1,326 research outputs found

    Advance crew procedures development techniques: Procedures generation program requirements document

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    The Procedures Generation Program (PGP) is described as an automated crew procedures generation and performance monitoring system. Computer software requirements to be implemented in PGP for the Advanced Crew Procedures Development Techniques are outlined

    Genetic Map of Bacteriophage [var phi]X174

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    Bacteriophage [var phi]X174 temperature-sensitive and nonsense mutations in eight cistrons were mapped by using two-, three-, and four-factor genetic crosses. The genetic map is circular with a total length of 24 × 10−4wt recombinants per progeny phage. The cistron order is D-E-F-G-H-A-B-C. High negative interference is seen, consistent with a small closed circular deoxyribonucleic acid molecule as a genome

    Replication forks are underrepresented in chromosomal DNA of Xenopus laevis embryos.

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    Temporal changes in temperature may suggest microhabitat shifts in larval spongillafly Climacia areolaris Hagen (Neuroptera: Sisyridae) abundance and density in a temperate freshwater lake

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    Abiotic factors such as temperature and depth are known to affect aquatic insect populations and are thought to be major variables that directly impact how communities are assembled and populations distributed. The purpose of this study was to examine the role of temperature and depth in structuring C. areolaris populations within a temperate freshwater quarry. Larval densities among individual sponges at different depths were determined over six months in a Pennsylvania quarry. Sponges from four depths (7.0 - 8.0 m; 8.1 - 9.0 m; 9.1 - 10.0 m and 10.1 - 12.0) were collected once per month (n = 3) using SCUBA. Temperature data were collected at four depths (n = 3 samples/depth). Larval densities significantly varied over the study period, but were not significantly different between depths on any date. Mean total larval density was significantly higher in March, April and May compared to dates later in the season. This result followed an inverse pattern where there was a significant effect of date on temperature, but no difference between depths. There was a detectable change in relative abundance of the sisyrid populations among the depths; the two shallowest depth ranges collectively represented \u3e50% of the population during March and April, but were \u3c 50% throughout the rest of the summer. There was also a significant negative relationship of larval density with temperature. Few studies have documented the role of abiotic factors such as depth and temperature on the spatial and temporal structuring of spongillafly microdistribution within a quarry environment

    Crew procedures development techniques

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    The study developed requirements, designed, developed, checked out and demonstrated the Procedures Generation Program (PGP). The PGP is a digital computer program which provides a computerized means of developing flight crew procedures based on crew action in the shuttle procedures simulator. In addition, it provides a real time display of procedures, difference procedures, performance data and performance evaluation data. Reconstruction of displays is possible post-run. Data may be copied, stored on magnetic tape and transferred to the document processor for editing and documentation distribution

    Advanced crew procedures development techniques

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    The development of an operational computer program, the Procedures and Performance Program (PPP), is reported which provides a procedures recording and crew/vehicle performance monitoring capability. The PPP provides real time CRT displays and postrun hardcopy of procedures, difference procedures, performance, performance evaluation, and training script/training status data. During post-run, the program is designed to support evaluation through the reconstruction of displays to any point in time. A permanent record of the simulation exercise can be obtained via hardcopy output of the display data, and via magnetic tape transfer to the Generalized Documentation Processor (GDP). Reference procedures data may be transferred from the GDP to the PPP

    Identifying the Achilles heel of multi-host pathogens : the concept of keystone 'host' species illustrated by Mycobacterium ulcerans transmission

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    Pathogens that use multiple host species are an increasing public health issue due to their complex transmission, which makes them difficult to mitigate. Here, we explore the possibility of using networks of ecological interactions among potential host species to identify the particular disease-source species to target to break down transmission of such pathogens. We fit a mathematical model on prevalence data of Mycobacterium ulcerans in western Africa and we show that removing the most abundant taxa for this category of pathogen is not an optimal strategy to decrease the transmission of the mycobacterium within aquatic ecosystems. On the contrary, we reveal that the removal of some taxa, especially Oligochaeta worms, can clearly reduce rates of pathogen transmission, and these should be considered as keystone organisms for its transmission because they lead to a substantial reduction in pathogen prevalence regardless of the network topology. Besides their potential application for the understanding of M. ulcerans ecology, we discuss how networks of species interactions can modulate transmission of multi-host pathogens

    Buruli ulcer disease prevalence in Benin, West Africa: associations with land use/cover and the identification of disease clusters

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    © 2008 Wagner et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution Licens

    Microbial Biofilm Community Variation in Flowing Habitats: Potential Utility as Bioindicators of Postmortem Submersion Intervals

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    Biofilms are a ubiquitous formation of microbial communities found on surfaces in aqueous environments. These structures have been investigated as biomonitoring indicators for stream heath, and here were used for the potential use in forensic sciences. Biofilm successional development has been proposed as a method to determine the postmortem submersion interval (PMSI) of remains because there are no standard methods for estimating the PMSI and biofilms are ubiquitous in aquatic habitats. We sought to compare the development of epinecrotic (biofilms on Sus scrofa domesticus carcasses) and epilithic (biofilms on unglazed ceramic tiles) communities in two small streams using bacterial automated ribosomal intergenic spacer analysis. Epinecrotic communities were significantly different from epilithic communities even though environmental factors associated with each stream location also had a significant influence on biofilm structure. All communities at both locations exhibited significant succession suggesting that changing communities throughout time is a general characteristic of stream biofilm communities. The implications resulting from this work are that epinecrotic communities have distinctive shifts at the first and second weeks, and therefore the potential to be used in forensic applications by associating successional changes with submersion time to estimate a PMSI. The influence of environmental factors, however, indicates the lack of a successional pattern with the same organisms and a focus on functional diversity may be more applicable in a forensic context

    Sensory testing in leprosy:Comparison of ballpoint pen and monofilaments

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    The 10 g monofilament has been replaced by the ballpoint pen in routine sensory testing of nerves in leprosy control in Ethiopia. Results of sensory testing between the ballpoint pen and different monofilaments on hands and feet were compared. Ballpoint pen underdiagnosis of loss of sensation was defined to occur when the pen was felt and the monofilament was not. Differences were evaluated both for individual test points (test point level) and for the test points of extremities collectively (extremity level). An extremity (either a hand or a foot) was defined as having sensory nerve function impairment (SNFI) if a supplying nerve had SNFI, which was the case when sensation was absent in two or more test points in the area supplied by that nerve. At test point level, the percentages with ballpoint pen underdiagnosis relative to the 2, 10, 20 and 50 g monofilaments were 40, 21, 9 and 7%, respectively, in the hands, and 47, 30, 15 and 7% in the feet. Ballpoint pen underdiagnosis percentages of SNFI at extremity level were 32, 18, 8 and 9% in the hands, and 37, 26, 14 and 6% in the feet. The risk of ballpoint pen underdiagnosis appears to be higher in extremities without visible damage. In conclusion, substantial levels of underdiagnosis of sensory loss with the ballpoint pen were observed. However, the consequences for the prognosis of treatment with corticosteroids in patients with the more subtle sensation loss noted here need to be established. Development and testing of guidelines is a prerequisite for the use of the ballpoint pen
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