430 research outputs found
Light vector meson production at forward rapidity in pp collisions at √s = 5.02 TeV with ALICE
Among the four fundamental forces, three of them occur at low scale. These three
forces are all described in the so-called Standard Model of particles. Among them the
force keeping the protons and neutrons bound together, the strong force, is of special
interest in this presentation. This force is described by the Quantum Chromo-Dynamics
(QCD) theory. Hadrons, such as protons and neutrons, are composed of gluons and
quarks. Quarks are kept bound, at least by pairs by the strong force mediated via the
gluons and cannot be dissociated.
Only in the case of a high energy density (equivalent to high temperature) or at high
baryon chemical potential, quarks and gluons can propagate freely, forming a Quark
Gluon Plasma (QGP). This state is expected to have existed during the first micro-
seconds of the Universe.
These extreme conditions can actually be reproduced using heavy-ion collisions at the
Large Hadron Collider (LHC). The QGP is expected to be created in the most central heavy ion collisions such as in Pb-Pb collisions at = 5.02~TeV. Used as a reference, pp collisions where the QGP is not expected to be created are also performed. The QGP can be studied, and its equation of state evaluated investigating the particle yields resulting from these collisions.
Different probes of existence of the QGP are studied, in this thesis we investigate the low mass vector mesons with the dimuon decay channel at low mass (2~GeV/) measured in A Large Ion Collider Experiment (ALICE). Only interacting electroweakly within the medium, the dimuon decay channel is considered as a clean probe and allows the reconstruction of various mesons among which the and the meson. Due to its content, the meson has the particularity of having strange content, but a null net strangeness content. For this reason, the meson is a particular probe to study the so-called strangeness enhancement, an effect proposed as a signature of the QGP. However, the meson is composed of light flavour quarks and can be used as a reference for a strange hadron production.
Recently observed in small collision systems (such as pp), the strangeness enhancement is benefiting of a regain of interest. In this thesis the results on the and mesons production in pp collision at 5.02~TeV at forward rapidity with ALICE is presented. This thesis present the production of these mesons as a function of their transverse momentum, rapidity and multiplicity and the comparison to various model predictions
Online Calibration of the TPC Drift Time in the ALICE High Level Trigger
ALICE (A Large Ion Collider Experiment) is one of four major experiments at
the Large Hadron Collider (LHC) at CERN. The High Level Trigger (HLT) is a
compute cluster, which reconstructs collisions as recorded by the ALICE
detector in real-time. It employs a custom online data-transport framework to
distribute data and workload among the compute nodes.
ALICE employs subdetectors sensitive to environmental conditions such as
pressure and temperature, e.g. the Time Projection Chamber (TPC). A precise
reconstruction of particle trajectories requires the calibration of these
detectors. Performing the calibration in real time in the HLT improves the
online reconstructions and renders certain offline calibration steps obsolete
speeding up offline physics analysis. For LHC Run 3, starting in 2020 when data
reduction will rely on reconstructed data, online calibration becomes a
necessity. Reconstructed particle trajectories build the basis for the
calibration making a fast online-tracking mandatory. The main detectors used
for this purpose are the TPC and ITS (Inner Tracking System). Reconstructing
the trajectories in the TPC is the most compute-intense step.
