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81.
X-ray powder diffraction data are presented for some normal alkyl esters of two octadecenoic acids. The crystal long spacings observed for esters of elaidic acid are shown to be linearly related to the length of the carbon chain of the ester group. Little difference in crystal long spacings was observed between esters ofcis andtrans acids. Melting points of alkyl esters of elaidic acid are reported.  相似文献   
82.
A worker noted a small wound to his thumb when leaving a work site that was undergoing decontamination because of past operations with plutonium (Pu) and americium (Am). Direct surveys of the wound site confirmed the presence of contamination. The chelating agent Ca-DTPA was administered via a nebuliser within an hour after discovery of the wound. External measurements were made of the wound site and wound dressings; 24-h urinary excretion data were collected periodically and the Pu and Am urine content was determined. Zn-DTPA was administered on three occasions. The ICRP Pu systemic model was modified to consider the enhanced urinary excretion following administration of the chelating agents. The analysis indicated that the wound resulted in an initial deposition of 400 Bq 238Pu, 2240 Bq (239/240)Pu and 1060 Bq 241Am. About 70% of the initial wound activity was removed by surgical procedures and less than 1% of the wound activity was removed by chelation therapy. This paper compares the observed urinary excretion data with that indicated by a simulation of the kinetics of the transfer from the wound site and the kinetics of the chelating agent and Pu.  相似文献   
83.
When a set of bioassay data is given to two different dosimetrists, it is likely that these data will be interpreted differently, that different methods and dosimetric models will be applied and therefore different numerical values will be obtained. Thus, it is important for laboratories dealing with internal dosimetry to undergo performance testing procedures such as interlaboratory comparisons of bioassay data interpretation. Several intercomparison exercises have already been organised at national and international levels. The largest one so far was the 3rd European Intercomparison Exercise on Internal Dose Assessment, which has been organised in the framework of the EULEP/EURADOS Action Group, 'Derivation of parameter values for application to the new model of the human respiratory tract for occupational exposure'. The most important lesson learned from these intercomparison exercises was the need to develop agreed guidelines for internal dose evaluation procedures to promote harmonisation of assessments between organisations and countries.  相似文献   
84.
The proteins streptavidin and avidin were electrochemically detected in solution by adsorptive transfer stripping square wave voltammetry (AdTS SWV) at a carbon paste electrode (CPE). AdTS SWV was used to quantify biotinylated oligonucleotides, DNA hybridizations, and avidin in extracts of transgenic avidin maize. The detection limits of denatured and native streptavidin were 6 pM and 120 nM, respectively. The results demonstrated that streptavidin/avidin AdTS SWV is a sensitive and specific method for quantifying DNA and proteins in biological samples such as foods and tissue extracts, including genetically modified crops (avidin maize) and other plants in neighboring fields.  相似文献   
85.
Recent declines in milk prices in the United States have sparked renewed concern that imports of milk protein concentrates (MPC) are increasingly entering the United States with very low tariff rates and is having an adverse impact on the US dairy industry. Milk protein concentrates are used in the United States in many different products, including the starter culture of cheese, or in nonstandard cheeses such as baker's cheese, ricotta, Feta and Hispanic cheese, processed cheese foods, and nutritional products. One of the difficult aspects of trying to assess the impact of MPC imports on the US dairy industry is to quantify the protein content of these imports. The protein content of MPC imports typically ranges from 40 to 88%. The purpose of this study is to develop a methodology that can be used to estimate the protein content of MPC on a country by country basis. Such an estimate would not only provide information regarding the quantity of protein entering the United States, but would also provide a profile of low- and high-value MPC importers. This is critical for market analysis, since it is the lower valued MPC imports that more directly displaces US-produced skim milk powder.  相似文献   
86.
