2,147 research outputs found
Searches for new physics using dijet events at the LHC
We present a concise review of the plans of the ATLAS and CMS collaborations
to search for new physics using dijet events. The inclusive cross section as a
function of jet p, the dijet mass distribution and the dijet ratio's CMS
techniques are presented together with their potential of discovery with a
focus on the integrated luminosities of 10, 100 and 1000 pb.
Analogously, the inclusive jet and angular distribution searches in the dijet
channel from ATLAS are presented together with the potential of discovery given
in terms of needed integrated luminosity.Comment: Talk given at the "Rencontres de Moriond" QCD 200
The Italian version of the Thinking About Life Experiences Questionnaire and its relationship with gender, age, and life events on Facebook
The present study provided a cross-cultural validation of the Thinking About Life Experiences Scale-revised (TALE-R) in an Italian sample of Facebook users (n = 492; female = 378; male = 114; mean age 26.1) to test for replication and universality of the TALE-R three-factor model. Furthermore, it explored the interrelations among gender, age, the scores at the TALE-R and the frequency of posting textual/visual information about individuals' life events on Facebook. Results at exploratory and confirmatory factor analysis gave empirical support to both of a tripartite model for the functions of autobiographical memory (i.e., directive-behavior, social-bonding, and self-continuity) and measurement invariance of this three-factor model across gender and age. Further results at linear correlation and regression analyses showed that directive-behavior and self-continuity functions of autobiographical memory are significantly related to the ways people use Facebook for personal documentation. Age differences more than gender influence this association. Discussion and conclusion reported both theoretical and empirical implications of the findings of the study
Chromo-field flux sheets as confining gauge field configurations in the SU(N) Euclidean Yang-Mills theory in the Landau gauge
For the four-dimensional SU(N) Euclidean Yang-Mills theory in the Landau
gauge, we present two sets of gauge field configurations that satisfy the
Euclidean equations of motion. These configurations generate four-dimensional
chromo-field flux sheets whose spatial cross sections are three-dimensional
chromo-field flux tubes. In lattice simulations, they may be detected as center
vortices. The first set of gauge field configurations generates chromo-electric
flux tubes that should contribute to a chromo-electric flux tube between two
static color charges. The string tension for two static color charges in
representation r then naturally satisfies the Casimir scaling. Applying a gauge
transformation to this set of gauge field configurations, we can transform them
into those in the maximal Abelian gauge. These transformed configurations
generate chromo-electric flux tubes that should contribute to those observed
between two static quarks in lattice simulations performed in the maximal
Abelian gauge. The second set of gauge field configurations generates
chromo-magnetic flux tubes. When rotated in a plane that includes the
temporal-axis and is perpendicular to the flux tube axis, the rotated gauge
field configuration generates a chromo-electric flux tube and should contribute
to the chromo-electric flux tubes observed in lattice simulations in the Landau
gauge. We also argue that when regulated on a lattice, any of the flux sheet
gauge field configuration with a finite flux sheet thickness is located on the
Gribov horizon in the infinite lattice volume limit. We thus suggest that these
sets of gauge field configurations contribute significantly to the low energy
properties of QCD, particularly the quark confinement.Comment: 31 pages. The version to appear in Physical Review
Sulphur abundance determinations in star-forming regions-I: Ionization Correction Factor
In the present work we used a grid of photoionization models combined with
stellar population synthesis models to derive reliable Ionization Correction
Factors (ICFs) for the sulphur in star-forming regions. These models cover a
large range of nebular parameters and yielding ionic abundances in consonance
with those derived through optical and infrared observational data of
star-forming regions. From our theoretical ICFs, we suggested an {\alpha} value
of 3.27 in the classical Stasinska formulae. We compared the total sulphur
abundance in the gas phase of a large sample of objects by using our
Theoretical ICF and other approaches. In average, the differences between the
determinations via the use of the different ICFs considered are similar to the
uncertainties in the S/H estimations. Nevertheless, we noted that for some
objects it could reach up to about 0.3 dex for the low metallicity regime.
