Climate change, human health, and epidemiological transition.

Science.gov (United States)

Barrett, Bruce; Charles, Joel W; Temte, Jonathan L

2015-01-01

The health of populations depends on the availability of clean air, water, food, and sanitation, exposure to pathogens, toxins and environmental hazards, and numerous genetic, behavioral and social factors. For many thousands of years, human life expectancy was low, and population growth was slow. The development of technology-based civilizations facilitated what Abdel Omran called "epidemiological transition," with increasing life expectancy and rapid population growth. To a large extent, the spectacular growth of human populations during the past two centuries was made possible by the energy extracted from fossil fuels. We have now learned, however, that greenhouse gases from fossil fuel combustion are warming the planet's surface, causing changes in oceanic and atmospheric systems, and disrupting weather and hydrological patterns. Climate change poses unprecedented threats to human health by impacts on food and water security, heat waves and droughts, violent storms, infectious disease, and rising sea levels. Whether or not humanity can reduce greenhouse gas emissions quickly enough to slow climate change to a rate that will allow societies to successfully adapt is not yet known. This essay reviews the current state of relevant knowledge, and points in a few directions that those interested in human health may wish to consider. Copyright © 2014 Elsevier Inc. All rights reserved.

The Association of Dietary Fiber Intake with Cardiometabolic Risk in Four Countries across the Epidemiologic Transition

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Louise Lie

2018-05-01

Full Text Available The greatest burden of cardiovascular disease is now carried by developing countries with cardiometabolic conditions such as metabolic syndrome, obesity and inflammation believed to be the driving force behind this epidemic. Dietary fiber is known to have protective effects against obesity, type 2 diabetes, cardiovascular disease and the metabolic syndrome. Considering the emerging prevalence of these cardiometabolic disease states across the epidemiologic transition, the objective of this study is to explore these associations of dietary fiber with cardiometabolic risk factors in four countries across the epidemiologic transition. We examined population-based samples of men and women, aged 25–45 of African origin from Ghana, Jamaica, the Seychelles and the USA. Ghanaians had the lowest prevalence of obesity (10%, while Jamaicans had the lowest prevalence of metabolic syndrome (5% across all the sites. Participants from the US presented with the highest prevalence of obesity (52%, and metabolic syndrome (22%. Overall, the Ghanaians consumed the highest dietary fiber (24.9 ± 9.7 g, followed by Jamaica (16.0 ± 8.3 g, the Seychelles (13.6 ± 7.2 g and the lowest in the USA (14.2 ± 7.1 g. Consequently, 43% of Ghanaians met the fiber dietary guidelines (14 g/1000 kcal/day, 9% of Jamaicans, 6% of Seychellois, and only 3% of US adults. Across all sites, cardiometabolic risk (metabolic syndrome, inflammation and obesity was inversely associated with dietary fiber intake, such that the prevalence of metabolic syndrome was 13% for those in the lowest quartile of fiber intake, compared to 9% those in the highest quartile of fiber intake. Notably, twice as many of participants (38% in the lowest quartile were obese compared to those in the highest quartile of fiber intake (18%. These findings further support the need to incorporate strategies and policies to promote increased dietary fiber intake as one component for the prevention of cardiometabolic

Stressful life transitions and wellbeing: A comparison of the stress buffering hypothesis and the social identity model of identity change.

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Praharso, Nurul F; Tear, Morgan J; Cruwys, Tegan

2017-01-01

The relationship between stressful life transitions and wellbeing is well established, however, the protective role of social connectedness has received mixed support. We test two theoretical models, the Stress Buffering Hypothesis and the Social Identity Model of Identity Change, to determine which best explains the relationship between social connectedness, stress, and wellbeing. Study 1 (N=165) was an experiment in which participants considered the impact of moving cities versus receiving a serious health diagnosis. Study 2 (N=79) was a longitudinal study that examined the adjustment of international students to university over the course of their first semester. Both studies found limited evidence for the buffering role of social support as predicted by the Stress Buffering Hypothesis; instead people who experienced a loss of social identities as a result of a stressor had a subsequent decline in wellbeing, consistent with the Social Identity Model of Identity Change. We conclude that stressful life events are best conceptualised as identity transitions. Such events are more likely to be perceived as stressful and compromise wellbeing when they entail identity loss. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Hypothesis: does ochratoxin A cause testicular cancer?

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Schwartz, Gary G

2002-02-01

Little is known about the etiology of testicular cancer, which is the most common cancer among young men. Epidemiologic data point to a carcinogenic exposure in early life or in utero, but the nature of the exposure is unknown. We hypothesize that the mycotoxin, ochratoxin A, is a cause of testicular cancer. Ochratoxin A is a naturally occurring contaminant of cereals, pigmeat, and other foods and is a known genotoxic carcinogen in animals. The major features of the descriptive epidemiology of testicular cancer (a high incidence in northern Europe, increasing incidence over time, and associations with high socioeconomic status, and with poor semen quality) are all associated with exposure to ochratoxin A. Exposure of animals to ochratoxin A via the diet or via in utero transfer induces adducts in testicular DNA. We hypothesize that consumption of foods contaminated with ochratoxin A during pregnancy and/or childhood induces lesions in testicular DNA and that puberty promotes these lesions to testicular cancer. We tested the ochratoxin A hypothesis using ecologic data on the per-capita consumption of cereals, coffee, and pigmeat, the principal dietary sources of ochratoxin A. Incidence rates for testicular cancer in 20 countries were significantly correlated with the per-capita consumption of coffee and pigmeat (r = 0.49 and 0.54, p = 0.03 and 0.01). The ochratoxin A hypothesis offers a coherent explanation for much of the descriptive epidemiology of testicular cancer and suggests new avenues for analytic research.

Child and Adolescent Mortality Across Malaysia's Epidemiological Transition: A Systematic Analysis of Global Burden of Disease Data.

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Abdul-Razak, Suraya; Azzopardi, Peter S; Patton, George C; Mokdad, Ali H; Sawyer, Susan M

2017-10-01

A rapid epidemiological transition in developing countries in Southeast Asia has been accompanied by major shifts in the health status of children and adolescents. In this article, mortality estimates in Malaysian children and adolescents from 1990 to 2013 are used to illustrate these changes. All-cause and cause-specific mortality estimates were obtained from the 2013 Global Burden of Disease Study. Data were extracted from 1990 to 2013 for the developmental age range from 1 to 24 years, for both sexes. Trends in all-cause and cause-specific mortality for the major epidemiological causes were estimated. From 1990 to 2013, all-cause mortality decreased in all age groups. Reduction of all-cause mortality was greatest in 1- to 4-year-olds (2.4% per year reduction) and least in 20- to 24-year-olds (.9% per year reduction). Accordingly, in 2013, all-cause mortality was highest in 20- to 24-year-old males (129 per 100,000 per year). In 1990, the principal cause of death for 1- to 9-year boys and girls was vaccine preventable diseases. By 2013, neoplasms had become the major cause of death in 1-9 year olds of both sexes. The major cause of death in 10- to 24-year-old females was typhoid in 1990 and neoplasms in 2013, whereas the major cause of death in 10- to 24-year-old males remained road traffic injuries. The reduction in mortality across the epidemiological transition in Malaysia has been much less pronounced for adolescents than younger children. The contribution of injuries and noncommunicable diseases to adolescent mortality suggests where public health strategies should focus. Copyright © 2017 Society for Adolescent Health and Medicine. Published by Elsevier Inc. All rights reserved.

The social patterning of risk factors for noncommunicable diseases in five countries: evidence from the modeling the epidemiologic transition study (METS

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Silvia Stringhini

2016-09-01

Full Text Available Abstract Background Associations between socioeconomic status (SES and risk factors for noncommunicable diseases (NCD-RFs may differ in populations at different stages of the epidemiological transition. We assessed the social patterning of NCD-RFs in a study including populations with different levels of socioeconomic development. Methods Data on SES, smoking, physical activity, body mass index, blood pressure, cholesterol and glucose were available from the Modeling the Epidemiologic Transition Study (METS, with about 500 participants aged 25–45 in each of five sites (Ghana, South Africa, Jamaica, Seychelles, United States. Results The prevalence of NCD-RFs differed between these populations from five countries (e.g., lower prevalence of smoking, obesity and hypertension in rural Ghana and by sex (e.g., higher prevalence of smoking and physical activity in men and of obesity in women in most populations. Smoking and physical activity were associated with low SES in most populations. The associations of SES with obesity, hypertension, cholesterol and elevated blood glucose differed by population, sex, and SES indicator. For example, the prevalence of elevated blood glucose tended to be associated with low education, but not with wealth, in Seychelles and USA. The association of SES with obesity and cholesterol was direct in some populations but inverse in others. Conclusions In conclusion, the distribution of NCD-RFs was socially patterned in these populations at different stages of the epidemiological transition, but associations between SES and NCD-RFs differed substantially according to risk factor, population, sex, and SES indicator. These findings emphasize the need to assess and integrate the social patterning of NCD-RFs in NCD prevention and control programs in LMICs.

Cardiovascular epidemiological transition in a rural habitat of Nigeria: the case of mangu local government area.

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Okeahialam, B N; Ogbonna, C; Otokwula, A E; Joseph, D E; Chuhwak, E K; Isiguzoro, I O

2012-01-01

Epidemiological transition is at various stages in different places. The true situation in sub-Saharan Africa (SSA) is largely unknown. Having studied this rural habitat 17 years ago, we returned there to study several cardiovascular disease (CVD) risk factors to see if any change had occurred. The communities studied in 1991 as part of the national CVD survey were returned to in 2008 and re-studied descriptively in a cross-sectional manner. All adults 15 years and above, apart from demographic and personal data had blood pressure (BP) and some blood indices determined. Over the period, some changes occurred. The mean (SD) age increased from 34.1(16.9) to 45.5(18.2) years suggesting an ageing population. More people in 2008 than 1991 lived most of their last 5 years in the urban areas suggesting some influence of urbanisation. Significantly fewer people smoked and drank after 17 years. However mean (SD) of Body Mass Index rose [20.7(2.8) to 23.7(4.5) kg/m²], as well as SBP and DBP. Prevalence of hypertension rose from 7.4% to 20.9%. Both total and HDL cholesterol rose, although atherogenic index dropped. Mean (SD) blood sugar interestingly dropped from 5.0(2.9) to 4.6(1.0) mmol/l. Epidemiological transition is evident in this rural SSA habitat, and proactive steps to stem the tide and curb the consequences of CVD should be instituted.

Eat dirt and avoid atopy: the hygiene hypothesis revisited.

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Patki, Anil

2007-01-01

The explosive rise in the incidence of atopic diseases in the Western developed countries can be explained on the basis of the so-called "hygiene hypothesis". In short, it attributes the rising incidence of atopic dermatitis to reduced exposure to various childhood infections and bacterial endotoxins. Reduced exposure to dirt in the clean environment results in a skewed development of the immune system which results in an abnormal allergic response to various environmental allergens which are otherwise innocuous. This article reviews the historical aspects, epidemiological and immunological basis of the hygiene hypothesis and implications for Indian conditions.

La hipótesis de la compresión de la morbilidad: un ejemplo de desarrollo teórico en epidemiología The hypothesis of the compression of morbidity: an example of theoretical development in epidemiology

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Sergio López-Moreno

1998-09-01

Full Text Available En este documento se revisa la hipótesis de la compresión de la morbilidad, propuesta por James Fries en 1980, como un ejemplo de elaboración teórica en el campo de la epidemiología. Se presentan inicialmente algunos rasgos fundamentales de las teorías científicas y se hace un recuento histórico de los modelos causales más importantes que ha utilizado la epidemiología. Posteriormente, se presentan los fundamentos de la hipótesis de la compresión de la morbilidad, y se examinan sus posibilidades y limitaciones actuales, así como sus implicaciones epistemológicas con base en la teoría estructuralista. Se concluye que si el modelo de la compresión de la morbilidad fuera correcto, tendría una enorme capacidad para describir, explicar y predecir la salud y la enfermedad en las poblaciones humanas; por lo tanto, el desarrollo sistemático de este tipo de propuestas tiene una extraordinaria importancia para la salud pública.In this paper we review a hypothesis put forth in 1980 by James Fries under the name of the compression of morbidity, as an example of theoretical development in the field of epidemiology. Initially we discuss some of the essential features of scientific theories and make a historical account of the most important causal models that epidemiology has embraced. Then, the basis for proposing that a compression of the morbidity is taking place are described focusing on its advantages and limitations when it is analyzed from the point of view of structuralism. Finally, we conclude that, to the extent that they are correct, models of this kind have the potential of describing and predicting the evolution of human health; hence, their systematic development entails an extraordinary importance for public health.

Alzheimer's disease: the amyloid hypothesis and the Inverse Warburg effect

KAUST Repository

Demetrius, Lloyd A.; Magistretti, Pierre J.; Pellerin, Luc

2015-01-01

Epidemiological and biochemical studies show that the sporadic forms of Alzheimer's disease (AD) are characterized by the following hallmarks: (a) An exponential increase with age; (b) Selective neuronal vulnerability; (c) Inverse cancer comorbidity. The present article appeals to these hallmarks to evaluate and contrast two competing models of AD: the amyloid hypothesis (a neuron-centric mechanism) and the Inverse Warburg hypothesis (a neuron-astrocytic mechanism). We show that these three hallmarks of AD conflict with the amyloid hypothesis, but are consistent with the Inverse Warburg hypothesis, a bioenergetic model which postulates that AD is the result of a cascade of three events—mitochondrial dysregulation, metabolic reprogramming (the Inverse Warburg effect), and natural selection. We also provide an explanation for the failures of the clinical trials based on amyloid immunization, and we propose a new class of therapeutic strategies consistent with the neuroenergetic selection model.

Alzheimer's disease: the amyloid hypothesis and the Inverse Warburg effect

KAUST Repository

Demetrius, Lloyd A.

2015-01-14

Epidemiological and biochemical studies show that the sporadic forms of Alzheimer\\'s disease (AD) are characterized by the following hallmarks: (a) An exponential increase with age; (b) Selective neuronal vulnerability; (c) Inverse cancer comorbidity. The present article appeals to these hallmarks to evaluate and contrast two competing models of AD: the amyloid hypothesis (a neuron-centric mechanism) and the Inverse Warburg hypothesis (a neuron-astrocytic mechanism). We show that these three hallmarks of AD conflict with the amyloid hypothesis, but are consistent with the Inverse Warburg hypothesis, a bioenergetic model which postulates that AD is the result of a cascade of three events—mitochondrial dysregulation, metabolic reprogramming (the Inverse Warburg effect), and natural selection. We also provide an explanation for the failures of the clinical trials based on amyloid immunization, and we propose a new class of therapeutic strategies consistent with the neuroenergetic selection model.

Salmonella epidemiology: A whirlwind of change.

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Besser, John M

2018-05-01

The field of infectious disease epidemiology for Salmonella and other enteric pathogens is undergoing some of the most profound changes since the time of Kauffman and White. Rapid advances in "big data" technologies such as genomics and metagenomics are making it possible to monitor and control salmonellosis in new and exciting ways. Epidemiological methods are becoming increasingly robust through the routine use of standardized hypothesis-generating questionnaires, iterative open-ended interviewing, informational trace-backs and new modeling techniques for describing the attribution of disease to food sources. In addition, Salmonella epidemiology is facing important challenges and new opportunities due to the rapid adoption of culture independent diagnostic test panels by clinical laboratories. Where is this unprecedented wave of change taking us? This chapter will examine emerging trends in Salmonella epidemiology, and take a peek into the not-so-distant future. Published by Elsevier Ltd.

Essential evidence for guiding health system priorities and policies: anticipating epidemiological transition in Africa.

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Byass, Peter; de Savigny, Don; Lopez, Alan D

2014-01-01

Despite indications that infection-related mortality in sub-Saharan Africa may be decreasing and the burden of non-communicable diseases increasing, the overwhelming reality is that health information systems across most of sub-Saharan Africa remain too weak to track epidemiological transition in a meaningful and effective way. We propose a minimum dataset as the basis of a functional health information system in countries where health information is lacking. This would involve continuous monitoring of cause-specific mortality through routine civil registration, regular documentation of exposure to leading risk factors, and monitoring effective coverage of key preventive and curative interventions in the health sector. Consideration must be given as to how these minimum data requirements can be effectively integrated within national health information systems, what methods and tools are needed, and ensuring that ethical and political issues are addressed. A more strategic approach to health information systems in sub-Saharan African countries, along these lines, is essential if epidemiological changes are to be tracked effectively for the benefit of local health planners and policy makers. African countries have a unique opportunity to capitalize on modern information and communications technology in order to achieve this. Methodological standards need to be established and political momentum fostered so that the African continent's health status can be reliably tracked. This will greatly strengthen the evidence base for health policies and facilitate the effective delivery of services.

Essential evidence for guiding health system priorities and policies: anticipating epidemiological transition in Africa

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Peter Byass

2014-05-01

Full Text Available Background: Despite indications that infection-related mortality in sub-Saharan Africa may be decreasing and the burden of non-communicable diseases increasing, the overwhelming reality is that health information systems across most of sub-Saharan Africa remain too weak to track epidemiological transition in a meaningful and effective way. Proposals: We propose a minimum dataset as the basis of a functional health information system in countries where health information is lacking. This would involve continuous monitoring of cause-specific mortality through routine civil registration, regular documentation of exposure to leading risk factors, and monitoring effective coverage of key preventive and curative interventions in the health sector. Consideration must be given as to how these minimum data requirements can be effectively integrated within national health information systems, what methods and tools are needed, and ensuring that ethical and political issues are addressed. A more strategic approach to health information systems in sub-Saharan African countries, along these lines, is essential if epidemiological changes are to be tracked effectively for the benefit of local health planners and policy makers. Conclusion: African countries have a unique opportunity to capitalize on modern information and communications technology in order to achieve this. Methodological standards need to be established and political momentum fostered so that the African continent's health status can be reliably tracked. This will greatly strengthen the evidence base for health policies and facilitate the effective delivery of services.

Convergence of the epidemiology and pathology of COPD

DEFF Research Database (Denmark)

Vestbo, Jørgen; Hogg, J C

2006-01-01

The epidemiology of chronic obstructive pulmonary disease (COPD) has been dominated by one hypothesis stating that cigarette smoking and chronic bronchitis were the key to pathogenesis and another that asthma, chronic bronchitis, and even emphysema are related to different expressions of a primary...

The Sit-and-Wait Hypothesis in Bacterial Pathogens: A Theoretical Study of Durability and Virulence

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Liang Wang

2017-11-01

Full Text Available The intriguing sit-and-wait hypothesis predicts that bacterial durability in the external environment is positively correlated with their virulence. Since its first proposal in 1987, the hypothesis has been spurring debates in terms of its validity in the field of bacterial virulence. As a special case of the vector-borne transmission versus virulence tradeoff, where vector is now replaced by environmental longevity, there are only sporadic studies over the last three decades showing that environmental durability is possibly linked with virulence. However, no systematic study of these works is currently available and epidemiological analysis has not been updated for the sit-and-wait hypothesis since the publication of Walther and Ewald’s (2004 review. In this article, we put experimental evidence, epidemiological data and theoretical analysis together to support the sit-and-wait hypothesis. According to the epidemiological data in terms of gain and loss of virulence (+/- and durability (+/- phenotypes, we classify bacteria into four groups, which are: sit-and-wait pathogens (++, vector-borne pathogens (+-, obligate-intracellular bacteria (--, and free-living bacteria (-+. After that, we dive into the abundant bacterial proteomic data with the assistance of bioinformatics techniques in order to investigate the two factors at molecular level thanks to the fast development of high-throughput sequencing technology. Sequences of durability-related genes sourced from Gene Ontology and UniProt databases and virulence factors collected from Virulence Factor Database are used to search 20 corresponding bacterial proteomes in batch mode for homologous sequences via the HMMER software package. Statistical analysis only identified a modest, and not statistically significant correlation between mortality and survival time for eight non-vector-borne bacteria with sit-and-wait potentials. Meanwhile, through between-group comparisons, bacteria with higher

Genesis of Preeclampsia: An Epidemiological Approach

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Salvador-Moysén, Jaime; Martínez-López, Yolanda; Ramírez-Aranda, José M.; Aguilar-Durán, Marisela; Terrones-González, Alberto

2012-01-01

There are analyzed some of the main aspects related to the causality of preeclampsia, privileging two types of models: the clinic model and the epidemiologic model, first one represented by the hypothesis of the reduced placental perfusion and the second one considering the epidemiologic findings related to the high levels of psychosocial stress and its association with preeclampsia. It is reasoned out the relevance of raising the causality of the disease from an interdisciplinary perspective, integrating the valuable information generated from both types, clinical and epidemiologic, and finally a tentative explanatory model of preeclampsia is proposed, the subclinical and sociocultural aspects that predispose and trigger the disease are emphasized making aspects to stand out: the importance of reduced placental perfusion as an indicator of individual risk, and the high levels of physiological stress, as a result of the unfavorable conditions of the psychosocial surroundings (indicator of population risk) of the pregnant women. PMID:22462008

Epidemiology, hunger and development

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Paulo H. Battaglin Machado

2008-06-01

Full Text Available Understanding the relationship between epidemiology and food security implies in disclosing famine causes, the way it is distributed in the society and to which extent it affects the populations. Building up from that perspective, this paper attempts to understand the famine logic throughout the various transitions accomplished in the past decades: epidemiologic, demographic, risk, nutritional and development. The reflexes of the demographic transition that took place in Brazil in the XXth century are related to the population nutritional status standard changes, that is, they shifted from malnutrition high prevalence to a significant increase in obesity. However, the paradox of this situation is due to the fact that most risk factors that bring about diseases of the modern world come from the “excess”, while millions die around the globe because of “deprivation”. The food production alone does not ensure its equitable distribution among the various groups of the society. The access alone does not lead to quality. The choices are made individually, but life style options imply in a set of correlations that go from economy to culture. It means that this field has a collective basis and encompasses environment and development.

Early life exposure to antibiotics and the risk of childhood allergic diseases: an update from the perspective of the hygiene hypothesis.

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Kuo, Chang-Hung; Kuo, Hsuan-Fu; Huang, Ching-Hua; Yang, San-Nan; Lee, Min-Sheng; Hung, Chih-Hsing

2013-10-01

The prevalence of allergic diseases has been growing rapidly in industrial countries during recent decades. It is postulated that growing up with less microbial exposure may render the immune system susceptible to a T helper type 2 (Th2)-predominant allergic response-also known as the hygiene hypothesis. This review delineates recent epidemiological and experimental evidence for the hygiene hypothesis, and integrates this hypothesis into the association between early life exposure to antibiotics and the development of allergic diseases and asthma. Several retrospective or prospective epidemiological studies reveal that early exposure to antibiotics may be positively associated with the development of allergic diseases and asthma. However, the conclusion is inconsistent. Experimental studies show that antibiotics may induce the Th2-skewed response by suppressing the T helper type 1 (Th1) response through inhibition of Th1 cytokines and disruption of the natural course of infection, or by disturbing the microflora of the gastrointestinal (GI) tract and therefore jeopardizing the establishment of oral tolerance and regulatory T cell immune responses. The hygiene hypothesis may not be the only explanation for the rapid increase in the prevalence of allergic diseases and asthma. Further epidemiological and experimental studies addressing the issue of the impact of environmental factors on the development of allergic diseases and the underlying mechanisms may unveil novel strategies for the prevention and treatment of allergic diseases in the future. Copyright © 2013. Published by Elsevier B.V.

[Dilemma of null hypothesis in ecological hypothesis's experiment test.

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Li, Ji

2016-06-01

Experimental test is one of the major test methods of ecological hypothesis, though there are many arguments due to null hypothesis. Quinn and Dunham (1983) analyzed the hypothesis deduction model from Platt (1964) and thus stated that there is no null hypothesis in ecology that can be strictly tested by experiments. Fisher's falsificationism and Neyman-Pearson (N-P)'s non-decisivity inhibit statistical null hypothesis from being strictly tested. Moreover, since the null hypothesis H 0 (α=1, β=0) and alternative hypothesis H 1 '(α'=1, β'=0) in ecological progresses are diffe-rent from classic physics, the ecological null hypothesis can neither be strictly tested experimentally. These dilemmas of null hypothesis could be relieved via the reduction of P value, careful selection of null hypothesis, non-centralization of non-null hypothesis, and two-tailed test. However, the statistical null hypothesis significance testing (NHST) should not to be equivalent to the causality logistical test in ecological hypothesis. Hence, the findings and conclusions about methodological studies and experimental tests based on NHST are not always logically reliable.

Tests of the planetary hypothesis for PTFO 8-8695b

DEFF Research Database (Denmark)

Yu, Liang; Winn, Joshua N.; Gillon, Michaël

2015-01-01

The T Tauri star PTFO 8-8695 exhibits periodic fading events that have been interpreted as the transits of a giant planet on a precessing orbit. Here we present three tests of the planet hypothesis. First, we sought evidence for the secular changes in light-curve morphology that are predicted...... planetary orbit. Our spectroscopy also revealed strong, time-variable, high-velocity H{\\alpha} and Ca H & K emission features. All these observations cast doubt on the planetary hypothesis, and suggest instead that the fading events represent starspots, eclipses by circumstellar dust, or occultations...

Pinocchio: Geppetto's transitional object

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Gabriele Zeloni

2015-01-01

Full Text Available The literature has been considered by Freud and others after him, a form of unaware exploration of mind that can leads to discoveries similar to psychoanalysis’s discoveries. From this perspective, the author puts forward the following hypothesis: Pinocchio is a puppet who comes to life and is therefore, from a child's perception, a transitional object according to Winnicott. Consequently Geppetto is nothing more than the involuntary representation of any child interacting with the transitional object. The author explains the results of the analysis of the text in support of the hypothesis and reflects on the impact of The adventure of Pinocchio on the reader.

Eigenstate Phase Transitions

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Zhao, Bo

Phase transitions are one of the most exciting physical phenomena ever discovered. The understanding of phase transitions has long been of interest. Recently eigenstate phase transitions have been discovered and studied; they are drastically different from traditional thermal phase transitions. In eigenstate phase transitions, a sharp change is exhibited in properties of the many-body eigenstates of the Hamiltonian of a quantum system, but not the thermal equilibrium properties of the same system. In this thesis, we study two different types of eigenstate phase transitions. The first is the eigenstate phase transition within the ferromagnetic phase of an infinite-range spin model. By studying the interplay of the eigenstate thermalization hypothesis and Ising symmetry breaking, we find two eigenstate phase transitions within the ferromagnetic phase: In the lowest-temperature phase the magnetization can macroscopically oscillate by quantum tunneling between up and down. The relaxation of the magnetization is always overdamped in the remainder of the ferromagnetic phase, which is further divided into phases where the system thermally activates itself over the barrier between the up and down states, and where it quantum tunnels. The second is the many-body localization phase transition. The eigenstates on one side of the transition obey the eigenstate thermalization hypothesis; the eigenstates on the other side are many-body localized, and thus thermal equilibrium need not be achieved for an initial state even after evolving for an arbitrary long time. We study this many-body localization phase transition in the strong disorder renormalization group framework. After setting up a set of coarse-graining rules for a general one dimensional chain, we get a simple "toy model'' and obtain an almost purely analytical solution to the infinite-randomness critical fixed point renormalization group equation. We also get an estimate of the correlation length critical exponent nu

The epidemiologic transition of thalassemia and associated hemoglobinopathies in southern Taiwan.

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Wang, Hui-Ching; Hsieh, Li-Ling; Liu, Yi-Chang; Hsiao, Hui-Hua; Lin, Shu-Kai; Tsai, Wen-Chan; Liu, Ta-Chih

2017-02-01

Since 1993, following the National Thalassemia Major Prevention Program and an increase in immigration and interracial marriages, especially in southern Taiwan, the distribution of hemoglobinopathies may have changed. This study investigates the epidemiologic transition of hemoglobinopathies. We analyzed 1870 specimens collected between 2003 and 2012 in southern Taiwan, used gap-polymerase chain reaction and PCR-restriction fragment length polymorphism-based methods, and confirmed genotypes of hemoglobinopathies by DNA sequencing. We found a 91% reduction in the incidence of thalassemia major compared with samples from between 1986 and 1995. The most common genotypes of α-thalassemia and α Hb variants were the SEA type (69.4%) and Hb Quong Sze (1.54%). The most common genotypes of β-thalassemia and β Hb variants were IVS-II-654 (46.2%) and Hb E (2.2%), respectively. Compared with studies performed in different areas of and time intervals in Taiwan, a higher prevalence of -α 3.7 , Hb Quong Sze, and Hb E and a lower prevalence of the SEA type were found in this study. However, the SEA type remained the most common genotype observed. In addition, an increasing number of cases with an -α 3.7 type carrier, Hb Quong Sze carrier, and G γ (A γ δβ)° were identified following a peak of interracial marriages between 2003 and 2005, reflecting a regional difference and the impact of interracial marriage. In conclusion, global migration and international marriage have changed the distribution of hemoglobinopathies in Taiwan. A more comprehensive prenatal screening for new immigrants with a longer follow-up is warranted.

Hypothesis analysis methods, hypothesis analysis devices, and articles of manufacture

Science.gov (United States)

Sanfilippo, Antonio P [Richland, WA; Cowell, Andrew J [Kennewick, WA; Gregory, Michelle L [Richland, WA; Baddeley, Robert L [Richland, WA; Paulson, Patrick R [Pasco, WA; Tratz, Stephen C [Richland, WA; Hohimer, Ryan E [West Richland, WA

2012-03-20

Hypothesis analysis methods, hypothesis analysis devices, and articles of manufacture are described according to some aspects. In one aspect, a hypothesis analysis method includes providing a hypothesis, providing an indicator which at least one of supports and refutes the hypothesis, using the indicator, associating evidence with the hypothesis, weighting the association of the evidence with the hypothesis, and using the weighting, providing information regarding the accuracy of the hypothesis.

Epidemiology and risk assessment for radiation

International Nuclear Information System (INIS)

Badwe, R.A.

2014-01-01

The hazard and exposures from radiation are known with reasonable accuracy. However, at 'low levels' uncertainty persists as to whether the dose response relationship is linear and whether there is a dose threshold, below which there is no risk. Some have proposed that 'low' exposures to radiation may be beneficial, a hypothesis referred to as 'hormesis'. Over recent decades, various expert groups have adopted linear no-threshold dose-response models for radiation and cancer, based on review of epidemiological and biological evidence. The unexpected epidemic of thyroid cancer among children following the Chernobyl disaster was noticed. The research with epidemiological data and knowledge of the radionuclides to which the children were exposed is needed. Currently a debate concerning potential risks of high frequency electromagnetic radiation from mobile phones illustrates another need for further research

Implications of infectious diseases and the adrenal hypothesis for the etiology of childhood acute lymphoblastic leukemia

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F. Azevedo-Silva

2010-03-01

Full Text Available Acute leukemia is the most frequent cancer in children. Recently, a new hypothesis was proposed for the pathogenesis of childhood acute lymphoblastic leukemia (ALL. The so-called "adrenal hypothesis" emphasized the role of endogenous cortisol in the etiology of B-cell precursor ALL. The incidence peak of ALL in children between 3 to 5 years of age has been well documented and is consistent with this view. The adrenal hypothesis proposes that the risk of childhood B-cell precursor ALL is reduced when early childhood infections induce qualitative and quantitative changes in the hypothalamus-pituitary-adrenal axis. It suggests that the increased plasma cortisol levels would be sufficient to eliminate all clonal leukemic cells originating during fetal life. Because Brazil is a continental and tropical country, the exposure to infections is diversified with endemic viral and regionally non-viral infections, with some characteristics that support the recent adrenal hypothesis. Here we discuss this new hypothesis in terms of data from epidemiological studies and the possible implications of the diversity of infections occurring in Brazilian children.

Local health department epidemiologic capacity: a stratified cross-sectional assessment describing the quantity, education, training, and perceived competencies of epidemiologic staff.

Science.gov (United States)

O'Keefe, Kaitlin A; Shafir, Shira C; Shoaf, Kimberley I

2013-01-01

Local health departments (LHDs) must have sufficient numbers of staff functioning in an epidemiologic role with proper education, training, and skills to protect the health of communities they serve. This pilot study was designed to describe the composition, training, and competency level of LHD staff and examine the hypothesis that potential disparities exist between LHDs serving different sized populations. Cross-sectional surveys were conducted with directors and epidemiologic staff from a sample of 100 LHDs serving jurisdictions of varied sizes. Questionnaires included inquiries regarding staff composition, education, training, and measures of competency modeled on previously conducted studies by the Council of State and Territorial Epidemiologists. Number of epidemiologic staff, academic degree distribution, epidemiologic training, and both director and staff confidence in task competencies were calculated for each LHD size strata. Disparities in measurements were observed in LHDs serving different sized populations. LHDs serving small populations reported a smaller average number of epidemiologic staff than those serving larger jurisdictions. As size of population served increased, percentages of staff and directors holding bachelors' and masters' degrees increased, while those holding RN degrees decreased. A higher degree of perceived competency of staff in most task categories was reported in LHDs serving larger populations. LHDs serving smaller populations reported fewer epidemiologic staff, therefore might benefit from additional resources. Differences observed in staff education, training, and competencies suggest that enhanced epidemiologic training might be particularly needed in LHDs serving smaller populations. RESULTS can be used as a baseline for future research aimed at identifying areas where training and personnel resources might be particularly needed to increase the capabilities of LHDs.

La transición epidemiológica de las y los adolescentes en México The epidemiologic transition among adolescents in Mexico

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José Ignacio Santos-Preciado

2003-01-01

performed in order to asses the impact of the epidemiologic transition on the availability and priority of health services for adolescents. The Omran epidemiologic model was used to classify the demographic, social and economic characteristics of Mexican adolescents in efforts to define their impact on the epidemiologic transition of this age group. RESULTS: Demographic data are presented in the perspective of the epidemiologic transition which permit us to make inferences on the social conditions , growth patterns and health needs of this age group in Mexico. Data are presented regarding the demand and availability of health services, the impact of education and employment opportunities and the role of family and the economy on their well being. Other important aspects presented include the role of education on the sexual and reproductive health of adolescents and the threat of the AIDS pandemic in this age group. CONCLUSIONS: These findings reveal a sequence of variables that can no longer be addressed in the traditional problem oriented approach and strongly suggest a need to profile the health needs of adolescents in an integrated, holistic fashion with emphasis in health promotion and healthy life styles to favor their integral, just and equitable development, and also help focus the societal response in an integrated manner.

Beyond the hypothesis: Theory's role in the genesis, opposition, and pursuit of the Higgs boson

Science.gov (United States)

Wells, James D.

2018-05-01

The centrally recognized theoretical achievement that enabled the Higgs boson discovery in 2012 was the hypothesis of its existence, made by Peter Higgs in 1964. Nevertheless, there is a significant body of comparably important theoretical work prior to and after the Higgs boson hypothesis. In this article we present an additional perspective of how crucial theory work was to the genesis of the Higgs boson hypothesis, especially emphasizing its roots in Landau's theory of phase transitions and subsequent theoretical work on superconductivity. A detailed description is then given of the opposition to the Higgs boson hypothesis by many researchers, giving evidence to its speculative nature. And finally, it is discussed the importance of theory work in the decades after the hypothesis in order to make possible the experimental discovery of the Higgs boson.

The hygiene hypothesis in autoimmunity: the role of pathogens and commensals.

Science.gov (United States)

Bach, Jean-François

2018-02-01

The incidence of autoimmune diseases has been steadily rising. Concomitantly, the incidence of most infectious diseases has declined. This observation gave rise to the hygiene hypothesis, which postulates that a reduction in the frequency of infections contributes directly to the increase in the frequency of autoimmune and allergic diseases. This hypothesis is supported by robust epidemiological data, but the underlying mechanisms are unclear. Pathogens are known to be important, as autoimmune disease is prevented in various experimental models by infection with different bacteria, viruses and parasites. Gut commensal bacteria also play an important role: dysbiosis of the gut flora is observed in patients with autoimmune diseases, although the causal relationship with the occurrence of autoimmune diseases has not been established. Both pathogens and commensals act by stimulating immunoregulatory pathways. Here, I discuss the importance of innate immune receptors, in particular Toll-like receptors, in mediating the protective effect of pathogens and commensals on autoimmunity.

The urban health transition hypothesis: empirical evidence of an avian influenza Kuznets curve in Vietnam?

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Spencer, James Herbert

2013-04-01

The literature on development has focused on the concept of transition in understanding the emergent challenges facing poor but rapidly developing countries. Scholars have focused extensively on the health and urban transitions associated with this change and, in particular, its use for understanding emerging infectious diseases. However, few have developed explicit empirical measures to quantify the extent to which a transitions focus is useful for theory, policy, and practice. Using open source data on avian influenza in 2004 and 2005 and the Vietnam Census of Population and Housing, this paper introduces the Kuznets curve as a tool for empirically estimating transition and disease. Findings suggest that the Kuznets curve is a viable tool for empirically assessing the role of transitional dynamics in the emergence of new infectious diseases.

[Eco-epidemiology: towards epidemiology of complexity].

Science.gov (United States)

Bizouarn, Philippe

2016-05-01

In order to solve public health problems posed by the epidemiology of risk factors centered on the individual and neglecting the causal processes linking the risk factors with the health outcomes, Mervyn Susser proposed a multilevel epidemiology called eco-epidemiology, addressing the interdependence of individuals and their connection with molecular, individual, societal, environmental levels of organization participating in the causal disease processes. The aim of this epidemiology is to integrate more than a level of organization in design, analysis and interpretation of health problems. After presenting the main criticisms of risk-factor epidemiology focused on the individual, we will try to show how eco-epidemiology and its development could help to understand the need for a broader and integrative epidemiology, in which studies designed to identify risk factors would be balanced by studies designed to answer other questions equally vital to public health. © 2016 médecine/sciences – Inserm.

The epidemiological transition in Antananarivo, Madagascar: an assessment based on death registers (1900–2012

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Bruno Masquelier

2014-05-01

Full Text Available Background: Madagascar today has one of the highest life expectancies in sub-Saharan Africa, despite being among the poorest countries in the continent. There are relatively few detailed accounts of the epidemiological transition in this country due to the lack of a comprehensive death registration system at the national level. However, in Madagascar's capital city, death registration was established around the start of the 20th century and is now considered virtually complete. Objective: We provide an overview of trends in all-cause and cause-specific mortality in Antananarivo to document the timing and pace of the mortality decline and the changes in the cause-of-death structure. Design: Death registers covering the period 1976–2012 were digitized and the population at risk of dying was estimated from available censuses and surveys. Trends for the period 1900–1976 were partly reconstructed from published sources. Results: The crude death rate stagnated around 30‰ until the 1940s in Antananarivo. Mortality declined rapidly after the World War II and then resurged again in the 1980s as a result of the re-emergence of malaria and the collapse of Madagascar's economy. Over the past 30 years, impressive gains in life expectancy have been registered thanks to the unabated decline in child mortality, despite political instability, a lasting economic crisis and the persistence of high rates of chronic malnutrition. Progress in adult survival has been more modest because reductions in infectious diseases and diseases of the respiratory system have been partly offset by increases in cardiovascular diseases, neoplasms, and other diseases, particularly at age 50 years and over. Conclusions: The transition in Antananarivo has been protracted and largely dependent on anti-microbial and anti-parasitic medicine. The capital city now faces a double burden of communicable and non-communicable diseases. The ongoing registration of deaths in the capital

Hypothesis Designs for Three-Hypothesis Test Problems

OpenAIRE

Yan Li; Xiaolong Pu

2010-01-01

As a helpful guide for applications, the alternative hypotheses of the three-hypothesis test problems are designed under the required error probabilities and average sample number in this paper. The asymptotic formulas and the proposed numerical quadrature formulas are adopted, respectively, to obtain the hypothesis designs and the corresponding sequential test schemes under the Koopman-Darmois distributions. The example of the normal mean test shows that our methods are qu...

Profesi Epidemiologi

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Buchari Lapau

2011-01-01

Full Text Available Makalah ini pertama kali menjelaskan perlu adanya profesi kesehatan masyarakat dalam rangka pembangunan kesehatan. Lalu dijelaskan apa profesi itu dan standar keberadaan profesi, atas dasar mana dapat ditetapkan bahwa pelayanan epidemiologi merupakan salah satu profesi. Dalam rangka pembinaan profesi kesehatan masyarakat, IAKMI dan APTKMI telah membentuk Majelis Kolegium Kesehatan Masyarakat Indonesia (MKKMI yang terdiri atas 8 kolegium antara lain Kolegium Epidemiologi, yang telah menyusun Standar Profesi Epidemiologi yang terdiri atas beberapa standar. Masing-masing standar dijelaskan mulai dari kurikulum, standar pelayanan epidmiologi, profil epidemiolog kesehatan, peran epidemiolog kesehatan, fungsi epidemiolog kesehatan, standar kompetensi epidemiologi, dan standar pendidikan profesi epidemiologi.

The obese gut microbiome across the epidemiologic transition

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Lara R. Dugas

2016-01-01

Full Text Available Abstract The obesity epidemic has emerged over the past few decades and is thought to be a result of both genetic and environmental factors. A newly identified factor, the gut microbiota, which is a bacterial ecosystem residing within the gastrointestinal tract of humans, has now been implicated in the obesity epidemic. Importantly, this bacterial community is impacted by external environmental factors through a variety of undefined mechanisms. We focus this review on how the external environment may impact the gut microbiota by considering, the host’s geographic location ‘human geography’, and behavioral factors (diet and physical activity. Moreover, we explore the relationship between the gut microbiota and obesity with these external factors. And finally, we highlight here how an epidemiologic model can be utilized to elucidate causal relationships between the gut microbiota and external environment independently and collectively, and how this will help further define this important new factor in the obesity epidemic.

Inflammation and the Two-Hit Hypothesis of Schizophrenia

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Feigenson, Keith A.; Kusnecov, Alex W.; Silverstein, Steven M.

2014-01-01

The high societal and individual cost of schizophrenia necessitates finding better, more effective treatment, diagnosis, and prevention strategies. One of the obstacles in this endeavor is the diverse set of etiologies that comprises schizophrenia. A substantial body of evidence has grown over the last few decades to suggest that schizophrenia is a heterogeneous syndrome with overlapping symptoms and etiologies. At the same time, an increasing number of clinical, epidemiological, and experimental studies have shown links between schizophrenia and inflammatory conditions. In this review, we analyze the literature on inflammation and schizophrenia, with a particular focus on comorbidity, biomarkers, and environmental insults. We then identify several mechanisms by which inflammation could influence the development of schizophrenia via the two-hit hypothesis. Lastly, we note the relevance of these findings to clinical applications in the diagnosis, prevention, and treatment of schizophrenia. PMID:24247023

Cholesterol as a Causative Factor in Alzheimer Disease: A Debatable Hypothesis

Science.gov (United States)

Wood, W. Gibson; Li, Ling; Müller, Walter E.; Eckert, Gunter P.

2014-01-01

High serum/plasma cholesterol levels have been suggested as a risk factor for Alzheimer disease (AD). Some reports, mostly retrospective epidemiological studies, have observed a decreased prevalence of AD in patients taking the cholesterol lowering drugs, statins. The strongest evidence causally linking cholesterol to AD is provided by experimental studies showing that adding/reducing cholesterol alters amyloid precursor protein (APP) and amyloid beta-protein (Aβ) levels. However, there are problems with the cholesterol-AD hypothesis. Cholesterol levels in serum/plasma and brain of AD patients do not support cholesterol as a causative factor in AD. Prospective studies on statins and AD have largely failed to show efficacy. Even the experimental data are open to interpretation given that it is well-established that modification of cholesterol levels has effects on multiple proteins, not only APP and Aβ. The purpose of this review, therefore, is to examine the above-mentioned issues and discuss the pros and cons of the cholesterol-AD hypothesis, and the involvement of other lipids in the mevalonate pathway, such as isoprenoids and oxysterols, in AD. PMID:24329875

Mortality in Catalonia in the context of the third, fourth and future phases of the epidemiological transition theory

Directory of Open Access Journals (Sweden)

2009-02-01

Full Text Available In the period 1960-2000, male and female life expectancy increased by 8,2 and 10,5 years, respectively, in Catalonia, one of Spain's Autonomous Regions, to one of the highest in the world. Initially, most gains were due to lower infant mortality, but as cardiovascular diseases declined this later shifted to advanced ages. Between the mid-1980s and early 1990s life expectancy improvements stagnated as the mortality risk from traffic accidents and HIV/AIDS in young adults increased. Both the age-delay in old-age mortality and the simultaneous influence of behaviour and life style reflect distinct aspects of the fourth stage of the epidemiological transition. This analysis quantifies the age and cause of death contributions to changes and sex-differences in life expectancy in Catalonia. It subsequently compares the most recent life table for women with the Duchene-Wunsch limited life table to estimate the potential gain in life expectancy when all deaths would be ageing-related and on which ages these improvements would fall.

Life Origination Hydrate Hypothesis (LOH-Hypothesis

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Victor Ostrovskii

2012-01-01

Full Text Available The paper develops the Life Origination Hydrate Hypothesis (LOH-hypothesis, according to which living-matter simplest elements (LMSEs, which are N-bases, riboses, nucleosides, nucleotides, DNA- and RNA-like molecules, amino-acids, and proto-cells repeatedly originated on the basis of thermodynamically controlled, natural, and inevitable processes governed by universal physical and chemical laws from CH4, niters, and phosphates under the Earth's surface or seabed within the crystal cavities of the honeycomb methane-hydrate structure at low temperatures; the chemical processes passed slowly through all successive chemical steps in the direction that is determined by a gradual decrease in the Gibbs free energy of reacting systems. The hypothesis formulation method is based on the thermodynamic directedness of natural movement and consists ofan attempt to mentally backtrack on the progression of nature and thus reveal principal milestones alongits route. The changes in Gibbs free energy are estimated for different steps of the living-matter origination process; special attention is paid to the processes of proto-cell formation. Just the occurrence of the gas-hydrate periodic honeycomb matrix filled with LMSEs almost completely in its final state accounts for size limitation in the DNA functional groups and the nonrandom location of N-bases in the DNA chains. The slowness of the low-temperature chemical transformations and their “thermodynamic front” guide the gross process of living matter origination and its successive steps. It is shown that the hypothesis is thermodynamically justified and testable and that many observed natural phenomena count in its favor.

Wastewater-based epidemiology, an analytical chemical approach for the investigation of human consumption of lifestyle chemicals

NARCIS (Netherlands)

Causanilles Llanes, A.

2018-01-01

The research presented in this thesis supports the hypothesis that wastewater-based epidemiology (WBE) approach can be used as an alternative and non-intrusive technique that provides information about a population’s health and lifestyle habits. The focus is in the essential role of analytical

Transit value capture coordination : case studies, best practices, and recommendations.

Science.gov (United States)

2015-02-17

This study is based on the hypothesis that coordination between transit capital planners, municipal taxation authorities, and private developers and stakeholders can be a benefit to transit capital projects that choose to use value capture as a fundi...

A double-integration hypothesis to explain ocean ecosystem response to climate forcing

Science.gov (United States)

Di Lorenzo, Emanuele; Ohman, Mark D.

2013-01-01

Long-term time series of marine ecological indicators often are characterized by large-amplitude state transitions that can persist for decades. Understanding the significance of these variations depends critically on the underlying hypotheses characterizing expected natural variability. Using a linear autoregressive model in combination with long-term zooplankton observations off the California coast, we show that cumulative integrations of white-noise atmospheric forcing can generate marine population responses that are characterized by strong transitions and prolonged apparent state changes. This model provides a baseline hypothesis for explaining ecosystem variability and for interpreting the significance of abrupt responses and climate change signatures in marine ecosystems. PMID:23341628

Difficulty in Assessing Quality of Life Outcomes in a Fluctuating Disease: A Hypothesis Based on Gastroparesis

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Vic Velanovich

2009-01-01

Full Text Available An underlying assumption of quality of life outcome research is that after some intervention a “steady-state” of quality of life is reached which can be identified as an endpoint, and, hence, the “outcome.” However, in some disease processes, no so such steady-state is reached. The hypothesis presented is that a disease process with a waxing and waning course will make it difficult to determine a quality of life endpoint. After clinical observation, a pilot study of patients with either diabetic or idiopathic gastroparesis with gastric neurostimulation their records were reviewed to identify the number of clinic visits, the number of clinic visits in which the patients were asymptomatic, much improved, improved, no change, worse, or much worse. These changes were defined as “transitions.” A “transition ratio” was calculated by dividing the number of transitions by the number of clinic visits. Preliminary results showed that of 32 patients, the median number of clinic encounters was 8 (1–35, and the median number of transitions 4 (0–22. The average transition ration was 0.56±0.31. In the case of gastroparesis, over half of all clinical encounters were associated with a transition. The implication of the hypothesis and preliminary finding suggests a difficulty to identify when the symptomatic endpoint was reached. Other methods to assess the effects of treatment in such a disease process are required to fully understand the effects of treatment on quality of life.

Current issues in ALS epidemiology: Variation of ALS occurrence between populations and physical activity as a risk factor.

Science.gov (United States)

Luna, J; Logroscino, G; Couratier, P; Marin, B

2017-05-01

Amyotrophic lateral sclerosis (ALS) is a rare neurodegenerative disease with a fatal outcome. This review aims to report key epidemiological features of ALS in relation to the hypothesis of variation between populations, to summarize environmental hypothesis and to highlight current issues that deserve much considerations. Epidemiological ALS studies have shown a variation of incidence, mortality and prevalence between geographical areas and different populations. These data could support the notion that genetic factors, especially populations' ancestries, along with environmental and lifestyle factors, play a significant role in the occurrence of the disease. To date, there is no strong evidence to confirm an association between a particular environmental factor and ALS. Physical activity (PA) has been extensively evaluated. Recent studies support with the best evidence level that PA in general population is not a risk factor for ALS. However, further research is needed to clarify the association of PA in some occupations and some athletic activities. Epidemiological research based on multicenter international collaboration is essential to provide new data on ALS especially in some regions of the world that are to date poorly represented in the ALS literature. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

[Popper and the problem of induction in epidemiology].

Science.gov (United States)

Banegas, J R; Rodríguez Artalejo, F; del Rey Calero, J

2000-01-01

In this article we are discussing a few of the contributions by the Austro-British philosopher Karl R. Popper, one of our most influential contemporary thinkers, whose epistemological and socio-political theories have also penetrated the sphere of epidemiology. We are focusing mainly on the so-called problem of induction. We sustain, in line with Popper, that the scientific method does not use inductive reasoning, but rather hypothetical-deductive reasoning. Although the movement from the data evaluating a hypothesis to a conclusion on the latter goes from the specific to the general, that is, in an inductive direction, the induction does not exist as a reasoning process or inference. That is, there is no method that enables us to infer or to verify hypotheses or theories (we cannot explore all of the possible situations to see whether the theory stands up), or even to render them very probable. Besides, scientists look for highly informative theories, not highly probable ones. What we actually do is to propose a hypothesis as a tentative solution to a problem, to confront the prediction deduced from the hypothesis with actual experience, and evaluate whether the hypothesis is rejected or not by the facts. As theories cannot be verified, we can only accept them if they withstand an attempt to reject them. Consequently, the test of a theory consists of criticism or a serious attempt at falsification, that is, the elimination of error within a theory, in order to reject it if it is false. The objective is, thus, the search for true theories. For this purpose, the scientific method uses a systematic set of methodological (not logical) rules, that is, decisions. These methodological rules or principles can be summed up in two: [symbol: see text]be inventive and critical!, that is, propose bold hypotheses and subject them to severe tests of experience. Logic plays its role mainly by allowing us to deduce from a hypothesis the predictions to be confronted with the facts

Mesenchymal-to-endothelial transition in Kaposi sarcoma: a histogenetic hypothesis based on a case series and literature review.

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Simona Gurzu

Full Text Available OBJECTIVES: Although several studies have been conducted regarding Kaposi sarcoma (KS, its histogenesis still remains to be elucidated. The aim of our study was to analyze the immunophenotype of Kaposi sarcoma and to present a hypothesis about the histogenesis of this tumor, based on a case series and a review of relevant literature. METHODS: In 15 cases of KSs diagnosed during 2000-2011, the clinicopathological features were correlated with the immunoexpression of c-Kit, SMA, CD34, CD31, vascular endothelial growth factor (VEGF, COX-2, c-KIT, smooth muscle antigen (SMA, and stem cell surface marker CD105. RESULTS: Both CD105 and c-KIT rate of the spindle-shaped tumor cell positivity increased in parallel to the pathological stage. All cases displayed CD105 and weak c-KIT positivity in the endothelial cells. SMA, VEGF, and COX-2 were focally expressed in all cases. CD34 marked both endothelium and spindle-shaped tumor cells. No c-KIT expression was noticed in KS of the internal organs. CONCLUSIONS: KS seems to be a variant of myofibroblastic tumors that originates from the viral modified pluripotent mesenchymal cells of the connective tissue transformed in spindle-shaped KS cells, followed by a mesenchymal-endothelial transition and a myofibroblastic-like differentiation. This paper mailnly showed that KS cannot be considered a pure vascular tumor.

Validity of the Generalized Brink-Axel Hypothesis in (238)Np.

Science.gov (United States)

Guttormsen, M; Larsen, A C; Görgen, A; Renstrøm, T; Siem, S; Tornyi, T G; Tveten, G M

2016-01-08

We analyze primary γ-ray spectra of the odd-odd (238)Np nucleus extracted from (237)Np(d,pγ)(238)Np coincidence data measured at the Oslo Cyclotron Laboratory. The primary γ spectra cover an excitation-energy region of 0≤E(I)≤5.4  MeV, and allow us to perform a detailed study of the γ-ray strength as a function of excitation energy. Hence, we can test the validity of the generalized Brink-Axel hypothesis, which, in its strictest form, claims no excitation-energy dependence on the γ strength. In this work, using the available high-quality (238)Np data, we show that the γ-ray strength function is to a very large extent independent of the initial and final states. Thus, for the first time, the generalized Brink-Axel hypothesis is experimentally verified for γ transitions between states in the quasicontinuum region, not only for specific collective resonances, but also for the full strength below the neutron separation energy. Based on our findings, the necessary criteria for the generalized Brink-Axel hypothesis to be fulfilled are outlined.

DEMOGRAPHIC POLICY AND THE ANALYSIS OF IRRETRIEVABLE LOSSES OF PUBLIC HEALTH BASED ON THE CONCEPT OF THE EPIDEMIOLOGICAL TRANSITION

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Юрий Аркадьевич Григорьев

2017-09-01

Full Text Available From the general positions of population dynamics, the demographic policy is considered, its regional features in the East of Russia are designated. It is necessary to consolidate the positive traditions of the moral and legal norms of the society and the harmonious personality development. It takes their long-term translation for the improvement of the person himself, his family-marriage relations to support the forms of demographic behavior aimed at the expanded population reproduction. The solution of the numerous tasks of the demographic policy presupposes further scientific (theoretical and applied studies of the features of the socio-demographic and medico-demographic development of the Russian regions. Particular attention should be paid to the analysis of the main characteristics of the epidemiological transition, where mortality, as well as birth rate, is one of the main characteristics of the population reproduction. This will make it possible to define more precisely the prediction of the value of irretrievable losses with endogenous and exogenous determination, to estimate on this basis the reserves of increasing life expectancy through the measures of demographic policy.

Epidemiología de campo y epidemiología social Field epidemiology and social epidemiology

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Javier Segura del Pozo

2006-03-01

Full Text Available Mediante la comparación de la epidemiología de campo y la epidemiología social, se pretende reflexionar sobre los imaginarios no explícitos que operan en ambos ámbitos, necesariamente convergentes, sobre los obstáculos de la práctica epidemiológica actual para alcanzar su función social y sobre la necesidad de cambiar las bases epistemológicas, metodológicas y prácticas que operan en la epidemiología, empezando por la formación del epidemiólogo de campo. La epidemiología de campo tiende a la acción sin marco teórico. La epidemiología social, por el contrario, tiende a los desarrollos teóricos (reflexión e investigación sobre los determinantes sociales alejados de la acción, debido a los limitantes para cambiar las políticas públicas. Otras diferencias se sitúan en el nivel de intervención (micro/macroespacios, el objeto de intervención (control del brote frente a control de las desigualdades y en la forma de articular la comunicación con la sociedad. Se asemejan en la preocupación por el método, la predominancia de una orientación positivista y condicionada por la estadística, aunque en proceso de cierta apertura epistemológica, la tensión experimentada entre relacionarse con un mundo virtual de bases de datos o con la sociedad real, su situación en la periferia del sistema político-social-institucional-profesional y por estar abocadas a la frustración profesional. Finalmente, se formulan 10 interrogantes a los epidemiólogos de campo sobre su práctica actual, a través de los cuales se podría evaluar si están realizando una epidemiología social, y se sugieren cambios para introducir en la formación y práctica del epidemiólogo.Comparing field epidemiology and social epidemiology, we pretend to think about the no explicit images and meanings operating in both necessary convergent fields, about the obstacles present in epidemiological practice to fulfil its social function and about the necessity of

Topological transitions in the theory of spacetime

International Nuclear Information System (INIS)

Konstantinov, M.Y.; Melnikov, V.N.

1986-01-01

Results of a realisation of the topological transitions hypothesis are presented. The basic difficulties in the construction of quantum topological transition theory are connected with a necessity to introduce a new non-local interaction defined on a space of topological states. So the general method of construction and study of topological transitions classical models is formulated as a necessary step towards a corresponding quantum description. Their local properties, including an asymptotic behaviour in the neighbourhood of the transition, are studied and applications to problems of gravitation and cosmology are given. The method used is shown to lead to a scalar-tensor theory of topological transitions. Different variants of this theory and its main features are discussed. (author)

More than genes: the advanced fetal programming hypothesis.

Science.gov (United States)

Hocher, Berthold

2014-10-01

Many lines of data, initial epidemiologic studies as well as subsequent extensive experimental studies, indicate that early-life events play a powerful role in influencing later suceptibility to certain chronic diseases. Such events might be over- or undernutrition, exposure to environmental toxins, but also changes in hormones, in particular stress hormones. Typically, those events are triggered by the environmental challenges of the mother. However, recent studies have shown that paternal environmental or nutritional factors affect the phenotype of the offspring as well. The maternal and paternal environmental factors act on the phenotype of the offspring via epigenetic modification of its genome. The advanced fetal programming hypothesis proposes an additional non-environmentally driven mechanism: maternal and also paternal genes may influence the maturating sperm, the oocyte, and later the embryo/fetus, leading to their epigenetic alteration. Thus, the observed phenotype of the offspring may be altered by maternal/paternal genes independent of the fetal genome. Meanwhile, several independent association studies in humans dealing with metabolic and neurological traits also suggest that maternal genes might affect the offspring phenotype independent of the transmission of that particular gene to the offspring. Considering the implications of this hypothesis, some conclusions drawn from transgenic or knockout animal models and based on the causality between a genetic alteration and a phenotype, need to be challenged. Possible implications for the development, diagnostic and therapy of human genetic diseases have to be investigated. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Epidemiological studies in mucus hypersecretion

DEFF Research Database (Denmark)

Vestbo, Jørgen

2002-01-01

Respiratory mucus in epidemiology has mainly been studied using standardized questionnaires including questions on cough and phlegm. In chronic obstructive pulmonary disease (COPD) much controversy exists regarding the importance of mucus hypersecretion. From being the key element in the 'British...... hypothesis' it was reduced to being an innocent disorder in the 1980s but is now again recognized as a potential risk factor for an accelerated loss of lung function. Whereas early studies in mainly occupational cohorts showed no effect of chronic mucus hypersecretion on decline in lung function......, such an effect has been shown in subsequent studies on general population samples. Chronic mucus hypersecretion also increases risk of hospital admission which may be due to an increased risk of lower respiratory tract infection. In severe COPD this may explain the increased mortality associated...

Quantifying the limits of transition state theory in enzymatic catalysis.

