1,629 research outputs found

    Foreword

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    Miller v. Alabama: Something Unconsitutional Now Was Equally Unconstitutional Then

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    In June 2012, the United States Supreme Court found mandatory life-without-parole sentences against juvenile offenders unconstitutional in Miller v. Alabama. The Court determined that because children possess “immaturity, impetuosity, and [fail] to appreciate risks and consequences,” they are fundamentally different than adults. Although Miller invalidated every juvenile mandatory life-without-parole (JMLWOP) statute across the United States, there is no clear indication regarding whether Miller retroactively applies to juveniles sentenced to mandatory life-without-parole before the Court’s ruling. As a result, states are split on whether to apply Miller retroactively. Fifteen states have yet to decide whether Miller applies retroactively, while several other states have either (1) declined to give Miller a retroactive effect or (2) passed legislation that does not apply Miller retroactively or provide for resentencing for JMLWOP. This Comment evaluates why the States should apply Miller retroactively

    "Big" Divisor D3/D7 Swiss Cheese Phenomenology

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    We review progress made over the past couple of years in the field of Swiss Cheese Phenomenology involving a mobile space-time filling D3-brane and stack(s) of fluxed D7-branes wrapping the "big" (as opposed to the "small") divisor in (the orientifold of a) Swiss-Cheese Calabi-Yau. The topics reviewed include reconciliation of large volume cosmology and phenomenology, evaluation of soft supersymmetry breaking parameters, one-loop RG-flow equations' solutions for scalar masses, obtaining fermionic (possibly first two generations' quarks/leptons) mass scales in the O(MeV-GeV)-regime as well as (first two generations') neutrino masses (and their one-loop RG flow) of around an eV. The heavy sparticles and the light fermions indicate the possibility of "split SUSY" large volume scenario.Comment: Invited review for MPLA, 14 pages, LaTe

    Young stars at large distances from the galactic plane: mechanisms of formation

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    We have collected from the literature a list of early-type stars, situated at large distances from the galactic plane, for which evidence of youth seems convincing. We discuss two possible formation mechanisms for these stars: ejection from the plane by dynamical interactions within small clusters, and formation away from the plane, via induced shocks created by spiral density waves. We identify the stars that could be explained by each mechanism. We conclude that the ejection mechanism can account for about two thirds of the stars, while a combination of star formation at z = 500-800 pc from the plane and ejection, can account for 90 percent of these stars. Neither mechanism, nor both together, can explain the most extreme examples.Comment: 6 pages, No figures. Sixth Pacific Rim Conference on Stellar Astrophysics - A tribute to Helmut Abt, (Kluwer

    LARGE Volume String Compactifications at Finite Temperature

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    We present a detailed study of the finite-temperature behaviour of the LARGE Volume type IIB flux compactifications. We show that certain moduli can thermalise at high temperatures. Despite that, their contribution to the finite-temperature effective potential is always negligible and the latter has a runaway behaviour. We compute the maximal temperature TmaxT_{max}, above which the internal space decompactifies, as well as the temperature TT_*, that is reached after the decay of the heaviest moduli. The natural constraint T<TmaxT_*<T_{max} implies a lower bound on the allowed values of the internal volume V\mathcal{V}. We find that this restriction rules out a significant range of values corresponding to smaller volumes of the order V104ls6\mathcal{V}\sim 10^{4}l_s^6, which lead to standard GUT theories. Instead, the bound favours values of the order V1015ls6\mathcal{V}\sim 10^{15}l_s^6, which lead to TeV scale SUSY desirable for solving the hierarchy problem. Moreover, our result favours low-energy inflationary scenarios with density perturbations generated by a field, which is not the inflaton. In such a scenario, one could achieve both inflation and TeV-scale SUSY, although gravity waves would not be observable. Finally, we pose a two-fold challenge for the solution of the cosmological moduli problem. First, we show that the heavy moduli decay before they can begin to dominate the energy density of the Universe. Hence they are not able to dilute any unwanted relics. And second, we argue that, in order to obtain thermal inflation in the closed string moduli sector, one needs to go beyond the present EFT description.Comment: 54 pages + appendix, 5 figures; v2: minor corrections, references and footnotes added, version published on JCA

