15,756 research outputs found

    Multiquark Hadrons - A New Facet of QCD

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    I review some selected aspects of the phenomenology of multiquark states discovered in high energy experiments. They have four valence quarks (called tetraquarks) and two of them are found to have five valence quarks (called pentaquarks), extending the conventional hadron spectrum which consists of quark-antiquark (qqˉ)(q\bar{q}) mesons and qqqqqq baryons. Multiquark states represent a new facet of QCD and their dynamics is both challenging and currently poorly understood. I discuss various approaches put forward to accommodate them, with emphasis on the diquark model.Comment: 27 pages, 8 figures, 6 tables, to be published in the proceedings of the 14th. Regional Conference on Mathematical Physics, Nov. 9-14, 2015, Quaid-i-Azam University, Islamabad, Pakista

    Corporate governance structure and firm performance : empirical evidence from Brusa Malaysia, Kuala Lumper

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    The issue of corporate governance has been emerging as important phenomena that has been searched extensively both in developed countries due to its strategic impact on the monitoring of management activities and firms&rsquo; performance. Yet little attempt has been made in developing countries like Malaysia to ascertain what constitute corporate governance and its impact on firm\u27s performance. Therefore, this study aims at examining the structure of the corporate governance and its impact on firm&rsquo;s performance. This study is based on 100 firms, which are the component of the Composite Index (CI) serve as market barometer. This study employs cross-sectional annual multiple regression model to examine, what constitutes the corporate governance structure and its impact on performance of the firm. The analysis was based on annual regression over 5 years period from 1997 through 2001. Three different blend of surrogate for corporate governance were developed for good corporate governance structure. These are the independent non-executive (outside) directors, audit committee and remuneration committee. To isolate the size effect from the impact of corporate governance structure on firm&rsquo;s performance, firm&rsquo;s size was also included are variable in the model. The ratio of net income before tax to total asset is used as a surrogate for firm&rsquo;s performance. Evidence from the study indicates that there is partial relation between corporate governance structure and corporate performance. The presence of both audit and remuneration committee serves as an important monitoring device to control management activities that lead to increase firm\u27s performance. While on average, the presence of independent nonexecutive directors does not provide any significant explanation for the firm\u27s performance. However, the firm size appears to have significant impact on corporate performance.<br /

    Hair histology as a tool for forensic identification of some domestic animal species

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    Animal hair examination at a criminal scene may provide valuable information in forensic investigations. However, local reference databases for animal hair identification are rare. In the present study, we provide differential histological analysis of hair of some domestic animals in Upper Egypt. For this purpose, guard hair of large ruminants (buffalo, camel and cow), small ruminants (sheep and goat), equine (horse and donkey) and canine (dog and cat) were collected and comparative analysis was performed by light microscopy. Based on the hair cuticle scale pattern, type and diameter of the medulla, and the pigmentation, characteristic differential features of each animal species were identified. The cuticle scale pattern was imbricate in all tested animals except in donkey, in which coronal scales were identified. The cuticle scale margin type, shape and the distance in between were characteristic for each animal species. The hair medulla was continuous in most of the tested animal species with the exception of sheep, in which fragmental medulla was detected. The diameter of the hair medulla and the margins differ according to the animal species. Hair shaft pigmentation were not detected in all tested animals with the exception of camel and buffalo, in which granules and streak-like pigmentation were detected. In conclusion, the present study provides a first-step towards preparation of a complete local reference database for animal hair identification that can be used in forensic investigations.Comment: 8 pages, 3 Figure

    Generalized Uncertainty Principle as a Consequence of the Effective Field Theory

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    We will demonstrate that the generalized uncertainty principle exists because of the derivative expansion in the effective field theories. This is because, in the framework of the effective field theories, the minimum measurable length scale has to be integrated away to obtain the low energy effective action. We will analyze the deformation of a massive free scalar field theory by the generalized uncertainty principle, and demonstrate that the minimum measurable length scale corresponds to a second more massive scale in the theory, which has been integrated away. We will also analyze CFT operators dual to this deformed scalar field theory, and observe that scaling of the new CFT operators indicates that they are dual to this more massive scale in the theory. We will use holographic renormalization to explicitly calculate the renormalized boundary action with counterterms for this scalar field theory deformed by the generalized uncertainty principle and show that the generalized uncertainty principle contributes to the matter conformal anomaly.Comment: 15 pages, no figures, Accepted for Publication in Physics Letters