Sobral, Maria P.; Costa, Maria E.; Schmidt, Lone
2017-01-01
comparability of fertility-related stress across genders and countries. STUDY DESIGN SIZE, DURATION Cross-sectional study. First, we tested the structure of the COMPI-FPSS. Then, reliability and validity (convergent and discriminant) were examined for the final model. Finally, measurement invariance both across......STUDY QUESTION Are the Copenhagen Multi‐Centre Psychosocial Infertility research program Fertility Problem Stress Scales (COMPI-FPSS) a reliable and valid measure across gender and culture? SUMMARY ANSWER The COMPI-FPSS is a valid and reliable measure, presenting excellent or good fit...... in the majority of the analyzed countries, and demonstrating full invariance across genders and partial invariance across cultures. WHAT IS KNOWN ALREADY Cross-cultural and gender validation is needed to consider a measure as standard care within fertility. The present study is the first attempting to establish...
Remote sensing and vegetation stress detection - Problems and progress
Duggin, M. J.; Whitehead, V.
1983-01-01
Although considerable progress has been made in applying remote sensing technology to vegetation monitoring, considerable problems still exist in the improvement of techniques for crop type discrimination, stress detection on a large scale, and stress quantification. In this paper, some of the problems remaining in the operational use of remote sensing technology for vegetation stress detection are discussed, and directions in which some of these problems might be solved are proposed.
Effects of community stress and problems on residents' psychopathology.
Zhou, Rui; Zhang, Jie
2014-02-28
The connection between community stress and problems and community residents' psychopathology is an understudied area, and a limited number of studies have reported inconsistent findings. This research aimed to estimate the effect of perceived social factors in the community environment on the residents' self-reported psychopathology. The study sample consisted of 2034 men and women from 16 selected rural counties in three provinces of China. The social factors in the village community were measured by the World Health Organization Multisite Intervention Study on Suicidal Behaviors (WHO SUPRE-MISS) scale of Community Stress and Problems. The sychological and mental health of the individuals was assessed by (1) suicidal thoughts, plans and attempts (National Comorbidity Survey Replication or NCS-R), (2) pro-suicide attitudes (General Social Survey or GSS), (3) depression (Center for Epidemiological Studies Depression Scale or CES-D) and (4) suicide ideation (Scale for Suicide Ideation or SSI). Multiple regressions were performed separately for each of the four psychopathologic traits with the scale of Community Stress and Problems as the major predicting variable and age, gender, education years, marital status, family annual income, family status in village and religion as the confounding correlates. It is found that community stress and problems generally increase rural Chinese residents' psychopathologies, especially issues in health care, housing and transportation, which play more important roles than others. © 2013 Elsevier Ireland Ltd. All rights reserved.
Psychometric Validation of Stress and Compliance Scale for ...
Keywords: Diabetes mellitus, Malaysia stress scale, Stress and compliance scale for diabetes, Stress, ... International Pharmaceutical Abstract, Chemical Abstracts, Embase, Index Copernicus, .... also, the researcher and co-researchers.
[Stress and allostasis: problems, outlooks and relationships].
Kupriianov, R V; Zhdanov, R I
2014-01-01
Concepts of stress and allostasis are discussed in the paper in their interrelation and interpenetration. General adaptation syndrome is considered in the historical aspect of Claude Bernard's, William Cannon's and Hans Selye's contributions to the field, and from the standpoint of an interdisciplinary approach. Key challenges and contradictions of the stress concept are disclosed and discussed. First, the terminology ones, since this term might be understood as stress response, stressor, state of the organism and even the consequences of stress itself. Second, it is ambivalent and contradictory nature of the stress response. From the perception of stress as a reaction to the strong negative impact of environment, researchers became to divide stress onto two types: distress as a non-specific basis of disease, and eustress as a favorable factor that extends the adaptability of human organism. The third problem is connected to the interdisciplinary nature of the stress response, the effects of which being manifested in, at least, four areas: physiology, behavior, subjective experience, and cognitive functions. Particularily, physiologists are very often ignored of a role of cognitive factors in their stress research. The authors in terms of the allostasis theory, more complex adaptation process than homeostasis, resolve contradictories of stress conception observed. The paper proposes a model of allostatic states to describe distress and eustress phenomena.
Sensitivity analysis for large-scale problems
Noor, Ahmed K.; Whitworth, Sandra L.
1987-01-01
The development of efficient techniques for calculating sensitivity derivatives is studied. The objective is to present a computational procedure for calculating sensitivity derivatives as part of performing structural reanalysis for large-scale problems. The scope is limited to framed type structures. Both linear static analysis and free-vibration eigenvalue problems are considered.
Scaling of Attitudes Toward Population Problems
Watkins, George A.
1975-01-01
This study related population problem attitudes and socioeconomic variables. Six items concerned with number of children, birth control, family, science, economic depression, and overpopulation were selected for a Guttman scalogram. Education, occupation, and number of children were correlated with population problems scale scores; marital status,…
Scaling of Attitudes Toward Population Problems
Watkins, George A.
1975-01-01
This study related population problem attitudes and socioeconomic variables. Six items concerned with number of children, birth control, family, science, economic depression, and overpopulation were selected for a Guttman scalogram. Education, occupation, and number of children were correlated with population problems scale scores; marital status,…
Ensemble methods for large scale inverse problems
Heemink, A.W.; Umer Altaf, M.; Barbu, A.L.; Verlaan, M.
2013-01-01
Variational data assimilation, also sometimes simply called the ‘adjoint method’, is used very often for large scale model calibration problems. Using the available data, the uncertain parameters in the model are identified by minimizing a certain cost function that measures the difference between t
Perceived Problem Solving, Stress, and Health among College Students
Largo-Wight, Erin; Peterson, P. Michael; Chen, W. William
2005-01-01
Objective: To study the relationships among perceived problem solving, stress, and physical health. Methods: The Perceived Stress Questionnaire (PSQ), Personal Problem solving Inventory (PSI), and a stress-related physical health symptoms checklist were used to measure perceived stress, problem solving, and health among undergraduate college…
Periodic cells for large-scale problem initialization
Ciantia, Matteo O.; Arroyo, Marcos; Zhang, Ningning; Emam, Sacha
2017-06-01
In geotechnical applications the success of the discrete element method (DEM) in simulating fundamental aspects of soil behaviour has increased the interest in applications for direct simulation of engineering scale boundary value problems (BVP's). The main problem is that the method remains relatively expensive in terms of computational cost. A non-negligible part of that cost is related to specimen creation and initialization. As the response of soil is strongly dependant on its initial state (stress and porosity), attaining a specified initial state is a crucial part of a DEM model. Different procedures for controlled sample generation are available. However, applying the existing REV-oriented initialization procedures to such models is inefficient in terms of computational cost and challenging in terms of sample homogeneity. In this work a simple but efficient procedure to initialize large-scale DEM models is presented. Periodic cells are first generated with a sufficient number of particles matching a desired particle size distribution (PSD). The cells are then equilibrated at low-level isotropic stress at target porosity. Once the cell is in equilibrium, it is replicated in space in order to fill the model domain. After the domain is thus filled a few mechanical cycles are needed to re-equilibrate the large domain. The result is a large, homogeneous sample, equilibrated under prescribed stress at the desired porosity. The method is applicable to both isotropic and anisotropic initial stress states, with stress magnitude varying in space.
Stabilization Algorithms for Large-Scale Problems
Jensen, Toke Koldborg
2006-01-01
The focus of the project is on stabilization of large-scale inverse problems where structured models and iterative algorithms are necessary for computing approximate solutions. For this purpose, we study various iterative Krylov methods and their abilities to produce regularized solutions. Some......-curve. This heuristic is implemented as a part of a larger algorithm which is developed in collaboration with G. Rodriguez and P. C. Hansen. Last, but not least, a large part of the project has, in different ways, revolved around the object-oriented Matlab toolbox MOORe Tools developed by PhD Michael Jacobsen. New...
Self-Affirmation Improves Problem-Solving under Stress
J. David Creswell; Dutcher, Janine M.; Klein, William M.P.; Harris, Peter R; Levine, John M.
2013-01-01
High levels of acute and chronic stress are known to impair problem-solving and creativity on a broad range of tasks. Despite this evidence, we know little about protective factors for mitigating the deleterious effects of stress on problem-solving. Building on previous research showing that self-affirmation can buffer stress, we tested whether an experimental manipulation of self-affirmation improves problem-solving performance in chronically stressed participants. Eighty undergraduates indi...
Self-affirmation improves problem-solving under stress.
Creswell, J David; Dutcher, Janine M; Klein, William M P; Harris, Peter R; Levine, John M
2013-01-01
High levels of acute and chronic stress are known to impair problem-solving and creativity on a broad range of tasks. Despite this evidence, we know little about protective factors for mitigating the deleterious effects of stress on problem-solving. Building on previous research showing that self-affirmation can buffer stress, we tested whether an experimental manipulation of self-affirmation improves problem-solving performance in chronically stressed participants. Eighty undergraduates indicated their perceived chronic stress over the previous month and were randomly assigned to either a self-affirmation or control condition. They then completed 30 difficult remote associate problem-solving items under time pressure in front of an evaluator. Results showed that self-affirmation improved problem-solving performance in underperforming chronically stressed individuals. This research suggests a novel means for boosting problem-solving under stress and may have important implications for understanding how self-affirmation boosts academic achievement in school settings.
Psychometric Validation of Stress and Compliance Scale for ...
Tropical Journal of Pharmaceutical Research ... Method: A population-based survey was conducted in Penang, Malaysia during Nov 2012 to March 2013. ... Keywords: Diabetes mellitus, Malaysia stress scale, Stress and compliance scale for ...
Mindfulness and Alcohol Problems in College Students: The Mediating Effects of Stress
Bodenlos, Jamie S.; Noonan, Marleah; Wells, Stephanie Y.
2013-01-01
Objective: To examine the relationship between mindfulness and alcohol problems in college students, as well as the role of stress as a mediator in this relationship. Participants: Participants were 310 students from a small, private college in the Northeast. Methods: Students completed self-report measures, including the Perceived Stress Scale,…
Mindfulness and Alcohol Problems in College Students: The Mediating Effects of Stress
Bodenlos, Jamie S.; Noonan, Marleah; Wells, Stephanie Y.
2013-01-01
Objective: To examine the relationship between mindfulness and alcohol problems in college students, as well as the role of stress as a mediator in this relationship. Participants: Participants were 310 students from a small, private college in the Northeast. Methods: Students completed self-report measures, including the Perceived Stress Scale,…
Lyu, Juncheng; Shi, Hong; Wang, Suzhen; Zhang, Jie
2016-02-01
This research aimed to estimate the effect of perceived social factors in the community stress and problems on the residents' psychopathology such as depression and suicidal behaviors. Subjects of this study were the informants (N=1618) in a psychological autopsy (PA) study with a case-control design. We interviewed two informants (a family member and a close friend) for 392 suicides and 416 living controls, which came from 16 rural counties randomly selected from three provinces of China. Community stress and problems were measured by the WHO SUPRE-MISS scale. Depression was measured by CES-D scale, and suicidal behavior was assessed by NCS-R scale. Multivariable liner and logistic regression models and the Structural Equation Modeling (SEM) were applied to probe the correlation of the depression and the suicidal behaviors with some major demographic variables as covariates. It was found that community stress and problems were directly associated with rural Chinese residents' depression (Path coefficient=0.127, Pstress and problem and suicidal behaviors, but community stress and problem can affect suicidal behaviors indirectly through depression. The path coefficient between depression and suicidal behaviors was 0.975. The current study predicts a new research viewpoint, that is, the depression is the intermediate between community stress and problem and suicidal behaviors. It might be an effective route to prevent depression directly and suicidal behaviors indirectly by reducing the community stress and problems.
Problem-Solving: Scaling the "Brick Wall"
Benson, Dave
2011-01-01
Across the primary and secondary phases, pupils are encouraged to use and apply their knowledge, skills, and understanding of mathematics to solve problems in a variety of forms, ranging from single-stage word problems to the challenge of extended rich tasks. Amongst many others, Cockcroft (1982) emphasised the importance and relevance of…
Self-affirmation improves problem-solving under stress.
J David Creswell
Full Text Available High levels of acute and chronic stress are known to impair problem-solving and creativity on a broad range of tasks. Despite this evidence, we know little about protective factors for mitigating the deleterious effects of stress on problem-solving. Building on previous research showing that self-affirmation can buffer stress, we tested whether an experimental manipulation of self-affirmation improves problem-solving performance in chronically stressed participants. Eighty undergraduates indicated their perceived chronic stress over the previous month and were randomly assigned to either a self-affirmation or control condition. They then completed 30 difficult remote associate problem-solving items under time pressure in front of an evaluator. Results showed that self-affirmation improved problem-solving performance in underperforming chronically stressed individuals. This research suggests a novel means for boosting problem-solving under stress and may have important implications for understanding how self-affirmation boosts academic achievement in school settings.
Self-Affirmation Improves Problem-Solving under Stress
Creswell, J. David; Dutcher, Janine M.; Klein, William M. P.; Harris, Peter R.; Levine, John M.
2013-01-01
High levels of acute and chronic stress are known to impair problem-solving and creativity on a broad range of tasks. Despite this evidence, we know little about protective factors for mitigating the deleterious effects of stress on problem-solving. Building on previous research showing that self-affirmation can buffer stress, we tested whether an experimental manipulation of self-affirmation improves problem-solving performance in chronically stressed participants. Eighty undergraduates indicated their perceived chronic stress over the previous month and were randomly assigned to either a self-affirmation or control condition. They then completed 30 difficult remote associate problem-solving items under time pressure in front of an evaluator. Results showed that self-affirmation improved problem-solving performance in underperforming chronically stressed individuals. This research suggests a novel means for boosting problem-solving under stress and may have important implications for understanding how self-affirmation boosts academic achievement in school settings. PMID:23658751
Biological Scaling Problems and Solutions in Amphibians.
Levy, Daniel L; Heald, Rebecca
2015-08-10
Size is a primary feature of biological systems that varies at many levels, from the organism to its constituent cells and subcellular structures. Amphibians populate some of the extremes in biological size and have provided insight into scaling mechanisms, upper and lower size limits, and their physiological significance. Body size variation is a widespread evolutionary tactic among amphibians, with miniaturization frequently correlating with direct development that occurs without a tadpole stage. The large genomes of salamanders lead to large cell sizes that necessitate developmental modification and morphological simplification. Amphibian extremes at the cellular level have provided insight into mechanisms that accommodate cell-size differences. Finally, how organelles scale to cell size between species and during development has been investigated at the molecular level, because subcellular scaling can be recapitulated using Xenopus in vitro systems.
Problem-solving skills and hardiness as protective factors against stress in Iranian nurses.
Abdollahi, Abbas; Talib, Mansor Abu; Yaacob, Siti Nor; Ismail, Zanariah
2014-02-01
Nursing is a stressful occupation, even when compared with other health professions; therefore, it is necessary to advance our knowledge about the protective factors that can help reduce stress among nurses. The present study sought to investigate the associations among problem-solving skills and hardiness with perceived stress in nurses. The participants, 252 nurses from six private hospitals in Tehran, completed the Personal Views Survey, the Perceived Stress Scale, and the Problem-Solving Inventory. Structural Equation Modeling (SEM) was used to analyse the data and answer the research hypotheses. As expected, greater hardiness was associated with low levels of perceived stress, and nurses low in perceived stress were more likely to be considered approachable, have a style that relied on their own sense of internal personal control, and demonstrate effective problem-solving confidence. These findings reinforce the importance of hardiness and problem-solving skills as protective factors against perceived stress among nurses, and could be important in training future nurses so that hardiness ability and problem-solving skills can be imparted, allowing nurses to have more ability to control their perceived stress.
Crisis Intervener Perceptions of the Stressfulness of Caller Problems.
McCarthy, Patricia R.; Reese, Robin G.
The importance of volunteers in the provision of mental health crisis intervention services has been well documented. However, the volunteer turn-over rate is quite high, due to factors such as burnout. This study examined stressfulness in relationship to caller problems, as well as variables related to perceptions of stress. In this study…
Scale Problems in Geometric-Kinematic Modelling of Geological Objects
Siehl, Agemar; Thomsen, Andreas
To reveal, to render and to handle complex geological objects and their history of structural development, appropriate geometric models have to be designed. Geological maps, sections, sketches of strain and stress patterns are such well-known analogous two-dimensional models. Normally, the set of observations and measurements supporting them is small in relation to the complexity of the real objects they derive from. Therefore, modelling needs guidance by additional expert knowledge to bridge empty spaces which are not supported by data. Generating digital models of geological objects has some substantial advantages compared to conventional methods, especially if they are supported by an efficient database management system. Consistent 3D models of some complexity can be created, and experiments with time-dependent geological geometries may help to restore coherent sequences of paleogeological states. In order to cope with the problems arising from the combined usage of 3D-geometry models of different scale and resolution within an information system on subsurface geology, geometrical objects need to be annotated with information on the context, within which the geometry model has been established and within which it is valid, and methods supporting storage and retrieval as well as manipulation of geometry at different scales must also take into account and handle such context information to achieve meaningful results. An example is given of a detailed structural study of an open pit lignite mine in the Lower Rhine Basin.
Problem-solving Model for Managing Stress and Anxiety
Taghi Abutalebi Ahmadi
2013-01-01
The purpose of this study is to take a look at problem-solving model for managing stress and anxiety. If each of us as a human being has an organized method for solving the different problems of our life, at that time we can get along with stress and anxiety easily. The capability of problem solving makes it possible for that person a) to distinguish emotions in himself and others b) to understand how excitement affects behavior c) to be able to show different reactions to different emotions....
A study of MLFMA for large-scale scattering problems
Hastriter, Michael Larkin
This research is centered in computational electromagnetics with a focus on solving large-scale problems accurately in a timely fashion using first principle physics. Error control of the translation operator in 3-D is shown. A parallel implementation of the multilevel fast multipole algorithm (MLFMA) was studied as far as parallel efficiency and scaling. The large-scale scattering program (LSSP), based on the ScaleME library, was used to solve ultra-large-scale problems including a 200lambda sphere with 20 million unknowns. As these large-scale problems were solved, techniques were developed to accurately estimate the memory requirements. Careful memory management is needed in order to solve these massive problems. The study of MLFMA in large-scale problems revealed significant errors that stemmed from inconsistencies in constants used by different parts of the algorithm. These were fixed to produce the most accurate data possible for large-scale surface scattering problems. Data was calculated on a missile-like target using both high frequency methods and MLFMA. This data was compared and analyzed to determine possible strategies to increase data acquisition speed and accuracy through multiple computation method hybridization.
Large-Scale Inverse Problems and Quantification of Uncertainty
Biegler, Lorenz; Ghattas, Omar
2010-01-01
Large-scale inverse problems and associated uncertainty quantification has become an important area of research, central to a wide range of science and engineering applications. Written by leading experts in the field, Large-scale Inverse Problems and Quantification of Uncertainty focuses on the computational methods used to analyze and simulate inverse problems. The text provides PhD students, researchers, advanced undergraduate students, and engineering practitioners with the perspectives of researchers in areas of inverse problems and data assimilation, ranging from statistics and large-sca
Topology Optimization of Large Scale Stokes Flow Problems
Aage, Niels; Poulsen, Thomas Harpsøe; Gersborg-Hansen, Allan
2008-01-01
This note considers topology optimization of large scale 2D and 3D Stokes flow problems using parallel computations. We solve problems with up to 1.125.000 elements in 2D and 128.000 elements in 3D on a shared memory computer consisting of Sun UltraSparc IV CPUs.......This note considers topology optimization of large scale 2D and 3D Stokes flow problems using parallel computations. We solve problems with up to 1.125.000 elements in 2D and 128.000 elements in 3D on a shared memory computer consisting of Sun UltraSparc IV CPUs....
A biorthogonality relationship for three-dimensional couple stress problem
LUO JianHui; LI QiuSheng; LIU GuangDong
2009-01-01
The duality solution for elasticity and the biorthogonality relationship have been well researched. Now the couple stress theory becomes a new research spot but there is few research for the biorthogonality relationship for couple stress theory comparing to classical elasticity. A new state vector is presented for three dimensional couple stress problems of prismatic structures. A new biorthogonality relation-ship of couple stress is discovered. The dual partial differential equations of couple stress problem are derived by the new state vector. By two important identical equations the new biorthogonality rela-tionship is proved based on the method of separation of variables. The symplectic orthogonality rela-tionship to three dimensional couple stress theory may be decomposed into two independently and symmetrically orthogonality relationships. The new biorthogonality relationship includes the symplectic orthogonality relationship. The biorthogonality relationship of couple stress may also be degenerated into the theory of elasticity. The new state vector and biorthogonality relationship provide theoretic foundation for the research on the schemes of separation of variables and eigenfunction expansion of couple stress theory.
A biorthogonality relationship for three-dimensional couple stress problem
无
2009-01-01
The duality solution for elasticity and the biorthogonality relationship have been well researched. Now the couple stress theory becomes a new research spot but there is few research for the biorthogonality relationship for couple stress theory comparing to classical elasticity. A new state vector is presented for three dimensional couple stress problems of prismatic structures. A new biorthogonality relation- ship of couple stress is discovered. The dual partial differential equations of couple stress problem are derived by the new state vector. By two important identical equations the new biorthogonality rela- tionship is proved based on the method of separation of variables. The symplectic orthogonality rela- tionship to three dimensional couple stress theory may be decomposed into two independently and symmetrically orthogonality relationships. The new biorthogonality relationship includes the symplec- tic orthogonality relationship. The biorthogonality relationship of couple stress may also be degener- ated into the theory of elasticity. The new state vector and biorthogonality relationship provide theo- retic foundation for the research on the schemes of separation of variables and eigenfunction expan- sion of couple stress theory.
BOUNDARY VALUE PROBLEM TO DYNAMIC EQUATION ON TIME SCALE
无
2011-01-01
In this paper we consider a nonlinear first-order boundary value problem on a time scale. The existence results of three positive solutions are obtained using fixed point theorems. Finally,examples are presented to illustrate the main results.
Van Loon, Linda M A; Van de Ven, Monique O M; Van Doesum, Karin T M; Hosman, Clemens M H; Witteman, Cilia L M
2017-03-01
When adolescents live with a parent with mental illness, they often partly take over the parental role. Little is known about the consequences of this so-called parentification on the adolescents' internalizing and externalizing problems. This survey study examined this effect cross-sectionally and longitudinally in a sample of 118 adolescents living with a parent suffering from mental health problems. In addition, the study examined a possible indirect effect via perceived stress. Path analyses were used to examine the direct associations between parentification and problem behavior as well as the indirect relations via perceived stress. The results showed that parentification was associated with both internalizing and externalizing problems cross-sectionally, but it predicted only internalizing problems 1 year later. An indirect effect of parentification on adolescent internalizing and externalizing problems via perceived stress was found, albeit only cross-sectionally. These findings imply that parentification can be stressful for adolescents who live with a parent with mental health problems, and that a greater awareness of parentification is needed to prevent adolescents from developing internalizing problems. © 2015 Family Process Institute.
Isoperimetric problems on time scales with nabla derivatives
Almeida, Ricardo; Torres, Delfim F. M.
2008-01-01
We prove a necessary optimality condition for isoperimetric problems under nabla-differentiable curves. As a consequence, the recent results of [M.R. Caputo, A unified view of ostensibly disparate isoperimetric variational problems, Appl. Math. Lett. (2008), doi:10.1016/j.aml.2008.04.004], that put together seemingly dissimilar optimal control problems in economics and physics, are extended to a generic time scale. We end with an illustrative example of application of our main result to a dyn...
Discussion and prediction on decreasing flow stress scale effect
无
2006-01-01
Based on crystal plasticity theory and surface layer model, relation of flow stress to billet dimension and grain size was built,and rationality of derived relation was verified with tensile tests of different size billets. With derived expressions, relation of decreasing flow stress scale effect to billet dimension, grain size as well as billet shape was discussed and predicted. The results show that flow stress is proportional to billet size; with decrease of grain size, flow stress is less influenced by billet dimension. When both cross section area and grain size are same, flow stress decrease of rectangular section billet or sheet is larger than that of circular section billet.
Stress and burnout in anaesthesia: a real world problem?
Rama-Maceiras, Pablo; Jokinen, Johanna; Kranke, Peter
2015-04-01
Stress and burnout have arisen as relevant problems to the healthcare workers and the health systems themselves. As anaesthesiologists work in stressful areas of the hospitals, we are exposed to these problems. In this review, we summarize recent studies regarding stress and burnout, exploring possible solutions. Almost 50% of anaesthesiologists scored positive for some of the burnout domains in different surveys, with one-third reporting high levels. The management of this problem not only needs an institutional but also an individual approach. Some recent randomized clinical trials and longitudinal studies suggest that there is some benefit of using several techniques to control stress, although benefits are still modest and most of the studies are based on transversal surveys and self-reported questionnaires. There is a lack of definitive evidence to guide the management of stress and burnout in medical professions in general and in anaesthesiology in particular. Longitudinal and interventional studies are needed to better determine ways of action. In the meantime, creating a positive work climate and institutional support as well as promoting control over one's job and the autonomy of employees are the most recommended strategies. Workers should also learn how to cope with stressors and practice personal strategies of wellness and resilience to fight against burnout.
Huang, Chien-Yu; Yen, Hsui-Chen; Tseng, Mei-Hui; Tung, Li-Chen; Chen, Ying-Dar; Chen, Kuan-Lin
2014-06-01
This study examined the effects of autistic behaviors and individual emotional and behavioral problems on parenting stress in caregivers of children with autism. Caregivers were interviewed with the Childhood Autism Rating Scale and completed the Strength and Difficulties Questionnaire and the Parenting Stress Index Short Form. Results revealed that caregivers of children with mild/moderate autistic behavior problems perceived lower parenting stress than did those of children with no or severe problems. In addition, prosocial behaviors and conduct problems respectively predicted stress in the parent-child relationship and child-related stress. The findings can provide guidance in evaluations and interventions with a focus on mitigating parenting stress in caregivers of children with autism.
Adaptation of Problem Mobile Phone Use Scale to Turkish
Ali Haydar Şar
2012-07-01
Full Text Available The aim of the study is adaptation of the “Problem Mobile Phone Use Scale ” which was developed by Bianchi ve Phillips (2005 to Turkish. In order to adapt the scale, firstly scale items were translated to Turkish by the researcher. Then translation form was further developed by consulting ten specialists. English and Turkish forms of scale were both filled by 30 undergraduate students with two-week intervals respectively. Two forms were accepted as equal since the correlation between them was 0.78. Turkish version of the scale was implemented on 300 students for validity and reliability studies. In Turkish version of the scale alpha valid value was calculated as 0.94, and reliable value vas calculated 0.88. Therefore, it can be concluded that Turkish version of the scale was reliable and valid.
Adaptation of problem mobile phone use scale to Turkish
Ali Haydar Sar
2012-08-01
Full Text Available The aim of the study is adaptation of the “Problem Mobile Phone Use Scale ” which was developed by Bianchi ve Phillips (2005 to Turkish. In order to adapt the scale, firstly scale items were translated to Turkish by the researcher. Then translation form was further developed by consulting ten specialists. English and Turkish forms of scale were both filled by 30 undergraduate students with two-week intervals respectively. Two forms were accepted as equal since the correlation between them was 0.78. Turkish version of the scale was implemented on 300 students for validity and reliability studies. In Turkish version of the scale alpha valid value was calculated as 0.94, and reliable value vas calculated 0.88. Therefore, it can be concluded that Turkish version of the scale was reliable and valid.
Construction of the Examination Stress Scale for Adolescent Students
Sung, Yao-Ting; Chao, Tzu-Yang
2015-01-01
The tools used for measuring examination stress have three main limitations: sample selected, sample sizes, and measurement contents. In this study, we constructed the Examination Stress Scale (ExamSS), and 4,717 high school students participated in this research. The results indicate that ExamSS has satisfactory reliability, construct validity,…
Huang, Chien-Yu; Yen, Hsui-Chen; Tseng, Mei-Hui; Tung, Li-Chen; Chen, Ying-Dar; Chen, Kuan-Lin
2014-01-01
This study examined the effects of autistic behaviors and individual emotional and behavioral problems on parenting stress in caregivers of children with autism. Caregivers were interviewed with the Childhood Autism Rating Scale and completed the Strength and Difficulties Questionnaire and the Parenting Stress Index Short Form. Results revealed…
22q11.2 deletion syndrome: behaviour problems of children and adolescents and parental stress.
Briegel, W; Schneider, M; Schwab, K Otfried
2008-11-01
22q11.2 deletion syndrome can be associated with a variety of somatic symptoms, developmental delays and psychiatric disorders. At present, there is little information on behaviour problems, parental stress and possible relations between these factors. Therefore, this study investigates behaviour problems of children and adolescents with 22q11.2DS, and their primary caregivers' stress. Parents of 4-17 year old subjects known to the German 22q11.2 deletion syndrome foundation were anonymously asked to fill out several questionnaires, e.g. the Child Behavior Checklist 4-18 (CBCL/4-18). The primary caregivers of 77/126 children [43 males, 34 females, mean age: 8;0 (4;0-16;11) years] sent back filled-out questionnaires. Forty-six of 76 subjects were rated as clinical on at least one of the CBCL-scales. Males had significantly higher scores on the total problems scale and the internalizing problems scale than females. The patients' age correlated with several CBCL-scales. Eleven of 49 subjects were suspicious of an autism spectrum disorder. Compared with the general population, but not with other parents of mentally and/or physically handicapped children, the primary caregivers experienced higher levels of stress, but showed normal life satisfaction. In spite of high rates of clinical behaviour problems among children and adolescents with 22q11.2DS and despite increased parental stress, most primary caregivers seem to have effective coping strategies, e.g. partnership support, to sustain normal levels of life satisfaction.
Problem-solving Model for Managing Stress and Anxiety
Taghi Abutalebi Ahmadi
2013-07-01
Full Text Available The purpose of this study is to take a look at problem-solving model for managing stress and anxiety. If each of us as a human being has an organized method for solving the different problems of our life, at that time we can get along with stress and anxiety easily. The capability of problem solving makes it possible for that person a to distinguish emotions in himself and others b to understand how excitement affects behavior c to be able to show different reactions to different emotions. If we don’t deal with emotional states such as grief, anger or anxiety properly, theses emotions will have negative effects on the physical and mental health of the person. Problem solving teaching is a treatment method by which the person learns to utilize effective cognitive skills to get along with inter-personal and problematic situations. In this study, we would like to emphasize the importance of the problem-solving teaching, and learn about its varieties and principal and implementation techniques, so that we can use it to manage our internal and environmental stressors. Among the various models, I will mention the easy and helpful five-step problem solving approach of Dixon and Glover (1984, as cited Yari (2009 as an example including describing the problem, stating the problem in precise and clear terms, selecting guidelines for solving the problems and prioritizing them, implementing the guidelines characterized at the previous stage, finally evaluating. At this stage, we will consider what we have gained vis a vis what we had hoped to gain.
Does the hierarchy problem set the seesaw scale?
Kuchimanchi, Ravi
2014-01-01
We find that minimizing the number of fine tuning relations in non-supersymmetric models can determine the scales at which gauge symmetries beyond the standard model must break. We show that B-L gauge symmetry of the minimal left-right symmetric model breaks at a scale 10^{15} GeV or higher, determined by the hierarchy problem and small quark mass ratios, provided parameters that break chiral or $\\mu-$symmetries are not fine-tuned. This provides the raison d'etre for the seesaw scale ~ 10^{15}GeV indicated by neutrino experiments.
Self-reported Stress Problems among Teachers in Hong Kong
Chan, Alan H. S.; Chen, K.; Chong, Elaine Y. L.
2010-10-01
The present study was developed to comprehensively investigate the occupational health problems among teachers of primary and secondary schools in Hong Kong. A random sample of 1,710 respondents was generated from the database of Hong Kong Professional Teachers' Union (HKPTU) members. A self-administrated questionnaire was designed and sent by mail to the teachers of primary and secondary schools in HK. The results indicated that comparing with one year and five years ago, 91.6% and 97.3% of the responding teachers reported an increase of perceived stress level, respectively. Heavy workload and time pressure, education reforms, external school review, pursuing further education, and managing students' behaviour and learning were the most frequently reported sources of work stress. The four most frequently reported stress management activities were sleeping, talking to neighbors and friends, self-relaxing, and watching television, while the least frequently reported activity was doing more exercises or sports.
Bonus algorithm for large scale stochastic nonlinear programming problems
Diwekar, Urmila
2015-01-01
This book presents the details of the BONUS algorithm and its real world applications in areas like sensor placement in large scale drinking water networks, sensor placement in advanced power systems, water management in power systems, and capacity expansion of energy systems. A generalized method for stochastic nonlinear programming based on a sampling based approach for uncertainty analysis and statistical reweighting to obtain probability information is demonstrated in this book. Stochastic optimization problems are difficult to solve since they involve dealing with optimization and uncertainty loops. There are two fundamental approaches used to solve such problems. The first being the decomposition techniques and the second method identifies problem specific structures and transforms the problem into a deterministic nonlinear programming problem. These techniques have significant limitations on either the objective function type or the underlying distributions for the uncertain variables. Moreover, these ...
Problems of allometric scaling analysis : Examples from mammalian reproductive biology
Martin, RD; Genoud, M; Hemelrijk, CK
2005-01-01
Biological scaling analyses employing the widely used bivariate allometric model are beset by at least four interacting problems: (1) choice of an appropriate best-fit line with due attention to the influence of outliers; (2) objective recognition of divergent subsets in the data (allometric grades)
Problems of allometric scaling analysis : Examples from mammalian reproductive biology
Martin, RD; Genoud, M; Hemelrijk, CK
Biological scaling analyses employing the widely used bivariate allometric model are beset by at least four interacting problems: (1) choice of an appropriate best-fit line with due attention to the influence of outliers; (2) objective recognition of divergent subsets in the data (allometric
Homogeneous Earthquake Faulting, Stress and Fault Strength on Kilometer Scales
Hardebeck, J. L.
2006-12-01
I investigate small-scale fault structure using three new high-quality focal mechanism datasets of small (MLoma Prieta earthquake. I quantify the degree of mechanism variability on a range of length scales, by comparing the hypocentral distance between every pair of events and the angular difference between their focal mechanisms. I explore the implications of focal mechanism variability for the heterogeneity or homogeneity of stress and fault strength on various length scales. Focal mechanisms are very similar, often identical to within the 1σ uncertainty of ~25°, on small length scales of effect of uncertainty in earthquake locations and focal mechanisms on the apparent mechanism variability. The result that fault geometry, stress and fault strength are generally homogeneous on ~10 km length scales is encouraging for understanding earthquake physics. It may be possible to measure these parameters with enough precision to be useful in studying and modeling large earthquakes and the behavior of major faults.
Fundamental Enabling Issues in Nanotechnology: Stress at the Atomic Scale
Floro, Jerrold Anthony [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Univ. of Virginia, Charlottesville, VA (United States). Dept. of Materials Science and Engineering; Foiles, Stephen Martin [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Hearne, Sean Joseph [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Hoyt, Jeffrey John [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); McMaster Univ., Hamilton, ON (Canada); Seel, Steven Craig [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Emcore Corporation, Albuquerque, NM (United States); Webb, Edmund Blackburn [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Morales, Alfredo Martin [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Zimmerman, Jonathan A. [Sandia National Lab. (SNL-CA), Livermore, CA (United States)
2007-10-01
To effectively integrate nanotechnology into functional devices, fundamental aspects of material behavior at the nanometer scale must be understood. Stresses generated during thin film growth strongly influence component lifetime and performance; stress has also been proposed as a mechanism for stabilizing supported nanoscale structures. Yet the intrinsic connections between the evolving morphology of supported nanostructures and stress generation are still a matter of debate. This report presents results from a combined experiment and modeling approach to study stress evolution during thin film growth. Fully atomistic simulations are presented predicting stress generation mechanisms and magnitudes during all growth stages, from island nucleation to coalescence and film thickening. Simulations are validated by electrodeposition growth experiments, which establish the dependence of microstructure and growth stresses on process conditions and deposition geometry. Sandia is one of the few facilities with the resources to combine experiments and modeling/theory in this close a fashion. Experiments predicted an ongoing coalescence process that generates signficant tensile stress. Data from deposition experiments also support the existence of a kinetically limited compressive stress generation mechanism. Atomistic simulations explored island coalescence and deposition onto surfaces intersected by grain boundary structures to permit investigation of stress evolution during later growth stages, e.g., continual island coalescence and adatom incorporation into grain boundaries. The predictive capabilities of simulation permit direct determination of fundamental processes active in stress generation at the nanometer scale while connecting those processes, via new theory, to continuum models for much larger island and film structures. Our combined experiment and simulation results reveal the necessary materials science to tailor stress, and therefore performance, in
Finite-size scaling approach to dynamic storage allocation problem
Seyed-allaei, Hamed
2003-09-01
It is demonstrated how dynamic storage allocation algorithms can be analyzed in terms of finite-size scaling. The method is illustrated in the three simple cases of the first-fit, next-fit and best-fit algorithms, and the system works at full capacity. The analysis is done from two different points of view-running speed and employed memory. In both cases, and for all algorithms, it is shown that a simple scaling function exists and the relevant exponents are calculated. The method can be applied on similar problems as well.
Nonlinear triple-point problems on time scales
Douglas R. Anderson
2004-04-01
Full Text Available We establish the existence of multiple positive solutions to the nonlinear second-order triple-point boundary-value problem on time scales, $$displaylines{ u^{Delta abla}(t+h(tf(t,u(t=0, cr u(a=alpha u(b+delta u^Delta(a,quad eta u(c+gamma u^Delta(c=0 }$$ for $tin[a,c]subsetmathbb{T}$, where $mathbb{T}$ is a time scale, $eta, gamma, deltage 0$ with $Beta+gamma>0$, $0
The problem of professional burnout in stress management
Makasheva Natalia
2016-01-01
Full Text Available The problem of professional burnout is extremely relevant in current stress management. By its nature, professional burnout is a unique type of stress syndrome that is characterized by emotional exhaustion. It leads to loss of energy and interest in one’s job. A burnout could be the result of such syndromes as – burnout and boreout. It could emerge as the reaction of the organism to the high working intensity and stress working conditions or due to the boredom and absence of the sphere for professional realization. Both syndromes negatively influence the professional activity and require serious research and an adequate approach to the study. Studies have been conducted in the higher educational environment and among production employees. The studies were conducted with the application of the existing tests for revealing the “boreout” and “burnout” syndromes. Studies have shown that the syndrome “burnout” is common among workers with free working regulations, whose work requires greater independence, initiative and responsibility. According to the results of the study, the employees who are more free in the performance of their professional duties (teachers, managers are less subjected to the boreout syndrome. For the prevention and control of professional burnout company management needs to apply the achievements of stress management.
The renormalization scale-setting problem in QCD
Wu, Xing-Gang [Chongqing Univ. (China); Brodsky, Stanley J. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Mojaza, Matin [SLAC National Accelerator Lab., Menlo Park, CA (United States); Univ. of Southern Denmark, Odense (Denmark)
2013-09-01
A key problem in making precise perturbative QCD predictions is to set the proper renormalization scale of the running coupling. The conventional scale-setting procedure assigns an arbitrary range and an arbitrary systematic error to fixed-order pQCD predictions. In fact, this ad hoc procedure gives results which depend on the choice of the renormalization scheme, and it is in conflict with the standard scale-setting procedure used in QED. Predictions for physical results should be independent of the choice of the scheme or other theoretical conventions. We review current ideas and points of view on how to deal with the renormalization scale ambiguity and show how to obtain renormalization scheme- and scale-independent estimates. We begin by introducing the renormalization group (RG) equation and an extended version, which expresses the invariance of physical observables under both the renormalization scheme and scale-parameter transformations. The RG equation provides a convenient way for estimating the scheme- and scale-dependence of a physical process. We then discuss self-consistency requirements of the RG equations, such as reflexivity, symmetry, and transitivity, which must be satisfied by a scale-setting method. Four typical scale setting methods suggested in the literature, i.e., the Fastest Apparent Convergence (FAC) criterion, the Principle of Minimum Sensitivity (PMS), the Brodsky–Lepage–Mackenzie method (BLM), and the Principle of Maximum Conformality (PMC), are introduced. Basic properties and their applications are discussed. We pay particular attention to the PMC, which satisfies all of the requirements of RG invariance. Using the PMC, all non-conformal terms associated with the β-function in the perturbative series are summed into the running coupling, and one obtains a unique, scale-fixed, scheme-independent prediction at any finite order. The PMC provides the principle underlying the BLM method, since it gives the general rule for extending
Dressed skeleton expansion and the coupling scale ambiguity problem
Lu, Hung Jung.
1992-09-01
Perturbative expansions in quantum field theories are usually expressed in powers of a coupling constant. In principle, the infinite sum of the expansion series is independent of the renormalization scale of the coupling constant. In practice, there is a remnant dependence of the truncated series on the renormalization scale. This scale ambiguity can severely restrict the predictive power of theoretical calculations. The dressed skeleton expansion is developed as a calculational method which avoids the coupling scale ambiguity problem. In this method, physical quantities are expressed as functional expansions in terms of a coupling vertex function. The arguments of the vertex function are given by the physical momenta of each process. These physical momenta effectively replace the unspecified renormalization scale and eliminate the ambiguity problem. This method is applied to various field theoretical models and its main features and limitations are explored. For quantum chromodynamics, an expression for the running coupling constant of the three-gluon vertex is obtained. The effective coupling scale of this vertex is shown to be essentially given by [mu][sup 2] [approximately] Q[sub min][sup 2]Q[sub med][sup 2]/Q[sub max][sup 2] where Q[sub min][sup 2]Q[sub med][sup 2]/Q[sub max][sup 2] are respectively the smallest, the next-to-smallest and the largest scale among the three gluon virtualities. This functional form suggests that the three-gluon vertex becomes non-perturbative at asymmetric momentum configurations. Implications for four-jet physics is discussed.
Dressed skeleton expansion and the coupling scale ambiguity problem
Lu, Hung Jung
1992-09-01
Perturbative expansions in quantum field theories are usually expressed in powers of a coupling constant. In principle, the infinite sum of the expansion series is independent of the renormalization scale of the coupling constant. In practice, there is a remnant dependence of the truncated series on the renormalization scale. This scale ambiguity can severely restrict the predictive power of theoretical calculations. The dressed skeleton expansion is developed as a calculational method which avoids the coupling scale ambiguity problem. In this method, physical quantities are expressed as functional expansions in terms of a coupling vertex function. The arguments of the vertex function are given by the physical momenta of each process. These physical momenta effectively replace the unspecified renormalization scale and eliminate the ambiguity problem. This method is applied to various field theoretical models and its main features and limitations are explored. For quantum chromodynamics, an expression for the running coupling constant of the three-gluon vertex is obtained. The effective coupling scale of this vertex is shown to be essentially given by {mu}{sup 2} {approximately} Q{sub min}{sup 2}Q{sub med}{sup 2}/Q{sub max}{sup 2} where Q{sub min}{sup 2}Q{sub med}{sup 2}/Q{sub max}{sup 2} are respectively the smallest, the next-to-smallest and the largest scale among the three gluon virtualities. This functional form suggests that the three-gluon vertex becomes non-perturbative at asymmetric momentum configurations. Implications for four-jet physics is discussed.
Advances in research of stress-assisted corrosion fatigue problem
TANG Zhi-bo; LI Qiang
2007-01-01
Ceramic materials are notable for their rigidity, insulation and resistance to hostile environment. Nevertheless, if a stressed ceramic component is exposed to chemical attack, it may suffer from a form of delayed fracture known as static fatigue.From the point of view of a designer, it is clearly desirable to determine the behavior of sub-critical crack growth; the crack path and crack growth rate, as a function of material properties and loading conditions are of particular interest. This paper presents a review of advances in stress assisted corrosion problem in history and its corresponding numerical approaches in the last decades,and finally, comes up with consideration and crucial suggestions for future work.
Revision and validation of a scale to assess pregnancy stress.
Chen, Chung-Hey
2015-03-01
Pregnancy is a potentially stressful event. Prenatal stress alters maternal endocrine and immune systems, has been implicated in the etiology of prenatal complications or postnatal psychiatric disorders, and may adversely affect fetal health. The 30-item Pregnancy Stress Rating Scale (PSRS), initially developed in 1983 by Chen and colleagues, is the only measure to date designed specifically to evaluate prenatal stress. The purpose of this study was to reconsider and revise the 30-item PSRS and validate the new PSRS. A cross-sectional design was used. Adding new items of pregnancy stress generated from clinical experience and expert recommendations resulted in a 40-item revised PSRS that was more reflective of current social conditions. Three hundred pregnant women, recruited from the antenatal clinic of a medical center in southern Taiwan, completed the revised PSRS to assess its internal consistency, test-retest reliability, construct validity, and convergent and discriminate validity. The final 36-item PSRS (PSRS36) was derived by deleting four items with relatively low item-total correlation coefficients or factor loadings. The resultant 36-item scale showed good internal consistency (α = .92) and 2-week test-retest reliability (r = .82). Factor analysis confirmed construct validity and suggested five prenatal stress dimensions, which explained 52.17% of the total variance. Convergent and discriminate validities were indicated by significant correlations among the PSRS36, Perceived Stress Scale, and Interpersonal Support Evaluation List. The PSRS36 is a psychometrically sound and practical tool for nurses and other healthcare providers to assess prenatal stress and to examine intervention protocols in Taiwanese prenatal women. More research is recommended to determine whether the PSRS36 may be used in other racial-ethnic groups.
SOLVING TRUST REGION PROBLEM IN LARGE SCALE OPTIMIZATION
Bing-sheng He
2000-01-01
This paper presents a new method for solving the basic problem in the “model trust region” approach to large scale minimization: Compute a vector x such that 1/2xTHx + cTx = min, subject to the constraint ‖x‖2≤a. The method is a combination of the CG method and a projection and contraction (PC) method. The first (CG) method with x0 = 0 as the start point either directly offers a solution of the problem, or--as soon as the norm of the iterate greater than a, --it gives a suitable starting point and a favourable choice of a crucial scaling parameter in the second (PC) method. Some numerical examples are given, which indicate that the method is applicable.
Problems of allometric scaling analysis: examples from mammalian reproductive biology.
Martin, Robert D; Genoud, Michel; Hemelrijk, Charlotte K
2005-05-01
Biological scaling analyses employing the widely used bivariate allometric model are beset by at least four interacting problems: (1) choice of an appropriate best-fit line with due attention to the influence of outliers; (2) objective recognition of divergent subsets in the data (allometric grades); (3) potential restrictions on statistical independence resulting from phylogenetic inertia; and (4) the need for extreme caution in inferring causation from correlation. A new non-parametric line-fitting technique has been developed that eliminates requirements for normality of distribution, greatly reduces the influence of outliers and permits objective recognition of grade shifts in substantial datasets. This technique is applied in scaling analyses of mammalian gestation periods and of neonatal body mass in primates. These analyses feed into a re-examination, conducted with partial correlation analysis, of the maternal energy hypothesis relating to mammalian brain evolution, which suggests links between body size and brain size in neonates and adults, gestation period and basal metabolic rate. Much has been made of the potential problem of phylogenetic inertia as a confounding factor in scaling analyses. However, this problem may be less severe than suspected earlier because nested analyses of variance conducted on residual variation (rather than on raw values) reveals that there is considerable variance at low taxonomic levels. In fact, limited divergence in body size between closely related species is one of the prime examples of phylogenetic inertia. One common approach to eliminating perceived problems of phylogenetic inertia in allometric analyses has been calculation of 'independent contrast values'. It is demonstrated that the reasoning behind this approach is flawed in several ways. Calculation of contrast values for closely related species of similar body size is, in fact, highly questionable, particularly when there are major deviations from the best
Finite-Size Scaling in Random K-SAT Problems
Ha, Meesoon; Lee, Sang Hoon; Jeon, Chanil; Jeong, Hawoong
2010-03-01
We propose a comprehensive view of threshold behaviors in random K-satisfiability (K-SAT) problems, in the context of the finite-size scaling (FSS) concept of nonequilibrium absorbing phase transitions using the average SAT (ASAT) algorithm. In particular, we focus on the value of the FSS exponent to characterize the SAT/UNSAT phase transition, which is still debatable. We also discuss the role of the noise (temperature-like) parameter in stochastic local heuristic search algorithms.
PRESUMPTIVE STRESSFUL LIFE EVENTS SCALE (PSLES) — A NEW STRESSFUL LIFE EVENTS SCALE FOR USE IN INDIA
Singh, Gurmeet; Kaur, Dalbir; Kaur, Harsharan
1984-01-01
SUMMARY Using an open ended question along with Holme's and Rahe's Social Readjustment Rating Schedule on a sample of two hundred adult subjects, a suitable scale of stressful life events experienced by the Indian population was constructed and standardized for two time spaces, that is, last one year and life time. Analysis of various demographic variables for this population revealed no differences on this scale for age, marital state, education and occupation. However, marked sex differences in the perceived stressfulness were observed for three of the items. The scale items were further divided into desirable, undesirable and ambiguous and also into personal and impersonal Categories. Statistically significant difference were observed between the desirable and undesirable items, the latter being perceived as more stressful. Norms for total number of life events experienced as well as the presumptive stress score were established for each event for this population. The frequency of occurrence of each event in our population was also obtained. It was Calculated that individuals in our society are likely to experience an average of two stressful life events in the past one year and ten events in a life time without suffering any adverse physical or psychological disturbance. The scale is simple to administer to literate and illiterate subjects. PMID:21965968
Solving large scale traveling salesman problems by chaotic neurodynamics.
Hasegawa, Mikio; Ikeguch, Tohru; Aihara, Kazuyuki
2002-03-01
We propose a novel approach for solving large scale traveling salesman problems (TSPs) by chaotic dynamics. First, we realize the tabu search on a neural network, by utilizing the refractory effects as the tabu effects. Then, we extend it to a chaotic neural network version. We propose two types of chaotic searching methods, which are based on two different tabu searches. While the first one requires neurons of the order of n2 for an n-city TSP, the second one requires only n neurons. Moreover, an automatic parameter tuning method of our chaotic neural network is presented for easy application to various problems. Last, we show that our method with n neurons is applicable to large TSPs such as an 85,900-city problem and exhibits better performance than the conventional stochastic searches and the tabu searches.
The construct validity of the Perceived Stress Scale
Nielsen, Marie Germund; Ørnbøl, Eva; Vestergaard, Mogens
2016-01-01
særligt de positivt formulerede spørgsmål, der giver udfordringer, og kønsforskelle kan ikke alene forklare de to dimensioner i skalaen. Der er i dag ingen psykometrisk test til måling af stress hos patienter i almen praksis, og et muligt instrument kunne være PSS-10 skalaen, hvis de identificerede......Denne artikel er en konstruktionsvalidering af Sheldon Cohens stress-skala, Perceived Stress Scale (PSS-10), som anvendes i fx de nationale ”Hvordan har du det?”-undersøgelser til at måle graden af stress i den danske befolkning. I alt 32,374 borgere fra Region Midtjylland udfyldte PSS-10 som en...
Scale Development: Factors Affecting Diet, Exercise, and Stress Management (FADESM
Nitzke Susan
2008-02-01
Full Text Available Abstract Background The objective of this study was to develop scales measuring personal and environmental factors that affect dietary fat intake behavior, physical activity, and stress management in low-income mothers. Methods FADESM (factors affecting diet, exercise, and stress management scales were developed using the Social Cognitive Theory to measure personal (outcome expectancies, self-efficacy, emotional coping response and environmental (physical environment, social environment, situation factors affecting dietary fat intake behavior, physical activity, and stress management. Low-income African American and white mothers were recruited from the Special Supplemental Nutrition Program for Women, Infants, and Children in three counties in Michigan. In Phase one, 45 mothers completed individual cognitive interviews. Content analyses were performed. In Phase two, items modified from the cognitive interviews were administered to 216 mothers. Factor analysis and multiple indicators/multiple causes were performed. Results Results of cognitive interviews were used to revise items for the instrument that was tested in Phase two. The factor solution revealed 19 dimensions to measure personal and environmental factors affecting dietary fat intake behavior (three dimensions, physical activity (eight dimensions, and stress management (eight dimensions. Results of multiple indicators/multiple causes model showed scale invariance. Of 19 dimensions, 15 had Cronbach alpha between 0.76 and 0.94 and four were between 0.66 and 0.69. All dimensions had composite construct reliability scores between 0.74 to 0.97 and satisfactory construct and discriminant validities. Conclusion The theory-based FADESM scales have documented good validity and reliability for measuring factors affecting dietary fat intake behavior, physical activity, and stress management in low-income women. Results of this study support the use of these scales with low-income African American
Problem-Solving Appraisal, Stress, Hopelessness, and Suicide Ideation in a College Population.
Dixon, Wayne A.; And Others
1991-01-01
College students completed measures of problem-solving appraisal, negative life stress, and suicide ideation (Study 1, n=1,277) or problem-solving appraisal, negative life stress, and hopelessness (Study 2, n=382). Results from both studies suggest that problem-solving appraisal and negative life stress are significant independent predictors of…
Abdollahi, Abbas; Abu Talib, Mansor; Carlbring, Per; Harvey, Richard; Yaacob, Siti Nor; Ismail, Zanariah
2016-06-26
This study was designed to examine the relationships between problem-solving skills, hardiness, and perceived stress and to test the moderating role of hardiness in the relationship between problem-solving skills and perceived stress among 500 undergraduates from Malaysian public universities. The analyses showed that undergraduates with poor problem-solving confidence, external personal control of emotion, and approach-avoidance style were more likely to report perceived stress. Hardiness moderated the relationships between problem-solving skills and perceived stress. These findings reinforce the importance of moderating role of hardiness as an influencing factor that explains how problem-solving skills affect perceived stress among undergraduates.
Leadership solves collective action problems in small-scale societies.
Glowacki, Luke; von Rueden, Chris
2015-12-01
Observation of leadership in small-scale societies offers unique insights into the evolution of human collective action and the origins of sociopolitical complexity. Using behavioural data from the Tsimane forager-horticulturalists of Bolivia and Nyangatom nomadic pastoralists of Ethiopia, we evaluate the traits of leaders and the contexts in which leadership becomes more institutional. We find that leaders tend to have more capital, in the form of age-related knowledge, body size or social connections. These attributes can reduce the costs leaders incur and increase the efficacy of leadership. Leadership becomes more institutional in domains of collective action, such as resolution of intragroup conflict, where collective action failure threatens group integrity. Together these data support the hypothesis that leadership is an important means by which collective action problems are overcome in small-scale societies.
Grover, Kelly E; Green, Kelly L; Pettit, Jeremy W; Monteith, Lindsey L; Garza, Monica J; Venta, Amanda
2009-12-01
The present study examined the unique and interactive effects of stress and problem-solving skills on suicidal behaviors among 102 inpatient adolescents. As expected, life event stress and chronic stress each significantly predicted suicidal ideation and suicide attempt. Problem solving significantly predicted suicidal ideation, but not suicide attempt. Problem solving moderated the associations between life event stress and suicidal behaviors, as well as between chronic stress and suicidal ideation, but not chronic stress and suicide attempt. At high levels of stress, adolescents with poor problem-solving skills experienced elevated suicidal ideation and were at greater risk of making a nonfatal suicide attempt. The interactive effects decreased to non-significance after controlling for depressive symptoms and hopelessness. Clinical implications are discussed.
