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61.
An improved algorithm for disaggregating microwave-derived soil moisture based on red, near-infrared and thermal-infrared data 总被引:3,自引:0,他引:3
Accurate high-resolution soil moisture data are needed for a range of agricultural and hydrologic activities. To improve the spatial resolution of ∼ 40 km resolution passive microwave-derived soil moisture, a methodology based on 1 km resolution MODIS (MODerate resolution Imaging Spectroradiometer) red, near-infrared and thermal-infrared data has been implemented at 4 km resolution. The three components of that method are (i) fractional vegetation cover, (ii) soil evaporative efficiency (defined as the ratio of actual to potential evaporation) and (iii) a downscaling relationship. In this paper, 36 different disaggregation algorithms are built from 3 fractional vegetation cover formulations, 3 soil evaporative efficiency models, and 4 downscaling relationships. All algorithms differ with regard to the representation of the nonlinear relationship between microwave-derived soil moisture and optical-derived soil evaporative efficiency. Airborne L-band data collected over an Australian agricultural area are used to both generate ∼ 40 km resolution microwave pixels and verify disaggregation results at 4 km resolution. Among the 36 disaggregation algorithms, one is identified as being more robust (insensitive to soil, vegetation and atmospheric variables) than the others with a mean slope between MODIS-disaggregated and L-band derived soil moisture of 0.94. The robustness of that algorithm is notably assessed by comparing the disaggregation results obtained using composited (averaged) Terra and Aqua MODIS data, and using data from Terra and Aqua separately. The error on disaggregated soil moisture is systematically reduced by compositing daily Terra and Aqua data with an error of 0.012 vol./vol. 相似文献
62.
B Sagi S C Nemat-Nasser R Kerr R Hayek C Downing R Hecht-Nielsen 《Neural computation》2001,13(7):1575-1602
We present a new approach to the cocktail party problem that uses a cortronic artificial neural network architecture (Hecht-Nielsen, 1998) as the front end of a speech processing system. Our approach is novel in three important respects. First, our method assumes and exploits detailed knowledge of the signals we wish to attend to in the cocktail party environment. Second, our goal is to provide preprocessing in advance of a pattern recognition system rather than to separate one or more of the mixed sources explicitly. Third, the neural network model we employ is more biologically feasible than are most other approaches to the cocktail party problem. Although the focus here is on the cocktail party problem, the method presented in this study can be applied to other areas of information processing. 相似文献
63.
We compared two gastrin radioimmunoassay kits ("Immutope" kit, Squibb & Co.; "Gastrin R.I.A." kit, Schwarz/Mann) to the conventional gastrin radioimmunoassay of Yalow and Berson [Gastroenterology 58, 1 (1970)] as run by us and by a second reference laboratory. Although both kits were found to effectively discriminate above-normal and normal values for serum gastrin, they significantly underestimated very high values (greater than 1500 ng/liter). The Schwarz/Mann kit clearly had a superior quality label (lower nonspecific binding and higher specific activity) and a shorter incubation time. However, the 90-min incubation period cited for their kit caused overestimation of gastrin values in the lower range (5-300 ng/liter), which could be corrected by prolonging the incubation to 24 h. The Squibb antibody had fairly good cross reactivity to all gastrin species tested; the Schwarz/Mann antibody had poor affinity for natural human gastrin G34-II. Good correspondence was found for sera run by both reference laboratories (y = 0.96x + 10, r = 0.997), and values obtained with the Schwarz/Mann kit correlated best (+ 0.815) with those from the conventional radioimmunoassay procedure. 相似文献
64.
We compared development of feline hindlimb collateral circulation after acute occlusion of the terminal aorta by ligation, thrombus formation, and formation of a "closed" aortic loop containing thromboplastin. Collateral circulation development was assessed by aortograms, scintillation scans, neurological signs following occlusion, measurement of hindlimb muscle blood flow, and forelimb and hindlimb temperature. In cats in which aortic occlusion was the result of ligation or thromboplastin in the aortic loop, paralysis was not evident. Aortograms and scintillation scans indicated hindlimb blood flow. Both muscle temperature and blood flow data indicated that the return of blood flow was rapid. The 5th lumbar artery appears to be the origin of the collateral vessels. The mid-zone component is a dorsal and ventral vertebral route and an epaxial muscle route. The reentry components are the 6th or 7th lumbar arteries. The collateral vessels arise from preexisting collateral vessels. Of those cats in which aortic occlusion was the result of a thrombus, all exhibited paralysis. Aortograms, scintillation scans, muscle temperature, and hindlimb blood flow data indicated reduced hindlimb blood flow. The results suggest that the thrombus has an inhibitory effect on the development of collateral circulation. 相似文献
65.
