98 research outputs found
Internet as an Instrument to Transmit Theoretical Knowledge
The problem of transmitting theoretical knowledge and the role of the Internet in it require the solution due to the existing modernization of theoretical knowledge transmission process. The objective of this research is to define the role of the Internet in transmitting theoretical knowledge as it is the extremely important resource of the modern society. According to the carried out analysis of the problem and its solution the information technology is not only the mean that accumulates the volumes of knowledge, but also the tool of its social use, forms of social activity by way of social and information technology. As a result, using method of the methodological analysis in combination with competency-based approach we revealed that the Internet as a diachronic way of transmitting knowledge and experience is characterized by a polyagentity and interdisciplinarity
Comment mesurer les progrĂšs de la lecture?
New observations of Neptuneâs clouds in the near infrared were acquired in October 2013 with SINFONI on ESOâs Very Large Telescope (VLT) in Chile. SINFONI is an Integral Field Unit spectrometer returning a 64 Ă 64 pixel image with 2048 wavelengths. Image cubes in the J-band (1.09 â 1.41 ÎŒm) and H-band (1.43 â 1.87 ÎŒm) were obtained at spatial resolutions of 0.1âłand 0.025âłper pixel, while SINFONIâs adaptive optics provided an effective resolution of approximately 0.1âł. Image cubes were obtained at the start and end of three successive nights to monitor the temporal development of discrete clouds both at short timescales (i.e. during a single night) as well as over the longer period of the three-day observing run. These observations were compared with similar H-band observations obtained in September 2009 with the NIFS Integral Field Unit spectrometer on the Gemini-North telescope in Hawaii, previously reported by Irwin et al., Icarus 216, 141-158, 2011, and previously unreported Gemini/NIFS observations at lower spatial resolution made in 2011.
We find both similarities and differences between these observations, spaced over four years. The same overall cloud structure is seen with high, bright clouds visible at mid-latitudes (30 â 40°N,S), with slightly lower clouds observed at lower latitudes, together with small discrete clouds seen circling the pole at a latitude of approximately 60°S. However, while discrete clouds were visible at this latitude at both the main cloud deck level (at 2â3 bars) and in the upper troposphere (100â500mb) in 2009, no distinct deep (2â3 bar), discrete circumpolar clouds were visible in 2013, although some deep clouds were seen at the southern edge of the main cloud belt at 30â40°S, which have not been observed before. The nature of the deep sub-polar discrete clouds observed in 2009 is intriguing. While it is possible that in 2013 these deeper clouds were masked by faster moving, overlying features, we consider that it is unlikely that this should have happened in 2013, but not in 2009 when the upper-cloud activity was generally similar. Meanwhile, the deep clouds seen at the southern edge of the main cloud belt at 30 â 40°S in 2013, should also have been detectable in 2009, but were not seen. Hence, these observations may have detected a real temporal variation in the occurrence of Neptuneâs deep clouds, pointing to underlying variability in the convective activity at the pressure of the main cloud deck at 2â3 bars near Neptuneâs south pole and also in the main observable cloud belt at 30 â 40°S.</p
HCN ice in Titan's high-altitude southern polar cloud
Titan's middle atmosphere is currently experiencing a rapid change of season
after northern spring arrived in 2009. A large cloud was observed for the first
time above Titan's southern pole in May 2012, at an altitude of 300 km. This
altitude previously showed a temperature maximum and condensation was not
expected for any of Titan's atmospheric gases. Here we show that this cloud is
composed of micron-sized hydrogen cyanide (HCN) ice particles. The presence of
HCN particles at this altitude, together with new temperature determinations
from mid-infrared observations, indicate a very dramatic cooling of Titan's
atmosphere inside the winter polar vortex in early 2012. Such a cooling is
completely contrary to previously measured high-altitude warming in the polar
vortex, and temperatures are a hundred degrees colder than predicted by
circulation models. Besides elucidating the nature of Titan's mysterious polar
cloud, these results thus show that post-equinox cooling at the winter pole is
much more efficient than previously thought.Comment: Published in Nature on 2 October 2014. This is the author version,
before final editing by Natur
Listening for the landing: seismic detections of perseverance's arrival at Mars with InSight
The entry, descent, and landing (EDL) sequence of NASA's Mars 2020 Perseverance Rover will act as a seismic source of known temporal and spatial localization. We evaluate whether the signals produced by this event will be detectable by the InSight lander (3,452 km away), comparing expected signal amplitudes to noise levels at the instrument. Modeling is undertaken to predict the propagation of the acoustic signal (purely in the atmosphere), the seismoacoustic signal (atmosphere-to-ground coupled), and the elastodynamic seismic signal (in the ground only). Our results suggest that the acoustic and seismoacoustic signals, produced by the atmospheric shock wave from the EDL, are unlikely to be detectable due to the pattern of winds in the martian atmosphere and the weak air-to-ground coupling, respectively. However, the elastodynamic seismic signal produced by the impact of the spacecraft's cruise balance masses on the surface may be detected by InSight. The upper and lower bounds on predicted ground velocity at InSight are 2.0 Ă 10â14 and 1.3 Ă 10â10 m sâ1. The upper value is above the noise floor at the time of landing 40% of the time on average. The large range of possible values reflects uncertainties in the current understanding of impact-generated seismic waves and their subsequent propagation and attenuation through Mars. Uncertainty in the detectability also stems from the indeterminate instrument noise level at the time of this future event. A positive detection would be of enormous value in constraining the seismic properties of Mars, and in improving our understanding of impact-generated seismic waves
Largest recent impact craters on Mars: Orbital imaging and surface seismic co-investigation.
Two >130-meter-diameter impact craters formed on Mars during the later half of 2021. These are the two largest fresh impact craters discovered by the Mars Reconnaissance Orbiter since operations started 16 years ago. The impacts created two of the largest seismic events (magnitudes greater than 4) recorded by InSight during its 3-year mission. The combination of orbital imagery and seismic ground motion enables the investigation of subsurface and atmospheric energy partitioning of the impact process on a planet with a thin atmosphere and the first direct test of martian deep-interior seismic models with known event distances. The impact at 35°N excavated blocks of water ice, which is the lowest latitude at which ice has been directly observed on Mars
Quantifying the effect of finite field-of-view size on radiative transfer calculations of Titan's limb spectra measured by Cassini-CIRS
The Composite InfraRed Spectrometer (CIRS) on-board the Cassini spacecraft has currently returned around three years worth of data from Saturn's largest moon Titan. One of the unique aspects of CIRS is to take high spatial resolution spectra of the limb of Titan, with sub-scale height (20-40 km) resolutions. This is made possible by the small field-of-view (FOV) of the mid-IR detectors. However, many limb spectra have moderate to large sized FOVs, which introduces bias into retrieved profiles of temperature and abundance unless the finite FOV size is taken into account. The bias can be reduced by calculating a FOV-averaged spectrum comprising a weighted sum of a small number of spectra with infinitesimal FOVs across the FOV. Here we introduce a scheme for incorporating FOV averaging into radiative transfer calculations of CIRS spectra and quantify the errors as a function of number of FOV averaging points, FOV size, tangent altitude, and wavenumber. The optimum number of FOV averaging points for a given observation can then be found by matching the calculated FOV averaging error with the measurement error. This allows for accurate analysis of a vast amount of Cassini-CIRS data. © 2007 Springer Science+Business Media B.V
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