Past Several Decades (past + several_decade)

Distribution by Scientific Domains


Selected Abstracts


Quantifying Plant Population Persistence in Human-Dominated Landscapes

CONSERVATION BIOLOGY, Issue 4 2008
DAWN M. LAWSON
Base de Datos de la Diversidad Natural de California; conservación de plantas; crecimiento de la población; especies en peligro; paisajes urbanos Abstract:,We assessed population performance of rare plants across a gradient from rural to urban landscapes and evaluated 2 hypotheses central to strategic conservation planning: (1) population performance declines with increasing human dominance and (2) small populations perform poorly relative to larger ones. Assessing these hypotheses is critical to strategic conservation planning. The current conservation paradigm adheres to the well-established ecology theory that small isolated populations, particularly those in human-dominated landscapes, are the least likely to succeed over the long term. Consequently, conservation planning has strongly favored large, remote targets for protection. This shift in conservation toward ecosystem-based programs and protection of populations within large, remote systems has been at the expense of protection of the rarest of the rare species, the dominant paradigm for conservation driven by the endangered species act. Yet, avoiding conservation of small populations appears to be based more on theoretical understanding and expert opinion than empiricism. We used Natural Heritage data from California in an assessment of population performance of rare plants across a landscape with an urban-rural gradient. Population performance did not decrease in urban settings or for populations that were initially small. Our results are consistent with a pattern of few species extinctions within these landscapes over the past several decades. We conclude that these populations within compromised landscapes can contribute to overall biodiversity conservation. We further argue that conservation planning for biodiversity preservation should allocate relatively more resources to protecting urban-associated plant taxa because they may provide conservation benefit beyond simply protecting isolated populations; they may be useful in building social interest in conservation. Resumen:,Evaluamos el funcionamiento de la población de plantas raras a lo largo de un gradiente de paisajes rurales a urbanos y evaluamos 2 hipótesis centrales para la planificación estratégica de la conservación: (1) declinaciones en el funcionamiento poblacional con el incremento de la dominancia humana y (2) las poblaciones pequeñas funcionan pobremente en relación con las grandes. La evaluación de estas hipótesis es crítica para la planificación estratégica de la conservación. El paradigma actual de la conservación se adhiere a la teoría ecológica bien establecida que propone que las poblaciones pequeñas aisladas, particularmente en paisajes dominados por humanos, tienen menor probabilidad de sobrevivir a largo plazo. Consecuentemente, la planificación de la conservación ha favorecido objetivos grandes y remotos. Este cambio hacia programas de conservación basados en ecosistemas y la protección de poblaciones en sistemas extensos y remotos ha sido a costa de la protección de las especies más raras entre las raras, el paradigma dominante en la conservación conducida por el acta de especies en peligro. No obstante, la evasión de la conservación de poblaciones pequeñas parece estar basada más en entendimiento teórico y en la opinión de expertos que en el empirismo. Utilizamos datos del Patrimonio Natural de California en una evaluación del funcionamiento de plantas raras en un paisaje con un gradiente urbano a rural. El funcionamiento de la población no decreció en sitios urbanos o en poblaciones que eran pequeñas inicialmente. Nuestros resultados son consistentes con un patrón de extinción de especies en estos paisajes en las últimas décadas. Concluimos que estas poblaciones en paisajes comprometidos pueden contribuir a la conservación de la biodiversidad en general. También argumentamos que la planificación de la conservación para la preservación de la biodiversidad debería asignar más recursos para la protección de taxa de plantas asociadas a ambientes urbanos porque pueden proporcionar beneficios de conservación más allá de simplemente proteger poblaciones aisladas; pueden ser útiles para construir el interés social por la conservación. [source]


A NEW METHOD FOR STUDYING THE EXTENT, STABILITY, AND PREDICTORS OF INDIVIDUAL SPECIALIZATION IN VIOLENCE,

CRIMINOLOGY, Issue 2 2007
D. WAYNE OSGOOD
Specialization in violence is an important scientific and policy topic, and over the past several decades, many analysis techniques for studying specialization have emerged. Research in this area continues to be hampered, however, by remaining methodological problems. To overcome these problems, we propose a new method for studying specialization in violence based on an item-response theory measurement approach that is implemented through a multilevel regression model. Our approach defines specialization as an individual level latent variable, takes into account the inherent confounds between specialization and overall level of offending, and gauges specialization relative to the population base rates of each offense. Our method also enables researchers to 1) estimate the extent and statistical significance of specialization, 2) assess the stability of specialization over time, and 3) relate specialization to explanatory variables. Using data from three studies, we found substantial levels of specialization in violence, considerable stability in specialization over time, and several significant and relatively consistent relationships of specialization to explanatory variables such as gender, parental education, and risk-seeking. [source]


