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Search Results: 1 - 10 of 3609 matches for " Abdullah Yildiz "
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The zero short Covering Problem for finite rings
Abdullah Pa?a,Bahattin Yildiz
Mathematics , 2014,
Abstract: In this work, we find the cardinality of minimal zero short covers of An for any finite local ring A, removing the restriction of D(A)^2 = 0 from the previous works in the literature. Using the structure theorem for Artinian rings, we conclude that we have solved the zero short covering problem for all finite rings. We demonstrate our results on R_k, an infinite family of finite commutative rings extensively studied in coding theory, which satisfy D(A)^2 \neq 0 for all k \geq 2.
New extremal binary self-dual codes from a modified four circulant construction
Abidin Kaya,Bahattin Yildiz,Abdullah Pa?a
Mathematics , 2015,
Abstract: In this work, we propose a modified four circulant construction for self-dual codes and a bordered version of the construction using the properties of \lambda-circulant and \lambda-reverse circulant matrices. By using the constructions on $F_2$, we obtain new binary codes of lengths 64 and 68. We also apply the constructions to the ring $R_2$ and considering the $F_2$ and $R_1$-extensions, we obtain new singly-even extremal binary self-dual codes of lengths 66 and 68. More precisely, we find 3 new codes of length 64, 15 new codes of length 66 and 22 new codes of length 68. These codes all have weight enumerators with parameters that were not known to exist in the literature.
Annular Pancreas in Children: A Decade of Experience
Murat Yigiter,Abdullah Yildiz,Binali Firinci,Onur Yalcin
Eurasian Journal of Medicine , 2010,
Abstract: Objective: Annular pancreas is an uncommon cause of duodenal obstruction in children. In this study, the clinical, radiological, and prognostic findings related to this disorder over a 12-year review period were analyzed.Materials and Methods: A retrospective review of 22 patients with annular pancreas who were treated with surgical repair between April 1998 and February 2010 was performed at two different pediatric surgical units. Presenting symptoms, associated anomalies, radiological findings, the type of surgery performed, postoperative outcomes, and complications were analyzed.Results: Twenty-two patients were identified. Thirteen of the 22 patients (59.1%) were born prematurely, 11 patients (50%) had low birth weight, 2 patients (9.1%) had very low birth weight and 1 patient (4.5%) had extremely low birth weight. The mean birth weight was 2285.23±675.12 g. (970-3300). All patients presented with vomiting, which was bilious in nine (40.9%). Nine patients (40.9%) had chromosomal anomalies. Corrective surgery consisted of duodenoduodenostomy in 9 patients (40.9 %), duodenojejunostomy in 9 patients (40.9%), and gastrojejunostomy in 4 patients (18.1%). Fourteen of the 22 patients have survived (63.6%). The causes of death were combinations of sepsis, pneumonia, brain hemorrhage, and cardiac anomaly. Conclusion: Infants with annular pancreas associated with duodenal obstruction were often born prematurely and/or had low birth weights; many had cardiovascular anomalies. Annular pancreas associated with duodenal obstruction correlated strongly with the trisomy 21 karyotype among the chromosomal anomalies, as did duodenal atresia. The oral feeding tolerance time was nearly the same for all patients regardless of the surgical procedure used.
Dynamic Arbitrageurs’ Long-Run Impacts on Convertible Bond Issuers’ Stock Prices  [PDF]
Serhat Yildiz
Theoretical Economics Letters (TEL) , 2018, DOI: 10.4236/tel.2018.89099
Abstract: I examine convertible bond arbitrageurs’ long-run impact on convertible bond issuers’ stock prices. I find a negative relation between arbitrage activity around convertible bond issues and convertible bond issuers’ long-run stock returns. Average three-year holding period return of convertible bond issuers with no-arbitrage activity around their convertible bond issues is two times larger than that of convertible bond issuers with arbitrage activity around their convertible bond issues. Overall, I show that convertible bond arbitrageurs’ price impact is not limited to short-term [1], but it also has a long-term component.
