579 research outputs found

    Symmetry Nonrestoration in a Gross-Neveu Model with Random Chemical Potential

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    We study the symmetry behavior of the Gross-Neveu model in three and two dimensions with random chemical potential. This is equivalent to a four-fermion model with charge conjugation symmetry as well as Z_2 chiral symmetry. At high temperature the Z_2 chiral symmetry is always restored. In three dimensions the initially broken charge conjugation symmetry is not restored at high temperature, irrespective of the value of the disorder strength. In two dimensions and at zero temperature the charge conjugation symmetry undergoes a quantum phase transition from a symmetric state (for weak disorder) to a broken state (for strong disorder) as the disorder strength is varied. For any given value of disorder strength, the high-temperature behavior of the charge conjugation symmetry is the same as its zero-temperature behavior. Therefore, in two dimensions and for strong disorder strength the charge conjugation symmetry is not restored at high temperature.Comment: 16 pages, 3 figure

    Current constraints on Cosmological Parameters from Microwave Background Anisotropies

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    We compare the latest observations of Cosmic Microwave Background (CMB) Anisotropies with the theoretical predictions of the standard scenario of structure formation. Assuming a primordial power spectrum of adiabatic perturbations we found that the total energy density is constrained to be Ωtot=1.03±0.06\Omega_{tot}=1.03\pm0.06 while the energy density in baryon and Cold Dark Matter (CDM) are Ωbh2=0.021±0.003\Omega_bh^2=0.021\pm0.003 and Ωcdmh2=0.12±0.02\Omega_{cdm}h^2=0.12\pm0.02, (all at 68% C.L.) respectively. The primordial spectrum is consistent with scale invariance, (ns=0.97±0.04n_s=0.97\pm0.04) and the age of the universe is t0=14.6±0.9t_0=14.6\pm0.9 Gyrs. Adding informations from Large Scale Structure and Supernovae, we found a strong evidence for a cosmological constant ΩΛ=0.70−0.05+0.07\Omega_{\Lambda}=0.70_{-0.05}^{+0.07} and a value of the Hubble parameter h=0.69±0.07h=0.69\pm0.07. Restricting this combined analysis to flat universes, we put constraints on possible 'extensions' of the standard scenario. A gravity waves contribution to the quadrupole anisotropy is limited to be r≀0.42r \le 0.42 (95% c.l.). A constant equation of state for the dark energy component is bound to be wQ≀−0.74w_Q \le -0.74 (95% c.l.). We constrain the effective relativistic degrees of freedom NΜ≀6.2N_\nu \leq 6.2 and the neutrino chemical potential −0.01≀Οe≀0.18-0.01 \leq \xi_e \leq 0.18 and âˆŁÎŸÎŒ,Ï„âˆŁâ‰€2.3|\xi_{\mu,\tau}|\leq 2.3 (massless neutrinos).Comment: The status of cosmological parameters before WMAP. In press on Phys. Rev. D., Rapid Communication, 6 pages, 5 figure

    Implementation of a pharmacogenomics consult service to support the INGENIOUS trial

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    Hospital systems increasingly utilize pharmacogenomic testing to inform clinical prescribing. Successful implementation efforts have been modeled at many academic centers. In contrast, this report provides insights into the formation of a pharmacogenomics consultation service at a safety-net hospital, which predominantly serves low-income, uninsured, and vulnerable populations. The report describes the INdiana GENomics Implementation: an Opportunity for the UnderServed (INGENIOUS) trial and addresses concerns of adjudication, credentialing, and funding

    Probing R-parity violating models of neutrino mass at the Tevatron via top Squark decays

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    We have estimated the limiting branching ratio of the R-parity violating (RPV) decay of the lighter top squark, \tilde t_1 \ar l^+ d (l=el=e or ÎŒ\mu and d is a down type quark of any flavor), as a function of top squark mass(\MST) for an observable signal in the di-lepton plus di-jet channel at the Tevatron RUN-II experiment with 2 fb−1^{-1} luminosity. Our simulations indicate that the lepton number violating nature of the underlying decay dynamics can be confirmed via the reconstruction of \MST. The above decay is interesting in the context of RPV models of neutrino mass where the RPV couplings (λi3jâ€Č\lambda'_{i3j}) driving the above decay are constrained to be small (\lsim 10^{-3} - 10^{-4} ). If t~1\tilde t_1 is the next lightest super particle - a theoretically well motivated scenario - then the RPV decay can naturally compete with the R-parity conserving (RPC) modes which also have suppressed widths. The model independent limiting BR can delineate the parameter space in specific supersymmetric models, where the dominating RPV decay is observable and predict the minimum magnitude of the RPV coupling that will be sensitive to Run-II data. We have found it to be in the same ballpark value required by models of neutrino mass, for a wide range of \MST. A comprehensive future strategy for linking top squark decays with models of neutrino mass is sketched.Comment: 28 pages, 14 Figure

    Review of magnetic gear technologies and their applications in marine energy

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    The marine energy industry is in its early stages but has a large potential for growth. One of the most significant challenges is the reduction of operation and maintenance costs. Magnetic gears (MGs) offer the potential for long periods between maintenance intervals due to their frictionless torque transmission which could reduce these costs. This study presents a summary of the state of the art in MG technology and then investigates its potential for marine energy applications. A brief overview is given of the state of the marine energy industry and the environment in which marine energy converters (MECs) operate. A short history of MG development over the past century is then presented followed by a discussion of the leading MG technologies and their relative advantages. In order to demonstrate the potential of MGs in marine applications, the current technologies, i.e. mechanically geared and direct drive machines, are examined in terms of sizing, reliability and economic value using previous studies on a similar technology, namely wind. MGs are applied to four types of MECs to demonstrate how the technology can be incorporated. The potential to deploy at scale and potential obstacles to this are then discussed

    The role of self-gentrification in sustainable tourism: Indigenous entrepreneurship at Honghe Hani Rice Terraces World Heritage Site, China

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    This article examines three forms of tourism gentrification occurring within the newly inscribed (2013) Honghe Hani Rice Terraces UNESCO World Heritage Site in Yunnan, China. The indigenous Hani and Yi communities who populate this remote mountainous area, possess distinct cultural practices that have supported the rice terrace ecosystem for centuries. This article draws on interviews and non-participant observation conducted with inhabitants and newcomers to analyse the types of gentrification occurring within the site. We argue that indigenous cultural practices, and consequently rice cultivation in the area, are threatened by gentrifier-led and state-led gentrification combined with high levels of outward migration of indigenous persons. This could pose a significant threat to the sustainability of tourism at this site and may ultimately compromise the site’s World Heritage Status. In the midst of these dangers, some indigenous people are shown to be improving their socioeconomic standing – and becoming “middle class” or “gentry” – particularly through adopting entrepreneurial strategies gleaned from their encounters with outside-gentrifiers and tourists. This article proposes the concept of “self-gentrification” as a way to describe individuals who seek to improve themselves and their own community, while under threat of gentrification
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