334 research outputs found
The Rio Grande Rise and Jean Charcot Seamount Chain - microcontinents or the trail of the Tristan-Gough hotspot? Cruise No. MSM 82, 18 March 2019 - 24 April 2019, Montevideo (Uruguay) - Montevideo (Uruguay), RIOGRANDE
Rio Grande Rise: microcontinent, mantle plume, or both? The origin of the Rio Grande Rise (RGR) is debated. It could represent a continental sliver, or a large igneous province that was emplaced in the late Cretaceous after the opening of the South Atlantic Ocean. The interplay between the RGR and the nearby Jean Charcot Seamount Chain (JCSC) is also not understood. Cruise MSM82 dredge sampled rocks from the JCSC and the RGR and measured two seismic refraction profiles across the RGR where it is bisected by a long rift graben. A range of geophysical data were also collected during much of the expedition, including magnetics, gravity, bathymetry (Kongsberg EM 122), sub-bottom profiling (ATLAS PARASOUND DS P70) and ADCP data. The combination of geochronological, geochemical and geophysical information will provide a unique window on the relation between mantle plumes, continental fragments and the evolution of large igneous provinces
The complex relationship of exposure to new Plasmodium infections and incidence of clinical malaria in Papua New Guinea
The molecular force of blood-stage infection (molFOB) is a
quantitative surrogate metric for malaria transmission at
population level and for exposure at individual level.
Relationships between molFOB, parasite prevalence and clinical
incidence were assessed in a treatment-to-reinfection cohort,
where P.vivax (Pv) hypnozoites were eliminated in half the
children by primaquine (PQ). Discounting relapses, children
acquired equal numbers of new P. falciparum (Pf) and Pv
blood-stage infections/year (Pf-molFOB = 0-18, Pv-molFOB = 0-23)
resulting in comparable spatial and temporal patterns in
incidence and prevalence of infections. Including relapses,
Pv-molFOB increased >3 fold (relative to PQ-treated children)
showing greater heterogeneity at individual (Pv-molFOB = 0-36)
and village levels. Pf- and Pv-molFOB were strongly associated
with clinical episode risk. Yearly Pf clinical incidence rate
(IR = 0.28) was higher than for Pv (IR = 0.12) despite lower
Pf-molFOB. These relationships between molFOB, clinical
incidence and parasite prevalence reveal a comparable decline in
Pf and Pv transmission that is normally hidden by the high
burden of Pv relapses. CLINICAL TRIAL REGISTRATION:
ClinicalTrials.gov NCT02143934
Changes in organic carbon to clay ratios in different soils and land uses in England and Wales over time
Realistic targets for soil organic carbon (SOC) concentrations are needed, accounting for differences between soils and land uses. We assess the use of SOC/clay ratio for this purpose by comparing changes over time in (a) the National Soil Inventory of England and Wales, first sampled in 1978â1983 and resampled in 1994â2003, and (b) two long-term experiments under ley-arable rotations on contrasting soils in the East of England. The results showed that normalising for clay concentration provides a more meaningful separation between land uses than changes in SOC alone. Almost half of arable soils in the NSI had degraded SOC/clay ratios (â1/8, respectively. Given the wide range of soils and land uses across England and Wales in the datasets used to test these targets, they should apply across similar temperate regions globally, and at national to sub-regional scales.Biotechnology and Biological Sciences Research Council (BBSRC): BBS/E/C/000I0310 and BBS/E/C/000 J0300. Lawes Agricultural Trus
Comparing the effect of different sample conditions and spectral libraries on the prediction accuracy of soil properties from near- and mid-infrared spectra at the field-scale
The prediction accuracy of soil properties by proximal soil sensing has made their application more practical. However, in order to gain sufficient accuracy, samples are typically air-dried and milled before spectral measurements are made. Calibration of the spectra is usually achieved by making wet chemistry measurements on a subset of the field samples and local regression models fitted to aid subsequent prediction. Both sample handling and wet chemistry can be labour and resource intensive. This study aims to quantify the uncertainty associated with soil property estimates from different methods to reduce effort of field-scale calibrations of soil spectra. We consider two approaches to reduce these expenses for predictions made from visible-near-infrared ((V)NIR), mid-infrared (MIR) spectra and their combination. First, we considered reducing the level of processing of the samples by comparing the effect of different sample conditions (in-situ, unprocessed, air-dried and milled). Second, we explored the use of existing spectral libraries to inform calibrations (based on milled samples from the UK National Soil Inventory) with and without âspikingâ the spectral libraries with a small subset of samples from the study fields. Prediction accuracy of soil organic carbon, pH, clay, available P and K for each of these approaches was evaluated on samples from agricultural fields in the UK. Available P and K could only be moderately predicted with the field-scale dataset where samples were milled. Therefore this study found no evidence to suggest that there is scope to reduce costs associated with sample processing or field-scale calibration for available P and K. However, the results showed that there is potential to reduce time and cost implications of using (V)NIR and MIR spectra to predict soil organic carbon, clay and pH. Compared to field-scale calibrations from milled samples, we found that reduced sample processing lowered the ratio of performance to inter-quartile range (RPIQ) between 0% and 76%. The use of spectral libraries reduced the RPIQ of predictions relative to field-scale calibrations from milled samples between 54% and 82% and the RPIQ was reduced between 29% and 70% for predictions when spectral libraries were spiked. The increase in uncertainty was specific to the combination of soil property and sensor analysed. We conclude that there is always a trade-off between prediction accuracy and the costs associated with soil sampling, sample processing and wet chemical analysis. Therefore the relative merits of each approach will depend on the specific case in question
