David Lerner

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The paths of 15 micron diameter laser beams traversing goldfish eye lenses were photographed. Measurements of these photographs gave experimental data for the distance of the exit point of each ray from the lens axis as a function of the corresponding entrance distance. A number of mathematical models with distinct distributions of refractive index within(More)
A gene coding for a small heat shock protein homolog from the hyperthermophilic methanogenic Archaeon Methanococcus jannaschii was cloned. This gene was overexpressed in Escherichia coli harboring rare codon tRNAs and its protein purified and crystallized. Crystals displayed the space group R3 with unit cell dimensions a = b = 171.46 A and c = 102.13 A in a(More)
In the analysis of chaotic time series, a standard technique is to reconstruct an image of the original dynamical system using delay coordinates. If the original dynamical system has an attractor, then the correlation dimension D2 of its image in the reconstruction can be estimated using the Grassberger–Procaccia algorithm. The quality of the reconstruction(More)
Systems of coupled chaotic maps and flows arise in many situations of physical and biological interest. The aim of this paper is to analyze and to present numerical evidence for a common type of nonhyperbolic behavior in these systems: unstable dimension variability. We show that unstable periodic orbits embedded in the dynamical invariant set of such a(More)
A new method is developed to construct a cochlear transducer function using modulation of the summating potential (SP), a dc component of the electrical response of the cochlea to a sinusoid. It is mathematically shown that the magnitude of the SP is determined by the even-order terms of the power series representing a nonlinear function. The relationship(More)
A new method for studying leakage of root fillings using the bacterium Pseudomonas fluorescens ATCC 13525 is described. The presence of the microorganism is detected by fluorimetry and can thus be used to measure the depth of penetration from the root apex toward the crown of the tooth. This system, applied to a number of methods of root canal filling,(More)
The baking expansion properties of sour cassava starch (Polvilho azedo) are attributable to photochemical starch degradation induced by heterolactic fermentation after sun-drying. This study investigated the effects of UV irradiation on the different structural levels of cassava starch as compared to those of corn starch and dextrins. Photosensitive(More)
In the UK, the recycling of sewage sludge to land is expected to double by 2006 but the security of this route is threatened by environmental concerns and health scares. Strategic investment is needed to ensure sustainable and secure sludge recycling outlets. At present, the security of this landbank for sludge recycling is determined by legislation(More)
Mutation rate balances the need to protect genome integrity with the advantage of evolutionary innovations. Microorganisms increase their mutation rate when stressed, perhaps addressing the growing need for evolutionary innovation. Such a strategy, however, is only beneficial under moderate stresses that allow cells to divide and realize their mutagenic(More)
Automated seizure detection with high specificity and sensitivity is a highly desirable but elusive goal. The failure to develop a reliable system despite decades of effort is due in part to the non-stationary and noise in the EEG/ECoG signals, as well as to the rudimentary mathematical treatment it has received. Another important limitation of present(More)