1,883 research outputs found
The Italian primary school-size distribution and the city-size: a complex nexus
We characterize the statistical law according to which Italian primary
school-size distributes. We find that the school-size can be approximated by a
log-normal distribution, with a fat lower tail that collects a large number of
very small schools. The upper tail of the school-size distribution decreases
exponentially and the growth rates are distributed with a Laplace PDF. These
distributions are similar to those observed for firms and are consistent with a
Bose-Einstein preferential attachment process. The body of the distribution
features a bimodal shape suggesting some source of heterogeneity in the school
organization that we uncover by an in-depth analysis of the relation between
schools-size and city-size. We propose a novel cluster methodology and a new
spatial interaction approach among schools which outline the variety of
policies implemented in Italy. Different regional policies are also discussed
shedding lights on the relation between policy and geographical features.Comment: 16 pages, 10 figure
Massive Neutrinos and the Higgs Mass Window
If neutrino masses are produced by a see-saw mechanism the Standard Model prediction for the Higgs mass window (defined by upper (perturbativity) and lower (stability) bounds) can be substantially affected. Actually the Higgs mass window can close completely, which settles an upper bound on the Majorana mass for the right-handed neutrinos, , ranging from GeV for three generations of quasi-degenerate massive neutrinos with eV, to GeV for just one relevant generation with eV. A slightly weaker upper bound on , coming from the requirement that the neutrino Yukawa couplings do not develop a Landau pole, is also discussed.If neutrino masses are produced by a see-saw mechanism the Standard Model prediction for the Higgs mass window (defined by upper (perturbativity) and lower (stability) bounds) can be substantially affected. Actually the Higgs mass window can close completely, which settles an upper bound on the Majorana mass for the right-handed neutrinos, , ranging from GeV for three generations of quasi-degenerate massive neutrinos with eV, to GeV for just one relevant generation with eV. A slightly weaker upper bound on , coming from the requirement that the neutrino Yukawa couplings do not develop a Landau pole, is also discussed
The Standard Model instability and the scale of new physics
We apply a general formalism for the improved effective potential with
several mass scales to compute the scale M of new physics which is needed to
stabilize the Standard Model potential in the presence of a light Higgs. We
find, by imposing perturbativity of the new physics, that M can be as large as
one order of magnitude higher than the instability scale of the Standard Model.
This implies that, with the present lower bounds on the Higgs mass, the new
physics could easily (but not necessarily) escape detection in the present and
future accelerators.Comment: latex2e, 12 pages, 3 figure
Ultraviolet Fixed Points in Gauge and SUSY Field Theories in Extra Dimensions
We consider gauge field theories in following the Wilson RG approach
and show that they possess the ultraviolet fixed points where the gauge
coupling is dimensionless in any space-time dimension. At the fixed point the
anomalous dimensions of the field and vertex operators are known exactly. These
fixed points are nonperturbative and correspond to conformal invariant
theories. The same phenomenon also happens in supersymmetric theories with the
Yukawa type interactions.Comment: LaTeX, 10pp. v2: Comments and references adde
Stroke subtypes and their possible implication in stroke prevention drug strategies
Thrombotic strokes can affect large or small arteries in the brain. Drugs to prevent atherosclerosis complication such as thrombotic strokes, should be drugs able to prevent the accumulation of intravascular fat, reduce vascular proliferation, decrease blood pressure levels with the resulting shear stress, reduce platelet aggregation, and possibly partially or totally reverse carotid plaques. Any of the commonly used antihypertensive drugs lower the incidence of stroke, with larger reductions in BP resulting in larger reductions in risk. Experimental and clinical data suggest that reducing the activity of the renin-angiotensin aldosterone system (RAAS) may have beneficial effects beyond the lowering of blood pressure to reduce stroke incidence. In clinical trials, statins consistently reduced the risk of ischemic stroke in patients with or without CHD whereas the data on the effects of other lipid modifying drugs on stroke risk are limited. Approximately 25% of strokes are recurrent. Antiplatelet therapy is indicated for the prevention of recurrent stroke in patients with a history of noncardioembolic minor stroke or transient ischemic attack (TIA). Although clinicians may choose acetylsalicylic acid (ASA) as first-line therapy for secondary prevention, clinical guidelines and evidence from trials suggest that ASA may not be the most effective strategy. A recent review discussed results from clinical trials that have compared the efficacy of ASA monotherapy versus ASA + extended release dipyridamole in secondary stroke prevention. Therefore it is difficult to extrapolate the real benefit of pharmacological prevention strategies against atherothrombotic subtype for excellence in the TOAST classification subtype that is represented by the LAAS and also with regard to lacunar subtype as an expression of lipohyalinosis process which is a further aspect of atherosclerosis
