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1.
Risk Anal ; 36(2): 396-410, 2016 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-26178458

RESUMO

Modeling the dependence between uncertainties in decision and risk analyses is an important part of the problem structuring process. We focus on situations where correlated uncertainties are discrete, and extend the concept of the copula-based approach for modeling correlated continuous uncertainties to the representation of correlated discrete uncertainties. This approach reduces the required number of probability assessments significantly compared to approaches requiring direct estimates of conditional probabilities. It also allows the use of multiple dependence measures, including product moment correlation, rank order correlation and tail dependence, and parametric families of copulas such as normal copulas, t-copulas, and Archimedean copulas. This approach can be extended to model the dependence between discrete and continuous uncertainties in the same event tree.


Assuntos
Algoritmos , Medição de Risco/métodos , Incerteza , Simulação por Computador , Tomada de Decisões , Modelos Estatísticos , Probabilidade , Análise de Sistemas
2.
Curr Diab Rep ; 13(2): 172-6, 2013 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-23225213

RESUMO

Early efforts to use point-of-care clinical decision support (CDS) were limited to the use of prompts and reminders, which improved test ordering but not intermediate outcomes of care, such as glucose, blood pressure, or lipid levels. More sophisticated diabetes CDS tools are now available that use electronic medical record data to provide patient-specific advice on medication use on the basis of previous treatment, distance from goal, and other clinical data. These tools have shown modest but significant improvement in glucose and blood pressure control. Promising next-generation developments will include prioritizing clinical actions that have maximum benefit to a given patient at the point of care and developing effective methods to communicate CDS information to patients to better incorporate patient preferences in care decisions.


Assuntos
Sistemas de Apoio a Decisões Clínicas , Glicemia , Pressão Sanguínea , Registros Eletrônicos de Saúde , Humanos
3.
Am J Manag Care ; 16(2): 102-6, 2010 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-20148614

RESUMO

OBJECTIVE: To evaluate the effects of providing appropriateness criteria through guideline-based electronic health record (EHR) decision support for high-tech diagnostic imaging (HTDI) procedures. STUDY DESIGN: Chart audits were performed on a random sample of adult primary care orders for 3 HTDI procedures (computed tomography [CT] and magnetic resonance imaging [MRI] of the head, and MRI of the lumbar spine) before and after implementation of an EHR decision support system. OUTCOME MEASURES: Level of appropriateness, abnormal findings, and apparent effects on patient care. RESULTS: A total of 299 eligible audits were performed. Decision support was associated with a 20% to 36% drop in spine MRI and head CT orders, but head MRI order volume was unaffected. Combined results for the 3 procedures showed that a larger proportion of studies ordered after implementing decision support (89.2% vs 79.5%, P = .02) fit appropriateness criteria, and more postimplementation studies had A ratings (highest utility rating) (81.8% vs 70%, P = .04). However, there were no differences in the proportion of tests with positive findings (42/132 vs 28/120, P = .16 among procedures that met definite criteria) or the proportion with a likely impact on patients (6.6% vs 10.8%, P = .07). CONCLUSIONS: These data support the feasibility of using chart audits to assess the relationship between appropriateness criteria and HTDI orders. Although introduction of EHR clinical decision support for diagnostic imaging orders was associated with reduced volume and increased appropriateness of orders, there was little apparent impact on either findings or patients.


Assuntos
Sistemas de Apoio a Decisões Clínicas , Diagnóstico por Imagem , Sistemas Computadorizados de Registros Médicos , Procedimentos Desnecessários , Prática de Grupo , Humanos , Auditoria Médica , Minnesota
4.
Phys Rev Lett ; 101(21): 218303, 2008 Nov 21.
Artigo em Inglês | MEDLINE | ID: mdl-19113457

RESUMO

We examine mixtures of DNA and filamentous actin (F-actin) as a model system of like-charged rigid rods and flexible chains. Confocal microscopy reveals the formation of elongated nematic F-actin domains reticulated via defect-free vertices into a network embedded in a mesh of random DNA. Synchrotron x-ray scattering results indicate that the DNA mesh squeezes the F-actin domains into a nematic state with an interactin spacing that decreases with increasing DNA concentration as d(actin) proportional, variantrho(DNA)(-1/2). Interestingly, the system changes from a counterion-controlled regime to a depletion-controlled regime with added salt, with drastic consequences for the osmotic pressure induced phase behavior.


