Pervasive spectrum sharing for public safety communications

Yuksel, Murat,Guvenc, Ismail,Saad, Walid,Kapucu, Naim Institute of Electrical and Electronics Engineers 2016 IEEE communications magazine Vol.54 No.3

<P>Next-generation public safety communications (PSC) systems must sustain high-speed, ultra reliable wireless data transmissions. Moving toward this next generation of PSCs warrants a new perspective of increased heterogeneity in emerging wireless architectures and increased multiplexing of wireless spectrum. To realize this vision, models that incentivize users to opportunistically share their spectrum as substrates over possibly multiple hops, and decentralized and open techniques that seamlessly exploit these substrates for public safety applications are much needed. The value of such multihop and multi-technology pervasive spectrum sharing (PSS) is more pronounced for application scenarios in which the need for spectrum access is vital, and infrastructure-less operation is necessary. This article introduces PSS as a new architecture where sharing is the norm, and outlines its vision, principles, and technical challenges.</P>

Second-Line Irinotecan after Cisplatin, Fluoropyrimidin and Docetaxel for Chemotherapy of Metastatic Gastric Cancer

Kucukzeybek, Yuksel,Dirican, Ahmet,Erten, Cigdem,Somali, Isil,Can, Alper,Demir, Lutfiye,Bayoglu, Ibrahim Vedat,Akyol, Murat,Medeni, Murat,Tarhan, Mustafa Oktay Asian Pacific Journal of Cancer Prevention 2012 Asian Pacific journal of cancer prevention Vol.13 No.6

Aim: Tumors of upper gastrointestinal tract are among the cancers that have a quite lethal course. Cytotoxic chemotherapy is the most efficient therapeutic modality for metastatic gastric cancer. In patients who do not respond to first-line treatment, the response rate to second-line therapies is generally low and the toxicity rates high. This study concerned the efficacy and the side effect profile of second-line therapy with irinotecan in the patients who were being followed-up with the diagnosis of metastatic gastric cancer in $\dot{I}$zmir, Turkey. Materials and Methods: We retrospectively evaluated the efficacy and toxicity in 31 patients with metastatic gastric adenocarcinoma who presented to the polyclinic of Medical Oncology of Izmir Ataturk Education and Research Hospital between May 2008 and July 2011. All received chemotherapy regimens containing cisplatin, fluoropyrimidine (5-FU) and docetaxel as the first-line therapy for late stage disease. Irinotecan as a single agent was given at a dose of 210 mg/$m^2$ on each 21 days. Irinotecan (180 mg/$m^2$ on day 1), 5-FU (500 mg/$m^2$ on days 1-2) and leucovorin (LV; 60 mg/$m^2$ on days 1-2) as a combined regimen were given over a 14 day period. Results: Median age was 54 (range, 31-70). Irinotecan was given as a combined regimen for median 6 cycles (range, 3-12) and as a single agent for median 3 cycles (range, 1-10). Metastases were detected in one site in six patients (19%), in two different sites in 17 patients (55%) and in three or more sites in eight patients (26%). Four patients (12.9%) showed partial response and six patients (19.3%) showed stable disease. Progression-free survival (PFS) was found to be 3.26 months (95% CI, 2.3-4.2). Median overall survival (OS) was found to be 8.76 months (95% CI, 4.5-12.9). The most commonly seen grade 3/4 side effect was neutropenia but the the therapy was generally well-tolerated. Conclusions: In this study, it was demonstrated that second-line therapy with irinotecan given following the first-line therapy with cisplatin, fluoropyrimidine (5-FU) and docetaxel was efficient and safe. Further studies are needed for confirmation.