Supersymmetric Extra Dimensions: Gravitino Effects in Selectron Pair Production
We examine the phenomenological consequences of a supersymmetric bulk in the
scenario of large extra dimensions. We assume supersymmetry is realized in the
bulk and study the interactions of the resulting bulk gravitino Kaluza-Klein
(KK) tower of states, with supersymmetry breaking on the brane inducing a light
mass for the zero-mode gravitino. We derive the 4-d effective theory, including
the couplings of the bulk gravitino KK states to fermions and their scalar
superpartners. The virtual exchange of the gravitino KK states in selectron
pair production in polarized \epem collisions is then examined. We find that
the leading order operator for this exchange is dimension six, in contrast to
that of bulk graviton KK exchange which induces a dimension eight operator at
lowest order. The resulting kinematic distributions for selectron production
are dramatically altered from those in D=4 supersymmetric scenarios, and can
lead to a enormous sensitivity to the fundamental higher dimensional Planck
scale, of order .Comment: 48 pg
An Updated Review of Bioactive Peptides from Mushrooms in a Well-Defined Molecular Weight Range
Here, we report the current status of the bioactive peptides isolated and characterized from mushrooms during the last 20 years, considering ‘peptide’ a succession from to 2 to 100 amino acid residues. According to this accepted biochemical definition, we adopt ~10 kDa as the upper limit of molecular weight for a peptide. In light of this, a careful revision of data reported in the literature was carried out. The search revealed that in the works describing the characterization of bioactive peptides from mushrooms, not all the peptides have been correctly classified according to their molecular weight, considering that some fungal proteins (>10 kDa MW) have been improperly classified as ‘peptides’. Moreover, the biological action of each of these peptides, the principles of their isolation as well as the source/mushroom species were summarized. Finally, this review highlighted that these peptides possess antihypertensive, antifungal, antibiotic and antimicrobial, anticancer, antiviral, antioxidant and ACE inhibitory properties
Measurement of the cross-section and charge asymmetry of bosons produced in proton-proton collisions at TeV with the ATLAS detector
This paper presents measurements of the and cross-sections and the associated charge asymmetry as a
function of the absolute pseudorapidity of the decay muon. The data were
collected in proton--proton collisions at a centre-of-mass energy of 8 TeV with
the ATLAS experiment at the LHC and correspond to a total integrated luminosity
of 20.2~\mbox{fb^{-1}}. The precision of the cross-section measurements
varies between 0.8% to 1.5% as a function of the pseudorapidity, excluding the
1.9% uncertainty on the integrated luminosity. The charge asymmetry is measured
with an uncertainty between 0.002 and 0.003. The results are compared with
predictions based on next-to-next-to-leading-order calculations with various
parton distribution functions and have the sensitivity to discriminate between
them.Comment: 38 pages in total, author list starting page 22, 5 figures, 4 tables,
submitted to EPJC. All figures including auxiliary figures are available at
https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/STDM-2017-13
Performance of the CMS Cathode Strip Chambers with Cosmic Rays
The Cathode Strip Chambers (CSCs) constitute the primary muon tracking device
in the CMS endcaps. Their performance has been evaluated using data taken
during a cosmic ray run in fall 2008. Measured noise levels are low, with the
number of noisy channels well below 1%. Coordinate resolution was measured for
all types of chambers, and fall in the range 47 microns to 243 microns. The
efficiencies for local charged track triggers, for hit and for segments
reconstruction were measured, and are above 99%. The timing resolution per
layer is approximately 5 ns
Sodium valproate in migraine without aura and medication overuse headache: A randomized controlled trial
Objective: To assess the efficacy, safety and tolerability of sodium valproate (800. mg/die) compared with placebo in medication-overuse headache patients with a history of migraine without aura. Methods: This is a multicenter, randomized, double-blind, placebo-controlled study enrolled medication-overuse headache patients for a 3-month treatment period with sodium valproate (800. mg/day) or placebo after a 6 day outpatient detoxification regimen, followed by a 3-month follow-up. Primary outcome was defined by the proportion of patients achieving ≥50% reduction in the number of days with headache per month (responders) from the baseline to the last 4 weeks of the 3-month treatment. Multivariate logistic regression models were used on the primary endpoint, adjusting for age, sex, disease duration, comorbidity and surgery. The last-observation-carried-forward method was used to adjust for missing values. Results: Nine sites enrolled 130 patients and, after a 6-day detoxification phase, randomized 88 eligible patients. The 3-month responder rate was higher in the sodium valproate (45.0%) than in the placebo arm (23.8%) with an absolute difference of about 20% (p=0.0431). Sodium valproate had safety and tolerability profiles comparable to placebo. Conclusions: The present study supports the efficacy and safety of sodium valproate in the treatment of medication overuse headache with history of migraine after detoxification
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