Axisymmetric Radiative Transfer Models of Kilonovae
The detailed observations of GW170817 proved for the first time directly that
neutron star mergers are a major production site of heavy elements. The
observations could be fit by a number of simulations that qualitatively agree,
but can quantitatively differ (e.g. in total r-process mass) by an order of
magnitude. We categorize kilonova ejecta into several typical morphologies
motivated by numerical simulations, and apply a radiative transfer Monte Carlo
code to study how the geometric distribution of the ejecta shapes the emitted
radiation. We find major impacts on both spectra and light curves. The peak
bolometric luminosity can vary by two orders of magnitude and the timing of its
peak by a factor of five. These findings provide the crucial implication that
the ejecta masses inferred from observations around the peak brightness are
uncertain by at least an order of magnitude. Mixed two-component models with
lanthanide-rich ejecta are particularly sensitive to geometric distribution. A
subset of mixed models shows very strong viewing angle dependence due to
lanthanide "curtaining," which persists even if the relative mass of
lanthanide-rich component is small. The angular dependence is weak in the rest
of our models, but different geometric combinations of the two components lead
to a highly diverse set of light curves. We identify geometry-dependent {P
Cygni} features in late spectra that directly map out strong lines in the
simulated opacity of neodymium, which can help to constrain the ejecta geometry
and to directly probe the r-process abundances.Comment: 23 pages, 18 figures; accepted to Ap
Catching Element Formation In The Act
Gamma-ray astronomy explores the most energetic photons in nature to address
some of the most pressing puzzles in contemporary astrophysics. It encompasses
a wide range of objects and phenomena: stars, supernovae, novae, neutron stars,
stellar-mass black holes, nucleosynthesis, the interstellar medium, cosmic rays
and relativistic-particle acceleration, and the evolution of galaxies. MeV
gamma-rays provide a unique probe of nuclear processes in astronomy, directly
measuring radioactive decay, nuclear de-excitation, and positron annihilation.
The substantial information carried by gamma-ray photons allows us to see
deeper into these objects, the bulk of the power is often emitted at gamma-ray
energies, and radioactivity provides a natural physical clock that adds unique
information. New science will be driven by time-domain population studies at
gamma-ray energies. This science is enabled by next-generation gamma-ray
instruments with one to two orders of magnitude better sensitivity, larger sky
coverage, and faster cadence than all previous gamma-ray instruments. This
transformative capability permits: (a) the accurate identification of the
gamma-ray emitting objects and correlations with observations taken at other
wavelengths and with other messengers; (b) construction of new gamma-ray maps
of the Milky Way and other nearby galaxies where extended regions are
distinguished from point sources; and (c) considerable serendipitous science of
scarce events -- nearby neutron star mergers, for example. Advances in
technology push the performance of new gamma-ray instruments to address a wide
set of astrophysical questions.Comment: 14 pages including 3 figure
Study of the decay
The decay is studied
in proton-proton collisions at a center-of-mass energy of TeV
using data corresponding to an integrated luminosity of 5
collected by the LHCb experiment. In the system, the
state observed at the BaBar and Belle experiments is
resolved into two narrower states, and ,
whose masses and widths are measured to be where the first uncertainties are statistical and the second
systematic. The results are consistent with a previous LHCb measurement using a
prompt sample. Evidence of a new
state is found with a local significance of , whose mass and width
are measured to be and , respectively. In addition, evidence of a new decay mode
is found with a significance of
. The relative branching fraction of with respect to the
decay is measured to be , where the first
uncertainty is statistical, the second systematic and the third originates from
the branching fractions of charm hadron decays.Comment: All figures and tables, along with any supplementary material and
additional information, are available at
https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2022-028.html (LHCb
public pages
Measurement of the ratios of branching fractions and
The ratios of branching fractions
and are measured, assuming isospin symmetry, using a
sample of proton-proton collision data corresponding to 3.0 fb of
integrated luminosity recorded by the LHCb experiment during 2011 and 2012. The
tau lepton is identified in the decay mode
. The measured values are
and
, where the first uncertainty is
statistical and the second is systematic. The correlation between these
measurements is . Results are consistent with the current average
of these quantities and are at a combined 1.9 standard deviations from the
predictions based on lepton flavor universality in the Standard Model.Comment: All figures and tables, along with any supplementary material and
additional information, are available at
https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2022-039.html (LHCb
public pages
Robust estimation of bacterial cell count from optical density
Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data
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