Radiative effects of cirrus clouds

August, 1973.Includes bibliographical references (pages 58-59).Sponsored by the National Science Foundation. GA-36302

Gyroscopic stabilisers for powered two-wheeled vehicles

© 2018, © 2018 Informa UK Limited, trading as Taylor & Francis Group. This paper illustrates the potential of a gyroscopic stabiliser for the stabilisation of single-track vehicles, at low and high speed as well as during braking. Alternative systems are considered, including single and twin counter-rotating gyroscopes, spinning and precessing with respect to different axes, either freely (passive stabilisers) or in a controlled way (active stabilisers). A suitable mathematical model has been developed and stability has been investigated both by eigenvalue calculation and time domain simulations. It has been found that the most effective configuration is one where the gyroscope(s) spin with respect to an axis parallel to the wheels' spin axis and swing with respect to the vehicle yaw axis. Passive systems may effectively stabilise both weave and wobble at medium and high speed, but cannot stabilise the vehicle at low and zero speed. On the contrary, actively controlled gyroscopes are capable of stabilising the vehicle in its whole range of operating speed, as well as during braking. The alteration of the original vehicle handling characteristics is negligible when active counter-rotating gyroscopes are used, and still acceptable if a single gyroscope is adopted instead

Remote functionalisation via sodium alkylamidozincate intermediates : access to unusual fluorenone and pyridyl ketone reactivity patterns

Treating fluorenone or 2-benzoylpyridine with the sodium zincate [(TMEDA)center dot Na(mu-Bu-t)(mu-TMP)Zn(Bu-t)] in hexane solution, gives efficient Bu-t addition across the respective organic substrate in a highly unusual 1,6-fashion, producing isolable organometallic intermediates which can be quenched and aerobically oxidised to give 3-tert-butyl-9H-fluoren-9-one and 2-benzoyl-5-tert-butylpyridine respectively

SNP Discovery and Genomic Architecture of Highly Inbred Leghorn and Fayoumi Chicken Breeds Using Whole Genome Resequencing

Advances in the use of next generation sequencing (NGS) and ability to pool individuals into groups that represent distinct livestock populations has made it possible to examine trait differences between breeds of chicken. The breeds examined are very divergent when compared on their history of laying ability and immune response. The long-term objective is to understand the genetic differences between the Leghorn and Fayoumi breeds for use in developing more productive and disease resistant chickens. Statistical testing of the sequence of the two breeds along with Gene set enrichment analysis (GSEA) to make connections between the genetic variation seen in the NGS data and the breed specific traits of egg laying and heightened immune response can be used to characterize these two breeds. Genetic terms having the highest level of differentiation between the lines appear to group into metabolic processes, with terms over-enriched for immune system process, sexual reproduction, and growth for variants examined between lines. Terms for functions within the Fayoumi and Leghorn populations aligned to immune function and reproductive function, respectively. These results are consistent with known breed phenotypes and provide a means to focus on specific DNA variations and the birds’ genetic diversity that are potentially of more commercial importance

The Analysis of Commercially Available Kratom Products in Richmond, Virginia

Kratom is a novel psychoactive substance that has gained popularity within the past ten years. Originating from Southeast Asia, the leaves of the Mitragyna speciosa tree contain two principal alkaloids, mitragynine and 7-hydroxymitragynine, that play a key role in opioid-like effects. Twenty-nine kratom products were obtained from tobacco shops in the Richmond, Virginia area, including powders, teas, capsules, extracts, and a carbonated beverage. Samples were analyzed using Direct Analysis in Real Time-Mass Spectrometry (DART-MS) for kratom alkaloids, labeled ingredients, and other possible organic compounds. Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES) was used to quantitate aluminum, arsenic, copper, iron, magnesium, nickel, and lead with yttrium as the internal standard. Mitragynine and 7-hydroxymitragynine were present in every kratom sample. Kratom tea samples were found to have up to 20 times the tolerable upper intake of manganese. Overexposure to manganese can lead to Parkinsonian symptoms including tremors, dystonia, and facial muscle spasms. Gas Chromatography-Mass Spectrometry (GC-MS) was used to qualitatively confirm the presence of alkaloids and differentiate diastereomers. One non-kratom product was analyzed and was found to contain phenibut, an anxiolytic and nootropic substance. Phenibut was not listed on the label of this product. This work contributes to bring attention to the absence of quality control standards on kratom manufacturers as well as proper labeling of products sold at smoke and tobacco shops, prompting a public health concern due to the association of toxic metal levels in commercial kratom products.https://scholarscompass.vcu.edu/gradposters/1175/thumbnail.jp

