591 research outputs found
Simulations of cm-wavelength Sunyaev-Zel'dovich galaxy cluster and point source blind sky surveys and predictions for the RT32/OCRA-f and the Hevelius 100-m radio telescope
We investigate the effectiveness of blind surveys for radio sources and
galaxy cluster thermal Sunyaev-Zel'dovich effects (TSZEs) using the four-pair,
beam-switched OCRA-f radiometer on the 32-m radio telescope in Poland. The
predictions are based on mock maps that include the cosmic microwave
background, TSZEs from hydrodynamical simulations, and unresolved radio
sources. We estimate the effects of source clustering towards galaxy clusters
from NVSS source counts around Planck-selected cluster candidates, and include
appropriate correlations in our mock maps. The study allows us to quantify the
effects of halo line-of-sight alignments, source confusion, and telescope
angular resolution on the detections of TSZEs.
We perform a similar analysis for the planned 100-m Hevelius radio telescope
(RTH) equipped with a 49-beam radio camera.
We find that RT32/OCRA-f will be suitable for small-field blind radio source
surveys, and will detect new radio sources brighter than 0.87
mJy at 30~GHz in a 1 deg field at CL during a one-year,
non-continuous, observing campaign, taking account of Polish weather
conditions. It is unlikely that any galaxy cluster will be detected at
CL in such a survey. A -deg survey, with field coverage of
beams per pixel, at 15 GHz with the RTH, would find <1.5 galaxy clusters
per year brighter than 60 Jy (at CL), and would detect about
point sources brighter than 1 mJy at CL, with
confusion causing flux density errors (20%) in 68% (95%) of the
detected sources.
A primary goal of the planned RTH will be a wide-area (~sr) radio source
survey at 15 GHz. This survey will detect nearly radio sources
at CL down to 1.3 mJy, and tens of galaxy clusters, in one year of
operation with typical weather conditions. ABRIDGEDComment: 37 pages, 17 figures, accepted for publication in JCA
Expenditure and resource utilisation for cervical screening in Australia
BACKGROUND The National Cervical Screening Program in Australia currently recommends that women aged 18-69 years are screened with conventional cytology every 2 years. Publicly funded HPV vaccination was introduced in 2007, and partly as a consequence, a renewal of the screening program that includes a review of screening recommendations has recently been announced. This study aimed to provide a baseline for such a review by quantifying screening program resource utilisation and costs in 2010. METHODS A detailed model of current cervical screening practice in Australia was constructed and we used data from the Victorian Cervical Cytology Registry to model age-specific compliance with screening and follow-up. We applied model-derived rate estimates to the 2010 Australian female population to calculate costs and numbers of colposcopies, biopsies, treatments for precancer and cervical cancers in that year, assuming that the numbers of these procedures were not yet substantially impacted by vaccination. RESULTS The total cost of the screening program in 2010 (excluding administrative program overheads) was estimated to be A96.7M were conducted, a further 188,900 smears costing 21.2M were conducted, and about 18,900 treatments for precancerous lesions were performed (including retreatments), associated with a cost of 20.5M was spent on work-up and treatment for approximately 761 women diagnosed with invasive cervical cancer. Overall, an estimated $23 was spent in 2010 for each adult woman in Australia on cervical screening program-related activities. CONCLUSIONS Approximately half of the total cost of the screening program is spent on delivery of primary screening tests; but the introduction of HPV vaccination, new technologies, increasing the interval and changing the age range of screening is expected to have a substantial impact on this expenditure, as well as having some impact on follow-up and management costs. These estimates provide a benchmark for future assessment of the impact of changes to screening program recommendations to the costs of cervical screening in Australia
Cloud Atlas: Weak Color Modulations Due to Rotation in the Planetary-mass Companion GU Psc b and 11 Other Brown Dwarfs
Among the greatest challenges in understanding ultracool brown dwarf and exoplanet atmospheres is the evolution of cloud structure as a function of temperature and gravity. In this study, we present the rotational modulations of GU Psc b—a rare mid-T spectral type planetary-mass companion at the end of the L/T spectral type transition. Based on the Hubble Space Telescope/WFC3 1.1–1.67 μm time-series spectra, we observe a quasi-sinusoidal light curve with a peak-to-trough flux variation of 2.7% and a minimum period of 8 h. The rotation-modulated spectral variations are weakly wavelength-dependent, or largely gray between 1.1 and 1.67 μm. The gray modulations indicate that heterogeneous clouds are present in the photosphere of this low-gravity mid-T dwarf. We place the color and brightness variations of GU Psc b in the context of rotational modulations reported for mid-L to late-T dwarfs. Based on these observations, we report a tentative trend: mid-to-late T dwarfs become slightly redder in J − H color with increasing J-band brightness, while L dwarfs become slightly bluer with increasing brightness. If this trend is verified with more T-dwarf samples, it suggests that in addition to the mostly gray modulations, there is a second-order spectral-type dependence on the nature of rotational modulations
Cloud Atlas: Rotational Spectral Modulations and potential Sulfide Clouds in the Planetary-mass, Late T-type Companion Ross 458C
Measurements of photometric variability at different wavelengths provide
insights into the vertical cloud structure of brown dwarfs and planetary-mass
objects. In seven Hubble Space Telescope consecutive orbits, spanning 10
h of observing time}, we obtained time-resolved spectroscopy of the
planetary-mass T8-dwarf Ross 458C using the near-infrared Wide Field Camera 3.
