302 research outputs found
Adaptable Pulse Compression in Ï-OTDR With Direct Digital Synthesis of Probe Waveforms and Rigorously Defined Nonlinear Chirping
Recent research in Phase-Sensitive Optical Time Doman Reflectometry (Ï-OTDR) has been focused, among others, on performing spatially resolved measurements with various methods including the use of frequency modulated probes. However, conventional schemes either rely on phase-coded sequences, involve inflexible generation of the probe frequency modulation or mostly employ simple linear frequency modulated (LFM) pulses which suffer from elevated sidelobes introducing degradation in range resolution. In this contribution, we propose and experimentally demonstrate a novel Ï-OTDR scheme which employs a readily adaptable Direct Digital Synthesis (DDS) of pulses with custom frequency modulation formats and demonstrate advanced optical pulse compression with a nonlinear frequency modulated (NLFM) waveform containing a complex, rigorously defined modulation law optimized for bandwidth-limited synthesis and sidelobe suppression. The proposed method offers high fidelity chirped waveforms, and when employed in resolving a 50-cm event at âŒ1.13 km using a 1.2-ÎŒs probe pulse, matched filtering with the DDS-generated NLFM waveform results in a significant reduction in range ambiguity owing to autocorrelation sidelobe suppression of âŒ20 dB with no averages and windowing functions, for an improvement of âŒ16 dB compared to conventional linear chirping. Experimental results also show that the contribution of autocorrelation sidelobes to the power in the compressed backscattering responses around localized events is suppressed by up to âŒ18 dB when advanced pulse compression with an optical NLFM pulse is employed
Complete revascularization with multivessel PCI for myocardial infarction
BACKGROUND
In patients with ST-segment elevation myocardial infarction (STEMI), percutaneous coronary intervention (PCI) of the culprit lesion reduces the risk of cardiovascular death or myocardial infarction. Whether PCI of nonculprit lesions further reduces the risk of such events is unclear.
METHODS
We randomly assigned patients with STEMI and multivessel coronary artery disease who had undergone successful culprit-lesion PCI to a strategy of either complete revascularization with PCI of angiographically significant nonculprit lesions or no further revascularization. Randomization was stratified according to the intended timing of nonculprit-lesion PCI (either during or after the index hospitalization). The first coprimary outcome was the composite of cardiovascular death or myocardial infarction; the second coprimary outcome was the composite of cardiovascular death, myocardial infarction, or ischemia-driven revascularization.
RESULTS
At a median follow-up of 3 years, the first coprimary outcome had occurred in 158 of the 2016 patients (7.8%) in the complete-revascularization group as compared with 213 of the 2025 patients (10.5%) in the culprit-lesion-only PCI group (hazard ratio, 0.74; 95% confidence interval [CI], 0.60 to 0.91; P=0.004). The second coprimary outcome had occurred in 179 patients (8.9%) in the complete-revascularization group as compared with 339 patients (16.7%) in the culprit-lesion-only PCI group (hazard ratio, 0.51; 95% CI, 0.43 to 0.61; P<0.001). For both coprimary outcomes, the benefit of complete revascularization was consistently observed regardless of the intended timing of nonculprit-lesion PCI (P=0.62 and P=0.27 for interaction for the first and second coprimary outcomes, respectively).
CONCLUSIONS
Among patients with STEMI and multivessel coronary artery disease, complete revascularization was superior to culprit-lesion-only PCI in reducing the risk of cardiovascular death or myocardial infarction, as well as the risk of cardiovascular death, myocardial infarction, or ischemia-driven revascularization. (Funded by the Canadian Institutes of Health Research and others; COMPLETE ClinicalTrials.gov number, NCT01740479. opens in new tab.
