858 resultados para panel estimates
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We discuss the optimality in L2 of a variant of the Incomplete Discontinuous Galerkin Interior Penalty method (IIPG) for second order linear elliptic problems. We prove optimal estimate, in two and three dimensions, for the lowest order case under suitable regularity assumptions on the data and on the mesh. We also provide numerical evidence, in one dimension, of the necessity of the regularity assumptions.
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Introduction: Many therapeutic decisions in the management of fistulizing and fibrostenotic Crohn's disease (CD) have to be taken without the benefit of strong scientific evidence. For this reason, explicit appropriateness criteria for CD fistula and stenosis treatment were developed by a multidisciplinary European expert panel in 2004 with the aim of making them easily available on the Internet and thus allowing individual case scenario evaluation; these criteria were updated in 2007. Methods: Twelve international experts convened in Geneva, Switzerland in December 2007. Explicit clinical scenarios, corresponding to real daily practice, were rated on a 9-point scale based on evidence from the published literature and panelists' own expertise. Median ratings were stratified into three categories: appropriate (7-9), uncertain (4-6) and inappropriate (1-3). Results: Overall, panelists rated 60 indications pertaining to fistulas. Antibiotics, azathioprine/6-mercaptopurine and conservative surgery are the mainstay of therapy for simple and complex fistulas. In the event of previous failure of azathioprine/6-mercaptopurine therapy, methotrexate and infliximab were considered appropriate for complex fistulas. The panel also rated 72 indications related to the management of fibrostenotic CD. The experts considered balloon dilation, if the stricture was endoscopically accessible, stricturoplasty and bowel resection to be appropriate for small bowel fibrostenotic Crohn's disease, and balloon dilation and bowel resection appropriate for fibrostenotic colonic disease. In the presence of an ileocolonic or ileorectal anastomotic stricture of <7 cm, endoscopic balloon dilation, and bowel resection were considered appropriate. Conclusion: Antibiotics, azathioprine/6-mercaptopurine, and conservative surgery are the mainstay of therapy for fistulizing Crohn's disease. Infliximab is a therapeutic option in patients without prior response to immunosuppressant therapy. In fibrostenotic Crohn's disease, endoscopic balloon dilation, if feasible, or surgical therapy should be considered. These expert recommendations are available online (www.epact.ch). Prospective evaluation is now needed to test the validity of these appropriateness criteria in clinical practice. (C) 2009 European Crohn's and Colitis Organisation. Published by Elsevier B.V. All rights reserved.
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We use panel data from the U. S. Health and Retirement Study, 1992-2002, to estimate the effect of self-assessed health limitations on the active labor market participation of older men. Self-assessments of health are likely to be endogenous to labor supply due to justification bias and individual-specific heterogeneity in subjective evaluations. We address both concerns. We propose a semiparametric binary choice procedure that incorporates nonadditive correlated individual-specific effects. Our estimation strategy identifies and estimates the average partial effects of health and functioning on labor market participation. The results indicate that poor health plays a major role in labor market exit decisions.
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This study examines the importance of change in characteristics and circumstances ofhouseholds and household members for contact and cooperation patterns. The literaturesuggests that there might be an underrepresentation of change in panel studies, becauserespondents facing more changes would be more likely to drop out. We approach this problemby analysing whether previous changes are predictive of later attrition or temporary drop-out,using eleven waves of the Swiss Household Panel (1999-2009). Our analyses supportprevious findings to some extent. Changes in household composition, employment status andsocial involvement as well as moving are associated mainly with attrition and less withtemporary drop-out. These changes affect obtaining cooperation rather than obtaining contact,and tend to increase attrition.
