4,245 research outputs found

    Integrals of monomials over the orthogonal group

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    A recursion formula is derived which allows to evaluate invariant integrals over the orthogonal group O(N), where the integrand is an arbitrary finite monomial in the matrix elements of the group. The value of such an integral is expressible as a finite sum of partial fractions in NN. The recursion formula largely extends presently available integration formulas for the orthogonal group.Comment: 9 pages, no figure

    Testing statistical bounds on entanglement using quantum chaos

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    Previous results indicate that while chaos can lead to substantial entropy production, thereby maximizing dynamical entanglement, this still falls short of maximality. Random Matrix Theory (RMT) modeling of composite quantum systems, investigated recently, entails an universal distribution of the eigenvalues of the reduced density matrices. We demonstrate that these distributions are realized in quantized chaotic systems by using a model of two coupled and kicked tops. We derive an explicit statistical universal bound on entanglement, that is also valid for the case of unequal dimensionality of the Hilbert spaces involved, and show that this describes well the bounds observed using composite quantized chaotic systems such as coupled tops.Comment: 5 pages, 3 figures, to appear in PRL. New title. Revised abstract and some changes in the body of the pape

    Frequency of Clinical Symptoms of Gastroesophageal Reflux Disease in Asthmatic Patients

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    Background: Gastroesophageal reflex is known as an acid reflex, is long term condition where stomach contents back into the oesophagus resulting in either symptoms or complications. GERD disease is caused by weakness or failure of the lower oesophageal sphincter. Symptoms include the acidic taste behind the mouth, heart burn, chest pain, difficult breathing and vomiting. Complication includes esophagitis, oesophageal strictures and barrettes oesophagus. Objective: The aim of this research was to introduce the symptoms of GERD disease in asthmatic patients and how these symptoms worsen the symptoms of asthma disease and what clinical pictures present with the asthmatic disease. Methodology: A designed performa was used to collect the data and after filling the performa, results were drawn and conclusion through the facts and the information given by patients. Results: In the present study among all 164 asthmatic patients, 70 (42.7%) patients showed dyspepsia, 58 (35.4%) were with chest burning, 23 (14%) were asking about chest pain, with acidic mouth taste were 39 (23.8%), 22 (13.4%) were feeling sore throat and 44 (26.8%) showed regurgitation reflex. Among these 164 patients 16 (9.8%) were smokers and 148 (90.2 %) were non-smokers. 47 (28.7%) were males and 117 (71.3%) were females. Conclusion: It is concluded that gastroesophageal reflux disease in asthmatic patients present symptoms of acidic mouth taste, chest burning, chest pain, dyspepsia, regurgitation reflex and sore throat

    A novel Multi-permittivity Cylindrical Dielectric Resonator Antenna for Wideband Applications

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    In this paper, a novel multi-permittivity cylindrical dielectric resonator antenna for wideband application is presented. The multi-permittivity cylinder is formed by combining two different permittivity material sectors in such a way that each sector (with constant permittivity) is 90 degree apart. A direct microstrip line coupling terminated with T-stub at the open end is used to excite the multi-permittivity cylindrical dielectric resonator. The angular position of the multi sector dielectric resonator with respect to the longitudinal axis of the microstrip line and length of the additional strip at the open end of the feeding circuit is key parameters for wideband operation of the antenna. By optimizing all parameters of the proposed antenna, wideband impedance bandwidth of 56% (12.1 GHz - 21.65 GHz) is achieved. The average gain of the antenna throughout the bandwidth is 5.9 dB with good radiation properties in both E-plane and H-plane. A well matched simulation and experimental results show that the antenna is suitable for wideband applications

    Mutations in phosphodiesterase 6 identified in familial cases of retinitis pigmentosa.

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    To delineate the genetic determinants associated with retinitis pigmentosa (RP), a hereditary retinal disorder, we recruited four large families manifesting cardinal symptoms of RP. We localized these families to regions on the human genome harboring the α and β subunits of phosphodiesterase 6 and identified mutations that were absent in control chromosomes. Our data suggest that mutations in PDE6A and PDE6B are responsible for the retinal phenotype in these families

    Beaconless Packet Forwarding Approach for Vehicular Urban Environment

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    Existing wireless technologies provide communication and information services to all fields of life. The one of the emerging and popular field is vehicular ad hoc networks, with its unique characteristics and highly mobile environment. Different types of routing protocols have been proposed to address the routing issues in network and one of the most efficient types is geographical routing. In this type of protocols, the beacon messages are using to update the node locations and positions. However, these protoocls have been suffered with high channel congestion issue in the network. To this end, we propose a beaconless packet forwarding strategy based on modified handshake messages mechanism. The protocol uses some realistic metrics to select the next forwarder node such as forward progresss and link quality. The protocol performance is evaluated with existing beacon and beaconless geographical routing protocols. The simulation results showed the better performance of the proposed protocol in terms of packet delay and data delivery ratio in realistic wireless channel conditions

    The effect of the cation alkyl chain length on density and diffusion in dialkylpyrrolidinium bis(mandelato)borate ionic liquids

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    Diffusion behaviour and non-linear dependence of density of [CnC1Pyrr][BMB] ionic liquids on the number of CH2 groups in the long alkyl chains of the cations were described using an additive model, in which ‘ionic’ and ‘aliphatic’ regions make additive contributions.</p

    Eigenfunctions of electrons in weakly disordered quantum dots: Crossover between orthogonal and unitary symmetries

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    A one-parameter random matrix model is proposed for describing the statistics of the local amplitudes and phases of electron eigenfunctions in a mesoscopic quantum dot in an arbitrary magnetic field. Comparison of the statistics obtained with recent results derived from first principles within the framework of supersymmetry technique allows to identify a transition parameter with real microscopic characteristics of the problem. The random-matrix model is applied to the statistics of the height of the resonance conductance of a quantum dot in the regime of the crossover between orthogonal and unitary symmetry classes.Comment: 6 pages (latex), 3 figures available upon request, to appear in Physical Review

    Self-diffusion of phosphonium Bis(Salicylato)Borate ionic liquid in pores of Vycor porous glass

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    H-1 NMR pulsed field gradient was used to study self-diffusion of a phosphonium bis(salicylato)borate ionic liquid ([P6,6,6,14][BScB]) in the pores of Vycor porous glass at 296 K. Confinement in pores increases diffusion coefficients of the ions by a factor of 35. However, some [P6,6,634][BScB] ions demonstrated apparent diffusion coefficients much lower than their mean values, which may be due to partially restricted diffusion of the ions. We suggest that this fraction corresponds to areas where ions are confined by pore 'necks' (micropores) and empty voids. Heating of the ionic liquid/Vycor system at 330 K led to a change in the diffusivity of the ions, because of their redistribution in the pores. The size of the bounded regions is on the order of 1 mu m, as estimated from the dependence of the ion diffusivity on the diffusion time.</p
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