194 research outputs found
SiGe-on-insulator fabricated via germanium condensation following high-fluence Ge+ ion implantation
Cluster Transformation Coefficients for Structure and Dynamics Calculations in n-Particle Systems: Atoms, Nuclei, and Quarks
The structure and dynamics of an n-particle system are described with coupled
nonlinear Heisenberg's commutator equations where the nonlinear terms are
generated by the two-body interaction that excites the reference vacuum via
particle-particle and particle-hole excitations. Nonperturbative solutions of
the system are obtained with the use of dynamic linearization approximation and
cluster transformation coefficients. The dynamic linearization approximation
converts the commutator chain into an eigenvalue problem. The cluster
coefficients factorize the matrix elements of the (n)-particles or
particle-hole systems in terms of the matrix elements of the (n-1)-systems
coupled to a particle-particle, particle-hole, and hole-hole boson. Group
properties of the particle-particle, particle-hole, and hole-hole permutation
groups simplify the calculation of these coefficients. The particle-particle
vacuum-excitations generate superconductive diagrams in the dynamics of
3-quarks systems. Applications of the model to fermionic and bosonic systems
are discussed.Comment: 13 pages, 5 figures, Wigner Proceedings for Conference Wigner
Centenial Pecs, July 8-12, 200
Centrality and dE_{T}/d\etadN_{ch}/d\eta$ in Heavy Ion Collisions at Mid-Rapidity
The PHENIX experiment at RHIC has measured transverse energy and charged
particle multiplicity at mid-rapidity in Au + Au collisions at
= 19.6, 130, 62.4 and 200 GeV as a function of centrality. The presented
results are compared to measurements from other RHIC experiments, and
experiments at lower energies. The dependence of
and per pair of participants is consistent with logarithmic
scaling for the most central events. The centrality dependence of
and is similar at all measured incident
energies. At RHIC energies the ratio of transverse energy per charged particle
was found independent of centrality and growing slowly with . A
survey of comparisons between the data and available theoretical models is also
presented.Comment: Proccedings of the Workshop: Focus on Multiplcity at Bari, Italy,
June 17-19,2004. To be submitted to the Jornal of Physics, "Conference
series". Includes: 20 Pages, 15 figures, 3 Tables, 80 Referencie
Elliptic flow of charged particles in Pb-Pb collisions at 2.76 TeV
We report the first measurement of charged particle elliptic flow in Pb-Pb
collisions at 2.76 TeV with the ALICE detector at the CERN Large Hadron
Collider. The measurement is performed in the central pseudorapidity region
(||<0.8) and transverse momentum range 0.2< < 5.0 GeV/. The
elliptic flow signal v, measured using the 4-particle correlation method,
averaged over transverse momentum and pseudorapidity is 0.087 0.002
(stat) 0.004 (syst) in the 40-50% centrality class. The differential
elliptic flow v reaches a maximum of 0.2 near = 3
GeV/. Compared to RHIC Au-Au collisions at 200 GeV, the elliptic flow
increases by about 30%. Some hydrodynamic model predictions which include
viscous corrections are in agreement with the observed increase.Comment: 10 pages, 4 captioned figures, published version, figures at
http://aliceinfo.cern.ch/ArtSubmission/node/389
Nonlinear Time-Domain Strip Theory Formulation for Low-Speed Manoeuvering and Station-Keeping
Cross-sectional analysis of nutrition and serum uric acid in two Caucasian cohorts: the AusDiab Study and the Tromsø study
Lower Expression of TLR2 and SOCS-3 Is Associated with Schistosoma haematobium Infection and with Lower Risk for Allergic Reactivity in Children Living in a Rural Area in Ghana
Inflammatory diseases such as atopic disorders are a major health problem in the Western world, but their prevalence is also increasing in developing countries, especially in urban centres. There is increasing evidence that exposure to a rural environment with high burden of compounds derived from parasites and microorganisms is associated with protection from atopic disorders. Since urbanisation is progressing at a rapid pace, particularly in less-developed nations, there is a need to understand the molecular processes that control the progress towards the development of allergic diseases in developing countries. In this study we have examined a population of school children living in a rural area of Ghana, where helminth (worm) infections are prevalent and associated with protection from skin reactivity to house dust mite. Blood samples were collected from these children and analysed for the expression levels of several genes involved in the development of a pro allergic immune system. The results point at a potential molecular link that might explain the negative association between schistosome infections and allergies
K0S and Λ production in Pb-Pb collisions at sNN−−−−√=2.76 TeV
The ALICE measurement of K0S and Λ production at midrapidity in Pb-Pb collisions at sNN−−−√=2.76 TeV is presented. The transverse momentum (pT) spectra are shown for several collision centrality intervals and in the pT range from 0.4 GeV/c (0.6 GeV/c for Λ) to 12 GeV/c. The pT dependence of the Λ/K0S ratios exhibits maxima in the vicinity of 3 GeV/c, and the positions of the maxima shift towards higher pT with increasing collision centrality. The magnitude of these maxima increases by almost a factor of three between most peripheral and most central Pb-Pb collisions. This baryon excess at intermediate pT is not observed in pp interactions at s√=0.9 TeV and at s√=7 TeV. Qualitatively, the baryon enhancement in heavy-ion collisions is expected from radial flow. However, the measured pT spectra above 2 GeV/c progressively decouple from hydrodynamical-model calculations. For higher values of pT, models that incorporate the influence of the medium on the fragmentation and hadronization processes describe qualitatively the pT dependence of the Λ/K0S ratio
The relation between the most-massive star and its parental star cluster mass
We present a thorough literature study of the most-massive star, m_max, in
several young star clusters in order to assess whether or not star clusters are
populated from the stellar initial mass function (IMF) by random sampling over
the mass range 0.01 < m < 150 M_sol without being constrained by the cluster
mass, M_ecl. The data reveal a partition of the sample into lowest mass objects
(M_ecl < 10^2 M_sol), moderate mass clusters (10^2 M_sol < M_ecl < 10^3 M_sol)
and rich clusters above 10^3 M_sol. Additionally, there is a plateau of a
constant maximal star mass (m_max ~ 25 M_sol) for clusters with masses between
10^3 M_sol and 4 10^3 M_sol. Statistical tests of this data set reveal that the
hypothesis of random sampling from the IMF between 0.01 and 150 M_sol is highly
unlikely for star clusters more massive than 10^2 M_sol with a probability of p
~ 2 10^-7 for the objects with M_ecl between 10^2 M_sol and 10^3 M_sol and p ~
3 10^-9 for the more massive star clusters. Also, the spread of m_max values at
a given M_ecl is smaller than expected from random sampling. We suggest that
the basic physical process able to explain this dependence of stellar inventory
of a star cluster on its mass may be the interplay between stellar feedback and
the binding energy of the cluster-forming molecular cloud core. Given these
results, it would follow that an integrated galactic initial mass function
(IGIMF) sampled from such clusters would automatically be steeper in comparison
to the IMF within individual star clusters.Comment: 26 pages, 13 figures, 3 tables, accepted for publication in MNRA
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