Enhanced power system stability by coordinated PSS design [Correction]

A step-by-step coordinated design procedure for PSSs and AVRs in a strongly-coupled system is described. It is shown that it is possible to separate the design of individual PSSs and to separate the design of individual AVRs. Thereby, the designs of AVR and PSS devices at a given machine can be coordinated to achieve near optimal overall power system stability performance, including oscillation stability performance and transient stability performance. The proposed coordinated PSS/AVR design procedure is established within a frequency domain framework and serves as a most useful small-signal complement to established large-signal transient simulation studies

Two-dimensional leapfrog scheme for trajectories of relativistic charged particles in static axisymmetric electric and magnetic field

A method for the calculation of two-dimensional particle trajectories is proposed in this work. It makes use of the cylindrical symmetry and the simplification of the static electric field, so that there should be no systematic error for the centered large-orbit rotations nor for the acceleration or deceleration in a uniform electric field. The method also shows a lower error level than the standard Boris method in many cases. Typical applications of this method are for example, electron microscopes, electron guns and collectors of gyro-devices as well as of other vacuum tubes, which can be described in axisymmetric cylindrical coordinates. Besides, the proposed method enforces the conservation of canonical angular momentum by construction, which is expected to show its advantages in the simulation of cusp electron guns and other components relying on non-adiabatic transitions in the externally applied static magnetic field

Preliminary Antiplaque Efficacy of Aloe Vera Mouthwash on 4 Day Plaque Re -Growth Model: Randomized Control Trial

Background: Due to increasing resistance to antibiotics and rising incidence of oral diseases, there is a need for alternative treatment modalities to combat oral diseases. The aim of the present study was to access the effect of Aloe vera mouthwash on the dental plaque in the experimental period of 4 days and to compare it with the bench mark control chlorhexidine and placebo (saline water).Material and Methods: A total of 300 systemically healthy subjects were randomly allocated into 3 groups: Aloe vera mouthwash group (n=100), control group (=100)–chlorhexidene group and saline water-Placebo (n=100). To begin with, Gingival index (GI) and plaque index (PI) were recorded. Then, baseline plaque scores were brought to zero by professionally cleaning the teeth with scaling and polishing. After randomization of the participants into three groups they were refrained from regular mechanical oral hygiene measures. Subjects were asked to swish with respective mouthwash (Aloe vera mouthwash, 0.2% chlorhexidine gluconate mouthwash, or normal saline) as per therapeutic  dose for 4 days.Results: The results showed that Aloe vera mouthrinse is equally effective in reducing plaque as Chlorhexidine compared to placebo over a period of 4 days. There was a significant reduction on plaque in Aloe vera and chlorhexidine groups and no statistically significant difference was observed among them (p>0.05). Aloe vera mouthwash showed no side effects.Conclusion: The results of the present study indicated that Aloe vera may prove an effective mouthwash due to its ability in reducing dental plaque.Keywords: Mouthwash, plaque, chlorhexidin

Estimating epidemiological and economic burden and community derived disability weights for snake bite in Kerala: a study protocol

BACKGROUND: In India, lack of data and underreporting of cases and deaths due to snakebite makes it difficult to estimate its socio-economic burden. Previous studies measuring economic burden of snakebite in low-and-middle-income countries (LMICs) using different approaches have been conducted, but none in India. The proposed study aims to provide evidence on disability weights, epidemiological and economic burden due to snakebites in Kerala state, India. PROTOCOL: The study is a community based cross-sectional study recruiting victims of snakebite occurring over a 12 month period prior to start of the study , across Ernakulam district, Kerala state, India. For the community-derived disability weights,70 adult patients who were treated within a 3 month period prior to commencement of the study at Amrita Institute of Medical Sciences, Kochi or Little Flower Hospital, Angamaly would be interviewed. The study will measure annual incidence, mortality, treatment cost of snakebites along with community-derived disability weights for snakebites in Ernakulam district.. Standard methods for analysis and reporting of mortality, morbidity, Years of Lives Lost (YLL), Years lived with disability (YLD), disability weights, and costs of treatment will be calculated. The study will be started in April 2021 and is expected to be completed by July2021. DISCUSSION: This protocol is the first published for estimating epidemiological, economic burden and community derived disability weights for snakebites in India. Besides, the Global Burden of Disease has not attached a particular disability weight to snakebite and this would be an attempt to do so. The protocol has been developed using guidelines for cross-sectional studies, cost of illness studies and international guidelines for conducting community derived disability weights. The evidence generated by this study will contribute significantly to knowledge regarding the epidemiology, economic burden and community-derived disability weights for snakebites in India and other countries where incidence of snakebite is high

