4,027 research outputs found

    Francis Daniels Moore: one of the brightest minds in the surgical field.

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    Francis Daniels Moore was a pioneer ahead of his time who made numerous landmark contributions to the field of surgery, including the understanding of metabolic physiology during surgery, liver and kidney transplant, and the famous Study on Surgical Services of the United States (SOSSUS) report of 1975 that served for decades as a guideline for development of surgical residencies. He was the epitome of what a physician should be, a compassionate and dedicated surgeon, innovative scientist, and a medical professional dedicated to quality medical education across all specialties

    Reducing Cost and Contention of P2P Live Streaming through Locality and Piece Selection

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    The use of locality within peer-to-peer (P2P) networks is ensuring the construction of overlay networks that are both economically viable for network operators and scalable. However, the underlying protocols on which traditional P2P overlays are based are rapidly having to evolve in order to better support more time sensitive, real-time video delivery systems. This shift places greater demand on locality mechanisms to ensure the correct balance between bandwidth savings and successful timely playback. In this paper, we investigate the impact of peer locality within live streaming P2P systems and consider the pertinent challenges when designing locality based algorithms to support efficient P2P live streaming services. Based on our findings we propose an algorithm for supporting locality and harmonised play points in a live streaming P2P system. We present our results and in-depth analysis of its operation though a series of simulations which measure bandwidth consumption at network egress points, failure rates and each peer’s play point relative to the live stream

    Control of TCF-4 Expression by VDR and Vitamin D in the Mouse Mammary Gland and Colorectal Cancer Cell Lines

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    BACKGROUND: The vitamin D receptor (VDR) pathway is important in the prevention and potentially in the treatment of many cancers. One important mechanism of VDR action is related to its interaction with the Wnt/beta-catenin pathway. Agonist-bound VDR inhibits the oncogenic Wnt/beta-catenin/TCF pathway by interacting directly with beta-catenin and in some cells by increasing cadherin expression which, in turn, recruits beta-catenin to the membrane. Here we identify TCF-4, a transcriptional regulator and beta-catenin binding partner as an indirect target of the VDR pathway. METHODOLOGY/PRINCIPAL FINDINGS: In this work, we show that TCF-4 (gene name TCF7L2) is decreased in the mammary gland of the VDR knockout mouse as compared to the wild-type mouse. Furthermore, we show 1,25(OH)2D3 increases TCF-4 at the RNA and protein levels in several human colorectal cancer cell lines, the effect of which is completely dependent on the VDR. In silico analysis of the human and mouse TCF7L2 promoters identified several putative VDR binding elements. Although TCF7L2 promoter reporters responded to exogenous VDR, and 1,25(OH)2D3, mutation analysis and chromatin immunoprecipitation assays, showed that the increase in TCF7L2 did not require recruitment of the VDR to the identified elements and indicates that the regulation by VDR is indirect. This is further confirmed by the requirement of de novo protein synthesis for this up-regulation. CONCLUSIONS/SIGNIFICANCE: Although it is generally assumed that binding of beta-catenin to members of the TCF/LEF family is cancer-promoting, recent studies have indicated that TCF-4 functions instead as a transcriptional repressor that restricts breast and colorectal cancer cell growth. Consequently, we conclude that the 1,25(OH)2D3/VDR-mediated increase in TCF-4 may have a protective role in colon cancer as well as diabetes and Crohn's disease

    Consideration of a New Definition of Clinically Relevant Myocardial Infarction After Coronary Revascularization An Expert Consensus Document From the Society for Cardiovascular Angiography and Interventions (SCAI)

