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Search Results: 1 - 10 of 2304 matches for " Ahmet Erdem Sariyuce "
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Incremental Algorithms for Network Management and Analysis based on Closeness Centrality
Ahmet Erdem Sariyuce,Kamer Kaya,Erik Saule,Umit V. Catalyurek
Computer Science , 2013,
Abstract: Analyzing networks requires complex algorithms to extract meaningful information. Centrality metrics have shown to be correlated with the importance and loads of the nodes in network traffic. Here, we are interested in the problem of centrality-based network management. The problem has many applications such as verifying the robustness of the networks and controlling or improving the entity dissemination. It can be defined as finding a small set of topological network modifications which yield a desired closeness centrality configuration. As a fundamental building block to tackle that problem, we propose incremental algorithms which efficiently update the closeness centrality values upon changes in network topology, i.e., edge insertions and deletions. Our algorithms are proven to be efficient on many real-life networks, especially on small-world networks, which have a small diameter and a spike-shaped shortest distance distribution. In addition to closeness centrality, they can also be a great arsenal for the shortest-path-based management and analysis of the networks. We experimentally validate the efficiency of our algorithms on large networks and show that they update the closeness centrality values of the temporal DBLP-coauthorship network of 1.2 million users 460 times faster than it would take to compute them from scratch. To the best of our knowledge, this is the first work which can yield practical large-scale network management based on closeness centrality values.
Finding the Hierarchy of Dense Subgraphs using Nucleus Decompositions
Ahmet Erdem Sariyuce,C. Seshadhri,Ali Pinar,Umit V. Catalyurek
Computer Science , 2014,
Abstract: Finding dense substructures in a graph is a fundamental graph mining operation, with applications in bioinformatics, social networks, and visualization to name a few. Yet most standard formulations of this problem (like clique, quasiclique, k-densest subgraph) are NP-hard. Furthermore, the goal is rarely to find the "true optimum", but to identify many (if not all) dense substructures, understand their distribution in the graph, and ideally determine relationships among them. Current dense subgraph finding algorithms usually optimize some objective, and only find a few such subgraphs without providing any structural relations. We define the nucleus decomposition of a graph, which represents the graph as a forest of nuclei. Each nucleus is a subgraph where smaller cliques are present in many larger cliques. The forest of nuclei is a hierarchy by containment, where the edge density increases as we proceed towards leaf nuclei. Sibling nuclei can have limited intersections, which enables discovering overlapping dense subgraphs. With the right parameters, the nucleus decomposition generalizes the classic notions of k-cores and k-truss decompositions. We give provably efficient algorithms for nucleus decompositions, and empirically evaluate their behavior in a variety of real graphs. The tree of nuclei consistently gives a global, hierarchical snapshot of dense substructures, and outputs dense subgraphs of higher quality than other state-of-the-art solutions. Our algorithm can process graphs with tens of millions of edges in less than an hour.
Statistical Analysis of Bursa Nilufer Creek’s Water Quality Parameters for Period of 2002-2010  [PDF]
?pek Di?dem Yolcu, Feza Karaer, Erkan I?i?i?ok, Erdem Ahmet Albek
Journal of Environmental Protection (JEP) , 2012, DOI: 10.4236/jep.2012.328111
Abstract: Increasing contamination of water resources in the world and our country and decreasing water quality over time, not having met the objectives of utilization of water resources; it has increased the importance of water management. The monitoring of the water resources and evaluation of these monitoring results have given direction to the studies’ outcome in order to control factors that pollute water resources and reduce water quality. Nilüfer Creek is very important for both being a source of drinking and potable water and a discharge area for wastewaters for the city of Bursa. In this study, the results of the analysis belonging to the period between 2002-2010 which are taken from 15 points by General Directorate of Bursa Water and Sewerage Administration (BUWSA) were evaluated in relation to water quality of the Nilüfer Creek. Non-parametric methods were used in the evaluation of the water quality data due to the lack of normally distributed data. The identification of the best represented parameters of the water quality was provided by applying Principal Component Analysis. According to results of the analysis, the best representative 9 parameters from the 19 water quality parameters were defined as parameters of BOD5, COD, TSS, T.Fe, Zn, conductivity, NO2-N, Ni and NO3-N that taking part of the first two components.
