Technology: Servant or Master of the Online Teacher?

published or submitted for publicatio

A Kosloff/Basal method, 3D migration program implemented on the CYBER 205 supercomputer

Conventional finite difference migration has relied on approximations to the acoustic wave equation which allow energy to propagate only downwards. Although generally reliable, such approaches usually do not yield an accurate migration for geological structures with strong lateral velocity variations or with steeply dipping reflectors. An earlier study by D. Kosloff and E. Baysal (Migration with the Full Acoustic Wave Equation) examined an alternative approach based on the full acoustic wave equation. The 2D, Fourier type algorithm which was developed was tested by Kosloff and Baysal against synthetic data and against physical model data. The results indicated that such a scheme gives accurate migration for complicated structures. This paper describes the development and testing of a vectorized, 3D migration program for the CYBER 205 using the Kosloff/Baysal method. The program can accept as many as 65,536 zero offset (stacked) traces

Elemental, isotopic, and geochronological variability in Mogollon-Datil volcanic province archaeological obsidian, southwestern USA: Solving issues of intersource discrimination

Solving issues of intersource discrimination in archaeological obsidian is a recurring problem in geoarchaeological investigation, particularly since the number of known sources of archaeological obsidian worldwide has grown nearly exponentially in the last few decades, and the complexity of archaeological questions asked has grown equally so. These two parallel aspects of archaeological investigation have required more exacting understanding of the geological relationship between sources and the more accurate analysis of these sources of archaeological obsidian. This is particularly the case in the North American Southwest where the frequency of archaeological investigation is some of the highest in the world, and the theory and method used to interpret that record has become increasingly nuanced. Here, we attempt to unravel the elemental similarity of archaeological obsidian in the Mogollon-Datil volcanic province of southwestern New Mexico where some of the most important and extensively distributed sources are located and the elemental similarity between the sources is great even though the distance between the sources is large. Uniting elemental, isotopic, and geochronological analyses as an intensive pilot study, we unpack this complexity to provide greater understanding of these important sources of archaeological obsidian

Analysis of Aneuploidy During Mouse Spermatogenesis

Successful transition through meiosis is required for production of chromosomally-balanced gametes. When chromosome segregation goes awry during meiosis, aneuploidy can occur. Unfortunately, the mechanisms behind this nondisjunction are not well understood. Therefore, this dissertation has focused on learning more about the causative factors associated with aneuploidy during spermatogenesis. Are there factors that are always associated with leading to production of aneuploid sperm? One of the main goals of this dissertation is to find mouse models to study what factors may be involved in chromosome malsegregation; such as pairing, recombination, and transition through the division phases of meiosis. The first part of the dissertation will be an introduction into what is known about gamete aneuploidy. This section will review what is known about how meiotic error may arise in both humans and the mouse. The introduction will discuss links between factors that are thought to be associated with aneuploidy, and this dissertation will extend this information into new directions in analysis of predisposing factors of gamete aneuploidy. Part II focuses on a novel mouse model for gamete aneuploidy. PL/J males were found to be an important mouse model for both gamete aneuploidy and abnormal sperm-head morphology. In addition, it was found that PL/J males exhibit both genetic and phenotypic complexity in regard to the traits of aneuploidy and abnormal sperm-head morphology. Parts III-VII discuss other useful mouse models for study of gamete aneuploidy. Robertsonian heterozygous (Rb/+) translocation mice and Mlh1 -/- mice were both used to examine what happens when meiosis goes awry. For example, both Rb/+ and Mlh1 -/- mice were found to have a checkpoint that most likely detects unaligned or abnormal chromosome configurations. High percentages of MI spermatocytes in these mice were found to be apoptotic. In Part V, Brca2 -/- mice were rescued with the human BRCA2 transgene. These mice survive, but are sterile. Analysis was performed to determine the point of arrest in these mice and if they have features of a normal progression through meiosis. The last two chapters focus on different approaches for the study of aneuploidy. Part VI examines whether the topoisomerase-II inhibitor, etoposide, can induce meiotic nondisjunction. It was shown by sperm FISH that etoposide does induce meiotic nondisjunction, with the highest frequency of nondisjunction occurring at MII. The next part of this section discusses use of a novel screen for detection of new meiotic mutations. A sperm FISH screen was used in this study to detect dominant mutations. This study showed that although screening by sperm FISH is feasible, it is not a practical screen when large numbers of gametes need to be scored. The last section, Part VIII, is a summary of what we have learned and what directions should be taken to increase our understanding of how meiotic error arises leading to nondisjunction. This section will compare and contrast what we have learned from each mouse model and what factors may contribute to production of aneuploid sperm. The discovery of factors associated with aneuploidy will be essential in learning how to prevent the deleterious effects that occur as a result of malsegregation of chromosomes