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    Numerous definitions have been proposed for the diagnosis of myocardial infarction (MI) after coronary revascularization. The universal definition for MI designates post procedural biomarker thresholds for defining percutaneous coronary intervention (PCI)-related MI (type 4a) and coronary artery bypass grafting (CABG)-related MI (type 5), which are of uncertain prognostic importance. In addition, for both the MI types, cTn is recommended as the biomarker of choice, the prognostic significance of which is less well validated than CK-MB. Widespread adoption of a MI definition not clearly linked to subsequent adverse events such as mortality or heart failure may have serious consequences for the appropriate assessment of devices and therapies, may affect clinical care pathways, and may result in misinterpretation of physician competence. Rather than using an MI definition sensitive for small degrees of myonecrosis (the occurrence of which, based on contemporary large-scale studies, are unlikely to have important clinical consequences), it is instead recommended that a threshold level of biomarker elevation which has been strongly linked to subsequent adverse events in clinical studies be used to define a "clinically relevant MI." The present document introduces a new definition for "clinically relevant MI" after coronary revascularization (PCI or CABG), which is applicable for use in clinical trials, patient care, and quality outcomes assessment. Numerous definitions for the diagnosis of MI after coronary revascularization are in use (1). A standardized MI definition would provide uniformity for comparing clinical trial results, for assessing patient outcomes and for guiding quality improvement initiatives. In 2007, a "universal definition" for MI following coronary revascularization was proposed (2) and recently revised in 2012 (3). In this document, a PCI-related MI (type 4a) was defined as an increase in cTn to >5Â the 99th percentile of the URL during the first 48 h following PCI (in patients with normal baseline cTn concentrations), plus either: 1) evidence of prolonged ischemia as demonstrated by prolonged chest pain; or 2) ischemic ST-segment changes or new pathological Q waves; or 3) angiographic evidence of a flow limiting complication; or 4) imaging evidence of new loss of viable myocardium or new regional wall motion abnormality. MI associated with CABG (type 5) was defined as an increase in cTn to >10Â the 99th percentile URL during the first 48 h following CABG (in patients with normal baseline cTn concentrations), plus either: 1) new pathological Q waves or new LBBB; or 2) angiographically documente

    Bronchoscopic lung volume reduction with endobronchial valves for patients with heterogeneous emphysema and intact interlobar fissures (the BeLieVeR-HIFi study): a randomised controlled trial

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    Background Lung volume reduction surgery improves survival in selected patients with emphysema, and has generated interest in bronchoscopic approaches that might achieve the same effect with less morbidity and mortality. Previous trials with endobronchial valves have yielded modest group benefits because when collateral ventilation is present it prevents lobar atelectasis. Methods We did a single-centre, double-blind sham-controlled trial in patients with both heterogeneous emphysema and a target lobe with intact interlobar fissures on CT of the thorax. We enrolled stable outpatients with chronic obstructive pulmonary disease who had a forced expiratory volume in 1 s (FEV1) of less than 50% predicted, significant hyperinflation (total lung capacity >100% and residual volume >150%), a restricted exercise capacity (6 min walking distance <450 m), and substantial breathlessness (MRC dyspnoea score ≥3). Participants were randomised (1:1) by computer-generated sequence to receive either valves placed to achieve unilateral lobar occlusion (bronchoscopic lung volume reduction) or a bronchoscopy with sham valve placement (control). Patients and researchers were masked to treatment allocation. The study was powered to detect a 15% improvement in the primary endpoint, the FEV1 3 months after the procedure. Analysis was on an intention-to-treat basis. The trial is registered at controlled-trials.com, ISRCTN04761234. Findings 50 patients (62% male, FEV1 [% predicted] mean 31·7% [SD 10·2]) were enrolled to receive valves (n=25) or sham valve placement (control, n=25) between March 1, 2012, and Sept 30, 2013. In the bronchoscopic lung volume reduction group, FEV1 increased by a median 8·77% (IQR 2·27–35·85) versus 2·88% (0–8·51) in the control group (Mann-Whitney p=0·0326). There were two deaths in the bronchoscopic lung volume reduction group and one control patient was unable to attend for follow-up assessment because of a prolonged pneumothorax. Interpretation Unilateral lobar occlusion with endobronchial valves in patients with heterogeneous emphysema and intact interlobar fissures produces significant improvements in lung function. There is a risk of significant complications and further trials are needed that compare valve placement with lung volume reduction surgery

    Pair-breaking quantum phase transition in superconducting nanowires

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    A quantum phase transition (QPT) between distinct ground states of matter is a wide-spread phenomenon in nature, yet there are only a few experimentally accessible systems where the microscopic mechanism of the transition can be tested and understood. These cases are unique and form the experimentally established foundation for our understanding of quantum critical phenomena. Here we report the discovery that a magnetic-field-driven QPT in superconducting nanowires - a prototypical 1d-system - can be fully explained by the critical theory of pair-breaking transitions characterized by a correlation length exponent ν1\nu \approx 1 and dynamic critical exponent z2z \approx 2. We find that in the quantum critical regime, the electrical conductivity is in agreement with a theoretically predicted scaling function and, moreover, that the theory quantitatively describes the dependence of conductivity on the critical temperature, field magnitude and orientation, nanowire cross sectional area, and microscopic parameters of the nanowire material. At the critical field, the conductivity follows a T(d2)/zT^{(d-2)/z} dependence predicted by phenomenological scaling theories and more recently obtained within a holographic framework. Our work uncovers the microscopic processes governing the transition: The pair-breaking effect of the magnetic field on interacting Cooper pairs overdamped by their coupling to electronic degrees of freedom. It also reveals the universal character of continuous quantum phase transitions.Comment: 22 pages, 5 figure

