Gauss-Bonnet gravity, brane world models, and non-minimal coupling

We study the case of brane world models with an additional Gauss-Bonnet term in the presence of a bulk scalar field which interacts non-minimally with gravity, via a possible interaction term of the form $-1/2 \xi R \phi^2$. The Einstein equations and the junction conditions on the brane are formulated, in the case of the bulk scalar field. Static solutions of this model are obtained by solving numerically the Einstein equations with the appropriate boundary conditions on the brane. Finally, we present graphically and comment these solutions for several values of the free parameters of the model.Comment: 13 pages,4 figures, published versio

Graviton localization and Newton's law for brane models with a non-minimally coupled bulk scalar field

Brane world models with a non-minimally coupled bulk scalar field have been studied recently. In this paper we consider metric fluctuations around an arbitrary gravity-scalar background solution, and we show that the corresponding spectrum includes a localized zero mode which strongly depends on the profile of the background scalar field. For a special class of solutions, with a warp factor of the RS form, we solve the linearized Einstein equations, for a point-like mass source on the brane, by using the brane bending formalism. We see that general relativity on the brane is recovered only if we impose restrictions on the parameter space of the models under consideration.Comment: 17 pages, revised versio

Mapping EK Draconis with PEPSI - Possible evidence for starspot penumbrae

We present the first temperature surface map of EK Dra from very-high-resolution spectra obtained with the Potsdam Echelle Polarimetric and Spectroscopic Instrument (PEPSI) at the Large Binocular Telescope. Changes in spectral line profiles are inverted to a stellar surface temperature map using our $i$Map code. The long-term photometric record is employed to compare our map with previously published maps. Four cool spots were reconstructed, but no polar spot was seen. The temperature difference to the photosphere of the spots is between 990 and 280K. Two spots are reconstructed with a typical solar morphology with an umbra and a penumbra. For the one isolated and relatively round spot (A), we determine an umbral temperature of 990K and a penumbral temperature of 180K below photospheric temperature. The umbra to photosphere intensity ratio of EK Dra is approximately only half of that of a comparison sunspot. A test inversion from degraded line profiles showed that the higher spectral resolution of PEPSI reconstructs the surface with a temperature difference that is on average 10% higher than before and with smaller surface areas by 10-20%. PEPSI is therefore better suited to detecting and characterising temperature inhomogeneities. With ten more years of photometry, we also refine the spot cycle period of EK Dra to 8.9$\pm$0.2 years with a continuing long-term fading trend. The temperature morphology of spot A so far appears to show the best evidence for the existence of a solar-like penumbra for a starspot. We emphasise that it is more the non-capture of the true umbral contrast rather than the detection of the weak penumbra that is the limiting factor. The relatively small line broadening of EK Dra, together with the only moderately high spectral resolutions previously available, appear to be the main contributors to the lower-than-expected spot contrasts when comparing to the Sun.Comment: Accepted for A&

Rest Interval Length Does Not Affect Total Exercise Volume During Lower Body Resistance Training

Please refer to the pdf version of the abstract located adjacent to the title

Holographic fermions in external magnetic fields

We study the Fermi level structure of 2+1-dimensional strongly interacting electron systems in external magnetic field using the AdS/CFT correspondence. The gravity dual of a finite density fermion system is a Dirac field in the background of the dyonic AdS-Reissner-Nordstrom black hole. In the probe limit the magnetic system can be reduced to the non-magnetic one, with Landau-quantized momenta and rescaled thermodynamical variables. We find that at strong enough magnetic fields, the Fermi surface vanishes and the quasiparticle is lost either through a crossover to conformal regime or through a phase transition to an unstable Fermi surface. In the latter case, the vanishing Fermi velocity at the critical magnetic field triggers the non-Fermi liquid regime with unstable quasiparticles and a change in transport properties of the system. We associate it with a metal-"strange metal" phase transition. Next we compute the DC Hall and longitudinal conductivities using the gravity-dressed fermion propagators. For dual fermions with a large charge, many different Fermi surfaces contribute and the Hall conductivity is quantized as expected for integer Quantum Hall Effect (QHE). At strong magnetic fields, as additional Fermi surfaces open up, new plateaus typical for the fractional QHE appear. The somewhat irregular pattern in the length of fractional QHE plateaus resemble the outcomes of experiments on thin graphite in a strong magnetic field. Finally, motivated by the absence of the sign problem in holography, we suggest a lattice approach to the AdS calculations of finite density systems.Comment: 34 pages, 14 figure

