227 research outputs found
Use of Satellites To Determine Optimum Locations For Solar Power Stations
Ground measurements of solar radiation are too sparse to determine important mesoscale differences that can be of major significance in solar power station locations. Cloud images in the visual spectrum from the SMS/GOES geostationary satellites are used to determine the hourly distribution of sunshine on a mesoscale in the continental United States excluding Alaska. Cloud coverage and density as a function of time of day and season are considered through the use of digital data processing techniques. Low density cirrus clouds are less detrimental to solar energy collection than other types; and clouds in the morning and evening are less detrimental than those during midday hours of maximum insolation.
The seasonal geographic distributions of sunshine are converted to Langleys of solar radiation received at the earth*s surface through the use of transform equations developed from long-term measurements of these two parameters at 18 widely distributed stations. The high correlation between measurements of sunshine and radiation makes this possible. The output product will be maps showing the geographic distribution of total solar radiation on the mesoscale which is received at the earth\u27s surface during each season
Postwar Planning III
The possibility of considerable economic readjustment as it affects the livestock industry must be considered in postwar planning. Since the veterinarian guards the health of the livestock population, he must meet the challenge for service demanded by livestock industry
Observing biogeochemical cycles at global scales with profiling floats and gliders: prospects for a global array
Chemical and biological sensor technologies have advanced rapidly in the past five years. Sensors that require low power and operate for multiple years are now available for oxygen, nitrate, and a variety of bio-optical properties that serve as proxies for important components of the carbon cycle (e.g., particulate organic carbon). These sensors have all been deployed successfully for long periods, in some cases more than three years, on platforms such as profiling floats or gliders. Technologies for pH, pCO2, and particulate inorganic carbon are maturing rapidly as well. These sensors could serve as the enabling technology for a global biogeochemical observing system that might operate on a scale comparable to the current Argo array. Here, we review the scientific motivation and the prospects for a global observing system for ocean biogeochemistry
Treatment with pyrophosphate inhibits uremic vascular calcification
Pyrophosphate, which may be deficient in advanced renal failure, is a potent inhibitor of vascular calcification. To explore its use as a potential therapeutic, we injected exogenous pyrophosphate subcutaneously or intraperitoneally in normal rats and found that their plasma pyrophosphate concentrations peaked within 15âmin. There was a single exponential decay with a half-life of 33âmin. The kinetics were indistinguishable between the two routes of administration or in anephric rats. The effect of daily intraperitoneal pyrophosphate injections on uremic vascular calcification was then tested in rats fed a high-phosphate diet containing adenine for 28 days to induce uremia. Although the incidence of aortic calcification varied and was not altered by pyrophosphate, the calcium content of calcified aortas was significantly reduced by 70%. Studies were repeated in uremic rats given calcitriol to produce more consistent aortic calcification and treated with sodium pyrophosphate delivered intraperitoneally in a larger volume of glucose-containing solution to prolong plasma pyrophosphate levels. This maneuver significantly reduced both the incidence and amount of calcification. Quantitative histomorphometry of bone samples after double-labeling with calcein indicated that there was no effect of pyrophosphate on the rates of bone formation or mineralization. Thus, exogenous pyrophosphate can inhibit uremic vascular calcification without producing adverse effects on bone
Beam-target helicity asymmetry for ÎłânââÏâp in the N*resonance region
We report the first beam-target double-polarization asymmetries in the Îł ĂŸ nĂ°pĂ â Ïâ ĂŸ pĂ°pĂ reaction
spanning the nucleon resonance region from invariant mass W Œ 1500 to 2300 MeV. Circularly polarized
photons and longitudinally polarized deuterons in solid hydrogen deuteride (HD) have been used with the
CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Lab. The exclusive final state has been
extracted using three very different analyses that show excellent agreement, and these have been used to
deduce the E polarization observable for an effective neutron target. These results have been incorporated
into new partial wave analyses and have led to significant revisions for several ÎłnN* resonance
photocouplings
Photoproduction of K+Kâ meson pairs on the proton