Lower serum prohepcidin levels associated with lower iron and erythropoietin requirements in hemodialysis patients with chronic hepatitis C
Yasar Caliskan, Berna Yelken, Abdullah Ozkok, Numan Gorgulu, Halil Yazici, Aysegul Telci, Alaattin Yildiz
BMC Nephrology , 2012, DOI: 10.1186/1471-2369-13-56
Abstract: Sixty patients (27 male, 33 female, mean age 50 ±15?years) on chronic HD were included. Parameters related to iron metabolism (ferritin, serum iron and total iron binding capacity (TIBC)), inflammation (hs-CRP, TNF-α and IL-6) and prohepcidin levels were measured. The response to treatment (erythropoiesis-stimulating agent (ESA) resistance index) was assessed from the ratio of the weekly erythropoietin (rhuEPO) dose to hemoglobin (Hb) per unit weight.Serum prohepcidin levels of HCV positive patients (135?±?25?ng/mL) were significantly lower than HCV negative patients [148?±?18?ng/mL, (p?=?0.025)]. Serum IL-6 levels of HCV positive patients were also significantly lower than HCV negative patients (p?=?0.016). Serum prohepcidin levels were positively correlated with ferritin (r?=?0.405, p?=?0.001) and IL-6 (r?=?0.271, p?=?0.050) levels in HD patients. In the HCV positive group, serum prohepcidin levels significantly correlated with ferritin levels (r?=?0.514 p?=?0.004). In the HCV negative group, serum prohepcidin levels significantly correlated with serum IL-6 levels (r?=?0.418, p?=?0.027). In multiple regression analysis performed to predict prohepcidin in HCV positive patients, serum ferritin was found to be an independent variable (r?=?0.28, p?=?0.008).HCV positive HD patients have low levels of serum prohepcidin and IL-6 which might account for iron accumulation together with lower iron and rhuEPO requirements in these patients.
Comparison of fatigue behaviour of eight different hip stems: a numerical and experimental study  [PDF]
Mahmut Pekedis, Hasan Yildiz
Journal of Biomedical Science and Engineering (JBiSE) , 2011, DOI: 10.4236/jbise.2011.410080
Abstract: In this study, finite element analysis was used to investigate the fatigue behavior of eight different hip stems. All of the prostheses investigated in the analysis are already being used in Turkish orthopaedic surgery. All stems were compared with each other in terms of fatigue, deformation and safety factors. Primary analysis was applied on three of the stems, which were tested experimentally. It was observed that the simulation and the experimental results are in good agreement with each other. After determining the reliability of the numerical method, the analysis was applied on all other stems. To obtain a more realistic simulation, boundary conditions were applied according to standards specified in the ISO 7206-4 standard. Three different types of materials were selected during analysis. These materials were Ti-6Al-4V, cobalt chrome alloy and 316L. Minimum fatigue cycles, critical fatigue areas, stresses and safety factor values have been identified. The results obtained from the finite element analysis showed that all stems were safe enough in terms of fatigue life. As a result of fatigue analysis, all stems have been found to be successful, but some of them were found to be better than the others in terms of safety factor. The current study has also demonstrated that analysing hip stems with the finite element method (FEM) can be applied with confidence to support standard fatigue testing and used as an alternative. Further studies can expand the simulations to the clinical relevance due to complex physical relevance.
