19,034 research outputs found
Survey and Service on STD/HIV/AIDS in Namungo Mines,Lindi Region
Namungo is small-scale mining in Ruangwa district, Lindi Region, with deposits of green gemstone (tsavorite). About 400 men and women are living in temporary settlements. In August 2001, an STD/HIV/AIDS workplace intervention started which comprised of: A baseline KAP study with villagers and miners, A survey on infection rates with Syphilis and HIV, Treatment of patients with STD, An educational campaign and Development of plans for continuos collaboration between the mine and the health system. The KAP-study showed that 81% of respondents knew that sexual intercourse/sex without a condom is the main mode of HIV transmission. 80% correctly started that a person infected with HIV can remain a symptomatic for a long period. Half of them responded to had paid sex with more than one partner during the last 12 mouth. Those reporting having used a condom in the past 3 month were 48%. 92% of the respondents reported willingness for Voluntary Counseling and Testing (VCT) to know their HIV status. From 429 people who had came with symptoms of STDs most were treated for discharge syndrome (40% males,24 females) and for genital ulcers (38% in males and females) Testing and counseling for syphilis and HIV was offered to STD clients and volunteers. Infection rates were high in both groups, STD patients and volunteers with 18% for syphilis and 17% for HIV. The highest prevalence with 38% was found in women 30-34 years of age. The high infection rates, risky behavior and a high mobility of the people involved are a challenge to claim holders, health authorities and communities in the vicinity. Regular interventions urgently needed
Quantum transport in weakly coupled superlattices at low temperature
We report on the study of the electrical current flowing in weakly coupled
superlattice (SL) structures under an applied electric field at very low
temperature, i.e. in the tunneling regime. This low temperature transport is
characterized by an extremely low tunneling probability between adjacent wells.
Experimentally, I(V) curves at low temperature display a striking feature, i.e
a plateau or null differential conductance. A theoretical model based on the
evaluation of scattering rates is developed in order to understand this
behaviour, exploring the different scattering mechanisms in AlGaAs alloys. The
dominant interaction in usual experimental conditions such as ours is found to
be the electron-ionized donors scattering. The existence of the plateau in the
I(V) characteristics is physically explained by a competition between the
electric field localization of the Wannier-Stark electron states in the weakly
coupled quantum wells and the electric field assisted tunneling between
adjacent wells. The influence of the doping concentration and profile as well
as the presence of impurities inside the barrier are discussed
Quantification of efficiency improvements from integration of battery energy storage systems and renewable energy sources into domestic distribution networks
Due to the increasing use of renewable, non-controllable energy generation systems energy storage systems (ESS) are seen as a necessary part of future power delivery systems. ESS have gained research interest and practical implementation over the past decade and this is expected to continue into the future. This is due to the economic and operational benefits for both network operators and customers, battery energy storage system (BESS) is used as the main focus of this research paper. This paper presents an analytical study of the benefits of deploying distributed BESS in an electrical distribution network (DN). The work explores the optimum location of installing BESS and its impact on the DN performance and possible future investment. This study provides a comparison between bulk energy storage installed at three different locations; medium voltage (MV) side and low voltage (LV) side of the distribution transformer (DT) and distributed energy storage at customers’ feeders. The performance of a typical UK DN is examined under different penetration levels of wind energy generation units and BESS. The results show that the minimum storage size is obtained when BESS is installed next to the DT. However, the power loss is reduced to its minimum when BESS and wind energy are both distributed at load busbars. The study demonstrates that BESS installation has improved the loss of life factor of the distribution transformer
14-Bromo-12-chloro-2,16-dioxapentacyclohenicosa-3(8),10,12,14-tetraene-7,20-dione
In the title compound, C19H16BrClO4, both the fused xanthene rings and one of the cyclohexane rings adopt envelope conformations, while the other cyclohexane ring is in a chair conformation. In the crystal, molecules are linked by C-H...O hydrogen bonds, forming infinite chains running along [10-1] incorporating R22(16) ring motifs. In addition, C-H...[pi] interactions and weak [pi]-[pi] stacking interactions [centroid-centroid distance = 3.768 (3) Ã…] help to consolidate the packing
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