886 research outputs found
Theoretical study of ferroelectric nanoparticles using phase reconstructed electron microscopy
Development of an effective outsourcing strategy for toxicological studies in the chemical industry
The chemical industry has been put under considerable time pressure by the European Community Regulation REACH (Registration, Evaluation, and Authorization of Chemicals). The work outlined here has been developed at the BASF SEâs Experimental Toxicology and Ecology Unit with the objective of promoting a faster reaction to the testing demand generated by the new legislation. A considerable increase in forecasted demand for tests has created the necessity to increase the Toxicology Unitâs outsourcing activities. The first goal was to optimize the selection and management process of Contract Research Organizations (CROs), so that toxicological studies can be performed with minimal risk while maximizing quality and cost advantage. A second objective was to develop performance measurement system in form of a balanced scorecard to evaluate contracting efficiency by monitoring major drivers in the outsourcing process to ensure the alignment between strategic objectives and actual performance.<br
Computed Tomography Imaging in Simulated Ongoing Cardiopulmonary Resuscitation: No Need to Switch Off the Chest Compression Device during Image Acquisition
Computed tomography (CT) represents the current standard for imaging of patients with acute life-threatening diseases. As some patients present with circulatory arrest, they require cardiopulmonary resuscitation. Automated chest compression devices are used to continue resuscitation during CT examinations, but tend to cause motion artifacts degrading diagnostic evaluation of the chest. The aim was to investigate and evaluate a CT protocol for motion-free imaging of thoracic structures during ongoing mechanical resuscitation. The standard CT trauma protocol and a CT protocol with ECG triggering using a simulated ECG were applied in an experimental setup to examine a compressible thorax phantom during resuscitation with two different compression devices. Twenty-eight phantom examinations were performed, 14 with AutoPulse and 14 with corpuls cpr. With each device, seven CT examinations were carried out with ECG triggering and seven without. Image quality improved significantly applying the ECG-triggered protocol (p < 0.001), which allowed almost artifact-free chest evaluation. With the investigated protocol, radiation exposure was 5.09% higher (15.51 mSv vs. 14.76 mSv), and average reconstruction time of CT scans increased from 45 to 76 s. Image acquisition using the proposed CT protocol prevents thoracic motion artifacts and facilitates diagnosis of acute life-threatening conditions during continuous automated chest compression
Circadian rhythm of hepatic cytosolic and nuclear estrogen receptors
The distribution of estrogen receptor between the cytosolic and nuclear compartments were evaluated in liver of male rats to determine whether a circadian rhythm exists. Cytosolic receptor reached a maximum level at 400 hours and a minimum at 2000 and 2400 hr. Nuclear receptor reached a maximum level at 800 hr and was lowest at 1600 and 2000 hr. Serum estradiol levels were also highest at 800 hr and lowest at 1600 hr. The variations in cytosolic and nuclear receptors are not reciprocal; in fact, the overall content of receptor in the liver is not constant and also displays a circadian rhythm. © 1986 Informa UK Ltd All rights reserved: reproduction in whole or part not permitted
A corner reflector of graphene Dirac fermions as a phonon-scattering sensor
Dirac fermion optics exploits the refraction of chiral fermions across
optics-inspired Klein-tunneling barriers defined by high-transparency p-n
junctions. We consider the corner reflector (CR) geometry introduced in optics
or radars. We fabricate Dirac fermion CRs using bottom-gate-defined barriers in
hBN-encapsulated graphene. By suppressing transmission upon multiple internal
reflections, CRs are sensitive to minute phonon scattering rates. We report on
doping-independent CR transmission in quantitative agreement with a simple
scattering model including thermal phonon scattering. As a new signature of
CRs, we observe Fabry-P\'erot oscillations at low temperature, consistent with
single-path reflections. Finally, we demonstrate high-frequency operation which
promotes CRs as fast phonon detectors. Our work establishes the relevance of
Dirac fermion optics in graphene and opens a route for its implementation in
topological Dirac matter.Comment: 11 pages, 4 figure
Two-photon Lithography for 3D Magnetic Nanostructure Fabrication
Ferromagnetic materials have been utilised as recording media within data
storage devices for many decades. Confinement of the material to a two
dimensional plane is a significant bottleneck in achieving ultra-high recording
densities and this has led to the proposition of three dimensional (3D)
racetrack memories that utilise domain wall propagation along nanowires.
However, the fabrication of 3D magnetic nanostructures of complex geometry is
highly challenging and not easily achievable with standard lithography
techniques. Here, by using a combination of two-photon lithography and
electrochemical deposition, we show a new approach to construct 3D magnetic
nanostructures of complex geometry. The magnetic properties are found to be
intimately related to the 3D geometry of the structure and magnetic imaging
experiments provide evidence of domain wall pinning at a 3D nanostructured
junction
Isomorph invariance of the structure and dynamics of classical crystals
This paper shows by computer simulations that some crystalline systems have
curves in their thermodynamic phase diagrams, so-called isomorphs, along which
structure and dynamics in reduced units are invariant to a good approximation.
