1,516 research outputs found
A 0-D electric gun model for the optimization of flyer acceleration to hypervelocities
The electric gun is a pulsed power projectile launcher that utilizes the rapid expansion of an ohmically heated exploding foil and electromagnetic (EM) forces to accelerate thin flyers up to 20 km/s. Though the launcher has high energetic efficiencies when compared to alternative techniques, the process of launching flyers above 0.5 mm thickness in this manner often results in uncontrolled launch characteristics and premature failure of the flyer. This behavior is challenging to model numerically, limiting optimization work to sophisticated and computationally intensive magneto-hydrodynamics (MHD) codes. This work presents a 0-D model designed to expedite the parametric optimization process of electric gun loads to launch thick flyers to hypervelocities. The model is capable of predicting not only the foil state and flyer dynamics, but uses a novel approximation to predict the maximum pressure state in the flyer. The model is verified against 3-D MHD Eulerian hydrocode 'Code B' and the validity of the approximations made in simplifying the model are discussed. With this model, the electric gun could be optimized to launch thicker flyers and achieve higher pressures and shock durations, enabling it to become a complimentary tool to existing projectile launch platforms
Congenital syphilis, still a reality in 21st century: a case report
Congenital syphilis is a preventable disease and its presence reflects a failure of prenatal care delivery systems, as well as syphilis control programmes. The procedure to prevent congenital syphilis through antenatal screening and treatment is well established. But implementation of effective programmes has proved very difficult especially in resource constrained countries
Secondary user relations in emerging mobile computing environments
Mobile technologies are enabling access to information in diverse environ.ments, and are exposing a wider group of individuals to said technology. Therefore, this paper proposes that a wider view of user relations than is usually considered in information systems research is required. Specifically, we examine the potential effects of emerging mobile technologies on end-Ââuser relations with a focus on the âsecondary userâ, those who are not intended to interact directly with the technology but are intended consumers of the technologyâs output. For illustration, we draw on a study of a U.K. regional Fire and Rescue Service and deconstruct mobile technology use at Fire Service incidents. Our findings provide insights, which suggest that, because of the nature of mobile technologies and their context of use, secondary user relations in such emerging mobile environments are important and need further exploration
Understanding innovators' experiences of barriers and facilitators in implementation and diffusion of healthcare service innovations: A qualitative study
This article is made available through the Brunel Open Access Publishing Fund - Copyright @ 2011 Barnett et al.Background: Healthcare service innovations are considered to play a pivotal role in improving organisational efficiency and responding effectively to healthcare needs. Nevertheless, healthcare organisations encounter major difficulties in sustaining and diffusing innovations, especially those which concern the organisation and delivery of healthcare services. The purpose of the present study was to explore how healthcare innovators of process-based initiatives perceived and made sense of factors that either facilitated or obstructed the innovation implementation and diffusion. Methods: A qualitative study was designed. Fifteen primary and secondary healthcare organisations in the UK, which had received health service awards for successfully generating and implementing service innovations, were studied. In-depth, semi structured interviews were conducted with the organisational representatives who conceived and led the development process. The data were recorded, transcribed and thematically analysed. Results: Four main themes were identified in the analysis of the data: the role of evidence, the function of inter-organisational partnerships, the influence of human-based resources, and the impact of contextual factors. "Hard" evidence operated as a proof of effectiveness, a means of dissemination and a pre-requisite for the initiation of innovation. Inter-organisational partnerships and people-based resources, such as champions, were considered an integral part of the process of developing, establishing and diffusing the innovations. Finally, contextual influences, both intra-organisational and extra-organisational were seen as critical in either impeding or facilitating innovators' efforts. Conclusions: A range of factors of different combinations and co-occurrence were pointed out by the innovators as they were reflecting on their experiences of implementing, stabilising and diffusing novel service initiatives. Even though the innovations studied were of various contents and originated from diverse organisational contexts, innovators' accounts converged to the significant role of the evidential base of success, the inter-personal and inter-organisational networks, and the inner and outer context. The innovators, operating themselves as important champions and being often willing to lead constructive efforts of implementation to different contexts, can contribute to the promulgation and spread of the novelties significantly.This research was supported financially by the Multidisciplinary Assessment of
Technology Centre for Healthcare (MATCH)
Do Physicians Underrecognize Obesity?
