QPCR analysis of functional genes in iron-rich microbial mats at an active hydrothermal vent system Loihi Seamount, Hawaii

The recently discovered Zetaproteobacteria represent a novel class of Proteobacteria which oxidize Fe(II) to Fe(III), driving CO2 fixation at hydrothermal vents. These chemolithoautotrophs are the dominant bacterial population in iron-rich microbial mats, and represent a unique opportunity to investigate the connection between deep-sea geochemical processes and the dark microbial world. Zetaproteobacteria were first discovered at Loihi Seamount, located 35 km southeast off the big island of Hawaii and characterized by low-temperature diffuse hydrothermal venting. These vents are surrounded by luxuriant, iron-rich microbial mats that are colonized and often dominated by Zetaproteobacteria. Five novel non-degenerate QPCR assays were designed using sequence data derived from microbial iron-mat samples collected at Loihi in March 2013. Genes of interest were nifH, nirK, and arsC, associated with microbial nitrogen fixation, denitrification and arsenic detoxification, respectively. We also examined carbon fixation genes cbbM and aclB, which are indicators for the Calvin Benson Bassham (CBB) and reductive tricarboxylic acid (rTCA) cycles, respectively. All functional genes were found to be present at Loihi Seamount with the exception of nifH, which was undetectable with our method. Functional genes arsC and nirK were detected in all samples assayed, indicating that both arsenic detoxification and denitrification processes are likely occurring across all hydrothermal mat habitats. cbbM and aclB were also detectable in all samples assayed, indicating the co-occurence of these two modes of carbon fixation. T-RFLP analysis indicates that the communities in iron-rch mat samples collected in 2013 are very similar to one another. T-RFLP Group 1 had high Zetaproteobacteria abundance and low aclB relative to cbbM, indicating that the CBB cycle is the major mode of carbon fixation in Zetaproteobacteria-rich mat communities. T-RFLP Group 2 had low Zetaproteobacteria abundance and high aclB gene copy numbers, suggesting that the rTCA cycle is operating in non-Zetaproteobacteria taxa and plays an important role in carbon fixation in these communities. Based on these results, we conclude that aclB may be an important functional gene indicator of community composition. QPCR variance was explained by mat morphology but not temperature or sample site. Gene aclB was significantly associated with mat morphology, and may contribute to the significant relationship between the QPCR data and mat type. Fe(II) was significant with mat morphology. Geochemistry data was significantly associated with sample site and mat morphology, indicating that there is a range of chemistries in which these iron-rich microbial communities can thrive, and/or that the abundance of functional genes in these mat communities changes gradually in response to more dynamic chemical variation over time. Together, these QPCR assays constitute a ‘functional gene signature’ for iron mat samples across a broad array of temperatures, mat types, chemistries, and sampling sites in and around Pele’s Pit at Loihi Seamount

The Changing Traditional Value System of the Dakota Indian: A Study of the Conflicting Value Systems of the Dakota Indian and Western Civilization

One of the conclusions of anthropologists is that of cultural variability and the relativity of value systems. This means that the designs for living with its system of moral values which one society has evolved may differ considerably from those of another. Each society has their unique value system (moral code). The Dakota Indians have (or had) theirs and the people of Western civilization have theirs. As a result of the culture contact of these two groups over the past seventy-five years, the Dakota Indian has been exposed to, even coerced to follow, a value system different than his own. The purpose of this study is to describe and analyze the traditional value system of the Dakota Indians in contrast to that of Western civilization, and, as a result of the conflict of value systems between the two societies, to discover any symptoms of social or personal disorganization which may accrue to the present day Pine Ridge Reservation resident

The Dakota Indian Religion, A Study of Conflict in Values

Religious beliefs have exerted substantial influence on the values of the Dakota Indians. In earlier days religious folklore infused every area of their daily lives. When the missionaries introduced Chnstianity to the tribes on the Great Plains, important changes began to take place. Values which conflicted with customary beliefs were interposed, but many of the traditional values were retained. In some cases, accommodation of conflicting values was attempted in marginal religious activities which combined elements of both the old and new religions. In other cases, the conflicts appeared insurmountable, and some individuals sought escape or succumbed to apathy. A study of the present day values of these people requires some understanding of their traditional religion. Thus, Part II of this bulletin is designed to provide a systematic analysis of the religious background of the Dakota Indians. Here are some of the myths and legends, and the beliefs, practices, and ritual which dominated Dakota thinking at the time of initial contact with the Christian missionaries. In Part III the subsequent changes in Dakota values are discussed and analysed in historical perspective and in terms of the value conflicts which have resulted from the contact of these two different culture patterns. Statistical evidence from a study of two communities on the Pine Ridge Reservation is presented to support the cultural conflict thesis. Implications of the study are suggested in Part IV

