3,396 research outputs found
An assessment of tailoring of lightning protection design requirements for a composite wing structure on a metallic aircraft
The Navy A-6E aircraft is presently being modified with a new wing which uses graphite/epoxy structures and substructures around a titanium load-bearing structure. The ability of composites to conduct electricity is less than that of aluminum. This is cause for concern when the wing may be required to conduct large lightning currents. The manufacturer attempted to solve lightning protection issues by performing a risk assessment based on a statistical approach which allows relaxation of the wing lightning protection design levels over certain locations of the composite wing. A sensitivity study is presented designed to define the total risk of relaxation of the design levels
The development of the Inspectorate of the committee of the council and the board of education from 1860 to 1920
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Embedding Population Dynamics Models in Inference
Increasing pressures on the environment are generating an ever-increasing
need to manage animal and plant populations sustainably, and to protect and
rebuild endangered populations. Effective management requires reliable
mathematical models, so that the effects of management action can be predicted,
and the uncertainty in these predictions quantified. These models must be able
to predict the response of populations to anthropogenic change, while handling
the major sources of uncertainty. We describe a simple ``building block''
approach to formulating discrete-time models. We show how to estimate the
parameters of such models from time series of data, and how to quantify
uncertainty in those estimates and in numbers of individuals of different types
in populations, using computer-intensive Bayesian methods. We also discuss
advantages and pitfalls of the approach, and give an example using the British
grey seal population.Comment: Published at http://dx.doi.org/10.1214/088342306000000673 in the
Statistical Science (http://www.imstat.org/sts/) by the Institute of
Mathematical Statistics (http://www.imstat.org
Dialkylcarbamoyl chloride (DACC)-coated dressings in the management and prevention of wound infection: A systematic review
Objective: Dialkylcarbomoyl chloride (DACC)-coated dressings (Leukomed Sorbact and Cutimed Sorbact) irreversibly bind bacteria at the wound surface that are then removed when the dressing is changed. They are a recent addition to the wound care professional's armamentarium and have been used in a variety of acute and chronic wounds. This systematic review aims to assess the evidence supporting the use of DACC-coated dressings in the clinical environment. Method: We included all reports of the clinical use of DACC-coated dressings in relation to wound infection. Medline, Embase, CENTRAL and CINAHL databases were searched to September 2016 for studies evaluating the role of DACC-coated dressings in preventing or managing wound infections. Results: We identified 17 studies with a total of 3408 patients which were included in this review. The DACC-coating was suggested to reduce postoperative surgical site infection rates and result in chronic wounds that subjectively looked cleaner and had less bacterial load on microbiological assessments. Conclusion: Existing evidence for DACC-coated dressings in managing chronic wounds or as a surgical site infection (SSI) prophylaxis is limited but encouraging with evidence in support of DACC-coated dressings preventing and treating infection without adverse effects
Modular construction provides large volume storage facility in minimum space
Each modular element consists of two hemispherical shells with material removed near their apexes to permit joining by a weldment to form a passage. Elements are welded together at their largest dimensions to form either a straight line continuous or a circular pressure vessel
Measurement of wire deflection on loading may indicate union in Ilizarov constructs, an in vitro model.
No entirely reliable method exists for assessing union during Ilizarov treatment. Premature removal results in potential treatment failure; hence, alternative methods warrant investigation. Wire deflection might provide an indication of fracture site deformation on weight bearing, indicating progress towards union. This study aimed to test a method for assessing wire deflection within an Ilizarov frame. (1) To assess the repeatability of our novel measurement method in measuring wire deflection within an Ilizarov frame in vitro. (2) To compare the amount of wire deflection in an unstable model with that in an intact bone model. (3) To assess accuracy of this method by comparing wire deflection measured with overall machine extension. Tests were performed on clinical grade-tensioned fine wire 4-ring Ilizarov constructs stabilising a simulated fracture, with and without an unstable defect. Models were sequentially loaded to 700 N using an Instron testing machine. A digital depth gauge attached to the superior ring measured relative wire displacement at the ring closest to the fracture. Tests were repeated 3 times. (1) Both unstable and stable bone models produced highly repeatable load deformation curves (R2 = 0.98 and 0.99). (2) In the unstable model, wires tensioned at 882 and 1274 N produced mean maximum deflections of 2.41 and 2.69 mm compared with 0.05 and 0.04 mm in the intact bone model (significant p < 0.0001). (3) Wire deflection and machine extension results were strongly correlated (r = 0.99). A measurable difference in wire deflection between stable and unstable situations exists using this method which appears accurate and repeatable, with clear correlation between displacement and load and displacement and machine extension. This approach might be clinically applicable, and further clinical testing is required
Toxin gene expression by shiga toxin-producing Escherichia coli: the role of antibiotics and the bacterial SOS response.