Protein alterations in ESCC and clinical implications: a review

DISEASES OF THE ESOPHAGUS, Issue 1 2009
D.-C. Lin
SUMMARY Esophageal squamous cell carcinoma (ESCC) is the predominant histological subtype of esophageal cancer in Asia, characterized by high incidence and mortality rate. Although significant progress has been made in surgery and adjuvant chemoradiotherapy, the prognosis of the patients with this cancer still remains poor. Investigation into protein alterations that occurred in tumors can provide clues to discover new biomarkers for improving diagnosis and guiding targeted therapy. Hundreds of papers have appeared over the past several decades concerning protein alterations in ESCC. This review summarizes all the dysregulated proteins investigated in the disease from 187 published papers and analyzes their contributions to tumor development and progression. We document protein alterations associated with tumor metastasis and the transition from normal esophageal epithelia to dysplasia in order to reveal the most useful markers for prediction of clinical outcome, early detection, and identification of high-risk patients for targeted therapies. In particluar, we discuss the largest and most rigorous studies on prognostic implications of proteins in ESCC, in which cyclin D1, p53, E-cadherin and VEGF appeared to have the strongest evidence as independent predictors of patient outcome. [source]


The age-21 minimum legal drinking age: a case study linking past and current debates

ADDICTION, Issue 12 2009
Traci L. Toomey
ABSTRACT Background The minimum legal drinking age (MLDA) in the United States (U.S.) has raised debate over the past several decades. During the 1970s many states lowered their MLDAs from age 21 to 18, 19, or 20. However, as a result of studies showing that these lower MLDAs were associated with increases in traffic crashes, state-level movements began in the later1970s to return MLDAs to age 21. A new movement has arisen to again lower the MLDA in the U.S. Aim The aim is to discuss this current MLDA debate within the context of the long history of the U.S. MLDA. Methods A search of research articles, websites, and newspaper articles was conducted to identify key messages and influences related to the MLDA movements. Results The complexity of state movements to change their MLDAs is illustrated by the Michigan experience, where strong political forces on both sides of the issue were involved, resulting in the MLDA returning to 21. Because the 21st Constitutional amendment prevents the federal government from mandating a MLDA for all states, a federal policy was proposed to provide incentives for all states to implement age-21 MLDAs. Due largely to strong research evidence, the National Minimum Legal Drinking Age Act was enacted in 1984, stipulating that states set their MLDA to 21 or face loss of federal highway funds. By 1988, all states had an age-21 MLDA. Conclusion Any current debate about the MLDA should be informed by the historical context of this policy and the available research. [source]


Amphibian defenses against ultraviolet-B radiation

EVOLUTION AND DEVELOPMENT, Issue 1 2003
Andrew R. Blaustein
SUMMARY As part of an overall decline in biodiversity, amphibian populations throughout the world are disappearing. There are a number of potential causes for these declines, including those related to environmental changes such as increasing ultraviolet-B (UV-B) radiation due to stratospheric ozone depletion. UV-B radiation can kill amphibian embryos or can cause sublethal effects that can harm amphibians in later life stages. However, amphibians have defenses against UV-B damage that can limit damage or repair it after exposure to UV-B radiation. These include behavioral, physiological, and molecular defenses. These defenses differ interspecifically, with some species more able to cope with exposure to UV-B than others. Unfortunately, the defense mechanisms of many species may not be effective against increasing persistent levels of UV-B radiation that have only been present for the past several decades due to human-induced environmental damage. Moreover, we predict that persistent UV-B,induced mortality and sublethal damage in species without adequate defenses could lead to changes in community structure. In this article we review the effects of UV-B radiation on amphibians and the defenses they use to avoid solar radiation and make some predictions regarding community structure in light of interspecific differences in UV-B tolerance. [source]


Sclerotinia sclerotiorum: When "to be or not to be" a pathogen?

FEMS MICROBIOLOGY LETTERS, Issue 2 2005
Dwayne D. Hegedus
Abstract Sclerotinia sclerotiorum is unusual among necrotrophic pathogens in its requirement for senescent tissues to establish an infection and to complete the life cycle. A model for the infection process has emerged whereby the pathogenic phase is bounded by saprophytic phases; the distinction being that the dead tissues in the latter are generated by the actions of the pathogen. Initial colonization of dead tissue provides nutrients for pathogen establishment and resources to infect healthy plant tissue. The early pathogenicity stage involves production of oxalic acid and the expression of cell wall degrading enzymes, such as specific isoforms of polygalacturonase (SSPG1) and protease (ASPS), at the expanding edge of the lesion. Such activities release small molecules (oligo-galacturonides and peptides) that serve to induce the expression of a second wave of degradative enzymes that collectively bring about the total dissolution of the plant tissue. Oxalic acid and other metabolites and enzymes suppress host defences during the pathogenic phase, while other components initiate host cell death responses leading to the formation of necrotic tissue. The pathogenic phase is followed by a second saprophytic phase, the transition to which is effected by declining cAMP levels as glucose becomes available and further hydrolytic enzyme synthesis is repressed. Low cAMP levels and an acidic environment generated by the secretion of oxalic acid promote sclerotial development and completion of the life cycle. This review brings together histological, biochemical and molecular information gathered over the past several decades to develop this tri-phasic model for infection. In several instances, studies with Botrytis species are drawn upon for supplemental and supportive evidence for this model. In this process, we attempt to outline how the interplay between glucose levels, cAMP and ambient pH serves to coordinate the transition between these phases and dictate the biochemical and developmental events that define them. [source]


