3,325 research outputs found

    Особенности морфологии уролитов жителей города Днепропетровска

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    Приведены первые результаты исследований морфологии уролитов жителей города Днепропетровска. Предложена типизация уролитов по особенностям их морфологии.Наведено перші результати досліджень морфології уролітов жителів міста Дніпропетровська. Запропонована типізація уролітов за особливостями їх морфології.The first results of studies of morphology nephrolyth residents of Dnipropetrovsk. A typing nephrolyth on the specifics of their morphology.

    On the distillation and purification of phase-diffused squeezed states

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    Recently it was discovered that non-Gaussian decoherence processes, such as phase-diffusion, can be counteracted by purification and distillation protocols that are solely built on Gaussian operations. Here, we make use of this experimentally highly accessible regime, and provide a detailed experimental and theoretical analysis of several strategies for purification/distillation protocols on phase-diffused squeezed states. Our results provide valuable information for the optimization of such protocols with respect to the choice of the trigger quadrature, the trigger threshold value and the probability of generating a distilled state

    The Performance and Calibration of the CRAFT Fly's Eye Fast Radio Burst Survey

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    Since January 2017, the Commensal Real-time ASKAP Fast Transients survey (CRAFT) has been utilising commissioning antennas of the Australian SKA Pathfinder (ASKAP) to survey for fast radio bursts (FRBs) in fly's eye mode. This is the first extensive astronomical survey using phased array feeds (PAFs), and a total of 20 FRBs have been reported. Here we present a calculation of the sensitivity and total exposure of this survey, using the pulsars B1641-45 (J1644-4559) and B0833-45 (J0835-4510, i.e.\ Vela) as calibrators. The design of the survey allows us to benchmark effects due to PAF beamshape, antenna-dependent system noise, radio-frequency interference, and fluctuations during commissioning on timescales from one hour to a year. Observation time, solid-angle, and search efficiency are calculated as a function of FRB fluence threshold. Using this metric, effective survey exposures and sensitivities are calculated as a function of the source counts distribution. The implied FRB rate is significantly lower than the 3737\,sky1^{-1}\,day1^{-1} calculated using nominal exposures and sensitivities for this same sample by \citet{craft_nature}. At the Euclidean power-law index of 1.5-1.5, the rate is 10.71.8+2.7(sys)±3(stat)10.7_{-1.8}^{+2.7}\,{\rm (sys)} \, \pm \, 3\,{\rm (stat)}\,sky1^{-1}\,day1^{-1} above a threshold of 57±6(sys)57\pm6\,{\rm (sys)}\,Jy\,ms, while for the best-fit index for this sample of 2.1-2.1, it is 16.61.5+1.9(sys)±4.7(stat)16.6_{-1.5}^{+1.9} \,{\rm (sys)}\, \pm 4.7\,{\rm (stat)}\,sky1^{-1}\,day1^{-1} above a threshold of 41.6±1.5(sys)41.6\pm1.5\,{\rm (sys)}\,Jy\,ms. This strongly suggests that these calculations be performed for other FRB-hunting experiments, allowing meaningful comparisons to be made between them.Comment: 21 pages, 15 figures, 2 tables, accepted for publication in PAS

    Phenomenological constraints on Lemaitre-Tolman-Bondi cosmological inhomogeneities from solar system dynamics

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    We, first, analytically work out the long-term, i.e. averaged over one orbital revolution, perturbations on the orbit of a test particle moving in a local Fermi frame induced therein by the cosmological tidal effects of the inhomogeneous Lemaitre-Tolman-Bondi (LTB) model. The LTB solution has recently attracted attention, among other things, as a possible explanation of the observed cosmic acceleration without resorting to dark energy. Then, we phenomenologically constrain both the parameters K_1 = -\ddot R/R and K_2 = -\ddot R^'/R^' of the LTB metric in the Fermi frame by using different kinds of solar system data. The corrections Δϖ˙\Delta\dot\varpi to the standard Newtonian/Einsteinian precessions of the perihelia of the inner planets recently estimated with the EPM ephemerides, compared to our predictions for them, yield K_1 = (4+8) 10^-26 s^-2, K_2 = (3+7) 10^-23 s^-2. The residuals of the Cassini-based Earth-Saturn range, compared with the numerically integrated LTB range signature, allow to obtain K_1/2 = 10^-27 s^-2. The LTB-induced distortions of the orbit of a typical object of the Oort cloud with respect to the commonly accepted Newtonian picture, based on the observations of the comet showers from that remote region of the solar system, point towards K_1/2 <= 10^-30-10^-32 s^-2. Such figures have to be compared with those inferred from cosmological data which are of the order of K1 \approx K2 = -4 10^-36 s^-2.Comment: LaTex2e, 18 pages, 3 tables, 3 figures. Minor changes. Reference added. Accepted by Journal of Cosmology and Astroparticle Physics (JCAP

