On polynomial reconstruction of disconnected graphs

Let H be a disconnected graph with connected components H1, H2, ..., Ht. If the characteristic polynomial of H were not reconstructible from the deck of characteristic polynomials of its one-vertex deleted subgraphs, then H would consist of exactly two connected components of the same order. We show that if H has a pendant edge in the component with the larger number of edges or if the smaller component of H is a tree, then H is polynomial reconstructible.peer-reviewe

About optimal location of sensors and actuators for the control of flexible structures

This work deals with the problem of efficient location of sensors and actuators encountered in the domain of active control of flexible structure. It appears that the optimal solution depends upon the type ofcontrol scheme that is used as well as the kinds of sensors and actuators that are implemented, and on the criterion that is considered. This paper recalls and discusses some approaches that are presented in the literature and presents some results that are obtained with a mock-up equipped with piezoelectric sensors and actuators

Alkali activated binders based on municipal solid waste Incineration bottom ash

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Education and older adults at the University of the Third Age

This article reports a critical analysis of older adult education in Malta. In educational gerontology, a critical perspective demands the exposure of how relations of power and inequality, in their myriad forms, combinations, and complexities, are manifest in late-life learning initiatives. Fieldwork conducted at the University of the Third Age (UTA) in Malta uncovered the political nature of elder-learning, especially with respect to three intersecting lines of inequality - namely, positive aging, elitism, and gender. A cautionary note is, therefore, warranted at the dominant positive interpretations of UTAs since late-life learning, as any other education activity, is not politically neutral.peer-reviewe

A quantitative method for determining the antiwashout characteristics of cement-based dental materials including mineral trioxide aggregate

Aim: To introduce and assess a novel method for measuring washout resistance of cement-based dental materials, including mineral trioxide aggregate (MTA), to qualitatively verify the results with a clinical simulation and to evaluate the washout resistance of a new root-end filling material. Methodology: A method for assessment of washout resistance of root-end filling materials was developed by adapting the CRD-C 661-06 (a method for evaluating the resistance of freshly mixed concrete to wash-out in water), to permit testing of dental cements. White Portland cement (PC), MTA-Plus mixed with either water or a polymer-based antiwashout gel (MTA-AW), MTA-Angelus, IRM and amalgam were tested with either distilled water or HBSS as washout media. Additionally, the washout resistance was tested qualitatively by spraying the test materials at the terminus of simulated canals with a metered jet of water. Results: A mass loss of 2–7% for PC, 0.4–4% for MTA-Plus, 0.9% for MTA-AW, 5–10% for MTA-Angelus and 0% for IRM and amalgam was recorded with the modified CRD-C 661-06 method. No significant difference was found between using water and HBSS as washout media for the same material. The results of the modified CRD-C 661-06 method were similar to those obtained on the simulated canals. Conclusions: The modified CRD-C 661-06 method provided repeatable results that were comparable to the simulated clinical method. The antiwashout gel used with MTA-Plus reduced the material washout and was similar to IRM and amalgam.peer-reviewe

Geopolymers based on the valorization of Municipal Solid Waste Incineration residues

he proper management of Municipal Solid Waste (MSW) has become one of the main environmental commitments for developed countries due to the uncontrolled growth of waste caused by the consumption patterns of modern societies. Nowadays, municipal solid waste incineration (MSWI) is one of the most feasible solutions and it is estimated to increase in Europe where the accessibility of landfill is restricted. Bottom ash (BA) is the most significant by-product from MSWI as it accounts for 85-95 % of the solid product resulting from combustion, which is classified as a non-hazardous residue that can be revalorized as a secondary aggregate in road sub-base, bulk lightweight filler in construction. In this way, revalorization of weathered BA (WBA) for the production of geopolymers may be a good alternative to common reuse as secondary aggregate material; however, the chemical process to obtain these materials involves several challenges that could disturb the stability of the material, mainly from the environmental point of view. Accordingly, it is necessary that geopolymers are able to stabilize heavy metals contained in the WBA in order to be classified as non-hazardous materials. In this regard, the SiO2/Al2O3 ratio plays an important role for the encapsulation of heavy metals and other toxic elements. The aim of this research is to formulate geopolymers starting from the 0-2 mm particle size fraction of WBA, as a unique raw material used as aluminumsilicate precursor. Likewise, leaching tests of the geopolymers formulated were performed to assess their environmental impact. The findings show that it is possible to formulate geopolymers using 100 % WBA as precursor, although more investigations are needed to sustain that geopolymer obtained can be considered as non-hazardous materials