714 research outputs found
Hypogenic Speleogenesis within Seven Rivers Evaporites: Coffee Cave, Eddy County, New Mexico
Coffee Cave, located in the lower Pecos region of southeastern New Mexico, illustrates processes of hypogenic speleogenesis in the middle Permian Seven Rivers Formation. Coffee Cave is a rectilinear gypsum maze cave with at least four stratigraphically-distinct horizons of development. Morphological features throughout the cave provide unequivocal evidence of hypogenic ascending speleogenesis in a confined aquifer system driven by mixed (forced and free) convection. Morphologic features in individual cave levels include a complete suite that defines original rising flow paths, ranging from inlets for hypogenic fluids (feeders) through transitional forms (rising wall channels) to ceiling half-tube flow features and fluid outlets (cupolas and exposed overlying beds). Passage morphology does not support origins based on epigenic processes and lateral development, although the presence of fine-grained sediments in the cave suggests minimal overprinting by backflooding. Feeder distributions show a lateral shift in ascending fluids, with decreasing dissolutional development in upper levels. It is likely that additional hypogenic karst phenomena are present in the vicinity of Coffee Cave because regional hydrologic conditions are optimum for confined speleogenesis, with artesian discharge still active in the region
The Pecos River Hypogene Speleogenetic Province: a Basin-Scale Karst Paradigm for Eastern New Mexico and West Texas, USA
Since the mid-Tertiary, lateral migration and entrenchment of the Pecos River Valley in eastern New Mexico and west Texas, USA, has significantly influenced regional groundwater flow paths, providing a focus for ascending flow in multi-storey artesian systems and a powerful potentiometric driving force for hypogene speleogenesis. Individual occurrences of hypogene karst phenomena associated with the central Pecos River Valley are widespread throughout the greater Delaware Basin region, including development in a wide range of Permian carbonate and evaporate fades. Hypogene occurrences are well-documented as far north as Santa Rosa, New Mexico and as far south as Lake Amistad, Texas. Throughout the northern shelf, intrastratal dissolution and brecciation of the San Andres formation is widespread as a result of eastward migration of the Pecos River. Proximal to the current river, hypogene dissolution in interbedded carbonate/evaporite facies of the Seven Rivers Formation has produced three-dimensional network caves and vertical collapse structures. In the carbonate reeffacies of the Guadalupe Mountains, complex three dimensional caves are common, as well as stepped terraces associated with eastward migration of thePecos River. Although these caves have been attributed to sulfuric acid dissolution, they are the result of hypogene speleogenesis in which solutional aggressivity was increased by the addition of both thermal and sulfuric-acid components. Within the interior of the Delaware Basin, hypogene karst in basin-filling evaporite facies of the Castile and Salado Formations is widespread, including development of large solution subsidence troughs associated with the lateral migration of the Pecos River. On the far eastern margin of the Delaware Basin, at the southeastern tip of the Central Basin Platform, persistent down cutting of the Pecos River Valley contributed to the development of hypogene karst within the Yates Petroleum Field, providing cavernous reservoir porosity for the largest individual oil field known within the Permian Basin region. Immediately below the confluence of the Pecos River and the Rio Grande, the large first order magnitude spring, Goodenough Spring, flows from a deep phreatic cave under extreme artesian conditions, even as 45 meters of pressure head has been added over the spring from Amistad Reservoir
Measuring Statistical Isotropy of CMB Anisotropy
The statistical expectation values of the temperature fluctuations and
polarization of cosmic microwave background (CMB) are assumed to be preserved
under rotations of the sky. We investigate the statistical isotropy (SI) of the
CMB maps recently measured by the Wilkinson Microwave Anisotropy Probe (WMAP)
using the bipolar spherical harmonic formalism proposed in Hajian & Souradeep
2003 for CMB temperature anisotropy and extended to CMB polarization in Basak,
Hajian & Souradeep 2006. The Bipolar Power Spectrum (BiPS) had been measured
for the full sky CMB anisotropy maps of the first year WMAP data and now for
the recently released three years of WMAP data. We also introduce and measure
directional sensitive reduced Bipolar coefficients on the three year WMAP ILC
map. Consistent with our published results from first year WMAP data we have no
evidence for violation of statistical isotropy on large angular scales.
