Coarse Brownian Dynamics for Nematic Liquid Crystals: Bifurcation Diagrams via Stochastic Simulation

We demonstrate how time-integration of stochastic differential equations (i.e. Brownian dynamics simulations) can be combined with continuum numerical bifurcation analysis techniques to analyze the dynamics of liquid crystalline polymers (LCPs). Sidestepping the necessity of obtaining explicit closures, the approach analyzes the (unavailable in closed form) coarse macroscopic equations, estimating the necessary quantities through appropriately initialized, short bursts of Brownian dynamics simulation. Through this approach, both stable and unstable branches of the equilibrium bifurcation diagram are obtained for the Doi model of LCPs and their coarse stability is estimated. Additional macroscopic computational tasks enabled through this approach, such as coarse projective integration and coarse stabilizing controller design, are also demonstrated

High-Temperature Activated AB2 Nanopowders for Metal Hydride Hydrogen Compression

A reliable process for compressing hydrogen and for removing all contaminants is that of the metal hydride thermal compression. The use of metal hydride technology in hydrogen compression applications though, requires thorough structural characterization of the alloys and investigation of their sorption properties. The samples have been synthesized by induction - levitation melting and characterized by Rietveld analysis of the X-Ray diffraction (XRD) patterns. Volumetric PCI (Pressure-Composition Isotherm) measurements have been conducted at 20, 60 and 90 oC, in order to investigate the maximum pressure that can be reached from the selected alloys using water of 90oC. Experimental evidence shows that the maximum hydrogen uptake is low since all the alloys are consisted of Laves phases, but it is of minor importance if they have fast kinetics, given a constant volumetric hydrogen flow. Hysteresis is almost absent while all the alloys release nearly all the absorbed hydrogen during desorption. Due to hardware restrictions, the maximum hydrogen pressure for the measurements was limited at 100 bars. Practically, the maximum pressure that can be reached from the last alloy is more than 150 bars.Comment: 9 figures. arXiv admin note: text overlap with arXiv:1207.354

Simulations of the Poynting--Robertson Cosmic Battery in Resistive Accretion Disks

We describe the results of numerical "2.5--dimensional" MHD simulations of an initially unmagnetized disk model orbiting a central point--mass and responding to the continual generation of poloidal magnetic field due to a secular source that emulates the Poynting--Robertson (PR) drag on electrons in the vicinity of a luminous stellar or compact accreting object. The fluid in the disk and in the surrounding hotter atmosphere has finite electrical conductivity and allows for the magnetic field to diffuse freely out of the areas where it is generated, while at the same time, the differential rotation of the disk twists the poloidal field and quickly induces a substantial toroidal--field component. The secular PR term has dual purpose in these simulations as the source of the magnetic field and the trigger of a magnetorotational instability (MRI) in the disk. The MRI is especially mild and does not destroy the disk because a small amount of resistivity dampens the instability efficiently. In simulations with moderate resistivities (diffusion timescales up to $\sim$16 local dynamical times) and after $\sim$100 orbits, the MRI has managed to transfer outward substantial amounts of angular momentum and the inner edge of the disk, along with azimuthal magnetic flux, has flowed toward the central point--mass where a new, magnetized, nuclear disk has formed. The toroidal field in this nuclear disk is amplified by differential rotation and it cannot be contained; when it approaches equipartition, it unwinds vertically and produces episodic jet--like outflows. The poloidal field in the inner region cannot diffuse back out if the characteristic diffusion time is of the order of or larger than the dynamical time; it continues to grow linearly in time undisturbed and without saturation, as the outer sections of many poloidal loops are being drawn radially outward.Comment: 27 pages, 55 figure

Einstein--Maxwell--Dilaton metrics from three--dimensional Einstein--Weyl structures

A class of time dependent solutions to $(3+1)$ Einstein--Maxwell-dilaton theory with attractive electric force is found from Einstein--Weyl structures in (2+1) dimensions corresponding to dispersionless Kadomtsev--Petviashvili and $SU(\infty)$ Toda equations. These solutions are obtained from time--like Kaluza--Klein reductions of $(3+2)$ solitons.Comment: 12 pages, to be published in Class.Quantum Gra

Infrared Search for Young Stars in HI High-velocity Clouds

We have searched the IRAS Point Source Catalog and HIRES maps for young stellar objects (YSOs) in the direction of five \HI high-velocity clouds (HVCs). In agreement with optical searches in the halo, no evidence was found for extensive star-forming activity inside the high-latitude HVCs. Specifically, we have found no signs of star formation or YSOs in the direction of the A IV cloud or in the very-high-velocity clouds HVC~110-7-465 and HVC~114-10-440. We have identified only one young star in the direction of the M~I.1 cloud, which shows almost perfect alignment with a knot of \HI emission. Because of the small number of early-type stars observed in the halo, the probability for such a positional coincidence is low; thus, this young star appears to be physically associated with the M~I.1 cloud. We have also identified a good YSO candidate in the \HI shell-like structure observed in the core region of the low-latitude cloud complex H (HVC~131+1-200). This region could be a supernova remnant with several other YSO candidates formed along the shock front produced by the explosion. In agreement with recent theoretical estimates, these results point to a low but significant star-formation rate in intermediate and high Galactic latitude HVCs. For M~I.1 in particular, we estimate that the efficiency of the star-formation process is M(YSO)/M(\HI)\ga 10^{-4}-10^{-3} by mass. Such efficiency is sufficient to account for (a) the existence of the few young blue stars whose ages imply that they were born in the Galactic halo, and (b) the nonprimordial metallicities inferred for some HVCs if their metal content proves to be low.Comment: 9 pages, 4 JPEG figures. PostScript figures available from author

