Artificial dielectrics : characteristics at low and microwave frequencies

Artificial Dielectrics have been characterized using transmission line and s- parameter measurements. The complex dielectric constant and loss of graphite filled and non-poled piezoelectric-aggregate (Polyvinylidene Fluoride, PVDF) filled plastic (PMMA) has been characterized at low (1kHz-10kHz range, i.e., the VLF, very low frequency, range) and microwave frequencies. The average diameter diameter of graphite particles used was thirty microns. Measurements were performed on very fine graphite (one micron diameter grains) and 30 micron sized grains for comparison purposes. Fine grain graphite particles exhibited a, larger real dielectric constant, probably owing to a larger dipole effect. The dielectric constant characterization has also been done for PVDF-graphite-PMMA aggregates. Dissipation factors have been calculated in all cases. The very low frequency measurements have been done using lossy capacitance principles. The very low frequency behavior of graphite-PMMA. samples showed an anomaly at percolation point (about 15 % of graphite). PVDF-PMMA samples showed no anomaly within the range of concentration measured, probably owing to the fact that PVDF is a dielectric material. At microwave frequencies, it is found that both real and imaginary parts of the dielectric constant experience an increase with the increase in graphite/PVDF loading

Experimental and Numerical Investigation of Strength of Inertial Entrainment

Entrainment process can be seen both in natural and artificial events. Cyclonic winds and weather storms include stratified layer of air and water phases. Many turbulent weather conditions can be explained on the basis of entrainment. Different artificial purposes also utilize the phenomenon of entrainment. One of the examples is an educator pump. These pumps are used in ships to extract water in case of water leakage into the ship. The pump is used to remove the air and the water inside the ship is entrained out by the suction of the pump. Entrainment is used for air bubble entrapment in concrete. This helps to strengthen the concrete. Entrainment is also observed in the making of emulsion of one fluid in another, such as margarine. As for artificial processes with stratified liquid layers, the best examples metal extraction industries and nuclear reactors. In both cases gases are formed within liquid layers and cause entrainment. This is unwanted as entrainment causes mixing between two liquids. However in case of desalination plants and other places where mixing is desired, entrainment is enhanced purposely. The mixing of two fluids is generally done by bubbling gas through a tank containing the two fluids. These type of systems are called gas bubble stirred tanks

Large cerebello-pontine epidermoid tumor in a child

Cerebellopontine angle lesions are more commonly found in adults; however, they are uncommon in children. 13 year female child presented with progressive cerebellar signs and decreased hearing in left ear. Magnetic resonance imaging was suggestive of left cerebello-pontine angle epidermoid tumor that was treated surgically. In this rare case we discuss the imaging findings and review the relevant literature

A Prospective Study To Evaluate Medical Management Vs Surgical Intervention In Pain Relief And Healing Of Anal Fissure

Introduction: Anal fissure is a commonly encountered problem for surgeons. It is a longitudinal tear in distal anal canal with or without an ulcer. It causes significant changes in quality of life. This study was done to compare the efficacy of medical management and surgical intervention in cases of anal fissures. Methods: 50 patients were divided into two groups of 25 each. Group A patients were treated with topical application of 2% diltiazem gel and Group B patients were treated with Lateral sphincterotomy. Both groups were examined weekly for 4 weeks for pain using VAS score and at 12 weeks for healing. Results: 21(84%) patients were pain free after 4 weeks under Group A, 24 (96%) patients were pain free after 4 weeks under Group B. 22(88%) patients were completely healed at 12 weeks under Group A, 25(100%) patients were completely healed at 12 weeks under Group B. Conclusion: Lateral sphincterotomy can be advocated as treatment of choice for anal fissures. It has better pain relief and healing rates compared to topical application of 2% diltiazem gel. Medical Management can be used in patients refusing surgery or unfit for surger

Human Polycomb 2 Protein Is a SUMO E3 Ligase and Alleviates Substrate-Induced Inhibition of Cystathionine β-Synthase Sumoylation

