The first evidence of spin alignment of vector mesons ( K*0 and ϕ ) in heavy-ion collisions at the Large Hadron Collider (LHC) is reported. The spin density matrix element ρ 00 is measured at ...midrapidity ( | y | < 0.5 ) in Pb-Pb collisions at a center-of-mass energy ( √sNN ) of 2.76 TeV with the ALICE detector. ρ 00 values are found to be less than 1/3 (1/3 implies no spin alignment) at low transverse momentum ( p T < 2 GeV / c ) for K*0 and ϕ at a level of 3 σ and 2 σ , respectively. No significant spin alignment is observed for the K0S meson ( spin = 0 ) in Pb-Pb collisions and for the vector mesons in p p collisions. The measured spin alignment is unexpectedly large but qualitatively consistent with the expectation from models which attribute it to a polarization of quarks in the presence of angular momentum in heavy-ion collisions and a subsequent hadronization by the process of recombination.
The Alpha Magnetic Spectrometer (AMS) is a precision particle physics detector on the International Space Station (ISS) conducting a unique, long-duration mission of fundamental physics research in ...space. The physics objectives include the precise studies of the origin of dark matter, antimatter, and cosmic rays as well as the exploration of new phenomena. Following a 16-year period of construction and testing, and a precursor flight on the Space Shuttle, AMS was installed on the ISS on May 19, 2011. In this report we present results based on 120 billion charged cosmic ray events up to multi-TeV energies. This includes the fluxes of positrons, electrons, antiprotons, protons, and nuclei. These results provide unexpected information, which cannot be explained by the current theoretical models. The accuracy and characteristics of the data, simultaneously from many different types of cosmic rays, provide unique input to the understanding of origins, acceleration, and propagation of cosmic rays.
Abstract
Fragility fractures represent a growing global problem, including in the United Kingdom and European countries. Reports demonstrate the benefits of national guidance and organized fragility ...fracture programs through fracture liaison services to deliver care to patients who sustain these injuries. The challenge of assembling multidisciplinary teams, providing routine screening of appropriate patients, and monitoring therapies where there is a known compliance problem, remains an obstacle to the success of fragility fracture treatment programs to all. Efforts should continue to introduce and maintain fracture liaison services through coordinated national approaches and advanced systems.
The world was not prepared for the global of pandemic in early 2020 with the arrival of COVID 19. Europe has some of the most developed health care systems in the world and this article explains the ...initial response to the pandemic from an orthopaedic and trauma viewpoint from 8 nations. Italy reported the first cluster in February, which then rapidly spread around the continent, requiring a rapid reorganization of services. The reports highlight how elective surgery was universally stopped, surgical services were reconfigured, and new practices, such as the widespread use of telemedicine, may well become permanent. It also emphasizes how the pandemic has re-educated us on the importance of a consistent and central approach to deal with a global health crisis, and how medical services need to remain flexible and responsive to new ways of working.
Measurements of anisotropic flow coefficients (vn) and their cross-correlations using two- and multiparticle cumulant methods are reported in collisions of pp at s=13 TeV, p−Pb at a center-of-mass ...energy per nucleon pair sNN=5.02 TeV, Xe-Xe at sNN=5.44 TeV, and Pb-Pb at sNN=5.02 TeV recorded with the ALICE detector. The multiplicity dependence of vn is studied in a very wide range from 20 to 3000 particles produced in the midrapidity region |η|<0.8 for the transverse momentum range 0.2<pT<3.0 GeV/c. An ordering of the coefficients v2>v3>v4 is found in pp and p−Pb collisions, similar to that seen in large collision systems, while a weak v2 multiplicity dependence is observed relative to nucleus-nucleus collisions in the same multiplicity range. Using a novel subevent method, v2 measured with four-particle cumulants is found to be compatible with that from six-particle cumulants in pp and p−Pb collisions. The magnitude of the correlation between vn2 and vm2, evaluated with the symmetric cumulants SC(m,n) is observed to be positive at all multiplicities for v2 and v4, while for v2 and v3 it is negative and changes sign for multiplicities below 100, which may indicate a different vn fluctuation pattern in this multiplicity range. The observed long-range multiparticle azimuthal correlations in high multiplicity pp and p−Pb collisions can neither be described by pythia 8 nor by impact-parameter-Glasma, music, and ultrarelativistic quantum molecular dynamics model calculations, and hence, provide new insights into the understanding of collective effects in small collision systems.
A
bstract
We report the measured transverse momentum (
p
T
) spectra of primary charged particles from pp, p-Pb and Pb-Pb collisions at a center-of-mass energy
s
N
N
=
5.02
TeV in the kinematic range ...of 0
.
15
< p
T
<
50 GeV/
c
and |
η
|
<
0
.
8. A significant improvement of systematic uncertainties motivated the reanalysis of data in pp and Pb-Pb collisions at
s
N
N
=
2.76
TeV, as well as in p-Pb collisions at
s
N
N
=
5.02
TeV, which is also presented. Spectra from Pb-Pb collisions are presented in nine centrality intervals and are compared to a reference spectrum from pp collisions scaled by the number of binary nucleon-nucleon collisions. For central collisions, the
p
T
spectra are suppressed by more than a factor of 7 around 6–7 GeV/
c
with a significant reduction in suppression towards higher momenta up to 30 GeV/
c
. The nuclear modification factor
R
pPb
, constructed from the pp and p-Pb spectra measured at the same collision energy, is consistent with unity above 8 GeV/
c
. While the spectra in both pp and Pb-Pb collisions are substantially harder at
s
N
N
=
5.02
TeV compared to 2.76 TeV, the nuclear modification factors show no significant collision energy dependence. The obtained results should provide further constraints on the parton energy loss calculations to determine the transport properties of the hot and dense QCD matter.
