1,711 research outputs found

    Calibration of averaging total pressure flight wake rake and natural-laminar-flow airfoil drag certification

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    An averaging total pressure wake rake used by the Cessna Aircraft Company in flight tests of a modified 210 airplane with a laminar flow wing was calibrated in wind tunnel tests against a five-tube pressure probe. The model generating the wake was a full-scale model of the Cessna airplane wing. Indications of drag trends were the same for both instruments

    The IT performance evaluation in the construction industry

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    To date there has been limited published work in the construction management and engineering literature that has provided empirical evidence to demonstrate that IT can improve organizational performance. Without an explicit understanding about how IT can be effectively used to improve organizational performance, its justification will remain to be weak for managers. To ensure the continuous increase in IT based applications in the construction industry, sufficient evidence has to be provided for management in various professions of the construction industry to evaluate, allocate and utilize appropriate IT systems. In an attempt to explore the relationship between IT and productivity, an empirical investigation of 60 Professional Consulting Firms (PCF) from the Hong Kong construction industry was undertaken. A model for determining the organizational productivity of IT is proposed, and the methodology used to test the model is described. The findings are analyzed and a cross-profession comparison of the results indicated the differences in the use of IT. The research findings are discussed with similarities being drawn. The limitations of the research are then presented and discussed. The implications of the findings and conclusions then fully presented

    On-Line Paging against Adversarially Biased Random Inputs

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    In evaluating an algorithm, worst-case analysis can be overly pessimistic. Average-case analysis can be overly optimistic. An intermediate approach is to show that an algorithm does well on a broad class of input distributions. Koutsoupias and Papadimitriou recently analyzed the least-recently-used (LRU) paging strategy in this manner, analyzing its performance on an input sequence generated by a so-called diffuse adversary -- one that must choose each request probabilitistically so that no page is chosen with probability more than some fixed epsilon>0. They showed that LRU achieves the optimal competitive ratio (for deterministic on-line algorithms), but they didn't determine the actual ratio. In this paper we estimate the optimal ratios within roughly a factor of two for both deterministic strategies (e.g. least-recently-used and first-in-first-out) and randomized strategies. Around the threshold epsilon ~ 1/k (where k is the cache size), the optimal ratios are both Theta(ln k). Below the threshold the ratios tend rapidly to O(1). Above the threshold the ratio is unchanged for randomized strategies but tends rapidly to Theta(k) for deterministic ones. We also give an alternate proof of the optimality of LRU.Comment: Conference version appeared in SODA '98 as "Bounding the Diffuse Adversary

    Analysis of rs7526084 polymorphism in 3′ downstream of the sestrin 2 gene as an informative marker for molecular diagnosis of kidney stone disease

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    Background: Kidney stone disease is one of the most common disorders of urinary tract, manifesting with high clinical and genetic heterogeneity in population. Sestrin 2 is involved in many essential processes, especially oxidative and genotoxic stress. Regarding the importance of oxidative stress pathway deregulation in systemic diseases such as kidney disorders, this study was conducted to investigate the association between rs7526084 3′ downstream polymorphism of the sestrin 2 gene and risk of kidney stone in south Iranian patients. Materials and Methods: In this case-control study, 150 patients with kidney stone disease and 180 age- and gender-matched healthy individuals were participated from March to December 2015. Genotyping of the rs7526084 polymorphism was performed using the T-ARMS PCR method. Results: Frequency of the G allele was higher in controls than in cases, and a reduced risk of the disease was shown in the presence of this allele (OR: 0.66, 95CI: 0.48-0.91, P=0.01). Also, the risk of the disease was reduced in the presence of heterozygote CG (OR: 0.49, 95CI: 0.30-0.80, P=0.004) and homozygote GG (OR: 0.47, 95CI: 0.23-0.96, P=0.04) genotypes. Under the dominant genetic model for the G allele (GG+GC vs. CC), this allele significantly reduced the risk of the disease (OR: 0.49, 95CI: 0.31- 0.78, P= 0.002). Conclusion: Reduced risk of kidney stone in the presence of the G allele of the sestrin 2 gene polymorphism might provide the evidence in favor of the involvement of the oxidative stress pathway in the pathogenesis of kidney stone disease

    Developing a frame of reference for ex-ante IT/IS investment evaluation

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    Extended Spectrum Beta-Lactamase Carriage State among Elderly Nursing Home Residents in Beirut

