Showing papers by "University of Texas at Dallas published in 2010"
TL;DR: Principal component analysis (PCA) as discussed by the authors is a multivariate technique that analyzes a data table in which observations are described by several inter-correlated quantitative dependent variables, and its goal is to extract the important information from the table, to represent it as a set of new orthogonal variables called principal components, and display the pattern of similarity of the observations and of the variables as points in maps.
Abstract: Principal component analysis PCA is a multivariate technique that analyzes a data table in which observations are described by several inter-correlated quantitative dependent variables. Its goal is to extract the important information from the table, to represent it as a set of new orthogonal variables called principal components, and to display the pattern of similarity of the observations and of the variables as points in maps. The quality of the PCA model can be evaluated using cross-validation techniques such as the bootstrap and the jackknife. PCA can be generalized as correspondence analysis CA in order to handle qualitative variables and as multiple factor analysis MFA in order to handle heterogeneous sets of variables. Mathematically, PCA depends upon the eigen-decomposition of positive semi-definite matrices and upon the singular value decomposition SVD of rectangular matrices. Copyright © 2010 John Wiley & Sons, Inc.
6,398 citations
Rutgers University1, New York University2, University of Oxford3, Harvard University4, Bangor University5, University of Copenhagen6, National Institutes of Health7, Oregon Health & Science University8, Yale University9, Nathan Kline Institute for Psychiatric Research10, Medical College of Wisconsin11, University of Oulu12, Radboud University Nijmegen13, National Yang-Ming University14, Cleveland Clinic15, Duke University16, Max Planck Society17, Emory University18, University of Queensland19, University of Michigan20, Kennedy Krieger Institute21, Washington University in St. Louis22, Technische Universität München23, Leiden University24, University of Texas at Dallas25, Charité26, University of Pittsburgh27, Southeast University28, Otto-von-Guericke University Magdeburg29, Massachusetts Institute of Technology30, University of Western Ontario31, Medical University of Vienna32, Beijing Normal University33
TL;DR: The 1000 Functional Connectomes Project (Fcon_1000) as discussed by the authors is a large-scale collection of functional connectome data from 1,414 volunteers collected independently at 35 international centers.
Abstract: Although it is being successfully implemented for exploration of the genome, discovery science has eluded the functional neuroimaging community. The core challenge remains the development of common paradigms for interrogating the myriad functional systems in the brain without the constraints of a priori hypotheses. Resting-state functional MRI (R-fMRI) constitutes a candidate approach capable of addressing this challenge. Imaging the brain during rest reveals large-amplitude spontaneous low-frequency (<0.1 Hz) fluctuations in the fMRI signal that are temporally correlated across functionally related areas. Referred to as functional connectivity, these correlations yield detailed maps of complex neural systems, collectively constituting an individual's "functional connectome." Reproducibility across datasets and individuals suggests the functional connectome has a common architecture, yet each individual's functional connectome exhibits unique features, with stable, meaningful interindividual differences in connectivity patterns and strengths. Comprehensive mapping of the functional connectome, and its subsequent exploitation to discern genetic influences and brain-behavior relationships, will require multicenter collaborative datasets. Here we initiate this endeavor by gathering R-fMRI data from 1,414 volunteers collected independently at 35 international centers. We demonstrate a universal architecture of positive and negative functional connections, as well as consistent loci of inter-individual variability. Age and sex emerged as significant determinants. These results demonstrate that independent R-fMRI datasets can be aggregated and shared. High-throughput R-fMRI can provide quantitative phenotypes for molecular genetic studies and biomarkers of developmental and pathological processes in the brain. To initiate discovery science of brain function, the 1000 Functional Connectomes Project dataset is freely accessible at www.nitrc.org/projects/fcon_1000/.
2,787 citations
TL;DR: The authors provide a framework for analyzing the three main decisions that shape the corporate information environment in a capital markets setting: (1) managers' voluntary reporting and disclosure decisions, (2) reporting and disclosures mandated by regulators, and (3) reporting decisions by third-party intermediaries.
Abstract: The corporate information environment develops endogenously as a consequence of information asymmetries and agency problems between investors, entrepreneurs, and managers. We provide a framework for analyzing the three main decisions that shape the corporate information environment in a capital markets setting: (1) managers’ voluntary reporting and disclosure decisions, (2) reporting and disclosures mandated by regulators, and (3) reporting decisions by third-party intermediaries (analysts). We review current research on disclosure regulation, information intermediaries, and the determinants and economic consequences of corporate disclosure and financial reporting decisions. We conclude that in the last ten years, research has generated a number of useful insights. Despite this progress, we call for researchers to consider interdependencies between the various decisions that shape the corporate information environment and highlight changes in the economic financial environment that raise new and interesting issues for researchers to address.
1,648 citations
TL;DR: The chemical changes of oxygen-containing functional groups on the annealing of graphene oxide are elucidated and the simulations reveal the formation of highly stable carbonyl and ether groups that hinder its complete reduction to graphene.
