LRS Bianchi type-I models with constant deceleration parameter in?creation field cosmology

We have studied Locally Rotationally Symmetric (LRS) Bianchi type-I space-time having constant deceleration parameter and filled with perfect fluid in the Hoyle-Narlikar C-field cosmology. Here, the creation field C is a function of time t only. The geometrical and physical aspects for the models are also studied.     

An in situ investigation of the preservation and alteration of presolar silicates in the Miller Range 07687 chondrite

Dust grains that formed around ancient stars and in stellar explosions seeded the early solar protoplanetary disk. While most of such presolar grains were destroyed during solar system formation, a fraction of such grains were preserved in primitive materials such as meteorites. These grains can provide constraints on stellar origins and secondary processing such as aqueous alteration and thermal metamorphism on their parent asteroids. Here, we report on the nature of aqueous alteration in the Miller Range (MIL) 07687 chondrite through the analysis of four presolar silicates and their surrounding material. The grains occur in the Fe-rich and Fe-poor lithologies, reflecting relatively altered and unaltered material, respectively. The O-isotopic compositions of two grains, one each from the Fe-rich and Fe-poor matrix, are consistent with formation in the circumstellar envelopes of low-mass Asymptotic Giant Branch (AGB)/Red Giant Branch (RGB) stars. The other two grains, also one each from the Fe-rich and Fe-poor matrix, have O-isotopic compositions consistent with formation in the ejecta of type-II supernovae (SNe). The grains derived from AGB/RGB stars include two polycrystalline pyroxene grains that contain Fe-rich rims. The SNe grains include a polycrystalline Ca-bearing pyroxene and a polycrystalline assemblage consistent with a mixture of olivine and pyroxene. Ferrihydrite is observed in all focused ion beam sections, consistent with parent-body aqueous alteration of the fine-grained matrix under oxidizing conditions. The Fe-rich rims around presolar silicates in this study are consistent with Fe-diffusion into the grains resulting from early-stage hydrothermal alteration, but such alteration was not extensive enough to lead to isotopic equilibration with the surrounding matrix.     

PROBLEMS IN CONSTRUCTING A BATHYMETRIC BASE MAP FOR THE GULF OF FINLAND

The various steps required for compilation of a bathymetric chart of the Gulf of Finland are outlined, taking into account the specific conditions characteristic of that water body. The use of available initial source materials and special survey work required for supplementing these sources is discussed. Translated by Edward Torrey, Alexandria, VA 22308 from: Geodeziya i kartografiya, 1988, No. 8, pp. 40-42.     

The interpretation of body trace metal concentrations in neogastropods from Hong Kong.

Three species of neogastropods, i.e., Thais clavigera, Thais luteostoma and Morula musiva, were collected from 12 sites in the coastal waters of Hong Kong, including clean and known metal-enriched ones. Accordingly, body trace metal concentrations varied greatly. Copper and zinc body concentrations compared poorly with those of accepted biomonitors and presumed metal contamination profiles. Much is known about the feeding ecology of neogastropods on local shores and where direct observational data were not available, their diets could, nevertheless, be estimated reliably. Accumulated metal concentrations can be interpreted with regard to dietary history. T. luteostoma, for example, had body copper concentrations of 51.8 microg g(-1) on an exposed shore and a diet of mainly barnacles. In contrast, on a sheltered shore (but only some 250 m distant) where the diet consisted mainly of oysters, body copper concentrations were approximately 15 times greater at 833 microg g(-1). Similar results were obtained for T. clavigera. The results of this analysis suggest that neogastropods can play a significant role in trace metal trophic transfer studies, especially as their representatives are intertidally and subtidally ubiquitous and can be spatially separated into tropical specialists and temperate generalists.     

Petrographic and trace-element distribution studies on the dolomite-calcite in the regional metamorphic marble of the Griesscharte,Tyrol, Austria/Italy

Petrographic investigations on the light yellow marble outcrops in the Griesscharte, Tyrol, Austria/Italy revealed them to be dolomite. The white to blue-grey veins in these marbles were those of calcite. Inside these calcites and along the calcite-dolomite phase boundaries minute and microscopically unidentifiable crystallites (? 10 μ) were observed. These crystallites were recognised by X-ray diffractometry as dolomite and their form and distribution were established by scanning electron microscopy. Trace-element distributions on the calcite-dolomite neighbours were studied by neutron-activation method to elucidate the formation mechanism of these calcites in the marble.Genetic relationships of the dolomite crystallites, the calcite host and the surrounding dolomite marble have been discussed in the light of the petrographic and chemical studies. These findings substantiate a deposition of a new formed vein of calcite from the solution circulating in the fissures of the dolomite marble during prograde metamorphism rather than a simple deposition of mobilized sedimentary calcite. The dolomite crystallites in the calcite seem to have been formed post-tectonically, partly by the nucleation in the calcite cleavage planes during Mg-metasomatism and partly from the exsolutions during retrograde metamorphism.     

