Letter written by Herbert E. Kaufman to Deckle Taylor, November 6, 1969

This letter discusses medical teaching and training in ophthalmology at the Duval Medical Center and other collaborations with the University Medical Center and the Duval Medical Center

Mathematical description of causative factors and prevention of elevated intraocular pressure after keratoplasty

Journal ArticleIn keratoplasty with grafts the same size as the recipient bed, tight sutures and thick recipient corneal periphery distort the angle and may collapse the filtering meshwork. This can cause very high postoperative pressures, which can be avoided by the use of donor grafts larger than the recipient bed. These relationships can be mathematically predicted

Hardware realization of real-time two-dimensional IIR filters for broadcast TV images.

In this dissertation, architectures, hardware design and prototypes for the realization of 2-D filters are presented. These filtering architectures are capable of attaining real-time processing rates for advanced television systems and are economical in terms of hardware cost, fabrication cost, and power consumption. Sample-and-hold type realizations, operating on 2-D sampled data, based on the standard 2-D discrete-time transfer function H(z\sb1,z\sb2) are presented. Both IIR and FIR realizations are developed in terms of high-speed systolic architectures. The design process culminates in the development of a 2 x 2 recursive prototype. Instead of using the standard discrete-time transfer function it is also possible to develop 2-D filters based on a 2-D hybrid transfer function H(z,s) which involves both z-domain and s-domain variables. These are highly suitable for filtering a raster scanned image, which can be characterized as an input signal X(z,s), which is a function of these same two variables. Design considerations are presented which culminate in the development of a 1 x 1 recursive prototype. The sample-and-hold systolic architecture was employed together with switched-capacitor circuit techniques to develop a 2-D real-time switched-capacitor recursive filter. This type of filter features greater accuracy than a conventional analog circuit as well as advantages for VLSI implementation. In addition to presenting novel design methodologies for hardware prototypes, a novel function block approach for the SPICE simulation of 2-D modular systems with true 2-D data is provided. This approach will serve to greatly facilitate 2-D filter development and improve the efficiency of the design cycle.Dept. of Electrical and Computer Engineering. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis1993 .K389. Source: Dissertation Abstracts International, Volume: 56-01, Section: B, page: 0423. Adviser: M. A. Sid-Ahmed. Thesis (Ph.D.)--University of Windsor (Canada), 1994

Design of a high-temperature experiment for evaluating advanced structural materials

This report describes the design of an experiment for evaluating monolithic and composite material specimens in a high-temperature environment and subject to big thermal gradients. The material specimens will be exposed to aerothermal loads that correspond to thermally similar engine operating conditions. Materials evaluated in this study were monolithic nickel alloys and silicon carbide. In addition, composites such as tungsten/copper were evaluated. A facility to provide the test environment has been assembled in the Engine Research Building at the Lewis Research Center. The test section of the facility will permit both regular and Schlieren photography, thermal imaging, and laser Doppler anemometry. The test environment will be products of hydrogen-air combustion at temperatures from about 1200 F to as high as 4000 F. The test chamber pressure will vary up to 60 psia, and the free-stream flow velocity can reach Mach 0.9. The data collected will be used to validate thermal and stress analysis models of the specimen. This process of modeling, testing, and validation is expected to yield enhancements to existing analysis tools and techniques

Increased Severity of HSV-1 Keratitis and Mortality in Mice Lacking The 2–5A-Dependent RNase L Gene

Purpose: The2′,5′-oligoadenylate-dependent RNase L gene functions in the interferon-inducible RNA decay pathway known as the 2–5A system. The purpose of this study was to determine whether the absence of this gene affects the pathogenesis of herpes simplex virus type 1 (HSV-1) ocular infection in the mouse. Methods: HSV-1 (strain McKrae) was applied bilaterally to unscarified corneas of RNase L–null mice and congenic controls. To evaluate the severity of herpetic keratitis, slit lamp examinations (SLE) were performed every other day for 14 days. To study corneal histology and apoptosis, HSV-1–inoculated RNase-L-null and congenic control mice, as well as mock-inoculated mice (apoptosis negative control), were killed at 6 and 18 hours postinoculation (PI). Uninoculated mice that underwent corneal scarification (apoptosis positive control) were killed 2 hours after scarification. Eyes were dissected and the corneas processed for light and transmission electron microscopy and the TUNEL assay. Results: In comparison with the congenic control mice, RNase L–null mice showed significantly more severe herpetic keratitis (PI day 8, SLE score, mean ± SEM: 3.27 ± 0.10 vs. 2.34 ± 0.06; P \u3c 0.001) and significantly higher mortality (PI day 14, 70% vs. 20%; P \u3c 0.001). Few apoptotic cells were seen in HSV-1–infected RNase L–null mice, although DNA fragmentation consistent with apoptosis was detected in the corneas of congenic control mice 6 and 18 hours after HSV-1 inoculation and in uninfected mice with scarified corneas. Signs of apoptosis were not present in the mock-infected corneas. Electron microscopic evidence of keratocytic apoptosis was detected only in the uninfected scarified corneas and the HSV-1–infected congenic control corneas. Conclusions: The increased severity of ocular disease and increased mortality in the RNase L–null mice provides evidence, for the first time, that the 2–5A system contributes to protection during ocular herpetic infection. The reduced frequency of apoptosis in these mice suggests that one possible mechanism for this protective effect could be the induction of apoptosis in corneal cells as a means of reducing the spread of infectious virus

