94,450 research outputs found

    Photodynamic Therapy of Necrobiosis Lipoidica - A Multicenter Study of 18 Patients

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    Background: Necrobiosis lipoidica (NL) is a granulomatous skin disease of unknown origin, and no reliably effective treatment option exists to handle this often disfiguring disease. Recently, a patient with long-lasting NL was reported to be cured by topical photodynamic therapy (PDT). Objective: To evaluate the overall potential of PDT in the treatment of NL on the lower legs. Methods: Retrospective study of 18 patients (aged 16 - 62 years) from 3 European university departments of dermatology treated with PDT for NL. Methyl aminolevulinate or 5-aminolevulinic acid were used as topically applied photosensitizers. Illumination followed with red light-emitting diode light. Results: Complete response was seen in 1/18 patients after 9 PDT cycles, and partial response in 6/18 patients (2 - 14 PDT cycles) giving an overall response rate of 39% (7/18). Conclusion: Although almost 40% of the cases showed some degree of response, PDT cannot currently be recommended as first-line therapy of NL. Subpopulations of therapy-resistant NL patients may, however, benefit from PDT. Copyright (C) 2008 S. Karger AG, Base

    Reduced density matrix hybrid approach: Application to electronic energy transfer

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    Electronic energy transfer in the condensed phase, such as that occurring in photosynthetic complexes, frequently occurs in regimes where the energy scales of the system and environment are similar. This situation provides a challenge to theoretical investigation since most approaches are accurate only when a certain energetic parameter is small compared to others in the problem. Here we show that in these difficult regimes, the Ehrenfest approach provides a good starting point for a dynamical description of the energy transfer process due to its ability to accurately treat coupling to slow environmental modes. To further improve on the accuracy of the Ehrenfest approach, we use our reduced density matrix hybrid framework to treat the faster environmental modes quantum mechanically, at the level of a perturbative master equation. This combined approach is shown to provide an efficient and quantitative description of electronic energy transfer in a model dimer and the Fenna-Matthews-Olson complex and is used to investigate the effect of environmental preparation on the resulting dynamics.Comment: 11 pages, 8 figure

    Towards optimized suppression of dephasing in systems subject to pulse timing constraints

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    We investigate the effectiveness of different dynamical decoupling protocols for storage of a single qubit in the presence of a purely dephasing bosonic bath, with emphasis on comparing quantum coherence preservation under uniform vs. non-uniform delay times between pulses. In the limit of instantaneous bit-flip pulses, this is accomplished by establishing a new representation of the controlled qubit evolution, where the resulting decoherence behaviour is directly expressed in terms of the free evolution. Simple analytical expressions are given to approximate the long- and short- term coherence behaviour for both ohmic and supra-ohmic environments. We focus on systems with physical constraints on achievable time delays, with emphasis on pure dephasing of excitonic qubits in quantum dots. Our analysis shows that little advantage of high-level decoupling schemes based on concatenated or optimal design is to be expected if operational constraints prevent pulses to be applied sufficiently fast. In such constrained scenarios, we demonstrate how simple modifications of repeated periodic echo protocols can offer significantly improved coherence preservation in realistic parameter regimes.Comment: 13 figures,1 tabl

    A 4.8 kbps code-excited linear predictive coder

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    A secure voice system STU-3 capable of providing end-to-end secure voice communications (1984) was developed. The terminal for the new system will be built around the standard LPC-10 voice processor algorithm. The performance of the present STU-3 processor is considered to be good, its response to nonspeech sounds such as whistles, coughs and impulse-like noises may not be completely acceptable. Speech in noisy environments also causes problems with the LPC-10 voice algorithm. In addition, there is always a demand for something better. It is hoped that LPC-10's 2.4 kbps voice performance will be complemented with a very high quality speech coder operating at a higher data rate. This new coder is one of a number of candidate algorithms being considered for an upgraded version of the STU-3 in late 1989. The problems of designing a code-excited linear predictive (CELP) coder to provide very high quality speech at a 4.8 kbps data rate that can be implemented on today's hardware are considered

    Spectral Consequences of Deviation from Spherical Composition Symmetry in Type Ia Supernovae

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    We investigate the prospects for constraining the maximum scale of clumping in composition that is consistent with observed Type Ia supernova flux spectra. Synthetic spectra generated without purely spherical composition symmetry indicate that gross asymmetries make prominent changes to absorption features. Motivated by this, we consider the case of a single unblended line forming in an atmosphere with perturbations of different scales and spatial distributions. Perturbations of about 1% of the area of the photodisk simply weaken the absorption feature by the same amount independent of the line of sight. Conversely, perturbations of about 10% of the area of the photodisk introduce variation in the absorption depth which does depend on the line of sight. Thus, 1% photodisk area perturbations may be consistent with observed profile homogeneity but 10% photodisk area perturbations can not. Based on this, we suggest that the absence of significant variation in the depths of Si II 6355 absorption features in normal Type Ia spectra near maximum light indicates that any composition perturbations in these events are quite small. This also constrains future three-dimensional explosion models to produce ejecta profiles with only small scale inhomogeneities.Comment: 11 pages, 6 figure

