Visible-wavelength Observations of Jupiter-family Comet Nuclei as Part of Seppcon.

We present the latest analysis and results from SEPPCoN (Survey of Ensemble Physical Properties of Cometary Nuclei). This on-going survey involves studying 100 JFCs - about 25% of the known population - at both mid-infrared and visible wave-lengths to constrain the distributions of sizes, shapes, spins, and albedos of this population. Having earlier reported results from measuring thermal emissions of our sample nuclei [1,2,3,4], we report here progress on the visible-wavelength observations that we have obtained at many ground-based facilities in Chile, Spain, and the United States. To date we have attempted observations of 91% of our sample of 100 JFCs, and at least 64 of those were successfully detected. In most cases the comets were at heliocentric distances between 3.0 and 6.5 AU so as to decrease the odds of a comet having a coma. Of the 64 detected comets, 48 were apparently bare, having no extended emission. Our datasets are further augmented by archival data and photometry from the NEAT program [5]. An important goal of SEPPCoN is to accumulate a large comprehensive set of high quality physical data on cometary nuclei in order to make accurate statistical comparisons with other minor-body populations such as Trojans, Centaurs, and Kuiper-belt objects. Information on the size, shape, spin-rate, albedo and color distributions is critical for understanding their origins and evolutionary processes affecting them.

Postglacial formation and dynamics of North Patagonian Rainforest in the Chonos Archipelago, Southern Chile

Pollen analysis of continuous sediment cores from two lakes in the northern Chonos Archipelago (44S) in southern Chile shows a complete postglacial record of vegetation change. The fossil records indicate that deglaciation was complete in the northern Chonos by at least 13,600 14Cyr BP. Ericaceous heath and grassland persisted for more than 600 years after deglaciation under the influence of dry/cold climates and frequent burning. Nothofagus-Pilgerodendron-Podocarpus forest, with modern analogues in the southern Chonos Archipelago, was established across the northern islands by 12,400 14Cyr BP under increasingly warm and wet climates. There is no evidence for a return to cooler climates during the Younger Dryas chronozone. The rise of Tepualia stipularis and Weinmannia trichosperma as important forest components between 10,600 and 6000 14Cyr BP may be associated withclimates that were warmer than present. The collapse of Pilgerodendron communities during this time may have been triggered by a combination of factors related to disturbance frequency including tephra deposition events, fire and climate change. After 6000 14Cyr BP Pilgerodendron recovers and Nothofagus-Pilgerodendron-Tepualia forest persists until the present. European logging and burning activity may have increased the susceptibility of North Patagonian Rainforest to invasion by introduced species and to future collapse of the long-lived Pilgerodendron communities.

Between “the Housewife” and “the Philosophy Professor”: Music, Narration and Address in Ousmane Sembene's Xala

The acclaimed Senegalese filmmaker Ousmane Sembene conceptualised himself as a modern day griot (West African oral performer), producing often didactic films that address a diverse spectatorship. Examining Xala, this paper argues that this address cannot be fully understood without attention to the film’s complex music/image relationships, which refigure classical and modernist film aesthetics to mobilise a discourse that recalls oral performance. In this way, Sembene negotiates the tensions of address generated by a spectatorship that is situated in the culturally hybrid spaces between the literate and the oral, the urban and the rural, and the global and the local.

The Philosophy and Practice of Interpretivist Research in Entrepreneurship Quality, Validation, and Trust

Knowledge production in entrepreneurship requires inclusivity as well as diversity and pluralism in research perspectives and approaches. In this article, the authors address concerns about interpretivist research regarding validity, reliability, objectivity, generalizability, and communicability of results that militate against its more widespread acceptance. Following the nonfoundationalist argument that all observation is theory-laden, context specific, and that there are no external criteria against which to assess research design and execution and the data produced, the authors propose that quality must be internalized within the underlying research philosophy rather than something to be tested upon completion. This requires a shift from the notion of validity as an outcome to validation as a process. To elucidate this, they provide a guiding framework and present a case illustration that will assist an interpretivist entrepreneurship researcher to establish and demonstrate the quality of their work.

Assessment of bioavailable arsenic and copper in soils and sediments from the Antofagasta region of northern Chile

Copper levels of nearly 500 mg l(-1) were measured in aqueous extracts of soil and sediment samples from the lowlands of Antofagasta. Arsenic levels of up to 183 mg l(-1) were found in river sediments, and 27.5 mg l(-1) arsenic was found at the location of a dam where potable water is extracted. This indicates that the arsenic contamination of water supplies reported recently for the pre-Andes may be a widespread problem throughout the region. Copper contamination from smelting activities also provides cause for concern as elevated levels were found in aqueous extracts of soil up to 20 km away from a smelter. This study went beyond traditional chemical analysis by assessing the potential benefits of using microbial biosensors as an alternative to determination of chemical speciation, to provide an environmentally relevant interpretation of soil/sediment residue levels. This approach is simple to use and enables a rapid, low cost assessment of pollutant bioavailability. It may, therefore, be of use for further investigations in the region and beyond.