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Comparable Resolution (comparable + resolution)
Selected AbstractsThe Circumpolar Arctic vegetation mapJOURNAL OF VEGETATION SCIENCE, Issue 3 2005Donald A. Walker Abstract. Question: What are the major vegetation units in the Arctic, what is their composition, and how are they distributed among major bioclimate subzones and countries? Location: The Arctic tundra region, north of the tree line. Methods: A photo-interpretive approach was used to delineate the vegetation onto an Advanced Very High Resolution Radiometer (AVHRR) base image. Mapping experts within nine Arctic regions prepared draft maps using geographic information technology (ArcInfo) of their portion of the Arctic, and these were later synthesized to make the final map. Area analysis of the map was done according to bioclimate subzones, and country. The integrated mapping procedures resulted in other maps of vegetation, topography, soils, landscapes, lake cover, substrate pH, and above-ground biomass. Results: The final map was published at 1:7 500 000 scale map. Within the Arctic (total area = 7.11 × 106 km2), about 5.05 × 106 km2 is vegetated. The remainder is ice covered. The map legend generally portrays the zonal vegetation within each map polygon. About 26% of the vegetated area is erect shrublands, 18% peaty graminoid tundras, 13% mountain complexes, 12% barrens, 11% mineral graminoid tundras, 11% prostrate-shrub tundras, and 7% wetlands. Canada has by far the most terrain in the High Arctic mostly associated with abundant barren types and prostrate dwarf-shrub tundra, whereas Russia has the largest area in the Low Arctic, predominantly low-shrub tundra. Conclusions: The CAVM is the first vegetation map of an entire global biome at a comparable resolution. The consistent treatment of the vegetation across the circumpolar Arctic, abundant ancillary material, and digital database should promote the application to numerous land-use, and climate-change applications and will make updating the map relatively easy. [source] Space very long baseline interferometry observations of polarization in the jet of 3C 380MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 2 2006A. Papageorgiou ABSTRACT A comparison between low-frequency space very long baseline interferometry (VLBI) and high-frequency ground-based VLBI images can, in principle, be used to detect small variations in rotation measure (RM) on fine angular scales inaccessible to ground arrays alone. This paper reports an attempt to perform such a comparison using the jet in the quasar 3C 380. Observations made with the VSOP antenna HALCA together with a ground array at wavelength 1.6 GHz provide total intensity and polarization images of comparable resolution to those from the ground array alone at 5 GHz. The results provide an image showing derotated magnetic vector position angle of somewhat higher resolution than that available earlier. The results show variations in an RM around component A of the order of 10 rad m,2 that could not have been detected with the ground array alone. It is concluded that satellite VLBI observations provide a promising means to study the distribution of matter and magnetic fields around parsec-scale jets. The ground observations used here follow the steady outward drift of component A, which has approximately doubled its distance from the core since the first observations in 1982. They also reveal total intensity and polarization structure associated with a bright knot 0.7 arcsec from the core which is reminiscent of that expected for a conical shock wave. [source] VSOP polarization observations of the BL Lacertae object OJ 287MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 4 2001D. C. Gabuzda VLBI total intensity and linear polarization images of the BL Lacertae object OJ 287 have been obtained at using a global ground array and the HALCA orbiting antenna, and at two weeks earlier using the VLBA. In the ground-based 6-cm images, the source is dominated by a core,jet double structure the components of which are essentially unresolved. The baselines to the orbiting antenna resolve both of these compact components. In the VSOP images, the ground-based ,core' breaks up into several distinct components, demonstrating that this region is dominated by the contribution of bright, optically thin knots of jet emission. A very similar structure is observed in the 1.3-cm image. The magnetic field in the core is transverse, becomes longitudinal in the inner jet, then makes a sharp transition to a region of transverse field further from the core. This suggests that the field in the outer jet has become highly ordered in the transverse direction owing to the action of a shock; the physical nature of the extended region of longitudinal field closer to the core is not clear. The availability of nearly simultaneous observations with comparable resolution at widely spaced frequencies enabled detection of a ,90° rotation in polarization position angle for the core, owing to the transition from the optically thick (6 cm) to the optically thin (1.3 cm) regime. [source] The radio expansion and brightening of the very young supernova remnant G1.9 + 0.3MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY: LETTERS (ELECTRONIC), Issue 1 2008D. A. Green ABSTRACT Recent radio observations of the small Galactic supernova remnant G1.9 + 0.3 made at 4.86 GHz with the Very Large Array are presented, and compared with earlier observations at 1.49 GHz which have a comparable resolution (10 × 4 arcsec2). These show that the radio emission from this remnant has expanded significantly, by about 15 per cent over 23 yr, with a current outer diameter of ,92 arcsec. This expansion confirms that G1.9 + 0.3 is the youngest Galactic remnant yet identified, only about 150 yr old at most. Recent, lower resolution, 1.43-GHz observations are also discussed, and the integrated flux densities from these and the 4.86-GHz observations are compared with earlier results. This shows that the integrated flux density of G1.9 + 0.3 has been increasing recently. [source] A robust cross-linked polyacrylamide coating for microchip electrophoresis of dsDNA fragmentsELECTROPHORESIS, Issue 19 2006Joann J. Lu Abstract Surface derivatization plays an important role in microchip electrophoresis. It not only enhances the resolution, but also improves the reproducibility. So far, the most popularly used derivatization method for glass microchannels is to covalently attach a layer of linear polyacrylamide,(LPA) to the channel surfaces. However, LPA coating has two problems: incomplete coverage and limited lifetime. To address these issues, we have recently developed a cross-linked polyacrylamide,(CPA) derivatization protocol and demonstrated it for high-resolution protein separations by CIEF, CGE, and CZE. In this report, we used this protocol to coat microchip channels and exhibited the reliability and robustness of CPA coating for microchip electrophoresis of DNA molecules. dsDNA fragments were used as our test samples. High resolutions were obtained for fragments ranging from 100,bp to 10,kpb. After more than 800,runs, the CPA-coated microchannels still performed well and comparable resolutions were maintained throughout these runs. [source] | ||||||||||