4,799 research outputs found
GRB Observed by IBIS/PICsIT in the MeV Energy Range
We present the preliminary results of a systematic search for GRB and other
transients in the publicly available data for the IBIS/PICsIT (0.2-10 MeV)
detector on board INTEGRAL. Lightcurves in 2-8 energy bands with time
resolution from 1 to 62.5 ms have been collected and an analysis of spectral
and temporal characteristics has been performed. This is the nucleus of a
forthcoming first catalog of GRB observed by PICsIT.Comment: 6 pages, 3 figures. Poster presented at COSPAR 2008. Advaces in Space
Research, accepted for publicatio
Experimental techniques in hadron spectroscopy
Quantum Chromodynamics (QCD) is the theory of the strong interaction, but the properties of the hadrons cannot be directly calculated from the QCD Lagrangian and alternative approaches are then used. In order to test the different models, precise measurements of hadron properties are of extreme importance. This is the main motivation for the hadron spectroscopy experimental program carried out since many years with different probes and different detectors. A survey of some recent results in the field is here presented and commented, together with the opportunities offered by the forthcoming experimental programs
Ethylene-propene copolymerization. Monomer reactivity and reaction mechanism
The relative reactivity of ethylene and propene in the first insertion steps of Ziegler-Natta copolymerization has been evaluated by analyzing via 13CNMR the %enriched end groups of copolymer fractionsofdifferentstereoregularity. Somepossibleinferencesconcerningreactionmechanismarereported
MagicMuseum: Team-based Experiences in Interactive Smart Spaces for Cultural Heritage Education
MagicMuseum is a set of team-based, immersive, full-body activities for Cultural Heritage Education of primary school children. MagicMuseum exploits the interactive and multisensory capability of the Magic Room, an indoor smart space equipped with IoT-enriched components such as floor and wall projections, smart lighting, music and sound, motion and gesture sensors, and smart objects. The paper describes MagicMuseum and briefly reports an exploratory study involving 22 children at a local primary school
Antioxidant and Angiotensin I-Converting Enzyme (ACE) Inhibitory Peptides Obtained from Alcalase Protein Hydrolysate Fractions of Hemp ( Cannabis sativa L.) Bran
Proteins from hemp bran (HPB), a byproduct of the hemp seed food-processing chain, were chemically extracted, hydrolyzed by Alcalase, and separated by membrane ultrafiltration into four fractions (MW <1, 1–3, 3–5, and >5 kDa). The antioxidant and antihypertensive properties of the initial extract and the fractions were evaluated by in vitro assays for their ability to scavenge radical species, bind with metal ions, reduce ferric ions, and inhibit angiotensin-converting enzyme (ACE) activity. Bioactive peptides were identified by high-resolution mass spectrometry and sequence comparison with BIOPEP and BioPep DB databases. The hydrolysate was strongly antioxidant and ACE-inhibiting; the most bioactive peptides were further concentrated by ultrafiltration. Of the 239 peptides identified, 47 (12 antioxidant and 35 ACE-inhibitory) exhibited structural features correlated with the specific bioactivity. These results highlight the promise of hydrolysate and size-based HPB fractions as natural functional ingredients for the food or pharmaceutical industry
Antioxidant and Angiotensin I-Converting Enzyme (ACE) Inhibitory Peptides Obtained from Alcalase Protein Hydrolysate Fractions of Hemp (Cannabis sativa L.) Bran
Proteins from hemp bran (HPB), a byproduct of the hemp seed food-processing chain, were chemically extracted, hydrolyzed by Alcalase, and separated by membrane ultrafiltration into four fractions (MW <1, 1-3, 3-5, and >5 kDa). The antioxidant and antihypertensive properties of the initial extract and the fractions were evaluated by in vitro assays for their ability to scavenge radical species, bind with metal ions, reduce ferric ions, and inhibit angiotensin-converting enzyme (ACE) activity. Bioactive peptides were identified by high-resolution mass spectrometry and sequence comparison with BIOPEP and BioPep DB databases. The hydrolysate was strongly antioxidant and ACE-inhibiting; the most bioactive peptides were further concentrated by ultrafiltration. Of the 239 peptides identified, 47 (12 antioxidant and 35 ACE-inhibitory) exhibited structural features correlated with the specific bioactivity. These results highlight the promise of hydrolysate and size-based HPB fractions as natural functional ingredients for the food or pharmaceutical industry
Intermolecular interactions in the TMEM16A dimer controlling channel activity
