704 research outputs found
Modeling the Differences in Counted Outcomes using Bivariate Copula Models: with Application to Mismeasured Counts
This paper makes three contributions. First, it uses copula functions to obtain a flexible bivariate parametric model for nonnegative integer-valued data (counts). Second, it recovers the distribution of the difference in the two counts from a specifed bivariate count distribution. Third, the methods are applied to counts that are measured with error. Specifically we model the determinants of the difference between the self-reported number of doctor visits (measured with error) and true number of doctor visits (also available in the data used).
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One Size Fits All? Molecular Evidence for a Commonly Inherited Petal Identity Program in Ranunculales
Petaloid organs are a major component of the floral diversity observed across nearly all major clades of angiosperms. The variable morphology and development of these organs has led to the hypothesis that they are not homologous but, rather, have evolved multiple times. A particularly notable example of petal diversity, and potential homoplasy, is found within the order Ranunculales, exemplified by families such as Ranunculaceae, Berberidaceae, and Papaveraceae. To investigate the molecular basis of petal identity in Ranunculales, we used a combination of molecular phylogenetics and gene expression analysis to characterize APETALA3 (AP3) and PISTILLATA (PI) homologs from a total of 13 representative genera of the order. One of the most striking results of this study is that expression of orthologs of a single AP3 lineage is consistently petal-specific across both Ranunculaceae and Berberidaceae. We conclude from this finding that these supposedly homoplastic petals in fact share a developmental genetic program that appears to have been present in the common ancestor of the two families. We discuss the implications of this type of molecular data for long-held typological definitions of petals and, more broadly, the evolution of petaloid organs across the angiosperms.Organismic and Evolutionary Biolog
Characterization of the dorsal ulnar corner in distal radius fractures : implication for surgical decision making
Poster presented at the 2017 Health Sciences Research Day which was organized and sponsored by the University of Missouri School of Medicine Research Council and held on November 9, 2017.Conclusions: 3D segmentation software is effective in producing 3D distal radius fracture models that can be used for analysis. The study demonstrated a pattern in dorsal ulnar corner fragment shape, though the study population size should be increased to improve the power of the results. The data will improve understanding of the morphology and size of the dorsal ulnar corner fracture fragment, which is critical to understanding the optimal method of operative fixation. This information will also lead to development of more accurate intra-articularfracture models for biomechanical studies
Dynamic Cost-offsets of Prescription Drug Expenditures: Panel Data Analysis Using a Copula-based Hurdle Model
This paper presents a new multivariate copula-based modeling approach for analyzing cost-offsets between drug and nondrug expenditures. Estimates are based on panel data from the Medical Expenditure Panel Survey (MEPS) with quarterly measures of medical expenditures. The approach allows for nonlinear dynamic dependence between drug and nondrug expenditures as well as asymmetric contemporaneous dependence. The specification uses the standard hurdle model with two significant extensions. First, it is adapted to the bivariate case. Second, because the cost-offset hypothesis is inherently dynamic, the bivariate hurdle framework is extended to accommodate dynamic relationships between drug and nondrug spending. The econometric analysis is implemented for six different groups defined by specific health conditions. There is evidence of modest cost-offsets of expenditures on prescribed drugs.
σ,π‐Conjugated Bis(germylene) Adducts with NHC and CAACs
Heavier tetrylenes attract attention for their
potential in synthesis, catalysis and small molecule activation.
The coordination by N-heterocyclic carbenes (NHCs) and
cyclic (alkyl)(amino)carbenes (CAACs) results in substantial
structural and electronic differences although typically only
one of these yields stable derivatives for one and the same
tetrylene. We now report both NHC- and CAAC-coordination
to a bridged bis(germylene) motif. The NHC-coordinated
bis(germylene) exhibits pyramidal germanium centers with
lone pairs of electrons, while with CAAC an unprecedented
stable bis(germene) with two Ge=C bonds is isolated.
