86,814 research outputs found
A galaxy overdensity at z = 0.401 associated with an X-ray emitting structure of warm-hot intergalactic medium
No full textWe present the results of spectroscopic observations of galaxies associated with the diffuse X-ray emitting structure discovered by Zappacosta et al. (2002, A&A, 394, 7). After measuring the redshifts of 161 galaxies, we confirm an overdensity of galaxies with projected dimensions of at least 2 Mpc, determine its spectroscopic redshift in z = 0.401 ± 0.002, and show that it is spatially coincident with the diffuse X-ray emission. This confirms the original claim that this X-ray emission has an extragalactic nature and is due to the warm-hot intergalactic medium (WHIM). We used this value of the redshift to compute the temperature of the emitting gas. The resulting value depends on the metallicity that is assumed for the IGM, and is constrained to be between 0.3 and 0.6 keV for metallicities between 0.05 and 0.3 solar, in good agreement with the expectations from the WHIM. © ESO 2007
Rapporto sulle attività del Sistema Nazionale a rete per la Protezione dell’Ambiente nell’anno 2022 (art. 10, comma 3, l. n. 132/2016), Rapporto annuale 2023
No full textIl Rapporto sulle attività del Sistema Nazionale a rete per la Protezione dell'Ambiente (SNPA) - ai sensi dell' art 10, comma 3, l. n. 132/2016 - rappresenta in forma organica e generale le principali attività svolte dal Sistema nell’anno 2022, con specifico riferimento ai risultati raggiunti, al coordinamento tecnico e all’attività di uniformazione richiesta dalla legge istitutiva del SNPA.
Il Rapporto, in particolare: relaziona, nelle more dell’emanazione del DPCM sui Livelli Essenziali delle Prestazioni Tecniche Ambientali (LEPTA), in merito alle principali attività realizzate nell’ambito del Programma Triennale delle attività SNPA
2021-2023, al coordinamento tecnico e all’attività di uniformazione svolta e, in generale, allo stato di attuazione della
l. n. 132/2016. Inoltre fornisce elementi sull’azione del Consiglio SNPA per il progressivo miglioramento del funzionamento della rete e per il consolidamento dell’azione e dell’immagine del Sistema come istituzione e per la società civile
Augmented gyro-stellar model in the presence of measurements delay
No full textIn recent years, the tendency to decrease satellites’ size and costs has turned into more stringent requirements for lesser-performing sensors. The study of attitude estimation for micro-sat under measurements’ date errors in a gyro-stellar configuration is here presented. An augmented model is studied in which both the star tracker's and gyro's data are used as update measurements for the feed of the multiplicative extended Kalman filter. The analyzed configuration presents high-levels of gyro's noises. The augmented model successfully reduced the angular rate's estimation error compared to the well-established "Replacement mode" model of Farrenkopf’s equations. The filter is then modified to compensate the date error between the rate and attitude measurements by means of different algorithms, which capabilities are analyzed in a parametric study of the performances under variation of sampling time and measurements' delay. The compensation algorithms proved to be successful, but the performances are strictly dependent on the gyro's capabilities. The results are then exploited for the design of a filter that combines the two aspects and is applied with a star tracker and a rate-gyro readily available in the marke
Serafino Zappacosta: An Enlightened Mentor and Educator
No full textWith this article, the authors aim to honor the memory of Serafino Zappacosta, who had been their mentor during the early years of their career in science. The authors discuss how the combination of Serafino Zappacosta's extraordinary commitment to teaching and passion for science created a fostering educational environment that led to the creation of the “Ruggero Ceppellini Advanced School of Immunology.” The review also illustrates how the research on the MHC and the inspirational scientific context in the Zappacosta's laboratory influenced the authors' early scientific interests, and subsequent professional work as immunologists
