87 research outputs found
Censored data considerations and analytical approaches for salivary bioscience data
Left censoring in salivary bioscience data occurs when salivary analyte determinations fall below the lower limit of an assayâs measurement range. Conventional statistical approaches for addressing censored values (i.e., recoding as missing, substituting or extrapolating values) may introduce systematic bias. While specialized censored data statistical approaches (i.e., Maximum Likelihood Estimation, Regression on Ordered Statistics, Kaplan-Meier, and general Tobit regression) are available, these methods are rarely implemented in biobehavioral studies that examine salivary biomeasures, and their application to salivary data analysis may be hindered by their sensitivity to skewed data distributions, outliers, and sample size. This study compares descriptive statistics, correlation coefficients, and regression parameter estimates generated via conventional and specialized censored data approaches using salivary C-reactive protein data. We assess differences in statistical estimates across approach and across two levels of censoring (9% and 15%) and examine the sensitivity of our results to sample size. Overall, findings were similar across conventional and censored data approaches, but the implementation of specialized censored data approaches was more efficient (i.e., required little manipulations to the raw analyte data) and appropriate. Based on our review of the findings, we outline preliminary recommendations to enable investigators to more efficiently and effectively reduce statistical bias when working with left-censored salivary biomeasure data
Oral microbial communities in children, caregivers, and associations with salivary biomeasures and environmental tobacco smoke exposure
Human oral microbial communities are diverse, with implications for oral and systemic health. Oral microbial communities change over time; thus, it is important to understand how healthy versus dysbiotic oral microbiomes differ, especially within and between families. There is also a need to understand how the oral microbiome composition is changed within an individual including by factors such as environmental tobacco smoke (ETS) exposure, metabolic regulation, inflammation, and antioxidant potential. Using archived saliva samples collected from caregivers and children during a 90-month follow-up assessment in a longitudinal study of child development in the context of rural poverty, we used 16S rRNA gene sequencing to determine the salivary microbiome. A total of 724 saliva samples were available, 448 of which were from caregiver/child dyads, an additional 70 from children and 206 from adults. We compared childrenâs and caregiversâ oral microbiomes, performed âstomatotypeâ analyses, and examined microbial relations with concentrations of salivary markers associated with ETS exposure, metabolic regulation, inflammation, and antioxidant potential (i.e., salivary cotinine, adiponectin, C-reactive protein, and uric acid) assayed from the same biospecimens. Our results indicate that children and caregivers share much of their oral microbiome diversity, but there are distinct differences. Microbiomes from intrafamily individuals are more similar than microbiomes from nonfamily individuals, with child/caregiver dyad explaining 52% of overall microbial variation. Notably, children harbor fewer potential pathogens than caregivers, and participantsâ microbiomes clustered into two groups, with major differences being driven by Streptococcus spp. Differences in salivary microbiome composition associated with ETS exposure, and taxa associated with salivary analytes representing potential associations between antioxidant potential, metabolic regulation, and the oral microbiome
Measurement of in Collisions at TeV
We present the first observation of the baryon decay
followed by in 106 pb-1
of collisions at TeV in the CDF experiment. In
order to reduce systematic error, the measured rate for decay is
normalized to the kinematically similar meson decay followed
by . We report the ratio of production cross sections
() times the ratio of branching fractions (BR) for the momentum region
integrated above GeV/c and pseudorapidity range :
.Comment: Submitted to Phys.Rev.Let
Observation of Orbitally Excited B_s Mesons
We report the first observation of two narrow resonances consistent with
states of orbitally excited (L=1) B_s mesons using 1 fb^{-1} of ppbar
collisions at sqrt{s} = 1.96 TeV collected with the CDF II detector at the
Fermilab Tevatron. We use two-body decays into K^- and B^+ mesons reconstructed
as B^+ \to J/\psi K^+, J/\psi \to \mu^+ \mu^- or B^+ \to \bar{D}^0 \pi^+,
\bar{D}^0 \to K^+ \pi^-. We deduce the masses of the two states to be m(B_{s1})
= 5829.4 +- 0.7 MeV/c^2 and m(B_{s2}^*) = 5839.7 +- 0.7 MeV/c^2.Comment: Version accepted and published by Phys. Rev. Let
Fine-Scale in Situ Measurement of Riverbed Nitrate Production and Consumption in an Armored Permeable Riverbed
