19,535 research outputs found
To what extent does severity of loneliness vary among different mental health diagnostic groups: A cross-sectional study.
Loneliness is a common and debilitating problem in individuals with mental health disorders. However, our knowledge on severity of loneliness in different mental health diagnostic groups and factors associated with loneliness is poor, thus limiting the ability to target and improve loneliness interventions. The current study investigated the association between diagnoses and loneliness and explored whether psychological and social factors were related to loneliness. This study employed a cross-sectional design using data from a completed study which developed a measure of social inclusion. It included 192 participants from secondary, specialist mental health services with a primary diagnosis of psychotic disorders (n = 106), common mental disorders (n = 49), or personality disorders (n = 37). The study explored differences in loneliness between these broad diagnostic groups, and the relationship to loneliness of: affective symptoms, social isolation, perceived discrimination, and internalized stigma. The study adhered to the STROBE checklist for observational research. People with common mental disorders (MD = 3.94, CI = 2.15 to 5.72, P < 0.001) and people with personality disorders (MD = 4.96, CI = 2.88 to 7.05, P < 0.001) reported higher levels of loneliness compared to people with psychosis. These differences remained significant after adjustment for all psychological and social variables. Perceived discrimination and internalized stigma were also independently associated with loneliness and substantially contributed to a final explanatory model. The severity of loneliness varies between different mental health diagnostic groups. Both people with common mental disorders and personality disorders reported higher levels of loneliness than people with psychosis. Addressing perceived mental health discrimination and stigma may help to reduce loneliness
Reactor antineutrino spectra and their application to antineutrino-induced reactions. II
The antineutrino and electron spectra associated with various nuclear fuels are calculated. While there are substantial differences between the spectra of different uranium and plutonium isotopes, the dependence on the energy and flux of the fission-inducing neutrons is very weak. The resulting spectra can be used for the calculation of the antineutrino and electron spectra of an arbitrary nuclear reactor at various stages of its refueling cycle. The sources of uncertainties in the spectrum are identified and analyzed in detail. The exposure time dependence of the spectrum is also discussed. The averaged cross sections of the inverse neutron β decay, weak charged and neutral-current-induced deuteron disintegration, and the antineutrino-electron scattering are then evaluated using the resulting ν̅_e spectra.
[RADIOACTIVITY, FISSION 235U, 238U, (^239)Pu, (^240)Pu, (^241)Pu, antineutrino and electron spectra calculated. σ for ν̅ induced reactions analyzed.
3-Body Dynamics in a (1+1) Dimensional Relativistic Self-Gravitating System
The results of our study of the motion of a three particle, self-gravitating
system in general relativistic lineal gravity is presented for an arbitrary
ratio of the particle masses. We derive a canonical expression for the
Hamiltonian of the system and discuss the numerical solution of the resulting
equations of motion. This solution is compared to the corresponding
non-relativistic and post-Newtonian approximation solutions so that the
dynamics of the fully relativistic system can be interpretted as a correction
to the one-dimensional Newtonian self-gravitating system. We find that the
structure of the phase space of each of these systems yields a large variety of
interesting dynamics that can be divided into three distinct regions: annulus,
pretzel, and chaotic; the first two being regions of quasi-periodicity while
the latter is a region of chaos. By changing the relative masses of the three
particles we find that the relative sizes of these three phase space regions
changes and that this deformation can be interpreted physically in terms of the
gravitational interactions of the particles. Furthermore, we find that many of
the interesting characteristics found in the case where all of the particles
share the same mass also appears in our more general study. We find that there
are additional regions of chaos in the unequal mass system which are not
present in the equal mass case. We compare these results to those found in
similar systems.Comment: latex, 26 pages, 17 figures, high quality figures available upon
request; typos and grammar correcte
Dynamical N-body Equlibrium in Circular Dilaton Gravity
We obtain a new exact equilibrium solution to the N-body problem in a
