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91.
Superantigens stimulate T-lymphocyte proliferation and cytokine production, but the effects of superantigen exposure on cell function within a complex, highly regulated immune response remain to be determined. In this study, we demonstrate that superantigen exposure significantly alters the murine host response to bacterial antigens in an in vitro coculture system. Two days after exposure to the superantigen staphylococcal enterotoxin B, splenocytes cultured with Streptococcus mutans produced significantly greater amounts of gamma interferon (IFN-gamma) and interleukin-12 than did sham-injected controls. The majority of IFN-gamma production appeared to be CD8(+) T-cell derived since depletion of this cell type dramatically reduced the levels of IFN-gamma. To study host cell damage that may occur following superantigen exposure, we analyzed cytotoxicity to "bystander" fibroblast cells cultured with splenocytes in the presence of bacterial antigens. Prior host exposure to staphylococcal enterotoxin B significantly enhanced fibroblast cytotoxicity in the presence of bacteria. Neutralization of IFN-gamma decreased the amount of cytotoxicity observed. However, a greater reduction was evident when splenocyte-bacterium cocultures were separated from the bystander cell monolayer via a permeable membrane support. Increased cytotoxicity appears to be primarily dependent upon cell-cell contact. Collectively, these data indicate that overproduction of inflammatory cytokines may alter the activity of cytotoxic immune cells. Superantigen exposure exacerbates cytokine production and lytic cell activity when immune cells encounter bacteria in vitro and comparable activities could possibly occur in vivo. 相似文献
92.
An experimental and computational protocol was established for the simultaneous determination of several key gasoline properties from a single Fourier transform infrared (FT-IR) spectrum. The study has shown that midband FT-IR spectroscopy combined with multivariate calibration analysis is a versatile, efficient, and accurate technique for the simultaneous estimation of key gasoline properties within about 1 min with less than 2 mL of sample. The FT-IR-derived values of gasoline properties include research and motor octane numbers, aromatic, olefinic, and saturated hydrocarbon content, benzene content, and concentrations of ethanol, methyl tert-butyl ether, and total oxygen. Concentrations of other oxygenated compounds are expected to be equally predictable. However, since these oxygen-containing species have not been adequately represented among the currently commercially available gasoline samples, their calibration may only be achieved using laboratory fuel blends. Midrange boiling point data may also be estimated. Fuel properties determined by minor concentrations of fuel components, e.g., flash point, sulfur content, etc., may not be modeled because the corresponding FT-IR signals are below detection limits of presented experimental protocol. The precision of this procedure was shown to be comparable to reproducibility of the standard laboratory analyses used for direct measurement of specific fuel properties, with squared correlation coefficient (R(2)) ranging from 0.94 to 0.99 between the two sets of measurements. This new methodology could increase the corresponding output of the petroleum laboratories by a factor of over 200 to 1 while maintaining data integrity and minimizing sample requirements, environmental hazards, and cost. 相似文献
93.
Ohad Gur Manav Bhatia William H. Mason Joseph A. Schetz Rakesh K. Kapania Taewoo Nam 《Structural and Multidisciplinary Optimization》2011,44(2):277-298
The paper describes the development of a multidisciplinary design optimization framework for conceptual design of truss-braced
wing configurations. This unconventional configuration requires specialized analysis tools supported by a modular and flexible
framework to accommodate different configurations. While the previous framework developed at Virginia Tech was a monolithic
Fortran-77 code, the need for more flexibility for complex truss-braced wing configurations was addressed by the development
of this new framework, which is based on Phoenix Integration ModelCenterTM environment. The framework uses updated structural and aerodynamic design modules that enable a more general geometry definition.
The new framework, thus, provides a foundation for future design concepts, especially multi-member truss-braced wing configurations.
The fuel saving potential of these truss-braced wing configurations is presented by comparing different truss designs with
gradually increased level of complexity. 相似文献
94.
Lars Mönch John W. Fowler Stéphane Dauzère-Pérès Scott J. Mason Oliver Rose 《Journal of Scheduling》2011,14(6):583-599
In this paper, we discuss scheduling problems in semiconductor manufacturing. Starting from describing the manufacturing process,
we identify typical scheduling problems found in semiconductor manufacturing systems. We describe batch scheduling problems,
parallel machine scheduling problems, job shop scheduling problems, scheduling problems with auxiliary resources, multiple
orders per job scheduling problems, and scheduling problems related to cluster tools. We also present important solution techniques
that are used to solve these scheduling problems by means of specific examples, and report on known implementations. Finally,
we summarize some of the challenges in scheduling semiconductor manufacturing operations. 相似文献
95.
Sound is an integral part of most movies and videos. In many situations, viewers of a video are unable to hear the sound track, for example, when watching it in a fast forward mode, viewing it by hearing‐impaired viewers or when the plot is given as a storyboard. In this paper, we present an automated visualization solution to such problems. The system first detects the common components (such as music, speech, rain, explosions, and so on) from a sound track, then maps them to a collection of programmable visual metaphors, and generates a composite visualization. This form of sound visualization, which is referred to as SoundRiver, can be also used to augment various forms of video abstraction and annotated key frames and to enhance graphical user interfaces for video handling software. The SoundRiver conveys more semantic information to the viewer than traditional graphical representations of sound illustration, such as phonoautographs, spectrograms or artistic audiovisual animations. 相似文献
96.
