Measure dependence of 2D simplicial quantum gravity

We study pure 2D Euclidean quantum gravity with $R^2$ interaction on spherical lattices, employing Regge's formulation. We attempt to measure the string susceptibility exponent $\gamma_{\rm str}$ by using a finite-size scaling Ansatz in the expectation value of $R^2$. To check on effects of the path integral measure we investigate two scale invariant measures, the "computer" measure $dl/l$ and the Misner measure $dl/\sqrt A$.Comment: 3 pages, self unpacking uuencoded PostScript file, contribution to LATTICE9

Alternative perspectives on orality, literacy and education: a view from South Africa.

The question of the 'great divide' between orality and literacy has been critically addressed by various scholars of literacy, including social literacy theorists. This paper uses the notions of primary and secondary discourse across both oral and literate contexts to examine this 'divide'. Using evidence from the oral tradition of the Xhosa, it is shown that 'traditional' societies have well-established primary and secondary discourse types. Against this understanding, the issue of 'access' to Western academic literacy is examined. It is argued that within the changing context of South African society and as a direct result of former apartheid policies, individuals may have failed to acquire the cultural capital of both oral secondary and literate secondary discourse types. The literate secondary discourse practices of Xhosa-speaking students at univer¬sity are explored through an analysis of student writing. This paper then reports on several projects which attempt to address some of the concerns of academic staff with respect to student writing. In particular, this section argues for a broadening of the notion of 'academic literacy' and suggests some ways in which texts derived from the oral tradition may be used to develop awareness of secondary discourse types

Applying linguistics: Developing cognitive skills through multimedia

This paper examines the effectiveness of linguistic analysis in developing scientific thinking skills and scientific attitudes. It reports on a project established at a South Africa university in South Africa which engaged students in the analysis of code-mixed data. Students who participated in the project showed gains in being able to analyze linguistic data using problem solving skills. While transfer of such skills to mainstream science teaching was not investigated, the study confirms the effectiveness of linguistic analysis in engaging students in the activities associated with the development of skills for science

Far-field noise and internal modes from a ducted propeller at simulated aircraft takeoff conditions

The ducted propeller offers structural and acoustic benefits typical of conventional turbofan engines while retaining much of the aeroacoustic benefits of the unducted propeller. A model Advanced Ducted Propeller (ADP) was tested in the NASA Lewis Low-Speed Anechoic Wind Tunnel at a simulated takeoff velocity of Mach 0.2. The ADP model was designed and manufactured by the Pratt and Whitney Division of United Technologies. The 16-blade rotor ADP was tested with 22- and 40-vane stators to achieve cut-on and cut-off criterion with respect to propagation of the fundamental rotor-stator interaction tone. Additional test parameters included three inlet lengths, three nozzle sizes, two spinner configurations, and two rotor rub strip configurations. The model was tested over a range of rotor blade setting angles and propeller axis angles-of-attack. Acoustic data were taken with a sideline translating microphone probe and with a unique inlet microphone probe which identified inlet rotating acoustic modes. The beneficial acoustic effects of cut-off were clearly demonstrated. A 5 dB fundamental tone reduction was associated with the long inlet and 40-vane sector, which may relate to inlet duct geometry. The fundamental tone level was essentially unaffected by propeller axis angle-of-attack at rotor speeds of at least 96 percent design

Failure of the Regge approach in two dimensional quantum gravity

Regge's method for regularizing euclidean quantum gravity is applied to two dimensional gravity. We use two different strategies to simulate the Regge path integral at a fixed value of the total area: A standard Metropolis simulation combined with a histogramming method and a direct simulation using a Hybrid Monte Carlo algorithm. Using topologies with genus zero and two and a scale invariant integration measure, we show that the Regge method does not reproduce the value of the string susceptibility of the continuum model. We show that the string susceptibility depends strongly on the choice of the measure in the path integral. We argue that the failure of the Regge approach is due to spurious contributions of reparametrization degrees of freedom to the path integral.Comment: 27 pages, LaTex + uuencoded figure files (13 postscript files

Advances in UV-lithographic patterning of multi-layer waveguide stack for single mode polymeric RDL

This paper describes design and advances in process development for UV-lithography of planar single mode waveguides with openings for out-of-plane coupling µ-mirrors. Improvements to multi-layer direct patterning of OrmoCore/-Clad material system using UV-lithography are presented. Near square core cross sections are achieved. However, non uniformity across 4” wafer is shown due to varying proximity and UV-intensity. Openings in full stack with steep sidewalls without residual layer are patterned. Reduction in stack thickness for very small exposure doses due to inhibition even under inert atmosphere is shown. 45° -µ-mirrors are integrated in these openings to manufacture a U-link via a single mode waveguide and two adjacent micro-mirrors. Optical characterization of U-link demonstrates the feasibility of hybrid lithography approach. However, non-uniformity of core cross-section leads to cross coupling of planar waveguides. Outlook to further research on UV-lithography of multi-layer waveguide stack and alignment with µ-mirror printing is given

Laparoscopic lavage is superior to colon resection for perforated purulent diverticulitis:a meta-analysis

PURPOSE: Perforated diverticulitis often requires surgery with a colon resection such as Hartmann’s procedure, with inherent morbidity. Recent studies suggest that laparoscopic lavage may be an alternative surgical treatment. The aim of this study was to compare re-operations, morbidity, and mortality as well as health economic outcomes between laparoscopic lavage and colon resection for perforated purulent diverticulitis. METHODS: PubMed, Cochrane, Centre for Reviews and Dissemination, and Embase were searched. Published randomized controlled trials and prospective and retrospective cohorts with laparoscopic lavage and colon resection as interventions were identified. Trial limitations were assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) methodology. Re-operations, complications at 90 days classified according to Clavien-Dindo and mortality were extracted. RESULTS: Three randomized trials published between 2005 and 2015 were included in the analysis. The studies included a total of 358 patients with 185 patients undergoing laparoscopic lavage. At 12 months, the relative risk of having a re-operation was lower for laparoscopic lavage compared to colon resection in the two trials that had a 12 month follow-up. We found no significant differences in Clavien-Dindo complications classified more than level IIIB or mortality at 90 days. CONCLUSIONS: The risk for re-operations within the first 12 months after index surgery was lower for laparoscopic lavage compared to colon resection, with overall comparable morbidity and mortality. Furthermore, Hartmann’s resection was more costly than laparoscopic lavage. We therefore consider laparoscopic lavage a valid alternative to surgery with resection for perforated purulent diverticulitis