To determine whether US residents are infected with subtypes of human immunodeficiency virus (HIV) type 1 other than subtype B (Western), the predominant North American subtype with a unique GPGR genetic sequence in the V3 loop, viruses from 22 HIV-infected adults were serotyped and subtyped. Twenty patients had subtype B (Western), of whom 15 had serotype B (Western), 3 had serotype A/C, 1 had serotype B (Thai), and 1 had a nontypeable serotype. Two had subtype A, both serotype A/C. Both subtype A-infected patients, only 1 of whom had been outside the United States, reported sex with persons traveling abroad, suggesting possible acquisition in the United States. Because US residents are infected with non-subtype B (Western) strains, US surveillance for HIV-1 diversity is needed to elucidate subtype-specific transmission patterns and pathogenesis and to guide evaluation and development of HIV diagnostic tests and vaccines. 相似文献
Extensive areas of necrosis are present in the early human placental bed. Our aim was to determine whether apoptosis is also a feature. A method was therefore required to differentiate unequivocally necrosis and apoptosis. Initially, terminal deoxynucleotide transferase-mediated dUTP nick-end labelling was used to visualize apoptotic cells. However, non-specific labelling, probably due to free DNA released by necrotic cells, was excessive; thus, in-situ DNA ligation was employed. In this technique, two DNA fragments with single-base 3' overhangs and blunt-ends were labelled with a fluorochrome and then ligated to the DNA breaks on the sections. Immunolabelling for cytokeratin or leukocyte common antigen was performed to determine the phenotype of apoptotic cells identified by the in-situ DNA ligation technique. A proportion of the dying cells was confirmed to be trophoblasts. No co-localization with leukocyte common antigen was found in this region, suggesting that maternal macrophages and natural killer cells (CD56+) were not dying by apoptosis in significant numbers. In conclusion, in-situ DNA ligation in association with immunocytochemistry can readily distinguish apoptosis from necrosis in the placental bed. The results suggest that a proportion of invading trophoblast cells are eliminated by apoptosis in early pregnancy. 相似文献
This paper reviews some knowledge representation approaches devoted to the sensor fusion problem, as encountered whenever images, signals, text must be combined to provide the input to a controller or to an inference procedure. The basic steps involved in the derivation of the knowledge representation scheme, are:
locate a representation, based on exogeneous context information
compare two representations to find out if they refer to the same object/entity
merge sensor-based features from the various representations of the same object into a new set of features or attributes,
aggregate the representations into a joint fused representation, usually more abstract than each of the sensor-related representations.
The importance of sensor fusion stems first from the fact that it is generally correct to assume that improvements in control law simplicity and robustness, as well as better classification results, can be achieved by combining diverse information sources. The second element, is that, e.g., spatially distributed sensing, or otherwise diverse sensing, does indeed require fusion as well. 相似文献
Electrospinning of a segmented copolymer having polyglycolide hard segments is successfully performed from 1,1,1,3,3,3‐hexafluoroisopropanol solutions. During the process, a bactericidal agent, i.e., chlorhexidine (CHX), is effectively loaded, which results in nanofibers with a smaller diameter because of the change in solution conductivity. New fabrics based on molding of alternate layers of poly(ε‐caprolactone) (PCL) films and the electrospun scaffolds of the segmented copolymer are prepared and characterized. The thermal molding process renders a PCL matrix homogeneously reinforced with nanofibers that compensate for the loss of mechanical properties caused by incorporation of CHX. Release of CHX is evaluated in different media. Results vary depending on the layer where the drug is incorporated. Thus, systems with an immediate bacteriostatic effect, as well as systems with a potential long term antimicrobial effect, are obtained. Growth inhibition and adhesion assays demonstrate the fast bactericidal effect of samples with CHX loaded in its outer layers. 相似文献
The crucial significance of proper management of heating, ventilating, and air conditioning systems in energy-efficient buildings were the main reason for dedicating this study to test a novel approach for this task. Shuffled complex evolution (SCE) is an efficient metaheuristic technique that is used to optimize the performance of a multi-layer perceptron neural network (MLP) for accurate prediction of cooling load (CL). The CL information of 768 residential buildings, obtained from a vast computer simulation in the published literature, is used to train and validate the performance of the proposed model. The results showed that the SCE could properly surmount the computational drawbacks of the MLP, as its learning and prediction accuracies are enhanced by 19.52 and 22.84%, respectively. Also, the SCE outperformed two benchmark optimizers of moth–flame optimization and optics inspired optimization in both training and testing phases. Another advantage of the tested SCE-MLP was the considerably simpler structure, and consequently, shorter computation time (722 vs. 1050 and 46,192 s). Therefore, the proposed model can be promisingly used in practice for the early prediction of CL in energy-efficient buildings.
This work presents an automated solution for tool changing in industrial robots using visual servoing and sliding mode control. The robustness of the proposed method is due to the control law of the visual servoing, which uses the information acquired by a vision system to close a feedback control loop. Furthermore, sliding mode control is simultaneously used in a prioritised level to satisfy the constraints typically present in a robot system: joint range limits, maximum joint speeds and allowed workspace. Thus, the global control accurately places the tool in the warehouse, but satisfying the robot constraints. The feasibility and effectiveness of the proposed approach is substantiated by simulation results for a complex 3D case study. Moreover, real experimentation with a 6R industrial manipulator is also presented to demonstrate the applicability of the method for tool changing. 相似文献
Recent studies have demonstrated the high efficiency of metaheuristic algorithms for various optimization engineering problems. The main focus of the present study is to apply a novel notion of stochastic search methods, namely evaporation rate-based water cycle algorithm (ER-WCA) to the problem of soil shear strength (SSS) prediction. The ER-WCA, as the name indicates, is a modified version of the water cycle algorithm that is used to computationally modify an artificial neural network (ANN) for the mentioned purpose. The sensitivity analysis showed that the most proper values for the number of rivers + sea and the population size are 5 and 300, respectively. The performance of the ER-WCA–ANN hybrid is compared to an ANN typically trained by the Levenberg–Marquardt algorithm to evaluate the effectiveness of the proposed metaheuristic technique. The findings showed that incorporation of the ER-WCA results in reducing the root-mean-square error by 5.87% and 4.92% in the training and testing phases, respectively. Meanwhile, the coefficient of determination rose from 84.27 to 86.11% and from 78.80 to 80.83% in these phases. It indicates that the weights and biases suggested by the ER-WCA can construct a considerably more reliable ANN. Therefore, the introduced method is recommended for practical uses in the early prediction of the SSS in civil engineering projects.
Bioassay responses inCotesia marginiventris (Cresson) females to materials derived from fall armyworm (FAW) larvae,Spodoptera frugiperda (J. E. Smith), were most intense for frass and somewhat less intense for larval and pupal cutical materials, scales, exuviae, silk, and oral secretion, with FAW larval hemolymph eliciting only a slight response. The highest percentage of ovipositor probing was caused by frass (100%) and moth scales (90%). Various types of corn-leaf damage when assayed alone did not produce responses as intense as when assayed in combination with frass, cuticle material, and oral secretion. Parasitoid response was somewhat better to frass derived from FAW larvae feeding on corn and peanut leaves than from larvae feeding on the foliage of soybeans, Bermuda grass, cowpeas, or laboratory diet. Hexane and chloroform were better than methanol and water for extracting active material from FAW frass, and chloroform was the best of these solvents for extracting corn leaves. Serial dilutions of frass extracts resulted in a reduction in parasitoid response.This paper was submitted in partial fulfillment of the requirements for Doctor of Philosophy, Department of Entomology and Nematology, University of Florida, Gainesville. 相似文献