119 research outputs found

    Comments on the Quantum Potential Approach to a Class of Quantum Cosmological Models

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    In this comment we bring attention to the fact that when we apply the ontological interpretation of quantum mechanics, we must be sure to use it in the coordinate representation. This is particularly important when canonical tranformations that mix momenta and coordinates are present. This implies that some of the results obtained by A. B\l aut and J. Kowalski-Glikman are incorrect.Comment: 7 pages, LaTe

    LA CONCIENCIA DE LA ACCIÓN

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    Tal vez yo no sea el mejor elemento de la Universidad en Educación Física y esto tal vez es debido a mis padres, a mis tíos, al barrio donde viví, a que mi casa no era grande o tal vez lo era mucho; tal vez se debe a que un día me castigaron o tal vez nunca lo hicieron. Sin embargo y por todas las razones anteriores y muchas más que hay, yo podría disculpar el porqué me tropiezo con cada cosa que tengo al frente o el porqué me cuesta trabajo hablar y caminar al mismo tiempo. Las disculpas como su nombre lo indica “Lo disculpan todo”

    Use of soda lime glass waste as silica supplier in fly ash based geopolymers

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    Geopolymers have been primarily proposed for the construction industry as a substitute for Portland cement considering the lower CO2 emissions associated with their production. The relatively high compressive strength and chemical inertness of geopolymers, in addition to the possibility to incorporate in the network hazardous waste materials, increase the current interest in this technology. Geopolymers are usually composed of an aluminosilicate source activated with a solution of sodium silicate and sodium hydroxide. The present study evaluates the feasibility of using waste glass as silica source instead of water glass in geopolymer production, using sodium hydroxide as the only non-waste material.The samples were developed changing the SiO2/Al2O3 molar ratio and the molarity of the sodium hydroxide solution. Fig. 1 shows that the compressive strength tends to rise as the molarity of the solution as well as the SiO2/Al2O3 molar ratio increase. The compressive strength values, around 45 MPa, are comparable to those of traditional Portland cement and they are remarkable considering the high amount of waste glass (70% wt.) incorporated in the matrix . SEM pictures demonstrated the formation of a compact matrix indicating the high reaction degree of the raw materials. Please click Additional Files below to see the full abstract

    Glass-Ceramic Foams from 'Weak Alkali Activation' and Gel-Casting ofWaste Glass/Fly Ash Mixtures

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    A 'weak alkali activation' was applied to aqueous suspensions based on soda lime glass and coal fly ash. Unlike in actual geopolymers, an extensive formation of zeolite-like gels was not expected, due to the low molarity of the alkali activator (NaOH) used. In any case, the suspension underwent gelation and presented a marked pseudoplastic behavior. A significant foaming could be achieved by air incorporation, in turn resulting from intensive mechanical stirring (with the help of a surfactant), before complete hardening. Dried foams were later subjected to heat treatment at 700-900 °C. The interactions between glass and fly ash, upon firing, determined the formation of new crystal phases, particularly nepheline (sodium alumino-silicate), with remarkable crushing strength (~6 MPa, with a porosity of about 70%). The fired materials, finally, demonstrated a successful stabilization of pollutants from fly ash and a low thermal conductivity that could be exploited for building applications

    Glass-ceramic foams from 'weak alkali activation' and gel-casting of waste glass/fly ash mixtures

    Get PDF
    A 'weak alkali activation' was applied to aqueous suspensions based on soda lime glass and coal fly ash. Unlike in actual geopolymers, an extensive formation of zeolite-like gels was not expected, due to the low molarity of the alkali activator (NaOH) used. In any case, the suspension underwent gelation and presented a marked pseudoplastic behavior. A significant foaming could be achieved by air incorporation, in turn resulting from intensive mechanical stirring (with the help of a surfactant), before complete hardening. Dried foams were later subjected to heat treatment at 700-900 \ub0C. The interactions between glass and fly ash, upon firing, determined the formation of new crystal phases, particularly nepheline (sodium alumino-silicate), with remarkable crushing strength (~6 MPa, with a porosity of about 70%). The fired materials, finally, demonstrated a successful stabilization of pollutants from fly ash and a low thermal conductivity that could be exploited for building applications

    Comments on "There is no axiomatic system for the quantum theory"

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    In a recent paper, Nagata [1] claims to derive inconsistencies from quantum mechanics. In this paper, we show that the inconsistencies do not come from quantum mechanics, but from extra assumptions about the reality of observables

    Can biological quantum networks solve NP-hard problems?

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    There is a widespread view that the human brain is so complex that it cannot be efficiently simulated by universal Turing machines. During the last decades the question has therefore been raised whether we need to consider quantum effects to explain the imagined cognitive power of a conscious mind. This paper presents a personal view of several fields of philosophy and computational neurobiology in an attempt to suggest a realistic picture of how the brain might work as a basis for perception, consciousness and cognition. The purpose is to be able to identify and evaluate instances where quantum effects might play a significant role in cognitive processes. Not surprisingly, the conclusion is that quantum-enhanced cognition and intelligence are very unlikely to be found in biological brains. Quantum effects may certainly influence the functionality of various components and signalling pathways at the molecular level in the brain network, like ion ports, synapses, sensors, and enzymes. This might evidently influence the functionality of some nodes and perhaps even the overall intelligence of the brain network, but hardly give it any dramatically enhanced functionality. So, the conclusion is that biological quantum networks can only approximately solve small instances of NP-hard problems. On the other hand, artificial intelligence and machine learning implemented in complex dynamical systems based on genuine quantum networks can certainly be expected to show enhanced performance and quantum advantage compared with classical networks. Nevertheless, even quantum networks can only be expected to efficiently solve NP-hard problems approximately. In the end it is a question of precision - Nature is approximate.Comment: 38 page
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