Enhancements of electron-positron pair production at very low transverse momentum in peripheral hadronic A + A collisions

The STAR collaboration has observed an excess production of electron-positron pairs which have transverse momenta pperp < 150 MeV/c in peripheral gold-gold and uranium-uranium collisions. ALICE has also reported on an excess of mu mu pairs at low pperp in very peripheral lead-lead collisions at a center-of-mass energy of 2.76 TeV/nucleon pair. In literature, there are number of studies about the electromagnetic lepton pair productions in peripheral heavy-ion collisions. Almost all of them have a prediction that unitary is violated in these high energies so that probability of producing electron-positron pairs is greater than one. It is clear that at RHIC and LHC energies, probabilities of producing electron-positron pairs for impact parameters smaller than Compton-wavelength of electron is greater than one. This means that for small impact parameters where the electric field is strongest multiple electron-positron pair productions is inescapable and it must be included in calculations. In literature, there are number of explanations about the pperp broadening however none of them has included the multi-pair production processes in their calculations. The aim of this paper is to show that electron-positron multi-pair production cross section is large and it can not be ignored in calculations

Finite dimensional backstepping controller design

We introduce a finite dimensional version of backstepping controller design for stabilizing solutions of PDEs from boundary. Our controller uses only a finite number of Fourier modes of the state of solution, as opposed to the classical backstepping controller which uses all (infinitely many) modes. We apply our method to the reaction-diffusion equation, which serves only as a canonical example but the method is applicable also to other PDEs whose solutions can be decomposed into a slow finite-dimensional part and a fast tail, where the former dominates the evolution in large time. One of the main goals is to estimate the sufficient number of modes needed to stabilize the plant at a prescribed rate. In addition, we find the minimal number of modes that guarantee the stabilization at a certain (unprescribed) decay rate. Theoretical findings are supported with numerical solutions.Comment: 28 pages, 2 figure

Genetska struktura i demografska prošlost populacija pišmolja Merlangius merlangus (Linnaeus, 1758) s područja Turske određene na temelju varijacija mitohondrijskih DNA sekvenci

The genetic diversity, structure, and demographic history of the economically important and overfished Gadidae species Merlangius merlangus were investigated using the non-coding mitochondrial Control Region (CR) from five different sites in the Sea of Marmara and the Black Sea in Turkey. The populations of M. merlangus were found to be genetically diverse, with 14 haplotypes and 15 polymorphic regions. The overall haploid diversity was 0.910 ± 0.024, and the nucleotide diversity was 0.003 ± 0.0003. Genetic distances between populations varied between 0.13% and 8.02%, while genetic distances within M. merlangus populations varied between 0.09% and 0.42%. Principle Coordinates Analysis showed that Marmara, Black Sea, and Karadeniz Ereğli populations were clearly separated. Pairwise FST values varied from 0.12 to 0.69, highlighting high genetic variation among populations. The Black Sea and Marmara lineages of M. merlangus diverged from the North Sea lineage 1.65 (1.08-2.29) mya, whereas the separation between the Atlantic lineage occurred about 0.84 (0.51-1.2) mya. The recent expansion of the whiting population was identified through neutrality tests and mismatch distribution analyses. This study provides important insight into the genetic structure, conservation, and management of this species.Genetska raznolikost, struktura i demografska prošlost ekonomski važne i prelovom ugrožene vrste pišmolja Merlangius merlangus istraživane su korištenjem nekodirajuće mitohondrijske kontrolne regije (CR) s pet različitih lokaliteta u Mramornom i Crnom moru u Turskoj. Populacije M. merlangus pokazale su genetičku raznolikost s 14 haplotipova i 15 polimorfnih regija. Ukupna haplotipna raznolikost iznosila je 0.910 ± 0.024, a nukleotidna raznolikost 0.003 ± 0.0003. Genetske udaljenosti između populacija varirale su između 0.13% i 8.02%, dok su genetske udaljenosti unutar populacija M. merlangus varirale između 0.09% i 0.42%. Analiza glavnih koordinata (PCoA) pokazala je jasnu razdvojenost populacija iz Mramornog i Crnog mora te Karadeniz Ereğli područja. Uparene Fst vrijednosti varirale su od 0.12 do 0.69, ukazujući na visoku genetičku varijabilnost između populacija. Genealoške linije pišmolja iz Mramornog i Crnog mora odvojile su se od linija iz Sjevernog mora prije 1.65 (1.08-2.29) milijuna godina, dok se odvajanje od atlantske linije dogodilo prije oko 0.84 (0.51-1.2) milijuna godina. Nedavno širenje populacije pišmolja utvrđeno je putem testova neutralnosti i analize neusklađenosti distribucije. Ovo istraživanje donosi bitne spoznaje o genetskoj strukturi, očuvanju i upravljanju ovom vrstom

Sinema Sanatı Karşısında İki Aydın: Necip Fazıl Kısakürek ve Nazım Hikmet

Çağdaş Türk şiirinin en önemli temsilcilerinden Necip Fazıl Kısakürek ve Nazım Hikmet yalnızca şair kimlikleriyle değil, düşünce dünyaları ve dünya görüşleriyle de kuşaklar üzerinde derin etkiler uyandırmış isimler olarak karşımıza çıkmaktadır. Fakat günümüze değin her iki şairin düşünce dünyalarını mukayeseli olarak ele alan araştırmalarda çoğunlukla aralarındaki ideolojik ihtilafların ön plana çıkarıldığı; üzerinde uzlaşıya vardıkları hususlarınsa farklı nedenlerle ihmal edildiği görülmektedir. Buna mukabil tanışıklıkları Bahriye Mektebi sıralarına dayanan Necip Fazıl Kısakürek ve Nazım Hikmet’in, yaşadıkları çağın kimi güncel gelişmeleri karşısında aynı tavrı aldıkları iddia edilebilir. Bunların başında sinema gelmektedir. Söz konusu şairlerin sinema sanatına yönelik tespit, yaklaşım, düşünce ve eleştirileri dikkat çekici bir biçimde örtüşmektedir. Bu çalışmanın amacı, şairlerin sinema sanatı hakkındaki görüşleri arasındaki benzerlikleri ortaya koymak ve bu suretle kendilerinin ideolojik kimliklerine dair tartışmalara farklı bir boyut kazandırmaya çalışmaktadır

