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101.
Studies of the spirochete Borrelia burgdorferi have been hindered by the scarcity of genetic tools that can be used in these bacteria. For the first time, a method has been developed by which heterologous DNA (DNA without a naturally occurring B. burgdorferi homolog) can be introduced into and persistently maintained by B. burgdorferi. This technique uses integration of circular DNA into the bacterial genome via a single-crossover event. The ability to transform B. burgdorferi with heterologous DNA will now permit a wide range of experiments on the biology of these bacteria and their involvement in the many facets of Lyme disease. 相似文献
102.
A growth curve analysis was used to examine estimated longitudinal decline (over 19 years) on the Wechsler Adult Intelligence Scale (WAIS; D. Wechsler, 1955) in relation to arterial hypertension and blood pressure (BP) for 55 men and 85 women (40 to 70 years old) who were free from overt major coexisting diseases. BP was associated with longitudinal decline for Visualization-Performance (VP) ability and Speed. Hypertension was a weaker predictor of VP and was unrelated to Speed. Age effects on VP were overestimated when averaged BP level, particularly systolic BP, was not controlled statistically. It was concluded that initial BP level and hypertension predict age-related longitudinal decline in specific major abilities assessed by the WAIS but that BP averaged over examinations is a stronger predictor. 相似文献
103.
This paper deals with the reliability of a renewable three-unit system under preventive maintenance activity. The Laplace transform of the reliability function and the mean lifetime of the system have been obtained under the assumption that the failure times, repair times, inspection times and maintenance times are random variables having different distributions. Some special cases also have been obtained. 相似文献
104.
The UL9 gene of herpes simplex virus type 1 (HSV-1) encodes an origin binding protein (OBP). It is an ATP-dependent DNA helicase and a sequence-specific DNA-binding protein. The latter function is carried out by the C-terminal domain of OBP (DeltaOBP). We have now performed a quantitative analysis of the interaction between DeltaOBP and its recognition sequence, GTTCGCAC, in oriS. Initially optimal conditions for binding were carefully determined. We observed that complexes with different electrophoretic mobilities were formed. A cross-linking experiment demonstrated that nonspecific complexes containing 2 or more protein monomers per DNA molecule were formed at high protein concentrations. The specific complex formed at low concentrations of DeltaOBP had an electrophoretic mobility corresponding to a 1:1 complex. We then demonstrated that the methyl groups of thymine in the major groove were essential for high affinity binding. Changes in the minor groove had considerably smaller effects. Ethylation interference experiments indicated that specific contacts were made between OBP and three phosphates in the recognition sequence. Finally, these observations were used to present a model of the surface of DNA that interacts with DeltaOBP in a sequence-specific manner. 相似文献
105.
Anticentromere antibodies in rheumatologic practice are not consistently associated with scleroderma
F Tubach G Hayem A Elias P Nicaise T Haim MF Kahn O Meyer 《Canadian Metallurgical Quarterly》1997,64(6):362-367
Anticentromere antibodies identified by indirect immunofluorescence are a valuable aid to the diagnosis and prognosis of patients with systemic sclerosis since they are associated in 50% to 80% of cases with limited cutaneous systemic sclerosis, a pattern usually associated with a good prognosis. We studied clinical presentations in rheumatology patients with anticentromere antibodies by indirect immunofluoresence and by ELISA and/or Western blot, but without scleroderma or Raynaud's phenomenon. Eight of 34 (23.5%) rheumatology clinic patients with centromere antibodies met these criteria, seven women and one man, with a median symptom duration of six years (range 1-20 years). Four had Sj?gren's syndrome, one had isolated xerostomia, one systemic lupus erythematosus, one seronegative symmetric polyarthritis and one primary biliary cirrhosis with arthralgia. The mean anticentromere antibody titer in these eight patients was similar to that in the patients who had at least Raynaud's phenomenon. Given the low incidence of scleroderma, these data illustrate the poor predictive value of anticentromere antibodies for the diagnosis of scleroderma in rheumatology clinic patients. 相似文献
106.
Numerous factors related to health and diseases have been studied in relation to cognitive function. It has been shown that across the life span, systemic medical diseases can negatively impact cognitive function. Factors that influence the development of medical diseases, such as poor health habits, biological risk factors, hormones, genetic factors, exposure to environmental toxins, and certain treatments for disease, can also have an adverse effect on cognitive function. Conversely, factors such as high levels of education, good health habits, and some treatments for disease can be protective. Included in this special section are 6 empirical articles that examine the relation of health or disease to cognitive function. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
107.
Wayne C. Westerman David P. M. Northmore John. G. Elias 《Analog Integrated Circuits and Signal Processing》1997,13(1-2):167-184
We describe neuromorphic, variable-weight synapses onartificial dendrites that facilitate experimentation with correlativeadaptation rules. Attention is focused on those aspects of biologicalsynaptic function that could affect a neuromorphic network'scomputational power and adaptive capability. These include sublinearsummation, quantal synaptic noise, and independent adaptationof adjacent synapses. The diffusive nature of artificial dendritesadds considerable flexibility to the design of fast synapsesby allowing conductances to be enabled for short or for variablelengths of time. We present two complementary synapse designs:the shared conductance array and the self-timed synapse. Bothsynapse circuits behave as conductances to mimic biological synapsesand thus enable sublinear summation. The former achieves weightvariation by selecting different conductances from an on-chiparray, and the latter by modulating the length of time a constantconductance remains activated. Both work with our interchip communicationsystem, virtual wires. For the present purpose of comparing variousadaptation mechanisms in software, synaptic weights are storedoff chip. This simplifies the addition of quantal weight noiseand allows connections from different sources to the same dendriticcompartment to have independent weights. 相似文献
108.
Elias Kalapanidas & Nikolaos Avouris 《Computer-Aided Civil and Infrastructure Engineering》2002,17(2):119-130
Management of urban atmospheric pollution necessitates advanced modeling and information processing techniques. The design of the prototype system DNEMO, which is based on a distributed adaptive problem-solving approach is the focus of the research reported in this paper. Issues covered in the paper relate to the distributed nature of this environmental problem, handling noise and uncertainty in monitoring data, achieving graceful degradation of performance and system robustness, and adaptation of system performance to long-term evolution of the monitored phenomena. The research reported can be applicable to a broad class of environmental monitoring applications, since the problems addressed are common to many environmental problems. 相似文献
109.
Nathalie Cayot Philippe Cayot Elias Bou-Maroun Hélène Laboure Beatriz Abad-Romero Karine Pernin Nuria Seller-Alvarez Ayary V. Hernández Elil Marquez & Ana L. Medina 《International Journal of Food Science & Technology》2009,44(11):2303-2313
This study aimed to characterise a non-conventional protein source: a powder made from earthworms, and to evaluate its potential use as human food. The way it was prepared led to low solubility and wide particle size distribution. Sensory analysis was used to assess the acceptability and the organoleptic properties of maize-based pan-cakes fortified with this novel protein powder. Satisfying products were obtained with a substitution level of 5.5% (w/w) earthworm powder in pan-cakes. GC-MS allowed the identification of more than seventy volatile compounds that may be responsible for the off-odour of the powder. The most abundant chemical groups found in the volatile fraction were ketones with undecan-2-one, alcohols with pentan-1-ol, and aldehydes with hexanal. Partial delipidation was tested as a way to improve the organoleptic quality of the powder. It clearly led to less intensely coloured samples but delipidation must be optimised to have an impact on odour. 相似文献
110.