TEM observations of crack tip: cavity interactions

Crack tip-cavity interactions have been studied by performing room temperature deformation experiments in a transmission electron microscope on ion-irradiated type 316 stainless steel with small helium containing cavities. Slip dislocations emitted from a crack tip cut, sheared, and thereby elongated cavities without a volume enlargement. As the crack tip approached, a cavity volume enlargement occurred. Instead of the cavities continuing to enlarge until they touch, the walls between the cavities fractured. Fracture surface dimples do not correlate in size or density with these enlarged cavities

Misfit-dislocation generation by dissociated dislocations in quantum-well heterostructures

The mechanisms whereby 60° misfit dislocations are generated from dissociated threading dislocations in quantum-well heterostructures are considered. The two partial dislocations experience different misfit stresses, resulting in each partial having a different critical thickness. As a consequence, a number of different dislocation configurations are predicted, including the possibility of producing stacking faults of infinite width. © 1994 The American Physical Societ

A comparative study of hysteresis band PWM techniques for current control in shunt active power filters

El presente artículo evalúa el desempeño de un filtro activo empleando tres diferentes técnicas de control de corriente de banda de histéresis: banda fija, banda adaptativa y con modulación por vector espacial. En la comparación se estudian las características de cada técnica y mediante simulación se evalúa su desempeño y operación. En todos los casos se emplea la teoría pq para el cálculo de las corrientes de referencia y se emplea un controlador proporcional para regular la tensión del bus de continua. De acuerdo con los resultados, las técnicas PWM evaluadas permiten una reducción del contenido armónico de la corriente de la red de alimentación de 31 % sin compensación, a un 6 %, considerando el filtro activo de potencia. La técnica de banda adaptativa de histéresis presenta el más bajo desempeño en la reducción de armónicos en las corrientes de la red. Además, se tiene que el método de banda fija de histéresis es el más recomendado para aplicaciones de filtros paralelo debido a que posee una estructura más simple que permite su implementación. Los resultados tambien muestran que la técnica de banda adaptativa de histéresis es la que presenta mayor reducción en las variaciones de la frecuencia de conmutación, requiriendo mayor número de operaciones, ya que requiere calcular el ancho de banda en cada iteración. Mientras que la técnica de modulación por vector espacial y banda de histéresis presenta frecuencias de conmutación altamente variables y mayor complejidad en su implementación.This paper evaluates the performance of an active power filter using three hysteresis band current control techniques: fixed-band, adaptive-band, and Space Vector Modulation. The characteristics of each method, along with their behaviour under different operating conditions, are studied by means of time domain simulations. The pq theory is used in all the cases to calculate the current reference, and a proportional controller is implemented to regulate the voltage in the dc bus. Based on the results, the PWM techniques evaluated in this work enable a reduction in the harmonic content of the supply grid currents that ranges from 31% without compensation to 6% after the active power filter is connected. The adaptive hysteresis band method exhibited the worst performance in the elimination of harmonics in grid currents; furthermore, it presented the largest reduction of variations in the switching frequency and requires more calculation time because the band width must be computed at each iteration. In turn, the fixed hysteresis band alternative is the most widely recommended for applications that involve parallel filters because it has a simpler structure that enables its implementation. Finally, the technique that combines space vector modulation and hysteresis band current control produced highly-variable switching frequencies and a more complex implementation

