinity of the root zone. The salinity of the soil and water resources is a major challenge for agricultural sector in Iran. Several mathematical models have been developed for plant responses to the salinity stress. However, these models are often applicable in particular conditions. The objectives of this study were to evaluate the threshold value of Basil yield reduction, modeling Basil response to salinity and to evaluate the effectiveness of available mathematical models for the yield estimation of the Basil . Materials and Methods: The extensive experiments were conducted with 13 natural saline water treatments including 1.2, 1.8, 2, 2.2, 2.5, 2.8, 3, 3.5, 4, 5, 6, 8, and 10 dSm-1. Water salinity treatments were prepared by mixing Shoor River water with fresh water. In order to quantify the salinity effect on Basil yield, seven mathematical models including Maas and Hoffman (1977, van Genuchten and Hoffman (1984, Dirksen and Augustijn (1988, and Homaee et al., (2002 were used. One of the relatively recent methods for soil water content measurements is theta probes instrument. Theta probes instrument consists of four probes with 60 mm long and 3 mm diameter, a water proof container (probe structure, and a cable that links input and output signals to the data logger display. The advantages that have been attributed to this method are high precision and direct and rapid measurements in the field and greenhouse. The range of measurements is not limited like tensiometer and is from saturation to wilting point. In this study, Theta probes instrument was calibrated by weighing method for exact irrigation scheduling. Relative transpiration was calculated using daily soil water content changes. A coarse sand layer with 2 centimeters thick was used to decrease evaporation from the surface soil of the pots. Quantity comparison of the used models was done

  13. Multifactorial etiology of Torus mandibularis: study of twins.

    Science.gov (United States)

    Auškalnis, Adomas; Rutkūnas, Vygandas; Bernhardt, Olaf; Šidlauskas, Mantas; Šalomskienė, Loreta; Basevičienė, Nomeda

    2015-01-01

    The aim of this study is to investigate the multifactorial etiology of mandibular tori analyzing the influence of genetics, occlusal overload, various clinical variables and their interactions. Overall, plaster casts of 162 twins (81 twin pairs) were analyzed for the presence or absence of mandibular tori. Atypical wear facets on canine tips or incisors were recorded to diagnose bruxism. Angle Class, any kind of anterior open bite and positive, negative or flat curve of Wilson were recorded. Zygosity determination was carried out using a DNA test. Mandibular tori were found in 56.8% of the cases. In 93.6% of all monozygotic twin pairs both individuals had or did not have mandibular tori (κ=0.96±0.04; p<0.001), compared to 79.4% concordance of mandibular tori in dizygotic co-twins (κ=0.7±0.12; p<0.001). Prevalence of mandibular tori was significantly higher in the group of bruxers (67.5%) compared to non-bruxers (31.3%) (p<0.001). Significant association between mandibular tori and negative or flat curve of Wilson in the maxillary second premolars and first molars was found (OR=2.55, 95% CI (1.19-5.46), p=0.016). In all monozygotic bruxers, 97.1% showed concordance of mandibular tori presence in both co-twins compared to 78.9% dizygotic bruxers, and this difference is statistically significant (p=0.007). Our results suggest that the mandibular tori are of a multifactorial origin. Mandibular tori seem to have genetic predisposition, and may be associated with teeth grinding as well as with negative or flat CW in region of maxillary second premolar and first molar.

  14. Universal squash model for optical communications using linear optics and threshold detectors

    International Nuclear Information System (INIS)

    Fung, Chi-Hang Fred; Chau, H. F.; Lo, Hoi-Kwong

    2011-01-01

    Transmission of photons through open-air or optical fibers is an important primitive in quantum-information processing. Theoretical descriptions of this process often consider single photons as information carriers and thus fail to accurately describe experimental implementations where any number of photons may enter a detector. It has been a great challenge to bridge this big gap between theory and experiments. One powerful method for achieving this goal is by conceptually squashing the received multiphoton states to single-photon states. However, until now, only a few protocols admit a squash model; furthermore, a recently proven no-go theorem appears to rule out the existence of a universal squash model. Here we show that a necessary condition presumed by all existing squash models is in fact too stringent. By relaxing this condition, we find that, rather surprisingly, a universal squash model actually exists for many protocols, including quantum key distribution, quantum state tomography, Bell's inequality testing, and entanglement verification.

  15. Development of a Threshold Model to Predict Germination of Populus tomentosa Seeds after Harvest and Storage under Ambient Condition

    Science.gov (United States)

    Wang, Wei-Qing; Cheng, Hong-Yan; Song, Song-Quan

    2013-01-01

    Effects of temperature, storage time and their combination on germination of aspen (Populus tomentosa) seeds were investigated. Aspen seeds were germinated at 5 to 30°C at 5°C intervals after storage for a period of time under 28°C and 75% relative humidity. The effect of temperature on aspen seed germination could not be effectively described by the thermal time (TT) model, which underestimated the germination rate at 5°C and poorly predicted the time courses of germination at 10, 20, 25 and 30°C. A modified TT model (MTT) which assumed a two-phased linear relationship between germination rate and temperature was more accurate in predicting the germination rate and percentage and had a higher likelihood of being correct than the TT model. The maximum lifetime threshold (MLT) model accurately described the effect of storage time on seed germination across all the germination temperatures. An aging thermal time (ATT) model combining both the TT and MLT models was developed to describe the effect of both temperature and storage time on seed germination. When the ATT model was applied to germination data across all the temperatures and storage times, it produced a relatively poor fit. Adjusting the ATT model to separately fit germination data at low and high temperatures in the suboptimal range increased the models accuracy for predicting seed germination. Both the MLT and ATT models indicate that germination of aspen seeds have distinct physiological responses to temperature within a suboptimal range. PMID:23658654

  16. Threshold law for ionization cross sections in the Temkin-Poet model

    International Nuclear Information System (INIS)

    Macek, J.H.; Ihra, W.

    1997-01-01

    An integral representation of wave functions for the Temkin-Poet model of electron impact on atomic hydrogen is given. Approximate wave functions are evaluated analytically for large hyperradius to extract the ionization S-matrix element. An ionization cross section of the form exp[-aE -1/6 +bE 1/6 ], where a and b are positive constants, is derived. The exponential suppression of ionization for small E appears to be the quantum counterpart of the delayed onset of ionization in the classical theory for this model. copyright 1997 The American Physical Society

  17. Demystifying nuclear power: the linear non-threshold model and its use for evaluating radiation effects on living organisms

    Energy Technology Data Exchange (ETDEWEB)

    Ramos, Alexandre F.; Vasconcelos, Miguel F.; Vergueiro, Sophia M. C.; Lima, Suzylaine S., E-mail: alex.ramos@usp.br [Universidade de São Paulo (USP), SP (Brazil). Núcleo Interdisciplinar de Modelagem de Sistemas Complexos

    2017-07-01

    Recently, a new variable has been introduced on nuclear power expansion policy: public opinion. That variable challenges the nuclear community to develop new programs aiming to educate society sectors interested on energy generation and not necessarily familiarized with concepts of the nuclear eld. Here we approach this challenge by discussing how a misconception about the use of theories in science has misled the interpretation of the Chernobyl's accident consequences. That discussion have been presented for students from fields related with Environmental Sciences and Humanities and have helped to elucidate that an extrapolation such as the Linear Non-Threshold model is a hypothesis to be tested experimentally instead of a theoretical tool with predictive power. (author)

  18. Demystifying nuclear power: the linear non-threshold model and its use for evaluating radiation effects on living organisms

    International Nuclear Information System (INIS)

    Ramos, Alexandre F.; Vasconcelos, Miguel F.; Vergueiro, Sophia M. C.; Lima, Suzylaine S.

    2017-01-01

    Recently, a new variable has been introduced on nuclear power expansion policy: public opinion. That variable challenges the nuclear community to develop new programs aiming to educate society sectors interested on energy generation and not necessarily familiarized with concepts of the nuclear eld. Here we approach this challenge by discussing how a misconception about the use of theories in science has misled the interpretation of the Chernobyl's accident consequences. That discussion have been presented for students from fields related with Environmental Sciences and Humanities and have helped to elucidate that an extrapolation such as the Linear Non-Threshold model is a hypothesis to be tested experimentally instead of a theoretical tool with predictive power. (author)

  19. Performance of the SWEEP model affected by estimates of threshold friction velocity

    Science.gov (United States)

    The Wind Erosion Prediction System (WEPS) is a process-based model and needs to be verified under a broad range of climatic, soil, and management conditions. Occasional failure of the WEPS erosion submodel (Single-event Wind Erosion Evaluation Program or SWEEP) to simulate erosion in the Columbia Pl...

  20. Characterization of foreign exchange market using the threshold-dealer-model

    Science.gov (United States)

    Yamada, Kenta; Takayasu, Hideki; Takayasu, Misako

    2007-08-01

    We introduce a deterministic dealer model which implements most of the empirical laws, such as fat tails in the price change distributions, autocorrelation of price change and non-Poissonian intervals. We also clarify the causality between microscopic dealers’ dynamics and macroscopic market's empirical laws.

  1. Evolution of self-organized division of labor in a response threshold model

    NARCIS (Netherlands)

    Duarte, Ana; Pen, Ido; Keller, Laurent; Weissing, Franz J.

    Division of labor in social insects is determinant to their ecological success. Recent models emphasize that division of labor is an emergent property of the interactions among nestmates obeying to simple behavioral rules. However, the role of evolution in shaping these rules has been largely

  2. Threshold Dynamics of a Huanglongbing Model with Logistic Growth in Periodic Environments

    Directory of Open Access Journals (Sweden)

    Jianping Wang

    2014-01-01

    Full Text Available We analyze the impact of seasonal activity of psyllid on the dynamics of Huanglongbing (HLB infection. A new model about HLB transmission with Logistic growth in psyllid insect vectors and periodic coefficients has been investigated. It is shown that the global dynamics are determined by the basic reproduction number R0 which is defined through the spectral radius of a linear integral operator. If R0 1, then the disease persists. Numerical values of parameters of the model are evaluated taken from the literatures. Furthermore, numerical simulations support our analytical conclusions and the sensitive analysis on the basic reproduction number to the changes of average and amplitude values of the recruitment function of citrus are shown. Finally, some useful comments on controlling the transmission of HLB are given.

  3. Computational modeling of interventions and protective thresholds to prevent disease transmission in deploying populations.

    Science.gov (United States)

    Burgess, Colleen; Peace, Angela; Everett, Rebecca; Allegri, Buena; Garman, Patrick

    2014-01-01

    Military personnel are deployed abroad for missions ranging from humanitarian relief efforts to combat actions; delay or interruption in these activities due to disease transmission can cause operational disruptions, significant economic loss, and stressed or exceeded military medical resources. Deployed troops function in environments favorable to the rapid and efficient transmission of many viruses particularly when levels of protection are suboptimal. When immunity among deployed military populations is low, the risk of vaccine-preventable disease outbreaks increases, impacting troop readiness and achievement of mission objectives. However, targeted vaccination and the optimization of preexisting immunity among deployed populations can decrease the threat of outbreaks among deployed troops. Here we describe methods for the computational modeling of disease transmission to explore how preexisting immunity compares with vaccination at the time of deployment as a means of preventing outbreaks and protecting troops and mission objectives during extended military deployment actions. These methods are illustrated with five modeling case studies for separate diseases common in many parts of the world, to show different approaches required in varying epidemiological settings.

  4. Computational Modeling of Interventions and Protective Thresholds to Prevent Disease Transmission in Deploying Populations

    Directory of Open Access Journals (Sweden)

    Colleen Burgess

    2014-01-01

    Full Text Available Military personnel are deployed abroad for missions ranging from humanitarian relief efforts to combat actions; delay or interruption in these activities due to disease transmission can cause operational disruptions, significant economic loss, and stressed or exceeded military medical resources. Deployed troops function in environments favorable to the rapid and efficient transmission of many viruses particularly when levels of protection are suboptimal. When immunity among deployed military populations is low, the risk of vaccine-preventable disease outbreaks increases, impacting troop readiness and achievement of mission objectives. However, targeted vaccination and the optimization of preexisting immunity among deployed populations can decrease the threat of outbreaks among deployed troops. Here we describe methods for the computational modeling of disease transmission to explore how preexisting immunity compares with vaccination at the time of deployment as a means of preventing outbreaks and protecting troops and mission objectives during extended military deployment actions. These methods are illustrated with five modeling case studies for separate diseases common in many parts of the world, to show different approaches required in varying epidemiological settings.

  5. How are multifactorial beliefs about the role of genetics and behavior in cancer causation associated with cancer risk cognitions and emotions in the US population?

    Science.gov (United States)

    Hamilton, Jada G; Waters, Erika A

    2018-02-01

    People who believe that cancer has both genetic and behavioral risk factors have more accurate mental models of cancer causation and may be more likely to engage in cancer screening behaviors than people who do not hold such multifactorial causal beliefs. This research explored possible health cognitions and emotions that might produce such differences. Using nationally representative cross-sectional data from the US Health Information National Trends Survey (N = 2719), we examined whether endorsing a multifactorial model of cancer causation was associated with perceptions of risk and other cancer-related cognitions and affect. Data were analyzed using linear regression with jackknife variance estimation and procedures to account for the complex survey design and weightings. Bivariate and multivariable analyses indicated that people who endorsed multifactorial beliefs about cancer had higher absolute risk perceptions, lower pessimism about cancer prevention, and higher worry about harm from environmental toxins that could be ingested or that emanate from consumer products (Ps feelings of risk, but multivariable analyses suggested that this effect was accounted for by the negative affect associated with reporting a family history of cancer. Multifactorial beliefs were not associated with believing that everything causes cancer or that there are too many cancer recommendations to follow (Ps > .05). Holding multifactorial causal beliefs about cancer are associated with a constellation of risk perceptions, health cognitions, and affect that may motivate cancer prevention and detection behavior. Copyright © 2017 John Wiley & Sons, Ltd.

  6. The Cybersemiotic Model of Communication: An Evolutionary View on the Threshold between Semiosis and Informational Exchange

    Directory of Open Access Journals (Sweden)

    Søren Brier

    2008-07-01

    Full Text Available This paper discusses various suggestions for a philosophical framework for a trans-disciplinary information science or a semiotic doctrine. These are: the mechanical materialistic, the pan-informational, the Luhmanian second order cybernetic approach, Peircian biosemiotics and finally the pan-semiotic approach. The limitations of each are analysed. The conclusion is that we will not have to choose between either a cybernetic-informational or a semiotic approach. A combination of a Peircian-based biosemiotics with autopoiesis theory, second order cybernetics and information science is suggested in a five-levelled cybersemiotic framework. The five levels are 1 a level of Firstness, 2 a level of mechanical matter, energy and force as Secondness, 3 a cybernetic and thermodynamic level of information, 4 a level of sign games and 5 a level of conscious language games. These levels are then used to differentiate levels of information systems, sign and language games in human communication. In our model Maturana and Varela’s description of the logic of the living as autopoietic is accepted and expanded with Luhmann’s generalization of the concept of autopoiesis, to cover also to psychological and socio-communicative systems. Adding a Peircian concept of semiosis to Luhmann’s theory in the framework of biosemiotics enables us to view the interplay of mind and body as a sign play. I have in a previous publication (see list of references suggested the term “sign play” pertaining to exosemiotics processes between animals in the same species by stretching Wittgenstein's language concept into the animal world of signs. The new concept of intrasemiotics designates the semiosis of the interpenetration between biological and psychological autopoietic systems as Luhmann defines them in his theory. One could therefore view intrasemiotics as the interplay between Lorenz' biological defined motivations and Freud's Id, understood as the psychological aspect

  7. The CNP signal is able to silence a supra threshold neuronal model

    Directory of Open Access Journals (Sweden)

    Francesca eCamera

    2015-04-01

    Full Text Available Several experimental results published in the literature showed that weak pulsed magnetic fields affected the response of the central nervous system. However, the specific biological mechanisms that regulate the observed behaviors are still unclear and further scientific investigation is required. In this work we performed simulations on a neuronal network model exposed to a specific pulsed magnetic field signal that seems to be very effective in modulating the brain activity: the Complex Neuroelectromagnetic Pulse (CNP. Results show that CNP can silence the neurons of a feed-forward network for signal intensities that depend on the strength of the bias current, the endogenous noise level and the specific waveforms of the pulses.

  8. Comparison of Strategies and Incidence Thresholds for Vi Conjugate Vaccines Against Typhoid Fever: A Cost-effectiveness Modeling Study.

    Science.gov (United States)

    Lo, Nathan C; Gupta, Ribhav; Stanaway, Jeffrey D; Garrett, Denise O; Bogoch, Isaac I; Luby, Stephen P; Andrews, Jason R

    2018-02-12

    Typhoid fever remains a major public health problem globally. While new Vi conjugate vaccines hold promise for averting disease, the optimal programmatic delivery remains unclear. We aimed to identify the strategies and associated epidemiologic conditions under which Vi conjugate vaccines would be cost-effective. We developed a dynamic, age-structured transmission and cost-effectiveness model that simulated multiple vaccination strategies with a typhoid Vi conjugate vaccine from a societal perspective. We simulated 10-year vaccination programs with (1) routine immunization of infants (aged typhoid fever and defined strategies as highly cost-effective by using the definition of a low-income country (defined as a country with a gross domestic product of $1045 per capita). We defined incidence as the true number of clinically symptomatic people in the population per year. Vi conjugate typhoid vaccines were highly cost-effective when administered by routine immunization activities through the EPI in settings with an annual incidence of >50 cases/100000 (95% uncertainty interval, 40-75 cases) and when administered through the EPI plus a catch-up campaign in settings with an annual incidence of >130 cases/100000 (95% uncertainty interval, 50-395 cases). The incidence threshold was sensitive to the typhoid-related case-fatality rate, carrier contribution to transmission, vaccine characteristics, and country-specific economic threshold for cost-effectiveness. Typhoid Vi conjugate vaccines would be highly cost-effective in low-income countries in settings of moderate typhoid incidence (50 cases/100000 annually). These results were sensitive to case-fatality rates, underscoring the need to consider factors contributing to typhoid mortality (eg, healthcare access and antimicrobial resistance) in the global vaccination strategy. © The Author(s) 2018. Published by Oxford University Press for the Infectious Diseases Society of America.

  9. Elaborating on Threshold Concepts

    Science.gov (United States)

    Rountree, Janet; Robins, Anthony; Rountree, Nathan

    2013-01-01

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

  10. A threshold model for receptor tyrosine kinase signaling specificity and cell fate determination [version 1; referees: 4 approved

    Directory of Open Access Journals (Sweden)

    Allen Zinkle

    2018-06-01

    Full Text Available Upon ligand engagement, the single-pass transmembrane receptor tyrosine kinases (RTKs dimerize to transmit qualitatively and quantitatively different intracellular signals that alter the transcriptional landscape and thereby determine the cellular response. The molecular mechanisms underlying these fundamental events are not well understood. Considering recent insights into the structural biology of fibroblast growth factor signaling, we propose a threshold model for RTK signaling specificity in which quantitative differences in the strength/longevity of ligand-induced receptor dimers on the cell surface lead to quantitative differences in the phosphorylation of activation loop (A-loop tyrosines as well as qualitative differences in the phosphorylation of tyrosines mediating substrate recruitment. In this model, quantitative differences on A-loop tyrosine phosphorylation result in gradations in kinase activation, leading to the generation of intracellular signals of varying amplitude/duration. In contrast, qualitative differences in the pattern of tyrosine phosphorylation on the receptor result in the recruitment/activation of distinct substrates/intracellular pathways. Commensurate with both the dynamics of the intracellular signal and the types of intracellular pathways activated, unique transcriptional signatures are established. Our model provides a framework for engineering clinically useful ligands that can tune receptor dimerization stability so as to bias the cellular transcriptome to achieve a desired cellular output.

  11. The Effects Of Asymmetric Transmission Of Exchange Rate On Inflation In Iran: Application Of Threshold Models

    Directory of Open Access Journals (Sweden)

    Naghdi Yazdan

    2015-08-01

    Full Text Available Given the recent fluctuation in the exchange rate and the presence of several factors such as the various economy-political sanctions (mainly embargos on oil and banking, extreme volatility in different economic fields, and consequently the devaluation of national and public procurement -A landmark that is emanating from exchange rate fluctuation - two points should be noted: First, it is essential to review the effect of exchange rate fluctuation on macro economic variables such as inflation and to provide appropriate policies. Second, the existence of this condition provides the chance to study the relation between exchange rate and inflation in a non-linear and asymmetric method. Hence, the present study seeks to use TAR model and, on the basis of monthly time series data over the period March 2002 to March 2014, to analyze the cross-asymmetric and non-linear exchange rate on consumer price index (CPI in Iran. The results also show the presence of an asymmetric long-term relationship between these variables (exchange rate and CPI. Also, in the Iranian economy, the effect of negative shocks of exchange rate on inflation is more sustainable than the one from positive shocks.

  12. Tiny changes in local order identify the cluster formation threshold in model fluids with competing interactions.

    Science.gov (United States)

    Bomont, Jean-Marc; Costa, Dino; Bretonnet, Jean-Louis

    2017-06-14

    We use Monte Carlo simulations to carry out a thorough analysis of structural correlations arising in a relatively dense fluid of rigid spherical particles with prototype competing interactions (short-range attractive and long-range repulsive two-Yukawa model). As the attraction strength increases, we show that the local density of the fluid displays a tiny reversal of trend within specific ranges of interparticle distances, whereupon it decreases first and increases afterwards, passing through a local minimum. Particles involved in this trend display, accordingly, distinct behaviours: for a sufficiently weak attraction, they seem to contribute to the long-wave oscillations typically heralding the formation of patterns in such fluids; for a stronger attraction, after the reversal of the local density has occurred, they form an outer shell of neighbours stabilizing the existing aggregation seeds. Following the increment of attraction, precisely in correspondence of the local density reversal, the local peak developed in the structure factor at small wavevectors markedly rises, signalling-in agreement with recent structural criteria-the onset of a clustered state. A detailed cluster analysis of microscopic configurations fully validates this picture.

  13. Modeling warming predicts a physiological threshold for the extinction of the living fossil frog Calyptocephalella gayi.

    Science.gov (United States)

    Vidal, Marcela A; Novoa-Muñoz, Francisco; Werner, Enrique; Torres, Cristian; Nova, Ricardo

    2017-10-01

    Global climate change will have a greater impact on ectotherms in tropical and subtropical communities than at higher latitudes, because ambient temperatures are closer to the upper thermal limits of species. Amphibian species are highly dependent on external weather conditions, and the effect of global warming on these has been evaluated recently. The Great Chilean frog (Calyptocephalella gayi) is an endemic, monotypic species and genus whose conservation status is considered Vulnerable because of high extraction pressure for human consumption, lack of regulatory measures and comprehension by its consumers. Their populations have also declined due to the loss and destruction of their habitats. C. gayi has not been considered as an object of physiological study, so this large species is not known as one that can adapt to current environmental changes. In this study we analyze the thermoregulatory capacity and thermal efficiency of C. gayi to determine its potential for climatic adaptation. The results indicate that this species is strictly a thermal-conformer; its thermal efficiency and its ability to withstand high temperatures allow it to sustain itself under a climate change scenario, however, it has thermal constraints that do not allow it to withstand temperatures greater than 30°C. By modeling its ontogenetic conditions mathematically, we project that the larvae are not in danger, although there is a group of around 4% which is very close to 30°C, which is the highest temperature recorded for the species. However, about 40% of subadults and approximately 47% of adult frogs will not survive the change of ~7°C projected for the following 85 years, which will affect future generations. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Threshold dose for peripheral neuropathy following intraoperative radiotherapy (IORT) in a large animal model

    International Nuclear Information System (INIS)

    Kinsella, T.J.; DeLuca, A.M.; Barnes, M.; Anderson, W.; Terrill, R.; Sindelar, W.F.

    1991-01-01

    Radiation injury to peripheral nerve is a dose-limiting toxicity in the clinical application of intraoperative radiotherapy, particularly for pelvic and retroperitoneal tumors. Intraoperative radiotherapy-related peripheral neuropathy in humans receiving doses of 20-25 Gy is manifested as a mixed motor-sensory deficit beginning 6-9 months following treatment. In a previous experimental study of intraoperative radiotherapy-related neuropathy of the lumbro-sacral plexus, an approximate inverse linear relationship was reported between the intraoperative dose (20-75 Gy range) and the time to onset of hind limb paresis (1-12 mos following intraoperative radiotherapy). The principal histological lesion in irradiated nerve was loss of large nerve fibers and perineural fibrosis without significant vascular injury. Similar histological changes in irradiated nerves were found in humans. To assess peripheral nerve injury to lower doses of intraoperative radiotherapy in this same large animal model, groups of four adult American Foxhounds received doses of 10, 15, or 20 Gy to the right lumbro-sacral plexus and sciatic nerve using 9 MeV electrons. The left lumbro-sacral plexus and sciatic nerve were excluded from the intraoperative field to allow each animal to serve as its own control. Following treatment, a complete neurological exam, electromyogram, and nerve conduction studies were performed monthly for 1 year. Monthly neurological exams were performed in years 2 and 3 whereas electromyogram and nerve conduction studies were performed every 3 months during this follow-up period. With follow-up of greater than or equal to 42 months, no dog receiving 10 or 15 Gy IORT shows any clinical or laboratory evidence of peripheral nerve injury. However, all four dogs receiving 20 Gy developed right hind limb paresis at 8, 9, 9, and 12 mos following intraoperative radiotherapy

  15. Influence of regression model and initial intensity of an incremental test on the relationship between the lactate threshold estimated by the maximal-deviation method and running performance.

    Science.gov (United States)

    Santos-Concejero, Jordan; Tucker, Ross; Granados, Cristina; Irazusta, Jon; Bidaurrazaga-Letona, Iraia; Zabala-Lili, Jon; Gil, Susana María

    2014-01-01

    This study investigated the influence of the regression model and initial intensity during an incremental test on the relationship between the lactate threshold estimated by the maximal-deviation method and performance in elite-standard runners. Twenty-three well-trained runners completed a discontinuous incremental running test on a treadmill. Speed started at 9 km · h(-1) and increased by 1.5 km · h(-1) every 4 min until exhaustion, with a minute of recovery for blood collection. Lactate-speed data were fitted by exponential and polynomial models. The lactate threshold was determined for both models, using all the co-ordinates, excluding the first and excluding the first and second points. The exponential lactate threshold was greater than the polynomial equivalent in any co-ordinate condition (P performance and is independent of the initial intensity of the test.

  16. A software tool to model genetic regulatory networks. Applications to the modeling of threshold phenomena and of spatial patterning in Drosophila.

    Directory of Open Access Journals (Sweden)

    Rui Dilão

    Full Text Available We present a general methodology in order to build mathematical models of genetic regulatory networks. This approach is based on the mass action law and on the Jacob and Monod operon model. The mathematical models are built symbolically by the Mathematica software package GeneticNetworks. This package accepts as input the interaction graphs of the transcriptional activators and repressors of a biological process and, as output, gives the mathematical model in the form of a system of ordinary differential equations. All the relevant biological parameters are chosen automatically by the software. Within this framework, we show that concentration dependent threshold effects in biology emerge from the catalytic properties of genes and its associated conservation laws. We apply this methodology to the segment patterning in Drosophila early development and we calibrate the genetic transcriptional network responsible for the patterning of the gap gene proteins Hunchback and Knirps, along the antero-posterior axis of the Drosophila embryo. In this approach, the zygotically produced proteins Hunchback and Knirps do not diffuse along the antero-posterior axis of the embryo of Drosophila, developing a spatial pattern due to concentration dependent thresholds. This shows that patterning at the gap genes stage can be explained by the concentration gradients along the embryo of the transcriptional regulators.

  17. Does a population-based multi-factorial lifestyle intervention increase social inequality in dietary habits?

    DEFF Research Database (Denmark)

    Toft, Ulla; Jakobsen, Iris Marie; Aadahl, Mette

    2012-01-01

    To investigate whether the effect of an individualised multi-factorial lifestyle intervention on dietary habits differs across socioeconomic groups.......To investigate whether the effect of an individualised multi-factorial lifestyle intervention on dietary habits differs across socioeconomic groups....

  18. Cost-effectiveness of intensive multifactorial treatment compared with routine care for individuals with screen-detected Type 2 diabetes

    DEFF Research Database (Denmark)

    Tao, L; Wilson, E C F; Wareham, N J

    2015-01-01

    , falling to £37 500 over 30 years. The ICER fell below £30 000 only when the intervention cost was below £631 per patient: we estimated the cost at £981. Conclusion Given conventional thresholds of cost-effectiveness, the intensive treatment delivered in ADDITION was not cost-effective compared......Aims To examine the short- and long-term cost-effectiveness of intensive multifactorial treatment compared with routine care among people with screen-detected Type 2 diabetes. Methods Cost–utility analysis in ADDITION-UK, a cluster-randomized controlled trial of early intensive treatment in people...... at 3.5%). Adjusted incremental QALYs were 0.0000, – 0.0040, 0.0140 and 0.0465 over the same time horizons. Point estimate incremental cost-effectiveness ratios (ICERs) suggested that the intervention was not cost-effective although the ratio improved over time: the ICER over 10 years was £82 250...

  19. Performance Evaluation of Linear (ARMA and Threshold Nonlinear (TAR Time Series Models in Daily River Flow Modeling (Case Study: Upstream Basin Rivers of Zarrineh Roud Dam

    Directory of Open Access Journals (Sweden)

    Farshad Fathian

    2017-01-01

    Full Text Available Introduction: Time series models are generally categorized as a data-driven method or mathematically-based method. These models are known as one of the most important tools in modeling and forecasting of hydrological processes, which are used to design and scientific management of water resources projects. On the other hand, a better understanding of the river flow process is vital for appropriate streamflow modeling and forecasting. One of the main concerns of hydrological time series modeling is whether the hydrologic variable is governed by the linear or nonlinear models through time. Although the linear time series models have been widely applied in hydrology research, there has been some recent increasing interest in the application of nonlinear time series approaches. The threshold autoregressive (TAR method is frequently applied in modeling the mean (first order moment of financial and economic time series. Thise type of the model has not received considerable attention yet from the hydrological community. The main purposes of this paper are to analyze and to discuss stochastic modeling of daily river flow time series of the study area using linear (such as ARMA: autoregressive integrated moving average and non-linear (such as two- and three- regime TAR models. Material and Methods: The study area has constituted itself of four sub-basins namely, Saghez Chai, Jighato Chai, Khorkhoreh Chai and Sarogh Chai from west to east, respectively, which discharge water into the Zarrineh Roud dam reservoir. River flow time series of 6 hydro-gauge stations located on upstream basin rivers of Zarrineh Roud dam (located in the southern part of Urmia Lake basin were considered to model purposes. All the data series used here to start from January 1, 1997, and ends until December 31, 2011. In this study, the daily river flow data from January 01 1997 to December 31 2009 (13 years were chosen for calibration and data for January 01 2010 to December 31 2011

  20. Distributions of extreme bursts above thresholds in a fractional Lévy toy model of natural complexity.

    Science.gov (United States)

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

    2010-05-01

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

  1. Etiology of Balkan endemic nephropathy: A multifactorial disease?

    International Nuclear Information System (INIS)

    Toncheva, Draga; Dimitrov, Tzvetan; Stojanova, Stiliana

    1998-01-01

    Balkan endemic nephropathy (BEN) is of great clinical importance in the restricted areas of Bulgaria, Rumania, Croatia, Serbia, Bosnia and Herzegovina. So far, studies on the etiological factors for BEN have not discovered any single environmental causative agent of this puzzling disease. These data reject the possibility of a purely environmental causation of BEN. The pattern of BEN transmission in the risk families is not typical for single gene disorders. Extensive epidemiological and genetic studies disclose characteristics of multifactorial (polygenic) inheritance of BEN. The evidences of 'familial tendency', variation of the risk for BEN depending on the number of sick parents and the degree of relatedness; the development of BEN in individuals from at-risk families who were born in non-endemic areas; the data that disease is not found in the gypsy population and the expressions of 3q25 cytogenetic marker suggest that the genetic factors play an important role as causative factors in BEN development. The possible impact of environmental triggers on individuals genetically predisposed to BEN could be supposed by the following data: the cytogenetic results of the increased frequency of folate sensitive Fra sites, spontaneous or radiation-induced aberrations in several bands in BEN patients, the data from the detailed analysis of breaks in BEN patients and controls that generate structural chromosome aberrations; the occurrence of BEN in immigrants. Genetical epidemiological approaches to etiology and prevention of BEN are proposed. The predisposing genes for BEN could be genes localized in a region between 3q25-3q26; transforming growth factor-β (TGF-β), genetic heterogeneity of xenobiotic-metabolizing enzymes; defects in the host's immune system. The predisposing genes for BEN patients with urinary tract tumors could be germline mutations in tumor suppressor genes and acquired somatic mutations in oncogenes

  2. Comparisons of adaptive TIN modelling filtering method and threshold segmentation filtering method of LiDAR point cloud

    International Nuclear Information System (INIS)

    Chen, Lin; Fan, Xiangtao; Du, Xiaoping

    2014-01-01

    Point cloud filtering is the basic and key step in LiDAR data processing. Adaptive Triangle Irregular Network Modelling (ATINM) algorithm and Threshold Segmentation on Elevation Statistics (TSES) algorithm are among the mature algorithms. However, few researches concentrate on the parameter selections of ATINM and the iteration condition of TSES, which can greatly affect the filtering results. First the paper presents these two key problems under two different terrain environments. For a flat area, small height parameter and angle parameter perform well and for areas with complex feature changes, large height parameter and angle parameter perform well. One-time segmentation is enough for flat areas, and repeated segmentations are essential for complex areas. Then the paper makes comparisons and analyses of the results by these two methods. ATINM has a larger I error in both two data sets as it sometimes removes excessive points. TSES has a larger II error in both two data sets as it ignores topological relations between points. ATINM performs well even with a large region and a dramatic topology while TSES is more suitable for small region with flat topology. Different parameters and iterations can cause relative large filtering differences

  3. Lowered threshold energy for femtosecond laser induced optical breakdown in a water based eye model by aberration correction with adaptive optics.

    Science.gov (United States)

    Hansen, Anja; Géneaux, Romain; Günther, Axel; Krüger, Alexander; Ripken, Tammo

    2013-06-01

    In femtosecond laser ophthalmic surgery tissue dissection is achieved by photodisruption based on laser induced optical breakdown. In order to minimize collateral damage to the eye laser surgery systems should be optimized towards the lowest possible energy threshold for photodisruption. However, optical aberrations of the eye and the laser system distort the irradiance distribution from an ideal profile which causes a rise in breakdown threshold energy even if great care is taken to minimize the aberrations of the system during design and alignment. In this study we used a water chamber with an achromatic focusing lens and a scattering sample as eye model and determined breakdown threshold in single pulse plasma transmission loss measurements. Due to aberrations, the precise lower limit for breakdown threshold irradiance in water is still unknown. Here we show that the threshold energy can be substantially reduced when using adaptive optics to improve the irradiance distribution by spatial beam shaping. We found that for initial aberrations with a root-mean-square wave front error of only one third of the wavelength the threshold energy can still be reduced by a factor of three if the aberrations are corrected to the diffraction limit by adaptive optics. The transmitted pulse energy is reduced by 17% at twice the threshold. Furthermore, the gas bubble motions after breakdown for pulse trains at 5 kilohertz repetition rate show a more transverse direction in the corrected case compared to the more spherical distribution without correction. Our results demonstrate how both applied and transmitted pulse energy could be reduced during ophthalmic surgery when correcting for aberrations. As a consequence, the risk of retinal damage by transmitted energy and the extent of collateral damage to the focal volume could be minimized accordingly when using adaptive optics in fs-laser surgery.

  4. Multifactorial comparative proteomic study of cytochrome P450 2E1 function in chronic alcohol administration.

    Directory of Open Access Journals (Sweden)

    Yuan Wang

    Full Text Available With the use of iTRAQ technique, a multifactorial comparative proteomic study can be performed. In this study, to obtain an overview of ethanol, CYP2E1 and gender effects on liver injury and gain more insight into the underlying molecular mechanism, mouse liver proteomes were quantitatively analyzed using iTRAQ under eight conditions including mice of different genders, wild type versus CYP2E1 knockout, and normal versus alcohol diet. A series of statistical and bioinformatic analyses were explored to simplify and clarify multifactorial comparative proteomic data. First, with the Principle Component analysis, six proteins, CYP2E1, FAM25, CA3, BHMT, HIBADH and ECHS1, involved in oxidation reduction, energy and lipid metabolism and amino acid metabolism, were identified as the most differentially expressed gene products across all of the experimental conditions of our chronic alcoholism model. Second, hierarchical clustering analysis showed CYP2E1 knockout played a primary role in the overall differential protein expression compared with ethanol and gender factors. Furthermore, pair-wise multiple comparisons have revealed that the only significant expression difference lied in wild-type and CYP2E1 knockout mice both treated with ethanol. Third, K-mean clustering analysis indicated that the CYP2E1 knockout had the reverse effect on ethanol induced oxidative stress and lipid oxidation. More importantly, IPA analysis of proteomic data inferred that the gene expressions of two upstream regulators, NRF2 and PPARα, regulated by chronic alcohol feeding and CYP2E1 knockout, are involved in ethanol induced oxidative stress and lipid oxidation. The present study provides an effectively comprehensive data analysis strategy to compare multiple biological factors, contributing to biochemical effects of alcohol on the liver. The mass spectrometry proteomics data have been deposited to the ProteomeXchange with data set identifier of PXD000635.

