1,339 research outputs found

    Разработка техники и технологии для осуществления зарезки боковых стволов в добывающих скважинах Нефтегорского месторождения

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    Surface alloys were made on mild steel, coated with nicker and chromium using laser surface alloying. Mild steel was coated with a composite layer of nickel and chromium using the plasma technique. This was followed by laser irradiation using a continuous carbon dioxide laser. Oxidation and corrosion behaviour of these alloys was then determined by carrying out oxidation in air at 800 degrees C and corrosion tests at room temperatures in 1 N H2SO4 With a 75 mu m layer of nickel and chromium each, it was possible to make surface alloys on mild steel, which had a chromium concentration of 6-7 wt%, but the nickel concentration varied from 10-20 wt%. Oxidation behaviour improved significantly over the as-coated specimen and aqueous corrosion improved considerably

    Resonance as the Mechanism of Daytime Periodic Breathing in Patients with Heart Failure

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    Rationale: In patients with chronic heart failure, daytime oscillatory breathing at rest is associated with a high risk of mortality. Experimental evidence, including exaggerated ventilatory responses to CO2 and prolonged circulation time, implicates the ventilatory control system and suggests feedback instability (loop gain > 1) is responsible. However, daytime oscillatory patterns often appear remarkably irregular versus classic instability (Cheyne-Stokes respiration), suggesting our mechanistic understanding is limited. Objectives: We propose that daytime ventilatory oscillations generally result from a chemoreflex resonance, in which spontaneous biological variations in ventilatory drive repeatedly induce temporary and irregular ringing effects. Importantly, the ease with which spontaneous biological variations induce irregular oscillations (resonance “strength”) rises profoundly as loop gain rises toward 1. We tested this hypothesis through a comparison of mathematical predictions against actual measurements in patients with heart failure and healthy control subjects. Methods: In 25 patients with chronic heart failure and 25 control subjects, we examined spontaneous oscillations in ventilation and separately quantified loop gain using dynamic inspired CO2 stimulation. Measurements and Main Results: Resonance was detected in 24 of 25 patients with heart failure and 18 of 25 control subjects. With increased loop gain—consequent to increased chemosensitivity and delay—the strength of spontaneous oscillations increased precipitously as predicted (r = 0.88), yielding larger (r = 0.78) and more regular (interpeak interval SD, r = −0.68) oscillations (P < 0.001 for all, both groups combined). Conclusions: Our study elucidates the mechanism underlying daytime ventilatory oscillations in heart failure and provides a means to measure and interpret these oscillations to reveal the underlying chemoreflex hypersensitivity and reduced stability that foretells mortality in this population

    A novel adaptor protein orchestrates receptor patterning and cytoskeletal polarity in T-cell contacts.

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    Recognition of antigen by T cells requires the formation of a specialized junction between the T cell and the antigen-presenting cell. This junction is generated by the recruitment and the exclusion of specific proteins from the contact area. The mechanisms that regulate these events are unknown. Here we demonstrate that ligand engagement of the adhesion molecule, CD2, initiates a process of protein segregation, CD2 clustering, and cytoskeletal polarization. Although protein segregation was not dependent on the cytoplasmic domain of CD2, CD2 clustering and cytoskeletal polarization required an interaction of the CD2 cytoplasmic domain with a novel SH3-containing protein. This novel protein, called CD2AP, is likely to facilitate receptor patterning in the contact area by linking specific adhesion receptors to the cytoskeleton

    NT-proBNP by Itself Predicts Death and Cardiovascular Events in High-Risk Patients With Type 2 Diabetes Mellitus

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    BACKGROUND: NT-proBNP (N-terminal pro-B-type natriuretic peptide) improves the discriminatory ability of risk-prediction models in type 2 diabetes mellitus (T2DM) but is not yet used in clinical practice. We assessed the discriminatory strength of NT-proBNP by itself for death and cardiovascular events in high-risk patients with T2DM. METHODS AND RESULTS: Cox proportional hazards were used to create a base model formed by 20 variables. The discriminatory ability of the base model was compared with that of NT-proBNP alone and with NT-proBNP added, using C-statistics. We studied 5509 patients (with complete data) of 8561 patients with T2DM and cardiovascular and/or chronic kidney disease who were enrolled in the ALTITUDE (Aliskiren in Type 2 Diabetes Using Cardiorenal Endpoints) trial. During a median 2.6-year follow-up period, 469 patients died and 768 had a cardiovascular composite outcome (cardiovascular death, resuscitated cardiac arrest, nonfatal myocardial infarction, stroke, or heart failure hospitalization). NT-proBNP alone was as discriminatory as the base model for predicting death (C-statistic, 0.745 versus 0.744, P=0.95) and the cardiovascular composite outcome (C-statistic, 0.723 versus 0.731, P=0.37). When NT-proBNP was added, it increased the predictive ability of the base model for death (C-statistic, 0.779 versus 0.744, P<0.001) and for cardiovascular composite outcome (C-statistic, 0.763 versus 0.731, P<0.001). CONCLUSIONS: In high-risk patients with T2DM, NT-proBNP by itself demonstrated discriminatory ability similar to a multivariable model in predicting both death and cardiovascular events and should be considered for risk stratification. REGISTRATION: URL: https://www.clinicaltrials.gov; Unique identifier: NCT00549757

