34,465 research outputs found
and interactions and the LHCb hidden-charmed pentaquarks
Very recently, two hidden-charmed resonances and
consistent with pentaquark states were observed at the LHCb detector. The two
states locate just below the and
thresholds with mass of gaps about 5 and 15 MeV, respectively. Inspired by this
fact we perform a dynamical investigation about the
and interactions which are described by the meson
exchanges. A bound state which carries spin-parity is produced from
the interaction, which is consistent with the
observed at the LHCb detector. From the
interaction, a bound state with is produced, which can be related to
the . The results suggest that the and are
good candidates of and
molecular states, respectively.Comment: 5 pages, 3 figures, published version in Phys. Lett.
Early-onset neonatal sepsis: Still room for improvement in procalcitonin diagnostic accuracy studies
To perform a systematic review assessing accuracy and completeness of diagnostic studies of procalcitonin (PCT) for early-onset neonatal sepsis (EONS) using the Standards for Reporting of Diagnostic Accuracy (STARD) initiative.EONS, diagnosed during the first 3 days of life, remains a common and serious problem. Increased PCT is a potentially useful diagnostic marker of EONS, but reports in the literature are contradictory. There are several possible explanations for the divergent results including the quality of studies reporting the clinical usefulness of PCT in ruling in or ruling out EONS.We systematically reviewed PubMed, Scopus, and the Cochrane Library databases up to October 1, 2014. Studies were eligible for inclusion in our review if they provided measures of PCT accuracy for diagnosing EONS. A data extraction form based on the STARD checklist and adapted for neonates with EONS was used to appraise the quality of the reporting of included studies.We found 18 articles (1998-2014) fulfilling our eligibility criteria which were included in the final analysis. Overall, the results of our analysis showed that the quality of studies reporting diagnostic accuracy of PCT for EONS was suboptimal leaving ample room for improvement. Information on key elements of design, analysis, and interpretation of test accuracy were frequently missing.Authors should be aware of the STARD criteria before starting a study in this field. We welcome stricter adherence to this guideline. Well-reported studies with appropriate designs will provide more reliable information to guide decisions on the use and interpretations of PCT test results in the management of neonates with EONS
Apparent Fractality Emerging from Models of Random Distributions
The fractal properties of models of randomly placed -dimensional spheres
(=1,2,3) are studied using standard techniques for calculating fractal
dimensions in empirical data (the box counting and Minkowski-sausage
techniques). Using analytical and numerical calculations it is shown that in
the regime of low volume fraction occupied by the spheres, apparent fractal
behavior is observed for a range of scales between physically relevant
cut-offs. The width of this range, typically spanning between one and two
orders of magnitude, is in very good agreement with the typical range observed
in experimental measurements of fractals. The dimensions are not universal and
depend on density. These observations are applicable to spatial, temporal and
spectral random structures. Polydispersivity in sphere radii and
impenetrability of the spheres (resulting in short range correlations) are also
introduced and are found to have little effect on the scaling properties. We
thus propose that apparent fractal behavior observed experimentally over a
limited range may often have its origin in underlying randomness.Comment: 19 pages, 12 figures. More info available at
http://www.fh.huji.ac.il/~dani
Results from the ANTARES Neutrino Telescope
A primary goal of a deep-sea neutrino telescopes as ANTARES is the search for
astrophysical neutrinos in the TeV-PeV range. ANTARES is today the largest
neutrino telescope in the Northern hemisphere. After the discovery of a cosmic
neutrino diffuse flux by the IceCube, the understanding of its origin has
become a key mission in high-energy astrophysics. ANTARES makes a valuable
contribution for sources located in the Southern sky thanks to its excellent
angular resolution in both the muon channel and the cascade channel (induced by
all neutrino flavors).
Assuming various spectral indexes for the energy spectrum of neutrino
emitters, the Southern sky and in particular central regions of our Galaxy are
studied searching for point-like objects and for extended regions of emission.
In parallel, by adopting a multimessenger approach, based on time and/or space
coincidences with other cosmic probes, the sensitivity of such searches can be
considerably augmented. ANTARES has participated to a high-energy neutrino
follow-up of the gravitational wave signal GW150914, providing the first
constraint on high-energy neutrino emission from a binary black hole
coalescence. ANTARES has also performed indirect searches for Dark Matter,
yielding limits for the spin-dependent WIMP-nucleon cross-section that improve
upon those of current direct-detection experiments.Comment: Proceedings of the CRIS2016 (10th Cosmic Ray International Seminar) -
Ischia (NA) Italy, July 4-8, 201
The ASTRI mini-array within the future Cherenkov Telescope Array
The Cherenkov Telescope Array (CTA) is a large collaborative effort aimed at
the design and operation of an observatory dedicated to very high-energy
gamma-ray astrophysics in the energy range from a few tens of GeV to above 100
TeV, which will yield about an order of magnitude improvement in sensitivity
with respect to the current major arrays (H.E.S.S., MAGIC, and VERITAS). Within
this framework, the Italian National Institute for Astrophysics is leading the
ASTRI project, whose main goals are the design and installation on Mt. Etna
(Sicily) of an end-to-end dual-mirror prototype of the CTA small size telescope
(SST) and the installation at the CTA Southern site of a dual-mirror SST
mini-array composed of nine units with a relative distance of about 300 m. The
innovative dual-mirror Schwarzschild-Couder optical solution adopted for the
ASTRI Project allows us to substantially reduce the telescope plate-scale and,
therefore, to adopt silicon photo-multipliers as light detectors. The ASTRI
mini-array is a wider international effort. The mini-array, sensitive in the
energy range 1-100 TeV and beyond with an angular resolution of a few arcmin
and an energy resolution of about 10-15%, is well suited to study relatively
bright sources (a few erg cms at 10 TeV) at very
high energy. Prominent sources such as extreme blazars, nearby well-known BL
Lac objects, Galactic pulsar wind nebulae, supernovae remnants, micro-quasars,
and the Galactic Center can be observed in a previously unexplored energy
range. The ASTRI mini-array will extend the current IACTs sensitivity well
above a few tens of TeV and, at the same time, will allow us to compare our
results on a few selected targets with those of current (HAWC) and future
high-altitude extensive air-shower detectors.Comment: Proceedings of the "The Roma International Conference on
Astroparticle Physics (RICAP) 2014". Submitted to EPJ Web of Conferences. 5
pages, 5 figures. ((1) INAF/IASF Palermo, (2)
http://www.brera.inaf.it/astri/, (3) https://portal.cta-observatory.org
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