714 research outputs found
Tracking Oregon's Progress: A Report of the Tracking Oregon's Progress (TOP) Indicators Project
In 1989, Oregon embarked on a novel experiment to track the progress of the state toward a set of economic, social and environmental goals embodied in the state strategic plan Oregon Shines. The task of tracking a set of indicators to measure progress was assigned to a new state entity: the Oregon Progress Board. For two decades, the Progress Board measured the state's progress using a set of social, economic and environmental indicators. After the 2009 report was completed however, the state decided not to continue funding the Progress Board and discontinued the tracking of state and county indicators.This 2014 report is a report to the people of Oregon. It identifies trends in the state that suggest both progress toward prosperity as well as issues that may be a source of future barriers and concerns. Like those who led previous indicator efforts, we hope that the report and website will be used by policymakers, government analysts, the press, business and civic leaders and the civically-engaged population to better understand the current social, economic, and environmental condition of the state
Chromatin: a tunable spring at work inside chromosomes
This paper focuses on mechanical aspects of chromatin biological functioning.
Within a basic geometric modeling of the chromatin assembly, we give for the
first time the complete set of elastic constants (twist and bend persistence
lengths, stretch modulus and twist-stretch coupling constant) of the so-called
30-nm chromatin fiber, in terms of DNA elastic properties and geometric
properties of the fiber assembly. The computation naturally embeds the fiber
within a current analytical model known as the ``extensible worm-like rope'',
allowing a straightforward prediction of the force-extension curves. We show
that these elastic constants are strongly sensitive to the linker length, up to
1 bp, or equivalently to its twist, and might locally reach very low values,
yielding a highly flexible and extensible domain in the fiber. In particular,
the twist-stretch coupling constant, reflecting the chirality of the chromatin
fiber, exhibits steep variations and sign changes when the linker length is
varied.
We argue that this tunable elasticity might be a key feature for chromatin
function, for instance in the initiation and regulation of transcription.Comment: 38 pages 15 figure
K-12 Student Success: Out-of-School time Initiative
This report is a summary of interim findings from the ongoing evaluation of the K-12 Student Success: Out-of-School Time Initiative
Influence of organic molecules on the aggregation of TiO2 nanoparticles in acidic conditions
Engineered nanoparticles released into the environment may interact with natural organic matter (NOM). Surface complexation affects the surface potential, which in turn may lead to aggregation of the particles. Aggregation of synthetic TiO2 (anatase) nanoparticles in aqueous suspension was investigated at pH 2.8 as a function of time in the presence of various organic molecules and Suwannee River fulvic acid (SRFA), using dynamic light scattering (DLS) and high-resolution transmission electron microscopy (TEM). Results showed that the average hydrodynamic diameter and ?-potential were dependent on both concentration and molecular structure of the organic molecule. Results were also compared with those of quantitative batch adsorption experiments. Further, a time study of the aggregation of TiO2 nanoparticles in the presence of 2,3-dihydroxybenzoic acid (2,3-DHBA) and SRFA, respectively, was performed in order to observe changes in ?-potential and particle size over a time period of 9 months. In the 2,3-DHBA-TiO2 system, ?-potentials decreased with time resulting in charge neutralization and/or inversion depending on ligand concentration. Aggregate sizes increased initially to the micrometer size range, followed by disaggregation after several months. No or very little interaction between SRFA and TiO2 occurred at the lowest concentrations tested. However, at the higher concentrations of SRFA, there was an increase in both aggregate size and the amount of SRFA adsorbed to the TiO2 surface. This was in correlation with the ?-potential that decreased with increased SRFA concentration, leading to destabilization of the system. These results stress the importance of performing studies over both short and long time periods to better understand and predict the long-term effects of nanoparticles in the environment
Combination of Isosorbide Dinitrate and Hydralazine in Blacks with Heart Failure
