39 results match your criteria: "The University of Colorado at Boulder[Affiliation]"

Purpose: The goal of this study was to observe sensory gating-related networks underlying cortical auditory evoked potential (CAEP) peak components in individuals with and without minimal tinnitus, as measured using the Tinnitus Handicap Inventory (THI). This analysis was performed on previously published sensory gating responses in normal-hearing adults with and without minimal tinnitus.

Method: Independent component analysis was performed for each individual CAEP gating component (Pa, P50, N1, and P2).

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Optical manipulation and assembly of micro/nanoscale objects on solid substrates.

iScience

April 2022

Materials Science & Engineering Program, Texas Materials Institute, and Walker Department of Mechanical Engineering, The University of Texas at Austin, Austin, TX 78712, USA.

Many light-based technologies have been developed to manipulate micro/nanoscale objects such as colloidal particles and biological cells for basic research and practical applications. While most approaches such as optical tweezers are best suited for manipulation of objects in fluidic environments, optical manipulation on solid substrates has recently gained research interest for its advantages in constructing, reconfiguring, or powering solid-state devices consisting of colloidal particles as building blocks. Here, we review recent progress in optical technologies that enable versatile manipulation and assembly of micro/nanoscale objects on solid substrates.

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We present a methodology for defining and optimizing a general force field for classical molecular simulations, and we describe its use to derive the Open Force Field 1.0.0 small-molecule force field, codenamed Parsley.

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Dynamic equilibria in protein kinases.

Curr Opin Struct Biol

December 2021

Department of Biochemistry, The University of Colorado at Boulder, USA. Electronic address:

Structural changes involved in protein kinase activation and ligand binding have been determined from a wealth of X-ray crystallographic evidence. Recent solution studies using NMR, EPR, HX-MS, and fluorescence techniques have deepened this understanding by highlighting the underlying energetics and dynamics of multistate conformational ensembles. This new research is showing how activation mechanisms and ligand binding alter the internal motions of kinases and enable allosteric coupling between distal regulatory regions and the active site.

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Objective: To explore sexual orientation disparities in unwanted pregnancy by race/ethnicity.

Background: Previous research has documented that sexual-minority women (SMW) are more likely to report unplanned pregnancy than heterosexual women, and that Black and Latina women are more likely to report unplanned pregnancy than White women. No research has examined how pregnancy intention varies at the intersection of these two identities.

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We investigate the renormalized perturbative triples correction together with the externally corrected coupled-cluster singles and doubles (ecCCSD) method. We use the density matrix renormalization group (DMRG) and heat-bath CI (HCI) as external sources for the ecCCSD equations. The accuracy is assessed for the potential energy surfaces of HO, N, and F.

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Background: Pathogens are key components in natural and agricultural plant systems. There is evidence of evolutionary changes in disease susceptibility as a consequence of climate change, but we know little about the underlying genetic basis of this evolution. To address this, we took advantage of a historical seed collection of a Brassica rapa population, which we previously demonstrated evolved an increase in disease susceptibility to a necrotrophic fungal pathogen following a drought.

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We report on the findings of a blind challenge devoted to determining the frozen-core, full configuration interaction (FCI) ground-state energy of the benzene molecule in a standard correlation-consistent basis set of double-ζ quality. As a broad international endeavor, our suite of wave function-based correlation methods collectively represents a diverse view of the high-accuracy repertoire offered by modern electronic structure theory. In our assessment, the evaluated high-level methods are all found to qualitatively agree on a final correlation energy, with most methods yielding an estimate of the FCI value around -863 m.

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There is now abundant evidence of rapid evolution in natural populations, but the genetic mechanisms of these changes remain unclear. One possible route to rapid evolution is through changes in the expression of genes that influence traits under selection. We examined contemporary evolutionary gene expression changes in plant populations responding to environmental fluctuations.

