5,603 research outputs found

    SU(N) Coherent States

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    We generalize Schwinger boson representation of SU(2) algebra to SU(N) and define coherent states of SU(N) using 2(2N11)2(2^{N-1}-1) bosonic harmonic oscillator creation and annihilation operators. We give an explicit construction of all (N-1) Casimirs of SU(N) in terms of these creation and annihilation operators. The SU(N) coherent states belonging to any irreducible representations of SU(N) are labelled by the eigenvalues of the Casimir operators and are characterized by (N-1) complex orthonormal vectors describing the SU(N) manifold. The coherent states provide a resolution of identity, satisfy the continuity property, and possess a variety of group theoretic properties.Comment: 25 pages, LaTex, no figure

    Fauna ediacárica del Grupo de Jodhpur (Supergrupo de Marwar) en la ciudad de Jodhpur, al oeste de Rajasthan, India: Implicación para la selección de posibles sitios geopatrimoniales

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    The Ediacaran fossil record of the Jodhpur Group in the surroundings of Jodhpur city, western Rajasthan, is revised. Their best exposures are considered as potential Geoheritage sites. A specific protection from quarrying is envisaged.Se revisa el registro fósil ediacárico del Grupo de Jodhpur en los alrededores de la ciudad de Jodhpur, al oeste de Rajastán. Sus mejores afloramientos son considerados como sitios potenciales de Geopatrimonio. Se prevé una protección específica contra la explotación de sus canteras

    Drug development: Lessons from nature.

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    Natural products have been acknowledged for numerous years as a vital source of active ingredients in therapeutic agents. In particular, the use of active ingredients derived from plants for use in microbial natural products have long been used before the dawn of modern medicine. From ancient times, the efficacy of natural products has been associated with the chemistry, biochemistry and synthetic activities of natural products. Thus, with scientific advancement in modern molecular and cellular biology, analytical chemistry and pharmacology, the unique properties of these natural products are being harnessed in order to exploit the chemical and structural diversity and biodiversity of these types of products in relation to their therapeutic effect. Often, new molecules of interest in drug design units focus on the rearrangement of chemical entities or structural isomers of naturally occurring products in order to generate new molecules; these may be formulated into clinically useful therapies

    Discourses Of Prejudice In The professions: The Case Of Sign Languages

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    There is no evidence that learning a natural human language is cognitively harmful to children. To the contrary, multilingualism has been argued to be beneficial to all. Nevertheless, many professionals advise the parents of deaf children that their children should not learn a sign language during their early years, despite strong evidence across many research disciplines that sign languages are natural human languages. Their recommendations are based on a combination of misperceptions about (1) the difficulty of learning a sign language, (2) the effects of bilingualism, and particularly bimodalism, (3) the bona fide status of languages that lack a written form, (4) the effects of a sign language on acquiring literacy, (5) the ability of technologies to address the needs of deaf children and (6) the effects that use of a sign language will have on family cohesion. We expose these misperceptions as based in prejudice and urge institutions involved in educating professionals concerned with the healthcare, raising and educating of deaf children to include appropriate information about first language acquisition and the importance of a sign language for deaf children. We further urge such professionals to advise the parents of deaf children properly, which means to strongly advise the introduction of a sign language as soon as hearing loss is detected

    XMM-Newton observations of SDSS J143030.22-001115.1: an unusually flat spectrum AGN

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    We present XMM observations of the AGN SDSS 1430-0011. The low S/N spectrum of this source obtained in a snap shot Chandra observation showed an unusually flat continuum. With the follow up XMM observations we find that the source spectrum is complex; it either has an ionized absorber or a partially covering absorber. The underlying power-law is in the normal range observed for AGNs. The low luminosity of the source during Chandra observations can be understood in terms of variations in the absorber properties. The X-ray and optical properties of this source are such that it cannot be securely classified as either a narrow line Seyfert 1 or a broad line Seyfert 1 galaxy.Comment: Submitted to A
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