Direct Radiative Forcing by Smoke from Biomass Burning     

PV Hobbs  JS Reid  RA Kotchenruther  RJ Ferek  R Weiss 《Science (New York, N.Y.)》1997,275(5307):1776-1778

Airborne measurements in smoke from biomass burning in Brazil have yielded optical parameters that permit an improved assessment of the effects of smoke on Earth's radiation balance. The global-mean direct radiative forcing due to smoke from biomass burning worldwide is estimated to be no more than about -0.3 watt per square meter (cooling), compared with +2.45 watts per square meter (warming) due to anthropogenic greenhouse gases. On regional scales, direct radiative forcing due to smoke can be large and might indirectly affect global climate.  相似文献   

Earth-Based Radio Tracking of the Galileo Probe for Jupiter Wind Estimation     

WM Folkner  RA Preston  JS Border  J Navarro  WE Wilson  M Oestreich 《Science (New York, N.Y.)》1997,275(5300):644-646

Although the Galileo probe was designed to communicate only to the orbiter, the probe radio signal was detected at two Earth-based radio observatories where the signal was a billion times weaker. The measured signal frequency was used to derive a vertical profile of the jovian zonal wind speed. Due to the mission geometry, the Earth-based wind estimates are less sensitive to descent trajectory errors than estimates based on probe-orbiter Doppler measurements. The two estimates of wind profiles agree qualitatively; both show high wind speeds at all depths sampled.  相似文献   

猪舍内气流变化的模拟研究   总被引：6，自引：0，他引：6  

佟国红  张国强  MORSING S  STROM JS  RAVN P 《沈阳农业大学学报》2007,38(3):379-382

圈养动物舍内的气流变化对于室内的污染物扩散起到非常关键的作用,采用基于有限容积方法的计算流体动力学(CFD)软件对建于奥胡斯大学农业工程研究所空气物理实验室中的1:12.5猪舍模型内的气流进行了稳态和三维模拟。将模拟的气流速度与室内一个参考点的实际测试速度进行了对比,同时分析了气流入口不同紊流动能及扩散率取值对室内测试参考点气流速度模拟值的影响。结果表明,模拟值与测试值的相对误差在0.4%～11.4%之间。  相似文献   

Limnological perspectives on conservation of floodplain lakes in the Amazon basin     

John M. Melack  Daniele Kasper  João H.F. Amaral  Pedro M. Barbosa  Bruce R. Forsberg 《水产资源保护:海洋与淡水生态系统》2021,31(12):1041-1055

1. Limnological aspects of Amazon floodplain lakes are examined in the context of aquatic conservation.
2. A prerequisite to detecting and evaluating changes that could threaten the ecological health and organisms in floodplain lakes is understanding variation under present conditions. Based on one of the few studies with regular measurements over 2 years, chlorophyll, total phosphorus, dissolved oxygen, transparency, and total suspended solids in Lake Janauacá indicate that the lake is naturally quite variable with a mesotrophic to eutrophic status.
3. Direct threats to ecological health of floodplain lakes include mining operations that can increase turbidity and trace metals and reduce nutritional quality of sediments. Mercury contamination and methylation leads to bioaccumulation in aquatic organisms.
4. Deforestation in uplands increases nitrogen and phosphorus inputs to floodplain lakes and can alter trophic status. Deforestation in floodable forests alters the habitat and food of the fish that inhabit these forests.
5. Cumulative limnological responses as catchments are altered by urban, agricultural, and industrial developments, and as inundation is altered by changes in climate and construction of dams, have major implications for the ecology of floodplain lakes.
6. To improve understanding and management of threats to the conservation of aquatic Amazon biota and ecosystems requires considerably expanded and coordinated research and community-based management that includes the spectrum of floodplain lakes throughout the basin.

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Tail docking in dogs: A sample of attitudes of veterinarians and dog breeders in Queensland     

GJ NOONAN  JS RAND  JK BLACKSHAW †  J. PRIEST ‡ 《Australian veterinary journal》1996,73(3):86-88

One hundred veterinarians and 100 breeders of traditionally docked dogs from Queensland were surveyed by telephone to determine their attitudes towards tail docking. Eighty-four percent of the breeders surveyed were in favour of docking, whereas 83% of veterinarians were opposed to the practice. Most pups were docked between 1 and 3 days of age. All veterinarians surgically amputated the tail, whereas 16% of breeders applied rubber bands to the tail. Seventy-six percent of the veterinarians, but only 18% of the breeders believed that docking caused significant to severe pain. No veterinarians, but 25% of the dog breeders believed that docking was painless. Although recent changes to the Queensland Canine Control Council's rulings allow dogs with intact tails to be shown in traditionally docked classes, the requirement of breed standard was cited as the major reason for tail docking by both breeders and veterinarians.  相似文献   

