191 research outputs found

    Scalar waves in a wormhole topology

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    Global monochromatic solutions of the scalar wave equation are obtained in flat wormholes of dimensions 2+1 and 3+1. The solutions are in the form of infinite series involving cylindirical and spherical wave functions and they are elucidated by the multiple scattering method. Explicit solutions for some limiting cases are illustrated as well. The results presented in this work constitute instances of solutions of the scalar wave equation in a spacetime admitting closed timelike curves.Comment: 24 pages, 8 figure

    Effects of Short Season Irrigation on Pasture Yield and Predicting Yield With Sentinel-2 Satellite

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    Deficit irrigation can reduce agriculture water use making additional water available for other uses. This study looked at multi-year impacts of deficit irrigation on pasture yield. The results show that that early irrigation provides the most benefit to cool season pastures and late season irrigation only had small impacts on yield. According to this research, irrigation water can be saved without impacting the yield importantly. Remote sensing techniques are becoming a part of agriculture. Yield predictions are important for the farmers and others involved with agriculture. In this research, relationships between the normalized difference vegetation index (NDVI) calculated from remotely sensed data and pasture yields were developed. Additionally, un-maned aerial vehicle (UAV) and Sentinel-2 Satellite images were compared finding a strong correlation between them. This means that Sentinel-2 data which is readily available to the public on 5-day intervals can be used to predict pasture yield. This study was one of the rare studies that UAV and Satellite Images were compared. The correlation between them very high and helped to expand the dataset. The research was sponsored by Utah Agriculture Experiment Station and the cost was about $15,000 per year

    Recent Ferroalloy Studies at Istanbul Technical University

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    The present report is the summary of the experimental studies on the production of ferroalloys and iron-based alloys, which have been conducted in the laboratories of Macro to Nano Research Team (MtNT, Yücel’s Group) at Istanbul Technical University (ITU, Turkey) – Metallurgical and Materials Engineering Department in the last decade. Ferromolybdenum, ferrochromium, ferronickel, and iron-based alloys with alloying elements (Mo, Ni, Cr, etc.) were produced through different reduction processes (metallothermic and carbothermic) starting from different reactant materials such as mill scale, hematite, magnetite, NiO, Cr2O3, chromic acid, and MoO3. The effects of different stoichiometric amounts of reactants and reductant powders were investigated for the production of unalloyed Fe. While, different amounts of metal oxide ratios and their effects on metal recoveries, compositions, and microstructure of final alloys were studied during Fe-based alloys production, raw materials and produced alloys and slags were characterized by using chemical analysis methods (AAS, ICP), X-ray diffraction spectrometry (XRD), X-ray fluorescence spectrometry (XRF), and scanning electron microscopy (SEM/EDS) techniques. Keywords: iron-based alloys, carbothermic reduction, metallothermic reduction, İT

    Roles of the systemic inflammatory response biomarkers in the diagnosis of cancer patients with solid tumors

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    Aim: Cancer is still considered as one of the leading causes of mortality worldwide. Various tumor factors have been used for the diagnosis and follow-up of solid tumors; however, their clinical features remains controversial in terms of their diagnostic, prognostic, and predictive values. In this study, we aimed to investigate the use of the systemic inflammatory response biomarkers, including the neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and lymphocyte-to-monocyte ratio (LMR), in the diagnosis of solid tumors. Method: We retrospectively analyzed the records of 256 patients with solid tumors, including lung, breast, liver, and pancreatic cancers, who were diagnosed at the outpatient clinics of our institution between January 2017 and July 2018. The neutrophil, lymphocyte, monocyte, and platelet counts were measured using a hematology analyzer and the results were analyzed statistically. Results: The results of the receiver operating characteristic analysis showed that the NLR and LMR could be statistically reliable biomarkers, with area under the curve (AUC) values of 0.574 (p = 0.017) and 0.596 (p = 0.002). However, the PLR statistically failed to discriminate the patients and the control subjects, with AUC values of 0.545 (p = 0.148). Conclusions: Certain systemic inflammatory response biomarkers, such as the NLR and LMR, can play roles in the clinical diagnosis of patients with solid tumors

    Effect of addition of live yeast culture on fattening performance on some blood and rumen fluid parameters in male kids fed with sucrose supplemented concentrate

