8,908 research outputs found

    Reduced Fine-Tuning in Supersymmetry with R-parity violation

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    Both electroweak precision measurements and simple supersymmetric extensions of the standard model prefer a mass of the Higgs boson less than the experimental lower limit of 114 GeV. We show that supersymmetric models with R parity violation and baryon number violation have a significant range of parameter space in which the Higgs dominantly decays to six jets. These decays are much more weakly constrained by current LEP analyses and would allow for a Higgs mass near that of the ZZ. In general, lighter scalar quark and other superpartner masses are allowed and the fine-tuning typically required to generate the measured scale of electroweak symmetry breaking is ameliorated. The Higgs would potentially be discovered at hadron colliders via the appearance of new displaced vertices. The lightest neutralino could be discovered by a scan of vertex-less events LEP I data.Comment: 5 pages, 2 figures. Significant detail added to the arguments regarding LEP limits - made more quantitative. Better figures used, plotting more physical quantities. Typos corrected and references updated. Conclusions unchange

    Improved Parameters and New Lensed Features for Q0957+561 from WFPC2 Imaging

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    New HST WFPC2 observations of the lensed double QSO 0957+561 will allow improved constraints on the lens mass distribution and hence will improve the derived value of H0_0. We first present improved optical positions and photometry for the known components of this lens. The optical separation between the A and B quasar images agrees with VLBI data at the 10 mas level, and the optical center of the primary lensing galaxy G1 coincides with the VLBI source G' to within 10 mas. The best previous model for this lens (Grogin and Narayan 1996) is excluded by these data and must be reevaluated. Several new resolved features are found within 10\arcsec of G1, including an apparent fold arc with two bright knots. Several other small galaxies are detected, including two which may be multiple images of each other. We present positions and crude photometry of these objects.Comment: 7 pages including 2 postscript figures, LaTeX, emulateapj style. Also available at http://www.astro.lsa.umich.edu:80/users/philf/www/papers/list.htm

    Teaching LLCs Through a Problem-Based Approach

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    Case studies and case simulations can be used to teach LLCs with an eye toward training business lawyers. These tools can be used in the traditional four-credit Business Associations (BA) course to supplement traditional teaching materials with mini-case studies that accent and apply analysis of primary legal sources. Alternatively, case studies and case simulations can be the centerpiece of a specialized course on LLCs. We discuss both approaches in this short essay

    Deal Deconstructions, Case Studies, And Case Simulations: Toward Practice Readiness With New Pedagogies In Teaching Business And Transactional Law

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    In this short commentary, we explore the use of two interrelated pedagogical methods for teaching transactional and business law. The first method is deal deconstruction, which analyzes the set of final deal documents and outcomes. This method is backward-looking, conducting a post-mortem on business transactions and analyzing the parties’ choices memorialized in the agreement against the legal and financial alternatives. The second method involves case studies and simulations, which are commonly seen in business schools. This method is forward-looking, exposing students to the uncertainties and situational contexts of doing deals and deal-related litigation. Together, these complementary methods help students understand the tradeoffs and dynamics of transactions and deal negotiations. They provide pedagogical alternatives to the traditional Langdellian method, which relies heavily on the study of edited appellate opinions. By presenting problems in different packages and from different temporal perspectives, these methods hone analytical, deal structuring, problem-solving, and decision-making skills

    Suppression of mitochondrial respiration through recruitment of p160 myb binding protein to PGC-1α : modulation by p38 MAPK

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    The transcriptional coactivator PPAR gamma coactivator 1 α (PGC-1α) is a key regulator of metabolic processes such as mitochondrial biogenesis and respiration in muscle and gluconeogenesis in liver. Reduced levels of PGC-1α in humans have been associated with type II diabetes. PGC-1α contains a negative regulatory domain that attenuates its transcriptional activity. This negative regulation is removed by phosphorylation of PGC-1α by p38 MAPK, an important kinase downstream of cytokine signaling in muscle and β-adrenergic signaling in brown fat. We describe here the identification of p160 myb binding protein (p160MBP) as a repressor of PGC-1α. The binding and repression of PGC-1α by p160MBP is disrupted by p38 MAPK phosphorylation of PGC-1α. Adenoviral expression of p160MBP in myoblasts strongly reduces PGC-1α's ability to stimulate mitochondrial respiration and the expression of the genes of the electron transport system. This repression does not require removal of PGC-1α from chromatin, suggesting that p160MBP is or recruits a direct transcriptional suppressor. Overall, these data indicate that p160MBP is a powerful negative regulator of PGC-1α function and provide a molecular mechanism for the activation of PGC-1α by p38 MAPK. The discovery of p160MBP as a PGC-1α regulator has important implications for the understanding of energy balance and diabetes

