4,943 research outputs found
LOADS: a computer program for determining the shear, bending moment and axial loads for fuselage type structures
LOADS determines rigid body vehicle shears, bending moments and axial loads on a space vehicle due to aerodynamic loads and propellant inertial loads. An example hand calculation is presented and was used to check LOADS. A brief description of the program and the equations used are presented. LOADS is operational on the Univac 1110, occupies 10505 core and typically takes less than one(1) second of CAU time to execute
Evolutionary genetic analysis of an invasive population of sculpins in the Lower Rhine
Fish abundance surveys have shown that the Lower Rhine was invaded by sculpins (Cottus sp.) within two decades. These fish are found in habitats that are untypical for Cottus gobio. In order to find source populations and reasons for this invasion an evolutionary genetic analysis of populations from the Rhine and surrounding rivers was conducted. A combined analysis of nuclear and mitochondrial markers suggests that invasive sculpins are hybrids between lineages from the Rivers Scheldt and Rhine. The hybrids form a distinct genetic group and possess a unique ecological potential, attributed here to the process of hybridization. To explore the genetics of invasive sculpins 177 microsatellite markers were developed and a linkage map for Cottus was constructed from F1 crosses. BLAST searches with microsatellite flanking sequences yield significant hits with the Tetraodon nigroviridis genomic sequence for 45% of the Cottus loci. Comparisons of the map locations between the genomes reveal extensive conserved synteny, suggesting that the Tetraodon genomic sequence will serve as an excellent reference for Cottus. The novel markers and linkage information are applied in population genetic studies and to initiate first QTL approaches. Evidence that invasive sculpins have a unique ecological potential to colonize large rivers is derived from recently formed hybrid zones where secondary contact postdates the appearance of invasive sculpins in the early 1990's. Hybrid zones are moulded by exogenous selection in the absence of intrinsic reproductive barriers. Hybridization receives attention because of the role that it may play in generating evolutionary novelty, which is tested in recent hybrids. Body shape is analysed with a new distance based assignment method using morphometric data. Shape is highly informative in that populations are sufficiently different to assign 'unknowns' to their source. Recent hybrids are intermediate between parental groups but display additional differentiation. This suggests transgressive segregation and genetic divergence in developmental processes underlying body shape. Natural hybrid zones offer an alternative for QTL mapping because far-reaching associations between states of ancestry at physically linked loci are generated in segregating hybrids. Ancestry association is exploited by admixture mapping, which is applied for the first time in wild populations. The Cottus genome was screened for association with morphological characters as well as with habitat as a surrogate of ecological differentiation. Candidate regions often affect more than one trait. This implies linkage of traits affecting divergent morphology and fitness. Selection at hybrid zones likely affects linked morphological traits. Likewise, the differentiation of invasive sculpins despite past hybridization could be explained by linkage of morphological with adaptive traits
Radical relations in orthogonal groups
AbstractAny relation between simple isometries is a consequence of relations of lengths â©˝4. This extends earlier results which deal with relations between reflections
Bireflectionality of the weak orthogonal and the weak symplectic groups
Digitalitzat per Artypla
Mach's Principle and Model for a Broken Symmetric Theory of Gravity
We investigate spontaneous symmetry breaking in a conformally invariant
gravitational model. In particular, we use a conformally invariant scalar
tensor theory as the vacuum sector of a gravitational model to examine the idea
that gravitational coupling may be the result of a spontaneous symmetry
breaking. In this model matter is taken to be coupled with a metric which is
different but conformally related to the metric appearing explicitly in the
vacuum sector. We show that after the spontaneous symmetry breaking the
resulting theory is consistent with Mach's principle in the sense that inertial
masses of particles have variable configurations in a cosmological context.
Moreover, our analysis allows to construct a mechanism in which the resulting
large vacuum energy density relaxes during evolution of the universe.Comment: 9 pages, no figure
Shape based assignment tests suggest transgressive phenotypes in natural sculpin hybrids (Teleostei, Scorpaeniformes, Cottidae)
BACKGROUND: Hybridization receives attention because of the potential role that it may play in generating evolutionary novelty. An explanation for the emergence of novel phenotypes is given by transgressive segregation, which, if frequent, would imply an important evolutionary role for hybridization. This process is still rarely studied in natural populations as samples of recent hybrids and their parental populations are needed. Further, the detection of transgressive segregation requires phenotypes that can be easily quantified and analysed. We analyse variability in body shape of divergent populations of European sculpins (Cottus gobio complex) as well as natural hybrids among them. RESULTS: A distance-based method is developed to assign unknown specimens to known groups based on morphometric data. Apparently, body shape represents a highly informative set of characters that parallels the discriminatory power of microsatellite markers in our study system. Populations of sculpins are distinct and "unknown" specimens can be correctly assigned to their source population based on body shape. Recent hybrids are intermediate along the axes separating their parental groups but display additional differentiation that is unique and coupled with the hybrid genetic background. CONCLUSION: There is a specific hybrid shape component in natural sculpin hybrids that can be best explained by transgressive segregation. This inference of how hybrids differ from their ancestors provides basic information for future evolutionary studies. Furthermore, our approach may serve to assign candidate specimens to their source populations based on morphometric data and help in the interpretation of population differentiation
The Impact of Problem-Based Learning (PBL) on Training and Practice in Clinical Psychology
This is a pre-publication version of the following article: Pieter W. Nel, David Novelli & Lizette Nolte, 'The impact of problem-based learning on training and practice in clinical psychology', Clinical Psychology Forum, Number 294, June 2017, available online at: https://shop.bps.org.uk/publications/publication-by-series/clinical-psychology-forum/clinical-psychology-forum-no-294-june-2017.html. Published by the British Psychological Society.This study investigated the impact of Problem-Based Learning (PBL) on the training and professional practice of clinical psychologists, using a mixed method design. The findings suggest that PBL is experienced by trainees as an effective method of learning in clinical psychology.Peer reviewe
Negotiating motherhood as a refugee: Experiences of loss, love, survival and pain in the context of forced migration
This document is the Accepted Manuscript version of an article published by Taylor & Francis in European Journal of Psychotherapy & Counselling on September 2016, available online at: http://www.tandfonline.com/doi/full/10.1080/13642537.2016.1214160 © 2016 Informa UK Limited, trading as Taylor & Francis GroupThe mental health of refugees has been an increasingly-researched area, but has been criticised for having an individualised and symptom-focused approach to understanding the experience of forced migration. This paper attempts to respond to calls to address this culturally limited and incomplete way of conceptualising responses to experiences of persecution and terror bound up within global hegemony and power inequalities. Interpretative phenomenological analysis (IPA) was employed to analyse semi-structured interviews undertaken with six refugee mothers, with the aim of exploring how participants made sense of, and created meaning around parenting and family life in the UK. Three main themes emerged from the data analysis (a) loss as a constant companion to parenting; (b) a shifting view of the self as a mother; and (c) taking the good with the bad in family life. Methodological limitations, as well as implications for future research and clinical practice are discussed.Peer reviewe
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