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Ejaz,Onur Sahin,Islam Ullah Khan
Acta Crystallographica Section E , 2009, DOI: 10.1107/s1600536809043694
Abstract: In the title compound, [ZnBr2(C6H7N)2], the Zn atom (site symmetry 2) adopts a distorted tetrahedral ZnN2Br2 geometry. In the crystal, molecules are linked by N—H...Br hydrogen bonds, generating sheets containing R22(8) loops.
N-Benzyl-N-methyl-3-phenyl-3-[4-(trifluoromethyl)phenoxy]propanamine (N-benzylflouoxetine)
Nosheen Kanwal,Erum Akbar Hussain,Onur Sahin
Acta Crystallographica Section E , 2010, DOI: 10.1107/s1600536810012699
Abstract: In the title compound, C24H24F3NO, the N-benzyl derivative of fluoxetine {N-methyl-3-[4-(trifluoromethyl)phenoxy]benzenepropanamine}, the three aromatic rings A, B and C are inclined to one another by 76.77 (12)° for A/B, 17.05 (14)° for A/C and 89.66 (14)° for B/C. In the crystal structure, molecules are linked via C—H...π interactions to form one-dimensional chains propagating in the [010] direction.
Interference Channel with an Out-of-Band Relay
Onur Sahin,Osvaldo Simeone,Elza Erkip
Mathematics , 2010,
Abstract: A Gaussian interference channel (IC) with a relay is considered. The relay is assumed to operate over an orthogonal band with respect to the underlying IC, and the overall system is referred to as IC with an out-of-band relay (IC-OBR). The system can be seen as operating over two parallel interference-limited channels: The first is a standard Gaussian IC and the second is a Gaussian relay channel characterized by two sources and destinations communicating through the relay without direct links. We refer to the second parallel channel as OBR Channel (OBRC). The main aim of this work is to identify conditions under which optimal operation, in terms of the capacity region of the IC-OBR, entails either signal relaying and/or interference forwarding by the relay, with either a separable or non-separable use of the two parallel channels, IC and OBRC. Here "separable" refers to transmission of independent information over the two constituent channels. For a basic model in which the OBRC consists of four orthogonal channels from sources to relay and from relay to destinations (IC-OBR Type-I), a condition is identified under which signal relaying and separable operation is optimal. When this condition is not satisfied, various scenarios are identified in which interference forwarding and non-separable operation are necessary to achieve optimal performance. In these scenarios, the system exploits the "excess capacity" on the OBRC via interference forwarding to drive the IC-OBR system in specific interference regimes (strong or mixed). The analysis is then turned to a more complex IC-OBR, in which the OBRC consists of only two orthogonal channels, one from sources to relay and one from relay to destinations (IC-OBR Type-II). For this channel, some capacity resuls are derived that parallel the conclusions for IC-OBR Type-I.
Interference Channel with a Half-Duplex Out-of-Band Relay
Onur Sahin,Osvaldo Simeone,Elza Erkip
Mathematics , 2010,
Abstract: A Gaussian interference channel (IC) aided by a half-duplex relay is considered, in which the relay receives and transmits in an orthogonal band with respect to the IC. The system thus consists of two parallel channels, the IC and the channel over which the relay is active, which is referred to as Out-of-Band Relay Channel (OBRC). The OBRC is operated by separating a multiple access phase from the sources to the relay and a broadcast phase from the relay to the destinations. Conditions under which the optimal operation, in terms of the sum-capacity, entails either signal relaying and/or interference forwarding by the relay are identified. These conditions also assess the optimality of either separable or non-separable transmission over the IC and OBRC. Specifically, the optimality of signal relaying and separable coding is established for scenarios where the relay-to-destination channels set the performance bottleneck with respect to the source-to-relay channels on the OBRC. Optimality of interference forwarding and non-separable operation is also established in special cases.