Spectroscopic and crystallographic evidence as well as DFT
calculations confirm the effects of σ,π-conjugation between
the two germanium centers in both cases. The coordination
of NHC is reversible as the reaction with BPh3 liberates the
transient bis(germylene) and thus provides an alternative
low-temperature route towards polymers with Ge=Ge bonds
Reactivity of Phenylacetylene toward Unsymmetrical Disilenes: Regiodivergent [2+2] Cycloaddition vs. CH Addition
We report the regiodivergent reaction of phenylacetylene with a selection of disilenes Tip2Si=SiTipR as well as bridged tetrasiladienes Tip2Si=SiTip−LU−SiTip=SiTip2 (Tip=2,4,6-iPr3C6H2, R=aryl groups; LU=arylene linkers). The regioselectivity of the [2+2] cycloaddition as determined by NMR spectroscopy and X-ray crystallography is shown to strongly depend on the nature of the substituent R. The small size of the substituents compared to the Tip groups in both cases suggests a change in mechanism between the substrates with only hydrogen in the ortho-positions of R and LU and those with either ortho-methyl groups or condensed aromatic rings. In contrast, the presence of catalytic quantities of base completely suppresses cycloaddtion in favor of the formal CH addition of phenylacetylene. Quenching reactions with either MeI or MeOH after the stoichiometric application of deprotonated phenylacetylene as well as NMR studies at low temperature prove the intermediacy of an alkynyl-substituted disilanyl lithium and thus suggest a carbolithiation pathway for the net CH addition
The distribution of invasive plant species of concern in the Kīlauea and Mauna Loa strip areas of Hawai‘i Volcanoes National Park, 2000-2010
Reports were scanned in black and white at a resolution of 600 dots per inch and were converted to text using Adobe Paper Capture Plug-in.Alien plant surveys conducted between 2000 and 2010 in Hawai‘i Volcanoes National
Park quantified the distribution of 134 alien plant species over 87,908 ha between sea level and 4,169 m elevation. Searches were conducted by foot, vehicle and helicopter and incorporated past survey and control data. Mapping identified 33 widespread species distributed broadly across the park and 101 locally distributed species with fewer, more discrete populations. Sixteen species were incipient invaders not previously known from the park, and an additional 15 new species were identified in a separate survey by Pratt et al. Relatively high concentrations of invasive species were found along roadsides and trails, particularly in the Kīlauea summit area, `Āinahou, the Mauna Loa rock quarry and Highway 11, where heavy visitation, high traffic, and importation of road building materials likely facilitated introduction and spread of species from outside areas. A geodatabase documenting the distribution of these species was generated, and survey data were compared to previous studies (Fosberg 1966; Tunison et. al. 1992) to evaluate changes in distribution and serve as a baseline for monitoring. Relative to the last parkwide mapping of localized species completed in 1992, eight species managed to control populations were found to have increased in abundance, while 30 apparently became less abundant. Thirteen managed species could not be relocated and may be extirpated. Key management recommendations based on survey results include expanding control to 13 additional species identified during this study, quickly eradicating all newly discovered species before they spread, intensifying monitoring in high risk areas, and expanding pre-emptive measures such as sanitation, public education, and prevention of deliberate plant introductions to the park
Social contact networks and mixing among students in K-12 schools in Pittsburgh, PA
Students attending schools play an important role in the transmission of influenza. In this study, we present a social network analysis of contacts among 1,828 students in eight different schools in urban and suburban areas in and near Pittsburgh, Pennsylvania, United States of America, including elementary, elementary-middle, middle, and high schools. We collected social contact information of students who wore wireless sensor devices that regularly recorded other devices if they are within a distance of 3 meters. We analyzed these networks to identify patterns of proximal student interactions in different classes and grades, to describe community structure within the schools, and to assess the impact of the physical environment of schools on proximal contacts. In the elementary and middle schools, we observed a high number of intra-grade and intra-classroom contacts and a relatively low number of inter-grade contacts. However, in high schools, contact networks were well connected and mixed across grades. High modularity of lower grades suggests that assumptions of homogeneous mixing in epidemic models may be inappropriate; whereas lower modularity in high schools suggests that homogenous mixing assumptions may be more acceptable in these settings. The results suggest that interventions targeting subsets of classrooms may work better in elementary schools than high schools. Our work presents quantitative measures of age-specific, school-based contacts that can be used as the basis for constructing models of the transmission of infections in schools
Towards More Precise Survey Photometry for PanSTARRS and LSST: Measuring Directly the Optical Transmission Spectrum of the Atmosphere
Motivated by the recognition that variation in the optical transmission of
the atmosphere is probably the main limitation to the precision of ground-based
CCD measurements of celestial fluxes, we review the physical processes that
attenuate the passage of light through the Earth's atmosphere. The next
generation of astronomical surveys, such as PanSTARRS and LSST, will greatly
benefit from dedicated apparatus to obtain atmospheric transmission data that
can be associated with each survey image. We review and compare various
approaches to this measurement problem, including photometry, spectroscopy, and
LIDAR. In conjunction with careful measurements of instrumental throughput,
atmospheric transmission measurements should allow next-generation imaging
surveys to produce photometry of unprecedented precision. Our primary concerns
are the real-time determination of aerosol scattering and absorption by water
along the line of sight, both of which can vary over the course of a night's
observations.Comment: 41 pages, 14 figures. Accepted PAS
Insecticide resistance mediated 1 by an exon skipping event
Many genes increase coding capacity by alternate exon usage. The gene encoding the insect nicotinic acetylcholine receptor (nAChR) a6 subunit, target of the bio-insecticide spinosad, is one example of this and expands protein diversity via alternative splicing of mutually exclusive exons. Here, we show that spinosad resistance in the tomato leaf miner, Tuta absoluta is associated with aberrant regulation of splicing of Taa6 resulting in a novel form of insecticide resistance mediated by exon skipping. Sequencing of the a6 subunit cDNA from spinosad selected and unselected strains of T. absoluta revealed all Taa6 transcripts of the selected strain were devoid of exon 3, with comparison of genomic DNA and mRNA revealing this is a result of exon skipping. Exon skipping cosegregated with spinosad resistance in survival bioassays, and functional characterization of this alteration using modified human nAChR a7, a model of insect a6, demonstrated that exon 3 is essential for receptor function and hence spinosad sensitivity. DNA and RNA sequencing analyses suggested that exon skipping did not result from genetic alterations in intronic or exonic cis-regulatory elements, but rather was associated with a single epigenetic modification downstream of exon 3a, and quantitative changes in the expression of trans-acting proteins that have known roles in the regulation of alternative splicing. Our results demonstrate that the intrinsic capacity of the a6 gene to generate transcript diversity via alternative splicing can be readily exploited during the evolution of resistance and identifies exon skipping as a molecular alteration conferring insecticide resistance
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