Growth, current size and the role of the 'reversal paradox' in the foetal origins of adult disease: an illustration using vector geometry

BACKGROUND Numerous studies have reported inverse associations between birth weight and a range of diseases in later life. These have led to the development of the 'foetal origins of adult disease hypothesis'. However, many such studies have only been able to demonstrate a statistically significant association between birth weight and disease in later life by adjusting for current size. This has been interpreted as evidence that the impact of low birth weight on subsequent disease is somehow dependent on subsequent weight gain, and has led to a broadening of the hypothesis into the 'developmental origins of health and disease'. Unfortunately, much of the epidemiological evidence used for both of these interpretations is prone to a statistical artefact known as the 'reversal paradox'. The aim of this paper is to illustrate why, using vector geometry. MATERIALS AND METHODS This paper introduces the key concepts of vector geometry as applied to multiple regression analysis. This approach is then used to illustrate the similar statistical problems encountered when adjusting for current size or growth when exploring the association between birth weight and disease in later life. RESULTS Geometrically, the three covariates – birth size, growth, and current size – span only 2-dimensional space. Regressing disease in later life (i.e. the outcome variable) on any two of these covariates equates to projecting the disease variable onto the plane spanned by the three covariate vectors. The three possible regression models – where any two covariates are considered – are therefore equivalent and yield exactly the same model fit (R2). CONCLUSION Vector geometry illustrates why it is impossible to differentiate between the effects of growth from the effects of current size in studies exploring the relationship between size at birth and subsequent disease. For similar reasons, it is impossible to differentiate between the effects of growth and the effects of birth weight. Assessing the 'independent' impact of growth on later disease by adjusting for either birth weight or current size is therefore illusory

Methods for structural design at elevated temperatures

A procedure which can be used to design elevated temperature structures is discussed. The desired goal is to have the same confidence in the structural integrity at elevated temperature as the factor of safety gives on mechanical loads at room temperature. Methods of design and analysis for creep, creep rupture, and creep buckling are presented. Example problems are included to illustrate the analytical methods. Creep data for some common structural materials are presented. Appendix B is description, user's manual, and listing for the creep analysis program. The program predicts time to a given creep or to creep rupture for a material subjected to a specified stress-temperature-time spectrum. Fatigue at elevated temperature is discussed. Methods of analysis for high stress-low cycle fatigue, fatigue below the creep range, and fatigue in the creep range are included. The interaction of thermal fatigue and mechanical loads is considered, and a detailed approach to fatigue analysis is given for structures operating below the creep range

Social research for a multiethnic population: do the research ethics and standards guidelines of UK Learned Societies address this challenge?

There is increasing recognition in the UK that social science research should generate an evidence base that reflects the ethnic diversity of the population and informs positive developments in public policy and programmes for all. However, describing and understanding ethnic diversity, and associated disadvantage, is far from straightforward. In practice, the ethical and scientific arguments around whether and how to incorporate ethnicity into policy-relevant social research are complex and contentious. In particular, untheorised or insensitive inclusion of data on ethnic 'groups' can have negative consequences. The present investigation begins to explore the extent to which social scientists have access to advice and guidance in this area of research. Specifically, the paper examines how ethnic diversity is explicitly or implicitly considered within the research ethics and scientific standard guidance provided by UK social science Learned Societies to their members. The review found little in the way of explicit attention to ethnic diversity in the guidance documents, but nevertheless identified a number of pertinent themes. The paper compiles and extrapolates these themes to present a tentative set of principles for social scientists to debate and further develop

Existence, Uniqueness and Stability of Solutions of a Class of Nonlinear Partial Differential Equations

In this work we present a unified approach for treating the existence, uniqueness and asymptotic stability of classical solutions for a class of nonlinear partial differential equations governing the behavior of nonlinear continuous dynamical systems

Laying the Groundwork for the TTI Impact Study: Purposes, Values, Concepts

This document is part of an ongoing cycle of writing and comment designed to help us imagine forward into the work of the new Scholarship and Tenure Policy Research Group (TTI-RG). Here we aim to set a tone, to create an ethos, and to begin to craft a shared language for participants. Our process, therefore, both models and seeks to inform the processes of policy change. We want to set before the Fellows a more precise framing of our principles and purposes. If the initial dialogues among the Fellows and organizational partners can establish agreement on the larger purposes and guiding concepts of our work, we will do a better job of establishing the impact of IA\u27s Tenure Team Initiative on Public Scholarship (TTI), and our subsequent recommendations will carry more force. We report here on the groundwork that we have been preparing since the planning for the Research Group, initially categorized as a TTI-RG, began in October 2010. We suggest principles and strategies that, refined through further conversation, should guide the research. Above all, we propose that the TTI-RG assess faculty rewards systems as dynamic elements in the larger set of co-dependent relationships among (1) diverse, engaged student bodies; (2) diverse, engaged faculties; and (3) diverse, engaged communities