Despite of the large scatter of the points, we found a trend of S/O ratio to
decrease with the metallicity, independently of the ICF used to compute the
sulphur total abundance.Comment: Accepted for publication in MNRAS, 21 pages, 8 figures, 5 table
High velocity blue-shifted FeII absorption in the dwarf star-forming galaxy PHL293B: Evidence for a wind driven supershell?
X-shooter and ISIS WHT spectra of the starforming galaxy PHL 293B also known
as A2228-00 and SDSS J223036.79-000636.9 are presented in this paper.
We find broad (FWHM = 1000km/s) and very broad (FWZI = 4000km/s) components
in the Balmer lines, narrow absorption components in the Balmer series
blueshifted by 800km/s, previously undetected FeII multiplet (42) absorptions
also blueshifted by 800km/s, IR CaII triplet stellar absorptions consistent
with [Fe/H] < -2.0 and no broad components or blushifted absorptions in the HeI
lines. Based on historical records, we found no optical variability at the 5
sigma level of 0.02 mag between 2005 and 2013 and no optical variability at the
level of 0.1mag for the past 24 years.
The lack of variability rules out transient phenomena like luminous blue
variables or SN IIn as the origin of the blue shifted absorptions of HI and
FeII. The evidence points to either a young and dense expanding supershell or a
stationary cooling wind, in both cases driven by the young cluster wind.Comment: Accepted for publication in MNRAS; 15 pages, 10 figure
Interaction effects on galaxy pairs with Gemini/GMOS- II: Oxygen abundance gradients
In this paper we derived oxygen abundance gradients from HII regions located
in eleven galaxies in eight systems of close pairs. Long-slit spectra in the
range 4400-7300A were obtained with the Gemini Multi-Object Spec- trograph at
Gemini South (GMOS). Spatial profiles of oxygen abundance in the gaseous phase
along galaxy disks were obtained using calibrations based on strong
emission-lines (N2 and O3N2). We found oxygen gradients signifi- cantly flatter
for all the studied galaxies than those in typical isolated spiral galaxies.
Four objects in our sample, AM1219A, AM1256B, AM 2030A and AM2030B, show a
clear break in the oxygen abundance at galactocentric radius R/R25 between 0.2
and 0.5. For AM1219A and AM1256B we found negative slopes for the inner
gradients, and for AM2030B we found a positive one. In all these three cases
they show a flatter behaviour to the outskirts of the galaxies. For AM2030A, we
found a positive-slope outer gradient while the inner one is almost compatible
with a flat behaviour. A decrease of star forma- tion efficiency in the zone
that corresponds to the oxygen abundance gradient break for AM1219A and AM2030B
was found. For the former, a minimum in the estimated metallicities was found
very close to the break zone that could be associated with a corotation radius.
On the other hand, AM1256B and AM2030A, present a SFR maximum but not an
extreme oxygen abundance value. All the four interacting systems that show
oxygen gradient breakes the extreme SFR values are located very close to break
zones. Hii regions lo- cated in close pairs of galaxies follow the same
relation between the ionization parameter and the oxygen abundance as those
regions in isolated galaxies.Comment: 30 pages, 14 figures, accepted MNRAS, (Figs. 1 and 2 are in low
resolution
Rat pial microvascular responses to melatonin during bilateral common carotid artery occlusion and reperfusion
The present study assessed the in vivo rat pial microvascular responses induced by melatonin during brain hypoperfusion and reperfusion (RE) injury. Pial microcirculation of male Wistar rats was visualized by fluorescence microscopy through a closed cranial window. Hypoperfusion was induced by bilateral common carotid artery occlusion (BCCAO, 30 min); thereafter, pial microcirculation was observed for 60 min. Arteriolar diameter, permeability increase, leukocyte adhesion to venular walls, perfused capillary length (PCL), and capillary red blood cell velocity (V(RBC) ) were investigated by computerized methods. Melatonin (0.5, 1, 2 mg/kg b.w.) was intravenously administered 10 min before BCCAO and at the beginning of RE. Pial arterioles were classified in five orders according to diameter, length, and branchings. In control group, BCCAO caused decrease in order 2 arteriole diameter (by 17.5 ± 3.0% of baseline) that was reduced by 11.8 ± 1.2% of baseline at the end of RE, accompanied by marked leakage and leukocyte adhesion. PCL and capillary V(RBC) decreased. At the end of BCCAO, melatonin highest dosage caused order 2 arteriole diameter reduction by 4.6 ± 2.0% of