Charged anisotropic matter with linear equation of state

We consider the general situation of a compact relativistic body with anisotropic pressures in the presence of the electromagnetic field. The equation of state for the matter distribution is linear and may be applied to strange stars with quark matter. Three classes of new exact solutions are found to the Einstein-Maxwell system. This is achieved by specifying a particular form for one of the gravitational potentials and the electric field intensity. We can regain anisotropic and isotropic models from our general class of solution. A physical analysis indicates that the charged solutions describe realistic compact spheres with anisotropic matter distribution. The equation of state is consistent with dark energy stars and charged quark matter distributions. The masses and central densities correspond to realistic stellar objects in the general case when anisotropy and charge are present.Comment: 17 pages, To appear in Class. Quantum Gra

Screening of Hydrodynamic Interactions in Semidilute Polymer Solutions: A Computer Simulation Study

We study single-chain motion in semidilute solutions of polymers of length N = 1000 with excluded-volume and hydrodynamic interactions by a novel algorithm. The crossover length of the transition from Zimm (short lengths and times) to Rouse dynamics (larger scales) is proportional to the static screening length. The crossover time is the corresponding Zimm time. Our data indicate Zimm behavior at large lengths but short times. There is no hydrodynamic screening until the chains feel constraints, after which they resist the flow: "Incomplete screening" occurs in the time domain.Comment: 3 figure

Successful Transplantation of a Split Crossed Fused Ectopic Kidney into a Patient with End-Stage Renal Disease

Potential donors with congenital renal anomalies but normal renal function are often overlooked because of a possible increase in technical difficulty and complications associated with the surgery. However, as the waiting list for a deceased donor kidney transplant continues to grow, it is important to consider these kidneys for potential transplant. This paper describes the procurement of a crossed fused ectopic kidney, and subsequent parenchymal transection prior to transplantation as part of a combined simultaneous kidney pancreas transplant. The transplant was uncomplicated, and the graft had immediate function. The patient is now two years from transplant with excellent function

Linear Response, Validity of Semi-Classical Gravity, and the Stability of Flat Space

A quantitative test for the validity of the semi-classical approximation in gravity is given. The criterion proposed is that solutions to the semi-classical Einstein equations should be stable to linearized perturbations, in the sense that no gauge invariant perturbation should become unbounded in time. A self-consistent linear response analysis of these perturbations, based upon an invariant effective action principle, necessarily involves metric fluctuations about the mean semi-classical geometry, and brings in the two-point correlation function of the quantum energy-momentum tensor in a natural way. This linear response equation contains no state dependent divergences and requires no new renormalization counterterms beyond those required in the leading order semi-classical approximation. The general linear response criterion is applied to the specific example of a scalar field with arbitrary mass and curvature coupling in the vacuum state of Minkowski spacetime. The spectral representation of the vacuum polarization function is computed in n dimensional Minkowski spacetime, and used to show that the flat space solution to the semi-classical Einstein equations for n=4 is stable to all perturbations on distance scales much larger than the Planck length.Comment: 22 pages: This is a significantly expanded version of gr-qc/0204083, with two additional sections and two new appendices giving a complete, explicit example of the semi-classical stability criterion proposed in the previous pape

A procedure for identifying possible products in the Assembly-Disassembly-Organisation-Reassembly (ADOR) synthesis of zeolites

The authors would like to thank the EPSRC (grants: EP/K025112/1; EP/K005499/1; EP/K503162/1; EP/N509759/1) for funding opportunities. R.E.M., J.C. and M.M. would like to acknowledge OP VVV "Excellent Research Teams", project No. CZ.02.1.01/0.0/0.0/15_003/0000417 - CUCAM. S.E.A. would like to thank the Royal Society and the Wolfson Foundation for a merit award. J.C. acknowledges the Czech Science Foundation (P106/12/G015).High-silica zeolites, some of the most important and widely used catalysts in industry, have potential for application across a wide range of traditional and emerging technologies. The many structural topologies of zeolites have a variety of potential uses, so a strong drive to create new zeolites exists. Here, we present a protocol, the assembly–disassembly–organization–reassembly (ADOR) process, for a relatively new method of preparing these important solids. It allows the synthesis of new high-silica zeolites (Si/Al >1,000), whose synthesis is considered infeasible with traditional (solvothermal) methods, offering new topologies that may find novel applications. We show how to identify the optimal conditions (e.g., duration of reaction, temperature, acidity) for ADOR, which is a complex process with different possible outcomes. Following the protocol will allow researchers to identify the different products that are possible from a reaction without recourse to repetitive and time-consuming trial and error. In developing the protocol, germanium-containing UTL zeolites were subjected to hydrolysis conditions using both water and hydrochloric acid as media, which provides an understanding of the effects of temperature and pH on the disassembly (D) and organization (O) steps of the process that define the potential products. Samples were taken from the ongoing reaction periodically over a minimum of 8 h, and each sample was analyzed using powder X-ray diffraction to yield a time course for the reaction at each set of conditions; selected samples were analyzed using transmission electron microscopy and solid-state NMR spectroscopy.PostprintPeer reviewe