Surface topology of Minibody by selective chemical modifications and mass spectrometry
No full textThe surface topology of the Minibody, a small de novo-designed beta-protein, has been probed by a strategy that combines selective chemical modification with a variety of reagents and mass spectrometric analysis of the modified fragments. Under appropriate conditions, the susceptibility of individual residues primarily depends on their surface accessibility so that their relative reactivities can be correlated with their position in the tertiary structure of the protein. Moreover, this approach provides information on interacting residues, since intramolecular interactions might greatly affect the reactivity of individual side chains by altering their pKa values. The results of this study indicate that, while overall the Minibody model is correct, the beta-sheet formed by the N- and C-terminal segments is most likely distorted. This is also in agreement with previous results that were obtained using a similar approach where mass spectrometry was used to identify Minibody fragments from limited proteolysis (Zappacosta F, Pessi A, Bianchi E, Venturini S, Sollazzo M, Tramontano A, Ma?ino G, Pucci P. 1996. Probing the tertiary structure of proteins by limited proteolysis and mass spectrometry: The case of Minibody. Protein Sci 5:802-813). The chemical modification approach, in combination with limited proteolysis procedures, can provide useful, albeit partial, structural information to complement simulation techniques. This is especially valuable when, as in the Minibody case, an NMR and/or X-ray structure cannot be obtained due to insufficient solubility of the molecule
Identification of C-terminally truncated forms of beta-lactoglobulin in milk bovine whey by two-dimensional gel electrophoresis coupled to mass spectrometry
No full textConstraining the geometry of the nuclear wind in PDS 456 using a novel emission model
No full textOutflows from active galactic nuclei (AGN) are often invoked to explain the
co-evolution of AGN and their host galaxies, and the scaling relations between
the central black hole mass and the bulge velocity dispersion. Nuclear winds
are often seen in the X-ray spectra through Fe K shell transitions and some of
them are called ultra fast outflows (UFOs) due to their high velocities, up to
some fractions of the speed of light. If they were able to transfer some
percentage of the AGN luminosity to the host galaxy, this might be enough to
trigger an efficient feedback mechanism. We aim to establish new constraints on
the covering fraction and on the kinematic properties of the UFO in the
powerful (L(bol) ~ 10^(47) erg/s) quasar PDS 456, an established Rosetta stone
for studying AGN feedback from disk winds. This will allow us to estimate the
mass outflow rate and the energy transfer rate of the wind, which are key
quantities to understand the potential impact on the host galaxy. We analyze
two sets of simultaneous XMM-Newton and NuSTAR observations taken in September
2013 and reported in Nardini et al. (2015) as having similar broadband spectral
properties. We fit the Fe K features with a P-Cygni profile between 5 and 14
keV, using a novel Monte Carlo model for the WINd Emission (WINE). We find an
outflow velocity ranging from 0.17 to 0.28 c, with a mean value of 0.23 c. We
obtain an opening angle of the wind of 71(+13,-8) deg and a covering fraction
of 0.7(+0.2,-0.3), suggesting a wide-angle outflow. We check the reliability of
the WINE model by performing extensive simulations of joint XMM-Newton and
NuSTAR observations. Furthermore, we test the accuracy of the WINE model in
recovering the geometrical properties of UFOs by simulating observations with
the forthcoming X-ray observatory ATHENA
Post-translational modifications in aspartate aminotransferase from Sulfolobus solfataricus. Detection of N-epsilon-methyllysines by mass spectrometry.
