862 research outputs found
Totally asymptotically free trinification
Motivated by new ideas about the Higgs mass naturalness problem, we present
realistic TeV-scale extensions of the Standard Model, into the gauge group
SU(3)_L x SU(3)_R x SU(3)_c, such that all gauge, Yukawa and quartic couplings
can be extrapolated up to infinite energy. Three generations of chiral fermions
and Higgses are needed, as well as some extra fermion.Comment: 15 pages. The ancillary Mathematica file shows a sample of results.
v2: final version accepted by JHE
Vehicle-to-Grid and ancillary services:a profitability analysis under uncertainty
The rapid and massive diffusion of electric vehicles poses new challenges to
the electric system, which must be able to supply these new loads, but at the
same time opens up new opportunities thanks to the possible provision of
ancillary services. Indeed, in the so-called Vehicle-to-Grid (V2G) set-up, the
charging power can be modulated throughout the day so that a fleet of vehicles
can absorb an excess of power from the grid or provide extra power during a
shortage.To this end, many works in the literature focus on the optimization of
each vehicle daily charging profiles to offer the requested ancillary services
while guaranteeing a charged battery for each vehicle at the end of the day.
However, the size of the economic benefits related to the provision of
ancillary services varies significantly with the modeling approaches, different
assumptions, and considered scenarios. In this paper we propose a profitability
analysis with reference to a recently proposed framework for V2G optimal
operation in presence of uncertainty. We provide necessary and sufficient
conditions for profitability in a simplified case and we show via simulation
that they also hold for the general case.Comment: Accepted by IFAC for publication under a Creative Commons Licence
CC-BY-NC-N
Detection of Faint BLR Components in the Starburst/Seyfert Galaxy NGC 6221 and Measure of the Central BH Mass
In the last decade, using single epoch virial based techniques in the optical
band, it has been possible to measure the central black hole mass on large AGN1
samples. However these measurements use the width of the broad line region as a
proxy of the virial velocities and are therefore difficult to be carried out on
those obscured (type 2) or low luminosity AGN where the nuclear component does
not dominate in the optical. Here we present the optical and near infrared
spectrum of the starburst/Seyfert galaxy NGC 6221, observed with X-shooter/VLT.
Previous observations of NGC 6221 in the X-ray band show an absorbed (N_H=8.5
+/- 0.4 x 10^21 cm^-2) spectrum typical of a type 2 AGN with luminosity
log(L_14-195 keV) = 42.05 erg/s, while in the optical band its spectrum is
typical of a reddened (A_V=3) starburst. Our deep X-shooter/VLT observations
have allowed us to detect faint broad emission in the H_alpha, HeI and Pa_beta
lines (FWHM ~1400-2300 km/s) confirming previous studies indicating that NGC
6221 is a reddened starburst galaxy which hosts an AGN. We use the measure of
the broad components to provide a first estimate of its central black hole mass
(M_BH = 10^(6.6 +/- 0.3) Msol, lambda_Edd=0.01-0.03), obtained using recently
calibrated virial relations suitable for moderately obscured (N_H<10^24 cm^-2)
AGN.Comment: 13 pages, 3 figures, 1 table. Published in Frontiers in Astronomy and
Space Science
Calcifediol Rather Than Cholecalciferol for a Patient Submitted to Malabsortive Bariatric Surgery: A Case Report
Vitamin D deficiency following malabsorptive bariatric surgery can lead to osteomalacia. We report a patient with severe vitamin D deficiency following malabsorptive bariatric surgery successfully treated with calcifediol but not cholecalciferol. A 40-year-old woman, submitted to biliopancreatic diversion 20 years before and chronically treated with 50,000 IU cholecalciferol weekly, was admitted to our Endocrine Unit because of severe lower back pain, muscle weakness, and generalized muscular hypotrophy, associated with hypocalcemia and elevated PTH levels. Initial evaluation revealed low serum albumin, low albumin-corrected serum calcium (7.36 mg/dL), high serum PTH (240 pg/mL), bone-specific alkaline phosphatase (125 μg/L) and 1,25-dihydroxyvitamin D (112 pg/mL) concentrations, undetectable serum 