Human cystathionine β-synthase (CBS) catalyzes the first irreversible step in the transsulfuration pathway and commits homocysteine to the synthesis of cysteine. Mutations in CBS are the most common cause of severe hereditary hyperhomocysteinemia. A yeast two-hybrid approach to screen for proteins that interact with CBS had previously identified several components of the sumoylation pathway and resulted in the demonstration that CBS is a substrate for sumoylation. In this study, we demonstrate that sumoylation of CBS is enhanced in the presence of human polycomb group protein 2 (hPc2), an interacting partner that was identified in the initial yeast two-hybrid screen. When the substrates for CBS, homocysteine and serine for cystathionine generation and homocysteine and cysteine for H2S generation, are added to the sumoylation mixture, they inhibit the sumoylation reaction, but only in the absence of hPc2. Similarly, the product of the CBS reaction, cystathionine, inhibits sumoylation in the absence of hPc2. Sumoylation in turn decreases CBS activity by ∼28% in the absence of hPc2 and by 70% in its presence. Based on these results, we conclude that hPc2 serves as a SUMO E3 ligase for CBS, increasing the efficiency of sumoylation. We also demonstrate that γ-cystathionase, the second enzyme in the transsulfuration pathway is a substrate for sumoylation under in vitro conditions. We speculate that the role of this modification may be for nuclear localization of the cysteine-generating pathway under conditions where nuclear glutathione demand is high

Functional Stability of Unliganded Envelope Glycoprotein Spikes among Isolates of Human Immunodeficiency Virus Type 1 (HIV-1)

The HIV-1 envelope glycoprotein (Env) spike is challenging to study at the molecular level, due in part to its genetic variability, structural heterogeneity and lability. However, the extent of lability in Env function, particularly for primary isolates across clades, has not been explored. Here, we probe stability of function for variant Envs of a range of isolates from chronic and acute infection, and from clades A, B and C, all on a constant virus backbone. Stability is elucidated in terms of the sensitivity of isolate infectivity to destabilizing conditions. A heat-gradient assay was used to determine T90 values, the temperature at which HIV-1 infectivity is decreased by 90% in 1 h, which ranged between ∼40 to 49°C (n = 34). For select Envs (n = 10), the half-lives of infectivity decay at 37°C were also determined and these correlated significantly with the T90 (p = 0.029), though two ‘outliers’ were identified. Specificity in functional Env stability was also evident. For example, Env variant HIV-1ADA was found to be labile to heat, 37°C decay, and guanidinium hydrochloride but not to urea or extremes of pH, when compared to its thermostable counterpart, HIV-1JR-CSF. Blue native PAGE analyses revealed that Env-dependent viral inactivation preceded complete dissociation of Env trimers. The viral membrane and membrane-proximal external region (MPER) of gp41 were also shown to be important for maintaining trimer stability at physiological temperature. Overall, our results indicate that primary HIV-1 Envs can have diverse sensitivities to functional inactivation in vitro, including at physiological temperature, and suggest that parameters of functional Env stability may be helpful in the study and optimization of native Env mimetics and vaccines

Global, regional, and national age-sex-specific mortality for 282 causes of death in 195 countries and territories, 1980-2017 : a systematic analysis for the Global Burden of Disease Study 2017

