The statistics of particle velocities in dense granular flows

We present measurements of the particle velocity distribution in the flow of granular material through vertical channels. Our study is confined to dense, slow flows where the material shears like a fluid only in thin layers adjacent to the walls, while a large core moves without continuous deformation, like a solid. We find the velocity distribution to be non-Gaussian, anisotropic, and to follow a power law at large velocities. Remarkably, the distribution is identical in the fluid-like and solid-like regions. The velocity variance is maximum at the core, defying predictions of hydrodynamic theories. We show evidence of spatially correlated motion, and propose a mechanism for the generation of fluctuational motion in the absence of shear.Comment: Submitted to Phys. Rev. Let

Frequency Zooming Techniques for High Resolution Spectrum Analysis

Zooming or high resolution spectrum analysis over narrow spectral bands commonly employs Fast Fourier Transform. In this paper, various Zooming techniques are compared from the point of view of hardware implementation and complexityof computation

Power quality improvement by using photovoltaic based shunt active harmonic filter with Z-source inverter converter

Introduction. The major source of energy for a long time has been fossil fuels, however this has its drawbacks because of their scarcity, exhaustibility, and impossibility of reusing them. Presently, a shunt active harmonic filter-equipped two-stage solar photovoltaic system is showing off its performance shunt active harmonic filter. The global power system has been impacted by current harmonics during the most modern industrial revolution. Novelty. The proposed work is innovative, by adopting the hysteresis modulation mode with Z-source inverter to enhance the performance of the system. Furthermore, the shunt active harmonic filter also get assists in this system for better improvement in the quality of power. Purpose. By incorporating an impedance source inverter and a photovoltaic shunt active harmonic filter methods, harmonic issues are mitigated. Methods. Load compensation is one of the services that the shunt active harmonic filter offers, in addition to harmonic compensation, power factor correction, and many other functions. The current pulse width modulation voltage source inverter method is more expensive, requires two converters owing to its two-stage conversion, has significant switching losses, and has a low rate of the reaction. The new model, in which the voltage source inverter is substituted out for a Z-source inverter converter, has been developed in order to address the problems of the existing system. Results. Rather than using a hybrid of DC-DC and DC-AC converters, the suggested system uses a shunt active harmonic filter that is powered by a photovoltaic source using a Z-source inverter. Utilizing Z-source inverter helps to address the present issues with conventional configurations. Practical value. By using software MATLAB/Simulink, this photovoltaic shunt active harmonic filter technique is analyzed. Shunt active harmonic filter, which produces compensatory current from the reference current obtained as from main supply, is powered by the photovoltaic array.Вступ. Основним джерелом енергії довгий час були викопні види палива, проте це мало свої недоліки через їх дефіцит, вичерпність та неможливість їх повторного використання. В даний час двоступенева сонячна фотоелектрична система, обладнана активним шунтуючим фільтром гармонік, демонструє свої робочі характеристики шунтуючого активного фільтра гармонік. На глобальну енергетичну систему вплинули гармоніки струму під час найсучаснішої промислової революції. Новизна. Пропонована робота є інноваційною, оскільки вона використовує режим гістерезисної модуляції з інвертором Z-джерела для підвищення продуктивності системи. Крім того, шунтуючий активний фільтр гармонік також допомагає в цій системі для покращення якості електроенергії. Мета. Включення інвертора джерела імпедансу та методів активного фільтру гармонік із фотогальванічним шунтом знижує гармонійні проблеми. Методи. Компенсація навантаження – це одна з функцій, які шунтуючий активний фільтр гармонік пропонує на додаток до компенсації гармонік, корекції коефіцієнта потужності та багатьох інших функцій. Інверторний метод широтно-імпульсної модуляції струму дорожчий, вимагає двох перетворювачів через його двокаскадного перетворення, має значні втрати комутації і має низьку швидкість реакції. Нова модель, в якій інвертор джерела напруги замінює перетворювач інвертора Z-джерела, була розроблена для вирішення проблем існуючої системи. Результати. Замість використання гібрида перетворювачів постійного та змінного струму в запропонованій системі використовується активний шунтуючий фільтр гармонік, який живиться від фотоелектричного джерела з використанням інвертора Z-джерела. Використання інвертора з Z-джерелом допомагає вирішити проблеми з традиційними конфігураціями. Практична цінність. За допомогою програмного забезпечення MATLAB/Simulink аналізується метод активного фільтру гармонік фотоелектричного шунта. Шунтуючий активний фільтр придушення гармонік, який виробляє компенсаційний струм із опорного струму, отриманого від мережі, живиться від фотоелектричної батареї