    A False Start in the Race Against Doping in Sport: Concerns With Cycling’s Biological Passport

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    Professional cycling has suffered from a number of doping scandals. The sport’s governing bodies have responded by implementing an aggressive new antidoping program known as the biological passport. Cycling’s biological passport marks a departure from traditional antidoping efforts, which have focused on directly detecting prohibited substances in a cyclist’s system. Instead, the biological passport tracks biological variables in a cyclist’s blood and urine over time, monitoring for fluctuations that are thought to indirectly reveal the effects of doping. Although this method of indirect detection is promising, it also raises serious legal and scientific concerns. Since its introduction, the cycling community has debated the reliability of indirect biological-passport evidence and the clarity, consistency, and transparency of its use in proving doping violations. Such uncertainty undermines the legitimacy of finding cyclists guilty of doping based on this indirect evidence alone. Antidoping authorities should address these important concerns before continuing to pursue doping sanctions against cyclists solely on the basis of their biological passports

    Standardized measurement of coronary inflammation using cardiovascular computed tomography: integration in clinical care as a prognostic medical device

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    Aims: Coronary computed tomography angiography (CCTA) is a first-line modality in the investigation of suspected coronary artery disease (CAD). Mapping of perivascular fat attenuation index (FAI) on routine CCTA enables the non-invasive detection of coronary artery inflammation by quantifying spatial changes in perivascular fat composition. We now report the performance of a new medical device, CaRi-Heart®, which integrates standardized FAI mapping together with clinical risk factors and plaque metrics to provide individualized cardiovascular risk prediction. Methods and results: The study included 3912 consecutive patients undergoing CCTA as part of clinical care in the USA (n = 2040) and Europe (n = 1872). These cohorts were used to generate age-specific nomograms and percentile curves as reference maps for the standardized interpretation of FAI. The first output of CaRi-Heart® is the FAI-Score of each coronary artery, which provides a measure of coronary inflammation adjusted for technical, biological, and anatomical characteristics. FAI-Score is then incorporated into a risk prediction algorithm together with clinical risk factors and CCTA-derived coronary plaque metrics to generate the CaRi-Heart® Risk that predicts the likelihood of a fatal cardiac event at 8 years. CaRi-Heart® Risk was trained in the US population and its performance was validated externally in the European population. It improved risk discrimination over a clinical risk factor-based model [Δ(C-statistic) of 0.085, P = 0.01 in the US Cohort and 0.149, P < 0.001 in the European cohort] and had a consistent net clinical benefit on decision curve analysis above a baseline traditional risk factor-based model across the spectrum of cardiac risk. Conclusion: Mapping of perivascular FAI on CCTA enables the non-invasive detection of coronary artery inflammation by quantifying spatial changes in perivascular fat composition. We now report the performance of a new medical device, CaRi-Heart®, which allows standardized measurement of coronary inflammation by calculating the FAI-Score of each coronary artery. The CaRi-Heart® device provides a reliable prediction of the patient's absolute risk for a fatal cardiac event by incorporating traditional cardiovascular risk factors along with comprehensive CCTA coronary plaque and perivascular adipose tissue phenotyping. This integration advances the prognostic utility of CCTA for individual patients and paves the way for its use as a dual diagnostic and prognostic tool among patients referred for CCTA

    Current trends in the surgical management of Dupuytren’s disease in Europe: an analysis of patient charts

