747 research outputs found
Investigating Dementia via a multicompartmental poroelastic model of parenchymal tissue
In this paper, a workflow within the VPH-DARE@IT Clinical Research Platform is presented. This
is used to model the biomechanical behaviour of perfused brain tissue. This workflow features a 3D
multicompartmental poroelastic framework, patient-specific brain anatomy representations and
continuous waveforms of internal carotid and vertebral arteries, which are used as a means of
personalizing the boundary conditions that feed the arterial compartment of the in-house
poroelastic solver. Results are shown comparing CSF/ISF clearance and accumulation in two males
of similar age, both are non-smokers, however one is more active and is diagnosed with MCI and
experiences less sleep
Pre-surgical depression and anxiety and recovery following coronary artery bypass graft surgery
We aimed to explore the combined contribution of pre-surgical depression and anxiety symptoms for recovery following coronary artery bypass graft (CABG) using data from 251 participants. Participants were assessed prior to surgery for depression and anxiety symptoms and followed up at 12 months to assess pain and physical symptoms, while hospital emergency admissions and death/major adverse cardiac events (MACE) were monitored on average 2.68 years after CABG. After controlling for covariates, baseline anxiety symptoms, but not depression, were associated with greater pain (β = 0.231, p = 0.014) and greater physical symptoms (β = 0.194, p = 0.034) 12 months after surgery. On the other hand, after controlling for covariates, baseline depression symptoms, but not anxiety, were associated with greater odds of having an emergency admission (OR 1.088, CI 1.010–1.171, p = 0.027) and greater hazard of death/MACE (HR 1.137, CI 1.042–1.240, p = 0.004). These findings point to different pathways linking mood symptoms with recovery after CABG surgery
Astrocytic Ion Dynamics: Implications for Potassium Buffering and Liquid Flow
We review modeling of astrocyte ion dynamics with a specific focus on the
implications of so-called spatial potassium buffering, where excess potassium
in the extracellular space (ECS) is transported away to prevent pathological
neural spiking. The recently introduced Kirchoff-Nernst-Planck (KNP) scheme for
modeling ion dynamics in astrocytes (and brain tissue in general) is outlined
and used to study such spatial buffering. We next describe how the ion dynamics
of astrocytes may regulate microscopic liquid flow by osmotic effects and how
such microscopic flow can be linked to whole-brain macroscopic flow. We thus
include the key elements in a putative multiscale theory with astrocytes
linking neural activity on a microscopic scale to macroscopic fluid flow.Comment: 27 pages, 7 figure
The Hubble Constant
I review the current state of determinations of the Hubble constant, which
gives the length scale of the Universe by relating the expansion velocity of
objects to their distance. There are two broad categories of measurements. The
first uses individual astrophysical objects which have some property that
allows their intrinsic luminosity or size to be determined, or allows the
determination of their distance by geometric means. The second category
comprises the use of all-sky cosmic microwave background, or correlations
between large samples of galaxies, to determine information about the geometry
of the Universe and hence the Hubble constant, typically in a combination with
other cosmological parameters. Many, but not all, object-based measurements
give values of around 72-74km/s/Mpc , with typical errors of 2-3km/s/Mpc.
This is in mild discrepancy with CMB-based measurements, in particular those
from the Planck satellite, which give values of 67-68km/s/Mpc and typical
errors of 1-2km/s/Mpc. The size of the remaining systematics indicate that
accuracy rather than precision is the remaining problem in a good determination
of the Hubble constant. Whether a discrepancy exists, and whether new physics
is needed to resolve it, depends on details of the systematics of the
object-based methods, and also on the assumptions about other cosmological
parameters and which datasets are combined in the case of the all-sky methods.Comment: Extensively revised and updated since the 2007 version: accepted by
Living Reviews in Relativity as a major (2014) update of LRR 10, 4, 200
The scientific basis of climate-smart agriculture: A systematic review protocol
Background: ‘Climate-smart agriculture’ (CSA)—agriculture and food systems that
sustainably increase food production, improve resilience (or adaptive capacity) of farming
systems, and mitigate climate change when possible—has quickly been integrated into the
global development agenda. However, the empirical evidence base for CSA has not been
assembled, complicating the transition from CSA concept to concrete actions, and
contributing to ideological disagreement among development practitioners. Thus, there is an
urgent need to evaluate current knowledge on the effectiveness of CSA to achieve its intended
benefits and inform discourse on food, agriculture, and climate change. This systematic
review intends to establish the scientific evidence base of CSA practices to inform the next
steps in development of agricultural programming and policy. We will evaluate the impact of
73 promising farm-level management practices across five categories (agronomy,
agroforestry, livestock, postharvest management, and energy systems) to assess their
contributions to the three CSA pillars: (1) agronomic and economic productivity, (2)
resilience and adaptive capacity, and (3) climate change mitigation in the developing world.
The resulting data will be compiled into a searchable Web-based database and analytical
engine that can be used to assess the relative effectiveness and strength of evidence for CSA,
as well as identify best-fit practices for specific farming and development contexts. This
represents the largest meta-analysis of agricultural practices to date.
