831 research outputs found

    On black holes in heterotic braneworlds

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    We explore the problem of braneworld black holes in the heterotic braneworld scenario of Lukas, Ovrut, Stelle and Waldram (LOSW). We show that black string solutions are unstable, and demonstrate some unusual asymptotics in the linearized metric. We also solve the fully coupled brane and bulk Einstein equations, finding an exact, though singular, solution which corresponds to a brane black hole in which the branes spike apart at the Schwarzschild radius.Comment: 20 pages, 3 figure

    Multi-layer feed forward neural networks for foreign exchange time series forecasting

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    This dissertation examines the forecasting performance of multi-layer feed forward neural networks in modeling five weekly foreign exchange rates: Australian Dollars/U.S. Dollars (AUS/USD), Euro/U.S. Dollar (EUR/USD), Swiss Franc/U.S. Dollar (CHF/USD), British Pound sterling/U.S. Dollars (GBP/USD), and Japanese Yen/U.S. Dollars (JPY/USD). There are five objectives to accomplish. The first is to determine the key modeling factors that should be considered in topology determination. The second is to compare the performances of Genetic Algorithm (GA) and Modified Tabu Search (TS) in choosing the topology for Neural Networks (NN) implementation. The third is to investigate the suitable learning algorithm for NNs for time series forecasting by comparing Back Propagation (BP) with GAs and TS. The fourth is to conduct computational studies for multi-step ahead forecasting for GBP/USD and EUR/USD, as well as to study other accuracy forecasting issues. The last is to study the implementation of multivariate time series forecasting using NNs.;The results of the experiments performed indicate that one should examine the correct topology, especially the three most important factors (number of input nodes, hidden nodes, learning rate) prior to using NNs for time series forecasting.;The comparison performance of topology suggested using GA, TS, and benchmark led to the conclusion that neither GA nor TS is guaranteed to provide better results, especially in terms of percentage of true directional changes (DIR). However, if there is no prior knowledge of the problem, GA searches for topology determination are favored and provide reasonably good performances. GA is also preferred for NN training. Compared to BP, GA guarantees better performance in terms of Mean of Absolute Percentage Error (MAPE) and, most of the time, performs better in terms of Mean of Square Error (MSE).;Caution should be taken in adopting the results, since the study of time periods indicated that the best topology for forecasting a specific foreign exchange is data specific ; hence the best for a certain period is not always the best to forecast other periods. However, the chosen topology is reasonably useful for up to three steps ahead forecasting.;The trivariate time series, which incorporate interest rates of the two countries involved, did improve the results. Multivariate time series forecasts for monthly JPY/USD, as well as for monthly EUR/USD, produced a higher level of success than the one achieved in the previous experiment. The NNs were programmed using MATLABRTM

    ANALISIS PENGARUH KARAKTERISTIK CORPORATE GOVERNANCE DAN STRUKTUR KEPEMILIKAN SAHAM TERHADAP KINERJA PERUSAHAAN (Studi Empiris pada Perusahaan Manufaktur yang Terdaftar Tahun 2010- 2014 di Bursa Efek Indonesia)

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    The purpose of this study is to analyze the effect arising from the characteristics of corporate governance by proxy size of the board of directors, the independence of the board of commisioners and the size of the audit committee with the ownership structure with a proxy family ownership, institutional ownership, public ownership and foreign ownership of the company’s performance. Dependent variabel in this research is the company’s performance measured by Tobin’s Q. Total sample in this study are 44 companies listed in Indonesia Stock Exchange during 2010-2014. The sampling method used is purposive sampling method with predetermined criteria. This study uses multiple reggresion analysis to examine the effect of the characteristic of the corporate governance and ownership structure on company’s performance. The results of this study indicate that the size of the board of directors, audit committees and public ownership positively affects company performance measured by Tobin's Q. But the independence of the board of commissioners, family ownership, institutional ownership and foreign ownership ha s no effect on company performance measured by Tobin's

    Navigating the Murk: Ethical and Practical Considerations for the Surgical Treatment of the Sacroiliac Joint Syndrome

