Synthetic aperture radar (SAR)-based mapping of volcanic flows: Manam Island, Papua New Guinea

International audienceWe present new radar-based techniques for efficient identification of surface changes generated by lava and pyroclastic flows, and apply these to the 1996 eruption of Manam Volcano, Papua New Guinea. Polarimetric L- and P-band airborne synthetic aperture radar (SAR) data, along with a C-band DEM, were acquired over the volcano on 17 November 1996 during a major eruption sequence. The L-band data are analyzed for dominant scattering mechanisms on a per pixel basis using radar target decomposition techniques. A classification method is presented, and when applied to the L-band polarimetry, it readily distinguishes bare surfaces from forest cover over Manam volcano. In particular, the classification scheme identifies a post-1992 lava flow in NE Valley of Manam Island as a mainly bare surface and the underlying 1992 flow units as mainly vegetated surfaces. The Smithsonian's Global Volcanism Network reports allow us to speculate whether the bare surface is a flow dating from October or November in the early part of the late-1996 eruption sequence. This work shows that fully polarimetric SAR is sensitive to scattering mechanism changes caused by volcanic resurfacing processes such as lava and pyroclastic flows. By extension, this technique should also prove useful in mapping debris flows, ash deposits and volcanic landslides associated with major eruptions

Evidence from satellite altimetry for small-scale convection in the mantle

Small scale convection can be defined as that part of the mantle circulation in which upwellings and downwellings can occur beneath the lithosphere within the interiors of plates, in contrast to the large scale flow associated with plate motions where upwellings and downwellings occur at ridges and trenches. The two scales of convection will interact so that the form of the small scale convection will depend on how it arises within the large scale flow. Observations based on GEOS-3 and SEASAT altimetry suggest that small scale convection occurs in at least two different ways

Synthetic aperture radar (SAR)-based mapping of volcanic flows: Manam Island, Papua New Guinea

We present new radar-based techniques for efficient identification of surface changes generated by lava and pyroclastic flows, and apply these to the 1996 eruption of Manam Volcano, Papua New Guinea. Polarimetric L- and P-band airborne synthetic aperture radar (SAR) data, along with a C-band DEM, were acquired over the volcano on 17 November 1996 during a major eruption sequence. The L-band data are analyzed for dominant scattering mechanisms on a per pixel basis using radar target decomposition techniques. A classification method is presented, and when applied to the L-band polarimetry, it readily distinguishes bare surfaces from forest cover over Manam volcano. In particular, the classification scheme identifies a post-1992 lava flow in NE Valley of Manam Island as a mainly bare surface and the underlying 1992 flow units as mainly vegetated surfaces. The Smithsonian's Global Volcanism Network reports allow us to speculate whether the bare surface is a flow dating from October or November in the early part of the late-1996 eruption sequence. This work shows that fully polarimetric SAR is sensitive to scattering mechanism changes caused by volcanic resurfacing processes such as lava and pyroclastic flows. By extension, this technique should also prove useful in mapping debris flows, ash deposits and volcanic landslides associated with major eruptions

La gran espuma: arqueología industrial y arquitectura fabril cervecera en Buenos Aires

Desde la revolución industrial del siglo XVIII se instala la vida en las fábricas. Su diseño para albergar los procesos de producción integra hoy el paisaje de todas las grandes ciudades del mundo. Industrias y fábricas: los espacios de producción variaron a través del tiempo. Denotan el crecimiento de mercados de consumo; y reflejan la inversión de capitales y dinámicas productivas industriales a escala global. A lo largo de la historia, las crisis económicas y los contextos políticos afectaron su perdurabilidad, produciendo un registro de alta variabilidad. En este trabajo exploramos la historia del diseño, uso y transformación de los espacios de producción en Buenos Aires. Para tal efecto buscamos caracterizar la composición, diversidad, persistencia y variabilidad de la planta industrial cervecera durante los siglos XIX y XX. Mediante el análisis de fuentes primarias y secundarias se plantea una investigación teórico-metodológica elaborando datos cuantitativos y cualitativos.Life in factories starts with eighteen's century industrial revolution. Today, their designed forms, built to accommodate the production processes could be found in every big city in the world. They denote consumer market growth and global scale industrial production dynamics. Through history, economic crisis and political contexts affected the production’s spaces perdurability, hence producing a record of high variability. In this paper we go through design history, use and transformation of Buenos Aires production spaces. In order to so, we look forward to characterize spatial composition, diversity, persistence and variability of beer industrial settlement during XlXth and XXth centuries. Using the analysis of primary and secondary sources we propose a theoretical and methodological research, handling quantitative and qualitative data.Facultad de Arquitectura y Urbanism

La gran espuma: arqueología industrial y arquitectura fabril cervecera en Buenos Aires

