From detailed to summary models of the crop-soil system for larger scale applications

Crop growth models developed at field level are increasingly used in larger scale studies often in combination with other models to explore management options at the whole-farm scale or for integrated assessment at regional level (e.g. Giller et al., 2006; van Ittersum et al., 2008). Unclear is whether the mechanistic detail of dynamic simulation crop models is required for such applications or whether summary models may be sufficient. To address this issue and to identify relationships that need specific attention in future research, we compared simulations of crop production by two models with a different degree of mechanistic detail. (Résumé d'auteur

Sensation Seeking and Perceived Need for Structure Moderate Soldiers’ Well-Being Before and After Operational Deployment

This study examined associations between sensation seeking and perceived need for structure, and changes in reported well-being among deployed soldiers. Participants (n = 167) were assessed before and after a six-month deployment to south Afghanistan. Results indicated that although well-being declined in the soldier sample as a whole following deployment, the degree of decrease was significantly different among soldiers with different personality profiles. Differences were moderated by soldiers’ level of sensation seeking and perceived need for structure. Results are discussed in terms of a person-environment fit theory in the context of preparation and rehabilitation of deployed military personnel

On the Contribution of Higher Azimuthal Modes to the Near- and Far-Field of Jet Mixing Noise

The prediction of jet mixing noise is studied using a stochastic realization of the Tam & Auriault source model. The acoustical sources are generated by means of the Random Particle-Mesh Method (RPM), which utilizes turbulence statistics as provided by solu- tions to the Reynolds Averaged Navier-Stokes (RANS) equations. The generated stochas- tic sound sources closely realize the two-point cross-correlation function used in the jet noise model to prescribe the fine-scale sound source. The RPM code is coupled with the DLR CAA solver PIANO. The azimuthal-modal decomposed linearized Euler equations are applied as governing equations. With this approach, it is possible to evaluate jet noise spectra at any position in the near-field. Based on an azimuthal decomposition, 3-D sound radiation from the jet can be reproduced at the computational price of a few axisymmetric 2-D computations. Furthermore, it will be shown, that we are able to verify the imple- mented methodology with the results published for the genuine model. The spectra are correctly predicted in terms of sound pressure levels, Mach scaling exponent and spectral shape. A Strouhal number range of up to St = 10 can be covered using the first six az- imuthal mode components of the broadband source. To reach higher Strouhal numbers more azimuthal modes have to be adopted. The presented results reveal the importance of individual azimuthal contributions to the total spectra. To evaluate the spectra in the far-field, the generated near-field noise is extrapolated with a modal Ffowcs-Williams & Hawkings (FWH) method. For the static single stream jet (Ma = 0.9) two different kinds of extrapolation were used - a simplified extrapolation and the modal FWH method. With this computational case, it was possible to predict a jet noise spectrum in the range of St = 0.01 . . . 20. To investigate the effect of different nozzle configurations on sound gener- ation, different nozzle configurations, i.e. dual-stream nozzles with and without nozzle lip treatments are simulated. Good agreement with experimental data for the noise reduction potential of nozzle lip treatments is found

Population studies of migratory birds in Virgin Islands National Park

The majority of the individual songbirds nesting in the deciduous forests of eastern North America migrate to the West Indies, Central America and South America during the winter. They typically spend more than six months in tropical winter habitats. Until recently relatively little was known about their habitat requirements during the winter, but increasing concern about declining pcpulations of many migratory songbirds combined with widespread alarm about the rapid destruction of tropical forests has led to a flurry of research on this subject (Terborgh, 1989; Askins et al. 1990). In 1987 we initiated a study of the ecology and behavior of migrants in the Virgin Islands, particularly in Virgin Islands NP on St. John. This study has not only yielded information about the winter ecology of migratory birds, but also about the distribution of resident species and (unexpectedly) the impact of a major hurricane on bird populations

Flocking behavior of migratory warblers in winter in the Virgin Islands

We assessed the flocking behavior of birds on St. John and St. Thomas, U.S. Virgin Islands, with systematic surveys along trails in moist forests. Winter residents (species breeding in North America and that winter in the Virgin Islands), all of which were warblers, comprised 91% of the individuals found in 28 flocks but only 49% of solitary individuals. The average flock size was 4.0 individuals of 3.1 species, and did not differ between St. John and St. Thomas even though the average forest tract on St. John (1,000 ha) was much larger than on St. Thomas (62 ha). Northern Parula (Parula americana) and Black-and-white Warbler (Mniotilta varia), the most common species in flocks, occurred in 76% and 79% of the flocks, respectively. Northern Parula flocked significantly more frequently on St. Thomas than on St. John, but no other species showed a difference in flocking behavior between the two islands. Each flock typically included one individual of each species

Johnson Space Center's Solar and Wind-Based Renewable Energy System

The NASA Johnson Space Center (JSC) in Houston, Texas has a Sustainability Partnership team that seeks ways for earth-based sustainability practices to also benefit space exploration research. A renewable energy gathering system was installed in 2007 at the JSC Child Care Center (CCC) which also offers a potential test bed for space exploration power generation and remote monitoring and control concepts. The system comprises: 1) several different types of photovoltaic panels (29 kW), 2) two wind-turbines (3.6 kW total), and 3) one roof-mounted solar thermal water heater and tank. A tie to the JSC local electrical grid was provided to accommodate excess power. The total first year electrical energy production was 53 megawatt-hours. A web-based real-time metering system collects and reports system performance and weather data. Improvements in areas of the CCC that were detected during subsequent energy analyses and some concepts for future efforts are also presented

Exploring efficacy in personal constraint negotiation: an ethnography of mountaineering tourists

Limited work has explored the relationship between efficacy and personal constraint negotiation for adventure tourists, yet efficacy is pivotal to successful activity participation as it influences people’s perceived ability to cope with constraints, and their decision to use negotiation strategies. This paper explores these themes with participants of a commercially organised mountaineering expedition. Phenomenology-based ethnography was adopted to appreciate the social and cultural mountaineering setting from an emic perspective. Ethnography is already being used to understand adventure participation, yet there is considerable scope to employ it further through researchers immersing themselves into the experience. The findings capture the interaction between the ethnographer and the group members, and provide an embodied account using their lived experiences. Findings reveal that personal mountaineering skills, personal fitness, altitude sickness and fatigue were the four key types of personal constraint. Self-efficacy, negotiation-efficacy and other factors, such as hardiness and motivation, influenced the effectiveness of negotiation strategies. Training, rest days, personal health, and positive self-talk were negotiation strategies. A conceptual model illustrates these results and demonstrates the interplay between efficacy and the personal constraint negotiation journey for led mountaineers

Climate change adaptation in agriculture; the use of multi-scale modelling and stakeholder participation in the Netherlands

Abstract about a research project to develop a methodology to assess adaptation of agriculture to climatic and socio-economic changes at multiple scales, with a first application in the Province of Flevoland, the Netherlands