1,919 research outputs found

    Temperature dependence of absorption in photorefractive iron-doped lithium niobate crystals

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    We present experimental data showing a significant dependence of light absorption on temperature in photorefractive LiNbO3:Fe crystals. The results are successfully explained by assuming that the widths of the Fe2+ absorption bands in the visible and in the infrared spectral region depend on temperature. The findings are of relevance for thermal fixing of holograms. Furthermore, a temperature-induced increase of the infrared absorption is promising for improved infrared recording

    Poling effect on distribution of quenched random fields in a uniaxial relaxor ferroelectric

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    The frequency dependence of the dielectric permitivity's maximum has been studied for poled and unpoled doped relaxor strontium barium niobate Sr0.61Ba0.39Nb2O6:Cr3+Sr_{0.61}Ba_{0.39}Nb_{2}O_{6}:Cr^{3+} (SBN-61:Cr). In both cases the maximum found is broad and the frequency dispersion is strong. The present view of random fields compensation in the unpoled sample is not suitable for explaining this experimental result. We propose a new mechanism where the dispersion of quenched random electric fields, affecting the nanodomains, is minimized after poling. We test our proposal by numerical simulations on a random field Ising model. Results obtained are in agreement with the polarization's measurements presented by Granzow et al. [Phys. Rev. Lett {\bf 92}, 065701 (2004)].Comment: 7 pages, 4 figure

    Оценка гидрогеодинамического влияния режима эксплуатации скважин на основе статистических функций

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    Исследовано воздействие работы эксплуатационных скважин полигона захоронения промышленных отходов Сибирского химического комбината на колебание напоров в наблюдательных скважинах и выделение частотных составляющих техногенного и природного колебаний в спектре. Показана возможность использования функции взаимной корреляции и Фурье-анализа для оценки гидрогеодинамического влияния режима работы эксплуатационных скважин

    Unpacking ‘women’s health’ in the context of PPPs: a return to instrumentalism in development policy and practice?

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    There has been a significant increase in funding for health programmes in development over the last two decades, partly due to the formation of public–private partnerships. This article examines the impact of public–private partnerships from the perspective of women’s health, asks whether the current culture of funding has led to an increased instrumentalism in women’s health programming and what effects this has on how women’s health is addressed at the level of practice. The article is based on research carried out with UK-based non-governmental organisations (NGOs), and its conclusions raise further challenges for improving women’s health policies and programmes in development

    Langzeitmedikation und perioperatives Management

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    Zusammenfassung: Anästhesisten und Operateure sehen sich zunehmend mit Patienten konfrontiert, die unter einer medikamentösen Dauertherapie stehen. Ein Teil dieser Medikamente können mit Anästhetika oder anästhesiologischen und/oder chirurgischen Interventionen interagieren. Als Folge können Komplikationen wie Blutungen, Ischämien, Infektionen oder schwere Kreislaufreaktionen auftreten. Andererseits birgt oft gerade das perioperative Absetzen von Medikamenten die größere Gefahr. Der Anteil ambulant durchgeführter Operationen hat in den letzten Jahren stark zugenommen und wird voraussichtlich auch in Zukunft zunehmen. Seit Einführung der Fallpauschalen (in der Schweiz bevorstehend) wird der Patient in der Regel erst am Vortag der Operation stationär aufgenommen. Somit sind sowohl zuweisende Ärzte als auch Anästhesisten und Operateure gezwungen, sich frühzeitig mit Fragen der perioperativen Pharmakotherapie auseinanderzusetzen. Dieser Übersichtsartikel behandelt das Management der wichtigsten Medikamentenklassen während der perioperativen Phase. Neben kardial und zentral wirksamen Medikamenten und Wirkstoffen, welche auf die Hämostase und das endokrine System wirken, werden Spezialfälle wie Immunsuppressiva und Phytopharmaka behandel

    Go-6976 reverses hyperglycemia-induced insulin resistance independently of cPKC inhibition in adipocytes.

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    This paper was originally published in PLOS ONE (Robinson KA, Hegyi K, Hannun YA, Buse MG, Sethi JK, PLoS ONE 2014, 9(10): e108963. doi:10.1371/journal.pone.0108963).Chronic hyperglycemia induces insulin resistance by mechanisms that are incompletely understood. One model of hyperglycemia-induced insulin resistance involves chronic preincubation of adipocytes in the presence of high glucose and low insulin concentrations. We have previously shown that the mTOR complex 1 (mTORC1) plays a partial role in the development of insulin resistance in this model. Here, we demonstrate that treatment with Go-6976, a widely used "specific" inhibitor of cPKCs, alleviates hyperglycemia-induced insulin resistance. However, the effects of mTOR inhibitor, rapamycin and Go-6976 were not additive and only rapamycin restored impaired insulin-stimulated AKT activation. Although, PKCα, (but not -β) was abundantly expressed in these adipocytes, our studies indicate cPKCs do not play a major role in causing insulin-resistance in this model. There was no evidence of changes in the expression or phosphorylation of PKCα, and PKCα knock-down did not prevent the reduction of insulin-stimulated glucose transport. This was also consistent with lack of IRS-1 phosphorylation on Ser-24 in hyperglycemia-induced insulin-resistant adipocytes. Treatment with Go-6976 did inhibit a component of the mTORC1 pathway, as evidenced by decreased phosphorylation of S6 ribosomal protein. Raptor knock-down enhanced the effect of insulin on glucose transport in insulin resistant adipocytes. Go-6976 had the same effect in control cells, but was ineffective in cells with Raptor knock-down. Taken together these findings suggest that Go-6976 exerts its effect in alleviating hyperglycemia-induced insulin-resistance independently of cPKC inhibition and may target components of the mTORC1 signaling pathway.This work was supported by grants from the Biotechnology and Biological Sciences Research Council (David Phillips Fellowship, JF16994), Diabetes UK (BDA:RD06/0003237) and British Heart Foundation (PG/10/38/28359) to J.K. Sethi and also from National Institute of Diabetes and Digestive and Kidney Diseases (DK-02001) to M.G. Buse

