Quantification of pore structure and gas diffusion as a function of scale   总被引：1，自引：0，他引：1  

H.-J. Vogel    I. Cousin  & K. Roth 《European Journal of Soil Science》2002,53(3):465-473

The quantification of the spatial heterogeneity of soil structure is one of the main difficulties to overcome for an adequate understanding of soil processes. There are different competing concepts for the type of heterogeneity, including macroscopic homogeneity, discrete hierarchy or fractal. With respect to these different concepts we investigate the structure of the pore space in one single sample (4 × 10³ mm³) by analysing basic geometric quantities of the pores > 0.3 mm within gradually increasing subsamples. To demonstrate the relation between geometrical and functional properties we simulate gas diffusion within the three‐dimensional pore space of the different subsamples. An efficient tool to determine the geometric quantities is presented. As a result, no representative elementary volume (REV) is found in terms of pore‐volume density which increases with sample size. The same is true for the simulated gas diffusion coefficient. This effect is explained by two different types of pores, i.e. big root channels and smaller pores, having different levels of organization. We discuss the different concepts of structural organization which may be appropriate models for the structure investigated. We argue that the discrete hierarchical approach is the most profitable in practice.  相似文献   

Mesenteric and omental sclerosis associated with metastases from gastrointestinal neoplasia in the dog     

L. Roth  J. M. King† 《The Journal of small animal practice》1990,31(1):27-30

Eleven cases of adenocarcinomas of the gastrointestinal tract were reviewed. Six tumours were considered to be of gastric origin, three originated from the jejunum and two from exocrine pancreatic tissue. Clinical signs were variable, but intermittent anorexia and vomiting were common features. Grossly, there was marked fibrosis involving the mesentery in nine cases, the omentum in 10 cases, and the abdominal surface of the diaphragm in three cases. Neoplasms that primarily involved the stomach or jejunum caused localised thickening of the bowel wall with mucosal ulceration. Pancreatic masses were continuous with the peritoneal lesion. The major histological feature in the mesentery and omentum was small islands of neoplastic cells surrounded by abundant proliferating connective tissue.  相似文献   

Relationship between corneal radius of curvature and age in rabbits     

N Roth 《The British veterinary journal》1969,125(11):560-563

  相似文献   

Pathologic changes in otitis externa     

L Roth 《Veterinary Clinics of North America: Small Animal Practice》1988,18(4):755-764

Otitic lesions must be evaluated in the context of the whole animal. Accurate historical and clinical assessments are important aids to the pathologist attempting to reach an accurate diagnosis. Primary lesions of the pinna, with or without involvement of the external ear canal, may be an extension of a more generalized dermatologic problem or may specifically involve the ear because of its unique gross and histologic characteristics.  相似文献   

Clinical trial of benzaldehyde in pets with solid tumors: preliminary study     

R L Grier  D F Merkley  J A Roth  M A Mouw 《American journal of veterinary research》1982,43(12):2270-2271

  相似文献   

Alteration of neutrophil function associated with coccidiosis in cattle: influence of decoquinate and dexamethasone     

J A Roth  J A Jarvinen  D E Frank  J E Fox 《American journal of veterinary research》1989,50(8):1250-1253