Abstract: The excellent electrical, optical and mechanical properties of graphene have driven the search to find methods for its large-scale production, but established procedures (such as mechanical exfoliation or chemical vapour deposition) are not ideal for the manufacture of processable graphene sheets. An alternative method is the reduction of graphene oxide, a material that shares the same atomically thin structural framework as graphene, but bears oxygen-containing functional groups. Here we use molecular dynamics simulations to study the atomistic structure of progressively reduced graphene oxide. The chemical changes of oxygen-containing functional groups on the annealing of graphene oxide are elucidated and the simulations reveal the formation of highly stable carbonyl and ether groups that hinder its complete reduction to graphene. The calculations are supported by infrared and X-ray photoelectron spectroscopy measurements. Finally, more effective reduction treatments to improve the reduction of graphene oxide are proposed.
1,624 citations
TL;DR: The authors review current research on the three main decisions that shape the corporate information environment in capital market settings: (1) managers' voluntary disclosure decisions, (2) disclosures mandated by regulators, and (3) reporting decisions by analysts.
1,387 citations
Broad Institute1, University of Amsterdam2, University of California, Riverside3, University of Arizona4, Université Paris-Saclay5, University of Córdoba (Spain)6, Oregon State University7, Aix-Marseille University8, Pennsylvania State University9, Texas A&M University10, Purdue University11, University of California, Irvine12, Rothamsted Research13, Pacific Northwest National Laboratory14, University of Minnesota15, United States Department of Agriculture16, Centre national de la recherche scientifique17, University of Texas Southwestern Medical Center18, University of California, Los Angeles19, Commonwealth Scientific and Industrial Research Organisation20, Seoul National University21, University of Texas at Dallas22, University of Cambridge23, University of Wisconsin-Madison24, Cornell University25
TL;DR: Comparison of genomes of three phenotypically diverse Fusarium species revealed lineage-specific genomic regions in F. oxysporum that include four entire chromosomes and account for more than one-quarter of the genome, putting the evolution of fungal pathogenicity into a new perspective.
Abstract: Fusarium species are among the most important phytopathogenic and toxigenic fungi. To understand the molecular underpinnings of pathogenicity in the genus Fusarium, we compared the genomes of three phenotypically diverse species: Fusarium graminearum, Fusarium verticillioides and Fusarium oxysporum f. sp. lycopersici. Our analysis revealed lineage-specific (LS) genomic regions in F. oxysporum that include four entire chromosomes and account for more than one-quarter of the genome. LS regions are rich in transposons and genes with distinct evolutionary profiles but related to pathogenicity, indicative of horizontal acquisition. Experimentally, we demonstrate the transfer of two LS chromosomes between strains of F. oxysporum, converting a non-pathogenic strain into a pathogen. Transfer of LS chromosomes between otherwise genetically isolated strains explains the polyphyletic origin of host specificity and the emergence of new pathogenic lineages in F. oxysporum. These findings put the evolution of fungal pathogenicity into a new perspective.
1,386 citations
TL;DR: In this paper, the authors provided an up-to-date assessment of global mercury emissions from anthropogenic and natural sources, including re-emission processes and primary emissions from natural reservoirs.
Abstract: . This paper provides an up-to-date assessment of global mercury emissions from anthropogenic and natural sources. On an annual basis, natural sources account for 5207 Mg of mercury released to the global atmosphere, including the contribution from re-emission processes, which are emissions of previously deposited mercury originating from anthropogenic and natural sources, and primary emissions from natural reservoirs. Anthropogenic sources, which include a large number of industrial point sources, are estimated to account for 2320 Mg of mercury emitted annually. The major contributions are from fossil-fuel fired power plants (810 Mg yr−1), artisanal small scale gold mining (400 Mg yr−1), non-ferrous metals manufacturing (310 Mg yr−1), cement production (236 Mg yr−1), waste disposal (187 Mg yr−1) and caustic soda production (163 Mg yr−1). Therefore, our current estimate of global mercury emissions suggests that the overall contribution from natural sources (primary emissions + re-emissions) and anthropogenic sources is nearly 7527 Mg per year, the uncertainty associated with these estimates are related to the typology of emission sources and source regions.
1,240 citations
TL;DR: Partial least squares (PLS) regression as mentioned in this paper is a recent technique that combines features from and generalizes principal component analysis (PCA) and multiple linear regression, which can be used to predict a set of dependent variables from a subset of independent variables or predictors.
Abstract: Partial least squares (PLS) regression (a.k.a. projection on latent structures) is a recent technique that combines features from and generalizes principal component analysis (PCA) and multiple linear regression. Its goal is to predict a set of dependent variables from a set of independent variables or predictors. This prediction is achieved by extracting from the predictors a set of orthogonal factors called latent variables which have the best predictive power. These latent variables can be used to create displays akin to PCA displays. The quality of the prediction obtained from a PLS regression model is evaluated with cross-validation techniques such as the bootstrap and jackknife. There are two main variants of PLS regression: The most common one separates the roles of dependent and independent variables; the second one—used mostly to analyze brain imaging data—gives the same roles to dependent and independent variables. Copyright © 2010 John Wiley & Sons, Inc.
For further resources related to this article, please visit the WIREs website.
1,062 citations
TL;DR: The SCN network synchronizes its component cellular oscillators, reinforces their oscillations, responds to light input by altering their phase distribution, increases their robustness to genetic perturbations, and enhances their precision.
