Determining particle density using known material Hugeniot curves

A method is detailed to determine the density of particles wherein the closing velocity is known between the impacting particles and a plate of known material. Either the shock wave velocity or the material velocity produced in the plate upon impact by an unknown material particle is determined and compared with the corresponding shock wave or material velocity that would by produced by different known material particles having the same closing velocity upon impact with the plate. The unknown material particle density is derived by obtaining a coincidence of the shock wave velocity or material velocity conditions initially produced upon impact between the known material plate and one of the different material particles and from the fact that shock wave velocity and material velocity are ordered on the impacting particle material density alone

The Immediate Feedback Assessment Technique: A Learner-centered Multiple-choice Response Form

The Immediate Feedback Assessment Technique (IFAT) is a new multiple-choice response form that has advantages over more commonly used response techniques. The IFAT, which is commercially available at reasonable cost and can be used conveniently with large classes, has an answer-until-correct format that provides students with immediate, corrective, item-by-item feedback. Advantages of this learner-centered response form are that it: (a) actively promotes learning; (b) allows students’ partial knowledge to be rewarded with partial credit; (c) is strongly preferred by students over other response techniques; and (d) lets instructors more easily maintain the security of multiple choice (MC) items so that they can be reused from one semester to the next. The IFAT’s major shortcoming is that grading must be done manually because it does not yet have a compatible optical scanning device. Helpful suggestions are presented for instructors who may be considering using the IFAT for the first time. RÉSUMÉ La Technique D’Évaluation Immédiat (Immediate Feedback Assessment Technique ou IFAT) est un nouveau formulaire pour examens à choix multiple qui a plusieurs avantages. Le IFAT, disponible à un prix raisonable et convenable pour les cours suivis par de nombreux étudiants, est constitué d’un format dans lequel les édudiants selectionnent alternative-par- alternative parmi les choix disponibles jusqu’à ce que la réponse correcte soit indiquée. En suite, la correction est automatique et informe la réponse correcte immédiatement. Le IFAT a plusieurs avantages: (a) il favorise l’apprentissage; (b) les étudiants peuvent obtenir des points partiels avec connaissances partiels; (c) les étudiants préferent ce formulaire à comparer à autres formats à choix multiple; et (d) les instructeurs peuvent maintenir plus facilement leurs questions et alternatives en sécurité et les réutiliser au cours des prochaines sessions. Le défaut principal du IFAT est que la notation est manuele car il n’y a pas encore de lecteur optique compatible avec ce formulaire. Des suggestions utiles sont ici données pour les instructeurs qui envisagent d’utiliser cette technique pour la première fois.La Technique D’Évaluation Immédiat (Immediate Feedback Assessment Technique ou IFAT) est un nouveau formulaire pour examens à choix multiple qui a plusieurs avantages. Le IFAT, disponible à un prix raisonable et convenable pour les cours suivis par de nombreux étudiants, est constitué d’un format dans lequel les édudiants selectionnent alternative-paralternative parmi les choix disponibles jusqu’à ce que la réponse correcte soit indiquée. En suite, la correction est automatique et informe la réponse correcte immédiatement. Le IFAT a plusieurs avantages: (a) il favorise l’apprentissage; (b) les étudiants peuvent obtenir des points partiels avec connaissances partiels; (c) les étudiants préferent ce formulaire à comparer à autres formats à choix multiple; et (d) les instructeurs peuvent maintenir plus facilement leurs questions et alternatives en sécurité et les réutiliser au cours des prochaines sessions. Le défaut principal du IFAT est que la notation est manuele car il n’y a pas encore de lecteur optique compatible avec ce formulaire. Des suggestions utiles sont ici données pour les instructeurs qui envisagent d’utiliser cette technique pour la première fois

Election administration in Massachusetts

Thesis (M.A.)--Boston UniversityThis thesis seeks to determine whether or not the election laws of Massachusetts are adequate in terms of the two above mentioned considerations. This is accomplished by an analysis of the laws and court decisions and of the present practices in Massachusetts, based upon personal observations and conversations with town clerks and other administration officials

Determination of diffusion in polycrystalline platinum thin films

Grain boundary diffusion of titanium through platinum thin films has been carried out in the temperature range from 200 to 600 °C. Five different platinum/titanium bilayer thicknesses, from 35 to 800 Å Pt, were annealed in 5% O2/95% N2.5%O2/95%N2. The accumulation of titanium at the platinum surface layer was measured by x-ray photoelectron spectroscopy (XPS) to determine the grain boundary diffusion coefficient (Db).(Db). Diffusivity values were calculated based on two different analysis methods assuming type C kinetics. For Pt layers thicker than 200 Å, the activation energy (Qb)(Qb) for titanium diffusion was found to be 118±15 kJ/mol (1.22±0.16 eV). For Pt layers thinner than 200 Å, there was a thickness dependence on the diffusion kinetics, resulting in activation energies as low as 20±4 kJ/mol (0.21±0.04 eV). XPS results gave no evidence for any Pt-Ti alloy formation in these layers. The suppression of alloy formation may be attributed to the presence of oxygen at the Pt/Ti interface during layer deposition. The quantitative analysis of titanium interdiffusion in platinum provides valuable information regarding Pt/Ti surface concentrations in thin-film chemical sensors, and for understanding changes in operational characteristics of platinum electrodes. © 1999 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/69829/2/JAPIAU-86-9-4902-1.pd

Removal of spacecraft-surface particulate contaminants by simulated micrometeoroid impacts