Diode-switched thermal-transfer printed antenna on flexible substrate

We demonstrate that diode-switching can be used to introduce frequency agility into antennas produced by thermal transfer printing. Our particular example is a triangular Sierpinski fractal pattern with two PIN diodes to switch between operation optimised for the 800 MHz UHF band (diodes on) and the 2400 MHz ISM band (diodes off). Our measured results show an improvement in S11 in the UHF band from -2 dB to -28 dB, and from -7 dB to -30 dB at 2400 MHz, when switching the diodes appropriately. The measured bandwidth is 200 (1000) MHz, and the measured directivity is 3.1dB (5.2dB) while the measured gain is -5.2dB (6.7dB) for the diodes on(off)

Education of physical and rehabilitation medicine specialists across Europe: a call for harmonization

BACKGROUND: Physical and rehabilitation medicine (PRM) is well established in Europe and officially recognized by the European Union of Medical Specialists (UEMS). The European PRM Board works to promote patient safety and quality of care through the development of the highest standards of medical training and healthcare across Europe as well as the harmonization of PRM specialists' qualifications. In its Action Plan for 2014-2018, the UEMS PRM Board has included the harmonization of the PRM curriculum among the EU countries, as one of its main goals. Based on a European Directive, the Belgian Superior Council is envisaging a reform of the PRM curriculum. AIM: The aim of this paper is to present the current situation of PRM education in Europe according to the survey carried out by the Belgium Task Force. DESIGN: An online survey was posted on May 3rd 2015 to all delegates of the UEMS PRM Section and Board. Two questions were formulated: 1) What is the duration and curriculum of PRM training in your country? 2) Does a Postgraduate Rehabilitation training exist for other medical specialties? RESULTS: The majority of the PRM training programs in Europe have a duration ranging from 4 to 5 years, and are not aiming at downsizing the duration to the European minimal training period of 3 years. The vast majority (70%) of the responding countries don't offer an additional accreditation of Rehabilitation for other medical specialties CONCLUSIONS: Comparing PRM training programs in Europe can support the long-awaited reform of the PRM postgraduate curriculum in Belgium and gives perspective to agree on a transparent and comparable specialty training throughout Europe. Providing a more comparable training promotes the establishment of PRM and its rehabilitation service provisions in the world

Cauchy-characteristic Evolution of Einstein-Klein-Gordon Systems

A Cauchy-characteristic initial value problem for the Einstein-Klein-Gordon system with spherical symmetry is presented. Initial data are specified on the union of a space-like and null hypersurface. The development of the data is obtained with the combination of a constrained Cauchy evolution in the interior domain and a characteristic evolution in the exterior, asymptotically flat region. The matching interface between the space-like and characteristic foliations is constructed by imposing continuity conditions on metric, extrinsic curvature and scalar field variables, ensuring smoothness across the matching surface. The accuracy of the method is established for all ranges of $M/R$, most notably, with a detailed comparison of invariant observables against reference solutions obtained with a calibrated, global, null algorithm.Comment: Submitted to Phys. Rev. D, 16 pages, revtex, 7 figures available at http://nr.astro.psu.edu:8080/preprints.htm

Contributing to the growth of Physical and Rehabilitation Medicine (PRM): call for a Cochrane Field in PRM

The European Society of Physical and Rehabilitation Medicine (ESPRM), together with the European Journal of PRM and the PRM Section and Board of the European Union of Medical Specialists (UEMS), started an action to establish a relationship with Cochrane (formerl the Cochrane Collaboration). Cochrane is a global, independent network of researchers, professionals, patients, carers and people interested in health, with contributors from more than 130 countries. Its aim is to produce credible, accessible health information that is free from any conflicts of interest. Cochrane produces the Cochrane Ltbrary, an evidence-based resource that includes today more than 6300 Cochrane systematic reviews. Cochrane is made up of many different review groups and other entities (such as Centres and Branches), distnbuted around the world, that are mainly focused on specific healthcare problems (diseases, or organs). Inside Cochrane also Fields have been created, that focus on a dimension of health care other than a specific healthcare problem. A Cochrane Field represents a bridge between Cochrane and the stakeholders of the related healthcare area. The medical specialty of PRM is covering a broad medical domain: it deals with function, activities and participation in a large number of health conditions, mostly but not exclusively musculoskeletal, neurological and cardiorespiratory. Consequently, the currently more than 200 existing Cochrane Reviews are scattered among different groups. A PRM Field could greatly serve to the need of the specialty, spreading the actual Cochrane knowledge, focusing needs today not covered by Cochrane Reviews, facing the intrinsic methodological problems of the specialty. This paper introduces a call for the development of a PRM Cochrane Field, briefly reviewing what Cochrane is and how it is organized, defining the value and identifying a pathway toward the development of a PRM Cochrane Field, and finally shortly reviewing the Cochrane reviews of PRM interest