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51.
Within different land‐use systems such as agriculture, forestry, and fallow, the different morphology and physiology of the plants, together with their specific management, lead to a system‐typical set of ecological conditions in the soil. The response of total, mobile, and easily available C and N fractions, microbial biomass, and enzyme activities involved in C and N cycling to different soil management was investigated in a sandy soil at a field study at Riesa, Northeastern Germany. The management systems included agricultural management (AM), succession fallow (SF), and forest management (FM). Samples of the mineral soil (0—5, 5—10, and 10—30 cm) were taken in spring 1999 and analyzed for their contents on organic C, total N, NH4+‐N and NO3—‐N, KCl‐extractable organic C and N fractions (Corg(KCl) and Norg(KCl)), microbial biomass C and N, and activities of β‐glucosidase and L‐asparaginase. With the exception of Norg(KCl), all investigated C and N pools showed a clear relationship to the land‐use system that was most pronounced in the 0—5 cm profile increment. SF resulted in greater contents of readily available C (Corg(KCl)), NH4+‐N, microbial biomass C and N, and enzyme activities in the uppermost 5 cm of the soil compared to all other systems studied. These differences were significant at P ≤ 0.05 to P ≤ 0.001. Comparably high Cmic:Corg ratios of 2.4 to 3.9 % in the SF plot imply a faster C and N turnover than in AM and FM plots. Forest management led to 1.5‐ to 2‐fold larger organic C contents compared to SF and AM plots, respectively. High organic C contents were coupled with low microbial biomass C (78 μg g—1) and N contents (10.7 μg g—1), extremely low Cmic : Corg ratios (0.2—0.6 %) and low β‐glucosidase (81 μg PN g—1 h—1) and L‐asparaginase (7.3 μg NH4‐N g—1 2 h—1) activities. These results indicate a severe inhibition of mineralization processes in soils under locust stands. Under agricultural management, chemical and biological parameters expressed medium values with exception for NO3—‐N contents which were significantly higher than in SF and FM plots (P ≤ 0.005) and increased with increasing soil depth. Nevertheless, the depth gradient found for all studied parameters was most pronounced in soils under SF. Microbial biomass C and N were correlated to β‐glucosidase and L‐asparaginase activity (r ≥ 0.63; P ≤ 0.001). Furthermore, microbial biomass and enzyme activities were related to the amounts of readily mineralizable organic C (i.e. Corg(KCl)) with r ≥ 0.41 (P ≤ 0.01), suggesting that (1) KCl‐extractable organic C compounds from field‐fresh prepared soils represent an important C source for soil microbial populations, and (2) that microbial biomass is an important source for enzymes in soil. The Norg(KCl) pool is not necessarily related to the size of microbial biomass C and N and enzyme activities in soil.<?show $6#> 相似文献
52.
Leaching of carbon and nitrogen from a sandy soil substrate: A comparison between suction plates and ion exchange resins
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To determine boundary effects on leaching, we investigated (1) how filter materials affect the concentrations of dissolved organic carbon (DOC) and nitrate (NO3‐N) in soil percolates and (2) whether ion exchange resins and suction plates are equally suited to capture NO3‐N. DOC leaching was higher with PE suction plates and plate material did not affect NO3‐N leachate concentrations. Cumulative NO3‐N leaching was similar for glass suction plates and ion exchange resins. 相似文献
53.
54.
Amara H. Estrada Herbert W. Maisenbacher III VMD Robert Prošek DVM MS Jesse Schold PhD Melanie Powell BS James M. VanGilder BS 《Journal of Veterinary Cardiology》2009,11(2):79-88
Objective
To compare left ventricular synchronization and systolic performance with transvenous pacing of the right ventricular apex (RVA), left ventricular free wall (LVF) or simultaneous pacing of the RVA and LVF (BiV).Animals, materials and methods
Seven canine patients with complete heart block. Prospective study evaluating effect of pacing site. Twenty four hours following implantation of transvenous BiV pacing systems, electrocardiograms and echocardiograms were assessed during pacing from the: (1) Right Atrial Appendage/RVA (RAA/RVA), (2) RAA/LVF, and (3) RAA/BiV.Results
QRS duration was significantly shorter with BiV pacing versus LVF pacing (p < 0.001), or RVA pacing (p < 0.001). Echocardiographic indices of systolic performance fractional shortening (FS), ejection fraction (EF), cardiac output (CO) were significantly higher with BiV pacing than with pacing from the RVA (P = 0.023, 0.006, and 0.002 respectively). Cardiac output, measured by the biplane Simpson's method, was higher with LVF versus RVA pacing (P = 0.036). There was no difference in FS or EF when comparing LVF to RVA pacing. Tissue Doppler measurements of synchronization and systolic performance did not show any difference between pacing mode, but a significantly increased number of segments were seen to contract following aortic valve closure during LVF pacing (P = 0.0268) and RVA pacing (P = 0.0197) as compared to BiV pacing.Conclusions
Findings suggest that BiV pacing improves cardiac output and systolic performance versus RVA pacing. This improvement however, is not reflected in tissue Doppler indices of synchronization and systolic performance. 相似文献55.
