6,550 research outputs found
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The rats in Hawaiian sugarcane
Heavy losses In Hawaiian sugarcane are caused by Polynesian rats (Rattus exulans), Norway rats (R. norvegicus), and black rats (R. rattus). Relative population levels, movement patterns, damage to sugarcane, and suggested timing of control during five stages of the 2-year crop cycle are described. The progress toward the registering of zinc phosphide for use in crops and the development of other rodenticides are mentioned
MHD Mode Conversion around a 2D Magnetic Null Point
Mode conversion occurs when a wave passes through a region where the sound
and Alfven speeds are equal. At this point there is a resonance, which allows
some of the incident wave to be converted into a different mode. We study this
phenomenon in the vicinity of a two-dimensional, coronal null point. As a wave
approaches the null it passes from low- to high-beta plasma, allowing
conversion to take place. We simulate this numerically by sending in a slow
magnetoacoustic wave from the upper boundary; as this passes through the
conversion layer a fast wave can clearly be seen propagating ahead. Numerical
simulations combined with an analytical WKB investigation allow us to determine
and track both the incident and converted waves throughout the domain.Comment: 4 pages, 2 figure
Developing a computer aided design tool for inclusive design
The purpose of this study was to investigate age-related changes in the performance of a range of movement tasks for integration into a computer aided design (CAD) tool for use in inclusive design
The South Dakota cooperative land use effort: A state level remote sensing demonstration project
Remote sensing technology can satisfy or make significant contributions toward satisfying many of the information needs of governmental natural resource planners and policy makers. Recognizing this potential, the South Dakota State Planning Bureau and the EROS Data Center together formulated the framework for an ongoing Land Use and Natural Resource Inventory and Information System Program. Statewide land use/land cover information is generated from LANDSAT digital data and high altitude photography. Many applications of the system are anticipated as it evolves and data are added from more conventional sources. The conceptualization, design, and implementation of the program are discussed
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Differential alphav integrin-mediated Ras-ERK signaling during two pathways of angiogenesis.
Antagonists of alphavbeta3 and alphavbeta5 disrupt angiogenesis in response to bFGF and VEGF, respectively. Here, we show that these alphav integrins differentially contribute to sustained Ras-extracellular signal-related kinase (Ras-ERK) signaling in blood vessels, a requirement for endothelial cell survival and angiogenesis. Inhibition of FAK or alphavbeta5 disrupted VEGF-mediated Ras and c-Raf activity on the chick chorioallantoic membrane, whereas blockade of FAK or integrin alphavbeta3 had no effect on bFGF-mediated Ras activity, but did suppress c-Raf activation. Furthermore, retroviral delivery of active Ras or c-Raf promoted ERK activity and angiogenesis, which anti-alphavbeta5 blocked upstream of Ras, whereas anti-alphavbeta3 blocked downstream of Ras, but upstream of c-Raf. The activation of c-Raf by bFGF/alphavbeta3 not only depended on FAK, but also required p21-activated kinase-dependent phosphorylation of serine 338 on c-Raf, whereas VEGF-mediated c-Raf phosphorylation/activation depended on Src, but not Pak. Thus, integrins alphavbeta3 and alphavbeta5 differentially regulate the Ras-ERK pathway, accounting for distinct vascular responses during two pathways of angiogenesis
Simple scale interpolator facilitates reading of graphs
Set of cards with scale divisions and a scale finder permits accurate reading of the coordinates of points on linear or logarithmic graphs plotted on rectangular grids. The set contains 34 different scales for linear plotting and 28 single cycle scales for log plots
Consequences of spontaneous reconnection at a two-dimensional non-force-free current layer
Magnetic neutral points, where the magnitude of the magnetic field vanishes
locally, are potential locations for energy conversion in the solar corona. The
fact that the magnetic field is identically zero at these points suggests that
for the study of current sheet formation and of any subsequent resistive
dissipation phase, a finite beta plasma should be considered, rather than
neglecting the plasma pressure as has often been the case in the past. The
rapid dissipation of a finite current layer in non-force-free equilibrium is
investigated numerically, after the sudden onset of an anomalous resistivity.
The aim of this study is to determine how the energy is redistributed during
the initial diffusion phase, and what is the nature of the outward transmission
of information and energy. The resistivity rapidly diffuses the current at the
null point. The presence of a plasma pressure allows the vast majority of the
free energy to be transferred into internal energy. Most of the converted
energy is used in direct heating of the surrounding plasma, and only about 3%
is converted into kinetic energy, causing a perturbation in the magnetic field
and the plasma which propagates away from the null at the local fast
magnetoacoustic speed. The propagating pulses show a complex structure due to
the highly non-uniform initial state. It is shown that this perturbation
carries no net current as it propagates away from the null. The fact that,
under the assumptions taken in this paper, most of the magnetic energy released
in the reconnection converts internal energy of the plasma, may be highly
important for the chromospheric and coronal heating problem
Superradiance for atoms trapped along a photonic crystal waveguide
We report observations of superradiance for atoms trapped in the near field
of a photonic crystal waveguide (PCW). By fabricating the PCW with a band edge
near the D transition of atomic cesium, strong interaction is achieved
between trapped atoms and guided-mode photons. Following short-pulse
excitation, we record the decay of guided-mode emission and find a superradiant
emission rate scaling as for average atom number atoms, where
is the peak single-atom radiative decay
rate into the PCW guided mode and is the Einstein- coefficient
for free space. These advances provide new tools for investigations of
photon-mediated atom-atom interactions in the many-body regime.Comment: 11 pages, 10 figure
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