Abstract: The suprachiasmatic nucleus (SCN) is the primary circadian pacemaker in mammals. Individual SCN neurons in dispersed culture can generate independent circadian oscillations of clock gene expression and neuronal firing. However, SCN rhythmicity depends on sufficient membrane depolarization and levels of intracellular calcium and cAMP. In the intact SCN, cellular oscillations are synchronized and reinforced by rhythmic synaptic input from other cells, resulting in a reproducible topographic pattern of distinct phases and amplitudes specified by SCN circuit organization. The SCN network synchronizes its component cellular oscillators, reinforces their oscillations, responds to light input by altering their phase distribution, increases their robustness to genetic perturbations, and enhances their precision. Thus, even though individual SCN neurons can be cell-autonomous circadian oscillators, neuronal network properties are integral to normal function of the SCN.
1,045 citations
TL;DR: The effect of growth parameters such as temperature, and methane flow rate and partial pressure on the growth rate, domain size, and surface coverage of graphene as determined by Raman spectroscopy, and transmission and scanning electron microscopy is reported.
Abstract: The fundamental properties of graphene are making it an attractive material for a wide variety of applications. Various techniques have been developed to produce graphene and recently we discovered the synthesis of large area graphene by chemical vapor deposition (CVD) of methane on Cu foils. We also showed that graphene growth on Cu is a surface-mediated process and the films were polycrystalline with domains having an area of tens of square micrometers. In this paper, we report on the effect of growth parameters such as temperature, and methane flow rate and partial pressure on the growth rate, domain size, and surface coverage of graphene as determined by Raman spectroscopy, and transmission and scanning electron microscopy. On the basis of the results, we developed a two-step CVD process to synthesize graphene films with domains having an area of hundreds of square micrometers. Scanning electron microscopy and Raman spectroscopy clearly show an increase in domain size by changing the growth parameters...
988 citations
TL;DR: The use of cochlear implants in young children was associated with better spoken language learning than would be predicted from their preimplantation scores.
Abstract: Context Cochlear implantation is a surgical alternative to traditional amplification (hearing aids) that can facilitate spoken language development in young children with severe to profound sensorineural hearing loss (SNHL). Objective To prospectively assess spoken language acquisition following cochlear implantation in young children. Design, setting, and participants Prospective, longitudinal, and multidimensional assessment of spoken language development over a 3-year period in children who underwent cochlear implantation before 5 years of age (n = 188) from 6 US centers and hearing children of similar ages (n = 97) from 2 preschools recruited between November 2002 and December 2004. Follow-up completed between November 2005 and May 2008. Main outcome measures Performance on measures of spoken language comprehension and expression (Reynell Developmental Language Scales). Results Children undergoing cochlear implantation showed greater improvement in spoken language performance (10.4; 95% confidence interval [CI], 9.6-11.2 points per year in comprehension; 8.4; 95% CI, 7.8-9.0 in expression) than would be predicted by their preimplantation baseline scores (5.4; 95% CI, 4.1-6.7, comprehension; 5.8; 95% CI, 4.6-7.0, expression), although mean scores were not restored to age-appropriate levels after 3 years. Younger age at cochlear implantation was associated with significantly steeper rate increases in comprehension (1.1; 95% CI, 0.5-1.7 points per year younger) and expression (1.0; 95% CI, 0.6-1.5 points per year younger). Similarly, each 1-year shorter history of hearing deficit was associated with steeper rate increases in comprehension (0.8; 95% CI, 0.2-1.2 points per year shorter) and expression (0.6; 95% CI, 0.2-1.0 points per year shorter). In multivariable analyses, greater residual hearing prior to cochlear implantation, higher ratings of parent-child interactions, and higher socioeconomic status were associated with greater rates of improvement in comprehension and expression. Conclusion The use of cochlear implants in young children was associated with better spoken language learning than would be predicted from their preimplantation scores.
TL;DR: In this article, the ZIF-8/Matrimid ® MMMs were fabricated with loadings up to 80% (w/w), which is much higher than the typical loadings achieved with select zeolite materials.
TL;DR: The observation of a giant-infrared-absorption band in reduced graphene oxide is reported, arising from the coupling of electronic states to the asymmetric stretch mode of a yet-unreported structure, consisting of oxygen atoms aggregated at the edges of defects.
Abstract: Infrared absorption of atomic and molecular vibrations in solids can be affected by electronic contributions through non-adiabatic interactions, such as the Fano effect. Typically, the infrared-absorption lineshapes are modified, or infrared-forbidden modes are detectable as a modulation of the electronic absorption. In contrast to such known phenomena, we report here the observation of a giant-infrared-absorption band in reduced graphene oxide, arising from the coupling of electronic states to the asymmetric stretch mode of a yet-unreported structure, consisting of oxygen atoms aggregated at the edges of defects. Free electrons are induced by the displacement of the oxygen atoms, leading to a strong infrared absorption that is in phase with the phonon mode. This new phenomenon is only possible when all other oxygen-containing chemical species, including hydroxyl, carboxyl, epoxide and ketonic functional groups, are removed from the region adjacent to the edges, that is, clean graphene patches are present.
