866 research outputs found

    Generalized boundary-value problems

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    Potential Long-Term Complications of Endovascular Stent Grafting for Blunt Thoracic Aortic Injury

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    Blunt thoracic aortic injury (BTAI) is a rare, but lethal, consequence of rapid deceleration events. Most victims of BTAI die at the scene of the accident. Of those who arrive to the hospital alive, expedient aortic intervention significantly improves survival. Thoracic endovascular aortic repair (TEVAR) has been accepted as the standard of care for BTAI at many centers, primarily due to the convincing evidence of lower mortality and morbidity in comparison to open surgery. However, less attention has been given to potential long-term complications of TEVAR for BTAI. This paper focuses on these complications, which include progressive aortic expansion with aging, inadequate stent graft characteristics, device durability concerns, long-term radiation exposure concerns from follow-up computed tomography scans, and the potential for (Victims of Modern Imaging Technology) VOMIT

    Interspinous Spacer Implant in Patients with Lumbar Spinal Stenosis: Preliminary Results of a Multicenter, Randomized, Controlled Trial

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    A prospective, randomized, controlled trial was conducted to compare clinical outcomes in patients treated with an investigational interspinous spacer (Superion) versus those treated with an FDA-approved spacer (X-STOP). One hundred sixty-six patients with moderate lumbar spinal stenosis (LSS) unresponsive to conservative care were treated randomly with the Superion (n = 80) or X-STOP (n = 86) interspinous spacer. Study subjects were followed through 6 months posttreatment. Zurich Claudication Questionnaire (ZCQ) symptom severity scores improved 30% with Superion and 25% with X-STOP (both P < 0.001). Similar changes were noted in ZCQ physical function with improvements of 32% with Superion and 27% with X-STOP (both P < 0.001). Mean ZCQ patient satisfaction score ranged from 1.7 to 2.0 in both groups at all follow-up visits. The proportion of subjects that achieved at least two of three ZCQ clinical success criteria at 6 months was 75% with Superion and 67% with X-STOP. Axial pain decreased from 55 ± 27 mm at pretreatment to 22 ± 26 mm at 6 months in the Superion group (P < 0.001) and from 54 ± 29 mm to 32 ± 31 mm with X-STOP (P < 0.001). Extremity pain decreased from 61 ± 26 mm at pretreatment to 18 ± 27 mm at 6 months in the Superion group (P < 0.001) and from 64 ± 26 mm to 22 ± 30 mm with X-STOP (P < 0.001). Back function improved from 38 ± 13% to 21 ± 19% with Superion (P < 0.001) and from 40 ± 13% to 25 ± 16% with X-STOP (P < 0.001). Preliminary results suggest that the Superion interspinous spacer and the X-STOP each effectively alleviate pain and improve back function in patients with moderate LSS who are unresponsive to conservative care

    Observations on the Mating Behavior of Captive Spotted Sand Bass (Paralabrax maculatofasciatus)

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    The sex allocation pattern of various populations of spotted sand bass are thought to vary from functional gonochorism to strict protogyny. The development of hypotheses explaining how such a plastic (flexible) strategy has been maintained selectively has been hindered by a general lack of information on reproductive behavior in this species. Therefore, the spawning behavior of adult, wild-caught spotted sand bass were observed in captivity under a variety of densities. Three distinct spawning modes were observed: 1) pair spawning, 2) group spawning, and 3) spawning including a sneaker male. Courtship was characterized by the following sequence: 1) a male or males approach the females, 2) one or more males make contact with the ventro-lateral surface of the female and chase the female, 3) the male contacts the ventro-lateral surface of the female and pushes her through a vertical spawning rush. Spawning behavior involved ephemeral color changes, persistent physical contact initiated by the male, short rushes beginning near structure and ending in a vertical rush with a gamete release. In general, in low density groups, reproductive activity was dominated by a single male that actively excluded smaller males from spawning. The dominant male in these groups exclusively engaged in pair spawning. Individuals in groups of higher density spawned in groups, with no observations of large males monopolizing females. These observations are consistent with the predictions of the size-advantage hypothesis regarding mating strategies in fishes. We propose that these three spawning modes and the frequency with which they occur allow the flexibility seen in the mating strategies of isolated populations of spotted sand bass

    Facet-sparing lumbar decompression with a minimally invasive flexible MicroBlade Shaver® versus traditional decompression: quantitative radiographic assessment.