Evaluation of ovarian reserve in infertile patients
Mehmet F?rat Mutlu,Ahmet Erdem
Journal of the Turkish-German Gynecological Association , 2012,
Abstract: Diminished ovarian reserve is a more common occurrence as more women postpone childbearing in modern societies due to social and demographic trends. Diminished ovarian reserve is one of the primary reasons for poor ART outcome. Due to high costs, side effects and heavy burden on patients on ART treatments, patient selection and counseling for prognosis is an important aspect before starting ART. Proper prediction of ovarian reserve before initiation of the treatment can decrease cycle cancellations, help clinicians to establish alternative treatment options (i.e.oocyte donation) for poor prognosis patients. However, indicators of ovarian reserve are not fully successful in predicting the outcome of the treatment. In this review, our aim was to discuss the efficacy of ovarian reserve tests on predicting poor ovarian response and treatment outcome in ART patients.
M. Halit YILDIRIM, Ahmet Tuncay ERDEM
Journal of Economics Business and Political Researches , 2016, DOI: 10.25204/iktisad.292102
Abstract: Rapid changes that take place together with the concept of globalization in our age affect both the structures of the enterprises and their activities and functions significantly. Today, it is impossible for businesses to remain indifferent to the outside world and its surroundings. This situation arises from what is called the open system of the enterprises. For this reason, organizations are constantly interacting with their environment. Firms are working to preserve their balanced structure by continuously receive output and input from their environment. In other words, by trying to protect from the uncertainties of the external environment, it tries to maintain its most basic aims of life activities. It is becoming more and more important today to understand and research the strategies that multinational enterprises operating in global markets, especially the ones that they have developed with the structure they have established for survival in the market and not to lose their competitive chances. In the scope of the research, it is tried to investigate how globalization of the "Global Born Enterprises" operating in the international markets in a very short period after the foundation established or as soon as it is established, has traditionally been globalized according to its nationalized competitors. A case study method was applied in the research. Five enterprises with globally emerging business capabilities were interviewed to determine the impact of environmental factors, business values and technology on global emerging businesses. While it has been determined that environmental factors and pursuing developing technology have a positive impact on global emerging businesses, legal requirements and strong competitiveness have been identified as negative factors affecting businesses. It is believed that the literature will contribute to determining what strategies these businesses have developed in order to guide people working in the global business arena.
Results of Montgomery T-Tube in Primary Treatment of Laryngotracheal Stenosis  [PDF]
Hale Aslan, Sedat ?ztürkcan, Erdem Eren, Mehmet Sinan Ba?o?lu, Murat Songu, Erkan Kulduk, Ahmet Erdem K?lavuz, Hüseyin Kat?lm??
International Journal of Otolaryngology and Head & Neck Surgery (IJOHNS) , 2013, DOI: 10.4236/ijohns.2013.25033
Abstract: Introduction: For tracheal stenosis, tracheal resection and anastomosis is widely considered the treatment of choice. However, this surgical approach is not feasible when the glottis and subglottis are involved or in patients with a poor general condition and tracheal stents are a plausible means of providing a permanent or temporary airway opening. Objectives: Evaluate the features and the results of patients with Montgomery T-tube in tracheal stenosis. Methods: Fifteen patients with Myer-Cotton grades 2-3 circular cicatricial tracheal stenosis who received a Montgomery T-tube between 2002-2011 were analyzed in terms of age, gender, etiology, duration of intubation, location and size of the stenotic segment on computed tomography(CT), follow-up time with the T-tube, the complications that occurred after T-tube removed and additional tracheal surgery. Conclusion: A T-tube can be applied in tracheal stenosis at the first treatment before attempting surgery. The patients should be closely followed-up due to the possibility of re-stenosis and other complications.
