OH-selected AGB and post-AGB stellar objects II.Blue versus red evolution off the AGB

Using objects found in a systematic survey of the galactic Plane in the 1612-MHz OH line, we discuss in detail two ``sequences'' of post-AGB evolution, a red and a blue. We argue that the red and the blue groups separate by initial mass at 4Msun, based on evolutionary-sequence turn-off colours, spectral energy distributions, outflow velocities and scaleheight. The higher-mass (blue) objects may have earlier AGB termination. The lower-mass (red) objects undergo very sudden reddening for IRAS colour R21\sim1.2; these sources must all undergo a very similar process at AGB termination. The transition colour corresponds to average initial masses of 1.7Msun. A combined IRAS-MSX colour proves a very sensitive tool to distinguish lower-mass, early post-AGB objects from sources still on the AGB and also to distinguish more evolved post-AGB objects from star-forming regions. The high-mass blue objects are the likely precursors of bipolar planetary nebulae, whereas the low-mass red objects will evolve into elliptical planetary nebulae.Comment: 12 pages, LaTex, 7 figures (1 colour), AJ (accepted

The role of social interaction in farmers' climate adaptation choice

Adaptation to climate change might not always occur, with potentially\ud catastrophic results. Success depends on coordinated actions at both\ud governmental and individual levels (public and private adaptation). Even for a “wet” country like the Netherlands, climate change projections show that the frequency and severity of droughts are likely to increase. Freshwater is an important factor for agricultural production. A deficit causes damage to crop production and consequently to a loss of income. Adaptation is the key to decrease farmers’ vulnerability at the micro level and the sector’s vulnerability at the macro level. Individual adaptation decision-making is determined by the behavior of economic agents and social interaction among them. This can be best studied with agentbased modelling. Given the uncertainty about future weather conditions and the costs and effectiveness of adaptation strategies, a farmer in the model uses a cognitive process (or heuristic) to make adaptation decisions. In this process, he can rely on his experiences and on information from interactions within his social network. Interaction leads to the spread of information and knowledge that causes learning. Learning changes the conditions for individual adaptation decisionmaking. All these interactions cause emergent phenomena: the diffusion of adaptation strategies and a change of drought vulnerability of the agricultural sector. In this paper, we present a conceptual model and the first implementation of an agent-based model. The aim is to study the role of interaction in a farmer’s social network on adaptation decisions and on the diffusion of adaptation strategies\ud and vulnerability of the agricultural sector. Micro-level survey data will be used to parameterize agents’ behavioral and interaction rules at a later stage. This knowledge is necessary for the successful design of public adaptation strategies, since governmental adaptation actions need to be fine-tuned to private adaptation behavior

Blocking a wave: Frequency band gaps in ice shelves with periodic crevasses

We assess how the propagation of high-frequency elastic-flexural waves through an ice shelf is modified by the presence of spatially periodic crevasses. Analysis of the normal modes supported by the ice shelf with and without crevasses reveals that a periodic crevasse distribution qualitatively changes the mechanical response. The normal modes of an ice shelf free of crevasses are evenly distributed as a function of frequency. In contrast, the normal modes of a crevasse-ridden ice shelf are distributed unevenly. There are "band gaps", frequency ranges over which no eigenmodes exist. A model ice shelf that is 50 km in lateral extent and 300 m thick with crevasses spaced 500 m apart has a band gap from 0.2 to 0.38 Hz. This is a frequency range relevant for ocean wave/ice-shelf interactions. When the outermost edge of the crevassed ice shelf is oscillated at a frequency within the band gap, the ice shelf responds very differently from a crevasse-free ice shelf. The flexural motion of the crevassed ice shelf is confined to a small region near the outermost edge of the ice shelf and effectively "blocked" from reaching the interior.Comment: 6 pages, 4 figures, accepted to Annals of Glaciolog

OH-selected AGB and post-AGB objects I.Infrared and maser properties

Using 766 compact objects from a survey of the galactic Plane in the 1612-MHz OH line, new light is cast on the infrared properties of evolved stars on the TP-AGB and beyond. The usual mid-infrared selection criteria, based on IRAS colours, largely fail to distinguish early post-AGB stages. A two-colour diagram from narrower-band MSX flux densities, with bimodal distributions, provides a better tool to do the latter. Four mutually consistent selection criteria for OH-masing red PPNe are given, as well as two for early post-AGB masers and one for all post--AGB masers, including the earliest ones. All these criteria miss a group of blue, high-outflow post-AGB sources with 60-mum excess; these will be discussed in detail in Paper II. The majority of post-AGB sources show regular double-peaked spectra in the OH 1612-MHz line, with fairly low outflow velocities, although the fractions of single peaks and irregular spectra may vary with age and mass. The OH flux density shows a fairly regular relation with the stellar flux and the envelope optical depth, with the maser efficiency increasing with IRAS colour R21. The OH flux density is linearly correlated with the 60-mum flux density.Comment: 16 pages, LaTex, 22 figures, AJ (accepted

