57,154 research outputs found
Breaking the Mexican Cartels: A Key Homeland Security Challenge for the Next Four Years
Although accurate statistics are hard to come by, it is quite possible that 60,000 people have died in the last six-plus years as a result of armed conflict between the Mexican cartels and the Mexican government, amongst cartels fighting each other, and as a result of cartels targeting citizens. And this figure does not even include the nearly 40,000 Americans who die each year from using illegal drugs, much of which is trafficked through the U.S.-Mexican border. The death toll is only part of the story. The rest includes the terrorist tactics used by cartels to intimidate the Mexican people and government, an emerging point of view that the cartels resemble an insurgency, the threat—both feared and realized—of danger to Americans, and the understated policy approach currently employed by the U.S. government. This short article only scratches the surface by identifying the Mexican Situation as a pressing U.S. homeland security issue requiring a renewed strategic effort by the United States over the next four years. Involving a complex web of foreign policy, law enforcement, intelligence, military, border security, drug consumption and public policy considerations, breaking the Mexican cartels is no easy feat. But it is a necessary one to secure our southern border, eliminate the presence of dangerous cartels in our cities, reduce Americans’ contribution to the drug trade and resulting violence, and play our role in restoring the Mexican citizenry to a society free from daily terror
Diffusion on random site percolation clusters. Theory and NMR microscopy experiments with model objects
Quasi two-dimensional random site percolation model objects were fabricate
based on computer generated templates. Samples consisting of two compartments,
a reservoir of HO gel attached to a percolation model object which was
initially filled with DO, were examined with NMR (nuclear magnetic
resonance) microscopy for rendering proton spin density maps. The propagating
proton/deuteron inter-diffusion profiles were recorded and evaluated with
respect to anomalous diffusion parameters. The deviation of the concentration
profiles from those expected for unobstructed diffusion directly reflects the
anomaly of the propagator for diffusion on a percolation cluster. The fractal
dimension of the random walk, , evaluated from the diffusion measurements
on the one hand and the fractal dimension, , deduced from the spin density
map of the percolation object on the other permits one to experimentally
compare dynamical and static exponents. Approximate calculations of the
propagator are given on the basis of the fractional diffusion equation.
Furthermore, the ordinary diffusion equation was solved numerically for the
corresponding initial and boundary conditions for comparison. The anomalous
diffusion constant was evaluated and is compared to the Brownian case. Some ad
hoc correction of the propagator is shown to pay tribute to the finiteness of
the system. In this way, anomalous solutions of the fractional diffusion
equation could experimentally be verified for the first time.Comment: REVTeX, 12 figures in GIF forma
Information Fusion for Assistance Systems in Production Assessment
We propose a novel methodology to define assistance systems that rely on
information fusion to combine different sources of information while providing
an assessment. The main contribution of this paper is providing a general
framework for the fusion of n number of information sources using the evidence
theory. The fusion provides a more robust prediction and an associated
uncertainty that can be used to assess the prediction likeliness. Moreover, we
provide a methodology for the information fusion of two primary sources: an
ensemble classifier based on machine data and an expert-centered model. We
demonstrate the information fusion approach using data from an industrial
setup, which rounds up the application part of this research. Furthermore, we
address the problem of data drift by proposing a methodology to update the
data-based models using an evidence theory approach. We validate the approach
using the Benchmark Tennessee Eastman while doing an ablation study of the
model update parameters.Comment: 21 Pages, 10 Figure
Engineering Bacillus megaterium for production of functional intracellular materials
Background: Over the last 10-15 years, a technology has been developed to engineer bacterial polyhydroxybutyrate (PHB) inclusions as functionalized beads, for applications such as vaccines, diagnostics and enzyme immobilization. This has been achieved by translational fusion of foreign proteins to the PHB synthase (PhaC). The respective fusion protein mediates self-assembly of PHB inclusions displaying the desired protein function. So far, beads have mainly been produced in recombinant Escherichia coli which is problematic for some applications as the lipopolysaccharides (LPS) co-purified with such inclusions are toxic to humans and animals. Results: In this study, we have engineered the formation of functional PHB inclusions in the Gram-positive bacterium Bacillus megaterium, an LPS-free and established industrial production host. As B. megaterium is a natural PHB producer, the PHB-negative strain PHA05 was used to avoid any background PHB production. Plasmid-mediated T7 promoter-driven expression of the genes encoding β-ketothiolase (phaA), acetoacetyl-CoA-reductase (phaB) and PHB synthase (phaC) enabled/effected PHB production by B. megaterium PHA05. To produce functionalized PHB