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    BackgroundLaminectomy/laminotomy and foraminotomy are well established surgical techniques for treatment of symptomatic lumbar spinal stenosis. However, these procedures have significant limitations, including limited access to lateral and foraminal compression and postoperative instability. The purpose of this cadaver study was to compare bone, ligament, and soft tissue morphology following lumbar decompression using a minimally invasive MicroBlade Shaver® instrument versus hemilaminotomy with foraminotomy (HL).MethodsThe iO-Flex® system utilizes a flexible over-the-wire MicroBlade Shaver instrument designed for facet-sparing, minimally invasive "inside-out" decompression of the lumbar spine. Unilateral decompression was performed at 36 levels in nine human cadaver specimens, six with age-appropriate degenerative changes and three with radiographically confirmed multilevel stenosis. The iO-Flex system was utilized on alternating sides from L2/3 to L5/S1, and HL was performed on the opposite side at each level by the same investigator. Spinal canal, facet joint, lateral recess, and foraminal morphology were assessed using computed tomography.ResultsSimilar increases in soft tissue canal area and decreases in ligamentum flavum area were noted in nondiseased specimens, although HL required removal of 83% more laminar area (P &lt; 0.01) and 95% more bone resection, including the pars interarticularis and facet joints (P &lt; 0.001), compared with the iO-Flex system. Similar increases in lateral recess diameter were noted in nondiseased specimens using each procedure. In stenotic specimens, the increase in lateral recess diameter was significantly (P = 0.02) greater following use of the iO-Flex system (43%) versus HL (7%). The iO-Flex system resulted in greater facet joint preservation in nondiseased and stenotic specimens. In stenotic specimens, the iO-Flex system resulted in a significantly greater increase in foraminal width compared with HL (24% versus 4%, P = 0.01), with facet joint preservation.ConclusionThe iO-Flex system resulted in significantly better decompression of the lateral recess and foraminal areas compared with HL, while preserving posterior spinal elements, including the facet joint

    Clinical utility of ultrasound guidance for intra-articular knee injections: a review

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    Intra-articular corticosteroid and hyaluronic acid injections provide short-term symptom amelioration for arthritic conditions involving structural damage or degenerative changes in the knee. Conventional palpation-guided anatomical injections frequently result in inaccurate needle placement into extra-articular tissue and adjacent structures. The purpose of this review was to determine the effect of ultrasound guidance on the accuracy of needle placement, clinical outcomes, and cost-effectiveness in comparison with anatomical landmark-guided intra-articular large joint injections, with particular emphasis on the knee. A total of 13 relevant studies were identified; five studied the knee, seven studied the shoulder, one used both the knee and shoulder, and none studied the hip. Ultrasound was used in seven studies; the remaining studies utilized air arthrography, fluoroscopy, magnetic resonance arthrography, or magnetic resonance imaging. Across all studies (using all imaging modalities and all joints), needle placement accuracy ranged from 63% to 100% with ultrasound and from 39% to 100% with conventional anatomical guidance. Imaging guidance improved the accuracy of intra-articular injections of the knee (96.7% versus 81.0%, P < 0.001) and shoulder (97.3% versus 65.4%, P < 0.001). In particular, ultrasound guidance of knee injections resulted in better accuracy than anatomical guidance (95.8% versus 77.8%, P < 0.001), yielding an odds ratio of 6.4 (95% confidence interval 2.9–14). Ultrasound guidance notably improves injection accuracy in the target intra-articular joint space of large joints including the knee. The enhanced injection accuracy achieved with ultrasound needle guidance directly improves patient-reported clinical outcomes and cost-effectiveness

    Percutaneous pedicle screw reduction and axial presacral lumbar interbody fusion for treatment of lumbosacral spondylolisthesis: A case series

