32,140 research outputs found
Multispectral and geomorphic studies of processed Voyager 2 images of Europa
High resolution images of Europa taken by the Voyager 2 spacecraft were used to study a portion of Europa's dark lineations and the major white line feature Agenor Linea. Initial image processing of images 1195J2-001 (violet filter), 1198J2-001 (blue filter), 1201J2-001 (orange filter), and 1204J2-001 (ultraviolet filter) was performed at the U.S.G.S. Branch of Astrogeology in Flagstaff, Arizona. Processing was completed through the stages of image registration and color ratio image construction. Pixel printouts were used in a new technique of linear feature profiling to compensate for image misregistration through the mapping of features on the printouts. In all, 193 dark lineation segments were mapped and profiled. The more accurate multispectral data derived by this method was plotted using a new application of the ternary diagram, with orange, blue, and violet relative spectral reflectances serving as end members. Statistical techniques were then applied to the ternary diagram plots. The image products generated at LPI were used mainly to cross-check and verify the results of the ternary diagram analysis
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Using data from connected thermostats to track large power outages in the United States
The detection of power outages is an essential activity for electric utilities. A large, national dataset of Internet-connected thermostats was used to explore and illustrate the ability of Internet-connected devices to geospatially track outages caused by hurricanes and other major weather events. The method was applied to nine major outage events, including hurricanes and windstorms. In one event, Hurricane Irma, a network of about 1000 thermostats provided quantitatively similar results to detailed utility data with respect to the number of homes without power and identification of the most severely affected regions. The method generated regionally uniform outage data that would give emergency authorities additional visibility into the scope and magnitude of outages. The network of thermostat-sensors also made it possible to calculate a higher resolution version of outage duration (or SAIDI) at a level of customer-level visibility that was not previously available
Effects of Hyperbaric Hypoxia on Some Enzyme Systems in the Mammalian Liver
The metabolic effects of hypobaric hypoxic stress on the mammalian liver were studied. The lactate dehydrogenase (LDH) and succinate dehydrogenase (SDH) activity of mouse liver homogenates were measured after exposure to an equivalent altitude of 36,000 feet and compared to controls kept at zero altitude. After six and twelve hour incubation periods, the altitude exposed samples demonstrated a significantly higher LDH activity than controls. SDH activity remained unchanged from controls after six hours but was significantly lower than controls after a 12 hour exposure to altitude. It is concluded that the changes in enzyme activity reflect a metabolic control mechanism attempting to maintain adequate energy production during periods of exposure to hypobaric hypoxic stress
Dynamics of Quantum Dot Nuclear Spin Polarization Controlled by a Single Electron
We present an experimental study of the dynamics underlying the buildup and
decay of dynamical nuclear spin polarization in a single semiconductor quantum
dot. Our experiment shows that the nuclei can be polarized on a time scale of a
few milliseconds, while their decay dynamics depends drastically on external
parameters. We show that a single electron can very efficiently depolarize the
nuclear spins and discuss two processes that can cause this depolarization.
Conversely, in the absence of a quantum dot electron, the lifetime of nuclear
spin polarization is on the time scale of a second, most likely limited by the
non-secular terms of the nuclear dipole-dipole interaction. We can further
suppress this depolarization rate by 1-2 orders of magnitude by applying an
external magnetic field exceeding 1 mT.Comment: 5 pages, 3 figure
Costly Inflation Misperceptions
One of the consequences of the euro changeover in 2002 was that for a period of several years people considerably overestimated actual inflation. The goal of this paper is to study whether misperceptions of this kind may have real effects, that is, whether they induce people to alter their behaviour. We also discuss the question how far the euro changeover and the ensuing discussion about price stability contributed to the recession that followed the changeover. Looking at the German restaurant sector, we find that people’s misperceptions can have significant negative effects. The contraction this sector experienced in the months after the changeover was too pronounced to be explained by normal business cycle movements. We provide a discussion about the causes of these misperceptions and how to avoid them in future changeovers.euro changeover, perceived inflation
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