The exclusive reaction ÎłpâpK+Kâ was studied in the photon energy range 3.0â3.8ââGeV and momentum transfer range 0.6<ât<1.3ââGeV2. Data were collected with the CLAS detector at the Thomas Jefferson National Accelerator Facility. In this kinematic range the integrated luminosity was approximately 20ââpbâ1. The reaction was isolated by detecting the K+ and the proton in CLAS, and reconstructing the Kâ via the missing-mass technique. Moments of the dikaon decay angular distributions were extracted from the experimental data. Besides the dominant contribution of the Ï meson in the P wave, evidence for SâP interference was found. The differential production cross sections dÏ/dt for individual waves in the mass range of the Ï resonance were extracted and compared to predictions of a Regge-inspired model. This is the first time the t-dependent cross section of the S-wave contribution to the elastic K+Kâ photoproduction has been measured
Effects of intrauterine food restriction and long-term dietary supplementation with L-arginine on age-related changes in renal function and structure of rats
We have previously demonstrated that restricting intrauterine food by 50% in 3-mo-old rats produced lower nephron numbers and early-onset hypertension, the latter being normalized by L-arginine administration. in 18-mo-old rats, such restriction increased glomerulosclerosis. in this study, we expanded our investigation, evaluating functional, morphologic, and immunohistochemical parameters in intrauterine-food-restricted 18-mo-old rats, either receiving L-arginine (RA18) or not (R18). Age-matched, non-food-restricted controls were assigned to similar groups with L-arginine (CA18) and without (C18). After weaning, L-arginine was given daily for 17 mo. No functional or morphologic changes were observed in C IS rats. the R18 rats developed early-onset hypertension, which persisted throughout the observation period, as well its significant proteinuria from 12 mo on. in RA18 rats, L-arginine decreased both blood pressure levels and proteinuria, and glomerular diameter was si,significantly smaller than in R18 rats (115.63 +/- 2.2 versus 134.8 +/- 1.0 mu m, p < 0.05). However, in RA18 rats, glomerular filtration rate remained depressed. Although L-arginine prevented glomerulosclerosis (R18 = 14%, RA18 = 4%; p < 0.05), glomerular expression of fibronectin and desmin was still greater in RA18 rats than in controls. Our data show that, although L-arginine prevented hypertension and proteinuria, glomerular injury still occurred, suggesting that intrauterine food restriction may be one of the leading causes of impaired renal function in adult life.Universidade Federal de SĂŁo Paulo, Dept Physiol, EPM, Dept Physiol, BR-04023900 SĂŁo Paulo, BrazilUniversidade Federal de SĂŁo Paulo, Dept Physiol, EPM, Dept Morphol,Embrol Div, BR-04023900 SĂŁo Paulo, BrazilUniv SĂŁo Paulo, Ribeirao Preto Sch Med, Dept Physiol & Biophys, Brookline, MA 02146 USAUniversidade Federal de SĂŁo Paulo, Dept Physiol, EPM, Dept Physiol, BR-04023900 SĂŁo Paulo, BrazilUniversidade Federal de SĂŁo Paulo, Dept Physiol, EPM, Dept Morphol,Embrol Div, BR-04023900 SĂŁo Paulo, BrazilWeb of Scienc
Connective tissue growth factor(CCN2), a pathogenic factor in diabetic nephropathy. What does it do? How does it do it?
Connective tissue growth factor (CTGF/CCN2) is a member of the CCN family of matricellular proteins. Its expression is induced by a number of factors including TGF-ÎČ. It has been associated with fibrosis in various tissues including the kidney. Diabetic nephropathy (DN) develops in about 30% of patients with diabetes and is characterized by thickening of renal basement membranes, fibrosis in the glomerulus (glomerulosclerosis), tubular atrophy and interstitial fibrosis, all of which compromise kidney function. This review examines changes in CTGF expression in the kidney in DN, the effects they have on glomerular mesangial and podocyte cells and the tubulointerstitium, and how these contribute to driving fibrotic changes in the disease. CTGF can bind to several other growth factors modifying their function. CTGF is also able to interact with receptors on cells, including integrins, tyrosine receptor kinase A (TrkA), low density lipoprotein receptor-related protein (LRP) and heparan sulphate proteoglycans. These interactions, the intracellular signalling pathways they activate, and the cellular responses evoked are reviewed. CTGF also induces the expression of chemokines which themselves have pharmacological actions on cells. CTGF may prompt some responses by acting through several different mechanisms, possibly simultaneously. For example, CTGF is often described as an effector of TGF-ÎČ. It can promote TGF-ÎČ signalling by binding directly to the growth factor, promoting its interaction with the TGF-ÎČ receptor; by triggering intracellular signalling on binding the TrkA receptor, which leads to the transcriptional repression of Smad7, an inhibitor of the TGF-ÎČ signalling pathway; and by binding to BMP-7 whose own signalling pathway opposing TGF-ÎČ is inhibited, leading to enhanced TGF-ÎČ signalling
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