baseline. At RE, melatonin at the lower dosages caused different arteriolar responses. The highest dosage caused dilation in order 2 arteriole by 8.0 ± 1.5% of baseline, preventing leakage and leukocyte adhesion, while PCL and V(RBC) increased. Luzindole (4 mg/kg b.w.) prior to melatonin caused order 2 arteriole constriction by 12.0 ± 1.5% of baseline at RE, while leakage, leukocyte adhesion, PCL and V(RBC) were not affected. Prazosin (1 mg/kg b.w.) prior to melatonin did not significantly change melatonin's effects. In conclusion, melatonin caused different responses during hypoperfusion and RE, modulating pial arteriolar tone likely by MT1 and MT2 melatonin receptors while preventing blood-brain barrier changes through its free radical scavenging action
Do mental health and vitality mediate the relationship between perceived control over time and fear of COVID-19? A survey in an Italian sample
Several studies evidenced increased elevated symptomatology levels in anxiety, general stress, depression, and post-traumatic stress related to COVID-19. Real difficulties in the effective control of time that could be responsible for mental health issues and loss of vitality were also reported. Prior literature highlighted how perceived control over time significantly modulates anxiety disorders and promotes psychological well-being. To verify the hypothesis that perceived control over time predicts fear of COVID-19 and mental health and vitality mediate this relationship, we performed an online survey on a sample of 301 subjects (female = 68%; Mage = 22.12, SD = 6.29; age range = 18–57 years), testing a parallel mediation model using PROCESS macro (model 4). All participants responded to self-report measures of perceived control over time, COVID-19 fear, mental health, and vitality subscales of the Short-Form-36 Health Survey. Results corroborate the hypotheses of direct relationships between all the study variables and partially validate the mediation’s indirect effect. Indeed, mental health (a1b1 = −0.06; CI: LL = −0.11; UL = −0.01; p < 0.001) rather than vitality (a2b2 = −0.06; CI: LL = −0.09; UL = 0.03; n.s.) emerges as a significant mediator between perceived control over time and fear of COVID-19. Practical implications of the study about treatment programs based on perceived control over time and emotional coping to prevent fear and anxiety toward the COVID-19 pandemic are discussed
Optical and mid-infrared neon abundance determinations in star-forming regions
We employed observational spectroscopic data of star-forming regions compiled
from the literature and photoionization models to analyse the neon ionic
abundances obtained using both optical and mid-infrared emission-lines.
Comparing Ne++/H+ ionic abundances from distinct methods, we found that, in
average, the abundances obtained via IR emission-lines are higher than those
obtained via optical lines by a factor of 4. Photoionization models with
abundance variations along the radius of the hypothetical nebula provide a
possible explanation for a large part of the difference between ionic
abundances via optical and infrared emission-lines. Ionization Correction
Factor (ICF) for the neon is obtained from direct determinations of ionic
fractions using infrared emission-lines. A constant Ne/O ratio (logNe/O \approx
-0.70) for a large range of metallicity, independently of the ICF used to
compute the neon total abundance is derived.Comment: 17 pages, 14 figures, accepted by MNRA
Rapid onset of bronchodilation with formoterol/beclomethasone Modulite and formoterol/budesonide Turbuhaler as compared to formoterol alone in patients with COPD
In the present study, we examined whether there is a difference in the onset of bronchodilatation between formoterol/beclomethasone 12/200 μg Modulite and formoterol/budesonide 9/320 μg Turbuhaler in patients with COPD. We enrolled 28 patients with stable COPD. Both formoterol/beclomethasone and formoterol/budesonide elicited a larger mean FEV1–AUC0−15min than formoterol alone, whereas there was no significant difference between their FEV1–AUC0−15min. Also the change in FEV1 15 min after inhalation of formoterol/beclomethasone combination or formoterol/budesonide combination was greater than that induced by formoterol alone. This study confirms the rapid effect of the inhaled corticosteroid component when combined with formoterol and indicates that the onset of bronchodilation of formoterol/beclomethasone Modulite and formoterol/budesonide Turbuhaler are similar and greater than formoterol alone in patients with COPD
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