Objectives: A physician's advice is among the strongest predictors of efforts toward weight management made by obese patients, yet only a minority receives such advice. One contributor could be the physician's failure to recognize true obesity. The objectives of this study were to assess physicians' ability to recognize obesity and to identify factors associated with recognition and documentation of obesity. Methods: Internal medicine residents and attending physicians at three academic urban primary care clinics and their adult patients participated in a study using recognition and documentation of patient obesity as the main measures. Results: A total of 52 physicians completed weight assessments for 400 patients. The mean patient age was 51 years, 56% were women, 77% were Hispanic, and 67% had one or more obesity-related comorbidity. There were 192 (48%) patients, of whom 66% were correctly identified by physicians as being obese, 86% of those with a body mass index (BMI) Q35, but only 49% of those with a BMI of 30 to 34.9 (P G 0.0001). Fewer obese Hispanic patients were identified than were non-Hispanic patients (62% vs 76%; P = 0.03). No physician characteristics were significantly associated with recognition of obesity. Physicians documented obesity as a problem for 51% of patients. Attending physicians documented obesity more frequently than did residents (64% vs 43%, odds ratio 2.5, 95% confidence interval 1.3Y4.6) and normal-weight physicians documented obesity more frequently than overweight physicians (58% vs 41%, odds ratio 2.0, 95% confidence interval 1.0Y4.0). Documentation was more common for patients with a BMI Q35 and for non-Hispanics. Documentation was not more common for patients with obesity-related comorbidities. Conclusions: Physicians have difficulty recognizing obesity unless patients' BMI is Q35. Training physicians to recognize true obesity may increase rates of documentation, a first step toward treatment
Rearrangement processes and structural variations show evidence of selection in oesophageal adenocarcinomas
Oesophageal adenocarcinoma (OAC) provides an ideal case study to characterize large-scale rearrangements. Using whole genome short-read sequencing of 383 cases, for which 214 had matched whole transcriptomes, we observed structural variations (SV) with a predominance of deletions, tandem duplications and inter-chromosome junctions that could be identified as LINE-1 mobile element (ME) insertions. Complex clusters of rearrangements resembling breakage-fusion-bridge cycles or extrachromosomal circular DNA accounted for 22% of complex SVs affecting known oncogenes. Counting SV events affecting known driver genes substantially increased the recurrence rates of these drivers. After excluding fragile sites, we identified 51 candidate new drivers in genomic regions disrupted by SVs, including ETV5, KAT6B and CLTC. RUNX1 was the most recurrently altered gene (24%), with many deletions inactivating the RUNT domain but preserved the reading frame, suggesting an altered protein product. These findings underscore the importance of identification of SV events in OAC with implications for targeted therapies
Asthma
Asthma is the most common respiratory disorder in Canada. Despite significant improvement in the diagnosis and management of this disorder, the majority of Canadians with asthma remain poorly controlled. In most patients, however, control can be achieved through the use of avoidance measures and appropriate pharmacological interventions. Inhaled corticosteroids (ICSs) represent the standard of care for the majority of patients. Combination ICS/long-acting beta2-agonists (LABA) inhalers are preferred for most adults who fail to achieve control with ICS therapy. Allergen-specific immunotherapy represents a potentially disease-modifying therapy for many patients with asthma, but should only be prescribed by physicians with appropriate training in allergy. Regular monitoring of asthma control, adherence to therapy and inhaler technique are also essential components of asthma management. This article provides a review of current literature and guidelines for the appropriate diagnosis and management of asthma
Following the sand grains
When longshore transport systems encounter tidal inlets, complex mechanisms are involved in bypassing sand to downdrift barriers. Here, this process is examined at Plum Island Sound and Essex Inlets, Massachusetts, USA. One major finding from this study is that sand is transferred along the coastâespecially at tidal inletsâby parcels, in discrete steps, and over decadal-scale periods. The southerly orientation of the main-ebb channel at Plum Island Sound, coupled with the landward migration of bars from the ebb delta to the central portion of the downdrift Castle Neck barrier island, have formed a beach protuberance. During the constructional phase, sand is sequestered at the protuberance and the spit-end of the barrier becomes sediment starved, leading to shoreline retreat and a broadening of the spit platform at the mouth to Essex Bay (downdrift side of Castle Neck). Storm-induced sand transport from erosion of the spit and across the spit platform is washed into Essex Bay, filling channels and enlarging flood deltas. This study illustrates the pathways and processes of sand transfer along the shoreline of a barrier-island/tidal-inlet system and provides an important example of the processes that future hydrodynamic and sediment-transport modeling should strive to replicate.Published versio
Gene expression and matrix turnover in overused and damaged tendons
Chronic, painful conditions affecting tendons, frequently known as tendinopathy, are very common types of sporting injury. The tendon extracellular matrix is substantially altered in tendinopathy, and these changes are thought to precede and underlie the clinical condition. The tendon cell response to repeated minor injuries or âoveruseâ is thought to be a major factor in the development of tendinopathy. Changes in matrix turnover may also be effected by the cellular response to physical load, altering the balance of matrix turnover and changing the structure and composition of the tendon. Matrix turnover is relatively high in tendons exposed to high mechanical demands, such as the supraspinatus and Achilles, and this is thought to represent either a repair or tissue maintenance function. Metalloproteinases are a large family of enzymes capable of degrading all of the tendon matrix components, and these are thought to play a major role in the degradation of matrix during development, adaptation and repair. It is proposed that some metalloproteinase enzymes are required for the health of the tendon, and others may be damaging, leading to degeneration of the tissue. Further research is required to investigate how these enzyme activities are regulated in tendon and altered in tendinopathy. A profile of all the metalloproteinases expressed and active in healthy and degenerate tendon is required and may lead to the development of new drug therapies for these common and debilitating sports injuries
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