20,570 research outputs found
Glacier motion estimation using SAR offset-tracking procedures
Two image-to-image patch offset techniques for
estimating feature motion between satellite synthetic aperture radar (SAR) images are discussed. Intensity tracking, based on patch intensity cross-correlation optimization, and coherence tracking, based on patch coherence optimization, are used to estimate the movement of glacier surfaces between two SAR images in both slant-range and azimuth direction. The accuracy and application range of the two methods are examined in the case of the surge of Monacobreen in Northern Svalbard between
1992 and 1996. Offset-tracking procedures of SAR images are an alternative to differential SAR interferometry for the estimation of glacier motion when differential SAR interferometry is limited by loss of coherence, i.e., in the case of rapid and incoherent flow and of large acquisition time intervals between the two SAR images. In addition, an offset-tracking procedure in the azimuth
direction may be combined with differential SAR interferometry in the slant-range direction in order to retrieve a two-dimensional displacement map when SAR data of only one orbit configuration are available
Impact assessment of rehabilitation intervention in the Gal Oya Left Bank [Sri Lanka].
Irrigation managementWater managementIrrigation systemsProductivityRehabilitationModelsProject evaluationRainReservoir storage
Human gustation: when the brain has taste.
What we put into our mouths can nourish or kill us. A new study uses state-of-the-art electroencephalogram decoding to detail how we and our brains know what we taste
The effect of small elongations on the electronic and optical signatures in InAs nanocrystal quantum dots
We present a detailed theoretical investigation of the electronic structure and
optical properties of InAs nanocrystals at the transition from spheres to rods. Using
a semiempirical pseudopotential approach, we predict that, despite the qualitative
similarity of both intra- and inter-band optical spectra, for NCs with R > 15 °A even
slight elongations should result in shifts of the order of hundreds of meV in the spacings
between STM peaks measured in the positive bias regime, in the position of the intra-
band absorption peaks associated with transitions in the conduction band and in the
separation between the first and the fifth peak in PLE experiments. Our results show
that, based on the spectroscopic data, it should be possible to discriminate between
spherical and elongated NCs with aspect ratios of length over diameter as small as
1.2. Indeed our results suggest that many nominally spherical experimental samples
contained a large fraction of slightly elongated structures
Discovery of disc precession in the M31 dipping X-ray binary Bo 158
We present results from three XMM-Newton observations of the M31 low mass
X-ray binary XMMU J004314.4+410726.3 (Bo 158), spaced over 3 days in 2004,
July. Bo 158 was the first dipping LMXB to be discovered in M31. Periodic
intensity dips were previously seen to occur on a 2.78-hr period, due to
absorption in material that is raised out of the plane of the accretion disc.
The report of these observations stated that the dip depth was anti-correlated
with source intensity. However, our new observations do not favour a strict
intensity dependance, but rather suggest that the dip variation is due to
precession of the accretion disc. This is to be expected in LMXBs with a mass
ratio <~ 0.3 (period <~ 4 hr), as the disc reaches the 3:1 resonance with the
binary companion, causing elongation and precession of the disc. A smoothed
particle hydrodynamics simulation of the disc in this system shows retrograde
rotation of a disc warp on a period of ~11 P_orb, and prograde disc precession
on a period of ~29 P_orb. This is consistent with the observed variation in the
depth of the dips. We find that the dipping behaviour is most likely to be
modified by the disc precession, hence we predict that the dipping behaviour
repeats on a 81+/-3 hr cycle.Comment: 9 pages, 6 figures, accepted for publication by MNRAS, changed
conten
Spatial organization and evolutional period of the epidemic model using cellular automata
We investigate epidemic models with spatial structure based on the cellular
automata method. The construction of the cellular automata is from the study by
Weimar and Boon about the reaction-diffusion equations [Phys. Rev. E 49, 1749
(1994)]. Our results show that the spatial epidemic models exhibit the
spontaneous formation of irregular spiral waves at large scales within the
domain of chaos. Moreover, the irregular spiral waves grow stably. The system
also shows a spatial period-2 structure at one dimension outside the domain of
chaos. It is interesting that the spatial period-2 structure will break and
transform into a spatial synchronous configuration in the domain of chaos. Our
results confirm that populations embed and disperse more stably in space than
they do in nonspatial counterparts.Comment: 6 papges,5 figures. published in Physics Review
Does my brain want what my eyes like? - How food liking and choice influence spatio-temporal brain dynamics of food viewing.
How food valuation and decision-making influence the perception of food is of major interest to better understand food intake behavior and, by extension, body weight management. Our study investigated behavioral responses and spatio-temporal brain dynamics by means of visual evoked potentials (VEPs) in twenty-two normal-weight participants when viewing pairs of food photographs. Participants rated how much they liked each food item (valuation) and subsequently chose between the two alternative food images. Unsurprisingly, strongly liked foods were also chosen most often. Foods were rated faster as strongly liked than as mildly liked or disliked irrespective of whether they were subsequently chosen over an alternative. Moreover, strongly liked foods were subsequently also chosen faster than the less liked alternatives. Response times during valuation and choice were positively correlated, but only when foods were liked; the faster participants rated foods as strongly liked, the faster they were in choosing the food item over an alternative. VEP modulations by the level of liking attributed as well as the subsequent choice were found as early as 135-180ms after food image onset. Analyses of neural source activity patterns over this time interval revealed an interaction between liking and the subsequent choice within the insula, dorsal frontal and superior parietal regions. The neural responses to food viewing were found to be modulated by the attributed level of liking only when foods were chosen, not when they were dismissed for an alternative. Therein, the responses to disliked foods were generally greater than those to foods that were liked more. Moreover, the responses to disliked but chosen foods were greater than responses to disliked foods which were subsequently dismissed for an alternative offer. Our findings show that the spatio-temporal brain dynamics to food viewing are immediately influenced both by how much foods are liked and by choices taken on them. These valuation and choice processes are subserved by brain regions involved in salience and reward attribution as well as in decision-making processes, which are likely to influence prospective dietary choices in everyday life
Population dynamics at high Reynolds number
We study the statistical properties of population dynamics evolving in a
realistic two-dimensional compressible turbulent velocity field. We show that
the interplay between turbulent dynamics and population growth and saturation
leads to quasi-localization and a remarkable reduction in the carrying
capacity. The statistical properties of the population density are investigated
and quantified via multifractal scaling analysis. We also investigate
numerically the singular limit of negligibly small growth rates and
delocalization of population ridges triggered by uniform advection.Comment: 5 pages, 5 figure
- …