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Although the linear method is one of the most robust algorithms for optimizing nonlinearly parametrized wavefunctions in variational Monte Carlo, it suffers from a memory bottleneck due to the fact that at each optimization step, a generalized eigenvalue problem is solved in which the Hamiltonian and overlap matrices are stored in memory. Here, we demonstrate that by applying the Jacobi-Davidson algorithm, one can solve the generalized eigenvalue problem iteratively without having to build and store the matrices in question. The resulting direct linear method greatly lowers the cost and improves the scaling of the algorithm with respect to the number of parameters.

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We interrogate state-level clustering of polygenic scores at different points in the life course and variation in the association of mean polygenic scores in a respondent's state of birth with corresponding phenotypes. The polygenic scores for height and smoking show the most state-level clustering (2 to 4 percent) with relatively little clustering observed for the other scores. However, even the small amounts of observed clustering are potentially meaningful.

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Regional Similarities and NO-related Increases in Biogenic Secondary Organic Aerosol in Summertime Southeastern U.S.

J Geophys Res Atmos

January 2018

Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, The University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.

During the 2013 Southern Oxidant and Aerosol Study, Fourier Transform Infrared Spectroscopy (FTIR) and Aerosol Mass Spectrometer (AMS) measurements of submicron mass were collected at Look Rock (LRK), Tennessee, and Centreville (CTR), Alabama. Carbon monoxide and submicron sulfate and organic mass concentrations were 15-60% higher at CTR than at LRK but their time series had moderate correlations (r~0.5).

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Fat metabolism has been linked to fertility and reproductive adaptation in animals and humans, and environmental sex determination potentially plays a role in the process. To investigate the impact of fatty acids (FA) on sex determination and reproductive development, we examined and observed an impact of FA synthesis and mobilization by lipolysis in somatic tissues on oocyte fate in Caenorhabditis elegans. The subsequent genetic analysis identified ACS-4, an acyl-CoA synthetase and its FA-CoA product, as key germline factors that mediate the role of FA in promoting oocyte fate through protein myristoylation.

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There is increasing evidence that evolution can occur rapidly in response to selection. Recent advances in sequencing suggest the possibility of documenting genetic changes as they occur in populations, thus uncovering the genetic basis of evolution, particularly if samples are available from both before and after selection. Here, we had a unique opportunity to directly assess genetic changes in natural populations following an evolutionary response to a fluctuation in climate.

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This article is an overview of household survey approaches for the comparative study of international migration dynamics. Focusing on differences in the drivers of international mobility at different times and places, I highlight the problems of obtaining data with adequate representation across time periods and geographies, and discuss a broad constellation of prospective and retrospective approaches, paying particular attention to the migration ethnosurvey. I place this methodology within a broader constellation of prospective and retrospective data collection techniques, briefly describing the advantages and disadvantages of each and summarizing the commonalities and differences of ethnosurvey approaches adopted around the world.

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Relative Equilibria in the Spherical, Finite Density Three-Body Problem.

J Nonlinear Sci

May 2016

Department of Aerospace Engineering Sciences, The University of Colorado at Boulder, Boulder, CO USA.

The relative equilibria for the spherical, finite density three-body problem are identified. Specifically, there are 28 distinct relative equilibria in this problem which include the classical five relative equilibria for the point-mass three-body problem. None of the identified relative equilibria exist or are stable over all values of angular momentum.

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Premise Of The Study: The antimicrobial properties and toxicity of Euphorbia plant latex should make it a hostile environment to microbes. However, when specimens from Euphorbia spp. were propagated in tissue culture, microbial growth was observed routinely, raising the question whether the latex of this diverse plant genus can be a niche for polymicrobial communities.

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Collective aspects of singlet fission in molecular crystals.

J Chem Phys

July 2015

Department of Chemistry and Biochemistry, The University of Colorado at Boulder, Boulder, Colorado 80309, USA.

