1,451 research outputs found
Variation in the ionic composition in convective showers in Pune, India
Rain water samples of equal volume (100 ml) were collected sequentially from 5 convective shower events for a period of 2 years during the summer monsoon seasons of 1988 and 1989 at Pune. A marked decrease in the concentrations of soil-oriented elements Na+, K+, Ca2+ and Mg2+ was observed in the first few samples in all the events followed by a decrease in pH of the subsequent samples. Surprisingly, SO42- also showed similar variation, indicating that soil is contributing some SO42- in rain water. Washout process appears to be an important mechanism for the removal of the major ions from the atmosphere. However, rainout processes seem to be important for the removal of NO3- ions. The study points out that sequential sampling during a single shower appears to give better information about the relationship among H+, Na+, K+, Ca2+, Mg2+, SO42- and NO3- as compared to bulk sampling for longer duration
Chloride and sodium ion increases in rain from salt seeded clouds
Chloride and sodium ion concentrations in rainwater from warm clouds seeded with a salt soapstone mixture were two to three times greater than in rain from non-seeded clouds east of Poona, India, during the 1974 summer monsoon. The warm cloud seeding experiment, begun in 1973 and studied intensively in 1974, 1976, 1979 and 1980, involved two 1600 sq. km experimental areas, each having 40 raingauges and separated by an intervening buffer (Fig. 1). Crossover randomization was use
Chemical composition and size distribution of atmospheric aerosols over the Deccan Plateau, India.
Measurements on atmospheric total aerosol were made at Poona during the summer and winter seasons of 1978–79. An Andersen particle sampler Model 20–810, Mark II (Andersen 2000 Inc. U.S.A.) which samples atmospheric particles with diameters ranging between 0.4 and 10.0 μm was used for the measurement. The mass distribution of the total aerosol, and separately for the chloride, sodium, ammonium, sulphate and nitrate components were obtained. The mass distribution of the aerosols exhibited a bimodal distribution in the size ranges 0.4–0.6 μm and 5–6 μm. The chloride and sodium components exhibited by and large a unimodal distribution. The ammonium and sulphate components exhibited a bimodal distribution during the monsoon and a unimodal distribution during the winter. The nitrate component exhibited a bimodal distribution during the monsoon and winter. The molecular form of this component appears to be ammonium nitrate in the sub-micron range and sodium nitrate in the higher size range (1–10 μm)
Characteristics of aerosols at traffic junctions in Pune city
Vehicular emissions are one of the potential sources of air pollution in the urban regions. Pune, one of the rapidly growing cities of India, faces the severe threat from this problem. Observations of total suspended particulates and Aitken nuclei were conducted at 4 traffic junctions in Pune city during summer (May 2000) and winter (Jan-Feb. 2001). Concentrations of TSP crossed the CPCB limit, recommended for commercial zone, at all the traffic junctions and also the number density of Aitken nuclei was very high. However, aerosols were alkaline in nature, in spite of high concentrations of SO4 and NO3, mainly due to the neutralizing effect of Ca, NH4, Na, Mg and K
Rubber Impact on 3D Textile Composites
A low velocity impact study of aircraft tire rubber on 3D textile-reinforced composite plates was performed experimentally and numerically. In contrast to regular unidirectional composite laminates, no delaminations occur in such a 3D textile composite. Yarn decohesions, matrix cracks and yarn ruptures have been identified as the major damage mechanisms under impact load. An increase in the number of 3D warp yarns is proposed to improve the impact damage resistance. The characteristic of a rubber impact is the high amount of elastic energy stored in the impactor during impact, which was more than 90% of the initial kinetic energy. This large geometrical deformation of the rubber during impact leads to a less localised loading of the target structure and poses great challenges for the numerical modelling. A hyperelastic Mooney-Rivlin constitutive law was used in Abaqus/Explicit based on a step-by-step validation with static rubber compression tests and low velocity impact tests on aluminium plates. Simulation models of the textile weave were developed on the meso- and macro-scale. The final correlation between impact simulation results on 3D textile-reinforced composite plates and impact test data was promising, highlighting the potential of such numerical simulation tools
Optimization of Weather Model
Weather Research and Forecasting (WRF) is a primitive application of High Performance Computing (HPC). Research on WRF being able to utilize the computation efficacy. Today’s HPC has so much research going on. There are various parallel Programming Technologies used to achieve the speedup.The Stencil Computation is used by WRF model for regional grid computation and it’s a difficult to compute because it depends on their entire neighbor’s. In this paper propped method to achieve the stencil Computation for parallel approach like open MP then apply Vectorization flags O3 and then last Vectorization. Analysis of all the results to how its speedup and achieved Optimized code for Stencil Computation
Measuring V_ub and probing SUSY with double ratios of purely leptonic decays of B and D mesons
The experimental prospects for precise measurements of the leptonic decays
B_u -> tau nu / mu nu, B_s -> mu+ mu-, D -> mu nu and D_s -> mu nu / tau nu are
very promising. Double ratios involving four of these decays can be defined in
which the dependence on the values of the decay constants is essentially
eliminated, thus enabling complementary measurements of the CKM matrix element
V_ub with a small theoretical error. We quantify the experimental error in a
possible future measurement of |V_ub| using this approach, and show that it is
competitive with the anticipated precision from the conventional approaches.