Science.gov (United States)

Zinovjev, Kirill; Tuñón, Iñaki

2017-11-21

While being one of the most popular reaction rate theories, the applicability of transition state theory to the study of enzymatic reactions has been often challenged. The complex dynamic nature of the protein environment raised the question about the validity of the nonrecrossing hypothesis, a cornerstone in this theory. We present a computational strategy to quantify the error associated to transition state theory from the number of recrossings observed at the equicommittor, which is the best possible dividing surface. Application of a direct multidimensional transition state optimization to the hydride transfer step in human dihydrofolate reductase shows that both the participation of the protein degrees of freedom in the reaction coordinate and the error associated to the nonrecrossing hypothesis are small. Thus, the use of transition state theory, even with simplified reaction coordinates, provides a good theoretical framework for the study of enzymatic catalysis. Copyright © 2017 the Author(s). Published by PNAS.

Women, transition and strikes in Serbia

OpenAIRE

Novaković, Nada G.

2014-01-01

The author, in a sociological way, describes and analyzes the concepts of transition, privatization and strikes in Serbia, particularly the place of women in it. It examines the most important economic and social causes and consequences of these phenomena. The main hypothesis is: women's strikes in the Serbian transition are less efficient than strikes and public protests of women in the developed world and the second Yugoslavia. A strike is a class conflict, in which the workers are fighting...

The role of influenza in the epidemiology of pneumonia

Science.gov (United States)

Shrestha, Sourya; Foxman, Betsy; Berus, Joshua; van Panhuis, Willem G.; Steiner, Claudia; Viboud, Cécile; Rohani, Pejman

2015-01-01

Interactions arising from sequential viral and bacterial infections play important roles in the epidemiological outcome of many respiratory pathogens. Influenza virus has been implicated in the pathogenesis of several respiratory bacterial pathogens commonly associated with pneumonia. Though clinical evidence supporting this interaction is unambiguous, its population-level effects—magnitude, epidemiological impact and variation during pandemic and seasonal outbreaks—remain unclear. To address these unknowns, we used longitudinal influenza and pneumonia incidence data, at different spatial resolutions and across different epidemiological periods, to infer the nature, timing and the intensity of influenza-pneumonia interaction. We used a mechanistic transmission model within a likelihood-based inference framework to carry out formal hypothesis testing. Irrespective of the source of data examined, we found that influenza infection increases the risk of pneumonia by ~100-fold. We found no support for enhanced transmission or severity impact of the interaction. For model-validation, we challenged our fitted model to make out-of-sample pneumonia predictions during pandemic and non-pandemic periods. The consistency in our inference tests carried out on several distinct datasets, and the predictive skill of our model increase confidence in our overall conclusion that influenza infection substantially enhances the risk of pneumonia, though only for a short period. PMID:26486591

THE FRACTAL MARKET HYPOTHESIS

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FELICIA RAMONA BIRAU

2012-05-01

Full Text Available In this article, the concept of capital market is analysed using Fractal Market Hypothesis which is a modern, complex and unconventional alternative to classical finance methods. Fractal Market Hypothesis is in sharp opposition to Efficient Market Hypothesis and it explores the application of chaos theory and fractal geometry to finance. Fractal Market Hypothesis is based on certain assumption. Thus, it is emphasized that investors did not react immediately to the information they receive and of course, the manner in which they interpret that information may be different. Also, Fractal Market Hypothesis refers to the way that liquidity and investment horizons influence the behaviour of financial investors.

THE FRACTAL MARKET HYPOTHESIS

OpenAIRE

FELICIA RAMONA BIRAU

2012-01-01

In this article, the concept of capital market is analysed using Fractal Market Hypothesis which is a modern, complex and unconventional alternative to classical finance methods. Fractal Market Hypothesis is in sharp opposition to Efficient Market Hypothesis and it explores the application of chaos theory and fractal geometry to finance. Fractal Market Hypothesis is based on certain assumption. Thus, it is emphasized that investors did not react immediately to the information they receive and...

Learning-Related Changes in Adolescents' Neural Networks during Hypothesis-Generating and Hypothesis-Understanding Training

Science.gov (United States)

Lee, Jun-Ki; Kwon, Yongju

2012-01-01

Fourteen science high school students participated in this study, which investigated neural-network plasticity associated with hypothesis-generating and hypothesis-understanding in learning. The students were divided into two groups and participated in either hypothesis-generating or hypothesis-understanding type learning programs, which were…

A novel hypothesis splitting method implementation for multi-hypothesis filters

DEFF Research Database (Denmark)

Bayramoglu, Enis; Ravn, Ole; Andersen, Nils Axel

2013-01-01

The paper presents a multi-hypothesis filter library featuring a novel method for splitting Gaussians into ones with smaller variances. The library is written in C++ for high performance and the source code is open and free1. The multi-hypothesis filters commonly approximate the distribution tran...

Epidemiological correlates of breast cancer in South India.

Science.gov (United States)

Babu, Giridhara Rathnaiah; Lakshmi, Srikanthi Bodapati; Thiyagarajan, Jotheeswaran Amuthavalli

2013-01-01

Breast cancer is the most frequent cancer in women globally and represents the second leading cause of cancer death among women (after lung cancer). India is going through epidemiologic transition. It is reported that the incidence of breast cancer is rising rapidly as a result of changes in reproductive risk factors, dietary habits and increasing life expectancy, acting in concert with genetic factors. In order to understand the existing epidemiological correlates of breast cancer in South India, a systematic review of evidence available on epidemiologic correlates of breast cancer addressing incidence, prevalence, and associated factors like age, reproductive factors, cultural and religious factors was performed with specific focus on screening procedures in southern India. An increase in breast cancer incidence due to various modifiable risk factors was noted, especially in women over 40 years of age, with late stage of presentation, lack of awareness about screening, costs, fear and stigma associated with the disease serving as major barriers for early presentation. Educational strategies should be aimed at modifying the life style, early planning of pregnancy, promoting breast feeding and physical activity. It is very important to obtain reliable data for planning policies, decision-making and setting up the priorities.

Variability: A Pernicious Hypothesis.

Science.gov (United States)

Noddings, Nel

1992-01-01

The hypothesis of greater male variability in test results is discussed in its historical context, and reasons feminists have objected to the hypothesis are considered. The hypothesis acquires political importance if it is considered that variability results from biological, rather than cultural, differences. (SLD)

Mozambique field epidemiology and laboratory training program: a pathway for strengthening human resources in applied epidemiology.

Science.gov (United States)

Baltazar, Cynthia Semá; Taibo, Cátia; Sacarlal, Jahit; Gujral, Lorna; Salomão, Cristolde; Doyle, Timothy

2017-01-01

In the last decades, Mozambique has been undergoing demographic, epidemiological, economic and social transitions, which have all had a notable impact on the National Health System. New challenges have emerged, causing a need to expand the preparation and response to emerging disease threats and public health emergencies. We describe the structure and function of the Mozambique Field Epidemiology Training Program (MZ-FELTP) and the main outputs achieved during the first 6 years of program implementation (consisting of 3 cohorts). We also outline the contribution of the program to the National Health System and assess the retention of the graduates. The MZ-FELTP is a post-graduate in-service training program, based on the acquisition of skills, within two tracks: applied epidemiology and laboratory management. The program was established in 2010, with the objective of strengthening capacity in applied epidemiology and laboratory management, so that events of public health importance can be detected and investigated in a timely and effective manner. The program is in its seventh year, having successfully trained 36 health professionals in the advanced course. During the first six years of the program, more than 40 outbreaks were investigated, 37 surveillance system evaluations were conducted and 39 descriptive data analyses were performed. Surveillance activities were implemented for mass events and emergency situations. In addition, more than 100 oral and poster presentations were given by trainees at national and international conferences. The MZ-FELTP has helped provide the Ministry of Health with the human and technical resources and operational capacity, to rapidly and effectively respond to major public health challenges in the country. The continuous involvement of key stakeholders is necessary for the continuation, expansion and ongoing sustainability of the program.

Physiopathological Hypothesis of Cellulite

Science.gov (United States)

de Godoy, José Maria Pereira; de Godoy, Maria de Fátima Guerreiro

2009-01-01

A series of questions are asked concerning this condition including as regards to its name, the consensus about the histopathological findings, physiological hypothesis and treatment of the disease. We established a hypothesis for cellulite and confirmed that the clinical response is compatible with this hypothesis. Hence this novel approach brings a modern physiological concept with physiopathologic basis and clinical proof of the hypothesis. We emphasize that the choice of patient, correct diagnosis of cellulite and the technique employed are fundamental to success. PMID:19756187

Which transition comes first? Urban and demographic transitions in Belgium and Sweden

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Philippe Bocquier

2015-12-01

Full Text Available Background: Several theories compete to explain the main drivers of urbanisation, past and present, in relation to both demographic transition and economic development. One hypothesis is that rural-to-urban migration is the driver of urbanisation; another is that urban mortality decline actually triggered urban transition. Objective: This paper reconsiders the relationship between demographic (vital migration and urban transitions by analysing the long-term contribution of natural and migratory movements to urban transition. The respective contributions of birth, death, and migration and their timing will indicate whether economic development, through labour force migration, or vital transition mainly determines urban transition. Methods: After examining the spatial dimension of the demographic transition theory, we use 19th and 20th century series on Sweden and Belgium to better identify the migration component of urban transition through the computation of growth difference between urban and rural areas, accounting for the often neglected reclassification effect. Results: In both Sweden and Belgium, migration is the direct or indirect (through reclassification engine of urban transition and its contribution precedes the onset of vital transition, while the vital transition has a secondary, unstable, and negative role in the urban transition. Conclusions: Changes in the economic sphere are reinstated as the underlying cause of population change, acting through the shift of human capital in space. Methodological consequences are then drawn for analysing vital and urban transitions in an increasingly interdependent world. Contribution: The paper contributes to the theoretical literature on urban and demographic transitions in relation to economic development. The proposed method evaluates migration contribution without having to measure it.

Epidemiology of Suicide Attempts among Youth Transitioning to Adulthood.

Science.gov (United States)

Thompson, Martie P; Swartout, Kevin

2018-04-01

Suicide is the second leading cause of death for older adolescents and young adults. Although empirical literature has identified important risk factors of suicidal behavior, it is less understood if changes in risk factors correspond with changes in suicide risk. To address this knowledge gap, we assessed if there were different trajectories of suicidal behavior as youth transition into young adulthood and determined what time-varying risk factors predicted these trajectories. This study used four waves of data spanning approximately 13 years from the National Longitudinal Study of Adolescent Health. The sample included 9027 respondents who were 12-18 years old (M = 15.26; SD = 1.76) at Wave 1, 50% male, 17% Hispanic, and 58% White. The results indicated that 93.6% of the sample had a low likelihood for suicide attempts across time, 5.1% had an elevated likelihood of attempting suicide in adolescence but not young adulthood, and 1.3% had an elevated likelihood of attempting suicide during adolescence and adulthood. The likelihood of a suicide attempt corresponded with changes on depression, impulsivity, delinquency, alcohol problems, family and friend suicide history, and experience with partner violence. Determining how suicide risk changes as youth transition into young adulthood and what factors predict these changes can help prevent suicide. Interventions targeting these risk factors could lead to reductions in suicide attempts.

Participatory epidemiology: the contribution of participatory research to epidemiology

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Mario Bach

2017-02-01

Full Text Available Abstract Background Epidemiology has contributed in many ways to identifying various risk factors for disease and to promoting population health. However, there is a continuing debate about the ability of epidemiology not only to describe, but also to provide results which can be better translated into public health practice. It has been proposed that participatory research approaches be applied to epidemiology as a way to bridge this gap between description and action. A systematic account of what constitutes participatory epidemiology practice has, however, been lacking. Methods A scoping review was carried out focused on the question of what constitutes participatory approaches to epidemiology for the purpose of demonstrating their potential for advancing epidemiologic research. Relevant databases were searched, including both the published and non-published (grey literature. The 102 identified sources were analyzed in terms of comparing common epidemiologic approaches to participatory counterparts regarding central aspects of the research process. Exemplary studies applying participatory approaches were examined more closely. Results A highly diverse, interdisciplinary body of literature was synthesized, resulting in a framework comprised of seven aspects of the research process: research goal, research question, population, context, data synthesis, research management, and dissemination of findings. The framework specifies how participatory approaches not only differ from, but also how they can enhance common approaches in epidemiology. Finally, recommendations for the further development of participatory approaches are given. These include: enhancing data collection, data analysis, and data validation; advancing capacity building for research at the local level; and developing data synthesis. Conclusion The proposed framework provides a basis for systematically developing the emergent science of participatory epidemiology.

Fluorescence quenching and the "ring-mode" to "red-mode" transition in alkali inductively coupled plasmas

Science.gov (United States)

Huang, M.; Bazurto, R.; Camparo, J.

2018-01-01

The ring-mode to red-mode transition in alkali metal inductively coupled plasmas (ICPs) (i.e., rf-discharge lamps) is perhaps the most important physical phenomenon affecting these devices as optical pumping light sources for atomic clocks and magnetometers. It sets the limit on useful ICP operating temperature, thereby setting a limit on ICP light output for atomic-clock/magnetometer signal generation, and it is a temperature region of ICP operation associated with discharge instability. Previous work has suggested that the mechanism driving the ring-mode to red-mode transition is associated with radiation trapping, but definitive experimental evidence validating that hypothesis has been lacking. Based on that hypothesis, one would predict that the introduction of an alkali-fluorescence quenching gas (i.e., N2) into the ICP would increase the ring-mode to red-mode transition temperature. Here, we test that prediction, finding direct evidence supporting the radiation-trapping hypothesis.

Health transition in Brazil: regional variations and divergence/convergence in mortality.

Science.gov (United States)

Borges, Gabriel Mendes

2017-08-21

This study analyzes the main characteristics of the health transition in Brazil and its five major regions, using a framework that accounts for regional inequalities in mortality trends. The regional mortality divergence/convergence process is described and discussed by considering the specific contributions of age groups and causes of death in life expectancy variations. Results show that mortality change in Brazil has follow the epidemiologic transition theory to some extent during the period under analysis - for instance, the sharp decline in infant mortality in all regions (first from infectious and parasitic diseases and then from causes associated with the perinatal period) and the increase in the participation of chronic and degenerative diseases as the main cause of death. However, some features of Brazilian transition have not followed the linear and unidirectional pattern proposed by the epidemiologic transition theory, which helps to understand the periods of regional divergence in life expectancy, despite the long-term trends showing reducing regional inequalities. The emergence of HIV/AIDS, the persistence of relatively high levels of other infections and parasitic diseases, the regional differences in the unexpected mortality improvements from cardiovascular diseases, and the rapid and strong variations in mortality from external causes are some of the examples.

Critical phase transitions during ablation of atrial fibrillation

Science.gov (United States)

Iravanian, Shahriar; Langberg, Jonathan J.

2017-09-01

Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia with significant morbidity and mortality. Pharmacological agents are not very effective in the management of AF. Therefore, ablation procedures have become the mainstay of AF management. The irregular and seemingly chaotic atrial activity in AF is caused by one or more meandering spiral waves. Previously, we have shown the presence of sudden rhythm organization during ablation of persistent AF. We hypothesize that the observed transitions from a disorganized to an organized rhythm is a critical phase transition. Here, we explore this hypothesis by simulating ablation in an anatomically-correct 3D AF model. In 722 out of 2160 simulated ablation, at least one sudden transition from AF to an organized rhythm (flutter) was noted (33%). They were marked by a sudden decrease in the cycle length entropy and increase in the mean cycle length. At the same time, the number of reentrant wavelets decreased from 2.99 ± 0.06 in AF to 1.76 ± 0.05 during flutter, and the correlation length scale increased from 13.3 ± 1.0 mm to 196.5 ± 86.6 mm (both P < 0.0001). These findings are consistent with the hypothesis that transitions from AF to an anatomical flutter behave as phase transitions in complex non-equilibrium dynamical systems with flutter acting as an absorbing state. Clinically, the facilitation of phase transition should be considered a novel mechanism of ablation and may help to design effective ablation strategies.

The Income Inequality Hypothesis Revisited : Assessing the Hypothesis Using Four Methodological Approaches

NARCIS (Netherlands)

Kragten, N.; Rözer, J.

The income inequality hypothesis states that income inequality has a negative effect on individual’s health, partially because it reduces social trust. This article aims to critically assess the income inequality hypothesis by comparing several analytical strategies, namely OLS regression,

Testing Environmental Kuznets Curve in the Selected Transition Economies with Panel Smooth Transition Regression Analysis

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Mahmut Zortuk

2016-08-01

Full Text Available The Environmental Kuznets Curve (EKC introduces an inverted U-shaped relationship between environmental pollution and economic development. The inverted U-shaped curve is seen as complete pattern for developed economies. However, our study tests the EKC for developing transition economies of European Union, therefore, our results could make a significant contribution to the literature. In this paper, the relationship between carbon dioxide (CO2 emissions, gross domestic product (GDP, energy use and urban population is investigated in the Transition Economies (Bulgaria, Croatia, Czech Republic, Estonia, Hungary, Latvia, Lithuania, Poland, Romania, Slovakia and Slovenia. Environmental Kuznets Curve is tested by panel smooth transition regression for these economies for 1993 – 2010 periods. As a result of study, the null hypothesis of linearity was rejected and no-remaining nonlinearity test showed that there is a smooth transition exists between two regimes (below $5176 GDP per capita is first one and above $5176 GDP per capita is second one in the related period for these economies.

Radiation epidemiology: concept, methodology and statistical resources

International Nuclear Information System (INIS)

Vasques, Monica H. Braga; Carneiro, Janete C. Gaburo; Sordi, Gian M.A.

2008-01-01

As radiation exposure is the main point of interest in radiation epidemiology, epidemiologists try to relate the risk of diseases (mainly the risk of cancer) to the different levels and patterns of humankind exposure to radiation. Statistics as a branch of mathematics is able to prove associations and infer causality. As many researches are object of methodological limits, mainly those related to both the insufficient size of the sample and descriptive analysis as well as the choice of methods and variables, this paper aims at describing firstly the main kinds of epidemiological studies. Secondly, it relates distributions and summary measures (central tendency measures, measures of dispersion and normal distributions) and hypothesis tests as well necessary for each study. It also discusses the most appropriate statistical resource to the epidemiological evaluation. Finally, the main aim of this study is both to elaborate a systematic review of the researches that have been already done in Brazil since 2000, focusing on the effects caused by the occupational exposures to ionizing radiation in order to establish positive associations between them and to analyze the risk related to the workers health. This paper has as its basis the Reports in Public Health (Public Health Books-CSP) from which several studies about the exposure effects to ionizing radiation and referred kinds of cancer (e.g.: leukemia, skin cancer, thyroid gland cancer and bone cancer) have been taken as object of analysis. The relevance of this study lies in the most applied methods of risk to establish positive associations in ionizing radiation, in the relation between workers' workplace and his health. (author)

Global transition i sundhed

DEFF Research Database (Denmark)

Bygbjerg, Ib Christian; Meyrowitsch, Dan W

2006-01-01

, and by degenerative, and man-made diseases in ageing populations. Omran could not foresee the HIV/AIDS pandemic or the dramatic fall in longevity and fertility in, for example, Russia. But his model remains of value for health planners and politicians. We advocate for research in the interplay between diseases......Global epidemiological transition reflected in changed patterns of death and diseases was first described by Omran; decreasing death and disease rates from infectious diseases, particularly in children and the young, are followed by decreased fertility rate and increased longevity...

Invited Commentary: Can Issues With Reproducibility in Science Be Blamed on Hypothesis Testing?

Science.gov (United States)

Weinberg, Clarice R.

2017-01-01

Abstract In the accompanying article (Am J Epidemiol. 2017;186(6):646–647), Dr. Timothy Lash makes a forceful case that the problems with reproducibility in science stem from our “culture” of null hypothesis significance testing. He notes that when attention is selectively given to statistically significant findings, the estimated effects will be systematically biased away from the null. Here I revisit the recent history of genetic epidemiology and argue for retaining statistical testing as an important part of the tool kit. Particularly when many factors are considered in an agnostic way, in what Lash calls “innovative” research, investigators need a selection strategy to identify which findings are most likely to be genuine, and hence worthy of further study. PMID:28938713

A hypothesis to explain childhood cancers near nuclear power plants

International Nuclear Information System (INIS)

Fairlie, Ian

2014-01-01

Over 60 epidemiological studies world-wide have examined cancer incidences in children near nuclear power plants (NPPs): most of them indicate leukemia increases. These include the 2008 KiKK study commissioned by the German Government which found relative risks (RR) of 1.6 in total cancers and 2.2 in leukemias among infants living within 5 km of all German NPPs. The KiKK study has retriggered the debate as to the cause(s) of these increased cancers. A suggested hypothesis is that the increased cancers arise from radiation exposures to pregnant women near NPPs. However any theory has to account for the >10,000 fold discrepancy between official dose estimates from NPP emissions and observed increased risks. An explanation may be that doses from spikes in NPP radionuclide emissions are significantly larger than those estimated by official models which are diluted through the use of annual averages. In addition, risks to embryos/fetuses are greater than those to adults and haematopoietic tissues appear more radiosensitive in embryos/fetuses than in newborn babies. The product of possible increased doses and possible increased risks per dose may provide an explanation. - Highlights: • Over 60 studies worldwide on increased cancers near nuclear power plants (NPPs). • German government KiKK study provides very strong evidence. • Hypothesis proposes cancers arise in pregnant women near NPPs. • Nuclide spikes during refuelling could result in increased exposures. • Explanation offered for discrepancy between small dose estimates and large risks

On the Keyhole Hypothesis

DEFF Research Database (Denmark)

Mikkelsen, Kaare B.; Kidmose, Preben; Hansen, Lars Kai

2017-01-01

simultaneously recorded scalp EEG. A cross-validation procedure was employed to ensure unbiased estimates. We present several pieces of evidence in support of the keyhole hypothesis: There is a high mutual information between data acquired at scalp electrodes and through the ear-EEG "keyhole," furthermore we......We propose and test the keyhole hypothesis that measurements from low dimensional EEG, such as ear-EEG reflect a broadly distributed set of neural processes. We formulate the keyhole hypothesis in information theoretical terms. The experimental investigation is based on legacy data consisting of 10...

Government revenue-expenditure nexus: Evidence from several transitional economies

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Konukcu-Önal Debi

2008-01-01

Full Text Available Budget deficits and the debate on the sources of deficit finance have been on the agenda of public economics ever since the 1980s. However recently in the post-communist countries fiscal imbalances appear to be an important problem due to prolonged periods of growing poverty resulting from the transition process. Poverty alleviation policies considerably affect the revenue and expenditure decisions of governments, which are subject to hard budget constraints in an open transitional economy and do not have room for departing from sound fiscal policies. The public finance literature provides a vast number of studies analyzing the relationship between public revenues and expenditures. These studies are mostly characterized by efforts to reveal the attitude of the fiscal authority towards maintaining the budget balance. In this respect, budgetary dynamics in which past government revenues have predictive power on the current level of government expenditures are accepted as evidence of the so-called tax-and-spend hypothesis. On the other hand, the revenue-expenditure nexus running from expenditures to revenues is known in the literature as the spend-and-tax hypothesis. The objective of this study is to analyze empirically the relationship between government revenues and expenditures in four of the transitional economies, i.e. Belarus, Kazakhstan, the Kyrgyz Republic and the Russian Federation. The empirical findings of this study, which are based on Granger causality tests, indicate evidence supporting the tax-and-spend hypothesis in Belarus and the Russian Federation and fiscal synchronization in Kazakhstan and the Kyrgyz Republic. The empirical support for the tax-and-spend hypothesis in these economies implies that increasing government revenues may not end up with lower budget deficits due to their stimulating effect on the demand for public goods and services.

Approaches to informed consent for hypothesis-testing and hypothesis-generating clinical genomics research.

Science.gov (United States)

Facio, Flavia M; Sapp, Julie C; Linn, Amy; Biesecker, Leslie G

2012-10-10

Massively-parallel sequencing (MPS) technologies create challenges for informed consent of research participants given the enormous scale of the data and the wide range of potential results. We propose that the consent process in these studies be based on whether they use MPS to test a hypothesis or to generate hypotheses. To demonstrate the differences in these approaches to informed consent, we describe the consent processes for two MPS studies. The purpose of our hypothesis-testing study is to elucidate the etiology of rare phenotypes using MPS. The purpose of our hypothesis-generating study is to test the feasibility of using MPS to generate clinical hypotheses, and to approach the return of results as an experimental manipulation. Issues to consider in both designs include: volume and nature of the potential results, primary versus secondary results, return of individual results, duty to warn, length of interaction, target population, and privacy and confidentiality. The categorization of MPS studies as hypothesis-testing versus hypothesis-generating can help to clarify the issue of so-called incidental or secondary results for the consent process, and aid the communication of the research goals to study participants.

Scaling theory and the classification of phase transitions

International Nuclear Information System (INIS)

Hilfer, R.

1992-01-01

In this paper, the recent classification theory for phase transitions and its relation with the foundations of statistical physics is reviewed. First it is outlined how Ehrenfests classification scheme can be generalized into a general thermodynamic classification theory for phase transitions. The classification theory implies scaling and multiscaling thereby eliminating the need to postulate the scaling hypothesis as a fourth law of thermodynamics. The new classification has also led to the discovery and distinction of nonequilibrium transitions within equilibrium statistical physics. Nonequilibrium phase transitions are distinguished from equilibrium transitions by orders less than unity and by the fact the equilibrium thermodynamics and statistical mechanics become inapplicable at the critical point. The latter fact requires a change in the Gibbs assumption underlying the canonical and grandcanonical ensembles in order to recover the thermodynamic description in the critical limit

Establishing the link between Ostreopsis cf.ovata blooms and human health impacts using ecology and epidemiology

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Magda Vila

2016-09-01

Full Text Available Blooms of the benthic dinoflagellate Ostreopsis have been related to sporadic acute respiratory symptoms and general malaise in people exposed to marine aerosols on some Mediterranean beaches. However, the direct link between recurrent Ostreopsis blooms and health problems has not been clearly established. In order to establish and elucidate the connection, we conducted a joint ecology and epidemiology study in an Ostreopsis hot spot. Throughout the bloom, which extended from the end of June until the end of October 2013, 81% of the human cohort that we studied experienced at least one Ostreopsis-related symptom. Paradoxically, the time when the effects were greatest was during a short time window in early August. This corresponded to the transition from the exponential growth to the stationary phase of the bloom. Negligible symptoms were reported from August to mid-October, during the stationary period of the proliferation, when O. cf. ovata maintained high concentrations of epiphytic cells. No clear patterns in the landward wind component were noted during the time when health effects were greatest. Our main hypothesis is that the irritants present in the aerosol are produced during a particular physiological phase of the Ostreopsis cells during the bloom.

[Epidemiological transition of mycosis diseases in sub-Saharan Africa: from surface to depth].

Science.gov (United States)

Chandenier, J; Desoubeaux, G

2015-02-01

Fungi are schematically responsible for three distinct kinds of infections: superficial mycoses, subcutaneous and deep ones. The current socio-epidemiological transition observed in sub-Saharan Africa does not actually lead to similar consequences regarding these three categories of fungal entities. For instance, it has long been known that superficial mycoses are very prevalent in tropical areas, since they are partly due to the warm climate and the promiscuity. They are mostly caused by dermatophytic fungi or Malassezia sp. (Pityriasis versicolor). Subcutaneous mycoses are rarer, and usually due to dimorphic fungi which are accidentally inoculated into the body after a skin injury or a trauma. Sometimes very spectacular, the clinical outcome is then described as chronic. Thus, chromoblastomycosis, rhinoentomophtoromycosis or mycetoma are some examples of subcutaneous mycoses which remain well-known by practitioners of endemic countries. Deep mycoses (or invasive / systemic mycoses) are defined by fungal infections of deep anatomical sites that should be normally sterile. By contrast with the other entities mentioned above, the outcome may be rapidly fatal for the patient. One of the most outstanding examples was the great increasing of cryptococcal meningitis during the HIV outbreak in the 80'. A few other similar mycoses may be feared in a near future, since they usually occur in contexts of important immunosuppression which are about to be definitely experienced in Africa: overall increase of chronic diseases like diabetes, lengthening life expectancy and its associated diseases, widespread medical practices which were only seen in advanced intensive care units, onco-haematology departments or graft centers so far. Thus, the deep mycoses will inevitably increase in Africa, as they did in all developed countries over the last two decades. The consequences will not only be limited to the clinical management as described above: the diagnostic approach is also

TESTS OF THE PLANETARY HYPOTHESIS FOR PTFO 8-8695b

International Nuclear Information System (INIS)

Yu, Liang; Winn, Joshua N.; Rappaport, Saul; Dai, Fei; Triaud, Amaury H. M. J.; Gillon, Michaël; Delrez, Laetitia; Jehin, Emmanuel; Lendl, Monika; Albrecht, Simon; Bieryla, Allyson; Holman, Matthew J.; Montet, Benjamin T.; Hillenbrand, Lynne; Howard, Andrew W.; Huang, Chelsea X.; Isaacson, Howard; Sanchis-Ojeda, Roberto; Muirhead, Philip

2015-01-01

The T Tauri star PTFO 8-8695 exhibits periodic fading events that have been interpreted as the transits of a giant planet on a precessing orbit. Here we present three tests of the planet hypothesis. First, we sought evidence for the secular changes in light-curve morphology that are predicted to be a consequence of orbital precession. We observed 28 fading events spread over several years and did not see the expected changes. Instead, we found that the fading events are not strictly periodic. Second, we attempted to detect the planet's radiation, based on infrared observations spanning the predicted times of occultations. We ruled out a signal of the expected amplitude. Third, we attempted to detect the Rossiter–McLaughlin effect by performing high-resolution spectroscopy throughout a fading event. No effect was seen at the expected level, ruling out most (but not all) possible orientations for the hypothetical planetary orbit. Our spectroscopy also revealed strong, time-variable, high-velocity Hα and Ca H and K emission features. All these observations cast doubt on the planetary hypothesis, and suggest instead that the fading events represent starspots, eclipses by circumstellar dust, or occultations of an accretion hotspot

The transition to modernity and chronic disease: mismatch and natural selection.

Science.gov (United States)

Corbett, Stephen; Courtiol, Alexandre; Lummaa, Virpi; Moorad, Jacob; Stearns, Stephen

2018-05-09

The Industrial Revolution and the accompanying nutritional, epidemiological and demographic transitions have profoundly changed human ecology and biology, leading to major shifts in life history traits, which include age and size at maturity, age-specific fertility and lifespan. Mismatch between past adaptations and the current environment means that gene variants linked to higher fitness in the past may now, through antagonistic pleiotropic effects, predispose post-transition populations to non-communicable diseases, such as Alzheimer disease, cancer and coronary artery disease. Increasing evidence suggests that the transition to modernity has also altered the direction and intensity of natural selection acting on many traits, with important implications for public and global health.

Hypothesis in research

Directory of Open Access Journals (Sweden)

Eudaldo Enrique Espinoza Freire

2018-01-01

Full Text Available It is intended with this work to have a material with the fundamental contents, which enable the university professor to formulate the hypothesis, for the development of an investigation, taking into account the problem to be solved. For its elaboration, the search of information in primary documents was carried out, such as thesis of degree and reports of research results, selected on the basis of its relevance with the analyzed subject, current and reliability, secondary documents, as scientific articles published in journals of recognized prestige, the selection was made with the same terms as in the previous documents. It presents a conceptualization of the updated hypothesis, its characterization and an analysis of the structure of the hypothesis in which the determination of the variables is deepened. The involvement of the university professor in the teaching-research process currently faces some difficulties, which are manifested, among other aspects, in an unstable balance between teaching and research, which leads to a separation between them.

Using Two Different Approaches to Assess Dietary Patterns: Hypothesis-Driven and Data-Driven Analysis

Directory of Open Access Journals (Sweden)

Ágatha Nogueira Previdelli

2016-09-01

Full Text Available The use of dietary patterns to assess dietary intake has become increasingly common in nutritional epidemiology studies due to the complexity and multidimensionality of the diet. Currently, two main approaches have been widely used to assess dietary patterns: data-driven and hypothesis-driven analysis. Since the methods explore different angles of dietary intake, using both approaches simultaneously might yield complementary and useful information; thus, we aimed to use both approaches to gain knowledge of adolescents’ dietary patterns. Food intake from a cross-sectional survey with 295 adolescents was assessed by 24 h dietary recall (24HR. In hypothesis-driven analysis, based on the American National Cancer Institute method, the usual intake of Brazilian Healthy Eating Index Revised components were estimated. In the data-driven approach, the usual intake of foods/food groups was estimated by the Multiple Source Method. In the results, hypothesis-driven analysis showed low scores for Whole grains, Total vegetables, Total fruit and Whole fruits, while, in data-driven analysis, fruits and whole grains were not presented in any pattern. High intakes of sodium, fats and sugars were observed in hypothesis-driven analysis with low total scores for Sodium, Saturated fat and SoFAA (calories from solid fat, alcohol and added sugar components in agreement, while the data-driven approach showed the intake of several foods/food groups rich in these nutrients, such as butter/margarine, cookies, chocolate powder, whole milk, cheese, processed meat/cold cuts and candies. In this study, using both approaches at the same time provided consistent and complementary information with regard to assessing the overall dietary habits that will be important in order to drive public health programs, and improve their efficiency to monitor and evaluate the dietary patterns of populations.

Factors involved in the paradox of reverse epidemiology.

Science.gov (United States)

Martín-Ponce, Esther; Santolaria, Francisco; Alemán-Valls, María-Remedios; González-Reimers, Emilio; Martínez-Riera, Antonio; Rodríguez-Gaspar, Melchor; Rodríguez-Rodríguez, Eva

2010-08-01

The hypothesis of reverse epidemiology holds that some cardiovascular risk factors, such as obesity, hypercholesterolemia and hypertension, in the elderly or in some chronic diseases are not harmful but permit better survival. However, this phenomenon is controversial and the underlying reasons are poorly understood. To search for factors simultaneously linked to reverse epidemiology and to short or long term survival. We included 400 patients, older than 60 years, hospitalized in a general internal medicine unit; 61 died in hospital and 338 were followed up by telephone. Obesity, higher blood pressure and serum cholesterol, besides being related to lower mortality both in hospital and after discharge, were associated with better nutrition and functional capacity, less intense acute phase reaction and organ dysfunction, and lower incidence of high-mortality diseases such as dementia, pneumonia, sepsis or cancer. These associations may explain why obesity and other reverse epidemiology data are inversely related to mortality. Weight loss was related to mortality independently of BMI. Patients with BMI under 30 kg/m(2) who died in hospital showed more weight loss than those who survived; the lower the BMI, the greater the weight loss. In contrast, patients with BMI over 30 kg/m(2) who died in hospital gained more weight than those who survived; the higher the BMI, the greater the weight gain. In patients over 60 years of age admitted to an internal medicine ward, obesity did not show independent survival value, being displaced by other nutritional parameters, functional capacity, acute phase reaction, organ dysfunction and diseases with poor prognosis. Copyright 2009 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.

Is the Aluminum Hypothesis Dead?

Science.gov (United States)

2014-01-01

The Aluminum Hypothesis, the idea that aluminum exposure is involved in the etiology of Alzheimer disease, dates back to a 1965 demonstration that aluminum causes neurofibrillary tangles in the brains of rabbits. Initially the focus of intensive research, the Aluminum Hypothesis has gradually been abandoned by most researchers. Yet, despite this current indifference, the Aluminum Hypothesis continues to attract the attention of a small group of scientists and aluminum continues to be viewed with concern by some of the public. This review article discusses reasons that mainstream science has largely abandoned the Aluminum Hypothesis and explores a possible reason for some in the general public continuing to view aluminum with mistrust. PMID:24806729

Men’s Perception of Raped Women: Test of the Sexually Transmitted Disease Hypothesis and the Cuckoldry Hypothesis

Directory of Open Access Journals (Sweden)

Prokop Pavol

2016-06-01

Full Text Available Rape is a recurrent adaptive problem of female humans and females of a number of non-human animals. Rape has various physiological and reproductive costs to the victim. The costs of rape are furthermore exaggerated by social rejection and blaming of a victim, particularly by men. The negative perception of raped women by men has received little attention from an evolutionary perspective. Across two independent studies, we investigated whether the risk of sexually transmitted diseases (the STD hypothesis, Hypothesis 1 or paternity uncertainty (the cuckoldry hypothesis, Hypothesis 2 influence the negative perception of raped women by men. Raped women received lower attractiveness score than non-raped women, especially in long-term mate attractiveness score. The perceived attractiveness of raped women was not influenced by the presence of experimentally manipulated STD cues on faces of putative rapists. Women raped by three men received lower attractiveness score than women raped by one man. These results provide stronger support for the cuckoldry hypothesis (Hypothesis 2 than for the STD hypothesis (Hypothesis 1. Single men perceived raped women as more attractive than men in a committed relationship (Hypothesis 3, suggesting that the mating opportunities mediate men’s perception of victims of rape. Overall, our results suggest that the risk of cuckoldry underlie the negative perception of victims of rape by men rather than the fear of disease transmission.

Epidemiology and costs of diabetes.

Science.gov (United States)

Bruno, G; Landi, A

2011-01-01

The prevalence of diabetes is increasing worldwide, particularly in developing countries. In the next decades, India and China are expected to provide the greatest numbers of affected people, mainly owing to the increasing incidence of this disease in those countries. Regarding developed countries, such as in Europe and the United States, the increasing trend is mainly due to the prolonged survival of both the general and the diabetic populations. From an epidemiologic point of view, the first relevant point is that almost 80% of diabetes cases could be prevented just by avoiding overweight and obesity. The estimated attributable risk of excess body weight is extremely high; no other modifiable effect has such an impact on the health of the general population. The second relevant point is that the global trend of the disease shows a tendency to onset at a younger age. The third point is that in developed countries the prevalence of diabetes is increasing mainly among the elderly, who are responsible for the highest consumption of health care resources in absolute terms. Regarding type 1 diabetes, which represents one-tenth of affected individuals, both large geographic and temporal variations in disease incidence have been found, supporting the hypothesis of as yet unknown environmental determinants. The incidence is increasing in linear fashion, not supporting the hypothesis of younger age at onset as the main explanation for this trend. Because the prevalences of both type 1 and type 2 diabetes are increasing worldwide, they will produce a profound impact on overall health care costs. Copyright © 2011 Elsevier Inc. All rights reserved.

Evaluation of epidemiological studies

International Nuclear Information System (INIS)

Breckow, J.

1995-01-01

The publication is intended for readers with a professional background in radiation protection who are not experts in the field of epidemiology. The potentials and the limits of epidemiology are shown and concepts and terminology of radioepidemilogic studies as well as epidemiology in general are explained, in order to provide the necessary basis for understanding or performing evaluations of epidemiologic studies. (orig./VHE) [de

Corporate governance cycles during transition

DEFF Research Database (Denmark)

Mygind, Niels; Demina, Natalia; Gregoric, Aleksandra

2004-01-01

-ing or exit stage. During transition the cycle reflects: privatization often with a high proportion of employee ownership like in Russia and in Slovenia; strong pressures for restructuring and owner-ship changes; limited possibility for external finance because of embryonic development of the fi......-nancial system. To provide simple hypothesis tests, we use Russian enterprise data for 1995-2003 and Slovenian data covering 1998-2003. In spite of differences in institutional development, con-cerning privatization and development of corporate governance institutions, we find that govern-ance cycles are broadly...... of ownership on managers, external domestic and foreign owners. JEL-codes: G3, J5, P2, P3 - Keywords: corporate governance, life-cycle, privatization, ownership change, transition economies, Russia and Slovenia....

Early hominins in Europe: The Galerian migration hypothesis

Science.gov (United States)

Muttoni, Giovanni; Scardia, Giancarlo; Kent, Dennis V.

2018-01-01

Our updated review of sites bearing hominin remains and/or tools from Europe, including new findings from the Balkans, still indicates that the only compelling evidence of main hominin presence in these regions was only since ∼0.9 million years ago (Ma), bracketed by the end of the Jaramillo geomagnetic polarity subchron (0.99 Ma) and the Brunhes-Matuyama polarity chron boundary (0.78 Ma). This time window straddled the late Early Pleistocene climate transition (EPT) at the onset of enhanced glacial/interglacial activity that reverberated worldwide. Europe may have become initially populated during the EPT when, possibly for the first time in the Pleistocene, vast and exploitable ecosystems were generated along the eustatically emergent Po-Danube terrestrial conduit. These newly formed settings, characterized by stable terrestrial lowlands with open grasslands and reduced woody cover especially during glacial/interglacial transitions, are regarded as optimal ecosystems for several large Galerian immigrant mammals such as African and Asian megaherbivores, possibly linked with hominins in a common food web, to expand into en route to Europe. The question of when hominins first arrived in Europe thus places the issue in the context of changes in climate, paleogeography and faunal associations as potential environmental drivers and controlling agents in a specific time frame, a key feature of the Galerian migration hypothesis.

Food insecurity as a driver of obesity in humans: The insurance hypothesis

Science.gov (United States)

Nettle, Daniel; Andrews, Clare; Bateson, Melissa

2016-01-01

Short abstract Common sense says that obesity is the consequence of too much food. Adaptive reasoning says something rather different: individuals should store fat when access to food is insecure, to buffer themselves against future shortfall. Applied to humans, this principle suggests that food insecurity should be a risk factor for overweight and obesity. We provide a meta-analysis of the extensive epidemiological literature, finding that food insecurity robustly predicts high body weight, but only amongst women in high-income countries. We discuss the relevance of food insecurity to understanding the global obesity problem. Long abstract Integrative explanations of why obesity is more prevalent in some sectors of the human population than others are lacking. Here, we outline and evaluate one candidate explanation, the insurance hypothesis (IH). The IH is rooted in adaptive evolutionary thinking: the function of storing fat is to provide a buffer against shortfall in the food supply. Thus, individuals should store more fat when they receive cues that access to food is uncertain. Applied to humans, this implies that an important proximate driver of obesity should be food insecurity rather than food abundance per se. We integrate several distinct lines of theory and evidence that bear on this hypothesis. We present a theoretical model that shows it is optimal to store more fat when food access is uncertain, and we review the experimental literature from non-human animals showing that fat reserves increase when access to food is restricted. We provide a meta-analysis of 125 epidemiological studies of the association between perceived food insecurity and high body weight in humans. There is a robust positive association, but it is restricted to adult women in high-income countries. We explore why this could be in light of the IH and our theoretical model. We conclude that whilst the IH alone cannot explain the distribution of obesity in the human population, it may

Low dose epidemiology

International Nuclear Information System (INIS)

Tirmarche, M.; Hubert, P.

1992-01-01

Actually, epidemiological studies have to establish if the assessment of cancer risk can be verified at low chronic radiation doses. The population surveillance must be very long, the side effects and cancers of such radiation appearing much later. In France, this epidemiological study on nuclear workers have been decided recently. Before describing the experiment and french projects in epidemiology of nuclear workers, the authors present the main english and american studies

Mobile DNA and the TE-Thrust hypothesis: supporting evidence from the primates

Directory of Open Access Journals (Sweden)

Oliver Keith R

2011-05-01

Full Text Available Abstract Transposable elements (TEs are increasingly being recognized as powerful facilitators of evolution. We propose the TE-Thrust hypothesis to encompass TE-facilitated processes by which genomes self-engineer coding, regulatory, karyotypic or other genetic changes. Although TEs are occasionally harmful to some individuals, genomic dynamism caused by TEs can be very beneficial to lineages. This can result in differential survival and differential fecundity of lineages. Lineages with an abundant and suitable repertoire of TEs have enhanced evolutionary potential and, if all else is equal, tend to be fecund, resulting in species-rich adaptive radiations, and/or they tend to undergo major evolutionary transitions. Many other mechanisms of genomic change are also important in evolution, and whether the evolutionary potential of TE-Thrust is realized is heavily dependent on environmental and ecological factors. The large contribution of TEs to evolutionary innovation is particularly well documented in the primate lineage. In this paper, we review numerous cases of beneficial TE-caused modifications to the genomes of higher primates, which strongly support our TE-Thrust hypothesis.

Life shocks and crime: a test of the "turning point" hypothesis.

Science.gov (United States)

Corman, Hope; Noonan, Kelly; Reichman, Nancy E; Schwartz-Soicher, Ofira

2011-08-01

Other researchers have posited that important events in men's lives-such as employment, marriage, and parenthood-strengthen their social ties and lead them to refrain from crime. A challenge in empirically testing this hypothesis has been the issue of self-selection into life transitions. This study contributes to this literature by estimating the effects of an exogenous life shock on crime. We use data from the Fragile Families and Child Wellbeing Study, augmented with information from hospital medical records, to estimate the effects of the birth of a child with a severe health problem on the likelihood that the infant's father engages in illegal activities. We conduct a number of auxiliary analyses to examine exogeneity assumptions. We find that having an infant born with a severe health condition increases the likelihood that the father is convicted of a crime in the three-year period following the birth of the child, and at least part of the effect appears to operate through work and changes in parental relationships. These results provide evidence that life events can cause crime and, as such, support the "turning point" hypothesis.

Should the history of epidemiology be taught in epidemiology training programs?

Science.gov (United States)

Laskaris, Zoey; Morabia, Alfredo

2015-01-01

Currently, there is no evidence concerning the presence of historical content in the epidemiology curricula of the United States and abroad. Similarly, it is not known how epidemiologists view this topic in the context of master's or doctoral level course work. We attempted to fill these knowledge gaps with data from 2 online surveys-Survey I administered to persons in charge of all epidemiology training programs in North America and Survey II to epidemiologists practicing around the world. A substantial minority (39%) of graduate programs in epidemiology in the United States teach a course on the history of the field. In both surveys, the most common reasons selected for teaching such a course were "To build a sense of identity as an epidemiologist" and "As a tool for achieving a deeper understanding into specific methods and concepts." The majority of respondents, from 63 countries, agreed that the history of epidemiology should be included in curricula for graduate students in epidemiology.

Epidemiologic characteristics and risk factors for renal cell cancer

Directory of Open Access Journals (Sweden)

Loren Lipworth

2009-04-01

Full Text Available Loren Lipworth1,2, Robert E Tarone1,2, Lars Lund2,3, Joseph K McLaughlin1,21International Epidemiology Institute, Rockville, MD, USA; 2Department of Medicine (JKM, RET and Preventive Medicine (LL, Vanderbilt University Medical Center and Vanderbilt-Ingram Cancer Center, Nashville, TN, USA; 3Department of Urology, Viborg Hospital, Viborg, DenmarkAbstract: Incidence rates of renal cell cancer, which accounts for 85% of kidney cancers, have been rising in the United States and in most European countries for several decades. Family history is associated with a two- to four-fold increase in risk, but the major forms of inherited predisposition together account for less than 4% of renal cell cancers. Cigarette smoking, obesity, and hypertension are the most consistently established risk factors. Analgesics have not been convincingly linked with renal cell cancer risk. A reduced risk of renal cell cancer among statin users has been hypothesized but has not been adequately studied. A possible protective effect of fruit and vegetable consumption is the only moderately consistently reported dietary finding, and, with the exception of a positive association with parity, evidence for a role of hormonal or reproductive factors in the etiology of renal cell cancer in humans is limited. A recent hypothesis that moderate levels of alcohol consumption may be protective for renal cell cancer is not strongly supported by epidemiologic results, which are inconsistent with respect to the categories of alcohol consumption and the amount of alcohol intake reportedly associated with decreased risk. For occupational factors, the weight of the evidence does not provide consistent support for the hypotheses that renal cell cancer may be caused by asbestos, gasoline, or trichloroethylene exposure. The established determinants of renal cell cancer, cigarette smoking, obesity, and hypertension, account for less than half of these cancers. Novel epidemiologic approaches

[Multiple sclerosis epidemiological situation update: pertinence and set-up of a population based registry of new cases in Catalonia].

Science.gov (United States)

Otero, S; Batlle, J; Bonaventura, I; Brieva, Ll; Bufill, E; Cano, A; Carmona, O; Escartín, A; Marco, M; Moral, E; Munteis, E; Nos, C; Pericot, I; Perkal, H; Ramió-Torrentà, Ll; Ramo-Tello, C; Saiz, A; Sastre-Garriga, J; Tintoré, M; Vaqué, J; Montalban, X

2010-05-16

The first epidemiological studies on multiple sclerosis (MS) around the world pictured a north to south latitudinal gradient that led to the first genetic and environmental pathogenic hypothesis. MS incidence seems to be increasing during the past 20 years based on recent data from prospective studies performed in Europe, America and Asia. This phenomenon could be explained by a better case ascertainment as well as a change in causal factors. The few prospective studies in our area together with the increase in the disease in other regions, justifies an epidemiological MS project in order to describe the incidence and temporal trends of MS. A prospective multicenter MS registry has been established according to the actual requirements of an epidemiological surveillance system. Case definition is based on the fulfillment of the McDonald diagnostic criteria. The registry setting is the geographical area of Cataluna (northeastern Spain), using a wide network of hospitals specialized in MS management. Recent epidemiological studies have described an increase in MS incidence. In order to contrast this finding in our area, we consider appropriate to set up a population based registry.

Shared dosimetry error in epidemiological dose-response analyses

International Nuclear Information System (INIS)

Stram, Daniel O.; Preston, Dale L.; Sokolnikov, Mikhail; Napier, Bruce; Kopecky, Kenneth J.; Boice, John; Beck, Harold; Till, John; Bouville, Andre; Zeeb, Hajo

2015-01-01

Radiation dose reconstruction systems for large-scale epidemiological studies are sophisticated both in providing estimates of dose and in representing dosimetry uncertainty. For example, a computer program was used by the Hanford Thyroid Disease Study to provide 100 realizations of possible dose to study participants. The variation in realizations reflected the range of possible dose for each cohort member consistent with the data on dose determinates in the cohort. Another example is the Mayak Worker Dosimetry System 2013 which estimates both external and internal exposures and provides multiple realizations of 'possible' dose history to workers given dose determinants. This paper takes up the problem of dealing with complex dosimetry systems that provide multiple realizations of dose in an epidemiologic analysis. In this paper we derive expected scores and the information matrix for a model used widely in radiation epidemiology, namely the linear excess relative risk (ERR) model that allows for a linear dose response (risk in relation to radiation) and distinguishes between modifiers of background rates and of the excess risk due to exposure. We show that treating the mean dose for each individual (calculated by averaging over the realizations) as if it was true dose (ignoring both shared and unshared dosimetry errors) gives asymptotically unbiased estimates (i.e. the score has expectation zero) and valid tests of the null hypothesis that the ERR slope β is zero. Although the score is unbiased the information matrix (and hence the standard errors of the estimate of β) is biased for β≠0 when ignoring errors in dose estimates, and we show how to adjust the information matrix to remove this bias, using the multiple realizations of dose. The use of these methods in the context of several studies including, the Mayak Worker Cohort, and the U.S. Atomic Veterans Study, is discussed

Reassessing the Trade-off Hypothesis

DEFF Research Database (Denmark)

Rosas, Guillermo; Manzetti, Luigi

2015-01-01

Do economic conditions drive voters to punish politicians that tolerate corruption? Previous scholarly work contends that citizens in young democracies support corrupt governments that are capable of promoting good economic outcomes, the so-called trade-off hypothesis. We test this hypothesis based...

Epidemiology of malaria in the forest-savanna transitional zone of Ghana

Directory of Open Access Journals (Sweden)

Newton Sam

2009-09-01

Full Text Available Abstract Background Information on the epidemiology of malaria is essential for designing and interpreting results of clinical trials of drugs, vaccines and other interventions. As a background to the establishment of a site for anti-malarial drugs and vaccine trials, the epidemiology of malaria in a rural site in central Ghana was investigated. Methods Active surveillance of clinical malaria was carried out in a cohort of children below five years of age (n = 335 and the prevalence of malaria was estimated in a cohort of subjects of all ages (n = 1484 over a 12-month period. Participants were sampled from clusters drawn around sixteen index houses randomly selected from a total of about 22,000 houses within the study area. The child cohort was visited thrice weekly to screen for any illness and a blood slide was taken if a child had a history of fever or a temperature greater than or equal to 37.5 degree Celsius. The all-age cohort was screened for malaria once every eight weeks over a 12-month period. Estimation of Entomological Inoculation Rate (EIR and characterization of Anopheline malaria vectors in the study area were also carried out. Results The average parasite prevalence in the all age cohort was 58% (95% CI: 56.9, 59.4. In children below five years of age, the average prevalence was 64% (95% CI: 61.9, 66.0. Geometric mean parasite densities decreased significantly with increasing age. More than 50% of all children less than 10 years of age were anaemic. Children less than 5 years of age had as many as seven malaria attacks per child per year. The attack rates decreased significantly with increasing cut-offs of parasite density. The average Multiplicity of Infection (MOI was of 6.1. All three pyrimethamine resistance mutant alleles of the Plasmodium falciparum dhfr gene were prevalent in this population and 25% of infections had a fourth mutant of pfdhps-A437G. The main vectors were Anopheles funestus and Anopheles gambiae and the EIR

Water deficit severity during berry development alters timing of dormancy transitions in wine grape cultivar Malbec

Science.gov (United States)

The objective of this study was to test the hypothesis that vine water stress during the growing season can lengthen the dormancy cycle by inducing earlier transition into endodormancy. A bud forcing assay was used to compare the dormancy transitions of field-grown ‘Malbec’ grapevines that had been ...

Tests of the lunar hypothesis

Science.gov (United States)

Taylor, S. R.

1984-01-01

The concept that the Moon was fissioned from the Earth after core separation is the most readily testable hypothesis of lunar origin, since direct comparisons of lunar and terrestrial compositions can be made. Differences found in such comparisons introduce so many ad hoc adjustments to the fission hypothesis that it becomes untestable. Further constraints may be obtained from attempting to date the volatile-refractory element fractionation. The combination of chemical and isotopic problems suggests that the fission hypothesis is no longer viable, and separate terrestrial and lunar accretion from a population of fractionated precursor planetesimals provides a more reasonable explanation.

Epidemiology of IBD

Science.gov (United States)

... IBD? Projects and Partners Data and Statistics Resources Epidemiology of the IBD Recommend on Facebook Tweet Share ... 5:1424-9. 2 Loftus EV, Jr. Clinical epidemiology of inflammatory bowel disease: Incidence, prevalence, and environmental ...

The New Epidemiology--A Challenge to Health Administration. Issues in Epidemiology for Administration.

Science.gov (United States)

Crichton, Anne, Ed.; Neuhauser, Duncan, Ed.

The role of epidemiology in health administration is considered in 11 articles, and three course descriptions and a bibliography are provided. Titles and authors include the following: "The Need for Creative Managerial Epidemiology" (Gary L. Filerman); "The Growing Role of Epidemiology in Health Administration" (Maureen M.…

Temperature-dependent phase transitions in zeptoliter volumes of a complex biological membrane

International Nuclear Information System (INIS)

Nikiforov, Maxim P; Jesse, Stephen; Kalinin, Sergei V; Hohlbauch, Sophia; Proksch, Roger; King, William P; Voitchovsky, Kislon; Contera, Sonia Antoranz

2011-01-01

Phase transitions in purple membrane have been a topic of debate for the past two decades. In this work we present studies of a reversible transition of purple membrane in the 50-60 deg. C range in zeptoliter volumes under different heating regimes (global heating and local heating). The temperature of the reversible phase transition is 52 ± 5 deg. C for both local and global heating, supporting the hypothesis that this transition is mainly due to a structural rearrangement of bR molecules and trimers. To achieve high resolution measurements of temperature-dependent phase transitions, a new scanning probe microscopy-based method was developed. We believe that our new technique can be extended to other biological systems and can contribute to the understanding of inhomogeneous phase transitions in complex systems.

Notes on the Epidemiology of Multiple Sclerosis, with Special Reference to Dietary Habits

Science.gov (United States)

Lauer, Klaus

2014-01-01

A hypothesis, based primarily on the occurrence of multiple sclerosis (MS) in the Faroe Islands and supported by numerous analytical epidemiological studies, is described. It proposes that MS is caused by the interaction of a virus disease with intestinal pathology, e.g., infectious mononucleosis, and application of smoked and nitrate/nitrite-cured meat products in the diet during circumscribed time intervals. The biological mechanisms might involve a break of tolerance by an alteration of self within the central nervous system, by nitrophenylated compounds conjugated to animal tissue, in particular to proteins occurring in the central nervous system. Further research is needed. PMID:24577315

Low-energy effective models for two-flavor quantum chromodynamics and the universality hypothesis

International Nuclear Information System (INIS)

Grahl, Mara

2014-01-01

Our thesis is centered around the question of which order the chiral phase transition of two-flavor QCD is. First of all we outline several general aspects of phase transitions which are of central importance for the understanding of the RG approach towards them. Our focus lies on reviewing the universality hypothesis, a crucial ingredient when it comes to the construction of effective theories for order parameters, the credibility of which often heavily depends on universality arguments. We finish the chapter with an attempt to formulate the latter more precisely than usually done. The next chapter discusses the chiral phase transition from a general point of view. We supplement well-known facts with a detailed discussion of the so-called O(4) conjecture. Thereafter we introduce the nonperturbative method we use, the FRG method. Furthermore, we discuss the relation between effective models for QCD and the underlying fundamental theory making use of the FRG perspective. The next chapter is concerned with a mathematical subject indispensable for our approach towards the study of phase transitions, namely the systematic construction of polynomial invariants characterizing a given symmetry. With this thesis we point out its relevance in the context of high-energy physics. We present a simple, but novel, brute-force algorithm to effectively construct invariants of a given polynomial order. The next chapter is devoted to RG studies of several dimensionally reduced theories which are capable to either predict or to rule out the possible existence of a second-order phase transition. Of main interest for us is the linear sigma model, particularly in presence of the axial anomaly. It turns out that the fixed-point structure of the latter is rather complicated, requiring a deeper understanding of the underlying method and its preconditions. This leads us to a careful analysis of the fixed-point structure of several models, which is of great benefit for our review of the

Soluble transition metals cause the pro-inflammatory effects of welding fumes in vitro

International Nuclear Information System (INIS)

McNeilly, Jane D.; Heal, Mathew R.; Beverland, Iain J.; Howe, Alan; Gibson, Mark D.; Hibbs, Leon R.; MacNee, William; Donaldson, Ken

2004-01-01

Epidemiological studies have consistently reported a higher incidence of respiratory illnesses such as bronchitis, metal fume fever (MFF), and chronic pneumonitis among welders exposed to high concentrations of metal-enriched welding fumes. Here, we studied the molecular toxicology of three different metal-rich welding fumes: NIMROD 182, NIMROD c276, and COBSTEL 6. Fume toxicity in vitro was determined by exposing human type II alveolar epithelial cell line (A549) to whole welding fume, a soluble extract of fume or the 'washed' particulate. All whole fumes were significantly toxic to A549 cells at doses >63 μg ml -1 (TD 50; 42, 25, and 12 μg ml -1 , respectively). NIMROD c276 and COBSTEL 6 fumes increased levels of IL-8 mRNA and protein at 6 h and protein at 24 h, as did the soluble fraction alone, whereas metal chelation of the soluble fraction using chelex beads attenuated the effect. The soluble fraction of all three fumes caused a rapid depletion in intracellular glutathione following 2-h exposure with a rebound increase by 24 h. In addition, both nickel based fumes, NIMROD 182 and NIMROD c276, induced significant reactive oxygen species (ROS) production in A549 cells after 2 h as determined by DCFH fluorescence. ICP analysis confirmed that transition metal concentrations were similar in the whole and soluble fractions of each fume (dominated by Cr), but significantly less in both the washed particles and chelated fractions. These results support the hypothesis that the enhanced pro-inflammatory responses of welding fume particulates are mediated by soluble transition metal components via an oxidative stress mechanism

Functions, Operations, and Decalage in the Development of Transitivity.

Science.gov (United States)

Chapman, Michael; Lindenberger, Ulman

1988-01-01

Tested the hypothesis that some attempts to reduce the performance demands of concrete Piagetian operational tasks may have allowed children to solve those tasks with preoperational functions. Administered two previously used versions of the transitivity task for length and weight to 120 children six- to nine-years-old. The second version was…

Mental models accurately predict emotion transitions.

