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1.
Binod Kumar BHATTARAF Berit KJELDSTAD Trond Morten THORSETH 《Canadian Metallurgical Quarterly》2011,28(4)
Nepal lies on the southern slope of Himalaya in Asia.In a width ranging between 150 and 250 km,the altitude varies greatly from about 100 m at its southern border to a maximum of 8848 min the northern part.Like the variation in altitude,climatic condition varies quite a lot.Long-term monthly mean erythemal UV daily dose values for Nepal are evaluated using Total Ozone Mapping Spectrometer (TOMS) estimation from the time of its overpass between 1996 and 2003.The results are presented as summer and winter maps of mean UV levels in each satellite grid.The mean winter erythemal UV daily dose ranges between 2.1 and 3.6 kJ m-2 whereas summer values are found to lie between 4.6 and 9.7 kJ m-2.The altitude variation increases the UV levels by about 0.2 kJ km-1 in winter months,and 0.9 kJ km-1 in summer.A multiyear monthly average erythemal daily dose in most of the areas shows that the summer value is about three times higher than that in winter.Although year-to-year variation is not pronounced in high- and mid-elevation regions,UV levels seemed to decrease from 1997 to 2002 in the southern part of the country in the low elevation region by about 5.35%.Due to the combined effects of the altitude,low ozone concentration in the troposphere,and thin air,surface UV radiation at higher altitudes is found to be higher than in the surrounding regions. 相似文献
2.
This work contains the results of the aerosol mass size distribution and preliminary studies on concentrations and size distribution of heavy metals (Pb, Zn, Cu, Mn, Fe and Cd) in indoor and outdoor environment in Upper Silesia (the highly industrialized region in the southern part of Poland). In studies, the measurements of aerosol concentration, mass size distribution, and evaluation of heavy metals concentration were made from December 1992 to April 1994 in some apartments in five towns in Upper Silesia and in one village in the Beskidy Mountains in both indoor and outdoor environments. The particles were fractionated in Andersen cascade impactor. The sampling time was 6-7 days and 4-5 days for indoor and outdoor respectively. Aerosol particulates were collected on A-type glass fiber collection substrate used later for determination of heavy concentrations by atomic absorption spectrophotometry (AAS 3, Carl Zeiss Jena). The dust was mineralized by the means of the mixture of hydrofluoric and nitric acids. The results of mass size distribution as well as the measurements of TSP for indoor and outdoor aerosol show that the main source of particulate matter indoors, in this region, are heavy polluted outdoor air and cigarette smoking. It can be said that, except homes in Knurów and Sosnowiec with hard smokers, the indoor levels of particulate pollution were significant lower than the outdoors levels. Whenever in the indoor environment appear additional source of particulate emission situation can changed. When we compare mass size distribution for outdoor aerosol and indoor aerosol contaminated by tobacco smoke, we can observed considerable increase of indoor aerosol level in the 0.33-0.54 microns size range. Besides, indoor aerosol status may be changed by coal stove emission (displacement of maximum peak to direction of coarse particles). The observed differences in concentration of particulate matter may also indicate the important differences in chemical and physical nature of particles caused by the air filtration and absorption during migration of ambient air into the indoor environment. On the base of comparison of the heavy metals concentrations of fine and coarse fraction and their indoor/outdoor ratio in five selected towns in Upper Silesia it can be said that the level of heavy metals in indoor aerosol is lower than in outdoor (except Pb and Cd) what suggest that migration of ambient air into the homes is a major process which give indoor air contamination of heavy metals.(ABSTRACT TRUNCATED AT 400 WORDS) 相似文献
3.
