482 research outputs found

    Effect of an oxide cap layer and fluorine implantation on the metal-induced lateral crystallization of amorphous silicon

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    In this work, we investigate the effect of oxide cap layer on the metal-induced lateral crystallization (MILC) of amorphous silicon. The MILC is characterized at temperatures in the range 550 to 428°C using Nomarski optical microscopy and Raman spectroscopy. It is shown that better lateral crystallization is obtained when the oxide cap layer is omitted, with the crystallization length increasing by 33% for a 15 hour anneal at 550°C. A smaller increase of about 10% is seen at lower temperatures between 525°C and 475°C and no increase is seen below 450°C. It is also shown that the detrimental effect of the oxide cap layer can be dramatically reduced by giving samples a fluorine implant prior to the MILC anneal. Raman spectroscopy shows that random grain growth is significantly less for unimplanted samples without an oxide cap and also for fluorine implanted samples both with and without an oxide cap. The crystallization length improvement for samples without an oxide cap layer is explained by the elimination of random grain crystallization at the interface between the amorphous silicon and the oxide cap layer

    Electrical properties of Al-In-Sn alloys directionally solidified in high and low gravitational fields

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    The Al-In-Sn alloys were directionally solidified in the NASA KC-135 aircraft which flies a series of parabolas to generate high (high-g) and low (low-g) gravity forces parallel to the longitudinal growth axis. Thus, for a given sample, successive sections can be identified which were solidified in high-g and low-g. Measurements of the electronic properties of the samples reveal that: the resistivity of the low-g sections is larger (about a factor of 10) than that of the high-g sections; the low-g sections behave conductively like a semi-metal, while the high-g sections are essentially metallic; and both high-g and low-g sections are superconducting but the superconducting transition temperature of the low-g sections is 1 K higher than that of the high-g sections

    Self-aligned silicidation of surround gate vertical MOSFETs for low cost RF applications

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    We report for the first time a CMOS-compatible silicidation technology for surround-gate vertical MOSFETs. The technology uses a double spacer comprising a polysilicon spacer for the surround gate and a nitride spacer for silicidation and is successfully integrated with a Fillet Local OXidation (FILOX) process, which thereby delivers low overlap capacitance and high drive-current vertical devices. Silicided 80-nm vertical n-channel devices fabricated using 0.5-?m lithography are compared with nonsilicided devices. A source–drain (S/D) activation anneal of 30 s at 1100 ?C is shown to deliver a channel length of 80 nm, and the silicidation gives a 60% improvement in drive current in comparison with nonsilicided devices. The silicided devices exhibit a subthreshold slope (S) of 87 mV/dec and a drain-induced barrier lowering (DIBL) of 80 mV/V, compared with 86 mV/dec and 60 mV/V for nonsilicided devices. S-parameter measurements on the 80-nm vertical nMOS devices give an fT of 20 GHz, which is approximately two times higher than expected for comparable lateral MOSFETs fabricated using the same 0.5-?m lithography. Issues associated with silicidation down the pillar sidewall are investigated by reducing the activation anneal time to bring the silicided region closer to the p-n junction at the top of the pillar. In this situation, nonlinear transistor turn-on is observed in drain-on-top operation and dramatically degraded drive current in source-on-top operation. This behavior is interpreted using mixed-mode simulations, which show that a Schottky contact is formed around the perimeter of the pillar when the silicided contact penetrates too close to the top S/D junction down the side of the pillar

    Effects of augmented exercise therapy time after stroke: a meta-analysis

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    <p><b>Background and Purpose:</b> To present a systematic review of studies that addresses the effects of intensity of augmented exercise therapy time (AETT) on activities of daily living (ADL), walking, and dexterity in patients with stroke.</p> <p><b>Summary of Review:</b> A database of articles published from 1966 to November 2003 was compiled from MEDLINE, CINAHL, Cochrane Central Register of Controlled Trials, PEDro, DARE, and PiCarta using combinations of the following key words: stroke, cerebrovascular disorders, physical therapy, physiotherapy, occupational therapy, exercise therapy, rehabilitation, intensity, dose–response relationship, effectiveness, and randomized controlled trial. References presented in relevant publications were examined as well as abstracts in proceedings. Studies that satisfied the following selection criteria were included: (1) patients had a diagnosis of stroke; (2) effects of intensity of exercise training were investigated; and (3) design of the study was a randomized controlled trial (RCT). For each outcome measure, the estimated effect size (ES) and the summary effect size (SES) expressed in standard deviation units (SDU) were calculated for ADL, walking speed, and dexterity using fixed and random effect models. Correlation coefficients were calculated between observed individual effect sizes on ADL of each study, additional time spent on exercise training, and methodological quality. Cumulative meta-analyses (random effects model) adjusted for the difference in treatment intensity in each study was used for the trials evaluating the effects of AETT provided. Twenty of the 31 candidate studies, involving 2686 stroke patients, were included in the synthesis. The methodological quality ranged from 2 to 10 out of the maximum score of 14 points. The meta-analysis resulted in a small but statistically significant SES with regard to ADL measured at the end of the intervention phase. Further analysis showed a significant homogeneous SES for 17 studies that investigated effects of increased exercise intensity within the first 6 months after stroke. No significant SES was observed for the 3 studies conducted in the chronic phase. Cumulative meta-analysis strongly suggests that at least a 16-hour difference in treatment time between experimental and control groups provided in the first 6 months after stroke is needed to obtain significant differences in ADL. A significant SES supporting a higher intensity was also observed for instrumental ADL and walking speed, whereas no significant SES was found for dexterity.</p> <p><b>Conclusion:</b> The results of the present research synthesis support the hypothesis that augmented exercise therapy has a small but favorable effect on ADL, particularly if therapy input is augmented at least 16 hours within the first 6 months after stroke. This meta-analysis also suggests that clinically relevant treatment effects may be achieved on instrumental ADL and gait speed.</p&gt