25-hydroxyvitamin D (<7 ng/mL), and evidence of reduced liver function. Bone mineral density was markedly low. Normocalcemia was initially restored with intravenous albumin and calcium gluconate. Treatment with calcitriol (0.5 μg three times daily) and oral calcium carbonate (1000 mg daily) was simultaneously started and cholecalciferol was replaced with calcifediol [125 μg (5000 IU) daily)]. During follow-up the calcifediol dose was progressively tapered to 25 μg (1000 IU) daily and the calcitriol dose was progressively reduced and finally withdrawn. Serum albumin and other biochemical parameters normalized, bone mineral density significantly increased, and the patient's clinical conditions progressively improved, with a substantial recovery of autonomy. Serum vitamin D binding protein at the last observation was in the normal range. Our data suggest that calcifediol might be more efficacious than cholecalciferol for prevention and treatment of vitamin D deficiency in patients treated by malabsorptive bariatric surgery
How Do University Student Cyclists Ride? The Case of University of Bologna
In a general urban planning context, in which sustainable active mobility progressively takes
up increasing attention, studies of cyclists’ attitudes and behaviors represent a relevant step to help
any enhancing measures for urban cycling. Among different categories, university student cyclists
represent a still unidentified class, despite the relevant impacts in terms of mass and variability of
attitudes in urban areas. The novelty of this paper is to propose an innovative overview on the specific
category of university student cyclists. The integrated methodology, based on direct observation
through GPS detection, GIS processing, and qualitative survey, permits the evaluation of some
interesting issues related to students’ propensity to cycling and their mobility patterns. The approach
finds relevance in speed, frequency of movements, routing, and related infrastructure preferences.
The methodology has been applied to a sample of more than 300 students of the University of
Bologna who were allowed an original university-designed bicycle from February 2021 to June
2021. The analysis was applied in the Bologna urban area and allowed the evaluation of students’
preferences of using existing cycle paths, when available, the limited relevance of speed factors, the
main distribution of commuter journeys concentrated in the main avenues directed to city center,
and other behaviors
Unveiling the Socio-Economic Fragility of a Major Urban Touristic Destination through Open Data and Airbnb Data: The Case Study of Bologna, Italy
In the last decades, tourism in urban areas has been constantly increasing. The need for short-term accommodations has been coupled with the emergence of internet-based services, which makes it easier to match demand (i.e., tourists) and supply (i.e., housing). As a new mass tourist destination, Bologna, Italy, has been experiencing tensions between tourists and long-, mid-, or short-term renters. The possibility of easy profits for lessees has led to an increase in such housing, which can be rented out either for touristic reasons or not. This paper aims to unveil the contribution of short-term rental accommodations in distorting the real estate market and conditioning social and economic inequalities. To do this, multiple linear regression analyses (MLR) were performed between accommodation density, real estate market information, and indicators about social, economic, and demographic vulnerability and fragility. Analyses were based on official open data and datasets from a major web-based hospitality exchange platform, i.e., Airbnb, able to provide information on registered accommodations, e.g., type, characteristics (e.g., number of bedrooms and average rating), and location. Outputs of the analyses reveal the role of Airbnb in both rental market and social, economic, and demographic vulnerability and fragility and, hence, can be a solid tool for public policies, both housing- and tourism-related
Extending Virial Black Hole Mass Estimates to Low-Luminosity or Obscured AGN: the cases of NGC 4395 and MCG -01-24-012
In the last decade, using single epoch (SE) virial based spectroscopic
optical observations, it has been possible to measure the black hole (BH) mass
