489,648 research outputs found

    SIMULTANEOUS MEASUREMENT OF AIR-EARTH CURRENT AT TWO STATIONS

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    The air-earth current was measured at two stations in Kyoto city simultaneously in the cold season, 1970 through 1971, obtaining the diurnal variation pattern. Cross correlation coefficient was calculated. It is demonstrated that differences of amplitude and phase of variations at the two stations are due to variations of the columnar resistance at each station. It is found that the columnar resistance is sensitively affected by surface wind

    The geographic mosaic of herbicide resistance evolution in the common morning glory, Ipomoea purpurea: Evidence for resistance hotspots and low genetic differentiation across the landscape

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    Strong human‐mediated selection via herbicide application in agroecosystems has repeatedly led to the evolution of resistance in weedy plants. Although resistance can occur among separate populations of a species across the landscape, the spatial scale of resistance in many weeds is often left unexamined. We assessed the potential that resistance to the herbicide glyphosate in the agricultural weed Ipomoea purpurea has evolved independently multiple times across its North American range. We examined both adaptive and neutral genetic variations in 44 populations of I. purpurea by pairing a replicated dose–response greenhouse experiment with SSR genotyping of experimental individuals. We uncovered a mosaic pattern of resistance across the landscape, with some populations exhibiting high‐survival postherbicide and other populations showing high death. SSR genotyping revealed little evidence of isolation by distance and very little neutral genetic structure associated with geography. An approximate Bayesian computation (ABC) analysis uncovered evidence for migration and admixture among populations before the widespread use of glyphosate rather than the very recent contemporary gene flow. The pattern of adaptive and neutral genetic variations indicates that resistance in this mixed‐mating weed species appears to have evolved in independent hotspots rather than through transmission of resistance alleles across the landscape.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/113156/1/eva12290_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/113156/2/eva12290.pd

    Development of a high efficiency thin silicon solar cell

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    Variations in temperatures used in experimental processing and their effect on the resulting solar cell performance parameters were investigated. Diffusion temperature variation results in a fairly distinct optimum cell performance for diffusion temperatures in the immediate vicinity of 850 C. An additional effort was also devoted to redesign of the matallization gridline pattern for both minimum light blockage and minimum fill factor alteration due to series resistance. Efforts on improvement of tantalum oxide antireflection coatings were undertaken. Fifty 2 cm x 2 cm cells having a range of thicknesses have been submitted as the first sample group. These cells were processed under conditions tentatively identified during this first contractual quarter's experiments as being optimal for resulting cell performance

    DNA polymorphism of 3’ UTR of Nramp1 gene in Malvi breed of cattle

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    The natural resistance-associated macrophage protein 1 gene (Nramp1), which is a member of large family of metal ion–transport protein. Nramp1 gene plays a critical role in innate immunity favoring bacterial killing by macrophages in addition to its influence on adaptive immunity. The aim of the present investigation was to identify the genetic variations in the 3’UTR (Untranslated region) of Nramp1 gene in the Malvi breed (Bos indicus) cattle, using the technique PCR-SSCP and by sequencing. PCR-SSCP (Single Strand conformational polymorphism) of 440 bp amplicon of Nramp1 gene revealed three common SSCP patterns in Malvi breed. A total of 3 SSCP patterns viz Pattern I, Pattern II and Pattern III were observed with frequency of 0.361, 0.426 and 0.213 respectively. The patterns variations were confirmed by cloning and sequencing, which showed total 6 mutations in 3 patterns

    Multidrug Resistance of Uropathogens at Governmental Hospitals in the Gaza Strip/Palestine

