351 research outputs found

    The supervised IBP: neighbourhood preserving infinite latent feature models

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    We propose a probabilistic model to infer supervised latent variables in the Hamming space from observed data. Our model allows simultaneous inference of the number of binary latent variables, and their values. The latent variables preserve neighbourhood structure of the data in a sense that objects in the same semantic concept have similar latent values, and objects in different concepts have dissimilar latent values. We formulate the supervised infinite latent variable problem based on an intuitive principle of pulling objects together if they are of the same type, and pushing them apart if they are not. We then combine this principle with a flexible Indian Buffet Process prior on the latent variables. We show that the inferred supervised latent variables can be directly used to perform a nearest neighbour search for the purpose of retrieval. We introduce a new application of dynamically extending hash codes, and show how to effectively couple the structure of the hash codes with continuously growing structure of the neighbourhood preserving infinite latent feature space

    General Health Status and Its Related Factors in the Nurses Working in the Educational Hospitals of Shiraz University of Medical Sciences, Shiraz, Iran, 2011

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    Background: Nursing is an extremely stressful profession. Nurses are confronted with a variety of personal, communicational and organizational stresses, which affect their health. Objectives: The current study aimed to assess general health level and its related factors in employed nurses in educational hospitals affiliated to Shiraz University of medical sciences. Materials and Methods: This cross-sectional study was performed on 126 nurses and practical nurses who work in educational hospitals affiliated to Shiraz University of medical sciences selected by multi stage sampling method. Data collecting tools included demographic characteristics and General Health Questionaire-28 (GHQ-28). Descriptive statistics are presented and Chi-square test, t-test, and analysis of variance were used to analyze the data. Results: Of 126 subjects 75 (59.5%) cases were suspects of mental disorders. Also 12.7% had physical disorders, 15.9% had anxiety and sleep disorders, 8.7% had social dysfunction and 6.3% had depression. Average score of mental health was 28.4 .In this study mental health was significantly associated with job satisfaction and economic satisfaction (P < 0.05). Conclusions: With regard to significant relation between mental health, job satisfaction, and economic satisfaction, a system for educating and stress reduction counseling should be established to help nurses effectively coping with stress. Also, improving the work environment, increasing staff, increasing salary, and decreasing working hours may reduce the nurses' exposure to stressful risk factors

    Rare Radiative BcDs1(2460)γB_{c}\rightarrow D_{s1}(2460)\gamma Transition in QCD

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    We investigate the radiative BcDs1γB_{c} \to D_{s1} \gamma transition in the framework of QCD sum rules. In particular, we calculate the transition form factors responsible for this decay in both weak annihilation and electromagnetic penguin channels using the quark condensate, mixed and two-gluon condensate diagrams as well as propagation of the soft quark in the electromagnetic field as non-perturbative corrections. These form factors are then used to estimate the branching ratios of the channels under consideration. The total branching ratio of the BcDs1γB_{c} \to D_{s1} \gamma transition is obtained to be in order of 10510^{-5}, and the dominant contribution comes from the weak annihilation channel.Comment: 24 Pages and 3 Figure

    Lost Relatives of the Gumbel Trick

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    The Gumbel trick is a method to sample from a discrete probability distribution, or to estimate its normalizing partition function. The method re- lies on repeatedly applying a random perturbation to the distribution in a particular way, each time solving for the most likely configuration. We derive an entire family of related methods, of which the Gumbel trick is one member, and show that the new methods have superior properties in several settings with minimal additional computational cost. In particular, for the Gumbel trick to yield computational benefits for discrete graphical models, Gumbel perturbations on all configurations are typically replaced with so- called low-rank perturbations. We show how a subfamily of our new methods adapts to this set- ting, proving new upper and lower bounds on the log partition function and deriving a family of sequential samplers for the Gibbs distribution. Finally, we balance the discussion by showing how the simpler analytical form of the Gumbel trick enables additional theoretical results.Alan Turing Institute under EPSRC grant EP/N510129/1, and by the Leverhulme Trust via the CFI

    Catecholaminergic Innervation of Central and Peripheral Auditory Circuitry Varies with Reproductive State in Female Midshipman Fish, Porichthys notatus

