1,833 research outputs found
Packaging techniques for low-altitude Venus balloons beacon
The results of a specific design project for the Venus balloon beacon, in which a microwave beacon is required to operate for a limited time at high temperature (350 C) and at high pressure, (10 bars). In a chemically hostile environment after surviving large mechanical shock forces (up to 280 gs) are discussed. It was found that many existing, commerically-available component can be used in such a design with only minor modifications. A further result is that a crude (and consequently low-cost) test program can be designed to identify and select promising commercial components
Measurement of Surface Crack Opening Displacements Using Microwave Frequency Eddy Currents
An electromagnetic NDE technique for measuring the crack opening displacement of surface fatigue cracks is described. A ferromagnetic resonance probe utilizing yttrium-iron-garnet was used to induce eddy currents in an aluminum plate. The crack opening disolacement of a semi-elliptical fatigue crack evaluated at the surface was measured optically at several values of bending stress on the specimen. A technique is presented which allows the crack depth to be calculated from the measured COD at a given stress. The relative phase and magnitude of input vs. output signal to and from the resonating YIG sphere was recorded during the interaction of the FMR probe eddy currents and the fatigue crack. A method is shown to extract quantitative information from these signals and to correlate this information with the crack opening displacement
Preventing Running Injuries Using a Pre-Running Exercise Program (PREP): A Pilot Study
Hypothesis: An 8 week supervised PREP implemented prior to a 5k running program will reduce the incidence of RRI\u27s among novice runners training for a 5k below the previously published incidence rates
Forecasting Periods of Strong Southward Magnetic Field Following Interplanetary Shocks
Long periods of strong southward magnetic fields are known to be the primary
cause of intense geomagnetic storms. The majority of such events are caused by
the passage over Earth of a magnetic ejecta. Irrespective of the interplanetary
cause, fast-forward shocks often precede such strong southward B periods.
Here, we first look at all long periods of strong southward magnetic fields as
well as fast-forward shocks measured by the \textit{Wind} spacecraft in a
22.4-year span. We find that 76{\%} of strong southward B periods are
preceded within 48 hours by at least a fast-forward shock but only about 23{\%}
of all shocks are followed within 48 hours by strong southward B periods.
Then, we devise a threshold-based probabilistic forecasting method based on the
shock properties and the pre-shock near-Earth solar wind plasma and
interplanetary magnetic field characteristics adopting a `superposed epoch
analysis'-like approach. Our analysis shows that the solar wind conditions in
the 30 minutes interval around the arrival of fast-forward shocks have a
significant contribution to the prediction of long-duration southward B
periods. This probabilistic model may provide on average a 14-hour warning time
for an intense and long-duration southward B period. Evaluating the
forecast capability of the model through a statistical and skill score-based
approach reveals that it outperforms a coin-flipping forecast. By using the
information provided by the arrival of a fast-forward shock at L1, this model
represents a marked improvement over similar forecasting methods. We outline a
number of future potential improvements.Comment: published in Space Weather, 22 Nov 201
The views of older women towards mammographic screening: a qualitative and quantitative study
Purpose: Mammographic screening has improved breast cancer survival in the screened age group. This improved survival has not been seen in older women (>70 years) where screening uptake is low. This study explores the views, knowledge and attitudes of older women towards screening.
Methods: Women (>70) were interviewed about breast screening. Interview findings informed the development of a questionnaire which was sent to 1000 women (>70) to quantify their views regarding screening.
Results: Twenty-six women were interviewed and a questionnaire designed. The questionnaire response rate was 48.3% (479/992). Over half (52.9%, 241/456) of respondents were unaware they could request mammography by voluntary self-referral and were unaware of how to arrange this. Most (81.5% 383/470) had not attended breast screening since turning 70. Most (75.6%, 343/454) felt screening was beneficial and would attend if invited. Most, (90.1%, 412/457) felt screening should be offered to all women regardless of age or health.
Conclusions: There is a lack of knowledge about screening in older women. The majority felt that invitation to screening should be extended to the older age group regardless of age or health. The current under-utilised system of voluntary self referral is not supported by older women
Mercury's Surface Magnetic Field Determined from Proton-Reflection Magnetometry
Solar wind protons observed by the MESSENGER spacecraft in orbit about Mercury exhibit signatures of precipitation loss to Mercury's surface. We apply proton-reflection magnetometry to sense Mercury's surface magnetic field intensity in the planet's northern and southern hemispheres. The results are consistent with a dipole field offset to the north and show that the technique may be used to resolve regional-scale fields at the surface. The proton loss cones indicate persistent ion precipitation to the surface in the northern magnetospheric cusp region and in the southern hemisphere at low nightside latitudes. The latter observation implies that most of the surface in Mercury's southern hemisphere is continuously bombarded by plasma, in contrast with the premise that the global magnetic field largely protects the planetary surface from the solar wind
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