The sustainable implementation of computers in school districts : a case study in the Free State Province of South Africa

This study investigates influences on the sustainability of a computers-in-schools project during the implementation phase thereof. The CALIS Project (1992-1996) is the unit of analysis. A qualitative case study research design is used to elicit data, in the form of participant narratives, from people who were involved in the regional management of the Project, as well as teachers who implemented the Project in their classrooms. These narratives are then analysed from a post-modern perspective (Kvale, 1996). The analysis reveals personal, programmatic, physical and systemic influences on the Project. These influences can be identified on all structural levels of the education system (Mooij and Smeets, 2001). Furthermore, metaphoric patterning across narratives is analysed in terms of implicatures, postulated by Relevance Theory (Sperber and Wilson, 1995). Analysis of the data provides evidence in support of Fullan’s (2005) definition of sustainability as a quality of dynamic, complex systems. Personal, programmatic, physical and systemic influences on the Project are found to be interrelated on, and across, structural levels of the system. In addition, influences are dynamically related to the changing Project in particular host environments (Cavallo, 2004). The resulting ecological or viral growth is characteristic of complex systems, where further development is indeterminate.Thesis (PhD (Curriculum Studies))--University of Pretoria, 2006.Curriculum Studiesunrestricte

Cement nanotubes: on chemical gardens and cement

© 2016 Springer Science+Business Media New York“Do cement nanotubes exist?” is a question that has recently been asked. The answer is yes, they do exist. The evidence is in the literature, in tens of papers showing in detail chemical garden-type tubes in cement from the nanoscale upwards that were published in the 1970s and 1980s. Here, we present a nano-review of the literature

Integrated market selection and production planning: complexity and solution approaches

Emphasis on effective demand management is becoming increasingly recognized as an important factor in operations performance. Operations models that account for supply costs and constraints as well as a supplier's ability to in°uence demand characteristics can lead to an improved match between supply and demand. This paper presents a new class of optimization models that allow a supplier to select, from a set of potential markets, those markets that provide maximum profit when production/procurement economies of scale exist in the supply process. The resulting optimization problem we study possesses an interesting structure and we show that although the general problem is NP-complete, a number of relevant and practical special cases can be solved in polynomial time. We also provide a computationally very effcient and intuitively attractive heuristic solution procedure that performs extremely well on a large number of test instances

Expression of miR-206 in human islets and its role in glucokinase regulation

Inappropriate insulin secretion from β-cells is considered as an early sign of impaired glucose tolerance and type 2 diabetes (T2D). Glucokinase (GCK) is an important enzyme that regulates glucose metabolism and ensures that the normal circulating glucose concentrations are maintained. GCK expression is induced by glucose and regulated via transcription factors and regulatory proteins. Recently, microRNA-206 (miR-206) was reported to regulate GCK and alter glucose tolerance in normal and high-fat diet-fed mice. Although the study findings have implications for human diabetes, studies in human islets are lacking. Here, we analyze human islets from individuals without or with T2D, using TaqMan-based real-time qPCR at the tissue (isolated islet) level as well as at single cell resolution, to assess the relationship between miR-206 and GCK expression in normal and T2D human islets. Our data suggest that, unlike mouse islets, human islets do not exhibit any correlation between miR-206 and GCK transcripts. These data implicate the need for further studies aimed toward exploring its potential role(s) in human islets

Fluctuations in the Cosmic Microwave Background I: Form Factors and their Calculation in Synchronous Gauge

It is shown that the fluctuation in the temperature of the cosmic microwave background in any direction may be evaluated as an integral involving scalar and dipole form factors, which incorporate all relevant information about acoustic oscillations before the time of last scattering. A companion paper gives asymptotic expressions for the multipole coefficient $C_\ell$ in terms of these form factors. Explicit expressions are given here for the form factors in a simplified hydrodynamic model for the evolution of perturbations.Comment: 35 pages, no figures. Improved treatment of damping, including both Landau and Silk damping; inclusion of late-time effects; several references added; minor changes and corrections made. Accepted for publication in Phys. Rev. D1

Periodontal breakdown inter-tooth relationships in estimating periodontitis-related tooth loss

Item does not contain fulltextOBJECTIVES: The reasons for tooth extraction are rarely recorded in epidemiological datasets. It poses a diagnostic challenge to determine if tooth loss is related to periodontal disease (TLPD). The present study aimed to assess the inter-tooth relationships based on the periodontal characteristics of existing teeth. METHODS: A cross-sectional dataset of 8,978 participants with complete periodontal examination (including probing pocket depth [PPD] and clinical attachment loss [CAL]) in the NHANES 2009-2014 was used in this study. Spearman rank correlation was applied to assess the inter-tooth correlations of PPD/CAL among 28 teeth after adjustment for relevant confounders. We further verify our findings in the Java Project on Periodontal Disease with TLPD information available (the number of TLPD = 12). RESULTS: Strong PPD/CAL correlations were observed in adjacent teeth (r for PPD = 0.652, r for CAL = 0.597; false discovery rate [FDR] <0.05) rather than those on non-adjacent teeth (r for PPD = 0.515, r for CAL = 0.476; FDR <0.05). The correlations increased among severe periodontitis cases (CAL ≥5 mm or PPD ≥6 mm). In line with this, we further observed that the teeth adjacent to the TLPD tooth had the most alveolar bone loss in the Java dataset. CONCLUSION: The periodontitis parameters (PPD/CAL) of adjacent teeth could be a potential indicator to estimate TLPD when actual reasons for tooth extraction are unknown. CLINICAL SIGNIFICANCE: Periodontally compromised teeth adjacent to a lost tooth may help estimate whether the loss could be related to periodontal disease when the actual extraction reasons are unknown

Biomimetic Sniffing Improves the Detection Performance of a 3D Printed Nose of a Dog and a Commercial Trace Vapor Detector

Unlike current chemical trace detection technology, dogs actively sniff to acquire an odor sample. Flow visualization experiments with an anatomically-similar 3D printed dog’s nose revealed the external aerodynamics during canine sniffing, where ventral-laterally expired air jets entrain odorant-laden air toward the nose, thereby extending the “aerodynamic reach” for inspiration of otherwise inaccessible odors. Chemical sampling and detection experiments quantified two modes of operation with the artificial nose-active sniffing and continuous inspiration-and demonstrated an increase in odorant detection by a factor of up to 18 for active sniffing. A 16-fold improvement in detection was demonstrated with a commercially-available explosives detector by applying this bio-inspired design principle and making the device “sniff” like a dog. These lessons learned from the dog may benefit the next-generation of vapor samplers for explosives, narcotics, pathogens, or even cancer, and could inform future bio-inspired designs for optimized sampling of odor plumes.United States. Department of Homeland Security. Advanced Research Projects Agency (Interagency Agreement HSHQPM-13-X-00107)United States. Air Force (Contract FA8721-05-C-0002)United States. Air Force (Contract FA8702-15-D-0001

Reliability and bifurcation in neurons driven by multiple sinusoids

The brain produces dynamical rhythms at many frequencies that shift in amplitude and phase. To understand the functional consequences of mixtures of oscillations at the single cell level, we recorded the spike trains from single rat cortical neurons in vitro in response to two mixed sine wave currents. The reliability of spike timing was measured as a function of the relative power, phase and frequencies of the sine wave mixture. Peaks in the reliability were observed at a preferred phase difference, frequency and relative power. These results have a natural interpretation in terms of spike train attractors and bifurcations