M Matsui H Tamura F Nagai H Homma A Miyawaki K Mikoshiba 《Canadian Metallurgical Quarterly》1998,109(1-3):69-80
Seasonal differences in the particle size fractions and mass loadings of household dust deposited on indoor surfaces were examined in four New Jersey homes. Housedust was collected during a 30-day period on non-electrostatic polyethylene sample plates on which a glass slide had been placed. In each home two samples were collected at a height of 1.5 m and two were collected at a height of 0.3 m above the floor. Dust samples were obtained from each home during a summer and winter collection period. Particle size measurement was completed using an adaptation of a Meridian ACAS 570 Interactive Laser Cytometer. Results indicated that the dust mass deposited on household surfaces during the summer was greater than during the winter. The arithmetic mean mass deposition rate for all houses was 0.37 +/- 0.13 microgram/cm2/day during the summer and 0.22 +/- 0.13 microgram/cm2/day during the winter. The total number of particles deposited, however, was greater during the winter than during the summer. The increase in winter time particle number was caused by greater numbers of particles with an equivalent spherical diameter < 2.5 microns. The most probable source of these particles was winter time combustion emissions within the residences and the subsequent particle deposition on household surfaces. The greater mass loadings measured on the low sampling plates during the summer were associated with a greater number of particles with an equivalent spherical diameter > 5 microns. In the winter, however, the particle mass and number loadings were similar at both heights. These results suggested that ventilation of the house during the summer allowed resuspended particles to enter which led to the higher levels of settled dust. Measurement of contaminant levels in housedust for exposure estimation therefore, should account for the seasonal and height differences in dust mass, and collect representative fractions of housedust that are available for human contact. Furthermore, since over 99% of the particles on indoor surfaces were < 50 microns any indirect sampling technique for dermal exposure estimation should have collection efficiencies similar to the hand of particles < 50 microns. 相似文献
4.
Satellite-Based Energy Balance for Mapping Evapotranspiration with Internalized Calibration (METRIC)—Applications 总被引:10,自引:0,他引:10
Richard G. Allen Masahiro Tasumi Anthony Morse Ricardo Trezza James L. Wright Wim Bastiaanssen William Kramber Ignacio Lorite Clarence W. Robison 《Canadian Metallurgical Quarterly》2007,133(4):395-406
Recent satellite image processing developments have provided the means to calculate evapotranspiration (ET) as a residual of the surface energy balance to produce ET “maps.” These ET maps (i.e., images) provide the means to quantify ET on a field by field basis in terms of both the rate and spatial distribution. The ET images show a progression of ET during the year or growing season as well as its spatial distribution. The mapping evapotranspiration at high resolution with internalized calibration (METRIC) is a satellite-based image-processing procedure for calculating ET. METRIC has been applied with high resolution Landsat images in southern Idaho, southern California, and New Mexico to quantify monthly and seasonal ET for water rights accounting, operation of ground water models, and determination of crop coefficient populations and mean curves for common crops. Comparisons between ET by METRIC, ET measured by lysimeter, and ET predicted using traditional methods have been made on a daily and monthly basis for a variety of crop types and land uses. Error in estimated growing season ET was 4% for irrigated meadow in the Bear River basin of Idaho and 1% for an irrigated sugar beet crop near Kimberly, Id. Standard deviation of error for time periods represented by each satellite image averaged about 13 to 20% in both applications. The results indicate that METRIC and similar methods such as SEBAL hold substantial promise as efficient, accurate, and inexpensive procedures to estimate actual evaporation fluxes from irrigated lands throughout growing seasons. 相似文献
5.
Regional Analysis of Nonmethane Volatile Organic Compounds in the Lower Troposphere of the Southeast United States 总被引:2,自引:0,他引:2
Nonmethane organic compounds (NMOCs) along with ozone as well as other trace gas and meteorological parameters were measured at eight rural sites located in the Southeast United States, as part of the Southern Oxidants Study. Fifty-four C2–C10 NMOCs were collected from 1,200–1,300 local time, once every six days from September 1992 through October 1993 and intermittently during 1994. This study was undertaken to characterize the nonmethane hydrocarbons in the rural areas of Southeast United States with respect to their concentrations, reactivities, and relative importance of natural and anthropogenic abundances of NMOCs. Though the sites are well removed from large urban source regions, the observations show a clear anthropogenic influence on the hydrocarbon levels at these rural sites. The data for the sites show similar seasonal patterns for total NMOC with summer maxima (average concentrations of 198 ppbC at the Long Creek, South Carolina, site to 47 ppbC at the Candor, North Carolina site) and fall minima (average concentrations of 73 ppbC at the Long Creek site to 31 ppbC at the Centreville, Alabama site). A secondary maximum is observed during the winter. A seasonal trend was observed in the concentrations of light molecular weight C2–C4 NMOCs (ethane, ethene, acetylene, propane, i-butane, and n-butane) with a winter maximum and a summer minimum. An analysis of changes in C2–C4 hydrocarbon ratios over a period of one year indicates that the variation is most likely due to seasonal changes in OH concentrations. A seasonal trend was also observed for the biogenically emitted NMOC, isoprene, with summer maxima (average concentrations of 37 ppbC at the Long Creek, South Carolina, site to 8.6 ppbC at the Giles County, Tennessee and Metter, Georgia, sites) and winter minima with winter seasonal values below the level of detection. Isoprene was observed to be the most dominant NMOC at most sites during the summer. The ambient concentrations of isoprene measured during the summer were found to be dependent on the ambient temperature. The monoterpenes a-pinene, b-pinene, and d-limonene also peaked during the summer with averages ranging between 3.19 ppbC (Centreville, Alabama) and 6.38 ppbC (Oak Grove, Missouri), and a background concentration of 1.25 to 1.9 ppbC for all the sites during the winter. 相似文献
6.
