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University of Technology of Compiègne, France

Magniez F.,University Paris DiderotParisFrance | Nayak A.,University of WaterlooWaterlooCanada | Santha M.,University Paris DiderotParisFrance | Sherman J.,University of CaliforniaBerkeley | And 2 more authors.
Random Structures and Algorithms | Year: 2015

We consider the randomized decision tree complexity of the recursive 3-majority function. We prove a lower bound of (1/2-δ)·2.57143h for the two-sided-error randomized decision tree complexity of evaluating height h formulae with error δ∈[0,1/2). This improves the lower bound of (1-2δ)(7/3)h given by Jayram, Kumar, and Sivakumar (STOC'03), and the one of (1-2δ)·2.55h given by Leonardos (ICALP'13). Second, we improve the upper bound by giving a new zero-error randomized decision tree algorithm that has complexity at most (1.007)·2.64944h. The previous best known algorithm achieved complexity (1.004)·2.65622h. The new lower bound follows from a better analysis of the base case of the recursion of Jayram et al. The new algorithm uses a novel "interleaving" of two recursive algorithms. © 2015 Wiley Periodicals, Inc. Source


Yousefi P.,University of CaliforniaBerkeley | Huen K.,University of CaliforniaBerkeley | Quach H.,University of CaliforniaBerkeley | Motwani G.,University of CaliforniaBerkeley | And 3 more authors.
Environmental and Molecular Mutagenesis | Year: 2015

Confounding by cellular heterogeneity has become a major concern for epigenome-wide association studies (EWAS) in peripheral blood samples from population and clinical studies. Adjusting for white blood cell percentage estimates produced by the minfi implementation of the Houseman algorithm (minfi) during statistical analysis is now an established method to account for this bias in adults. However, minfi has not been benchmarked against white blood cell counts in children that may differ substantially from the reference dataset used in its estimation. We compared estimates of white blood cell type percentages produced by two methods, minfi and differential cell count (DCC), in a birth cohort at two time points (birth and 12 years of age). We found that both minfi and DCC had similar trends as children aged, and neither count method differed by sex among newborns (P>0.10). However, minfi estimates did not correlate well with DCC in samples from newborns (ρ=-0.05 for granulocytes; ρ=-0.03 for lymphocytes). In older children, correlation improved substantially (ρ=0.77 for granulocytes; ρ=0.75 for lymphocytes), likely due to increasing similarity with minfi's adult reference data as children aged. Our findings suggest that the minfi method may provide suitable estimates of white blood cell composition for samples from adults and older children, but may not currently be appropriate for EWAS involving newborns or young children. © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc. Source


Catalano R.,University of CaliforniaBerkeley | Goodman J.,University of CaliforniaBerkeley | Margerison-Zilko C.,University of CaliforniaBerkeley | Falconi A.,University of CaliforniaBerkeley | And 3 more authors.
American Journal of Human Biology | Year: 2015

Objectives: The "dysregulated parturition" narrative posits that the human stress response includes a cascade of hormones that "dysregulates" and accelerates parturition but provides questionable utility as a guide to understand or prevent preterm birth. We offer and test a "strategic parturition" narrative that not only predicts the excess preterm births that dysregulated parturition predicts but also makes testable, sex-specific predictions of the effect of stressful environments on the timing of birth among term pregnancies. Methods: We use interrupted time-series modeling of cohorts conceived over 101 months to test for lengthening of early term male gestations in stressed population. We use an event widely reported to have stressed Americans and to have increased the incidence of low birth weight and fetal death across the country-the terrorist attacks of September 2001. We tested the hypothesis that the odds of male infants conceived in December 2000 (i.e., at term in September 2001) being born early as opposed to full term fell below the value expected from those conceived in the 50 prior and 50 following months. Results: We found that term male gestations exposed to the terrorist attacks exhibited 4% lower likelihood of early, as opposed to full or late, term birth. Conclusions: Strategic parturition explains observed data for which the dysregulated parturition narrative offers no prediction-the timing of birth among gestations stressed at term. Our narrative may help explain why findings from studies examining associations between population- and/or individual-level stressors and preterm birth are generally mixed. © 2015 Wiley Periodicals, Inc. Source

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