Metformin reduces ovarian ischemia reperfusion injury in rats by improving oxidative/nitrosative stress

Objective: To assess the preventive role of metformin on rat ovarian ischemia reperfusion injury. Materials and methods: Forty rats were divided equally into five groups; Group 1: sham, Group 2: surgical control with 3-hr torsion and detorsion, Group 3: 50 mg/kg p.o. metformin 30 min before 3-hr torsion, Group 4; metformin just after detorsion, Group 5; metformin 30 min before torsion and just after detorsion. Bilateral ovaries and blood sample were obtained seven days after detorsion for biochemical and histopathological evaluation. Results: Ovarian tissue total anti-oxidant status (TAS) levels were significantly increased in group 4 when compared to group 1, 2 and 3 (all p < 0.01). In addition, there was a significant decrease in tissue oxidative stress index (OSI) level in group 4 with respect to group 2 (p < 0.01). Moreover, serum levels of OSI were significantly higher in group 2 with respect to group 1 and 5 (both p < 0.05). Similarly, there was significant increase in serum levels of peroxynitrite in group 2 as compared to serum levels in group 3 and 5 (p < 0.01 and 0.05, respectively). Furthermore, there were significant decrease in histopathological scores metformin and sham groups when compared to rats in the control group (Group 2). Conclusion: Metformin reduces ischemia reperfusion injury in rat torsion detorsion model by improving histopathological and biochemical findings including TAS, OSI and peroxynitrite

Stackelberg versus Cournot oligopoly with private information

We compare an n-firm Cournot model with a Stackelberg model, where n-firms choose outputs sequentially, in a stochastic demand environment with private information. The expected total output, consumer surplus, and total surplus are lower, while expected price and total profits are higher in the Stackelberg perfect revealing equilibrium than in the Cournot equilibrium. These rankings are the opposite of the rankings of prices, total output, surplus, and profits under perfect information. We also show that the first n?1 firms’ expected profits form a decreasing sequence from the first to the (n?1)st in the Stackelberg game. The last mover earns more expected profit than the first mover if n?4, or the ratio of the signals’ informativeness to the prior certainty is sufficiently low. Lastly, there is a discontinuity between the Stackelberg equilibrium of the perfect information game and the limit of Stackelberg perfect revealing equilibria, as the noise of the demand information of firms vanishes to zero at the same rate. We provide various robustness checks for the results when the precision of signals are asymmetric, there is public information or cost/quality uncertainty, or the products are differentiated

Three Determinant Evaluations

By means of matrix decompositions, three determinants with their entries being binomial sums are evaluated in closed forms. Ten remarkable examples are illustrated as propositions, which present determinant identities about binomial coefficients and quotients of rising factorials, as well as orthogonal polynomials named after Hermite, Laguerre and Legendre

The Success of the Deferred Acceptance Algorithm Under Heterogenous Preferences with Endogenous Aspirations

In this paper, we consider a one-to-one matching model with two phases; an adolescence phase where individuals meet a number of dates and learn about their aspirations, followed by a matching phase where individuals are matched according to a version of Gale and Shapley’s (Am Math Mon 69:9–15, 1962) deferred acceptance (DA) algorithm. Using simulations of this model, we study how the likelihoods of matching and divorce, and also the balancedness and the speed of matching associated with the outcome of the DA algorithm are affected by the size of correlation in the preferences of individuals and by the frequency individuals update their aspirations in the adolescence phase

A literature review of biosensors for multiple sclerosis: Towards personalized medicine and point-of-care testing

