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11.
We have developed a narrow-band controller in the MHz range, based on a field-programmable gate array. It is used to control the probe beam intensity in frequency-modulated spectroscopy experiments with an acoustooptic modulator. The residual amplitude modulation at the modulation frequency (2.5 MHz) is reduced by 50 dB. The first-harmonic detection of the signals is operated in saturation spectroscopy of I/sub 2/ at 514.5 nm and 501.7 nm. A reduction of the background noise and a large increase in the signal-to-noise ratio are obtained.  相似文献   
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Conducted a study of client expectations of psychological services in Yucatán, Mexico, under the sponsorship of a grant from the Organization of American States. The Expectations about Counseling–Brief form (EAC-B) questionnaire was translated and administered to 488 subjects across age, sex, and experience with psychological services. Subsequent analyses supported the reliability and robustness of the Spanish EAC-B, with factor structure similar to the EAC-B in English. Some relation was found among age, sex, prior counseling experience, and expectations about counseling. Implications of these data for future research and comparison with U.S. subjects are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
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Processing methods used in photonics and nanotechnology possess many limitations restricting their application areas such as high cost, inability to produce fine details, problems with scalability, and long processing time. Proximity field nanopatterning is a lithography method which surpasses these limitations. By using interference patterns produced by a two-dimensional phase mask, the technique is able to generate a submicron detailed exposure on a millimeter-size slab of light sensitive photopolymer, which is then developed like a photographic plate to reveal three-dimensional interference patterns from the phase mask. While it is possible to use simulations to obtain the interference patterns produced by a phase mask, realizing the mask dimensions necessary for producing a desired interference pattern is analytically challenging due to the intricacies of light interactions involved in producing the final interference pattern. An alternative method is to iteratively optimize the phase mask until the interference patterns obtained converge to the desired pattern. However, depending on the optimization technique used, one either risks a significant probability of failure or requires a prohibitive number of iterations. We argue that an optimization technique that is to take advantage of the physics of the problem using machine learning methods (here fuzzy learning) can lead to competent mask design. This technique is described in this letter.  相似文献   
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BACKGROUND: Simultaneous removal of sulfur, nitrogen and carbon compounds from wastewaters is a commercially important biological process. The objective was to evaluate the influence of the CH3COO?/NO3? molar ratio on the sulfide oxidation process using an inverse fluidized bed reactor (IFBR). RESULTS: Three molar ratios of CH3COO?/NO3? (0.85, 0.72 and 0.62) with a constant S2?/NO3? molar ratio of 0.13 were evaluated. At a CH3COO?/NO3? molar ratio of 0.85, the nitrate, acetate and sulfide removal efficiencies were approximately 100%. The N2 yield (g N2 g?1 NO3?‐N consumed) was 0.81. Acetate was mineralized, resulting in a yield of 0.65 g inorganic‐C g?1 CH3COO?‐C consumed. Sulfide was partially oxidized to S0, and 71% of the S2? consumed was recovered as elemental sulfur by a settler installed in the IFBR. At a CH3COO?/NO3? molar ratio of 0.72, the efficiencies of nitrate, acetate and sulfide consumption were of 100%, with N2 and inorganic‐C yields of 0.84 and 0.69, respectively. The sulfide was recovered as sulfate instead of S0, with a yield of 0.92 g SO42?‐S g?1 S2? consumed. CONCLUSIONS: The CH3COO?/NO3? molar ratio was shown to be an important parameter that can be used to control the fate of sulfide oxidation to either S0 or sulfate. In this study, the potential of denitrification for the simultaneous removal of organic matter, sulfide and nitrate from wastewaters was demonstrated, obtaining CO2, S0 and N2 as the major end products. Copyright © 2008 Society of Chemical Industry  相似文献   
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Exploring spatial datasets with histograms   总被引:2,自引:0,他引:2  