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Percutaneous transluminal renal angioplasty (PTRA) is an invasive technique that is costly and involves the risk of complications and renal failure. The ability of PTRA to reduce the administration of antihypertensive drugs has been demonstrated. A potentially greater benefit, which nevertheless remains to be proven, is the deferral of the need for chronic dialysis. The aim of the study (ANPARIA) was to assess the appropriateness of PTRA to impact on the evolution of renal function. A standardized expert panel method was used to assess the appropriateness of medical treatment alone or medical treatment with revascularization in various clinical situations. The choice of revascularization by either PTRA or surgery was examined for each clinical situation. Analysis was based on a detailed literature review and on systematically elicited expert opinion, which were obtained during a two-round modified Delphi process. The study provides detailed responses on the appropriateness of PTRA for 1848 distinct clinical scenarios. Depending on the major clinical presentation, appropriateness of revascularization varied from 32% to 75% for individual scenarios (overal 48%). Uncertainty as to revascularization was 41% overall. When revascularization was appropriate, PTRA was favored over surgery in 94% of the scenarios, except in certain cases of aortic atheroma where sugery was the preferred choice. Kidney size [7 cm, absence of coexisting disease, acute renal failure, a high degree of stenosis (C70%), and absence of multiple arteries were identified as predictive variables of favorable appropriateness ratings. Situations such as cardiac failure with pulmonary edema or acute thrombosis of the renal artery were defined as indications for PTRA. This study identified clinical situations in which PTRA or surgery are appropriate for renal artery disease. We built a decision tree which can be used via Internet: the ANPARIA software (http://www.chu-clermontferrand.fr/anparia/). In numerous clinical situations uncertainty remains as to whether PTRA prevents deterioration of renal function.
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BACKGROUND: The use of the family history method is recommended in family studies as a type of proxy interview of non-participating relatives. However, using different sources of information can result in bias as direct interviews may provide a higher likelihood of assigning diagnoses than family history reports. The aims of the present study were to: 1) compare diagnoses for threshold and subthreshold mood syndromes from interviews to those relying on information from relatives; 2) test the appropriateness of lowering the diagnostic threshold and combining multiple reports from the family history method to obtain comparable prevalence estimates to the interviews; 3) identify factors that influence the likelihood of agreement and reporting of disorders by informants. METHODS: Within a family study, 1621 informant-index subject pairs were identified. DSM-5 diagnoses from direct interviews of index subjects were compared to those derived from family history information provided by their first-degree relatives. RESULTS: 1) Inter-informant agreement was acceptable for Mania, but low for all other mood syndromes. 2) Except for Mania and subthreshold depression, the family history method provided significantly lower prevalence estimates. The gap improved for all other syndromes after lowering the threshold of the family history method. 3) Individuals who had a history of depression themselves were more likely to report depression in their relatives. LIMITATIONS: Low proportion of affected individuals for manic syndromes and lack of independence of data. CONCLUSIONS: The higher likelihood of reporting disorders by affected informants entails the risk of overestimation of the size of familial aggregation of depression.
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INTRODUCTION: The development of novel therapies and the increasing number of trials testing management strategies for luminal Crohn's disease (CD) have not filled all the gaps in our knowledge. Thus, in clinical practice, many decisions for CD patients need to be taken without high quality evidence. For this reason, a multidisciplinary European expert panel followed the RAND method to develop explicit criteria for the management of individual patients with active, steroid-dependent (ST-D) and steroid-refractory (ST-R) CD. AIMS & METHODS: Twelve international experts convened in Geneva, Switzerland in December 2007, to rate explicit clinical scenarios, corresponding to real daily practice, on a 9-point scale according to the literature evidence and their own expertise. Median ratings were stratified into three categories: appropriate (7-9), uncertain (4-6) and inappropriate (1-3). RESULTS: Overall, panelists rated 296 indications pertaining to mild-to-moderate, severe, ST-D, and ST-R CD. In anti-TNF naïve patients, budesonide and prednisone were found appropriate for mild-moderate CD, and infliximab (IFX) when those had previously failed or had not been tolerated. In patients with prior success with IFX, this drug with or without co-administration of a thiopurine analog was favored. Other anti-TNFs were appropriate in case of intolerance or resistance to IFX. High doses steroids, IFX or adalimumab were appropriate in severe active CD. Among 105 indications for ST-D or ST-R disease, the panel considered appropriate the thiopurine analogs, methotrexate, IFX, adalimumab and surgery for limited resection, depending on the outcome of prior therapies. Anti-TNFs were generally considered appropriate in ST-R. CONCLUSION: Steroids, including budesonide for mild-to-moderate CD, remain first-line therapies in active luminal CD. Anti-TNFs, in particular IFX with respect to the amount of available evidence, remain second-line for most indications. Thiopurine analogs are preferred to anti-TNFs when steroids are not appropriate, except when anti-TNFs were previously successful. These recommendations are available online (www.epact.ch). A prospective evaluation of these criteria in a large database in Switzerland in underway to validate these criteria.