inclusions, the N- and C-terminus of PhaC was fused to four and two IgG binding Z-domains from Staphylococcus aureus, respectively. The ZZ-domain PhaC fusion protein was strongly overproduced at the surface of the PHB inclusions and the corresponding isolated ZZ-domain displaying PHB beads were found to purify IgG with a binding capacity of 40-50 mg IgG/g beads. As B. megaterium has the ability to sporulate and respective endospores could co-purify with cellular inclusions, a sporulation negative production strain was generated by disrupting the spoIIE gene in PHA05. This strain did not produce spores when tested under sporulation inducing conditions and it was still able to synthesize ZZ-domain displaying PHB beads. Conclusions: This study provides proof of concept for the successful genetic engineering of B. megaterium as a host for the production of functionalized PHB beads. Disruption of the spoIIE gene rendered B. megaterium incapable of sporulation but particularly suitable for production of functionalized PHB beads. This sporulation-negative mutant represents an improved industrial production strain for biotechnological processes otherwise impaired by the possibility of endospore formation.fals
Conceptual design study for heat exhaust management in the ARC fusion pilot plant
The ARC pilot plant conceptual design study has been extended beyond its
initial scope [B. N. Sorbom et al., FED 100 (2015) 378] to explore options for
managing ~525 MW of fusion power generated in a compact, high field (B_0 = 9.2
T) tokamak that is approximately the size of JET (R_0 = 3.3 m). Taking
advantage of ARC's novel design - demountable high temperature superconductor
toroidal field (TF) magnets, poloidal magnetic field coils located inside the
TF, and vacuum vessel (VV) immersed in molten salt FLiBe blanket - this
follow-on study has identified innovative and potentially robust power exhaust
management solutions.Comment: Accepted by Fusion Engineering and Desig
Deformation effects in Ni nuclei produced in Si+Si at 112 MeV
Velocity and energy spectra of the light charged particles (protons and
-particles) emitted in the Si(E = 112 MeV) + Si
reaction have been measured at the Strasbourg VIVITRON Tandem facility. The
ICARE charged particle multidetector array was used to obtain exclusive spectra
of the light particles in the angular range 15 - 150 degree and to determine
the angular correlations of these particles with respect to the emission angles
of the evaporation residues. The experimental data are analysed in the
framework of the statistical model. The exclusive energy spectra of
-particles emitted from the Si + Si compound system are
generally well reproduced by Monte Carlo calculations using spin-dependent
level densities. This spin dependence approach suggests the onset of large
deformations at high spin. A re-analysis of previous -particle data
from the Si + Si compound system, using the same spin-dependent
parametrization, is also presented in the framework of a general discussion of
the occurrence of large deformation effects in the A ~ 60 mass region.Comment: 25 pages, 6 figure
Computational Lattice-Gas Modeling of the Electrosorption of Small Molecules and Ions
We present two recent applications of lattice-gas modeling techniques to
electrochemical adsorption on catalytically active metal substrates: urea on
Pt(100) and (bi)sulfate on Rh(111). Both involve the specific adsorption of
small molecules or ions on well-characterized single-crystal electrodes, and
they provide a particularly good fit between the adsorbate geometry and the
substrate structure. The close geometric fit facilitates the formation of
ordered submonolayer adsorbate phases in a range of electrode potential
positive of the range in which an adsorbed monolayer of hydrogen is stable. In
both systems the ordered-phase region is separated from the adsorbed- hydrogen
region by a phase transition, signified in cyclic voltammograms by a sharp
current peak. Based on data from {\it in situ\/} radiochemical surface
concentration measurements, cyclic voltammetry, and scanning tunneling micro-
scopy, and {\it ex situ\/} Auger electron spectroscopy and low-energy electron
diffraction, we have developed specific lattice-gas models for the two systems.
These models were studied by group-theoretical ground-state calcu- lations and
numerical Monte Carlo simulations, and effective lattice-gas inter- action
parameters were determined so as to provide agreement with experiments.Comment: 17 pp. uuencoded postscript, FSU-SCRI-94C-9
Oscillatory relaxation of zonal flows in a multi-species stellarator plasma
The low frequency oscillatory relaxation of zonal potential perturbations is
studied numerically in the TJ-II stellarator (where it was experimentally
detected for the first time). It is studied in full global gyrokinetic
simulations of multi-species plasmas. The oscillation frequency obtained is
compared with predictions based on single-species simulations using simplified
analytical relations. It is shown that the frequency of this oscillation for a
multi-species plasma can be accurately obtained from single-species
calculations using extrapolation formulas. The damping of the oscillation and
the influence of the different inter-species collisions is studied in detail.
It is concluded that taking into account multiple kinetic ions and electrons
with impurity concentrations realistic for TJ-II plasmas allows to account for
the values of frequency and damping rate in zonal flows relaxations observed
experimentally.Comment: 11 figures, 22 page
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