Applications of the Ashtekar gravity to four dimensional hyperk\"ahler geometry and Yang-Mills Instantons

The Ashtekar-Mason-Newman equations are used to construct the hyperk\"ahler metrics on four dimensional manifolds. These equations are closely related to anti self-dual Yang-Mills equations of the infinite dimensional gauge Lie algebras of all volume preserving vector fields. Several examples of hyperk\"ahler metrics are presented through the reductions of anti self-dual connections. For any gauge group anti self-dual connections on hyperk\"ahler manifolds are constructed using the solutions of both Nahm and Laplace equations.Comment: 9pages, Figures are not include

Modelado de sistemas supervisores distribuidos y abiertos usando redes de Petri y orientación a Objetos

El modelado de sistemas supervisores para ambientes automatizados puede ser visto como una tarea que involucra técnicas y métodos de dos áreas principales: ingeniería de control e ingeniería de software. En este contexto, el propósito de este trabajo es introducir un nuevo abordaje para el modelado de sistemas supervisores distribuidos y abiertos, basado en la unión de técnicas tradicionales de ingeniería de software (como la orientación a objetos) y con modelos formales de los sistemas dinámicos a eventos discretos (como las redes de Petri). En el primer nivel de abstracción, es usado el modelo de referencia de procesamiento distribuido y abierto (RM-ODP) como marco atquitectural estándar pata la construcción de un sistema distribuido y abierto. Basado en el modelo de referencia ODP, los diagramas en el lenguaje de modelado unificado UML son construidos como un segundo nivel de abstracción. Finalmente, las redes de Petri (el tercer nivel de abstracción) son usadas a través del proceso con la finalidad de garantizar la coherencia entre los modelos en UML desde el análisis de requerimientos hasta la implementación de manera a proveer modelos formales del sistema

Protein processing characterized by a gel-free proteomics approach

We describe a method for the specific isolation of representative N-terminal peptides of proteins and their proteolytic fragments. Their isolation is based on a gel-free, peptidecentric proteomics approach using the principle of diagonal chromatography. We will indicate that the introduction of an altered chemical property to internal peptides holding a free α-N-terminus results in altered column retention of these peptides, thereby enabling the isolation and further characterization by mass spectrometry of N-terminal peptides. Besides pointing to changes in protein expression levels when performing such proteome surveys in a differential modus, protease specificity and substrate repertoires can be allocated since both are specified by neo-N-termini generated after a protease cleavage event. As such, our gel-free proteomics technology is widely applicable and amenable for a variety of proteome-driven protease degradomics research

Ultrafine-scale magnetostratigraphy of marine ferromanganese crust

http://geology.geoscienceworld.org/content/39/3/227.full.pdf+htmlHydrogenetic ferromanganese crusts are iron-manganese oxide chemical precipitates on the seafloor that grow over periods of tens of millions of years. Their secular records of chemical, mineralogical, and textural variations are archives of deep-sea environmental changes. However, environmental reconstruction requires reliable high-resolution age dating. Earlier chronological methods using radiochemical and stable isotopes provided age models for ferromanganese crusts, but have limitations on the millimeter scale. For example, the reliability of 10Be/9Be chronometry, commonly considered the most reliable technique, depends on the assumption that the production and preservation of 10Be are constant, and requires accurate knowledge of the 10Be half-life. To overcome these limitations, we applied an alternative chronometric technique, magnetostratigraphy, to a 50-mm-thick hydrogenetic ferromanganese crust (D96-m4) from the northwest Pacific. Submillimeter-scale magnetic stripes originating from approximately oppositely magnetized regions oriented parallel to bedding were clearly recognized on thin sections of the crust using a high-resolution magnetometry technique called scanning SQUID (superconducting quantum interference device) microscopy. By correlating the boundaries of the magnetic stripes with known geomagnetic reversals, we determined an average growth rate of 5.1 ± 0.2 mm/m.y., which is within 16% of that deduced from the 10Be/9Be method (6.0 ± 0.2 mm/m.y.). This is the finest-scale magnetostratigraphic study of a geologic sample to date. Ultrafine-scale magnetostratigraphy using SQUID microscopy is a powerful new chronological tool for estimating ages and growth rates for hydrogenetic ferromanganese crusts. It provides chronological constraints with the accuracy promised by the astronomically calibrated magnetostratigraphic time scale (1–40 k.y.).Japan Society for the Promotion of Science (Grant-in-Aid for Scientific Research (21654071))National Science Foundation (U.S.) (Collaboration in Mathematical Geosciences Program

Multiple factor analysis to identify correlated variable among microclimate, thermal comfort and infrared thermography in agroforestry systems.