  5. An Analytical Threshold Voltage Model of Fully Depleted (FD) Recessed-Source/Drain (Re-S/D) SOI MOSFETs with Back-Gate Control

    Science.gov (United States)

    Saramekala, Gopi Krishna; Tiwari, Pramod Kumar

    2016-10-01

    This paper presents an analytical threshold voltage model for back-gated fully depleted (FD), recessed-source drain silicon-on-insulator metal-oxide-semiconductor field-effect transistors (MOSFETs). Analytical surface potential models have been developed at front and back surfaces of the channel by solving the two-dimensional (2-D) Poisson's equation in the channel region with appropriate boundary conditions assuming a parabolic potential profile in the transverse direction of the channel. The strong inversion criterion is applied to the front surface potential as well as on the back one in order to find two separate threshold voltages for front and back channels of the device, respectively. The device threshold voltage has been assumed to be associated with the surface that offers a lower threshold voltage. The developed model was analyzed extensively for a variety of device geometry parameters like the oxide and silicon channel thicknesses, the thickness of the source/drain extension in the buried oxide, and the applied bias voltages with back-gate control. The proposed model has been validated by comparing the analytical results with numerical simulation data obtained from ATLAS™, a 2-D device simulator from SILVACO.

  6. What factors influence community-dwelling older people’s intent to undertake multifactorial fall prevention programs?

    Directory of Open Access Journals (Sweden)

    Hill KD

    2014-11-01

    Full Text Available Keith D Hill,1,2 Lesley Day,3 Terry P Haines4,5 1School of Physiotherapy and Exercise Science, Faculty of Health Sciences, Curtin University, Perth, WA, Australia; 2National Ageing Research Institute, Royal Melbourne Hospital, Parkville, VIC, Australia; 3Falls Prevention Research Unit, Monash Injury Research Institute, Monash University, VIC, Australia; 4Allied Health Research Unit, Southern Health, Cheltenham, VIC, Australia; 5Physiotherapy Department, Faculty of Medicine, Nursing, and Health Sciences, Monash University, VIC, Australia Purpose: To investigate previous, current, or planned participation in, and perceptions toward, multifactorial fall prevention programs such as those delivered through a falls clinic in the community setting, and to identify factors influencing older people’s intent to undertake these interventions.Design and methods: Community-dwelling people aged >70 years completed a telephone survey. Participants were randomly selected from an electronic residential telephone listing, but purposeful sampling was used to include equal numbers with and without common chronic health conditions associated with fall-related hospitalization. The survey included scenarios for fall prevention interventions, including assessment/multifactorial interventions, such as those delivered through a falls clinic. Participants were asked about previous exposure to, or intent to participate in, the interventions. A path model analysis was used to identify factors associated with intent to participate in assessment/multifactorial interventions.Results: Thirty of 376 participants (8.0% reported exposure to a multifactorial falls clinic-type intervention in the past 5 years, and 16.0% expressed intention to undertake this intervention. Of the 132 participants who reported one or more falls in the past 12 months, over one-third were undecided or disagreed that a falls clinic type of intervention would be of benefit to them. Four elements

  7. Measurements and modeling for examination of magnitudes and thresholds and transitions of cellular radio-protective mechanisms

    International Nuclear Information System (INIS)

    Leonard, B.

    2007-01-01

    Complete text of publication follows. Purpose: To provide results of dose and dose rate measurements, modeling and analysis for the high Radon 'inverse' dose-rate effect (IDRE), adaptive response (AR) , Bystander Effects (BE), Hyper-radiosensitivity and dose induced radioresistance (HRS/IRR) and the low LET IDRE. Methods: Radon progeny particle diameters decrease at high Radon levels, due to increased neutralization rates. Underground miners data are used to confirm lung dose effects. An adaptive response Microdose Model formulated from the microdose concepts of Feinendegen and his cohorts, is extended to include BE and applied to IDRE, AR and BE experimental data. Results: Analysis of underground miners data conclusively supports a factor of 4.3 in lung dose from increased deposition in the nasel passages, negating BE as cause of the Lubin et al (1995) high Radon lung cancer IDRE. This negates support of BE as major concern at domestic Radon levels and high LET galactic radiations for manned Mars mission. AR Microdose Model use for mammography X-rays shows single Specific Energy Hits, at very low dose rates to the cell nucleus, activates AR protection against spontaneous neoplastic transformations of a factor of 2 further supporting Redpath (2007) of no deleterious cancer risk from mammography X-rays and a dose/dose-rate coupling. IRR in HRS/IRR is from increased repair capability 'triggered' at a very low dose of 15 cGy. The 'triggering' is shown in low LET IDRE with G2/M checkpoint arrest. The correlation suggest IRR in both HRS/IRR and low LET IDRE dose and dose rate radio-protection are from the activation of same increased repair rate protective mechanisms i.e. dose/dose-rate coupling. In examination of LDR Brachytherapy, it's plausible the high excess post-treatment complications, especially for cervix cancer, compared to HDR Brachytherapy is from a high-radiosensitivity for the decaying permanent implant sources below the IDRE threshold with a possible

  8. A condition-based maintenance of a dependent degradation-threshold-shock model in a system with multiple degradation processes

    International Nuclear Information System (INIS)

    Caballé, N.C.; Castro, I.T.; Pérez, C.J.; Lanza-Gutiérrez, J.M.

    2015-01-01

    This paper proposes a condition-based maintenance strategy for a system subject to two dependent causes of failure: degradation and sudden shocks. The internal degradation is reflected by the presence of multiple degradation processes in the system. Degradation processes start at random times following a Non-homogeneous Poisson process and their growths are modelled by using a gamma process. When the deterioration level of a degradation process exceeds a predetermined value, we assume that a degradation failure occurs. Furthermore, the system is subject to sudden shocks that arrive at the system following a Doubly Stochastic Poisson Process. A sudden shock provokes the total breakdown of the system. Thus, the state of the system is evaluated at inspection times and different maintenance tasks can be carried out. If the system is still working at an inspection time, a preventive maintenance task is performed if the deterioration level of a degradation process exceeds a certain threshold. A corrective maintenance task is performed if the system is down at an inspection time. A preventive (corrective) maintenance task implies the replacement of the system by a new one. Under this maintenance strategy, the expected cost rate function is obtained. A numerical example illustrates the analytical results. - Highlights: • A condition-based maintenance model is proposed. • Two dependent causes of failure are considered: deterioration and external shocks. • Deterioration is given by multiple degradation processes growing by a gamma process. • The initiation of degradation processes follows a Non-homogeneous Poisson process. • External shocks arrive at the system by using a Doubly Stochastic Poisson Process

  9. A simple algorithm to estimate genetic variance in an animal threshold model using Bayesian inference Genetics Selection Evolution 2010, 42:29

    DEFF Research Database (Denmark)

    Ødegård, Jørgen; Meuwissen, Theo HE; Heringstad, Bjørg

    2010-01-01

    Background In the genetic analysis of binary traits with one observation per animal, animal threshold models frequently give biased heritability estimates. In some cases, this problem can be circumvented by fitting sire- or sire-dam models. However, these models are not appropriate in cases where...... records exist for the parents). Furthermore, the new algorithm showed much faster Markov chain mixing properties for genetic parameters (similar to the sire-dam model). Conclusions The new algorithm to estimate genetic parameters via Gibbs sampling solves the bias problems typically occurring in animal...... individual records exist on parents. Therefore, the aim of our study was to develop a new Gibbs sampling algorithm for a proper estimation of genetic (co)variance components within an animal threshold model framework. Methods In the proposed algorithm, individuals are classified as either "informative...

  10. Quantitative Structure-Use Relationship Model thresholds for Model Validation, Domain of Applicability, and Candidate Alternative Selection

    Data.gov (United States)

    U.S. Environmental Protection Agency — This file contains value of the model training set confusion matrix, domain of applicability evaluation based on training set to predicted chemicals structural...

  11. A two-dimensional analytical model for channel potential and threshold voltage of short channel dual material gate lightly doped drain MOSFET

    International Nuclear Information System (INIS)

    Tripathi Shweta

    2014-01-01

    An analytical model for the channel potential and the threshold voltage of the short channel dual-material-gate lightly doped drain (DMG-LDD) metal—oxide—semiconductor field-effect transistor (MOSFET) is presented using the parabolic approximation method. The proposed model takes into account the effects of the LDD region length, the LDD region doping, the lengths of the gate materials and their respective work functions, along with all the major geometrical parameters of the MOSFET. The impact of the LDD region length, the LDD region doping, and the channel length on the channel potential is studied in detail. Furthermore, the threshold voltage of the device is calculated using the minimum middle channel potential, and the result obtained is compared with the DMG MOSFET threshold voltage to show the improvement in the threshold voltage roll-off. It is shown that the DMG-LDD MOSFET structure alleviates the problem of short channel effects (SCEs) and the drain induced barrier lowering (DIBL) more efficiently. The proposed model is verified by comparing the theoretical results with the simulated data obtained by using the commercially available ATLAS™ 2D device simulator. (interdisciplinary physics and related areas of science and technology)

  12. A two-dimensional analytical model for channel potential and threshold voltage of short channel dual material gate lightly doped drain MOSFET

    Science.gov (United States)

    Shweta, Tripathi

    2014-11-01

    An analytical model for the channel potential and the threshold voltage of the short channel dual-material-gate lightly doped drain (DMG-LDD) metal—oxide—semiconductor field-effect transistor (MOSFET) is presented using the parabolic approximation method. The proposed model takes into account the effects of the LDD region length, the LDD region doping, the lengths of the gate materials and their respective work functions, along with all the major geometrical parameters of the MOSFET. The impact of the LDD region length, the LDD region doping, and the channel length on the channel potential is studied in detail. Furthermore, the threshold voltage of the device is calculated using the minimum middle channel potential, and the result obtained is compared with the DMG MOSFET threshold voltage to show the improvement in the threshold voltage roll-off. It is shown that the DMG-LDD MOSFET structure alleviates the problem of short channel effects (SCEs) and the drain induced barrier lowering (DIBL) more efficiently. The proposed model is verified by comparing the theoretical results with the simulated data obtained by using the commercially available ATLAS™ 2D device simulator.

  13. Bivariate threshold models for genetic evaluation of susceptibility to and ability to recover from mastitis in Danish Holstein cows.

    Science.gov (United States)

    Welderufael, B G; Janss, L L G; de Koning, D J; Sørensen, L P; Løvendahl, P; Fikse, W F

    2017-06-01

    Mastitis in dairy cows is an unavoidable problem and genetic variation in recovery from mastitis, in addition to susceptibility, is therefore of interest. Genetic parameters for susceptibility to and recovery from mastitis were estimated for Danish Holstein-Friesian cows using data from automatic milking systems equipped with online somatic cell count measuring units. The somatic cell count measurements were converted to elevated mastitis risk, a continuous variable [on a (0-1) scale] indicating the risk of mastitis. Risk values >0.6 were assumed to indicate that a cow had mastitis. For each cow and lactation, the sequence of health states (mastitic or healthy) was converted to a weekly transition: 0 if the cow stayed within the same state and 1 if the cow changed state. The result was 2 series of transitions: one for healthy to diseased (HD, to model mastitis susceptibility) and the other for diseased to healthy (DH, to model recovery ability). The 2 series of transitions were analyzed with bivariate threshold models, including several systematic effects and a function of time. The model included effects of herd, parity, herd-test-week, permanent environment (to account for the repetitive nature of transition records from a cow) plus two time-varying effects (lactation stage and time within episode). In early lactation, there was an increased risk of getting mastitis but the risk remained stable afterwards. Mean recovery rate was 45% per lactation. Heritabilities were 0.07 [posterior mean of standard deviations (PSD) = 0.03] for HD and 0.08 (PSD = 0.03) for DH. The genetic correlation between HD and DH has a posterior mean of -0.83 (PSD = 0.13). Although susceptibility and recovery from mastitis are strongly negatively correlated, recovery can be considered as a new trait for selection. The Authors. Published by the Federation of Animal Science Societies and Elsevier Inc. on behalf of the American Dairy Science Association®. This is an open access article under

  14. Optimizing Systems of Threshold Detection Sensors

    National Research Council Canada - National Science Library

    Banschbach, David C

    2008-01-01

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

  15. The threshold vs LNT showdown: Dose rate findings exposed flaws in the LNT model part 2. How a mistake led BEIR I to adopt LNT

    International Nuclear Information System (INIS)

    Calabrese, Edward J.

    2017-01-01

    This paper reveals that nearly 25 years after the used Russell's dose-rate data to support the adoption of the linear-no-threshold (LNT) dose response model for genetic and cancer risk assessment, Russell acknowledged a significant under-reporting of the mutation rate of the historical control group. This error, which was unknown to BEIR I, had profound implications, leading it to incorrectly adopt the LNT model, which was a decision that profoundly changed the course of risk assessment for radiation and chemicals to the present. -- Highlights: • The BEAR I Genetics Panel made an error in denying dose rate for mutation. • The BEIR I Genetics Subcommittee attempted to correct this dose rate error. • The control group used for risk assessment by BEIR I is now known to be in error. • Correcting this error contradicts the LNT, supporting a threshold model.

  16. The threshold vs LNT showdown: Dose rate findings exposed flaws in the LNT model part 2. How a mistake led BEIR I to adopt LNT

    Energy Technology Data Exchange (ETDEWEB)

    Calabrese, Edward J., E-mail: edwardc@schoolph.umass.edu [Department of Environmental Health Sciences, School of Public Health and Health Sciences, Morrill I, N344, University of Massachusetts, Amherst, MA 01003 (United States)

    2017-04-15

    This paper reveals that nearly 25 years after the used Russell's dose-rate data to support the adoption of the linear-no-threshold (LNT) dose response model for genetic and cancer risk assessment, Russell acknowledged a significant under-reporting of the mutation rate of the historical control group. This error, which was unknown to BEIR I, had profound implications, leading it to incorrectly adopt the LNT model, which was a decision that profoundly changed the course of risk assessment for radiation and chemicals to the present. -- Highlights: • The BEAR I Genetics Panel made an error in denying dose rate for mutation. • The BEIR I Genetics Subcommittee attempted to correct this dose rate error. • The control group used for risk assessment by BEIR I is now known to be in error. • Correcting this error contradicts the LNT, supporting a threshold model.

  17. The asymmetric reactions of mean and volatility of stock returns to domestic and international information based on a four-regime double-threshold GARCH model

    Science.gov (United States)

    Chen, Cathy W. S.; Yang, Ming Jing; Gerlach, Richard; Jim Lo, H.

    2006-07-01

    In this paper, we investigate the asymmetric reactions of mean and volatility of stock returns in five major markets to their own local news and the US information via linear and nonlinear models. We introduce a four-regime Double-Threshold GARCH (DTGARCH) model, which allows asymmetry in both the conditional mean and variance equations simultaneously by employing two threshold variables, to analyze the stock markets’ reactions to different types of information (good/bad news) generated from the domestic markets and the US stock market. By applying the four-regime DTGARCH model, this study finds that the interaction between the information of domestic and US stock markets leads to the asymmetric reactions of stock returns and their variability. In addition, this research also finds that the positive autocorrelation reported in the previous studies of financial markets may in fact be mis-specified, and actually due to the local market's positive response to the US stock market.

  18. Pathophysiology and multifactorial etiology of acquired vasospastic disease (Raynaud syndrome) in vibration-exposed workers.

    Science.gov (United States)

    Gemne, G

    1982-12-01

    The article reviews available pathophysiological evidence for a multifactorial etiology of the Raynaud type of peripheral circulation disorder in persons exposed to vibration from handheld tools and discusses the consequences this viewpoint may have for diagnostics, preventive work, and research.

  19. Using Generalized Additive Modeling to Empirically Identify Thresholds within the ITERS in Relation to Toddlers' Cognitive Development

    Science.gov (United States)

    Setodji, Claude Messan; Le, Vi-Nhuan; Schaack, Diana

    2013-01-01

    Research linking high-quality child care programs and children's cognitive development has contributed to the growing popularity of child care quality benchmarking efforts such as quality rating and improvement systems (QRIS). Consequently, there has been an increased interest in and a need for approaches to identifying thresholds, or cutpoints,…

  20. Influence of regression model and incremental test protocol on the relationship between lactate threshold using the maximal-deviation method and performance in female runners.

    Science.gov (United States)

    Machado, Fabiana Andrade; Nakamura, Fábio Yuzo; Moraes, Solange Marta Franzói De

    2012-01-01

    This study examined the influence of the regression model and initial intensity of an incremental test on the relationship between the lactate threshold estimated by the maximal-deviation method and the endurance performance. Sixteen non-competitive, recreational female runners performed a discontinuous incremental treadmill test. The initial speed was set at 7 km · h⁻¹, and increased every 3 min by 1 km · h⁻¹ with a 30-s rest between the stages used for earlobe capillary blood sample collection. Lactate-speed data were fitted by an exponential-plus-constant and a third-order polynomial equation. The lactate threshold was determined for both regression equations, using all the coordinates, excluding the first and excluding the first and second initial points. Mean speed of a 10-km road race was the performance index (3.04 ± 0.22 m · s⁻¹). The exponentially-derived lactate threshold had a higher correlation (0.98 ≤ r ≤ 0.99) and smaller standard error of estimate (SEE) (0.04 ≤ SEE ≤ 0.05 m · s⁻¹) with performance than the polynomially-derived equivalent (0.83 ≤ r ≤ 0.89; 0.10 ≤ SEE ≤ 0.13 m · s⁻¹). The exponential lactate threshold was greater than the polynomial equivalent (P performance index that is independent of the initial intensity of the incremental test and better than the polynomial equivalent.

  1. Implications of lower risk thresholds for statin treatment in primary prevention: analysis of CPRD and simulation modelling of annual cholesterol monitoring.

    Science.gov (United States)

    McFadden, Emily; Stevens, Richard; Glasziou, Paul; Perera, Rafael

    2015-01-01

    To estimate numbers affected by a recent change in UK guidelines for statin use in primary prevention of cardiovascular disease. We modelled cholesterol ratio over time using a sample of 45,151 men (≥40years) and 36,168 women (≥55years) in 2006, without statin treatment or previous cardiovascular disease, from the Clinical Practice Research Datalink. Using simulation methods, we estimated numbers indicated for new statin treatment, if cholesterol was measured annually and used in the QRISK2 CVD risk calculator, using the previous 20% and newly recommended 10% thresholds. We estimate that 58% of men and 55% of women would be indicated for treatment by five years and 71% of men and 73% of women by ten years using the 20% threshold. Using the proposed threshold of 10%, 84% of men and 90% of women would be indicated for treatment by 5years and 92% of men and 98% of women by ten years. The proposed change of risk threshold from 20% to 10% would result in the substantial majority of those recommended for cholesterol testing being indicated for statin treatment. Implications depend on the value of statins in those at low to medium risk, and whether there are harms. Copyright © 2014. Published by Elsevier Inc.

  2. Evaluation of the most suitable threshold value for modelling snow glacier melt through T- index approach: the case study of Forni Glacier (Italian Alps)

    Science.gov (United States)

    Senese, Antonella; Maugeri, Maurizio; Vuillermoz, Elisa; Smiraglia, Claudio; Diolaiuti, Guglielmina

    2014-05-01

    Glacier melt occurs whenever the surface temperature is null (273.15 K) and the net energy budget is positive. These conditions can be assessed by analyzing meteorological and energy data acquired by a supraglacial Automatic Weather Station (AWS). In the case this latter is not present at the glacier surface the assessment of actual melting conditions and the evaluation of melt amount is difficult and degree-day (also named T-index) models are applied. These approaches require the choice of a correct temperature threshold. In fact, melt does not necessarily occur at daily air temperatures higher than 273.15 K, since it is determined by the energy budget which in turn is only indirectly affected by air temperature. This is the case of the late spring period when ablation processes start at the glacier surface thus progressively reducing snow thickness. In this study, to detect the most indicative air temperature threshold witnessing melt conditions in the April-June period, we analyzed air temperature data recorded from 2006 to 2012 by a supraglacial AWS (at 2631 m a.s.l.) on the ablation tongue of the Forni Glacier (Italy), and by a weather station located nearby the studied glacier (at Bormio, 1225 m a.s.l.). Moreover we evaluated the glacier energy budget (which gives the actual melt, Senese et al., 2012) and the snow water equivalent values during this time-frame. Then the ablation amount was estimated both from the surface energy balance (MEB from supraglacial AWS data) and from degree-day method (MT-INDEX, in this latter case applying the mean tropospheric lapse rate to temperature data acquired at Bormio changing the air temperature threshold) and the results were compared. We found that the mean tropospheric lapse rate permits a good and reliable reconstruction of daily glacier air temperature conditions and the major uncertainty in the computation of snow melt from degree-day models is driven by the choice of an appropriate air temperature threshold. Then

  3. HERITABILITY AND BREEDING VALUE OF SHEEP FERTILITY ESTIMATED BY MEANS OF THE GIBBS SAMPLING METHOD USING THE LINEAR AND THRESHOLD MODELS

    Directory of Open Access Journals (Sweden)

    DARIUSZ Piwczynski

    2013-03-01

    Full Text Available The research was carried out on 4,030 Polish Merino ewes born in the years 1991- 2001, kept in 15 flocks from the Pomorze and Kujawy region. Fertility of ewes in subsequent reproduction seasons was analysed with the use of multiple logistic regression. The research showed that there is a statistical influence of the flock, year of birth, age of dam, flock year interaction of birth on the ewes fertility. In order to estimate the genetic parameters, the Gibbs sampling method was applied, using the univariate animal models, both linear as well as threshold. Estimates of fertility depending on the model equalled 0.067 to 0.104, whereas the estimates of repeatability equalled respectively: 0.076 and 0.139. The obtained genetic parameters were then used to estimate the breeding values of the animals in terms of controlled trait (Best Linear Unbiased Prediction method using linear and threshold models. The obtained animal breeding values rankings in respect of the same trait with the use of linear and threshold models were strongly correlated with each other (rs = 0.972. Negative genetic trends of fertility (0.01-0.08% per year were found.

  4. Heavy-ion fusion: Channel-coupling effects, the barrier penetration model, and the threshold anomaly for heavy-ion potentials

    International Nuclear Information System (INIS)

    Satchler, G.R.; Nagarajan, M.A.; Lilley, J.S.; Thompson, I.J.

    1987-01-01

    We study the formal structure of the influence of channel coupling on near- and sub-barrier fusion. The reduction to a one-channel description is studied, with emphasis on the channel-coupling effects being manifest primarily as an energy dependence (the ''threshold anomaly'') of the real nuclear potential. The relation to the barrier penetration model is examined critically. The results of large-scale coupled-channel calculations are used as ''data'' to illustrate the discussion. Particular emphasis is placed on the importance of reproducing correctly the partial-wave (or ''spin'') distributions. The simple barrier penetration model is found to be adequate to exhibit the strong enhancements due to channel couplings when the threshold anomaly is taken into account, although there may be important corrections due to the long-ranged peripheral absorption, especially from Coulomb excitation. copyright 1987 Academic Press, Inc

  5. Use of threshold-specific energy model for the prediction of effects of smoking and radon exposure on the risk of lung cancer

    International Nuclear Information System (INIS)

    Boehm, R.; Bulko, M.; Holy, K.; Sedlak, A.

    2014-01-01

    Lung cancer is the leading cause of cancer death in both men and women. Smoking causes 80-90 % of cases of lung cancer. In this study, an attempt was made to assess the impact of cigarette smoking on the risk of lung cancer by the so-called threshold-specific energy model. This model allows to analyse the biological effects of radon daughter products on the lung tissue, and is based on the assumption that the biological effect (i.e. cell inactivation) will manifest itself after the threshold-specific energy z0 deposited in the sensitive volume of the cell is exceeded. Cigarette smoking causes, among others, an increase in the synthesis of the surviving protein that protects cells from apoptosis and thereby reduces their radiosensitivity. Based on these facts, an attempt was made to estimate the shape of the curves describing the increase in the oncological effect of radiation as a function of daily cigarette consumption. (authors)

  6. CARA Risk Assessment Thresholds

    Science.gov (United States)

    Hejduk, M. D.

    2016-01-01

    Warning remediation threshold (Red threshold): Pc level at which warnings are issued, and active remediation considered and usually executed. Analysis threshold (Green to Yellow threshold): Pc level at which analysis of event is indicated, including seeking additional information if warranted. Post-remediation threshold: Pc level to which remediation maneuvers are sized in order to achieve event remediation and obviate any need for immediate follow-up maneuvers. Maneuver screening threshold: Pc compliance level for routine maneuver screenings (more demanding than regular Red threshold due to additional maneuver uncertainty).

  7. Efficient computational model for classification of protein localization images using Extended Threshold Adjacency Statistics and Support Vector Machines.

    Science.gov (United States)

    Tahir, Muhammad; Jan, Bismillah; Hayat, Maqsood; Shah, Shakir Ullah; Amin, Muhammad

    2018-04-01

    Discriminative and informative feature extraction is the core requirement for accurate and efficient classification of protein subcellular localization images so that drug development could be more effective. The objective of this paper is to propose a novel modification in the Threshold Adjacency Statistics technique and enhance its discriminative power. In this work, we utilized Threshold Adjacency Statistics from a novel perspective to enhance its discrimination power and efficiency. In this connection, we utilized seven threshold ranges to produce seven distinct feature spaces, which are then used to train seven SVMs. The final prediction is obtained through the majority voting scheme. The proposed ETAS-SubLoc system is tested on two benchmark datasets using 5-fold cross-validation technique. We observed that our proposed novel utilization of TAS technique has improved the discriminative power of the classifier. The ETAS-SubLoc system has achieved 99.2% accuracy, 99.3% sensitivity and 99.1% specificity for Endogenous dataset outperforming the classical Threshold Adjacency Statistics technique. Similarly, 91.8% accuracy, 96.3% sensitivity and 91.6% specificity values are achieved for Transfected dataset. Simulation results validated the effectiveness of ETAS-SubLoc that provides superior prediction performance compared to the existing technique. The proposed methodology aims at providing support to pharmaceutical industry as well as research community towards better drug designing and innovation in the fields of bioinformatics and computational biology. The implementation code for replicating the experiments presented in this paper is available at: https://drive.google.com/file/d/0B7IyGPObWbSqRTRMcXI2bG5CZWs/view?usp=sharing. Copyright © 2018 Elsevier B.V. All rights reserved.

  8. Efficiency using computer simulation of Reverse Threshold Model Theory on assessing a “One Laptop Per Child” computer versus desktop computer

    Directory of Open Access Journals (Sweden)

    Supat Faarungsang

    2017-04-01

    Full Text Available The Reverse Threshold Model Theory (RTMT model was introduced based on limiting factor concepts, but its efficiency compared to the Conventional Model (CM has not been published. This investigation assessed the efficiency of RTMT compared to CM using computer simulation on the “One Laptop Per Child” computer and a desktop computer. Based on probability values, it was found that RTMT was more efficient than CM among eight treatment combinations and an earlier study verified that RTMT gives complete elimination of random error. Furthermore, RTMT has several advantages over CM and is therefore proposed to be applied to most research data.

  9. Multifactorial risk assessment for survival of abutments of removable partial dentures based on practice-based longitudinal study.

    Science.gov (United States)

    Tada, Sayaka; Ikebe, Kazunori; Matsuda, Ken-Ichi; Maeda, Yoshinobu

    2013-12-01

    Predicting the tooth survival is such a great challenge for evidence-based dentistry. To prevent further tooth loss of partially edentulous patients, estimation of individualized risk and benefit for each residual tooth is important to the clinical decision-making. While there are several reports indicating a risk of losing the abutment teeth of RPDs, there are no existing reports exploring the cause of abutment loss by multifactorial analysis. The aim of this practice-based longitudinal study was to determine the prognostic factors affecting the survival period of RPD abutments using a multifactorial risk assessment. One hundred and forty-seven patients had been previously provided with a total of 236 new RPDs at the Osaka University Dental Hospital; the 856 abutments for these RPDs were analyzed. Survival of abutment teeth was estimated using the Kaplan-Meier method. Multivariate analysis was conducted by Cox's proportional hazard modelling. The 5-year survival rates were 86.6% for direct abutments and 93.1% for indirect abutments, compared with 95.8% survival in non-abutment teeth. The multivariate analysis showed that abutment survival was significantly associated with crown-root ratio (hazard ratio (HR): 3.13), root canal treatment (HR: 2.93), pocket depth (HR: 2.51), type of abutments (HR: 2.19) and occlusal support (HR: 1.90). From this practice-based longitudinal study, we concluded that RPD abutment teeth are more likely to be lost than other residual teeth. From the multifactorial risk factor assessment, several prognostic factors, such as occlusal support, crown-root ratio, root canal treatment, and pocket depth were suggested. These results could be used to estimate the individualized risk for the residual teeth, to predict the prognosis of RPD abutments and to facilitate an evidence-based clinical decision making. Copyright © 2013 Elsevier Ltd. All rights reserved.

  10. Coloring geographical threshold graphs

    Energy Technology Data Exchange (ETDEWEB)

    Bradonjic, Milan [Los Alamos National Laboratory; Percus, Allon [Los Alamos National Laboratory; Muller, Tobias [EINDHOVEN UNIV. OF TECH

    2008-01-01

    We propose a coloring algorithm for sparse random graphs generated by the geographical threshold graph (GTG) model, a generalization of random geometric graphs (RGG). In a GTG, nodes are distributed in a Euclidean space, and edges are assigned according to a threshold function involving the distance between nodes as well as randomly chosen node weights. The motivation for analyzing this model is that many real networks (e.g., wireless networks, the Internet, etc.) need to be studied by using a 'richer' stochastic model (which in this case includes both a distance between nodes and weights on the nodes). Here, we analyze the GTG coloring algorithm together with the graph's clique number, showing formally that in spite of the differences in structure between GTG and RGG, the asymptotic behavior of the chromatic number is identical: {chi}1n 1n n / 1n n (1 + {omicron}(1)). Finally, we consider the leading corrections to this expression, again using the coloring algorithm and clique number to provide bounds on the chromatic number. We show that the gap between the lower and upper bound is within C 1n n / (1n 1n n){sup 2}, and specify the constant C.

  11. Nasal inhalation of butorphanol in combination with ketamine quickly elevates the mechanical pain threshold in the model of chronic constriction injury to the sciatic nerve of rat.

    Science.gov (United States)

    Chen, Feng; Wang, LiQin; Chen, ShuJun; Li, ZhiGao; Chen, ZhouLin; Zhou, XinHua; Zhai, Dong

    2014-01-01

    The aim of the present study is to explore the impact of butorphanol in combination with ketamine via nasal inhalation (NI) on neuropathic pain induced by chronic constriction injury (CCI) to the sciatic nerve in a rat model. CCI rats (n = 12) were equally randomized to four groups based on the treatments received as follows: 100 μL of 0.9% normal saline via NI (NS/NI group); 100 μg of butorphanol plus 1 mg of ketamine via NI (B + K/NI group); 100 μg of butorphanol alone via NI (B/NI group); and 100 μg of butorphanol plus 1 mg of ketamine via subcutaneous injection (B + K/SC group). Mechanical pain threshold was measured at 10 min, 30 min, 2 h, 4 h, and 6 h after drug administration. The mechanical pain threshold in the B + K/NI group was improved significantly 4 h after drug administration as compared with that in the B/NI or B + K/SC group (P ketamine quickly elevates the mechanical pain threshold in a rat neuropathic pain model induced by CCI to the sciatic nerve. Copyright © 2014 Elsevier Inc. All rights reserved.

  12. Comparison of energy expenditure, body composition, metabolic disorders, and energy intake between obese children with a history of craniopharyngioma and children with multifactorial obesity.

    Science.gov (United States)

    Bomer, Ilanit; Saure, Carola; Caminiti, Carolina; Ramos, Javier Gonzales; Zuccaro, Graciela; Brea, Mercedes; Bravo, Mónica; Maza, Carmen

    2015-11-01

    Craniopharyngioma is a histologically benign brain malformation with a fundamental role in satiety modulation, causing obesity in up to 52% of patients. To evaluate cardiovascular risk factors, body composition, resting energy expenditure (REE), and energy intake in craniopharyngioma patients and to compare the data with those from children with multifactorial obesity. All obese children and adolescents who underwent craniopharyngioma resection and a control group of children with multifactorial obesity in follow-up between May 2012 and April 2013. Anthropometric measurements, bioelectrical impedance, indirect calorimetry, energy intake, homeostatic model assessment insulin resistance (HOMA-IR), and dyslipidemia were evaluated. Twenty-three patients with craniopharyngioma and 43 controls were included. Children with craniopharyngioma-related obesity had a lower fat-free mass percentage (62.4 vs. 67.5; p=0.01) and a higher fat mass percentage (37.5 vs. 32.5; p=0.01) compared to those with multifactorial obesity. A positive association was found between %REE and %fat-free mass in subjects with multifactorial obesity (68±1% in normal REE vs. 62.6±1% in low REE; p=0.04), but not in craniopharyngioma patients (62±2.7 in normal REE vs. 61.2±1.8% in low REE; p=0.8). No differences were found in metabolic involvement or energy intake. REE was lower in craniopharyngioma patients compared to children with multifactorial obesity regardless of the amount of fat-free mass, suggesting that other factors may be responsible for the lower REE.

  13. Threshold quantum cryptography

    International Nuclear Information System (INIS)

    Tokunaga, Yuuki; Okamoto, Tatsuaki; Imoto, Nobuyuki

    2005-01-01

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

  14. Evaluation of Bayesian estimation of a hidden continuous-time Markov chain model with application to threshold violation in water-quality indicators

    Science.gov (United States)

    Deviney, Frank A.; Rice, Karen; Brown, Donald E.

    2012-01-01

    Natural resource managers require information concerning  the frequency, duration, and long-term probability of occurrence of water-quality indicator (WQI) violations of defined thresholds. The timing of these threshold crossings often is hidden from the observer, who is restricted to relatively infrequent observations. Here, a model for the hidden process is linked with a model for the observations, and the parameters describing duration, return period, and long-term probability of occurrence are estimated using Bayesian methods. A simulation experiment is performed to evaluate the approach under scenarios based on the equivalent of a total monitoring period of 5-30 years and an observation frequency of 1-50 observations per year. Given constant threshold crossing rate, accuracy and precision of parameter estimates increased with longer total monitoring period and more-frequent observations. Given fixed monitoring period and observation frequency, accuracy and precision of parameter estimates increased with longer times between threshold crossings. For most cases where the long-term probability of being in violation is greater than 0.10, it was determined that at least 600 observations are needed to achieve precise estimates.  An application of the approach is presented using 22 years of quasi-weekly observations of acid-neutralizing capacity from Deep Run, a stream in Shenandoah National Park, Virginia. The time series also was sub-sampled to simulate monthly and semi-monthly sampling protocols. Estimates of the long-term probability of violation were unbiased despite sampling frequency; however, the expected duration and return period were over-estimated using the sub-sampled time series with respect to the full quasi-weekly time series.

  15. The threshold vs LNT showdown: Dose rate findings exposed flaws in the LNT model part 2. How a mistake led BEIR I to adopt LNT.

    Science.gov (United States)

    Calabrese, Edward J

    2017-04-01

    This paper reveals that nearly 25 years after the National Academy of Sciences (NAS), Biological Effects of Ionizing Radiation (BEIR) I Committee (1972) used Russell's dose-rate data to support the adoption of the linear-no-threshold (LNT) dose response model for genetic and cancer risk assessment, Russell acknowledged a significant under-reporting of the mutation rate of the historical control group. This error, which was unknown to BEIR I, had profound implications, leading it to incorrectly adopt the LNT model, which was a decision that profoundly changed the course of risk assessment for radiation and chemicals to the present. Copyright © 2016 Elsevier Inc. All rights reserved.

  16. An analytical threshold voltage model for a short-channel dual-metal-gate (DMG) recessed-source/drain (Re-S/D) SOI MOSFET

    Science.gov (United States)

    Saramekala, G. K.; Santra, Abirmoya; Dubey, Sarvesh; Jit, Satyabrata; Tiwari, Pramod Kumar

    2013-08-01

    In this paper, an analytical short-channel threshold voltage model is presented for a dual-metal-gate (DMG) fully depleted recessed source/drain (Re-S/D) SOI MOSFET. For the first time, the advantages of recessed source/drain (Re-S/D) and of dual-metal-gate structure are incorporated simultaneously in a fully depleted SOI MOSFET. The analytical surface potential model at Si-channel/SiO2 interface and Si-channel/buried-oxide (BOX) interface have been developed by solving the 2-D Poisson’s equation in the channel region with appropriate boundary conditions assuming parabolic potential profile in the transverse direction of the channel. Thereupon, a threshold voltage model is derived from the minimum surface potential in the channel. The developed model is analyzed extensively for a variety of device parameters like the oxide and silicon channel thicknesses, thickness of source/drain extension in the BOX, control and screen gate length ratio. The validity of the present 2D analytical model is verified with ATLAS™, a 2D device simulator from SILVACO Inc.

