1,760 research outputs found

    A representation theorem for integral rigs and its applications to residuated lattices

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    We prove that every integral rig in Sets is (functorially) the rig of global sections of a sheaf of really local integral rigs. We also show that this representation result may be lifted to residuated integral rigs and then restricted to varieties of these. In particular, as a corollary, we obtain a representation theorem for pre-linear residuated join-semilattices in terms of totally ordered fibers. The restriction of this result to the level of MV-algebras coincides with the Dubuc-Poveda representation theorem.Comment: Manuscript submitted for publicatio

    Nonadiabatic Study of Dynamic Electronic Effects during Brittle Fracture of Silicon

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    It has long been observed that brittle fracture of materials can lead to emission of high energy electrons and UV photons, but an atomistic description of the origin of such processes has lacked. We report here on simulations using a first-principles-based electron force field methodology with effective core potentials to describe the nonadiabatic quantum dynamics during brittle fracture in silicon crystal. Our simulations replicate the correct response of the crack tip velocity to the threshold critical energy release rate, a feat that is inaccessible to quantum mechanics methods or conventional force-field-based molecular dynamics. We also describe the crack induced voltages, current bursts, and charge carrier production observed experimentally during fracture but not previously captured in simulations. We find that strain-induced surface rearrangements and local heating cause ionization of electrons at the fracture surfaces

    Sustainability Assessment of indicators for integrated water resources management

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    The scientific community strongly recommends the adoption of indicators for the evaluation and monitoring of progress towards sustainable development. Furthermore, international organizations consider that indicators are powerful decision-making tools. Nevertheless, the quality and reliability of the indicators depends on the application of adequate and appropriate criteria to assess them. The general objective of this study was to evaluate how indicators related to water use and management perform against a set of sustainability criteria. Our research identified 170 indicators related to water use and management. These indicators were assessed by an international panel of experts that evaluated whether they fulfil the four sustainability criteria: social, economic, environmental, and institutional. We employed an evaluation matrix that classified all indicators according to the DPSIR (Driving Forces, Pressures, States, Impacts and Responses) framework. A pilot study served to test and approve the research methodology before carrying out the full implementation. The findings of the study show that 24 indicators comply with the majority of the sustainability criteria; 59 indicators are bi-dimensional (meaning that they comply with two sustainability criteria); 86 are one-dimensional indicators (fulfilling just one of the four sustainability criteria) and one indicator do not fulfil any of the sustainability criteria.Postprint (author's final draft

    Efecto del enriquecimiento con nutrientes en la degradación de clorpirifos, malatión y metil paratión

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    Con el fin de evaluar el efecto del enriquecimiento con nutrientes (una sal de fósforo o un fertilizante comercial con N, P y K) como alternativa para mejorar la capacidad de degradación de los microorganismos en una matriz sólida, contaminada con los pesticidas organofosforados: clorpirifos, malatión y metil paratión, se realizaron experimentos de cultivo bajo condiciones controladas de oscuridad, temperatura y humedad por 30 días. En todos los tratamientos hubo degradación de los pesticidas; sin embargo, en el tratamiento con fósforo los tiempos para degradar el clorpirifos y el metil paratión fueron mayores. La presencia de los pesticidas no generó efectos tóxicos detectables sobre la microflora en ninguno de los tratamientos evaluados. La actividad biológica de las matrices no presentó una relación directa con la capacidad de degradación. Abstract In order to evaluate the effect of inorganic nutrient addition (phosphorus or commercial fertilizer) over the microbial degradation capacity present in a solid matrix contaminated with chlorpyrifos, malathion and methyl parathion, microcosms assays were held under controlled conditions of light, moisture and temperature for 30 days. Results showed that even though three treatments microorganisms were able to degrade the three organophosphorus pesticides, microorganisms of phosphorus-enrichment treatment were less efficient to degrade Chlorpyrifos and Methyl Parathion than microorganisms of Fertilizer-enrichment treatment. It was not observed a direct relation between mineralization and microbial pesticides degradation capacity. The microbial activity was not affected by the presence of organophosphorus pesticides

    Liquid culture for isolating microorganisms with potential to degrade methyl parathion from agricultural soils and organic waste.

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    The search for microorganisms with high capacity for pesticide degradation is a very interesting attempt to approach bioremediation strategies in order to prevent contamination. This study evaluates the potential of agricultural soils and solid organic waste cultures microbial isolation as a strategy for screening microorganisms with potential for Methyl parathion (MP) degradation. For the study, microbial consortia were recovered from the liquid fraction of suspension cultures of agricultural soils and solid organic waste. Then, the MP degradation ability and its toxic effect on microbial activity were determined during microbial incubations under laboratory controlled conditions. The results showed that it is not possible to recover the active microorganisms that have potential to degrade the MP from the agricultural soils. However, an active consortium that would degrade both MP and its degradation products was isolated from the organic solid waste

    An AB effect without closing a loop

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    We discuss the consequences of the Aharonov-Bohm effect in setups involving several charged particles, wherein none of the charged particles encloses a closed loop around the magnetic flux. We show that in such setups, the AB phase is encoded either in the relative phase of a bi-partite or multi-partite entangled photons states, or alternatively, gives rise to an overall AB phase that can be measured relative to another reference system. These setups involve processes of annihilation or creation of electron/hole pairs. We discuss the relevance of such effects in "vacuum Birefringence" in QED, and comment on their connection to other known effects.Comment: 4 pages, 3 figure

    Insecta, Coleoptera, Cerambycidae, Cerambycinae, Trachyderini: New state and country records from South America

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    Based on the revision of the collections of the Museu Nacional, Universidade Federal do Rio de Janeiro andthe National Museum of Natural History, Smithsonian Institution, the current work provides new localities for 32 speciesand two subspecies of Trachyderini from South America. Thirteen new country records from Argentina, Brazil, Colombia,Ecuador, Peru, Surinam and Venezuela and 35 new state records from Brazil are registered

    Large-scale Molecular Simulations of Hypervelocity Impact of Materials

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    We describe the application of the ReaxFF reactive force field with short-range distance-dependent exponential inner wall corrections and the non-adiabatic electron Force Field (eFF) for studying the hypervelocity impact (HVI) effects on material properties. In particular, to understanding nonequilibrium energy/mass transfer, high strain/heat rate material decomposition, defects formation, plastic flow, phase transitions, and electronic excitation effects that arise from HVI impact of soft and hard materials on different material surfaces. Novel results are presented on the single shock Hugoniot and shock chemistry of Nylon6-6, on the hypervelocity shock sensitivity of energetic materials with planar interfacial defects and on HVI chemistry of silicon carbide surfaces with diamondoid nanoparticles. Both methods provide a means to elucidate the chemical, atomic and molecular processes that occur within the bulk and at the surfaces of materials subjected to HVI conditions and constitute a critical tool to enabling technologies required for the next generation of energy, spatial, transportation, medical, and military systems and devices, among many others. This has proven to be extremely challenging, if not impossible, for experimental observations, mainly because the material states that occur are hard to isolate and their time scales for changes are too rapid (<1 ps). First principles quantum mechanics (QM) simulation methods have also been bounded by the prohibitive scaling cost of propagating the total Schrödinger equation for more than 100 atoms at finite temperatures and pressures
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