7,244 research outputs found

    Fibers on a graph with local load sharing

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    We study a random fiber bundle model with tips of the fibers placed on a graph having co-ordination number 3. These fibers follow local load sharing with uniformly distributed threshold strengths of the fibers. We have studied the critical behaviour of the model numerically using a finite size scaling method and the mean field critical behaviour is established. The avalanche size distribution is also found to exhibit a mean field nature in the asymptotic limit.Comment: 9 pages, 6 figures, To appear in International Journal of Modern Physics

    Quantum Effects in Neural Networks

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    We develop the statistical mechanics of the Hopfield model in a transverse field to investigate how quantum fluctuations affect the macroscopic behavior of neural networks. When the number of embedded patterns is finite, the Trotter decomposition reduces the problem to that of a random Ising model. It turns out that the effects of quantum fluctuations on macroscopic variables play the same roles as those of thermal fluctuations. For an extensive number of embedded patterns, we apply the replica method to the Trotter-decomposed system. The result is summarized as a ground-state phase diagram drawn in terms of the number of patterns per site, Ξ±\alpha, and the strength of the transverse field, Ξ”\Delta. The phase diagram coincides very accurately with that of the conventional classical Hopfield model if we replace the temperature T in the latter model by Ξ”\Delta. Quantum fluctuations are thus concluded to be quite similar to thermal fluctuations in determination of the macroscopic behavior of the present model.Comment: 34 pages, LaTeX, 9 PS figures, uses jpsj.st

    Nutation versus angular dependent NQR spectroscopy and the impact of underdoping on charge inhomogeneities in YBa2_2Cu3_3Oy_y

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    We describe two different nuclear quadrupole resonance (NQR) based techniques, designed to measure the local asymmetry of the internal electric field gradient, and the tilt angle of the main NQR principal axis z from the crystallographic axis c. These techniques use the dependence of the NQR signal on the duration of the radio frequency (rf) pulse and on the direction of the rf field H1 with respect to the crystal axis. The techniques are applied to oriented powder of YBa2_{2}Cu%_{3}Oy_{y} fully enriched with 63Cu. Measurements were performed at different frequencies, corresponding to different in-plane copper sites with respect to the dopant. Combining the results from both techniques, we conclude that oxygen deficiency in the chain layer lead to a rotation of the NQR main principal axis at the nearby Cu on the CuO2 planes by 20+-degrees. This occurs with no change to the asymmetry. The axis rotation associated with oxygen deficiency means that there must be electric field inhomogeneities in the CuO2 planes only in the vicinity of the missing oxygen.Comment: 9 pages, 10 figure

    Capacity strengthening in malaria research: the Gates Malaria Partnership.

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    The Gates Malaria Partnership (GMP) includes five African and four European partner institutions. Its research programme has five priority areas involving an extensive range of field-based studies. GMP research has contributed significantly to the development of new research consortia investigating strategies for improving means of malaria control, and has already had an impact on policy and practice. A substantial investment in innovative training activities in malaria has enhanced knowledge and practice of malaria control at all levels from policy making to local community involvement. Capacity development, notably through a PhD programme, has been an underlying feature of all aspects of the programme

    Morbidity Pattern Among Out-Patients Attending Urban Health Training Centre in Srinagar

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    The current study was designed to identify the morbidity pattern of out-patients attending Urban Health Training Centre in an urban area of a medical college in Srinagar, Pauri Garhwal district, Uttarakhand, North India. The present study record-based retrospective study was conducted among the out-patients attending the regular clinic at the Urban Health Training Centre, of a medical college in Srinagar city of Uttarakhand State of North India during the study period of one year in 2014. Data was retrieved from the OPD registers maintained at the clinic. Data was collected pertaining to socio-demographic profile, morbidity details and treatment pattern. Diseases were identified using the International Classification of Diseases (ICD-10) code. Descriptive analysis was done. During the study period, a total of 9343 subjects attended the OPD. Among them, majority of them (60%) were females. More than half (56 %) belonged to the age group of 35-65 year age-group. The association of disease classification was found to be statistically significant with respect to gender. The leading morbidity of communicable disease was found to be certain infectious and parasitic diseases especially Typhoid whereas musculoskeletal system and connective tissue disorders were the most common cause among morbidity due to NCDs. Out of all, typhoid was found to cause maximum of morbidity among the subjects. The present study highlights the morbidity pattern of communicable and NCDs among the population of hilly areas of Garhwal, Uttarakhand India. Priority should be preferred for the regular tracking of diseases in terms of preventive and promotive aspects. Morbidity in the out- door clinics reflects the emerging trend of mixed disease spectrum burden comprising communicable and non-communicable diseases

