In magnetic resonance imaging, precise measurements of longitudinal relaxation time (T1) is crucial to acquire useful information that is applicable to numerous clinical and neuroscience applications. In this work, we investigated the precision of T1 relaxation time as measured using the variable flip angle method with emphasis on the noise propagated from radiofrequency transmit field ([Formul...

Traditional portfolio optimization has been often criticized since it does not account for estimation risk. Theoretical considerations indicate that estimation risk is mainly driven by the parameter uncertainty regarding the expected asset returns rather than their variances and covariances. This is also demonstrated by several numerical studies. The global minimum variance portfolio has been a...

test day records of first lactation holstein cows from 1996 to 2008 were obtained from animal breeding center of iran and used in this research. data consisted of 872125 test-day milk records of 95816 cows from 59 herds. (co)variance components and genetic parameters were estimated using random regression model via gibbs sampling method. two order legendre polynomials and third coefficient of w...

the objective of this study was to estimate variance components, genetic and phenotypic trends for somatic cell score. dataset that collected by the animal breeding center of iran was used in this study. data file included 850,729 test day records of somatic cell counts (scc)  on 32,955 cows from lactations one to four, in 472 herds, gathered from years 2002 to 2013 in iran. a test day repeatab...

In this paper, an estimation of the Gaussian noise variance based on observed (measured) maximums of subsets of samples is given. Circumstances of the measurement environment being limited, only maximums of subsets of samples are available and the non-constant variance of the Gaussian noise can be estimated. In the case of power line noise, the variance of the zero mean Gaussian noise is a peri...

The objective of this study was to assess variance components and genetic parameters for fat and protein content in Tsigai sheep using multivariate animal models in which fat and protein content in individual months of lactation were treated as different traits, and univariate models in which fat and protein content were treated as repeated measures of the same traits. Test day measurements wer...

Existing studies of the effects of college quality on earnings typically rely on a single proxy variable for college quality. This study questions the wisdom of this approach given that a single proxy likely measures college quality with substantial error. We begin by considering the parameter of interest and its relation to the parameter estimated in the literature; this analysis reveals the p...

The recent article about estimated glomerular filtration rate (GFR) by Levey and colleagues (1) is remarkable. The authors suggest that the new equation may still have some bias and especially may have less precision in patients with GFRs greater than 60 mL/min per 1.73 m 2 . This is even more important if the GFR is greater than 90 mL/min per 1.73 m 2 . In the paper's Methods section, Levey an...

A new method of stochastically estimating the low-lying effects of quark propagation is proposed which allows accurate determinations of temporal correlations of single-hadron and multihadron operators in lattice QCD. The method is well suited for calculations in large volumes. Contributions involving quark propagation connecting hadron sink operators at the same final time can be handled in a ...