249 research outputs found

    Advanced receivers for distributed cooperation in mobile ad hoc networks

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    Mobile ad hoc networks (MANETs) are rapidly deployable wireless communications systems, operating with minimal coordination in order to avoid spectral efficiency losses caused by overhead. Cooperative transmission schemes are attractive for MANETs, but the distributed nature of such protocols comes with an increased level of interference, whose impact is further amplified by the need to push the limits of energy and spectral efficiency. Hence, the impact of interference has to be mitigated through with the use PHY layer signal processing algorithms with reasonable computational complexity. Recent advances in iterative digital receiver design techniques exploit approximate Bayesian inference and derivative message passing techniques to improve the capabilities of well-established turbo detectors. In particular, expectation propagation (EP) is a flexible technique which offers attractive complexity-performance trade-offs in situations where conventional belief propagation is limited by computational complexity. Moreover, thanks to emerging techniques in deep learning, such iterative structures are cast into deep detection networks, where learning the algorithmic hyper-parameters further improves receiver performance. In this thesis, EP-based finite-impulse response decision feedback equalizers are designed, and they achieve significant improvements, especially in high spectral efficiency applications, over more conventional turbo-equalization techniques, while having the advantage of being asymptotically predictable. A framework for designing frequency-domain EP-based receivers is proposed, in order to obtain detection architectures with low computational complexity. This framework is theoretically and numerically analysed with a focus on channel equalization, and then it is also extended to handle detection for time-varying channels and multiple-antenna systems. The design of multiple-user detectors and the impact of channel estimation are also explored to understand the capabilities and limits of this framework. Finally, a finite-length performance prediction method is presented for carrying out link abstraction for the EP-based frequency domain equalizer. The impact of accurate physical layer modelling is evaluated in the context of cooperative broadcasting in tactical MANETs, thanks to a flexible MAC-level simulato

    The Importance of Histopathological Examination of the Surgical Spesimen in Pilonidal Sinus Disease

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    Purpose: Although pilonidal sinus disease is common, associated malignancy is very rare. After surgical treatment, most surgeons send the excision material for histopathological examination. The aim of this study was to examine the importance of routinely sending pilonidal sinus surgical excision material for histopathological examination for this examination. Materials and Methods: All patients aged 18 and above who applied to the general surgery clinic electively were included in the study. Demographic information of the patients was recorded and the results of histopathological samples taken from all patients were analyzed, categorizing them as either malignant or benign. Results: In the study, out of the 665 patients included, 551 (82.85%) were male, while 114 (17.15%) were female. Histopathological examination did not reveal any malignancy. Conclusion: No malignancy was reported histopathologically in this study. According to this result; This confirms the question of whether routine histopathological examination of the surgical excision specimen should be considered

    Lactation curve and persistency of Anatolian buffaloes

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    WOS: 000360812300003The aim of this study was to determine the lactation curve traits of Anatolian buffaloes raised under different conditions in farms in Tokat Province, Turkey. Wood's gamma curve parameters were employed to identify the lactation curve types, and values for the parameters beginning yield (a), coefficient of rising (b) and coefficient of decreasing (c) were used to determine the shape and type of lactation curve. All parameters in typical lactation curves were positive, and in the event of one parameter being negative, the curve was considered to be an atypical lactation curve. A total of 690 lactation curves were investigated. It was determined that 406 (58.84%) of these curves were typical, while 90 (13.04%) were concave and 194 (28.12%) of a decreasing type. For typical lactation curves, a, b, c, persistency (S), time after parturition until the peak yield occurs (T-max), maximum daily peak yield (Y-max), and coefficient of determination (R-2) were 7.14 +/- 0.008, 0.85 +/- 2.1, 0.40 +/- 0.001, 2.68, 63.6, 6.41 and 76.33, respectively. For concave lactation curves, values for a, b, c, T-max, Y-max and R-2 were 4.94 +/- 0.42, -0.73 +/- 0.016, -0.23 +/- 0.0038, 95.40, 7.41 +/- 0.004 and 71.68, respectively. For decreasing typical lactation curves, values for a, b, c, T-max, and R-2 were 5.31 +/- 0.0041, -0.15 +/- 0.007, 0.039 +/- 0.0023, 3.89 +/- 0.11 and 79.94, respectively. Parameters predicted by the Wood model within the scope of this study have the potential of being useful for breeding programmes. Further breeding/selection activities could be conducted by using the female Anatolian buffaloes with typical lactation curves

