760 research outputs found
Application of snowcovered area to runoff forecasting in selected basins of the Sierra Nevada, California
The author has identified the following significant results. Direct overlay onto 1:1,000,000 prints takes about one third the time of 1:500,000 zone transfer scope analysis using transparencies, but the consistency of the transparencies reduce the time for data analysis. LANDSAT data received on transparencies is better and more easily interpreted than the near real-time data from Quick Look, or imagery from other sources such as NOAA. The greatest potential for water supply forecasting is probably in improving forecast accuracy and in expanding forecast services during the period of snowmelt. Problems of transient snow line and uncertainties in future weather are the main reasons that snow cover area appears to offer little in water supply forecast accuracy improvement during the peroid snowpack accumulation
Dynamics of reflection of ultracold atoms from a periodic 1D magnetic lattice potential
We report on an experimental study of the dynamics of the reflection of
ultracold atoms from a periodic one-dimensional magnetic lattice potential. The
magnetic lattice potential of period 10 \textmu m is generated by applying a
uniform bias magnetic field to a microfabricated periodic structure on a
silicon wafer coated with a multilayered TbGdFeCo/Cr magneto-optical film. The
effective thickness of the magnetic film is about 960 nm. A detailed study of
the profile of the reflected atoms as a function of externally induced periodic
corrugation in the potential is described. The effect of angle of incidence is
investigated in detail. The experimental observations are supported by
numerical simulations.Comment: 15 pages, 11 figure
A literature analysis examining the potential suitability of terahertz imaging to detect friction ridge detail preserved in the imprimatura layer of oil-based, painted artwork
This literature analysis examines terahertz (THz) imaging as a non-invasive tool for the imaging of friction ridge detail from the first painted layer (imprimatura) in multilayered painted works of art. The paintings of interest are those created utilizing techniques developed during the Renaissance and still in use today. The goal of analysis serves to answer two questions. First, can THz radiation penetrate paint layers covering the imprimatura to reveal friction ridge information? Secondly, can the this technology
recover friction ridge detail such that the fine details are sufficiently resolved to provide
images suitable for comparison and identification purposes.
If a comparison standard exists, recovered friction ridge detail from this layer can be used to establish linkages to an artist or between works of art. Further, it can be added to other scientific methods currently employed to assist with the authentication efforts of unattributed paintings.
Flanked by the microwave and far-infrared edges, THz straddles the electronic and optic perspectives of the electromagnetic spectrum. As a consequence, this range is imparted with unique and useful properties. Able to penetrate and image through many opaque materials, its non-ionizing radiation is an ideal non-destructive technique that provides visual information from a painting’s sub-strata. Imaging is possible where refractive index differences exist between different paint layers.
Though it is impossible, at present, to determine when a fingerprint was deposited, one can infer approximately when a print was created if it is recovered from the imprimatura layer of a painting, and can be subsequently attributed to a known source. Fingerprints are unique, a person is only able to deposit prints while their physical body is intact and thus, in some cases, the multiple layer process some artists use in their work may be used to the examiner’s advantage.