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    Introduction: Dupuytren's disease (DD) causes progressive digital flexion contracture and is more common in men of European descent. Methods: Orthopaedic and plastic surgeons in 12 European countries (the Czech Republic, Denmark, Finland, France, Germany, Hungary, Italy, The Netherlands, Poland, Spain, Sweden and the UK) with >3 and <30 years experience reviewed the medical charts of five consecutive patients they had treated surgically for DD in 2008. Descriptive statistics are reported. Results: In total, 3,357 patient charts were reviewed. Mean (standard deviation) patient age was 61.9 (10.2) years; 81% were men. At the time of the procedure, 11% of patients were at Tubiana stage Ia (0-20° total flexion); 30%, stage Ib (21-45°); 34%, stage II (46-90°); 17%, stage III (91-135°); and 5%, stage IV (&135°). Percutaneous needle fasciotomy was performed in 10%, fasciotomy in 13%, fasciectomy in 69% and dermofasciectomy (DF) in 6% of patients. After surgery, fingers improved a mean of 1.9 Tubiana stages, and 54% of patients had no nodules or contracture. The rate of reported complications during the procedure was 4% overall (11% in patients undergoing DF). The most common postoperative complications reported were haematoma (8%), wound healing complications (6%) and pain (6%). No postoperative complications were reported in 77% of patients. Conclusions: In this European study of more than 3,000 patients with DD, most patients were diagnosed at Tubiana stage I or II, the majority received fasciectomy and more than half had no nodules or contracture remaining after surgery

    Preparing isiXhosa home language teachers for the 21st century classroom: Student teachers' experiences, challenges and reflections

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    The aim of the article is to identify the gaps between theory and practice in pre-service teacher training with special reference to the teaching of isiXhosa as a home language in the Further Education and Training (FET) phase (Grades 10–12) in some Western Cape high schools. The article is based on data that was collected from Postgraduate Certificate in Education (PGCE) students taking isiXhosa (home language) as one of their teaching method subjects as part of their pre-service training. The data were collected by means of an open-ended questionnaire, semi-structured interviews and an analysis of student teachers’ reflective journals. The article provides an analysis of PGCE students’ experiences and reflections on the teaching of isiXhosa as a home language in schools. It argues that if there is a gap between theory underpinning initial pre-service training and actual practice in schools, there will be no significant improvement in the teaching of isiXhosa as a home language. It concludes by proposing ways of improving both pre-service and in-service teacher education practice to develop African languages as academic or intellectual languages at school level

    Three-question set from Michigan Neuropathy Screening Instrument adds independent prognostic information on cardiovascular outcomes: analysis of ALTITUDE trial

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    Abstract: Aims/hypothesis The self-administered Michigan Neuropathy Screening Instrument (MNSI) is used to diagnose diabetic peripheral neuropathy. We examined whether the MNSI might also provide information on risk of death and cardiovascular outcomes. Methods: In this post hoc analysis of the Aliskiren Trial in Type 2 Diabetes Using Cardio-Renal Endpoints (ALTITUDE) trial, we divided 8463 participants with type 2 diabetes and chronic kidney disease (CKD) and/or cardiovascular disease (CVD) into independent training (n = 3252) and validation (n = 5211) sets. In the training set, we identified specific questions that were independently associated with a cardiovascular composite outcome (cardiovascular death, resuscitated cardiac arrest, non-fatal myocardial infarction/stroke, heart failure hospitalisation). We then evaluated the performance of these questions in the validation set. Results: In the training set, three questions (‘Are your legs numb?’, ‘Have you ever had an open sore on your foot?’ and ‘Do your legs hurt when you walk?’) were significantly associated with the cardiovascular composite outcome. In the validation set, after multivariable adjustment for key covariates, one or more positive responses (n = 3079, 59.1%) was associated with a higher risk of the cardiovascular composite outcome (HR 1.54 [95% CI 1.28, 1.85], p < 0.001), heart failure hospitalisation (HR 1.74 [95% CI 1.29, 2.35], p < 0.001), myocardial infarction (HR 1.81 [95% CI 1.23, 2.69], p = 0.003), stroke (HR 1.75 [95% CI 1.20, 2.56], p = 0.003) and three-point major adverse cardiovascular events (MACE) (cardiovascular death, non-fatal myocardial infarction, non-fatal stroke) (HR 1.49 [95% CI 1.20, 1.85], p < 0.001) relative to no positive responses to all questions. Associations were stronger if participants answered positively to all three questions (n = 552, 11%). The addition of the total number of affirmative responses to existing models significantly improved Harrell’s C statistic for the cardiovascular composite outcome (0.70 vs 0.71, p = 0.010), continuous net reclassification improvement (+22% [+10%, +31%], p = 0.027) and integrated discrimination improvement (+0.9% [+0.4%, +2.1%], p = 0.007). Conclusions/interpretation: We identified three questions from the MNSI that provide additional prognostic information for individuals with type 2 diabetes and CKD and/or CVD. If externally validated, these questions may be integrated into the clinical history to augment prediction of CV events in high-risk individuals with type 2 diabetes
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