925 resultados para post-Newtonian approximation to general relativity
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Generalized KerrSchild space-times for a perfect-fluid source are investigated. New Petrov type D perfect fluid solutions are obtained starting from conformally flat perfect-fluid metrics.
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INTRODUCTION. Multimodal strategy targeted at prevention of catheter-related infection combine education to general measures of hygiene with specific guidelines for catheter insertion and dressing (1). OBJECTIVES. In this context, we tested the introduction of chlorhexidine(CHX)-impregnated sponges (2). METHODS. In our 32-beds mixed ICU, prospective surveillance of primary bacteremia and of microbiologically documented catheter-related bloodstream infections (CRBSI) is performed according to standardized definitions. New guidelines for central venous catheter (CVC) dressing combined a CHX-impregnated sponge (BioPatch_) with a transparent occlusive dressing (Tegaderm _) and planning for refection every 7 days. To contain costs, Biopatch_ was used only for internal jugular and femoral sites. Other elements of the prevention were not modified (overall compliance to hand hygiene 65-68%; non coated catheters except for burned patients [173 out of 9,542 patients];maximal sterile barriers for insertion; alcoholic solution ofCHXfor skin disinfection). RESULTS. Median monthly CVC-days increased from 710, to 749, 855 and 965 in 2006, 2007, 2008 and 2009, respectively (p\0.01). Following introduction of the new guidelines (4Q2007), the average monthly rate of infections decreased from 3.7 (95% CI: 2.6-4.8) episodes/1000 CVC-days over the 24 preceding months to 2.2 (95% CI: 1.5-2.8) over the 24 following months (p = 0.031). Dressings needed to be changed every 3-4 days. The decrease of catheter-related infections we observed in all consecutive admitted patients is comparable to that recently showed in a placeborandomized trial2. Further generalization to all CVC and arterial catheters access may be justified. CONCLUSIONS. Our data strongly suggest that combined with occlusive dressings, CHXimpregnated sponges for dressing of all CVC catheters inserted in internal jugular and/or femoral sites, significantly reduces the rate of primary bacteremia and CRBSI. REFERENCES. (1) Eggimann P, Harbarth S, Constantin MN, Touveneau S, Chevrolet JC, Pittet D. Impact of a prevention strategy targeted at vascular-access care on incidence of infections acquired in intensive care. Lancet 2000; 355:1864-1868. (2) Timsit JF, Schwebel C, Bouadma L, Geffroy A, Garrouste-Org, Pease S et al. Chlorhexidine- impregnated sponges and less frequent dressing changes for prevention of catheter-related infections in critically ill adults: a randomized controlled trial. JAMA 2009; 301(12):1231-1241.
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For the general practitioner to be able to prescribe optimal therapy to his individual hypertensive patients, he needs accurate information on the therapeutic agents he is going to administer and practical treatment strategies. The information on drugs and drug combinations has to be applicable to the treatment of individual patients and not just patient study groups. A basic requirement is knowledge of the dose-response relationship for each compound in order to choose the optimal therapeutic dose. Contrary to general assumption, this key information is difficult to obtain and often not available to the physician for many years after marketing of a drug. As a consequence, excessive doses are often used. Furthermore, the physician needs comparative data on the various antihypertensive drugs that are applicable to the treatment of individual patients. In order to minimize potential side effects due to unnecessary combinations of compounds, the strategy of sequential monotherapy is proposed, with the goal of treating as many patients as possible with monotherapy at optimal doses. More drug trials of a crossover design and more individualized analyses of the results are badly needed to provide the physician with information that he can use in his daily practice. In this time of continuous intensive development of new antihypertensive agents, much could be gained in enhanced efficacy and reduced incidence of side effects by taking a closer look at the drugs already available and using them more appropriately in individual patients.
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Following acute myocardial infarction, necrotic cardiac tissue is replaced by scar leading to ventricular remodeling and pump failure. Transplantation of autologous bone marrow-derived cells into the heart, early post-infarct, aims to prevent ventricular remodeling. This strategy has been evaluated in four controlled, randomized clinical trials, which provided mixed results. A transient improvement in ventricular function was observed in one trial, and a modest improvement (the duration of which remains to be determined) in an additional trial, whereas two trials showed negative results. A modest benefit of bone marrow cell transplantation was also observed in patients with chronic ischemic heart disease. Despite mixed results reported so far, cell therapy of heart disease still is in its infancy and has considerable room for improvement.