Afzal S. Siddiqui Chris Marnay Jennifer L. Edwards Ryan Firestone Srijay Ghosh Michael Stadler 《Canadian Metallurgical Quarterly》2005,131(1):2-25
This paper describes the economically optimal adoption and operation of distributed energy resources (DER) by a hypothetical California microgrid (μGrid) consisting of a group of commercial buildings over an historical test year, 1999. The optimization is conducted using a customer adoption model developed at Berkeley Lab and implemented in the General Algebraic Modeling System. A μGrid is a semiautonomous grouping of electricity and heat loads interconnected with the existing utility grid (macrogrid) but able to island from it. The μGrid minimizes the cost of meeting its energy requirements (consisting of both electricity and heat loads) by optimizing the installation and operation of DER technologies while purchasing residual energy from the local combined natural gas and electricity utility. The available DER technologies are small-scale generators (<500?kW), such as reciprocating engines, microturbines, and fuel cells, with or without combined heat and power (CHP) equipment, such as water and space heating and/or absorption cooling. By introducing a tax on carbon emissions, it is shown that if the μGrid is allowed to install CHP-enabled DER technologies, its carbon emissions are mitigated more than without CHP, demonstrating the potential benefits of small-scale CHP technology for climate change mitigation. Reciprocating engines with heat recovery and/or absorption cooling tend to be attractive technologies for the mild southern California climate, but the carbon mitigation tends to be modest compared to purchasing utility electricity because of the predominance of relatively clean central station generation in California. 相似文献
7.
Stratum corneum lipids play a predominant role in maintaining the water barrier of the skin. In order to understand the biological variation in the levels and composition of ceramides, ceramide 1 subtypes, cholesterol and fatty acids, stratum corneum lipids collected from tape strippings from three body sites (face, hand, leg) of female Caucasians of different age groups were analysed. In addition, we studied the influence of seasonal variation on the lipid composition of stratum corneum from the same body sites. The main lipid species were quantified using high-performance thin-layer chromatography and individual fatty acids using gas chromatography. Our findings demonstrated significantly decreased levels of all major lipid species, in particular ceramides, with increasing age. Similarly, the stratum corneum lipid levels of all the body sites examined were dramatically depleted in winter compared with spring and summer. The relative levels of ceramide 1 linoleate were also depleted in winter and in aged skin whereas ceramide 1 oleate levels increased. The other fatty acid levels remained fairly constant with both season and age, apart from lignoceric and heptadecanoic acid which showed a decrease in winter compared with summer. The decrease in the mass levels of intercellular lipids and the altered ratios of fatty acids esterified to ceramide 1, are likely to contribute to the increased susceptibility of aged skin to perturbation of barrier function and xerosis, particularly during the winter months. 相似文献
8.
Investigated adaptive changes in response to extinction by making provisions that permitted behavior to shift away from trained routine. The baiting of 4 arms in an 8-arm radial maze increasingly restricted movements by 32 male Sprague-Dawley rats to those arms: The unbaited arms afforded a new direction for behavior to take during extinction. Withdrawal of reward was followed by an immediate and active expansion of visited sites, and previously unrewarded arms were regularly sampled. This was one consequence of extinction; the other was the decline in overall rate of arm entry, whether arms were previously baited or not. Ethanol (1.5 or 2.0 g/kg) eliminated the spatial dispersions attendant on nonreward but did not affect the decline in overall responsiveness. It is concluded that ethanol's deletion of extinction-induced spatial variability may account for its impairment on reversal and other kinds of tasks that require a shift away from old patterns of behavior. (23 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
9.
