8,910 research outputs found
Microwave responses of the western North Atlantic
Features and objects in the Western North Atlantic Ocean - the Eastern Seaboard of the United States - are observed from Earth orbit by passive microwaves. The intensities of their radiated flux signatures are measured and displayed in color as a microwave flux image. The features of flux emitting objects such as the course of the Gulf Stream and the occurrence of cold eddies near the Gulf Stream are identified by contoured patterns of relative flux intensities. The flux signatures of ships and their wakes are displayed and discussed. Metal data buoys and aircraft are detected. Signal to clutter ratios and probabilities of detection are computed from their measured irradiances. Theoretical models and the range equations that explain passive microwave detection using the irradiances of natural sources are summarized
Microwave hydrology: A trilogy
Microwave hydrology, as the term in construed in this trilogy, deals with the investigation of important hydrological features on the Earth's surface as they are remotely, and passively, sensed by orbiting microwave receivers. Microwave wavelengths penetrate clouds, foliage, ground cover, and soil, in varying degrees, and reveal the occurrence of standing liquid water on and beneath the surface. The manifestation of liquid water appearing on or near the surface is reported by a microwave receiver as a signal with a low flux level, or, equivalently, a cold temperature. Actually, the surface of the liquid water reflects the low flux level from the cosmic background into the input terminals of the receiver. This trilogy describes and shows by microwave flux images: the hydrological features that sustain Lake Baykal as an extraordinary freshwater resource; manifestations of subsurface water in Iran; and the major water features of the Congo Basin, a rain forest
Search for correlation effects in linear chains of trapped ions
We report a precise search for correlation effects in linear chains of 2 and
3 trapped Ca+ ions. Unexplained correlations in photon emission times within a
linear chain of trapped ions have been reported, which, if genuine, cast doubt
on the potential of an ion trap to realize quantum information processing. We
observe quantum jumps from the metastable 3d 2D_{5/2} level for several hours,
searching for correlations between the decay times of the different ions. We
find no evidence for correlations: the number of quantum jumps with separations
of less than 10 ms is consistent with statistics to within errors of 0.05%; the
lifetime of the metastable level derived from the data is consistent with that
derived from independent single-ion data at the level of the experimental
errors 1%; and no rank correlations between the decay times were found with
sensitivity to rank correlation coefficients at the level of |R| = 0.024.Comment: With changes to introduction. 5 pages, including 4 figures. Submitted
to Europhys. Let
The Local Environments of Core-Collapse SNe within Host Galaxies
We present constraints on core-collapse supernova progenitors through
observations of their environments within host galaxies. This is achieved
through 2 routes. Firstly, we investigate the spatial correlation of supernovae
with host galaxy star formation using pixel statistics. We find that the main
supernova types form a sequence of increasing association to star formation.
The most logical interpretation is that this implies an increasing progenitor
mass sequence going from the supernova type Ia arising from the lowest mass,
through the type II, type Ib, and the supernova type Ic arising from the
highest mass progenitors. We find the surprising result that the supernova type
IIn show a lower association to star formation than type IIPs, implying lower
mass progenitors. Secondly, we use host HII region spectroscopy to investigate
differences in environment metallicity between different core-collapse types.
We find that supernovae of types Ibc arise in slightly higher metallicity
environments than type II events. However, this difference is not significant,
implying that progenitor metallicity does not play a dominant role in deciding
supernova type.Comment: to appear in Proceedings of IAU 279 "Death of Massive Stars:
Supernovae and Gamma-ray Bursts
A Pilot Study Of The Prevalence Of Leg Pain Among Women With Endometriosis
Radiating leg pain is a common symptom presenting in manual therapy practices. Although this symptom has been reported as a complication of endometriosis, its prevalence and characteristics have not been studied. We surveyed members of a national endometriosis support group with endometriosis using a self-administered, mailed questionnaire. The main outcome measures were the prevalence and characteristics of leg pain. Of 94 respondents, leg pain was reported by 48 women (51%), and was bilateral in 59% of these symptomatic women. The likelihood of experiencing leg pain was related to weight gain since age 18, age, and height. The most common treatments tried included exercise, over-the-counter medications, and massage therapy, all with variable results. These data support leg pain as a prevalent complication of endometriosis, and that the disease may affect multiple peripheral nerves. Manual therapists should remain aware to this possible etiology for radiating pain
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