The Upper Proterozoic Redstone Copper Belt, Mackenzie Mountains, Nwt

The Redstone Copper Belt is a 300 km arcuate zone of late Proterozoic stratabound copper occurrences within the Coates Lake Group (proposed) in the Mackenzie Mountains, N.W.T., Canada. The Coates Lake Group was deposited on the eroded surface of shallow marine carbonates and tholeiitic basalts at the top of the Little Dal Group. Six main areas of deposition and preservation were controlled by growth faults during the early part of the Hayhook extensional tectonism (About 750 Ma).;Three formations within the Coates Lake Group record transgression from alluvial fan to sabkha and shallow platformal marine conditions (Thundercloud Formation, proposed); regression from restricted marine, lagoonal or lacustrine evaporite accumulation to alluvial carbonate sedimentation (Redstone River Formation); a transgression to low energy sabkha conditions (Transition Zone); then submergence to carbonate turbidite and mass-flow deposition below wave base (Coppercap Formation). Most of the lastic material was locally derived from underlying platformal carbonates of the Little Dal Group.;Stratabound occurrences of disseminated copper sulphide minerals are mainly in the Transition Zone between the Redstone River and Coppercap Formation. Sabkha conditions during copper deposition are shown by evaporites, cryptalgal laminites, red beds, ripple marks and desiccation cracks. Syngenetic to late diagenetic ages of mineralization are documented by step-wise upward-decreasing copper:iron ratios, stratigraphy, and association of copper sulphide minerals with sedimentary pores and diagenetic replacement textures. Active faults and coastal morphology appear to have controlled mineralization in a different way in each depositional embayment.;Anomalously abundant copper at the start of the Hayhook Orogeny could have been caused by any or all of the following: rifting with concommitant exhalative activity; leaching of underlying formations; and/or compactional dewatering of underlying formations. A limited number of chemical analyses suggest caution in interpreting the Little Dal basalts as a direct source of copper. The local genesis of the copper beds at Coates Lake is tentatively explained as follows. Copper was concentrated by evaporation in a depositional embayment, its solubility enhanced by chloride complexing. Copper sulphide minerals were diagenetically added to H(,2)S-rich algal limestones by downward and landward moving cupriferous saline waters at the start of slow marine transgression

New directions for JRST

No Abstract.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/64571/1/20360_ftp.pd

1971 - First Black SBA Officer, Wilson C. Jefferson Jr.

Photograph of Wilson C. Jefferson Jr. from the 1972 Colonial Echo. During the 1971/1972 academic year, Jefferson serves as the first Black Student Bar Association Vice-President. When he graduates in 1972, Jefferson becomes only the second Black graduate of William & Mary Law School.https://scholarship.law.wm.edu/blackhistorywmls/1001/thumbnail.jp

Enactivism and Robotic Language Acquisition: A Report from the Frontier

In this article, I assess an existing language acquisition architecture, which was deployed in linguistically unconstrained human–robot interaction, together with experimental design decisions with regard to their enactivist credentials. Despite initial scepticism with respect to enactivism’s applicability to the social domain, the introduction of the notion of participatory sense-making in the more recent enactive literature extends the framework’s reach to encompass this domain. With some exceptions, both our architecture and form of experimentation appear to be largely compatible with enactivist tenets. I analyse the architecture and design decisions along the five enactivist core themes of autonomy, embodiment, emergence, sense-making, and experience, and discuss the role of affect due to its central role within our acquisition experiments. In conclusion, I join some enactivists in demanding that interaction is taken seriously as an irreducible and independent subject of scientific investigation, and go further by hypothesising its potential value to machine learning.Peer reviewedFinal Published versio

Early Surgery for Traumatic Spinal Cord Injury: Where Are We Now?

Study Design: Narrative review. Objective: There is a strong biological rationale to perform early decompression after traumatic spinal cord injury (SCI). With an enlarging clinical evidence base, most spine surgeons internationally now favor early decompression for the majority of SCI patients; however, a number of pertinent questions remain surrounding this therapy. Methods: A narrative review evaluating the status of early surgery for SCI. In particular, we addressed the following questions: (1) Which patients stand to benefit most from early surgery? 2) What is the most appropriate time threshold defining early surgery? Results: Although heterogeneity exists, the evidence generally seems to support early surgery. While the best evidence exists for cervical SCI, there is insufficient data to support a differential effect for early surgery depending on neurological level or injury severity. When comparing thresholds to define early versus late surgery-including a later threshold (48-72 hours), an earlier threshold (24 hours), and an ultra-early threshold (8-12 hours)-the 2 earlier time points seem to be associated with the greatest potential for improved outcomes. However, existing prehospital and hospital logistics pose barriers to early surgery in a significant proportion of patients. An overview of recommendations from the recent AOSpine guidelines is provided. Conclusion: In spite of increasing acceptance of early surgery post SCI, further research is needed to (1) identify subgroups of patients who stand to derive particular benefit-in particular to develop more evidence-based approaches for central cord syndrome and (2) investigate the efficacy and feasibility of ultra-early surgery targeting more aggressive timelines