  17. Years of life gained by multifactorial intervention in patients with type 2 diabetes mellitus and microalbuminuria

    DEFF Research Database (Denmark)

    Gæde, Peter; Oellgaard, Jens; Carstensen, Bendix

    2016-01-01

    Aims/hypothesis: The aim of this work was to study the potential long-term impact of a 7.8 years intensified, multifactorial intervention in patients with type 2 diabetes mellitus and microalbuminuria in terms of gained years of life and years free from incident cardiovascular disease. Methods...... for all microvascular complications was decreased in the intensive-therapy group in the range 0.52 to 0.67, except for peripheral neuropathy (HR 1.12). Conclusions/interpretation: At 21.2 years of follow-up of 7.8 years of intensified, multifactorial, target-driven treatment of type 2 diabetes......: The original intervention (mean treatment duration 7.8 years) involved 160 patients with type 2 diabetes and microalbuminuria who were randomly assigned (using sealed envelopes) to receive either conventional therapy or intensified, multifactorial treatment including both behavioural and pharmacological...

  18. HMM-ModE – Improved classification using profile hidden Markov models by optimising the discrimination threshold and modifying emission probabilities with negative training sequences

    Directory of Open Access Journals (Sweden)

    Nandi Soumyadeep

    2007-03-01

    Full Text Available Abstract Background Profile Hidden Markov Models (HMM are statistical representations of protein families derived from patterns of sequence conservation in multiple alignments and have been used in identifying remote homologues with considerable success. These conservation patterns arise from fold specific signals, shared across multiple families, and function specific signals unique to the families. The availability of sequences pre-classified according to their function permits the use of negative training sequences to improve the specificity of the HMM, both by optimizing the threshold cutoff and by modifying emission probabilities to minimize the influence of fold-specific signals. A protocol to generate family specific HMMs is described that first constructs a profile HMM from an alignment of the family's sequences and then uses this model to identify sequences belonging to other classes that score above the default threshold (false positives. Ten-fold cross validation is used to optimise the discrimination threshold score for the model. The advent of fast multiple alignment methods enables the use of the profile alignments to align the true and false positive sequences, and the resulting alignments are used to modify the emission probabilities in the original model. Results The protocol, called HMM-ModE, was validated on a set of sequences belonging to six sub-families of the AGC family of kinases. These sequences have an average sequence similarity of 63% among the group though each sub-group has a different substrate specificity. The optimisation of discrimination threshold, by using negative sequences scored against the model improves specificity in test cases from an average of 21% to 98%. Further discrimination by the HMM after modifying model probabilities using negative training sequences is provided in a few cases, the average specificity rising to 99%. Similar improvements were obtained with a sample of G-Protein coupled receptors

  19. Minimum Transendothelial Electrical Resistance Thresholds for the Study of Small and Large Molecule Drug Transport in a Human in Vitro Blood-Brain Barrier Model.

    Science.gov (United States)

    Mantle, Jennifer L; Min, Lie; Lee, Kelvin H

    2016-12-05

    A human cell-based in vitro model that can accurately predict drug penetration into the brain as well as metrics to assess these in vitro models are valuable for the development of new therapeutics. Here, human induced pluripotent stem cells (hPSCs) are differentiated into a polarized monolayer that express blood-brain barrier (BBB)-specific proteins and have transendothelial electrical resistance (TEER) values greater than 2500 Ω·cm 2 . By assessing the permeabilities of several known drugs, a benchmarking system to evaluate brain permeability of drugs was established. Furthermore, relationships between TEER and permeability to both small and large molecules were established, demonstrating that different minimum TEER thresholds must be achieved to study the brain transport of these two classes of drugs. This work demonstrates that this hPSC-derived BBB model exhibits an in vivo-like phenotype, and the benchmarks established here are useful for assessing functionality of other in vitro BBB models.

  20. Multifactorial Determinants of the Neurocognitive Effects of Electroconvulsive Therapy

    Science.gov (United States)

    McClintock, Shawn M.; Choi, Jimmy; Deng, Zhi-De; Appelbaum, Lawrence G.; Krystal, Andrew D.; Lisanby, Sarah H.

    2014-01-01

    For many patients with neuropsychiatric illnesses, standard psychiatric treatments with mono or combination pharmacotherapy, psychotherapy, and transcranial magnetic stimulation are ineffective. For these patients with treatment resistant neuropsychiatric illnesses, a main therapeutic option is electroconvulsive therapy (ECT). Decades of research have found ECT to be highly effective; however, it can also result in adverse neurocognitive effects. Specifically, ECT results in disorientation after each session, anterograde amnesia for recently learned information, and retrograde amnesia for previously learned information. Unfortunately, the neurocognitive effects and underlying mechanisms of action of ECT remain poorly understood. The purpose of this paper is to synthesize the multiple moderating and mediating factors that are thought to underlie the neurocognitive effects of ECT into a coherent model. Such factors include demographic and neuropsychological characteristics, neuropsychiatric symptoms, ECT technical parameters, and ECT associated neurophysiological changes. Future research is warranted to evaluate and test this model, so that these findings may support the development of more refined clinical seizure therapy delivery approaches and efficacious cognitive remediation strategies to improve the utility of this important and widely used intervention tool for neuropsychiatric diseases. PMID:24820942

  1. Workplace Bullying among Managers: A Multifactorial Perspective and Understanding

    Science.gov (United States)

    Ariza-Montes, J. Antonio; Muniz R., Noel M.; Leal-Rodríguez, Antonio L.; Leal-Millán, Antonio G.

    2014-01-01

    The aim of this paper is to study certain factors that may be determinant in the emergence of workplace bullying among managers—employees with a recognized and privileged position to exercise power—adopting the individual perspective of the subject, the bullied manager. Individual, organizational, and contextual factors integrate the developed global model, and the methodology utilized to accomplish our research objectives is based on the binary logistic regression model. A sample population of 661 managers was obtained from the micro data file of the 5th European Working Conditions Survey-2010 (European Foundation for the Improvement of Living and Working Conditions) and utilized to conduct the present research. The results indicate that the chance for a manager to refer to him/herself as bullied increases among women that hold managerial positions and live with children under 15 at home, and among subjects that work at night, on a shift system, suffering from work stress, enjoying little satisfaction from their working conditions, and not perceiving opportunities for promotions in their organizations. The present work summarizes an array of outcomes and proposes, within the usual course of events, that workplace bullying could be reduced if job demands were limited and job resources were increased. The implications of these findings could assist directors/general directors in facilitating, to some extent, good social relationships among managers. PMID:24599041

  2. Workplace bullying among managers: a multifactorial perspective and understanding.

    Science.gov (United States)

    Ariza-Montes, J Antonio; Muniz R, Noel M; Leal-Rodríguez, Antonio L; Leal-Millán, Antonio G

    2014-03-04

    The aim of this paper is to study certain factors that may be determinant in the emergence of workplace bullying among managers-employees with a recognized and privileged position to exercise power-adopting the individual perspective of the subject, the bullied manager. Individual, organizational, and contextual factors integrate the developed global model, and the methodology utilized to accomplish our research objectives is based on the binary logistic regression model. A sample population of 661 managers was obtained from the micro data file of the 5th European Working Conditions Survey-2010 (European Foundation for the Improvement of Living and Working Conditions) and utilized to conduct the present research. The results indicate that the chance for a manager to refer to him/herself as bullied increases among women that hold managerial positions and live with children under 15 at home, and among subjects that work at night, on a shift system, suffering from work stress, enjoying little satisfaction from their working conditions, and not perceiving opportunities for promotions in their organizations. The present work summarizes an array of outcomes and proposes, within the usual course of events, that workplace bullying could be reduced if job demands were limited and job resources were increased. The implications of these findings could assist directors/general directors in facilitating, to some extent, good social relationships among managers.

  3. Workplace Bullying among Managers: A Multifactorial Perspective and Understanding

    Directory of Open Access Journals (Sweden)

    J. Antonio Ariza-Montes

    2014-03-01

    Full Text Available The aim of this paper is to study certain factors that may be determinant in the emergence of workplace bullying among managers—employees with a recognized and privileged position to exercise power—adopting the individual perspective of the subject, the bullied manager. Individual, organizational, and contextual factors integrate the developed global model, and the methodology utilized to accomplish our research objectives is based on the binary logistic regression model. A sample population of 661 managers was obtained from the micro data file of the 5th European Working Conditions Survey-2010 (European Foundation for the Improvement of Living and Working Conditions and utilized to conduct the present research. The results indicate that the chance for a manager to refer to him/herself as bullied increases among women that hold managerial positions and live with children under 15 at home, and among subjects that work at night, on a shift system, suffering from work stress, enjoying little satisfaction from their working conditions, and not perceiving opportunities for promotions in their organizations. The present work summarizes an array of outcomes and proposes, within the usual course of events, that workplace bullying could be reduced if job demands were limited and job resources were increased. The implications of these findings could assist directors/general directors in facilitating, to some extent, good social relationships among managers.

  4. Multifactorial intervention in individuals with type 2 diabetes and microalbuminuria

    DEFF Research Database (Denmark)

    Crasto, W.; Jarvis, J.; Khunti, K.

    2011-01-01

    Aims: To determine whether tighter cardiovascular risk factor control with structured education in individuals with type 2 diabetes (T2DM) and microalbuminuria benefits cardiovascular risk factors. Methods: Participants from a multiethnic population, recruited from primary care and specialist...... risk factor targets, modelled cardiovascular risk scores. Results: Mean (SD) age and diabetes duration of participants were 61.5 (10.5) and 11.5 (9.3) years, respectively. At 18. months, intensive intervention showed significant improvements in HbA1c (7.1(1.0) vs. 7.8(1.4)%, p... (129(16) vs. 139(17) mmHg, p2 vs. 29.0%; p= 0.001 and 0 vs. 6.3%; p= 0.07, respectively. More intensive participants achieved ≥3 risk factor...

  5. Intensive multifactorial treatment modifies the effect of family history of diabetes on glycaemic control in people with Type 2 diabetes

    DEFF Research Database (Denmark)

    Eliraqi, G M; Vistisen, D; Lauritzen, T

    2015-01-01

    Aim To investigate whether intensive multifactorial treatment can reverse the predisposed adverse phenotype of people with Type 2 diabetes who have a family history of diabetes. Methods Data from the randomized controlled trial ADDITION-Denmark were used. A total of 1441 newly diagnosed patients...... pressure, lipids and HbA1c) after 5 years of follow-up in participants with and without a family history of diabetes. An interaction term between family history of diabetes and treatment group was included in the models to test for a modifying effect of the intervention. All analyses were adjusted for age...... with diabetes (598 with family history of diabetes) were randomized to intensive treatment or routine care. Family history of diabetes was defined as having one parent and/or sibling with diabetes. Linear mixed-effects models were used to assess the changes in risk factors (BMI, waist circumference, blood...

  6. Computer Simulation of Noise Effects of the Neighborhood of Stimulus Threshold for a Mathematical Model of Homeostatic Regulation of Sleep-Wake Cycles

    Directory of Open Access Journals (Sweden)

    Wuyin Jin

    2017-01-01

    Full Text Available The noise effects on a homeostatic regulation of sleep-wake cycles’ neuronal mathematical model determined by the hypocretin/orexin and the local glutamate interneurons spatiotemporal behaviors are studied within the neighborhood of stimulus threshold in this work; the neuronal noise added to the stimulus, the conductance, and the activation variable of the modulation function are investigated, respectively, based on a circadian input skewed in sine function. The computer simulation results suggested that the increased amplitude of external current input will lead to the fact that awakening time is advanced but the sleepy time remains the same; for the bigger conductance and modulation noise, the regulatory mechanism of the model sometimes will be collapsed and the coupled two neurons of the model show very irregular activities; the falling asleep or wake transform appears at nondeterminate time.

  7. Model Predictions and Measured Skin Damage Thresholds for 1.54 Micrometers Laser Pulses in Porcine Skin

    National Research Council Canada - National Science Library

    Roach, William P; Cain, Clarence; Schuster, Kurt; Stockton, Kevin; Stolarski, David S; Galloway, Robert; Rockwell, Benjamin

    2004-01-01

    A new source-term thermal model was used to determine the skin temperature rise using porcine skin parameters for various wavelengths, pulse durations, and laser spot sizes and is compared to the Takata thermal model...

  8. The effect of social isolation, gender and familiarity with the experimental procedure on tests of porcine nociceptive thresholds

    DEFF Research Database (Denmark)

    di Giminiani, Pierpaolo; Stausholm, Julie S.; Viitasaari, Eliina

    2015-01-01

    Objective To investigate the effects of habituation and isolation on mechanical nociceptive thresholds in pigs at the pelvic limbs and at the tail. Study design Prospective randomized multifactorial study. Animals Thirty-two healthy castrated male (experiment 1), and 12 castrated male and 12 female...

  9. Carrying capacity models should not use fixed prey density thresholds : a plea for using more tools of behavioural ecology

    NARCIS (Netherlands)

    van Gils, JA; Edelaar, P; Escudero, G; Piersma, T

    Earlier studies have developed models of carrying capacity to predict the number of animals a certain area can support. These models assume that resources are not renewed after consumption ('standing stock' models), and that the initial number of prey and the rate of prey consumption determine the

  10. The calculation of human toxicity thresholds of 2,3,7,8-TCDD; A Physiologically Based Pharmacokinetic modeling approach

    NARCIS (Netherlands)

    Zeilmaker MJ; van Eijkeren JCH; LBO

    1998-01-01

    Dit rapport beschrijft de toepassing van een 'Physiologically Based PharmacoKinetic' model (PBPK model) bij het berekenen van de verwachte 'No Adverse Effect Level' van 2,3,7,8-TetraChloroDibenzo-p-Dioxine (TCDD) bij de mens. Het model houdt rekening met variabiliteit en

  11. A threshold for dissipative fission

    International Nuclear Information System (INIS)

    Thoennessen, M.; Bertsch, G.F.

    1993-01-01

    The empirical domain of validity of statistical theory is examined as applied to fission data on pre-fission data on pre-fission neutron, charged particle, and γ-ray multiplicities. Systematics are found of the threshold excitation energy for the appearance of nonstatistical fission. From the data on systems with not too high fissility, the relevant phenomenological parameter is the ratio of the threshold temperature T thresh to the (temperature-dependent) fission barrier height E Bar (T). The statistical model reproduces the data for T thresh /E Bar (T) thresh /E Bar (T) independent of mass and fissility of the systems

  12. Threshold Signature Schemes Application

    Directory of Open Access Journals (Sweden)

    Anastasiya Victorovna Beresneva

    2015-10-01

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

  13. Particles near threshold

    International Nuclear Information System (INIS)

    Bhattacharya, T.; Willenbrock, S.

    1993-01-01

    We propose returning to the definition of the width of a particle in terms of the pole in the particle's propagator. Away from thresholds, this definition of width is equivalent to the standard perturbative definition, up to next-to-leading order; however, near a threshold, the two definitions differ significantly. The width as defined by the pole position provides more information in the threshold region than the standard perturbative definition and, in contrast with the perturbative definition, does not vanish when a two-particle s-wave threshold is approached from below

  14. The effects of a rise in cigarette price on cigarette consumption, tobacco taxation revenues, and of smoking-related deaths in 28 EU countries-- applying threshold regression modelling

    Directory of Open Access Journals (Sweden)

    Chun-Yuan Yeh

    2017-09-01

    Full Text Available Abstract Background European Union public healthcare expenditure on treating smoking and attributable diseases is estimated at over €25bn annually. The reduction of tobacco consumption has thus become one of the major social policies of the EU. This study investigates the effects of price hikes on cigarette consumption, tobacco tax revenues and smoking-caused deaths in 28 EU countries. Methods Employing panel data for the years 2005 to 2014 from Euromonitor International, the World Bank and the World Health Organization, we used income as a threshold variable and applied threshold regression modelling to estimate the elasticity of cigarette prices and to simulate the effect of price fluctuations. Results The results showed that there was an income threshold effect on cigarette prices in the 28 EU countries that had a gross national income (GNI per capita lower than US$5418, with a maximum cigarette price elasticity of −1.227. The results of the simulated analysis showed that a rise of 10% in cigarette price would significantly reduce cigarette consumption as well the total death toll caused by smoking in all the observed countries, but would be most effective in Bulgaria and Romania, followed by Latvia and Poland. Additionally, an increase in the number of MPOWER tobacco control policies at the highest level of achievment would help reduce cigarette consumption. Conclusions It is recommended that all EU countries levy higher tobacco taxes to increase cigarette prices, and thus in effect reduce cigarette consumption. The subsequent increase in tobacco tax revenues would be instrumental in covering expenditures related to tobacco prevention and control programs.

  15. The effects of a rise in cigarette price on cigarette consumption, tobacco taxation revenues, and of smoking-related deaths in 28 EU countries-- applying threshold regression modelling.

    Science.gov (United States)

    Yeh, Chun-Yuan; Schafferer, Christian; Lee, Jie-Min; Ho, Li-Ming; Hsieh, Chi-Jung

    2017-09-21

    European Union public healthcare expenditure on treating smoking and attributable diseases is estimated at over €25bn annually. The reduction of tobacco consumption has thus become one of the major social policies of the EU. This study investigates the effects of price hikes on cigarette consumption, tobacco tax revenues and smoking-caused deaths in 28 EU countries. Employing panel data for the years 2005 to 2014 from Euromonitor International, the World Bank and the World Health Organization, we used income as a threshold variable and applied threshold regression modelling to estimate the elasticity of cigarette prices and to simulate the effect of price fluctuations. The results showed that there was an income threshold effect on cigarette prices in the 28 EU countries that had a gross national income (GNI) per capita lower than US$5418, with a maximum cigarette price elasticity of -1.227. The results of the simulated analysis showed that a rise of 10% in cigarette price would significantly reduce cigarette consumption as well the total death toll caused by smoking in all the observed countries, but would be most effective in Bulgaria and Romania, followed by Latvia and Poland. Additionally, an increase in the number of MPOWER tobacco control policies at the highest level of achievment would help reduce cigarette consumption. It is recommended that all EU countries levy higher tobacco taxes to increase cigarette prices, and thus in effect reduce cigarette consumption. The subsequent increase in tobacco tax revenues would be instrumental in covering expenditures related to tobacco prevention and control programs.

  16. Application of the predicted heat strain model in development of localized, threshold-based heat stress management guidelines for the construction industry.

    Science.gov (United States)

    Rowlinson, Steve; Jia, Yunyan Andrea

    2014-04-01

    Existing heat stress risk management guidelines recommended by international standards are not practical for the construction industry which needs site supervision staff to make instant managerial decisions to mitigate heat risks. The ability of the predicted heat strain (PHS) model [ISO 7933 (2004). Ergonomics of the thermal environment analytical determination and interpretation of heat stress using calculation of the predicted heat strain. Geneva: International Standard Organisation] to predict maximum allowable exposure time (D lim) has now enabled development of localized, action-triggering and threshold-based guidelines for implementation by lay frontline staff on construction sites. This article presents a protocol for development of two heat stress management tools by applying the PHS model to its full potential. One of the tools is developed to facilitate managerial decisions on an optimized work-rest regimen for paced work. The other tool is developed to enable workers' self-regulation during self-paced work.

  17. From individual to population level effects of toxicants in the tubicifid Branchiura sowerbyi using threshold effect models in a Bayesian framework.

    Science.gov (United States)

    Ducrot, Virginie; Billoir, Elise; Péry, Alexandre R R; Garric, Jeanne; Charles, Sandrine

    2010-05-01

    Effects of zinc were studied in the freshwater worm Branchiura sowerbyi using partial and full life-cycle tests. Only newborn and juveniles were sensitive to zinc, displaying effects on survival, growth, and age at first brood at environmentally relevant concentrations. Threshold effect models were proposed to assess toxic effects on individuals. They were fitted to life-cycle test data using Bayesian inference and adequately described life-history trait data in exposed organisms. The daily asymptotic growth rate of theoretical populations was then simulated with a matrix population model, based upon individual-level outputs. Population-level outputs were in accordance with existing literature for controls. Working in a Bayesian framework allowed incorporating parameter uncertainty in the simulation of the population-level response to zinc exposure, thus increasing the relevance of test results in the context of ecological risk assessment.

  18. A Vulnerability-Based, Bottom-up Assessment of Future Riverine Flood Risk Using a Modified Peaks-Over-Threshold Approach and a Physically Based Hydrologic Model

    Science.gov (United States)

    Knighton, James; Steinschneider, Scott; Walter, M. Todd

    2017-12-01

    There is a chronic disconnection among purely probabilistic flood frequency analysis of flood hazards, flood risks, and hydrological flood mechanisms, which hamper our ability to assess future flood impacts. We present a vulnerability-based approach to estimating riverine flood risk that accommodates a more direct linkage between decision-relevant metrics of risk and the dominant mechanisms that cause riverine flooding. We adapt the conventional peaks-over-threshold (POT) framework to be used with extreme precipitation from different climate processes and rainfall-runoff-based model output. We quantify the probability that at least one adverse hydrologic threshold, potentially defined by stakeholders, will be exceeded within the next N years. This approach allows us to consider flood risk as the summation of risk from separate atmospheric mechanisms, and supports a more direct mapping between hazards and societal outcomes. We perform this analysis within a bottom-up framework to consider the relevance and consequences of information, with varying levels of credibility, on changes to atmospheric patterns driving extreme precipitation events. We demonstrate our proposed approach using a case study for Fall Creek in Ithaca, NY, USA, where we estimate the risk of stakeholder-defined flood metrics from three dominant mechanisms: summer convection, tropical cyclones, and spring rain and snowmelt. Using downscaled climate projections, we determine how flood risk associated with a subset of mechanisms may change in the future, and the resultant shift to annual flood risk. The flood risk approach we propose can provide powerful new insights into future flood threats.

  19. The threshold vs LNT showdown: Dose rate findings exposed flaws in the LNT model part 1. The Russell-Muller debate

    Energy Technology Data Exchange (ETDEWEB)

    Calabrese, Edward J., E-mail: edwardc@schoolph.umass.edu

    2017-04-15

    This paper assesses the discovery of the dose-rate effect in radiation genetics and how it challenged fundamental tenets of the linear non-threshold (LNT) dose response model, including the assumptions that all mutational damage is cumulative and irreversible and that the dose-response is linear at low doses. Newly uncovered historical information also describes how a key 1964 report by the International Commission for Radiological Protection (ICRP) addressed the effects of dose rate in the assessment of genetic risk. This unique story involves assessments by two leading radiation geneticists, Hermann J. Muller and William L. Russell, who independently argued that the report's Genetic Summary Section on dose rate was incorrect while simultaneously offering vastly different views as to what the report's summary should have contained. This paper reveals occurrences of scientific disagreements, how conflicts were resolved, which view(s) prevailed and why. During this process the Nobel Laureate, Muller, provided incorrect information to the ICRP in what appears to have been an attempt to manipulate the decision-making process and to prevent the dose-rate concept from being adopted into risk assessment practices. - Highlights: • The discovery of radiation dose rate challenged the scientific basis of LNT. • Radiation dose rate occurred in males and females. • The dose rate concept supported a threshold dose-response for radiation.

  20. The threshold vs LNT showdown: Dose rate findings exposed flaws in the LNT model part 1. The Russell-Muller debate

    International Nuclear Information System (INIS)

    Calabrese, Edward J.

    2017-01-01

    This paper assesses the discovery of the dose-rate effect in radiation genetics and how it challenged fundamental tenets of the linear non-threshold (LNT) dose response model, including the assumptions that all mutational damage is cumulative and irreversible and that the dose-response is linear at low doses. Newly uncovered historical information also describes how a key 1964 report by the International Commission for Radiological Protection (ICRP) addressed the effects of dose rate in the assessment of genetic risk. This unique story involves assessments by two leading radiation geneticists, Hermann J. Muller and William L. Russell, who independently argued that the report's Genetic Summary Section on dose rate was incorrect while simultaneously offering vastly different views as to what the report's summary should have contained. This paper reveals occurrences of scientific disagreements, how conflicts were resolved, which view(s) prevailed and why. During this process the Nobel Laureate, Muller, provided incorrect information to the ICRP in what appears to have been an attempt to manipulate the decision-making process and to prevent the dose-rate concept from being adopted into risk assessment practices. - Highlights: • The discovery of radiation dose rate challenged the scientific basis of LNT. • Radiation dose rate occurred in males and females. • The dose rate concept supported a threshold dose-response for radiation.

  1. Semiparametric profile likelihood estimation for continuous outcomes with excess zeros in a random-threshold damage-resistance model.

    Science.gov (United States)

    Rice, John D; Tsodikov, Alex

    2017-05-30

    Continuous outcome data with a proportion of observations equal to zero (often referred to as semicontinuous data) arise frequently in biomedical studies. Typical approaches involve two-part models, with one part a logistic model for the probability of observing a zero and some parametric continuous distribution for modeling the positive part of the data. We propose a semiparametric model based on a biological system with competing damage manifestation and resistance processes. This allows us to derive a closed-form profile likelihood based on the retro-hazard function, leading to a flexible procedure for modeling continuous data with a point mass at zero. A simulation study is presented to examine the properties of the method in finite samples. We apply the method to a data set consisting of pulmonary capillary hemorrhage area in lab rats subjected to diagnostic ultrasound. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

  2. Threshold behavior in electron-atom scattering

    International Nuclear Information System (INIS)

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

    1996-01-01

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

  3. DOE approach to threshold quantities

    International Nuclear Information System (INIS)

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

    1985-01-01

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

  4. Threshold enhancement of diphoton resonances

    Directory of Open Access Journals (Sweden)

    Aoife Bharucha

    2016-10-01

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

  5. Hybrid Microfluidic Platform for Multifactorial Analysis Based on Electrical Impedance, Refractometry, Optical Absorption and Fluorescence

    Directory of Open Access Journals (Sweden)

    Fábio M. Pereira

    2016-10-01

    Full Text Available This paper describes the development of a novel microfluidic platform for multifactorial analysis integrating four label-free detection methods: electrical impedance, refractometry, optical absorption and fluorescence. We present the rationale for the design and the details of the microfabrication of this multifactorial hybrid microfluidic chip. The structure of the platform consists of a three-dimensionally patterned polydimethylsiloxane top part attached to a bottom SU-8 epoxy-based negative photoresist part, where microelectrodes and optical fibers are incorporated to enable impedance and optical analysis. As a proof of concept, the chip functions have been tested and explored, enabling a diversity of applications: (i impedance-based identification of the size of micro beads, as well as counting and distinguishing of erythrocytes by their volume or membrane properties; (ii simultaneous determination of the refractive index and optical absorption properties of solutions; and (iii fluorescence-based bead counting.

  6. MLQ (Chestionarul Multifactorial de Leadership). Date preliminare pentru România

    OpenAIRE

    Dragoş Iliescu; Rareş Mocanu; Felicia Beldean

    2008-01-01

    The Multifactorial Leadership Questionnaire (MLQ), in its latest version (5X), is a complex instrument, created in order to offer (1) a valid measurement of the transformational, transactional and passive components of leadership and also (2) as accurate a profile as possible for a person’s leadership potential and leadership-related behavior. The MLQ has been often used in laboratory and field researches, being an adequate, very useful tool for selection, transfer, promotion, development and...

  7. Development of a population-based threshold model of conidial germination for analysing the effects of physiological manipulation on the stress tolerance and infectivity of insect pathogenic fungi.

    Science.gov (United States)

    Andersen, M; Magan, N; Mead, A; Chandler, D

    2006-09-01

    Entomopathogenic fungi are being used as biocontrol agents of insect pests, but their efficacy can be poor in environments where water availability is reduced. In this study, the potential to improve biocontrol by physiologically manipulating fungal inoculum was investigated. Cultures of Beauveria bassiana, Lecanicillium muscarium, Lecanicillium longisporum, Metarhizium anisopliae and Paecilomyces fumosoroseus were manipulated by growing them under conditions of water stress, which produced conidia with increased concentrations of erythritol. The time-course of germination of conidia at different water activities (water activity, aw) was described using a generalized linear model, and in most cases reducing the water activity of the germination medium delayed the onset of germination without affecting the distribution of germination times. The germination of M. anisopliae, L. muscarium, L. longisporum and P. fumosoroseus was accelerated over a range of aw levels as a result of physiological manipulation. However, the relationship between the effect of physiological manipulation on germination and the osmolyte content of conidia varied according to fungal species. There was a linear relationship between germination rate, expressed as the reciprocal of germination time, and aw of the germination medium, but there was no significant effect of fungal species or physiological manipulation on the aw threshold for germination. In bioassays with M. anisopliae, physiologically manipulated conidia germinated more rapidly on the surface of an insect host, the melon cotton aphid Aphis gossypii, and fungal virulence was increased even when relative humidity was reduced after an initial high period. It is concluded that physiological manipulation may lead to improvements in biocontrol in the field, but choice of fungal species/isolate will be critical. In addition, the population-based threshold model used in this study, which considered germination in terms of physiological

  8. Winner's Curse Correction and Variable Thresholding Improve Performance of Polygenic Risk Modeling Based on Genome-Wide Association Study Summary-Level Data.

    Directory of Open Access Journals (Sweden)

    Jianxin Shi

    2016-12-01

    Full Text Available Recent heritability analyses have indicated that genome-wide association studies (GWAS have the potential to improve genetic risk prediction for complex diseases based on polygenic risk score (PRS, a simple modelling technique that can be implemented using summary-level data from the discovery samples. We herein propose modifications to improve the performance of PRS. We introduce threshold-dependent winner's-curse adjustments for marginal association coefficients that are used to weight the single-nucleotide polymorphisms (SNPs in PRS. Further, as a way to incorporate external functional/annotation knowledge that could identify subsets of SNPs highly enriched for associations, we propose variable thresholds for SNPs selection. We applied our methods to GWAS summary-level data of 14 complex diseases. Across all diseases, a simple winner's curse correction uniformly led to enhancement of performance of the models, whereas incorporation of functional SNPs was beneficial only for selected diseases. Compared to the standard PRS algorithm, the proposed methods in combination led to notable gain in efficiency (25-50% increase in the prediction R2 for 5 of 14 diseases. As an example, for GWAS of type 2 diabetes, winner's curse correction improved prediction R2 from 2.29% based on the standard PRS to 3.10% (P = 0.0017 and incorporating functional annotation data further improved R2 to 3.53% (P = 2×10-5. Our simulation studies illustrate why differential treatment of certain categories of functional SNPs, even when shown to be highly enriched for GWAS-heritability, does not lead to proportionate improvement in genetic risk-prediction because of non-uniform linkage disequilibrium structure.

  9. Thresholds in chemical respiratory sensitisation.

    Science.gov (United States)

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

    2015-07-03

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

  10. Thresholds in radiobiology

    International Nuclear Information System (INIS)

    Katz, R.; Hofmann, W.

    1982-01-01

    Interpretations of biological radiation effects frequently use the word 'threshold'. The meaning of this word is explored together with its relationship to the fundamental character of radiation effects and to the question of perception. It is emphasised that although the existence of either a dose or an LET threshold can never be settled by experimental radiobiological investigations, it may be argued on fundamental statistical grounds that for all statistical processes, and especially where the number of observed events is small, the concept of a threshold is logically invalid. (U.K.)

  11. Computational modeling of distinct neocortical oscillations driven by cell-type selective optogenetic drive: Separable resonant circuits controlled by low-threshold spiking and fast-spiking interneurons

    Directory of Open Access Journals (Sweden)

    Dorea Vierling-Claassen

    2010-11-01

    Full Text Available Selective optogenetic drive of fast spiking interneurons (FS leads to enhanced local field potential (LFP power across the traditional gamma frequency band (20-80Hz; Cardin et al., 2009. In contrast, drive to regular-spiking pyramidal cells (RS enhances power at lower frequencies, with a peak at 8 Hz. The first result is consistent with previous computational studies emphasizing the role of FS and the time constant of GABAA synaptic inhibition in gamma rhythmicity. However, the same theoretical models do not typically predict low-frequency LFP enhancement with RS drive. To develop hypotheses as to how the same network can support these contrasting behaviors, we constructed a biophysically principled network model of primary somatosensory neocortex containing FS, RS and low-threshold-spiking (LTS interneurons. Cells were modeled with detailed cell anatomy and physiology, multiple dendritic compartments, and included active somatic and dendritic ionic currents. Consistent with prior studies, the model demonstrated gamma resonance during FS drive, dependent on the time-constant of GABAA inhibition induced by synchronous FS activity. Lower frequency enhancement during RS drive was replicated only on inclusion of an inhibitory LTS population, whose activation was critically dependent on RS synchrony and evoked longer-lasting inhibition. Our results predict that differential recruitment of FS and LTS inhibitory populations is essential to the observed cortical dynamics and may provide a means for amplifying the natural expression of distinct oscillations in normal cortical processing.

  12. Multiscalar production amplitudes beyond threshold

    CERN Document Server

    Argyres, E N; Kleiss, R H

    1993-01-01

    We present exact tree-order amplitudes for $H^* \\to n~H$, for final states containing one or two particles with non-zero three-momentum, for various interaction potentials. We show that there are potentials leading to tree amplitudes that satisfy unitarity, not only at threshold but also in the above kinematical configurations and probably beyond. As a by-product, we also calculate $2\\to n$ tree amplitudes at threshold and show that for the unbroken $\\phi^4$ theory they vanish for $n>4~$, for the Standard Model Higgs they vanish for $n\\ge 3~$ and for a model potential, respecting tree-order unitarity, for $n$ even and $n>4~$. Finally, we calculate the imaginary part of the one-loop $1\\to n$ amplitude in both symmetric and spontaneously broken $\\phi^4$ theory.

  13. A Threshold Continuum for Aeolian Sand Transport

    Science.gov (United States)

    Swann, C.; Ewing, R. C.; Sherman, D. J.

    2015-12-01

    The threshold of motion for aeolian sand transport marks the initial entrainment of sand particles by the force of the wind. This is typically defined and modeled as a singular wind speed for a given grain size and is based on field and laboratory experimental data. However, the definition of threshold varies significantly between these empirical models, largely because the definition is based on visual-observations of initial grain movement. For example, in his seminal experiments, Bagnold defined threshold of motion when he observed that 100% of the bed was in motion. Others have used 50% and lesser values. Differences in threshold models, in turn, result is large errors in predicting the fluxes associated with sand and dust transport. Here we use a wind tunnel and novel sediment trap to capture the fractions of sand in creep, reptation and saltation at Earth and Mars pressures and show that the threshold of motion for aeolian sand transport is best defined as a continuum in which grains progress through stages defined by the proportion of grains in creep and saltation. We propose the use of scale dependent thresholds modeled by distinct probability distribution functions that differentiate the threshold based on micro to macro scale applications. For example, a geologic timescale application corresponds to a threshold when 100% of the bed in motion whereas a sub-second application corresponds to a threshold when a single particle is set in motion. We provide quantitative measurements (number and mode of particle movement) corresponding to visual observations, percent of bed in motion and degrees of transport intermittency for Earth and Mars. Understanding transport as a continuum provides a basis for revaluating sand transport thresholds on Earth, Mars and Titan.

  14. Towards thresholds of disaster management performance under demographic change: exploring functional relationships using agent-based modeling

    Directory of Open Access Journals (Sweden)

    G. Dressler

    2016-10-01

    Full Text Available Effective disaster management is a core feature for the protection of communities against natural disasters such as floods. Disaster management organizations (DMOs are expected to contribute to ensuring this protection. However, what happens when their resources to cope with a flood are at stake or the intensity and frequency of the event exceeds their capacities? Many cities in the Free State of Saxony, Germany, were strongly hit by several floods in the last years and are additionally challenged by demographic change, with an ageing society and out-migration leading to population shrinkage in many parts of Saxony. Disaster management, which is mostly volunteer-based in Germany, is particularly affected by this change, leading to a loss of members. We propose an agent-based simulation model that acts as a "virtual lab" to explore the impact of various changes on disaster management performance. Using different scenarios we examine the impact of changes in personal resources of DMOs, their access to operation relevant information, flood characteristics as well as differences between geographic regions. A loss of DMOs and associated manpower caused by demographic change has the most profound impact on the performance. Especially in rural, upstream regions population decline in combination with very short lead times can put disaster management performance at risk.

  15. SU-D-9A-02: Relative Effects of Threshold Choice and Spatial Resolution Modeling On SUV and Volume Quantification in F18-FDG PET Imaging of Anal Cancer Patients

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, F [Duke University Medical Center, Durham, NC (United States); Shandong Cancer Hospital and Insititute, Jinan, Shandong (China); Bowsher, J; Palta, M; Czito, B; Willett, C; Yin, F [Duke University Medical Center, Durham, NC (United States)

    2014-06-01

    Purpose: PET imaging with F18-FDG is utilized for treatment planning, treatment assessment, and prognosis. A region of interest (ROI) encompassing the tumor may be determined on the PET image, often by a threshold T on the PET standard uptake values (SUVs). Several studies have shown prognostic value for relevant ROI properties including maximum SUV value (SUVmax), metabolic tumor volume (MTV), and total glycolytic activity (TGA). The choice of threshold T may affect mean SUV value (SUVmean), MTV, and TGA. Recently spatial resolution modeling (SRM) has been introduced on many PET systems. SRM may also affect these ROI properties. The purpose of this work is to investigate the relative influence of SRM and threshold choice T on SUVmean, MTV, TGA, and SUVmax. Methods: For 9 anal cancer patients, 18F-FDG PET scans were performed prior to treatment. PET images were reconstructed by 2 iterations of Ordered Subsets Expectation Maximization (OSEM), with and without SRM. ROI contours were generated by 5 different SUV threshold values T: 2.5, 3.0, 30%, 40%, and 50% of SUVmax. Paired-samples t tests were used to compare SUVmean, MTV, and TGA (a) for SRM on versus off and (b) between each pair of threshold values T. SUVmax was also compared for SRM on versus off. Results: For almost all (57/60) comparisons of 2 different threshold values, SUVmean, MTV, and TGA showed statistically significant variation. For comparison of SRM on versus off, there were no statistically significant changes in SUVmax and TGA, but there were statistically significant changes in MTV for T=2.5 and T=3.0 and in SUVmean for all T. Conclusion: The near-universal statistical significance of threshold choice T suggests that, regarding harmonization across sites, threshold choice may be a greater concern than choice of SRM. However, broader study is warranted, e.g. other iterations of OSEM should be considered.

