Centrality evolution of the charged-particle pseudorapidity density over a broad pseudorapidity range in Pb-Pb collisions at root s(NN)=2.76TeV

Peer reviewe

FETAL CEREBRAL HEMORRHAGE DIAGNOSED ANTEPARTUM

The diagnosis of fetal cerebral hemorrhage (HCF) is less reported (0,9/1000 births) in comparison to the postpartum one. We presented 2 cases of fetal intraventricular hemorrhages diagnosed. Case 1: HCF diagnosed by ultrasound at the gestational age of 28 weeks and confirmed after birth by the presence of erythrocytes (significant number, pathological aspect) in the spinal fluid and by the modifications signaled by the transfontanellar ultrasound (severe internal hydrocephaly, minimum cerebral tissue). The death occurred after 24 hours postpartum (pathological exam: intraventricular cerebral hemorrhage). We mention the apparent lack of maternal risk factors, negative TORCH tests. Case 2: internal hydrocephaly at the age of 37 gestational weeks and confirmed in newborn (after cesarean section) by the clinical characteristic modifications, severe neurological impairment with modification at the transfontanellar ultrasound and the hemorrhagic and hypertensive aspect of the spinal fluid. We did not encounter maternal risk factors. Also, apparently, there were not any fetal risks: weight 2,820 grams at 37 gestational weeks, negative TORCH tests, negative cultures and CRP. The hydrocephaly had a progressive evolution imposing ventriculotomies and cysternotomies; the placement of a ventriculoperitoneal shunt during the third neurosurgical intervention improved the vital prognosis. Conclusions. The presence of hydrocephaly was a faithful ultrasound sign for the diagnosis of HCF. The evolution and the prognosis are influenced by the severity of hemorrhage and the gestational age. The survivors benefit from neurosurgical treatment. The multifactorial etiology, of the HCF incompletely elucidated leads to difficulties in establishing a target group of screening, in order to identify this lesion

HEMORAGIA CEREBRALĂ FETALĂ DIAGNOSTICATĂ ANTEPARTUM

Diagnosticul antepartum al hemoragiei cerebrale fetale (HCF) este mai puţin raportat (0,9/1.000 naşteri) comparativ cu cel postpartum. Sunt prezentate două cazuri de hemoragie intraventriculară fetală, diagnosticate ecografic antepartum. Cazul 1: HCF diagnosticată ecografic la vârsta gestaţională de 28 de săptamâni de gestaţie şi confirmată postnatal prin prezenţa în LCR a hematiilor (număr semnificativ, ratatinate) şi a modificărilor semnalate de ecografia transfontanelară (hidrocefalie internă severă, ţesut cerebral minim). Decesul a survenit la 24 de ore postpartum (ex. histopatologic: hemoragie cerebrală intraventriculară). Menţionăm absenţa aparentă a factorilor de risc materni, negativitatea testelor TORCH. Cazul 2: hidrocefalie internă la vârsta de 37 de săptămâni de gestaţie şi confirmată la nou-născut (după cezariană) de modificările clinice caracteristice, suferinţa neurologică severă asociată cu modificări la ecografia transfontanelară şi aspectul hemoragic şi hipertensiv al LCR. Nu au fost depistaţi factori de risc materni. De asemenea, aparent nu au existat riscuri fetale: greutatea 2.820 g la 37 de săptămâni de gestaţie, teste TORCH negative, culturi şi CRP negative. Hidrocefalia a avut o evoluţie progresivă impunând ventriculotomii şi cisternotomii; plasarea unui şunt ventriculo-peritoneal în timpul celei de-a treia intervenţii neurochirurgicale a ameliorat prognosticul vital. Concluzii. Prezenţa hidrocefaliei a fost un semn ecografic fidel pentru diagnosticul HCF. Evoluţia şi prognosticul sunt influenţate de severitatea hemoragiei şi de vârsta gestaţională. Supravieţuitorii beneficiază de tratamentul neurochirurgical. Etiopatogenia plurifactorială, incomplet descifrată a HCF conduce la dificultăţi în stabilirea unui grup ţintă de screening, în scopul identificării acestei leziuni

Transverse momentum spectra of charged particles in proton–proton collisions at √s=900 GeV with ALICE at the LHC