Toxin synthesis by Shiga toxin-producing Escherichia coli (STEC) appears to be coregulated through induction of the integrated bacteriophage that encodes the toxin gene. Phage production is linked to induction of the bacterial SOS response, a ubiquitous response to DNA damage. SOS-inducing antimicrobial agents, particularly the quinolones, trimethoprim, and furazolidone, were shown to induce toxin gene expression in studies of their effects on a reporter STEC strain carrying a chromosome-based stx2::lacZ transcriptional fusion. At antimicrobial levels above those required to inhibit bacterial replication, these agents are potent inducers (up to 140-fold) of the transcription of type 2 Shiga toxin genes (stx2); therefore, they should be avoided in treating patients with potential or confirmed STEC infections. Other agents (20 studied) and incubation conditions produced significant but less striking effects on stx2 transcription; positive and negative influences were observed. SOS-mediated induction of toxin synthesis also provides a mechanism that could exacerbate STEC infections and increase dissemination of stx genes. These features and the use of SOS-inducing antibiotics in clinical practice and animal husbandry may account for the recent emergence of STEC disease
Search and modelling of remnant radio galaxies in the LOFAR Lockman Hole field
Accepted for publication in Astronomy & Astrophysics. Reproduced with permission from Astronomy & Astrophysics, © 2017 ESO.The phase of radio galaxy evolution after the jets have switched off, often referred to as the remnant phase, is poorly understood and very few sources in this phase are known. In this work we present an extensive search for remnant radio galaxies in the Lockman Hole, a well-studied extragalactic field. We create mock catalogues of low-power radio galaxies based on Monte Carlo simulations to derive first-order predictions of the fraction of remnants in radio flux limited samples for comparison with our Lockman-Hole sample. We have combined LOFAR observations at 150 MHz with public surveys at higher frequencies to perform a complete selection and have used, for the first time, a combination of spectral criteria (e.g. the classical ultra-steep spectral index and high spectral curvature) as well as morphological criteria (e.g. low radio core prominence and relaxed shapes). Mock catalogues of radio galaxies are created based on existing spectral and dynamical evolution models combined with observed source properties. We have identified 23 candidate remnant radio galaxies which cover a variety of morphologies and spectral characteristics. We suggest that these different properties are related to different stages of the remnant evolution. We find that ultra-steep spectrum remnants represent only a fraction of our remnant sample suggesting a very rapid luminosity evolution of the radio plasma. Results from mock catalogues demonstrate the importance of dynamical evolution in the remnant phase of low-power radio galaxies to obtain fractions of remnant sources consistent with our observations. Moreover, these results confirm that ultra-steep spectrum remnants represent only a subset of the entire population (50%) when frequencies higher than 1400 MHz are not included in the selection process, and that they are biased towards old ages.Peer reviewe
An Evolutionary Method for the Minimum Toll Booth Problem: the Methodology
This paper considers the minimum toll booth problem (MINTB) for determining a tolling strategy in a transportation network that requires the least number of toll locations, and simultaneously causes the most efficient use of the network. The paper develops a methodology for using the genetic algorithm to solve MINTB and presents the algorithm GAMINTB. The proposed method is tested and validated through a computational study with six example networks. Additional numerical test discovers some interesting properties for the proposed method, and provides guidelines for further application of the GAMINTB
Light-induced changes in fatty acid profiles of specific lipid classes in several freshwater phytoplankton species
We tested the influence of two light intensities [40 and 300 µmol PAR / (m² s)] on the fatty acid composition of three distinct lipid classes in four freshwater phytoplankton species. We chose species of different taxonomic classes in order to detect potentially similar reaction characteristics that might also be present in natural phytoplankton communities. From samples of the bacillariophyte Asterionella formosa, the chrysophyte Chromulina sp., the cryptophyte Cryptomonas ovata and the zygnematophyte Cosmarium botrytis we first separated glycolipids (monogalactosyldiacylglycerol, digalactosyldiacylglycerol, and sulfoquinovosyldiacylglycerol), phospholipids (phosphatidylcholine, phosphatidylethanol-amine, phosphatidylglycerol, phosphatidylinositol, and phosphatidylserine) as well as non-polar lipids (triacylglycerols), before analyzing the fatty acid composition of each lipid class. High variation in the fatty acid composition existed among different species. Individual fatty acid compositions differed in their reaction to changing light intensities in the four species. Although no generalizations could be made for species across taxonomic classes, individual species showed clear but small responses in their ecologically-relevant omega-3 and omega-6 polyunsaturated fatty acids in terms of proportions and of per carbon quotas. Knowledge on how lipids like fatty acids change with environmental or culture conditions is of great interest in ecological food web studies, aquaculture and biotechnology, since algal lipids are the most important sources of omega-3 long-chain polyunsaturated fatty acids for aquatic and terrestrial consumers, including human
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