A dissonant scale: stress recognition in the SAQ
2013-01-01
Background Our previous analyses using the Stress Recognition subscale of the Safety Attitudes Questionnaire (SAQ) resulted in significant effect estimates with equally opposing explanations. We suspected construct validity issues and investigated such using our own data and correlation matrices of previous published studies. Methods The correlation matrices for each of the SAQ subscales from two previous studies by Speroff and Taylor were replicated and compared. The SAS Proc Factor procedure and the PRIORS = SMC option were used to perform Common Factor Analysis. Results The correlation matrices of both studies were very similar. Teamwork, Safety Climate, Job Satisfaction, Perceptions of Management and Working Conditions were well-correlated. The correlations ranged from 0.53 to 0.76. For Stress Recognition correlations ranged from -0.15 to 0.03. Common Factor Analysis confirmed the isolation of Stress Recognition. CFA returned a strong one-factor model that explained virtually all of the communal variance. Stress Recognition loaded poorly on this factor in both instances, and the CFA indicated that 96.4-100.0% of the variance associated with Stress Recognition was unique to that subscale, and not shared with the other 5 subscales. Conclusions We conclude that the Stress Recognition subscale does not fit into the overall safety climate construct the SAQ intended to reflect. We recommend that this domain be omitted from overall safety climate scale score calculations, and clearly identified as an important yet distinct organizational construct. We suggest that this subscale be investigated for its true meaning, characterized as such, and findings conveyed to SAQ end users. We make no argument against Stress Recognition as an important organizational metric, rather we suggest that as a stand-alone construct its current packaging within the SAQ may be misleading for those intent on intervention development and evaluation in healthcare settings if they interpret
Groundwater Development Stress: Global-Scale Indices Compared to Regional Modeling.
Alley, William M; Clark, Brian R; Ely, David M; Faunt, Claudia C
2017-08-15
The increased availability of global datasets and technologies such as global hydrologic models and the Gravity Recovery and Climate Experiment (GRACE) satellites have resulted in a growing number of global-scale assessments of water availability using simple indices of water stress. Developed initially for surface water, such indices are increasingly used to evaluate global groundwater resources. We compare indices of groundwater development stress for three major agricultural areas of the United States to information available from regional water budgets developed from detailed groundwater modeling. These comparisons illustrate the potential value of regional-scale analyses to supplement global hydrological models and GRACE analyses of groundwater depletion. Regional-scale analyses allow assessments of water stress that better account for scale effects, the dynamics of groundwater flow systems, the complexities of irrigated agricultural systems, and the laws, regulations, engineering, and socioeconomic factors that govern groundwater use. Strategic use of regional-scale models with global-scale analyses would greatly enhance knowledge of the global groundwater depletion problem. © 2017, National Ground Water Association.
Scaled first-order methods for a class of large-scale constrained least square problems
Coli, Vanna Lisa; Ruggiero, Valeria; Zanni, Luca
2016-10-01
Typical applications in signal and image processing often require the numerical solution of large-scale linear least squares problems with simple constraints, related to an m × n nonnegative matrix A, m « n. When the size of A is such that the matrix is not available in memory and only the operators of the matrix-vector products involving A and AT can be computed, forward-backward methods combined with suitable accelerating techniques are very effective; in particular, the gradient projection methods can be improved by suitable step-length rules or by an extrapolation/inertial step. In this work, we propose a further acceleration technique for both schemes, based on the use of variable metrics tailored for the considered problems. The numerical effectiveness of the proposed approach is evaluated on randomly generated test problems and real data arising from a problem of fibre orientation estimation in diffusion MRI.
Acculturation stress and drinking problems among urban heavy drinking Latinos in the Northeast.
Lee, Christina S; Colby, Suzanne M; Rohsenow, Damaris J; López, Steven R; Hernández, Lynn; Caetano, Raul
2013-01-01
This study investigates the relationship between the level of acculturation and acculturation stress and the extent to which each predicts problems related to drinking. Hispanics who met criteria for hazardous drinking completed measures of acculturation, acculturation stress, and drinking problems. Sequential multiple regression was used to determine whether the levels of self-reported acculturation stress predicted concurrent alcohol problems after controlling for the predictive value of the acculturation level. Acculturation stress accounted for a significant variance in drinking problems, while adjusting for acculturation, income, and education. Choosing to drink in response to acculturation stress should be an intervention target with Hispanic heavy drinkers.
Acculturation Stress and Drinking Problems Among Urban Heavy Drinking Latinos in the Northeast
Lee, Christina S.; Colby, Suzanne M.; Rohsenow, Damaris J.; López, Steven R.; Hernández, Lynn; Caetano, Raul
2014-01-01
This study investigates the relationship between level of acculturation and acculturation stress, and the extent to which each predicts problems related to drinking. Hispanics who met criteria for hazardous drinking completed measures of acculturation, acculturation stress, and drinking problems. Sequential multiple regression was used to determine whether levels of self-reported acculturation stress predicted concurrent alcohol problems after controlling for the predictive value of acculturation level. Acculturation stress accounted for significant variance in drinking problems while adjusting for acculturation, income, and education. Choosing to drink in response to acculturation stress should be an intervention target with Hispanic heavy drinkers. PMID:24215224
Ek-uma Imkome
2017-04-01
Full Text Available This study aimed to psychometrically test a Thai Stressful Life Events Rating Scale (TSLERS. Factor analysis was done on data collected from 313 patients with schizophrenia and methamphetamine abuse in Thailand from April to May, 2015. Results identified the following problems impacting physical and mental health: social relationship and social concerns, money, family life, life security, and career. Evaluation of the psychometric scale properties demonstrated acceptable validity and reliability. TSLERS provided scientific and empirical data about stressful life events of patients with schizophrenia and methamphetamine abuse, and was suitable for stress detection and suggesting further innovations.
The Difficult Patient Stress Scale: a new instrument to measure interpersonal stress in nursing.
Santamaria, N
1995-01-01
This study describes the development of the Difficult Patient Stress Scale, an instrument designed to investigate the stress that nurses experience when they are involved in interpersonal conflict with patients. The DPSS is based on the theoretical conceptualization of stress proposed by DeLongis, Lazarus and Folkman and on the personality theory of Individual Psychology. The DPSS utilises visual analog scales to measure nurses' responses to hypothetical scenarios that present typical, difficult nurse-patient situations. The DPSS has been tested over a period of two years with 228 nurses and the results to date indicate that it is valid, reliable and suitable for use in the clinical environment. It is proposed that it may provide a useful instrument for exploring the impact and frequency of interpersonal stressors in nursing and may assist in the development of educational programs to better equip nurses to deal with interpersonal nurse-patient conflict.
Development of the Seasonal Migrant Agricultural Worker Stress Scale in Sanliurfa, Southeast Turkey.
Simsek, Zeynep; Ersin, Fatma; Kirmizitoprak, Evin
2016-01-01
Stress is one of the main causes of health problems, especially mental disorders. These health problems cause a significant amount of ability loss and increase cost. It is estimated that by 2020, mental disorders will constitute 15% of the total disease burden, and depression will rank second only after ischemic heart disease. Environmental experiences are paramount in increasing the liability of mental disorders in those who constantly face sustained high levels of stress. The objective of this study was to develop a stress scale for seasonal migrant agricultural workers aged 18 years and older. The sample consisted of 270 randomly selected seasonal migrant agricultural workers. The average age of the participants was 33.1 ± 14, and 50.7% were male. The Cronbach alpha coefficient and test-retest methods were used for reliability analyses. Although the factor analysis was performed for the structure validity of the scale, the Kaiser-Meyer-Olkin coefficient and Bartlett test were used to determine the convenience of the data for the factor analysis. In the reliability analyses, the Cronbach alpha coefficient of internal consistency was calculated as .96, and the test-retest reliability coefficient was .81. In the exploratory factor analysis for validity of the scale, four factors were obtained, and the factors represented workplace physical conditions (25.7% of the total variance), workplace psychosocial and economic factors (19.3% of the total variance), workplace health problems (15.2% of the total variance), and school problems (10.1% of the total variance). The four factors explained 70.3% of the total variance. As a result of the expert opinions and analyses, a stress scale with 48 items was developed. The highest score to be obtained from the scale was 144, and the lowest score was 0. The increase in the score indicates the increase in the stress levels. The findings show that the scale is a valid and reliable assessment instrument that can be used in
Saddle stresses for generic theories with a preferred acceleration scale
Magueijo, Joao
2012-01-01
We show how scaling arguments may be used to generate templates for the tidal stresses around saddles for a vast class of MONDian theories {\\it detached from their obligations as dark matter alternatives}. Such theories are to be seen simply as alternative theories of gravity with a preferred acceleration scale, and could be tested in the solar system by extending the LISA Pathfinder mission. The constraints thus obtained may then be combined, if one wishes, with requirements arising from astrophysical and cosmological applications, but a clear separation of the issues is achieved. The central technical content of this paper is the derivation of a scaling prescription allowing complex numerical work to be bypassed in the generation of templates.
Lexical stress assignment as a problem of probabilistic inference.
Jouravlev, Olessia; Lupker, Stephen J
2015-10-01
A new conceptualization of the process of stress assignment, couched in the principles of (Bayesian) probabilistic inference, is introduced in this paper. According to this approach, in deciding where to place stress in a polysyllabic word, a reader estimates the posterior probabilities of alternative stress patterns. This estimation is accomplished by adjusting a prior belief about the likelihoods of alternative stress patterns (derived from experience with the distribution of stress patterns in the language) by using lexical and non-lexical sources of evidence for stress derived from the orthographic input. The proposed theoretical framework was used to compute probabilities of stress patterns for Russian disyllabic words and nonwords which were then compared with the performance of readers. The results showed that the estimated probabilities of stress patterns were reflective of actual stress assignment performance and of naming latencies, suggesting that the mechanisms that are involved in the process of stress assignment might indeed be inferentially-based.
Application of scaled boundary finite element method in static and dynamic fracture problems
Zhenjun Yang
2006-01-01
The scaled boundary finite element method (SBFEM) is a recently developed numerical method combining advantages of both finite element methods (FEM)and boundary element methods (BEM) and with its own special features as well. One of the most prominent advantages is its capability of calculating stress intensity factors (SIFs) directly from the stress solutions whose singularities at crack tips are analytically represented. This advantage is taken in this study to model static and dynamic fracture problems. For static problems, a remeshing algorithm as simple as used in the BEM is developed while retaining the generality and flexibility of the FEM. Fully-automatic modelling of the mixed-mode crack propagation is then realised by combining the remeshing algorithm with a propagation criterion.F0r dynamic fracture problems, a newly developed series-increasing solution to the SBFEM governing equations in the frequency domain is applied to calculate dynamic SIFs. Three plane problems are modelled. The numerical results show that the SBFEM can accurately predict static and dynamic SIFs, cracking paths and load-displacement curves, using only a fraction of degrees of freedom generally needed by the traditional finite element methods.
Modeling grain-scale thermoelastic stresses on airless bodies
Molaro, J.; Byrne, S.
2013-12-01
Thermal stress weathering is the mechanical breakdown of rock from expansion and contraction caused by changes in temperature. Damage occurs in the form of microscopic cracks that result from a thermal cycle or thermal shock. This process may play an important role in the evolution of airless landscapes, by contributing to regolith production and crater degradation. Without the presence of an atmosphere, rock surfaces experience very dramatic temperature changes that induce high thermoelastic stresses in the near sub-surface. The thermoelastic behavior of each surface is primarily controlled by its distance to the sun and its solar day length, providing a unique experience on each body. For example, slowly rotating bodies that are close to the sun (such as Mercury) experience a very wide diurnal temperature range. Bodies further from the sun (such as NEAs) have a much smaller range, but rotate quickly and experience rapid temperature 'shocks' during sunrise/set. While many studies suggest stresses induced by these temperature changes may cause rock breakdown, the extent of the damage produced as a result is unknown. In this study, we modeled thermoelastic stresses produced on airless surfaces at the mineral grain scale. Finite Element Analysis of Microstructures (OOF2) is a 2-D finite element modeling program, developed at NIST and designed to help scientists calculate macroscopic properties of real or simulated microstructures. This allows us to model thermal behavior of microstructures with varying grain sizes and thermophysical properties, and to explore the relationship between the spatial and temporal temperature gradients and stress. Using OOF2, we imposed the solar and conductive fluxes calculated by our 1-D thermal model at the surface and at 5mm depth on a microstructure. The microstructure has bulk properties typical of a basalt, and a grain size of ~0.3 mm. We assigned 20% and 80% of the grains a thermal conductivity of 1 and 3 W/mK, respectively. The
Social Problem Solving as a Moderator of Stress-Related Depressive Symptoms: A Prospective Analysis.
Nezu, Arthur M.; Ronan, George F.
1988-01-01
Corroborated previous research findings demonstrating that problem-solving moderated stress-related depressive symptoms, showing effective problem solvers under high levels of stress reported significantly lower depression than did ineffective problem solvers. Used a prospective design with two measures, controlled for prior depression level, and…
Stolpe, Mathias; Stidsen, Thomas K.
2005-01-01
of minimizing the weight of a structure subject to displacement and local design-dependent stress constraints. The method iteratively solves a sequence of problems of increasing size of the same type as the original problem. The problems are defined on a design mesh which is initially coarse...... from global optimization, which have only recently become available, for solving the problems in the sequence. Numerical examples of topology design problems of continuum structures with local stress and displacement constraints are presented....
Stolpe, Mathias; Stidsen, Thomas K.
2007-01-01
of minimizing the weight of a structure subject to displacement and local design-dependent stress constraints. The method iteratively treats a sequence of problems of increasing size of the same type as the original problem. The problems are defined on a design mesh which is initially coarse...... from global optimization, which have only recently become available, for solving the problems in the sequence. Numerical examples of topology design problems of continuum structures with local stress and displacement constraints are presented....
Kernel Projection Algorithm for Large-Scale SVM Problems
王家琦; 陶卿; 王珏
2002-01-01
Support Vector Machine (SVM) has become a very effective method in sta-tistical machine learning and it has proved that training SVM is to solve Nearest Point pairProblem (NPP) between two disjoint closed convex sets. Later Keerthi pointed out that it isdifficult to apply classical excellent geometric algorithms directly to SVM and so designed anew geometric algorithm for SVM. In this article, a new algorithm for geometrically solvingSVM, Kernel Projection Algorithm, is presented based on the theorem on fixed-points of pro-jection mapping. This new algorithm makes it easy to apply classical geometric algorithmsto solving SVM and is more understandable than Keerthi's. Experiments show that the newalgorithm can also handle large-scale SVM problems. Geometric algorithms for SVM, such asKeerthi's algorithm, require that two closed convex sets be disjoint and otherwise the algo-rithms are meaningless. In this article, this requirement will be guaranteed in theory by usingthe theoretic result on universal kernel functions.
Bos, Elisabeth H.; Bouhuys, Antoinette L.; Geerts, Eirwin; van Os, Titus W. D. P.; Ormel, Johan
Background.- Interpersonal difficulties and stressful life events are important etiological factors in (recurrence of) depression. This study examines whether stressful life events mediate the influence of problems in nonverbal communication on recurrence of depression. Methods.- We registered
Bos, Elisabeth H.; Bouhuys, Antoinette L.; Geerts, Eirwin; van Os, Titus W. D. P.; Ormel, Johan
2007-01-01
Background.- Interpersonal difficulties and stressful life events are important etiological factors in (recurrence of) depression. This study examines whether stressful life events mediate the influence of problems in nonverbal communication on recurrence of depression. Methods.- We registered nonve
Water stress strengthens mutualism among ants, trees, and scale insects.
Elizabeth G Pringle
2013-11-01
Full Text Available Abiotic environmental variables strongly affect the outcomes of species interactions. For example, mutualistic interactions between species are often stronger when resources are limited. The effect might be indirect: water stress on plants can lead to carbon stress, which could alter carbon-mediated plant mutualisms. In mutualistic ant-plant symbioses, plants host ant colonies that defend them against herbivores. Here we show that the partners' investments in a widespread ant-plant symbiosis increase with water stress across 26 sites along a Mesoamerican precipitation gradient. At lower precipitation levels, Cordia alliodora trees invest more carbon in Azteca ants via phloem-feeding scale insects that provide the ants with sugars, and the ants provide better defense of the carbon-producing leaves. Under water stress, the trees have smaller carbon pools. A model of the carbon trade-offs for the mutualistic partners shows that the observed strategies can arise from the carbon costs of rare but extreme events of herbivory in the rainy season. Thus, water limitation, together with the risk of herbivory, increases the strength of a carbon-based mutualism.
Water stress strengthens mutualism among ants, trees, and scale insects.
Pringle, Elizabeth G; Akçay, Erol; Raab, Ted K; Dirzo, Rodolfo; Gordon, Deborah M
2013-11-01
Abiotic environmental variables strongly affect the outcomes of species interactions. For example, mutualistic interactions between species are often stronger when resources are limited. The effect might be indirect: water stress on plants can lead to carbon stress, which could alter carbon-mediated plant mutualisms. In mutualistic ant-plant symbioses, plants host ant colonies that defend them against herbivores. Here we show that the partners' investments in a widespread ant-plant symbiosis increase with water stress across 26 sites along a Mesoamerican precipitation gradient. At lower precipitation levels, Cordia alliodora trees invest more carbon in Azteca ants via phloem-feeding scale insects that provide the ants with sugars, and the ants provide better defense of the carbon-producing leaves. Under water stress, the trees have smaller carbon pools. A model of the carbon trade-offs for the mutualistic partners shows that the observed strategies can arise from the carbon costs of rare but extreme events of herbivory in the rainy season. Thus, water limitation, together with the risk of herbivory, increases the strength of a carbon-based mutualism.
Tavakoli, Ruhollah
2010-01-01
The structure of many real-world optimization problems includes minimization of a nonlinear (or quadratic) functional subject to bound and singly linear constraints (in the form of either equality or bilateral inequality) which are commonly called as continuous knapsack problems. Since there are efficient methods to solve large-scale bound constrained nonlinear programs, it is desirable to adapt these methods to solve knapsack problems, while preserving their efficiency and convergence theories. The goal of this paper is to introduce a general framework to extend a box-constrained optimization solver to solve knapsack problems. This framework includes two main ingredients which are O(n) methods; in terms of the computational cost and required memory; for the projection onto the knapsack constrains and the null-space manipulation of the related linear constraint. The main focus of this work is on the extension of Hager-Zhang active set algorithm (SIAM J. Optim. 2006, pp. 526--557). The main reasons for this ch...
Cross-cultural validity of the masculine and Feminine Gender Role Stress scales
van Well, S; Kolk, AM; Arrindell, WA
2005-01-01
The objective was to examine the usefulness of Dutch versions of the Masculine Gender Role Stress (MGRS; Eisler & Skidmore, 1987) Scale and the Feminine Gender Role Stress (Gillespie & Eisler, 1992) Scale in The Netherlands. Undergraduate students (N = 2,239) completed both gender role stress scales
Acculturation Stress and Drinking Problems Among Urban Heavy Drinking Latinos in the Northeast
Lee, Christina S.; Colby, Suzanne M.; Rohsenow, Damaris J; López, Steven R.; Hernández, Lynn; Caetano, Raul
2013-01-01
This study investigates the relationship between level of acculturation and acculturation stress, and the extent to which each predicts problems related to drinking. Hispanics who met criteria for hazardous drinking completed measures of acculturation, acculturation stress, and drinking problems. Sequential multiple regression was used to determine whether levels of self-reported acculturation stress predicted concurrent alcohol problems after controlling for the predictive value of accultura...
Acculturation Stress and Drinking Problems Among Urban Heavy Drinking Latinos in the Northeast
Lee, Christina S.; Colby, Suzanne M.; Rohsenow, Damaris J.; López, Steven R.; Hernández, Lynn; Caetano, Raul
2013-01-01
This study investigates the relationship between level of acculturation and acculturation stress, and the extent to which each predicts problems related to drinking. Hispanics who met criteria for hazardous drinking completed measures of acculturation, acculturation stress, and drinking problems. Sequential multiple regression was used to determine whether levels of self-reported acculturation stress predicted concurrent alcohol problems after controlling for the predictive value of accultura...
van Lang, NDJ; Ferdinand, RF; Oldehinkel, AJ; Ormel, J; Verhulst, FC
2005-01-01
This study investigated the concurrent validity of the DSM-IV scales Anxiety Problems and Affective Problems of the Youth Self-Report (YSR) in a community sample of Dutch young adolescents aged 10-12 years. We first examined the extent to which the YSR/DSM-IV scales reflect symptoms of DSM-IV anxiet
van Lang, NDJ; Ferdinand, RF; Oldehinkel, AJ; Ormel, J; Verhulst, FC
2005-01-01
This study investigated the concurrent validity of the DSM-IV scales Anxiety Problems and Affective Problems of the Youth Self-Report (YSR) in a community sample of Dutch young adolescents aged 10-12 years. We first examined the extent to which the YSR/DSM-IV scales reflect symptoms of DSM-IV
Occupational stress among nursing technicians and assistants: coping focused on the problem
Carla Araújo Bastos Teixeira
2015-04-01
Full Text Available Objective. To analyze the association between strategies used to cope with occupational stress that are focused on the problem wand the personal characteristics of nursing technicians and assistants. Methodology. This quantitative and correlational study was conducted in a large teaching hospital in the São Paulo State, Brazil, in 2013. A randomized sample with 310 participants (198 nursing assistants and 112 nursing technicians comprised the study population. Data were collected using a sociodemographic characteristics questionnaire and Scale of Ways of Coping with Problems. Data were submitted to univariate analysis, and variables with statistical significance (p<0.20 were submitted posteriorly in a multiple regression model. Results. Most employees were women (76.1% older than 40 years (67.7%, had nine to 11 years of formal education (73.5%, had a partner (58.7%, were Catholic (53.2%, and had children (74.5%. The final multiple regression model consisted of variable years of formal education and number of children. Conclusion. In this study, formal education and number of children were more strongly associated with a greater use of coping strategies focused on the problem. Such a strategy is related to minimal vulnerability to stress related to the working environment.
Validation of Bengali perceived stress scale among LGBT population.
Mozumder, Muhammad Kamruzzaman
2017-08-29
Lesbian, gay, bisexual and transgender (LGBT) population encounter more stressful life circumstances compared to general population. Perceived Stress Scale (PSS) can be a useful tool for measuring their stress. However, psychometric properties of PSS have never been tested on LGBT population. This cross sectional study employed a two-stage sampling strategy to collect data from 296 LGBT participants from six divisional districts of Bangladesh. Exploratory (EFA) and confirmatory factor analysis (CFA) were carried out on PSS 10 along with analysis of reliability and validity. EFA revealed a two-factor structure of PSS for LGBT population explaining 43.55% - 51.45% of total variance. This measurement model was supported by multiple fit indices during CFA. Acceptable Cronbach's alpha indicated internal consistency reliability and high correlations with Self Reporting Questionnaire 20 demonstrated construct validity of PSS 10 for LGBT population. This study provided evidence of satisfactory psychometric properties of Bengali PSS 10 in terms of factor structure, internal consistency and validity among LGBT population.
Scaling properties of weakly nonlinear coefficients in the Faraday problem.
Skeldon, A C; Porter, J
2011-07-01
Interesting and exotic surface wave patterns have regularly been observed in the Faraday experiment. Although symmetry arguments provide a qualitative explanation for the selection of some of these patterns (e.g., superlattices), quantitative analysis is hindered by mathematical difficulties inherent in a time-dependent, free-boundary Navier-Stokes problem. More tractable low viscosity approximations are available, but these do not necessarily capture the moderate viscosity regime of the most interesting experiments. Here we focus on weakly nonlinear behavior and compare the scaling results derived from symmetry arguments in the low viscosity limit with the computed coefficients of appropriate amplitude equations using both the full Navier-Stokes equations and a reduced set of partial differential equations due to Zhang and Vinãls. We find the range of viscosities over which one can expect "low viscosity" theories to hold. We also find that there is an optimal viscosity range for locating superlattice patterns experimentally-large enough that the region of parameters giving stable patterns is not impracticably small, yet not so large that crucial resonance effects are washed out. These results help explain some of the discrepancies between theory and experiment.
Feizi, Awat; Aliyari, Roqayeh; Roohafza, Hamidreza
2012-01-01
The present paper aimed at investigating the association between perceived stress and major life events stressors in Iranian general population. In a cross-sectional large-scale community-based study, 4583 people aged 19 and older, living in Isfahan, Iran, were investigated. Logistic quantile regression was used for modeling perceived stress, measured by GHQ questionnaire, as the bounded outcome (dependent), variable, and as a function of most important stressful life events, as the predictor variables, controlling for major lifestyle and sociodemographic factors. This model provides empirical evidence of the predictors' effects heterogeneity depending on individual location on the distribution of perceived stress. The results showed that among four stressful life events, family conflicts and social problems were more correlated with level of perceived stress. Higher levels of education were negatively associated with perceived stress and its coefficients monotonically decrease beyond the 30th percentile. Also, higher levels of physical activity were associated with perception of low levels of stress. The pattern of gender's coefficient over the majority of quantiles implied that females are more affected by stressors. Also high perceived stress was associated with low or middle levels of income. The results of current research suggested that in a developing society with high prevalence of stress, interventions targeted toward promoting financial and social equalities, social skills training, and healthy lifestyle may have the potential benefits for large parts of the population, most notably female and lower educated people.
Awat Feizi
2012-01-01
Full Text Available Objective. The present paper aimed at investigating the association between perceived stress and major life events stressors in Iranian general population. Methods. In a cross-sectional large-scale community-based study, 4583 people aged 19 and older, living in Isfahan, Iran, were investigated. Logistic quantile regression was used for modeling perceived stress, measured by GHQ questionnaire, as the bounded outcome (dependent, variable, and as a function of most important stressful life events, as the predictor variables, controlling for major lifestyle and sociodemographic factors. This model provides empirical evidence of the predictors’ effects heterogeneity depending on individual location on the distribution of perceived stress. Results. The results showed that among four stressful life events, family conflicts and social problems were more correlated with level of perceived stress. Higher levels of education were negatively associated with perceived stress and its coefficients monotonically decrease beyond the 30th percentile. Also, higher levels of physical activity were associated with perception of low levels of stress. The pattern of gender’s coefficient over the majority of quantiles implied that females are more affected by stressors. Also high perceived stress was associated with low or middle levels of income. Conclusions. The results of current research suggested that in a developing society with high prevalence of stress, interventions targeted toward promoting financial and social equalities, social skills training, and healthy lifestyle may have the potential benefits for large parts of the population, most notably female and lower educated people.
Samira S. Bamuhair
2015-01-01
Full Text Available Background. Medical education is rated as one of the most difficult trainings to endure. Throughout their undergraduate years, medical students face numerous stressors. Coping with these stressors requires access to a variety of resources, varying from personal strengths to social support. We aimed to explore the perceived stress, stressors, and coping strategies employed by medical students studying in a problem-based learning curriculum. Methodology. This is a cross-sectional study of randomly selected medical students that explored demographics, perceived stress scale, sources of stress, and coping strategies. Results. Of the 378 medical students that participated in the study, males were 59.3% and females 40.7%. Nearly 53% of the students often felt stressed, and a third felt that they could not cope with stress. Over 82% found studying stressful and 64.3% were not sleeping well. Half of the students reported low self-esteem. Perceived stress scores were statistically significantly high for specific stressors of studying in general, worrying about future, interpersonal conflict, and having low self-esteem. Coping strategies that were statistically significantly applied more often were blaming oneself and being self-critical, seeking advice and help from others, and finding comfort in religion. Female students were more stressed than males but they employ more coping strategies as well. Conclusions. Stress is very common among medical students. Most of the stressors are from coursework and interpersonal relationships. Low self-esteem coupled with self-blame and self-criticism is quite common.
Parenting Stress and Child Behavior Problems: A Transactional Relationship across Time
Neece, Cameron L.; Green, Shulamite A.; Baker, Bruce L.
2012-01-01
Parenting stress and child behavior problems have been posited to have a transactional effect on each other across development. However, few studies have tested this model empirically. The authors investigated the relationship between parenting stress and child behavior problems from ages 3 to 9 years old among 237 children, 144 of whom were…
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2011-01-01
The scaled boundary finite element method(SBFEM) is a semi-analytical numerical method,which models an analysis domain by a small number of large-sized subdomains and discretises subdomain boundaries only.In a subdomain,all fields of state variables including displacement,stress,velocity and acceleration are semi-analytical,and the kinetic energy,strain energy and energy error are all integrated semi-analytically.These advantages are taken in this study to develop a posteriori h-hierarchical adaptive SBFEM for transient elastodynamic problems using a mesh refinement procedure which subdivides subdomains.Because only a small number of subdomains are subdivided,mesh refinement is very simple and efficient,and mesh mapping to transfer state variables from an old mesh to a new one is also very simple but accurate.Two 2D examples with stress wave propagation were modelled.The results show that the developed method is capable of capturing propagation of steep stress regions and calculating accurate dynamic responses,using only a fraction of degrees of freedom required by adaptive finite element method.
Development and validation of the medical student stress scale in Korea.
Kim, Min Jeong; Park, Kwi Hwa; Yoo, Hyo Hyun; Park, Ie Byung; Yim, Jun
2014-09-01
Medical students experience various stresses that arise in a special environment. However, there is no specific stress scale for medical students with regard to their environment in Korea. Therefore, in this study, we developed and confirmed the validity of a stress scale for medical students in Korea. A draft version of the scale was developed on the basis of open-ended questionnaires from 97 medical students. The validity of the content of this scale was evaluated by three medical educationists. The scale was administered to 435 third and fourth grade medical students as the main survey. For our data, we performed an exploratory factor analysis and confirmatory factor analysis. We used Cronbach α index to determine internal consistency. Six factors with 40 items were extracted through the exploratory factor analysis: academic stress (9 items); clerkship stress (11 items); interpersonal stress (7 items); career stress (8 items); health-related stress (3 items); and financial stress (2 items). These factors showed a statistically significant correlation. The confirmatory factor analysis demonstrated a favorable RMSEA (0.053) and reasonable fit (CFI=0.847, TLI=0.833). Cronbach α values of the six factors ranged from 0.63 to 0.85. The medical student stress scale had a good model fit. It is a valid and reliable instrument in identifying stress in medical students and can be used in future studies. Also, the scale is expected to provide individual stress profiles for students to help them manage stress more effectively.
Cross-cultural validity of the masculine and Feminine Gender Role Stress scales
van Well, S; Kolk, AM; Arrindell, WA
The objective was to examine the usefulness of Dutch versions of the Masculine Gender Role Stress (MGRS; Eisler & Skidmore, 1987) Scale and the Feminine Gender Role Stress (Gillespie & Eisler, 1992) Scale in The Netherlands. Undergraduate students (N = 2,239) completed both gender role stress
AN IMPROVED DYNAMIC SUBGRID-SCALE STRESS MODEL
TANG Xue-ling; QIAN Zhong-dong; WU Yu-lin; LIU Shu-hong; YANG Fan
2004-01-01
According to modeling principle that a model must be more accurate if including more flow information, and based on the Cauchy-Helmholtz theorem and the Smagorinsky model, a second-order dynamic model with double dynamic coefficients was proposed by applying dimension analyses. The Subgrid-Scale (SGS) stress is a function of both strain-rate tensor and rotation-rate tensor. The SIMPLEC algorithm and staggering grid system was applied to give the solution of the discretized governing equations, and for the turbulent flow through a 90° bend, the distributions of velocity and pressure were achieved. The comparison between experimental data and simulation results at a Reynolds number 40000 shows a good agreement and implies that this model is practicable and credible.
Minority stress and sexual problems among African-American gay and bisexual men.
Zamboni, Brian D; Crawford, Isiaah
2007-08-01
Minority stress, such as racism and gay bashing, may be associated with sexual problems, but this notion has not been examined in the literature. African-American gay/bisexual men face a unique challenge in managing a double minority status, putting them at high risk for stress and sexual problems. This investigation examined ten predictors of sexual problems among 174 African-American gay/bisexual men. Covarying for age, a forward multiple regression analysis showed that the measures of self-esteem, male gender role stress, HIV prevention self-efficacy, and lifetime experiences with racial discrimination significantly added to the prediction of sexual problems. Gay bashing, psychiatric symptoms, low life satisfaction, and low social support were significantly correlated with sexual problems, but did not add to the prediction of sexual problems in the regression analysis. Mediation analyses showed that stress predicted psychiatric symptoms, which then predicted sexual problems. Sexual problems were not significantly related to HIV status, racial/ethnic identity, or gay identity. The findings from this study showed a relationship between experiences with racial and sexual discrimination and sexual problems while also providing support for mediation to illustrate how stress might cause sexual problems. Addressing minority stress in therapy may help minimize and treat sexual difficulties among minority gay/bisexual men.
Workplace stress in nursing workers from an emergency hospital: Job Stress Scale analysis.
Urbanetto, Janete de Souza; da Silva, Priscila Costa; Hoffmeister, Eveline; de Negri, Bianca Souza; da Costa, Bartira Ercília Pinheiro; Poli de Figueiredo, Carlos Eduardo
2011-01-01
This study identifies workplace stress according to the Job Stress Scale and associates it with socio-demographic and occupational variables of nursing workers from an emergency hospital. This is a cross-sectional study and data were collected through a questionnaire applied to 388 nursing professionals. Descriptive statistics were applied; univariate and multivariate analyses were performed. The results indicate there is a significant association with being a nursing technician or auxiliary, working in the position for more than 15 years, and having low social support, with 3.84, 2.25 and 4.79 times more chances of being placed in the 'high strain job' quadrant. The study reveals that aspects related to the workplace should be monitored by competent agencies in order to improve the quality of life of nursing workers.
Schlotz, Wolff; Yim, Ilona S.; Zoccola, Peggy M.; Jansen, Lars; Schulz, Peter
2011-01-01
There is accumulating evidence that individual differences in stress reactivity contribute to the risk for stress-related disease. However, the assessment of stress reactivity remains challenging, and there is a relative lack of questionnaires reliably assessing this construct. We here present the Perceived Stress Reactivity Scale (PSRS), a…
Allen, Jacqui; Annells, Merilyn
2009-04-01
To explore through literature review the appropriateness of three common tools for use by community nurses to screen war veteran and war widow(er) clients for depression, anxiety and post-traumatic stress disorder. War veterans and, to a lesser extent, war widow(er)s, are prone to mental health challenges, especially depression, anxiety and post-traumatic stress disorder. Community nurses do not accurately identify such people with depression and related disorders although they are well positioned to do so. The use of valid and reliable self-report tools is one method of improving nurses' identification of people with actual or potential mental health difficulties for referral to a general practitioner or mental health practitioner for diagnostic assessment and treatment. The Geriatric Depression Scale, Depression Anxiety Stress Scales and Post-traumatic Stress Disorder Checklist are frequently recommended for mental health screening but the appropriateness of using the tools for screening war veteran and war widow(er) community nursing clients who are often aged and have functional impairment, is unknown. Systematic review. Current literature informs that the Geriatric Depression Scale accurately predicts a diagnosis of depression in community nursing cohorts. The three Depression Anxiety Stress Scales subscales of depression, anxiety and stress are valid; however, no studies were identified that compared the performance of the Depression Anxiety Stress Scales in predicting diagnoses of depression or anxiety. The Post-traumatic Stress Disorder Checklist predicts post-traumatic stress disorder in community cohorts although no studies meeting the selection criteria included male participants. This review provides recommendations for the use of the Geriatric Depression Scale, Depression Anxiety Stress Scales and The Post-traumatic Stress Disorder Checklist based on examination of the published evidence for the application of these screening tools in samples
Segou, M.; Parsons, T.
2014-06-01
Main shocks are calculated to cast stress shadows across broad areas where aftershocks occur. Thus, a key problem with stress-based operational forecasts is that they can badly underestimate aftershock occurrence in the shadows. We examine the performance of two physics-based earthquake forecast models (Coulomb rate/state (CRS)) based on Coulomb stress changes and a rate-and-state friction law for their predictive power on the 1989 Mw = 6.9 Loma Prieta aftershock sequence. The CRS-1 model considers the stress perturbations associated with the main shock rupture only, whereas CRS-2 uses an updated stress field with stresses imparted by M ≥ 3.5 aftershocks. Including secondary triggering effects slightly improves predictability, but physics-based models still underestimate aftershock rates in locations of initial negative stress changes. Furthermore, CRS-2 does not explain aftershock occurrence where secondary stress changes enhance the initial stress shadow. Predicting earthquake occurrence in calculated stress shadow zones remains a challenge for stress-based forecasts, and additional triggering mechanisms must be invoked.
Surrogate-based modeling and dimension reduction techniques for multi-scale mechanics problems
Wei Shyy; Young-Chang Cho; Wenbo Du; Amit Gupta; Chien-Chou Tseng; Ann Marie Sastry
2011-01-01
Successful modeling and/or design of engineering systems often requires one to address the impact of multiple “design variables” on the prescribed outcome.There are often multiple,competing objectives based on which we assess the outcome of optimization.Since accurate,high fidelity models are typically time consuming and computationally expensive,comprehensive evaluations can be conducted only if an efficient framework is available.Furthermore,informed decisions of the model/hardware's overall performance rely on an adequate understanding of the global,not local,sensitivity of the individual design variables on the objectives.The surrogate-based approach,which involves approximating the objectives as continuous functions of design variables from limited data,offers a rational framework to reduce the number of important input variables,i.e.,the dimension of a design or modeling space.In this paper,we review the fundamental issues that arise in surrogate-based analysis and optimization,highlighting concepts,methods,techniques,as well as modeling implications for mechanics problems.To aid the discussions of the issues involved,we summarize recent efforts in investigating cryogenic cavitating flows,active flow control based on dielectric barrier discharge concepts,and lithium (Li)-ion batteries.It is also stressed that many multi-scale mechanics problems can naturally benefit from the surrogate approach for “scale bridging.”
Development and Validation of Students' Stress Rating Scale (SSRS)
Balamurugan, M.; Kumaran, D.
2008-01-01
Each and every person is under the grip of stress. Starting from a two-year infant to an adult, stress takes an entry in different forms but it alters the normal functioning of a person. One cannot eliminate stress but can reduce stress in their life. The stressors are normative demands and critical life events. Normative stressors include…
Mathematical programming methods for large-scale topology optimization problems
Rojas Labanda, Susana
, and at the same time, reduce the number of function evaluations. Nonlinear optimization methods, such as sequential quadratic programming and interior point solvers, have almost not been embraced by the topology optimization community. Thus, this work is focused on the introduction of this kind of second......This thesis investigates new optimization methods for structural topology optimization problems. The aim of topology optimization is finding the optimal design of a structure. The physical problem is modelled as a nonlinear optimization problem. This powerful tool was initially developed...... for the classical minimum compliance problem. Two of the state-of-the-art optimization algorithms are investigated and implemented for this structural topology optimization problem. A Sequential Quadratic Programming (TopSQP) and an interior point method (TopIP) are developed exploiting the specific mathematical...
Symplectic solution for three dimensional couple stress problem and its variational principle
Jianhui Luo; Guangdong Liu; Wanxie Zhong
2005-01-01
A new state vector is presented for symplectic solution to three dimensional couple stress problem. Without relying on the analogy relationship, the dual PDEs of couple stress problem are derived by a new state vector. The duality solution methodology in a new form is thus extended to three dimensional couple stress. A new symplectic orthonormality relationship is proved. The symplectic solution to couple stress theory based a new state vector is more accordant with the custom of classical elasticity and is more convenient to process boundary conditions. A Hamilton mixed energy variational principle is derived by the integral method.
Understanding hydraulic fracturing: a multi-scale problem.
Hyman, J D; Jiménez-Martínez, J; Viswanathan, H S; Carey, J W; Porter, M L; Rougier, E; Karra, S; Kang, Q; Frash, L; Chen, L; Lei, Z; O'Malley, D; Makedonska, N
2016-10-13
Despite the impact that hydraulic fracturing has had on the energy sector, the physical mechanisms that control its efficiency and environmental impacts remain poorly understood in part because the length scales involved range from nanometres to kilometres. We characterize flow and transport in shale formations across and between these scales using integrated computational, theoretical and experimental efforts/methods. At the field scale, we use discrete fracture network modelling to simulate production of a hydraulically fractured well from a fracture network that is based on the site characterization of a shale gas reservoir. At the core scale, we use triaxial fracture experiments and a finite-discrete element model to study dynamic fracture/crack propagation in low permeability shale. We use lattice Boltzmann pore-scale simulations and microfluidic experiments in both synthetic and shale rock micromodels to study pore-scale flow and transport phenomena, including multi-phase flow and fluids mixing. A mechanistic description and integration of these multiple scales is required for accurate predictions of production and the eventual optimization of hydrocarbon extraction from unconventional reservoirs. Finally, we discuss the potential of CO2 as an alternative working fluid, both in fracturing and re-stimulating activities, beyond its environmental advantages.This article is part of the themed issue 'Energy and the subsurface'.
Confirmatory factor analysis of the portuguese Depression Anxiety Stress Scales-21
Apóstolo,João Luís Alves; Tanner,Barry Allen; Arfken,Cynthia Lee
2012-01-01
To determine which of three published models best characterizes the factor structure of the Portuguese version of the Depression Anxiety Stress Scales-21 and to assess its validity and reliability. Confirmatory factor analysis of Depression Anxiety and Stress Scale-21 for 1,297 adult, primary care outpatients (66.7% female, Mage = 48.57 years) comparing 3 models. The relationship between the Depression Anxiety Stress Scales-21 and the Positive and Negative Affect Schedule was analyzed. The co...
Scaling Problems for Wave Propagation in Layered Systems. Volume 1
1989-09-01
Spring, Maryland. 20. Shigley , J.E. 1977. Mechanical Engineering Design, 3rd Edition. McGraw-Hill Book Company, Inc., New York. 21. Juvinall, Robert C...41(7): 984-996. A.2 Roark, R.J., and Young, E. M., 1975. Formulas for Stress and Strain. Mcgraw-Hill Book Co. New York. A.3 Shigley , J.E. 1977
Modelling, Transformations, and Scaling Decisions in Constrained Optimization Problems
1976-03-01
applied nonlinear programming /2§/ , and are given in Appendix A of this thesis along with the original source. They will be referred to as Himmelblau ...j (19) 44 Therefore z=v . In x. can be replaced in the formulation by: 3 i z=Y i "Yj (20) Himmelblau problem 16 has numerous cross product terms in...optimum point, and thus are not recommended. 69 APPENDIX A Test Problems Used with GRG and SUMT Codes A. HIMMELBLAU PROBLEM 16 Source: J.D. Pearson
Liu, Li; Wang, Meifang
2015-02-01
This study examined the mediating effect of parents' psychological aggression in the relationship between parenting stress and children's internalizing (anxiety/depression, withdrawal) and externalizing (aggression, delinquency) problem behaviors 1 year later. Using a sample of 311 intact 2-parent Chinese families with preschoolers, findings revealed that maternal parenting stress had direct effects on children's internalizing and externalizing problem behavior and indirect effects through maternal psychological aggression. However, neither direct nor indirect effects of fathers' parenting stress on children's internalizing and externalizing problem behavior were found. The findings highlight the importance of simultaneously studying the effects of both mothers' and fathers' parenting on their children within a family systems framework.
Two-scale meshes in quasilinear discretized problems of computational mechanics
Jarošová, P.; Vala, J.
2016-06-01
Some problems of continuum mechanics, as the analysis of crack formation in the cohesive zone modelling, require (at least) two-scale numerical approach to finite element (or volume, difference, etc.) computations: i) at the macro-scale for a whole (nearly elastic, partially damaged) body and ii) at the micro-scale near the crack (a new interior surface). The paper presents an always convergent procedure handling overlapping two-scale meshes for such model problems, open to generalizations in many directions.
EIGENVALUE PROBLEM OF A LARGE SCALE INDEFINITE GYROSCOPIC DYNAMIC SYSTEM
SUI Yong-feng; ZHONG Wan-xie
2006-01-01
Gyroscopic dynamic system can be introduced to Hamiltonian system. Based on an adjoint symplectic subspace iteration method of Hamiltonian gyroscopic system,an adjoint symplectic subspace iteration method of indefinite Hamiltonian function gyroscopic system was proposed to solve the eigenvalue problem of indefinite Hamiltonian function gyroscopic system. The character that the eigenvalues of Hamiltonian gyroscopic system are only pure imaginary or zero was used. The eigenvalues that Hamiltonian function is negative can be separated so that the eigenvalue problem of positive definite Hamiltonian function system was presented, and an adjoint symplectic subspace iteration method of positive definite Hamiltonian function system was used to solve the separated eigenvalue problem. Therefore, the eigenvalue problem of indefinite Hamiltonian function gyroscopic system was solved, and two numerical examples were given to demonstrate that the eigensolutions converge exactly.
Evelina Viduoliene
2013-06-01
Full Text Available Purpose: evaluate 1 whether child’s externalizing problems increase or decrease within 12 months period; 2 the change of externalizing problems with respect to child gender and age, and 3 which maternal parenting stress factors and family sociodemographic characteristics can predict the increase and decrease of child’s externalizing problems. Design/methodology/approach: participants were evaluated 2 times (with the interval of 12 months with the Parenting Stress Index (Abidin, 1990 and Child Behavior Checklist 1.5−5 years (Achenbach, Rescorla, 2000 questionnaires. Findings: Child’s externalizing problems decreased within 12 months period. There were no effects of child’s age, gender and age*gender interaction on externalizing problems change within 12 months period. Higher initial level and more negative change within 12 months period of maternal parenting stress related to child characteristics, more stressful events in family life predicted the increase of child’s externalizing problems. Research limitations/implications: maternal parenting stress and child’s externalizing problems are related and may influence each other simultaneously. Child’s externalizing problems decrease within one year period in overall 2−5 years old children group. The change of child’s aggressive behavior and hyperactivity, distractibility should be evaluated individually, separately from each other. Practical implications: maternal parenting stress and child’s behavior problems are closely related to each other, it may be meaningful organize intervention for mothers in order to prevent child’s externalizing problems increase. Keywords: maternal parenting stress, externalizing problems, childhood, toddlerhood, longitudinal research. Research type: research paper.
Psychometric analysis of the Ten-Item Perceived Stress Scale.
Taylor, John M
2015-03-01
Although the 10-item Perceived Stress Scale (PSS-10) is a popular measure, a review of the literature reveals 3 significant gaps: (a) There is some debate as to whether a 1- or a 2-factor model best describes the relationships among the PSS-10 items, (b) little information is available on the performance of the items on the scale, and (c) it is unclear whether PSS-10 scores are subject to gender bias. These gaps were addressed in this study using a sample of 1,236 adults from the National Survey of Midlife Development in the United States II. Based on self-identification, participants were 56.31% female, 77% White, 17.31% Black and/or African American, and the average age was 54.48 years (SD = 11.69). Findings from an ordinal confirmatory factor analysis suggested the relationships among the items are best described by an oblique 2-factor model. Item analysis using the graded response model provided no evidence of item misfit and indicated both subscales have a wide estimation range. Although t tests revealed a significant difference between the means of males and females on the Perceived Helplessness Subscale (t = 4.001, df = 1234, p < .001), measurement invariance tests suggest that PSS-10 scores may not be substantially affected by gender bias. Overall, the findings suggest that inferences made using PSS-10 scores are valid. However, this study calls into question inferences where the multidimensionality of the PSS-10 is ignored. 2015 APA, all rights reserved
Psychometric Evaluation of the Wang Pregnancy Stress Scale: Revised for Taiwanese Women.
Wang, Janet F; Billings, Anthony A
2015-01-01
Develop and assess psychometric properties of the Wang Pregnancy Stress Scale for measuring stress among pregnant women in Taiwan. Data were collected in 3 obstetric and gynecological clinics in Taiwan; 485 pregnant women participated in this study. We used exploratory factor analysis and internal consistency reliability was measured using Cronbach's alpha. A 4-factor structure emerged for the Wang Pregnancy Stress Scale. The internal reliability of the scale as measured by Cronbach's alpha was .898, with standardized alpha .905. The Wang Pregnancy Stress Scale has high reliability and validity in measuring pregnancy stress that would allow nurses or health care workers to measure women's stress levels during pregnancy. Nurses can use the assessed pregnancy stress to alter intervention of care for their pregnant clients.
Psychosocial problems of women with stress urinary incontinence
Grażyna Stadnicka
2015-09-01
Full Text Available Objective. The aim of the study was evaluation of the influence of stress urinary incontinence on women’s quality of life. Material and method. The study covered 275 women between 30–65 years of age. The study was conducted using the following tools: [i]Gaudenz [/i]Questionnaire, [i]King’s Health Questionnaire[/i] (KHQ, [i]Female Sexual Function Index[/i] (FIFI Questionnaire, and a questionnaire devised by the authors of the study. Results. The study shows that the disease has a negative effect on evaluation of the quality of thee women’s lives. The symptoms of stress urinary incontinence had a significant influence on the feeling of emotional comfort, social and professional activity of the surveyed women – respectively p= 0.000; p=0.000; p=0.000. Nearly every third woman (28.7% felt great mental discomfort related to the disease symptoms, 31.7% a considerable discomfort, 33.1% a moderate, and very few women (6.5 % claimed that the disease had a minimal effect on their emotional state. About two-thirds of the surveyed women (68.7% were sexually active, and the remaining 31.3% declared the lack of sexual intercourse. Conclusions. The occurrence of stress urinary incontinence symptoms affects the quality of life of women, especially their mental state and interpersonal contacts. Most women with the symptoms of stress urinary incontinence fulfill their sexual needs; however, many of them do not feel complete satisfaction with their sex life.
["Stress" ulcer--a problem of the general surgeon].
Danelisen, D; Zigić, B; Rac, S
1982-01-01
Contemporary way of living accompanied by everday frustrations, a frequent use of medicaments, an easy application of corticosteroids, complexity of an opeation, so as an increased incidence of polytraumas --those are the factors responsible for an increasing rate of stress ulcus. The rate of 54 verified stress ulcus in the period from 1969-1979 in Regional Medical Centre of Banja Luka, at Surgical Department, are very often indicative of this disease. Thirty eight operatively treated patients are indicative of severity of this disease. The authors are reporting their experiences in resolving this disease by method of vagotomy with partial gastrectomy in comparison to simple sutures of acutely developed ulcus in addition to PS vagotomy. Perforation, which has, usually, been bigger than the chronic ulcus, we had in 31 cases. If the reports of the world authors are reliable, perforation occurs in 5% of cases only, therefore it is clear how many such conditions has remained undetected or treated under various other "working" diagnoses: (DIC, consumer coagulopathy, fibrinolysis, etc.". The stress ulcus is the disease which is a danger to any patient at Surgical Department.
Bayani, Ali Asghar
2010-08-01
The internal consistency, test-retest reliability, and construct validity of the Farsi version of the Depression Anxiety Stress Scales were examined, with a sample of 306 undergraduate students (123 men, 183 women) ranging from 18 to 51 years of age (M age = 25.4, SD = 6.1). Participants completed the Satisfaction with Life Scale, Rosenberg Self-esteem Scale, and the Depression Anxiety Stress Scales. The findings confirmed the preliminary reliabilities and preliminary construct validity of the Farsi translation of the Depression Anxiety Stress Scales.
Yi Yang; Jike Liu; Chengwu Cai
2008-01-01
The stress concentration problem in structures with a circular or elliptic hole can be investigated by analytical methods.For the problem with a rectangular hole,only approximate results are derived.This paper deduces the analytical solutions to the stress concentration problem in plates with a rectangular hole under biaxial tensions.By using the U-transformation technique and the finite element method,the analytical displacement solutions of the finite element equations are derived in the series form.Therefore,the stress concentration can then be discussed easily and conveniently.For plate problem the bilinear rectangular element with four nodes is taken as an example to demonstrate the applicability of the proposed method.The stress concentration factors for various ratios of height to width of the hole are obtained.
Dalia Bedewy; Adel Gabriel
2015-01-01
The development of a scale to measure perceived sources of academic stress among university students. Based on empirical evidence and recent literature review, we developed an 18-item scale to measure perceptions of academic stress and its sources. Experts (n = 12) participated in the content validation process of the instrument before it was administered to (n = 100) students. The developed instrument has internal consistency reliability of 0.7 (Cronbach’s alpha), there was evidence for cont...
Educational Benefit-Cost Analysis and the Problem of Scale.
Welty, Gordon A.
Benefit-cost analysis consists of establishing ratios of benefits to costs for a set of project variants. The decision rule is to select that project variant where the ratio is a maximum. This paper argues that specification and estimation errors can contribute to findings for large-scale systems of benefit-cost ratios approximating zero. The…
Newton Methods for Large Scale Problems in Machine Learning
Hansen, Samantha Leigh
2014-01-01
The focus of this thesis is on practical ways of designing optimization algorithms for minimizing large-scale nonlinear functions with applications in machine learning. Chapter 1 introduces the overarching ideas in the thesis. Chapters 2 and 3 are geared towards supervised machine learning applications that involve minimizing a sum of loss…
Newton Methods for Large Scale Problems in Machine Learning
Hansen, Samantha Leigh
2014-01-01
The focus of this thesis is on practical ways of designing optimization algorithms for minimizing large-scale nonlinear functions with applications in machine learning. Chapter 1 introduces the overarching ideas in the thesis. Chapters 2 and 3 are geared towards supervised machine learning applications that involve minimizing a sum of loss…
2014-01-01
Background: Parents of children with developmental problems are always bearing a load of stress. The aim of this study is to compare the stress in mothers of children with different disabilities to each other, considering their demographic background. Materials and Methods: This was a cross-sectional study conducted in Isfahan, Iran during 2012 on 285 mothers of 6-12 years old children with chronic physical disease, psychological disorder, and sensory-motor and mental problems. Abedin's paren...
Brack, Gregory; And Others
1992-01-01
Examined effects of stress on depression in female commuter college students (n=106). Results indicate that problem-solving confidence was important moderating variable and suggest that perception of long-term stress directly affects current depression level. Positive long-term experiences seemed to moderate subsequent negative experiences that…
Posttraumatic Stress Disorder and Intimate Relationship Problems: A Meta-Analysis
Taft, Casey T.; Watkins, Laura E.; Stafford, Jane; Street, Amy E.; Monson, Candice M.
2011-01-01
Objective: The authors conducted a meta-analysis of empirical studies investigating associations between indices of posttraumatic stress disorder (PTSD) and intimate relationship problems to empirically synthesize this literature. Method: A literature search using PsycINFO, Medline, Published International Literature on Traumatic Stress (PILOTS),…
Pro-Social Behaviour and Behaviour Problems Independently Predict Maternal Stress
Beck, Alexandra; Hastings, Richard; Daley, Dave; Stevenson, Jim
2004-01-01
Parents of children with intellectual and developmental disabilities generally report more stress than other parents. Child behavioural features, and specifically their behaviour problems, have been shown to account for some of the variation in parents' experience of stress. However, there has been no exploration of whether the child's pro-social…
Verkleij, Marieke; van de Griendt, Erik-Jonas; Colland, Vivian; van Loey, Nancy; Beelen, Anita; Geenen, Rinie
2015-09-01
Our study examined parenting stress and its association with behavioral problems and disease severity in children with problematic severe asthma. Research participants were 93 children (mean age 13.4 ± 2.7 years) and their parents (86 mothers, 59 fathers). As compared to reference groups analyzed in previous research, scores on the Parenting Stress Index in mothers and fathers of the children with problematic severe asthma were low. Higher parenting stress was associated with higher levels of internalizing and externalizing behavioral problems in children (Child Behavior Checklist). Higher parenting stress in mothers was also associated with higher airway inflammation (FeNO). Thus, although parenting stress was suggested to be low in this group, higher parenting stress, especially in the mother, is associated with more airway inflammation and greater child behavioral problems. This indicates the importance of focusing care in this group on all possible sources of problems, i.e., disease exacerbations and behavioral problems in the child as well as parenting stress.
A probabilistic solution of robust H∞ control problem with scaled matrices
Xie, R.; Gong, J. Y.
2016-07-01
This paper addresses the robust H∞ control problem with scaled matrices. It is difficult to find a global optimal solution for this non-convex optimisation problem. A probabilistic solution, which can achieve globally optimal robust performance within any pre-specified tolerance, is obtained by using the proposed method based on randomised algorithm. In the proposed method, the scaled H∞ control problem is divided into two parts: (1) assume the scaled matrices be random variables, the scaled H∞ control problem is converted to a convex optimisation problem for the fixed sample of the scaled matrix and a optimal solution corresponding to the fixed sample is obtained; (2) a probabilistic optimal solution is obtained by using the randomised algorithm based on a finite number N optimal solutions, which are obtained in part (1). The analysis shows that the worst case complexity of proposed method is a polynomial.
