1,081 research outputs found
CO+ in M 82: A Consequence of Irradiation by X-rays
Based on its strong CO+ emission it is argued that the M 82 star-burst galaxy
is exposed to a combination of FUV and X-ray radiation. The latter is likely to
be the result of the star-burst superwind, which leads to diffuse thermal
emission at ~0.7 keV, and a compact hard, 2-10 keV, source (but not an AGN).
Although a photon-dominated region (FUV) component is clearly present in the
nucleus of M 82, and capable of forming CO+, only X-ray irradiated gas of
density 10^3-10^5 cm^-3 can reproduce the large, ~(1-4)x10^13 cm^-2, columns of
CO+ that are observed toward the proto-typical star-burst M 82. The total X-ray
luminosity produced by M 82 is weak, ~10^41 erg s^-1, but this is sufficient to
drive the formation of CO+.Comment: added discussion on more recent X-ray observation
East African governments' responses to high cereal prices
This study analyses the responses of governments in four East African countries (Kenya, Tanzania, Uganda and Ethiopia) with respect to price formation and price transmission in the cereal sector. All four countries were confronted with high cereal prices in 2008. Government policies applied largely pursued consumer price reduction, but such short-term price policies did not encourage farmers to respond with increasing production, the more so because farmers were facing very high fertiliser prices. The report concludes by discussing policy options to help improve market functioning which supports agricultural productivity growt
Are Dutch Water Safety Institutions Prepared for Climate Change?
This paper deals with the question to what extent the historically grown Dutch water safety institutions have the capacity to cope with the ‘new’ challenges of climate change. The Adaptive Capacity Wheel provides the methodological framework. The analysis focuses on three recent and major planning practices in the Dutch water safety domain: the development and implementation of the Room for the River project, the flood risk approach, and the Second Delta Plan, respectively. The paper concludes that for the Netherlands, to be prepared for climate change, it is necessary to take a new institutional path, by building capacity to improvise, by investing in and by creating room for collaborative leaders, and by finding ways to generate financial resources for long term innovative measure
Extragalactic H3O+: Some Consequences
We discuss some implications of our recent detection of extragalactic H3O+:
the location of the gas in M82, the origin of energetic radiation in M82, and
the possible feedback effects of star formation on the cosmic ray flux in
galaxies.Comment: Five pages, one figure; contribution to proceedings of conference
"Far-infrared observations of the interstellar medium", December 2007, Bad
Honne
Detection of extragalactic H3O+
The H3O+ molecule probes the oxygen chemistry and the ionization rate of
dense circumnuclear gas in galaxies. In particular, recent H3O+ observations
show variations in the cosmic-ray ionization rate by factors of 10 within
our Galaxy. Using the JCMT, we have observed the 364 GHz line of p-H3O+ in the
centers of M82 and Arp 220. In Arp 220, the line profile suggests that the
emission originates in the Western nucleus. In M82, both the eastern molecular
peak and the circumnuclear region contribute to the emission. The derived
column densities, abundances, and H3O+ / H2O ratios indicate ionization rates
similar to or even exceeding that in the Galactic Center. Model calculations of
the chemistry of irradiated molecular gas indicate a likely origin of this high
ionization rate in the extended, evolved starburst of M82. In contrast,
irradiation by X-rays from the AGN disk is the most likely model for Arp 220.Comment: Accepted by A&A Letters; 4-5 pages depending on paper format; two b/w
figure
What kind of leadership do we need for climate adaptation? : a framework for analyzing leadership functions and tasks in climate change adaptation
Agrarische handel van België met ontwikkelingslanden; Toets op duurzaamheid
Deze studie voor het Vlaamse ministerie van Landbouw en Visserij belicht de economische, sociale en ecologische gevolgen van agrarische handel van België met ontwikkelingslanden. Het onderzoek spitst zich toe op een vijftal producten (banaan, cacao, koffie, soja en thee) en vier ontwikkelingslanden (Brazilië, Costa Rica, Ivoorkust en Tanzania). Het oordeel over de mate van duurzaamheid wordt gebaseerd op de vier landenstudies, uitgevoerd door lokale onderzoekers, waarbij een beperkt aantal indicatoren is meegenomen. Naar voren komt dat met name de twee Latijns Amerikaanse landen negatieve ecologische gevolgen van handel (in soja en banaan) ondervinden, en dat in de Afrikaanse landen de negatieve sociaal-economische aspecten de meeste aandacht vragen. This study for the Flemish Ministry of Agriculture and Fisheries sheds light on the economic, social and ecological effects of Belgium's agricultural trade with developing countries. The study focuses on five products (bananas, cocoa, coffee, soya and tea) and four developing countries (Brazil, Costa Rica, Côte d'Ivoire and Tanzania). The assessment of the level of sustainability is based on the four country studies, conducted by local researchers, and taking into account a limited number of indicators. It emerges that the two Latin American countries experience negative ecological effects of trade (in soya and bananas), and that in the African countries the negative social-economic aspects require most attention
How Dutch Institutions Enhance the Adaptive Capacity of Society
This report examines the adaptive capacity of the institutional framework of the Netherlands to cope with the impacts of climate change. Historically, institutions have evolved incrementally to deal with existing social problems. They provide norms and rules for collective action and create continuity rather than change. However, the nature of societal problems is changing as a result of the processes of globalization and development. With the progress made in the natural sciences, we are able to predict in advance, to a certain extent, the potential environmental impacts of various human actions on society, for example, climate change. This raises some key questions: Are our institutions capable of dealing with this new knowledge about future impacts and, more importantly, with the impacts themselves? Are our institutions capable of dealing with the inherent uncertainty of the predictions
- …