Computation of the tip vortex flowfield for advanced aircraft propellers

The tip vortex flowfield plays a significant role in the performance of advanced aircraft propellers. The flowfield in the tip region is complex, three-dimensional and viscous with large secondary velocities. An analysis is presented using an approximate set of equations which contains the physics required by the tip vortex flowfield, but which does not require the resources of the full Navier-Stokes equations. A computer code was developed to predict the tip vortex flowfield of advanced aircraft propellers. A grid generation package was developed to allow specification of a variety of advanced aircraft propeller shapes. Calculations of the tip vortex generation on an SR3 type blade at high Reynolds numbers were made using this code and a parametric study was performed to show the effect of tip thickness on tip vortex intensity. In addition, calculations of the tip vortex generation on a NACA 0012 type blade were made, including the flowfield downstream of the blade trailing edge. Comparison of flowfield calculations with experimental data from an F4 blade was made. A user's manual was also prepared for the computer code (NASA CR-182178)

User's manual for PEPSIG NASA tip vortex version

The tip vortex flowfield plays a significant role in the performance of advanced aircraft propellers. The flowfield in the tip region is complex, three-dimensional and viscous with large secondary velocities. A computer code was developed to predict the tip vortex flowfield of advanced aircraft propellers. This document is the user's manual. The analysis and a series of test cases are presented in NASA-CR-182179

Energy-resolved electron-spin dynamics at surfaces of p-doped GaAs

Electron-spin relaxation at different surfaces of p-doped GaAs is investigated by means of spin, time and energy resolved 2-photon photoemission. These results are contrasted with bulk results obtained by time-resolved Faraday rotation measurements as well as calculations of the Bir-Aronov-Pikus spin-flip mechanism. Due to the reduced hole density in the band bending region at the (100) surface the spin-relaxation time increases over two orders of magnitude towards lower energies. At the flat-band (011) surface a constant spin relaxation time in agreement with our measurements and calculations for bulk GaAs is obtained.Comment: 6 pages, 4 figure

Space construction system analysis. Part 2: Platform definition

The top level system requirements are summarized and the accompanying conceptual design for an engineering and technology verification platform (ETVP) system is presented. An encompassing statement of the system objectives which drive the system requirements is presented and the major mission and subsystem requirements are described with emphasis on the advanced communications technology mission payload. The platform design is defined and used as a reference configuration for an end to space construction analyses. The preferred construction methods and processes, the important interactions between the platform design and the construction system design and operation, and the technology development efforts required to support the design and space construction of the ETVP are outlined

Protocol study: Sexual and reproductive health knowledge, information-seeking behaviour and attitudes among Saudi women: A questionnaire survey of university students

Copyright © 2014 Farih et al.; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.Background - Sexual and reproductive health (SRH), a basic right for women worldwide, is infrequently researched in countries in the Middle East and North Africa (MENA). No empirical studies of SRH among Saudi women exist. This protocol describes a study to explore the SRH knowledge, information-seeking behaviour and attitudes of Saudi female university students. Methods/Design - This study will administer a questionnaire survey to female students at 13 universities in Riyadh, Saudi Arabia. The questionnaire was developed following a literature search to identify relevant content, with psychometrically tested tools used when available. The content layout and the wording and order of the questions were designed to minimize the risk of bias. The questionnaire has been translated into Arabic and piloted in preparation for administration to the study sample. Ethical approval for the study has been granted (reference no. QMREC2012/54). After questionnaire administration, the data will be collated, analysed and reported anonymously. The findings will be published in compliance with reporting guidelines for survey research. Discussion - This study will be the first to provide fundamental information concerning Saudi females university students SRH knowledge and information needs.King Abdullah Scholarship Program, Saudi Arabi

Super-resolution provided by the arbitrarily strong superlinearity of the blackbody radiation

Blackbody radiation is a fundamental phenomenon in nature, and its explanation by Planck marks a cornerstone in the history of Physics. In this theoretical work, we show that the spectral radiance given by Planck's law is strongly superlinear with temperature, with an arbitrarily large local exponent for decreasing wavelengths. From that scaling analysis, we propose a new concept of super-resolved detection and imaging: if a focused beam of energy is scanned over an object that absorbs and linearly converts that energy into heat, a highly nonlinear thermal radiation response is generated, and its point spread function can be made arbitrarily smaller than the excitation beam focus. Based on a few practical scenarios, we propose to extend the notion of super-resolution beyond its current niche in microscopy to various kinds of excitation beams, a wide range of spatial scales, and a broader diversity of target objects

High abundance of a single taxon (amphipods) predicts aquatic macrophyte biodiversity in prairie wetlands

