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%

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

Impact of the Wiggler Coherent Synchrotron Radiation Impedance on the Beam Instability

Coherent Synchrotron Radiation (CSR) can play an important role by not only increasing the energy spread and emittance of a beam, but also leading to a potential instability. Previous studies of the CSR induced longitudinal instability were carried out for the CSR impedance due to dipole magnets. However, many storage rings include long wigglers where a large fraction of the synchrotron radiation is emitted. This includes high-luminosity factories such as DAPHNE, PEP-II, KEK-B, and CESR-C as well as the damping rings of future linear colliders. In this paper, the instability due to the CSR impedance from a wiggler is studied assuming a large wiggler parameter $K$. The primary consideration is a low frequency microwave-like instability, which arises near the pipe cut-off frequency. Detailed results are presented on the growth rate and threshold for the damping rings of several linear collider designs. Finally, the optimization of the relative fraction of damping due to the wiggler systems is discussed for the damping rings.Comment: 10 pages, 7 figure

Creating the ‘ethics industry': Mary Warnock, in vitro fertilization and the history of bioethics in Britain

Recent decades have seen a shift in the management and discussion of biomedicine. Issues once considered by doctors and scientists are now handled by a diverse array of participants, including philosophers, lawyers, theologians and lay representatives. This new approach, known as ‘bioethics', has become the norm in regulatory committees and public debate. In this article, I argue that bioethics emerged as a valued enterprise in Britain during the 1980s because it fulfilled, and linked, the concerns of several groups. My analysis centres on the moral philosopher Mary Warnock, who chaired a government inquiry into human fertilization and embryology between 1982 and 1984, and became a strong advocate of bioethics. I detail how Warnock's promotion of bioethics tallied with the Conservative government's desire for increased surveillance of hitherto autonomous professions – while fulfilling her own belief that philosophers should engage in public affairs. And I also show that Warnock simultaneously promoted bioethics to doctors and scientists as an essential safeguard against declining political and public trust. This stance, I argue, framed bioethics as a vital intermediary between politics, the public, and biomedicine, and explains the growth and endurance of what the Guardian identified as an ethics industry

Sodium Transport in Capillaries Isolated from Rat Brain

Brain capillary endothelial cells form a bloodbrain barrier (BBB) that appears to play a role in fluid and ion homeostasis in brain. One important transport system that may be involved in this regulatory function is the Na + ,K + -ATPase that was previously demonstrated to be present in isolated brain capillaries. The goal of the present study was to identify additional Na + transport systems in brain capillaries that might contribute to BBB function. Microvessels were isolated from rat brains and 22 Na + uptake by and efflux from the cells were studied. Total 22 Na + uptake was increased and the rate of 22 Na + efflux was decreased by ouabain, confirming the presence of Na + ,K + -ATPase in capillary cells. After inhibition of Na + ,K + -ATPase activity, another saturable Na + transport mechanism became apparent. Capillary uptake of 22 Na + was stimulated by an elevated concentration of Na + or H + inside the cells and inhibited by extracellular Na + , H + , Li + , and NH 4 + . Amiloride inhibited 22 Na + uptake with a K i between 10 −5 and 10 −6 M but there was no effect of 1 mM furosemide on 22 Na + uptake by the isolated microvessels. These results indicate the presence in brain capillaries of a transport system capable of mediating Na + / Na + and Na + /H + exchange. As a similar transport system does not appear to be present on the luminal membrane of the brain capillary endothelial cell, it is proposed that Na + /H + exchange occurs primarily across the antiluminal membrane.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66187/1/j.1471-4159.1983.tb09065.x.pd

Simplified citrate anticoagulation for continuous renal replacement therapy

Simplified citrate anticoagulation for continuous renal replacement therapy.BackgroundRegional anticoagulation with trisodium citrate is an effective form of anticoagulation for continuous renal replacement therapy (CRRT) for patients with contraindications to heparin. However, because of the metabolic complications of trisodium citrate, it is a complicated technique requiring specialized dialysis solutions. We have designed a simplified protocol for citrate regional anticoagulation for CRRT.MethodsTwo percent trisodium citrate was delivered at 250 mL/h via the prefilter port of a COBE PRISMA device, with the rate adjusted to maintain a postfilter ionized calcium (iCa++) <0.5mmol/L. A central calcium gluconate infusion was used to maintain a systemic iCa++ at 1.1mmol/L. A standard dialysate solution consisting of 0.9% saline, KCl 3mmol/L, and MgSO4 1mmol/L was delivered at 1000 mL/h. We retrospectively reviewed the outcomes and complications associated with this protoco1 in 29 patients treated from July 1999 to October 1999, evaluating the frequency of clotting of the dialyzer, bleeding complications, citrate toxicity, and patient mortality.ResultsThe Kaplan–Meier curve for dialyzer survival demonstrated a 61% survival rate at 48 hours. There were no episodes of significant bleeding or citrate toxicity. Seventy-two percent of patients died for reasons unrelated to CRRT.ConclusionsA CRRT protocol using regional 2% trisodium citrate anticoagulation is not associated with significant bleeding complications or citrate toxicity, and represents a simplified approach compared with previous applications using 4% trisodium citrate