A statistical approach for the integrated analysis of mine-induced seismicity and numerical stress estimates, a case study—Part I: developing the relations

Integrated analyses at a number of underground operations have suggested that qualitative relations may exist between microseismic variable values estimated in real-time from mine seismic systems and the stress estimates provided by numerical models. In this study, multivariate statistical techniques were used to evaluate whether quantitative relations could be formed using data from the Creighton Mine in Sudbury, Ontario. It is believed that if sufficiently reliable relations could be developed, they might then be exploited to better characterize the state of the rock mass and provide insight beyond what could be obtained from either data set in isolation. This insight could then be used to eventually impact both short- and long-term mine design decisions.This paper represents the second part of a two part series and describes the evaluation of the 11 statistically significant relations that were formed in the first paper between variables within the stress and seismic databases. Specifically, the model adequacy and the stability of each relation was evaluated. In addition, the prediction capabilities of each relation were evaluated and the relations were interpreted relative to prior experience and physical theory.The results of this component of the study indicated that all but three of the developed relations met the statistical requirements for relations of this type and all were shown to be quite stable. In terms of prediction, it was demonstrated that this could best be achieved through the application of Discriminant Function Analysis. This technique was shown to be capable of suggesting which events were generated under relatively high-stress conditions, though the technique was less successful at correctly identifying events generated under lower stress conditions. Interpretation focussed on the relation between the stress conditions at the source and two particular variables from the seismic database and concluded that the observed variations in source strength were primarily controlled by spatial variations in confinement. The importance of a rigorous methodology was also discussed, as was potential ways in which the relations of the types formed in this study could impact mine design decisions.     

Sterol biosynthesis inhibitors: Their current status and modes of action

The mechanism of each of the reactions in the post-squalene segment of the fungal and higher plant sterol biosynthetic pathway is outlined. The inhibitors of the enzymes catalyzing the reactions are described and how inhibition is brought about is explained in the areas where it is known. Based on a paper presented at the Symposium on Plant and Fungal Sterols: Biosynthesis, Metabolism and Function, held at the AOCS Annual Meeting, Baltimore, MD, April 1990.     

Compared properties of aromatic polyisophthalamides containing 5‐(4‐acetoxy‐benzamido) pendent groups

A series of aromatic polyamides containing 5‐(4‐acetoxy‐benzamido) pendent groups have been synthesized and their properties have been characterized and compared with those of related polyamides. The polyamides have weight‐ and number‐average molecular weights in the range of 36,680–65,700 and 12,685–35,490, respectively, and polydispersities in the range of 1.82–3.66. These polymers show good thermal stability comparable to traditional aromatic polyisophthalamides, with initial decomposition temperature between 270–320°C and glass transition temperature in the range of 230–270°C. Compared with related polyisophthalamides without any pendent groups, the present polymers show better solubility in certain solvents such as N‐methylpyrrolidinone and dimethylacetamide and can be cast from solutions into thin transparent flexible films having dielectric constants in the range of 3.42–4.27. The polymer films display remarkable hydrophilicity, which makes them potential candidates for use as advanced materials in humidity sensors. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 650–657, 2001     

An Autonomous Unmanned Ground Vehicle for Non-Destructive Testing of Fiber-Reinforced Polymer Bridge Decks

The use of fiber-reinforced polymer (FRP) composite bridge decks is increasing in many civil engineering applications because of its many useful properties. The traditional reinforced concrete bridge decks have steel reinforcing bars embedded in concrete. Because of the use of deicing salt on the bridges to melt snow and ice in winter, the reinforcing bars tend to corrode, thus reducing the life span of the reinforced concrete bridge decks by half (from about 50 yr to about 25 yr). The FRP composite decks are made of noncorrosive material and offer a higher strength-to-weight ratio as compared to the reinforced concrete decks. It is highly important that engineers know how to detect subsurface defects that can form in FRP decks, which may cause serious structural degradation and endanger structural integrity. Both infrared thermography (IRT) and ground penetrating radar (GPR) have shown promise in the field of non-destructive detection of defects. Instead of performing both analysis methods individually, it would be more cost effective for someone to conduct both IRT and GPR at the same time. Research at West Virginia University has produced an unmanned ground vehicle (UGV) that will acquire data from both GPR and IRT systems to create a combined defect map of the FRP bridge deck to better analyze the results. Thus, the proposed UGV enables rapid data acquisition from the FRP bridge deck in an automated and non-destructive fashion, which minimizes human error. The UGV also incorporates data analysis algorithms, which help in producing a detailed map showing the layout of defects on the bridge deck.     

