281 research outputs found
Strangeness production time and the K+/pi+ horn
We construct a hadronic kinetic model which describes production of strange
particles in ultrarelativistic nuclear collisions in the energy domain of SPS.
We test this model on description of the sharp peak in the excitation function
of multiplicity ratio K+/pi+ and demonstrate that hadronic model reproduces
these data rather well. The model thus must be tested on other types of data in
order to verify the hypothesis that deconfinement sets in at lowest SPS
energies.Comment: proceedings of Hot Quarks 0
Center or Limit Cycle: Renormalization Group as a Probe
Based on our studies done on two-dimensional autonomous systems, forced
non-autonomous systems and time-delayed systems, we propose a unified
methodology - that uses renormalization group theory - for finding out
existence of periodic solutions in a plethora of nonlinear dynamical systems
appearing across disciplines. The technique will be shown to have a non-trivial
ability of classifying the solutions into limit cycles and periodic orbits
surrounding a center. Moreover, the methodology has a definite advantage over
linear stability analysis in analyzing centers
Homogeneous nucleation of quark-gluon plasma, finite size effects and long-lived metastable objects
The general formalism of homogeneous nucleation theory is applied to study
the hadronization pattern of the ultra-relativistic quark-gluon plasma (QGP)
undergoing a first order phase transition. A coalescence model is proposed to
describe the evolution dynamics of hadronic clusters produced in the nucleation
process. The size distribution of the nucleated clusters is important for the
description of the plasma conversion. The model is most sensitive to the
initial conditions of the QGP thermalization, time evolution of the energy
density, and the interfacial energy of the plasma-hadronic matter interface.
The rapidly expanding QGP is first supercooled by about . Then it reheats again up to the critical temperature T_c. Finally it
breaks up into hadronic clusters and small droplets of plasma. This fast
dynamics occurs within the first . The finite size effects and
fluctuations near the critical temperature are studied. It is shown that a drop
of longitudinally expanding QGP of the transverse radius below 4.5 fm can
display a long-lived metastability. However, both in the rapid and in the
delayed hadronization scenario, the bulk pion yield is emitted by sources as
large as 3-4.5 fm. This may be detected experimentally both by a HBT
interferometry signal and by the analysis of the rapidity distributions of
particles in narrow p_T-intervals at small p_T on an event-by-event basis.Comment: 29 pages, incl. 12 figures and 1 table; to be published in Phys. Rev.
Hyperon production in Ar+KCl collisions at 1.76A GeV
We present transverse momentum spectra, rapidity distribution and
multiplicity of Lambda-hyperons measured with the HADES spectrometer in the
reaction Ar(1.76A GeV)+KCl. The yield of Xi- is calculated from our previously
reported Xi-/(Lambda+Sigma0) ratio and compared to other strange particle
multiplicities. Employing a strangeness balance equation the multiplicities of
the yet unmeasured charged Sigma hyperons can be estimated. Finally a
statistical hadronization model is used to fit the yields of pi-, K+, K0s, K-,
phi, Lambda and Xi-. The resulting chemical freeze-out temperature of T=(76+-2)
MeV is compared to the measured slope parameters obtained from fits to the
transverse mass distributions of the particles
Variability of humidity conditions in the Arctic during the first International Polar Year, 1882-83
Of all the early instrumental data for the Arctic, the meteorological data gathered during the first International Polar Year, in 1882–83 (IPY-1), are the best in terms of coverage, quality and resolution. Research carried out during IPY-1 scientific expeditions brought a significant contribution to the development of hygrometry in polar regions at the end of the 19th century. The present paper gives a detailed analysis of a unique series of humidity measurements that were carried out during IPY-1 at hourly resolutions at nine meteorological stations, relatively evenly distributed in the High Arctic. It gives an overall view of the humidity conditions prevalent in the Arctic at that time. The results show that the spatial distribution of atmospheric water vapour pressure (e) and relative humidity (RH) in the Arctic during IPY-1 was similar to the present. In the annual course the highest values of e were noted in July and August, while the lowest occurred in the cold half of the year. In comparison to present-day conditions (1961–1990), the mean values of RH in the IPY-1 period (September 1882 to July 1883) were higher by 2.4–5.6%. Most of the changes observed between historical and modern RH values are not significant. The majority of historical daily RH values lie between a distance of less than two standard deviations from current long-term monthly means
