746 research outputs found

    Signal Transmission Across Tile Assemblies: 3D Static Tiles Simulate Active Self-Assembly by 2D Signal-Passing Tiles

    Full text link
    The 2-Handed Assembly Model (2HAM) is a tile-based self-assembly model in which, typically beginning from single tiles, arbitrarily large aggregations of static tiles combine in pairs to form structures. The Signal-passing Tile Assembly Model (STAM) is an extension of the 2HAM in which the tiles are dynamically changing components which are able to alter their binding domains as they bind together. For our first result, we demonstrate useful techniques and transformations for converting an arbitrarily complex STAM+^+ tile set into an STAM+^+ tile set where every tile has a constant, low amount of complexity, in terms of the number and types of ``signals'' they can send, with a trade off in scale factor. Using these simplifications, we prove that for each temperature τ>1\tau>1 there exists a 3D tile set in the 2HAM which is intrinsically universal for the class of all 2D STAM+^+ systems at temperature τ\tau (where the STAM+^+ does not make use of the STAM's power of glue deactivation and assembly breaking, as the tile components of the 2HAM are static and unable to change or break bonds). This means that there is a single tile set UU in the 3D 2HAM which can, for an arbitrarily complex STAM+^+ system SS, be configured with a single input configuration which causes UU to exactly simulate SS at a scale factor dependent upon SS. Furthermore, this simulation uses only two planes of the third dimension. This implies that there exists a 3D tile set at temperature 22 in the 2HAM which is intrinsically universal for the class of all 2D STAM+^+ systems at temperature 11. Moreover, we show that for each temperature τ>1\tau>1 there exists an STAM+^+ tile set which is intrinsically universal for the class of all 2D STAM+^+ systems at temperature τ\tau, including the case where τ=1\tau = 1.Comment: A condensed version of this paper will appear in a special issue of Natural Computing for papers from DNA 19. This full version contains proofs not seen in the published versio

    Basic parameters of three star clusters in the Small Magellanic Cloud: Kron 11, Kron 63 and NGC 121

    Get PDF
    We present observations for three star clusters, Kron 11, Kron 63 and NGC 121, in the Small Magellanic Cloud. We have studied their structure and derived their fundamental parameters by means of their luminosity functions, their colour magnitude diagrams and the Padova suite of isochrones. NGC 121 is a well-studied object, for which we confirm previous evidence about its old age and low-metal content, and have found that it is an undergoing mass segregation. Kron 11 and Kron 63 are poorly populated clusters which had never been studied so far. Kron 11 is several gigayears younger than NGC 121, while Kron 63 is basically a very young star aggregate. Both clusters are immersed in dense stellar fields which share the same population properties, suggesting that in their cases, cluster ages are consistent with typical ages of field stars.Instituto de Astrofísica de La PlataFacultad de Ciencias Astronómicas y Geofísica

    Basic parameters of three star clusters in the Small Magellanic Cloud: Kron 11, Kron 63 and NGC 121

    Get PDF
    We present observations for three star clusters, Kron 11, Kron 63 and NGC 121, in the Small Magellanic Cloud. We have studied their structure and derived their fundamental parameters by means of their luminosity functions, their colour magnitude diagrams and the Padova suite of isochrones. NGC 121 is a well-studied object, for which we confirm previous evidence about its old age and low-metal content, and have found that it is an undergoing mass segregation. Kron 11 and Kron 63 are poorly populated clusters which had never been studied so far. Kron 11 is several gigayears younger than NGC 121, while Kron 63 is basically a very young star aggregate. Both clusters are immersed in dense stellar fields which share the same population properties, suggesting that in their cases, cluster ages are consistent with typical ages of field stars.Instituto de Astrofísica de La PlataFacultad de Ciencias Astronómicas y Geofísica

    Basic parameters of three star clusters in the Small Magellanic Cloud: Kron 11, Kron 63 and NGC 121

    Get PDF
    We present observations for three star clusters, Kron 11, Kron 63 and NGC 121, in the Small Magellanic Cloud. We have studied their structure and derived their fundamental parameters by means of their luminosity functions, their colour magnitude diagrams and the Padova suite of isochrones. NGC 121 is a well-studied object, for which we confirm previous evidence about its old age and low-metal content, and have found that it is an undergoing mass segregation. Kron 11 and Kron 63 are poorly populated clusters which had never been studied so far. Kron 11 is several gigayears younger than NGC 121, while Kron 63 is basically a very young star aggregate. Both clusters are immersed in dense stellar fields which share the same population properties, suggesting that in their cases, cluster ages are consistent with typical ages of field stars.Instituto de Astrofísica de La PlataFacultad de Ciencias Astronómicas y Geofísica