    Magnetic Fluctuations, Precursor Phenomena and Phase Transition in MnSi under Magnetic Field

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    The reference chiral helimagnet MnSi is the first system where skyrmion lattice correlations have been reported. At zero magnetic field the transition at TCT_C to the helimagnetic state is of first order. Above TCT_C, in a region dominated by precursor phenomena, neutron scattering shows the build up of strong chiral fluctuating correlations over the surface of a sphere with radius 2Ï€/â„“2\pi/\ell, where â„“\ell is the pitch of the helix. It has been suggested that these fluctuating correlations drive the helical transition to first order following a scenario proposed by Brazovskii for liquid crystals. We present a comprehensive neutron scattering study under magnetic fields, which provides evidence that this is not the case. The sharp first order transition persists for magnetic fields up to 0.4 T whereas the fluctuating correlations weaken and start to concentrate along the field direction already above 0.2 T. Our results thus disconnect the first order nature of the transition from the precursor fluctuating correlations. They also show no indication for a tricritical point, where the first order transition crosses over to second order with increasing magnetic field. In this light, the nature of the first order helical transition and the precursor phenomena above TCT_C, both of general relevance to chiral magnetism, remain an open question

    EXPLORATION OFTHE POLITICAL PARTICIPATION OF YOUTH: A SOCIAL MEDIA INTERVENTION WITH REFERENCE TO DIGITAL INDIA AND SWATCH BHARATH MISSIONS

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    Young people between the ages of 15 and 25 constitute a fifth of the world’s population. India is one of the youngest countries in the world, with an estimated 65 percent of the population under the age of 35. UN report says, with 356 million 10-24 year-olds, India has the world’s largest youth population despite having a smaller population than China. There are 243 Million internet users in India and it is likely to increase to 500 Million by 2018 making India larger than the US in terms of the number of Internet users (RajanAnandan, MD, Google India). In 2018, it is estimated that there will be around 283 million social network users in India, up from close to 216.5 million in 2016 (The Statistics Portal). Indians are very active on different social networks and 88% of users share content on their social profiles and as wellincreasingly spend time on various social networking sites. The ease of using and creating social media have spawned an explosion of grassroots participation, allowing individuals to express their opinions more openly and freely as well as to build a more active and significant relationship with official institutions (Rojas H 2012). The Swachh Bharat Abhiyan and Digital India, one is the most significant cleanliness campaign by the Government of India and the other, to ensure that Government services are made available to citizens electronically by improving online infrastructure and increasing Internet connectivity.The purpose of this thematic paper is priority to investigate the relationship between social media use and political participation focusing on India’s two massive movements Swach Bharath and Digital India which happen in the network society. This paper provides an overview of what is considered the power of social media and how it shapes national news agenda with democratic values. It also analyses how social media users shape the future of news and information about these movements. This paper attempts to explain the exposure to human interest and conflict frames of news based on Swach Bharath and Digital India as a result of use of social media and it concludes on all aspects of governance and attempts to improve the quality of life of citizens

    Real-time diagnostics of gas/water assisted injection moulding using integrated ultrasonic sensors

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    YesAn ultrasound sensor system has been applied to the mould of both the water and gas assisted injection moulding processes. The mould has a cavity wall mounted pressure sensor and instrumentation to monitor the injection moulding machine. Two ultrasound sensors are used to monitor the arrival of the fluid (gas or water) bubble tip through the detection of reflected ultrasound energy from the fluid polymer boundary and the fluid bubble tip velocity through the polymer melt is estimated. The polymer contact with the cavity wall is observed through the reflected ultrasound energy from that boundary. A theoretically based estimation of the residual wall thickness is made using the ultrasound reflection from the fluid (gas or water) polymer boundary whilst the samples are still inside the mould and a good correlation with a physical measurement is observed

    Bias Analysis in Entropy Estimation

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    We consider the problem of finite sample corrections for entropy estimation. New estimates of the Shannon entropy are proposed and their systematic error (the bias) is computed analytically. We find that our results cover correction formulas of current entropy estimates recently discussed in literature. The trade-off between bias reduction and the increase of the corresponding statistical error is analyzed.Comment: 5 pages, 3 figure

    Shear viscosity of a superfluid Fermi gas in the unitarity limit

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    We compute the shear viscosity of a superfluid atomic Fermi gas in the unitarity limit. The unitarity limit is characterized by a divergent scattering length between the atoms, and it has been argued that this will result in a very small viscosity. We show that in the low temperature T limit the shear viscosity scales as xi^5/T^5, where the universal parameter 'xi' relates the chemical potential and the Fermi energy, mu=xi E_F. Combined with the high temperature expansions of the viscosity our results suggest that the viscosity has a minimum near the critical temperature T_c. A naive extrapolation indicates that the minimum value of the ratio of viscosity over entropy density is within a factor of ~ 5 of the proposed lower bound hbar/(4\pi k_B).Comment: 9 pages, 7 figures, LaTeX2
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