Suppression of charged particle production at large transverse momentum in central Pb-Pb collisions at sNN=2.76\sqrt{s_{\rm NN}} = 2.76 TeV

Inclusive transverse momentum spectra of primary charged particles in Pb-Pb collisions at $\sqrt{s_{_{\rm NN}}}$ = 2.76 TeV have been measured by the ALICE Collaboration at the LHC. The data are presented for central and peripheral collisions, corresponding to 0-5% and 70-80% of the hadronic Pb-Pb cross section. The measured charged particle spectra in $|\eta|<0.8$ and $0.3 < p_T < 20$ GeV/$c$ are compared to the expectation in pp collisions at the same $\sqrt{s_{\rm NN}}$, scaled by the number of underlying nucleon-nucleon collisions. The comparison is expressed in terms of the nuclear modification factor $R_{\rm AA}$. The result indicates only weak medium effects ($R_{\rm AA} \approx$ 0.7) in peripheral collisions. In central collisions, $R_{\rm AA}$ reaches a minimum of about 0.14 at $p_{\rm T}=6$-7GeV/$c$ and increases significantly at larger $p_{\rm T}$. The measured suppression of high-$p_{\rm T}$ particles is stronger than that observed at lower collision energies, indicating that a very dense medium is formed in central Pb-Pb collisions at the LHC.Comment: 15 pages, 5 captioned figures, 3 tables, authors from page 10, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/98

Two-pion Bose-Einstein correlations in central Pb-Pb collisions at sNN\sqrt{s_{\rm NN}} = 2.76 TeV

The first measurement of two-pion Bose-Einstein correlations in central Pb-Pb collisions at $\sqrt{s_{\rm NN}} = 2.76$ TeV at the Large Hadron Collider is presented. We observe a growing trend with energy now not only for the longitudinal and the outward but also for the sideward pion source radius. The pion homogeneity volume and the decoupling time are significantly larger than those measured at RHIC.Comment: 17 pages, 5 captioned figures, 1 table, authors from page 12, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/388

Higher harmonic anisotropic flow measurements of charged particles in Pb-Pb collisions at 2.76 TeV

We report on the first measurement of the triangular $v_3$, quadrangular $v_4$, and pentagonal $v_5$ charged particle flow in Pb-Pb collisions at 2.76 TeV measured with the ALICE detector at the CERN Large Hadron Collider. We show that the triangular flow can be described in terms of the initial spatial anisotropy and its fluctuations, which provides strong constraints on its origin. In the most central events, where the elliptic flow $v_2$ and $v_3$ have similar magnitude, a double peaked structure in the two-particle azimuthal correlations is observed, which is often interpreted as a Mach cone response to fast partons. We show that this structure can be naturally explained from the measured anisotropic flow Fourier coefficients.Comment: 10 pages, 4 figures, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/387

GISTs múltiplos em neurofibromatose tipo 1: diagnóstico incidental em paciente com abdome agudo Multiple GISTs in neurofibromatosis type 1: incidental diagnosis in a patient with acute abdomen

INTRODUÇÃO: Tem sido descrito na literatura incidência aumentada de tumores estromais gastrointestinais (GISTs) em portadores de neurofibromatose tipo 1. Estes tumores tipicamente ocorrem no intestino delgado e, frequentemente, são múltiplos. RELATO DO CASO: Diagnóstico incidental de GIST em um paciente portador de neurofibromatose tipo 1 com abdome agudo. No trans-operatório foi identificada apendicite retrocecal perfurada e massa neoplásica no jejuno proximal. A referida lesão ocupava aproximadamente 70% da circunferência do órgão e não apresentava invasão de estruturas adjacentes. Além disso, observaram-se dezenas de pequenos nódulos disseminados por toda a extensão do jejuno e íleo. O anatomopatológico revelou neoplasia compatível com GIST, com grau moderado de atipias, baixo índice mitótico (<5/50) e ausência de necrose. Na análise imunoistoquímica, as células neoplásicas foram positivas para CD-34 e CD-117 (c-KIT), e negativas para a desmina. Depois da operação, o uso do quimioterápico Imatinib foi indicado. Após período de acompanhamento de 12 meses, o paciente não demonstrou sinais de recidiva. CONCLUSÃO: A ocorrência de GISTs deve ser sempre lembrada na avaliação de pacientes com massas abdominais e neurofibromatose tipo 1, principalmente em intestino delgado. Muitas vezes o comportamento da neoplasia é favorável e o uso de Imatinib deve ser individualizado.<br>BACKGROUND: The literature described an increased incidence of gastrointestinal stromal tumors (GISTs) in patients with neurofibromatosis type 1. These tumors typically occur in the small intestine, and frequently are multiple. Often the behavior of the tumor in this association is more favorable than in sporadic cases. CASE REPORT: Incidental diagnosis of GIST was done in a patient with neurofibromatosis type 1 during treatment for acute abdomen. Trans-operatively was identified a retrocecal perforated appendicitis and a neoplastic mass in the proximal jejunum. The lesion occupied approximately 70% of the circumference of the organ and had no invasion of adjacent structures. Moreover, there were dozens of small nodules scattered throughout the length of the jejunum and ileum. The pathology revealed malignancy consistent with GIST, with moderate degree of atypia, low mitotic index (<5 / 50) and absence of necrosis. In immunohistochemical analysis, the neoplastic cells were positive for CD-34 and CD-117 (c-KIT), and negative for desmin. After surgery, the use of Imatinib chemotherapy was indicated. After a follow-up period of 12 months, the patient showed no signs of recurrence. CONCLUSION: GISTs should be considered in the presence of abdominal mass and neurofibromatosis type 1, affecting mainly small bowel. Sometimes Imatinib can be administered with good results in the control of the disease

Electroweak measurements in electron–positron collisions at w-boson-pair energies at lep

Contains fulltext : 121524.pdf (preprint version ) (Open Access

Higher harmonic anisotropic flow measurements of charged particles in Pb-Pb collisions at √sNN=2.76 TeV

We report on the first measurement of the triangular v3, quadrangular v4, and pentagonal v5 charged particle flow in Pb–Pb collisions at √sNN= 2.76 TeV measured with the ALICE detector at the CERN Large Hadron Collider. We show that the triangular flow can be described in terms of the initial spatial anisotropy and its fluctuations, which provides strong constraints on its origin. In the most central events, where the elliptic flow v2 and v3 have similar magnitude, a double peaked structure in the two-particle azimuthal correlations is observed, which is often interpreted as a Mach cone response to fast partons. We show that this structure can be naturally explained from the measured anisotropic flow Fourier coefficients