The evolution of comet orbits

The origin of comets and the evolution of their orbits are discussed. Factors considered include: the law of survival of comets against ejection on hyperbolic orbits; short-period comets are not created by single close encounters of near-parabolic comets with Jupiter; observable long-period comets do not evolve into observable short-period comets; unobservable long-period comets with perihelia near Jupiter can evolve into observable short-period comets; long-period comets cannot have been formed or created within the planetary region of the solar system (excluding the effects of stellar perturbations); it is possible that some of the short-period comets could have been formed inside the orbit of Neptune; circularly-restricted three-body problem, and its associated Jacobi integral, are not valid approximations to use in studying origin and evolution of comets

Persistence pays off: Sir Charles Oatley and the scanning electron microscope

Shortly after World War II, Sir Charles Oatley initiated research at the Cambridge University engineering laboratories on what has evolved into the modern scanning electron microscope. While much of the research was actually conducted by research students under Oatley's supervision, he continually provided ideas, resources, and encouragement. He then was instrumental in having this instrument commercialized. His students often continued in the field for some time, making contributions both to the instrument and to its applications that led to improved performance and wider acceptance. This article attempts to capture some of the accomplishments of Sir Charles Oatley as seen by those who worked closely with him. The author believes that Sir Charles deserves the title: "Father of the Modern Scanning Electron Microscope.

Empathy Activators: Strategies for Developing Empathy in Service-Learning Students

This poster presentation explores the link between service-learning and the development of student empathy. It will share the initial research results of a pilot study on student empathy, service-learning, and key ingredients for cultivating empathy. It also offers instructors concrete ideas for teaching tools that activate student empathy

A one-dimensional Fermi accelerator model with moving wall described by a nonlinear van der Pol oscillator

A modification of the one-dimensional Fermi accelerator model is considered in this work. The dynamics of a classical particle of mass $m$, confined to bounce elastically between two rigid walls where one is described by a non-linear van der Pol type oscillator while the other one is fixed, working as a re-injection mechanism of the particle for a next collision, is carefully made by the use of a two-dimensional non-linear mapping. Two cases are considered: (i) the situation where the particle has mass negligible as compared to the mass of the moving wall and does not affect the motion of it; (ii) the case where collisions of the particle does affect the movement of the moving wall. For case (i) the phase space is of mixed type leading us to observe a scaling of the average velocity as a function of the parameter ($\c{hi}$) controlling the non-linearity of the moving wall. For large $\c{hi}$, a diffusion on the velocity is observed leading us to conclude that Fermi acceleration is taking place. On the other hand for case (ii), the motion of the moving wall is affected by collisions with the particle. However due to the properties of the van der Pol oscillation, the moving wall relaxes again to a limit cycle. Such kind of motion absorbs part of the energy of the particle leading to a suppression of the unlimited energy gain as observed in case (i). The phase space shows a set of attractors of different periods whose basin of attraction has a complicate organization

Asthma-Related Anxiety and Quick-Relief Medication Use in Urban Children with Asthma

Among children, asthma is the most common chronic illness. Although not curable, asthma is manageable with the use of both daily controller medication and quick relief or rescue medication. Anxiety has been found to increase asthma symptoms in children. Caregivers who are anxious about their child’s asthma symptoms may perceive their child’s asthma as more severe or doubt their ability to manage their child’s asthma, which can result in the misuse of asthma medication. This study focused on the association between asthma-related anxiety and the use of quick-relief asthma medications in a low-income, urban sample in Richmond, Virginia. Child participants range in age from 7 to 12 years old (M=9.5 years, standard deviation (SD) =1.5). Data were collected from 53 families and 89% of the child participants from these families were African American/Black (8% Caucasian/White, 3% mixed/multiracial). Caregivers and children completed questionnaires at an initial baseline visit. Caregivers then completed surveys on a cell phone and measured their child’s lung function with an AM2 device for two weeks. We had three main hypotheses: 1) If a parent had high levels of asthma-related anxiety, then their child would have higher levels of asthma-related anxiety 2) If the parent had high levels of asthma-related anxiety, then the parent would provide the child with higher levels of quick relief asthma medications, and 3) If the child had high levels of asthma-related anxiety, then the child would receive a higher number of quick relief puffs. Hypotheses were analyzed while controlling for asthma control. Findings suggested that there was no significant association between parent and child asthma-related anxiety. A significant association was found between parent asthma-related anxiety and number of quick relief puffs such that higher levels of anxiety was associated with more rescue medication. However, this association was not significant when controlling for asthma control. The association between child asthma-related anxiety and number of quick relief puffs was also not significant. These findings are important to consider when looking at a child with asthma because poor asthma management could be associated with parent asthma-related anxiety. Other studies have suggested that if physicians are made aware of parent and child asthma-related anxiety levels, they could work with the families to determine the most appropriate way to approach asthma management techniques to best fit their specific circumstances. Further, our results suggest the importance of focusing on child anxiety in addition to parent anxiety as children and parents may be reporting different levels of anxiety related to asthma.https://scholarscompass.vcu.edu/uresposters/1122/thumbnail.jp

The clinical pharmacology of intranasal l-methamphetamine.