Lack of Any Relationship between ABO and Rh Blood Groups and Clinicopathological Features in Patients with Gastrointestinal Stromal Tumors: Turkish Oncology Group

Urun, Yuksel,Utkan, Gungor,Yalcin, Suayib,CosKun, Hasan Senol,Kocer, Murat,Ozdemir, Nuriye Yildirim,Kaplan, Mehmet Ali,Arslan, Ulku Yalcintas,Ozdemir, Feyyaz,Oztuna, Derya,Akbulut, Hakan,Icli, Fikri Asian Pacific Journal of Cancer Prevention 2012 Asian Pacific journal of cancer prevention Vol.13 No.8

Background: An association between the ABO blood group and the risk of certain malignancies, including pancreatic and gastric cancer, has been reported previously. However, it is unclear whether this association is valid for gastrointestinal stromal tumors (GIST). In this study, ABO blood groups and the Rh factor were investigated in a series of GIST cases. Material and Methods: In 162 patients with GIST, blood group and Rh factor were examined and compared with a control group of 3,022,883 healthy volunteer blood donors of the Turkish Red Crescent between 2004 and 2011. The relationship of blood groups with tumor size, mitotic activity, and age were also evaluated. Results: Overall, the ABO blood group and Rh factor distributions of the 162 patients with GIST were similar to those of the general population. There were no significant differences between both ABO blood types and Rh factor in terms of tumor size, mitotic activity, and age. Conclusion: This is the first study reported on this issue. In our study, we didn't find any relationship between GIST and ABO blood group and Rh factor. However further studies with larger number of patients are needed to establish the role of blood groups in this population.

Adjuvant Chemotherapy and Prognostic Factors in Stage II Colon Cancer - Izmir Oncology Group Study

Kucukzeybek, Yuksel,Dirican, Ahmet,Demir, Lutfiye,Yildirim, Serkan,Akyol, Murat,Yildiz, Yasar,Bayoglu, Ibrahim Vedat,Alacacioglu, Ahmet,Varol, Umut,Salman, Tarik,Yildiz, Ibrahim,Can, Huseyin,Tarhan, M Asian Pacific Journal of Cancer Prevention 2015 Asian Pacific journal of cancer prevention Vol.16 No.6

Background: Although adjuvant chemotherapy is a standard treatment in stage III colon cancer, its benefit is not as clear for stage II patients. In this retrospective analysis, we aimed to evaluate the survival of patients with low-risk stage II colon cancer, the efficacy of adjuvant chemotherapy in high-risk stage II colon cancer patients, and prognostic factors in stage II disease. Materials and Methods: One hundred and seventeen patients who were diagnosed with stage II colon cancer between January 2006 and December 2011 were included in the study. Patients were stratified into two groups as being low-risk and high-risk according to risk factors for stage II disease. Adjuvant 5-fluorouracil-based chemotherapy were administered to the patients with risk factors. Results: Ninety-four patients were treated with adjuvant chemotherapy due to high risk factors and 23 were monitored without treatment. Median follow-up time was 43 months. In terms of disease free survival and overall survival, adjuvant chemotherapy did not provide a statistically significant difference. Univariate analysis demonstrated that bowel obstruction was the major risk factor for shortened disease-free survival, while bowel perforation and perineural invasion were both negative prognostic factors for overall survival. Conclusions: The recommendation of adjuvant chemotherapy for stage II colon cancer is not clear. In our study, it was found that adjuvant chemotherapy did not contribute to survival in high-risk stage II patients. Due to the fact that prognosis of stage II patients is good, many more patients will be needed for statistically significant differences in survival. Adjuvant chemotherapy containing 5 fluorouracil is being used to high-risk stage II patients although it is not a standard treatment approach.

Axisymmetric large deflection analysis of fully and partially loaded shallow spherical shells

Altekin, Murat,Yukseler, Receb F. Techno-Press 2013 Structural Engineering and Mechanics, An Int'l Jou Vol.47 No.4

Geometrically non-linear axisymmetric bending of a shallow spherical shell with a clamped or a simply supported edge under axisymmetric load was investigated numerically. The partial load was introduced by the Heaviside step function, and the solution was obtained by the finite difference and the Newton-Raphson methods. The thickness of the shell was considered to be uniform and the material was assumed to be homogeneous and isotropic. Sensitivity analysis was made for three geometrical parameters. The accuracy of the algorithm was checked by comparing the central deflection, the radial membrane stress at the edge, or the transverse shear force with the solutions of plates and shells in the literature and good agreement was obtained. The main findings of the study can be outlined as follows: (i) If the shell is fully loaded the central deflection of a clamped shell is larger than that of a simply supported shell provided that the shell is not very shallow, (ii) if the shell is partially loaded the central deflection of the shell is sensitive to the parameters of thickness, depth, and partial loading but the influence of the boundary conditions is negligible.