Multiple sclerosis (MS) is a chronic neuroinflammatory disease of the central nervous system that leads to severe motor and sensory deficits in patients. Although some biomolecules in serum or cerebrospinal fluid have been suggested as biomarkers for MS diagnosis, following disease activity and monitoring treatment response, most of these potential biomarkers are not currently in clinical use and available for all patients. The reasons behind this are generally related to insufficient robustness of biomarker or technical difficulties, high prices, and requirements for technical personnel for their detection. Point-of-care testing (POCT) is an emerging field of healthcare that can be applied at the hospital as well as at home without the need for a centralized laboratory. Biosensor devices offer a convenient means for POCT. A biosensor is a compact analytical device that uses a bioreceptor, such as an antibody, enzyme, or oligonucleotide, to capture the analyte of interest. The interaction between the analyte and the bioreceptor is sensed and transduced into a suitable signal by the signal transducer. The advantages of using a biosensor for detecting the biomolecule of interest include speed, simplicity, accuracy, relatively lower cost, and lack of requirements for highly qualified personnel to perform the testing. Owing to these advantages and with the help of innovations in biosensor development technologies, there has been a great interest in developing biosensor devices for MS in recent years. Hence, the purpose of this review was to provide researchers with an up-to-date summary of the literature as well as to highlight the challenges and opportunities in this translational research field. In addition, because this is a highly interdisciplinary field of study, potentially concerning MS specialists, neurologists, biomedical researchers, and engineers, another aim of this review was to bridge the gap between these disciplines

Control of visually guided braking using constant- τ and proportional rate

This study investigated the optical information and control strategies used in visually guided braking. In such tasks, drivers exhibit two different braking behaviors: impulsive braking and continuously regulated braking. We designed two experiments involving a simulated braking task to investigate these two behaviors. Participants viewed computer displays simulating an approach along a linear path over a textured ground surface toward a set of road signs. The task was to use a joystick as a brake to stop as close as possible to the road signs. Our results showed that participants relied on a weak constant-τ strategy (Bingham 1995) when regulating the brake impulsively. They used discrete τ values as critical values and they regulated the brake so as not to let τ fall below these values. Our results also showed that proportional rate control (Anderson and Bingham 2010, 2011) is used in continuously regulated braking. Participants initiated braking at a certain proportional rate value and controlled braking so as to maintain that value constant during the approach. Proportional rate control is robust because the value can fluctuate within a range to yield good performance. We argue that proportional rate control unifies the information-based approach and affordance-based approach to visually guided braking

Structural optimization of a composite launch tube of man portable air defense system

