The Chern-Simons diffusion rate in strongly coupled N=4 SYM plasma in an external magnetic field

We calculate the Chern-Simons diffusion rate in a strongly coupled N=4 SUSY Yang-Mills plasma in the presence of a constant external $U(1)_R$ magnetic flux via the holographic correspondence. Due to the strong interactions between the charged fields and non-Abelian gauge fields, the external Abelian magnetic field affects the thermal Yang-Mills dynamics and increases the diffusion rate, regardless of its strength. We obtain the analytic results for the Chern-Simons diffusion rate both in the weak and strong magnetic field limits. In the latter limit, we show that the diffusion rate scales as $B\times T^2$ and this can be understood as a result of a dynamical dimensional reduction.Comment: 10 pages, 1 figure, typos corrected, comments adde

Testicular Nitric Oxide and Thiobarbituric Acid Reactive Substances Levels in Obstructive Azoospermia: A Possible Role in Pathophysiology of Infertility

Objective. The aim of the study is to evaluate the levels of nitrite/nitrate and thiobarbituric acid reactive substances (TBARS) and their relationship with seminal parameters in experimental obstructive azoospermic rats to explain the possible mechanism of impaired sperm quality in obstructive azoospermia. Methods. A total of 10 male Spraque-Dawley rats underwent bilateral vas resection and ligation (Group-1 = vasectomy group). The findings were compared with control group (Group-2 = sham group, n = 10). Animals were sacrificed 8 weeks after surgery. Testes were removed and used for the evaluation of nitrate/nitrite and TBARS levels and for histology. Epididymal-aspirated seminal plasma was used for semen count and morphological analysis according to the Kruger criteria. Results. Testicular tissue nitrate/nitrite and TBARS levels were 35.7 ± 3.1 μmol/g protein and 3.7 ± 0.1 nmol/g protein in Group-1, and 19.3 ± 0.7 μmol/g protein and 3.1 ± 0.1 nmol/g protein in Group-2, respectively. Both parameters showed statistical differences between the two groups. Testicular tissue nitrate/nitrite and TBARS levels showed negative and statistically significant correlations with sperm motility and morphology. Conclusions. The present study showed that testicular nitrate/nitrite and TBARS levels were increased in obstructive azoospermia. For that reason, we concluded that antioxidant treatment can be recommended to patients before sperm extraction for artificial reproduction due to obstructive infertility after vasectomy reversal

SEREBRAL DEV KİST HİDATİK

Human hydatid disease is endemic in Turkey and brain hydatosis is a childhood disease. The hydatid cysts of the brain are mostly single and 18% of the cases have another visceral involvement. The cysts may rarely reach to gigantic sizes in children. Here, we report a case of gigantic hydatid cyst of the brain in a seven years old boy who presented with signs of increased intracranial pressure. He was successfully operated with Dowling's surgical technique and he is still being followed up with no neurologic sequel. İnsan hidatik hastalığı Türkiye'de endemik olup, beyin hidatozisi çocukluk çağının hastalığıdır. Beyin hidatik kistleri sıklıkla tek olup vakaların %18'inde diğer viseral organlarda tutulum mevcuttur. Kistler çocukluk çağında nadiren çok büyük boyutlara ulaşmaktadır. Bu yazıda artmış kafa içi basıncı bulguları ile başvuran ve beyinde devasal boyutlarda hidatik kisti saptanan yedi yaşında erkek bir olgu sunulmaktadır. Hasta başarıyla Dowling's cerrahi tekniği ile opere edilmiş olup halen sekelsiz olarak takip edilmektedir

A hybrid model for designing attributes sampling plans

Ankara : Department of Industrial Engineering and the Institute of Engineering and Science of Bilkent Univ., 1994.Thesis(Master's) -- Bilkent University, 1994.Includes bibliographical references leaves 50-51In single sampling plans by attributes, statistical and economical considerations have traditionally been discussed separately. An approach taking into account both considerations simultaneously would be more useful in terms o f quality assurance. The suggested model involves minimization o f the expected total cost comprising the inspection cost, the annoyance cost o f rejecting a lot and the cost o f outgoing defective items, while the producer's risk and consumer's risk are not allowed to be greater than specified values. To find the optimal sample size and the optimal acceptance number, a two stage solution method is proposed. The accuracy and the efficiency o f the solution procedure are tested on randomly generated problems, by comparing the solutions obtained by the proposed method to those obtained by enumeration. Sensitivity o f the model is discussed by analyzing the effects o f parameters on the optimal sampling plans.Sanin, M BaşarM.S

Model-Based Multi-Agent RL in Zero-Sum Markov Games with Near-Optimal Sample Complexity

