Home About us Contact
|
Home About us Contact | ||
|
|
||
Many Circumstances (many + circumstance)
Selected AbstractsPARENTS BENEFIT FROM EATING OFFSPRING: DENSITY-DEPENDENT EGG SURVIVORSHIP COMPENSATES FOR FILIAL CANNIBALISMEVOLUTION, Issue 10 2006Hope Klug Abstract Why should animals knowingly consume their own young? It is difficult to imagine many circumstances in which eating one's own young (i.e., filial cannibalism) actually increases an individual's fitness; however, filial cannibalism commonly co-occurs with parental care in fishes. The evolutionary significance of filial cannibalism remains unclear. The most commonly accepted explanation is that filial cannibalism is a mechanism by which caring males gain energy or nutrients that they reinvest into future reproduction, thereby increasing net reproductive success. There is mixed support for this hypothesis and, at best, it can only explain filial cannibalism in some species. A recent alternative hypothesis suggests that filial cannibalism improves the survivorship of remaining eggs by increasing oxygen availability, and thus increases current reproductive success. This theory has received little attention as of yet. We evaluated the hypothesis of oxygen-mediated filial cannibalism in the sand goby by examining the effect of oxygen and egg density on the occurrence of filial cannibalism, evaluating the effects of partial clutch cannibalism on the survivorship of remaining eggs, and comparing potential costs and benefits of filial cannibalism related to the net number of eggs surviving. Indeed, we found that oxygen level and egg density affected the occurrence of cannibalism and that simulated partial clutch cannibalism improved survivorship of the remaining eggs. Additionally, because increased egg survivorship, stemming from partial egg removal, compensated for the cost of cannibalism (i.e., number of eggs removed) at a range of cannibalism levels, filial cannibalism potentially results in no net losses in reproductive success. However, oxygen did not affect egg survivorship. Thus, we suggest a more general hypothesis of filial cannibalism mediated by density-dependent egg survivorship. [source] Informative-Transmission Disequilibrium Test (i-TDT): combined linkage and association mapping that includes unaffected offspring as well as affected offspringGENETIC EPIDEMIOLOGY, Issue 2 2007Chao-Yu Guo Abstract To date, there is no test valid for the composite null hypothesis of no linkage or no association that utilizes transmission information from heterozygous parents to their unaffected offspring as well as the affected offspring from ascertained nuclear families. Since the unaffected siblings also provide information about linkage and association, we introduce a new strategy called the informative-transmission disequilibrium test (i-TDT), which uses transmission information from heterozygous parents to all of the affected and unaffected offspring in ascertained nuclear families and provides a valid chi-square test for both linkage and association. The i-TDT can be used in various study designs and can accommodate all types of independent nuclear families with at least one affected offspring. We show that the transmission/disequilibrium test (TDT) (Spielman et al. [1993] Am. J. Hum. Genet. 52:506,516) is a special case of the i-TDT, if the study sample contains only case-parent trios. If the sample contains only affected and unaffected offspring without parental genotypes, the i-TDT is equivalent to the sibship disequilibrium test (SDT) (Horvath and Laird [1998] Am. J. Hum. Genet. 63:1886,1897. In addition, the test statistic of i-TDT is simple, explicit and can be implemented easily without intensive computing. Through computer simulations, we demonstrate that power of the i-TDT can be higher in many circumstances compared to a method that uses affected offspring only. Applying the i-TDT to the Framingham Heart Study data, we found that the apolipoprotein E (APOE) gene is significantly linked and associated with cross-sectional measures and longitudinal changes in total cholesterol. Genet. Epidemiol. © 2006 Wiley-Liss, Inc. [source] Review of the Integrated Groundwater and Surface-Water Model (IGSM)GROUND WATER, Issue 2 2003Eric M. LaBolle Development of the finite-element-based Integrated Groundwater and Surface-Water Model (IGSM) began in the 1970s. Its popularity grew in the early 1990s with its application to California's Central Valley Groundwater Surface-Water Model in support of the Central Valley Project Improvement Act. Since that time, IGSM has been applied by federal, state, and local agencies to model a number of major basins in California. Our review of the recently released version 5.0 of IGSM reveals a solution methodology that deviates from established solution techniques, potentially compromising its reliability under many circumstances. One difficulty occurs because of the semi-explicit time discretization used. Combined with the fixed monthly time step of IGSM, this approach can prevent applications from accurately converging when using parameter values typically found in nature. Additionally, IGSM fails to properly couple and simultaneously solve ground water and surface water models with appropriate mass balance and head convergence under the reasonable conditions considered herein. As a result, IGSM-predicted streamflow is error prone, and errors could exceed 100%. IGSM does not inform the user that there may