751 research outputs found
Inverse problem by Cauchy data on arbitrary subboundary for system of elliptic equations
We consider an inverse problem of determining coefficient matrices in an
-system of second-order elliptic equations in a bounded two dimensional
domain by a set of Cauchy data on arbitrary subboundary. The main result of the
article is as follows: If two systems of elliptic operators generate the same
set of partial Cauchy data on an arbitrary subboundary, then the coefficient
matrices of the first-order and zero-order terms satisfy the prescribed system
of first-order partial differential equations. The main result implies the
uniqueness of any two coefficient matrices provided that the one remaining
matrix among the three coefficient matrices is known
Prediction of potentially avoidable readmission risk in a division of general internal medicine.
The 30-day post-discharge readmission rate is a quality indicator that may reflect suboptimal care. The computerised algorithm SQLape® can retrospectively identify a potentially avoidable readmission (PARA) with high sensitivity and specificity. We retrospectively analysed the hospital stays of patients readmitted to the Department of Internal Medicine of the CHUV (Centre Hospitalier Universitaire Vaudois) in order to quantify the proportion of PARAs and derive a risk prediction model.
All hospitalisations between January 2009 and December 2011 in our division of general internal medicine were analysed. Readmissions within 30 days of discharge were categorised using SQLape®. The impact on PARAs was tested for various clinical and nonclinical factors. The performance of the developed model was compared with the well-validated LACE and HOSPITAL scores.
From a total of 11 074 hospital stays, 777 (7%) were followed with PARA within 30 days. By analysing a group of 6729 eligible stays, defined in particular by the patients' returning to their place of residence (home or residential care centre), we identified the following risk factors: ≥1 hospitalisation in the year preceding index admission, Charlson score >1, active cancer, hyponatraemia, length of stay >11 days, prescription of ≥15 different medications during the stay. These variables were used to derive a risk prediction model for PARA with a good discriminatory power (C-statistic 0.70) and calibration (p = 0.69). Patients were then classified as low (16.4%), intermediate (49.4%) or high (34.2%) risk of PARA. The estimated risk of PARA for each category was 3.5%, 8.7% and 19.6%, respectively. The LACE and the HOSPITAL scores were significantly correlated with the PARA risk. The discriminatory power of the LACE (C-statistic 0.61) and the HOSPITAL (C-statistic 0.54) were lower than our model.
Our model identifies patients at high risk of 30-day PARA with a good performance. It could be used to target transition of care interventions. Nevertheless, this model should be validated on more data and could be improved with additional parameters. Our results highlight the difficulty to generalise one model in the context of different healthcare systems
A General Setting for Geometric Phase of Mixed States Under an Arbitrary Nonunitary Evolution
The problem of geometric phase for an open quantum system is reinvestigated
in a unifying approach. Two of existing methods to define geometric phase, one
by Uhlmann's approach and the other by kinematic approach, which have been
considered to be distinct, are shown to be related in this framework. The
method is based upon purification of a density matrix by its uniform
decomposition and a generalization of the parallel transport condition obtained
from this decomposition. It is shown that the generalized parallel transport
condition can be satisfied when Uhlmann's condition holds. However, it does not
mean that all solutions of the generalized parallel transport condition are
compatible with those of Uhlmann's one. It is also shown how to recover the
earlier known definitions of geometric phase as well as how to generalize them
when degeneracy exists and varies in time.Comment: 4 pages, extended result
Local Analysis of Inverse Problems: H\"{o}lder Stability and Iterative Reconstruction
We consider a class of inverse problems defined by a nonlinear map from
parameter or model functions to the data. We assume that solutions exist. The
space of model functions is a Banach space which is smooth and uniformly
convex; however, the data space can be an arbitrary Banach space. We study
sequences of parameter functions generated by a nonlinear Landweber iteration
and conditions under which these strongly converge, locally, to the solutions
within an appropriate distance. We express the conditions for convergence in
terms of H\"{o}lder stability of the inverse maps, which ties naturally to the
analysis of inverse problems
PROPOSTA DE MODELOS DE CONTABILIZAÇÃO GERENCIAL PARA MEDIDAS DE GESTÃO AMBIENTAL
Acredita-se que a adoção de medidas de gestão ambiental por parte das empresasé fator condicionante à perpetuação dos negócios organizacionais. Seguindo essaideologia, o estudo objetiva propor modelos de contabilização gerencial para odesenvolvimento de atividades preventivas à ocorrência de impactos ambientaisnegativos ocasionados pelo processo produtivo das organizações. As informaçõesgeradas através da elaboração dos relatórios gerenciais permitem evidenciar oresultado da atividade, assim como avaliar a decisão de se realizar certoinvestimento na área ambiental. Vale lembrar que, a conquista da excelênciaambiental contribui sobremaneira para uma posição diferenciada da empresa nacorrida gerada pela concorrência mercadológica
Rescaling multipartite entanglement measures for mixed states
A relevant problem regarding entanglement measures is the following: Given an
arbitrary mixed state, how does a measure for multipartite entanglement change
if general local operations are applied to the state? This question is
nontrivial as the normalization of the states has to be taken into account.
Here we answer it for pure-state entanglement measures which are invariant
under determinant 1 local operations and homogeneous in the state coefficients,
and their convex-roof extension which quantifies mixed-state entanglement. Our
analysis allows to enlarge the set of mixed states for which these important
measures can be calculated exactly. In particular, our results hint at a
distinguished role of entanglement measures which have homogeneous degree 2 in
the state coefficients.Comment: Published version plus one important reference (Ref. [39]
Geometric Phase: a Diagnostic Tool for Entanglement
Using a kinematic approach we show that the non-adiabatic, non-cyclic,
geometric phase corresponding to the radiation emitted by a three level cascade
system provides a sensitive diagnostic tool for determining the entanglement
properties of the two modes of radiation. The nonunitary, noncyclic path in the
state space may be realized through the same control parameters which control
the purity/mixedness and entanglement. We show analytically that the geometric
phase is related to concurrence in certain region of the parameter space. We
further show that the rate of change of the geometric phase reveals its
resilience to fluctuations only for pure Bell type states. Lastly, the
derivative of the geometric phase carries information on both purity/mixedness
and entanglement/separability.Comment: 13 pages 6 figure
Interplay Between Time-Temperature-Transformation and the Liquid-Liquid Phase Transition in Water
We study the TIP5P water model proposed by Mahoney and Jorgensen, which is
closer to real water than previously-proposed classical pairwise additive
potentials. We simulate the model in a wide range of deeply supercooled states
and find (i) the existence of a non-monotonic ``nose-shaped'' temperature of
maximum density line and a non-reentrant spinodal, (ii) the presence of a low
temperature phase transition, (iii) the free evolution of bulk water to ice,
and (iv) the time-temperature-transformation curves at different densities.Comment: RevTeX4, 4 pages, 4 eps figure
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