1,063 research outputs found

    6D supergravity without tensor multiplets

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    We systematically investigate the finite set of possible gauge groups and matter content for N = 1 supergravity theories in six dimensions with no tensor multiplets, focusing on nonabelian gauge groups which are a product of SU(N) factors. We identify a number of models which obey all known low-energy consistency conditions, but which have no known string theory realization. Many of these models contain novel matter representations, suggesting possible new string theory constructions. Many of the most exotic matter structures arise in models which precisely saturate the gravitational anomaly bound on the number of hypermultiplets. Such models have a rigid symmetry structure, in the sense that there are no moduli which leave the full gauge group unbroken.Comment: 31 pages, latex; v2, v3: minor corrections, references adde

    Seasonal Changes in Sleep, RPE, and Scoring Percentage in Division One Collegiate Female Basketball Players

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    Basketball season occurs over several months and involves heavy traveling, training, competing, and scholarly duties. These demands do not allow much time for rest and recovery. A lack in the quantity and quality of sleep can reduce the ability to manage stress and reduce recovery from training and competition. This can affect the health and well-being of the athlete and their success on the court. In college, sleep schedules may change from high school by staying up later and sleeping in more. College students typically sleep between six and seven hours a night which is less than the recommended nine hours (Eaton, 2007). The question appears to be whether a lack of sleep influences perceived exertion during training, competition and performance. There have been many studies examining the relationship between sleep hygiene and illness but less on performance (Damien, 2007). Twelve female basketball athletes recorded the number of hours of sleep, RPE following practice, and scoring percentage every day for six weeks. Statistical analysis was conducted to note difference in RPE, sleep, and scoring percentage. There was no significant difference in all variables across the six weeks of the in-season

    Positive Attitudes as a Mediator Between Moral Disengagement and Cyberbullying Behaviors

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    Objective. The current study examined whether (1) higher moral disengagement scores would be positively correlated with higher frequencies of engaging in cyberbullying, (2) positive attitude scores would be positively correlated with higher frequencies of engaging in cyberbullying, and (3) positive attitudes towards cyberbullying would mediate links between moral disengagement and frequency of engaging in cyberbullying. Method. Three surveys, the Mechanisms of Moral Disengagement Scale (MMD), Cyberbullying Perpetration Measure (CPM), and Positive Attitudes towards Cyberbullying Questionnaire (PATC) were administered to 114 undergraduate students. Results. Correlational analysis indicated significant positive correlations between PATC and CPM scores (r = .442, p \u3c .01), CPM and MMD scores (r = .199, p \u3c .05) and MMD and PATC scores (r = .591, p \u3c .01). Therefore all preconditions for mediation analysis were met. Several regression analyses were conducted to determine the mediation effects of positive attitudes toward cyberbullying on the relationship between cyberbullying behaviors, moral disengagement, and sex. Moral disengagement regressed onto cyberbullying behaviors with statistical significance, indicating there was a relationship that could be mediated (R = .246, p \u3c .05) Moral disengagement also regressed significantly onto positive attitudes toward cyberbullying, establishing a link between the two predictors (R = .596, p \u3c .001). A large, positive correlation was found between self-reported cyberbullying behavior in college students and the optimal linear combination of predictors (R = .462, p \u3c .001), such that as self-reported cyberbullying behaviors increased, so did positive attitudes towards cyberbullying and moral disengagement. In the final regression model, moral disengagement was not statistically significant (B = -.041, p = .250), resulting in complete mediation by positive attitudes toward cyberbullying. Implications. While previous research has shown moral disengagement to be a potential factor in reasons for cyberbullying perpetration behaviors, the current study found that moral disengagement required positive attitudes toward cyberbullying in order to evoke higher rates of cyberbullying. As there is relatively little research examining the relationship between cyberbullying behaviors, moral disengagement, and positive attitudes towards cyberbullying, future research would do well to further investigate these links. Concerning educational bullying prevention and awareness programs, program developers are advised to target attitude change and to include information regarding moral disengagement and its potentially harmful effects

    Asteroseismology and Interferometry

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    Asteroseismology provides us with a unique opportunity to improve our understanding of stellar structure and evolution. Recent developments, including the first systematic studies of solar-like pulsators, have boosted the impact of this field of research within Astrophysics and have led to a significant increase in the size of the research community. In the present paper we start by reviewing the basic observational and theoretical properties of classical and solar-like pulsators and present results from some of the most recent and outstanding studies of these stars. We centre our review on those classes of pulsators for which interferometric studies are expected to provide a significant input. We discuss current limitations to asteroseismic studies, including difficulties in mode identification and in the accurate determination of global parameters of pulsating stars, and, after a brief review of those aspects of interferometry that are most relevant in this context, anticipate how interferometric observations may contribute to overcome these limitations. Moreover, we present results of recent pilot studies of pulsating stars involving both asteroseismic and interferometric constraints and look into the future, summarizing ongoing efforts concerning the development of future instruments and satellite missions which are expected to have an impact in this field of research.Comment: Version as published in The Astronomy and Astrophysics Review, Volume 14, Issue 3-4, pp. 217-36

    Determination of glucose exchange rates and permeability of erythrocyte membrane in preeclampsia and subsequent oxidative stress-related protein damage using dynamic-19F-NMR