Modelling the bar in the centre of the starburst galaxy M82

We present VLA A-array 21-cm atomic hydrogen (H  i ) absorption observed against the central region of the starburst galaxy M82 with an angular resolution of ∼1.3 arcsec (≃20 pc). These observations, together with MERLIN H  i absorption measurements, are compared with the molecular (CO) and ionized ([Ne  ii ]) gas distributions and are used to constrain the dynamics and structure of the ionized, neutral and molecular gas in this starburst.
A position–velocity diagram of the H  i distribution reveals an unusual 'hole' feature which, when previously observed in CO, has been interpreted as an expanding superbubble contained within a ring of gas in solid body rotation. However, we interpret this feature as a signature of a nearly edge-on barred galaxy. In addition, we note that the CO, H  i and [Ne  ii ] position–velocity diagrams reveal two main velocity gradients, and we interpret these as gas moving on x₁- and x₂-orbits within a bar potential. We find the best fit to the data to be produced using a bar potential with a flat rotation curve velocity v _b=140 km s⁻¹ and a total length of 1 kpc, a non-axisymmetry parameter q =0.9, an angular velocity of the bar Ω_b=217 km s⁻¹ arcsec⁻¹, a core radius R _c=25 pc, an inclination angle i =80° and a projected angle between the bar and the major axis of the galaxy φ '=4°. We also discuss the orientation of the disc and bar in M82.     

Bistatic Radar Detection in the Luna-Resurs Mission

An overview of radiophysical investigations of the lunar soil and plasma shell by active radar detection with the use of spacecraft is presented. The possibility is analyzed of conducting bistatic measurements using the Irkutsk Incoherent Scattering Radar and the onboard radar system RLK-L which is being developed for the orbital station of the Luna-Resurs mission.     

Closing down bars in the inner city centre: Informal urban planning,civil insecurity and subjectivity in Bolivia

The paper presents an ethnographic analysis of a group of secondary school students' protests against (illegal) bars in the city centre of El Alto, Bolivia. It shows how informal and formal practices are entangled through the state's dependence on the (illegal) actions of the citizenry in order to ensure civil security. The paper suggests that urban intervention is coproduced by state and nonstate actors at the margins of the state and that urban transformation entails subject formation, in this case that of political youth. Following Hansen and Verkaaik's (2009) argument that the city is essentially multilayered and unknowable, I argue that urban life, as well as state‐citizen relations, is indeterminate, and that it is due to this indeterminacy that the students succeeded in transforming a common association between Alteño youth, alcohol consumption and potential criminal conduct into an alternative notion of youth as responsible citizens of the New Bolivia. This conceptualization permits us to understand the urban sphere as a space not only of conflict but also of endurance and hope, and hence as a zone that allows for the imaginative production of the otherwise (Povinelli, 2011).     

Landscape Controls on Structural Variation in Eucalypt Vegetation Communities: Woronora Plateau,Australia

Quantification of landscape-based vegetation structural variation and pattern is a significant goal for a variety of ecological, monitoring and biodiversity studies. Vegetation structural metrics, derived from airborne laser scanning (ALS or aerial light detection and ranging—LiDAR) and QuickBird satellite imagery, were used to establish the degree of plot-based vegetation variation at a hillslope scale. Topographic position is an indicator of energy and water availability, and was quantified using DEM-based insolation and topographic wetness, respectively, stratifying areas into hot-warm-cold and wet-moist-dry topographic classes. A range of vegetation metrics—maximum and modal canopy height, crown cover, foliage cover, NDVI and semivariance—were compared among randomly selected plots from each topographic class. NDVI increases with increasing landscape wetness, whereas ALS-derived foliage cover decreases with increasing insolation. Foliage cover is well correlated with crown cover (R ² =0.65), and since foliage cover is readily calculable for whole-of-landscape application, it will provide valuable and complementary information to NDVI. Between-plot heterogeneity increases with increasing wetness and decreasing insolation, indicating that more sampling is required in these locations to capture the full range of landscape-based variability. Pattern analysis in landscape ecology is one of the fundamental requirements of landscape ecology, and the methods described here offer statistically significant, quantifiable and repeatable means to realise that goal at a fine spatial grain.     

Longitudinal dispersion compensation for the Very Large Telescope Interferometer

The Very Large Telescope Interferometer [1,13] will be operated in air which will introduce small optical path fluctuations due to internal turbulence [4,6] and dispersion effects. Both may contribute to fringe contrast decrease. Longitudinal dispersion effects can be corrected by inserting an appropriate glass of variable thickness in one arm of the interferometer [3,5,11,12]. This paper presents a new method applied to VLTI in order to select the optimum glass, according to both the observing wavelength and the spectral bandpath, and to calculate its thickness. Results are presented in terms of improvement on the fringe contrast.