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This research project strives to help the Iowa Department of Transportation (DOT) fully achieve the full benefits of pavement preservation through training on proper selection, design, and application of pavement preservation treatments. In some cases, there is a lack of training when conducting one of these steps and the objective of applying pavement preservation techniques is compromised. Extensive amounts of literature on pavement preservation exist, but a structured approach on how to train staff in selecting, designing, and applying pavement preservation techniques is lacking. The objective of this project was to develop a training-oriented learning management system to address pavement preservation treatments (chip seals, fog seals, slurry systems, and crack seals and fills) as they are dealt with during the phases of selection, design, and construction. Early in the project, it was critical to identify the staff divisions to be trained and the treatments to be included. Through several meetings with the Iowa DOT, three staff divisions were identified: maintenance staff (in charge of selection), design staff, and construction staff. In addition, the treatments listed above were identified as the focus of the study due to their common use. Through needs analysis questionnaires and meetings, the knowledge gap and training needs of the agency were identified. The training modules developed target the gap from the results of the needs analysis. The concepting (selection) training focuses on providing the tools necessary to help make proper treatment selection. The design training focuses on providing the information necessary on the treatment materials (mostly binders and aggregates) and how to make proper material selection. Finally, the construction training focuses on providing equipment calibration procedures, inspection responsibilities, and images of poor and best practices. The research showed that it is important to train each division staff (maintenance, design, and construction) separately, as each staff division has its own needs and interests. It was also preferred that each treatment was covered on an individual basis. As a result of the research, it is recommended to evaluate the performance of pavement preservation treatments pre- and post-training continuously to compare results and verify the effectiveness of the learning management system.
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The unifying objective of Phases I and II of this study was to determine the feasibility of the post-tensioning strengthening method and to implement the technique on two composite bridges in Iowa. Following completion of these two phases, Phase III was undertaken and is documented in this report. The basic objectives of Phase III were further monitoring bridge behavior (both during and after post-tensioning) and developing a practical design methodology for designing the strengthening system under investigation. Specific objectives were: to develop strain and force transducers to facilitate the collection of field data; to investigate further the existence and effects of the end restraint on the post-tensioning process; to determine the amount of post-tensioning force loss that occurred during the time between the initial testing and the retesting of the existing bridges; to determine the significance of any temporary temperature-induced post-tensioning force change; and to develop a simplified design methodology that would incorporate various variables such as span length, angle-of-skew, beam spacing, and concrete strength. Experimental field results obtained during Phases II and III were compared to the theoretical results and to each other. Conclusions from this research are as follows: (1) Strengthening single-span composite bridges by post-tensioning is a viable, economical strengthening technique. (2) Behavior of both bridges was similar to the behavior observed from the bridges during field tests conducted under Phase II. (3) The strain transducers were very accurate at measuring mid-span strain. (4) The force transducers gave excellent results under laboratory conditions, but were found to be less effective when used in actual bridge tests. (5) Loss of post-tensioning force due to temperature effects in any particular steel beam post-tensioning tendon system were found to be small. (6) Loss of post-tensioning force over a two-year period was minimal. (7) Significant end restraint was measured in both bridges, caused primarily by reinforcing steel being continuous from the deck into the abutments. This end restraint reduced the effectiveness of the post-tensioning but also reduced midspan strains due to truck loadings. (8) The SAP IV finite element model is capable of accurately modeling the behavior of a post-tensioned bridge, if guardrails and end restraints are included in the model. (9) Post-tensioning distribution should be separated into distributions for the axial force and moment components of an eccentric post-tensioning force. (10) Skews of 45 deg or less have a minor influence on post-tensioning distribution. (11) For typical Iowa three-beam and four-beam composite bridges, simple regression-derived formulas for force and moment fractions can be used to estimate post-tensioning distribution at midspan. At other locations, a simple linear interpolation gives approximately correct results. (12) A simple analytical model can accurately estimate the flexural strength of an isolated post-tensioned composite beam.
