206 research outputs found
Faculty Views of “Nontraditional” Students: Aligning Perspectives for Student Success
Faculty serve as a primary point of contact for students in college, playing vital roles in students’ retention and attainment. The perceptions and beliefs held by these institutional actors are important for understanding the context that shapes students’ experiences while they are in college and potentially, long after they leave. The purpose of this work is to examine faculty members’ perceptions of nontraditional student experiences. Findings highlight faculty members’ awareness of students’ multiple roles and obligations; perceptions of student academic success, including barriers to succeeding; and the ways faculty connect with students and the types of connections they forge. The findings from this work highlight the need to consider more research on how the experiences of students who do not fit a traditional model are interpreted by those in positions of power at higher education institutions. As such, we add to calls for more work that considers these institutional actors explicitly and how they shape student success
Development of a 2009 Stable Lights Product using DMSP-OLS data
Since 1994, NGDC has had an active program focused on global mapping of nighttime lights using the data collected by the Defense Meteorological Satellite Program’s Operational Linescan System (DMSP-OLS) sensors. The basic product is a global annual cloud-free composite, which averages the OLS visible band data for one satellite from the cloud-free segments of individual orbits. Over the years, NGDC has developed automatic algorithms for screening the quality of the nighttime visible band observations to remove areas contaminated by sunlight, moonlight, and the presence of clouds. In the Stable Lights product generation, fires and other ephemeral lights are removed based on their high brightness and short duration. Background noise is removed by setting thresholds based on visible band values found in areas known to be free of detectable lights. In 2010, NGDC released the version 4 time series of Stable Lights, spanning the years 1992-2009. These are available online at <http://www.ngdc.noaa.gov/dmsp/downloadV4composites.html>
Methods Used For the 2006 Radiance Lights
The Operational Linescan System (OLS) flown on the Defense Meteorological Satellite Program (DMSP) satellites, has a unique capability to record low light imaging data at night worldwide. These data are archived at the National Oceanic and Atmospheric Administration (NOAA) National Geophysical Data Center (NGDC). The useful data record stretches back to 1992 and is ongoing. The OLS visible band detector observes radiances about one million times dimmer than most other Earth observing satellites. The sensor is typically operated in a high gain setting to enable the detection of moonlit clouds. However, with six bit quantization and limited dynamic range, the recorded data are saturated in the bright cores of urban centers. A limited set of observations have been obtained at low lunar illumination were obtained where the gain of the detector was set significantly lower than its typical operational setting (sometimes by a factor of 100). By combining these sparse data acquired at low gain settings with the operational data acquired at high gain settings, we have produced a global nighttime lights product for 2006 with no sensor saturation. This product can be related to radiances based on the pre-flights sensor calibration
Mapping the Constructed Surface Area Density for China
Efforts to map the constructed surface area density of the world using nighttime satellite imagery have typically been validated using aerial photography or high resolution satellite imagery in the United States and extrapolating regression parameters to countries outside of the United States. In a previous study, we found China to have ‘paved’ more of the planet than any other country (~87,00 km2). Here we use a google earth based web application to validate our estimates of anthropogenic impervious surface (constructed area density) in China using actual imagery of China. ‘Paving the Planet’ is a universal phenomenon – akin to clothing – and represents one of the primary anthropogenic modifications of the environment. Expansion in population numbers and economies combined with the increased use of automobiles has led to the sprawl of development and a wide proliferation of constructed impervious surfaces. Constructed impervious surfaces are both hydrological and ecological disturbances. However, constructed surfaces are different from most other types of disturbances in that recovery is arrested through the use of materials that are resistant to decay and are actively maintained. The same characteristics that make impervious surfaces ideal for use in construction produce a series of effects on the environment. We present a new map of the density of constructed surface in China derived from DMSP nighttime lights and LandScan population count data
TERRA/MOPITT Measurements of Tropospheric Carbon Monoxide Distributions in Support of INTEX
Interaction with the ongoing satellite measurements programs was an important goal of INTEX- A. The Terra/MOPITT instrument had been making global measurements of the tropospheric carbon monoxide (CO) distribution for 4 years, and was in a unique position to provide valuable support during the field campaign. Remote sensing of CO directly addressed the scientific questions motivating the IXTEX-A strategy and deployment, and measurement of this gas was rated as being mission critical. CO is an important trace gas in tropospheric chemistry due to its role in determining the atmospheric oxidizing capacity, as an ozone precursor, and as an indicator and tracer of both natural and anthropogenic pollution arising from incomplete combustion. The satellite perspective provided the more general temporal and spatial context to the aircraft and ground-based measurements during the subsequent scientific analysis. We proposed to build on the experience of supplying MOPITT data to previous field campaigns, such as TRACE-P. We provided expedited MOPITT data processing in near real-time, along with basic analysis of the measurements to indicate, where possible, the origin of the CO plumes that impacted the regions of flight operations and other in situ measurement activities. To ensure maximum exploitation of the satellite information, we will also had a scientist in the field to present and interpret the MOPITT data for the INTEX team, and to help ensure its utility in flight planning
Measurements of electron-proton elastic cross sections for
We report on precision measurements of the elastic cross section for
electron-proton scattering performed in Hall C at Jefferson Lab. The
measurements were made at 28 unique kinematic settings covering a range in
momentum transfer of 0.4 5.5 . These measurements
represent a significant contribution to the world's cross section data set in
the range where a large discrepancy currently exists between the ratio of
electric to magnetic proton form factors extracted from previous cross section
measurements and that recently measured via polarization transfer in Hall A at
Jefferson Lab.Comment: 17 pages, 18 figures; text added, some figures replace
Longitudinal-Transverse Separations of Structure Functions at Low for Hydrogen and Deuterium
We report on a study of the longitudinal to transverse cross section ratio,
, at low values of and , as determined from
inclusive inelastic electron-hydrogen and electron-deuterium scattering data
from Jefferson Lab Hall C spanning the four-momentum transfer range 0.06 GeV. Even at the lowest values of , remains
nearly constant and does not disappear with decreasing , as expected. We
find a nearly identical behaviour for hydrogen and deuterium.Comment: 4 pages, 2 gigure
The Charge Form Factor of the Neutron at Low Momentum Transfer from the Reaction
We report new measurements of the neutron charge form factor at low momentum
transfer using quasielastic electrodisintegration of the deuteron.
Longitudinally polarized electrons at an energy of 850 MeV were scattered from
an isotopically pure, highly polarized deuterium gas target. The scattered
electrons and coincident neutrons were measured by the Bates Large Acceptance
Spectrometer Toroid (BLAST) detector. The neutron form factor ratio
was extracted from the beam-target vector asymmetry
at four-momentum transfers , 0.20, 0.29 and 0.42
(GeV/c).Comment: 5 pages, 3 figures, submitted to Phys. Rev. Let
Measurement of the proton electric to magnetic form factor ratio from \vec ^1H(\vec e, e'p)
We report the first precision measurement of the proton electric to magnetic
form factor ratio from spin-dependent elastic scattering of longitudinally
polarized electrons from a polarized hydrogen internal gas target. The
measurement was performed at the MIT-Bates South Hall Ring over a range of
four-momentum transfer squared from 0.15 to 0.65 (GeV/c).
Significantly improved results on the proton electric and magnetic form factors
are obtained in combination with previous cross-section data on elastic
electron-proton scattering in the same region.Comment: 4 pages, 2 figures, submitted to PR
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