  16. SU-D-9A-02: Relative Effects of Threshold Choice and Spatial Resolution Modeling On SUV and Volume Quantification in F18-FDG PET Imaging of Anal Cancer Patients

    International Nuclear Information System (INIS)

    Zhao, F; Bowsher, J; Palta, M; Czito, B; Willett, C; Yin, F

    2014-01-01

    Purpose: PET imaging with F18-FDG is utilized for treatment planning, treatment assessment, and prognosis. A region of interest (ROI) encompassing the tumor may be determined on the PET image, often by a threshold T on the PET standard uptake values (SUVs). Several studies have shown prognostic value for relevant ROI properties including maximum SUV value (SUVmax), metabolic tumor volume (MTV), and total glycolytic activity (TGA). The choice of threshold T may affect mean SUV value (SUVmean), MTV, and TGA. Recently spatial resolution modeling (SRM) has been introduced on many PET systems. SRM may also affect these ROI properties. The purpose of this work is to investigate the relative influence of SRM and threshold choice T on SUVmean, MTV, TGA, and SUVmax. Methods: For 9 anal cancer patients, 18F-FDG PET scans were performed prior to treatment. PET images were reconstructed by 2 iterations of Ordered Subsets Expectation Maximization (OSEM), with and without SRM. ROI contours were generated by 5 different SUV threshold values T: 2.5, 3.0, 30%, 40%, and 50% of SUVmax. Paired-samples t tests were used to compare SUVmean, MTV, and TGA (a) for SRM on versus off and (b) between each pair of threshold values T. SUVmax was also compared for SRM on versus off. Results: For almost all (57/60) comparisons of 2 different threshold values, SUVmean, MTV, and TGA showed statistically significant variation. For comparison of SRM on versus off, there were no statistically significant changes in SUVmax and TGA, but there were statistically significant changes in MTV for T=2.5 and T=3.0 and in SUVmean for all T. Conclusion: The near-universal statistical significance of threshold choice T suggests that, regarding harmonization across sites, threshold choice may be a greater concern than choice of SRM. However, broader study is warranted, e.g. other iterations of OSEM should be considered

  17. Conflict Resolution as Near-Threshold Decision-Making: A Spiking Neural Circuit Model with Two-Stage Competition for Antisaccadic Task.

    Directory of Open Access Journals (Sweden)

    Chung-Chuan Lo

    2016-08-01

    Full Text Available Automatic responses enable us to react quickly and effortlessly, but they often need to be inhibited so that an alternative, voluntary action can take place. To investigate the brain mechanism of controlled behavior, we investigated a biologically-based network model of spiking neurons for inhibitory control. In contrast to a simple race between pro- versus anti-response, our model incorporates a sensorimotor remapping module, and an action-selection module endowed with a "Stop" process through tonic inhibition. Both are under the modulation of rule-dependent control. We tested the model by applying it to the well known antisaccade task in which one must suppress the urge to look toward a visual target that suddenly appears, and shift the gaze diametrically away from the target instead. We found that the two-stage competition is crucial for reproducing the complex behavior and neuronal activity observed in the antisaccade task across multiple brain regions. Notably, our model demonstrates two types of errors: fast and slow. Fast errors result from failing to inhibit the quick automatic responses and therefore exhibit very short response times. Slow errors, in contrast, are due to incorrect decisions in the remapping process and exhibit long response times comparable to those of correct antisaccade responses. The model thus reveals a circuit mechanism for the empirically observed slow errors and broad distributions of erroneous response times in antisaccade. Our work suggests that selecting between competing automatic and voluntary actions in behavioral control can be understood in terms of near-threshold decision-making, sharing a common recurrent (attractor neural circuit mechanism with discrimination in perception.

  18. A Bayesian changepoint-threshold model to examine the effect of TMDL implementation on the flow-nitrogen concentration relationship in the Neuse River basin.

    Science.gov (United States)

    Alameddine, Ibrahim; Qian, Song S; Reckhow, Kenneth H

    2011-01-01

    In-stream nutrient concentrations are well known to exhibit a strong relationship with river flow. The use of flow measurements to predict nutrient concentrations and subsequently nutrient loads is common in water quality modeling. Nevertheless, most adopted models assume that the relationship between flow and concentration is fixed across time as well as across different flow regimes. In this study, we developed a Bayesian changepoint-threshold model that relaxes these constraints and allows for the identification and quantification of any changes in the underlying flow-concentration relationship across time. The results from our study support the occurrence of a changepoint in time around the year 1999, which coincided with the period of implementing nitrogen control measures as part of the TMDL program developed for the Neuse Estuary in North Carolina. The occurrence of the changepoint challenges the underlying assumption of temporal invariance in the flow-concentrations relationship. The model results also point towards a transition in the river nitrogen delivery system from a point source dominated loading system towards a more complicated nonlinear system, where non-point source nutrient delivery plays a major role. Moreover, we use the developed model to assess the effectiveness of the nitrogen reduction measures in achieving a 30% drop in loading. The results indicate that while there is a strong evidence of a load reduction, there still remains a high level of uncertainty associated with the mean nitrogen load reduction. We show that the level of uncertainty around the estimated load reduction is not random but is flow related. Copyright © 2010 Elsevier Ltd. All rights reserved.

  19. Pion photoproduction on the nucleon at threshold

    International Nuclear Information System (INIS)

    Cheon, I.T.; Jeong, M.T.

    1989-08-01

    Electric dipole amplitudes of pion photoproduction on the nucleon at threshold have been calculated in the framework of the chiral bag model. Our results are in good agreement with the existing experimental data

  20. Secure information management using linguistic threshold approach

    CERN Document Server

    Ogiela, Marek R

    2013-01-01

    This book details linguistic threshold schemes for information sharing. It examines the opportunities of using these techniques to create new models of managing strategic information shared within a commercial organisation or a state institution.

  1. Protocol for the specialist supervised individualised multifactorial treatment of new clinically diagnosed type 2 diabetes in general practice (IDA)

    DEFF Research Database (Denmark)

    Stidsen, Jacob Volmer; Nielsen, Jens Steen; Henriksen, Jan Erik

    2017-01-01

    INTRODUCTION: We present the protocol for a multifactorial intervention study designed to test whether individualised treatment, based on pathophysiological phenotyping and individualised treatment goals, improves type 2 diabetes (T2D) outcomes. METHODS AND ANALYSIS: We will conduct a prospective...

  2. Threshold guidance update

    International Nuclear Information System (INIS)

    Wickham, L.E.

    1986-01-01

    The Department of Energy (DOE) is developing the concept of threshold quantities for use in determining which waste materials must be handled as radioactive waste and which may be disposed of as nonradioactive waste at its sites. Waste above this concentration level would be managed as radioactive or mixed waste (if hazardous chemicals are present); waste below this level would be handled as sanitary waste. Last years' activities (1984) included the development of a threshold guidance dose, the development of threshold concentrations corresponding to the guidance dose, the development of supporting documentation, review by a technical peer review committee, and review by the DOE community. As a result of the comments, areas have been identified for more extensive analysis, including an alternative basis for selection of the guidance dose and the development of quality assurance guidelines. Development of quality assurance guidelines will provide a reasonable basis for determining that a given waste stream qualifies as a threshold waste stream and can then be the basis for a more extensive cost-benefit analysis. The threshold guidance and supporting documentation will be revised, based on the comments received. The revised documents will be provided to DOE by early November. DOE-HQ has indicated that the revised documents will be available for review by DOE field offices and their contractors

  3. Does a population-based multifactorial lifestyle intervention increase social inequality in physical activity? The Inter99 study

    DEFF Research Database (Denmark)

    Aadahl, M; Smith, L von Huth; Toft, U

    2011-01-01

    Aim To examine the effect of a multifactorial lifestyle intervention on 5-year change in physical activity (PA) and to explore whether length of education had an impact on the effect of the intervention. Methods Two random samples (high intervention group A, n=11 708; low intervention group B, n......-based multifactorial lifestyle intervention did not influence social inequality in PA. Keywords Lifestyle, Exercise, Randomised Intervention Study, Ischemic Heart Disease, Socioeconomic Position....

  4. Multifactorial assessment and targeted intervention to reduce falls among the oldest-old: a randomized controlled trial

    Directory of Open Access Journals (Sweden)

    Ferrer A

    2014-02-01

    Full Text Available Assumpta Ferrer,1 Francesc Formiga,2,3 Héctor Sanz,4 Oscar J de Vries,5 Teresa Badia,6 Ramón Pujol2,3 On behalf of the OCTABAIX Study Group 1Primary Healthcare Centre "El Plà" CAP-I, Sant Feliu de Llobregat, 2Geriatric Unit, Internal Medicine Service, Hospital Universitari de Bellvitge, 3Bellvitge Biomedical Research Institute, IDIBELL, L'Hospitalet de Llobregat, 4Support Research Unit, Primary Health Department Costa Ponent, IDIAP Jordi Gol, Barcelona, Spain; 5Department of Internal Medicine, VU University Medical Center, Amsterdam, the Netherlands; 6Primary Healthcare Centre Martorell, Barcelona, Spain Background: The purpose of this study was to assess the effectiveness of a multifactorial intervention to reduce falls among the oldest-old people, including individuals with cognitive impairment or comorbidities. Methods: A randomized, single-blind, parallel-group clinical trial was conducted from January 2009 to December 2010 in seven primary health care centers in Baix Llobregat (Barcelona. Of 696 referred people who were born in 1924, 328 were randomized to an intervention group or a control group. The intervention model used an algorithm and was multifaceted for both patients and their primary care providers. Primary outcomes were risk of falling and time until falls. Data analyses were by intention-to-treat. Results: Sixty-five (39.6% subjects in the intervention group and 48 (29.3% in the control group fell during follow-up. The difference in the risk of falls was not significant (relative risk 1.28, 95% confidence interval [CI] 0.94–1.75. Cox regression models with time from randomization to the first fall were not significant. Cox models for recurrent falls showed that intervention had a negative effect (hazard ratio [HR] 1.46, 95% CI 1.03–2.09 and that functional impairment (HR 1.42, 95% CI 0.97–2.12, previous falls (HR 1.09, 95% CI 0.74–1.60, and cognitive impairment (HR 1.08, 95% CI 0.72–1.60 had no effect on the

  5. Near threshold fatigue testing

    Science.gov (United States)

    Freeman, D. C.; Strum, M. J.

    1993-01-01

    Measurement of the near-threshold fatigue crack growth rate (FCGR) behavior provides a basis for the design and evaluation of components subjected to high cycle fatigue. Typically, the near-threshold fatigue regime describes crack growth rates below approximately 10(exp -5) mm/cycle (4 x 10(exp -7) inch/cycle). One such evaluation was recently performed for the binary alloy U-6Nb. The procedures developed for this evaluation are described in detail to provide a general test method for near-threshold FCGR testing. In particular, techniques for high-resolution measurements of crack length performed in-situ through a direct current, potential drop (DCPD) apparatus, and a method which eliminates crack closure effects through the use of loading cycles with constant maximum stress intensity are described.

  6. Clinical multiple sclerosis occurs at one end of a spectrum of CNS pathology: a modified threshold liability model leads to new ways of thinking about the cause of clinical multiple sclerosis.

    Science.gov (United States)

    Haegert, David G

    2005-01-01

    Multiple sclerosis (MS) is a complex trait, the causes of which are elusive. A threshold liability model influences thinking about the causes of this disorder. According to this model, a population has a normal distribution of genetic liability to MS. In addition, a threshold exists, so that MS begins when an individual's liability exceeds the MS threshold; environmental and other causative factors may increase or decrease an individual's MS liability. It is argued here, however, that this model is misleading, as it is based on the incorrect assumption that MS is a disorder that one either has or does not have. This paper hypothesizes, instead, that patients with a diagnosis of MS share identical CNS pathology, termed MS pathology, with some individuals who have a diagnosis of possible MS and with some apparently healthy individuals, who may never have a diagnosis of MS. In order to accommodate this hypothesis, the current threshold liability model is modified as follows. (1) In addition to a normal distribution of MS liability within a population, a spectrum of MS pathology occurs in some who have a high MS liability. (2) A clinical MS threshold exists at a point on this liability distribution, where the burden and distribution of MS pathology permits a diagnosis of clinical MS. (3) Additional thresholds exist that correspond to a lower MS liability and a lesser burden of MS pathology than occur at the clinical MS threshold. This modified threshold model leads to the postulate that causes act at various time points to increase MS liability and induce MS pathology. The accumulation of MS pathology sometimes leads to a diagnosis of clinical MS. One implication of this model is that the MS pathology in clinical MS and in some with possible MS differs only in the extent but not in the type of CNS injury. Thus, it may be possible to obtain insight into the causative environmental factors that increase MS liability and induce MS pathology by focusing on patients who

  7. Cost-effectiveness of nurse-led multifactorial care to prevent or postpone new disabilities in community-living older people: Results of a cluster randomized trial.

    Science.gov (United States)

    Suijker, Jacqueline J; MacNeil-Vroomen, Janet L; van Rijn, Marjon; Buurman, Bianca M; de Rooij, Sophia E; Moll van Charante, Eric P; Bosmans, Judith E

    2017-01-01

    To evaluate the cost-effectiveness of nurse-led multifactorial care to prevent or postpone new disabilities in community-living older people in comparison with usual care. We conducted cost-effectiveness and cost-utility analyses alongside a cluster randomized trial with one-year follow-up. Participants were aged ≥ 70 years and at increased risk of functional decline. Participants in the intervention group (n = 1209) received a comprehensive geriatric assessment and individually tailored multifactorial interventions coordinated by a community-care registered nurse with multiple follow-up visits. The control group (n = 1074) received usual care. Costs were assessed from a healthcare perspective. Outcome measures included disability (modified Katz-Activities of Daily Living (ADL) index score), and quality-adjusted life-years (QALYs). Statistical uncertainty surrounding Incremental Cost-Effectiveness Ratios (ICERs) was estimated using bootstrapped bivariate regression models while adjusting for confounders. There were no statistically significant differences in Katz-ADL index score and QALYs between the two groups. Total mean costs were significantly higher in the intervention group (EUR 6518 (SE 472) compared with usual care (EUR 5214 (SE 338); adjusted mean difference €1457 (95% CI: 572; 2537). Cost-effectiveness acceptability curves showed that the maximum probability of the intervention being cost-effective was 0.14 at a willingness to pay (WTP) of EUR 50,000 per one point improvement on the Katz-ADL index score and 0.04 at a WTP of EUR 50,000 per QALY gained. The current intervention was not cost-effective compared to usual care to prevent or postpone new disabilities over a one-year period. Based on these findings, implementation of the evaluated multifactorial nurse-led care model is not to be recommended.

  8. Defining the biomechanical and biological threshold of murine mild traumatic brain injury using CHIMERA (Closed Head Impact Model of Engineered Rotational Acceleration).

    Science.gov (United States)

    Namjoshi, Dhananjay R; Cheng, Wai Hang; Bashir, Asma; Wilkinson, Anna; Stukas, Sophie; Martens, Kris M; Whyte, Tom; Abebe, Zelalem A; McInnes, Kurt A; Cripton, Peter A; Wellington, Cheryl L

    2017-06-01

    CHIMERA (Closed Head Impact Model of Engineered Rotational Acceleration) is a recently described animal model of traumatic brain injury (TBI) that primarily produces diffuse axonal injury (DAI) characterized by white matter inflammation and axonal damage. CHIMERA was specifically designed to reliably generate a variety of TBI severities using precise and quantifiable biomechanical inputs in a nonsurgical user-friendly platform. The objective of this study was to define the lower limit of single impact mild TBI (mTBI) using CHIMERA by characterizing the dose-response relationship between biomechanical input and neurological, behavioral, neuropathological and biochemical outcomes. Wild-type male mice were subjected to a single CHIMERA TBI using six impact energies ranging from 0.1 to 0.7J, and post-TBI outcomes were assessed over an acute period of 14days. Here we report that single TBI using CHIMERA induces injury dose- and time-dependent changes in behavioral and neurological deficits, axonal damage, white matter tract microgliosis and astrogliosis. Impact energies of 0.4J or below produced no significant phenotype (subthreshold), 0.5J led to significant changes for one or more phenotypes (threshold), and 0.6 and 0.7J resulted in significant changes in all outcomes assessed (mTBI). We further show that linear head kinematics are the most robust predictors of duration of unconsciousness, severity of neurological deficits, white matter injury, and microgliosis following single TBI. Our data extend the validation of CHIMERA as a biofidelic animal model of DAI and establish working parameters to guide future investigations of the mechanisms underlying axonal pathology and inflammation induced by mechanical trauma. Crown Copyright © 2017. Published by Elsevier Inc. All rights reserved.

  9. 4D stress evolution models of the San Andreas Fault System: Investigating time- and depth-dependent stress thresholds over multiple earthquake cycles

    Science.gov (United States)

    Burkhard, L. M.; Smith-Konter, B. R.

    2017-12-01

    4D simulations of stress evolution provide a rare insight into earthquake cycle crustal stress variations at seismogenic depths where earthquake ruptures nucleate. Paleoseismic estimates of earthquake offset and chronology, spanning multiple earthquakes cycles, are available for many well-studied segments of the San Andreas Fault System (SAFS). Here we construct new 4D earthquake cycle time-series simulations to further study the temporally and spatially varying stress threshold conditions of the SAFS throughout the paleoseismic record. Interseismic strain accumulation, co-seismic stress drop, and postseismic viscoelastic relaxation processes are evaluated as a function of variable slip and locking depths along 42 major fault segments. Paleoseismic earthquake rupture histories provide a slip chronology dating back over 1000 years. Using GAGE Facility GPS and new Sentinel-1A InSAR data, we tune model locking depths and slip rates to compute the 4D stress accumulation within the seismogenic crust. Revised estimates of stress accumulation rate are most significant along the Imperial (2.8 MPa/100yr) and Coachella (1.2 MPa/100yr) faults, with a maximum change in stress rate along some segments of 11-17% in comparison with our previous estimates. Revised estimates of earthquake cycle stress accumulation are most significant along the Imperial (2.25 MPa), Coachella (2.9 MPa), and Carrizo (3.2 MPa) segments, with a 15-29% decrease in stress due to locking depth and slip rate updates, and also postseismic relaxation from the El Mayor-Cucapah earthquake. Because stress drops of major strike-slip earthquakes rarely exceed 10 MPa, these models may provide a lower bound on estimates of stress evolution throughout the historical era, and perhaps an upper bound on the expected recurrence interval of a particular fault segment. Furthermore, time-series stress models reveal temporally varying stress concentrations at 5-10 km depths, due to the interaction of neighboring fault

  10. Identification of Molecular Fingerprints in Human Heat Pain Thresholds by Use of an Interactive Mixture Model R Toolbox (AdaptGauss).

    Science.gov (United States)

    Ultsch, Alfred; Thrun, Michael C; Hansen-Goos, Onno; Lötsch, Jörn

    2015-10-28

    Biomedical data obtained during cell experiments, laboratory animal research, or human studies often display a complex distribution. Statistical identification of subgroups in research data poses an analytical challenge. Here were introduce an interactive R-based bioinformatics tool, called "AdaptGauss". It enables a valid identification of a biologically-meaningful multimodal structure in the data by fitting a Gaussian mixture model (GMM) to the data. The interface allows a supervised selection of the number of subgroups. This enables the expectation maximization (EM) algorithm to adapt more complex GMM than usually observed with a noninteractive approach. Interactively fitting a GMM to heat pain threshold data acquired from human volunteers revealed a distribution pattern with four Gaussian modes located at temperatures of 32.3, 37.2, 41.4, and 45.4 °C. Noninteractive fitting was unable to identify a meaningful data structure. Obtained results are compatible with known activity temperatures of different TRP ion channels suggesting the mechanistic contribution of different heat sensors to the perception of thermal pain. Thus, sophisticated analysis of the modal structure of biomedical data provides a basis for the mechanistic interpretation of the observations. As it may reflect the involvement of different TRP thermosensory ion channels, the analysis provides a starting point for hypothesis-driven laboratory experiments.

  11. Cost-effectiveness of intensive multifactorial treatment compared with routine care for individuals with screen-detected Type 2 diabetes: analysis of the ADDITION-UK cluster-randomized controlled trial

    Science.gov (United States)

    Tao, L; Wilson, E C F; Wareham, N J; Sandbæk, A; Rutten, G E H M; Lauritzen, T; Khunti, K; Davies, M J; Borch-Johnsen, K; Griffin, S J; Simmons, R K

    2015-01-01

    Aims To examine the short- and long-term cost-effectiveness of intensive multifactorial treatment compared with routine care among people with screen-detected Type 2 diabetes. Methods Cost–utility analysis in ADDITION-UK, a cluster-randomized controlled trial of early intensive treatment in people with screen-detected diabetes in 69 UK general practices. Unit treatment costs and utility decrement data were taken from published literature. Accumulated costs and quality-adjusted life years (QALYs) were calculated using ADDITION-UK data from 1 to 5 years (short-term analysis, n = 1024); trial data were extrapolated to 30 years using the UKPDS outcomes model (version 1.3) (long-term analysis; n = 999). All costs were transformed to the UK 2009/10 price level. Results Adjusted incremental costs to the NHS were £285, £935, £1190 and £1745 over a 1-, 5-, 10- and 30-year time horizon, respectively (discounted at 3.5%). Adjusted incremental QALYs were 0.0000, – 0.0040, 0.0140 and 0.0465 over the same time horizons. Point estimate incremental cost-effectiveness ratios (ICERs) suggested that the intervention was not cost-effective although the ratio improved over time: the ICER over 10 years was £82 250, falling to £37 500 over 30 years. The ICER fell below £30 000 only when the intervention cost was below £631 per patient: we estimated the cost at £981. Conclusion Given conventional thresholds of cost-effectiveness, the intensive treatment delivered in ADDITION was not cost-effective compared with routine care for individuals with screen-detected diabetes in the UK. The intervention may be cost-effective if it can be delivered at reduced cost. PMID:25661661

  12. Threshold factorization redux

    Science.gov (United States)

    Chay, Junegone; Kim, Chul

    2018-05-01

    We reanalyze the factorization theorems for the Drell-Yan process and for deep inelastic scattering near threshold, as constructed in the framework of the soft-collinear effective theory (SCET), from a new, consistent perspective. In order to formulate the factorization near threshold in SCET, we should include an additional degree of freedom with small energy, collinear to the beam direction. The corresponding collinear-soft mode is included to describe the parton distribution function (PDF) near threshold. The soft function is modified by subtracting the contribution of the collinear-soft modes in order to avoid double counting on the overlap region. As a result, the proper soft function becomes infrared finite, and all the factorized parts are free of rapidity divergence. Furthermore, the separation of the relevant scales in each factorized part becomes manifest. We apply the same idea to the dihadron production in e+e- annihilation near threshold, and show that the resultant soft function is also free of infrared and rapidity divergences.

  13. A distribution-free multi-factorial profiler for harvesting information from high-density screenings.

    Science.gov (United States)

    Besseris, George J

    2013-01-01

    Data screening is an indispensable phase in initiating the scientific discovery process. Fractional factorial designs offer quick and economical options for engineering highly-dense structured datasets. Maximum information content is harvested when a selected fractional factorial scheme is driven to saturation while data gathering is suppressed to no replication. A novel multi-factorial profiler is presented that allows screening of saturated-unreplicated designs by decomposing the examined response to its constituent contributions. Partial effects are sliced off systematically from the investigated response to form individual contrasts using simple robust measures. By isolating each time the disturbance attributed solely to a single controlling factor, the Wilcoxon-Mann-Whitney rank stochastics are employed to assign significance. We demonstrate that the proposed profiler possesses its own self-checking mechanism for detecting a potential influence due to fluctuations attributed to the remaining unexplainable error. Main benefits of the method are: 1) easy to grasp, 2) well-explained test-power properties, 3) distribution-free, 4) sparsity-free, 5) calibration-free, 6) simulation-free, 7) easy to implement, and 8) expanded usability to any type and size of multi-factorial screening designs. The method is elucidated with a benchmarked profiling effort for a water filtration process.

  14. A distribution-free multi-factorial profiler for harvesting information from high-density screenings.

    Directory of Open Access Journals (Sweden)

    George J Besseris

    Full Text Available Data screening is an indispensable phase in initiating the scientific discovery process. Fractional factorial designs offer quick and economical options for engineering highly-dense structured datasets. Maximum information content is harvested when a selected fractional factorial scheme is driven to saturation while data gathering is suppressed to no replication. A novel multi-factorial profiler is presented that allows screening of saturated-unreplicated designs by decomposing the examined response to its constituent contributions. Partial effects are sliced off systematically from the investigated response to form individual contrasts using simple robust measures. By isolating each time the disturbance attributed solely to a single controlling factor, the Wilcoxon-Mann-Whitney rank stochastics are employed to assign significance. We demonstrate that the proposed profiler possesses its own self-checking mechanism for detecting a potential influence due to fluctuations attributed to the remaining unexplainable error. Main benefits of the method are: 1 easy to grasp, 2 well-explained test-power properties, 3 distribution-free, 4 sparsity-free, 5 calibration-free, 6 simulation-free, 7 easy to implement, and 8 expanded usability to any type and size of multi-factorial screening designs. The method is elucidated with a benchmarked profiling effort for a water filtration process.

  15. Perspective: Uses and misuses of thresholds in diagnostic decision making.

    Science.gov (United States)

    Warner, Jeremy L; Najarian, Robert M; Tierney, Lawrence M

    2010-03-01

    The concept of thresholds plays a vital role in decisions involving the initiation, continuation, and completion of diagnostic testing. Much research has focused on the development of explicit thresholds, in the form of practice guidelines and decision analyses. However, these tools are used infrequently; most medical decisions are made at the bedside, using implicit thresholds. Study of these thresholds can lead to a deeper understanding of clinical decision making. The authors examine some factors constituting individual clinicians' implicit thresholds. They propose a model for static thresholds using the concept of situational gravity to explain why some thresholds are high, and some low. Next, they consider the hypothetical effects of incorrect placement of thresholds (miscalibration) and changes to thresholds during diagnosis (manipulation). They demonstrate these concepts using common clinical scenarios. Through analysis of miscalibration of thresholds, the authors demonstrate some common maladaptive clinical behaviors, which are nevertheless internally consistent. They then explain how manipulation of thresholds gives rise to common cognitive heuristics including premature closure and anchoring. They also discuss the case where no threshold has been exceeded despite exhaustive collection of data, which commonly leads to application of the availability or representativeness heuristics. Awareness of implicit thresholds allows for a more effective understanding of the processes of medical decision making and, possibly, to the avoidance of detrimental heuristics and their associated medical errors. Research toward accurately defining these thresholds for individual physicians and toward determining their dynamic properties during the diagnostic process may yield valuable insights.

  16. When Do Price Thresholds Matter in Retail Categories?

    OpenAIRE

    Koen Pauwels; Shuba Srinivasan; Philip Hans Franses

    2007-01-01

    Marketing literature has long recognized that brand price elasticity need not be monotonic and symmetric, but has yet to provide generalizable market-level insights on threshold-based price elasticity, asymmetric thresholds, and the sign and magnitude of elasticity transitions. This paper introduces smooth transition regression models to study threshold-based price elasticity of the top 4 brands across 20 fast-moving consumer good categories. Threshold-based price elasticity is found for 76% ...

  17. When do price thresholds matter in retail categories?

    OpenAIRE

    Pauwels, Koen; Srinivasan, Shuba; Franses, Philip Hans

    2007-01-01

    textabstractMarketing literature has long recognized that brand price elasticity need not be monotonic and symmetric, but has yet to provide generalizable market-level insights on threshold-based price elasticity, asymmetric thresholds, and the sign and magnitude of elasticity transitions. This paper introduces smooth transition regression models to study threshold-based price elasticity of the top 4 brands across 20 fast-moving consumer good categories. Threshold-based price elasticity is fo...

  18. Estimating the Threshold Level of Inflation for Thailand

    OpenAIRE

    Jiranyakul, Komain

    2017-01-01

    Abstract. This paper analyzes the relationship between inflation and economic growth in Thailand using annual dataset during 1990 and 2015. The threshold model is estimated for different levels of threshold inflation rate. The results suggest that the threshold level of inflation above which inflation significantly slow growth is estimated at 3 percent. The negative relationship between inflation and growth is apparent above this threshold level of inflation. In other words, the inflation rat...

  19. Deterministic estimation of hydrological thresholds for shallow landslide initiation and slope stability models: case study from the Somma-Vesuvius area of southern Italy

    Science.gov (United States)

    Baum, Rex L.; Godt, Jonathan W.; De Vita, P.; Napolitano, E.

    2012-01-01

    interrupted. These results lead to the identification of a comprehensive hydrogeomorphological model of susceptibility to initial landslides that links morphological, stratigraphical and hydrological conditions. The calculation of intensities and durations of rainfall necessary for slope instability allowed the identification of deterministic hydrological thresholds that account for uncertainty in properties and observed rainfall intensities.

  20. Hadron production near threshold

    Indian Academy of Sciences (India)

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

  1. Casualties and threshold effects

    International Nuclear Information System (INIS)

    Mays, C.W.; National Cancer Inst., Bethesda

    1988-01-01

    Radiation effects like cancer are denoted as casualties. Other radiation effects occur almost in everyone when the radiation dose is sufficiently high. One then speaks of radiation effects with a threshold dose. In this article the author puts his doubt about this classification of radiation effects. He argues that some effects of exposure to radiation do not fit in this classification. (H.W.). 19 refs.; 2 figs.; 1 tab

  2. Resonance phenomena near thresholds

    International Nuclear Information System (INIS)

    Persson, E.; Mueller, M.; Rotter, I.; Technische Univ. Dresden

    1995-12-01

    The trapping effect is investigated close to the elastic threshold. The nucleus is described as an open quantum mechanical many-body system embedded in the continuum of decay channels. An ensemble of compound nucleus states with both discrete and resonance states is investigated in an energy-dependent formalism. It is shown that the discrete states can trap the resonance ones and also that the discrete states can directly influence the scattering cross section. (orig.)

  3. Radiation risk of individual multifactorial diseases in offspring of the atomic-bomb survivors: a clinical health study

    International Nuclear Information System (INIS)

    Tatsukawa, Yoshimi; Yamada, Michiko; Ohishi, Waka; Hida, Ayumi; Akahoshi, Masazumi; Fujiwara, Saeko; Cologne, John B; Hsu, Wan-Ling; Furukawa, Kyoji; Takahashi, Norio; Nakamura, Nori; Suyama, Akihiko; Ozasa, Kotaro; Shore, Roy

    2013-01-01

    There is no convincing evidence regarding radiation-induced heritable risks of adult-onset multifactorial diseases in humans, although it is important from the standpoint of protection and management of populations exposed to radiation. The objective of the present study was to examine whether parental exposure to atomic-bomb (A-bomb) radiation led to an increased risk of common polygenic, multifactorial diseases—hypertension, hypercholesterolaemia, diabetes mellitus, angina pectoris, myocardial infarction or stroke—in the first-generation (F 1 ) offspring of A-bomb survivors. A total of 11 951 F 1 offspring of survivors in Hiroshima or Nagasaki, conceived after the bombing, underwent health examinations to assess disease prevalence. We found no evidence that paternal or maternal A-bomb radiation dose, or the sum of their doses, was associated with an increased risk of any multifactorial diseases in either male or female offspring. None of the 18 radiation dose–response slopes, adjusted for other risk factors for the diseases, was statistically significantly elevated. However, the study population is still in mid-life (mean age 48.6 years), and will express much of its multifactorial disease incidence in the future, so ongoing longitudinal follow-up will provide increasingly informative risk estimates regarding hereditary genetic effects for incidence of adult-onset multifactorial disease. (paper)

  4. Simple physical-empirical model of the precipitation distribution based on a tropical sea surface temperature threshold and the effects of climate change

    Science.gov (United States)

    Jauregui, Yakelyn R.; Takahashi, Ken

    2018-03-01

    The observed nonlinear relationship between tropical sea surface temperature (T_s) and precipitation ( P) on climate timescales, by which a threshold (T_c) must be exceeded by T_s in order for deep convection to occur, is the basis of a physical-empirical model (PEM) that we fitted to observational data and CMIP5 climate model output and used to show that, with essentially only two constant parameters (T_c and the sensitivity a_1 of P to T_s>T_c), it provides a useful first-order description of the climatological and interannual variability of the large-scale distribution of tropical P given T_s, as well as of the biases of the Global Climate Models (GCMs). A substantial limitation is its underestimation of the peak P in the convergence zones, as the necessary processes associated with the atmospheric circulation are not considered. The pattern of the intermodel correlation between the mean T_s-T_c for each GCM and the average P distribution is in agreement with the double ITCZ bias, featuring roughly zonally-symmetric off-equatorial maxima, rather than being regionally or hemispherically restricted. The inter-comparison of GCMs indicates a relationship between T_c with the near-equatorial low-level (850 hPa) tropospheric temperature, consistent with the interpretation that it is a measure of the convective inhibition (CIN). The underestimation of T_c is linked to the cold free tropospheric bias in the GCMs. However, the discrepancy among the observational datasets is a limitation for assessing the GCM biases from the PEM framework quantitatively. Under the RCP4.5 climate change scenario, T_c increases slightly more than the mean tropical T_s, implying a stabilizing trend consistent with the amplified free tropospheric warming relative to the surface. However, since a_1 increases by 10-50%/°C with the surface warming, its effect dominates and results in generally positive precipitation change (Δ P) in the equatorial regions. In the equatorial eastern

  5. An outpatient multifactorial falls prevention intervention does not reduce falls in high-risk elderly Danes

    DEFF Research Database (Denmark)

    Vind, Ane B; Andersen, Hanne E; Pedersen, Kirsten D

    2009-01-01

    , mean age 74, 73.7%women, who had visited the emergency department or had been hospitalized due to a fall. INTERVENTION: Identification of general medical, cardiovascular, and physical risk factors for falls and individual intervention in the intervention group. Participants in the control group....... Followup exceeded 90.0%. A total of 422 falls were registered in the intervention group, 398 in the control group. Intention-to-treat analysis revealed no effect of the intervention on fall rates (relative risk=1.06, 95%confidence interval (CI)=0.75 -1.51), proportion with falls (odds ratio (OR)=1.20, 95......OBJECTIVES: To evaluate the effect of multifactorial fall prevention in community-dwelling people aged 65 and older in Denmark. DESIGN: Randomized, controlled clinical trial. SETTING: Geriatric outpatient clinic at Glostrup University Hospital. PARTICIPANTS: Three hundred ninety-two elderly people...

  6. Multifactorial optimization of the decolorisation parameters of wastewaters resulting from dyeing flowers.

    Science.gov (United States)

    Pavas, Edison Gil; Gómez-García, Miguel Angel

    2009-01-01

    This work deals with the treatment of the wastewaters resulting from the process of dyeing flowers. In some local cases for growing flowers near to Medellín (Colombia), wastewater color was found to be one of the main problems in meeting local effluent standards. Wastewaters were treated by photodegradation process (which includes photocatalysis) to achieve the degradation of dyes mixture and organic matter in the wastewater. A multifactorial experimental design was proposed, including as experimental factors the following variables: pH, and the concentration of both catalyst (TiO(2)) and hydrogen peroxide (H(2)O(2)). According to the obtained results, at the optimized variables values, it is possible to reach a 99% reduction of dyes, a 76.9% of mineralization (TOC) and a final biodegradability of 0.834. Kinetic analysis allows proposing a pseudo first order reaction for the reduction, the mineralization, and the biodegradation processes.

  7. [Acute inpatient conservative multimodal treatment of complex and multifactorial orthopedic diseases in the ANOA concept].

    Science.gov (United States)

    Psczolla, M

    2013-10-01

    In Germany there is a clear deficit in the non-operative treatment of chronic and complex diseases and pain disorders in acute care hospitals. Only about 20 % of the treatments are carried out in orthopedic hospitals. Hospitals specialized in manual medicine have therefore formed a working group on non-operative orthopedic manual medicine acute care clinics (ANOA). The ANOA has developed a multimodal assessment procedure called the OPS 8-977 which describes the structure and process quality of multimodal and interdisciplinary diagnosis and treatment of the musculoskeletal system. Patients are treated according to clinical pathways oriented on the clinical findings. The increased duration of treatment in the German diagnosis-related groups (DRG) system is compensated for with a supplemental remuneration. Thus, complex and multifactorial orthopedic diseases and pain disorders are conservatively and appropriately treated as inpatient departments of acute care hospitals.

  8. Effect of dissipation on dynamical fusion thresholds

    International Nuclear Information System (INIS)

    Sierk, A.J.