The Measurements of Pollution in the Troposphere (MOPITT) instrument, which was launched aboard the Earth Observing System (EOS) Terra spacecraft on 18 December 1999, is designed to measure tropospheric CO and CH(4) by use of a nadir-viewing geometry. The measurements are taken at 4.7 mum in the thermal emission and absorption for the CO mixing ratio profile retrieval and at 2.3 and 2.2 mum in the reflected solar region for the total CO column amount and CH(4) column amount retrieval, respectively. To achieve the required measurement accuracy, it is critical to identify and remove cloud contamination in the radiometric signals. We describe an algorithm to detect cloudy pixels, to reconstruct clear column radiance for pixels with partial cloud covers, and to estimate equivalent cloud top height for overcast conditions to allow CO profile retrievals above clouds. The MOPITT channel radiances, as well as the first-guess calculations, are simulated with a fast forward model with input atmospheric profiles from ancillary data sets. The precision of the retrieved CO profiles and total column amounts in cloudy atmospheres is within the expected ?10% range. Validations of the cloud-detecting thresholds with the moderate-resolution imaging spectroradiometer airborne simulator data and MOPITT airborne test radiometer measurements were performed. The validation results showed that the MOPITT cloud detection thresholds work well for scenes covered with more than 5-10% cloud cover if the uncertainties in the model input profiles are less than 2 K for temperature, 10% for water vapor, and 5% for CO and CH(4).  相似文献   
87.
Mining minimal distinguishing subsequence patterns with gap constraints   总被引:1,自引:4,他引:1  
Discovering contrasts between collections of data is an important task in data mining. In this paper, we introduce a new type of contrast pattern, called a Minimal Distinguishing Subsequence (MDS). An MDS is a minimal subsequence that occurs frequently in one class of sequences and infrequently in sequences of another class. It is a natural way of representing strong and succinct contrast information between two sequential datasets and can be useful in applications such as protein comparison, document comparison and building sequential classification models. Mining MDS patterns is a challenging task and is significantly different from mining contrasts between relational/transactional data. One particularly important type of constraint that can be integrated into the mining process is the gap constraint. We present an efficient algorithm called ConSGapMiner (Contrast Sequences with Gap Miner), to mine all MDSs satisfying a minimum and maximum gap constraint, plus a maximum length constraint. It employs highly efficient bitset and boolean operations, for powerful gap-based pruning within a prefix growth framework. A performance evaluation with both sparse and dense datasets, demonstrates the scalability of ConSGapMiner and shows its ability to mine patterns from high dimensional datasets at low supports.  相似文献   
88.
The study was a randomized placebo-controlled trial testing whether fluoxetine selectively enhances cessation for smokers with a history of depression. Euthymic smokers with (H+, n = 109) or without (H-, n = 138) a history of major depression received 60 mg fluoxetine or placebo plus group behavioral quit-smoking treatment for 12 weeks. Fluoxetine initially enhanced cessation for H+ smokers (p = .02) but subsequently impaired cessation regardless of depressive history. Six months after quit date, fluoxetine-treated participants were 3.3 times more likely to be smoking (p = .02). Further research is warranted to determine why high-dose fluoxetine produces continuing effects that oppose tobacco abstinence. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
89.
Abstract

Pulsed laser induced surface damage experiments were made on the cleaved (001) face of (—)2-(α-methylbenzylamino)-5-nitropyridine (MBANP) crystals using a pulse length of 25 ns FWHM. The highest single pulse damage threshold value was 24·2 J cm?2 at a wavelength of 1064 nm for light polarized along the crystallographic a axis, whereas the lowest was 1·8 J cm?2 at 532 nm for light polarized along the crystallographic b axis. The extent of the mechanical distortion of the (001) crystal plane consequent upon the absorption of a 25 ns FWHM, 10 J cm?2 pulse from a Nd:YAG laser operating at the wavelength 1064 nm has been measured by a non-destructive and non-invasive technique.  相似文献   
90.
The principle of insulin delivery by ex-vivo somatic cell gene therapy involves the removal of non-B-cell somatic cells (e.g. fibroblasts) from a diabetic patient, and genetically altering them in vitro to produce and secrete insulin. The cells can be grown in culture and returned to the donor as a source of insulin replacement. Cells modified in this way could be evaluated before implantation, and reserve stocks could be cryopreserved. By using the patient's own cells, the procedure should obviate the need for immunosuppression and overcome the problem of tissue supply, while avoiding a recurrence of cell destruction. Ex-vivo somatic cell gene therapy requires an accessible and robust cell type that is amenable to multiple transfections and subject to controlled proliferation. Special problems associated with the use of non-B-cell somatic cells include the processing of proinsulin to insulin, and the conferment of sensitivity to glucose-stimulated proinsulin biosynthesis and regulated insulin release. Preliminary studies using fibroblasts, pituitary cells, kidney (COS) cells and ovarian (CHO) cells suggest that these challenges could be met, and that ex-vivo somatic cell gene therapy offers a feasible approach to insulin replacement therapy.  相似文献   
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