ISAAC: Inflatable Satellite of an Antenna Array for Communications, volume 6

The results of a study to design an antenna array satellite using rigid inflatable structure (RIS) technology are presented. An inflatable satellite allows for a very large structure to be compacted for transportation in the Space Shuttle to the Space Station where it is assembled. The proposed structure resulting from this study is a communications satellite for two-way communications with many low-power stations on the ground. Total weight is 15,438 kilograms which is within the capabilities of the Space Shuttle. The satellite will have an equivalent aperture greater than 100 meters in diameter and will be operable in K and C band frequencies, with a total power requirement of 10,720 watts

Debye relaxation in high magnetic fields

Dielectric relaxation is universal in characterizing polar liquids and solids, insulators, and semiconductors, and the theoretical models are well developed. However, in high magnetic fields, previously unknown aspects of dielectric relaxation can be revealed and exploited. Here, we report low temperature dielectric relaxation measurements in lightly doped silicon in high dc magnetic fields B both parallel and perpendicular to the applied ac electric field E. For B//E, we observe a temperature and magnetic field dependent dielectric dispersion e(w)characteristic of conventional Debye relaxation where the free carrier concentration is dependent on thermal dopant ionization, magnetic freeze-out, and/or magnetic localization effects. However, for BperpE, anomalous dispersion emerges in e(w) with increasing magnetic field. It is shown that the Debye formalism can be simply extended by adding the Lorentz force to describe the general response of a dielectric in crossed magnetic and electric fields. Moreover, we predict and observe a new transverse dielectric response EH perp B perp E not previously described in magneto-dielectric measurements. The new formalism allows the determination of the mobility and the ability to discriminate between magnetic localization/freeze out and Lorentz force effects in the magneto-dielectric response.Comment: 19 pages, 6 figure

Properties of Pt Schottky Type Contacts On High-Resistivity CdZnTe Detectors

In this paper we present studies of the I-V characteristics of CdZnTe detectors with Pt contacts fabricated from high-resistivity single crystals grown by the high-pressure Brigman process. We have analyzed the experimental I-V curves using a model that approximates the CZT detector as a system consisting of a reversed Schottky contact in series with the bulk resistance. Least square fits to the experimental data yield 0.78-0.79 eV for the Pt-CZT Schottky barrier height, and <20 V for the voltage required to deplete a 2 mm thick CZT detector. We demonstrate that at high bias the thermionic current over the Schottky barrier, the height of which is reduced due to an interfacial layer between the contact and CZT material, controls the leakage current of the detectors. In many cases the dark current is not determined by the resistivity of the bulk material, but rather the properties of the contacts; namely by the interfacial layer between the contact and CZT material.Comment: 12 pages, 11 figure

Brain Imaging With Portable Low-Field MRI

The advent of portable, low-field MRI (LF-MRI) heralds new opportunities in neuroimaging. Low power requirements and transportability have enabled scanning outside the controlled environment of a conventional MRI suite, enhancing access to neuroimaging for indications that are not well suited to existing technologies. Maximizing the information extracted from the reduced signal-to-noise ratio of LF-MRI is crucial to developing clinically useful diagnostic images. Progress in electromagnetic noise cancellation and machine learning reconstruction algorithms from sparse k-space data as well as new approaches to image enhancement have now enabled these advancements. Coupling technological innovation with bedside imaging creates new prospects in visualizing the healthy brain and detecting acute and chronic pathological changes. Ongoing development of hardware, improvements in pulse sequences and image reconstruction, and validation of clinical utility will continue to accelerate this field. As further innovation occurs, portable LF-MRI will facilitate the democratization of MRI and create new applications not previously feasible with conventional systems

Findings from a pragmatic cluster randomised controlled feasibility trial of a music and dance programme for community dwelling older adults

IntroductionFunctional decline, chronic illness, reduced quality of life and increased healthcare utilisation are common in older adults. Evidence suggests music and dance can support healthy ageing in older adults. This study explored the feasibility, potential for effect and cost effectiveness of the Music and Movement for Health (MMH) programme among community-dwelling older adults using a pragmatic cluster-randomised, controlled feasibility trial design.MethodsCommunity-dwelling adults aged 65 years or older were recruited to seven clusters in the Mid-West region of Ireland. Clusters were block randomised to either the MMH intervention or control. Primary feasibility outcomes included recruitment, retention, adherence, fidelity, and safety. Secondary outcomes measured physical activity, physical and cognitive performance, and psychosocial well-being, along with healthcare utilisation were assessed at baseline and after 12 weeks.ResultsThe study successfully met feasibility targets, with recruitment (n = 100), retention (91 %), adherence (71 %), data completeness (92 %) and intervention fidelity (21 out of 24) all meeting predetermined criteria. Both groups exhibited an increase in self-reported physical activity and improved physical function. Participants in the intervention group scored consistently better in psychosocial measures compared to the control group at follow-up. The health economic analysis confirmed the feasibility of the methodology employed and points to the potential cost-effectiveness of the MMH relative to the control or no organised programme.Discussion and ImplicationsThe MMH intervention and study design were found to be feasible and acceptable with important findings to inform future evaluation of the clinical and cost-effectiveness of a definitive randomised controlled trial

