49 research outputs found
CCD BV and 2MASS photometric study of the open cluster NGC 1513
We present CCD BV and JHK 2MASS photometric data for the open cluster
NGC 1513. We observed 609 stars in the direction of the cluster up to a
limiting magnitude of mag. The star count method shows that the
centre of the cluster lies at ,
and its angular size is arcmin.
The optical and near-infrared two-colour diagrams reveal the colour excesses in
the direction of the cluster as , and
mag. These results are consistent with normal
interstellar extinction values. Optical and near-infrared Zero Age
Main-Sequences (ZAMS) provided an average distance modulus of
mag, which can be translated into a distance of
pc. Finally, using Padova isochrones we determined the metallicity
and age of the cluster as ( dex) and
, respectively.Comment: 15 pages, 12 figures and 4 tables, accepted for publication in
Astrophysics & Space Scienc
Protective effect of N-acetylcysteine against oxygen radical-mediated coronary artery injury
Suppression of charged particle production at large transverse momentum in central Pb-Pb collisions at TeV
Inclusive transverse momentum spectra of primary charged particles in Pb-Pb
collisions at = 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 and GeV/ are compared to the expectation in pp collisions at the same
, scaled by the number of underlying nucleon-nucleon
collisions. The comparison is expressed in terms of the nuclear modification
factor . The result indicates only weak medium effects ( 0.7) in peripheral collisions. In central collisions,
reaches a minimum of about 0.14 at -7GeV/ and increases
significantly at larger . The measured suppression of high- 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 = 2.76 TeV
The first measurement of two-pion Bose-Einstein correlations in central Pb-Pb
collisions at 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
Production of pions, kaons and protons in pp collisions at GeV with ALICE at the LHC
The production of , , , , p, and pbar at mid-rapidity
has been measured in proton-proton collisions at GeV with the
ALICE detector. Particle identification is performed using the specific energy
loss in the inner tracking silicon detector and the time projection chamber. In
addition, time-of-flight information is used to identify hadrons at higher
momenta. Finally, the distinctive kink topology of the weak decay of charged
kaons is used for an alternative measurement of the kaon transverse momentum
() spectra. Since these various particle identification tools give
the best separation capabilities over different momentum ranges, the results
are combined to extract spectra from = 100 MeV/ to 2.5 GeV/.
The measured spectra are further compared with QCD-inspired models which yield
a poor description. The total yields and the mean are compared with
previous measurements, and the trends as a function of collision energy are
discussed.Comment: 24 pages, 18 captioned figures, 5 tables, published version, figures
at http://aliceinfo.cern.ch/ArtSubmission/node/388
Study of W boson production in PbPb and pp collisions at sqrt(s[NN]) = 2.76 TeV
A measurement is presented of W-boson production in PbPb collisions carried
out at a nucleon-nucleon (NN) centre-of-mass energy sqrt(s[NN]) of 2.76 TeV at
the LHC using the CMS detector. In data corresponding to an integrated
luminosity of 7.3 inverse microbarns, the number of W to mu mu-neutrino decays
is extracted in the region of muon pseudorapidity abs(eta[mu])<2.1 and
transverse momentum pt[mu]>25 GeV. Yields of muons found per unit of
pseudorapidity correspond to (159 +/- 10 (stat.) +/- 12 (syst.)) 10E-8 W(plus)
and (154 +/- 10 (stat.) +/- 12 (syst.)) 10E-8 W(minus) bosons per minimum-bias
PbPb collision. The dependence of W production on the centrality of PbPb
collisions is consistent with a scaling of the yield by the number of
incoherent NN collisions. The yield of W bosons is also studied in a sample of
pp interactions at sqrt(s)= 2.76 TeV corresponding to an integrated luminosity
of 231 inverse nanobarns. The individual W(plus) and W(minus) yields in PbPb
and pp collisions are found to agree, once the neutron and proton content in Pb
nuclei is taken into account. Likewise, the difference observed in the
dependence of the positive and negative muon production on pseudorapidity is
consistent with next-to-leading order perturbative QCD calculations.Comment: Submitted to Physics Letters
Biostratigraphy and paleoecology of an unusual palynological record from the Aquidauana Formation, Late Pennsylvanian of ParanĂĄ Basin
Statics and dynamics of composite structures with embedded shape memory alloys
A new class of modern smart materials such as piezoelectric polymers and ceramics, electrorheological fluids, optical fibers and shape memory alloys have a great number of possible applications in many industrial and engineering fields. This number grows constantly encouraging scientists and engineers to study and analyze the behavior of the materials, range and ways of their best use.<br />Shape memory alloy reinforced composites are an extremely versatile class of materials. Shape memory alloys are characterized by: large internal forces, unique ability of changing its material properties, wide range of operational temperature, excellent damping properties and high durability. Mechanical and physical properties of SMA strongly depend on temperature and initial stresses. Changes in temperature and initial stresses involve changes in the volume fraction of martensite in the alloys. During the martensite transformation recovery stresses appear. These recovery stresses are not only a function of alloys temperature but also depend on initial strains. Using shape memory alloys as fibre reinforcement gives structures numerous adaptive capabilities. One of them is the controlling of motion and the vibration of structures.<br />In order to model accurately the behavior of composite structures with embedded shape memory alloy components three literature models have been carefully examined. These models have been studied according to their abilities to predict properly superelastic and shape memory effects associated with the thermomechanical behavior of shape memory alloys and special attention has been paid to the set of state variables chosen for each model (Tanaka, Liang and Rogers, Brinson)<br />The lecture illustrates stress-strain relationships for composite structures with embedded SMA fibres and their influence upon certain changes in natural frequencies and thermal buckling of selected composite structures. Governing equations based on the finite element method are formulated for beams, plates, and shells. Active frequency controlling can be used, for example, to avoid resonances in composite structures such as shafts, blades, aircraft wings, etc. The finite element analysis results are compared to those obtained from an analytical continuum solution.<br />The results of calculations demonstrate the potential effectiveness of SMA fiber- reinforcement in composite structural elements in the process of controlling the vibration. The effect of SMA fibers activation on the amplitude of vibration normalized with respect to the amplitude of the uncontrolled vibration can also be analyzed.<br />It can be clearly observed that the activation process of SMA wires involves an increase in the natural bending frequencies. This effect rises when both the temperature and initial strains are higher
Inner Cell Mass Localization of NANOG Precedes OCT3/4 in Rhesus Monkey Blastocysts
The mechanism by which the inner cell mass (ICM) and trophectoderm (TE) become specified is poorly understood. Considerable species variation is evident in the expression of lineage-specific and embryonic stem cell (ESC) regulatory markers. We sought to investigate localization patterns of these markers in rhesus macaque compact morulae and blastocysts. NANOG protein was restricted to the ICM of blastocysts. In contrast to a previous report, the expression of CDX2 was detected in the primate blastocyst, localized specifically to the TE. Unlike the mouse embryo, OCT4 protein was detected using two different antibodies in both the ICM and TE. The ubiquitous pattern of OCT4 expression is consistent with observations in human, cow, and pig embryos. Significantly, lack of restricted OCT4 protein, and ICM localization of NANOG in primate blastocysts, suggests that NANOG may determine inner cell mass fate more specifically during primate development or may be less susceptible to culture artifacts. These results contrast markedly with current mechanistic hypotheses, although other factors may lie upstream of NANOG to constitute a complex interactive network. This difference may also underlie observations that regulatory mechanisms in ESC differ between mice and primates