Univariate Parameters Research Articles

Temporal linear mode complexity as a surrogate measure of the effect of remifentanil on the central nervous system in healthy volunteers

• Remifentanil, an intravenous ultra short-acting opioid, depresses central nervous system activity with an increase in the delta band power, and causes beta activation after discontinuation, resulting in a rebound of the processed electroencephalographic parameters, including 95% spectral edge frequency, the canonical univariate parameter and electroencephalographic approximate entropy. • A sigmoid Emax model, in which the highest predicted values of processed electroencephalographic parameters are restricted to the baseline value, cannot describe a rebound of these parameters. • Electroencephalographic approximate entropy correlated well with the remifentanil blood concentration and demonstrated high baseline stability. • A combined effect and tolerance model effectively characterized the time course of the remifentanil effect on the central nervous system, including the rebound which occurred during recovery from the remifentanil effect. • Temporal linear mode complexity was comparable with approximate entropy as a univariate electroencephalographic descriptor of the effect of remifentanil on the central nervous system. AIMS Previously, electroencephalographic approximate entropy (ApEn) effectively described both depression of central nervous system (CNS) activity and rebound during and after remifentanil infusion. ApEn is heavily dependent on the record length. Linear mode complexity, which is algorithmatically independent of the record length, was investigated to characterize the effect of remifentanil on the CNS using the combined effect and tolerance, feedback and sigmoid E(max) models. METHODS The remifentanil blood concentrations and electroencephalographic data obtained in our previous study were used. With the recording of the electroencephalogram, remifentanil was infused at a rate of 1, 2, 3, 4, 5, 6, 7 or 8 µg kg(-1) min(-1) for 15-20 min. The areas below (AUC(effect) ) or above (AAC(rebound) ) the effect vs. time curve of temporal linear mode complexity (TLMC) and ApEn were calculated to quantitate the decrease of the CNS activity and rebound. The coefficients of variation (CV) of median baseline (E(0)), maximal (E(max)), and individual median E(0) minus E(max) values of TLMC were compared with those of ApEn. The concentration-TLMC relationship was characterized by population analysis using non-linear mixed effects modelling. Median AUC(effect) and AAC(rebound) were 1016 and 5.3 (TLMC), 787 and 4.5 (ApEn). The CVs of individual median E(0) minus E(max) were 35.6, 32.5% (TLMC, ApEn). The combined effect and tolerance model demonstrated the lowest Akaike information criteria value and the highest positive predictive value of rebound in tolerance. The combined effect and tolerance model effectively characterized the time course of TLMC as a surrogate measure of the effect of remifentanil on the CNS.

Weighted scores method for regression models with dependent data

There are copula-based statistical models in the literature for regression with dependent data such as clustered and longitudinal overdispersed counts, for which parameter estimation and inference are straightforward. For situations where the main interest is in the regression and other univariate parameters and not the dependence, we propose a "weighted scores method", which is based on weighting score functions of the univariate margins. The weight matrices are obtained initially fitting a discretized multivariate normal distribution, which admits a wide range of dependence. The general methodology is applied to negative binomial regression models. Asymptotic and small-sample efficiency calculations show that our method is robust and nearly as efficient as maximum likelihood for fully specified copula models. An illustrative example is given to show the use of our weighted scores method to analyze utilization of health care based on family characteristics.

Percentile-based Empirical Distribution Function Estimates for Performance Evaluation of Healthcare Providers.

Hierarchical models are widely-used to characterize the performance of individual healthcare providers. However, little attention has been devoted to system-wide performance evaluations, the goals of which include identifying extreme (e.g., top 10%) provider performance and developing statistical benchmarks to define high-quality care. Obtaining optimal estimates of these quantities requires estimating the empirical distribution function (EDF) of provider-specific parameters that generate the dataset under consideration. However, the difficulty of obtaining uncertainty bounds for a square-error loss minimizing EDF estimate has hindered its use in system-wide performance evaluations. We therefore develop and study a percentile-based EDF estimate for univariate provider-specific parameters. We compute order statistics of samples drawn from the posterior distribution of provider-specific parameters to obtain relevant uncertainty assessments of an EDF estimate and its features, such as thresholds and percentiles. We apply our method to data from the Medicare End Stage Renal Disease (ESRD) Program, a health insurance program for people with irreversible kidney failure. We highlight the risk of misclassifying providers as exceptionally good or poor performers when uncertainty in statistical benchmark estimates is ignored. Given the high stakes of performance evaluations, statistical benchmarks should be accompanied by precision estimates.

