Senior Recital

List of performers and performances

Incomitance in Monkeys with Strabismus

Purpose: Rhesus monkeys reared with restricted visual environment during their first few months of life develop large ocular misalignment (strabismus). The purpose of this study was to describe ‘A and V’ patterns and DVD in these animals during fixation and eye movements and suggest that this form of rearing produces animals that are a suitable model to study mechanisms that might cause ‘A/V’ pattern incomitant strabismus and dissociated vertical deviation (DVD) in humans. Methods: Eye movements were recorded during fixation, smooth-pursuit and saccades using binocular search coils in one monkey with esotropia, three monkeys with exotropia and one normal monkey. Results: 1) Monkeys reared with Alternating Monocular Occlusion or Binocular deprivation (tarsal plates intact) showed both horizontal and vertical misalignment during monocular and binocular viewing. 2) Large ‘A’ patterns were evident in 2 out of 3 exotropes while a ‘V’ pattern was observed in the esotrope. 3) Similar ‘A/V’ patterns were observed with either eye viewing and during fixation or eye movements. 4) The vertical misalignment, which consisted of the non-viewing eye being higher than the fixating eye, appeared to constitute a DVD. Conclusion: Visual sensory deprivation methods that induce large strabismus also induce ‘A/V’ patterns and DVD similar to certain types of human strabismus. The source of the pattern strabismus could be central, i.e., altered innervation to extraocular muscles from motor nuclei, or peripheral, i.e., altered location of extraocular muscle pulleys

Horizontal Saccade Disconjugacy in Strabismic Monkeys

Purpose: Previous studies have shown that binocular coordination during saccadic eye movement is affected in humans with large strabismus. The purpose of this study was to examine the conjugacy of saccadic eye movements in monkeys with sensory strabismus. Maethods: The authors recorded binocular eye movements in four strabismic monkeys and one unaffected monkey. Strabismus was induced by first occluding one eye for 24 hours, switching the occluder to the fellow eye for the next 24 hours, and repeating this pattern of daily alternating monocular occlusion for the first 4 to 6 months of life. Horizontal saccades were measured during monocular viewing when the animals were 2 to 3 years of age. Results: Horizontal saccade testing during monocular viewing showed that the amplitude of saccades in the nonviewing eye was usually different from that in the viewing eye (saccade disconjugacy). The amount of saccade disconjugacy varied among animals as a function of the degree of ocular misalignment as measured in primary gaze. Saccade disconjugacy also increased with eccentric orbital positions of the nonviewing eye. If the saccade disconjugacy was large, there was an immediate postsaccadic drift for less than 200 ms. The control animal showed none of these effects. Conclusions: As do humans with large strabismus, strabismic monkey display disconjugate saccadic eye movements. Saccade disconjugacy varies with orbital position and increases as a function of ocular misalignment as measured in primary gaze. This type of sensory-induced strabismus serves as a useful animal model to investigate the neural or mechanical factors responsible for saccade disconjugacy observed in humans with strabismus

Conjugate Adaptation of Saccadic Gain in Non-Human Primates With Strabismus

In this study, we have used the double-step paradigm to test saccadic gain adaptation during monocular viewing in one normal monkey, two monkeys with exotropia, and one monkey with esotropia. In this paradigm, the target for the saccade is displaced during the saccade, resulting in a consistent visual error. Studies in normal humans and monkeys have shown that the brain responds to this consistent visual error by gradually changing saccade gain. Using this technique, we were able to elicit adaptation in both the viewing eye and the nonviewing eye in the normal monkey and in monkeys with strabismus. The rate of adaptation was not significantly different in the viewing and nonviewing eyes in the normal and strabismic monkeys. The magnitude of adaptation as calculated by a percentage change in gain was also not significantly different in the viewing and the nonviewing eyes in the normal and strabismic monkeys. Our data show that animals with strabismus retain the ability to elicit a conjugate adaptation of saccades using this mechanism. We also suggest that the double-step paradigm elicits a conjugate adaptation of saccades whether the animal is viewing monocularly (our studies) or binocularly (data published in literature)

The correlation between market fundamentals and apartment REIT performance

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Urban Studies and Planning, 2001."September 2001."Includes bibliographical references (leaves 64-66).This paper empirically examines the correlation between apartment REIT performance (as measured by Funds from Operations, Net Operating Income, Gross Rental Revenue, Net Income, Market Capitalization and CAP Rate) and market fundamentals (as measured by weighted average rent growth, weighted average employment growth, weighted average stock growth and weighted average excess demand). The objective of this paper is to explain the variance in historical apartment REIT performance based on historical market fundamentals. Market fundamentals are broadly defined as the employment growth, population growth, stock growth and rent growth. More detailed definitions of market fundamentals are provided within the paper. Independent variables are developed from market data collected from 57 MSAs. Using these data, weighted averages are generated in order to isolate geographical effects. These independent variables are regressed against measures of financial performance of apartment REITs as of December 31, 2000. The results show that weighted average rent growth (given NREI rent data) and growth in apartment units explain 37.1% of the variance in the percent change in FFO per unit and 37.8% of the variance in the percent change in market capitalization per unit across the sample of selected apartment REITs. Furthermore, weighted average rent growth (given government rent data) does a relatively poor job of explaining the variance in the percent change in FFO per unit.by Andrew A. Friestedt and Brina J. Tusa.S.M

