895 research outputs found
General practice cooperatives: long waiting times for home visits due to long distances?
BACKGROUND: The introduction of large-scale out-of-hours GP cooperatives has led to questions about increased distances between the GP cooperatives and the homes of patients and the increasing waiting times for home visits in urgent cases. We studied the relationship between the patient's waiting time for a home visit and the distance to the GP cooperative. Further, we investigated if other factors (traffic intensity, home visit intensity, time of day, and degree of urgency) influenced waiting times. METHODS: Cross-sectional study at four GP cooperatives. We used variance analysis to calculate waiting times for various categories of traffic intensity, home visit intensity, time of day, and degree of urgency. We used multiple logistic regression analysis to calculate to what degree these factors affected the ability to meet targets in urgent cases. RESULTS: The average waiting time for 5827 consultations was 30.5 min. Traffic intensity, home visit intensity, time of day and urgency of the complaint all seemed to affect waiting times significantly. A total of 88.7% of all patients were seen within 1 hour. In the case of life-threatening complaints (U1), 68.8% of the patients were seen within 15 min, and 95.6% of those with acute complaints (U2) were seen within 1 hour. For patients with life-threatening complaints (U1) the percentage of visits that met the time target of 15 minuts decreased from 86.5% (less than 2.5 km) to 16.7% (equals or more than 20 km). DISCUSSION AND CONCLUSION: Although home visits waiting times increase with increasing distance from the GP cooperative, it appears that traffic intensity, home visit intensity, and urgency also influence waiting times. For patients with life-threatening complaints waiting times increase sharply with the distance
Ricci flows with unbounded curvature
We show that any noncompact Riemann surface admits a complete Ricci flow
g(t), t\in[0,\infty), which has unbounded curvature for all t\in[0,\infty).Comment: 12 pages, 1 figure; updated reference
Existence of Ricci flows of incomplete surfaces
We prove a general existence result for instantaneously complete Ricci flows
starting at an arbitrary Riemannian surface which may be incomplete and may
have unbounded curvature. We give an explicit formula for the maximal existence
time, and describe the asymptotic behaviour in most cases.Comment: 20 pages; updated to reflect galley proof correction
Low-Temperature Orientation Dependence of Step Stiffness on {111} Surfaces
For hexagonal nets, descriptive of {111} fcc surfaces, we derive from
combinatoric arguments a simple, low-temperature formula for the orientation
dependence of the surface step line tension and stiffness, as well as the
leading correction, based on the Ising model with nearest-neighbor (NN)
interactions. Our formula agrees well with experimental data for both Ag and
Cu{111} surfaces, indicating that NN-interactions alone can account for the
data in these cases (in contrast to results for Cu{001}). Experimentally
significant corollaries of the low-temperature derivation show that the step
line tension cannot be extracted from the stiffness and that with plausible
assumptions the low-temperature stiffness should have 6-fold symmetry, in
contrast to the 3-fold symmetry of the crystal shape. We examine Zia's exact
implicit solution in detail, using numerical methods for general orientations
and deriving many analytic results including explicit solutions in the two
high-symmetry directions. From these exact results we rederive our simple
result and explore subtle behavior near close-packed directions. To account for
the 3-fold symmetry in a lattice gas model, we invoke a novel
orientation-dependent trio interaction and examine its consequences.Comment: 11 pages, 8 figure
The Effects of Next-Nearest-Neighbor Interactions on the Orientation Dependence of Step Stiffness: Reconciling Theory with Experiment for Cu(001)
Within the solid-on-solid (SOS) approximation, we carry out a calculation of
the orientational dependence of the step stiffness on a square lattice with
nearest and next-nearest neighbor interactions. At low temperature our result
reduces to a simple, transparent expression. The effect of the strongest trio
(three-site, non pairwise) interaction can easily be incorporated by modifying
the interpretation of the two pairwise energies. The work is motivated by a
calculation based on nearest neighbors that underestimates the stiffness by a
factor of 4 in directions away from close-packed directions, and a subsequent
estimate of the stiffness in the two high-symmetry directions alone that
suggested that inclusion of next-nearest-neighbor attractions could fully
explain the discrepancy. As in these earlier papers, the discussion focuses on
Cu(001).Comment: 8 pages, 3 figures, submitted to Phys. Rev.
Morphology of ledge patterns during step flow growth of metal surfaces vicinal to fcc(001)
The morphological development of step edge patterns in the presence of
meandering instability during step flow growth is studied by simulations and
numerical integration of a continuum model. It is demonstrated that the kink
Ehrlich-Schwoebel barrier responsible for the instability leads to an invariant
shape of the step profiles. The step morphologies change with increasing
coverage from a somewhat triangular shape to a more flat, invariant steady
state form. The average pattern shape extracted from the simulations is shown
to be in good agreement with that obtained from numerical integration of the
continuum theory.Comment: 4 pages, 4 figures, RevTeX 3, submitted to Phys. Rev.
