10,559 research outputs found

    Can the Type-IIB axion prevent Pre-big Bang inflation?

    Get PDF
    We look at the possibility of superinflationary behavior in a class of anisotropic Type-IIB superstring cosmologies in the context of Pre-big Bang scenario and find that there exists a rather narrow range of parameters for which these models inflate. We then show that, although in general this behavior is left untouched by the introduction of a Ramond-Ramond axion field through a SL(2,R) rotation, there exists a particular class of axions for which inflation disappears completely. Asymptotic past initial conditions are briefly discussed, and some speculations on the possible extension of Pre-big Bang ideas to gravitational collapse are presented.Comment: harvmac, epsf. 3 figures include

    Beyond sex allocation: the role of mating systems in sexual selection in parasitoid wasps

    Get PDF
    Despite the diverse array of mating systems and life histories which characterise the parasitic Hymenoptera,sexual selection and sexual conict in this taxon have been somewhat overlooked. For instance, parasitoidmating systems have typically been studied in terms of how mating structure affects sex allocation. In thepast decade, however, some studies have sought to address sexual selection in the parasitoid wasps moreexplicitly and found that, despite the lack of obvious secondary sexual traits, sexual selection has the potentialto shape a range of aspects of parasitoid reproductive behaviour and ecology. Moreover, various characteristicsfundamental to the parasitoid way of life may provide innovative new ways to investigate different processesof sexual selection. The overall aim of this review therefore is to re-examine parasitoid biology with sexualselection in mind, for both parasitoid biologists and also researchers interested in sexual selection and theevolution of mating systems more generally. We will consider aspects of particular relevance that have alreadybeen well studied including local mating structure, sex allocation and sperm depletion. We go on to review whatwe already know about sexual selection in the parasitoid wasps and highlight areas which may prove fruitfulfor further investigation. In particular, sperm depletion and the costs of inbreeding under chromosomal sexdetermination provide novel opportunities for testing the role of direct and indirect benets for the evolutionof mate choice

    Cosmological solutions in the brane-bulk system

    Full text link
    In this work we find cosmological solutions in the brane-bulk system starting from a 5-D line element which is a simple extension, for cosmological applications, of the pioneering Randall-Sundrum line element. From the knowledge of the bulk metric, assumed to have the form of plane waves propagating in the fifth dimension, we solve the corresponding 4-D Einstein equations on the brane with a well defined energy-momentum tensor.Comment: 14 pages, revtex4, comments adde

    The rationality of Sol manifolds

    Get PDF
    Let Γ\Gamma be the fundamental group of a manifold modeled on three dimensional Sol geometry. We prove that Γ\Gamma has a finite index subgroup GG which has a rational growth series with respect to a natural generating set. We do this by enumerating GG by a regular language. However, in contrast to most earlier proofs of this sort our regular language is not a language of words in the generating set, but rather reflects a different geometric structure in GG.Comment: 30 pages; author's name changed to agree with published version; to appear in Journal of Algebr

    Improving Communication between Doctors and Parents after Newborn Screening

    Get PDF
    Background: Newborn screening (NBS) enables early treatment, and some consider it a natural vehicle for genetic screening. Bioethicists argue for caution since families of infants with carrier status can develop psychosocial complications. This paper describes the methods and feasibility of Wisconsin’s statewide project for quality improvement of communication and psychosocial outcomes after NBS. Methods: When NBS identifies carrier status for cystic fibrosis or sickle cell, we contact primary care providers (PCPs), answer questions, and invite them to rehearse informing the parents. Three months later, we telephone the parents, assess knowledge and psychosocial outcomes, provide counseling, and assist with self-referral to further resources. Afterward, evaluation surveys are provided to the parents, to be returned anonymously. Results: Birthing facilities provided accurate PCP names for 73% of 817 infants meeting inclusion criteria; we identified PCPs for 21% more. We reached 47.3% of PCPs in time to invite a rehearsal; 60% of these accepted. We successfully called 50.2% of eligible parents; 61% recalled a PCP explanation, and 48.5% evaluated the explanation favorably. Evaluations by parents with limited health literacy were less favorable. Conclusion: It is feasible to follow parents for psychosocial outcomes after NBS. Preliminary data about communication is mixed, but further data will describe psychosocial outcomes and investigate outcomes’ associations with communication

    A Method to Assess the Organizing Behaviors Used in Physicians\u27 Counseling of Standardized Parents after Newborn Genetic Screening

    Get PDF
    Well-organized conversation can improve people’s ability to comprehend and retain information. As part of a long-term effort to adapt Quality Improvement techniques for communication, we developed an explicit criteria method to assess usage of three organizing behaviors (OBs): ‘opening behaviors’ to establish goals; ‘structuring behaviors’ to guide patients through conversation; and ‘emphasizing behaviors’ that signal a need for attention. Pairs of abstractors independently reviewed transcripts in a demonstration sample of conversations between physicians and standardized parents after newborn screening identifies carrier status for sickle cell disease. Criteria for at least one OB were identified in 50/84 transcripts (60%), including 27 with at least one opening behavior (32%), 5 with at least one structuring behavior (6%), and 38 with at least one emphasizing behavior (45%). The limited number of OBs raises concern about communication after newborn screening. Assessment and improvement of OB usage may improve understanding and allow parents to more actively participate in health care

    Sector level cost of equity in African financial markets

    Get PDF
    This paper assesses the effectiveness of Liu (2006) metrics in measuring illiquidity within a multifactor CAPM pricing model. Costs of equity are estimated using this model for the major sectors within Africa’s larger equity markets: Morocco, Tunisia, Egypt, Kenya, Nigeria, Zambia, Botswana and South Africa. In all countries, the cost of equity is found to be highest in the financial sector and lowest in the blue chip stocks of Tunisia, Morocco, Namibia and South Africa. At an aggregate level, Nigeria and Zambia have the highest cost of capital

    Adult attachment style across individuals and role-relationships: Avoidance is relationship-specific, but anxiety shows greater generalizability

    Get PDF
    A generalisability study examined the hypotheses that avoidant attachment, reflecting the representation of others, should be more relationship-specific (vary across relationships more than across individuals), while attachment anxiety, reflecting self-representation, should be more generalisable across a person’s relationships. College students responded to 6-item questionnaire measures of these variables for 5 relationships (mother, father, best same-gender friend, romantic partner or best opposite-gender friend, other close person), on 3 (N = 120) or 2 (N = 77) occasions separated by a few weeks. Results supported the hypotheses, with the person variance component being larger than the relationship-specific component for anxiety, and the opposite happening for avoidance. Anxiety therefore seems not to be as relationship-specific as previous research suggested. Possible reasons for discrepancies between the current and previous studies are discussed

    Morphology of the canine omentum, part 1: arterial landmarks that define the omentum

    Get PDF
    Although the omentum remains an enigmatic organ, research during the last decades has revealed its fascinating functions including fat storage, fluid drainage, immune activity, angiogenesis and adhesion. While clinicians both in human and veterinary medicine are continuously exploring new potential omental applications, detailed anatomical data on the canine omentum are currently lacking, and information is often retrieved from human medicine. In this study, the topographic anatomy of the canine greater and lesser omentum is explored in depth. Current nomenclature is challenged, and a more detailed terminology is proposed. Consistent arteries that are contained within folds of the superficial omental wall are documented, described and named, as they can provide the anatomical landmarks that are necessary for unambiguous scientific communication on the canine omentum. In an included dissection video, the conclusions and in situ findings described in this study are demonstrated
    corecore