Science.gov (United States)

Thornton, Mark A; Tamir, Diana I

2017-06-06

Successful social interactions depend on people's ability to predict others' future actions and emotions. People possess many mechanisms for perceiving others' current emotional states, but how might they use this information to predict others' future states? We hypothesized that people might capitalize on an overlooked aspect of affective experience: current emotions predict future emotions. By attending to regularities in emotion transitions, perceivers might develop accurate mental models of others' emotional dynamics. People could then use these mental models of emotion transitions to predict others' future emotions from currently observable emotions. To test this hypothesis, studies 1-3 used data from three extant experience-sampling datasets to establish the actual rates of emotional transitions. We then collected three parallel datasets in which participants rated the transition likelihoods between the same set of emotions. Participants' ratings of emotion transitions predicted others' experienced transitional likelihoods with high accuracy. Study 4 demonstrated that four conceptual dimensions of mental state representation-valence, social impact, rationality, and human mind-inform participants' mental models. Study 5 used 2 million emotion reports on the Experience Project to replicate both of these findings: again people reported accurate models of emotion transitions, and these models were informed by the same four conceptual dimensions. Importantly, neither these conceptual dimensions nor holistic similarity could fully explain participants' accuracy, suggesting that their mental models contain accurate information about emotion dynamics above and beyond what might be predicted by static emotion knowledge alone.

Mental models accurately predict emotion transitions

Science.gov (United States)

Thornton, Mark A.; Tamir, Diana I.

2017-01-01

Successful social interactions depend on people’s ability to predict others’ future actions and emotions. People possess many mechanisms for perceiving others’ current emotional states, but how might they use this information to predict others’ future states? We hypothesized that people might capitalize on an overlooked aspect of affective experience: current emotions predict future emotions. By attending to regularities in emotion transitions, perceivers might develop accurate mental models of others’ emotional dynamics. People could then use these mental models of emotion transitions to predict others’ future emotions from currently observable emotions. To test this hypothesis, studies 1–3 used data from three extant experience-sampling datasets to establish the actual rates of emotional transitions. We then collected three parallel datasets in which participants rated the transition likelihoods between the same set of emotions. Participants’ ratings of emotion transitions predicted others’ experienced transitional likelihoods with high accuracy. Study 4 demonstrated that four conceptual dimensions of mental state representation—valence, social impact, rationality, and human mind—inform participants’ mental models. Study 5 used 2 million emotion reports on the Experience Project to replicate both of these findings: again people reported accurate models of emotion transitions, and these models were informed by the same four conceptual dimensions. Importantly, neither these conceptual dimensions nor holistic similarity could fully explain participants’ accuracy, suggesting that their mental models contain accurate information about emotion dynamics above and beyond what might be predicted by static emotion knowledge alone. PMID:28533373

Basic concepts of epidemiology

International Nuclear Information System (INIS)

Savitz, D.A.

1984-01-01

Epidemiology can be defined simply as the science of the distribution and determinants of disease in human populations. As a descriptive tool, epidemiology can aid health care service providers, for example, in allocation of resources. In its analytic capacity, the epidemiologic approach can help identify determinants of disease through the study of human populations. Epidemiology is primarily an observational rather than experimental methodology, with corresponding strengths and limitations. Relative to other approaches for assessing disease etiology and impacts of potential health hazards, epidemiology has a rather unique role that is complementary to, but independent of, both basic biologic sciences and clinical medicine. Experimental biologic sciences such as toxicology and physiology provide critical information on biologic mechanisms of disease required for causal inference. Clinical medicine often serves as the warning system that provides etiologic clues to be pursued through systematic investigation. The advantage of the epidemiologic approach is its reliance on human field experience, that is, the real world. While laboratory experimentation is uniquely well suited to defining potential hazards, it can neither determine whether human populations have actually been affected nor quantify that effect. Building all the complexities of human behavior and external factors into a laboratory study or mathematical model is impossible. By studying the world as it exists, epidemiology examines the integrated, summarized product of the myriad factors influencing health

WHO - IPHECA: Epidemiological aspects

International Nuclear Information System (INIS)

Souchkevitch, G.

1996-01-01

In May 1991 the World Health Assembly endorsed the establishment of the International Programme on the Health Effects of the Chernobyl Accident (IPHECA) under the auspices of WHO. Five pilot projects have been carried out within IPHECA in the study territories of Belarus, Russian Federation and Ukraine in a period from 1991 to 1994. This pilot projects dealt with the detection and treatment of leukaemia and related diseases (Haematology Project), thyroid disorders (Thyroid project), brain damage during exposure 'in-utero' (Brain Damage 'in-Utero' project) and with the development of the Chernobyl registries (Epidemiological Registry Project). A fifth pilot project on oral health was performed only in Belarus. Epidemiological investigations have been an important component of all IPHECA pilot projects. Within 'Epidemiological Registry' Project such investigations have been the principal activity. But with respect to other IPHECA projects it was carried out in addition to main objectives relating to medical monitoring, early diagnosis and treatment of specific diseases included in project protocols. To support the epidemiological investigations within IPHECA, WHO supplied 41 computers in Belarus, Russian Federation and Ukraine and provided training for specialists from these countries in internationally recognized centres. The training programmes and host countries were as follows: standardization of epidemiological investigations (United Kingdom), radiation epidemiology (Russia), development of software (United Kingdom), principles of epidemiological investigations (The Czech Republic), cohort investigations (Japan)

WHO - IPHECA: Epidemiological aspects

Energy Technology Data Exchange (ETDEWEB)

Souchkevitch, G [World Health Organization, Geneva (Swaziland)

1996-07-01

In May 1991 the World Health Assembly endorsed the establishment of the International Programme on the Health Effects of the Chernobyl Accident (IPHECA) under the auspices of WHO. Five pilot projects have been carried out within IPHECA in the study territories of Belarus, Russian Federation and Ukraine in a period from 1991 to 1994. This pilot projects dealt with the detection and treatment of leukaemia and related diseases (Haematology Project), thyroid disorders (Thyroid project), brain damage during exposure 'in-utero' (Brain Damage 'in-Utero' project) and with the development of the Chernobyl registries (Epidemiological Registry Project). A fifth pilot project on oral health was performed only in Belarus. Epidemiological investigations have been an important component of all IPHECA pilot projects. Within 'Epidemiological Registry' Project such investigations have been the principal activity. But with respect to other IPHECA projects it was carried out in addition to main objectives relating to medical monitoring, early diagnosis and treatment of specific diseases included in project protocols. To support the epidemiological investigations within IPHECA, WHO supplied 41 computers in Belarus, Russian Federation and Ukraine and provided training for specialists from these countries in internationally recognized centres. The training programmes and host countries were as follows: standardization of epidemiological investigations (United Kingdom), radiation epidemiology (Russia), development of software (United Kingdom), principles of epidemiological investigations (The Czech Republic), cohort investigations (Japan)

Q-values of mirror transitions for fundamental interaction studies

CERN Multimedia

The $Ft$ values for the $0^{+} \\rightarrow 0^{+}$ superallowed $\\beta$-transitions currently provide the best test of the CVC hypothesis, and the most precise determination of the V$_{ud}$ element of the CKM matrix. Recent experimental advances, including direct mass measurements with Penning traps, have led to the precision in the corrected $Ft$ values being dominated by the theoretical corrections rather than experiment. An alternative route are the isospin $T$=1/2 mirror transitions where experimental uncertainties dominate over the theoretical inputs and which can provide an independent test of CVC, and ultimately an independent evaluation of V$_{ud}$. We propose mass measurements of 4 different mirror transitions aiming for a precision of better than 100eV on the ${Q}$-values.

The Qualitative Expectations Hypothesis

DEFF Research Database (Denmark)

Frydman, Roman; Johansen, Søren; Rahbek, Anders

We introduce the Qualitative Expectations Hypothesis (QEH) as a new approach to modeling macroeconomic and financial outcomes. Building on John Muth's seminal insight underpinning the Rational Expectations Hypothesis (REH), QEH represents the market's forecasts to be consistent with the predictions...... of an economist's model. However, by assuming that outcomes lie within stochastic intervals, QEH, unlike REH, recognizes the ambiguity faced by an economist and market participants alike. Moreover, QEH leaves the model open to ambiguity by not specifying a mechanism determining specific values that outcomes take...

Direct detection and quantification of transition metal ions in human atherosclerotic plaques

DEFF Research Database (Denmark)

Stadler, Nadina; Lindner, Robyn A; Davies, Michael Jonathan

2004-01-01

OBJECTIVE: The involvement of transition metals in atherosclerosis is controversial. Some epidemiological studies have reported a relationship between iron (Fe) and cardiovascular disease, whereas others have not. Experimental studies have reported elevated levels of iron and copper (Cu) in disea......OBJECTIVE: The involvement of transition metals in atherosclerosis is controversial. Some epidemiological studies have reported a relationship between iron (Fe) and cardiovascular disease, whereas others have not. Experimental studies have reported elevated levels of iron and copper (Cu......) in diseased human arteries but have often used methods that release metal ions from proteins. METHODS AND RESULTS: In this study, we have used the minimally invasive technique of electron paramagnetic resonance (EPR) spectroscopy and inductively coupled plasma mass spectroscopy (ICPMS) to quantify iron...... and copper in ex vivo healthy human arteries and carotid lesions. The EPR spectra detected are characteristic of nonheme Fe(III) complexes. Statistically elevated levels of iron were detected in the intima of lesions compared with healthy controls (0.370 versus 0.022 nmol/mg tissue for EPR, 0.525 versus 0...

Methodologic frontiers in environmental epidemiology.

OpenAIRE

Rothman, K J

1993-01-01

Environmental epidemiology comprises the epidemiologic study of those environmental factors that are outside the immediate control of the individual. Exposures of interest to environmental epidemiologists include air pollution, water pollution, occupational exposure to physical and chemical agents, as well as psychosocial elements of environmental concern. The main methodologic problem in environmental epidemiology is exposure assessment, a problem that extends through all of epidemiologic re...

An adaptive workspace hypothesis about the neural correlates of consciousness: insights from neuroscience and meditation studies.

Science.gov (United States)

Raffone, Antonino; Srinivasan, Narayanan

2009-01-01

While enormous progress has been made to identify neural correlates of consciousness (NCC), crucial NCC aspects are still very controversial. A major hurdle is the lack of an adequate definition and characterization of different aspects of conscious experience and also its relationship to attention and metacognitive processes like monitoring. In this paper, we therefore attempt to develop a unitary theoretical framework for NCC, with an interdependent characterization of endogenous attention, access consciousness, phenomenal awareness, metacognitive consciousness, and a non-referential form of unified consciousness. We advance an adaptive workspace hypothesis about the NCC based on the global workspace model emphasizing transient resonant neurodynamics and prefrontal cortex function, as well as meditation-related characterizations of conscious experiences. In this hypothesis, transient dynamic links within an adaptive coding net in prefrontal cortex, especially in anterior prefrontal cortex, and between it and the rest of the brain, in terms of ongoing intrinsic and long-range signal exchanges, flexibly regulate the interplay between endogenous attention, access consciousness, phenomenal awareness, and metacognitive consciousness processes. Such processes are established in terms of complementary aspects of an ongoing transition between context-sensitive global workspace assemblies, modulated moment-to-moment by body and environment states. Brain regions associated to momentary interoceptive and exteroceptive self-awareness, or first-person experiential perspective as emphasized in open monitoring meditation, play an important modulatory role in adaptive workspace transitions.

Life Shocks and Crime: A Test of the “Turning Point” Hypothesis

Science.gov (United States)

Noonan, Kelly; Reichman, Nancy E.; Schwartz-Soicher, Ofira

2012-01-01

Other researchers have posited that important events in men’s lives—such as employment, marriage, and parenthood—strengthen their social ties and lead them to refrain from crime. A challenge in empirically testing this hypothesis has been the issue of self-selection into life transitions. This study contributes to this literature by estimating the effects of an exogenous life shock on crime. We use data from the Fragile Families and Child Wellbeing Study, augmented with information from hospital medical records, to estimate the effects of the birth of a child with a severe health problem on the likelihood that the infant’s father engages in illegal activities. We conduct a number of auxiliary analyses to examine exogeneity assumptions. We find that having an infant born with a severe health condition increases the likelihood that the father is convicted of a crime in the three-year period following the birth of the child, and at least part of the effect appears to operate through work and changes in parental relationships. These results provide evidence that life events can cause crime and, as such, support the “turning point” hypothesis. PMID:21660628

A Service Member's Self in Transition : A Longitudinal Case Study Analysis

NARCIS (Netherlands)

Grimell, Jan

2017-01-01

Adopting a narrative approach with a dialogical framework, a longitudinal case study is presented that describes a service member's self in transition from active service into the civilian population. An analysis and interpretation of the case study leads to the hypothesis that if a dominant

Perspective: Structural fluctuation of protein and Anfinsen's thermodynamic hypothesis

Science.gov (United States)

Hirata, Fumio; Sugita, Masatake; Yoshida, Masasuke; Akasaka, Kazuyuki

2018-01-01

The thermodynamics hypothesis, casually referred to as "Anfinsen's dogma," is described theoretically in terms of a concept of the structural fluctuation of protein or the first moment (average structure) and the second moment (variance and covariance) of the structural distribution. The new theoretical concept views the unfolding and refolding processes of protein as a shift of the structural distribution induced by a thermodynamic perturbation, with the variance-covariance matrix varying. Based on the theoretical concept, a method to characterize the mechanism of folding (or unfolding) is proposed. The transition state, if any, between two stable states is interpreted as a gap in the distribution, which is created due to an extensive reorganization of hydrogen bonds among back-bone atoms of protein and with water molecules in the course of conformational change. Further perspective to applying the theory to the computer-aided drug design, and to the material science, is briefly discussed.

Epidemiological causality.

Science.gov (United States)

Morabia, Alfredo

2005-01-01

Epidemiological methods, which combine population thinking and group comparisons, can primarily identify causes of disease in populations. There is therefore a tension between our intuitive notion of a cause, which we want to be deterministic and invariant at the individual level, and the epidemiological notion of causes, which are invariant only at the population level. Epidemiologists have given heretofore a pragmatic solution to this tension. Causal inference in epidemiology consists in checking the logical coherence of a causality statement and determining whether what has been found grossly contradicts what we think we already know: how strong is the association? Is there a dose-response relationship? Does the cause precede the effect? Is the effect biologically plausible? Etc. This approach to causal inference can be traced back to the English philosophers David Hume and John Stuart Mill. On the other hand, the mode of establishing causality, devised by Jakob Henle and Robert Koch, which has been fruitful in bacteriology, requires that in every instance the effect invariably follows the cause (e.g., inoculation of Koch bacillus and tuberculosis). This is incompatible with epidemiological causality which has to deal with probabilistic effects (e.g., smoking and lung cancer), and is therefore invariant only for the population.

The Qualitative Expectations Hypothesis

DEFF Research Database (Denmark)

Frydman, Roman; Johansen, Søren; Rahbek, Anders

2017-01-01

We introduce the Qualitative Expectations Hypothesis (QEH) as a new approach to modeling macroeconomic and financial outcomes. Building on John Muth's seminal insight underpinning the Rational Expectations Hypothesis (REH), QEH represents the market's forecasts to be consistent with the predictions...... of an economistís model. However, by assuming that outcomes lie within stochastic intervals, QEH, unlike REH, recognizes the ambiguity faced by an economist and market participants alike. Moreover, QEH leaves the model open to ambiguity by not specifying a mechanism determining specific values that outcomes take...

Pesticide Exposure and Neurodevelopmental Outcomes: Review of the Epidemiologic and Animal Studies

Science.gov (United States)

Burns, Carol J.; McIntosh, Laura J.; Mink, Pamela J.; Jurek, Anne M.; Li, Abby A.

2013-01-01

Assessment of whether pesticide exposure is associated with neurodevelopmental outcomes in children can best be addressed with a systematic review of both the human and animal peer-reviewed literature. This review analyzed epidemiologic studies testing the hypothesis that exposure to pesticides during pregnancy and/or early childhood is associated with neurodevelopmental outcomes in children. Studies that directly queried pesticide exposure (e.g., via questionnaire or interview) or measured pesticide or metabolite levels in biological specimens from study participants (e.g., blood, urine, etc.) or their immediate environment (e.g., personal air monitoring, home dust samples, etc.) were eligible for inclusion. Consistency, strength of association, and dose response were key elements of the framework utilized for evaluating epidemiologic studies. As a whole, the epidemiologic studies did not strongly implicate any particular pesticide as being causally related to adverse neurodevelopmental outcomes in infants and children. A few associations were unique for a health outcome and specific pesticide, and alternative hypotheses could not be ruled out. Our survey of the in vivo peer-reviewed published mammalian literature focused on effects of the specific active ingredient of pesticides on functional neurodevelopmental endpoints (i.e., behavior, neuropharmacology and neuropathology). In most cases, effects were noted at dose levels within the same order of magnitude or higher compared to the point of departure used for chronic risk assessments in the United States. Thus, although the published animal studies may have characterized potential neurodevelopmental outcomes using endpoints not required by guideline studies, the effects were generally observed at or above effect levels measured in repeated-dose toxicology studies submitted to the U.S. Environmental Protection Agency (EPA). Suggestions for improved exposure assessment in epidemiology studies and more effective

The need for kidney transplantation in low- and middle-income countries in 2012: an epidemiological perspective.

Science.gov (United States)

Muralidharan, Aditya; White, Sarah

2015-03-01

Epidemiological and demographic transitions are shifting the burden of modifiable risk factors for chronic and end-stage kidney disease to low- and middle-income countries (LMIC). This shifting burden of disease--combined with economic transitions and health system reforms--has led to the rapid growth of dialysis populations in LMIC including Malaysia, Tunisia, Turkey, Chile, Mexico, and Uruguay. Yet, compared to 1.5 million on dialysis in LMIC, only approximately 33,000 kidney transplants were performed in 2012. Reasons include health system factors (personnel, infrastructure, system coordination, and financing) and cultural factors (public and professional attitudes and the legal environment). The size of the dialysis populations, however, is generally a poor indicator of the potential need for kidney transplantation in LMIC. Population needs for kidney transplantation should instead be assessed based on the epidemiology of the actual underlying burden of disease (both treated and untreated), and the costs and benefits of treatment as well as prevention strategies relative to existing service provision. Here, we review current data on the global burden of end-stage kidney disease and the distribution of major risk factors, and compare this to access to kidney transplantation in 2012.

Epidemiology: Then and Now.

Science.gov (United States)

Kuller, Lewis H

2016-03-01

Twenty-five years ago, on the 75th anniversary of the Johns Hopkins Bloomberg School of Public Health, I noted that epidemiologic research was moving away from the traditional approaches used to investigate "epidemics" and their close relationship with preventive medicine. Twenty-five years later, the role of epidemiology as an important contribution to human population research, preventive medicine, and public health is under substantial pressure because of the emphasis on "big data," phenomenology, and personalized medical therapies. Epidemiology is the study of epidemics. The primary role of epidemiology is to identify the epidemics and parameters of interest of host, agent, and environment and to generate and test hypotheses in search of causal pathways. Almost all diseases have a specific distribution in relation to time, place, and person and specific "causes" with high effect sizes. Epidemiology then uses such information to develop interventions and test (through clinical trials and natural experiments) their efficacy and effectiveness. Epidemiology is dependent on new technologies to evaluate improved measurements of host (genomics), epigenetics, identification of agents (metabolomics, proteomics), new technology to evaluate both physical and social environment, and modern methods of data collection. Epidemiology does poorly in studying anything other than epidemics and collections of numerators and denominators without specific hypotheses even with improved statistical methodologies. © The Author 2015. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Drug abuse: vulnerability and transition to addiction.

Science.gov (United States)

Le Moal, M

2009-05-01

Intrinsic vulnerability is central to the transition of recreational drug use to misuse. Several factors contribute to vulnerability, inherent or acquired, and they account for the huge individual differences observed concerning the propensity to enter in the addiction process. Some of the multifactional causes for a vulnerable phenotype will be examined: genetic factors, age and gender influences, various comorbidities and epidemiological observations. Stress-induced vulnerability will be particularly reviewed because it provides a good model for a pathophysiological research and for relating environmental events to biological consequences of drug vulnerability, namely through the striato-cortical dopamine system. Experimental studies are generally blind concerning these historical factors that contribute vulnerability and a critical evaluation of current animal models is needed. The transition of the last stage of the process, addiction, is conceptualized as a progression from homeostasis to allostasis and then, to pathology.

Epidemiology and the Tobacco Epidemic: How Research on Tobacco and Health Shaped Epidemiology.

Science.gov (United States)

Samet, Jonathan M

2016-03-01

In this article, I provide a perspective on the tobacco epidemic and epidemiology, describing the impact of the tobacco-caused disease epidemic on the field of epidemiology. Although there is an enormous body of epidemiologic evidence on the associations of smoking with health, little systematic attention has been given to how decades of research have affected epidemiology and its practice. I address the many advances that resulted from epidemiologic research on smoking and health, such as demonstration of the utility of observational designs and important parameters (the odds ratio and the population attributable risk), guidelines for causal inference, and systematic review approaches. I also cover unintended and adverse consequences for the field, including the strategy of doubt creation and the recruitment of epidemiologists by the tobacco industry to serve its mission. The paradigm of evidence-based action for addressing noncommunicable diseases began with the need to address the epidemic of tobacco-caused disease, an imperative for action documented by epidemiologic research. © The Author 2016. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Validity of Linder Hypothesis in Bric Countries

Directory of Open Access Journals (Sweden)

Rana Atabay

2016-03-01

Full Text Available In this study, the theory of similarity in preferences (Linder hypothesis has been introduced and trade in BRIC countries has been examined whether the trade between these countries was valid for this hypothesis. Using the data for the period 1996 – 2010, the study applies to panel data analysis in order to provide evidence regarding the empirical validity of the Linder hypothesis for BRIC countries’ international trade. Empirical findings show that the trade between BRIC countries is in support of Linder hypothesis.

Epidemiology applied to health physics

International Nuclear Information System (INIS)

1983-01-01

The technical program of the mid-year meeting of the Health Physics Society, entitled Epidemiology Applied to Health physics, was developed to meet three objectives: (1) give health physicists a deeper understanding of the basics of epidemiological methods and their use in developing standards, regulations, and criteria and in risk assessment; (2) present current reports on recently completed or on-going epidemiology studies; and (3) encourage greater interaction between the health physics and epidemiology disciplines. Included are studies relating methods in epidemiology to radiation protection standards, risk assessment from exposure to bone-seekers, from occupational exposures in mines, mills and nuclear facilities, and from radioactivity in building materials

Sentence production with verbs of alternating transitivity in agrammatic Broca's aphasia

NARCIS (Netherlands)

Bastiaanse, Y.R.M.; van Zonneveld, R.M.

Bastiaanse, Koekkoek And Van Zonneveld (2003) hypothesized that individuals with Broca's aphasia have problems with sentences in which the verb and its arguments are not in their base position. The present study is meant to test this hypothesis with the help of verbs with alternating transitivity:

Food insecurity as a driver of obesity in humans: The insurance hypothesis.

Science.gov (United States)

Nettle, Daniel; Andrews, Clare; Bateson, Melissa

2017-01-01

Integrative explanations of why obesity is more prevalent in some sectors of the human population than others are lacking. Here, we outline and evaluate one candidate explanation, the insurance hypothesis (IH). The IH is rooted in adaptive evolutionary thinking: The function of storing fat is to provide a buffer against shortfall in the food supply. Thus, individuals should store more fat when they receive cues that access to food is uncertain. Applied to humans, this implies that an important proximate driver of obesity should be food insecurity rather than food abundance per se. We integrate several distinct lines of theory and evidence that bear on this hypothesis. We present a theoretical model that shows it is optimal to store more fat when food access is uncertain, and we review the experimental literature from non-human animals showing that fat reserves increase when access to food is restricted. We provide a meta-analysis of 125 epidemiological studies of the association between perceived food insecurity and high body weight in humans. There is a robust positive association, but it is restricted to adult women in high-income countries. We explore why this could be in light of the IH and our theoretical model. We conclude that although the IH alone cannot explain the distribution of obesity in the human population, it may represent a very important component of a pluralistic explanation. We also discuss insights it may offer into the developmental origins of obesity, dieting-induced weight gain, and anorexia nervosa.

Einstein's Revolutionary Light-Quantum Hypothesis

Science.gov (United States)

Stuewer, Roger H.

2005-05-01

The paper in which Albert Einstein proposed his light-quantum hypothesis was the only one of his great papers of 1905 that he himself termed ``revolutionary.'' Contrary to widespread belief, Einstein did not propose his light-quantum hypothesis ``to explain the photoelectric effect.'' Instead, he based his argument for light quanta on the statistical interpretation of the second law of thermodynamics, with the photoelectric effect being only one of three phenomena that he offered as possible experimental support for it. I will discuss Einstein's light-quantum hypothesis of 1905 and his introduction of the wave-particle duality in 1909 and then turn to the reception of his work on light quanta by his contemporaries. We will examine the reasons that prominent physicists advanced to reject Einstein's light-quantum hypothesis in succeeding years. Those physicists included Robert A. Millikan, even though he provided convincing experimental proof of the validity of Einstein's equation of the photoelectric effect in 1915. The turning point came after Arthur Holly Compton discovered the Compton effect in late 1922, but even then Compton's discovery was contested both on experimental and on theoretical grounds. Niels Bohr, in particular, had never accepted the reality of light quanta and now, in 1924, proposed a theory, the Bohr-Kramers-Slater theory, which assumed that energy and momentum were conserved only statistically in microscopic interactions. Only after that theory was disproved experimentally in 1925 was Einstein's revolutionary light-quantum hypothesis generally accepted by physicists---a full two decades after Einstein had proposed it.

[Algorithm for application of the "ethical guidelines for epidemiological research" and taxonomy of public health research].

Science.gov (United States)

Okamoto, Etsuji

2003-11-01

"Ethical Guidelines for Epidemiological Research" took effect in July 2002, with a moral duty of all researchers to comply when conducting epidemiological studies although it is not legally binding. Public health research entails various forms of studies including not only epidemiological studies but also attention to psychological, societal and economic aspects, which are outside of the jurisdiction of the guidelines. Hence, confusion may arise among members of Japanese Society of Public Health as to whether the study they conduct falls within the definition of epidemiological research. The author discusses legal interpretations of the guidelines arising in the course of translation work as part of government-funded project, "Dissemination of the 'Ethical Guidelines for Epidemiological Research' via Internet (principal investigator: Toru Doi)" and argues that a case-method approach would be best suited to enhance understanding by researchers with diverse, non-legal backgrounds. The author proposes an algorithm for classification of studies as to whether the guideline applies, and applies it to all original articles published in the Japanese Journal of Public Health (JJPH) in one year (March 2002 thru February 2003). The rationale for classification is discussed from the strict legal viewpoint in each case. Sixteen out of 46 original articles published in JJPH for one year were classified as epidemiological studies to which the guidelines apply. Those classified otherwise were psychological studies (10), epidemiological studies not targeting specific diseases and are exempt form the guidelines (3), purely methodological studies (4), economics studies (3), fact-finding or opinion surveys with no hypothesis testing (2), as well as studies authorized by law (4) or using unlinkable anonymous data only (4), all of which are exempt from the guidelines. Reference to ethical considerations in the methodology section as required by the instructions for authors was generally

CEDR: Comprehensive Epidemiologic Data Resource

Energy Technology Data Exchange (ETDEWEB)

1993-08-01

The Department of Energy (DOE) and its predecessor agencies have a long history of epidemiologic research programs. The main focus of these programs has been the Health and Mortality Study of the DOE work force. This epidemiologic study began in 1964 with a feasibility study of workers at the Hanford facility. Studies of other populations exposed to radiation have also been supported, including the classic epidemiologic study of radium dial painters and studies of atomic bomb survivors. From a scientific perspective, these epidemiologic research program have been productive, highly credible, and formed the bases for many radiological protection standards. Recently, there has been concern that, although research results were available, the data on which these results were based were not easily obtained by interested investigators outside DOE. Therefore, as part of an effort to integrate and broaden access to its epidemiologic information, the DOE has developed the Comprehensive Epidemiologic Data Resource (CEDR) Program. Included in this effort is the development of a computer information system for accessing the collection of CEDR data and its related descriptive information. The epidemiologic data currently available through the CEDAR Program consist of analytic data sets, working data sets, and their associated documentation files. In general, data sets are the result of epidemiologic studies that have been conducted on various groups of workers at different DOE facilities during the past 30 years.

Mapping epidemiology's past to inform its future: metaknowledge analysis of epidemiologic topics in leading journals, 1974-2013.

Science.gov (United States)

Trinquart, Ludovic; Galea, Sandro

2015-07-15

An empiric perspective on what epidemiology has studied over time might inform discussions about future directions for the discipline. We aimed to identify the main areas of epidemiologic inquiry and determine how they evolved over time in 5 high-impact epidemiologic journals. We analyzed the titles and abstracts of 20,895 articles that were published between 1974 and 2013. In 5 time periods that reflected approximately equal numbers of articles, we identified the main topics by clustering terms based on co-occurrence. Infectious disease and cardiovascular disease epidemiology were the prevailing topics over the 5 periods. Cancer epidemiology was a major topic from 1974 to 2001 but disappeared thereafter. Nutritional epidemiology gained relative importance from 1974 to 2013. Environmental epidemiology appeared during 1996-2001 and continued to be important, whereas 2 clusters related to methodology and meta-analysis in genetics appeared during 2008-2013. Several areas of epidemiology, including injury or psychiatric epidemiology, did not make an appearance as major topics at any time. In an ancillary analysis of 6 high-impact general medicine journals, we found patterns of epidemiologic articles that were overall consistent with the findings in epidemiologic journals. This metaknowledge investigation allowed identification of the dominant topics in and conversely those that were absent from 5 major epidemiologic journals. We discuss implications for the field. © The Author 2015. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

A test of the comet hypothesis of the Tunguska Meteor Fall - Nature of the meteor 'thermal' explosion paradox

Science.gov (United States)

Liu, V. C.

1978-01-01

The hypothesis that a comet was responsible for the Tunguska Meteor Fall is rejected because the hypothesis does not seem to account for the intense terminal spherical shock. A porous meteoroid model is proposed, and an analysis indicates that an entity of this type might produce an aerodynamic heat flux large enough to account for the terminal meteor explosion. It is suggested that the presence of olivine and of highly irregular macrostructure in meteors might indicate the presence of some porosity. For a highly porous meteoroid, it is postulated that during entry into the atmosphere the aerodynamic heat transfer at its external or pore walls would become so intensified as to cause either complete ablation with popping or a solid-liquid-vapor phase transition accompanied by an explosion.

Invited Commentary: Can Issues With Reproducibility in Science Be Blamed on Hypothesis Testing?

Science.gov (United States)

Weinberg, Clarice R

2017-09-15

In the accompanying article (Am J Epidemiol. 2017;186(6):646-647), Dr. Timothy Lash makes a forceful case that the problems with reproducibility in science stem from our "culture" of null hypothesis significance testing. He notes that when attention is selectively given to statistically significant findings, the estimated effects will be systematically biased away from the null. Here I revisit the recent history of genetic epidemiology and argue for retaining statistical testing as an important part of the tool kit. Particularly when many factors are considered in an agnostic way, in what Lash calls "innovative" research, investigators need a selection strategy to identify which findings are most likely to be genuine, and hence worthy of further study. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health 2017. This work is written by (a) US Government employee(s) and is in the public domain in the US.

International Lymphoma Epidemiology Consortium

Science.gov (United States)

The InterLymph Consortium, or formally the International Consortium of Investigators Working on Non-Hodgkin's Lymphoma Epidemiologic Studies, is an open scientific forum for epidemiologic research in non-Hodgkin's lymphoma.

Anorexigen-induced pulmonary hypertension and the serotonin (5-HT hypothesis: lessons for the future in pathogenesis

Directory of Open Access Journals (Sweden)

Adnot Serge

2002-01-01

Full Text Available Abstract Epidemiological studies have established that fenfluramine, D-fenfluramine, and aminorex, but not other appetite suppressants, increase the risk of primary pulmonary hypertension (PH. One current hypothesis suggests that fenfluramine-like medications may act through interactions with the serotonin (5-hydroxytryptamine [5-HT] transporter (5-HTT located on pulmonary artery smooth muscle cells and responsible for the mitogenic action of 5-HT. Anorexigens may contribute to PH by boosting 5-HT levels in the bloodstream, directly stimulating smooth muscle cell growth, or altering 5-HTT expression. We suggest that individuals with a high basal level of 5-HTT expression related to the presence of the long 5-HTT gene promoter variant may be particularly susceptible to one or more of these potential mechanisms of appetite-suppressant-related PH.

Where is Nepal in the nutrition transition?

Science.gov (United States)

Subedi, Yagya Prasad; Marais, Debbi; Newlands, David

2017-03-01

Nutrition transition is rapid in developing countries, but Nepalese transition is relatively unknown. This study aimed to describe nutrition transition in Nepal over the past 40 years by identifying the shifts in the Nepalese diets and nutritional status and the underlying shifts associated with this. Popkin's framework was used to identify shifts in Nepalese diet and the inter-relationship of diet with epidemiological, demographic and economic shifts. The current study used quantitative methodology including secondary data analysis based on food balance sheets, economic surveys and the government databases. The Nepalese diet is shifting away from agricultural staple based foods to modern processed foods with higher total energy, total fat, and sugar. The prevalence of overweight/obesity and diet related non-communicable diseases are increasing. Urbanisation is rapid and nutrition transition already advanced in urban area. The Nepalese economic structure has also changed shifting away from agricultural food supply system towards modern processing based food supply system. These changes in the Nepalese diet are triggered by income and urbanisation. The trade liberalisation has made processed foods, edible oil and sugar easily available at supermarkets and fast food outlets. It is clear that Nepal has now entered into the fourth stage of nutrition transition according to Popkin's framework. As a result, overweight, obesity and the prevalence of many noncommunicable diseases are all rapidly growing. A further study is recommended to identify whether urban versus rural, rich versus poor and educated versus uneducated families are experiencing the transition in similar way.

Against Popperized epidemiology.

Science.gov (United States)

Jacobsen, M

1976-03-01

The recommendation of Popper's philosophy of science should be adopted by epidemiologists is disputed. Reference is made to other authors who have shown that the most constructive elements in Popper's ideas have been advocated by earlier philosophers and have been used in epidemiology without abandoning inductive reasoning. It is argued that Popper's denigration of inductive methods is particularly harmful to epidemiology. Inductive reasoning and statistical inference play a key role in the science; it is suggested that unfamiliarity with these ideas contributes to widespread misunderstanding of the function of epidemiology. Attention is drawn to a common fallacy involving correlations between three random variables. The prevalence of the fallacy may be related to confusion between deductive and inductive logic.

The modulation of neural gain facilitates a transition between functional segregation and integration in the brain.

Science.gov (United States)

Shine, James M; Aburn, Matthew J; Breakspear, Michael; Poldrack, Russell A

2018-01-29

Cognitive function relies on a dynamic, context-sensitive balance between functional integration and segregation in the brain. Previous work has proposed that this balance is mediated by global fluctuations in neural gain by projections from ascending neuromodulatory nuclei. To test this hypothesis in silico, we studied the effects of neural gain on network dynamics in a model of large-scale neuronal dynamics. We found that increases in neural gain directed the network through an abrupt dynamical transition, leading to an integrated network topology that was maximal in frontoparietal 'rich club' regions. This gain-mediated transition was also associated with increased topological complexity, as well as increased variability in time-resolved topological structure, further highlighting the potential computational benefits of the gain-mediated network transition. These results support the hypothesis that neural gain modulation has the computational capacity to mediate the balance between integration and segregation in the brain. © 2018, Shine et al.

Development and application of Human Genome Epidemiology

Science.gov (United States)

Xu, Jingwen

2017-12-01

Epidemiology is a science that studies distribution of diseases and health in population and its influencing factors, it also studies how to prevent and cure disease and promote health strategies and measures. Epidemiology has developed rapidly in recent years and it is an intercross subject with various other disciplines to form a series of branch disciplines such as Genetic epidemiology, molecular epidemiology, drug epidemiology and tumor epidemiology. With the implementation and completion of Human Genome Project (HGP), Human Genome Epidemiology (HuGE) has emerged at this historic moment. In this review, the development of Human Genome Epidemiology, research content, the construction and structure of relevant network, research standards, as well as the existing results and problems are briefly outlined.

Socio-technical transition as a co-evolutionary process: Innovation and the role of niche markets in the transition to motor vehicles

Science.gov (United States)

Birky, Alicia K.

2008-10-01

Significant reductions in greenhouse emissions from personal transportation will require a transition to an alternative technology regime based on renewable energy sources. Two bodies of research, the quasi-evolutionary (QE) model and the multi-level perspective (MLP) assert that processes within niches play a fundamental role in such transitions. This research asks whether the description of transitions based on this niche hypothesis and its underlying assumptions is consistent with the historical U.S. transition to motor vehicles at the beginning of the 20th century. Unique to this dissertation is the combination of the perspective of the entrepreneur with co-evolutionary approaches to socio-technical transitions. This approach is augmented with concepts from the industry life-cycle model and with a taxonomy of mechanisms of learning. Using this analytic framework, I examine specifically the role of entrepreneurial behavior and processes within and among firms in the co-evolution of technologies and institutions during the transition to motor vehicles. I find that niche markets played an important role in the development of the technology, institutions, and the industry. However, I also find that the diffusion of the automobile is not consistent with the niche hypothesis in the following ways: (1) product improvements and cost reductions were not realized in niche markets, but were achieved simultaneously with diffusion into mass markets; (2) in addition to learning-by-doing and learning-by-interacting with users, knowledge spillovers and interacting with suppliers were critical in this process; (3) cost reductions were not automatic results of expanding markets, but rather arose from the strategies of entrepreneurs based on personal perspectives and values. This finding supports the use of a behavioral approach with a micro-focus in the analysis of socio-technical change. I also find that the emergence and diffusion of the motor vehicle can only be understood by

Rejecting the equilibrium-point hypothesis.

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Gottlieb, G L

1998-01-01

The lambda version of the equilibrium-point (EP) hypothesis as developed by Feldman and colleagues has been widely used and cited with insufficient critical understanding. This article offers a small antidote to that lack. First, the hypothesis implicitly, unrealistically assumes identical transformations of lambda into muscle tension for antagonist muscles. Without that assumption, its definitions of command variables R, C, and lambda are incompatible and an EP is not defined exclusively by R nor is it unaffected by C. Second, the model assumes unrealistic and unphysiological parameters for the damping properties of the muscles and reflexes. Finally, the theory lacks rules for two of its three command variables. A theory of movement should offer insight into why we make movements the way we do and why we activate muscles in particular patterns. The EP hypothesis offers no unique ideas that are helpful in addressing either of these questions.

Updating the mild encephalitis hypothesis of schizophrenia.

Science.gov (United States)

Bechter, K

2013-04-05

Schizophrenia seems to be a heterogeneous disorder. Emerging evidence indicates that low level neuroinflammation (LLNI) may not occur infrequently. Many infectious agents with low overall pathogenicity are risk factors for psychoses including schizophrenia and for autoimmune disorders. According to the mild encephalitis (ME) hypothesis, LLNI represents the core pathogenetic mechanism in a schizophrenia subgroup that has syndromal overlap with other psychiatric disorders. ME may be triggered by infections, autoimmunity, toxicity, or trauma. A 'late hit' and gene-environment interaction are required to explain major findings about schizophrenia, and both aspects would be consistent with the ME hypothesis. Schizophrenia risk genes stay rather constant within populations despite a resulting low number of progeny; this may result from advantages associated with risk genes, e.g., an improved immune response, which may act protectively within changing environments, although they are associated with the disadvantage of increased susceptibility to psychotic disorders. Specific schizophrenic symptoms may arise with instances of LLNI when certain brain functional systems are involved, in addition to being shaped by pre-existing liability factors. Prodrome phase and the transition to a diseased status may be related to LLNI processes emerging and varying over time. The variability in the course of schizophrenia resembles the varying courses of autoimmune disorders, which result from three required factors: genes, the environment, and the immune system. Preliminary criteria for subgrouping neurodevelopmental, genetic, ME, and other types of schizophrenias are provided. A rare example of ME schizophrenia may be observed in Borna disease virus infection. Neurodevelopmental schizophrenia due to early infections has been estimated by others to explain approximately 30% of cases, but the underlying pathomechanisms of transition to disease remain in question. LLNI (e.g. from

Glaucoma--diabetes of the brain: a radical hypothesis about its nature and pathogenesis.

Science.gov (United States)

Faiq, Muneeb A; Dada, Rima; Saluja, Daman; Dada, Tanuj

2014-05-01

Glaucoma is the leading cause of irreversible blindness characterized by irremediable loss of retinal ganglion cells. Its risk increases with progressing age and elevated intraocular pressure. Studies have established that glaucoma is a neurodegenerative disorder in which the damage involves many brain tissues from retina to the lateral geniculate nucleus. Despite lot of research, complete pathomechanism of glaucoma is not known and there is no treatment available except modification of intraocular pressure pharmacologically and/or surgically. We here present a hypothesis inspired by studies across many areas of molecular and clinical sciences in an integrative manner that leads to a uniquely unconventional understanding of this disorder. Our hypothesis postulates that glaucoma may possibly be the diabetes of the brain. Based on the remarkable similarities between glaucoma and diabetes we propose glaucoma also to be a type of diabetes. Glaucoma and diabetes share many aspects from various molecular mechanisms to involvement of insulin and possible use of antidiabetics in glaucoma therapy. Additionally, Alzheimer's disease has already been proposed to be diabetes type-3. We show that Alzheimer's disease is cerebral glaucoma and diabetes at the same time which, by transitive property of similarities, again leads to our hypothesis that glaucoma is diabetes of the brain. Our proposition may lead to appreciation of certain important facets of glaucoma which have previously not been given due consideration. It also may lead to an alternative classification of diabetes as pancreatic and brain diabetes thereby widening the vision arena of the understanding of both these disorders. Copyright © 2014 Elsevier Ltd. All rights reserved.

Hypothesis Testing in the Real World

Science.gov (United States)

Miller, Jeff

2017-01-01

Critics of null hypothesis significance testing suggest that (a) its basic logic is invalid and (b) it addresses a question that is of no interest. In contrast to (a), I argue that the underlying logic of hypothesis testing is actually extremely straightforward and compelling. To substantiate that, I present examples showing that hypothesis…

How valid is the prenatal estrogen excess hypothesis of testicular germ cell cancer? A case control study on hormone-related factors.

Science.gov (United States)

Dieckmann, K P; Endsin, G; Pichlmeier, U

2001-12-01

The prenatal estrogen excess hypothesis postulates abnormally high estrogen levels during pregnancy which predispose the developing gonad to testicular germ cell cancer (GCT) in adulthood. As no direct measurements are possible to support this hypothesis, evidence must come from clinical and epidemiological observations. The present study looked to surrogate parameters that purportedly point to high estrogenic influence in utero. In a case-control study design, 418 cases with GCT were compared to 636 controls having fractures, injuries or nephrolithiasis. A second comparison was done with 120 men suffering from malignant melanoma. The following factors were investigated: maternal and paternal age at birth of proband, birth-order, distribution of brothers and sisters in sibs of patients, sibship size, status of being a twin, status of being a singleton child, handedness, and frequency of breast cancer in mothers and sisters. Status of being a twin was significantly associated with GCT risk (OR 2.41; 95% CI 1.04- 5.63) if compared to men with fractures or stones. Comparison with melanoma controls showed only a nonsignificant trend. Frequency of breast cancer was insignificantly higher in mothers of GCT patients. Maternal age above 30 years was associated with decreased risk of GCT, which is contradictory to the hypothesis. No other parameter was significantly different in cases and controls. The present investigation failed to produce evidence for the estrogen excess hypothesis. Obviously, the parameters tested are only weak indicators of estrogenic influence during embryogenesis. Thus, the sample size and statistical power of the trial might have been too low to show any significant association. But, assessing the negative results of this study in light of equally negative results in previous investigations, the estrogen excess hypothesis still remains to be hypothetic.

Transition state structures in solution

International Nuclear Information System (INIS)

Bertran, J.; Lluch, J. M.; Gonzalez-Lafont, A.; Dillet, V.; Perez, V.

1995-01-01

In the present paper the location of transition state structures for reactions in solution has been studied. Continuum model calculations have been carried out on the Friedel-Crafts alkylation reaction and a proton transfer through a water molecule between two oxygen atoms in formic acid. In this model the separation between the chemical system and the solvent has been introduced. On the other hand, the discrete Monte Carlo methodology has also been used to simulate the solvent effect on dissociative electron transfer processes. In this model, the hypothesis of separability is not assumed. Finally, the validity of both approaches is discussed

The contribution of epidemiology

NARCIS (Netherlands)

Brandt, P. van den; Voorrips, L.; Hertz-Picciotto, I.; Shuker, D.; Boeing, H.; Speijers, G.; Guittard, C.; Kleiner, J.; Knowles, M.; Wolk, A.; Goldbohm, A.

2002-01-01

Epidemiologic studies directly contribute data on risk (or benefit) in humans as the investigated species, and in the full food intake range normally encountered by humans. This paper starts with introducing the epidemiologic approach, followed by a discussion of perceived differences between

The atomic hypothesis: physical consequences

International Nuclear Information System (INIS)

Rivas, Martin

2008-01-01

The hypothesis that matter is made of some ultimate and indivisible objects, together with the restricted relativity principle, establishes a constraint on the kind of variables we are allowed to use for the variational description of elementary particles. We consider that the atomic hypothesis not only states the indivisibility of elementary particles, but also that these ultimate objects, if not annihilated, cannot be modified by any interaction so that all allowed states of an elementary particle are only kinematical modifications of any one of them. Therefore, an elementary particle cannot have excited states. In this way, the kinematical group of spacetime symmetries not only defines the symmetries of the system, but also the variables in terms of which the mathematical description of the elementary particles can be expressed in either the classical or the quantum mechanical description. When considering the interaction of two Dirac particles, the atomic hypothesis restricts the interaction Lagrangian to a kind of minimal coupling interaction

Epidemiology and Radiation Protection

International Nuclear Information System (INIS)

1987-01-01

Epidemiology aims at providing direct evidence of the long term health effects in humans due to potentially dangerous exposures to various nuisance agents, including ionising radiation. Inappropriate interpretation and use of the results of epidemiological studies may result in inaccurate assessments of the risks associated with radiation exposure. This report presents the proceedings of a Workshop organised by the NEA to create an opportunity for epidemiologists and radiation protection specialists to exchange their experiences and views on the problems of methodology in epidemiological research and on the application of its results to the assessment of radiation risks

16 CFR 1000.26 - Directorate for Epidemiology.

Science.gov (United States)

2010-01-01

... 16 Commercial Practices 2 2010-01-01 2010-01-01 false Directorate for Epidemiology. 1000.26... AND FUNCTIONS § 1000.26 Directorate for Epidemiology. The Directorate for Epidemiology, managed by the Associate Executive Director for Epidemiology, is responsible for the collection and analysis of data on...

[Scientific, practical and educational aspects of clinical epidemiology].

Science.gov (United States)

Briko, N I

2012-01-01

This article defines clinical epidemiology and describes its goal and objectives. The author claims that clinical epidemiology is a section of epidemiology which underlies the development of evidence-based standards for diagnostics, treatment and prevention and helps to select the appropriate algorithm for each clinical case. The study provides a comprehensive overview of the relationship between clinical epidemiology and evidence-based medicine. Epidemiological research is shown to be methodological basis of clinical epidemiology and evidence-based medicine with randomized controlled trials being the "gold standard" for obtaining reliable data. The key stages in the history of clinical epidemiology are discussed and further development of clinical epidemiology and the integration of courses on clinical epidemiology in education is outlined for progress in medical research and health care practice.

Male reproduction and environmental and occupational exposures: a review of epidemiologic methods

Directory of Open Access Journals (Sweden)

Golden Anne L.

1999-01-01

Full Text Available Concerns that chemical exposures in the environment have been detrimental to male sexual development and fertility have been heightened by reports of declining sperm counts over the past 50 years. Marked geographic variation has been found in semen quality and in the incidence of testicular cancer and certain urogenital defects. Debate continues over the existence, magnitude and significance of these trends, and how best to evaluate the hypothesis that in utero and childhood exposures to estrogenic compounds may be to blame. Epidemiologic methods for assessing the impact of hazardous substances on male reproductive health have been developed mainly in the area of occupational medicine, and this paper will review the currently recommended methods. These include questionnaires to determine reproductive history and sexual function; reproductive hormone profiles; and semen analyses such as sperm concentration, motility, and morphology. New research tools that show significant promise from the fields of clinical reproductive medicine and reproductive toxicology are discussed as possible additions to epidemiologic studies, including assays of sperm function and genetic integrity, and biomarkers of DNA damage. For population-based studies involving occupational groups or communities with environmental exposures, issues related to the cost, validity, precision and utility of these methods must be carefully considered.

Leadership of the Department of Epidemiology of the Johns Hopkins Bloomberg School of Public Health in Its First Century.

Science.gov (United States)

Celentano, David D

2016-03-01

This commentary reviews the contributions of each of the 7 Chairs of the Department of Epidemiology from the Department's inception in 1919 to the advent of the Centennial Celebration of the Johns Hopkins Bloomberg School of Public Health in 2016. The founding Chair, Wade Hampton Frost (1919-1938), was among the handful of foundational thinkers in the discipline of epidemiology. Kenneth Maxcy (1938-1954) and Philip Sartwell (1954-1970) oversaw the Department through the epidemiologic transition from a preponderance of morbidity and mortality due to infectious diseases to a preponderance of noncommunicable diseases. Abraham Lilienfeld (1970-1975) and Leon Gordis (1975-1993) were perhaps best known for their mastery of teaching, influencing generations of both medical and public health students. Jonathan Samet (1994-2008) oversaw a major curriculum revision and expanded the Department significantly, and David Celentano (2008-) is working to rebalance the practice of epidemiology with the etiological foundations of epidemiology. All Chairs were a product of their times, and their research focus and portfolios influenced the direction of the Department. Future generations of Johns Hopkins students will be influenced directly or indirectly by the heritage of these Chairs' actions and those of their faculty. © The Author 2016. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Non-linear education gradient across the nutrition transition: mothers’ overweight and the population education transition

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Salinas, Daniel; Baker, David P

2015-01-01

transition” (PET) curve hypothesis about how education influences on health risks are contextualized across population transitions. PMID:26054756

History and philosophy of modern epidemiology

DEFF Research Database (Denmark)

Andersen, Hanne

2012-01-01

Epidemiological studies of chronic diseases began around the mid-20th century. Contrary to the infectious disease epidemiology which had prevailed at the beginning of the 20th century and which had focused on single agents causing individual diseases, the chronic disease epidemiology which emerge...

Multiple sclerosis: a geographical hypothesis.

Science.gov (United States)

Carlyle, I P

1997-12-01

Multiple sclerosis remains a rare neurological disease of unknown aetiology, with a unique distribution, both geographically and historically. Rare in equatorial regions, it becomes increasingly common in higher latitudes; historically, it was first clinically recognized in the early nineteenth century. A hypothesis, based on geographical reasoning, is here proposed: that the disease is the result of a specific vitamin deficiency. Different individuals suffer the deficiency in separate and often unique ways. Evidence to support the hypothesis exists in cultural considerations, in the global distribution of the disease, and in its historical prevalence.

The Epidemiology of Obesity: A Big Picture

Science.gov (United States)

Hruby, Adela; Hu, Frank B.

2016-01-01

The epidemic of overweight and obesity presents a major challenge to chronic disease prevention and health across the life course around the world. Fueled by economic growth, industrialization, mechanized transport, urbanization, an increasingly sedentary lifestyle, and a nutritional transition to processed foods and high calorie diets over the last 30 years, many countries have witnessed the prevalence of obesity in its citizens double, and even quadruple. Rising prevalence of childhood obesity, in particular, forebodes a staggering burden of disease in individuals and healthcare systems in the decades to come. A complex, multifactorial disease, with genetic, behavioral, socioeconomic, and environmental origins, obesity raises risk of debilitating morbidity and mortality. Relying primarily on epidemiologic evidence published within the last decade, this non-exhaustive review discusses the extent of the obesity epidemic, its risk factors—known and novel—, sequelae, and economic impact across the globe. PMID:25471927

A NONPARAMETRIC HYPOTHESIS TEST VIA THE BOOTSTRAP RESAMPLING

OpenAIRE

Temel, Tugrul T.

2001-01-01

This paper adapts an already existing nonparametric hypothesis test to the bootstrap framework. The test utilizes the nonparametric kernel regression method to estimate a measure of distance between the models stated under the null hypothesis. The bootstraped version of the test allows to approximate errors involved in the asymptotic hypothesis test. The paper also develops a Mathematica Code for the test algorithm.

Epidemiologic studies of radioactively contaminated environments and cancer clusters

International Nuclear Information System (INIS)

Boice, J.D. Jr.

1991-01-01

This paper reports on epidemiologic studies which address the distribution and determinants of disease in human populations. Investigations of the possible adverse effects of living in radioactively contaminated environments are difficult to conduct, however, because human populations tend to be fairly mobile, cumulative exposures to individuals from environmental conditions are difficult to estimate, and the risks associated with such exposures tend to be small relative to background levels of disease. Such studies can be arbitrarily classified as geographic correlation surveys, analytic studies, and cluster evaluations. Geographic correlation studies (ecological surveys) relate disease in populations to area characteristics. Although exposure to individuals is unknown, these exploratory or hypothesis-generating studies can identify areas to target for further in-depth evaluation. Analytic investigations relate individual exposure information to disease occurrence. Unusual occurrences of disease in time and place (clusters) occasionally point to a common environmental factor; cluster evaluations have been most successful in identifying the source of infectious disease outbreaks

Globalization and local response to epidemiological overlap in 21st century Ecuador

Directory of Open Access Journals (Sweden)

Waters William F

2006-05-01

Full Text Available Abstract Background Third World countries are confronted by a complex overlay of two sets of health problems. Traditional maladies, including communicable diseases, malnutrition, and environmental health hazards coexist with emerging health challenges, including cardiovascular disease, cancer, and increasing levels of obesity. Using Ecuador as an example, this paper proposes a conceptual framework for linking epidemiologic overlap to emerging social structures and processes at the national and global levels. Discussion Epidemiologic trends can be seen as part of broader processes related to globalization, but this does not imply that globalization is a monolithic force that inevitably and uniformly affects nations, communities, and households in the same manner. Rather, characteristics and forms of social organization at the subnational level can shape the way that globalization takes place. Thus, globalization has affected Ecuador in specific ways and is, at the same time, intimately related to the form in which the epidemiologic transition has transpired in that country. Summary Ecuador is among neither the poorest nor the wealthiest countries and its situation may illuminate trends in other parts of the world. As in other countries, insertion into the global economy has not taken place in a vacuum; rather, Ecuador has experienced unprecedented social and demographic change in the past several decades, producing profound transformation in its social structure. Examples of local represent alternatives to centralized health systems that do not effectively address the complex overlay of traditional and emerging health problems.

The thrifty phenotype hypothesis revisited

DEFF Research Database (Denmark)

Vaag, A A; Grunnet, L G; Arora, G P

2012-01-01

Twenty years ago, Hales and Barker along with their co-workers published some of their pioneering papers proposing the 'thrifty phenotype hypothesis' in Diabetologia (4;35:595-601 and 3;36:62-67). Their postulate that fetal programming could represent an important player in the origin of type 2...... of the underlying molecular mechanisms. Type 2 diabetes is a multiple-organ disease, and developmental programming, with its idea of organ plasticity, is a plausible hypothesis for a common basis for the widespread organ dysfunctions in type 2 diabetes and the metabolic syndrome. Only two among the 45 known type 2...

Testing of Frank's hypothesis on a containerless packing of macroscopic soft spheres and comparison with mono-atomic metallic liquids

International Nuclear Information System (INIS)

Sahu, K.K.; Wessels, V.; Kelton, K.F.; Loeffler, J.F.

2011-01-01

Highlights: → Testing of Frank's hypothesis for Centripetal Packing (CP) has been proposed. → It is shown that CP is an idealized model for Monatomic Supercooled Liquid (MSL). → The CP is fit for comparing with studies on MSL in a containerless environment. → We measure local orders in CP by HA and BOO methods for the first time. → It is shown that icosahedral order is greater in CP than MSL and reasons explored. - Abstract: It is well-known that metallic liquids can exist below their equilibrium melting temperature for a considerable time. To explain this, Frank proposed that icosahedral ordering, incompatible with crystalline long-range order, is prevalent in the atomic structure of these liquids, stabilizing them and enabling them to be supercooled. Some studies of the atomic structures of metallic liquids using Beam-line Electrostatic Levitation (BESL; containerless melting), and other techniques, support this hypothesis . Here we examine Frank's hypothesis in a system of macroscopic, monodisperse deformable spheres obtained by containerless packing under the influence of centripetal force. The local structure of this packing is analyzed and compared with atomic ensembles of liquid transition metals obtained by containerless melting using the BESL method.

Desafíos a la epidemiología (pasos para una epidemiología "Miltoniana" Challenges to epidemiology (steps to a "Miltonian" epidemiology

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Juan Samaja

2003-06-01

Full Text Available Se sostiene que uno de los grandes desafíos que enfrenta la Epidemiología contemporánea está situado en el campo teórico, y consiste esencialmente en la exigencia de revisar la conceptualización del objeto de la epidemiología dominante que reduce la salud de las poblaciones al comportamiento de los riesgos concebidos con abstracción de los vínculos particulares que los sujetos guardan con sus corporeidades geográficas y medioambientales. El artículo pretende reintroducir la perspectiva dialéctica que deja de lado la visión sustancialista de la realidad de las poblaciones de un lado y del medio ambiente, del otro lado, para proponer una visión estructural, funcional e histórica de ambos conceptos, desarrollando, en este sentido el espíritu de la obra del Gran Geógrafo Brasileiro.This paper argues that one of the major challenges that contemporary Epidemiology has to face is at the level of theory. In essence, it is necessary to revise the abstract conceptualization of the dominant Epidemiology object, which has reduced the health of the population to behavioral risks, without taking into account the link that people have to their geographical and environmental corporities. This article then seeks to reinsert the dialectical perspective that leaves aside the substantialist view of population reality, on one side, and that of the environment, on the other, in order to propose a structural, functional and historical perspective of both concepts, developing, in this way, the spirit of the Great Brazilian Geographer's work.

Error probabilities in default Bayesian hypothesis testing

NARCIS (Netherlands)

Gu, Xin; Hoijtink, Herbert; Mulder, J,

2016-01-01

This paper investigates the classical type I and type II error probabilities of default Bayes factors for a Bayesian t test. Default Bayes factors quantify the relative evidence between the null hypothesis and the unrestricted alternative hypothesis without needing to specify prior distributions for

Renal damage mediated by oxidative stress: a hypothesis of protective effects of red wine.

Science.gov (United States)

Rodrigo, Ramón; Rivera, Gonzalo

2002-08-01

Over the last decade, oxidative stress has been implicated in the pathogenesis of a wide variety of seemingly unrelated renal diseases. Epidemiological studies have documented an association of moderate wine consumption with a decreased risk of cardiovascular and neurological diseases; however, similar studies in the kidney are still lacking. The kidney is an organ highly vulnerable to damage caused by reactive oxygen species (ROS), likely due to the abundance of polyunsaturated fatty acids in the composition of renal lipids. ROS are involved in the pathogenic mechanism of conditions such as glomerulosclerosis and tubulointerstitial fibrosis. The health benefits of moderate consumption of red wine can be partly attributed to its antioxidant properties. Indeed, the kidney antioxidant defense system is enhanced after chronic exposure to moderate amounts of wine, a response arising from the combined effects of ethanol and the nonalcoholic components, mainly polyphenols. Polyphenols behave as potent ROS scavengers and metal chelators; ethanol, in turn, modulates the activity of antioxidant enzymes. Therefore, a hypothesis that red wine causes a decreased vulnerability of the kidney to the oxidative challenges could be proposed. This view is partly supported by direct evidences indicating that wine and antioxidants isolated from red wine, as well as other antioxidants, significantly attenuate or prevent the oxidative damage to the kidney. The present hypothesis paper provides a collective body of evidence suggesting a protective role of moderate wine consumption against the production and progression of renal diseases, based on the existing concepts on the pathophysiology of kidney injury mediated by oxidative stress.

