1,880 research outputs found
Rhythmic Micro-Gestures: Discreet Interaction On-the-Go
We present rhythmic micro-gestures, micro-movements of the hand that are repeated in time with a rhythm. We present a user study that investigated how well users can perform rhythmic micro-gestures and if they can use them eyes-free with non-visual feedback. We found that users could successfully use our interaction technique (97% success rate across all gestures) with short interaction times, rating them as low difficulty as well. Simple audio cues that only convey the rhythm outperformed animations showing the hand movements, supporting rhythmic micro-gestures as an eyes-free input technique
Reproductive biology of carpenter seabream (Argyrozona argyrozona) (Pisces: Sparidae) in a marine protected area
The carpenter seabream (Argyrozona argyrozona) is an
endemic South African sparid that comprises an important part of the handline fishery. A three-year study (1998â2000) into its reproductive biology within the Tsitsikamma National Park revealed that these fishes are
serial spawning late gonochorists. The size at 50% maturity (L50) was estimated at 292 and 297 mm FL for both females and males, respectively. A likelihood ratio test revealed that there was no significant difference between male and female L50 (P>0.5). Both monthly gonadosomatic indices
and macroscopically determined ovarian stages strongly indicate that A. argyrozona within the Tsitsikamma
National Park spawn in the astral summer between November and April. The presence of postovulatory follicles (POFs) confirmed a six-month spawning season, and monthly proportions of early (0â6 hour old) POFs showed that spawning frequency was highest (once every 1â2 days) from December to March. Although spawning season was more highly correlated to photoperiod (r = 0.859) than temperature
(r = â0.161), the daily proportion of spawning fish was strongly correlated (r= 0.93) to ambient temperature over
the range 9â22oC. These results indicate that short-term upwelling events, a strong feature in the Tsitsikamma
National Park during summer, may negatively affect carpenter fecundity. Both spawning frequency and duration
(i.e., length of spawning season) increased with fish length. As a result of the allometric relationship between
annual fecundity and fish mass a 3-kg fish was calculated to produce fivefold more eggs per kilogram of body weight
than a fish of 1 kg. In addition to producing more eggs per unit of weight each year, larger fish also produce
significantly larger eggs
Recommended from our members
Origin and structure of Devensian depressions at Letton, Herefordshire
Groups of circular to oval enclosed depressions in soft sediments of Pleistocene age are relatively common in north-west Europe. These features are normally interpreted as being either glacial or periglacial in origin. Where these features are developed in glacial sediments, a glacial (and specifically âkettle holeâ) genesis is considered most likely. Some groups of features, however, have been re-interpreted as being periglacial in origin and are thought to be the remains of cryogenic mounds (former pingos or palsas/lithalsas). The problem at many sites, of course, is correct identification and previously this was often resolved through extensive trenching of the sediments. The use of geophysics in the form of electrical resistivity tomography and ground probing radar, however, can aid investigation and interpretation and is less invasive. A group of enclosed depressions in the Letton area of Herefordshire within the Last Glacial Maximum ice limit (Late Devensian) have been investigated in this way. The morphology and internal structure of the features and their existence in glaciolacustrine sediments of Late Devensian age strongly suggests that these depressions are kettle holes resulting from ice block discharge into a shallow lakes or lakes, and hence a glacial origin is supported. The lack of any ramparts surrounding the depressions (at the surface or any evidence of these at depth) and the fact that they do not overlap (âmutually interfereâ) indicates that they are not the remains of cryogenic mounds
Astrometric Detection of Terrestrial Planets in the Habitable Zones of Nearby Stars with SIM PlanetQuest
SIM PlanetQuest (Space Interferometry Mission) is a space-borne Michelson
interferometer for precision stellar astrometry, with a nine meter baseline,
currently slated for launch in 2015. One of the principal science goals is the
astrometric detection and orbit characterization of terrestrial planets in the
habitable zones of nearby stars. Differential astrometry of the target star
against a set of reference stars lying within a degree will allow measurement
of the target star's reflex motion with astrometric accuracy of 1
micro-arcsecond in a single measurement.
We assess SIM's capability for detection (as opposed to characterization by
orbit determination) of terrestrial planets in the habitable zones of nearby
solar-type stars. We compare SIM's performance on target lists optimized for
the SIM and Terrestrial Planet Finder Coronograph (TPF-C) missions. Performance
is quantified by three metrics: minimum detectable planet mass, number and mass
distribution of detected planets, and completeness of detections in each mass
range. Finally, we discuss the issue of confidence in detections and
non-detections, and show how information from SIM's planet survey can enable
TPF to increase its yield of terrestrial planets.Comment: Minor corrections to figures and tables. 46 pages, 27 figures. To
appear in PASP (Publications of the Astronomical Society of the Pacific), May
200
A new methodology for network scale simulation of emerging power line communication standards
This paper presents the development of a new methodology for the simulation of Power Line Communication (PLC) within the popular Electromagnetic Transients Programme-Alternative Transients Programme (EMTP-ATP). As a first application, the comparative performance of the emerging Orthogonal Frequency Division Multiplexing (OFDM) based Prime and G3-PLC narrowband standards is investigated. Models of both standards have been created within the EMTP-ATP and simulations performed using frequency dependent line models and realistic transformer models as terminations. It is observed that both standards are severely affected by the highly frequency selective nature of the MV power line channel and a more considered choice of OFDM parameters may be necessary for optimal performance on MV networks
- âŠ