Attractor states and infrared scaling in de Sitter space

The renormalized expectation value of the energy-momentum tensor for a scalar field with any mass m and curvature coupling xi is studied for an arbitrary homogeneous and isotropic physical initial state in de Sitter spacetime. We prove quite generally that has a fixed point attractor behavior at late times, which depends only on m and xi, for any fourth order adiabatic state that is infrared finite. Specifically, when m^2 + xi R > 0, approaches the Bunch-Davies de Sitter invariant value at late times, independently of the initial state. When m = xi = 0, it approaches instead the de Sitter invariant Allen-Folacci value. When m = 0 and xi \ge 0 we show that this state independent asymptotic value of the energy-momentum tensor is proportional to the conserved geometrical tensor (3)H_{ab}, which is related to the behavior of the quantum effective action of the scalar field under global Weyl rescaling. This relationship serves to generalize the definition of the trace anomaly in the infrared for massless, non-conformal fields. In the case m^2 + xi R = 0, but m and xi separately different from zero, grows linearly with cosmic time at late times. For most values of m and xi in the tachyonic cases, m^2 + xi R grows exponentially at late cosmic times for all physically admissable initial states.Comment: 30 pages, 6 figures, 46 kB tar.gz fil

Molecular velocity auto-correlation of simple liquids observed by NMR MGSE method

The velocity auto-correlation spectra of simple liquids obtained by the NMR method of modulated gradient spin echo show features in the low frequency range up to a few kHz, which can be explained reasonably well by a $t^{-3/2}$ long time tail decay only for non-polar liquid toluene, while the spectra of polar liquids, such as ethanol, water and glycerol, are more congruent with the model of diffusion of particles temporarily trapped in potential wells created by their neighbors. As the method provides the spectrum averaged over ensemble of particle trajectories, the initial non-exponential decay of spin echoes is attributed to a spatial heterogeneity of molecular motion in a bulk of liquid, reflected in distribution of the echo decays for short trajectories. While at longer time intervals, and thus with longer trajectories, heterogeneity is averaged out, giving rise to a spectrum which is explained as a combination of molecular self-diffusion and eddy diffusion within the vortexes of hydrodynamic fluctuations.Comment: 8 pages, 6 figur

A systematic review of the use of financial incentives and penalties to encourage uptake of healthy behaviors: protocol

<p>Abstract</p> <p>Background</p> <p>The use of financial incentives and penalties to encourage uptake of healthy behaviors is increasingly seen as a viable intervention in developed countries. Previous reviews of the effectiveness of financial incentives and penalties for encouraging the uptake of healthy behaviors have focused on individual behaviors making it difficult to draw overall conclusions about the effectiveness of such interventions. This systematic review will explore the effectiveness of financial incentives and penalties for encouraging a wide range of behaviors, including: smoking cessation, increased physical activity, healthier dietary intake, sensible patterns of alcohol consumption, safe sun, safe sex, and primary preventive clinical behaviors.</p> <p>Methods</p> <p>Systematic methods will be used to search existing literature and screen studies for inclusion. All studies that meet the following inclusion criteria will be included in the review: participants were 18 years old or older and living in high-income countries; interventions included cash or cash-like incentives to promote the uptake of healthy behaviors, or cash or cash-like penalties to discourage unhealthy behaviors; the comparator was usual care or no intervention; study design was randomized controlled trial, cluster randomized controlled trial, controlled before and after study, or interrupted time series analysis. Two reviewers will independently screen the publications to ensure they meet the inclusion criteria. Quality will be assessed by two researchers, working independently, using the Cochrane risk of bias tool. Meta-analysis will be conducted, if appropriate. Any studies identified as at ‘high risk of bias’ will be excluded from meta-analysis.</p> <p>Discussion</p> <p>This systematic review will provide policy-relevant recommendations for the use of financial incentives and penalties as a method of encouraging uptake of healthy behaviors.</p

Testosterone and Cortisol Release among Spanish Soccer Fans Watching the 2010 World Cup Final

This field study investigated the release of testosterone and cortisol of a vicarious winning experience in Spanish fans watching the finals between Spain and the Netherlands in the 2010 FIFA World Cup Soccer. Spanish fans (n = 50) watched the match with friends or family in a public place or at home and also participated in a control condition. Consistent with hypotheses, results revealed that testosterone and cortisol levels were higher when watching the match than on a control day. However, neither testosterone nor cortisol levels increased after the victory of the Spanish team. Moreover, the increase in testosterone secretion was not related to participants' sex, age or soccer fandom, but the increase in total cortisol secretion during the match was higher among men than among women and among fans that were younger. Also, increases in cortisol secretion were greater to the degree that people were a stronger fan of soccer. Level of fandom further appeared to account for the sex effect, but not for the age effect. Generally, the testosterone data from this study are in line with the challenge hypothesis, as testosterone levels of watchers increased to prepare their organism to defend or enhance their social status. The cortisol data from this study are in line with social self-preservation theory, as higher cortisol secretion among young and greater soccer fans suggests that especially they perceived that a negative outcome of the match would threaten their own social esteem