Impressions of friction ridge detail have been recorded on receiving surfaces from human hands throughout time (and have also been discovered in works of art). Yet, the potential to associate those recorded impressions to a specific individual was only realized just over one hundred years ago. Much like the use of friction ridge skin, the relatively recently discovered THz range is now better understood; its tremendous potential unlocked by growing research and technology designed to exploit its unique properties
Storage and retrieval of light pulses in atomic media with "slow" and "fast" light
We present experimental evidence that light storage, i.e. the controlled
release of a light pulse by an atomic sample dependent on the past presence of
a writing pulse, is not restricted to small group velocity media but can also
occur in a negative group velocity medium. A simple physical picture applicable
to both cases and previous light storage experiments is discussed.Comment: 4 pages, 3 figures, submitted to Physical Review Letter
The use of snowcovered area in runoff forecasts
Long-term snowcovered area data from aircraft and satellite observations have proven useful in reducing seasonal runoff forecast error on the Kern river watershed. Similar use of snowcovered area on the Kings river watershed produced results that were about equivalent to methods based solely on conventional data. Snowcovered area will be most effective in reducing forecast procedural error on watersheds with: (1) a substantial amount of area within a limited elevation range; (2) an erratic precipitation and/or snowpack accumulation pattern not strongly related to elevation; and (3) poor coverage by precipitation stations or snow courses restricting adequate indexing of water supply conditions. When satellite data acquisition and delivery problems are resolved, the derived snowcover information should provide a means for enhancing operational streamflow forecasts for areas that depend primarily on snowmelt for their water supply
Condensate splitting in an asymmetric double well for atom chip based sensors
We report on the adiabatic splitting of a BEC of Rb atoms by an
asymmetric double-well potential located above the edge of a perpendicularly
magnetized TbGdFeCo film atom chip. By controlling the barrier height and
double-well asymmetry the sensitivity of the axial splitting process is
investigated through observation of the fractional atom distribution between
the left and right wells. This process constitutes a novel sensor for which we
infer a single shot sensitivity to gravity fields of . From a simple analytic model we propose improvements
to chip-based gravity detectors using this demonstrated methodology.Comment: 4 pages, 5 figure
Precision measurements of s-wave scattering lengths in a two-component Bose-Einstein condensate
We use collective oscillations of a two-component Bose-Einstein condensate
(2CBEC) of \Rb atoms prepared in the internal states and for the precision measurement of
the interspecies scattering length with a relative uncertainty of
. We show that in a cigar-shaped trap the three-dimensional
(3D) dynamics of a component with a small relative population can be
conveniently described by a one-dimensional (1D) Schr\"{o}dinger equation for
an effective harmonic oscillator. The frequency of the collective oscillations
is defined by the axial trap frequency and the ratio , where
is the intra-species scattering length of a highly populated component
1, and is largely decoupled from the scattering length , the total atom
number and loss terms. By fitting numerical simulations of the coupled
Gross-Pitaevskii equations to the recorded temporal evolution of the axial
width we obtain the value , where is the Bohr
radius. Our reported value is in a reasonable agreement with the theoretical
prediction but deviates significantly from the
previously measured value \cite{Mertes07} which is commonly
used in the characterisation of spin dynamics in degenerate \Rb atoms. Using
Ramsey interferometry of the 2CBEC we measure the scattering length
which also deviates from the previously reported value
\cite{Mertes07}. We characterise two-body losses for the
component 2 and obtain the loss coefficients
and
.Comment: 11 pages, 8 figure
Resilience does matter: evidence from a 10-year cohort record linkage study
OBJECTIVES: To examine 10-year mortality and hospital use among individuals categorised as resilient and vulnerable to the impact of chronic pain. DESIGN: A cohort record linkage study. SETTING: Grampian, Scotland. PARTICIPANTS: 5858 individuals from the Grampian Pain Cohort, established in 1996, were linked, by probability matching, with national routinely collected datasets. MAIN OUTCOME MEASURES: HRs for subsequent 10-year mortality and ORs/incidence rate ratios for subsequent 10-year hospital use, each with adjustment for potential confounding variables. RESULTS: 36.5% of those with high pain intensity reported a low pain-related disability (categorised resilient) and 7.1% of those reporting low pain intensity reported a high pain-related disability (categorised vulnerable). Sex, age, housing, employment and long-term limiting illness were independently associated with being vulnerable or resilient. After adjustment for these variables, individuals in the resilient group were 25% less likely to die within 10 years of the survey compared with non-resilient individuals: HR 0.75, 95% CI 0.62 to 0.91 and vulnerable individuals were 45% more likely to die than non-vulnerable individuals: HR 1.45, 95% CI 1.01 to 2.11. Resilient individuals were less likely to have had an outpatient or day-case visit for anaesthetics: OR 0.46, 95% CI 0.27 to 0.79, but no other clinical specialities. Vulnerable individuals were significantly less likely to have had any outpatient or day-case visit (OR 0.43, 0.25 to 0.75); but more likely to have had a psychiatric visit (OR 1.96, 1.06 to 3.61). No significant differences in likelihood of any inpatient visits were found. CONCLUSIONS: Resilient individuals have a better 10-year survival than non-resilient individuals indicating that resilience is a phenomenon worth researching. Further research is needed to explore who is likely to become resilient, why and how, as well as to tease out the internal and external factors that influence resilience
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