276 research outputs found
Airborne Science Program: Observing Platforms for Earth Science Investigations
This slide presentation reviews the Airborne Science Program and the platforms used for conducting investigations for the Earth System Science. Included is a chart that shows some of the aircraft and the operational altitude and the endurance of the aircraft, views of the Dryden Aircraft Operation Facility, and some of the current aircraft that the facility operates, and the varieties of missions that are flown and the type of instrumentation. Also included is a chart showing the attributes of the various aircraft (i.e., duration, weight for a payload, maximum altitude, airspeed and range) for compariso
Global Test Range: Toward Airborne Sensor Webs
This viewgraph presentation reviews the planned global sensor network that will monitor the Earth's climate, and resources using airborne sensor systems. The vision is an intelligent, affordable Earth Observation System. Global Test Range is a lab developing trustworthy services for airborne instruments - a specialized Internet Service Provider. There is discussion of several current and planned missions
Ancient Egypt 1921 Part 1
Part 1 of the 1921 Ancient Egypt books. Contents include the alphabet in the XIIth dynasty, the Lahun caskets, burial rites of West Africa, a Negro captive, and Queen Tetisheri.https://knowledge.e.southern.edu/kweeks_coll/1014/thumbnail.jp
Resonant transmission through an open quantum dot
We have measured the low-temperature transport properties of a quantum dot
formed in a one-dimensional channel. In zero magnetic field this device shows
quantized ballistic conductance plateaus with resonant tunneling peaks in each
transition region between plateaus. Studies of this structure as a function of
applied perpendicular magnetic field and source-drain bias indicate that
resonant structure deriving from tightly bound states is split by Coulomb
charging at zero magnetic field.Comment: To be published in Phys. Rev. B (1997). 8 LaTex pages with 5 figure
Interaction Effects in a One-Dimensional Constriction
We have investigated the transport properties of one-dimensional (1D)
constrictions defined by split-gates in high quality GaAs/AlGaAs
heterostructures. In addition to the usual quantized conductance plateaus, the
equilibrium conductance shows a structure close to , and in
consolidating our previous work [K.~J. Thomas et al., Phys. Rev. Lett. 77, 135
(1996)] this 0.7 structure has been investigated in a wide range of samples as
a function of temperature, carrier density, in-plane magnetic field
and source-drain voltage . We show that the 0.7
structure is not due to transmission or resonance effects, nor does it arise
from the asymmetry of the heterojunction in the growth direction. All the 1D
subbands show Zeeman splitting at high , and in the wide channel
limit the -factor is , close to that of bulk GaAs.
As the channel is progressively narrowed we measure an exchange-enhanced
-factor. The measurements establish that the 0.7 structure is related to
spin, and that electron-electron interactions become important for the last few
conducting 1D subbands.Comment: 8 pages, 7 figures (accepted in Phys. Rev. B
Spitzer Photometry of WISE-Selected Brown Dwarf and Hyper-Luminous Infrared Galaxy Candidates
We present Spitzer 3.6 and 4.5 m photometry and positions for a sample
of 1510 brown dwarf candidates identified by the WISE all-sky survey. Of these,
166 have been spectroscopically classified as objects with spectral types M(1),
L(7), T(146), and Y(12); Sixteen other objects are non-(sub)stellar in nature.
The remainder are most likely distant L and T dwarfs lacking spectroscopic
verification, other Y dwarf candidates still awaiting follow-up, and assorted
other objects whose Spitzer photometry reveals them to be background sources.
We present a catalog of Spitzer photometry for all astrophysical sources
identified in these fields and use this catalog to identify 7 fainter (4.5
m 17.0 mag) brown dwarf candidates, which are possibly wide-field
companions to the original WISE sources. To test this hypothesis, we use a
sample of 919 Spitzer observations around WISE-selected high-redshift
hyper-luminous infrared galaxy (HyLIRG) candidates. For this control sample we
find another 6 brown dwarf candidates, suggesting that the 7 companion
candidates are not physically associated. In fact, only one of these 7 Spitzer
brown dwarf candidates has a photometric distance estimate consistent with
being a companion to the WISE brown dwarf candidate. Other than this there is
no evidence for any widely separated ( 20 AU) ultra-cool binaries. As an
adjunct to this paper, we make available a source catalog of 7.33
objects detected in all of these Spitzer follow-up fields for use
by the astronomical community. The complete catalog includes the Spitzer 3.6
and 4.5 m photometry, along with positionally matched and
photometry from USNO-B; , , and photometry from 2MASS; and ,
, , and photometry from the WISE all-sky catalog
Industrial energy use and the human life history
The demographic rates of most organisms are supported by the consumption of food energy, which is used to produce new biomass and fuel physiological processes. Unlike other species, modern humans use ‘extra-metabolic' energy sources acquired independent of physiology, which also influence demographics. We ask whether the amount of extra-metabolic energy added to the energy budget affects demographic and life history traits in a predictable way. Currently it is not known how human demographics respond to energy use, and we characterize this response using an allometric approach. All of the human life history traits we examine are significant functions of per capita energy use across industrialized populations. We find a continuum of traits from those that respond strongly to the amount of extra-metabolic energy used, to those that respond with shallow slopes. We also show that the differences in plasticity across traits can drive the net reproductive rate to below-replacement levels
Measurement of water colour using AVIRIS imagery to assess the potential for an operational monitoring capability in the Pamlico Sound Estuary, USA
The monitoring of water colour parameters can provide an important diagnostic tool for the assessment of aquatic ecosystem condition. Remote sensing has long been used to effectively monitor chlorophyll concentrations in open ocean systems; however, operational monitoring in coastal and estuarine areas has been limited because of the inherent complexities of coastal systems, and the coarse spectral and spatial resolutions of available satellite systems. Data were collected using the National Aeronautics and Space Administration (NASA) Advanced Visible-Infrared Imaging Spectrometer (AVIRIS) flown at an altitude of approximately 20000 m to provide hyperspectral imagery and simulate both MEdium Resolution Imaging Spectrometer (MERIS) and Moderate Resolution Imaging Spectrometer (MODIS) data. AVIRIS data were atmospherically corrected using a radiative transfer modelling approach and analysed using band ratio and linear regression models. Regression analysis was performed with simultaneous field measurements data in the Neuse River Estuary (NRE) and Pamlico Sound on 15 May 2002. Chlorophyll a (Chl a) concentrations were optimally estimated using AVIRIS bands (9.5 nm) centred at 673.6 and 692.7 nm, resulting in a coefficient of determination (R2) of 0.98. Concentrations of Chromophoric Dissolved Organic Matter (CDOM), Total Suspended Solids (TSS) and Fixed Suspended Solids (FSS) were also estimated, resulting in coefficients of determination of R2=0.90, 0.59 and 0.64, respectively. Ratios of AVIRIS bands centred at or near those corresponding to the MERIS and MODIS sensors indicated that relatively good satellite-based estimates could potentially be derived for water colour constituents at a spatial resolution of 300 and 500 m, respectively
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