    Excitation of unidirectional exchange spin waves by a nanoscale magnetic grating

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    Magnon spintronics is a prosperous field that promises beyond-CMOS technology based on elementary excitations of the magnetic order that act as information carriers for future computational architectures. Unidirectional propagation of spin waves is key to the realization of magnonic logic devices. However, previous efforts to enhance the Damon-Eshbach-type nonreciprocity did not realize (let alone control) purely unidirectional propagation. Here we experimentally demonstrate excitations of unidirectional exchange spin waves by a nanoscale magnetic grating consisting of Co nanowires fabricated on an ultrathin yttrium iron garnet film. We explain and model the nearly perfect unidirectional excitation by the chirality of the magneto-dipolar interactions between the Kittel mode of the nanowires and the exchange spin waves of the film. Reversal of the magnetic configurations of film and nanowire array from parallel to antiparallel changes the direction of the excited spin waves. Our results raise the prospect of a chiral magnonic logic without the need for fragile surface states

    A Characterization of Scale Invariant Responses in Enzymatic Networks

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    An ubiquitous property of biological sensory systems is adaptation: a step increase in stimulus triggers an initial change in a biochemical or physiological response, followed by a more gradual relaxation toward a basal, pre-stimulus level. Adaptation helps maintain essential variables within acceptable bounds and allows organisms to readjust themselves to an optimum and non-saturating sensitivity range when faced with a prolonged change in their environment. Recently, it was shown theoretically and experimentally that many adapting systems, both at the organism and single-cell level, enjoy a remarkable additional feature: scale invariance, meaning that the initial, transient behavior remains (approximately) the same even when the background signal level is scaled. In this work, we set out to investigate under what conditions a broadly used model of biochemical enzymatic networks will exhibit scale-invariant behavior. An exhaustive computational study led us to discover a new property of surprising simplicity and generality, uniform linearizations with fast output (ULFO), whose validity we show is both necessary and sufficient for scale invariance of enzymatic networks. Based on this study, we go on to develop a mathematical explanation of how ULFO results in scale invariance. Our work provides a surprisingly consistent, simple, and general framework for understanding this phenomenon, and results in concrete experimental predictions

    Advancing the Role of Proton Therapy for Spine Metastases Through Diagnostic Scan–Based Planning

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    Purpose: Many patients with metastatic cancer live years beyond diagnosis, and there remains a need to improve the therapeutic ratio of metastasis-directed radiation for these patients. This study aimed to assess a process for delivering cost-effective palliative proton therapy to the spine using diagnostic scan–based planning (DSBP) and prefabricated treatment delivery devices. Materials and Methods: We designed and characterized a reusable proton aperture system that adjusts to multiple lengths for spine treatment. Next, we retrospectively identified 10 patients scan treated with thoracic proton therapy who also had a diagnostic computed tomography within 4 months of simulation. We contoured a T6-T9 target volume on both the diagnostic scans (DS) and simulation scans (SS). Using the aperture system, we generated proton plans on the DS using a posterior–anterior beam with no custom range compensator to treat T6-T9 to 8 Gy × 1. Plans were transferred to the SS to compare coverage and normal tissue doses, followed by robustness analysis. Finally, we compared normal tissue doses and costs between proton and photon plans. Results were compared using the Wilcoxon signed-rank test. Results: Median D95% on the DS plans was 101% (range, 100%–102%) of the prescription dose. Median Dmax was 107% (range, 105%–108%). When transferred to SS, coverage and hot spots remained acceptable for all cases. Heart and esophagus doses did not vary between the DS and SS proton plans (P >.2). Robustness analysis with 5 mm X/Y/Z shifts showed acceptable coverage (D95% > 98%) for all cases. Compared with the proton plans, the mean heart dose was higher for both anterior–posterior/posterior–anterior and volumetric modulated arc therapy plans (P < .01). Cost for proton DSBP was comparable to more commonly used photon regimens. Conclusion: Proton DSBP is technically feasible and robust, with superior sparing of the heart compared with photons. Eliminating simulation and custom devices increases the value of this approach in carefully selected patients
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