Perfect refiners for permutation group backtracking algorithms

We therefore thank the VolkswagenStiftung (Grant no. 93764 ) and the Royal Society (Grant code URF\R\180015) again for their financial support of this earlier work. For financial support during the more recent advances, we thank the DFG (Grant no. WA 3089/9-1) and again the Royal Society (Grant codes RGF\EA\181005 and URF\R\180015 ).Backtrack search is a fundamental technique for computing with finite permutation groups, which has been formulated in terms of points, ordered partitions, and graphs. We provide a framework for discussing the most common forms of backtrack search in a generic way. We introduce the concept of perfect refiners to better understand and compare the pruning power available in these different settings. We also present a new formulation of backtrack search, which allows the use of graphs with additional vertices, and which is implemented in the software package VOLE. For each setting, we classify the groups and cosets for which there exist perfect refiners. Moreover, we describe perfect refiners for many naturally-occurring examples of stabilisers and transporter sets, including applications to normaliser and subgroup conjugacy problems for 2-closed groups.Publisher PDFPeer reviewe

Computing canonical images in permutation groups with Graph Backtracking

We describe a new algorithm for finding a canonical image of an object under the action of a finite permutation group. This algorithm builds on previous work using Graph Backtracking, which extends Jeffrey Leon's Partition Backtrack framework. Our methods generalise both Nauty and Steve Linton's Minimal image algorithm.Comment: This is a revised version as re-submitte

Permutation group algorithms based on directed graphs

Funding: The authors would like to thank the DFG (Grant no. WA 3089/6-1) and the VolkswagenStiftung (Grant no. 93764) for financially supporting this work and projects leading up to it. The first and third authors are supported by the Royal Society (Grant codes RGF\EA\181005 and URF\R\180015).We introduce a new framework for solving an important class of computational problems involving finite permutation groups, which includes calculating set stabilisers, intersections of subgroups, and isomorphisms of combinatorial structures. Our techniques are inspired by and generalise 'partition backtrack', which is the current state-of-the-art algorithm introduced by Jeffrey Leon in 1991. But, instead of ordered partitions, we use labelled directed graphs to organise our backtrack search algorithms, which allows for a richer representation of many problems while often resulting in smaller search spaces. In this article we present the theory underpinning our framework, we describe our algorithms, and we show the results of some experiments. An implementation of our algorithms is available as free software in the Graph Back tracking package for GAP.Publisher PDFPeer reviewe

Análisis de la generación piezoeléctrica mediante el estudio de las fluctuaciones de presión hidráulica

Realizar un análisis técnico para la generación de energía eléctrica a través de los dispositivos piezoeléctricos mediante las fluctuaciones en la presión hidráulica, producida en los reservorios de almacenamiento y distribución de agua en una zona del cantón Pedro Moncayo.El aumento de la población y la industria a nivel mundial ha generado un crecimiento en la demanda energética, por lo tanto; la búsqueda y desarrollo de nuevas fuentes de captación de energía se ha convertido en un pilar fundamental para satisfacer las necesidades de la sociedad, adicionalmente es necesario que aquellas nuevas fuentes sean amigables con el medio ambiente y aprovechen todas las formas de producción posible. La generación piezoeléctrica se ha considerado como una alternativa eficiente para la generación de energía eléctrica, debido al aprovechamiento de la energía mecánica producida en el medio ambiente y por diversas actividades humanas para la producción de electricidad. Los procesos que generan energía cinética pueden ser convertidos en electricidad utilizando generadores piezoeléctricos, como pueden ser el aprovechamiento de las oscilaciones hidráulicas tanto de sistemas de tuberías como de depósitos naturales. En la presente investigación se desarrolla cuatro modelos piezoeléctricos de generación colocados en un sistema cerrado de tuberías de distribución de agua potable, donde el promedio de circulación del líquido es de 29 l/s, alcanzando un nivel de voltaje promedio por generador de 12.77 V en el primer, 11.90 V en el segundo, 9.16 V en el tercero y 14.28 V en el cuarto generador. A partir del análisis matemático y el desarrollo de los diferentes prototipos se realiza una proyección para el estudio de factibilidad de generación piezoeléctrica a partir de fluctuaciones hidráulicas, el sistema de generación trata de satisfacer pequeñas cargas de consumo de tal manera que la energía producida a partir del generador piezoeléctrico pueda ser aprovechada.Ingenierí