AESTHETIC CHARACTERISTICS OF GREEK ORNAMENTAL STONES ASSOCIATED WITH MINERAL, GEOCHEMICAL AND STRUCTURAL PROPERTIES

Τα εμπορικά μάρμαρα αποτελούν υλικά που δεν απαιτούν ιδιαίτερη επεξεργασία με υψηλή οικονομική αξία για την κατασκευαστική βιομηχανία. Τα πιο σημαντικάδιακοσμητικά πετρώματα στην Ελλάδα περιλαμβάνουν ασβεστόλιθους και μάρμαρα με ιδιαίτερα ποιοτικά χαρακτηριστικά και θεωρούνται προϊόντα ιδιαίτερης εμπορικής αξίας. Σε αυτή την εργασία μελετήθηκαν εβδομήντα τρία ανθρακικά δείγματα (ασβεστόλιθοι, δολομίτες και μάρμαρα) από όλη την Ελλάδα με σκοπό να καθοριστούν τα μακροσκοπικά και πετρογραφικά χαρακτηριστικά τους και να διερευνηθεί η ορυκτοχημική τους σύσταση και η γεωχημεία τους. Τα χρώματά τους ποικίλουν από λευκό έως τεφρό, εξαιτίας του περιεχομένου τους σε ασβεστίτη και δολομίτη, μαύρο σε βιτουμενιούχους ασβεστόλιθους, κίτρινο εξαιτίας της παρουσίας οξειδίων σιδήρου και αργιλικών ορυκτών, κόκκινο εξαιτίας των οξειδίων σιδήρου και μεικτών φάσεων ασβεστίτη και σιδηρίτη, καστανοπράσινο εξαιτίας της εμφάνισης οξειδίων σιδήρου μαζί με χλωρίτη και μοσχοβίτη, προσδίδοντας σχιστότητα στο πέτρωμα. Διάσπαρτες ασβεστιτικές και δολομιτικές φλέβες, όπως επίσης και εμφάνιση άλλων ορυκτών φάσεων όπως βαρύτης, επίδοτο και μαγνητίτης συμβάλλουν στη δημιουργία ιδιαίτερωνχαρακτηριστικών που προσδίδουν μοναδική εμφάνιση. Τα χαρακτηριστικά γνωρίσματα κάθε πετρώματος εξαρτώνται σημαντικά από το είδος των ορυκτών, τη σύσταση, κοκκομετρία και κατανομή τους, τη γεωχημεία και δομή τους.Commercial marble are almost ready-to-use materials with a high economic value for the building-construction industry. The most important ornamental stones in Greece include limestone and marble with notable qualitative features and are considered products of high commercial value. In this research, seventy-three carbonate samples (limestones, dolomites and marbles) from all over Greece have been studied to determine their macroscopic and petrographic features and to investigate their mineral chemistry and geochemistry. Their colors vary from whitish to gray due to their content of calcite and dolomite, black due to bitumens, yellow due to the presence of iron oxides and clay, red due to iron oxides and mixed phases of calcite- siderite, green-brownish due to the presence of iron oxides or muscovite and chlorite, giving schistosity to the rock. Scattered calcite and dolomite veins, as well as the occurrence of other minerals such as barite, epidote and magnetite, contribute to specific features, thus making their appearance unique. The particular characteristics of each stone depend highly upon the type of minerals present, their composition, grain size and extent of aggregation, their geochemistry and structure

Attitudes and perceptions towards summative e-assessment for free-text responses: A case study of a UAE university

© 2019, IGI Global. The key aim of this study is to provide an overview of students\u27 and instructors\u27 attitudes and perceptions towards the potential benefits and challenges of summative e-assessment for their writing courses at a UAE university. A mixed method of quantitative and qualitative analysis is used. The findings of the study revealed that a majority of student participants reported reasonable satisfaction with the e-assessment tool in terms of screen layout and background, interface design and ease of use and access. However, they indicated their preference to pen and paper exams. Instructor participants identified a number of challenges associated with using summative e-assessment in the writing courses, which would require educational institutions to make changes to promote the success of e-assessment

The 14C(n,g) cross section between 10 keV and 1 MeV

The neutron capture cross section of 14C is of relevance for several nucleosynthesis scenarios such as inhomogeneous Big Bang models, neutron induced CNO cycles, and neutrino driven wind models for the r process. The 14C(n,g) reaction is also important for the validation of the Coulomb dissociation method, where the (n,g) cross section can be indirectly obtained via the time-reversed process. So far, the example of 14C is the only case with neutrons where both, direct measurement and indirect Coulomb dissociation, have been applied. Unfortunately, the interpretation is obscured by discrepancies between several experiments and theory. Therefore, we report on new direct measurements of the 14C(n,g) reaction with neutron energies ranging from 20 to 800 keV