The inclusive charged particle transverse momentum distribution is measured in proton–proton collisions at s=900 GeV at the LHC using the ALICE detector. The measurement is performed in the central pseudorapidity region (|η|<0.8) over the transverse momentum range 0.15<pT<10 GeV/c. The correlation between transverse momentum and particle multiplicity is also studied. Results are presented for inelastic (INEL) and non-single-diffractive (NSD) events. The average transverse momentum for |η|<0.8 is 〈pT〉INEL=0.483±0.001 (stat.)±0.007 (syst.) GeV/c and 〈pT〉NSD=0.489±0.001 (stat.)±0.007 (syst.) GeV/c, respectively. The data exhibit a slightly larger 〈pT〉 than measurements in wider pseudorapidity intervals. The results are compared to simulations with the Monte Carlo event generators PYTHIA and PHOJET

Measurement of charged jet suppression in Pb-Pb collisions at √sNN = 2.76 TeV

A measurement of the transverse momentum spectra of jets in Pb-Pb collisions at sNN−−−√=2.76 TeV is reported. Jets are reconstructed from charged particles using the anti-kT jet algorithm with jet resolution parameters R of 0.2 and 0.3 in pseudo-rapidity |η|<0.5. The transverse momentum pT of charged particles is measured down to 0.15 GeV/c which gives access to the low pT fragments of the jet. Jets found in heavy-ion collisions are corrected event-by-event for average background density and on an inclusive basis (via unfolding) for residual background fluctuations and detector effects. A strong suppression of jet production in central events with respect to peripheral events is observed. The suppression is found to be similar to the suppression of charged hadrons, which suggests that substantial energy is radiated at angles larger than the jet resolution parameter R=0.3 considered in the analysis. The fragmentation bias introduced by selecting jets with a high pT leading particle, which rejects jets with a soft fragmentation pattern, has a similar effect on the jet yield for central and peripheral events. The ratio of jet spectra with R=0.2 and R=0.3 is found to be similar in Pb-Pb and simulated PYTHIA pp events, indicating no strong broadening of the radial jet structure in the reconstructed jets with R<0.3.

Freeze-out radii extracted from three-pion cumulants in pp, p–Pb and Pb–Pb collisions at the LHC

In high-energy collisions, the spatio-temporal size of the particle production region can be measured using the Bose–Einstein correlations of identical bosons at low relative momentum. The source radii are typically extracted using two-pion correlations, and characterize the system at the last stage of interaction, called kinetic freeze-out. In low-multiplicity collisions, unlike in high-multiplicity collisions, two-pion correlations are substantially altered by background correlations, e.g. mini-jets. Such correlations can be suppressed using three-pion cumulant correlations. We present the first measurements of the size of the system at freeze-out extracted from three-pion cumulant correlations in pp, p–Pb and Pb–Pb collisions at the LHC with ALICE. At similar multiplicity, the invariant radii extracted in p–Pb collisions are found to be 5–15% larger than those in pp, while those in Pb–Pb are 35–55% larger than those in p–Pb. Our measurements disfavor models which incorporate substantially stronger collective expansion in p–Pb as compared to pp collisions at similar multiplicity

Inclusive J/ψ production in pp collisions at √s=2.76 TeV

The ALICE Collaboration has measured inclusive J/ψ production in pp collisions at a center-of-mass energy √s=2.76 TeV at the LHC. The results presented in this Letter refer to the rapidity ranges |y|<0.9 and 2.5<y<4 and have been obtained by measuring the electron and muon pair decay channels, respectively. The integrated luminosities for the two channels are Linte=1.1 nb−1 and Lintμ=19.9 nb−1, and the corresponding signal statistics are NJ/ψe+e−=59±14 and NJ/ψμ+μ−=1364±53. We present dσJ/ψ/dy for the two rapidity regions under study and, for the forward-y range, d2σJ/ψ/dydpt in the transverse momentum domain 0<pt<8 GeV/c. The results are compared with previously published results at s=7 TeV and with theoretical calculations

Suppression of charged particle production at large transverse momentum in central Pb–Pb collisions at √sNN=2.76 TeV

Inclusive transverse momentum spectra of primary charged particles in Pb–Pb collisions at √sNN=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 |η|<0.8 and 0.3<pT<20 GeV/c are compared to the expectation in pp collisions at the same sNN, scaled by the number of underlying nucleon–nucleon collisions. The comparison is expressed in terms of the nuclear modification factor RAA. The result indicates only weak medium effects (RAA≈0.7) in peripheral collisions. In central collisions, RAA reaches a minimum of about 0.14 at pT=6–7 GeV/c and increases significantly at larger pT. The measured suppression of high-pT 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