658 research outputs found
Mass Dependence of M3Y-Type Interactions and the Effects of Tensor Correlations
The mass dependence of the M3Y-type effective interactions and the effects of
tensor correlations are examined. Two-body nuclear matrix elements are obtained
by the lowest order constrained variational (LOCV) technique with and without
tensor correlations. We have found that the tensor correlations are important
especially in the triplet-even (TE) and tensor-even (TNE) channels in order to
reproduce the G-matrix elements obtained previously. Then M3Y-type potentials
for inelastic scattering are obtained by fitting our two-body matrix elements
to those of a sum of Yukawa functions for the mass numbers A=24, A=40 and A=90.Comment: 13 pages, 6 table
Quantum Distribution of Gaussian Keys with Squeezed States
A continuous key distribution scheme is proposed that relies on a pair of
canonically conjugate quantum variables. It allows two remote parties to share
a secret Gaussian key by encoding it into one of the two quadrature components
of a single-mode electromagnetic field. The resulting quantum cryptographic
information vs disturbance tradeoff is investigated for an individual attack
based on the optimal continuous cloning machine. It is shown that the
information gained by the eavesdropper then simply equals the information lost
by the receiver.Comment: 5 pages, RevTe
Realistic Model of the Nucleon Spectral Function in Few- and Many- Nucleon Systems
By analysing the high momentum features of the nucleon momentum distribution
in light and complex nuclei, it is argued that the basic two-nucleon
configurations generating the structure of the nucleon Spectral Function at
high values of the nucleon momentum and removal energy, can be properly
described by a factorised ansatz for the nuclear wave function, which leads to
a nucleon Spectral Function in the form of a convolution integral involving the
momentum distributions describing the relative and center-of-mass motion of a
correlated nucleon-nucleon pair embedded in the medium. The Spectral Functions
of and infinite nuclear matter resulting from the convolution formula
and from many-body calculations are compared, and a very good agreement in a
wide range of values of nucleon momentum and removal energy is found.
Applications of the model to the analysis of inclusive and exclusive processes
are presented, illustrating those features of the cross section which are
sensitive to that part of the Spectral Function which is governed by
short-range and tensor nucleon-nucleon correlations.Comment: 40 pages Latex , 16 ps figures available from the above e-mail
address or from [email protected]
(Sub)mm Interferometry Applications in Star Formation Research
This contribution gives an overview about various applications of (sub)mm
interferometry in star formation research. The topics covered are molecular
outflows, accretion disks, fragmentation and chemical properties of low- and
high-mass star-forming regions. A short outlook on the capabilities of ALMA is
given as well.Comment: 20 pages, 7 figures, in proceedings to "2nd European School on Jets
from Young Star: High Angular Resolution Observations". A high-resolution
version of the paper can be found at
http://www.mpia.de/homes/beuther/papers.htm
Production of Pairs Accompanied by Nuclear Dissociation in Ultra-Peripheral Heavy Ion Collision
We present the first data on pair production accompanied by nuclear
breakup in ultra-peripheral gold-gold collisions at a center of mass energy of
200 GeV per nucleon pair. The nuclear breakup requirement selects events at
small impact parameters, where higher-order corrections to the pair production
cross section should be enhanced. We compare the pair kinematic distributions
with two calculations: one based on the equivalent photon approximation, and
the other using lowest-order quantum electrodynamics (QED); the latter includes
the photon virtuality. The cross section, pair mass, rapidity and angular
distributions are in good agreement with both calculations. The pair transverse
momentum, , spectrum agrees with the QED calculation, but not with the
equivalent photon approach. We set limits on higher-order contributions to the
cross section. The and spectra are similar, with no evidence
for interference effects due to higher-order diagrams.Comment: 6 pages with 3 figures Slightly modified version that will appear in
Phys. Rev.
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
Estimating the Prevalence of Muscle Wasting, Weakness, and Sarcopenia in Hemodialysis Patients.
