1,719 research outputs found
Predicting reservoir hosts and arthropod vectors from evolutionary signatures in RNA virus genomes
Identifying the animal origins of RNA viruses requires years of field and laboratory studies that stall responses to emerging infectious diseases. Using large genomic and ecological datasets, we demonstrate that animal reservoirs and the existence and identity of arthropod vectors can be predicted directly from viral genome sequences via machine learning. We illustrate the ability of these models to predict the epidemiology of diverse viruses across most human-infective families of single-stranded RNA viruses, including 69 viruses with previously elusive or never-investigated reservoirs or vectors. Models such as these, which capitalize on the proliferation of low-cost genomic sequencing, can narrow the time lag between virus discovery and targeted research, surveillance, and management
Far infrared and submillimeter brightness temperatures of the giant planets
The brightness temperatures of Jupiter, Saturn, Uranus, and Neptune in the range 35 to 1000 micron. The effective temperatures derived from the measurements, supplemented by shorter wavelength Voyager data for Jupiter and Saturn, are 126.8 + or - 4.5 K, 93.4 + or - 3.3 K, 58.3 + or - 2.0 K, and 60.3 + or - 2.0 K, respectively. The implications of the measurements for bolometric output and for atmospheric structure and composition are discussed. The temperature spectrum of Jupiter shows a strong peak at approx. 350 microns followed by a deep valley at approx. 450 to 500 microns. Spectra derived from model atmospheres qualitatively reproduced these features but do not fit the data closely
The Origin of Nitrogen on Jupiter and Saturn from the N/N Ratio
The Texas Echelon cross Echelle Spectrograph (TEXES), mounted on NASA's
Infrared Telescope Facility (IRTF), was used to map mid-infrared ammonia
absorption features on both Jupiter and Saturn in February 2013. Ammonia is the
principle reservoir of nitrogen on the giant planets, and the ratio of
isotopologues (N/N) can reveal insights into the molecular
carrier (e.g., as N or NH) of nitrogen to the forming protoplanets, and
hence the source reservoirs from which these worlds accreted. We targeted two
spectral intervals (900 and 960 cm) that were relatively clear of
terrestrial atmospheric contamination and contained close features of
NH and NH, allowing us to derive the ratio from a single
spectrum without ambiguity due to radiometric calibration (the primary source
of uncertainty in this study). We present the first ground-based determination
of Jupiter's N/N ratio (in the range from to
), which is consistent with both previous space-based studies
and with the primordial value of the protosolar nebula. On Saturn, we present
the first upper limit on the N/N ratio of no larger than
for the 900-cm channel and a less stringent
requirement that the ratio be no larger than for the
960-cm channel ( confidence). Specifically, the data rule out
strong N-enrichments such as those observed in Titan's atmosphere and in
cometary nitrogen compounds. To the extent possible with ground-based
radiometric uncertainties, the saturnian and jovian N/N ratios
appear indistinguishable, implying that N-enriched ammonia ices could
not have been a substantial contributor to the bulk nitrogen inventory of
either planet, favouring the accretion of primordial N from the gas phase
or as low-temperature ices.Comment: 33 pages, 19 figures, manuscript accepted for publication in Icaru
Observational constraints on the atmospheres of Uranus and Neptune from new measurements near 10 micron
Uranus was detected at 10.3, 11.6 and 12.5 micrometers approximately 1 micrometer spectral bandpasses, with respective brightness temperatures of 74.0 + 0.9 or -1.1, 67.6 + 0.5 or -0.7, and 65.5 + 0.6 or -0.7 K and the first detection of Neptune at 10.3 micrometers with a brightness temperature of 77.5 + 0.7 or -0.9 K. We also detected Neptune at 11.36 micrometers with 2% spectral resolution at 81.0 + 0.8 or -0.9 K. The 10 micrometers continuous of both Uranus and Neptune may in part be due to reflected solar radiation as well as thermal emission. If all of the observed flux is reflected light, then the maximum geometric albedo of Uranus is 0.115 + or - 0.020, and that of Neptune is 0.229 + or - 0.043. In the context of previous observations in this region, the maximum stratospheric C2H6 mixing ratio is found to be 3 x 10 to the -8 power for Uranus and 3 x 10 to the -6 power for Neptune. A value for the maximum mixing ratio in the stratosphere of Neptune on the order of 1 - 0.004 appears to be consistent with the available data
Connecting Localism and Community Empowerment: Research Review and Critical Synthesis for the AHRC Connected Community Programme
The Connecting Localism and Community Empowerment project sought to assess the merits of the assumption that localisms brings about community empowerment through a review of the existing academic and policy literatures. The key findings from the review point towards a lack of clarity and coherence in the literature in the usage and interpretations of the terms ‗localism‘ and ‗community empowerment‘. They are often defined by implication or tacitly assumed to have an accepted definition. Whilst greater localism is generally claimed to increase community empowerment, there are substantive grounds for questioning this claim, which arise from critically analysing these concepts and how they interact. These grounds highlight conditions which need to be fulfilled if localism is to realise its potential to enhance community empowerment. To understand these conditions we analysed four international case studies. We also consider two assessments of the New Labour government‘s localist policies in the UK