Aminoglycoside antibiotics and autism: a speculative hypothesis

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Manev Hari

2001-10-01

Full Text Available Abstract Background Recently, it has been suspected that there is a relationship between therapy with some antibiotics and the onset of autism; but even more curious, some children benefited transiently from a subsequent treatment with a different antibiotic. Here, we speculate how aminoglycoside antibiotics might be associated with autism. Presentation We hypothesize that aminoglycoside antibiotics could a trigger the autism syndrome in susceptible infants by causing the stop codon readthrough, i.e., a misreading of the genetic code of a hypothetical critical gene, and/or b improve autism symptoms by correcting the premature stop codon mutation in a hypothetical polymorphic gene linked to autism. Testing Investigate, retrospectively, whether a link exists between aminoglycoside use (which is not extensive in children and the onset of autism symptoms (hypothesis "a", or between amino glycoside use and improvement of these symptoms (hypothesis "b". Whereas a prospective study to test hypothesis "a" is not ethically justifiable, a study could be designed to test hypothesis "b". Implications It should be stressed that at this stage no direct evidence supports our speculative hypothesis and that its main purpose is to initiate development of new ideas that, eventually, would improve our understanding of the pathobiology of autism.

The impact of parenthood on environmental attitudes and behaviour: a longitudinal investigation of the legacy hypothesis.

Science.gov (United States)

Thomas, Gregory O; Fisher, Rose; Whitmarsh, Lorraine; Milfont, Taciano L; Poortinga, Wouter

2018-01-01

Willingness to engage in sustainable actions may be limited by the psychological distance of climate change. In this study, we test the legacy hypothesis , which holds that having children leads parents to consider the legacy left to offspring in respect of environmental quality. Using the Understanding Society dataset, a longitudinal survey representative of the UK population ( n  = 18,176), we assess how having children may change people's individual environmental attitudes and behaviour. Results indicate that having a new child is associated with a small decrease in the frequency of a few environmental behaviours. Only parents with already high environmental concern show a small increase in the desire to act more sustainably after the birth of their first child. Overall, the results do not provide evidence in support of the legacy hypothesis in terms of individual-level environmental attitudes and behaviours. We argue that the transition to parenthood is a time where concern is prioritised on the immediate wellbeing of the child and not on the future environmental threats.

Biostatistics series module 2: Overview of hypothesis testing

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Avijit Hazra

2016-01-01

Full Text Available Hypothesis testing (or statistical inference is one of the major applications of biostatistics. Much of medical research begins with a research question that can be framed as a hypothesis. Inferential statistics begins with a null hypothesis that reflects the conservative position of no change or no difference in comparison to baseline or between groups. Usually, the researcher has reason to believe that there is some effect or some difference which is the alternative hypothesis. The researcher therefore proceeds to study samples and measure outcomes in the hope of generating evidence strong enough for the statistician to be able to reject the null hypothesis. The concept of the P value is almost universally used in hypothesis testing. It denotes the probability of obtaining by chance a result at least as extreme as that observed, even when the null hypothesis is true and no real difference exists. Usually, if P is < 0.05 the null hypothesis is rejected and sample results are deemed statistically significant. With the increasing availability of computers and access to specialized statistical software, the drudgery involved in statistical calculations is now a thing of the past, once the learning curve of the software has been traversed. The life sciences researcher is therefore free to devote oneself to optimally designing the study, carefully selecting the hypothesis tests to be applied, and taking care in conducting the study well. Unfortunately, selecting the right test seems difficult initially. Thinking of the research hypothesis as addressing one of five generic research questions helps in selection of the right hypothesis test. In addition, it is important to be clear about the nature of the variables (e.g., numerical vs. categorical; parametric vs. nonparametric and the number of groups or data sets being compared (e.g., two or more than two at a time. The same research question may be explored by more than one type of hypothesis test

Transition from pre-diabetes to diabetes and predictors of risk in Mexican-Americans

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Wu SH

2017-12-01

Full Text Available Shenghui Wu,1 Joseph B McCormick,2 Joanne E Curran,3 Susan P Fisher-Hoch2 1Department of Epidemiology and Biostatistics, University of Texas Health at San Antonio-Laredo Campus, Laredo, 2Division of Epidemiology, University of Texas Health Science Center-Houston, School of Public Health, Brownsville Campus, Brownsville, 3South Texas Diabetes and Obesity Institute, School of Medicine, University of Texas Rio Grande Valley, Brownsville Campus, Brownsville, TX, USA Background: No studies have examined risk factors for the transition from pre-diabetes to diabetes in populations with widespread obesity and diabetes. We determined proximal changes and factors affecting the transition among Mexican-Americans with pre-diabetes.Methods: Participants with pre-diabetes (n=285 were recruited from our randomly sampled population-based Cameron County Hispanic Cohort. These participants were followed for an average of 27 months with repeat examination every 3 to 4 months. Metabolic health was defined as having less than 2 metabolic abnormalities (e.g., hypertension, elevated low-density lipoprotein, etc. Diabetes was identified as fasting blood glucose ≥126 mg/dL, glycated hemoglobin ≥6.5% and/or on hypoglycemic medication.Results: Ninety-six of 285 (33.7% participants transitioned to overt diabetes. The increased risk of diabetes in the metabolically unhealthy varying with follow-up time was 81% (adjusted odds ratio [OR]: 1.81; 95% CI: 1.09–3.02. The risk of diabetes increased 8% for each kg/m2 of increase in body mass index (BMI, OR: 1.08; 95% CI: 1.05–1.11 independent of covariates. Transition to diabetes was accompanied by a mean increase in BMI of 0.28 kg/m2, and deterioration in metabolic health of 9% (OR: 1.09; 95% CI: 1.003–1.18 compared with those who did not transition.Conclusions: Deteriorating metabolic health and/or increasing BMI significantly raises the risk of transitioning from pre-diabetes to diabetes. Transition itself was

Epilepsy in India I: Epidemiology and public health

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Senthil Amudhan

2015-01-01

Full Text Available Of the 70 million persons with epilepsy (PWE worldwide, nearly 12 million PWE are expected to reside in India; which contributes to nearly one-sixth of the global burden. This paper (first of the two part series provides an in-depth understanding of the epidemiological aspects of epilepsy in India for developing effective public health prevention and control programs. The overall prevalence (3.0-11.9 per 1,000 population and incidence (0.2-0.6 per 1,000 population per year data from recent studies in India on general population are comparable to the rates of high-income countries (HICs despite marked variations in population characteristics and study methodologies. There is a differential distribution of epilepsy among various sociodemographic and economic groups with higher rates reported for the male gender, rural population, and low socioeconomic status. A changing pattern in the age-specific occurrence of epilepsy with preponderance towards the older age group is noticed due to sociodemographic and epidemiological transition. Neuroinfections, neurocysticercosis (NCC, and neurotrauma along with birth injuries have emerged as major risk factors for secondary epilepsy. Despite its varied etiology (unknown and known, majority of the epilepsy are manageable in nature. This paper emphasizes the need for focused and targeted programs based on a life-course perspective and calls for a stronger public health approach based on equity for prevention, control, and management of epilepsy in India.

Mastery Learning and the Decreasing Variability Hypothesis.

Science.gov (United States)

Livingston, Jennifer A.; Gentile, J. Ronald

1996-01-01

This report results from studies that tested two variations of Bloom's decreasing variability hypothesis using performance on successive units of achievement in four graduate classrooms that used mastery learning procedures. Data do not support the decreasing variability hypothesis; rather, they show no change over time. (SM)

[Epidemiology, diagnostics, and treatment of complications after neuroinfections: chronic fatigue syndrome].

Science.gov (United States)

Verner, O M; Murashko, N K

2012-01-01

Epidemiology information which testify to prevalence syndrome of chronic ustalostti (SV) is resulted in the article, and from some data this diagnosis is covered at more than 20% patients which carried neyroinfection. SV meets more frequent only in age 40-59, thus for women a disease is marked in 4 times more frequent, than for men. Today etiology of disease remains unknown, but the value of genetic, immunological factors, pathogens, neurogenic violations and features of feed is examined. Possibility of infectious etiology SV causes considerable interest of researchers, but at first this syndrome was examined as a sharp viral infection, where the most reliable exciter is consider the virus of Epshteyna-barr. Using of intravenous introduction of globulin for SV carries experimental character and grounded on a hypothesis about immunological or infectious etiology of this disease.

The linear hypothesis and radiation carcinogenesis

International Nuclear Information System (INIS)

Roberts, P.B.

1981-10-01

An assumption central to most estimations of the carcinogenic potential of low levels of ionising radiation is that the risk always increases in direct proportion to the dose received. This assumption (the linear hypothesis) has been both strongly defended and attacked on several counts. It appears unlikely that conclusive, direct evidence on the validity of the hypothesis will be forthcoming. We review the major indirect arguments used in the debate. All of them are subject to objections that can seriously weaken their case. In the present situation, retention of the linear hypothesis as the basis of extrapolations from high to low dose levels can lead to excessive fears, over-regulation and unnecessarily expensive protection measures. To offset these possibilities, support is given to suggestions urging a cut-off dose, probably some fraction of natural background, below which risks can be deemed acceptable

Erasing no-man’s land by thermodynamically stabilizing the liquid-liquid transition in tetrahedral particles

Science.gov (United States)

Smallenburg, Frank; Filion, Laura; Sciortino, Francesco

2014-09-01

One of the most controversial hypotheses for explaining the origin of the thermodynamic anomalies characterizing liquid water postulates the presence of a metastable second-order liquid-liquid critical point located in the `no-man’s land’. In this scenario, two liquids with distinct local structure emerge near the critical temperature. Unfortunately, as spontaneous crystallization is rapid in this region, experimental support for this hypothesis relies on significant extrapolations, either from the metastable liquid or from amorphous solid water. Although the liquid-liquid transition is expected to feature in many tetrahedrally coordinated liquids, including silicon, carbon and silica, even numerical studies of atomic and molecular models have been unable to conclusively prove the existence of this transition. Here we provide such evidence for a model in which it is possible to continuously tune the softness of the interparticle interaction and the flexibility of the bonds, the key ingredients controlling the existence of the critical point. We show that conditions exist where the full coexistence is thermodynamically stable with respect to crystallization. Our work offers a basis for designing colloidal analogues of water exhibiting liquid-liquid transitions in equilibrium, opening the way for experimental confirmation of the original hypothesis.

Is PMI the Hypothesis or the Null Hypothesis?

Science.gov (United States)

Tarone, Aaron M; Sanford, Michelle R

2017-09-01

Over the past several decades, there have been several strident exchanges regarding whether forensic entomologists estimate the postmortem interval (PMI), minimum PMI, or something else. During that time, there has been a proliferation of terminology reflecting this concern regarding "what we do." This has been a frustrating conversation for some in the community because much of this debate appears to be centered on what assumptions are acknowledged directly and which are embedded within a list of assumptions (or ignored altogether) in the literature and in case reports. An additional component of the conversation centers on a concern that moving away from the use of certain terminology like PMI acknowledges limitations and problems that would make the application of entomology appear less useful in court-a problem for lawyers, but one that should not be problematic for scientists in the forensic entomology community, as uncertainty is part of science that should and can be presented effectively in the courtroom (e.g., population genetic concepts in forensics). Unfortunately, a consequence of the way this conversation is conducted is that even as all involved in the debate acknowledge the concerns of their colleagues, parties continue to talk past one another advocating their preferred terminology. Progress will not be made until the community recognizes that all of the terms under consideration take the form of null hypothesis statements and that thinking about "what we do" as a null hypothesis has useful legal and scientific ramifications that transcend arguments over the usage of preferred terminology. © The Authors 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Negative thermal expansion near two structural quantum phase transitions

Energy Technology Data Exchange (ETDEWEB)

Occhialini, Connor A.; Handunkanda, Sahan U.; Said, Ayman; Trivedi, Sudhir; Guzmán-Verri, G. G.; Hancock, Jason N.

2017-12-01

Recent experimental work has revealed that the unusually strong, isotropic structural negative thermal expansion in cubic perovskite ionic insulator ScF3 occurs in excited states above a ground state tuned very near a structural quantum phase transition, posing a question of fundamental interest as to whether this special circumstance is related to the anomalous behavior. To test this hypothesis, we report an elastic and inelastic x-ray scattering study of a second system Hg2I2 also tuned near a structural quantum phase transition while retaining stoichiometric composition and high crystallinity. We find similar behavior and significant negative thermal expansion below 100 K for dimensions along the body-centered-tetragonal c axis, bolstering the connection between negative thermal expansion and zero-temperature structural transitions.We identify the common traits between these systems and propose a set of materials design principles that can guide discovery of newmaterials exhibiting negative thermal expansion

The Lehman Sisters Hypothesis

NARCIS (Netherlands)

I.P. van Staveren (Irene)

2014-01-01

markdownabstract__Abstract__ This article explores the Lehman Sisters Hypothesis. It reviews empirical literature about gender differences in behavioral, experimental, and neuro-economics as well as in other fields of behavioral research. It discusses gender differences along three dimensions of

Comparison between response dynamics in transition economies and developed economies

Science.gov (United States)

Tenenbaum, Joel; Horvatić, Davor; Bajić, Slavica Cosović; Pehlivanović, Bećo; Podobnik, Boris; Stanley, H. Eugene

2010-10-01

In developed economies, the sign of the price increment influences the volatility in an asymmetric fashion—negative increments tend to result in larger volatility (increments with larger magnitudes), while positive increments result in smaller volatility. We explore whether this asymmetry extends from developed economies to European transition economies and, if so, how such asymmetry changes over time as these transition economies develop and mature. We analyze eleven European transition economies and compare the results with those obtained by analyzing U.S. market indices. Specifically, we calculate parameters that quantify both the volatility asymmetry and the strength of its dependence on prior increments. We find that, like their developed economy counterparts, almost all transition economy indices exhibit a significant volatility asymmetry, and the parameter γ characterizing asymmetry fluctuates more over time for transition economies. We also investigate how the association between volatility and volatility asymmetry varies by type of market. We test the hypothesis of a negative correlation between volatility and volatility asymmetry. We find that, for developed economies, γ experiences local minima during (i) “Black Monday” on October 19, 1987, (ii) the dot-com bubble crash in 2002, and (iii) the 2007-2009 global crisis while for transition economies, γ experiences local maxima during times of economic crisis.

Current practice of epidemiology in Africa: highlights of the 3rd conference of the African epidemiological association and 1st conference of the Cameroon society of epidemiology, Yaoundé, Cameroon, 2014.

Science.gov (United States)

Nkwescheu, Armand Seraphin; Fokam, Joseph; Tchendjou, Patrice; Nji, Akindeh; Ngouakam, Hermann; Andre, Bita Fouda; Joelle, Sobngwi; Uzochukwu, Benjamin; Akinroye, Kingsley; Mbacham, Wilfred; Colizzi, Vittorio; Leke, Rose; Victora, Cesar

2015-01-01

As the study of disease occurrence and health indicators in human populations, Epidemiology is a dynamic field that evolves with time and geographical context. In order to update African health workers on current epidemiological practices and to draw awareness of early career epidemiologists on concepts and opportunities in the field, the 3(rd) African Epidemiology Association and the 1st Cameroon Society of Epidemiology Conference was organized in June 2-6, 2014 at the Yaoundé Mont Febe Hotel, in Cameroon. Under the theme«Practice of Epidemiology in Africa: Stakes, Challenges and Perspectives», the conference attracted close to five hundred guest and participants from all continents. The two main programs were the pre-conference course for capacity building of African Early Career epidemiologists, and the conference itself, providing a forum for scientific exchanges on recent epidemiological concepts, encouraging the use of epidemiological methods in studying large disease burden and neglected tropical diseases; and highlighting existing opportunities.

Whiplash and the compensation hypothesis.

Science.gov (United States)

Spearing, Natalie M; Connelly, Luke B

2011-12-01

Review article. To explain why the evidence that compensation-related factors lead to worse health outcomes is not compelling, either in general, or in the specific case of whiplash. There is a common view that compensation-related factors lead to worse health outcomes ("the compensation hypothesis"), despite the presence of important, and unresolved sources of bias. The empirical evidence on this question has ramifications for the design of compensation schemes. Using studies on whiplash, this article outlines the methodological problems that impede attempts to confirm or refute the compensation hypothesis. Compensation studies are prone to measurement bias, reverse causation bias, and selection bias. Errors in measurement are largely due to the latent nature of whiplash injuries and health itself, a lack of clarity over the unit of measurement (specific factors, or "compensation"), and a lack of appreciation for the heterogeneous qualities of compensation-related factors and schemes. There has been a failure to acknowledge and empirically address reverse causation bias, or the likelihood that poor health influences the decision to pursue compensation: it is unclear if compensation is a cause or a consequence of poor health, or both. Finally, unresolved selection bias (and hence, confounding) is evident in longitudinal studies and natural experiments. In both cases, between-group differences have not been addressed convincingly. The nature of the relationship between compensation-related factors and health is unclear. Current approaches to testing the compensation hypothesis are prone to several important sources of bias, which compromise the validity of their results. Methods that explicitly test the hypothesis and establish whether or not a causal relationship exists between compensation factors and prolonged whiplash symptoms are needed in future studies.

Impact of Insurance Market on Economic Growth in Post-Transition Countries

Directory of Open Access Journals (Sweden)

Phutkaradze Jaba

2014-12-01

Full Text Available The purpose of this work is to identify whether the development of an insurance market is linked to economic growth in former transition countries. A multiple regression analysis is employed to estimate the insurance-growth relationship, using a cross-country panel dataset analysis tracking annual total insurance penetration in 10 countries over the 2000-2012 period, and applying a fixed effect model to test the hypothesis that this linkage is demonstrably positive. The results show a negative and statistically non-significant correlation between insurance and GDP growth, suggesting a lack of evidence that insurance promotes economic growth in post-transition economies.

Do cortical midline variability and low frequency fluctuations mediate William James' "Stream of Consciousness"? "Neurophenomenal Balance Hypothesis" of "Inner Time Consciousness".

Science.gov (United States)

Northoff, Georg

2014-11-01

William James famously characterized consciousness by 'stream of consciousness' which describes the temporal continuity and flow of the contents of consciousness in our 'inner time consciousness'. More specifically he distinguished between "substantive parts", the contents of consciousness, and "transitive parts", the linkages between different contents. While much research has recently focused on the substantive parts, the neural mechanisms underlying the transitive parts and their characterization by the balance between 'sensible continuity' and 'continuous change' remain unclear. The aim of this paper is to develop so-called neuro-phenomenal hypothesis about specifically the transitive parts and their two phenomenal hallmark features, sensible continuity and continuous change in 'inner time consciousness'. Based on recent findings, I hypothesize that the cortical midline structures and their high degree of variability and strong low frequency fluctuations play an essential role in mediating the phenomenal balance between sensible continuity and continuous change. Copyright © 2014 Elsevier Inc. All rights reserved.

The Hypothesis-Driven Physical Examination.

Science.gov (United States)

Garibaldi, Brian T; Olson, Andrew P J

2018-05-01

The physical examination remains a vital part of the clinical encounter. However, physical examination skills have declined in recent years, in part because of decreased time at the bedside. Many clinicians question the relevance of physical examinations in the age of technology. A hypothesis-driven approach to teaching and practicing the physical examination emphasizes the performance of maneuvers that can alter the likelihood of disease. Likelihood ratios are diagnostic weights that allow clinicians to estimate the post-probability of disease. This hypothesis-driven approach to the physical examination increases its value and efficiency, while preserving its cultural role in the patient-physician relationship. Copyright © 2017 Elsevier Inc. All rights reserved.

Discussion of the Porter hypothesis

International Nuclear Information System (INIS)

1999-11-01

In the reaction to the long-range vision of RMNO, published in 1996, The Dutch government posed the question whether a far-going and progressive modernization policy will lead to competitive advantages of high-quality products on partly new markets. Such a question is connected to the so-called Porter hypothesis: 'By stimulating innovation, strict environmental regulations can actually enhance competitiveness', from which statement it can be concluded that environment and economy can work together quite well. A literature study has been carried out in order to determine under which conditions that hypothesis is endorsed in the scientific literature and policy documents. Recommendations are given for further studies. refs

An animated depiction of major depression epidemiology

Directory of Open Access Journals (Sweden)

Patten Scott B

2007-06-01

Full Text Available Abstract Background Epidemiologic estimates are now available for a variety of parameters related to major depression epidemiology (incidence, prevalence, etc.. These estimates are potentially useful for policy and planning purposes, but it is first necessary that they be synthesized into a coherent picture of the epidemiology of the condition. Several attempts to do so have been made using mathematical modeling procedures. However, this information is not easy to communicate to users of epidemiological data (clinicians, administrators, policy makers. Methods In this study, up-to-date data on major depression epidemiology were integrated using a discrete event simulation model. The mathematical model was animated in Virtual Reality Modeling Language (VRML to create a visual, rather than mathematical, depiction of the epidemiology. Results Consistent with existing literature, the model highlights potential advantages of population health strategies that emphasize access to effective long-term treatment. The paper contains a web-link to the animation. Conclusion Visual animation of epidemiological results may be an effective knowledge translation tool. In clinical practice, such animations could potentially assist with patient education and enhanced long-term compliance.

An animated depiction of major depression epidemiology.

Science.gov (United States)

Patten, Scott B

2007-06-08

Epidemiologic estimates are now available for a variety of parameters related to major depression epidemiology (incidence, prevalence, etc.). These estimates are potentially useful for policy and planning purposes, but it is first necessary that they be synthesized into a coherent picture of the epidemiology of the condition. Several attempts to do so have been made using mathematical modeling procedures. However, this information is not easy to communicate to users of epidemiological data (clinicians, administrators, policy makers). In this study, up-to-date data on major depression epidemiology were integrated using a discrete event simulation model. The mathematical model was animated in Virtual Reality Modeling Language (VRML) to create a visual, rather than mathematical, depiction of the epidemiology. Consistent with existing literature, the model highlights potential advantages of population health strategies that emphasize access to effective long-term treatment. The paper contains a web-link to the animation. Visual animation of epidemiological results may be an effective knowledge translation tool. In clinical practice, such animations could potentially assist with patient education and enhanced long-term compliance.

Epidemiology of Recurrent Acute and Chronic Pancreatitis: Similarities and Differences.

Science.gov (United States)

Machicado, Jorge D; Yadav, Dhiraj

2017-07-01

Emerging data in the past few years suggest that acute, recurrent acute (RAP), and chronic pancreatitis (CP) represent a disease continuum. This review discusses the similarities and differences in the epidemiology of RAP and CP. RAP is a high-risk group, comprised of individuals at varying risk of progression. The premise is that RAP is an intermediary stage in the pathogenesis of CP, and a subset of RAP patients during their natural course transition to CP. Although many clinical factors have been identified, accurately predicting the probability of disease course in individual patients remains difficult. Future studies should focus on providing more precise estimates of the risk of disease transition in a cohort of patients, quantification of clinical events during the natural course of disease, and discovery of biomarkers of the different stages of the disease continuum. Availability of clinically relevant endpoints and linked biomarkers will allow more accurate prediction of the natural course of disease over intermediate- or long-term-based characteristics of an individual patient. These endpoints will also provide objective measures for use in clinical trials of interventions that aim to alter the natural course of disease.

Multi-locus sequence typing provides epidemiological insights for diseased sharks infected with fungi belonging to the Fusarium solani species complex.

Science.gov (United States)

Desoubeaux, Guillaume; Debourgogne, Anne; Wiederhold, Nathan P; Zaffino, Marie; Sutton, Deanna; Burns, Rachel E; Frasca, Salvatore; Hyatt, Michael W; Cray, Carolyn

2018-07-01

Fusarium spp. are saprobic moulds that are responsible for severe opportunistic infections in humans and animals. However, we need epidemiological tools to reliably trace the circulation of such fungal strains within medical or veterinary facilities, to recognize environmental contaminations that might lead to infection and to improve our understanding of factors responsible for the onset of outbreaks. In this study, we used molecular genotyping to investigate clustered cases of Fusarium solani species complex (FSSC) infection that occurred in eight Sphyrnidae sharks under managed care at a public aquarium. Genetic relationships between fungal strains were determined by multi-locus sequence typing (MLST) analysis based on DNA sequencing at five loci, followed by comparison with sequences of 50 epidemiologically unrelated FSSC strains. Our genotyping approach revealed that F. keratoplasticum and F. solani haplotype 9x were most commonly isolated. In one case, the infection proved to be with another Hypocrealian rare opportunistic pathogen Metarhizium robertsii. Twice, sharks proved to be infected with FSSC strains with the same MLST sequence type, supporting the hypothesis the hypothesis that common environmental populations of fungi existed for these sharks and would suggest the longtime persistence of the two clonal strains within the environment, perhaps in holding pools and life support systems of the aquarium. This study highlights how molecular tools like MLST can be used to investigate outbreaks of microbiological disease. This work reinforces the need for regular controls of water quality to reduce microbiological contamination due to waterborne microorganisms.

The (not so) Immortal Strand Hypothesis

OpenAIRE

Tomasetti, Cristian; Bozic, Ivana

2015-01-01

Background: Non-random segregation of DNA strands during stem cell replication has been proposed as a mechanism to minimize accumulated genetic errors in stem cells of rapidly dividing tissues. According to this hypothesis, an “immortal” DNA strand is passed to the stem cell daughter and not the more differentiated cell, keeping the stem cell lineage replication error-free. After it was introduced, experimental evidence both in favor and against the hypothesis has been presented. Principal...

Revisiting the Dutch hypothesis

NARCIS (Netherlands)

Postma, Dirkje S.; Weiss, Scott T.; van den Berge, Maarten; Kerstjens, Huib A. M.; Koppelman, Gerard H.

The Dutch hypothesis was first articulated in 1961, when many novel and advanced scientific techniques were not available, such as genomics techniques for pinpointing genes, gene expression, lipid and protein profiles, and the microbiome. In addition, computed tomographic scans and advanced analysis

Cancer Epidemiology Data Repository (CEDR)

Science.gov (United States)

In an effort to broaden access and facilitate efficient data sharing, the Epidemiology and Genomics Research Program (EGRP) has created the Cancer Epidemiology Data Repository (CEDR), a centralized, controlled-access database, where Investigators can deposit individual-level de-identified observational cancer datasets.

Erasing no-man's land by thermodynamically stabilizing the liquid-liquid transition in tetrahedral particles.

Science.gov (United States)

Smallenburg, Frank; Filion, Laura; Sciortino, Francesco

2014-09-01

One of the most controversial hypotheses for explaining the origin of the thermodynamic anomalies characterizing liquid water postulates the presence of a metastable second-order liquid-liquid critical point [1] located in the "no-man's land" [2]. In this scenario, two liquids with distinct local structure emerge near the critical temperature. Unfortunately, since spontaneous crystallization is rapid in this region, experimental support for this hypothesis relies on significant extrapolations, either from the metastable liquid or from amorphous solid water [3, 4]. Although the liquid-liquid transition is expected to feature in many tetrahedrally coordinated liquids, including silicon [5], carbon [6] and silica, even numerical studies of atomic and molecular models have been unable to conclusively prove the existence of this transition. Here we provide such evidence for a model in which it is possible to continuously tune the softness of the interparticle interaction and the flexibility of the bonds, the key ingredients controlling the existence of the critical point. We show that conditions exist where the full coexistence is thermodynamically stable with respect to crystallization. Our work offers a basis for designing colloidal analogues of water exhibiting liquid-liquid transitions in equilibrium, opening the way for experimental confirmation of the original hypothesis.

Ophthalmic epidemiology in Europe

DEFF Research Database (Denmark)

Delcourt, Cécile; Korobelnik, Jean-François; Buitendijk, Gabriëlle H S

2016-01-01

The European Eye Epidemiology (E3) consortium is a recently formed consortium of 29 groups from 12 European countries. It already comprises 21 population-based studies and 20 other studies (case-control, cases only, randomized trials), providing ophthalmological data on approximately 170,000 Euro......The European Eye Epidemiology (E3) consortium is a recently formed consortium of 29 groups from 12 European countries. It already comprises 21 population-based studies and 20 other studies (case-control, cases only, randomized trials), providing ophthalmological data on approximately 170......,000 European participants. The aim of the consortium is to promote and sustain collaboration and sharing of data and knowledge in the field of ophthalmic epidemiology in Europe, with particular focus on the harmonization of methods for future research, estimation and projection of frequency and impact...

How to make epidemiological training infectious.

Directory of Open Access Journals (Sweden)

Steve E Bellan

Full Text Available Modern infectious disease epidemiology builds on two independently developed fields: classical epidemiology and dynamical epidemiology. Over the past decade, integration of the two fields has increased in research practice, but training options within the fields remain distinct with few opportunities for integration in the classroom. The annual Clinic on the Meaningful Modeling of Epidemiological Data (MMED at the African Institute for Mathematical Sciences has begun to address this gap. MMED offers participants exposure to a broad range of concepts and techniques from both epidemiological traditions. During MMED 2010 we developed a pedagogical approach that bridges the traditional distinction between classical and dynamical epidemiology and can be used at multiple educational levels, from high school to graduate level courses. The approach is hands-on, consisting of a real-time simulation of a stochastic outbreak in course participants, including realistic data reporting, followed by a variety of mathematical and statistical analyses, stemming from both epidemiological traditions. During the exercise, dynamical epidemiologists developed empirical skills such as study design and learned concepts of bias while classical epidemiologists were trained in systems thinking and began to understand epidemics as dynamic nonlinear processes. We believe this type of integrated educational tool will prove extremely valuable in the training of future infectious disease epidemiologists. We also believe that such interdisciplinary training will be critical for local capacity building in analytical epidemiology as Africa continues to produce new cohorts of well-trained mathematicians, statisticians, and scientists. And because the lessons draw on skills and concepts from many fields in biology--from pathogen biology, evolutionary dynamics of host--pathogen interactions, and the ecology of infectious disease to bioinformatics, computational biology, and

Energy Exchange Dynamics across L-H transitions in NSTX

Science.gov (United States)

Diallo, Ahmed

2017-10-01

H-mode is planned for future devices such as ITER, and is preceded by a low (L) to high (H) transition. A key question remains. What is the mechanism behind the L-H transition? Most theoretical descriptions of the L-H transition are based on the shear of the radial electric field and coincident ExB poloidal flow shear, which is thought to be responsible for the onset of the anomalous transport suppression that leads to the L-H transition. This talk will focus on the analysis of the flow dynamics across the L-H transition in NSTX. We analyze the L-H transition dynamics using the velocimetry of 2D edge turbulence data from gas-puff imaging (GPI). We determine the velocity components at the edge across the L-H transition for 17 discharges with three types of heating power (NBI, ohmic, and RF). Using a reduced model equation of edge flows and turbulence, the energy transfer dynamics is compared with the turbulence depletion hypothesis of the predator-prey model. In order for Reynolds work to suppress the turbulence, it must deplete the total turbulent free energy, including the thermal free-energy term. For this to occur, the increase in kinetic energy in the mean flow over the L-H transition must be comparable to the pre-transition thermal free energy. However, this ratio was found to be of order 10-2. Although there are significant simplifications in the theoretical model, they are unlikely to cause inaccuracy by two orders of magnitude, suggesting that direct turbulence depletion by the Reynolds work may not be large enough to explain the L-H transition on NSTX, contrary to the predator-prey model. This work is supported by the US DOE Contract No. DE-AC02-09CH11466.

The evolving epidemiology of inflammatory bowel disease.

LENUS (Irish Health Repository)

Shanahan, Fergus

2009-07-01

Epidemiologic studies in inflammatory bowel disease (IBD) include assessments of disease burden and evolving patterns of disease presentation. Although it is hoped that sound epidemiologic studies provide aetiological clues, traditional risk factor-based epidemiology has provided limited insights into either Crohn\\'s disease or ulcerative colitis etiopathogenesis. In this update, we will summarize how the changing epidemiology of IBD associated with modernization can be reconciled with current concepts of disease mechanisms and will discuss studies of clinically significant comorbidity in IBD.

The linear hypothesis - an idea whose time has passed

International Nuclear Information System (INIS)

Tschaeche, A.N.

1995-01-01

The linear no-threshold hypothesis is the basis for radiation protection standards in the United States. In the words of the National Council on Radiation Protection and Measurements (NCRP), the hypothesis is: open-quotes In the interest of estimating effects in humans conservatively, it is not unreasonable to follow the assumption of a linear relationship between dose and effect in the low dose regions for which direct observational data are not available.close quotes The International Commission on Radiological Protection (ICRP) stated the hypothesis in a slightly different manner: open-quotes One such basic assumption ... is that ... there is ... a linear relationship without threshold between dose and the probability of an effect. The hypothesis was necessary 50 yr ago when it was first enunciated because the dose-effect curve for ionizing radiation for effects in humans was not known. The ICRP and NCRP needed a model to extrapolate high-dose effects to low-dose effects. So the linear no-threshold hypothesis was born. Certain details of the history of the development and use of the linear hypothesis are presented. In particular, use of the hypothesis by the U.S. regulatory agencies is examined. Over time, the sense of the hypothesis has been corrupted. The corruption of the hypothesis into the current paradigm of open-quote a little radiation, no matter how small, can and will harm youclose quotes is presented. The reasons the corruption occurred are proposed. The effects of the corruption are enumerated, specifically, the use of the corruption by the antinuclear forces in the United States and some of the huge costs to U.S. taxpayers due to the corruption. An alternative basis for radiation protection standards to assure public safety, based on the weight of scientific evidence on radiation health effects, is proposed

Multiple hypothesis tracking for the cyber domain

Science.gov (United States)

Schwoegler, Stefan; Blackman, Sam; Holsopple, Jared; Hirsch, Michael J.

2011-09-01

This paper discusses how methods used for conventional multiple hypothesis tracking (MHT) can be extended to domain-agnostic tracking of entities from non-kinematic constraints such as those imposed by cyber attacks in a potentially dense false alarm background. MHT is widely recognized as the premier method to avoid corrupting tracks with spurious data in the kinematic domain but it has not been extensively applied to other problem domains. The traditional approach is to tightly couple track maintenance (prediction, gating, filtering, probabilistic pruning, and target confirmation) with hypothesis management (clustering, incompatibility maintenance, hypothesis formation, and Nassociation pruning). However, by separating the domain specific track maintenance portion from the domain agnostic hypothesis management piece, we can begin to apply the wealth of knowledge gained from ground and air tracking solutions to the cyber (and other) domains. These realizations led to the creation of Raytheon's Multiple Hypothesis Extensible Tracking Architecture (MHETA). In this paper, we showcase MHETA for the cyber domain, plugging in a well established method, CUBRC's INFormation Engine for Real-time Decision making, (INFERD), for the association portion of the MHT. The result is a CyberMHT. We demonstrate the power of MHETA-INFERD using simulated data. Using metrics from both the tracking and cyber domains, we show that while no tracker is perfect, by applying MHETA-INFERD, advanced nonkinematic tracks can be captured in an automated way, perform better than non-MHT approaches, and decrease analyst response time to cyber threats.

Demography, maternal health and the epidemiology of malaria and other major infectious diseases in the rural department Tsamba-Magotsi, Ngounie Province, in central African Gabon

Directory of Open Access Journals (Sweden)

R. Zoleko Manego

2017-01-01

Full Text Available Abstract Background Sub-Saharan Africa is undergoing an epidemiological transition from a predominance of infectious diseases to non-communicable and lifestyle related conditions. However, the pace of this transition and the pattern of disease epidemiology are uneven between affluent urban and rural poor populations. To address this question for a remote rural region located in the central African rainforest region of Gabon, this study was conducted to assess reasons for health care attendance and to characterize the epidemiology of malaria and other major infectious diseases for the department of Tsamba Magotsi. Methods Major causes for health care attendance were collected from local hospital records. Cross sectional population based surveys were performed for the assessment of local malaria epidemiology. Pregnant women attending antenatal care services were surveyed as a sentinel population for the characterization of chronic viral and parasitic infections in the community. Results Infectious diseases were responsible for 71% (7469 of a total of 10,580 consultations at the formal health care sector in 2010. Overall, malaria – defined by clinical syndrome – remained the most frequent cause for health care attendance. A cross sectional malaria survey in 840 asymptomatic individuals residing in Tsamba Magotsi resulted in a Plasmodium spp. infection prevalence of 37%. The infection rate in 2–10 year old asymptomatic children – a standard measure for malaria endemicity – was 46% (100 of 217 with P. falciparum as predominant species (79%. Infection with other plasmodial species (P. ovale and P. malariae presented most commonly as coinfections (23.2%. Prevalence of HIV, HBV, and syphilis were 6.2, 7.3, and 2.5%, respectively, in cross-sectional assessments of antenatal care visits of pregnant women. Urogenital schistosomiasis and the filarial pathogens Loa loa and Mansonella perstans are highly prevalent chronic parasitic infections

Epidemiological methods: a brief review

International Nuclear Information System (INIS)

Winkelstein, W. Jr.

1983-01-01

Epidemiology, the study of disease distributions in populations and the factors which influence these distributions, is an observational science, i.e., its data base consists of measurements made on free living individuals characterized by presence or absence of disease states and putative risk factors. Epidemiological studies are usually classified as descriptive or analytical. Descriptive studies are primarily used for planning and evaluating health programs or to generate etiological hypotheses. Analytical studies are primarily used for testing etiological hypotheses. Analytical studies are designed either as cohort investigations in which populations with and without a putative risk factor are followed through time to ascertain their differential incidence of disease, or case-control investigations in which the history of exposure to a putative risk factor is compared among persons with a disease and appropriate controls free of disease. Both descriptive and analytical epidemiological studies have been applied to health physics problems. Examples of such problems and the epidemiological methods used to explore them will be presented

A reformulation of the hygiene hypothesis

DEFF Research Database (Denmark)

Hersoug, Lars-Georg

2006-01-01

Epidemiological studies have shown an inverse relationship between allergic respiratory diseases and the number of siblings. It was hypothesized that the lower prevalence of allergic respiratory diseases in large sibships was due to cross-infections between siblings. According to this hygiene...

The epidemiology of HIV among young people in sub-Saharan Africa: know your local epidemic and its implications for prevention.

Science.gov (United States)

Napierala Mavedzenge, Sue; Olson, Rick; Doyle, Aoife M; Changalucha, John; Ross, David A

2011-12-01

Broad patterns of HIV epidemiology are frequently used to design generic HIV programs in sub-Saharan Africa. We reviewed the epidemiology of HIV among young people in sub-Saharan Africa, and explored the unique dynamics of infection in its different regions. In 2009, HIV prevalence among youth in sub-Saharan Africa was an estimated 1.4% in males and 3.4% in females, but these values mask wide variation at regional and national levels. Within countries there are further major differences in HIV prevalence, such as by sex, urban/rural location, economic status, education, or ethnic group. Within this highly nuanced context, HIV prevention programs targeting youth must consider both where new infections are occurring and where they are coming from. Given the epidemiology, one-size-fits-all HIV prevention programs are usually inappropriate at regional and national levels. Consideration of local context and risk associated with life transitions, such as leaving school or getting married, is imperative to successful programming for young people. Copyright © 2011 Society for Adolescent Health and Medicine. Published by Elsevier Inc. All rights reserved.

Universality hypothesis breakdown at one-loop order

Science.gov (United States)

Carvalho, P. R. S.

2018-05-01

We probe the universality hypothesis by analytically computing the at least two-loop corrections to the critical exponents for q -deformed O (N ) self-interacting λ ϕ4 scalar field theories through six distinct and independent field-theoretic renormalization group methods and ɛ -expansion techniques. We show that the effect of q deformation on the one-loop corrections to the q -deformed critical exponents is null, so the universality hypothesis is broken down at this loop order. Such an effect emerges only at the two-loop and higher levels, and the validity of the universality hypothesis is restored. The q -deformed critical exponents obtained through the six methods are the same and, furthermore, reduce to their nondeformed values in the appropriated limit.

The Kibble-Zurek mechanism in phase transitions of non-equilibrium systems

Science.gov (United States)

Cheung, Hil F. H.; Patil, Yogesh S.; Date, Aditya G.; Vengalattore, Mukund

2017-04-01

We experimentally realize a driven-dissipative phase transition using a mechanical parametric amplifier to demonstrate key signatures of a second order phase transition, including a point where the susceptibilities and relaxation time scales diverge, and where the system exhibits a spontaneous breaking of symmetry. Though reminiscent of conventional equilibrium phase transitions, it is unclear if such driven-dissipative phase transitions are amenable to the conventional Landau-Ginsburg-Wilson paradigm, which relies on concepts of scale invariance and universality, and recent work has shown that such phase transitions can indeed lie beyond such conventional universality classes. By quenching the system past the critical point, we investigate the dynamics of the emergent ordered phase and find that our measurements are in excellent agreement with the Kibble-Zurek mechanism. In addition to verifying the Kibble-Zurek hypothesis in driven-dissipative phase transitions for the first time, we also demonstrate that the measured critical exponents accurately reflect the interplay between intrinsic coherent dynamics and environmental correlations, showing a clear departure from mean field exponents in the case of non-Markovian system-bath interactions. We further discuss how reservoir engineering and the imposition of artificial environmental correlations can result in the stabilization of novel many-body quantum phases and aid in the creation of exotic non-equilibrium states of matter.

Null but not void: considerations for hypothesis testing.

Science.gov (United States)

Shaw, Pamela A; Proschan, Michael A

2013-01-30

Standard statistical theory teaches us that once the null and alternative hypotheses have been defined for a parameter, the choice of the statistical test is clear. Standard theory does not teach us how to choose the null or alternative hypothesis appropriate to the scientific question of interest. Neither does it tell us that in some cases, depending on which alternatives are realistic, we may want to define our null hypothesis differently. Problems in statistical practice are frequently not as pristinely summarized as the classic theory in our textbooks. In this article, we present examples in statistical hypothesis testing in which seemingly simple choices are in fact rich with nuance that, when given full consideration, make the choice of the right hypothesis test much less straightforward. Published 2012. This article is a US Government work and is in the public domain in the USA.

Meteorological and intelligence evidence of long-distance transit of chemical weapons fallout from bombing early in the 1991 Persian Gulf War.

Science.gov (United States)

Tuite, James J; Haley, Robert W

2013-01-01

Coalition bombings on the night of 18-19 January 1991, early in the Gulf War, targeted the Iraqi chemical weapons infrastructure. On 19 January 1991, nerve agent alarms sounded within Coalition positions hundreds of kilometers to the south, and the trace presence of sarin vapor was identified by multiple technologies. Considering only surface dispersion of plumes from explosions, officials concluded that the absence of casualties around bombed sites precluded long-distance transit of debris to US troop positions to explain the alarms and detections. Consequently, they were discounted as false positives, and low-level nerve agent exposure early in the air war was disregarded in epidemiologic investigations of chronic illnesses. Newly assembled evidence indicates that plumes from those nighttime bombings of Iraqi chemical facilities would have traversed the stable nocturnal boundary layer and penetrated the residual layer where they would be susceptible to rapid transit by supergeostrophic winds. This explanation is supported by plume height predictions, available weather charts, weather satellite images showing transit of a hot air mass, effects of solar mixing of atmospheric layers, and observations of a stationary weather front and thermal inversion in the region. Current evidence supports long-distance transit. Epidemiologic studies of chronic postwar illness should be reassessed using veterans' reports of hearing nerve agent alarms as the measure of exposure. Copyright © 2012 S. Karger AG, Basel.

Questioning the social intelligence hypothesis.

Science.gov (United States)

Holekamp, Kay E

2007-02-01

The social intelligence hypothesis posits that complex cognition and enlarged "executive brains" evolved in response to challenges that are associated with social complexity. This hypothesis has been well supported, but some recent data are inconsistent with its predictions. It is becoming increasingly clear that multiple selective agents, and non-selective constraints, must have acted to shape cognitive abilities in humans and other animals. The task now is to develop a larger theoretical framework that takes into account both inter-specific differences and similarities in cognition. This new framework should facilitate consideration of how selection pressures that are associated with sociality interact with those that are imposed by non-social forms of environmental complexity, and how both types of functional demands interact with phylogenetic and developmental constraints.

The Younger Dryas impact hypothesis: A critical review

NARCIS (Netherlands)

van Hoesel, A.; Hoek, W.Z.; Pennock, G.M.; Drury, Martyn

2014-01-01

The Younger Dryas impact hypothesis suggests that multiple extraterrestrial airbursts or impacts resulted in the Younger Dryas cooling, extensive wildfires, megafaunal extinctions and changes in human population. After the hypothesis was first published in 2007, it gained much criticism, as the

Radiation carcinogenesis: Epidemiology and biological significance

International Nuclear Information System (INIS)

Boice, J.D.; Fraumeni, J.F.

1984-01-01

Epidemiologic studies of populations exposed to radiation have led to the identification of a preventable cause of cancer, but in the long run perhaps the most important contribution of radiation studies will be to provide insights into the basic processes of human carcinogenesis. In this volume, key investigators of major epidemiologic projects summarize their observations to date, including information to help assess the effects of low-level exposures. Experimentalists and theorists emphasize the relevance of laboratory and epidemiologic data in elucidating carcinogenic risks and mechanisms in man. This volume was prepared with several objectives in mind: (a) organize and synthesize knowledge on radiation carcinogenesis through epidemiologic and experimental approaches; (b) illustrate and explore ways of utilizing this information to gain insights into the fundamental mechanisms of cancer development; (c) stimulate the formation of hypotheses suited to experimental or epidemiologic testing, theoretical modeling, and multidisciplinary approaches; and (d) identify recent advances that clarify dose-response relationships and the influence of low-dose exposures, provide leads to carcinogenic mechanisms and host-environmental interactions, and suggest strategies for future research and preventive action

A Dopamine Hypothesis of Autism Spectrum Disorder.

Science.gov (United States)

Pavăl, Denis

2017-01-01

Autism spectrum disorder (ASD) comprises a group of neurodevelopmental disorders characterized by social deficits and stereotyped behaviors. While several theories have emerged, the pathogenesis of ASD remains unknown. Although studies report dopamine signaling abnormalities in autistic patients, a coherent dopamine hypothesis which could link neurobiology to behavior in ASD is currently lacking. In this paper, we present such a hypothesis by proposing that autistic behavior arises from dysfunctions in the midbrain dopaminergic system. We hypothesize that a dysfunction of the mesocorticolimbic circuit leads to social deficits, while a dysfunction of the nigrostriatal circuit leads to stereotyped behaviors. Furthermore, we discuss 2 key predictions of our hypothesis, with emphasis on clinical and therapeutic aspects. First, we argue that dopaminergic dysfunctions in the same circuits should associate with autistic-like behavior in nonautistic subjects. Concerning this, we discuss the case of PANDAS (pediatric autoimmune neuropsychiatric disorder associated with streptococcal infections) which displays behaviors similar to those of ASD, presumed to arise from dopaminergic dysfunctions. Second, we argue that providing dopamine modulators to autistic subjects should lead to a behavioral improvement. Regarding this, we present clinical studies of dopamine antagonists which seem to have improving effects on autistic behavior. Furthermore, we explore the means of testing our hypothesis by using neuroreceptor imaging, which could provide comprehensive evidence for dopamine signaling dysfunctions in autistic subjects. Lastly, we discuss the limitations of our hypothesis. Along these lines, we aim to provide a dopaminergic model of ASD which might lead to a better understanding of the ASD pathogenesis. © 2017 S. Karger AG, Basel.

El abordaje epidemiológico de las desigualdades en salud a nivel local The epidemiological approach to health inequalities at the local level

Directory of Open Access Journals (Sweden)

Marcio Alazraqui

2007-02-01

Full Text Available Para responder la pregunta ¿cuáles son los usos y limitaciones de la epidemiología en la reducción de las desigualdades en el nivel local? se problematiza el "papel" de la epidemiología. La hipótesis es que la epidemiología produce conocimiento útil a la gestión en el nivel local para el desarrollo de intervenciones dirigidas a la reducción de desigualdades en salud. Estas desigualdades se expresan en un espacio construido por colectivos humanos en procesos sociales e históricos. La producción de conocimiento epidemiológico en el nivel local debe estar orientada a dar soporte a las acciones de un actor social en situación y en un determinado escenario. Por eso se revalorizan los estudios ecológicos y la georreferencia. Esta producción y aplicación de conocimiento es también un fenómeno organizacional. Se entienden las organizaciones como "redes de conversaciones". Se concluye que las acciones estratégicas y las acciones comunicativas de los trabajadores de salud deben constituirse como eje central en la definición de nuevos modelos de cuidado y de gestión comprometidos con la reducción de desigualdades en salud, donde la epidemiología cumple un rol relevante.What are the advantages and limitations of epidemiology for decreasing health inequalities at the local level? To answer this question, the current article discusses the role of epidemiology. The hypothesis is that epidemiology produces useful knowledge for local management of interventions aimed at reducing health inequalities, expressed in spaces built by human communities through social and historical processes. Local production of epidemiological knowledge should support action by social actors in specific situations and contexts, thus renewing the appreciation for ecological designs and georeference studies. Such knowledge output and application are also an organizational phenomenon. Organizations can be seen as "conversational networks". In conclusion, strategic

Testing competing forms of the Milankovitch hypothesis

DEFF Research Database (Denmark)

Kaufmann, Robert K.; Juselius, Katarina

2016-01-01

We test competing forms of the Milankovitch hypothesis by estimating the coefficients and diagnostic statistics for a cointegrated vector autoregressive model that includes 10 climate variables and four exogenous variables for solar insolation. The estimates are consistent with the physical...... ice volume and solar insolation. The estimated adjustment dynamics show that solar insolation affects an array of climate variables other than ice volume, each at a unique rate. This implies that previous efforts to test the strong form of the Milankovitch hypothesis by examining the relationship...... that the latter is consistent with a weak form of the Milankovitch hypothesis and that it should be restated as follows: Internal climate dynamics impose perturbations on glacial cycles that are driven by solar insolation. Our results show that these perturbations are likely caused by slow adjustment between land...

The science of epidemiology and the methods needed for public health assessments: a review of epidemiology textbooks.

Science.gov (United States)

Gouda, Hebe N; Powles, John W

2014-02-10

Epidemiology is often described as 'the science of public health'. Here we aim to assess the extent that epidemiological methods, as covered in contemporary standard textbooks, provide tools that can assess the relative magnitude of public health problems and can be used to help rank and assess public health priorities. Narrative literature review. Thirty textbooks were grouped into three categories; pure, extended or applied epidemiology, were reviewed with attention to the ways the discipline is characterised and the nature of the analytical methods described. Pure texts tend to present a strict hierarchy of methods with those metrics deemed to best serve aetiological inquiry at the top. Extended and applied texts employ broader definitions of epidemiology but in most cases, the metrics described are also those used in aetiological inquiry and may not be optimal for capturing the consequences and social importance of injuries and disease onsets. The primary scientific purpose of epidemiology, even amongst 'applied' textbooks, is aetiological inquiry. Authors do not readily extend to methods suitable for assessing public health problems and priorities.

Dynamical agents' strategies and the fractal market hypothesis

Czech Academy of Sciences Publication Activity Database

Vácha, Lukáš; Vošvrda, Miloslav

2005-01-01

Roč. 14, č. 2 (2005), s. 172-179 ISSN 1210-0455 Grant - others:GA UK(CZ) 454/2004/A EK/FSV Institutional research plan: CEZ:AV0Z10750506 Keywords : efficient market hypothesis * fractal market hypothesis * agent's investment horizons Subject RIV: AH - Economics

Investigating the environmental Kuznets curve hypothesis in Vietnam

International Nuclear Information System (INIS)

Al-Mulali, Usama; Saboori, Behnaz; Ozturk, Ilhan

2015-01-01

This study investigates the existence of the environmental Kuznets curve (EKC) hypothesis in Vietnam during the period 1981–2011. To realize the goals of this study, a pollution model was established applying the Autoregressive Distributed Lag (ARDL) methodology. The results revealed that the pollution haven hypothesis does exist in Vietnam because capital increases pollution. In addition, imports also increase pollution which indicates that most of Vietnam's imported products are energy intensive and highly polluted. However, exports have no effect on pollution which indicates that the level of exports is not significant enough to affect pollution. Moreover, fossil fuel energy consumption increases pollution while renewable energy consumption has no significant effect in reducing pollution. Furthermore, labor force reduces pollution since most of Vietnam's labor force is in the agricultural and services sectors which are less energy intensive than the industrial sector. Based on the obtained results, the EKC hypothesis does not exist because the relationship between GDP and pollution is positive in both the short and long run. - Highlights: • The environmental Kuznets curve (EKC) hypothesis in Vietnam is investigated. • The Autoregressive Distributed Lag (ARDL) methodology was utilized. • The EKC hypothesis does not exist

Social learning and evolution: the cultural intelligence hypothesis

Science.gov (United States)

van Schaik, Carel P.; Burkart, Judith M.

2011-01-01

If social learning is more efficient than independent individual exploration, animals should learn vital cultural skills exclusively, and routine skills faster, through social learning, provided they actually use social learning preferentially. Animals with opportunities for social learning indeed do so. Moreover, more frequent opportunities for social learning should boost an individual's repertoire of learned skills. This prediction is confirmed by comparisons among wild great ape populations and by social deprivation and enculturation experiments. These findings shaped the cultural intelligence hypothesis, which complements the traditional benefit hypotheses for the evolution of intelligence by specifying the conditions in which these benefits can be reaped. The evolutionary version of the hypothesis argues that species with frequent opportunities for social learning should more readily respond to selection for a greater number of learned skills. Because improved social learning also improves asocial learning, the hypothesis predicts a positive interspecific correlation between social-learning performance and individual learning ability. Variation among primates supports this prediction. The hypothesis also predicts that more heavily cultural species should be more intelligent. Preliminary tests involving birds and mammals support this prediction too. The cultural intelligence hypothesis can also account for the unusual cognitive abilities of humans, as well as our unique mechanisms of skill transfer. PMID:21357223

Social learning and evolution: the cultural intelligence hypothesis.

Science.gov (United States)

van Schaik, Carel P; Burkart, Judith M

2011-04-12

If social learning is more efficient than independent individual exploration, animals should learn vital cultural skills exclusively, and routine skills faster, through social learning, provided they actually use social learning preferentially. Animals with opportunities for social learning indeed do so. Moreover, more frequent opportunities for social learning should boost an individual's repertoire of learned skills. This prediction is confirmed by comparisons among wild great ape populations and by social deprivation and enculturation experiments. These findings shaped the cultural intelligence hypothesis, which complements the traditional benefit hypotheses for the evolution of intelligence by specifying the conditions in which these benefits can be reaped. The evolutionary version of the hypothesis argues that species with frequent opportunities for social learning should more readily respond to selection for a greater number of learned skills. Because improved social learning also improves asocial learning, the hypothesis predicts a positive interspecific correlation between social-learning performance and individual learning ability. Variation among primates supports this prediction. The hypothesis also predicts that more heavily cultural species should be more intelligent. Preliminary tests involving birds and mammals support this prediction too. The cultural intelligence hypothesis can also account for the unusual cognitive abilities of humans, as well as our unique mechanisms of skill transfer.

Personal Hypothesis Testing: The Role of Consistency and Self-Schema.

Science.gov (United States)

Strohmer, Douglas C.; And Others

1988-01-01

Studied how individuals test hypotheses about themselves. Examined extent to which Snyder's bias toward confirmation persists when negative or nonconsistent personal hypothesis is tested. Found negativity or positivity did not affect hypothesis testing directly, though hypothesis consistency did. Found cognitive schematic variable (vulnerability…

Mitochondrial DNA and Cancer Epidemiology Workshop

Science.gov (United States)

A workshop to review the state-of-the science in the mitochondrial DNA field and its use in cancer epidemiology, and to develop a concept for a research initiative on mitochondrial DNA and cancer epidemiology.

Radiation epidemiology: Past and present

International Nuclear Information System (INIS)

Boice, J.D. Jr.

1997-01-01

Major advancements in radiation epidemiology have occurred during the last several years in studies of atomic bomb survivors, patients given medical radiation, and radiation workers, including underground miners. Risks associated with the Chernobyl accident, indoor radon and childhood exposure to I-131 have yet to be elucidated. Situations in the former Soviet Union around Chelyabinsk, a nuclear installation in the southern Urals, and in the Altai, which received radioactive fallout from weapons testing at Semipalatinsk, Kazakhstan, have the potential to provide information on the effects of chronic radiation exposure. Since Roentgen's discovery of x-rays just 100 years ago, a tremendous amount of knowledge has been accumulated about human health effects following irradiation. The 1994 UNSCEAR report contains the latest compilation and synthesis of radiation epidemiology. This overview will cover epidemiology from a radiation perspective. The different types of study methodologies will be described, followed by a kaleidoscope coverage of past and present studies; ending with some remaining questions in radiation epidemiology. This should set the stage for future chapters, and stimulate thinking about implications of the new data on radiation cancer risks

Evaluating the Stage Learning Hypothesis.

Science.gov (United States)

Thomas, Hoben

1980-01-01

A procedure for evaluating the Genevan stage learning hypothesis is illustrated by analyzing Inhelder, Sinclair, and Bovet's guided learning experiments (in "Learning and the Development of Cognition." Cambridge: Harvard University Press, 1974). (Author/MP)

Multi-agent sequential hypothesis testing

KAUST Repository

Kim, Kwang-Ki K.

2014-12-15

This paper considers multi-agent sequential hypothesis testing and presents a framework for strategic learning in sequential games with explicit consideration of both temporal and spatial coordination. The associated Bayes risk functions explicitly incorporate costs of taking private/public measurements, costs of time-difference and disagreement in actions of agents, and costs of false declaration/choices in the sequential hypothesis testing. The corresponding sequential decision processes have well-defined value functions with respect to (a) the belief states for the case of conditional independent private noisy measurements that are also assumed to be independent identically distributed over time, and (b) the information states for the case of correlated private noisy measurements. A sequential investment game of strategic coordination and delay is also discussed as an application of the proposed strategic learning rules.

BANKS IN TRANSITION COUNTRIES AS ONE OF MOST ATTRACTIVE INVESTMENTS

Directory of Open Access Journals (Sweden)

Lidija Dedi

2011-06-01

Full Text Available The primary goal of this paper is to analyze the banking sector in transition countries in Central and Eastern Europe, and identify bank’s potential as an investment in the globalized environment. The primary hypothesis is that banking sector is one of the most attractive investment areas in transition countries. In the comparison with financial systems of G7 and other growth countries, the financial industry in transition countries shows significant potential for future growth and development. Operating as universal bank with acquired position in financial supervisory bodies banks can easy control and slows down growth and development of nonbanking financial institutions. They are not overly involved in risky operations of securitization and were not so much exposed to the recent crisis. Analysis of the banking sector in transition countries has been made on available sources of secondary data and comparable quantities. Comparable quantities are analyzed with descriptive statistics, starting from the general characteristics of the region and individual countries, through macroeconomic indicator analysis to analysis of assorted indicators of banking sector which have dominant influence on prospective cash flows and risk, i.e key components of bank’s value as an investment.

A default Bayesian hypothesis test for ANOVA designs

NARCIS (Netherlands)

Wetzels, R.; Grasman, R.P.P.P.; Wagenmakers, E.J.

2012-01-01

This article presents a Bayesian hypothesis test for analysis of variance (ANOVA) designs. The test is an application of standard Bayesian methods for variable selection in regression models. We illustrate the effect of various g-priors on the ANOVA hypothesis test. The Bayesian test for ANOVA

Transition questions in clinical practice - validity and reproducibility

DEFF Research Database (Denmark)

Lauridsen, Henrik Hein

2008-01-01

Transition questions in CLINICAL practice - validity and reproducibility Lauridsen HH1, Manniche C3, Grunnet-Nilsson N1, Hartvigsen J1,2 1   Clinical Locomotion Science, Institute of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark. e-mail: hlauridsen......@health.sdu.dk 2   Nordic Institute of Chiropractic and Clinical Biomechanics, Part of Clinical Locomotion Science, Odense, Denmark 3   Backcenter Funen, Part of Clinical Locomotion Science, Ringe, Denmark   Abstract  Understanding a change score is indispensable for interpretation of results from clinical studies...... are reproducible in patients with low back pain and/or leg pain. Despite critique of several biases, our results have reinforced the construct validity of TQ’s as an outcome measure since only 1 hypothesis was rejected. On the basis of our findings we have outlined a proposal for a standardised use of transition...

