Regional geochemical and geophysical surveys in the Berwyn Dome and adjacent areas, north Wales

This report describes stream sediment and gravity surveys carried out across the Berwyn Dome and adjacent areas. The gravity survey confirmed the presence of a broad regional Bouguer anomaly low in the central part of the Dome, on which is superimposed several smaller irregular highs and lows. Some of these local anomalies possibly reflect small igneous bodies but more detailed gravity surveys would be needed to determine their form. Near Corwen the Bryneglwys Fault coincides with a 4.5 mGa1 anomaly but southwards the two features diverge, suggesting that the density interface is related either to a splay fault or to the eastern margin of the Lower Palaeozoic Montgomery trough. Some other structural trends are weakly reflected on the Bouguer anomaly and aeromagnetic maps, but there is no clear correlation with known base metal mineralisation. The Bouguer anomalies cannot be attributed to particular structures with any certainty but are probably due to a number of factors, including variation in the Precambrian basement and changes in the lithology and thickness of Lower Palaeozoic sedimentary rocks. There is no evidence for a large granitic body in Lower Palaeozoic rocks underlying the mineralisation at Llangynog. The aeromagnetic map suggests the presence of a magnetic basement at a depth of 3-4 km centred beneath the northwestern margin of the Dome. The stream sediment survey involved the collection of a - 100 mesh stream sediment, panned concentrate and water sample from each of the 399 sites sampled. The sample density was 1 site per 1.5 km*. Cu, Pb, Zn, Ba, Fe, Mn, Co, V, Cr, Ni, Zr, MO and Sn were determined in the stream sediments, Cu, Pb, Zn, Ba, Fe, Mn, Ce, Sn, Sb, Ti, Ni and As in the panned concentrates and Cu, Pb and Zn in stream waters. Major variations in the results are related to (i) hydrous oxide precipitation processes, (ii) contamination from human activities, (iii) base metal and baryte mineralisation, (iv) monazite concentrations in panned concentrates, (v) hitherto unrecorded gold mineralisation and (vi) lithological variations. The latter were related principally to shale-sandstone variation, but groups of elements attributable to the presence of basic intrusions, phosphatic rocks, coal measures, sandstones, limestones and volcanics were also discerned. Threshold levels were established from cumulative frequency curve analysis, and some anomalous sites were examined in the field. Anomalies did not form prominent coherent groups and were generally weak and scattered, with a wide variety of element groupings reflecting a range of causes. Many anomalous panned concentrates were examined mineralogically to try to . determine whether anomalies were related to chemically extreme background lithologies, contamination, or mineralisation. All the anomalies were related to one or more of the major causes of variation, although because of the very limited amount of follow-up work carried out the precise cause of many anomalies remains uncertain. No anomaly is considered to represent a strong prospect but several deserve further limited investigation, notably those associated with (i) gold mineralisation in the northwest of the area, (ii) baryte, perhaps accompanied by base metal ’ mineralisation, associated with Caradocian volcanics and phosphatic rocks at several localities, (iii) mineralisation associated with Llandeilian limestones and volcanic rocks north of Llanrhaeadr, and (iv) copper mineralisation associated with intrusives near the eastern margin of the Dome, where survey data is most incomplete

The non-coplanar baselines effect in radio interferometry: The W-Projection algorithm

We consider a troublesome form of non-isoplanatism in synthesis radio telescopes: non-coplanar baselines. We present a novel interpretation of the non-coplanar baselines effect as being due to differential Fresnel diffraction in the neighborhood of the array antennas. We have developed a new algorithm to deal with this effect. Our new algorithm, which we call "W-projection", has markedly superior performance compared to existing algorithms. At roughly equivalent levels of accuracy, W-projection can be up to an order of magnitude faster than the corresponding facet-based algorithms. Furthermore, the precision of result is not tightly coupled to computing time. W-projection has important consequences for the design and operation of the new generation of radio telescopes operating at centimeter and longer wavelengths.Comment: Accepted for publication in "IEEE Journal of Selected Topics in Signal Processing

Implementing Bring Your Own Device and the Paperless Classroom: A Change Leadership Project