Intersection Information based on Common Randomness

The introduction of the partial information decomposition generated a flurry of proposals for defining an intersection information that quantifies how much of "the same information" two or more random variables specify about a target random variable. As of yet, none is wholly satisfactory. A palatable measure of intersection information would provide a principled way to quantify slippery concepts, such as synergy. Here, we introduce an intersection information measure based on the G\'acs-K\"orner common random variable that is the first to satisfy the coveted target monotonicity property. Our measure is imperfect, too, and we suggest directions for improvement.Comment: 19 pages, 5 figure

Mining non-model genomic libraries for microsatellites: BAC versus EST libraries and the generation of allelic richness

<p>Abstract</p> <p>Background</p> <p>Simple sequence repeats (SSRs) are tandemly repeated sequence motifs common in genomic nucleotide sequence that often harbor significant variation in repeat number. Frequently used as molecular markers, SSRs are increasingly identified via <it>in silico </it>approaches. Two common classes of genomic resources that can be mined are bacterial artificial chromosome (BAC) libraries and expressed sequence tag (EST) libraries.</p> <p>Results</p> <p>288 SSR loci were screened in the rapidly radiating Hawaiian swordtail cricket genus <it>Laupala</it>. SSRs were more densely distributed and contained longer repeat structures in BAC library-derived sequence than in EST library-derived sequence, although neither repeat density nor length was exceptionally elevated despite the relatively large genome size of <it>Laupala</it>. A non-random distribution favoring AT-rich SSRs was observed. Allelic diversity of SSRs was positively correlated with repeat length and was generally higher in AT-rich repeat motifs.</p> <p>Conclusion</p> <p>The first large-scale survey of Orthopteran SSR allelic diversity is presented. Selection contributes more strongly to the size and density distributions of SSR loci derived from EST library sequence than from BAC library sequence, although all SSRs likely are subject to similar physical and structural constraints, such as slippage of DNA replication machinery, that may generate increased allelic diversity in AT-rich sequence motifs. Although <it>in silico </it>approaches work well for SSR locus identification in both EST and BAC libraries, BAC library sequence and AT-rich repeat motifs are generally superior SSR development resources for most applications.</p

The Availability of Training Opportunities in Personality Disorders in American Psychological Association- and Psychological Clinical Science Accreditation System-Accredited Clinical and Counseling Psychology Doctoral Programs

Personality disorders are relatively common, especially in clinical settings. A number of evidence-based treatments are now available, especially for borderline personality disorder. However, little is known about the relevant training available to doctoral students in clinical and counseling psychology. in the current study, data were extracted from 336 clinical and counseling Ph.D. and Psy.D. programs from the Insider’s Guide to Graduate Programs in Clinical and Counseling Psychology (Norcross & Sayette, 2020), including the number of programs with faculty with specific interests in personality disorders and the number of programs with clinical opportunities related to personality disorders. We found that formal training in personality disorders is not widely available to most trainees in APA-accredited doctoral training programs. Only 16% of programs have faculty with interests in personality disorders, all of them clinical psychology programs. Ph.D. programs were more likely to have PD-interested faculty than Psy.D. programs, and, within clinical Ph.D. programs, PCSAS-accredited programs were more likely to have PD-interested faculty than programs without PCSAS accreditation. Similarly, only 15% of programs (all clinical psychology programs) offer practicum opportunities in psychotherapy for personality disorders. Our findings indicate that doctoral level psychology programs are not sufficiently preparing their students with personality disorder training, which serves as a substantial disservice to both trainees and the public

Covert visual search within and beyond the effective oculomotor range

Covert spatial attention is tightly coupled to the eye-movement system, but the precise nature of this coupling remains contentious. Recent research has argued that covert attention and overt eye-movements many share a common biological limit, such that covert exogenous orienting of attention is limited to stimuli that fall within the range of possible eye movements (the effective oculomotor range: EOMR). However, this conclusion is based on a single experimental paradigm: The Posner cueing task. Here, we examine the extent to which covert spatial attention is limited to the EOMR in visual search. Exogenous attention was assessed using a feature search task and endogenous attention assessed using a conjunction search task. The tasks were performed monocularly with the dominant eye in the frontal position or abducted by 40°. In the abducted position stimuli in the temporal hemispace could be seen, but could not become the goal of a saccadic eye-movement (i.e. they were beyond the EOMR). In contrast, stimuli in the nasal hemifield remained within the EOMR. We observed a significant effect of eye-abduction on feature search, such that search was slower when targets appeared beyond the EOMR. In contrast, eye-abduction had no effect on search times during conjunction search. Set size did not interact with target location or eye-position. It is concluded that optimal covert orienting of exogenous attention in visual search is restricted to locations within the effective oculomotor range