Physiological constrains on Sverdrup's Critical-Depth-Hypothesis: the influences of dark respiration and sinking

DEFF Research Database (Denmark)

Lindemann, Christian; Backhaus, Jan O.; St. John, Michael

2015-01-01

of the spring bloom. However, they neglect the cells ability to modify vital rates in response to changes in the external environment. In this study, we use a non-hydrostatic convection model coupled to an Individual-Based-Model to simulate changes phytoplankton cells during the transition from winter...... conditions as driven by convective mixing, and the onset of thermal stratification resulting in the spring bloom. The comparison between a simulation using a standard fixed rate approach in line with the original Sverdrup hypothesis and a simulation parameterized to include variable respiration and sinking...... replicate field observations when employing unrealistic parameter values. These results highlight the necessity to consider not only the physical and biological external controls determining phytoplankton dynamics but also the cells ability to modify critical physiological rates in response to external...

Translational Epidemiology in Psychiatry

Science.gov (United States)

Weissman, Myrna M.; Brown, Alan S.; Talati, Ardesheer

2012-01-01

Translational research generally refers to the application of knowledge generated by advances in basic sciences research translated into new approaches for diagnosis, prevention, and treatment of disease. This direction is called bench-to-bedside. Psychiatry has similarly emphasized the basic sciences as the starting point of translational research. This article introduces the term translational epidemiology for psychiatry research as a bidirectional concept in which the knowledge generated from the bedside or the population can also be translated to the benches of laboratory science. Epidemiologic studies are primarily observational but can generate representative samples, novel designs, and hypotheses that can be translated into more tractable experimental approaches in the clinical and basic sciences. This bedside-to-bench concept has not been explicated in psychiatry, although there are an increasing number of examples in the research literature. This article describes selected epidemiologic designs, providing examples and opportunities for translational research from community surveys and prospective, birth cohort, and family-based designs. Rapid developments in informatics, emphases on large sample collection for genetic and biomarker studies, and interest in personalized medicine—which requires information on relative and absolute risk factors—make this topic timely. The approach described has implications for providing fresh metaphors to communicate complex issues in interdisciplinary collaborations and for training in epidemiology and other sciences in psychiatry. PMID:21646577

Multi-agent sequential hypothesis testing

KAUST Repository

Kim, Kwang-Ki K.; Shamma, Jeff S.

2014-01-01

incorporate costs of taking private/public measurements, costs of time-difference and disagreement in actions of agents, and costs of false declaration/choices in the sequential hypothesis testing. The corresponding sequential decision processes have well

Maritim epidemiologi på Supercourse

DEFF Research Database (Denmark)

Jensen, Olaf

2015-01-01

Maritim epidemiologi er nu kommet med i samlingen af undervisningsmidler på ”Supercourse”. Der er oprettet en særlig mappe med Maritime Epidemiology og alle der har gode bidrag inden for området opfordres hermed til at publicere her. Supercourse er en samling af foredrag beregnet til at være en r...

Bayesian Hypothesis Testing

Energy Technology Data Exchange (ETDEWEB)

Andrews, Stephen A. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Sigeti, David E. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2017-11-15

These are a set of slides about Bayesian hypothesis testing, where many hypotheses are tested. The conclusions are the following: The value of the Bayes factor obtained when using the median of the posterior marginal is almost the minimum value of the Bayes factor. The value of τ² which minimizes the Bayes factor is a reasonable choice for this parameter. This allows a likelihood ratio to be computed with is the least favorable to H₀.

Snippets from the past: the evolution of Wade Hampton Frost's epidemiology as viewed from the American Journal of Hygiene/Epidemiology.

Science.gov (United States)

Morabia, Alfredo

2013-10-01

Wade Hampton Frost, who was a Professor of Epidemiology at Johns Hopkins University from 1919 to 1938, spurred the development of epidemiologic methods. His 6 publications in the American Journal of Hygiene, which later became the American Journal of Epidemiology, comprise a 1928 Cutter lecture on a theory of epidemics, a survey-based study of tonsillectomy and immunity to Corynebacterium diphtheriae (1931), 2 papers from a longitudinal study of the incidence of minor respiratory diseases (1933 and 1935), an attack rate ratio analysis of the decline of diphtheria in Baltimore (1936), and a 1936 lecture on the age, time, and cohort analysis of tuberculosis mortality. These 6 American Journal of Hygiene /American Journal of Epidemiology papers attest that Frost's personal evolution mirrored that of the emerging "early" epidemiology: The scope of epidemiology extended beyond the study of epidemics of acute infectious diseases, and rigorous comparative study designs and their associated quantitative methods came to light.

The Training of Epidemiologists and Diversity in Epidemiology: Findings from the 2006 Congress of Epidemiology Survey

Science.gov (United States)

Carter-Pokras, Olivia D.; Spirtas, Robert; Bethune, Lisa; Mays, Vickie; Freeman, Vincent L.; Cozier, Yvette C.

2013-01-01

Purpose In the past decade, we have witnessed increasing numbers of individuals entering the field of epidemiology. With the increase also has come a diversity of training and paths by which individuals entered the field. The purpose of this survey was characterization of the epidemiology workforce, its job diversity, and continuing education needs. Methods The Minority Affairs and Membership committees of the American College of Epidemiology (ACE) prepared and administered a workforce survey to identify racial/ethnic diversity, demographic background, workplace type, credentials, income, subspecialties, and continuing education needs of epidemiologists. The survey was self-administered to attendees of the Second North American Congress of Epidemiology in June 2006. Results A sample of 397 respondents of the 1348 registered for the Congress was captured (29.5% response). Epidemiologists who participated were from 36 states and 18 countries; 54.6% were trained at the doctoral level; 19.1% earned $120,001 or more a year. A wide range of epidemiology subspecialties and continuing education needs were identified. Conclusions This preliminary snapshot of epidemiologists indicates a wide range of training mechanisms, workplace sites, and subspecialties. Results indicate a need for examination of the core graduate training needs of epidemiologist as well as responding to desired professional development needs through the provision of continuing educations efforts. PMID:19344867

New Hypothesis for SOFC Ceramic Oxygen Electrode Mechanisms

DEFF Research Database (Denmark)

Mogensen, Mogens Bjerg; Chatzichristodoulou, Christodoulos; Graves, Christopher R.

2016-01-01

A new hypothesis for the electrochemical reaction mechanism in solid oxide cell ceramic oxygen electrodes is proposed based on literature including our own results. The hypothesis postulates that the observed thin layers of SrO-La2O3 on top of ceramic perovskite and other Ruddlesden-Popper...

The Purchasing Power Parity Hypothesis:

African Journals Online (AJOL)

2011-10-02

Oct 2, 2011 ... reject the unit root hypothesis in real exchange rates may simply be due to the shortness ..... Violations of Purchasing Power Parity and Their Implications for Efficient ... Official Intervention in the Foreign Exchange Market:.

Nutritional Transition: A Reviewo of Students' Eating Habits

Directory of Open Access Journals (Sweden)

Aline Juliana Ricardo

2012-12-01

Full Text Available The nutritional transition process has started in Brazil since the modifications of the standard Brazilian food also concomitant with changes in the epidemiological scenario, resulting in a decline of malnutrition, but in a significant increase in obesity in children and adolescents in all socioeconomic classes. The school age comprises the age group between seven and ten years old and is characterized as a period of growth with high nutritional requirements that must be supplied with quality food and in sufficient quantity to prevent future health problems. For this reason, school, teachers and family members should be responsible for the feeding habits of these children, through nutrition education projects, activities related to good nutrition and consistent information according to the real world of children. The aim of this paper is to describe some aspects of the food profile of students and its influence over the increasing incidence and prevalence of obesity and associated to co-morbidities, as well as to identify the transition process that the country has been experiencing.

Association between exposure to noise and risk of hypertension: a meta-analysis of observational epidemiological studies.

Science.gov (United States)

Fu, Wenning; Wang, Chao; Zou, Li; Liu, Qiaoyan; Gan, Yong; Yan, Shijiao; Song, Fujian; Wang, Zhihong; Lu, Zuxun; Cao, Shiyi

2017-12-01

An increasing amount of original studies suggested that exposure to noise could be associated with the risk of hypertension, but the results remain inconsistent and inconclusive. We aimed to synthesize available epidemiological evidence about the relationship between various types of noise and hypertension, and to explore the potential dose-response relationship between them in an up-to-date meta-analysis. We conducted a literature search of PubMed and Embase from these databases' inception through December 2016 to identify observational epidemiological studies examining the association between noise and risk of hypertension. A random effects model was used to combine the results of included studies. Dose-response meta-analysis was conducted to examine the potential dose-response relationship. In total, 32 studies (five cohort studies, one case-control study, and 26 cross-section studies) involving 264 678 participants were eligible for inclusion. Pooled result showed that living or working in environment with noise exposure was significantly associated with increased risk of hypertension (odds ratio 1.62; 95% confidence interval: 1.40-1.88). We found no evidence of a curve linear association between noise and risk of hypertension. A dose-response analysis suggested that, for an increment of per 10 dB(A) of noise, the combined odds ratio of hypertension was 1.06 (95% confidence interval: 1.04-1.08). Integrated epidemiological evidence supports the hypothesis that exposure to noise may be a risk factor of hypertension, and there is a positive dose-response association between them.

Adaptation hypothesis of biological efficiency of ionizing radiation

International Nuclear Information System (INIS)

Kudritskij, Yu.K.; Georgievskij, A.B.; Karpov, V.I.

1992-01-01

Adaptation hypothesis of biological efficiency of ionizing radiation is based on acknowledgement of invariance of fundamental laws and principles of biology related to unity of biota and media, evolution and adaptation for radiobiology. The basic arguments for adaptation hypothesis validity, its correspondence to the requirements imposed on scientific hypothes are presented

Transition-transversion bias is not universal: a counter example from grasshopper pseudogenes.

Directory of Open Access Journals (Sweden)

Irene Keller

2007-02-01

Full Text Available Comparisons of the DNA sequences of metazoa show an excess of transitional over transversional substitutions. Part of this bias is due to the relatively high rate of mutation of methylated cytosines to thymine. Postmutation processes also introduce a bias, particularly selection for codon-usage bias in coding regions. It is generally assumed, however, that there is a universal bias in favour of transitions over transversions, possibly as a result of the underlying chemistry of mutation. Surprisingly, this underlying trend has been evaluated only in two types of metazoan, namely Drosophila and the Mammalia. Here, we investigate a third group, and find no such bias. We characterize the point substitution spectrum in Podisma pedestris, a grasshopper species with a very large genome. The accumulation of mutations was surveyed in two pseudogene families, nuclear mitochondrial and ribosomal DNA sequences. The cytosine-guanine (CpG dinucleotides exhibit the high transition frequencies expected of methylated sites. The transition rate at other cytosine residues is significantly lower. After accounting for this methylation effect, there is no significant difference between transition and transversion rates. These results contrast with reports from other taxa and lead us to reject the hypothesis of a universal transition/transversion bias. Instead we suggest fundamental interspecific differences in point substitution processes.

New methods of testing nonlinear hypothesis using iterative NLLS estimator

Science.gov (United States)

Mahaboob, B.; Venkateswarlu, B.; Mokeshrayalu, G.; Balasiddamuni, P.

2017-11-01

This research paper discusses the method of testing nonlinear hypothesis using iterative Nonlinear Least Squares (NLLS) estimator. Takeshi Amemiya [1] explained this method. However in the present research paper, a modified Wald test statistic due to Engle, Robert [6] is proposed to test the nonlinear hypothesis using iterative NLLS estimator. An alternative method for testing nonlinear hypothesis using iterative NLLS estimator based on nonlinear hypothesis using iterative NLLS estimator based on nonlinear studentized residuals has been proposed. In this research article an innovative method of testing nonlinear hypothesis using iterative restricted NLLS estimator is derived. Pesaran and Deaton [10] explained the methods of testing nonlinear hypothesis. This paper uses asymptotic properties of nonlinear least squares estimator proposed by Jenrich [8]. The main purpose of this paper is to provide very innovative methods of testing nonlinear hypothesis using iterative NLLS estimator, iterative NLLS estimator based on nonlinear studentized residuals and iterative restricted NLLS estimator. Eakambaram et al. [12] discussed least absolute deviation estimations versus nonlinear regression model with heteroscedastic errors and also they studied the problem of heteroscedasticity with reference to nonlinear regression models with suitable illustration. William Grene [13] examined the interaction effect in nonlinear models disused by Ai and Norton [14] and suggested ways to examine the effects that do not involve statistical testing. Peter [15] provided guidelines for identifying composite hypothesis and addressing the probability of false rejection for multiple hypotheses.

Evidence for Mikheyev-Smirnov-Wolfenstein effects in solar neutrino flavor transitions

OpenAIRE

G. L. FogliU. of Bari and INFN, Bari; E. Lisi(U. of Bari and INFN, Bari); A. Marrone(U. of Bari and INFN, Bari); A Palazzo(U. of Bari and INFN, Bari)

2015-01-01

We point out that the recent data from the Sudbury Neutrino Observatory, together with other relevant measurements from solar and reactor neutrino experiments, convincingly show that the flavor transitions of solar neutrinos are affected by Mikheyev-Smirnov-Wolfenstein (MSW) effects. More precisely, one can safely reject the null hypothesis of no MSW interaction energy in matter, despite the fact that the interaction amplitude (formally treated as a free parameter) is still weakly constrained...

Modelling conditional correlations of asset returns: A smooth transition approach

DEFF Research Database (Denmark)

Silvennoinen, Annastiina; Teräsvirta, Timo

In this paper we propose a new multivariate GARCH model with time-varying conditional correlation structure. The time-varying conditional correlations change smoothly between two extreme states of constant correlations according to a predetermined or exogenous transition variable. An LM-test is d......In this paper we propose a new multivariate GARCH model with time-varying conditional correlation structure. The time-varying conditional correlations change smoothly between two extreme states of constant correlations according to a predetermined or exogenous transition variable. An LM......-test is derived to test the constancy of correlations and LM- and Wald tests to test the hypothesis of partially constant correlations. Analytical expressions for the test statistics and the required derivatives are provided to make computations feasible. An empirical example based on daily return series of ve...

A large scale test of the gaming-enhancement hypothesis

Directory of Open Access Journals (Sweden)

Andrew K. Przybylski

2016-11-01

Full Text Available A growing research literature suggests that regular electronic game play and game-based training programs may confer practically significant benefits to cognitive functioning. Most evidence supporting this idea, the gaming-enhancement hypothesis, has been collected in small-scale studies of university students and older adults. This research investigated the hypothesis in a general way with a large sample of 1,847 school-aged children. Our aim was to examine the relations between young people’s gaming experiences and an objective test of reasoning performance. Using a Bayesian hypothesis testing approach, evidence for the gaming-enhancement and null hypotheses were compared. Results provided no substantive evidence supporting the idea that having preference for or regularly playing commercially available games was positively associated with reasoning ability. Evidence ranged from equivocal to very strong in support for the null hypothesis over what was predicted. The discussion focuses on the value of Bayesian hypothesis testing for investigating electronic gaming effects, the importance of open science practices, and pre-registered designs to improve the quality of future work.

A large scale test of the gaming-enhancement hypothesis.

Science.gov (United States)

Przybylski, Andrew K; Wang, John C

2016-01-01

A growing research literature suggests that regular electronic game play and game-based training programs may confer practically significant benefits to cognitive functioning. Most evidence supporting this idea, the gaming-enhancement hypothesis , has been collected in small-scale studies of university students and older adults. This research investigated the hypothesis in a general way with a large sample of 1,847 school-aged children. Our aim was to examine the relations between young people's gaming experiences and an objective test of reasoning performance. Using a Bayesian hypothesis testing approach, evidence for the gaming-enhancement and null hypotheses were compared. Results provided no substantive evidence supporting the idea that having preference for or regularly playing commercially available games was positively associated with reasoning ability. Evidence ranged from equivocal to very strong in support for the null hypothesis over what was predicted. The discussion focuses on the value of Bayesian hypothesis testing for investigating electronic gaming effects, the importance of open science practices, and pre-registered designs to improve the quality of future work.

Advances in radiation epidemiology

International Nuclear Information System (INIS)

Boice, J.

1997-01-01

The 1994 UNSCEAR report provides an informative review of radiation epidemiology. During the past 2 years there have been several major advances in our understanding of radiation effects based on new studies of atomic bomb survivors in Japan, of patients given diagnostic and therapeutic radiation (including iodine-131), of workers occupationally exposed, and of general populations exposed to residential radon. Laboratory approaches are also being incorporated into epidemiological investigations to learn more about the biological mechanism by which radiation causes cancer in man. (author)

A Hypothesis-Driven Approach to Site Investigation

Science.gov (United States)

Nowak, W.

2008-12-01

Variability of subsurface formations and the scarcity of data lead to the notion of aquifer parameters as geostatistical random variables. Given an information need and limited resources for field campaigns, site investigation is often put into the context of optimal design. In optimal design, the types, numbers and positions of samples are optimized under case-specific objectives to meet the information needs. Past studies feature optimal data worth (balancing maximum financial profit in an engineering task versus the cost of additional sampling), or aim at a minimum prediction uncertainty of stochastic models for a prescribed investigation budget. Recent studies also account for other sources of uncertainty outside the hydrogeological range, such as uncertain toxicity, ingestion and behavioral parameters of the affected population when predicting the human health risk from groundwater contaminations. The current study looks at optimal site investigation from a new angle. Answering a yes/no question under uncertainty directly requires recasting the original question as a hypothesis test. Otherwise, false confidence in the resulting answer would be pretended. A straightforward example is whether a recent contaminant spill will cause contaminant concentrations in excess of a legal limit at a nearby drinking water well. This question can only be answered down to a specified chance of error, i.e., based on the significance level used in hypothesis tests. Optimal design is placed into the hypothesis-driven context by using the chance of providing a false yes/no answer as new criterion to be minimized. Different configurations apply for one-sided and two-sided hypothesis tests. If a false answer entails financial liability, the hypothesis-driven context can be re-cast in the context of data worth. The remaining difference is that failure is a hard constraint in the data worth context versus a monetary punishment term in the hypothesis-driven context. The basic principle

The (not so) immortal strand hypothesis.

Science.gov (United States)

Tomasetti, Cristian; Bozic, Ivana

2015-03-01

Non-random segregation of DNA strands during stem cell replication has been proposed as a mechanism to minimize accumulated genetic errors in stem cells of rapidly dividing tissues. According to this hypothesis, an "immortal" DNA strand is passed to the stem cell daughter and not the more differentiated cell, keeping the stem cell lineage replication error-free. After it was introduced, experimental evidence both in favor and against the hypothesis has been presented. Using a novel methodology that utilizes cancer sequencing data we are able to estimate the rate of accumulation of mutations in healthy stem cells of the colon, blood and head and neck tissues. We find that in these tissues mutations in stem cells accumulate at rates strikingly similar to those expected without the protection from the immortal strand mechanism. Utilizing an approach that is fundamentally different from previous efforts to confirm or refute the immortal strand hypothesis, we provide evidence against non-random segregation of DNA during stem cell replication. Our results strongly suggest that parental DNA is passed randomly to stem cell daughters and provides new insight into the mechanism of DNA replication in stem cells. Copyright © 2015. Published by Elsevier B.V.

Complex epidemiological approach to human mutagenesis

International Nuclear Information System (INIS)

Czeizel, A.

1980-01-01

The main characteristics of the epidemiological approach are summarised and the criteria discussed for the adoption of this approach for the detection of human mutagenesis. Mutation monitoring systems are described and results of epidemiological studies of higher risk populations are presented. (C.F.)

Retrospective study of epidemiological, clinicopathological and ...

African Journals Online (AJOL)

Retrospective study of epidemiological, clinicopathological and biological profils of 62 colorectal cancers cases in Jijel provence (Algeria) ... Our results were often compatible with the available literature and may provide reliable and relevant data on this disease. Key words: Colorectal cancer; Epidemiology; Therapy; ...

Rayleigh's hypothesis and the geometrical optics limit.

Science.gov (United States)

Elfouhaily, Tanos; Hahn, Thomas

2006-09-22

The Rayleigh hypothesis (RH) is often invoked in the theoretical and numerical treatment of rough surface scattering in order to decouple the analytical form of the scattered field. The hypothesis stipulates that the scattered field away from the surface can be extended down onto the rough surface even though it is formed by solely up-going waves. Traditionally this hypothesis is systematically used to derive the Volterra series under the small perturbation method which is equivalent to the low-frequency limit. In this Letter we demonstrate that the RH also carries the high-frequency or the geometrical optics limit, at least to first order. This finding has never been explicitly derived in the literature. Our result comforts the idea that the RH might be an exact solution under some constraints in the general case of random rough surfaces and not only in the case of small-slope deterministic periodic gratings.

[Occupational epidemiology: some methodological considerations].

Science.gov (United States)

Alvear-Galindo, María Guadalupe; del Pilar Paz-Román, María

2006-01-01

During the last decade, occupational epidemiology has gained a great importance, not only because of the increase of pollutants and their noxiousness, but also because it has gone from the descriptive to the analytic level. The purpose of this work is to present what has been reported on epidemiological studies, different ways of characterizing and measuring occupational exposure, by emphasizing slants of exposure and selection measurement. In the reviewed studies, an interest in improving the exposure evaluation has been shown. The mainly reported measurement slants are the ways of measuring and classifying the exposure. The main designs were transversal with the use of matrixes to improve the evaluation of exposure. Conditions of hygiene and security were considered in order to control the quality of the information. This information was analyzed with different criteria. Some of the elements that hinder the research on occupational epidemiology are a mixed exposure, small populations, lack of exposure data, low levels of exposure and long periods of illness latency. Some breakthroughs in the strategies of epidemiological analysis and some other areas of knowledge have made possible a better understanding of work and health conditions of workers.

Descriptive and analytic epidemiology. Bridges to cancer control

International Nuclear Information System (INIS)

Mettlin, C.

1988-01-01

Epidemiology serves as a bridge between basic science and cancer control. The two major orientations of epidemiology are descriptive and analytic. The former is useful in assessing the scope and dimensions of the cancer problem and the latter is used to assess environmental and lifestyle sources of cancer risk. A recent development in descriptive epidemiology is the use of functional measures of disease such as lost life expectancy. In analytical epidemiology, there is new or renewed interest in several lifestyle factors including diet and exercise as well as environmental factors such as involuntary tobacco exposure and radon in dwellings. Review of the evidence should consider the strengths and weaknesses of different research procedures. Each method is inconclusive by itself but, the different research designs of epidemiology collectively may represent a hierarchy of proof. Although the roles of many factors remain to be defined, the aggregate epidemiologic data continue to demonstrate the special importance of personal behavior and lifestyle in affecting cancer risk

Epidemiology in Germany-general development and personal experience.

Science.gov (United States)

Wichmann, Heinz-Erich

2017-08-01

Did you ever hear about epidemiology in Germany? Starting from an epidemiological desert the discipline has grown remarkably, especially during the last 10-15 years: research institutes have been established, research funding has improved, multiple curriculae in Epidemiology and Public Health are offered. This increase has been quite steep, and now the epidemiological infrastructure is much better. Several medium-sized and even big population cohorts are ongoing, and the number and quality of publications from German epidemiologists has reached a respectable level. My own career in epidemiology started in the field of environmental health. After German reunification I concentrated for many years on environmental problems in East Germany and observed the health benefits after improvement of the situation. Later, I concentrated on population-based cohorts in newborns (GINI/LISA) and adults (KORA, German National Cohort), and on biobanking. This Essay describes the development in Germany after worldwar 2, illustrated by examples of research results and build-up of epidemiological infractructures worth mentioning.

La epidemiología ocupacional como herramienta básica para la salud de los trabajadores Occupational epidemiology as a basic tool for workers' health

Directory of Open Access Journals (Sweden)

Caristina Robaina Aguirre

2006-06-01

Full Text Available Se realizó un pequeño bosquejo del desarrollo de la Epidemiología como ciencia y su importancia en salud pública en general. Se transita por las definiciones de vieja y nueva epidemiología, de enfermedades crónicas, transmisibles y no transmisibles, del concepto de epidemiología social, etc. para posteriormente hablar de la importancia de la Epidemiología Ocupacional en la Salud PúblicaA review of the development of Epidemiology as a science, and its significance in public health in general, was made. The old and new definitions of epidemiology, of chronic, transmissible and non-transmissible diseases, of social epidemiology concept, etc., are analysed to further deal with the importance of Occupational Epidemiology in Public Health.

A test of the reward-value hypothesis.

Science.gov (United States)

Smith, Alexandra E; Dalecki, Stefan J; Crystal, Jonathon D

2017-03-01

Rats retain source memory (memory for the origin of information) over a retention interval of at least 1 week, whereas their spatial working memory (radial maze locations) decays within approximately 1 day. We have argued that different forgetting functions dissociate memory systems. However, the two tasks, in our previous work, used different reward values. The source memory task used multiple pellets of a preferred food flavor (chocolate), whereas the spatial working memory task provided access to a single pellet of standard chow-flavored food at each location. Thus, according to the reward-value hypothesis, enhanced performance in the source memory task stems from enhanced encoding/memory of a preferred reward. We tested the reward-value hypothesis by using a standard 8-arm radial maze task to compare spatial working memory accuracy of rats rewarded with either multiple chocolate or chow pellets at each location using a between-subjects design. The reward-value hypothesis predicts superior accuracy for high-valued rewards. We documented equivalent spatial memory accuracy for high- and low-value rewards. Importantly, a 24-h retention interval produced equivalent spatial working memory accuracy for both flavors. These data are inconsistent with the reward-value hypothesis and suggest that reward value does not explain our earlier findings that source memory survives unusually long retention intervals.

The 'male escape hypothesis': sex-biased metamorphosis in response to climatic drivers in a facultatively paedomorphic amphibian.

Science.gov (United States)

Mathiron, Anthony G E; Lena, Jean-Paul; Baouch, Sarah; Denoël, Mathieu

2017-04-26

Paedomorphosis is a major evolutionary process that bypasses metamorphosis and allows reproduction in larvae. In newts and salamanders, it can be facultative with paedomorphs retaining gills and metamorphs dispersing. The evolution of these developmental processes is thought to have been driven by the costs and benefits of inhabiting aquatic versus terrestrial habitats. In this context, we aimed at testing the hypothesis that climatic drivers affect phenotypic transition and the difference across sexes because sex-ratio is biased in natural populations. Through a replicated laboratory experiment, we showed that paedomorphic palmate newts ( Lissotriton helveticus ) metamorphosed at a higher frequency when water availability decreased and metamorphosed earlier when temperature increased in these conditions. All responses were sex-biased, and males were more prone to change phenotype than females. Our work shows how climatic variables can affect facultative paedomorphosis and support theoretical models predicting life on land instead of in water. Moreover, because males metamorphose and leave water more often and earlier than females, these results, for the first time, give an experimental explanation for the rarity of male paedomorphosis (the 'male escape hypothesis') and suggest the importance of sex in the evolution of paedomorphosis versus metamorphosis. © 2017 The Author(s).

Epidemiological issues related to dose reconstruction

International Nuclear Information System (INIS)

Shore, R.E.

1996-01-01

When a dose reconstruction is performed around some nuclear site, a decision has to be made as to whether an epidemiologic study should be performed there and, if so, what form the study should take. The goal of this paper is to provide an overview of epidemiologic and biostatistical issues that help determine whether an epidemiologic study around a nuclear facility is worthwhile doing from a scientific standpoint. We are all aware that public health and sociopolitical concerns often assume considerable importance in these decisions, but they will not be considered here. 27 refs., 2 tabs

Nutrition transition and food sustainability.

Science.gov (United States)

Belahsen, Rekia

2014-08-01

The aim of the present paper is to review nutrition transition (NT) ongoing in low and middle income countries and the associated dietary changes. NT is accompanied by demographic and epidemiological transition associated with economic development and urbanisation. In these countries, while the problems of hunger and undernourishment persist, there is an escalation of diet-related non-communicable diseases; making them face both problems of malnutrition, under and overnutrition. Indeed, in addition to protein energy malnutrition underweight and micronutrient deficiencies affect a high proportion of children and women. Conversely, changes in dietary habits and physical activity patterns have led to emergence of chronic diseases such as obesity, diabetes, hypertension, stroke, hyperlipidaemia, CHD and cancer. One possible explanation of weight gain and its associated health consequences is the trend of the consumption of already prepared meals and the restaurants that are in continuous development leading to high consumption of foods rich in sugar and fat. The health problems associated with NT have not spared populations in the Mediterranean area where the type of diet is reported to be healthy and to protect against cardiovascular risks. This is seen in North Africa that belongs also to the Mediterranean basin, where the nutritional situation raises the problem of traditional foods sustainability. Accurate nutritional policy and education are needed to redress the effects of malnutrition related to NT on health.

Cannabis; Epidemiological, Neurobiological and Psychopathological Issues: An Update.

Science.gov (United States)

De Luca, Maria Antonietta; Di Chiara, Gaetano; Cadoni, Cristina; Lecca, Daniele; Orsolini, Laura; Papanti, Duccio; Corkery, John; Schifano, Fabrizio

2017-01-01

Cannabis is the illicit drug with both the largest current levels of consumption and the highest reported lifetime prevalence levels in the world. Across different countries, the prevalence of cannabis use varies according to the individual income, with the highest use being reported in North America, Australia and Europe. Despite its 'soft drug' reputation, cannabis misuse may be associated with several acute and chronic adverse effects. The present article aims at reviewing several papers on epidemiological, neurobiological and psychopathological aspects of the use of cannabis. The PubMed database was here examined in order to collect and discuss a range of identified papers. Cannabis intake usually starts during late adolescence/early adulthood (15-24 years) and drastically decreases in adulthood with the acquisition of working, familiar and social responsibilities. Clinical evidence supports the current socio-epidemiological alarm concerning the increased consumption among youngsters and the risks related to the onset of psychotic disorders. The mechanism of action of cannabis presents some analogies with other abused drugs, e.g. opiates. Furthermore, it has been well demonstrated that cannabis intake in adolescence may facilitate the transition to the use and/or abuse of other psychotropic drugs, hence properly being considered a 'gateway drug'. Some considerations on synthetic cannabimimetics are provided here as well. In conclusion, the highest prevalence of cannabis use and the social perception of a relatively low associated risk are in contrast with current knowledge based on biological and clinical evidence. Indeed, there are concerns relating to cannabis intake association with detrimental effects on both cognitive impairment and mental health. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Nuclear accidents and epidemiology

International Nuclear Information System (INIS)

1987-01-01

A consultation on epidemiology related to the Chernobyl accident was held in Copenhagen in May 1987 as a basis for concerted action. This was followed by a joint IAEA/WHO workshop in Vienna, which reviewed appropriate methodologies for possible long-term effects of radiation following nuclear accidents. The reports of these two meetings are included in this volume, and cover the subjects: 1) Epidemiology related to the Chernobyl nuclear accident. 2) Appropriate methodologies for studying possible long-term effects of radiation on individuals exposed in a nuclear accident. Figs and tabs

Semanticized autobiographical memory and the default - executive coupling hypothesis of aging.

Science.gov (United States)

Spreng, R Nathan; Lockrow, Amber W; DuPre, Elizabeth; Setton, Roni; Spreng, Karen A P; Turner, Gary R

2018-02-01

As we age, the architecture of cognition undergoes a fundamental transition. Fluid intellectual abilities decline while crystalized abilities remain stable or increase. This shift has a profound impact across myriad cognitive and functional domains, yet the neural mechanisms remain under-specified. We have proposed that greater connectivity between the default network and executive control regions in lateral prefrontal cortex may underlie this shift, as older adults increasingly rely upon accumulated knowledge to support goal-directed behavior. Here we provide direct evidence for this mechanism within the domain of autobiographical memory. In a large sample of healthy adult participants (n = 103 Young; n = 80 Old) the strength of default - executive coupling reliably predicted more semanticized, or knowledge-based, recollection of autobiographical memories in the older adult cohort. The findings are consistent with the default - executive coupling hypothesis of aging and identify this shift in network dynamics as a candidate neural mechanism associated with crystalized cognition in later life that may signal adaptive capacity in the context of declining fluid cognitive abilities. Copyright © 2017 Elsevier Ltd. All rights reserved.

Cancer Epidemiology Cohorts

Science.gov (United States)

Cohort studies are fundamental for epidemiological research by helping researchers better understand the etiology of cancer and provide insights into the key determinants of this disease and its outcomes.

Current Evidence to Justify, and the Methodological Considerations for a Randomised Controlled Trial Testing the Hypothesis that Statins Prevent the Malignant Progression of Barrett's Oesophagus

Directory of Open Access Journals (Sweden)

David Thurtle

2014-12-01

Full Text Available Barrett’s oesophagus is the predominant risk factor for oesophageal adenocarcinoma, a cancer whose incidence is increasing and which has a poor prognosis. This article reviews the latest experimental and epidemiological evidence justifying the development of a randomised controlled trial investigating the hypothesis that statins prevent the malignant progression of Barrett’s oesophagus, and explores the methodological considerations for such a trial. The experimental evidence suggests anti-carcinogenic properties of statins on oesophageal cancer cell lines, based on the inhibition of the mevalonate pathway and the production of pro-apoptotic proteins. The epidemiological evidence reports inverse associations between statin use and the incidence of oesophageal carcinoma in both general population and Barrett’s oesophagus cohorts. Such a randomised controlled trial would be a large multi-centre trial, probably investigating simvastatin, given the wide clinical experience with this drug, relatively low side-effect profile and low financial cost. As with any clinical trial, high adherence is important, which could be increased with therapy, patient, doctor and system-focussed interventions. We would suggest there is now sufficient evidence to justify a full clinical trial that attempts to prevent this aggressive cancer in a high-risk population.

Socioeconomic status and fertility decline: Insights from historical transitions in Europe and North America

Science.gov (United States)

Dribe, Martin; Breschi, Marco; Gagnon, Alain; Gauvreau, Danielle; Hanson, Heidi A.; Maloney, Thomas N.; Mazzoni, Stanislao; Molitoris, Joseph; Pozzi, Lucia; Smith, Ken R.; Vézina, Hélène

2016-01-01

We have good knowledge of the timing of the historical fertility transitions in different regions, but we know much less regarding specific features and causes. In this study, we used longitudinal micro-level data for five local populations in Europe and North America to study the relationship between socioeconomic status and fertility during the transition. Using the same analytical model and identical class scheme, we examined the development of socioeconomic differences in marital fertility and related it to common theories on fertility behaviour. Our results do not provide support for the hypothesis of universally high fertility among the upper classes in pre-transitional society but support the idea that they acted as forerunners in the transition by reducing their fertility before other groups. Farmers and unskilled workers were latest to start to limit their fertility. Apart from this regularity, the patterns of class differences in fertility varied significantly among populations. PMID:27884093

Transition radiation and transition scattering

International Nuclear Information System (INIS)

Ginzburg, V.L.

1982-01-01

Transition radiation is a process of a rather general character. It occurs when some source, which does not have a proper frequency (for example, a charge) moves at a constant velocity in an inhomogeneous and (or) nonstationary medium or near such a medium. The simplest type of transition radiation takes place when a charge crosses a boundary between two media (the role of one of the media may be played by vacuum). In the case of periodic variation of the medium, transition radiation possesses some specific features (resonance transition radiation or transition scattering). Transition scattering occurs, in particular, when a permittivity wave falls onto an nonmoving (fixed) charge. Transition scattering is closely connected with transition bremsstrahlung radiation. All these transition processes are essential for plasma physics. Transition radiation and transition scattering have analogues outside the framework of electrodynamics (like in the case of Vavilov-Cherenkov radiation). In the present report the corresponding range of phenomena is elucidated, as far as possible, in a generally physical aspect. (Auth.)

Motor synergies and the equilibrium-point hypothesis.

Science.gov (United States)

Latash, Mark L

2010-07-01

The article offers a way to unite three recent developments in the field of motor control and coordination: (1) The notion of synergies is introduced based on the principle of motor abundance; (2) The uncontrolled manifold hypothesis is described as offering a computational framework to identify and quantify synergies; and (3) The equilibrium-point hypothesis is described for a single muscle, single joint, and multijoint systems. Merging these concepts into a single coherent scheme requires focusing on control variables rather than performance variables. The principle of minimal final action is formulated as the guiding principle within the referent configuration hypothesis. Motor actions are associated with setting two types of variables by a controller, those that ultimately define average performance patterns and those that define associated synergies. Predictions of the suggested scheme are reviewed, such as the phenomenon of anticipatory synergy adjustments, quick actions without changes in synergies, atypical synergies, and changes in synergies with practice. A few models are briefly reviewed.

Learning-by-doing, population pressure, and the theory of demographic transition.

Science.gov (United States)

Strulik, H

1997-01-01

The long-term effects of two interdependent relations between economic growth and population growth are discussed. The empirical work of Boserup (1981) was utilized, which focused on rural, sparsely populated economies with low income per capita. According to the formulation of the population-push hypothesis, learning-by-doing effects in production lead to increasing returns to scale and, therefore, to a positive correlation between economic and population growth. In accordance with the theory of demographic transition, the population growth rate initially increases with rising income levels and then declines. The approach originating from Cigno (1984) modified the economic model, which allowed the establishment of two different stable equilibria. Regarding this relationship, the existence and stability of low-income and high-income equilibrium was shown in a neoclassical growth model. Under plausible conditions a demo-economic transition from the first to the second steady-state took place. The instability of the Malthusian steady-state is also possible when a country develops along a path of economic growth which is compatible with the demographic transition. In this context, learning means the application of new techniques of agrarian production. In developed economies with a stable population the learning-or-doing decision lead to accumulation of human capital and the invention of new technologies and goods. The interdependence of income-determined population growth and learning-by-doing may serve as an explanation for the weak and partly controversial empirical support for an overall correlation between income and population growth. The result yielded a meaningful interpretation of the population-push hypothesis, which is consistent with the empirical findings on the correlation between economic and population growth.

About the Epidemiology and Genomics Research Program

Science.gov (United States)

Epidemiology is the scientific study of the causes and distribution of disease in populations. NCI-funded epidemiology research is conducted through research at institutions in the United States and internationally.

Insecurities in employment and occupational careers and their impact on the transition to fatherhood in Western Germany

Directory of Open Access Journals (Sweden)

2003-09-01

Full Text Available This paper examines the relationship between work and family among men in Western Germany. We investigate the extent to which a difficult start in working life and insecurities during the working life affect men's transition to fatherhood, and how this effect is influenced by characteristics of the family of origin and the respondents' own relationship history. We use proportional hazards models to analyze data of the third "Familiensurvey" conducted by the German Youth Institute in 2000. In accordance with the spillover hypothesis which assumes that labor market success (or failure leads to success (or failure in family behavior as well, we found that under difficult and/or insecure circumstances in their career, men delay their transition to fatherhood. In particular, the delay was related to being unemployed, being self-employed or working part-time. On the other hand, a successful career development increases the propensity to have a child soon after the career step. Contrary to a hypothesis of individualization, the social status and the composition of the family of origin still have an impact on the fertility behavior of men in adulthood. In particular, the transition rate to fatherhood was higher if the man grew up with at least one sibling, while losing a parent through death decreased it. Both employment career and parental home influence the formation of steady relationships, which explains part of their effect on the transition to fatherhood.

Tests of the Giant Impact Hypothesis

Science.gov (United States)

Jones, J. H.

1998-01-01

The giant impact hypothesis has gained popularity as a means of explaining a volatile-depleted Moon that still has a chemical affinity to the Earth. As Taylor's Axiom decrees, the best models of lunar origin are testable, but this is difficult with the giant impact model. The energy associated with the impact would be sufficient to totally melt and partially vaporize the Earth. And this means that there should he no geological vestige of Barber times. Accordingly, it is important to devise tests that may be used to evaluate the giant impact hypothesis. Three such tests are discussed here. None of these is supportive of the giant impact model, but neither do they disprove it.

The globalization of epidemiology: introductory remarks.

Science.gov (United States)

Pearce, Neil

2004-10-01

We are all living in the era of globalization, and like it or not, it is going to change the way we practice epidemiology, the kinds of questions we ask, and the methods we use to answer them. Increasingly, pubic health problems are being shifted from rich countries to poor countries and from rich to poor populations within Western countries. There is increasing interest and concern about the situation in non-Western populations on the part of Western epidemiologists, with regards to collaborative research, skills transfer, and 'volunteerism' to enable the 'benefits' of Western approaches to epidemiology to be shared by the non-Western world. However, most existing collaborations benefit Western epidemiologists rather than the countries in which the research is conducted. Even when research in non-Western populations is conducted as a genuine collaboration, it can too often 'export failure' from the West. On the other hand, non-Western epidemiologists are increasingly developing new and innovative approaches to health research that are more appropriate to the global public health issues they are addressing. These include recognition of the importance of context and the importance of diversity and local knowledge, and a problem-based approach to addressing the major public health problems using appropriate technology. These debates formed the background for a plenary session on 'International Epidemiology and International Health' at the recent International Epidemiological Association (IEA) meeting in Montreal, and the papers from this session are presented here. The development of a truly global epidemiology can not only better address the public health problems in non-Western populations, but can shed light on the current limitations of epidemiology in addressing the major public health problems in the West.

Testing the null hypothesis: the forgotten legacy of Karl Popper?

Science.gov (United States)

Wilkinson, Mick

2013-01-01

Testing of the null hypothesis is a fundamental aspect of the scientific method and has its basis in the falsification theory of Karl Popper. Null hypothesis testing makes use of deductive reasoning to ensure that the truth of conclusions is irrefutable. In contrast, attempting to demonstrate the new facts on the basis of testing the experimental or research hypothesis makes use of inductive reasoning and is prone to the problem of the Uniformity of Nature assumption described by David Hume in the eighteenth century. Despite this issue and the well documented solution provided by Popper's falsification theory, the majority of publications are still written such that they suggest the research hypothesis is being tested. This is contrary to accepted scientific convention and possibly highlights a poor understanding of the application of conventional significance-based data analysis approaches. Our work should remain driven by conjecture and attempted falsification such that it is always the null hypothesis that is tested. The write up of our studies should make it clear that we are indeed testing the null hypothesis and conforming to the established and accepted philosophical conventions of the scientific method.

The Nutrition Transition in Africa: Can It Be Steered into a More Positive Direction?

Directory of Open Access Journals (Sweden)

Barrie M. Margetts

2011-04-01

Full Text Available The objective of this narrative review is to examine the nutrition transition and its consequences when populations in Africa modernize as a result of socio-economic development, urbanization, and acculturation. The focus is on the changes in dietary patterns and nutrient intakes during the nutrition transition, the determinants and consequences of these changes as well as possible new approaches in public health nutrition policies, interventions and research needed to steer the nutrition transition into a more positive direction in Africa. The review indicates that non-communicable, nutrition-related diseases have emerged in sub-Saharan Africa at a faster rate and at a lower economic level than in industrialized countries, before the battle against under-nutrition has been won. There is a putative epigenetic link between under- and over-nutrition, explaining the double burden of nutrition-related diseases in Africa. It is concluded that it is possible to steer the nutrition transition into a more positive direction, provided that some basic principles in planning public health promotion strategies, policies and interventions are followed. It is suggested that sub-Saharan African countries join forces to study the nutrition transition and implemented interventions on epidemiological, clinical and molecular (genetic level for better prevention of both under- and over-nutrition.

Methodological exploratory study applied to occupational epidemiology

Energy Technology Data Exchange (ETDEWEB)

Carneiro, Janete C.G. Gaburo; Vasques, MOnica Heloisa B.; Fontinele, Ricardo S.; Sordi, Gian Maria A. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)]. E-mail: janetegc@ipen.br

2007-07-01

The utilization of epidemiologic methods and techniques has been object of practical experimentation and theoretical-methodological reflection in health planning and programming process. Occupational Epidemiology is the study of the causes and prevention of diseases and injuries from exposition and risks in the work environment. In this context, there is no intention to deplete such a complex theme but to deal with basic concepts of Occupational Epidemiology, presenting the main characteristics of the analysis methods used in epidemiology, as investigate the possible determinants of exposition (chemical, physical and biological agents). For this study, the social-demographic profile of the IPEN-CNEN/SP work force was used. The knowledge of this reference population composition is based on sex, age, educational level, marital status and different occupations, aiming to know the relation between the health aggravating factors and these variables. The methodology used refers to a non-experimental research based on a theoretical methodological practice. The work performed has an exploratory character, aiming a later survey of indicators in the health area in order to analyze possible correlations related to epidemiologic issues. (author)

Methodological exploratory study applied to occupational epidemiology

International Nuclear Information System (INIS)

Carneiro, Janete C.G. Gaburo; Vasques, MOnica Heloisa B.; Fontinele, Ricardo S.; Sordi, Gian Maria A.

2007-01-01

The utilization of epidemiologic methods and techniques has been object of practical experimentation and theoretical-methodological reflection in health planning and programming process. Occupational Epidemiology is the study of the causes and prevention of diseases and injuries from exposition and risks in the work environment. In this context, there is no intention to deplete such a complex theme but to deal with basic concepts of Occupational Epidemiology, presenting the main characteristics of the analysis methods used in epidemiology, as investigate the possible determinants of exposition (chemical, physical and biological agents). For this study, the social-demographic profile of the IPEN-CNEN/SP work force was used. The knowledge of this reference population composition is based on sex, age, educational level, marital status and different occupations, aiming to know the relation between the health aggravating factors and these variables. The methodology used refers to a non-experimental research based on a theoretical methodological practice. The work performed has an exploratory character, aiming a later survey of indicators in the health area in order to analyze possible correlations related to epidemiologic issues. (author)

Longitudinal Physical Activity Patterns Among Older Adults: A Latent Transition Analysis.

Science.gov (United States)

Mooney, Stephen J; Joshi, Spruha; Cerdá, Magdalena; Kennedy, Gary J; Beard, John R; Rundle, Andrew G

2018-05-14

Most epidemiologic studies of physical activity measure either total energy expenditure or engagement in a single activity type, such as walking. These approaches may gloss over important nuances in activity patterns. We performed a latent transition analysis to identify patterns of activity types as well as neighborhood and individual determinants of changes in those activity patterns over two years in a cohort of 2,023 older adult residents of New York City, NY, surveyed between 2011 and 2013. We identified seven latent classes: 1) Mostly Inactive, 2) Walking, 3) Exercise, 4) Household Activities and Walking, 5) Household Activities and Exercise, 6) Gardening and Household Activities, and 7) Gardening, Household Activities, and Exercise. The majority of subjects retained the same activity patterns between waves (54% unchanged between waves 1 and 2, 66% unchanged between waves 2 and 3).Most latent class transitions were between classes distinguished only by one form of activity, and only neighborhood unemployment was consistently associated with changing between activity latent classes. Future latent transition analyses of physical activity would benefit from larger cohorts and longer follow-up periods to assess predictors of and long-term impacts of changes in activity patterns.

Mismatch or cumulative stress : Toward an integrated hypothesis of programming effects

NARCIS (Netherlands)

Nederhof, Esther; Schmidt, Mathias V.

2012-01-01

This paper integrates the cumulative stress hypothesis with the mismatch hypothesis, taking into account individual differences in sensitivity to programming. According to the cumulative stress hypothesis, individuals are more likely to suffer from disease as adversity accumulates. According to the

Monopole percolation and the universality class of the chiral transition in four flavor noncompact lattice QED

CERN Document Server

Kocic, Aleksandar; Wang, K C

1993-01-01

We simulate four flavor noncompact lattice QED using the Hybrid Monte Carlo algorithm on $10^4$ and $16^4$ lattices. Measurements of the monopole susceptibility and the percolation order parameter indicate a transition at $\\beta = {1/e^2} = .205(5)$ with critical behavior in the universality class of four dimensional percolation. We present accurate chiral condensate measurements and monitor finite size effects carefully. The chiral condensate data supports the existence of a power-law transition at $\\beta = .205$ in the same universality class as the chiral transition in the two flavor model. The resulting equation of state predicts the mass ratio $m_\\pi^2/m_\\sigma^2$ in good agreement with spectrum calculations while the hypothesis of a logarithmically improved mean field theory fails qualitatively.

Environmental policy without costs? A review of the Porter hypothesis

Energy Technology Data Exchange (ETDEWEB)

Braennlund, Runar; Lundgren, Tommy. e-mail: runar.brannlund@econ.umu.se

2009-03-15

This paper reviews the theoretical and empirical literature connected to the so called Porter Hypothesis. That is, to review the literature connected to the discussion about the relation between environmental policy and competitiveness. According to the conventional wisdom environmental policy, aiming for improving the environment through for example emission reductions, do imply costs since scarce resources must be diverted from somewhere else. However, this conventional wisdom has been challenged and questioned recently through what has been denoted the 'Porter hypothesis'. Those in the forefront of the Porter hypothesis challenge the conventional wisdom basically on the ground that resources are used inefficiently in the absence of the right kind of environmental regulations, and that the conventional neo-classical view is too static to take inefficiencies into account. The conclusions that can be made from this review is (1) that the theoretical literature can identify the circumstances and mechanisms that must exist for a Porter effect to occur, (2) that these circumstances are rather non-general, hence rejecting the Porter hypothesis in general, (3) that the empirical literature give no general support for the Porter hypothesis. Furthermore, a closer look at the 'Swedish case' reveals no support for the Porter hypothesis in spite of the fact that Swedish environmental policy the last 15-20 years seems to be in line the prerequisites stated by the Porter hypothesis concerning environmental policy

Coherent structure dynamics and identification during the multistage transitions of polymeric turbulent channel flow

Science.gov (United States)

Zhu, Lu; Xi, Li

2018-04-01

Drag reduction induced by polymer additives in wall-bounded turbulence has been studied for decades. A small dosage of polymer additives can drastically reduce the energy dissipation in turbulent flows and alter the flow structures at the same time. As the polymer-induced fluid elasticity increases, drag reduction goes through several stages of transition with drastically different flow statistics. While much attention in the area of polymer-turbulence interactions has been focused on the onset and the asymptotic stage of maximum drag reduction, the transition between the two intermediate stages – low-extent drag reduction (LDR) and high-extent drag reduction (HDR) – likely reflects a qualitative change in the underlying vortex dynamics according to our recent study [1]. In particular, we proposed that polymers start to suppress the lift-up and bursting of vortices at HDR, leading to the localization of turbulent structures. To test our hypothesis, a statistically robust conditional sampling algorithm, based on Jenong and Hussain [2]’s work, was adopted in this study. The comparison of conditional eddies between the Newtonian and the highly elastic turbulence shows that (i) the lifting “strength” of vortices is suppressed by polymers as reflected by the decreasing lifting angle of the conditional eddy and (ii) the curvature of vortices is also eliminated as the orientation of the head of the conditional eddy changes. In summary, the results of conditional sampling support our hypothesis of polymer-turbulence interactions during the LDR-HDR transition.

Chromium VI and stomach cancer: a meta-analysis of the current epidemiological evidence.

Science.gov (United States)

Welling, Roberta; Beaumont, James J; Petersen, Scott J; Alexeeff, George V; Steinmaus, Craig

2015-02-01

Chromium VI (hexavalent chromium, Cr(VI)) is an established cause of lung cancer, but its association with gastrointestinal cancer is less clear. The goal of this study was to examine whether the current human epidemiological research on occupationally inhaled Cr(VI) supports the hypothesis that Cr(VI) is associated with human stomach cancer. Following a thorough literature search and review of individual studies, we used meta-analysis to summarise the current epidemiological literature on inhaled Cr(VI) and stomach cancer, explore major sources of heterogeneity, and assess other elements of causal inference. We identified 56 cohort and case-control studies and 74 individual relative risk (RR) estimates on stomach cancer and Cr(VI) exposure or work in an occupation associated with high Cr(VI) exposure including chromium production, chrome plating, leather work and work with Portland cement. The summary RR for all studies combined was 1.27 (95% CI 1.18 to 1.38). In analyses limited to only those studies identifying increased risks of lung cancer, the summary RR for stomach cancer was higher (RR=1.41, 95% CI 1.18 to 1.69). Overall, these results suggest that Cr(VI) is a stomach carcinogen in humans, which is consistent with the tumour results reported in rodent studies. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

Epidemiology Without Biology: False Paradigms, Unfounded Assumptions, and Specious Statistics in Radiation Science (with Commentaries by Inge Schmitz-Feuerhake and Christopher Busby and a Reply by the Authors)

OpenAIRE

Sacks, Bill; Meyerson, Gregory; Siegel, Jeffry A.

2016-01-01

Radiation science is dominated by a paradigm based on an assumption without empirical foundation. Known as the linear no-threshold (LNT) hypothesis, it holds that all ionizing radiation is harmful no matter how low the dose or dose rate. Epidemiological studies that claim to confirm LNT either neglect experimental and/or observational discoveries at the cellular, tissue, and organismal levels, or mention them only to distort or dismiss them. The appearance of validity in these studies rests o...

A Design Support Framework through Dynamic Deployment of Hypothesis and Verification in the Design Process

Science.gov (United States)

Nomaguch, Yutaka; Fujita, Kikuo

This paper proposes a design support framework, named DRIFT (Design Rationale Integration Framework of Three layers), which dynamically captures and manages hypothesis and verification in the design process. A core of DRIFT is a three-layered design process model of action, model operation and argumentation. This model integrates various design support tools and captures design operations performed on them. Action level captures the sequence of design operations. Model operation level captures the transition of design states, which records a design snapshot over design tools. Argumentation level captures the process of setting problems and alternatives. The linkage of three levels enables to automatically and efficiently capture and manage iterative hypothesis and verification processes through design operations over design tools. In DRIFT, such a linkage is extracted through the templates of design operations, which are extracted from the patterns embeded in design tools such as Design-For-X (DFX) approaches, and design tools are integrated through ontology-based representation of design concepts. An argumentation model, gIBIS (graphical Issue-Based Information System), is used for representing dependencies among problems and alternatives. A mechanism of TMS (Truth Maintenance System) is used for managing multiple hypothetical design stages. This paper also demonstrates a prototype implementation of DRIFT and its application to a simple design problem. Further, it is concluded with discussion of some future issues.

Epidemiology of Schizophrenia: Review of Findings and Myths

OpenAIRE

Messias, Erick; Chen, Chuan-Yu; Eaton, William W.

2007-01-01

By describing patterns of disease distribution within populations, identifying risk factors, and finding associations, epidemiological studies have contributed to our current understanding of schizophrenia. Advanced paternal age and the association with auto-immune diseases are some of the newly described epidemiological finding in schizophrenia epidemiology, shaping our current definition of schizophrenia. Though early intervention strategies have gained momentum, primary prevention of schiz...

The world's high background natural radiation areas (HBNRAs) revisited: A broad overview of the dosimetric, epidemiological and radiobiological issues

International Nuclear Information System (INIS)

Aliyu, Abubakar Sadiq; Ramli, Ahmad Termizi

2015-01-01

The residents of the world's high background natural radiation areas (HBNRAs), such as Ramsar (in Iran), Guarapari (in Brazil), Orissa and Kerala (in India) and Yangjiang (in China) have lived in these areas for generations under extraordinary radiation fields. The failure of earlier epidemiological studies to report any substantial increase in cancer incidence in HBNRAs has raised some controversy regarding the validity of the linear no-threshold hypothesis. This paper reviews some of the most recent studies of HBNRAs with the intent of stimulating greater research interest in the dosimetric, epidemiological and radiobiological issues related to the world's HBNRAs and proposes solutions to the challenges facing HBNRA studies. This paper may serve as a useful reference for some of the harder-to-find literature. - Highlights: • Some of the challenging issues of HBNRAs have not been resolved. • A literature review of the most recent studies of HBNRAs has been conducted. • An overview of some of the challenging issues and viable solutions are presented

Occupational reproductive epidemiology: Pt. 1

International Nuclear Information System (INIS)

Roman, Eve; Doyle, Pat

1993-01-01

The authors review the current state of knowledge about possible adverse effects of hazardous paternal workplace exposures on human reproduction is scant. The methodology for studying possible association between occupational exposures and adverse reproductive events is not well developed. More detailed laboratory and epidemiological research is clearly required, and better collaboration between these two disciplines is needed. Associations suggested in the course of epidemiological research need to be tested in the laboratory, and vice versa. (author)

Epidemiology of idiopathic pulmonary fibrosis

Directory of Open Access Journals (Sweden)

Ley B

2013-11-01

Full Text Available Brett Ley, Harold R Collard Department of Medicine, Division of Pulmonary and Critical Care Medicine, University of California San Francisco, San Francisco, California, USA Abstract: Idiopathic pulmonary fibrosis is a chronic fibrotic lung disease of unknown cause that occurs in adults and has a poor prognosis. Its epidemiology has been difficult to study because of its rarity and evolution in diagnostic and coding practices. Though uncommon, it is likely underappreciated both in terms of its occurrence (ie, incidence, prevalence and public health impact (ie, health care costs and resource utilization. Incidence and mortality appear to be on the rise, and prevalence is expected to increase with the aging population. Potential risk factors include occupational and environmental exposures, tobacco smoking, gastroesophageal reflux, and genetic factors. An accurate understanding of its epidemiology is important, especially as novel therapies are emerging. Keywords: idiopathic pulmonary fibrosis, epidemiology, incidence, prevalence, mortality, risk factors

Implications of the Bohm-Aharonov hypothesis

International Nuclear Information System (INIS)

Ghirardi, G.C.; Rimini, A.; Weber, T.

1976-01-01

It is proved that the Bohm-Aharonov hypothesis concerning largerly separated subsystems of composite quantum systems implies that it is impossible to express the dynamical evolution in terms of the density operator

Radon epidemiology: A guide to the literature

International Nuclear Information System (INIS)

Marks, S.

1988-12-01

This document was written as a comprehensive overview of the voluminous literature on both uranium miner and residential radon epidemiology studies. This document provides the reader with a fairly complete list of radon epidemiology publications and key features of each, so that readers may further pursue only those publications of interest in the vast body of radon literature. A companion document, exploring all on-going residential radon epidemiology studies will be published by the Office of Health and Environmental Research (OHER), the Department of Energy (DOE) in the spring of 1989

Epidemiology of eating disorders in Africa.

Science.gov (United States)

van Hoeken, Daphne; Burns, Jonathan K; Hoek, Hans W

2016-11-01

This is the first review of studies on the epidemiology of eating disorders on the African continent. The majority of articles found through our search did not assess formal diagnoses, but only screened for eating attitudes and behaviors. Only four studies - including only one recent study - provided specific epidemiological data on anorexia nervosa, bulimia nervosa, and/or eating disorder not otherwise specified (EDNOS). No cases of anorexia nervosa according to Diagnostic and Statistical Manual of Mental Disorders (DSM)-IV criteria were found among a total of 1476 (young) females. The combined point-prevalence rate of bulimia nervosa is 0.87% (95% CI 0.22-1.51) and of EDNOS is 4.45% (95% CI 2.74-6.16) in young women in Africa. The epidemiological study of eating disorders in Africa is still in its infancy. Over time in total four studies providing epidemiological data on specific, formally assessed eating disorders were found. No cases of anorexia nervosa were reported in African epidemiological studies, which concurs with the very low prevalence rates of anorexia nervosa in Latin Americans and in African Americans in the USA. With the DSM-5 criteria for anorexia nervosa, some women in the African studies would have fulfilled the criteria for anorexia nervosa. The prevalence rate of bulimia nervosa in women in Africa is within the range reported for western populations, as well as African Americans and Latin Americans.

Almost-Quantum Correlations Violate the No-Restriction Hypothesis.

Science.gov (United States)

Sainz, Ana Belén; Guryanova, Yelena; Acín, Antonio; Navascués, Miguel

2018-05-18

To identify which principles characterize quantum correlations, it is essential to understand in which sense this set of correlations differs from that of almost-quantum correlations. We solve this problem by invoking the so-called no-restriction hypothesis, an explicit and natural axiom in many reconstructions of quantum theory stating that the set of possible measurements is the dual of the set of states. We prove that, contrary to quantum correlations, no generalized probabilistic theory satisfying the no-restriction hypothesis is able to reproduce the set of almost-quantum correlations. Therefore, any theory whose correlations are exactly, or very close to, the almost-quantum correlations necessarily requires a rule limiting the possible measurements. Our results suggest that the no-restriction hypothesis may play a fundamental role in singling out the set of quantum correlations among other nonsignaling ones.

The Lévy flight foraging hypothesis: forgetting about memory may lead to false verification of Brownian motion.