BackgroundWe studied the pharmacology of l-methamphetamine, the less abused isomer, when used as a nasal decongestant.Methods12 subjects self-administered l-methamphetamine from a nonprescription inhaler at the recommended dose (16 inhalations over 6 hours) then at 2 and 4 (32 and 64 inhalations) times this dose. In a separate session intravenous phenylephrine (200 microg) and l-methamphetamine (5 mg) were given to define alpha agonist pharmacology and bioavailability. Physiological, cardiovascular, pharmacokinetic, and subjective effects were measured.ResultsPlasma l-methamphetamine levels were often below the level of quantification so bioavailability was estimated by comparing urinary excretion of the intravenous and inhaled doses, yielding delivered dose estimates of 74.0 +/- 56.1, 124.7 +/- 106.6, and 268.1 +/- 220.5 microg for ascending exposures (mean 4.2 +/- 3.3 microg/inhalation). Physiological changes were minimal and not dose-dependent. Small decreases in stroke volume and cardiac output suggesting mild cardiodepression were seen.ConclusionInhaled l-methamphetamine delivered from a non-prescription product produced minimal effects but may be a cardiodepressant

Constraining multiple systems with GAIA

GAIA will provide observations of some multiple asteroid and dwarf systems. These observations are a way to determine and improve the quantification of dynamical parameters, such as the masses and the gravity fields, in these multiple systems. Here we investigate this problem in the cases of Pluto's and Eugenia's system. We simulate observations reproducing an approximate planning of the GAIA observations for both systems, as well as the New Horizons observations of Pluto. We have developed a numerical model reproducing the specific behavior of multiple asteroid system around the Sun and fit it to the simulated observations using least-square method, giving the uncertainties on the fitted parameters. We found that GAIA will improve significantly the precision of Pluto's and Charon's mass, as well as Petit Prince's orbital elements and Eugenia's polar oblateness.Comment: 5 pages, accepted by Planetary and Space Science, Gaia GREAT-SSO-Pis

Orbital structure of the GJ876 extrasolar planetary system, based on the latest Keck and HARPS radial velocity data

We use full available array of radial velocity data, including recently published HARPS and Keck observatory sets, to characterize the orbital configuration of the planetary system orbiting GJ876. First, we propose and describe in detail a fast method to fit perturbed orbital configuration, based on the integration of the sensitivity equations inferred by the equations of the original $N$-body problem. Further, we find that it is unsatisfactory to treat the available radial velocity data for GJ876 in the traditional white noise model, because the actual noise appears autocorrelated (and demonstrates non-white frequency spectrum). The time scale of this correlation is about a few days, and the contribution of the correlated noise is about 2 m/s (i.e., similar to the level of internal errors in the Keck data). We propose a variation of the maximum-likelihood algorithm to estimate the orbital configuration of the system, taking into account the red noise effects. We show, in particular, that the non-zero orbital eccentricity of the innermost planet \emph{d}, obtained in previous studies, is likely a result of misinterpreted red noise in the data. In addition to offsets in some orbital parameters, the red noise also makes the fit uncertainties systematically underestimated (while they are treated in the traditional white noise model). Also, we show that the orbital eccentricity of the outermost planet is actually ill-determined, although bounded by $\sim 0.2$. Finally, we investigate possible orbital non-coplanarity of the system, and limit the mutual inclination between the planets \emph{b} and \emph{c} orbits by $5^\circ-15^\circ$, depending on the angular position of the mutual orbital nodes.Comment: 36 pages, 11 figures, 3 tables; Accepted to Celestial Mechanics and Dynamical Astronom

Empathy Activators: Teaching Tools for Enhancing Empathy Development in Service-Learning Classes

On February 5, 2016, 25 educators from Virginia Commonwealth University (VCU) and the University of Richmond (UR) gathered in Richmond, Virginia, for an annual service-learning workshop. This year’s workshop featured Robin Everhart, PhD, VCU assistant professor of psychology, as keynote speaker. Jumpstarted by Everhart’s research on student empathy, workshop participants explored the concept of empathy and collaboratively developed strategies for integrating empathy into the service-learning experience. This document grows out of Everhart’s presentation and group discussions during that workshop and represents a collection of ideas generated