The peacebuilding potential of technical and vocational education and training programmes in post-conflict Sierra Leone

In peacebuilding contexts unemployed youth are frequently perceived as a high risk for the stability of a country while employed youth are seen as carrying an enormous potential for economic growth. This paper applies a social justice framework (4Rs) in analysing a Business Development (BD) programme that was implemented as part of Sierra Leone’s Technical and Vocational Education and Training (TVET) strategy to promote entrepreneurship development and reduce unemployment among youth. Despite the BD programme’s initial strengths, to recognize youth's heterogeneity with the aim to address some of the root causes of the war, we show how the programme struggled to counter social inequality, unemployment and neopatrimonialism. Sudden decreases in donor funding led to severe modifications of redistribution processes, thereby hampering youth's representation. This raises questions about the design of TVET strategies and BD programmes in post-conflict settings in general. Our paper further showcases how the resurfacing of the root causes of a conflict in the scope of small-scheme development programmes, can have far-reaching effects on young people’s various relationships of trust, if not reconciliation process as a whole

Flood risk perceptions applied to a spatial multi-criteria analysis in the Ebro Delta in Spain

The conventional method of risk analysis (with risk as a product of probability and consequences) does not allow for a pluralistic approach that includes the various risk perceptions of stakeholders or lay people within a community or region. In river basins, it is often an expert-based economic analysis of land use values that serves as the underlying estimation of costs. Intangibles such as nature development, biodiversity and cultural heritage are difficult to include in the calculation. Yet, local knowledge can be used to develop a realistic approach to outweighing tangibles and intangibles of land use values, as well as developing new approaches to risk management. This can be important to find appropriate solutions for the mitigation of risk. This presentation introduces a methodology that combines the virtues of three different methods used for risk analysis: the quantifiable conventional approach to risk, the taxonomic analysis of perceived risk and the analytical framework of a spatial multicriteria analysis. The combination of these methods is applied to the case study ’Ebro Delta’ in Spain as part of the European 6th framework project ’Floodsite’. The new approach using this combination is the incorporation of risk perceptions and its application and operationalisation in a multi-criteria analysis. Risk perception is derived from the psychometric paradigm that distinguishes a variety of risk characteristics. Due to a number of similarities among these risk perceptions all known risk characteristics can be condensed into three higher order risk characteristics - awareness, worry and preparedness. This reduction of risk characteristics enables scientists to employ them as weights in a multi-criteria analysis. Risk perception information has been collected with help of an on-site survey. The result is significant levels of ’worry’ and ’awareness’ of the flood risk with an increasing demand for ’preparedness’. Risk perception enters the multi-criteria analysis as complementary weights for the criteria risk and benefit. The results of the survey are applied to a set of scenarios representing both sea level rise and land subsidence for a time span of fifty years. Land use alternatives that are based upon the given scenarios have been presented to stakeholders and evaluated. For effective land use policy in flood prone areas it can be useful to compare land use alternatives based upon their performance with respect to risk and benefit. In this way the regional decision maker has been given an overview of preferences for handling risk. Even with limited resources a characteristic ’risk profile’ could be drawn that enables the decision maker to develop a suitable land use policy or at least provide a basis for further social learning processes

Gene-environment interactions in early life and adulthood : implications for cocaine intake

The objective of the research described in this thesis was to demonstrate the role of gene-environment interactions in the emergence of individual differences in cocaine use. For this purpose we used two inbred mouse strains, the C57Bl/6 (C57) and DBA/2 (DBA), which are known to differ in drug-intake and to be differentially sensitive to several stressors. We studied the impact of early life experiences (long-term influence) as well as a later life psychosocial stressor (short-term influence) on adult drug intake behavior in these two mouse strains. To study the impact of the early life environment, we manipulated the maternal environment of the mice by fostering them with non-related mother strains showing either high or low pup-oriented behaviour. The late life experience consisted of a short-lasting period of group housing in adulthood. Cocaine self-administration in mice with a C57 background was not affected by either changes in postnatal maternal environment or a short group housing experience in adulthood, while these same experiences did affect mice with a DBA background. As a first step towards the biological mechanisms underlying this gene-environment interaction we found that vasopressin was differentially regulated in the extended amygdala of the DBA mice.LEI Universiteit LeidenNWO/INSERM/ZON grants AH002G and 985-10-014 University of Bordeaux 2 Leiden/Amsterdam Center for Drug Research JE Jurriaanse Stichting Noldus Information Technology BV Top Institute PharmaUBL - phd migration 201