Chromosomal Deficiencies and the Embryonic Development of Drosophila Melanogaster

Chromosome aberrations have marked effects upon the development of an organism. Many such aberrations are lethal. In Drosophila this is particularly true of chromosomal deficiencies, as first described by Bridges [2]. A more detailed study of the effects of such aberrations made by Li [3] shows that in all the cases he investigated deficiencies are lethal in the homozygous condition the organisms dying in the egg or larval stages. Heterozygous deficiencies result in death in later stages, although many are not lethal. A few exceptional cases of viable homozygous deficiencies have been described [4,5]. In such instances the deficiencies are among the smallest known, probably for very few genes. These facts emphasize the importance of the chromosomes in the developmental processes. Just what the chromosomal functions may be, however, is by no means clear; nor is the role of the individual gene evident. An ideal approach, such as the removal of one gene at a time, then of combinations of genes, to determine the part played by each and its interactions with others, presents many practical difficulties. The existence of numerous deficiencies, however, makes an approximation to this approach possible by the study of the effects of larger or smaller blocks of genes. The present study is concerned with the effects of certain deficiencies upon the embryonic development of D. melanogaster. The deficiencies used involved greater or lesser portions of the X-chromosome, ranging from the total absence of the X to a small deficiency involving relatively few "bands" as seen in the salivary gland chromosome. The technique of Huettner and Rabinowitz [6] was used, in a somewhat modified form, for the observation of living eggs, and details of internal structure were studied by means of sectioned material. Only timed eggs were used. Usually females were allowed to lay for half an hour and the eggs allowed to develop to the desired stage at a temperature of 22-23°C

Arriving at the surface: an analysis of the organisation of the surface of paintings and the space around them as sites to generate specific practices of thought

This research project presents a number of approaches towards the surfaces produced within my own practice. In this sense it is a reversed critique, a meditation upon the practice of considering artworks shaped by the structures of the works themselves, rather than an attempt to align the works with other existing external structures of explanation. The surface of the picture plane presents the researcher with grave difficulties. It is silent and fixed, and necessarily complete unto itself. It has a defined border that divides it from the flux of the world around it. Meditation upon such a site would seem to produce only a stream of interpretive reflection. Without the precise definitions of language, images might only appear to offer the opportunity for highly subjective responses, becoming material for textual metaphor. This approach overlooks the possibility that the site of the painting does not just represent ideas, but actually can be an apparatus to generate and contain thought. The ‘surface’ becomes not the hard unyielding face of the image, but a shifting border that must account for the movements of time and the mechanisms of perception. The surface is an object, and a series of events collapsed into this object. To explore this possible ‘event’ in my own practice I undertook the exploration a number of different forms of organising and presenting works, combined with simultaneous investigations into other artist’s work and methods. This mimics the way in which I construct my own work; allowing a group of image/ideas to coalesce around a projected ‘surface’, which here would be a defined space of production (a canvas, a exhibition space, a live performance). The danger of this approach is that the clumps of thought/image will remain singular and disconnected, and the surface will not exist as anything more than a collection of things. For the works to succeed as sites to generate specific thought they must also reveal some kind of method of investigation to the viewer. This project examines some particular instances where such methodologies can be seen in operation

A parallel butterfly algorithm

The butterfly algorithm is a fast algorithm which approximately evaluates a discrete analogue of the integral transform \int K(x,y) g(y) dy at large numbers of target points when the kernel, K(x,y), is approximately low-rank when restricted to subdomains satisfying a certain simple geometric condition. In d dimensions with O(N^d) quasi-uniformly distributed source and target points, when each appropriate submatrix of K is approximately rank-r, the running time of the algorithm is at most O(r^2 N^d log N). A parallelization of the butterfly algorithm is introduced which, assuming a message latency of \alpha and per-process inverse bandwidth of \beta, executes in at most O(r^2 N^d/p log N + \beta r N^d/p + \alpha)log p) time using p processes. This parallel algorithm was then instantiated in the form of the open-source DistButterfly library for the special case where K(x,y)=exp(i \Phi(x,y)), where \Phi(x,y) is a black-box, sufficiently smooth, real-valued phase function. Experiments on Blue Gene/Q demonstrate impressive strong-scaling results for important classes of phase functions. Using quasi-uniform sources, hyperbolic Radon transforms and an analogue of a 3D generalized Radon transform were respectively observed to strong-scale from 1-node/16-cores up to 1024-nodes/16,384-cores with greater than 90% and 82% efficiency, respectively.Comment: To appear in SIAM Journal on Scientific Computin

Pediatric Sleep Questionnaire Used to Assess Sleep-Related Breathing Disorders in a Western Pennsylvania Private Orthodontic Practice

Sleep related breathing disorders (SRBD) in children have a reported prevalence of 4-11% and manifest as behavioral, physical, and/or academic deficiencies. SRBD in children include snoring, obstructive sleep apnea (OSA), and hypopnea. Unlike adults, OSA incidence in pediatric patients occurs equally in males and females, with the greatest incidence from ages 2-8 years old. The greater incidence during this age range is primarily due to larger pharyngeal lymphatic tissues, which regress as the patient progresses into adolescence. After puberty, the prevalence of OSA increases more in boys than girls, which could be due to testosterone-induced changes. The gold standard for measuring SRBD is an overnight polysomnograph, which is burdensome to both the patient and the parent. For this reason, numerous questionnaires have been created to help identify patients at risk for SRBD. The Pediatric Sleep Questionnaire (PSQ) is a 22-point questionnaire which can be scored quickly and easily. When more than one third of the answers are answered positively, there is an increased likelihood that the patient would have positive signs of SRBD on a polysomnograph. With a specificity of 81% and a sensitivity of 85%, the questionnaire is a powerful tool for identifying patients who may be at a higher risk for SRBD. By looking at 1500 consecutive PSQ given to all patients under the age of 18 as part of the routine medical history, the prevalence of SRDB in pediatric orthodontic patients in a private practice in Western Pennsylvania will be estimated in an effort to describe how common this disorder may be in a common orthodontic environment