Asynchronous coupling of hybrid models for efficient simulation of multiscale systems

We present a new coupling approach for the time advancement of multi-physics models of multiscale systems. This extends the method of E et al. (2009) [5] to deal with an arbitrary number of models. Coupling is performed asynchronously, with each model being assigned its own timestep size. This enables accurate long timescale predictions to be made at the computational cost of the short timescale simulation. We propose a method for selecting appropriate timestep sizes based on the degree of scale separation that exists between models. A number of example applications are used for testing and benchmarking, including a comparison with experimental data of a thermally driven rarefied gas flow in a micro capillary. The multiscale simulation results are in very close agreement with the experimental data, but are produced almost 50,000 times faster than from a conventionally-coupled simulation

Generalizing Murray's law : an optimization principle for fluidic networks of arbitrary shape and scale

Murray's law states that the volumetric flow rate is proportional to the cube of the radius in a cylindrical channel optimized to require the minimum work to drive and maintain the fluid. However, application of this principle to the biomimetic design of micro/nano fabricated networks requires optimization of channels with arbitrary cross-sectional shape (not just circular) and smaller than is valid for Murray's original assumptions. We present a generalized law for symmetric branching that (a) is valid for any cross-sectional shape, providing that the shape is constant through the network; (b) is valid for slip flow and plug flow occurring at very small scales; and (c) is valid for networks with a constant depth, which is often a requirement for lab-on-a-chip fabrication procedures. By considering limits of the generalized law, we show that the optimum daughter-parent area ratio Γ, for symmetric branching into N daughter channels of any constant cross-sectional shape, is Γ=N−2/3Γ=N−2/3 for large-scale channels, and Γ=N−4/5Γ=N−4/5 for channels with a characteristic length scale much smaller than the slip length. Our analytical results are verified by comparison with a numerical optimization of a two-level network model based on flow rate data obtained from a variety of sources, including Navier-Stokes slip calculations, kinetic theory data, and stochastic particle simulations

Le rôle des organisations non gouvernementales dans la défense des droits de la personne en République populaire de Chine : le cas des organisations de défense des droits des femmes

Au cours du dernier siècle, les ONG se sont établies comme des acteurs incontournables des relations internationales telles que nous les connaissons aujourd'hui. Elles se sont implantées dans la majeure partie des pays du globe, y compris dans les régimes autoritaires comme la République populaire de Chine. Toutefois, le cadre dans lequel évoluent ces organisations en Chine demeure compliqué, notamment en raison des diverses mesures d'intimidation pratiquées par les autorités chinoises. Cette ingérence du pouvoir chinois dans les activités de la société civile laisse croire, en Occident, que les ONG chinoises n'exercent pas de véritable influence. Ce mémoire cherche donc à étudier de plus près ce postulat, afin de voir si les ONG jouent un rôle dans la promotion et la protection des droits de la personne en Chine, et, dans l'affirmative, de comprendre de quelle manière ce rôle est joué et d'examiner la portée de leur influence. Ce mémoire montre que le développement d'un régime international de promotion et de protection des droits de la personne a eu un impact sur l'adoption de normes relatives à ces questions en Chine, tout en exposant l'application irrégulière de ces normes au niveau interne. En outre, l'étude des pratiques des ONG, notamment concernant les droits des femmes, a permis d'établir que les ONG chinoises exercent une certaine influence quant à la promotion et à la protection des droits de la personne en Chine. Cette influence repose en partie sur les capacités et habiletés de certaines ONG à développer des stratégies pour tirer profit de leur situation de dépendance envers les autorités chinoises en utilisant leurs relations avec l'État comme levier d'influence. Toutefois, ce mémoire montre également que la portée des actions de ces organisations est limitée, plus particulièrement dans le cadre de certains enjeux sensibles pour le gouvernement chinois. En effet, l'ingérence du pouvoir chinois dans l'administration de la justice limite la portée des actions des ONG, et laisse supposer que l'avenir des ONG en Chine, tout comme celui des réformes juridiques, demeure incertain.\ud ______________________________________________________________________________ \ud MOTS-CLÉS DE L’AUTEUR : République populaire de Chine, Droits de la personne, Organisations non gouvernementales, Droits des femmes

beta-decay study of Cu-77

A beta-decay study of Cu-77 has been performed at the ISOLDE mass separator with the aim to deduce its beta-decay properties and to obtain spectroscopic information on Zn-77. Neutron-rich copper isotopes were produced by means of proton- or neutron-induced fission reactions on U-238. After the production, Cu-77 was selectively laser ionized, mass separated and sent to different detection systems where beta-gamma and beta-n coincidence data were collected. We report on the deduced half-live, decay scheme, and possible spin assignment of 77Cu