428 research outputs found
Modeling hospital infrastructure by optimizing quality, accessibility and efficiency via a mixed integer programming model
BACKGROUND: The majority of curative health care is organized in hospitals. As in most other countries, the current 94 hospital locations in the Netherlands offer almost all treatments, ranging from rather basic to very complex care. Recent studies show that concentration of care can lead to substantial quality improvements for complex conditions and that dispersion of care for chronic conditions may increase quality of care. In previous studies on allocation of hospital infrastructure, the allocation is usually only based on accessibility and/or efficiency of hospital care. In this paper, we explore the possibilities to include a quality function in the objective function, to give global directions to how the ‘optimal’ hospital infrastructure would be in the Dutch context. METHODS: To create optimal societal value we have used a mathematical mixed integer programming (MIP) model that balances quality, efficiency and accessibility of care for 30 ICD-9 diagnosis groups. Typical aspects that are taken into account are the volume-outcome relationship, the maximum accepted travel times for diagnosis groups that may need emergency treatment and the minimum use of facilities. RESULTS: The optimal number of hospital locations per diagnosis group varies from 12-14 locations for diagnosis groups which have a strong volume-outcome relationship, such as neoplasms, to 150 locations for chronic diagnosis groups such as diabetes and chronic obstructive pulmonary disease (COPD). CONCLUSIONS: In conclusion, our study shows a new approach for allocating hospital infrastructure over a country or certain region that includes quality of care in relation to volume per provider that can be used in various countries or regions. In addition, our model shows that within the Dutch context chronic care may be too concentrated and complex and/or acute care may be too dispersed. Our approach can relatively easily be adopted towards other countries or regions and is very suitable to perform a ‘what-if’ analysis
Clinical longevity of intracoronal restorations made of gold, lithium disilicate, leucite, and indirect resin composite:a systematic review and meta-analysis
OBJECTIVES: The aim of this systematic review and meta-analysis is to assess the comparative clinical success and survival of intracoronal indirect restorations using gold, lithium disilicate, leucite, and indirect composite materials.MATERIAL AND METHODS: This systematic review and meta-analysis were conducted following the Cochrane Handbook for Systematic Reviews of Interventions and PRISMA guidelines. The protocol for this study was registered in PROSPERO (registration number: CRD42021233185). A comprehensive literature search was conducted across various databases and sources, including PubMed/Medline, Embase, Cochrane Library, Web of Science, ClinicalTrials.gov, and gray literature. A total of 7826 articles were screened on title and abstract. Articles were not excluded based on the vitality of teeth, the language of the study, or the observation period. The risk difference was utilized for the analyses, and a random-effects model was applied. All analyses were conducted with a 95% confidence interval (95% CI). The calculated risk differences were derived from the combined data on restoration survival and failures obtained from each individual article. The presence of heterogeneity was assessed using the I2 statistic, and if present, the heterogeneity of the data in the articles was evaluated using the non-parametric chi-squared statistic (p < 0.05).RESULTS: A total of 12 eligible studies were selected, which included 946 restorations evaluated over a minimum observation period of 1 year and a maximum observation period of 7 years. Results of the meta-analysis indicated that intracoronal indirect resin composite restorations have an 18% higher rate of failure when compared to intracoronal gold restorations over 5-7 years of clinical service (risk difference =  - 0.18 [95% CI: - 0.27, - 0.09]; p = .0002; I2 = 0%). The meta-analysis examining the disparity in survival rates between intracoronal gold and leucite restorations could not be carried out due to methodological differences in the studies.CONCLUSIONS: According to the currently available evidence, medium-quality data indicates that lithium disilicate and indirect composite materials demonstrate comparable survival rates in short-term follow-up. Furthermore, intracoronal gold restorations showed significantly higher survival rates, making them a preferred option over intracoronal indirect resin-composite restorations. Besides that, the analysis revealed no statistically significant difference in survival rates between leucite and indirect composite restorations. The short observation period, limited number of eligible articles, and low sample size of the included studies were significant limitations.CLINICAL SIGNIFICANCE: Bearing in mind the limitations of the reviewed literature, this systematic review and meta-analysis help clinicians make evidence-based decisions on how to restore biomechanically compromised posterior teeth.</p
Towards Spinfoam Cosmology
We compute the transition amplitude between coherent quantum-states of
geometry peaked on homogeneous isotropic metrics. We use the holomorphic
representations of loop quantum gravity and the
Kaminski-Kisielowski-Lewandowski generalization of the new vertex, and work at
first order in the vertex expansion, second order in the graph (multipole)
expansion, and first order in 1/volume. We show that the resulting amplitude is
in the kernel of a differential operator whose classical limit is the canonical
hamiltonian of a Friedmann-Robertson-Walker cosmology. This result is an
indication that the dynamics of loop quantum gravity defined by the new vertex
yields the Friedmann equation in the appropriate limit.Comment: 8 page
Noncommutative Geometry of Finite Groups
A finite set can be supplied with a group structure which can then be used to
select (classes of) differential calculi on it via the notions of left-, right-
and bicovariance. A corresponding framework has been developed by Woronowicz,
more generally for Hopf algebras including quantum groups. A differential
calculus is regarded as the most basic structure needed for the introduction of
further geometric notions like linear connections and, moreover, for the
formulation of field theories and dynamics on finite sets. Associated with each
bicovariant first order differential calculus on a finite group is a braid
operator which plays an important role for the construction of distinguished
geometric structures. For a covariant calculus, there are notions of invariance
for linear connections and tensors. All these concepts are explored for finite
groups and illustrated with examples. Some results are formulated more
generally for arbitrary associative (Hopf) algebras. In particular, the problem
of extension of a connection on a bimodule (over an associative algebra) to
tensor products is investigated, leading to the class of `extensible
connections'. It is shown that invariance properties of an extensible
connection on a bimodule over a Hopf algebra are carried over to the extension.