OBJECTIVES: Haemodialysis (HD) patients suffer from nutritional problems, which include muscle wasting, weakness, and cachexia, and are associated with poor clinical outcomes. The European Working Group for Sarcopenia in Older People (EWGSOP) and Foundations for the National Institute of Health (FNIH) have developed criteria for the assessment of sarcopenia, including the use of non-invasive techniques such as bioelectrical impedance assessment (BIA), anthropometry, and hand grip strength (HGS) dynamometry. This study investigated the prevalence of muscle wasting, weakness, and sarcopenia using the EWGSOP and FNIH criteria. METHODS: BIA was performed in 24 females (f) and 63 males (m) in the post-dialysis period. Total skeletal muscle mass and appendicular skeletal muscle mass were estimated and index values (i.e., muscle mass divided by height2 [kg/m2]) were calculated (Total Skeletal Muscle Index (TSMI) and Appendicular Skeletal Muscle Index (ASMI)). Mid-arm circumference and triceps skin-fold thickness were measured and mid-upper arm muscle circumference (MUAMC) calculated. HGS was measured using a standard protocol and Jamar dynamometer. Suggested cut-points for low muscle mass and grip strength were utilized using the EWGSOP and FNIH criteria with prevalence estimated, including sarcopenia. RESULTS: The prevalence varied depending on methodology: low TSMI (moderate and severe sarcopenia combined) was 55% for whole group: 21% (f) and 68% (m). Low ASMI was 32% for whole group: 25% (f) and 35% (m). Low MUAMC was 25% for whole group: 0% (f) and 30% (m). ASMI highly correlated with Body Mass Index (r = 0.78, P < .001) and MUAMC (r = 0.68, P < .001). Muscle weakness was high regardless of cut-points used (50-71% (f); 60-79% (m)). CONCLUSIONS: Internationally, this is the first study comparing measures of muscle mass (TSMM and ASMM by BIA and MUAMC) and muscle strength (HGS) using this specific methodology in a hemodialysis population. Future work is required to confirm findings
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Maritime aerosol network as a component of AERONET - First results and comparison with global aerosol models and satellite retrievals
The Maritime Aerosol Network (MAN) has been collecting data over the oceans since November 2006. Over 80 cruises were completed through early 2010 with deployments continuing. Measurement areas included various parts of the Atlantic Ocean, the Northern and Southern Pacific Ocean, the South Indian Ocean, the Southern Ocean, the Arctic Ocean and inland seas. MAN deploys Microtops hand-held sunphotometers and utilizes a calibration procedure and data processing traceable to AERONET. Data collection included areas that previously had no aerosol optical depth (AOD) coverage at all, particularly vast areas of the Southern Ocean. The MAN data archive provides a valuable resource for aerosol studies in maritime environments. In the current paper we present results of AOD measurements over the oceans, and make a comparison with satellite AOD retrievals and model simulations
Real Roots of Random Polynomials and Zero Crossing Properties of Diffusion Equation
We study various statistical properties of real roots of three different
classes of random polynomials which recently attracted a vivid interest in the
context of probability theory and quantum chaos. We first focus on gap
probabilities on the real axis, i.e. the probability that these polynomials
have no real root in a given interval. For generalized Kac polynomials, indexed
by an integer d, of large degree n, one finds that the probability of no real
root in the interval [0,1] decays as a power law n^{-\theta(d)} where \theta(d)
> 0 is the persistence exponent of the diffusion equation with random initial
conditions in spatial dimension d. For n \gg 1 even, the probability that they
have no real root on the full real axis decays like
n^{-2(\theta(2)+\theta(d))}. For Weyl polynomials and Binomial polynomials,
this probability decays respectively like \exp{(-2\theta_{\infty}} \sqrt{n})
and \exp{(-\pi \theta_{\infty} \sqrt{n})} where \theta_{\infty} is such that
\theta(d) = 2^{-3/2} \theta_{\infty} \sqrt{d} in large dimension d. We also
show that the probability that such polynomials have exactly k roots on a given
interval [a,b] has a scaling form given by \exp{(-N_{ab} \tilde
\phi(k/N_{ab}))} where N_{ab} is the mean number of real roots in [a,b] and
\tilde \phi(x) a universal scaling function. We develop a simple Mean Field
(MF) theory reproducing qualitatively these scaling behaviors, and improve
systematically this MF approach using the method of persistence with partial
survival, which in some cases yields exact results. Finally, we show that the
probability density function of the largest absolute value of the real roots
has a universal algebraic tail with exponent {-2}. These analytical results are
confirmed by detailed numerical computations.Comment: 32 pages, 16 figure
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