6,109 research outputs found

    Photonic circuits for generating modal, spectral, and polarization entanglement

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    We consider the design of photonic circuits that make use of Ti:LiNbO3_{3} diffused channel waveguides for generating photons with various combinations of modal, spectral, and polarization entanglement. Down-converted photon pairs are generated via spontaneous optical parametric down-conversion (SPDC) in a two-mode waveguide. We study a class of photonic circuits comprising: 1) a nonlinear periodically poled two-mode waveguide structure, 2) a set of single-mode and two-mode waveguide-based couplers arranged in such a way that they suitably separate the three photons comprising the SPDC process, and, for some applications, 3) a holographic Bragg grating that acts as a dichroic reflector. The first circuit produces frequency-degenerate down-converted photons, each with even spatial parity, in two separate single-mode waveguides. Changing the parameters of the elements allows this same circuit to produce two nondegenerate down-converted photons that are entangled in frequency or simultaneously entangled in frequency and polarization. The second photonic circuit is designed to produce modal entanglement by distinguishing the photons on the basis of their frequencies. A modified version of this circuit can be used to generate photons that are doubly entangled in mode number and polarization. The third photonic circuit is designed to manage dispersion by converting modal, spectral, and polarization entanglement into path entanglement

    Women's Knowledge, Attitudes and Behavior about Maternal Risk Factors in Pregnancy

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    BACKGROUND: The aims of this study were to assess the levels of knowledge, attitudes and behaviors of women about the main maternal risk factors in pregnancy and to identify the factors linked to the main outcomes of interest. MATERIALS AND METHODS: A cross-sectional survey was conducted in 513 pregnant women randomly selected from the gynecological ambulatory services of five hospitals located in Naples, Italy. RESULTS: Only 42% of women correctly knew all the main maternal risk factors in pregnancy (alcohol, smoking, passive smoking and obesity). Only 21.7% of women were very worried about causing harm to the fetus or child with their risk behaviors, and 22.3% of women reported smoking during pregnancy. Approximately one-third of women (28.9%) reported regularly drinking alcohol before pregnancy and 74.8% of these women reported stopping drinking alcohol during pregnancy. However, only 27.3% of women who were drinking alcohol during pregnancy had the intention of stopping. Only 43.7% of women indicated that during ambulatory gynecological examinations they received information from physicians about the possible damage resulting from all the main risk factors in pregnancy (alcohol, smoking, passive smoking and obesity). CONCLUSION: The results indicate that pregnant women lack knowledge regarding the main maternal risk factors. Pregnant women claim to receive little information during gynecological examinations and, therefore, some continue to smoke and drink alcohol during pregnancy. Our results suggest an urgent need for the design of interventions to improve women's levels of knowledge and to promote appropriate behavior in relation to the major risk factors in pregnancy

    Extracting Touristic Information from Online Image Collections

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    In this paper, we present a Geographical Information Retrieval system, which aims to automatically extract and analyze touristic information from photos of online image collections (in our case of study Flickr). Our system collect all the photos, and the related information, that are associated to a specific city. We then use Google Maps service to geolocate the retrieved photos, and finally we analyze geo-referenced data to obtain our goals: 1) determining and locating the most interesting places of the city, i.e. the most visited locations, and 2) reconstructing touristic routes of the users visiting the city. Information is filtered by using a set of constraints, which we apply to select only the users that reasonably are tourists visiting the city. Tests were performed on an Italian city, Palermo, that is rich in artistic and touristic attractions, but preliminary tests showed that our technique could successfully be applied to any city in the world with a reasonable number of touristic landmarks

    Knowledge, Attitudes, and Practices of Avian Influenza, Poultry Workers, Italy

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    We asked Italian poultry workers about knowledge, attitudes, and practices regarding avian influenza. It was perceived to be a low occupational hazard, and wearing protective equipment and handwashing were not routine practices. Knowledge of transmission and preventive measures should be improved. Employers and health professionals should provide more effective information
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