No full textAdvanced mass spectrometric procedures have been extensively used to provide an accurate structural characterization of aspartate aminotransferase from Sulfolobus solfataricus. The amino acid sequence of this enzyme had previously been deduced from the DNA sequence. The accurate molecular mass of the protein, determined using electrospray mass spectrometry, demonstrated that the amino acid sequence deduced was correct and ruled out the possible presence of large covalent modifications which had been postulated to fit the much higher molecular mass obtained from previous SDS/PAGE experiments. The definition of the entire primary structure of aspartate aminotransferase from S. solfataricus was achieved by exploiting a new mass spectrometric mapping strategy. Initially, the molecular mass of relatively large protein fragments produced by CNBr hydrolysis was accurately determined using electrospray mass spectrometry. The protein regions where structural modifications had occurred were easily identified from their anomalous mass values. The corresponding CNBr fragments were then subdigested with suitable proteases and the resulting peptide mixtures were analysed by fast-atom-bombardment mass spectrometry. This mapping approach led to the detection of two partially modified lysine residues at positions 202 and 384, which had been converted to their N-epsilon-methyl derivatives to a substoichiometric extent
ATP-sensitive Potassium Channel Subunits in Neuroinflammation: Novel Drug Targets in Neurodegenerative Disorders
No full textArachidonic acids and its metabolites modulate plenty of ligand-gated, voltage-depen-dent ion channels, and metabolically regulated potassium channels including ATP-sensitive potassium channels (KATP). KATP channels are hetero-multimeric complexes of sulfonylureas receptors (SUR1, SUR2A or SUR2B) and the pore-forming subunits (Kir6.1 and Kir6.2) likewise expressed in the pre-post synapsis of neurons and inflammatory cells, thereby affecting their proliferation and activity. KATP channels are involved in amyloid-β (Aβ)-induced pathology, therefore emerging as therapeutic targets against Alzheimer’s and related diseases. The modulation of these channels can represent an innovative strategy for the treatment of neurodegenerative disorders; nevertheless, the currently available drugs are not selective for brain KATP channels and show contrasting effects. This phenomenon can be a consequence of the multiple physiological roles of the different vari-eties of KATP channels. Openings of cardiac and muscular KATP channel subunits, are protective against caspase-dependent atrophy in these tissues and some neurodegenerative disorders, whereas in some neuroinflammatory diseases, benefits can be obtained through the inhibition of neuronal KATP channel subunits. For example, glibenclamide exerts an anti-inflammatory effect in respira-tory, digestive, urological, and central nervous system (CNS) diseases, as well as in ischemia-reper-fusion injury associated with abnormal SUR1-Trpm4/TNF-α or SUR1-Trpm4/ Nos2/ROS signal-ing. Despite this strategy being promising, glibenclamide may have limited clinical efficacy due to its unselective blocking action of SUR2A/B subunits also expressed in cardiovascular apparatus with pro-arrhythmic effects and SUR1 expressed in pancreatic beta cells with hypoglycemic risk. Alternatively, neuronal selective dual modulators showing agonist/antagonist actions on KATP channels can be an option
Probing the Dark Matter and Gas Fraction in Relaxed Galaxy Groups with X-ray observations from Chandra and XMM
No full textWe present radial mass profiles within 0:3rvir for 16 relaxed galaxy groups—poor clusters (kT range 1Y3 keV )
selected for optimal mass constraints from the Chandra and XMM-Newton data archives. After accounting for the mass
of hot gas, the resulting mass profiles are described well by a two-component model consisting of dark matter, represented
by an NFW model, and stars from the central galaxy. The stellar component is required only for eight systems,
for which reasonable stellar mass-to-light ratios (M/LK) are obtained, assuming a Kroupa IMF. Modifying the
NFW dark matter halo by adiabatic contraction does not improve the fit and yields systematically lower M/LK.
In contrast to previous results for massive clusters, we find that the NFW concentration parameter (cvir) for groups
decreases with increasing Mvir and is inconsistent with no variation at the 3 level. The normalization and slope of the
cvir-Mvir relation are consistent with the standard CDM cosmological model with 8 1⁄4 0:9 (considering a 10% bias
for early forming systems). The small intrinsic scatter measured about the cvir-Mvir relation implies that the groups
represent preferentially relaxed, early forming systems. The mean gas fraction ( f 1⁄4 0:05 0:01) of the groups measured
within an overdensity 1⁄4 2500 is lower than for hot, massive clusters, but the fractional scatter (f /f 1⁄4 0:2)
for groups is larger, implying a greater impact of feedback processes on groups, as expected
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