    Apical Root Resorption: A Prospective Radiographic Study of Maxillary Incisors

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    Objectives: The aim of this study was to determine the prevalence of apical root resorption in maxillary incisors during the initial stages of active orthodontic treatment and to test the hypothesis that root resorption increases with the progress of the treatment. Methods: The study sample consisted of 80 teeth of 20 patients (14 female, 6 male) with a mean age of 14.9±2.8 years. Root resorption was determined with standardized digitized periapical radiographs. All the periapical radiographs were obtained at the beginning of orthodontic treatment (T0) and 3 months (T1), 6 months (T2) and 9 months (T3) after the beginning of the treatment by a paralleling device. They were digitalized as 600 dpi with a flatbed scanner and analyzed by software for image analysis at 400x magnification utilizing a personal computer. Results: All of the 4 maxillary incisors had an increasing amount of resorption during the 9-month period. The amount of root resorption between the time intervals was statistically significant (P<.05). Conclusions: Root resorption of maxillary incisors can be detected in the early stages of orthodontic treatment and appears to be related to treatment duration. According to 9-month evaluation period, apical root resorption is of limited clinical significance for the average orthodontic patient.PubMe

    A giant pericardial cyst in an unusual localization

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    Pericardial cysts are rareand benign lesions of the heart. They are usually asymptomatic and incidentally diagnosed on chest X-ray. Most are located at the right cardiophrenic angle. Life- -threatening complications may be infrequently encountered. We report the case of a 54 year- -old male with acute coronary syndrome and a pericardial cyst in an unusual localization

    Effect of spacing on some mechanical properties of narrow leaved ash (Fraxinus angustifolia) wood

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    In this study, conducted to test the effect of spacing on wood quality; the effect of four different spacing types, applied in Adapazarı Süleymaniye plantation (Region 1; 3x2 m; Region 2; 3x2,5 m; Region 3; 3,75x3,75m; Region 4; 4x4 m), on some mechanical properties of narrow leaved ash (Fraxinus angustifolia) have been studied. In the present study, some mechanical properties such as the compression strength parallel to grain,tensile stress perpendicular to grain, bending strength, impact bending strength and modulus of elasticity were determined. As a result, the ash wood, grown in region 4 with a wide range of planting, has high mechanicalproperties. However, when analyzed in terms of wood quality characteristics, it has been found that spacing in region 1 (2x3 m) is more suitable for applications of ash plantations

    A Therapeutic and Diagnostic Dilemma: Granular Cell Tumor of the Breast

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    Six to eight percent of granular cell tumors are seen in the breast. Although mostly benign, they rarely have malignant features clinically and radiologically reminding of breast cancer. This may lead to a potential misdiagnosis of breast carcinoma and overtreatment of patients. The final diagnosis is made by immunohistochemical examination. We performed excisional biopsy on a patient who was diagnosed to have a breast mass. The histopathological examination of the mass revealed granular cell tumor

    Spectrally Efficient Iterative MU-MIMO Receiver for SC-FDMA Based on EP

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    A novel multiuser multiple-input multiple-output (MU-MIMO) receiver for single-carrier frequency-division multiple-access (SC-FDMA) is proposed within the expectation propagation (EP) framework. Recent advances in iterative receiver design show the ability of low complexity EP-based iterative algorithms to achieve performance close to maximum a posteriori (MAP) detection. In this paper, based on the exact derivation of frequency-domain EP-based turbo receivers, we propose a novel spectrally and computationally efficient soft interference canceller (IC) with a doubly-iterative architecture. Asymptotic and finite-length analysis show that our proposal outperforms existing schemes with comparable complexity, in various spatial-multiplexing configurations

    Effects of 8 Weeks of Plyometric Exercise on Certain Physiological Parameters and Performance of Swimmers

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    In this study, it is aimed to review the effects of 8 week plyometric exercises on certain physiological parameters and freestyle swimming performance of swimmers of age 10-11 who practice swimming with a licence in city of Van. Study group has been created by 24 male volunteer swimmers who practice swimming with a licence in city of Van. 24 volunteer athletes aged 10-11, who are licenced swimmers for two years and who exercise regularly 5 days a week have been selected for the study. The athletes are randomly divided into experimental and control groups of 12. Throughout the study, in addition to swimming exercises, experimental group is scheduled to 3 days a week plyometric exercise program. Control group is not given any additional exercise except from the swimming exercises. It is seen that the obtained data does not show normal distribution and non-parametric tests of Mann Whitney U and Wilcoxon Test are used for data analysis. Significance level is taken as p0,05).      As a result, it is seen that the 8 week plyometric exercise has a significant effect on vertical leap and even though not statistically significant, it is pondered that it has a positive effect on freestyle swimming duration of experimental group, compared to that of control group
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