    Turbulence and Mountain Wave Conditions Observed with an Airborne 2-Micron Lidar

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    Joint efforts by the National Aeronautics and Space Administration, the Department of Defense, and industry partners are enhancing the capability of airborne wind and turbulence detection. The Airborne Coherent Lidar (light detection and ranging) for Advanced In-Flight Measurements was flown on three series of flights to assess its capability over a range of altitudes, air mass conditions, and gust phenomena. This report describes the observation of mountain waves and turbulence induced by mountain waves over the Tehachapi and Sierra Nevada mountain ranges by lidar on board the NASA Airborne Science DC-8 (McDonnell Douglas Corporation, Long Beach, California) airplane during two flights. The examples in this report compare lidar-predicted mountain waves and wave-induced turbulence to subsequent airplane-measured true airspeed. Airplane acceleration data is presented describing the effects of the wave-induced turbulence on the DC-8 airplane. Highlights of the lidar-predicted airspeed from the two flights show increases of 12 m/s at the mountain wave interface and peak-to-peak airspeed changes of 10 m/s and 15 m/s in a span of 12 s in moderate turbulence

    'Staying safe' – A narrative review of falls prevention in people with Parkinson’s -'PDSAFE'

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    This is the author accepted manuscript. The final version is available from Taylor & Francis via the DOI in this record.Background: Parkinson's disease demonstrates a spectrum of motor and non-motor symptoms. Falling is common and disabling. Current medical management shows minimal impact to reduce falls, or fall related risk factors such as deficits in gait, strength and postural instability. Despite evidence supporting rehabilitation in reducing fall risk factors, the most appropriate intervention to reduce overall fall rate remains inconclusive. This paper aims to 1) synthesise current evidence and conceptual models of falls rehabilitation in Parkinson's in a narrative review; and based on this evidence 2) introduce the treatment protocol used in the falls prevention, multi-centre clinical trial 'PDSAFE'. Method: Search of four bibliographic databases using the terms ‘Parkinson*’ and ‘Fall*’ combined with each of the following; ‘Rehab*, Balanc*, Strength*, Strateg*and Exercis*' and a framework for narrative review was followed. 3557 papers were identified, 416 were selected for review. The majority report the impact of rehabilitation on isolated fall risk factors. Twelve directly measure the impact on overall fall rate. Discussion: Results were used to construct a narrative review with conceptual discussion based on the 'International Classification of Functioning’, leading to presentation of the 'PDSAFE' intervention protocol. Conclusion: Evidence suggests training single, fall risk factors may not affect overall fall rate. Combining with behavioural and strategy training in a functional, personalised multi-dimensional model, addressing all components of the ‘International Classification of Functioning’ is likely to provide a greater influence on falls reduction. 'PDSAFE' is a multi-dimensional, physiotherapist delivered, individually tailored, progressive, home-based programme. It is designed with a strong evidence based approach and illustrates a model for the clinical delivery of the conceptual theory discussed.This project was funded by the National Institute for Health Research Health Technologies Assessment programme (project number 10/57/21). VG is supported by the National Institute of Health Research Collaboration for Applied Health Research and Care South West Peninsula.

    Cluster randomized evaluation of Adolescent Girls Empowerment Programme (AGEP): study protocol.

