1,983 research outputs found

    Higgs Boson Exempt No-Scale Supersymmetry with a Neutrino Seesaw: Implications for Lepton Flavor Violation and Leptogenesis

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    Motivated by the observation of neutrino oscillations, we extend the Higgs boson exempt no-scale supersymmetry model (HENS) by adding three heavy right-handed neutrino chiral supermultiplets to generate the light neutrino masses and mixings. The neutrino Yukawa couplings can induce new lepton flavor violating couplings among the soft terms in the course of renormalization group running down from the boundary scale. We study the effects this has on the predictions for low-energy probes of lepton flavor violation(LFV). Heavy right-handed neutrinos also provide a way to generate the baryon asymmetry through leptogenesis. We find that consistency with LFV and leptogenesis puts strong requirements on either the form of the Yukawa mass matrix or the smallness of the Higgs up soft mass. In all cases, we generically expect that new physics LFV is non-zero and can be found in a future experiment.Comment: 25 pages, 11 figures; Added a referenc

    Introducing SEARCHBreast: a virtual resource to facilitate sharing of surplus animal material developed for breast cancer research

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    Animals studies have made significant contribution to expanding our knowledge of breast cancer. Often material is leftover and archived. SEARCHBreast provides a platform for collaborative sharing of archived material via a dedicated on-line database whereby users can both share and search available tissue. The SEARCHBreast database has information on over 50 different mouse models, including tissue from PDX models, available to share. With thousands of samples freely available, SEARCHBreast should be the first point of call for any researcher looking for animal material to aid their breast cancer research

    SEARCHBreast: a new resource to locate and share surplus archival material from breast cancer animal models to help address the 3Rs

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    Animal models have contributed to our understanding of breast cancer, with publication of results in high-impact journals almost invariably requiring extensive in vivo experimentation. As such, many laboratories hold large collections of surplus animal material, with only a fraction being used in publications relating to the original projects. Despite being developed at considerable cost, this material is an invisible and hence an underutilised resource, which often ends up being discarded. Within the breast cancer research community there is both a need and desire to make this valuable material available for researchers. Lack of a coordinated system for visualisation and localisation of this has prevented progress. To fulfil this unmet need, we have developed a novel initiative called Sharing Experimental Animal Resources: Coordinating Holdings—Breast (SEARCHBreast) which facilitates sharing of archival tissue between researchers on a collaborative basis and, de facto will reduce overall usage of animal models in breast cancer research. A secure searchable database has been developed where researchers can find, share, or upload materials related to animal models of breast cancer, including genetic and transplant models. SEARCHBreast is a virtual compendium where the physical material remains with the original laboratory. A bioanalysis pipeline is being developed for the analysis of transcriptomics data associated with mouse models, allowing comparative study with human and cell line data. Additionally, SEARCHBreast is committed to promoting the use of humanised breast tissue models as replacement alternatives to animals. Access to this unique resource is freely available to all academic researchers following registration at https://searchbreast.org

    The SEARCHBreast portal: A virtual bioresource to facilitate the sharing of surplus animal materials derived from breast cancer studies

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    The SEARCHBreast portal (https://searchbreast.org/) provides access to a virtual bioresource enabling researchers to access and share material derived from breast cancer related animal studies on a collaborative basis. By registering as members of SEARCHBreast, researchers can browse the SEARCHBreast platform for relevant tissue and models, and request access to these to help answer their specific biological question(s). SEARCHBreast mediates the collaborations formed from requests for these materials. As of July 2016, the virtual bioresource has received 8 requests for tissue and has sent hundreds of tissue samples saving approximately 400 animals. SEARCHBreast is currently developing a bioinformatics pipeline, enabling users to access and mine published data on animal models of breast cancer, potentially helping to reduce experimental redundancy further, prioritising new relevant research

    Isotopic distribution of fission fragments in collisions between 238U beam and 9Be and 12C targets at 24 MeV/u

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    Inverse kinematics coupled to a high-resolution spectrometer is used to investigate the isotopic yields of fission fragments produced in reactions between a 238U beam at 24 MeV/u and 9Be and 12C targets. Mass, atomic number and isotopic distributions are reported for the two reactions. These informations give access to the neutron excess and the isotopic distribution widths, which together with the atomic-number and mass distributions are used to investigate the fusion-fission dynamics.Comment: Submitted to PR

    Dynamics and Instabilities of Planar Tensile Cracks in Heterogeneous Media

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    The dynamics of tensile crack fronts restricted to advance in a plane are studied. In an ideal linear elastic medium, a propagating mode along the crack front with a velocity slightly less than the Rayleigh wave velocity, is found to exist. But the dependence of the effective fracture toughness Γ(v)\Gamma(v) on the crack velocity is shown to destabilize the crack front if (dΓ)/(dv)<0(d\Gamma)/(dv)<0. Short wavelength radiation due to weak random heterogeneities leads to this instability at low velocities. The implications of these results for the crack dynamics are discussed.Comment: 12 page

    Multivariate analysis of morphology, behaviour, growth and developmental timing in hybrids brings new insights into the divergence of sympatric Arctic charr morphs

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    This work was fully funded by the Icelandic Centre of Research, RANNÍS (Icelandic Research Fund grant no.173802-051).Background: Studying the development of fitness related traits in hybrids from populations diverging in sympatry is a fundamental approach to understand the processes of speciation. However, such traits are often affected by covariance structures that complicate the comprehension of these processes, especially because the interactive relationships between traits of different nature (e.g. morphology, behaviour, life-history) remain largely unknown in this context. In a common garden setup, we conducted an extensive examination of a large suit of traits putatively involved in the divergence of two morphs of Arctic charr (Salvelinus alpinus), and investigated the consequences of potential patterns of trait covariance on the phenotype of their hybrids. These traits were measured along ontogeny and involved growth, yolk sac resorption, developmental timing (hatching and the onset of exogeneous feeding), head morphology and feeding behaviour. Results: Growth trajectories provided the strongest signal of phenotypic divergence between the two charr. Strikingly, the first-generation hybrids did not show intermediate nor delayed growth but were similar to the smallest morph, suggesting parental biases in the inheritance of growth patterns. However, we did not observe extensive multivariate trait differences  between the two morphs and their hybrids. Growth was linked to head morphology (suggesting that morphological variations in early juveniles relate to simple allometric effects) but this was the only strong signal of covariance observed between all the measured traits. Furthermore, we did not report evidence for differences in overall phenotypic variance between morphs, nor for enhanced phenotypic variability in their hybrids. Conclusion: Our study shed light on the multivariate aspect of development in a context of adaptive divergence. The lack of evidence for the integration of most traits into a single covariance structure suggested that phenotypic constraints may not always favour nor impede divergence toward ecological niches differing in numerous physical and ecological variables, as observed in the respective habitats of the two charr. Likewise, the role of hybridization as a disruptive agent of trait covariance may not necessarily be significant in the evolution of populations undergoing resource polymorphism.Publisher PDFPeer reviewe

    Crack Front Waves and the dynamics of a rapidly moving crack

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    Crack front waves are localized waves that propagate along the leading edge of a crack. They are generated by the interaction of a crack with a localized material inhomogeneity. We show that front waves are nonlinear entities that transport energy, generate surface structure and lead to localized velocity fluctuations. Their existence locally imparts inertia, which is not incorporated in current theories of fracture, to initially "massless" cracks. This, coupled to crack instabilities, yields both inhomogeneity and scaling behavior within fracture surface structure.Comment: Embedded Latex file including 4 figure
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