25,065 research outputs found
Commercial air transport hazard warning and avoidance system. Volume 1 - Summary Final report
Operational requirements for commercial air transport hazard warning and avoidance syste
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The effect of feedback and information on children's pedometer step counts at school
This study examined whether feedback or feedback plus physical activity information could increase the number of pedometer steps taken during 1 school week. One hundred seventy-seven students (mean age 9.124 ± 1.11 years) in three elementary schools participated. Schools were randomly assigned to control (CON), feedback (FB), or feedback plus information (FB+I) groups. Children wore pedometers during school time for 5 consecutive weekdays. The total steps of the groups were recorded at the end of each school day, with students in the FB and FB+I groups free to view their step counts. In addition, the FB+I group received information and ideas about how they could increase their daily steps. The CON group received no step-count feedback or information. Students in the FB+I group achieved significantly more steps per minute (17.17 ± 4.87) than those in the FB (13.77 ± 4.06, p = 0.003) and CON (12.41 ± 3.12, p = 0.0001) groups. Information, as well as step-count feedback, increased elementary students’ school-based physical activity (number of steps) in the short term. A longer intervention period is necessary to assess the sustained impact of this type of approach
Propagation of the 2012 March Coronal Mass Ejections from the Sun to Heliopause
In 2012 March the Sun exhibited extraordinary activities. In particular, the
active region NOAA AR 11429 emitted a series of large coronal mass ejections
(CMEs) which were imaged by STEREO as it rotated with the Sun from the east to
west. These sustained eruptions are expected to generate a global shell of
disturbed material sweeping through the heliosphere. A cluster of shocks and
interplanetary CMEs (ICMEs) were observed near the Earth, and are propagated
outward from 1 AU using an MHD model. The transient streams interact with each
other, which erases memory of the source and results in a large merged
interaction region (MIR) with a preceding shock. The MHD model predicts that
the shock and MIR would reach 120 AU around 2013 April 22, which agrees well
with the period of radio emissions and the time of a transient disturbance in
galactic cosmic rays detected by Voyager 1. These results are important for
understanding the "fate" of CMEs in the outer heliosphere and provide
confidence that the heliopause is located around 120 AU from the Sun.Comment: 13 pages, 5 figures, accepted for publication in ApJ Letter
Parameter estimates for fractional autoregressive spatial processes
A binomial-type operator on a stationary Gaussian process is introduced in
order to model long memory in the spatial context. Consistent estimators of
model parameters are demonstrated. In particular, it is shown that
, where
denotes the long memory parameter.Comment: Published at http://dx.doi.org/10.1214/009053605000000589 in the
Annals of Statistics (http://www.imstat.org/aos/) by the Institute of
Mathematical Statistics (http://www.imstat.org
An Analysis of Whole Farm Revenue Safety Net Options in Agriculture
Despite many years of experience, the federal government continues to seek a farm program that holds the potential for providing a politically acceptable safety net for farmers. This study demonstrates that, with the 2002 Farm Bill, AMTA, and marketing loan provisions continuing, a whole farm revenue safety net has the potential for simplifying existing farm programs, while enhancing the financial position of US farmers. There remains the need for further analysis of the impacts of the options analyzed on supply response by farmers.Agricultural and Food Policy,
IMPACT OF ALTERNATIVE FARM PROGRAMS ON DIFFERENT SIZE COTTON FARMS IN THE TEXAS SOUTHERN HIGH PLAINS: A SIMULATION APPROACH
Eight Texas High Plains cotton farms, ranging in size from 189 acres to 5,570 acres, were simulated under six alternative farm program provisions to determine the likely structural impacts of these programs. The results indicate mid-size farms benefit more from farm programs than either small or large farms since the programs allow them to remain in business. Denying mid-size commercial farms access to the farm program would likely accelerate the trend towards a bimodal distribution of farm sizes on the High Plains.Agribusiness, Crop Production/Industries,
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