Estimating stellar oscillation-related parameters and their uncertainties with the moment method

The moment method is a well known mode identification technique in asteroseismology (where `mode' is to be understood in an astronomical rather than in a statistical sense), which uses a time series of the first 3 moments of a spectral line to estimate the discrete oscillation mode parameters l and m. The method, contrary to many other mode identification techniques, also provides estimates of other important continuous parameters such as the inclination angle alpha, and the rotational velocity v_e. We developed a statistical formalism for the moment method based on so-called generalized estimating equations (GEE). This formalism allows the estimation of the uncertainty of the continuous parameters taking into account that the different moments of a line profile are correlated and that the uncertainty of the observed moments also depends on the model parameters. Furthermore, we set up a procedure to take into account the mode uncertainty, i.e., the fact that often several modes (l,m) can adequately describe the data. We also introduce a new lack of fit function which works at least as well as a previous discriminant function, and which in addition allows us to identify the sign of the azimuthal order m. We applied our method to the star HD181558, using several numerical methods, from which we learned that numerically solving the estimating equations is an intensive task. We report on the numerical results, from which we gain insight in the statistical uncertainties of the physical parameters involved in the moment method.Comment: The electronic online version from the publisher can be found at http://www.blackwell-synergy.com/doi/abs/10.1111/j.1467-9876.2005.00487.

Maximizing the Conditional Expected Reward for Reaching the Goal

The paper addresses the problem of computing maximal conditional expected accumulated rewards until reaching a target state (briefly called maximal conditional expectations) in finite-state Markov decision processes where the condition is given as a reachability constraint. Conditional expectations of this type can, e.g., stand for the maximal expected termination time of probabilistic programs with non-determinism, under the condition that the program eventually terminates, or for the worst-case expected penalty to be paid, assuming that at least three deadlines are missed. The main results of the paper are (i) a polynomial-time algorithm to check the finiteness of maximal conditional expectations, (ii) PSPACE-completeness for the threshold problem in acyclic Markov decision processes where the task is to check whether the maximal conditional expectation exceeds a given threshold, (iii) a pseudo-polynomial-time algorithm for the threshold problem in the general (cyclic) case, and (iv) an exponential-time algorithm for computing the maximal conditional expectation and an optimal scheduler.Comment: 103 pages, extended version with appendices of a paper accepted at TACAS 201

Adaptive Covariance Estimation with model selection

We provide in this paper a fully adaptive penalized procedure to select a covariance among a collection of models observing i.i.d replications of the process at fixed observation points. For this we generalize previous results of Bigot and al. and propose to use a data driven penalty to obtain an oracle inequality for the estimator. We prove that this method is an extension to the matricial regression model of the work by Baraud

Long-Term PIT and T-Bar Anchor Tag Retention Rates in Adult Muskellunge

Mark-recapture studies require knowledge of tag retention rates specific to tag types, fish species and size, and study duration. We determined the probability of tag loss for passive integrated transponder (PIT) tags implanted into dorsal musculature, T-bar anchor tags attached to dorsal pterygiophores, and loss of both tags in relation to years post-tagging for double-marked adult muskellunge Esox masquinongy over a 10 year period. We also used PIT tags as a benchmark to assess the interactive effects of fish length at tagging, sex, and years post-tagging on T-bar anchor tag loss rates. Only five instances of PIT tag loss were identified; the calculated probability of a fish losing its PIT tag was consistently \u3c 1.0% for up to 10 years post-tagging. The probability of T-bar anchor tag loss by muskellunge was related to the number of years post-tagging and total length of fish at tagging. T-bar anchor tag loss rate one year after tagging was 6.5%. Individuals \u3c 750 mm total length at tagging had anchor tag loss rates \u3c 10% for up to 6 years after tagging. However, the proportion of fish losing T-bar anchor tags steadily increased with increasing years post-tagging (~30% after 6 years) for larger muskellunge. Fish gender did not influence probability of T-bar anchor tag loss. Our results indicate that T-bar anchor tags are best suited for short-term applications (≤ 1 year duration) involving adult muskellunge. We recommend use of PIT tags for longer-term tagging studies, particularly for muskellunge \u3e 750 mm total length

Indications for pediatric hematopoietic stem cell transplantation: consensus presented at the First Meeting on Brazilian Hematopoietic Stem Cell Transplantation Guidelines - Brazilian Society of Bone Marrow Transplantation, Rio de Janeiro, 2009