Y Sugano 《Canadian Metallurgical Quarterly》1981,31(4):465-475
Heat production (M), dry heat loss (R+C), evaporative heat loss (E) and rectal temperature (Tre) were measured in a direct calorimeter in female mongrel dogs acclimatized to outdoor climate at Kanazawa (latitude; 36 degrees 35" N), Japan. M and total dry and evaporative heat losses (HL) were minimum at calorimeter wall temperatures (TW) of 26-29 degrees C in summer and 22-26 degrees C in winter (thermoneutral temperature; TNT). The seasonal shift of the lower critical temperature was confirmed. At TW below TNT, the values of M and HL were significantly higher in summer. At TW above TNT, these values increased. A TNT and above, M and HL were significantly higher in winter. (R+C) decreased linearly with increasing TW in both seasons. AT TW below 26 degrees C, (R+C) were significantly higher in summer. At TW above 26 degrees C, E increased greatly. The values of E were significantly higher in winter at TW 29-32 degrees C. Tre remained nearly constant at TNT and below, and increased at TW above TNT in both seasons. Mean body surface temperature (Tsf) decreased with decreasing TW. Body thermal conductance (K) was minimum at TW below 26 degrees C in summer and at TW below 22 degrees C in winter. At TW above these temperatures, K increased significantly. Whole body insulation (I) was significantly higher in winter, particularly at TW 18 degrees C. These results suggest that the dogs reared outdoors in winter acclimatized to cold in two ways; by increasing the insulating effect of the fur coat and by elevating resting heat production. 相似文献
10.
A key challenge in managing water quality and meeting compliance standards is accounting for both the anthropogenic and natural contributions of a range of water quality constituents. This study quantified levels of solids, metals, and nutrients in storm-water runoff from 18 sites across 11 watersheds representing a range of natural conditions in southern California. Constituent concentration and flux were measured over the course of a variety of storms in order to investigate temporal and spatial patterns in constituent levels, and to identify the most important environmental attributes affecting background water quality. Metals and nutrient concentrations from the natural catchments were typically one to two orders of magnitude lower than those from developed catchments. In contrast, total suspended solids levels were comparable to those found in urban storm water from Los Angeles. Geologic setting had the greatest effect on constituent levels at natural sites. Unlike urban systems, natural catchments do no appear to exhibit a first flush phenomenon, with a substantial portion of the constituent load occurring later in the storm. Ratios of particulate to dissolved metals concentrations changed considerably over the course of storms suggesting that bioavailability of constituents from natural areas may vary over storm duration. 相似文献
11.
The present study investigates the interdecadal variability of seasonal mean surface solar radiation over Northwest China using station observations from 1961-2003. Spring and summer surface solar radiation over Northwest China was lower in the late 1970s through 1990s than in the 1960s through the mid-1970s, and fall and winter surface solar radiation displayed similar patterns. These results indicate that the decrease in spring and summer surface solar radiation may be associated with increased low-cloud cover over Northwest China. Rainfall anomalies were closely related to the low-cloud cover over Northwest China and with the Northern Hemisphere circumglobal teleconnection in spring, summer, and winter. 相似文献
12.
Based on vital statistics from 1979 to 1983, we used a time-series analysis using the Box-Jenkins model (ARIMA model) to compare the seasonality of preterm births among 47 prefectures in Japan. We also evaluated the relation between seasonality of preterm births and temperature. According to the Box-Jenkins analysis, a seasonal moving average was detected for 44 prefectures. The seasonality of preterm births in general shows a bimodal pattern with two peaks, one in summer and one in winter. The most interesting result is that the peaks show a trend with geographic location; one peak is dominant in winter among the northern prefectures and the other peak is dominant in summer among the southern prefectures. Another important result is that the winter increase in preterm births is negatively correlated with mean winter temperature (R = -0.424, p = 0.003); on the contrary, the summer increase in preterm births is positively correlated with the average summer temperature (R = 0.549, p < 0.001). These results suggest that climate-associated factors should be associated with the occurrence of preterm births in Japan. 相似文献
13.