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    The field of spine surgery has many controversies. The surgical treatment of the sacroiliac (SI) joint is, too, fraught with debate. The diagnosis of painful SI joints is currently limited to relief following “diagnostic” injections and pain generated from a suite of clinical maneuvers. Diagnoses of SI joint dysfunction are dependent entirely on patient-reported responses to provocative maneuvers and invasive procedures. There is a glaring lack of objective radiographic and objective physical examination findings for this syndrome. The evidence for treatment, and specifically for the surgical treatment of the SI joint is reviewed and critiqued. Although the surgical techniques are simple, consensus is elusive for both indication and optimal technique. Ethical principles for surgical innovation and practical considerations for the treatment of the SI joint syndrome are discussed at length. Discussed as well are key points to consider when providing informed consent to a patient before proceeding with surgical intervention for this procedure and diagnosis. Spine surgery is a field with considerable regional variation in practice. Even today, the precise indications for arthrodesis, extent, and approach, remain frequently debated; however, as much conversation takes place surrounding lumbar surgery, even more confusion, bias, opinion, and deliberation exists when surgical treatment of the SI joint is considered. This chapter discusses the unique challenges associated with the SI joint and provides practical considerations for the treatment thereof.Open access articleThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

    Perception Of Islanders Towards Promotion Of Island Tourism In The State Of Goa - An Empirical Study

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    Island Tourism refers to the phenomenon of the development of tourism on an island that advances the establishment of family guesthouses, corporate hotels, and other related commercial areas, as well as an integration of the island\u27s scenic spots and urban developments, which in turn can influence the island\u27s local population growth, environmental improvement, completion of facilities, and functional upgrading (Jun Yung, 2016) It\u27s not just the beaches that make Goa an absolute paradise, there are a few Islands in complete isolation that offers some much-needed solace away from all the humdrum from the beaches. Island tourism in Goa is one such tourism which can reduce the stress on Goa\u27s ecology with its unique flora and fauna, exotic coral reefs, marine life and special geographic features. The objective of the present study is to analyse the perception of Islanders in Goa towards Promotion of Island Tourism in the State of Goa. This was analysed using Exploratory Factor Analysis and Multiple Regression Analysis. The present study helps create the ground work for community involvement in Tourism. The study reveals that there is a negative perception of Islanders towards Island Tourism in the state of Goa

    A galU mutant of francisella tularensis is attenuated for virulence in a murine pulmonary model of tularemia

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    <p>Abstract</p> <p>Background</p> <p>A number of studies have revealed that <it>Francisella tularensis </it>(FT) suppresses innate immune responses such as chemokine/cytokine production and neutrophil recruitment in the lungs following pulmonary infection via an unidentified mechanism. The ability of FT to evade early innate immune responses could be a very important virulence mechanism for this highly infectious bacterial pathogen.</p> <p>Results</p> <p>Here we describe the characterization of a <it>galU </it>mutant strain of FT live vaccine strain (LVS). We show that the <it>galU </it>mutant was highly attenuated in a murine model of tularemia and elicited more robust innate immune responses than the wild-type (WT) strain. These studies document that the kinetics of chemokine expression and neutrophil recruitment into the lungs of mice challenged with the <it>galU </it>mutant strain are significantly more rapid than observed with WT FT, despite the fact that there were no observed differences in TLR2 or TLR4 signaling or replication/dissemination kinetics during the early stages of infection. We also show that the <it>galU </it>mutant had a hypercytotoxic phenotype and more rapidly induced the production of IL-1β following infection either <it>in vitro </it>or <it>in vivo</it>, indicating that attenuation of the <it>galU </it>mutant strain may be due (in part) to more rapid activation of the inflammasome and/or earlier death of FT infected cells. Furthermore, we show that infection of mice with the <it>galU </it>mutant strain elicits protective immunity to subsequent challenge with WT FT.</p> <p>Conclusions</p> <p>Disruption of the <it>galU </it>gene of FTLVS has little (if any) effect on <it>in vivo </it>infectivity, replication, or dissemination characteristics, but is highly attenuating for virulence. The attenuated phenotype of this mutant strain of FT appears to be related to its increased ability to induce innate inflammatory responsiveness, resulting in more rapid recruitment of neutrophils to the lungs following pneumonic infection, and/or to its ability to kill infected cells in an accelerated fashion. These results have identified two potentially important virulence mechanisms used by FT. These findings could also have implications for design of a live attenuated vaccine strain of FT because sublethal infection of mice with the <it>galU </it>mutant strain of FTLVS promoted development of protective immunity to WT FTLVS.</p
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