4,103 research outputs found
EoR Foregrounds: the Faint Extragalactic Radio Sky
A wealth of new data from upgraded and new radio interferometers are rapidly
improving and transforming our understanding of the faint extra-galactic radio
sky. Indeed the mounting statistics at sub-mJy and uJy flux levels is finally
allowing us to get stringent observational constraints on the faint radio
population and on the modeling of its the various components. In this paper I
will provide a brief overview of the latest results in areas that are
potentially important for an accurate treatment of extra-galactic foregrounds
in experiments designed to probe the Epoch of Reionization.Comment: 8 pages, 2 figures. Invited review at IAU Symposium No. 333 "Peering
towards Cosmic Dawn". This submission includes updated figures wrt the
version published in the proceedings volume (where an error in the plotting
routine produced wrong labels for the y- and x-axis
Syncope in Elderly People: A Threatening Presentation of Pulmonary Embolism: A Case Report
age. Its prognosis is largely unpredictable, pending the origin of the sudden loss of
consciousness. We report a case of an old woman affected by severe chronic heart
failure, who died soon after the development of an episode of syncope, which was
eventually attributed to pulmonary embolism. Anticoagulant therapy, promptly
instituted, was ineffective. In the differential diagnoses of syncope, pulmonary
embolism should always be considered, especially in old patients with risk factors
for venous thromboembolism such as a severe heart failure. In patients with high
risk of death according to the widely adopted risk stratifications score, aggressive
therapy may be considered also in elderly people to prevent unfavourable
outcomes
Improving elevation perception with a tool for image-guided head-related transfer function selection
This paper proposes an image-guided HRTF selection procedure that exploits the relation between features of the pinna shape and HRTF notches. Using a 2D image of a subject's pinna, the procedure selects from a database the HRTF set that best fits the anthropometry of that subject. The proposed procedure is designed to be quickly applied and easy to use for a user without previous knowledge on binaural audio technologies. The entire process is evaluated by means of an auditory model for sound localization in the mid-sagittal plane available from previous literature. Using virtual subjects from a HRTF database, a virtual experiment is implemented to assess the vertical localization performance of the database subjects when they are provided with HRTF sets selected by the proposed procedure. Results report a statistically significant improvement in predictions of localization performance for selected HRTFs compared to KEMAR HRTF which is a commercial standard in many binaural audio solutions; moreover, the proposed analysis provides useful indications to refine the perceptually-motivated metrics that guides the selection
The ATESP 5 GHz radio survey. III. 4.8, 8.6 and 19 GHz follow-up observations of radio galaxies
[Abridged] Physical and evolutionary properties of the sub-mJy radio
population are not entirely known. The radio/optical analysis of the ATESP 5
GHz sample has revealed a significant class of compact flat/inverted
radio-spectrum sources associated to early-type galaxies up to redshift 2. Such
sources are most plausibly triggered by an AGN, but their observational
properties are not entirely consistent with those of standard radio galaxy
populations. In the present work we aim at a better understanding of the radio
spectra of such sources and ultimately of the nature of AGNs at sub-mJy flux
levels. We used the ATCA to get multi-frequency (4.8, 8.6 and 19 GHz)
quasi-simultaneous observations for a representative sub-sample of ATESP radio
sources associated with early-type galaxies (26 objects with S>0.6 mJy). This
can give us insight into the accretion/radiative mechanism that is at work,
since different regimes display different spectral signatures in the radio
domain. From the analysis of the radio spectra, we find that our sources are
most probably jet-dominated systems. ADAF models are ruled out by the high
frequency data, while ADAF+jet scenarios are still consistent with
flat/moderately inverted-spectrum sources, but are not required to explain the
data. We compared our sample with high (>20 GHz) frequency selected surveys,
finding spectral properties very similar to the ones of much brighter (S>500
mJy) radio galaxies extracted from the Massardi et al. (2008) sample. Linear
sizes of ATESP 5 GHz sources associated with early type galaxies are also often
consistent with the ones of brighter B2 and 3C radio galaxies, with possibly a
very compact component that could be associated at least in part to (obscured)
radio-quiet quasar-like objects and/or low power BL Lacs.Comment: Accepted for publication in Astronomy & Astrophysic
The ATESP 5 GHz radio survey IV. 19, 38, and 94 GHz observations and radio spectral energy distributions
It is now established that the faint radio population is a mixture of
star-forming galaxies and faint active galactic nuclei (AGNs), with the former
dominating below S(1.4GHz) \sim 100 muJy and the latter at larger flux
densities. The faint radio AGN component can itself be separated into two main
classes, mainly based on the host-galaxy properties: sources associated with
red/early-type galaxies (like radio galaxies) are the dominant class down to
\sim 100 muJy; quasar/Seyfert--like sources contribute an additional 10-20\%.
One of the major open questions regarding faint radio AGNs is the physical
process responsible for their radio emission. This work aims at investigating
this issue, with particular respect to the AGN component associated with
red/early-type galaxies. Such AGNs show, on average, flatter radio spectra than
radio galaxies and are mostly compact (<= 30 kpc in size). Various scenarios
have been proposed to explain their radio emission. For instance they could be
core/core-jet dominated radio galaxies, low-power BL LACs, or
advection-dominated accretion flow (ADAF) systems. We used the Australia
Telescope Compact Array (ATCA) to extend a previous follow-up multi-frequency
campaign to 38 and 94 GHz. (abridged)Comment: 16 pages, 7 figures, 6 tables. Accepted for publication in A&
Sudden and fulminant deaths of healthy children in Italy during the 2010-11 and 2011-12 seasons: results of an online study
The 2009 pandemic in Italy has been viewed as a false alarm, and it has not been properly understood based on historical precedents and more in-depth studies that have been conducted in other countries. Some of these studies have pointed to a phenomenon of sudden and fulminant death among healthy children, which is not the sole prerogative of pandemic influenza, but was, in 2009, a more frequent occurrence than in previous years. The purpose of this study is to gather such cases occurring during the 2010-11 and 2011-12 seasons. Google Search was used in order to find cases of children and teens with no reported preexisting conditions of relevance and who died suddenly and unexpectedly after exhibiting flu-like symptoms during the two seasons. During the 2010-11 season, 29 deaths were found to meet the above conditions, 18 of which were fulminant and 11 sudden. For the 2011-12 season, there were ten such cases: five fulminant and five sudden. Most of these cases occurred during the period of maximum circulation of the flu virus. Fulminant deaths were three times more frequent during the first of these seasons and involved children of a higher average age than the more recent season. It is not possible to come to any definite conclusions, but there is reason to suspect that the driver of this significant increase may be the A(H1N1)pdm09 virus. Regardless of how one wishes to interpret these results, it is advisable that the surveillance systems be strengthened and more recent study techniques be adopted in order to determine the causes of similar deaths in the future
Prevention and treatment of venous thromboembolism with low-molecular-weight heparins: Clinical implications of the recent European guidelines
Venous thromboembolism (VTE) is an important cause of avoidable morbidity and mortality. However, routine prophylaxis for at-risk patients is underused. Recent guidelines issued by an international consensus group, including the International Union of Angiology (IUA), recommend use of low-molecular-weight heparins (LMWHs) for the treatment of acute VTE and prevention of recurrence, and for prophylaxis in surgical and medical patients. This review highlights current inadequacies in the provision of thromboprophylaxis, and considers the clinical implications of the European guidelines on the prevention and treatment of VTE
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