Nicole I. Stacy Mary B. Nabity Nicole Hackendahl Melanie Buote Jennifer Ward Pamela E. Ginn William Vernau William L. Clapp John W. Harvey 《Veterinary clinical pathology / American Society for Veterinary Clinical Pathology》2009,38(1):113-120
Abstract: Two young adult dogs with gastrointestinal signs were each found to have an intra‐abdominal mass based on physical examination and diagnostic imaging. On exploratory laparotomy, small intestinal masses and mesenteric lymphadenopathy were found in both dogs; a liver mass was also found in dog 1. Cytologic and histologic examination of intestinal and liver masses and mesenteric lymph nodes revealed 2 distinct lymphoid cell populations: lymphoblasts and atypical Mott cells. With Romanowsky stains, the atypical Mott cells contained many discrete, clear to pale blue cytoplasmic inclusions consistent with Russell bodies that were positive by immunohistochemistry for IgM and CD79a in both dogs and for IgG in dog 2. The Mott cells and occasional lymphoblasts stained strongly positive with periodic acid‐Schiff. Using flow cytometric immunophenotyping in dog 1, 60% of peripheral blood mononuclear cells and 85% of cells in an affected lymph node were positive for CD21, CD79a, IgM, and MCH II, indicative of B‐cells. With electron microscopy, disorganized and dilated endoplasmic reticulum was seen in Mott cells in tumors from both dogs. Antigen receptor gene rearrangement analysis of lymph node and intestinal masses indicated a clonal B‐cell population. Based on cell morphology, tissue involvement, and evidence for clonal B‐cell proliferation, we diagnosed neoplasms involving Mott cells. To the authors' knowledge, this is the second report of Mott cell tumors or, more appropriately, B‐cell lymphoma with Mott cell differentiation, in dogs. More complete characterization of this neoplasm requires further investigation of additional cases. This lymphoproliferative disease should be considered as a differential diagnosis for canine gastrointestinal tumors. 相似文献
56.
A major strategy in the creation of sustainable economies is the establishment of alternative market institutions, such as fair trade and local market systems. However, the dynamics of these alternative markets are poorly understood. What are the rules of behavior by which these markets function? How do these markets maintain their separate identity as “alternative”: apart from the conventional (“free”) market system? Building on Lyson’s notion of civic agriculture, we argue that alternative markets maintain themselves through civic engagement. However, we argue that the civically-engaged practices of alternative markets are poorly understood. We seek, therefore, to begin a conversation about the everyday forms of civic engagement in alternative practice and to do this we introduce a few useful conceptual tools. Building upon ideas in science studies about the collaboration of scientists (Hess, Alternative pathways in science and industry, 2007) we argue that civic markets have their own “market fields” and “modes of governance” (Bulkeley et al., Environment and Planning A 39:2733–2753, 2007), their own fields of social interaction in which rules of behavior become stabilized and determine how the market works. The creation of a social field also requires the demarcation of boundaries, referred to in the science studies literature as “boundary work” (Gieryn, Cultural boundaries of science: Credibility on the line, 1999). We apply the idea of boundary work to understand how alternative market actors maintain boundaries between alternative and conventional markets. Finally, studies of collaboration in science have often centered on the object created through these interactions, an object that is partially material and partially a product of knowledge, what (Rheinberger, Toward a history of epistemic things: Synthesizing proteins in the test tube, 1997) calls an “epistemic object.” We use this idea to understand that the creation of alternative objects of exchange, such as organic food, are epistemic objects in that they combine both particular materialities and particular ways of knowing. Using these concepts, we will carry out a close analysis of the mode of governance in the national organic market, looking specifically a recent governance crisis in organic agriculture known as the Harvey lawsuit. 相似文献
57.