Bypass surgery for vascular disease of the carotid system 总被引:2,自引:0,他引:2
TM Sundt RG Siekert DG Piepgras FW Sharbrough OW Houser 《Canadian Metallurgical Quarterly》1976,51(11):677-692
A series of 58 operations on 56 patients, in whom a branch of the superficial temporal artery was anastomosed to a branch of the middle cerebral artery (STA-MCA bypass or Yasargil procedure), is reviewed. These operations were performed chiefly for occlussions or for inaccessible stenotic lesions of the internal carotid or middle cerebral arteries. Patency in eight patients operated on from April 1971 through November 1973 was low (25%). Patency in patients operated on since July 1974 has been high (95%). There have been no deaths and no major ischemic strokes attributable to the surgery. The rationale for this procedure is considered in relationship to the anatomy and physiology of the cerebral circulation and the pathogenesis of syndromes of cerebral ischemia. The operation appears to have a low morbidity in good-risk patients. The role of this operation in managing common manifestations of cerebral vascular disease such as focal transient cerebral ischemic attacks (TIAs) and amaurosis fugax, although not fully established, appears encouraging. The procedure seems useful for orthostatic cerebral ischemia caused by multiple occlusions of major extracranial (and intracranial) vessels and, occasionally, for progressing strokes related to internal carotid artery occlusion, both of which are relatively uncommon manifestations of cerebral vascular occlusive disease. It may have application in the rare "slow stroke." The procedure is probably of limited value, if any, in the management of large completed infarcts but may be indicated in selected patients with small infarctions who have preserved most of their cerebral function and who have had evidence of subsequent focal ischemic events. The procedure is useful for bypassing giant aneurysms or basofrontal tumors invading major vessels. It may have a role in the management of fibromuscular disease of the internal carotid artery. 相似文献
66.
Determining degree of roasting in cocoa beans by artificial neural network (ANN)‐based electronic nose system and gas chromatography/mass spectrometry (GC/MS) 下载免费PDF全文
BACKGROUND
Roasting is a critical step in chocolate processing, where moisture content is decreased and unique flavors and texture are developed. The determination of the degree of roasting in cocoa beans is important to ensure the quality of chocolate. Determining the degree of roasting relies on human specialists or sophisticated chemical analyses that are inaccessible to small manufacturers and farmers. In this study, an electronic nose system was constructed consisting of an array of gas sensors and used to detect volatiles emanating from cocoa beans roasted for 0, 20, 30 and 40 min. The several signals were used to train a three‐layer artificial neural network (ANN). Headspace samples were also analyzed by gas chromatography/mass spectrometry (GC/MS), with 23 select volatiles used to train a separate ANN.RESULTS
Both ANNs were used to predict the degree of roasting of cocoa beans. The electronic nose had a prediction accuracy of 94.4% using signals from sensors TGS 813, 826, 822, 830, 830, 2620, 2602 and 2610. In comparison, the GC/MS predicted the degree of roasting with an accuracy of 95.8%.CONCLUSION
The electronic nose system is able to predict the extent of roasting, as well as a more sophisticated approach using GC/MS. © 2018 Society of Chemical Industry 相似文献67.