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We study the equidistribution of Fekete points in a compact complex manifold. These are extremal point configurations defined through sections of powers of a positive line bundle. Their equidistribution is a known result. The novelty of our approach is that we relate them to the problem of sampling and interpolation on line bundles, which allows us to estimate the equidistribution of the Fekete points quantitatively. In particular we estimate the Kantorovich-Wasserstein distance of the Fekete points to its limiting measure. The sampling and interpolation arrays on line bundles are a subject of independent interest, and we provide necessary density conditions through the classical approach of Landau, that in this context measures the local dimension of the space of sections of the line bundle. We obtain a complete geometric characterization of sampling and interpolation arrays in the case of compact manifolds of dimension one, and we prove that there are no arrays of both sampling and interpolation in the more general setting of semipositive line bundles.
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Using a panel of 48 provinces for four years we empirically analyze a series of temporary policies aimed at curbing fuel consumption implemented in Spain between March and June 2011. The first policy was a reduction in the speed limit in highways. The second policy was an increase in the biofuel content of fuels used in the transport sector. The third measure was a reduction of 5% in commuting and regional train fares that resulted in two major metropolitan areas reducing their overall fare for public transit. The results indicate that the speed limit reduction in highways reduced gasoline consumption by between 2% and 3%, while an increase in the biofuel content of gasoline increased this consumption. This last result is consistent with experimental evidence that indicates that mileage per liter falls with an increase in the biofuel content in gasolines. As for the reduction in transit fares, we do not find a significant effect for this policy. However, in specifications including the urban transit fare for the major cities in each province the estimated cross-price elasticity of the demand for gasoline -used as a proxy for car use- with respect to the price of transit is within the range reported in the literature. This is important since one of the main eficiency justification for subsidizing public transit rests on the positive value of this parameter and most of the estimates reported in the literature are quite dated.
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Introduction Many therapeutic decisions in the management of fistulizing and fibrostenotic Crohn's disease (CD) have to be taken without the benefit of strong scientific evidence. For this reason, explicit appropriateness criteria for CD fistula and stenosis treatment were developed by a multidisciplinary European expert panel in 2004 with the aim of making them easily available on the Internet and thus allowing individual case scenario evaluation; these criteria were updated in 2007. Methods Twelve international experts convened in Geneva, Switzerland in December 2007. Explicit clinical scenarios, corresponding to real daily practice, were rated on a 9-point scale based on evidence from the published literature and panelists' own expertise. Median ratings were stratified into three categories: appropriate (7-9), uncertain (4-6) and inappropriate (1-3). Results Overall, panelists rated 60 indications pertaining to fistulas. Antibiotics, azathioprine/6-mercaptopurine and conservative surgery are the mainstay of therapy for simple and complex fistulas. In the event of previous failure of azathioprine/6-mercaptopurine therapy, methotrexate and infliximab were considered appropriate for complex fistulas. The panel also rated 72 indications related to the management of fibrostenotic CD. The experts considered balloon dilation, if the stricture was endoscopically accessible, stricturoplasty and bowel resection to be appropriate for small bowel fibrostenotic Crohn's disease, and balloon dilation and bowel resection appropriate for fibrostenotic colonic disease. In the presence of an ileocolonic or ileorectal anastomotic stricture of <7 cm, endoscopic balloon dilation, and bowel resection were considered appropriate. Conclusion Antibiotics, azathioprine/6-mercaptopurine, and conservative surgery are the mainstay of therapy for fistulizing Crohn's disease. Infliximab is a therapeutic option in patients without prior response to immunosuppressant therapy. In fibrostenotic Crohn's disease, endoscopic balloon dilation, if feasible, or surgical therapy should be considered. These expert recommendations are available online (www.epact.ch). Prospective evaluation is now needed to test the validity of these appropriateness criteria in clinical practice.
