8,888 research outputs found
Rethinking the patient: using Burden of Treatment Theory to understand the changing dynamics of illness
<b>Background</b> In this article we outline Burden of Treatment Theory, a new model of the relationship between sick people, their social networks, and healthcare services. Health services face the challenge of growing populations with long-term and life-limiting conditions, they have responded to this by delegating to sick people and their networks routine work aimed at managing symptoms, and at retarding - and sometimes preventing - disease progression. This is the new proactive work of patient-hood for which patients are increasingly accountable: founded on ideas about self-care, self-empowerment, and self-actualization, and on new technologies and treatment modalities which can be shifted from the clinic into the community. These place new demands on sick people, which they may experience as burdens of treatment.<p></p>
<b>Discussion</b> As the burdens accumulate some patients are overwhelmed, and the consequences are likely to be poor healthcare outcomes for individual patients, increasing strain on caregivers, and rising demand and costs of healthcare services. In the face of these challenges we need to better understand the resources that patients draw upon as they respond to the demands of both burdens of illness and burdens of treatment, and the ways that resources interact with healthcare utilization.<p></p>
<b>Summary</b> Burden of Treatment Theory is oriented to understanding how capacity for action interacts with the work that stems from healthcare. Burden of Treatment Theory is a structural model that focuses on the work that patients and their networks do. It thus helps us understand variations in healthcare utilization and adherence in different healthcare settings and clinical contexts
Characteristics of Vehicular Traffic Flow at a Roundabout
We construct a stochastic cellular automata model for the description of
vehicular traffic at a roundabout designed at the intersection of two
perpendicular streets. The vehicular traffic is controlled by a self-organized
scheme in which traffic lights are absent. This controlling method incorporates
a yield-at-entry strategy for the approaching vehicles to the circulating
traffic flow in the roundabout. Vehicular dynamics is simulated within the
framework of the probabilistic cellular automata and the delay experienced by
the traffic at each individual street is evaluated for specified time
intervals. We discuss the impact of the geometrical properties of the
roundabout on the total delay. We compare our results with traffic-light
signalisation schemes, and obtain the critical traffic volume over which the
intersection is optimally controlled through traffic light signalisation
schemes.Comment: 10 pages, 17 eps figures. arXiv admin note: text overlap with
arXiv:cond-mat/040107
Relativistic Quantum Thermodynamics of Ideal Gases in 2 Dimensions
In this work we study the behavior of relativistic ideal Bose and Fermi gases
in two space dimensions. Making use of polylogarithm functions we derive a
closed and unified expression for their densities. It is shown that both type
of gases are essentially inequivalent, and only in the non-relativistic limit
the spinless and equal mass Bose and Fermi gases are equivalent as known in the
literature.Comment: 6 pages, 1 figur
Influence of local carrying capacity restrictions on stochastic predator-prey models
We study a stochastic lattice predator-prey system by means of Monte Carlo
simulations that do not impose any restrictions on the number of particles per
site, and discuss the similarities and differences of our results with those
obtained for site-restricted model variants. In accord with the classic
Lotka-Volterra mean-field description, both species always coexist in two
dimensions. Yet competing activity fronts generate complex, correlated
spatio-temporal structures. As a consequence, finite systems display transient
erratic population oscillations with characteristic frequencies that are
renormalized by fluctuations. For large reaction rates, when the processes are
rendered more local, these oscillations are suppressed. In contrast with
site-restricted predator-prey model, we observe species coexistence also in one
dimension. In addition, we report results on the steady-state prey age
distribution.Comment: Latex, IOP style, 17 pages, 9 figures included, related movies
available at http://www.phys.vt.edu/~tauber/PredatorPrey/movies
Density dependent hadron field theory for hypernuclei
The Density Dependent Relativistic Hadron Field (DDRH) theory, previously
introduced and applied to isospin nuclei, is extended to hypernuclei by
including the octet hyperons. Infinite matter Dirac-Brueckner theory for octet
baryons and the derivation of in-medium DDRH baryon-meson vertices is
discussed. From the properties of Dirac-Brueckner interactions it is found that
hyperon and nucleon self-energies and vertices are related by the ratios of
free space coupling constants. This leads to simple scaling laws for the
in-medium hyperon and nucleon vertices. The model is applied in relativistic
DDRH mean-field calculations to singl$\Lambda nuclei. Free space N-Lambda
T-matrix results are used for the scalar vertex. As the only free parameter the
hyperon vector vertex scaling factor is adjusted to a selected set of
