Recent progress in VSTOL technology

Progress in vertical and short takeoff and landing (V/STOL) aircraft technology, in particular, during the 1970 to 1980 period at Ames Research Center is discussed. Although only two kinds of V/STOL aircraft (the helicopter and the British direct lift Harrier) have achieved operational maturity, understanding of the technology has vastly improved during this 10 year period. To pursue an aggressive R and D program at a reasonable cost, it was decided to conduct extensive large scale testing in wind tunnel and flight simulation facilities, to develop low cost research aircraft using modified airframes or engines, and to involve other agencies and industry contractors in joint technical and funding arrangements. The STOL investigations include exploring STOL performance using the rotating cylinder flap concept, the augmentor wing, upon initiation of the Quiet Short Haul Research Aircraft program, the upper surface blown flap concept. The VTOL investigations were conducted using a tilt rotor aircraft, resulting in the XV-15 tilt rotor research aircraft. Direct jet lift is now being considered for application to future supersonic fighter aircraft

Involving Adults in the Learning of Mathematics

Preparing adults for the mathematics skills necessary for the twenty first century is a challenge. It is especially challenging if those adults have had past traumatic experiences learning mathematics. Involving students in the learning process involves more than the presentation of mathematical concepts by the teacher and the simple regurgitation of rote memorization by the students. It requires a concerted effort by both the teacher and the student. The teacher must present mathematical concepts that are inclusionary, challenging, in an environment created for learning, in class settings that are technologically advanced, and geared to the student\u27s level. The student must assimilate the information through cooperative learning exercises and writing assignments, which incorporate the learning objectives of the current class and the ideas learned in previous classes

Large-scale wind-tunnel tests of descent performance of an airplane model with a tilt wing and differential propeller thrust

Wind tunnel tests of wing stall, performance, and longitudinal stability & control of large model v/stol tilt wing transport aircraf

Method of statistical filtering

Minimal formula for bounding the cross correlation between a random forcing function and the state error when this correlation is unknown is used in optimal linear filter theory applications. Use of the bound results in overestimation of the estimation-error covariance

Generalized solutions and distributional shadows for Dirac equations

We discuss the application of recent results on generalized solutions to the Cauchy problem for hyperbolic systems to Dirac equations with external fields. In further analysis we focus on the question of existence of associated distributional limits and derive their explicit form in case of free Dirac fields with regularizations of initial values corresponding to point-like probability densities

Surface- and tip-enhanced Raman spectroscopy reveals spin-waves in iron oxide nanoparticles

Nanomaterials have the remarkable characteristic of displaying physical properties different from their bulk counterparts. An additional degree of complexity and functionality arises when oxide nanoparticles interact with metallic nanostructures. In this context the Raman spectra due to plasmonic enhancement of iron oxide nanocrystals are here reported showing the activation of spin-waves. Iron oxide nanoparticles on gold and silver tips are found to display a band around 1584 cm−1 attributed to a spin-wave magnon mode. This magnon mode is not observed for nanoparticles deposited on silicon (111) or on glass substrates. Metal–nanoparticle interaction and the strongly localized electromagnetic field contribute to the appearance of this mode. The localized excitation that generates this mode is confirmed by tip-enhanced Raman spectroscopy (TERS). The appearance of the spin-waves only when the TERS tip is in close proximity to a nanocrystal edge suggests that the coupling of a localized plasmon with spin-waves arises due to broken symmetry at the nanoparticle border and the additional electric field confinement. Beyond phonon confinement effects previously reported in similar systems, this work offers significant insights on the plasmon-assisted generation and detection of spin-waves optically induced

In vivo expression and purification of aptamer-tagged small RNA regulators

Small non-coding RNAs (sRNAs) are an emerging class of post-transcriptional regulators of bacterial gene expression. To study sRNAs and their potential protein interaction partners, it is desirable to purify sRNAs from cells in their native form. Here, we used RNA-based affinity chromatography to purify sRNAs following their expression as aptamer-tagged variants in vivo. To this end, we developed a family of plasmids to express sRNAs with any of three widely used aptamer sequences (MS2, boxB, eIF4A), and systematically tested how the aptamer tagging impacted on intracellular accumulation and target regulation of the Salmonella GcvB, InvR or RybB sRNAs. In addition, we successfully tagged the chromosomal rybB gene with MS2 to observe that RybB-MS2 is fully functional as an envelope stress-induced repressor of ompN mRNA following induction of sigmaE. We further demonstrate that the common sRNA-binding protein, Hfq, co-purifies with MS2-tagged sRNAs of Salmonella. The presented affinity purification strategy may facilitate the isolation of in vivo assembled sRNA-protein complexes in a wide range of bacteria

Antimicrobial use and resistance and the relationship with health and biosecurity status in CIPARS data from Canadian grower-finisher swine herds

Antimicrobial resistance (AMR) is a global threat to public and animal health. The Canadian Integrated Program for Antimicrobial Resistance Surveillance (CIPARS), created in 2002, is a national program dedicated to the collection, integration, analysis, and communication of trends in antimicrobial use (AMU) and resistance (AMR) in selected bacteria from humans, animals, and animal-derived food sources across Canada. This information supports (i) the creation of evidence‐based policies for AMU in hospitals, communities, and food‐animal production with the aim of prolonging the effectiveness of these drugs and (ii) the identification of appropriate measures to contain the emergence and spread of resistant bacteria among animals, food, and people

Detection of protein glycosylation using tip enhanced Raman scattering

The correct glycosylation of biopharmaceutical glycoproteins and their formulations is essential for them to have the desired therapeutic effect on the patient. It has recently been shown that Raman spectroscopy can be used to quantify the proportion of glycosylated protein from mixtures of native and glycosylated forms of bovine pancreatic ribonuclease (RNase). Here we show the first steps towards not only the detection of glycosylation status, but the characterisation of glycans themselves from just a few protein molecules at a time using tip-enhanced Raman scattering (TERS). Whilst this technique generates complex data that are very dependent on the protein orientation, with the careful development of combined data preprocessing, univariate and multivariate analysis techniques, we have shown that we can distinguish between the native and glycosylated forms of RNase. Many glycoproteins contain populations of subtly different glycoforms, therefore with stricter orientation control, we believe this has the potential to lead to further glycan characterisation using TERS, which would have use in biopharmaceutical synthesis and formulation research