Clustering approaches and ensembles applied in the delineation of management classes in precision agriculture.

Abstract. This paper describes an experiment performed using different approaches for spatial data clustering, aiming to assist the delineation of management classes in Precision Agriculture (PA). These approaches were established from the partitional clustering algorithm Fuzzy c-Means (FCM), traditionally used in this context, and from the hierarchical clustering algorithm HACCSpatial, especially designed for this PA task. We also performed experiments using traditional ensembles approaches from the literature, evaluating their behavior to achieve consensus solutions from individual clusterings obtained from features splitting or running one of the abovementioned algorithms. Results showed some differences between FCM and HACC-Spatial, mainly for the visualization of management classes in the form of maps. Considering the consensus clusterings provided by ensembles, it became clear the attempt to achieve an agreement result that most closely matches the original clusterings, showing us some details that may go undetected when we analyse only the individual clusterings.Geoinfo 2016

Algunas observaciones sobre el desecamiento del grano de cacao bajo diferentes condiciones

Las diversas modalidades del proceso de desecamiento del cacao fermentado (con tal de que la temperatura de desecamiento no sea muy elevada) tienen escasa influencia sobre la calidad aparente del grano, a condición desde luego, de que el proceso sea llevado hasta lograr un mismo porcentaje de humedad en los granos. Ya se sabía que, aparentemente, debería preferirse el desecamiento artificial, al natural, por cuanto se logra un mejor control de la temperatura y de otras condiciones del proceso. En realidad, los fabricantes prefieren, en igualdad de condiciones, el cacao desecado al sol. A este propósito había sido establecido por la Oficina Internacional de Fabricantes de Cacao y Chocolate, según dice Knapp (ya citado), que el cacao que hubiese sido secado a más de 50°C, fuera específicamente rotulado como "desecado artificialmente". Sin embargo, el desecamiento al sol significa ordinariamente para los granos, una temperatura notoriamente superior a dichos 50oC, aunque por lo regular no suprior a 60°C

Observaciones sobre la enfermedad de la "hoja bronceada" del cocotero en venezuela.

La enfermedad de las "hojas bronceadas" del cocotero (Cocos nucifera) ha sido hallada en toda la costa de Venezuela, en las costas septentrional y meridional de la República Dominicana, y posiblemente en la costa Sur (Prov. de Oriente) de Cuba. Se describen detenidamente los síntomas de la enfermedad en Venezuela, en donde se estableció a lo menos desde los años 1910-1914, y donde hay centros de muy notable gravedad. Los síntomas de la enfermedad de Trinidad y la de Jamaica que Leach expone, fueron comparados con los de las enfermedades de Venezuela y la República Dominicana; teniendo la enfermedad de Venezuela síntomas intermediarios o en común con las de Trinidad y Jamaica; así mismo la enfermedad se parece a la de la República Dominicana, que, sin embargo, se parece más a la Jamaiquina. Nuestra conclusión provisional es que, más bien que dos enfermedades distintas, existentes ambas en Venezuela, trátase de una sola enfermedad, que sin embargo puede asumir "facies" distintas debido a las condiciones ambientales de cultivo (principalmente edáficas y climáticas). y probablemente también a factores individuales de productividad y adaptación a esas condiciones así como también a las variedades cultivadas

Integração de ferramentas de SIG e mineração de dados para utilização em atividades de gestão espacialmente diferenciada aplicada na agricultura de precisão.