Quel bilan d’extension faut-il faire pour les carcinomes indifferencies du nasopharynx ?

Introduction: Nasopharyngeal carcinoma prognosis is often correlated with its local extension but especially lymphatic node and metastatic.The aimof our work was to study sensitivity and the specificity of clinical and paraclinic explorations in the initial assessmentPatients and methods : It .s about a retrospective study of 366 patients having nasopharyngeal carcinoma, diagnosed over eleven years period between 1993 and 2003 in Sfax hospital. Into pretherapeutic, all the patients had a complementary assessment including:- Nasopharyngeal tomodensitometry (TDM), in all the cases, extended to the cervical area in 112 cases and a magnetic resonnance Imagery (MRI) of the nasopharynx and cerebral in 18 cases.- Metastatic assessment: comprising systematically a chest radiography, an abdominal ultrasonography and an osseous scintiscanning. The statistical study comprised a descriptive study and an analytical study.Results : The metastasis diagnosis was retained in 39 cases (10,7%): osseous in 82%, hepatic in 23% and pulmonary in 12,8% of the cases. The tumour was associated to lymph node N3 in 25 cases (64%). At univariate study, we retained the presence of significant difference between the groups of the metastatic and lack metastatic patients for : the male sex, reason for consultation (cervical node, rhinologic signs and otologic signs) and cervical node at the examination.The multivariate analysis for all the factors was without interest. We choose the parameters according to the result of the univariate study, the literature and parameters' found among all patients with discovered CNP. It comes out from this study that the following elements are providers of metastases: age between 40 and 45years, male sex and cervical node N3a stage.Discussion : The assessment of extension is not standardized for all the authors. Indeed, for the study of the pulmonary extension (AJCC)/ (UICC) recommends the systematic practice of the chest radiography. For (NCCN), the practice of chest radiography is only for patients classified at the stage 2 and 3 in WHO classification. For KUMAR, LEUNG and our results, it is recommended systematically to practice the chest radiography . This radiography would be supplemented by a thoracic tomodensitometry with the least suspect lesion. For the hepatic assessment, some recommend the systematic practice of abdominal echography for the advanced nodestages (N3). For others, it will be indicated only for the symptomatic patients. For (AJCC)/ (UICC) abdominal echography is systematic.For the osseous assessment, KRAIPHIBUL recommends the practice of the osseous scintiscanning only for patients having signs of osseous call but LEUNG and SHAM recommend the practice of the osseous scintiscanning only for the patients having cervical node N3.Key words: Nasopharyngeal carcinoma/ extension assessment/ metastasis.

Multivariate Analysis of Morphometric Characteristics to Evaluate Risk Factors for Cranial Cruciate Ligament Deficiency in Labrador Retrievers

To determine the combination of conformation characteristics of the pelvic limbs of Labrador Retrievers that best discriminates between limb at risk to develop cranial cruciate ligament (CCL) disease and limbs at low risk using radiographs, computerized tomography (CT) images, and dual-energy X-ray absorptiometry (DEXA). Cross-sectional clinical study. Twelve clinically normal and 9 unilaterally CCL-deficient Labrador Retrievers. The pelvic limbs of normal dogs were considered as non-predisposed to CCL disease and the contralateral limbs of CCL-deficient dogs as predisposed. Conformation variables, obtained from femur and tibial radiographs, pelvic limb CT images and DEXA studies, of predisposed pelvic limbs were compared with the conformation variables from pelvic limbs of the low-risk group. An ROC curve analysis was used to assess the discriminating properties of conformation variables for several combinations. We determined that a combination of tibial plateau angle (TPA) and femoral anteversion angle (FAA) measured on radiographs was optimal for discriminating predisposed and non-predisposed limbs for CCL disease in Labrador Retrievers. Assessing predisposition to CCL disease with a combination of conformational measurements is better than using univariate parameters. In the future, TPA and FAA may be used to screen dogs suspected of being susceptible to CCL disease.