Baylor College of Medicine1, Washington University in St. Louis2, University of California, San Francisco3, University of British Columbia4, University of California, Santa Cruz5, University of California, Davis6, Salk Institute for Biological Studies7, Broad Institute8, Harvard University9, Ludwig Institute for Cancer Research10, University of California, San Diego11, University of Texas at Dallas12, Max Planck Society13
TL;DR: This work combined MeDIP-seq with methylation-sensitive restriction enzyme (MRE-seq) sequencing for comprehensive methylome coverage at lower cost and detected regions with allele-specific epigenetic states, identifying most known imprinted regions and new loci with Monoallelic epigenetic marks and monoallelic expression.
Abstract: Analysis of DNA methylation patterns relies increasingly on sequencing-based profiling methods. The four most frequently used sequencing-based technologies are the bisulfite-based methods MethylC-seq and reduced representation bisulfite sequencing (RRBS), and the enrichment-based techniques methylated DNA immunoprecipitation sequencing (MeDIP-seq) and methylated DNA binding domain sequencing (MBD-seq). We applied all four methods to biological replicates of human embryonic stem cells to assess their genome-wide CpG coverage, resolution, cost, concordance and the influence of CpG density and genomic context. The methylation levels assessed by the two bisulfite methods were concordant (their difference did not exceed a given threshold) for 82% for CpGs and 99% of the non-CpG cytosines. Using binary methylation calls, the two enrichment methods were 99% concordant and regions assessed by all four methods were 97% concordant. We combined MeDIP-seq with methylation-sensitive restriction enzyme (MRE-seq) sequencing for comprehensive methylome coverage at lower cost. This, along with RNA-seq and ChIP-seq of the ES cells enabled us to detect regions with allele-specific epigenetic states, identifying most known imprinted regions and new loci with monoallelic epigenetic marks and monoallelic expression.
TL;DR: In this article, the authors used the ATLAS detector to detect dijet asymmetry in the collisions of lead ions at the Large Hadron Collider and found that the transverse energies of dijets in opposite hemispheres become systematically more unbalanced with increasing event centrality, leading to a large number of events which contain highly asymmetric di jets.
Abstract: By using the ATLAS detector, observations have been made of a centrality-dependent dijet asymmetry in the collisions of lead ions at the Large Hadron Collider. In a sample of lead-lead events with a per-nucleon center of mass energy of 2.76 TeV, selected with a minimum bias trigger, jets are reconstructed in fine-grained, longitudinally segmented electromagnetic and hadronic calorimeters. The transverse energies of dijets in opposite hemispheres are observed to become systematically more unbalanced with increasing event centrality leading to a large number of events which contain highly asymmetric dijets. This is the first observation of an enhancement of events with such large dijet asymmetries, not observed in proton-proton collisions, which may point to an interpretation in terms of strong jet energy loss in a hot, dense medium.
University of Iowa1, National Institute of Advanced Industrial Science and Technology2, University of Texas at Dallas3, University of Rhode Island4, École normale supérieure de Lyon5, Oregon State University6, San Diego State University7, Florida International University8, Japan Agency for Marine-Earth Science and Technology9
TL;DR: A recent dive with the JAMSTEC Shinkai 6500 manned submersible in the Mariana fore arc southeast of Guam has discovered that MORB-like tholeiitic basalts crop out over large areas.
Abstract: Recent diving with the JAMSTEC Shinkai 6500 manned submersible in the Mariana fore arc southeast of Guam has discovered that MORB-like tholeiitic basalts crop out over large areas These ''fore-arc basalts'' (FAB) underlie boninites and overlie diabasic and gabbroic rocks Potential origins include eruption at a spreading center before subduction began or eruption during near-trench spreading after subduction began FAB trace element patterns are similar to those of MORB and most Izu-Bonin-Mariana (IBM) back-arc lavas However, Ti/V and Yb/V ratios are lower in FAB reflecting a stronger prior depletion of their mantle source compared to the source of basalts from mid-ocean ridges and back-arc basins Some FAB also have higher concentrations of fluid-soluble elements than do spreading center lavas Thus, the most likely origin of FAB is that they were the first lavas to erupt when the Pacific Plate began sinking beneath the Philippine Plate at about 51 Ma The magmas were generated by mantle decompression during near-trench spreading with little or no mass transfer from the subducting plate Boninites were generated later when the residual, highly depleted mantle melted at shallow levels after fluxing by a water-rich fluid derived from the sinking Pacific Plate This magmatic stratigraphy of FAB overlain by transitional lavas and boninites is similar to that found in many ophiolites, suggesting that ophiolitic assemblages might commonly originate from near-trench volcanism caused by subduction initiation Indeed, the widely dispersed Jurassic and Cretaceous Tethyan ophiolites could represent two such significant subduction initiation events
TL;DR: The found that chronic cocaine use selectively increased thin dendritic spines on NAc neurons and that DNA methylation was both necessary and sufficient to mediate these effects, establish the importance of Dnmt3a in the NAc in regulating cellular and behavioral plasticity to emotional stimuli.
Abstract: Despite abundant expression of DNA methyltransferases (Dnmt’s) in brain, the regulation and behavioral role of DNA methylation remain poorly understood. We find that Dnmt3a expression is regulated in mouse nucleus accumbens (NAc) by chronic cocaine and chronic social defeat stress. Moreover, NAc specific manipulations that block DNA methylation potentiate cocaine reward and exert antidepressant-like effects, whereas NAc specific Dnmt3a overexpression attenuates cocaine reward and is pro-depressant. On a cellular level, we show that chronic cocaine selectively increases thin dendritic spines on NAc neurons and that DNA methylation is both necessary and sufficient to mediate these effects. These data establish the importance of Dnmt3a in the NAc in regulating cellular and behavioral plasticity to emotional stimuli.
