3,927 research outputs found
Differences in Thermal Stability of Glucosinolates in Five Brassica Vegetables
The thermal stability of individual glucosinolates within five different Brassica vegetables was studied at 100°C for different incubation times up to 120 minutes. Three vegetables that were used in this study were Brassica oleracea (red cabbage, broccoli and Brussels sprouts) and two were Brassica rapa (pak choi and Chinese cabbage). To rule out the influence of enzymatic breakdown, myrosinase was inactivated prior to the thermal treatments. The stability of three glucosinolates that occurred in all five vegetables (gluconapin, glucobrassicin and 4-methoxyglucobrassicin) varied considerably between the different vegetables. The degradation could be modeled by first order kinetics. The rate constants obtained varied between four to twenty fold between the five vegetables. Brussels sprouts showed the highest degradation rates for all three glucosinolates. The two indole glucosinolates were most stable in red cabbage, while gluconapin was most stable in broccoli. These results indicate the possibilities for plant breeding to select for cultivars in which glucosinolates are more stable during processin
MTMDAT: Automated analysis and visualization of mass spectrometry data for tertiary and quaternary structure probing of proteins
Summary: In structural biology and -genomics, nuclear magnetic resonance (NMR) spectroscopy and crystallography are the methods of choice, but sample requirements can be hard to fulfil. Valuable structural information can also be obtained by using a combination of limited proteolysis and mass spectrometry, providing not only knowledge of how to improve sample conditions for crystallization trials or NMR spectrosopy by gaining insight into subdomain identities but also probing tertiary and quaternary structure, folding and stability, ligand binding, protein interactions and the location of post-translational modifications. For high-throughput studies and larger proteins, however, this experimentally fast and easy approach produces considerable amounts of data, which until now has made the evaluation exceedingly laborious if at all manually possible. MTMDAT, equipped with a browser-like graphical user interface, accelerates this evaluation manifold by automated peak picking, assignment, data processing and visualization
Bulk and surface magnetoinductive breathers in binary metamaterials
We study theoretically the existence of bulk and surface discrete breathers
in a one-dimensional magnetic metamaterial comprised of a periodic binary array
of split-ring resonators. The two types of resonators differ in the size of
their slits and this leads to different resonant frequencies. In the framework
of the rotating-wave approximation (RWA) we construct several types of breather
excitations for both the energy-conserved and the dissipative-driven systems by
continuation of trivial breather solutions from the anticontinuous limit to
finite couplings. Numerically-exact computations that integrate the full model
equations confirm the quality of the RWA results. Moreover, it is demonstrated
that discrete breathers can spontaneously appear in the dissipative-driven
system as a results of a fundamental instability.Comment: 10 pages, 16 figure
Clock and Trigger Synchronization between Several Chassis of Digital Data Acquisition Modules
In applications with segmented high purity Ge detectors or other detector
arrays with tens or hundreds of channels, where the high development cost and
limited flexibility of application specific integrated circuits outweigh their
benefits of low power and small size, the readout electronics typically consist
of multi-channel data acquisition modules in a common chassis for power, clock
and trigger distribution, and data readout. As arrays become larger and reach
several hundred channels, the readout electronics have to be divided over
several chassis, but still must maintain precise synchronization of clocks and
trigger signals across all channels. This division becomes necessary not only
because of limits given by the instrumentation standards on module size and
chassis slot numbers, but also because data readout times increase when more
modules share the same data bus and because power requirements approach the
limits of readily available power supplies. In this paper, we present a method
for distributing clocks and triggers between 4 PXI chassis containing DGF
Pixie-16 modules with up to 226 acquisition channels per chassis in a data
acquisition system intended to instrument the over 600 channels of the SeGA
detector array at the National Superconducting Cyclotron Laboratory. Our
solution is designed to achieve synchronous acquisition of detector waveforms
from all channels with a jitter of less then 1 ns, and can be extended to a
larger number of chassis if desired.Comment: CAARI 200
Tramp Ship Scheduling Problem with Berth Allocation Considerations and Time-dependent Constraints
This work presents a model for the Tramp Ship Scheduling problem including
berth allocation considerations, motivated by a real case of a shipping
company. The aim is to determine the travel schedule for each vessel
considering multiple docking and multiple time windows at the berths. This work
is innovative due to the consideration of both spatial and temporal attributes
during the scheduling process. The resulting model is formulated as a
mixed-integer linear programming problem, and a heuristic method to deal with
multiple vessel schedules is also presented. Numerical experimentation is
performed to highlight the benefits of the proposed approach and the
applicability of the heuristic. Conclusions and recommendations for further
research are provided.Comment: 16 pages, 3 figures, 5 tables, proceedings paper of Mexican
International Conference on Artificial Intelligence (MICAI) 201
Digital Availability of Product Information for Collaborative Engineering of Spacecraft
In this paper, we introduce a system to collect product information from
manufacturers and make it available in tools that are used for concurrent
design of spacecraft. The planning of a spacecraft needs experts from different
disciplines, like propulsion, power, and thermal. Since these different
disciplines rely on each other there is a high need for communication between
them, which is often realized by a Model-Based Systems Engineering (MBSE)
process and corresponding tools. We show by comparison that the product
information provided by manufacturers often does not match the information
needed by MBSE tools on a syntactic or semantic level. The information from
manufacturers is also currently not available in machine-readable formats.