Background Global development goals increasingly rely on country-specific estimates for benchmarking a nation's progress. To meet this need, the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2016 estimated global, regional, national, and, for selected locations, subnational cause-specific mortality beginning in the year 1980. Here we report an update to that study, making use of newly available data and improved methods. GBD 2017 provides a comprehensive assessment of cause-specific mortality for 282 causes in 195 countries and territories from 1980 to 2017. Methods The causes of death database is composed of vital registration (VR), verbal autopsy (VA), registry, survey, police, and surveillance data. GBD 2017 added ten VA studies, 127 country-years of VR data, 502 cancer-registry country-years, and an additional surveillance country-year. Expansions of the GBD cause of death hierarchy resulted in 18 additional causes estimated for GBD 2017. Newly available data led to subnational estimates for five additional countries Ethiopia, Iran, New Zealand, Norway, and Russia. Deaths assigned International Classification of Diseases (ICD) codes for non-specific, implausible, or intermediate causes of death were reassigned to underlying causes by redistribution algorithms that were incorporated into uncertainty estimation. We used statistical modelling tools developed for GBD, including the Cause of Death Ensemble model (CODErn), to generate cause fractions and cause specific death rates for each location, year, age, and sex. Instead of using UN estimates as in previous versions, GBD 2017 independently estimated population size and fertility rate for all locations. Years of life lost (YLLs) were then calculated as the sum of each death multiplied by the standard life expectancy at each age. All rates reported here are age-standardised. Findings At the broadest grouping of causes of death (Level 1), non-communicable diseases (NC Ds) comprised the greatest fraction of deaths, contributing to 73.4% (95% uncertainty interval [UI] 72.5-74.1) of total deaths in 2017, while communicable, maternal, neonatal, and nutritional (CMNN) causes accounted for 186% (17.9-19.6), and injuries 8.0% (7.7-8.2). Total numbers of deaths from NCD causes increased from 2007 to 2017 by 22.7% (21.5-23.9), representing an additional 7.61 million (7. 20-8.01) deaths estimated in 2017 versus 2007. The death rate from NCDs decreased globally by 7.9% (7.08.8). The number of deaths for CMNN causes decreased by 222% (20.0-24.0) and the death rate by 31.8% (30.1-33.3). Total deaths from injuries increased by 2.3% (0-5-4-0) between 2007 and 2017, and the death rate from injuries decreased by 13.7% (12.2-15.1) to 57.9 deaths (55.9-59.2) per 100 000 in 2017. Deaths from substance use disorders also increased, rising from 284 000 deaths (268 000-289 000) globally in 2007 to 352 000 (334 000-363 000) in 2017. Between 2007 and 2017, total deaths from conflict and terrorism increased by 118.0% (88.8-148.6). A greater reduction in total deaths and death rates was observed for some CMNN causes among children younger than 5 years than for older adults, such as a 36.4% (32.2-40.6) reduction in deaths from lower respiratory infections for children younger than 5 years compared with a 33.6% (31.2-36.1) increase in adults older than 70 years. Globally, the number of deaths was greater for men than for women at most ages in 2017, except at ages older than 85 years. Trends in global YLLs reflect an epidemiological transition, with decreases in total YLLs from enteric infections, respirator}, infections and tuberculosis, and maternal and neonatal disorders between 1990 and 2017; these were generally greater in magnitude at the lowest levels of the Socio-demographic Index (SDI). At the same time, there were large increases in YLLs from neoplasms and cardiovascular diseases. YLL rates decreased across the five leading Level 2 causes in all SDI quintiles. The leading causes of YLLs in 1990 neonatal disorders, lower respiratory infections, and diarrhoeal diseases were ranked second, fourth, and fifth, in 2017. Meanwhile, estimated YLLs increased for ischaemic heart disease (ranked first in 2017) and stroke (ranked third), even though YLL rates decreased. Population growth contributed to increased total deaths across the 20 leading Level 2 causes of mortality between 2007 and 2017. Decreases in the cause-specific mortality rate reduced the effect of population growth for all but three causes: substance use disorders, neurological disorders, and skin and subcutaneous diseases. Interpretation Improvements in global health have been unevenly distributed among populations. Deaths due to injuries, substance use disorders, armed conflict and terrorism, neoplasms, and cardiovascular disease are expanding threats to global health. For causes of death such as lower respiratory and enteric infections, more rapid progress occurred for children than for the oldest adults, and there is continuing disparity in mortality rates by sex across age groups. Reductions in the death rate of some common diseases are themselves slowing or have ceased, primarily for NCDs, and the death rate for selected causes has increased in the past decade. Copyright (C) 2018 The Author(s). Published by Elsevier Ltd.Peer reviewe