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    The aim of this study were to evaluate the effects of live yeast culture (LYC) as a feed additive on fattening performance, some blood and rumen fluid parameters in male goats fed with sucrose (S) supplemented concentrate. Totally 18 male Saanen goat kids were divided into three groups, no S and LYC (S(-)) as control, 3 % S (S(+)) and 3 % S plus LYC group (S+LYC), each containing 6 kids. Concentrates of groups were formulated as isonitrogenic and isocaloric. LYC (Rumisacc®, Integro Food Industry and Trade Co., İstanbul, Turkey (containing live yeast cell 344 x 1010 cfu per gram) was included in the concentrate at 2% as feed basis. Feeding schedule was established with only concentrate, feed was given ad libitum and roughage was not given. Addition of LYC plus S to concentrate increased ruminal ammonia-N and decreased ruminal pH compeared with sucrose unsupplemented control group. Addition of live yeast culture and sucrose did not affect fattening performance and blood parameters significantly on

    Serum Visfatin, Adiponectin, and Tumor Necrosis Factor Alpha (TNF-α) Levels in Patients with Psoriasis and their Correlation with Disease Severity

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    Psoriasis is a chronic, autoimmune, and inflammatory disease of unknown etiology, characterized by T lymphocyte mediated keratinocyte proliferation. In recent years the relationship between psoriasis and adipose tissue cytokines has been reported. Psoriasis as a triggering factor for the immune and metabolic disorders can be associated with diabetes mellitus, abnormal lipid metabolism, and metabolic syndrome. In this study we assessed the adipose tissue cytokines visfatin, adiponectin, and tumor necrosis factor-α (TNF-α) levels in psoriasis patients and evaluated the relationship between disease severity and cytokines. The study included 42 patients with psoriasis and 42 healthy individuals. Visfatin, adiponectin, and TNF-α levels were measured in both the psoriasis and the control group. The disease severity index was assessed in psoriatic patients by means of PASI. The relationship between visfatin, adiponectin, TNF-α, PASI score, and obesity was evaluated. When serum TNF-α, adiponectin, and visfatin levels of the patient group were compared with those of the control group, the TNF-α levels were statistically higher (p = 0.00) and the adiponectin levels were statistically lower (p = 0.024). The visfatin levels were higher in the psoriatic patients compared to the control group, but this difference was not statistically significant (p = 0.73). The relationship between PASI-TNF-α and between PASI-adiponectin was statistically significant (p = 0.009 and p = 0.004). A positive correlation was observed between body mass index (BMI) and visfatin (p = 0.031). These results indicate that TNF-α and adiponectin play a part in psoriasis etiopathogenesis and can be used as parameters to evaluate the severity of the disease. However, the role of visfatin in psoriasis pathogenesis is unclear. Further clinical studies are needed to clarify the effect of visfatin in psoriatic patients. </p

    Analysis of slicing-tools for fused deposition modeling 3D-printers and comparison of different printers

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    The term 3D printer refers to machines capable of additive manufacturing, which means creating objects by sequential layering. Additive manufactured objects can be used in the whole product life cycle, from rapid prototyping through small series production up to full production. In addition to the hardware itself it is necessary to use tools and applications like "slicing tools", post-production adjustments, process models and testing and verifying scenarios. With slicing tools it is possible to convert digital 3D models into printing instructions for 3D printers. The general approach is: The model is cut into horizontal slices which are then used to create extrusion paths similar to milling paths in the traditional CNC field, which are then being filled with material, mostly plastic material. Commonly the amount of extruded material is being calculated subsequently (price and time estimate). The goal of this study is to compare available slicing tools on multiple 3D printers under defined aspects using different configurations. The main contributions of this study are: 1. Collecting methods and tools to judge print results, 2. Analysis of the available slicing tools and 3D printers with appropriate tests and comparisons and 3. Evaluating the slicing tools using the analysis as solid foundation.Der Begriff 3D-Drucker bezieht sich auf Geräte der additiven Fertigungstechnologie, die Gegenstände durch sequentielle Schichtung erstellen. Objekte, die additiv gefertigt werden, können überall im Produktlebenszyklus, von Rapid Prototyping über die Kleinserienproduktion bis zur Vollproduktion auftreten. Zusätzlich zur eigentlichen Hardware werden Werkzeuge bzw. Anwendungen wie beispielsweise "Slicing Tools" und Post-Produktions Anpassungen, sowie Vorgehensmodelle und Test- und Prüfszenarien nötig. Mit Hilfe dieser Slicing Tools ist es möglich digitale 3D-Modell in Druckanweisungen für 3D-Drucker zu konvertieren. Das allgemeine Vorgehen ist hierbei das folgende: das Modell wird in horizontale Scheiben (Schichten) geschnitten, aus welchen dann Fahrbahnen erzeugt werden, ähnlich der Fräsbahnen im traditionellen CNC-Umfeld, um diese mit Material (meist Kunststoff) zu füllen. Anschließend wird häufig auch die Menge des zu extrudierenden Materials (Kosten- und Zeitabschätzung) berechnet. Diese Fachstudie hat zum Ziel auf verschiedenen 3D-Druckern einen Vergleich der zur Verfügung stehenden Slicing Tools unter verschiedenen Aspekten mittels verschiedener Konfigurationen durchzuführen. Die drei Hauptaufgaben dieser Fachstudie sind: 1. Das Sammeln von Methoden und Werkzeugen zur Beurteilung der Druckergebnisse, 2. Die Analyse der zur Verfügung stehenden Slicing Tools und 3D-Drucker mittels geeigneter Tests und Vergleiche und 3. Das Bewerten der Slicing Tools auf Basis der Untersuchungen