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    Urinary tract infection is a public health problem worldwide. E. coli and klebsiella are among the main etiologic for UTI in Gaza Strip. The growing variations in resistance among uropathogens to antimicrobials is multifactorial and varies globally. It greatly reduces/limits or complicate treatment option. Aims: To determine the pattern of antimicrobial resistance and multidrug resistance among uropathogens at governmental hospitals. Methods: We analyzed the data of 11,890 urine samples processed in governmental hospitals in the Gaza Strip, Palestine during 2019. The percentage of resistance was calculated for uropathogens, and then multidrug resistance was calculated according to “CDC†definition. Results: Of 11,890 urine samples, 2910 (24.5%) showed significant growth.  Escherichia coli was isolated most frequently (1743; 59.9%), followed by Klebsiella spp. (725; 24.9%), Pseudomonas spp. (123; 4.2%), Streptococcus spp. (98; 3.4%), Staphylococcus aureus (41; 1.4%). Microorganisms resistance was high against Ampicillin (92.4%) and Amoxicillin (91.1%), Co-Trimoxazole (68.2%), Cefalexin (64.9%), Doxycycline (61.9%), Nalidixic acid (53.6%), Cefuroxime (53.0%), Ceftriaxone (48.9%), Ceftazidime (43.1%), Ciprofloxacin (36.9%), Gentamicin (25.8%), Amikacin (3.2%). The resistance of microorganisms in males is higher than females. Multidrug resistance was detected in 37% of E. coli and 53% in Klebsiella spp. Conclusion: Resistance is high and variable among uropathogens isolated from patients in Gaza strip. Both age and gender are risk factors in both infection and resistance pattern. The multidrug resistance percentage is growing remarkably in Gaza Strip. Keywords: Uropathogens, Resistance, Urinary tract infection, Multidrug resistance, Gaza strip, Palestine &nbsp

    Comparative proteomic analyses of avirulent, virulent and clinical strains of mycobacterium tuberculosis identify strain-specific patterns

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    Mycobacterium tuberculosis is an adaptable intracellular pathogen, existing in both dormant as well as active disease-causing states. Here, we report systematic proteomic analyses of four strains, H37Ra, H37Rv and clinical isolates BND and JAL, to determine the differences in protein expression patterns that contribute to their virulence and drug resistance. Resolution of lysates of the four strains by liquid chromatography, coupled to mass spectrometry analysis, identified a total of 2161 protein groups covering ∼54% of the predicted M. tuberculosis proteome. Label-free quantification analysis of the data revealed 257 differentially expressed protein groups. The differentially expressed protein groups could be classified into seven K-means cluster bins, which broadly delineated strain-specific variations. Analysis of the data for possible mechanisms responsible for drug resistance phenotype of JAL suggested that it could be due to a combination of overexpression of proteins implicated in drug resistance and the other factors. Expression pattern analyses of transcription factors and their downstream targets demonstrated substantial differential modulation in JAL, suggesting a complex regulatory mechanism. Results showed distinct variations in the protein expression patterns of Esx and mce1 operon proteins in JAL and BND strains, respectively. Abrogating higher levels of ESAT6, an important Esx protein known to be critical for virulence, in the JAL strain diminished its virulence, although it had marginal impact on the other strains. Taken together, this study reveals that strain-specific variations in protein expression patterns have a meaningful impact on the biology of the pathogen

    An Approach to Assess Solder Interconnect Degradation Using Digital Signal

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    Department of Human and Systems EngineeringDigital signals used in electronic systems require reliable data communication. It is necessary to monitor the system health continuously to prevent system failure in advance. Solder joints in electronic assemblies are one of the major failure sites under thermal, mechanical and chemical stress conditions during their operation. Solder joint degradation usually starts from the surface where high speed signals are concentrated due to the phenomenon referred to as the skin effect. Due to the skin effect, high speed signals are sensitive when detecting the early stages of solder joint degradation. The objective of the thesis is to assess solder joint degradation in a non-destructive way based on digital signal characterization. For accelerated life testing the stress conditions were designed in order to generate gradual degradation of solder joints. The signal generated by a digital signal transceiver was travelling through the solder joints to continuously monitor the signal integrity under the stress conditions. The signal properities were obtained by eye parameters and jitter, which represented the characteristics of the digital signal in terms of noise and timing error. The eye parameters and jitter exhibited significant increase after the exposure of the solder joints to the stress conditions. The test results indicated the deterioration of the signal integrity resulted from the solder joint degradation, and proved that high speed digital signals could serve as a non-destructive tool for sensing physical degradation. Since this approach is based on the digital signals used in electronic systems, it can be implemented without requiring additional sensing devices. Furthermore, this approach can serve as a proactive prognostic tool, which provides real-time health monitoring of electronic systems and triggers early warning for impending failure.ope
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