24,043 research outputs found
Satellite detection of vegetative damage and alteration caused by pollutants emitted by a zinc smelter
The author has identified the following significant results. Field observations and data collected by low flying aircraft were used to verify the accuracy of maps produced from the satellite data. Although areas of vegetation as small as six acres can accurately be detected, a white pine stand that was severely damaged by sulfur dioxide could not be differentiated from a healthy white pine stand because spectral differences were not large enough. When winter data were used to eliminate interference from herbaceous and deciduous vegetation, the damage was still undetectable. The analysis was able to produce a character map that accurately delineated areas of vegetative alteration due to high zinc levels accumulating in the soil. The map depicted a distinct gradient of less damage and alteration as the distance from the smelter increased. Although the satellite data will probably not be useful for detecting small acreages of damaged vegetation, it is concluded that the data may be very useful as an inventory tool to detect and delineate large vegetative areas possessing differing spectral signatures
European expectations of disaster information provided by critical infrastructure operators
Previous research into social media crisis communication has tended to focus on use by emergency managers rather than other key stakeholder, critical infrastructure (CI) operators. This article adds to the field by empirically investigating public expectations of information provided by CI operators during crisis situations and if CI operators currently meet such expectations. It draws on key themes that emerged from a review of the literature on public expectations of disaster related information shared via social media. Then, it presents the results of an online questionnaire and interview-based study of disaster-vulnerable communities in France, Norway, Portugal and Sweden. Results indicate that members of the public expect CI operators to provide disaster related information via traditional and social media, but not necessarily respond to their queries on social media. Operators appear to meet public expectations of traditional media use, but should expand their current practices to include digital media. Recommendations for CI operators on how to do use social media follow
Basel III Liquidity Risk Measures and Bank Failure
Basel III banking regulation emphasizes the use of liquidity coverage and nett stable funding ratios as measures of liquidity risk. In this paper, we approximate these measures by using global liquidity data for 391 hand-selected, LIBOR-based, Basel II compliant banks in 36 countries for the period 2002 to 2012. In particular, we compare the risk sensitivity of the aforementioned Basel III liquidity risk measures to those of traditional measures such as the nonperforming assets ratio, return-on-assets, LIBOR-OISS, Basel II Tier 1 capital ratio, government securities ratio, and brokered deposits ratio. Furthermore, we use a discrete-time hazard model to study bank failure. In this regard, we find that Basel III risk measures have limited ability to predict bank failure when compared with their traditional counterparts. An important result is that a higher liquidity coverage ratio is associated with a higher bank failure rate. We also find that market-wide liquidity risk (proxied by LIBOR-OISS) was the major predictor of bank failures in 2009 and 2010 while idiosyncratic liquidity risk (proxied by other liquidity risk measures) was less. In particular, our contribution is the first to achieve these results on a global scale over a relatively long period for a variety of banks
Some triviality results for quasi-Einstein manifolds and Einstein warped products
In this paper we prove a number of triviality results for Einstein warped
products and quasi-Einstein manifolds using different techniques and under
assumptions of various nature. In particular we obtain and exploit gradient
estimates for solutions of weighted Poisson-type equations and adaptations to
the weighted setting of some Liouville-type theorems.Comment: 15 pages, fixed minor mistakes in Section
A new neurosurgical tool incorporating differential geometry and cellular automata techniques
Using optical coherence imaging, it is possible to visualize seizure progression intraoperatively. However, it is difficult to pinpoint an exact epileptic focus. This is crucial in attempts to minimize the amount of resection necessary during surgical therapeutic interventions for epilepsy and is typically done approximately from visual inspection of optical coherence imaging stills. In this paper, we create an algorithm with the potential to pinpoint the source of a seizure from an optical coherence imaging still. To accomplish this, a grid is overlaid on optical coherence imaging stills. This then serves as a grid for a two-dimensional cellular automation. Each cell is associated with a Riemannian curvature tensor representing the curvature of the brain's surface in all directions for a cell. Cells which overlay portions of the image which show neurons that are firing are considered "depolarized"
Sediment Microbiomes Associated with Critical Habitat of the Juvenile American Horseshoe Crab; Limulus Polyphemus
Plumb Beach, Brooklyn, New York in USA is an important horseshoe crab breeding and nursery ground that has experienced substantial anthropogenic influence, including pollution, erosion and subsequent restoration. Since little is known about the relationship between sediment microbial communities and juvenile horseshoe crab survival, next generation sequencing was used to characterize and compare the sediment microbiome of three distinct areas of Plumb Beach:- a tidal creek with abundant juveniles, East Beach with moderate number of juveniles, and West Beach- a highly disturbed area where juvenile crabs are rarely seen. The microbiome of juvenile crab intestinal content (both dissected gut content and fecal flush content) from the tidal creek site was also examined. The results showed that in our 2017 survey, the overall dominant sediment orders at all beach sites were Vibrionales (30%), Flavobacteriales (22%) and Alteromonadales (21%). Although alpha diversity was similar among the three beach sites, Bray-Curtis distances assessed by Permanova revealed significant differences in Beta diversity, with a unique microbial assemblage found in the tidal creek. Both crab gut and fecal flush samples did not sequence well, showing low species diversity and very high variability. This study is the first to use next generation sequencing to characterize Plumb Beach sediment microbes and the first attempt to examine the gut microbiome of juvenile horseshoe crabs. This information will contribute to understanding the relationships between sediment microbial assemblages and juvenile crab populations within this important urban habitat
Four New Delta Scuti Pulsators from a Variability Survey of 131 Stars
In a photometric variability survey of 131 stars with B < 14 mag, we have
found four new Delta Scuti stars. We were sensitive to oscillation amplitudes
as low as a few mmag. The detection rate of short-period (P < 0.1 d) pulsating
variable stars, which may be relevant for planned large variability surveys
such as GAIA, POI, and even the LSST, was therefore 3%. All four new variable
stars have low pulsation amplitude (tens of mmag), and one has a very short
period (0.0198 d). This star is one of the fastest known Delta Scuti pulsators.
