11,451 research outputs found
Gravity anomaly detection: Apollo/Soyuz
The Goddard Apollo-Soyuz Geodynamics Experiment is described. It was performed to demonstrate the feasibility of tracking and recovering high frequency components of the earth's gravity field by utilizing a synchronous orbiting tracking station such as ATS-6. Gravity anomalies of 5 MGLS or larger having wavelengths of 300 to 1000 kilometers on the earth's surface are important for geologic studies of the upper layers of the earth's crust. Short wavelength Earth's gravity anomalies were detected from space. Two prime areas of data collection were selected for the experiment: (1) the center of the African continent and (2) the Indian Ocean Depression centered at 5% north latitude and 75% east longitude. Preliminary results show that the detectability objective of the experiment was met in both areas as well as at several additional anomalous areas around the globe. Gravity anomalies of the Karakoram and Himalayan mountain ranges, ocean trenches, as well as the Diamantina Depth, can be seen. Maps outlining the anomalies discovered are shown
Support for graphicacy: a review of textbooks available to accounting students
This Teaching Note reports on the support available in textbooks for graphicacy that will help students understand the complexities of graphical displays. Graphical displays play a significant role in financial reporting, and studies have found evidence of measurement distortion and selection bias. To understand the complexities of graphical displays, students need a sound understanding of graphicacy and support from the textbooks available to them to develop that understanding. The Teaching Note reports on a survey that examined the textbooks available to students attending two Scottish universities. The support of critical graphicacy skills was examined in conjunction with textbook characteristics. The survey, which was not restricted to textbooks designated as required reading, examined the textbooks for content on data measurement and graphical displays. The findings highlight a lack of support for graphicacy in the textbooks selected. The study concludes that accounting educators need to scrutinize more closely the selection of textbooks and calls for more extensive research into textbooks as a pedagogic tool
Removal of luminal content protects the small intestine during hemorrhagic shock but is not sufficient to prevent lung injury.
The small intestine plays a key role in the pathogenesis of multiple organ failure following circulatory shock. Current results show that reduced perfusion of the small intestine compromises the mucosal epithelial barrier, and the intestinal contents (including pancreatic digestive enzymes and partially digested food) can enter the intestinal wall and transport through the circulation or mesenteric lymph to other organs such as the lung. The extent to which the luminal contents of the small intestine mediate tissue damage in the intestine and lung is poorly understood in shock. Therefore, rats were assigned to three groups: No-hemorrhagic shock (HS) control and HS with or without a flushed intestine. HS was induced by reducing the mean arterial pressure (30 mmHg; 90 min) followed by return of shed blood and observation (3 h). The small intestine and lung were analyzed for hemorrhage, neutrophil accumulation, and cellular membrane protein degradation. After HS, animals with luminal contents had increased neutrophil accumulation, bleeding, and destruction of E-cadherin in the intestine. Serine protease activity was elevated in mesenteric lymph fluid collected from a separate group of animals subjected to intestinal ischemia/reperfusion. Serine protease activity was elevated in the plasma after HS but was detected in lungs only in animals with nonflushed lumens. Despite removal of the luminal contents, lung injury occurred in both groups as determined by elevated neutrophil accumulation, permeability, and lung protein destruction. In conclusion, luminal contents significantly increase intestinal damage during experimental HS, suggesting transport of luminal contents across the intestinal wall should be minimized
Non-linear optomechanical measurement of mechanical motion
Precision measurement of non-linear observables is an important goal in all
facets of quantum optics. This allows measurement-based non-classical state
preparation, which has been applied to great success in various physical
systems, and provides a route for quantum information processing with otherwise
linear interactions. In cavity optomechanics much progress has been made using
linear interactions and measurement, but observation of non-linear mechanical
degrees-of-freedom remains outstanding. Here we report the observation of
displacement-squared thermal motion of a micro-mechanical resonator by
exploiting the intrinsic non-linearity of the radiation pressure interaction.