Assuntos
Actinas/química , DNA/química , Animais , Géis/química , Gelsolina/química , Humanos , Microscopia Confocal , Estrutura Terciária de Proteína , Coelhos , Espalhamento a Baixo Ângulo , Termodinâmica , Difração de Raios X
5.
Proc Natl Acad Sci U S A ; 103(21): 7962-7, 2006 May 23.
Artigo em Inglês | MEDLINE | ID: mdl-16690742

RESUMO

Current understanding of electrostatics in water is based on mean-field theories like the Poisson-Boltzmann formalism and its approximations, which are routinely used in colloid science and computational biology. This approach, however, breaks down for highly charged systems, which exhibit counterintuitive phenomena such as overcharging and like-charge attraction. Models of counterion correlations have been proposed as possible explanations, but no experimental comparisons are available. Here, collective dynamics of counterions that mediate like-charge attraction between F-actin filaments have been directly observed in aqueous solution using high-resolution inelastic x-ray scattering down to molecular length-scales. We find a previously undescribed acoustic-like phonon mode associated with correlated counterions. The excitation spectra at high wave-vector Q reveal unexpected dynamics due to ions interacting with their "cages" of nearest neighbors. We examine this behavior in the context of intrinsic charge density variations on F-actin. The measured speed of sound and collective relaxation rates in this liquid agree surprisingly well with simple model calculations.


Assuntos
Físico-Química/métodos , Polímeros , Actinas/química , Biofísica/métodos , Biopolímeros , Eletrólitos , Íons , Modelos Moleculares , Espalhamento de Radiação , Eletricidade Estática , Raios X
6.
Phys Rev Lett ; 96(17): 177801, 2006 May 05.
Artigo em Inglês | MEDLINE | ID: mdl-16712331

RESUMO

We investigate the formation of ringlike deposits in drying drops of DNA. In analogy with the colloidal "coffee rings," DNA is transported to the perimeter by the capillary flow. At the droplet edge, however, DNA forms a lyotropic liquid crystal (LC) with concentric chain orientations to minimize the LC elastic energy. During the final stages of drying, the contact line retracts, and the radial stress causes undulations at the rim that propagate inward through the LC and form a periodic zigzag structure. We examine the phenomenon in terms of a simple model based on LC elasticity.


Assuntos
DNA/química , Simulação por Computador , Cristalização , Elasticidade , Conformação de Ácido Nucleico , Transição de Fase , Propriedades de Superfície , Fatores de Tempo
7.
Phys Rev Lett ; 91(2): 028301, 2003 Jul 11.
Artigo em Inglês | MEDLINE | ID: mdl-12906514

RESUMO

It is known empirically that multivalent ions generate attractions between like-charged polyelectrolytes, with different valence requirements for different systems. How multivalent must an ion be before it can condense a given polyelectrolyte? Using charge-tunable M13 virus rods and a family of artificial homologous "dumbbell" divalent ions of different sizes, we have constructed a multivalent ion-polyelectrolyte phase diagram, and find an experimentally motivated general criterion for like-charged attraction based on the ion valence, ion size, and the Gouy-Chapman length.


Assuntos
Bacteriófago M13/química , Eletrólitos/química , Ânions/química , Cátions Bivalentes/química , Concentração de Íons de Hidrogênio , Espalhamento de Radiação , Eletricidade Estática , Difração de Raios X , Raios X
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