829 research outputs found

    Charged Scalar Pair Production in Strong-Field Photon-Photon Interaction

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    Following the pioneering work of H. Reiss [1], we provide a covariant calculation of the charged scalar particle pair production. The calculation is facilitated by the use of two-dimensional Bessel functions and light-font coordinates.Comment: 8 page

    Novel Edge States in Self-Dual Gravity

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    In contrast to the Einstein-Hilbert action, the action for self-dual gravity contains vierbeins. They are eleminated at the level of observables by an SL(2,C)SL(2,\mathbb{C}) gauge condition implied by the action. We argue that despite this condition, new "edge" or superselected state vectors corresponding to maps of the spheres S2S^2_{\infty} at infinity to SL(2,C)SL(2, \mathbb{C}) arise. They are characterised by new quantum numbers and they lead to mixed states. For black holes, they arise both at the horizon and the spatial infinity and may be relevant for the black hole information paradox. Similar comments can be made about the Einstein-Palatini action which uses vierbeins.Comment: 15 pages, reference added, some minor notational changes - no changes in conclusio

    Anomalous Defects and Their Quantized Transverse Conductivities

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    Using a description of defects in solids in terms of three-dimensional gravity, we study the propagation of electrons in the background of disclinations and screw dislocations. We study the situations where there are bound states that are effectively localized on the defect and hence can be described in terms of an effective 1+1 dimensional field theory for the low energy excitations. In the case of screw dislocations, we find that these excitations are chiral and can be described by an effective field theory of chiral fermions. Fermions of both chirality occur even for a given direction of the magnetic field. The ``net'' chirality of the system however is not always the same for a given direction of the magnetic field, but changes from one sign of the chirality through zero to the other sign as the Fermi momentum or the magnitude of the magnetic flux is varied. On coupling to an external electromagnetic field, the latter becomes anomalous, and predicts novel conduction properties for these materials.Comment: New material added. ReVTeX , 31 pgs., 4 figs.(uses epsf

    Leprosy of the larynx: A case report

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    Leprosy is an ancient deforming disease caused by Mycobacterium leprae, which is still poorly understood and often feared by the general public and even by some in the health care professions Fortunately, the outlook for patients has dramatically improved over the last three decades with the introduction of multi-drug treatment and management strategies that have somewhat diminished the stigma of this diagnosis. We report a rare case of leprosy of larynx. A 45 year old man presented with complaints cough, dyspnea and hoarseness since many years ago. Because of demonstration of acid fast bacilli in smear of his sputum, the diagnosis of tuberculosis was made and anti tuberculosis treatment was initiated. But he developed fever and his symptoms exacerbated. In examination there was a tender erythematous nodule on right supraclavicular region, loss of eyebrows and lashes and disseminated hyper and hypo pigmented cutaneous lesions on abdomen, thorax, back with normal chest x ray. Laryngoscopy to rule out laryngeal tuberculosis was done and granulomatous lesion was seen. Laryngeal and skin biopsy was performed which numerous acid fast bacilli, macrophages and foamy cells suggestive of lepromatous leprosy were demonstrated in both specimens. Treatment was started on multi bacillary regime of WHO multidrug therapy. In conclusion, this report highlights the importance of systemic involvement in lepromatous leprosy especially when the initial presentation is laryngitis or respiratory symptoms. Laryngeal leprosy may mistaken with tuberculosis laryngitis due to respiratory problems and existence of acid fast bacilli in respiratory secretions. © 2009 Tehran University of Medical Sciences. All rights reserved

    Antibiotic Resistance of Vibrio cholerae Isolates from Kashan, Iran

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    Aims: Cholera is an acute diarrheal disease that can lead to severe dehydration and death. Antibiotic resistance is a big challenge in infective disease like Cholera. The present study aimed to understand the characteristics and trends of antibiotic resistance of V. cholerae isolations in and around Kashan, Iran. Instrument & Methods: In this descriptive cross-sectional study, samples were gathered using census method from 1998 to 2013 in Kashan, Iran. 1132 fecal samples of patients with acute diarrhea and 237 samples of suspected water samples were taken. The serotypes and biotypes were determined by an enzymatic method. Antibiotic susceptibility test was performed by using Disk Diffusion Method. Data were analyzed using SPSS 23 software. Fisher-exact and Chi-square tests were used to compare the statistical parameters. Findings: 96 fecal samples (8.5) and 18 water samples (7.6) were positive for Vibrio cholerae. Non-agglutinating (Nag) isolates (75.4) were more common than serotype Inaba (13.2) and Ogawa (11.4). Nag serotypes were mostly resistant to cefixime (44) and ampicillin (33). In contaminated water samples also the most frequent cases were Nag serotype (50). Nag serotype showed 22.2 of resistance to ampicillin and nitrofurantoin. Conclusion: Vibrio cholerae isolates in Kashan, Iran, are highly resistant to antibiotics, especially Nag serotypes