The murine allantois: emerging paradigms in development of the mammalian umbilical cord and its relation to the fetus

GENESIS: THE JOURNAL OF GENETICS AND DEVELOPMENT, Issue 5 2007
Kimberly E. Inman
Abstract The fertilized egg of the mammal gives rise to the embryo and its extraembryonic structures, all of which develop in intimate relation with each other. Yet, whilst the past several decades have witnessed a vast number of studies on the embryonic component of the conceptus, study of the extraembryonic tissues and their relation to the fetus have been largely ignored. The allantois, precursor tissue of the mature umbilical cord, is a universal feature of all placental mammals that establishes the vital vascular bridge between the fetus and its mother. The allantois differentiates into the umbilical blood vessels, which become secured onto the chorionic component of the placenta at one end and onto the fetus at the other. In this way, fetal blood is channeled through the umbilical cord for exchange with the mother. Despite the importance of this vascular bridge, little is known about how it is made. The aim of this review is to address current understanding of the biology of the allantois in the mouse and genetic control of its features and functions, and to highlight new paradigms concerning the developmental relationship between the fetus and its umbilical cord. genesis 45: 237,258, 2007. Published 2007 Wiley-Liss, Inc. [source]


Typologies of Advantage and Disadvantage: Socio-economic Outcomes in Australian Metropolitan Cities

GEOGRAPHICAL RESEARCH, Issue 4 2005
SCOTT BAUM
Abstract Australia's metropolitan cities have undergone significant social, economic and demographic change over the past several decades. In terms of socio-economic advantage and disadvantage these changes, which are often associated with globalisation, wider economic and technological restructuring, the changing demographics of the population and shifts in public policy are not evenly dispersed across cities, but represent a range of often contrasting outcomes. The current paper develops a typology of socio-economic advantage and disadvantage for locations across Australian metropolitan cities. More specifically, the paper takes a range of Australian Bureau of Statistics data and uses a model-based approach with clustering of data represented by a parameterised Gaussian mixture model and discriminant analysis utilised to consider the differences between the clusters. These clusters form the basis of a typology representing the range of socio-economic and demographic outcomes at the local community level. [source]


ASIANS IN AMERICA'S SUBURBS: PATTERNS AND CONSEQUENCES OF SETTLEMENT§

GEOGRAPHICAL REVIEW, Issue 2 2005
EMILY SKOP
ABSTRACT. In an effort to provide a more complex and multifaceted understanding of the process of spatial assimilation, this article explores alternative paths in understanding racial/ ethnic minority residential patterns. It scrutinizes patterns of contemporary Asian Indian and Chinese settlement in two metropolitan areas: Austin, Texas and Phoenix, Arizona. Though not particularly evolved in terms of their Asian immigrant settlement or dynamics, Austin and Phoenix represent the growing number of newly emergent Asian centers throughout the nation that have developed with the rapid rise of immigration from these two countries in the past several decades. The analysis utilizes records from the 2000 census to document and map Asian Indian and Chinese settlement within each metropolitan area and to investigate whether-and to what degree-each group is clustered or dispersed. The article then raises important questions about the consequences of concentration and dispersal for the incorporation of Asian Indian and Chinese residents. [source]


Cities, Skills, and Inequality

GROWTH AND CHANGE, Issue 3 2005
CHRISTOPHER H. WHEELER
ABSTRACT The surge in U.S. wage inequality over the past several decades is now commonly attributed to an increase in the returns paid to skill. Although theories differ with respect to why, specifically, this increase has come about, many agree that it is strongly tied to the increase in the relative supply of skilled (i.e., highly educated) workers in the U.S. labor market. A greater supply of skilled labor, for example, may have induced skill-biased technological change or generated greater stratification of workers by skill across firms or jobs. Given that metropolitan areas in the U.S. have long possessed more educated populations than non-metropolitan areas, these theories suggest that the rise in both the returns to skill and wage inequality should have been particularly pronounced in cities. Evidence from the U.S. Census over the period of 1950 to 1990 supports both implications. [source]


