221 research outputs found
Can Survey-based Scenarios Measure Consumer Values for Improved Food Safety?
Demand and Price Analysis, Food Consumption/Nutrition/Food Safety,
A study of fluid overpressure microstructures from the creeping segment of the San Andreas fault
Evidence of episodic fluid overpressure events noted in samples from the San Andreas Fault Observatory at Depth (SAFOD) have remained largely uncorrelated in terms of their collective significance for seismic history of the fault zone. The compositional and microstructural correlations sought in this study could shed light on questions about potential for major seismic events in the creeping segment of the SAF in central California. We used quantitative energy dispersive spectroscopy (EDS), Cathodoluminescence (CL) and Scanning Electron Microscope (SEM) imaging, and electron backscatter diffraction (EBSD) analysis to acquire geochemical and microstructural data from a suite of twenty SAFOD core samples including the damage zone and the active core of the fault. The results indicate intermittent coseismic fluid overpressure events that overprint the background aseismic creep across the fault. Analysis of trace elements and deformation in the coseismic calcite vein generations and their associated hydrothermal mineral phases indicate progressive uplift and exhumation followed by an asymmetric incursion of meteoric water into the damage zone. The same analysis suggests that the actively creeping intervals act as permeability barriers. Our results are in overall agreement with recent studies of the SAF in central California that indicate large seismic events have occurred intermittent with aseismic creep in recent geological time or suggest future potential for such events
'Magic coins' and 'magic squares': the discovery of astrological sigils in the Oldenburg Letters
Enclosed in a 1673 letter to Henry Oldenburg were two drawings of a series of astrological sigils, coins and amulets from the collection of Strasbourg mathematician Julius Reichelt (1637–1719). As portrayals of particular medieval and early modern sigils are relatively rare, this paper will analyse the role of these medals in medieval and early modern medicine, the logic behind their perceived efficacy, and their significance in early modern astrological and cabalistic practice. I shall also demonstrate their change in status in the late seventeenth century from potent magical healing amulets tied to the mysteries of the heavens to objects kept in a cabinet for curiosos. The evolving perception of the purpose of sigils mirrored changing early modern beliefs in the occult influences of the heavens upon the body and the natural world, as well as the growing interests among virtuosi in collecting, numismatics and antiquities
Colors of 2625 Quasars at 0<z<5 Measured in the Sloan Digital Sky Survey Photometric System
We present an empirical investigation of the colors of quasars in the Sloan
Digital Sky Survey (SDSS) photometric system. The sample studied includes 2625
quasars with SDSS photometry. The quasars are distributed in a 2.5 degree wide
stripe centered on the Celestial Equator covering square degrees.
Positions and SDSS magnitudes are given for the 898 quasars known prior to SDSS
spectroscopic commissioning. New SDSS quasars represent an increase of over
200% in the number of known quasars in this area of the sky. The ensemble
average of the observed colors of quasars in the SDSS passbands are well
represented by a power-law continuum with (). However, the contributions of the bump
and other strong emission lines have a significant effect upon the colors. The
color-redshift relation exhibits considerable structure, which may be of use in
determining photometric redshifts for quasars. The range of colors can be
accounted for by a range in the optical spectral index with a distribution
(95% confidence), but there is a red tail in the
distribution. This tail may be a sign of internal reddening. Finally, we show
that there is a continuum of properties between quasars and Seyfert galaxies
and we test the validity of the traditional division between the two classes of
AGN.Comment: 66 pages, 15 figures (3 color), accepted by A
First search for gravitational waves from the youngest known neutron star
We present a search for periodic gravitational waves from the neutron star in the supernova remnant Cassiopeia
A. The search coherently analyzes data in a 12 day interval taken from the fifth science run of the Laser
Interferometer Gravitational-Wave Observatory. It searches gravitational-wave frequencies from 100 to 300 Hz
and covers a wide range of first and second frequency derivatives appropriate for the age of the remnant and
for different spin-down mechanisms. No gravitational-wave signal was detected. Within the range of search
frequencies, we set 95% confidence upper limits of (0.7–1.2) × 10^(−24) on the intrinsic gravitational-wave
strain, (0.4–4) × 10^(−4) on the equatorial ellipticity of the neutron star, and 0.005–0.14 on the amplitude of
r-mode oscillations of the neutron star. These direct upper limits beat indirect limits derived from energy
conservation and enter the range of theoretical predictions involving crystalline exotic matter or runaway r-modes.
This paper is also the first gravitational-wave search to present upper limits on the r-mode amplitude
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