On geometry-dependent vortex stability and topological spin excitations on curved surfaces with cylindrical symmetry

We study the Heisenberg Model on cylindrically symmetric curved surfaces. Two kinds of excitations are considered. The first is given by the isotropic regime, yielding the sine-Gordon equation and $\pi$-solitons are predicted. The second one is given by the XY model, leading to a vortex turning around the surface. Helical states are also considered, however, topological arguments can not be used to ensure its stability. The energy and the anisotropy parameter which stabilizes the vortex state are explicitly calculated for two surfaces: catenoid and hyperboloid. The results show that the anisotropy and the vortex energy depends on the underlying geometry.Comment: 10 pages, 2 figures, Accepted for publication in Phys. Lett A (2013

Two infrared Yang-Mills solutions in stochastic quantization and in an effective action formalism

Three decades of work on the quantum field equations of pure Yang-Mills theory have distilled two families of solutions in Landau gauge. Both coincide for high (Euclidean) momentum with known perturbation theory, and both predict an infrared suppressed transverse gluon propagator, but whereas the solution known as "scaling" features an infrared power law for the gluon and ghost propagators, the "massive" solution rather describes the gluon as a vector boson that features a finite Debye screening mass. In this work we examine the gauge dependence of these solutions by adopting stochastic quantization. What we find, in four dimensions and in a rainbow approximation, is that stochastic quantization supports both solutions in Landau gauge but the scaling solution abruptly disappears when the parameter controlling the drift force is separated from zero (soft gauge-fixing), recovering only the perturbative propagators; the massive solution seems to survive the extension outside Landau gauge. These results are consistent with the scaling solution being related to the existence of a Gribov horizon, with the massive one being more general. We also examine the effective action in Faddeev-Popov quantization that generates the rainbow and we find, for a bare vertex approximation, that the the massive-type solutions minimise the quantum effective action.Comment: 13 pages, 7 figures. Change of title to reflect version accepted for publicatio

Nanoparticles as vectors of other contaminants in estuarine suspended sediments: Natural and real conditions

Studding the behaviour and danger of nanoparticles (NPs, minerals and amorphous phases) in the estuarine ecosystem is presently incomplete by the lack of measureable description of NPs in the ecological conditions, such as suspended-sediments (SS). In the last years, several works have revealed the toxic consequences of ultra-fine and nanoparticulate compounds on diverse systems, raising apprehensions over the nanocontaminants behaviour and destiny in the numerous ecological partitions. The general objective of the manuscript is to explain the geochemical conditions of the LES (Laguna estuarine system, southern Brazil) suspended sediments covering an area around the main South American coal plant, enhancing the creation of future public policies for environmental recovery projects. Subsequently the discharge of nanoparticles and toxic element (TE) in the ecosystem, NPs react with several constituents of the nature and suffers active alteration progressions. Contamination coming from engineering actions, wastewater, are something identifiable, however when these contaminations are accompanied by other contamination sources (e.g. mining and farming) the work gets defaulted. By combining material about the concentration of TE contaminants and NPs occurrences, this work offers novel visions into contaminant contact and the possible effects of such exposure on estuarine systems in Brazil. The results presented here will be useful for different areas of estuaries around the world

Environmental aspects of the depreciation of the culturally significant Wall of Cartagena de Indias – Colombia

Among the diverse archeological relics of the past, the Cartagena de Indias Wall is one of the greatest representations of European cultural architecture in South America. To assess the implication of contamination on the depreciation of the culturally significant Wall of Cartagena de Indias - Colombia, a detailed, multi-analytical approach was conducted on components of the wall. Accumulated ultra-fine particles (UFPs) and superficial nano-particles (NPs) containing hazardous elements (HEs) on the wall were identified in an attempt to understand whether atmospheric pollution is hastening the depreciation of the structure itself. Mortar which at one point held the stones together is now weak and has fallen away in places. Irreparable damage is being done by salt spray, acid rain and the site's tropical humid climate. Several HEs and organic compounds found within the local environment are also contributing to the gradual deterioration of the construction. In this study, advanced microscopy analyses have been applied to understand the properties of UFPs and NPs deposited onto the wall's weathered external walls through exposure to atmospheric pollution. Several materials identified by X-Ray Diffraction (XRD) can be detected using high-resolution transmission electron microscopy (HR-TEM) and field emission scanning electron microscope (FE-SEM). The presence of anglesite, gypsum, hematite containing HEs, and several organic compounds modified due to moisture and contamination was found. Black crusts located on the structure could potentially serve as a source of HEs pollution and a probable hazard to not only to the ecosystem but also to human health

Foraging Activity of Xylocopa cearensis (Ducke) in Sand Dune Landscape

Bees foraging strategy is affected by the distribution and abundance of flower resources, mainly nectar and pollen. Homing-time of female Xylocopa cearensis (Ducke) bees to their nests was assessed through a simple translocation method. The hypothesis addressed was that resource distribution in the landscape level influences bee homing time. The study area comprises about 300ha in a sand dune field with patchy shrubs in Salvador, Bahia, Brazil. The mean homing time after translocation was 60 min (sd = 4.36 min; n= 03), except for one bee that did not returned. The translocation technique was successfully applied to large solitary bees, since they do return to their own nest and can be easily recognized when arriving. Also, bees returned carrying pollen, what suggests foraging activity after translocations. Results evidence landscape functional connectivity since bees were able to move through local habitats. Further studies should address movement cost tradeoffs and its consequences on bee diversity conservation