be a convergence problem with the solution, but instead generally reports good mass balance. Although our review touches on only a few aspects of the code, which exceeds 17,000 lines, our experience is that similar problems arise in other parts of IGSM. Review and examples demonstrate the potential consequences of using the solution methods in IGSM for the prediction, planning, and management of water resources, and provide perspective on the roles of standards and code validation in ground water modeling. [source] Search strategies in decision making: the success of "success"JOURNAL OF BEHAVIORAL DECISION MAKING, Issue 2 2004Ben R. Newell Abstract Examination of search strategies has tended to focus on choices determined by decision makers' personal preferences among relevant cues, and not on learning cue-criterion relationships. We present an empirical and rational analysis of cue search for environments with objective criteria. In such environments, cues can be evaluated on the basis of three properties: validity (the probability that a cue identifies the correct choice if cue values differ between alternatives); discrimination rate (the proportion of occasions on which a cue has differing values); and success (the expected proportion of correct choices when only that cue can be used). Our experiments show that though there is a high degree of individual variability, success is a key determinant of search. Furthermore, a rational analysis demonstrates why success-directed search is the most adaptive strategy in many circumstances. Copyright © 2004 John Wiley & Sons, Ltd. [source] Clear cell sarcoma of soft tissue: diagnostic utility of fluorescence in situ hybridization and reverse transcriptase polymerase chain reactionJOURNAL OF CUTANEOUS PATHOLOGY, Issue 4 2008Choladda V. Curry A 7-year-old girl presented with pain and progressive swelling on the left plantar surface. Biopsy of a 2.5 cm mass showed nests of large round to oval neoplastic cells with abundant amphophilic to clear cytoplasm, prominent nucleoli and high mitotic activity. Occasional cells showed spindled morphology. Infrequent melanin pigment was present. Melanocytic markers (HMB45, S-100) were diffusely positive. A diagnosis of clear cell sarcoma of soft tissue (CCSS) was made, and the mass was re-excised with negative margins. 28 months later, a 1.0 cm pulmonary nodule was identified and wedge excision showed metastatic CCSS. Cytogenetics showed a complex karyotype (unbalanced translocation der(12;14)(q10;q10), additional chromosome 22 material of unknown origin). Although the CCSS translocation t(12;22)(q13;q12) was not identified, EWSR1 gene rearrangement was detected by fluorescence in situ hybridization (FISH). Reverse transcription polymerase chain reaction (RT-PCR) showed an EWS-ATF1 fusion transcript, confirmed by direct sequencing. CCSS requires differentiation from malignant melanoma, because of overlapping clinical presentations, sites of involvement, histomorphology, immunocytochemical profiles and ultrastructure. In many circumstances, definitive diagnosis is only possible with confirmation of the CCSS-defining translocation. [source] Clear Cell Sarcoma of Soft Tissue with Cytogenetic and Molecular AnalysesJOURNAL OF CUTANEOUS PATHOLOGY, Issue 1 2006C. Vejabhuti A 7-year-old girl presented with pain and progressive swelling on the left plantar surface. Biopsy of a 2.5 cm mass demonstrated nests of large oval tumor cells with high nuclear-to-cytoplasm ratio, amphophilic to clear cytoplasm, prominent nucleoli, and brisk mitotic activity. Occasional cells showed spindled morphology. Infrequent melanin pigment was present. Melanocytic markers (HMB45, S-100) were diffusely positive. A diagnosis of clear cell sarcoma of soft tissue (CCSS) was made, and the tumor was re-excision with negative margins. 28 months later, a 1.0 cm pulmonary nodule was identified and showed CCSS. Cytogenetics demonstrated a complex karyotype (unbalanced translocation der(12;14)(p10;q10), additional chromosome 22 material of unknown origin). Although the CCSS translocation t(12;22)(q13;q12) was not identified, EWSR1 gene rearrangement was detected by fluorescence in situ hybridization (FISH). RT-PCR demonstrated an EWS-ATF1 fusion transcript, confirmed by direct sequencing. CCSS requires differentiation from malignant melanoma, due to overlapping clinical presentations, sites of involvement, histomorphology, immunocytochemical profiles, and ultrastructure. In many circumstances, definitive diagnosis is only possible with confirmation of the CCSS tumor-defining translocation. [source] A primer on classical test theory and item response theory for assessments in medical educationMEDICAL EDUCATION, Issue 1 2010André 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] HOW TO PREDICT FUTURE DURATION FROM PRESENT AGETHE PHILOSOPHICAL QUARTERLY, Issue 222 2006Bradley Monton The physicist J. Richard Gott has given an argument which, if good, allows one to make accurate predictions for the future longevity of a process, based solely on its present age. We show that there are problems with some of the details of Gott's argument, but we defend the core thesis: in many circumstances, the greater the present age of a process, the more likely a longer future duration. [source] Front and Back Covers, Volume 24, Number 4.ANTHROPOLOGY TODAY, Issue 4 2008August 200 Front cover and back cover caption, volume 24 issue 4 Front cover Front cover: Front