    1986-01-01

    The existence of dynamical thresholds to fusion in heavy nuclei (A greater than or equal to 200) due to the nature of the potential-energy surface is shown. These thresholds exist even in the absence of dissipative forces, due to the coupling between the various collective deformation degrees of freedom. Using a macroscopic model of nuclear shape dynamics, It is shown how three different suggested dissipation mechanisms increase by varying amounts the excitation energy over the one-dimensional barrier required to cause compound-nucleus formation. The recently introduced surface-plus-window dissipation may give a reasonable representation of experimental data on fusion thresholds, in addition to properly describing fission-fragment kinetic energies and isoscalar giant multipole widths. Scaling of threshold results to asymmetric systems is discussed. 48 refs., 10 figs

  9. A Multifactorial, Criteria-based Progressive Algorithm for Hamstring Injury Treatment.

    Science.gov (United States)

    Mendiguchia, Jurdan; Martinez-Ruiz, Enrique; Edouard, Pascal; Morin, Jean-Benoît; Martinez-Martinez, Francisco; Idoate, Fernando; Mendez-Villanueva, Alberto

    2017-07-01

    Given the prevalence of hamstring injuries in football, a rehabilitation program that effectively promotes muscle tissue repair and functional recovery is paramount to minimize reinjury risk and optimize player performance and availability. This study aimed to assess the concurrent effectiveness of administering an individualized and multifactorial criteria-based algorithm (rehabilitation algorithm [RA]) on hamstring injury rehabilitation in comparison with using a general rehabilitation protocol (RP). Implementing a double-blind randomized controlled trial approach, two equal groups of 24 football players (48 total) completed either an RA group or a validated RP group 5 d after an acute hamstring injury. Within 6 months after return to sport, six hamstring reinjuries occurred in RP versus one injury in RA (relative risk = 6, 90% confidence interval = 1-35; clinical inference: very likely beneficial effect). The average duration of return to sport was possibly quicker (effect size = 0.34 ± 0.42) in RP (23.2 ± 11.7 d) compared with RA (25.5 ± 7.8 d) (-13.8%, 90% confidence interval = -34.0% to 3.4%; clinical inference: possibly small effect). At the time to return to sport, RA players showed substantially better 10-m time, maximal sprinting speed, and greater mechanical variables related to speed (i.e., maximum theoretical speed and maximal horizontal power) than the RP. Although return to sport was slower, male football players who underwent an individualized, multifactorial, criteria-based algorithm with a performance- and primary risk factor-oriented training program from the early stages of the process markedly decreased the risk of reinjury compared with a general protocol where long-length strength training exercises were prioritized.

  10. Comparison between intensity- duration thresholds and cumulative rainfall thresholds for the forecasting of landslide

    Science.gov (United States)

    Lagomarsino, Daniela; Rosi, Ascanio; Rossi, Guglielmo; Segoni, Samuele; Catani, Filippo

    2014-05-01

    This work makes a quantitative comparison between the results of landslide forecasting obtained using two different rainfall threshold models, one using intensity-duration thresholds and the other based on cumulative rainfall thresholds in an area of northern Tuscany of 116 km2. The first methodology identifies rainfall intensity-duration thresholds by means a software called MaCumBA (Massive CUMulative Brisk Analyzer) that analyzes rain-gauge records, extracts the intensities (I) and durations (D) of the rainstorms associated with the initiation of landslides, plots these values on a diagram, and identifies thresholds that define the lower bounds of the I-D values. A back analysis using data from past events can be used to identify the threshold conditions associated with the least amount of false alarms. The second method (SIGMA) is based on the hypothesis that anomalous or extreme values of rainfall are responsible for landslide triggering: the statistical distribution of the rainfall series is analyzed, and multiples of the standard deviation (σ) are used as thresholds to discriminate between ordinary and extraordinary rainfall events. The name of the model, SIGMA, reflects the central role of the standard deviations in the proposed methodology. The definition of intensity-duration rainfall thresholds requires the combined use of rainfall measurements and an inventory of dated landslides, whereas SIGMA model can be implemented using only rainfall data. These two methodologies were applied in an area of 116 km2 where a database of 1200 landslides was available for the period 2000-2012. The results obtained are compared and discussed. Although several examples of visual comparisons between different intensity-duration rainfall thresholds are reported in the international literature, a quantitative comparison between thresholds obtained in the same area using different techniques and approaches is a relatively undebated research topic.

  11. Interaction of a Cannabinoid-2 Agonist With Tramadol on Nociceptive Thresholds and Immune Responses in a Rat Model of Incisional Pain.

    Science.gov (United States)

    Stachtari, Chrysoula C; Thomareis, Olympia N; Tsaousi, Georgia G; Karakoulas, Konstantinos A; Chatzimanoli, Foteini I; Chatzopoulos, Stavros A; Vasilakos, Dimitrios G

    The aim of this study was to elucidate the antinociceptive interaction between cannabinoids and tramadol and their impact on proinflammatory response, in terms of serum intereleukin-6 (IL-6) and interleukin-2 (IL-2) release, in a rat model of incisional pain. Prospective randomized trial assessing the individual or combined application of intraperitoneal tramadol (10 mg/kg) and the selective cannabinoid-2 (CB-2) agonist (R,S)-AM1241 (1 mg/kg) applied postsurgical stress stimulus. Pharmacological specificity was established by antagonizing tramadol with naloxone (0.3 mg/kg) and (R,S)-AM1241 with SR144528 (1 mg/kg). Thermal allodynia was assessed by hot plate test 30 (T30), 60 (T60), and 120 (T120) minutes after incision. Blood samples for plasma IL-6 and IL-2 level determination were obtained 2 hours after incision. Data from 42 rats were included in the final analyses. Significant augmentation of thermal threshold was observed at all time points, after administration of either tramadol or (R,S)-AM1241 compared with the control group (P = 0.004 and P = 0.015, respectively). The combination of (R,S)-AM1241 plus tramadol promoted the induced antinociception in an important manner compared with control (P = 0.002) and (R,S)-AM1241 (P = 0.022) groups. Although the antiallodynic effect produced by tramadol was partially reversed by naloxone 30 and 60 minutes after incision (P = 0.028 and P = 0.016, respectively), SR144528 blocked the effects of (R,S)-AM1241 administration in a significant manner (P = 0.001) at all time points. Similarly, naloxone plus SR144528 also blocked the effects of the combination of (R,S)-AM1241 with tramadol at all time points (P = 0.000). IL-6 level in (R,S)-AM1241 plus tramadol group was significantly attenuated compared with control group (P = 0.000). Nevertheless, IL-2 levels remained unchanged in all experimental groups. It seems that the concomitant administration of a selective CB-2 agonist with tramadol in incisional pain model may

  12. Threshold enhancement of diphoton resonances

    CERN Document Server

    Bharucha, Aoife; Goudelis, Andreas

    2016-10-10

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

  13. Sex ratio selection and multi-factorial sex determination in the housefly : A dynamic model

    NARCIS (Netherlands)

    Kozielska, M.A.; Pen, I.R.; Beukeboom, L.W.; Weissing, F.J.

    Sex determining (SD) mechanisms are highly variable between different taxonomic groups and appear to change relatively quickly during evolution. Sex ratio selection could be a dominant force causing such changes. We investigate theoretically the effect of sex ratio selection on the dynamics of a

  14. Intermediate structure and threshold phenomena

    International Nuclear Information System (INIS)

    Hategan, Cornel

    2004-01-01

    The Intermediate Structure, evidenced through microstructures of the neutron strength function, is reflected in open reaction channels as fluctuations in excitation function of nuclear threshold effects. The intermediate state supporting both neutron strength function and nuclear threshold effect is a micro-giant neutron threshold state. (author)

  15. Prediction error variance and expected response to selection, when selection is based on the best predictor - for Gaussian and threshold characters, traits following a Poisson mixed model and survival traits

    DEFF Research Database (Denmark)

    Andersen, Anders Holst; Korsgaard, Inge Riis; Jensen, Just

    2002-01-01

    In this paper, we consider selection based on the best predictor of animal additive genetic values in Gaussian linear mixed models, threshold models, Poisson mixed models, and log normal frailty models for survival data (including models with time-dependent covariates with associated fixed...... or random effects). In the different models, expressions are given (when these can be found - otherwise unbiased estimates are given) for prediction error variance, accuracy of selection and expected response to selection on the additive genetic scale and on the observed scale. The expressions given for non...... Gaussian traits are generalisations of the well-known formulas for Gaussian traits - and reflect, for Poisson mixed models and frailty models for survival data, the hierarchal structure of the models. In general the ratio of the additive genetic variance to the total variance in the Gaussian part...

  16. Crossing the Petawatt threshold

    International Nuclear Information System (INIS)

    Perry, M.

    1996-01-01

    A revolutionary new laser called the Petawatt, developed by Lawrence Livermore researchers after an intensive three-year development effort, has produced more than 1,000 trillion (open-quotes petaclose quotes) watts of power, a world record. By crossing the petawatt threshold, the extraordinarily powerful laser heralds a new age in laser research. Lasers that provide a petawatt of power or more in a picosecond may make it possible to achieve fusion using significantly less energy than currently envisioned, through a novel Livermore concept called open-quotes fast ignition.close quotes The petawatt laser will also enable researchers to study the fundamental properties of matter, thereby aiding the Department of Energy's Stockpile Stewardship efforts and opening entirely new physical regimes to study. The technology developed for the Petawatt has also provided several spinoff technologies, including a new approach to laser material processing

  17. Multifactorial assessment and targeted intervention to reduce falls among the oldest-old: a randomized controlled trial

    NARCIS (Netherlands)

    Ferrer, A.; Formiga, F.; Sanz, H.; de Vries, O.J.; Badia, T.; Pujol, R.

    2014-01-01

    Background: The purpose of this study was to assess the effectiveness of a multifactorial intervention to reduce falls among the oldest-old people, including individuals with cognitive impairment or comorbidities. Methods: A randomized, single-blind, parallel-group clinical trial was conducted from

  18. Effects of Nurse-Led Multifactorial Care to Prevent Disability in Community-Living Older People : Cluster Randomized Trial

    NARCIS (Netherlands)

    Suijker, Jacqueline J.; van Rijn, Marjon; Buurman, Bianca M.; ter Riet, Gerben; van Charante, Eric P. Moll; de Rooij, Sophia E.

    2016-01-01

    Background To evaluate the effects of nurse-led multifactorial care to prevent disability in community-living older people. Methods In a cluster randomized trail, 11 practices (n = 1,209 participants) were randomized to the intervention group, and 13 practices (n = 1,074 participants) were

  19. Stimulated Brillouin scattering threshold in fiber amplifiers

    International Nuclear Information System (INIS)

    Liang Liping; Chang Liping

    2011-01-01

    Based on the wave coupling theory and the evolution model of the critical pump power (or Brillouin threshold) for stimulated Brillouin scattering (SBS) in double-clad fiber amplifiers, the influence of signal bandwidth, fiber-core diameter and amplifier gain on SBS threshold is simulated theoretically. And experimental measurements of SBS are presented in ytterbium-doped double-clad fiber amplifiers with single-frequency hundred nanosecond pulse amplification. Under different input signal pulses, the forward amplified pulse distortion is observed when the pulse energy is up to 660 nJ and the peak power is up to 3.3 W in the pulse amplification with pulse duration of 200 ns and repetition rate of 1 Hz. And the backward SBS narrow pulse appears. The pulse peak power equals to SBS threshold. Good agreement is shown between the modeled and experimental data. (authors)

  20. Amyloid precursor protein and endosomal-lysosomal dysfunction in Alzheimer's disease: inseparable partners in a multifactorial disease.

    Science.gov (United States)

    Nixon, Ralph A

    2017-07-01

    Abnormalities of the endosomal-lysosomal network (ELN) are a signature feature of Alzheimer's disease (AD). These include the earliest known cytopathology that is specific to AD and that affects endosomes and induces the progressive failure of lysosomes, each of which are directly linked by distinct mechanisms to neurodegeneration. The origins of ELN dysfunction and β-amyloidogenesis closely overlap, which reflects their common genetic basis, the established early involvement of endosomes and lysosomes in amyloid precursor protein (APP) processing and clearance, and the pathologic effect of certain APP metabolites on ELN functions. Genes that promote β-amyloidogenesis in AD (APP, PSEN1/2, and APOE4) have primary effects on ELN function. The importance of primary ELN dysfunction to pathogenesis is underscored by the mutations in more than 35 ELN-related genes that, thus far, are known to cause familial neurodegenerative diseases even though different pathogenic proteins may be involved. In this article, I discuss growing evidence that implicates AD gene-driven ELN disruptions as not only the antecedent pathobiology that underlies β-amyloidogenesis but also as the essential partner with APP and its metabolites that drive the development of AD, including tauopathy, synaptic dysfunction, and neurodegeneration. The striking amelioration of diverse deficits in animal AD models by remediating ELN dysfunction further supports a need to integrate APP and ELN relationships, including the role of amyloid-β, into a broader conceptual framework of how AD arises, progresses, and may be effectively therapeutically targeted.-Nixon, R. A. Amyloid precursor protein and endosomal-lysosomal dysfunction in Alzheimer's disease: inseparable partners in a multifactorial disease. © FASEB.

  1. Proteases and proteolysis in Alzheimer disease: a multifactorial view on the disease process.

    Science.gov (United States)

    De Strooper, Bart

    2010-04-01

    Alzheimer disease is characterized by the accumulation of abnormally folded protein fragments, i.e., amyloid beta peptide (Abeta) and tau that precipitate in amyloid plaques and neuronal tangles, respectively. In this review we discuss the complicated proteolytic pathways that are responsible for the generation and clearance of these fragments, and how disturbances in these pathways interact and provide a background for a novel understanding of Alzheimer disease as a multifactorial disorder. Recent insights evolve from the static view that the morphologically defined plaques and tangles are disease driving towards a more dynamic, biochemical view in which the intermediary soluble Abeta oligomers and soluble tau fragments are considered as the main mediators of neurotoxicity. The relevance of proteolytic pathways, centered on the generation and clearance of toxic Abeta, on the cleavage and nucleation of tau, and on the general proteostasis of the neurons, then becomes obvious. Blocking or stimulating these pathways provide, or have the potential to provide, interesting drug targets, which raises the hope that we will be able to provide a cure for this dreadful disorder.

  2. The efficacy of a multifactorial memory training in older adults living in residential care settings.

    Science.gov (United States)

    Vranić, Andrea; Španić, Ana Marija; Carretti, Barbara; Borella, Erika

    2013-11-01

    Several studies have shown an increase in memory performance after teaching mnemonic techniques to older participants. However, transfer effects to non-trained tasks are generally either very small, or not found. The present study investigates the efficacy of a multifactorial memory training program for older adults living in a residential care center. The program combines teaching of memory strategies with activities based on metacognitive (metamemory) and motivational aspects. Specific training-related gains in the Immediate list recall task (criterion task), as well as transfer effects on measures of short-term memory, long-term memory, working memory, motivational (need for cognition), and metacognitive aspects (subjective measure of one's memory) were examined. Maintenance of training benefits was assessed after seven months. Fifty-one older adults living in a residential care center, with no cognitive impairments, participated in the study. Participants were randomly assigned to two programs: the experimental group attended the training program, while the active control group was involved in a program in which different psychological issues were discussed. A benefit in the criterion task and substantial general transfer effects were found for the trained group, but not for the active control, and they were maintained at the seven months follow-up. Our results suggest that training procedures, which combine teaching of strategies with metacognitive-motivational aspects, can improve cognitive functioning and attitude toward cognitive activities in older adults.

  3. Crossing the threshold

    Science.gov (United States)

    Bush, John; Tambasco, Lucas

    2017-11-01

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

  4. Heritability estimates derived from threshold analyses for ...

    African Journals Online (AJOL)

    Unknown

    reproductive traits in a composite multibreed beef cattle herd using a threshold model. A GFCAT set of ..... pressure for longevity include low heritabilities, the increased generation interval necessary to obtain survival information, and automatic selection because long-lived cows contribute more offspring to subsequent ...

  5. Low-threshold conical microcavity dye lasers

    DEFF Research Database (Denmark)

    Grossmann, Tobias; Schleede, Simone; Hauser, Mario

    2010-01-01

    element simulations confirm that lasing occurs in whispering gallery modes which corresponds well to the measured multimode laser-emission. The effect of dye concentration on lasing threshold and lasing wavelength is investigated and can be explained using a standard dye laser model....

  6. Diagnostic thresholds for ambulatory blood pressure moving lower: a review based on a meta-analysis-clinical implications

    DEFF Research Database (Denmark)

    Hansen, T.W.; Kikuya, M.; Thijs, L.

    2008-01-01

    Upper limits of normal ambulatory blood pressure (ABP) have been a matter of debate in recent years. Current diagnostic thresholds for ABP rely mainly on statistical parameters derived from reference populations. Recent findings from the International Database of Ambulatory Blood Pressure...... in Relation to Cardiovascular Outcome (IDACO) provide outcome-driven thresholds for ABP. Rounded systolic/diastolic thresholds for optimal ABP were found to be 115/75 mm Hg for 24 hours, 120/80 mm Hg for daytime, and 100/65 mm Hg for nighttime. The corresponding rounded thresholds for normal ABP were 125...... database is therefore being updated with additional population cohorts to enable the construction of multifactorial risk score charts, which also include ABP Udgivelsesdato: 2008/5...

  7. Albania - Thresholds I and II

    Data.gov (United States)

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

  8. Threshold switching uniformity in In2Se3 nanowire-based phase change memory

    International Nuclear Information System (INIS)

    Chen Jian; Du Gang; Liu Xiao-Yan

    2015-01-01

    The uniformity of threshold voltage and threshold current in the In 2 Se 3 nanowire-based phase change memory (PCM) devices is investigated. Based on the trap-limited transport model, amorphous layer thickness, trap density, and trap depth are considered to clarify their influences upon the threshold voltage and threshold current through simulations. (paper)

  9. Cost-effectiveness thresholds: pros and cons.

    Science.gov (United States)

    Bertram, Melanie Y; Lauer, Jeremy A; De Joncheere, Kees; Edejer, Tessa; Hutubessy, Raymond; Kieny, Marie-Paule; Hill, Suzanne R

    2016-12-01

    Cost-effectiveness analysis is used to compare the costs and outcomes of alternative policy options. Each resulting cost-effectiveness ratio represents the magnitude of additional health gained per additional unit of resources spent. Cost-effectiveness thresholds allow cost-effectiveness ratios that represent good or very good value for money to be identified. In 2001, the World Health Organization's Commission on Macroeconomics in Health suggested cost-effectiveness thresholds based on multiples of a country's per-capita gross domestic product (GDP). In some contexts, in choosing which health interventions to fund and which not to fund, these thresholds have been used as decision rules. However, experience with the use of such GDP-based thresholds in decision-making processes at country level shows them to lack country specificity and this - in addition to uncertainty in the modelled cost-effectiveness ratios - can lead to the wrong decision on how to spend health-care resources. Cost-effectiveness information should be used alongside other considerations - e.g. budget impact and feasibility considerations - in a transparent decision-making process, rather than in isolation based on a single threshold value. Although cost-effectiveness ratios are undoubtedly informative in assessing value for money, countries should be encouraged to develop a context-specific process for decision-making that is supported by legislation, has stakeholder buy-in, for example the involvement of civil society organizations and patient groups, and is transparent, consistent and fair.

  10. Threshold concepts in finance: student perspectives

    Science.gov (United States)

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

    2015-10-01

    Finance threshold concepts are the essential conceptual knowledge that underpin well-developed financial capabilities and are central to the mastery of finance. In this paper we investigate threshold concepts in finance from the point of view of students, by establishing the extent to which students are aware of threshold concepts identified by finance academics. In addition, we investigate the potential of a framework of different types of knowledge to differentiate the delivery of the finance curriculum and the role of modelling in finance. Our purpose is to identify ways to improve curriculum design and delivery, leading to better student outcomes. Whilst we find that there is significant overlap between what students identify as important in finance and the threshold concepts identified by academics, much of this overlap is expressed by indirect reference to the concepts. Further, whilst different types of knowledge are apparent in the student data, there is evidence that students do not necessarily distinguish conceptual from other types of knowledge. As well as investigating the finance curriculum, the research demonstrates the use of threshold concepts to compare and contrast student and academic perceptions of a discipline and, as such, is of interest to researchers in education and other disciplines.

  11. Cranial nerve threshold for thermal injury induced by MRI-guided high-intensity focused ultrasound (MRgHIFU): preliminary results on an optic nerve model.

    Science.gov (United States)

    Harnof, Sagi; Zibly, Zion; Cohen, Zvi; Shaw, Andrew; Schlaff, Cody; Kassel, Neal F

    2013-04-01

    Future clinical applications of magnetic resonance imaging-guided high-intensity focused ultrasound (MRgHIFU) are moving toward the management of different intracranial pathologies. We sought to validate the production, safety, and efficacy of thermal injury to cranial nerves generated by MRgHIFU. In this study, five female domestic pigs underwent a standard bifrontal craniectomy under general anesthesia. Treatment was then given using an MRgHIFU system to induce hyperthermic ablative sonication (6 to 10 s; 50 to 2000 J.) Histological analyses were done to confirm nerve damage; temperature measured on the optic nerve was approximately 53.4°C (range: 39°C to 70°C.) Histology demonstrated a clear definition between a necrotic, transitional zone, and normal tissue. MRgHIFU induces targeted thermal injury to nervous tissue within a specific threshold of 50°C to 60°C with the tissue near the sonication center yielding the greatest effect; adjacent tissue showed minimal changes. Additional studies utilizing this technology are required to further establish accurate threshold parameters for optic nerve thermo-ablation.

  12. A multifactorial analysis of obesity as CVD risk factor: Use of neural network based methods in a nutrigenetics context

    Directory of Open Access Journals (Sweden)

    Valavanis Ioannis K

    2010-09-01

    Full Text Available Abstract Background Obesity is a multifactorial trait, which comprises an independent risk factor for cardiovascular disease (CVD. The aim of the current work is to study the complex etiology beneath obesity and identify genetic variations and/or factors related to nutrition that contribute to its variability. To this end, a set of more than 2300 white subjects who participated in a nutrigenetics study was used. For each subject a total of 63 factors describing genetic variants related to CVD (24 in total, gender, and nutrition (38 in total, e.g. average daily intake in calories and cholesterol, were measured. Each subject was categorized according to body mass index (BMI as normal (BMI ≤ 25 or overweight (BMI > 25. Two artificial neural network (ANN based methods were designed and used towards the analysis of the available data. These corresponded to i a multi-layer feed-forward ANN combined with a parameter decreasing method (PDM-ANN, and ii a multi-layer feed-forward ANN trained by a hybrid method (GA-ANN which combines genetic algorithms and the popular back-propagation training algorithm. Results PDM-ANN and GA-ANN were comparatively assessed in terms of their ability to identify the most important factors among the initial 63 variables describing genetic variations, nutrition and gender, able to classify a subject into one of the BMI related classes: normal and overweight. The methods were designed and evaluated using appropriate training and testing sets provided by 3-fold Cross Validation (3-CV resampling. Classification accuracy, sensitivity, specificity and area under receiver operating characteristics curve were utilized to evaluate the resulted predictive ANN models. The most parsimonious set of factors was obtained by the GA-ANN method and included gender, six genetic variations and 18 nutrition-related variables. The corresponding predictive model was characterized by a mean accuracy equal of 61.46% in the 3-CV testing sets

  13. A multifactorial analysis of obesity as CVD risk factor: use of neural network based methods in a nutrigenetics context.

    Science.gov (United States)

    Valavanis, Ioannis K; Mougiakakou, Stavroula G; Grimaldi, Keith A; Nikita, Konstantina S

    2010-09-08

    Obesity is a multifactorial trait, which comprises an independent risk factor for cardiovascular disease (CVD). The aim of the current work is to study the complex etiology beneath obesity and identify genetic variations and/or factors related to nutrition that contribute to its variability. To this end, a set of more than 2300 white subjects who participated in a nutrigenetics study was used. For each subject a total of 63 factors describing genetic variants related to CVD (24 in total), gender, and nutrition (38 in total), e.g. average daily intake in calories and cholesterol, were measured. Each subject was categorized according to body mass index (BMI) as normal (BMI ≤ 25) or overweight (BMI > 25). Two artificial neural network (ANN) based methods were designed and used towards the analysis of the available data. These corresponded to i) a multi-layer feed-forward ANN combined with a parameter decreasing method (PDM-ANN), and ii) a multi-layer feed-forward ANN trained by a hybrid method (GA-ANN) which combines genetic algorithms and the popular back-propagation training algorithm. PDM-ANN and GA-ANN were comparatively assessed in terms of their ability to identify the most important factors among the initial 63 variables describing genetic variations, nutrition and gender, able to classify a subject into one of the BMI related classes: normal and overweight. The methods were designed and evaluated using appropriate training and testing sets provided by 3-fold Cross Validation (3-CV) resampling. Classification accuracy, sensitivity, specificity and area under receiver operating characteristics curve were utilized to evaluate the resulted predictive ANN models. The most parsimonious set of factors was obtained by the GA-ANN method and included gender, six genetic variations and 18 nutrition-related variables. The corresponding predictive model was characterized by a mean accuracy equal of 61.46% in the 3-CV testing sets. The ANN based methods revealed factors

  14. Uric acid as one of the important factors in multifactorial disorders – facts and controversies

    Science.gov (United States)

    Pasalic, Daria; Marinkovic, Natalija; Feher-Turkovic, Lana

    2012-01-01

    With considering serum concentration of the uric acid in humans we are observing hyperuricemia and possible gout development. Many epidemiological studies have shown the relationship between the uric acid and different disorders such are obesity, metabolic syndrome, hypertension and coronary artery disease. Clinicians and investigators recognized serum uric acid concentration as very important diagnostic and prognostic factor of many multifactorial disorders. This review presented few clinical conditions which are not directly related to uric acid, but the concentrations of uric acid might have a great impact in observing, monitoring, prognosis and therapy of such disorders. Uric acid is recognized as a marker of oxidative stress. Production of the uric acid includes enzyme xanthine oxidase which is involved in producing of radical-oxigen species (ROS). As by-products ROS have a significant role in the increased vascular oxidative stress and might be involved in atherogenesis. Uric acid may inhibit endothelial function by inhibition of nitric oxide-function under conditions of oxidative stress. Down regulation of nitric oxide and induction of endothelial dysfunction might also be involved in pathogenesis of hypertension. The most important and well evidenced is possible predictive role of uric acid in predicting short-term outcome (mortality) in acute myocardial infarction (AMI) patients and stroke. Nephrolithiasis of uric acid origin is significantly more common among patients with the metabolic syndrome and obesity. On contrary to this, uric acid also acts is an “antioxidant”, a free radical scavenger and a chelator of transitional metal ions which are converted to poorly reactive forms. PMID:22384520

  15. MLQ (Chestionarul Multifactorial de Leadership. Date preliminare pentru România

    Directory of Open Access Journals (Sweden)

    Dragoş Iliescu

    2008-01-01

    Full Text Available The Multifactorial Leadership Questionnaire (MLQ, in its latest version (5X, is a complex instrument, created in order to offer (1 a valid measurement of the transformational, transactional and passive components of leadership and also (2 as accurate a profile as possible for a person’s leadership potential and leadership-related behavior. The MLQ has been often used in laboratory and field researches, being an adequate, very useful tool for selection, transfer, promotion, development and counseling of individuals, groups or organizations. Various forms of the MLQ have been used in more than 30 countries, in industrial organizations, hospitals, religious institutions, military organizations, governmental agencies, universities, primary and secondary schools. It has been demonstrated that the efficiency of the MLQ remains constant, no matter if the leader is evaluated by his direct superiors, subordinates, co-workers or customers. An outstanding advantage of the MLQ is thus the possibility of 360° usage (with parallel forms of for selfevaluation and peer-evaluation. The adaptation of the MLQ started in Romania in 2005. This paper presents a pilot study on the self-evaluation form of the MLQ. A pilot sample of 229 participants was used, comprising mediumlevel and top managers, recruited from different corporations in Bucharest. Primary statistics, reliability, interscale correlations and the factor analysis of the MLQ are being presented and discussed, contrasted with the results reported by the original authors on USA samples. The results of these preliminary studies are encouraging, indicating that, in spite of an obvious need of extra research, the Romanian MLQ is an effective tool so far.

  16. Effectiveness of a multifactorial intervention to reduce physical restraints in nursing home residents.

    Science.gov (United States)

    Koczy, Petra; Becker, Clemens; Rapp, Kilian; Klie, Thomas; Beische, Denis; Büchele, Gisela; Kleiner, Andrea; Guerra, Virginia; Rissmann, Ulrich; Kurrle, Susan; Bredthauer, Doris

    2011-02-01

    To evaluate the effectiveness of a multifactorial intervention to reduce the use of physical restraints in residents of nursing homes. Cluster-randomized controlled trial. Forty-five nursing homes in Germany. Three hundred thirty-three residents who were being restrained at the start of the intervention. Persons responsible for the intervention in the nursing homes attended a 6-hour training course that included education about the reasons restraints are used, the adverse effects, and alternatives to their use. Technical aids, such as hip protectors and sensor mats, were provided. The training was designed to give the change agents tools for problem-solving to prevent behavioral symptoms and injuries from falls without using physical restraints. The main outcome was the complete cessation of physical restraint use on 3 consecutive days 3 months after the start of the intervention. Secondary outcomes were partial reductions in restraint use, percentage of fallers, number of psychoactive drugs, and occurrence of behavioral symptoms. The probability of being unrestrained in the intervention group (IG) was more than twice that in the control group (CG) at the end of the study (odds ratio=2.16, 95% confidence interval=1.05-4.46). A partial reduction of restraint use was also about twice as often achieved in the IG as in the CG. No negative effect was observed regarding medication or behavioral symptoms. The percentage of fallers was higher in the IG. The intervention reduced restraint use without a significant increase in falling, behavioral symptoms, or medication. © 2011, Copyright the Authors. Journal compilation © 2011, The American Geriatrics Society.

  17. Multifactorial determinants of target and novelty-evoked P300 amplitudes in children of addicted parents.

    Directory of Open Access Journals (Sweden)

    Anja S Euser

    Full Text Available BACKGROUND: Although P300 amplitude reductions constitute a persistent finding in children of addicted parents, relatively little is known about the specificity of this finding. The major aim of this study was to investigate the association between parental rearing, adverse life events, stress-reactivity, substance use and psychopathology on the one hand, and P300 amplitude in response to both target and novel distracter stimuli on the other hand. Moreover, we assessed whether risk group status (i.e., having a parental history of Substance Use Disorders [SUD] uniquely contributed to P300 amplitude variation above and beyond these other variables. METHODS: Event-related potentials were recorded in high-risk adolescents with a parental history of SUD (HR;n=80 and normal-risk controls (NR;n=100 while performing a visual Novelty Oddball paradigm. Stress-evoked cortisol levels were assessed and parenting, life adversities, substance use and psychopathology were examined by using self-reports. RESULTS: HR adolescents displayed smaller P300 amplitudes in response to novel- and to target stimuli than NR controls, while the latter only approached significance. Interestingly, the effect of having a parental history of SUD on target-P300 disappeared when all other variables were taken into account. Externalizing problem behavior was a powerful predictor of target-P300. In contrast, risk group status uniquely predicted novelty-P300 amplitude reductions above and beyond all other factors. CONCLUSION: Overall, the present findings suggest that the P300 amplitude reduction to novel stimuli might be a more specific endophenotype for SUD than the target-P300 amplitude. This pattern of results underscores the importance of conducting multifactorial assessments when examining important cognitive processes in at-risk adolescents.

  18. Threshold Concepts and Information Literacy

    Science.gov (United States)

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

    2011-01-01

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

  19. Multimodal distribution of human cold pain thresholds.

    Science.gov (United States)

    Lötsch, Jörn; Dimova, Violeta; Lieb, Isabel; Zimmermann, Michael; Oertel, Bruno G; Ultsch, Alfred

    2015-01-01

    It is assumed that different pain phenotypes are based on varying molecular pathomechanisms. Distinct ion channels seem to be associated with the perception of cold pain, in particular TRPM8 and TRPA1 have been highlighted previously. The present study analyzed the distribution of cold pain thresholds with focus at describing the multimodality based on the hypothesis that it reflects a contribution of distinct ion channels. Cold pain thresholds (CPT) were available from 329 healthy volunteers (aged 18 - 37 years; 159 men) enrolled in previous studies. The distribution of the pooled and log-transformed threshold data was described using a kernel density estimation (Pareto Density Estimation (PDE)) and subsequently, the log data was modeled as a mixture of Gaussian distributions using the expectation maximization (EM) algorithm to optimize the fit. CPTs were clearly multi-modally distributed. Fitting a Gaussian Mixture Model (GMM) to the log-transformed threshold data revealed that the best fit is obtained when applying a three-model distribution pattern. The modes of the identified three Gaussian distributions, retransformed from the log domain to the mean stimulation temperatures at which the subjects had indicated pain thresholds, were obtained at 23.7 °C, 13.2 °C and 1.5 °C for Gaussian #1, #2 and #3, respectively. The localization of the first and second Gaussians was interpreted as reflecting the contribution of two different cold sensors. From the calculated localization of the modes of the first two Gaussians, the hypothesis of an involvement of TRPM8, sensing temperatures from 25 - 24 °C, and TRPA1, sensing cold from 17 °C can be derived. In that case, subjects belonging to either Gaussian would possess a dominance of the one or the other receptor at the skin area where the cold stimuli had been applied. The findings therefore support a suitability of complex analytical approaches to detect mechanistically determined patterns from pain phenotype data.

  20. Towards a unifying basis of auditory thresholds: binaural summation.

    Science.gov (United States)

    Heil, Peter

    2014-04-01

    Absolute auditory threshold decreases with increasing sound duration, a phenomenon explainable by the assumptions that the sound evokes neural events whose probabilities of occurrence are proportional to the sound's amplitude raised to an exponent of about 3 and that a constant number of events are required for threshold (Heil and Neubauer, Proc Natl Acad Sci USA 100:6151-6156, 2003). Based on this probabilistic model and on the assumption of perfect binaural summation, an equation is derived here that provides an explicit expression of the binaural threshold as a function of the two monaural thresholds, irrespective of whether they are equal or unequal, and of the exponent in the model. For exponents >0, the predicted binaural advantage is largest when the two monaural thresholds are equal and decreases towards zero as the monaural threshold difference increases. This equation is tested and the exponent derived by comparing binaural thresholds with those predicted on the basis of the two monaural thresholds for different values of the exponent. The thresholds, measured in a large sample of human subjects with equal and unequal monaural thresholds and for stimuli with different temporal envelopes, are compatible only with an exponent close to 3. An exponent of 3 predicts a binaural advantage of 2 dB when the two ears are equally sensitive. Thus, listening with two (equally sensitive) ears rather than one has the same effect on absolute threshold as doubling duration. The data suggest that perfect binaural summation occurs at threshold and that peripheral neural signals are governed by an exponent close to 3. They might also shed new light on mechanisms underlying binaural summation of loudness.

  1. Prediction error variance and expected response to selection, when selection is based on the best predictor – for Gaussian and threshold characters, traits following a Poisson mixed model and survival traits

    Directory of Open Access Journals (Sweden)

    Jensen Just

    2002-05-01

    Full Text Available Abstract In this paper, we consider selection based on the best predictor of animal additive genetic values in Gaussian linear mixed models, threshold models, Poisson mixed models, and log normal frailty models for survival data (including models with time-dependent covariates with associated fixed or random effects. In the different models, expressions are given (when these can be found – otherwise unbiased estimates are given for prediction error variance, accuracy of selection and expected response to selection on the additive genetic scale and on the observed scale. The expressions given for non Gaussian traits are generalisations of the well-known formulas for Gaussian traits – and reflect, for Poisson mixed models and frailty models for survival data, the hierarchal structure of the models. In general the ratio of the additive genetic variance to the total variance in the Gaussian part of the model (heritability on the normally distributed level of the model or a generalised version of heritability plays a central role in these formulas.

  2. Europe's Other Poverty Measures: Absolute Thresholds Underlying Social Assistance

    Science.gov (United States)

    Bavier, Richard

    2009-01-01

    The first thing many learn about international poverty measurement is that European nations apply a "relative" poverty threshold and that they also do a better job of reducing poverty. Unlike the European model, the "absolute" U.S. poverty threshold does not increase in real value when the nation's standard of living rises,…

  3. A curve of thresholds governs plague epizootics in Central Asia

    DEFF Research Database (Denmark)

    Reijniers, Jonas; Davis, Stephen; Begon, Mike

    2012-01-01

    , it is common to assume a threshold defined by the ratio of vector and host abundances. Here, we show in contrast, both from field data and model simulations, that for plague (Yersinia pestis) in Kazakhstan, the invasion threshold quantity is based on the product of its host (Rhombomys opimus) and vector...

