1,074 research outputs found

    Reconciling Grand Unification with Strings by Anisotropic Compactifications

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    We analyze gauge coupling unification in the context of heterotic strings on anisotropic orbifolds. This construction is very much analogous to effective 5 dimensional orbifold GUT field theories. Our analysis assumes three fundamental scales, the string scale, \mstring, a compactification scale, \mc, and a mass scale for some of the vector-like exotics, \mex; the other exotics are assumed to get mass at \mstring. In the particular models analyzed, we show that gauge coupling unification is not possible with \mex = \mc and in fact we require \mex \ll \mc \sim 3 \times 10^{16} GeV. We find that about 10% of the parameter space has a proton lifetime (from dimension 6 gauge exchange) 1033yrτ(pπ0e+)1036yr10^{33} {\rm yr} \lesssim\tau(p\to \pi^0e^+) \lesssim 10^{36} {\rm yr}. The other 80% of the parameter space gives proton lifetimes below Super-K bounds. The next generation of proton decay experiments should be sensitive to the remaining parameter space.Comment: 36 pages and 5 figures, contains some new references and additional paragraph in conclusio

    Magistrate Raby Confidentiality Order

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    A solution to the mu problem in the presence of a heavy gluino LSP

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    In this paper we present a solution to the μ\mu problem in an SO(10) supersymmetric grand unified model with gauge mediated and D-term supersymmetry breaking. A Peccei-Quinn symmetry is broken at the messenger scale M1012M\sim 10^{12} GeV and enables the generation of the μ\mu term. The boundary conditions defined at MM lead to a phenomenologically acceptable version of the minimal supersymmetric standard model with novel particle phenomenology. Either the gluino or the gravitino is the lightest supersymmetric particle (LSP). If the gravitino is the LSP, then the gluino is the next-to-LSP (NLSP) with a lifetime on the order of one month or longer. In either case this heavy gluino, with mass in the range 25 - 35 GeV, can be treated as a stable particle with respect to experiments at high energy accelerators. Given the extensive phenomenological constraints we show that the model can only survive in a narrow region of parameter space resulting in a light neutral Higgs with mass 8691\sim 86 - 91 GeV and tanβ914\tan\beta \sim 9 - 14. In addition the lightest stop and neutralino have mass 100122\sim 100 - 122 GeV and 5072\sim 50 - 72 GeV, respectively. Thus the model will soon be tested. Finally, the invisible axion resulting from PQ symmetry breaking is a cold dark matter candidate.Comment: 30 pages, 9 figure

    Preparing and Developing Community College International Leaders

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    Leadership training for future senior United States (US) community college leaders is an ongoing focus of US community college education. Leadership training is also a focus of US university international educators. Community college literature has assumed that full-time positions at community colleges devoted to overseeing and implementing internationalization do not exist and thus have not addressed succession opportunities. Based on a survey of 91 individuals who self-define their positions as ones in community college international leadership, this article examines what influences shaped the professional paths of these individuals and depicts criteria that can support future preparation for community college international education leadership from the viewpoint of those currently working in these positions. Pathway development patterns are seen in three forms: a) traditional preparation; b) non-traditional preparation; and c) job-embedded professional development

    Can multi-TeV (top and other) squarks be natural in gauge mediation?

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    We investigate whether multi-TeV (1-3 TeV) squarks can be natural in models of gauge mediated SUSY breaking. The idea is that for some boundary condition of the scalar (Higgs and stop) masses, the Higgs (mass)2^2, evaluated at the renormalization scale O(100)\sim O(100) GeV, is not very sensitive to (boundary values of) the scalar masses (this has been called ``focussing'' in recent literature). Then, the stop masses can be multi-TeV without leading to fine-tuning in electroweak symmetry breaking. {\em Minimal} gauge mediation does {\em not} lead to this focussing (for all values of tanβ\tan \beta and the messenger scale): the (boundary value of) the Higgs mass is too small compared to the stop masses. Also, in minimal gauge mediation, the gaugino masses are of the same order as the scalar masses so that multi-TeV scalars implies multi-TeV gauginos (especially gluino) leading to fine-tuning. We discuss ideas to {\em increase} the Higgs mass relative to the stop masses (so that focussing can be achieved) and also to {\em suppress} gaugino masses relative to scalar masses (or to modify the gaugino mass relations) in {\em non-minimal} models of gauge mediation -- then multi-TeV (top and other) squarks can be natural. Specific models of gauge mediation which incorporate these ideas and thus have squarks (and in some cases, the gluino) heavier than a TeV without resulting in fine-tuning are also studied and their collider signals are contrasted with those of other models which have multi-TeV squarks.Comment: LaTeX, 29 pages, 9 eps figures. Replacing an earlier version. In version 3, some references and a minor comment have been added and typos have been correcte

    SO(10) SUSY GUT for Fermion Masses : Lepton Flavor and CP Violation

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    We discuss the results of a global χ2\chi^2 analysis of a simple SO(10) SUSY GUT with D3D_3 family symmetry and low energy R parity. The model describes fermion mass matrices with 14 parameters and gives excellent fits to 20 observable masses and mixing angles in both quark and lepton sectors, giving 6 predictions. Bi-large neutrino mixing is obtained with hierarchical quark and lepton Yukawa matrices; thus avoiding the possibility of large lepton flavor violation. The model naturally predicts small 1-3 neutrino mixing, with sinθ130.050.06\sin \theta_{13} \simeq 0.05 - 0.06. In this paper we evaluate the predictions for the lepton flavor violating processes, μeγ\mu \to e \gamma, τμγ\tau \to \mu \gamma and τeγ\tau \to e \gamma and also the electric dipole moment of the electron, ded_e, muon and tau, assuming universal squark and slepton masses, m16m_{16}, and a universal soft SUSY breaking A parameter, A0A_0, at the GUT scale. We find Br(μeγ)Br(\mu \to e \gamma) is naturally below present bounds, but may be observable by MEG. Similarly, ded_e is below present bounds; but is within the range of future experiments. We also give predictions for the light Higgs mass (using FeynHiggs). We find an upper bound given by mh127m_h \leq 127 GeV, with an estimated ±3\pm 3 GeV theoretical uncertainty. Finally we present predictions for SUSY particle masses in the favored region of parameter space.Comment: 25 pages, 18 figures, several typos in captions of tables 2 and 3 corrected, acknowledgments adde

