2,217 research outputs found
Nonconventional use of flash-lamp pulsed-dye laser in dermatology
Flash-lamp pulsed-dye laser (FPDL) is a nonablative technology, typically used in vascular malformation therapy due to its specificity for hemoglobin. FPDL treatments were performed in a large group of patients with persistent and/or recalcitrant different dermatological lesions with cutaneous microvessel involvement. In particular, 149 patients (73 males and 76 females) were treated. They were affected by the following dermatological disorders: angiokeratoma circumscriptum, genital and extragenital viral warts, striae rubrae, basal cell carcinoma, Kaposi's sarcoma, angiolymphoid hyperplasia, and Jessner-Kanof disease. They all underwent various laser sessions. 89 patients (59.7%) achieved excellent clearance, 32 patients (21.4%) achieved good-moderate clearance, 19 patients (12.7%) obtained slight clearance, and 9 subjects (6.1%) had low or no removal of their lesion. In all cases, FPDL was found to be a safe and effective treatment for the abovementioned dermatological lesions in which skin microvessels play a role in pathogenesis or development. Further and single-indication studies, however, are required to assess a standardized and reproducible method for applying this technology to "off-label" indications
Spectral morphological analysis of skin lesions with a polarization multispectral dermoscope.
Dermoscopy is the conventional technique used for the clinical inspection of human skin lesions. However, the identification of diagnostically relevant morphologies can become a complex task. We report on the development of a polarization multispectral dermoscope for the in vivo imaging of skin lesions. Linearly polarized illumination at three distinct spectral regions (470, 530 and 625 nm), is performed by high luminance LEDs. Processing of the acquired images, by means of spectral and polarization filtering, produces new contrast images, each one specific for melanin absorption, hemoglobin absorption, and single scattering. Analysis of such images could facilitate the identification of pathological morphologies. (C) 2013 Optical Society of Americ
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
Search for chargino-neutralino production with mass splittings near the electroweak scale in three-lepton final states in √s=13 TeV pp collisions with the ATLAS detector
A search for supersymmetry through the pair production of electroweakinos with mass splittings near the electroweak scale and decaying via on-shell W and Z bosons is presented for a three-lepton final state. The analyzed proton-proton collision data taken at a center-of-mass energy of √s=13 TeV were collected between 2015 and 2018 by the ATLAS experiment at the Large Hadron Collider, corresponding to an integrated luminosity of 139 fb−1. A search, emulating the recursive jigsaw reconstruction technique with easily reproducible laboratory-frame variables, is performed. The two excesses observed in the 2015–2016 data recursive jigsaw analysis in the low-mass three-lepton phase space are reproduced. Results with the full data set are in agreement with the Standard Model expectations. They are interpreted to set exclusion limits at the 95% confidence level on simplified models of chargino-neutralino pair production for masses up to 345 GeV
Search for direct stau production in events with two hadronic tau-leptons in root s=13 TeV pp collisions with the ATLAS detector
A search for the direct production of the supersymmetric partners ofτ-leptons (staus) in final stateswith two hadronically decayingτ-leptons is presented. The analysis uses a dataset of pp collisions corresponding to an integrated luminosity of139fb−1, recorded with the ATLAS detector at the LargeHadron Collider at a center-of-mass energy of 13 TeV. No significant deviation from the expected StandardModel background is observed. Limits are derived in scenarios of direct production of stau pairs with eachstau decaying into the stable lightest neutralino and oneτ-lepton in simplified models where the two staumass eigenstates are degenerate. Stau masses from 120 GeV to 390 GeV are excluded at 95% confidencelevel for a massless lightest neutralino
Measurement of the nuclear modification factor of b-jets in 5.02 TeV Pb+Pb collisions with the ATLAS detector
This paper presents a measurement of b-jet production in Pb+Pb and pp collisions at sqrt(s_NN)=5.02
TeV with the ATLAS detector at the LHC. The measurement uses 260 pb^{−1} of pp collisions collected in 2017 and 1.4 nb^{−1} of Pb+Pb collisions collected in 2018. In both collision systems, jets are reconstructed via the anti-kt algorithm. The b-jets are identified from a sample of jets containing muons from the semileptonic decay of b-quarks using template fits of the muon momentum relative to the jet axis. In pp collisions, b-jets are reconstructed for radius parameters R=0.2 and R=0.4, and only R=0.2 jets are used in Pb+Pb collisions. For comparison, inclusive R=0.2 jets are also measured using 1.7 nb^{−1} of Pb+Pb collisions collected in 2018 and the same pp collision data as the b-jet measurement. The nuclear modification factor, R_{AA}, is calculated for both b-jets and inclusive jets with R=0.2 over the transverse momentum range of 80-290 GeV. The nuclear modification factor for b-jets decreases from peripheral to central collisions. The ratio of the b-jet R_{AA} to inclusive jet R_{AA} is also presented and suggests that the R_{AA} for b-jets is larger than that for inclusive jets in central Pb+Pb collisions. The measurements are compared with theoretical calculations and suggest a role for mass and colour-charge effects in partonic energy loss in heavy-ion collisions
Measurement of muon pairs produced via γγ scattering in nonultraperipheral Pb+Pb collisions at sqrt(s_NN)=5.02 TeV with the ATLAS detector