    A combination of plasma DAO and citrulline levels as a potential marker for acute mesenteric ischemia

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    Introduction: There is no valid and reliable diagnostic test for early  diagnosis of acute mesenteric ischemia (AMI). The aim of this study was to measure the plasma levels of diamine oxidase (DAO) and citrulline inAMI to gain insight into its early diagnosis.Material and methods: A total of 21 Wistar albino rats were divided into three groups, that is, control group, short-term ischemia group, and prolonged ischemia group. The superior mesenteric artery was occluded for15 min in the short-term ischemia group and for 12 h in the prolonged ischemia group. Twelve hours later, the experiment was terminated and plasma DAO and citrulline levels were measured. Intestinal tissue wasevaluated for the histopathological changes.Results: Compared to the control group, the short-term and prolonged ischemia groups showed significant increases in the plasma levels of DAO, whereas the plasma citrulline levels decreased significantly. Prolongedischemia caused a larger increase in the plasma DAO levels and a larger decrease in the plasma citrulline levels compared to the short-term ischemia (p0.011 and p0.021, respectively). Intestinal damage was shown to develop more in the prolonged ischemia group (p0.001).Conclusion: In the early period of AMI, the plasma DAO levels increase while citrulline levels decrease, and the extent of these changes depends on the duration of ischemia.Keywords: animal model; experimental; intestines; diamine oxidase; citrullin

    Сравнение различных подходов к оцениванию параметра модели устойчивой авторегрессии первого порядка с дискретным временем

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    Настоящая работа посвящена оцениванию параметра мо- дели устойчивой авторегрессии первого порядка с дискрет- ным временем. В работе проводится сравнительный анализ процедур оценивания параметра модели устойчивой авторе- грессии первого порядка AR(1): последовательная процедура оценивания, усеченная последовательная процедура оцени- вания. Проведено имитационное моделирование, с помощью которого установлено, что обе процедуры позволяют полу- чить оценки с заданной среднеквадратической точностью

    EFFECT OF EXERCISE ON APPETITE-REGULATING HORMONES IN OVERWEIGHT WOMEN

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    Over the past decade, our knowledge of how homeostatic systems regulate food intake and body weight has increased with the discovery of circulating peptides such as leptin, acyl ghrelin, des-acyl ghrelin and obestatin. These hormones regulate the appetite and food intake by sending signals to the brain regarding the body’s nutritional status. The purpose of this study was to investigate the response of appetite-regulating hormones to exercise. Nine overweight women undertook two 2 h trials in a randomized crossover design. In the exercise trial, subjects ran for 60 min at 50% of maximal oxygen uptake followed by a 60 min rest period. In the control trial, subjects rested for 2 h. Obestatin, acyl ghrelin, des-acyl ghrelin and leptin concentrations were measured at baseline and at 20, 40, 60, 90 and 120 min after baseline. A two-way ANOVA revealed a significant (P<0.05) interaction effect for leptin and acyl ghrelin. However, changes in obestatin and des-acyl ghrelin concentration were statistically insignificant (P>0.05). The data indicated that although acute treadmill exercise resulted in a significant change in acyl ghrelin and leptin levels, it had no effect on plasma obestatin and des-acyl ghrelin levels
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