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Search Results: 1 - 10 of 174 matches for " Ilker Kocyigit "
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Resolution analysis of imaging with $\ell_1$ optimization
Liliana Borcea,Ilker Kocyigit
Mathematics , 2015,
Abstract: We study array imaging of a sparse scene of point-like sources or scatterers in a homogeneous medium. For source imaging the sensors in the array are receivers that collect measurements of the wave field. For imaging scatterers the array probes the medium with waves and records the echoes. In either case the image formation is stated as a sparsity promoting $\ell_1$ optimization problem, and the goal of the paper is to quantify the resolution. We consider both narrow-band and broad-band imaging, and a geometric setup with a small array. We take first the case of the unknowns lying on the imaging grid, and derive resolution limits that depend on the sparsity of the scene. Then we consider the general case with the unknowns at arbitrary locations. The analysis is based on estimates of the cumulative mutual coherence and a related concept, which we call interaction coefficient. It complements recent results in compressed sensing by deriving deterministic resolution limits that account for worse case scenarios in terms of locations of the unknowns in the imaging region, and also by interpreting the results in some cases where uniqueness of the solution does not hold. We demonstrate the theoretical predictions with numerical simulations.
On the Convex Hulls of Self-Affine Fractals
Ibrahim Kirat,Ilker Kocyigit
Mathematics , 2015,
Abstract: Suppose that the set ${\mathcal{T}}= \{T_1, T_2,...,T_q \} $ of real $n\times n$ matrices has joint spectral radius less than $1$. Then for any digit set $ D= \{d_1, \cdots, d_q\} \subset {\Bbb R}^n$, there exists a unique nonempty compact set $F=F({\mathcal{T}},D)$ satisfying $ F = \bigcup _{j =1}^q T_j(F + d_j)$, which is called a self-affine fractal. We consider an existing criterion for the convex hull of $F$ to be a polytope, which is due to Kirat and Kocyigit. In this note, we strengthen our criterion for the case $T_1=T_2=\cdots =T_q $. More specifically, we give an upper bound for the number of steps needed for deciding whether the convex hull of $F$ is a polytope or not. This improves our earlier result on the topic.
Applications of CGO Solutions on Inverse Problems of Coupled-Physics Imaging Methods
Ilker Kocyigit,Ru-Yu Lai,Lingyun Qiu,Yang Yang,Ting Zhou
Mathematics , 2015,
Abstract: This paper surveys inverse problems arising in several coupled-physics imaging modalities for both medical and geophysical purposes. These include Photo-acoustic Tomography (PAT), Thermo-acoustic Tomography (TAT), Electro-Seismic Conversion, Transient Elastrography (TE) and Acousto-Electric Tomography (AET). These inverse problems typically consists of multiple inverse steps, each of which corresponds to one of the wave propagations involved. The review focus on those steps known as the inverse problems with internal data, in which the complex geometrical optics (CGO) solutions to the underlying equations turn out to be useful in showing the uniqueness and stability in determining the desired information.
Pre-Service Teachers’ Comments toward Official Teacher Selection System (Civil Servant Selection Examination, KPSS) in Turkey: A Qualitative Analysis  [PDF]
Ilker Ugulu, Nurettin Yorek
Open Journal of Social Sciences (JSS) , 2015, DOI: 10.4236/jss.2015.39025
Abstract: The purpose of this research is to investigate the opinions of the pre-service teachers toward teacher selection system and civil servant selection exam (KPSS). In this study, qualitative re-search methods and semi-structured interviews were used and researcher-made questionnaires containing open-ended questions were administered. The study group consists of 100 pre-service teachers from four departments (elementary education, biology education, Turkish education, and mathematics education) in Balikesir University (in western Turkey). Pre-service teachers reported that KPSS was not an appropriate examination to select a qualified teacher. Pre-service teachers suggest that both an oral and written examination process should be applied instead of KPSS.
Prevalence of Restless Legs Syndrome in Patients Treated with Peritoneal Dialysis: Clinical and Biochemical Characteristics among Patients with and without Restless Legs Syndrome  [PDF]
Selda Korkmaz, Bulent Tokgoz, Sevda Ismailogullari, Ismail Kocyigit, Merva Kocyigit, Ozgur Berkay Aksu, Murat Aksu
Open Journal of Nephrology (OJNeph) , 2013, DOI: 10.4236/ojneph.2013.31008
Abstract: Introduction and Aims:This is a prospective study identifying prevalence of Restless Legs Syndrome (RLS) in patients ongoing peritoneal dialysis (PD) due to end stage renal disease (ESRD) and comparing clinical and biochemical characteristics among patients with and without RLS. Methods: Two hundred ESRD patients who received PD at least six months assessed by neurologist and nephrologist with regards to presence of RLS. Also, clinical and biochemical features of these patients are determined. One hundred and forty four patients were excluded from study because they had other secondary causes of RLS except for ESRD. Results: Thirteen of 56 patients (23.2%) had RLS. The use of vitamin B + folic acid supplements was significantly lower in patients with RLS than in those without RLS (69.2% vs 97.7%; p = 0.008). There was no significant difference between patient groups with and without RLS in terms of age, gender, body mass index, cause of ESRD, peritoneal membrane transport characteristic, smoking, consuming alcohol, use of erythropoietin, duration of PD, hemoglobin, serum calcium, serum phosphorus, serum albumin, levels of serum iron, total iron binding capacity, ferritin, folic acid and vitamin B12, transferrin saturation, weekly Kt/V urea value, and amount of residual urine volume (p > 0.05). Conclusion: RLS is more common among PD patients than general population. Although essential cause is not exactly known, use of folic acid and vitamin B complex decrease the RLS prevalence in this particular patient group.