The Brazilian Bone Marrow Transplant Society (SBTMO) held its First Meeting on Bone Marrow Transplant Guidelines in 2009. A working group of hematologists and oncologists with experience in pediatrics was formed to review evidence-based indications for pediatric transplants. Scientific publications were carefully assessed and, for each disease, the evidence for recommendation (from A to C) and the quality of the evidence (from 1 to 3) were defined. The recommendations include malignant and non-malignant hematological diseases, solid tumors, immunodeficiency, and storage diseases treated with hematopoietic stem cell transplants: either autologous or allogeneic from matched sibling donors or unrelated donors (adults or umbilical cord blood). Guidelines for reduced-intensity transplants, manipulated grafts or partially compatible donors were not included as there are no uniformly accepted recommendations. All indications are based on the best current knowledge which may change over time. Thus, this review should not be directly applied to patient care without taking into account the disease, donor and patient characteristics. Additionally, this paper should not be used as a document to limit patient access to transplant if correctly indicated. In this review we also point out differences between transplantation in adults and children and make some specific recommendations for pediatric transplants.A Sociedade Brasileira de Transplante de Medula (SBTMO) promoveu o I Encontro de Diretrizes do Transplante de Medula Óssea em 2009. Para revisão das indicações de transplante em Pediatria baseadas em evidências foi constituído grupo de trabalho com oncologistas e hematologistas com experiência em pediatria. Os artigos científicos foram cuidadosamente avaliados e, para cada doença, foram definidas as evidências para recomendação dos transplantes (de A a C) e a qualidade destas evidências (de 1 a 3). As recomendações incluem doenças hematológicas malignas e não malignas, tumores sólidos, imunodeficiências e doenças de depósito tratadas com transplantes de células-tronco hematopoéticas, quer autólogos, alogênicos de irmão HLA compatível ou não aparentados (doadores adultos ou sangue de cordão umbilical). Como não existem recomendações uniformemente aceitas em pediatria, não foram incluídas recomendações para transplantes de intensidade reduzida, com manipulação do enxerto e nem parcialmente compatíveis. É importante ressaltar que todas as indicações são baseadas no conhecimento atual e podem modificar-se com o tempo. Assim, esta revisão não deve ser utilizada para aplicação direta no cuidado do paciente sem levar em conta características da doença, do doador e fatores de risco do próprio paciente. Este trabalho não deve ainda ser utilizado como documento que limite o acesso do paciente ao transplante adequadamente indicado. Ressaltamos ainda, nesta revisão, diferenças entre transplantes em crianças e em adultos, com algumas recomendações específicas para os transplantes em pediatria.UNIFESPUniversidade Federal do ParanáUFRGSHospital Amaral CarvalhoHospital de Clínicas de Porto AlegreUNIFESPSciEL

Robust high-dimensional precision matrix estimation

The dependency structure of multivariate data can be analyzed using the covariance matrix $\Sigma$. In many fields the precision matrix $\Sigma^{-1}$ is even more informative. As the sample covariance estimator is singular in high-dimensions, it cannot be used to obtain a precision matrix estimator. A popular high-dimensional estimator is the graphical lasso, but it lacks robustness. We consider the high-dimensional independent contamination model. Here, even a small percentage of contaminated cells in the data matrix may lead to a high percentage of contaminated rows. Downweighting entire observations, which is done by traditional robust procedures, would then results in a loss of information. In this paper, we formally prove that replacing the sample covariance matrix in the graphical lasso with an elementwise robust covariance matrix leads to an elementwise robust, sparse precision matrix estimator computable in high-dimensions. Examples of such elementwise robust covariance estimators are given. The final precision matrix estimator is positive definite, has a high breakdown point under elementwise contamination and can be computed fast

Estimation of capture probabilities using generalized estimating equations and mixed effects approaches

Modeling individual heterogeneity in capture probabilities has been one of the most challenging tasks in capture-recapture studies. Heterogeneity in capture probabilities can be modeled as a function of individual covariates, but correlation structure among capture occasions should be taking into account. A proposed generalized estimating equations (GEE) and generalized linear mixed modeling (GLMM) approaches can be used to estimate capture probabilities and population size for capture-recapture closed population models. An example is used for an illustrative application and for comparison with currently used methodology. A simulation study is also conducted to show the performance of the estimation procedures. Our simulation results show that the proposed quasi-likelihood based on GEE approach provides lower SE than partial likelihood based on either generalized linear models (GLM) or GLMM approaches for estimating population size in a closed capture-recapture experiment. Estimator performance is good if a large proportion of individuals are captured. For cases where only a small proportion of individuals are captured, the estimates become unstable, but the GEE approach outperforms the other methods