Xiushan Sun; Lixin Huang; Yinghua Liu; Zhangzhi Cen; Keren Wang
2005-01-01
Both the orthotropy and the stress concentration are common issues in modern structural engineering. This paper introduces the boundary element method (BEM) into the elastic and elastoplastic analyses for 2D orthotropic media with stress concentration. The discretized boundary element formulations are established, and the stress formulae as well as the fundamental solutions are derived in matrix notations. The numerical procedures are proposed to analyze both elastic and elastoplastic problems of2D orthotropic media with stress concentration. To obtain more precise stress values with fewer elements, the quadratic isoparametric element formulation is adopted in the boundary discretization and numerical procedures. Numerical examples show that there are significant stress concentrations and different elastoplastic behaviors in some orthotropic media, and some of the computational results are compared with other solutions.Good agreements are also observed, which demonstrates the efficiency and reliability of the present BEM in the stress concentration analysis for orthotropic media.
Awat Feizi
2014-01-01
Full Text Available Background: Parents of children with developmental problems are always bearing a load of stress. The aim of this study is to compare the stress in mothers of children with different disabilities to each other, considering their demographic background. Materials and Methods: This was a cross-sectional study conducted in Isfahan, Iran during 2012 on 285 mothers of 6-12 years old children with chronic physical disease, psychological disorder, and sensory-motor and mental problems. Abedin′s parenting stress questionnaire was used and obtained data were analyzed using multivariate analysis of variance or covariance as appropriate. Results: Mothers of children with sensory-motor mental and chronic physical problems experience more stress than mothers of children with psychological disorders (P < 0.05. The stress score of mothers of children with psychological disorders was lower than the other two groups. Also there was a significant difference between the score of mothers of children with chronic physical problems and mothers of children with psychological disorders regarding parent-child dysfunctional interaction (P < 0.01. A significant difference was observed in terms of stress among mothers of children with sensory-motor mental problems with different number of children (P < 0.05; also mothers of children with chronic physical problems in different levels of education have experienced different levels of parenting stress (P < 0.05 Conclusion: Due to high level of parenting stress among our studied samples, special education and early intervention are needed for parents in our study population in order to deepening their diagnostic knowledge and professional consultation on stress management
Feizi, Awat; Najmi, Badroddin; Salesi, Aseih; Chorami, Maryam; Hoveidafar, Rezvan
2014-01-01
Background: Parents of children with developmental problems are always bearing a load of stress. The aim of this study is to compare the stress in mothers of children with different disabilities to each other, considering their demographic background. Materials and Methods: This was a cross-sectional study conducted in Isfahan, Iran during 2012 on 285 mothers of 6-12 years old children with chronic physical disease, psychological disorder, and sensory-motor and mental problems. Abedin's parenting stress questionnaire was used and obtained data were analyzed using multivariate analysis of variance or covariance as appropriate. Results: Mothers of children with sensory-motor mental and chronic physical problems experience more stress than mothers of children with psychological disorders (P < 0.05). The stress score of mothers of children with psychological disorders was lower than the other two groups. Also there was a significant difference between the score of mothers of children with chronic physical problems and mothers of children with psychological disorders regarding parent-child dysfunctional interaction (P < 0.01). A significant difference was observed in terms of stress among mothers of children with sensory-motor mental problems with different number of children (P < 0.05); also mothers of children with chronic physical problems in different levels of education have experienced different levels of parenting stress (P < 0.05) Conclusion: Due to high level of parenting stress among our studied samples, special education and early intervention are needed for parents in our study population in order to deepening their diagnostic knowledge and professional consultation on stress management PMID:24778669
Marshall, Margarita B.; Bagby, R. Michael
2006-01-01
The incremental validity and clinical utility of the recently developed Minnesota Multiphasic Personality Inventory-2 (MMPI-2) Infrequency Posttraumatic Stress Disorder Scale (Fptsd) was examined in relation to the family of MMPI-2 F scales in distinguishing feigned post-traumatic stress disorder (PTSD) from disability claimants with PTSD.…
LaGasse, Linda L.; Conradt, Elisabeth; Karalunas, Sarah L.; Dansereau, Lynne M.; Butner, Jonathan E.; Shankaran, Seetha; Bada, Henrietta; Bauer, Charles R.; Whitaker, Toni M.; Lester, Barry M.
2016-01-01
Developmental psychopathologists face the difficult task of identifying the environmental conditions that may contribute to early childhood behavior problems. Highly stressed caregivers can exacerbate behavior problems, while children with behavior problems may make parenting more difficult and increase caregiver stress. Unknown is: (1) how these transactions originate, (2) whether they persist over time to contribute to the development of problem behavior and (3) what role resilience factors, such as child executive functioning, may play in mitigating the development of problem behavior. In the present study, transactional relations between caregiving stress, executive functioning, and behavior problems were examined in a sample of 1,388 children with prenatal drug exposures at three developmental time points: early childhood (birth-age 5), middle childhood (ages 6 to 9), and early adolescence (ages 10 to 13). Transactional relations differed between caregiving stress and internalizing versus externalizing behavior. Targeting executive functioning in evidence-based interventions for children with prenatal substance exposure who present with internalizing problems and treating caregiving psychopathology, depression, and parenting stress in early childhood may be particularly important for children presenting with internalizing behavior. PMID:27427803
Lagasse, Linda L; Conradt, Elisabeth; Karalunas, Sarah L; Dansereau, Lynne M; Butner, Jonathan E; Shankaran, Seetha; Bada, Henrietta; Bauer, Charles R; Whitaker, Toni M; Lester, Barry M
2016-08-01
Developmental psychopathologists face the difficult task of identifying the environmental conditions that may contribute to early childhood behavior problems. Highly stressed caregivers can exacerbate behavior problems, while children with behavior problems may make parenting more difficult and increase caregiver stress. Unknown is: (a) how these transactions originate, (b) whether they persist over time to contribute to the development of problem behavior and (c) what role resilience factors, such as child executive functioning, may play in mitigating the development of problem behavior. In the present study, transactional relations between caregiving stress, executive functioning, and behavior problems were examined in a sample of 1,388 children with prenatal drug exposures at three developmental time points: early childhood (birth to age 5), middle childhood (ages 6 to 9), and early adolescence (ages 10 to 13). Transactional relations differed between caregiving stress and internalizing versus externalizing behavior. Targeting executive functioning in evidence-based interventions for children with prenatal substance exposure who present with internalizing problems and treating caregiving psychopathology, depression, and parenting stress in early childhood may be particularly important for children presenting with internalizing behavior.
Problem Gambling Family Impacts: Development of the Problem Gambling Family Impact Scale.
Dowling, N A; Suomi, A; Jackson, A C; Lavis, T
2016-09-01
Although family members of problem gamblers frequently present to treatment services, problem gambling family impacts are under-researched. The most commonly endorsed items on a new measure of gambling-related family impacts [Problem Gambling Family Impact Measure (PG-FIM: Problem Gambler version)] by 212 treatment-seeking problem gamblers included trust (62.5 %), anger (61.8 %), depression or sadness (58.7 %), anxiety (57.7 %), distress due to gambling-related absences (56.1 %), reduced quality time (52.4 %), and communication breakdowns (52.4 %). The PG-FIM (Problem Gambler version) was comprised of three factors: (1) financial impacts, (2) increased responsibility impacts, and (3) psychosocial impacts with good psychometric properties. Younger, more impulsive, non-electronic gaming machine (EGM) gamblers who had more severe gambling problems reported more financial impacts; non-EGM gamblers with poorer general health reported more increased responsibility impacts; and more impulsive non-EGM gamblers with more psychological distress and higher gambling severity reported more psychosocial impacts. The findings have implications for the development of interventions for the family members of problem gamblers.
Profiles of Observed Infant Anger Predict Preschool Behavior Problems: Moderation by Life Stress
Brooker, Rebecca J.; Buss, Kristin A.; Lemery-Chalfant, Kathryn; Aksan, Nazan; Davidson, Richard J.; Goldsmith, H. Hill
2014-01-01
Using both traditional composites and novel profiles of anger, we examined associations between infant anger and preschool behavior problems in a large, longitudinal data set (N = 966). We also tested the role of life stress as a moderator of the link between early anger and the development of behavior problems. Although traditional measures of…
Bedewy, Dalia; Gabriel, Adel
2015-07-01
The development of a scale to measure perceived sources of academic stress among university students. Based on empirical evidence and recent literature review, we developed an 18-item scale to measure perceptions of academic stress and its sources. Experts (n = 12) participated in the content validation process of the instrument before it was administered to (n = 100) students. The developed instrument has internal consistency reliability of 0.7 (Cronbach's alpha), there was evidence for content validity, and factor analysis resulted in four correlated and theoretically meaningful factors. We developed and tested a scale to measure academic stress and its sources. This scale takes 5 minutes to complete.
Dalia Bedewy
2015-07-01
Full Text Available The development of a scale to measure perceived sources of academic stress among university students. Based on empirical evidence and recent literature review, we developed an 18-item scale to measure perceptions of academic stress and its sources. Experts (n = 12 participated in the content validation process of the instrument before it was administered to (n = 100 students. The developed instrument has internal consistency reliability of 0.7 (Cronbach’s alpha, there was evidence for content validity, and factor analysis resulted in four correlated and theoretically meaningful factors. We developed and tested a scale to measure academic stress and its sources. This scale takes 5 minutes to complete.
Parental problem-solving skills, stress, and dietary compliance in phenylketonuria.
Fehrenbach, A M; Peterson, L
1989-04-01
Parents of 30 children with phenylketonuria (PKU) who were classified as being in good dietary control (compliant, measured as within the medically acceptable range of blood phenylalanine levels of 2-10 mg) or poor dietary control (noncompliant, measured as either below or above medically acceptable 2-10 mg blood phenylalanine levels) engaged in verbal and written problem-solving situations under conditions of both high and low time-pressure induced stress. Overall, compliant parents gave higher quality verbal and written problem-solving solutions than noncompliant parents. Stress reduced the quality of problem solving in both compliant and noncompliant parents, but even under high stress, compliant parents demonstrated better problem-solving abilities than noncompliant parents. The potential importance of these findings for preventive intervention in PKU families is discussed.
Zheng, Weixiong
2016-01-01
In this paper, we present an accurate and robust scaling operator based on material optical thickness (OT) for the least-squares spherical harmonics (LSP$_N$) method for solving neutron transport problems. LSP$_N$ without proper scaling is known to be erroneous in highly scattering medium, if the optical thickness of the material is large. A previously presented scaling developed by Manteuffel, et al.\\ does improve the accuracy of LSP$_N$, in problems where the material is optically thick. With the method, however, essentially no scaling is applied in optically thin materials, which can lead to an erroneous solution with presence of highly scattering medium. Another scaling approach, called the reciprocal-removal (RR) scaled LSP$_N$, which is equivalent to the self-adjoint angular flux (SAAF) equation, has numerical issues in highly-scattering materials due to a singular weighting. We propose a scaling based on optical thickness that improves the solution in optically thick media while avoiding the singularit...
Second-order perturbation theory: Problems on large scales
Pound, Adam
2015-11-01
In general-relativistic perturbation theory, a point mass accelerates away from geodesic motion due to its gravitational self-force. Because the self-force is small, one can often approximate the motion as geodesic. However, it is well known that self-force effects accumulate over time, making the geodesic approximation fail on long time scales. It is less well known that this failure at large times translates to a failure at large distances as well. At second perturbative order, two large-distance pathologies arise: spurious secular growth and infrared-divergent retarded integrals. Both stand in the way of practical computations of second-order self-force effects. Utilizing a simple flat-space scalar toy model, I develop methods to overcome these obstacles. The secular growth is tamed with a multiscale expansion that captures the system's slow evolution. The divergent integrals are eliminated by matching to the correct retarded solution at large distances. I also show how to extract conservative self-force effects by taking local-in-time "snapshots" of the global solution. These methods are readily adaptable to the physically relevant case of a point mass orbiting a black hole.
Enabling High Performance Large Scale Dense Problems through KBLAS
Abdelfattah, Ahmad
2014-05-04
KBLAS (KAUST BLAS) is a small library that provides highly optimized BLAS routines on systems accelerated with GPUs. KBLAS is entirely written in CUDA C, and targets NVIDIA GPUs with compute capability 2.0 (Fermi) or higher. The current focus is on level-2 BLAS routines, namely the general matrix vector multiplication (GEMV) kernel, and the symmetric/hermitian matrix vector multiplication (SYMV/HEMV) kernel. KBLAS provides these two kernels in all four precisions (s, d, c, and z), with support to multi-GPU systems. Through advanced optimization techniques that target latency hiding and pushing memory bandwidth to the limit, KBLAS outperforms state-of-the-art kernels by 20-90% improvement. Competitors include CUBLAS-5.5, MAGMABLAS-1.4.0, and CULAR17. The SYMV/HEMV kernel from KBLAS has been adopted by NVIDIA, and should appear in CUBLAS-6.0. KBLAS has been used in large scale simulations of multi-object adaptive optics.
Health problems and stress in Information Technology and Business Process Outsourcing employees
Padma, V.; Anand, N. N.; Gurukul, S. M. G. Swaminatha; Javid, S. M. A. Syed Mohammed; Prasad, Arun; Arun, S.
2015-01-01
Stress is high in software profession because of their nature of work, target, achievements, night shift, over work load. 1. To study the demographic profile of the employees. 2. To access the level of job stress and quality of life of the respondents. 3. To study in detail the health problems of the employees. All employees working in IT and BPO industry for more than two years were included into the study. A detailed questionnaire of around 1000 IT and BPO employees including their personal details, stress score by Holmes and Rahe to assess the level of stress and master health checkup profile were taken and the results were analysed. Around 56% had musculoskeletal symptoms. 22% had newly diagnosed hypertension,10% had diabetes, 36% had dyslipidemia, 54% had depression, anxiety and insomnia, 40% had obesity. The stress score was higher in employees who developed diabetes, hypertension and depression. Early diagnosis of stress induced health problems can be made out by stress scores, intense lifestyle modification, diet advice along with psychological counselling would reduce the incidence of health problems in IT sector and improve the quality of work force. PMID:26015763
Health problems and stress in Information Technology and Business Process Outsourcing employees.
Padma, V; Anand, N N; Gurukul, S M G Swaminatha; Javid, S M A Syed Mohammed; Prasad, Arun; Arun, S
2015-04-01
Stress is high in software profession because of their nature of work, target, achievements, night shift, over work load. 1. To study the demographic profile of the employees. 2. To access the level of job stress and quality of life of the respondents. 3. To study in detail the health problems of the employees. All employees working in IT and BPO industry for more than two years were included into the study. A detailed questionnaire of around 1000 IT and BPO employees including their personal details, stress score by Holmes and Rahe to assess the level of stress and master health checkup profile were taken and the results were analysed. Around 56% had musculoskeletal symptoms. 22% had newly diagnosed hypertension,10% had diabetes, 36% had dyslipidemia, 54% had depression, anxiety and insomnia, 40% had obesity. The stress score was higher in employees who developed diabetes, hypertension and depression. Early diagnosis of stress induced health problems can be made out by stress scores, intense lifestyle modification, diet advice along with psychological counselling would reduce the incidence of health problems in IT sector and improve the quality of work force.
Gitchel, W. Dent; Roessler, Richard T.; Turner, Ronna C.
2011-01-01
Assessment is critical to rehabilitation practice and research, and self-reports are a commonly used form of assessment. This study examines a gender effect according to item wording on the "Perceived Stress Scale" for adults with multiple sclerosis. Past studies have demonstrated two-factor solutions on this scale and other scales measuring…
Bennett, J B; Lehman, W E
1998-09-01
While job-related alcohol use may be associated with problems for drinkers, less is known about the effects of employee drinking on co-workers. We hypothesized that either exposure to co-worker drinking or the presence of a drinking climate would positively correlate with reports of stress and other problems. Following previous research, we also predicted that work group cohesion (or team orientation) would buffer against such problems. Two random samples of municipal employees (Ns = 909 and 1,068) completed anonymous surveys. These assessed individual drinking, co-worker drinking, task-oriented group cohesion, the direct reports of negative consequences due to co-worker substance use, and five problem indicators: job stress, job withdrawal, health problems, and performance (work accidents and absences). In each sample, drinking climate correlated with stress and withdrawal more so than did reports of individual drinking. Drinking climate and individual job stress were negatively associated with cohesion. ANCOVA results indicated that drinking climate combined with low cohesion resulted in increased vulnerability for all five problems. Moreover, cohesion appeared to attenuate the negative impact of exposure to drinking norms. As many as 40% of employees report at least one negative consequence associated with co-worker substance use (alcohol and drugs). Because teamwork may buffer negative effects of drinking climate on co-workers, workplace prevention efforts might be enhanced through a focus on the social environment. These efforts would include team-building and discussions of the impact of co-worker drinking on employee productivity.
Application of nonlocal criteria for destruction in problems with a nonuniform stress field
Chevrychkina, A. A.; Gruzdkov, A. A.; Petrov, Yu. V.
2017-08-01
The dependence of the critical load on the degree of nonuniformity of the stress field is considered on the example of polymethylmethacrylate beams and plates with a round hole or a sharp notch. It is proposed to use nonlocal criteria for brittle fracture to describe the behavior of a nonuniformly stressed material. Among the criteria considered, the structural criterion is the most universal, because, in this case, the distance parameter d is least dependent on the test configuration. The distance parameters in problems with a regular concentrator are of the same order of magnitude, as in problems with a singular stress concentrator. A further modification of the criterion that takes into account the properties of the fracture process will probably make it possible to obtain a unique value for the length parameter for any degree of nonuniformity of the stress field.
Neece, C.; Baker, B.
2008-01-01
Background: Parents of children with intellectual disabilities (ID) typically report elevated levels of parenting stress, and child behaviour problems are a strong predictor of heightened parenting stress. Interestingly, few studies have examined child characteristics beyond behaviour problems that may also contribute to parenting stress. The…
Depression and work related stress problems, with notes of comparative law.
Amorosi, Marilisa; Pettinelli, Roberto
2013-09-01
This paper supplies both a medical and legal analysis of work related stress problems, by going throught the role of prevention in the European legal system. The Authors, after reviewing the negative role that stress has in the management of the employment relationship, describe the main steps that have brought Europe to recognize the importance of the role of prevention, and to recognize the role of well-being in the workplace.
Hybrid constraint programming and metaheuristic methods for large scale optimization problems
2011-01-01
This work presents hybrid Constraint Programming (CP) and metaheuristic methods for the solution of Large Scale Optimization Problems; it aims at integrating concepts and mechanisms from the metaheuristic methods to a CP-based tree search environment in order to exploit the advantages of both approaches. The modeling and solution of large scale combinatorial optimization problem is a topic which has arisen the interest of many researcherers in the Operations Research field; combinatori...
Child Behavior Problems, Teacher Executive Functions, and Teacher Stress in Head Start Classrooms.
Friedman-Krauss, Allison H; Raver, C Cybele; Neuspiel, Juliana M; Kinsel, John
2014-01-01
The current article explores the relationship between teachers' perceptions of child behavior problems and preschool teacher job stress, as well as the possibility that teachers' executive functions moderate this relationship. Data came from 69 preschool teachers in 31 early childhood classrooms in 4 Head Start centers and were collected using Web-based surveys and Web-based direct assessment tasks. Multilevel models revealed that higher levels of teachers' perceptions of child behavior problems were associated with higher levels of teacher job stress and that higher teacher executive function skills were related to lower job stress. However, findings did not yield evidence for teacher executive functions as a statistical moderator. Many early childhood teachers do not receive sufficient training for handling children's challenging behaviors. Child behavior problems increase a teacher's workload and consequently may contribute to feelings of stress. However, teachers' executive function abilities may enable them to use effective, cognitive-based behavior management and instructional strategies during interactions with students, which may reduce stress. Providing teachers with training on managing challenging behaviors and enhancing executive functions may reduce their stress and facilitate their use of effective classroom practices, which is important for children's school readiness skills and teachers' health.
Bos, Elisabeth H; Bouhuys, Antoinette L; Geerts, Erwin; van Os, Titus W D P; Ormel, Johan
2007-01-01
Interpersonal difficulties and stressful life events are important etiological factors in (recurrence of) depression. This study examines whether stressful life events mediate the influence of problems in nonverbal communication on recurrence of depression. We registered nonverbal expressions of involvement from videotaped behavior of 101 remitted outpatients and their interviewers. During a 2-year follow-up, we assessed stressful life events and recurrence of depression. The less congruent the levels of nonverbal involvement behavior of participants and interviewers, the higher the incidence of stressful life events, and -via these - the risk of recurrence. Nonverbal behavior was measured in an experimental setting. The results suggest that lack of nonverbal congruence during social interaction contributes to the occurrence of stressful life events, which in turn may trigger depression.
无
2000-01-01
The performance of analytical derivative and sparse matrix techniques applied to a traditional densesequential quadratic programming(SQP) is studied, and the strategy utilizing those techniques is also presented. Computational results on two typicalchemical optimization problems demonstrate significant enhancement in efficiency, which shows this strategy ispromising and suitable for large-scale process optimization problems.
Existence of Solutions for Nonlinear Four-Point -Laplacian Boundary Value Problems on Time Scales
Topal SGulsan
2009-01-01
Full Text Available We are concerned with proving the existence of positive solutions of a nonlinear second-order four-point boundary value problem with a -Laplacian operator on time scales. The proofs are based on the fixed point theorems concerning cones in a Banach space. Existence result for -Laplacian boundary value problem is also given by the monotone method.
Shen, Minxue; Hu, Ming; Sun, Zhenqiu
2017-01-01
Objectives To develop and validate brief scales to measure common emotional and behavioural problems among adolescents in the examination-oriented education system and collectivistic culture of China. Setting Middle schools in Hunan province. Participants 5442 middle school students aged 11–19 years were sampled. 4727 valid questionnaires were collected and used for validation of the scales. The final sample included 2408 boys and 2319 girls. Primary and secondary outcome measures The tools were assessed by the item response theory, classical test theory (reliability and construct validity) and differential item functioning. Results Four scales to measure anxiety, depression, study problem and sociality problem were established. Exploratory factor analysis showed that each scale had two solutions. Confirmatory factor analysis showed acceptable to good model fit for each scale. Internal consistency and test–retest reliability of all scales were above 0.7. Item response theory showed that all items had acceptable discrimination parameters and most items had appropriate difficulty parameters. 10 items demonstrated differential item functioning with respect to gender. Conclusions Four brief scales were developed and validated among adolescents in middle schools of China. The scales have good psychometric properties with minor differential item functioning. They can be used in middle school settings, and will help school officials to assess the students’ emotional/behavioural problems. PMID:28062469
Solving Large-Scale Inverse Magnetostatic Problems using the Adjoint Method
Bruckner, Florian; Wautischer, Gregor; Huber, Christian; Vogler, Christoph; Hinze, Michael; Suess, Dieter
2016-01-01
An efficient algorithm for the reconstruction of the magnetization state within magnetic components is presented. The occurring inverse magnetostatic problem is solved by means of an adjoint approach, based on the Fredkin-Koehler method for the solution of the forward problem. Due to the use of hybrid FEM-BEM coupling combined with matrix compression techniques the resulting algorithm is well suited for large-scale problems. Furthermore the reconstruction of the magnetization state within a permanent magnet is demonstrated.
Existence of Positive Solutions for Higher Order Boundary Value Problem on Time Scales
XIE DA-PENG; LIU YANG; SUN MING-ZHE; Li Yong
2013-01-01
In this paper,we investigate the existence of positive solutions of a class higher order boundary value problems on time scales.The class of boundary value problems educes a four-point (or three-point or two-point) boundary value problems,for which some similar results are established.Our approach relies on the Krasnosel'skii fixed point theorem.The result of this paper is new and extends previously known results.
Stress-constrained truss topology optimization problems that can be solved by linear programming
Stolpe, Mathias; Svanberg, Krister
2004-01-01
We consider the problem of simultaneously selecting the material and determining the area of each bar in a truss structure in such a way that the cost of the structure is minimized subject to stress constraints under a single load condition. We show that such problems can be solved by linear...... programming to give the global optimum, and that two different materials are always sufficient in an optimal structure....
Adaptation to Portuguese of the Depression, Anxiety and Stress Scales (DASS)
Apóstolo,João Luís Alves; Mendes,Aida Cruz; Azeredo,Zaida Aguiar
2006-01-01
Objective: to adapt to Portuguese, of Portugal, the Depression, Anxiety and Stress Scales, a 21-item short scale (DASS 21), designed to measure depression, anxiety and stress. Method: After translation and back-translation with the help of experts, the DASS 21 was administered to patients in external psychiatry consults (N=101), and its internal consistency, construct validity and concurrent validity were measured. Results: The DASS 21 properties certify its quality to measure emotional state...
Stress determination in thermally grown alumina scales using ruby luminescence
Renusch, D.; Veal, B.W.; Koshelev, I.; Natesan, K.; Grimsditch [Argonne National Lab., IL (United States); Hou, P.Y. [Lawrence Berkeley Lab., CA (United States)
1996-06-01
By exploiting the strain dependence of the ruby luminescence line, we have measured the strain in alumina scales thermally grown on Fe-Cr- Al alloys. Results are compared and found to be reasonably consistent with strains determined using x rays. Oxidation studies were carried out on alloys Fe - 5Cr - 28Al and Fe - 18Cr - 10Al (at.%). Significantly different levels of strain buildup were observed in scales on these alloys. Results on similar alloys containing a ``reactive element`` (Zr or Hf) in dilute quantity are also presented. Scales on alloys containing a reactive element (RE) can support significantly higher strains than scales on RE-free alloys. With the luminescence technique, strain relief associated with spallation thresholds is readily observed.
Review of the Psychometric Evidence of the Perceived Stress Scale
Eun-Hyun Lee, RN, PhD
2012-12-01
Conclusion: Overall, the PSS is an easy-to-use questionnaire with established acceptable psychometric properties. However, future studies should evaluate these psychometric properties in greater depth, and validate the scale using diverse populations.
Factor Structure of the Acute Stress Disorder Scale in a Sample of Hurricane Katrina Evacuees
Edmondson, Donald; Mills, Mary Alice; Park, Crystal L.
2010-01-01
Acute stress disorder (ASD) is a poorly understood and controversial diagnosis (A. G. Harvey & R. A. Bryant, 2002). The present study used confirmatory factor analysis (CFA) to test the factor structure of the most widely used self-report measure of ASD, the Acute Stress Disorder Scale (R. A. Bryant, M. L. Moulds, & R. M. Guthrie, 2000),…
Sun, Jiandong; Dunne, Michael P.; Hou, Xiang-yu; Xu, Ai-qiang
2011-01-01
This article describes the development and initial validation of a new instrument to measure academic stress--the Educational Stress Scale for Adolescents (ESSA). A series of cross-sectional questionnaire surveys were conducted with more than 2,000 Chinese adolescents to examine the psychometric properties. The final 16-item ESSA contains five…
Qin Ni
2001-01-01
An NGTN method was proposed for solving large-scale sparse nonlinear programming (NLP) problems. This is a hybrid method of a truncated Newton direction and a modified negative gradient direction, which is suitable for handling sparse data structure and possesses Q-quadratic convergence rate. The global convergence of this new method is proved,the convergence rate is further analysed, and the detailed implementation is discussed in this paper. Some numerical tests for solving truss optimization and large sparse problems are reported. The theoretical and numerical results show that the new method is efficient for solving large-scale sparse NLP problems.
MODIFIED BOTTLENECK-BASED PROCEDURE FOR LARGE-SCALE FLOW-SHOP SCHEDULING PROBLEMS WITH BOTTLENECK
ZUO Yan; GU Hanyu; XI Yugeng
2006-01-01
A new bottleneck-based heuristic for large-scale flow-shop scheduling problems with a bottleneck is proposed, which is simpler but more tailored than the shifting bottleneck (SB)procedure. In this algorithm, a schedule for the bottleneck machine is first constructed optimally and then the non-bottleneck machines are scheduled around the bottleneck schedule by some effective dispatching rules. Computational results show that the modified bottleneck-based procedure can achieve a tradeoff between solution quality and computational time comparing with SB procedure for medium-size problems. Furthermore it can obtain a good solution in quite short time for large-scale scheduling problems.
Confirmatory factor analysis of the Portuguese Depression Anxiety Stress Scales-21.
Apóstolo, João Luís Alves; Tanner, Barry Allen; Arfken, Cynthia Lee
2012-01-01
To determine which of three published models best characterizes the factor structure of the Portuguese version of the Depression Anxiety Stress Scales-21 and to assess its validity and reliability. Confirmatory factor analysis of Depression Anxiety and Stress Scale-21 for 1,297 adult, primary care outpatients (66.7% female, Mage = 48.57 years) comparing 3 models. The relationship between the Depression Anxiety Stress Scales-21 and the Positive and Negative Affect Schedule was analyzed. The correlated 3-factor model fit the data best. The scale demonstrated good internal consistency, with alpha scores of the subscales ranging from 0.836 to 0.897. Correlation with the Positive and Negative Affect Schedule was positive and moderate with the negative affect scale; it was negative and limited with the positive affect. These findings support the correlated 3-factor structure. The test demonstrated adequate reliability and construct validity, which supports its use for screening in primary care settings with Portuguese speakers.
Laurent, Heidemarie; Vergara-Lopez, Chrystal; Stroud, Laura R
2016-09-01
Efforts to define hypothalamic-pituitary-adrenal (HPA) axis profiles conferring risk for psychopathology have yielded inconclusive results, perhaps in part due to limited assessment of the stress response. In particular, research has typically focused on HPA responses to performance tasks, while neglecting the interpersonal stressors that become salient during adolescence. In this study we investigated links between psychosocial adjustment - youth internalizing and externalizing problems, as well as competence - and HPA responses to both performance and interpersonal stressors in a normative sample of children and adolescents. Participants (n = 59) completed a set of performance (public speaking, mental arithmetic, mirror tracing) and/or interpersonal (peer rejection) tasks and gave nine saliva samples, which were assayed for cortisol. Hierarchical linear models of cortisol response trajectories in relation to child behavior checklist (CBCL) scores revealed stressor- and sex-specific associations. Whereas internalizing problems related to earlier peaking, less dynamic cortisol responses to interpersonal stress (across males and females), externalizing problems related to lower, earlier peaking and less dynamic cortisol responses to performance stress for males only, and competence-related to later peaking cortisol responses to interpersonal stress for females only. Implications for understanding contextual stress profiles underlying different forms of psychopathology are discussed.
Verkleij, Marieke; van de Griendt, E-J.; Colland, V.; Van Loey, N.E.E.; Beelen, A.; Geenen, R.
2015-01-01
Our study examined parenting stress and its association with behavioral problems and disease severity in children with problematic severe asthma. Research participants were 93 children (mean age 13.4 ± 2.7 years) and their parents (86 mothers, 59 fathers). As compared to reference groups analyzed in
Reducing Teacher Stress by Implementing Collaborative Problem Solving in a School Setting
Schaubman, Averi; Stetson, Erica; Plog, Amy
2011-01-01
Student behavior affects teacher stress levels and the student-teacher relationship. In this pilot study, teachers were trained in Collaborative Problem Solving (CPS), a cognitive-behavioral model that explains challenging behavior as the result of underlying deficits in the areas of flexibility/adaptability, frustration tolerance, and problem…
Liles, Brandi D.; Newman, Elana; LaGasse, Linda L.; Derauf, Chris; Shah, Rizwan; Smith, Lynne M.; Arria, Amelia M.; Huestis, Marilyn A.; Haning, William; Strauss, Arthur; DellaGrotta, Sheri; Dansereau, Lynne M.; Neal, Charles; Lester, Barry M.
2012-01-01
The present study was designed to examine parenting stress, maternal depressive symptoms, and perceived child behavior problems among mothers who used methamphetamine (MA) during pregnancy. Participants were a subsample (n = 212; 75 exposed, 137 comparison) of biological mothers who had continuous custody of their child from birth to 36 months.…
Reducing Teacher Stress by Implementing Collaborative Problem Solving in a School Setting
Schaubman, Averi; Stetson, Erica; Plog, Amy
2011-01-01
Student behavior affects teacher stress levels and the student-teacher relationship. In this pilot study, teachers were trained in Collaborative Problem Solving (CPS), a cognitive-behavioral model that explains challenging behavior as the result of underlying deficits in the areas of flexibility/adaptability, frustration tolerance, and problem…
Temperament Moderates Associations between Exposure to Stress and Children's Externalizing Problems
Schermerhorn, Alice C.; Bates, John E.; Goodnight, Jackson A.; Lansford, Jennifer E.; Dodge, Kenneth A.; Pettit, Gregory S.
2013-01-01
The interaction between a temperament profile (four groups determined by high vs. low resistance to control [unmanageability] and unadaptability [novelty distress]) and family stress in predicting externalizing problems at school in children followed from kindergarten through eighth grade (ages 5-13) was investigated. The sample consisted of 556…
Size-scaling of tensile failure stress in boron carbide
Wereszczak, Andrew A [ORNL; Kirkland, Timothy Philip [ORNL; Strong, Kevin T [ORNL; Jadaan, Osama M. [University of Wisconsin, Platteville; Thompson, G. A. [U.S. Army Dental and Trauma Research Detachment, Greak Lakes
2010-01-01
Weibull strength-size-scaling in a rotary-ground, hot-pressed boron carbide is described when strength test coupons sampled effective areas from the very small (~ 0.001 square millimeters) to the very large (~ 40,000 square millimeters). Equibiaxial flexure and Hertzian testing were used for the strength testing. Characteristic strengths for several different specimen geometries are analyzed as a function of effective area. Characteristic strength was found to substantially increase with decreased effective area, and exhibited a bilinear relationship. Machining damage limited strength as measured with equibiaxial flexure testing for effective areas greater than ~ 1 mm2 and microstructural-scale flaws limited strength for effective areas less than 0.1 mm2 for the Hertzian testing. The selections of a ceramic strength to account for ballistically-induced tile deflection and to account for expanding cavity modeling are considered in context with the measured strength-size-scaling.
New Meta-Heuristic for Combinatorial Optimization Problems:Intersection Based Scaling
Peng Zou; Zhi Zhou; Ying-Yu Wan; Guo-Liang Chen; Jun Gu
2004-01-01
Combinatorial optimization problems are found in many application fields such as computer science, engineering and economy. In this paper, a new efficient meta-heuristic, Intersection-Based Scaling (IBS for abbreviation),is proposed and it can be applied to the combinatorial optimization problems. The main idea of IBS is to scale the size of the instance based on the intersection of some local optima, and to simplify the search space by extracting the intersection from the instance, which makes the search more efficient. The combination of IBS with some local search heuristics of different combinatorial optimization problems such as Traveling Salesman Problem (TSP) and Graph Partitioning Problem (GPP) is studied, and comparisons are made with some of the best heuristic algorithms and meta-heuristic algorithms. It is found that it has significantly improved the performance of existing local search heuristics and significantly outperforms the known best algorithms.
Benders' Decomposition Based Heuristics for Large-Scale Dynamic Quadratic Assignment Problems
Sirirat Muenvanichakul
2009-01-01
Full Text Available Problem statement: Dynamic Quadratic Assignment Problem (DQAP is NP hard problem. Benders decomposition based heuristics method is applied to the equivalent mixed-integer linear programming problem of the original DQAP. Approach: Approximate Benders Decomposition (ABD generates the ensemble of a subset of feasible layout for Approximate Dynamic Programming (ADP to determine the sub-optimal optimal solution. A Trust-Region Constraint (TRC for the master problem in ABD and a Successive Adaptation Procedure (SAP were implemented to accelerate the convergence rate of the method. Results: The sub-optimal solutions of large-scales DQAPs from the method and its variants were compared well with other metaheuristic methods. Conclusion: Overall performance of the method is comparable to other metaheuristic methods for large-scale DQAPs.
Methods and scales in soil erosion studies in Spain: problems and perspectives
Garcia-Ruiz, J. M.
2009-07-01
Soil erosion is a major problem in some areas of Spain. Research groups have studied a variety of aspects of this problem indifferent environments, and at a range of scales using a diversity of methods, from piquettes and rainfall simulation to experimental plots, catchment and large regional areas. This has increased knowledge and identified the main problems: farmland abandonment, badlands erosion, the effects of land use changes, and the role of extreme events and erosion in certain crops (particularly vineyards). However, comparison of results among various research groups has been difficult, posing problems in developing solutions from State and Regional administrators. (Author) 73 refs.
Direct visualization of particle scale internal stresses in a colloidal glass
Cohen, Itai; Lin, Neil; Bierbaum, Matt; Sethna, James
2015-11-01
Bullet proof windshields, smart phone screens, and Prince Rupert's drop are all examples of how internal stresses can dramatically affect the strength of glass. Imaging the way internal stresses are distributed and their evolution under an applied load remains prohibitively difficult. For example, work on disordered granular packs suggests that stress heterogeneity may extend down to the scale of a single particle. While resolving stresses at the single atom scale is not feasible, measurements of stresses at the single particle scale in colloidal glasses, a widely used model system for atomic glasses, can be achieved by using Stress Assessment from Local Structural Anisotropy (SALSA). This method relies solely on the particle configurations obtained via high speed confocal microscopy. Here, we use SALSA to visualize the three dimensional stress network in a colloidal glass. By placing the suspension under shear we determine the evolution of this network and how it alters the bulk mechanical behavior of the suspension. Our work constitutes a first step towards understanding how local variations in the stress networks of glasses can lead to the dramatic mechanical properties of tempered glass.
Effect and mechanism of stresses on rock permeability at different scales
YIN; Shangxian; WANG; Shangxu
2006-01-01
The effect of geo-stress fields on macroscopic hydro-geological conditions or microcosmic permeability of water-bearing media should follow some laws or principles. Cases study and tests show that: (1) At macro-geologic large scale, deformed and crashed rocks which were induced by geo-stress fields changing provided space for groundwater storage and flow. Groundwater adjusts water-bearing space and dilatants fractures by flowing and press transferring. Coupling of liquid and solid can be implemented for rocks and groundwater. Although tectonic fields witness several times of change and build-up in geological time, stress fields forming regional tectonic framework are coherent with seepage fields, orientation of the maximum horizontal stress demonstrates main seepage directions. (2) At macro-geologic middle scale, zones of stresses changing sharply, quite low stresses,stress or shear concentration can be used to show locations and types of main fractures, zones of geo-stresses changing equably can be acted as normal base media zones of tri-porosity media. (3) At micro-geologic small scale, tri-porosity media include fractured rocks, porous rocks and capillary rocks. Investigations indicate that porosity or permeability is functions of effective stresses, and porosity or permeability changing rules of porous rocks with variation of effective stresses can be described as the index model, the model of power exponent functions is suitable for those of fractured rocks, the model of the second power parabola for capillary rocks. The porosity and permeability loss in fractured rocks, which are greater than that in porous rocks, are shown by calculation of effective compressive coefficient and closing pressure in cracks. The calculations can also explain themechanism why porosity changes are always larger than permeability changes. It is proved by the thick wall cylinder theory that the second power parabola relation between porosity or permeability loss and effective
Solving Large Scale Nonlinear Eigenvalue Problem in Next-Generation Accelerator Design
Liao, Ben-Shan; Bai, Zhaojun; /UC, Davis; Lee, Lie-Quan; Ko, Kwok; /SLAC
2006-09-28
A number of numerical methods, including inverse iteration, method of successive linear problem and nonlinear Arnoldi algorithm, are studied in this paper to solve a large scale nonlinear eigenvalue problem arising from finite element analysis of resonant frequencies and external Q{sub e} values of a waveguide loaded cavity in the next-generation accelerator design. They present a nonlinear Rayleigh-Ritz iterative projection algorithm, NRRIT in short and demonstrate that it is the most promising approach for a model scale cavity design. The NRRIT algorithm is an extension of the nonlinear Arnoldi algorithm due to Voss. Computational challenges of solving such a nonlinear eigenvalue problem for a full scale cavity design are outlined.
Stress cardiomyopathy: Is it limited to Takotsubo syndrome? Problems of definition.
Sarapultsev, Petr A; Sarapultsev, Alexey P
2016-10-15
In 2006, Takotsubo syndrome (TTC) was described as a distinct type of stress-induced cardiomyopathy (stress cardiomyopathy). However, when thinking about Takotsubo cardiomyopathy from the viewpoints of the AHA and ESC classifications, 2 possible problems may arise. The first potential problem is that a forecast of disease outcome is lacking in the ESC classification, whereas the AHA only states that 'outcome is favorable with appropriate medical therapy'. However, based on the literature data, one can make a general conclusion that occurrence of myocardial lesions in TTC (i.e., myocardial fibrosis and contraction-band necrosis) causes the same effects as in other diseases with similar levels of myocardial damage and should not be considered to have a lesser impact on mortality. To summarise, TTC can cause not only severe complications such as pulmonary oedema, cardiogenic shock, and dangerous ventricular arrhythmias, but also damage to the myocardium, which can result in the development of potentially fatal conditions even after the disappearance of LV apical ballooning. The second potential problem arises from the definition of TTC as a stress cardiomyopathy in the AHA classification. In fact, the main factors leading to TTC are stress and microvascular anginas, since, as has been already discussed, coronary spasm can cause myocardium stunning, resulting in persistent apical ballooning. Thus, based on this review, 3 distinct types of stress cardiomyopathies exist (variant angina, microvascular angina, and TTC), with poor prognosis. Adding these diseases to the classification of cardiomyopathies will facilitate diagnosis and preventive prolonged treatment, which should include intensive anti-stress therapy. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.
Molaro, Jamie L; Langer, Steve A
2015-01-01
Thermomechanical processes such as fatigue and shock have been suggested to cause and contribute to rock breakdown on Earth, and on other planetary bodies, particularly airless bodies in the inner solar system. In this study, we modeled grain-scale stresses induced by diurnal temperature variations on simple microstructures made of pyroxene and plagioclase on various solar system bodies. We found that a heterogeneous microstructure on the Moon experiences peak tensile stresses on the order of 100 MPa. The stresses induced are controlled by the coefficient of thermal expansion and Young's modulus of the mineral constituents, and the average stress within the microstructure is determined by relative volume of each mineral. Amplification of stresses occurs at surface-parallel boundaries between adjacent mineral grains and at the tips of pore spaces. We also found that microscopic spatial and temporal surface temperature gradients do not correlate with high stresses, making them inappropriate proxies for investig...
Combining Nearest Neighbor Search with Tabu Search for Large-Scale Vehicle Routing Problem
Du, Lingling; He, Ruhan
The vehicle routing problem is a classical problem in operations research, where the objective is to design least cost routes for a fleet of identical capacitated vehicles to service geographically scattered customers. In this paper, we present a new and effective hybrid metaheuristic algorithm for large-scale vehicle routing problem. The algorithm combines the strengths of the well-known Nearest Neighbor Search and Tabu Search into a two-stage procedure. More precisely, Nearest Neighbor Search is used to construct initial routes in the first stage and the Tabu Search is utilized to optimize the intra-route and the inter-route in the second stage. The presented algorithm is specifically designed for large-scale problems. The computational experiments were carried out on a standard benchmark and a real dataset with 6772 tobacco customers. The results demonstrate that the suggested method is highly competitive.
Arancibia-Martini, Héctor; Ruiz, Miguel Á; Blanco, Amalio; Cárdenas, Manuel
2016-04-01
Given the current debate over the distinction between subtle and blatant prejudice, this study provides new evidence regarding problems with the construct validity of the Pettigrew and Meertens' Blatant and Subtle Prejudice Scale. To assess these issues, an existing data sample of 896 Chilean participants collected in 2010 was reanalyzed. The main analysis method used was a confirmatory factor analysis. The model that best represented the original theory (a model of two correlated second-order factors) had an improper solution due to the unidentified model. The scale has substantial psychometric problems, and it was not possible to distinguish between subtle and blatant prejudice.
Small Scale Problems of the ΛCDM Model: A Short Review
Antonino Del Popolo
2017-02-01
Full Text Available The ΛCDM model, or concordance cosmology, as it is often called, is a paradigm at its maturity. It is clearly able to describe the universe at large scale, even if some issues remain open, such as the cosmological constant problem, the small-scale problems in galaxy formation, or the unexplained anomalies in the CMB. ΛCDM clearly shows difficulty at small scales, which could be related to our scant understanding, from the nature of dark matter to that of gravity; or to the role of baryon physics, which is not well understood and implemented in simulation codes or in semi-analytic models. At this stage, it is of fundamental importance to understand whether the problems encountered by the ΛDCM model are a sign of its limits or a sign of our failures in getting the finer details right. In the present paper, we will review the small-scale problems of the ΛCDM model, and we will discuss the proposed solutions and to what extent they are able to give us a theory accurately describing the phenomena in the complete range of scale of the observed universe.
On unified modeling, theory, and method for solving multi-scale global optimization problems
Gao, David Yang
2016-10-01
A unified model is proposed for general optimization problems in multi-scale complex systems. Based on this model and necessary assumptions in physics, the canonical duality theory is presented in a precise way to include traditional duality theories and popular methods as special applications. Two conjectures on NP-hardness are proposed, which should play important roles for correctly understanding and efficiently solving challenging real-world problems. Applications are illustrated for both nonconvex continuous optimization and mixed integer nonlinear programming.
Ergul, Ozgur
2014-01-01
The Multilevel Fast Multipole Algorithm (MLFMA) for Solving Large-Scale Computational Electromagnetic Problems provides a detailed and instructional overview of implementing MLFMA. The book: Presents a comprehensive treatment of the MLFMA algorithm, including basic linear algebra concepts, recent developments on the parallel computation, and a number of application examplesCovers solutions of electromagnetic problems involving dielectric objects and perfectly-conducting objectsDiscusses applications including scattering from airborne targets, scattering from red
A NESTED PARTITIONS FRAMEWORK FOR SOLVING LARGE-SCALE MULTICOMMODITY FACILITY LOCATION PROBLEMS
Leyuan SHI; Robert R.MEYER; Mehmet BOZBAY; Andrew J.MILLER
2004-01-01
Large-scale multicommodity facility location problems are generally intractable with respect to standard mixed-integer programming (MIP) tools such as the direct application of general-purpose Branch & Cut (BC) commercial solvers i.e. CPLEX. In this paper, the authors investigate a nested partitions (NP) framework that combines meta-heuristics with MIP tools (including branch-and-cut).We also consider a variety of alternative formulations and decomposition methods for this problem class. Our results show that our NP framework is capable of efficiently producing very high quality solutions to multicommodity facility location problems. For large-scale problems in this class, this approach is significantly faster and generates better feasible solutions than either CPLEX (applied directly to the given MIP) or the iterative Lagrangian-based methods that have generally been regarded as the most effective structure-based techniques for optimization of these problems. We also briefly discuss some other large-scale MIP problem classes for which this approach is expected to be very effective.
Curtin, C.; Hubbard, K.; Anderson, S. E.; Mick, E.; Must, A.; Bandini, L. G.
2015-01-01
Mealtime behavior problems and family stress occur frequently among families of children with autism spectrum disorder (ASD). However, it is unknown whether food selectivity is an associated factor. The associations of high food selectivity with mealtime behavior problems, spousal stress, and influence on family members were assessed among 53…
Curtin, C.; Hubbard, K.; Anderson, S. E.; Mick, E.; Must, A.; Bandini, L. G.
2015-01-01
Mealtime behavior problems and family stress occur frequently among families of children with autism spectrum disorder (ASD). However, it is unknown whether food selectivity is an associated factor. The associations of high food selectivity with mealtime behavior problems, spousal stress, and influence on family members were assessed among 53…
Chung, Kyong-Mee; Ebesutani, Chad; Bang, Hye Min; Kim, Joohee; Chorpita, Bruce F.; Weisz, John R.; Suh, Dongsoo; Byun, Heejung
2013-01-01
Due to increased multiculturalism in the US and abroad, there is a need for increased understanding of the different ways in which parenting stress is related to child problems across cultures. In the present study, we investigated (a) differences in reported parenting stress and childhood problem behaviors across a Korean (n = 71) and US (n = 71)…
Kwon, Jeong Yoon
2007-01-01
The current study examined the relationship between Korean mothers' parenting stress and parental intelligence, and child behavior problems as well as the mediation effects of parental intelligence, which tested the association between parenting stress and child behavior problems. A sample of 436 typically developing children and their mothers…
Barbosa-Leiker, Celestina; Kostick, Marylynne; Lei, Ming; McPherson, Sterling; Roper, Virginia; Hoekstra, Trynke; Wright, Bruce
2013-08-01
Measurement invariance of the 2-factor model of the Perceived Stress Scale--10-item version (Cohen & Williamson, 1988) was tested across men and women at two time points and in the combined total sample over a 2-year time frame (n = 871). Measurement invariance results indicated that the scale measured the latent factors, stress and counter-stress, equivalently in men and women and over time. With measurement invariance demonstrated, differences in latent means were tested. Results indicated that men had lower levels of frequencies of stressors, and at one time point, higher levels of counter-stress, when compared with women. When examining change in frequencies of stressors and counter-stress over 2 years with the combined male and female sample, stressors remained stable, yet counter-stress increased over time. These findings may aid in the interpretation of results when examining stressors and counter-stress in clinical samples where one would expect stress to increase, whereas positive psychological states decrease.
Huang, Zhi; Liu, Xiangnan; Jin, Ming; Ding, Chao; Jiang, Jiale; Wu, Ling
2016-03-07
Accurate monitoring of heavy metal stress in crops is of great importance to assure agricultural productivity and food security, and remote sensing is an effective tool to address this problem. However, given that Earth observation instruments provide data at multiple scales, the choice of scale for use in such monitoring is challenging. This study focused on identifying the characteristic scale for effectively monitoring heavy metal stress in rice using the dry weight of roots (WRT) as the representative characteristic, which was obtained by assimilation of GF-1 data with the World Food Studies (WOFOST) model. We explored and quantified the effect of the important state variable LAI (leaf area index) at various spatial scales on the simulated rice WRT to find the critical scale for heavy metal stress monitoring using the statistical characteristics. Furthermore, a ratio analysis based on the varied heavy metal stress levels was conducted to identify the characteristic scale. Results indicated that the critical threshold for investigating the rice WRT in monitoring studies of heavy metal stress was larger than 64 m but smaller than 256 m. This finding represents a useful guideline for choosing the most appropriate imagery.
Solving a large-scale precedence constrained scheduling problem with elastic jobs using tabu search
Pedersen, C.R.; Rasmussen, R.V.; Andersen, Kim Allan
2007-01-01
This paper presents a solution method for minimizing makespan of a practical large-scale scheduling problem with elastic jobs. The jobs are processed on three servers and restricted by precedence constraints, time windows and capacity limitations. We derive a new method for approximating the server...... exploitation of the elastic jobs and solve the problem using a tabu search procedure. Finding an initial feasible solution is in general -complete, but the tabu search procedure includes a specialized heuristic for solving this problem. The solution method has proven to be very efficient and leads...
Solving Large-Scale Inverse Magnetostatic Problems using the Adjoint Method
Bruckner, Florian; Abert, Claas; Wautischer, Gregor; Huber, Christian; Vogler, Christoph; Hinze, Michael; Suess, Dieter
2017-01-01
An efficient algorithm for the reconstruction of the magnetization state within magnetic components is presented. The occurring inverse magnetostatic problem is solved by means of an adjoint approach, based on the Fredkin-Koehler method for the solution of the forward problem. Due to the use of hybrid FEM-BEM coupling combined with matrix compression techniques the resulting algorithm is well suited for large-scale problems. Furthermore the reconstruction of the magnetization state within a permanent magnet as well as an optimal design application are demonstrated.
Solving Large-Scale Inverse Magnetostatic Problems using the Adjoint Method
Bruckner, Florian; Abert, Claas; Wautischer, Gregor; Huber, Christian; Vogler, Christoph; Hinze, Michael; Suess, Dieter
2017-01-01
An efficient algorithm for the reconstruction of the magnetization state within magnetic components is presented. The occurring inverse magnetostatic problem is solved by means of an adjoint approach, based on the Fredkin-Koehler method for the solution of the forward problem. Due to the use of hybrid FEM-BEM coupling combined with matrix compression techniques the resulting algorithm is well suited for large-scale problems. Furthermore the reconstruction of the magnetization state within a permanent magnet as well as an optimal design application are demonstrated. PMID:28098851
Minimization of Linear Functionals Defined on| Solutions of Large-Scale Discrete Ill-Posed Problems
Elden, Lars; Hansen, Per Christian; Rojas, Marielba
2003-01-01
The minimization of linear functionals de ned on the solutions of discrete ill-posed problems arises, e.g., in the computation of con dence intervals for these solutions. In 1990, Elden proposed an algorithm for this minimization problem based on a parametric-programming reformulation involving...... the solution of a sequence of trust-region problems, and using matrix factorizations. In this paper, we describe MLFIP, a large-scale version of this algorithm where a limited-memory trust-region solver is used on the subproblems. We illustrate the use of our algorithm in connection with an inverse heat...
Investigation of independent verification and validation of the servicemen occupational stress scale
Jia XU
2012-12-01
Full Text Available Objective To examine the reliability and validity of the servicemen occupational stress scale. Methods A survey with the servicemen occupational stress scale was carried out on 1100 randomly chosen military personnel in the army, and 106 among them also underwent examination with Chinese Military Mental Health Scale (CMMHS at the same time. Results The Cronbach's α coefficient of total scale was 0.929, and subscales were 0.731-0.857 (P<0.01; the half reliability of total scale was 0.932, and subscales were 0.465-0.881 (P<0.01. The correlation coefficients among factors and between factors and total scale score were 0.699-0.900 (P<0.01. The factors of the servicemen occupational stress scale showed a significant correlation with most factors of the CMMHS, the correlation coefficients were 0.186-0253. According to the results of exploratory factor analysis, it was showed that the scale of the entries in the collation and factors named were more reasonable. According to the results of confirmatory factor analysis, there was a higher degree of accordance between the sample data and the hypothesized structure of factors, with Chi-Square statistic equal to 8293.0, RMSEA (root mean square error of approximation equal to 0.055, RMR (root mean square residual equal to 0.031, TLI (Tucker-Lewis index, CFI (comparative fit index, IFI (incremental fit index and GFI (goodness of fit index 0.919, 0.926, 0.920, 0.915, respectively. Conclusion The reliability and validity of the servicemen occupational stress scale meet the standards for scale designing.
Jamshidian, M., E-mail: mostafa.jamshidian@gmail.com [Department of Mechanical Engineering, Isfahan University of Technology, Isfahan (Iran, Islamic Republic of); Institute of Structural Mechanics, Bauhaus-University Weimar, Marienstrasse 15, 99423 Weimar (Germany); Rabczuk, T., E-mail: timon.rabczuk@uni-weimar.de [Institute of Structural Mechanics, Bauhaus-University Weimar, Marienstrasse 15, 99423 Weimar (Germany); School of Civil, Environmental and Architectural Engineering, Korea University, Seoul (Korea, Republic of)
2014-03-15
We establish the correlation between the diffuse interface and sharp interface descriptions for stressed grain boundary migration by presenting analytical solutions for stressed migration of a circular grain boundary in a bicrystalline phase field domain. The validity and accuracy of the phase field model is investigated by comparing the phase field simulation results against analytical solutions. The phase field model can reproduce precise boundary kinetics and stress evolution provided that a thermodynamically consistent theory and proper expressions for model parameters in terms of physical material properties are employed. Quantitative phase field simulations are then employed to investigate the effect of microstructural length scale on microstructure and texture evolution by stressed grain growth in an elastically deformed polycrystalline aggregate. The simulation results reveal a transitional behaviour from normal to abnormal grain growth by increasing the microstructural length scale.
TRANSIENT THERMAL STRESSES IN AN ORTHOTROPIC HOLLOW CYLINDER FOR AXISYMMETRIC PROBLEMS
DING Haojiang; WANG Huiming; CHEN Weiqiu
2004-01-01
For the thermoelastic dynamic axisymmetric problem of a finite orthotropic hollow cylinder, one comes closer to reality to involve the effect of axial strain than to consider the plane strain case only. However, additional mathematical difficulties should be encountered and a different solution procedure should be developed. By the separation of variables, the thermoelastic axisymmetric dynamic problem of an orthotropic hollow cylinder taking account of the axial strain is transformed to a Volterra integral equation of the second kind for a function of time, which can be solved efficiently and quickly by the interpolation method. The solutions of displacements and stresses are obtained.It is noted that the present method is suitable for an orthotropic hollow cylinder with an arbitrary thickness subjected to arbitrary axisymmetric thermal loads. Numerical comparison is made to show the effect of the axial strain on the displacements and stresses.
