Reionization and the Cosmic Dawn with the Square Kilometre Array

The Square Kilometre Array (SKA) will have a low frequency component (SKA-low) which has as one of its main science goals the study of the redshifted 21 cm line from the earliest phases of star and galaxy formation in the Universe. This 21 cm signal provides a new and unique window both on the time of the formation of the first stars and accreting black holes and the subsequent period of substantial ionization of the intergalactic medium. The signal will teach us fundamental new things about the earliest phases of structure formation, cosmology and even has the potential to lead to the discovery of new physical phenomena. Here we present a white paper with an overview of the science questions that SKA-low can address, how we plan to tackle these questions and what this implies for the basic design of the telescope.     

Considerazioni intorno ad alcuni metodi per il calcolo delle riduzioni topografiche nei rilievi eötvössiani

Riassunto L'Autore in questa Nota confronta un procedimento grafico, proposto ed illustrato in precedenti ricerche, con le formole delloSchweydar che sono senza dubbio le più adoperate attualmente nella valutazione delle correzioni topografiche da apportare agli elementi rilevati con la bilancia di torsione, e richiama, fra l'altro, l'attenzione sulle condizioni di applicabilità degli sviluppi e sull'espressione generale dei coefficienti che entrano nella formazione di questi. Completano il lavoro alcune relazioni per il controllo del calcolo dei coefficienti.

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Zusammenfassung Der Verf. vergleicht ein graphisches Verfahren, welches von ihm in früheren Untersuchungen angegeben und erläutert worden ist, mit den Formeln vonSchweydar, welche zweifellos in der Berechnung der topographischen Korrektionen der Grössen die mit der Drehwaage gemessen werden die mehr gebrauchten sind. Ausserdem, gibt er die Anwendungsbedingungen für die Entwicklungen und über den allgemeinen Ausdruck der Koeffizienten welche in der Bildung jener Entwicklungen auftreten. Zuletzt, ist die Arbeit mit einigen Verbindungen zur Kontrolle der Berechnung der Koeffizienten ergänzt.

     

Modeling spatial landslide susceptibility in volcanic terrains through continuous neighborhood spatial analysis and multiple logistic regression in La Ciénega watershed,Nevado de Toluca,Mexico

Natural Hazards - Little study has been done on the effect of the pixel neighborhood information when modeling landslide susceptibility using multiple logistic regression (MLR). The present...     

Mineral-Potential Mapping for MVT Deposits with Limited Data Sets Using Landsat Data and Geological Evidence in the Borden Basin, Northern Baffin Island, Nunavut, Canada

Posterior probabilities of occurrence for Zn-Pb Mississippi Valley Type (MVT) mineralization were calculated based on evidence maps derived from regional geology, Landsat-TM, RADARSAT-1, a digital elevation model and aeromagnetic data sets in the Borden Basin of northern Baffin Island, Canada. The vector representation of geological contacts and fault traces were refined according to their characteristics identified in Landsat-TM, RADARSAT-1, DEM, slope, aspect, and shaded relief data layers. Within the study area, there is an association between the occurrence of MVT mineralization and proximity to the contact of platformal carbonates and shale units of the adjacent geological formation. A spatial association also tends to exist between mineralization and proximity to E-W and NW-SE trending faults. The relationships of known MVT occurrences with the geological features were investigated by spatial statistical techniques to generate evidence maps. Supervised classification and filtering were applied to Landsat-TM data to divide the Society Cliffs Formation into major stratigraphic subunits. Because iron oxides have been observed at some of the MVT occurrences within the Borden Basin, Landsat-TM data band ratio (3/1) was calculated to highlight the potential presence of iron-oxides as another evidence map. Processed Landsat-TM data and other derived geological evidence maps provided useful indicators for identifying areas of potential MVT mineralization. Weights of evidence and logistic regression were used independently to integrate and generate posterior probability maps showing areas of potential mineralization based on all derived evidence maps. Results indicate that in spite of the lack of important data sets such as stream or lake sediment geochemistry, Landsat-TM data and regional geological data can be useful for MVT mineral-potential mapping.     

Cities on edge: Smuggling and neoliberal policies at the Iguazú triangle

The vision of a borderless world, of people, ideas and products freely circulating within a self‐regulating market, is one that clashes with the emerging legal regime based on the punitive force of the state. After a period of liberalization, seen in the opening of national economies and the promotion of regional trade projects and free‐trade zones, the ambivalence of neoliberalism is manifest in a borderless capitalism that ambiguously depends on the securitization of national borders. Such a changing regime of state intervention is clearly seen at the Iguazú triangle – the tri‐border urban conglomerate that straddles Brazil, Paraguay and Argentina – where the illegality of informal cross‐border trading has been tolerated for decades. Recently stepped up police raids and controls hinder the passage of people and goods, while a new fiscal regime introduced in 2009 in Brazil attempts to regularize cross‐border trafficking by turning petty smugglers into micro entrepreneurs. Petty smugglers – dubbed sacoleiros– can hardly be defined as entrepreneurs and do not constitute an identifiable category of entrepreneurship but, as typical in the informal sector, act on opportunity and need. Drawing on ethnographic research, this paper contextualizes the programmes for border controls and regularizing smuggling inspired by neoliberal ideology in South America.     