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We present a combined shape and mechanical anisotropy evolution model for a two-phase inclusion-bearing rock subject to large deformation. A single elliptical inclusion embedded in a homogeneous but anisotropic matrix is used to represent a simplified shape evolution enforced on all inclusions. The mechanical anisotropy develops due to the alignment of elongated inclusions. The effective anisotropy is quantified using the differential effective medium (DEM) approach. The model can be run for any deformation path and an arbitrary viscosity ratio between the inclusion and host phase. We focus on the case of simple shear and weak inclusions. The shape evolution of the representative inclusion is largely insensitive to the anisotropy development and to parameter variations in the studied range. An initial hardening stage is observed up to a shear strain of gamma = 1 irrespective of the inclusion fraction. The hardening is followed by a softening stage related to the developing anisotropy and its progressive rotation toward the shear direction. The traction needed to maintain a constant shear rate exhibits a fivefold drop at gamma = 5 in the limiting case of an inviscid inclusion. Numerical simulations show that our analytical model provides a good approximation to the actual evolution of a two-phase inclusion-host composite. However, the inclusions develop complex sigmoidal shapes resulting in the formation of an S-C fabric. We attribute the observed drop in the effective normal viscosity to this structural development. We study the localization potential in a rock column bearing varying fraction of inclusions. In the inviscid inclusion case, a strain jump from gamma = 3 to gamma = 100 is observed for a change of the inclusion fraction from 20% to 33%.
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Purpose: Aqueous flow through trabeculectomy blebs has been suggested to influence filtration bleb survival. We investigated the relationship between the requirement to increase aqueous flow via adjustable suture removal and surgical outcomes following "safe trabeculectomy" with mitomycin C (MMC). Methods: 62 consecutive eyes of 53 patients underwent fornix based trabeculectomy with adjustable sutures, intraoperative MMC and intensive postoperative steroids. Subconjunctival antimetabolite injections and bleb needlings were administered according to bleb vascularity and IOP trends. Main outcome measures were: success rates (definition: IOP≤21mmHg and 20% IOP reduction); number of antimetabolite injections; bleb needlings; number of of eyes recommencing glaucoma medications and complications. Results: Mean age was 70.4±16.0 years (mean± SD); mean preoperative IOP was 24.5±9.1 mmHg and decreased to 12.3±8.9mmHg postoperatively. Mean number of sutures was 2.6 ± 0.7. Eyes were divided into 2 groups in relation to the number of sutures removed. The number of subconjunctival MMC injections required for those requiring 2 suture removals was significantly greater than those requiring 1 suture removal (p<0.05) The number of needlings and 5FU injections also increased but did not reach significance (p=0.09 and p=0.34 respectively). Least-squared linear regression analysis showed the number of needlings required had a statistically significant (p=0.05) trend with respect to time elapsed between surgery and first suture removal. No other interventions had significant trends. Mean time between surgery and suture removal was: 4.2±9.2 weeks (suture #1) and 5.7±9.7 weeks (suture#2). Antiglaucoma medication was restarted in only 5 eyes. Postoperative complications were infrequent: Seidel (3.2%), peripheral choroidal effusions at any time (3.2%), and shallow anterior chamber (1.6%). Conclusion: Eyes requiring a greater number of suture removals required a significantly greater number of antifibrosis interventions. The time elapsed before suture removal was inversely related to the number of postoperative needlings, suggesting these eyes may have decreased aqueous production and therefore require aggressive post-operative management to prevent bleb failure.
