322 research outputs found
Would You Choose to be Happy? Tradeoffs Between Happiness and the Other Dimensions of Life in a Large Population Survey
A large literature documents the correlates and causes of subjective well-being, or happiness. But few studies have investigated whether people choose happiness. Is happiness all that people want from life, or are they willing to sacrifice it for other attributes, such as income and health? Tackling this question has largely been the preserve of philosophers. In this article, we find out just how much happiness matters to ordinary citizens. Our sample consists of nearly 13,000 members of the UK and US general populations. We ask them to choose between, and make judgments over, lives that are high (or low) in different types of happiness and low (or high) in income, physical health, family, career success, or education. We find that people by and large choose the life that is highest in happiness but health is by far the most important other concern, with considerable numbers of people choosing to be healthy rather than happy. We discuss some possible reasons for this preference
Collective flow in central Au-Au collisions at 150, 250 and 400 A MeV
Radial collective flow and thermalization are studied in gold on gold
collisions at 150, 250 and 400 A MeV bombarding energies with a
relativistically covariant formulation of a QMD code. We find that radial flow
and "thermal" energies calculated for all the charged fragments agree
reasonably with the experimental values. The experimental hardware filter at
small angles used in the FOPI experiments at higher energies selects mainly the
thermalized particles.Comment: 4 pages with 4 EPS figures included. Version accepted for publication
in Phys. Rev.
Momentum--dependent nuclear mean fields and collective flow in heavy ion collisions
We use the Boltzmann-Uehling-Uhlenbeck model to simulate the dynamical
evolution of heavy ion collisions and to compare the effects of two
parametrizations of the momentum--dependent nuclear mean field that have
identical properties in cold nuclear matter. We compare with recent data on
nuclear flow, as characterized by transverse momentum distributions and flow
() variables for symmetric and asymmetric systems. We find that the precise
functional dependence of the nuclear mean field on the particle momentum is
important. With our approach, we also confirm that the difference between
symmetric and asymmetric systems can be used to pin down the density and
momentum dependence of the nuclear self consistent one--body potential,
independently. All the data can be reproduced very well with a
momentum--dependent interaction with compressibility K = 210 MeV.Comment: 15 pages in ReVTeX 3.0; 12 postscript figures uuencoded; McGill/94-1
Hamiltonian structure and noncommutativity in -brane models with exotic supersymmetry
The Hamiltonian of the simplest super -brane model preserving 3/4 of the
D=4 N=1 supersymmetry in the centrally extended symplectic superspace is
derived and its symmetries are described. The constraints of the model are
covariantly separated into the first- and the second-class sets and the Dirac
brackets (D.B.) are constructed. We show the D.B. noncommutativity of the super
-brane coordinates and find the D.B. realization of the
superalgebra. Established is the coincidence of the D.B. and Poisson bracket
realizations of the superalgebra on the constraint surface and the
absence there of anomaly terms in the commutation relations for the quantized
generators of the superalgebra.Comment: Latex, 27 pages, no figures. Latex packages amsfonts and euscript are
use
Imaging Sources with Fast and Slow Emission Components
We investigate two-proton correlation functions for reactions in which fast
dynamical and slow evaporative proton emission are both present. In such cases,
the width of the correlation peak provides the most reliable information about
the source size of the fast dynamical component. The maximum of the correlation
function is sensitive to the relative yields from the slow and fast emission
components. Numerically inverting the correlation function allows one to
accurately disentangle fast dynamical from slow evaporative emission and
extract details of the shape of the two-proton source.Comment: 13 pages, 4 figure
Flow angle from intermediate mass fragment measurements
Directed sideward flow of light charged particles and intermediate mass
fragments was measured in different symmetric reactions at bombarding energies
from 90 to 800 AMeV. The flow parameter is found to increase with the charge of
the detected fragment up to Z = 3-4 and then turns into saturation for heavier
fragments. Guided by simple simulations of an anisotropic expanding thermal
source, we show that the value at saturation can provide a good estimate of the
flow angle, , in the participant region. It is found that
depends strongly on the impact parameter. The excitation
function of reveals striking deviations from the ideal
hydrodynamical scaling. The data exhibit a steep rise of \Theta_{\flow} to a
maximum at around 250-400 AMeV, followed by a moderate decrease as the
bombarding energy increases further.Comment: 28 pages Revtex, 6 figures (ps files), to appear in Nucl.Phys.