Human Resource Flexibility as a Mediating Variable Between High Performance Work Systems and Performance
Much of the human resource management literature has demonstrated the impact of high performance
work systems (HPWS) on organizational performance. A new generation of studies is
emerging in this literature that recommends the inclusion of mediating variables between HPWS
and organizational performance. The increasing rate of dynamism in competitive environments
suggests that measures of employee adaptability should be included as a mechanism that may
explain the relevance of HPWS to firm competitiveness. On a sample of 226 Spanish firms, the
study’s results confirm that HPWS influences performance through its impact on the firm’s
human resource (HR) flexibility
The Theory of Brown Dwarfs and Extrasolar Giant Planets
Straddling the traditional realms of the planets and the stars, objects below
the edge of the main sequence have such unique properties, and are being
discovered in such quantities, that one can rightly claim that a new field at
the interface of planetary science and and astronomy is being born. In this
review, we explore the essential elements of the theory of brown dwarfs and
giant planets, as well as of the new spectroscopic classes L and T. To this
end, we describe their evolution, spectra, atmospheric compositions, chemistry,
physics, and nuclear phases and explain the basic systematics of
substellar-mass objects across three orders of magnitude in both mass and age
and a factor of 30 in effective temperature. Moreover, we discuss the
distinctive features of those extrasolar giant planets that are irradiated by a
central primary, in particular their reflection spectra, albedos, and transits.
Aspects of the latest theory of Jupiter and Saturn are also presented.
Throughout, we highlight the effects of condensates, clouds, molecular
abundances, and molecular/atomic opacities in brown dwarf and giant planet
atmospheres and summarize the resulting spectral diagnostics. Where possible,
the theory is put in its current observational context.Comment: 67 pages (including 36 figures), RMP RevTeX LaTeX, accepted for
publication in the Reviews of Modern Physics. 30 figures are color. Most of
the figures are in GIF format to reduce the overall size. The full version
with figures can also be found at:
http://jupiter.as.arizona.edu/~burrows/papers/rm
Anxiety as a cause of attachment avoidance in women with Turner Syndrome
Working models of attachment are internal depictions of self relative to others and have been described in terms of two dimensions: (1) attachment avoidance and (2) attachment anxiety. An exploratory qualitative study was carried out to build understandings about women with Turner Syndrome (TS) and the psychosocial impact their infertility has upon salient relationships. In one-to-one semi-structured interviews, five women with TS were asked: How do you perceive your womanhood and infertility status has affected your relationships with: (1) the opposite sex, (2) siblings and (3) peers? In opposite-sex relationships, infertility status was found to arouse fear of ending up alone and anxiety over engaging in romantic relationships. In sibling relationships, jealousy was expressed in relation to disparity with sister(s) more natural maturation to womanhood, and, within peer relationships, consequences from divulging infertility status created attachment avoidance with friends. Further investigation in this area is merited
A search for the decay
We search for the rare flavor-changing neutral-current decay in a data sample of 82 fb collected with the {\sl BABAR}
detector at the PEP-II B-factory. Signal events are selected by examining the
properties of the system recoiling against either a reconstructed hadronic or
semileptonic charged-B decay. Using these two independent samples we obtain a
combined limit of
at the 90% confidence level. In addition, by selecting for pions rather than
kaons, we obtain a limit of using only the hadronic B reconstruction method.Comment: 7 pages, 8 postscript figures, submitted to Phys. Rev. Let
High-reflectivity broadband distributed Bragg reflector lattice matched to ZnTe
We report on the realization of a high quality distributed Bragg reflector
with both high and low refractive index layers lattice matched to ZnTe. Our
structure is grown by molecular beam epitaxy and is based on binary compounds
only. The high refractive index layer is made of ZnTe, while the low index
material is made of a short period triple superlattice containing MgSe, MgTe,
and ZnTe. The high refractive index step of Delta_n=0.5 in the structure
results in a broad stopband and the reflectivity coefficient exceeding 99% for
only 15 Bragg pairs.Comment: 4 pages, 3 figure
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