    Prevalence and Predictors of Household Food Insecurity among Adult/Youth Dyads at the Initiation of the iCook 4-H Two-Year Obesity Prevention Study

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    Objective: Determine food insecurity prevalence and predictors among adult/youth dyads enrolled in a childhood obesity prevention study (iCook 4-H).Methods: The iCook 4-H intervention was designed for youth (9-10 years old) and their adult main meals preparer to cook, eat, and play together. Although not an inclusion criteria, diverse, low income, and/or rural families were the target during recruitment. At baseline, adults completed surveys on food insecurity, socioeconomic and demographic characteristics and youth anthropometrics were collected with body mass index (BMI) calculated. Descriptive statistics were computed and chi-square analysis was conducted to test differences between potential predictors and food insecurity. Binomial logistic regression was used to assess the relationship between food insecurity and its predictors.Results: Thirty-four percent of households (n=71 of 206) were food insecure. Youth were primarily white (69.9%) and normal weight (58.3%). Adults were also primarily white (74.8%), overweight or obese (67.9%), married (68.9%), not participating in government assistance programs (57.8%), and held no college degree (55.3%). Based on the logistic regression model, households with a non-white youth (OR=13.53; 95% CI=3.33, 55.05), an adult without a college degree (OR=5.62; 95% CI=2.01, 15.73), and government assistance program participation (OR=5.63; 95% CI=2.63, 12.07) were significantly associated with household food insecurity. However, there was no significant association with BMI found (youth p=0.167; adult p=0.179).Conclusion: Consistent with previous findings, household food insecurity status was associated with youth race, adult education, and government assistance program participation. In contrast, no relationship between BMI and food insecurity status was observed in this study, which warrants further investigation

    Cold gas outflows from the Small Magellanic Cloud traced with ASKAP

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    Feedback from massive stars plays a critical role in the evolution of the Universe by driving powerful outflows from galaxies that enrich the intergalactic medium and regulate star formation. An important source of outflows may be the most numerous galaxies in the Universe: dwarf galaxies. With small gravitational potential wells, these galaxies easily lose their star-forming material in the presence of intense stellar feedback. Here, we show that the nearby dwarf galaxy, the Small Magellanic Cloud (SMC), has atomic hydrogen outflows extending at least 2 kiloparsecs (kpc) from the star-forming bar of the galaxy. The outflows are cold, T<400 KT<400~{\rm K}, and may have formed during a period of active star formation 256025 - 60 million years (Myr) ago. The total mass of atomic gas in the outflow is 107\sim 10^7 solar masses, M{\rm M_{\odot}}, or 3\sim 3% of the total atomic gas of the galaxy. The inferred mass flux in atomic gas alone, M˙HI0.21.0 M yr1\dot{M}_{HI}\sim 0.2 - 1.0~{\rm M_{\odot}~yr^{-1}}, is up to an order of magnitude greater than the star formation rate. We suggest that most of the observed outflow will be stripped from the SMC through its interaction with its companion, the Large Magellanic Cloud (LMC), and the Milky Way, feeding the Magellanic Stream of hydrogen encircling the Milky Way.Comment: Published in Nature Astronomy, 29 October 2018, http://dx.doi.org/10.1038/s41550-018-0608-

    SCORPIO-II: Spectral indices of weak Galactic radio sources

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    In the next few years the classification of radio sources observed by the large surveys will be a challenging problem, and spectral index is a powerful tool for addressing it. Here we present an algorithm to estimate the spectral index of sources from multiwavelength radio images. We have applied our algorithm to SCORPIO (Umana et al. 2015), a Galactic Plane survey centred around 2.1 GHz carried out with ATCA, and found we can measure reliable spectral indices only for sources stronger than 40 times the rms noise. Above a threshold of 1 mJy, the source density in SCORPIO is 20 percent greater than in a typical extra-galactic field, like ATLAS (Norris et al. 2006), because of the presence of Galactic sources. Among this excess population, 16 sources per square degree have a spectral index of about zero, suggesting optically thin thermal emission such as Hii regions and planetary nebulae, while 12 per square degree present a rising spectrum, suggesting optically thick thermal emission such as stars and UCHii regions.Comment: 12 pages, 11 figures, accepted by MNRA
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