Parameter estimation for an electric arc furnace model using maximum likelihood

Este documento presenta una metodología para determinar los parámetros de un modelo de un horno de arco eléctrico usando máxima verosimilitud (máximum likelihood estimation - MLE). La estimación por máxima verosimilitud es uno de los métodos de estimación de parámetros clásica más empleada en la práctica. El modelo de horno de arco utilizado considera las variaciones aperiódicas y la no linealidad en su característica voltaje-corriente. Se ha utilizado el toolbox NETLAB desarrollado para MATLAB®, para solucionar el sistema de ecuaciones no lineales que relacionan los parámetros del modelo que se requieren estimar. Los resultados obtenidos en simulación del modelo del horno de arco implementado en PSCADTM, se comparan con mediciones reales tomadas en la etapa más crítica de la operación del horno. Se muestra como el modelo del horno de arco captura con gran detalle las formas de onda de voltajes y corrientes reales de los arcos eléctricos generados al interior del horno. Los resultados obtenidos muestran un error máximo de 5,03 % en las corrientes eficaces del arco eléctrico y 11,4 % en los voltajes eficaces de fase del secundario del transformador que energiza los electrodos del horno.In this paper, we present a methodology for estimating the parameters of a model for an electrical arc furnace, by using maximum likelihood estimation. Maximum likelihood estimation is one of the most employed methods for parameter estimation in practical settings. The model for the electrical arc furnace that we consider, takes into account the non-periodic and non-linear variations in the voltage-current characteristic. We use NETLAB, an open source MATLAB® toolbox, for solving a set of non-linear algebraic equations that relate all the parameters to be estimated. Results obtained through simulation of the model in PSCADTM, are contrasted against real measurements taken during the furnance's most critical operating point. We show how the model for the electrical arc furnace, with appropriate parameter tuning, captures with great detail the real voltage and current waveforms generated by the system. Results obtained show a maximum error of 5% for the current's root mean square error

Clustering of Vibrio parahaemolyticus Isolates Using MLST and Whole-Genome Phylogenetics and Protein Motif Fingerprinting

Vibrio parahaemolyticus is a ubiquitous and abundant member of native microbial assemblages in coastal waters and shellfish. Though V. parahaemolyticus is predominantly environmental, some strains have infected human hosts and caused outbreaks of seafood-related gastroenteritis. In order to understand differences among clinical and environmental V. parahaemolyticus strains, we used high quality DNA sequencing data to compare the genomes of V. parahaemolyticus isolates (n = 43) from a variety of geographic locations and clinical and environmental sample matrices. We used phylogenetic trees inferred from multilocus sequence typing (MLST) and whole-genome (WG) alignments, as well as a novel classification and genome clustering approach that relies on protein motif fingerprints (MFs), to assess relationships between V. parahaemolyticus strains and identify novel molecular targets associated with virulence. Differences in strain clustering at more than one position were observed between the MLST and WG phylogenetic trees. The WG phylogeny had higher support values and strain resolution since isolates of the same sequence type could be differentiated. The MF analysis revealed groups of protein motifs that were associated with the pathogenic MLST type ST36 and a large group of clinical strains isolated from human stool. A subset of the stool and ST36-associated protein motifs were selected for further analysis and the motif sequences were found in genes with a variety of functions, including transposases, secretion system components and effectors, and hypothetical proteins. DNA sequences associated with these protein motifs are candidate targets for future molecular assays in order to improve surveys of pathogenic V. parahaemolyticus in the environment and seafood

TiNiSn: A gateway to the (1,1,1) intermetallic compounds

Recent awareness of the transport properties of Skutterudite pnictides has stimulated an interest in numerous other intermetallic compounds having a gap in the density of states at the Fermi level including the MNiSn compounds where M = (Ti, Zr, Hf). These intermetallic half-Heusler compounds are characterized by high Seebeck coefficients ({minus}150 to {minus}300 {micro}V/deg.) and reasonable carrier mobilities (30 to 50 cm{sup 2}/V-s) at room temperature which make them attractive candidates for intermediate temperature thermoelectric applications. Samples of TiNiSn were prepared by arc melting and homogenized by heat treatment. The temperature dependence of the electrical resistivity, Seebeck coefficient, and thermal diffusivity of these samples was characterized between 22 C and 900 C. The electrical resistivity and thermopower both decrease with temperature although the resistivity decreases at a faster rate. Electrical power factors in excess of 25 {micro}W/cm-C{sup 2} were observed in nearly single phase alloys within a 300 to 600 C temperature range. A brief survey of other selected ternary intermetallic compounds is also presented

Joint profiling of DNA methylation and chromatin architecture in single cells.

We report a molecular assay, Methyl-HiC, that can simultaneously capture the chromosome conformation and DNA methylome in a cell. Methyl-HiC reveals coordinated DNA methylation status between distal genomic segments that are in spatial proximity in the nucleus, and delineates heterogeneity of both the chromatin architecture and DNA methylome in a mixed population. It enables simultaneous characterization of cell-type-specific chromatin organization and epigenome in complex tissues