4,128 research outputs found
The compositional and mineralogical analysis of fired pigments in Nasca pottery from Cahuachi (Peru) by the combined use of the portable PIXE-alpha and portable XRD techniques
Abstract An analytical protocol based on the combined use of the portable PIXE-alpha (Particle Induced X-ray Emission) and XRD (X-ray Diffraction) non destructive techniques developed at the LANDIS laboratory (Laboratorio di Analisi Non Distruttive) of the INFN–CNR (Istituto Nazionale di Fisica Nucleare–Consiglio Nazionale delle Ricerche) in Catania (Italy), was applied for the characterisation of the surface paints of some archaeological fragments of Nasca pottery from the Ceremonial Centre of Cahuachi in Southern Peru. Measurements were carried out on the black, white, red, orange and grey pigments; quantitative information on the chemical composition as well as on the mineralogical phases present on the paints were obtained. Results allowed to make some considerations about the materials and the manufacturing technique used to realise such fired pigments. It should be noted that during firing the precursor minerals composing the pigments undergo a phase transformation and their identification presents some difficulties
Introducing The Radiation-Hardened Voltage Regulators Rhfl4913 and the Rhfl6000
With the progressive scaling of the modern CMOS processes arising during the recent years, for the devices operating in space the susceptivity to the over-voltage events has increased. They have become more stringent the requirements in terms of accuracy of the supply voltage worth their reliability. For the case of CMOS memories operating at 1.5V it is essential to guarantee a variation of the nominal VOUT to within 5% including those arising on the supply voltage during the transients.
Finally, for a voltage regulator operating in space one of the most salient effects are the voltage transients induced on the output by the single events (SET) that may exceed the aforementioned 5% threshold. This can be cause of damage into the circuitry fed downstream.
Among the devices in ST portfolio designed to cope with the mentioned effects there are two voltage regulators, the RHFL4913 and the RHFL6000.
The first one was initially developed for the harsh environment of the Large Hadron Collider. It was tested by the CERN and it was proven that it is able to operate without problems at up to 100Mrad TID at High Dose Rate without problems 1. Subsequent tests performed at low dose rates (expected in space environment), showed that this device is also ELDRS free up to 1Mrad 2. Further tests performed by NASA highlighted also a certain susceptivity to the SET (3) but this issue can be circumvented by the adoption of a properly sized up RC low pass filter put between the regulator output and the load as shown in fig.1 (4).
With the above provision, this regulator is suitable for operating in space. Currently, the RHFL4913 is QMLV qualified
PRRT2 gene variant in a child with dysmorphic features, congenital microcephaly, and severe epileptic seizures: genotype-phenotype correlation?
BACKGROUND: Mutations in Proline-rich Transmembrane Protein 2 (PRRT2) have been primarily associated with individuals presenting with infantile epilepsy, including benign familial infantile epilepsy, benign infantile epilepsy, and benign myoclonus of early infancy, and/or with dyskinetic paroxysms such as paroxysmal kinesigenic dyskinesia, paroxysmal non-kinesigenic dyskinesia, and exercise-induced dyskinesia. However, the clinical manifestations of this disorder vary widely. PRRT2 encodes a protein expressed in the central nervous system that is mainly localized in the pre-synaptic neurons and is involved in the modulation of synaptic neurotransmitter release. The anomalous function of this gene has been proposed to cause dysregulation of neuronal excitability and cerebral disorders. CASE PRESENTATION: We hereby report on a young child followed-up for three years who presents with a spectrum of clinical manifestations such as congenital microcephaly, dysmorphic features, severe intellectual disability, and drug-resistant epileptic encephalopathy in association with a synonymous variant in PRRT2 gene (c.501C > T; p.Thr167Ile) of unknown clinical significance variant (VUS) revealed by diagnostic exome sequencing. CONCLUSION: Several hypotheses have been advanced on the specific role that PRRT2 gene mutations play to cause the clinical features of affected patients. To our knowledge, the severe phenotype seen in this case has never been reported in association with any clinically actionable variant, as the missense substitution detected in PRRT2 gene. Intriguingly, the same mutation was reported in the healthy father: the action of modifying factors in the affected child may be hypothesized. The report of similar observations could extend the spectrum of clinical manifestations linked to this mutation
Volcanic hazard assessment at the Campi Flegrei caldera
Previous and new results from probabilistic approaches based on available
volcanological data from real eruptions of Campi Flegrei, are assembled in a comprehensive
assessment of volcanic hazards at the Campi Flegrei caldera, in order to compare the volcanic
hazards related to the different types of events. Hazard maps based on a very wide set of
numerical simulations, produced using field and laboratory data as input parameters relative
to the whole range of fallout and pyroclastic-flow events and their relative occurrence,
are presented. The results allow us to quantitatively evaluate and compare the hazard
related to pyroclastic fallout and density currents (PDCs) in the Campi Flegrei area and its
surroundings, including the city of Naples.