Moreover, it is shown that such double ratios can be more effective than the
individual leptonic decays as a probe of the parameter space of supersymmetric
models. We emphasize that the double ratios have the advantage of using |V_ub|
as an input parameter (for which there is experimental information), while the
individual decays have an uncertainty from the decay constants (e.g. f_B_s),
and hence a reliance on theoretical techniques such as lattice QCD.Comment: 21 pages, 4 figure
Observation of Spontaneous Brillouin Cooling
While radiation-pressure cooling is well known, the Brillouin scattering of
light from sound is considered an acousto-optical amplification-only process.
It was suggested that cooling could be possible in multi-resonance Brillouin
systems when phonons experience lower damping than light. However, this regime
was not accessible in traditional Brillouin systems since backscattering
enforces high acoustical frequencies associated with high mechanical damping.
Recently, forward Brillouin scattering in microcavities has allowed access to
low-frequency acoustical modes where mechanical dissipation is lower than
optical dissipation, in accordance with the requirements for cooling. Here we
experimentally demonstrate cooling via such a forward Brillouin process in a
microresonator. We show two regimes of operation for the Brillouin process:
acoustical amplification as is traditional, but also for the first time, a
Brillouin cooling regime. Cooling is mediated by an optical pump, and scattered
light, that beat and electrostrictively attenuate the Brownian motion of the
mechanical mode.Comment: Supplementary material include
Uranium in the eastern margin of western Siberian plate, or how to overcome crisis of uranium
Теоретические построения [5], свидетельствующие о катагенно-осадочном, эксфильтрационном происхождении железных руд Западно-Сибирского бассейна являются дополнительным фактором принципиальной возможности глубинного происхождения не только радиоактивных металлов, но и ванадия, марганца, благородных металлов и железа. Theoretical constructions [5], which provide evidence of catagenic-aqueous, exfiltration origin of ores of Western Siberian basin, are an additional attribute of principal opportunity for deep seated origin of not only radioactive metals, but also of vanadium, manganese, noble metals and ferrum
Uptake and yield of HIV testing and counselling among children and adolescents in sub-Saharan Africa: a systematic review.
INTRODUCTION: In recent years children and adolescents have emerged as a priority for HIV prevention and care services. We conducted a systematic review to investigate the acceptability, yield and prevalence of HIV testing and counselling (HTC) strategies in children and adolescents (5 to 19 years) in sub-Saharan Africa. METHODS: An electronic search was conducted in MEDLINE, EMBASE, Global Health and conference abstract databases. Studies reporting on HTC acceptability, yield and prevalence and published between January 2004 and September 2014 were included. Pooled proportions for these three outcomes were estimated using a random effects model. A quality assessment was conducted on included studies. RESULTS AND DISCUSSION: A total of 16,380 potential citations were identified, of which 21 studies (23 entries) were included. Most studies were conducted in Kenya (n=5) and Uganda (n=5) and judged to provide moderate (n=15) to low quality (n=7) evidence, with data not disaggregated by age. Seven studies reported on provider-initiated testing and counselling (PITC), with the remainder reporting on family-centred (n=5), home-based (n=5), outreach (n=5) and school-linked HTC among primary schoolchildren (n=1). PITC among inpatients had the highest acceptability (86.3%; 95% confidence interval [CI]: 65.5 to 100%), yield (12.2%; 95% CI: 6.1 to 18.3%) and prevalence (15.4%; 95% CI: 5.0 to 25.7%). Family-centred HTC had lower acceptance compared to home-based HTC (51.7%; 95% CI: 10.4 to 92.9% vs. 84.9%; 95% CI: 74.4 to 95.4%) yet higher prevalence (8.4%; 95% CI: 3.4 to 13.5% vs. 3.0%; 95% CI: 1.0 to 4.9%). School-linked HTC showed poor acceptance and low prevalence. CONCLUSIONS: While PITC may have high test acceptability priority should be given to evaluating strategies beyond healthcare settings (e.g. home-based HTC among families) to identify individuals earlier in their disease progression. Data on linkage to care and cost-effectiveness of HTC strategies are needed to strengthen policies
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