19,525 research outputs found
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Assimilating the Martian water cycle
Water ice clouds have been shown to alter the thermal structure of the Martian atmosphere. Here we discuss the assimilation of total column water vapour and dust optical depth data from the Thermal Emission Spectrometer (TES) into the UK/LMD MGCM, and compare the predictions of cloud and temperature in the assimilation with observations
Detouring the Tax Reform Act of 1976: Tax Shelter Proprietorships
After briefly reviewing the so-called abusive aspects of tax shelters which led Congress to enact the Tax Reform Act of 1976, the authors focus on an unintended loophole-the tax shelter proprietorship. The tax shelter proprietorship remains a viable method of reducing federal income taxes payable by high bracket taxpayers. The business mechanics and tax aspects of a sound recording proprietorship are analyzed and specific suggestions for future reforms to deal with the problem of tax shelter proprietorships are delineated
Improved simulation of non-Gaussian temperature and polarization CMB maps
We describe an algorithm to generate temperature and polarization maps of the
cosmic microwave background radiation containing non-Gaussianity of arbitrary
local type. We apply an optimized quadrature scheme that allows us to predict
and control integration accuracy, speed up the calculations, and reduce memory
consumption by an order of magnitude. We generate 1000 non-Gaussian CMB
temperature and polarization maps up to a multipole moment of l_max = 1024. We
validate the method and code using the power spectrum and the fast cubic
(bispectrum) estimator and find consistent results. The simulations are
provided to the community.Comment: 18 pages, 19 figures. Accepted for publication in ApJS. Simulations
can be obtained at http://planck.mpa-garching.mpg.de/cmb/fnl-simulation
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Data assimilation of three mars years of thermal emission spectrometer observations: Large-scale transient and stationary waves
Introduction: Large-scale traveling and stationary planetary waves are diagnosed from an analysis of profiles retrieved from the Thermal Emission Spectrometer (TES) [1] aboard the Mars Global Surveyor (MGS) spacecraft during its scientific mapping phase. The analysis was conducted by assimilating the TES temperature profile and total dust opacity retrievals [2] into a pseudo-spectral Mars general circulation model to produce a full, physically self consistent record of all atmospheric variables stored at an interval of two hours over the entire MGS mapping phase. The data cover a period of about three Mars years, corresponding to the interval 1999тАУ2004 on Earth. These include the year which contained the 2001 global dust storm [3] and two years of more moderate dust activity, although large regional storms occurred during southern hemisphere summer in both years and there was considerable atmospheric variability between all three years [4].
We focus on the planetary wave activity, both traveling and stationary large-scale waves, in the assimilated record. Data assimilation is a particularly useful technique for the analysis of transient wave behaviour since it is capable of producing global, time-dependent atmospheric fields, which the assimilation scheme endeavours to make as consistent as possible with whatever observations are available. These atmospheric variables may be sampled from the model as often as desired, on a regular grid of points. If particular variables, or regions of the atmosphere, are not observed directly, the model will at least ensure that they are consistent with the laws of physics incorporated within its framework.
A complex climatology of transient waves is revealed, modulated by the large-scale topography and surface thermal properties, the time of year and, crucially, the amount of dust suspended in the atmosphere. Some individual case studies show the temporal and spatial structures of the waves in the assimilation record, although the large data set has by no means been fully explored. Companion papers discuss the thermal atmospheric tides [5] and the processes associated with the initiation of dust storms [6] from the same assimilated analysis. Output from the same assimilation has also been used to identify potential deficiencies in the model, such as the lack of water ice clouds [7]
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Data assimilation for the Martian atmosphere using MGS Thermal Emission Spectrometer observations
From the introduction: Given the quantity of data expected from current and forthcoming spacecraft missions to Mars, it is now possible to use data assimilation as a means of atmospheric analysis for the first time for a planet other than the Earth. Several groups have described plans to develop assimilation schemes for Mars [Banfield et al., 1995; Houben, 1999; Lewis and Read, 1995; Lewis et al., 1996, 1997; Zhang et al., 2001]. Data assimilation is a technique for the analysis of atmospheric observations which combines currently valid information with prior knowledge from previous observations and dynamical and physical constraints, via the use of a numerical model. Despite the number of new missions, observations of the atmosphere of Mars in the near future are still likely to be sparse when compared to those of the Earth, perhaps
comprising one orbiter and a few surface stations at best
at any one time. Data assimilation is useful as a means
to extract the maximum information from such observations,
both by a form of interpolation in space and time
using model constraints and by the combination of information from different observations, e.g. temperature
profiles and surface pressure measurements which may
be irregularly distributed. The procedure can produce a
dynamically consistent set of meteorological fields and
can be used directly to test and to refine an atmospheric
model against observations
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Assimilation of TES data from the Mars Global Surveyor scientifc mapping phase
The Thermal Emission Spectrometer (TES)aboard Mars Global Surveyor has produced data which cover almost two Martian years so far (during its scientific mapping phase). Thermal profiles for the atmosphere below 40 km and total dust opacities can be retrieved from TES nadir spectra and assimilated into a Mars general circulation model (MGCM), by using the assimilation techniques described in detail by Lewis et al. (2002). This paper describes some preliminary results from assimilations of temperature data from the period Ls=141┬░- 270┬░ corresponding to late northern summer until winter solstice on Mars. Work in progress is devoted to assimilate both temperature and total dust opacity data for the full period for which they are already available