Nanoparticles from evaporite materials in Colombian coal mine drainages

Ultrathin and nanometric materials (minerals and amorphous phases) are detected in transitory deposits of potential hazardous elements (PHEs), especially in acidic coal mine drainages. The main goal of this work was to evaluate the occurrence of PHEs in nanoparticles (NPs) in evaporative structures in coal mining areas with high concentrations of PHEs. The precipitates were sampled in several coal mining areas in Colombia, with the purpose of evaluating the geochemical and environmental structures. In the present work, to better diagnose areas affected by coal mining, an innovative analytical procedure is proposed to define the association between PHEs in mine drainage sediments. The procedure includes the analytical study with X-Ray Diffraction (XRD) and advanced electron microscopy, before and after a series of sequential extractions to separate amorphous, magnetic, and crystalline compounds. Of the three main types of precipitates identified, the yellowish precipitates had the highest amounts of PHEs while the white precipitates had only small amounts of PHEs and the greenish precipitates contained TiO2 nanoparticles. The results from this study will be usable for more than fifty countries that have coal mine drainages

Nanoparticles in fossil and mineral fuel sectors and their impact on environment and human health: A review and perspective

Nanoscience and technology have enabled better insights into the environmental and health impacts arising from the mining, production and use of fossil and mineral fuels. Here we provide an overview of the nanoscience-based applications and discoveries concerning coal and mineral fuel (i.e., uranium-containing minerals) mining, refining/production, use, and disposal of wastes. These processes result in massive nanoparticle release and secondary nanoparticle generation which have highly significant environmental implications and human health consequences on local, regional, and even global levels. Until recently, very little was known about nanoparticle fractions. Recent advancements and sophistications enable us to detect, collect and study these materials which are roughly 1 nm (0.001 µm) up to several tens of nanometers in size. These materials are known to behave differently (chemically, electrically, and mechanically), relative to their macroscopic equivalents. This is what makes nanoscience fascinating and difficult to predict, underscoring the importance of this emerging new field. For example, nanoparticles associated with coal and mineral fuel influence the release, uptake, and transportation of hazardous elements associated with mining, processing, and waste storage in the surrounding areas. This includes long distance transport down streams, rivers, and eventually to oceans such as from coal and uranium mine drainages. In terms of human health, in all phases of mining, production/refining, use, and waste disposal, the associated nanoparticles can be acquired through oral ingestion, inhalation, and dermal absorption. Inhalation has been shown to be particularly damaging, where lung, heart, kidney, and brain diseases are prevalent. Relative to all other fields of science and engineering associated with coal and mineral fuel mining, production, use, and clean-up efforts, nanoscience, although a much newer field then the rest by comparison, is still greatly under-represented and under-utilized. There is also a continuing gap between what we so far know about the behavior of nanoparticles, and what remains to be discovered

SIMBA: a web tool for managing bacterial genome assembly generated by Ion PGM sequencing technology

Background The evolution of Next-Generation Sequencing (NGS) has considerably reduced the cost per sequenced-base, allowing a significant rise of sequencing projects, mainly in prokaryotes. However, the range of available NGS platforms requires different strategies and software to correctly assemble genomes. Different strategies are necessary to properly complete an assembly project, in addition to the installation or modification of various software. This requires users to have significant expertise in these software and command line scripting experience on Unix platforms, besides possessing the basic expertise on methodologies and techniques for genome assembly. These difficulties often delay the complete genome assembly projects. Results In order to overcome this, we developed SIMBA (SImple Manager for Bacterial Assemblies), a freely available web tool that integrates several component tools for assembling and finishing bacterial genomes. SIMBA provides a friendly and intuitive user interface so bioinformaticians, even with low computational expertise, can work under a centralized administrative control system of assemblies managed by the assembly center head. SIMBA guides the users to execute assembly process through simple and interactive pages. SIMBA workflow was divided in three modules: (i) projects: allows a general vision of genome sequencing projects, in addition to data quality analysis and data format conversions; (ii) assemblies: allows de novo assemblies with the software Mira, Minia, Newbler and SPAdes, also assembly quality validations using QUAST software; and (iii) curation: presents methods to finishing assemblies through tools for scaffolding contigs and close gaps. We also presented a case study that validated the efficacy of SIMBA to manage bacterial assemblies projects sequenced using Ion Torrent PGM. Conclusion Besides to be a web tool for genome assembly, SIMBA is a complete genome assemblies project management system, which can be useful for managing of several projects in laboratories. SIMBA source code is available to download and install in local webservers at http://ufmg-simba.sourceforge.net

Tanystropheid archosauromorphs in the Lower Triassic of Gondwana

Tanystropheidae is a clade of early archosauromorphs with a reported distribution ranging from the Early to the Late Triassic of Asia, Europe, and North America. Although some specimens with possible tanystropheid affinities from the Lower Triassic beds of Brazil have been previously attributed to “Protorosauria”, little is known about the tanystropheid record in Gondwana. Here, two new and one previously reported specimen from the Sanga do Cabral Formation (Induan–Olenekian) of Brazil are described and interpreted as ?Tanystropheidae. These records, together with other tetrapods previously reported for the Sanga do Cabral Formation, increase the knowledge of the biotic diversification during the beginning of the Triassic. This contribution reinforces that the archosauromorph diversification occurred shortly after the Permo-Triassic extinction, making the Sanga do Cabral Formation an important unit for the study of early Mesozoic faunas