Thesis (Ph.D.)--Boston University / PLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you. / The present stuqy is an investigation of the effects of two parameters of the spiral aftereffect. Clinical psychologists have been interested in aftereffect research because of the possibility of utilizing the phenomenon as a diagnostic tool for brain damage. The parameters which were studied are frequoocy of stmulation (FS) and boundary velocity (BV). Frequency of stimulation is the frequency with which a given retinal element is stimulated by a contour (boundary) of the moving stimulus. The frequency of stimulation for the spiral is defined as the product of number of spiral arms and rotational velocity. In this study, variations in frequenqy of stimulation were effected by varying the number of spiral arms. Boundary velocity is the velocity with which a given contour (boundary) passes across a retinal element. In the spiral, boundary velocity corresponds to the rate of expansion or contraction, and it is proportional to: [(Rotational Velocity) x (Visual Angle Subtended by Spiral)]/(Number of Spiral Turns) Variations in boundary velocity were effected by simultaneously varying number of spiral arms and rotational velocity in such a way that frequency of stimulation remained constant and boundary velocity varied. In this study, a population of responses was sampled from two male subjects, each of Whom viewed five Archimedes spirals rotated at four rotational velocities. The spirals were drawn with one, two, four, eight, and sixteen arms, and were rotated at 40 rpm, 80 rpm, 160 rpn, and (all except the sixteen arm spiral) at 320 rpm. Each spiral-speed combination was repeated three times each day for eight days, resulting in a total of 24 replications for each spiral-speed combination. The dependent variable was the aftereffect, as measured by extent and duration. [TRUNCATED] / 2999-01-01

Optical imaging polarimetry has been performed on seven nearby Seyfert galaxies, three with face-on and four with edge-on host galaxies of various morphological classifications. Observations in V, R, B and H(_a) wavebands are presented as maps of total intensity and of polarized intensity, overlaid with polarization vectors. Independent determinations of the interstellar polarization (ISP) contribution from our own galaxy are made where possible, and are used to produce ISP corrected maps. The polarization patterns seen in the maps show evidence of either dichroic extinction, which indicates the presence of non-spherical dust grains in large-scale galactic magnetic fields, or scattering, which is due to the illumination of regions of dust grains or electrons. The polarization features, which are observed at the different wavebands, are then compared to recent models of polarization in external galaxies. Estimates of the intrinsic Seyfert nuclear polarization are made where possible by correcting for ISP and for an approximation of the dilution due to the host galaxy flux by using values from previous studies. Both the measured and the corrected nuclear polarizations are compared with previously published values, and are discussed in the context of the standard models of Seyfert galaxies. Most of the observed galaxies show evidence of polarization, both from the host galaxy and from the intrinsic Seyfert nucleus. In particular, distinct polarization features: bands of polarization consistent with extended dusty disks aligned with the dusty tori proposed in Seyferts, and regions of polarization corresponding to scattering of the nuclear continuum along the biconical extended Seyfert emission-line regions, have been identified in several of the observed galaxies.

The objective of this dissertation is twofold. Firstly an extensive yet concise literature review on the state-of-the-art of near infrared barred spiral galaxy classi cation is presented. Secondly, two quantitative approaches to galaxy classi cation at near infrared wavelengths, the relative gravitational torque method and the isophotal ellipse tting method, are applied for the rst time to a sample of selected Spitzer IRAC nearby barred galaxies. Maximum relative gravitational torques are derived for a sample of 40 nearby bright barred disk galaxies at 3.6 m and 4.5 m. These torques are compared between galaxy pairs at these passbands and we nd an excellent agreement between the 3.6 m and 4.5 m morphology. The sample used incorporates a wide range of inclination and bar strength values. The tight coupling of 3.6 m and 4.5 m morphology provides an opportunity to classify intermediate redshift galaxies that have their near-infrared rest frame emissions shifted red-ward to 4.5 m; i.e.: out to z = 0:25. We nd a greater frequency of higher maximum relative torques in our sample compared with either Block et al. (2002) or Buta et al. (2004) due to sample bias, as this dissertation is aimed at understanding quantitative methods in classifying barred galaxies. Furthermore, we compare results from applying an isophotal ellipse tting technique and a gravitational torque analysis to a common sample of 28 nearby barred S4G/Spitzer galaxies imaged at 3.6 m. These two quantitative bar strength methods are applied to images that have identical orientation and deprojection parameters for an objective comparison. We nd a strong correlation between the gravitational torque and isophotal ellipse tting methods which in principle supports a method for estimating bar potentials out to intermediate redshifts by using an isophotal ellipse tting approach. This has important implications for bar-fraction estimates and galaxy accretion/evolution scenarios.

Dans cette thèse nous avons éffectué l'analyse des données relatives à l'expérience réalisée au GANIL pour laquelle un faisceau de (^11)Be a bombardé une cible de (^48)Ti dans le but d'étudier la réaction (^48]Ti((^11)Be,(^10)Be+n+gamma) à 41 MeV/nucléon. L'utilisation du towing mode dans l'étude des noyaux a montré sa potentialité pour la détermination de facteurs spectroscopiques à l'aide du calcul TDSE. De nouveaux développements devraient nous permettre d'approfondir nos connaissances sur les noyaux exotiques avec, dans un avenir proche, le projet SPIRAL II extension du projet SPIRAL au GANIL. Ce projet fournira des faisceaux radioactifs plus lourds que ceux étudiés actuellement grâce à la fission de noyau d'uranium induite par un faisceau de deutons de très haute intensité.

Thesis (M.S. in Engineering Science (Electrical Engineering))--Naval Postgraduate School, December 2003. / Thesis advisor(s): David Jenn, Jeffrey B. Knorr. Includes bibliographical references (p. 73-76). Also available online.

The north and south polar layered deposits (NPLD and SPLD respectively) of Mars are 2 – 3 km thick and mostly ice, comprising nearly all of the known water reserves on Mars. They are commonly believed to hold a detailed record of recent (~10 – 100 Myr) climate within their layers. Dominating the surface of the NPLD, intriguing spiral depressions called troughs, exhibit a pinwheel appearance. In late 2006, the Shallow Radar (SHARAD) instrument began making observations. SHARAD can detect internal structure within the PLD, making observations that are impossible with instruments that only inspect the surface. SHARAD data reveals a unique stratigraphic record associated with trough formation and migration. The troughs did not exist during deposition of the first half of NPLD accumulation but initiated some 1000 m below the current surface and have migrated as much as 100 km northward. Three processes are responsible for this migration: wind transport, insolation induced sublimation, and atmospheric deposition. I synthesize work from ground penetrating radar, optical imagery, established analogs, and atmospheric modeling in order to derive a process model that describes trough formation and evolution, including migration. The NPLD spiral troughs belong to a larger classification of features called cyclic steps, which can exist in either erosional or depositional environments. On the SPLD, troughs and a variety of other features exist. While SPLD features are more complex than NPLD troughs, they exist due to the same three processes. / text

国立情報学研究所で電子化したコンテンツを使用している。

Thesis (Ph.D.)--McMaster University, 2005. / Supervisor: W.E. Harris. Includes bibliographical references (p. 127-132).

Thesis (Ph. D.)--Ohio State University, 2004. / Title from first page of PDF file. Document formatted into pages; contains xiv, 86 p.; also includes graphics. Includes bibliographical references (p. 83-86).

Tübingen, Univ., Diss., 2005.