We present several improvements to the ALICE High Level Trigger developed to
facilitate online calibration. The main new development for online calibration
is a wrapper that can run ALICE offline analysis and calibration tasks inside
the HLT. On top of that, we have added asynchronous processing capabilities to
support long-running calibration tasks in the HLT framework, which runs
event-synchronously otherwise. In order to improve the resiliency, an isolated
process performs the asynchronous operations such that even a fatal error does
not disturb data taking. We have complemented the original loop-free HLT chain
with ZeroMQ data-transfer components. [...]Comment: 8 pages, 10 figures, proceedings to 2016 IEEE-NPSS Real Time
Conferenc
Les perspectives des étudiants et des professeurs sur l’excellence dans l’utilisation des TIC et du cyberapprentissage au collégial
"Ce document est basé sur le rapport final d’un projet financé par le Fonds de recherche du Québec – Société et culture (FRQSC) et son partenaire, le ministère de l’Éducation et de l’Enseignement Supérieur (MEES) dans le cadre du programme Actions concertées Persévérance et réussite scolaires."Comprend un résumé, des références bibliographiques et des annexe
Student and professor perspectives on exemplary practices in the use of information and communication technologies (ICTs) and e-learning in colleges
"This document is based on the final report of a projet funded by the Fonds de recherche du Québec – Société et culture (FRQSC) and its partner the ministère de l’Éducation et de l’Enseignement supérieur (MEES) for the program Actions concertées Persévérance et réussite scolaires."Comprend un résumé, des références bibliographiques et des annexe
Culture shapes how we look at faces
Background: Face processing, amongst many basic visual skills, is thought to be invariant across all humans. From as early as 1965, studies of eye movements have consistently revealed a systematic triangular sequence of fixations over the eyes and the mouth, suggesting that faces elicit a universal, biologically-determined information extraction pattern. Methodology/Principal Findings: Here we monitored the eye movements of Western Caucasian and East Asian observers while they learned, recognized, and categorized by race Western Caucasian and East Asian faces. Western Caucasian observers reproduced a scattered triangular pattern of fixations for faces of both races and across tasks. Contrary to intuition, East Asian observers focused more on the central region of the face. Conclusions/Significance: These results demonstrate that face processing can no longer be considered as arising from a universal series of perceptual events. The strategy employed to extract visual information from faces differs across cultures
Connectome-wide Mega-analysis Reveals Robust Patterns of Atypical Functional Connectivity in Autism
Background
Neuroimaging studies of functional connectivity (FC) in autism have been hampered by small sample sizes and inconsistent findings with regard to whether connectivity is increased or decreased in individuals with autism, whether these alterations affect focal systems or reflect a brain-wide pattern, and whether these are age and/or sex dependent.
Methods
The study included resting-state functional magnetic resonance imaging and clinical data from the EU-AIMS LEAP (European Autism Interventions Longitudinal European Autism Project) and the ABIDE (Autism Brain Imaging Data Exchange) 1 and 2 initiatives of 1824 (796 with autism) participants with an age range of 5–58 years. Between-group differences in FC were assessed, and associations between FC and clinical symptom ratings were investigated through canonical correlation analysis.
Results
Autism was associated with a brainwide pattern of hypo- and hyperconnectivity. Hypoconnectivity predominantly affected sensory and higher-order attentional networks and correlated with social impairments, restrictive and repetitive behavior, and sensory processing. Hyperconnectivity was observed primarily between the default mode network and the rest of the brain and between cortical and subcortical systems. This pattern was strongly associated with social impairments and sensory processing. Interactions between diagnosis and age or sex were not statistically significant.