Desde la revolución industrial del siglo XVIII se instala la vida en las fábricas. Su diseño para albergar los procesos de producción integra hoy el paisaje de todas las grandes ciudades del mundo. Industrias y fábricas: los espacios de producción variaron a través del tiempo. Denotan el crecimiento de mercados de consumo; y reflejan la inversión de capitales y dinámicas productivas industriales a escala global. A lo largo de la historia, las crisis económicas y los contextos políticos afectaron su perdurabilidad, produciendo un registro de alta variabilidad. En este trabajo exploramos la historia del diseño, uso y transformación de los espacios de producción en Buenos Aires. Para tal efecto buscamos caracterizar la composición, diversidad, persistencia y variabilidad de la planta industrial cervecera durante los siglos XIX y XX. Mediante el análisis de fuentes primarias y secundarias se plantea una investigación teórico-metodológica elaborando datos cuantitativos y cualitativos.Life in factories starts with eighteen's century industrial revolution. Today, their designed forms, built to accommodate the production processes could be found in every big city in the world. They denote consumer market growth and global scale industrial production dynamics. Through history, economic crisis and political contexts affected the production’s spaces perdurability, hence producing a record of high variability. In this paper we go through design history, use and transformation of Buenos Aires production spaces. In order to so, we look forward to characterize spatial composition, diversity, persistence and variability of beer industrial settlement during XlXth and XXth centuries. Using the analysis of primary and secondary sources we propose a theoretical and methodological research, handling quantitative and qualitative data.Facultad de Arquitectura y Urbanism

Sr-Nd-Pb-Hf isotope results from ODP Leg 187: Evidence for mantle dynamics of the Australian-Antarctic Discordance and origin of the Indian MORB source

New high precision PIMMS Hf and Pb isotope data for 14–28 Ma basalts recovered during ODP Leg 187 are compared with zero-age dredge samples from the Australian-Antarctic Discordance (AAD). These new data show that combined Nd-Hf isotope systematics can be used as an effective discriminant between Indian and Pacific MORB source mantle domains. In particular, Indian mantle is displaced to lower εNd and higher εHf ratios compared to Pacific mantle. As with Pb isotope plots, there is almost no overlap between the two mantle types in Nd-Hf isotope space. On the basis of our new Nd-Hf isotope data, we demonstrate that Pacific MORB-source mantle was present near the eastern margin of the AAD from as early as 28 Ma, its boundary with Indian MORB-source mantle coinciding with the eastern edge of a basin-wide arcuate depth anomaly that is centered on the AAD. This observation rules out models requiring rapid migration of Pacific MORB mantle into the Indian Ocean basin since separation of Australia from Antarctica. Although temporal variations in isotopic composition can be discerned relative to the fracture zone boundary of the modern AAD at 127°E, the distribution of different compositional groups appears to have remained much the same relative to the position of the residual depth anomaly for the past 30 m.y. Thus significant lateral flow of mantle along the ridge axis toward the interface appears unlikely. Instead, the dynamics that maintain both the residual depth anomaly and the isotopic boundary between Indian and Pacific mantle are due to eastward migration of the Australian and Antarctic plates over a stagnated, but slowly upwelling, slab oriented roughly orthogonal to the ridge axis. Temporal and spatial variations in the compositions of Indian MORB basalts within the AAD can be explained by progressive displacement of shallower Indian MORB-source mantle by deeper mantle having a higher εHf composition ascending ahead of the upwelling slab. Models for the origin of the distinctive composition of the Indian MORB-source based on recycling of a heterogeneous enriched component that consist of ancient altered ocean crust plus<10% pelagic sediment are inconsistent with Nd-Hf isotope systematics. Instead, the data can be explained by a model in which Indian mantle includes a significant proportion of material that was processed in the mantle wedge above a subduction zone and was subsequently mixed back into unprocessed upper mantle

Origin of the Louisville ridge and its relationship to the Eltanin Fracture Zone System

We have combined shipboard and Seasat altimeter derived data in an intergrated geological and geophysical study of the Louisville Ridge; a 3500-km-long seamount chain extending from the Tonga trench to the Eltanin Fracture Zone. A break in the smooth trend of the ridge at latitude 37.5°S has been recognized in both bathymetric and altimetric data. The ⁴⁰Ar-³⁹Ar dating of rocks dredged either side of the break suggest that it is analogous to the bend in the Hawaiian-Emperor seamount chain. Although the general trend of the ridge can be fit by small circles about Pacific absolute motion poles determined from other seamount chains, the new bathymetric and age data allow us to refine Pacific absolute motion poles. The continuity in smooth trend of the ridge and the Eltanin Fracture Zone suggests some relationship between them. However, a major offset developed on this transform between 60 and 80 Ma, prior to the oldest dated rocks from the ridge. Although magmatism was more or less continuous on the ridge during 28-60 Ma, it probably occurred on crust with little or no offset. Thus magmatism appears to have been little influenced by the developing fracture zone. 8y 28 Ma, the distance between the magmatic source and the fracture zone had decreased sufficiently for a portion of the ridge to have been emplaced on crust with an offset. After about 12 Ma, however, volcanic activity on the Louisville Ridge apparently waned, despite a possible influence on the magmatism of the fracture zone.Copyrighted by American Geophysical Union

Balancing Power Consumption in Multiprocessor Systems

Actions usually taken to prevent processors from overheating, such as decreasing the frequency or stopping the execution flow, also degrade performance. Multiprocessor systems, however, offer the possibility of moving the task that caused a CPU to overheat away to some other, cooler CPU, so throttling becomes only a last resort taken if all of a system\u27s processors are hot. Additionally, the scheduler can take advantage of the energy characteristics of individual tasks, and distribute hot tasks as well as cool tasks evenly among all CPUs. This work presents a mechanism for determining the energy characteristics of tasks by means of event monitoring counters, and an energy-aware scheduling policy that strives to assign tasks to CPUs in a way that avoids overheating individual CPUs. Our evaluations show that the benefit of avoiding throttling outweighs the overhead of additional task migrations, and that energy-aware scheduling in many cases increases the system\u27s throughput