TL;DR: The potential for microRNAs to be targeted therapeutically in the treatment of cardiovascular disease is addressed, with a focus on the basic biology and mechanism of action of miRNAs specifically pertaining to cardiovascular disorders.
Abstract: Cardiovascular disease is the predominant cause of human morbidity and mortality in developed countries. Thus, extraordinary effort has been devoted to determining the molecular and pathophysiological characteristics of the diseased heart and vasculature with the goal of developing novel diagnostic and therapeutic strategies to combat cardiovascular disease. The collective work of multiple research groups has uncovered a complex transcriptional and posttranscriptional regulatory circuit, the integrity of which is essential for the maintenance of cardiac homeostasis. Mutations in or aberrant expression of various transcriptional and posttranscriptional regulators have now been correlated with human cardiac disease, and pharmacological modulation of the activity of these target genes is a major focus of ongoing research. Recently, a novel class of small noncoding RNAs, called microRNAs (miRNAs), was identified as important transcriptional and posttranscriptional inhibitors of gene expression thought to “fine tune” the translational output of target messenger RNAs (mRNAs).1,2 miRNAs are implicated in the pathogenesis of various cardiovascular diseases and have become an intriguing target for therapeutic intervention. This review focuses on the basic biology and mechanism of action of miRNAs specifically pertaining to cardiovascular disorders and addresses the potential for miRNAs to be targeted therapeutically in the treatment of cardiovascular disease.
miRNAs originate from longer precursor RNAs called primary miRNAs that are regulated by conventional transcription factors and transcribed by RNA polymerase II. Primary miRNAs are hundreds to thousands of nucleotides long and are processed in the nucleus into an ≈70- to 100-nucleotide hairpin-shaped precursor miRNA by the RNase III enzyme Drosha and the double-stranded RNA binding protein DGCR8. The precursor miRNA is then transported into the cytoplasm by the nuclear export factor exportin 5 and further processed into an ≈19- to 25-nucleotide double-stranded RNA by the RNaseIII enzyme Dicer. This duplex miRNA is then incorporated into the RNA-induced silencing complex. One …
TL;DR: Significant individual differences in shrinkage rates were observed in the lateral prefrontal cortex, the cerebellum, and all the white matter regions throughout the study, whereas additional regions showed significant individual variation in change during the second follow-up.
TL;DR: In this article, the authors performed searches for lepton-flavor-violating decays of a tau lepton to a lighter mass lepton and a photon with the entire data set of (963 +/- 7) x 10(6) tau decays collected by the BABAR detector near the Y(4S), Y(3S) and Y(2S) resonances.
Abstract: Searches for lepton-flavor-violating decays of a tau lepton to a lighter mass lepton and a photon have been performed with the entire data set of (963 +/- 7) x 10(6) tau decays collected by the BABAR detector near the Y(4S), Y(3S) and Y(2S) resonances. The searches yield no evidence of signals and we set upper limits on the branching fractions of B(tau(+/-) -> e(+/-)gamma) mu(+/-)gamma) < 4.4 X 10(-8) at 90% confidence level.
University of Pennsylvania1, Autonomous University of Barcelona2, Mayo Clinic3, University of Manchester4, Erasmus University Rotterdam5, VU University Amsterdam6, Indiana University – Purdue University Indianapolis7, University of Siena8, National Institutes of Health9, Neuroscience Research Australia10, University of Cambridge11, University of Michigan12, Oregon Health & Science University13, Northwestern University14, King's College London15, University of Texas at Dallas16, University of Texas Southwestern Medical Center17, University of Barcelona18, University of Zurich19, Ludwig Maximilian University of Munich20, Duke University21, University of California, San Francisco22, Veterans Health Administration23, Boston University24, Emory University25, University College London26, University of British Columbia27, University of Pittsburgh28, University of Virginia29, University of Antwerp30, Flanders Institute for Biotechnology31, Columbia University32, Johns Hopkins University33, University of Sydney34, University of New South Wales35, University of Washington36, University of Sheffield37, Washington University in St. Louis38, Alfred Hospital39, University of California, Davis40, Harvard University41, Icahn School of Medicine at Mount Sinai42, Rush University Medical Center43, University of Arizona44, University of California, Los Angeles45, University of Southern California46, Uppsala University47, University of Eastern Finland48, Pierre-and-Marie-Curie University49, University of California, San Diego50, University of California, Irvine51, University of Toronto52, University of Alabama at Birmingham53, University of Würzburg54, Karolinska Institutet55
TL;DR: It is found that FTLD-TDP associates with multiple SNPs mapping to a single linkage disequilibrium block on 7p21 that contains TMEM 106B, which implicate variants in TMEM106B as a strong risk factor for FTLD, suggesting an underlying pathogenic mechanism.