An adaptation of the Interpersonal Problem Areas Rating Scale: pilot and interrater agreement study
de Andrade, Ana Claudia Fontes; Frank, Ellen; Neto, Francisco Lotufo; Houck, Patricia R
2012-01-01
Objective This article describes the adaptation of a rating scale of interpersonal psychotherapy problem areas to include a fifth problem area appropriate to bipolar disorder and an interrater agreement study in identifying interpersonal problem areas and selecting a primary treatment focus if patients were to engage in treatment. Method Five research interpersonal psychotherapists assessed nine audiotapes of a single interview with five bipolar and four unipolar patients in which the interpersonal inventory and identification of problem areas were undertaken. Results Raters agreed on presence and absence of problem areas in seven tapes. Kappas for identification of problem areas were 1.00 (grief), 0.77 (role dispute), 0.61 (role transition), 0.57 (interpersonal deficits) and 1.00 (loss of healthy self). Kappa for agreement on a primary clinical focus if patients were to engage in interpersonal psychotherapy treatment was 0.64. Conclusions The adaptation of the original scale to include an area pertinent to bipolar disorder proved to be applicable and relevant for use with this population. The results show substantial interrater agreement in identifying problem areas and potential treatment focus. PMID:19142412
An Integer Programming-based Local Search for Large-scale Maximal Covering Problems
Junha Hwang
2011-02-01
Full Text Available Maximal covering problem (MCP is classified as a linear integer optimization problem which can be effectively solved by integer programming technique. However, as the problem size grows, integerprogramming requires excessive time to get an optimal solution. This paper suggests a method for applying integer programming-based local search (IPbLS to solve large-scale maximal covering problems. IPbLS, which is a hybrid technique combining integer programming and local search, is a kind of local search using integer programming for neighbor generation. IPbLS itself is very effective for MCP. In addition, we improve the performance of IPbLS for MCP through problem reduction based on the current solution. Experimental results show that the proposed method considerably outperforms any other local search techniques and integer programming.
Cheng, Hsiu-Lan; Mallinckrodt, Brent
2015-01-01
Racial/ethnic discrimination has been identified as a risk factor in the development of posttraumatic stress disorder (PTSD) symptoms in persons of color (Carter, 2007). Many persons, regardless of race/ethnicity, with PTSD symptoms resulting from combat, violent crimes, sexual assault, or natural disasters use alcohol in an attempt to cope. This longitudinal study surveyed 203 Hispanic/Latino students twice at approximately a 1-year interval, and used a cross-lagged design to compare Time 1 links from alcohol use and experiences of discrimination with the same variables at Time 2, plus symptoms of PTSD. Each survey included the General Ethnic Discrimination scale and the Alcohol Use Disorders Identification Test. Only Time 2 packets contained the Posttraumatic Stress Disorder Checklist-Civilian. Cross-lagged analyses conducted by comparing nested structural equation models found that fixing the causal paths to zero from Time 1 experiences of discrimination to Time 2 alcohol problems and PTSD resulted in a significantly worse fit of the data. However, fixing the paths to zero from Time 1 maladaptive alcohol use to Time 2 PTSD and experiences of discrimination resulted in no significant difference in model fit. Thus, this pattern of findings is consistent with an inference that Hispanic/Latino college students who experience racial/ethnic discrimination are at risk for developing symptoms of posttraumatic stress and increased maladaptive alcohol use; conversely, maladaptive alcohol use does not appear to be a risk factor for later experiences of discrimination or PTSD symptoms.
Field-based observations confirm linear scaling of sand flux with wind stress
Martin, Raleigh L
2016-01-01
Wind-driven sand transport generates atmospheric dust, forms dunes, and sculpts landscapes. However, it remains unclear how the sand flux scales with wind speed, largely because models do not agree on how particle speed changes with wind shear velocity. Here, we present comprehensive measurements from three new field sites and three published studies, showing that characteristic saltation layer heights, and thus particle speeds, remain approximately constant with shear velocity. This result implies a linear dependence of saltation flux on wind shear stress, which contrasts with the nonlinear 3/2 scaling used in most aeolian process predictions. We confirm the linear flux law with direct measurements of the stress-flux relationship occurring at each site. Models for dust generation, dune migration, and other processes driven by wind-blown sand on Earth, Mars, and several other planetary surfaces should be modified to account for linear stress-flux scaling.
Effects of displacement boundary conditions on thermal deformation in thermal stress problems
S. Y. Kwak
2013-05-01
Full Text Available Most computational structural engineers are paying more attention to applying loads rather than to DBCs (Displacement Boundary Conditions because most static stable mechanical structures are working under already prescribed displacement boundary conditions. In all of the computational analysis of solving a system of algebraic equations, such as FEM (Finite Element Method, three translational and three rotational degrees of freedom (DOF should be constrained (by applying DBCs before solving the system of algebraic equation in order to prevent rigid body motions of the analysis results (singular problem. However, it is very difficult for an inexperienced engineer or designer to apply proper DBCs in the case of thermal stress analysis where no prescribed DBCs or constraints exist, for example in water quenching for heat treatment. Moreover, improper DBCs cause incorrect solutions in thermal stress analysis, such as stress concentration or unreasonable deformation phases. To avoid these problems, we studied a technique which performs the thermal stress analysis without any DBCs; and then removes rigid body motions from the deformation results in a post process step as the need arises. The proposed technique makes it easy to apply DBCs and prevent the error caused by improper DBCs. We proved it was mathematically possible to solve a system of algebraic equations without a step of applying DBCs. We also compared the analysis results with those of a traditional procedure for real castings.
Controlling Barium Sulphate Scale Deposition Problems in an unbleached Kraft Paper Mill
Sithole, Bruce
2015-06-01
Full Text Available /phosphonates and polyacrylates were effective in reducing and controlling the scale deposit problems. Institution of these measures led to a cleaner paper machine that required far fewer boil outs than before. In addition, productivity improved and the fisheye defects...
A note on solving large-scale zero-one programming problems
Adema, Jos J.
1988-01-01
A heuristic for solving large-scale zero-one programming problems is provided. The heuristic is based on the modifications made by H. Crowder et al. (1983) to the standard branch-and-bound strategy. First, the initialization is modified. The modification is only useful if the objective function valu
Large scale inverse problems computational methods and applications in the earth sciences
Scheichl, Robert; Freitag, Melina A; Kindermann, Stefan
2013-01-01
This book is thesecond volume of three volume series recording the ""Radon Special Semester 2011 on Multiscale Simulation & Analysis in Energy and the Environment"" taking place in Linz, Austria, October 3-7, 2011. The volume addresses the common ground in the mathematical and computational procedures required for large-scale inverse problems and data assimilation in forefront applications.
A Minimum-Cost Network-Flow Solution to the Case v Thurstone Scaling Problem.
Lattin, James M.
1990-01-01
An approach is presented for determining unidimensional scale estimates that are relatively insensitive to limited inconsistencies in paired comparisons data. The solution procedure--a minimum-cost network-flow problem--is presented in conjunction with a sensitivity diagnostic that assesses the influence of a single pairwise comparison on…
A note on solving large-scale zero-one programming problems
Adema, Jos J.
1988-01-01
A heuristic for solving large-scale zero-one programming problems is provided. The heuristic is based on the modifications made by H. Crowder et al. (1983) to the standard branch-and-bound strategy. First, the initialization is modified. The modification is only useful if the objective function valu
A note on solving large-scale zero-one programming problems
Adema, Jos J.
1988-01-01
A heuristic for solving large-scale zero-one programming problems is provided. The heuristic is based on the modifications made by H. Crowder et al. (1983) to the standard branch-and-bound strategy. First, the initialization is modified. The modification is only useful if the objective function
Yepeng Xing; Qiong Wang; Valery G. Romanovski
2009-01-01
We prove several new comparison results and develop the monotone iterative tech-nique to show the existence of extremal solutions to a kind of periodic boundary value problem (PBVP) for nonlinear integro-differential equation of mixed type on time scales.
Gauthier-Duchesne, Amélie; Hébert, Martine; Daspe, Marie-Ève
2017-02-01
Despite the proliferation of studies documenting outcomes in sexually abused victims, gender differences remain understudied. The bulk of studies have relied on retrospective samples of adults with insufficient representation of male victims to explore gender specificities. This study examined differential outcomes among boy and girl victims of sexual abuse. A predictive model of outcomes including abuse characteristics and sense of guilt as mediators was proposed. Path analysis was conducted with a sample of 447 sexually abused children (319 girls and 128 boys), aged 6-12. Being a girl was a predictor of posttraumatic stress symptoms, while being a boy was a predictor of externalizing problems. Being a boy was also associated with more severe abuse, which in turn predicted posttraumatic stress symptoms. Child's gender was not related to perpetrator's relationship to the child or sense of guilt. However, sense of guilt predicted posttraumatic stress symptoms and externalizing problems while perpetrator's relationship to the child predicted externalizing problems. Gender specificities should be further studied among sexually abused children, as boys and girls appear to manifest different outcomes. Sense of guilt should be a target in intervention for sexually abused children, as results highlight its link to heightened negative outcomes.
Overhanging Features and the SLM/DMLS Residual Stresses Problem: Review and Future Research Need
Albert E. Patterson
2017-04-01
Full Text Available A useful and increasingly common additive manufacturing (AM process is the selective laser melting (SLM or direct metal laser sintering (DMLS process. SLM/DMLS can produce full-density metal parts from difficult materials, but it tends to suffer from severe residual stresses introduced during processing. This limits the usefulness and applicability of the process, particularly in the fabrication of parts with delicate overhanging and protruding features. The purpose of this study was to examine the current insight and progress made toward understanding and eliminating the problem in overhanging and protruding structures. To accomplish this, a survey of the literature was undertaken, focusing on process modeling (general, heat transfer, stress and distortion and material models, direct process control (input and environmental control, hardware-in-the-loop monitoring, parameter optimization and post-processing, experiment development (methods for evaluation, optical and mechanical process monitoring, imaging and design-of-experiments, support structure optimization and overhang feature design; approximately 143 published works were examined. The major findings of this study were that a small minority of the literature on SLM/DMLS deals explicitly with the overhanging stress problem, but some fundamental work has been done on the problem. Implications, needs and potential future research directions are discussed in-depth in light of the present review.
Schleider, Jessica L; Patel, Anushka; Krumholz, Lauren; Chorpita, Bruce F; Weisz, John R
2015-02-01
This study tested whether family income and stress in the parent-youth relationship might mediate links between parent symptoms and youth problems, and whether the process might differ for youth externalizing versus internalizing problems. We used a multiple mediation technique to test pathways by which family income and stress in the parent-child relationship might relate to parent-youth symptom associations in a sample of clinically-referred 7-13 year-olds (32% female; M age = 10.16 years). Family income and stress jointly mediated the relation between parent symptoms and youth externalizing problems but not between parent symptoms and youth internalizing problems. Future longitudinal research should investigate whether low income and parent-youth stress may deplete the parental resources needed to manage youth externalizing behavior. This study extends existing literature by suggesting a specific pattern by which two identified risk factors for youth problems may operate jointly, and by showing specificity to externalizing problems.
Stress and adhesion of chromia-rich scales on ferritic stainless steels in relation with spallation
A. Galerie
2004-03-01
Full Text Available The relation between chromia scale spallation during oxidation or cooling down of ferritic stainless steels is generally discussed in terms of mechanical stresses induced by volume changes or differential thermal expansion. In the present paper, growth and thermal stress measurements in scales grown on different ferritic steel grades have shown that the main stress accumulation occurs during isothermal scale growth and that thermal stresses are of minor importance. However, when spallation occurs, it is always during cooling down. Steel-oxide interface undulation seems to play a major role at this stage, thus relating spallation to the metal mechanical properties, thickness and surface preparation. A major influence on spallation of the minor stabilizing elements of the steels was observed which could not be related to any difference in stress state. Therefore, an original inverted blister test was developed to derive quantitative values of the metal-oxide adhesion energy. These values clearly confirmed that this parameter was influenced by scale thickness and by minor additions, titanium greatly increasing adhesion whereas niobium decreased it.
Stress drop Scaling and Stress Release in the Darfield-Christchurch, New Zealand Earthquake Sequence
Abercrombie, R. E.; Fry, B.; Gerstenberger, M. C.; Doser, D. I.; Bannister, S. C.
2012-12-01
To investigate earthquake rupture dynamics, and which factors (e.g. normal stress, strain rate, fluids, rheology) govern the earthquake source and consequent ground motions, we need to study earthquakes over a wide range of magnitudes, from a diverse range of tectonic environments. The uncertainties and discrepancies between studies of earthquake stress drop are a frustration to all those who are interested in earthquake source and fault dynamics. There is controversy over whether the earthquake rupture process is self-similar and whether it varies with tectonic setting; different studies give different results. It is unclear whether this is due to differences between the earthquakes, or the analysis methods. We are developing a direct wave, spectral ratio analysis approach that includes realistic estimates of uncertainties and has strict objective criteria for assessing the quality of an EGF derived spectral ratio (Abercrombie, 2012, submitted). Comparing this approach to other methods reveals significant random and systematic biases, enabling us to improve our understanding of the real uncertainties. The Canterbury earthquake sequence that began with the M7.1 Darfield earthquake in September 2010, and includes the devastating M6.2 Christchurch earthquake in February 2011 is a very active sequence within a low strain rate tectonic setting. To date there have been 15 earthquakes with M>5.5. High quality recording and accurate relocations make this an ideal sequence to investigate any spatial, temporal, or magnitude dependence to stress drop. The largest earthquakes appear to have relatively high stress drops (and apparent stress), consistent with the high ground accelerations and damage in Christchurch. This observation is also consistent with the hypothesis that faults in low-strain rate regions with long inter-event times rupture in higher stress drop earthquakes. We use recordings from the various GeoNet broadband stations deployed to record the ongoing
Chan, Tim Oi; Lam, Shui-Fong
2017-08-29
Raising a child with intellectual disability (ID) may be stressful for parents. Previous studies have suggested the mediating role of mindfulness in the association between child behavior problems and parental stress. The present study examined whether this mediating role is a result of parents' self-report bias. It also explored whether mindfulness has a moderating role instead when child behavior problems are reported by teachers. In a questionnaire survey, 271 Chinese parents of children with ID in 6 Hong Kong special schools reported their levels of stress and mindfulness, as well as their children's behavior problems. The latter was also reported by teachers. When child behavior problems were reported by parents, parental mindfulness was a mediator between child behavior problems and parental stress. In contrast, when child behavior problems were reported by teachers, parental mindfulness was a moderator between child behavior problems and parental stress. The mediation role of mindfulness maybe an artifact of measurement. The findings provide an encouraging message that parenting a child with ID and behavior problems does not necessarily mean more stress among all parents. Parents with a high level of mindfulness may experience less stress than those with a low level of mindfulness. Parents of children with intellectual disability (ID) tend to report high psychological stress. Previous self-report studies have identified mindfulness as a mediator in the association between child behavior problems and parental stress. The present study differs from previous studies by including third-party's reports. It has contributed to the existing body of knowledge in two respects. First, it examined whether the mediation effect resulted from parent self-report bias. Second, it tested an alternative hypothesis of the moderation effect by using teachers' reports to measure child behavior problems. The results showed that when child behavior problems were measured by parents
Application of the complex scaling method in solving three-body Coulomb scattering problem
Lazauskas, R.
2017-03-01
The three-body scattering problem in Coulombic systems is a widespread, yet unresolved problem using the mathematically rigorous methods. In this work this long-term challenge has been undertaken by combining distorted waves and Faddeev–Merkuriev equation formalisms in conjunction with the complex scaling technique to overcome the difficulties related with the boundary conditions. Unlike the common belief, it is demonstrated that the smooth complex scaling method can be applied to solve the three-body Coulomb scattering problem in a wide energy region, including the fully elastic domain and extending to the energies well beyond the atom ionization threshold. A newly developed method is used to study electron scattering on the ground states of hydrogen and positronium atoms as well as a {e}++{{H}}({n}=1)\\rightleftarrows {{p}}+{Ps}({n}=1) reaction. Where available, obtained results are compared with the experimental data and theoretical predictions, proving the accuracy and efficiency of the newly developed method.
A Novel Deflection Method for Measuring the Growth Stress of Thermally Growing Oxide Scales
无
2003-01-01
A kind of new deflection technique has been developed for measuring the growth stress of thermally growing oxide scales duringhigh temperature oxidation of alloys. The average growth stresses in oxide scales such as Al2O3, NiO and Cr2O3 formed onthe surface of the superalloys can be investigated by this technique. Unlike the comventional deflection method, the novelmethod does not need to apply a coating for preventing one main face of thin strip specimen from oxidizing and can be usedunaer tne condition of longer time and higher temperature.
He, Qiang; Hu, Xiangtao; Ren, Hong; Zhang, Hongqi
2015-11-01
A novel artificial fish swarm algorithm (NAFSA) is proposed for solving large-scale reliability-redundancy allocation problem (RAP). In NAFSA, the social behaviors of fish swarm are classified in three ways: foraging behavior, reproductive behavior, and random behavior. The foraging behavior designs two position-updating strategies. And, the selection and crossover operators are applied to define the reproductive ability of an artificial fish. For the random behavior, which is essentially a mutation strategy, the basic cloud generator is used as the mutation operator. Finally, numerical results of four benchmark problems and a large-scale RAP are reported and compared. NAFSA shows good performance in terms of computational accuracy and computational efficiency for large scale RAP.
Abbas v Y.A. Bayati
2010-01-01
Full Text Available Problem statement: The scaled hybrid Conjugate Gradient (CG algorithm which usually used for solving non-linear functions was presented and was compared with two standard well-Known NAG routines, yielding a new fast comparable algorithm. Approach: We proposed, a new hybrid technique based on the combination of two well-known scaled (CG formulas for the quadratic model in unconstrained optimization using exact line searches. A global convergence result for the new technique was proved, when the Wolfe line search conditions were used. Results: Computational results, for a set consisting of 1915 combinations of (unconstrained optimization test problems/dimensions were implemented in this research making a comparison between the new proposed algorithm and the other two similar algorithms in this field. Conclusion: Our numerical results showed that this new scaled hybrid CG-algorithm substantially outperforms Andrei-sufficient descent condition (CGSD algorithm and the well-known Andrei standard sufficient descent condition from (ACGA algorithm.
Currie, Cheryl; Wild, T Cameron; Schopflocher, Donald; Laing, Lory
2015-06-24
1) To examine associations between racial discrimination and drug problems among urban-based Aboriginal adults; and 2) to determine whether these associations are best explained by symptoms of psychological stress, distress or post-traumatic stress disorder (PTSD). Data were collected through in-person surveys with a community-based sample of Aboriginal adults (N = 372) living in a mid-sized city in western Canada in 2010. Associations were examined using bootstrapped linear regression models adjusted for confounders, with continuous prescription and illicit drug problem scores as outcomes. Mediation was examined using the cross-products of coefficients method. More than 80% of Aboriginal adults had experienced racial discrimination in the past year, with the majority reporting high levels in that period. Past-year discrimination was a risk factor for PTSD symptoms and prescription drug problems in models adjusted for confounders and other forms of psychological trauma. In mediation models, PTSD symptoms explained the association between discrimination and prescription drug problems; psychological stress and distress did not. PTSD symptoms also explained this association when the covariance between mediators was controlled. The results also indicate that participation in Aboriginal cultural traditions was associated with increased discrimination. Most efforts to address Aboriginal health inequities in Canada have focused on the role Aboriginal people play in these disparities. The current findings combine with others to call for an expanded focus. Non-Aboriginal Canadians may also play a role in the health inequities observed. The findings of this study suggest efforts to reduce discrimination experienced by Aboriginal adults in cities may reduce PTSD symptomology and prescription drug problems in these populations.
Developing and validating the Youth Conduct Problems Scale-Rwanda: a mixed methods approach.
Lauren C Ng
Full Text Available This study developed and validated the Youth Conduct Problems Scale-Rwanda (YCPS-R. Qualitative free listing (n = 74 and key informant interviews (n = 47 identified local conduct problems, which were compared to existing standardized conduct problem scales and used to develop the YCPS-R. The YCPS-R was cognitive tested by 12 youth and caregiver participants, and assessed for test-retest and inter-rater reliability in a sample of 64 youth. Finally, a purposive sample of 389 youth and their caregivers were enrolled in a validity study. Validity was assessed by comparing YCPS-R scores to conduct disorder, which was diagnosed with the Mini International Neuropsychiatric Interview for Children, and functional impairment scores on the World Health Organization Disability Assessment Schedule Child Version. ROC analyses assessed the YCPS-R's ability to discriminate between youth with and without conduct disorder. Qualitative data identified a local presentation of youth conduct problems that did not match previously standardized measures. Therefore, the YCPS-R was developed solely from local conduct problems. Cognitive testing indicated that the YCPS-R was understandable and required little modification. The YCPS-R demonstrated good reliability, construct, criterion, and discriminant validity, and fair classification accuracy. The YCPS-R is a locally-derived measure of Rwandan youth conduct problems that demonstrated good psychometric properties and could be used for further research.
Hierarchy problem, gauge coupling unification at the Planck scale, and vaccum stability
Haba, Naoyuki; Takahashi, Ryo; Yamaguchi, Yuya
2014-01-01
Regarding to the gauge hierarchy problem, an intermediate scale, such as a grand unification scale of ${\\cal O}(10^{16})\\,{\\rm GeV}$, is disfavored, and allowed mass scale is only TeV scale. For this motivation, we explore possibilities of gauge coupling unification (GCU) at the Planck scale ($M_{Pl} = 2.4 \\times 10^{18}\\,{\\rm GeV}$) by adding a few extra particles with TeV scale mass into the standard model. We find that, when all extra particles have the same mass, the GCU at the Planck scale cannot be realized only by extra fermions, but can be done by extra particles including some scalars. On the other hand, when extra fermions have different masses, the GCU can be realized around $\\sqrt{8 \\pi} M_{Pl}$ only by themselves. By this extension, a vacuum becomes stable up to the Planck scale as well as a proton lifetime is much longer than an experimental lower bound.
Measurement invariance of the Depression Anxiety Stress Scales-21 across medical student genders.
Jafari, Peyman; Nozari, Farnoosh; Ahrari, Forooghosadat; Bagheri, Zahra
2017-03-30
This study aimed to assess whether male and female Iranian medical students perceived the meaning of the items in the Depression Anxiety Stress Scales-21 consistently. A convenience sample of 783 preclinical medical students from the first to sixth semester was invited to this cross-sectional study. Of the 477 respondents, 238 were male and 239 were female. All participants completed the Persian version of the Depression Anxiety Stress Scales-21. The graded response model was used to assess measurement invariance of the instrument across the gender groups. Categorical confirmatory factor analysis was used to evaluate the construct validity of the measure. Moreover, internal consistency was assessed via Cronbach's Alpha. Statistically significant differential item functioning was flagged for just item 6 in the depression subscales (c(2)=6.5, df=1, p=0.011). However, removing or retaining the item 6 in the stress subscale did not change our findings significantly, when we compared stress scores across two genders. The results of categorical confirmatory factor analysis supported the fit of the three-factor model of Depression Anxiety Stress Scales-21. Moreover, Cronbach's alpha was greater than 0.7 in depression, anxiety and stress subscales. This study revealed that Depression Anxiety Stress Scales-21 is an invariant measure across male and female medical students. Hence, this reliable and valid instrument can be used for meaningful comparison of distress scores between medical student genders. Gender comparisons of medical students' psychological profiles provide a better insight into gender influences on the outcome of medical education and medical practice.
Barbone, Paul E; Rivas, Carlos E [College of Engineering, Boston University, Boston, MA (United States); Harari, Isaac; Albocher, Uri [Faculty of Engineering, Tel Aviv University, 69978 Ramat Aviv (Israel); Oberai, Assad A; Goenzen, Sevan [Mechanical, Aerospace, and Nuclear Engineering, Rensselaer Polytechnic Inst., Troy, NY (United States)], E-mail: barbone@bu.edu, E-mail: harari@eng.tau.ac.il, E-mail: oberaa@rpi.edu
2008-11-01
We describe a novel variational formulation of the inverse elasticity problem given interior data. The strong form of this problem is governed by equations of pure advective transport. To address this problem, we generalize the adjoint-weighted variational equation (AWE) formulation, originally developed for flow of a passive scalar. Here, we shall study the properties of the AWE formulation in the context of inverse plane stress elasticity imaging. We show that the solution of the AWE formulation is equivalent to that of the strong form when both are well posed. We prove that the Galerkin discretization of the AWE formulation leads to a stable, convergent numerical method, and prove optimal rates of convergence.
Hierarchy problem, gauge coupling unification at the Planck scale, and vacuum stability
Naoyuki Haba
2015-11-01
Full Text Available From the point of view of the gauge hierarchy problem, introducing an intermediate scale in addition to TeV scale and the Planck scale (MPl=2.4×1018 GeV is unfavorable. In that way, a gauge coupling unification (GCU is expected to be realized at MPl. We explore possibilities of GCU at MPl by adding a few extra particles with TeV scale mass into the standard model (SM. When extra particles are fermions and scalars (only fermions with the same mass, the GCU at MPl can (not be realized. On the other hand, when extra fermions have different masses, the GCU can be realized around 8πMPl without extra scalars. This simple SM extension has two advantages that a vacuum becomes stable up to MPl (8πMPl and a proton lifetime becomes much longer than an experimental bound.
Ponnet, Koen
2014-10-01
The family stress model proposes that financial stress experienced by parents is associated with problem behavior in adolescents. The present study applied an actor-partner interdependence approach to the family stress model and focused on low-, middle-, and high-income families to broaden our understanding of the pathways by which the financial stress of mothers and fathers are related to adolescent outcomes. The study uses dyadic data (N = 798 heterosexual couples) from the Relationship between Mothers, Fathers and Children study in which two-parent families with an adolescent between 11 and 17 years of age participated. Path-analytic results indicated that in each of the families the association between parents' financial stress and problem behavior in adolescents is mediated through parents' depressive symptoms, interparental conflict, and positive parenting. Family stress processes also appear to operate in different ways for low-, middle-, and high-income families. In addition to a higher absolute level of financial stress in low-income families, financial stress experienced by mothers and fathers in these families had significant direct and indirect effects on problem behavior in adolescents, while in middle- and high-income families only significant indirect effects were found. The financial stress of a low-income mother also had a more detrimental impact on her level of depressive feelings than it had on mothers in middle-income families. Furthermore, the study revealed gender differences in the pathways of mothers and fathers. Implications for research, clinical practice, and policy are also discussed.
Amrita Chakraborti
2013-01-01
Full Text Available Background: The occurrence of stress and stress related anxiety and depression in medical personnel are being increasingly reported in literature. The perceived stress scale (PSS is the most widely used psychological instrument for measuring the perception of stress. It is needed to assess perceived stress in our population using appropriately translated version of PSS. The objectives of study were to prepare a Bengali version of PSS-10 and to establish its psychometric properties in the study population. Materials and Methods: The study was conducted in a teaching hospital among medical students and interns ( N=37. The translated Bengali version and the original English version of PSS-10 were separately handed over to the individual subjects. The scores were compared across different subgroups and psychometric properties of the translated version were assessed using SPSS 16. Results: Internal consistency of PSS English (α=0.79 and Bengali (α=0.80 was satisfactory. Intra-rater reliability was adequate (κ>0.5 for most of the items, but showed an inadequate value (κ<0.5 for four items on the scale. After deleting these four items from the Bengali version, a new six-item PSS in Bengali was derived that showed good internal consistency (α=0.699. Conclusion: This new version needs to be validated in a larger study population. Perceived stress score using PSS-10 was considerably high in our study population, although there was no significant difference between the subgroups (male/female, intern/student.
Wolf, Erika J.; Miller, Mark W.; Orazem, Robert J.; Weierich, Mariann R.; Castillo, Diane T.; Milford, Jaime; Kaloupek, Danny G.; Keane, Terence M.
2008-01-01
This study examined the psychometric properties of the Minnesota Multiphasic Personality Inventory-2 (MMPI-2) Restructured Clinical Scales (RCSs) in individuals with posttraumatic stress disorder (PTSD) receiving clinical services at Department of Veterans Affairs medical centers. Study 1 included 1,098 men who completed the MMPI-2 and were…
Psychometric Properties of an Arabic Version of the Depression Anxiety Stress Scales (DASS)
Moussa, Miriam Taouk; Lovibond, Peter; Laube, Roy; Megahead, Hamido A.
2017-01-01
Objective: To translate and evaluate the psychometric properties of an Arabic-language version of the Depression Anxiety Stress Scales (DASS). Method: The items were translated, back translated, refined, and tested in an Australian immigrant sample (N = 220). Results: Confirmatory factor analysis showed that the Arabic DASS discriminates between…
Ng, Jonathan; Hakim, Ammar; Bhattacharjee, Amitava; Stanier, Adam; Daughton, William; Wang, Liang; Germaschewski, Kai
2015-01-01
As modeling of collisionless magnetic reconnection in most space plasmas with realistic parameters is beyond the capability of today's simulations, due to the separation between global and kinetic length scales, it is important to establish scaling relations in model problems so as to extrapolate to realistic scales. Recently, large scale particle-in-cell (PIC) simulations of island coalescence have shown that the time averaged reconnection rate decreases with system size, while fluid systems at such large scales in the Hall regime have not been studied. Here we perform the complementary resistive MHD, Hall MHD and two fluid simulations using a ten-moment model with the same geometry. In contrast to the standard Harris sheet reconnection problem, Hall MHD is insufficient to capture the physics of the reconnection region. Additionally, motivated by the results of a recent set of hybrid simulations which show the importance of ion kinetics in this geometry, we evaluate the efficacy of the ten-moment model in re...
Sparse deconvolution for the large-scale ill-posed inverse problem of impact force reconstruction
Qiao, Baijie; Zhang, Xingwu; Gao, Jiawei; Liu, Ruonan; Chen, Xuefeng
2017-01-01
Most previous regularization methods for solving the inverse problem of force reconstruction are to minimize the l2-norm of the desired force. However, these traditional regularization methods such as Tikhonov regularization and truncated singular value decomposition, commonly fail to solve the large-scale ill-posed inverse problem in moderate computational cost. In this paper, taking into account the sparse characteristic of impact force, the idea of sparse deconvolution is first introduced to the field of impact force reconstruction and a general sparse deconvolution model of impact force is constructed. Second, a novel impact force reconstruction method based on the primal-dual interior point method (PDIPM) is proposed to solve such a large-scale sparse deconvolution model, where minimizing the l2-norm is replaced by minimizing the l1-norm. Meanwhile, the preconditioned conjugate gradient algorithm is used to compute the search direction of PDIPM with high computational efficiency. Finally, two experiments including the small-scale or medium-scale single impact force reconstruction and the relatively large-scale consecutive impact force reconstruction are conducted on a composite wind turbine blade and a shell structure to illustrate the advantage of PDIPM. Compared with Tikhonov regularization, PDIPM is more efficient, accurate and robust whether in the single impact force reconstruction or in the consecutive impact force reconstruction.
Ng, Jonathan; Huang, Yi-Min; Hakim, Ammar; Bhattacharjee, A. [Center for Heliophysics, Princeton Plasma Physics Laboratory, Princeton, New Jersey 08540 (United States); Stanier, Adam; Daughton, William [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Wang, Liang; Germaschewski, Kai [Space Science Center and Physics Department, University of New Hampshire, Durham, New Hampshire 03824 (United States)
2015-11-15
As modeling of collisionless magnetic reconnection in most space plasmas with realistic parameters is beyond the capability of today's simulations, due to the separation between global and kinetic length scales, it is important to establish scaling relations in model problems so as to extrapolate to realistic scales. Recently, large scale particle-in-cell simulations of island coalescence have shown that the time averaged reconnection rate decreases with system size, while fluid systems at such large scales in the Hall regime have not been studied. Here, we perform the complementary resistive magnetohydrodynamic (MHD), Hall MHD, and two fluid simulations using a ten-moment model with the same geometry. In contrast to the standard Harris sheet reconnection problem, Hall MHD is insufficient to capture the physics of the reconnection region. Additionally, motivated by the results of a recent set of hybrid simulations which show the importance of ion kinetics in this geometry, we evaluate the efficacy of the ten-moment model in reproducing such results.
Efficient numerical methods for the large-scale, parallel solution of elastoplastic contact problems
Frohne, Jörg
2015-08-06
© 2016 John Wiley & Sons, Ltd. Quasi-static elastoplastic contact problems are ubiquitous in many industrial processes and other contexts, and their numerical simulation is consequently of great interest in accurately describing and optimizing production processes. The key component in these simulations is the solution of a single load step of a time iteration. From a mathematical perspective, the problems to be solved in each time step are characterized by the difficulties of variational inequalities for both the plastic behavior and the contact problem. Computationally, they also often lead to very large problems. In this paper, we present and evaluate a complete set of methods that are (1) designed to work well together and (2) allow for the efficient solution of such problems. In particular, we use adaptive finite element meshes with linear and quadratic elements, a Newton linearization of the plasticity, active set methods for the contact problem, and multigrid-preconditioned linear solvers. Through a sequence of numerical experiments, we show the performance of these methods. This includes highly accurate solutions of a three-dimensional benchmark problem and scaling our methods in parallel to 1024 cores and more than a billion unknowns.
Consensus properties and their large-scale applications for the gene duplication problem.
Moon, Jucheol; Lin, Harris T; Eulenstein, Oliver
2016-06-01
Solving the gene duplication problem is a classical approach for species tree inference from gene trees that are confounded by gene duplications. This problem takes a collection of gene trees and seeks a species tree that implies the minimum number of gene duplications. Wilkinson et al. posed the conjecture that the gene duplication problem satisfies the desirable Pareto property for clusters. That is, for every instance of the problem, all clusters that are commonly present in the input gene trees of this instance, called strict consensus, will also be found in every solution to this instance. We prove that this conjecture does not generally hold. Despite this negative result we show that the gene duplication problem satisfies a weaker version of the Pareto property where the strict consensus is found in at least one solution (rather than all solutions). This weaker property contributes to our design of an efficient scalable algorithm for the gene duplication problem. We demonstrate the performance of our algorithm in analyzing large-scale empirical datasets. Finally, we utilize the algorithm to evaluate the accuracy of standard heuristics for the gene duplication problem using simulated datasets.
João Luís Alves Apóstolo; Barry Allen Tanner; Cynthia Lee Arfken
2012-01-01
To determine which of three published models best characterizes the factor structure of the Portuguese version of the Depression Anxiety Stress Scales-21 and to assess its validity and reliability. Confirmatory factor analysis of Depression Anxiety and Stress Scale-21 for 1,297 adult, primary care outpatients (66.7% female, Mage = 48.57 years) comparing 3 models. The relationship between the Depression Anxiety Stress Scales-21 and the Positive and Negative Affect Schedule was analyzed. The co...
Optimal scaling of average queue sizes in an input-queued switch: an open problem
Shah, Devavrat; Tsitsiklis, John N.; Zhong, Yuan
2011-01-01
We review some known results and state a few versions of an open problem related to the scaling of the total queue size (in steady state) in an n×n input-queued switch, as a function of the port number n and the load factor ρ. Loosely speaking, the question is whether the total number of packets in queue, under either the maximum weight policy or under an optimal policy, scales (ignoring any logarithmic factors) as O(n/(1 − ρ)).
A Reduced Basis Framework: Application to large scale non-linear multi-physics problems
Daversin C.
2013-12-01
Full Text Available In this paper we present applications of the reduced basis method (RBM to large-scale non-linear multi-physics problems. We first describe the mathematical framework in place and in particular the Empirical Interpolation Method (EIM to recover an affine decomposition and then we propose an implementation using the open-source library Feel++ which provides both the reduced basis and finite element layers. Large scale numerical examples are shown and are connected to real industrial applications arising from the High Field Resistive Magnets development at the Laboratoire National des Champs Magnétiques Intenses.
Investigation of average growth stresses in Cr2O3 scales measured by a novel deflection method
钱余海; 李美栓; 刘光明; 辛丽
2002-01-01
The stress in the oxide film plays an important role to keep it intact so it is necessary to determine the stress in the oxide scale. Average growth stresses in Cr2O3 scales formed on Ni-base alloy (Ni80Cr20) at 1000℃ in air were investigated by a novel deflection technique. It is found that the growth stress in the oxide scale is basically compressive and its average order is 100MPa. The stress values are high for the thin scales and become low for thick scales after oxidized for 10h. The planar stress distribution in metals is complex. It is both compressive and tensile at the beginning of oxidation procedure, and then become only tensile during further oxidation.
Growth strains and stress relaxation in alumina scales during high temperature oxidation
Hou, P.Y.; Paulikas, A.P.; Veal, B.W.
2004-03-23
A novel X-ray technique was used, exploiting synchrotron radiation at the Advanced Photon Source at Argonne National Laboratory, to investigate the growth stresses in {alpha}-Al{sub 2}O{sub 3}. In-situ measurements of Debye-Scherrer diffraction patterns from the scale were recorded during oxidation and cooling, and the elliptical distortion of the diffraction rings was analyzed to yield the in-plane strain. Fe-28Al, Fe-40Al, Fe-40Al-0.2Hf, Fe-20Cr-10Al and Ni-50Al (at. %) were studied. Data were acquired in air at temperatures between 950-1100 C and during cool down. In all cases, the steady stage growth strain was relatively low (<0.1%) and was either tensile or compressive depending on the alloy. A higher tensile strain often existed during the initial oxidation period when transition alumina was present. Thermal stresses imposed on NiAl by reducing the sample temperature to 950 C for a period of time showed noticeable stress relaxation by creep. Different degrees of relaxation were also found during cooling depending on alloy composition and scale microstructure. On all Fe-based alloys, the first formed {alpha}-Al{sub 2}O{sub 3} was highly textured with the degree of texture decreasing with further oxidation. The relationships between stress development, scale wrinkling, oxide phase changes, and the effect of reactive element addition on growth stresses are discussed. Results are compared with other reports of growth stresses in Al{sub 2}O{sub 3} scales.
Flow stress and tribology size effects in scaled down cylinder compression
GUO Bin; GONG Feng; WANG Chun-ju; SHAN De-bin
2009-01-01
Microforming is an effective method to manufacture small metal parts. However, macro forming can not be transferred to microforming directly because of size effects. Flow stress and tribology size effects were studied. Scaled down copper T2 cylinder compression was carried out with the lubrication of castor oil and without lubrication. The results show that the flow stress decreases with decreasing the initial specimen diameter in both lubrication conditions, and the flow stress decreases by 30 MPa with the initial specimen diameter decreasing from 8 mm to 1 mm. The friction factor increases obviously with decreasing the initial specimen diameter in the case of lubricating with castor oil, and the friction factor increases by 0.11 with the initial specimen diameter decreasing from 8mm to 1mm. However, the tribology size effect is not found in the case without lubrication. The reasons of the flow stress and tribology size effects were also discussed.
A theoretical study of the stress relaxation in HMX on the picosecond time scale
Long, Yao; Chen, Jun
2015-12-01
The stress relaxation model of β-HMX on the picosecond time scale is studied by a theoretical approach. The relaxation of normal stress is contributed by lattice vibration, and the relaxation of shear stress is contributed by molecular rotation. Based on this model, the energy dissipation rule of the elastic wave and the profile of the shock wave are investigated. We find at low frequency the dissipation rate of the elastic wave is proportional to the power function of frequency, and under high speed shock loading the width of the stress relaxation zone is less than 0.3 μm there is a pressure peak with a height of 14 GPa near the wave front.
Fahr, H J
2006-01-01
Cosmological consequences of a strictly valid total energy conservation for the whole universe are investigated in this paper. Interestingly enough as one consequence of ergodically behaving universes very specific scaling laws with the diameter R of the universe can be derived for relevant cosmic quantities. Especially the 1/R^2- scaling of mass - and vacuum energy - density then automatically leads to a vanishing cosmic curvature parameter k=0 and also reveals, that for such universes no horizon problem occurs. In addition the longstanding problem of observationally indicated very low cosmic vacuum energies in contrast to the very large quantumfield estimates is easily solved when the vacuum energy density decay with 1/R^2 is taken into account reconciling presently observed vacuum energy density values with those from theoretical expectations. We also suggest why the mass of the universe can permanently increase and can in fact grow up from a Planck mass as a pure vacuum fluctuation.
Effective field theory analysis on {mu} problem in low-scale gauge mediation
Zheng Sibo, E-mail: sibozheng.zju@gmail.com [Department of Physics, Chongqing University, Chongqing 401331 (China)
2012-02-11
Supersymmetric models based on the scenario of gauge mediation often suffer from the well-known {mu} problem. In this paper, we reconsider this problem in low-scale gauge mediation in terms of effective field theory analysis. In this paradigm, all high energy input soft mass can be expressed via loop expansions. If the corrections coming from messenger thresholds are small, as we assume in this letter, then all RG evaluations can be taken as linearly approximation for low-scale supersymmetric breaking. Due to these observations, the parameter space can be systematically classified and studied after constraints coming from electro-weak symmetry breaking are imposed. We find that some old proposals in the literature are reproduced, and two new classes are uncovered. We refer to a microscopic model, where the specific relations among coefficients in one of the new classes are well motivated. Also, we discuss some primary phenomenologies.
A two-scale Stefan problem arising in a model for tree sap exudation
Konrad, Isabell; Stockie, John M
2016-01-01
The study of tree sap exudation, in which a (leafless) tree generates elevated stem pressure in response to repeated daily freeze-thaw cycles, gives rise to an interesting multi-scale problem involving heat and multiphase liquid/gas transport. The pressure generation mechanism is a cellular-level process that is governed by differential equations for sap transport through porous cell membranes, phase change, heat transport, and generation of osmotic pressure. By assuming a periodic cellular structure based on an appropriate reference cell, we derive an homogenized heat equation governing the global temperature on the scale of the tree stem, with all the remaining physics relegated to equations defined on the reference cell. We derive a corresponding strong formulation of the limit problem and use it to design an efficient numerical solution algorithm. Numerical simulations are then performed to validate the results and draw conclusions regarding the phenomenon of sap exudation, which is of great importance in...
A deﬁcit scaling algorithm for the minimum ﬂow problem
Laura Ciupală
2006-06-01
In this paper, we develop a new preﬂow algorithm for the minimum ﬂow problem, called deﬁcit scaling algorithm. This is a special implementation of the generic preﬂow algorithm for the minimum ﬂow problem developed by Ciurea and Ciupală earlier. The bottleneck operation in the generic preﬂow algorithm is the number of noncancelling pulls. Using the scaling technique (i.e. selecting the active nodes with sufﬁciently large deﬁcits), we reduce the number of noncancelling pulls to $O(n^2 \\log \\bar{c})$ and obtain an $O(nm+n^2 \\log \\bar{c})$ algorithm.
Goodman, S H; Gravitt, G W; Kaslow, N J
1995-08-01
The social problem-solving skill of generating effective alternative solutions was tested as a moderator of the relation between negative life stress and depressed mood in children. Boys (n = 25) and girls (n = 25), ages 8 to 12 years, from inner-city, lower socioeconomic group families, completed measures of depression symptoms, negative impact of life events, and quantity and effectiveness of alternative solutions to social problems. Results indicated that the effectiveness of alternative solutions children generate in response to peer social problems moderates the relation between stress and depression. Children who experienced a high impact of negative life events, with less effective social problem-solving skills, reported higher levels of depression compared to children who experienced a high impact of negative life events but exhibited more effective social problem-solving skills. Results are discussed in terms of alternative theoretical models for the mechanisms whereby effective social problem-solving skills moderate stress-related depression.
Depression, Anxiety and Stress Scale in patients with tinnitus and hearing loss.
Gomaa, Mohammed Abdel Motaal; Elmagd, Manal Hassan Abo; Elbadry, Mohammed Mohammed; Kader, Rafeek Mohammed Abdel
2014-08-01
The study was proposed to evaluate co-morbid depression, anxiety and stress associated with tinnitus patients. The study was done on 196 subjects: 100 patients suffering from subjective tinnitus associated with hearing loss (tinnitus group), 45 patients suffering from hearing loss only (hearing loss group) and 50 healthy subjects not suffering from tinnitus or hearing loss (control group); the age ranges from 20 to 60 years old. The studied sample was subjected to full ear, nose and throat examinations and audiological evaluation. Depression, Anxiety and Stress Scale (DASS) was developed by Levibond H and Levibond F to assess three self-report scales designed to measure the negative emotional status of depression, anxiety and stress. All patients and control group were evaluated by DASS. (1) Depression: males were affected more than females. All patients over 60 years were affected by depression. The duration of tinnitus seems correlating with the severity of depression. Only 2 patients (4.3 %) of the hearing loss group suffer from depression. (2) Anxiety: 90 % of males suffer from anxiety as compared to 83.3 % females. The age group 20-29 years old suffers more than other age groups. Only 4 patients (8.7 %) of hearing loss group suffer from anxiety. (3) Stress: females seem to be affected by the stress (76.7 %) more than males (67.5). Patients in age group 30-39 suffer the most from the disease. There is a direct correlation between duration of tinnitus and severity of stress. No one of the hearing loss group suffers from stress. In conclusion, depression, anxiety and stress should be taken into consideration in the treatment of patients suffering from tinnitus.
Nakamura, M.; Meier, D. L.
2009-08-01
What can we expect in the VSOP-2 mission to reveal the sub parsec scale structures of AGN jets? Based on the MHD process of jet formation and evolution, we discuss about unsolved problems of sub parsec AGN jets in terms of the acceleration, the collimation, and the stability properties. Several key features will be proved by the VSOP-2 observations; they play an important role in determining how the MHD process will work in the jet dynamics.
A unified solution to the small scale problems of the $\\Lambda$CDM model
Del Popolo, A; Fabris, Julio C; Rodrigues, Davi C
2014-01-01
We study, by means of the model proposed in Del Popolo (2009), the effect of baryon physics on the small scale problems of the CDM model. We show that, using this model, the cusp/core problem, the missing satellite problem (MSP), the Too Big to Fail (TBTF) problem, and the angular momentum catastrophe can be reconciled with observations. Concerning the cusp/core problem, the interaction among dark matter (DM) and baryonic clumps of 1% the mass of the halo, through dynamical friction (DF), is able to flatten the inner cusp of the density profiles. We moreover assume that haloes form primarily through quiescent accretion, in agreement with the spherical collapse model (SCM)-secondary infall model (SIM) prescriptions. The results of this paper follow from the two assumptions above. Concerning the MSP and TBTF problem, applying to the Via Lactea II (VL2) subhaloes a series of corrections similar to those of Brooks et al. (2013), namely applying a Zolotov et al. (2012)-like correction obtained with our model, and ...
A Two-Scale Discretization Scheme for Mixed Variational Formulation of Eigenvalue Problems
Yidu Yang
2012-01-01
Full Text Available This paper discusses highly efficient discretization schemes for mixed variational formulation of eigenvalue problems. A new finite element two-scale discretization scheme is proposed by combining the mixed finite element method with the shifted-inverse power method for solving matrix eigenvalue problems. With this scheme, the solution of an eigenvalue problem on a fine grid Kh is reduced to the solution of an eigenvalue problem on a much coarser grid KH and the solution of a linear algebraic system on the fine grid Kh. Theoretical analysis shows that the scheme has high efficiency. For instance, when using the Mini element to solve Stokes eigenvalue problem, the resulting solution can maintain an asymptotically optimal accuracy by taking H=O(h4, and when using the Pk+1-Pk element to solve eigenvalue problems of electric field, the calculation results can maintain an asymptotically optimal accuracy by taking H=O(h3. Finally, numerical experiments are presented to support the theoretical analysis.
Solving a real-life large-scale energy management problem
Godskesen, Steffen; Kjeldsen, Niels; Larsen, Rune
2010-01-01
This paper introduces a three-phase heuristic approach for a large-scale energy management and maintenance scheduling problem. The problem is concerned with scheduling maintenance and refueling for nuclear power plants up to five years into the future, while handling a number of scenarios for future demand and prices. The goal is to minimize the expected total production costs. The first phase of the heuristic solves a simplified constraint programming model of the problem, the second performs a local search, and the third handles overproduction in a greedy fashion. This work was initiated in the context of the ROADEF/EURO Challenge 2010, a competition organized jointly by the French Operational Research and Decision Support Society, the European Operational Research Society, and the European utility company Electricite de France. In the concluding phase of the competition our team ranked second in the junior category and sixth overall. After correcting an implementation bug in the program that was submitted ...
FEM × DEM: a new efficient multi-scale approach for geotechnical problems with strain localization
Nguyen Trung Kien
2017-01-01
Full Text Available The paper presents a multi-scale modeling of Boundary Value Problem (BVP approach involving cohesive-frictional granular materials in the FEM × DEM multi-scale framework. On the DEM side, a 3D model is defined based on the interactions of spherical particles. This DEM model is built through a numerical homogenization process applied to a Volume Element (VE. It is then paired with a Finite Element code. Using this numerical tool that combines two scales within the same framework, we conducted simulations of biaxial and pressuremeter tests on a cohesive-frictional granular medium. In these cases, it is known that strain localization does occur at the macroscopic level, but since FEMs suffer from severe mesh dependency as soon as shear band starts to develop, the second gradient regularization technique has been used. As a consequence, the objectivity of the computation with respect to mesh dependency is restored.
[Spanish adaptation of the "Mobile Phone Problem Use Scale" for adolescent population].
López-Fernández, Olatz; Honrubia-Serrano, Ma Luisa; Freixa-Blanxart, Montserrat
2012-01-01
Problematic use of the mobile telephone is an emerging phenomenon in our society, and one which particularly affects the teenage population. Knowledge from research on the problematic use of this technology is necessary, since such use can give rise to a behavioural pattern with addictive characteristics. There are hardly any scales for measuring possible problematic use of mobile phones, and none at all adapted exclusively for the Spanish adolescent population. The scale most widely used internationally is the Mobile Phone Problem Use Scale (MPPUS). The aim of the present study is to adapt the MPPUS for use with Spanish adolescents. The Spanish version of the questionnaire was administered to a sample of 1132 adolescents aged 12 to 18. Reliability and factorial validity were comparable to those obtained in adult population, so that the measure of problematic mobile phone use in Spanish teenagers is one-dimensional. A prevalence of 14.8% of problematic users was detected.
ON THE PERSISTENCE OF TWO SMALL-SCALE PROBLEMS IN ΛCDM
Pawlowski, Marcel S. [Department of Astronomy, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106 (United States); Famaey, Benoit [Observatoire astronomique de Strasbourg, Université de Strasbourg, CNRS, UMR 7550, 11 rue de l’Université, F-67000 Strasbourg (France); Merritt, David [School of Physics and Astronomy and Center for Computational Relativity and Gravitation, Rochester Institute of Technology, 84 Lomb Memorial Drive, Rochester, NY 14623 (United States); Kroupa, Pavel, E-mail: marcel.pawlowski@case.edu [Helmholtz-Institut für Strahlen- und Kernphysik, Rheinische Friedrich-Wilhelms-Universität Bonn, Nussallee 14-16, D-53115 Bonn (Germany)
2015-12-10
We investigate the degree to which the inclusion of baryonic physics can overcome two long-standing problems of the standard cosmological model on galaxy scales: (1) the problem of satellite planes around Local Group galaxies, and (2) the “too big to fail” problem. By comparing dissipational and dissipationless simulations, we find no indication that the addition of baryonic physics results in more flattened satellite distributions around Milky-Way-like systems. Recent claims to the contrary are shown to derive in part from a non-standard metric for the degree of flattening, which ignores the satellites’ radial positions. If the full 3D positions of the satellite galaxies are considered, none of the simulations we analyze reproduce the observed flattening nor the observed degree of kinematic coherence of the Milky Way satellite system. Our results are consistent with the expectation that baryonic physics should have little or no influence on the structure of satellite systems on scales of hundreds of kiloparsecs. Claims that the “too big to fail” problem can be resolved by the addition of baryonic physics are also shown to be problematic.
A modified priority list-based MILP method for solving large-scale unit commitment problems
Ke, Xinda; Lu, Ning; Wu, Di; Kintner-Meyer, Michael CW
2015-07-26
This paper studies the typical pattern of unit commitment (UC) results in terms of generator’s cost and capacity. A method is then proposed to combine a modified priority list technique with mixed integer linear programming (MILP) for UC problem. The proposed method consists of two steps. At the first step, a portion of generators are predetermined to be online or offline within a look-ahead period (e.g., a week), based on the demand curve and generator priority order. For the generators whose on/off status is predetermined, at the second step, the corresponding binary variables are removed from the UC MILP problem over the operational planning horizon (e.g., 24 hours). With a number of binary variables removed, the resulted problem can be solved much faster using the off-the-shelf MILP solvers, based on the branch-and-bound algorithm. In the modified priority list method, scale factors are designed to adjust the tradeoff between solution speed and level of optimality. It is found that the proposed method can significantly speed up the UC problem with minor compromise in optimality by selecting appropriate scale factors.
Faneca Sanchez, Marta; Sutanudjaja, Edwin; Kuijper, Marijn; Bierkens, Marc
2016-04-01
Groundwater is an invisible but indispensable resource for the economic development of many countries. Due to the need for this resource, in many cases it is exploited under severe pressure and the exploitation can become not sustainable. The non-sustainable exploitation of water is a well-known problem on both regional and global scales. However, most currently-available assessments on water stress still mostly focus on surface water and on water balances. In this work, we presented two global maps of groundwater risk indicators: an updated version of the groundwater stress (Gleeson et al., 2011, DOI: 10.1038/nature11295) and an indicator on groundwater table decline for the period 1990-2010. To calculate both indicators, we used the updated PCR-GLOBWB model output at 5 arcmin resolution (about 10 km at the equator), that is extended with an offline coupling to a global groundwater MODFLOW model. PCR-GLOBWB simulates daily river discharge and groundwater recharge, as well as surface water and groundwater abstraction rates. The latter are estimated internally within the model based on the simulation of their availabilities and water demands for irrigation and other sectors. The daily output of PCR-GLOBWB would then be aggregated to the monthly resolution and used to force the MODFLOW groundwater model resolving spatio-temporal groundwater table dynamics, incorporating the simulated groundwater abstraction of PCR-GLOBWB. Using the PCR-GLOBWB and MODFLOW simulation results from the period 1990-2010, we then quantified groundwater stress and assessed the groundwater table decline. Results are presented on four different spatial scales: 5 arcmin pixel, drainage/sub-catchment unit, state level, and major aquifer unit. The maps clearly show where groundwater is under stress, where there is a trend in the drop of the groundwater table, the slope of the drop and the significance of it.
Reliability and Characteristics of Wafer-Level Chip-Scale Packages under Current Stress
Chen, Po-Ying; Kung, Heng-Yu; Lai, Yi-Shao; Hsiung Tsai, Ming; Yeh, Wen-Kuan
2008-02-01
In this work, we present a novel approach and method for elucidating the characteristics of wafer-level chip-scale packages (WLCSPs) for electromigration (EM) tests. The die in WLCSP was directly attached to the substrate via a soldered interconnect. The shrinking of the area of the die that is available for power, and the solder bump also shrinks the volume and increases the density of electrons for interconnect efficiency. The bump current density now approaches to 106 A/cm2, at which point the EM becomes a significant reliability issue. As known, the EM failure depends on numerous factors, including the working temperature and the under bump metallization (UBM) thickness. A new interconnection geometry is adopted extensively with moderate success in overcoming larger mismatches between the displacements of components during current and temperature changes. Both environments and testing parameters for WLCSP are increasingly demanded. Although failure mechanisms are considered to have been eliminated or at least made manageable, new package technologies are again challenging its process, integrity and reliability. WLCSP technology was developed to eliminate the need for encapsulation to ensure compatibility with smart-mount technology (SMT). The package has good handing properties but is now facing serious reliability problems. In this work, we investigated the reliability of a WLCSP subjected to different accelerated current stressing conditions at a fixed ambient temperature of 125 °C. A very strong correlation exists between the mean time to failure (MTTF) of the WLCSP test vehicle and the mean current density that is carried by a solder joint. A series of current densities were applied to the WLCSP architecture; Black's power law was employed in a failure mode simulation. Additionally, scanning electron microscopy (SEM) was adopted to determine the differences existing between high- and low-current-density failure modes.