As online spatial datasets grow both in number and sophistication, it becomes increasingly difficult for users to decide whether a dataset is suitable for their tasks, especially when they do not have prior knowledge of the dataset. In this paper, we propose browsing as an effective and efficient way to explore the content of a spatial dataset. Browsing allows users to view the size of a result set before evaluating the query at the database, thereby avoiding zero-hit/mega-hit queries and saving time and resources. Although the underlying technique supporting browsing is similar to range query aggregation and selectivity estimation, spatial dataset browsing poses some unique challenges. In this paper, we identify a set of spatial relations that need to be supported in browsing applications, namely, the contains, contained and the overlap relations. We prove a lower bound on the storage required to answer queries about the contains relation accurately at a given resolution. We then present three storage-efficient approximation algorithms which we believe to be the first to estimate query results about these spatial relations. We evaluate these algorithms with both synthetic and real world datasets and show that they provide highly accurate estimates for datasets with various characteristics. Recommended by: Sunil Prabhakar Work supported by NSF grants IIS 02-23022 and CNF 04-23336. An earlier version of this paper appeared in the 17th International Conference on Data Engineering (ICDE 2001).  相似文献   
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Glucose oxidase (EC 1.1.3.4) was immobilized on different polymeric materials using different immobilization techniques (entrapping by γ‐irradiation, and covalent binding using epichlorohydrin). Studies were carried out to increase the thermal stability of glucose oxidase (GOD) for different applications. The activity and stability of the resulting biopolymers have been compared with those of free GOD. The effect of different polyvinyl alcohol/polyacrylamide (PVA/PAAm) compositions of the copolymer carrier on the enzymatic activity of the immobilized GOD was studied. The maximum enzymatic activity was obtained with the composition ratio of PVA/PAAm of 60:40. The behaviour of the free and immobilized enzyme was analysed as a function of pH. A broadening in the pH profile (5.5–8) was observed for immobilized preparations. The activity and stability of the resulting biopolymers produced by immobilization of GOD onto different carriers have been compared, in both aqueous and organic media, with those of the free GOD. The enzyme's tolerance toward both heat and organic solvent was enhanced by immobilization onto polymers. The addition of different concentrations of organic solvents (10–50%, v/v) to the enzyme at higher temperature (60 °C) was found to stabilize the enzyme molecule. The strongest stabilizing effect on the enzymatic activity was achieved at a concentration of 10%. Copyright © 2005 Society of Chemical Industry  相似文献   
20.
We examined the biopsy specimens of 62 patients with diabetic nephropathy to establish whether the myofibroblast (MF) has a role in progressive interstitial fibrosis and to ascertain whether a relationship existed between MF activity and severity of arteriolosclerosis. MF were identified by morphology and alpha smooth muscle actin (alpha SMA) immunostaining. Analysis of vascular injury was performed by counting the number of interstitial arterioles after staining endothelial cells with von Willebrand factor (VWF) antibody. Arteriosclerosis was quantified by using a computer-aided image analyzer to measure the arteriolar wall surface and total arteriolar surface area, and the ratio of wall to total surface area was expressed as the index of arteriosclerosis (IA). Fractional area of interstitium (IFA), alpha SMA, and collagen III (Coll III) were quantitated by point counting. Results were related to structural and functional parameters using rank correlation coefficients. There was a strong correlation between IFA and Coll III staining (r = 0.83; P < 0.001). The alpha SMA staining correlated with IFA (r = 0.56; P < 0.001) and Coll III (r = 0.47; P < 0.001), and there were significant correlations between alpha SMA and total urinary protein (r = 0.47; P < 0.001), renal function (plasma creatinine) at time of biopsy (r = 0.51; P < 0.001), and the percent change in plasma creatinine after 4 years (delta Cr) (r = 0.37; P = 0.01). The IA correlated significantly with Coll III (r = 0.29; P = 0.02), glomerular filtration rate (GFR) (r = 0.39; P = 0.008), and creatinine (r = 0.33; P = 0.01), but no correlation was observed between alpha SMA and IA (r = 0.16; P = 0.23) or IA and delta Cr (r = -0.04; P = 0.6). Strong correlations could be shown between arteriolar density, IFA (r = 0.75; P < 0.001), alpha SMA (r = -0.36; P = 0.034), and Coll III (r = -0.66; P < 0.0001). The MF appears to have a significant role in the progression of diabetic nephropathy. Ischemia secondary to arteriosclerosis may contribute to interstitial fibrosis through fibroblast modulation into MF.  相似文献   
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