Light levitated geostationary cylindrical orbits are feasible

This paper discusses a new family of non-Keplerian orbits for solar sail spacecraft displaced above or below the Earth's equatorial plane. The work aims to prove the assertion in the literature that displaced geostationary orbits exist, possibly to increase the number of available slots for geostationary communications satellites. The existence of displaced non-Keplerian periodic orbits is ¯rst shown analytically by linearization of the solar sail dynamics around a geostationary point. The full displaced periodic solution of the non-linear equations of motion is then obtained using a Hermite-Simpson collocation method with inequality path constraints. The initial guess to the collocation method is given by the linearized solution and the inequality path constraints are enforced as a box around the linearized solution. The linear and nonlinear displaced periodic orbits are also obtained for the worst-case Sun-sail orientation at the solstices. Near-term and high-performance sails can be displaced between 10 km and 25 km above the Earth's equatorial plane during the summer solstice, while a perforated sail can be displaced above the usual station-keeping box (75 £ 75 km) of nominal geostationary satellites. Light-levitated orbit applications to Space Solar Power are also considered

Three method factors explaining the low correlations between assessment center dimension ratings and scores on personality inventories

In general, correlations between assessment centre (AC) ratings and personality inventories are low. In this paper, we examine three method factors that may be responsible for these low correlations: differences in (i) rating source (other versus self), (ii) rating domain (general versus specific), and (iii) rating format (multi- versus single item). This study tests whether these three factors diminish correlations between AC exercise ratings and external indicators of similar dimensions. Ratings of personality and performance were combined in an analytical framework following a 2 × 2 × 2 (source, domain, format) completely crossed, within subjects design. Results showed partial support for the influence of each of the three method factors. Implications for future research are discussed. Copyright © 2004 John Wiley & Sons, Ltd

Expression patterns of semaphorin7A and plexinC1 during rat neural development suggest roles in axon guidance and neuronal migration

Contains fulltext : 84465.pdf (publisher's version ) (Open Access

Technisch rapport WO-Monitor 1998

In 1998 is onder auspiciën van de VSNU de WO-Monitor van start gegaan. Aanleiding hiervoor was de behoefte om over landelijke gegevens te beschikken met betrekking tot de arbeidsmarktintrede van afgestudeerden. Weliswaar werd op diverse plaatsen reeds onderzoek verricht naar de overgang van het WO naar de arbeidsmarkt, maar door de uiteenlopende designs en vraagstellingen leverde dit geen onderling vergelijkbare gegevens op. Het Algemeen Bestuur van de VSNU heeft daarom besloten tot invoering van een landelijke WO-Monitor, waarin alle universiteiten participeren.labour market entry and occupational careers;