Results of a measurement of dimuon photoproduction in nonultraperipheral Pb+Pb collisions at sqrt(s_NN)=5.02 TeV are presented. The measurement uses ATLAS data from the 2015 and 2018 Pb+Pb data-taking periods at the LHC with an integrated luminosity of
1.94 nb^{−1}. The γγ→μ+μ− pairs are identified via selections on pair momentum asymmetry and acoplanarity. Differential cross sections for dimuon production are measured in different centrality, average muon momentum, and pair rapidity intervals as functions of acoplanarity and k⊥, the transverse momentum kick of one muon relative to the other. Measurements are also made as a function of the rapidity separation of the muons and the angle of the muon pair relative to the second-order event plane to test whether magnetic fields generated in the quark-gluon plasma affect the measured muons. A prior observation of a centrality-dependent broadening of the acoplanarity distribution is confirmed. Furthermore, the improved precision of the measurement reveals a depletion in the number of pairs having small acoplanarity or k⊥ values in more central collisions. The acoplanarity distributions in a given centrality interval are observed to vary with the mean pT of the muons in the pair, but the k⊥ distributions do not. Comparisons with recent theoretical predictions are made. The predicted trends associated with effects of magnetic fields on the dimuons are not observed
Correlations between flow and transverse momentum in Xe+Xe and Pb+Pb collisions at the LHC with the ATLAS detector: A probe of the heavy-ion initial state and nuclear deformation
The correlations between flow harmonics v_n for n=2, 3, and 4 and mean transverse momentum [pT] in 129Xe+129Xe and 208Pb+208Pb collisions at sqrt(s)=5.44 and 5.02 TeV, respectively, are measured using charged particles with the ATLAS detector. The correlations are potentially sensitive to the shape and size of the initial geometry, nuclear deformation, and initial momentum anisotropy. The effects from nonflow and centrality fluctuations are minimized, respectively, via a subevent cumulant method and an event-activity selection based on particle production at very forward rapidity. The v_n−[pT] correlations show strong dependencies on centrality, harmonic number n, pT, and pseudorapidity range. Current models qualitatively describe the overall centrality- and system-dependent trends but fail to quantitatively reproduce all features of the data. In central collisions, where models generally show good agreement, the v_2−[pT] correlations are sensitive to the triaxiality of the quadruple deformation. Comparison of the model with the Pb+Pb and Xe+Xe
data confirms that the 129Xe nucleus is a highly deformed triaxial ellipsoid that has neither a prolate nor oblate shape. This provides strong evidence for a triaxial deformation of the 129Xe nucleus from high-energy heavy-ion collisions
Production of Υ(nS) mesons in Pb+Pb and pp collisions at 5.02 TeV
A measurement of the production of vector bottomonium states, Υ(1S), Y(2S), and Υ(3S), in Pb+Pb and pp collisions at a center-of-mass energy per nucleon pair of 5.02 TeV is presented. The data correspond to integrated luminosities of 1.38 nb^{−1} of Pb+Pb data collected in 2018, 0.44 nb^{−1} of Pb+Pb data collected in 2015, and 0.26 fb^{−1} of pp data collected in 2017 by the ATLAS detector at the Large Hadron Collider. The measurements are performed in the dimuon decay channel for transverse momentum p^{μμ}_T<30 GeV, absolute rapidity |y^{μμ}|<1.5, and Pb+Pb event centrality 0–80%. The production rates of the three bottomonium states in Pb+Pb collisions are compared with those in pp collisions to extract the nuclear modification factors as functions of event centrality, p^{μμ}_T, and |y^{μμ}|. In addition, the suppression of the excited states relative to the ground state is studied. The results are compared with theoretical model calculations
Measurements of the suppression and correlations of dijets in Pb+Pb collisions at sqrt(s_NN)=5.02 TeV
Studies of the correlations of the two highest transverse momentum (leading) jets in individual Pb+Pb collision events can provide information about the mechanism of jet quenching by the hot and dense matter created in such collisions. In Pb+Pb and pp collisions at sqrt(s_NN)=5.02 TeV, measurements of the leading dijet transverse momentum (pT) correlations are presented. Additionally, measurements in Pb+Pb collisions of the dijet pair nuclear modification factors projected along leading and subleading jet pT are made. The measurements are performed using the ATLAS detector at the LHC with 260 pb^{−1} of pp data collected in 2017 and 2.2 nb^{−1} of Pb+Pb data collected in 2015 and 2018. An unfolding procedure is applied to the two-dimensional leading and subleading jet pT distributions to account for experimental effects in the measurement of both jets. Results are provided for dijets with leading jet pT greater than 100 GeV. Measurements of the dijet-yield-normalized xJ distributions in Pb+Pb collisions show an increased fraction of imbalanced jets compared to pp collisions; these measurements are in agreement with previous measurements of the same quantity at 2.76 TeV in the overlapping kinematic range. Measurements of the absolutely normalized dijet rate in Pb+Pb and pp
collisions are also presented, and show that balanced dijets are significantly more suppressed than imbalanced dijets in Pb+Pb collisions. It is observed in the measurements of the pair nuclear modification factors that the subleading jets are significantly suppressed relative to leading jets with pT between 100 and 316 GeV for all centralities in Pb+Pb collisions
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