Preliminary analysis of the recently released first WMAP polarization maps,
however, indicate significant violation of SI even when the foreground
contaminated regions are masked out. Further work is required to confirm a
possible cosmic origin and rule out the (more likely) origin in observational
artifact such as foreground residuals at high galactic latitude.Comment: 12 pages, 3 figures; Proceedings of the Fundamental Physics With CMB
workshop, UC Irvine, March 23-25, 2006, to be published in New Astronomy
Review
Water Uptake by Evaporating pMDI Aerosol Prior to Inhalation Affects Both Regional and Total Deposition in the Respiratory System
© 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/)As pulmonary drug deposition is a function of aerosol particle size distribution, it is critical that the dynamics of particle formation and maturation in pMDI sprays in the interim between generation and inhalation are fully understood. This paper presents an approach to measure the evaporative and condensational fluxes of volatile components and water from and to solution pMDI droplets following generation using a novel technique referred to as the Single Particle Electrodynamic Lung (SPEL). In doing so, evaporating aerosol droplets are shown capable of acting as condensation nuclei for water. Indeed, we show that the rapid vaporisation of volatile components from a volatile droplet is directly correlated to the volume of water taken up by condensation. Furthermore, a significant volume of water is shown to condense on droplets of a model pMDI formulation (hydrofluoroalkane (HFA), ethanol and glycerol) during evaporative droplet ageing, displaying a dramatic shift from a core composition of a volatile species to that of predominantly water (non-volatile glycerol remained in this case). This yields a droplet with a water activity of 0.98 at the instance of inhalation. The implications of these results on regional and total pulmonary drug deposition are explored using the International Commission of Radiological Protection (ICRP) deposition model, with an integrated semi-analytical treatment of hygroscopic growth. Through this, droplets with water activity of 0.98 upon inhalation are shown to produce markedly different dose deposition profiles to those with lower water activities at the point of inspiration.Peer reviewe
No large-angle correlations on the non-Galactic microwave sky
We investigate the angular two-point correlation function of temperature in
the WMAP maps. Updating and extending earlier results, we confirm the lack of
correlations outside the Galaxy on angular scales greater than about 60 degrees
at a level that would occur in 0.025 per cent of realizations of the
concordance model. This represents a dramatic increase in significance from the
original observations by the COBE-DMR and a marked increase in significance
from the first-year WMAP maps. Given the rest of the reported angular power
spectrum C_\ell, the lack of large-angle correlations that one infers outside
the plane of the Galaxy requires covariance among the C_\ell up to \ell=5.
Alternately, it requires both the unusually small (5 per cent of realizations)
full-sky large-angle correlations, and an unusual coincidence of alignment of
the Galaxy with the pattern of cosmological fluctuations (less than 2 per cent
of those 5 per cent). We argue that unless there is some undiscovered
systematic error in their collection or reduction, the data point towards a
violation of statistical isotropy. The near-vanishing of the large-angle
correlations in the cut-sky maps, together with their disagreement with results
inferred from full-sky maps, remain open problems, and are very difficult to
understand within the concordance model.Comment: 9 pages, 2 figures, updated with corrections in published versio
Should we doubt the cosmological constant?
While Bayesian model selection is a useful tool to discriminate between
competing cosmological models, it only gives a relative rather than an absolute
measure of how good a model is. Bayesian doubt introduces an unknown benchmark
model against which the known models are compared, thereby obtaining an
absolute measure of model performance in a Bayesian framework. We apply this
new methodology to the problem of the dark energy equation of state, comparing
an absolute upper bound on the Bayesian evidence for a presently unknown dark
energy model against a collection of known models including a flat LambdaCDM
scenario. We find a strong absolute upper bound to the Bayes factor B between
the unknown model and LambdaCDM, giving B < 3. The posterior probability for
doubt is found to be less than 6% (with a 1% prior doubt) while the probability
for LambdaCDM rises from an initial 25% to just over 50% in light of the data.
