Ian Young - Academia.edu (original) (raw)

Papers by Ian Young

Human Vision and Electronic Imaging IV, 1999

ABSTRACT We present the results of experiments in which we investigate how the physical gamma map... more ABSTRACT We present the results of experiments in which we investigate how the physical gamma maps onto the perceived gamma, and how the subjective quality of a printed image may be influenced by the grey scale mapping that is used to print the image. The grey scale is altered by changing the gamma, the exponent relating the input to the output luminance. Five natural images, widely different in content, have been printed with 16 different values of gamma. First the printer gamma is measured. In general, this gamma differs from 1. In the printer a gamma transform is performed as well. The selected gamma values are corrected using the directly gamma function. The aim of the first experiment is to find out what the relation is between physical gamma and perceived gamma. The stimulus response function derived from our data is found to be quite linear over the range investigated. The aim of the second experiment is to test the subjective preference for a particular gamma. We have found that these gammas are not independent of image content. The mean preference averaged over the subjects for the various images ranges form 1.6 to 2.2.

Bioimaging, 1998

Abstract. In this note we will present methods based on image processing techniques to evaluate t... more Abstract. In this note we will present methods based on image processing techniques to evaluate the performance of light microscopes. These procedures are applied to three different `high-end&amp;amp;amp;amp;amp;amp;#x27;light microscopes. Tests are carried out to measure the homogeneity of the illumination system. From these tests it follows that K篓ohler illuminated images can have an exceedingly high amount of shading. Another result

Cell and Tissue Biology, 2008

ABSTRACT

Optical Materials, 2009

We report on the structural and optical properties of self-ordered nanoporous anodic alumina (NAA... more We report on the structural and optical properties of self-ordered nanoporous anodic alumina (NAA) films annealed at different temperatures. The morphology of NAA films is examined by scanning electron microscopy (SEM). The results show that the porous structure have hexagonally ordered arrays of nanopores with interpore distance in the range of 90-100 nm and pore size between 30 and 40 nm. The structural properties studied by X-ray diffraction (XRD) show out that the nanoporous alumina experiences a transition from the amorphous phase to gamma and alpha phase when annealed from 800 to 1200°C. The optical transmission spectra of the annealed NAA films with different thicknesses (9, 24 and 45 lm) are measured in the wavelength range of 300-1000 nm. Numerical simulations based on an optical model of the films show a good agreement with the measurements. The refractive index (n) and the extinction coefficient (k) are determined for each annealed temperature.

We calculated the field pattern above hole-arrays with an analytical model that we developed. Spe... more We calculated the field pattern above hole-arrays with an analytical model that we developed. Spectral imaging measurements strongly confirm the model. Such a pattern can be used for high resolution fluorescence measurements of biological samples.

Plasmonics in Biology and Medicine, 2004

Recently, an extraordinary transmission of light through small holes (<200 nm) in a thin metallic... more Recently, an extraordinary transmission of light through small holes (<200 nm) in a thin metallic film has been described. This phenomenon has been shown to be the result of the photon-plasmon interaction in thin films where a periodic structure (such as a set of holes) is embedded in the film. One of the extraordinary results is that the beam that passes through a hole has a very small diffraction in extreme contrast to the wide angle predicted by diffraction theory.

Nature methods, Jan 18, 2016

We developed single-image fluorescence lifetime imaging microscopy (siFLIM), a method for acquiri... more We developed single-image fluorescence lifetime imaging microscopy (siFLIM), a method for acquiring quantitative lifetime images from a single exposure. siFLIM takes advantage of a new generation of dedicated cameras that simultaneously record two 180°-phase-shifted images, and it allows for video-rate lifetime imaging with minimal phototoxicity and bleaching. siFLIM is also inherently immune to artifacts stemming from rapid cellular movements and signal transients.

