101 research outputs found
Josephson oscillation of a superfluid Fermi gas
Using the complete numerical solution of a time-dependent three-dimensional
mean-field model we study the Josephson oscillation of a superfluid Fermi gas
(SFG) at zero temperature formed in a combined axially-symmetric harmonic plus
one-dimensional periodic optical-lattice (OL) potentials after displacing the
harmonic trap along the axial OL axis. We study the dependence of Josephson
frequency on the strength of the OL potential. The Josephson frequency
decreases with increasing strength as found in the experiment of Cataliotti et
al. [Science 293 (2001) 843] for a Bose-Einstein condensate and of the
experiment of Pezze et al. [Phys. Rev. Lett. 93 (2004) 120401] for an ideal
Fermi gas. We demonstrate a breakdown of Josephson oscillation in the SFG for a
large displacement of the harmonic trap. These features of Josephson
oscillation of a SFG can be tested experimentally.Comment: 7 pages, 10 figure
Bright solitons and soliton trains in a fermion-fermion mixture
We use a time-dependent dynamical mean-field-hydrodynamic model to predict
and study bright solitons in a degenerate fermion-fermion mixture in a
quasi-one-dimensional cigar-shaped geometry using variational and numerical
methods. Due to a strong Pauli-blocking repulsion among identical
spin-polarized fermions at short distances there cannot be bright solitons for
repulsive interspecies fermion-fermion interactions. However, stable bright
solitons can be formed for a sufficiently attractive interspecies interaction.
We perform a numerical stability analysis of these solitons and also
demonstrate the formation of soliton trains. These fermionic solitons can be
formed and studied in laboratory with present technology.Comment: 5 pages, 7 figure
Amicable pairs and aliquot cycles for elliptic curves
An amicable pair for an elliptic curve E/Q is a pair of primes (p,q) of good
reduction for E satisfying #E(F_p) = q and #E(F_q) = p. In this paper we study
elliptic amicable pairs and analogously defined longer elliptic aliquot cycles.
We show that there exist elliptic curves with arbitrarily long aliqout cycles,
but that CM elliptic curves (with j not 0) have no aliqout cycles of length
greater than two. We give conjectural formulas for the frequency of amicable
pairs. For CM curves, the derivation of precise conjectural formulas involves a
detailed analysis of the values of the Grossencharacter evaluated at a prime
ideal P in End(E) having the property that #E(F_P) is prime. This is especially
intricate for the family of curves with j = 0.Comment: 53 page
ATLAS sensitivity to top quark and W boson polarization in events
Stringent tests on top quark production and decay mechanisms are provided by
the measurement of the top quark and W boson polarization. This paper presents
a detailed study of these two measurements with the ATLAS detector, in the
semileptonic (ttbar -> W W b bbar -> l nu j1 j2 b bbar) and dileptonic (ttbar
-> W W b bbar -> l nu l nu b bbar) ttbar channels. It is based on leading-order
Monte Carlo generators and on a fast simulation of the detector. A particular
attention is paid to the systematic uncertainties, which dominate the
statistical errors after one LHC year at low luminosity (10 fb^{-1}), and to
the background estimate. Combining results from both channel studies, the
longitudinal component of the W polarization (F\_0) can be measured with a 2%
accuracy and the right-handed component (F\_R) with a 1% precision with 10
fb^{-1}. Even though the top quarks in ttbar pairs are not polarized, a large
asymmetry is expected within the Standard Model in the like-spin versus
unlike-spin pair production. A 4% precision on this asymmetry measurement is
possible with 10 fb^{-1}, after combining results from both channel studies.