Conservation programs often aim to protect the abundance of individual species and biodiversity simultaneously. We quantified relations between amphipod densities and aquatic macrophyte (large plants and algae) diversity to test a hypothesis that biodiversity can support high abundance of a single taxonomic group. Amphipods (Gammarus lacustris and Hyalella azteca) are key forage for waterfowl and are declining in the Prairie Pothole Region of North America. We sampled a large gradient of amphipod densities (0–7050 amphipods/m3) in 49 semi-permanent wetlands, and 50% of the study wetlands had high amphipod densities (\u3e 500 amphipods/m3). Generalized linear models revealed G. lacustris and H. azteca densities increased exponentially with macrophyte diversity indices. Further, H. azteca densities were greatest at moderate levels of submersed vegetation biomass. Community analyses showed both amphipod species were positively associated with diverse macrophyte assemblages and negatively associated with high coverage of cattails (Typha spp.), a taxon that creates monotypic stands, as well as bladderwort (Utricularia spp.), a carnivorous plant. Our results indicate that amphipods could be used as an umbrella species for protecting diverse macrophyte communities in semi-permanent and permanent wetlands of North America’s Prairie Pothole Region

Vocational perspectives after spinal cord injury

Objective: To give insight into the vocational situation several years after a traumatic spinal cord injury (SCI) and describe the personal experiences and unmet needs; to give an overview of health and functional status per type of SCI and their relationship with employment status. Design: Descriptive analysis of data from a questionnaire. Setting: Dutch rehabilitation centre with special department for patients with spinal cord injuries. Subjects: Fifty-seven patients with a traumatic SCI, aged 18-60 years, admitted to the rehabilitation centre from 1990 to 1998. Main measures: Questionnaire with items related to vocational outcome, job experiences, health and functional status. Results: Of 49 patients who were working at the moment of SCI 60% currently had a paid job. Vocational outcome was related to a higher educational level. A significant relation between the SCI-specific health and functional status and employment was not found. The respondents who changed to a new employer needed more time to resume work, but seemed more satisfied with the job and lost fewer working hours than those who resumed work with the same employer. In spite of reasonable to good satisfaction with the current work situation, several negative experiences and unmet needs were reported. Conclusions: Despite a high participation in paid work following SCI, the effort of the disabled worker to have and keep a job should not be underestimated

Guided self-help interventions for mental health disorders in children with neurological conditions: study protocol for a pilot randomised controlled

Background: Rates of mental health disorders are significantly greater in children with physical illnesses than in physically well children. Children with neurological conditions, such as epilepsy, are known to have particularly high rates of mental health disorders. Despite this, mental health problems in children with neurological conditions have remained under-recognised and under-treated in clinical settings. Evidence-based guided self-help interventions are efficacious in reducing symptoms of mental health disorders in children, but their efficacy in reducing symptoms of common mental health disorders in children with neurological conditions has not been investigated. We aim to pilot a guided self-help intervention for the treatment of mental health disorders in children with neurological conditions. Methods/design: A pilot randomised controlled trial with 18 patients with neurological conditions and mental health disorders will be conducted. Participants attending specialist neurology clinics at a National UK Children’s Hospital will be randomised to receive guided self-help for common mental health disorders or to a 12-week waiting list control. Participants in the treatment group will receive 10 sessions of guided self-help delivered over the telephone. The waiting list control group will receive the intervention after a waiting period of 12 weeks. The primary outcome measure is reduction in symptoms of mental health disorders. Exclusion criteria are limited to those at significant risk of harm to self or others, the presence of primary mental health disorder other than anxiety, depression or disruptive behaviour (e.g. psychosis, eating disorder, obsessive-compulsive disorder) or intellectual disability at a level meaning potential participants would be unable to access the intervention. The study has ethical approval from the Camden and Islington NHS Research Ethics Committee, registration number 14.LO.1353. Results will be disseminated to patients, the wider public, clinicians and researchers through publication in journals and presentation at conferences. Discussion: This is the first study to investigate guided self-help interventions for mental health problems in children with neurological conditions, a group which is currently under-represented in mental health research. The intervention is modular and adapted from an empirically supported cognitive behavioural treatment. The generalisability and broad inclusion criteria are strengths but may also lead to some weaknesses

Comparison of the Ionosphere During an SMC Initiating Substorm and an Isolated Substorm

In order to assess the effects of ionospheric feedback on different modes of energy transport in the magnetosphere, we investigate an isolated substorm and a steady magnetospheric convection (SMC) event with very similar solar wind drivers. The primary focus is on a comparison between the isolated substorm and the substorm that initiates the SMC. Auroral data from Polar UVI LBHl and LBHs, along with assimilative mapping of the ionosphere electrojet potential patterns are used as inputs to the global ionosphere‐thermosphere model to calculate conductances and Joule heating rates. Results from this study show that the conductances both before and during the events play a large role the ability of the magnetosphere to remain in steady driven state. The substorm that initiates the SMC event shows very different signatures in the ionosphere than isolated substorm; these signatures indicate that there is very weak substorm current wedge, or possibly a pseudo‐breakup.Key PointsPreconditioning of the ionosphere plays a role in which mode of transport the magnetosphere entersNo DP1 current system was found during the initiating substorm of steady magnetospheric convection event (SMC)The Hall conductance is much stronger during the initiating substorm of the SMC and throughout the SMC compared to the isolated substormPeer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/145386/1/jgra54300_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/145386/2/jgra54300.pd