Currie, Cheryl L; Wild, T Cameron; Schopflocher, Donald P; Laing, Lory; Veugelers, Paul; Parlee, Brenda
2013-09-01
Little is known about risk factors for problem gambling (PG) within the rapidly growing urban Aboriginal population in North America. Racial discrimination may be an important risk factor for PG given documented associations between racism and other forms of addictive behaviour. This study examined associations between racial discrimination and problem gambling among urban Aboriginal adults, and the extent to which this link was mediated by post traumatic stress. Data were collected via in-person surveys with a community-based sample of Aboriginal adults living in a mid-sized city in western Canada (N = 381) in 2010. Results indicate more than 80 % of respondents experienced discrimination due to Aboriginal race in the past year, with the majority reporting high levels of racism in that time period. Past year racial discrimination was a risk factor for 12-month problem gambling, gambling to escape, and post traumatic stress disorder (PTSD) symptoms in bootstrapped regression models adjusted for confounders and other forms of social trauma. Elevated PTSD symptoms among those experiencing high levels of racism partially explained the association between racism and the use of gambling to escape in statistical models. These findings are the first to suggest racial discrimination may be an important social determinant of problem gambling for Aboriginal peoples. Gambling may be a coping response that some Aboriginal adults use to escape the negative emotions associated with racist experiences. Results support the development of policies to reduce racism directed at Aboriginal peoples in urban areas, and enhanced services to help Aboriginal peoples cope with racist events.
Elhai, Jon D.; Naifeh, James A.; Zucker, Irene S.; Gold, Steven N.; Deitsch, Sarah E.; Frueh, B. Christopher
2004-01-01
The Infrequency-Posttraumatic Stress Disorder scale (Fptsd), recently created for the Minnesota Multiphasic Personality Inventory-2 (MMPI-2), has demonstrated incremental validity over other MMPI-2 scales in malingered posttraumatic stress disorder (PTSD) detection. Fptsd was developed with combat-exposed PTSD patients, potentially limiting its…
Fang SU; Jun-zhi CUI; Zhan XU
2009-01-01
The purpose of this paper is to solve nonselfadjoint elliptic problems with rapidly oscillatory coefficients. A two-order and two-scale approximate solution expression for nonselfadjoint elliptic problems is considered, and the error estimation of the two-order and two-scale approximate solution is derived. The numerical result shows that the presented approximation solution is effective.
Worthen, Miranda; Rathod, Sujit D; Cohen, Gregory; Sampson, Laura; Ursano, Robert; Gifford, Robert; Fullerton, Carol; Galea, Sandro; Ahern, Jennifer
2014-08-01
Anger is a common problem among veterans and has been associated with posttraumatic stress disorder (PTSD). This study aimed to improve understanding of how anger and PTSD co-occur by examining gender differences and differences by whether the triggering traumatic event is deployment-related vs. civilian-related in current service members. A representative cohort of Reserve and National Guard service personnel (n = 1293) were interviewed to assess for deployment- or civilian-related traumas, PTSD, and anger. The prevalence of self-reported anger problems was estimated among male (n = 1036) and female (n = 257) service members. Log Poisson regression models with robust standard errors were used to estimate the associations of problems with anger with PTSD and PTSD symptom severity for men and women. Self-reported anger problems were common among male (53.0%) and female (51.3%) service members. Adjusted prevalence ratios (PR) showed associations between anger and PTSD connected to both civilian- and deployment-related traumas (PR were 1.77 (95% CI 1.52-2.05) and 1.85 (95% CI 1.62-2.12), respectively). PTSD symptom severity was also associated with anger. This study was cross-sectional and so a causal relationship between PTSD and anger cannot be established. Problems with anger are common among male and female current Guard and Reserve members. These findings suggest that anger treatment should be made available to current service members and that clinicians should assess anger problems irrespective of gender. Future research should examine the effectiveness of anger treatment protocols by gender.
Solving the three-body Coulomb breakup problem using exterior complex scaling
McCurdy, C.W.; Baertschy, M.; Rescigno, T.N.
2004-05-17
Electron-impact ionization of the hydrogen atom is the prototypical three-body Coulomb breakup problem in quantum mechanics. The combination of subtle correlation effects and the difficult boundary conditions required to describe two electrons in the continuum have made this one of the outstanding challenges of atomic physics. A complete solution of this problem in the form of a ''reduction to computation'' of all aspects of the physics is given by the application of exterior complex scaling, a modern variant of the mathematical tool of analytic continuation of the electronic coordinates into the complex plane that was used historically to establish the formal analytic properties of the scattering matrix. This review first discusses the essential difficulties of the three-body Coulomb breakup problem in quantum mechanics. It then describes the formal basis of exterior complex scaling of electronic coordinates as well as the details of its numerical implementation using a variety of methods including finite difference, finite elements, discrete variable representations, and B-splines. Given these numerical implementations of exterior complex scaling, the scattering wave function can be generated with arbitrary accuracy on any finite volume in the space of electronic coordinates, but there remains the fundamental problem of extracting the breakup amplitudes from it. Methods are described for evaluating these amplitudes. The question of the volume-dependent overall phase that appears in the formal theory of ionization is resolved. A summary is presented of accurate results that have been obtained for the case of electron-impact ionization of hydrogen as well as a discussion of applications to the double photoionization of helium.
TOPICAL REVIEW: Solving the three-body Coulomb breakup problem using exterior complex scaling
McCurdy, C. W.; Baertschy, M.; Rescigno, T. N.
2004-09-01
Electron-impact ionization of the hydrogen atom is the prototypical three-body Coulomb breakup problem in quantum mechanics. The combination of subtle correlation effects and the difficult boundary conditions required to describe two electrons in the continuum have made this one of the outstanding challenges of atomic physics. A complete solution of this problem in the form of a 'reduction to computation' of all aspects of the physics is given by the application of exterior complex scaling, a modern variant of the mathematical tool of analytic continuation of the electronic coordinates into the complex plane that was used historically to establish the formal analytic properties of the scattering matrix. This review first discusses the essential difficulties of the three-body Coulomb breakup problem in quantum mechanics. It then describes the formal basis of exterior complex scaling of electronic coordinates as well as the details of its numerical implementation using a variety of methods including finite difference, finite elements, discrete variable representations and B-splines. Given these numerical implementations of exterior complex scaling, the scattering wavefunction can be generated with arbitrary accuracy on any finite volume in the space of electronic coordinates, but there remains the fundamental problem of extracting the breakup amplitudes from it. Methods are described for evaluating these amplitudes. The question of the volume-dependent overall phase that appears in the formal theory of ionization is resolved. A summary is presented of accurate results that have been obtained for the case of electron-impact ionization of hydrogen as well as a discussion of applications to the double photoionization of helium.
Baik, Sharon H; Fox, Rina S; Mills, Sarah D; Roesch, Scott C; Sadler, Georgia Robins; Klonoff, Elizabeth A; Malcarne, Vanessa L
2017-01-01
This study examined the psychometric properties of the Perceived Stress Scale-10 among 436 community-dwelling Hispanic Americans with English or Spanish language preference. Multigroup confirmatory factor analysis examined the factorial invariance of the Perceived Stress Scale-10 across language groups. Results supported a two-factor model (negative, positive) with equivalent response patterns and item intercepts but different factor covariances across languages. Internal consistency reliability of the Perceived Stress Scale-10 total and subscale scores was good in both language groups. Convergent validity was supported by expected relationships of Perceived Stress Scale-10 scores to measures of anxiety and depression. These results support the use of the Perceived Stress Scale-10 among Hispanic Americans.
Tran Thach Duc; Tran Tuan; Fisher Jane
2013-01-01
Abstract Background Depression and anxiety are recognised increasingly as serious public health problems among women in low- and lower-middle income countries. The aim of this study was to validate the 21-item Depression Anxiety and Stress Scale (DASS21) for use in screening for these common mental disorders among rural women with young children in the North of Vietnam. Methods The DASS-21 was translated from English to Vietnamese, culturally verified, back-translated and administered to wome...
Lee, Keou Won; Kim, Soo Jeong; Park, Jae Beom; Lee, Kyung Jong
2011-01-01
Although increased reactive oxygen species (ROS) is caused by stress accelerates collagen degradation, there was no data on the relationship between stress and urinary hydroxyproline (Hyp) and proline (Pro), a good marker of collagen degradation. The purpose of this study was to evaluate the relationship between depression, anxiety, and stress (DAS) and concentrations of urinary Hyp and Pro. 97 hospital employees aged 20 to 58 were asked to fill out comprehensive self-administrated questionnaires containing information about their medical history, lifestyle, length of the work year, shift-work and DAS. depression anxiety stress scale (DASS) was applied to evaluate chronic mental disorders. Urine samples were analyzed using high performance liquid chromatography (HPLC) with double derivatization for the assay of hydroxyproline and proline. The mean value of Hyp and Pro concentration in all subjects was 194.1 ± 113.4 μmol/g and 568.2 ± 310.7 μmol/g. DASS values and urinary Pro concentrations were differentiated by sex (female > male, p others, p stress (Adjusted r2 = 0.051) and anxiety and job (Adjusted r2 = 0.199), respectively. We found that stress and anxiety were correlated with urinary Hyp and Pro concentrations. To identifying a definite correlation, further study in large populations will be needed.
Translation and psychometric properties of a Spanish version of the College Alcohol Problems Scale.
McCabe, Brian E; Escoto, Ernesto R; Cruz-Ortega, Luis G; Munoz-Rojas, Derby; Gattamorta, Karina
2017-12-01
Hispanic and Spanish-speaking college students are under-represented in alcohol intervention and prevention research. There is a need for brief, empirically validated Spanish versions of measures related to alcohol use and consequences. The objective of this study was to translate the 8-item College Alcohol Problems Scale (CAPS) into Spanish and evaluate the psychometric properties of this measure compared to the original English. Bilingual experts in interventions for Hispanic college students and youth used a translation back-translation process. 125 Hispanic undergraduate students from a large southeastern public university completed the CAPS and a heavy drinking measure in Spanish. The two-factor model had acceptable model fit in Spanish, χ(2) (df=19)=27.60, p=0.091; CFI=0.966 RMSEA=0.060. Internal consistency of the personal problems subscale was 0.76, and the social problems subscale was 0.73. The two latent factors explained 24-66% of variability in items. Personal problems and social problems were both significantly correlated with heavy drinking, r=0.61, pspeaking students in other nations. Copyright © 2017 Elsevier Ltd. All rights reserved.
On the Veltman Condition, the Hierarchy Problem and High-Scale Supersymmetry
Masina, Isabella
2013-01-01
In this paper we have considered the possibility that the Standard Model, and its minimal extension with the addition of singlets, merges with a high-scale supersymmetric theory at a scale satisfying the Veltman condition and therefore with no sensitivity to the cutoff. The matching of the Standard Model is achieved at Planckian scales. In its complex singlet extension the matching scale depends on the strength of the coupling between the singlet and Higgs fields. For order one values of the coupling, still in the perturbative region, the matching scale can be located in the TeV ballpark. Even in the absence of quadratic divergences there remains a finite adjustment of the parameters in the high-energy theory which should guarantee that the Higgs and the singlets in the low-energy theory are kept light. This fine-tuning (unrelated to quadratic divergences) is the entire responsibility of the ultraviolet theory and remains as the missing ingredient to provide a full solution to the hierarchy problem.
Hong Xia YIN; Dong Lei DU
2007-01-01
The self-scaling quasi-Newton method solves an unconstrained optimization problem by scaling the Hessian approximation matrix before it is updated at each iteration to avoid the possible large eigenvalues in the Hessian approximation matrices of the objective function. It has been proved in the literature that this method has the global and superlinear convergence when the objective function is convex (or even uniformly convex). We propose to solve unconstrained nonconvex optimization problems by a self-scaling BFGS algorithm with nonmonotone linear search. Nonmonotone line search has been recognized in numerical practices as a competitive approach for solving large-scale nonlinear problems. We consider two different nonmonotone line search forms and study the global convergence of these nonmonotone self-scale BFGS algorithms. We prove that, under some weaker condition than that in the literature, both forms of the self-scaling BFGS algorithm are globally convergent for unconstrained nonconvex optimization problems.
Short scales to assess cannabis-related problems: a review of psychometric properties
Klempova Danica
2008-12-01
Full Text Available Abstract Aims The purpose of this paper is to summarize the psychometric properties of four short screening scales to assess problematic forms of cannabis use: Severity of Dependence Scale (SDS, Cannabis Use Disorders Identification Test (CUDIT, Cannabis Abuse Screening Test (CAST and Problematic Use of Marijuana (PUM. Methods A systematic computer-based literature search was conducted within the databases of PubMed, PsychINFO and Addiction Abstracts. A total of 12 publications reporting measures of reliability or validity were identified: 8 concerning SDS, 2 concerning CUDIT and one concerning CAST and PUM. Studies spanned adult and adolescent samples from general and specific user populations in a number of countries worldwide. Results All screening scales tended to have moderate to high internal consistency (Cronbach's α ranging from .72 to .92. Test-retest reliability and item total correlation have been reported for SDS with acceptable results. Results of validation studies varied depending on study population and standards used for validity assessment, but generally sensitivity, specificity and predictive power are satisfactory. Standard diagnostic cut-off points that can be generalized to different populations do not exist for any scale. Conclusion Short screening scales to assess dependence and other problems related to the use of cannabis seem to be a time and cost saving opportunity to estimate overall prevalences of cannabis-related negative consequences and to identify at-risk persons prior to using more extensive diagnostic instruments. Nevertheless, further research is needed to assess the performance of the tests in different populations and in comparison to broader criteria of cannabis-related problems other than dependence.
Depression Anxiety and Stress Scales (DASS-21): psychometric analysis across four racial groups.
Norton, Peter J
2007-09-01
Growing cross-cultural awareness has led researchers to examine frequently used research instruments and assessment tools in racially diverse populations. The present study was conducted to assess the psychometric characteristics of the 21-item version of the Depression, Anxiety, and Stress Scales (DASS-21) among different racial groups. The DASS-21 was chosen because it appears to be a reliable and easy to administer measure, ideal for both clinical and research purposes. Results suggest that the internal consistency, and convergent and divergent validity of the DASS-21 are similar across racial groups. Multigroup CFA, however, indicated that item loadings were invariant, while scale covariances were not invariant. This suggests that, although the items may load similarly on the depression, anxiety and stress constructs, these constructs may be differentially inter-related across groups. Implications for application in clinical practice are discussed.
Martina Krešić Ćorić
Full Text Available Background and Objectives: Posttraumatic stress disorder (PTSD caused by war trauma experiences affects veterans'; ability to meet their parental obligations, which can lead to the appearance of psychological and behavioral problems in their children. We explored, based on the parents'; assessment, whether the children of veterans with PTSD exhibit more psychological and behavioral problems and whether there are differences in relation to the age and sex of the child. Methods: The study group consisted of 91 children from 50 veterans receiving treatment for the war-related PTSD at the Psychiatric Department of the University Clinical Hospital Mostar. The control group consisted of 98 children of 50 war veterans without PTSD who were selected from veteran associations by the snowball method. The following instruments were used in the study: General Demographic Questionnaire, Harvard Trauma Questionnaire-Bosnia and Herzegovina version and the Strengths and Difficulties Questionnaire for children. Results: Children of veterans with PTSD have more pronounced psychological and behavioral problems (U = 2372.5; P < 0.001 compared to the children of veterans without PTSD. Male children of veterans with PTSD have more frequent behavioral problems (χ² = 7.174; P = 0.025 compared to the female children, and overall, they more frequently exhibit borderline or abnormal psychological difficulties (χ² = 6.682; P = 0.029. Children exhibiting abnormal levels of hyperactivity are significantly younger than children who exhibit normal or borderline levels of hyperactivity (Kruskal-Wallis = 3.982; P = 0.046. Conclusions: The children of war veterans with PTSD have more psychological and behavioral problems in comparison with the children of veterans without PTSD.
Power scaling of a picosecond vortex laser based on a stressed Yb-doped fiber amplifier.
Koyama, Mio; Hirose, Tetsuya; Okida, Masahito; Miyamoto, Katsuhiko; Omatsu, Takashige
2011-01-17
Power scaling of a picosecond vortex laser based on a stressed Yb-doped fiber amplifier is analyzed. An output power of 25 W was obtained for 53 W of pumping, with a peak power of 37 kW. Frequency doubling of the vortex output was demonstrated using a nonlinear PPSLT crystal. A second-harmonic output power of up to 1.5 W was measured at a fundamental power of 11.2 W.
Rasch model analysis of the Depression, Anxiety and Stress Scales (DASS)
Tennant Alan; Shea Tracey L; Pallant Julie F
2009-01-01
Abstract Background There is a growing awareness of the need for easily administered, psychometrically sound screening tools to identify individuals with elevated levels of psychological distress. Although support has been found for the psychometric properties of the Depression, Anxiety and Stress Scales (DASS) using classical test theory approaches it has not been subjected to Rasch analysis. The aim of this study was to use Rasch analysis to assess the psychometric properties of the DASS-21...
Ganguly, S.; Edwards, L. [Materials Engineering, Open University, Walton Hall, Milton Keynes MK7 6AA (United Kingdom); Fitzpatrick, M.E., E-mail: m.e.fitzpatrick@open.ac.uk [Materials Engineering, Open University, Walton Hall, Milton Keynes MK7 6AA (United Kingdom)
2011-01-25
Research highlights: {yields} Comb samples used as reference samples in diffraction stress measurements on welds can retain significant macro-residual stress. {yields} Measurements of the retained residual stress have been made in a comb sample extracted from a VPPA-welded aluminium plate. {yields} A method is presented for the correction of the reference lattice parameter in the presence of retained residual stress. - Abstract: Precise measurement of a stress-free reference lattice parameter is vital in the determination of residual stress by diffraction techniques using {theta}/2{theta}-based analyses. For the evaluation of the residual strain profile in fusion-welded material, it is particularly important to correct the measured strain point-by-point by a stress-free reference for each spatial location across the weld. This is to take into account the compositional and microstructural variation across the weld caused by the thermal cycle of welding, as local changes in solute content of the parent alloy cause changes in the stress-free lattice parameter. Although ideally such measurements should be obtained from small cubes machined from the weld, the use of a comb sample has previously been proposed as a macro-stress-free reference, with the assumption that each finger of the comb is of insufficient dimension to hold a macro-stress field. This paper presents an approach towards analysis of the stress-free reference values using a comb sample extracted from a variable polarity plasma arc (VPPA) welded plate. It is shown that there is inter-granular stress and retained macro-stress within the comb teeth, and an experimental approach to deal with the problem is proposed.
Scaling of stress drop and high-frequency fall-off of source spectra
无
1999-01-01
It has been observed for a long time that the high-frequency fall-off constant of source spectra is about 2 for "large" earthquakes and about 3 for "small" earthquakes. For earthquakes between "large" and "small", the highfrequency fall-off constant is not an integer and varies with the size of the earthquake. In this article such a variation is explained in the perspective of the scaling of stress drop, which proposes a new approach to the study of the scaling of stress drop using seismic data with lower quality of completeness and high-frequency characteristics. The study on the source spectra of the aftershocks of the 1988 Lancang-Gengma, Yunnan, China earthquake shows that the high-frequency fall-off of source spectra and its variation with the size of earthquake can be well explained by the model that for "large" earthquakes the stress drop is a constant while for "small" earthquakes the stress drop increases with the size of the earthquake.
Wind-invariant saltation heights imply linear scaling of aeolian saltation flux with shear stress.
Martin, Raleigh L; Kok, Jasper F
2017-06-01
Wind-driven sand transport generates atmospheric dust, forms dunes, and sculpts landscapes. However, it remains unclear how the flux of particles in aeolian saltation-the wind-driven transport of sand in hopping trajectories-scales with wind speed, largely because models do not agree on how particle speeds and trajectories change with wind shear velocity. We present comprehensive measurements, from three new field sites and three published studies, showing that characteristic saltation layer heights remain approximately constant with shear velocity, in agreement with recent wind tunnel studies. These results support the assumption of constant particle speeds in recent models predicting linear scaling of saltation flux with shear stress. In contrast, our results refute widely used older models that assume that particle speed increases with shear velocity, thereby predicting nonlinear 3/2 stress-flux scaling. This conclusion is further supported by direct field measurements of saltation flux versus shear stress. Our results thus argue for adoption of linear saltation flux laws and constant saltation trajectories for modeling saltation-driven aeolian processes on Earth, Mars, and other planetary surfaces.
1/f and the Earthquake Problem: Scaling constraints to facilitate operational earthquake forecasting
Yoder, M. R.; Rundle, J. B.; Glasscoe, M. T.
2013-12-01
The difficulty of forecasting earthquakes can fundamentally be attributed to the self-similar, or '1/f', nature of seismic sequences. Specifically, the rate of occurrence of earthquakes is inversely proportional to their magnitude m, or more accurately to their scalar moment M. With respect to this '1/f problem,' it can be argued that catalog selection (or equivalently, determining catalog constraints) constitutes the most significant challenge to seismicity based earthquake forecasting. Here, we address and introduce a potential solution to this most daunting problem. Specifically, we introduce a framework to constrain, or partition, an earthquake catalog (a study region) in order to resolve local seismicity. In particular, we combine Gutenberg-Richter (GR), rupture length, and Omori scaling with various empirical measurements to relate the size (spatial and temporal extents) of a study area (or bins within a study area), in combination with a metric to quantify rate trends in local seismicity, to the local earthquake magnitude potential - the magnitudes of earthquakes the region is expected to experience. From this, we introduce a new type of time dependent hazard map for which the tuning parameter space is nearly fully constrained. In a similar fashion, by combining various scaling relations and also by incorporating finite extents (rupture length, area, and duration) as constraints, we develop a method to estimate the Omori (temporal) and spatial aftershock decay parameters as a function of the parent earthquake's magnitude m. From this formulation, we develop an ETAS type model that overcomes many point-source limitations of contemporary ETAS. These models demonstrate promise with respect to earthquake forecasting applications. Moreover, the methods employed suggest a general framework whereby earthquake and other complex-system, 1/f type, problems can be constrained from scaling relations and finite extents.
Gharsalli, Leila; Mohammad-Djafari, Ali; Fraysse, Aurélia; Rodet, Thomas
2013-08-01
Our aim is to solve a linear inverse problem using various methods based on the Variational Bayesian Approximation (VBA). We choose to take sparsity into account via a scale mixture prior, more precisely a student-t model. The joint posterior of the unknown and hidden variable of the mixtures is approximated via the VBA. To do this approximation, classically the alternate algorithm is used. But this method is not the most efficient. Recently other optimization algorithms have been proposed; indeed classical iterative algorithms of optimization such as the steepest descent method and the conjugate gradient have been studied in the space of the probability densities involved in the Bayesian methodology to treat this problem. The main object of this work is to present these three algorithms and a numerical comparison of their performances.
A raw material storage yard allocation problem for a large-scale steelworks
Kim, B.I.; Koo, J.; Park, B.S. [POSTECH, Pohang (Republic of Korea). Department of Industrial and Management Engineering
2009-04-15
This paper addresses a raw material storage yard allocation problem at a large-scale steelworks. At the steelworks, raw materials such as coal and iron ore are imported by ships from overseas, discharged from the ships by unloading equipment, and transported into and stored in the yards. The stored materials then are transported and used in the production equipment such as steel mills. The yard allocation decision, i.e., where to store the materials, determines the travel distance of the materials as well as the storage efficiency of the yards. Here, the yard allocation problem is solved using a mixed integer programming model. The solution compares favorably with the current practice of the steelworks.
On the solution to the Polonyi problem with no-scale type supergravity
Moroi, T.
1995-10-01
We study the solution to the Polonyi problem in the framework of no-scale type supergravity. In such a model, Polonyi field can weigh as O(10TeV) and decay just before the big-bang nucleosynthesis. It is shown that in spite of a large entropy production by the decay of the Polonyi field, one can naturally explain the present value of the baryon-to-entropy ratio, {eta}{sub B}/S {approximately} (10{sup {minus}10} {minus} 10{sup {minus}11}) if the Affleck-Dine mechanism for baryogenesis works. It is pointed out, however, that there is another cosmological problem related to the abundance of the lightest superparticles produced by the decay of the Polonyi field.
A Bayesian approach to multiscale inverse problems with on-the-fly scale determination
Ellam, Louis; Zabaras, Nicholas; Girolami, Mark
2016-12-01
A Bayesian computational approach is presented to provide a multi-resolution estimate of an unknown spatially varying parameter from indirect measurement data. In particular, we are interested in spatially varying parameters with multiscale characteristics. In our work, we consider the challenge of not knowing the characteristic length scale(s) of the unknown a priori, and present an algorithm for on-the-fly scale determination. Our approach is based on representing the spatial field with a wavelet expansion. Wavelet basis functions are hierarchically structured, localized in both spatial and frequency domains and tend to provide sparse representations in that a large number of wavelet coefficients are approximately zero. For these reasons, wavelet bases are suitable for representing permeability fields with non-trivial correlation structures. Moreover, the intra-scale correlations between wavelet coefficients form a quadtree, and this structure is exploited to identify additional basis functions to refine the model. Bayesian inference is performed using a sequential Monte Carlo (SMC) sampler with a Markov Chain Monte Carlo (MCMC) transition kernel. The SMC sampler is used to move between posterior densities defined on different scales, thereby providing a computationally efficient method for adaptive refinement of the wavelet representation. We gain insight from the marginal likelihoods, by computing Bayes factors, for model comparison and model selection. The marginal likelihoods provide a termination criterion for our scale determination algorithm. The Bayesian computational approach is rather general and applicable to several inverse problems concerning the estimation of a spatially varying parameter. The approach is demonstrated with permeability estimation for groundwater flow using pressure sensor measurements.
Time asynchronous relative dimension in space method for multi-scale problems in fluid dynamics
Markesteijn, A. P.; Karabasov, S. A.
2014-02-01
A novel computational method is presented for solving fluid dynamics equations in the multi-scale framework when the system size is an important parameter of the governing equations. The method (TARDIS) is based on a concurrent transformation of the governing equations in space and time and solving the transformed equations on a uniform Cartesian grid with the corresponding causality conditions at the grid interfaces. For implementation in the framework of TARDIS, the second-order CABARET scheme of Karabasov and Goloviznin [1] is selected for it provides a good combination of numerical accuracy, computational efficiency and simplicity of realisation. Numerical examples are first provided for several isothermal gas dynamics test problems and then for modelling of molecular fluctuations inside a microscopic flow channel and ultrasound wave propagation through a nano-scale region of molecular fluctuations.
Eskin, Mehmet; Akyol, Ali; Çelik, Emine Yilmaz; Gültekin, Bülent Kadri
2013-08-01
This study aimed at investigating social problem solving, perceived stress, depression, and life-satisfaction in patients with tension type and migraine headaches. Forty-nine migraine and 42 tension type headache patients (n = 91) consenting to participate were compared to a total of 49 matched healthy control group. Participants filled in a questionnaire consisting self-report measures of problem solving, perceived stress, depression and life satisfaction. They were also asked about headache duration, frequency, pain severity, psychiatric treatment and sense of control in one's life. T-tests, chi-square, analysis of variance, logistic regression analysis and Pearson product moment correlation coefficient procedures were used to analyze the data. Tension type headache patients reported having had more frequent headaches than the migraine patients but migraine patients reported having had more intense pain than the tension type headache patients. Instances of psychiatric treatment were more common among tension type headache patients than the migraine and the control group. Compared to the healthy controls, headache patients displayed a deficiency in problem solving, higher levels of perceived stress and depression. Levels of problem solving skills in headache patients were related inversely to depression, perceived stress and the number of negative life events but problem solving skills of headache patients was related positively to life-satisfaction. The findings from this study suggested that cognitive behavioral problem solving therapy or training might be a viable option for reducing levels of stress and depression, and to increase life-satisfaction in patients suffering from primary headache.
On large-scale nonlinear programming techniques for solving optimal control problems
Faco, J.L.D.
1994-12-31
The formulation of decision problems by Optimal Control Theory allows the consideration of their dynamic structure and parameters estimation. This paper deals with techniques for choosing directions in the iterative solution of discrete-time optimal control problems. A unified formulation incorporates nonlinear performance criteria and dynamic equations, time delays, bounded state and control variables, free planning horizon and variable initial state vector. In general they are characterized by a large number of variables, mostly when arising from discretization of continuous-time optimal control or calculus of variations problems. In a GRG context the staircase structure of the jacobian matrix of the dynamic equations is exploited in the choice of basic and super basic variables and when changes of basis occur along the process. The search directions of the bound constrained nonlinear programming problem in the reduced space of the super basic variables are computed by large-scale NLP techniques. A modified Polak-Ribiere conjugate gradient method and a limited storage quasi-Newton BFGS method are analyzed and modifications to deal with the bounds on the variables are suggested based on projected gradient devices with specific linesearches. Some practical models are presented for electric generation planning and fishery management, and the application of the code GRECO - Gradient REduit pour la Commande Optimale - is discussed.
Preservation of local linearity by neighborhood subspace scaling for solving the pre-image problem
Sheng-kai YANG; Jian-yi MENG; Hai-bin SHEN
2014-01-01
An important issue involved in kernel methods is the pre-image problem. However, it is an ill-posed problem, as the solution is usually nonexistent or not unique. In contrast to direct methods aimed at minimizing the distance in feature space, indirect methods aimed at constructing approximate equivalent models have shown outstanding performance. In this paper, an indirect method for solving the pre-image problem is proposed. In the proposed algorithm, an inverse mapping process is constructed based on a novel framework that preserves local linearity. In this framework, a local nonlinear transformation is implicitly conducted by neighborhood subspace scaling transformation to preserve the local linearity between feature space and input space. By extending the inverse mapping process to test samples, we can obtain pre-images in input space. The proposed method is non-iterative, and can be used for any kernel functions. Experimental results based on image denoising using kernel principal component analysis (PCA) show that the proposed method outperforms the state-of-the-art methods for solving the pre-image problem.
Validation of the Turkish version of the problem areas in diabetes scale
Huis In 't Veld, Elisabeth M J; Makine, Ceylan; Nouwen, Arie
2011-01-01
The Problem Areas in Diabetes (PAID) scale is a widely used self-report measure that can facilitate detection of diabetes-specific emotional distress in clinical practice. The aim of this study was to assess the factor structure and validity of the Turkish version of the PAID. A validation study...... yielded a 2-factor structure, identifying a 15-item "diabetes distress" factor and a 5-item "support-related issues" factor. The total PAID-score and the two dimensions were associated with higher levels of depression and poor emotional well-being. In the present study, the Turkish version of the PAID had...
Mapping the MMPI-2-RF Specific Problems Scales Onto Extant Psychopathology Structures.
Sellbom, Martin
2017-01-01
A main objective in developing the Minnesota Multiphasic Personality Inventory-2-Restructured Form (MMPI-2-RF; Ben-Porath & Tellegen, 2008 ) was to link the hierarchical structure of the instrument's scales to contemporary psychopathology and personality models for greater enhancement of construct validity. Initial evidence published with the Restructured Clinical scales has indicated promising results in that the higher order structure of these measures maps onto those reported in the extant psychopathology literature. This study focused on evaluating the internal structure of the Specific Problems and Interest scales, which have not yet been examined in this manner. Two large, mixed-gender outpatient and correctional samples were used. Exploratory factor analyses revealed consistent evidence for a 4-factor structure representing somatization, negative affect, externalizing, and social detachment. Convergent and discriminant validity analyses in the outpatient sample yielded a pattern of results consistent with expectations. These findings add further evidence to indicate that the MMPI-2-RF hierarchy of scales map onto extant psychopathology literature, and also add support to the notion that somatization and detachment should be considered important higher order domains in the psychopathology literature.
Wilson, Robyn S.; Hardisty, David J.; Epanchin-Niell, Rebecca S.; Runge, Michael C.; Cottingham, Kathryn L.; Urban, Dean L.; Maguire, Lynn A.; Hastings, Alan; Mumby, Peter J.; Peters, Debra P. C.
2016-01-01
Ecological systems often operate on time scales significantly longer or shorter than the time scales typical of human decision making, which causes substantial difficulty for conservation and management in socioecological systems. For example, invasive species may move faster than humans can diagnose problems and initiate solutions, and climate systems may exhibit long-term inertia and short-term fluctuations that obscure learning about the efficacy of management efforts in many ecological systems. We adopted a management-decision framework that distinguishes decision makers within public institutions from individual actors within the social system, calls attention to the ways socioecological systems respond to decision makers’ actions, and notes institutional learning that accrues from observing these responses. We used this framework, along with insights from bedeviling conservation problems, to create a typology that identifies problematic time-scale mismatches occurring between individual decision makers in public institutions and between individual actors in the social or ecological system. We also considered solutions that involve modifying human perception and behavior at the individual level as a means of resolving these problematic mismatches. The potential solutions are derived from the behavioral economics and psychology literature on temporal challenges in decision making, such as the human tendency to discount future outcomes at irrationally high rates. These solutions range from framing environmental decisions to enhance the salience of long-term consequences, to using structured decision processes that make time scales of actions and consequences more explicit, to structural solutions aimed at altering the consequences of short-sighted behavior to make it less appealing. Additional application of these tools and long-term evaluation measures that assess not just behavioral changes but also associated changes in ecological systems are needed.
Validation of Reef-Scale Thermal Stress Satellite Products for Coral Bleaching Monitoring
Scott F. Heron
2016-01-01
Full Text Available Satellite monitoring of thermal stress on coral reefs has become an essential component of reef management practice around the world. A recent development by the U.S. National Oceanic and Atmospheric Administration’s Coral Reef Watch (NOAA CRW program provides daily global monitoring at 5 km resolution—at or near the scale of most coral reefs. In this paper, we introduce two new monitoring products in the CRW Decision Support System for coral reef management: Regional Virtual Stations, a regional synthesis of thermal stress conditions, and Seven-day Sea Surface Temperature (SST Trend, describing recent changes in temperature at each location. We describe how these products provided information in support of management activities prior to, during and after the 2014 thermal stress event in the Commonwealth of the Northern Mariana Islands (CNMI. Using in situ survey data from this event, we undertake the first quantitative comparison between 5 km satellite monitoring products and coral bleaching observations. Analysis of coral community characteristics, historical temperature conditions and thermal stress revealed a strong influence of coral biodiversity in the patterns of observed bleaching. This resulted in a model based on thermal stress and generic richness that explained 97% of the variance in observed bleaching. These findings illustrate the importance of using local benthic characteristics to interpret the level of impact from thermal stress exposure. In an era of continuing climate change, accurate monitoring of thermal stress and prediction of coral bleaching are essential for stakeholders to direct resources to the most effective management actions to conserve coral reefs.
Rickenbach, Elizabeth H.; Almeida, David M.; Seeman, Teresa E.; Lachman, Margie E.
2014-01-01
We examined whether long-term fluid cognitive decline was associated with memory problems in everyday life, and whether stress plays a moderating role. We expected that the association between cognitive decline and everyday memory problems would be magnified in the context of self-reported and physiological stress. Data are from the Boston Longitudinal Study, a subsample of the Midlife in the United States study. Participants in the current study (n=112) completed a battery of tests measuring fluid cognitive functioning at Time 1 (T1) and 2 (T2) over ten years. At T2, participants completed weekly diaries of self-reported daily stressors and everyday memory problems for twelve consecutive weeks. Also at T2, participants provided four saliva samples over the course of one day to assess physiological stress using diurnal cortisol profiles [cortisol awakening response (CAR) and diurnal cortisol slope (DCS)]. Self-reported daily stressors and a less healthy DCS were associated with more everyday memory problems, and participants with greater cognitive decline reported more memory problems compared to those with less or no decline. Self-reported daily stressors and CAR moderated the relationship of cognitive decline and memory problems. As expected, more cognitive decline was associated with greater increases in memory problems on weeks when individuals reported more daily stressors and for individuals with a less healthy CAR. The current findings can inform interventions aimed to identify factors, such as daily stress, that contribute to daily functioning in the context of cognitive decline. PMID:25365691
Quesada, Andrea A; Tristão, Rosana M; Pratesi, Riccardo; Wolf, Oliver T
2014-09-01
The prevalence of preterm birth (PTB) is high worldwide, especially in developing countries like Brazil. PTB is marked by a stressful environment in intra- as well as extrauterine life, which can affect neurodevelopment and hormonal and physiological systems and lead to long-term negative outcomes. Nevertheless, little is known about PTB and related outcomes later on in childhood. Thus, the goals of the current study were threefold: (1) comparing cortisol and alpha-amylase (sAA) profiles, including cortisol awakening response (CAR), between preterm and full-term children; (2) evaluating whether preterm children are more responsive to acute stress and (3) assessing their memory skills and emotional and behavioral profiles. Basal cortisol and sAA profiles, including CAR of 30 preterm children, aged 6 to 10 years, were evaluated. Further, we assessed memory functions using the Wide Range Assessment of Memory and Learning, and we screened behavior/emotion using the Strengths and Difficulties Questionnaire. The results of preterm children were compared to an age- and sex-matched control group. One week later, participants were exposed to a standardized laboratory stressor [Trier Social Stress Test for Children (TSST-C)], in which cortisol and sAA were measured at baseline, 1, 10 and 25 min after stressor exposure. Preterm children had higher cortisol concentrations at awakening, a flattened CAR and an exaggerated response to TSST-C compared to full-term children. These alterations were more pronounced in girls. In addition, preterm children were characterized by more emotional problems and poorer memory performance. Our findings illustrate the long-lasting and in part sex-dependent effects of PTB on the hypothalamic-pituitary-adrenal (HPA) axis, internalizing behavior and memory. The findings are in line with the idea that early adversity alters the set-point of the HPA axis, thereby creating a more vulnerable phenotype.
Richman, J A; Flaherty, J A; Rospenda, K M
1996-03-01
Sociologists who embrace the stress or alienation paradigms generally focus on explaining problem drinking in low status occupations. By contrast, this paper argues that a broadened conceptualization of stress and alienation which incorporates abusive work relationships has utility for explaining male and female drinking outcomes in both high and low status occupations. We provide empirical data on the relationship between perceived abusive experiences and drinking outcomes in a cohort of male and female physicians in their internship year of training. The data show that perceived sexual harassment, discriminatory treatment and psychological humiliation relate to various drinking outcomes in men and women, controlling for drinking prior to the internship year. While females were more likely to report experiencing abuse, these perceived experiences had deleterious effects on drinking outcomes for both genders. Personal vulnerability (narcissism) brought into the training environment somewhat influenced the later reporting of abusive experiences by males but not by females. Regression analyses showed that, for both males and females, work-place abusive experiences in interaction with personality vulnerability best explained drinking outcomes. The implications of these results for the design of future alcohol-related work-place studies are discussed.
EvArnoldi: A New Algorithm for Large-Scale Eigenvalue Problems.
Tal-Ezer, Hillel
2016-05-19
Eigenvalues and eigenvectors are an essential theme in numerical linear algebra. Their study is mainly motivated by their high importance in a wide range of applications. Knowledge of eigenvalues is essential in quantum molecular science. Solutions of the Schrödinger equation for the electrons composing the molecule are the basis of electronic structure theory. Electronic eigenvalues compose the potential energy surfaces for nuclear motion. The eigenvectors allow calculation of diople transition matrix elements, the core of spectroscopy. The vibrational dynamics molecule also requires knowledge of the eigenvalues of the vibrational Hamiltonian. Typically in these problems, the dimension of Hilbert space is huge. Practically, only a small subset of eigenvalues is required. In this paper, we present a highly efficient algorithm, named EvArnoldi, for solving the large-scale eigenvalues problem. The algorithm, in its basic formulation, is mathematically equivalent to ARPACK ( Sorensen , D. C. Implicitly Restarted Arnoldi/Lanczos Methods for Large Scale Eigenvalue Calculations ; Springer , 1997 ; Lehoucq , R. B. ; Sorensen , D. C. SIAM Journal on Matrix Analysis and Applications 1996 , 17 , 789 ; Calvetti , D. ; Reichel , L. ; Sorensen , D. C. Electronic Transactions on Numerical Analysis 1994 , 2 , 21 ) (or Eigs of Matlab) but significantly simpler.
Beison, Ashley; Rademacher, David J
2017-03-01
Background and aims Smartphones are ubiquitous. As smartphones increased in popularity, researchers realized that people were becoming dependent on their smartphones. The purpose here was to provide a better understanding of the factors related to problematic smartphone use (PSPU). Methods The participants were 100 undergraduates (25 males, 75 females) whose ages ranged from 18 to 23 (mean age = 20 years). The participants completed questionnaires to assess gender, ethnicity, year in college, father's education level, mother's education level, family income, age, family history of alcoholism, and PSPU. The Family Tree Questionnaire assessed family history of alcoholism. The Mobile Phone Problem Use Scale (MPPUS) and the Adapted Cell Phone Addiction Test (ACPAT) were used to determine the degree of PSPU. Whereas the MPPUS measures tolerance, escape from other problems, withdrawal, craving, and negative life consequences, the ACPAT measures preoccupation (salience), excessive use, neglecting work, anticipation, lack of control, and neglecting social life. Results Family history of alcoholism and father's education level together explained 26% of the variance in the MPPUS scores and 25% of the variance in the ACPAT scores. The inclusion of mother's education level, ethnicity, family income, age, year in college, and gender did not significantly increase the proportion of variance explained for either MPPUS or ACPAT scores. Discussion and conclusions Family history of alcoholism and father's education level are good predictors of PSPU. As 74%-75% of the variance in PSPU scale scores was not explained, future studies should aim to explain this variance.
Backer-Fulghum, Lindsey M; Patock-Peckham, Julie A; King, Kevin M; Roufa, Lindsay; Hagen, Leslie
2012-04-01
The stress dampening model (Marlatt, 1987; Sayette, 1993; Sher, 1987) suggests certain individuals may use alcohol to escape from their negative life experiences. Pathological reasons for drinking (e.g., using alcohol as a means to cope) reflect the degree to which individuals are motivated to use alcohol in order to dampen or alleviate the stress they are experiencing (Johnson, Schwitters, Wilson, Nagoshi, & McClearn, 1985). Direct and mediational links among parental bonds (rejection, care, overprotection, autonomy, and neglect), self-esteem, stress, pathological reasons for drinking, and alcohol-related problems were explored. A Structural Equation Model with (405 students; 164 women, 241 men) college students was examined. Three path mediational analyses revealed several mediated pathways. Greater feelings of perceived father/mother neglectfulness (i.e., offspring feeling parents do not show up for them) were indirectly linked to more alcohol-related problems (e.g., indicative of alcohol use or dependence in emerging adulthood) through increased stress and pathological reasons for drinking. Furthermore, higher levels of father rejection (i.e., perception of feeling unwanted) were indirectly linked to more pathological reasons for drinking through low self-esteem and increased stress. However, greater feelings of mother care (affectionate and attentive) were indirectly linked to fewer pathological reasons for drinking through higher self-esteem and lower levels of stress. Moreover, high self-esteem was found to be indirectly linked to fewer alcohol-related problems through decreased stress and pathological reasons for drinking. These findings suggest several specific pathways for using alcohol to self-medicate (i.e., consume alcohol for a specific purpose) or dampen feelings of stress. Copyright © 2011 Elsevier Ltd. All rights reserved.
Rasch model analysis of the Depression, Anxiety and Stress Scales (DASS
Tennant Alan
2009-05-01
Full Text Available Abstract Background There is a growing awareness of the need for easily administered, psychometrically sound screening tools to identify individuals with elevated levels of psychological distress. Although support has been found for the psychometric properties of the Depression, Anxiety and Stress Scales (DASS using classical test theory approaches it has not been subjected to Rasch analysis. The aim of this study was to use Rasch analysis to assess the psychometric properties of the DASS-21 scales, using two different administration modes. Methods The DASS-21 was administered to 420 participants with half the sample responding to a web-based version and the other half completing a traditional pencil-and-paper version. Conformity of DASS-21 scales to a Rasch partial credit model was assessed using the RUMM2020 software. Results To achieve adequate model fit it was necessary to remove one item from each of the DASS-21 subscales. The reduced scales showed adequate internal consistency reliability, unidimensionality and freedom from differential item functioning for sex, age and mode of administration. Analysis of all DASS-21 items combined did not support its use as a measure of general psychological distress. A scale combining the anxiety and stress items showed satisfactory fit to the Rasch model after removal of three items. Conclusion The results provide support for the measurement properties, internal consistency reliability, and unidimensionality of three slightly modified DASS-21 scales, across two different administration methods. The further use of Rasch analysis on the DASS-21 in larger and broader samples is recommended to confirm the findings of the current study.
Helicity, geostrophic balance and mixing in rotating stratified turbulence: a multi-scale problem
Pouquet, A.; Marino, R.; Mininni, P.; Rorai, C.; Rosenberg, D. L.
2012-12-01
Helicity, geostrophic balance and mixing in rotating stratified turbulence: a multi-scale problem A. Pouquet, R. Marino, P. D. Mininni, C. Rorai & D. Rosenberg, NCAR Interactions between winds and waves have important roles in planetary and oceanic boundary layers, affecting momentum, heat and CO2 transport. Within the Abyssal Southern Ocean at Mid latitude, this may result in a mixed layer which is too shallow in climate models thereby affecting the overall evolution because of poor handling of wave breaking as in Kelvin-Helmoltz instabilities: gravity waves couple nonlinearly on slow time scales and undergo steepening through resonant interactions, or due to the presence of shear. In the oceans, sub-mesoscale frontogenesis and significant departure from quasi-geostrophy can be seen as turbulence intensifies. The ensuing anomalous vertical dispersion may not be simply modeled by a random walk, due to intermittent structures, wave propagation and to their interactions. Conversely, the energy and seeds required for such intermittent events to occur, say in the stable planetary boundary layer, may come from the wave field that is perturbed, or from winds and the effect of topography. Under the assumption of stationarity, weak nonlinearities, dissipation and forcing, one obtains large-scale geostrophic balance linking pressure gradient, gravity and Coriolis force. The role of helicity (velocity-vorticity correlations) has not received as much attention, outside the realm of astrophysics when considering the growth of large-scale magnetic fields. However, it is measured routinely in the atmosphere in order to gauge the likelihood of supercell convective storms to strengthen, and it may be a factor to consider in the formation of hurricanes. In this context, we examine the transition from a wave-dominated regime to an isotropic small-scale turbulent one in rotating flows with helical forcing. Using a direct numerical simulation (DNS) on a 3072^3 grid with Rossby and
Geyer, A.; Martí, J.; Villaseñor, A.
2016-06-01
In volcanic areas, the existing stress field is a key parameter controlling magma generation, location and geometry of the magmatic plumbing systems and the distribution of the resulting volcanism at surface. Therefore, knowing the stress configuration in the lithosphere at any scale (i.e. local, regional and plate-scale) is fundamental to understand the distribution of volcanism and, subsequently, to interpret volcanic unrest and potential tectonic controls of future eruptions. The objective of the present work is to provide a first-order estimate of the plate-scale tectonic stresses acting on the Canary Islands, one of the largest active intraplate volcanic regions of the World. In order to obtain the orientation of the minimum and maximum horizontal compressive stresses, we perform a series of 2D finite element models of plate scale kinematics assuming plane stress approximation. Results obtained are used to develop a regional model, which takes into account recognized archipelago-scale structural discontinuities. Maximum horizontal compressive stress directions obtained are compared with available stress, geological and geodynamic data. The methodology used may be easily applied to other active volcanic regions, where a first order approach of their plate/regional stresses can be essential information to be used as input data for volcanic hazard assessment models.
Parallel Optimization of Polynomials for Large-scale Problems in Stability and Control
Kamyar, Reza
In this thesis, we focus on some of the NP-hard problems in control theory. Thanks to the converse Lyapunov theory, these problems can often be modeled as optimization over polynomials. To avoid the problem of intractability, we establish a trade off between accuracy and complexity. In particular, we develop a sequence of tractable optimization problems --- in the form of Linear Programs (LPs) and/or Semi-Definite Programs (SDPs) --- whose solutions converge to the exact solution of the NP-hard problem. However, the computational and memory complexity of these LPs and SDPs grow exponentially with the progress of the sequence - meaning that improving the accuracy of the solutions requires solving SDPs with tens of thousands of decision variables and constraints. Setting up and solving such problems is a significant challenge. The existing optimization algorithms and software are only designed to use desktop computers or small cluster computers --- machines which do not have sufficient memory for solving such large SDPs. Moreover, the speed-up of these algorithms does not scale beyond dozens of processors. This in fact is the reason we seek parallel algorithms for setting-up and solving large SDPs on large cluster- and/or super-computers. We propose parallel algorithms for stability analysis of two classes of systems: 1) Linear systems with a large number of uncertain parameters; 2) Nonlinear systems defined by polynomial vector fields. First, we develop a distributed parallel algorithm which applies Polya's and/or Handelman's theorems to some variants of parameter-dependent Lyapunov inequalities with parameters defined over the standard simplex. The result is a sequence of SDPs which possess a block-diagonal structure. We then develop a parallel SDP solver which exploits this structure in order to map the computation, memory and communication to a distributed parallel environment. Numerical tests on a supercomputer demonstrate the ability of the algorithm to
Dual mean field search for large scale linear and quadratic knapsack problems
Banda, Juan; Velasco, Jonás; Berrones, Arturo
2017-07-01
An implementation of mean field annealing to deal with large scale linear and non linear binary optimization problems is given. Mean field annealing is based on the analogy between combinatorial optimization and interacting physical systems at thermal equilibrium. Specifically, a mean field approximation of the Boltzmann distribution given by a Lagrangian that encompass the objective function and the constraints is calculated. The original discrete task is in this way transformed into a continuous variational problem. In our version of mean field annealing, no temperature parameter is used, but a good starting point in the dual space is given by a ;thermodynamic limit; argument. The method is tested in linear and quadratic knapsack problems with sizes that are considerably larger than those used in previous studies of mean field annealing. Dual mean field annealing is capable to find high quality solutions in running times that are orders of magnitude shorter than state of the art algorithms. Moreover, as may be expected for a mean field theory, the solutions tend to be more accurate as the number of variables grow.
The problem of pattern and scale in ecology: what have we learned in 20 years?
Chave, Jérôme
2013-05-01
Over the past 20 years, major advances have clarified how ecological patterns inform theory, and how in turn theory informs applied ecology. Also, there has been an increased recognition that the problem of scale at which ecological processes should be considered is critical if we are to produce general predictions. Ecological dynamics is always stochastic at small scales, but variability is conditional on the scale of description. The radical changes in the scope and aims of ecology over the past decades reflect in part the need to address pressing societal issues of environmental change. Technological advances in molecular biology, global positioning, sensing instrumentation and computational power should not be overlooked as an explanation for these radical changes. However, I argue that conceptual unification across ecology, genetics, evolution and physiology has fostered even more fertile questions. We are moving away from the view that evolution is played in a fixed ecological theatre: the theatre is being rapidly and relentlessly redesigned by the players themselves. The maintenance of ecosystem functions depends on shifts in species assemblages and on cellular metabolism, not only on flows of energy and matter. These findings have far reaching implications for our understanding of how ecosystem function and biodiversity will withstand (or not) environmental changes in the 21st century.
Validation of the Turkish Version of the Problem Areas in Diabetes Scale
Elisabeth M. J. Huis In ‘T Veld
2011-01-01
Full Text Available The Problem Areas in Diabetes (PAID scale is a widely used self-report measure that can facilitate detection of diabetes-specific emotional distress in clinical practice. The aim of this study was to assess the factor structure and validity of the Turkish version of the PAID. A validation study was conducted among 154 patients with insulin-naïve type 2 diabetes. Participants completed the PAID, Centre for Epidemiological Studies Depression Scale (CES-D, Insulin Treatment Appraisal Scale (ITAS, and World Health Organization-Five Well-Being Index (WHO-5 questionnaires. Exploratory factor analyses yielded a 2-factor structure, identifying a 15-item “diabetes distress” factor and a 5-item “support-related issues” factor. The total PAID-score and the two dimensions were associated with higher levels of depression and poor emotional well-being. In the present study, the Turkish version of the PAID had satisfactory psychometric properties, however, the factorial structure was found to differ from factor solutions from other countries.
无
2008-01-01
This paper is concerned with the resource allocation problem based on data envelopment analysis(DEA)which is generally found in practice such as in public services and in production process.In management context,the resource allocation has to achieve the effective-efficient-equality aim and tries to balance the different desires of two management layers:central manager and each sector.In mathematical programming context,to solve the resource allocation asks for introducing many optimization techniques such as multiple-objective programming and goal programming.We construct an algorithm framework by using comprehensive DEA tools including CCR,BCC models,inverse DEA model,the most compromising common weights analysis model,and extra resource allocation algorithm.Returns to scale characteristic is put major place for analyzing DMUs' scale economies and used to select DMU candidates before resource allocation.By combining extra resource allocation algorithm with scale economies target,we propose a resource allocation solution,which can achieve the effective-efficient-equality target and also provide information for future resource allocation.Many numerical examples are discussed in this paper,which also verify our work.
Edward M. Sosu
2017-09-01
Full Text Available This study investigated the mechanisms by which experiences of poverty influence the trajectory of conduct problems among preschool children. Drawing on two theoretical perspectives, we focused on family stress (stress and harsh discipline and investment variables (educational investment, nutrition, and cognitive ability as key mediators. Structural equation modeling techniques with prospective longitudinal data from the Growing Up in Scotland survey (N = 3,375 were used. Economic deprivation measured around the first birthday of the sample children had both direct and indirect effects on conduct problems across time (ages 4, 5, and 6. In line with the family stress hypothesis, higher levels of childhood poverty predicted conduct problems across time through increased parental stress and punitive discipline. Consistent with the investment model, childhood deprivation was associated with higher levels of conduct problems via educational investment and cognitive ability. The study extends previous knowledge on the mechanisms of this effect by demonstrating that cognitive ability is a key mediator between poverty and the trajectory of childhood conduct problems. This suggests that interventions aimed at reducing child conduct problems should be expanded to include factors that compromise parenting as well as improve child cognitive ability.
无
2010-01-01
By different fixed point theorems in cones, sufficient conditions for the existence and multiple existence of positive solutions to a class of second-order multi-point boundary value problem for dynamic equation on time scales are obtained.
Outcomes of Domestic Standard Problem-03 : Scaling Capability of Facility Data
Park, Yusun; Youn, Bumsu; Lee, Seung-won; Kim, Won-tae; Kang, Kyoung-ho; Choi, Ki-yong [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)
2015-10-15
The Domestic Standard Problem (DSP) previous two DSPs provided good research opportunities to many nuclear organizations to understand the capability of the current system-scale safety analysis codes and to find a way for further code development area. Thus, the third DSP program was launched in the 2nd half of the year 2012. As the third DSP exercise (DSP-03), a double-ended guillotine break of the main steam line at an 8% power without loss of off-site power (LOOP) was decided a target scenario. Seventeen domestic organizations joined this DSP exercise. This DSP exercise was performed in an open calculation environment similar to the previous ones. In the present DSP-03, taking into accounts the different levels of code experiences and expertise, three sub-topics were suggested by operating agency. Among them, the investigation on scaling capability of facility data which was the topic of Group A will be discussed in this paper. Agreed participants should perform two calculations with the ATLAS model and the APR1400 model. By comparing major and detailed local parameters from both calculation models, scaling capability of the facility data was investigated. The 38.6 mm MSLB in ATLAS test facility was calculated using SPACE and MARS-KS code. To analyze the effect of scaling on the system behavior, MSLB in APR-1400 was also simulated in this study and following results were obtained. - The code predicted appropriately the overall MSLB experimental data obtained from ATLAS test facility. - The break flow calculated by code was lower than that of experimental data. - And the difference between calculated value and measured value was attributed to the measurement of mass from break flow. - The temperatures of core inlet and outlet of ATLAS test facility were predicted lower than those of experimental data.