on large type 1 Active Galactic Nuclei (AGN) samples. However this kind of
measurements can not be applied on those obscured type 2 and/or low luminosity
AGN where the nuclear component does not dominate in the optical. We have
derived new SE relationships, based on the FWHM and luminosity of the broad
line region component of the Pabeta emission line and/or the hard X-ray
luminosity in the 14-195 keV band, which have the prospect of better working
with low luminosity or obscured AGN. The SE relationships have been calibrated
in the 10^5-10^9 M_sol mass range, using a sample of AGN whose BH masses have
been previously measured using reverberation mapping techniques. Our tightest
relationship between the reverberation-based BH mass and the SE virial product
has an intrinsic spread of 0.20 dex. Thanks to these SE relations, in agreement
with previous estimates, we have measured a BH mass of M_BH =1.7^+1.3_-0.7 X
10^5 M_sol for the low luminosity, type 1, AGN NGC 4395 (one of the smallest
active galactic BH known). We also measured, for the first time, a BH mass of
M_BH = 1.5^+1.1_-0.6 X 10^7 M_sol for the Seyfert 2 galaxy MCG -01-24-012.Comment: 10 pages, 7 figures. Accepted by MNRA
NGC 1275: An Outlier of the Black Hole-Host Scaling Relations
The active galaxy NGC 1275 lies at the center of the Perseus cluster of
galaxies, being an archetypal BH-galaxy system that is supposed to fit
well with the M-BH-host scaling relations obtained for quiescent
galaxies. Since it harbors an obscured AGN, only recently our group has
been able to estimate its black hole mass. Here our aim is to pinpoint
NGC 1275 on the less dispersed scaling relations, namely the
M-BH-sigma(*) and M-BH - L-bul planes. Starting from our previous work
(Ricci et al., 2017a), we estimate that NGC 1275 falls well outside the
intrinsic dispersion of the M-BH-sigma(*) plane being 1.2 dex (in
black hole mass) displaced with respect to the scaling relations. We
then perform a 2D morphological decomposition analysis on Spitzer/IRAC
images at 3.6 mu m and find that, beyond the bright compact nucleus that
dominates the central emission, NGC 1275 follows a de Vaucouleurs
profile with no sign of significant star formation nor clear merger
remnants. Nonetheless, its displacement on the M-BH - L-3.6,L-bul plane
with respect to the scaling relation is as high as observed in the
M-BH-sigma(*). We explore various scenarios to interpret such
behaviors, of which the most realistic one is the evolutionary pattern
followed by NGC 1275 to approach the scaling relation. We indeed
speculate that NGC 1275 might be a specimen for those galaxies in which
the black holes adjusted to its host
X-ray redshifts for obscured AGN: a case study in the J1030 deep field
We present a procedure to constrain the redshifts of obscured ( cm) Active Galactic Nuclei (AGN) based on low-count statistics
X-ray spectra, which can be adopted when photometric and/or spectroscopic
redshifts are unavailable or difficult to obtain. We selected a sample of 54
obscured AGN candidates on the basis of their X-ray hardness ratio, ,
in the Chandra deep field (479 ks, 335 arcmin) around the QSO
SDSS J1030+0524. The sample has a median value of net counts in the
0.5-7 keV energy band. We estimate reliable X-ray redshift solutions taking
advantage of the main features in obscured AGN spectra, like the Fe 6.4 keV
K emission line, the 7.1 keV Fe absorption edge and the
photoelectric absorption cut-off. The significance of such features is
investigated through spectral simulations, and the derived X-ray redshift
solutions are then compared with photometric redshifts. Both photometric and
X-ray redshifts are derived for 33 sources. When multiple solutions are derived
by any method, we find that combining the redshift solutions of the two
techniques improves the rms by a factor of two. Using our redshift estimates
(), we derived absorbing column densities in the
range cm and absorption-corrected, 2-10 keV
rest-frame luminosities between and erg s, with
median values of cm and erg s, respectively. Our results suggest that
the adopted procedure can be applied to current and future X-ray surveys, for
sources detected only in the X-rays or that have uncertain photometric or
single-line spectroscopic redshifts.Comment: 22 pages, 18 figure
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