8,205 research outputs found
K+ -> pi+ nu nu(bar) and FCNC from non-universal Z' bosons
Motivated by the E787 and E949 result for K+ -> pi+ nu nu(bar) we examine the
effects of a new non-universal right-handed Z' boson on flavor changing
processes. We place bounds on the tree-level FCNC from K-K(bar) and B-B(bar)
mixing as well as from the observed CP violation in kaon decay. We discuss the
implications for K -> pi nu nu(bar), B -> X nu nu(bar) and B -> tau+ tau-. We
find that existing bounds allow substantial enhancements in the K+ -> pi+ nu
nu(bar) rate, particularly through a new one-loop Z' penguin operator.Comment: Typos corrected, references added, version to appear in PR
K_L \ra \mu^\pm e^\mp \nu \overline{\nu} as background to K_L \ra \mu^\pm e^\mp
We consider the process K_L \ra \mu^\pm e^\mp \nu \overline{\nu} at next to
leading order in chiral perturbation theory. This process occurs in the
standard model at second order in the weak interaction and constitutes a
potential background in searches for new physics through the modes K_L \ra
\mu^\pm e^\mp. We find that the same cut, ~MeV, used to remove
the sequential decays K_{l3}\ra \pi_{l2} pushes the B(K_L \ra \mu^\pm e^\mp
\nu \overline{\nu}) to the level, effectively removing it as a
background.Comment: 8 pages, LaTeX, 1 figure appended as postscript file after
\end{document}. Fermilab-Pub-93/024-
Mn valence instability in La2/3Ca1/3MnO3 thin films
A Mn valence instability on La2/3Ca1/3MnO3 thin films, grown on LaAlO3
(001)substrates is observed by x-ray absorption spectroscopy at the Mn L-edge
and O K-edge. As-grown samples, in situ annealed at 800 C in oxygen, exhibit a
Curie temperature well below that of the bulk material. Upon air exposure a
reduction of the saturation magnetization, MS, of the films is detected.
Simultaneously a Mn2+ spectral signature develops, in addition to the expected
Mn3+ and Mn4+ contributions, which increases with time. The similarity of the
spectral results obtained by total electron yield and fluorescence yield
spectroscopy indicates that the location of the Mn valence anomalies is not
confined to a narrow surface region of the film, but can extend throughout the
whole thickness of the sample. High temperature annealing at 1000 C in air,
immediately after growth, improves the magnetic and transport properties of
such films towards the bulk values and the Mn2+ signature in the spectra does
not appear. The Mn valence is then stable even to prolonged air exposure. We
propose a mechanism for the Mn2+ ions formation and discuss the importance of
these observations with respect to previous findings and production of thin
films devices.Comment: Double space, 21 pages, 6 figure
Frontiers of the physics of dense plasmas and planetary interiors: experiments, theory, applications
Recent developments of dynamic x-ray characterization experiments of dense
matter are reviewed, with particular emphasis on conditions relevant to
interiors of terrestrial and gas giant planets. These studies include
characterization of compressed states of matter in light elements by x-ray
scattering and imaging of shocked iron by radiography. Several applications of
this work are examined. These include the structure of massive "Super Earth"
terrestrial planets around other stars, the 40 known extrasolar gas giants with
measured masses and radii, and Jupiter itself, which serves as the benchmark
for giant planets.Comment: Accepted to Physics of Plasmas special issue. Review from
HEDP/HEDLA-08, April 12-15, 200
Cloud Optical Depth Retrievals from Solar Background "signal" of Micropulse Lidars
Pulsed lidars are commonly used to retrieve vertical distributions of cloud and aerosol layers. It is widely believed that lidar cloud retrievals (other than cloud base altitude) are limited to optically thin clouds. Here we demonstrate that lidars can retrieve optical depths of thick clouds using solar background light as a signal, rather than (as now) merely a noise to be subtracted. Validations against other instruments show that retrieved cloud optical depths agree within 10-15% for overcast stratus and broken clouds. In fact, for broken cloud situations one can retrieve not only the aerosol properties in clear-sky periods using lidar signals, but also the optical depth of thick clouds in cloudy periods using solar background signals. This indicates that, in general, it may be possible to retrieve both aerosol and cloud properties using a single lidar. Thus, lidar observations have great untapped potential to study interactions between clouds and aerosols
Successful Demonstration of Relieving CO2-Solid-Forming Streams through a Pressure Relief System
PresentationThe demand for natural gas, considered the cleanest burning hydrocarbon fuel available, is expected to rise significantly over the foreseeable future. However, natural gas produced from many major reservoirs can contain significant amounts of carbon dioxide (CO2) and must be treated before it can be used as an environmentally acceptable fuel. These treatment processes often require high-pressure operations forming highly concentrated CO2-rich streams. Pressure protection for these systems has been challenging to date because of the potential for solids generation upon pressure let down and the consequent potential for plugging that the solids present. ExxonMobil has completed successful field demonstrations relieving dehydrated, CO2-rich liquid and vapor streams forming up to 40 wt% solids in relief lines. The results of these field demonstration tests as well as learnings from design of CO2-solid-forming relief systems are discussed in this paper
Cytotoxic activity of fungal metabolites from the Pathogenic Fungus Beauveria bassiana: an intraspecific evaluation of beauvericin production.
Digestive alfa-amylases from Tecia solanivora larvae (Lepidoptera: Gelechiidae): response to pH, temperature and plant amylase inhibitors.
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Biological activity of poriferans extracts from the Colombian Caribbean on Meloidogyne incognita and Spodoptera frugiperda IPLB-SF-21 cell line.
Sinconbiol
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