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    Introduction. ESBL-producing Enterobacteriaceae can cause severe infections, but they are also isolated from the stool of asymptomatic subjects. Faecal carriage of such organism is poorly understood. Methods. First phase of the study was cross-sectional with prevalence and epidemiology of ESBL faecal carriage in two nursing homes in Beirut: 57 residents in the first (NH1) and 151 residents in the second (NH2). In second phase, faecal swabs from cohort of NH1 residents were examined for carriage at six-week intervals over three-month period. Residents’ charts were reviewed to assess carriage risk factors. Results. Over 3 consecutive samplings at NH1, 81% of residents were at least one-time carriers with 50% at the first round, 60.4% at the second, and 74.5% at the last one. At NH2, 68.2% of residents were carriers. Constipation (in NH1) and antibiotic intake (in NH2) were significantly associated with higher ESBL faecal carriage while the length of stay at the nursing home (in NH2) was associated with less carriage. Conclusion. Faecal carriage of ESBL-producing Enterobacteriaceae is high among nursing home patients in Beirut. The rate of carriage changes rapidly and significantly over time either with multiple factors playing a possible role like outbreak spreading, antibiotic, and health care system exposure

    Active motion of tangentially driven polymers in periodic array of obstacles

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    One key question about transport of active polymers within crowded environments is how spatial order of obstacles influences their conformation and dynamics when compared to disordered media. To this end, we computationally investigate the active transport of tangentially driven polymers with varying degrees of flexibility and activity in two-dimensional square lattices of obstacles. Tight periodic confinement induces notable conformational changes and distinct modes of transport for flexible and stiff active filaments. It leads to caging of low activity flexible polymers inside the inter-obstacle pores while promoting more elongated conformations and enhanced diffusion for stiff polymers at low to moderate activity levels. The migration of flexible active polymers occurs via hopping events, where they unfold to move from one cage to another, similar to their transport in disordered media. However, in ordered media, polymers are more compact and their long-time dynamics is significantly slower. In contrast, stiff chains travel mainly in straight paths within periodic inter-obstacle channels while occasionally changing their direction of motion. This mode of transport is unique to periodic environment and leads to more extended conformation and substantially enhanced long-time dynamics of stiff filaments with low to moderate activity levels compared to disordered media. At high active forces, polymers overcome confinement effects and move through inter-obstacle pores just as swiftly as in open spaces, regardless of the spatial arrangement of obstacles. We explain the center of mass dynamics of semiflexible polymers in terms of active force and obstacle packing fraction by developing an approximate analytical theory.</p

    Agricultural and Natural Resources Awareness Programming: Barriers and Benefits as Perceived by County Extension Agents

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    The study described here assessed Extension agents\u27 perceived barriers and benefits concerning a new Florida agricultural and natural resources awareness initiative and Web site. A total of 186 agents responded to a statewide Web-based needs assessment, for an overall response rate of 58%. Results highlighted several barriers to communicating about agriculture and natural resources, including (a) a lack of interest, knowledge, and awareness among the general public, government, clientele, and media, (b) a lack of agent access to resources/contacts, and (c) inconsistent/ineffective message delivery methods. Concerning the Web site, most respondents wanted information to be presented via fact sheets, economic facts, and downloadable brochures

    Comparison of the tuberculin skin test and the QuantiFERON-TB Gold test in detecting latent tuberculosis in health care workers in Iran

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    OBJECTIVES: The tuberculin skin test (TST) and the QuantiFERON-TB Gold test (QFT) are used to identify latent tuberculosis infections (LTBIs). The aim of this study was to determine the agreement between these two tests among health care workers in Iran. METHODS: This cross-sectional study included 177 tuberculosis (TB) laboratory staff and 67 non-TB staff. TST indurations of 10 mm or more were considered positive. The Student's t-test and the chi-square test were used to compare the mean score and proportion of variables between the TB laboratory staff and the non-TB laboratory staff. Kappa statistics were used to evaluate the agreement between these tests, and logistic regression was used to assess the risk factors associated with positive results for each test. RESULTS: The prevalence of LTBIs according to both the QFT and the TST was 17 (95 confidence interval CI, 12% to 21%) and 16% (95% CI, 11% to 21%), respectively. The agreement between the QFT and the TST was 77.46%, with a kappa of 0.19 (95% CI, 0.04 to 0.34). CONCLUSIONS: Although the prevalence of LTBI based on the QFT and the TST was not significantly different, the kappa statistic was low between these two tests for the detection of LTBIs
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