Lead Inhibition on Urea Hydrolyzing Microorganisms under Batch Conditions
A. Kilic, H. Kocyigit
Biotechnology & Biotechnological Equipment , 2010, DOI: 10.2478/V10133-010-0079-2
Abstract: Lead, Pb(II), inhibition of microbial calcium precipitation by ureolytic microorganisms was carried out with a glucose containing mineral medium under batch conditions over an incubation period of 120 hours. Substrate removal rate fitted a zero order up to 70th hour and first order kinetic after that time for all samples containing lead concentrations of 0-64 mg/L. The increase of Pb(II) concentrations from 0 to 64 mg/L reduced constant of substrate degradation rate from 10.26 to 4.04 mg glucose/L h, and from 0.027 to 0.005 1/h for zero (k0) and first order kinetic constant (k1), respectively. The Pb(II) at concentration higher than 16 mg/L mainly inhibited both substrate removal and nitrification process. Although nitrification was inhibited at higher concentrations of lead, its inhibition caused precipitation of calcium due to high pH and alkalinity levels in the samples. As a result that a modified Monod inhibition model was applied to BOD data, BOD removal rate inhibited non-competitively. The non-competitive inhibition constants (K1) were 10.4 mg/L for KS, and 37.3 mg/L for Rmax at Pb(II) concentration of 64 mg/L.
The Effect of Aerobic Exercise on Cardiopulmonary System in Children
Dilek Sevimli,Fuat Kocyigit
TAF Preventive Medicine Bulletin , 2009,
Abstract: AIM: The purpose of this study is to investigate the changes in cardiopulmonary system stimulated by aerobic exercise in different age group of children and to find out in which age group aerobic exercise is more effective. METHOD: Totally, 76 children participated in this study. Ages of the participants ranged between 11 17, and mean age was 14.08±0.65. Participants were divided into three groups according to their age range. There were 23 in the first and second and 30 participants in the third group, (15 17), (13 14) and 30 (11 12) respectively. Each of the groups then was divided into two parts one of which was experimental and the other was control group. During 8 weeks, a training programme based on doing aerobic exercise lasting one hour 3 days a week was performed in the experimental groups. Before and after training, EKG, spirometer, blood pressure, heart rate, PWC 170 test of the participants, which was the data collection method, were recorded. The results obtained were compared through t test method of SPSS. RESULTS: The results revealed a decrease in the systolic blood pressure and in the heart rate of those who did exercise as opposed to those who did not do exercise in Group I. In addition, R wave height in V6 of exercise group showed a statistically significant increase. As for second group, it was determined that the R/S, at V1 derivation obtained from the participants who did exercise showed a statistically decrease as compared to those of the participants who did not do exercise. In the third group, no changes were observed in the systolic blood pressure the heart rate, R wave height in V6 and R/S although the measures of PWC 170 test, VC and FVC obtained from all training groups made a significant increase when compared to those of control groups. CONCLUSION: The results of this study revealed that of the three groups the 15 17 age group was affected mostly by the aerobic exercise on kardiyopulmoner sytem. The results suggest that the exercises performed with this group affected the participants positively, which should be taken into consideration for further research. [TAF Prev Med Bull. 2009; 8(2): 125-130]
Maderas. Ciencia y tecnología , 2005, DOI: 10.4067/S0718-221X2005000200006
Abstract: as the bordered pits have generally been thought to have an influence on the refractory nature of softwoods, structural behaviour of this conducting pathways is discussed according to the published literature. various theories on the role of bordered pits to axial flow are expounded in respect to preservative treatment. pit aspiration is also reviewed
Effects of Saccharomyces cerevisiae Yeast on Tibia Bone Characteristics in Rabbits
Ilker Arican
Journal of Animal and Veterinary Advances , 2012, DOI: 10.3923/javaa.2012.1518.1521
Abstract: The effect of feeding different levels of yeast Saccharomyces cerevisiae on tibial bone characteristics of the New Zealand rabbits was studied. An experiment of 85 days duration was conducted with male 5-6 weeks old rabbits. There were 3 dietary treatments each consisting of 7 rabbits in each. The treatments were containing 0 (control), 2 and 4 g kg-1 yeast (Saccharomyces cerevisiae) in their diet, respectively. At the end of the experiment the right tibia of rabbits were dissected from the surrounding tissues and used for bone force and stress measurements. Results show that there is no effect of feeding with different level of Saccharomyces cerevisiae yeast on body weight, tibia weight and length, bone force and stress values of tibia of the rabbits.
Traditional ethnobotanical knowledge about medicinal plants used for external therapies in Alasehir, Turkey
International Journal of Medicinal and Aromatic Plants , 2011,
Abstract: Traditional Ethnobotanical Knowledge (TEK) is the main resource of the all ethnobotanical investigations. Documentation of the TEK through ethnobotanical studies is important for the conservation and utilization of biological resources and should be carried out before such rich heritages are lost due to various anthropogenic and other natural causes. In this reason, the aims of this study is identified not only the medicinal plants used for external therapies by local people of Alasehir District in the Aegean Region of Turkey, but also drawing attention to traditional knowledge that is in danger of being lost. The information including the various data such as local names, ailments and diseases treated, therapeutic effects, parts of plants used and methods of preparation were obtained from local people through individual and face-to-face interviews. Also, the fidelity levels of the species were determined. At the end of the study, it is found that 37 taxa of medicinal plants are used for external therapies by the community. These medicinal plants belong to 27 families. Most used families were Asteraceae and Liliaceae. Allium cepa (100 %) has the highest fidelity level and Ficus carica ssp. carica (65 %) has the lowest. The knowledge of medicinal plants used by the people of Alasehir seems to be well known to its culture and tradition.
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