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Optimal robust M-estimates of a multidimensional parameter are described using Hampel's infinitesimal approach. The optimal estimates are derived by minimizing a measure of efficiency under the model, subject to a bounded measure of infinitesimal robustness. To this purpose we define measures of efficiency and infinitesimal sensitivity based on the Hellinger distance.We show that these two measures coincide with similar ones defined by Yohai using the Kullback-Leibler divergence, and therefore the corresponding optimal estimates coincide too.We also give an example where we fit a negative binomial distribution to a real dataset of "days of stay in hospital" using the optimal robust estimates.
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We analyze whether the interviewers' political opinions have an influence on those of the respondents. The research uses data from a panel survey in which interviewers are randomly assigned to respondents. The results show that the respondents express significantly similar opinions to those of the interviewers in all questions considered. Multilevel models show that more educated respondents are affected to a slightly higher extent and that the interviewer's experience is also a factor. There is no difference between different respondent subgroups or when both interviewers and respondents share the same socio-demographic characteristics. While there is no evidence for respondents wanting to please the interviewers, the hypothesis of socially desirable behavior can indeed be confirmed.
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To constrain deformation temperatures of mantle shear zones, we studied a strike-slip shear zone (Hilti massif, Semail ophiolite, Oman) and focused on the interaction between microstructural mechanisms and chemical equilibration processes. Quantitative microfabric analysis on harzburgites with different deformation intensity (porphyroclastic tectonite, mylonite, and ultramylonite) was combined with orthopyroxene geothermometry. The average grain size of all phases decreases with decreasing shear zone thickness. Dynamic recrystallization of porphyroclasts in combination with dissolution-precipitation and nucleation result in small-sized, chemically equilibrated pyroxenes. The composition of orthopyroxene was used to calculate deformation temperatures. In the case of the porphyroclastic tectonites, the chemical composition of orthopyroxene has been reset by diffusion yielding temperature estimates of 880-900 degrees C. The mylonites were deformed by dislocation creep of olivine and show a broad range of calculated temperatures, which result from a combination of grain size reduction and inheritance of equilibrium compositions from earlier high-temperature events and diffusion. In mylonites, diffusion profiles combined with geothermometry and grain size analysis indicate a mylonitic deformation temperature of 800-900 degrees C possibly followed by diffusion. In ultramylonites, the smallest grains (<30 mu m) reveal equilibration at temperatures of similar to 700 degrees C during the last stages of ductile deformation, which was dominated by diffusion creep of olivine. Our results provide a crucial link between temperature and evolution of microstructures from dislocation creep to diffusion creep in mantle shear zones.
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Electronic coupling Vda is one of the key parameters that determine the rate of charge transfer through DNA. While there have been several computational studies of Vda for hole transfer, estimates of electronic couplings for excess electron transfer (ET) in DNA remain unavailable. In the paper, an efficient strategy is established for calculating the ET matrix elements between base pairs in a π stack. Two approaches are considered. First, we employ the diabatic-state (DS) method in which donor and acceptor are represented with radical anions of the canonical base pairs adenine-thymine (AT) and guanine-cytosine (GC). In this approach, similar values of Vda are obtained with the standard 6-31 G* and extended 6-31++ G* basis sets. Second, the electronic couplings are derived from lowest unoccupied molecular orbitals (LUMOs) of neutral systems by using the generalized Mulliken-Hush or fragment charge methods. Because the radical-anion states of AT and GC are well reproduced by LUMOs of the neutral base pairs calculated without diffuse functions, the estimated values of Vda are in good agreement with the couplings obtained for radical-anion states using the DS method. However, when the calculation of a neutral stack is carried out with diffuse functions, LUMOs of the system exhibit the dipole-bound character and cannot be used for estimating electronic couplings. Our calculations suggest that the ET matrix elements Vda for models containing intrastrand thymine and cytosine bases are essentially larger than the couplings in complexes with interstrand pyrimidine bases. The matrix elements for excess electron transfer are found to be considerably smaller than the corresponding values for hole transfer and to be very responsive to structural changes in a DNA stack