Master of Science

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Broadband laser cooling of trapped atoms with ultrafast pulses

We demonstrate broadband laser cooling of atomic ions in an rf trap using ultrafast pulses from a modelocked laser. The temperature of a single ion is measured by observing the size of a time-averaged image of the ion in the known harmonic trap potential. While the lowest observed temperature was only about 1 K, this method efficiently cools very hot atoms and can sufficiently localize trapped atoms to produce near diffraction-limited atomic images

The labor market regimes of Denmark and Norway – one Nordic model?

The literature on the Danish and Norwegian labor market systems emphasizes the commonalities of the two systems. We challenge this perception by investigating how employers in multinational companies in Denmark and Norway communicate with employees on staffing changes. We argue that the development of ‘flexicurity’ in Denmark grants Danish employers considerably greater latitude in engaging in staffing changes than its Nordic counterpart, Norway. Institutional theory leads us to suppose that large firms located in the Danish setting will be less likely to engage in employer–employee communication on staffing plans than their Norwegian counterparts. In addition, we argue that in the Danish context indigenous firms will have a better insight into the normative and cognitive aspects to flexicurity than foreign-owned firms, meaning that they are more likely to engage in institutional entrepreneurialism than their foreign owned counterparts. We supplement institutional theory with an actor perspective in order to take into account the role of labor unions. Our analysis is based on a survey of 203 firms in Norway and Denmark which are either indigenous multinational companies or the subsidiaries of foreign multinational companies. The differences we observe cause us to conclude that the notion of a common Nordic model is problematic

Crew Exploration Vehicle Ascent Abort Coverage Analysis

An important element in the design of NASA's Crew Exploration Vehicle (CEV) is the consideration given to crew safety during various ascent phase failure scenarios. To help ensure crew safety during this critical and dynamic flight phase, the CEV requirements specify that an abort capability must be continuously available from lift-off through orbit insertion. To address this requirement, various CEV ascent abort modes are analyzed using 3-DOF (Degree Of Freedom) and 6-DOF simulations. The analysis involves an evaluation of the feasibility and survivability of each abort mode and an assessment of the abort mode coverage using the current baseline vehicle design. Factors such as abort system performance, crew load limits, thermal environments, crew recovery, and vehicle element disposal are investigated to determine if the current vehicle requirements are appropriate and achievable. Sensitivity studies and design trades are also completed so that more informed decisions can be made regarding the vehicle design. An overview of the CEV ascent abort modes is presented along with the driving requirements for abort scenarios. The results of the analysis completed as part of the requirements validation process are then discussed. Finally, the conclusions of the study are presented, and future analysis tasks are recommended

Spatiotemporal Dynamics of Mediterranean Shallow Coastal Fish Communities Along a Gradient of Marine Protection

The importance of habitat factors in designing marine reserves and evaluating their performance over time has been regularly documented. Over three biennial sampling periods, we examined the effects of vegetated coverage and habitat diversity (i.e., patchiness) on fish density, community composition, and species-specific patterns along a gradient of protection from harvest in the shallow Spanish southern Mediterranean, including portions of the Tabarca marine reserve. With the exception of two herbivores (Sarpa salpa and Symphodus tinca), vegetated cover did not significantly affect fish densities, while habitat diversity was an influential factor across all three sampling periods. Overall, fish density was more positively associated with more continuous vegetated or unvegetated habitats, and was greatest in areas of highest protection (Tabarca II – Isla Nao site). These patterns were usually observed for four abundant fish species (Boops boops, Chromis chromis, Oblada melanura, and S. salpa). Fish community composition was distinct in the most protected portion of the Tabarca reserve, where it was also most stable. Our findings align with previous investigations of the Tabarca reserve and its surrounding areas, and demonstrate its continued effectiveness in conserving fish biomass and habitat. Together with effective management, marine reserves can facilitate greater species abundance, more stable biological communities, and resilient ecosystems