    Composition, repellent and fumigant toxicity of Mentha longifolia essential oil on Tetranychus urticae and three predatory mites of the family phytoseiidae (Acari: Tetranychidae: Phytoseiidae)

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    The chemical composition of essential oil extracted from leaves of the medicinal plant Mentha longifolia (L.) Huds growing in Egypt, were determined through Gas Chromatography/Mass Spectrometry ( GC/MS). The analyses revealed that the major component of M. longifolia was Monterpene ketone (piperitone oxide). Mentha longifolia was potent for the pest Tetranychus urticae Koch with a significant increase in repellency. In addition, it exhibited strong oviposition deterrence to the pest based on a 99.4% reduction of the total number of eggs on leaf discs treated with the oil. The LC50 values of M. longifolia against eggs, nymphs and females of T. urticae by fumigant application, were 2.95, 3.47, 3.74 μL / L, while the LC90 values were 8.99, 9.41, 11.01 μL/ L, respectively. The toxicity of M. longifolia oil by fumigant application to females and eggs of 3 predatory phytoseiid mites was tested. Neoseiulus californicus (McGregor) is extremely insusceptible to M. longifolia oil than the pest T. urticae and both phytoseiid mites, Neoseiuls barkeri (Hughes) and Typhlodromips swirskii (Athias Henriot) under laboratory conditions. When both stages of tested predatory mites, exposed to fumigant of LC50 and LC90 μL/L values reported on T. urticae, female’s mortality of N. californicus was lesser than that reported on N. barkeri and T. swirskii. These show that the fumigant toxicity of M. longifolia oil has the highest lethal activity to the pest T. urticae and the least to the predatory mite N. californicus. Results indicated that the mode of delivery of the essential oil was largely a result of action in the vapor phase via respiratory system. Data was suggested that M. longifolia oil have the potential agent to be used in the maintainable management of T. urticae combined with N. californicus

    A model of Islamic tourism towards religious motivation and tourist satisfaction in Malaysia

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    Abstract The aim of this chapter is to explore the roles of religious motivation in the relationship between tourists' antecedents and their destination and satisfaction , and to provide some guidelines to aid tourism professionals in developing and implementing the niche strategy of Islamic tourism for the advancement of the tourism industry of a country such as Malaysia. In the Malaysian context, the religious motivation of international Muslim tourists is increasingly active in their minds, which suggests that tourism professionals consider Shariah-compliant tourism to keep long-term customer relationships. Perceived value, destination image, and service quality influence international Muslim tourists to look to this destination for satisfaction . As a moderation role, the more the level of religious motivation varies, the more the effect of moderator yields. In addition, tourism professionals necessarily require understanding relevant Shariah rules, character­ istics of international Muslim tourists , and the context of the Islamic country so that they can design a Shariah-compliant tourism strategy and policy effective for further growth of the tourism industr

    Effect of Rosemary and Sweet Marjoram on three Predacious Mites of the Family Phytoseiidae (Acari: Phytoseiidae)

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    The direct toxicity of two essential oils, Majorana hortensis, Moench and Rosmarinus officinalis L. to adult females of the predacious mites, Amblyseius zaheri Yousef and El-Borolossy, Amblyseius barkeri (Hughes) and Typhlodromus athiasae Porath and Swirski were tested. Rosemary oil was the most toxic to females of A. barkeri and the least to A. zaheri. In contrast,sweet marjoram oil was relatively toxic to T. athiasae and slightly toxic to A. barkeri. Both essential oils,decreased the food consumption rate at the concentration used for A.barkeri and A. zaheri. Females of A. barkeri and A. zaheri suffered a depression in reproduction when treated with 1% of rosemary oil.Both material used seems to be harmless to T. athiasae at 1%
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