The influence of process gas type on the enamel surface condition of a high power diode laser generated single-stage ceramic tile grout seal

Almost all laser materials processing operations require the simultaneous use of an process or assist gas. This paper examines the use of O2, Ar, N2 and He as process gasses during the firing of a vitreous enamel to form a single-stage ceramic tile grout seal with a high power diode laser (HPDL) and the effects thereof on the surface condition of the glaze. The findings revealed marked differences in the surface condition of the HPDL generated enamel glaze depending upon the process gas used. The use of O2 as the process gas was seen to result in glazes with far fewer microcracks and porosities than those generated with any of the other three gasses, particularly He. Such differences were found to be due to the ability of the smaller O2 gas molecules to dissolve molecularly into the open structure of the HPDL generated enamel glaze and also, the inherent reactiveness of O2 which consequently effects exothermic reactions when it is used as a process gas. Both occurrences were seen, in turn, to affect the cooling rate and therefore the tendency of the molten glaze to generate microcracks when cooled

A comparative investigation of the wear characteristics of a high power diode laser generated single-stage tile grout and commercial epoxy tile grout

A comparative study of a single-stage ceramic tile grout, generated using a 60 W high power diode laser (HPDL), and a commercially available tile grout has determined the wear characteristics of the two materials. Within both normal and corrosive environmental conditions, the single-stage ceramic tile grout proved to have a superior wear rate over the epoxy tile grout, 0.9 mg/cm2/h compared with 125 mg/cm2/h when in an HNO3 environment respectively. Likewise, life assessment testing revealed that the single-stage ceramic tile grout gave an increase in wear life of 4 to 42 times over the commercially available epoxy tile grout, depending upon the corrosive environment. It is believed that the economic and material benefits to be gained from the deployment of such an effective and efficient means of sealing ceramic tiles could be significant

Directing the Development of a University Centre of Criminology

The original sod out of which the University of Toronto\u27s Centre of Criminology grew was a proposal that I drew up while teaching a course in criminology as part of the LL.B. curriculum in the Faculty of Law at Dalhousie University in 1958-59.1 The proposal reviewed the extent of criminological teaching and research in Canada, and drew particular attention to the lack of implementation of the recommendations of the Fauteux Committee - a committee established in 1956 by the Canadian federal government to study the country\u27s penal system and to make recommendations for change and improvement. 2 In its report, the Fauteux Committee had reiterated the exhortations of the Archambault Royal Commission, in 1938, 3 that the universities in Canada should become actively involved in the education and training of persons suitable to serve in the penal system

Synaptophysin-Ki67 double stain: a novel technique that improves interobserver agreement in the grading of well-differentiated gastrointestinal neuroendocrine tumors.

A common problem in the assessment of Ki67 proliferative index in well-differentiated gastrointestinal neuroendocrine tumors is distinguishing tumor from non-tumor. This is because background stromal lymphocytes, entrapped non-neoplastic glands, and the delicate vascular network characteristic of neuroendocrine tumors frequently contain a subset of proliferating cells. Furthermore, in small biopsies, crush and cautery artifact can alter the morphologic appearance of tumor cells, making the Ki67 proliferative index more difficult to assess. To address these issues, we developed a synaptophysin-Ki67 double stain using a commercially available immunohistochemistry kit, allowing simultaneous visualization of tumor and proliferating nuclei. To test this method, three gastrointestinal pathologists individually graded 50 gastrointestinal neuroendocrine tumors first using synaptophysin-Ki67 double-stained slides and then, after a washout period, using Ki67-only stained slides (along with routine hematoxylin- and eosin-stained slides). Interobserver agreement on Ki67 proliferative index was moderate using the Ki67-only stained slides (intraclass correlation 0.51, 95% confidence interval: 0.35-0.66) and improved using the synaptophysin-Ki67 double stain (intraclass correlation 0.79, 95% confidence interval: 0.69-0.86). Similarly, interobserver agreement on tumor grade was fair with Ki67-only stained slides (κ=0.39, P<0.001) and improved with the double stain (κ=0.58, P<0.001). Analysis of individual pathologists' scores revealed that fewer total number of tumor cells counted correlated with higher grade designation and appeared to contribute to grade discordance. In tumors cited as particularly challenging to assess by the pathologists, three of four tumors were grade discordant with the Ki67-only stain, whereas all four tumors were grade concordant with the synaptophysin-Ki67 stain. The synaptophysin-Ki67 double stain is the first technique to address specifically the histomorphologic challenges of evaluating Ki67 proliferative index in well-differentiated gastrointestinal neuroendocrine tumors. Although further validation is needed, this study provides evidence that the synaptophysin-Ki67 double stain can improve interobserver agreement

On the Universality of Mesoscience: Science of 'the in-between'

The universality of mesoscales, ranging between elemental particles and the universe, is discussed here by reviewing widely disparate fields and presenting four cases, at differing hierarchical levels, from chemistry, chemical engineering, meteorology, through to astronomy. An underpinning concept, "Compromise in competition", is highlighted between various dominant, but competing mechanisms, and is identified here to be the universal origin of complexity and diversity in such examples. We therefore advance this as a key underlying principle of an emerging science -- Mesoscience.Comment: 8 pages, 1 figur

Measuring the Decorrelation Times of Fourier Modes in Simulations

We describe a method to study the rate at which modes decorrelate in numerical simulations. We study the XY model updated with the Metropolis and Wolff dynamics respectively and compute the rate at which each eigenvector of the dynamics decorrelates. Our method allows us to identify the decorrelation time for each mode separately. We find that the autocorrelation function of the various modes is markedly different for the `local' Metropolis compared to the `non-local' Wolff dynamics. Equipped with this new insight, it may be possible to devise highly efficient algorithms.Comment: 16 pp (LaTeX), PUPT-1378 , IASSNS-HEP-93/

Determining Interfaces Using Type Inference

Porting software usually requires understanding what library functions the program being ported uses since this functionality must be either found or reproduced in the ported program's new environment. This is usually done manually through code inspections. We propose a type inference algorithm able to infer basic information about the library functions a particular C program uses in the absence of declaration information for the library (e.g., without header files). Based on a simple but efficient inference algorithm, we were able to infer declarations for much of the PalmOS API from the source of a twenty-seven-thousand-line C program. Such a tool will aid in the problem of program understanding when porting programs, especially from poorly-documented or lost legacy environments

Stability Analysis of Roughness Array Wake in a High-Speed Boundary Layer

Computations are performed to examine the effects of both an isolated and spanwise periodic array of trip elements on a high-speed laminar boundary layer, so as to identify the potential physical mechanisms underlying an earlier transition to turbulence as a result of the trip(s). In the context of a 0.333 scale model of the Hyper-X forebody configuration, the time accurate solution for an array of ramp shaped trips asymptotes to a stationary field at large times, indicating the likely absence of a strong absolute instability in the mildly separated flow due to the trips. A prominent feature of the wake flow behind the trip array corresponds to streamwise streaks that are further amplified in passing through the compression corner. Stability analysis of the streaks using a spatial, 2D eigenvalue approach reveals the potential for a strong convective instability that might explain the earlier onset of turbulence within the array wake. The dominant modes of streak instability are primarily sustained by the spanwise gradients associated with the streaks and lead to integrated logarithmic amplification factors (N factors) approaching 7 over the first ramp of the scaled Hyper-X forebody, and substantially higher over the second ramp. Additional computations are presented to shed further light on the effects of both trip geometry and the presence of a compression corner on the evolution of the streaks