Charge separation instability in an unmagnetized disk plasma around a Kerr black hole

In almost all of plasma theories for astrophysical objects, we have assumed the charge quasi-neutrality of unmagnetized plasmas in global scales. This assumption has been justified because if there is a charged plasma, it induces electric field which attracts the opposite charge, and this opposite charge reduces the charge separation. Here, we report a newly discovered instability which causes a charge separation in a rotating plasma inside of an innermost stable circular orbit (ISCO) around a black hole. The growth rate of the instability is smaller than that of the disk instability even in the unstable disk region and is forbidden in the stable disk region outside of the ISCO. However, this growth rate becomes comparable to that of the disk instability when the plasma density is much lower than a critical density inside of the ISCO. In such case, the charge separation instability would become apparent and cause the charged accretion into the black hole, thus charge the hole up.Comment: 15pages, 1 figur

Materials, Structures and Manufacturing: An Integrated Approach to Develop Expandable Structures

Membrane dominated space structures are lightweight and package efficiently for launch; however, they must be expanded (deployed) in-orbit to achieve the desired geometry. These expandable structural systems include solar sails, solar power arrays, antennas, and numerous other large aperture devices that are used to collect, reflect and/or transmit electromagnetic radiation. In this work, an integrated approach to development of thin-film damage tolerant membranes is explored using advanced manufacturing. Bio-inspired hierarchical structures were printed on films using additive manufacturing to achieve improved tear resistance and to facilitate membrane deployment. High precision, robust expandable structures can be realized using materials that are both space durable and processable using additive manufacturing. Test results show this initial work produced higher tear resistance than neat film of equivalent mass. Future research and development opportunities for expandable structural systems designed using an integrated approach to structural design, manufacturing, and materials selection are discussed

Experiences of living with chronic back pain: The physical disabilities

Purpose. Back-related functional limitations are largely assessed using lists of activities, each scored on a yes/no basis and the scores then summed. This provides little information about how chronic back pain (CBP) patients live with their condition. This study describes the consequences of living day-to-day with CBP and documents the 'insider' accounts of its impact on daily life. Method. Unstructured interviews, using the 'Framework' approach with topic guide, were recorded and transcribed verbatim. Subjects were sampled for age, sex, ethnicity and occupation from new referrals with back pain to a rheumatology outpatient clinic. Eleven subjects (5 male, 6 female) were interviewed either in English (n = 9) or their preferred language (n = 2). Interviews were read in-depth twice to identify the topics. Data were extracted in phrases and sentences using thematic content analysis. Results. Four themes emerged: sleep/rest, mobility, independence and leisure. All subjects reported issues about sleep and rest, nine about mobility, seven about independence and six on leisure. Most descriptions concerned loss and limitation in daily life. Strategies for coping with sleep disruption and physical limitations were described. Conclusions. Subjects provided graphic 'in-depth' descriptions of experiences living with CBP every day; expressed regret at the loss of capabilities and distress at the functional consequences of those losses. Facilitating 'adjustment' to 'loss' may be more helpful than inferring the potential for a life free of pain as a result of therapeutic endeavours

Covariant Formulation of the Transition Radiation Energy Spectrum of an Electron Beam at a Normal Angle of Incidence onto a Round Metallic Screen

In the transition radiation emission from a N electron bunch hitting at a normal angle of incidence a metallic screen, the transverse and the longitudinal spatial coordinates of the electron bunch play different roles in determining the N single electron radiation field amplitudes and their relative phases in relation to the different physical constraints which an electromagnetic radiative mechanism by a charged beam must meet: i.e., temporal causality and covariance. The distribution of the N electron longitudinal coordinates determines indeed the sequence of the N electron collisions onto the metallic screen and, on the basis of the temporal causality principle, it also determines the distribution function of the relative emission phases of the N single electron field amplitudes from the metallic surface. The distribution of the transverse coordinates of the N electrons contributes as well to determine the relative phase distribution of the N electron field amplitudes at the observation point - located on the longitudinal axis of the reference frame - providing a further phase information that accounts for the transverse displacement of the N electrons with respect to the beam axis. The distribution of the transverse coordinates of the N electrons is a relativistic invariant under a Lorentz transformation with respect to the direction of motion of the beam and, consequently, it is expected to leave a covariant mark on the N single electron amplitudes composing the radiation field. The covariant imprinting of the N electron transverse density on the radiation field affects both the temporal coherent and incoherent parts of the transition radiation energy spectrum. Such a dependence of the N single electron radiation field amplitudes on the electron density in the transverse plane manifests itself as....(abstract partially missed because of lack of space

GetREAL Intervention Manual. A staff training intervention for inpatient mental health rehabilitation units aimed at increasing patients’ engagement in activities

This intervention is designed to be carried out by a small team of experts who work for a short period of time with local staff in mental health rehabilitation units in England. The aim of the intervention is to develop local staff’s work with service users in these units in order for them to be increasingly engaged in activities of their choice and to increase their activity levels. The GetREAL Intervention Manual details the approaches, stages, actions and tools for the intervention

Ethics of sham surgery: Perspective of patients

Sham surgery is used as a control condition in neurosurgical clinical trials in Parkinson's disease (PD) but remains controversial. This study aimed to assess the perspective of patients with PD and the general public on the use of sham surgery controls. We surveyed consecutive patients from a university-based neurology outpatient clinic and a community-based general internal medicine practice. Background information was provided regarding PD and two possible methods of testing the efficacy of a novel gene transfer procedure, followed by questions that addressed participants' opinions related to the willingness to participate and permissibility of blinded and unblinded trial designs. Two hundred eighty-eight (57.6%) patients returned surveys. Patients with PD expressed less willingness to participate in the proposed gene transfer surgery trials. Unblinded studies received greater support, but a majority would still allow the use of sham surgery. Those in favor of sham surgery were more educated and more likely to use societal perspective rationales. Patients with PD are more cautious about surgical research participation than patients with non-PD. Their policy views were similar to others', with a majority supporting the use of sham controls. Future research needs to determine whether eliciting more considered judgments of laypersons would reveal different levels of support for sham surgery. © 2007 Movement Disorder SocietyPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/57916/1/21775_ftp.pd

Sham surgery controls in Parkinson's disease clinical trials: Views of participants

Background: Sham surgery controls are increasingly used in neurosurgical clinical trials in Parkinson's disease (PD) but remain controversial. We interviewed participants of such trials, specifically examining their understanding and attitudes regarding sham surgery. Methods: We conducted semistructured qualitative interviews with participants of 3 sham surgery–controlled trials for PD, focusing on their understanding of sham design, their reactions to it, its impact on decision making, and their understanding of posttrial availability of the experimental intervention and its impact on decisions to participate. Results: All subjects (n = 90) understood the 2‐arm design; most (86%) described the procedural differences between the arms accurately. Ninety‐two percent referred to scientific or regulatory reasons as rationales for the sham control, with 62% specifically referring to the placebo effect. Ninety‐one percent said posttrial availability of the experimental intervention had a strong (48%) or some (43%) influence on their decision to participate, but only 68% understood the conditions for posttrial availability. Conclusions: Most subjects in sham surgery–controlled PD trials comprehend the sham surgery design and its rationale. Although there is room for improvement, most subjects of sham surgery trials appear to be adequately informed. © 2012 Movement Disorder SocietyPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/93771/1/25155_ftp.pd