3,438 research outputs found
Gasser-Leutwyler coefficients: A progress report
Last year, we reported our first results on the determination of
Gasser-Leutwyler coefficients using partially quenched lattice QCD with three
flavors of dynamical staggered quarks. We give an update on our progress in
determining two of these coefficients, including an exhaustive effort to
estimate all sources of systematic error. At this conference, we have heard
about algorithmic techniques to reduce staggered flavor symmetry breaking and a
method to incorporate staggered flavor breaking into the partially quenched
chiral Lagrangian. We comment on our plans to integrate these developments into
our ongoing program.Comment: 3 pages, 2 figures, Lattice2002(spectrum
MicroRNAs (miRNAs) in Neurodegenerative Diseases
Aging-related neurodegenerative diseases (NDs) are the culmination of many different genetic and environmental influences. Prior studies have shown that RNAs are pathologically altered during the inexorable course of some NDs. Recent evidence suggests that microRNAs (miRNAs) may be a contributing factor in neurodegeneration. miRNAs are brain-enriched, small (~22 nucleotides) non-coding RNAs that participate in mRNA translational regulation. Although discovered in the framework of worm development, miRNAs are now appreciated to play a dynamic role in many mammalian brain-related biochemical pathways, including neuroplasticity and stress responses. Research about miRNAs in the context of neurodegeneration is accumulating rapidly, and the goal of this review is to provide perspective for these new data that may be helpful to specialists in either field. An overview is provided about the normal functions for miRNAs, including some of the newer concepts related to the human brain. Recently published studies pertaining to the roles of miRNAs in NDs––including Alzheimer’s disease, Parkinson’s disease and triplet repeat disorders—are described. Finally, a discussion is included with theoretical syntheses and possible future directions in exploring the nexus between miRNA and ND research
Long gravitational-wave transients and associated detection strategies for a network of terrestrial interferometers
Searches for gravitational waves (GWs) traditionally focus on persistent sources (e.g., pulsars or the stochastic background) or on transients sources (e.g., compact binary inspirals or core-collapse supernovae), which last for time scales of milliseconds to seconds. We explore the possibility of long GW transients with unknown waveforms lasting from many seconds to weeks. We propose a novel analysis technique to bridge the gap between short O(s) “burst” analyses and persistent stochastic analyses. Our technique utilizes frequency-time maps of GW strain cross power between two spatially separated terrestrial GW detectors. The application of our cross power statistic to searches for GW transients is framed as a pattern recognition problem, and we discuss several pattern-recognition techniques. We demonstrate these techniques by recovering simulated GW signals in simulated detector noise. We also recover environmental noise artifacts, thereby demonstrating a novel technique for the identification of such artifacts in GW interferometers. We compare the efficiency of this framework to other techniques such as matched filtering
A Comparison of Methods to Communicate Treatment Preferences in Nursing Facilities: Traditional Practices versus the Physician Orders for Life-Sustaining Treatment (POLST) Program
Background
Traditional methods to communicate life-sustaining treatment preferences are largely ineffective. The Physician Orders for Life-Sustaining Treatment (POLST) Program offers an alternative approach, but comparative data are lacking.
Objectives
To evaluate the relationship between communication methods (POLST versus traditional practices) and documentation of life-sustaining treatment orders, symptom assessment and management, and use of life-sustaining treatments.
Design
Retrospective observational cohort study conducted between June 2006 and April 2007.
Setting
A stratified, random sample of 90 Medicaid-eligible nursing facilities in Oregon, Wisconsin, and West Virginia.
Subjects
1711 living and deceased nursing facility residents aged 65 and older with a minimum 60-day stay.
Measurements
Life-sustaining treatment orders; pain, shortness of breath, and related treatments over a 7-day period; and use of life-sustaining treatments over a 60-day period.
Results
POLST users were more likely to have orders about life-sustaining treatment preferences beyond CPR than non-POLST users (98.0% vs. 16.1%, P<.001). There were no differences between POLST users and non-users in symptom assessment or management. POLST users with orders for Comfort Measures Only were less likely to receive medical interventions (e.g., hospitalization) than residents with POLST Full Treatment orders (P=.004), residents with Traditional DNR orders (P<.001), or residents with Traditional Full Code orders (P<.001).