Abstract: Frontotemporal lobar degeneration (FTLD) is the second most common cause of presenile dementia. The predominant neuropathology is FTLD with TAR DNA-binding protein (TDP-43) inclusions (FTLD-TDP). FTLD-TDP is frequently familial, resulting from mutations in GRN (which encodes progranulin). We assembled an international collaboration to identify susceptibility loci for FTLD-TDP through a genome-wide association study of 515 individuals with FTLD-TDP. We found that FTLD-TDP associates with multiple SNPs mapping to a single linkage disequilibrium block on 7p21 that contains TMEM106B. Three SNPs retained genome-wide significance following Bonferroni correction (top SNP rs1990622, P = 1.08 x 10(-11); odds ratio, minor allele (C) 0.61, 95% CI 0.53-0.71). The association replicated in 89 FTLD-TDP cases (rs1990622; P = 2 x 10(-4)). TMEM106B variants may confer risk of FTLD-TDP by increasing TMEM106B expression. TMEM106B variants also contribute to genetic risk for FTLD-TDP in individuals with mutations in GRN. Our data implicate variants in TMEM106B as a strong risk factor for FTLD-TDP, suggesting an underlying pathogenic mechanism.
TL;DR: In this article, the impact of family ownership and control on firm value is associated with the level of shareholder protection embodied in legal and regulatory institutions of a country, and the contours of a cross-country, institution-based view of corporate governance are sketched.
Abstract: There is a major debate regarding the role of concentrated family ownership and control in large firms, with three positions suggesting that such concentration is (1) good, (2) bad, or (3) irrelevant for firm value. Why are there such differences? We theorize that the impact of family ownership and control on firm value is associated with the level of shareholder protection embodied in legal and regulatory institutions of a country. Data from 634 publicly listed large family firms in seven Asian countries (Hong Kong, Indonesia, Malaysia, Singapore, South Korea, Taiwan, and Thailand) are used to test our hypotheses. Overall, this article sketches the contours of a cross-country, institution-based view of corporate governance, and leads to a more informed understanding of the crucial role of institutions behind family ownership and control in large firms.
TL;DR: A poor initial hematopoietic response to darbepoetin alfa was associated with an increased subsequent risk of death or cardiovascular events as doses were escalated to meet target hemoglobin levels.
Abstract: Patients who had a poor initial response to darbepoetin alfa had a lower average hemoglobin level at 12 weeks and during follow-up than did patients with a better hemoglobin response (a change in hemoglobin level ranging from 2 to 15% or more) (P<0.001 for both comparisons), despite receiving higher doses of darbepoetin alfa (median dose, 232 μg vs. 167 μg; P<0.001). Patients with a poor response, as compared with those with a better response, had higher rates of the composite cardiovascular end point (adjusted hazard ratio, 1.31; 95% confidence interval [CI], 1.09 to 1.59) or death (adjusted hazard ratio, 1.41; 95% CI, 1.12 to 1.78). Conclusions A poor initial hematopoietic response to darbepoetin alfa was associated with an increased subsequent risk of death or cardiovascular events as doses were escalated to meet target hemoglobin levels. Although the mechanism of this differential effect is not known, these findings raise concern about current target-based strategies for treating anemia in patients with chronic kidney disease. (Funded by Amgen; ClinicalTrials.gov number, NCT00093015.)
TL;DR: This work studies the estimation of risk preferences with experimental data and focuses on the trade-offs when choosing between two different elicitation methods that have different degrees of difficulty for subjects, finding that subjects’ numerical skills can help assess this tradeoff.
Abstract: We study the estimation of risk preferences with experimental data and focus on the trade-offs when choosing between two different elicitation methods that have different degrees of difficulty for subjects. We analyze how and when a simpler, but coarser, elicitation method may be preferred to the more complex, but finer, one. Results indicate that the more complex measure has overall superior predictive accuracy, but its downside is that subjects exhibit noisier behavior. Our main result is that subjects’ numerical skills can help better assess this tradeoff: the simpler task may be preferred for subjects who exhibit low numeracy, as it generates less noisy behavior but similar predictive accuracy. For subjects with higher numerical skills, the greater predictive accuracy of the more complex task more than outweighs the larger noise. We also explore preference heterogeneity and provide methodological suggestions for future work.
TL;DR: On the FRVT 2006 and the ICE 2006 data sets, recognition performance was comparable for high-resolution frontal face, 3D face, and the iris images and the best performing algorithms were more accurate than humans on unfamiliar faces.
Abstract: This paper describes the large-scale experimental results from the Face Recognition Vendor Test (FRVT) 2006 and the Iris Challenge Evaluation (ICE) 2006. The FRVT 2006 looked at recognition from high-resolution still frontal face images and 3D face images, and measured performance for still frontal face images taken under controlled and uncontrolled illumination. The ICE 2006 evaluation reported verification performance for both left and right irises. The images in the ICE 2006 intentionally represent a broader range of quality than the ICE 2006 sensor would normally acquire. This includes images that did not pass the quality control software embedded in the sensor. The FRVT 2006 results from controlled still and 3D images document at least an order-of-magnitude improvement in recognition performance over the FRVT 2002. The FRVT 2006 and the ICE 2006 compared recognition performance from high-resolution still frontal face images, 3D face images, and the single-iris images. On the FRVT 2006 and the ICE 2006 data sets, recognition performance was comparable for high-resolution frontal face, 3D face, and the iris images. In an experiment comparing human and algorithms on matching face identity across changes in illumination on frontal face images, the best performing algorithms were more accurate than humans on unfamiliar faces.