Afterwards, we present a prototype of a system that makes product information
from manufacturers directly available in MBSE tools, in a machine-readable way.Comment: accepted at CDVE201
Molecular mechanism of influenza A NS1-mediated TRIM25 recognition and inhibition
RIG-I is a viral RNA sensor that induces the production of type I interferon (IFN) in response to infection with a variety of viruses. Modification of RIG-I with K63-linked poly-ubiquitin chains, synthesised by TRIM25, is crucial for activation of the RIG-I/MAVS signalling pathway. TRIM25 activity is targeted by influenza A virus non-structural protein 1 (NS1) to suppress IFN production and prevent an efficient host immune response. Here we present structures of the human TRIM25 coiled-coil-PRYSPRY module and of complexes between the TRIM25 coiled-coil domain and NS1. These structures show that binding of NS1 interferes with the correct positioning of the PRYSPRY domain of TRIM25 required for substrate ubiquitination and provide a mechanistic explanation for how NS1 suppresses RIG-I ubiquitination and hence downstream signalling. In contrast, the formation of unanchored K63-linked poly-ubiquitin chains is unchanged by NS1 binding, indicating that RING dimerisation of TRIM25 is not affected by NS1
Bosonic Reduction of Susy Generalized Harry Dym Equation
In this paper we construct the two component supersymmetric generalized Harry
Dym equation which is integrable and study various properties of this model in
the bosonic limit. In particular, in the bosonic limit we obtain a new
integrable system which, under a hodograph transformation, reduces to a coupled
three component system. We show how the Hamiltonian structure transforms under
a hodograph transformation and study the properties of the model under a
further reduction to a two component system. We find a third Hamiltonian
structure for this system (which has been shown earlier to be a bi-Hamiltonian
system) making this a genuinely tri-Hamiltonian system. The connection of this
system to the modified dispersive water wave equation is clarified. We also
study various properties in the dispersionless limit of our model.Comment: 21 page
Phase transformation in Si from semiconducting diamond to metallic beta-Sn phase in QMC and DFT under hydrostatic and anisotropic stress
Silicon undergoes a phase transition from the semiconducting diamond phase to
the metallic beta-Sn phase under pressure. We use quantum Monte Carlo
calculations to predict the transformation pressure and compare the results to
density functional calculations employing the LDA, PBE, PW91, WC, AM05, PBEsol
and HSE06 exchange-correlation functionals. Diffusion Monte Carlo predicts a
transition pressure of 14.0 +- 1.0 GPa slightly above the experimentally
observed transition pressure range of 11.3 to 12.6 GPa. The HSE06 hybrid
functional predicts a transition pressure of 12.4 GPa in excellent agreement
with experiments. Exchange-correlation functionals using the local-density
approximation and generalized-gradient approximations result in transition
pressures ranging from 3.5 to 10.0 GPa, well below the experimental values. The
transition pressure is sensitive to stress anisotropy. Anisotropy in the stress
along any of the cubic axes of the diamond phase of silicon lowers the
equilibrium transition pressure and may explain the discrepancy between the
various experimental values as well as the small overestimate of the quantum
Monte Carlo transition pressure
Results and recommendations from an intercomparison of six Hygroscopicity-TDMA systems
The performance of six custom-built Hygrocopicity-Tandem Differential Mobility Analyser (H-TDMA) systems was investigated in the frame of an international calibration and intercomparison workshop held in Leipzig, February 2006. The goal of the workshop was to harmonise H-TDMA measurements and develop recommendations for atmospheric measurements and their data evaluation. The H-TDMA systems were compared in terms of the sizing of dry particles, relative humidity (RH) uncertainty, and consistency in determination of number fractions of different hygroscopic particle groups. The experiments were performed in an air-conditioned laboratory using ammonium sulphate particles or an external mixture of ammonium sulphate and soot particles. The sizing of dry particles of the six H-TDMA systems was within 0.2 to 4.2% of the selected particle diameter depending on investigated size and individual system. Measurements of ammonium sulphate aerosol found deviations equivalent to 4.5% RH from the set point of 90% RH compared to results from previous experiments in the literature. Evaluation of the number fraction of particles within the clearly separated growth factor modes of a laboratory generated externally mixed aerosol was done. The data from the H-TDMAs was analysed with a single fitting routine to investigate differences caused by the different data evaluation procedures used for each H-TDMA. The differences between the H-TDMAs were reduced from +12/-13% to +8/-6% when the same analysis routine was applied. We conclude that a common data evaluation procedure to determine number fractions of externally mixed aerosols will improve the comparability of H-TDMA measurements. It is recommended to ensure proper calibration of all flow, temperature and RH sensors in the systems. It is most important to thermally insulate the aerosol humidification unit and the second DMA and to monitor these temperatures to an accuracy of 0.2 degrees C. For the correct determination of external mixtures, it is necessary to take into account size-dependent losses due to diffusion in the plumbing between the DMAs and in the aerosol humidification unit.Peer reviewe
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