Free flap reconstruction for osteoradionecrosis of the jaws—Outcomes and predictive factors for success

The purpose of this study was to determine factors to predict the success of free flap surgery in the treatment of osteoradionecrosis (ORN). Univariate analysis of overall and flap complications was performed. The effect of time to ORN, and the time interval between ORN to reconstruction was evaluated. Fifty-five flaps on 53 patients for ORN were done with a 90% resolution rate. Univariate parameter analysis was significant for infield mandibulotomy. An increased time interval from radiation therapy (XRT) to ORN development significantly predicted for flap-specific complications and flap loss (p < .05). Increased time from ORN diagnosis to flap surgery resulted in greater length of bone involvement (p = .01). Anastomotic complications occurred in 13 cases resulting in 7 complete flap losses. An increased risk of complication was encountered with greater time from XRT to ORN. Thus, in patients developing ORN long after treatment, surgery should be accordingly more aggressive.

Computed tomography pelvimetry as a predictor of technical difficulty in total mesorectal excision

To investigate the limiting effect of pelvic diameters on the technical difficulty of total mesorectal excision(TME) for rectal cancer by computed tomography pelvimetry. From January 2009 to January 2011, 69 patients with rectal cancer underwent TME in the Department of Proctology at the Changhai Hospital in Shanghai. There were 55 males and 14 females. Using three dimensional reconstruction software, pelvic dimensions of rectal cancer patients were measured based on pelvic MDCT thin-slice computed tomography. All the patients were measured for 15 pelvic parameters, including the length of pelvic inlet, the length of pubic symphysis, the interspinous distance, the distance from sacral promontory to tip of coccyx, etc. All the procedures were open surgery, including anterior resection(n=19), low anterior resection and ileostomy(n=29) and abdominal perineal resection(n=21). Duration of the operation and blood loss at surgery were recorded as evaluation indicators of the technical difficulty of total mesorectal excision. By univariate analysis significant pelvic parameters were selected. Multiple regression analysis was used to investigate the relationship between pelvic parameters and blood loss or duration of operation. The mean operative time was(139.9±32.4) min and the mean intraoperative blood loss was (228.8±150.6) ml. Multivariate analysis showed that the interspinous distance, the length of pelvic inlet, the distance from sacral promontory to the tip of coccyx were the main factors affecting the operation time, and that the length of pubic symphysis and the distance from sacral promontory to the tip of coccyx were the main factors affecting the amount of blood loss (all P<0.05). Among the 3 procedures, the multivariate analysis for low anterior resection appeared to be most valuable, in which operative time was associated with the distance from sacral promontory to the tip of coccyx and the interspinous distance (adjusted coefficient of determination of the regression equation, Rc(2)=0.460, P=0.003). Factors associated with intraoperative blood loss were the length of pelvic inlet, the distance from sacral promontory to the tip of coccyx, and the sacrum-pubis angle(Rc(2)=0.358, P=0.022). Comprehensive analysis of the measurement parameters showed that the ratio between the length of pelvic inlet and the distance from sacral promontory to the tip of coccyx was associated with the operative time and blood loss. This ratio was significantly higher in female patients than that in males. In females with a ratio greater than 1, the operative time was significantly shorter(P=0.050), and the intraoperative blood loss was significantly less in males with a ratio greater than 0.9(P=0.021). Operative time and intraoperative blood loss for total mesorectal excision are more favorable in patients with a wide and shadow pelvis. Surgical difficulty is increased in deep and narrow pelvis or those with major sacrum curvature. The difficulty of total mesorectal excision procedure can be predicted by measuring the length of pelvic inlet and the distance from sacral promontory to the tip of coccyx.