Science.gov (United States)

Gautestad, Arild O; Mysterud, Atle

2013-01-01

The Lévy flight foraging hypothesis predicts a transition from scale-free Lévy walk (LW) to scale-specific Brownian motion (BM) as an animal moves from resource-poor towards resource-rich environment. However, the LW-BM continuum implies a premise of memory-less search, which contradicts the cognitive capacity of vertebrates. We describe methods to test if apparent support for LW-BM transitions may rather be a statistical artifact from movement under varying intensity of site fidelity. A higher frequency of returns to previously visited patches (stronger site fidelity) may erroneously be interpreted as a switch from LW towards BM. Simulations of scale-free, memory-enhanced space use illustrate how the ratio between return events and scale-free exploratory movement translates to varying strength of site fidelity. An expanded analysis of GPS data of 18 female red deer, Cervus elaphus, strengthens previous empirical support of memory-enhanced and scale-free space use in a northern forest ecosystem. A statistical mechanical model architecture that describes foraging under environment-dependent variation of site fidelity may allow for higher realism of optimal search models and movement ecology in general, in particular for vertebrates with high cognitive capacity.

Assess the Critical Period Hypothesis in Second Language Acquisition

Science.gov (United States)

Du, Lihong

2010-01-01

The Critical Period Hypothesis aims to investigate the reason for significant difference between first language acquisition and second language acquisition. Over the past few decades, researchers carried out a series of studies to test the validity of the hypothesis. Although there were certain limitations in these studies, most of their results…

Human Inferences about Sequences: A Minimal Transition Probability Model.

Directory of Open Access Journals (Sweden)

Florent Meyniel

2016-12-01

Full Text Available The brain constantly infers the causes of the inputs it receives and uses these inferences to generate statistical expectations about future observations. Experimental evidence for these expectations and their violations include explicit reports, sequential effects on reaction times, and mismatch or surprise signals recorded in electrophysiology and functional MRI. Here, we explore the hypothesis that the brain acts as a near-optimal inference device that constantly attempts to infer the time-varying matrix of transition probabilities between the stimuli it receives, even when those stimuli are in fact fully unpredictable. This parsimonious Bayesian model, with a single free parameter, accounts for a broad range of findings on surprise signals, sequential effects and the perception of randomness. Notably, it explains the pervasive asymmetry between repetitions and alternations encountered in those studies. Our analysis suggests that a neural machinery for inferring transition probabilities lies at the core of human sequence knowledge.

Relation of motor, linguistic and temperament factors in epidemiologic subtypes of persistent and recovered stuttering: Initial findings.

Science.gov (United States)

Ambrose, Nicoline G; Yairi, Ehud; Loucks, Torrey M; Seery, Carol Hubbard; Throneburg, Rebecca

2015-09-01

The purpose of this study was to determine the presence of any patterns reflecting underlying subtypes of persistence and recovery across epidemiologic, motor, language, and temperament domains in the same group of children beginning to stutter and followed for several years. Participants were 58 2-4-year-old CWS and 40 age and gender matched NFC from four different sites in the Midwest. At the end of the multi-year study, stuttering children were classified as Persistent or Recovered. The same protocol obtaining data to measure stuttering, motor, language and temperament characteristics was used at each site. They have not been included in previous reports. The Persistent group performed consistently differently from the Recovered and Control groups. They performed lower on standardized language tests and in phonological accuracy, had greater kinematic variability, and were judged by their parents to be more negative in temperament. The present study provides data supporting the hypothesis that subtypes of stuttering can be identified along persistency/recovery lines, but results were not definitive. Readers will be able to (a) describe the current state of subtypes of stuttering research; (b) summarize possible contributions of epidemiologic, motoric, linguistic and temperament to such subtyping with regard to persistency and recovery. Copyright © 2015 Elsevier Inc. All rights reserved.

Epidemiology of extremity fractures in the Netherlands

NARCIS (Netherlands)

Beerekamp, M. S. H.; de Muinck Keizer, R. J. O.; Schep, N. W. L.; Ubbink, D. T.; Panneman, M. J. M.; Goslings, J. C.

2017-01-01

Insight in epidemiologic data of extremity fractures is relevant to identify people at risk. By analyzing age- and gender specific fracture incidence and treatment patterns we may adjust future policy, take preventive measures and optimize health care management. Current epidemiologic data on

Epidemiological reference ranges for low-density lipoprotein ...

African Journals Online (AJOL)

Although there is widespread acceptance that total cholesterol (TC) value reference ranges should be based on epidemiological rather than statistical considerations, the epidemiological action limits for Iow-density lipoprotein cholesterol (LDL-C) are still incomplete and only statistical reference ranges for apolipoprotein B ...

An alternative analysis of apparent EKC-type transitions

International Nuclear Information System (INIS)

Unruh, G.C.; Moomaw, W.R.

1998-01-01

The hypothesis of the environmental Kuznets curve (EKC) depends upon the assumption that countries pass through a similar environmental impact trajectory as they experience income growth, implying that income levels determine pollution levels. The authors present evidence that this is not representative of the way many individual country's pollution emission trajectories evolve and question the emphasis on 'income determinism' by the EKC. The study proposes that nonlinear dynamic systems analysis provides a more complete description of individual country pollution trajectories. In the case of CO 2 emissions, the nonlinear time trajectories show abrupt transitions that occur contemporaneously with historical events and over a broad range of incomes

Maximal Repetitions in Written Texts: Finite Energy Hypothesis vs. Strong Hilberg Conjecture

Directory of Open Access Journals (Sweden)

Łukasz Dębowski

2015-08-01

Full Text Available The article discusses two mutually-incompatible hypotheses about the stochastic mechanism of the generation of texts in natural language, which could be related to entropy. The first hypothesis, the finite energy hypothesis, assumes that texts are generated by a process with exponentially-decaying probabilities. This hypothesis implies a logarithmic upper bound for maximal repetition, as a function of the text length. The second hypothesis, the strong Hilberg conjecture, assumes that the topological entropy grows as a power law. This hypothesis leads to a hyperlogarithmic lower bound for maximal repetition. By a study of 35 written texts in German, English and French, it is found that the hyperlogarithmic growth of maximal repetition holds for natural language. In this way, the finite energy hypothesis is rejected, and the strong Hilberg conjecture is partly corroborated.

The Stoichiometric Divisome: A Hypothesis

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Waldemar eVollmer

2015-05-01

Full Text Available Dividing Escherichia coli cells simultaneously constrict the inner membrane, peptidoglycan layer and outer membrane to synthesize the new poles of the daughter cells. For this, more than 30 proteins localize to mid-cell where they form a large, ring-like assembly, the divisome, facilitating division. Although the precise function of most divisome proteins is unknown, it became apparent in recent years that dynamic protein-protein interactions are essential for divisome assembly and function. However, little is known about the nature of the interactions involved and the stoichiometry of the proteins within the divisome. A recent study (Li et al., 2014 used ribosome profiling to measure the absolute protein synthesis rates in E. coli. Interestingly, they observed that most proteins which participate in known multiprotein complexes are synthesized proportional to their stoichiometry. Based on this principle we present a hypothesis for the stoichiometry of the core of the divisome, taking into account known protein-protein interactions. From this hypothesis we infer a possible mechanism for PG synthesis during division.

The Fractal Market Hypothesis: Applications to Financial Forecasting

OpenAIRE

Blackledge, Jonathan

2010-01-01

Most financial modelling systems rely on an underlying hypothesis known as the Efficient Market Hypothesis (EMH) including the famous Black-Scholes formula for placing an option. However, the EMH has a fundamental flaw: it is based on the assumption that economic processes are normally distributed and it has long been known that this is not the case. This fundamental assumption leads to a number of shortcomings associated with using the EMH to analyse financial data which includes failure to ...

Spatial evolutionary epidemiology of spreading epidemics.

Science.gov (United States)

Lion, S; Gandon, S

2016-10-26

Most spatial models of host-parasite interactions either neglect the possibility of pathogen evolution or consider that this process is slow enough for epidemiological dynamics to reach an equilibrium on a fast timescale. Here, we propose a novel approach to jointly model the epidemiological and evolutionary dynamics of spatially structured host and pathogen populations. Starting from a multi-strain epidemiological model, we use a combination of spatial moment equations and quantitative genetics to analyse the dynamics of mean transmission and virulence in the population. A key insight of our approach is that, even in the absence of long-term evolutionary consequences, spatial structure can affect the short-term evolution of pathogens because of the build-up of spatial differentiation in mean virulence. We show that spatial differentiation is driven by a balance between epidemiological and genetic effects, and this quantity is related to the effect of kin competition discussed in previous studies of parasite evolution in spatially structured host populations. Our analysis can be used to understand and predict the transient evolutionary dynamics of pathogens and the emergence of spatial patterns of phenotypic variation. © 2016 The Author(s).

Contact networks structured by sex underpin sex-specific epidemiology of infection.

Science.gov (United States)

Silk, Matthew J; Weber, Nicola L; Steward, Lucy C; Hodgson, David J; Boots, Mike; Croft, Darren P; Delahay, Richard J; McDonald, Robbie A

2018-02-01

Contact networks are fundamental to the transmission of infection and host sex often affects the acquisition and progression of infection. However, the epidemiological impacts of sex-related variation in animal contact networks have rarely been investigated. We test the hypothesis that sex-biases in infection are related to variation in multilayer contact networks structured by sex in a population of European badgers Meles meles naturally infected with Mycobacterium bovis. Our key results are that male-male and between-sex networks are structured at broader spatial scales than female-female networks and that in male-male and between-sex contact networks, but not female-female networks, there is a significant relationship between infection and contacts with individuals in other groups. These sex differences in social behaviour may underpin male-biased acquisition of infection and may result in males being responsible for more between-group transmission. This highlights the importance of sex-related variation in host behaviour when managing animal diseases. © 2017 The Authors. Ecology Letters published by CNRS and John Wiley & Sons Ltd.

Molecular epidemiology of human rhinoviruses

OpenAIRE

Savolainen-Kopra, Carita

2006-01-01

The first part of this work investigates the molecular epidemiology of a human enterovirus (HEV), echovirus 30 (E-30). This project is part of a series of studies performed in our research team analyzing the molecular epidemiology of HEV-B viruses. A total of 129 virus strains had been isolated in different parts of Europe. The sequence analysis was performed in three different genomic regions: 420 nucleotides (nt) in the VP4/VP2 capsid protein coding region, the entire VP1 capsid protein cod...

[Working memory, phonological awareness and spelling hypothesis].

Science.gov (United States)

Gindri, Gigiane; Keske-Soares, Márcia; Mota, Helena Bolli

2007-01-01

Working memory, phonological awareness and spelling hypothesis. To verify the relationship between working memory, phonological awareness and spelling hypothesis in pre-school children and first graders. Participants of this study were 90 students, belonging to state schools, who presented typical linguistic development. Forty students were preschoolers, with the average age of six and 50 students were first graders, with the average age of seven. Participants were submitted to an evaluation of the working memory abilities based on the Working Memory Model (Baddeley, 2000), involving phonological loop. Phonological loop was evaluated using the Auditory Sequential Test, subtest 5 of Illinois Test of Psycholinguistic Abilities (ITPA), Brazilian version (Bogossian & Santos, 1977), and the Meaningless Words Memory Test (Kessler, 1997). Phonological awareness abilities were investigated using the Phonological Awareness: Instrument of Sequential Assessment (CONFIAS - Moojen et al., 2003), involving syllabic and phonemic awareness tasks. Writing was characterized according to Ferreiro & Teberosky (1999). Preschoolers presented the ability of repeating sequences of 4.80 digits and 4.30 syllables. Regarding phonological awareness, the performance in the syllabic level was of 19.68 and in the phonemic level was of 8.58. Most of the preschoolers demonstrated to have a pre-syllabic writing hypothesis. First graders repeated, in average, sequences of 5.06 digits and 4.56 syllables. These children presented a phonological awareness of 31.12 in the syllabic level and of 16.18 in the phonemic level, and demonstrated to have an alphabetic writing hypothesis. The performance of working memory, phonological awareness and spelling level are inter-related, as well as being related to chronological age, development and scholarity.

On Using Taylor's Hypothesis for Three-Dimensional Mixing Layers

Science.gov (United States)

LeBoeuf, Richard L.; Mehta, Rabindra D.

1995-01-01

In the present study, errors in using Taylor's hypothesis to transform measurements obtained in a temporal (or phase) frame onto a spatial one were evaluated. For the first time, phase-averaged ('real') spanwise and streamwise vorticity data measured on a three-dimensional grid were compared directly to those obtained using Taylor's hypothesis. The results show that even the qualitative features of the spanwise and streamwise vorticity distributions given by the two techniques can be very different. This is particularly true in the region of the spanwise roller pairing. The phase-averaged spanwise and streamwise peak vorticity levels given by Taylor's hypothesis are typically lower (by up to 40%) compared to the real measurements.

A test of the reward-contrast hypothesis.

Science.gov (United States)

Dalecki, Stefan J; Panoz-Brown, Danielle E; Crystal, Jonathon D

2017-12-01

Source memory, a facet of episodic memory, is the memory of the origin of information. Whereas source memory in rats is sustained for at least a week, spatial memory degraded after approximately a day. Different forgetting functions may suggest that two memory systems (source memory and spatial memory) are dissociated. However, in previous work, the two tasks used baiting conditions consisting of chocolate and chow flavors; notably, the source memory task used the relatively better flavor. Thus, according to the reward-contrast hypothesis, when chocolate and chow were presented within the same context (i.e., within a single radial maze trial), the chocolate location was more memorable than the chow location because of contrast. We tested the reward-contrast hypothesis using baiting configurations designed to produce reward-contrast. The reward-contrast hypothesis predicts that under these conditions, spatial memory will survive a 24-h retention interval. We documented elimination of spatial memory performance after a 24-h retention interval using a reward-contrast baiting pattern. These data suggest that reward contrast does not explain our earlier findings that source memory survives unusually long retention intervals. Copyright © 2017 Elsevier B.V. All rights reserved.

Eye Disease and Development

DEFF Research Database (Denmark)

Andersen, Thomas Barnebeck; Dalgaard, Carl-Johan Lars; Selaya, Pablo

This research advances the hypothesis that cross-country variation in the historical incidence of eye disease has influenced the current global distribution of per capita income. The theory is that pervasive eye disease diminished the incentive to accumulate skills, thereby delaying the fertility...... transition and the take-off to sustained economic growth. In order to estimate the influence from eye disease incidence empirically, we draw on an important fact from the field of epidemiology: Exposure to solar ultraviolet B radiation (UVB-R) is an underlying determinant of several forms of eye disease...

Metastable liquid-liquid transition in a molecular model of water

Science.gov (United States)

Palmer, Jeremy C.; Martelli, Fausto; Liu, Yang; Car, Roberto; Panagiotopoulos, Athanassios Z.; Debenedetti, Pablo G.

2014-06-01

Liquid water's isothermal compressibility and isobaric heat capacity, and the magnitude of its thermal expansion coefficient, increase sharply on cooling below the equilibrium freezing point. Many experimental, theoretical and computational studies have sought to understand the molecular origin and implications of this anomalous behaviour. Of the different theoretical scenarios put forward, one posits the existence of a first-order phase transition that involves two forms of liquid water and terminates at a critical point located at deeply supercooled conditions. Some experimental evidence is consistent with this hypothesis, but no definitive proof of a liquid-liquid transition in water has been obtained to date: rapid ice crystallization has so far prevented decisive measurements on deeply supercooled water, although this challenge has been overcome recently. Computer simulations are therefore crucial for exploring water's structure and behaviour in this regime, and have shown that some water models exhibit liquid-liquid transitions and others do not. However, recent work has argued that the liquid-liquid transition has been mistakenly interpreted, and is in fact a liquid-crystal transition in all atomistic models of water. Here we show, by studying the liquid-liquid transition in the ST2 model of water with the use of six advanced sampling methods to compute the free-energy surface, that two metastable liquid phases and a stable crystal phase exist at the same deeply supercooled thermodynamic condition, and that the transition between the two liquids satisfies the thermodynamic criteria of a first-order transition. We follow the rearrangement of water's coordination shell and topological ring structure along a thermodynamically reversible path from the low-density liquid to cubic ice. We also show that the system fluctuates freely between the two liquid phases rather than crystallizing. These findings provide unambiguous evidence for a liquid-liquid transition in

Cardiovascular risk status of Afro-origin populations across the spectrum of economic development: findings from the Modeling the Epidemiologic Transition Study.

Science.gov (United States)

Dugas, Lara R; Forrester, Terrence E; Plange-Rhule, Jacob; Bovet, Pascal; Lambert, Estelle V; Durazo-Arvizu, Ramon A; Cao, Guichan; Cooper, Richard S; Khatib, Rasha; Tonino, Laura; Riesen, Walter; Korte, Wolfgang; Kliethermes, Stephanie; Luke, Amy

2017-05-12

Cardiovascular risk factors are increasing in most developing countries. To date, however, very little standardized data has been collected on the primary risk factors across the spectrum of economic development. Data are particularly sparse from Africa. In the Modeling the Epidemiologic Transition Study (METS) we examined population-based samples of men and women, ages 25-45 of African ancestry in metropolitan Chicago, Kingston, Jamaica, rural Ghana, Cape Town, South Africa, and the Seychelles. Key measures of cardiovascular disease risk are described. The risk factor profile varied widely in both total summary estimates of cardiovascular risk and in the magnitude of component factors. Hypertension ranged from 7% in women from Ghana to 35% in US men. Total cholesterol was well under 200 mg/dl for all groups, with a mean of 155 mg/dl among men in Ghana, South Africa and Jamaica. Among women total cholesterol values varied relatively little by country, following between 160 and 178 mg/dl for all 5 groups. Levels of HDL-C were virtually identical in men and women from all study sites. Obesity ranged from 64% among women in the US to 2% among Ghanaian men, with a roughly corresponding trend in diabetes. Based on the Framingham risk score a clear trend toward higher total risk in association with socioeconomic development was observed among men, while among women there was considerable overlap, with the US participants having only a modestly higher risk score. These data provide a comprehensive estimate of cardiovascular risk across a range of countries at differing stages of social and economic development and demonstrate the heterogeneity in the character and degree of emerging cardiovascular risk. Severe hypercholesterolemia, as characteristic in the US and much of Western Europe at the onset of the coronary epidemic, is unlikely to be a feature of the cardiovascular risk profile in these countries in the foreseeable future, suggesting that stroke may remain the

Cardiovascular risk status of Afro-origin populations across the spectrum of economic development: findings from the Modeling the Epidemiologic Transition Study

Directory of Open Access Journals (Sweden)

Lara R. Dugas

2017-05-01

Full Text Available Abstract Background Cardiovascular risk factors are increasing in most developing countries. To date, however, very little standardized data has been collected on the primary risk factors across the spectrum of economic development. Data are particularly sparse from Africa. Methods In the Modeling the Epidemiologic Transition Study (METS we examined population-based samples of men and women, ages 25–45 of African ancestry in metropolitan Chicago, Kingston, Jamaica, rural Ghana, Cape Town, South Africa, and the Seychelles. Key measures of cardiovascular disease risk are described. Results The risk factor profile varied widely in both total summary estimates of cardiovascular risk and in the magnitude of component factors. Hypertension ranged from 7% in women from Ghana to 35% in US men. Total cholesterol was well under 200 mg/dl for all groups, with a mean of 155 mg/dl among men in Ghana, South Africa and Jamaica. Among women total cholesterol values varied relatively little by country, following between 160 and 178 mg/dl for all 5 groups. Levels of HDL-C were virtually identical in men and women from all study sites. Obesity ranged from 64% among women in the US to 2% among Ghanaian men, with a roughly corresponding trend in diabetes. Based on the Framingham risk score a clear trend toward higher total risk in association with socioeconomic development was observed among men, while among women there was considerable overlap, with the US participants having only a modestly higher risk score. Conclusions These data provide a comprehensive estimate of cardiovascular risk across a range of countries at differing stages of social and economic development and demonstrate the heterogeneity in the character and degree of emerging cardiovascular risk. Severe hypercholesterolemia, as characteristic in the US and much of Western Europe at the onset of the coronary epidemic, is unlikely to be a feature of the cardiovascular risk profile in these

Controls on the abruptness of gravel-sand transitions

Science.gov (United States)

Venditti, J. G.; Church, M. A.; Lamb, M. P.; Domarad, N.; Rennie, C. D.

2014-12-01

As gravel-bedded rivers fine downstream, they characteristically exhibit an abrupt transition from gravel- to sand-bed. This is the only abrupt transition in grain-size that occurs in the fluvial system and has attracted considerable attention. A number of competing theories have been proposed to account for the abruptness of the transition, including base-level control, attrition of ~10mm gravel to produce sand, and sediment sorting processes. The prevailing theory for the emergence of abrupt transitions is size selective sorting of bimodal sediment wherein gravel deposits due to downstream declining shear stress, fining the bedload until a sand-bed emerges. We explored this hypothesis by examining grain-size, shear stress, gravel mobility and sand suspension thresholds through the gravel-sand transition (GST) of the Fraser River, British Columbia. The Fraser GST is an arrested gravel wedge with patches of gravel downstream of the wedge forming a diffuse extension. There is an abrupt change in bed slope through the transition that leads to an abrupt change in shear stress. The GST, bed-slope change and backwater caused by the ocean are all coincident spatially, which enhances the sharpness of the GST. Interestingly, the bimodal reach of the river occurs downstream of the GST and exhibits no downstream gradients in shear stress, suspended sediment flux, gravel mobility or sand suspension thresholds. This calls into question the prevailing theory for the emergence of an abrupt GST by size selective sorting. We provide evidence, both empirical and theoretical, that suggests the emergence of an abrupt GST is caused by rapid deposition of sand when fine gravel deposits. We argue that the emergence of gravel-sand transitions is a consequence of gravel-bedded rivers adopting a steeper slope than sand-bedded rivers. The abruptness arises because the bed slope required to convey the gravel load fixes the distal location of a terminal gravel wedge, and once the river has

Cultural epidemiology: An introduction and overview

OpenAIRE

Weiss, Mitchell Gralnick

2001-01-01

Although the value of interdisciplinary collaboration between epidemiology and anthropology is both widely acknowledged and hotly contested, effective international health policy and multicultural health programmes require it. The EMIC framework for cultural studies of illness was developed in response to such needs, and a cultural epidemiology emerged from that framework as an interdisciplinary field of research on locally valid representations of illness and their distributions in cultural ...

An Exercise for Illustrating the Logic of Hypothesis Testing

Science.gov (United States)

Lawton, Leigh

2009-01-01

Hypothesis testing is one of the more difficult concepts for students to master in a basic, undergraduate statistics course. Students often are puzzled as to why statisticians simply don't calculate the probability that a hypothesis is true. This article presents an exercise that forces students to lay out on their own a procedure for testing a…

The Drift Burst Hypothesis

OpenAIRE

Christensen, Kim; Oomen, Roel; Renò, Roberto

2016-01-01

The Drift Burst Hypothesis postulates the existence of short-lived locally explosive trends in the price paths of financial assets. The recent US equity and Treasury flash crashes can be viewed as two high profile manifestations of such dynamics, but we argue that drift bursts of varying magnitude are an expected and regular occurrence in financial markets that can arise through established mechanisms such as feedback trading. At a theoretical level, we show how to build drift bursts into the...

P value and the theory of hypothesis testing: an explanation for new researchers.

Science.gov (United States)

Biau, David Jean; Jolles, Brigitte M; Porcher, Raphaël

2010-03-01

In the 1920s, Ronald Fisher developed the theory behind the p value and Jerzy Neyman and Egon Pearson developed the theory of hypothesis testing. These distinct theories have provided researchers important quantitative tools to confirm or refute their hypotheses. The p value is the probability to obtain an effect equal to or more extreme than the one observed presuming the null hypothesis of no effect is true; it gives researchers a measure of the strength of evidence against the null hypothesis. As commonly used, investigators will select a threshold p value below which they will reject the null hypothesis. The theory of hypothesis testing allows researchers to reject a null hypothesis in favor of an alternative hypothesis of some effect. As commonly used, investigators choose Type I error (rejecting the null hypothesis when it is true) and Type II error (accepting the null hypothesis when it is false) levels and determine some critical region. If the test statistic falls into that critical region, the null hypothesis is rejected in favor of the alternative hypothesis. Despite similarities between the two, the p value and the theory of hypothesis testing are different theories that often are misunderstood and confused, leading researchers to improper conclusions. Perhaps the most common misconception is to consider the p value as the probability that the null hypothesis is true rather than the probability of obtaining the difference observed, or one that is more extreme, considering the null is true. Another concern is the risk that an important proportion of statistically significant results are falsely significant. Researchers should have a minimum understanding of these two theories so that they are better able to plan, conduct, interpret, and report scientific experiments.

Epidemiology, diagnosis and management of food allergy

NARCIS (Netherlands)

Le, T.T.M.

2013-01-01

This thesis describes the epidemiology, diagnosis and management of food allergy. Epidemiology This thesis shows that the prevalence of self-reported adverse food reactions in children and adults was high: 17-25% for all foods and 10-11% for 24 preselected, so-called priority foods. The prevalence

MOLIERE: Automatic Biomedical Hypothesis Generation System.

Science.gov (United States)

Sybrandt, Justin; Shtutman, Michael; Safro, Ilya

2017-08-01

Hypothesis generation is becoming a crucial time-saving technique which allows biomedical researchers to quickly discover implicit connections between important concepts. Typically, these systems operate on domain-specific fractions of public medical data. MOLIERE, in contrast, utilizes information from over 24.5 million documents. At the heart of our approach lies a multi-modal and multi-relational network of biomedical objects extracted from several heterogeneous datasets from the National Center for Biotechnology Information (NCBI). These objects include but are not limited to scientific papers, keywords, genes, proteins, diseases, and diagnoses. We model hypotheses using Latent Dirichlet Allocation applied on abstracts found near shortest paths discovered within this network, and demonstrate the effectiveness of MOLIERE by performing hypothesis generation on historical data. Our network, implementation, and resulting data are all publicly available for the broad scientific community.

Debates—Hypothesis testing in hydrology: Introduction

Science.gov (United States)

Blöschl, Günter

2017-03-01

This paper introduces the papers in the "Debates—Hypothesis testing in hydrology" series. The four articles in the series discuss whether and how the process of testing hypotheses leads to progress in hydrology. Repeated experiments with controlled boundary conditions are rarely feasible in hydrology. Research is therefore not easily aligned with the classical scientific method of testing hypotheses. Hypotheses in hydrology are often enshrined in computer models which are tested against observed data. Testability may be limited due to model complexity and data uncertainty. All four articles suggest that hypothesis testing has contributed to progress in hydrology and is needed in the future. However, the procedure is usually not as systematic as the philosophy of science suggests. A greater emphasis on a creative reasoning process on the basis of clues and explorative analyses is therefore needed.

Epidemiology in the Era of Big Data

Science.gov (United States)

Mooney, Stephen J; Westreich, Daniel J; El-Sayed, Abdulrahman M

2015-01-01

Big Data has increasingly been promoted as a revolutionary development in the future of science, including epidemiology. However, the definition and implications of Big Data for epidemiology remain unclear. We here provide a working definition of Big Data predicated on the so-called ‘3 Vs’: variety, volume, and velocity. From this definition, we argue that Big Data has evolutionary and revolutionary implications for identifying and intervening on the determinants of population health. We suggest that as more sources of diverse data become publicly available, the ability to combine and refine these data to yield valid answers to epidemiologic questions will be invaluable. We conclude that, while epidemiology as practiced today will continue to be practiced in the Big Data future, a component of our field’s future value lies in integrating subject matter knowledge with increased technical savvy. Our training programs and our visions for future public health interventions should reflect this future. PMID:25756221

Lessons from sea louse and salmon epidemiology.

Science.gov (United States)

Groner, Maya L; Rogers, Luke A; Bateman, Andrew W; Connors, Brendan M; Frazer, L Neil; Godwin, Sean C; Krkošek, Martin; Lewis, Mark A; Peacock, Stephanie J; Rees, Erin E; Revie, Crawford W; Schlägel, Ulrike E

2016-03-05

Effective disease management can benefit from mathematical models that identify drivers of epidemiological change and guide decision-making. This is well illustrated in the host-parasite system of sea lice and salmon, which has been modelled extensively due to the economic costs associated with sea louse infections on salmon farms and the conservation concerns associated with sea louse infections on wild salmon. Consequently, a rich modelling literature devoted to sea louse and salmon epidemiology has been developed. We provide a synthesis of the mathematical and statistical models that have been used to study the epidemiology of sea lice and salmon. These studies span both conceptual and tactical models to quantify the effects of infections on host populations and communities, describe and predict patterns of transmission and dispersal, and guide evidence-based management of wild and farmed salmon. As aquaculture production continues to increase, advances made in modelling sea louse and salmon epidemiology should inform the sustainable management of marine resources. © 2016 The Author(s).

Antiaging therapy: a prospective hypothesis

Directory of Open Access Journals (Sweden)

Shahidi Bonjar MR

2015-01-01

Full Text Available Mohammad Rashid Shahidi Bonjar,1 Leyla Shahidi Bonjar2 1School of Dentistry, Kerman University of Medical Sciences, Kerman Iran; 2Department of Pharmacology, College of Pharmacy, Kerman University of Medical Sciences, Kerman, Iran Abstract: This hypothesis proposes a new prospective approach to slow the aging process in older humans. The hypothesis could lead to developing new treatments for age-related illnesses and help humans to live longer. This hypothesis has no previous documentation in scientific media and has no protocol. Scientists have presented evidence that systemic aging is influenced by peculiar molecules in the blood. Researchers at Albert Einstein College of Medicine, New York, and Harvard University in Cambridge discovered elevated titer of aging-related molecules (ARMs in blood, which trigger cascade of aging process in mice; they also indicated that the process can be reduced or even reversed. By inhibiting the production of ARMs, they could reduce age-related cognitive and physical declines. The present hypothesis offers a new approach to translate these findings into medical treatment: extracorporeal adjustment of ARMs would lead to slower rates of aging. A prospective “antiaging blood filtration column” (AABFC is a nanotechnological device that would fulfill the central role in this approach. An AABFC would set a near-youth homeostatic titer of ARMs in the blood. In this regard, the AABFC immobilizes ARMs from the blood while blood passes through the column. The AABFC harbors antibodies against ARMs. ARM antibodies would be conjugated irreversibly to ARMs on contact surfaces of the reaction platforms inside the AABFC till near-youth homeostasis is attained. The treatment is performed with the aid of a blood-circulating pump. Similar to a renal dialysis machine, blood would circulate from the body to the AABFC and from there back to the body in a closed circuit until ARMs were sufficiently depleted from the blood. The

Public Health Education: Teaching Epidemiology in High School Classrooms.

Science.gov (United States)

D'Agostino, Emily

2018-03-01

Epidemiology instruction has expanded at the undergraduate level in part because it increases student critical thinking and scientific literacy, promotes students' perception of public health as both practical and relevant, and empowers students as independent, lifelong learners. Why then are more high schools not adopting epidemiology as a course requirement for students? Although prior iterations of high school epidemiology courses are noteworthy for incorporating active and participatory learning, embedding them into existing and continually shifting curricula is challenging and time-consuming, especially for teachers not trained in the field. It also may be argued that currently available epidemiology teaching resources emphasize content rather than thinking skills and therefore do not optimally promote students' personal engagement with, and in-depth understanding of, the mission and goals of public health. I propose a new framework for high school epidemiology that draws from progressive education ideology, including three critical elements: empowerment, authenticity, and transfer. I provide multiple examples to show how this framework has been used across a wide array of settings to hone epidemiology thinking skills in high school students.

Epidemiology of Gout

Science.gov (United States)

Choi, Hyon

2014-01-01

Synopsis Gout is the most prevalent inflammatory arthritis in men. The findings of several epidemiological studies from a diverse range of countries suggest that the prevalence of gout has risen over the last few decades. Whilst incidence data are scarce, data from the US suggests that the incidence of gout is also rising. Evidence from prospective epidemiological studies has confirmed dietary factors (animal purines, alcohol and fructose), obesity, the metabolic syndrome, hypertension, diuretic use, and chronic kidney disease as clinically relevant risk factors for hyperuricemia and gout. Low-fat dairy products, coffee, and vitamin C appear to have a protective effect. Further prospective studies are required to examine other proposed risk factors for hyperuricaemia and gout such as the use of β-blockers and angiotension-II receptor antagonists (other than losartan), obstructive sleep apnoea, and osteoarthritis, and putative protective factors such as calcium-channel blockers and losartan. PMID:24703341

Partial information, market efficiency, and anomalous continuous phase transition

International Nuclear Information System (INIS)

Yang, Guang; Zheng, Wenzhi; Huang, Jiping

2014-01-01

It is a common belief in economics and social science that if there is more information available for agents to gather in a human system, the system can become more efficient. The belief can be easily understood according to the well-known efficient market hypothesis. In this work, we attempt to challenge this belief by investigating a complex adaptive system, which is modeled by a market-directed resource-allocation game with a directed random network. We conduct a series of controlled human experiments in the laboratory to show the reliability of the model design. As a result, we find that even under a small information concentration, the system can still almost reach the optimal (balanced) state. Furthermore, the ensemble average of the system’s fluctuation level goes through a continuous phase transition. This behavior means that in the second phase if too much information is shared among agents, the system’s stability will be harmed instead, which differs from the belief mentioned above. Also, at the transition point, the ensemble fluctuations of the fluctuation level remain at a low value. This phenomenon is in contrast to the textbook knowledge about continuous phase transitions in traditional physical systems, namely, fluctuations will rise abnormally around a transition point since the correlation length becomes infinite. Thus, this work is of potential value to a variety of fields, such as physics, economics, complexity science, and artificial intelligence. (paper)

Partial information, market efficiency, and anomalous continuous phase transition

Science.gov (United States)

Yang, Guang; Zheng, Wenzhi; Huang, Jiping

2014-04-01

It is a common belief in economics and social science that if there is more information available for agents to gather in a human system, the system can become more efficient. The belief can be easily understood according to the well-known efficient market hypothesis. In this work, we attempt to challenge this belief by investigating a complex adaptive system, which is modeled by a market-directed resource-allocation game with a directed random network. We conduct a series of controlled human experiments in the laboratory to show the reliability of the model design. As a result, we find that even under a small information concentration, the system can still almost reach the optimal (balanced) state. Furthermore, the ensemble average of the system’s fluctuation level goes through a continuous phase transition. This behavior means that in the second phase if too much information is shared among agents, the system’s stability will be harmed instead, which differs from the belief mentioned above. Also, at the transition point, the ensemble fluctuations of the fluctuation level remain at a low value. This phenomenon is in contrast to the textbook knowledge about continuous phase transitions in traditional physical systems, namely, fluctuations will rise abnormally around a transition point since the correlation length becomes infinite. Thus, this work is of potential value to a variety of fields, such as physics, economics, complexity science, and artificial intelligence.

Geomagnetic fluctuations during a polarity transition

Science.gov (United States)

Audunsson, Haraldur; Levi, Shaul

1997-01-01

The extensive Roza Member of the Columbia River Basalt Group (Washington State) has intermediate paleomagnetic directions, bracketed by underlying normal and overlying reverse polarity flows. A consistent paleomagnetic direction was measured at 11 widely distributed outcrops; the average direction has a declination of 189° and an inclination of -5°, with greater variation in the inclination [Rietman, 1966]. In this study the Roza Member was sampled in two Pasco Basin drillcores, where it is a single cooling unit and its thickness exceeds 50 m. Excellent core recovery allowed uniform and dense sampling of the drillcores. During its protracted cooling, the Roza flow in the drillcores recorded part of a 15.5 Ma geomagnetic polarity transition. The inclination has symmetric, quasicyclic intraflow variation, while the declination is nearly constant, consistent with the results from the outcrops. Thermal models of the cooling flow provide the timing for remanence acquisition. The inclination is inferred to have progressed from 0° to -15° and back to -3°over a period of 15 to 60 years, at rates of 1.6° to 0.5°/yr. Because the geomagnetic intensity was probably weak during the transition, these apparently high rates of change are not significantly different from present-day secular variation. These results agree with the hypothesis that normal secular variation persists through geomagnetic transitions. The Iow-amplitude quasicyclical fluctuations of the field over tens of years, recorded by Roza, suggest that the geomagnetic field reverses in discrete steps, and that more than 15-60 years were required to complete this reversal.

Does Portuguese economy support crude oil conservation hypothesis?

International Nuclear Information System (INIS)

Bashiri Behmiri, Niaz; Pires Manso, José R.

2012-01-01

This paper examines cointegration relationships and Granger causality nexus in a trivariate framework among oil consumption, economic growth and international oil price in Portugal. For this purpose, we employ two Granger causality approaches: the Johansen cointegration test and vector error correction model (VECM) and the Toda–Yamamoto approaches. Cointegration test proves the existence of a long run equilibrium relationship among these variables and VECM and Toda–Yamamoto Granger causality tests indicate that there is bidirectional causality between crude oil consumption and economic growth (feed back hypothesis). Therefore, the Portuguese economy does not support crude oil conservation hypothesis. Consequently, policymakers should consider that implementing oil conservation and environmental policies may negatively impact on the Portuguese economic growth. - Highlights: ► We examine Granger causality among oil consumption, GDP and oil price in Portugal. ► VECM and Toda–Yamamoto tests found bidirectional causality among oil and GDP. ► Portuguese economy does not support the crude oil conservation hypothesis.

A comparator-hypothesis account of biased contingency detection.

Science.gov (United States)

Vadillo, Miguel A; Barberia, Itxaso

2018-02-12

Our ability to detect statistical dependencies between different events in the environment is strongly biased by the number of coincidences between them. Even when there is no true covariation between a cue and an outcome, if the marginal probability of either of them is high, people tend to perceive some degree of statistical contingency between both events. The present paper explores the ability of the Comparator Hypothesis to explain the general pattern of results observed in this literature. Our simulations show that this model can account for the biasing effects of the marginal probabilities of cues and outcomes. Furthermore, the overall fit of the Comparator Hypothesis to a sample of experimental conditions from previous studies is comparable to that of the popular Rescorla-Wagner model. These results should encourage researchers to further explore and put to the test the predictions of the Comparator Hypothesis in the domain of biased contingency detection. Copyright © 2018 Elsevier B.V. All rights reserved.

The European concerted action on air pollution epidemiology

Energy Technology Data Exchange (ETDEWEB)

Ackermann-Liebrich, U. [Basel Univ. (Switzerland). Inst. for Social and Preventive Medicine

1995-12-31

The European Concerted Action on Air Pollution Epidemiology was started in 1990 with the aim of bringing together European researchers in the field and improving research through collaboration and by preparing documents which would help to this end and by organizing workshops. A further aim was to stimulate cooperative research. Air pollution epidemiology investigates human effects of community air pollution by epidemiological methods. Epidemiology in general investigates the distribution and determinants of health-related states and events in populations. Diseases in which air pollution may play a significant role are mainly diseases of the respiratory system, for example chronic non-specific lung disease and lung cancer. Most diseases caused by air pollution can also be caused by other factors. Air pollution epidemiology is therefore specific in the expo variable (community air pollution) rather than in the type of health effects being studied. Air pollution epidemiology is beset with some specially challenging difficulties: ubiquitous exposure and as a consequence limited heterogeneity in exposure, low relative risks, few or specific health end points, and strong confounding. Further on the exposure-effect relationship is complicated by assumptions inherent to different study designs which relate to the exposure duration necessary to produce a certain health effect. In reports and workshops the concerted action tries to propose strategies to deal with these problems. (author)

The European concerted action on air pollution epidemiology

Energy Technology Data Exchange (ETDEWEB)

Ackermann-Liebrich, U [Basel Univ. (Switzerland). Inst. for Social and Preventive Medicine

1996-12-31

The European Concerted Action on Air Pollution Epidemiology was started in 1990 with the aim of bringing together European researchers in the field and improving research through collaboration and by preparing documents which would help to this end and by organizing workshops. A further aim was to stimulate cooperative research. Air pollution epidemiology investigates human effects of community air pollution by epidemiological methods. Epidemiology in general investigates the distribution and determinants of health-related states and events in populations. Diseases in which air pollution may play a significant role are mainly diseases of the respiratory system, for example chronic non-specific lung disease and lung cancer. Most diseases caused by air pollution can also be caused by other factors. Air pollution epidemiology is therefore specific in the expo variable (community air pollution) rather than in the type of health effects being studied. Air pollution epidemiology is beset with some specially challenging difficulties: ubiquitous exposure and as a consequence limited heterogeneity in exposure, low relative risks, few or specific health end points, and strong confounding. Further on the exposure-effect relationship is complicated by assumptions inherent to different study designs which relate to the exposure duration necessary to produce a certain health effect. In reports and workshops the concerted action tries to propose strategies to deal with these problems. (author)

The epidemiology of pneumococcal carriage and infections in Malaysia.

Science.gov (United States)

Le, Cheng-Foh; Jefferies, Johanna M; Yusof, Mohd Yasim Mohd; Sekaran, Shamala Devi; Clarke, Stuart C

2012-06-01

In Malaysia, various aspects of the epidemiology of pneumococcal carriage and disease remain largely unclear due to the lack of supporting data. Although a number of relevant studies have been documented, their individual discrete findings are not sufficient to inform experts on pneumococcal epidemiology at a national level. Therefore, in this review we aim to bring together and systematically evaluate the key information regarding pneumococcal disease epidemiology in Malaysia and provide a comprehensive overview of the data. Major aspects discussed include pneumococcal carriage, disease incidence and prevalence, age factors, invasiveness of pneumococci, serotypes, molecular epidemiology and antibiotic susceptibility. Penicillin resistance is increasingly prevalent and studies suggest that the majority of pneumococcal serotypes causing pneumococcal disease in Malaysia are covered by currently available conjugate vaccines. Continued surveillance is needed to provide a better understanding of pneumococcal epidemiology in Malaysia.

[Precision medicine: new opportunities and challenges for molecular epidemiology].

Science.gov (United States)

Song, Jing; Hu, Yonghua

2016-04-01

Since the completion of the Human Genome Project in 2003 and the announcement of the Precision Medicine Initiative by U.S. President Barack Obama in January 2015, human beings have initially completed the " three steps" of " genomics to biology, genomics to health as well as genomics to society". As a new inter-discipline, the emergence and development of precision medicine have relied on the support and promotion from biological science, basic medicine, clinical medicine, epidemiology, statistics, sociology and information science, etc. Meanwhile, molecular epidemiology is considered to be the core power to promote precision medical as a cross discipline of epidemiology and molecular biology. This article is based on the characteristics and research progress of medicine and molecular epidemiology respectively, focusing on the contribution and significance of molecular epidemiology to precision medicine, and exploring the possible opportunities and challenges in the future.

Ophthalmic epidemiology in Europe : the "European Eye Epidemiology" (E3) consortium

NARCIS (Netherlands)

Delcourt, Cecile; Korobelnik, Jean-Francois; Buitendijk, Gabrielle H. S.; Foster, Paul J.; Hammond, Christopher J.; Piermarocchi, Stefano; Peto, Tunde; Jansonius, Nomdo; Mirshahi, Alireza; Hogg, Ruth E.; Bretillon, Lionel; Topouzis, Fotis; Deak, Gabor; Grauslund, Jakob; Broe, Rebecca; Souied, Eric H.; Creuzot-Garcher, Catherine; Sahel, Jose; Daien, Vincent; Lehtimaki, Terho; Hense, Hans-Werner; Prokofyeva, Elena; Oexle, Konrad; Rahi, Jugnoo S.; Cumberland, Phillippa M.; Schmitz-Valckenberg, Steffen; Fauser, Sascha; Bertelsen, Geir; Hoyng, Carel; Bergen, Arthur; Silva, Rufino; Wolf, Sebastian; Lotery, Andrew; Chakravarthy, Usha; Fletcher, Astrid; Klaver, Caroline C. W.

The European Eye Epidemiology (E3) consortium is a recently formed consortium of 29 groups from 12 European countries. It already comprises 21 population-based studies and 20 other studies (case-control, cases only, randomized trials), providing ophthalmological data on approximately 170,000

Counselor Hypothesis Testing Strategies: The Role of Initial Impressions and Self-Schema.

Science.gov (United States)

Strohmer, Douglas C.; Chiodo, Anthony L.

1984-01-01

Presents two experiments concerning confirmatory bias in the way counselors collect data to test their hypotheses. Counselors were asked either to develop their own clinical hypothesis or were given a hypothesis to test. Confirmatory bias in hypothesis testing was not supported in either experiment. (JAC)

A Molecular–Structure Hypothesis

Directory of Open Access Journals (Sweden)

Jan C. A. Boeyens

2010-11-01

Full Text Available The self-similar symmetry that occurs between atomic nuclei, biological growth structures, the solar system, globular clusters and spiral galaxies suggests that a similar pattern should characterize atomic and molecular structures. This possibility is explored in terms of the current molecular structure-hypothesis and its extension into four-dimensional space-time. It is concluded that a quantum molecule only has structure in four dimensions and that classical (Newtonian structure, which occurs in three dimensions, cannot be simulated by quantum-chemical computation.

Testing the carotenoid trade-off hypothesis in the polychromatic Midas cichlid, Amphilophus citrinellus.

Science.gov (United States)

Lin, Susan M; Nieves-Puigdoller, Katherine; Brown, Alexandria C; McGraw, Kevin J; Clotfelter, Ethan D

2010-01-01

Many animals use carotenoid pigments derived from their diet for coloration and immunity. The carotenoid trade-off hypothesis predicts that, under conditions of carotenoid scarcity, individuals may be forced to allocate limited carotenoids to either coloration or immunity. In polychromatic species, the pattern of allocation may differ among individuals. We tested the carotenoid trade-off hypothesis in the Midas cichlid, Amphilophus citrinellus, a species with two ontogenetic color morphs, barred and gold, the latter of which is the result of carotenoid expression. We performed a diet-supplementation experiment in which cichlids of both color morphs were assigned to one of two diet treatments that differed only in carotenoid content (beta-carotene, lutein, and zeaxanthin). We measured integument color using spectrometry, quantified carotenoid concentrations in tissue and plasma, and assessed innate immunity using lysozyme activity and alternative complement pathway assays. In both color morphs, dietary carotenoid supplementation elevated plasma carotenoid circulation but failed to affect skin coloration. Consistent with observable differences in integument coloration, we found that gold fish sequestered more carotenoids in skin tissue than barred fish, but barred fish had higher concentrations of carotenoids in plasma than gold fish. Neither measure of innate immunity differed between gold and barred fish, or as a function of dietary carotenoid supplementation. Lysozyme activity, but not complement activity, was strongly affected by body condition. Our data show that a diet low in carotenoids is sufficient to maintain both coloration and innate immunity in Midas cichlids. Our data also suggest that the developmental transition from the barred to gold morph is not accompanied by a decrease in innate immunity in this species.

Modeling inflation uncertainty in transition economies: The case of Russia and the former Soviet Republics

Directory of Open Access Journals (Sweden)

Erkam Serkan

2008-01-01

Full Text Available This study investigates the linkage between inflation and inflation uncertainty in seven transitional economies (Armenia, Azerbaijan, Georgia, Kazakhstan, the Kyrgyz Republic, the Russian Federation and the Ukraine which experienced hyper-inflation until the mid-1990s. This linkage is investigated in the ARCH modeling framework by using both conventional Granger noncausality testing and the Holmes-Hutton approach, which has significant small- and large-sample power advantages over the former. The results support the Friedman- Ball hypothesis in Azerbaijan, the Russian Federation and the Ukraine. The Cukierman-Meltzer hypothesis is favored in the Kyrgyz Republic and in the Russian Federation using a different model. In Azerbaijan, greater inflation uncertainty preceded lower rates of inflation, indicative of the strong monetary stabilization policies pursued in this economy.

The Current Status of the Disease Caused by Enterovirus 71 Infections: Epidemiology, Pathogenesis, Molecular Epidemiology, and Vaccine Development.

Science.gov (United States)

Chang, Ping-Chin; Chen, Shou-Chien; Chen, Kow-Tong

2016-09-09

Enterovirus 71 (EV71) infections have a major public health impact in the Asia-Pacific region. We reviewed the epidemiology, pathogenesis, and molecular epidemiology of EV71 infection as well as EV71 vaccine development. Previous studies were found using the search terms "enterovirus 71" and "epidemiology" or "pathogenesis" or "molecular epidemiology" or "vaccine" in Medline and PubMed. Articles that were not published in the English language, manuscripts without an abstract, and opinion articles were excluded from the review. The reported epidemiology of cases caused by EV71 infection varied from country to country; seasonal variations in incidence were observed. Most cases of EV71 infection that resulted in hospitalization for complications occurred in children less than five years old. The brainstem was the most likely major target of EV71 infection. The emergence of the EV71 epidemic in the Asia-Pacific region has been associated with the circulation of different genetic lineages (genotypes B3, B4, C1, C2, and C4) that appear to be undergoing rapid evolutionary changes. The relationship between the gene structure of the EV71 virus and the factors that ensure its survival, circulation, and evasion of immunity is still unknown. EV71 infection has emerged as an important global public health problem. Vaccine development, including the development of inactivated whole-virus live attenuated, subviral particles, and DNA vaccines, has been progressing.

Influence of confining prestress on the transition from interface defeat to penetration in ceramic targets

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Patrik Lundberg

2016-06-01

Full Text Available Replica scaled impact experiments with unconfined ceramic targets have shown that the transition velocity, i.e., the impact velocity at which interface defeat ceases and ceramic penetration occurs, decreased as the length scale increased. A possible explanation of how this scale effect is related to the formation of a cone crack in the ceramic has been presented by the authors in an earlier paper. Here, the influence of confinement and prestress on cone cracking and transition velocity is investigated. The hypothesis is that prestress will suppress the formation and growth of the cone crack by lowering the driving stress. A set of impact experiments has been performed in which the transition velocity for four different levels of prestress has been determined. The transition velocities as a function of the level of confining prestress is compared to an analytical model for the influence of prestress on the formation and extension of the cone crack in the ceramic material. Both experiments and model indicate that prestress has a strong influence on the transition from interface defeat to penetration, although the model underestimates the influence of prestress.

The catecholaminergic-cholinergic balance hypothesis of bipolar disorder revisited

Science.gov (United States)

van Enkhuizen, Jordy; Janowsky, David S; Olivier, Berend; Minassian, Arpi; Perry, William; Young, Jared W; Geyer, Mark A

2014-01-01

Bipolar disorder is a unique illness characterized by fluctuations between mood states of depression and mania. Originally, an adrenergic-cholinergic balance hypothesis was postulated to underlie these different affective states. In this review, we update this hypothesis with recent findings from human and animal studies, suggesting that a catecholaminergic-cholinergic hypothesis may be more relevant. Evidence from neuroimaging studies, neuropharmacological interventions, and genetic associations support the notion that increased cholinergic functioning underlies depression, whereas increased activations of the catecholamines (dopamine and norepinephrine) underlie mania. Elevated functional acetylcholine during depression may affect both muscarinic and nicotinic acetylcholine receptors in a compensatory fashion. Increased functional dopamine and norepinephrine during mania on the other hand may affect receptor expression and functioning of dopamine reuptake transporters. Despite increasing evidence supporting this hypothesis, a relationship between these two neurotransmitter systems that could explain cycling between states of depression and mania is missing. Future studies should focus on the influence of environmental stimuli and genetic susceptibilities that may affect the catecholaminergic-cholinergic balance underlying cycling between the affective states. Overall, observations from recent studies add important data to this revised balance theory of bipolar disorder, renewing interest in this field of research. PMID:25107282

The Method of Hypothesis in Plato's Philosophy

Directory of Open Access Journals (Sweden)

Malihe Aboie Mehrizi

2016-09-01

Full Text Available The article deals with the examination of method of hypothesis in Plato's philosophy. This method, respectively, will be examined in three dialogues of Meno, Phaedon and Republic in which it is explicitly indicated. It will be shown the process of change of Plato’s attitude towards the position and usage of the method of hypothesis in his realm of philosophy. In Meno, considering the geometry, Plato attempts to introduce a method that can be used in the realm of philosophy. But, ultimately in Republic, Plato’s special attention to the method and its importance in the philosophical investigations, leads him to revise it. Here, finally Plato introduces the particular method of philosophy, i.e., the dialectic

Exploring heterogeneous market hypothesis using realized volatility

Science.gov (United States)

Chin, Wen Cheong; Isa, Zaidi; Mohd Nor, Abu Hassan Shaari

2013-04-01

This study investigates the heterogeneous market hypothesis using high frequency data. The cascaded heterogeneous trading activities with different time durations are modelled by the heterogeneous autoregressive framework. The empirical study indicated the presence of long memory behaviour and predictability elements in the financial time series which supported heterogeneous market hypothesis. Besides the common sum-of-square intraday realized volatility, we also advocated two power variation realized volatilities in forecast evaluation and risk measurement in order to overcome the possible abrupt jumps during the credit crisis. Finally, the empirical results are used in determining the market risk using the value-at-risk approach. The findings of this study have implications for informationally market efficiency analysis, portfolio strategies and risk managements.

Neurodevelopmental and neurobehavioural effects of polybrominated and perfluorinated chemicals: a systematic review of the epidemiological literature using a quality assessment scheme.

Science.gov (United States)

Roth, N; Wilks, M F

2014-10-15

Concerns over effects of halogenated persistent environmental contaminants on the developing brain have been expressed for many years, and human biomonitoring has confirmed that low-level, prenatal and/or postnatal exposure of children to these chemicals is ubiquitous. Over the last decade there have been increasing reports in the epidemiological literature of the potential association of exposure to polybromo diphenylethers (PBDEs) and perfluorinated chemicals (PFCs) with neurodevelopmental and/or neurobehavioural effects in infants and children, such as adverse birth outcomes, cognitive deficits, developmental delay and attention deficit hyperactivity disorders (ADHD). However, direct evidence from epidemiology studies has been limited and contradictory. Given the general lack of comparability across studies in terms of design, conduct, methodology and reporting, we developed a checklist-type quality assessment scheme based on the STROBE guidelines and the proposed HONEES criteria, and conducted a systematic review of the epidemiological peer-reviewed literature published since 2006 on neurodevelopmental and/or neurobehavioural effects following prenatal and postnatal exposure to PBDEs and PFCs. We rated 7 of the 18 studies that met our inclusion criteria as being of high quality, 7 of moderate quality and 4 of low quality. Frequently observed shortcomings were the lack of consideration of confounding factors; uncertainties regarding exposure characterization; inadequate sample size; the lack of a clear dose-response; and the representativeness/generalizability of the results. Collectively, the epidemiological evidence does currently not support a strong causal association between PBDEs and PFCs and adverse neurodevelopmental and neurobehavioural outcomes in infants and children. However, despite their limitations, the studies raise questions that require further investigation through hypothesis-driven studies using more harmonized study designs and methodologies

The potential for oxytocin (OT) to prevent breast cancer: a hypothesis.

Science.gov (United States)

Murrell, T G

1995-08-01

This hypothesis proposes that carcinogens in the breast are generated by the action of superoxide free radicals released when acinal gland distension, under the influence of unopposed prolactin, causes microvessel ischaemia. Inadequate nipple care in the at-risk years leads to ductal obstruction preventing the elimination of carcinogens from the breast. The regular production of oxytocin (OT) from nipple stimulation would cause contraction of the myoepithelial cells, relieving acinal gland distension and aiding the active elimination of carcinogenic fluid from the breast. Mechanical breast pump stimulation causes an increase in plasma OT levels in the luteal but not in the follicular phase of the menstrual cycle. OT production upon nipple stimulation in the luteal phase of premenopausal, non-lactating women may be protective against the high rates of mitotic breast cell division noted at this time via the potential to block the effect of oestrogen. The epidemiology of breast cancer suggests that lengthy lactation time is beneficial. Sexual activity in nulliparous women also protects and OT levels have been shown to rise with orgasm in women and in men. OT systems in the brain are intricately linked to oestrogen and progesterone levels, and it is possible that these hormones may modify the OT secretory response both centrally and through an effect on the sensitivity of the breast. OT production with nipple care and in sex and lactation, and the reduction in cycling ovarian hormones that occurs with pregnancy, may all be important preventative factors in the development of breast cancer both pre- and post-menopausally.

Simultaneity modeling analysis of the environmental Kuznets curve hypothesis

International Nuclear Information System (INIS)

Ben Youssef, Adel; Hammoudeh, Shawkat; Omri, Anis

2016-01-01

The environmental Kuznets curve (EKC) hypothesis has been recognized in the environmental economics literature since the 1990's. Various statistical tests have been used on time series, cross section and panel data related to single and groups of countries to validate this hypothesis. In the literature, the validation has always been conducted by using a single equation. However, since both the environment and income variables are endogenous, the estimation of a single equation model when simultaneity exists produces inconsistent and biased estimates. Therefore, we formulate simultaneous two-equation models to investigate the EKC hypothesis for fifty-six countries, using annual panel data from 1990 to 2012, with the end year is determined by data availability for the panel. To make the panel data analysis more homogeneous, we investigate this issue for a three income-based panels (namely, high-, middle-, and low-income panels) given several explanatory variables. Our results indicate that there exists a bidirectional causality between economic growth and pollution emissions in the overall panels. We also find that the relationship is nonlinear and has an inverted U-shape for all the considered panels. Policy implications are provided. - Highlights: • We have given a new look for the validity of the EKC hypothesis. • We formulate two-simultaneous equation models to validate this hypothesis for fifty-six countries. • We find a bidirectional causality between economic growth and pollution emissions. • We also discover an inverted U-shaped between environmental degradation and economic growth. • This relationship varies at different stages of economic development.

Dopamine and reward: the anhedonia hypothesis 30 years on.

Science.gov (United States)

Wise, Roy A

2008-10-01

The anhedonia hypothesis--that brain dopamine plays a critical role in the subjective pleasure associated with positive rewards--was intended to draw the attention of psychiatrists to the growing evidence that dopamine plays a critical role in the objective reinforcement and incentive motivation associated with food and water, brain stimulation reward, and psychomotor stimulant and opiate reward. The hypothesis called to attention the apparent paradox that neuroleptics, drugs used to treat a condition involving anhedonia (schizophrenia), attenuated in laboratory animals the positive reinforcement that we normally associate with pleasure. The hypothesis held only brief interest for psychiatrists, who pointed out that the animal studies reflected acute actions of neuroleptics whereas the treatment of schizophrenia appears to result from neuroadaptations to chronic neuroleptic administration, and that it is the positive symptoms of schizophrenia that neuroleptics alleviate, rather than the negative symptoms that include anhedonia. Perhaps for these reasons, the hypothesis has had minimal impact in the psychiatric literature. Despite its limited heuristic value for the understanding of schizophrenia, however, the anhedonia hypothesis has had major impact on biological theories of reinforcement, motivation, and addiction. Brain dopamine plays a very important role in reinforcement of response habits, conditioned preferences, and synaptic plasticity in cellular models of learning and memory. The notion that dopamine plays a dominant role in reinforcement is fundamental to the psychomotor stimulant theory of addiction, to most neuroadaptation theories of addiction, and to current theories of conditioned reinforcement and reward prediction. Properly understood, it is also fundamental to recent theories of incentive motivation.

Adipocytes Promote B16BL6 Melanoma Cell Invasion and the Epithelial-to-Mesenchymal Transition

OpenAIRE

Kushiro, Kyoko; Chu, Randy A.; Verma, Akanksha; Núñez, Nomelí P.

2011-01-01

Metastatic melanoma is one of the most deadly and evasive types of cancer. On average, cancer patients with metastatic melanoma survive only 6–9 months after diagnosis. Epidemiological and animal studies suggest that obesity increases the metastatic ability of malignant melanoma, though the mechanism is not known. In the present studies, we assessed the ability of 3T3L1 adipocytes to modulate B16BL6 melanoma cell invasion and the Epithelial-to-Mesenchymal Transition (EMT). For this purpose, w...

A test of the orthographic recoding hypothesis

Science.gov (United States)

Gaygen, Daniel E.

2003-04-01

The Orthographic Recoding Hypothesis [D. E. Gaygen and P. A. Luce, Percept. Psychophys. 60, 465-483 (1998)] was tested. According to this hypothesis, listeners recognize spoken words heard for the first time by mapping them onto stored representations of the orthographic forms of the words. Listeners have a stable orthographic representation of words, but no phonological representation, when those words have been read frequently but never heard or spoken. Such may be the case for low frequency words such as jargon. Three experiments using visually and auditorily presented nonword stimuli tested this hypothesis. The first two experiments were explicit tests of memory (old-new tests) for words presented visually. In the first experiment, the recognition of auditorily presented nonwords was facilitated when they previously appeared on a visually presented list. The second experiment was similar, but included a concurrent articulation task during a visual word list presentation, thus preventing covert rehearsal of the nonwords. The results were similar to the first experiment. The third experiment was an indirect test of memory (auditory lexical decision task) for visually presented nonwords. Auditorily presented nonwords were identified as nonwords significantly more slowly if they had previously appeared on the visually presented list accompanied by a concurrent articulation task.