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    BACKGROUND: Adolescents in less developed countries such as Zambia often face multi-faceted challenges for achieving successful transitions through adolescence to early adulthood. The literature has noted the need to introduce interventions during this period, particularly for adolescent girls, with the perspective that such investments have significant economic, social and health returns to society. The Adolescent Girls Empowerment Programme (AGEP) was an intervention designed as a catalyst for change for adolescent girls through themselves, to their family and community. METHODS/DESIGN: AGEP was a multi-sectoral intervention targeting over 10,000 vulnerable adolescent girls ages 10-19 in rural and urban areas, in four of the ten provinces of Zambia. At the core of AGEP were mentor-led, weekly girls' group meetings of 20 to 30 adolescent girls participating over two years. Three curricula - sexual and reproductive health and lifeskills, financial literacy, and nutrition - guided the meetings. An engaging and participatory pedagogical approach was used. Two additional program components, a health voucher and a bank account, were offered to some girls to provide direct mechanisms to improve access to health and financial services. Embedded within AGEP was a rigorous multi-arm randomised cluster trial with randomization to different combinations of programme arms. The study was powered to assess the impact across a set of key longer-term outcomes, including early marriage and first birth, contraceptive use, educational attainment and acquisition of HIV and HSV-2. Baseline behavioural surveys and biological specimen collection were initiated in 2013. Impact was evaluated immediately after the program ended in 2015 and will be evaluated again after two additional years of follow-up in 2017. The primary analysis is intent-to-treat. Qualitative data are being collected in 2013, 2015 and 2017 to inform the programme implementation and the quantitative findings. An economic evaluation will evaluate the incremental cost-effectiveness of each component of the intervention. DISCUSSION: The AGEP program and embedded evaluation will provide detailed information regarding interventions for adolescent girls in developing country settings. It will provide a rich information and data source on adolescent girls and its related findings will inform policy-makers, health professionals, donors and other stakeholders. TRIAL REGISTRATION: ISRCTN29322231 . March 04 2016; retrospectively registered

    Chemical informatics uncovers a new role for moexipril as a novel inhibitor of cAMP phosphodiesterase-4 (PDE4)

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    PDE4 is one of eleven known cyclic nucleotide phosphodiesterase families and plays a pivotal role in mediating hydrolytic degradation of the important cyclic nucleotide second messenger, cyclic 3â€Č5â€Č adenosine monophosphate (cAMP). PDE4 inhibitors are known to have anti-inflammatory properties, but their use in the clinic has been hampered by mechanism-associated side effects that limit maximally tolerated doses. In an attempt to initiate the development of better-tolerated PDE4 inhibitors we have surveyed existing approved drugs for PDE4-inhibitory activity. With this objective, we utilised a high-throughput computational approach that identified moexipril, a well tolerated and safe angiotensin-converting enzyme (ACE) inhibitor, as a PDE4 inhibitor. Experimentally we showed that moexipril and two structurally related analogues acted in the micro molar range to inhibit PDE4 activity. Employing a FRET-based biosensor constructed from the nucleotide binding domain of the type 1 exchange protein activated by cAMP, EPAC1, we demonstrated that moexipril markedly potentiated the ability of forskolin to increase intracellular cAMP levels. Finally, we demonstrated that the PDE4 inhibitory effect of moexipril is functionally able to induce phosphorylation of the Hsp20 by cAMP dependent protein kinase A. Our data suggest that moexipril is a bona fide PDE4 inhibitor that may provide the starting point for development of novel PDE4 inhibitors with an improved therapeutic window

    Measuring the Quantum State of a Large Angular Momentum

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    We demonstrate a general method to measure the quantum state of an angular momentum of arbitrary magnitude. The (2F+1) x (2F+1) density matrix is completely determined from a set of Stern-Gerlach measurements with (4F+1) different orientations of the quantization axis. We implement the protocol for laser cooled Cesium atoms in the 6S_{1/2}(F=4) hyperfine ground state and apply it to a variety of test states prepared by optical pumping and Larmor precession. A comparison of input and measured states shows typical reconstruction fidelities of about 0.95.Comment: 4 pages, 6 figures, submitted to PR

    A multicentre, randomised controlled trial of PDSAFE, a physiotherapist-delivered fall prevention programme for people with Parkinson’s

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    This is the author accepted manuscript. The final version is available from BMJ Publishing Group via the DOI in this record.Objective: To estimate the effect of a physiotherapist-delivered fall-prevention programme for people with Parkinson’s (PwP). Methods: People at risk of falls with confirmed Parkinson’s were recruited to this multi-centre, pragmatic, investigator blind, individually randomised controlled trial with pre-specified sub-group analyses. 474 PwP (Hoehn and Yahr 1-4) were randomised: 238 allocated to a physiotherapy programme and 236 to control. All participants had routine care; the control group received a DVD about Parkinson’s and single advice session at trial completion. The intervention group (PDSAFE) had an individually tailored, progressive home-based fall-avoidance strategy training programme with balance and strengthening exercises. The primary outcome was risk of repeat-falling, collected by self-report monthly diaries, 0 to 6 months post-randomisation. Secondary outcomes included, Mini-BESTest for balance, chair stand test, Falls Efficacy, freezing of gait, health related quality of life (Euroqol EQ-5D), Geriatric Depression Scale, Physical Activity Scale for the Elderly and Parkinson’s disease Questionnaire, fractures and rate of near-falling. Results: Average age, 72 years and 266 (56%) were men. By 6 months 116 (55%) of the control group, and 125 (61.5%) of the intervention group reported repeat falls (controlled odds ratio 1.21, 95% confidence interval 0.74 to 1.98, P=0.447). Secondary sub-group analyses suggested a different response to the intervention between moderate and severe disease severity groups. Balance, falls efficacy and chair stand time improved with near-falls reduced in the intervention arm. Conclusion: PDSAFE did not reduce falling in this pragmatic trial of PwP. Other functional tasks improved and reduced fall rates were apparent among those with moderate disease.Department of HealthNational Institute for Health Research (NIHR
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