  4. Análise genética de escores de avaliação visual de bovinos com modelos bayesianos de limiar e linear Genetic analysis for visual scores of bovines with the linear and threshold bayesian models

    Directory of Open Access Journals (Sweden)

    Carina Ubirajara de Faria

    2008-07-01

    Full Text Available O objetivo deste trabalho foi comparar as estimativas de parâmetros genéticos obtidas em análises bayesianas uni-característica e bi-característica, em modelo animal linear e de limiar, considerando-se as características categóricas morfológicas de bovinos da raça Nelore. Os dados de musculosidade, estrutura física e conformação foram obtidos entre 2000 e 2005, em 3.864 animais de 13 fazendas participantes do Programa Nelore Brasil. Foram realizadas análises bayesianas uni e bi-características, em modelos de limiar e linear. De modo geral, os modelos de limiar e linear foram eficientes na estimação dos parâmetros genéticos para escores visuais em análises bayesianas uni-características. Nas análises bi-características, observou-se que: com utilização de dados contínuos e categóricos, o modelo de limiar proporcionou estimativas de correlação genética de maior magnitude do que aquelas do modelo linear; e com o uso de dados categóricos, as estimativas de herdabilidade foram semelhantes. A vantagem do modelo linear foi o menor tempo gasto no processamento das análises. Na avaliação genética de animais para escores visuais, o uso do modelo de limiar ou linear não influenciou a classificação dos animais, quanto aos valores genéticos preditos, o que indica que ambos os modelos podem ser utilizados em programas de melhoramento genético.The objective of this work was to compare the estimates of genetic parameters obtained in single-trait and two-trait bayesian analyses, under linear and threshold animal models, considering categorical morphological traits of bovines of the Nelore breed. Data of musculature, physical structure and conformation were obtained between years 2000 and 2005, from 3,864 bovines of the Nelore breed from 13 participant farms of the Nelore Brazil Program. Single-trait and two-trait bayesian analyses were performed under linear and threshold animal models. In general, the linear and threshold

  5. Hip fracture prevention with a multifactorial educational program in elderly community-dwelling Finnish women.

    Science.gov (United States)

    Pekkarinen, T; Löyttyniemi, E; Välimäki, M

    2013-12-01

    Guidelines suggest identification of women at fracture risk by bone density measurement and subsequently pharmacotherapy. However, most women who sustain a hip fracture do not have osteoporosis in terms of bone density. The present non-pharmacological intervention among elderly women unselected for osteoporosis reduced hip fracture risk by 55 % providing an alternative approach to fracture prevention. Hip fractures are expensive for society and cause disability for those who sustain them. We studied whether a multifactorial non-pharmacological prevention program reduces hip fracture risk in elderly women. A controlled trial concerning 60- to 70-year-old community-dwelling Finnish women was undertaken. A random sample was drawn from the Population Information System and assigned into the intervention group (IG) and control group (CG). Of the 2,547 women who were invited to the IG, 1,004 (39 %) and of the 2,120 invited to the CG, 1,174 (55 %) participated. The IG participated in a fracture prevention program for 1 week at a rehabilitation center followed by review days twice. The CG received no intervention. During the 10-year follow-up, both groups participated in survey questionnaire by mail. Outcome of interest was occurrence of hip fractures and changes in bone-health-related lifestyle. During the follow-up, 12 (1.2 %) women in the IG and 29 (2.5 %) in the CG sustained a hip fracture (P = 0.039). The determinants of hip fractures by stepwise logistic regression were baseline smoking (odds ratio (OR) 4.32 (95 % confidence interval [CI] 2.14-8.71), age OR 1.15/year (95 % CI 1.03-1.28), fall history OR 2.7 (95 % CI 1.24-5.9), stroke history OR 2.99 (95 % CI 1.19-7.54) and participating in this program OR 0.45 (95 % CI 0.22-0.93). Starting vitamin D and calcium supplement use was more common in the IG compared with the CG. The results suggest that this non-pharmacological fracture prevention program may reduce the risk of hip fractures in elderly

  6. Do non-targeted effects increase or decrease low dose risk in relation to the linear-non-threshold (LNT) model?

    International Nuclear Information System (INIS)

    Little, M.P.

    2010-01-01

    In this paper we review the evidence for departure from linearity for malignant and non-malignant disease and in the light of this assess likely mechanisms, and in particular the potential role for non-targeted effects. Excess cancer risks observed in the Japanese atomic bomb survivors and in many medically and occupationally exposed groups exposed at low or moderate doses are generally statistically compatible. For most cancer sites the dose-response in these groups is compatible with linearity over the range observed. The available data on biological mechanisms do not provide general support for the idea of a low dose threshold or hormesis. This large body of evidence does not suggest, indeed is not statistically compatible with, any very large threshold in dose for cancer, or with possible hormetic effects, and there is little evidence of the sorts of non-linearity in response implied by non-DNA-targeted effects. There are also excess risks of various types of non-malignant disease in the Japanese atomic bomb survivors and in other groups. In particular, elevated risks of cardiovascular disease, respiratory disease and digestive disease are observed in the A-bomb data. In contrast with cancer, there is much less consistency in the patterns of risk between the various exposed groups; for example, radiation-associated respiratory and digestive diseases have not been seen in these other (non-A-bomb) groups. Cardiovascular risks have been seen in many exposed populations, particularly in medically exposed groups, but in contrast with cancer there is much less consistency in risk between studies: risks per unit dose in epidemiological studies vary over at least two orders of magnitude, possibly a result of confounding and effect modification by well known (but unobserved) risk factors. In the absence of a convincing mechanistic explanation of epidemiological evidence that is, at present, less than persuasive, a cause-and-effect interpretation of the reported

  7. Music effect on pain threshold evaluated with current perception threshold

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    AIM: Music relieves anxiety and psychotic tension. This effect of music is applied to surgical operation in the hospital and dental office. It is still unclear whether this music effect is only limited to the psychological aspect but not to the physical aspect or whether its music effect is influenced by the mood or emotion of audience. To elucidate these issues, we evaluated the music effect on pain threshold by current perception threshold (CPT) and profile of mood states (POMC) test. METHODS: Healthy 30 subjects (12 men, 18 women, 25-49 years old, mean age 34.9) were tested. (1)After POMC test, all subjects were evaluated pain threshold with CPT by Neurometer (Radionics, USA) under 6 conditions, silence, listening to the slow tempo classic music, nursery music, hard rock music, classic paino music and relaxation music with 30 seconds interval. (2)After Stroop color word test as the stresser, pain threshold was evaluated with CPT under 2 conditions, silence and listening to the slow tempo classic music. RESULTS: Under litening to the music, CPT sores increased, especially 2 000 Hz level related with compression, warm and pain sensation. Type of music, preference of music and stress also affected CPT score. CONCLUSION: The present study demonstrated that the concentration on the music raise the pain threshold and that stress and mood influence the music effect on pain threshold.

  8. Two-stage unified stretched-exponential model for time-dependence of threshold voltage shift under positive-bias-stresses in amorphous indium-gallium-zinc oxide thin-film transistors

    Science.gov (United States)

    Jeong, Chan-Yong; Kim, Hee-Joong; Hong, Sae-Young; Song, Sang-Hun; Kwon, Hyuck-In

    2017-08-01

    In this study, we show that the two-stage unified stretched-exponential model can more exactly describe the time-dependence of threshold voltage shift (ΔV TH) under long-term positive-bias-stresses compared to the traditional stretched-exponential model in amorphous indium-gallium-zinc oxide (a-IGZO) thin-film transistors (TFTs). ΔV TH is mainly dominated by electron trapping at short stress times, and the contribution of trap state generation becomes significant with an increase in the stress time. The two-stage unified stretched-exponential model can provide useful information not only for evaluating the long-term electrical stability and lifetime of the a-IGZO TFT but also for understanding the stress-induced degradation mechanism in a-IGZO TFTs.

  9. Two-locus maximum lod score analysis of a multifactorial trait: joint consideration of IDDM2 and IDDM4 with IDDM1 in type 1 diabetes.

    Science.gov (United States)

    Cordell, H J; Todd, J A; Bennett, S T; Kawaguchi, Y; Farrall, M

    1995-10-01

    To investigate the genetic component of multifactorial diseases such as type 1 (insulin-dependent) diabetes mellitus (IDDM), models involving the joint action of several disease loci are important. These models can give increased power to detect an effect and a greater understanding of etiological mechanisms. Here, we present an extension of the maximum lod score method of N. Risch, which allows the simultaneous detection and modeling of two unlinked disease loci. Genetic constraints on the identical-by-descent sharing probabilities, analogous to the "triangle" restrictions in the single-locus method, are derived, and the size and power of the test statistics are investigated. The method is applied to affected-sib-pair data, and the joint effects of IDDM1 (HLA) and IDDM2 (the INS VNTR) and of IDDM1 and IDDM4 (FGF3-linked) are assessed with relation to the development of IDDM. In the presence of genetic heterogeneity, there is seen to be a significant advantage in analyzing more than one locus simultaneously. Analysis of these families indicates that the effects at IDDM1 and IDDM2 are well described by a multiplicative genetic model, while those at IDDM1 and IDDM4 follow a heterogeneity model.

  10. Two-locus maximum lod score analysis of a multifactorial trait: Joint consideration of IDDM2 and IDDM4 with IDDMI in type 1 diabetes

    Energy Technology Data Exchange (ETDEWEB)

    Cordell, H.J.; Todd, J.A.; Bennett, S.T. [Univ. of Oxford (United Kingdom)] [and others

    1995-10-01

    To investigate the genetic component of multifactorial diseases such as type 1 (insulin-dependent) diabetes mellitus (IDDM), models involving the joint action of several disease loci are important. These models can give increased power to detect an effect and a greater understanding of etiological mechanisms. Here, we present an extension of the maximum lod score method of N. Risch, which allows the simultaneous detection and modeling of two unlinked disease loci. Genetic constraints on the identical-by-descent sharing probabilities, analogous to the {open_quotes}triangle{close_quotes} restrictions in the single-locus method, are derived, and the size and power of the test statistics are investigated. The method is applied to affected-sib-pair data, and the joint effects of IDDM1 (HLA) and IDDM2 (the INS VNTR) and of IDDM1 and IDDM4 (FGF3-linked) are assessed with relation to the development of IDDM. In the presence of genetic heterogeneity, there is seen to be a significant advantage in analyzing more than one locus simultaneously. Analysis of these families indicates that the effects at IDDM1 and IDDM2 are well described by a multiplicative genetic model, while those at IDDM1 and IDDM4 follow a heterogeneity model. 17 refs., 9 tabs.

  11. Analysis of linear measurements on 3D surface models using CBCT data segmentation obtained by automatic standard pre-set thresholds in two segmentation software programs: an in vitro study.

    Science.gov (United States)

    Poleti, Marcelo Lupion; Fernandes, Thais Maria Freire; Pagin, Otávio; Moretti, Marcela Rodrigues; Rubira-Bullen, Izabel Regina Fischer

    2016-01-01

    The aim of this in vitro study was to evaluate the reliability and accuracy of linear measurements on three-dimensional (3D) surface models obtained by standard pre-set thresholds in two segmentation software programs. Ten mandibles with 17 silica markers were scanned for 0.3-mm voxels in the i-CAT Classic (Imaging Sciences International, Hatfield, PA, USA). Twenty linear measurements were carried out by two observers two times on the 3D surface models: the Dolphin Imaging 11.5 (Dolphin Imaging & Management Solutions, Chatsworth, CA, USA), using two filters(Translucent and Solid-1), and in the InVesalius 3.0.0 (Centre for Information Technology Renato Archer, Campinas, SP, Brazil). The physical measurements were made by another observer two times using a digital caliper on the dry mandibles. Excellent intra- and inter-observer reliability for the markers, physical measurements, and 3D surface models were found (intra-class correlation coefficient (ICC) and Pearson's r ≥ 0.91). The linear measurements on 3D surface models by Dolphin and InVesalius software programs were accurate (Dolphin Solid-1 > InVesalius > Dolphin Translucent). The highest absolute and percentage errors were obtained for the variable R1-R1 (1.37 mm) and MF-AC (2.53 %) in the Dolphin Translucent and InVesalius software, respectively. Linear measurements on 3D surface models obtained by standard pre-set thresholds in the Dolphin and InVesalius software programs are reliable and accurate compared with physical measurements. Studies that evaluate the reliability and accuracy of the 3D models are necessary to ensure error predictability and to establish diagnosis, treatment plan, and prognosis in a more realistic way.

  12. A non-parametric framework for estimating threshold limit values

    Directory of Open Access Journals (Sweden)

    Ulm Kurt

    2005-11-01

    Full Text Available Abstract Background To estimate a threshold limit value for a compound known to have harmful health effects, an 'elbow' threshold model is usually applied. We are interested on non-parametric flexible alternatives. Methods We describe how a step function model fitted by isotonic regression can be used to estimate threshold limit values. This method returns a set of candidate locations, and we discuss two algorithms to select the threshold among them: the reduced isotonic regression and an algorithm considering the closed family of hypotheses. We assess the performance of these two alternative approaches under different scenarios in a simulation study. We illustrate the framework by analysing the data from a study conducted by the German Research Foundation aiming to set a threshold limit value in the exposure to total dust at workplace, as a causal agent for developing chronic bronchitis. Results In the paper we demonstrate the use and the properties of the proposed methodology along with the results from an application. The method appears to detect the threshold with satisfactory success. However, its performance can be compromised by the low power to reject the constant risk assumption when the true dose-response relationship is weak. Conclusion The estimation of thresholds based on isotonic framework is conceptually simple and sufficiently powerful. Given that in threshold value estimation context there is not a gold standard method, the proposed model provides a useful non-parametric alternative to the standard approaches and can corroborate or challenge their findings.

  13. Parton distributions with threshold resummation

    CERN Document Server

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

    2015-01-01

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

  14. Conceptions of nuclear threshold status

    International Nuclear Information System (INIS)

    Quester, G.H.

    1991-01-01

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

  15. Rayleigh scattering from ions near threshold

    International Nuclear Information System (INIS)

    Roy, S.C.; Gupta, S.K.S.; Kissel, L.; Pratt, R.H.

    1988-01-01

    Theoretical studies of Rayleigh scattering of photons from neon atoms with different degrees of ionization, for energies both below and above the K-edges of the ions, are presented. Some unexpected structures both in Rayleigh scattering and in photoionization from neutral and weakly ionized atoms, very close to threshold, have been reported. It has recently been realized that some of the predicted structures may have a nonphysical origin and are due to the limitation of the independent-particle model and also to the use of a Coulombic Latter tail. Use of a K-shell vacancy potential - in which an electron is assumed to be removed from the K-shell - in calculating K-shell Rayleigh scattering amplitudes removes some of the structure effects near threshold. We present in this work a discussion of scattering angular distributions and total cross sections, obtained utilizing vacancy potentials, and compare these predictions with those previously obtained in other potential model. (author) [pt

  16. Alveolar bone-loss area localization in periodontitis radiographs based on threshold segmentation with a hybrid feature fused of intensity and the H-value of fractional Brownian motion model.

    Science.gov (United States)

    Lin, P L; Huang, P W; Huang, P Y; Hsu, H C

    2015-10-01

    Periodontitis involves progressive loss of alveolar bone around the teeth. Hence, automatic alveolar bone-loss (ABL) measurement in periapical radiographs can assist dentists in diagnosing such disease. In this paper, we propose an effective method for ABL area localization and denote it as ABLIfBm. ABLIfBm is a threshold segmentation method that uses a hybrid feature fused of both intensity and texture measured by the H-value of fractional Brownian motion (fBm) model, where the H-value is the Hurst coefficient in the expectation function of a fBm curve (intensity change) and is directly related to the value of fractal dimension. Adopting leave-one-out cross validation training and testing mechanism, ABLIfBm trains weights for both features using Bayesian classifier and transforms the radiograph image into a feature image obtained from a weighted average of both features. Finally, by Otsu's thresholding, it segments the feature image into normal and bone-loss regions. Experimental results on 31 periodontitis radiograph images in terms of mean true positive fraction and false positive fraction are about 92.5% and 14.0%, respectively, where the ground truth is provided by a dentist. The results also demonstrate that ABLIfBm outperforms (a) the threshold segmentation method using either feature alone or a weighted average of the same two features but with weights trained differently; (b) a level set segmentation method presented earlier in literature; and (c) segmentation methods based on Bayesian, K-NN, or SVM classifier using the same two features. Our results suggest that the proposed method can effectively localize alveolar bone-loss areas in periodontitis radiograph images and hence would be useful for dentists in evaluating degree of bone-loss for periodontitis patients. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  17. THE ROLE OF MULTIFACTORIAL APPROACH TO TREATMENT OF OBESITY IN FEMALES

    Directory of Open Access Journals (Sweden)

    O. L. Andrianova

    2015-01-01

    Full Text Available Background: Obesity is characterized by an increased risk of diabetes mellitus, coronary heart disease, arterial hypertension and reproductive system disorders, which makes it necessary to implement multifactorial correction of metabolic disturbances.Aim: To analyze diet intake structure of patients with obesity, efficacy and safety of sibutramine monotherapy and sibutramine/metformin combination therapy in the formation of adequate nutritional stereotypes and reduction of bodyweight.Materials and methods: Eighty-two obese women aged 18 to 49 years (mean age 29.7±5.7 years were included into this observational study. Inclusion criteria: women aged 18 to 49 years, with waist circumference>80 cm, body mass index (BMI>27 kg/m², triglyceride level>1.7  mmol/L and/or low-density lipoprotein cholesterol>3.8  mmol/L, and/or high-density lipoprotein cholesterol<1.29 mmol/L. Exclusion criteria in this study were presence of severe somatic and endocrine disorders. The control group consisted of 35 healthy women aged 18 to 49 years (mean age 28.7±5.6 years. All patients were recruited within the observational program PrimaVera. Results: Analysis of dietary intake in female obese patients showed an excess of daily energy intake of 650±250 kcal compared to that in subjects with normal BMI and normal waist circumference. Seventy one percent of patients had excessive expectations from treatment duration and desired weight loss. For control of their eating behavior, 52 patients were administered Reduxin® (sibutramine+cellulose microcristallic 10 mg daily. Other 30 patients (24 women with a history of carbohydrate metabolism disturbances during pregnancy and 6 women who had delivered babies with birth weight of above4 kg were administered Reduxin® 10 mg and metformin 500  mg daily, with weekly dose increase by 500  mg to the final dose of 1500 mg daily. The treatment lasted for 24  weeks. Daily caloric intake decreased by 24±4% from baseline (p<0

  18. Cost–effectiveness thresholds: pros and cons

    Science.gov (United States)

    Lauer, Jeremy A; De Joncheere, Kees; Edejer, Tessa; Hutubessy, Raymond; Kieny, Marie-Paule; Hill, Suzanne R

    2016-01-01

    Abstract Cost–effectiveness analysis is used to compare the costs and outcomes of alternative policy options. Each resulting cost–effectiveness ratio represents the magnitude of additional health gained per additional unit of resources spent. Cost–effectiveness thresholds allow cost–effectiveness ratios that represent good or very good value for money to be identified. In 2001, the World Health Organization’s Commission on Macroeconomics in Health suggested cost–effectiveness thresholds based on multiples of a country’s per-capita gross domestic product (GDP). In some contexts, in choosing which health interventions to fund and which not to fund, these thresholds have been used as decision rules. However, experience with the use of such GDP-based thresholds in decision-making processes at country level shows them to lack country specificity and this – in addition to uncertainty in the modelled cost–effectiveness ratios – can lead to the wrong decision on how to spend health-care resources. Cost–effectiveness information should be used alongside other considerations – e.g. budget impact and feasibility considerations – in a transparent decision-making process, rather than in isolation based on a single threshold value. Although cost–effectiveness ratios are undoubtedly informative in assessing value for money, countries should be encouraged to develop a context-specific process for decision-making that is supported by legislation, has stakeholder buy-in, for example the involvement of civil society organizations and patient groups, and is transparent, consistent and fair. PMID:27994285

  19. Identifying thresholds for ecosystem-based management.

    Directory of Open Access Journals (Sweden)

    Jameal F Samhouri

    Full Text Available BACKGROUND: One of the greatest obstacles to moving ecosystem-based management (EBM from concept to practice is the lack of a systematic approach to defining ecosystem-level decision criteria, or reference points that trigger management action. METHODOLOGY/PRINCIPAL FINDINGS: To assist resource managers and policymakers in developing EBM decision criteria, we introduce a quantitative, transferable method for identifying utility thresholds. A utility threshold is the level of human-induced pressure (e.g., pollution at which small changes produce substantial improvements toward the EBM goal of protecting an ecosystem's structural (e.g., diversity and functional (e.g., resilience attributes. The analytical approach is based on the detection of nonlinearities in relationships between ecosystem attributes and pressures. We illustrate the method with a hypothetical case study of (1 fishing and (2 nearshore habitat pressure using an empirically-validated marine ecosystem model for British Columbia, Canada, and derive numerical threshold values in terms of the density of two empirically-tractable indicator groups, sablefish and jellyfish. We also describe how to incorporate uncertainty into the estimation of utility thresholds and highlight their value in the context of understanding EBM trade-offs. CONCLUSIONS/SIGNIFICANCE: For any policy scenario, an understanding of utility thresholds provides insight into the amount and type of management intervention required to make significant progress toward improved ecosystem structure and function. The approach outlined in this paper can be applied in the context of single or multiple human-induced pressures, to any marine, freshwater, or terrestrial ecosystem, and should facilitate more effective management.

  20. Glint Field Trial Results and Application to Glint Threshold Distance Algorithm

    National Research Council Canada - National Science Library

    Chevalier, William

    1998-01-01

    .... Glint threshold algorithm. Software adjustments would tentatively be made to the existing algorithm to improve glint threshold distance calculation accuracy, making the modified model a better iterative eye armor design tool...

  1. Effects of a multifactorial falls prevention program for people with stroke returning home after rehabilitation: a randomized controlled trial.

    Science.gov (United States)

    Batchelor, Frances A; Hill, Keith D; Mackintosh, Shylie F; Said, Catherine M; Whitehead, Craig H

    2012-09-01

    To determine whether a multifactorial falls prevention program reduces falls in people with stroke at risk of recurrent falls and whether this program leads to improvements in gait, balance, strength, and fall-related efficacy. A single blind, multicenter, randomized controlled trial with 12-month follow-up. Participants were recruited after discharge from rehabilitation and followed up in the community. Participants (N=156) were people with stroke at risk of recurrent falls being discharged home from rehabilitation. Tailored multifactorial falls prevention program and usual care (n=71) or control (usual care, n=85). Primary outcomes were rate of falls and proportion of fallers. Secondary outcomes included injurious falls, falls risk, participation, activity, leg strength, gait speed, balance, and falls efficacy. There was no significant difference in fall rate (intervention: 1.89 falls/person-year, control: 1.76 falls/person-year, incidence rate ratio=1.10, P=.74) or the proportion of fallers between the groups (risk ratio=.83, 95% confidence interval=.60-1.14). There was no significant difference in injurious fall rate (intervention: .74 injurious falls/person-year, control: .49 injurious falls/person-year, incidence rate ratio=1.57, P=.25), and there were no significant differences between groups on any other secondary outcome. This multifactorial falls prevention program was not effective in reducing falls in people with stroke who are at risk of falls nor was it more effective than usual care in improving gait, balance, and strength in people with stroke. Further research is required to identify effective interventions for this high-risk group. Copyright © 2012 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

  2. On setting NRC alarm thresholds for inventory differences and process unit loss estimators: Clarifying their statistical basis with hypothesis testing methods and error propagation models from Jaech, Bowen and Bennett and IAEA

    International Nuclear Information System (INIS)

    Ong, L.

    1995-01-01

    Major fuel cycle facilities in the US private sector are required to respond-at predetermined alarm levels-to various special nuclear material loss estimators in the material control and accounting (MC and A) area. This paper presents US Nuclear Regulatory Commission (NRC) policy, along with the underlying statistical rationale, for establishing and inspecting the application of thresholds to detect excessive inventory differences (ID). Accordingly, escalating responsive action must be taken to satisfy NRC's MC and A regulations for low-enriched uranium (LEU) fuel conversion/fabrication plants and LEU enrichment facilities. The establishment of appropriate ID detection thresholds depends on a site-specific goal quantity, a specified probability of detection and the standard error of the ID. Regulatory guidelines for ID significance tests and process control tests conducted by licensees with highly enriched uranium are similarly rationalized in definitive hypothesis testing including null and alternative hypotheses; statistical efforts of the first, second, third, and fourth kinds; and suitable test statistics, uncertainty estimates, prevailing assumptions, and critical values for comparisons. Conceptual approaches are described in the context of significance test considerations and measurement error models including the treatment of so called ''systematic error variance'' effects as observations of random variables in the statistical sense

  3. Small-threshold behaviour of two-loop self-energy diagrams: two-particle thresholds

    International Nuclear Information System (INIS)

    Berends, F.A.; Davydychev, A.I.; Moskovskij Gosudarstvennyj Univ., Moscow; Smirnov, V.A.; Moskovskij Gosudarstvennyj Univ., Moscow

    1996-01-01

    The behaviour of two-loop two-point diagrams at non-zero thresholds corresponding to two-particle cuts is analyzed. The masses involved in a cut and the external momentum are assumed to be small as compared to some of the other masses of the diagram. By employing general formulae of asymptotic expansions of Feynman diagrams in momenta and masses, we construct an algorithm to derive analytic approximations to the diagrams. In such a way, we calculate several first coefficients of the expansion. Since no conditions on relative values of the small masses and the external momentum are imposed, the threshold irregularities are described analytically. Numerical examples, using diagrams occurring in the standard model, illustrate the convergence of the expansion below the first large threshold. (orig.)

  4. A critical experimental study of the classical tactile threshold theory

    Directory of Open Access Journals (Sweden)

    Medina Leonel E

    2010-06-01

    Full Text Available Abstract Background The tactile sense is being used in a variety of applications involving tactile human-machine interfaces. In a significant number of publications the classical threshold concept plays a central role in modelling and explaining psychophysical experimental results such as in stochastic resonance (SR phenomena. In SR, noise enhances detection of sub-threshold stimuli and the phenomenon is explained stating that the required amplitude to exceed the sensory threshold barrier can be reached by adding noise to a sub-threshold stimulus. We designed an experiment to test the validity of the classical vibrotactile threshold. Using a second choice experiment, we show that individuals can order sensorial events below the level known as the classical threshold. If the observer's sensorial system is not activated by stimuli below the threshold, then a second choice could not be above the chance level. Nevertheless, our experimental results are above that chance level contradicting the definition of the classical tactile threshold. Results We performed a three alternative forced choice detection experiment on 6 subjects asking them first and second choices. In each trial, only one of the intervals contained a stimulus and the others contained only noise. According to the classical threshold assumptions, a correct second choice response corresponds to a guess attempt with a statistical frequency of 50%. Results show an average of 67.35% (STD = 1.41% for the second choice response that is not explained by the classical threshold definition. Additionally, for low stimulus amplitudes, second choice correct detection is above chance level for any detectability level. Conclusions Using a second choice experiment, we show that individuals can order sensorial events below the level known as a classical threshold. If the observer's sensorial system is not activated by stimuli below the threshold, then a second choice could not be above the chance

  5. Wafer plane inspection with soft resist thresholding

    Science.gov (United States)

    Hess, Carl; Shi, Rui-fang; Wihl, Mark; Xiong, Yalin; Pang, Song

    2008-10-01

    Wafer Plane Inspection (WPI) is an inspection mode on the KLA-Tencor TeraScaTM platform that uses the high signalto- noise ratio images from the high numerical aperture microscope, and then models the entire lithographic process to enable defect detection on the wafer plane[1]. This technology meets the needs of some advanced mask manufacturers to identify the lithographically-significant defects while ignoring the other non-lithographically-significant defects. WPI accomplishes this goal by performing defect detection based on a modeled image of how the mask features would actually print in the photoresist. There are several advantages to this approach: (1) the high fidelity of the images provide a sensitivity advantage over competing approaches; (2) the ability to perform defect detection on the wafer plane allows one to only see those defects that have a printing impact on the wafer; (3) the use of modeling on the lithographic portion of the flow enables unprecedented flexibility to support arbitrary illumination profiles, process-window inspection in unit time, and combination modes to find both printing and non-printing defects. WPI is proving to be a valuable addition to the KLA-Tencor detection algorithm suite. The modeling portion of WPI uses a single resist threshold as the final step in the processing. This has been shown to be adequate on several advanced customer layers, but is not ideal for all layers. Actual resist chemistry has complicated processes including acid and base-diffusion and quench that are not consistently well-modeled with a single resist threshold. We have considered the use of an advanced resist model for WPI, but rejected it because the burdensome requirements for the calibration of the model were not practical for reticle inspection. This paper describes an alternative approach that allows for a "soft" resist threshold to be applied that provides a more robust solution for the most challenging processes. This approach is just

  6. Ultracompact low-threshold organic laser.

    Science.gov (United States)

    Deotare, Parag B; Mahony, Thomas S; Bulović, Vladimir

    2014-11-25

    We report an ultracompact low-threshold laser with an Alq3:DCM host:guest molecular organic thin film gain layer. The device uses a photonic crystal nanobeam cavity which provides a high quality factor to mode volume (Q/V) ratio and increased spontaneous emission factor along with a small footprint. Lasing is observed with a threshold of 4.2 μJ/cm(2) when pumped by femtosecond pulses of λ = 400 nm wavelength light. We also model the dynamics of the laser and show good agreement with the experimental data. The inherent waveguide geometry of the structure enables easy on-chip integration with potential applications in biochemical sensing, inertial sensors, and data communication.

  7. Doubler system quench detection threshold

    International Nuclear Information System (INIS)

    Kuepke, K.; Kuchnir, M.; Martin, P.

    1983-01-01

    The experimental study leading to the determination of the sensitivity needed for protecting the Fermilab Doubler from damage during quenches is presented. The quench voltage thresholds involved were obtained from measurements made on Doubler cable of resistance x temperature and voltage x time during quenches under several currents and from data collected during operation of the Doubler Quench Protection System as implemented in the B-12 string of 20 magnets. At 4kA, a quench voltage threshold in excess of 5.OV will limit the peak Doubler cable temperature to 452K for quenches originating in the magnet coils whereas a threshold of 0.5V is required for quenches originating outside of coils

  8. Thermotactile perception thresholds measurement conditions.

    Science.gov (United States)

    Maeda, Setsuo; Sakakibara, Hisataka

    2002-10-01

    The purpose of this paper is to investigate the effects of posture, push force and rate of temperature change on thermotactile thresholds and to clarify suitable measuring conditions for Japanese people. Thermotactile (warm and cold) thresholds on the right middle finger were measured with an HVLab thermal aesthesiometer. Subjects were eight healthy male Japanese students. The effects of posture in measurement were examined in the posture of a straight hand and forearm placed on a support, the same posture without a support, and the fingers and hand flexed at the wrist with the elbow placed on a desk. The finger push force applied to the applicator of the thermal aesthesiometer was controlled at a 0.5, 1.0, 2.0 and 3.0 N. The applicator temperature was changed to 0.5, 1.0, 1.5, 2.0 and 2.5 degrees C/s. After each measurement, subjects were asked about comfort under the measuring conditions. Three series of experiments were conducted on different days to evaluate repeatability. Repeated measures ANOVA showed that warm thresholds were affected by the push force and the rate of temperature change and that cold thresholds were influenced by posture and push force. The comfort assessment indicated that the measurement posture of a straight hand and forearm laid on a support was the most comfortable for the subjects. Relatively high repeatability was obtained under measurement conditions of a 1 degrees C/s temperature change rate and a 0.5 N push force. Measurement posture, push force and rate of temperature change can affect the thermal threshold. Judging from the repeatability, a push force of 0.5 N and a temperature change of 1.0 degrees C/s in the posture with the straight hand and forearm laid on a support are recommended for warm and cold threshold measurements.

  9. Prediction of long-term absence due to sickness in employees: development and validation of a multifactorial risk score in two cohort studies.

    Science.gov (United States)

    Airaksinen, Jaakko; Jokela, Markus; Virtanen, Marianna; Oksanen, Tuula; Koskenvuo, Markku; Pentti, Jaana; Vahtera, Jussi; Kivimäki, Mika

    2018-01-24

    Objectives This study aimed to develop and validate a risk prediction model for long-term sickness absence. Methods Survey responses on work- and lifestyle-related questions from 65 775 public-sector employees were linked to sickness absence records to develop a prediction score for medically-certified sickness absence lasting >9 days and ≥90 days. The score was externally validated using data from an independent population-based cohort of 13 527 employees. For both sickness absence outcomes, a full model including 46 candidate predictors was reduced to a parsimonious model using least-absolute-shrinkage-and-selection-operator (LASSO) regression. Predictive performance of the model was evaluated using C-index and calibration plots. Results Variance explained in ≥90-day sickness absence by the full model was 12.5%. In the parsimonious model, the predictors included self-rated health (linear and quadratic term), depression, sex, age (linear and quadratic), socioeconomic position, previous sickness absences, number of chronic diseases, smoking, shift work, working night shift, and quadratic terms for body mass index and Jenkins sleep scale. The discriminative ability of the score was good (C-index 0.74 in internal and 0.73 in external validation). Calibration plots confirmed high correspondence between the predicted and observed risk. In >9-day sickness absence, the full model explained 15.2% of the variance explained, but the C-index of the parsimonious model was poor (<0.65). Conclusions Individuals' risk of a long-term sickness absence that lasts ≥90 days can be estimated using a brief risk score. The predictive performance of this score is comparable to those for established multifactorial risk algorithms for cardiovascular disease, such as the Framingham risk score.

  10. Factors affecting mechanical (nociceptive) thresholds in piglets.

    Science.gov (United States)

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

    2012-11-01

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

  11. Optimization Problems on Threshold Graphs

    Directory of Open Access Journals (Sweden)

    Elena Nechita

    2010-06-01

    Full Text Available During the last three decades, different types of decompositions have been processed in the field of graph theory. Among these we mention: decompositions based on the additivity of some characteristics of the graph, decompositions where the adjacency law between the subsets of the partition is known, decompositions where the subgraph induced by every subset of the partition must have predeterminate properties, as well as combinations of such decompositions. In this paper we characterize threshold graphs using the weakly decomposition, determine: density and stability number, Wiener index and Wiener polynomial for threshold graphs.

  12. Threshold current for fireball generation

    Science.gov (United States)

    Dijkhuis, Geert C.

    1982-05-01

    Fireball generation from a high-intensity circuit breaker arc is interpreted here as a quantum-mechanical phenomenon caused by severe cooling of electrode material evaporating from contact surfaces. According to the proposed mechanism, quantum effects appear in the arc plasma when the radius of one magnetic flux quantum inside solid electrode material has shrunk to one London penetration length. A formula derived for the threshold discharge current preceding fireball generation is found compatible with data reported by Silberg. This formula predicts linear scaling of the threshold current with the circuit breaker's electrode radius and concentration of conduction electrons.

  13. Nuclear threshold effects and neutron strength function

    International Nuclear Information System (INIS)

    Hategan, Cornel; Comisel, Horia

    2003-01-01

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

  14. On the Scattering of the Electron off the Hydrogen Atom and the Helium Ion Below and Above the Ionization Threshold: Temkin–Poet Model

    International Nuclear Information System (INIS)

    Yarevsky, E.; Yakovlev, S. L.; Volkov, M. V.; Elander, N.

    2014-01-01

    We generalize here the splitting approach to the long range (Coulomb) interaction for the three body scattering problem. With this approach, the exterior complex rotation technique can be applied for systems with asymptotic Coulomb interaction. We illustrate the method with calculations of the electron scattering on the hydrogen atom and positive helium ion in the frame of the Temkin–Poet model. (author)

  15. On the Scattering of the Electron off the Hydrogen Atom and the Helium Ion Below and Above the Ionization Threshold: Temkin-Poet Model

    Science.gov (United States)

    Yarevsky, E.; Yakovlev, S. L.; Elander, N.; Volkov, M. V.

    2014-08-01

    We generalize here the splitting approach to the long range (Coulomb) interaction for the three body scattering problem. With this approach, the exterior complex rotation technique can be applied for systems with asymptotic Coulomb interaction. We illustrate the method with calculations of the electron scattering on the hydrogen atom and positive helium ion in the frame of the Temkin-Poet model.

  16. Wine grape cultivar influence on the performance of models that predict the lower threshold canopy temperature of a water stress index

    Science.gov (United States)

    The calculation of a thermal based Crop Water Stress Index (CWSI) requires an estimate of canopy temperature under non-water stressed conditions. The objective of this study was to assess the influence of different wine grape cultivars on the performance of models that predict canopy temperature non...

  17. Percolation Threshold Parameters of Fluids

    Czech Academy of Sciences Publication Activity Database

    Škvor, J.; Nezbeda, Ivo

    2009-01-01

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

  18. Threshold analyses and Lorentz violation

    International Nuclear Information System (INIS)

    Lehnert, Ralf

    2003-01-01

    In the context of threshold investigations of Lorentz violation, we discuss the fundamental principle of coordinate independence, the role of an effective dynamical framework, and the conditions of positivity and causality. Our analysis excludes a variety of previously considered Lorentz-breaking parameters and opens an avenue for viable dispersion-relation investigations of Lorentz violation

  19. Targeting the underlying causes of undernutrition. Cost-effectiveness of a multifactorial personalized intervention in community-dwelling older adults: A randomized controlled trial.