Epidemiology and ionizing radiations

International Nuclear Information System (INIS)

Bourguignon, M.; Masse, R.; Slama, R.; Spira, A.; Timarche, M.; Laurier, D.; Billon, S.; Rogel, A.; Telle Lamberton, M.; Catelinois, O.; Thierry, I.; Grosche, B.; Ron, E.; Vathaire, F. de; Cherie Challine, L.; Donadieu, J.; Pirard, Ph.; Bloch, J.; Setbon, M.

2004-01-01

The ionizing radiations have effects on living being. The determinist effects appear since a threshold of absorbed dose of radiation is reached. In return, the stochastic effects of ionizing radiations are these ones whom apparition cannot be described except in terms of probabilities. They are in one hand, cancers and leukemia, on the other hand, lesions of the genome potentially transmissible to the descendants. That is why epidemiology, defined by specialists as the science that studies the frequency and distribution of illness in time and space, the contribution of factors that determine this frequency and this distribution among human populations. This issue gathers and synthesizes the knowledge and examines the difficulties of methodologies. It allows to give its true place to epidemiology. (N.C.)

Population health and status of epidemiology: WHO European Region I.

Science.gov (United States)

Rahu, Mati; Vlassov, Vasiliy V; Pega, Frank; Andreeva, Tatiana; Ay, Pinar; Baburin, Aleksei; Bencko, Vladimír; Csépe, Péter; Gebska-Kuczerowska, Anita; Ondrusová, Martina; Ribak, Joseph

2013-06-01

This article of the International Epidemiological Association commissioned paper series stocktakes the population health and status of epidemiology in 21 of the 53 countries of the WHO European Region. By United Nations geographical classification, these countries belong to Eastern Europe, Western Asia and South-Central Asia. Published data were used to describe population health indicators and risk factors. Epidemiological training and research was assessed based on author knowledge, information searches and E-mail survey of experts. Bibliometric analyses determined epidemiological publication outputs. Between-country differences in life expectancy, amount and profile of disease burden and prevalence of risk factors are marked. Epidemiological training is affected by ongoing structural reforms of educational systems. Training is advanced in Israel and several Eastern European countries. Epidemiological research is mainly university-based in most countries, but predominantly conducted by governmental research institutes in several countries of the former Soviet Union. Funding is generally external and limited, partially due to competition from and prioritization of biomedical research. Multiple relevant professional societies exist, especially in Poland, the Czech Republic and Hungary. Few of the region's 39 epidemiological academic journals have international currency. The number of epidemiological publications per population is highest for Israel and lowest for South-Central Asian countries. Epidemiological capacity will continue to be heterogeneous across the region and depend more on countries' individual historical, social, political and economic conditions and contexts than their epidemiologists' successive efforts. National and international research funding, and within- and between-country collaborations should be enhanced, especially for South-Central Asian countries.

Diagnostic Hypothesis Generation and Human Judgment

Science.gov (United States)

Thomas, Rick P.; Dougherty, Michael R.; Sprenger, Amber M.; Harbison, J. Isaiah

2008-01-01

Diagnostic hypothesis-generation processes are ubiquitous in human reasoning. For example, clinicians generate disease hypotheses to explain symptoms and help guide treatment, auditors generate hypotheses for identifying sources of accounting errors, and laypeople generate hypotheses to explain patterns of information (i.e., data) in the…

Random walk theory and exchange rate dynamics in transition economies

Directory of Open Access Journals (Sweden)

Gradojević Nikola

2010-01-01

Full Text Available This paper investigates the validity of the random walk theory in the Euro-Serbian dinar exchange rate market. We apply Andrew Lo and Archie MacKinlay's (1988 conventional variance ratio test and Jonathan Wright's (2000 non-parametric ranks and signs based variance ratio tests to the daily Euro/Serbian dinar exchange rate returns using the data from January 2005 - December 2008. Both types of variance ratio tests overwhelmingly reject the random walk hypothesis over the data span. To assess the robustness of our findings, we examine the forecasting performance of a non-linear, nonparametric model in the spirit of Francis Diebold and James Nason (1990 and find that it is able to significantly improve upon the random walk model, thus confirming the existence of foreign exchange market imperfections in a small transition economy such as Serbia. In the last part of the paper, we conduct a comparative study on how our results relate to those of other transition economies in the region.

HCO+ Detection of Dust-depleted Gas in the Inner Hole of the LkCa 15 Pre-transitional Disk

NARCIS (Netherlands)

Drabek-Maunder, E.; Mohanty, S.; Greaves, J.; Kamp, I.; Meijerink, R.; Spaans, M.; Thi, W. -F; Woitke, P.

2016-01-01

LkCa 15 is an extensively studied star in the Taurus region, known for its pre-transitional disk with a large inner cavity in the dust continuum and normal gas accretion rate. The most popular hypothesis to explain the LkCa 15 data invokes one or more planets to carve out the inner cavity, while gas

Epidemiological studies of cognitive impairment and dementia across Eastern and Middle European countries (epidemiology of dementia in Eastern and Middle European Countries).

Science.gov (United States)

Kiejna, A; Frydecka, D; Adamowski, T; Bickel, H; Reynish, E; Prince, M; Caracciolo, B; Fratiglioni, L; Georges, J

2011-02-01

To determine the availability and the consistency of prevalence findings of epidemiological studies on cognitive impairment and dementia conducted in Eastern and Middle Europe. We adopted a stepwise multimethod study approach consisting of iterative literature searches for epidemiological articles published between 1990 and 2006 and subsequent data analyses of published material, reanalyses of existing accessible epidemiological data sets and expert inquiries in Eastern and Middle European countries. Systematic computer-assisted searches used the keywords: "dementia", "Alzheimer", "cognitive impairment", "incidence", "prevalence", "epidemiology" in combination with the name of the relevant countries or "Europe" in English and Polish language. We supplemented the literature search with a review of the references in the articles that were identified during the initial search. We were able to find few regional and country-specific epidemiological studies of various kinds (population-based, cohort, cross-sectional studies) and conducted on different restricted population groups of patients (from neurological units, out-patients units, residential homes). No studies were identified from most of the countries taken under consideration and the ones we found were characterized by an immense diversity with a considerable degree of clinical and methodological variations. The few studies that there are suggest prevalence rates of dementia in Eastern Europe similar to those in Western Europe. There is strong need for epidemiological studies in Eastern and Middle Europe, as well as for greater coordination and standardization of methods to improve the quality and comparability of epidemiological data to determine the prevalences' rates of dementia in all the EU countries. Copyright © 2010 John Wiley & Sons, Ltd.

Epidemiology & Genomics Research Program

Science.gov (United States)

The Epidemiology and Genomics Research Program, in the National Cancer Institute's Division of Cancer Control and Population Sciences, funds research in human populations to understand the determinants of cancer occurrence and outcomes.

Epidemiology of burns

NARCIS (Netherlands)

Dokter, Jan

2016-01-01

The aim of this thesis is to understand the epidemiology, treatment and outcomes of specialized burn care in The Netherlands. This thesis is mainly based on historical data of the burn centre in Rotterdam from 1986, combined with historical data from the burn centres in Groningen and Beverwijk from

Sexual activity as a trigger of myocardial infarction. A case-crossover analysis in the Stockholm Heart Epidemiology Programme (SHEEP)

DEFF Research Database (Denmark)

Möller, J; Ahlbom, A; Hulting, J

2001-01-01

.9). CONCLUSIONS: The increased risk of myocardial infarction after sexual activity and the further increase in risk among the less physically fit support the hypothesis of causal triggering by sexual activity. However, the absolute risk per hour is very low, and exposure is relatively infrequent. Thus having sex......OBJECTIVE: To investigate sexual activity as a trigger of myocardial infarction and the potential effect modification of physical fitness. DESIGN: A case-crossover study nested in the Stockholm Heart Epidemiology Programme (SHEEP). SETTING: Stockholm County from April 1993 to December 1994...... once a week only increases the annual risk of myocardial infarction slightly. Counselling should focus on encouraging patients to live a physically active life and not on abstaining from sexual activity....

ADHD in the Arab World: A Review of Epidemiologic Studies

Science.gov (United States)

Farah, Lynn G.; Fayyad, John A.; Eapen, Valsamma; Cassir,Youmna; Salamoun, Mariana M.; Tabet, Caroline C.; Mneimneh, Zeina N.; Karam, Elie G.

2009-01-01

Objective: Epidemiological studies on psychiatric disorders are quite rare in the Arab World. This article reviews epidemiological studies on ADHD in all the Arab countries. Method: All epidemiological studies on ADHD conducted from 1966 through th present were reviewed. Samples were drawn from the general community, primary care clinical…

Biological fingerprint of high LET radiation. Brenner hypothesis

International Nuclear Information System (INIS)

Kodama, Yoshiaki; Awa, Akio; Nakamura, Nori

1997-01-01

Hypothesis by Brenner et al. (1994) that in chromosome aberrations in human peripheral lymphocytes induced by radiation exposure, F value (dicentrics/rings) differs dependently on the LET and can be a biomarker of high LET radiation like neutron and α-ray was reviewed and evaluated as follows. Radiation and chromosome aberrations; in this section, unstable aberrations like dicentric and rings (r) and stable ones like translocation and pericentric inversions were described. F value. Brenner hypothesis. Bauchinger's refutation. F value determined by FISH method; here, FISH is fluorescence in situ hybridization. F value in studies by author's Radiation Effect Research Facility. Frequency of chromosome aberration in A-bomb survivors and ESR (ESR: electron spin resonance). The cause for fluctuation of F values. The Brenner hypothesis could not be supported by studies by author's facility, suggesting that the rate of inter-chromosomal and intra-chromosomal exchange abnormalities can not be distinguishable by the radiation LET. This might be derived from the difference in detection technology of r rather than in LET. (K.H.)

The discovered preference hypothesis - an empirical test

DEFF Research Database (Denmark)

Lundhede, Thomas; Ladenburg, Jacob; Olsen, Søren Bøye

Using stated preference methods for valuation of non-market goods is known to be vulnerable to a range of biases. Some authors claim that these so-called anomalies in effect render the methods useless for the purpose. However, the Discovered Preference Hypothesis, as put forth by Plott [31], offers...... an nterpretation and explanation of biases which entails that the stated preference methods need not to be completely written off. In this paper we conduct a test for the validity and relevance of the DPH interpretation of biases. In a choice experiment concerning preferences for protection of Danish nature areas...... as respondents evaluate more and more choice sets. This finding supports the Discovered Preference Hypothesis interpretation and explanation of starting point bias....

Hypothesis testing of scientific Monte Carlo calculations

Science.gov (United States)

Wallerberger, Markus; Gull, Emanuel

2017-11-01

The steadily increasing size of scientific Monte Carlo simulations and the desire for robust, correct, and reproducible results necessitates rigorous testing procedures for scientific simulations in order to detect numerical problems and programming bugs. However, the testing paradigms developed for deterministic algorithms have proven to be ill suited for stochastic algorithms. In this paper we demonstrate explicitly how the technique of statistical hypothesis testing, which is in wide use in other fields of science, can be used to devise automatic and reliable tests for Monte Carlo methods, and we show that these tests are able to detect some of the common problems encountered in stochastic scientific simulations. We argue that hypothesis testing should become part of the standard testing toolkit for scientific simulations.

The Twin Deficits Hypothesis: An Empirical Analysis for Tanzania

Directory of Open Access Journals (Sweden)

Manamba Epaphra

2017-09-01

Full Text Available This paper examines the relationship between current account and government budget deficits in Tanzania. The paper tests the validity of the twin deficits hypothesis, using annual time series data for the 1966-2015 period. The paper is thought to be significant because the concept of the twin deficit hypothesis is fraught with controversy. Some researches support the hypothesis that there is a positive relationship between current account deficits and fiscal deficits in the economy while others do not. In this paper, the empirical tests fail to reject the twin deficits hypothesis, indicating that rising budget deficits put more strain on the current account deficits in Tanzania. Specifically, the Vector Error Correction Model results support the conventional theory of a positive relationship between fiscal and external balances, with a relatively high speed of adjustment toward the equilibrium position. This evidence is consistent with a small open economy. To address the problem that may result from this kind of relationship, appropriate policy variables for reducing budget deficits such as reduction in non-development expenditure, enhancement of domestic revenue collection and actively fight corruption and tax evasion should be adopted. The government should also target export oriented firms and encourage an import substitution industry by creating favorable business environments.

Worldwide Report, Epidemiology, No. 327

National Research Council Canada - National Science Library

1983-01-01

Partial Contents: Epidemiology, Human Diseases, Health, Malaria, AIDS, Homosexual Male, Medical Administration, Rabies, Tuberculosis, Encephalitis Statistics, Gastroenteritie, Mystery Diseases, Children, Epidemics...

Epidemiological and radio-biological studies in high background radiation areas of Kerala coast: implications in radiation protection science and human health

International Nuclear Information System (INIS)

Das, Birajalaxmi

2018-01-01

Till date, Linear No Threshold hypothesis (LNT) is well accepted in radiation protection science in spite of its limitations. However, dose response studies using multiple biological end points from high-background radiation areas have challenged the linearity. Radio-biological and epidemiological studies from high level natural radiation areas of Kerala coast showed non-linearity as well as efficient repair of DNA damage in HLNRA indicating that dose limits for public exposure needs to be revisited which may have implications in radiation protection science, human health and low dose radiation biology. However, further studies using high throughput approach is required to identify chronic radiation signatures in human population exposed to elevated level of natural background radiation

Cation dyshomeostasis and cardiomyocyte necrosis: the Fleckenstein hypothesis revisited

Science.gov (United States)

Borkowski, Brian J.; Cheema, Yaser; Shahbaz, Atta U.; Bhattacharya, Syamal K.; Weber, Karl T.

2011-01-01

An ongoing loss of cardiomyocytes to apoptotic and necrotic cell death pathways contributes to the progressive nature of heart failure. The pathophysiological origins of necrotic cell loss relate to the neurohormonal activation that accompanies acute and chronic stressor states and which includes effector hormones of the adrenergic nervous system. Fifty years ago, Albrecht Fleckenstein and coworkers hypothesized the hyperadrenergic state, which accompanies such stressors, causes cardiomyocyte necrosis based on catecholamine-initiated excessive intracellular Ca2+ accumulation (EICA), and mitochondrial Ca2+ overloading in particular, in which the ensuing dysfunction and structural degeneration of these organelles leads to necrosis. In recent years, two downstream factors have been identified which, together with EICA, constitute a signal–transducer–effector pathway: (i) mitochondria-based induction of oxidative stress, in which the rate of reactive oxygen metabolite generation exceeds their rate of detoxification by endogenous antioxidant defences; and (ii) the opening of the mitochondrial inner membrane permeability transition pore (mPTP) followed by organellar swelling and degeneration. The pathogenesis of stress-related cardiomyopathy syndromes is likely related to this pathway. Other factors which can account for cytotoxicity in stressor states include: hypokalaemia; ionized hypocalcaemia and hypomagnesaemia with resultant elevations in parathyroid hormone serving as a potent mediator of EICA; and hypozincaemia with hyposelenaemia, which compromise antioxidant defences. Herein, we revisit the Fleckenstein hypothesis of EICA in leading to cardiomyocyte necrosis and the central role played by mitochondria. PMID:21398641

Evolution of Motor Control: From Reflexes and Motor Programs to the Equilibrium-Point Hypothesis.

Science.gov (United States)

Latash, Mark L

2008-01-01

This brief review analyzes the evolution of motor control theories along two lines that emphasize active (motor programs) and reactive (reflexes) features of voluntary movements. It suggests that the only contemporary hypothesis that integrates both approaches in a fruitful way is the equilibrium-point hypothesis. Physical, physiological, and behavioral foundations of the EP-hypothesis are considered as well as relations between the EP-hypothesis and the recent developments of the notion of motor synergies. The paper ends with a brief review of the criticisms of the EP-hypothesis and challenges that the hypothesis faces at this time.

Cosmetic talc as a risk factor for pleural mesothelioma: a weight of evidence evaluation of the epidemiology.

Science.gov (United States)

Finley, Brent L; Benson, Stacey M; Marsh, Gary M

2017-03-01

Due to some historical (and inaccurate) reports that asbestos might be present in some cosmetic talc products, questions are occasionally raised regarding the potential pleural mesothelioma risks associated with cosmetic talc products. Our objective was to determine the incidence of pleural mesothelioma of individuals exposed to cosmetic talc. We conducted a systematic review of the epidemiological literature for cosmetic talc miners and millers and found three occupational cohort studies that evaluated pleural mesothelioma incidence in workers in Italy, Norway, France, and Austria. We conducted a second literature review to evaluate the incidence and mortality of pleural mesothelioma among patients who received talc pleurodesis treatments before 1965 and found retrospective clinical studies including over 300 patients with follow-up ranging from 14 to 40 years. There were no mesotheliomas reported in any of the cosmetic talc miner and miller cohorts. A pooled analysis of data from the cohort mortality studies indicated that four mesothelioma deaths would have been expected from the 90,022 person-years of observation, and this was associated with 84% and 67% statistical power to observe a 3-fold or 2.5-fold increase in pleural mesothelioma mortality, respectively. None of the patients who received talc pleurodesis treatments developed mesothelioma. We conclude that there is no epidemiological evidence to support the hypothesis that exposure to cosmetic talc is associated with the development of pleural mesothelioma.

Hispanic Young Males' Mental Health From Adolescence Through the Transition to Fatherhood.

Science.gov (United States)

Garfield, Craig F; Abbott, Collin; Rutsohn, Joshua; Penedo, Frank

2018-03-01

The objective of the current study was to examine the associations between the transition to fatherhood and depressive symptoms scores among Hispanic men. Using the sample of Hispanic men included in the National Longitudinal Study of Adolescent to Adult Health, depressive symptom scores were examined from 1994 to 2008. A "fatherhood-year" data set was created that included the men's Center for Epidemiologic Studies Depression Scale (CES-D) scores as well as residency status with the child. By regressing age-adjusted standardized depressive symptom scores, associations between mental health scores of Hispanic men and their transition to fatherhood were identified. Among the 1,715 Hispanic men, resident ( n = 502) and nonresident ( n = 99) Hispanic fathers reported an increase in depressive symptom scores (CES-D) during the first 5 years after entrance into fatherhood (β = 0.150, 95% CI [0.062, 0.239] and β = 0.153, 95% CI [0.034, 0.271], respectively) compared to non-fathers ( n = 1,114), representing an increase of 10% for resident fathers and a 15% for nonresident fathers. Hispanic non-fathers reported a decrease in depressive symptom scores (CES-D) during parallel ages. Hispanic fathers, regardless of residency status, reported increased depressive symptoms in the first 5 years after the transition into fatherhood, a period critical in child development.

Six paths for the future of social epidemiology.

Science.gov (United States)

Galea, Sandro; Link, Bruce G

2013-09-15

Social epidemiology is now an accepted part of the academic intellectual landscape. However, in many ways, social epidemiology also runs the risk of losing the identity that distinguished it as a field during its emergence. In the present article, we scan the strengths of social epidemiology to imagine paths forward that will make the field distinct and useful to the understanding of population health in future. We suggest 6 paths to such a future, each emerging from promising research trends in the field in which social epidemiologists can, and should, lead in coming years. Each of these paths contributes to the formation of distinct capacities that social epidemiologists can claim and use to elaborate or fill in gaps in the already strong history of social epidemiology. They present an opportunity for the field to build on its strengths and move forward while leading in new and critical areas in population health.

A Hypothesis: Life Initiated from Two Genes, as Deduced from the RNA World Hypothesis and the Characteristics of Life-Like Systems

Directory of Open Access Journals (Sweden)

Kunio Kawamura

2016-08-01

Full Text Available RNA played a central role in the emergence of the first life-like system on primitive Earth since RNA molecules contain both genetic information and catalytic activity. However, there are several drawbacks regarding the RNA world hypothesis. Here, I briefly discuss the feasibility of the RNA world hypothesis to deduce the RNA functions that are essential for forming a life-like system. At the same time, I have conducted a conceptual analysis of the characteristics of biosystems as a useful approach to deduce a realistic life-like system in relation to the definition of life. For instance, an RNA-based life-like system should possess enough stability to resist environmental perturbations, by developing a cell-like compartment, for instance. Here, a conceptual viewpoint is summarized to provide a realistic life-like system that is compatible with the primitive Earth environment and the capabilities of RNA molecules. According to the empirical and conceptual analysis, I propose the hypothesis that the first life-like system could have initiated from only two genes.

Dopamine and Reward: The Anhedonia Hypothesis 30 years on

OpenAIRE

Wise, Roy A.

2008-01-01

The anhedonia hypothesis – that brain dopamine plays a critical role in the subjective pleasure associated with positive rewards – was intended to draw the attention of psychiatrists to the growing evidence that dopamine plays a critical role in the objective reinforcement and incentive motivation associated with food and water, brain stimulation reward, and psychomotor stimulant and opiate reward. The hypothesis called to attention the apparent paradox that neuroleptics, drugs used to treat ...

Review series on helminths, immune modulation and the hygiene hypothesis: the broader implications of the hygiene hypothesis.

Science.gov (United States)

Rook, Graham A W

2009-01-01

Man has moved rapidly from the hunter-gatherer environment to the living conditions of the rich industrialized countries. The hygiene hypothesis suggests that the resulting changed and reduced pattern of exposure to microorganisms has led to disordered regulation of the immune system, and hence to increases in certain inflammatory disorders. The concept began with the allergic disorders, but there are now good reasons for extending it to autoimmunity, inflammatory bowel disease, neuroinflammatory disorders, atherosclerosis, depression associated with raised inflammatory cytokines, and some cancers. This review discusses these possibilities in the context of Darwinian medicine, which uses knowledge of evolution to cast light on human diseases. The Darwinian approach enables one to correctly identify some of the organisms that are important for the 'Hygiene' or 'Old Friends' hypothesis, and to point to the potential exploitation of these organisms or their components in novel types of prophylaxis with applications in several branches of medicine.

Examination of the embargo hypothesis as an explanation for the Great Silence

Science.gov (United States)

Deardorff, J. W.

1987-08-01

The embargo or quarantine hypothesis for explaining the 'Great Silence' is reviewed and found to be more plausible than the view that, at most, earth might expect to receive radio messages from some distant star. The latter hypothesis is shown to be compatible with extraterrestrial technologies only a few hundred years in advance of those on earth, whereas the embargo hypothesis more reasonably infers that they should be tens of thousands of years in advance and in control of any contact with humanity. Reasons why the embargo hypothesis has received insufficient attention are presented; they involve failure to allow for the application of both greatly advanced technology and high ethical values by maturing societies of extraterrestrial intelligence. The implication of the embargo hypothesis for space development is that planets already harboring diverse biota are ethically off-limits for exploitive colonization.

The equilibrium-point hypothesis--past, present and future.

Science.gov (United States)

Feldman, Anatol G; Levin, Mindy F

2009-01-01

This chapter is a brief account of fundamentals of the equilibrium-point hypothesis or more adequately called the threshold control theory (TCT). It also compares the TCT with other approaches to motor control. The basic notions of the TCT are reviewed with a major focus on solutions to the problems of multi-muscle and multi-degrees of freedom redundancy. The TCT incorporates cognitive aspects by explaining how neurons recognize that internal (neural) and external (environmental) events match each other. These aspects as well as how motor learning occurs are subjects of further development of the TCT hypothesis.

The evolution of competition in banking in a transition economy: an application of the Panzar-Rosse model to Armenia

Directory of Open Access Journals (Sweden)

Armenuhi Mkrtchyan

2005-06-01

Full Text Available The structure of the banking industry typically undergoes fundamental changes during the transition to a market economy. This research employs the method suggested by Panzar and Rosse (1987 to evaluate the empirical evidence on the evolution of competitive structure in the Armenian banking industry during its recent transition and on the possible forces—market power or efficiency/contestability—that underlie that evolution. The results point to monopolistic competition.The reduction of bank numbers and the simultaneous increase in concentration is accompanied by a decline in competition intensity, which supports the market-power hypothesis

High-Speed Imaging Analysis of Register Transitions in Classically and Jazz-Trained Male Voices.

Science.gov (United States)

Dippold, Sebastian; Voigt, Daniel; Richter, Bernhard; Echternach, Matthias

2015-01-01

Little data are available concerning register functions in different styles of singing such as classically or jazz-trained voices. Differences between registers seem to be much more audible in jazz singing than classical singing, and so we hypothesized that classically trained singers exhibit a smoother register transition, stemming from more regular vocal fold oscillation patterns. High-speed digital imaging (HSDI) was used for 19 male singers (10 jazz-trained singers, 9 classically trained) who performed a glissando from modal to falsetto register across the register transition. Vocal fold oscillation patterns were analyzed in terms of different parameters of regularity such as relative average perturbation (RAP), correlation dimension (D2) and shimmer. HSDI observations showed more regular vocal fold oscillation patterns during the register transition for the classically trained singers. Additionally, the RAP and D2 values were generally lower and more consistent for the classically trained singers compared to the jazz singers. However, intergroup comparisons showed no statistically significant differences. Some of our results may support the hypothesis that classically trained singers exhibit a smoother register transition from modal to falsetto register. © 2015 S. Karger AG, Basel.

Multi-hypothesis distributed stereo video coding

DEFF Research Database (Denmark)

Salmistraro, Matteo; Zamarin, Marco; Forchhammer, Søren

2013-01-01

for stereo sequences, exploiting an interpolated intra-view SI and two inter-view SIs. The quality of the SI has a major impact on the DVC Rate-Distortion (RD) performance. As the inter-view SIs individually present lower RD performance compared with the intra-view SI, we propose multi-hypothesis decoding...

Morbidity and Infant Development: A Hypothesis.

Science.gov (United States)

Pollitt, Ernesto

1983-01-01

Results of a study conducted in 14 villages of Sui Lin Township, Taiwan, suggest the hypothesis that, under conditions of extreme economic impoverishment and among children within populations where energy protein malnutrition is endemic, there is an inverse relationship between incidence of morbidity in infancy and measures of motor and mental…

The High-Density Lipoprotein Puzzle: Why Classic Epidemiology, Genetic Epidemiology, and Clinical Trials Conflict?

Science.gov (United States)

Rosenson, Robert S

2016-05-01

Classical epidemiology has established the incremental contribution of the high-density lipoprotein (HDL) cholesterol measure in the assessment of atherosclerotic cardiovascular disease risk; yet, genetic epidemiology does not support a causal relationship between HDL cholesterol and the future risk of myocardial infarction. Therapeutic interventions directed toward cholesterol loading of the HDL particle have been based on epidemiological studies that have established HDL cholesterol as a biomarker of atherosclerotic cardiovascular risk. However, therapeutic interventions such as niacin, cholesteryl ester transfer protein inhibitors increase HDL cholesterol in patients treated with statins, but have repeatedly failed to reduce cardiovascular events. Statin therapy interferes with ATP-binding cassette transporter-mediated macrophage cholesterol efflux via miR33 and thus may diminish certain HDL functional properties. Unraveling the HDL puzzle will require continued technical advances in the characterization and quantification of multiple HDL subclasses and their functional properties. Key mechanistic criteria for clinical outcomes trials with HDL-based therapies include formation of HDL subclasses that improve the efficiency of macrophage cholesterol efflux and compositional changes in the proteome and lipidome of the HDL particle that are associated with improved antioxidant and anti-inflammatory properties. These measures require validation in genetic studies and clinical trials of HDL-based therapies on the background of statins. © 2016 American Heart Association, Inc.

A Critique of One-Tailed Hypothesis Test Procedures in Business and Economics Statistics Textbooks.

Science.gov (United States)

Liu, Tung; Stone, Courtenay C.

1999-01-01

Surveys introductory business and economics statistics textbooks and finds that they differ over the best way to explain one-tailed hypothesis tests: the simple null-hypothesis approach or the composite null-hypothesis approach. Argues that the composite null-hypothesis approach contains methodological shortcomings that make it more difficult for…

Knox meets Cox: adapting epidemiological space-time statistics to demographic studies.

Science.gov (United States)

Schmertmann, Carl P; Assuçãon, Renato M; Potter, Joseph E

2010-08-01

Many important questions and theories in demography focus on changes over time, and on how those changes differ over geographic and social space. Space-time analysis has always been important in studying fertility transitions, for example. However demographers have seldom used formal statistical methods to describe and analyze time series of maps. One formal method, used widely in epidemiology, criminology, and public health, is Knox 's space-time interaction test. In this article, we discuss the potential of the Knox test in demographic research and note some possible pitfalls. We demonstrate how to use familiar proportional hazards models to adapt the Knox test for demographic applications. These adaptations allow for nonrepeatable events and for the incorporation of structural variables that change in space and time. We apply the modified test to data on the onset offertility decline in Brazil over 1960-2000 and show how the modified method can produce maps indicating where and when diffusion effects seem strongest, net of covariate effects.

The frequentist implications of optional stopping on Bayesian hypothesis tests.

Science.gov (United States)

Sanborn, Adam N; Hills, Thomas T

2014-04-01

Null hypothesis significance testing (NHST) is the most commonly used statistical methodology in psychology. The probability of achieving a value as extreme or more extreme than the statistic obtained from the data is evaluated, and if it is low enough, the null hypothesis is rejected. However, because common experimental practice often clashes with the assumptions underlying NHST, these calculated probabilities are often incorrect. Most commonly, experimenters use tests that assume that sample sizes are fixed in advance of data collection but then use the data to determine when to stop; in the limit, experimenters can use data monitoring to guarantee that the null hypothesis will be rejected. Bayesian hypothesis testing (BHT) provides a solution to these ills because the stopping rule used is irrelevant to the calculation of a Bayes factor. In addition, there are strong mathematical guarantees on the frequentist properties of BHT that are comforting for researchers concerned that stopping rules could influence the Bayes factors produced. Here, we show that these guaranteed bounds have limited scope and often do not apply in psychological research. Specifically, we quantitatively demonstrate the impact of optional stopping on the resulting Bayes factors in two common situations: (1) when the truth is a combination of the hypotheses, such as in a heterogeneous population, and (2) when a hypothesis is composite-taking multiple parameter values-such as the alternative hypothesis in a t-test. We found that, for these situations, while the Bayesian interpretation remains correct regardless of the stopping rule used, the choice of stopping rule can, in some situations, greatly increase the chance of experimenters finding evidence in the direction they desire. We suggest ways to control these frequentist implications of stopping rules on BHT.

Extraction of airway trees using multiple hypothesis tracking and template matching

DEFF Research Database (Denmark)

Raghavendra, Selvan; Petersen, Jens; Pedersen, Jesper Johannes Holst

2016-01-01

used in constructing a multiple hypothesis tree, which is then traversed to reach decisions. The proposed modifications remove the need for local thresholding of hypotheses as decisions are made entirely based on statistical comparisons involving the hypothesis tree. The results show improvements......Knowledge of airway tree morphology has important clinical applications in diagnosis of chronic obstructive pulmonary disease. We present an automatic tree extraction method based on multiple hypothesis tracking and template matching for this purpose and evaluate its performance on chest CT images...

Muon capture on Ni isotopes, projected QRPA, and CVC hypothesis

International Nuclear Information System (INIS)

Samana, Arturo R.; Sande, Danilo; Krmpotic, Francisco; Universidad Nacional de La Plata

2011-01-01

In recent years we have developed a novel formalism for the weak interaction processes, obtaining new expressions for the transition rates, which greatly facilitate numerical calculations, for both neutrino-nucleus reactions and muon capture, allowing us to use very large configuration spaces and to evaluate the quasielastic 12 C (ν, μ - ) 12 N cross section at energies of the order of 1 GeV, which are measured in the MiniBooNE experiment. Our formulation includes for the first time the consequences of the explicit violation of the conserved vector current (CVC) hypothesis by the Coulomb field. We have also shown that the particle number projection procedure within the quasiparticle random phase approximation (QRPA) is important in describing the exclusive (ground-state) properties of 12 B and 12 N as well as the muon capture rate and the neutrino nucleus cross section in 56 Fe. In this work, we analyze in a quantitative way the consequences of the CVC violation on the muon capture rates in Ni isotopes (for which are available the experimental data) using both the standard QRPA and the projected QRPA (PQRPA). The last one is the only RPA model that treats the Pauli Principle correctly, and we demonstrate that the number projection procedure is important not only for light nuclei but also for medium heavy ones that were studied here. (author)

Behavior of supercooled aqueous solutions stemming from hidden liquid-liquid transition in water.

Science.gov (United States)

Biddle, John W; Holten, Vincent; Anisimov, Mikhail A

2014-08-21

A popular hypothesis that explains the anomalies of supercooled water is the existence of a metastable liquid-liquid transition hidden below the line of homogeneous nucleation. If this transition exists and if it is terminated by a critical point, the addition of a solute should generate a line of liquid-liquid critical points emanating from the critical point of pure metastable water. We have analyzed thermodynamic consequences of this scenario. In particular, we consider the behavior of two systems, H2O-NaCl and H2O-glycerol. We find the behavior of the heat capacity in supercooled aqueous solutions of NaCl, as reported by Archer and Carter [J. Phys. Chem. B 104, 8563 (2000)], to be consistent with the presence of the metastable liquid-liquid transition. We elucidate the non-conserved nature of the order parameter (extent of "reaction" between two alternative structures of water) and the consequences of its coupling with conserved properties (density and concentration). We also show how the shape of the critical line in a solution controls the difference in concentration of the coexisting liquid phases.

Epidemiological characterization of oral cancer. Study Protocol.

Directory of Open Access Journals (Sweden)

Alejandra Fernández

2015-04-01

Full Text Available Oral cancer is a disease of high impact globally. It ranks as the sixth more frequent one among all types of cancer. In spite of being a widely known pathology and easy access to the diagnosis, the lack of epidemiological data reported in the last 10 years in Chile called attention to. At the global level, the World Health Organization (WHO has developed a project called “GLOBOCAN” in order to collect epidemiological data of the global cancer, between its data, highlights the high incidence and high rate of mortality in the male sex, parameter that shows tendency to replicate in both America and Chile. In consequence to these data, a narrative review of the literature concerning the epidemiological profile of the different forms of oral cancer in the past 15 years was done. The diagnosis of oral cancer crosses transversely the Dental Science, forcing us to establish triads of work between oral and maxillofacial surgeons, pathologists and dentists of the various specialties, so as to allow a timely research, appropriate biopsies and histopathological studies finishes with the purpose of, on the one hand, obtain timely and accurate diagnostics, in addition, maintaining the epidemiological indicators.

Diffusive dynamics during the high-to-low density transition in amorphous ice

Science.gov (United States)

Perakis, Fivos; Amann-Winkel, Katrin; Lehmkühler, Felix; Sprung, Michael; Mariedahl, Daniel; Sellberg, Jonas A.; Pathak, Harshad; Späh, Alexander; Cavalca, Filippo; Schlesinger, Daniel; Ricci, Alessandro; Jain, Avni; Massani, Bernhard; Aubree, Flora; Benmore, Chris J.; Loerting, Thomas; Grübel, Gerhard; Pettersson, Lars G. M.; Nilsson, Anders

2017-08-01

Water exists in high- and low-density amorphous ice forms (HDA and LDA), which could correspond to the glassy states of high- (HDL) and low-density liquid (LDL) in the metastable part of the phase diagram. However, the nature of both the glass transition and the high-to-low-density transition are debated and new experimental evidence is needed. Here we combine wide-angle X-ray scattering (WAXS) with X-ray photon-correlation spectroscopy (XPCS) in the small-angle X-ray scattering (SAXS) geometry to probe both the structural and dynamical properties during the high-to-low-density transition in amorphous ice at 1 bar. By analyzing the structure factor and the radial distribution function, the coexistence of two structurally distinct domains is observed at T = 125 K. XPCS probes the dynamics in momentum space, which in the SAXS geometry reflects structural relaxation on the nanometer length scale. The dynamics of HDA are characterized by a slow component with a large time constant, arising from viscoelastic relaxation and stress release from nanometer-sized heterogeneities. Above 110 K a faster, strongly temperature-dependent component appears, with momentum transfer dependence pointing toward nanoscale diffusion. This dynamical component slows down after transition into the low-density form at 130 K, but remains diffusive. The diffusive character of both the high- and low-density forms is discussed among different interpretations and the results are most consistent with the hypothesis of a liquid-liquid transition in the ultraviscous regime.

On the validity of Taylor's hypothesis for wall-bounded flows

International Nuclear Information System (INIS)

Piomelli, U.; Balint, J.; Wallace, J.M.

1989-01-01

The results of large eddy simulation (LES) of the Navier--Stokes equations are used to evaluate the validity of Taylor's hypothesis of frozen turbulence, which states that the time derivative of some instantaneous quantity is proportional to its derivative in the streamwise direction, for incompressible plane channel flow. Time and space derivatives in the streamwise direction of the velocity components are, in fact, found to be well correlated. Root-mean-square fluctuations of the terms in Taylor's hypothesis also support the validity of this hypothesis above the buffer layer. The good agreement between LES and experimental results indicates that errors in the evaluation of derivatives in the streamwise direction are due mostly to insufficient resolution

Ethics Guidelines in Environmental Epidemiology: Their Development and Challenges We Face.

Science.gov (United States)

Kramer, Shira; Soskolne, Colin L

2017-06-01

This review integrates historical developments and key events in bringing ethics into epidemiology in general and into environmental epidemiology in particular. The goal is to provide context for and discern among the various approaches and motivations that drive the need for ethical conduct in support of the public interest. The need for ethics guidelines in epidemiology is different from developments in other biomedical-related fields by virtue of its focus on populations rather than on individuals. The need for ethics guidelines in environmental epidemiology as a subspecialty of epidemiology stems from the larger scale of its mission than that of epidemiology per se. Ethics guidelines in the field of environmental epidemiology have been established. They articulate not only the profession's core values and mission, but more specifically, they address the environmental epidemiologist's obligations to the participants in research, to colleagues, and to employers. They are the product of consensus, scholarship, and diligent stewardship over several decades. The next challenge is ensuring their value and impact. The forces that support professional and institutional success, and the power of special interests, are the major threats to achieving the goals of ethical conduct and research for the public good. In environmental epidemiology, these threats have global implications.

El papel de la epidemiología en la investigación de los trastornos mentales The role of epidemiology in mental disorder research

Directory of Open Access Journals (Sweden)

Guilherme Borges

2004-10-01

Full Text Available Los trastornos mentales, incluyendo los trastornos del uso de sustancias, hacen ya parte del panorama epidemiológico de México y seguirán en el escenario nacional por las próximas décadas, incrementando incluso su presencia como causa de enfermedad, discapacidad y muerte en nuestro país. Por lo tanto, el manejo epidemiológico de estos problemas se hace urgente. Este trabajo busca plantear el campo de estudio de la epidemiología de los trastornos mentales y sus limitaciones, haciendo énfasis en los elementos comunes de ésta con otras áreas más tradicionales de la epidemiología y en las aportaciones particulares de este campo epidemiológico a la psiquiatría en general y a la epidemiología en particular. Planteamos a continuación los diseños y problemas más comunes en este campo de la epidemiología, su utilidad para acciones de prevención, y señalamos los retos que nos esperan en el futuro. Una característica distintiva de esta área es que los trastornos mentales se manifiestan en dos niveles, como conducta (por ejemplo, una conducta compulsiva de lavarse las manos y como elemento de la vida mental del sujeto (por ejemplo, el pensamiento obsesivo sobre las bacterias que se encuentran presentes en todos lados y que son una fuente constante de amenaza para algunos sujetos. Debido a esto, mucho de lo que sabemos sobre estos fenómenos proviene del autorreporte que el sujeto es capaz de hacer sobre sus sentimientos (introspección, ya sea en una conversación con un clínico entrenado o expresándolos al endosar reactivos en un cuestionario estandarizado. Otro aspecto importante a resaltar es la necesidad de hablar en plural al referirnos a los trastornos mentales. Este campo de la epidemiología presenta también un carácter particular, bifacético: por un lado, este es un problema en sí mismo, que produce sufrimiento y motiva la búsqueda de atención especializada, con manifestaciones clínicas particulares. Por otro lado

The Rwanda Field Epidemiology and Laboratory Training Program ...

African Journals Online (AJOL)

The Rwanda Field Epidemiology and Laboratory Training Program (RFELTP) is a 2-year public health leadership development training program that provides applied epidemiology and public health laboratory training while the trainees provide public health service to the Ministry of Health. RFELTP is hosted at the National ...

A critique of statistical hypothesis testing in clinical research

Directory of Open Access Journals (Sweden)

Somik Raha

2011-01-01

Full Text Available Many have documented the difficulty of using the current paradigm of Randomized Controlled Trials (RCTs to test and validate the effectiveness of alternative medical systems such as Ayurveda. This paper critiques the applicability of RCTs for all clinical knowledge-seeking endeavors, of which Ayurveda research is a part. This is done by examining statistical hypothesis testing, the underlying foundation of RCTs, from a practical and philosophical perspective. In the philosophical critique, the two main worldviews of probability are that of the Bayesian and the frequentist. The frequentist worldview is a special case of the Bayesian worldview requiring the unrealistic assumptions of knowing nothing about the universe and believing that all observations are unrelated to each other. Many have claimed that the first belief is necessary for science, and this claim is debunked by comparing variations in learning with different prior beliefs. Moving beyond the Bayesian and frequentist worldviews, the notion of hypothesis testing itself is challenged on the grounds that a hypothesis is an unclear distinction, and assigning a probability on an unclear distinction is an exercise that does not lead to clarity of action. This critique is of the theory itself and not any particular application of statistical hypothesis testing. A decision-making frame is proposed as a way of both addressing this critique and transcending ideological debates on probability. An example of a Bayesian decision-making approach is shown as an alternative to statistical hypothesis testing, utilizing data from a past clinical trial that studied the effect of Aspirin on heart attacks in a sample population of doctors. As a big reason for the prevalence of RCTs in academia is legislation requiring it, the ethics of legislating the use of statistical methods for clinical research is also examined.

Geographic variation in chin shape challenges the universal facial attractiveness hypothesis.

Directory of Open Access Journals (Sweden)

Zaneta M Thayer

Full Text Available The universal facial attractiveness (UFA hypothesis proposes that some facial features are universally preferred because they are reliable signals of mate quality. The primary evidence for this hypothesis comes from cross-cultural studies of perceived attractiveness. However, these studies do not directly address patterns of morphological variation at the population level. An unanswered question is therefore: Are universally preferred facial phenotypes geographically invariant, as the UFA hypothesis implies? The purpose of our study is to evaluate this often overlooked aspect of the UFA hypothesis by examining patterns of geographic variation in chin shape. We collected symphyseal outlines from 180 recent human mandibles (90 male, 90 female representing nine geographic regions. Elliptical Fourier functions analysis was used to quantify chin shape, and principle components analysis was used to compute shape descriptors. In contrast to the expectations of the UFA hypothesis, we found significant geographic differences in male and female chin shape. These findings are consistent with region-specific sexual selection and/or random genetic drift, but not universal sexual selection. We recommend that future studies of facial attractiveness take into consideration patterns of morphological variation within and between diverse human populations.

Commentary: Epidemiology in the era of big data.

Science.gov (United States)

Mooney, Stephen J; Westreich, Daniel J; El-Sayed, Abdulrahman M

2015-05-01

Big Data has increasingly been promoted as a revolutionary development in the future of science, including epidemiology. However, the definition and implications of Big Data for epidemiology remain unclear. We here provide a working definition of Big Data predicated on the so-called "three V's": variety, volume, and velocity. From this definition, we argue that Big Data has evolutionary and revolutionary implications for identifying and intervening on the determinants of population health. We suggest that as more sources of diverse data become publicly available, the ability to combine and refine these data to yield valid answers to epidemiologic questions will be invaluable. We conclude that while epidemiology as practiced today will continue to be practiced in the Big Data future, a component of our field's future value lies in integrating subject matter knowledge with increased technical savvy. Our training programs and our visions for future public health interventions should reflect this future.

GHG emissions, GDP growth and the Kyoto Protocol: A revisit of Environmental Kuznets Curve hypothesis

Energy Technology Data Exchange (ETDEWEB)

Huang, Wei Ming; Lee, Grace W.M. [Graduate Institute of Environmental Engineering, National Taiwan University, 71, Chou-Shan Road, Taipei 106 (China); Wu, Chih Cheng [Energy and Air Pollution Control Section, New Materials R and D Department, China Steel Corporation, 1, Chung-Kang Road, Siaogang District, Kaohsiung 81233 (China)

2008-01-15

The Kyoto Protocol attempts through political negotiations to guide participating industrialized countries' greenhouse gas (GHG) emissions from a positive growing trend, to reach a peak point (or turning point), and then be reduced to a negative growth. That means the relationship between decreasing GHG emissions and economic growth may be described by an inverted-U curve (or called a bell-shaped curve), which is consistent with the concept of the Environmental Kuznets Curve (EKC) hypothesis. This research observed that the economic development and GHG emissions in Economies in Transition (EITs) exhibit a hockey-stick curve trend (or called quasi-L-shape curve), that also generates a lot of 'hot air' which is significant to the implementation of the Kyoto Protocol. In addition, through the analysis of single-country time series data and GDP data, this research demonstrated that statistical data for most of the Annex II countries do not possess evidence that supports the EKC hypothesis for GHG emissions. The results from this study also indicated that the 38 industrialized countries are unable to meet their targets under the Kyoto Protocol within the specified time period, which are probably caused by the econometric method's inability to predict accurately the extents and development of innovative technologies and Clean Development Mechanism (CDM) projects. If the international community truly wants to reduce the GHG emissions, the effectiveness of the existing international framework for emissions reduction needs to be reconsidered seriously, and the global cooperation mechanism also needs to be greatly enhanced. (author)

GHG emissions, GDP growth and the Kyoto Protocol: A revisit of Environmental Kuznets Curve hypothesis

Energy Technology Data Exchange (ETDEWEB)

Huang Weiming [Graduate Institute of Environmental Engineering, National Taiwan University, 71, Chou-Shan Road, Taipei 106, Taiwan (China); Lee, Grace W.M. [Graduate Institute of Environmental Engineering, National Taiwan University, 71, Chou-Shan Road, Taipei 106, Taiwan (China)], E-mail: gracelee@ntu.edu.tw; Wu Chihcheng [Energy and Air Pollution Control Section, New Materials R and D Department, China Steel Corporation, 1, Chung-Kang Road, Siaogang District, Kaohsiung 81233, Taiwan (China)

2008-01-15

The Kyoto Protocol attempts through political negotiations to guide participating industrialized countries' greenhouse gas (GHG) emissions from a positive growing trend, to reach a peak point (or turning point), and then be reduced to a negative growth. That means the relationship between decreasing GHG emissions and economic growth may be described by an inverted-U curve (or called a bell-shaped curve), which is consistent with the concept of the Environmental Kuznets Curve (EKC) hypothesis. This research observed that the economic development and GHG emissions in Economies in Transition (EITs) exhibit a hockey-stick curve trend (or called quasi-L-shape curve), that also generates a lot of 'hot air' which is significant to the implementation of the Kyoto Protocol. In addition, through the analysis of single-country time series data and GDP data, this research demonstrated that statistical data for most of the Annex II countries do not possess evidence that supports the EKC hypothesis for GHG emissions. The results from this study also indicated that the 38 industrialized countries are unable to meet their targets under the Kyoto Protocol within the specified time period, which are probably caused by the econometric method's inability to predict accurately the extents and development of innovative technologies and Clean Development Mechanism (CDM) projects. If the international community truly wants to reduce the GHG emissions, the effectiveness of the existing international framework for emissions reduction needs to be reconsidered seriously, and the global cooperation mechanism also needs to be greatly enhanced.

GHG emissions, GDP growth and the Kyoto Protocol: A revisit of Environmental Kuznets Curve hypothesis

International Nuclear Information System (INIS)

Huang Weiming; Lee, Grace W.M.; Wu Chihcheng

2008-01-01

The Kyoto Protocol attempts through political negotiations to guide participating industrialized countries' greenhouse gas (GHG) emissions from a positive growing trend, to reach a peak point (or turning point), and then be reduced to a negative growth. That means the relationship between decreasing GHG emissions and economic growth may be described by an inverted-U curve (or called a bell-shaped curve), which is consistent with the concept of the Environmental Kuznets Curve (EKC) hypothesis. This research observed that the economic development and GHG emissions in Economies in Transition (EITs) exhibit a hockey-stick curve trend (or called quasi-L-shape curve), that also generates a lot of 'hot air' which is significant to the implementation of the Kyoto Protocol. In addition, through the analysis of single-country time series data and GDP data, this research demonstrated that statistical data for most of the Annex II countries do not possess evidence that supports the EKC hypothesis for GHG emissions. The results from this study also indicated that the 38 industrialized countries are unable to meet their targets under the Kyoto Protocol within the specified time period, which are probably caused by the econometric method's inability to predict accurately the extents and development of innovative technologies and Clean Development Mechanism (CDM) projects. If the international community truly wants to reduce the GHG emissions, the effectiveness of the existing international framework for emissions reduction needs to be reconsidered seriously, and the global cooperation mechanism also needs to be greatly enhanced

Population-Based Study of the Epidemiology of Herpes Zoster in Korea

OpenAIRE

Kim, You Jeong; Lee, Chang Nam; Lim, Chi-Yeon; Jeon, Woo Seok; Park, Young Min

2014-01-01

General epidemiological data regarding herpes zoster (HZ) are necessary for treatment and prevention of this disease. In addition, epidemiological data can play an important role in evaluating the efficacy and impact of vaccination. Though several epidemiological studies of HZ in Korea have been conducted, they usually depend on hospital-based data and may not be representative of HZ characteristics all over Korea. The purpose of this study was to evaluate the incidence and other epidemiologi...

The emergence of translational epidemiology: from scientific discovery to population health impact.

Science.gov (United States)

Khoury, Muin J; Gwinn, Marta; Ioannidis, John P A

2010-09-01

Recent emphasis on translational research (TR) is highlighting the role of epidemiology in translating scientific discoveries into population health impact. The authors present applications of epidemiology in TR through 4 phases designated T1-T4, illustrated by examples from human genomics. In T1, epidemiology explores the role of a basic scientific discovery (e.g., a disease risk factor or biomarker) in developing a "candidate application" for use in practice (e.g., a test used to guide interventions). In T2, epidemiology can help to evaluate the efficacy of a candidate application by using observational studies and randomized controlled trials. In T3, epidemiology can help to assess facilitators and barriers for uptake and implementation of candidate applications in practice. In T4, epidemiology can help to assess the impact of using candidate applications on population health outcomes. Epidemiology also has a leading role in knowledge synthesis, especially using quantitative methods (e.g., meta-analysis). To explore the emergence of TR in epidemiology, the authors compared articles published in selected issues of the Journal in 1999 and 2009. The proportion of articles identified as translational doubled from 16% (11/69) in 1999 to 33% (22/66) in 2009 (P = 0.02). Epidemiology is increasingly recognized as an important component of TR. By quantifying and integrating knowledge across disciplines, epidemiology provides crucial methods and tools for TR.

Issues in epidemiological studies of radiofrequency workers

International Nuclear Information System (INIS)

Hocking, B.

1985-01-01

The paper reviews some of the issues in a proposed epidemiological study of radiofrequency workers. First a few other epidemiological studies are discussed to illustrate some of the common problems such as inadequate definition of effects and/or exposure. Then technical problems in determining dosage and responses as well as study design are reviewed, and finally the administrative aspects of ethics, industrial relations and costs are considered

Epidemiological studies on syncope

DEFF Research Database (Denmark)

Ruwald, Martin Huth

2013-01-01

of the patients play an essential role. In epidemiology these factors have major impact on the outcome of the patients. Until recently, even the definition of syncope differed from one study to another which has made literature reviews difficult. Traditionally the data on epidemiology of syncope has been taken...... from smaller studies from different clinical settings with wide differences in patient morbidity. Through the extensive Danish registries we examined the characteristics and prognosis of the patients hospitalized due to syncope in a nationwide study. The aims of the present thesis were to investigate......, prevalence and cardiovascular factors associated with the risk of syncope, 4) the prognosis in healthy individuals discharged after syncope, and 5) the prognosis of patients after syncope and evaluation of the CHADS2 score as a tool for short- and long-term risk prediction. The first studies of the present...

Importation, Mitigation, and Genomic Epidemiology of Candida auris at a Large Teaching Hospital.

Science.gov (United States)

Lesho, Emil P; Bronstein, Melissa Z; McGann, Patrick; Stam, Jason; Kwak, Yoon; Maybank, Rosslyn; McNamara, Jodi; Callahan, Megan; Campbell, Jean; Hinkle, Mary K; Walsh, Edward E

2018-01-01

OBJECTIVE Candida auris (CA) is an emerging multidrug-resistant pathogen associated with increased mortality. The environment may play a role, but transmission dynamics remain poorly understood. We sought to limit environmental and patient CA contamination following a sustained unsuspected exposure. DESIGN Quasi-experimental observation. SETTING A 528-bed teaching hospital. PATIENTS The index case patient and 17 collocated ward mates. INTERVENTION Immediately after confirmation of CA in the bloodstream and urine of a patient admitted 6 days previously, active surveillance, enhanced transmission-based precautions, environmental cleaning with peracetic acid-hydrogen peroxide and ultraviolet light, and patient relocation were undertaken. Pre-existing agreements and foundational relationships among internal multidisciplinary teams and external partners were leveraged to bolster detection and mitigation efforts and to provide genomic epidemiology. RESULTS Candida auris was isolated from 3 of 132 surface samples on days 8, 9, and 15 of ward occupancy, and from no patient samples (0 of 48). Environmental and patient isolates were genetically identical (4-8 single-nucleotide polymorphisms [SNPs]) and most closely related to the 2013 India CA-6684 strain (~200 SNPs), supporting the epidemiological hypothesis that the source of environmental contamination was the index case patient, who probably acquired the South Asian strain from another New York hospital. All isolates contained a mutation associated with azole resistance (K163R) found in the India 2105 VPCI strain but not in CA-6684. The index patient remained colonized until death. No surfaces were CA-positive 1 month later. CONCLUSION Compared to previous descriptions, CA dissemination was minimal. Immediate access to rapid CA diagnostics facilitates early containment strategies and outbreak investigations. Infect Control Hosp Epidemiol 2018;39:53-57.

Book citations: influence of epidemiologic thought in the academic community

Directory of Open Access Journals (Sweden)

Porta Miquel

2006-01-01

Full Text Available Whilst their 'death' has often been certified, books remain highly important to most professions and academic disciplines. Analyses of citations received by epidemiologic texts may complement other views on epidemiology. The objective was to assess the number of citations received by some books of epidemiology and public health, as a first step towards studying the influence of epidemiological thought and thinking in academia. For this purpose, Institute for Scientific Information/ Thomson Scientific - Web of Science/ Web of Knowledgedatabase was consulted, in May 2006. The book by Rothman & Greenland appeared to have received the highest number of citations overall (over 8,000 and per year. The books by Kleinbaum et al, and by Breslow & Day received around 5,000 citations. In terms of citations per year the book by Sackett et al ranks 3rd, and the one by Rose, 4th of those included in this preliminary study. Other books which were influential in the classrooms collected comparatively less citations. Results offer a rich picture of the academic influences and trends of epidemiologic methods and reasoning on public health, clinical medicine and the other health, life and social sciences. They may contribute to assess epidemiologists' efforts to demarcate epidemiology and to assert epistemic authority, and to analyze some historical influences of economic, social and political forces on epidemiological research.

Health system strengthening in Cambodia-a case study of health policy response to social transition.

Science.gov (United States)

Grundy, John; Khut, Qiu Yi; Oum, Sophal; Annear, Peter; Ky, Veng

2009-10-01

Cambodia, following decades of civil conflict and social and economic transition, has in the last 10 years developed health policy innovations in the areas of health contracting, health financing and health planning. This paper aims to outline recent social, epidemiological and demographic health trends in Cambodia, and on the basis of this outline, to analyse and discuss these policy responses to social transition. Sources of information included a literature review, participant observation in health planning development in Cambodia between 1993 and 2008, and comparative analysis of demographic health surveys between 2000 and 2005. In Cambodia there have been sharp but unequal improvements in child mortality, and persisting high maternal mortality rates. Data analysis demonstrates associations between location, education level and access to facility based care, suggesting the dominant role of socio-economic factors in determining access to facility based health care. These events are taking place against a background of rapid social transition in Cambodian history, including processes of decentralization, privatization and the development of open market economic systems. Primary policy responses of the Ministry of Health to social transition and associated health inequities include the establishment of health contracting, hospital health equity funds and public-private collaborations. Despite the internationally recognized health policy flexibility and innovation demonstrated in Cambodia, policy response still lags well behind the reality of social transition. In order to minimize the delay between transition and response, new policy making tactics are required in order to provide more flexible and timely responses to the ongoing social transition and its impacts on population health needs in the lowest socio-economic quintiles.

A Systematic Bayesian Integration of Epidemiological and Genetic Data

Science.gov (United States)

Lau, Max S. Y.; Marion, Glenn; Streftaris, George; Gibson, Gavin

2015-01-01

Genetic sequence data on pathogens have great potential to inform inference of their transmission dynamics ultimately leading to better disease control. Where genetic change and disease transmission occur on comparable timescales additional information can be inferred via the joint analysis of such genetic sequence data and epidemiological observations based on clinical symptoms and diagnostic tests. Although recently introduced approaches represent substantial progress, for computational reasons they approximate genuine joint inference of disease dynamics and genetic change in the pathogen population, capturing partially the joint epidemiological-evolutionary dynamics. Improved methods are needed to fully integrate such genetic data with epidemiological observations, for achieving a more robust inference of the transmission tree and other key epidemiological parameters such as latent periods. Here, building on current literature, a novel Bayesian framework is proposed that infers simultaneously and explicitly the transmission tree and unobserved transmitted pathogen sequences. Our framework facilitates the use of realistic likelihood functions and enables systematic and genuine joint inference of the epidemiological-evolutionary process from partially observed outbreaks. Using simulated data it is shown that this approach is able to infer accurately joint epidemiological-evolutionary dynamics, even when pathogen sequences and epidemiological data are incomplete, and when sequences are available for only a fraction of exposures. These results also characterise and quantify the value of incomplete and partial sequence data, which has important implications for sampling design, and demonstrate the abilities of the introduced method to identify multiple clusters within an outbreak. The framework is used to analyse an outbreak of foot-and-mouth disease in the UK, enhancing current understanding of its transmission dynamics and evolutionary process. PMID:26599399

Toxicology and Epidemiology: Improving the Science with a Framework for Combining Toxicological and Epidemiological Evidence to Establish Causal Inference

Science.gov (United States)

Adami, Hans-Olov; Berry, Sir Colin L.; Breckenridge, Charles B.; Smith, Lewis L.; Swenberg, James A.; Trichopoulos, Dimitrios; Weiss, Noel S.; Pastoor, Timothy P.

