108 research outputs found
XAS study of the local environment of impurities in doped TiO2 thin films
In this work we present an X-ray Absorption Spectroscopy characterization of
the local environment of the impurity in room temperature ferromagnetic anatase
TiO2 thin films doped with Co, Ni, Cu, or Zn, deposited on LaAlO3 substrate by
Pulsed Laser Deposition. It was found that there is a considerable amount of
impurity atoms substituting Ti in TiO2 anatase, although the presence of metal
transition monoxide clusters can not be discarded. From our results we infer
that the observed room temperature ferromagnetism of the samples could be
assigned to the metal transition atoms replacing Ti in TiO2 anatase.Comment: 4 pages, 3 figures, 1 table, Physica B (in press
Quantum Oscillation Studies of the Fermi Surface of LaFePO
We review recent experimental measurements of the Fermi surface of the
iron-pnictide superconductor LaFePO using quantum oscillation techniques. These
studies show that the Fermi surface topology is close to that predicted by
first principles density functional theory calculations, consisting of
quasi-two-dimensional electron-like and hole-like sheets. The total volume of
the two hole sheets is almost equal to that of the two electron sheets, and the
hole and electron Fermi surface sheets are close to a nesting condition. No
evidence for the predicted three dimensional pocket arising from the Fe
band is found. Measurements of the effective mass suggest a
renormalisation of around two, close to the value for the overall band
renormalisation found in recent angle resolved photoemission measurements.Comment: Submitted to Physica C special issue on iron-pnictide superconductor
Will a rising sea sink some estuarine wetland ecosystems?
Sea-level rise associatedwith climate change presents amajor challenge to plant diversity and ecosystemservice
provision in coastal wetlands. In this study,we investigate the effect of sea-level rise on benthos, vegetation, and
ecosystem diversity in a tidal wetland in westWales, the UK. Present relationships between plant communities
and environmental variableswere investigated through 50 plots atwhich vegetation (species and coverage), hydrological
(surface or groundwater depth, conductivity) and soil (matrix chroma, presence or absence ofmottles,
organic content, particle size) data were collected. Benthic communities were sampled at intervals along a continuum
from saline to freshwater. To ascertain future changes to the wetlands' hydrology, a GIS-based empirical
model was developed. Using a LiDAR derived land surface, the relative effect of peat accumulation and rising sea
levels were modelled over 200 years to determine how frequently portions of the wetland will be inundated by
mean sea level, mean high water spring and mean high water neap conditions. The model takes into account
changing extents of peat accumulation as hydrological conditions alter.
Model results show that changes to the wetland hydrology will initially be slow. However, changes in frequency
and extent of inundation reach a tipping point 125 to 175 years from2010 due to the extremely low slope of the
wetland. From then onwards, large portions of the wetland become flooded at every flood tide and saltwater intrusion
becomes more common. This will result in a reduction in marsh biodiversity with plant communities
switching toward less diverse and occasionally monospecific communities that are more salt tolerant.IS
Induction of immune response in broiler chickens immunized with recombinant FliC and challenged by Salmonella Typhimurium
On the sensitivity of the HAWC observatory to gamma-ray bursts
We present the sensitivity of HAWC to Gamma Ray Bursts (GRBs). HAWC is a very
high-energy gamma-ray observatory currently under construction in Mexico at an
altitude of 4100 m. It will observe atmospheric air showers via the water
Cherenkov method. HAWC will consist of 300 large water tanks instrumented with
4 photomultipliers each. HAWC has two data acquisition (DAQ) systems. The main
DAQ system reads out coincident signals in the tanks and reconstructs the
direction and energy of individual atmospheric showers. The scaler DAQ counts
the hits in each photomultiplier tube (PMT) in the detector and searches for a
statistical excess over the noise of all PMTs. We show that HAWC has a
realistic opportunity to observe the high-energy power law components of GRBs
that extend at least up to 30 GeV, as it has been observed by Fermi LAT. The
two DAQ systems have an energy threshold that is low enough to observe events
similar to GRB 090510 and GRB 090902b with the characteristics observed by