Model-based reinforcement learning (RL), which finds an optimal policy using an empirical model, has long been recognized as one of the corner stones of RL. It is especially suitable for multi-agent RL (MARL), as it naturally decouples the learning and the planning phases, and avoids the non-stationarity problem when all agents are improving their policies simultaneously using samples. Though intuitive, easy-to-implement, and widely-used, the sample complexity of model-based MARL algorithms has not been fully investigated. In this paper, our goal is to address the fundamental question about its sample complexity. We study arguably the most basic MARL setting: two-player discounted zero-sum Markov games, given only access to a generative model. We show that model-based MARL achieves a sample complexity of $\tilde O(|S||A||B|(1-\gamma)^{-3}\epsilon^{-2})$ for finding the Nash equilibrium (NE) value up to some $\epsilon$ error, and the $\epsilon$-NE policies with a smooth planning oracle, where $\gamma$ is the discount factor, and $S,A,B$ denote the state space, and the action spaces for the two agents. We further show that such a sample bound is minimax-optimal (up to logarithmic factors) if the algorithm is reward-agnostic, where the algorithm queries state transition samples without reward knowledge, by establishing a matching lower bound. This is in contrast to the usual reward-aware setting, with a $\tilde\Omega(|S|(|A|+|B|)(1-\gamma)^{-3}\epsilon^{-2})$ lower bound, where this model-based approach is near-optimal with only a gap on the $|A|,|B|$ dependence. Our results not only demonstrate the sample-efficiency of this basic model-based approach in MARL, but also elaborate on the fundamental tradeoff between its power (easily handling the more challenging reward-agnostic case) and limitation (less adaptive and suboptimal in $|A|,|B|$), particularly arises in the multi-agent context

Detecting event-related recurrences by symbolic analysis: Applications to human language processing

Quasistationarity is ubiquitous in complex dynamical systems. In brain dynamics there is ample evidence that event-related potentials reflect such quasistationary states. In order to detect them from time series, several segmentation techniques have been proposed. In this study we elaborate a recent approach for detecting quasistationary states as recurrence domains by means of recurrence analysis and subsequent symbolisation methods. As a result, recurrence domains are obtained as partition cells that can be further aligned and unified for different realisations. We address two pertinent problems of contemporary recurrence analysis and present possible solutions for them.Comment: 24 pages, 6 figures. Draft version to appear in Proc Royal Soc

Estimating Nonaccelerating Inflation Rate Of Unemployment (NAIRU) For Turkey

Bu çalışmada Türkiye için Gordon'un (1997) üçlü modeline benzer bir modelkullanılarak Kalman filtresi yaklaşımıyla zamanla değişen NAIRU (enflasyonuhızlandırmayan işsizlik oranı) tahmini yapılmaktadır. Araştırma dönemi (2000:1-2007:4) için fazla dalgalanmayan bir NAIRU tahmini elde edilmiştir. Çalışmadan eldeedilen NAIRU değerleri Turner vd. (2001) tarafından hesaplanan OECDortalamalarından yüksektir. In this paper, time varying NAIRU (non-accelerating inflation rate ofunemployment) is estimated with Kalman filter approach using model similar toGordon's (1997) triangle model for Turkey. NAIRU estimates are obtained not muchvolatile for the estimation period 2000:1-2007:4. NAIRU rate estimated in this study ishigher from OECD average calculated by Turner et al. (2001)

Resurgence theory, ghost-instantons, and analytic continuation of path integrals

A general quantum mechanical or quantum field theoretical system in the path integral formulation has both real and complex saddles (instantons and ghost-instantons). Resurgent asymptotic analysis implies that both types of saddles contribute to physical observables, even if the complex saddles are not on the integration path i.e., the associated Stokes multipliers are zero. We show explicitly that instanton-anti-instanton and ghostanti-ghost saddles both affect the expansion around the perturbative vacuum. We study a self-dual model in which the analytic continuation of the partition function to negative values of coupling constant gives a pathological exponential growth, but a homotopically independent combination of integration cycles (Lefschetz thimbles) results in a sensible theory. These two choices of the integration cycles are tied with a quantum phase transition. The general set of ideas in our construction may provide new insights into non-perturbative QFT, string theory, quantum gravity, and the theory of quantum phase transitions

Inhomogeneous condensates in the thermodynamics of the chiral NJL2 model

We analyze the thermodynamical properties, at finite density and nonzero temperature, of the (1+1) dimensional chiral Gross-Neveu model (the NJL2 model), using the exact inhomogeneous (crystalline) condensate solutions to the gap equation. The continuous chiral symmetry of the model plays a crucial role, and the thermodynamics leads to a broken phase with a periodic spiral condensate, the "chiral spiral," as a thermodynamically preferred limit of the more general "twisted kink crystal" solution of the gap equation. This situation should be contrasted with the Gross-Neveu model, which has a discrete chiral symmetry, and for which the phase diagram has a crystalline phase with a periodic kink crystal. We use a combination of analytic, numerical, and Ginzburg-Landau techniques to study various parts of the phase diagram