Furthermore, an invariance property of a connection is also shared by a `dual
connection' which exists on the dual bimodule (as defined in this work).Comment: 34 pages, Late
Differential Geometry of Group Lattices
In a series of publications we developed "differential geometry" on discrete
sets based on concepts of noncommutative geometry. In particular, it turned out
that first order differential calculi (over the algebra of functions) on a
discrete set are in bijective correspondence with digraph structures where the
vertices are given by the elements of the set. A particular class of digraphs
are Cayley graphs, also known as group lattices. They are determined by a
discrete group G and a finite subset S. There is a distinguished subclass of
"bicovariant" Cayley graphs with the property that ad(S)S is contained in S.
We explore the properties of differential calculi which arise from Cayley
graphs via the above correspondence. The first order calculi extend to higher
orders and then allow to introduce further differential geometric structures.
Furthermore, we explore the properties of "discrete" vector fields which
describe deterministic flows on group lattices. A Lie derivative with respect
to a discrete vector field and an inner product with forms is defined. The
Lie-Cartan identity then holds on all forms for a certain subclass of discrete
vector fields.
We develop elements of gauge theory and construct an analogue of the lattice
gauge theory (Yang-Mills) action on an arbitrary group lattice. Also linear
connections are considered and a simple geometric interpretation of the torsion
is established.
By taking a quotient with respect to some subgroup of the discrete group,
generalized differential calculi associated with so-called Schreier diagrams
are obtained.Comment: 51 pages, 11 figure
Noncommutative geometry and physics: a review of selected recent results
This review is based on two lectures given at the 2000 TMR school in Torino.
We discuss two main themes: i) Moyal-type deformations of gauge theories, as
emerging from M-theory and open string theories, and ii) the noncommutative
geometry of finite groups, with the explicit example of Z_2, and its
application to Kaluza-Klein gauge theories on discrete internal spaces.Comment: Based on lectures given at the TMR School on contemporary string
theory and brane physics, Jan 26- Feb 2, 2000, Torino, Italy. To be published
in Class. Quant. Grav. 17 (2000). 3 ref.s added, typos corrected, formula on
exterior product of n left-invariant one-forms corrected, small changes in
the Sect. on integratio
Classification of bicovariant differential calculi on the Jordanian quantum groups GL_{g,h}(2) and SL_{h}(2) and quantum Lie algebras
We classify all 4-dimensional first order bicovariant calculi on the
Jordanian quantum group GL_{h,g}(2) and all 3-dimensional first order
bicovariant calculi on the Jordanian quantum group SL_{h}(2). In both cases we
assume that the bicovariant bimodules are generated as left modules by the
differentials of the quantum group generators. It is found that there are 3
1-parameter families of 4-dimensional bicovariant first order calculi on
GL_{h,g}(2) and that there is a single, unique, 3-dimensional bicovariant
calculus on SL_{h}(2). This 3-dimensional calculus may be obtained through a
classical-like reduction from any one of the three families of 4-dimensional
calculi on GL_{h,g}(2). Details of the higher order calculi and also the
quantum Lie algebras are presented for all calculi. The quantum Lie algebra
obtained from the bicovariant calculus on SL_{h}(2) is shown to be isomorphic
to the quantum Lie algebra we obtain as an ad-submodule within the Jordanian
universal enveloping algebra U_{h}(sl(2)) and also through a consideration of
the decomposition of the tensor product of two copies of the deformed adjoint
module. We also obtain the quantum Killing form for this quantum Lie algebra.Comment: 33 pages, AMSLaTeX, misleading remark remove
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