Using this measurement we generate bimodal mechanical states of motion with
separations and feature sizes well below 100~pm. Future improvements to this
approach will allow the preparation of quantum superposition states, which can
be used to experimentally explore collapse models of the wavefunction and the
potential for mechanical-resonator-based quantum information and metrology
applications.Comment: 8 pages, 4 figures, extensive supplementary material available with
published versio
sd-shell study with a multi-configuration mixing approach designed for large scale nuclear structure calculations
A systematic numerical investigation of a recently developed nuclear structure approach is presented which diagonalizes the Hamiltonian in the space of the symmetry-projected Hartree-Fock-Bogoliubov (HFB) vacuum and symmetry-projected quasiparticle excitations with respect to it. The underlying HFB transformation, which is assumed to be time-reversal and axially symmetric, is determined by variation after the projection. The model allows the use of large basis systems. It has been applied to the calculation of energy spectra of several even-even, odd-odd and odd mass nuclei in the sd shell with mass numbers reaching from A=20 to 30. The Chung-Wildenthal interaction has been used. Good agreement with the exact shell model diagonalization and a considerable improvement on a previous approach, where the HFB transformation was significantly more restricted, is obtained
Predicting narrow states in the spectrum of a nucleus beyond the proton drip line
Properties of particle-unstable nuclei lying beyond the proton drip line can
be ascertained by considering those (usually known) properties of its mirror
neutron-rich system. We have used a multi-channel algebraic scattering theory
to map the known properties of the neutron-C system to those of the
proton-O one from which we deduce that the particle-unstable
F will have a spectrum of two low lying broad resonances of positive
parity and, at higher excitation, three narrow negative parity ones. A key
feature is to use coupling to Pauli-hindered states in the target.Comment: 5 pages, 3 figure
Continuum coupled cluster expansion
We review the basics of the coupled-cluster expansion formalism for numerical
solutions of the many-body problem, and we outline the principles of an
approach directed towards an adequate inclusion of continuum effects in the
associated single-energy spectrum. We illustrate our findings by considering
the simple case of a single-particle quantum mechanics problem.Comment: 16 pages, 1 figur
Three-body breakup within the fully discretized Faddeev equations
A novel approach is developed to find the three-body breakup amplitudes and
cross sections within the modified Faddeev equation framework. The method is
based on the lattice-like discretization of the three-body continuum with a
three-body stationary wave-packet basis in momentum space. The approach makes
it possible to simplify drastically all the three- and few-body breakup
calculations due to discrete wave-packet representations for the few-body
continuum and simultaneous lattice representation for all the scattering
operators entering the integral equation kernels. As a result, the few-body
breakup can be treated as a particular case of multi-channel scattering in
which part of the channels represents the true few-body continuum states. As an
illustration for the novel approach, an accurate calculations for the
three-body breakup process with non-local and local
interactions are calculated. The results obtained reproduce nicely the
benchmark calculation results using the traditional Faddeev scheme which
requires much more tedious and time-consuming calculations.Comment: 17 pages, 13 figure
Infinitesimal Variations of Hodge Structure at Infinity
By analyzing the local and infinitesimal behavior of degenerating polarized
variations of Hodge structure the notion of infinitesimal variation of Hodge
structure at infinity is introduced. It is shown that all such structures can
be integrated to polarized variations of Hodge structure and that, conversely,
all are limits of infinitesimal variations of Hodge structure (IVHS) at finite
points. As an illustration of the rich information encoded in this new
structure, some instances of the maximal dimension problem for this type of
infinitesimal variation are presented and contrasted with the "classical" case
of IVHS at finite points
Comparison of spectral entropy and bispectral index electroencephalography in coronary artery bypass graft surgery
OBJECTIVE: The study's aim was to compare response entropy (RE) and state entropy (SE) with bispectral index (BIS) electroencephalography (EEG) as an alternative cerebral monitoring tool in patients scheduled for coronary artery bypass graft surgery. DESIGN: Prospective, observational single-center study. SETTING: University hospital. PARTICIPANTS: Thirty patients undergoing coronary artery bypass graft surgery receiving remifentanil-propofol anesthesia. INTERVENTIONS: Surgery was performed with cardiopulmonary bypass (CPB) and cardiac arrest in 15 patients, with CPB without cardiac arrest in 9 patients and without CPB in 6 patients. MEASUREMENTS AND MAIN RESULTS: RE, SE, BIS, burst suppression ratio (BSR), and frontal electromyography (f-EMG) were detected simultaneously. RE and SE compared favorably with BIS and their correlations were strong (r(2) = 0.6, r(2) = 0.55, respectively). The mean bias of RE and BIS was -1.8, but limits of agreement were high (+20.5/-24.1). RE and SE tended to be lower than the BIS values in the CPB subgroups. The detection of BSR was similar with RE and SE and the BIS. A strong correlation existed between BIS and f-EMG (r(2) = 0.62) in contrast to RE (r(2) = 0.45) and SE (r(2) =0.39). BIS monitoring was significantly more disturbed than RE and SE with 9.1% +/-10.9% and 0.1% +/- 0.2% of the total anesthesia time, respectively. Neither implicit nor explicit memory was shown. CONCLUSION: RE and SE are comparable with the BIS but showed significantly less interference from f-EMG and superior resistance against artifacts. Thus, spectral entropy is more suitable than the BIS during propofol-remifentanil anesthesia in cardiac surgery patients
- …