79 research outputs found
Report and preliminary results of R/V POSEIDON cruise POS500, LISA, Ligurian Slope AUV mapping, gravity coring and seismic reflection, Catania (Italy) – Malaga (Spain), 25.05.2016 – 09.06.2016
Cruise POS500 “LISA” with R/V Poseidon studied the western Ligurian Margin off
Southern France, an area in the northeastern part of the western Mediterranean Sea
characterized by its active tectonism and frequent mass wasting. The region near the Var
estuary close to the city of Nice is particularly suited for landslide research because it
represents a natural laboratority where it is possible to study a series of trigger processes of
geological and anthropogenic origin. The aim of this MARUM expedition was to:
i. Study fresh water seepage in the marine Nice airport landslide and adjacent stable
plateau in 15-50 m water depth using water sampling, CTD and geochemistry;
ii. Recover and deploy a number of observatories that monitor, pressure, temperature, tilt
and seismicity;
iii. Run an AUV micro-bathymetric survey with MARUM AUV SEAL5000 to
complement existing multibeam maps; and
iv. Acquire additional high-resolution seismic reflection profiles to unravel the complex
architecture of the Nice slope and Var delta.
In a period of approximately two weeks, we acquired valuable geophysical information that
helps to understand the evolution of this portion of the Ligurian Margin and further to
support an active Amphibious Drilling proposal submitted to ICDP and IODP. We could
also show that heavy spring rainfall plus melt water from the French Maritime Alps supplied
sufficient hydraulic forcing to push Var aquifer groundwaters to seep into the marine
deposits and water column. Freshening was strongest in the 1979 Nice landslide scar, but
was also found at the outer edge of the shelf. Recovery and redeployment of various
observatory prototypes worked well, both for the MARUM MeBo seafloor drillstring tolos
and independent piezometers.
Observatory data have yet to be evaluated. In addition, geochemical analyses of bottom
waters and pore waters was deferred to shore-based laboratorios except for salinity estimates
using a refractometer. Seismic processing was started onboard, but is largely taking place
post-cruise at University Bremen
Highly dispersed PTFE/Co3O4 flexible films as photocatalyst showing fast kinetic performance for the discoloration of azo-dyes under solar irradiation
Small nanosized clusters of Co3O4 coated on PTFE (polytetrafluoroethylene) flexible film is reported as a novel supported photocatalyst effective in the fast discoloration of the azo-dye Orange II under simulated solar radiation in the presence of oxone (2KHSO5·KHSO4·K2SO4). The photocatalytic discoloration of Orange II on the PTFE/Co3O4 films proceeds within minutes and the process could be repeated many times without a loss in photocatalyst stability. The photodiscoloration proceeds with a photonic efficiency of ∼1. The PTFE seems to act as a structure forming matrix for the colloidal Co3O4 coated on it surface leading to nanosized clusters of Co3O4. Monitoring the amount of Co2+-ions shows the Co2+-ions from the PTFE/Co3O4 during the photocatalysis enter the solution and at a later are stage re-adsorbed the Co3O4 crystallographic network (∼8 min). By elemental analysis (EA) the loading of Co-loading per cm2 PTFE film was found to vary between 1% and 2%. Transmission electron microscopy (TEM) shows the size of the Co3O4 clusters to vary between 3 and 10 nm. Electron dispersive spectrometry (EDS) confirms the presence of Co on the PTFE. X-ray photoelectron spectroscopy (XPS) of the PTFE/Co3O4 films reveal a partial reduction of the Co3O4 after Orange II discoloration leading to a substantial increase of the amount of Co(II) species in the Co3O4. Physical insight is provided into the catalyst film surface by carrying out Ar-sputtering of the PTFE/Co3O4 surface to remove the catalyst overlayers up to ∼20 nm
Thermodynamics of lattice QCD with two light quark flavours on a 16^3 x 8 lattice II
We have extended our earlier simulations of the high temperature behaviour of
lattice QCD with two light flavours of staggered quarks on a
lattice to lower quark mass (m_q=0.00625). The transition from hadronic matter
to a quark-gluon plasma is observed at corresponding to a
temperature of MeV. We present measurements of observables
which probe the nature of the quark-gluon plasma and serve to distinguish it
from hadronic matter. Although the transition is quite abrupt, we have seen no
indications that it is first order.Comment: 23 pages, RevteX, 6 encapsulated postscript figure
Hadron Spectrum in QCD with Valence Wilson Fermions and Dynamical Staggered Fermions at $6/g^2=5.6
We present an analysis of hadronic spectroscopy for Wilson valence quarks
with dynamical staggered fermions at lattice coupling at
sea quark mass and 0.025, and of Wilson valence quarks in quenched
approximation at and 5.95, both on lattices. We
make comparisons with our previous results with dynamical staggered fermions at
the same parameter values but on lattices doubled in the temporal
direction.Comment: 32 page
Simple Matrix Elements with Dynamical Fermions
We report on studies of simple matrix elements from simulations with two
flavors of sea quarks, both staggered and Wilson. We show the decay constants
of vector and pseudoscalar mesons. The effects of sea quarks are small. These
simulations are done at relatively large lattice spacing compared to most
quenched studies.Comment: 4 page uuencoded postscript poster session for Lattice 93,
COLO-HEP-33
Effects of spatial size, lattice doubling and source operator on the hadron spectrum with dynamical staggered quarks
We have extended our previous study of the lattice QCD spectrum with 2
flavors of staggered dynamical quarks at and and 0.01
to larger lattices, with better statistics and with additional sources for the
propagators. The additional sources allowed us to estimate the mass
and to measure the masses of all mesons whose operators are local in time.