These promising results are converted in a sensitivity to new physics, such as
tWb anomalous couplings, top decay to charged Higgs boson, or new s-channels
(heavy resonance, gravitons) in ttbar production.Comment: 41+2 pages, 20 figures, ATLAS scientific note SN-ATLAS-2005-05
Health promoting settings in primary health care - "hÀlsotorg": an implementation analysis
Background
Sweden, like many other western countries, faces increasing rates of lifestyle
related diseases and corresponding rise in costs for health care. To meet these
challenges, a number of efforts have been introduced at different societal
levels. One such effort is "HĂ€lsotorg" (HS). HS is a new health promotion
setting that emerged in collaboration between the Swedish County Councils and
Apoteket AB, a state-owned pharmacy company. HS's overall aim was to improve
population health and facilitate inhabitants' responsibility for self-care. A
new National Public Health Policy, introduced in 2008, emphasizes more focus on
individual's needs and responsibility as well as strong need for county
councils to provide supportive environment for individual-centred health
services and increased health literacy among the population. In light of this
policy, there is a need to examine existing settings that can provide
supportive environment for individuals at community level. The aim of this
study was to explore HS's policy implementation at local level and analyse HS's
activities, in order to provide a deeper understanding of HS's potential as a
health promoting setting.
Methods
Materials included a survey and key documents related to the development and
nature of HS on local and national levels. A policy analysis inspired by Walt
and Gilson was used in data analysis. In addition, an analysis using the
principles of health promotion in relation to HS policy process and activities
was also carried out.
Results
The analysis illuminated strengths and weaknesses in the policy process, its
actors, contextual factors and activities. The health communication approach in
the analysed documents contained health promoting intentions but the health
promoting approach corresponding to a health promoting setting was neither
apparent nor shared among the stakeholders. This influenced the interpretation
and implementation of HS negatively.
Conclusions
The analysis indicates that HS has potential to be a valuable health promotion
setting for both population and individuals, given the strong intentions for a
health and empowerment building approach that is expressed in the documents.
However, for a more sustainable implementation of HS, there is need for an in-
depth understanding of the health promotion approach among HS stakeholders
Planck Intermediate Results II: Comparison of SunyaevâZeldovich measurements from Planck and from the Arcminute Microkelvin Imager for 11 galaxy clusters
A comparison is presented of SunyaevâZeldovich measurements for 11 galaxy clusters as obtained by Planck and by the ground-based interferom- eter, the Arcminute Microkelvin Imager. Assuming a universal spherically-symmetric Generalised Navarro, Frenk & White (GNFW) model for the cluster gas pressure profile, we jointly constrain the integrated Compton-Y parameter (Y500) and the scale radius (Ξ500) of each cluster. Our resulting constraints in the Y500 â Ξ500 2D parameter space derived from the two instruments overlap significantly for eight of the clusters, although, overall, there is a tendency for AMI to find the SunyaevâZeldovich signal to be smaller in angular size and fainter than Planck. Significant discrepancies exist for the three remaining clusters in the sample, namely A1413, A1914, and the newly-discovered Planck cluster PLCKESZ G139.59+24.18. The robustness of the analysis of both the Planck and AMI data is demonstrated through the use of detailed simulations, which also discount confusion from residual point (radio) sources and from diffuse astrophysical foregrounds as possible explanations for the discrepancies found. For a subset of our cluster sample, we have investigated the dependence of our results on the assumed pressure profile by repeating the analysis adopting the best-fitting GNFW profile shape which best matches X-ray observations. Adopting the best-fitting profile shape from the X-ray data does not, in general, resolve the discrepancies found in this subset of five clusters. Though based on a small sample, our results suggest that the adopted GNFW model may not be sufficiently flexible to describe clusters universally
Higher harmonic anisotropic flow measurements of charged particles in Pb-Pb collisions at 2.76 TeV
We report on the first measurement of the triangular , quadrangular
, and pentagonal charged particle flow in Pb-Pb collisions at 2.76
TeV measured with the ALICE detector at the CERN Large Hadron Collider. We show
that the triangular flow can be described in terms of the initial spatial
anisotropy and its fluctuations, which provides strong constraints on its
origin. In the most central events, where the elliptic flow and
have similar magnitude, a double peaked structure in the two-particle azimuthal
correlations is observed, which is often interpreted as a Mach cone response to
fast partons. We show that this structure can be naturally explained from the
measured anisotropic flow Fourier coefficients.Comment: 10 pages, 4 figures, published version, figures at
http://aliceinfo.cern.ch/ArtSubmission/node/387
Planck intermediate results I : Further validation of new Planck clusters with XMM-Newton
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