Vacuum thin shell solutions in five-dimensional Lovelock gravity

Junction conditions for vacuum solutions in five-dimensional Einstein-Gauss-Bonnet gravity are studied. We focus on those cases where two spherically symmetric regions of space-time are joined in such a way that the induced stress tensor on the junction surface vanishes. So a spherical vacuum shell, containing no matter, arises as a boundary between two regions of the space-time. Such solutions are a generalized kind of spherically symmetric empty space solutions, described by metric functions of the class $C^0$. New global structures arise with surprising features. In particular, we show that vacuum spherically symmetric wormholes do exist in this theory. These can be regarded as gravitational solitons, which connect two asymptotically (Anti) de-Sitter spaces with different masses and/or different effective cosmological constants. We prove the existence of both static and dynamical solutions and discuss their (in)stability under perturbations that preserve the symmetry. This leads us to discuss a new type of instability that arises in five-dimensional Lovelock theory of gravity for certain values of the coupling of the Gauss-Bonnet term.Comment: 9 pages. This is an extended version of the authors' contribution to the Proceedings of the Marcel Grossmann Meeting, held in Paris, 12-18 July 200

International Guillain-Barré Syndrome Outcome Study (IGOS): protocol of a prospective observational cohort study on clinical and biological predictors of disease course and outcome in Guillain-Barré syndrome

Guillain-Barré syndrome (GBS) is an acute polyradiculoneuropathy with a highly variable clinical presentation, course, and outcome. The factors that determine the clinical variation of GBS are poorly understood which complicates the care and treatment of individual patients. The protocol of the ongoing International GBS Outcome Study (IGOS), a prospective, observational, multi-centre cohort study that aims to identify the clinical and biological determinants and predictors of disease onset, subtype, course and outcome of GBS is presented here. Patients fulfilling the diagnostic criteria for GBS, regardless of age, disease severity, variant forms, or treatment, can participate if included within two weeks after onset of weakness. Information about demography, preceding infections, clinical features, diagnostic findings, treatment, course and outcome is collected. In addition, cerebrospinal fluid and serial blood samples for serum and DNA is collected at standard time points. The original aim was to include at least 1000 patients with a follow-up of 1-3 years. Data are collected via a web-based data entry system and stored anonymously. IGOS started in May 2012 and by January 2017 included more than 1400 participants from 143 active centres in 19 countries across 5 continents. The IGOS data/biobank is available for research projects conducted by expertise groups focusing on specific topics including epidemiology, diagnostic criteria, clinimetrics, electrophysiology, antecedent events, antibodies, genetics, prognostic modelling, treatment effects and long-term outcome of GBS. The IGOS will help to standardize the international collection of data and biosamples for future research of GBS. ClinicalTrials.gov Identifier: NCT01582763

A Lovelock black hole bestiary

We revisit the study of (A)dS black holes in Lovelock theories. We present a new tool that allows to attack this problem in full generality. In analyzing maximally symmetric Lovelock black holes with non-planar horizon topologies many distinctive and interesting features are observed. Among them, the existence of maximally symmetric vacua do not supporting black holes in vast regions of the space of gravitational couplings, multi-horizon black holes, and branches of solutions that suggest the existence of a rich diagram of phase transitions. The appearance of naked singularities seems unavoidable in some cases, raising the question about the fate of the cosmic censorship conjecture in these theories. There is a preferred branch of solutions for planar black holes, as well as non-planar black holes with high enough mass or temperature. Our study clarifies the role of all branches of solutions, including asymptotically dS black holes, and whether they should be considered when studying these theories in the context of AdS/CFT.Comment: 40 pages, 16 figures; v2: references added and minor amendments; v3: title changed to improve its accuracy and general reorganization of the results to ameliorate their presentatio

In-situ monitoring of etch by-products during reactive ion beam etching of GaAs in chlorine/argon

Mass spectrometry of the plasma effluent during Reactive Ion Beam Etching (RIBE) of GaAs using an Inductively Coupled Plasma (ICP) source and a Cl{sub 2}/Ar gas chemistry shows that AsCl{sub 3}, AsCl{sub 2} and AsCl are all detected as etch products for As, while GaCl{sub 2} is the main signal detected for the Ga products. The variation in selective ion currents for the various etch products has been examined as a function of chuck temperature (30--100 C), percentage Cl{sub 2} in the gas flow, beam current (60--180 mA) and beam voltage (200--800 V). The results are consistent with AsCl{sub 3} and GaCl{sub 3} being the main etch product species under their conditions, with fragmentation being responsible for the observed mass spectra

High-Density Plasma Etching of Group-III Nitride Films for Device Application

As III-V nitride device structures become more complicated and design rules shrink, well-controlled etch processes are necessary. Due to limited wet chemical etch results for the group-III nitrides, a significant amount of effort has been devoted to the development of dry etch processing. Dry etch development was initially focused on mesa structures where high etch rates, anisotropic profiles, smooth sidewalls, and equi-rate etching of dissimilar materials were required. For example, commercially available LEDs and laser facets for GaN-based laser diodes have been patterned using reactive ion etching (RIE). With the recent interest in high power, high temperature electronic devices, etch characteristics may also require smooth surface morphology, low plasma-induced damage, and selective etching of one layer over another. The principal criteria for any plasma etch process is its utility in the fabrication of a device. In this study, we will report plasma etch results for the group-III nitrides and their application to device structures