cover The front cover of this issue illustrates Vasiliki P. Neofotistos' article on the 2006 film Borat: Cultural learnings of America for make benefit glorious nation of Kazakhstan. In the film, British comedian Sacha Baron Cohen plays Borat Sagdiyev, a Kazakh journalist, who leaves his country on a project funded by the Ministry of Information to travel with his film producer to ,US and A, the greatest country in the world' and make a ,movie film' about American culture, with the putative aim of gaining insights into what makes America great and applying them to Kazakhstan. The film has generated contrasting reactions, ranging from CNN's praise of it as ,most excellent comedy' to lawsuits filed by, among others, residents of the Romanian village in which part of the film was shot. Borat has been condemned as deeply offensive to women, Kazakhs, fraternity brothers and Jews alike. In this issue Neofotistos focuses on some of the lessons that Western audiences could potentially take away from the film, using the notion of the grotesque as a tool to read Borat as an allegory of America that invites us to revisit aspects of our own culture and hence as a highly appropriate film for our times. Back cover Back cover: ,FORTRESS' SOUTH AFRICA? A South African and a foreigner find common ground in Islam. The two men are about to enter a mosque in downtown Pretoria for Friday prayers. Prayers at this mosque provide a meeting ground for Muslim men and women from all over Africa, and from Pakistan, India, Bangladesh and Afghanistan. Foreigners attending the mosque range from diplomats to illegal immigrants. Significant numbers of black South Africans from all walks of life have converted to Islam in recent years. In this issue John Sharp shows that there are many circumstances in which - as in this photograph - South Africans and foreigners from elsewhere in Africa pursue shared interests peacefully. Anthropological field research points to the range of these contexts, which have largely been ignored by commentators attempting to explain the episode of mass ,xenophobic' violence that wracked South African cities and towns in May 2008. Explanations focus on the xenophobic attitudes of ordinary South Africans, and link these attitudes to competition for resources between locals who are poor and their equally poor counterparts from further north. Recent research indicates, however, not only that relationships between poor South Africans and poor foreigners are more complex than most commentators allow, but also that South African xenophobia begins at the top, among the leaders of the ANC government and the black and white elites whose interests it serves. Sharp argues that a newly-issued report on the xenophobic violence by a government-orientated think tank reproduces the dominant xenophobic discourse in its recommendation that the state should construct a ,Fortress SA' with impenetrable borders, while seeking to mask its adherence to official discourse by representing its proposals as a response to the xenophobic attitudes of poor South Africans. As Sharp suggests, anthropological research might offer a more nuanced response to the issues. [source] ,Fortress SA': Xenophobic violence in South AfricaANTHROPOLOGY TODAY, Issue 4 2008John Sharp There are many circumstances in which South Africans and foreigners from elsewhere in Africa pursue shared interests peacefully. Anthropological field research points to a range of these circumstances, which have largely been ignored by commentators attempting to explain the episode of mass,xenophobic'violence that wracked South African cities and towns in May 2008. Explanations such as the one criticised in this article focus on the xenophobic attitudes of ordinary South Africans, and link these attitudes to competition for resources between locals who are poor and their equally poor counterparts from further north. Recent research indicates, however, not only that relationships between poor South Africans and poor foreigners are more complex than most commentators allow, but also that South African xenophobia begins at the top, among the leaders of the ANC government and the black and white elites whose interests it serves. This article argues that a newly-issued report on the xenophobic violence by a government-orientated think tank reproduces the dominant xenophobic discourse in its recommendation that the state should construct a,Fortress SA'with impenetrable borders. Yet this report seeks to mask its adherence to official discourse by representing its proposals as a response to the xenophobic attitudes of poor South Africans. [source] Measuring producer welfare under output price uncertainty and risk non-neutralityAUSTRALIAN JOURNAL OF AGRICULTURAL & RESOURCE ECONOMICS, Issue 1 2005David S. Bullock Procedures to measure the producer welfare effects of changes in an output price distribution under uncertainty are reviewed. Theory and numerical integration methods are combined to show how for any form of Marshallian risk-responsive supply, compensating variation of a change in higher moments of an output price distribution can be derived numerically. The numerical procedure enables measurement of producer welfare effects in the many circumstances in which risk and uncertainty are important elements. The practical ease and potential usefulness of the procedure is illustrated by measuring the producer welfare effects of USA rice policy. [source] | |||||||||||||||||||