Spin alignment measurements using vector mesons with ALICE detector at the LHC
We present new measurements related to spin alignment of K*(0) vector
mesons at mid-rapidity for Pb-Pb collisions at root s(NN) = 2.76 and
5.02 TeV. The spin alignment measurements are carried out with respect
to production plane and 2nd order event plane. At low p(T) the spin
density matrix element rho(00) for K*(0) is found to have values
slightly below 1/3, while it is consistent with 1/3, i.e. no spin
alignment, at high p(T). Similar values of rho(00) are observed with
respect to both production plane and event plane. Within statistical and
systematic uncertainties, rho(00) values are also found to be
independent of root s(NN). rho(00) also shows centrality dependence with
maximum deviation from 1/3 for mid-central collisions with respect to
both the kinematic planes. The measurements for K*(0) in pp collisions
at root s = 13 TeV and for K-s(0) (a spin 0 hadron) in 20-40\% central
Pb-Pb collisions at root s(NN) = 2.76 TeV are consistent with no spin
alignment
Muon physics at forward rapidity with the ALICE detector upgrade
ALICE is the experiment specifically designed to study the Quark-Gluon
Plasma (QGP) in heavy-ion collisions at the CERN LHC. The ALICE detector
will be upgraded during the Long Shutdown 2, planned for 2019-2020, in
order to cope with the maximum interaction rate of 50 kHz of Pb-Pb
collisions foreseen for Runs 3 and 4. The ambitious programme of
high-precision measurements, expected for muon physics after 2020,
requires an upgrade of the front-end and readout electronics of the
existing Muon Spectrometer. This concerns the Cathode Pad Chambers (CPC)
used for tracking and the Resistive Plate Chambers (RPC) used for
triggering and for muon identification. The Muon Forward Tracker (MFT),
an internal tracker added in front of the front absorber of the existing
Muon Spectrometer, is also part of the ALICE detector upgrade programme.
It is based on an assembly of circular planes made of Monolithic Active
Pixel Sensors (MAPS), covering the pseudorapidity range 2.5 < eta < 3.6.
The MFT will improve present measurements and enable new ones. A
selection of results from physics performance studies will be presented,
together with an overview of the technical aspects of the upgrade
project
Direct photon elliptic flow in Pb-Pb collisions at root s(NN)=2.76 TeV
The elliptic flow of inclusive and direct photons was measured at mid-rapidity in two centrality classes 0-20% and 20-40% in Pb-Pb collisions at root s(NN) = 2.76 TeV by ALICE. Photons were detected with the highly segmented electromagnetic calorimeter PHOS and via conversions in the detector material with the e(broken vertical bar)e pairs reconstructed in the central tracking system. The results of the two methods were combined and the direct-photon elliptic flow was extracted in the transverse momentum range 0.9 < p(T) < 6.2 GeV/c. A comparison to RHIC data shows a similar magnitude of the measured direct-photon elliptic flow. Hydrodynamic and transport model calculations are systematically lower than the data, but are found to be compatible. (C) 2018 The Author. Published by Elsevier B.V.Peer reviewe
Higher moment fluctuations of identified particle distributions from ALICE
Cumulants of conserved charges fluctuations are regarded as a potential tool
to study the criticality in the QCD phase diagram and to determine the
freeze-out parameters in a model-independent way. At LHC energies, the
measurements of the ratio of the net-baryon (net-proton) cumulants can be used
to test the lattice QCD predictions. In this work, we present the first
measurements of cumulants of the net-proton number distributions up to
order in Pb--Pb collisions at = 2.76 and 5.02 TeV as a
function of collision centrality. We compare our cumulant ratios results with
the STAR experiment net-proton results measured in the first phase of the Beam
Energy Scan program at RHIC. The results can be used to obtain the chemical
freeze-out parameters at LHC.Comment: 4 pages, 3 figures, Proceedings of XXVIIth International Conference
on Ultrarelativistic Nucleus-Nucleus Collisions (Quark Matter 2018
Light (anti-)nuclei production and elliptic flow at the LHC with ALICE
Results on the production of stable light nuclei, including deuterons,
He-3, He-4 and the corresponding anti-nuclei, in Pb-Pb collisions at
root s(NN) = 2.76 TeV and root s(NN) = 5.02 TeV are presented and
compared with theoretical predictions and with the results in small
systems to provide insight into the production mechanisms of
(anti-)nuclei at colliders.