Conclusion
POLST users were more likely to have treatment preferences documented as medical orders than non-POLST users but there were no differences in symptom management or assessment. POLST orders restricting medical interventions were associated with the lower use of life-sustaining treatments. Findings suggest the POLST program offers significant advantages over traditional methods to communicate preferences about life-sustaining treatments
The Expression of MicroRNA miR-107 Decreases Early in Alzheimer\u27s Disease and May Accelerate Disease Progression through Regulation of β-Site Amyloid Precursor Protein-Cleaving Enzyme 1
MicroRNAs (miRNAs) are small regulatory RNAs that participate in posttranscriptional gene regulation in a sequence-specific manner. However, little is understood about the role(s) of miRNAs in Alzheimer\u27s disease (AD). We used miRNA expression microarrays on RNA extracted from human brain tissue from the University of Kentucky Alzheimer\u27s Disease Center Brain Bank with near-optimal clinicopathological correlation. Cases were separated into four groups: elderly nondemented with negligible AD-type pathology, nondemented with incipient AD pathology, mild cognitive impairment (MCI) with moderate AD pathology, and AD. Among the AD-related miRNA expression changes, miR-107 was exceptional because miR-107 levels decreased significantly even in patients with the earliest stages of pathology. In situ hybridization with cross-comparison to neuropathology demonstrated that particular cerebral cortical laminas involved by AD pathology exhibit diminished neuronal miR-107 expression. Computational analysis predicted that the 3′-untranslated region (UTR) of β-site amyloid precursor protein-cleaving enzyme 1 (BACE1) mRNA is targeted multiply by miR-107. From the same RNA material analyzed on miRNA microarrays, mRNA expression profiling was performed using Affymetrix Exon Array microarrays on nondemented, MCI, and AD patients. BACE1 mRNA levels tended to increase as miR-107 levels decreased in the progression of AD. Cell culture reporter assays performed with a subset of the predicted miR-107 binding sites indicate the presence of at least one physiological miR-107 miRNA recognition sequence in the 3′-UTR of BACE1 mRNA. Together, the coordinated application of miRNA profiling, Affymetrix microarrays, new bioinformatics predictions, in situ hybridization, and biochemical validation indicate that miR-107 may be involved in accelerated disease progression through regulation of BACE1
Novel Human \u3cem\u3eABCC9/SUR2\u3c/em\u3e Brain-Expressed Transcripts and an eQTL Relevant to Hippocampal Sclerosis of Aging
ABCC9 genetic polymorphisms are associated with increased risk for various human diseases including hippocampal sclerosis of aging. The main goals of this study were 1 \u3e to detect the ABCC9 variants and define the specific 3′ untranslated region (3′UTR) for each variant in human brain, and 2 \u3e to determine whether a polymorphism (rs704180) associated with risk for hippocampal sclerosis of aging pathology is also associated with variation in ABCC9 transcript expression and/or splicing. Rapid amplification of ABCC9 cDNA ends (3′RACE) provided evidence of novel 3′ UTR portions of ABCC9 in human brain. In silico and experimental studies were performed focusing on the single nucleotide polymorphism, rs704180. Analyses from multiple databases, focusing on rs704180 only, indicated that this risk allele is a local expression quantitative trait locus (eQTL). Analyses of RNA from human brains showed increased ABCC9 transcript levels in individuals with the risk genotype, corresponding with enrichment for a shorter 3′ UTR which may be more stable than variants with the longer 3′ UTR. MicroRNA transfection experiments yielded results compatible with the hypothesis that miR‐30c causes down‐regulation of SUR2 transcripts with the longer 3′ UTR. Thus we report evidence of complex ABCC9 genetic regulation in brain, which may be of direct relevance to human disease
The PHASES Differential Astrometry Data Archive. V. Candidate Substellar Companions to Binary Systems
The Palomar High-precision Astrometric Search for Exoplanet Systems monitored
51 subarcsecond binary systems to evaluate whether tertiary companions as small
as Jovian planets orbited either the primary or secondary stars, perturbing
their otherwise smooth Keplerian motions. Six binaries are presented that show
evidence of substellar companions orbiting either the primary or secondary
star. Of these six systems, the likelihoods of two of the detected
perturbations to represent real objects are considered to be "high confidence",
while the remaining four systems are less certain and will require continued
observations for confirmation.Comment: 16 Pages, Accepted to A
Parity-Violating Excitation of the \Delta(1232): Hadron Structure and New Physics
We consider prospects for studying the parity-violating (PV) electroweak
excitation of the \Delta(1232) resonance with polarized electron scattering.
Given present knowledge of Standard Model parameters, such PV experiments could
allow a determination of the N -> \Delta electroweak helicity amplitudes. We
discuss the experimental feasibility and theoretical interpretability of such a
determination as well as the prospective implications for hadron structure
theory. We also analyze the extent to which a PV N -> \Delta measurement could
constrain various extensions of the Standard Model.Comment: 43 pages, RevTex, 8 PS figures, uses epsf.sty, rotate.sty, version to
appear in Nucl. Phys. A, main points emphasized, some typos correcte
Relativistic Transport Approach for Nucleus-Nucleus Collisions from SIS to SPS Energies
We formulate a covariant transport approach for high energy nucleus-nucleus
collisions where the real part of the nucleon selfenergies is fitted to nuclear
matter properties which are evaluated on the basis of a NJL-type Lagrangian for
the quark degrees of freedom. The parameters of the quark-model Lagrangian are
fixed by the Gell-Mann, Oakes and Renner relation, the pion- nucleon
-term, the nucleon energy as well as the nuclear binding energy at
saturation density . We find the resulting scalar and vector
selfenergies for nucleons to be well in line with either Dirac-Brueckner
computations for or those from the phenomenological
optical potential when accounting for a swelling of the nucleon at finite
nuclear matter density. The meson-baryon interaction density is modelled to
describe a decrease of the meson mass with baryon density. The imaginary part
of the hadron selfenergies is determined by a string fragmentation model which
accounts for the in-medium mass of hadrons in line with the 'chiral' dynamics
employed. The applicability of the transport approach is demonstrated in
comparison with experimental data from SIS to SPS energies. The enhancement of
the K ratio in A + A collisions compared to p + A reactions at AGS
energies is reproduced within the 'chiral' dynamics. Furthermore, detailed
predictions for the stopping in Pb + Pb collisions at 153 GeV/A are presented.Comment: 1 compressed uuencoded postscript file with 23 figures included, 45
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