    Natural Quintessence in String Theory

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    We introduce a natural model of quintessence in string theory where the light rolling scalar is radiatively stable and couples to Standard Model matter with weaker-than- Planckian strength. The model is embedded in an anisotropic type IIB compactification with two exponentially large extra dimensions and TeV-scale gravity. The bulk turns out to be nearly supersymmetric since the scale of the gravitino mass is of the order of the observed value of the cosmological constant. The quintessence field is a modulus parameterising the size of an internal four-cycle which naturally develops a potential of the order (gravitino mass)^4, leading to a small dark energy scale without tunings. The mass of the quintessence field is also radiatively stable since it is protected by supersymmetry in the bulk. Moreover, this light scalar couples to ordinary matter via its mixing with the volume mode. Due to the fact that the quintessence field is a flat direction at leading order, this mixing is very small, resulting in a suppressed coupling to Standard Model particles which avoids stringent fifth-force constraints. On the other hand, if dark matter is realised in terms of Kaluza-Klein states, unsuppressed couplings between dark energy and dark matter can emerge, leading to a scenario of coupled quintessence within string theory. We study the dynamics of quintessence in our set-up, showing that its main features make it compatible with observations.Comment: 26 page

    Preliminary analysis of space mission applications for electromagnetic launchers

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    The technical and economic feasibility of using electromagnetically launched EML payloads propelled from the Earth's surface to LEO, GEO, lunar orbit, or to interplanetary space was assessed. Analyses of the designs of rail accelerators and coaxial magnetic accelerators show that each is capable of launching to space payloads of 800 KG or more. A hybrid launcher in which EML is used for the first 2 KM/sec followed by chemical rocket stages was also tested. A cost estimates study shows that one to two EML launches per day are needed to break even, compared to a four-stage rocket. Development models are discussed for: (1) Earth orbital missions; (2) lunar base supply mission; (3) solar system escape mission; (4) Earth escape missions; (5) suborbital missions; (6) electromagnetic boost missions; and (7) space-based missions. Safety factors, environmental impacts, and EML systems analysis are discussed. Alternate systems examined include electrothermal thrustors, an EML rocket gun; an EML theta gun, and Soviet electromagnetic accelerators

    Academic Primer Series: Five Key Papers for Consulting Clinician Educators.

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    INTRODUCTION: Clinician educators are often asked to perform consultations for colleagues. Invitations to consult and advise others on local problems can help foster great collaborations between centers, and allows for an exchange of ideas between programs. In this article, the authors identify and summarize several key papers to assist emerging clinician educators with the consultation process. METHODS: A consensus-building process was used to generate a list of key papers that describe the importance and significance of educational consulting, informed by social media sources. A three-round voting methodology, akin to a Delphi study, determined the most impactful papers from the larger list. RESULTS: Summaries of the five most highly rated papers on education consultation are presented in this paper. These papers were determined by a mixed group of junior and senior faculty members, who have summarized these papers with respect to their relevance for their peer groups. CONCLUSION: Five key papers on the educational consultation process are presented in this paper. These papers offer background and perspective to help junior faculty gain a grasp of consultation processes

    Foreword

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    Bootstrapping the Coronal Magnetic Field with STEREO: I. Unipolar Potential Field Modeling

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    We investigate the recently quantified misalignment of αmis2040\alpha_{mis} \approx 20^\circ-40^\circ between the 3-D geometry of stereoscopically triangulated coronal loops observed with STEREO/EUVI (in four active regions) and theoretical (potential or nonlinear force-free) magnetic field models extrapolated from photospheric magnetograms. We develop an efficient method of bootstrapping the coronal magnetic field by forward-fitting a parameterized potential field model to the STEREO-observed loops. The potential field model consists of a number of unipolar magnetic charges that are parameterized by decomposing a photospheric magnetogram from MDI. The forward-fitting method yields a best-fit magnetic field model with a reduced misalignment of αPF1320\alpha_{PF} \approx 13^\circ-20^\circ. We evaluate also stereoscopic measurement errors and find a contribution of αSE712\alpha_{SE}\approx 7^\circ-12^\circ, which constrains the residual misalignment to αNP=αPFαSE59\alpha_{NP}=\alpha_{PF}-\alpha_{SE}\approx 5^\circ -9^\circ, which is likely due to the nonpotentiality of the active regions. The residual misalignment angle αNP\alpha_{NP} of the potential field due to nonpotentiality is found to correlate with the soft X-ray flux of the active region, which implies a relationship between electric currents and plasma heating.Comment: 12 figures, manuscript submitted to ApJ, 2010 Apr 2
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