TL;DR: Thermocells are demonstrated, in practical configurations, that harvest low-grade thermal energy using relatively inexpensive carbon multiwalled nanotube (MWNT) electrodes that provide high electrochemically accessible surface areas and fast redox-mediated electron transfer, which significantly enhances thermocell current generation capacity and overall efficiency.
Abstract: Low efficiencies and costly electrode materials have limited harvesting of thermal energy as electrical energy using thermo- electrochemical cells (or "thermocells"). We demonstrate thermocells, in practical configurations (from coin cells to cells that can be wrapped around exhaust pipes), that harvest low-grade thermal energy using relatively inexpensive carbon multiwalled nanotube (MWNT) electrodes. These electrodes provide high electrochemically accessible surface areas and fast redox-mediated electron transfer, which significantly enhances thermocell current generation capacity and overall efficiency. Thermocell efficiency is further improved by directly synthesizing MWNTs as vertical forests that reduce electrical and thermal resistance at electrode/substrate junctions. The efficiency of thermocells with MWNT electrodes is shown to be as high as 1.4% of Carnot efficiency, which is 3-fold higher than for previously demonstrated thermocells. With the cost of MWNTs decreasing, MWNT-based thermocells may become commercially viable for harvesting low-grade thermal energy.
TL;DR: Patients with remission of MDD after treatment with citalopram continue to experience selected residual depressive symptoms, which increase the risk of relapse.
Abstract: Background. Many patients with major depressive disorder (MDD) who experience full symptomatic remission after antidepressant treatment still have residual depressive symptoms. We describe the types and frequency of residual depressive symptoms and their relationship to subsequent depressive relapse after treatment with citalopram in the Sequenced Treatment Alternatives to Relieve Depression (STAR * D) trial. Method. Participants in primary (n=18) and psychiatric (n=23) practice settings were openly treated with citalopram using measurement-based care for up to 14 weeks and follow-up for up to 1 year. We assessed 943 (32.8% of 2876) participants who met criteria for remission to determine the proportions with individual residual symptoms and any of the nine DSM-IV criterion symptom domains to define a major depressive episode. At each visit, the 16-item Quick Inventory of Depressive Symptomatology, Self-Report (QIDS-SR 16 ) and the self-report Frequency, Intensity, and Burden of Side Effects Rating (FIBSER) scale were used to assessed depressive symptoms and side-effects respectively. Results. More than 90% of remitters had at least one residual depressive symptom (median=3). The most common were weight increase (71.3%) and mid-nocturnal insomnia (54.9%). The most common residual symptom domains were sleep disturbance (71.7%) and appetite/weight disturbance (35.9%). Those who remitted before 6 weeks had fewer residual symptoms at study exit than did later remitters. Residual sleep disturbance did not predict relapse during follow-up. Having a greater number of residual symptom domains was associated with a higher probability of relapse. Conclusions. Patients with remission of MDD after treatment with citalopram continue to experience selected residual depressive symptoms, which increase the risk of relapse.
TL;DR: A broad-brush overview of the new synthesis between neuroscientific and psychological approaches to cognitive aging is offered, including the Scaffolding Theory of Aging and Cognition and some new key discoveries are examined.
Abstract: In this article, marking the 65th anniversary of the Journal of Gerontology, we offer a broad-brush overview of the new synthesis between neuroscientific and psychological approaches to cognitive aging. We provide a selective review of brain imaging studies and their relevance to mechanisms of cognitive aging first identified primarily from behavioral measurements. We also examine some new key discoveries, including evidence favoring plasticity and compensation that have emerged specifically from using cognitive neuroscience methods to study healthy aging. We then summarize several recent neurocognitive theories of aging, including our own model-the Scaffolding Theory of Aging and Cognition. We close by discussing some newly emerging trends and future research trajectories for investigating the aging mind and brain.
TL;DR: A conceptually different approach to contrast enhancement is based on chemical exchange saturation transfer (CEST), which relies on dynamic chemical exchange processes inherent in biological tissues to transfer saturated 1H spins into the bulk water proton pool, which leads to a decrease of net magnetization and is detected as a negative contrast (darkening of the image) in MRI.