Review Study on Larvicidal and Mosquito Repellent Activity of Volatile Oils Isolated from Medicinal Plants

Mosquito is a vector for serious human diseases like dengue fever, hemaorrhagic dengue fever and chikungunya, .yellow fever, malaria, filaria and encephalitis among these dengue, hemaorrhagic dengue and chikungunya are highly endemic diseases in Southeast Asian and African countries, causing millions of deaths each and every year. Mosquito repellents thus play a major role in preventing man-mosquito contact and there by minimize the chance of infections and its adverse effects. The development of resistance to chemical insecticides, results rebounding vectorial capacity. Synthetic repellents are chemicals which used worldwide for protection against mosquito-borne diseases and it adversely affects the environment by contaminating water, soil and air. There is an urgent need to find alternatives to the synthetic insecticides. Plants are rich source of alternative agents for control of mosquitoes and its vectors. Extracts and isolated compounds from different plant families have been evaluated for their promising larvicidal and mosquito repellent activities. Literature has documented that essential oils and extracts have been traditionally used as effective repellents. The essential oils whose repellent activities have been demonstrated, as well as the importance of the synergistic effects among their components are the main focus of this review study. Essential oils are volatile mixtures of hydrocarbons with a diversity of functional groups, and their repellent activity has been linked to the presence of monoterpenes and sesquiterpenes. The present review study focused the larvicidal potential and mosquito repellent activity of different volatile oils of medicinal plants. From an economical point of view synthetic chemical is still more frequently used as repellents than essential oils; these essential oils have the potential to provide efficient and can be used as a cheap, eco-friendly, safer for humans and the environment and also efficient alternative to the chemical larvicides

Appendicitis in pregnancy: management

Background:Acute appendicitis is an infrequent, yet one of the commonest surgical emergency encountered in pregnancy. Recorded incidence is about 1:1500 pregnancies. The aim of this study was to determine the risk factors associated with prenatal outcome in acute appendicitis during second and third trimester pregnancies. Open access surgery was done due to non-availability of laparoscopy.Methods:A total of 10 pregnant women who were diagnosed with acute appendicitis between Jan 2011 to Jan 2013 were presented and 7 of them operated by open access surgery.Results: Seven pregnant women who were diagnosed with acute appendicitis were operated upon during late pregnancy. The interval between symptom onset and surgery was the only predictive variable. A longer interval between symptom onset and surgery was associated with appendix perforation than with no appendix perforation. There was a significant difference in the rate of preterm labor (5.1% vs. 1.3%) and the rate of fetal mortality (25% vs. 1.7%) between patients with and without a perforated appendix.Conclusion:Delaying surgery correlates to more advanced disease with an increased risk of perforation. This contributes to an increased risk of further complications, including premature labor or abortion, and to higher maternal complication rates. Prompt diagnosis may improve the prenatal outcome.

Variabilidade de isolados de Magnaporthe oryzae em arroz irrigado no Brasil.

Objetivando rastrear a variabilidade genética de M. oryzae em regiões produtoras de arroz irrigado no Brasil, este trabalho foi realizado utilizando-se 18 marcadores microssatélites. Foram selecionados 235 isolados monospóricos obtidos de oito cultivares de arroz irrigado coletados em RS,TO, MS e SC , os quais tiveram seus patótipos determinados

Promoter polymorphism of IL-8 gene and IL-8 production in pulmonary tuberculosis

Interleukin-8 (IL-8) is a chemokine which functions as a potent chemo attractant for the recruitment of leucocytes to the inflammatory sites. A polymorphism in position –251 in the promoter region of the IL-8 gene has been shown to be associated with altered IL-8 production. IL-8-251A promoter polymorphism was studied in 127 pulmonary tuberculosis (PTB) patients and 124 normal healthy subjects (NHS). IL-8 gene variants were correlated with IL-8 levels from peripheral blood mononuclear cells stimulated with phytohaemagglutinin, culture filtrate antigen (CFA) of Mycobacterium tuberculosis and live M. tuberculosis. No difference was observed in the variant genotype frequencies of IL-8 gene and IL-8 levels between NHS and PTB patients. NHS positive for TT genotype showed a higher spontaneous IL-8 production than AA genotype (P = 0.05). Similarly, PTB patients with TT genotype showed significantly higher IL-8 production to CFA (P = 0.009) and live M. tuberculosis (P = 0.022), compared to patients with AA genotype. The study suggests that the variant genotypes of –251 promoter polymorphism of the IL-8 gene are not associated with susceptibility to PTB. Probably, TT genotype may be associated with higher IL-8 production and increased leucocyte accumulation and inflammation at the site of M. tuberculosis infection