A agricultura de precisão é uma abordagem agrícola que se utiliza de tecnologias da informação e comunicação para possibilitar uma gestão diferenciada da lavoura voltada para o aumento da produtividade de maneira sustentável, reduzindo os impactos ao meio ambiente a partir da aplicação espacialmente diferenciada de insumos agrícolas e consequentemente proporcionando o aumento do retorno econômico. Um dos conceitos utilizados por essa abordagem é o delineamento de unidades de gestão diferenciada, permitindo tratamentos localizados de acordo com as características do solo e das plantas. Devido ao crescimento da disponibilidade de ferramentas computacionais que podem auxiliar usuários finais, a criação de modelos e arquiteturas acessíveis e capazes de agregar essas ferramentas, de forma a possibilitar o seu uso de maneira integrada, tem se tornado intenso objeto de estudo. Este artigo descreve a proposta de uma arquitetura voltada para apoiar o processo de delineamento de unidades de gestão diferenciada em agricultura de precisão utilizando software livre e de distribuição gratuita. A arquitetura proposta é comparada com outras abordagens disponíveis na literatura, onde são identificadas as suas vantagens e desvantagens e propostas novas alternativas para trabalhos futuros. O trabalho realizado nesse artigo permitiu verificar que a solução proposta é viável para essa aplicação de AP, devido à disponibilidade das ferramentas e a utilização dos padrões OGC, amplamente disseminados nas áreas de aplicação que utilizam dados geoespaciais.SBIAgro 2017

Libri novi

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/43270/1/11046_2005_Article_BF02089882.pd

Shear-Modulus Investigations of Monohydroxy Alcohols: Evidence for a Short-Chain-Polymer Rheological Response

In addition to the ubiquitous structural relaxation of viscous supercooled liquids, monohydroxy alcohols and several other hydrogen-bonded systems display a strong single-exponential electrical low-frequency absorption. So far, this so-called Debye process could be observed only using dielectric techniques. Exploiting a combination of broad-band and high-resolution rheology experiments for three isomeric octanols, unambiguous mechanical evidence for the Debye process is found. Its spectral signature is similar to the viscoelastic fingerprint of small-chain polymers, enabling us to estimate the effective molecular weight for the supramolecular structure formed by the studied monohydroxy alcohols. This finding opens the venue for the application of further non-dielectric techniques directed at unraveling the microscopic nature of the Debye process and for an understanding of this phenomenon in terms of polymer concepts.Comment: 12 pages, 4 figure

Random, blocky and alternating ordering in supramolecular polymers of chemically bidisperse monomers

As a first step to understanding the role of molecular or chemical polydispersity in self-assembly, we put forward a coarse-grained model that describes the spontaneous formation of quasi-linear polymers in solutions containing two self-assembling species. Our theoretical framework is based on a two-component self-assembled Ising model in which the bidispersity is parameterized in terms of the strengths of the binding free energies that depend on the monomer species involved in the pairing interaction. Depending upon the relative values of the binding free energies involved, different morphologies of assemblies that include both components are formed, exhibiting paramagnetic-, ferromagnetic- or anti ferromagnetic-like order,i.e., random, blocky or alternating ordering of the two components in the assemblies. Analyzing the model for the case of ferromagnetic ordering, which is of most practical interest, we find that the transition from conditions of minimal assembly to those characterized by strong polymerization can be described by a critical concentration that depends on the concentration ratio of the two species. Interestingly, the distribution of monomers in the assemblies is different from that in the original distribution, i.e., the ratio of the concentrations of the two components put into the system. The monomers with a smaller binding free energy are more abundant in short assemblies and monomers with a larger binding affinity are more abundant in longer assemblies. Under certain conditions the two components congregate into separate supramolecular polymeric species and in that sense phase separate. We find strong deviations from the expected growth law for supramolecular polymers even for modest amounts of a second component, provided it is chemically sufficiently distinct from the main one.Comment: Submitted to Macromolecules, 6 figures. arXiv admin note: substantial text overlap with arXiv:1111.176

Molecular architecture and assembly of the yeast kinetochore MIND complex

MIND–Mis12 bridges the microtubule receptor complex and the inner kinetochore (see also a related paper by Petrovic et al. in this issue)

Self-assembly in solution of a reversible comb-shaped supramolecular polymer

We report a single step synthesis of a polyisobutene with a bis-urea moiety in the middle of the chain. In low polarity solvents, this polymer self-assembles by hydrogen bonding to form a combshaped polymer with a central hydrogen bonded backbone and polyisobutene arms. The comb backbone can be reversibly broken, and consequently, its length can be tuned by changing the solvent, the concentration or the temperature. Moreover, we have proved that the bulkiness of the side-chains have a strong influence on both the self-assembly pattern and the length of the backbone. Finally, the density of arms can be reduced, by simply mixing with a low molar mass bis-urea