The medical visit context of treatment decision-making and the therapeutic relationship

HEALTH EXPECTATIONS, Issue 1 2000
Debra Roter Dr (Phil)
The ascendance of the autonomy paradigm in treatment decision-making has evolved over the past several decades to the point where few bioethicists would question that it is the guiding value driving health-care provider behaviour. In achieving quasi-legal status, decision-making has come to be regarded as a formality largely removed from the broader context of medical communication and the therapeutic relationship within which care is delivered. Moreover, disregard for individual patient preference, resistance, reluctance, or incompetence has at times produced pro forma and useless autonomy rituals. Failures of this kind, have been largely attributed to the psychological dynamics of the patients, physicians, illnesses, and contexts that characterize the medical decision. There has been little attempt to provide a framework for accommodating or understanding the larger social context and social influences that contribute to this variation. Applying Paulo Freire's participatory social orientation model to the context of the medical visit suggests a framework for viewing the impact of physicians' communication behaviours on patients' capacity for treatment decision-making. Physicians' use of communication strategies can act to reinforce an experience of patient dependence or self-reliance in regard to the patient-physician relationship generally and treatment decision-making, in particular. Certain communications enhance patient participation in the medical visit's dialogue, contribute to patient engagement in problem posing and problem-solving, and finally, facilitate patient confidence and competence to undertake autonomous action. The purpose of this essay is to place treatment decision-making within the broader context of the therapeutic relationship, and to describe ways in which routine medical visit communication can accommodate individual patient preferences and help develop and further patient capacity for autonomous decision-making. [source]


Decadal trend of climate in the Tibetan Plateau,regional temperature and precipitation

HYDROLOGICAL PROCESSES, Issue 16 2008
Z. X. Xu
Abstract The Tibetan Plateau has one of the most complex climates in the world. Analysis of the climate in this region is important for understanding the climate change worldwide. In this study, climate patterns and trends in the Tibetan Plateau were analysed for the period from 1961 to 2001. Air temperature and precipitation were analysed on monthly and annual time scales using data collected from the National Meteorological Centre, China Meteorological Administration. Nonlinear slopes were estimated and analysed to investigate the spatial and temporal trends of air temperature and precipitation in the Tibetan Plateau using a Mann,Kendall method. Spatial analysis of air temperature and precipitation variability across the Tibetan Plateau was undertaken. While most trends are local in nature, there are general basinwide patterns. Temperature during the last several decades showed a long-term warmer trend, especially the areas around Dingri and Zogong stations, which formed two increasing centres. Only one of the stations investigated exhibited decreasing trend, and this was not significant. Precipitation in the Tibetan Plateau has increased in most regions of the study area over the past several decades, especially in the eastern and central part, while the western Tibetan Region exhibited a decreased trend over the same period. Copyright © 2007 John Wiley & Sons, Ltd. [source]


A review on advances in alkali metal thermal to electric converters (AMTECs)

INTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 10 2009
Shuang-Ying Wu
Abstract The alkali metal thermal to electric converter (AMTEC) is one of the most promising technologies for direct conversion of thermal energy to electricity and has been receiving attention in the field of energy conversion and utilization in the past several decades. This paper aims to present a comprehensive review of the state of the art in the research and development of the AMTEC, including its working principles and types, historical development and applications, analytical models, working fluids, electrode materials, as well as the performance and efficiency improvement. The current two major problems encountered by the AMTEC, the time-dependent power degradation and relatively low efficiency compared to its theoretical value, are discussed in depth. In addition, a brief comparison of the AMTEC with other direct thermal to electric converters (DTECs), such as the thermoelectrics converter (TEC), thermionics converter, and thermophotovoltaics converter, is given, and combinations of different DTECs to further improve DTECs' power generation and overall conversion efficiency are demonstrated. Future research and development directions and the issues that need to be further investigated are also suggested. It is believed that this comprehensive review will be beneficial to the design, simulation, analysis, performance assessment, and applications of various types of AMTECs. Copyright © 2009 John Wiley & Sons, Ltd. [source]