Evaluation of serum paraoxonase and arylesterase activities in ankylosing spondylitis patients
Erdem, Fazile Hatipoglu;Karatay, Saliha;Yildirim, Kadir;Kiziltunc, Ahmet;
Clinics , 2010, DOI: 10.1590/S1807-59322010000200009
Abstract: objectives: the aim of this study was to investigate the activities of serum paraoxonase and arylesterase in patients with ankylosing spondylitis with respect to those of healthy controls, to assess whether these enzyme levels are related to disease activity and functional capacity. methods: the study included 32 patients with ankylosing spondylitis whose diagnoses were made according to the modified new york criteria as well as 25 healthy controls matched for age and sex. the bath ankylosing spondylitis disease activity index and the bath ankylosing spondylitis functional index were applied to the ankylosing spondylitis patients. as laboratory parameters, the erythrocyte sedimentation rate and serum c-reactive protein level were measured in patients and control subjects. paraoxonase and arylesterase enzyme activities were measured using appropriate methods. results: no statistically significant differences (p>0.05) were found between the ankylosing spondylitis patients and controls in terms of serum paraoxonase or arylesterase levels. furthermore, there was no correlation between clinical and laboratory parameters in patients with ankylosing spondylitis. conclusion: serum paraoxonase and arylesterase levels in ankylosing spondylitis patients may not differ from those of healthy controls, and there is no significant correlation between antioxidant parameters and the bath ankylosing spondylitis disease activity index or bath ankylosing spondylitis functional index scores in ankylosing spondylitis patients. further research is needed to provide deeper understanding of this disease.
Cervical Spinal Cord Injury with a Minor Trauma in A Patient with Ankylosing Spondylitis: A Case Report
Serpil Savas,Erdem Ilgun,A?k?n Gorgulu,Ahmet Yesildag
Romatizma , 2008,
Abstract: Patients with advanced ankylosing spondylitis are prone to fractures of cervical spine following minor injuries. In this case report, we present a case of ankylosing spondylitis where the patient sustained cervical spinal cord injury after a minor traffic accident
Shadow economy and public debt sustainability in Turkey
Bur?in Yereli Ahmet,Se?ilmi? Erdem ?brahim,Ba?aran Alparslan
Economic Annals , 2007, DOI: 10.2298/eka0773085b
Abstract: The aim of this study is to examine the relationship between the shadow economy and public debt in Turkey. We elaborate on the questions regarding the negative effects of shadow economy on the sustainability of public debt observing the estimates about the size of shadow economy in Turkey. In the light of some scholars’ estimates, we re-evaluate the macroeconomic situation of Turkey. At the core of the study, we discuss how the government borrowing policies would differ if the shadow economy was included into the legal system. In order to examine the effects of shadow economy on sustainability, we use various sustainability indicators. There is a significant difference observed between the calculations which take into account the volume of shadow economy as a share of economic system and those that exclude shadow economy as an exogenous variable. .
Clinical outcomes of lung metastasectomy in patients with colorectal cancer
Omer Fatih Olmez,Erdem Cubukcu,Ahmet Sami Bayram,Unsal Akcali
World Journal of Gastroenterology , 2012, DOI: 10.3748/wjg.v18.i7.662
Abstract: AIM: To investigate prognostic factors of survival following curative, non-palliative surgical removal of lung metastases secondary to colorectal cancer (CRC). METHODS: Between 1999 and 2009, a radical metastasectomy with curative intent was performed on lung metastases in 21 patients with CRC (15 male and 6 female; mean age: 57.4 ± 11.8 years; age range: 29-74 years) who had already undergone primary tumour resection. RESULTS: The mean number of lung metastases ranged from one to five. The mean overall survival was 71 ± 35 mo (median: 25 mo). After adjusting for potential confounders, multivariable Cox regression analyses predicted only the number of lung metastases (1 vs ≥ 2; hazard ratio: 7.60, 95% confidence interval: 1.18-17.2, P = 0.03) as an independent predictor of poor survival following lung resection for metastatic CRC. CONCLUSION: Resection of lung metastases is a safe and effective treatment in selected CRC patients with single lung metastases.
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