7,089 research outputs found
Easy Come, EZ-GO: A Federal Role in Removing Jurisdictional Impediments to College Education
Outlines the need to raise college degree attainment by creating Educational Zone Governance Organizations in multistate metropolitan regions to coordinate and incentivize policies that expand access. Offers data by metro area, age, and race/ethnicity
Middle Darriwilian conodont zones in the uppermost San Juan limestone and the lower member of the Las Aguaditas formation, central Precordillera of San Juan, Argentina
The geological province of Precordillera is located in western Argentina. It extends 450 km meridionally and 110 km from east to west (Fig. 1) (Furque and Cuerda, 1979). The Lower Paleozoic stratigraphy is characterized by a thick succession of Cambro-Ordovician limestones, which were deposited in platform environments and interdigitate with clastic slope deposits toward the west (Keller et al., 1993; Astini, 1995).Fil: Feltes, Nicolás Alexis. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Museo de Paleontología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Albanesi, Guillermo Luis. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Museo de Paleontología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigaciones en Ciencias de la Tierra. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Centro de Investigaciones en Ciencias de la Tierra; ArgentinaFil: Bergström, S. M.. Ohio State University; Estados Unido
Meta-analysis of RNA-seq expression data across species, tissues and studies.
BackgroundDifferences in gene expression drive phenotypic differences between species, yet major organs and tissues generally have conserved gene expression programs. Several comparative transcriptomic studies have observed greater similarity in gene expression between homologous tissues from different vertebrate species than between diverse tissues of the same species. However, a recent study by Lin and colleagues reached the opposite conclusion. These studies differed in the species and tissues analyzed, and in technical details of library preparation, sequencing, read mapping, normalization, gene sets, and clustering methods.ResultsTo better understand gene expression evolution we reanalyzed data from four studies, including that of Lin, encompassing 6-13 tissues each from 11 vertebrate species using standardized mapping, normalization, and clustering methods. An analysis of independent data showed that the set of tissues chosen by Lin et al. were more similar to each other than those analyzed by previous studies. Comparing expression in five common tissues from the four studies, we observed that samples clustered exclusively by tissue rather than by species or study, supporting conservation of organ physiology in mammals. Furthermore, inter-study distances between homologous tissues were generally less than intra-study distances among different tissues, enabling informative meta-analyses. Notably, when comparing expression divergence of tissues over time to expression variation across 51 human GTEx tissues, we could accurately predict the clustering of expression for arbitrary pairs of tissues and species.ConclusionsThese results provide a framework for the design of future evolutionary studies of gene expression and demonstrate the utility of comparing RNA-seq data across studies
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Predictors of Therapists Use of Homework in Community Mental Health: Session and Therapist Characteristics
Assigning and reviewing homework as a strategy to help clients gain therapeutic skills is a common technique used across a variety of evidence-based practices (EBPs) and has been shown to improve therapy outcomes for children and youth. However, in studies characterizing routine psychotherapy delivered in community mental health settings, homework is rarely used in sessions. While some therapist and client level predictors of EBP strategy use have been identified in routine psychotherapy (e.g. client stressors, therapists’ attitudes towards EBPs) it is unknown what is associated with community mental health therapists using homework in the increasingly common context of system-driven implementation of multiple EBPs. To identify predictors of therapists’ use of homework, 680 videos of sessions with 274 clients were collected from 103 therapists (of which 55% were Hispanic) providing children’s mental health services through the Los Angeles County Department of Mental Health (LACDMH). The current study uses a multilevel logistic regression analysis model to identify which factors are associated with therapist use of homework in therapy sessions when there is system-driven implementation support for the use of multiple EBPs in community mental health settings. After controlling for the EBP delivered in session and the number of EBPs therapists were trained in, having a caregiver present in the therapy session, older child age, and being an unlicensed therapist were associated with a higher likelihood of therapists assigning and reviewing homework during a specific session. Therapist race/ethnicity, perceptions of the EBP being delivered, their report of emotional exhaustion, and direct hours with clients, as well as emergent unexpected stressful client life events within a session were not significantly associated with therapists’ delivery of homework. These findings underscore the need to provide explicit attention during therapist training on the use of homework with younger clients when caregivers are absent from sessions and the need to facilitate the use of homework among licensed therapists
Analyzing and Visualizing State Sequences in R with TraMineR
This article describes the many capabilities offered by the TraMineR toolbox for categorical sequence data. It focuses more specifically on the analysis and rendering of state sequences. Addressed features include the description of sets of sequences by means of transversal aggregated views, the computation of longitudinal characteristics of individual sequences and the measure of pairwise dissimilarities. Special emphasis is put on the multiple ways of visualizing sequences. The core element of the package is the state se- quence object in which we store the set of sequences together with attributes such as the alphabet, state labels and the color palette. The functions can then easily retrieve this information to ensure presentation homogeneity across all printed and graphical displays. The article also demonstrates how TraMineRâÂÂs outcomes give access to advanced analyses such as clustering and statistical modeling of sequence data.