Comparison of low temperature mixed refrigerant cycles for separation systems

INTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 4 2009
M. Mafi
Abstract Numerous mixed refrigerant cycles (MRCs) were developed in the past several decades in different applications. In this paper, two sets of low temperature MRCs are developed and simulated for a typical olefin plant utilizing a mixture of methane, ethane, propane and nitrogen as cycle working fluid to replace the pure ethylene refrigeration cycle that is used in conjunction with propylene refrigeration cycle in conventional plants. The key parameters of the cycles including mixture compositions and operating pressure levels are optimized to meet the objective of minimum shaftwork in compressor. The results show that different cycle configuration has different optimal mixture composition and low and high operating pressures. The results of exergy analysis reveal that the main location of the exergy loss in the cycles is the heat exchanger system. Also, the Carnot factor versus heat flow diagram is provided to identify the distribution of inefficiencies in the heat exchangers for each cycle. The simulation results show that MRCs can improve the thermodynamic performance of refrigeration system using the optimal working fluid mixture composition, optimal high and low operating pressures and optimal arrangement of the cycle components. Copyright © 2008 John Wiley & Sons, Ltd. [source]


Therapeutic Strategies for Xenograft Rejection

JOURNAL OF CARDIAC SURGERY, Issue 5 2001
Ph.D., Shu S. Lin M.D.
ABSTRACT The increasing demand for transplantable organs over the past several decades has stimulated the idea of using animal organs in lieu of cadaveric organs in clinical transplantation. Pigs are now considered to be the most suitable source of organs for transplantation because of their abundant availability, their appropriate size, their relatively short gestation period, and the recent development in the technology to genetically manipulate them. In the past few years, some of the seemingly complex immunologic responses in pig-to-primate transplantation have been elucidated. This progress has allowed us to focus our efforts on devising specific therapeutic strategies to overcome or prevent some of the responses that contribute to rejection of the xenograft. In this article, we review the various approaches that might allow clinical xenotransplantation to come to fruition. [source]


Mechanism of a plastic phenotypic response: predator-induced shell thickening in the intertidal gastropod Littorina obtusata

JOURNAL OF EVOLUTIONARY BIOLOGY, Issue 3 2007
J. I. BROOKES
Abstract Phenotypic plasticity has been the object of considerable interest over the past several decades, but in few cases are mechanisms underlying plastic responses well understood. For example, it is unclear whether predator-induced changes in gastropod shell morphology represent an active physiological response or a by-product of reduced feeding. We address this question by manipulating feeding and growth of intertidal snails, Littorina obtusata, using two approaches: (i) exposure to predation cues from green crabs Carcinus maenas and (ii) reduced food availability, and quantifying growth in shell length, shell mass, and body mass, as well as production of faecal material and shell micro-structural characteristics (mineralogy and organic fraction) after 96 days. We demonstrate that L. obtusata actively increases calcification rate in response to predation threat, and that this response entails energetic and developmental costs. That this induced response is not strictly tied to the animal's behaviour should enhance its evolutionary potential. [source]


Estimating price and income elasticities in the presence of age-cohort effects

AGRIBUSINESS : AN INTERNATIONAL JOURNAL, Issue 2 2006
Hiroshi Mori
Individual consumption of most food products varies by age, and in countries like Japan that have experienced drastic social and economic changes during the past several decades, it also differs from generation to generation. Unless proper measures are taken to account for these factors, estimates of demand elasticities could be severely biased. In this study, individual consumption of fresh fruit was derived from Japanese household data classified by age of household head for the years 1979,2001. Individual consumption was then decomposed by age, cohort, and period effects using Bayesian cohort analysis. Pure period effects thus determined were regressed against changes in price and income, to obtain less biased estimates for demand parameters than non- or partially age-compensated analysis. [Econlit citations: Q110]. © 2006 Wiley Periodicals, Inc. Agribusiness 22: 201,217, 2006. [source]


Business cycles in the euro area defined with coincident economic indicators and predicted with leading economic indicators

JOURNAL OF FORECASTING, Issue 1-2 2010
Ataman Ozyildirim
Abstract Clusters of cyclical turning points in the coincident indicators help us identify and date euro area recessions and recoveries in the past several decades. In the USA and some other countries, composite indexes of coincident indicators (CEI) are used to date classical business cycle turning points; also indexes of leading indicators (LEI) are used to help in the difficult task of predicting these turning points. This paper reviews a selection of the available data for monthly and quarterly euro area coincident and leading indicators. From these data, we develop composite indexes using methods analogous to those tested in the US CEI and LEI published by The Conference Board. We compare the resulting business cycle chronology with the existing alternatives and evaluate our selection of leading indicators in the context of how well they predict current economic activity and its major fluctuations for the euro area. Copyright © 2009 John Wiley & Sons, Ltd. [source]


Trade and agroindustrialization in developing countries: trends and policy impacts