BACKGROUND We examined whether a fixed dose of both isosorbide dinitrate and hydralazine provides additional benefit in blacks with advanced heart failure, a subgroup previously noted to have a favorable response to this therapy. METHODS A total of 1050 black patients who had New York Heart Association class III or IV heart failure with dilated ventricles were randomly assigned to receive a fixed dose ofisosorbide dinitrate plus hydralazine or placebo in addition to standard therapy for heart failure. The primary end point was a composite score made up of weighted values for death from any cause, a first hospitalization for heart failure, and change in the quality of life. RESULTS The study was terminated early owing to a significantly higher mortality rate in the placebo group than in the group given isosorbide dinitrate plus hydralazine (10.2 percent vs. 6.2 percent, P=0.02). The mean primary composite score was significantly better in the group given isosorbide dinitrate plus hydralazine than in the placebo group (-0.1±1.9 vs. -0.5±2.0, P=0.01; range of possible values, -6 to + 2), as were its individual components (43 percent reduction in the rate of death from any cause [hazard ratio, 0.57; P=0.01] 33 percent relative reduction in the rate of first hospitalization for heart failure [16.4 percent vs. 22.4 percent, P=0.001], and an improvement in the quality of life [change in score, -5.6±20.6 vs. -2.7±21.2, with lower scores indicating better quality of life; P=0.02; range of possible values, 0 to 105]). CONCLUSIONS The addition ofa fixed dose of isosorbide dinitrate plus hydralazine to standard therapy for heart failure including neurohormonal blockers is efficacious and increases survival among black patients with advanced heart failure
A model for Escherichia coli chromosome packaging supports transcription factor-induced DNA domain formation
What physical mechanism leads to organization of a highly condensed and confined circular chromosome? Computational modeling shows that confinement-induced organization is able to overcome the chromosome's propensity to mix by the formation of topological domains. The experimentally observed high precision of separate subcellular positioning of loci (located on different chromosomal domains) in Escherichia coli naturally emerges as a result of entropic demixing of such chromosomal loops. We propose one possible mechanism for organizing these domains: regulatory control defined by the underlying E. coli gene regulatory network requires the colocalization of transcription factor genes and target genes. Investigating this assumption, we find the DNA chain to self-organize into several topologically distinguishable domains where the interplay between the entropic repulsion of chromosomal loops and their compression due to the confining geometry induces an effective nucleoid filament-type of structure. Thus, we propose that the physical structure of the chromosome is a direct result of regulatory interactions. To reproduce the observed precise ordering of the chromosome, we estimate that the domain sizes are distributed between 10 and 700 kb, in agreement with the size of topological domains identified in the context of DNA supercoiling
An All-Atom Model of the Chromatin Fiber Containing Linker Histones Reveals a Versatile Structure Tuned by the Nucleosomal Repeat Length
In the nucleus of eukaryotic cells, histone proteins organize the linear genome into a functional and hierarchical architecture. In this paper, we use the crystal structures of the nucleosome core particle, B-DNA and the globular domain of H5 linker histone to build the first all-atom model of compact chromatin fibers. In this 3D jigsaw puzzle, DNA bending is achieved by solving an inverse kinematics problem. Our model is based on recent electron microscopy measurements of reconstituted fiber dimensions. Strikingly, we find that the chromatin fiber containing linker histones is a polymorphic structure. We show that different fiber conformations are obtained by tuning the linker histone orientation at the nucleosomes entry/exit according to the nucleosomal repeat length. We propose that the observed in vivo quantization of nucleosomal repeat length could reflect nature's ability to use the DNA molecule's helical geometry in order to give chromatin versatile topological and mechanical properties
The Effect of Micrococcal Nuclease Digestion on Nucleosome Positioning Data
Eukaryotic genomes are packed into chromatin, whose basic repeating unit is the nucleosome. Nucleosome positioning is a widely researched area. A common experimental procedure to determine nucleosome positions involves the use of micrococcal nuclease (MNase). Here, we show that the cutting preference of MNase in combination with size selection generates a sequence-dependent bias in the resulting fragments. This strongly affects nucleosome positioning data and especially sequence-dependent models for nucleosome positioning. As a consequence we see a need to re-evaluate whether the DNA sequence is a major determinant of nucleosome positioning in vivo. More generally, our results show that data generated after MNase digestion of chromatin requires a matched control experiment in order to determine nucleosome positions
Measuring Client Satisfaction and Engagement: The Role of a Mentor Parent Program in Family Drug Treatment Court
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