The experimental results are presented giving a critical view of their
comparison to the expectations from coalescence and hydrodynamic models
that aim at describing both the p(T)-spectra and the elliptic flow
Open heavy-flavour production and elliptic flow in p-Pb collisions at the LHC with ALICE
Measurements of open heavy flavour production in p-A collisions allow
the investigation of Cold Nuclear Matter effects. In addition, they are
an important tool for a complementary investigation of the long-range
correlations found in small systems in the light flavour sector. In this
work, production measurements of D mesons at mid-rapidity in p-Pb
collisions at root S-NN = 5.02 TeV are reported. Production yields are
also reported for the heavy-flavour hadron decay electrons at central
rapidity at root(SNN) = 5.02 and 8.16 TeV. The elliptic flow (nu(2)) of
heavy-flavour hadron decay electrons in high multiplicity p-Pb
collisions at root(SNN) = 5.02 TeV is found to be positive with a
significance larger than 5 sigma
Measuring (KSK +/-)-K-0 interactions using pp collisions at root s=7 TeV
We present the first measurements of femtoscopic correlations between the K-S(0) and K-+/- particles in pp collisions at root s = 7 TeV measured by the ALICE experiment. The observed femtoscopic correlations are consistent with final-state interactions proceeding solely via the a(0)(980) resonance. The extracted kaon source radius and correlation strength parameters for (KSK-)-K-0 are found to be equal within the experimental uncertainties to those for (KSK+)-K-0. Results of the present study are compared with those from identical-kaon femtoscopic studies also performed with pp collisions at root s = 7 TeV by ALICE and with a (KSK +/-)-K-0 measurement in Pb-Pb collisions at root s(NN) = 2.76 TeV. Combined with the Pb-Pb results, our pp analysis is found to be compatible with the interpretation of the a (980) having a tetraquark structure instead of that of a diquark. (C) 2018 Published by Elsevier B.V.Peer reviewe
Clinical features and outcomes of elderly hospitalised patients with chronic obstructive pulmonary disease, heart failure or both
Background and objective: Chronic obstructive pulmonary disease (COPD) and heart failure (HF) mutually increase the risk of being present in the same patient, especially if older. Whether or not this coexistence may be associated with a worse prognosis is debated. Therefore, employing data derived from the REPOSI register, we evaluated the clinical features and outcomes in a population of elderly patients admitted to internal medicine wards and having COPD, HF or COPDâ+âHF. Methods: We measured socio-demographic and anthropometric characteristics, severity and prevalence of comorbidities, clinical and laboratory features during hospitalization, mood disorders, functional independence, drug prescriptions and discharge destination. The primary study outcome was the risk of death. Results: We considered 2,343 elderly hospitalized patients (median age 81 years), of whom 1,154 (49%) had COPD, 813 (35%) HF, and 376 (16%) COPDâ+âHF. Patients with COPDâ+âHF had different characteristics than those with COPD or HF, such as a higher prevalence of previous hospitalizations, comorbidities (especially chronic kidney disease), higher respiratory rate at admission and number of prescribed drugs. Patients with COPDâ+âHF (hazard ratio HR 1.74, 95% confidence intervals CI 1.16-2.61) and patients with dementia (HR 1.75, 95% CI 1.06-2.90) had a higher risk of death at one year. The Kaplan-Meier curves showed a higher mortality risk in the group of patients with COPDâ+âHF for all causes (pâ=â0.010), respiratory causes (pâ=â0.006), cardiovascular causes (pâ=â0.046) and respiratory plus cardiovascular causes (pâ=â0.009). Conclusion: In this real-life cohort of hospitalized elderly patients, the coexistence of COPD and HF significantly worsened prognosis at one year. This finding may help to better define the care needs of this population
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