The short period of this variable star makes it observationally tractable, and
it may therefore be a particularly good candidate for asteroseismological
studies. All four new variable stars will add to the cadre of low-amplitude and
relatively short-period Delta Scuti stars that are potentially useful for
learning about the structure of stars on or near the main sequence, slightly
more massive than the Sun.Comment: To appear in the June 2002 issue of PASP, 9 pages, 6 figure
Fully integrated transport approach to heavy ion reactions with an intermediate hydrodynamic stage
We present a coupled Boltzmann and hydrodynamics approach to relativistic
heavy ion reactions. This hybrid approach is based on the Ultra-relativistic
Quantum Molecular Dynamics (UrQMD) transport approach with an intermediate
hydrodynamical evolution for the hot and dense stage of the collision.
Event-by-event fluctuations are directly taken into account via the
non-equilibrium initial conditions generated by the initial collisions and
string fragmentations in the microscopic UrQMD model. After a (3+1)-dimensional
ideal hydrodynamic evolution, the hydrodynamical fields are mapped to hadrons
via the Cooper-Frye equation and the subsequent hadronic cascade calculation
within UrQMD proceeds to incorporate the important final state effects for a
realistic freeze-out. This implementation allows to compare pure microscopic
transport calculations with hydrodynamic calculations using exactly the same
initial conditions and freeze-out procedure. The effects of the change in the
underlying dynamics - ideal fluid dynamics vs. non-equilibrium transport theory
- will be explored. The freeze-out and initial state parameter dependences are
investigated for different observables. Furthermore, the time evolution of the
baryon density and particle yields are discussed. We find that the final pion
and proton multiplicities are lower in the hybrid model calculation due to the
isentropic hydrodynamic expansion while the yields for strange particles are
enhanced due to the local equilibrium in the hydrodynamic evolution. The
results of the different calculations for the mean transverse mass excitation
function, rapidity and transverse mass spectra for different particle species
at three different beam energies are discussed in the context of the available
data.Comment: 20 pages, 21 figures, 1 additional figure, minor corrections and
revised figures for clarity, version published in PR
Inhomogeneous LOFF phase revisited for surface superconductivity
We consider 2D surface superconductivity in high magnetic fields parallel to
the surface. We demonstrate that the spin-orbit interaction at the surface
changes the properties of the inhomogeneous superconducting
Larkin-Ovchinnikov-Fulde-Ferrell state that develops above fields given by the
paramagnetic criterion. Strong spin-orbit interaction significantly broadens
the range of existence of the LOFF phase, which takes the form of periodic
superconducting stripes running along the field direction on the surface,
leading to the anisotropy of its properties. In connection with experiments by
J.H. Schon et al. [Nature 914, 434 (2001)] on superconductivity of electrically
doped films of the cuprate material CaCuO2, we also discuss this problem for
the d-wave pairing to indicate the possibility of a re-orientation transition
as the magnetic field direction is rotated in the plane parallel to the
surface. Our results provide a tool for studying surface superconductivity as a
function of doping.Comment: 4 pages, 1 fig, revtex
Hydrodynamic modeling of deconfinement phase transition in nuclear collisions
The (3+1)-dimensional ideal hydrodynamics is used to simulate collisions of
gold nuclei with bombarding energies from 1 to 160 GeV per nucleon. The initial
state is represented by two cold Lorentz-boosted nuclei. Two equations of
state: with and without the deconfinement phase transition are used. We have
investigated dynamical trajectories of compressed baryon-rich matter as
functions of various thermodynamical variables. The parameters of collective
flow and hadronic spectra are calculated. It is shown that presence of the
deconfinement phase transition leads to increase of the elliptic flow and to
flattening of proton rapidity distributions.Comment: 11 pages, 6 figure
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