Conflict of Laws (2009)

States\u27 and nations\u27 laws collide when foreign factors appear in a lawsuit. Nonresident litigants, incidents outside the forum, parallel lawsuits, and judgments from other jurisdictions can create problems with personal jurisdiction, choice of law, and the recognition of foreign judgments. This article reviews Texas conflicts cases from Texas state and federal courts during the Survey period from October 1, 2007, through September 30, 2008. The article excludes cases involving federal-state conflicts, intrastate issues such as subject matter jurisdiction and venue, and conflicts in time, such as the applicability of prior or subsequent law within a state. State and federal cases are discussed together because conflict of laws is mostly a state law topic, except for a few constitutional limits, resulting in the same rules applying to most issues in state and federal courts. Although no data are readily available to confirm this, Texas is no doubt a primary state in the production of conflict-of-laws precedents. This results not only from its size and population, but also from its placement, bordering four states, a civil-law nation, and international shipping. Only California shares these factors, with the partial exception of the states bordering Quebec. Furthermore, Texas courts experience every range of conflict-of-laws litigation. In addition to a large number of opinions on garden variety examples of personal jurisdiction, Texas courts produce case law every year on internet-based jurisdiction, prorogating and derogating forum selection clauses, federal long-arm statutes with nationwide process, international forum non conveniens, parallel litigation, international family law issues, and private lawsuits against foreign sovereigns. Interstate and international judgment recognition and enforcement offer fewer annual examples, possibly a sign of that subject\u27s administrative nature that results in only a few reported cases. Texas state and federal courts provide a fascinating study of conflicts issues every year, but the volume of case law now greatly exceeds this Survey\u27s ability to report on them, a function both of journal space and authors\u27 time. Accordingly, this Survey period\u27s article focuses on selective cases

Conflict of Laws (2009)

States\u27 and nations\u27 laws collide when foreign factors appear in a lawsuit. Nonresident litigants, incidents outside the forum, parallel lawsuits, and judgments from other jurisdictions can create problems with personal jurisdiction, choice of law, and the recognition of foreign judgments. This article reviews Texas conflicts cases from Texas state and federal courts during the Survey period from October 1, 2007, through September 30, 2008. The article excludes cases involving federal-state conflicts, intrastate issues such as subject matter jurisdiction and venue, and conflicts in time, such as the applicability of prior or subsequent law within a state. State and federal cases are discussed together because conflict of laws is mostly a state law topic, except for a few constitutional limits, resulting in the same rules applying to most issues in state and federal courts. Although no data are readily available to confirm this, Texas is no doubt a primary state in the production of conflict-of-laws precedents. This results not only from its size and population, but also from its placement, bordering four states, a civil-law nation, and international shipping. Only California shares these factors, with the partial exception of the states bordering Quebec. Furthermore, Texas courts experience every range of conflict-of-laws litigation. In addition to a large number of opinions on garden variety examples of personal jurisdiction, Texas courts produce case law every year on internet-based jurisdiction, prorogating and derogating forum selection clauses, federal long-arm statutes with nationwide process, international forum non conveniens, parallel litigation, international family law issues, and private lawsuits against foreign sovereigns. Interstate and international judgment recognition and enforcement offer fewer annual examples, possibly a sign of that subject\u27s administrative nature that results in only a few reported cases. Texas state and federal courts provide a fascinating study of conflicts issues every year, but the volume of case law now greatly exceeds this Survey\u27s ability to report on them, a function both of journal space and authors\u27 time. Accordingly, this Survey period\u27s article focuses on selective cases