    Remifentanil does not impair left ventricular systolic and diastolic function in young healthy patients

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    Background Experimental studies and investigations in patients with cardiac diseases suggest that opioids at clinical concentrations have no important direct effect on myocardial relaxation and contractility. In vivo data on the effect of remifentanil on myocardial function in humans are scarce. This study aimed to investigate the effects of remifentanil on left ventricular (LV) function in young healthy humans by transthoracic echocardiography (TTE). We hypothesized that remifentanil does not impair systolic, diastolic LV function, or both. Methods Twelve individuals (aged 18-48 yr) without any history or signs of cardiovascular disease and undergoing minor surgical procedures under general anaesthesia were studied. Echocardiographic examinations were performed in the spontaneously breathing subjects before (baseline) and during administration of remifentanil at a target effect-site concentration of 2 ng ml−1 by target-controlled infusion. Analysis of systolic function focused on fractional area change (FAC). Analysis of diastolic function focused on peak early diastolic velocity of the mitral annulus (e′) and on transmitral peak flow velocity (E). Results Remifentanil infusion at a target concentration of 2 ng ml−1 did not affect heart rate or arterial pressure. There was no evidence of systolic or diastolic dysfunction during remifentanil infusion, as the echocardiographic measure of systolic function (FAC) was similar to baseline, and measures of diastolic function remained unchanged (e′) or improved slightly (E). Conclusion Continuous infusion of remifentanil in a clinically relevant concentration did not affect systolic and diastolic LV function in young healthy subjects during spontaneous breathing as indicated by TT

    Electronic Medical Record Cancer Incidence over Six Years Comparing New Users of Glargine with New Users of NPH Insulin

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    Background: Recent studies suggested that insulin glargine use could be associated with increased risk of cancer. We compared the incidence of cancer in new users of glargine versus new users of NPH in a longitudinal clinical cohort with diabetes for up to 6 years. Methods and Findings: From all patients who had been regularly followed at Massachusetts General Hospital from 1/01/2005 to 12/31/2010, 3,680 patients who had a medication record for glargine or NPH usage were obtained from the electronic medical record (EMR). From those we selected 539 new glargine users (age: 60.1±13.6 years, BMI: 32.7±7.5 kg/m2) and 343 new NPH users (61.5±14.1 years, 32.7±8.3 kg/m2) who had no prevalent cancer during 19 months prior to glargine or NPH initiation. All incident cancer cases were ascertained from the EMR requiring at least 2 ICD-9 codes within a 2 month period. Insulin exposure time and cumulative dose were validated. The statistical analysis compared the rates of cancer in new glargine vs. new NPH users while on treatment, adjusted for the propensity to receive one or the other insulin. There were 26 and 28 new cancer cases in new glargine and new NPH users for 1559 and 1126 person-years follow-up, respectively. There were no differences in the propensity-adjusted clinical characteristics between groups. The adjusted hazard ratio for the cancer incidence comparing glargine vs. NPH use was 0.65 (95% CI: 0.36–1.19). Conclusions: Insulin glargine is not associated with development of cancers when compared with NPH in this longitudinal and carefully retrieved EMR data

    Perioperative administration of fibrinogen does not increase adverse cardiac and thromboembolic events after cardiac surgery

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    Background Although infusion of fibrinogen concentrate is increasingly used in bleeding patients after cardiac surgery, safety data are scarce. We aimed to evaluate the effect of perioperative administration of fibrinogen concentrate on postoperative morbidity and mortality in patients undergoing cardiac surgery. Methods During a 2 yr study period, 991 patients underwent cardiac surgery at a single university centre and were eligible for propensity score (PS) matching. We matched 190 patients with perioperative infusion of fibrinogen concentrate (median dose 2 g) with 190 controls without fibrinogen administration. After PS matching, crude outcome was analysed. Further, a multivariate logistic regression including additional risk factors for adverse outcome was performed. The primary endpoint was a composite of mortality and the occurrence of major cardiac and thromboembolic events within 1 yr. Secondary outcomes included mortality after 30 days and 1 yr and the composite of mortality and adverse events after 30 days. Results The administration of fibrinogen concentrate was not associated with an increased risk for mortality and thromboembolic or cardiac events within 1 yr after cardiac surgery [unadjusted hazard ratio (HR) 0.91; 95% confidence interval (CI) 0.55-1.49; P=0.697]. When using multivariate logistic regression model, the HR for adverse outcome in patients with administration of fibrinogen concentrate was 0.57 (95% CI 0.25-1.17; P=0.101). Similarly, the administration of fibrinogen concentrate did not adversely affect the secondary outcomes when applying unadjusted and multivariate regression analyses. Conclusions Our study strongly suggests that the administration of fibrinogen concentrates at low dose is not associated with thromboembolic complications or adverse outcomes after cardiac surger
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