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    <p>Abstract</p> <p>Introduction</p> <p>Traditional surgical management of lumbosacral spondylolisthesis is technically challenging and is associated with significant complications. The advent of minimally invasive surgical techniques offers patients treatment alternatives with lower operative morbidity risk. The combination of percutaneous pedicle screw reduction and an axial presacral approach for lumbosacral discectomy and fusion offers an alternative procedure for the surgical management of low-grade lumbosacral spondylolisthesis.</p> <p>Case presentation</p> <p>Three patients who had L5-S1 grade 2 spondylolisthesis and who presented with axial pain and lumbar radiculopathy were treated with a minimally invasive surgical technique. The patients-a 51-year-old woman and two men (ages 46 and 50)-were Caucasian. Under fluoroscopic guidance, spondylolisthesis was reduced with a percutaneous pedicle screw system, resulting in interspace distraction. Then, an axial presacral approach with the AxiaLIF System (TranS1, Inc., Wilmington, NC, USA) was used to perform the discectomy and anterior fixation. Once the axial rod was engaged in the L5 vertebral body, further distraction of the spinal interspace was made possible by partially loosening the pedicle screw caps, advancing the AxiaLIF rod to its final position in the vertebrae, and retightening the screw caps. The operative time ranged from 173 to 323 minutes, and blood loss was minimal (50 mL). Indirect foraminal decompression and adequate fixation were achieved in all cases. All patients were ambulatory after surgery and reported relief from pain and resolution of radicular symptoms. No perioperative complications were reported, and patients were discharged in two to three days. Fusion was demonstrated radiographically in all patients at one-year follow-up.</p> <p>Conclusions</p> <p>Percutaneous pedicle screw reduction combined with axial presacral lumbar interbody fusion offers a promising and minimally invasive alternative for the management of lumbosacral spondylolisthesis.</p

    Factors Influencing African American Youths\u27 Decisions to Stay in School

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    Little attention has been given to the non-problematic development and positive life decisions of African American youth. This paper reports findings of 231 African American students. The goal of the study was to assess factors which contribute to their academic grade point averages and intentions to stay in school. The conceptual model employed in this study was the Theory of Planned Behavior (TPB) which contends that intentions to carryout a behavior is a function of Attitude towards the behavior, Social Normative support for undertaking the behavior, and the Perceived Control of being able to carry out the behavior. In addition to the TPB components, the contributions of self-esteem and racial self-esteem were also examined for their influence on academic strivings. The TPB model did predict well student’s intentions to stay in school, but predicted less well student grade point averages. Self-esteem was also a significant predictor of intentions to stay in school, but was not a significant predictor of gpa. Racial self-esteem was observed to be only marginally significant, but as predicted, was negatively associated with student Intentions to stay in school. However racial self esteem was not observed to be a significant predictor of student gpa. Hence students with positive self-esteem, who have favorable attitudes towards school and perceive fewer barriers to completing school are most likely to do so. But, the negative association between racial self-esteem and academic intentions suggests that some African American youths may need be convinced that academic success is not an act of racial betrayal

    A detailed seabed signature from Hurricane Sandy revealed in bedforms and scour

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    On 30 October 2012, Hurricane Sandy made landfall near Brigantine New Jersey bringing widespread erosion and damage to the coastline. We have obtained a unique set of high-resolution before and after storm measurements of seabed morphology and in situhydrodynamic conditions (waves and currents) capturing the impact of the storm at an inner continental shelf field site known as the “Redbird reef”. Understanding the signature of this storm event is important for identifying the impacts of such events and for understanding the role that such events have in the transport of sediment and marine debris on the inner continental shelf. As part of an ONR-sponsored program designed to understand and characterize the ripple dynamics and scour processes in an energetic, heterogeneous inner-shelf setting, a series of high-resolution geoacoustic surveys were conducted before and after Hurricane Sandy. Our overall goal is to improve our understanding of bedform dynamics and spatio-temporal length scales and defect densities through the application of a recently developed fingerprint algorithm technique. Utilizing high-resolution swath sonar collected by an AUV and from surface vessel sonars, our study focuses both on bedforms in the vicinity of manmade seabed objects and dynamic natural ripples on the inner shelf in energetic coastal settings with application to critical military operations such as mine countermeasures
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