Unsaponifiable Matter in Carnuba (Cera carnuba) Wax, a Modification of the USP/NF and FCC Methods  [PDF]
Yusuf Yildiz, Manjista Dasgupta
American Journal of Analytical Chemistry (AJAC) , 2016, DOI: 10.4236/ajac.2016.78056
Abstract: Carnuba wax consists chiefly of myricyl cerotate (MW 817.4) and small quantities of free cerotic acid (C26H52O2, Mw 396.7) and myricyl alcohol (C30H62O, mp 90°C). Of the two common extraction solvents, ethyl ether or petroleum ether, Lewkowitsch prefers the former. Concerning separation of phases, he advocates addition of small amounts of alcohol or caustic, and he also states that formation of a flocculant layer between the aqueous layer and the solvent does not interfere with the correct estimation of the unsaponifiable matter. These statements were not corroborated in the hands of this chemist. The “Unsaponifiable Matter” in oils or and fats, which consist mainly of hydrocarbons, sterols and aliphatic alcohols of high molecular mass that are not saponifiable by alkali hydroxides but are soluble in the ordinary fat solvents, and to products of saponification that are soluble in such solvents. Carnuba wax, a rather expensive wax, may be adulterated with less expensive paraffin by dishonest merchants. ASTM has a method for determining paraffinic material in carnuba wax. It uses heptanes at its boiling point to dissolve the wax, apply it to a silica gel column, and elute only the nonpolar (i.e. alkane) material. The method has the disadvantage of using a large volume of haptane, nor is it called for by either US Pharmacopeia/National Formulary (USP/NF) or Food Chemicals Codex (FCC). The test for unsaponifiable matter on pure carnuba wax will yield a result of 50.0% - 55.0%, while a higher result will betray the presence of paraffin adulterants.
Tugba YILDIZ, Ibrahim YILDIZ
Journal of Economics Business and Political Researches , 2017, DOI: 10.25204/iktisad.310148
Abstract: Shadow employment is that the workforce in an economy operates without necessary registrations. It can also be described as working out of a state control and the aim is working without fulfilling responsibilities related with taxation and social security. Carrying out economic activities within the sovereignty of the state, but not making relevant declarations and not fulfilling responsibilities have various effects on the economy both positively and negatively. Since 2011 the ongoing Civil War in Syria has been forcing the people to migrate within the country and abroad, which causes them to be described as refugees. Turkey is in the forefront among the countries where the Syrians have migrated to so far. There are different perceptions about the definition of the legal status of and what would be the legal status of the Syrians who passed on to Turkey from Syrian border. Syrians, who find refuge in Turkey, are legally given a “temporary protection” status and continue their lives there. The costs of following the "open door policy” for Syrian asylum seekers to Turkey, and the problem of shadow employment caused by them in the country have had some effects on the Turkish economy. In this study, the effects of the Syrians under temporary protection on the Turkish economy due to their unregistered employment are evaluated.
Basic Experimental Pancreatitis Models for Beginners  [PDF]
Baris D. Yildiz, Erhan Hamaloglu
Surgical Science (SS) , 2010, DOI: 10.4236/ss.2010.12007
Abstract: Efforts to find an ideal model for pancreatitis date back to 1960’s. Many models are suggested since then. Every model has its own advantages and disadvantages. Some of these models test etiology while others simulate the complications of pancreatitis. An ideal model which by itself demonstrates all aspects of pancreatitis including systemic changes is yet to be described. In this review we tried to gather the basic, easy to construct models.
Phosphoinositide metabolism, lithium and manic depressive illness
Aysegul Yildiz
Spectroscopy: An International Journal , 2002, DOI: 10.1155/2002/535201
Abstract: Physiology underlying manic depressive illness and treating effects of its most commonly used remedy – “lithium” is yet to be elucidated. Recent years of psychopharmacology research witnessed sparkling developments in our understanding of the mechanisms underlying lithium’s mood stabilizing effects. Recent data on molecular biology and in vivo magnetic resonance spectroscopy suggest that some of the initial actions of lithium may occur through the inhibition of the enzyme inositol monophosphatase (IMPase) and reduction of myo–inositol, which in turn initiate a cascade of events at different levels of signal transduction process and gene expression in brain; such as the effects on protein kinase C, myristoylated alenine rich C kinase substrate protein, glycogen synthase kinase 3β, B cell lymphoma–2 protein, and activator protein–I. It is likely that the enzyme IMPase other that being the key point in initiating lithium’s therapeutic effects, may also play a critical role in the physiology underlying manic depressive illness.
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