The role of multislice tomography to prevent postoperative strokes related with atherosclerotic plaques in the ascending aorta after coronary artery bypass
I. Oral Hastaoglu,Onur Sokullu,Soner Sanioglu,Sinan Sahin
Anadolu Kardiyoloji Dergisi , 2008,
Abstract: Objective: Atheromatous plaques in the ascending aorta are major risk factors for strokes caused by macroembolization after coronary artery surgery. Detection of plaque formations and changes in the surgical strategy are very important. This study was planned to compare value direct palpation and multislice computerized tomography to establish aortic plaques and to establish clinical predictors of aortic calcification.Methods: Fifty-four patients who underwent coronary bypass surgery were included in this prospective and diagnostic study. Proximal portion of each patient’s aorta was evaluated with multislice computerized tomography and was compared with direct palpation. The efficacy of intraoperative palpation to predict calcifications was studied with ROC analysis and the predictors of aortic plaque formation were analyzed using logistic regression analysis.Results: Atheromatous plaques were detected with palpation in four patients (7.4%), and with multislice tomography in six patients (11.1%). The aortic instrumentation was changed in two patients (3.7%) and strategy was changed in one patient (1.8%). According to the ROC analysis, when multislice computerized tomography was taken as the reference, intraoperative direct palpation was 67% sensitive and 100% specific to predict aortic plaques. Logistic regression analysis of the risk factors showed that the older age was the only significant risk factor (OR – 1.3, 95% CI -1.114-1.568, p=0.001) for plaque formation in the aorta. Neither stroke nor other neurological disorders have been observed during the study. Conclusions: It can be stated that multislice computerized tomography is more effective to show aortic plaques, but it is not sufficient. Multislice tomography may give additional information about the ascending aorta and the opportunity to visualize the aortic arch. It can be preferred in patients with aortic aneurysm or dissection.
Mandibular tam protez l ü modellerinin ü boyutlu bir l üm y ntemiyle kar la t r lmas
Faik Tugut,Fatih Sari,Onur Sahin,Eminnur Ayhan
Cumhuriyet Dental Journal , 2011, DOI: 10.7126/cdj.2012.1100
Abstract: Purpose: The purpose of this study was to investigate with 3 dimensional measurement system whether the stabil condition of mandibular alveolar ridge may recorded by the impression materials. Materials and Methods: The study was performed on the 14 edentulous patients. Patients were divided in two groups. Zinc-oxide eugenol (ZOE) impression material was used as a final impression material in group I and Polyvinylsiloxane (PVS) impression material was used in group II and the definitive cast was obtained. A final impression was made again from all patient with a impression plaster (IP) by means of the custom tray has a new design for each patient. This custom tray was prepared on the definitive cast. The peripheral border line was drawn roughly and the 14 references point were done on the alveolar ridge on the definitive casts. The photographs of the definitive casts were took by Nikon E2/E2s and the three dimensional images were carried out. Height of alveolar ridge, quantity of denture bearing area and length of peripheral border line was measured on the three dimensional images. Results: This study showed that all measurement values of the IP were higher than the others. The measurement values of the ZOE were lower than the IP, but not statistically significant (p>0.05). However, the measurement values of PVS showed that the decrease of height of the alveolar ridge was statistically significant (p< 0.05). Conclusion: The effect of impression materials on the alveolar mucous membrane is vary depending on their properties and the custom tray design. For that reason, it is too important that the choice of impression material and impression technique when the mandibuler complete denture impression is made from edentulous patient has unsupported residual alveolar ridge. It is suggest that an mandibular complete denture impression is made with IP and ZOE. Key Words: Complete denture impression technique, 3-Dimensional measurement system ZET Ama : Bu al man n amac e itli l ü maddeleriyle al nan mandibular alveolar kret l ülerinin stabilitesinin ü boyutlu bir l üm y ntemiyle de erlendirilmesidir. Gere ve Y ntem: Bu al mada 14 di siz hastadan al nan l üler kullan ld . Hastalar iki gruba ayr ld . Son l ü maddesi olarak birinci grupta inko-oksid jenol (ZOE), ikinci grupta polivinilsiloksan (PVS) kullan larak al nan l ülerden ana modeller elde edildi. Ana modeller üzerinden modifiye ahsi ka k haz rlanarak hastalardan l ü al s ile yeniden l üler al nd . Elde edilen modeller üzerinde s n r izgileri tahmini olarak izildi ve alveol kret üze