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OBJECTIVES: In 2002, the canton of Fribourg, Switzerland, implemented a coordinated pharmaceutical care service in nursing homes to promote rational drug use. In the context of this service, a project was conducted to develop recommendations for the pharmacological management of behavioral and psychological symptoms of dementia (BPSD) in nursing home residents. DESIGN AND METHODS: Selected evidence-based guidelines and meta-analysis sources related to the management of depression, insomnia, and agitation in dementia patients were systematically searched and evaluated. Evidence and controversies regarding the pharmacological treatment of the most common BPSD symptoms were reviewed, and treatment algorithms were developed. RESULTS: Ten evidence-based guidelines and meta-analyses for BPSD management were identified, with none specifically addressing issues related to nursing home residents. Based on this literature, recommendations were developed for the practice of pharmacological management of depression, sleep disturbances, and agitation in nursing home residents. For depression, SSRIs are considered the first choice if an antidepressant is required. No clear evidence has been found for sleep disturbances; the underlying conditions need to be investigated closely before the introduction of any drug therapy. Many drugs have been investigated for the treatment of agitation, and if necessary, antipsychotics could be used, although they have significant side effects. Several areas of uncertainty were identified, such as the current controversy about typical and atypical antipsychotic use or the appropriateness of cholinesterase inhibitors for controlling agitation. Treatment algorithms were presented to general practitioners, pharmacists, and medical directors of nursing homes in the canton of Fribourg, and will now be implemented progressively, using educational sessions, pharmaceutical counseling, and monitoring. CONCLUSION: Based on existing evidence-based studies, recommendations were developed for the practice of pharmacological management of depression, sleep disturbances, and agitation in nursing home residents. It should be further studied whether these algorithms implemented through pharmaceutical care services will improve psychotropic drug prescriptions and prevent drug-related problems in nursing home residents
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PURPOSE OF THE STUDY: This prospective study reports our preliminary results with local anaesthesia (LA) for carotid endarterectomy (CEA). MATERIAL AND METHODS: Twenty CEA in nineteen patients were performed using a three-stage local infiltration technique. CEA were performed through a short Duplex-assisted skin incision (median length: 55 mm) using a retro-jugular approach and polyurethane patch closure (median length: 35 mm). RESULTS: There were 13 men and 6 women with a mean age of 71.2 years. The indications of CEA were asymptomatic lesions in 11 cases, stroke in 7 cases and transient ischaemic attack in 2 cases. The median degree of internal carotid artery stenosis was 90%. One patient (5%) required an intraluminal shunt. There were no peri-operative deaths, stroke or conversion to general anaesthesia (GA). The median length of stay was 3 days. CONCLUSIONS: LA is a good alternative to GA. It can be used after a feasibility study and a short teaching procedure. In our centre, it is a safe and effective procedure associated with low morbidity, high acceptance by patients and a short hospital stay.
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Mediante programa informático es posible simular las vías de comunicación existentes entre asentamientos humanos, siendo muchos los trabajos publicados y varias las formas de aproximación al problema. El objetivo del trabajo que nos ocupa ha consistido en la generación de un nuevo modelo a partir del cual fuera posible simular una vía de comunicación, con la salvedad de que en este caso ya existía una idea aproximada de cual sería su trayectoria a partir de trabajos de otros autores. Esta vía de comunicación es la vía Augusta, en el tramo que une el Coll de Panissars y la ciudad de Girona.
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A role for gut hormone in bone physiology has been suspected. We evidenced alterations of microstructural morphology (trabecular and cortical) and bone strength (both at the whole-bone - and tissue-level) in double incretin receptor knock-out (DIRKO) mice as compared to wild-type littermates. These results support a role for gut hormones in bone physiology. INTRODUCTION: The two incretins, glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1), have been shown to control bone remodeling and strength. However, lessons from single incretin receptor knock-out mice highlighted a compensatory mechanism induced by elevated sensitivity to the other gut hormone. As such, it is unclear whether the bone alterations observed in GIP or GLP-1 receptor deficient animals resulted from the lack of a functional gut hormone receptor, or by higher sensitivity for the other gut hormone. The aims of the present study were to investigate the bone microstructural morphology, as well as bone tissue properties, in double incretin receptor knock-out (DIRKO) mice. METHODS: Twenty-six-week-old DIRKO mice were age- and sex-matched with wild-type (WT) littermates. Bone microstructural morphology was assessed at the femur by microCT and quantitative X-ray imaging, while tissue properties were investigated by quantitative backscattered electron imaging and Fourier-transformed infrared microscopy. Bone mechanical response was assessed at the whole-bone- and tissue-level by 3-point bending and nanoindentation, respectively. RESULTS: As compared to WT animals, DIRKO mice presented significant augmentations in trabecular bone mass and trabecular number whereas bone outer diameter, cortical thickness, and cortical area were reduced. At the whole-bone-level, yield stress, ultimate stress, and post-yield work to fracture were significantly reduced in DIRKO animals. At the tissue-level, only collagen maturity was reduced by 9 % in DIRKO mice leading to reductions in maximum load, hardness, and dissipated energy. CONCLUSIONS: This study demonstrated the critical role of gut hormones in controlling bone microstructural morphology and tissue properties.
