6,025 research outputs found
Eta-Mesic Nucleus and COSY-GEM Data
The experimental data of the COSY-GEM Collaboration for the recoil-free
transfer reaction p (27Al, 3He) \pi - p' X, leading to the formation of bound
state of eta (\eta) meson in 25Mg nucleus, is reanalyzed in this paper. In
particular, predicted values of binding energy and half-width of the \eta
-mesic nucleus 25Mg\eta, given by different theoretical approaches, are
compared with the ones obtained from the experimental missing mass spectrum. It
is found that the spectrum can be explained reasonably well if interference
effect of another process, where \eta is not bound in 25Mg but is scattered by
the nucleus and emerge as a pion, is taken into account. The data also indicate
that the interaction between N*(1535) and a nucleus is attractive in nature.Comment: Invited talk at the International Symposium on Mesic Nuclei, Krakow,
16 June 201
Composite vertices that lead to soft form factors
The momentum-space cut-off parameter of hadronic vertex functions
is studied in this paper. We use a composite model where we can measure the
contributions of intermediate particle propagations to . We show that
in many cases a composite vertex function has a much smaller cut-off than its
constituent vertices, particularly when light constituents such as pions are
present in the intermediate state. This suggests that composite
meson-baryon-baryon vertex functions are rather soft, i.e., they have \Lambda
considerably less than 1 GeV. We discuss the origin of this softening of form
factors as well as the implications of our findings on the modeling of nuclear
reactions.Comment: REVTex, 19 pages, 5 figs(to be provided on request
Age at quitting smoking as a predictor of risk of cardiovascular disease incidence independent of smoking status, time since quitting and pack-years
BACKGROUND Risk prediction for CVD events has been shown to vary according to current smoking status, pack-years smoked over a lifetime, time since quitting and age at quitting. The latter two are closely and inversely related. It is not known whether the age at which one quits smoking is an additional important predictor of CVD events. The aim of this study was to determine whether the risk of CVD events varied according to age at quitting after taking into account current smoking status, lifetime pack-years smoked and time since quitting. FINDINGS We used the Cox proportional hazards model to evaluate the risk of developing a first CVD event for a cohort of participants in the Framingham Offspring Heart Study who attended the fourth examination between ages 30 and 74 years and were free of CVD. Those who quit before the median age of 37 years had a risk of CVD incidence similar to those who were never smokers. The incorporation of age at quitting in the smoking variable resulted in better prediction than the model which had a simple current smoker/non-smoker measure and the one that incorporated both time since quitting and pack-years. These models demonstrated good discrimination, calibration and global fit. The risk among those quitting more than 5 years prior to the baseline exam and those whose age at quitting was prior to 44 years was similar to the risk among never smokers. However, the risk among those quitting less than 5 years prior to the baseline exam and those who continued to smoke until 44 years of age (or beyond) was two and a half times higher than that of never smokers. CONCLUSIONS Age at quitting improves the prediction of risk of CVD incidence even after other smoking measures are taken into account. The clinical benefit of adding age at quitting to the model with other smoking measures may be greater than the associated costs. Thus, age at quitting should be considered in addition to smoking status, time since quitting and pack-years when counselling individuals about their cardiovascular risk.This research was supported by an NHMRC health services
research grant (no. 465130), an NHMRC/NHF PhD scholarship and a
Vichealth Fellowship
Deconfinement Phase Transition in an Expanding Quark system in Relaxation Time Approximation
We investigated the effects of nonequilibrium and collision terms on the
deconfinement phase transition of an expanding quark system in Friedberg-Lee
model in relaxation time approximation. By calculating the effective quark
potential, the critical temperature of the phase transition is dominated by the
mean field, while the collisions among quarks and mesons change the time
structure of the phase transition significantly.Comment: 7 pages, 7 figure
General method for extracting the quantum efficiency of dispersive qubit readout in circuit QED
We present and demonstrate a general three-step method for extracting the
quantum efficiency of dispersive qubit readout in circuit QED. We use active
depletion of post-measurement photons and optimal integration weight functions
on two quadratures to maximize the signal-to-noise ratio of the
non-steady-state homodyne measurement. We derive analytically and demonstrate
experimentally that the method robustly extracts the quantum efficiency for
arbitrary readout conditions in the linear regime. We use the proven method to
optimally bias a Josephson traveling-wave parametric amplifier and to quantify
different noise contributions in the readout amplification chain.Comment: 10 pages, 6 figure
Parameter Inference in the Pulmonary Circulation of Mice
This study focuses on parameter inference in a pulmonary blood cir- culation model for mice. It utilises a fluid dynamics network model that takes selected parameter values and aims to mimic features of the pulmonary haemody- namics under normal physiological and pathological conditions. This is of medical relevance as it allows monitoring of the progression of pulmonary hypertension. Constraint nonlinear optimization is successfully used to learn the parameter values
The Role of in Two-pion Exchange Three-nucleon Potential
In this paper we have studied the two-pion exchange three-nucleon potential
using an approximate chiral symmetry of the
strong interaction. The off-shell pion-nucleon scattering amplitudes obtained
from the Weinberg Lagangian are supplemented with contributions from the
well-known -term and the exchange. It is the role of the
-resonance in , which we have investigated in detail in the
framework of the Lagrangian field theory. The -contribution is quite
appreciable and, more significantly, it is dependent on a parameter Z which is
arbitrary but has the empirical bounds . We find that the
-contribution to the important parameters of the depends
on the choice of a value for Z, although the correction to the binding energy
of triton is not expected to be very sensitive to the variation of Z within its
bounds.Comment: 14 pages, LaTe
Toward a unified description of hadro- and photoproduction: S-wave pi- and eta-photoproduction amplitudes
The Chew-Mandelstam parameterization, which has been used extensively in the
two-body hadronic sector, is generalized in this exploratory study to the
electromagnetic sector by simultaneous fits to the pion- and
eta-photoproduction S-wave multipole amplitudes for center-of-mass energies
from the pion threshold through 1.61 GeV. We review the Chew-Mandelstam
parameterization in detail to clarify the theoretical content of the SAID
hadronic amplitude analysis and to place the proposed, generalized SAID
electromagnetic amplitudes in the context of earlier employed parameterized
forms. The parameterization is unitary at the two-body level, employing four
hadronic channels and the gamma-N electromagnetic channel. We compare the
resulting fit to the MAID parameterization and find qualitative agreement
though, numerically, the solution is somewhat different. Applications of the
extended parameterization to global fits of the photoproduction data and to
global fits of the combined hadronic and photoproduction data are discussed.Comment: 9 pages, 9 figures; added figures and tex
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