Bipolar spintronics: From spin injection to spin-controlled logic

An impressive success of spintronic applications has been typically realized in metal-based structures which utilize magnetoresistive effects for substantial improvements in the performance of computer hard drives and magnetic random access memories. Correspondingly, the theoretical understanding of spin-polarized transport is usually limited to a metallic regime in a linear response, which, while providing a good description for data storage and magnetic memory devices, is not sufficient for signal processing and digital logic. In contrast, much less is known about possible applications of semiconductor-based spintronics and spin-polarized transport in related structures which could utilize strong intrinsic nonlinearities in current-voltage characteristics to implement spin-based logic. Here we discuss the challenges for realizing a particular class of structures in semiconductor spintronics: our proposal for bipolar spintronic devices in which carriers of both polarities (electrons and holes) contribute to spin-charge coupling. We formulate the theoretical framework for bipolar spin-polarized transport, and describe several novel effects in two- and three-terminal structures which arise from the interplay between nonequilibrium spin and equilibrium magnetization.Comment: 16 pages, 7 figure

Molecular evidence of Rickettsia felis infection in dogs from northern territory, Australia

The prevalence of spotted fever group rickettsial infection in dogs from a remote indigenous community in the Northern Territory (NT) was determined using molecular tools. Blood samples collected from 130 dogs in the community of Maningrida were subjected to a spotted fever group (SFG)-specific PCR targeting the ompB gene followed by a Rickettsia felis-specific PCR targeting the gltA gene of R. felis. Rickettsia felis ompB and gltA genes were amplified from the blood of 3 dogs. This study is the first report of R. felis infection in indigenous community dogs in NT

Effectiveness of telephone-based interventions for managing osteoarthritis and spinal pain: a systematic review and meta-analysis

Background Osteoarthritis and spinal pain are common and burdensome conditions; however, the majority of patients with these conditions do not receive care that is consistent with clinical practice guidelines. Telehealth models of care have the potential to improve care for osteoarthritis and spinal pain patients. The aim of this review was to assess the effectiveness of verbal real-time telehealth interventions, including telephone-based and videoconferencing interventions to reduce pain intensity and disability in patients with osteoarthritis of the knee or hip and spinal pain (back or neck pain). Methods We searched seven electronic databases from inception to May 2018. Randomised controlled trials (RCTs), cluster-RCTs, and non-randomised controlled trials were included. Two review authors independently extracted data for each included study. Primary outcomes were pain intensity and disability. We conducted primary meta-analyses combining all conditions with similar interventions and comparators. Standardised mean difference (SMD) and 95% confidence intervals (CIs) were calculated using random effects models. We used the Cochrane Risk of Bias tool to assess risk of bias, and GRADE to evaluate the quality of evidence. Results We included 23 studies with 56 trial arms and 4,994 participants. All studies utilised telephone-based interventions. Only two studies used a telephone only approach and the remainder included educational materials and/or face-to-face components. We found no studies utilising videoconferencing. Meta-analysis showed telephone-based interventions (with educational materials) for osteoarthritis and spinal pain improved pain intensity (n = 5 trials, n = 1,357 participants, SMD −0.27, 95% CI [−0.53, −0.01], Tau2 = 0.06, I2 = 74%; moderate-quality evidence) and disability (n = 7 trials, n = 1,537 participants, SMD −0.21, 95% CI [−0.40, −0.02], Tau2 = 0.03, I2 = 56%; moderate-quality evidence) compared to usual care. Meta-analyses found telephone with face-to-face interventions does not improve pain and disability compared to usual care or face-to-face care alone. Discussion We are moderately confident that telephone-based interventions reduce pain intensity and disability in patients with osteoarthritis and spinal pain compared to usual care, but telephone plus face-to-face interventions are no more effective than usual care or face-to-face interventions alone