A reduced complexity numerical method for optimal gate synthesis

Although quantum computers have the potential to efficiently solve certain problems considered difficult by known classical approaches, the design of a quantum circuit remains computationally difficult. It is known that the optimal gate design problem is equivalent to the solution of an associated optimal control problem, the solution to which is also computationally intensive. Hence, in this article, we introduce the application of a class of numerical methods (termed the max-plus curse of dimensionality free techniques) that determine the optimal control thereby synthesizing the desired unitary gate. The application of this technique to quantum systems has a growth in complexity that depends on the cardinality of the control set approximation rather than the much larger growth with respect to spatial dimensions in approaches based on gridding of the space, used in previous literature. This technique is demonstrated by obtaining an approximate solution for the gate synthesis on $SU(4)$- a problem that is computationally intractable by grid based approaches.Comment: 8 pages, 4 figure

CFCI3 (CFC-11): UV Absorption Spectrum Temperature Dependence Measurements and the Impact on Atmospheric Lifetime and Uncertainty

CFCl3 (CFC-11) is both an atmospheric ozone-depleting and potent greenhouse gas that is removed primarily via stratospheric UV photolysis. Uncertainty in the temperature dependence of its UV absorption spectrum is a significant contributing factor to the overall uncertainty in its global lifetime and, thus, model calculations of stratospheric ozone recovery and climate change. In this work, the CFC-11 UV absorption spectrum was measured over a range of wavelength (184.95 - 230 nm) and temperature (216 - 296 K). We report a spectrum temperature dependence that is less than currently recommended for use in atmospheric models. The impact on its atmospheric lifetime was quantified using a 2-D model and the spectrum parameterization developed in this work. The obtained global annually averaged lifetime was 58.1 +- 0.7 years (2 sigma uncertainty due solely to the spectrum uncertainty). The lifetime is slightly reduced and the uncertainty significantly reduced from that obtained using current spectrum recommendation

Density Waves Excited by Low-Mass Planets in Protoplanetary Disks I: Linear Regime

Density waves excited by planets embedded in protoplanetary disks play a central role in planetary migration and gap opening processes. We carry out 2D shearing sheet simulations to study the linear regime of wave evolution with the grid-based code Athena, and provide detailed comparisons with the theoretical predictions. Low mass planets (down to ~0.03 Earth mass at 1 AU) and high spatial resolution (256 grid points per scale height) are chosen to mitigate the effects of wave nonlinearity. To complement the existing numerical studies, we focus on the primary physical variables such as the spatial profile of the wave, torque density, and the angular momentum flux carried by the wave, instead of secondary quantities such as the planetary migration rate. Our results show percent level agreement with theory in both physical and Fourier space. New phenomena such as the change of the toque density sign far from the planet are discovered and discussed. Also, we explore the effect of the numerical algorithms, and find that a high order of accuracy, high resolution, and an accurate planetary potential are crucial to achieve good agreement with the theory. We find that the use of a too large time-step without properly resolving the dynamical time scale around the planet produces incorrect results, and may lead to spurious gap opening. Global simulations of planet migration and gap opening violating this requirement may be affected by spurious effects resulting in e.g. the incorrect planetary migration rate and gap opening mass.Comment: single column, 44 pages, 12 figures, ApJ in press, minor corrections mad

Numerical Solution of the Dynamic Programming Equation for the Optimal Control of Quantum Spin Systems

The purpose of this paper is to describe the numerical solution of the Hamilton-Jacobi-Bellman (HJB) for an optimal control problem for quantum spin systems. This HJB equation is a first order nonlinear partial differential equation defined on a Lie group. We employ recent extensions of the theory of viscosity solutions from Euclidean space to Riemannian manifolds to interpret possibly non-differentiable solutions to this equation. Results from differential topology on the triangulation of manifolds are then used to develop a finite difference approximation method, which is shown to converge using viscosity solution techniques. An example is provided to illustrate the method.Comment: 11 pages, 5 figure