Two-year observations of the Jupiter polar regions by JIRAM on board Juno
We observed the evolution of Jupiter's polar cyclonic structures over two years between February 2017 and February 2019, using polar observations by the Jovian InfraRed Auroral Mapper, JIRAM, on the Juno mission. Images and spectra were collected by the instrument in the 5‐μm wavelength range. The images were used to monitor the development of the cyclonic and anticyclonic structures at latitudes higher than 80° both in the northern and the southern hemispheres. Spectroscopic measurements were then used to monitor the abundances of the minor atmospheric constituents water vapor, ammonia, phosphine and germane in the polar regions, where the atmospheric optical depth is less than 1. Finally, we performed a comparative analysis with oceanic cyclones on Earth in an attempt to explain the spectral characteristics of the cyclonic structures we observe in Jupiter's polar atmosphere
Evaluation of modelling approaches for predicting the spatial distribution of soil organic carbon stocks at the national scale
Soil organic carbon (SOC) plays a major role in the global carbon budget. It
can act as a source or a sink of atmospheric carbon, thereby possibly
influencing the course of climate change. Improving the tools that model the
spatial distributions of SOC stocks at national scales is a priority, both for
monitoring changes in SOC and as an input for global carbon cycles studies. In
this paper, we compare and evaluate two recent and promising modelling
approaches. First, we considered several increasingly complex boosted
regression trees (BRT), a convenient and efficient multiple regression model
from the statistical learning field. Further, we considered a robust
geostatistical approach coupled to the BRT models. Testing the different
approaches was performed on the dataset from the French Soil Monitoring
Network, with a consistent cross-validation procedure. We showed that when a
limited number of predictors were included in the BRT model, the standalone BRT
predictions were significantly improved by robust geostatistical modelling of
the residuals. However, when data for several SOC drivers were included, the
standalone BRT model predictions were not significantly improved by
geostatistical modelling. Therefore, in this latter situation, the BRT
predictions might be considered adequate without the need for geostatistical
modelling, provided that i) care is exercised in model fitting and validating,
and ii) the dataset does not allow for modelling of local spatial
autocorrelations, as is the case for many national systematic sampling schemes
EVOLUTION OF THE STRATOSPHERIC TEMPERATURE AND CHEMICAL COMPOSITION OVER ONE TITANIAN YEAR
Since the Voyager 1 (V1) flyby in 1980, Titans exploration from space and the ground has been ongoing for more than a full revolution of Saturn around the Sun (one Titan year or 29.5 Earth years was completed in May 2010). In this study we search for temporal variations affecting Titans atmospheric thermal and chemical structure within that year. We process Cassini CIRS data taken during the Titan flybys from 2006-2013 and compare them to the 1980 V1IRIS spectra (re-analyzed here). We also consider data from Earth-based and -orbiting observatories (such as from the ISO, re-visited). When we compare the CIRS 2010 and the IRIS data we find limited inter-annual variations, below the 25 or35 levels for the lower and middle, or the high latitudes, respectively. A return to the 1980 stratospheric temperatures and abundances is generally achieved from 50degN to 50degS, indicative of the solar radiation being the dominating energy source at 10 AU, as for the Earth, as predicted by GCM and photochemical models. However, some exceptions exist among the most complex hydrocarbons (C4H2 and C3H4), especially in the North. In the Southern latitudes, since 2012, we see a trend for an increase of several trace gases, possibly indicative of a seasonal atmospheric reversal. At the Northern latitudes we found enhanced abundances around the period of the northern spring equinox in mid-2009 (as in Bampasidis et al. 2012), which subsequently decreased (from 2010-2012) returning to values similar to those found in the V1 epoch a Titanian year before
Space shuttle low pressure auxiliary propulsion subsystem design definition Subtask A report
Space shuttle low pressure, hydrogen oxygen auxiliary propulsion subsystem requirements, tradeoffs, and concept selectio
Moderate Resolution Spitzer Infrared Spectrograph (IRS) Observations of M, L, and T Dwarfs
We present 10 - 19 um moderate resolution spectra of ten M dwarfs, one L
dwarf, and two T dwarf systems obtained with the Infrared Spectrograph (IRS)
onboard the Spitzer Space Telescope. The IRS allows us to examine molecular
spectroscopic features/lines at moderate spectral resolution in a heretofore
untapped wavelength regime. These R~600 spectra allow for a more detailed
examination of clouds, non-equilibrium chemistry, as well as the molecular
features of H2O, NH3, and other trace molecular species that are the hallmarks
of these objects. A cloud-free model best fits our mid-infrared spectrum of the
T1 dwarf epsilon Indi Ba, and we find that the NH3 feature in epsilon Indi Bb
is best explained by a non-equilibrium abundance due to vertical transport in
its atmosphere. We examined a set of objects (mostly M dwarfs) in multiple
systems to look for evidence of emission features, which might indicate an
atmospheric temperature inversion, as well as trace molecular species; however,
we found no evidence of either.Comment: 19 pages, 7 figures, accepted ApJ 1/12/0
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