AGRICULTURAL ECONOMICS, Issue 3 2000
Eugenio Díaz-Bonilla
Abstract There have been important changes in the international trade of processed and high-value added food products from developing countries over the past several decades. One of them has been the emergence of oilseeds and fruits and vegetables, replacing traditional products such as sugar, coffee, and cocoa as the main exports from developing countries. Another trend has been the collapse of African agroindustrial exports and the increase of exports from Asia. The paper highlights key trends, and explores possible reasons for the trends, focusing on trade policies in less-developed countries (LDCs) and developed countries (DCs). The paper argues that national trade policies and other economic policies appear to have been relatively supportive of agroindustrial production and exports in Asia. In contrast, policies have had more mixed effects in Latin America and the Caribbean (LAC), and seem to have been just one component in a larger array of forces inhibiting economic development in Africa. The performance of agroindustrial production and exports from LDCs may be now more dependent than ever on the completion of reforms in the agricultural trade policies of DCs. For Africa, however, a more supportive international environment and better macroeconomic and trade policies will not be enough to ensure a thriving agroindustrial sector within a broader process of economic development until military confrontations stop. [source]


Alcohol in Moderation, Cardioprotection, and Neuroprotection: Epidemiological Considerations and Mechanistic Studies

ALCOHOLISM, Issue 2 2009
Michael A. Collins
In contrast to many years of important research and clinical attention to the pathological effects of alcohol (ethanol) abuse, the past several decades have seen the publication of a number of peer-reviewed studies indicating the beneficial effects of light-moderate, nonbinge consumption of varied alcoholic beverages, as well as experimental demonstrations that moderate alcohol exposure can initiate typically cytoprotective mechanisms. A considerable body of epidemiology associates moderate alcohol consumption with significantly reduced risks of coronary heart disease and, albeit currently a less robust relationship, cerebrovascular (ischemic) stroke. Experimental studies with experimental rodent models and cultures (cardiac myocytes, endothelial cells) indicate that moderate alcohol exposure can promote anti-inflammatory processes involving adenosine receptors, protein kinase C (PKC), nitric oxide synthase, heat shock proteins, and others which could underlie cardioprotection. Also, brain functional comparisons between older moderate alcohol consumers and nondrinkers have received more recent epidemiological study. In over half of nearly 45 reports since the early 1990s, significantly reduced risks of cognitive loss or dementia in moderate, nonbinge consumers of alcohol (wine, beer, liquor) have been observed, whereas increased risk has been seen only in a few studies. Physiological explanations for the apparent CNS benefits of moderate consumption have invoked alcohol's cardiovascular and/or hematological effects, but there is also experimental evidence that moderate alcohol levels can exert direct "neuroprotective" actions,pertinent are several studies in vivo and rat brain organotypic cultures, in which antecedent or preconditioning exposure to moderate alcohol neuroprotects against ischemia, endotoxin, ,-amyloid, a toxic protein intimately associated with Alzheimer's, or gp120, the neuroinflammatory HIV-1 envelope protein. The alcohol-dependent neuroprotected state appears linked to activation of signal transduction processes potentially involving reactive oxygen species, several key protein kinases, and increased heat shock proteins. Thus to a certain extent, moderate alcohol exposure appears to trigger analogous mild stress-associated, anti-inflammatory mechanisms in the heart, vasculature, and brain that tend to promote cellular survival pathways. [source]


An improved method for determination of Holocene coastline changes around two ancient settlements in southern Anatolia: a geoarchaeological approach to historical land degradation studies

LAND DEGRADATION AND DEVELOPMENT, Issue 4 2003
Y. Bal
Abstract Two well-known ancient sites in southern Anatolia were selected to investigate and quantify the impact of historical land degradation on the Mediterranean coast of Turkey. These sites are the Luwian settlements of Kelenderis (modern Ayd,nc,k) and nearby Nagidos (Bozyaz,), both in Mersin Province and both occupied since around 4000,BP. Changes in local climatic conditions over this period have produced variations in the rates of fluvial transport of sediment/soil from the hinterland into the relevant deltaic regions, thus influencing rates of coastal progradation and aggradation. In addition, both eustatic and neotectonic movements have contributed to deltaic subsidence and/or hinterland uplift, with consequential impact on coastal evolution (positive or negative). The novel geoarchaeological methodology adopted in this study involves the creation of a graphical archive from detailed and standardised measurements taken from rectified mono- and stereoscopic aerial photographs. These archival data were then integrated with data from several types of historical map and field measurements in order to develop a geographical information system (GIS) database that could be interrogated, enabling graphical models of past coastal change to be constructed and calculations then made of the coastal configurations at successive historical periods. These calculations reveal that over the past 6000 years there has been only limited erosion/degradation in the karstic hinterland supplying the sediment to these two study sites (contrary to some previous statements concerning the high degradation risk of Mediterranean karst terrains). Furthermore, rates of progradation in each delta appear to have become diminished or even reversed in the past several decades as a result of both natural and anthropogenic factors. The precise contribution of neotectonic movements in this seismically active zone remains unquantified and is a topic requiring further interdisciplinary study. Copyright © 2003 John Wiley & Sons, Ltd. [source]