Savunma sanayi alanında üretilen parçalarda ağırlık kriteri her zaman büyük bir önem taşımıştır. Kompozit malzemeler ağırlık ve mekanik dayanım özellikleri açısından avantaj sağlaması sebebiyle savunma sanayisinde sıklıkla tercih edilen malzemeler arasında yer almaktadır. Bu tezde, geliştirilmekte olan ve taşınabilir hava savunma sisteminde kullanılan kompozit yapıdaki fırlatma tüpü için sonlu elemanlar modeli oluşturularak ağırlık eniyileme çalışması gerçekleştirilmiştir. Ağırlık kriterine ek kriterler de eklenerek gerçekçi bir çözüm elde edilmesi amaçlanmıştır. Tüm kriterler göz önünde bulundurularak maliyet formülasyonu oluşturulmuş ve optimum tasarıma ulaşılmıştır. Ağırlık eniyileme çalışmasında sarım kalınlıkları ve sarım açısı tasarım değişkenleri olarak belirlenmiştir. Kısıt fonksiyonu olarak Tsai-Wu hasar kriteri kullanılarak elde edilmiş olan emniyet katsayısı kullanılmıştır. Fırlatma tüpü sonlu elemanlar yöntemiyle modellenmiş, ısıl ve yapısal yükler fırlatma tüpü üzerine uygulanmıştır. Çözüm ağı yakınsama çalışması gerçekleştirilerek sonlu elemanlar yöntemi için uygun olan eleman boyutu belirlenmiştir. Sonraki aşamada, latin hiperküp örnekleme ve merkezi kompozit tasarım yöntemleri kullanılarak deney tasarımları oluşturulmuştur. Belirtilen deney tasarımları kullanılarak farklı vekil modeller ve farklı eniyileme yöntemleri ele alınmış ve ağırlık için eniyileme çalışması gerçekleştirilmiştir. İlgili çalışma, cam elyaf takviyeli epoksi matrisli malzeme (cam/epoksi), karbon elyaf takviyeli epoksi matrisli malzeme (karbon/epoksi) ve aramid elyaf takviyeli epoksi matrisli malzeme (aramid/epoksi) için gerçekleştirilmiş olup, kullanılan malzemeler ve yöntemler arasında karşılaştırma yapılmıştır. Üç malzeme için de latin hiperküp örnekleme yöntemi ile oluşturulan deney tasarımları kullanıldığında merkezi kompozit tasarıma göre daha hafif yapılar elde edildiği görülmüştür. Vekil model yöntemleri kıyaslandığında cam/epoksi ve karbon/epoksi malzeme için karesel polinom yanıt yüzey yöntemi, aramid/epoksi malzeme için ise Kriging yöntemi ile daha iyi sonuçlar elde edildiği gözlemlenmiştir. Eniyileme yöntemleri kıyaslandığında ise cam/epoksi malzeme için seçkisiz arama yönteminin, karbon/epoksi ve aramid/epoksi malzeme için ise genetik algoritma yönteminin daha iyi sonuçlar verdiği gözlemlenmiştir. Ağırlık eniyileme çalışması gerçekleştirildikten sonra ağrlık kriterine ek olarak bulunabilirlik, fiyat ve üretilebilirlik kriterleri de ele alınmıştır. Bu dört kriter önem sırasına göre yüzdesel olarak değerlendirilerek kullanılan kompozit malzemeler için maliyet formülasyonu oluşturulmuştur. Sonuç olarak, karbon elyaf takviyeli epoksi matrisli malzemenin fırlatma tüpü için maliyet etkin optimum tasarımı sağladığı gözlemlenmiştir.The weight criterion has always been of great importance for the parts produced in the defense industry. Composite materials are among the materials that are frequently preferred in the defense industry due to their advantages in terms of weight and mechanical strength. In this thesis, a weight optimization study was carried out by creating a finite element model for the composite launch tube that is being developed and used in the man portable air defense system. It is aimed to obtain a realistic solution by adding additional criteria to the weight criterion. Cost fomulation has been carried out by considering all criteria and optimum design has been achieved. In the weight optimization study, winding thicknesses and winding angle were determined as design variables. The safety factor obtained by using the Tsai-Wu damage criterion was used as the constraint function. The launch tube was modeled via finite element method and thermal and structural loads were applied on the launch tube. The suitable element size for the finite element method was determined by performing a mesh convergence study. In the next step, design of experiments were created using the latin hypercube sampling and central composite design methods. Using the specified design of experiments, different surrogate models and different optimization methods were discussed and optimization study for weight was performed. The study was carried out for glass fiber reinforced epoxy matrix material (glass/epoxy), carbon fiber reinforced epoxy matrix material (carbon/epoxy) and aramid fiber reinforced epoxy matrix material (aramid/epoxy). A comparison was made between the materials and the methods used. Using the design of experiments created with the latin hypercube sampling method for all three materials, it was observed that lighter structures were obtained compared to the central composite design method. When the response surface methods were compared, it was observed that better results were obtained with the quadratic polynomial response surface method for glass/epoxy and carbon/epoxy material, and with the Kriging method for aramid/epoxy material. When the optimization methods were compared, it was observed that the screening method for glass/epoxy material and the genetic algorithm method for carbon/epoxy and aramid/epoxy material gave better results. After the weight optimization study was carried out, availability, price and manufacturability criteria were also discussed in addition to the weight criteria. These four criteria were evaluated as percentages in order of importance and cost analysis was performed for the composite materials used. As a result, it has been observed that the carbon fiber reinforced epoxy matrix material provides the optimum cost effective design for the launch tube

