682 research outputs found
An Improved Shashlyk Calorimeter
Shashlyk electromagnetic calorimeter modules with an energy resolution of
about 3%/sqrt{E (GeV)} for 50-1000 MeV photons has been developed, and a
prototype tested. Details of these improved modules, including mechanical
construction, selection of wave shifting fibers and photo-detectors, and
development of a new scintillator with improved optical and mechanical
properties are described. How the modules will perform in a large calorimeter
was determined from prototype measurements. The experimentally determined
characteristics of the calorimeter prototype show energy resolution of
sigma_E/E=(1.96+-0.1)% \oplus (2.74+-0.05)%/sqrt{E}, time resolution of sigma_T
= (72+-4)/sqrt{E} \oplus (14+-2)/E (ps), where photon energy E is given in GeV
units and \oplus means a quadratic summation. A punch-through inefficiency of
photon detection was measured to be \epsilon = 5*10^{-5} (\Theta >5 mrad).Comment: 29 pages, 21 figure
HEMORAGIA DIGESTIVĂ ÎN PATOLOGIA PEDIATRICĂ
Hemoragia digestivă la copil poate evolua de la forma ocultă până la manifestări majore cu risc vital. Etiologia
cuprinde boli extradigestive (patologia acută a sistemului nervos, coagulopatii, hipertensiune portală etc.)
sau digestive (infecţioase, malformative, infl amatorii etc.) cu o frecvenţă nuanţată de vârstă. Anamneza
grevată de numeroase posibilităţi de eroare se completează cu o explorare sistematizată abordându-se:
gravitatea pierderii de sânge, refl ectarea acesteia asupra funcţiei organelor vitale, depistarea unei cauze
medicale sau a unei cauze chirurgicale preexistente (malformativă) sau dobândite. Tratamentul este nuanţat
de severitatea pierderii de sânge, de necesarul de medicamente cu impact etiopatogenetic. Endoscopia
digestivă, pe lângă rolul ei important ca metodă de diagnostic, reprezintă uneori şi o metodă terapeutică
FACTORI PREDISPOZANŢI AI CONSTIPAŢIEI CRONICE LA COPIL – STUDIU CLINIC PE 2 ANI
În ultimul deceniu constipaţia a devenit o problemă actuală de adresabilitate în serviciile de gastroenterologie
pediatrică.
Obiective. Ne-am propus un studiu pentru a identifi ca prevalenţa constipaţiei şi stabilirea unor corelaţii între
dietă şi mediul socio-familial la copii cu vârste cuprinse între 1 şi 17 ani, internaţi în serviciul de Gastroenterologie,
Spitalul Clinic de Urgenţă pentru Copii „Sfânta Maria“ Iaşi, în perioada 1 ianuarie 2012 – 1 ianuarie 2014.
Rezultate. Grupul de studiu a constat dintr-un lot de 994 de pacienţi, reprezentând 9,6% din totalul copiilor
spitalizaţi. În ceea ce priveşte prevalenţa constipaţiei nu am observat o diferenţă semnifi cativă între sexe, raportul F/M a fost de 1,3/1, dar am remarcat o proporţie semnifi cativă de pacienţi provenind din mediul urban
68% (676) faţă de 32% (318) din mediul rural. În ceea ce priveşte mediul socio-familial: 34% (338) dintre copii
trăiesc cu bunicii, 13,9% (139) provin din familii monoparentale, 6,7% (67) sunt în grija unui asistent maternal şi 2,6% (26) vin din centrele de plasament. În lotul studiat un procent mic de copii au fost alăptaţi, respectiv, 26,2% (261), în prima lună, 10,7% (107) timp de 3 luni în timp ce la 6 luni 98,1% (976) dintre copii au primit o formulă de lapte. Diversifi carea a fost făcută incorect în cazul a 41% (408) dintre pacienţi. Doar 14,6% (145) au raportat consumul zilnic de fructe şi legume, în timp ce 51,1% (508) au luat masa cel puţin o dată pe săptămână la restaurante de tip fast-food. 21,6% (214) practică sport cel puţin 2 ore/săptămână, în timp ce 48,7% (484) petrec cel puţin 3 ore/zi la televizor. 12,8% (128) dintre pacienţi sunt supraponderali şi 5,7% (57) obezi.
Concluzii. Constipaţia este o boala care afectează copiii de toate vârstele. Nu sunt diferenţe notabile între sexe.
