"Test me and treat me" - attitudes to vitamin D deficiency and supplementation: a qualitative study

© 2015 BMJ Open, "Test me and treat me"-attitudes to vitamin D deficiency and supplementation: a qualitative study. This manuscript version is made available under the Creative Commons Attribution Licens

Voltage Stability Analysis of Grid-Connected Wind Farms with FACTS: Static and Dynamic Analysis

Recently, analysis of some major blackouts and failures of power system shows that voltage instability problem has been one of the main reasons of these disturbances and networks collapse. In this paper, a systematic approach to voltage stability analysis using various techniques for the IEEE 14-bus case study, is presented. Static analysis is used to analyze the voltage stability of the system under study, whilst the dynamic analysis is used to evaluate the performance of compensators. The static techniques used are Power Flow, V–P curve analysis, and Q–V modal analysis. In this study, Flexible Alternating Current Transmission system (FACTS) devices- namely, Static Synchronous Compensators (STATCOMs) and Static Var Compensators (SVCs) - are used as reactive power compensators, taking into account maintaining the violated voltage magnitudes of the weak buses within the acceptable limits defined in ANSI C84.1. Simulation results validate that both the STATCOMs and the SVCs can be effectively used to enhance the static voltage stability and increasing network loadability margin. Additionally, based on the dynamic analysis results, it has been shown that STATCOMs have superior performance, in dynamic voltage stability enhancement, compared to SVCs

Efficient error correcting scheme for chaos shift keying signals

An effective error-correction scheme based on normalized correlation for a non coherent chaos communication system with no redundancy bits is proposed in this paper. A modified logistic map is used in the proposed scheme for generating two sequences, one for every data bit value, in a manner that the initial value of the next chaotic sequence is set by the second value of the present chaotic sequence of the similar symbol. This arrangement, thus, has the creation of successive chaotic sequences with identical chaotic dynamics for error correction purpose. The detection symbol is performed prior to correction, on the basis of the suboptimal receiver which anchors on the computation of the shortest distance existing between the received sequence and the modified logistic map’s chaotic trajectory. The results of the simulation reveal noticeable Eb/No improvement by the proposed scheme over the prior to the error- correcting scheme with the improvement increasing whenever there is increase in the number of sequence N. Prior to the error-correcting scheme when N=8, a gain of 1.3 dB is accomplished in Eb/No at 10-3 bit error probability. On the basis of normalized correlation, the most efficient point in our proposed error correction scheme is the absence of any redundant bits needed with minimum delay procedure, in contrast to earlier method that was based on suboptimal method detection and correction. Such performance would render the scheme good candidate for applications requiring high rates of data transmission

An Improved M-ary Modulation Scheme Based on Chaotic Dynamics, Journal of Telecommunications and Information Technology, 2019, nr 4

This paper proposes an improved chaos-based M-ary modulation system. It reproduces deterministic chaotic dynamics to create M-ary non-coherent modulation. The proposed modulation system transmits data using autonomous chaotic sequences. It separates the chaotic dynamics through the use of interleavers and realigns them through the use deinterleavers. The simulation results show that the improved scheme overperforms its traditional counterpart. The degree of improvement grows as the M-ary order is increased, with a penalty of increased system complexit

Characteristics, Risk Factors, and Treatment Practices of Known Adult Hypertensive Patients in Saudi Arabia

Objective. To determine the prevalence, risk factors, characteristics, and treatment practices of known adult hypertensives in Saudi Arabia. Methods. Cross-sectional community-based study using the WHO stepwise approach. Saudi adults were randomly chosen from Primary Health Care Centers catchment areas. Data was collected using a questionnaire which included sociodemographic data, history of hypertension, risk factors, treatment practices, biochemical and anthropometric measurements. Collected data was cheeked, computer fed, and analysed using SPSS V17. Results. Out of 4719 subjects (99.2% response), 542 (11.5%) subjects were known hypertensives or detected by health workers in the past 12 months. Hypertension was significantly associated with age, gender, geographical location, education, employment, diabetes, physical inactivity, excess body weight, and ever smoking. Multiple logistic analysis controlling for age showed that significant predictors of hypertension were diabetes mellitus, ever smoking, obesity, and hypercholesteremia. Several treatment modalities and practices were significantly associated with gender, age, education, and occupation. About 74% were under prescribed treatment by physicians, 62% on dietary modification, 37% attempted weight reduction, 27% performed physical exercise, and less than 7% used herbs, consulted traditional healers or quitted smoking. Income was not significantly associated with any treatment modality or patient practices. Conclusion. Hypertension (known and undetected) is a major chronic health problem among adults in Saudi Arabia. Many patients' practices need changes. A comprehensive approach is needed to prevent, early detect, and control the disease targeting, the risk factors, and predictors identified

Characterizing human vestibular sensory epithelia for experimental studies: new hair bundles on old tissue and implications for therapeutic interventions in ageing.