Biomicrofluidics, 2008

In this paper, we demonstrate for the first time that insulative dielectrophoresis can induce siz... more In this paper, we demonstrate for the first time that insulative dielectrophoresis can induce size-dependent trajectories of DNA macromolecules. We experimentally use ͑48.5 kbp͒ and T4GT7 ͑165.6 kbp͒ DNA molecules flowing continuously around a sharp corner inside fluidic channels with a depth of 0.4 m. Numerical simulation of the electrokinetic force distribution inside the channels is in qualitative agreement with our experimentally observed trajectories. We discuss a possible physical mechanism for the DNA polarization and dielectrophoresis inside confining channels, based on the observed dielectrophoresis responses due to different DNA sizes and various electric fields applied between the inlet and the outlet. The proposed physical mechanism indicates that further extensive investigations, both theoretically and experimentally, would be very useful to better elucidate the forces involved at DNA dielectrophoresis. When applied for size-based sorting of DNA molecules, our sorting method offers two major advantages compared to earlier attempts with insulative dielectrophoresis: Its continuous operation allows for highthroughput analysis, and it only requires electric field strengths as low as ϳ10 V / cm.

Cytometry Part A, 2011

Chromosome positions within the nucleus of mammalian cells are nonrandom and it is assumed that c... more Chromosome positions within the nucleus of mammalian cells are nonrandom and it is assumed that chromosomal neighborhoods affect the probability of translocations. Four chromosomes can be involved in c-myc-activating chromosomal translocations in mouse plasmacytoma (PCT): the c-myc gene on mouse chromosome 15 can be juxtaposed to either one of the immunoglobulin (Ig) loci on chromosomes 12 (IgH), 16 (Igk), or 6 (Igj). In the BALB/c mouse, the translocation between chromosomes 12 and 15, T(12;15), is most common (90%) while the other two possible translocations, T(6;15) and T(16;15), are much less common (\10%). In contrast, in the BALB/ cRb6.15 mouse, T(6;15) is found with the same frequency as T(12;15). We, therefore, examined the distance between chromosomes 15 and 12, 6, and 16 in primary mouse B lymphocytes in order to examine the effect of the chromosome proximity on the translocation frequency. We performed three-dimensional fluorescent in situ hybridization (3D-FISH) with chromosome paints. We acquired three-dimensional image stacks with 90 slices per stack and used constrained iterative deconvolution. The nucleus and chromosomes were segmented from this image stack and the interchromosomal distances were measured. Chromosomes 6 and 15 were found in close proximity in BALB/ cRb6.15 mice (82%), whereas they did not share this neighborhood relationship in BALB/c mice. No other chromosome combinations showed such a high percentage of close proximities in either mouse strain. Chromosome positions contribute to translocation frequencies in mouse PCTs. The BALB/cRb6.15 mouse data argue for a proximity relationship of chromosomes that engage in illegitimate recombination. These positions are not, however, the only contributing factor as the T(12;15) translocation preference in BALB/c mice could not be supported by significantly elevated proximity of chromosomes 12 and 15 versus 12 and 16 or 12 and 6. Moreover, while there is a significant increase in T(6;15) in BALB/cRb6.15 mice, T(12;15) still occurs in this mouse strain. ' 2011 International Society for Advancement of Cytometry

Automation of Cytogenetics, 1989

In this article we describe a system we have constructed that provides for automated karyotyping ... more In this article we describe a system we have constructed that provides for automated karyotyping of metaphase spreads. The software system Athenabased upon the Macintosh II computer and a Data Translation's frame grabber -is written entirely in C and consists of approximately 200 Kbytes of executable code. While Athena does not provide (at this time) facilities for automated metaphase finding, it does provide facilities for automated image segmentation into individual chromosomes, automated measurements on each banded chromosome, and automated classification into the standard Paris-convention karyotype. Further, the system provides the ability to construct one or more chromosome data bases to represent the types of metaphase spreads and staining techniques that may be used in a given laboratory.