Fermi LAT. HAWC will provide information about the high-energy spectra of GRBs
which in turn could help to understanding about e-pair attenuation in GRB jets,
extragalactic background light absorption, as well as establishing the highest
energy to which GRBs accelerate particles
Using human induced pluripotent stem cells to treat retinal disease
AbstractThe eye is an ideal target for exploiting the potential of human induced pluripotent stem cell (hiPSC) technology in order to understand disease pathways and explore novel therapeutic strategies for inherited retinal disease. The aim of this article is to map the pathway from state-of-the art laboratory-based discoveries to realising the translational potential of this emerging technique. We describe the relevance and routes to establishing hiPSCs in selected models of human retinal disease. Additionally, we define pathways for applying hiPSC technology in treating currently incurable, progressive and blinding retinal disease
New Blood Pressure-Associated Loci Identified in Meta-Analyses of 475,000 Individuals
Background - Genome-wide association studies have recently identified >400 loci that harbor DNA sequence variants that influence blood pressure (BP). Our earlier studies identified and validated 56 single nucleotide variants (SNVs) associated with BP from meta-analyses of exome chip genotype data. An additional 100 variants yielded suggestive evidence of association. Methods and Results - Here, we augment the sample with 140 886 European individuals from the UK Biobank, in whom 77 of the 100 suggestive SNVs were available for association analysis with systolic BP or diastolic BP or pulse pressure. We performed 2 meta-analyses, one in individuals of European, South Asian, African, and Hispanic descent (pan-ancestry, ≈475 000), and the other in the subset of individuals of European descent (≈423 000). Twenty-one SNVs were genome-wide significant (P<5×10-8) for BP, of which 4 are new BP loci: rs9678851 (missense, SLC4A1AP), rs7437940 (AFAP1), rs13303 (missense, STAB1), and rs1055144 (7p15.2). In addition, we identified a potentially independent novel BP-associated SNV, rs3416322 (missense, SYNPO2L) at a known locus, uncorrelated with the previously reported SNVs. Two SNVs are associated with expression levels of nearby genes, and SNVs at 3 loci are associated with other traits. One SNV with a minor allele frequency <0.01, (rs3025380 at DBH) was genome-wide significant. Conclusions - We report 4 novel loci associated with BP regulation, and 1 independent variant at an established BP locus. This analysis highlights several candidate genes with variation that alter protein function or gene expression for potential follow-up
A MODEST review
We present an account of the state of the art in the fields explored by the
research community invested in 'Modeling and Observing DEnse STellar systems'.
For this purpose, we take as a basis the activities of the MODEST-17
conference, which was held at Charles University, Prague, in September 2017.
Reviewed topics include recent advances in fundamental stellar dynamics,
numerical methods for the solution of the gravitational N-body problem,
formation and evolution of young and old star clusters and galactic nuclei,
their elusive stellar populations, planetary systems, and exotic compact
objects, with timely attention to black holes of different classes of mass and
their role as sources of gravitational waves.
Such a breadth of topics reflects the growing role played by collisional
stellar dynamics in numerous areas of modern astrophysics. Indeed, in the next
decade, many revolutionary instruments will enable the derivation of positions
and velocities of individual stars in the Milky Way and its satellites and will
detect signals from a range of astrophysical sources in different portions of
the electromagnetic and gravitational spectrum, with an unprecedented
sensitivity. On the one hand, this wealth of data will allow us to address a
number of long-standing open questions in star cluster studies; on the other
hand, many unexpected properties of these systems will come to light,
stimulating further progress of our understanding of their formation and
evolution.Comment: 42 pages; accepted for publication in 'Computational Astrophysics and
Cosmology'. We are much grateful to the organisers of the MODEST-17
conference (Charles University, Prague, September 2017). We acknowledge the
input provided by all MODEST-17 participants, and, more generally, by the
members of the MODEST communit
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