    Science.gov (United States)

    van der Pols-Vijlbrief, Rachel; Wijnhoven, Hanneke A H; Bosmans, Judith E; Twisk, Jos W R; Visser, Marjolein

    2017-12-01

    Undernutrition in old age is associated with increased morbidity, mortality and health care costs. Treatment by caloric supplementation results in weight gain, but compliance is poor in the long run. Few studies targeted underlying causes of undernutrition in community-dwelling older adults. This study aimed to evaluate the cost-effectiveness of a multifactorial personalized intervention focused on eliminating or managing the underlying causes of undernutrition to prevent and reduce undernutrition in comparison with usual care. A randomized controlled trial was performed among 155 community-dwelling older adults receiving home care with or at risk of undernutrition. The intervention included a personalized action plan and 6 months support. The control group received usual care. Body weight, and secondary outcomes were measured in both groups at baseline and 6 months follow-up. Multiple imputation, linear regression and generalized estimating equation analyses were used to analyze intervention effects. In the cost-effectiveness analyses regression models were bootstrapped to estimate statistical uncertainty. This intervention showed no statistically significant effects on body weight, mid-upper arm circumference, grip strength, gait speed and 12-Item Short-Form Health Survey physical component scale as compared to usual care, but there was an effect on the 12-Item Short-Form Health Survey mental component scale (0-100) (β = 8.940, p=0.001). Borderline significant intervention effects were found for both objective and subjective physical function measures, Short Physical Performance Battery (0-12) (β = 0.56, p=0.08) and ADL-Barthel score (0-20) (β = 0.69, p=0.09). Societal costs in the intervention group were statistically non-significantly lower than in the control group (mean difference -274; 95% CI -1111; 782). Cost-effectiveness acceptability curves showed that the probability of cost-effectiveness was 0.72 at a willingness-to-pay of 1000

  20. Threshold Learning Dynamics in Social Networks

    Science.gov (United States)

    González-Avella, Juan Carlos; Eguíluz, Victor M.; Marsili, Matteo; Vega-Redondo, Fernado; San Miguel, Maxi

    2011-01-01

    Social learning is defined as the ability of a population to aggregate information, a process which must crucially depend on the mechanisms of social interaction. Consumers choosing which product to buy, or voters deciding which option to take with respect to an important issue, typically confront external signals to the information gathered from their contacts. Economic models typically predict that correct social learning occurs in large populations unless some individuals display unbounded influence. We challenge this conclusion by showing that an intuitive threshold process of individual adjustment does not always lead to such social learning. We find, specifically, that three generic regimes exist separated by sharp discontinuous transitions. And only in one of them, where the threshold is within a suitable intermediate range, the population learns the correct information. In the other two, where the threshold is either too high or too low, the system either freezes or enters into persistent flux, respectively. These regimes are generally observed in different social networks (both complex or regular), but limited interaction is found to promote correct learning by enlarging the parameter region where it occurs. PMID:21637714

  1. Re-examination of the threshold energy surface in copper

    International Nuclear Information System (INIS)

    King, W.E.; Benedek, R.; Merkle, K.L.; Meshii, M.

    1981-01-01

    Radiation-induced defect production in copper has been studied using in-situ electrical resistivity damage-rate measurements in the HVEM and molecular dynamics simulations. Analysis of the results yields a threshold energy surface characterized by two isolated pockets of low threshold energy centered at and surrounded by regions of much higher threshold energy; the corresponding damage function exhibits a plateau at 0.65 Frenkel pairs. A Frenkel pair resistivity of (2.75/sub -0.2/ + 0 6 ) x 10 - 4 Ω-cm is proposed. A model damage function is constructed and compared to results from ion irradiation damage-rate measurements. 7 figures

  2. Reduced risk of heart failure with intensified multifactorial intervention in individuals with type 2 diabetes and microalbuminuria: 21 years of follow-up in the randomised Steno-2 study.

    Science.gov (United States)

    Oellgaard, Jens; Gæde, Peter; Rossing, Peter; Rørth, Rasmus; Køber, Lars; Parving, Hans-Henrik; Pedersen, Oluf

    2018-05-30

    In type 2 diabetes mellitus, heart failure is a frequent, potentially fatal and often forgotten complication. Glucose-lowering agents and adjuvant therapies modify the risk of heart failure. We recently reported that 7.8 years of intensified compared with conventional multifactorial intervention in individuals with type 2 diabetes and microalbuminuria in the Steno-2 study reduced the risk of cardiovascular disease and prolonged life over 21.2 years of follow-up. In this post hoc analysis, we examine the impact of intensified multifactorial intervention on the risk of hospitalisation for heart failure. One hundred and sixty individuals were randomised to conventional or intensified multifactorial intervention, using sealed envelopes. The trial was conducted using the Prospective, Randomised, Open, Blinded Endpoints (PROBE) design. After 7.8 years, all individuals were offered intensified therapy and the study continued as an observational follow-up study for an additional 13.4 years. Heart-failure hospitalisations were adjudicated from patient records by an external expert committee blinded for treatment allocation. Event rates were compared using a Cox regression model adjusted for age and sex. Eighty patients were assigned to each treatment group. Ten patients undergoing intensive therapy vs 24 undergoing conventional therapy were hospitalised for heart failure during follow-up. The HR (95% CI) was 0.30 (0.14, 0.64), p = 0.002 in the intensive-therapy group compared with the conventional-therapy group. Including death in the endpoint did not lead to an alternate overall outcome; HR 0.51 (0.34, 0.76), p = 0.001. In a pooled cohort analysis, an increase in plasma N-terminal pro-B-type natriuretic peptide (NT-proBNP) during the first two years of the trial was associated with incident heart failure. Intensified, multifactorial intervention for 7.8 years in type 2 diabetic individuals with microalbuminuria reduced the risk of hospitalisation for heart

  3. Image Segmentation using a Refined Comprehensive Learning Particle Swarm Optimizer for Maximum Tsallis Entropy Thresholding

    OpenAIRE

    L. Jubair Ahmed; A. Ebenezer Jeyakumar

    2013-01-01

    Thresholding is one of the most important techniques for performing image segmentation. In this paper to compute optimum thresholds for Maximum Tsallis entropy thresholding (MTET) model, a new hybrid algorithm is proposed by integrating the Comprehensive Learning Particle Swarm Optimizer (CPSO) with the Powell’s Conjugate Gradient (PCG) method. Here the CPSO will act as the main optimizer for searching the near-optimal thresholds while the PCG method will be used to fine tune the best solutio...

  4. Narrow structure in Λd scattering near the Σ threshold (Σ3He states)

    International Nuclear Information System (INIS)

    Gibson, B.F.; Afnan, I.R.

    1991-01-01

    A separable-potential, Faddeev-type calculation of Λ-deuteron scattering near the threshold for Σ production is shown to produce structure (a resonance peak) in the cross section which lies below the Σ threshold for two different YN (ΛN-ΣN coupled-channel) potential models. In one case the ΣNN eigenvalue corresponds to a pole which lies below threshold (bound) and in the second case the poles lies above the threshold

  5. Economic evaluation of a multifactorial, interdisciplinary intervention versus usual care to reduce frailty in frail older people.

    Science.gov (United States)

    Fairhall, Nicola; Sherrington, Catherine; Kurrle, Susan E; Lord, Stephen R; Lockwood, Keri; Howard, Kirsten; Hayes, Alison; Monaghan, Noeline; Langron, Colleen; Aggar, Christina; Cameron, Ian D

    2015-01-01

    To compare the costs and cost-effectiveness of a multifactorial interdisciplinary intervention versus usual care for older people who are frail. Cost-effectiveness study embedded within a randomized controlled trial. Community-based intervention in Sydney, Australia. A total of 241 community-dwelling people 70 years or older who met the Cardiovascular Health Study criteria for frailty. A 12-month multifactorial, interdisciplinary intervention targeting identified frailty characteristics versus usual care. Health and social service use, frailty, and health-related quality of life (EQ-5D) were measured over the 12-month intervention period. The difference between the mean cost per person for 12 months in the intervention and control groups (incremental cost) and the ratio between incremental cost and effectiveness were calculated. A total of 216 participants (90%) completed the study. The prevalence of frailty was 14.7% lower in the intervention group compared with the control group at 12 months (95% CI 2.4%-27.0%; P = .02). There was no significant between-group difference in EQ-5D utility scores. The cost for 1 extra person to transition out of frailty was $A15,955 (at 2011 prices). In the "very frail" subgroup (participants met >3 Cardiovascular Health Study frailty criteria), the intervention was both more effective and less costly than the control. A cost-effectiveness acceptability curve shows that the intervention would be cost-effective with 80% certainty if decision makers were willing to pay $A50,000 per extra person transitioning from frailty. In the very frail subpopulation, this reduced to $25,000. For frail older people residing in the community, a 12-month multifactorial intervention provided better value for money than usual care, particularly for the very frail, in whom it has a high probability of being cost saving, as well as effective. Trial registration: ACTRN12608000250336. Copyright © 2015 AMDA – The Society for Post-Acute and Long-Term Care

  6. Use of erythropoietin is associated with threshold retinopathy of prematurity (ROP) in preterm ELBW neonates: a retrospective, cohort study from two large tertiary NICUs in Italy.

    Science.gov (United States)

    Manzoni, Paolo; Memo, Luigi; Mostert, Michael; Gallo, Elena; Guardione, Roberta; Maestri, Andrea; Saia, Onofrio Sergio; Opramolla, Anna; Calabrese, Sara; Tavella, Elena; Luparia, Martina; Farina, Daniele

    2014-09-01

    Retinopathy of prematurity (ROP) is a multifactorial disease with evidence of many associated risk factors. Erythropoietin has been reported to be associated with this disorder in a murine model, as well as in humans in some single-center reports. We reviewed the data from two large tertiary NICUs in Italy to test the hypothesis that the use of erythropoietin may be associated with the development of the most severe stages of ROP in extremely low birth weight (ELBW) neonates. Retrospective study by review of patient charts and eye examination index cards on infants with birth weight large tertiary NICUs in Northern Italy (Sant'Anna Hospital NICU in Torino, and Ca' Foncello Hospital Neonatology in Treviso) in the years 2005 to 2007. Standard protocol of administration of EPO in the two NICUs consisted of 250 UI/kg three times a week for 6-week courses (4-week in 1001-1500g infants). Univariate analysis was performed to assess whether the use of EPO was associated with severe (threshold) ROP. A control, multivariate statistical analysis was performed by entering into a logistic regression model a number of neonatal and perinatal variables that - in univariate analysis - had been associated with threshold ROP. During the study period, 211 ELBW infants were born at the two facilities and survived till discharge. Complete data were obtained for 197 of them. Threshold retinopathy of prematurity occurred in 26.9% (29 of 108) of ELBW infants who received erythropoietin therapy, as compared with 13.5% (12 of 89) of those who did not receive erythropoietin (OR 2.35; 95% CI 1.121-4.949; p=0.02 in univariate analysis, and p=0.04 at multivariate logistic regression after controlling for the following variables: birth weight, gestational age, days on supplemental oxygen, systemic fungal infection, vaginal delivery). Use of erythropoietin was not significantly associated with other major sequelae of prematurity (intraventricular hemorrhage, bronchopulmonary dysplasia, necrotizing

  7. Threshold condition for nonlinear tearing modes in tokamaks

    Energy Technology Data Exchange (ETDEWEB)

    Zabiego, M.F. [Association Euratom-CEA, Centre d`Etudes de Cadarache, 13 - Saint-Paul-lez-Durance (France). Dept. de Recherches sur la Fusion Controlee; Callen, J.D. [Wisconsin Univ., Madison, WI (United States). Dept. of Nuclear Engineering and Engineering Physics

    1996-04-01

    Low-mode-number tearing mode nonlinear evolution is analyzed emphasizing the need for a threshold condition, to account for observations in tokamaks. The discussion is illustrated by two models recently introduced in the literature. Introducing a threshold condition in the tearing mode stability analysis is found to reveal some bifurcation points and thus domains of intrinsic stability in the island dynamics operational space. (author). 19 refs.

  8. Total water content thresholds for shallow landslides, Outer Western Carpathians

    Czech Academy of Sciences Publication Activity Database

    Bil, M.; Andrašík, R.; Zahradníček, Pavel; Kubeček, J.; Sedonik, J.; Štěpánek, Petr

    2016-01-01

    Roč. 13, č. 2 (2016), s. 337-347 ISSN 1612-510X R&D Projects: GA ČR GA13-19831S; GA MŠk(CZ) EE2.3.20.0248 Institutional support: RVO:67179843 Keywords : data quality -control * debris flows * rainfall thresholds * equivalent * depth * failures * example * europe * model * Landslides * Threshold * Snowmelt * Time series * Antecedent rainfall * Outer Western Carpathians Subject RIV: EH - Ecology, Behaviour Impact factor: 3.657, year: 2016

  9. Threshold condition for nonlinear tearing modes in tokamaks

    International Nuclear Information System (INIS)

    Zabiego, M.F.; Callen, J.D.

    1996-04-01

    Low-mode-number tearing mode nonlinear evolution is analyzed emphasizing the need for a threshold condition, to account for observations in tokamaks. The discussion is illustrated by two models recently introduced in the literature. Introducing a threshold condition in the tearing mode stability analysis is found to reveal some bifurcation points and thus domains of intrinsic stability in the island dynamics operational space. (author)

  10. A new, accurate predictive model for incident hypertension

    DEFF Research Database (Denmark)

    Völzke, Henry; Fung, Glenn; Ittermann, Till

    2013-01-01

    Data mining represents an alternative approach to identify new predictors of multifactorial diseases. This work aimed at building an accurate predictive model for incident hypertension using data mining procedures.......Data mining represents an alternative approach to identify new predictors of multifactorial diseases. This work aimed at building an accurate predictive model for incident hypertension using data mining procedures....

  11. The issue of threshold states

    International Nuclear Information System (INIS)

    Luck, L.

    1994-01-01

    The states which have not joined the Non-proliferation Treaty nor have undertaken any other internationally binding commitment not to develop or otherwise acquire nuclear weapons are considered a threshold states. Their nuclear status is rendered opaque as a conscious policy. Nuclear threshold status remains a key disarmament issue. For those few states, as India, Pakistan, Israel, who have put themselves in this position, the security returns have been transitory and largely illusory. The cost to them, and to the international community committed to the norm of non-proliferation, has been huge. The decisions which could lead to recovery from the situation in which they find themselves are essentially at their own hands. Whatever assistance the rest of international community is able to extend, it will need to be accompanied by a vital political signal

  12. Realistic Realizations Of Threshold Circuits

    Science.gov (United States)

    Razavi, Hassan M.

    1987-08-01

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

  13. Root finding with threshold circuits

    Czech Academy of Sciences Publication Activity Database

    Jeřábek, Emil

    2012-01-01

    Roč. 462, Nov 30 (2012), s. 59-69 ISSN 0304-3975 R&D Projects: GA AV ČR IAA100190902; GA MŠk(CZ) 1M0545 Institutional support: RVO:67985840 Keywords : root finding * threshold circuit * power series Subject RIV: BA - General Mathematics Impact factor: 0.489, year: 2012 http://www.sciencedirect.com/science/article/pii/S0304397512008006#

  14. Reduced risk of heart failure with intensified multifactorial intervention in individuals with type 2 diabetes and microalbuminuria

    DEFF Research Database (Denmark)

    Oellgaard, Jens; Gæde, Peter; Rossing, Peter

    2018-01-01

    of hospitalisation for heart failure. METHODS: One hundred and sixty individuals were randomised to conventional or intensified multifactorial intervention, using sealed envelopes. The trial was conducted using the Prospective, Randomised, Open, Blinded Endpoints (PROBE) design. After 7.8 years, all individuals were......AIMS/HYPOTHESIS: In type 2 diabetes mellitus, heart failure is a frequent, potentially fatal and often forgotten complication. Glucose-lowering agents and adjuvant therapies modify the risk of heart failure. We recently reported that 7.8 years of intensified compared with conventional...... offered intensified therapy and the study continued as an observational follow-up study for an additional 13.4 years. Heart-failure hospitalisations were adjudicated from patient records by an external expert committee blinded for treatment allocation. Event rates were compared using a Cox regression...

  15. Prevalence of sexual desire and satisfaction among patients with screen-detected diabetes and impact of intensive multifactorial treatment

    DEFF Research Database (Denmark)

    Pedersen, Mette B.; Giraldi, Annamaria; Kristensen, Ellids

    2015-01-01

    of 968 patients with screen-detected type 2 diabetes. MAIN OUTCOME MEASURES: Low sexual desire and low sexual satisfaction. RESULTS: Mean (standard deviation, SD) age was 64.9 (6.9) years. The prevalence of low sexual desire was 53% (RC) and 54% (IT) among women, and 24% (RC) and 25% (IT) among men......OBJECTIVE: Sexual problems are common in people with diabetes. It is unknown whether early detection of diabetes and subsequent intensive multifactorial treatment (IT) are associated with sexual health. We report the prevalence of low sexual desire and low sexual satisfaction among people....... The prevalence of low sexual satisfaction was 23% (RC) and 18% (IT) among women, and 27% (RC) and 37% (IT) among men. Among men, the prevalence of low sexual satisfaction was significantly higher in the IT group than in the RC group, p = 0.01. CONCLUSION: Low sexual desire and low satisfaction are frequent among...

  16. Design proposal for door thresholds

    Directory of Open Access Journals (Sweden)

    Smolka Radim

    2017-01-01

    Full Text Available Panels for openings in structures have always been an essential and integral part of buildings. Their importance in terms of a building´s functionality was not recognised. However, the general view on this issue has changed from focusing on big planar segments and critical details to sub-elements of these structures. This does not only focus on the forms of connecting joints but also on the supporting systems that keep the panels in the right position and ensure they function properly. One of the most strained segments is the threshold structure, especially the entrance door threshold structure. It is the part where substantial defects in construction occur in terms of waterproofing, as well as in the static, thermal and technical functions thereof. In conventional buildings, this problem is solved by pulling the floor structure under the entrance door structure and subsequently covering it with waterproofing material. This system cannot work effectively over the long term so local defects occur. A proposal is put forward to solve this problem by installing a sub-threshold door coupler made of composite materials. The coupler is designed so that its variability complies with the required parameters for most door structures on the European market.

  17. Cost-effectiveness analysis of a multifactorial fall prevention intervention in older home care clients at risk for falling.

    Science.gov (United States)

    Isaranuwatchai, Wanrudee; Perdrizet, Johnna; Markle-Reid, Maureen; Hoch, Jeffrey S

    2017-09-01

    Falls among older adults can cause serious morbidity and pose economic burdens on society. Older age is a known risk factor for falls and age has been shown to influence the effectiveness of fall prevention programs. To our knowledge, no studies have explicitly investigated whether cost-effectiveness of a multifactorial fall prevention intervention (the intervention) is influenced by age. This economic evaluation explores: 1) the cost-effectiveness of a multifactorial fall prevention intervention compared to usual care for community-dwelling adults ≥ 75 years at risk of falling in Canada; and 2) the influence of age on the cost-effectiveness of the intervention. Net benefit regression was used to examine the cost-effectiveness of the intervention with willingness-to-pay values ranging from $0-$50,000. Effects were measured as change in the number of falls, from baseline to 6-month follow-up. Costs were measured using a societal perspective. The cost-effectiveness analysis was conducted for both the total sample and by age subgroups (75-84 and 85+ years). For the total sample, the intervention was not economically attractive. However, the intervention was cost-effective at higher willingness-to-pay (WTP) (≥ $25,000) for adults 75-84 years and at lower WTP (cost-effectiveness of the intervention depends on age and decision makers' WTP to prevent falls. Understanding the influence of age on the cost-effectiveness of an intervention may help to target resources to those who benefit most. Retrospectively registered. Clinicaltrials.gov identifier: NCT00463658 (18 April 2007).

  18. Color difference thresholds in dentistry.

    Science.gov (United States)

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

    2015-01-01

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

  19. Bedding material affects mechanical thresholds, heat thresholds and texture preference

    Science.gov (United States)

    Moehring, Francie; O’Hara, Crystal L.; Stucky, Cheryl L.

    2015-01-01

    It has long been known that the bedding type animals are housed on can affect breeding behavior and cage environment. Yet little is known about its effects on evoked behavior responses or non-reflexive behaviors. C57BL/6 mice were housed for two weeks on one of five bedding types: Aspen Sani Chips® (standard bedding for our institute), ALPHA-Dri®, Cellu-Dri™, Pure-o’Cel™ or TEK-Fresh. Mice housed on Aspen exhibited the lowest (most sensitive) mechanical thresholds while those on TEK-Fresh exhibited 3-fold higher thresholds. While bedding type had no effect on responses to punctate or dynamic light touch stimuli, TEK-Fresh housed animals exhibited greater responsiveness in a noxious needle assay, than those housed on the other bedding types. Heat sensitivity was also affected by bedding as animals housed on Aspen exhibited the shortest (most sensitive) latencies to withdrawal whereas those housed on TEK-Fresh had the longest (least sensitive) latencies to response. Slight differences between bedding types were also seen in a moderate cold temperature preference assay. A modified tactile conditioned place preference chamber assay revealed that animals preferred TEK-Fresh to Aspen bedding. Bedding type had no effect in a non-reflexive wheel running assay. In both acute (two day) and chronic (5 week) inflammation induced by injection of Complete Freund’s Adjuvant in the hindpaw, mechanical thresholds were reduced in all groups regardless of bedding type, but TEK-Fresh and Pure-o’Cel™ groups exhibited a greater dynamic range between controls and inflamed cohorts than Aspen housed mice. PMID:26456764

  20. Rainfall thresholds and flood warning: an operative case study

    Directory of Open Access Journals (Sweden)

    V. Montesarchio

    2009-02-01

    Full Text Available An operative methodology for rainfall thresholds definition is illustrated, in order to provide at critical river section optimal flood warnings. Threshold overcoming could produce a critical situation in river sites exposed to alluvial risk and trigger the prevention and emergency system alert. The procedure for the definition of critical rainfall threshold values is based both on the quantitative precipitation observed and the hydrological response of the basin. Thresholds values specify the precipitation amount for a given duration that generates a critical discharge in a given cross section and are estimated by hydrological modelling for several scenarios (e.g.: modifying the soil moisture conditions. Some preliminary results, in terms of reliability analysis (presence of false alarms and missed alarms, evaluated using indicators like hit rate and false alarm rate for the case study of Mignone River are presented.

  1. Higgs-Stoponium Mixing Near the Stop-Antistop Threshold

    CERN Document Server

    Bodwin, Geoffrey T; Wagner, Carlos E M

    2016-01-01

    Supersymmetric extensions of the standard model contain additional heavy neutral Higgs bosons that are coupled to heavy scalar top quarks (stops). This system exhibits interesting field theoretic phenomena when the Higgs mass is close to the stop-antistop production threshold. Existing work in the literature has examined the digluon-to-diphoton cross section near threshold and has focused on enhancements in the cross section that might arise either from the perturbative contributions to the Higgs-to-digluon and Higgs-to-diphoton form factors or from mixing of the Higgs boson with stoponium states. Near threshold, enhancements in the relevant amplitudes that go as inverse powers of the stop-antistop relative velocity require resummations of perturbation theory and/or nonperturbative treatments. We present a complete formulation of threshold effects at leading order in the stop-antistop relative velocity in terms of nonrelativistic effective field theory. We give detailed numerical calculations for the case in ...

  2. Dynamical fusion thresholds in macroscopic and microscopic theories

    International Nuclear Information System (INIS)

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

    1983-01-01

    Macroscopic and microscopic results demonstrating the existence of dynamical fusion thresholds are presented. For macroscopic theories, it is shown that the extra-push dynamics is sensitive to some details of the models used, e.g. the shape parametrization and the type of viscosity. The dependence of the effect upon the charge and angular momentum of the system is also studied. Calculated macroscopic results for mass-symmetric systems are compared to experimental mass-asymmetric results by use of a tentative scaling procedure, which takes into account both the entrance-channel and the saddle-point regions of configuration space. Two types of dynamical fusion thresholds occur in TDHF studies: (1) the microscopic analogue of the macroscopic extra push threshold, and (2) the relatively high energy at which the TDHF angular momentum window opens. Both of these microscopic thresholds are found to be very sensitive to the choice of the effective two-body interaction

  3. Rainfall thresholds for the initiation of debris flows at La Honda, California

    Science.gov (United States)

    Wilson, R.C.; Wieczorek, G.F.

    1995-01-01

    A simple numerical model, based on the physical analogy of a leaky barrel, can simulate significant features of the interaction between rainfall and shallow-hillslope pore pressures. The leaky-barrel-model threshold is consistent with, but slightly higher than, an earlier, purely empirical, threshold. The number of debris flows triggered by a storm can be related to the time and amount by which the leaky-barrel-model response exceeded the threshold during the storm. -from Authors

  4. Contribution of nonprimate animal models in understanding the etiology of schizophrenia

    Science.gov (United States)

    Lazar, Noah L.; Neufeld, Richard W.J.; Cain, Donald P.

    2011-01-01

    Schizophrenia is a severe psychiatric disorder that is characterized by positive and negative symptoms and cognitive impairments. The etiology of the disorder is complex, and it is thought to follow a multifactorial threshold model of inheritance with genetic and neurodevelopmental contributions to risk. Human studies are particularly useful in capturing the richness of the phenotype, but they are often limited to the use of correlational approaches. By assessing behavioural abnormalities in both humans and rodents, nonprimate animal models of schizophrenia provide unique insight into the etiology and mechanisms of the disorder. This review discusses the phenomenology and etiology of schizophrenia and the contribution of current nonprimate animal models with an emphasis on how research with models of neurotransmitter dysregulation, environmental risk factors, neurodevelopmental disruption and genetic risk factors can complement the literature on schizophrenia in humans. PMID:21247514

  5. Computational analysis of thresholds for magnetophosphenes

    International Nuclear Information System (INIS)

    Laakso, Ilkka; Hirata, Akimasa

    2012-01-01

    In international guidelines, basic restriction limits on the exposure of humans to low-frequency magnetic and electric fields are set with the objective of preventing the generation of phosphenes, visual sensations of flashing light not caused by light. Measured data on magnetophosphenes, i.e. phosphenes caused by a magnetically induced electric field on the retina, are available from volunteer studies. However, there is no simple way for determining the retinal threshold electric field or current density from the measured threshold magnetic flux density. In this study, the experimental field configuration of a previous study, in which phosphenes were generated in volunteers by exposing their heads to a magnetic field between the poles of an electromagnet, is computationally reproduced. The finite-element method is used for determining the induced electric field and current in five different MRI-based anatomical models of the head. The direction of the induced current density on the retina is dominantly radial to the eyeball, and the maximum induced current density is observed at the superior and inferior sides of the retina, which agrees with literature data on the location of magnetophosphenes at the periphery of the visual field. On the basis of computed data, the macroscopic retinal threshold current density for phosphenes at 20 Hz can be estimated as 10 mA m −2 (−20% to  + 30%, depending on the anatomical model); this current density corresponds to an induced eddy current of 14 μA (−20% to  + 10%), and about 20% of this eddy current flows through each eye. The ICNIRP basic restriction limit for the induced electric field in the case of occupational exposure is not exceeded until the magnetic flux density is about two to three times the measured threshold for magnetophosphenes, so the basic restriction limit does not seem to be conservative. However, the reasons for the non-conservativeness are purely technical: removal of the highest 1% of

  6. 11 CFR 9036.1 - Threshold submission.

    Science.gov (United States)

    2010-01-01

    ... credit or debit card, including one made over the Internet, the candidate shall provide sufficient... section shall not count toward the threshold amount. (c) Threshold certification by Commission. (1) After...

  7. Nuclear thermodynamics below particle threshold

    International Nuclear Information System (INIS)

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

    2005-01-01

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

  8. Impact of a multifactorial treatment programme on clinical outcomes and cardiovascular risk estimates

    DEFF Research Database (Denmark)

    Safai, Narges; Carstensen, Bendix; Vestergaard, Henrik

    2018-01-01

    ), blood pressure (BP) and low-density lipoprotein (LDL) cholesterol as well as proportion reaching treatment targets. Our secondary outcome was to investigate changes in antidiabetic, antihypertensive and lipid-lowering treatment, together with the impact on estimated CVD risk. Linear mixed model....... SETTING: Tertiary diabetes centre in Denmark. PARTICIPANTS: Patients with type 2 diabetes (n=4299) referred to a programme with focus on treatment of hyperglycaemia, hypertension and dyslipidaemia between 1 January 2001 and 1 April 2016. OUTCOMES: Primary outcomes were changes in haemoglobin A1c (HbA1c...

  9. Compositional threshold for Nuclear Waste Glass Durability

    International Nuclear Information System (INIS)

    Kruger, Albert A.; Farooqi, Rahmatullah; Hrma, Pavel R.

    2013-01-01

    Within the composition space of glasses, a distinct threshold appears to exist that separates 'good' glasses, i.e., those which are sufficiently durable, from 'bad' glasses of a low durability. The objective of our research is to clarify the origin of this threshold by exploring the relationship between glass composition, glass structure and chemical durability around the threshold region

  10. Threshold Concepts in Finance: Student Perspectives

    Science.gov (United States)

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

    2015-01-01

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

  11. Metastability Thresholds for Anisotropic Bootstrap Percolation in Three Dimensions

    NARCIS (Netherlands)

    Enter, Aernout C.D. van; Fey, Anne

    In this paper we analyze several anisotropic bootstrap percolation models in three dimensions. We present the order of magnitude for the metastability thresholds for a fairly general class of models. In our proofs, we use an adaptation of the technique of dimensional reduction. We find that the

  12. Multifactorial control of water and saline intake: role of a2-adrenoceptors

    Directory of Open Access Journals (Sweden)

    L.A. De-Luca Jr.

    1997-04-01

    Full Text Available Water and saline intake is controlled by several mechanisms activated during dehydration. Some mechanisms, such as the production of angiotensin II and unloading of cardiovascular receptors, activate both behaviors, while others, such as the increase in blood osmolality or sodium concentration, activate water, but inhibit saline intake. Aldosterone probably activates only saline intake. Clonidine, an a2-adrenergic agonist, inhibits water and saline intake induced by these mechanisms. One model to describe the interactions between these multiple mechanisms is a wire-block diagram, where the brain circuit that controls each intake is represented by a summing point of its respective inhibiting and activating factors. The a2-adrenoceptors constitute an inhibitory factor common to both summing points

  13. Long-term multifactorial climate change impacts on mesofaunal biomass and nitrogen content

    DEFF Research Database (Denmark)

    Madsen, Mette Vestergård; Dyrnum, Kristine; Michelsen, Anders

    2015-01-01

    increased at elevated CO2, or tended do so. In contrast, enchytraeid N content decreased at elevated CO2. Soil microbial biomass N pool and litter C:N ratio also increased with elevated CO2, which suggests that mite biomasses are more coupled to microbial biomass, whereas enchytraeid biomass to a larger...... extent is governed by litter nitrogen concentration, i.e. litter quality. Structural equation modelling confirmed the positive coupling between soil microbial N content and oribatid biomass and further between oribatid and mesostigmatic biomass. The SEM also revealed a negative relationship between...... microbial N content and enchytraeid biomass. The biomass of all mesofaunal groups was reduced by spring drought, especially when combined with warming. Enchytraeid and especially collembolan biomass suffered greater drought declines than mite biomasses. We conclude that under long-term elevated CO2 exposure...

  14. On the mixing time of geographical threshold graphs

    Energy Technology Data Exchange (ETDEWEB)

    Bradonjic, Milan [Los Alamos National Laboratory

    2009-01-01

    In this paper, we study the mixing time of random graphs generated by the geographical threshold graph (GTG) model, a generalization of random geometric graphs (RGG). In a GTG, nodes are distributed in a Euclidean space, and edges are assigned according to a threshold function involving the distance between nodes as well as randomly chosen node weights. The motivation for analyzing this model is that many real networks (e.g., wireless networks, the Internet, etc.) need to be studied by using a 'richer' stochastic model (which in this case includes both a distance between nodes and weights on the nodes). We specifically study the mixing times of random walks on 2-dimensional GTGs near the connectivity threshold. We provide a set of criteria on the distribution of vertex weights that guarantees that the mixing time is {Theta}(n log n).

  15. Epidemic threshold in directed networks

    Science.gov (United States)

    Li, Cong; Wang, Huijuan; Van Mieghem, Piet

    2013-12-01

    Epidemics have so far been mostly studied in undirected networks. However, many real-world networks, such as the online social network Twitter and the world wide web, on which information, emotion, or malware spreads, are directed networks, composed of both unidirectional links and bidirectional links. We define the directionality ξ as the percentage of unidirectional links. The epidemic threshold τc for the susceptible-infected-susceptible (SIS) epidemic is lower bounded by 1/λ1 in directed networks, where λ1, also called the spectral radius, is the largest eigenvalue of the adjacency matrix. In this work, we propose two algorithms to generate directed networks with a given directionality ξ. The effect of ξ on the spectral radius λ1, principal eigenvector x1, spectral gap (λ1-λ2), and algebraic connectivity μN-1 is studied. Important findings are that the spectral radius λ1 decreases with the directionality ξ, whereas the spectral gap and the algebraic connectivity increase with the directionality ξ. The extent of the decrease of the spectral radius depends on both the degree distribution and the degree-degree correlation ρD. Hence, in directed networks, the epidemic threshold is larger and a random walk converges to its steady state faster than that in undirected networks with the same degree distribution.

  16. Computational gestalts and perception thresholds.

    Science.gov (United States)

    Desolneux, Agnès; Moisan, Lionel; Morel, Jean-Michel

    2003-01-01

    In 1923, Max Wertheimer proposed a research programme and method in visual perception. He conjectured the existence of a small set of geometric grouping laws governing the perceptual synthesis of phenomenal objects, or "gestalt" from the atomic retina input. In this paper, we review this set of geometric grouping laws, using the works of Metzger, Kanizsa and their schools. In continuation, we explain why the Gestalt theory research programme can be translated into a Computer Vision programme. This translation is not straightforward, since Gestalt theory never addressed two fundamental matters: image sampling and image information measurements. Using these advances, we shall show that gestalt grouping laws can be translated into quantitative laws allowing the automatic computation of gestalts in digital images. From the psychophysical viewpoint, a main issue is raised: the computer vision gestalt detection methods deliver predictable perception thresholds. Thus, we are set in a position where we can build artificial images and check whether some kind of agreement can be found between the computationally predicted thresholds and the psychophysical ones. We describe and discuss two preliminary sets of experiments, where we compared the gestalt detection performance of several subjects with the predictable detection curve. In our opinion, the results of this experimental comparison support the idea of a much more systematic interaction between computational predictions in Computer Vision and psychophysical experiments.

  17. Threshold Games and Cooperation on Multiplayer Graphs.

    Directory of Open Access Journals (Sweden)

    Kaare B Mikkelsen

    Full Text Available The study investigates the effect on cooperation in multiplayer games, when the population from which all individuals are drawn is structured-i.e. when a given individual is only competing with a small subset of the entire population.To optimize the focus on multiplayer effects, a class of games were chosen for which the payoff depends nonlinearly on the number of cooperators-this ensures that the game cannot be represented as a sum of pair-wise interactions, and increases the likelihood of observing behaviour different from that seen in two-player games. The chosen class of games are named "threshold games", and are defined by a threshold, M > 0, which describes the minimal number of cooperators in a given match required for all the participants to receive a benefit. The model was studied primarily through numerical simulations of large populations of individuals, each with interaction neighbourhoods described by various classes of networks.When comparing the level of cooperation in a structured population to the mean-field model, we find that most types of structure lead to a decrease in cooperation. This is both interesting and novel, simply due to the generality and breadth of relevance of the model-it is likely that any model with similar payoff structure exhibits related behaviour. More importantly, we find that the details of the behaviour depends to a large extent on the size of the immediate neighbourhoods of the individuals, as dictated by the network structure. In effect, the players behave as if they are part of a much smaller, fully mixed, population, which we suggest an expression for.

  18. Threshold effect under nonlinear limitation of the intensity of high-power light

    International Nuclear Information System (INIS)

    Tereshchenko, S A; Podgaetskii, V M; Gerasimenko, A Yu; Savel'ev, M S

    2015-01-01

    A model is proposed to describe the properties of limiters of high-power laser radiation, which takes into account the threshold character of nonlinear interaction of radiation with the working medium of the limiter. The generally accepted non-threshold model is a particular case of the threshold model if the threshold radiation intensity is zero. Experimental z-scan data are used to determine the nonlinear optical characteristics of media with carbon nanotubes, polymethine and pyran dyes, zinc selenide, porphyrin-graphene and fullerene-graphene. A threshold effect of nonlinear interaction between laser radiation and some of investigated working media of limiters is revealed. It is shown that the threshold model more adequately describes experimental z-scan data. (nonlinear optical phenomena)

  19. Type 1 Diabetes and Its Multi-Factorial Pathogenesis: The Putative Role of NK Cells.

    Science.gov (United States)

    Marca, Valeria La; Gianchecchi, Elena; Fierabracci, Alessandra

    2018-03-10

    Type 1 diabetes (T1D) affects millions of people worldwide and is the prevalent form of all pediatric diabetes diagnoses. T1D is recognized to have an autoimmune etiology, since failure in specific self-tolerance mechanisms triggers immune reactions towards self-antigens and causes disease onset. Among all the different immunocytes involved in T1D etiopathogenesis, a relevant role of natural killer cells (NKs) is currently emerging. NKs represent the interface between innate and adaptive immunity; they intervene in the defense against infections and present, at the same time, typical features of the adaptive immune cells, such as expansion and generation of memory cells. Several recent studies, performed both in animal models and in human diabetic patients, revealed aberrations in NK cell frequency and functionality in the peripheral blood and in damaged tissues, suggesting their possible redirection towards affected tissues. NKs oscillate from a quiescent to an activated state through a delicate balance of activating and inhibitory signals transduced via surface receptors. Further accurate investigations are needed to elucidate the exact role of NKs in T1D, in order to develop novel immune-based therapies able to reduce the disease risk or delay its onset.