We present a model to describe collective features of singlet fission in molecular crystals and analyze it using many-body theory. The model we develop allows excitonic states to delocalize over several chromophores which is consistent with the character of the excited states in many molecular crystals, such as the acenes, where singlet fission occurs. As singlet states become more delocalized and triplet states more localized, the rate of singlet fission increases.

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Compulsory licensing often did not produce lower prices for antiretrovirals compared to international procurement.

Health Aff (Millwood)

March 2015

Amir Attaran is a professor of common law and of population health at the Institute of Population Health, University of Ottawa, in Ontario.

Compulsory licensing has been widely suggested as a legal mechanism for bypassing patents to introduce lower-cost generic antiretrovirals for HIV/AIDS in developing countries. Previous studies found that compulsory licensing can reduce procurement prices for drugs, but it is unknown how the resulting prices compare to procurements through the Global Fund to Fight AIDS, Tuberculosis, and Malaria; UNICEF; and other international channels. For this study we systematically constructed a case-study database of compulsory licensing activity for antiretrovirals and compared compulsory license prices to those in the World Health Organization's (WHO's) Global Price Reporting Mechanism and the Global Fund's Price and Quality Reporting Tool.

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Introduction: While many have identified the important role of the developing brain in youth risk behavior, few have examined the relationship between salient cognitive factors (response inhibition) and different types of real-world adolescent health risk behaviors such as substance use and risky sex, within the same sample of youth.

Methods: We therefore sought to examine these relationships with 95 high-risk youth (ages 14-18; M age = 16.29 years).

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Background: Low retention rates are a problem for longitudinal studies involving adolescents, and this is particularly true for justice-involved youth.

Methods: This study evaluates (1) strategies used to retain high-risk adolescents participating in a longitudinal research project; (2) the extent to which retention efforts were different in a justice-involved versus a non-justice-involved (school-based) sample; and (3) differential characteristics of justice-involved versus school-based adolescents that might explain differences in retention difficulty.

Results: Compared with the school-based youth, justice-involved youth required significantly more phone calls to be successfully reached.

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This paper presents a detailed survival analysis for chronic kidney disease (CKD). The analysis is based on the EHR data comprising almost two decades of clinical observations collected at New York-Presbyterian, a large hospital in New York City with one of the oldest electronic health records in the United States. Our survival analysis approach centers around Bayesian multiresolution hazard modeling, with an objective to capture the changing hazard of CKD over time, adjusted for patient clinical covariates and kidney-related laboratory tests.

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Transcriptional regulation by hypoxia inducible factors.

Crit Rev Biochem Mol Biol

September 2014

Howard Hughes Medical Institute & Department of Molecular, Cellular and Developmental Biology, The University of Colorado at Boulder, Boulder, CO 80309-0347, U.S.A.

The cellular response to oxygen deprivation is governed largely by a family of transcription factors known as Hypoxia Inducible Factors (HIFs). This review focuses on the molecular mechanisms by which HIFs regulate the transcriptional apparatus to enable the cellular and organismal response to hypoxia. We discuss here how the various HIF polypeptides, their posttranslational modifications, binding partners and transcriptional cofactors affect RNA polymerase II activity to drive context-dependent transcriptional programs during hypoxia.

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A microscopic model of singlet fission.

J Phys Chem B

September 2012

Department of Chemistry and Biochemistry, The University of Colorado at Boulder, Boulder, Colorado 80309, USA.

Singlet fission, where an electronically excited singlet on one chromophore converts into a doubly excited state on two, has gone from a curiosity in organic photophysics to a potential pathway for increasing solar energy conversion efficiencies. Focusing on the role of solvent-induced energy level fluctuations that would be present in a dye-sensitized solar cell, we present a microscopic model for singlet fission. Starting from an electronic model Hamiltonian, we construct diabatic states in a manifold of single and double excitations with total singlet multiplicity and then develop a multilevel non-Markovian theory of dynamics for electronic populations in the presence of energy level fluctuations.

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