Miner, Adam S; Schueller, Stephen M; Lattie, Emily G; Mohr, David C
2015-12-30
The Cognitive and Behavioral Response to Stress Scale (CB-RSS) is a self-report measure of the use and helpfulness of several cognitive and behavioral skills. Unlike other measures that focus on language specific to terms used in therapy, the CB-RSS was intended to tap the strategies in ways that might be understandable to those who had not undergone therapy. The measure was included in a clinical trial of cognitive-behavioral therapy for depression and completed by 325 participants at baseline and end of treatment (18 weeks). Psychometric properties of the scale were assessed through iterative exploratory and confirmatory factor analyses. These analyses identified two subscales, cognitive and behavioral skills, each with high reliability. Validity was addressed by investigating relationships with depression symptoms, positive affect, perceived stress, and coping self-efficacy. End of treatment scores predicted changes in all outcomes, with the largest relationships between baseline CB-RSS scales and coping self-efficacy. These findings suggest that the CB-RSS is a useful tool to measure cognitive and behavioral skills both at baseline (prior to treatment) as well as during the course of treatment.
Reynolds stress scaling in pipe flow turbulence—first results from CICLoPE
Örlü, R.; Fiorini, T.; Segalini, A.; Bellani, G.; Talamelli, A.; Alfredsson, P. H.
2017-03-01
This paper reports the first turbulence measurements performed in the Long Pipe Facility at the Center for International Cooperation in Long Pipe Experiments (CICLoPE). In particular, the Reynolds stress components obtained from a number of straight and boundary-layer-type single-wire and X-wire probes up to a friction Reynolds number of 3.8×104 are reported. In agreement with turbulent boundary-layer experiments as well as with results from the Superpipe, the present measurements show a clear logarithmic region in the streamwise variance profile, with a Townsend-Perry constant of A2≈1.26. The wall-normal variance profile exhibits a Reynolds-number-independent plateau, while the spanwise component was found to obey a logarithmic scaling over a much wider wall-normal distance than the other two components, with a slope that is nearly half of that of the Townsend-Perry constant, i.e. A2,w≈A2/2. The present results therefore provide strong support for the scaling of the Reynolds stress tensor based on the attached-eddy hypothesis. Intriguingly, the wall-normal and spanwise components exhibit higher amplitudes than in previous studies, and therefore call for follow-up studies in CICLoPE, as well as other large-scale facilities.
Stress in Medical Students in a Problem-Based Learning Curriculum
Dagistani, Ahmad; Al Hejaili, Fawwaz; Binsalih, Salih; Al Jahdali, Hamdan; Al Sayyari, Abdulla
2016-01-01
Background: This study aims to assess stress level and its drivers among medical students using a PBL teaching system Method: Higher Education Stress Inventory (HESI,) was used to assess stress among medical students. All students in the College of Medicine were enrolled. Results: The response rate was 99%.The prevalence of stress was 54.7%. The…
Shek, Daniel T. L.
2003-01-01
Studied the association between perceived economic stress and adolescent adjustment in 229 Chinese adolescents using children and parent reports of economic stress. Findings show differences in perceived stress between parents and children. A lower level of perceived economic stress was generally related to better adolescent mental health and…
Poulios, Konstantinos; Niordson, Christian Frithiof
2016-01-01
The compressive strength of unidirectionally or layer-wise reinforced composite materials in direction parallel to their reinforcement is limited by micro-buckling instabilities. Although the inherent compressive strength of a given material micro-structure can easily be determined by assessing its...... compressive stress but also on spatial stress or strain gradients, rendering failure initiation size scale dependent. The present work demonstrates and investigates the aforementioned effect through numerical simulations of periodically layered structures withnotches and holes under bending and compressive...... loads, respectively. The presented results emphasize the importance of the reinforcing layer thickness on the load carrying capacity of the investigated structures, at a constant volumetric fraction of the reinforcement. The observed strengthening at higher values of the relative layer thickness...
Richmond, Katherine; Levant, Ronald; Smalley, Bryant; Cook, Stephen
2015-01-01
The purpose of this study was to conduct a confirmatory factor analytic investigation of the Femininity Ideology Scale (FIS) and to assess whether feminine gender role stress mediated the relationship between femininity ideology and anxiety. During the 2010-2011 academic year, a convenience sample of 606 college women were recruited from three universities and one college. Confirmatory factor analysis supported a four- versus the hypothesized five-factor model, resulting in the elimination of the Dependency/Deference factor. Mediation analysis using structural equation modeling indicated no direct relationship between Femininity Ideology and Anxiety, although an indirect one was observed, mediated through Feminine Gender Role Stress. The results are discussed in terms of possible changes in contemporary notions of femininity, and the utility of using the FIS in applied therapeutic settings.
Gross, Lutz; Altinay, Cihan; Fenwick, Joel; Smith, Troy
2014-05-01
inversion and appropriate solution schemes in escript. We will also give a brief introduction into escript's open framework for defining and solving geophysical inversion problems. Finally we will show some benchmark results to demonstrate the computational scalability of the inversion method across a large number of cores and compute nodes in a parallel computing environment. References: - L. Gross et al. (2013): Escript Solving Partial Differential Equations in Python Version 3.4, The University of Queensland, https://launchpad.net/escript-finley - L. Gross and C. Kemp (2013) Large Scale Joint Inversion of Geophysical Data using the Finite Element Method in escript. ASEG Extended Abstracts 2013, http://dx.doi.org/10.1071/ASEG2013ab306 - T. Poulet, L. Gross, D. Georgiev, J. Cleverley (2012): escript-RT: Reactive transport simulation in Python using escript, Computers & Geosciences, Volume 45, 168-176. http://dx.doi.org/10.1016/j.cageo.2011.11.005.
Khan, Aqeel; Hamdan, Abdul Rahim; Ahmad, Roslee; Mustaffa, Mohamed Sharif; Mahalle, Salwa
2016-02-01
This study examined whether productive coping styles and social support were significant mediators of the relationship between academic stress and suicidal ideation. The survey was performed on a sample of 300 Malaysian and 300 Indian college students. The participants completed psychological assessments of productive coping styles, social support, academic stress, and suicidal ideation. Significant cultural and demographic differences emerged. Indian students reported higher suicidal ideation and academic stress than did Malaysian students, and Malaysian students received more social support and had better problem-solving coping styles than did Indian students. Overall, students who were male, non-religious, and from low-income families reported more academic stress and more suicidal ideation. Productive coping styles and overall social support strongly affected the relationship between academic stress and suicidal ideation among both countries' participants.
Solution matching for a three-point boundary-value problem on atime scale
Martin Eggensperger
2004-07-01
Full Text Available Let $mathbb{T}$ be a time scale such that $t_1, t_2, t_3 in mathbb{T}$. We show the existence of a unique solution for the three-point boundary value problem $$displaylines{ y^{DeltaDeltaDelta}(t = f(t, y(t, y^Delta(t, y^{DeltaDelta}(t, quad t in [t_1, t_3] cap mathbb{T},cr y(t_1 = y_1, quad y(t_2 = y_2, quad y(t_3 = y_3,. }$$ We do this by matching a solution to the first equation satisfying a two-point boundary conditions on $[t_1, t_2] cap mathbb{T}$ with a solution satisfying a two-point boundary conditions on $[t_2, t_3] cap mathbb{T}$.
Application of spectral Lanczos decomposition method to large scale problems arising geophysics
Tamarchenko, T. [Western Atlas Logging Services, Houston, TX (United States)
1996-12-31
This paper presents an application of Spectral Lanczos Decomposition Method (SLDM) to numerical modeling of electromagnetic diffusion and elastic waves propagation in inhomogeneous media. SLDM approximates an action of a matrix function as a linear combination of basis vectors in Krylov subspace. I applied the method to model electromagnetic fields in three-dimensions and elastic waves in two dimensions. The finite-difference approximation of the spatial part of differential operator reduces the initial boundary-value problem to a system of ordinary differential equations with respect to time. The solution to this system requires calculating exponential and sine/cosine functions of the stiffness matrices. Large scale numerical examples are in a good agreement with the theoretical error bounds and stability estimates given by Druskin, Knizhnerman, 1987.
Schrauwen, Jelle T C; Schwarz, Janina C V; Wentzel, Jolanda J; van der Steen, Antonius F W; Siebes, Maria; Gijsen, Frank J H
2016-05-15
The aim of this study was to determine if reliable patient-specific wall shear stress (WSS) can be computed when diameter-based scaling laws are used to impose the boundary conditions for computational fluid dynamics. This study focused on mildly diseased human coronary bifurcations since they are predilection sites for atherosclerosis. Eight patients scheduled for percutaneous coronary intervention were imaged with angiography. The velocity proximal and distal of a bifurcation was acquired with intravascular Doppler measurements. These measurements were used for inflow and outflow boundary conditions for the first set of WSS computations. For the second set of computations, absolute inflow and outflow ratios were derived from geometry-based scaling laws based on angiography data. Normalized WSS maps per segment were obtained by dividing the absolute WSS by the mean WSS value. Absolute and normalized WSS maps from the measured-approach and the scaled-approach were compared. A reasonable agreement was found between the measured and scaled inflows, with a median difference of 0.08 ml/s [-0.01; 0.20]. The measured and the scaled outflow ratios showed a good agreement: 1.5 percentage points [-19.0; 4.5]. Absolute WSS maps were sensitive to the inflow and outflow variations, and relatively large differences between the two approaches were observed. For normalized WSS maps, the results for the two approaches were equivalent. This study showed that normalized WSS can be obtained from angiography data alone by applying diameter-based scaling laws to define the boundary conditions. Caution should be taken when absolute WSS is assessed from computations using scaled boundary conditions.
Efstratiadis, Andreas; Tsoukalas, Ioannis; Kossieris, Panayiotis; Karavokiros, George; Christofides, Antonis; Siskos, Alexandros; Mamassis, Nikos; Koutsoyiannis, Demetris
2015-04-01
Modelling of large-scale hybrid renewable energy systems (HRES) is a challenging task, for which several open computational issues exist. HRES comprise typical components of hydrosystems (reservoirs, boreholes, conveyance networks, hydropower stations, pumps, water demand nodes, etc.), which are dynamically linked with renewables (e.g., wind turbines, solar parks) and energy demand nodes. In such systems, apart from the well-known shortcomings of water resources modelling (nonlinear dynamics, unknown future inflows, large number of variables and constraints, conflicting criteria, etc.), additional complexities and uncertainties arise due to the introduction of energy components and associated fluxes. A major difficulty is the need for coupling two different temporal scales, given that in hydrosystem modeling, monthly simulation steps are typically adopted, yet for a faithful representation of the energy balance (i.e. energy production vs. demand) a much finer resolution (e.g. hourly) is required. Another drawback is the increase of control variables, constraints and objectives, due to the simultaneous modelling of the two parallel fluxes (i.e. water and energy) and their interactions. Finally, since the driving hydrometeorological processes of the integrated system are inherently uncertain, it is often essential to use synthetically generated input time series of large length, in order to assess the system performance in terms of reliability and risk, with satisfactory accuracy. To address these issues, we propose an effective and efficient modeling framework, key objectives of which are: (a) the substantial reduction of control variables, through parsimonious yet consistent parameterizations; (b) the substantial decrease of computational burden of simulation, by linearizing the combined water and energy allocation problem of each individual time step, and solve each local sub-problem through very fast linear network programming algorithms, and (c) the substantial
Ovington, Linda A.; Saliba, Anthony J.; Goldring, Jeremy
2016-01-01
This article reports the development of a brief self-report measure of dispositional insight problem solving, the Dispositional Insight Scale (DIS). From a representative Australian database, 1,069 adults (536 women and 533 men) completed an online questionnaire. An exploratory and confirmatory factor analysis revealed a 5-item scale, with all…
Bai, Jieru
2016-04-01
Chinese students are the biggest ethnic group of international students in the United States. This study aims to develop a reliable and valid scale to accurately measure their acculturative stress. A 72-item pool was sent online to Chinese students and a five-factor scale of 32 items was generated by exploratory factor analysis. The five factors included language insufficiency, social isolation, perceived discrimination, academic pressure, and guilt toward family. The Acculturative Stress Scale for Chinese Students demonstrated high reliability and initial validity by predicting depression and life satisfaction. It was the first Chinese scale of acculturative stress developed and validated among a Chinese student sample in the United States. In the future, the scale can be used as a diagnostic tool by mental health professionals and a self-assessment tool by Chinese students. (c) 2016 APA, all rights reserved.
Solving the problem of imaging resolution: stochastic multi-scale image fusion
Karsanina, Marina; Mallants, Dirk; Gilyazetdinova, Dina; Gerke, Kiril
2016-04-01
Structural features of porous materials define the majority of its physical properties, including water infiltration and redistribution, multi-phase flow (e.g. simultaneous water/air flow, gas exchange between biologically active soil root zone and atmosphere, etc.) and solute transport. To characterize soil and rock microstructure X-ray microtomography is extremely useful. However, as any other imaging technique, this one also has a significant drawback - a trade-off between sample size and resolution. The latter is a significant problem for multi-scale complex structures, especially such as soils and carbonates. Other imaging techniques, for example, SEM/FIB-SEM or X-ray macrotomography can be helpful in obtaining higher resolution or wider field of view. The ultimate goal is to create a single dataset containing information from all scales or to characterize such multi-scale structure. In this contribution we demonstrate a general solution for merging multiscale categorical spatial data into a single dataset using stochastic reconstructions with rescaled correlation functions. The versatility of the method is demonstrated by merging three images representing macro, micro and nanoscale spatial information on porous media structure. Images obtained by X-ray microtomography and scanning electron microscopy were fused into a single image with predefined resolution. The methodology is sufficiently generic for implementation of other stochastic reconstruction techniques, any number of scales, any number of material phases, and any number of images for a given scale. The methodology can be further used to assess effective properties of fused porous media images or to compress voluminous spatial datasets for efficient data storage. Potential practical applications of this method are abundant in soil science, hydrology and petroleum engineering, as well as other geosciences. This work was partially supported by RSF grant 14-17-00658 (X-ray microtomography study of shale
Pore-scale modeling of moving contact line problems in immiscible two-phase flow
Kucala, Alec; Noble, David; Martinez, Mario
2016-11-01
Accurate modeling of moving contact line (MCL) problems is imperative in predicting capillary pressure vs. saturation curves, permeability, and preferential flow paths for a variety of applications, including geological carbon storage (GCS) and enhanced oil recovery (EOR). Here, we present a model for the moving contact line using pore-scale computational fluid dynamics (CFD) which solves the full, time-dependent Navier-Stokes equations using the Galerkin finite-element method. The MCL is modeled as a surface traction force proportional to the surface tension, dependent on the static properties of the immiscible fluid/solid system. We present a variety of verification test cases for simple two- and three-dimensional geometries to validate the current model, including threshold pressure predictions in flows through pore-throats for a variety of wetting angles. Simulations involving more complex geometries are also presented to be used in future simulations for GCS and EOR problems. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.
María-Teresa Sebastiá-Frasquet
2014-03-01
Full Text Available The policies that define the use and management of wetlands in Spain have undergone tremendous changes in recent decades. During the period of 1950–1980, Land Reform Plans promoted filling and draining of these areas for agricultural use. In 1986, with the incorporation of Spain to the European Union (EU, there was a sudden change of direction in these policies, which, thereafter, pursued restoring and protecting these ecosystems. This change, combined with increasing urban development and infrastructure pressures (e.g., roads, golf courses, etc., creates a conflict of uses which complicates the management of these ecosystems by local governments. This study analyzes the effectiveness of policies and management tools of important coastal wetlands at the local scale in the Valencian Community (Western Mediterranean Sea using a strengths-weaknesses-opportunities-threats (SWOT methodology. A supra-municipal model of environmental planning is proposed to enable consistent management at a regional scale. This model enhances local government’s effectiveness and it can be applied in other areas with similar problems.
Handy, C R; Okbagabir, S; Yarahmad, T
2003-01-01
For one-dimensional Schroedinger quantum systems, the correlation expression S(x, tau, a) ident to PSI*(x - tau/2/a)PSI(x + tau/2) satisfies a fourth-order linear differential equation with regard to x. This generalizes the result previously derived by Handy (2001 J. Phys. A: Math. Gen. 34 L271), and Handy and Wang (2001 J. Phys. A: Math. Gen. 34 8297), with regard to S(x, 0, 1). We are then able to incorporate this within a generalized Wigner transform representation, through the use of scalets (Handy C R and Brooks H A 2001 J. Phys. A: Math. Gen. 34 3577). Energy quantization is achieved through a moment problem positivity analysis (focusing on the moments of the probability density, vertical bar PSI vertical bar sup 2) at a=1, tau=0. The wavefunction, PSI, is then generated through a multiscale analysis proceeding from the unity scale, extended into the zero scale limit. The power moments, mu sub p =integral dx x sup p PSI(x), can be generated through a similar procedure. We present the general formalism a...
Harnessing Petaflop-Scale Multi-Core Supercomputing for Problems in Space Science
Albright, B. J.; Yin, L.; Bowers, K. J.; Daughton, W.; Bergen, B.; Kwan, T. J.
2008-12-01
The particle-in-cell kinetic plasma code VPIC has been migrated successfully to the world's fastest supercomputer, Roadrunner, a hybrid multi-core platform built by IBM for the Los Alamos National Laboratory. How this was achieved will be described and examples of state-of-the-art calculations in space science, in particular, the study of magnetic reconnection, will be presented. With VPIC on Roadrunner, we have performed, for the first time, plasma PIC calculations with over one trillion particles, >100× larger than calculations considered "heroic" by community standards. This allows examination of physics at unprecedented scale and fidelity. Roadrunner is an example of an emerging paradigm in supercomputing: the trend toward multi-core systems with deep hierarchies and where memory bandwidth optimization is vital to achieving high performance. Getting VPIC to perform well on such systems is a formidable challenge: the core algorithm is memory bandwidth limited with low compute-to-data ratio and requires random access to memory in its inner loop. That we were able to get VPIC to perform and scale well, achieving >0.374 Pflop/s and linear weak scaling on real physics problems on up to the full 12240-core Roadrunner machine, bodes well for harnessing these machines for our community's needs in the future. Many of the design considerations encountered commute to other multi-core and accelerated (e.g., via GPU) platforms and we modified VPIC with flexibility in mind. These will be summarized and strategies for how one might adapt a code for such platforms will be shared. Work performed under the auspices of the U.S. DOE by the LANS LLC Los Alamos National Laboratory. Dr. Bowers is a LANL Guest Scientist; he is presently at D. E. Shaw Research LLC, 120 W 45th Street, 39th Floor, New York, NY 10036.
João Luís Alves Apóstolo; Aida Cruz Mendes; Zaida Aguiar Azeredo
2006-01-01
Objective: to adapt to Portuguese, of Portugal, the Depression, Anxiety and Stress Scales, a 21-item short scale (DASS 21), designed to measure depression, anxiety and stress. Method: After translation and back-translation with the help of experts, the DASS 21 was administered to patients in external psychiatry consults (N=101), and its internal consistency, construct validity and concurrent validity were measured. Results: The DASS 21 properties certify its quality to measure emotional state...
Calculation of Growth Stress in SiO2 Scales Formed by Oxidation of SiC Fibers (PREPRINT)
2012-07-01
Kinetics of High - Purity Silicon Carbide from 800 to 1100 C. J. Am. Ceram. Soc. 79, 2897-2911 (1996). 45 Ogbuji, U. J. T. & Opila, E. J. A Comparison...to SiO2 generates very large growth stresses. Microstructural evidence for these stresses exists for crystalline scales on SiC fibers. High ...dislocation densities in crystalline SiO2 near the SiC -SiO2 interface suggest high shear stresses exist during growth of new crystalline scale.1 Axial cracks
Canonical Modeling of the Multi-Scale Regulation of the Heat Stress Response in Yeast
Luis L. Fonseca
2012-02-01
Full Text Available Heat is one of the most fundamental and ancient environmental stresses, and response mechanisms are found in prokaryotes and shared among most eukaryotes. In the budding yeast Saccharomyces cerevisiae, the heat stress response involves coordinated changes at all biological levels, from gene expression to protein and metabolite abundances, and to temporary adjustments in physiology. Due to its integrative multi-level-multi-scale nature, heat adaptation constitutes a complex dynamic process, which has forced most experimental and modeling analyses in the past to focus on just one or a few of its aspects. Here we review the basic components of the heat stress response in yeast and outline what has been done, and what needs to be done, to merge the available information into computational structures that permit comprehensive diagnostics, interrogation, and interpretation. We illustrate the process in particular with the coordination of two metabolic responses, namely the dramatic accumulation of the protective disaccharide trehalose and the substantial change in the profile of sphingolipids, which in turn affect gene expression. The proposed methods primarily use differential equations in the canonical modeling framework of Biochemical Systems Theory (BST, which permits the relatively easy construction of coarse, initial models even in systems that are incompletely characterized.
Psychometric properties of the Chinese version of the Perceived Stress Scale in policewomen.
Zhen Wang
Full Text Available BACKGROUND: The 10-item Perceived Stress Scale (PSS-10 is one of most widely used instruments to measure a global level of perceived stress in a range of clinical and research settings. This study was conducted to examine the psychometric properties of the Simplified Chinese version of the PSS-10 in policewomen. METHODOLOGY: A total of 240 policewomen were recruited in this study. The Simplified Chinese versions of the PSS-10, the Beck Depression Inventory Revised (BDI-II, and the Beck Anxiety Inventory (BAI were administered to all participants, and 36 of the participants were re-tested two weeks after the initial testing. PRINCIPAL FINDINGS: The overall Cronbach's alpha was 0.86, and the test-retest reliability coefficient was 0.68. Exploratory Factor Analysis (EFA yielded 2 factors with eigenvalues of 4.76 and 1.48, accounting for 62.41% of variance. Factor 1 consisted of 6 items representing "negative feelings"; whereas Factor 2 consisted of 4 items representing "positive feelings". The item loadings ranged from 0.72 to 0.83. The Confirmatory factor analysis (CFA indicated a very good fit of this two-factor model to this sample. The PSS-10 significantly correlated with both BDI-II and BAI, indicating an acceptable concurrent validity. CONCLUSIONS: The Simplified Chinese version of the PSS-10 demonstrated adequate psychometric properties for evaluating stress levels. The results support its use among the Chinese population.
Ouellet-Morin, Isabelle; Odgers, Candice L.; Danese, Andrea; Bowes, Lucy; Shakoor, Sania; Papadopoulos, Andrew S.; Caspi, Avshalom; Moffitt, Terrie E.; Arseneault, Louise
2013-01-01
Background Evidence from animal and human studies suggests that early-life stress such as physical maltreatment has long-lasting effects on the hypothalamic-pituitary-adrenal (HPA) axis and is associated with blunted HPA axis reactivity in adulthood. Few studies have investigated whether blunted HPA axis reactivity observed in children exposed to early-life stress signals social, emotional, and behavioral problems. Methods Participants were 190 12-year-old children (50.5% males) recruited from the Environmental Risk Longitudinal Twin Study, a nationally representative 1994 to 1995 cohort of families with twins. Cortisol responses to psychosocial stress were measured in maltreated/ bullied (n = 64) and comparison children (n = 126). We ascertained maltreatment and bullying victimization using mothers’ reports and assessed children’s social, emotional, and behavioral problems at ages 5 and 12 using mothers’ and teachers’ reports. Results Piecewise multilevel growth curve analyses indicated that maltreated/bullied and comparison children showed distinct cortisol responses to stress. Specifically, maltreated/bullied children had lower cortisol responses than comparison children who exhibited a significant increase. Lower cortisol responses were, in turn, associated with more social and behavioral problems among maltreated/bullied children. Conclusions These findings provide support for the influence of childhood harm on blunted HPAaxis reactivity and its potential impacton children’s functioning. Our findings emphasize the need to integrate stress biomarkers in guiding prevention efforts for young victims. PMID:21839988
Nordin, Maria; Nordin, Steven
2013-12-01
The perceived stress scale (PSS) has been translated to several languages and validated in many cultures. The longer 14-item version (PSS-14), has been translated to Swedish and validated for Swedish use. However, the Swedish version of the shorter 10-item version (PSS-10) has not been validated before. Therefore, the aim of this study was to evaluate the Swedish version of the PSS-10 with regard to reliability and validity, and to provide normative data. Data from 3,406 individuals who took part in the Västerbotten Environmental Health Study in Sweden were used. The respondents constitute a random sample, aged 18 to 79 years, and stratified for age and sex. They responded to the Swedish version of the PSS-10 as well as to the hospital anxiety and depression scale, and the Shirom Melamed burnout questionnaire for assessment of construct validity. The results show that the PSS-10 provides approximately normally distributed data, has good internal reliability (Cronbach's alpha 0.84), and has good construct validity with anxiety (r = 0.68), depression (r = 0.57), and mental/physical exhaustion (r = 0.71). The favorable psychometric properties of the Swedish version of the PSS-10 suggest use of the instrument for assessing perceived stress in Swedish and similar populations. © 2013 The Scandinavian Psychological Associations.
Rutland, J Brian; Sheets, Tilman; Young, Tony
2007-12-01
This exploratory study examines a subset of mobile phone use, the compulsive use of short message service (SMS) text messaging. A measure of SMS use, the SMS Problem Use Diagnostic Questionnaire (SMS-PUDQ), was developed and found to possess acceptable reliability and validity when compared to other measures such as self-reports of time spent using SMS and scores on a survey of problem mobile phone use. Implications for the field of addiction research, technological and behavioral addictions in particular, are discussed, and directions for future research are suggested.
EXPLORING PHYSICIANS' DISSATISFACTION AND WORK-RELATED STRESS: DEVELOPMENT OF THE PhyDis SCALE
Monica Pedrazza
2016-08-01
Full Text Available Research, all over the world, is starting to recognize the potential impact of physicians’ dissatisfaction and burnout on their productivity, that is, on their intent to leave the job, on their work ability, on the amount of sick leave days, on their intent to continue practicing, and last but not least, on the quality of the services provided, which is an essential part of the general medical care system. It was interest of the provincial medical board’s ethical committee to acquire information about physician’s work-related stress and dissatisfaction. The research group was committed to define the indicators of dissatisfaction and work-related stressors. Focus groups were carried out, 21 stressful experience’s indicators were identified; we developed an online questionnaire to assess the amount of perceived stress relating to each indicator at work (3070 physicians were contacted by e-mail; quantitative and qualitative data analysis were carried out. The grounded theory perspective was applied in order to assure the most reliable procedure to investigate the concepts’ structure of work-related stress. We tested the five dimensions' model of the stressful experience with a confirmatory factor analysis: Personal Costs; Decline in Public Image and Role Uncertainty; Physician's Responsibility toward hopelessly ill Patients; Relationship with Staff and Colleagues; Bureaucracy. We split the sample according to attachment style (secure and insecure -anxious and avoidant-. Results show the complex representation of physicians’ dissatisfaction at work also with references to the variable of individual difference of attachment security/insecurity. The discriminant validity of the scale was tested. The original contribution of this paper lies on the one hand in the qualitative in depth inductive analysis of physicians’ dissatisfaction starting from physicians’ perception, on the other hand, it represents the first attempt to analyze the
Coluccia, Anna; Lorini, Francesca; Ferretti, Fabio; Pozza, Andrea; Gaetani, Marco
2015-01-01
The issue of the assessment of work-related stress has stimulated in recent years, the production of several theoretical paradigms and assessment tools. In this paper we present a new scale for the assessment of organizational well-being and work-related stress specific for healthcare organizations (Work-related Stress Assessment Scale - WSAS). The goal of the authors is to examine the psychometric properties of the scale, so that it can be used in the healthcare setting as a work-related stress assessment tool. The answers of 230 healthcare professionals belonging to different roles have been analyzed. The study was realized in 16 Units of the University Hospital "S. Maria alle Scotte "of Siena. The exploratory factor analysis (EFA) revealed the presence of five factors with good internal consistency and reliability, "relationship to the structure of proximity" (α = 0.93) "change" (α = 0.92), "organization of work "(α = 0.81)," relationship with the company / Governance "(α = 0.87)" working environment "(α = 0.83). The analysis of SEM (Structural Equation Models) has confirmed the goodness of the factor solution (NNFI = 0.835, CFI = 0.921, RMSEA = 0.060). The good psychometric qualities, the shortness and simplicity of the scale WSAS makes it a useful aid in the assessment of work-related stress in health care organizations.
Shek, Daniel T. L.
2005-01-01
The relationships between perceived economic stress (current economic hardship and future economic worry) and emotional quality of life (existential well-being, life satisfaction, self-esteem, sense of mastery, psychological morbidity) as well as problem behavior (substance abuse and delinquency) were examined in 1519 Chinese adolescents with and…
Davis, Allyson L.; Neece, Cameron L.
2017-01-01
Introduction: Studies have shown that parents of children with pervasive developmental disorders (PDD) exhibit higher levels of stress than parents of typically developing children or children with other types of developmental delays (DD). This relationship appears to be mediated by elevated levels of behavior problems observed in children with…
Shawler, Paul M.; Sullivan, Maureen A.
2017-01-01
The current study investigated the parent-child relationship by examining associations between parent stress, parental discipline strategies, child disruptive behavior problems, and level of autism spectrum disorder (ASD) symptoms. A sample of 130 parents of children with ASD ages 3 to 11 years participated. Parents reported high levels of parent…
Arslan, Coskun
2010-01-01
The purpose of this study was to investigate the anger and anger expression styles with respect to coping with stress and interpersonal problem-solving. The participants were 468 (258 female and 210 male, between 17-30 years old) university students. Pearson product-moment correlation coefficients and multiple hierarchical regression analysis were…
Nygaard, Egil; Jensen, Tine K.; Dyb, Grete
2012-01-01
The aim of this study was to evaluate the structure of posttraumatic stress reaction factors and their relation to general mental health problems in Norwegian children exposed to the tsunami on December 26, 2004. A total of 133 children and adolescents (ages 6-17) were interviewed 10 months posttsunami using the UCLA PTSD Reaction Index, and 104…
Shek, Daniel T. L.
2005-01-01
The relationships between perceived economic stress (current economic hardship and future economic worry) and emotional quality of life (existential well-being, life satisfaction, self-esteem, sense of mastery, psychological morbidity) as well as problem behavior (substance abuse and delinquency) were examined in 1519 Chinese adolescents with and…
Laue-DIC: a new method for improved stress field measurements at the micrometer scale
Petit, J., E-mail: johannpetit@u-paris10.fr [LEME, Université Paris Ouest, 50 rue de Sèvres, F-92410 Ville d’Avray (France); Castelnau, O. [PIMM, CNRS, Arts and Métiers ParisTech, 151 Bd de l’Hopital, F-75013 Paris (France); Bornert, M. [Laboratoire Navier, Université Paris-Est, École des Ponts ParisTech, F-77455 Marne-la-Vallée (France); Zhang, F. G. [PIMM, CNRS, Arts and Métiers ParisTech, 151 Bd de l’Hopital, F-75013 Paris (France); Hofmann, F.; Korsunsky, A. M. [Department of Engineering Science, University of Oxford, Parks Road, Oxford OX1 3PJ (United Kingdom); Faurie, D. [LSPM, CNRS, Université Paris 13, 93430 Villetaneuse (France); Le Bourlot, C. [INSA-Lyon, MATEIS CNRS UMR5510, F-69621 Villeurbanne (France); Micha, J. S. [Université Grenoble Alpes, INAC-SPrAM, F-38000 Grenoble (France); CNRS, SPrAM, F-38000 Grenoble (France); CRG-IF BM32 at ESRF, 71 Avenue des Martyrs, F-38000 Grenoble (France); Robach, O.; Ulrich, O. [Université Grenoble Alpes, INAC-SPrAM, F-38000 Grenoble (France); CRG-IF BM32 at ESRF, 71 Avenue des Martyrs, F-38000 Grenoble (France); CEA, INAC-SP2M, F-38000 Grenoble (France)
2015-05-09
The increment of elastic strain distribution, with a micrometer spatial resolution, is obtained by the correlation of successive Laue images. Application to a bent Si crystal allows evaluation of the accuracy of this new Laue-DIC method, which is about 10{sup −5}. A better understanding of the effective mechanical behavior of polycrystalline materials requires an accurate knowledge of the behavior at a scale smaller than the grain size. The X-ray Laue microdiffraction technique available at beamline BM32 at the European Synchrotron Radiation Facility is ideally suited for probing elastic strains (and associated stresses) in deformed polycrystalline materials with a spatial resolution smaller than a micrometer. However, the standard technique used to evaluate local stresses from the distortion of Laue patterns lacks accuracy for many micromechanical applications, mostly due to (i) the fitting of Laue spots by analytical functions, and (ii) the necessary comparison of the measured pattern with the theoretical one from an unstrained reference specimen. In the present paper, a new method for the analysis of Laue images is presented. A Digital Image Correlation (DIC) technique, which is essentially insensitive to the shape of Laue spots, is applied to measure the relative distortion of Laue patterns acquired at two different positions on the specimen. The new method is tested on an in situ deformed Si single-crystal, for which the prescribed stress distribution has been calculated by finite-element analysis. It is shown that the new Laue-DIC method allows determination of local stresses with a strain resolution of the order of 10{sup −5}.
Shivendra Jena
2015-01-01
Full Text Available Background: Incidence of stress among medical students has been reported to be between high and very high. Medical students in pre-clinical phase are more likely to develop psychological distress than medical students in clinical phase. It may affect academic performance and lead to anxiety, depression and substance abuse. Methods: First year students of one government medical college and one private medical college of Kanpur, Uttar Pradesh, India, were surveyed to find out stress and mental health problems shortly after their admission. Results: The two colleges showed difference in the frequencies of a number of factors- current stress, sleep problem, sad mood, both parents working, parents giving sufficient time, non-participation in extra-curricular activities, sharing problem with their families, having break-up in a romantic relationship and poor relationships with classmates and roommate. More students of the government medical college reported to have current stress compared to the students of the private medical college. While all students of the government medical who had stress since admission did not recover from it, 55.56% of students of the private medical college recovered from it at the time of our survey. Conclusion: a Psychiatry Department of every medical college should be involved in screening 1st year students having stress and mental health problems and managing them. b Medical education should be imparted in more relaxed and fun filled manner to help students cope with the long and difficult course. [Int J Res Med Sci 2015; 3(1.000: 130-134
Reynolds stress scaling in pipe flow turbulence-first results from CICLoPE.
Örlü, R; Fiorini, T; Segalini, A; Bellani, G; Talamelli, A; Alfredsson, P H
2017-03-13
This paper reports the first turbulence measurements performed in the Long Pipe Facility at the Center for International Cooperation in Long Pipe Experiments (CICLoPE). In particular, the Reynolds stress components obtained from a number of straight and boundary-layer-type single-wire and X-wire probes up to a friction Reynolds number of 3.8×10(4) are reported. In agreement with turbulent boundary-layer experiments as well as with results from the Superpipe, the present measurements show a clear logarithmic region in the streamwise variance profile, with a Townsend-Perry constant of A2≈1.26. The wall-normal variance profile exhibits a Reynolds-number-independent plateau, while the spanwise component was found to obey a logarithmic scaling over a much wider wall-normal distance than the other two components, with a slope that is nearly half of that of the Townsend-Perry constant, i.e. A2,w≈A2/2. The present results therefore provide strong support for the scaling of the Reynolds stress tensor based on the attached-eddy hypothesis. Intriguingly, the wall-normal and spanwise components exhibit higher amplitudes than in previous studies, and therefore call for follow-up studies in CICLoPE, as well as other large-scale facilities.This article is part of the themed issue 'Toward the development of high-fidelity models of wall turbulence at large Reynolds number'. © 2017 The Author(s).
A randomized Mirror-Prox method for solving structured large-scale matrix saddle-point problems
Baes, Michel; Nemirovski, Arkadi
2011-01-01
In this paper, we derive a randomized version of the Mirror-Prox method for solving some structured matrix saddle-point problems, such as the maximal eigenvalue minimization problem. Deterministic first-order schemes, such as Nesterov's Smoothing Techniques or standard Mirror-Prox methods, require the exact computation of a matrix exponential at every iteration, limiting the size of the problems they can solve. Our method allows us to use stochastic approximations of matrix exponentials. We prove that our randomized scheme decreases significantly the complexity of its deterministic counterpart for large-scale matrix saddle-point problems. Numerical experiments illustrate and confirm our theoretical results.
Impact of atomic-scale surface morphology on the size-dependent yield stress of gold nanoparticles
Yang, Liang; Bian, Jian-Jun; Wang, Gang-Feng
2017-06-01
Size-dependent mechanical properties have been revealed for nanowires, nanopillars and nanoparticles. On the surfaces of these nanosized elements, discrete atomic-scale steps will be naturally generated, however their impact on the mechanical properties and deformation has seldom been a concern. In this paper, large-scale molecular dynamics simulations are conducted to calculate the yield stress of gold nanoparticles under compression. In addition to absolute particle size, atomic-scale surface morphology induces significant fluctuation of the yield stress. An analytical relation is advanced to predict the yield stress of nanoparticles accounting for the influence of both size and surface morphology, which agrees well with atomic simulations. This study illuminates an important mechanism in nanosized elements, atomic-scale surface steps.
Abhishek Shukla
2016-12-01
Full Text Available This study aimed to investigate the reliability and validity of a new version of job stress scale, which measures the extended set of psychosocial stressors by adding new scales to the current version of the job stress scale. Additional scales were extensively collected from theoretical job stress models and similar questionnaire from different countries. Items were tested in workplace and refined through a pilot survey (n = 400 to examine the reliability and construct validity. Most scales showed acceptable levels of internal consistency, intra-class reliability, and test–retest reliability. Factor analysis and correlation analysis showed that these scales fit the theoretical expectations. These findings provided enough evidences that the new job stress scale is reliable and valid. Although confirmatory analysis should be examined in future studies. The new job stress scale is a useful instrument for organization and academicians to evaluate job stress in modern Indian workplace.
Schmengler, A. C.; Vlek, P. L. G.
2012-04-01
Modelling soil erosion requires a holistic understanding of the sediment dynamics in a complex environment. As most erosion models are scale-dependent and their parameterization is spatially limited, their application often requires special care, particularly in data-scarce environments. This study presents a hierarchical approach to overcome the limitations of a single model by using various quantitative methods and soil erosion models to cope with the issues of scale. At hillslope scale, the physically-based Water Erosion Prediction Project (WEPP)-model is used to simulate soil loss and deposition processes. Model simulations of soil loss vary between 5 to 50 t ha-1 yr-1 dependent on the spatial location on the hillslope and have only limited correspondence with the results of the 137Cs technique. These differences in absolute soil loss values could be either due to internal shortcomings of each approach or to external scale-related uncertainties. Pedo-geomorphological soil investigations along a catena confirm that estimations by the 137Cs technique are more appropriate in reflecting both the spatial extent and magnitude of soil erosion at hillslope scale. In order to account for sediment dynamics at a larger scale, the spatially-distributed WaTEM/SEDEM model is used to simulate soil erosion at catchment scale and to predict sediment delivery rates into a small water reservoir. Predicted sediment yield rates are compared with results gained from a bathymetric survey and sediment core analysis. Results show that specific sediment rates of 0.6 t ha-1 yr-1 by the model are in close agreement with observed sediment yield calculated from stratigraphical changes and downcore variations in 137Cs concentrations. Sediment erosion rates averaged over the entire catchment of 1 to 2 t ha-1 yr-1 are significantly lower than results obtained at hillslope scale confirming an inverse correlation between the magnitude of erosion rates and the spatial scale of the model. The
Gloster, Andrew T; Rhoades, Howard M; Novy, Diane; Klotsche, Jens; Senior, Ashley; Kunik, Mark; Wilson, Nancy; Stanley, Melinda A
2008-10-01
The Depression Anxiety Stress Scale (DASS) was designed to efficiently measure the core symptoms of anxiety and depression and has demonstrated positive psychometric properties in adult samples of anxiety and depression patients and student samples. Despite these findings, the psychometric properties of the DASS remain untested in older adults, for whom the identification of efficient measures of these constructs is especially important. To determine the psychometric properties of the DASS 21-item version in older adults, we analyzed data from 222 medical patients seeking treatment to manage worry. Consistent with younger samples, a three-factor structure best fit the data. Results also indicated good internal consistency, excellent convergent validity, and good discriminative validity, especially for the Depression scale. Receiver operating curve analyses indicated that the DASS-21 predicted the diagnostic presence of generalized anxiety disorder and depression as well as other commonly used measures. These data suggest that the DASS may be used with older adults in lieu of multiple scales designed to measure similar constructs, thereby reducing participant burden and facilitating assessment in settings with limited assessment resources.
Khadija Qamar
2014-10-01
Full Text Available The aim of this study was to determine the stress level of medical students and the relationship between stress and academic year. A cross-sectional, descriptive study was conducted at an undergraduate medical school with a five-year curriculum, in Pakistan, from January 2014 to April 2014. Medical students in the first four years were included in the study. The Kessler Psychological Distress Scale (K10, a self-administered questionnaire, was distributed to the students. A total of 445 medical students completed the questionnaire. The average stress score was 19.61 (SD = 6.76 with a range from 10 to 43. Stress was experienced by 169 students (41.7%. The scores of female students were higher than scores of males, indicating a higher stress level (P = 0.011. The relationship between stress and academic year was insignificant (P = 0.392.
Solutions to a combined problem of excessive hydrogen sulfide in biogas and struvite scaling.
Charles, W; Cord-Ruwisch, R; Ho, G; Costa, M; Spencer, P
2006-01-01
The Woodman Point Wastewater Treatment Plant (WWTP) in Western Australia has experienced two separate problems causing avoidable maintenance costs: the build-up of massive struvite (MgNH4PO4. 6H2O) scaling downstream of the anaerobic digester and the formation of hydrogen sulfide (H2S) levels in the digester gas to levels that compromised gas engine operation and caused high operating costs on the gas scrubber. As both problems hang together with a chemical imbalance in the anaerobic digester, we decided to investigate whether both problems could be (feasibly and economically) addressed by a common solution (such as dosing of iron solutions to precipitate both sulfide and phosphate), or by using separate approaches. Laboratory results showed that, the hydrogen sulfide emission in digesters could be effectively and economically controlled by the addition of iron dosing. Slightly higher than the theoretical value of 1.5 mol of FeCl3 was required to precipitate 1 mol of dissolved sulfide inside the digester. Due to the high concentration of PO4(3-) in the digested sludge liquor, significantly higher iron is required for struvite precipitation. Iron dosing did not appear an economic solution for struvite control via iron phosphate formation. By taking advantage of the natural tendency of struvite formation in the digester liquid, it is possible to reduce the risk of struvite precipitation in and around the sludge-dewatering centrifuge by increasing the pH to precipitate struvite out before passing through the centrifuge. However, as the Mg2+/PO4(3-) molar ratio in digested sludge was low, by increasing the pH alone (using NaOH) the precipitation of PO4(3-) was limited by the amount of cations (Ca2+ and Mg2+) available in the sludge. Although this would reduce struvite precipitation in the centrifuge, it could not significantly reduce PO4(3-) recycling back to the plant. For long-term operation, maximum PO4(3-) reduction should be the ultimate aim to minimise PO4
MULTICRITERIА PROBLEM OF FINDING THE OPTIMAL PATHS FOR LARGE-SCALE TRANSPORT SYSTEM
Pavlov D. A.
2015-11-01
Full Text Available This article explores the multicriteria problems arise in the organization of routes in large-scale transport management system. As a mathematical tool for constructing a model, we were using the prefractal graphs. Prefractal graphs naturally reflect structure of the device of communications of transport system, reflecting its important features – locality and differentiation. Locality is provided with creation of internal routes (city, raionwide, etc.. Differentiation is understood as division of routes on intra regional, interregional and international. The objective is reduced to a covering of prefractal graphs by the simple paths which are crossed on edges and nodes. On the set of feasible solutions, vector criterion function with certain criteria is based. In concepts of transport system, the given criteria have concrete substantial interpretation, the transport routes allowing to design considering features of system. In this article, we construct polynomial algorithms for finding optimal according to certain criteria decision. By the criteria which aren't optimizing the allocated routes their estimates of the lower and upper bounds are given. On all given algorithms the estimates of computing complexity confirming advantage of use of methods of prefractal and fractal graphs before classical methods of the theory of graphs are constructed and proved
A Framing Link Based Tabu Search Algorithm for Large-Scale Multidepot Vehicle Routing Problems
Xuhao Zhang
2014-01-01
Full Text Available A framing link (FL based tabu search algorithm is proposed in this paper for a large-scale multidepot vehicle routing problem (LSMDVRP. Framing links are generated during continuous great optimization of current solutions and then taken as skeletons so as to improve optimal seeking ability, speed up the process of optimization, and obtain better results. Based on the comparison between pre- and postmutation routes in the current solution, different parts are extracted. In the current optimization period, links involved in the optimal solution are regarded as candidates to the FL base. Multiple optimization periods exist in the whole algorithm, and there are several potential FLs in each period. If the update condition is satisfied, the FL base is updated, new FLs are added into the current route, and the next period starts. Through adjusting the borderline of multidepot sharing area with dynamic parameters, the authors define candidate selection principles for three kinds of customer connections, respectively. Link split and the roulette approach are employed to choose FLs. 18 LSMDVRP instances in three groups are studied and new optimal solution values for nine of them are obtained, with higher computation speed and reliability.
Yekini Shehu
2010-01-01
real Banach space which is also uniformly smooth using the properties of generalized f-projection operator. Using this result, we discuss strong convergence theorem concerning general H-monotone mappings and system of generalized mixed equilibrium problems in Banach spaces. Our results extend many known recent results in the literature.
Genome-scale cold stress response regulatory networks in ten Arabidopsis thaliana ecotypes
Barah, Pankaj; Jayavelu, Naresh Doni; Rasmussen, Simon
2013-01-01
BACKGROUND: Low temperature leads to major crop losses every year. Although several studies have been conducted focusing on diversity of cold tolerance level in multiple phenotypically divergent Arabidopsis thaliana (A. thaliana) ecotypes, genome-scale molecular understanding is still lacking...... using Arabidopsis NimbleGen ATH6 microarrays. In total 6061 transcripts were significantly cold regulated (p majority of the transcripts (75%) showed ecotype specific expression pattern. By using sequence data...... available from Arabidopsis thaliana 1001 genome project, we further investigated sequence polymorphisms in the core cold stress regulon genes. Significant numbers of non-synonymous amino acid changes were observed in the coding region of the CBF regulon genes. Considering the limited knowledge about...
Stress analysis of 3D complex geometries using the scaled boundary polyhedral finite elements
Talebi, Hossein; Saputra, Albert; Song, Chongmin
2016-10-01
While dominating the numerical stress analysis of solids, the finite element method requires a mesh to conform to the surface of the geometry. Thus the mesh generation of three dimensional complex structures often require tedious human interventions. In this paper, we present a formulation for arbitrary polyhedral elements based on the scaled boundary finite element method, which reduces the difficulties in automatic mesh generation. We also propose a simple method to generate polyhedral meshes with local refinements. The mesh generation method is based on combining an octree mesh with surfaces defined using signed distance functions. Through several numerical examples, we verify the results, study the convergence behaviour and depict the many advantages and capabilities of the presented method. This contribution is intended to assist us to eventually frame a set of numerical methods and associated tools for the full automation of the engineering analysis where minimal human interaction is needed.
Viscosity scaling of fingering instability in finite slices with Korteweg stress
Pramanik, Satyajit
2015-01-01
We perform linear stability analyses (LSA) and direct numerical simulations (DNS) to investigate the influence of the dynamic viscosity on viscous fingering (VF) instability in miscible slices. Selecting the characteristic scales appropriately the importance of the magnitude of the dynamic viscosity of individual fluids on VF in miscible slice has been shown in the context of the transient interfacial tension. Further, we have confirmed this result for immiscible fluids and manifest the similarities between VF in immiscible and miscible slices with transient interfacial tension. In a more general setting, the findings of this letter will be very useful for multiphase viscous flow, in which the momentum balance equation contains an additional stress term free from the dynamic viscosity.
Cellular adaptation to biomechanical stress across length scales in tissue homeostasis and disease.
Gilbert, Penney M; Weaver, Valerie M
2016-09-15
Human tissues are remarkably adaptable and robust, harboring the collective ability to detect and respond to external stresses while maintaining tissue integrity. Following injury, many tissues have the capacity to repair the damage - and restore form and function - by deploying cellular and molecular mechanisms reminiscent of developmental programs. Indeed, it is increasingly clear that cancer and chronic conditions that develop with age arise as a result of cells and tissues re-implementing and deregulating a selection of developmental programs. Therefore, understanding the fundamental molecular mechanisms that drive cell and tissue responses is a necessity when designing therapies to treat human conditions. Extracellular matrix stiffness synergizes with chemical cues to drive single cell and collective cell behavior in culture and acts to establish and maintain tissue homeostasis in the body. This review will highlight recent advances that elucidate the impact of matrix mechanics on cell behavior and fate across these length scales during times of homeostasis and in disease states.
Cross-cultural validation of the Depression Anxiety Stress Scale-21 in China.
Wang, Kui; Shi, Hai-Song; Geng, Fu-Lei; Zou, Lai-Quan; Tan, Shu-Ping; Wang, Yi; Neumann, David L; Shum, David H K; Chan, Raymond C K
2016-05-01
The gap between the demand and delivery of mental health services in mainland China can be reduced by validating freely available and psychometrically sound psychological instruments. The present research examined the Chinese version of the 21-item Depression Anxiety Stress Scales (DASS-21). Study 1 administered the DASS-21 to 1,815 Chinese college students and found internal consistency indices (Cronbach's alpha) of .83, .80, and .82 for the Depression, Anxiety, and Stress subscales, respectively, and .92 for the total DASS total. Test-retest reliability over a 6-month interval was .39 to .46 for each of the 3 subscales and .46 for the total DASS. Moderate convergent validity of the Depression and Anxiety subscales was demonstrated via significant correlations with the Chinese Beck Depression Inventory (r = .51 at Time 1 and r = .64 at Time 2) and the Chinese State-Trait Anxiety Inventory (r = .41), respectively. Confirmatory factor analyses supported the original 3-factor model with 1 minor change (nonnormed fit index [NNFI] = .964, comparative fit index [CFI] = .968, and root mean square error of approximation [RMSEA] = .079). Study 2 examined the clinical utility of the Chinese DASS-21 in 166 patients with schizophrenia and 90 matched healthy controls. Patients had higher Depression and Anxiety but not Stress subscale scores than healthy controls. A discriminant function composed of the linear combination of 3 subscale scores correctly discriminated 69.92% of participants, which again supported the potential clinical utility of the DASS in mainland China. Taken together, findings in these studies support the cross-cultural validity of the DASS-21 in China. (PsycINFO Database Record
A Scaled Underwater Launch System Accomplished by Stress Wave Propagation Technique
WEI Yan-Peng; WANG Yi-Wei; FANG Xin; HUANG Cheng-guang; DUAN Zhu-Ping
2011-01-01
A scaled underwater launch system based on the stress wave theory and the slip Hopkinson pressure bar (SHPB)technique is developed to study the phenomenon of cavitations and other hydrodynamic features of high-speed submerged bodies. The present system can achieve a transient acceleration in the water instead of long-time acceleration outside the water. The projectile can obtain a maximum speed of 30m/s in about 200μs by the SHPB launcher. The cavitation characteristics in the stage of acceleration and deceleration are captured by the high-speed camera. The processes of cavitation inception, development and collapse are also simulated with the business software FLUENT, and the results are in good agreement with experiment. There is about 20-30％energy loss during the launching processes, the mechanism of energy loss is also preliminary investigated by measuring the energy of the incident bar and the projectile.%@@ A scaled underwater launch system based on the stress wave theory and the slip Hopkinson pressure bar (SHPB) technique is developed to study the phenomenon of cavitations and other hydrodynamic features of high-speed submerged bodies.The present system can achieve a transient acceleration in the water instead of long-time acceleration outside the water.The projectile can obtain a maximum speed of 30m/s in about 200 μs by the SHPB launcher.The cavitation characteristics in the stage of acceleration and deceleration are captured by the high-speed camera.
谢腊兵; 江福汝
2003-01-01
The method of boundary layer with multiple scales and computer algebra were applied to study the asymptotic behavior of solution of boundary value problems for a class of system of nonlinear differential equations. The asymptotic expansions of solution were constructed. The remainders were estimated. And an example was analysed. It provides a new foreground for the application of the method of boundary layer with multiple scales.
A new theoretical model of the quasistatic single-fiber pullout problem: Analysis of stress field
Qing, Hai
2013-01-01
results of the stress distributions, in both fully bonded region and fully debonded region, are presented for a typical glass/epoxy composite system with different fibre volume fraction and model length. In fully bonded region, the theoretical results from present model are more accurate compared......A new theoretical model is developed in order to predict the stress transfer during the quasistatic single-fibre pullout process. The theoretical approach retains all relevant stress and strain components, and satisfies exactly the interfacial continuity conditions and all the stress boundary...... conditions. For both matrix and fibre, the equilibrium equations along radial direction are satisfied strictly, while the equilibrium equations along axial direction are satisfied in the integral forms. Three normal stress-strain relationships are strictly satisfied, while the radial displacement gradient...
Neece, Cameron L.
2014-01-01
Background: Parents of children with developmental delays (DD) typically report elevated levels of parental stress compared with parents of typically developing children. Children with DD are also at high risk for exhibiting significant behaviour problems. Parental stress has been shown to impact the development of these behaviour problems;…
Linda, Wendy P; Marroquín, Brett; Miranda, Regina
2012-01-01
This study examined whether active problem solving would buffer against, whereas passive problem solving would exacerbate, the association of negative life stress with suicidal ideation. Young adult college students (73 females, M(age) = 19.0) from a diverse urban public university, with (n = 37) and without (n = 59) a suicide attempt history completed measures of life stress, problem solving, hopelessness, depression, and suicidal ideation. Hierarchical linear regressions were conducted to test moderating roles of active and passive problem solving, along with suicide attempt history, on the relation between negative life event stress and suicidal ideation. There was a weaker relation between life stress and suicidal ideation at high and average levels of relevant problem solving than at low levels, and this was the case primarily for suicide attempters but not for non-attempters. Individuals with a past attempt produced more passive solutions than non-attempters, but among attempters, even passive problem solving buffered the association of life stress with suicidal ideation. Relevant problem solving in the face of life stress may be especially important for individuals vulnerable to suicidal ideation due to an attempt history. Among such at-risk individuals, generating even passive solutions in the face of life stress may be more adaptive than generating few solutions. Thus, clinical interventions with suicide attempters that focus on generating solutions to problems, even if these are initially passive, may help mitigate the effect of life stress on suicidal ideation.
Repeat prescribing: scale, problems and quality management in ambulatory care patients.
De Smet, Peter A G M; Dautzenberg, Maaike
2004-01-01
The reported scale of repeat prescriptions ranges from 29% to 75% of all items prescribed, depending on the definition of repeat prescribing and other variables. It is likely that a substantial part of repeat prescribing by general practitioners (GPs) occurs without direct doctor-patient contact. While this reduces the workload for the GP and is convenient for the patient, it does not provide the adequate control that is needed to ensure that every repeat prescription is still appropriate, effective and well tolerated, and that it is still being viewed upon and taken by the patient as intended. Infrequent therapy reviews may lead to failure to prevent, identify and solve drug-related problems and drug wastage, and may, thereby, have a negative impact on the effectiveness, safety or cost of the medications prescribed. Studies evaluating the repeat prescribing process have shown that GPs and medical practices vary widely in their degree of administrative and clinical control of repeat prescriptions. Contrary to the opinion that GPs cannot change prescribing behaviour when the prescription is initiated by a medical specialist, GPs have their own responsibility for controlling the repeats of such prescriptions. Intervention studies suggest that a medication review by a pharmacist can help to reduce drug-related problems with repeat prescriptions, and the effectiveness of the intervention may be increased by combining the medication review with a consultation of the patient's medical records and a patient interview. In several studies, such an intervention was relatively inexpensive and, therefore, feasible. However, these conclusions should be viewed with appropriate caution because a number of caveats pertain. There is still no evidence that these types of intervention improve health-related quality of life or reduce healthcare cost, and so far only a few trials have produced any evidence of clinical improvement. As implicit and explicit screening criteria have their
Guerain, M.; Goudeau, P.; Grosseau-Poussard, J. L.
