197 research outputs found
Toxicity of Oil Slicks to Arctic Amphipods
A study was conducted to measure the toxicity of oil spills to Arctic amphipods. Exposure to oil resulted in death, especially if animals physically entered the slicks. Arctic diesel was more toxic than Prudhoe crude oil. Toxicity of Prudhoe crude oil was associated with the paraffinic and aromatic components. Exposure to the tarry asphaltic fraction of crude oil did not result in amphipod mortality
Introduction to the Workshop on Ecological Effects of Hydrocarbon Spills in Alaska
With continued development of Arctic petroleum reserves there has been growing interest in the fate and effects of petroleum hydrocarbons that may be spilled in northern environments. ... There have been a number of studies made during the past decade on the ecological effects of hydrocarbon spillage in the Arctic areas .... [This article offers an overview of some of the research undertaken on this subject since 1970.
Atrial natriuretic factor
The discovery of the first well-defined natriuretic hormone, the Atrial Natriuretic Factor (ANF), has prompted research on its impact on volume regulation in health and disease. The natriuretic, diuretic, and smooth muscle-relaxing properties suggest an important role of this novel hormone in pathophysiological states with sodium or volume retention, such as congestive heart failure or cirrhosis of the liver. Investigations on the implications of ANF in liver disease have been performed for little more than 1 year, and results are still controversial in many respects. At present, it seems very likely that there is no absolute deficiency of plasma ANF in patients with cirrhosis. Moreover, elevated plasma levels in cirrhotics with ascites have been reported by several groups. However, as yet, a molecular characterization of this increased immunoreactivity is still lacking. There is disagreement on the reduced release of and renal response to ANF in subgroups of cirrhotics; however, stimulus-response-coupling might be impaired. Further studies are needed to elucidate the pathophysiological implications and therapeutical potential of ANF in patients with chronic liver disease
Aspects of CP violation in the HZZ coupling at the LHC
We examine the CP-conserving (CPC) and CP-violating (CPV) effects of a
general HZZ coupling through a study of the process H -> ZZ* -> 4 leptons at
the LHC. We construct asymmetries that directly probe these couplings. Further,
we present complete analytical formulae for the angular distributions of the
decay leptons and for some of the asymmetries. Using these we have been able to
identify new observables which can provide enhanced sensitivity to the CPV coupling. We also explore probing CP violation through shapes of
distributions in different kinematic variables, which can be used for Higgs
bosons with mH < 2 mZ.Comment: 36 pages, 17 figures, LaTeX, version accepted for publicatio
Multiple Interactions and the Structure of Beam Remnants
Recent experimental data have established some of the basic features of
multiple interactions in hadron-hadron collisions. The emphasis is therefore
now shifting, to one of exploring more detailed aspects. Starting from a brief
review of the current situation, a next-generation model is developed, wherein
a detailed account is given of correlated flavour, colour, longitudinal and
transverse momentum distributions, encompassing both the partons initiating
perturbative interactions and the partons left in the beam remnants. Some of
the main features are illustrated for the Tevatron and the LHC.Comment: 69pp, 33 figure
Probing exotic phenomena at the interface of nuclear and particle physics with the electric dipole moments of diamagnetic atoms: A unique window to hadronic and semi-leptonic CP violation
The current status of electric dipole moments of diamagnetic atoms which
involves the synergy between atomic experiments and three different theoretical
areas -- particle, nuclear and atomic is reviewed. Various models of particle
physics that predict CP violation, which is necessary for the existence of such
electric dipole moments, are presented. These include the standard model of
particle physics and various extensions of it. Effective hadron level combined
charge conjugation (C) and parity (P) symmetry violating interactions are
derived taking into consideration different ways in which a nucleon interacts
with other nucleons as well as with electrons. Nuclear structure calculations
of the CP-odd nuclear Schiff moment are discussed using the shell model and
other theoretical approaches. Results of the calculations of atomic electric
dipole moments due to the interaction of the nuclear Schiff moment with the
electrons and the P and time-reversal (T) symmetry violating
