A comparison of vertical velocities measured from specular and nonspecular echoes by a VHF radar

For a number of years, there have been doubts about the accuracy of vertical wind velocities measured with quasi-specular reflections from mesosphere-stratosphere-troposphere (MST) radar. The concern has been that the layers producing the quasi-specular reflection process this hypothetical tilt. Because of the quasi-specular reflection process, this hypothetical tilt would control the effective zenith angle of the radar antenna beam so that a small component of the horizontal velocity would be included in what was assumed to be a truly vertical beam. The purpose here is to test the hypothesis that there is an effect on the wind velocities measured on a vertical antenna beam due to a long-term tilting of the stable atmospheric layers that cause quasi-specular reflection. Gravity waves have been observed to cause short-term tilting of turbulent layers and specularly reflecting layers. In both cases, the effect was a wave-like deformation atmospheric layers with a period of a few minutes. This geometry is shown. Because of this influence of gravity waves, it was expected that there would be short-term variations in the vertical velocity

Teachers' perceptions of how attention-deficit/hyperactivity disorder may influence learners' career choices

This article reports on teachers’ perceptions of how ADHD may influence learners’ career choices. Purposive selection was used to identify six high school teachers who cater specifically for learners with Attention-Deficit/Hyperactivity Disorder (ADHD). An exploratory case study design and a qualitative approach were adopted. Data was gathered using an audio-recorded semi-structured focus group interview, and analysed and interpreted using inductive thematic analysis. Findings suggest teachers believe that ADHD affects parents, schooling, and the school environment from an early age, that taking medication for ADHD from an early age may positively and negatively influence affect learners’ career choices, and that intervention to address the longer-term impact of ADHD on learners’ career choices is essential. Moreover, teachers believe that parents play a powerful role in the career choice of learners with ADHD. Future research should include early childhood carers, teachers and other health professionals, and include larger and more diverse groups of participants

Study of an advanced transport airplane design concept known as Flatbed

The design concept and configuration of the Flatbed transport aircraft are presented. The Flatbed configuration combines into one frame, the ability to haul cargo, virtually unrestrained by cross sectional dimensions of the fuselage. The feasibility and capability of the Flatbed is discussed in depth

An Analytical Study for Subsonic Oblique Wing Transport Concept

The oblique wing concept has been investigated for subsonic transport application for a cruise Mach number of 0.95. Three different mission applications were considered and the concept analyzed against the selected mission requirements. Configuration studies determined the best area of applicability to be a commercial passenger transport mission. The critical parameter for the oblique wing concept was found to be aspect ratio which was limited to a value of 6.0 due to aeroelastic divergence. Comparison of the concept final configuration was made with fixed winged configurations designed to cruise at Mach 0.85 and 0.95. The crossover Mach number for the oblique wing concept was found to be Mach 0.91 for takeoff gross weight and direct operating cost. Benefits include reduced takeoff distance, installed thrust and mission block fuel and improved community noise characteristics. The variable geometry feature enables the final configuration to increase range by 10% at Mach 0.712 and to increase endurance by as much as 44%

Safety and efficacy of enzyme replacement therapy in the nephropathy of Fabry disease

Kidney involvement with progressive loss of kidney function (Fabry nephropathy) is an important complication of Fabry disease, an X-linked lysosomal storage disorder arising from deficiency of α-galactosidase activity. Clinical trials have shown that enzyme replacement therapy (ERT) with recombinant human α-galactosidase clears globotriaosylceramide from kidney cells, and can stabilize kidney function in patients with mild to moderate Fabry nephropathy. Recent trials show that patients with more advanced Fabry nephropathy and overt proteinuria do not respond as well to ERT alone, but can benefit from anti-proteinuric therapy given in conjunction with ERT. This review focuses on the use of enzyme replacement therapy with agalsidase-alfa and agalsidase-beta in adults with Fabry nephropathy. The current results are reviewed and evaluated. The issues of dosing of enzyme replacement therapy, the use of adjunctive agents to control urinary protein excretion, and the individual factors that affect disease severity are reviewed

Examining brook trout invasion into bull trout streams of the Canadian Rockies

xiv, 184 leaves : ill. ; 29 cmBrook trout invasion into bull trout streams is variable, and likely influenced by a suite of biotic and abiotic factors. Field observations revealed that brook trout dominated the fish community over bull trout in warmer sites that had undercut banks; in contrast, bull trout dominated in colder sites that had a high amount of large substrate cover, and where alternate non-native species were present. Laboratory studies of competition between the two species revealed that bull trout use a scramble foraging tactic, whereas brook trout use a territorial tactic. Bull trout outcompeted brook trout when fish density was low and habitat complexity was high, as this scenario reduced the effectiveness of the aggressive territorial foraging strategy of brook trout. Bull trout from a migratory population competed more successfully against brook trout and had higher rates of oxygen consumption than those from a resident population. This combined field-lab study points to some of the abiotic and biotic factors that affect competition between the two species, and may influence the outcome of brook trout invasion into bull trout streams

Measurement of vertical velocity using clear-air Doppler radars

A new clear air Doppler radar was constructed, called the Flatland radar, in very flat terrain near Champaign-Urbana, Illinois. The radar wavelength is 6.02 m. The radar has been measuring vertical velocity every 153 s with a range resolution of 750 m almost continuously since March 2, 1987. The variance of vertical velocity at Flatland is usually quite small, comparable to the variance at radars located near rough terrain during periods of small background wind. The absence of orographic effects over very flat terrain suggests that clear air Doppler radars can be used to study vertical velocities due to other processes, including synoptic scale motions and propagating gravity waves. For example, near rough terrain the shape of frequency spectra changes drastically as the background wind increases. But at Flatland the shape at periods shorter than a few hours changes only slowly, consistent with the changes predicted by Doppler shifting of gravity wave spectra. Thus it appears that the short period fluctuations of vertical velocity at Flatland are alsmost entirely due to the propagating gravity waves