one-dimensional relativistic self-gravitating system. It corresponds to an
expanding/contracting spacetime of a circle with N bodies at equal proper
separations from one another around the circle. Our methods are
straightforwardly generalizable to other dilatonic theories of gravity, and
provide a new class of solutions to further the study of (relativistic)
one-dimensional self-gravitating systems.Comment: 4 pages, latex, reference added, minor changes in wordin
On the Standard Approach to Renormalization Group Improvement
Two approaches to renormalization-group improvement are examined: the
substitution of the solutions of running couplings, masses and fields into
perturbatively computed quantities is compared with the systematic sum of all
the leading log (LL), next-to-leading log (NLL) etc. contributions to
radiatively corrected processes, with n-loop expressions for the running
quantities being responsible for summing N^{n}LL contributions. A detailed
comparison of these procedures is made in the context of the effective
potential V in the 4-dimensional O(4) massless model,
showing the distinction between these procedures at two-loop order when
considering the NLL contributions to the effective potential V.Comment: 6 page
Statistical Mechanics of Relativistic One-Dimensional Self-Gravitating Systems
We consider the statistical mechanics of a general relativistic
one-dimensional self-gravitating system. The system consists of -particles
coupled to lineal gravity and can be considered as a model of
relativistically interacting sheets of uniform mass. The partition function and
one-particle distitrubion functions are computed to leading order in
where is the speed of light; as results for the
non-relativistic one-dimensional self-gravitating system are recovered. We find
that relativistic effects generally cause both position and momentum
distribution functions to become more sharply peaked, and that the temperature
of a relativistic gas is smaller than its non-relativistic counterpart at the
same fixed energy. We consider the large-N limit of our results and compare
this to the non-relativistic case.Comment: latex, 60 pages, 22 figure
Cosmological Models in Two Spacetime Dimensions
Various physical properties of cosmological models in (1+1) dimensions are
investigated. We demonstrate how a hot big bang and a hot big crunch can arise
in some models. In particular, we examine why particle horizons do not occur in
matter and radiation models. We also discuss under what circumstances
exponential inflation and matter/radiation decoupling can happen. Finally,
without assuming any particular equation of state, we show that physical
singularities can occur in both untilted and tilted universe models if certain
assumptions are satisfied, similar to the (3+1)-dimensional cases.Comment: 22 pgs., 2 figs. (available on request) (revised version contains
`paper.tex' macro file which was omitted in earlier version
Chaos in an Exact Relativistic 3-body Self-Gravitating System
We consider the problem of three body motion for a relativistic
one-dimensional self-gravitating system. After describing the canonical
decomposition of the action, we find an exact expression for the 3-body
Hamiltonian, implicitly determined in terms of the four coordinate and momentum
degrees of freedom in the system. Non-relativistically these degrees of freedom
can be rewritten in terms of a single particle moving in a two-dimensional
hexagonal well. We find the exact relativistic generalization of this
potential, along with its post-Newtonian approximation. We then specialize to
the equal mass case and numerically solve the equations of motion that follow
from the Hamiltonian. Working in hexagonal-well coordinates, we obtaining
orbits in both the hexagonal and 3-body representations of the system, and plot
the Poincare sections as a function of the relativistic energy parameter . We find two broad categories of periodic and quasi-periodic motions that we
refer to as the annulus and pretzel patterns, as well as a set of chaotic
motions that appear in the region of phase-space between these two types.
Despite the high degree of non-linearity in the relativistic system, we find
that the the global structure of its phase space remains qualitatively the same
as its non-relativisitic counterpart for all values of that we could
study. However the relativistic system has a weaker symmetry and so its
Poincare section develops an asymmetric distortion that increases with
increasing . For the post-Newtonian system we find that it experiences a
KAM breakdown for : above which the near integrable regions
degenerate into chaos.Comment: latex, 65 pages, 36 figures, high-resolution figures available upon
reques
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