Methods/Design: This protocol sets out the approach for investigating the question: How do
farm-level CSA management practices and technologies affect food production and/or
farmers’ incomes, resilience/adaptive capacity, and climate change mitigation in farming
systems of developing countries? The objective of this ongoing systematic review is to
provide a first appraisal of the evidence for CSA practices in order to inform subsequent
programming. The review is based on data found in English-language peer-reviewed journals
with searches using terms relevant to CSA practices and CSA outcomes. Searches were
conducted via Web of Science (WoS) and Scopus. Articles located were screened first by
abstract and then full text according to predefined eligibility criteria for inclusion in the
review. Data capturing the context of the study (e.g., geographic location, environmental
context), management practices, and impacts (e.g., indicators of CSA outcomes) will be
compiled from those studies that meet the predetermined criteria. Statistical relationships
between practices and impacts will be evaluated via meta-analytical approaches including
response ratios and effect sizes. Mechanisms to identify bias and maintain consistency
continue to be applied throughout the review process. These analyses will be complemented
with an analysis of determinants of/barriers to adoption of promising CSA practices covered
in the meta-analysis. Results of the review will be incorporated into a publicly available Web-based
database. Data will be publicly available under Creative Commons License in 2016
Measurement of the top quark mass using the matrix element technique in dilepton final states
We present a measurement of the top quark mass in pp¯ collisions at a center-of-mass energy of 1.96 TeV at the Fermilab Tevatron collider. The data were collected by the D0 experiment corresponding to an integrated luminosity of 9.7 fb−1. The matrix element technique is applied to tt¯ events in the final state containing leptons (electrons or muons) with high transverse momenta and at least two jets. The calibration of the jet energy scale determined in the lepton+jets final state of tt¯ decays is applied to jet energies. This correction provides a substantial reduction in systematic uncertainties. We obtain a top quark mass of mt=173.93±1.84 GeV
A review of elliptical and disc galaxy structure, and modern scaling laws
A century ago, in 1911 and 1913, Plummer and then Reynolds introduced their
models to describe the radial distribution of stars in `nebulae'. This article
reviews the progress since then, providing both an historical perspective and a
contemporary review of the stellar structure of bulges, discs and elliptical
galaxies. The quantification of galaxy nuclei, such as central mass deficits
and excess nuclear light, plus the structure of dark matter halos and cD galaxy
envelopes, are discussed. Issues pertaining to spiral galaxies including dust,
bulge-to-disc ratios, bulgeless galaxies, bars and the identification of
pseudobulges are also reviewed. An array of modern scaling relations involving
sizes, luminosities, surface brightnesses and stellar concentrations are
presented, many of which are shown to be curved. These 'redshift zero'
relations not only quantify the behavior and nature of galaxies in the Universe
today, but are the modern benchmark for evolutionary studies of galaxies,
whether based on observations, N-body-simulations or semi-analytical modelling.
For example, it is shown that some of the recently discovered compact
elliptical galaxies at 1.5 < z < 2.5 may be the bulges of modern disc galaxies.Comment: Condensed version (due to Contract) of an invited review article to
appear in "Planets, Stars and Stellar
Systems"(www.springer.com/astronomy/book/978-90-481-8818-5). 500+ references
incl. many somewhat forgotten, pioneer papers. Original submission to
Springer: 07-June-201
A single, one-off measure of depression and anxiety predicts future symptoms, higher healthcare costs, and lower quality of life in coronary heart disease patients: Analysis from a multi-wave, primary care cohort study
To determine whether a one-off, baseline measure of depression and anxiety in a primary care, coronary heart disease (CHD) population predicts ongoing symptoms, costs, and quality of life across a 3-year follow-up.Longitudinal cohort study.16 General Practice surgeries across South-East London.803 adults (70% male, mean age 71 years) contributing up to 7 follow-up points.Ongoing reporting of symptoms, health care costs, and quality of life.At baseline, 27% of the sample screened positive for symptoms of depression and anxiety, as measured by the Hospital Anxiety and Depression Scale (HADS). The probability of scoring above the cut-off throughout the follow-up was 71.5% (p<0.001) for those screening positive at baseline, and for those screening negative, the probability of scoring below the cut-off throughout the follow-up was 97.6% (p<0.001). Total health care costs were 39% higher during follow-up for those screening positive (p<0.05). Quality of life as measured by the SF-12 was lower on the mental component during follow-up for those screening positive (-0.75, CI -1.53 to 0.03, p = 0.059), and significantly lower on the physical component (-4.99, CI -6.23 to -.376, p<0.001).A one-off measure for depression and anxiety symptoms in CHD predicts future symptoms, costs, and quality of life over the subsequent three-years. These findings suggest symptoms of depression and anxiety in CHD persist throughout long periods and are detrimental to a patient's quality of life, whilst incurring higher health care costs for primary and secondary care services. Screening for these symptoms at the primary care level is important to identify and manage patients at risk of the negative effects of this comorbidity. Implementation of screening, and possible collaborative care strategies and interventions that help mitigate this risk should be the ongoing focus of researchers and policy-makers
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A Search for Dark Higgs Bosons
Recent astrophysical and terrestrial experiments have motivated the proposal
of a dark sector with GeV-scale gauge boson force carriers and new Higgs
bosons. We present a search for a dark Higgs boson using 516 fb-1 of data
collected with the BABAR detector. We do not observe a significant signal and
we set 90% confidence level upper limits on the product of the Standard
Model-dark sector mixing angle and the dark sector coupling constant.Comment: 7 pages, 5 postscript figures, published version with improved plots
for b/w printin
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