Magnesia-Based Cements: A Journey of 150 Years, and Cements for the Future?

This review examines the detailed chemical insights that have been generated through 150 years of work worldwide on magnesium-based inorganic cements, with a focus on both scientific and patent literature. Magnesium carbonate, phosphate, silicate-hydrate, and oxysalt (both chloride and sulfate) cements are all assessed. Many such cements are ideally suited to specialist applications in precast construction, road repair, and other fields including nuclear waste immobilization. The majority of MgO-based cements are more costly to produce than Portland cement because of the relatively high cost of reactive sources of MgO and do not have a sufficiently high internal pH to passivate mild steel reinforcing bars. This precludes MgO-based cements from providing a large-scale replacement for Portland cement in the production of steel-reinforced concretes for civil engineering applications, despite the potential for CO2 emissions reductions offered by some such systems. Nonetheless, in uses that do not require steel reinforcement, and in locations where the MgO can be sourced at a competitive price, a detailed understanding of these systems enables their specification, design, and selection as advanced engineering materials with a strongly defined chemical basis

The NOMAD experiment at the CERN SPS

The NOMAD experiment is a short base-line search for $\nu_{\mu}\rightarrow \nu_{\tau}$ oscillations in the CERN neutrino beam. The $\nu_{\tau}$'s are searched for through their charged-current interactions followed by the observation of the resulting $\tau^{-}$ through its electronic, muonic or hadronic decays. These decays are recognized using kinematical criteria necessitating the use of a light target which enables the reconstruction of individual particles produced in the neutrino interactions. This paper describes the various components of the NOMAD detector: the target and muon drift chambers, the electromagnetic and hadronic calorimeters, the preshower and transition radiation detectors, and the veto and trigger scintillation counters. The beam and data acquisition system are also described. The quality of the reconstruction of individual particles is demonstrated through the ability of NOMAD to observe K$^0_{\rm s}$'s, $\Lambda^0$'s and $\pi^0$'s. Finally, the observation of $\tau^{-}$ through its electronic decay being one of the most promising channels in the search, the identification of electrons in NOMAD is discussed

Hierarchical Pattern Mapping

We present a multi-scale algorithm for mapping a texture defined by an input image onto an arbitrary surface. It avoids the generation and storage of a new, specific texture. The idea is to progressively cover the surface by texture patches of various sizes and shapes, selected from a single input image. The process starts with large patches. A mapping that minimizes the texture fitting error with already textured neighbouring patches is selected. When this error is above a threshold, the patch is split into smaller ones, and the algorithm recursively looks for good fits at a smaller scale. The process ends when the surface is entirely covered. Our results show that the method correctly handles a wide set of texture patterns, which can be used at different mapping scales. Hierarchical texture mapping only outputs texture coordinates in the original texture for each triangle of the initial mesh. Rendering is therefore easy and memory cost minimal. Moreover the initial geometry is preserved

Low levels of second-line drug resistance among multidrug-resistant Mycobacterium tuberculosis isolates from Rwanda

Background: Multidrug-resistant tuberculosis (MDR-TB) has become a therapeutic problem in many parts of the world, necessitating the inclusion of second-line anti-tuberculosis drugs in specific treatment regimens. Methods: We studied the susceptibility of 69 MDR Mycobacterium tuberculosis isolates from Rwanda to second-line drugs by the BACTEC 460 method. Results: The results showed that 62 (89.9%) were resistant to rifabutin while a low rate (4.3%) of resistance was registered for ofloxacin; there was one case (1.4%) of resistance each for para-aminosalicylic acid, kanamycin, ethionamide, and clarithromycin. Conclusions: This information is important for devising an appropriate treatment regimen for MDR-TB patients in order to stop the spread of MDR strains and contain the acquisition of additional drug resistance in Rwanda. © 2007 International Society for Infectious Diseases.SCOPUS: ar.jinfo:eu-repo/semantics/publishe