Analogue Special and General Relativity by Optical Multilayer Thin Films: The Rindler Space Case

In this paper, to obtain an analogy between the curved spaces and the linear optics, we expand the idea of Ref.[1, 2] to the multilayer films. We investigate efects of thickness and index of refraction of the films on the Lorentzian transformations. In addition, by using the multilayer films, we suggest very simple experimental set-up which can serve as an analogue computer for testing special relativity. Finally, we draw an analogy between the Rindler space, as an example of the curved spaces, and a suitable multilayer film.Comment: 5 Figure

Lorentzian Wormholes in the Friedman-Robertson-Walker Universe

The metric of some Lorentzian wormholes in the background of the FRW universe is obtained. It is shown that for a de Sitter space-time the new solution is supported by Phantom Energy. The wave equation for a scalar field in such backgrounds is separable. The form of the potential for the Schr\"{o}dinger type one dimensional wave equation is found.Comment: 7 page

MATHEMATICAL MODELING AND NUMERICAL SIMULATION OF HEAT TRANSFER FROM ISOLATED OBJECTS

In the area of heat transfer, like other fields of science and engineering, full- and semi-analytical solutions of elementary problems are regarded as invaluable resources that can be used to identify relevant dimensionless parameters, to obtain basic insights into the phenomena under consideration, to quickly quantify the effects of key factors, and, ultimately, to pave the way for understanding more complex problems arising in practice. These solutions can also serve as excellent benchmarks for calibrating experimental setups and validating numerical techniques. In this dissertation, we theoretically study three classical heat transfer problems, with the ultimate goal of deriving analytical or approximate expressions for the Nusselt number (denoted by Nu), which is a key dimensionless parameter that quantifies the transfer of heat to and from a surface. First, we consider heat transfer by conduction from oblate spheroidal and bispherical surfaces into a stationary, infinite medium. The surfaces are presumed to maintain a constant heat ux. Assuming steady-state condition and uniform thermal conductivity, we analytically solve the Laplace equation for the temperature distribution and discuss the challenge of dealing with the Neumann (uniform flux) versus more convenient Dirichlet (isothermal) boundary condition. The solutions are obtained in boundary-fitting coordinate systems using the method of separation of variables and eigenfunction expansion. And, exact expressions for the average Nusselt number are presented along with their approximations. Next, we examine forced convection heat transfer from a single particle in uniform laminar flows. Asymptotic limits of small and large Peclet numbers (denoted by Pe) are considered. For Pe \u3c\u3e 1 and small or moderate Reynolds numbers. Specific results are given for the heat transfer from spheroidal particles in Stokes ow. Finally, we revisit the problem of steady-state heat transfer from a single particle in a uniform laminar ow with the assumption that the thermal conductivity of the fluid changes linearly with the temperature. We use a combination of asymptotic and scaling analyses to derive approximate expressions for the Nusselt number of arbitrarily shaped particles. The results cover the entire range of the Peclet number. We find that, for a constant temperature boundary condition and fixed geometry, the Nusselt number is essentially equal to the product of two terms, one of which is only a function of Pe while the other one is nearly independent of Pe and mainly depends on the proportionality constant of the conductivity-temperature relation. We also show that, in contrast, when a uniform heat flux is imposed on the surface of the particle, the Nusselt number can be estimated as a summation of a Pe-dependent piece and one that solely varies with the proportionality constant

Towards a Quantum-Like Cognitive Architecture for Decision-Making

We propose an alternative and unifying framework for decision-making that, by using quantum mechanics, provides more generalised cognitive and decision models with the ability to represent more information than classical models. This framework can accommodate and predict several cognitive biases reported in Lieder & Griffiths without heavy reliance on heuristics nor on assumptions of the computational resources of the mind

Improving the oxidation resistance of diboride-based ceramics

Oxidation behavior has restricted the development of ZrB₂-based ceramics for aerospace and hypersonic flight vehicles applications. The research presented in this dissertation focuses on the effect of transition metal (TM) additives on oxidation behavior of ZrB₂ ceramics. In the first stage of the research, the effect of Nb additions on the morphology of the oxide particles and stability of the protective B₂O₃ glassy layer, which formed on the top surface during oxidation, was investigated. Addition of Nb increased the thickness of the glassy layer and, as a result, improved the oxidation resistance of ZrB₂ after oxidation at 1500⁰C. Next, the oxidation behavior of nominally pure ZrB₂ and (Zr,W)B₂ after oxidation at temperatures ranging from 800 to 1600⁰C was studied. Two oxidation stages before and after significant evaporation of B₂O₃ at about 1100⁰C were recognized for nominally pure ZrB₂. Higher stability for the WO₃-B₂O₃ glassy layer compared to pure B₂O₃ resulted in a shift in the onset of the second oxidation regime toward higher temperatures for (Zr,W)₂ specimens and resulted in higher oxidation resistance for (Zr,W)B₂ compared to nominally pure ZrB₂. In the third stage of the research, the effects of TM-oxides such as WO₃, Nb₂O₅, or ZrO₂ on weight loss and structure of B₂O₃ glasses was studied. Thermogravimetric analysis performed on (TM-oxide)-B₂O₃ glasses indicated that TM-oxide additions reduced the evaporation of B₂O₃. Since no change in the structure of the glasses was detected, it was concluded that the increased stability of (TM-oxide)-B₂O₃ glasses compared to pure B₂O₃ was due to the lower activity of B₂O₃ in (TM-oxide)-B₂O₃glasses. Finally, comparison of the effects of W, Mo, or Nb on oxidation behavior of ZrB₂ at 1600⁰ showed that Mo and Nb were the most effective additives for improving the oxidation resistance of ZrB₂ --Abstract, page iv