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    In seasonal breeding vertebrates, hormone regulation of catecholamines, which include dopamine and noradrenaline, may function, in part, to modulate behavioral responses to conspecific vocalizations. However, natural seasonal changes in catecholamine innervation of auditory nuclei is largely unexplored, especially in the peripheral auditory system, where encoding of social acoustic stimuli is initiated. The plainfin midshipman fish, Porichthys notatus, has proven to be an excellent model to explore mechanisms underlying seasonal peripheral auditory plasticity related to reproductive social behavior. Recently, we demonstrated robust catecholaminergic (CA) innervation throughout the auditory system in midshipman. Most notably, dopaminergic neurons in the diencephalon have widespread projections to auditory circuitry including direct innervation of the saccule, the main endorgan of hearing, and the cholinergic octavolateralis efferent nucleus (OE) which also projects to the inner ear. Here, we tested the hypothesis that gravid, reproductive summer females show differential CA innervation of the auditory system compared to non-reproductive winter females. We utilized quantitative immunofluorescence to measure tyrosine hydroxylase immunoreactive (TH-ir) fiber density throughout central auditory nuclei and the sensory epithelium of the saccule. Reproductive females exhibited greater density of TH-ir innervation in two forebrain areas including the auditory thalamus and greater density of TH-ir on somata and dendrites of the OE. In contrast, non-reproductive females had greater numbers of TH-ir terminals in the saccule and greater TH-ir fiber density in a region of the auditory hindbrain as well as greater numbers of TH-ir neurons in the preoptic area. These data provide evidence that catecholamines may function, in part, to seasonally modulate the sensitivity of the inner ear and, in turn, the appropriate behavioral response to reproductive acoustic signals

    Linear and Second-order Optical Response of the III-V Mono-layer Superlattices

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    We report the first fully self-consistent calculations of the nonlinear optical properties of superlattices. The materials investigated are mono-layer superlattices with GaP grown on the the top of InP, AlP and GaAs (110) substrates. We use the full-potential linearized augmented plane wave method within the generalized gradient approximation to obtain the frequency dependent dielectric tensor and the second-harmonic-generation susceptibility. The effect of lattice relaxations on the linear optical properties are studied. Our calculations show that the major anisotropy in the optical properties is the result of strain in GaP. This anisotropy is maximum for the superlattice with maximum lattice mismatch between the constituent materials. In order to differentiate the superlattice features from the bulk-like transitions an improvement over the existing effective medium model is proposed. The superlattice features are found to be more pronounced for the second-order than the linear optical response indicating the need for full supercell calculations in determining the correct second-order response.Comment: 9 pages, 4 figures, submitted to Phy. Rev.

    Occupational categories and cardiovascular diseases incidences: A cohort study in Iranian population

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    Introduction: In spite of traditional cardiovascular risk factor, the different occupations can play an important role in cardiovascular disease (CVDs) incidence. We aimed to assess the correlation between the occupational classes, based on the International Standard Classification of Occupation (ISCO), and CVDs in Iran as a developing country. Methods: We followed the 2440 men, aged 35-65 years and without history of CVDs over fourteen years; 2001 to 2015 during the Isfahan Cohort Study. ISCO was used to classify occupations into 10 categories. Incidence rates of ischemic heart diseases and stroke were recorded. Socioeconomic demographic data including marital state, income and place of living and metabolic risk factors were also recorded. Results: The mean age was 46.97±8.31 years old. 272 cardiovascular events (CVEs) were recorded that unstable angina was the highest recorded with 49 prevalence and the fatal stroke had the lowest outbreak (1). The unemployed/jobless group and elementary occupations (9th ISCO category) had higher and lower relative frequency in CVEs respectively. There was non-significant decrease in CVEs in all of categories except of 4th (clerical support workers) and 10th (armed forces) groups in comparison to unemployed/jobless subjects (P> 0.05). After considering of the group 7 as a reference group (most absolute CVEs frequency), in fully adjustment analysis group 4 had significant risk for CVEs (P=0.04). Conclusions: This study indicates that working as clerical support workers (4th ISCO category) is associated with higher significant risk for IHD and stroke incidence in comparison to craft and related trades workers (7th group of ISCO). Copyright © 2020 by Pacini Editore Srl, Pisa, Italy
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