Quantized-TT-Cayley Transform for Computing the Dynamics and the Spectrum of High-Dimensional Hamiltonians

Abstract In the present paper, we propose and analyse a class of tensor methods for the efficient numerical computation of the dynamics and spectrum of high-dimensional Hamiltonians. We focus on the complex-time evolution problems. We apply the quantized-TT (QTT) matrix product states type tensor approximation that allows to represent N-d tensors generated by the grid representation of d-dimensional functions and operators with log-volume complexity, O(d log N), where N is the univariate discretization parameter in space. Making use of the truncated Cayley transform method allows us to recursively separate the time and space variables and then introduce the efficient QTT representation of both the temporal and the spatial parts of the solution to the high-dimensional evolution equation. We prove the exponential convergence of the m-term time-space separation scheme and describe the efficient tensor-structured preconditioners for the arising system with multidimensional Hamiltonians. For the class of "analytic" and low QTT-rank input data, our method allows to compute the solution at a fixed point in time t=T&gt;0 with an asymptotic complexity of order O(d log N ln^q (1/ε)), where ε&gt;0 is the error bound and q is a fixed small number. The time-and-space separation method via the QTT-Cayley-transform enables us to construct a global m-term separable (x,t)-representation of the solution on a very fine time-space grid with complexity of order O(dm^4 log N_t log N), where N_t is the number of sampling points in time. The latter allows efficient energy spectrum calculations by FFT (or QTT-FFT) of the autocorrelation function computed on a sufficiently long time interval [0,T]. Moreover, we show that the spectrum of the Hamiltonian can also be represented by the poles of the t-Laplace transform of a solution. In particular, the approach can be an option to compute the dynamics and the spectrum in the time-dependent molecular Schrödinger equation.

Measuring core inflation in Italy comparing aggregate vs. disaggregate price data

This paper focuses on the core inflation measurement in Italy using univariate (national-level inflation) vs. multivariate (city-level inflation) models during the period 1970–2006. We derive algebraic expressions that allow comparison between the reduced form parameters of univariate and multivariate local level models in the context of contemporaneous and temporal aggregation. We illustrate the relevance of these theoretical results for the empirical analysis of time series. Using Italian data, we find that multivariate and univariate models extract similar core inflation measures when analyzing the moderate-low inflation period. In contrast, the two competing models yield different trends when modeling the Great Inflation period.

Molluscan assemblages in littoral soft bottoms of the Alboran Sea (Western Mediterranean Sea)

The structure of the molluscan assemblages inhabiting the subtidal bottoms off the west coast of Malaga province (southern Spain) and their relation to sediment characteristics were analysed with both univariate and multivariate parameters. Five significantly different molluscan assemblages were identified and assigned to ‘sables fins bien calibrés’ (SFBC, well sorted fine sands); ‘détritique côtier’ (DC, coastal bioclastic sands); ‘détritique envasé’ (DE, muddy bioclastic sands); and ‘coralligène’ (CO, coralligenous) biocoenoses of Pérès and Picard classification. A total of 234 molluscan species were identified, with gastropods as the dominant group (135 species). An increase of diversity and evenness with depth has been observed, with the highest values for both indexes on a rocky outcrop, and the lowest in the shallower fine sand assemblage dominated by few species. The different molluscan assemblages inhabiting these sublittoral bottoms were conditioned by depth, percentage of gravel and percentage of clay. A large proportion of tropical West African species is found in the area, some of them reaching their distributional limit towards the Mediterranean Sea. The southern Iberian coasts, in the confluence of Atlantic and Mediterranean waters and between Africa and Europe, are therefore highlighted as one of the areas with highest molluscan species richness in Europe, and require a conservation policy in order to preserve this unique European biodiversity heritage.

Doppler in Fetal Heart Failure

Fetal echocardiography has progressed to be able to diagnose many forms of congenital heart disease (CHD) and to assess the prognosis of cardiac lesions based on their anatomy and presentation in utero. Fetal echocardiography is for pregnancies at risk of structural, functional, and rhythm-related fetal heart disease. Routine obstetrical ultrasound screening is critical in the prenatal detection of fetal heart disease/CHD. With or without CHD, fetal heart dysfunction defined as inadequate tissue perfusion may occur. Perinatal problems other than CHD can also be assessed, such as the effects of noncardiac malformations that affect hemodynamics, that is, twin-twin transfusion. Cardiac rhythm can affect cardiac function and outcome, and prenatal diagnosis can be lifesaving. A tool for the assessment of cardiac function is the Cardiovascular Profile Score that combines ultrasonic markers of fetal cardiovascular unwellness based on univariate parameters, which have been correlated with perinatal mortality. This "heart failure score" could potentially be used in much the same way as and in combination with the biophysical profile score. This study will present a summary of fetal Doppler and its place in the diagnosis and assessment of prognosis of fetal heart failure.