Surges in the size of adult populations of the flood-water mosquito Aedes albifasciatus can produce important economical losses because of the way this species irritates livestock. Although this species is also the main vector of west equine encephalitis in Argentina, little is known about the factors affecting its population dynamics, as it is difficult to obtain data on its abundance over a large area. However, the results of intensive study of the mosquito in a few sites might reasonably be extrapolated to a regional scale by the use of remotely sensed data. The adult, larval and pupal stages of Ae. albifasciatus were sampled at five field sites to the south of Mar Chiquita Lake, either once a month (during the dry, cold season) or once a fortnight (during the warm, rainy season), between August 1992 and April 1993. The measured abundance of adults or pre-adults and a meteorological coefficient useful for the estimation of larval abundance each showed significant correlation with various statistics derived from normalized-difference, vegetation indices (NDVI) calculated from satellite (NOAA-AVHRR) imagery. A linear discriminant analysis, using data on NDVI, rainfall and temperature, accurately identified periods with and without pre-adults. The satellite imagery was also useful in the estimation of larval abundance and consequently could be used to predict adult abundance 7 days in advance. Even though the satellite data employed have poor spatial resolution, their high temporal resolution makes them very useful in studies of the population dynamics of mosquitoes in general, at least once the relevant variables and their relationships with mosquito breeding and survival have been identified. 相似文献
14.
Sensitivity Analyses and Sensitivity Coefficients of Standardized Daily ASCE-Penman-Monteith Equation 总被引:4,自引:0,他引:4
Suat Irmak José O. Payero Derrel L. Martin Ayse Irmak Terry A. Howell 《Canadian Metallurgical Quarterly》2006,132(6):564-578
The sensitivity of the standardized ASCE grass-reference Penman-Monteith evapotranspiration (ASCE-PM ETo) equation to climate variables in different regions has not yet been studied. Sensitivity analyses for the standardized daily form of the ASCE-PM equation were conducted on wind speed at 2?m height (U2), maximum and minimum air temperatures (Tmax and Tmin), vapor pressure deficit (VPD), and solar radiation (Rs) in the following regions of the United States: semiarid (Scottsbluff, Nebraska, and Bushland, Texas), a Mediterranean-type climate (Santa Barbara, California), coastal humid (Fort Pierce, Florida), inland humid and semihumid (Rockport, Missouri, and Clay Center, Nebraska), and an island (Twitchell Island, California). The sensitivity coefficients were derived for each variable on a daily basis. In general, ETo was most sensitive to VPD at all locations, while sensitivity of ETo to the same variable showed significant variation from one location to another and at the same location within the year. After VPD, ETo was most sensitive to U2 in semiarid regions (Scottsbluff, Clay Center, and Bushland) during the summer months. The Rs was the dominant driving force of ETo at humid locations (Fort Pierce and Rockport) during the summer months. At Santa Barbara, the sensitivity of ETo to U2 was minimal during the summer months. At Bushland, Scottsbluff, and Twitchell Island, ETo was more sensitive to Tmax than Rs in summer months, whereas it was equally sensitive to Tmax and Rs at Clay Center. The ETo was not sensitive to Tmin at any of the locations. The change in ETo was linearly related to change in climate variables (with r2 ≥ 0.96 in most cases), with the exception of Tmin, at all sites. Increase in ETo with respect to increase in climate variable changed considerably by month. On an annual average, a 1°C increase in Tmax resulted in 0.11, 0.06, 0.16, 0.07, 0.11, 0.08, and 0.10?mm increases in ETo at Scottsbluff, Santa Barbara, Bushland, Fort Pierce, Twitchell Island, Rockport, and Clay Center. A 1?m?s?1 increase in U2 resulted in 0.42, 0.18, 0.37, 0.28, 0.31, 0.20, and 0.26?mm increases in ETo at the same locations. A unit increase in Tmax resulted in the largest increase in ETo at Bushland, and a unit increase in Rs caused the largest increases in ETo at Fort Pierce. A 1?MJ?m?2?d?1 increase in Rs resulted in 0.05, 0.08, 0.06, 0.11, 0.05, 0.06, and 0.06?mm increases in ETo at the same locations. A 0.4?kPa increase in VPD resulted in 1.13, 0.54, 1.29, 0.57, 1.04, 1.10, and 1.22?mm increases in ETo at the same locations. The U2 had the most effect on ETo at Scottsbluff and Bushland, the two locations where dry and strong winds are common during the growing season. The sensitivity coefficient for Rs was higher during the summer months and lower during the winter months, and the opposite was observed for VPD (except for Twitchell Island). The decrease of the sensitivity coefficients for Rs corresponding to an increase in the sensitivity coefficient for VPD is due to a decrease in the energy term in favor of the increase in significance of the aerodynamic term of the standardized ASCE-PM equation in summer versus winter months. Because the ASCE-PM and the Food and Agriculture Organization paper number 56 Penman-Monteith (FAO56-PM) equations are identical when applied on a daily time step, the results of the sensitivity analyses and sensitivity coefficients of this study should be directly applicable to the FAO56-PM equation. 相似文献
15.