2011-01-01

Historically, toxicology has played a significant role in verifying conclusions drawn on the basis of epidemiological findings. Agents that were suggested to have a role in human diseases have been tested in animals to firmly establish a causative link. Bacterial pathogens are perhaps the oldest examples, and tobacco smoke and lung cancer and asbestos and mesothelioma provide two more recent examples. With the advent of toxicity testing guidelines and protocols, toxicology took on a role that was intended to anticipate or predict potential adverse effects in humans, and epidemiology, in many cases, served a role in verifying or negating these toxicological predictions. The coupled role of epidemiology and toxicology in discerning human health effects by environmental agents is obvious, but there is currently no systematic and transparent way to bring the data and analysis of the two disciplines together in a way that provides a unified view on an adverse causal relationship between an agent and a disease. In working to advance the interaction between the fields of toxicology and epidemiology, we propose here a five-step “Epid-Tox” process that would focus on: (1) collection of all relevant studies, (2) assessment of their quality, (3) evaluation of the weight of evidence, (4) assignment of a scalable conclusion, and (5) placement on a causal relationship grid. The causal relationship grid provides a clear view of how epidemiological and toxicological data intersect, permits straightforward conclusions with regard to a causal relationship between agent and effect, and can show how additional data can influence conclusions of causality. PMID:21561883

Three laws of energy transitions

International Nuclear Information System (INIS)

Bashmakov, Igor

2007-01-01

The paper formulates and explores a hypothesis on three general energy transition laws: the law of stable long-term energy costs to income ratio; the law of improving energy quality; and the law of growing energy productivity. These laws are essential for shaping long-term projections and checking for their consistency. All three are rooted in amazingly stable in time and universal across countries energy costs to income ratios. Limited energy purchasing power sets up thresholds, which, if exceeded, bring asymmetry to energy demand to price elasticity. The author believes, that the theoretical postulate on the substantial substitution among production factors, which is used in the production functions theory, may be incorrect. In reality, innovations mainly lead to the substitution of a low-quality production factor with the same yet of a better-quality. Improving energy quality with stable costs to income ratio is accompanied by growing energy productivity. Energy costs to income thresholds are indicators allowing for better projections of oil prices

The Random-Walk Hypothesis on the Indian Stock Market

OpenAIRE

Ankita Mishra; Vinod Mishra; Russell Smyth

2014-01-01

This study tests the random walk hypothesis for the Indian stock market. Using 19 years of monthly data on six indices from the National Stock Exchange (NSE) and the Bombay Stock Exchange (BSE), this study applies three different unit root tests with two structural breaks to analyse the random walk hypothesis. We find that unit root tests that allow for two structural breaks alone are not able to reject the unit root null; however, a recently developed unit root test that simultaneously accou...

The false alarm hypothesis: Food allergy is associated with high dietary advanced glycation end-products and proglycating dietary sugars that mimic alarmins.

Science.gov (United States)

Smith, Peter K; Masilamani, Madhan; Li, Xiu-Min; Sampson, Hugh A

2017-02-01

The incidence of food allergy has increased dramatically in the last few decades in westernized developed countries. We propose that the Western lifestyle and diet promote innate danger signals and immune responses through production of "alarmins." Alarmins are endogenous molecules secreted from cells undergoing nonprogrammed cell death that signal tissue and cell damage. High molecular group S (HMGB1) is a major alarmin that binds to the receptor for advanced glycation end-products (RAGE). Advanced glycation end-products (AGEs) are also present in foods. We propose the "false alarm" hypothesis, in which AGEs that are present in or formed from the food in our diet are predisposing to food allergy. The Western diet is high in AGEs, which are derived from cooked meat, oils, and cheese. AGEs are also formed in the presence of a high concentration of sugars. We propose that a diet high in AGEs and AGE-forming sugars results in misinterpretation of a threat from dietary allergens, promoting the development of food allergy. AGEs and other alarmins inadvertently prime innate signaling through multiple mechanisms, resulting in the development of allergic phenotypes. Current hypotheses and models of food allergy do not adequately explain the dramatic increase in food allergy in Western countries. Dietary AGEs and AGE-forming sugars might be the missing link, a hypothesis supported by a number of convincing epidemiologic and experimental observations, as discussed in this article. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

A pilot investigation to constrain the presence of ring systems around transiting exoplanets

Science.gov (United States)

Hatchett, W. Timothy; Barnes, Jason W.; Ahlers, John P.; MacKenzie, Shannon M.; Hedman, Matthew M.

2018-04-01

We demonstrate a process by which to evaluate the presence of large, Saturn-like ring systems around transiting extrasolar giant planets. We use extrasolar planet candidate KOI-422.01 as an example around which to establish limits on the presence of ring systems. We find that the spherical-planet (no-rings) fit matches the lightcurve of KOI-422.01 better than a lightcurve with a planet having obliquity angles 90°, 60°, 45°, or 20°. Hence we find no evidence for rings around KOI-422.01, but the methods that we have developed can be used for more comprehensive ring searches in the future. If the Hedman (2015) low-temperature rings hypothesis is correct, then the first positive detection of exorings might require transits of very long period ( ≳ 10 yr) giant planets outside their stars' ice lines.

Epidemiology of autoimmune diseases in Denmark

DEFF Research Database (Denmark)

Eaton, William W.; Rose, N.R.; Kalaydijan, A.

2007-01-01

An epidemiologic study of the autoimmune diseases taken together has not been done heretofore. The National Patient Register of Denmark is used to estimate the population prevalence of 31 possible or probable autoimmune diseases. Record linkage is used to estimate 465 pairwise co-morbidities in i......An epidemiologic study of the autoimmune diseases taken together has not been done heretofore. The National Patient Register of Denmark is used to estimate the population prevalence of 31 possible or probable autoimmune diseases. Record linkage is used to estimate 465 pairwise co...

The Cognitive Mediation Hypothesis Revisited: An Empirical Response to Methodological and Theoretical Criticism.

Science.gov (United States)

Romero, Anna A.; And Others

1996-01-01

In order to address criticisms raised against the cognitive mediation hypothesis, three experiments were conducted to develop a more direct test of the hypothesis. Taken together, the three experiments provide converging support for the cognitive mediation hypothesis, reconfirming the central role of cognition in the persuasion process.…

Consumer health information seeking as hypothesis testing.

Science.gov (United States)

Keselman, Alla; Browne, Allen C; Kaufman, David R

2008-01-01

Despite the proliferation of consumer health sites, lay individuals often experience difficulty finding health information online. The present study attempts to understand users' information seeking difficulties by drawing on a hypothesis testing explanatory framework. It also addresses the role of user competencies and their interaction with internet resources. Twenty participants were interviewed about their understanding of a hypothetical scenario about a family member suffering from stable angina and then searched MedlinePlus consumer health information portal for information on the problem presented in the scenario. Participants' understanding of heart disease was analyzed via semantic analysis. Thematic coding was used to describe information seeking trajectories in terms of three key strategies: verification of the primary hypothesis, narrowing search within the general hypothesis area and bottom-up search. Compared to an expert model, participants' understanding of heart disease involved different key concepts, which were also differently grouped and defined. This understanding provided the framework for search-guiding hypotheses and results interpretation. Incorrect or imprecise domain knowledge led individuals to search for information on irrelevant sites, often seeking out data to confirm their incorrect initial hypotheses. Online search skills enhanced search efficiency, but did not eliminate these difficulties. Regardless of their web experience and general search skills, lay individuals may experience difficulty with health information searches. These difficulties may be related to formulating and evaluating hypotheses that are rooted in their domain knowledge. Informatics can provide support at the levels of health information portals, individual websites, and consumer education tools.

Epidemiologic methods in mastitis treatment and control.

Science.gov (United States)

Thurmond, M C

1993-11-01

Methods and concepts of epidemiology offer means whereby udder health can be monitored and evaluated. Prerequisite to a sound epidemiologic approach is development of measures of mastitis that minimize biases and that account for sensitivity and specificity of diagnostic tests. Mastitis surveillance offers an ongoing and passive system for evaluation of udder health, whereas clinical and observational trials offer a more proactive and developmental approach to improving udder health.

"Epidemiological criminology": coming full circle.

Science.gov (United States)

Akers, Timothy A; Lanier, Mark M

2009-03-01

Members of the public health and criminal justice disciplines often work with marginalized populations: people at high risk of drug use, health problems, incarceration, and other difficulties. As these fields increasingly overlap, distinctions between them are blurred, as numerous research reports and funding trends document. However, explicit theoretical and methodological linkages between the 2 disciplines remain rare. A new paradigm that links methods and statistical models of public health with those of their criminal justice counterparts is needed, as are increased linkages between epidemiological analogies, theories, and models and the corresponding tools of criminology. We outline disciplinary commonalities and distinctions, present policy examples that integrate similarities, and propose "epidemiological criminology" as a bridging framework.

Quality transformation of dissolved organic carbon during water transit through lakes: contrasting controls by photochemical and biological processes

Science.gov (United States)

Berggren, Martin; Klaus, Marcus; Panneer Selvam, Balathandayuthabani; Ström, Lena; Laudon, Hjalmar; Jansson, Mats; Karlsson, Jan

2018-01-01

Dissolved organic carbon (DOC) may be removed, transformed, or added during water transit through lakes, resulting in changes in DOC composition and pigmentation (color). However, the process-based understanding of these changes is incomplete, especially for headwater lakes. We hypothesized that because heterotrophic bacteria preferentially consume noncolored DOC, while photochemical processing removes colored fractions, the overall changes in DOC color upon water passage through a lake depend on the relative importance of these two processes, accordingly. To test this hypothesis we combined laboratory experiments with field studies in nine boreal lakes, assessing both the relative importance of different DOC decay processes (biological or photochemical) and the loss of color during water transit time (WTT) through the lakes. We found that influence from photo-decay dominated changes in DOC quality in the epilimnia of relatively clear headwater lakes, resulting in systematic and selective net losses of colored DOC. However, in highly pigmented brown-water lakes (absorbance at 420 nm > 7 m-1) biological processes dominated, and there was no systematic relationship between color loss and WTT. Moreover, in situ data and dark experiments supported our hypothesis on the selective microbial removal of nonpigmented DOC, mainly of low molecular weight, leading to persistent water color in these highly colored lakes. Our study shows that brown headwater lakes may not conform to the commonly reported pattern of the selective removal of colored constituents in freshwaters, as DOC can show a sustained degree of pigmentation upon transit through these lakes.

Epidemiological studies of radiation workers in nuclear facilities

International Nuclear Information System (INIS)

Iwai, Satoshi; Semba, Tsuyoshi; Ishida, Kenji; Takagi, Syunji; Igari, Takafumi

2017-01-01

Regarding workers at nuclear facilities, this paper described INWORKS epidemiological research published in 2015, cooperative cohort epidemiological research of IARC 15 countries 10 years before that (15-country study), and the flow of radiation epidemiological research in the period from 15-country study to INWORKS. INWORKS is a retrospective cohort study to investigate the correlation between mortality due to solid cancer, blood cancer, and cardiovascular diseases in workers in three countries of France / the U.K. / the U.S. and low dose exposure through long-term photon external exposure. It obtained the data showing the statistical significance of increased cancer death rate. However, from the subjects of the analysis, no significant evaluation was made on neutron exposure and internal exposure. Statistically significant cancer mortality was confirmed in 15-country study at low dose, low dose rate, and prolonged exposure, but significant cancer mortality rate could not be confirmed excluding Canadian data, which had problems in dose evaluation. In the epidemiological studies of cancer mortality rates of radiation workers in nuclear power industries performed in France / the U.K. / the U.S. in the period ranging from 15-country study to INWORKS, significant difference was not recognized between cancer death rate and excessive relative risk (ERR) compared with LSS epidemiological research studies that handled acute exposure. Several tasks are still remaining. (A.O.)

Challenges and Opportunities for Occupational Epidemiology in the Twenty-first Century.

Science.gov (United States)

Stayner, L T; Collins, J J; Guo, Y L; Heederik, D; Kogevinas, M; Steenland, K; Wesseling, C; Demers, P A

2017-09-01

There are many opportunities and challenges for conducting occupational epidemiologic studies today. In this paper, we summarize the discussion of a symposium held at the Epidemiology in Occupational Health (EPICOH) conference, Chicago 2014, on challenges for occupational epidemiology in the twenty-first century. The increasing number of publications and attendance at our conferences suggests that worldwide interest in occupational epidemiology has been growing. There are clearly abundant opportunities for new research in occupational epidemiology. Areas ripe for further work include developing improved methods for exposure assessment, statistical analysis, studying migrant workers and other vulnerable populations, the use of biomarkers, and new hazards. Several major challenges are also discussed such as the rapidly changing nature and location of work, lack of funding, and political/legal conflicts. As long as work exists there will be occupational diseases that demand our attention, and a need for epidemiologic studies designed to characterize these risks and to support the development of preventive strategies. Despite the challenges and given the important past contribution in this field, we are optimistic about the importance and continued vitality of the research field of occupational epidemiology.

On the generalized gravi-magnetic hypothesis

International Nuclear Information System (INIS)

Massa, C.

1989-01-01

According to a generalization of the gravi-magnetic hypothesis (GMH) any neutral mass moving in a curvilinear path with respect to an inertial frame creates a magnetic field, dependent on the curvature radius of the path. A simple astrophysical consequence of the generalized GMH is suggested considering the special cases of binary pulsars and binary neutron stars

The (not so immortal strand hypothesis

Directory of Open Access Journals (Sweden)

Cristian Tomasetti

2015-03-01

Significance: Utilizing an approach that is fundamentally different from previous efforts to confirm or refute the immortal strand hypothesis, we provide evidence against non-random segregation of DNA during stem cell replication. Our results strongly suggest that parental DNA is passed randomly to stem cell daughters and provides new insight into the mechanism of DNA replication in stem cells.

Molecular Epidemiology of Bovine Tuberculosis and most Common ...

African Journals Online (AJOL)

Even though tuberculosis is endemic in Nigeria, information on the epidemiology of the disease especially bovine tuberculosis is still very scanty. Variable Number of Tandem Repeat (VNTR) was carried out on 113 tissue samples to have an idea of not only the epidemiology of bovine tuberculosis but also the most common ...

Has epidemiology become infatuated with methods? A historical perspective on the place of methods during the classical (1945-1965) phase of epidemiology.

Science.gov (United States)

Morabia, Alfredo

2015-03-18

Before World War II, epidemiology was a small discipline, practiced by a handful of people working mostly in the United Kingdom and in the United States. Today it is practiced by tens of thousands of people on all continents. Between 1945 and 1965, during what is known as its "classical" phase, epidemiology became recognized as a major academic discipline in medicine and public health. On the basis of a review of the historical evidence, this article examines to which extent classical epidemiology has been a golden age of an action-driven, problem-solving science, in which epidemiologists were less concerned with the sophistication of their methods than with the societal consequences of their work. It also discusses whether the paucity of methods stymied or boosted classical epidemiology's ability to convince political and financial agencies about the need to intervene in order to improve the health of the people.

Enhancement of the nonlinear optical absorption of the E7 liquid crystal at the nematic-isotropic transition

International Nuclear Information System (INIS)

Gomez, S.L.; Lenart, V.M.; Bechtold, I.H.; Figueiredo Neto, A.M.

2012-01-01

We present an experimental study of the nonlinear optical absorption of the eutectic mixture E7 at the nematic-isotropic phase transition by the Z-scan technique, under continuous-wave excitation at 532 nm. In the nematic region, the effective nonlinear optical coefficient P, which vanishes in the isotropic phase, is negative for the extraordinary beam and positive for an ordinary beam. The parameter SNL, whose definition in terms of the nonlinear absorption coefficient follows the definition of the optical-order parameter in terms of the linear dichroic ratio, behaves like an order parameter with critical exponent 0.22 ± 0.05, in good agreement with the tricritical hypothesis for the nematic isotropic transition. (author)

The Epidemiology of Pheochromocytoma

DEFF Research Database (Denmark)

Ladefoged Ebbehøj, Andreas

2017-01-01

Pheochromocytoma and catecholamine secreting paraganglioma (PPGL) are exceedingly rare endocrine tumours, but remain a frequent diagnostic dilemma due to their potential life-threatening nature. Reliable data on the epidemiology of PPGL is lacking and no time trends in incidence rates (IR) have...

Mechanisms of eyewitness suggestibility: tests of the explanatory role hypothesis.

Science.gov (United States)

Rindal, Eric J; Chrobak, Quin M; Zaragoza, Maria S; Weihing, Caitlin A

2017-10-01

In a recent paper, Chrobak and Zaragoza (Journal of Experimental Psychology: General, 142(3), 827-844, 2013) proposed the explanatory role hypothesis, which posits that the likelihood of developing false memories for post-event suggestions is a function of the explanatory function the suggestion serves. In support of this hypothesis, they provided evidence that participant-witnesses were especially likely to develop false memories for their forced fabrications when their fabrications helped to explain outcomes they had witnessed. In three experiments, we test the generality of the explanatory role hypothesis as a mechanism of eyewitness suggestibility by assessing whether this hypothesis can predict suggestibility errors in (a) situations where the post-event suggestions are provided by the experimenter (as opposed to fabricated by the participant), and (b) across a variety of memory measures and measures of recollective experience. In support of the explanatory role hypothesis, participants were more likely to subsequently freely report (E1) and recollect the suggestions as part of the witnessed event (E2, source test) when the post-event suggestion helped to provide a causal explanation for a witnessed outcome than when it did not serve this explanatory role. Participants were also less likely to recollect the suggestions as part of the witnessed event (on measures of subjective experience) when their explanatory strength had been reduced by the presence of an alternative explanation that could explain the same outcome (E3, source test + warning). Collectively, the results provide strong evidence that the search for explanatory coherence influences people's tendency to misremember witnessing events that were only suggested to them.

Transforming Epidemiology for 21st Century Medicine and Public Health

Science.gov (United States)

Khoury, Muin J.; Lam, Tram Kim; Ioannidis, John P.A.; Hartge, Patricia; Spitz, Margaret R.; Buring, Julie E.; Chanock, Stephen J.; Croyle, Robert T.; Goddard, Katrina A.; Ginsburg, Geoffrey S.; Herceg, Zdenko; Hiatt, Robert A.; Hoover, Robert N.; Hunter, David J.; Kramer, Barnet S.; Lauer, Michael S.; Meyerhardt, Jeffrey A.; Olopade, Olufunmilayo I.; Palmer, Julie R.; Sellers, Thomas A.; Seminara, Daniela; Ransohoff, David F.; Rebbeck, Timothy R.; Tourassi, Georgia; Winn, Deborah M.; Zauber, Ann; Schully, Sheri D.

2013-01-01

In 2012, the National Cancer Institute (NCI) engaged the scientific community to provide a vision for cancer epidemiology in the 21st century. Eight overarching thematic recommendations, with proposed corresponding actions for consideration by funding agencies, professional societies, and the research community emerged from the collective intellectual discourse. The themes are (i) extending the reach of epidemiology beyond discovery and etiologic research to include multilevel analysis, intervention evaluation, implementation, and outcomes research; (ii) transforming the practice of epidemiology by moving towards more access and sharing of protocols, data, metadata, and specimens to foster collaboration, to ensure reproducibility and replication, and accelerate translation; (iii) expanding cohort studies to collect exposure, clinical and other information across the life course and examining multiple health-related endpoints; (iv) developing and validating reliable methods and technologies to quantify exposures and outcomes on a massive scale, and to assess concomitantly the role of multiple factors in complex diseases; (v) integrating “big data” science into the practice of epidemiology; (vi) expanding knowledge integration to drive research, policy and practice; (vii) transforming training of 21st century epidemiologists to address interdisciplinary and translational research; and (viii) optimizing the use of resources and infrastructure for epidemiologic studies. These recommendations can transform cancer epidemiology and the field of epidemiology in general, by enhancing transparency, interdisciplinary collaboration, and strategic applications of new technologies. They should lay a strong scientific foundation for accelerated translation of scientific discoveries into individual and population health benefits. PMID:23462917

The failure of academic epidemiology: witness for the prosecution.

Science.gov (United States)

Shy, C M

1997-03-15

Academic epidemiology has failed to develop the scientific methods and the knowledge base to support the fundamental public health mission of preventing disease and promoting health through organized community efforts. As a basic science of public health, epidemiology should attempt to understand health and disease from a community and ecologic perspective as a consequence of how society is organized and behaves, what impact social and economic forces have on disease incidence rates, and what community actions will be effective in altering incidence rates. However, as taught in most textbooks and as widely practiced by academicians, epidemiology has become a biomedical discipline focused on the distribution and determinants of disease in groups of individuals who happen to have some common characteristics, exposures, or diseases. The ecology of human health has not been addressed, and the societal context in which disease occurs has been either disregarded or deliberately abstracted from consideration. By essentially assuming that risk factors for disease in individuals can be summed to understand the causes of disease in populations, academic epidemiology has limited itself to a narrow biomedical perspective, thereby committing the bio-medical fallacy of inferring that disease in populations can be understood by studying risk factors for disease in individuals. Epidemiology should be redefined as a study of the distribution and societal determinants of the health status of populations. This definition provides a stronger link to be the primary mission of public health and places an appropriate emphasis on the social, economic, environmental, and cultural determinants of population health. Epidemiology must cross the boundaries of other population sciences and add to its scope a macro-epidemiology, a study of causes from a truly population perspective, considering health and disease within the context of the total human environment.

Perceptions of molecular epidemiology studies of HIV among stakeholders

Directory of Open Access Journals (Sweden)

Cynthia Schairer

2017-12-01

Full Text Available Background: Advances in viral sequence analysis make it possible to track the spread of infectious pathogens, such as HIV, within a population. When used to study HIV, these analyses (i.e., molecular epidemiology potentially allow inference of the identity of individual research subjects. Current privacy standards are likely insufficient for this type of public health research. To address this challenge, it will be important to understand how stakeholders feel about the benefits and risks of such research. Design and Methods: To better understand perceived benefits and risks of these research methods, in-depth qualitative interviews were conducted with HIV-infected individuals, individuals at high-risk for contracting HIV, and professionals in HIV care and prevention. To gather additional perspectives, attendees to a public lecture on molecular epidemiology were asked to complete an informal questionnaire. Results: Among those interviewed and polled, there was near unanimous support for using molecular epidemiology to study HIV. Questionnaires showed strong agreement about benefits of molecular epidemiology, but diverse attitudes regarding risks. Interviewees acknowledged several risks, including privacy breaches and provocation of anti-gay sentiment. The interviews also demonstrated a possibility that misunderstandings about molecular epidemiology may affect how risks and benefits are evaluated. Conclusions: While nearly all study participants agree that the benefits of HIV molecular epidemiology outweigh the risks, concerns about privacy must be addressed to ensure continued trust in research institutions and willingness to participate in research.

Visual perception and imagery: a new molecular hypothesis.

Science.gov (United States)

Bókkon, I

2009-05-01

Here, we put forward a redox molecular hypothesis about the natural biophysical substrate of visual perception and visual imagery. This hypothesis is based on the redox and bioluminescent processes of neuronal cells in retinotopically organized cytochrome oxidase-rich visual areas. Our hypothesis is in line with the functional roles of reactive oxygen and nitrogen species in living cells that are not part of haphazard process, but rather a very strict mechanism used in signaling pathways. We point out that there is a direct relationship between neuronal activity and the biophoton emission process in the brain. Electrical and biochemical processes in the brain represent sensory information from the external world. During encoding or retrieval of information, electrical signals of neurons can be converted into synchronized biophoton signals by bioluminescent radical and non-radical processes. Therefore, information in the brain appears not only as an electrical (chemical) signal but also as a regulated biophoton (weak optical) signal inside neurons. During visual perception, the topological distribution of photon stimuli on the retina is represented by electrical neuronal activity in retinotopically organized visual areas. These retinotopic electrical signals in visual neurons can be converted into synchronized biophoton signals by radical and non-radical processes in retinotopically organized mitochondria-rich areas. As a result, regulated bioluminescent biophotons can create intrinsic pictures (depictive representation) in retinotopically organized cytochrome oxidase-rich visual areas during visual imagery and visual perception. The long-term visual memory is interpreted as epigenetic information regulated by free radicals and redox processes. This hypothesis does not claim to solve the secret of consciousness, but proposes that the evolution of higher levels of complexity made the intrinsic picture representation of the external visual world possible by regulated

Some consequences of using the Horsfall-Barratt scale for hypothesis testing

Science.gov (United States)

Comparing treatment effects by hypothesis testing is a common practice in plant pathology. Nearest percent estimates (NPEs) of disease severity were compared to Horsfall-Barratt (H-B) scale data to explore whether there was an effect of assessment method on hypothesis testing. A simulation model ba...

Prospective detection of large prediction errors: a hypothesis testing approach

International Nuclear Information System (INIS)

Ruan, Dan

2010-01-01

Real-time motion management is important in radiotherapy. In addition to effective monitoring schemes, prediction is required to compensate for system latency, so that treatment can be synchronized with tumor motion. However, it is difficult to predict tumor motion at all times, and it is critical to determine when large prediction errors may occur. Such information can be used to pause the treatment beam or adjust monitoring/prediction schemes. In this study, we propose a hypothesis testing approach for detecting instants corresponding to potentially large prediction errors in real time. We treat the future tumor location as a random variable, and obtain its empirical probability distribution with the kernel density estimation-based method. Under the null hypothesis, the model probability is assumed to be a concentrated Gaussian centered at the prediction output. Under the alternative hypothesis, the model distribution is assumed to be non-informative uniform, which reflects the situation that the future position cannot be inferred reliably. We derive the likelihood ratio test (LRT) for this hypothesis testing problem and show that with the method of moments for estimating the null hypothesis Gaussian parameters, the LRT reduces to a simple test on the empirical variance of the predictive random variable. This conforms to the intuition to expect a (potentially) large prediction error when the estimate is associated with high uncertainty, and to expect an accurate prediction when the uncertainty level is low. We tested the proposed method on patient-derived respiratory traces. The 'ground-truth' prediction error was evaluated by comparing the prediction values with retrospective observations, and the large prediction regions were subsequently delineated by thresholding the prediction errors. The receiver operating characteristic curve was used to describe the performance of the proposed hypothesis testing method. Clinical implication was represented by miss

A Hypothesis Concerning a Potential Involvement of Ceramide in Apoptosis and Acantholysis Induced by Pemphigus Autoantibodies

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Wendy B. Bollag

2010-01-01

Full Text Available Autoimmune diseases affect more than 50 million Americans, resulting in significant healthcare costs. Most autoimmune diseases occur sporadically; however, endemic pemphigus foliaceus (EPF is an autoimmune skin disease localized to specific geographic loci. EPF, and the related diseases pemphigus vulgaris (PV and pemphigus foliaceus (PF, are characterized by skin lesions and autoantibodies to molecules found on epidermal keratinocytes. A variant of EPF in patients from El Bagre, Colombia, South America, has recently been reported to be distinct from previously described loci in Brazil and Tunisia epidemiologically and immunologically. As in PF and EPF, El Bagre EPF patients exhibit autoantibodies towards desmoglein-1, a cell adhesion molecule critical for maintaining epidermal integrity. An association of El Bagre EPF with sun exposure has been detected, and ultraviolet irradiation also exacerbates symptoms in PV, PF and EPF. Our hypothesis is that: (1 the autoantibodies generate pathology through an alteration in ceramide metabolism in targeted keratinocytes, resulting in apoptosis and/or cell death and acantholysis, but only when the cell's ability to metabolize ceramide is exceeded, and (2 apoptosis in response to this altered ceramide metabolism is initiated and/or exacerbated by other agents that increase ceramide levels, such as cytokines, ultraviolet irradiation, and senescence.

A hypothesis concerning a potential involvement of ceramide in apoptosis and acantholysis induced by pemphigus autoantibodies.

Science.gov (United States)

Bollag, Wendy B

2010-01-01

Autoimmune diseases affect more than 50 million Americans, resulting in significant healthcare costs. Most autoimmune diseases occur sporadically; however, endemic pemphigus foliaceus (EPF) is an autoimmune skin disease localized to specific geographic loci. EPF, and the related diseases pemphigus vulgaris (PV) and pemphigus foliaceus (PF), are characterized by skin lesions and autoantibodies to molecules found on epidermal keratinocytes. A variant of EPF in patients from El Bagre, Colombia, South America, has recently been reported to be distinct from previously described loci in Brazil and Tunisia epidemiologically and immunologically. As in PF and EPF, El Bagre EPF patients exhibit autoantibodies towards desmoglein-1, a cell adhesion molecule critical for maintaining epidermal integrity. An association of El Bagre EPF with sun exposure has been detected, and ultraviolet irradiation also exacerbates symptoms in PV, PF and EPF. Our hypothesis is that: (1) the autoantibodies generate pathology through an alteration in ceramide metabolism in targeted keratinocytes, resulting in apoptosis and/or cell death and acantholysis, but only when the cell's ability to metabolize ceramide is exceeded, and (2) apoptosis in response to this altered ceramide metabolism is initiated and/or exacerbated by other agents that increase ceramide levels, such as cytokines, ultraviolet irradiation, and senescence.

The combination of phylogenetic analysis with epidemiological and serological data to track HIV-1 transmission in a sexual transmission case.

Directory of Open Access Journals (Sweden)

Min Chen

Full Text Available To investigate the linkage of HIV transmission from a man to a woman through unprotected sexual contact without disclosing his HIV-positive status.Combined with epidemiological information and serological tests, phylogenetic analysis was used to test the a priori hypothesis of HIV transmission from the man to the woman. Control subjects, infected with HIV through heterosexual intercourse, from the same location were also sampled. Phylogenetic analyses were performed using the consensus gag, pol and env sequences obtained from blood samples of the man, the woman and the local control subjects. The env quasispecies of the man, the woman, and two controls were also obtained using single genome amplification and sequencing (SGA/S to explore the paraphyletic relationship by phylogenetic analysis.Epidemiological information and serological tests indicated that the man was infected with HIV-1 earlier than the woman. Phylogenetic analyses of the consensus sequences showed a monophyletic cluster for the man and woman in all three genomic regions. Furthermore, gag sequences of the man and woman shared a unique recombination pattern from subtype B and C, which was different from those of CRF07_BC or CRF08_BC observed in the local samples. These indicated that the viral sequences from the two subjects display a high level of similarity. Further, viral quasispecies from the man exhibited a paraphyletic relationship with those from the woman in the Bayesian and maximum-likelihood (ML phylogenetic trees of the env region, which supported the transmission direction from the man to the woman.In the context of epidemiological and serological evidence, the results of phylogenetic analyses support the transmission from the man to the woman.

Chancroid epidemiology in New Orleans men.

Science.gov (United States)

DiCarlo, R P; Armentor, B S; Martin, D H

1995-08-01

Epidemiologic, clinical, and microbiologic data were collected from 299 men with nonsyphilitic genital ulcer disease. One hundred eighteen (39%) were culture-positive for Haemophilus ducreyi, 57 (19%) were culture-positive for herpes simplex virus, and 124 (41%) were culture-negative. Patients with chancroid were significantly more likely than those with genital herpes to have been frequent users of alcohol (44% vs. 23%, P = .006). They were also more likely recently to have used cocaine (25% vs. 9%, P = .013), had sex with a prostitute (17% vs. 5%, P = .035), traded drugs for sex (16% vs. 2%, P = .005), and had a sex partner who used drugs (38% vs. 13%, P = .001). Culture-negative patients were similar to chancroid patients with respect to most epidemiologic risk factors. Despite the epidemiologic similarities, the clinical features of culture-negative ulcers resembled those of culture-proven herpes ulcers more closely than they did those of culture-proven chancroid ulcers. These data establish a link between chancroid in the United States and the use of crack cocaine.

Relics of the cosmological quark-hadron phase transition

International Nuclear Information System (INIS)

Sinha, Bikash

2001-01-01

In this talk I will not dwell further on the nature of the Q -> H transition, Instead, I will simply assume that it is a phase transition, and further, a first-order phase transition, in which case, there is a possibility that a particular kind of relics called quark nuggets (QNs) containing a large fraction of the net baryon number of the universe may have been formed at the end of such a phase transition. The QNs would have tremendous implications for cosmology and astrophysics. In particular, they can be a good candidate for the baryonic dark matter in the universe provided they can survive up to the present epoch. The QNs which survived and floating around the universe, is there any connection with the recently discovered MACHOs between the earth and the Large Magellanic clouds. The QNs are hypothesized to be made of 'strange matter' which is composed of a roughly equal mixture of u, d, and s quarks at a density ≥ nuclear density. It has been hypothesized that at zero temperature and zero pressure the true ground state of hadronic matter could be SM rather than 56 Fe, the energy per baryon in SM could be lower that in ordinary nuclear matter. The latter would, however, still be effectively stable against decay would require high order simultaneous weak interaction process with a life-time much greater than the age of the universe. For certain ranges of values of parameters involved, namely, the QCD fine structure constant (α c ), mass of the strange quark (m s ), the vacuum bag energy (B), the hypothesis of SM being the absolutely stable of hadronic matter has been found to be quite plausible. (author)

Epidemiological Study of Heart Failure in China

Directory of Open Access Journals (Sweden)

Yang Guo

2015-10-01

Full Text Available Heart failure (HF is a complex clinical syndrome that results from any structural or functional impairment of ventricular filling or ejection of blood. HF is one of the most important and severe end stages of many cardiovascular diseases. Epidemiological studies of HF have focused mainly on the prevalence, incidence, mortality, fatality, and distribution and temporal trends of these indicators among different populations. This review highlights important epidemiological studies of HF in China.

1995 annual epidemiologic surveillance report for Hanford Site

International Nuclear Information System (INIS)

1995-01-01

The US Department of Energy's (DOE) commitment to assuring the health and safety of its workers includes the conduct of epidemiologic surveillance activities that provide an early warning system for health problems among workers. A number of DOE sites participate in the Epidemiologic Surveillance Program. This program monitors illnesses and health conditions that result in an absence of five or more consecutive workdays, occupational injuries and illnesses, disabilities and deaths among current workers. This report provides a summary of epidemiologic surveillance data collected from the Hanford Site from January 1, 1995 through December 31, 1995. The data were collected by a coordinator at Hanford and submitted to the Epidemiologic Surveillance Data Center, located at Oak Ridge Institute for Science and Education, where quality control procedures and data analyses were carried out. The information in the main body of the report provides a descriptive analysis of the data collected from the site, and the appendices provides additional detail. The report also contains an expanded Glossary and an Explanation of Diagnostic Categories which gives examples of health conditions in each of the diagnostic categories

1995 annual epidemiologic surveillance report for Hanford Site

Energy Technology Data Exchange (ETDEWEB)

NONE

1995-12-31

The US Department of Energy`s (DOE) commitment to assuring the health and safety of its workers includes the conduct of epidemiologic surveillance activities that provide an early warning system for health problems among workers. A number of DOE sites participate in the Epidemiologic Surveillance Program. This program monitors illnesses and health conditions that result in an absence of five or more consecutive workdays, occupational injuries and illnesses, disabilities and deaths among current workers. This report provides a summary of epidemiologic surveillance data collected from the Hanford Site from January 1, 1995 through December 31, 1995. The data were collected by a coordinator at Hanford and submitted to the Epidemiologic Surveillance Data Center, located at Oak Ridge Institute for Science and Education, where quality control procedures and data analyses were carried out. The information in the main body of the report provides a descriptive analysis of the data collected from the site, and the appendices provides additional detail. The report also contains an expanded Glossary and an Explanation of Diagnostic Categories which gives examples of health conditions in each of the diagnostic categories.

Biostatistics and epidemiology a primer for health and biomedical professionals

CERN Document Server

Wassertheil-Smoller, Sylvia

2015-01-01

Since the publication of the first edition, Biostatistics and Epidemiology has attracted loyal readers from across specialty areas in the biomedical community. Not only does this textbook teach foundations of epidemiological design and statistical methods, but it also includes topics applicable to new areas of research. Areas covered in the fourth edition include a new chapter on risk prediction, risk reclassification and evaluation of biomarkers, new material on propensity analyses, and a vastly expanded chapter on genetic epidemiology, which  is particularly relevant to those who wish to understand the epidemiological and statistical aspects of scientific articles in this rapidly advancing field. Biostatistics and Epidemiology was written to be accessible for readers without backgrounds in mathematics. It provides clear explanations of underlying principles, as well as practical guidelines of "how to do it" and "how to interpret it."a philosophical explanation of the logic of science, subsections that ...

The changing epidemiology of group B streptococcus bloodstream infection

DEFF Research Database (Denmark)

Ballard, Mark S; Schønheyder, Henrik C; Knudsen, Jenny Dahl

2016-01-01

Background Population-based studies conducted in single regions or countries have identified significant changes in the epidemiology of invasive group B streptococcus (GBS) infection. However, no studies have concurrently compared the epidemiology of GBS infections among multiple different region...

The large numbers hypothesis and a relativistic theory of gravitation

International Nuclear Information System (INIS)

Lau, Y.K.; Prokhovnik, S.J.

1986-01-01

A way to reconcile Dirac's large numbers hypothesis and Einstein's theory of gravitation was recently suggested by Lau (1985). It is characterized by the conjecture of a time-dependent cosmological term and gravitational term in Einstein's field equations. Motivated by this conjecture and the large numbers hypothesis, we formulate here a scalar-tensor theory in terms of an action principle. The cosmological term is required to be spatially dependent as well as time dependent in general. The theory developed is appled to a cosmological model compatible with the large numbers hypothesis. The time-dependent form of the cosmological term and the scalar potential are then deduced. A possible explanation of the smallness of the cosmological term is also given and the possible significance of the scalar field is speculated

Modeling mechanical properties of a shear thickening fluid damper based on phase transition theory

Science.gov (United States)

Wei, Minghai; Lin, Kun; Guo, Qian

2018-03-01

Shear thickening fluids (STFs) are highly concentrated colloidal suspensions consisting of monodisperse nano-particles suspended in a carrying fluid, and have the capacity to display both flowable and rigid behaviors, when subjected to sudden stimuli. In that process, the external energy that acts on an STF can be dissipated quickly. The aim of this study is to present a dynamic model of a damper filled with STF that can be directly used in control engineering fields. To this end, shear stress during phase transition of the STF material is chosen as an internal variable. A non-convex function with bifurcation behavior is used to describe the phase transitioning of STF by determining the relationship between the behavioral characteristics of the microscopic phase and macroscopic damping force. This model is able to predict force-velocity and force-displacement relationships as functions of the loading frequency. Efficacy of the model is demonstrated via comparison with experimental results from previous studies. In addition, the results confirm the hypothesis regarding the occurrence of STF phase transitioning when subject to shear stress.

Theoretical expression of the internal conversion coefficient of a M1 transition between two atomic states

International Nuclear Information System (INIS)

Attallah, F.; Chemin, J.F.; Scheurer, J.N.; Karpeshin, F.; Harston, M.

1997-01-01

We have established a general relation for the expression of the internal conversion of an M 1 transition a 1s electronic state to an empty ns electronic bound state. Under the hypothesis that the density of the electron level ρ n satisfies the condition ρ n Γ >> 1 (where Γ is the total width of the excited atomic state) a calculation in the first order gives a relation for the internal conversion coefficient.This relation shows that the internal conversion coefficient takes a resonant character when the nuclear energy transition is smaller than the binding energy of the 1s electron. An application of this relation to an M 1 transition in the case of the ion 125 T e with a charge state Q = 45 and an 1s electron binding energy E B 45 = 35.581 KeV gives the value for the internal conversion coefficient R = 5.7

Acute respiratory distress syndrome: epidemiology and management approaches

Directory of Open Access Journals (Sweden)

Walkey AJ

2012-07-01

Full Text Available Allan J Walkey,1 Ross Summer,1 Vu Ho,1 Philip Alkana21The Pulmonary Center, Boston University School of Medicine, Boston, MA, USA; 2Asthma Research Center, Brigham and Women's Hospital, Boston, MA, USAAbstract: Acute lung injury and the more severe acute respiratory distress syndrome represent a spectrum of lung disease characterized by the sudden onset of inflammatory pulmonary edema secondary to myriad local or systemic insults. The present article provides a review of current evidence in the epidemiology and treatment of acute lung injury and acute respiratory distress syndrome, with a focus on significant knowledge gaps that may be addressed through epidemiologic methods.Keywords: acute lung injury, acute respiratory distress syndrome, review, epidemiology

Molecular Epidemiology of Brucella abortus in Northern Ireland-1991 to 2012.

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Adrian Allen

Full Text Available Brucellosis is the most common bacterial zoonoses worldwide. Bovine brucellosis caused by Brucella abortus has far reaching animal health and economic impacts at both the local and national levels. Alongside traditional veterinary epidemiology, the use of molecular typing has recently been applied to inform on bacterial population structure and identify epidemiologically-linked cases of infection. Multi-locus variable number tandem repeat VNTR analysis (MLVA was used to investigate the molecular epidemiology of a well-characterised Brucella abortus epidemic in Northern Ireland involving 387 herds between 1991 and 2012.MLVA identified 98 unique B. abortus genotypes from disclosing isolates in the 387 herds involved in the epidemic. Clustering algorithms revealed the relatedness of many of these genotypes. Combined with epidemiological information on chronology of infection and geographic location, these genotype data helped to identify 7 clonal complexes which underpinned the outbreak over the defined period. Hyper-variability of some VNTR loci both within herds and individual animals led to detection of multiple genotypes associated with single outbreaks. However with dense sampling, these genotypes could still be associated with specific clonal complexes thereby permitting inference of epidemiological links. MLVA- based epidemiological monitoring data were congruent with an independent classical veterinary epidemiology study carried out in the same territory.MLVA is a useful tool in ongoing disease surveillance of B. abortus outbreaks, especially when combined with accurate epidemiological information on disease tracings, geographical clustering of cases and chronology of infection.

The African Field Epidemiology Network-Networking for effective field epidemiology capacity building and service delivery

Science.gov (United States)

Gitta, Sheba Nakacubo; Mukanga, David; Babirye, Rebecca; Dahlke, Melissa; Tshimanga, Mufuta; Nsubuga, Peter

2011-01-01

Networks are a catalyst for promoting common goals and objectives of their membership. Public Health networks in Africa are crucial, because of the severe resource limitations that nations face in dealing with priority public health problems. For a long time, networks have existed on the continent and globally, but many of these are disease-specific with a narrow scope. The African Field Epidemiology Network (AFENET) is a public health network established in 2005 as a non-profit networking alliance of Field Epidemiology and Laboratory Training Programs (FELTPs) and Field Epidemiology Training Programs (FETPs) in Africa. AFENET is dedicated to helping ministries of health in Africa build strong, effective and sustainable programs and capacity to improve public health systems by partnering with global public health experts. The Network's goal is to strengthen field epidemiology and public health laboratory capacity to contribute effectively to addressing epidemics and other major public health problems in Africa. AFENET currently networks 12 FELTPs and FETPs in sub-Saharan Africa with operations in 20 countries. AFENET has a unique tripartite working relationship with government technocrats from human health and animal sectors, academicians from partner universities, and development partners, presenting the Network with a distinct vantage point. Through the Network, African nations are making strides in strengthening their health systems. Members are able to: leverage resources to support field epidemiology and public health laboratory training and service delivery notably in the area of outbreak investigation and response as well as disease surveillance; by-pass government bureaucracies that often hinder and frustrate development partners; and consolidate efforts of different partners channelled through the FELTPs by networking graduates through alumni associations and calling on them to offer technical support in various public health capacities as the need arises

The Reaction Mechanism of Claisen Rearrangement Obtained by Transition State Spectroscopy and Single Direct-Dynamics Trajectory

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Takayoshi Kobayashi

2013-02-01

Full Text Available Chemical bond breaking and formation during chemical reactions can be observed using “transition state spectroscopy”. Comparing the measurement result of the transition state spectroscopy with the simulation result of single direct-dynamics trajectory, we have elucidated the reaction dynamics of Claisen rearrangement of allyl vinyl ether. Observed the reaction of the neat sample liquid, we have estimated the time constants of transformation from straight-chain structure to aromatic-like six-membered ring structure forming the C1-C6 bond. The result clarifies that the reaction proceeds via three steps taking longer time than expected from the gas phase calculation. This finding provides new hypothesis and discussions, helping the development of the field of reaction mechanism analysis.

Remarks about the hypothesis of limiting fragmentation

International Nuclear Information System (INIS)

Chou, T.T.; Yang, C.N.

1987-01-01

Remarks are made about the hypothesis of limiting fragmentation. In particular, the concept of favored and disfavored fragment distribution is introduced. Also, a sum rule is proved leading to a useful quantity called energy-fragmentation fraction. (author). 11 refs, 1 fig., 2 tabs

Vacuum counterexamples to the cosmic censorship hypothesis

International Nuclear Information System (INIS)

Miller, B.D.

1981-01-01

In cylindrically symmetric vacuum spacetimes it is possible to specify nonsingular initial conditions such that timelike singularities will (necessarily) evolve from these conditions. Examples are given; the spacetimes are somewhat analogous to one of the spherically symmetric counterexamples to the cosmic censorship hypothesis

Cocoa Polyphenols: Evidence from Epidemiological Studies.

Science.gov (United States)

Matsumoto, Chisa

2018-01-01

Accumulating evidence suggests potential preventive effects of chocolate/cocoa on the risk of cardio vascular disease (CVD). However, cocoa products also contain high levels of sugar and fat, which increase CVD risk factors. Even, the identity of the substance in chocolate/cocoa that has a favorable effect on CVD and CVD risk factors remains unclear, growing evidence from experimental studies suggests that cocoa polyphenols might be a major contributor to cardiovascular-protective effects. However, epidemiological studies, which are necessary to evaluate an association between the risk of CVD and cocoa polyphenol, remain sparse. We will discuss recent evidence regarding the association between cocoa polyphenol consumption and the risks of CVD and its risk factors by reviewing recent epidemiological studies. We shall also provide some guidance for patient counseling and will discuss the public health implications for recommending cocoa polyphenol consumption to prevent CVD. Epidemiological studies evaluating the association between cocoa polyphenol itself and the risk of CVD are sparse. However, evidence from limited epidemiological studies suggests that cocoa polyphenol consumption may lower the risk of CVD. Given the potential adverse effects of the consumption of cocoa products with high fat and sugar and the fact that the most appropriate dose of cocoa polyphenol for cardio-protective effects has not yet been established, health care providers should remain cautious about recommending cocoa/cocoa polyphenol consumption to their patients to reduce the risk of CVD, taking the characteristics of individual patients into careful consideration. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Divergence of relative difference in Gaussian distribution function and stochastic resonance in a bistable system with frictionless state transition

Science.gov (United States)

Kasai, Seiya; Ichiki, Akihisa; Tadokoro, Yukihiro

2018-03-01

A bistable system efficiently detects a weak signal by adding noise, which is referred to as stochastic resonance. A previous theory deals with friction in state transition; however, this hypothesis is inadequate when friction force is negligible such as in nano- and molecular-scale systems. We show that, when the transition occurs without friction, the sensitivity of the bistable system to a Gaussian-noise-imposed weak signal becomes significantly high. The sensitivity is determined by the relative difference in noise distribution function. We find that the relative difference in Gaussian distribution function diverges in its tail edge, resulting in a high sensitivity in the present system.

Genomic Resources for Cancer Epidemiology

Science.gov (United States)

This page provides links to research resources, complied by the Epidemiology and Genomics Research Program, that may be of interest to genetic epidemiologists conducting cancer research, but is not exhaustive.

Reverse hypothesis machine learning a practitioner's perspective

CERN Document Server

Kulkarni, Parag

2017-01-01

This book introduces a paradigm of reverse hypothesis machines (RHM), focusing on knowledge innovation and machine learning. Knowledge- acquisition -based learning is constrained by large volumes of data and is time consuming. Hence Knowledge innovation based learning is the need of time. Since under-learning results in cognitive inabilities and over-learning compromises freedom, there is need for optimal machine learning. All existing learning techniques rely on mapping input and output and establishing mathematical relationships between them. Though methods change the paradigm remains the same—the forward hypothesis machine paradigm, which tries to minimize uncertainty. The RHM, on the other hand, makes use of uncertainty for creative learning. The approach uses limited data to help identify new and surprising solutions. It focuses on improving learnability, unlike traditional approaches, which focus on accuracy. The book is useful as a reference book for machine learning researchers and professionals as ...

Birth/birth-death processes and their computable transition probabilities with biological applications.

Science.gov (United States)

Ho, Lam Si Tung; Xu, Jason; Crawford, Forrest W; Minin, Vladimir N; Suchard, Marc A

2018-03-01

Birth-death processes track the size of a univariate population, but many biological systems involve interaction between populations, necessitating models for two or more populations simultaneously. A lack of efficient methods for evaluating finite-time transition probabilities of bivariate processes, however, has restricted statistical inference in these models. Researchers rely on computationally expensive methods such as matrix exponentiation or Monte Carlo approximation, restricting likelihood-based inference to small systems, or indirect methods such as approximate Bayesian computation. In this paper, we introduce the birth/birth-death process, a tractable bivariate extension of the birth-death process, where rates are allowed to be nonlinear. We develop an efficient algorithm to calculate its transition probabilities using a continued fraction representation of their Laplace transforms. Next, we identify several exemplary models arising in molecular epidemiology, macro-parasite evolution, and infectious disease modeling that fall within this class, and demonstrate advantages of our proposed method over existing approaches to inference in these models. Notably, the ubiquitous stochastic susceptible-infectious-removed (SIR) model falls within this class, and we emphasize that computable transition probabilities newly enable direct inference of parameters in the SIR model. We also propose a very fast method for approximating the transition probabilities under the SIR model via a novel branching process simplification, and compare it to the continued fraction representation method with application to the 17th century plague in Eyam. Although the two methods produce similar maximum a posteriori estimates, the branching process approximation fails to capture the correlation structure in the joint posterior distribution.

The Relationship Between Caregiving and Mortality After Accounting for Time-Varying Caregiver Status and Addressing the Healthy Caregiver Hypothesis.

Science.gov (United States)

Fredman, Lisa; Lyons, Jennifer G; Cauley, Jane A; Hochberg, Marc; Applebaum, Katie M

2015-09-01

Previous studies have shown inconsistent associations between caregiving and mortality. This may be due to analyzing caregiver status at baseline only, and that better health is probably related to taking on caregiving responsibilities and continuing in that role. The latter is termed The Healthy Caregiver Hypothesis, similar to the Healthy Worker Effect in occupational epidemiology. We applied common approaches from occupational epidemiology to evaluate the association between caregiving and mortality, including treating caregiving as time-varying and lagging exposure up to 5 years. Caregiving status among 1,068 women (baseline mean age = 81.0 years; 35% caregivers) participating in the Caregiver-Study of Osteoporotic Fractures study was assessed at five interviews conducted between 1999 and 2009. Mortality was determined through January 2012. Cox proportional hazards models were used to estimate adjusted hazard ratios and 95% confidence intervals adjusted for sociodemographics, perceived stress, and functional limitations. A total of 483 participants died during follow-up (38.8% and 48.7% of baseline caregivers and noncaregivers, respectively). Using baseline caregiving status, the association with mortality was 0.77, 0.62-0.95. Models of time-varying caregiving status showed a more pronounced reduction in mortality in current caregivers (hazard ratios = 0.54, 0.38-0.75), which diminished with longer lag periods (3-year lag hazard ratio = 0.68, 0.52-0.88, 5-year lag hazard ratios = 0.76, 0.60-0.95). Overall, caregivers had lower mortality rates than noncaregivers in all analyses. These associations were sensitive to the lagged period, indicating that the timing of leaving caregiving does influence this relationship and should be considered in future investigations. © The Author 2015. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Epidemiology of subtypes of depression

DEFF Research Database (Denmark)

Kessing, L V

2007-01-01

depression, dysthymia, and subsyndromal states; the association between stressful life events and depression appears to diminish with the number of depressive episodes. Finally, recent genetic findings are congruent with a model indicating that the majority of depressions develop in the interplay between...... genes and stressful experiences, whereas 'reactive' depressions and 'endogenous' depressions apparently exist at a lower prevalence. CONCLUSION: Further longitudinal, analytical, and genetic epidemiologic studies are needed to reveal which conditions are mild and transient, and which may be precursors......OBJECTIVE: There is a general clinical impression that depression differs qualitatively from non-depressive conditions, and that it can be identified as a categorical entity. In contrast, epidemiological studies support the view that depression is dynamic in nature and develops on a continuous...

The Effectiveness of the Comprehension Hypothesis: A Review on the Current Research on Incidental Vocabulary Acquisition

Science.gov (United States)

Ponniah, Joseph

2011-01-01

The Comprehension Hypothesis (CH) is the most powerful hypothesis in the field of Second Language Acquisition despite the presence of the rivals the skill-building hypothesis, the output hypothesis, and the interaction hypothesis. The competing hypotheses state that consciously learned linguistic knowledge is a necessary step for the development…

From heresy to dogma in accounts of opposition to Howard Temin's DNA provirus hypothesis.

Science.gov (United States)

Marcum, James A

2002-01-01

In 1964 the Wisconsin virologist Howard Temin proposed the DNA provirus hypothesis to explain the mechanism by which a cancer-producing virus containing only RNA infects and transforms cells. His hypothesis reversed the flow of genetic information, as ordained by the central dogma of molecular biology. Although there was initial opposition to his hypothesis it was widely accepted, after the discovery of reverse transcriptase in 1970. Most accounts of Temin's hypothesis after the discovery portray the hypothesis as heretical, because it challenged the central dogma. Temin himself in his Nobel Prize speech of 1975 narrates a similar story about its reception. But are these accounts warranted? I argue that members of the virology community opposed Temin's provirus hypothesis not simply because it was a counterexample to the central dogma, but more importantly because his experimental evidence for supporting it was inconclusive. Furthermore, I propose that these accounts of opposition to the DNA provirus hypothesis as heretical, written by Temin and others after the discovery of reverse transcriptase, played a significant role in establishing retrovirology as a specialized field.

The limits to pride: A test of the pro-anorexia hypothesis.

Science.gov (United States)

Cornelius, Talea; Blanton, Hart

2016-01-01

Many social psychological models propose that positive self-conceptions promote self-esteem. An extreme version of this hypothesis is advanced in "pro-anorexia" communities: identifying with anorexia, in conjunction with disordered eating, can lead to higher self-esteem. The current study empirically tested this hypothesis. Results challenge the pro-anorexia hypothesis. Although those with higher levels of pro-anorexia identification trended towards higher self-esteem with increased disordered eating, this did not overcome the strong negative main effect of pro-anorexia identification. These data suggest a more effective strategy for promoting self-esteem is to encourage rejection of disordered eating and an anorexic identity.

Direct progeny detection techniques and random epidemiology

International Nuclear Information System (INIS)

Mayya, Y.S.; Mishra, Rosaline; Sapra, B.K.

2015-01-01

Over the past 40 years, there has been considerable progress in the measurements methods and their application to the estimates of risks due to radon among general populations. The previous decade saw major development in this regard. It was the direct estimate of indoor radon risk from epidemiological studies in Europe and North America. These were important findings that demonstrated the presence of lung cancer risks at residential radon levels supplementing the generally used risks estimates at high exposures obtained from uranium miner's data. The residential radon epidemiological studies largely used radon concentration as a measure of exposure. The exposure to decay products, which are primarily the dose givers, are assumed to be proportional to the measured gas concentrations. Also, the presence of thoron was neglected in these studies. Although several corrections have appeared to these assessments, the question of variability of actual decay product exposures has largely remained unaddressed. In order to circumvent this limitation, passive techniques were developed to estimate the decay product concentrations directly using deposition monitors. These are based on detecting the alpha particles from decay products deposited on an absorber mounted LR-115 detectors. Known as Direct radon, and Thoron Progeny sensors (DRPS/DTPS), these have been further refined to separate fine fraction from the coarse fraction by wire-mesh capping techniques. Large number environmental calibration exercises and field data generation has been carried out on the progeny concentrations in Indian and some European environments. The development of progeny sensors offers a new tool for future epidemiology. Since in the Indian context, there exist no radon related epidemiological estimates of risk, it is time one conducts large scale studies to seek possible correlations between DRPS/DTPS data and lung cancer risks. While epidemiological studies in High background radiation areas

Systematic reviews of epidemiology in diabetes: finding the evidence

Directory of Open Access Journals (Sweden)

Waugh Norman

2005-01-01

Full Text Available Abstract Background Methodological research to support searching for those doing systematic reviews of epidemiological studies is a relatively neglected area. Our aim was to determine how many databases it is necessary to search to ensure a comprehensive coverage of the literature in diabetes epidemiology, with the aim of examining the efficiency of searching in support of systematic reviews of the epidemiology of diabetes Methods Three approaches were used. First, we defined a set of English language diabetes journals and examined their coverage in bibliographic databases. Second, we searched extensively for diabetes epidemiology articles (in all languages to determine which are the most useful databases; and third, we analysed the scattering of these articles to determine the core journals in the area. Results The overlap between MEDLINE and Embase for diabetes journals was 59%. A search for diabetes epidemiology articles across both MEDLINE and Embase, showed that MEDLINE alone retrieved about 94% of the total articles. Searching for diabetes epidemiology studies beyond MEDLINE and Embase retrieved no additional English language journal articles. The only diabetes epidemiology studies found by searching beyond MEDLINE and Embase were found in LILACS, and were Spanish or Portuguese language studies from Latin America; no additional English language studies were found. Only 30% of the meeting abstracts were converted to full publication after three years. One third of journal articles were published in just six journals, with Diabetes Care contributing 14.3% of the articles, followed by Diabetic Medicine (5.0%; Diabetes Research & Clinical Practice (4.1%; Diabetologia (4.0%; Diabetes & Metabolism (2.4% and Diabetes (2.0%. Conclusions Our results show that when searching for articles on diabetes epidemiology, MEDLINE and Embase would suffice for English language papers, with LILACS giving some additional non-English articles from Latin America

Punctuated Equilibrium in Statistical Models of Generalized Coevolutionary Resilience: How Sudden Ecosystem Transitions Can Entrain Both Phenotype Expression and Darwinian Selection

Science.gov (United States)

Wallace, Rodrick; Wallace, Deborah

We argue that mesoscale ecosystem resilience shifts akin to sudden phase transitions in physical systems can entrain similarly punctuated events of gene expression on more rapid time scales, and, in part through such means, slower changes induced by selection pressure, triggering punctuated equilibrium Darwinian evolutionary transitions on geologic time scales. The approach reduces ecosystem, gene expression, and Darwinian genetic dynamics to a least common denominator of information sources interacting by crosstalk at markedly differing rates. Pettini's 'topological hypothesis', via a homology between information source uncertainty and free energy density, generates a regression-like class of statistical models of sudden coevolutionary phase transition based on the Rate Distortion and Shannon-McMillan Theorems of information theory which links all three levels. A mathematical treatment of Holling's extended keystone hypothesis regarding the particular role of mesoscale phenomena in entraining both slower and faster dynamical structures produces the result. A main theme is the necessity of a cognitive paradigm for gene expression, mirroring I. Cohen's cognitive approach to immune function. Invocation of the necessary conditions imposed by the asymptotic limit theorems of communication theory enables us to penetrate one layer more deeply before needing to impose an empirically-derived phenomenological system of 'Onsager relation' recursive coevolutionary stochastic differential equations. Extending the development to second order via a large deviations argument permits modeling the influence of human cultural structures on ecosystems as 'farming'.

Epidemiology, molecular epidemiology, and risk factors for renal cell carcinoma

Directory of Open Access Journals (Sweden)

Chiara Paglino

2011-12-01

Full Text Available Despite only accounting for approximately 2% of all new primary cancer cases, renal cell carcinoma (RCC incidence has dramatically increased over time. Incidence rates vary greatly according to geographic areas, so that it is extremely likely that exogenous risk factors could play an important role in the development of this cancer. Several risk factors have been linked with RCC, including cigarette smoking, obesity, hypertension (and antihypertensive drugs, chronic kidney diseases (also dialysis and transplantation, as well as the use of certain analgesics. Furthermore, although RCC has not generally been considered an occupational cancer, several types of occupationally-derived exposures have been implicated in its pathogenesis. These include exposure to asbestos, chlorinated solvents, gasoline, diesel exhaust fumes, polycyclic aromatic hydrocarbons, printing inks and dyes, cadmium and lead. Finally, families with a predisposition to the development of renal neoplasms were identified and the genes involved discovered and characterized. Therefore, there are now four well-characterized, genetically determined syndromes associated with an increased incidence of kidney tumors, i.e., Von Hippel Lindau (VHL, Hereditary Papillary Renal Carcinoma (HPRC, Birt-Hogg-Dubé Syndrome (BHD, and Hereditary Leiomyomatosis and Renal Cell Cancer (HLRCC. This review will address present knowledge about the epidemiology, molecular epidemiology and risk factors of RCC.

Epidemiology of Patellar Tendinopathy in Elite Male Soccer Players

NARCIS (Netherlands)

Hägglund, Martin; Zwerver, Johannes; Ekstrand, Jan

Background: Patellar tendinopathy is common among athletes in jumping sports and in sports with prolonged repetitive stress of the knee extensor apparatus. The epidemiology in soccer is not well described. Purpose: This study was undertaken to investigate and describe the epidemiology of patellar

Evolution of Motor Control: From Reflexes and Motor Programs to the Equilibrium-Point Hypothesis