2011-11-01
Stress release phenomena are studied for α-Cr2O3 thermal oxide films grown on NiCr-30 alloys. The influence of specific metallurgical parameters, such as cooling rate and initial surface roughness, is investigated thanks to Raman spectroscopy. Systematic correlations are established between the residual stress level in the scales and the damage rate resulting from a delamination process by buckling. Different buckling morphologies are characterized mainly according to the cooling rate range.
Hairul Anuar Hashim; Freddy Golok; Rosmatunisah Ali
2011-01-01
Background: Psychometrically sound measurement instrument is a fundamental requirement across broad range of research areas. In negative affect research, Depression Anxiety Stress Scale (DASS) has been identified as a psychometrically sound instrument to measure depression, anxiety and stress, especially the 21-item version. However, its psychometric properties in adolescents have been less consistent. Objectives: Thus, the present study sought to examine the factorial validity and internal c...
Yunjuan WANG; Detong ZHU
2008-01-01
Based on a differentiable merit function proposed by Taji et al.in "Math.Prog. Stud.,58,1993,369-383",the authors propose an affine scaling interior trust region strategy via optimal path to modify Newton method for the strictly monotone variational inequality problem subject to linear equality and inequality constraints.By using the eigensystem decomposition and affine scaling mapping,the authors form an affine scaling optimal curvilinear path very easily in order to approximately solve the trust region subproblem.Theoretical analysis is given which shows that the proposed algorithm is globally convergent and has a local quadratic convergence rate under some reasonable conditions.
Large scale stochastic inventory routing problems with split delivery and service level constraints
Y. Yu (Yugang); C. Chu (Chengbin); H.X. Chen (Haoxun); F. Chu (Feng)
2010-01-01
textabstractA stochastic inventory routing problem (SIRP) is typically the combination of stochastic inventory control problems and NP-hard vehicle routing problems, which determines delivery volumes to the customers that the depot serves in each period, and vehicle routes to deliver the volumes. Th
Large scale stochastic inventory routing problems with split delivery and service level constraints
Y. Yu (Yugang); C. Chu (Chengbin); H.X. Chen (Haoxun); F. Chu (Feng)
2012-01-01
textabstractA stochastic inventory routing problem (SIRP) is typically the combination of stochastic inventory control problems and NP-hard vehicle routing problems, which determines delivery volumes to the customers that the depot serves in each period, and vehicle routes to deliver the volumes. Th
Y. Yu (Yugang); C. Chu (Chengbin); H.X. Chen (Haoxun); F. Chu (Feng)
2010-01-01
textabstractA stochastic inventory routing problem (SIRP) is typically the combination of stochastic inventory control problems and NP-hard vehicle routing problems, for a depot to determine delivery volumes to its customers in each period, and vehicle routes to distribute the delivery volumes. This
Schmeck, Annett; Opfermann, Maria; van Gog, Tamara; Paas, Fred; Leutner, Detlev
2015-01-01
Subjective cognitive load (CL) rating scales are widely used in educational research. However, there are still some open questions regarding the point of time at which such scales should be applied. Whereas some studies apply rating scales directly after each step or task and use an average of these
Schmeck, Annett; Opfermann, Maria; van Gog, Tamara; Paas, Fred; Leutner, Detlev
2015-01-01
Subjective cognitive load (CL) rating scales are widely used in educational research. However, there are still some open questions regarding the point of time at which such scales should be applied. Whereas some studies apply rating scales directly after each step or task and use an average of these
Deswal, Sunita; Kalkal, Kapil Kumar; Sheoran, Sandeep Singh
2016-09-01
A mathematical model of fractional order two-temperature generalized thermoelasticity with diffusion and initial stress is proposed to analyze the transient wave phenomenon in an infinite thermoelastic half-space. The governing equations are derived in cylindrical coordinates for a two dimensional axi-symmetric problem. The analytical solution is procured by employing the Laplace and Hankel transforms for time and space variables respectively. The solutions are investigated in detail for a time dependent heat source. By using numerical inversion method of integral transforms, we obtain the solutions for displacement, stress, temperature and diffusion fields in physical domain. Computations are carried out for copper material and displayed graphically. The effect of fractional order parameter, two-temperature parameter, diffusion, initial stress and time on the different thermoelastic and diffusion fields is analyzed on the basis of analytical and numerical results. Some special cases have also been deduced from the present investigation.
Romelsjö, A; Hasin, D; Hilton, M
1992-01-01
The relationship between 15 measures of stressful working conditions and high alcohol consumption (35 g 100% ethanol per day or more for men and 25 g or more for women) was studied, using cross-sectional data from a general population survey of 1344 males and 1494 females; the ages 25-64 years...... increased odds ratios were lower when subjects with an alcohol diagnosis at inpatient care during 1980-84 were excluded in the analyses. On the whole, our findings are not conclusive. The strong, but imprecise associations between stressful working conditions and severe alcohol problems, are however......-adjusted odds ratios, were positive and some were negative when high alcohol consumption was the endpoint, but there was a clear variation by sex and social class. Generally the positive associations were stronger among male non-manual employees. Among males, there was a clear association between stressful...
Ali Yousif Alzaeem
2010-07-01
Full Text Available Background & Objectives: Stress results from perception of individual to external threats. Stress in academic life affects all college students regardless of their programs. It has been well established in many studies that pharmacy students suffer a massy amount of stress but empirical evidence with regard to how much stress affects pharmacy students and how they cope with it is still needed. The present paper vows constructing a special tool to be used in gauging stress of pharmacy undergraduates.Method: The Stress in Academic Life Scale (SALS was answered by 388 Malaysian pharmacy undergraduate students from Universiti Sains Malaysia (USM during an experimental session. Face validity was obtained earlier in an extensive pilot study involving 100 participants. Content validity was established along with piloting. Exploratory factor analysis was conducted to confirm the multi-dimensional structure and further validity. Principal component factor extraction with Varimax rotation had decided the final factors matrix and items loading.Results: Reliability for SALS measured by Cronbach’s α coefficient was 0.860 (ranging from 0.501 to 0.701 for the factors. All correlations between the factors were significant (p Conclusion: Outcome of validity tests, reliability, and correlational matrices had all demonstrated statistical stability for SALS as a scale. Diversity of stressors from academic, emotional, social, and other interactions which embraces the academic life in pharmacy school make SALS applicable for usage to measure stress specifically among pharmacy undergraduate students.
Zeytinogla, Isik Uurla; Seaton, M Bianca; Lillevik, Waheeda; Moruz, Josefina
2005-01-01
Women workers dominate the labor market of part-time and casual jobs in Canada and other industrialized countries, particularly in the retail trade and consumer services sector. However, research into the occupational health consequences of part-time and casual jobs for this large group of women workers is still in its early stages. Emerging evidence suggests that part-time and casual jobs contribute to stress and result in health problems for women. To learn about the impact of part-time and casual jobs on women's experiences of stress and their resulting physical and emotional health, we conducted interviews and focus groups with occupational health and safety union representatives and female workers in retail and consumer services. Results show that stress is a major occupational health problem for these women, due to the working conditions in part-time and casual jobs, the psychosocial work environment, and the gendered work environment in the retail trade and consumer services. Stress from part-time and casual jobs results in repetitive strain injuries, migraine headaches, and feelings of low self-esteem, low motivation, and job dissatisfaction for women. The disconcerting implication of our research is that part-time and casual employment comes at a cost for some women.
Daniel T.L. Shek
2006-01-01
Full Text Available This paper outlines the proposal for the development, implementation, and evaluation of a positive youth development program that attempts to promote the mental health of stressful Chinese adolescents using principles of Problem Solving Therapy (PST. There are two general aims of PST: to help clients identify life difficulties and resolve them, as well as to teach them skills on how to deal with future problems. The proposed project will utilize the principles of PST as the guiding framework to run two mental health promotion courses for adolescents who are experiencing disturbing stressful responses and students who want to improve their stress management style. Both objective and subjective outcome evaluation strategies will be carried out to assess the effectiveness of the intervention to promote the psychological well-being in adolescents who are experiencing stress. A related sample proposal is described that can give social workers some insight on how to prepare a proposal for developing the Tier 2 Program of the Project P.A.T.H.S. (Positive Adolescent Training through Holistic Social Programs.
AN EFFECTIVE CONTINUOUS ALGORITHM FOR APPROXIMATE SOLUTIONS OF LARGE SCALE MAX-CUT PROBLEMS
Cheng-xian Xu; Xiao-liang He; Feng-min Xu
2006-01-01
An effective continuous algorithm is proposed to find approximate solutions of NP-hard max-cut problems. The algorithm relaxes the max-cut problem into a continuous nonlinear programming problem by replacing n discrete constraints in the original problem with one single continuous constraint. A feasible direction method is designed to solve the resulting nonlinear programming problem. The method employs only the gradient evaluations of the objective function, and no any matrix calculations and no line searches are required.This greatly reduces the calculation cost of the method, and is suitable for the solution of large size max-cut problems. The convergence properties of the proposed method to KKT points of the nonlinear programming are analyzed. If the solution obtained by the proposed method is a global solution of the nonlinear programming problem, the solution will provide an upper bound on the max-cut value. Then an approximate solution to the max-cut problem is generated from the solution of the nonlinear programming and provides a lower bound on the max-cut value. Numerical experiments and comparisons on some max-cut test problems (small and large size) show that the proposed algorithm is efficient to get the exact solutions for all small test problems and well satisfied solutions for most of the large size test problems with less calculation costs.
Solving Large-Scale Computational Problems Using Insights from Statistical Physics
Selman, Bart [Cornell University
2012-02-29
Many challenging problems in computer science and related fields can be formulated as constraint satisfaction problems. Such problems consist of a set of discrete variables and a set of constraints between those variables, and represent a general class of so-called NP-complete problems. The goal is to find a value assignment to the variables that satisfies all constraints, generally requiring a search through and exponentially large space of variable-value assignments. Models for disordered systems, as studied in statistical physics, can provide important new insights into the nature of constraint satisfaction problems. Recently, work in this area has resulted in the discovery of a new method for solving such problems, called the survey propagation (SP) method. With SP, we can solve problems with millions of variables and constraints, an improvement of two orders of magnitude over previous methods.
Rongo, L.M.B.; Barten, F.J.M.H.; Msamanga, G.I.; Heederik, D.; Dolmans, W.M.V.
2004-01-01
BACKGROUND: Workers in informal small-scale industries (SSI) in developing countries involved in welding, spray painting, woodwork and metalwork are exposed to various hazards with consequent risk to health. Aim To assess occupational exposure and health problems in SSI in Dar es Salaam, Tanzania.
Psychometric Analyses of the Problem-Focused Style of Coping (PF-SOC) Scale with Taiwanese Samples
Chang, Yuhsuan; Lan, Yu-Ling; Lin, Hung-Yu; Heppner, Puncky Paul
2012-01-01
The current research comprises two samples that investigated the psychometric properties of the Problem-Focused Style of Coping (PF-SOC; Heppner, Cook, Wright, & Johnson) scale using two Taiwanese samples. In Sample 1 (N = 809), we investigated the structural dimensions of the PF-SOC using a principal component analysis (PCA) and confirmed…
Habtu, Solomon; Ludi, Eva; Jamin, Jean Yves; Oates, Naomi; Fissahaye Yohannes, Degol
2014-05-01
Practicing various innovations pertinent to irrigated farming at local field scale is instrumental to increase productivity and yield for small holder farmers in Africa. However the translation of innovations from local scale to the scale of a jointly operated irrigation scheme is far from trivial. It requires insight on the drivers for adoption of local innovations within the wider farmer communities. Participatory methods are expected to improve not only the acceptance of locally developed innovations within the wider farmer communities, but to allow also an estimation to which extend changes will occur within the entire irrigation scheme. On such a base, more realistic scenarios of future water productivity within an irrigation scheme, which is operated by small holder farmers, can be estimated. Initial participatory problem and innovation appraisal was conducted in Gumselassa small scale irrigation scheme, Ethiopia, from Feb 27 to March 3, 2012 as part of the EAU4FOOD project funded by EC. The objective was to identify and appraise problems which hinder sustainable water management to enhance production and productivity and to identify future research strategies. Workshops were conducted both at local (Community of Practices) and regional (Learning Practice Alliance) level. At local levels, intensive collaboration with farmers using participatory methods produced problem trees and a "Photo Safari" documented a range of problems that negatively impact on productive irrigated farming. A range of participatory methods were also used to identify local innovations. At regional level a Learning Platform was established that includes a wide range of stakeholders (technical experts from various government ministries, policy makers, farmers, extension agents, researchers). This stakeholder group did a range of exercise as well to identify major problems related to irrigated smallholder farming and already identified innovations. Both groups identified similar problems
La versión castellana de la escala "the nursing stress scale". proceso de adaptación transcultural
Más Pons Rosa
1998-01-01
Full Text Available FUNDAMENTO: Adaptación transcultural de la escala de medida de estresores laborales en personal de enfermería hospitalario "The Nursing Stress Scale". MÉTODOS: Se ha utilizado el método de traducción-retrotraducción complementado con metodología cualitativa (grupos de discusión. La escala original fue traducida al castellano de forma independiente por dos enfermeras bilingües de origen español que habían residido en Estados Unidos. A continuación se llevó a cabo la retrotraducción al inglés por dos traductores de origen norteamericano residentes en España. Se realizaron 2 grupos de discusión; uno compuesto por enfermeras/os y otro por auxiliares de enfermería de distintos servicios y hospitales. Por último, se realizó una encuesta piloto en 20 profesionales de enfermería. RESULTADOS: Los ítems fueron clasificados según la dificultad en encontrar una expresión en castellano conceptualmente equivalente a la original; 15 ítems no presentaron ninguna dificultad, en 13 ítems fue moderada y en 6 alta. Tras una nueva traducción de los ítems problemáticos y las consultas realizadas a uno de los autores de la escala original, se obtuvo una versión en castellano en la que 12 ítems presentaban dos o más versiones alternativas, que fueron valoradas posteriormente en la encuesta piloto. Como resultado de los grupos de discusión se concluyó que los estresores laborales percibidos por el personal de enfermería son equiparables a los contenidos en la escala original exceptuando el ítem "Avería del ordenador" que no resulta procedente en nuestro medio. CONCLUSIÓN: Se ha obtenido una versión adaptada en castellano de la escala The Nursing Stress Scale, siendo necesaria la evaluación posterior de su validez y fiabilidad.
Wilson, Sarah M; Gilmore, Amanda K; Rhew, Isaac C; Hodge, Kimberley A; Kaysen, Debra L
2016-10-01
Compared to sexual minority men and heterosexual women, sexual minority women report elevated alcohol use in young adulthood. Heavy alcohol use and alcohol use disorders disproportionately affect sexual minority women across the lifespan, yet there is limited research investigating reasons for such associations. The present study investigates longitudinal associations between minority stress and both alcohol use as well as self-rated drinking consequences. Participants (N=1057) were self-identified lesbian (40.5%) and bisexual (59.5%) women between the ages of 18 to 25 recruited from across the U.S. using online advertisements. Participants completed four annual surveys. Hurdle mixed effects models were used to assess associations between minority stress and typical weekly drinking and drinking consequences one year later. Minority stress was not significantly associated with subsequent typical drinking. However, minority stress was significantly associated with having any alcohol consequences as well as the count of alcohol consequences one year later after controlling for covariates. Consistent with extant literature, this study provides evidence for a prospective association between minority stress experienced by sexual minority women and drinking consequences. This study also provides support for the potential impact of efforts to reduce minority stress faced by sexual minority women.
Smith, Victoria C; Leppert, Katherine A; Alfano, Candice A; Dougherty, Lea R
2014-08-01
Using a multi-method design, this study examined the construct validity of the Parent-Child Sleep Interactions Scale (PSIS; Alfano et al., 2013), which measures sleep-related parenting behaviors and interactions that contribute to preschoolers' sleep problems. Participants included a community sample of 155 preschoolers (ages 3-5years; 51.6% female). Primary caregivers completed the PSIS. Parenting styles and behaviors were assessed with laboratory observations and parent reports. Parent and child psychopathology and family life stress were assessed with clinical interviews and parent reports. Bivariate correlations revealed significant associations between the PSIS and a number of variables, including lower observed parental support and quality of instruction; higher observed parental intrusiveness; authoritative, authoritarian, and permissive parenting styles; current maternal depressive and/or anxiety disorders and depressive symptomatology; increased stressful life events; lower marital satisfaction; and higher child depressive, anxiety, attention-deficit/hyperactivity disorder (ADHD), and oppositional defiant disorder (ODD) symptoms. The patterns of association varied based on the specific PSIS scale. The PSIS demonstrates meaningful associations with parenting, maternal psychopathology, family stress, and child psychopathology and functioning. Findings suggest that the PSIS is a valid measure for assessing sleep-related parent/child behaviors and interactions among preschoolers, suited to real-world settings. Copyright © 2014 Elsevier B.V. All rights reserved.
无
2007-01-01
A modified bottleneck-based (MB) heuristic for large-scale job-shop scheduling problems with a welldefined bottleneck is suggested,which is simpler but more tailored than the shifting bottleneck (SB) procedure.In this algorithm,the bottleneck is first scheduled optimally while the non-bottleneck machines are subordinated around the solutions of the bottleneck schedule by some effective dispatching rules.Computational results indicate that the MB heuristic can achieve a better tradeoff between solution quality and computational time compared to SB procedure for medium-size problems.Furthermore,it can obtain a good solution in a short time for large-scale job-shop scheduling problems.
Yingni Zhai
2014-10-01
Full Text Available Purpose: A decomposition heuristics based on multi-bottleneck machines for large-scale job shop scheduling problems (JSP is proposed.Design/methodology/approach: In the algorithm, a number of sub-problems are constructed by iteratively decomposing the large-scale JSP according to the process route of each job. And then the solution of the large-scale JSP can be obtained by iteratively solving the sub-problems. In order to improve the sub-problems' solving efficiency and the solution quality, a detection method for multi-bottleneck machines based on critical path is proposed. Therewith the unscheduled operations can be decomposed into bottleneck operations and non-bottleneck operations. According to the principle of “Bottleneck leads the performance of the whole manufacturing system” in TOC (Theory Of Constraints, the bottleneck operations are scheduled by genetic algorithm for high solution quality, and the non-bottleneck operations are scheduled by dispatching rules for the improvement of the solving efficiency.Findings: In the process of the sub-problems' construction, partial operations in the previous scheduled sub-problem are divided into the successive sub-problem for re-optimization. This strategy can improve the solution quality of the algorithm. In the process of solving the sub-problems, the strategy that evaluating the chromosome's fitness by predicting the global scheduling objective value can improve the solution quality.Research limitations/implications: In this research, there are some assumptions which reduce the complexity of the large-scale scheduling problem. They are as follows: The processing route of each job is predetermined, and the processing time of each operation is fixed. There is no machine breakdown, and no preemption of the operations is allowed. The assumptions should be considered if the algorithm is used in the actual job shop.Originality/value: The research provides an efficient scheduling method for the
Cross-Culture Validation of the HIV/AIDS Stress Scale: The Development of a Revised Chinese Version.
Niu, Lu; Qiu, Yangyang; Luo, Dan; Chen, Xi; Wang, Min; Pakenham, Kenneth I; Zhang, Xixing; Huang, Zhulin; Xiao, Shuiyuan
2016-01-01
Being HIV-infected is a stressful experience for many individuals. To assess HIV-related stress in the Chinese context, a measure with satisfied psychometric properties is yet underdeveloped. This study aimed to examine the psychometric characteristics of a simplified Chinese version of the HIV/AIDS Stress Scale (SS-HIV) among people living with HIV/AIDS in central China. A total of 667 people living with HIV (92% were male) were recruited from March 1st 2014 to August 31th 2015 by consecutive sampling. A standard questionnaire package containing the Chinese HIV/AIDS Stress Scale (CSS-HIV), the Chinese Patient Health Questionnaire-9 (PHQ-9), and the Chinese Generalized Anxiety Disorder Scale (GAD-7) were administered to all participants, and 38 of the participants were selected randomly to be re-tested in four weeks after the initial testing. Our data supported that a revised 17-item CSS-HIV had adequate psychometric properties. It consisted of 3 factors: emotional stress (6 items), social stress (6 items) and instrumental stress (5 items). The overall Cronbach's α was 0.906, and the test-retest reliability coefficient was 0.832. The revised CSS-HIV was significantly correlated with the number of HIV-related symptoms, as well as scores on the PHQ-9 and GAD-7, indicating acceptable concurrent validity. The 17-item Chinese version of the SS-HIV has potential research and clinical utility in identifying important stressors among the Chinese HIV-infected population and in understanding the effects of stress on adjustment to HIV.
Helmuth, Brian; Broitman, Bernardo R; Yamane, Lauren; Gilman, Sarah E; Mach, Katharine; Mislan, K A S; Denny, Mark W
2010-03-15
Predicting when, where and with what magnitude climate change is likely to affect the fitness, abundance and distribution of organisms and the functioning of ecosystems has emerged as a high priority for scientists and resource managers. However, even in cases where we have detailed knowledge of current species' range boundaries, we often do not understand what, if any, aspects of weather and climate act to set these limits. This shortcoming significantly curtails our capacity to predict potential future range shifts in response to climate change, especially since the factors that set range boundaries under those novel conditions may be different from those that set limits today. We quantitatively examine a nine-year time series of temperature records relevant to the body temperatures of intertidal mussels as measured using biomimetic sensors. Specifically, we explore how a 'climatology' of body temperatures, as opposed to long-term records of habitat-level parameters such as air and water temperatures, can be used to extrapolate meaningful spatial and temporal patterns of physiological stress. Using different metrics that correspond to various aspects of physiological stress (seasonal means, cumulative temperature and the return time of extremes) we show that these potential environmental stressors do not always occur in synchrony with one another. Our analysis also shows that patterns of animal temperature are not well correlated with simple, commonly used metrics such as air temperature. Detailed physiological studies can provide guidance to predicting the effects of global climate change on natural ecosystems but only if we concomitantly record, archive and model environmental signals at appropriate scales.
Refraction of the principal stress trajectories at a surface of discontinuity and related problems
Mukhamediev, Shamil
2014-05-01
The principal stress trajectories (PST) obtainable from the inversion of data on various types of coeval natural stress indicators provide important information on the real stress fields of the Earth's crust. In particular, once the PST field has been obtained, the stress field can be calculated from equilibrium conditions without regard to the crust rheological properties. In the case under consideration the equilibrium conditions form a closed hyperbolic system of differential equations on unknown magnitudes of the principal stresses. The PST concept is significantly complicated in presence of faults, natural interfaces, and other surfaces of discontinuity where according to laboratory experiments and drilling results the stress trajectories are usually refracted. Unfortunately, the phenomenon of the PST refraction is poorly understood theoretically and often ignored in mathematical modelling which leads to unjustified conclusions. The full investigation of the phenomenon has been carried out for discontinuity surface D for which we distinguish "+" and "-" sides. Inclinations of axes of the extreme principal stresses T1 and T3 (T1 >T3, tension is positive) from both sides are different but should be potentially compatible which means existence of stress magnitudes ensuring equilibrium. To check the compatibility of axes at any point, they should be orthogonally projected in a special way onto the plane tangent to the surface. This yields the so-called shear sectors S+ and S- containing all the possible shear stress direction vectors p+ and p-, |p+| = |p-|=1, at a local point. The T1 and T3 axes from both sides are potentially compatible if and only if the intersection of S- and S+ is nonempty. Indeed, if the intersection is empty the necessary condition of equilibrium, p-=p+, cannot be fulfilled. Let now the S- sector with the central angle ϕ- be given at any point on the surface D. Then possible orientations of the T1 and T3 axes at this point from the "+" side
Quaglia, Alberto; Sarup, Bent; Sin, Gürkan;
2013-01-01
The formulation of Enterprise-Wide Optimization (EWO) problems as mixed integer nonlinear programming requires collecting, consolidating and systematizing large amount of data, coming from different sources and specific to different disciplines. In this manuscript, a generic and flexible data...... structure for efficient formulation of enterprise-wide optimization problems is presented. Through the integration of the described data structure in our synthesis and design framework, the problem formulation workflow is automated in a software tool, reducing time and resources needed to formulate large...... problems, while ensuring at the same time data consistency and quality at the application stage....
Experimental scale model study of cracking in brick masonry under tensile and shear stress
Gálvez Ruiz, J. C.
2008-09-01
Full Text Available This article discusses the results of research conducted on the failure behaviour of brick masonry under tensile and shear stress. The study was designed to develop test models and generate experimental results able to provide greater insight into tensile and shear stresses cracking in brick masonry. The results of a campaign conducted with two types of specimens are discussed: 1 double-edge notched specimens under non-symmetrical compression stress, and 2 three point bending specimens under nonsymmetrical loading. Tests were run on specimens of similar size (similarity rate 2 and different bed joint orientation to determine how bed joint orientation affects crack propagation. The tests were conducted on scale models (1/4 of a single wythe, stretcher bond brickwork masonry wall one half foot thick.Este artículo presenta los resultados de la investigación realizada sobre el comportamiento en rotura de la fábrica de ladrillo bajo solicitaciones de tracción y cortante. La investigación está encaminada a proporcionar modelos de ensayo y resultados experimentales que permitan conocer mejor los procesos de agrietamiento de la fábrica de ladrillo bajo tensiones normales de tracción y tangenciales. Se presentan los resultados de una campaña experimental desarrollada con dos tipos de probeta: 1 la probeta compacta con doble entalla solicitada a compresión asimétrica, y 2 la probeta de flexión con entalla solicitada bajo carga asimétrica aplicada en tres puntos. Se han ensayado probetas de dos tamaños semejantes (razón de semejanza 2 y varias orientaciones de los tendeles, con el fin de ver cómo afecta la orientación de los tendeles en la propagación de las grietas. Los ensayos se han realizado con probetas a escala 1/4 de un muro de fábrica de ladrillo de una hoja a soga de medio pie de espesor.
Gunnarsdóttir, Hrafnhildur; Hensing, Gunnel; Povlsen, Lene; Petzold, Max
2016-04-01
The Nordic welfare system has been acknowledged as favourable for children, successfully contributing to low child mortality and poverty rates. Nevertheless, mental health problems among children and adolescents are common and the economic situation of the family has been highlighted as an important determinant. In spite of similar social, political and cultural structures, the Nordic countries differ; Iceland was most affected by the global financial crisis in 2008. The aim of this study was to examine potential differences in parental financial stress and the associations to child mental health between the Nordic countries as well as age and gender differences. The study sample consisted of 6330 children aged 4-16 years old included in the 2011 version of the Nordic Study of Children's Health, Wellbeing and Quality of life. The Strengths and Difficulties Questionnaire was used to measure mental health problems. In Iceland, 47.7% of the parents reported financial stress while ≤20% did so in the other countries except for Finland (33.5%). However, in case of parental financial stress the OR of mental health problems comparing children to parents with and without financial stress was significantly lower among the Icelandic children (OR 1.60, 95% CI 1.15-2.24) than among the others: Denmark OR 3.07 (95% CI 2.15-4.39), Finland OR 2.28 (95% CI 1.60-3.25), Norway OR 2.77 (95% CI 1.86-4.12), Sweden OR 3.31(95% CI 2.26-4.86). No significant age or gender differences in the ORs were observed. Besides socioeconomic situation, relative deprivation should be considered an important determinant of child mental health. © The Author 2015. Published by Oxford University Press on behalf of the European Public Health Association. All rights reserved.
Babel, Kimberly A; Jambroes, Tijs; Oostermeijer, Sanne; van de Ven, Peter M; Popma, Arne; Vermeiren, Robert R J M; Doreleijers, Theo A H; Jansen, Lucres M C
2016-01-01
Attenuated activity of stress-regulating systems has consistently been reported in boys with conduct problems. Results in studies of girls are inconsistent, which may result from the high prevalence of comorbid post-trauma symptoms. Therefore, the aim of the present study is to investigate post-trauma symptoms as a potential mediator in the relation between stress-regulation systems functioning and conduct problems in female adolescents. The sample consisted of 78 female adolescents (mean age 15.4; SD 1.1) admitted to a closed treatment institution. The diagnosis of disruptive behaviour disorder (DBD) was assessed by a structured interview-the diagnostic interview schedule for children version IV (DISC-IV). To assess post-trauma symptoms and externalizing behaviour problems, self-report questionnaires, youth self report (YSR) and the trauma symptom checklist for Children (TSCC) were used. The cortisol awakenings response (CAR) measured hypothalamic-pituitary-adrenal (HPA) axis activity, whereas autonomous nervous system (ANS) activity was assessed by heart rate (HR), pre-ejection period (PEP) and respiratory sinus arrhythmia (RSA). Independent t-tests were used to compare girls with and without DBD, while path analyses tested for the mediating role of post- trauma symptoms in the relation between stress regulating systems and externalizing behaviour. Females with DBD (n = 37) reported significantly higher rates of post-trauma symptoms and externalizing behaviour problems than girls without DBD (n = 39). Path analysis found no relation between CAR and externalizing behaviour problems. With regard to ANS activity, positive direct effects on externalizing behaviour problems were present for HR (standardized β = 0.306, p = 0.020) and PEP (standardized β = -0.323, p = 0.031), though not for RSA. Furthermore, no relation-whether direct or indirect-could be determined from post-trauma symptoms. Present findings demonstrate that the neurobiological
Pabon, Rommel; Barnard, Casey; Ukeiley, Lawrence; Sheplak, Mark
2016-11-01
Particle image velocimetry (PIV) and fluctuating wall shear stress experiments were performed on a flat plate turbulent boundary layer (TBL) under zero pressure gradient conditions. The fluctuating wall shear stress was measured using a microelectromechanical 1mm × 1mm floating element capacitive shear stress sensor (CSSS) developed at the University of Florida. The experiments elucidated the imprint of the organized motions in a TBL on the wall shear stress through its direct measurement. Spatial autocorrelation of the streamwise velocity from the PIV snapshots revealed large scale motions that scale on the order of boundary layer thickness. However, the captured inclination angle was lower than that determined using the classic method by means of wall shear stress and hot-wire anemometry (HWA) temporal cross-correlations and a frozen field hypothesis using a convection velocity. The current study suggests the large size of these motions begins to degrade the applicability of the frozen field hypothesis for the time resolved HWA experiments. The simultaneous PIV and CSSS measurements are also used for spatial reconstruction of the velocity field during conditionally sampled intense wall shear stress events. This material is based upon work supported by the National Science Foundation Graduate Research Fellowship under Grant No. DGE-1315138.
Eskildsen, Anita; Dalgaard, Vita Ligaya; Nielsen, Kent Jacob;
2015-01-01
OBJECTIVES: The aims of the present study were to (i) cross-culturally adapt a Danish consensus version of the 10-item Perceived Stress Scale (PSS-10) and (ii) evaluate its psychometric properties in terms of agreement, reliability, validity, responsiveness, and interpretability among patients...
Szabo, Marianna
2010-01-01
This study explored the factor structure of the short form of the Depression Anxiety Stress Scales (DASS-21; Lovibond & Lovibond, 1995b) in a young adolescent sample. A group of 484 high school students ("Mean" age = 13.62 years, Min = 11.83, Max = 15.67 years, 52 % boys) completed the DASS-21. Several models were tested using Confirmatory Factor…
Validity of 42-Item Mooney Problem Check List Scale for Counseling.
Tryon, Georgiana Shick
Studies employing the Mooney Problem Check List (MPCL) have found that counseling center clients indicate more problems on the MPCL than nonclients. Domino and DeGroote identified 42 MPCL items concerned with self-satisfaction and a need for social contacts which further differentiated counseling seekers from nonseekers. In order to further…
Carvajal, Scott C.; Rosales, Cecilia; Rubio-Goldsmith, Raquel; Sabo, Samantha; Ingram, Maia; McClelland, Debra Jean; Redondo, Floribella; Torres, Emma; Romero, Andrea J.; Oleary, Anna Ochoa; Sanchez, Zoila; de Zapien, Jill Guernsey
2015-01-01
Background Understanding contemporary socio-cultural stressors may assist educational, clinical and policy-level health promotion efforts. This study presents descriptive findings on a new measure, the Border Community & Immigration Stress Scale (BCISS). Methods The data were from two community surveys as part of community based participatory projects conducted in the Southwestern US border region. This scale includes stressful experiences reflected in extant measures, with new items reflecting heightened local migration pressures and health care barriers. Results Stressors representing each main domain, including novel ones, were reported with frequency and at high intensity in the predominantly Mexican-descent samples. Total stress was also significantly associated with mental and physical health indicators. Discussion The study suggests particularly high health burdens tied to the experience of stressors in the US border region. Further, many of the stressors are also likely relevant for other communities within developed nations also experiencing high levels of migration. PMID:22430894
Vasconcelos-Raposo, José; Fernandes, Helder Miguel; Teixeira, Carla M
2013-01-01
The purpose of the present study was to assess the factor structure and reliability of the Depression, Anxiety and Stress Scales (DASS-21) in a large Portuguese community sample. Participants were 1020 adults (585 women and 435 men), with a mean age of 36.74 (SD = 11.90) years. All scales revealed good reliability, with Cronbach's alpha values between .80 (anxiety) and .84 (depression). The internal consistency of the total score was .92. Confirmatory factor analysis revealed that the best-fitting model (*CFI = .940, *RMSEA = .038) consisted of a latent component of general psychological distress (or negative affectivity) plus orthogonal depression, anxiety and stress factors. The Portuguese version of the DASS-21 showed good psychometric properties (factorial validity and reliability) and thus can be used as a reliable and valid instrument for measuring depression, anxiety and stress symptoms.
The Bahasa Melayu version of the Nursing Stress Scale among nurses: a reliability study in Malaysia.
Rosnawati, Muhamad Robat; Moe, Htay; Masilamani, Retneswari; Darus, A
2010-10-01
The Nursing Stress Scale (NSS) has been shown to be a valid and reliable instrument to assess occupational stressors among nurses. The NSS, which was previously used in the English version, was translated and back-translated into Bahasa Melayu. This study was conducted to assess the reliability of the Bahasa Melayu version of the NSS among nurses for future studies in this country. The reliability of the NSS was assessed after its readministration to 30 nurses with a 2-week interval. The Spearman coefficient was calculated to assess its stability. The internal consistency was measured through 4 measures: Cronbach's α, Spearman-Brown, Guttman split-half, and standardized item α coefficients. The total response rate was 70%. Test-retest reliability showed remarkable stability (Spearman's ρ exceeded .70). All 4 measures of internal consistency among items indicated a satisfactory level (coefficients in the range of .68 to .87). In conclusion, the Bahasa Melayu version of the NSS is a reliable and useful instrument for measuring the possible stressors at the workplace among nurses.
Robbins, Neil E.
2016-01-01
Water is the most limiting resource on land for plant growth, and its uptake by plants is affected by many abiotic stresses, such as salinity, cold, heat, and drought. While much research has focused on exploring the molecular mechanisms underlying the cellular signaling events governing water-stress responses, it is also important to consider the role organismal structure plays as a context for such responses. The regulation of growth in plants occurs at two spatial scales: the cell and the organ. In this review, we focus on how the regulation of growth at these different spatial scales enables plants to acclimate to water-deficit stress. The cell wall is discussed with respect to how the physical properties of this structure affect water loss and how regulatory mechanisms that affect wall extensibility maintain growth under water deficit. At a higher spatial scale, the architecture of the root system represents a highly dynamic physical network that facilitates access of the plant to a heterogeneous distribution of water in soil. We discuss the role differential growth plays in shaping the structure of this system and the physiological implications of such changes. PMID:27503468
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... sudden negative change, such as losing a job, divorce, or illness Traumatic stress, which happens when you ... stress, so you can avoid more serious health effects. NIH: National Institute of Mental Health
An efficient regularization method for a large scale ill-posed geothermal problem
Berntsson, Fredrik; Lin, Chen; Xu, Tao; Wokiyi, Dennis
2017-08-01
The inverse geothermal problem consists of estimating the temperature distribution below the earth's surface using measurements on the surface. The problem is important since temperature governs a variety of geologic processes, including the generation of magmas and the deformation style of rocks. Since the thermal properties of rocks depend strongly on temperature the problem is non-linear. The problem is formulated as an ill-posed operator equation, where the righthand side is the heat-flux at the surface level. Since the problem is ill-posed regularization is needed. In this study we demonstrate that Tikhonov regularization can be implemented efficiently for solving the operator equation. The algorithm is based on having a code for solving a well-posed problem related to the above mentioned operator. The algorithm is designed in such a way that it can deal with both 2 D and 3 D calculations. Numerical results, for 2 D domains, show that the algorithm works well and the inverse problem can be solved accurately with a realistic noise level in the surface data.
Nelson Valdivia
Full Text Available In rocky intertidal habitats, the pronounced increase in environmental stress from low to high elevations greatly affects community structure, that is, the combined measure of species identity and their relative abundance. Recent studies have shown that ecological variation also occurs along the coastline at a variety of spatial scales. Little is known, however, on how vertical variation compares with horizontal variation measured at increasing spatial scales (in terms of sampling interval. Because broad-scale processes can generate geographical patterns in community structure, we tested the hypothesis that vertical ecological variation is higher than fine-scale horizontal variation but lower than broad-scale horizontal variation. To test this prediction, we compared the variation in community structure across intertidal elevations on rocky shores of Helgoland Island with independent estimates of horizontal variation measured at the scale of patches (quadrats separated by 10s of cm, sites (quadrats separated by a few m, and shores (quadrats separated by 100s to 1000s of m. The multivariate analyses done on community structure supported our prediction. Specifically, vertical variation was significantly higher than patch- and site-scale horizontal variation but lower than shore-scale horizontal variation. Similar patterns were found for the variation in abundance of foundation taxa such as Fucus spp. and Mastocarpus stellatus, suggesting that the effects of these canopy-forming algae, known to function as ecosystem engineers, may explain part of the observed variability in community structure. Our findings suggest that broad-scale processes affecting species performance increase ecological variability relative to the pervasive fine-scale patchiness already described for marine coasts and the well known variation caused by vertical stress gradients. Our results also indicate that experimental research aiming to understand community structure on
The Development, Evaluation, and Validation of a Financial Stress Scale for Undergraduate Students
Northern, Jebediah J.; O'Brien, William H.; Goetz, Paul W.
2010-01-01
Financial stress is commonly experienced among college students and is associated with adverse academic, mental health, and physical health outcomes. Surprisingly, no validated measures of financial stress have been developed for undergraduate populations. The present study was conducted to generate and evaluate a measure of financial stress for…
Evaluation of residual stresses in laser clad coating at the micrometer scale
Furár, I.; Ocelík, V.; De Hosson, J.T.M.
2011-01-01
Residual stresses may have beneficial or detrimental effects to the materials properties and therefore precise knowledge and control of residual stresses are of high practical relevance. For the stress-relaxation measurement at a micro level we explored the slit milling (crack compliance) method usi
Moment rate scaling for earthquakes 3.3 ≤ M ≤ 5.3 with implications for stress drop
Archuleta, Ralph J.; Ji, Chen
2016-12-01
We have determined a scalable apparent moment rate function (aMRF) that correctly predicts the peak ground acceleration (PGA), peak ground velocity (PGV), local magnitude, and the ratio of PGA/PGV for earthquakes 3.3 ≤ M ≤ 5.3. Using the NGA-West2 database for 3.0 ≤ M ≤ 7.7, we find a break in scaling of LogPGA and LogPGV versus M around M 5.3 with nearly linear scaling for LogPGA and LogPGV for 3.3 ≤ M ≤ 5.3. Temporal parameters tp and td—related to rise time and total duration—control the aMRF. Both scale with seismic moment. The Fourier amplitude spectrum of the aMRF has two corners between which the spectrum decays f- 1. Significant attenuation along the raypath results in a Brune-like spectrum with one corner fC. Assuming that fC ≅ 1/td, the aMRF predicts non-self-similar scaling M0∝fC3.3 and weak stress drop scaling Δσ∝M00.091. This aMRF can explain why stress drop is different from the stress parameter used to predict high-frequency ground motion.
Melatonin and sleep effects on health, behavior problems and parenting stress
van Maanen, A.; Meijer, A.M.; Smits, M.G.; Oort, F.J.
2011-01-01
In children with sleep-onset insomnia and delayed dim-light melatonin onset, melatonin treatment not only improves sleep but also health, behavior and parenting stress. The aim of the present study was to see whether the latter effects are dependent on the direct effects on sleep. Data come from 41
Posttraumatic Stress and Problem Drinking at the Transition Out of College.
Read, Jennifer P; Radomski, Sharon; Wardell, Jeffrey D
2017-04-04
The objective of the present study was to examine how symptoms of posttraumatic stress disorder (PTSD) may confer drinking risk as students with trauma histories complete college and move toward independent adulthood. Students (N = 283) completed assessments of trauma, posttraumatic stress, and alcohol use and consequences at four time points during the year following their fourth year of college. Some students had transitioned out of the college environment, whereas others had not. We examined how transition status moderated within-person associations between changes in PTSD and corresponding changes in alcohol outcomes over time. Using multilevel modeling, we examined differences in within-person PTSD-alcohol associations comparing students who were (1) continuing as fifth-year seniors, (2) graduated and pursuing graduate education, and (3) graduated and left the university setting. Alcohol use and consequences tended to decline on average from the fourth to fifth year post-matriculation. Yet, within-person increases in posttraumatic stress symptomatology across the fifth year were associated with greater alcohol consequences, but only for those students who had left the university setting. These data suggest that the transition out of college may be an important developmental context that is associated with increased vulnerability for negative consequences from stress-related drinking. Findings may have important implications for campus-based prevention efforts geared toward the facilitation of a successful transition into independent adulthood.
Melatonin and sleep effects on health, behavior problems and parenting stress
van Maanen, A.; Meijer, A.M.; Smits, M.G.; Oort, F.J.
2011-01-01
In children with sleep-onset insomnia and delayed dim-light melatonin onset, melatonin treatment not only improves sleep but also health, behavior and parenting stress. The aim of the present study was to see whether the latter effects are dependent on the direct effects on sleep. Data come from 41
Adaptive Skills, Behavior Problems, and Parenting Stress in Mothers of Boys with Fragile X Syndrome
Sarimski, Klaus
2010-01-01
The relationship of temperament, atypical behaviors, and adaptive behavior of young boys with Fragile X syndrome on mothers' parenting stress was analyzed. Twenty-six boys with Fragile X syndrome (30-88 months of age) participated. The overall development of the participants was significantly delayed with a specific profile of adaptive behaviors…
Entropy Stress and Scaling of Vital Organs over Life Span Based on Allometric Laws
Carlos Silva
2012-12-01
Full Text Available Abstract: Past theories on total lifetime energy expenditures and entropy generation in biological systems (BS dealt with whole systems, but the recent literature suggests that the total metabolic rate of a BS,q̇body (W is a sum of product of specific metabolic rate q̇k,m (W/kg of organ k of each vital life organ, k {k = brain, heart, kidney and liver, or abbreviated as BHKL, and rest of the organ mass (R} and mass of each organ k (mk. Using this hypothesis, Kleiber’s law on metabolic rate of BS (q̇body for animals of different sizes was validated. In this work, a similar procedure is adopted in estimating total entropy generation rate of whole human body (σ̇body, W/K as a sum of product of specific entropy generation rate for each organ, σ̇k,m (W/{K kg of organ k·} and the organ mass at any given age (t. Further integrating over life span for each organ (tlife, the lifetime specific entropy generated by organ k, σk,m,life (J of organ k/ {K kg organ k} is calculated. Then lifetime entropy generation of unit body mass, σbody,M,life (J/{K kg body mass·} is calculated as a sum of the corresponding values contributed by all vital organs to unit body mass and verified with previously published literature. The higher the σk,m,life , the higher the entropy stress level (which is a measure of energy released by unit organ mass of k as heat and the irreversibility within the organ, resulting in faster degradation of organ and the consequent health problems for the whole BS. In order to estimate σ̇k (W/K of organ k, data on energy release rate (q̇ is needed over lifetime for each organ. While the Adequate Macronutrients Distribution Range (AMDR/Adequate Intake (AI publication can be used in estimating the energy intake of whole body vs. age for the human body, the energy expenditure data is not available at organ level. Hence the σk,m,life was computed using existing allometric laws developed for the metabolism of the organs, the
High scale parity invariance as a solution to the SUSY CP problem and an explanation of small '/*
R N Mohapatra
2000-07-01
It is shown that if the supersymmetric Standard Model (MSSM) emerges as the low energy limit of a high scale left–right symmetric gauge structure, the number of uncontrollable CP violating phases of MSSM are drastically reduced. In particular it guarantees the vanishing of the dangerous phases that were at the root of the so called SUSY CP problem. Such a symmetric gauge structure is independently motivated by the smallness of neutrino masses that arise via seesaw mechanism automatic in the theory. The minimal version of this theory also provides an explanation of the smallness of '/ as a consequence of the high scale parity invariance.
Fisher, Philip A; Gunnar, Megan R; Dozier, Mary; Bruce, Jacqueline; Pears, Katherine C
2006-12-01
Young children in foster care are exposed to high levels of stress. These experiences place foster children at risk for poor social, academic, and mental heath outcomes. The role of adverse events in stimulating neurobiological stress responses presumably plays a role in shaping neural systems that contribute to these problems. Systematic and developmentally well-timed interventions might have the potential to change developmental trajectories and promote resilience. Moreover, understanding how specific dimensions of early adversity affect underlying stress response systems and how alterations in these systems are related to later psychosocial outcomes might facilitate more precise and targeted interventions. Data are drawn from two ongoing randomized trials involving foster infants/toddlers and preschoolers. Consistent with prior animal models of early adversity, these studies have shown that early adversity-particularly neglect, younger age at first foster placement, and higher number of placements-is associated with altered hypothalamic-pituitary-adrenal (HPA) axis function. The interventions under investigation have produced evidence that it is possible to impact many areas that have been negatively affected by early stress, including HPA axis activity, behavior, and attachment to caregivers.
Stress generation in thermally grown oxide films. [oxide scale spalling from superalloy substrates
Kumnick, A. J.; Ebert, L. J.
1981-01-01
A three dimensional finite element analysis was conducted, using the ANSYS computer program, of the stress state in a thin oxide film thermally formed on a rectangular piece of NiCrAl alloy. The analytical results indicate a very high compressive stress in the lateral directions of the film (approximately 6200 MPa), and tensile stresses in the metal substrate that ranged from essentially zero to about 55 MPa. It was found further that the intensity of the analytically determined average stresses could be approximated reasonably well by the modification of an equation developed previously by Oxx for stresses induced into bodies by thermal gradients.
H Dattu; M Subbiah
2015-09-01
We consider the linear stability problem of inviscid, incompressible swirling flows with radius-dependent density with respect to two-dimensional disturbances. Some results of Miles on the parallel flow stability theory are extended to the swirling flow stability theory. In particular, series solutions for the stability equation for swirling flows are obtained and these solutions are used in the study of the variation of the Reynolds stress. For singular neutral modes it is shown that the Reynolds stress varies like the inverse square of the radial distance in agreement with the homogeneous flow result of Maslowe & Nigam. It is also proved that singular neutral modes do not exist whenever the value of the Richardson number at the critical layer exceeds one quarter.
Donarelli, Zaira; Gullo, Salvatore; Lo Coco, Gianluca; Marino, Angelo; Scaglione, Piero; Volpes, Aldo; Allegra, Adolfo
2015-01-01
The factor structure of the Fertility Problem Inventory (FPI) and its invariance across gender were examined in Italian couples undergoing infertility treatment. About 1000 subjects (both partners of 500 couples) completed two questionnaires prior to commencing infertility treatment at a private Clinic in Palermo, Italy. Confirmatory Factor Analysis demonstrated that the original factor structure of the FPI was partially confirmed. Two correlated factors (Infertility Life Domains and Importance of Parenthood) were obtained via a post hoc Exploratory Factor Analysis. Finally, the invariance of this factor structure across gender was confirmed. The study supported the relevance of two interrelated factors specific to infertility stress which could help clinicians to focus on the core infertility-related stress domains of infertile couples.
Lin, Jaw-Ren; Hung, Chi-Ren; Lu, Rong-Fang [Nanya Institute of Technology, Jhongli, Taiwan (China). Dept. of Mechanical Engineering; Chu, Li-Ming [I-Shou Univ., Kaohsiung, Taiwan (China). Dept. of Mechanical and Automation Engineering
2011-08-15
According to the experimental work of C. Barus in Am. J. Sci. 45, 87 (1893), the dependency of liquid viscosity on pressure is exponential. Therefore, we extend the study of squeeze film problems of long partial journal bearings for Stokes non-Newtonian couple stress fluids by considering the pressure-dependent viscosity in the present paper. Through a small perturbation technique, we derive a first-order closed-form solution for the film pressure, the load capacity, and the response time of partial-bearing squeeze films. It is also found that the non-Newtonian couple-stress partial bearings with pressure-dependent viscosity provide better squeeze-film characteristics than those of the bearing with constant-viscosity situation. (orig.)
Lin, Jaw-Ren; Chu, Li-Ming; Hung, Chi-Ren; Lu, Rong-Fang
2011-09-01
According to the experimental work of C. Barus in Am. J. Sci. 45, 87 (1893) [1], the dependency of liquid viscosity on pressure is exponential. Therefore, we extend the study of squeeze film problems of long partial journal bearings for Stokes non-Newtonian couple stress fluids by considering the pressure-dependent viscosity in the present paper. Through a small perturbation technique, we derive a first-order closed-form solution for the film pressure, the load capacity, and the response time of partial-bearing squeeze films. It is also found that the non-Newtonian couple-stress partial bearings with pressure-dependent viscosity provide better squeeze-film characteristics than those of the bearing with constant-viscosity situation.
Sahraoui, F.
2014-12-01
The ESA/Cluster and the NASA/Themis missions have allowed for making a significant progress in understanding the problem of turbulence and energy dissipation at sub-ion and electron scales in the solar wind. Yet, several key questions cannot be addressed by these missions or by the upcoming ones (e.g., MMS, Solar Orbiter) because of instrumental limitations. We will discuss some of these scientific questions and instrumental limitations, then present a new mission concept, TWINS, designed to solve the problem of turbulence and energy dissipation at electron scales in the solar wind. This dual-spacecraft mission is based on the TOR concept, a single spacecraft mission proposed to the ESA/S1-class call in 2012. TWINS is one the mission concepts that is currently being discussed within the community in view of proposing it to the upcoming ESA/M4 call expected in 2014.
Ledgerwood, David M; Milosevic, Aleks
2015-06-01
Problem and pathological gamblers (PPGs) are more likely than the general population to experience co-occurring psychiatric problems. However, the problem gambling literature has largely overlooked the importance of trauma and post-traumatic stress disorder (PTSD) as a prevalent co-occurring condition among PPGs. This study examined clinical differences between PPGs with and without a history of co-occurring PTSD. Lifetime PPGs (N = 150) recruited from community sources completed clinical assessments including measures of problem gambling severity, co-occurring psychiatric conditions, gambling motivations and personality traits. Over 19% of the participants met criteria for a lifetime diagnosis of PTSD. Those presenting with PTSD histories were more likely to be women, and were more likely to have lifetime substance use disorder (abuse and/or dependence) and substance dependence, lifetime major depressive disorder, current dysthymic disorder, and lifetime and current anxiety disorder. Those with lifetime PTSD also were more likely to use gambling as a way to cope with negative emotions and experienced greater negative emotionality. Few PPGs (16%) had ever sought treatment for their gambling problems. PTSD is a prevalent condition among individuals with lifetime PPG recruited from the community, and is associated with greater psychiatric co-morbidity among these populations. More research is needed to further understand the relationship between gambling and trauma, and better outreach is needed to encourage these individuals to seek treatment.
Open Problems in Network-aware Data Management in Exa-scale Computing and Terabit Networking Era
Balman, Mehmet; Byna, Surendra
2011-12-06
Accessing and managing large amounts of data is a great challenge in collaborative computing environments where resources and users are geographically distributed. Recent advances in network technology led to next-generation high-performance networks, allowing high-bandwidth connectivity. Efficient use of the network infrastructure is necessary in order to address the increasing data and compute requirements of large-scale applications. We discuss several open problems, evaluate emerging trends, and articulate our perspectives in network-aware data management.
Zohsel, K; Bianchi, V; Mascheretti, S; Hohm, E; Schmidt, M H; Esser, G; Brandeis, D; Banaschewski, T; Nobile, M; Laucht, M
2015-11-01
Attention problems affect a substantial number of children and adolescents and are predictive of academic underachievement and lower global adaptive functioning. Considerable variability has been observed with regard to the individual development of attention problems over time. In particular, the period of adolescence is characterized by substantial maturation of executive functioning including attentional processing, with the influence of genetic and environmental factors on individual trajectories not yet well understood. In the present investigation, we evaluated whether the monoamine oxidase A functional promoter polymorphism, MAOA-LPR, plays a role in determining continuity of parent-rated attention problems during adolescence. At the same time, a potential effect of severe life events (SLEs) was taken into account. A multi-group path analysis was used in a sample of 234 adolescents (149 males, 85 females) who took part in an epidemiological cohort study at the ages of 11 and 15 years. Attention problems during early adolescence were found to be a strong predictor of attention problems in middle adolescence. However, in carriers of the MAOA-LPR low-activity variant (MAOA-L), stability was found to be significantly higher than in carriers of the high-activity variant (MAOA-H). Additionally, only in MAOA-L carriers did SLEs during adolescence significantly impact on attention problems at the age of 15 years, implying a possible gene × environment interaction. To conclude, we found evidence that attention problems during adolescence in carriers of the MAOA-L allele are particularly stable and malleable to life stressors. The present results underline the usefulness of applying a more dynamic GxE perspective. © 2015 John Wiley & Sons Ltd and International Behavioural and Neural Genetics Society.
Lopez-Fernandez, Olatz; Freixa-Blanxart, Montserrat; Honrubia-Serrano, Maria Luisa
2013-02-01
Many researchers and professionals have reported nonsubstance addiction to online entertainments in adolescents. However, very few scales have been designed to assess problem Internet use in this population, in spite of their high exposure and obvious vulnerability. The aim of this study was to review the currently available scales for assessing problematic Internet use and to validate a new scale of this kind for use, specifically in this age group, the Problematic Internet Entertainment Use Scale for Adolescents. The research was carried out in Spain in a gender-balanced sample of 1131 high school students aged between 12 and 18 years. Psychometric analyses showed the scale to be unidimensional, with excellent internal consistency (Cronbach's alpha of 0.92), good construct validity, and positive associations with alternative measures of maladaptive Internet use. This self-administered scale can rapidly measure the presence of symptoms of behavioral addiction to online videogames and social networking sites, as well as their degree of severity. The results estimate the prevalence of this problematic behavior in Spanish adolescents to be around 5 percent.
Emerging solution of large-scale unit commitment problem by Stochastic Priority List
Senjyu, Tomonobu; Miyagi, Tsukasa; Saber, Ahmed Yousuf; Urasaki, Naomitsu [Faculty of Engineering, University of the Ryukyus, 1 Senbaru Nishihara-cho Nakagami, Okinawa 903-0213 (Japan); Funabashi, Toshihisa [Meidensha Corporation Riverside Building 36-2, Nihonbashi Hokozakicho, Chuo-ku, Tokyo 103-8515 (Japan)
2006-03-15
This paper presents a new approach for unit commitment problem using Stochastic Priority List method. In this method, rapidly some initial unit commitment schedules are generated by Priority List method and priority based stochastic window system. Excess units are added with system dependent probability distribution to avoid overlooking a desired solution during repeated search. Constraints are not considered in this stage. Then schedules are modified gradually using the problem specific heuristics to fulfill constraints. To reduce calculations, heuristics are applied only to the solutions, which can be expected to improve. Besides, sign vector is introduced to reduce economic load dispatch (ELD) overhead recalculations. This process is repeated for optimal solution. The proposed method is tested using the reported problem data set. Simulation results for the systems up to 100-unit are compared to previous reported results. Numerical results show an improvement in solution cost and time compared to the results obtained from Genetic Algorithm and others. (author)
Lidorikis, Elefterios; Bachlechner, Martina E.; Kalia, Rajiv K.; Nakano, Aiichiro; Vashishta, Priya; Voyiadjis, George Z.
