Reduction of trimmed drag

Methods are reported for reducing the aircraft drag coefficient for a given aircraft lift coefficient, or speed. The emphasis is placed in determining the load distribution between the wing-body combination and the tail which reduces overall drag coefficient. Furthermore, a technique is presented which allows the determination of various aerodynamic and geometric parameters to permit the best location to satisfy inherent stability requirements. Included in the method is the calculation of sensitivity coefficients which indicate the importance of various parameters in achieving specified goals. Preliminary results indicate that such an approach is feasible

Curved flow wind tunnnel test of F-18 aircraft

The curved flow capability of a stability wind tunnel was used to investigate the lateral directional characteristics of an F-18 aircraft. The model is described and the procedures used to obtain and correct the data and a graphical presentation of the results are presented. The results include graphs of lateral directional derivatives versus sideslip or static plots, the lateral directional static stability derivatives versus angle of attack, and finally the lateral directional derivatives versus nondimensional yaw rate for different angles of attack and sideslip. Results are presented for several configurations including complete, complete without vertical tails, complete without horizontal tails, fuselage wing and fuselage alone. Each of these were tested with and without wing leading edge extensions

Rolling flow wind tunnel tests of F-18 aircraft

The lateral directional characteristics of an F-18 aircraft was investigated. Aerodynamic derivatives associated with pure roll rate, or the 'p' derivatives were obtained. The model is described and the procedures used to obtain and correct the data, and a graphical presentation of the results are presented. These results include graphs of the lateral directional static stability derivatives versus angle of attack, and the lateral directional force and moment coefficients versus nondimensional roll rate. Results are presented for several configurations including complete, complete without vertical tails, complete without horizontal tails, fuselage wing and fuselage alone. Each of these configuations was tested with and without wing leading edge extensions. The basic control surfaces were deflected and the results were investigated

Do interventions using threshold concepts assist learning in Biology?

The current interest in threshold concepts in the disciplines (Meyer & Land 2003, 2005) may provide a powerful heuristic for academics to help students to pass through conceptual gateways associated with previously inaccessible and possibly troublesome ways of thinking. Meyer and Land used three critical descriptors to identify threshold concepts, namely being transformative, irreversible and integrative experiences which are typified by cognitive and ontological shifts often accompanied by an extension of the student's use of language. Ross et al (2009), as part of an ALTC funded research project on Threshold Concepts in Biology, have developed a framework of discipline and threshold concepts which identifies a web of threshold concepts in biology, some of which are equivalent to epistemes. Interventions were then designed, to test the threshold properties of one of these concepts, which we predicted would assist students to make the link between the submicroscopic and the macroscopic cellular world and their connections at various spatial scales. All students in an introductory molecular and cellular biology course, offered in their first year at university, were surveyed at the commencement of the course about their conceptual understanding of scale. Half this cohort was then given two different interventions relating to scale and the remainder were provided with material similar in format, but which only reinforced relevant curricular content. Students were then surveyed following these interventions to determine the effectiveness of the intervention. Our results demonstrate the effectiveness of such an intervention in assessing whether once students cross one threshold, in a context such as cells and protein synthesis, they can subsequently transfer this way of thinking to aid in crossing thresholds in other contexts and other similarly difficult concepts in biology

Increased risk of venous thromboembolism in patients with acute leukaemia

Patients with malignancies have an increased risk for venous thromboembolisms (VTE), but data on patients with acute leukaemia are very limited so far. We found VTE in 12% of 455 patients with acute leukaemia, half of which occurred in association with central venous catheters, with equal risk of ALL and AML

Sur les solutions périodiques du mouvement plan de libration des satellites et des planètes

Ce papier présente une étude analytique du mouvement plan de rotation des satellites (et des planètes) dans leurs mouvements orbitaux. Les trois familles des solution périodiques sont obtenues par la méthode du prolongement analytique de Poincaré. Ensuite, la stabilité de ces solutions périodiques est discutée, et les équations approchées des courbes limites de stabilité sont données jusqu'au quatrième ordre. This paper presents an analytical study of the rotational motion of the satellites (and the planets) in their orbital planes. The three families of periodic solutions are obtained by the method of analytical continuation as formulated by Poincaré. The stability of these solutions are analyzed, and the approximate equations of the transition curves are obtained to the fourth order.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/42563/1/10569_2005_Article_BF01227807.pd

Rethinking naive realism

Perceptions are externally-directed - they present us with a mind-independent reality, and thus contribute to our abilities to think about this reality, and to know what is objectively the case. But perceptions are also internally-dependent - their phenomenal characters depend on the neuro-computational properties of the subject. A good theory of perception must account for both these facts. But Naive realism has been criticized for failing to accommodate the latter one. This paper evaluates and responds to this criticism. It first argues that a certain version of naive realism, often called “selectionism”, does indeed struggle with the internal-dependence of perceptions. It then develops an alternate version of naive realism which does not. This alternate version, inspired by an idea of Martin's, accommodates the internal-dependence of perceptions by recognizing the role that the subject's neuro-computational properties play in shaping perceptual phenomenology. At the same time, it retains the distinctive naive realist account of the external-directedness of perceptions