Modelling and simulation studies on adaptive controller for alt-azimuth telescopes despite unknown wind disturbance and mass

Numerous ground-based observatories are using small sized ground telescopes for scientific research purposes. The telescopes that are available on the market have three main problems. These issues can be listed as: positioning repeatability, tuning requirement according to different wind speeds for different seasons, and the mass changing via different scientific equipments added to the telescope. This study is aimed at resolving these issues for ground based small alt-azimuth telescopes. Establishing of a set and forget system is performed by designing an adaptive controller. Motor dynamics are taken into consideration for a realistic mathematical model. The Wind-Gust model that consists of a sum of sinusoidal disturbances with unknown phase, amplitude and frequency is used for the wind model. The purposed controller cancels the disturbance effects on the plant while operational positioning and also the makes the plant insensitive to mass changes. The Lyapunov approach is utilised when proving the asymptotic stability. The proposed controller’s success is illustrated with thorough numerical evaluation.The authors would like to thank the technical guidance and funding support of Isik University, Center for Optomechatronics Research and Application (OPAM),and Ataturk University Center for Astrophysical Application and Research (ATASAM). The author(s) received no financial support for the research, authorship, and/or publication of this article.Publisher's Versio

Investigating the Faculty and the Students' Technology Acceptance based on the Development of Cloud-Based Course Management System Software

Bu çalışmanın amacı Bulut Bilişim ve Web 2.0 teknolojileri kullanılarak DETSİS (Ders Etkinlik Takip Sistemi) ders yönetim sistemi yazılımı geliştirilerek bu yazılıma yönelik öğretim elemanı ve öğrencilerin teknoloji kabullerinin incelenmesidir. Araştırmada nicel ve nitel veri toplama teknikleri kullanılmıştır ve araştırma verileri, 2013-2014 eğitim-öğretim yılında Trakya Üniversitesi Eğitim Fakültesinde öğrenim görmekte olan 410 öğrenci ve aynı fakültede görev yapmakta olan 12 öğretim elemanından elde edilmiştir. Nicel veriler Teknoloji Kabul Ölçeği ve DETSİS Yazılım Değerlendirme Ölçeği kullanılarak; öğretim elemanlarının teknoloji kabulleri ise nitel veri toplama tekniklerinden olan yarı yapılandırılmış görüşmeler yoluyla elde edilmiştir. Elde edilen bulgular, öğretim elemanlarının ve öğrencilerin DETSİS yazılımına yönelik kabullerinin yüksek seviyede olduğunu ortaya çıkarırken, DETSİS' e yönelik kabullerinde Bulut Bilişim ve Web 2.0 olanaklarının olumlu etkisinin bulunduğunu göstermektedir.In this study, DETSİS, a course management system, has been developed using Cloud Computing and Web 2.0 technologies and it was aimed to investigate the faculty and the students' technology acceptance for this software. The research data were collected through the quantitative and qualitative data collection techniques from 410 students who are studying at the Trakya University Faculty of Education in the 2013-2014 academic year and 12 faculty members who are working in the same faculty. While quantitative data were collected with the use of the Technology Acceptance Model (TAM) and DETSİS Software Evaluation Scale, technology acceptance of the faculty were obtained through semi-structured interviews with qualitative data collection techniques. The findings revealed that, teaching staff and students have a high level of acceptance for DETSİS, indicating Cloud Computing and Web 2.0 capabilities had a positive impact of acceptance for DETSİS

Dejeneratif spondilolistezis, spinal stenoz, lomber kompresyon fraktürü olan yüksek riskli hastalarda spinal anestezi ile posterior lomber stabilizasyon cerrahisi

AIm: Spinal anesthesia is an appropriate technique for lumbar spine surgeries of two to three hours duration. The aim of this study is todocument our experience on spinal anesthesia administered to the patients with degenerative lumbar spine.Ma terIal and Methods: A total of 497 patients underwent spinal stabilization surgery with spinal anesthesia for degenerative lumbarspinal disorders in an 8-year period. Spinal anesthesia was performed at the L3-L4 or L4-L5 level and subarachnoid block was achieved with15 mg of 0.5% plain bupivacaine with 2 µg of fentanyl and 0.2 mg of epinephrine. There was no failure of anesthesia. The patients wereclosely monitored for complications associated with the SA technique and especially hypotension and bradycardia but no gross alterations incardiovascular stability were noted.Results: Among the 497 patients, 139 were male and 358 were female with a median age of 51 years. The average anesthesia durationwas 130 minutes and the average operative time was 85 minutes. In the postoperative period 36 patients has nausea (7.2%) and 18 of themhad vomiting (3.6%) that required one dose of antiemetic. No spinal headache was observed and 36 (7.2%) patients complained of urinaryretention. All recovered with urinary cannulation within 24 hours. No respiratory complication occurred and no patient died.ConclusIon: Spinal anesthesia is a safe and effective procedure for the lumbar spinal stabilization surgery, especially in high-riskpatients.Proper precautions should be taken in order to achieve an effective anesthesia for these operations