MCPR: Routing Using Parallel Shortest Paths

Ahmet Soran,Murat Yuksel,Mehmet Hadi Gunes 한국통신학회 2024 Journal of communications and networks Vol.26 No.3

Recent trends led to higher data volumes to be transferred and processed over the network. Legacy routing protocols, e.g. OSPF for intra-domain routing, send data from a source to destination on one of the shortest paths. We propose a novel approach to parallelize data transfers by leveraging the multi-core CPUs in the routers. We describe an end-to-end method to optimize data flows on multiple paths. Multi-Core Parallel Routing (MCPR) generates new virtual topology substrates from the underlying router topology and performs the shortest path routing on each substrate. Even though calculating the shortest paths could be done with well-known techniques such as OSPF's Dijkstra implementation, finding optimal substrates and setting their link weights to maximize the network throughput over multiple end-to-end paths is still an NP-hard problem. In MCPR, we focus on designing heuristics for substrate generation from a given router topology. Each substrate is a subgraph of the router topology and each link on each substrate is to be assigned a weight to steer the shortest-path routing for maximal network throughput. Heuristics' interim goal is to generate substrates in such a way that the shortest path between a source-destination pair on each substrate minimally overlaps with the shortest paths calculated by the other substrates. Once these substrates are determined, we assign each substrate to a core in the router and employ a multi-path transport protocol, similar to MPTCP, to perform end-to-end data transfers. We designed heuristics that utilize node centrality, edge centrality, or flow patterns. We evaluated the MCPR heuristics on router-level ISP topologies and compared the network throughput against single shortest-path routing under extensive simulation scenarios including heterogeneous core count across the routers and network failures. The evaluations showed that MCPR heuristics can attain network throughput speedups reaching 2.6 while incurring only polynomial control overhead.

Virtual Direction Multicast: An Efficient Overlay Tree Construction Algorithm

Suat Mercan,Murat Yuksel 한국통신학회 2016 Journal of communications and networks Vol.18 No.3

In this paper, we propose virtual direction multicast(VDM) for video multicast applications on peer-to-peer overlaynetworks. It locates the end hosts relative to each other based ona virtualized orientation scheme using real-time measurements. Itbuilds multicast tree by connecting the nodes, which are estimatedto be in the same virtual direction. By using the concept of directionality,we target to use minimal resources in the underlyingnetwork while satisfying users’ quality expectations. We compareVDMagainst host multicast tree protocol.We simulated the protocolin a network simulator and implemented in PlanetLab. Resultsboth fromsimulation and PlanetLab implementation show that ourproposed technique exhibits good performance in terms of definedmetrics.

Does Blood Flow Change according to Mood? Blood Rheology in Bipolar Disorder

Tevfik Kalelioglu,Murat Kocabiyik,Burcu Kok,Pelin Unalan,Sule Sozen,Ozge Yuksel,Nesrin Karamustafalioglu 대한정신약물학회 2018 CLINICAL PSYCHOPHARMACOLOGY AND NEUROSCIENCE Vol.16 No.3

Objective: Bipolar disorder (BD) is associated with increased rates of cardiovascular diseases. There is growing evidence that blood viscosity may have a common role, correlated with well-known major risk factors that promote cardiovascular disease. In this study we aimed to investigate the whole blood viscosity (WBV) in different stages of BD. Methods: A total of 121 bipolar patients and 41 age-gender matched healthy controls were included. Forty-four of bipolar patients were in manic, 35 were depressed and 42 were in euthymic state. WBV was calculated from hematocrit and total plasma protein according to Simone’s formula at low and high shear rates (LSR and HSR). Results: WBV at HSR of manic group was 16.91±1.01, depressive group was 17.23±0.80, euthymic group was 17.63± 0.95, and control group was 17.52±0.71 (p =0.001). WBV at LSR of manic depressive, euthymic and control group were 53.10±20.58, 60.30±17.02, 68.91±20.33, and 62.01±19.28, respectively (p =0.001). Both WBV at HSR and LSR of manic group was significantly lower than that of the euthymic and control groups (p =0.001 and 0.010 respectively for HSR, p =0.001 and 0.011 respectively for LSR). WBV was significantly positively correlated with lipid profile except high density lipoprotein (HDL). Conclusion: Our results demonstrate a decrement in blood viscosity in manic episode compared with euthymics and controls. Positive correlation of blood viscosity with lipid parameters (except HDL), and negative correlation with number of previous manic episodes suggest that manic episode has favorable effect on cardiovascular risk regarding to blood viscosity.