Balance disequilibrium is a significant contributor to falls in the elderly. The most common cause of balance dysfunction is loss of sensory cells from the vestibular sensory epithelia of the inner ear. However, inaccessibility of inner ear tissue in humans severely restricts possibilities for experimental manipulation to develop therapies to ameliorate this loss. We provide a structural and functional analysis of human vestibular sensory epithelia harvested at trans-labyrinthine surgery. We demonstrate the viability of the tissue and labeling with specific markers of hair cell function and of ion homeostasis in the epithelium. Samples obtained from the oldest patients revealed a significant loss of hair cells across the tissue surface, but we found immature hair bundles present in epithelia harvested from patients >60 years of age. These results suggest that the environment of the human vestibular sensory epithelium could be responsive to stimulation of developmental pathways to enhance hair cell regeneration, as has been demonstrated successfully in the vestibular organs of adult mice

Visualization of positive and negative sense viral RNA for probing the mechanism of direct-acting antivirals against hepatitis C virus

RNA viruses are highly successful pathogens and are the causative agents for many important diseases. To fully understand the replication of these viruses it is necessary to address the roles of both positive-strand RNA ((+)RNA) and negative-strand RNA ((-)RNA), and their interplay with viral and host proteins. Here we used branched DNA (bDNA) fluorescence in situ hybridization (FISH) to stain both the abundant (+)RNA and the far less abundant (-)RNA in both hepatitis C virus (HCV)- and Zika virus-infected cells, and combined these analyses with visualization of viral proteins through confocal imaging. We were able to phenotypically examine HCV-infected cells in the presence of uninfected cells and revealed the effect of direct-acting antivirals on HCV (+)RNA, (-)RNA, and protein, within hours of commencing treatment. Herein, we demonstrate that bDNA FISH is a powerful tool for the study of RNA viruses that can provide insights into drug efficacy and mechanism of action

Design study for a laminar-flying-wing aircraft

The Greener by Design initiative has identified the laminar-flying-wing configuration as the most promising long-term prospect for fuel-efficient civil aviation. However, in the absence of detailed evaluations, its potential remains uncertain. As an initial contribution, this work presents a point design study for a specification chosen to maximize aerodynamic efficiency, via large wingspan and low sweepback. The resulting aircraft carries 220 passengers over a range of 9000 km at Mach 0.67 and has a lift-to-drag ratio of 60.9, far in excess of conventional passenger transports. However, its overall effectiveness is compromised by a high empty-to-payload weight ratio and, because of the huge discrepancy between cruise and climb-out thrust requirements, a poor engine efficiency. As a result, it has a much less marked fuel-consumption advantage (11.4–13.9 g per passenger kilometer, compared to 14.6) over a conventional competitor designed, using the same methods, for the same mission. Both weight ratio and engine efficiency could be improved by reducing aspect ratio, but at the cost of an aerodynamic efficiency penalty. This conflict, which has not previously been recognized, is inherent to the laminar-flying-wing concept and may undermine its attractiveness.This paper has benefited from the perceptive comments made by its reviewers, especially with regard to the influence of altitude on engine efficiency. The first author thanks the Engineering and Physical Sciences Research Council for financial support via its Doctoral Training scheme. Supporting research data are available at https://www.repository.cam.ac.uk/handle/1810/247199/browse?type=title.This is the author accepted manuscript. The final version is available from American Institute of Aeronautics and Astronautics via http://dx.doi.org/10.2514/1.C03286

The Attenuation Capability ofSelected Steel Alloys for Nuclear Reactor Applications

Neutronsand gamma ray attenuation of different steel grades (SS304, SS304L, SS316L, SS430, a modified high manganese-nitrogen austenitic stainless steel, and developed cobalt-free Maraging steel) was measured to study their capability to be used as nuclear reactor materials. The hardness and microstructure of the studied steel alloys were carried out using Vickers hardness and optical microscope respectively.Neutron and gamma rays measurements were carried out using a narrow beam transmissions geometry method. Measurements and calculations of gamma ray attenuation coefficients were carried out at energies 238.63, 338.28, 583.19, 911.2, 968.97, 1173.23, 1332.49, and 2614.51 keV. The transmitted gamma rays were detected by the Hyper Pure Germanium detector (HPGe), while, the neutron flux emitted from 241Am-Be neutron source was used to measure the neutron removal cross section for both slow and total neutrons. The transmitted beam of neutrons was measured under a good geometric conditions using 3He counter.A good agreement between experimental data of mass attenuation coefficients and theoretical results calculated by the WinXcom computer program (version 3.1) was obtained