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Sand Penetration By High-Speed Projectiles
Tungsten projectiles were shot into sand at velocities between 600 and 2200 m/s. Penetration was maximum at about 775 m/s. Below that velocity, projectiles were apparently stabilized by a fin set. Above that velocity, projectiles were broken by transverse loads. High-speed penetration resulted in comminution of sand particles, reducing their size by about 1000 times.Mechanical Engineerin
Geophysical Research
Contains reports on two research projects.Joint Services Electronics Programs (U. S. Army, U. S. Navy, and U. S. Air Force) under Contract DA 28-043-AMC-02536(E)National Aeronautics and Space Administration (Grant NGR-22-009-131)National Aeronautics and Space Administration (Grant NGR-22-009-114)National Aeronautics and Space Administration (Contract NAS 12-436
The Hubble Space Telescope high speed photometer
The Hubble Space Telescope will provide the opportunity to perform precise astronomical photometry above the disturbing effects of the atmosphere. The High Speed Photometer is designed to provide the observatory with a stable, precise photometer with wide dynamic range, broad wavelenth coverage, time resolution in the microsecond region, and polarimetric capability. Here, the scientific requirements for the instrument are examined, the unique design features of the photometer are explored, and the improvements to be expected over the performance of ground-based instruments are projected
Policy opportunities
Recommendations are given regarding National Science Foundation (NSF) astronomy programs and the NASA Space Astrophysics program. The role of ground based astronomy is reviewed. The role of National Optical Astronomy Observatories (NOAO) in ground-based night-time astronomical research is discussed. An enhanced Explored Program, costs and management of small and moderate space programs, the role of astrophysics within NASA's space exploration initiative, suborbital and airborne astronomical research, the problems of the Hubble Space Telescope, and astronomy education are discussed. Also covered are policy issues related to the role of science advisory committees, international cooperation and competition, archiving and distribution of astronomical data, and multi-wavelength observations of variable sources
Hubble Space Telescope: A cosmic time machine
The mission of the Hubble Space Telescope (HST) is to explore the expanding and evolving universe. During the 3,000 operating hours every year for the next 15 years or more, the HST will be used to study: galaxies; pulsars; globular clusters; neighboring stars where planets may be forming; binary star systems; condensing gas clouds and their chemical composition; and the rings of Saturn and the swirling ultraviolet clouds of Venus. The major technical achievements - its nearly perfect mirrors, its precise guidance system of rate gyroscopes, reaction wheels, star trackers, and fine guidance sensors are briefly discussed. The scientific instruments on board HST are briefly described. The integration of the equipment and instruments is outlined. The Space Telescope Science Institute (STScI) has approved time for 162 observations from among 556 proposals. The mission operation and data flow are explained
Diverse earliest Triassic ostracod fauna of the non-microbialite-bearing shallow marine carbonates of the Yangou section, South China
Emotion and memory: Event-related potential indices predictive for subsequent successful memory depend on the emotional mood state.
The present research investigated the influencesof emotional mood states on
cognitive processes and neural circuits during long-term memory encoding using
event-related potentials (ERPs). We assessed whether the subsequent memory
effect (SME), an electrophysiological index of successful memory encoding,
varies as a function of participants’ current mood state. ERPs were recorded
while participants in good or bad mood states were presented with words that had
to be memorized for subsequent recall. In contrast to participants in bad mood,
participants in good mood most frequently applied elaborative encoding styles.
At the neurophysiological level, ERP analyses showed that potentials to
subsequently recalled words were more positive than to forgotten words at
central electrodes in the time interval of 500-650 ms after stimulus onset
(SME). At fronto-central electrodes, a polarity-reversed SME was obtained. The
strongest modulations of the SME by participants’ mood state were obtained at
fronto-temporal electrodes. These differences in the scalp topography of the SME
suggest that successful recall relies on partially separable neural circuits for
good and bad mood states. The results are consistent with theoretical accounts
of the interface between emotion and cognition that propose mood-dependent
cognitive styles
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