Relationship between Pulmonary Artery Stiffness and Functional Capacity in Patients with Heart Failure with Reduced Ejection Fraction

Erkan Yildirim,Murat Celik,Uygar Cagdas Yuksel,Mutlu Gungor,Baris Bugan,Deniz Dogan,Yalcin Gokoglan,Hasan Kutsi Kabul,Suat Gormel,Salim Yasar,Mustafa Koklu,Cem Barcin 대한심장학회 2017 Korean Circulation Journal Vol.47 No.6

Background and Objectives: Functional capacity varies significantly among patients with heart failure with reduced ejection fraction (HFrEF), and it remains unclear why functional capacity is severely compromised in some patients with HFrEF while it is preserved in others. In this study, we aimed to evaluate the role of pulmonary artery stiffness (PAS) in the functional status of patients with HFrEF. Methods: A total of 46 heart failure (HF) patients without overt pulmonary hypertension or right HF and 52 controls were enrolled in the study. PAS was assessed on parasternal short-axis view using pulsed-wave Doppler recording of pulmonary flow one centimeter distal to the pulmonic valve annulus at a speed of 100 mm/sec. PAS was calculated according to the following formula: the ratio of maximum flow velocity shift of pulmonary flow to pulmonary acceleration time. Results: PAS was significantly increased in the HFrEF group compared to the control group (10.53±2.40 vs. 7.41±1.32, p<0.001). In sub-group analysis of patients with HFrEF, PAS was significantly associated with the functional class of the patients. HFrEF patients with poor New York Heart Association (NYHA) functional capacity had higher PAS compared those with good functional capacity. In multivariate regression analysis, NYHA class was independently correlated with PAS. Conclusion: PAS is associated with functional status and should be taken into consideration as an underlying pathophysiological mechanism of dyspnea in patients with HFrEF.

Prediction of force reduction factor (R) of prefabricated industrial buildings using neural networks

Arslan, M. Hakan,Ceylan, Murat,Kaltakci, Yaspr M.,Ozbay, Yuksel,Gulay, Fatma Gulten Techno-Press 2007 Structural Engineering and Mechanics, An Int'l Jou Vol.27 No.2

The force (load) reduction factor, R, which is one of the most important parameters in earthquake load calculation, is independent of the dimensions of the structure but is defined on the basis of the load bearing system of the structure as defined in earthquake codes. Significant damages and failures were experienced on prefabricated reinforced concrete structures during the last three major earthquakes in Turkey (Adana 1998, Kocaeli 1999, Duzce 1999) and the experts are still discussing the main reasons of those failures. Most of them agreed that they resulted mainly from the earthquake force reduction factor, R that is incorrectly selected during design processes, in addition to all other detailing errors. Thus this wide spread damages caused by the earthquake to prefabricated structures aroused suspicion about the correctness of the R coefficient recommended in the current Turkish Earthquake Codes (TEC - 98). In this study, an attempt was made for an approximate determination of R coefficient for widely utilized prefabricated structure types (single-floor single-span) with variable dimensions. According to the selecting variable dimensions, 140 sample frames were computed using pushover analysis. The force reduction factor R was calculated by load-displacement curves obtained pushover analysis for each frame. Then, formulated artificial neural network method was trained by using 107 of the 140 sample frames. For the training various algorithms were used. The method was applied and used for the prediction of the R rest 33 frames with about 92% accuracy. The paper also aims at proposing the authorities to change the R coefficient values predicted in TEC - 98 for prefabricated concrete structures.