A Shakespearean Character on the Eighteenth-Century Stage: Recognizing Perdita

LITERATURE COMPASS (ELECTRONIC), Issue 4 2010
Emily Hodgson Anderson
Shakespeare's characters have always fascinated readers and viewers, yet for the past several decades ,character criticism' has been unpopular among Shakespearean scholars. Recently, although, ,character' has made a resurgence, especially in the context of performance studies. The 18th-century stage presents a good venue from within which to examine this new critical approach, as 18th-century audiences were enamored both with Shakespeare's plays and the offstage lives of the actors they came to see. Building from this fact, this essay examines the influence of the actor/role relationship on popular theories of characterization; in particular, it focuses on the actress Mary Robinson and the character of Perdita. By asking what it meant for audiences to recognize Robinson as ,Perdita', and ,Perdita' as Mary Robinson, the essay provides one example of how attention to performance history can enrich our analysis of Shakespearean characters today. [source]


A primer on classical test theory and item response theory for assessments in medical education

MEDICAL EDUCATION, Issue 1 2010
André F De Champlain
Context, A test score is a number which purportedly reflects a candidate's proficiency in some clearly defined knowledge or skill domain. A test theory model is necessary to help us better understand the relationship that exists between the observed (or actual) score on an examination and the underlying proficiency in the domain, which is generally unobserved. Common test theory models include classical test theory (CTT) and item response theory (IRT). The widespread use of IRT models over the past several decades attests to their importance in the development and analysis of assessments in medical education. Item response theory models are used for a host of purposes, including item analysis, test form assembly and equating. Although helpful in many circumstances, IRT models make fairly strong assumptions and are mathematically much more complex than CTT models. Consequently, there are instances in which it might be more appropriate to use CTT, especially when common assumptions of IRT cannot be readily met, or in more local settings, such as those that may characterise many medical school examinations. Objectives, The objective of this paper is to provide an overview of both CTT and IRT to the practitioner involved in the development and scoring of medical education assessments. Methods, The tenets of CCT and IRT are initially described. Then, main uses of both models in test development and psychometric activities are illustrated via several practical examples. Finally, general recommendations pertaining to the use of each model in practice are outlined. Discussion, Classical test theory and IRT are widely used to address measurement-related issues that arise from commonly used assessments in medical education, including multiple-choice examinations, objective structured clinical examinations, ward ratings and workplace evaluations. The present paper provides an introduction to these models and how they can be applied to answer common assessment questions. Medical Education 2010: 44: 109,117 [source]


The promise of technology for college instruction: From drill and practice to avatars

NEW DIRECTIONS FOR TEACHING & LEARNING, Issue 123 2010
Sally Kuhlenschmidt
Technology and its uses have undergone significant change in the past several decades. Technology has many benefits and it has impacted many of the ways that teaching and learning occur. However, the role of thoughtful consideration, selection, implementation, and assessment of the technology remains the ultimate responsibility of the teacher. [source]


Culture theorizing past and present: trends and challenges

NURSING PHILOSOPHY, Issue 4 2010
Helen E.R. Vandenberg RN MSc (Nursing)
Abstract Over the past several decades, nurses have been increasingly theorizing about the relationships between culture, health, and nursing practice. This culture theorizing has changed over time and has recently been subject to much critical examination. The purpose of this paper is to identify the challenges impeding nurses' ability to build theory about the relationships between culture and health. Through a historical overview, I argue that continued support for the essentialist view of culture can maintain a limited view of complex race relations. I also argue that attempts to apply culture theory, without knowledge of important historical, political, and economic factors, has often resulted in oversimplified versions of what was originally intended. Furthermore, I argue that individual-level interventions alone will be insufficient to address health inequities related to culture. Despite new critical conceptualizations of culture and the uptake of cultural safety, nursing scholars must better address the broader organizational, population, and political interventions needed to address inequities in health. I conclude with suggestions for how nurses might proceed with culture theorizing given these challenges. [source]


Breakfast Frequency and Quality in the Etiology of Adult Obesity and Chronic Diseases

NUTRITION REVIEWS, Issue 6 2007
Maureen T. Timlin PhD
The frequency of eating breakfast has declined over the past several decades, during which time the obesity epidemic has also unfolded. Therefore, there is growing scientific interest in the possible causal role of breakfast in weight control and related disease risks. We conducted a MedLine search for studies that addressed meal frequency, breakfast consumption, and chronic disease risk. Clinical studies document that regular meal consumption can potentially reduce the risk of obesity and chronic disease through mechanisms involved in energy balance and metabolism. Many observational studies have found that breakfast frequency is inversely associated with obesity and chronic disease, but this literature does have some important limitations. Only four relatively small and short-term randomized trials have examined breakfast consumption and body weight or chronic disease risk, with mixed results. Large, long-term, randomized trials are needed. [source]