OBSERVER VARIATION IN THE TWO-DIMENSIONAL ECHOCARDIOGRAPHIC EVALUATION OF MITRAL VALVE PROLAPSE IN DOGS     

Henrik D.  Pedersen  DVM  Kasper A.  Lorentzen  BMSci  BentØ  Kristensen  MD  DMSci 《Veterinary radiology & ultrasound》1996,37(5):367-372

In this study, the observer variation and the influence of observer experience in diagnosing mitral valve prolapse in dogs was assessed by having three observers with different degrees of echocardiographic experience (10 years, 4 years, and no prior experience) analyze 303 mitral valve video recordings from 253 dogs, both with and without mitral regurgitation. To assess intraobserver variation, 16 recordings were analyzed twice, and 34 dogs were scanned twice at intervals of a few days. By consensus, 90 dogs had no mitral valve prolapse, 130 had mild and 33 had severe mitral valve prolapse. Intraobserver repeatabilities ranged from 88% to 100% and interobserver repeatabilities from 70% to 78%. In 79% to 94% of the dogs that were scanned twice, the observers diagnosed both recordings identically. All repeatabilities were reduced by approximately 10% when mitral valve prolapse was graded into mild and severe. The three observers differed significantly in diagnosing mitral valve prolapse when compared with each other in pairs (all p-values < 0.01). The unexperienced observer had the highest and most unsystematic occurrence of false diagnoses. It is possible that the interobserver repeatabilities would have been lower had each sonographer obtained his own echocardiograms. We conclude, that mitral valve prolapse in dogs can be diagnosed using two-dimensional echocardiography with the same degree of observer variation as reported in human studies, and that education and training of staff is mandatory to ensure proper ultrasonographic evaluation.  相似文献   

Differences in Iron, Manganese, and Phosphorus Binding in Freshwater Sediment Vegetated with Littorella Uniflora and Benthic Microalgae     

Kasper Kjellberg Christensen 《Water, air, and soil pollution》1997,99(1-4):265-273

Undisturbed sediment cores from an oligotrophic lake were percolated with artificial porewater to examine the effects of isoetid macrophytes,Littorella uniflora, and benthic microalgae on daily dynamics of sediment retention of phosphorus (P) by either iron (Fe) or manganese (Mn). Retention of Fe and Mn was observed due to oxidation processes mediated by oxygen release fromL. uniflora roots and benthic microalgae. Therefore increased retention of P was observed because of P precipitation with oxidized Fe- and Mn-compounds. During light periods, the ratio between Fe and P precipitation in the sediment was positively correlated with the P uptake byL. uniflora (p < 0.001, r² = 0.984). The atomic precipitation ratio between Fe and P was between I and 2. The ratio between oxidized Fe-compounds and Fe-bound phosphate in the sediment was positively correlated with the root density ofL. uniflora (p < 0 001. r² = 0.995). The ratio between Mn and P precipitation was higher (26) than the ratio between Fe and P. The role of benthic primary producers on P retention in freshwater littoral sediments is discussed.  相似文献   

Ultraviolet effects in horse solaria?     

G Keck  I Kasper  G Schauberger  A Cabaj 《Berliner und Münchener tier?rztliche Wochenschrift》1988,101(2):49-52

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Efficacy and safety of ivermectin applied topically to cattle under field conditions in Australia     

JS EAGLESON  OR ALLERTON 《Australian veterinary journal》1992,69(6):133-134

Fifteen controlled field trials were conducted to evaluate the efficacy against gastrointestinal nematodes and safety of ivermectin when applied topically to cattle in Australia. Three hundred and fifty-one cattle received ivermectin, and 88 were untreated controls. The trials were conducted in 3 States and included a variety of cattle breeds and environmental conditions. Faecal samples were collected before treatment and 11 to 14 days after treatment for nematode egg counts. Data from these trials show that under Australian conditions, ivermectin applied along the mid line of the back from the withers to the sacral region at a dose rate of 500 mcg/kg body weight, effectively controlled gastrointestinal nematode infections, and did not produce unacceptable adverse reactions in the animals.  相似文献   

The efficacy of ivermectin topically applied to cattle for control of adult buffalo flies (Haematobia irritans exigua)     

A. MACQUEEN  RS TOZER  JS EAGLESON 《Australian veterinary journal》1993,70(5):195-196

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