The Qijurittuq site (IbGk-3), Eastern Hudson Bay: An IPY Interdisciplinary Study

Geografisk Tidsskrift—Danish Journal of Geography 110(2):227–243, 2010

An interdisciplinary study was conducted at Qijurittuq (IbGk-3), an archaeological site located on Drayton Island along the eastern shore of Hudson Bay, Nunavik. Local Inuit made important contributions to the research. High school students participated in the field school, and elders shared their traditional knowledge. The elders expressed an interest in the source of the wood used to construct Qijurittuq's semi-subterranean dwellings, and this inspired us to expand our research in that direction. This interdisciplinary study included a reconstruction of the geomorphological and environmental history of Drayton Island, wood provenance and dendrochronology studies, research on house architecture and settlement patterns, and a zooarchaeological analysis. This paper synthesizes the preliminary results of this interdisciplinary investigation within the context of climate change. We discuss the persistence of semi-subterranean dwellings in eastern Hudson Bay long after they had been abandoned elsewhere. At Qijurittuq, their abandonment corresponds with the end of Little Ice Age. However, at the same time, the development of more permanent contact with Euro-Canadians was having a strong impact upon Inuit culture.     

Compact,concurrent, and contiguous: smart growth and 50 years of residential planning in the Toronto region

In this article, we use parcel-based land-use data to analyze 50 years of residential development in the Toronto region. We test two hypotheses: (1) Toronto’s form does not conform to conventional definitions of suburban sprawl and (2) Toronto’s suburban development shows high levels of continuity over time with relatively high densities and mixed housing types. Contrary to recent research suggesting a convergence of urban forms among North American metropolitan regions, Ontario’s robust planning system has created a distinctive, highly consistent pattern of residential development that has, for half a century, achieved many of the core goals of smart growth including relatively compact, contiguous, and concurrent development. This form continues to be automobile dependent, however, and is not producing many of the benefits ascribed to smart growth. Rather than continuing to adopt United States-inspired smart growth policies, a more ambitious set of initiatives will be required to address current regional challenges.     

Assessment of global warming on the island of Tenerife, Canary Islands (Spain). Trends in minimum, maximum and mean temperatures since 1944

Temperature variation is studied at different altitudes and orientation on the island of Tenerife, according to the trends in the mean, maximum and minimum at 21 meteorological stations. Reference series are obtained by sectors, along with a representative overall series for Tenerife, in which temperature shows a statistically significant growth trend of 0.09?±?0.04°C/decade since 1944. Night-time temperatures have risen most (0.17°C?±?0.04°C/decade), while by day they have been more stable. Consequently, the diurnal temperature range between day and night has narrowed. By regions, warming has been much more intense in the high mountains than the other sectors below the inversion layer between 600 and 1,400?m altitude, and progressively milder towards the coast. The temperature rise on the windward (north-northeast) slopes is greater than on the leeward side and could be related to the increase in cloudiness on the northern side. The general warming of the island is less than in continental areas at between 24 and 44oN, being closer to the sea surface temperature in the same area. This is probably explained largely by the insular conditions. In fact warming is more evident in the high mountains (0.14?±?0.07°C/decade), where the tempering effect of the ocean and the impact of changes in the stratocumulus is weaker, being similar to the mean continental values in the northern hemisphere.     

Complexing capacity of the nutrient medium and its relation to inhibition of algal photosynthesis by copper

The toxic effect of copper on phytoplankton production is investigated in waters having different complexing capacities. It is demonstrated that a water’s complexing capacity does not guarantee that an equivalent amount of copper could be tolerated without adversely affecting algal production. Possible explanations for these findings are offered and discussed. It is deduced that ionic copper probably is already toxic to planktonic algae at concentrations of about 10^?10 mole/l.     

Bioenergy potentials from forestry in 2050

The purpose of this study was to evaluate the global energy production potential of woody biomass from forestry for the year 2050 using a bottom-up analysis of key factors. Woody biomass from forestry was defined as all of the aboveground woody biomass of trees, including all products made from woody biomass. This includes the harvesting, processing and use of woody biomass. The projection was performed by comparing the future demand with the future supply of wood, based on existing databases, scenarios, and outlook studies. Specific attention was paid to the impact of the underlying factors that determine this potential and to the gaps and uncertainties in our current knowledge. Key variables included the demand for industrial roundwood and woodfuel, the plantation establishment rates, and the various theoretical, technical, economical, and ecological limitations related to the supply of wood from forests. Forests, as defined in this study, exclude forest plantations. Key uncertainties were the supply of wood from trees outside forests, the future rates of deforestation, the consumption of woodfuel, and the theoretical, technical, economical, or ecological wood production potentials of the forests. Based on a medium demand and medium plantation scenario, the global theoretical potential of the surplus wood supply (i.e., after the demand for woodfuel and industrial roundwood is met) in 2050 was calculated to be 6.1 Gm³ (71 EJ) and the technical potential to be 5.5 Gm³ (64 EJ). In practice, economical considerations further reduced the surplus wood supply from forests to 1.3 Gm³ year⁻¹ (15 EJ year⁻¹). When ecological criteria were also included, the demand for woodfuel and industrial roundwood exceeded the supply by 0.7 Gm³ year⁻¹ (8 EJ year⁻¹). The bioenergy potential from logging and processing residues and waste was estimated to be equivalent to 2.4 Gm³ year⁻¹ (28 EJ year⁻¹) wood, based on a medium demand scenario. These results indicate that forests can, in theory, become a major source of bioenergy, and that the use of this bioenergy can, in theory, be realized without endangering the supply of industrial roundwood and woodfuel and without further deforestation. Regional shortages in the supply of industrial roundwood and woodfuel can, however, occur in some regions, e.g., South Asia and the Middle East and North Africa.