We found spectrophotometric variability with a peak-to-peak signal of
2.620.02 % (in the 1.10-1.60~m white light curve). Using three
different methods, we estimated a rotational period of 6.751.58~h for the
white light curve, and similar periods for narrow - and - band light
curves. Sine wave fits to the narrow - and -band light curves suggest a
tentative phase shift between the light curves with wavelength when we allow
different periods between both light curves. If confirmed, this phase shift may
be similar to the phase shift detected earlier for the T6.5 spectral type 2MASS
J22282889-310262. We find that, in contrast with 2M2228, the variability of
Ross~458C shows evidence for a {color trend} within the narrow -band, but
gray variations in the narrow -band. The spectral time-resolved variability
of Ross 458C might be potentially due to heterogeneous sulfide clouds in the
atmosphere of the object. Our discovery extends the study of spectral
modulations of condensate clouds to the coolest T dwarfs, planetary-mass
companions.Comment: Accepted in ApJ
Cloud Atlas: High-Contrast Time-Resolved Observations of Planetary-Mass Companions
Directly-imaged planetary-mass companions offer unique opportunities in
atmospheric studies of exoplanets. They share characteristics of both brown
dwarfs and transiting exoplanets, therefore, are critical for connecting
atmospheric characterizations for these objects. Rotational phase mapping is a
powerful technique to constrain the condensate cloud properties in ultra-cool
atmospheres. Applying this technique to directly-imaged planetary-mass
companions will be extremely valuable for constraining cloud models in low mass
and surface gravity atmospheres and for determining the rotation rate and
angular momentum of substellar companions. Here, we present Hubble Space
Telescope Wide Field Camera 3 near-infrared time-resolved photometry for three
planetary-mass companions, AB Pic B, 2M0122B, and 2M1207b. Using two-roll
differential imaging and hybrid point spread function modeling, we achieve
sub-percent photometric precision for all three observations. We find tentative
modulations () for AB Pic B and 2M0122B but cannot reach
conclusive results on 2M1207b due to strong systematics. The relatively low
significance of the modulation measurements cannot rule out the hypothesis that
these planetary-mass companions have the same vertical cloud structures as
brown dwarfs. Our rotation rate measurements, combined with archival period
measurements of planetary-mass companions and brown dwarfs do not support a
universal mass-rotation relation. The high precision of our observations and
the high occurrence rates of variable low-surface gravity objects encourage
high-contrast time-resolved observations with the James Webb Space Telescope.Comment: Accepted for publication in AAS Journa
New trends and ideas in visual concept detection
The MIR Flickr collection consists of 25000 high-quality photographic images of thousands of Flickr users, made available under the Creative Commons license. The database includes all the original user tags and EXIF metadata. Additionally, detailed and accurate annotations are provided for topics corresponding to the most prominent visual concepts in the user tag data. The rich metadata allow for a wide variety of image retrieval benchmarking scenarios. In this paper, we provide an overview of the various strategies that were devised for automatic visual concept detection using the MIR Flickr collection. In particular we discuss results from various experiments in combining social data and low-level content-based descriptors to improve the accuracy of visual concept classifiers. Additionally, we present retrieval result
Cloud Atlas: Discovery of Rotational Spectral Modulations in a Low-mass, L-type Brown Dwarf Companion to a Star
Observations of rotational modulations of brown dwarfs and giant exoplanets
allow the characterization of condensate cloud properties. As of now rotational
spectral modulations have only been seen in three L-type brown dwarfs. We
report here the discovery of rotational spectral modulations in LP261-75B, an
L6-type intermediate surface gravity companion to an M4.5 star. As a part of
the Cloud Atlas Treasury program we acquired time-resolved Wide Field Camera 3
grism spectroscopy (1.1--1.69~m) of LP261-75B. We find gray spectral
variations with the relative amplitude displaying only a weak wavelength
dependence and no evidence for lower-amplitude modulations in the 1.4~m
water band than in the adjacent continuum. The likely rotational modulation
period is 4.780.95 h, although the rotational phase is not well sampled.
The minimum relative amplitude in the white light curve measured over the whole
wavelength range is 2.410.14\%. We report an unusual light curve with
seemingly three peaks approximately evenly distributed in rotational phase. The
spectral modulations suggests that the upper atmosphere cloud properties in
{LP261-75B} are similar to two other mid-L dwarfs of typical infrared colors,
but differ from that of the extremely red L-dwarf WISE0047
Pure-Silica-Zeolite MFI and MEL Low-Dielectric-Constant Films with Fluoro-Organic Functionalization
The synthesis of organic-functionalized pure-silica-zeolites (PSZs) with MFI- and MEL-type structures for low-k applications prepared through a direct-synthesis method by adding a fluorinated silane to the synthesis solution is reported. The added fluorine functionality increases the hydrophobicity of the zeolites, which are characterized by scanning electron microscopy, X-ray diffraction, 29Si and 19F solid-state NMR spectroscopy, nitrogen adsorption, and thermogravimetric analysis. The functionalized zeolite powders have low water content and calcined spin-on films prepared from the functionalized nanoparticle suspensions exhibit higher water contact angles and lower k values (2.1 and 1.8 for the functionalized MFI- and MEL-type zeolites, respectively) than PSZ films. The use of a direct-synthesis method to decrease the moisture adsorption in the films eliminates the extra post-spin-on silylation steps that are traditionally used to render the zeolite films hydrophobic
Efficacy of percutaneous versus intradermal BCG in the prevention of tuberculosis in South African infants: randomised trial
Objective To compare the incidence of tuberculosis over two years in infants vaccinated at birth with intradermal BCG or with percutaneous BCG
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