1,766 research outputs found

    On the partition sum of the NS five-brane

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    We study the Type IIA NS five-brane wrapped on a Calabi-Yau manifold X in a double-scaled decoupling limit. We calculate the euclidean partition function in the presence of a flat RR 3-form field. The classical contribution is given by a sum over fluxes of the self-dual tensor field which reduces to a theta-function. The quantum contributions are computed using a T-dual IIB background where the five-branes are replaced by an ALE singularity. Using the supergravity effective action we find that the loop corrections to the free energy are given by B-model topological string amplitudes. This seems to provide a direct link between the double-scaled little strings on the five-brane worldvolume and topological strings. Both the classical and quantum contributions to the partition function satisfy (conjugate) holomorphic anomaly equations, which explains an observation of Witten relating topological string theory to the quantization of three-form fields.Comment: 35 page

    Supergravity description of spacetime instantons

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    We present and discuss BPS instanton solutions that appear in type II string theory compactifications on Calabi-Yau threefolds. From an effective action point of view these arise as finite action solutions of the Euclidean equations of motion in four-dimensional N=2 supergravity coupled to tensor multiplets. As a solution generating technique we make use of the c-map, which produces instanton solutions from either Euclidean black holes or from Taub-NUT like geometries.Comment: 35 pages, some clarifications adde

    Responsivity and Reproducibility of Sputum Inflammatory Biomarkers During COPD Exacerbation and Stable Phases - A Pilot Study

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    Introduction: There is a great interest to identify airway biomarkers to evaluate the potential and efficacy of anti-inflammatory therapeutic interventions. In this pilot study, we compared cytokine mRNA and protein levels of IL-6, IL-8, CCL2, CCL4, and TNF-α, as well as LTB-4 expression regarding their reproducibility and responsivity in induced sputum in COPD patients. Methods: We recruited a cohort of 17 patients with a moderate COPD exacerbation, necessitating antibiotics and/or oral corticosteroids. Patients were followed for two consecutive stable phase visits. Cytokine mRNA and protein levels were measured in induced sputum samples. Results: IL-6 and CCL4 protein levels decreased from exacerbation to stable phase, whereas their mRNA expression showed the same trend (not statistically significant). Coefficients of variation were overall lower (ie, more favorable for responsiveness) at protein levels compared to mRNA levels. No significant differences were observed in the reproducibility between cytokine mRNA expression and protein measurements. IL-6, IL-8, CCL2, and TNF-α gene expression levels yielded moderate to high intraclass correlation coefficients and/or Spearman correlation coefficients between both stable phase samples in contrast to their protein levels. Conclusion: Our findings suggest that several protein levels yield better responsivity with lower noise-to-signal ratios compared to their respective mRNA levels. In contrast, cytokine mRNA expression was more reproducible as it varied less in a stable state than proteins. Future studies are needed with a larger sample size to further evaluate the differences of responsivity and reproducibility between cytokine mRNA and protein measurements, not only during exacerbations

    Holomorphic anomaly and matrix models

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    The genus g free energies of matrix models can be promoted to modular invariant, non-holomorphic amplitudes which only depend on the geometry of the classical spectral curve. We show that these non-holomorphic amplitudes satisfy the holomorphic anomaly equations of Bershadsky, Cecotti, Ooguri and Vafa. We derive as well holomorphic anomaly equations for the open string sector. These results provide evidence at all genera for the Dijkgraaf--Vafa conjecture relating matrix models to type B topological strings on certain local Calabi--Yau threefolds.Comment: 23 pages, LaTex, 3 figure

    Pulmonary Hypertension in Patients with Chronic Fibrosing Idiopathic Interstitial Pneumonias

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    Background Pulmonary hypertension (PH) is a common finding in patients with chronic fibrosing idiopathic interstitial pneumonias (IIP). Little is known about the response to pulmonary vasodilator therapy in this patient population. COMPERA is an international registry that prospectively captures data from patients with various forms of PH receiving pulmonary vasodilator therapies. Methods We retrieved data from COMPERA to compare patient characteristics, treatment patterns, response to therapy and survival in newly diagnosed patients with idiopathic pulmonary arterial hypertension (IPAH) and PH associated with IIP (PH-IIP). Results Compared to patients with IPAH (n = 798), patients with PH-IIP (n = 151) were older and predominantly males. Patients with PH-IIP were treated predominantly with phosphodiesterase-5 inhibitors (88% at entry, 87% after 1 year). From baseline to the first follow-up visit, the median improvement in 6MWD was 30 m in patients with IPAH and 24.5 m in patients with PH-IIP (p = 0.457 for the difference between both groups). Improvements in NYHA functional class were observed in 22.4% and 29.5% of these patients, respectively (p = 0.179 for the difference between both groups). Survival rates were significantly worse in PH-IIP than in IPAH (3-year survival 34.0 versus 68.6%; p<0.001). Total lung capacity, NYHA class IV, and mixed-venous oxygen saturation were independent predictors of survival in patients with PH-IIP. Conclusions Patients with PH-IIP have a dismal prognosis. Our results suggest that pulmonary vasodilator therapy may be associated with short-term functional improvement in some of these patients but it is unclear whether this treatment affects survival

