Fifth annual conference on Alaskan placer mining

An abridged format of papers, presentations and addresses given during the 1983 conference held on March 30-31, 1983 compiled and edited by Bruce W. Campbell, Jim Madonna, and M. Susan Husted.Partial funding was provided by the Carl G. Parker Memorial Publishing Fund, University of Alaska, Fairbanks, and the Mining and Mineral Resources Research Institute, U.S. Department of the Interior, Bureau of Mines

Providing decision support for the condition-based maintenance of circuit breakers through data mining of trip coil current signatures

The focus of this paper centers on the condition assessment of 11kV-33kV distribution circuit breakers from the analysis of their trip coil current signatures captured using an innovative condition monitoring technology developed by others. Using available expert knowledge in conjunction with a structured process of data mining, thresholds associated with features representing each stage of a circuit breaker's operation may be defined and used to characterize varying states of circuit breaker condition. Knowledge and understanding of satisfactory and unsatisfactory breaker condition can be gained and made explicit from the analysis of captured trip signature data and subsequently used to form the basis of condition assessment and diagnostic rules implemented in a decision support system, used to inform condition-based decisions affecting circuit breaker maintenance. This paper proposes a data mining method for the analysis of condition monitoring data, and demonstrates this method in its discovery of useful knowledge from trip coil data captured from a population of SP Power System's in-service circuit breakers. This knowledge then forms the basis of a decision support system for the condition assessment of these circuit breakers during routine trip testing

Factors contributing to the time taken to consult with symptoms of lung cancer: a cross-sectional study

<b>Objectives</b>: To determine what factors are associated with the time people take to consult with symptoms of lung cancer, with a focus on those from rural and socially deprived areas. <b>Methods</b>: A cross-sectional quantitative interview survey was performed of 360 patients with newly diagnosed primary lung cancer in three Scottish hospitals (two in Glasgow, one in NE Scotland). Supplementary data were obtained from medical case notes. The main outcome measures were the number of days from (1) the date participant defined first symptom until date of presentation to a medical practitioner; and (2) the date of earliest symptom from a symptom checklist (derived from clinical guidelines) until date of presentation to a medical practitioner. <b>Results</b>: 179 participants (50%) had symptoms for more than 14 weeks before presenting to a medical practitioner (median 99 days; interquartile range 31–381). 270 participants (75%) had unrecognised symptoms of lung cancer. There were no significant differences in time taken to consult with symptoms of lung cancer between rural and/or deprived participants compared with urban and/or affluent participants. Factors independently associated with increased time before consulting about symptoms were living alone, a history of chronic obstructive pulmonary disease (COPD) and longer pack years of smoking. Haemoptysis, new onset of shortness of breath, cough and loss of appetite were significantly associated with earlier consulting, as were a history of chest infection and renal failure. <b>Conclusion</b>: For many people with lung cancer, regardless of location and socioeconomic status, the time between symptom onset and consultation was long enough to plausibly affect prognosis. Long-term smokers, those with COPD and/or those living alone are at particular risk of taking longer to consult with symptoms of lung cancer and practitioners should be alert to this

Defining and investigating difficult asthma: Developing quality indicators

SummaryBackgroundThere is no agreed definition of ‘difficult asthma’ or what investigations should be available to investigate these patients. Patients with difficult asthma remain symptomatic on high levels of treatment and are high users of medical resources.AimTo develop a set of quality indicators for the definition and investigation of difficult asthma.MethodModified RAND Appropriateness Method was used. An expert panel composed of nine hospital asthma specialists who run ‘difficult’ asthma clinics and were identified from a shortlist of key workers in the field. Indicators were rated as necessary to define and investigate difficult asthma.ResultsDifficult asthma was defined as ‘symptoms persisting beyond therapy consistent with step 4 of the British Thoracic Society (BTS) guidelines’ (high dose inhaled corticosteroids and long acting β2-agonists). Eighty-three indicators were identified (40 relating to definition and 43 relating to investigations). Of these 32 (39%) were rated as necessary: 7 out of 40 (18%) for defining difficult asthma and 23 out of 43 (53%) for investigations. Indicators of high medical resource usage were characteristic of the ‘difficult’ nature of the management of patient with difficult asthma. A framework for the investigation of these patients was created.ConclusionThe listed performance indicators identify a range of requirements that are necessary to define difficult asthma. Targeting of real needs in this group of patients will lead to better patient care and reduction of ‘waste’ in provision of healthcare

Experimental and Finite Element Analysis of the Open-Cells Porous Materials Subjected to Compression Mechanical Loading

Progress in Additive Manufacturing (AM) technology enables the fabrication of complex structures that could not be obtained with traditional manufacturing methods. One AM research area is the development and use of lightweight products with cellular structures, containing complex lattices and pores, which give improved performance and functionality. It is well known that there is a strong link between mechanical properties and architecture of samples with cellular structures. This paper presents a comparison and validation of Finite Element Analysis (FEA) simulations of cellular structures with experimental data obtained from compression tests, and degradation behaviour under load compression. The specimens, with spherical open-cells, were produced in VeroClear RGD810 photopolymer resin. Mechanical compression tests were performed to investigate the compressive behaviour and the mechanical response was registered in the form of compressive stress-strain curves. Also, using the specimens’ CAD data and compression test parameters, a Finite Element Analysis (FEA) was performed. A macroscopic analysis of the specimens’ structure and microhardness tests before and after compression tests were also carried out

Exploring the role of crystal habit in the Ostwald rule of stages

The crystallization of calcium carbonate is shown to be dictated by the Ostwald rule of stages (ORS), for high relative initial supersaturations (SCaCO3=[Ca2+][CO2−3]/KSP, Calcite>2500), under sweet (carbon dioxide saturated) and anoxic (oxygen depleted) solution conditions. Rhombohedral calcite crystals emerge after the sequential crystallization and dissolution of the metastable polymorphs: vaterite (snowflake-shaped) and aragonite (needle-shaped). However, the presence of certain cations, which can form trigonal carbonates (e.g. Fe2+ and Ni2+), in concentrations as low as 1.5 mM, triggers the emergence of calcite crystals, with a star-shaped crystal habit, first. These star-shaped crystals dissolve to yield needle-shaped aragonite crystals, which in turn dissolve to give the rhombohedral calcite crystals. The star-shaped crystals, formed at high SCaCO3, possess higher surface free energy (therefore higher apparent solubility) than their rhombohedral counterparts. This sequence of dissolution and recrystallization demonstrates that the ORS does not only drive the crystal towards its thermodynamically most stable polymorph but also towards its most stable crystal habit

Absence of Phase Stiffness in the Quantum Rotor Phase Glass

We analyze here the consequence of local rotational-symmetry breaking in the quantum spin (or phase) glass state of the quantum random rotor model. By coupling the spin glass order parameter directly to a vector potential, we are able to compute whether the system is resilient (that is, possesses a phase stiffness) to a uniform rotation in the presence of random anisotropy. We show explicitly that the O(2) vector spin glass has no electromagnetic response indicative of a superconductor at mean-field and beyond, suggesting the absence of phase stiffness. This result confirms our earlier finding (PRL, {\bf 89}, 27001 (2002)) that the phase glass is metallic, due to the main contribution to the conductivity arising from fluctuations of the superconducting order parameter. In addition, our finding that the spin stiffness vanishes in the quantum rotor glass is consistent with the absence of a transverse stiffness in the Heisenberg spin glass found by Feigelman and Tsvelik (Sov. Phys. JETP, {\bf 50}, 1222 (1979).Comment: 8 pages, revised version with added references on the vanishing of the stiffness constant in the Heisenberg spin glas