Changes in the ultrastructure and texture of prawn muscle (Macrobrachuim rosenbergii) during cold storage 总被引:1,自引:0,他引:1
Changes in the ultrastructure and proteolytic activity of prawn muscle were determined during storage at 5 °C, in order to better understand changes in physical and sensory texture measurements. Progressive deterioration of myofibril structure was observed during refrigeration of prawn for 14 d. The loss of density and order in Z-line alignment was first detected after 3 d of storage. Progressive disruption of Z-line, I-bands and M-lines was observed after 4-6 d of storage. Muscle degradation included pronounced disruption of the mitochondria as revealed by swollen cristae, loss of cristae material, and membrane breakage. Along with ultrastructural changes, decreased shear force values and mean textures scores were measured. An initial shear force value of 18.21 N/g decreased to 14.50, 12.46, and 10.79 N/g on days 3, 6, and 14, respectively. Mean texture scores indicated that prawn muscle maintained firm texture during 0-3 d of storage, and became soft during 4-6 d of storage. After 6 d of storage, the prawn texture was very soft. Increased deterioration of the muscle ultrastructure coincided with the increase of proteolytic microorganisms and salt soluble muscle proteins found by Sodium dodecyl sulfate-polyacrylamide gel electrophoresis. It is concluded that the weakening of the ultrastructure is related to proteolytic activity and results in a more soft texture in prawns. 相似文献
68.
E vanSonnenberg GR Wittich KS Chon HB D'Agostino G Casola D Easter RG Morgan EM Walser WH Nealon B Goodacre BE Stabile 《Canadian Metallurgical Quarterly》1997,168(4):979-984
OBJECTIVE: The purpose of our study was to review and report the patient selection, techniques, and results of percutaneous drainage of pancreatic abscesses by retrospective review. MATERIALS AND METHODS: Fifty-nine patients (46 men and 13 women) with a mean age of 44 years old had 80 pancreatic abscesses that were drained percutaneously under radiologic guidance (CT, n = 77; sonography, n = 2; and fluoroscopy, n = 1). Abscesses had a wide spectrum of causes, with alcoholic pancreatitis being most common, trauma second most common, and gallstones third. Ten patients had undergone surgery for pancreatic necrosis or abscess. Patients with pancreatic pseudocysts, necrosis, or acute fluid collections were excluded from this study. RESULTS: Of the 59 patients, 51 (86%) were cured with percutaneous drainage and antibiotic therapy. Of the patients who were not cured with percutaneous drainage, seven required surgery and one underwent repeat percutaneous drainage. In the 59 patients, complications included non-life-threatening bleeding in three patients. Ten of 59 patients (17%) had fistulas that spontaneously formed into the gastrointestinal tract. The duration of catheterization ranged from 4 to 119 days, with a mean duration of 33 days. The rate of mortality at 30 days after completion of percutaneous drainage was 8% (5 of 59). CONCLUSION: Percutaneous drainage was an effective therapy for this defined group of patients with pancreatic abscesses. Factors leading to the relatively high success rate described in this study likely included selection of patients; catheters of adequate size, number, and location; careful follow-up with appropriate catheter manipulations; and an integrated, cooperative approach whereby surgeons were willing to permit drainage to effect its benefits, rather than operating prematurely. 相似文献
69.
Rong Zhang Jie Pan Evan P. Briggs Marvin Thrash Lei L. Kerr 《Solar Energy Materials & Solar Cells》2008,92(4):425-431
The interface between the ZnO and dye directly impacts the dye-sensitized solar cell (DSSC) performance. Nanostructured porous ZnO film was developed by a simple chemical solution process. Scanning electron microscope (SEM) images demonstrated the uniform ZnO films with sheet-like nanostructure. Adsorption studies indicated that the maximum adsorption capacity of RuN3 dye on the surface of ZnO films was approximately 0.016 mmol RuN3/g ZnO films. Adsorption studies were conducted at 25 and 40 °C. The results showed that the dye adsorption was significantly influenced by temperatures. Moreover, the problem of the dye aggregation on the ZnO surface was reduced at higher adsorption temperatures. The adsorption chemistry was studied with Raman spectroscopy. 相似文献
70.
The temperature when the pH=6.0 (temp@pH6) impacts on the tenderness and eating quality of sheep meat. Due to the expense, sarcomere length is not routinely measured as a variable to explain variation in shear force, but whether measures such as temp@pH6 are as useful a parameter needs to be established. Measures of rigor onset in 261 carcases, including the temp@pH6, were evaluated in this study for their ability to explain some of the variation in shear force. The results show that for 1 day aged product combinations of the temp@pH6, the pH at 18 °C and the pH at 24 h provided a larger reduction (almost double) in total shear force variation than sarcomere length alone, with pH at 24 h being the single best measure. For 5 day aged product, pH at 18 °C was the single best measure. Inclusion of sarcomere length did represent some improvement, but the marginal increase would not be cost effective. 相似文献