2001-08-20
A hybrid molecular-dynamics (MD) and finite-element simulation approach is used to study stress distributions in silicon/silicon-nitride nanopixels. The hybrid approach provides atomistic description near the interface and continuum description deep into the substrate, increasing the accessible length scales and greatly reducing the computational cost. The results of the hybrid simulation are in good agreement with full multimillion-atom MD simulations: atomic structures at the lattice-mismatched interface between amorphous silicon nitride and silicon induce inhomogeneous stress patterns in the substrate that cannot be reproduced by a continuum approach alone.
Buijze, Loes; Guo, Yanhuang; Niemeijer, André R.; Ma, Shengli; Spiers, Christopher J.
2017-04-01
Faults in the upper crust cross-cut many different lithologies, which cause the composition of the fault rocks to vary. Each different fault rock segment may have specific mechanical properties, e.g. there may be stronger and weaker segments, and segments prone to unstable slip or creeping. This leads to heterogeneous deformation and stresses along such faults, and a heterogeneous distribution of seismic events. We address the influence of fault variability on stress, deformation, and seismicity using a combination of scaled laboratory fault and numerical modeling. A vertical fault was created along the diagonal of a 30 x 20 x 5 cm block of PMMA, along which a 2 mm thick gouge layer was deposited. Gouge materials of different characteristics were used to create various segments along the fault; quartz (average strength, stable sliding), kaolinite (weak, stable sliding), and gypsum (average strength, unstable sliding). The sample assembly was placed in a horizontal biaxial deformation apparatus, and shear displacement was enforced along the vertical fault. Multiple observations were made: 1) Acoustic emissions were continuously recorded at 3 MHz to observe the occurrence of stick-slips (micro-seismicity), 2) Photo-elastic effects (indicative of the differential stress) were recorded in the transparent set of PMMA wall-rocks using a high-speed camera, and 3) particle tracking was conducted on a speckle painted set of PMMA wall-rocks to study the deformation in the wall-rocks flanking the fault. All three observation methods show how the heterogeneous fault gouge exerts a strong control on the fault behavior. For example, a strong, unstable segment of gypsum flanked by two weaker kaolinite segments show strong stress concentrations develop near the edges of the strong segment, with at the same time most of acoustic emissions being located at the edge of this strong segment. The measurements of differential stress, strain and acoustic emissions provide a strong means
Solving Large-Scale QAP Problems in Parallel with the Search
Clausen, Jens; Brüngger, A.; Marzetta, A.
1998-01-01
Program libraries are one tool to make the cooperation between specialists from various fields successful: the separation of application-specific knowledge from application-independent tasks ensures portability, maintenance, extensibility, and flexibility. The current paper demonstrates the success...... in combining problem-specific knowledge for the quadratic assignment problem (QAP) with the raw computing power offered by contemporary parallel hardware by using the library of parallel search algorithms ZRAM. Solutions of previously unsolved large standard test-instances of the QAP are presented....
无
2007-01-01
Let G = (V, E) be a complete undirected graph with vertex set V, edge set E, and edge weights I(e)satisfying the triangle inequality. The vertex set V is partitioned into clusters V1, V2 Vk. The clustered traveling salesman problem (CTSP) seeks to compute the shortest Hamiltonian tour that visits all the vertices, in which the vertices of each cluster are visited consecutively. A two-level genetic algorithm (TLGA) was developed for the problem, which favors neither intra-cluster paths nor inter-cluster paths, thus realized integrated evolutionary optimization for both levels of the CTSP. Results show that the algorithm is more effective than known algorithms. A large-scale traveling salesman problem (TSP) can be converted into a CTSP by clustering so that it can then be solved by the algorithm. Test results demonstrate that the clustering TLGA for large TSPs is more effective and efficient than the classical genetic algorithm.
Debra L. Rezendes
2011-01-01
Full Text Available Parents of children with autism spectrum disorders (ASDs have been shown to experience increases in stress, depression, and anxiety, which are also associated with child behavior problems related to ASDs. Literature-examining potential mechanisms that underlie the relationship of child behavior problems and parental anxiety/depression in this population are scarce. The current study sought to examine the roles of parenting stress and parenting self-efficacy as mediators between child behavior problems and parental anxiety/depression. Using a sample of 134 mothers, these potential mediators were tested. Hypotheses were supported, indicating that parenting stress mediated the relationship between child behavior problems and decreased parenting self-efficacy, and decreased parenting self-efficacy in turn partially mediated the relationship between parenting stress and increased depression/anxiety.
Limin, Chen; Van Dooren, Wim; Verschaffel, Lieven
2013-01-01
The goal of the present study is to investigate the relationship between pupils' problem posing and problem solving abilities, their beliefs about problem posing and problem solving, and their general mathematics abilities, in a Chinese context. Five instruments, i.e., a problem posing test, a problem solving test, a problem posing…
Giuseppe CAFORIO
2014-10-01
Full Text Available This article deals with the problems of anxiety, stress and psychological discomfort that can affect soldiers sent on asymmetric warfare operations. It is based on secondary analysis of the data of two important field researches whose results have recently (2013 been published. Although the two researches adopted different methodologies, the testimonies are fully comparable and show that soldiers from different countries and cultures display common or similar reactions when they are placed in the stress conditions that the asymmetric environment involves. The approach of the paper is drawn up in such a way as to make the reader a participating observer of the reality of such missions. It is therefore centered on the personal testimonies of the soldiers interviewed in the two researches, testimonies reported just as they are, in their simplicity and, often, drama, with comments by the author kept to a minimum in order to give readers ample opportunity to evaluate and interpret the reported texts on their own. The research data, drawn from the declarations of those directly concerned, reveal the existence of a problem of psychological distress resulting from deployment in asymmetric warfare situations that is in part different in the causes of the problems resulting from deployment in traditional combat and affects percentages of participating soldiers that are not high but definitely significant. The highest incidence appears to be constituted by problems relating to reintegration into normal social and working life upon returning from the mission. This is followed in percentage terms by anxiety situations relating to life far from the family, due in large part to a sense of powerlessness for the scant possibility of managing family situations that may have cropped up or already existed beforehand.
Repeat prescribing: scale, problems and quality management in ambulatory care patients.
Smet, P.A.G.M. de; Dautzenberg, M.
2004-01-01
The reported scale of repeat prescriptions ranges from 29% to 75% of all items prescribed, depending on the definition of repeat prescribing and other variables. It is likely that a substantial part of repeat prescribing by general practitioners (GPs) occurs without direct doctor-patient contact.
Time-scale decomposition of an optimal control problem in greenhouse climate management
Henten, van E.; Bontsema, J.
2009-01-01
Based on differences in dynamic response times in the crop production process, a hierarchical decomposition of greenhouse climate management is proposed. To a large extent the proposed decomposition builds on the time-scale decomposition of singularly perturbed systems commonly found in the
Tran Thach Duc
2013-01-01
Full Text Available Abstract Background Depression and anxiety are recognised increasingly as serious public health problems among women in low- and lower-middle income countries. The aim of this study was to validate the 21-item Depression Anxiety and Stress Scale (DASS21 for use in screening for these common mental disorders among rural women with young children in the North of Vietnam. Methods The DASS-21 was translated from English to Vietnamese, culturally verified, back-translated and administered to women who also completed, separately, a psychiatrist-administered Structured Clinical Interview for DSM IV Axis 1 diagnoses of depressive and anxiety disorders. The sample was a community-based representative cohort of adult women with young children living in Ha Nam Province in northern Viet Nam. Cronbach’s alpha, Exploratory Factor Analyses (EFA and Receiver Operating Characteristic (ROC analyses were performed to identify the psychometric properties of the Depression, Anxiety, and Stress subscales and the overall scale. Results Complete data were available for 221 women. The internal consistency (Cronbach’s alpha of each sub-scale and the overall scale were high, ranging from 0.70 for the Stress subscale to 0.88 for the overall scale, but EFA indicated that the 21 items all loaded on one factor. Scores on each of the three sub-scales, and the combinations of two or three of them were able to detect the common mental disorders of depression and anxiety in women with a sensitivity of 79.1% and a specificity of 77.0% at the optimal cut off of >33. However, they did not distinguish between those experiencing only depression or only anxiety. Conclusions The total score of the 21 items of the DASS21-Vietnamese validation appears to be comprehensible and sensitive to detecting common mental disorders in women with young children in primary health care in rural northern Vietnam and therefore might also be useful to screen for these conditions in other resource
De Hoop, A.T.; Abubakar, A.; Habashy, T.M.
2009-01-01
The contrast-source stress-velocity integral-equation formulation of three-dimensional time-domain elastodynamic scattering problems is discussed. A novel feature of the formulation is a tensor partitioning of the relevant dynamic stress and the contrast source volume density of deformation rate. Th
La Valle, Chelsea
2015-01-01
Parents of children with significant externalizing and internalizing behavioral problems habitually report greater parenting stress compared to parents of children without these challenges. One avenue to alleviate parenting stress and ameliorate youth outcomes is youth mentoring, which includes a supportive adult paired with a child with the…
Weiss, Nicole H.; Duke, Aaron A.; Overstreet, Nicole M.; Swan, Suzanne C.; Sullivan, Tami P.
2017-01-01
A dearth of literature has examined the consequences of women’s use of aggression in intimate relationships. Women’s use of aggression against their intimate partners, regardless of their motivation (e.g., self-defense, retaliation), may elicit shame. Shame, in turn, may contribute to the maintenance and/or exacerbation of posttraumatic stress disorder (PTSD) symptoms, which are commonly experienced in this population. Further, emerging research suggests that emotionally-avoidant coping strategies, such as substance use, may strengthen the relation between shame and PTSD symptoms. The goal of the present study was to examine whether women’s shame concerning their use of intimate partner aggression is associated with their PTSD symptoms, and whether drug and alcohol use problems moderate this association. Participants were 369 community women who had used and been victimized by physical aggression in an intimate relationship with a male partner in the past six months. The intimate partner aggression-related shame × drug (but not alcohol) use problems interaction on PTSD symptom severity was significant. Analysis of simple slopes revealed that women’s intimate partner aggression-related shame was positively associated with their PTSD symptoms when drug use problems were high, but not when drug use problems were low. Findings have implications for the potential utility of PTSD treatments targeting a reduction in shame and maladaptive shame regulation strategies (i.e., drug use) in this population. PMID:26699821
Subtrochanteric stress fractures in patients on oral bisphosphonate therapy: an emerging problem.
Murphy, Colin G
2012-01-31
The emergence of a new variant of subtrochanteric stress fractures of the femur, affecting patients on oral bisphosphonate therapy, has only recently been described. This fracture is often preceded by pain and distinctive radiographic changes (lateral cortical thickening), and associated with a characteristic fracture pattern (transverse fracture line and medial cortical spike). A retrospective review (2007-2009) was carried out for patients who were taking oral bisphosphonates and who sustained a subtrochanteric fracture after a low velocity injury. Eleven fractures were found in 10 patients matching the inclusion criteria outlined. All were females, and taking bisphosphonates for a mean of 43 years. Five of the 10 patients mentioned prodromal symptoms, for an average of 9.4 months before the fracture. Although all fractures were deemed low velocity, 5 of 11 were even atraumatic. Two patients had previously sustained contralateral subtrochanteric fractures. Plain radiographs of two patients showed lateral cortical thickening on the contralateral unfractured femur; the bisphosphonate therapy was stopped and close surveillance was started. Patients taking oral bisphosphonates may be at risk of a new variant of stress fracture of the proximal femur. Awareness of the symptoms is the key to ensure that appropriate investigations are undertaken.
Subtrochanteric stress fractures in patients on oral bisphosphonate therapy: an emerging problem.
Murphy, Colin G; O'Flanagan, Shay; Keogh, Peter; Kenny, Patrick
2011-10-01
The emergence of a new variant of subtrochanteric stress fractures of the femur, affecting patients on oral bisphosphonate therapy, has only recently been described. This fracture is often preceded by pain and distinctive radiographic changes (lateral cortical thickening), and associated with a characteristic fracture pattern (transverse fracture line and medial cortical spike). A retrospective review (2007-2009) was carried out for patients who were taking oral bisphosphonates and who sustained a subtrochanteric fracture after a low velocity injury. Eleven fractures were found in 10 patients matching the inclusion criteria outlined. All were females, and taking bisphosphonates for a mean of 43 years. Five of the 10 patients mentioned prodromal symptoms, for an average of 9.4 months before the fracture. Although all fractures were deemed low velocity, 5 of 11 were even atraumatic. Two patients had previously sustained contralateral subtrochanteric fractures. Plain radiographs of two patients showed lateral cortical thickening on the contralateral unfractured femur; the bisphosphonate therapy was stopped and close surveillance was started. Patients taking oral bisphosphonates may be at risk of a new variant of stress fracture of the proximal femur. Awareness of the symptoms is the key to ensure that appropriate investigations are undertaken.
Kaipainen, Kirsikka; Lappalainen, Raimo; Hoffrén, Henna; Myllymäki, Tero; Kinnunen, Marja-Liisa; Mattila, Elina; Happonen, Antti P; Rusko, Heikki; Korhonen, Ilkka
2013-01-01
Background Work-related stress is a significant problem for both people and organizations. It may lead to mental illnesses such as anxiety and depression, resulting in increased work absences and disabilities. Scalable interventions to prevent and manage harmful stress can be delivered with the help of technology tools to support self-observations and skills training. Objective The aim of this study was to assess the feasibility of the P4Well intervention in treatment of stress-related psychological problems. P4Well is a novel intervention which combines modern psychotherapy (the cognitive behavioral therapy and the acceptance and commitment therapy) with personal health technologies to deliver the intervention via multiple channels, includinggroup meetings, Internet/Web portal, mobile phone applications, and personal monitoring devices. Methods This pilot study design was a small-scale randomized controlled trial that compared the P4Well intervention with a waiting list control group. In addition to personal health technologies for self-assessment, the intervention consisted of 3 psychologist-assisted group meetings. Self-assessed psychological measures through questionnaires were collected offline pre- and post-intervention, and 6 months after the intervention for the intervention group. Acceptance and usage of technology tools were measured with user experience questionnaires and usage logs. Results A total of 24 subjects were randomized: 11 participants were followed up in the intervention group (1 was lost to follow-up) and 12 participants did not receive any intervention (control group). Depressive and psychological symptoms decreased and self-rated health and working ability increased. All participants reported they had benefited from the intervention. All technology tools had active users and 10/11 participants used at least 1 tool actively. Physiological measurements with personal feedback were considered the most useful intervention component. Conclusions
Han, Win T; Collie, Kate; Koopman, Cheryl; Azarow, Jay; Classen, Catherine; Morrow, Gary R; Michel, Betsy; Brennan-O'Neill, Eileen; Spiegel, David
2005-04-01
This investigation examined relationships between breast cancer patients' psychosocial characteristics (impact of the illness, traumatic stress symptoms, emotional self-efficacy, and social support) and problems they perceived in their medical interactions and their satisfaction with their physicians. Participants were 352 women enrolled in a multicenter trial of the effects of group therapy for women with recently diagnosed primary breast cancer. The findings reported here are from a cross-sectional analysis of baseline data gathered prior to randomization. Problems interacting with physicians and nurses were associated with greater levels of cancer-related traumatic stress (p < 0.01), less emotional self-efficacy for cancer (p < 0.05), less satisfaction with informational support from family, friends, and spouse, and a tendency to perceive those sources of support as more aversive (p < 0.05). Women who were less satisfied with emotional support from their family, friends and spouse were less likely to feel satisfied with their physicians (p < 0.05). These patient characteristics identify women with primary breast cancer who are likely to experience difficulty in their interactions with nurses and physicians and to be less satisfied with their physicians.
Schiffmann, Florian; VandeVondele, Joost, E-mail: Joost.VandeVondele@mat.ethz.ch [Nanoscale Simulations, Department of Materials, ETH Zürich, Wolfgang-Pauli-Str. 27, CH-8093 Zürich (Switzerland)
2015-06-28
We present an improved preconditioning scheme for electronic structure calculations based on the orbital transformation method. First, a preconditioner is developed which includes information from the full Kohn-Sham matrix but avoids computationally demanding diagonalisation steps in its construction. This reduces the computational cost of its construction, eliminating a bottleneck in large scale simulations, while maintaining rapid convergence. In addition, a modified form of Hotelling’s iterative inversion is introduced to replace the exact inversion of the preconditioner matrix. This method is highly effective during molecular dynamics (MD), as the solution obtained in earlier MD steps is a suitable initial guess. Filtering small elements during sparse matrix multiplication leads to linear scaling inversion, while retaining robustness, already for relatively small systems. For system sizes ranging from a few hundred to a few thousand atoms, which are typical for many practical applications, the improvements to the algorithm lead to a 2-5 fold speedup per MD step.
Multi-scale problem in the model of RNA virus evolution
Korobeinikov, Andrei; Archibasov, Aleksei; Sobolev, Vladimir
2016-06-01
A mathematical or computational model in evolutionary biology should necessary combine several comparatively fast processes, which actually drive natural selection and evolution, with a very slow process of evolution. As a result, several very different time scales are simultaneously present in the model; this makes its analytical study an extremely difficult task. However, the significant difference of the time scales implies the existence of a possibility of the model order reduction through a process of time separation. In this paper we conduct the procedure of model order reduction for a reasonably simple model of RNA virus evolution reducing the original system of three integro-partial derivative equations to a single equation. Computations confirm that there is a good fit between the results for the original and reduced models.
Cristian Zanon
2016-01-01
Full Text Available Abstract The present longitudinal study tested hypotheses about the relationship of subjective well-being and neuroticism with rumination, anxiety, and post-traumatic stress in university students after a large scale disaster. Measures of subjective well-being and personality were obtained two months before the 2013 Santa Maria’s fire. Measures of rumination, PTSD and anxiety were collected five months after the disaster with the same students. The results provide evidence that life satisfaction correlated negatively with rumination, anxiety, and post-traumatic stress. Positive affect presented similar but slightly smaller negative correlations with these variables, while negative affect presented higher correlations with rumination, anxiety, and post-traumatic stress. These findings provide evidence that subjective well-being components may constitute important predictors of psychopathological symptomatology after a disaster and may be helpful to plan clinical interventions.
LIU Zheng-Feng; WANG Xiao-Hong
2008-01-01
Adopting Yoshizawa's two-scale expansion technique,the fluctuating field is expanded around the isotropic field.The renormalization group method is applied for calculating the covariance of the fluctuating field at the lower order expansion,A nonlinear Reynolds stress model is derived and the turbulent constants inside are evaluated analytically.Compared with the two-scale direct interaction approximation analysis for turbulent shear flows proposed by Yoshizawa,the calculation is much more simple.The analytical model presented here is close to the Speziale model,which is widely applied in the numerical simulations for the complex turbulent flows.
Salomon Estebanez, Maria; Mohamed, Zainab; Michaelidou, Maria; Collins, Hannah; Rigby, Lindsey; Skae, Mars; Padidela, Raja; Rust, Stewart; Dunne, Mark; Cosgrove, Karen; Banerjee, Indraneel; Nicholson, Jacqueline
2017-01-01
Background Congenital Hyperinsulinism (CHI) is a disease of severe hypoglycaemia caused by excess insulin secretion and associated with adverse neurodevelopment in a third of children. The Vineland Adaptive Behavior Scales Second Edition (VABS-II) is a parent report measure of adaptive functioning that could be used as a developmental screening tool in patients with CHI. We have investigated the performance of VABS-II as a screening tool to identify developmental delay in a relatively large c...
Lindstedt series and Hamilton-Jacobi equation for hyperbolic tori in three time scales problems
Gallavotti, G; Mastropietro, V; Gallavotti, Giovannni; Gentile, Guido; Astropietro, Vieri M
1998-01-01
Interacting systems consisting of two rotators and a pendulum are considered, in a case in which the uncoupled systems have three very different characteristic time scales. The abundance of unstable quasi periodic motions in phase space is studied via Lindstedt series. The result is a strong improvement, compared to our previous results, on the domain of validity of bounds that imply existence of invariant tori, large homoclinic angles, long heteroclinic chains and drift--diffusion in phase space.
Dornburg, Courtney C; Stevens, Susan M; Hendrickson, Stacey M L; Davidson, George S
2009-08-01
An experiment was conducted to compare the effectiveness of individual versus group electronic brainstorming to address difficult, real-world challenges. Although industrial reliance on electronic communications has become ubiquitous, empirical and theoretical understanding of the bounds of its effectiveness have been limited. Previous research using short-term laboratory experiments have engaged small groups of students in answering questions irrelevant to an industrial setting. The present experiment extends current findings beyond the laboratory to larger groups of real-world employees addressing organization-relevant challenges during the course of 4 days. Employees and contractors at a national laboratory participated, either in a group setting or individually, in an electronic brainstorm to pose solutions to a real-world problem. The data demonstrate that (for this design) individuals perform at least as well as groups in producing quantity of electronic ideas, regardless of brainstorming duration. However, when judged with respect to quality along three dimensions (originality, feasibility, and effectiveness), the individuals significantly (p < .05) outperformed the group. When quality is used to benchmark success, these data indicate that work-relevant challenges are better solved by aggregating electronic individual responses rather than by electronically convening a group. This research suggests that industrial reliance on electronic problem-solving groups should be tempered, and large nominal groups may be more appropriate corporate problem-solving vehicles.
From the Nano- to the Macroscale - Bridging Scales for the Moving Contact Line Problem
Nold, Andreas; Sibley, David; Goddard, Benjamin; Kalliadasis, Serafim; Complex Multiscale Systems Team
2016-11-01
The moving contact line problem remains an unsolved fundamental problem in fluid mechanics. At the heart of the problem is its multiscale nature: a nanoscale region close to the solid boundary where the continuum hypothesis breaks down, must be resolved before effective macroscale parameters such as contact line friction and slip can be obtained. To capture nanoscale properties very close to the contact line and to establish a link to the macroscale behaviour, we employ classical density-functional theory (DFT), in combination with extended Navier-Stokes-like equations. Using simple models for viscosity and slip at the wall, we compare our computations with the Molecular Kinetic Theory, by extracting the contact line friction, depending on the imposed temperature of the fluid. A key fluid property captured by DFT is the fluid layering at the wall-fluid interface, which has a large effect on the shearing properties of a fluid. To capture this crucial property, we propose an anisotropic model for the viscosity, which also allows us to scrutinize the effect of fluid layering on contact line friction.
Hairul Anuar Hashim
2011-01-01
Full Text Available Background: Psychometrically sound measurement instrument is a fundamental requirement across broad range of research areas. In negative affect research, Depression Anxiety Stress Scale (DASS has been identified as a psychometrically sound instrument to measure depression, anxiety and stress, especially the 21-item version. However, its psychometric properties in adolescents have been less consistent. Objectives: Thus, the present study sought to examine the factorial validity and internal consistency of the adapted 21-item version of DASS in Malaysian adolescents. Method: Using cross-sectional study design, DASS-21 was administered to 750 Malaysian adolescents (Mean age = 13.40 ± 0.49. The data were then analyzed using Confirmatory factor analysis (CFA, in which the original DASS-21 factor structure (depression-stress-anxiety was compared to 8 other alternative models.Results: CFA results revealed a weak support for DASS-21 as a differentiated measure of depression, anxiety and stress in Malaysian adolescents. Extremely high latent factors intercorrelations were observed in the model reflecting original DASS factor structure. On the other hand, despite the best overall fit of a 4-factor model consisting of depression, anxiety, and stress, as well as a general negative affect factor, individual factor loadings for the specific factors were uninterpretable. Although model fit of 1-factor model was inferior when compared the other competing models, this model (1-factor exhibit reasonable model fit. Conclusion: We concluded that the use of Malaysian adapted DASS-21 as a differentiated measure stress, anxiety, and depression in Malaysian adolescent should proceed with caution and further refinement of the scale is necessary before a concrete conclusion can be made.
Dalal Ben Loubir; Zeineb Serhier; Omar Battas; Mohamed Agoub; Mohammed Bennani Othmani
2014-01-01
This study was conducted to examine the psychometric properties of the classic Arabic version of the 10-item Perceived Stress Scale (PSS10) in a large sample of Moroccan population. A cross-sectional survey was yielded between December 2013 and January 2014 following an accidental sampling. Individuals aged above 18, from different socioeconomic categories, were invited to take part in the study. The participants had c...
Gildas Bourdais
2015-07-01
Full Text Available Cysteine-rich receptor-like kinases (CRKs are transmembrane proteins characterized by the presence of two domains of unknown function 26 (DUF26 in their ectodomain. The CRKs form one of the largest groups of receptor-like protein kinases in plants, but their biological functions have so far remained largely uncharacterized. We conducted a large-scale phenotyping approach of a nearly complete crk T-DNA insertion line collection showing that CRKs control important aspects of plant development and stress adaptation in response to biotic and abiotic stimuli in a non-redundant fashion. In particular, the analysis of reactive oxygen species (ROS-related stress responses, such as regulation of the stomatal aperture, suggests that CRKs participate in ROS/redox signalling and sensing. CRKs play general and fine-tuning roles in the regulation of stomatal closure induced by microbial and abiotic cues. Despite their great number and high similarity, large-scale phenotyping identified specific functions in diverse processes for many CRKs and indicated that CRK2 and CRK5 play predominant roles in growth regulation and stress adaptation, respectively. As a whole, the CRKs contribute to specificity in ROS signalling. Individual CRKs control distinct responses in an antagonistic fashion suggesting future potential for using CRKs in genetic approaches to improve plant performance and stress tolerance.
Rayapuram, Channabasavangowda; Idänheimo, Niina; Hunter, Kerri; Kimura, Sachie; Merilo, Ebe; Vaattovaara, Aleksia; Oracz, Krystyna; Kaufholdt, David; Pallon, Andres; Anggoro, Damar Tri; Glów, Dawid; Lowe, Jennifer; Zhou, Ji; Mohammadi, Omid; Puukko, Tuomas; Albert, Andreas; Lang, Hans; Ernst, Dieter; Kollist, Hannes; Brosché, Mikael; Durner, Jörg; Borst, Jan Willem; Collinge, David B.; Karpiński, Stanisław; Lyngkjær, Michael F.; Robatzek, Silke; Wrzaczek, Michael; Kangasjärvi, Jaakko
2015-01-01
Cysteine-rich receptor-like kinases (CRKs) are transmembrane proteins characterized by the presence of two domains of unknown function 26 (DUF26) in their ectodomain. The CRKs form one of the largest groups of receptor-like protein kinases in plants, but their biological functions have so far remained largely uncharacterized. We conducted a large-scale phenotyping approach of a nearly complete crk T-DNA insertion line collection showing that CRKs control important aspects of plant development and stress adaptation in response to biotic and abiotic stimuli in a non-redundant fashion. In particular, the analysis of reactive oxygen species (ROS)-related stress responses, such as regulation of the stomatal aperture, suggests that CRKs participate in ROS/redox signalling and sensing. CRKs play general and fine-tuning roles in the regulation of stomatal closure induced by microbial and abiotic cues. Despite their great number and high similarity, large-scale phenotyping identified specific functions in diverse processes for many CRKs and indicated that CRK2 and CRK5 play predominant roles in growth regulation and stress adaptation, respectively. As a whole, the CRKs contribute to specificity in ROS signalling. Individual CRKs control distinct responses in an antagonistic fashion suggesting future potential for using CRKs in genetic approaches to improve plant performance and stress tolerance. PMID:26197346
Elena Maggi
2016-10-01
Full Text Available Background Organisms are facing increasing levels of environmental stress under climate change that may severely affect the functioning of biological systems at different levels of organization. Growing evidence suggests that reduction in body size is a universal response of organisms to global warming. However, a clear understanding of whether extreme climate events will impose selection directly on phenotypic plastic responses and how these responses affect ecological interactions has remained elusive. Methods We experimentally investigated the effects of extreme desiccation events on antioxidant defense mechanisms of a rocky intertidal gastropod (Patella ulyssiponensis, and evaluated how these effects scaled-up at the population and assemblage levels. Results With increasing levels of desiccation stress, limpets showed significant lower levels of total glutathione, tended to grow less and had reduced per capita interaction strength on their resources. Discussion Results suggested that phenotypic plasticity (i.e., reduction in adults’ body size allowed buffering biochemical responses to stress to scale-up at the assemblage level. Unveiling the linkages among different levels of biological organization is key to develop indicators that can anticipate large-scale ecological impacts of climate change.
Cappiello, Mario; Del Corso, Antonella; Lenzarini, Francesca; Peroni, Eleonora; Benedetti-Cecchi, Lisandro
2016-01-01
Background Organisms are facing increasing levels of environmental stress under climate change that may severely affect the functioning of biological systems at different levels of organization. Growing evidence suggests that reduction in body size is a universal response of organisms to global warming. However, a clear understanding of whether extreme climate events will impose selection directly on phenotypic plastic responses and how these responses affect ecological interactions has remained elusive. Methods We experimentally investigated the effects of extreme desiccation events on antioxidant defense mechanisms of a rocky intertidal gastropod (Patella ulyssiponensis), and evaluated how these effects scaled-up at the population and assemblage levels. Results With increasing levels of desiccation stress, limpets showed significant lower levels of total glutathione, tended to grow less and had reduced per capita interaction strength on their resources. Discussion Results suggested that phenotypic plasticity (i.e., reduction in adults’ body size) allowed buffering biochemical responses to stress to scale-up at the assemblage level. Unveiling the linkages among different levels of biological organization is key to develop indicators that can anticipate large-scale ecological impacts of climate change. PMID:27781156
Y. Y. Yan
2007-01-01
Over the last decade, computational methods have been intensively applied to a variety of scientific researches and engineering designs. Although the computational fluid dynamics (CFD) method has played a dominant role in studying and simulating transport phenomena involving fluid flow and heat and mass transfers, in recent years, other numerical methods for the simulations at meso- and micro-scales have also been actively applied to solve the physics of complex flow and fluid-interface interactions. This paper presents a review of recent advances in multi-scale computational simulation of biomimetics related fluid flow problems. The state-of-the-art numerical techniques, such as lattice Boltzmann method (LBM), molecular dynamics (MD), and conventional CFD, applied to different problems such as fish flow, electro-osmosis effect of earthworm motion, and self-cleaning hydrophobic surface, and the numerical approaches are introduced. The new challenging of modelling biomimetics problems in developing the physical conditions of self-clean hydrophobic surfaces is discussed.
Bui-Thanh, T.; Girolami, M.
2014-11-01
We consider the Riemann manifold Hamiltonian Monte Carlo (RMHMC) method for solving statistical inverse problems governed by partial differential equations (PDEs). The Bayesian framework is employed to cast the inverse problem into the task of statistical inference whose solution is the posterior distribution in infinite dimensional parameter space conditional upon observation data and Gaussian prior measure. We discretize both the likelihood and the prior using the H1-conforming finite element method together with a matrix transfer technique. The power of the RMHMC method is that it exploits the geometric structure induced by the PDE constraints of the underlying inverse problem. Consequently, each RMHMC posterior sample is almost uncorrelated/independent from the others providing statistically efficient Markov chain simulation. However this statistical efficiency comes at a computational cost. This motivates us to consider computationally more efficient strategies for RMHMC. At the heart of our construction is the fact that for Gaussian error structures the Fisher information matrix coincides with the Gauss-Newton Hessian. We exploit this fact in considering a computationally simplified RMHMC method combining state-of-the-art adjoint techniques and the superiority of the RMHMC method. Specifically, we first form the Gauss-Newton Hessian at the maximum a posteriori point and then use it as a fixed constant metric tensor throughout RMHMC simulation. This eliminates the need for the computationally costly differential geometric Christoffel symbols, which in turn greatly reduces computational effort at a corresponding loss of sampling efficiency. We further reduce the cost of forming the Fisher information matrix by using a low rank approximation via a randomized singular value decomposition technique. This is efficient since a small number of Hessian-vector products are required. The Hessian-vector product in turn requires only two extra PDE solves using the adjoint
Neelov, Alexey; Ghasemi, S Alireza; Goedecker, Stefan
2007-07-14
An algorithm for fast calculation of the Coulombic forces and energies of point particles with free boundary conditions is proposed. Its calculation time scales as N log N for N particles. This novel method has lower crossover point with the full O(N(2)) direct summation than the fast multipole method. The forces obtained by our algorithm are analytical derivatives of the energy which guarantees energy conservation during a molecular dynamics simulation. Our algorithm is very simple. A version of the code parallelized with the Message Passing Interface can be downloaded under the GNU General Public License from the website of our group.
Multi-scale modeling of follicular ovulation as a reachability problem
Echenim, Nki; Sorine, Michel
2007-01-01
During each ovarian cycle, only a definite number of follicles ovulate, while the others undergo a degeneration process called atresia. We have designed a multi-scale mathematical model where ovulation and atresia result from a hormonal controlled selection process. A 2D-conservation law describes the age and maturity structuration of the follicular cell population. In this paper, we focus on the operating mode of the control, through the study of the characteristics of the conservation law. We describe in particular the set of microscopic initial conditions leading to the macroscopic phenomenon of either ovulation or atresia, in the framework of backwards reachable sets theory.
Gentrification and urban children's well-being: tipping the scales from problems to promise.
Formoso, Diana; N Weber, Rachel; S Atkins, Marc
2010-12-01
Gentrification changes the neighborhood and family contexts in which children are socialized-for better and worse-yet little is known about its consequences for youth. This review, drawn from research in urban planning, sociology, and psychology, maps out mechanisms by which gentrification may impact children. We discuss indicators of gentrification and link neighborhood factors, including institutional resources and collective socialization, to family processes more proximally related to child development. Finally, we discuss implications for intervention and public policy recommendations that are intended to tip the scales toward better outcomes for low-income youth in gentrifying areas.
María Cristina Pinto-Dussán
2010-02-01
Full Text Available Stress is an adaptive response that may involve adverse changes in the medium and long term. Research showed that maternal stress during pregnancy may have variables effects on the offspring development. The objective of this study was to describe the cognitive characteristics of children from Bogota- Colombia, whose mothers during neuropsychological consultation, reported stress during pregnancy as the only risk factor. Cognitive profiles are described from neuropsychological assessments, highlighting significant scores in the subtest and global indices of the WISC IV scale. It was foundthat children whose mothers suffer stress during pregnancy have deficits in attention, executive functions and processing speed.
Numerical models of catchment scale sediment transfer: progress, problems and potential
Coulthard, T. J.
2009-05-01
The sediment output from a drainage basin reflects the modification and filtering of 'inputs' into the system. These 'inputs' can be internal (e.g. drainage basin configuration, sediment size and supply) or external (e.g. tectonic uplift or climatic changes). There is much interest in the relative importance of these internal and external forcings/inputs to understand past basin evolution, but also to understand and predict future development, particularly in response to human influences such as land cover modification and climate change. Numerical modelling can be a powerful tool to explore these forcings and their interactions with drainage basins. This paper reviews the state of the art for numerical simulation of sediment transfer within drainage basins over a range of time and space scales (millennia to decades, sub km to thousands of square km basins). In particular, it will examine the role of autogenic processes relative to the more classic forcings, such as climate. The paper will also examine the many limitations associated with modelling drainage basins including parameterisation and process representation looking at the widespread simplifications that are required to simulate basin processes over long time scales. Finally it concludes by discussing the potential and future direction for drainage basin modelling and how these models may benefit from close collaboration with physical modelling studies.
Scott, Brandon G; Sanders, Ashley F P; Graham, Rebecca A; Banks, Donice M; Russell, Justin D; Berman, Steven L; Weems, Carl F
2014-10-01
Identity distress involves intense or prolonged upset or worry about personal identity issues including long-term goals, career choice, friendships, sexual orientation and behavior, religion, values and beliefs, and group loyalties. Research suggests that trauma exposure and subsequent PTSD symptoms may negatively impact identity development and psychological adjustment. However, little is known about their specific associations with identity distress and internalizing problems among disaster-exposed adolescents. The purpose of this study was to examine these relationships in a sample of 325 adolescents (60% female; 89% African American) who experienced a major natural disaster and its aftermath. The results indicated that identity distress was positively associated with age, hurricane exposure, PTSD symptoms, and internalizing problems. Linear regression analyses also showed that identity distress was uniquely associated with internalizing symptoms and that there was an indirect effect of hurricane exposure on identity distress via PTSD symptoms. Finally, PTSD symptoms moderated the link between identity distress and internalizing symptoms, with a significant positive slope found for youth with more PTSD symptoms. Findings were generally consistent with previous work and predictions, and add to the extant knowledge about identity distress by providing data on the linkages between disaster exposure, posttraumatic stress and internalizing problems in adolescents.
Soltani, Sara
In this report, we address the problem of low-dose tomographic image reconstruction using dictionary priors learned from training images. In our recent work [22] dictionary learning is used to incorporate priors from training images and construct a dictionary, and then the reconstruction problem...... is formulated in a convex optimization framework by looking for a solution with a sparse representation in the subspace spanned by the dictionary. The work in [22] has shown that using learned dictionaries in computed tomography can lead to superior image reconstructions comparing to classical methods. Our...... formulation in [22] enforces that the solution is an exact representation by the dictionary; in this report, we investigate this requirement. Furthermore, the underlying assumption that the scale and orientation of the training images are consistent with the unknown image of interest may not be realistic. We...
Quoc, Tran Dinh; Diehl, Moritz
2011-01-01
A new algorithm for solving large-scale separable convex optimization problems is proposed. The basic idea is to combine three techniques including Lagrangian dual decomposition, excessive gap and smoothing techniques. The main advantage of this algorithm is to dynamically update the smoothness parameters which leads to a numerically stable performance ability. The convergence of the algorithm is proved under weak conditions imposed on the original problem. The worst-case complexity is estimated which is $O(1/k)$, where $k$ is the iteration counter. Then, the algorithm is coupled with a dual scheme to construct a switching variant of the dual decomposition. Discussion on the implementation issues is presented and theoretical comparison is analyzed. Numerical results are implemented to confirm the theoretical development.
The Effect of Current-Induced Stress Perturbation on - and Meso-Scale Air-Sea Interactions.
Xie, Lian
The effect of the stress modulation by the surface currents is studied using a quadratic stress law, for various physical processes in the atmosphere-ocean system. In the presence of surface currents, a stress perturbation is induced by the current structure because of a modulation of the velocity shear at the air-sea interface. In the case of a unidirectional current and a uniform wind, it is proportional to and opposing the surface current vorticity. This causes a spindown effect on the surface vorticity field at a rate proportional to the wind speed. In the steady state, or in slowly varying processes which can be treated as parametrically developing quasi-steady states, the surface -layer potential vorticity modulation causes up- and down -welling patterns associated with the surface-current vorticity. These effects are analyzed, first in a 2.5-layer quasi-geostrophic (QG) f-plane system and then in a two-layer as well as in a continuously stratified QG beta -plane systems. The f-plane solution shows that the damping effect is effectively limited to the surface layer. The beta-plane solution shows that the perturbation stress induced by the surface current is an important damping mechanism for the baroclinic Rossby waves. The responses of the tropical atmosphere-ocean system to the current-induced stress perturbation are explored in a simple coupled model. We find that in the absence of mean currents the current-induced stress perturbation imposes a damping effect on both sides of the air-sea interface. In the presence of a mean current, the stress perturbation created by the mean current imposes a damping effect on the mean current itself, but can enhance the perturbation flow field through momentum exchanges between the two mediated by the interface stress. The coupling strength of the atmosphere -ocean system is thus modulated by the stress perturbation. Finally, the reactionary effect of the current-induced stress perturbation on the atmospheric boundary
The effect of current-induced stress perturbation on large- and meso-scale air-sea interactions
Xie, Lian
The effect of the stress modulation by the surface currents is studied using a quadratic stress law, for various physical processes in the atmosphere-ocean system. In the presence of surface currents, a stress perturbation is induced by the current structure because of a modulation of the velocity shear at the air-sea interface. In the case of a unidirectional current and a uniform wind, it is proportional to and opposing the surface current vorticity. This causes a spindown effect on the surface vorticity field at a rate proportional to the wind speed. In the steady state, or in slowly varying processes which can be treated as parametrically developing quasi-steady states, the surface layer potential vorticity modulation causes up- and down-welling patterns associated with the surface-current vorticity. These effects are analyzed, first in a 2.5-layer quasi-geostrophic (QG) f-plane system and then in a two-layer as well as in a continuously stratified QG beta-plane system. The f-plane solution shows that the damping effect is effectively limited to the surface layer. The beta-plane solution shows that the perturbation stress induced by the surface current is an important damping mechanism for the baroclinic Rossby waves. The responses of the tropical atmosphere-ocean system to the current-induced stress perturbation are explored in a simple coupled model. We find that in the absence of mean currents the current-induced stress perturbation imposes a damping effect on both sides of the air-sea interface. In the presence of a mean current, the stress perturbation created by the mean current imposes a damping effect on the mean current itself, but can enhance the perturbation flow field through momentum exchanges between the two mediated by the interface stress. The coupling strength of the atmosphere-ocean system is thus modulated by the stress perturbation. Finally, the reactionary effect of the current induced stress perturbation on the atmospheric boundary
Effects of stress on pain in horses and incorporating pain scales for equine practice.
Wagner, Ann E
2010-12-01
The stress response represents an animal's attempt to reestablish the body's homeostasis after injury, intense physical activity, or psychological strain. Two different neuroendocrine pathways may be activated in stressful situations: the hypothalamic-pituitary-adrenocortical axis, leading to increased cortisol levels, and the sympathoadrenomedullar system, leading to increased catecholamine levels. By applying some of the evaluation methods described in this article in the appropriate clinical situations, equine veterinarians can almost certainly improve their ability to recognize and manage pain in horses.
Widyanto, L; Griffiths, MD; Brunsden, V
2011-01-01
One of the more prominent issues in the field of Internet addiction is the validity of the instrument used to assess users’ level of Internet involvement. Many of the instruments used to assess Internet addiction have high face validity but have yet to be tested psychometrically. The aim of this study is to compare two of the most used Internet addiction research measures, the Internet Addiction Test (IAT) and the Internet-Related Problem Scale (IRPS), along with a self-diagnostic question si...
Keller, Hanne Dauer
2015-01-01
Kapitlet handler om stress som følelse, og det trækker primært på de få kvalitative undersøgelser, der er lavet af stressforløb.......Kapitlet handler om stress som følelse, og det trækker primært på de få kvalitative undersøgelser, der er lavet af stressforløb....
Keller, Hanne Dauer
2015-01-01
Kapitlet handler om stress som følelse, og det trækker primært på de få kvalitative undersøgelser, der er lavet af stressforløb.......Kapitlet handler om stress som følelse, og det trækker primært på de få kvalitative undersøgelser, der er lavet af stressforløb....
Cui, Tiangang; Marzouk, Youssef; Willcox, Karen
2016-06-01
Two major bottlenecks to the solution of large-scale Bayesian inverse problems are the scaling of posterior sampling algorithms to high-dimensional parameter spaces and the computational cost of forward model evaluations. Yet incomplete or noisy data, the state variation and parameter dependence of the forward model, and correlations in the prior collectively provide useful structure that can be exploited for dimension reduction in this setting-both in the parameter space of the inverse problem and in the state space of the forward model. To this end, we show how to jointly construct low-dimensional subspaces of the parameter space and the state space in order to accelerate the Bayesian solution of the inverse problem. As a byproduct of state dimension reduction, we also show how to identify low-dimensional subspaces of the data in problems with high-dimensional observations. These subspaces enable approximation of the posterior as a product of two factors: (i) a projection of the posterior onto a low-dimensional parameter subspace, wherein the original likelihood is replaced by an approximation involving a reduced model; and (ii) the marginal prior distribution on the high-dimensional complement of the parameter subspace. We present and compare several strategies for constructing these subspaces using only a limited number of forward and adjoint model simulations. The resulting posterior approximations can rapidly be characterized using standard sampling techniques, e.g., Markov chain Monte Carlo. Two numerical examples demonstrate the accuracy and efficiency of our approach: inversion of an integral equation in atmospheric remote sensing, where the data dimension is very high; and the inference of a heterogeneous transmissivity field in a groundwater system, which involves a partial differential equation forward model with high dimensional state and parameters.
Nuclear three-body problem in the complex energy plane: Complex-Scaling-Slater method
Kruppa, A T; Nazarewicz, W; Michel, N
2013-01-01
The physics of open quantum systems is an interdisciplinary area of research. The nuclear "openness" manifests itself through the presence of the many-body continuum representing various decay, scattering, and reaction channels. As the radioactive nuclear beam experimentation extends the known nuclear landscape towards the particle drip lines, the coupling to the continuum space becomes exceedingly more important. Of particular interest are weakly bound and unbound nuclear states appearing around particle thresholds. Theories of such nuclei must take into account their open quantum nature. To describe open quantum systems, we introduce a Complex Scaling (CS) approach in the Slater basis. We benchmark it with the complex-energy Gamow Shell Model (GSM) by studying energies and wave functions of the bound and unbound states of the two-neutron halo nucleus 6He viewed as an $\\alpha$+ n + n cluster system. In the CS approach, we use the Slater basis, which exhibits the correct asymptotic behavior at large distances...
Large-scale Inference Problems in Astronomy: Building a 3D Galactic Dust Map
Finkbeiner, Douglas
2016-03-01
The term ''Big Data'' has become trite, as modern technology has made data sets of terabytes or even petabytes easy to store. Such data sets provide a sandbox in which to develop new statistical inference techniques that can extract interesting results from increasingly rich (and large) databases. I will give an example from my work on mapping the interstellar dust of the Milky Way. 2D emission-based maps have been used for decades to estimate the reddening and emission from interstellar dust, with applications from CMB foregrounds to surveys of large-scale structure. For studies within the Milky Way, however, the third dimension is required. I will present our work on a 3D dust map based on Pan-STARRS1 and 2MASS over 3/4 of the sky (http://arxiv.org/abs/1507.01005), assess its usefulness relative to other dust maps, and discuss future work. Supported by the NSF.
Solving Man-Induced Large-Scale Conservation Problems: The Spanish Imperial Eagle and Power Lines
López-López, Pascual; Ferrer, Miguel; Madero, Agustín; Casado, Eva; McGrady, Michael
2011-01-01
Background Man-induced mortality of birds caused by electrocution with poorly-designed pylons and power lines has been reported to be an important mortality factor that could become a major cause of population decline of one of the world rarest raptors, the Spanish imperial eagle (Aquila adalberti). Consequently it has resulted in an increasing awareness of this problem amongst land managers and the public at large, as well as increased research into the distribution of electrocution events and likely mitigation measures. Methodology/Principal Findings We provide information of how mitigation measures implemented on a regional level under the conservation program of the Spanish imperial eagle have resulted in a positive shift of demographic trends in Spain. A 35 years temporal data set (1974–2009) on mortality of Spanish imperial eagle was recorded, including population censuses, and data on electrocution and non-electrocution of birds. Additional information was obtained from 32 radio-tracked young eagles and specific field surveys. Data were divided into two periods, before and after the approval of a regional regulation of power line design in 1990 which established mandatory rules aimed at minimizing or eliminating the negative impacts of power lines facilities on avian populations. Our results show how population size and the average annual percentage of population change have increased between the two periods, whereas the number of electrocuted birds has been reduced in spite of the continuous growing of the wiring network. Conclusions Our results demonstrate that solving bird electrocution is an affordable problem if political interest is shown and financial investment is made. The combination of an adequate spatial planning with a sustainable development of human infrastructures will contribute positively to the conservation of the Spanish imperial eagle and may underpin population growth and range expansion, with positive side effects on other endangered
Problems associated with glucose toxicity: Role of hyperglycemia-induced oxidative stress
Shinji Kawahito; Hiroshi Kitahata; Shuzo Oshita
2009-01-01
Glucose homeostasis deficiency leads to a chronic increase in blood glucose concentration. In contrast to physiological glucose concentration, chronic superphysiological glucose concentration negatively affects a large number of organs and tissues. Glucose toxicity means a decrease in insulin secretion and an increase in insulin resistance due to chronic hyperglycemia. It is now generally accepted that glucose toxicity is involved in the worsening of diabetes by affecting the secretion of β-cells. Several mechanisms have been proposed to explain the adverse effects of hyperglycemia.It was found that persistent hyperglycemia caused the functional decline of neutrophils. Infection is thus the main problem resulting from glucose toxicity in the acute phase. In other words, continued hyperglycemia is a life-threatening risk factor, not only in the chronic but also the acute phase, and it becomes a risk factor for infection, particularly in the perioperative period.
Problems associated with glucose toxicity: Role of hyperglycemia-induced oxidative stress
Kawahito, Shinji; Kitahata, Hiroshi; Oshita, Shuzo
2009-01-01
Glucose homeostasis deficiency leads to a chronic increase in blood glucose concentration. In contrast to physiological glucose concentration, chronic superphysiological glucose concentration negatively affects a large number of organs and tissues. Glucose toxicity means a decrease in insulin secretion and an increase in insulin resistance due to chronic hyperglycemia. It is now generally accepted that glucose toxicity is involved in the worsening of diabetes by affecting the secretion of β-cells. Several mechanisms have been proposed to explain the adverse effects of hyperglycemia. It was found that persistent hyperglycemia caused the functional decline of neutrophils. Infection is thus the main problem resulting from glucose toxicity in the acute phase. In other words, continued hyperglycemia is a life-threatening risk factor, not only in the chronic but also the acute phase, and it becomes a risk factor for infection, particularly in the perioperative period. PMID:19725147
马海林; 马慧芳
2013-01-01
Objective To explore the relationship betwee life stress and problem behaviors among Tibetan university students and to provide scientific basis for psychological health education.Methods We investigated 400 Tibetan college students with life stress scale and teenage behavior questionnaire.Results Life stress and problem behaviors were positively correlated(all P ＜ 0.01) in the students.The study and life stress had significant effect on school maladjustment (β ＝-0.209) and test anxiety(β ＝-0.284).Peer relationships affected retreat(β ＝-0.252) and neuroticism significantly(β ＝-0.243).The development of the relationship between male and female had significant influence on attack (β ＝-0.146) and discipline (β ＝-0.306).Self-identity and self-expectation of life pressure affected four dimensions of school maladjustment (β ＝-0.213),withdrawn (β ＝-0.293),neuroticism (β ＝-0.233) and test anxiety (β ＝-0.293).Conclusion Life stress influences the generation of problem behavior among Tibetan college students.%目的 探讨藏族大学生生活压力与问题行为关系,为藏族大学生心理健康教育提供科学依据.方法 采用生活经验问卷和青少年问题行为问卷对399名藏族大学生进行间卷调查.结果 (1)藏族大学生生活压力各维度与问题行为各维度之间均存在相关关系(均P ＜0.01)；(2)生活压力的学业压力维度对学业适应不良(β=-0.209)和考试焦虑(β＝-0.284)2个维度有明显影响；同伴人际关系维度对退缩(β＝-0.252)和神经质(β＝-0.243)2个维度有明显影响；异性关系发展对攻击行为(β＝-0.146)和违纪(β＝-0.306)2个维度有明显影响；生活压力的自我认同与期许维度对学业适应不良(β＝-0.213)、退缩(β＝-0.293)、神经质(β＝-0.233)和考试焦虑(β=-0.293)4个维度有明显影响.结论 藏族大学生生活压力会影响行为问题的产生,学校健康教育工作应帮助学生减少各种生活
Janete de Souza Urbanetto
2011-10-01
Full Text Available This study identifies workplace stress according to the Job Stress Scale and associates it with socio-demographic and occupational variables of nursing workers from an emergency hospital. This is a cross-sectional study and data were collected through a questionnaire applied to 388 nursing professionals. Descriptive statistics were applied; univariate and multivariate analyses were performed. The results indicate there is a significant association with being a nursing technician or auxiliary, working in the position for more than 15 years, and having low social support, with 3.84, 2.25 and 4.79 times more chances of being placed in the ‘high strain job' quadrant. The study reveals that aspects related to the workplace should be monitored by competent agencies in order to improve the quality of life of nursing workers.Estudio que tuvo el objetivo identificar el estrés en el trabajo, según la Job Stress Scale y asociarlo con aspectos sociodemográficos y laborales de trabajadores de enfermería de un hospital de emergencia. Estudio de tipo transversal, cuyos datos fueron recolectados, por medio de cuestionario, con 388 profesionales de enfermería. El análisis fue realizado con la estadística descriptiva, análisis univariado y multivariado. Los resultados identificaron asociación significativa con el cargo de técnico/auxiliar de enfermería, tiempo en el cargo superior a 15 años y bajo apoyo social, con chances respectivas de 3,84; 2,25 y 4,79 mayores para el cuadrante alto desgaste. El estudio demostró que los aspectos relacionados al ambiente de trabajo deben ser acompañados por los órganos competentes con la finalidad de invertir recursos en la calidad de vida en el trabajo de la enfermería.Trata-se de estudo cujo objetivo foi identificar o estresse no trabalho, segundo a Job Stress Scale, e associá-lo aos aspectos sociodemográficos e laborais de trabalhadores de enfermagem de um hospital de pronto-socorro. É estudo tipo
Large and small-scale structures and the dust energy balance problem in spiral galaxies
Saftly, W; De Geyter, G; Camps, P; Renaud, F; Guedes, J; De Looze, I
2015-01-01
The interstellar dust content in galaxies can be traced in extinction at optical wavelengths, or in emission in the far-infrared. Several studies have found that radiative transfer models that successfully explain the optical extinction in edge-on spiral galaxies generally underestimate the observed FIR/submm fluxes by a factor of about three. In order to investigate this so-called dust energy balance problem, we use two Milky Way-like galaxies produced by high-resolution hydrodynamical simulations. We create mock optical edge-on views of these simulated galaxies (using the radiative transfer code SKIRT), and we then fit the parameters of a basic spiral galaxy model to these images (using the fitting code FitSKIRT). The basic model includes smooth axisymmetric distributions along a S\\'ersic bulge and exponential disc for the stars, and a second exponential disc for the dust. We find that the dust mass recovered by the fitted models is about three times smaller than the known dust mass of the hydrodynamical in...
SCALE Modeling of Selected Neutronics Test Problems within the OECD UAM LWR’s Benchmark
Luigi Mercatali
2013-01-01
Full Text Available The OECD UAM Benchmark was launched in 2005 with the objective of determining the uncertainty in the simulation of Light Water Reactors (LWRs system calculations at all the stages of the coupled reactor physics—thermal hydraulics modeling. Within the framework of the “Neutronics Phase” of the Benchmark the solutions of some selected test cases at the cell physics and lattice physics levels are presented. The SCALE 6.1 code package has been used for the neutronics modeling of the selected exercises. Sensitivity and Uncertainty analysis (S/U based on the generalized perturbation theory has been performed in order to assess the uncertainty of the computation of some selected reactor integral parameters due to the uncertainty in the basic nuclear data. As a general trend, it has been found that the main sources of uncertainty are the 238U (n, and the 239Pu nubar for the UOX- and the MOX-fuelled test cases, respectively. Moreover, the reference solutions for the test cases obtained using Monte Carlo methodologies together with a comparison between deterministic and stochastic solutions are presented.
[Validation of two brief scales for Internet addiction and mobile phone problem use].
Beranuy Fargues, Marta; Chamarro Lusar, Andrés; Graner Jordania, Carla; Carbonell Sánchez, Xavier
2009-08-01
This study describes the construction and validation process of two questionnaires designed to assess the addictive use of Internet and mobile phones. The scales were applied to a sample of 1,879 students. Results support a two-factor model, presenting an acceptable internal consistency and indices of convergent and discriminant validity. The Questionnaire of Experiences Related to Internet was found to assess intra- and interpersonal conflicts related to Internet use. The Questionnaire of Experiences Related to the Mobile Phone was found to assess conflicts related to mobile phone abuse and to maladaptive emotional and communicational patterns. Our results indicate that the mobile phone does not produce the same degree of addictive behavior as Internet; it could rather be interpreted as problematic use. Men displayed more addictive use of Internet, whilst women seemed to use the mobile phone as a means for emotional communication. It seems that the use of both technologies is more problematic during adolescence and normalizes with age toward a more professional and less playful use, and with fewer negative consequences.