Fate of the Universe, Age of the Universe, Dark Matter, and the Decaying Vacuum Energy

It is shown that in the cosmological models based on a vacuum energy decaying as a^{-2}, where a is the scale factor of the universe, the fate of the universe in regard to whether it will collapse in future or expand forever is determined not by the curvature constant k but by an effective curvature constant k_{eff}. It is argued that a closed universe with k=1 may expand forever, in other words simulate the expansion dynamics of a flat or an open universe because of the possibility that k_{eff}=0 or -1, respectively. Two such models, in one of which the vacuum does not interact with matter and in another of which it does, are studied. It is shown that the vacuum equation of state p_{vac}= -\rho_{vac} may be realized in a decaying vacuum cosmology provided the vacuum interacts wuth matter. The optical depths for gravitational lensing as a function of the matter density and other parameters in the models are calculated at a source redshift of 2. The age of the universe is discussed and shown to be compatible with the new Hipparcos lower limit of 11Gyr. The possibility that a time-varying vacuum energy may serve as dark matter is suggested.Comment: AAS LaTex, 29 pages, published in the Astrophysical Journal, 520, 45, 199

Double Inverse Stochastic Resonance with Dynamic Synapses

We investigate the behavior of a model neuron that receives a biophysically-realistic noisy post-synaptic current based on uncorrelated spiking activity from a large number of afferents. We show that, with static synapses, such noise can give rise to inverse stochastic resonance (ISR) as a function of the presynaptic firing rate. We compare this to the case with dynamic synapses that feature short-term synaptic plasticity, and show that the interval of presynaptic firing rate over which ISR exists can be extended or diminished. We consider both short-term depression and facilitation. Interestingly, we find that a double inverse stochastic resonance (DISR), with two distinct wells centered at different presynaptic firing rates, can appear.Comment: 12 pages, 7 figure

Intersectional Discrimination Is Associated with Housing Instability among Trans Women Living in the San Francisco Bay Area.

Trans women face numerous structural barriers to health due to discrimination. Housing instability is an important structural determinant of poor health outcomes among trans women. The purpose of this study was to determine if experiences of intersectional anti-trans and racial discrimination are associated with poor housing outcomes among trans women in the San Francisco Bay Area. A secondary analysis of baseline data from the Trans *National study (n = 629) at the San Francisco Department of Public Health (2016-2018) was conducted. Multivariable logistic regression was used to analyze the association between discrimination as an ordered categorical variable (zero, one to two, or three or more experiences) and housing status adjusting for age, years lived in the Bay Area, and gender identity. We found that the odds of housing instability increased by 1.25 for every categorical unit increase (1-2, or 3+) in reported experiences of intersectional (both anti-trans and racial) discrimination for trans women (95% CI = 1.01-1.54, p-value < 0.05). Intersectional anti-trans and racial discrimination is associated with increased housing instability among trans women, giving some insight that policies and programs are needed to identify and address racism and anti-trans stigma towards trans women. Efforts to address intersectional discrimination may positively impact housing stability, with potential for ancillary effects on increasing the health and wellness of trans women who face multiple disparities

Modeling and simulation of the ferroelectric based micro gyroscope: FEM analysis

Cataloged from PDF version of article.This paper presents the design and modeling of micro-electromechanical systems (MEMS) on the ternary ferroelectric compounds (PZT) based by using finite element model (FEM) simulation. The conceptual framework establishes five steps to perform the critical analysis: design a novel structure, define the failure mechanisms under the given conditions, analyze different vibrations, analyze the operation principle, and detect resonance modes. In addition, MEMS failure modes were analyzed under different scenarios and the obtained results discussed

A Research of nasal methicillin resistant/sensitive Staphylococcus aureus and pharyngeal beta-haemolytic Streptococcus carriage in midwifery students in Kahramanmaras, Eastern Mediterranean Region of Turkey