Due to the dominant wind directions, the hazard from fallout mostly affects the area east of
the caldera, and the caldera itself, with the level of probability and expected thickness decreasing
with distance from the caldera and outside the eastern sectors. The hazard from PDCs
decrease roughly radially with distance from the caldera centre and is strongly controlled by
the topographic relief, which produces an effective barrier to propagation of PDCs to the east
and northeast, areas which include metropolitan Naples. The main result is that the metropolitan
area of Naples would be directly exposed to both fallout and PDCs. Moreover, the
level of probability for critical tephra accumulation by fallout is relatively high, even for
moderate-scale events, while, due to the presence of topographic barriers, the hazard from
PDCs is only moderate and mostly associated with the largest events
Vertex finding in ALICE by the use of silicon pixel layers in the Inner Tracking System
The performance of the Inner Tracking System of the ALICE detector for primary vertex estimation is discussed. A simulation study of the vertex reconstruction in ALICE through the information given by the two pixel layers is reported. Vertex resolution was studied as a function of the nominal vertex location and of the particle multiplicity
The WISSH quasars Project: II. Giant star nurseries in hyper-luminous quasars
Studying the coupling between the energy output produced by the central
quasar and the host galaxy is fundamental to fully understand galaxy evolution.
Quasar feedback is indeed supposed to dramatically affect the galaxy properties
by depositing large amounts of energy and momentum into the ISM. In order to
gain further insights on this process, we study the SEDs of sources at the
brightest end of the quasar luminosity function, for which the feedback
mechanism is supposed to be at its maximum. We model the rest-frame UV-to-FIR
SEDs of 16 WISE-SDSS Selected Hyper-luminous (WISSH) quasars at 1.8 < z < 4.6
disentangling the different emission components and deriving physical
parameters of both the nuclear component and the host galaxy. We also use a
radiative transfer code to account for the contribution of the quasar-related
emission to the FIR fluxes. Most SEDs are well described by a standard
combination of accretion disk+torus and cold dust emission. However, about 30%
of them require an additional emission component in the NIR, with temperatures
peaking at 750K, which indicates the presence of a hotter dust component in
these powerful quasars. We measure extreme values of both AGN bolometric
luminosity (LBOL > 10^47 erg/s) and SFR (up to 2000 Msun/yr). A new relation
between quasar and star-formation luminosity is derived (LSF propto
LQSO^(0.73)) by combining several Herschel-detected quasar samples from z=0 to
4. Future observations will be crucial to measure the molecular gas content in
these systems, probe the impact between quasar-driven outflows and on-going
star-formation, and reveal the presence of merger signatures in their host
galaxies.Comment: 19 pages, 12 figures; Accepted for publication in Astronomy &
Astrophysics on June 13, 201
One year of tropospheri clidar measurements of aerosol extinction and backscatter
The aerosol lidar system operational at IMAA-CNR in Tito Scalo (PZ) (Southern Italy, 40°36'N, 15°44'E, 820 m
above sea level) is part of the EARLINET project. Systematic lidar measurements of aerosol backscatter and
extinction in the troposphere have been performed since May 2000. Aerosol backscatter measurements were
performed at both 355 nm and 532 nm, while aerosol extinction coeffi cient were retrieved from simultaneous N2
Raman backscatter signals at 386.6 nm. The observations were performed on a regular schedule of two night time
measurements per week (around sunset) and one daytime measurement per week (around 13:00 UTC). Furthermore,
special observations concerning Saharan dust outbreaks have been carried out. Starting in May 2000 the lidar
measurements performed in Tito Scalo have been collected and analysed. Preliminary results regarding the fi rst
year of measurements are reported. In particular, the evolution of the aerosol integrated backscatter and extinction
as well as of the mean value of the lidar ratio in the whole aerosol layer is reported. Results show clear evidence
of seasonal variation of the observed parameters, with higher values and greater variability during summertime
The identification of dust heating mechanisms in nearby galaxies using Herschel 160/250 and 250/350 micron surface brightness ratios
We examined variations in the 160/250 and 250/350 micron surface brightness
ratios within 24 nearby (<30 Mpc) face-on spiral galaxies observed with the
Herschel Space Observatory to identify the heating mechanisms for dust emitting
at these wavelengths. The analysis consisted of both qualitative and
quantitative comparisons of the 160/250 and 250/350 micron ratios to H alpha
and 24 micron surface brightnesses, which trace the light from star forming
regions, and 3.6 micron emission, which traces the light from the older stellar
populations of the galaxies. We find broad variations in the heating mechanisms
for the dust. In one subset of galaxies, we found evidence that emission at
<=160 microns (and in rare cases potentially at <=350 microns) originates from
dust heated by star forming regions. In another subset, we found that the
emission at >=250 microns (and sometimes at >=160 microns) originates from dust
heated by the older stellar population. In the rest of the sample, either the
results are indeterminate or both of these stellar populations may contribute
equally to the global dust heating. The observed variations in dust heating
mechanisms does not necessarily match what has been predicted by dust emission
and radiative transfer models, which could lead to overestimated dust
temperatures, underestimated dust masses, false detections of variability in
dust emissivity, and inaccurate star formation rate measurements.Comment: Accepted for publication in MNRA
Tracking inside the ALICE Inner Tracking System
One of the main purposes of the ALICE Inner Tracking System (ITS) is to improve the resolution of the track parameters found in the main ALICE tracker detector, the Time Projector Chamber (TPC). Some results about tracking efficiency and resolution of track parameters obtained with a tracking code, based on the Kalman filter algorithm are presented
- …