A series of hypervelocity impacts has been conducted in an exploding lithium-wire accelerator to examine with a far-field holographic system the removal of particulate contaminants from external spacecraft surfaces subjected to micrometeoroid bombardment. The impacting projectiles used to simulate the micrometeoroids were glass spheres nominally 37 microns in diameter, having velocities between 4 and 17 km/sec. The particulates were glass spheres nominally 25, 50, and 75 microns in diameter which were placed on aluminum targets. For these test, particulates detached had velocities that were log-normally distributed. The significance of the log-normal behavior of the ejected-particulate velocity distribution is that the geometric mean velocity and the geometric standard deviation are the only two parameters needed to model completely the process of particles removed or ejected from a spacecraft surface by a micrometeoroid impact

Barotropic Vortex Pairs on a Rotating Sphere

Using a barotropic model in spherical geometry, we construct new solutions for steadily travelling vortex pairs and study their stability properties. We consider pairs composed of both point and finite-area vortices, and we represent the rotating background with a set of zonal strips of uniform vorticity. After constructing the solution for a single point-vortex pair, we embed it in a rotating background, and determine the equilibrium configurations that travel at constant speed without changing shape. For equilibrium solutions, we find that the stability depends on the relative strength (which may be positive or negative) of the vortex pair to the rotating background: eastward-travelling pairs are always stable, while westward-travelling pairs are unstable when their speeds approach that of the linear Rossby–Haurwitz waves. This finding also applies (with minor differences) to the case when the vortices are of finite area; in that case we find that, in addition to the point-vortex-like instabilities, the rotating background excites some finite-area instabilities for vortex pairs that would otherwise be stable. As for practical applications to blocking events, for which the slow westward pairs are relevant, our results indicate that free barotropic solutions are highly unstable, and thus suggest that forcing mechanisms must play an important role in maintaining atmospheric blocking events

Phylogeography, population structure and evolution of coral-eating butterflyfishes (Family Chaetodontidae, genus Chaetodon, subgenus Corallochaetodon)

Aim: This study compares the phylogeography, population structure and evolution of four butterflyfish species in the Chaetodon subgenus Corallochaetodon, with two widespread species (Indian Ocean – C. trifasciatus and Pacific Ocean – C. lunulatus), and two species that are largely restricted to the Red Sea (C. austriacus) and north-western (NW) Indian Ocean (C. melapterus). Through extensive geographical coverage of these taxa, we seek to resolve patterns of genetic diversity within and between closely related butterflyfish species in order to illuminate biogeographical and evolutionary processes. Location: Red Sea, Indian Ocean and Pacific Ocean. Methods: A total of 632 individuals from 24 locations throughout the geographical ranges of all four members of the subgenus Corallochaetodon were sequenced using a 605 bp fragment (cytochrome b) of mtDNA. In addition, 10 microsatellite loci were used to assess population structure in the two widespread species. Results: Phylogenetic reconstruction indicates that the Pacific Ocean C. lunulatus diverged from the Indian Ocean C. trifasciatus approximately 3 Ma, while C. melapterus and C. austriacus comprise a cluster of shared haplotypes derived from C. trifasciatus within the last 0.75 Myr. The Pacific C. lunulatus had significant population structure at peripheral locations on the eastern edge of its range (French Polynesia, Johnston Atoll, Hawai'i), and a strong break between two ecoregions of the Hawaiian Archipelago. The Indian Ocean C. trifasciatus showed significant structure only at the Chagos Archipelago in the central Indian Ocean, and the two range-restricted species showed no population structure but evidence of recent population expansion. Main conclusions: Patterns of endemism and genetic diversity in Corallochaetodon butterflyfishes have been shaped by (1) Plio-Pleistocene sea level changes that facilitated evolutionary divergences at biogeographical barriers between Indian and Pacific Oceans, and the Indian Ocean and Red Sea, and (2) semi-permeable oceanographic and ecological barriers working on a shorter time-scale. The evolution of range-restricted species (Red Sea and NW Indian Ocean) and isolated populations (Hawai'i) at peripheral biogeographical provinces indicates that these areas are evolutionary incubators for reef fishes

An american woman in Salpêtrière: Augusta Dejerine-Klumpe (1859- 1927) and the brain mapping

Augusta Dejerine-Klumpke è stata la prima donna ad essere ammessa all’internato degli ospedali parigini. Ebbe un’educazione cosmopolita e nacque negli Stati Uniti d’America. L’internato è tutt’oggi, un’istituzione molto importante nell’ambito della carriera ospedaliera dei medici francesi. Il lavoro più importante della sua vita venne svolto con il neurologo Jules Dejerine; uno studio sull’Anatomia del sistema nervoso.Augusta Dejerine-Klumpke was the first woman admitted to work in the psychiatric hospitals in France. She was born in the United States and she had a cosmopolitan education. Nowadays, psychiatric hospitals are important istitutions in the career paths of French doctors. The most significant work of Augusta Dejerine-Klumpke’s life was done with the neurologist Jules Dejerine; a research about the nervous system Anatomy

Assessing Intended Employee Behavior in Exit Interviews: Attitudinal and Status Effects

In order to assess the effects that attitudes toward particular aspects of work life and status (management vs . non-management) might have on the intended willingness to discuss issues during exit interviews, managerial and non-managerial workers were asked to evaluate their attitudes toward particular aspects of work life, as well as their willingness to discuss these issues during an exit interview. Results showed that status alone did not affect willingness to discuss issues, but that attitudes and status had an interactive effect on willingness