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    The cause of the pregnancy condition preeclampsia (PE) is thought to be endothelial dysfunction caused by oxidative stress. As abnormal glucose tolerance has also been associated with PE, we use a fluorinated-mimic of this metabolite to establish whether any oxidative damage to lipids and proteins in the erythrocyte membrane has increased cell membrane permeability. Data were acquired using 19F Dynamic-NMR (DNMR) to measure exchange of 3-fluoro-3-deoxyglucose (3-FDG) across the membrane of erythrocytes from 10 pregnant women (5 healthy control women, and 5 from women suffering from PE). Magnetisation transfer was measured using the 1D selective inversion and 2D EXSY pulse sequences, over a range of time delays. Integrated intensities from these experiments were used in matrix diagonalisation to estimate the values of the rate constants of exchange and membrane permeability. No significant differences were observed for the rate of exchange of 3-FDG and membrane permeability between healthy pregnant women and those suffering from PE, leading us to conclude that no oxidative damage had occurred at this carrier-protein site in the membrane

    A study of the Z production cross-section in pp collisions at √s = 7 using tau final states

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    A measurement of the inclusive Z → ττ cross-section in pp collisions at √s =7 is presented based on a dataset of 1.0 fb[superscript −1] collected by the LHCb detector. Candidates for Z → τ τ decays are identified through reconstructed final states with two muons, a muon and an electron, a muon and a hadron, or an electron and a hadron. The production cross-section for Z bosons, with invariant mass between 60 and 120 GeV/c[superscript 2], which decay to τ leptons with transverse momenta greater than 20 GeV/c and pseudorapidities between 2.0 and 4.5, is measured to be σ[subscript pp]→Z→ττ = 71.4 ± 3.5 ± 2.8 ± 2.5 pb; the first uncertainty is statistical, the second is systematic, and the third is due to the uncertainty on the integrated luminosity. The ratio of the cross-sections for Z → τ τ to Z → μμ is determined to be 0.93 ± 0.09, where the uncertainty is the combination of statistical, systematic, and luminosity uncertainties of the two measurements.National Science Foundation (U.S.

    Precision measurement of the B0s-B¯0s oscillation frequency with the decay B0s → D−sπ+

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    A key ingredient to searches for physics beyond the Standard Model in B0s mixing phenomena is the measurement of the B0s– Bs0{{\overline{ {\mathrm {B}}}{}}^0_{\mathrm { s}}} oscillation frequency, which is equivalent to the mass difference Δms of the B0s mass eigenstates. Using the world's largest B0s meson sample accumulated in a dataset, corresponding to an integrated luminosity of 1.0 fb−1, collected by the LHCb experiment at the CERN LHC in 2011, a measurement of Δms is presented. A total of about 34 000 B0s → D−sπ+ signal decays are reconstructed, with an average decay time resolution of 44 fs. The oscillation frequency is measured to be Δms = 17.768 ± 0.023 (stat) ± 0.006 (syst) ps−1, which is the most precise measurement to date

    Search for Dark Matter and Supersymmetry with a Compressed Mass Spectrum in the Vector Boson Fusion Topology in Proton-Proton Collisions at root s=8 TeV

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    Peer reviewe

    Investigation on the competing effects of clay dispersion and matrix plasticisation for polypropylene/clay nanocomposites. Part II: Crystalline structure and thermo-mechanical behaviour

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    In view of the structure–property relationship, the mechanical property enhancement of polypropylene (PP)/clay nanocomposites can also be associated with the alterations of their crystalline structures and behaviour in addition to the general interpretation of intercalation/exfoliation level and uniform dispersion of more rigid clay platelets with higher aspect ratios in the PP matrix. Wide-angle X-ray diffraction (WAXD) was utilised to evaluate the effects of clay content, maleated PP (MAPP) content (MAPP as the compatibiliser) on PP crystalline structures of nanocomposites. Furthermore, the melting and crystallisation behaviour of PP/clay nanocomposites was also investigated by conducting differential scanning calorimetry (DSC). The thermo-mechanical properties were characterised via dynamic mechanical thermal analysis (DMTA). It is observed that enhancement of mechanical properties are mainly affected by the preferred orientation of PP crystals, the growth of α-PP phase and effective nucleating agent role of additional clay while the excessive amount of MAPP becomes detrimental to these crucial aspects, which is also evidently revealed in DMTA measurements

    Matter and singularities

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    We analyze the structure of matter representations arising from codimension two singularities in F-theory, focusing on gauge groups SU(N). We give a detailed local description of the geometry associated with several types of singularities and the associated matter representations. We also construct global F-theory models for 6D and 4D theories containing these matter representations. The codimension two singularities encountered include examples where the apparent Kodaira singularity type does not need to be completely resolved to produce a smooth Calabi-Yau, examples with rank enhancement by more than one, and examples where the 7-brane configuration is singular. We identify novel phase transitions, in some of which the gauge group remains fixed but the singularity type and associated matter content change along a continuous family of theories. Global analysis of 6D theories on P^2 with 7-branes wrapped on curves of small degree reproduces the range of 6D supergravity theories identified through anomaly cancellation and other consistency conditions. Analogous 4D models are constructed through global F-theory compactifications on P^3, and have a similar pattern of SU(N) matter content. This leads to a constraint on the matter content of a limited class of 4D supergravity theories containing SU(N) as a local factor of the gauge group.Comment: 55 pages, 7 figures; v2: references added; v3: minor correctio
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