Guillain-Barré syndrome: a century of progress

In 1916, Guillain, Barré and Strohl reported on two cases of acute flaccid paralysis with high cerebrospinal fluid protein levels and normal cell counts — novel findings that identified the disease we now know as Guillain–Barré syndrome (GBS). 100 years on, we have made great progress with the clinical and pathological characterization of GBS. Early clinicopathological and animal studies indicated that GBS was an immune-mediated demyelinating disorder, and that severe GBS could result in secondary axonal injury; the current treatments of plasma exchange and intravenous immunoglobulin, which were developed in the 1980s, are based on this premise. Subsequent work has, however, shown that primary axonal injury can be the underlying disease. The association of Campylobacter jejuni strains has led to confirmation that anti-ganglioside antibodies are pathogenic and that axonal GBS involves an antibody and complement-mediated disruption of nodes of Ranvier, neuromuscular junctions and other neuronal and glial membranes. Now, ongoing clinical trials of the complement inhibitor eculizumab are the first targeted immunotherapy in GBS

A randomised controlled trial to compare opt-in and opt-out parental consent for childhood vaccine safety surveillance using data linkage: study protocol

Extent: 10p.Background: The Vaccine Assessment using Linked Data (VALiD) trial compared opt-in and opt-out parental consent for a population-based childhood vaccine safety surveillance program using data linkage. A subsequent telephone interview of all households enrolled in the trial elicited parental intent regarding the return or non-return of reply forms for opt-in and opt-out consent. This paper describes the rationale for the trial and provides an overview of the design and methods. Methods/Design: Single-centre, single-blind, randomised controlled trial (RCT) stratified by firstborn status. Mothers who gave birth at one tertiary South Australian hospital were randomised at six weeks post-partum to receive an opt-in or opt-out reply form, along with information explaining data linkage. The primary outcome at 10 weeks post-partum was parental participation in each arm, as indicated by the respective return or non-return of a reply form (or via telephone or email response). A subsequent telephone interview at 10 weeks post-partum elicited parental intent regarding the return or non-return of the reply form, and attitudes and knowledge about data linkage, vaccine safety, consent preferences and vaccination practices. Enrolment began in July 2009 and 1,129 households were recruited in a three-month period. Analysis has not yet been undertaken. The participation rate and selection bias for each method of consent will be compared when the data are analysed. Discussion: The VALiD RCT represents the first trial of opt-in versus opt-out consent for a data linkage study that assesses consent preferences and intent compared with actual opting in or opting out behaviour, and socioeconomic factors. The limitations to generalisability are discussed.Jesia G Berry, Philip Ryan, Annette J Braunack-Mayer, Katherine M Duszynski, Vicki Xafis, Michael S Gold, the Vaccine Assessment Using Linked Data (VALiD) Working Grou

Selective Etching Of Wide Bandgap Nitrides

HIGH-DENSITY PLASMA ETCHING HAS BEEN AN EFFECTIVE PATTERNING TECHNIQUE FOR THE GROUP-III NITRIDES DUE TO ION FLUXES WHICH ARE 2 TO 4 ORDERS OF MAGNITUDE HIGHER THAN MORE CONVENTIONAL REACTIVE ION ETCH (RIE) SYSTEMS. GAN ETCH RATES EXCEEDING 0.68 MICROMETER/MIN HAVE BEEN REPORTED IN C12/H2/AR INDUCTIVELY COUPLED PLASMAS (ICP) AT -280 V DC-BIAS. UNDER THESE CONDITIONS, THE ETCH MECHANISM IS DOMINATED BY ION BOMBARDMENT ENERGIES WHICH CAN INDUCE DAMAGE AND MINIMIZE ETCH SELECTIVITY. HIGH SELECTIVITY ETCH PROCESSES ARE OFTEN NECESSARY FOR HETEROSTRUCTURE DEVICES WHICH ARE BECOMING MORE PROMINENT AS GROWTH TECHNIQUES IMPROVE. IN THIS STUDY, WE WILL REPORT HIGH-DENSITY ICP ETCH RATES AND SELECTIVITIES FOR GAN, ALN, AND INN AS A FUNCTION OF CATHODE POWER, ICP-SOURCE POWER, AND CHAMBER PRESSURE. GAN:ALN SELECTIVITIES {gt} 8:1 were observed in a C12/Ar plasma at 10 mTorr pressure, 500 W ICP-source power, and 130 W cathode rf-power, while the GaN:InN selectivity was optimized at approx. 6.5:1 at 5 mTorr, 500 W ICP-source power, and 130 W cathode rf-power

Accuracy of prognosis estimates by four palliative care teams: a prospective cohort study

BACKGROUND: Prognosis estimates are used to access services, but are often inaccurate. This study aimed to determine the accuracy of giving a prognosis range. METHODS AND MEASUREMENTS: A prospective cohort study in four multi-professional palliative care teams in England collected data on 275 consecutive cancer referrals who died. Prognosis estimates (minimum – maximum) at referral, patient characteristics, were recorded by staff, and later compared with actual survival. RESULTS: Minimum survival estimates ranged <1 to 364 days, maximum 7 – 686 days. Mean patient survival was 71 days (range 1 – 734). In 42% the estimate was accurate, in 36% it was over optimistic and in 22% over pessimistic. When the minimum estimate was less than 14 days accuracy increased to 70%. Accuracy was related, in multivariate analysis, to palliative care team and (of borderline significance) patient age. CONCLUSIONS: Offering a prognosis range has higher levels of accuracy (about double) than traditional estimates, but is still very often inaccurate, except very close to death. Where possible clinicians should discuss scenarios with patients, rather than giving a prognosis range