Mass-varying neutrino in light of cosmic microwave background and weak lensing
We aim to constrain mass-varying neutrino models using large scale structure
observations and produce forecast for the Euclid survey. We investigate two
models with different scalar field potential and both positive and negative
coupling parameters \beta. These parameters correspond to growing or decreasing
neutrino mass, respectively. We explore couplings up to |\beta|<5. In the case
of the exponential potential, we find an upper limit on <0.004
at 2- level. In the case of the inverse power law potential the null
coupling can be excluded with more than 2-\sigma significance; the limits on
the coupling are \beta>3 for the growing neutrino mass and \beta<-1.5 for the
decreasing mass case. This is a clear sign for a preference of higher
couplings. When including a prior on the present neutrino mass the upper limit
on the coupling becomes |\beta|<3 at 2- level for the exponential
potential. Finally, we present a Fisher forecast using the tomographic weak
lensing from an Euclid-like experiment and we also consider the combination
with the cosmic microwave background (CMB) temperature and polarisation spectra
from a Planck-like mission. If considered alone, lensing data is more efficient
in constraining with respect to CMB data alone. There is, however,
a strong degeneracy in the \beta- plane. When the two data sets
are combined, the latter degeneracy remains, but the errors are reduced by a
factor ~2 for both parameters.Comment: 5 pages, 6 figures. Now published in A&A 500, 657-665 (2009
Trauma-informed care in the UK:where are we? A qualitative study of health policies and professional perspectives
BACKGROUND: Trauma-informed (TI) approach is a framework for a system change intervention that transforms the organizational culture and practices to address the high prevalence and impact of trauma on patients and healthcare professionals, and prevents re-traumatization in healthcare services. Review of TI approaches in primary and community mental healthcare identified limited evidence for its effectiveness in the UK, however it is endorsed in various policies. This study aimed to investigate the UK-specific context through exploring how TI approaches are represented in health policies, and how they are understood and implemented by policy makers and healthcare professionals. METHODS: A qualitative study comprising of a document analysis of UK health policies followed by semi-structured interviews with key informants with direct experience of developing and implementing TI approaches. We used the Ready Extract Analyse Distil (READ) approach to guide policy document review, and the framework method to analyse data. RESULTS: We analysed 24 documents and interviewed 11 professionals from healthcare organizations and local authorities. TI approach was included in national, regional and local policies, however, there was no UK- or NHS-wide strategy or legislation, nor funding commitment. Although documents and interviews provided differing interpretations of TI care, they were aligned in describing the integration of TI principles at the system level, contextual tailoring to each organization, and addressing varied challenges within health systems. TI care in the UK has had piecemeal implementation, with a nation-wide strategy and leadership visible in Scotland and Wales and more disjointed implementation in England. Professionals wanted enhanced coordination between organizations and regions. We identified factors affecting implementation of TI approaches at the level of organization (leadership, service user involvement, organizational culture, resource allocation, competing priorities) and wider context (government support, funding). Professionals had conflicting views on the future of TI approaches, however all agreed that government backing is essential for implementing policies into practice. CONCLUSIONS: A coordinated, more centralized strategy and provision for TI healthcare, increased funding for evaluation, and education through professional networks about evidence-based TI health systems can contribute towards evidence-informed policies and implementation of TI approaches in the UK. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12913-022-08461-w
The shape of the CMB lensing bispectrum
Lensing of the CMB generates a significant bispectrum, which should be
detected by the Planck satellite at the 5-sigma level and is potentially a
non-negligible source of bias for f_NL estimators of local non-Gaussianity. We
extend current understanding of the lensing bispectrum in several directions:
(1) we perform a non-perturbative calculation of the lensing bispectrum which
is ~10% more accurate than previous, first-order calculations; (2) we
demonstrate how to incorporate the signal variance of the lensing bispectrum
into estimates of its amplitude, providing a good analytical explanation for
previous Monte-Carlo results; and (3) we discover the existence of a
significant lensing bispectrum in polarization, due to a previously-unnoticed
correlation between the lensing potential and E-polarization as large as 30% at
low multipoles. We use this improved understanding of the lensing bispectra to
re-evaluate Fisher-matrix predictions, both for Planck and cosmic variance
limited data. We confirm that the non-negligible lensing-induced bias for
estimation of local non-Gaussianity should be robustly treatable, and will only
inflate f_NL error bars by a few percent over predictions where lensing effects
are completely ignored (but note that lensing must still be accounted for to
obtain unbiased constraints). We also show that the detection significance for
the lensing bispectrum itself is ultimately limited to 9 sigma by cosmic
variance. The tools that we develop for non-perturbative calculation of the
lensing bispectrum are directly relevant to other calculations, and we give an
explicit construction of a simple non-perturbative quadratic estimator for the
lensing potential and relate its cross-correlation power spectrum to the
bispectrum. Our numerical codes are publicly available as part of CAMB and
LensPix.Comment: 32 pages, 10 figures; minor changes to match JCAP-accepted version.
CMB lensing and primordial local bispectrum codes available as part of CAMB
(http://camb.info/
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