Evolution on a smooth landscape

We study in detail a recently proposed simple discrete model for evolution on smooth landscapes. An asymptotic solution of this model for long times is constructed. We find that the dynamics of the population are governed by correlation functions that although being formally down by powers of $N$ (the population size) nonetheless control the evolution process after a very short transient. The long-time behavior can be found analytically since only one of these higher-order correlators (the two-point function) is relevant. We compare and contrast the exact findings derived herein with a previously proposed phenomenological treatment employing mean field theory supplemented with a cutoff at small population density. Finally, we relate our results to the recently studied case of mutation on a totally flat landscape.Comment: Revtex, 15 pages, + 4 embedded PS figure

The Impossibility of a Perfectly Competitive Labor Market

Using the institutional theory of transaction cost, I demonstrate that the assumptions of the competitive labor market model are internally contradictory and lead to the conclusion that on purely theoretical grounds a perfectly competitive labor market is a logical impossibility. By extension, the familiar diagram of wage determination by supply and demand is also a logical impossibility and the neoclassical labor demand curve is not a well-defined construct. The reason is that the perfectly competitive market model presumes zero transaction cost and with zero transaction cost all labor is hired as independent contractors, implying multi-person firms, the employment relationship, and labor market disappear. With positive transaction cost, on the other hand, employment contracts are incomplete and the labor supply curve to the firm is upward sloping, again causing the labor demand curve to be ill-defined. As a result, theory suggests that wage rates are always and everywhere an amalgam of an administered and bargained price. Working Paper 06-0

Corneal Healing after Uncomplicated LASIK and Its Relationship to Refractive Changes: A Six-Month Prospective Confocal Study

PURPOSE. To investigate corneal healing and the factor(s) possibly responsible for refractive changes after laser in situ keratomileusis (LASIK). METHODS. Twenty eyes of 10 patients who underwent LASIK for myopia were examined clinically and by real-time confocal microscopy for 6 months. Epithelial and posterior stromal thicknesses and the thickness of the keratocyte activation zone were measured, and refractive changes were compared with these values. Keratocyte morphology, flap thickness, and subbasal nerve fiber bundle morphology after LASIK were also investigated. RESULTS. No significant change was detected over time in epithelial thickness after LASIK treatment; however, the posterior stromal thickness was found to be significantly higher 1 month after surgery. A slight but statistically significant negative correlation was detected between the thickness of the keratocyte activation zone and the spheroequivalent refraction after LASIK. The subbasal nerve fiber bundle's morphology returned to its preoperative appearance 6 months after LASIK, but in the flap stroma the nerve fiber bundle morphology remained abnormal at 6 months after LASIK surgery. CONCLUSIONS. A weak but significant negative correlation between the thickness of the keratocyte activation zone and spheroequivalent refraction was found after LASIK. The different refractive properties of activated keratocytes may be responsible for the myopic shift after LASIK. Further studies are needed to clarify this hypothesis. (Invest Ophthalmol Vis Sci. 2004;45:1334 -1339) DOI:10.1167/iovs.03-1025 L aser in situ keratomileusis (LASIK) is a relatively new technique for correction of myopia. A hinged flap (consisting of epithelium, Bowman's layer, and anterior stroma) is created first, and the exposed stroma is photoablated after the flap is folded back. Although many studies have been published on the clinical outcome after LASIK, 1-4 relatively few reports address the biological changes associated with the procedure. 10,11 Keratocyte activation was strongest at 1 to 2 weeks and persisted until 3 months after LASIK surgery. 10,13 Neither LASIK nor PRK has been shown superior in efficacy outcomes 14 -16 A recent confocal microscopic study revealed that keratocyte-mediated regrowth of the photoablated stroma was a key biological factor responsible for post-PRK refractive instability in humans treated with PRK. The purpose of this study was to investigate the factor(s) responsible for the refractive changes after LASIK. For this purpose, epithelial thickness, posterior stromal thickness, and the thickness of the keratocyte activation zone were measured by confocal microscopy, and we sought to establish a correlation between refractive changes and these measurements. We also investigated keratocyte morphology, flap thickness, and subbasal nerve fiber bundle morphology after LASIK. METHODS Design This prospective, interventional cohort study was begun after approval was obtained from the LSU Health Sciences Center institutional review board. Each patient gave written informed consent, and the research followed the tenets of the Declaration of Helsinki. Patients Twenty eyes of 10 patients who underwent LASIK for myopia were included in the study. All eyes had normal anterior ocular segments, intraocular pressure (Ͻ20 mm Hg), and fundi. Contact lens wear was discontinued 2 weeks (soft lenses) or 3 weeks (hard lenses) before the LASIK operation. There were six women and four men (mean age, 35.4 Ϯ 8.7 years). All patients were 21years of age or older and had stable refractive errors at least 1 year before the laser procedure. Patients who had undergone reoperation, those with diabetes mellitus or glaucoma, or those using any topical ophthalmic medication were excluded. Patients with corneas thinner than 500 m centrally and/or with a severe systemic disorder that could cause them to miss examinations were also excluded. The average preoperative spheroequivalent refraction was Ϫ5.87 Ϯ 3.45 D (range, Ϫ1.75-11.00 D) and the planned ablation depth was 59.8 Ϯ 27.1 m (range, 16 -110 m). Each patient was examined in the pre-and postoperative period. Preoperative examinaFrom th