Twenty Holstein steers subclinically infected with coccidia were allotted to 2 groups of 10 steers each. One group received a diet containing 0.5 mg of decoquinate/kg of body weight. After 25 days on the diet, there was no difference between the groups in lymphocyte blastogenic responsiveness to mitogens; however, there were differences in neutrophil function. Lymphocytes from steers of the decoquinate-fed group had decreased random migration under agarose, enhanced cytochrome C reduction, and enhanced iodination activity. Other measures of neutrophil function evaluated (chemotactic index, Staphylococcus aureus ingestion, and antibody-dependent and -independent cell-mediated cytotoxicity) were not affected. After 30 days of decoquinate feeding, half of the cattle in each group received 5 daily IM injections of dexamethasone (0.04 mg/kg of body weight). The dexamethasone-treated steers from the group that did not have decoquinate in the diet developed clinical coccidiosis, whereas the decoquinate-treated steers remained clinically normal. Lymphocyte and neutrophil function were again evaluated for a 3-day period beginning 4 days after dexamethasone treatment was halted. Neutrophils from the steers that developed clinical coccidiosis after dexamethasone administration had significantly (P less than 0.05) inhibited random migration under agarose, cytochrome C reduction, and iodination activity, but significantly (P less than 0.01) enhanced S aureus ingestion. The feeding of decoquinate prevented the inhibition of neutrophil cytochrome C reduction and lessened the inhibition of neutrophil iodination in the dexamethasone-treated group. Dexamethasone treatment was associated with an inhibition of lymphocyte blastogenic responsiveness to phytohemagglutinin in principals as well as controls.  相似文献   

Angewandte un topographische Anatomie der Haustiere          下载免费PDF全文

Laszlo De Roth 《The Canadian veterinary journal. La revue veterinaire canadienne》1976,17(5):135

  相似文献   

Scintigraphic diagnosis of primary hepatocellular carcinoma in the woodchuck (Marmota monax)     

F A Kallfelz  W E Hornbuckle  H J Harvey  R J Wallace  L G Potkewitz  L Roth  B C Tennant 《American journal of veterinary research》1986,47(3):573-576

Hepatic imaging with 99mTc-sulfur colloid was used to diagnose primary hepatocellular carcinoma (PHC) in woodchucks infected with woodchuck hepatitis virus (WHV). Based on imaging results, 6 of 12 WHV-infected woodchucks had space-occupying hepatic lesions, and all 6 had PHC. Of the remaining woodchucks, 2 did not have PHC, 2 had discrete tumors (less than 1 cm diameter), 1 had miliary small tumors, and 1 had tumors located near the great vessels. Hepatic imaging was a valuable technique for diagnosis of PHC in WHV-infected woodchucks.  相似文献   

Effect of levamisole on lymphocyte blastogenesis and neutrophil function in dexamethasone-treated cattle   总被引：2，自引：0，他引：2  

J A Roth  M L Kaeberle 《American journal of veterinary research》1984,45(9):1781-1784

Levamisole was evaluated at 6 dose levels for its ability to prevent the dexamethasone-induced suppression of in vitro lymphocyte blastogenesis or neutrophil function in cattle. Dexamethasone (0.4 mg/kg of body weight, IM) and levamisole hydrochloride (0.5, 1.0, 2.0, 4.0, or 8.0 mg/kg orally) were administered to groups of 4 cattle daily for 3 days. Another group of 4 cattle were given the 3-day dexamethasone treatment and 6.0 mg/kg of levamisole (the recommended anthelmintic dose) was given only once on the 1st day that dexamethasone was given. Results obtained from the dexamethasone-levamisole-treated cattle were compared with results obtained from cattle that were given only dexamethasone. Levamisole had no apparent consistent ability to enhance lymphocyte blastogenic responsiveness (to the mitogens phytohemagglutinin, concanavalin A, or pokeweed mitogen or in a 1-way mixed lymphocyte reaction) or to enhance neutrophil function (random migration, nitroblue tetrazolium reduction, iodination, or antibody-dependent cell-mediated cytotoxicity) in dexamethasone-treated cattle.  相似文献   

Alterations in bovine lymphocyte function during the periparturient period   总被引：3，自引：0，他引：3  

M E Kehrli  B J Nonnecke  J A Roth 《American journal of veterinary research》1989,50(2):215-220

Lymphocytes from 8 Holstein heifers were evaluated during the periparturient period for mitogen-induced lymphocyte blastogenic responses. Phytohemagglutinin P- and concanavalin A-induced lymphocyte blastogenesis increased 2 and 3 weeks before parturition, respectively. However, by the first week after parturition, lymphocyte blastogenesis was markedly impaired.  相似文献