675 research outputs found
Mine Safety Detection System (MSDS)
Systems Engineering Project ReportThe search, detection, identification and assessment components of the U.S. Navys organic modular in-stride Mine Countermeasure (MCM) Concept of Operations (CONOPS) have been evaluated for their effectiveness as part of a hypothetical exercise in response to the existence of sea mines placed in the sea lanes of the Strait of Hormuz. The current MCM CONOPS has been shown to be capable of supporting the mine search and detection effort component allocation needs by utilizing two Airborne Mine Countermeasure (AMCM) deployed systems. This adequacy assessment is tenuous. The CONOPS relies heavily upon the Sikorsky MH- 60/S as the sole platform from which the systems operate. This reliance is further compounded by the fact both AMCM systems are not simultaneously compatible on board the MH-60/S. As such, resource availability will challenge the MCM CONOPS as well as the other missions for which the MH-60/S is intended. Additionally, the AMCM CONOPS systems are dependent upon the presence of warfighters in the helicopters above the minefield and as integral participants in the efforts to identify sea mines and to assess their threat level. Model Based System Engineering (MBSE) techniques have been combined with research and stakeholder inputs in an analysis that supports these assertions.mhttp://archive.org/details/minesafetydetect1094517457Approved for public release; distribution is unlimited
How genealogies are affected by the speed of evolution
In a series of recent works it has been shown that a class of simple models
of evolving populations under selection leads to genealogical trees whose
statistics are given by the Bolthausen-Sznitman coalescent rather than by the
well known Kingman coalescent in the case of neutral evolution. Here we show
that when conditioning the genealogies on the speed of evolution, one finds a
one parameter family of tree statistics which interpolates between the
Bolthausen-Sznitman and Kingman's coalescents. This interpolation can be
calculated explicitly for one specific version of the model, the exponential
model. Numerical simulations of another version of the model and a
phenomenological theory indicate that this one-parameter family of tree
statistics could be universal. We compare this tree structure with those
appearing in other contexts, in particular in the mean field theory of spin
glasses
Factors Associated with the Diversification of the Gut Microbial Communities within Chimpanzees from Gombe National Park.
The gastrointestinal tract harbors large and diverse populations of bacteria that vary among individuals and within individuals over time. Numerous internal and external factors can influence the contents of these microbial communities, including diet, geography, physiology, and the extent of contact among hosts. To investigate the contributions of such factors to the variation and changes in gut microbial communities, we analyzed the distal gut microbiota of individual chimpanzees from two communities in Gombe National Park, Tanzania. These samples, which were derived from 35 chimpanzees, many of whom have been monitored for multiple years, provide an unusually comprehensive longitudinal depth for individuals of known genetic relationships. Although the composition of the great-ape microbiota has been shown to codiversify with host species, indicating that host genetics and phylogeny have played a major role in its differentiation over evolutionary timescales, the geneaological relationships of individual chimpanzees did not coincide with the similarity in their gut microbial communities. However, the inhabitants from adjacent chimpanzee communities could be distinguished based on the contents of their gut microbiota. Despite the broad similarity of community members, as would be expected from shared diet or interactions, long-term immigrants to a community often harbored the most distinctive gut microbiota, suggesting that individuals retain hallmarks of their previous gut microbial communities for extended periods. This pattern was reinforced in several chimpanzees sampled over long temporal scales, in which the major constituents of the gut microbiota were maintained for nearly a decade
Living in a potentially toxic environment: comparisons of endofauna in two congeneric sponges from the Great Barrier Reef
© Inter-Research 2005The abundance and community composition of the endofauna in 2 species of sponge, Haliclona sp. 1 and Haliclona sp. 2 (phylum Porifera: order Haplosclerida), were examined at different sites on the slope at Heron Island Reef, in the southern Great Barrier Reef, on 2 separate occasions. Both species of Haliclona occupy similar habitats on the reef slope and are often found living adjacent to each other, but the major groups of secondary metabolites and the gross external morphology in the 2 species of sponge are different. The 2 species of sponge supported significantly different endofaunal communities, with Haliclona sp. 2 supporting 3 to 4 times more individuals than Haliclona sp. 1. Fewer demersal zooplankton (copepods), nematodes and some peracarid crustaceans were found in Haliclona sp. 1 compared with Haliclona sp. 2. There were also differences in the numbers of spionid, nereidid and syllid polychaetes living in the 2 species of sponge. The only taxon that was more abundant in Haliclona sp. 1 than Haliclona sp. 2 was the spionid Polydorella prolifera, and this difference was only evident on 1 of the 2 occasions. The amount of free space (pores, channels, cavities) for a given weight of sponge was only 19% greater in Haliclona sp. 2 than in Haliclona sp. 1, suggesting other factors, such as the differences in the allelochemicals, may have a role in determining the numbers and types of animals living in these 2 species of sponge.Greg A. Skilleter, Bayden D. Russell, Bernard M. Degnan, Mary J. Garso
Health care payments in the asia pacific: validation of five survey measures of economic burden
Introduction: Many low and middle-income countries rely on out-of-pocket payments to help finance health care. These payments can pose financial hardships for households; valid measurement of this type of economic burden is therefore critical. This study examines the validity of five survey measures of economic burden caused by health care payments. Methods: We analyzed 2002/03 World Health Survey household-level data from four Asia Pacific countries to assess the construct validity of five measures of economic burden due to health care payments: any health expenditure, health expenditure amount, catastrophic health expenditure, indebtedness, and impoverishment. We used generalized linear models to assess the correlations between these measures and other constructs with which they have expected associations, such as health care need, wealth, and risk protection. Results: Measures of impoverishment and indebtedness most often correlated with health care need, wealth, and risk protection as expected. Having any health expenditure, a large health expenditure, or even a catastrophic health expenditure did not consistently predict degree of economic burden. Conclusions: Studies that examine economic burden attributable to health care payments should include measures of impoverishment and indebtedness
A Comparison of Error Rates Between Intravenous Push Methods: A Prospective, Multisite, Observational Study
Objectives Current literature estimates the error rate associated with the preparation and administration of all intravenous (IV) medications to be 9.4% to 97.7% worldwide. This study aims to compare the number of observed medication preparation and administration errors between the only commercially available ready-to-administer product (Simplist) and IV push traditional practice, including a cartridge-based syringe system (Carpuject) and vials and syringes.
Methods A prospective, multisite, observational study was conducted in 3 health systems in various states within the United States between December 2015 and March 2016 to observe IV push medication preparation and administration. Researchers observed a ready-to-administer product and IV push traditional practice using a validated observational method and a modified data collection sheet. All observations were reconciled to the original medication order to determine if any errors occurred.
Results Researchers collected 329 observations (ready to administer = 102; traditional practice = 227) and observed 260 errors (ready to administer = 25; traditional practice = 235). The overall observed error rate for ready-to-administer products was 2.5%, and the observed error rate for IV push traditional practice was 10.4%.
Conclusions The ready-to-administer group demonstrated a statistically significant lower observed error rate, suggesting that use of this product is associated with fewer observed preparation and administration errors in the clinical setting. Future studies should be completed to determine the potential for patient harm associated with these errors and improve clinical practice because it relates to the safe administration of IV push medications
Iodoarene-Catalyzed Cyclizations of Unsaturated Amides
The cyclization of N-alkenylamides catalyzed by iodoarenes under oxidative conditions is presented. Five-, six-, and seven-membered rings with a range of substitutions can be prepared by this route. Preliminary data from the use of chiral iodoarenes as precatalysts show that enantiocontrol is feasible
An analytical upper bound on the number of loci required for all splits of a species tree to appear in a set of gene trees
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