2,173 research outputs found

    Aspects of Noncommutative Scalar/Tensor Duality

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    We study the noncommutative massless Kalb-Ramond gauge field coupled to a dynamical U(1) gauge field in the adjoint representation together with a compensating vector field. We derive the Seiberg-Witten map and obtain the corresponding mapped action to first order in θ\theta. The (emergent) gravity structure found in other situations is not present here. The off-shell dual scalar theory is derived and it does not coincide with the Seiberg-Witten mapped scalar theory. Dispersion relations are also discussed. The p-form generalization of the Seiberg-Witten map to order θ\theta is also derived.Comment: 7 pages, typos corrected, a footnote removed and a sentence added in the tex

    Utility of multiple segment stimulation and serial nerve conduction studies in Guillain Barre Syndrome

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    INTRODUCTION: Guillain-Barre syndrome is a common cause of acute and severe generalised neuropathic weakness. Nerve conduction studies are the most important diagnostic tests. It is classified into various subtypes based on the electrophysiological characteristics. Prolonged distal motor latency and conduction block are features of AIDP. The characteristic electrophysiological features of AMAN are reduced amplitude or absence of distal compound muscle action potentials indicating axonal degeneration. Recently there is growing recognition of reversible conduction blocks in AMAN. OBJECTIVES: To evaluate the utility of multiple segment stimulation of motor nerves, proximal conductions and serial nerve conduction studies in patients with Guillain Barre syndrome. METHODS: Ten patients admitted within the first week of onset of weakness diagnosed with GBS were included in the study and underwent multiple segment stimulation of upper limb motor nerves as well as proximal conductions as part of the electrophysiological study and were followed up with serial nerve conduction study every week till they improved by one Hughes grade or till 4 weeks. The data was analysed using the SPSS software and the chi-square test was used for analysis of significance. RESULTS: H-reflex abnormalities and prolonged / absent F-wave latencies were the most common electrophysiological abnormalities in the nerve conduction study done in the first week of illness. Multiple segment stimulation of motor nerves showed a higher yield of detecting conduction blocks in the first week especially across the entrapment sites. Two patients who had conduction blocks in the multiple segment stimulation in the first study and fulfilling the criteria for AIDP, had completely in-excitable motor nerves in the second conduction done one week later with evidence of active denervation on needle EMG suggestive of an axonal pathology. CONCLUSION: Multiple segment stimulation helps in the detection of a higher percentage of conduction blocks in patient with GBS. Serial nerve conductions are important as there can be change in the electrophysiological classification with time. Some of the motor nerves showing conduction blocks may be on follow up show evidence of axonal degeneration and may indicate an electrophysiological feature of acute motor axonal neuropathy

    The Structure and Content of Zen Stories

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    Zen stories are believed to have been used by priests for centuries to teach disciples. The priests have structured and presented their experiences and their ancestors as stories.  Zen stories record the cultural changes that took place in the society and is about the concepts necessary for people's lives.  These stories explain the structures like family, group, society and the feelings that unite people in the name of God, caste, religion, tolerance, equality, faith etc.  Such Zen stories has folklore elements. Zen stories are thought-provoking, makes us to laugh-out-loud and conveys the traditional ideas. This article discusses other folk motifs found in Zen stories.  Also, in this article, the Zen stories are compiled and sorted into four categories: wisdom and ignorance, action, desire less-ness and impermanence

    Equilibrium in the Food Chain System in the Novels of R. Murugavel

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    Literature is composed based on the theme of the natural environment. Literature expresses the nature of environment either explicitly or implicitly. It remains as a constant canon from the Sangam literature to the contemporary literature. Thus, there are many records in the literature about the natural food chain system and the effects of human production methods on their balance. Literary genre novel also records all these things. After India's independence, the Indian government focused on conserving natural resources and maximizing its productivity.  Its influences are reflected in modern literature. In the drive to maximize productivity, little attention has been paid in protecting the natural environment. Novels carry all such messages both explicitly and implicitly.  Among them, the above-mentioned food chain system, their balance and the impact of human production methods on their balance is revealed in this article

    Agricultural Production Ecosystems in Nanila as revealed in Sangam literature

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    About 2000 years ago, the people of the Sangam Age were familiar with the ecology of the four lands. They adopted various methods of production to meet the demand for food production and to boost the economy. Among them, agriculture, cattle rearing, fishing and salt cultivation were the most important methods of production. This article reveals them. This article also explains their mastery over the methods of production adopted at that time. In particular, the records of Sangam literature describe the stages of development of agriculture, the characteristics of agricultural lands and the methods of cultivation of crops which are the most beneficial of the production methods to meet the food needs of man

    Using the null-stream of GEO600 to veto transient events in the detector output

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    A network of gravitational wave detectors is currently being commissioned around the world. Each of these detectors will search for gravitational waves from various astronomical sources. One of the main searches underway is for un-modelled, transient gravitational wave events. The nature of these signals is such that it will be difficult to distinguish them from bursts of instrumental noise that originate in or around the detector and which then couple to the main detector output. One way to deal with this is to look for events that are coincident in more than one gravitational wave detector. However, with very large event lists (potentially thousands of events per day per detector), the number of events that pass this test due to random chance can still be large. At each detector site, various methods are being developed to veto instrumental bursts from lists of candidate events from that particular detector. This reduces the size of the event lists of each detector, and hopefully the final coincident event list, to a more manageable level. This paper presents one such veto method that can be used to veto certain classes of transient events detected in the output data stream of GEO 600. The method uses events detected in the null-stream output of GEO 600 (which contains, in principle, no gravitational wave signal) with a threshold to veto events detected in the main strain output. We show that, for the certain types of signals tested, the method is very robust, delivering high efficiency for a very low false-veto rate. In particular, it is shown that when applied to real detector data, the method is able to strongly veto a certain type of events which appear around 370 Hz in the detector output

    Auditory processing in individuals with auditory neuropathy

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    BACKGROUND: Auditory neuropathy is a disorder characterized by no or severely impaired auditory brainstem responses in presence of normal otoacoustic emissions and/or cochlear microphonics. Speech perception abilities in these individuals are disproportionate to their hearing sensitivity and reported to be dependent on cortical evoked potentials and temporal processing abilities. The disproportionate loss of auditory percept in presence of normal cochlear function is suggestive of impairment of auditory neural synchrony. METHODS: We studied the auditory evoked potentials and psychophysical abilities in 14 adults with auditory neuropathy to characterize their perceptual capabilities. Psychophysical tests included measurement of open set speech identification scores, just noticeable difference for transition duration of syllable /da/ and temporal modulation transfer function. Auditory evoked potentials measures were, recording of P(1)/N(1), P(2)/N(2 )complex and mismatch negativity (MMN). RESULTS: Results revealed a significant correlation between temporal processing deficits and speech perception abilities. In majority of individuals with auditory neuropathy P(1)/N(1), P(2)/N(2 )complex and mismatch negativity could be elicited with normal amplitude and latency. None of the measured evoked potential parameters correlated with the speech perception scores. Many of the subjects with auditory neuropathy showed normal MMN even though they could not discriminate the stimulus contrast behaviorally. CONCLUSION: Conclusions drawn from the study are 1. Individuals with auditory neuropathy have severely affected temporal processing. 2. The presence of MMN may not be directly linked to presence of behavioral discrimination and to speech perception capabilities at least in adults with auditory neuropathy
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