Estimation of effective parameters for a two-phase flow problem in non-Gaussian heterogeneous porous media

In this paper we discuss estimates of effective parameters for an upscaled model for buoyant counter flow of DNAPL and water in a closed box filled with heterogeneous porous material. The upscaling procedure is based on the assumption that the flow is dominated by capillary forces on the small scale and that the fluids are segregated. The upscaled model has the same form as the usual two-phase flow model with an effective capillary pressure function and an effective mobility function Λ. Effective parameters are then estimated in two different ways. Stochastic theory can be applied to calculate the effective parameters to first order in the parameter fluctuations. This approach does not take into account that different parameter ranges of the heterogeneous field may be connected or isolated, yielding very different macroscopic residual saturations. Therefore, the second estimate of effective parameters takes connectivity of parameter ranges into account. In this case, the univariate parameter distribution of the heterogeneous field and the values that mark connected materials are the only information about heterogeneity that is used. Effective parameters are then estimated using mean field theory (the Maxwell approach). The upscaled model and the estimation of effective parameters are applied to a numerical test case. Buoyant counter flow in heterogeneous parameter fields with different structures is simulated numerically and compared to the solutions of the quasi-1d upscaled model with differently estimated parameters. It is demonstrated that connectivity of the different parameter ranges is an important information that determines typical time scales for the flow process and the macroscopic residual saturation. Even simple estimates of effective parameters based on little information may capture the typical time scales, provided that information about connected parameter ranges is taken into account.

Community Structure and Spatial Patterns in Hard Coral Biodiversity in Selected Islands in the Gulf of Mannar, India

The major reefs of the Gulf of Mannar Biosphere Reserve extend from the Tuticorin group of islands (Long.78 0 9’E, Lat.8 0 48’N) to the Shingle Island (Long. 79 0 14’E, Lat.9 0 14’N) in Mandapam, India. These reefs are under increasing threats from anthropogenic interventions. In view of this, a comparative study was conducted to deduce the spatial patterns in the hard coral biodiversity and community structure of five islands of the Mandapam group. The islands studied are Shingle, Krusadai, Pullivasal, Manauli and Hare. Univariate community parameters, Shannon–Wiener diversity index (H’e), Simpson diversity index, and Pielou’s evenness index were calculated for each reef in each sampling station. The highest and lowest percentage of live coral cover was recorded in the reefs of the Shingle (60.8%) and Pullivasal Islands (13.9%) respectively. Shannon index of diversity recorded maximum value in the reefs of Manauli Island (3.01) and the minimum in Pullivasal Island (1.8). Mortality indices were also derived for each island reef and the condition of the reefs was assigned as either good/sick. Relative abundance values were derived for each species and they were assigned Dominant/Abundant/ Common/Unc ommon/Rare species status. Conservation classes (CC’s) of 1,2,3 or 4 were assigned to reef sites dominated by massive and submassive corals (CC1), foliose or branching non Acropora corals (CC2), Acropora corals (CC3), or approximately equal mixes of these three end – members(CC4). Similarities between reefs were studied by Bray–Curtis similarity coefficients and maximum similarity was found between the Manauli and Hare Island reefs (56.47). The similarity matrix was subjected to ordination analysis. There was a distinct separation of reefs in the Pullivasal Island from other reefs in the MDS plot. SIMPER analysis enabled the authors to find out the species important in the community structure of each reef. From the present study it was concluded that certain coral reefs in the Gulf of Mannar ecosystem is on the threshold of degradation.