Two-Proton Correlations near Midrapidity in p+Pb and S+Pb Collisions at the CERN SPS
Correlations of two protons emitted near midrapidity in p+Pb collisions at
450 GeV/c and S+Pb collisions at 200A GeV/c are presented, as measured by the
NA44 Experiment. The correlation effect, which arises as a result of final
state interactions and Fermi-Dirac statistics, is related to the space-time
characteristics of proton emission. The measured source sizes are smaller than
the size of the target lead nucleus but larger than the sizes of the
projectiles. A dependence on the collision centrality is observed; the source
size increases with decreasing impact parameter. Proton source sizes near
midrapidity appear to be smaller than those of pions in the same interactions.
Quantitative agreement with the results of RQMD (v1.08) simulations is found
for p+Pb collisions. For S+Pb collisions the measured correlation effect is
somewhat weaker than that predicted by the model simulations, implying either a
larger source size or larger contribution of protons from long-lived particle
decays.Comment: 10 pages (LaTeX) text, 4 (EPS) figures; accepted for publication in
Phys. Lett.
Study of intermediate velocity products in the Ar+Ni collisions between 52 and 95 A.MeV
Intermediate velocity products in Ar+Ni collisions from 52 to 95 A.MeV are
studied in an experiment performed at the GANIL facility with the 4
multidetector INDRA. It is shown that these emissions cannot be explained by
statistical decays of the quasi-projectile and the quasi-target in complete
equilibrium. Three methods are used to isolate and characterize intermediate
velocity products. The total mass of these products increases with the violence
of the collision and reaches a large fraction of the system mass in mid-central
collisions. This mass is found independent of the incident energy, but strongly
dependent on the geometry of the collision. Finally it is shown that the
kinematical characteristics of intermediate velocity products are weakly
dependent on the experimental impact parameter, but strongly dependent on the
incident energy. The observed trends are consistent with a
participant-spectator like scenario or with neck emissions and/or break-up.Comment: 37 pages, 13 figure
Constraints on Dark Matter Annihilation in Clusters of Galaxies with the Fermi Large Area Telescope
Nearby clusters and groups of galaxies are potentially bright sources of
high-energy gamma-ray emission resulting from the pair-annihilation of dark
matter particles. However, no significant gamma-ray emission has been detected
so far from clusters in the first 11 months of observations with the Fermi
Large Area Telescope. We interpret this non-detection in terms of constraints
on dark matter particle properties. In particular for leptonic annihilation
final states and particle masses greater than ~200 GeV, gamma-ray emission from
inverse Compton scattering of CMB photons is expected to dominate the dark
matter annihilation signal from clusters, and our gamma-ray limits exclude
large regions of the parameter space that would give a good fit to the recent
anomalous Pamela and Fermi-LAT electron-positron measurements. We also present
constraints on the annihilation of more standard dark matter candidates, such
as the lightest neutralino of supersymmetric models. The constraints are
particularly strong when including the fact that clusters are known to contain
substructure at least on galaxy scales, increasing the expected gamma-ray flux
by a factor of ~5 over a smooth-halo assumption. We also explore the effect of
uncertainties in cluster dark matter density profiles, finding a systematic
uncertainty in the constraints of roughly a factor of two, but similar overall
conclusions. In this work, we focus on deriving limits on dark matter models; a
more general consideration of the Fermi-LAT data on clusters and clusters as
gamma-ray sources is forthcoming.Comment: accepted to JCAP, Corresponding authors: T.E. Jeltema and S. Profumo,
minor revisions to be consistent with accepted versio
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