Combining Weights of Evidence Analysis with Feature Extraction - A Case Study from the Hauraki Goldfield, New Zealand

© 2016 The Authors. In this contribution we combine different image processing and pattern recognition methodologies to map the probability of discovering epithermal mineral deposits in the northern part of the Coromandel peninsula, in New Zealand. The objective of this work is to propose a case-study where the substitution of structural geology GIS themes (commonly developed by humans) with products derived by image processing, computer-based, semi-automatic edge detection analyses, is carried out to reduce subjective input in the prospectivity analysis. Semi-automated lineament extraction results introduced in the mineral favourability statistical modelling can more easily reveal unexpected potentially mineralised target domains, being less subjective. We present initial results of this analysis and explain some of the methodologies adopted. Preliminary results suggest that this approach increases significantly the number of geological discontinuities mapped in the region, with the following implications: (1) prospectivity models are more risk-tolerant and result in an increased number of targets; (2) increments in posterior probability affect the statistical validity of the model due to conditional independence violation, requiring careful assessment of probability overestimation; (3) the feature extraction process identifies numerous lineaments that in some instances represent false positives (lineaments determined by a variety of causes, without geological significance); however, we find that Contrast calculations in the Bayesian analysis tend to penalize these evidential themes, because of the higher number of pixels (cells) containing a positive pattern (lineament existence = 1, being positive). This aspect reduces the overall impact of these predictors on the analysis, mitigating the effect of false positives (lower positive weights of evidence). Despite the limitations, results obtained are encouraging with a clearly superior and more detailed mapping of potential structural sites and their relative probabilities of hosting epithermal deposits

Combining weights of evidence analysis with feature extraction - a case study from the Hauraki Goldfield, New Zealand

In this contribution we combine different image processing and pattern recognition methodologies to map the probability of discovering epithermal mineral deposits in the northern part of the Coromandel peninsula, in New Zealand. The objective of this work is to propose a case-study where the substitution of structural geology GIS themes (commonly developed by humans) with products derived by image processing, computer-based, semi-automatic edge detection analyses, is carried out to reduce subjective input in the prospectivity analysis. Semi-automated lineament extraction results introduced in the mineral favourability statistical modelling can more easily reveal unexpected potentially mineralised target domains, being less subjective. We present initial results of this analysis and explain some of the methodologies adopted. Preliminary results suggest that this approach increases significantly the number of geological discontinuities mapped in the region, with the following implications: (1) prospectivity models are more risk-tolerant and result in an increased number of targets; (2) increments in posterior probability affect the statistical validity of the model due to conditional independence violation, requiring careful assessment of probability overestimation; (3) the feature extraction process identifies numerous lineaments that in some instances represent false positives (lineaments determined by a variety of causes, without geological significance); however, we find that Contrast calculations in the Bayesian analysis tend to penalize these evidential themes, because of the higher number of pixels (cells) containing a positive pattern (lineament existence = 1, being positive). This aspect reduces the overall impact of these predictors on the analysis, mitigating the effect of false positives (lower positive weights of evidence). Despite the limitations, results obtained are encouraging with a clearly superior and more detailed mapping of potential structural sites and their relative probabilities of hosting epithermal deposits

Structural insights into Clostridium perfringens delta toxin pore formation

Clostridium perfringens Delta toxin is one of the three hemolysin-like proteins produced by C. perfringens type C and possibly type B strains. One of the others, NetB, has been shown to be the major cause of Avian Nectrotic Enteritis, which following the reduction in use of antibiotics as growth promoters, has become an emerging disease of industrial poultry. Delta toxin itself is cytotoxic to the wide range of human and animal macrophages and platelets that present GM2 ganglioside on their membranes. It has sequence similarity with Staphylococcus aureus β-pore forming toxins and is expected to heptamerize and form pores in the lipid bilayer of host cell membranes. Nevertheless, its exact mode of action remains undetermined. Here we report the 2.4 Å crystal structure of monomeric Delta toxin. The superposition of this structure with the structure of the phospholipid-bound F component of S. aureus leucocidin (LukF) revealed that the glycerol molecules bound to Delta toxin and the phospholipids in LukF are accommodated in the same hydrophobic clefts, corresponding to where the toxin is expected to latch onto the membrane, though the binding sites show significant differences. From structure-based sequence alignment with the known structure of staphylococcal α-hemolysin, a model of the Delta toxin pore form has been built. Using electron microscopy, we have validated our model and characterized the Delta toxin pore on liposomes. These results highlight both similarities and differences in the mechanism of Delta toxin (and by extension NetB) cytotoxicity from that of the staphylococcal pore-forming toxins

