17,866 research outputs found
Studies in the biosynthesis of erythrina alkaloids
Imperial Users onl
Ocean properties
The author has identified the following significant results. Results of testing the CP program indicate that the best results can be obtained in the near infrared water bands. The absorption due to water vapor and carbon dioxide in the thermal infrared band appeared to be less reliable in comparison to spacecraft-acquired data and band models. Comparisons of laboratory carbon dioxide transmission in the thermal infrared band show good agreement except in regions where lines are known to be missing. The comparison of ozone transmission at a wavelength of 9.6 micrometers to laboratory data showed unexceptedly large differences
Acoustic prediction methods for rocket engines, including the effects of clustered engines and deflected exhaust flow
Acoustic prediction methods for rocket engine
Method of statistical filtering
Minimal formula for bounding the cross correlation between a random forcing function and the state error when this correlation is unknown is used in optimal linear filter theory applications. Use of the bound results in overestimation of the estimation-error covariance
Localization-protected order in spin chains with non-Abelian discrete symmetries
We study the non-equilibrium phase structure of the three-state random
quantum Potts model in one dimension. This spin chain is characterized by a
non-Abelian symmetry recently argued to be incompatible with the
existence of a symmetry-preserving many-body localized (MBL) phase. Using exact
diagonalization and a finite-size scaling analysis, we find that the model
supports two distinct broken-symmetry MBL phases at strong disorder that either
break the clock symmetry or a chiral
symmetry. In a dual formulation, our results indicate the existence of a stable
finite-temperature topological phase with MBL-protected parafermionic end zero
modes. While we find a thermal symmetry-preserving regime for weak disorder,
scaling analysis at strong disorder points to an infinite-randomness critical
point between two distinct broken-symmetry MBL phases.Comment: 5 pages, 3 figures main text; 6 pages, 3 figures supplemental
material; Version 2 includes a corrected the form of the chiral order
parameter, and corresponding data, as well as larger system size numerics,
with no change to the phase structur
Particle-hole symmetry, many-body localization, and topological edge modes
We study the excited states of interacting fermions in one dimension with
particle-hole symmetric disorder (equivalently, random-bond XXZ chains) using a
combination of renormalization group methods and exact diagonalization. Absent
interactions, the entire many-body spectrum exhibits infinite-randomness
quantum critical behavior with highly degenerate excited states. We show that
though interactions are an irrelevant perturbation in the ground state, they
drastically affect the structure of excited states: even arbitrarily weak
interactions split the degeneracies in favor of thermalization (weak disorder)
or spontaneously broken particle-hole symmetry, driving the system into a
many-body localized spin glass phase (strong disorder). In both cases, the
quantum critical properties of the non-interacting model are destroyed, either
by thermal decoherence or spontaneous symmetry breaking. This system then has
the interesting and counterintuitive property that edges of the many-body
spectrum are less localized than the center of the spectrum. We argue that our
results rule out the existence of certain excited state symmetry-protected
topological orders.Comment: 9 pages. 7 figure
Biological characteristics and mortality of western butterfish (Pentapodus vitta), an abundant bycatch species of prawn trawling and recreational fishing in a large subtropical embayment
The western butterfish (Pentapodus vitta) is numerous in the bycatch of prawn trawling and recreational fishing in Shark Bay, Western Australia. We have thus determined crucial aspects of its biological characteristics and the potential impact of fishing on its abundance within this large subtropical marine embayment. Although both sexes attained a maximum age of 8 years, males grow more rapidly and to a larger size. Maturity is attained at the end of the first year of life and spawning occurs between October and January. The use of a Bayesian approach to combine independent estimates for total mortality, Z, and natural mortality, M, yielded slightly higher point estimates for Z than M. This result indicates that P. vitta is lightly impacted by fishing. It is relevant that, potentially, the individuals can spawn twice before recruitment into the fishery and that 73% of recreationally caught individuals are returned live to the water
Significant techniques in the processing and interpretation of ERTS-1 data
The discipline oriented investigations underway at the Johnson Space Center (JSC) using ERTS-1 data provide an appropriate framework for the systematic evaluation of the various elements comprising a prototype multispectral data processing and analysis system. In particular such a system may be thought of as the integration of: (1) a preprocessing subsystem; (2) a spectral clustering subsystem, (3) a correlation and classification subsystem; (4) mensuration subsystem; and (5) an information management subsystem. Specific elements of this system are already operational at JSC. It is in the context of this system that technique development and application is being pursued at JSC. Aircraft, ERTS and EREP data will be utilized to refine the subsystem elements for each of the data acquisition systems or system combinations that are optimally suited for a specific Earth Resources application. The techniques reported are those that have been developed to date during the utilization of ERTS-1 data in this processing and analysis system
Higgs boson hadronic branching ratios at the ILC
We present a study of the Higgs boson decay branching ratios to ,
and gluons, one of the cornerstones of the physics program at the
International Linear Collider (ILC). A standard model Higgs boson of 120\,GeV
mass, produced in the Higgs-strahlung process at \,GeV was
investigated using the full detector simulation and reconstruction procedures.
The analysis was performed in the framework of the Silicon Detector (SiD)
concept with full account of inclusive standard model backgrounds. The selected
decay modes contained two heavy flavour jets in the final state and required
excellent flavour tagging through precise reconstruction of interaction and
decay vertices in the detector. A new signal discrimination technique using
correlations of neural network outputs was used to determine the branching
ratios and estimate their uncertainties, 4.8\%, 8.4\% and 12.2\% for
, and gluons respectively.Comment: 9 Pages, 5 figures and 5 table
The role of freestream turbulence scale in subsonic flow separation
The clarification of the role of freestream turbulence scale in determining the location of boundary layer separation is discussed. Modifications to the test facility were completed. Wind tunnel flow characteristics, including turbulence parameters, were determined with two turbulence generating grids, as well as no grid. These results are summarized. Initial results on the role of scale on turbulent boundary layer separation on the upper surface of an airfoil model are also discussed
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