Melanie E. Hauber David Bierbach Karl Eduard Linsenmair 《Journal Of Applied Aquaculture》2013,25(1):67-84
The traditional whedo system involves the digging of large ditch-like ponds that fill seasonally with flood water, trapping fish which are subsequently harvested during the dry season. Although whedos are well described in the South of Benin, basic information necessary for their management in the North is lacking. Since 1998, the commune of Malanville has experienced a kind of ‘blue revolution’ because up to now, approximately 500 whedos (known locally as tschifi dais) have been constructed covering a total surface area of 9.3 ha, thus reflecting the high acceptance of the practice among the local population. Despite the fast development this system has received little attention from national development planners and international agencies, but in view of the disastrous state of the river Niger's fishery, sustainable aquaculture, fully relying on local species should be supported to release pressure on natural fish stocks. Instead of focussing all efforts on the introduction of modern aquaculture, it is important to enhance the existing system because of the knowledge and acceptance by the local population. This paper characterizes the current management and the technical as well as economical features of the tschifi dais in the commune of Malanville, northern Benin. 相似文献
58.
Murat O. Balaban Melanie Chombeau Bahar Gümüş Dilşat Cirban 《Journal Of Aquatic Food Product Technology》2013,22(1):45-52
The objective of this study was to develop two methods to predict the volume of whole Alaska pollock and to compare the results with the experimentally measured volumes. One hundred fifty-five whole pollock, obtained from a Kodiak processor, were individually immersed in a graduated cylinder equipped with an outflow tube to catch the displaced water as a result of immersion. The weight of the water was recorded. Then the fish were placed in a light box equipped with a digital video camera, and the side view and top view recorded (2 images for each fish). A reference square of known surface area was placed by the fish. A cubic spline method to predict volume by integration of cross-sectional area slices based on the top and side views and an empirical equation using dimensional (length L, width W, depth D) measurements at three locations of the fish image were developed. The R2 value for the correlation between the L × W × D versus measured volume was 0.987. The best R2 for the correlation of the predicted volume by the cubic spline method versus the measured volume was 0.99. Image analysis can be used reliably to predict the volume of whole Alaska pollock. 相似文献
59.
Concurrent multiple myeloma and mast cell neoplasia in a 13‐year‐old castrated male Maine Coon cat
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Jonathan M. Bagwell Heather R. Herd Melanie A. Breshears Steven Hodges Theresa E. Rizzi 《Veterinary clinical pathology / American Society for Veterinary Clinical Pathology》2017,46(1):151-157
A 13‐year‐old, castrated male Maine Coon cat was presented to Oklahoma State University Boren Veterinary Medical Teaching Hospital for yearly echocardiographic examination monitoring hypertrophic cardiomyopathy (HCM) diagnosed in 2003. Physical examination revealed a heart murmur and premature beats, likely related to HCM, but was otherwise unremarkable. A biochemistry profile revealed a hyperglobulinemia (6.3 g/dL). Cytologic examination of fine‐needle aspirates from liver and spleen revealed increased numbers of plasma cells and mast cells, confirmed with subsequent histologic examination. Immunohistochemistry (IHC) for c‐kit in the spleen and liver showed mast cells predominantly exhibiting type I staining pattern, with moderate numbers exhibiting type II pattern in spleen, and scattered cells exhibiting type II and III patterns in liver. Bone marrow cytology and core biopsy documented approximately 22% plasma cells. Cutaneous masses on the cat's left shoulder and right carpus were cytologically confirmed mast cell tumors. Serum protein electrophoresis with immunofixation confirmed an IgG monoclonal gammopathy. This is an example of 2 hematologic neoplasms occurring simultaneously in a cat. Concurrent pathologies may be overlooked if a single disease is diagnosed and suspected of causing all clinical signs. Both neoplasms were well differentiated, and neoplastic cells could have easily been interpreted as a reactive population had a full workup not been performed. Missing either diagnosis could result in a potentially lethal outcome. Eleven months after diagnoses, the cat was clinically doing well following a splenectomy and oral prednisolone and chlorambucil chemotherapy. Globulins decreased to 4.9 g/dL. 相似文献
60.
Dell M 《The Canadian veterinary journal. La revue veterinaire canadienne》2010,51(12):1405-1407
A 4-week-old male Pomeranian was presented with eyes that had remained closed since birth. Clinical examination of the orbits revealed that globes were bilaterally absent, suggesting clinical anophthalmos. Following ultrasound imaging of the orbits, a diagnosis of severe bilateral microphthalmos was made, a condition of rare occurrence with an etiology that is not fully understood. 相似文献