Background: In the hospitals where hygienic conditions are not provided, nasal methicillin resistant/sensitive Staphylococcus aureus (MRSA/MSSA) colonization is seen in the hospital personnel and patients. Both the individuals’ themselves being MRSA/MSSA carriers and also other people around them are under risk and this bacterium leads to nasal colonization and then can propagate through contaminated hands and hospital materials.Objective: In this study, it was aimed to research MRSA/MSSA and beta-haemolytic streptococcus (BHS) carriage in the nose and throat flora of students of, School of Health.Methods: In the study, total of 160 midwifery students taking midwifery education was included in the research but 135 (84.4 %) out of 160 students were able to be reached. The nose and throat swab samples taken from students were examined through microbiological methods.Results: 14.1 % of students were nasal MSSA carrier. While there wasn't the nasal MRSA carrier among students attending the study in the 1st and 2nd class, 3.3 % (1 person) of the 3rd class students and 10.0 % (3 people) of the 4th class students were the nasal MRSA carrier. In addition, BHS carriage was determined in 1.5 % of students and there wasn't any difference between classes.Conclusions: These results indicate that midwifery students might have been contaminated with MSSA/MRSA during clinical practice. That MSSA/MRSA being an important pathogen is seen in midwifery students taking education in the birth units threatens the mother-child health. [Ethiop. J. Health Dev. 2010;24(1):57-60

Reactive metal/graphene oxide doping to fabricate porous geopolymers for arsenic removal

Please click Additional Files below to see the full abstract

The Fatigue Strength of AISI 430—304 Stainless Steels Welded by CO₂ Laser Beam Welding

In this study, the fatigue strength of AISI 430—304 stainless steels welded by CO₂ laser beam welding (LBW) is investigated. Laser welding experiments are carried under helium atmosphere at 2000, 2250 and 2500 W welding powers with 100 cm/min welding speed. The welding zones are examined by optical microscopy, scanning electron microscopy, and energy dispersive spectroscopy analysis. Fatigue tests are performed using an axial fatigue test machine, and the fatigue strength is analysed drawing S−N curves and critically observing fatigue fracture surfaces of the tested samples. The experimental results indicate that mechanical properties and microstructural features are affected significantly by welding power. The fatigue strength of CO₂ laser welded samples increase due to higher deep penetration in welding zone with increasing welding power in chosen conditions. The best properties are observed with the specimens welded at 2500 W heat input and 100 cm/min welding speed.В цій роботі досліджено втомну міцність неіржавійних сталей AISI 430—304, зварених променем CO₂-лазера. Експерименти з лазерного зварювання виконувалися в атмосфері гелію за потужности зварювання у 2000, 2250 і 2500 Вт із швидкістю зварювання у 100 см/хв. Зони зварювання досліджувалися методами оптичної мікроскопії, сканівної електронної мікроскопії та енергодисперсійної спектроскопії. Дослідження на втому виконувалися з використанням машини для випробувань на вісну втому, а втомна міцність аналізувалася шляхом побудови S−N-кривих та критичного спостереження поверхонь втомного руйнування досліджених зразків. Експериментальні результати показують, що механічні властивості та мікроструктурні особливості значно залежать від потужности зварювання. Втомна міцність зразків, зварених CO₂-лазером, зростає завдяки збільшенню глибини проникнення в зоні зварювання зі збільшенням потужности зварювання за обраних умов. Найкращі властивості спостерігалися у зразків, зварених за підведеної теплоти при 2500 Вт та швидкости зварювання у 100 см/хв.В данной работе исследована усталостная прочность нержавеющих сталей AISI 430—304, сваренных лучом CO₂-лазера. Эксперименты по лазерной сварке выполнялись в атмосфере гелия при мощностях сварки 2000, 2250 и 2500 Вт и скорости сварки 100 см/мин. Зоны сварки исследовались методами оптической микроскопии, сканирующей электронной микроскопии и энергодисперсионной спектроскопии. Испытания на усталость производились с использованием машины для испытаний на осевую усталость, а усталостная прочность анализировалась путём построения S−N-кривых и критического наблюдения поверхностей усталостного разрушения исследованных образцов. Экспериментальные результаты показывают, что механические свойства и микроструктурные особенности значительно зависят от мощности сварки. Усталостная прочность образцов, сваренных CO₂-лазером, возрастает благодаря увеличению глубины проникновения в зоне сварки с увеличением мощности сварки при выбранных условиях. Наилучшие свойства наблюдались у образцов, сваренных при подводимой теплоте с 2500 Вт и скорости сварки 100 см/мин