Abstract: Magnetic Resonance Imaging (MRI) has been immensely valuable in diagnostic clinical imaging over the last few decades owing to its exceptional spatial and anatomical resolution. The signal in MRI is generated by relaxation of the transverse component of the net magnetization of protons present in the body, predominantly from bulk water. Thus, any agent or process that affects the net magnetization of the water protons in body tissues will also influence image contrast. Gd3+-based contrast agents shorten both the longitudinal and transverse relaxation times (T1 and T2) of water protons to approximately the same extent, in essence by relaxing all nearby proton spins. This effect is detected as increased signal intensity in T1 weighted MRI images when the appropriate pulse sequence is applied. Over the past 25 years Gd3+-complexes have been spectacularly successful as extracellular or blood pool T1 agents but their relative insensitivity to changes in environment coupled with the fact that they are never completely silent limits their applicability in the design of responsive MRI agents. A conceptually different approach to contrast enhancement is based on chemical exchange saturation transfer (CEST). This technique relies on dynamic chemical exchange processes inherent in biological tissues to transfer saturated 1H spins into the bulk water proton pool, which leads to a decrease of net magnetization and is detected as a negative contrast (darkening of the image) in MRI. Originally exchangeable -NH and -OH protons of various biomolecules were used to generate CEST contrast (DIACEST). However, these agents suffer from a few drawbacks, particularly in association with the small, usually less than 6 ppm, chemical shift difference between the two exchanging pools. The great benefit of using paramagnetic hyperfine shifting lanthanide complexes as CEST agents (PARACEST) is that the chemical shift difference between the two exchanging pools can potentially be much larger, up to several hundred ppm, facilitating easy saturation of one of the exchangeable spin pools without partial saturation of the bulk water pool. Another advantage of PARACEST is that the exchangeable sites are not limited to -NH or -OH protons but sites with faster exchange rates such as a Ln3+-bound H2O molecule, in particular, can also be considered. Since the water exchange rate on lanthanide complexes is extremely sensitive to the chemical environment, this has created unprecedented opportunities in the design of responsive PARACEST agents. In addition, multi-frequency MRI imaging is inherent to PARACEST: multiple agents present in the body can be imaged in one experiment by selectively turning on and off each agent by applying the appropriate saturation frequency.
TL;DR: It is found that a combination of high stretchability and high electrical conductivity can be obtained for composites prepared from three-dimensional CNT structures, such as CNT forests (vertically aligned arrays of CNTs).
Abstract: Electrically conductive materials capable of substantial elastic stretch and bending are needed for such applications as smart clothing, flexible displays, stretchable circuits, strain gauges, implantable devices, high-stroke microelectromechanical systems, and dielectric elastomer actuators. A variety of approaches involving carbon nanotubes (CNTs) and elastic polymers have been suggested for the fabrication of conductive elastic composites. In particular, diverse active and passive electronic components have been embedded in rubber sheet by several research groups to obtain stretchable electronic devices. Sekitani et al. developed rubber-like conductive composites by mixing millimeter-long single-walled carbon nanotubes (SWNTs), an ionic liquid, and a fluorinated copolymer. The stretchability of the resulting composite was enhanced by creating perforated films with a net-shaped structure using a mechanical punching system. Cao et al. fabricated flexible electrodes by incorporating SWNTnetworks in plastics consisting of polyimide, polyurethane, and polyamic acid films. Although quite successful, these studies indicated that high loading of CNTs (or other conductive additive) was necessary to obtain a highly conducting composite. On the other hand, incorporation of high concentrations of CNTs into an elastic polymer increases the stiffness of the resulting composite and decreases its stretchability. In other words, the significant difference in the Young’s modulus of extremely rigid CNTs and the elastic polymer filler makes the creation of a highly stretchable conductive composites a challenging task. It is known that CNTs can be fabricated into macroscopic assemblies, such as mats (bucky paper), yarns, and fibers that possess useful electrical properties, and that these assemblies can be used for the fabrication of conductive polymer composites. While these assemblies are often more elastic than the individual CNTs, the achievable elastic strain range is still quite limited, normally less than 10%. We found that a combination of high stretchability and high electrical conductivity can be obtained for composites prepared from three-dimensional CNT structures, such as CNT forests (vertically aligned arrays of CNTs). Unlike previous methods involving casting CNT/ polymer dispersions as a film, our composites were prepared by the direct infiltration of multiwalled carbon nanotube (MWNT) forests with a polyurethane (PU) solution. Using this procedure, we obtained rubber-like forest/PU composites that combined high stretchability with high electrical conductivity. These composites provide highly reversible stress–strain behavior and little degradation of mechanical and electrical properties even when stretched over a wide strain range. The developed preparation procedure appears scalable for material fabrication on an industrial scale, though transition from present batchbased forest growth processes to continuous forest growth processes would be needed for applications that are price sensitive and depend on sheet weight, rather than the area of elastomeric sheet. The aligned arrays of MWNTs (MWNT forests) used in this study were grown on iron-catalyst-coated silicon wafers using a conventional chemical vapor deposition (CVD) method. Nanotubes in the forests typically had a diameter of about 10 nm; their length could be controlled across a wide range by changing the growth time and other fabrication conditions. The forest-covered area on the substrate used for the preparation of the composites typically had dimensions of about 50 100mm; the height of nanotubes in the forest was about 50mm as determined by the conventional optical microscopy. Since the nanotubes in the forests formed a three-dimensionally interconnected network, the forests were electrically conductive in all directions. The MWNT forests were infiltrated with a PU solution in N,N-dimethylformamide (DMF) using a simple drop-casting procedure, as shown in Figure 1a. The PU used was poly[4,40methylene-bis(phenyl isocyanate)-alt-1,4-butanediol/poly(butylene adipate)]. After evaporation of the solvent, we obtained about 250mm thick forest/PU composite sheets that could be peeled off the underlying Si wafer. Figure 1b shows a photograph of the MWNT/PU composite sheet taken at low magnification. One side of the prepared film facing the substrate (forest side) was black and conductive, and the other side (PU side) was white and insulating. The material was soft, flexible, and highly stretchable in the sheet plane. Figure 1c shows a SEM image of a cross-section of the composite sheet with the top ( 50mm in thickness) being the forest side and the bottom ( 200mm in thickness) being the PU side. A highmagnification image of the forest side is shown in the