    Dark Matter Scaling Relations

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    We establish the presence of a dark matter core radius, for the first time in a very large number of spiral galaxies of all luminosities. Contrary to common opinion we find that the sizes of these cores and the " DM core problem" are bigger for more massive spirals. As a result the Burkert profile provides an excellent mass model for dark halos around disk galaxies. Moreover, we find that the spiral dark matter core densities ρ0\rho_{0} and core radii r0r_{0} lie in the same scaling relation ρ0=4.5×102(r0/kpc)2/3Mpc3\rho_{0}=4.5\times 10^-2 (r_{0}/kpc)^{-2/3} M_{\odot}pc^{-3} of dwarf galaxies with core radii upto ten times more smaller.Comment: 4 pages, 4 figures, Accepted for Publication in Apj Let

    Alignments of the Dominant Galaxies in Poor Clusters

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    We have examined the orientations of brightest cluster galaxies (BCGs) in poor MKW and AWM clusters and find that, like their counterparts in richer Abell clusters, poor cluster BCGs exhibit a strong propensity to be aligned with the principal axes of their host clusters as well as the surrounding distribution of nearby (< 20/h Mpc) Abell clusters. The processes responsible for dominant galaxy alignments are therefore independent of cluster richness. We argue that these alignments most likely arise from anisotropic infall of material into clusters along large-scale filaments.Comment: 8 pages, 5 figure

    The dynamics of Abell 2634

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    We have amassed a large sample of velocity data for the cluster of galaxies Abell 2634 which contains the wide-angle tail (WAT) radio source 3C 465. Robust indicators of location and scale and their confidence intervals are used to determine if the cD galaxy, containing the WAT, has a significant peculiar motion. We find a cD peculiar radial velocity of 219 plus or minus 98 km s(exp -1). Further dynamical analyses, including substructure and normality tests, suggest that A 2634 is an unrelaxed cluster whose radio source structure may be bent by the turbulent gas of a recent cluster-subcluster merger

    The Ellipticity and Orientation of Clusters of Galaxies from N-Body Experiments

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    In this study we use simulations of 1283^3 particles to study the ellipticity and orientation of clusters of galaxies in N-body simulations of differing power-law initial spectra (P(k) \propto k^n ,n = +1, 0, -1, -2),anddensityparameters(), and density parameters (\Omega_0 = 0.2to1.0).Furthermore,unlikemosttheoreticalstudieswemimicmostobserversbyremovingallparticleswhichlieatdistancesgreaterthan21/hMpcfromtheclustercenterofmass.Wecomputedtheaxialratioandtheprincipalaxesusingtheinertiatensorofeachcluster.Themeanellipticityofclustersincreasesstronglywithincreasing to 1.0). Furthermore, unlike most theoretical studies we mimic most observers by removing all particles which lie at distances greater than 2 1/h Mpc from the cluster center of mass. We computed the axial ratio and the principal axes using the inertia tensor of each cluster. The mean ellipticity of clusters increases strongly with increasing n.Wealsofindthatclusterstendtobecomemoresphericalatsmallerradii.Wecomparedtheorientationofaclustertotheorientationofneighboringclustersasafunctionofdistance(correlation).Inaddition,weconsideredwhetheraclustersmajoraxistendstoliealongthelineconnectingittoaneighboringcluster,asafunctionofdistance(alignment).Bothalignmentsandcorrelationswerecomputedinthreedimensionsandinprojectiontomimicobservationalsurveys.Ourresultsshowthatsignificantalignmentsexistforallspectraatsmallseparations(. We also find that clusters tend to become more spherical at smaller radii. We compared the orientation of a cluster to the orientation of neighboring clusters as a function of distance (correlation). In addition, we considered whether a cluster's major axis tends to lie along the line connecting it to a neighboring cluster, as a function of distance (alignment). Both alignments and correlations were computed in three dimensions and in projection to mimic observational surveys. Our results show that significant alignments exist for all spectra at small separations (D < 15 h^{-1}Mpc)butdropsoffatlargerdistanceinastrongly Mpc) but drops off at larger distance in a strongly n-$dependent way.Comment: 22 pages, requires aaspp4.sty, flushrt.sty, and epsf.sty Revised manuscript, accepted for publication in Ap
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