  20. Multifactorial skin barrier deficiency and atopic dermatitis: Essential topics to prevent the atopic march.

    Science.gov (United States)

    Egawa, Gyohei; Kabashima, Kenji

    2016-08-01

    Atopic dermatitis (AD) is the most common inflammatory skin disease in the industrialized world and has multiple causes. Over the past decade, data from both experimental models and patients have highlighted the primary pathogenic role of skin barrier deficiency in patients with AD. Increased access of environmental agents into the skin results in chronic inflammation and contributes to the systemic "atopic (allergic) march." In addition, persistent skin inflammation further attenuates skin barrier function, resulting in a positive feedback loop between the skin epithelium and the immune system that drives pathology. Understanding the mechanisms of skin barrier maintenance is essential for improving management of AD and limiting downstream atopic manifestations. In this article we review the latest developments in our understanding of the pathomechanisms of skin barrier deficiency, with a particular focus on the formation of the stratum corneum, the outermost layer of the skin, which contributes significantly to skin barrier function. Copyright © 2016 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.

  1. A Multifactorial Approach to Sport-Related Concussion Prevention and Education: Application of the Socioecological Framework.

    Science.gov (United States)

    Register-Mihalik, Johna; Baugh, Christine; Kroshus, Emily; Y Kerr, Zachary; Valovich McLeod, Tamara C

    2017-03-01

    To offer an overview of sport-related concussion (SRC) prevention and education strategies in the context of the socioecological framework (SEF). Athletic trainers (ATs) will understand the many factors that interact to influence SRC prevention and the implications of these interactions for effective SRC education. Concussion is a complex injury that is challenging to identify and manage, particularly when athletes fail to disclose symptoms to their health care providers. Education is 1 strategy for increasing disclosure. However, limited information addresses how ATs can integrate the many factors that may influence the effectiveness of SRC education into their specific settings. Public health models provide an example through the SEF, which highlights the interplay among various levels of society and sport that can facilitate SRC prevention strategies, including education. For ATs to develop appropriate SRC prevention strategies, a framework for application is needed. A growing body of information concerning SRC prevention indicates that knowledge alone is insufficient to change concussion-related behaviors. The SEF allows this information to be considered at levels such as policy and societal, community, interpersonal (relationships), and intrapersonal (athlete). The use of such a framework will facilitate more comprehensive SRC prevention efforts that can be applied in all athletic training practice settings. Clinical Applications: Athletic trainers can use this information as they plan SRC prevention strategies in their specific settings. This approach will aid in addressing the layers of complexity that exist when developing a concussion-management policy and plan.

  2. THE USE OF THE MULTI-FACTORIAL GRID IN THE SELECTION OF THE ENTRY STRATEGIES OF OMV AG IN THE ROMANIAN MARKET

    Directory of Open Access Journals (Sweden)

    Danciu Victor

    2009-05-01

    Full Text Available The foreign market entry is a strategic choice of any company. The firms use a practical approach in order to select and utilize the most appropriate market entry strategies and modes. This paper aims at showing how the multi-factorial grid can check up t

  3. Multifactorial Biological Modulation of Warm Ischemia Reperfusion Injury in Liver Transplantation From Non-Heart-Beating Donors Eliminates Primary Nonfunction and Reduces Bile Salt Toxicity

    NARCIS (Netherlands)

    Monbaliu, Diethard; Vekemans, Katrien; Hoekstra, Harm; Vaahtera, Lauri; Libbrecht, Louis; Derveaux, Katelijne; Parkkinen, Jaakko; Liu, Qiang; Heedfeld, Veerle; Wylin, Tine; Deckx, Hugo; Zeegers, Marcel; Balligand, Erika; Buurman, Wim; van Pelt, Jos; Porte, Robert J.; Pirenne, Jacques

    Objective: To design a multifactorial biological modulation approach targeting ischemia reperfusion injury to augment viability of porcine liver grafts from non-heart-beating donors (NHBD). Background Data: Liver Transplantation (LTx) from NHBD is associated with an increased risk of primary

  4. Cost-effectiveness of nurse-led multifactorial care to prevent or postpone new disabilities in community-living older people : Results of a cluster randomized trial

    NARCIS (Netherlands)

    Suijker, Jacqueline J.; MacNeil-Vroomen, Janet L.; van Rijn, Marjon; Buurman, Bianca M.; de Rooij, Sophia E.; van Charente, Eric P. Moll; Bosmans, Judith E.

    2017-01-01

    Objective To evaluate the cost-effectiveness of nurse-led multifactorial care to prevent or postpone new disabilities in community-living older people in comparison with usual care. Methods We conducted cost-effectiveness and cost-utility analyses alongside a cluster randomized trial with one-year

  5. Cost-effectiveness of nurse-led multifactorial care to prevent or postpone new disabilities in community-living older people: Results of a cluster randomized trial

    NARCIS (Netherlands)

    Suijker, Jacqueline J.; MacNeil-Vroomen, Janet L.; van Rijn, Marjon; Buurman, Bianca M.; de Rooij, Sophia E.; Moll van Charante, Eric P.; Bosmans, Judith E.

    2017-01-01

    Objective To evaluate the cost-effectiveness of nurse-led multifactorial care to prevent or postpone new disabilities in community-living older people in comparison with usual care. Methods We conducted cost-effectiveness and cost-utility analyses alongside a cluster randomized trial with one-year

  6. Cost-effectiveness of nurse-led multifactorial care to prevent or postpone new disabilities in community-living older people : Results of a cluster randomized trial

    NARCIS (Netherlands)

    Suijker, Jacqueline J; MacNeil-Vroomen, Janet L; van Rijn, Marjon; Buurman, Bianca M; de Rooij, Sophia E; Moll van Charante, Eric P; Bosmans, Judith E

    2017-01-01

    OBJECTIVE: To evaluate the cost-effectiveness of nurse-led multifactorial care to prevent or postpone new disabilities in community-living older people in comparison with usual care. METHODS: We conducted cost-effectiveness and cost-utility analyses alongside a cluster randomized trial with one-year

  7. Hard decoding algorithm for optimizing thresholds under general Markovian noise

    Science.gov (United States)

    Chamberland, Christopher; Wallman, Joel; Beale, Stefanie; Laflamme, Raymond

    2017-04-01

    Quantum error correction is instrumental in protecting quantum systems from noise in quantum computing and communication settings. Pauli channels can be efficiently simulated and threshold values for Pauli error rates under a variety of error-correcting codes have been obtained. However, realistic quantum systems can undergo noise processes that differ significantly from Pauli noise. In this paper, we present an efficient hard decoding algorithm for optimizing thresholds and lowering failure rates of an error-correcting code under general completely positive and trace-preserving (i.e., Markovian) noise. We use our hard decoding algorithm to study the performance of several error-correcting codes under various non-Pauli noise models by computing threshold values and failure rates for these codes. We compare the performance of our hard decoding algorithm to decoders optimized for depolarizing noise and show improvements in thresholds and reductions in failure rates by several orders of magnitude. Our hard decoding algorithm can also be adapted to take advantage of a code's non-Pauli transversal gates to further suppress noise. For example, we show that using the transversal gates of the 5-qubit code allows arbitrary rotations around certain axes to be perfectly corrected. Furthermore, we show that Pauli twirling can increase or decrease the threshold depending upon the code properties. Lastly, we show that even if the physical noise model differs slightly from the hypothesized noise model used to determine an optimized decoder, failure rates can still be reduced by applying our hard decoding algorithm.

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

    Directory of Open Access Journals (Sweden)

    Tatjana Barazon

    2010-04-01

    philosophical, artistic or scientific, it tends to free itself from rigid or fixed models and accepts change and development as the fundamental nature of things. Thinking thresholds as a method of thought progress cannot be done in a single process and therefore asks for participation in its proper nature. The soglitude springs namely from the acceptance of a multitude of points of view, as it is shown by the numerous contributions we present in this issue ‘Seuils, Thresholds, Soglitudes’ of Conserveries mémorielles.

  9. Threshold condition for nonlinear tearing modes in tokamaks

    International Nuclear Information System (INIS)

    Zabiego, M.F.; Callen, J.D.

    1996-03-01

    Low-mode-number tearing, mode nonlinear evolution is analyzed emphasizing the need for a threshold condition, to account for observations in tokamaks. The discussion is illustrated by two models recently introduced in the literature. The models can be compared with the available data and/or serve as a basis for planning some experiments in order to either test theory (by means of beta-limit scaling laws, as proposed in this paper) or attempt to control undesirable tearing modes. Introducing a threshold condition in the tearing mode stability analysis is found to reveal some bifurcation points and thus domains of intrinsic stability in the island dynamics operational space

  10. Estimation in Discretely Observed Diffusions Killed at a Threshold

    DEFF Research Database (Denmark)

    Bibbona, Enrico; Ditlevsen, Susanne

    2013-01-01

    are modelled as discretely observed diffusions which are killed when the threshold is reached. Statistical inference is often based on a misspecified likelihood ignoring the presence of the threshold causing severe bias, e.g. the bias incurred in the drift parameters of the Ornstein–Uhlenbeck model...... for biological relevant parameters can be up to 25–100 per cent. We compute or approximate the likelihood function of the killed process. When estimating from a single trajectory, considerable bias may still be present, and the distribution of the estimates can be heavily skewed and with a huge variance...

  11. Management of multifactorial idiopathic epilepsy in EL mice with caloric restriction and the ketogenic diet: role of glucose and ketone bodies

    Directory of Open Access Journals (Sweden)

    Mantis John G

    2004-10-01

    Full Text Available Abstract Background The high fat, low carbohydrate ketogenic diet (KD was developed as an alternative to fasting for seizure management. While the mechanisms by which fasting and the KD inhibit seizures remain speculative, alterations in brain energy metabolism are likely involved. We previously showed that caloric restriction (CR inhibits seizure susceptibility by reducing blood glucose in the epileptic EL mouse, a natural model for human multifactorial idiopathic epilepsy. In this study, we compared the antiepileptic and anticonvulsant efficacy of the KD with that of CR in adult EL mice with active epilepsy. EL mice that experienced at least 15 recurrent complex partial seizures were fed either a standard diet unrestricted (SD-UR or restricted (SD-R, and either a KD unrestricted (KD-UR or restricted (KD-R. All mice were fasted for 14 hrs prior to diet initiation. A new experimental design was used where each mouse in the diet-restricted groups served as its own control to achieve a 20–23% body weight reduction. Seizure susceptibility, body weights, and the levels of plasma glucose and β-hydroxybutyrate were measured once/week over a nine-week treatment period. Results Body weights and blood glucose levels remained high over the testing period in the SD-UR and the KD-UR groups, but were significantly (p Conclusions The results indicate that seizure susceptibility in EL mice is dependent on plasma glucose levels and that seizure control is more associated with the amount than with the origin of dietary calories. Also, CR underlies the antiepileptic and anticonvulsant action of the KD in EL mice. A transition from glucose to ketone bodies for energy is predicted to manage EL epileptic seizures through multiple integrated changes of inhibitory and excitatory neural systems.

  12. What Is the Optimal Threshold at Which to Recommend Breast Biopsy?

    OpenAIRE

    Burnside, Elizabeth S.; Chhatwal, Jagpreet; Alagoz, Oguzhan

    2012-01-01

    Background A 2% threshold, traditionally used as a level above which breast biopsy recommended, has been generalized to all patients from several specific situations analyzed in the literature. We use a sequential decision analytic model considering clinical and mammography features to determine the optimal general threshold for image guided breast biopsy and the sensitivity of this threshold to variation of these features. Methodology/Principal Findings We built a decision analytical model c...

  13. Creep behavior and threshold stress of an extruded Al-6Mg-2Sc-1Zr alloy

    International Nuclear Information System (INIS)

    Deshmukh, S.P.; Mishra, R.S.; Kendig, K.L.

    2004-01-01

    Creep experiments were performed on extruded Al-6Mg-2Sc-1Zr (wt.%) alloy in a temperature range of 423-533 K. A threshold type creep behavior was measured and explained by observed dislocation-particle interactions. The experimental threshold stress values at various temperatures were compared with existing theoretical models. None of the available models could account for the decrease in threshold creep strength with increasing temperature

  14. Risk thresholds for alcohol consumption

    DEFF Research Database (Denmark)

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

    2018-01-01

    previous cardiovascular disease. METHODS: We did a combined analysis of individual-participant data from three large-scale data sources in 19 high-income countries (the Emerging Risk Factors Collaboration, EPIC-CVD, and the UK Biobank). We characterised dose-response associations and calculated hazard......BACKGROUND: Low-risk limits recommended for alcohol consumption vary substantially across different national guidelines. To define thresholds associated with lowest risk for all-cause mortality and cardiovascular disease, we studied individual-participant data from 599 912 current drinkers without......·4 million person-years of follow-up. For all-cause mortality, we recorded a positive and curvilinear association with the level of alcohol consumption, with the minimum mortality risk around or below 100 g per week. Alcohol consumption was roughly linearly associated with a higher risk of stroke (HR per 100...

  15. Detection thresholds of macaque otolith afferents.

    Science.gov (United States)

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

    2012-06-13

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

  16. Análisis multifactorial de los factores de riesgo de bajo peso al nacer en Salvador, Bahia

    Directory of Open Access Journals (Sweden)

    Solla Jorge José Santos Pereira

    1997-01-01

    Full Text Available El presente estudio constituye un análisis multifactorial de los factores de riesgo de bajo peso al nacer en un grupo de recién nacidos en una zona urbana del Brasil. Se incluyeron en el estudio un total de 1 023 nacidos vivos, dados a luz en cuatro maternidades de Salvador, Bahia, entre julio de 1987 y febrero de 1988. Las fuentes de información fueron las historias clínicas y las entrevistas con las madres en la maternidad. El análisis se realizó mediante regresión logística. En el modelo final los factores de riesgo incluidos fueron los siguientes: edad materna menos de 21 años o más de 35; edad gestacional menos de 38 semanas; resultado desfavorable del embarazo anterior; intervalo intergenésico previo de 12 meses o menos; tabaquismo; e hipertensión. Se presentan los valores del riesgo atribuible poblacional para los factores de riesgo incluidos en el modelo final. Esos factores deben emplearse para detectar a las gestantes con alto riesgo de dar a luz un niño de bajo peso, a las que debe brindarse mayor atención prenatal.

  17. Preclinical Evaluation of miR-15/107 Family Members as Multifactorial Drug Targets for Alzheimer's Disease

    Directory of Open Access Journals (Sweden)

    Sepideh Parsi

    2015-01-01

    Full Text Available Alzheimer's disease (AD is a multifactorial, fatal neurodegenerative disorder characterized by the abnormal accumulation of Aβ and Tau deposits in the brain. There is no cure for AD, and failure at different clinical trials emphasizes the need for new treatments. In recent years, significant progress has been made toward the development of miRNA-based therapeutics for human disorders. This study was designed to evaluate the efficiency and potential safety of miRNA replacement therapy in AD, using miR-15/107 paralogues as candidate drug targets. We identified miR-16 as a potent inhibitor of amyloid precursor protein (APP and BACE1 expression, Aβ peptide production, and Tau phosphorylation in cells. Brain delivery of miR-16 mimics in mice resulted in a reduction of AD-related genes APP, BACE1, and Tau in a region-dependent manner. We further identified Nicastrin, a γ-secretase component involved in Aβ generation, as a target of miR-16. Proteomics analysis identified a number of additional putative miR-16 targets in vivo, including α-Synuclein and Transferrin receptor 1. Top-ranking biological networks associated with miR-16 delivery included AD and oxidative stress. Collectively, our data suggest that miR-16 is a good candidate for future drug development by targeting simultaneously endogenous regulators of AD biomarkers (i.e., Aβ and Tau, inflammation, and oxidative stress.

  18. Characterization of Chlorinated Aliphatic Hydrocarbons and Environmental Variables in a Shallow Groundwater in Shanghai Using Kriging Interpolation and Multifactorial Analysis.

    Directory of Open Access Journals (Sweden)

    Qiang Lu

    Full Text Available CAHs, as a cleaning solvent, widely contaminated shallow groundwater with the development of manufacturing in China's Yangtze River Delta. This study focused on the distribution of CAHs, and correlations between CAHs and environmental variables in a shallow groundwater in Shanghai, using kriging interpolation and multifactorial analysis. The results showed that the overall CAHs plume area (above DIV was approximately 9,000 m(2 and located in the 2-4 m underground, DNAPL was accumulated at an area of approximately 1,400 m(2 and located in the 6-8m sandy silt layer on the top of the muddy silty clay. Heatmap of PPC for CAHs and environmental variables showed that the correlation between "Fe(2+" and most CAHs such as "1,1,1-TCA", "1,1-DCA", "1,1-DCE" and "%TCA" were significantly positive (p<0.001, but "%CA" and/or "%VC" was not, and "Cl-" was significantly positive correlated with "1,1-DCA" and "1,1-DCE" (p<0.001. The PCA demonstrated that the relative proportions of CAHs in groundwater were mostly controlled by the sources and the natural attenuation. In conclusion, the combination of geographical and chemometrics was helpful to establishing an aerial perspective of CAHs and identifying reasons for the accumulation of toxic dechlorination intermediates, and could become a useful tool for characterizing contaminated sites in general.

  19. Baryon-antibaryon threshold and ω-baryonium mixing

    International Nuclear Information System (INIS)

    Gavai, R.V.

    1981-01-01

    It is shown that in any dual-topological-unitarization model of ω-baryonium (B) mixing at the cylinder level, in which the production of baryon-antibaryon (bb-bar) pairs can take place only above a certain threshold energy, the phenomenologically relevant ω and B trajectories do not mix below bb-bar threshold. However, their couplings to external particles do get modified. The ω-B mixing angle theta/sub omegahyphenB/, which characterizes these coupling modification effects below bb-bar threshold at t = 0, is estimated in some models. These estimates are found to agree reasonably well with the existing phenomenological bound on theta/sub omegahyphenB/

  20. Relation of the runaway avalanche threshold to momentum space topology

    Science.gov (United States)

    McDevitt, Christopher J.; Guo, Zehua; Tang, Xian-Zhu

    2018-02-01

    The underlying physics responsible for the formation of an avalanche instability due to the generation of secondary electrons is studied. A careful examination of the momentum space topology of the runaway electron population is carried out with an eye toward identifying how qualitative changes in the momentum space of the runaway electrons is correlated with the avalanche threshold. It is found that the avalanche threshold is tied to the merger of an O and X point in the momentum space of the primary runaway electron population. Such a change of the momentum space topology is shown to be accurately described by a simple analytic model, thus providing a powerful means of determining the avalanche threshold for a range of model assumptions.

  1. Analysis of threshold curves for superconducting interferometers

    International Nuclear Information System (INIS)

    Peterson, R.L.; Hamilton, C.A.

    1979-01-01

    Threshold curves for multijunction superconducting interferometers have been calculated previously, showing general agreement with observed features, especially in symmetric cases. We here add some more details to the analysis, paying particular attention to the effects of asymmetries in coupling, inductance, or critical currents. Feed-loop inductance and flux quantization in the feed loop can be important. A changing lobe pattern over many periods, asymmetries within a period, shifting patterns between runs spanning a warm-up, and sudden changes in pattern because of noise in the environment are all quantitatively explainable on the basis of this model. By use of a single ''calibration curve'', the inductance for symmetric two- or three-junction interferometers can be obtained immediately

  2. Deuteron threshold electrodisintegration at high momentum transfer

    International Nuclear Information System (INIS)

    Schmitt, W.M.; Turchinetz, W.; Williamson, C.F.; Yates, T.C.; Zumbro, J.D.; Lee, K.S.; Baghaei, H.; Churchwell, S.; Hicks, R.S.; Miskimen, R.; Peterson, G.A.; Wang, K.; Bosted, P.E.; Spengos, M.; Frois, B.; Martino, J.; Platchkov, S.; Hotta, A.

    1997-01-01

    Absolute differential cross sections for the threshold electrodisintegration of the deuteron with good resolution were measured at a laboratory scattering angle of 160 degree for five values of Q 2 ranging from 8.66 to 42.4fm -2 . Comparisons of the data averaged over E np from 0 to 3 MeV and from 0 to 10 MeV are made with nonrelativistic meson exchange calculations. These calculations are sensitive to the nucleon electromagnetic form factors, nucleon-nucleon potential, and relativistic effects. The data are also compared with a hybrid quark-hadron model calculation that describes the deuteron as a six-quark cluster for the short range part of the interaction. Some of these calculations can describe the data reasonably well over certain ranges of Q 2 ; however, none of these calculations can accurately describe the data over the entire measured Q 2 range. copyright 1997 The American Physical Society

  3. Deuteron threshold electrodisintegration at high momentum transfer

    International Nuclear Information System (INIS)

    Schmitt, W.M.; Turchinetz, W.; Williamson, C.F.

    1997-01-01

    Absolute differential cross sections for the threshold electrodisintegration of the deuteron with good resolution were measured at a laboratory scattering angle of 160 degree for five values of Q 2 ranging from 8.66 to 42.4 fm -2 . Comparisons of the data averaged over E np from 0--3 MeV and 0--10 MeV are made with nonrelativistic meson-exchange calculations. These calculations are sensitive to the nucleon electromagnetic form factors, nucleon-nucleon potential, and relativistic effects. The data are also compared with a hybrid quark-hadron model calculation that describes the deuteron as a six-quark cluster for the short range part of the interaction. Some of these calculations can describe the data reasonably well over certain ranges of Q 2 ; however, none of these calculations can accurately describe the data over the entire measured Q 2 range

  4. Multifactorial Causes of Suicide

    Directory of Open Access Journals (Sweden)

    Antemir Cristina-Laura

    2017-12-01

    Full Text Available The science of psychology is well placed to the advantage of understanding why some people are trying to take their lives, and others do not. Understanding the psychological processes underlying the idea of suicide and the decision to act on suicidal thoughts is particularly important. Especially since interventions should be targeted at the suicidal ideation when it first appears before it becomes an attempt of suicide. Factors associated with suicidal risk can be classified into four groups: personality and individual differences, cognitive factors, social factors and life-threatening factors. Each of these factors can contribute to the emergence of suicide risk independently or together with other factors. Some of them are associated with the emergence of suicidal ideation, while others increase the likelihood that these thoughts will come to life.

  5. Spike-threshold adaptation predicted by membrane potential dynamics in vivo.

    Directory of Open Access Journals (Sweden)

    Bertrand Fontaine

    2014-04-01

    Full Text Available Neurons encode information in sequences of spikes, which are triggered when their membrane potential crosses a threshold. In vivo, the spiking threshold displays large variability suggesting that threshold dynamics have a profound influence on how the combined input of a neuron is encoded in the spiking. Threshold variability could be explained by adaptation to the membrane potential. However, it could also be the case that most threshold variability reflects noise and processes other than threshold adaptation. Here, we investigated threshold variation in auditory neurons responses recorded in vivo in barn owls. We found that spike threshold is quantitatively predicted by a model in which the threshold adapts, tracking the membrane potential at a short timescale. As a result, in these neurons, slow voltage fluctuations do not contribute to spiking because they are filtered by threshold adaptation. More importantly, these neurons can only respond to input spikes arriving together on a millisecond timescale. These results demonstrate that fast adaptation to the membrane potential captures spike threshold variability in vivo.

  6. Quantifying the Arousal Threshold Using Polysomnography in Obstructive Sleep Apnea.

    Science.gov (United States)

    Sands, Scott A; Terrill, Philip I; Edwards, Bradley A; Taranto Montemurro, Luigi; Azarbarzin, Ali; Marques, Melania; de Melo, Camila M; Loring, Stephen H; Butler, James P; White, David P; Wellman, Andrew

    2018-01-01

    Precision medicine for obstructive sleep apnea (OSA) requires noninvasive estimates of each patient's pathophysiological "traits." Here, we provide the first automated technique to quantify the respiratory arousal threshold-defined as the level of ventilatory drive triggering arousal from sleep-using diagnostic polysomnographic signals in patients with OSA. Ventilatory drive preceding clinically scored arousals was estimated from polysomnographic studies by fitting a respiratory control model (Terrill et al.) to the pattern of ventilation during spontaneous respiratory events. Conceptually, the magnitude of the airflow signal immediately after arousal onset reveals information on the underlying ventilatory drive that triggered the arousal. Polysomnographic arousal threshold measures were compared with gold standard values taken from esophageal pressure and intraoesophageal diaphragm electromyography recorded simultaneously (N = 29). Comparisons were also made to arousal threshold measures using continuous positive airway pressure (CPAP) dial-downs (N = 28). The validity of using (linearized) nasal pressure rather than pneumotachograph ventilation was also assessed (N = 11). Polysomnographic arousal threshold values were correlated with those measured using esophageal pressure and diaphragm EMG (R = 0.79, p < .0001; R = 0.73, p = .0001), as well as CPAP manipulation (R = 0.73, p < .0001). Arousal threshold estimates were similar using nasal pressure and pneumotachograph ventilation (R = 0.96, p < .0001). The arousal threshold in patients with OSA can be estimated using polysomnographic signals and may enable more personalized therapeutic interventions for patients with a low arousal threshold. © Sleep Research Society 2017. Published by Oxford University Press on behalf of the Sleep Research Society. All rights reserved. For permissions, please e-mail journals.permissions@oup.com.

  7. A numerical study of threshold states

    International Nuclear Information System (INIS)

    Ata, M.S.; Grama, C.; Grama, N.; Hategan, C.

    1979-01-01

    There are some experimental evidences of charged particle threshold states. On the statistical background of levels, some simple structures were observed in excitation spectrum. They occur near the coulombian threshold and have a large reduced width for the decay in the threshold channel. These states were identified as charged cluster threshold states. Such threshold states were observed in sup(15,16,17,18)O, sup(18,19)F, sup(19,20)Ne, sup(24)Mg, sup(32)S. The types of clusters involved were d, t, 3 He, α and even 12 C. They were observed in heavy-ions transfer reactions in the residual nucleus as strong excited levels. The charged particle threshold states occur as simple structures at high excitation energy. They could be interesting both from nuclear structure as well as nuclear reaction mechanism point of view. They could be excited as simple structures both in compound and residual nucleus. (author)

  8. Iran: the next nuclear threshold state?

    OpenAIRE

    Maurer, Christopher L.

    2014-01-01

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

  9. Dynamical thresholds for complete fusion

    International Nuclear Information System (INIS)

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

    1983-01-01

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

  10. Stochastic Calculus: Application to Dynamic Bifurcations and Threshold Crossings

    Science.gov (United States)

    Jansons, Kalvis M.; Lythe, G. D.

    1998-01-01

    For the dynamic pitchfork bifurcation in the presence of white noise, the statistics of the last time at zero are calculated as a function of the noise level ∈ and the rate of change of the parameter μ. The threshold crossing problem used, for example, to model the firing of a single cortical neuron is considered, concentrating on quantities that may be experimentally measurable but have so far received little attention. Expressions for the statistics of pre-threshold excursions, occupation density, and last crossing time of zero are compared with results from numerical generation of paths.

  11. Cytotoxicity of anthraquinones from the roots of Pentas schimperi towards multi-factorial drug-resistant cancer cells.

    Science.gov (United States)

    Kuete, Victor; Donfack, Arno R Nanfack; Mbaveng, Armelle T; Zeino, Maen; Tane, Pierre; Efferth, Thomas

    2015-08-01

    Multidrug resistance in cancer represents a major problem in chemotherapy. The present study was designed to assess the cytotoxicity of anthraquinones from Pentas schimperi, namely damnacanthal (1), damnacanthol (2), 3-hydroxy-2-hydroxymethyl anthraquinone (3) and schimperiquinone B (4) against nine drug-sensitive and multidrug resistant (MDR) cancer cell lines. The resazurin reduction assay was used to evaluate the cytotoxicity of the above compounds, whilst caspase-Glo assay was used to detect the activation of caspases enzymes by compounds 1 and 2. Cell cycle, mitochondrial membrane potential (MMP) and levels of reactive oxygen species were all analyzed via flow cytometry. Anthraquinones 1 and 2 displayed cytotoxic effects with IC50 values below 81 μM on all the nine tested cancer cell lines whilst 3 and 4 displayed selective activities. The recorded IC50 values for compounds 1 and 2 ranged from 3.12 μM and 12.18 μM (towards leukemia CCRF-CEM cells) and from 30.32 μM and 80.11 μM (towards gliobastoma U87MG.ΔEGFR cells) respectively, and from 0.20 μM (against CCRF-CEM cells) to 195.12 μM (against CEM/ADR5000 cells) for doxorubicin. Compounds 1 and 2 induced apoptosis in CCRF-CEM leukemia cells, mediated by the disruption of the MMP and increase in ROS production. Anthraquinones from Pentas schimperi and mostly 1 and 2 are potential cytotoxic natural products that deserve more investigations to develop novel antineoplastic drugs against multifactorial drug resistant cancers.

  12. Threshold Studies of the Microwave Instability in Electron Storage Rings

    International Nuclear Information System (INIS)

    Bane, Karl

    2010-01-01

    We use a Vlasov-Fokker-Planck program and a linearized Vlasov solver to study the microwave instability threshold of impedance models: (1) a Q = 1 resonator and (2) shielded coherent synchrotron radiation (CSR), and find the results of the two programs agree well. For shielded CSR we show that only two dimensionless parameters, the shielding parameter Π and the strength parameter S csr , are needed to describe the system. We further show that there is a strong instability associated with CSR, and that the threshold, to good approximation, is given by (S csr )th = 0.5 + 0.12Π. In particular, this means that shielding has little effect in stabilizing the beam for Π ∼ -3/2 . We, in addition, find another instability in the vicinity of Π = 0.7 with a lower threshold, (S csr ) th ∼ 0.2. We find that the threshold to this instability depends strongly on damping time, (S csr ) th ∼ τ p -1/2 , and that the tune spread at threshold is small - both hallmarks of a weak instability.

  13. Comparison of memory thresholds for planar qudit geometries

    Science.gov (United States)

    Marks, Jacob; Jochym-O'Connor, Tomas; Gheorghiu, Vlad

    2017-11-01

    We introduce and analyze a new type of decoding algorithm called general color clustering, based on renormalization group methods, to be used in qudit color codes. The performance of this decoder is analyzed under a generalized bit-flip error model, and is used to obtain the first memory threshold estimates for qudit 6-6-6 color codes. The proposed decoder is compared with similar decoding schemes for qudit surface codes as well as the current leading qubit decoders for both sets of codes. We find that, as with surface codes, clustering performs sub-optimally for qubit color codes, giving a threshold of 5.6 % compared to the 8.0 % obtained through surface projection decoding methods. However, the threshold rate increases by up to 112% for large qudit dimensions, plateauing around 11.9 % . All the analysis is performed using QTop, a new open-source software for simulating and visualizing topological quantum error correcting codes.

  14. Fusion of Thresholding Rules During Wavelet-Based Noisy Image Compression

    Directory of Open Access Journals (Sweden)

    Bekhtin Yury

    2016-01-01

    Full Text Available The new method for combining semisoft thresholding rules during wavelet-based data compression of images with multiplicative noise is suggested. The method chooses the best thresholding rule and the threshold value using the proposed criteria which provide the best nonlinear approximations and take into consideration errors of quantization. The results of computer modeling have shown that the suggested method provides relatively good image quality after restoration in the sense of some criteria such as PSNR, SSIM, etc.

  15. Raison d’être of insulin resistance: the adjustable threshold hypothesis

    OpenAIRE

    Wang, Guanyu

    2014-01-01

    The epidemics of obesity and diabetes demand a deeper understanding of insulin resistance, for which the adjustable threshold hypothesis is formed in this paper. To test the hypothesis, mathematical modelling was used to analyse clinical data and to simulate biological processes at both molecular and organismal levels. I found that insulin resistance roots in the thresholds of the cell's bistable response. By assuming heterogeneity of the thresholds, single cells' all-or-none response can col...

  16. Mouse models for atherosclerosis and pharmaceutical modifiers

    NARCIS (Netherlands)

    Zadelaar, A.S.M.; Kleemann, R.; Verschuren, L.; Vries-van der Weij, J. de; Hoorn, J. van der; Princen, H.M.; Kooistra, T.

    2007-01-01

    Atherosclerosis is a multifactorial highly-complex disease with numerous etiologies that work synergistically to promote lesion development. The ability to develop preventive and ameliorative treatments will depend on animal models that mimic the human subject metabolically and pathophysiologically

  17. Baseline and follow-up characteristics of participants and nonparticipants in a randomized clinical trial of multifactorial fall prevention in Denmark

    DEFF Research Database (Denmark)

    Vind, Ane B; Andersen, Hanne E; Pedersen, Kirsten D

    2009-01-01

    outpatient department. PARTICIPANTS: One thousand one hundred five community-dwelling adults aged 65 and older who had sustained at least one injurious fall. MEASUREMENTS: Marital status, housing tenure, income, comorbidity, hospitalization, fractures, and drug use before invitation to participate......OBJECTIVES: To address the external validity of a trial of multifactorial fall prevention through an analysis of differences between participants and nonparticipants regarding socioeconomic and morbidity variables. DESIGN: Analysis of nonresponse in a randomized clinical trial. SETTING: Geriatric...... nonparticipants of a trial of multifactorial fall prevention differed significantly from participants in terms of socioeconomic and morbidity variables and were more likely to be hospitalized or die during 6 months of follow-up. Because of the differences between the two populations, it is questionable whether...

  18. What works better for community-dwelling older people at risk to fall?: a meta-analysis of multifactorial versus physical exercise-alone interventions.

    Science.gov (United States)

    Petridou, Eleni Th; Manti, Eirini G; Ntinapogias, Athanasios G; Negri, Eva; Szczerbinska, Katarzyna

    2009-08-01

    To compare and quantify the effectiveness of multifactorial versus exercise-alone interventions in reducing recurrent falls among community-dwelling older people. A meta-analysis of recently published studies on fall prevention interventions was conducted. Measure of the overall effectiveness was the combined risk ratio for recurrent falls, whereas heterogeneity was explored via metaregression analyses. Ten of the 52 identified studies met the preset criteria and were included in the analysis. The exercise-alone interventions were about 5 times more effective compared to multifactorial ones. Short-term interventions, smaller samples, and younger age related to better outcomes. From cost-efficiency and public health perspectives, exercise-alone interventions can be considered valuable, as they are more likely to be implemented in countries with less resources. Further qualitative research is needed, however, to explore determinants of willingness to participate and comply with interventions aiming to prevent recurrent falls among older people.

  19. The asymmetry of U.S. monetary policy: Evidence from a threshold Taylor rule with time-varying threshold values

    Science.gov (United States)

    Zhu, Yanli; Chen, Haiqiang

    2017-05-01

    In this paper, we revisit the issue whether U.S. monetary policy is asymmetric by estimating a forward-looking threshold Taylor rule with quarterly data from 1955 to 2015. In order to capture the potential heterogeneity for regime shift mechanism under different economic conditions, we modify the threshold model by assuming the threshold value as a latent variable following an autoregressive (AR) dynamic process. We use the unemployment rate as the threshold variable and separate the sample into two periods: expansion periods and recession periods. Our findings support that the U.S. monetary policy operations are asymmetric in these two regimes. More precisely, the monetary authority tends to implement an active Taylor rule with a weaker response to the inflation gap (the deviation of inflation from its target) and a stronger response to the output gap (the deviation of output from its potential level) in recession periods. The threshold value, interpreted as the targeted unemployment rate of monetary authorities, exhibits significant time-varying properties, confirming the conjecture that policy makers may adjust their reference point for the unemployment rate accordingly to reflect their attitude on the health of general economy.

  20. A Multifactorial Intervention Based on the NICE-Adjusted Guideline in the Prevention of Delirium in Patients Hospitalized for Cardiac Surgery

    Directory of Open Access Journals (Sweden)

    Mohammad Ali Cheraghi

    2017-05-01

    Full Text Available Delirium is the most common problem in patients in intensive care units. Prevention of delirium is more important than treatment. The aim of this study is to determine the effect of the NICE-adjusted multifactorial intervention to prevent delirium in open heart surgery patients. Methods: This study is a quasi-experimental study on 88 patients (In each group, 44 patients undergoing open heart surgery in the intensive care unit of Imam Khomeini Hospital, Tehran. Subjects received usual care group, only the incidence of delirium were studied. So that patients in the two groups of second to fifth postoperative day, twice a day by the researcher, and CAM-ICU questionnaire were followed. After completion of the sampling in this group, in the intervention group also examined incidence of delirium was conducted in the same manner except that multifactorial interventions based on the intervention of NICE modified by the researcher on the second day to fifth implementation and intervention on each turn, their implementation was followed. As well as to check the quality of sleep and pain in the intervention group of CPOT and Pittsburgh Sleep assessment tools were used. Data analysis was done using the SPSS software, version 16. A T-test, a chi-square test, and a Fisher’s exact test were also carried out. Results: The incidence of delirium in the control group was 42.5%; and in the intervention group, it was 22.5%. The result showed the incidence of delirium in open heart surgery hospitalized patients after multifactorial intervention based on adjusted NICE guidelines has been significantly reduced. Conclusion: The NICE-adjusted multifactorial intervention guidelines for the prevention of delirium in cardiac surgery patients significantly reduced the incidence of delirium in these patients. So, using this method as an alternative comprehensive and reliable in preventing delirium in hospitalized patients in the ward heart surgery is recommended.