DW Morck JK Merrill BE Thorlakson ME Olson LV Tonkinson JW Costerton 《Canadian Metallurgical Quarterly》1993,202(2):273-277
The prophylactic administration of injectable tilmicosin for pneumonia in weaned beef calves was investigated in 1,806 animals. Comparisons were made among calves receiving an "on-arrival" injection of tilmicosin, calves receiving a single injection of long-acting oxytetracycline, and calves receiving no prophylaxis. Morbidity and mortality attributable to pneumonia, morbidity and mortality attributable to all causes, and case fatality were significantly lower in the group of calves that received tilmicosin, compared with calves that received long-acting oxytetracycline and calves that received no prophylactic antibiotic. Mean time to initial pneumonia treatment was significantly extended in calves that received prophylaxis, compared with those that received no antibiotic on arrival at the feedlot. Calves that received tilmicosin gained significantly more weight than calves that received oxytetracycline. Calves that were not treated for pneumonia during the trial period gained significantly more weight than did those calves that were treated for pneumonia regardless of experimental group. The majority of mortalities were attributable to fibrinous pneumonia (31/34). Important bacterial isolates (Pasteurella spp, Haemophilus somnus, Actinomyces pyogenes) obtained at necropsy did not have resistance to tilmicosin in association with administration of tilmicosin as prophylaxis for pneumonia. However, bacterial resistance to trimethoprim/sulfonamide and to oxytetracycline were commonly found in these postmortem isolates. 相似文献
97.
Technetium-99m-1,1-ethyl cysteinate dimer (ECD) has been proposed as a "chemical microsphere" for SPECT measurement of regional cerebral blood flow (rCBF). However, its distribution has not yet been compared in humans to an established rCBF measure. Therefore, we compared the uptake and distribution of ECD with rCBF measured by 133Xe SPECT in subjects with mild to moderate flow abnormalities and in normal volunteers. Blood and urine chemistries and vital signs were unchanged from pre-ECD values up to seven days postinjection. Profile plots demonstrated pattern agreement between rCBF ratios (133Xe) and ECD count density ratios. A significant correlation of rCBF ratios to ECD count density ratios was observed (r = 0.77), with a slope of 0.64 and intercept of 0.36. To explore whether or not the relationship between rCBF and ECD was dependent on absolute flow, ECD region of interest data were expressed in units of ml/min/100 g by equating global CBF (133Xe) and ECD global count density. A closer correlation (r = 0.88) was found for these data than for the count ratio data. The slope was closer to one (m = 0.83) and the intercept was closer to zero (b = 8.2). Also, a significant correlation was observed between ECD-derived rCBF and 133Xe rCBF in the lesion area (r = 0.92) for patients with well-demarcated rCBF lesions. The slope (0.80) suggested a slight underestimation of lesion flow by ECD. Finally, ECD clearance from cortical gray matter ROIs derived from high-resolution scans from 1 to 4 hr postinjection was slow (2.4%/hr). In summary, ECD is a safe and effective marker of regional cerebral perfusion. The distribution of ECD is linearly related to rCBF measured by 133Xe SPECT, although our data suggest a mild underestimation of flow at the high end of the normal range. 相似文献
98.
It is believed that mammalian chemosensory irritants are not aversive to birds and vice versa. Nevertheless, few avian repellents have been tested against mammals. For that reason, we evaluated the efficacy of 1.0% w/v methyl anthranilate, orthoaminoacetophenone, 2-amino-4,5-methoxyacetophenone, 2-methoxyacetophenone, and veratryl amine as mouse repellents in 3-hr no-choice drinking tests. Relative to ingestion of plain water, all test substances significantly reduced (P < 0.05) intake. Orthoaminoaceto-phenone was the most effective repellent, with intake reduced to levels statistically indistinguishable from zero. 相似文献
99.
Stephen Mason 《Computer Fraud & Security》2003,2003(1):13-15
The use of email and the Internet has added a new conduit to market for business, and some organizations have gained significant commercial advantage from using the Internet. Before computers were connected to the Internet, it was relatively easy to have effective security measures in place to protect the electronic files on individual computers or systems. However, now computers have become communication systems as well as working tools, the risks attendant upon this new breed of ‘communications working platform’ have increased substantially. 相似文献
100.
Lessons and Challenges from Mining Retail E-Commerce Data 总被引:1,自引:0,他引:1
The architecture of Blue Martini Software's e-commerce suite has supported data collection, data transformation, and data mining since its inception. With clickstreams being collected at the application-server layer, high-level events being logged, and data automatically transformed into a data warehouse using meta-data, common problems plaguing data mining using weblogs (e.g., sessionization and conflating multi-sourced data) were obviated, thus allowing us to concentrate on actual data mining goals. The paper briefly reviews the architecture and discusses many lessons learned over the last four years and the challenges that still need to be addressed. The lessons and challenges are presented across two dimensions: business-level vs. technical, and throughout the data mining lifecycle stages of data collection, data warehouse construction, business intelligence, and deployment. The lessons and challenges are also widely applicable to data mining domains outside retail e-commerce. 相似文献