    Внутренние источники финансирования инвестиционной деятельности в Украине

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    В статье рассмотрены 4 основных источника финансирования инвестиционной деятельности, и проблемы связанные с их формированием и использованием. Учитывая непосредственное влияние внутренних источников инвестиций на экономический рост, и их минимальное использование в Украине, тема становится актуальной, требующей детальной проработки.У статті розглянуті 4 основні джерела фінансування інвестиційної діяльності та проблеми, пов'язані з їх формуванням та використанням. З огляду на безпосередній вплив внутрішніх джерел інвестицій на економічний зріст, та їх мінімальне використання в Україні, тема стає актуальною, потребуючою детального опрацювання.Four basic sources of financing investment activity as well as problems related to their forming and use are considered in the article. This theme is essential and needs detailed development under circumstances of direct impact of the internal sources of investment on economical growth and still minimum use in Ukraine

    Quality Improvement of Pancreatic Surgery by Centralization in the Western Part of the Netherlands

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    BACKGROUND: Centralization of pancreatic surgery in high-volume hospitals is under debate in many countries. In the western part of the Netherlands, the professional network of surgical oncologists agreed to centralize all pancreatic surgery from 2006 in two high-volume hospitals. Our aim is to evaluate whether centralization of pancreatic surgery has improved clinical outcomes and has changed referral patterns. MATERIALS AND METHODS: Data of the Comprehensive Cancer Centre West (CCCW) of all 249 patients who had a resection for suspected pancreatic cancer between 1996 and 2008 in the western part of the Netherlands were analyzed. Multivariable modeling was used to evaluate survival for 3 time periods; 1996–2000, 2001–2005 (introduction of quality standards), and 2006–2008 (after centralization). In addition, the differences in referral pattern were analyzed. RESULTS: From 2006, all pancreatic surgery was centralized in 2 hospitals. The 2-year survival rate increased after centralization from 39% to 55% (P = .09) for all patients who had a pancreatic resection for pancreatic cancer. After adjustment for age, tumor location, stage, histology, and adjuvant treatment, the latter period was significantly associated with improved survival (hazard ratio [HR] 0.50; 95% confidence interval [95% CI] 0.34–0.73). CONCLUSIONS: Centralization of pancreatic surgery was successful and has resulted in improved clinical outcomes in the western part of the Netherlands, demonstrating the effectiveness of centralization

    Likely questionnaire-diagnosed food allergy in 78, 890 adults from the northern Netherlands

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    Background It is challenging to define likely food allergy (FA) in large populations which limited the number of large studies regarding risk factors for FA. Objective We studied the prevalence and characteristics of self-reported FA (s-rFA) in the large, population-based Dutch Lifelines cohort and identified associated risk factors. Methods Likely food allergic cases (LikelyFA) were classified based on questionnaire reported characteristics consistent with FA. Subjects with atypical characteristics were classified as Indeterminate. We investigated 13 potential risk factors for LikelyFA such as birth mode and living on a farm and addressed health-related quality of life (H-RQOL). Results Of the 78, 890 subjects, 12.1% had s-rFA of which 4.0% and 8.1% were classified as LikelyFA and Indeterminate, respectively. Younger age, female sex, asthma, eczema and nasal allergy increased the risk of LikelyFA (p-value range <1.00*10−250–1.29*10−7). Living in a small city/large village or suburb during childhood was associated with a higher risk of LikelyFA than living on a farm (p-value = 7.81*10−4 and p = 4.84*10−4, respectively). Subjects classified as Indeterminate more often reported depression and burn-out compared to those without FA (p-value = 1.46*10−4 and p = 8.39*10−13, respectively). No association was found with ethnicity, (duration of) breastfeeding, birth mode and reported eating disorder. Mental and physical component scores measuring H-RQOL were lower in both those classified as LikelyFA and Indeterminate compared to those without FA. Conclusion The prevalence of s-rFA among adults is considerable and one-third reports characteristics consistent with LikelyFA. Living on a farm decreased the risk of LikelyFA. The association of poorer H-RQOL as well as depression and burn-out with questionable self-perceived FA is striking and a priority for future study
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