1,939 research outputs found
Survey of Italian pediatricians on awareness, experiences and beliefs regarding direct-to-consumer genetic testing in minors
Background: Our study wanted to assess Italian pediatricians’ awareness, experience and beliefs regarding directto- consumer (DTC) genetic tests (GT) in minors, with a focus on those for predisposition to complex disease, lyfestyle, athletic ability and other inborn talents. Methods: A 28-item questionnaire was administered through the SurveyMonkey® web platform to the 9,086 members of the Italian Society of Pediatrics for which a valid email address was available. The survey was opened from April through November 2017. Statistical analyses were performed using the Graphpad software package. Results: 36.2% of the 442 respondents were aware of DTC-GT, but only 23.1% of them felt adequately prepared to meet families’ information needs. The first three sources of knowledge were the Internet (20.98%), magazines/ newspapers (16.78%) and TV/Radio (14.33%), while companies’ direct marketing activity influenced knowledge only in 2.45% of the cases. Only 16.4% of the aware respondents had been already approached for advice. More than 95% of the pediatricians who were aware would not advise DTC-GT for lifestyle, athletic performance or other inborn skills. 69.2% was unfavourable to susceptibility tests for complex diseases. Most of them expressed an interest in learning more and indicated as preferred sources of information public policies issued by professional societies. Conclusion: The low awareness and experience and the vendors’ tiny contribution to knowledge suggest a still limited penetration of DTC-GT companies in Italy. A great interest in learning more was found. Scientific societies are best positioned to support health professionals in this educational goal thanks to their role of trusted sources of information and guidance
Wide band observations of the X-ray burster GS 1826-238
GS 1826-238 is a well-studied X-ray bursting neutron star in a low mass
binary system. Thermal Comptonisation by a hot electron cloud is a widely
accepted mechanism accounting for its high energy emission, while the nature of
most of its soft X-ray output is not completely understood. A further low
energy component is typically needed to model the observed spectra: pure
blackbody and Comptonisation-modified blackbody radiation by a lower
temperature (a few keV) electron plasma were suggested to explain the low
energy data. We studied the steady emission of GS 1826-238 by means of broad
band (X to soft Gamma-rays) measurements obtained by the INTEGRAL observatory
in 2003 and 2006. The newly developed, up-to-date Comptonisation model CompTB
is applied for the first time to study effectively the low-hard state
variability of a low-luminosity neutron star in a low-mass X-ray binary system.
We confirm that the 3-200 keV emission of \GS is characterised by
Comptonisation of soft seed photons by a hot electron plasma. A single spectral
component is sufficient to model the observed spectra. At lower energies, no
direct blackbody emission is observed and there is no need to postulate a low
temperature Compton region. Compared to the 2003 measurements, the plasma
temperature decreased from 20 to 14 keV in 2006, together with the seed photons
temperature. The source intensity was also found to be 30% lower in 2006,
whilst the average recurrence frequency of the X-ray bursts significantly
increased. Possible explanations for this apparent deviation from the typical
limit-cycle behaviour of this burster are discussed.Comment: 6 pages, 2 figures. Accepted for publication in A&
Ab initio Simulation of Optical Limiting: The Case of Metal-Free Phthalocyanine
We present a fully ab initio, non-perturbative description of the optical
limiting properties of a metal-free phthalocyanine, by simulating the effects
of a broadband electric field of increasing intensity. The results confirm
reverse saturable absorption as leading mechanism for optical limiting
phenomena in this system and reveal that a number of dipole-forbidden
excitations are populated by excited-state absorption, at more intense external
fields. The excellent agreement with the experimental data supports our
approach as a powerful tool to predict optical limiting, in view of
applications
Ultrafast charge transfer and vibronic coupling in a laser-excited hybrid inorganic/organic interface
Hybrid interfaces formed by inorganic semiconductors and organic molecules are intriguing materials for opto-electronics. Interfacial charge transfer is primarily responsible for their peculiar electronic structure and optical response. Hence, it is essential to gain insight into this fundamental process also beyond the static picture. Ab initio methods based on real-time time-dependent density-functional theory coupled to the Ehrenfest molecular dynamics scheme are ideally suited for this problem. We investigate a laser-excited hybrid inorganic/organic interface formed by the electron acceptor molecule 2,3,5,6-tetrafluoro-7,7,8,8-tetracyano-quinodimethane (F4TCNQ) physisorbed on a hydrogenated silicon cluster, and we discuss the fundamental mechanisms of charge transfer in the ultrashort time window following the impulsive excitation. The considered interface is p-doped and exhibits charge transfer in the ground state. When it is excited by a resonant laser pulse, the charge transfer across the interface is additionally increased, but contrary to previous observations in all-organic donor/acceptor complexes, it is not further promoted by vibronic coupling. In the considered time window of 100 fs, the molecular vibrations are coupled to the electron dynamics and enhance intramolecular charge transfer. Our results highlight the complexity of the physics involved and demonstrate the ability of the adopted formalism to achieve a comprehensive understanding of ultrafast charge transfer in hybrid materials
INTEGRAL high energy behaviour of 4U 1812-12
The low mass X-ray binary system 4U 1812-12 was monitored with the INTEGRAL
observatory in the period 2003-2004 and with BeppoSAX on April 20, 2000. We
report here on the spectral and temporal analysis of both persistent and burst
emission. The full data set confirms the persistent nature of this burster, and
reveals the presence of emission up to 200 keV. The persistent spectrum is well
described by a comptonization (CompTT) model plus a soft blackbody component.
The source was observed in a hard spectral state with a 1-200 keV luminosity of
2*10^(36) ergs/s and L/LEdd~1% and no meaningful flux variation has been
revealed, as also confirmed by a 2004 RXTE observation. We have also detected 4
bursts showing double peaked profiles and blackbody spectra with temperatures
ranging from 1.9 to 3.1 keV.Comment: 6 pages, 4 figures. Accepted for publication by A&
The failed state transition of the ATOLL source GRS 1724-308
The 2004-2012 X-ray time history of the NS LMXB GRS 1724-308 shows, along
with the episodic brightenings associated to the low-high state transitions
typical of the ATOLL sources, a peculiar, long lasting (about 300 d) flaring
event, observed in 2008. This rare episode, characterised by a high-flux hard
state, has never been observed before for GRS 1724-308 , and in any case is not
common among ATOLL sources. We discuss here different hypotheses on the origin
of this peculiar event that displayed the spectral signatures of a failed
transition, similar in shape and duration to those rarely observed in Black
Hole binaries. We also suggest the possibility that the atypical flare occurred
in coincidence with a new rising phase of the 12-years super-orbital modulation
that has been previously reported by other authors. The analysed data also
confirm for GRS 1724-308 the already reported orbital period of about 90 d.Comment: accepted for publication in MNRA
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