Se remarcă o pondere crescută a pacienţilor din mediu urban cu predominanţa unui regim alimentar inadecvat,
lipsa activităţii fi zice, precum şi o pondere crescută a pacienţilor supraponderali. Un rol important în modifi cările psihologice îl deţine mediul socio-familial
Tunneling of quantum rotobreathers
We analyze the quantum properties of a system consisting of two nonlinearly
coupled pendula. This non-integrable system exhibits two different symmetries:
a permutational symmetry (permutation of the pendula) and another one related
to the reversal of the total momentum of the system. Each of these symmetries
is responsible for the existence of two kinds of quasi-degenerated states. At
sufficiently high energy, pairs of symmetry-related states glue together to
form quadruplets. We show that, starting from the anti-continuous limit,
particular quadruplets allow us to construct quantum states whose properties
are very similar to those of classical rotobreathers. By diagonalizing
numerically the quantum Hamiltonian, we investigate their properties and show
that such states are able to store the main part of the total energy on one of
the pendula. Contrary to the classical situation, the coupling between pendula
necessarily introduces a periodic exchange of energy between them with a
frequency which is proportional to the energy splitting between
quasi-degenerated states related to the permutation symmetry. This splitting
may remain very small as the coupling strength increases and is a decreasing
function of the pair energy. The energy may be therefore stored in one pendulum
during a time period very long as compared to the inverse of the internal
rotobreather frequency.Comment: 20 pages, 11 figures, REVTeX4 styl
Pion emission from the T2K replica target: method, results and application
The T2K long-baseline neutrino oscillation experiment in Japan needs precise
predictions of the initial neutrino flux. The highest precision can be reached
based on detailed measurements of hadron emission from the same target as used
by T2K exposed to a proton beam of the same kinetic energy of 30 GeV. The
corresponding data were recorded in 2007-2010 by the NA61/SHINE experiment at
the CERN SPS using a replica of the T2K graphite target. In this paper details
of the experiment, data taking, data analysis method and results from the 2007
pilot run are presented. Furthermore, the application of the NA61/SHINE
measurements to the predictions of the T2K initial neutrino flux is described
and discussed.Comment: updated version as published by NIM
Measurements of long-range near-side angular correlations in TeV proton-lead collisions in the forward region
Two-particle angular correlations are studied in proton-lead collisions at a
nucleon-nucleon centre-of-mass energy of TeV, collected
with the LHCb detector at the LHC. The analysis is based on data recorded in
two beam configurations, in which either the direction of the proton or that of
the lead ion is analysed. The correlations are measured in the laboratory
system as a function of relative pseudorapidity, , and relative
azimuthal angle, , for events in different classes of event
activity and for different bins of particle transverse momentum. In
high-activity events a long-range correlation on the near side, , is observed in the pseudorapidity range . This
measurement of long-range correlations on the near side in proton-lead
collisions extends previous observations into the forward region up to
. The correlation increases with growing event activity and is found
to be more pronounced in the direction of the lead beam. However, the
correlation in the direction of the lead and proton beams are found to be
compatible when comparing events with similar absolute activity in the
direction analysed.Comment: All figures and tables, along with any supplementary material and
additional information, are available at
https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2015-040.htm
Evidence for the strangeness-changing weak decay
Using a collision data sample corresponding to an integrated luminosity
of 3.0~fb, collected by the LHCb detector, we present the first search
for the strangeness-changing weak decay . No
hadron decay of this type has been seen before. A signal for this decay,
corresponding to a significance of 3.2 standard deviations, is reported. The
relative rate is measured to be
, where and
are the and fragmentation
fractions, and is the branching
fraction. Assuming is bounded between 0.1 and
0.3, the branching fraction would lie
in the range from to .Comment: 7 pages, 2 figures, All figures and tables, along with any
supplementary material and additional information, are available at
https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2015-047.htm
Study of the production of and hadrons in collisions and first measurement of the branching fraction
The product of the () differential production
cross-section and the branching fraction of the decay () is
measured as a function of the beauty hadron transverse momentum, ,
and rapidity, . The kinematic region of the measurements is and . The measurements use a data sample
corresponding to an integrated luminosity of collected by the
LHCb detector in collisions at centre-of-mass energies in 2011 and in 2012. Based on previous LHCb
results of the fragmentation fraction ratio, , the
branching fraction of the decay is
measured to be \begin{equation*} \mathcal{B}(\Lambda_b^0\rightarrow J/\psi
pK^-)= (3.17\pm0.04\pm0.07\pm0.34^{+0.45}_{-0.28})\times10^{-4},
\end{equation*} where the first uncertainty is statistical, the second is
systematic, the third is due to the uncertainty on the branching fraction of
the decay , and the
fourth is due to the knowledge of . The sum of the
asymmetries in the production and decay between and
is also measured as a function of and .
The previously published branching fraction of , relative to that of , is updated.
The branching fractions of are determined.Comment: 29 pages, 19figures. All figures and tables, along with any
supplementary material and additional information, are available at
https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2015-032.htm
flavour tagging using charm decays at the LHCb experiment
An algorithm is described for tagging the flavour content at production of
neutral mesons in the LHCb experiment. The algorithm exploits the
correlation of the flavour of a meson with the charge of a reconstructed
secondary charm hadron from the decay of the other hadron produced in the
proton-proton collision. Charm hadron candidates are identified in a number of
fully or partially reconstructed Cabibbo-favoured decay modes. The algorithm is
calibrated on the self-tagged decay modes and using of data collected by the LHCb
experiment at centre-of-mass energies of and
. Its tagging power on these samples of
decays is .Comment: All figures and tables, along with any supplementary material and
additional information, are available at
http://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2015-027.htm
Observation of a new chi_b state in radiative transitions to Upsilon(1S) and Upsilon(2S) at ATLAS
The chi_b(nP) quarkonium states are produced in proton-proton collisions at
the Large Hadron Collider (LHC) at sqrt(s) = 7 TeV and recorded by the ATLAS
detector. Using a data sample corresponding to an integrated luminosity of 4.4
fb^-1, these states are reconstructed through their radiative decays to
Upsilon(1S,2S) with Upsilon->mu+mu-. In addition to the mass peaks
corresponding to the decay modes chi_b(1P,2P)->Upsilon(1S)gamma, a new
structure centered at a mass of 10.530+/-0.005 (stat.)+/-0.009 (syst.) GeV is
also observed, in both the Upsilon(1S)gamma and Upsilon(2S)gamma decay modes.
This is interpreted as the chi_b(3P) system.Comment: 5 pages plus author list (18 pages total), 2 figures, 1 table,
corrected author list, matches final version in Physical Review Letter
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