Goal was to use the Multiple Factor Analysis to reduce dimensionality of variables, to identify groups of correlated variables and to obtain a common assessment tool to evaluate microclimate, thermal comfort and infrared thermography in agroforestry systems. The experiment was conducted at the Embrapa Beef Cattle, Campo Grande, MS, from July 2015 to February 2016, corresponding to winter and summer seasons, in two agroforestry systems with different tree densities and spatial arrangements of native and planted trees. Readings were made from 8:00 a.m. to 4:00 p.m., for microclimate parameters (air temperature, dew point temperature, black globe temperature, relative humidity, wind speed, global solar radiation, photosynthetically active radiation and luminosity), thermal comfort (Temperature and Humidity Index, Black Globe and Humidity Index, Radiation Thermal Load), and infrared thermography (temperature and humidity of tree crown and soil surface), under full sun and shadow projection. Multiple Factor Analysis found three Synthetic Analytical Dimensions that explained 55.5% of the total observed variance. Strong and positive associations between infrared thermography, microclimate, thermal comfort and radiation were found. Thus, it is suggested that infrared thermography is a potential tool to be used for microclimate prediction and thermal comfort under agroforestry systems

Dipole-quadrupole interactions and the nature of phase III of compressed hydrogen

A new class of strongly infrared active structures is identified for phase III of compressed molecular H2 by constant-pressure ab initio molecular dynamics and density-functional perturbation calculations. These are planar quadrupolar structures obtained as a distortion of low-pressure quadrupolar phases, after they become unstable at about 150 GPa due to a zone-boundary soft phonon. The nature of the II-III transition and the origin of the IR activity are rationalized by means of simple electrostatics, as the onset of a stabilizing dipole-quadrupole interaction.Comment: 4 pages, 3 figures. To appear in Phys. Rev. Let

Evidence that histidine protonation of receptor-bound anthrax protective antigen is a trigger for pore formation

The protective antigen (PA) component of the anthrax toxin forms pores within the low pH environment of host endosomes, through mechanisms that are poorly understood. It has been proposed that pore formation is dependent on histidine protonation. In previous work, we biosynthetically incorporated 2-fluorohistidine (2-FHis), an isosteric analog of histidine with a significantly reduced pKa (~1), into PA, and showed that the pH-dependent conversion from the soluble prepore to a pore was unchanged. However, we also observed that 2-FHisPA was non-functional in the ability to mediate cytotoxicity of CHO-K1 cells by LFN-DTA, and was defective in translocation through planar lipid bilayers. Here, we show that the defect in cytotoxicity is due to both a defect in translocation and, when bound to the host cellular receptor, an inability to undergo low pH-induced pore formation. Combining X-ray crystallography with hydrogen-deuterium (H-D) exchange mass spectrometry, our studies lead to a model in which hydrogen bonds to the histidine ring are strengthened by receptor binding. The combination of both fluorination and receptor binding is sufficient to block low pH-induced pore formation

Avaliação das silagens de quatro cultivares de sorgo sob três doses de nitrogênio. I. características fermentativas e densidades da silagem, produção de gases e efluentes.

O trabalho teve como objetivo avaliar as características fermentativas, as densidades no momento de enchimento (Den) e da abertura dos silos (Dab), produção de gás e efluentes (EfI) da silagem de quatro cultivares de sorgo forrageiro sob doses crescentes de nitrogênio. Decorridos 111 dias de crescimento vegetativo, procedeu-se o corte e ensilagem dos híbridos no estágio pastoso tendendo para o farináceo. Como silos experimentais foram utilizados baldes plásticos (mini-silos) com capacidade para 15 litros. Os silos foram abertos em 10/05/2005, retirando-se uma sub-amostra de 500 g para extração do suco da silagem para determinação do pH e os ácidos graxos voláteis. Para o ácido acético as cultivares e tratamentos não diferiram (P>0.05), exceto para a cultivar BR 700, que diferiu (P0,05) entre os tratamentos e cultivares. O ácido lático diferiu (PO,05) para Den, Dab e Gas, exceto para EfI que apresentou diferença (P>0,05). Entre os tratamentos (60 e 120 kg/ha de N) apenas a cultivar 0369 255 diferiu das demais (PO,05)

Composição químico-bromatológica de quatro cultivares de sorgo submetidos a três doses de nitrogênio.

O presente trabalho teve como objetivo avaliar a composição químico-bromatológica de quatro cultivares de sorgo forrageiro submetidos a três doses crescentes de nitrogênio (O, 60 e 120 kg/ha). O delineamento utilizado foi o blocos casualizados em esquema fatorial 4x3, sendo quatro cultivares e três doses de nitrogênio, com quatro repetições. Não ocorreu diferença significativa (P>O,05) para os teores de FDN e FDA entre os híbridos no primeiro e no segundo corte. O híbrido 1F305 apresentou diferença significativa (P0.05)

Determinação dos teores de proteína bruta e da digestibilidade "in vitro" da matéria seca da silagem de híbridos de sorgo forrageiro adubados com doses crescentes de nitrogênio.

O objetivo do trabalho foi avaliar o teor de proteína bruta (PB) e a digestíbilidade "in vítro" da matéria seca (DIVMS) da silagem de quatro híbridos de sorgo forrageiro adubados com doses crescentes de nitrogênio (O, 60 e 120 kg/ha de N). Foram utilizados baldes plásticos com capacidade para 15 litros como silos experimentais. A forragem foi triturada em partículas de 1 cm e compactada com os pés a medida que se formavam camadas de cinco a dez centímetros para obter maior uniformidade. Foi retirado uma sub-amostra de aproximadamente 5OO g, levada à estufa de ventilação forçada (65°C) e posteriormente moída em peneira de 1 mm para a determinação da PB e da DIVMS. O teor de PB variou (P0,05) entre as cultivares e os tratamentos