    Issues of alcohol misuse among older people : attitudes and experiences of social work practitioners

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    This small-scale qualitative research focused on the experiences of social workers vis--vis older people who misuse alcohol. Based in an Older People's Team in the west of Scotland, the study explored service provision for alcohol misuse and examined whether practitioners felt the existing services provided by the Substance Misuse Team were effective in meeting the needs of older people with an alcohol problem. Using semi-structured interviews, data were collected from 18 participants, the majority (14) of whom were female and whose ages ranged from 31 to 54 years. Several key themes emerged including the extent of alcohol problems among older people and the complex reasons that cause older people to misuse alcohol. These reasons commonly related to the increasing challenges of old age. The data also demonstrated that current services are not meeting the needs of older people. Practitioners identified a need for an 'age-specific' approach to target more effectively the complex needs of older people. Recommendations from practitioners included ways to develop new and more effective services, including a more age-specific service, such as providing longer term support in older people's own homes, using a specialised support worker, and increasing staff training on alcohol use among older people

    Modal testing of offshore rock lighthouses around the British Isles

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    EURODYN 2017, 2017-09-10, 2017-09-13, RomeThis is the author accepted manuscript. The final version is available from the publisher via the DOI in this record.Given that 95 per cent of the UK’s international trade is transported by sea, and as a vital complement to fallible virtual navigational aids such as GPS, rock-mounted lighthouses constructed in the 19th century have a crucial role to play in safe navigation. However the longevity of these historical structures is threatened by extreme weather so in the UK, the General Lighthouse Authorities comprising Trinity House, the Northern Lighthouse Board and the Commissioners of Irish Lights are supporting three British universities in a program of linked experimental and analytical investigations of full-scale performance under extreme wave loading. The aim is to use structural models calibrated by modal testing to deduce wave loading from response recorded by long-term monitoring. The paper describes the procedures for modal testing, taking into account the constraints on access, logistics, unfamiliar layout and time. The test program sequentially covered Les Hanois, Wolf Rock, Longships and Bishops Rock lighthouses over summer 2016 followed by Fastnet Rock in December 2016. Some conventional techniques of forced and ambient vibration testing were used along with some unusual excitation methods. Results from the measurements and observations on the particular challenges associated with testing two of these iconic structures are presented.The research was funded by EPSRC grant EP/N022955/

    Implications of the 2011 Great East Japan Tsunami on sea defence design

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    After the 2004 Boxing Day tsunami, much of the world's effort to defend against tsunami concentrated on tsunami warning and evacuation. The 2011 Great East Japan Earthquake and Tsunami led to direct and indirect losses as well as the deaths of many vulnerable members of Japan's coastal communities. This event has resulted in Japan rethinking and revising its design codes for sea defence structures. The new guidance emerging from this process is a valuable resource for other countries re-evaluating their own current mitigation strategies and this paper presents details of this process. The paper starts with the history of sea defence design standards in Japan and explains the process of revision of design guidelines since 2011. Examples of sea defences that failed and have since been rebuilt, observed during the two Earthquake Engineering Field Investigation Team (EEFIT) missions of 2011 and 2013, are also presented. The paper concludes with a discussion of international approaches and their application to nuclear power stations in Japan and the UK

    Mechanisms of airway epithelial injury and abnormal repair in asthma and COPD

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    The airway epithelium comprises of different cell types and acts as a physical barrier preventing pathogens, including inhaled particles and microbes, from entering the lungs. Goblet cells and submucosal glands produce mucus that traps pathogens, which are expelled from the respiratory tract by ciliated cells. Basal cells act as progenitor cells, differentiating into different epithelial cell types, to maintain homeostasis following injury. Adherens and tight junctions between cells maintain the epithelial barrier function and regulate the movement of molecules across it. In this review we discuss how abnormal epithelial structure and function, caused by chronic injury and abnormal repair, drives airway disease and specifically asthma and chronic obstructive pulmonary disease (COPD). In both diseases, inhaled allergens, pollutants and microbes disrupt junctional complexes and promote cell death, impairing the barrier function and leading to increased penetration of pathogens and a constant airway immune response. In asthma, the inflammatory response precipitates the epithelial injury and drives abnormal basal cell differentiation. This leads to reduced ciliated cells, goblet cell hyperplasia and increased epithelial mesenchymal transition, which contribute to impaired mucociliary clearance and airway remodelling. In COPD, chronic oxidative stress and inflammation trigger premature epithelial cell senescence, which contributes to loss of epithelial integrity and airway inflammation and remodelling. Increased numbers of basal cells showing deregulated differentiation, contributes to ciliary dysfunction and mucous hyperproduction in COPD airways. Defective antioxidant, antiviral and damage repair mechanisms, possibly due to genetic or epigenetic factors, may confer susceptibility to airway epithelial dysfunction in these diseases. The current evidence suggests that a constant cycle of injury and abnormal repair of the epithelium drives chronic airway inflammation and remodelling in asthma and COPD. Mechanistic understanding of injury susceptibility and damage response may lead to improved therapies for these diseases
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