Fundamental Properties of Intensity, Form, and Motion Perception in the Visual Nervous Systems of Calliphora phaenicia and Musca domestica

Several classes of interneurons in the optic lobes and brain of the insects, Musca domestica and Calliphora phaenicia, have been studied in detail. Visual stimuli have been categorized on the basis of the properties of intensity, form, and motion. Response characteristics of the classes of neural units are described with respect to these three classes of visual stimuli. While those units that detect motion in select directions have a tonic response, form detection units have a phasic response only. Through correlation of the responses of these classes with visual stimuli, it is shown that these units integrate the responses of other units which have very small visual fields. The small-field units are presumed to integrate the output of a small group of adjacent retinula cells and to respond differentially to intensity, form, and motion. It is shown that the response of both form and motion detection units is independent of the direction of pattern intensity gradation. As a consequence of this independence, it is further shown that failure to detect motion properly must start at a spatial wavelength four times the effective sampling station spacing rather than twice as has been predicted previously

Inferring Microscopic Kinetic Rates from Stationary State Distributions.

We present a principled approach for estimating the matrix of microscopic transition probabilities among states of a Markov process, given only its stationary state population distribution and a single average global kinetic observable. We adapt Maximum Caliber, a variational principle in which the path entropy is maximized over the distribution of all possible trajectories, subject to basic kinetic constraints and some average dynamical observables. We illustrate the method by computing the solvation dynamics of water molecules from molecular dynamics trajectories

On induced birefringence in viscoelastic materials

Describing induced birefringence in viscoelastic materials based on constitutive assumptions for stress and dielectric propertie

Le paradoxe de la qualité académique : implications pour les universités et les politiques publiques

Cet article traite de mécanismes d’assurance de la qualité dans le système d’enseignement supérieur et propose une interprétation du peu d’engagement des professeurs dans les processus d’analyse de la qualité des cursus universitaires et de l’expérience d’apprentissage des étudiants. L’institution universitaire valorise les performances individuelles en enseignement et en recherche et non les efforts coopératifs des départements universitaires pour assurer la qualité de l’offre de formation. C’est donc un paradoxe de la qualité académique que l’on compare à celui du célèbre roman Catch 22. À la suite des évaluations des mécanismes d’assurance de la qualité et pour résoudre le paradoxe de la qualité académique, on propose une démarche basée sur les principes de l’organisation apprenante.This article presents a discussion of mechanisms for assuring the quality of higher education and proposes one interpretation of the lack of commitment by professors in the process of quality analysis of university programs and of students’ learning experiences. As an institution, the university values individual performance in teaching and research and not the cooperative efforts of university departments in assuring the quality of the training program. This paradox of academic quality can be compared with that of the well-known novel Catch 22. Following an evaluation of the mechanisms used to assure quality and to respond to the paradox of academic quality, the author proposes a procedure based on the principles of the learning organization.Este artículo discute sobre los mecanismos para asegurar la calidad académica en el sistema de enseñanza superior y propone una interpretación sobre la poca implicación de los profesores en el proceso de análisis y en la calidad de los cursos universitarios tanto como en la experiencia de aprendizaje de los estudiantes. La institución universitaria valoriza los desempeños individuales en la enseñanza y en la investigación y no los esfuerzos cooperativos que llevan a cabo los departamentos universitarios afin de asegurar la calidad en la oferta de la formación. Hay, entonces, una paradoja en la calidad académica que puede compararse a aquella de la célebre novela Catch 22. Siguiendo con las evaluaciones de los mecanismos para asegurar la calidad académica y para resolver la paradoja de la calidad académica, se propone un proceso de evaluación basado en los principios de la organización aprendiente.In diesem Beitrag werden die Mechanismen aufzeigt, die der Qualitätskontinuität im Hochschulsystem zu Grunde liegen. Darüber hinaus wird die Frage diskutiert, warum die Lehrenden der Qualitätsanalyse von Universitätscurricula sowie dem Lernverhalten der Studenten so wenig Interesse entgegen-bringen. Die Institution valorisiert vor allem die individuellen Lehr- und Forschungsleistungen, nicht aber die gemeinschaftlichen Bemühungen der Fachbereiche um die Qualität der Studienprogramme. Diese Situation stellt einen Paradox dar, der mit einem berühmten literarischen Paradox, wie ihn der Roman Catch 22 thematisiert, verglichen wird. Im Anschluss an die kritische Auseinandersetzung mit den Qualitätsmechanismen und dem Paradox akademischer Lehrqualität wird eine Problemlösung vorgeschlagen, die auf dem Prinzip der Lernorganisation („l’organisation apprenante“) beruht

Identification of Chlamydial Iron-Responsive Proteins during Intracellular Growth.

Chlamydia trachomatis is an obligate intracellular bacterium and the most prevalent cause of bacterial sexually transmitted disease. Genital chlamydial infections, marked by chronic, intense inflammation, can lead to genital tissue scarring and infertility and is a contributing factor to development of pelvic inflammatory disease and ectopic pregnancy. Iron is required as a cofactor for numerous highly conserved pathways, and nearly all studied organisms rely on iron for growth. In response to iron restriction, the chlamydial developmental cycle arrests at the intracellular reticulate body stage, resulting in a phenomenon termed persistence. Persistence likely plays a role in chlamydial pathogenesis through the expression of virulence factors and antigens in addition to sustaining chronic infection; however, little is known concerning how chlamydiae respond to iron limitation at the molecular level, and no systems for iron acquisition have been identified in Chlamydia. This dissertation presents an investigation into the chlamydial response to iron restriction. Chlamydial heat shock protein 60 (cHsp60) has been implicated in development of the more severe disease sequelae and has been found to increase in expression following iron restriction; however, three cHsp60 homologues were identified following the sequencing of the chlamydial genome. Here, iron restriction is shown to increase expression of cHsp60-2 but not the two other homologs, cHsp60-1 or -3. Next, in order to investigate an alternate model for restricting iron availability to chlamydiae, a cell line with inducible expression of recombinant ferroportin, a eukaryotic iron efflux protein, was examined. Lastly, 10 chlamydial proteins differentially expressed during growth in iron-restricted host cells were identified by proteomic analysis of radiolabeled proteins followed by mass spectrometry analysis; transcripts encoding 5 iron responsive proteins were examined across a timecourse of infection and revealed increased transcript levels at 18 and/or 24 hours post infection. Together, these studies have examined the molecular response of chlamydiae to reduced iron availability and have underlined the importance for pathways involved in protection against oxidative damage and adaptation to stress

Determine the Potential Drill Utilization Improvements and Rock Fragmentation Requirements Using Directional Drilling in a Coal Mining Overburden Highwall Application

This project analyzed the efficiency of incorporating the use of directional drilling technology into coal overburden blasting. Directional drilling is currently in use in the petroleum industry and it is believed that it will be a valuable asset in the mining industry. This project has shown that directional drilling can be a viable technology for use in the coal overburden removal process resulting in increased drill utilization and potential for cost savings. Future work regarding blasting and geotechnical evaluation should be performed to solidify the concept