Rick Jacqueline H.; Horvitz Jon C.; Balsam Peter D. 《Canadian Metallurgical Quarterly》2006,120(2):488
Dopamine (DA) neurons respond to unexpected food delivery and are inhibited during the omission of expected reward. DA receptor blockade mimics some, but not all, aspects of nonreward (extinction) conditions. It was therefore of interest to ask whether DA receptor blockade produces extinction-like increases in behavioral variability in addition to its well-known operant response-suppressing effects. In the current experiment, rats were trained drug-free on an operant task in which they pressed on a keyboard. Two of the keys led to food on a continuous reinforcement schedule. Both response rates and behavioral variability were measured. Test day administration of D? and D? antagonists SCH23390 and raclopride, like extinction, suppressed responding but, unlike extinction, did not lead to an increase in variability. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
16.
Evaluating Bioretention Hydrology and Nutrient Removal at Three Field Sites in North Carolina 总被引:6,自引:0,他引:6
W. F. Hunt A. R. Jarrett J. T. Smith L. J. Sharkey 《Canadian Metallurgical Quarterly》2006,132(6):600-608
Three bioretention field sites in North Carolina were examined for pollutant removal abilities and hydrologic performance. The cells varied by fill media type or drainage configuration. The field studies confirmed high annual total nitrogen mass removal rates at two conventionally drained bioretention cells (40% reduction each). Nitrate-nitrogen mass removal rates varied between 75 and 13%, and calculated annual mass removal of zinc, copper, and lead from one Greensboro cell were 98, 99, and 81%, respectively. All high mass removal rates were due to a substantial decrease in outflow volume. The ratio of volume of water leaving the bioretention cell versus that which entered the cell varied from 0.07 (summer) to 0.54 (winter). There was a significant (p<0.05) change in the ratio of outflow volume to inflow volume when comparing warm seasons to winter. Cells using a fill soil media with a lower phosphorus index (P-index), Chapel Hill cell C1 and Greensboro cell G1, had much higher phosphorus removal than Greensboro cell G2, which used a high P-index fill media. Fill media selection is critical for total phosphorus removal, as fill media with a low P-index and relatively high CEC appear to remove phosphorus much more readily. 相似文献
17.
OBJECTIVE: To evaluate the effect of seasonal variations in UV B-exposure on calcium absorption and bone turnover in young women with the overall goal to assess the potential benefit of a vitamin D supplementation during wintertime. DESIGN: Cross-sectional study. SETTING: Area of Bonn, Germany (51 degrees N). SUBJECTS: Thirty-eight women (24.5+/-0.5 y) studied in winter and 38 females of the same age (24.7+/-0.4 y) studied in summer. RESULTS: As estimated by a 4 d food record, both groups had similar dietary calcium and phosphorus intakes (> 1200 mg/d, respectively) covering actual recommendations. Significant reductions in serum concentrations of 25-hydroxyvitamin D (25OHD) and calcitriol, fractional calcium absorption (Fc220, measured by means of a stable strontium test), 24h urinary calcium and 24h urinary phosphorus excretion were observed during wintertime. 25OHD but not calcitriol was correlated with Fc220 values and with 24h urinary phosphorus excretion. Moreover, Fc220 was related to 24 h urinary calcium excretion. Fasting 2 h-urinary deoxypyridinoline concentrations (biomarker of bone resorption) and serum levels of carboxyterminal propeptide of type I procollagen (biomarker of bone formation) showed no differences between summer and winter. CONCLUSIONS: Our data indicate a decrease in intestinal calcium and phosphorus absorption during wintertime, most likely because of a reduction in serum 25OHD levels. Since bone turnover was not affected by the seasonal differences in mineral metabolism, there is no objective for young women with high calcium intake to supplement vitamin D during wintertime. 相似文献
18.