Variation in physiological responses of forest trees to disturbance: implications for future forest carbon and management
Rapid environmental change in recent decades has challenged Ecologists to focus on understanding ecosystem response and physiological functioning in the face of increased disturbances. Understanding physiological responses of trees to disturbance and climatic variability can enable researchers to manage ecosystems to ensure continued ecological functioning in the future. In this dissertation, I use classic dendroecology, tree physiology theory, original stable isotope methodology, and a novel analytical model to explore the impacts of disturbance and climate variability on Quercus species in forested ecosystems in the Midwestern U.S. Anthropogenic land use changes along with increased occurrence of pathogen, pest, and climatic disturbance events are impacting forest ecosystems. A tree's susceptibility to decline following disturbance events must be assessed to understand changes to forest ecosystem function and distribution, especially at species boundaries, with predicted future increases in the frequency of disturbances such as drought in the Midwestern U.S. The oak ecosystems of eastern Kansas and the mixed oak-hickory forests of northwest Arkansas have experienced high levels of climatic variability in the past 5 decades, which have influenced differential physiological responses of co-occurring species. In Chapter 1, I investigate differential physiological response to pest and drought disturbances in co-occurring Quercus rubra. By examining growth, stable carbon, oxygen and nitrogen isotopes in tree-rings, and contemporary leaf nitrogen dynamics, I show that differential stable carbon and oxygen isotope relationships in tree-rings, along with leaf nitrogen relationships, suggest varied susceptibility to disturbance among well-interspersed, co-occurring trees. The differential responses of co-occurring species may provide insight into future forest composition under the prediction of increased disturbance events. In Chapter 2, I use two co-occurring species to explore the impacts of climate variability on physiological responses. I investigate climate relationships through growth, stable isotopes in tree-rings, and contemporary leaf data in an effort to understand the future of these species at their western range boundaries at the prairie-forest ecotone of North America. I suggest that a typically drought-vulnerable species exhibits stable carbon and oxygen isotopic values suggestive of greater water stress relative to a less drought-prone oak species and find evidence hinting at differences in factors influencing carbon source:sink dynamics related to response to vapor pressure deficit (VPD) and photosynthetic regulation. Comparing these data to the C source:sink dynamics of the more drought-tolerant, co-occurring oak leads me to explore nitrogen dynamics in an effort to understand the impacts of climate variability on these species' growth. The dynamics studied in this forest-prairie ecotone at the University of Kansas Field Station provide insight into the changing forest dynamics in coming decades under predicted increases in drought disturbance events. Nonlinear patterns in ecological systems can provide insight into capacity of a system to deal with variability. In Chapter 3, I use simplex and s-map forecasting models to assess nonlinearity in growth between healthy and dying trees to determine if nonlinear growth dynamics may relate to a tree's vulnerability to mortality following disturbance events for two forested regions in northwestern and west-central Arkansas, USA. By applying nonlinear forecasting models in a novel manner, I investigate the utility of discerning non-linear vs. linear dynamics in growth for understanding forest ecosystem dynamics and predictions of adaptability of trees to climatic variability. I also explore data concatenation, or stringing together of time series to increase statistical power, of tree-ring data sets to assess the presence of nonlinearity pre- and post-drought disturbance events, and the potential use of concatenation with nonlinear forecasting models as a tool for exploring the future of forest ecosystems with predicted increases in disturbance events. I suggest that nonlinear growth dynamics are linked to increased capacity to adapt to variability for trees, and discuss why this may be the case. Disturbance events are predicted to increase in frequency and duration under future climate change. Maintaining forest ecosystems, and their ability to cope with stress, is thus an increasing concern for forest managers. In Chapter 4, I explore forest management policy and its impacts on forest decline events in northwest Arkansas. I review the management policies of our nation's forests, and suggest adaptive management strategies and monitoring tools for decreasing the vulnerability of forests to future disturbance events. I suggest that management policies should address local goals for increasing biodiversity and adaptability of forests in the future and recommend ecosystem monitoring tools for forest managers. The results of this dissertation suggest that increasing frequency of forest disturbances will have significant ramifications for forest ecosystems through impacts on forest ecophysiological function, species distribution, and carbon and nutrient cycling. Detection of disturbance vulnerability may help in managers develop strategies for increasing forest adaptability to disturbances such as droughts and pest infestations
Optical and Theoretical Studies of Excitons in Few-Layer Lead Iodide.
Optical measurements and first-principles calculations of few-layer lead iodide (PbI2) crystals are presented in this work. Results indicate that the band structure and exciton energies change dramatically from direct-gap bulk to few-layer PbI2. Moreover, the n = 1 exciton appears to be Frenkel-like in nature, in that its energy exhibits a weak dependence on thickness down to atomic length scales. Calculations predict large increases of the gap and exciton binding energy with decreasing number of layers, as well as a transition of the fundamental gap from direct to indirect for 1 - 2 layers. Results are in reasonable agreement with a simple particle-in-a-box model relying on the Wannier-Mott theory of exciton formation. General arguments and existing data suggest that the Frenkel-like character of the lowest exciton is a common feature of wide-gap layered semiconductors whose effective masses and dielectric constants yield bulk Bohr radii on the order of the layer separation. In addition, experimental observations of exciton mediated multiphonon resonant Raman scattering in few-layer PbI2 are presented. Results demonstrate that the resonance and overtone scattering strength can be tuned with varying crystal thickness. This is shown to be an effective technique for the characterization of few-layer polar semiconductors such as PbI2.PHDApplied PhysicsUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/116665/1/atlouse_1.pd
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