    Modulation of the local density of states within the dd-density wave theory in the underdoped cuprates

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    The low temperature scanning tunneling microscopy spectra in the underdoped regime is analyzed from the perspective of coexisting dd-density wave and d-wave superconducting states. The calculations are carried out in the presence of a low concentration of unitary impurities and within the framework of the fully self-consistent Bogoliubov-de Gennes theory, which allows local modulations of the magnitude of the order parameters in response to the impurities. Our theory captures the essential aspects of the experiments in the underdoped BSCCO at very low temperatures.Comment: 4 pages, 4 eps figures, RevTex4. New added material as well as reference

    Charge-Inhomogeneity doping relations in YBCO detected by Angle Dependent Nuclear Quadrupole Resonance

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    The origin of charge inhomogeneity in YBa_{2}Cu_{3}O_{y} is investigated using a new experimental method designed to determine the nuclear quadrupole resonance (NQR) asymmetry parameter eta for very wide NQR lines at different positions on the line. The method is based on the measurement of the echo intensity as a function of the angle between the radio frequency field H1 and the principal axis of the electric field gradient. Static charge inhomogeneity deduced from eta>0 are found in this compound, but only in conjunction with oxygen deficiency. This limits considerably the possible forms of charge inhomogeneity in bulk YBa_{2}Cu_{3}O_{y}.Comment: To be published in Phys. Rev. B; Revised version with a correction to figure

    Hybrid LSTM and Encoder-Decoder Architecture for Detection of Image Forgeries

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    With advanced image journaling tools, one can easily alter the semantic meaning of an image by exploiting certain manipulation techniques such as copy-clone, object splicing, and removal, which mislead the viewers. In contrast, the identification of these manipulations becomes a very challenging task as manipulated regions are not visually apparent. This paper proposes a high-confidence manipulation localization architecture which utilizes resampling features, Long-Short Term Memory (LSTM) cells, and encoder-decoder network to segment out manipulated regions from non-manipulated ones. Resampling features are used to capture artifacts like JPEG quality loss, upsampling, downsampling, rotation, and shearing. The proposed network exploits larger receptive fields (spatial maps) and frequency domain correlation to analyze the discriminative characteristics between manipulated and non-manipulated regions by incorporating encoder and LSTM network. Finally, decoder network learns the mapping from low-resolution feature maps to pixel-wise predictions for image tamper localization. With predicted mask provided by final layer (softmax) of the proposed architecture, end-to-end training is performed to learn the network parameters through back-propagation using ground-truth masks. Furthermore, a large image splicing dataset is introduced to guide the training process. The proposed method is capable of localizing image manipulations at pixel level with high precision, which is demonstrated through rigorous experimentation on three diverse datasets

    Sine-Gordon Field Theory for the Kosterlitz-Thouless Transitions on Fluctuating Membranes

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    In the preceding paper, we derived Coulomb-gas and sine-Gordon Hamiltonians to describe the Kosterlitz-Thouless transition on a fluctuating surface. These Hamiltonians contain couplings to Gaussian curvature not found in a rigid flat surface. In this paper, we derive renormalization-group recursion relations for the sine-Gordon model using field-theoretic techniques developed to study flat space problems.Comment: REVTEX, 14 pages with 6 postscript figures compressed using uufiles. Accepted for publication in Phys. Rev.
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