    A depth-averaged model for non-isothermal thin-film rimming flow

    Get PDF
    A model for non-isothermal shear-driven thin-film flow on the inside surface of a stationary circular cylinder is presented. Motivated by an application to film flow in an aero-engine bearing chamber the model extends lubrication theory analysis of thin films to retain the important effects of inertia and heat convection.The accuracy of the depth-averaged temperature model is tested and comparisons illustrate the model is accurate for both conduction- and convection-dominant flows although local inaccuracies are introduced in regions exhibiting sharp changes in boundary temperature when convective effects are strong.Three rimming-flow configurations are considered: uni-directional flow with slowly-varying film height, a solution containing a steep front termed a shock, and a pooling solution where fluid accumulates in a recirculation at the base of the cylinder. The temperature field in the latter two which include recirculation features are greatly influenced by the strength of convection in the film

    APICULTURA SUSTENTÁVEL: PRODUÇÃO E COMERCIALIZAÇÃO DE MEL NO MEIO OESTE CATARINENSE

    Get PDF
    O presente trabalho tem como objetivo fomentar a produção de mel em larga escala, utilizando-se da apicultura de forma sustentável. A organização dos atores locais em Arranjos Produtivos será o principal mecanismo estratégico para gerar capital social e fomentar o projeto. A produção e a comercialização de mel no meio oeste catarinense será realizado através da criação de uma associação entre os moradores residentes no interior dos municípios integrantes da AMMOC (Associação dos Municípios do Meio Oeste Catarinense), e em pareceria com entidades necessárias na execução, como o Serviço Brasileiro de Apoio às Micro e Pequenas Empresas (SEBRAE), Associações de Apicultores e Meliponicultores de Santa Catarina (FAASC), Associação Brasileira dos Exportadores de Mel (ABEMEL), Empresa de Pesquisa Agropecuária e Extensão Rural de Santa Catarina (EPAGRI). A apicultura é uma atividade econômica de baixo impacto ambiental, que possibilita a utilização dos recursos naturais, de maneira que contribui com a manutenção e a preservação dos ecossistemas já existentes. O fato é que as abelhas atuam como polinizadores naturais tanto das espécies nativas como também das cultivadas, promovendo a preservação da biodiversidade e contribuindo com o equilíbrio do ecossistema.  Em sintese o projeto tem como meta a expansão no setor apiário na região da AMOC, e conclui-se ser uma atividade economicamente rentável e ecologicamente prudente, a fim de contribuir para o desenvolvimento, gerando emprego e renda para a regiã

    Toward an internally consistent astronomical distance scale

    Full text link
    Accurate astronomical distance determination is crucial for all fields in astrophysics, from Galactic to cosmological scales. Despite, or perhaps because of, significant efforts to determine accurate distances, using a wide range of methods, tracers, and techniques, an internally consistent astronomical distance framework has not yet been established. We review current efforts to homogenize the Local Group's distance framework, with particular emphasis on the potential of RR Lyrae stars as distance indicators, and attempt to extend this in an internally consistent manner to cosmological distances. Calibration based on Type Ia supernovae and distance determinations based on gravitational lensing represent particularly promising approaches. We provide a positive outlook to improvements to the status quo expected from future surveys, missions, and facilities. Astronomical distance determination has clearly reached maturity and near-consistency.Comment: Review article, 59 pages (4 figures); Space Science Reviews, in press (chapter 8 of a special collection resulting from the May 2016 ISSI-BJ workshop on Astronomical Distance Determination in the Space Age

    Percepção ambiental dos produtores e qualidade do solo em propriedades orgânicas e convencionais.

    Get PDF
    O sistema orgânico de produção deve resultar na utilização mais racional dos recursos naturais, sobretudo do solo. Os produtores orgânicos devem adotar práticas conservacionistas, além de atender a outros princípios deste sistema de produção. Neste trabalho foram avaliadas as práticas de manejo e conservação do solo adotadas por produtores orgânicos e convencionais nas regiões dos municípios de Socorro (Serra da Mantiqueira e Mogiana) e Ibiúna, situados no Estado de São Paulo. O objetivo dessa pesquisa foi verificar o grau de adoção de práticas conservacionistas pelos produtores e avaliar a qualidade do solo na agricultura orgânica e convencional. Foi elaborado e aplicado um questionário, com visitas locais para verificação das práticas conservacionistas e ocorrência de erosão, em 30 propriedades. Os resultados foram expressos em índices indicadores de diversidade de uso do solo, atitude conservacionista, percepção de erosão e do impacto sobre os recursos hídricos. Foram também realizadas análises de atributos químicos, físicos e biológicos indicadores da qualidade do solo. Concluiu-se que os produtores orgânicos têm maior percepção quanto à atitude conservacionista e nas propriedades orgânicas há maior diversidade de cultivos, embora não haja maior diversidade geral de uso do solo. A produção orgânica de alface, em Ibiúna proporcionou maior atividade biológica no solo e maior colonização por fungos micorrízicos arbusculares. O sistema orgânico possui maiores teores de matéria orgânica e menores de potássio e não houve diferença entre os atributos físicos do solo dos sistemas orgânico e convencional
    corecore