TMEM16A and TMEM16B are plasma membrane proteins with Ca2+ -dependent Cl- channel function. By replacing the carboxy-terminus of TMEM16A with the equivalent region of TMEM16B, we obtained channels with potentiation of channel activity. Progressive shortening of the chimeric region restricted the "activating domain" to a short sequence close to the last transmembrane domain and led to TMEM16A channels with high activity at very low intracellular Ca2+ concentrations. To elucidate the molecular mechanism underlying this effect, we carried out experiments based on double chimeras, Forster resonance energy transfer, and intermolecular cross-linking. We also modeled TMEM16A structure using the Nectria haematococca TMEM16 protein as template. Our results indicate that the enhanced activity in chimeric channels is due to altered interaction between the carboxy-terminus and the first intracellular loop in the TMEM16A homo-dimer. Mimicking this perturbation with a small molecule could be the basis for a pharmacological stimulation of TMEM16A-dependent Cl- transport
Why Some People Discount More than Others: Baseline Activation in the Dorsal PFC Mediates the Link between COMT Genotype and Impatient Choice
Individuals differ widely in how steeply they discount future rewards. The sources of these stable individual differences in delay discounting (DD) are largely unknown. One candidate is the COMT Val158Met polymorphism, known to modulate prefrontal dopamine levels and affect DD. To identify possible neural mechanisms by which this polymorphism may contribute to stable individual DD differences, we measured 73 participants’ neural baseline activation using resting electroencephalogram (EEG). Such neural baseline activation measures are highly heritable and stable over time, thus an ideal endophenotype candidate to explain how genes may influence behavior via individual differences in neural function. After EEG-recording, participants made a series of incentive-compatible intertemporal choices to determine the steepness of their DD. We found that COMT significantly affected DD and that this effect was mediated by baseline activation level in the left dorsal prefrontal cortex (DPFC): (i) COMT had a significant effect on DD such that the number of Val alleles was positively correlated with steeper DD (higher numbers of Val alleles means greater COMT activity and thus lower dopamine levels). (ii) A whole-brain search identified a cluster in left DPFC where baseline activation was correlated with DD; lower activation was associated with steeper DD. (iii) COMT had a significant effect on the baseline activation level in this left DPFC cluster such that a higher number of Val alleles was associated with lower baseline activation. (iv) The effect of COMT on DD was explained by the mediating effect of neural baseline activation in the left DPFC cluster. Our study thus establishes baseline activation level in left DPFC as salient neural signature in the form of an endophenotype that mediates the link between COMT and DD
On the Angular Resolution of the AGILE gamma-ray imaging detector
We present a study of the Angular Resolution of the AGILE gamma-ray imaging
detector (GRID) that is operational in space since April 2007. The AGILE
instrument is made of an array of 12 planes each equipped with a Tungsten
converter and Silicon micros trip detectors and is sensitive in the energy
range 50 MeV - 10 GeV. Among the space instruments devoted to gamma-ray
astrophysics, AGILE uniquely exploits an analog readout system with dedicated
electronics coupled with Silicon detectors. We show the results of Monte Carlo
simulations carried out to reproduce the gamma-ray detection by the GRID, and
we compare them to in-flight data. We use the Crab (pulsar + Nebula) system for
discussion of real data performance, since its E^{-2} energy spectrum is
representative of the majority of gamma-ray sources. For Crab-like spectrum
sources, the GRID angular resolution (FWHM of ~4deg at 100 MeV; ~0.8deg at 1
GeV; ~0.9deg integrating the full energy band from 100 MeV to tens of GeV) is
stable across a large field of view, being characterized by a flat response up
to 30deg off-axis. A comparison of the angular resolution obtained by the two
operational gamma-ray instruments, AGILE-GRID and Fermi-LAT, is interesting in
view of future gamma-ray missions, that are currently under study. The two
instruments exploit different detector configurations affecting the angular
resolution: the former being optimized in the readout and track reconstruction
especially in the low-energy band, the latter in terms of converter thickness
and power consumption. We show that, despite these differences, the angular
resolution of both instruments is very similar between 100 MeV and a few GeV.Comment: 19 pages, 8 figures, accepted for publication in Ap
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