24,913 research outputs found
Multiple H-Rearrangements in 10-Benzylthio-dithranol Radical Cations
10-Alkylthio- and 10-arylthio-derivatives of dithranol (anthralin;
1,8-dihydroxy-9-anthrone) are of interest in search for new anti-psoriatic
agents2 , 3 ). By working out ms procedures for unequivocal identification of
trace amounts of these compounds4 ) it was established that in case of
10-phenylthio-dithranol putative by-products, especially one giving rise to
ions at m/z = 226 (dithranol), are artefacts of thermal reaction in the mass
spectrometer1). In the EI-MS of those 10-substituted dithranols containing
a S-CH2R chain, however, these ions (m/z = 226) arise from M + * as well.
Scope and mechanism of their formation was examined by analyzing
compound 1 and its D-labelled derivatives 2 and 3
Identification of the dominant diffusing species in silicide formation
Implanted noble gas atoms of Xe have been used as diffusion markers in the growth study of three silicides: Ni2Si, VSi2, and TiSi2. Backscattering of MeV He has been used to determine the displacement of the markers. We found that while Si atoms predominate the diffusion in VSi2 and TiSi2, Ni atoms are the faster moving species in Ni2Si
Absolute differential cross sections for electron-impact excitation of CO near threshold: II. The Rydberg states of CO
Absolute differential cross sections for electron-impact excitation of Rydberg states of CO have been measured from threshold to 3.7 eV above threshold and for scattering angles between 20° and 140°. Measured excitation functions for the b 3Σ+, B 1Σ+ and E 1π states are compared with cross sections calculated by the Schwinger multichannel method. The behaviour of the excitation functions for these states and for the j 3Σ+ and C 1Σ+ states is analysed in terms of negative-ion states. One of these resonances has not been previously reported
Deep learning with convolutional neural networks for decoding and visualization of EEG pathology
We apply convolutional neural networks (ConvNets) to the task of
distinguishing pathological from normal EEG recordings in the Temple University
Hospital EEG Abnormal Corpus. We use two basic, shallow and deep ConvNet
architectures recently shown to decode task-related information from EEG at
least as well as established algorithms designed for this purpose. In decoding
EEG pathology, both ConvNets reached substantially better accuracies (about 6%
better, ~85% vs. ~79%) than the only published result for this dataset, and
were still better when using only 1 minute of each recording for training and
only six seconds of each recording for testing. We used automated methods to
optimize architectural hyperparameters and found intriguingly different ConvNet
architectures, e.g., with max pooling as the only nonlinearity. Visualizations
of the ConvNet decoding behavior showed that they used spectral power changes
in the delta (0-4 Hz) and theta (4-8 Hz) frequency range, possibly alongside
other features, consistent with expectations derived from spectral analysis of
the EEG data and from the textual medical reports. Analysis of the textual
medical reports also highlighted the potential for accuracy increases by
integrating contextual information, such as the age of subjects. In summary,
the ConvNets and visualization techniques used in this study constitute a next
step towards clinically useful automated EEG diagnosis and establish a new
baseline for future work on this topic.Comment: Published at IEEE SPMB 2017 https://www.ieeespmb.org/2017
Gamma–ray spectroscopy with single–carrier collection in high–resistivity semiconductors
With the standard plane–parallel configuration of semiconductor detectors, good γ–ray spectra can only be obtained when both electrons and holes are completely collected. We show by calculations (and experiments) that with contacts of hemispherical configuration one can obtain γ–ray spectra of adequate resolution and with signal heights of nearly full amplitude even when only one type of carrier is collected. Experiments with CdTe detectors for which the µτ product for electrons is about 10^(3) times that of the holes confirm these calculations. The adoption of hemispherical contacts thus widens the range of high–resistivity semiconductors potentially acceptable for γ–ray detection at room temperature
The PlaNet Consortium: A Network of European Plant Databases Connecting Plant Genome Data in an Integrated Biological Knowledge Resource
The completion of the Arabidopsis genome and the large collections of other plant
sequences generated in recent years have sparked extensive functional genomics
efforts. However, the utilization of this data is inefficient, as data sources are
distributed and heterogeneous and efforts at data integration are lagging behind.
PlaNet aims to overcome the limitations of individual efforts as well as the
limitations of heterogeneous, independent data collections. PlaNet is a distributed
effort among European bioinformatics groups and plant molecular biologists to
establish a comprehensive integrated database in a collaborative network. Objectives
are the implementation of infrastructure and data sources to capture plant genomic
information into a comprehensive, integrated platform. This will facilitate the
systematic exploration of Arabidopsis and other plants. New methods for data
exchange, database integration and access are being developed to create a highly
integrated, federated data resource for research. The connection between the
individual resources is realized with BioMOBY. BioMOBY provides an architecture
for the discovery and distribution of biological data through web services. While
knowledge is centralized, data is maintained at its primary source without a need for
warehousing. To standardize nomenclature and data representation, ontologies and
generic data models are defined in interaction with the relevant communities.Minimal
data models should make it simple to allow broad integration, while inheritance allows
detail and depth to be added to more complex data objects without losing integration.
To allow expert annotation and keep databases curated, local and remote annotation
interfaces are provided. Easy and direct access to all data is key to the project
Variational Calculation for the Equation of State of Nuclear Matter at Finite Temperatures
An equation of state (EOS) for uniform nuclear matter is constructed at zero
and finite temperatures with the variational method starting from the realistic
nuclear Hamiltonian composed of the Argonne V18 and UIX potentials. The energy
is evaluated in the two-body cluster approximation with the three-body-force
contribution treated phenomenologically so as to reproduce the empirical
saturation conditions. The obtained energies for symmetric nuclear matter and
neutron matter at zero temperature are in fair agreement with those by Akmal,
Pandharipande and Ravenhall, and the maximum mass of the neutron star is 2.2
Msolar. At finite temperatures, a variational method by Schmidt and
Pandharipande is employed to evaluate the free energy, which is used to derive
various thermodynamic quantities of nuclear matter necessary for supernova
simulations. The result of this variational method at finite temperatures is
found to be self-consistent.Comment: Revised Versio
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