hypernuclear data. Spectroscopic data of single Lambda hypernuclei over the
full mass range are well described. The reduced Lambda spin-orbit splitting is
reproduced and found to be related closely the medium dependence of scalar and
vector interactions.Comment: 38 pages, 9 figure
-Algebras, the BV Formalism, and Classical Fields
We summarise some of our recent works on -algebras and quasi-groups
with regard to higher principal bundles and their applications in twistor
theory and gauge theory. In particular, after a lightning review of
-algebras, we discuss their Maurer-Cartan theory and explain that any
classical field theory admitting an action can be reformulated in this context
with the help of the Batalin-Vilkovisky formalism. As examples, we explore
higher Chern-Simons theory and Yang-Mills theory. We also explain how these
ideas can be combined with those of twistor theory to formulate maximally
superconformal gauge theories in four and six dimensions by means of
-quasi-isomorphisms, and we propose a twistor space action.Comment: 19 pages, Contribution to Proceedings of LMS/EPSRC Durham Symposium
Higher Structures in M-Theory, August 201
Twisted topological structures related to M-branes
Studying the M-branes leads us naturally to new structures that we call
Membrane-, Membrane^c-, String^K(Z,3)- and Fivebrane^K(Z,4)-structures, which
we show can also have twisted counterparts. We study some of their basic
properties, highlight analogies with structures associated with lower levels of
the Whitehead tower of the orthogonal group, and demonstrate the relations to
M-branes.Comment: 17 pages, title changed on referee's request, minor changes to
improve presentation, typos correcte
A Phase-Space Approach to Collisionless Stellar Systems Using a Particle Method
A particle method for reproducing the phase space of collisionless stellar
systems is described. The key idea originates in Liouville's theorem which
states that the distribution function (DF) at time t can be derived from
tracing necessary orbits back to t=0. To make this procedure feasible, a
self-consistent field (SCF) method for solving Poisson's equation is adopted to
compute the orbits of arbitrary stars. As an example, for the violent
relaxation of a uniform-density sphere, the phase-space evolution which the
current method generates is compared to that obtained with a phase-space method
for integrating the collisionless Boltzmann equation, on the assumption of
spherical symmetry. Then, excellent agreement is found between the two methods
if an optimal basis set for the SCF technique is chosen. Since this
reproduction method requires only the functional form of initial DFs but needs
no assumptions about symmetry of the system, the success in reproducing the
phase-space evolution implies that there would be no need of directly solving
the collisionless Boltzmann equation in order to access phase space even for
systems without any special symmetries. The effects of basis sets used in SCF
simulations on the reproduced phase space are also discussed.Comment: 16 pages w/4 embedded PS figures. Uses aaspp4.sty (AASLaTeX v4.0). To
be published in ApJ, Oct. 1, 1997. This preprint is also available at
http://www.sue.shiga-u.ac.jp/WWW/prof/hozumi/papers.htm
A Vehicular Traffic Flow Model Based on a Stochastic Acceleration Process
A new vehicular traffic flow model based on a stochastic jump process in
vehicle acceleration and braking is introduced. It is based on a master
equation for the single car probability density in space, velocity and
acceleration with an additional vehicular chaos assumption and is derived via a
Markovian ansatz for car pairs. This equation is analyzed using simple driver
interaction models in the spatial homogeneous case. Velocity distributions in
stochastic equilibrium, together with the car density dependence of their
moments, i.e. mean velocity and scattering and the fundamental diagram are
presented.Comment: 27 pages, 6 figure
HIFI spectroscopy of low-level water transitions in M82
We present observations of the rotational ortho-water ground transition, the
two lowest para-water transitions, and the ground transition of ionised
ortho-water in the archetypal starburst galaxy M82, performed with the HIFI
instrument on the Herschel Space Observatory. These observations are the first
detections of the para-H2O(111-000) (1113\,GHz) and ortho-H2O+(111-000)
(1115\,GHz) lines in an extragalactic source. All three water lines show
different spectral line profiles, underlining the need for high spectral
resolution in interpreting line formation processes. Using the line shape of
the para-H2O(111-000) and ortho-H2O+(111-000) absorption profile in conjunction
with high spatial resolution CO observations, we show that the (ionised) water
absorption arises from a ~2000 pc^2 region within the HIFI beam located about
~50 pc east of the dynamical centre of the galaxy. This region does not
coincide with any of the known line emission peaks that have been identified in
other molecular tracers, with the exception of HCO. Our data suggest that water
and ionised water within this region have high (up to 75%) area-covering
factors of the underlying continuum. This indicates that water is not
associated with small, dense cores within the ISM of M82 but arises from a more
widespread diffuse gas component.Comment: 5 pages, 4 figures. Accepted for publication in A&
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