Letter from Fred D. Pyle

Letter concerning a copy of the catalogue for Utah Agricultural College

REST/NRSF Knockdown Alters Survival, Lineage Differentiation and Signaling in Human Embryonic Stem Cells.

REST (RE1 silencing transcription factor), also known as NRSF (neuron-restrictive silencer factor), is a well-known transcriptional repressor of neural genes in non-neural tissues and stem cells. Dysregulation of REST activity is thought to play a role in diverse diseases including epilepsy, cancer, Down's syndrome and Huntington's disease. The role of REST/NRSF in control of human embryonic stem cell (hESC) fate has never been examined. To evaluate the role of REST in hESCs we developed an inducible REST knockdown system and examined both growth and differentiation over short and long term culture. Interestingly, we have found that altering REST levels in multiple hESC lines does not result in loss of self-renewal but instead leads to increased survival. During differentiation, REST knockdown resulted in increased MAPK/ERK and WNT signaling and increased expression of mesendoderm differentiation markers. Therefore we have uncovered a new role for REST in regulation of growth and early differentiation decisions in human embryonic stem cells

Clouds, photolysis and regional tropospheric ozone budgets.

We use a three-dimensional chemical transport model to examine the shortwave radiative effects of clouds on the tropospheric ozone budget. In addition to looking at changes in global concentrations as previous studies have done, we examine changes in ozone chemical production and loss caused by clouds and how these vary in different parts of the troposphere. On a global scale, we find that clouds have a modest effect on ozone chemistry, but on a regional scale their role is much more significant, with the size of the response dependent on the region. The largest averaged changes in chemical budgets (±10–14%) are found in the marine troposphere, where cloud optical depths are high. We demonstrate that cloud effects are small on average in the middle troposphere because this is a transition region between reduction and enhancement in photolysis rates. We show that increases in boundary layer ozone due to clouds are driven by large-scale changes in downward ozone transport from higher in the troposphere rather than by decreases in in-situ ozone chemical loss rates. Increases in upper tropospheric ozone are caused by higher production rates due to backscattering of radiation and consequent increases in photolysis rates, mainly J(NO2). The global radiative effect of clouds on isoprene, through decreases of OH in the lower troposphere, is stronger than on ozone. Tropospheric isoprene lifetime increases by 7% when taking clouds into account. We compare the importance of clouds in contributing to uncertainties in the global ozone budget with the role of other radiatively-important factors. The budget is most sensitive to the overhead ozone column, while surface albedo and clouds have smaller effects. However, uncertainty in representing the spatial distribution of clouds may lead to a large sensitivity of the ozone budget components on regional scales

Re International Association of Machinists, Lodge 717, and Orenda Ltd

Employee Grievance alleging failure by the company to provide weekly indemnity for non-occupational sickness. The facts: On June 19, 1968, Mr. Garden, the grievor, went to Orenda\u27s plant doctor for an examination. He was referred to his family doctor. That same day, and again on June 24th, he consulted Dr. W.K. Taylor who had been his doctor for some years. On June 25th, Dr. Taylor signed an Attending Physician\u27s Statement for submission to the company in support of a claim by the grievor for weekly indemnity for non-occupational sickness. The statement noted under the heading diagnosis the following: neurodermatitis both hands, duodenal ulcer symptoms . It is also noted on the statement that the patient has been totally disabled (unable to work) from June 19, 1968, and that he should be able to return to work on July 2, 1968. Under the heading how long will the patient be partially disabled? the answer given is for the same period