Temporal dynamics of gastropod fauna on subtidal sandy sediments of the Ensenada de Baiona (NW Iberian Peninsula)

The temporal variation of the gastropod fauna inhabiting sandy sediments of the Ensenada de Baiona (Galicia, Spain) was studied at three subtidal sites from February 1996 to February 1997 by means of quantitative sampling. A total of 5,463 individuals representing 51 gastropod species and 22 families were found. The family Pyramidellidae was the most diverse in number of species (11 species), followed by Rissoidae and Trochidae (4 species each). The dogwhelk, Nassarius reticulatus, and the rissoid snail, Rissoa parva, were the numerically dominant species at the three studied sites; those and other abundant species showed their greatest densities by the end of summer and the beginning of autumn. In general, univariate measures of the assemblage (number of species, abundance, diversity and evenness) showed variations through time; greater values were recorded between summer and autumn depending on the site. Multivariate analyses done on abundance data showed certain seasonality in the evolution of the assemblage as expected for shallow subtidal sandy sediments at temperate latitudes; those seasonal changes were mostly related to variations in abundance of numerically dominant species. Although the measured sedimentary variables did not show significant correlations with faunal univariate parameters, sediment heterogeneity due to the presence of mats of Zostera marina L. and shells of dead bivalves might explain the differences in composition of the gastropod assemblage among sampling sites.

Geostatistical Analysis for Spatially Referenced Roller-Integrated Compaction Measurements

An approach to quantify nonuniformity of compacted earth materials using spatially referenced roller-integrated compaction measurements and geostatistical analysis is discussed. Measurements from two detailed case studies are presented in which univariate statistical parameters are discussed and compared to geostatistical semivariogram modeling parameters and analysis. The univariate and geostatistical parameter values calculated from the roller-integrated measurements are also compared to traditional spot test acceptance criteria. Univariate statistical parameter values based on roller-integrated measurement values provide significantly more information than traditional point measurements, while geostatistics can be used to identify regions of noncompliance and prioritize areas for rework.

Genitourinary Fistula Experience in Sierra Leone: Review of 505 Cases

We reviewed cases of genitourinary fistula resulting from birth trauma in Sierra Leone to determine factors predictive of successful operative repair. A total of 505 operative repairs of genitourinary fistula were completed at 2 centers in Sierra Leone from 2004 to 2006. Statistical analysis of patient demographics, fistula characteristics, outcomes and surgical complications was performed. Primary repairs, defined as the first repair, accounted for 68% of repairs in the population with 92% classified as vesicovaginal fistula alone. Only 56% of women were deemed to have an intact urethra at presentation and 68% were diagnosed with moderate or severe fibrosis surrounding the fistula. On univariate analysis parameters that demonstrated significant differences with primary operative success were patient age at fistula occurrence (p = 0.0192), index pregnancy (p = 0.0061), location (p <0.0001), surface area (p <0.0001), urethral status (p <0.0001) and fibrosis (p <0.0001). On multivariate analysis the fistula parameter that correlated with successful repair was the extent of fibrosis (severe fibrosis OR 3.7). Genitourinary fistula as a result of prolonged obstructed labor is a cause of considerable morbidity in sub-Saharan Africa, including Sierra Leone. The most profound factor correlating with a positive operative outcome was the extent of fibrosis surrounding the fistula. These data are important to help predict the likelihood of successful repair and assist in selecting women for the appropriate surgical procedure.

Correction of axial chromatic aberrations in confocal Raman microspectroscopic measurements of a single microbial spore

Herein we describe a strategy for correcting the longitudinal or axial component of chromatic aberration in confocal Raman microspectroscopy. The method is based on measuring a vertical series of confocal Raman sections of samples by a high numerical aperture Raman microscope. Using the known characteristics of the wavelength-dependent focal shift of the optical system, the Raman intensities can be corrected to allow the rearrangement of Raman data from different focal planes. In the present study the computational correction routine was applied to an experimental data set of 4-dimensional (xyz spatial and the spectral dimension) confocal Raman spectra collected from single spores of Bacillus cereus. After correcting the axial component of the chromatic aberration, univariate and multivariate spectral parameters were obtained and used in the following for 3D segmentation and volume rendering on the basis of the structural and compositional information contained in the Raman spectra of the spore. Using univariate Raman intensities from defined functional group frequencies or k-means cluster membership values as a multivariate parameter for volume rendering, we demonstrate a high degree of correlation between confocal Raman microspectroscopy and the spores' morphology. In this paper we will also present cluster mean spectra which will be discussed in light of the presence of proteins and Ca-DPA, a calcium chelate of dipicolinic acid in the spore.