B2B unfair trade practices and EU competition law

cited By 0EU competition law appears to interpret fairness in B2B trade relations as "equal opportunities to trade" for market actors. A positive and pragmatic inquiry into the relevant regulations, cases and doctrines support that approach. This contribution suggests a new definition for these practices under EU competition law. Accordingly, any trade practice representing supremacy in bargaining power - usually dominance - and distorting the equal opportunity to trade of one or more trading partners could be conceived as unfair trade practices (UTPs) under EU competition law. Thus, these practices restrict competition according to EU competition law. Indeed, the EU Commission, Parliament and many Member States have emphasized the restrictive effects of UTPs even when practised by non-dominant undertakings. UTPs could include all kinds of trade practices toward trading partners, regardless of the industry and environment in which they occur, whether online or offline. This definition can also relieve competition lawyers from inefficient exploitative/exclusionary abusive conduct divisions.© 2018 Informa UK Limited, trading as Taylor & Francis Group.Peer reviewe

The impact of social identity of brand on brand loyalty development

During the past few years, there have been increasing discussions on the impact of brand in business units. Many researchers have concluded that the best way to increase sales is to introduce the brand in society. In this study, we consider the impact of brand identity on increasing product loyalty in one of Iranian dairy products. The proposed study is implemented in city of Tehran by choosing 475 people. The proposed model is analyzed using structural equation model and factor analysis. The results indicate that there is a direct positive relationship between brand and loyalty and a powerful brand could help setup a long-term relationship between customer and firm, which leads to brand loyalty. In other words, brand identity influences perception value, customer satisfaction, brand trust while perception value influences customer satisfaction and brand trust. In addition, customer satisfaction influences brand trust, brand trust influences customer loyalty and finally brand identity indirectly influences customer loyalty

Brain Magnetic Resonance Imaging Findings in Developmentally Delayed Children

Background. Developmental disorders are failure or inability to acquire various age-specific skills at expected maturational age, which affects about 5–10% of preschool children. One of the most important methods for evaluation of developmentally delayed children is neuroimaging, especially, brain magnetic resonance imaging (MRI) that provides useful information regarding brain tissue structures and anomalies. Method and Material. In this study, hospital records of 580 developmentally delayed children (aged 2 months to 15 years) who admitted in pediatric ward of Golestan Hospital from 1997 to 2009 were selected. Information such as age, MRI findings were collected in the questionnaire and statistically analyzed. Results. Total, 580 children including 333 males (57.4%) and 247 females (42.6%) were studied. Abnormal brain MRI was observed in 340 (58.6%) cases (204 Males, 136 females). The finding includes nonspecific in 38 (6.6%), congenital and developmental anomalies of brain in 39 (6.7%), recognizable syndromes in 3 (0.5%), neurovascular diseases or trauma in 218 (37.6%), and metabolic or neurodegenerative diseases in 42 (7.2%) cases. Conclusion. Because 60% of all study groups showed abnormal brain MRI, using this method could be effective in diagnosis, management, and almost prognosis determination processes

Anterior Cervical Foraminotomy: Short Term Outcomes In Patients With Isolated Cervical Radiculopathy

Intro: Anterior cervical foraminotomy (ACF) is a novel approach involving direct decompression of nerve from an offending agent without fusion. Historically, several anterior and posterior approaches were utilized to treat cervical radiculopathy. Anterior cervical discectomy necessitates fusion and is subject to adjacent segment disease as well as loss of ROM. Posterior laminoforaminotomy seldom allows for removal of disc fragment and is associated with higher postoperative pain. Methods: Between May 2010 and March 2013, 16 patients with one or two level cervical spondylosis with radiculopathy without myelopathy who failed conservative therapies such as anti-inflammatory medications, physical therapy or injections underwent anterior foramintomy. All patients underwent pre-operative MRI that confirmed either a “soft” disc, spondylytic spur or a combination of the two. 15 of the 16 patients had no prior surgery. One had a prior ACDF at an adjacent level. All patients were assessed at two weeks for a wound check and again at two months. The visual analog score was used to assess their pre-operative and post-operative pain symptoms. A paired t test was used to compare pre- and post-operative VAS. Significance was accepted at a value of p \u3c 0.05. Results: The average VAS pre-operatively was 7.75 and the average VAS score post-operatively was 1.1 (p value 0.02). All but two patients with weakness returned to normal strength. Of the 13 patients that had pre-operative parasthesias only five had residual symptoms, all of which they described as improved compared to their pre-operative symptoms. OR times ranged from 97-174 minutes with a mean of 124.6 minutes. Conclusion: ACF is an alternative to standard posterior and anterior cervical operations for the treatment of cervical radiculopathy. In our study patients had good short term outcomes, however long term data needs to be obtained. ACF is a motion preserving operation and comparative data should be obtained between cervical disc arthroplasty and ACF