How to select representative geographical areas in mental health service research

The original publication is available at www.springerlink.co

Novel High-Frequency Electric Field Sweeping Concept for High-Power Gyrotron Collectors

Future fusion power plants will require for plasma heating and noninductive current drive high-power gyrotrons, each of which generates 2 MW of continuous-wave microwave power, while another 2 MW in the spent electron beam is dissipated as heat on the collector wall. In today’s 1-MW continuous-wave gyrotrons, collector coils superimpose an ac (10–50 Hz) magnetic field to sweep the hot spots of spent electrons over a large area. However, to double today’s power, it will also be critical to reduce the hot spot dwell time preventing significant increase of material fatigue. This can be achieved by increasing the sweeping frequency. However, a higher frequency magnetic field would hardly penetrate the metallic collector vessel due to eddy currents. Instead of magnetic field, sweeping with electric fields is proposed for the first time. The presented mechanism is capable to apply several orders higher sweeping frequency to reduce the periodic variation of temperature, and thus, the device lifetime can be extended

Gyrotron multistage depressed collector based on E × B drift concept using azimuthal electric field. II: Upgraded designs

Multistage Depressed Collectors (MDCs) are nontrivial for high-frequency gyrotrons. A basic conceptual design of an E x B MDC using azimuthal electric fields was proposed in Part I of this series. In the present work, several upgraded design proposals based on the basic one will be elaborated. These proposals will significantly reduce the back-stream of electrons, which was the main drawback of the basic design proposal. Another upgraded design proposal will shrink the length and maximal radius of the MDC to be only a fraction of its full-length version. A conceptual design of the final MDC proposal will be given at the end

Toward the First Continuous Wave Compatible Multistage Depressed Collector Design for High Power Gyrotrons

The multistage depressed collector (MDC) is essential to significantly increase the overall efficiency of the gyrotron. To date, a short pulse (SP) MDC prototype system has been manufactured and is currently under test. The long-term goal that makes the most sense is to use MDCs on 2-MW fusion gyrotrons in continuous wave (CW) operation. To achieve this, a CW MDC system based on the same physical principle as the SP system is designed and analyzed for the first time. The highlights of this design are the sweeping systems to keep the thermal loading within an acceptable limit when the MDC is operated in CW. In the present analysis, the expected performance and size of the new CW MDC design are compared with that of the SP MDC prototype and with the corresponding single-stage depressed collectors (SDCs) as a reference. In addition, the effects of thermal expansion in CW operation are analyzed and discussed

An assessment of validity and responsiveness of generic measures of health-related quality of life in hearing impairment

This article is made available through the Brunel Open Access Publishing Fund. This article is distributed under the terms of the Creative Commons Attribution License which permits any use, distribution, and reproduction in any medium, provided the original author(s) and the source are credited.Purpose: This review examines psychometric performance of three widely used generic preference-based measures, that is, EuroQol 5 dimensions (EQ-5D), Health Utility Index 3 (HUI3) and Short-form 6 dimensions (SF-6D) in patients with hearing impairments. Methods: A systematic search was undertaken to identify studies of patients with hearing impairments where health state utility values were measured and reported. Data were extracted and analysed to assess the reliability, validity (known group differences and convergent validity) and responsiveness of the measures across hearing impairments. Results: Fourteen studies (18 papers) were included in the review. HUI3 was the most commonly used utility measures in hearing impairment. In all six studies, the HUI3 detected difference between groups defined by the severity of impairment, and four out of five studies detected statistically significant changes as a result of intervention. The only study available suggested that EQ-5D only had weak ability to discriminate difference between severity groups, and in four out of five studies, EQ-5D failed to detected changes. Only one study involved the SF-6D; thus, the information is too limited to conclude on its performance. Also evidence for the reliability of these measures was not found. Conclusion: Overall, the validity and responsiveness of the HUI3 in hearing impairment was good. The responsiveness of EQ-5D was relatively poor and weak validity was suggested by limited evidence. The evidence on SF-6D was too limited to make any judgment. More head-to-head comparisons of these and other preference measures of health are required.Medical Research Counci