tensor-pseudotensor electron-nucleus are elucidated using different
relativistic many-body theories. The principles of the measurement of the
electric dipole moments of diamagnetic atoms are outlined. Upper limits for the
nuclear Schiff moment and tensor-pseudotensor coupling constant are obtained
combining the results of atomic experiments and relativistic many-body
theories. The coefficients for the different sources of CP violation have been
estimated at the elementary particle level for all the diamagnetic atoms of
current experimental interest and their implications for physics beyond the
standard model is discussed. Possible improvements of the current results of
the measurements as well as quantum chromodynamics, nuclear and atomic
calculations are suggested.Comment: 46 pages, 19 tables and 16 figures. A review article accepted for
EPJ
Probing SUSY CP Violation in Two-Body Stop Decays at the LHC
We study CP asymmetries in two-body decays of top squarks into neutralinos
and sleptons at the LHC. These asymmetries are used to probe the CP phases
possibly present in the stop and neutralino sector of the Minimal
Supersymmetric Standard Model. Taking into account bounds from experimental
electric dipole moment searches, we identify areas in the mSUGRA parameter
space where CP asymmetries can be sizeable and discuss the feasibility of their
observation at the LHC. As a result, potentially detectable CP asymmetries in
stop decays at the LHC are found, motivating further detailed experimental
studies for probing SUSY CP phases.Comment: 38 pages, 13 figures, error in Yukawa coupling corrected, revised
benchmark scenario and figures, JHEP versio
Updated Reach of the CERN LHC and Constraints from Relic Density, b->s gamma and a(mu) in the mSUGRA Model
{We present an updated assessment of the reach of the CERN LHC pp collider
for supersymmetric matter in the context of the minimal supergravity (mSUGRA)
model. In addition to previously examined channels, we also include signals
with an isolated photon or with a leptonically decaying Z boson. For an
integrated luminosity of 100 fb^{-1}, values of m_{1/2}\sim 1400 GeV can be
probed for small m_0, corresponding to a gluino mass of m_{\tg}\sim 3 TeV. For
large m_0, in the hyperbolic branch/focus point region, m_{1/2}\sim 700 GeV can
be probed, corresponding to m_{\tg}\sim 1800 GeV. We also map out parameter
space regions preferred by the measured values of the dark matter relic
density, the b\to s\gamma decay rate, and the muon anomalous magnetic moment
a_\mu, and discuss how SUSY might reveal itself in these regions. We find the
CERN LHC can probe the entire stau co-annihilation region and also most of the
heavy Higgs annihilation funnel allowed by WMAP data, except for some range of
large m_0 and m_{1/2} if \tan\beta \agt 50.Comment: 22 page latex file including 10 EPS figures; bug fix in relic density
code modifies figures in co-annihilation regio
Will a rising sea sink some estuarine wetland ecosystems?
Sea-level rise associatedwith climate change presents amajor challenge to plant diversity and ecosystemservice
provision in coastal wetlands. In this study,we investigate the effect of sea-level rise on benthos, vegetation, and
ecosystem diversity in a tidal wetland in westWales, the UK. Present relationships between plant communities
and environmental variableswere investigated through 50 plots atwhich vegetation (species and coverage), hydrological
(surface or groundwater depth, conductivity) and soil (matrix chroma, presence or absence ofmottles,
organic content, particle size) data were collected. Benthic communities were sampled at intervals along a continuum
from saline to freshwater. To ascertain future changes to the wetlands' hydrology, a GIS-based empirical
model was developed. Using a LiDAR derived land surface, the relative effect of peat accumulation and rising sea
levels were modelled over 200 years to determine how frequently portions of the wetland will be inundated by
mean sea level, mean high water spring and mean high water neap conditions. The model takes into account
changing extents of peat accumulation as hydrological conditions alter.
Model results show that changes to the wetland hydrology will initially be slow. However, changes in frequency
and extent of inundation reach a tipping point 125 to 175 years from2010 due to the extremely low slope of the
wetland. From then onwards, large portions of the wetland become flooded at every flood tide and saltwater intrusion
becomes more common. This will result in a reduction in marsh biodiversity with plant communities
switching toward less diverse and occasionally monospecific communities that are more salt tolerant.IS
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