Cooperative Vaccinia Infection Demonstrated at the Single-Cell Level Using FluidFM

The mechanisms used by viruses to enter and replicate within host cells are subjects of intense investigation. These studies are ultimately aimed at development of new drugs that interfere with these processes. Virus entry and infection are generally monitored by dispensing bulk virus suspensions on layers of cells without accounting for the fate of each virion. Here, we take advantage of the recently developed FluidFM to deposit single vaccinia virions onto individual cells in a controlled manner. While the majority of virions were blocked prior to early gene expression, infection of individual cells increased in a nondeterministic fashion with respect to the number of viruses placed. Microscopic analyses of several stages of the virus lifecycle indicated that this was the result of cooperativity between virions during early stages of infection. These findings highlight the importance of performing controlled virus infection experiments at the single cell level.     

An investigation of the micromechanisms of fatigue crack growth in structural gas turbine engine alloys

This paper presents an overview of fatigue fracture modes in selected structural alloys employed in gas turbine engines. These include the mechanisms of fatigue crack growth in the near-threshold, Paris and high-K regimes obtained from Ti-6Al-4V, Inconel 718 and PWA 1472 (a single crystal nickel-based superalloy of similar chemical composition to Inconel 718). Fatigue fracture modes in these materials are shown to be strong functions of the stress intensity factor range, K, and the maximum stress intensity factor, K _max. Fatigue mechanism maps are also presented to show the parametric ranges of K and K _max corresponding to the different fatigue fracture modes.     

Not all negative words slow down lexical decision and naming speed: Importance of word arousal.

Previously the authors (see record 2006-04603-006) analyzed sets of words used in emotion Stroop experiments and found little evidence of automatic vigilance, for example, slower lexical decision time (LDT) or naming speed for negative words after controlling for lexical features. If there is a slowdown evoked by word negativity, most studies to date overestimate the effect because word negativity is often confounded with lexical features that promote slower word recognition. Estes and Adelman (this issue; see record 2008-09984-001) analyze a new set of words, controlling for important lexical features, and find a small but significant effect for word negativity. Moreover, they conclude the effect is categorical. The authors analyze the same data set but include the arousal value of each word. The authors find nonlinear and interaction effects in predicting LDT and naming speed. Not all negative words produce the generic slowdown. Paradoxically, negative words that are moderate to low on arousal produce more LDT slowing than negative words higher on arousal. This finding presents a theoretical and empirical challenge to researchers wishing to understand the boundaries of the automatic vigilance effect. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Acid phosphatase isoenzymes in Gaucher's disease

Acid phosphatase (EC 3.1.3.2) isoenzyme profiles of extracts of splenic tissue and serum from patients with Gaucher's disease were measured by a mini-column ion-exchange chromatographic method [Clin. Chem., 23, 000 (1977)]. Diagnosis of Gaucher's disease in the five patients studied was confirmed by demonstrating decreased (2.3 to 4.1% of normal) glucocerebrosidase activity in the spleen. With p-nitrophenyl phosphate as substrate, increased acid phosphatase activity (three-to eight-fold normal) was demonstrated in spleen tissue from Gaucher;s disease patients; isoenzyme profiles by the ion-exchange column technique showed acid phosphatase isoenzyme 5 to be the predominant isoenzyme. Comparison of acid phosphatase isoenzyme profiles from patients with Gaucher's disease and prostatic carcinoma revealed distinct differences in the activities of isoenzymes 2 and 5. The isoenzyme-5 measurement thus appears to provide a diagnostic test for Gaucher's disease that can be done reapidly and easily in the routine clinical chemistry laboratory.     

The crystallisation of glasses based on the eutectic compositions in the system Li2O-Al2O3-SiO2

A study has been made of the crystallisation of glasses based on the eutectic between lithium metasilicate and-eucryptite and of the rÔle of TiO₂ in promoting fine-grained crystallisation. The hypothesis advanced in part 1 of this work is extended to a semi-quantitative measure of the effect of TiO₂.Characteristics of two metastable phases are described in an appendix.