Alteration of the global nitrogen cycle by man has increased nitrogen loading in waterways considerably, often with harmful consequences for aquatic ecosystems. Dynamic redox conditions within riverbeds support a variety of nitrogen transformations, some of which can attenuate this burden. In reality, however, assessing the importance of processes besides perhaps denitrification is difficult, due to a sparseness of data, especially in situ, where sediment structure and hydrologic pathways are intact. Here we show in situ within a permeable riverbed, through injections of 15N-labeled substrates, that nitrate can be either consumed through denitrification or produced through nitrification, at a previously unresolved fine (centimeter) scale. Nitrification and denitrification occupy different niches in the riverbed, with denitrification occurring across a broad chemical gradient while nitrification is restricted to more oxic sediments. The narrow niche width for nitrification is in effect a break point, with the switch from activity âonâ to activity âoffâ regulated by interactions between subsurface chemistry and hydrology. Although maxima for denitrification and nitrification occur at opposing ends of a chemical gradient, high potentials for both nitrate production and consumption can overlap when groundwater upwelling is strong
Intimate mixing â bridging the gap? Catholic-Protestant relationships in Northern Ireland
Measurement of the ttbar Production Cross Section in ppbar collisions at sqrt s = 1.96 TeV in the All Hadronic Decay Mode
We report a measurement of the ttbar production cross section using the
CDF-II detector at the Fermilab Tevatron. The analysis is performed using 311
pb-1 of ppbar collisions at sqrt(s)=1.96 TeV. The data consist of events
selected with six or more hadronic jets with additional kinematic requirements.
At least one of these jets must be identified as a b-quark jet by the
reconstruction of a secondary vertex. The cross section is measured to be
sigma(tbart)=7.5+-2.1(stat.)+3.3-2.2(syst.)+0.5-0.4(lumi.) pb, which is
consistent with the standard model prediction.Comment: By CDF collaboratio
Search for chargino-neutralino production in ppbar collisions at sqrt(s) = 1.96 TeV
We present the results of a search for associated production of the chargino
and neutralino supersymmetric particles using up to 1.1 fb-1 of integrated
luminosity collected by the CDF II experiment at the Tevatron ppbar collider at
a center-of-mass energy of 1.96 TeV. The search is conducted by analyzing
events with a large transverse momentum imbalance and either three charged
leptons or two charged leptons of the same electric charge. The numbers of
observed events are found to be consistent with standard model expectations.
Upper limits on the production cross section are derived in different
theoretical models. In one of these models a lower limit on the mass of the
chargino is set at 129 GeV/c^2 at the 95% confidence level.Comment: To be submitted to Phys.Rev.Let
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Ancestral origin of ApoE Δ4 Alzheimer disease risk in Puerto Rican and African American populations
The ApoE Δ4 allele is the most significant genetic risk factor for late-onset Alzheimer disease. The risk conferred by Δ4, however, differs across populations, with populations of African ancestry showing lower Δ4 risk compared to those of European or Asian ancestry. The cause of this heterogeneity in risk effect is currently unknown; it may be due to environmental or cultural factors correlated with ancestry, or it may be due to genetic variation local to the ApoE region that differs among populations. Exploring these hypotheses may lead to novel, population-specific therapeutics and risk predictions. To test these hypotheses, we analyzed ApoE genotypes and genome-wide array data in individuals from African American and Puerto Rican populations. A total of 1,766 African American and 220 Puerto Rican individuals with late-onset Alzheimer disease, and 3,730 African American and 169 Puerto Rican cognitively healthy individuals (> 65 years) participated in the study. We first assessed average ancestry across the genome (âglobalâ ancestry) and then tested it for interaction with ApoE genotypes. Next, we assessed the ancestral background of ApoE alleles (âlocalâ ancestry) and tested if ancestry local to ApoE influenced Alzheimer disease risk while controlling for global ancestry. Measures of global ancestry showed no interaction with ApoE risk (Puerto Rican: p-value = 0.49; African American: p-value = 0.65). Conversely, ancestry local to the ApoE region showed an interaction with the ApoE Δ4 allele in both populations (Puerto Rican: p-value = 0.019; African American: p-value = 0.005). ApoE Δ4 alleles on an African background conferred a lower risk than those with a European ancestral background, regardless of population (Puerto Rican: OR = 1.26 on African background, OR = 4.49 on European; African American: OR = 2.34 on African background, OR = 3.05 on European background). Factors contributing to the lower risk effect in the ApoE gene Δ4 allele are likely due to ancestry-specific genetic factors near ApoE rather than non-genetic ethnic, cultural, and environmental factors
Prenatal exome sequencing analysis in fetal structural anomalies detected by ultrasonography (PAGE):a cohort study
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