Competing mechanisms for step meandering in unstable growth
The meander instability of a vicinal surface growing under step flow
conditions is studied within a solid-on-solid model. In the absence of edge
diffusion the selected meander wavelength agrees quantitatively with the
continuum linear stability analysis of Bales and Zangwill [Phys. Rev. B {\bf
41}, 4400 (1990)]. In the presence of edge diffusion a local instability
mechanism related to kink rounding barriers dominates, and the meander
wavelength is set by one-dimensional nucleation. The long-time behavior of the
meander amplitude differs in the two cases, and disagrees with the predictions
of a nonlinear step evolution equation [O. Pierre-Louis et al., Phys. Rev.
Lett. {\bf 80}, 4221 (1998)]. The variation of the meander wavelength with the
deposition flux and with the activation barriers for step adatom detachment and
step crossing (the Ehrlich-Schwoebel barrier) is studied in detail. The
interpretation of recent experiments on surfaces vicinal to Cu(100) [T.
Maroutian et al., Phys. Rev. B {\bf 64}, 165401 (2001)] in the light of our
results yields an estimate for the kink barrier at the close packed steps.Comment: 8 pages, 7 .eps figures. Final version. Some errors in chapter V
correcte
Out-of-hours care in western countries: assessment of different organizational models
Contains fulltext :
81655.pdf (publisher's version ) (Open Access)BACKGROUND: Internationally, different organizational models are used for providing out-of-hours care. The aim of this study was to assess prevailing models in order to identify their potential strengths and weaknesses. METHODS: An international web-based survey was done in 2007 in a sample of purposefully selected key informants from 25 western countries. The questions concerned prevailing organizational models for out-of-hours care, the most dominant model in each country, perceived weaknesses, and national plans for changes in out-of-hours care. RESULTS: A total of 71 key informants from 25 countries provided answers. In most countries several different models existed alongside each other. The Accident and Emergency department was the organizational model most frequently used. Perceived weaknesses of this model concerned the coordination and continuity of care, its efficiency and accessibility. In about a third of the countries, the rota group was the most dominant organizational model for out-of-hours care. A perceived weakness of this model was lowered job satisfaction of physicians. The GP cooperative existed in a majority of the participating countries; no weaknesses were mentioned with respect to this model. Most of the countries had plans to change the out-of-hours care, mainly toward large scale organizations. CONCLUSION: GP cooperatives combine size of scale advantages with organizational features of strong primary care, such as high accessibility, continuity and coordination of care. While specific patients require other organizational models, the co-existence of different organizational models for out-of-hours care in a country may be less efficient for health systems
Measurement of the 187Re({\alpha},n)190Ir reaction cross section at sub-Coulomb energies using the Cologne Clover Counting Setup
Uncertainties in adopted models of particle+nucleus optical-model potentials
directly influence the accuracy in the theoretical predictions of reaction
rates as they are needed for reaction-network calculations in, for instance,
{\gamma}-process nucleosynthesis. The improvement of the {\alpha}+nucleus
optical-model potential is hampered by the lack of experimental data at
astrophysically relevant energies especially for heavier nuclei. Measuring the
Re187({\alpha},n)Ir190 reaction cross section at sub-Coulomb energies extends
the scarce experimental data available in this mass region and helps
understanding the energy dependence of the imaginary part of the
{\alpha}+nucleus optical-model potential at low energies. Applying the
activation method, after the irradiation of natural rhenium targets with
{\alpha}-particle energies of 12.4 to 14.1 MeV, the reaction yield and thus the
reaction cross section were determined via {\gamma}-ray spectroscopy by using
the Cologne Clover Counting Setup and the method of {\gamma}{\gamma}
coincidences. Cross-section values at five energies close to the
astrophysically relevant energy region were measured. Statistical model
calculations revealed discrepancies between the experimental values and
predictions based on widely used {\alpha}+nucleus optical-model potentials.
However, an excellent reproduction of the measured cross-section values could
be achieved from calculations based on the so-called Sauerwein-Rauscher
{\alpha}+nucleus optical-model potential. The results obtained indicate that
the energy dependence of the imaginary part of the {\alpha}+nucleus
optical-model potential can be described by an exponential decrease. Successful
reproductions of measured cross sections at low energies for {\alpha}-induced
reactions in the mass range 141{\leq}A{\leq}187 confirm the global character of
the Sauerwein-Rauscher potential
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