Pulmonary arterial hypertension in children

PEDIATRIC PULMONOLOGY, Issue 1 2004
Erika Berman Rosenzweig MD
Abstract Pulmonary arterial hypertension is a serious progressive condition with a poor prognosis if not identified and treated early. Because the symptoms are nonspecific and the physical findings can be subtle, the disease is often diagnosed in its later stages. Remarkable progress has been made in the field of pulmonary arterial hypertension over the past several decades. The pathology is now better defined, and significant advances have occurred in understanding the pathobiologic mechanisms. Risk factors have been identified, and the genetics have been characterized. Advances in technology allow earlier diagnosis as well as better assessment of disease severity. Therapeutic modalities such as new drugs, e.g., epoprostenol, treprostinil, and bosentan, and surgical/interventional options, e.g., transplantation and atrial septostomy, which were unavailable several decades ago, have had a significant impact on prognosis and outcome. Thus, despite our inability to cure pulmonary arterial hypertension, advances in medical treatments over the past two decades have resulted in significant improvement in outcomes for children with various forms of pulmonary arterial hypertension. This report is a review the current state of the art for pulmonary arterial hypertension in 2004, with an emphasis on childhood pulmonary arterial hypertension and specific recommendations for current practice and future directions. Pediatr Pulmonol. 2004; 38:2,22. © 2004 Wiley-Liss, Inc. [source]


Trends in suspected and recognized occupational respiratory diseases in Germany between 1970 and 2005

AMERICAN JOURNAL OF INDUSTRIAL MEDICINE, Issue 7 2008
V. van Kampen PhD
Abstract Background Respiratory diseases represent a major proportion of occupational diseases in many countries. Little information is available about their incidences over the past several decades. Methods Based on the reports of the three German federal accident insurance agencies, the numbers of suspected and recognized cases of occupational respiratory diseases between 1970 and 2005 were collected and combined. The trends in the rates per 100,000 insured workers were calculated. Results In total, a decline in occupational respiratory diseases since 1998 could be observed. This trend is mainly based on the decrease in non-malignant respiratory diseases due to silica and obstructive airway diseases. In contrast, asbestos-induced diseases showed a leveling off or an increase (mesothelioma) during the last 10years. Conclusions Although trends in occupational disease may be influenced by several factors, the presented data indicate that prevention has been effective in reducing some ofthe most frequent occupational respiratory diseases in Germany. Am. J. Ind. Med. 51:492,502, 2008. © 2008 Wiley-Liss, Inc. [source]


Abortion, Family Planning, and Population Policy: Prospects for the Common-Ground Approach

POPULATION AND DEVELOPMENT REVIEW, Issue 3 2009
Dennis Hodgson
For the past several decades those engaged in shaping the Program of Action documents at international conferences on population have muted their voices when the topic of abortion has been raised. In a desire to side-step entanglement in a bitter debate over the morality of abortion, great care has been taken to define "family planning" in ways that explicitly exclude abortion. The "common-ground" approach to treating abortion can be summarized in two directives found in all contemporary international population documents: "in no case should abortion be promoted as a method of family planning"; and all governments should work "to reduce the recourse to abortion through expanded and improved family-planning services." This article has three goals: first, to examine the appropriateness of these directives with respect to what is currently known about the relationship between abortion, family planning, and population policy; second, to trace how this "contraception-only" definition of family planning became de rigueur at international population conferences; and third, to discuss the prospects for the emergence of a more appropriate "common-ground" approach to abortion and population policy. [source]


Intergenerational Coresidence in Developing Countries

POPULATION AND DEVELOPMENT REVIEW, Issue 2 2008
Steven Ruggles
Newly available census microdata from IPUMS-International are used to assess trends in intergenerational coresidence in 15 developing countries. Contrary to expectations, we find no general decline in intergenerational coresidence over the past several decades. There have been, however, significant changes in the configuration of intergenerational coresidence. Families in which a member of the older generation is household head,a configuration consistent with traditional patriarchal forms in which the older generation retains authority,are becoming more common in most of the countries. Intergenerational families headed by a member of the younger generation,the configuration one would expect if intergenerational coresidence were motivated by a need for old-age support,are on the decline in most of the countries. Multivariate analysis reveals that intergenerational families headed by the older generation are positively associated with measures of economic development. These findings are at variance with widely accepted social theory. We hypothesize that housing shortages, economic stress in the younger generation, and old-age pensions may contribute to the change. More broadly, in some developing countries rising incomes may have allowed more people to achieve their preferred family structure of intergenerational coresidence following traditional family forms. [source]