13,468 research outputs found
The non-uniform, dynamic atmosphere of Betelgeuse observed at mid-infrared wavelengths
We present an interferometric study of the continuum surface of the red
supergiant star Betelgeuse at 11.15 microns wavelength, using data obtained
with the Berkeley Infrared Spatial Interferometer each year between 2006 and
2010. These data allow an investigation of an optically thick layer within 1.4
stellar radii of the photosphere. The layer has an optical depth of ~1 at 11.15
microns, and varies in temperature between 1900 K and 2800 K and in outer
radius between 1.16 and 1.36 stellar radii. Electron-hydrogen atom collisions
contribute significantly to the opacity of the layer. The layer has a
non-uniform intensity distribution that changes between observing epochs. These
results indicate that large-scale surface convective activity strongly
influences the dynamics of the inner atmosphere of Betelgeuse, and mass-loss
processes.Comment: 13 pages, 5 figures, in press (ApJ
Quantitative Determination of Enhanced and Suppressed Transmission through Subwavelength Slit Arrays in Silver Films
Measurement of the transmitted intensity from a coherent monomode light
source through a series of subwavelength slit arrays in Ag films, with varying
array pitch and number of slits, demonstrate enhancement (suppression) by as
much as a factor of 6 (9) when normalized to that of an isolated slit.
Pronounced minima in the transmitted intensity were observed at array pitches
corresponding to lambda_SPP, 2lambda_SPP, and 3lambda_SPP where lambda_SPP is
the wavelength of the surface plasmon polariton (SPP). Increasing the number of
slits to more than four does not increase appreciably the per-slit transmission
intensity. These results are consistent with a model for interference between
SPPs and the incident wave that fits well the measured transmitted intensity
profile.Comment: Figure 4 update
All-optical atom surface traps implemented with one-dimensional planar diffractive microstructures
We characterize the loading, containment and optical properties of
all-optical atom traps implemented by diffractive focusing with one-dimensional
(1D) microstructures milled on gold films. These on-chip Fresnel lenses with
focal lengths of the order of a few hundred microns produce
optical-gradient-dipole traps. Cold atoms are loaded from a mirror
magneto-optical trap (MMOT) centered a few hundred microns above the gold
mirror surface. Details of loading optimization are reported and perspectives
for future development of these structures are discussed.Comment: 7 pages, 15 figure
On the mechanism of action of the cytostatic drug anguidine and of the immunosuppressive agent ovalicin, two sesquiterpenes from fungi
CORPORATIONS-OFFICERS AND DIRECTORS-FIDUCIARY DUTY OF OFFICER PURCHASING STOCK FROM SHAREHOLDER
Defendant, president of a corporation acquired stock owned by plaintiff and others by falsely representing that the corporation had been sold. After enhancing the value of this stock, defendant sold it. Plaintiff brought suit for fraudulent conversion and the trial court directed a verdict for the defendant. On appeal, held, reversed. An officer negotiating with a shareholder for the purchase of shares must act with scrupulous trust and confidence, and unless the officer acts with the utmost fairness the wronged shareholder may invoke the proper remedy. Blazer v. Black, (10th Cir. 1952) 196 F. (2d) 139
Study of high voltage solar array configurations with integrated power control electronics
Solar array electrical configurations for voltage regulatio
The Potential and Challenges of Transnational Litigation for Feminist Concerned about Domestic Violence Here and Abroad
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