These mesons show good evidence for flavor symmetry restoration, except for the
masses of the Goldstone and non-Goldstone pions. PCAC is observed in that
, and is estimated. Use of undoubled lattices
removes problems with the pion propagator found in our earlier work. Previously
we found a large change in the nucleon mass at a quark mass of when
we increased the spatial size from 12 to 16. No such effect is observed at the
larger quark mass, . Two kinds of wall source were used, and we
have found difficulties in getting consistent results for the nucleon mass
between the two sources.Comment: 30 pages PostScript fil
Preparation, stabilization and characterization of TiO2 on thin polyethylene films (LDPE): Photocatalytic applications
An innovative way to fix preformed nanocrystalline TiO2 on low-density polyethylene film (LDPE-TiO2) is presented. The LDPE-TiO2 film was able to mediate the complete photodiscoloration of Orange II using about seven times less catalyst than a TiO2 suspension and proceeded with a photonic efficiency of ~0.02. The catalyst shows photostability over long operational periods during the photodiscoloration of the azo dye Orange II. The LDPE-TiO2 catalyst leads to full dye discoloration under simulated solar light but only to a 30% TOC reduction since long-lived intermediates generated in solution seem to preclude full mineralization of the dye. Physical insight is provided into the mechanism of stabilization of the LDPE-TiO2 composite during the photocatalytic process by X-ray photoelectron spectroscopy (XPS). The adherence of TiO2 on LDPE is investigated by electron microscopy (EM) and atomic force microscopy (AFM). The thickness of the TiO2 film is seen to vary between 1.25 and 1.69 mm for an unused LDPE-TiO2 film and between 1.31 and 1.50 mmfor a sample irradiated 10h during Orange II discoloration pointing out to a higher compactness of the TiO2 film after the photocatalysis
The Effective Electroweak Chiral Lagrangian: The Matter Sector
We parametrize in a model-independent way possible departures from the
minimal Standard Model predictions in the matter sector. We only assume the
symmetry breaking pattern of the Standard Model and that new particles are
sufficiently heavy so that the symmetry is non-linearly realized. Models with
dynamical symmetry breaking are generically of this type. We review in the
effective theory language to what extent the simplest models of dynamical
breaking are actually constrained and the assumptions going into the comparison
with experiment. Dynamical symmetry breaking models can be approximated at
intermediate energies by four-fermion operators. We present a complete
classification of the latter when new particles appear in the usual
representations of the group as well as a partial
classification in the general case. We discuss the accuracy of the four-fermion
description by matching to a simple `fundamental' theory. The coefficients of
the effective lagrangian in the matter sector for dynamical symmetry breaking
models (expressed in terms of the coefficients of the four-quark operators) are
then compared to those of models with elementary scalars (such as the minimal
Standard Model). Contrary to a somewhat widespread belief, we see that the sign
of the vertex corrections is not fixed in dynamical symmetry breaking models.
This work provides the theoretical tools required to analyze, in a rather
general setting, constraints on the matter sector of the Standard Model.Comment: Latex, 45 pages, 8 eps figures. Sections 5, 6 and 9 have been
rewritten to clarify the contents. Some mistakes and typos have been
corrected. Two references have been added. Figures 7 and 8 have been modifie
Discrete approaches to quantum gravity in four dimensions
The construction of a consistent theory of quantum gravity is a problem in
theoretical physics that has so far defied all attempts at resolution. One
ansatz to try to obtain a non-trivial quantum theory proceeds via a
discretization of space-time and the Einstein action. I review here three major
areas of research: gauge-theoretic approaches, both in a path-integral and a
Hamiltonian formulation, quantum Regge calculus, and the method of dynamical
triangulations, confining attention to work that is strictly four-dimensional,
strictly discrete, and strictly quantum in nature.Comment: 33 pages, invited contribution to Living Reviews in Relativity; the
author welcomes any comments and suggestion
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