Interference Mitigation through Successive Cancellation in Heterogeneous Networks
Onur Sahin,Jialing Li,Enoch Lu,Yingxue Li
ISRN Communications and Networking , 2013, DOI: 10.1155/2013/146024
Multi-Layer Hybrid-ARQ for an Out-of-Band Relay Channel
Seok-Hwan Park,Osvaldo Simeone,Onur Sahin,Shlomo Shamai
Mathematics , 2013,
Abstract: This paper addresses robust communication on a fading relay channel in which the relay is connected to the decoder via an out-of-band digital link of limited capacity. Both the source-to-relay and the source-to-destination links are subject to fading gains, which are generally unknown to the encoder prior to transmission. To overcome this impairment, a hybrid automatic retransmission request (HARQ) protocol is combined with multi-layer broadcast transmission, thus allowing for variable-rate decoding. Moreover, motivated by cloud radio access network applications, the relay operation is limited to compress-and-forward. The aim is maximizing the throughput performance as measured by the average number of successfully received bits per channel use, under either long-term static channel (LTSC) or short-term static channel (STSC) models. In order to opportunistically leverage better channel states based on the HARQ feedback from the decoder, an adaptive compression strategy at the relay is also proposed. Numerical results confirm the effectiveness of the proposed strategies.
Multi-Layer Transmission and Hybrid Relaying for Relay Channels with Multiple Out-of-Band Relays
Seok-Hwan Park,Osvaldo Simeone,Onur Sahin,Shlomo Shamai
Mathematics , 2013,
Abstract: In this work, a relay channel is studied in which a source encoder communicates with a destination decoder through a number of out-of-band relays that are connected to the decoder through capacity-constrained digital backhaul links. This model is motivated by the uplink of cloud radio access networks. In this scenario, a novel transmission and relaying strategies are proposed in which multi-layer transmission is used, on the one hand, to adaptively leverage the different decoding capabilities of the relays and, on the other hand, to enable hybrid decode-and-forward (DF) and compress-and-forward (CF) relaying. The hybrid relaying strategy allows each relay to forward part of the decoded messages and a compressed version of the received signal to the decoder. The problem of optimizing the power allocation across the layers and the compression test channels is formulated. Albeit non-convex, the derived problem is found to belong to the class of so called complementary geometric programs (CGPs). Using this observation, an iterative algorithm based on the homotopy method is proposed that achieves a stationary point of the original problem by solving a sequence of geometric programming (GP), and thus convex, problems. Numerical results are provided that show the effectiveness of the proposed multi-layer hybrid scheme in achieving performance close to a theoretical (cutset) upper bound.
Joint Precoding and Multivariate Backhaul Compression for the Downlink of Cloud Radio Access Networks
Seok-Hwan Park,Osvaldo Simeone,Onur Sahin,Shlomo Shamai
Mathematics , 2013, DOI: 10.1109/TSP.2013.2280111
Abstract: This work studies the joint design of precoding and backhaul compression strategies for the downlink of cloud radio access networks. In these systems, a central encoder is connected to multiple multi-antenna base stations (BSs) via finite-capacity backhaul links. At the central encoder, precoding is followed by compression in order to produce the rate-limited bit streams delivered to each BS over the corresponding backhaul link. In current state-of-the-art approaches, the signals intended for different BSs are compressed independently. In contrast, this work proposes to leverage joint compression, also referred to as multivariate compression, of the signals of different BSs in order to better control the effect of the additive quantization noises at the mobile stations (MSs). The problem of maximizing the weighted sum-rate with respect to both the precoding matrix and the joint correlation matrix of the quantization noises is formulated subject to power and backhaul capacity constraints. An iterative algorithm is proposed that achieves a stationary point of the problem. Moreover, in order to enable the practical implementation of multivariate compression across BSs, a novel architecture is proposed based on successive steps of minimum mean-squared error (MMSE) estimation and per-BS compression. Robust design with respect to imperfect channel state information is also discussed. From numerical results, it is confirmed that the proposed joint precoding and compression strategy outperforms conventional approaches based on the separate design of precoding and compression or independent compression across the BSs.
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