The production cross sections for prompt charmed mesons
D
0
,
D
+
,
D
∗
+
and
D
s
+
were measured at mid-rapidity in proton–proton collisions at a centre-of-mass energy
s
=
7
TeV
with the ALICE ...detector at the Large Hadron Collider (LHC). D mesons were reconstructed from their decays
D
0
→
K
-
π
+
,
D
+
→
K
-
π
+
π
+
,
D
∗
+
→
D
0
π
+
,
D
s
+
→
ϕ
π
+
→
K
-
K
+
π
+
, and their charge conjugates.With respect to previous measurements in the same rapidity region, the coverage in transverse momentum (
p
T
) is extended and the uncertainties are reduced by a factor of about two. The accuracy on the estimated total
c
c
¯
production cross section is likewise improved. The measured
p
T
-differential cross sections are compared with the results of three perturbative QCD calculations.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The first measurement at the LHC of charge-dependent directed flow (v1) relative to the spectator plane is presented for Pb-Pb collisions at √ s NN = 5.02 TeV . Results are reported for charged ...hadrons and D 0 mesons for the transverse momentum intervals p T > 0.2 GeV / c and 3 < p T < 6 GeV / c in the 5%–40% and 10%–40% centrality classes, respectively. The difference between the positively and negatively charged hadron v 1 has a positive slope as a function of pseudorapidity η , dΔv1/dη = 1.68 ± 0.49 ( stat ) ± 0.41 ( syst ) × 10−4 . The same measurement for D0 and ¯ D0 mesons yields a positive value d Δv1/dη = 4.9 ± 1.7 ( stat ) ± 0.6 ( syst ) × 10−1, which is about 3 orders of magnitude larger than the one of the charged hadrons. These measurements can provide new insights into the effects of the strong electromagnetic field and the initial tilt of matter created in noncentral heavy ion collisions on the dynamics of light (u, d, and s) and heavy (c) quarks. The large difference between the observed Δv1 of charged hadrons and D0 mesons may reflect different sensitivity of the charm and light quarks to the early time dynamics of a heavy ion collision. These observations challenge some recent theoretical calculations, which predicted a negative and an order of magnitude smaller value of d Δv1/dη for both light flavor and charmed hadrons.
Background With the increase in life expectancy worldwide, changes in stroke subtypes and burden of stroke population are expected in both developing and developed countries. Prevalence of stroke ...subtypes and comorbidity in ischemic stroke patients was assessed in Brasilia, Brazil, and Cuenca, Spain. Methods This was an international (Brazilian-Spanish) cross-sectional study. Stroke subtypes were assessed by means of Trial of ORG 10172 in Acute Stroke Treatment (TOAST) classification. Modified Rankin scale was used to measure functional recovery and the Cumulative Illness Rating Scale for Geriatrics (CIRS-G) was used to assess comorbidity. Results A total of 500 patients (mean age 66.2 ± 16.4 years; 48% female; 48.2% Spanish) were included in the study. Spanish patients were significantly older than Brazilian ones (76.4 ± 11.2 versus 56.7 ± 14.6 years; P < .0001). Prevalence of ischemic cardiopathy (20.3% versus 6.2%) and atrial fibrillation (25.7% versus 6.6%) was significantly higher in Spanish stroke patients, whereas they less frequently used tobacco (28.3% versus 52.9%); P less than .0001. Prevalence of stroke subtypes in Spanish and Brazilian stroke patients was: stroke of undetermined etiology (58.1% versus 32.4%), cardioembolism (24.5% versus 11.6%), lacunar infarct (11.6% versus 25.5%), atherothrombotic (3.7% versus 19.7%), and other causes (2.1% versus 10.8%); P less than .0001. The Spanish sample had a significantly higher frequency of comorbidities. The CIRS-G total score and CIRS-G mean number of affected organs significantly increased with age, and correlated with the level of functional dependence as measured by Rankin scale (rS = 0.50; P = .0005). Conclusion Spanish stroke people had a higher frequency of comorbid conditions, atrial fibrillation, and cardioembolism and these facts were associated with age. Atherothrombotic and lacunar strokes were more common in the younger Brazilian stroke population.
The study of the strength and behavior of the antikaon-nucleon (Kover ¯N) interaction constitutes one of the key focuses of the strangeness sector in low-energy quantum chromodynamics (QCD). In this ...Letter a unique high-precision measurement of the strong interaction between kaons and protons, close and above the kinematic threshold, is presented. The femtoscopic measurements of the correlation function at low pair-frame relative momentum of (K^{+}p⊕K^{-}pover ¯) and (K^{-}p⊕K^{+}pover ¯) pairs measured in pp collisions at sqrts=5, 7, and 13 TeV are reported. A structure observed around a relative momentum of 58 MeV/c in the measured correlation function of (K^{-}p⊕K^{+}pover ¯) with a significance of 4.4σ constitutes the first experimental evidence for the opening of the (Kover ¯^{0}n⊕K^{0}nover ¯) isospin breaking channel due to the mass difference between charged and neutral kaons. The measured correlation functions have been compared to Jülich and Kyoto models in addition to the Coulomb potential. The high-precision data at low relative momenta presented in this work prove femtoscopy to be a powerful complementary tool to scattering experiments and provide new constraints above the Kover ¯N threshold for low-energy QCD chiral models.
PDF