3-(2-Chloro­ethyl)-2-methyl-4H-pyrido[1,2-a]pyrimidin-4-one

In the title mol­ecule, C11H11ClN2O, the pyrido[1,2-a]pyrimidine ring system is planar (maximum deviation = 0.0148 Å) and the methyl C and carbonyl O atoms are nearly coplanar to it. The chloro­ethyl side chain is in a synclinal conformation, nearly orthogonal to the pyrimidine ring, with a dihedral angle between the chloro­ethyl side chain and the pyrimidine ring of 88.5 (1)°. Weak inter­molecular C—H⋯N and C—H⋯Cl hydrogen bonds along with π–π inter­actions between the pyrimidine and pyridine rings [centroid–centroid distance is 3.538 (2) Å] form a three-dimensional network. The crystal is a racemic twin with a 0.68 (12):0.32 (12) domain ratio. MOPAC AM1 and density functional theory (DFT) theoretical calculations at the B3-LYP/6–311+G(d,p) level support these observations

Monitoring of activated sludge settling ability through image analysis : validation on full-scale wastewater treatment plants

In recent years, a great deal of attention has been focused on the research of activated sludge processes, where the solid–liquid separation phase is frequently considered of critical importance, due to the different problems that severely affect the compaction and the settling of the sludge. Bearing that in mind, in this work, image analysis routines were developed in Matlab environment, allowing the identification and characterization of microbial aggregates and protruding filaments in eight different wastewater treatment plants, for a combined period of 2 years. The monitoring of the activated sludge contents allowed for the detection of bulking events proving that the developed image analysis methodology is adequate for a continuous examination of the morphological changes in microbial aggregates and subsequent estimation of the sludge volume index. In fact, the obtained results proved that the developed image analysis methodology is a feasible method for the continuous monitoring of activated sludge systems and identification of disturbances.Empresa de Águas, Efluentes e Resíduos de Braga, Portugal - EM (AGERE)Fundação para a Ciência e a Tecnologia (FCT

Accreting Black Holes

This chapter provides a general overview of the theory and observations of black holes in the Universe and on their interpretation. We briefly review the black hole classes, accretion disk models, spectral state classification, the AGN classification, and the leading techniques for measuring black hole spins. We also introduce quasi-periodic oscillations, the shadow of black holes, and the observations and the theoretical models of jets.Comment: 41 pages, 18 figures. To appear in "Tutorial Guide to X-ray and Gamma-ray Astronomy: Data Reduction and Analysis" (Ed. C. Bambi, Springer Singapore, 2020). v3: fixed some typos and updated some parts. arXiv admin note: substantial text overlap with arXiv:1711.1025

Environmental regulation induced foreign direct investment

The last decade has witnessed a renewed interest in the relationship between environmental regulations and international capital flows. However, empirical studies have so far failed to find conclusive evidence for this so-called pollution haven or race to the bottom effect where foreign direct investment (FDI) is assumed to be attracted to low regulation countries, regions or states. In this paper we present a simple theoretical framework to demonstrate that greater stringency in environmental standards can lead to a strategic increase in capital inflows which we refer to as environmental regulation induced FDI. Our result reveals a possible explanation for the mixed results in the empirical literature and provides an illustration of the conditions under which environmental regulations in the host country can affect the location decision of foreign firms

Accreting Millisecond X-Ray Pulsars

Accreting Millisecond X-Ray Pulsars (AMXPs) are astrophysical laboratories without parallel in the study of extreme physics. In this chapter we review the past fifteen years of discoveries in the field. We summarize the observations of the fifteen known AMXPs, with a particular emphasis on the multi-wavelength observations that have been carried out since the discovery of the first AMXP in 1998. We review accretion torque theory, the pulse formation process, and how AMXP observations have changed our view on the interaction of plasma and magnetic fields in strong gravity. We also explain how the AMXPs have deepened our understanding of the thermonuclear burst process, in particular the phenomenon of burst oscillations. We conclude with a discussion of the open problems that remain to be addressed in the future.Comment: Review to appear in "Timing neutron stars: pulsations, oscillations and explosions", T. Belloni, M. Mendez, C.M. Zhang Eds., ASSL, Springer; [revision with literature updated, several typos removed, 1 new AMXP added

Dentists' use of validated child dental anxiety measures in clinical practice: a mixed methods study

Background: Assessing anxiety is an important part of the assessment of a child presenting for dental treatment; however, the use of dental anxiety scales in practice is not well-documented. Aims: To introduce child dental anxiety scales, and to monitor the extent to which dentists used them; to explore the experience and views of dentists regarding anxiety assessment. Design: A mixed-methods design was employed. Method: A protocol for child anxiety assessment was introduced to paediatric dentists in Eastman Dental Hospital. After 6 months, 100 patient files were audited to examine compliance with the protocol. Fourteen dentists were interviewed to explore their experience and views regarding anxiety assessment. Results: Only five patients were assessed using the scales. Thematic analysis of the dentist interviews revealed three themes: ‘Clinical observations and experience: The gold standard’; ‘Scales as an estimate or adjunct’; and ‘Shortcomings and barriers to using scales’. Conclusions: The dentists in our study did not use anxiety scales, instead they rely on their own experience/judgement. Therefore, scales should be recommended as an adjunct to judgement. Brief scales are recommended as clinicians lack time and expertise in administering anxiety questionnaires. Advantages of using scales and hands-on experience could be incorporated more in undergraduate training