Estimating a weighted average of stratum‐specific parameters

This article investigates estimators of a weighted average of stratum-specific univariate parameters and compares them in terms of a design-based estimate of mean-squared error (MSE). The research is motivated by a stratified survey sample of Florida Medicaid beneficiaries, in which the parameters are population stratum means and the weights are known and determined by the population sampling frame. Assuming heterogeneous parameters, it is common to estimate the weighted average with the weighted sum of sample stratum means; under homogeneity, one ignores the known weights in favor of precision weighting. Adaptive estimators arise from random effects models for the parameters. We propose adaptive estimators motivated from these random effects models, but we compare their design-based performance. We further propose selecting the tuning parameter to minimize a design-based estimate of mean-squared error. This differs from the model-based approach of selecting the tuning parameter to accurately represent the heterogeneity of stratum means. Our design-based approach effectively downweights strata with small weights in the assessment of homogeneity, which can lead to a smaller MSE. We compare the standard random effects model with identically distributed parameters to a novel alternative, which models the variances of the parameters as inversely proportional to the known weights. We also present theoretical and computational details for estimators based on a general class of random effects models. The methods are applied to estimate average satisfaction with health plan and care among Florida beneficiaries just prior to Medicaid reform.

Some inequalities related to the Stam inequality

Zamir showed in 1998 that the Stam classical inequality for the Fisher information (about a location parameter) $$ 1/I(X + Y) \geqslant 1/I(X) + 1/I(Y) $$ for independent random variables X, Y is a simple corollary of basic properties of the Fisher information (monotonicity, additivity and a reparametrization formula). The idea of his proof works for a special case of a general (not necessarily location) parameter. Stam type inequalities are obtained for the Fisher information in a multivariate observation depending on a univariate location parameter and for the variance of the Pitman estimator of the latter.

The value of fractional and coronary flow reserve in predicting myocardial recovery in patients with previous myocardial infarction

The aim of the study was to evaluate the relation between fractional flow reserve (FFR) and simultaneously evaluated coronary flow reserve by thermodilution (CFRthermo), with the improvement of left ventricular (LV) function in patients with previous myocardial infarction (MI) undergoing percutaneous coronary intervention (PCI). Study population consisted of 46 patients (mean age 53 +/- 7 years; 36 male) with previous MI and significant coronary stenosis undergoing PCI of infarct-related coronary artery. In all patients, we evaluated FFR and CFRthermo by single pressure/thermo wire during maximal hyperaemia before and immediately after PCI. We performed echocardiographic assessment of LV ejection fraction before and 6 months after PCI. Dobutamine stress echocardiography test was also performed before PCI. LV functional improvement was observed in 33/46 (72%) of patients. In patients with LV functional recovery in comparison with patients with no recovery, there was a significant difference in FFR before PCI (0.56 +/- 0.14 vs. 0.70 +/- 0.07, P < 0.001), improvement of FFR (0.35 +/- 0.14 vs. 0.21 +/- 0.07, P < 0.001), improvement of CFRthermo (1.3 +/- 0.6 vs. 0.5 +/- 0.3, P < 0.001), and CFRthermo after PCI (2.6 +/- 0.7 vs. 2.0 +/- 0.4, P < 0.001). When only parameters evaluated before PCI were taken into account, FFR before angioplasty (P = 0.001) and dobutamine-assessed viability (P = 0.006) were the most significant multivariate predictors of myocardial recovery. When all significant univariate parameters were evaluated, the most significant independent predictors for improvement in myocardial function were the improvement of CFRthermo during angioplasty (P < 0.001) and FFR before angioplasty (P = 0.002). Simultaneous evaluation of FFR and CFRthermo provide significant complementary data on the improvement in myocardial function in patients with previous MI. However, the evaluation of FFR before angioplasty identifies viable myocardium that may recover following revascularization and may be used as an alternative to non-invasive testing.