The crystals are studied in a classical-mechanical framework, which is
generally a good description except significantly below melting. The existence
of isomorphs for crystals is validated by simulations of particles interacting
via the Lennard-Jones pair potential arranged into a face-centered cubic (FCC)
crystalline structure; the slow vacancy-jump dynamics of a defective FCC
crystal is also shown to be isomorph invariant. In contrast, a NaCl crystal
model does not exhibit isomorph invariances. Other systems simulated, though in
less detail, are the Wahnstrom binary Lennard-Jones crystal with the Laves crystal structure, monatomic FCC crystals of particles
interacting via the Buckingham pair potential and via a novel purely repulsive
pair potential diverging at a finite separation, an ortho-terphenyl molecular
model, and SPC/E hexagonal ice. Except for NaCl and ice, the crystals simulated
all have isomorphs. Based on these findings and previous simulations of liquid
models, we conjecture that crystalline solids with isomorphs include most or
all formed by atoms or molecules interacting via metallic or van der Waals
forces, whereas covalently- or hydrogen-bonded crystals are not expected to
have isomorphs. Crystals of ions or dipolar molecules constitute a limiting
case for which isomorphs are only expected when the Coulomb interactions are
relatively weak. We briefly discuss the consequences of the findings for
theories of melting and crystallization
Shortened Tracer Uptake Time in GA-68-DOTATOC-PET of Meningiomas Does Not Impair Diagnostic Accuracy and PET Volume Definition
Ga-68-DOTATOC-PET/MRI can affect the planning target volume (PTV) definition of meningiomas before radiosurgery. A shorter tracer uptake time before image acquisition could allow the examination of more patients. The aim of this study was to investigate if shortening uptake time is possible without compromising diagnostic accuracy and PET volume. Fifteen patients (f = 12; mean age 52 years (34-80 years)) with meningiomas were prospectively examined with dynamic [68Ga]Ga-68-labeled [DOTA0-Phe1-Tyr3] octreotide (Ga-68-DOTATOC)-PET/MRI over 70 min before radiosurgery planning. Meningiomas were delineated manually in the PET dataset. PET volumes at each time point were compared to the reference standard 60 min post tracer injection (p.i.) using the Friedman test followed by a Wilcoxon signed-rank test and Bonferroni correction. In all patients, the earliest time point with 100% lesion detection compared to 60 min p.i. was identified. PET volumes did not change significantly from 15 min p.i. (p = 1.0) compared to 60 min p.i. The earliest time point with 100% lesion detection in all patients was 10 min p.i. In patients with meningiomas undergoing Ga-68-DOTATOC-PET, the tracer uptake time can safely be reduced to 15 min p.i. with comparable PET volume and 100% lesion detection compared to 60 min p.i
Scientific Objectives of Einstein Telescope
The advanced interferometer network will herald a new era in observational
astronomy. There is a very strong science case to go beyond the advanced
detector network and build detectors that operate in a frequency range from 1
Hz-10 kHz, with sensitivity a factor ten better in amplitude. Such detectors
will be able to probe a range of topics in nuclear physics, astronomy,
cosmology and fundamental physics, providing insights into many unsolved
problems in these areas.Comment: 18 pages, 4 figures, Plenary talk given at Amaldi Meeting, July 201
Swift follow-up observations of candidate gravitational-wave transient events
We present the first multi-wavelength follow-up observations of two candidate
gravitational-wave (GW) transient events recorded by LIGO and Virgo in their
2009-2010 science run. The events were selected with low latency by the network
of GW detectors and their candidate sky locations were observed by the Swift
observatory. Image transient detection was used to analyze the collected
electromagnetic data, which were found to be consistent with background.
Off-line analysis of the GW data alone has also established that the selected
GW events show no evidence of an astrophysical origin; one of them is
consistent with background and the other one was a test, part of a "blind
injection challenge". With this work we demonstrate the feasibility of rapid
follow-ups of GW transients and establish the sensitivity improvement joint
electromagnetic and GW observations could bring. This is a first step toward an
electromagnetic follow-up program in the regime of routine detections with the
advanced GW instruments expected within this decade. In that regime
multi-wavelength observations will play a significant role in completing the
astrophysical identification of GW sources. We present the methods and results
from this first combined analysis and discuss its implications in terms of
sensitivity for the present and future instruments.Comment: Submitted for publication 2012 May 25, accepted 2012 October 25,
published 2012 November 21, in ApJS, 203, 28 (
http://stacks.iop.org/0067-0049/203/28 ); 14 pages, 3 figures, 6 tables;
LIGO-P1100038; Science summary at
http://www.ligo.org/science/Publication-S6LVSwift/index.php ; Public access
area to figures, tables at
https://dcc.ligo.org/cgi-bin/DocDB/ShowDocument?docid=p110003
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