A new type of Sylvester–Kac matrix and its spectrum

The Sylvester–Kac matrix, sometimes known as Clement matrix, has many extensions and applications throughout more than a century of its existence. The computation of the eigenvalues or even the determinant have always been challenging problems. In this paper, we aim the introduction of a new family of a Sylvester–Kac type matrix and evaluate the corresponding spectrum. As a consequence, we establish a formula for the determinant. © 2019, © 2019 Informa UK Limited, trading as Taylor & Francis Group

Development of mass sensitive sensor platform based on plasma polymerization technique: Quartz tuning fork as transducer

This paper describes a modification process of QTFs’ prongs with stable amine containing bilayer plasma polymer film and an application of quartz tuning fork (QTF) as a transducer for biomedical application. To produce stable amine containing film, first, we created plasma polymer films from hexane precursors. We then subjected those films to a second capping layer of ethylenediamine plasma polymer. The film was characterized by contact angle measurement, atomic force microscopy, and X-ray photoelectron spectroscopy. The effect of the interfacial structure onto stability was also analyzed in air. A model protein, BSA, sensing experiments were examined by measuring the shift in the resonance frequency of QTFs. The performance of the proposed sensor was investigated in terms of quality factor. These findings reveal that amine containing bilayer coated QTFs have the potential to be used in mass sensitive biosensor applications for future

Security analysis of mobile authenticator applications

İkili kimlik doğrulamanın uygulanması hesap ele geçirilme saldırılarına karşı şiddetle tavsiye edilen güvenlik mekanizmalarından bir tanesidir. İkili kimlik doğrulaması uygulamanın en yaygın yöntemlerinden bir tanesi bildiğiniz ve sahip olduğunuz faktörlerin bir araya getirilmesidir. Sahip olunan faktör için USB bellekler, SMS doğrulaması, mobil uygulamalar tarafından oluşturulan tek kullanımlık parola değerleri gibi seçeneklerimiz mevcuttur. Maliyet ve kolaylık nedenlerinden dolayı ikili kimlik doğrulama sürecini mobil uygulamalar tarafından üretilen tek kullanımlık parola değerleri ile dağıtmak daha yaygındır. Bununla birlikte kurcalamaya karşı dayanıklılık özelliğine sahip olan akıllı kartların aksine, saldırganlar akıllı telefonlara uzaktan ve ya fiziksel olarak erişebilir ve gizli tohum değerini okuyabilirler. Bu da mobil kimlik doğrulama uygulamaları için önemli bir güvenlik riskidir. Bu nedenle mobil kimlik doğrulama uygulamalarının bu bağlamda incelenmesi kritik önem taşımaktadır. Araştırmamızda on bir tane Android kimlik doğrulama uygulamasını inceledikten sonra bulgularımızı raporladık. Standart tersine mühendislik yöntemleri ve açık kaynak kodlu araçlar kullanarak beş uygulamada depolamadan ve yedi uygulamada bellekten gizli tohum değerini şifresiz metin olarak elde ettik.Deploying Two-Factor Authentication (2FA) is one of the highly-recommended security mechanism against account hijacking attacks. One of the common methods for 2FA is to bring something you know and something you have factors together. For the later we have options including USB sticks, smart cards, SMS verification, and one-time password values generated by mobile applications (soft OTP). Due to the cost and convenience reasons, deploying 2FA via soft OTPs is more common. However, unlike smart cards which have tamper resistance property, attackers can access smartphones remotely or physically so that they can fetch shared secret seed value - an important security risk for mobile authenticators. For this reason, it is critical to analyze mobile authenticator applications in this context. In this paper, we report our findings after analyzing eleven different Android authenticator applications. We report that we have fetched cleartext shared secret seed value from storage in five applications and from memory in seven applications using standard reverse engineering techniques and open-source tools