Cervico-Ocular Reflex in Normal Subjects and Patients with Unilateral Vestibular Hypofunction

Objective: To determine whether the cervico-ocular reflex contributes to gaze stability in patients with unilateral vestibular hypofunction. Study Design: Prospective study. Setting: Tertiary referral center. Patients: Patients with unilateral vestibular hypofunction (n = 3) before and after vestibular rehabilitation and healthy subjects (n = 7). Interventions: Vestibular rehabilitation. Main Outcome Measures: We measured the cervico-ocular reflex in patients with unilateral vestibular hypofunction before and after vestibular rehabilitation and in healthy subjects. To measure the cervico-ocular reflex, we recorded eye movements with a scleral search coil while the trunk moved at 0.3, 1.0, and 1.5 Hz beneath a stabilized head. To determine whether the head was truly stabilized, we measured head movement using a search coil. Results: We found no evidence of cervico-ocular reflex in any of the seven healthy subjects or in two of the patients with unilateral vestibular hypofunction. In one patient with chronic unilateral vestibular hypofunction, the cervico-ocular reflex was present before vestibular rehabilitation only for leftward trunk rotation (relative head rotation toward the intact side). After 5 weeks of placebo exercises, there was no change in the cervico-ocular reflex. After an additional 5 weeks that included vestibular exercises, cervico-ocular reflex gain for leftward trunk rotation had increased threefold. In addition, there was now evidence of a cervico-ocular reflex for rightward trunk rotation, potentially compensating for the vestibular deficit. Conclusion: The cervico-ocular reflex appears to be a highly inconsistent mechanism. The change of the cervico-ocular reflex in one patient after vestibular exercises suggests that the cervico-ocular reflex may be adaptable in some patients

Rethinking the social impacts of the arts

The paper presents a critical discussion of the current debate over the social impacts of the arts in the UK. It argues that the accepted understanding of the terms of the debate is rooted in a number of assumptions and beliefs that are rarely questioned. The paper goes on to present the interim findings of a three‐year research project, which aims to rethink the social impact of the arts, with a view to determining how these impacts might be better understood. The desirability of a historical approach is articulated, and a classification of the claims made within the Western intellectual tradition for what the arts “do” to people is presented and discussed

A Prototype Head-Motion Monitoring System for In-Home Vestibular Rehabilitation Therapy

This work reports the use of a head-motion monitoring system to record patient head movements while completing in-home exercises for vestibular rehabilitation therapy. Based upon a dual-axis gyroscope (yaw and pitch, ± 500-degrees/sec maximum), angular head rotations were measured and stored via an on-board memory card. The system enabled the clinician to document exercises at home. Several measurements were recorded in one patient with unilateral vestibular hypofunction: The total time of exercise for the week (118 minutes) was documented and compared with expected weekly exercise time (140 minutes). For gaze stabilization exercises, execution time of 60 sec was expected, and observed times ranged from 75-100 sec. An absence of rest periods between each exercise instead of the recommended one minute rest period was observed. Maximum yaw head velocities from approximately 100-350 degrees/sec were detected. A second subject provided feedback concerning the ease of use of the HAMMS device. This pilot study demonstrates, for the first time, the capability to capture the head-motion “signature” of a patient while completing vestibular rehabilitation exercises in the home and to extract exercise regime parameters and monitor patient adherence. This emerging technology has the potential to greatly improve rehabilitation outcomes for individuals completing in-home gaze stabilization exercises 1

Oculomotor Strategies and Their Effect on Reducing Gaze Position Error

Objective: Vestibular adaptation exercises have been shown to improve gaze stability during active head rotation in individuals with vestibular hypofunction. Little is known, however, of the types of eye movements used during passive head rotation and their effect on gaze stability in individuals with vestibular hypofunction. The primary purpose of this study was to determine differences in oculomotor strategies and their effect on stabilizing gaze during ipsilesional passive and active head rotations in vestibular hypofunction. Patients: Subjects with unilateral (n = 4) and bilateral (n = 3) vestibular hypofunction and healthy subjects (n = 4) based on bithermal caloric and rotational chair testing. Intervention: Diagnostic. Main Outcome Measure: Head and eye velocity and position data measured with scleral search coil. Results: Subjects with unilateral and bilateral vestibular hypofunction generated 3 types of gaze-stabilizing eye movements with ipsilesional head impulses: slow vestibular ocular reflex, compensatory, and corrective saccades. The types of eye movements generated during active and passive head impulses were highly individualized. Gaze position error was reduced when compensatory saccades were recruited as part of the gaze-stabilizing strategy. Conclusion: Rehabilitation for individuals with vestibular hypofunction should identify individuals' unique gaze stability preferences and attempt to facilitate compensatory saccades

Effect of the Orbital Level Difference in Doped Spin-1 Chains

Doping of a two-orbital chain with mobile S=1/2 Fermions and strong Hund's rule couplings stabilizing the S=1 spins strongly depends on the presence of a level difference among these orbitals. By DMRG methods we find a finite spin gap upon doping and dominant pairing correlations without level-difference, whereas the presence of a level difference leads to dominant charge density wave (CDW) correlations with gapless spin-excitations. The string correlation function also shows qualitative differences between the two models.Comment: 4 pages, 4 figure