David W. Ostendorf Erich S. Hinlein David P. Ahlfeld Jason T. DeJong 《Canadian Metallurgical Quarterly》2006,132(12):1562-1571
Field data and existing theory suggest that pavement texture governs the seasonal persistence of deicing agent solids and the storm scale variability of the specific conductivity of highway runoff. We measured precipitation, runoff, and specific conductivity for 50 storms over four deicing seasons at a highway drainage system in southeastern Massachusetts. An average pavement texture of 2.44?mm was measured and 5.17×105?kg of calcium magnesium acetate, salt, and premix applications was reported as well. Catchments and a depression storage layer model the highway drainage system, which routes hyetographs and slowly dissolving deicing agent solids to storm scale hydrographs and specific conductivity pollutographs. We equate the average pavement texture to the depression storage layer depth, which receives applied deicing agent solids, controls their dissolution during a storm, and governs their seasonal scale persistence. The observed average pavement texture, precipitation, and deicing agent applications yield first flush (storm scale) specific conductivity values in the depression storage layer that range from a winter maximum of 15?mS/cm to summer values two orders of magnitude lower. The winter maximum, or seasonal scale first flush of specific conductivity, would be lower for rougher pavement due to slower dissolution. The rougher pavement would also induce stronger persistence of deicing agent solids throughout the year, so that appreciable storm scale first flushes would occur in the summer. 相似文献
19.
H Bisgaard 《Canadian Metallurgical Quarterly》1998,157(2):518-521
This article describes a new "automatic spacer" device, which has been developed to improve the delivery of inhaled medication to young children. In the device, a dry powder inhaler (DPI) is mechanically actuated into a nonelectrostatic spacer, producing an aerosol cloud of fine drug particles (aerodynamic diameter, < 4.7 microm) with a long half-life. The new device combines the principal advantages of the conventional spacer and the DPI. It has the potential to provide a high ratio between lung dose and pharyngeal dose, without need for coordination or forced inhalation, and it avoids exposure of the patient to the additives and propellants used in pressurized metered dose inhalers. Studies with the prototype device show a high yield of fine drug particles in the aerosol (mass median aerodynamic diameter, 2.8 microm), a high repeatability of drug delivery owing to the mechanical nature of the actuation (relative standard deviation, 12%), and a prolonged residence time of the fine particle aerosol (half-life of the fallout of the fine particles, 82 s). These features should prove advantageous in the treatment of young children with inhaled medication. 相似文献
20.
Carp (Cyprinus carpio L.) whole brain was used to investigate the thermal acclimation changes under normoxic conditions of three-subclasses (alkenylacyl-, alkylacyl- and diacyl-subclasses) of choline glycerophospholipids (CGP), ethanolamine glycerophospholipids (EGP) and inositol glycerophospholipids (IGP) as well as their acyl chain profiles and molecular species composition. The alkenylacyl subclass of CGP and IGP and the alkylacyl subclass of CGP and EGP varied significantly during summer (25 degrees C) acclimation compared to winter (5 degrees C). The levels of alkenylacyl and alkylacyl-CGP, alkylacyl-EGP and alkenylacyl-IGP were 17.3-, 3.7-, 3.5- and 1.3-fold higher in the summer, respectively, while the alkenylacyl EGP was moderately lower. The levels of diacyl subclasses from CGP and IGP were considerably lower in the summer to compensate for the higher proportion of alkenylacyl and alkylacyl subclasses. Significant changes of ether phospholipids and the reorganization of the molecular species composition of all lipid subclasses may be associated with the "fine tuning" of the physical properties of the cellular membranes in carp brain due to temperature acclimation. The overall acyl chain profile of the three subclasses of carp brain phospholipids showed differences in composition depending upon the subclass of the individual phospholipid. Generally the polyunsaturated fatty acid (PUFA) chain composition increased relative to monounsaturated fatty acid (MUFA) and saturated fatty acids (SFA) during winter acclimation. Docosahexaenoic acid (DHA) was richer in the winter compared to summer. However, no DHA was found in ether-containing species of IGP from either winter or summer, except for 2% in alkylacyl-IGP during the summer. The above observations suggest that the content of ether phospholipids (alkenylacyl and alkylacyl) as well as the reorganization of the molecular species composition of all phospholipids may serve to maintain a functional fluid-crystalline state to preserve the signaling functions in carp brain. 相似文献