Conclusions
The FC alterations observed, which primarily involve hypoconnectivity of primary sensory and attention networks and hyperconnectivity of the default mode network and subcortex with the rest of the brain, do not appear to be age or sex dependent and correlate with clinical dimensions of social difficulties, restrictive and repetitive behaviors, and alterations in sensory processing. These findings suggest that the observed connectivity alterations are stable, trait-like features of autism that are related to the main symptom domains of the condition
Les deux côtés de la médaille : la perception des élèves de l'usage que font leurs enseignantes et enseignants des technologies de l'information et de la communication (TIC)
Affiche présentée dans le cadre du Colloque de l'ARC, «La relève scientifique et la recherche collégiale : pratiques inspirantes au regard des chercheuses et chercheurs, et enjeux spécifiques à la formation des étudiantes et étudiants», dans le cadre du 84e Congrès de l'Acfas, Université du Québec à Montréal, Montréal, le 10 mai 2016.Le Réseau de recherche ADAPTECH a étudié la fréquence d’utilisation de divers outils technologiques en classe par des élèves de cégep, d’une part, et par des enseignantes et enseignants réputés auprès des élèves pour leur excellente utilisation de la technologie, d’autre part. Dans cette recherche, il s’est également demandé quels étaient les outils favorisant le mieux la réussite des élèves. Son objectif était d’examiner l’expérience des élèves avec les TIC au collégial, et de comprendre en quoi celle-ci se distingue de celle du personnel enseignant. Le terme TIC recouvrait une grande variété d’outils : tableaux blancs interactifs, télécommandes, système de gestion de cours, vidéoconférences, etc. L’étude explique comment on pourrait mieux utiliser les TIC en classe, car elle intègre les points de vue des élèves et ceux du personnel enseignant. Les similitudes et différences entre les deux groupes ont été analysées par un sondage en ligne auprès d’élèves (n = 311) et des entrevues semi-structurées auprès d’enseignantes et d’enseignants choisis par leurs élèves pour leur excellente utilisation des TIC (n = 114). Une des grandes différences est qu’un fort pourcentage des élèves aime les cours où ils utilisent leurs propres outils technologiques, alors qu’un faible pourcentage du personnel enseignant leur permet de le faire
Reading between Eye Saccades
Background: Skilled adult readers, in contrast to beginners, show no or little increase in reading latencies as a function of the number of letters in words up to seven letters. The information extraction strategy underlying such efficiency in word identification is still largely unknown, and methods that allow tracking of the letter information extraction through time between eye saccades are needed to fully address this question. Methodology/Principal Findings: The present study examined the use of letter information during reading, by means of the Bubbles technique. Ten participants each read 5,000 five-letter French words sampled in space-time within a 200 ms window. On the temporal dimension, our results show that two moments are especially important during the information extraction process. On the spatial dimension, we found a bias for the upper half of words. We also show for the first time that letter positions four, one, and three are particularly important for the identification of five-letter words. Conclusions/Significance: Our findings are consistent with either a partially parallel reading strategy or an optimal serial reading strategy. We show using computer simulations that this serial reading strategy predicts an absence of a wordlength effect for words from four- to seven letters in length. We believe that the Bubbles technique will play an importan
Ground-breaking Exoplanet Science with the ANDES spectrograph at the ELT
In the past decade the study of exoplanet atmospheres at high-spectral
resolution, via transmission/emission spectroscopy and cross-correlation
techniques for atomic/molecular mapping, has become a powerful and consolidated
methodology. The current limitation is the signal-to-noise ratio during a
planetary transit. This limitation will be overcome by ANDES, an optical and
near-infrared high-resolution spectrograph for the ELT. ANDES will be a
powerful transformational instrument for exoplanet science. It will enable the
study of giant planet atmospheres, allowing not only an exquisite determination
of atmospheric composition, but also the study of isotopic compositions,
dynamics and weather patterns, mapping the planetary atmospheres and probing
atmospheric formation and evolution models. The unprecedented angular
resolution of ANDES, will also allow us to explore the initial conditions in
which planets form in proto-planetary disks. The main science case of ANDES,
however, is the study of small, rocky exoplanet atmospheres, including the
potential for biomarker detections, and the ability to reach this science case
is driving its instrumental design. Here we discuss our simulations and the
observing strategies to achieve this specific science goal. Since ANDES will be
operational at the same time as NASA's JWST and ESA's ARIEL missions, it will
provide enormous synergies in the characterization of planetary atmospheres at
high and low spectral resolution. Moreover, ANDES will be able to probe for the
first time the atmospheres of several giant and small planets in reflected
light. In particular, we show how ANDES will be able to unlock the reflected
light atmospheric signal of a golden sample of nearby non-transiting habitable
zone earth-sized planets within a few tenths of nights, a scientific objective
that no other currently approved astronomical facility will be able to reach.Comment: 66 pages (103 with references) 20 figures. Submitted to Experimental
Astronom
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