We conclude that LambdaCDM remains a sufficient phenomenological description of
currently available observations and that there is little statistical room for
model improvement.Comment: 10 pages, 2 figure
CMB Anomalies from Imperfect Dark Energy: Confrontation with the Data
We test anisotropic dark energy models with the 7-year WMAP temperature
observations data. In the presence of imperfect sources, due to large-scale
gradients or anisotropies in the dark energy field, the CMB sky will be
distorted anisotropically on its way to us by the ISW effect. The signal
covariance matrix then becomes nondiagonal for small multipoles, but at the anisotropy is negligible. We parametrize possible violations of
rotational invariance in the late universe by the magnitude of a
post-Friedmannian deviation from isotropy and its scale dependence. This allows
to obtain hints on possible imperfect nature of dark energy and the large-angle
anomalous features in the CMB. A robust statistical analysis, subjected to
various tests and consistency checks, is performed to compare the predicted
correlations with those obtained from the satellite-measured CMB full sky maps.
The preferred axis point towards and the
amplitude of the anisotropy is (1 deviation
quoted). The best-fit model has a steep blue anisotropic spectrum
().Comment: 11 pages, 4 figure
Large Scale Traces of Solar System Cold Dust on CMB Anisotropies
We explore the microwave anisotropies at large angular scales produced by the
emission from cold and large dust grains, expected to exist in the outer parts
of the Solar System, using a simple toy model for this diuse emission. Its
amplitude is constrained in the Far-IR by the COBE data and is compatible with
simulations found in the literature. We analyze the templates derived after
subtracting our model from the WMAP ILC 7 yr maps and investigate on the
cosmological implications of such a possible foreground. The anomalies related
to the low quadrupole of the angular power spectrum, the two-point correlation
function, the parity and the excess of signal found in the ecliptic plane are
significantly alleviated. An impact of this foreground for some cosmological
parameters characterizing the spectrum of primordial density perturbations,
relevant for on-going and future CMB anisotropy experiments, is found.Comment: Issue 2.0, Accepted for pub. in MNRAS, Apr 8th, 2011, (sub. Oct 4th,
2010); 10 pages, 6 Figures, 1 table; pdflatex with mn2e, AMS, natbib,
txfonts, graphic
A search for concentric rings with unusual variance in the 7-year WMAP temperature maps using a fast convolution approach
We present a method for the computation of the variance of cosmic microwave
background (CMB) temperature maps on azimuthally symmetric patches using a fast
convolution approach. As an example of the application of the method, we show
results for the search for concentric rings with unusual variance in the 7-year
WMAP data. We re-analyse claims concerning the unusual variance profile of
rings centred at two locations on the sky that have recently drawn special
attention in the context of the conformal cyclic cosmology scenario proposed by
Penrose (2009). We extend this analysis to rings with larger radii and centred
on other points of the sky. Using the fast convolution technique enables us to
perform this search with higher resolution and a wider range of radii than in
previous studies. We show that for one of the two special points rings with
radii larger than 10 degrees have systematically lower variance in comparison
to the concordance LambdaCDM model predictions. However, we show that this
deviation is caused by the multipoles up to order l=7. Therefore, the deficit
of power for concentric rings with larger radii is yet another manifestation of
the well-known anomalous CMB distribution on large angular scales. Furthermore,
low variance rings can be easily found centred on other points in the sky. In
addition, we show also the results of a search for extremely high variance
rings. As for the low variance rings, some anomalies seem to be related to the
anomalous distribution of the low-order multipoles of the WMAP CMB maps. As
such our results are not consistent with the conformal cyclic cosmology
scenario.Comment: 12 pages, 11 figures, 1 table. Published in MNRAS. This research was
supported by the Agence Nationale de la Recherche (ANR-08-CEXC-0002-01
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