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We carried out a systematic review of HPV vaccine pre- and post-licensure trials to assess the evidence of their effectiveness and safety. We find that HPV vaccine clinical trials design, and data interpretation of both efficacy and safety outcomes, were largely inadequate. Additionally, we note evidence of selective reporting of results from clinical trials (i.e., exclusion of vaccine efficacy figures related to study subgroups in which efficacy might be lower or even negative from peer-reviewed publications). Given this, the widespread optimism regarding HPV vaccines long-term benefits appears to rest on a number of unproven assumptions (or such which are at odd with factual evidence) and significant misinterpretation of available data. For example, the claim that HPV vaccination will result in approximately 70% reduction of cervical cancers is made despite the fact that the clinical trials data have not demonstrated to date that the vaccines have actually prevented a single case of cervical cancer (let alone cervical cancer death), nor that the current overly optimistic surrogate marker-based extrapolations are justified. Likewise, the notion that HPV vaccines have an impressive safety profile is only supported by highly flawed design of safety trials and is contrary to accumulating evidence from vaccine safety surveillance databases and case reports which continue to link HPV vaccination to serious adverse outcomes (including death and permanent disabilities). We thus conclude that further reduction of cervical cancers might be best achieved by optimizing cervical screening (which carries no such risks) and targeting other factors of the disease rather than by the reliance on vaccines with questionable efficacy and safety profiles.
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Fabry disease (FD) is an X-linked lysosomal storage disorder caused by deficiency of alpha-galactosidase A, which leads to storage of sphingolipids in virtually all human cells and consequently to organ dysfunction. Pulmonary involvement is still debated. But, obstructive lung disease is up to ten times more prevalent in patients with FD compared to general public. Also, an accelerated decline in forced expiratory volume in one second (FEV1) over time was observed in these patients. Lysosomal storage of glycosphingolipids is considered leading to small airway disease via hyperplasia of the bronchiolar smooth muscle cells. Larger airways may become involved with ongoing disease process. There is no evidence for involvement of the lung interstitium in FD. The effect of enzyme replacement therapy on respiratory involvement remains to be determined in large, prospective controlled trials.
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PURPOSE: To evaluate the feasibility, efficacy, and tolerance of self-expanding metallic stent insertion under fluoroscopic guidance for palliation of symptoms related to malignant gastroduodenal obstruction. MATERIALS AND METHODS: Seventy-two patients (38 men, 34 women) aged 25-98 years (mean, 62 years) with duodenal (n = 43), antropyloric (n = 13), surgical gastrojejunostomy (n = 10), or pyloroduodenal (n = 6) malignant obstruction were referred for insertion of self-expanding metallic stents over a 6-year period. Stent insertion was performed with use of a peroral or transgastric approach when necessary (n = 11). RESULTS: Stents were successfully inserted in 70 of the 72 patients (97%) and provided symptom relief in 65 patients (90%). Inserted stents were mainly uncovered vascular (n = 55) or enteral (n = 10) Wallstents. One hundred eight stents were initially inserted: one, two, three, or four stents were indicated in 43, 17, nine, and one patient, respectively. Mean follow-up was 119 days (range, 4-513 days). Mean stent patency was 113 days (range, 4-513 days). Mean survival of patients was 120 days. During follow-up, stent obstruction occurred in seven patients as a result of tumoral overgrowth (n = 5) or ingrowth (n = 2). Complications occurred in 12 of the 72 patients (17%), including stent migration (n = 8), stent fracture (n = 1), duodenal perforation (n = 1), and death related to general anesthesia (n = 1). CONCLUSION: Despite a significant complication rate, self-expanding metallic stent insertion under fluoroscopic guidance appears to be a feasible and useful technique in the palliative management of malignant gastroduodenal obstruction.