My journey through the implementation of an action plan for a Bring Your Own Device (BYOD) program is presented in this research document. The action plan incorporated the addition of industrial certification standards for technology integrated into the core curriculum at a public middle school (grades 6-8) during the 2014-2015 school year. Technology skills became a part of students’ daily learning opportunities. An eSTEAM Academy provided interested students and teachers with technology training and skills for classroom inclusion and blended model of face-to-face instruction enhanced with technology in a “paperless” classroom environment. This is an account of our successful journey in the ever changing, ever challenging pursuit of technology infused 21st Century educational excellence

Optimal Image Reconstruction in Radio Interferometry

We introduce a method for analyzing radio interferometry data which produces maps which are optimal in the Bayesian sense of maximum posterior probability density, given certain prior assumptions. It is similar to maximum entropy techniques, but with an exact accounting of the multiplicity instead of the usual approximation involving Stirling's formula. It also incorporates an Occam factor, automatically limiting the effective amount of detail in the map to that justified by the data. We use Gibbs sampling to determine, to any desired degree of accuracy, the multi-dimensional posterior density distribution. From this we can construct a mean posterior map and other measures of the posterior density, including confidence limits on any well-defined function of the posterior map.Comment: 41 pages, 11 figures. High resolution figures 8 and 9 available at http://www.astro.uiuc.edu/~bwandelt/SuttonWandelt200

Evaluation of matrix-assisted laser desorption ionisation time-of-flight mass spectrometry (MALDI-TOF MS) for the Identification of Group B Streptococcus.

Objective Group B Streptococcus (GBS) is a leading cause of neonatal meningitis and sepsis worldwide. Intrapartum antibiotics given to women carrying GBS are an effective means of reducing disease in the first week of life. Rapid and reliable tests are needed to accurately identify GBS from these women for timely intrapartum antibiotic administration to prevent neonatal disease. Many laboratories now use matrix-assisted laser desorption ionisation time-of-flight mass spectrometry (MALDI-TOF MS) by direct plating or cell lysis for the identification of GBS isolates. The cell lysis step increases time to results for clinical samples and is more complex to perform. Therefore, we seek to evaluate the sensitivity and specificity of the quicker and more rapid direct plating method in identifying GBS. Results We directly compared swab isolates analysed by both direct plating and cell lysis method and demonstrated that direct plating has a sensitivity and specificity of 0.97 and 1, respectively, compared to an additional cell lysis step. We demonstrated that MALDI-TOF MS can be successfully used for batch processing by the direct plating method which saves time. These results are reassuring for laboratories worldwide who seek to identify GBS from swabs samples as quickly as possible

Self-Templated Nucleation in Peptide and Protein aggregation

Peptides and proteins exhibit a common tendency to assemble into highly ordered fibrillar aggregates, whose formation proceeds in a nucleation-dependent manner that is often preceded by the formation of disordered oligomeric assemblies. This process has received much attention because disordered oligomeric aggregates have been associated with neurodegenerative disorders such as Alzheimer's and Parkinson's diseases. Here we describe a self-templated nucleation mechanism that determines the transition between the initial condensation of polypeptide chains into disordered assemblies and their reordering into fibrillar structures. The results that we present show that at the molecular level this transition is due to the ability of polypeptide chains to reorder within oligomers into fibrillar assemblies whose surfaces act as templates that stabilise the disordered assemblies.Comment: 4 pages, 3 figure

Leaf Traits Within Communities: Context May Affect the Mapping of Traits to Function

The leaf economics spectrum (LES) has revolutionized the way many ecologists think about quantifying plant ecological trade-offs. In particular, the LES has connected a clear functional trade-off (long-lived leaves with slow carbon capture vs. short-lived leaves with fast carbon capture) to a handful of easily measured leaf traits. Building on this work, community ecologists are now able to quickly assess species carbon-capture strategies, which may have implications for community-level patterns such as competition or succession. However, there are a number of steps in this logic that require careful examination, and a potential danger arises when interpreting leaf-trait variation among species within communities where trait relationships are weak. Using data from 22 diverse communities, we show that relationships among three common functional traits (photosynthetic rate, leaf nitrogen concentration per mass, leaf mass per area) are weak in communities with low variation in leaf life span (LLS), especially communities dominated by herbaceous or deciduous woody species. However, globally there are few LLS data sets for communities dominated by herbaceous or deciduous species, and more data are needed to confirm this pattern. The context-dependent nature of trait relationships at the community level suggests that leaf-trait variation within communities, especially those dominated by herbaceous and deciduous woody species, should be interpreted with caution