Applying the Extended Mathews stability graph to stress relaxation, site specific effects and narrow vein stoping

The original Mathews method for predicting stope stability has been extended and now contains 483 open stoping and caving case histories over a wide range of geotechnical conditions and stope dimensions. The mathematical framework upon which the Extended Mathews stability graph is based and the large database has facilitated examination of a number of outstanding issues surrounding the application of empirical stability graphs. This paper summarises how the framework of the Extended Mathews stability graph framework has been applied to quantify the effect of stress relaxation upon excavation stability, examine site-specifi c effects and highlight the poor correlation between stability graph parameters for narrow stope stability. Back-analysis of case studies where stope surfaces were relaxed has enabled the effect of stress relaxation upon excavation stability to be quantified and bounded. Detailed statistical analyses have demonstrated that a reliable stable-failure boundary requires at least 150 case histories, of which a minimum of 10% should be unstable stope surfaces. Marginal site-specifi c effects were observed for the operating conditions captured within the database. Apparent site-specifi c effects noted in previous literature were found to be attributable to operating conditions inadequately represented in the database. Statistical analysis of overbreak from 115 narrow-vein case studies has demonstrated that operating conditions in narrow-vein mines differ suffi ciently to warrant changes in the model framework to account for undercutting of stope walls and drill and blast parameters. Backfi ll abutments were found to behave the same as solid rock abutments

forall x: Calgary. An Introduction to Formal Logic

forall x: Calgary is a full-featured textbook on formal logic. It covers key notions of logic such as consequence and validity of arguments, the syntax of truth-functional propositional logic TFL and truth-table semantics, the syntax of first-order (predicate) logic FOL with identity (first-order interpretations), translating (formalizing) English in TFL and FOL, and Fitch-style natural deduction proof systems for both TFL and FOL. It also deals with some advanced topics such as truth-functional completeness and modal logic. Exercises with solutions are available. It is provided in PDF (for screen reading, printing, and a special version for dyslexics) and in LaTeX source code

A fictionalist theory of universals

Universals are putative objects like wisdom, morality, redness, etc. Although we believe in properties (which, we argue, are not a kind of object), we do not believe in universals. However, a number of ordinary, natural language constructions seem to commit us to their existence. In this paper, we provide a fictionalist theory of universals, which allows us to speak as if universals existed, whilst denying that any really do

Hard thermal loops effective action for piO -> gamma gamma

I consider the low temperature correction to the anomalous coupling of a neutral pion to two photons from an effective Lagrangian point of view.Comment: 4 pages, revtex. Talk given by M. Tytgat at the 5th International Workshop on Thermal Field Theories and their Applications, Regensburg (Germany), August 199

Against Cumulative Type Theory

Standard Type Theory, ${\textrm {STT}}$, tells us that $b^n$ is well-formed iff $n=m+1$. However, Linnebo and Rayo [23] have advocated the use of Cumulative Type Theory, $\textrm {CTT}$, which has more relaxed type-restrictions: according to $\textrm {CTT}$, $b^\beta$ is well-formed iff $\beta\u3e\alpha$. In this paper, we set ourselves against $\textrm {CTT}$. We begin our case by arguing against Linnebo and Rayo’s claim that $\textrm {CTT}$ sheds new philosophical light on set theory. We then argue that, while $\textrm {CTT}$ ’s type-restrictions are unjustifiable, the type-restrictions imposed by ${\textrm {STT}}$ are justified by a Fregean semantics. What is more, this Fregean semantics provides us with a principled way to resist Linnebo and Rayo’s Semantic Argument for $\textrm {CTT}$. We end by examining an alternative approach to cumulative types due to Florio and Jones [10]; we argue that their theory is best seen as a misleadingly formulated version of ${\textrm {STT}}$

Substitution in a sense

The Reference Principle (RP) states that co-referring expressions are everywhere intersubstitutable salva congruitate. On first glance, (RP) looks like a truism, but a truism with some bite: (RP) transforms difficult philosophical questions about co-reference into easy grammatical questions about substitutability. This has led a number of philosophers to think that we can use (RP) to make short work of certain longstanding metaphysical debates. For example, it has been suggested that all we need to do to show that the predicate ‘( ) is a horse’ does not refer to a property is point out that ‘( ) is a horse’ and ‘the property of being a horse’ are not everywhere intersubstitutable salva congruitate. However, when we understand ‘substitution’ in the simplest and most straightforward way, (RP) is no truism; in fact, natural languages are full of counterexamples to the principle. In this paper, I introduce a new notion of substitution, and then develop and argue for a version of (RP) that is immune to these counterexamples. Along the way I touch on the following topics: the relation between argument forms and their natural language instances; the reification of sense; the difference between terms and predicates; and the relation between reference and disquotation. I end by arguing that my new version of (RP) cannot be used to settle metaphysical debates quite as easily as some philosophers would like

Characteristics of patients expressing an interest in ketamine treatment:results of an online survey

Background: Off-label ketamine treatment has shown acute antidepressant effects that offer hope for patients with therapy-resistant depression. However, its potential for integration into treatment algorithms is controversial, not least because the evidence base for maintenance treatment with repeated ketamine administration is currently weak. Ketamine is also a drug of misuse, which has raised concerns regarding the target population. Little is known about which patients would seek ketamine treatment if it were more widely available. Aims: To explore some of the characteristics of the patients actively seeking ketamine treatment. Method: An online survey containing questions about duration of current depressive episode, number of antidepressants used and other comments was completed by patients who were exploring the internet regarding the possibility of ketamine for depression. Results: Of the 1088 people who registered their interest, 93.3% reported depression, 64.3% reported a chronic course of their symptoms and in the past 10 years, 86.3% had tried at least two antidepressants. Desperation was a common theme, but this appeared to be competently expressed. A small minority (<8%) reported experience of illegal ketamine use. Conclusions: It cannot be ruled out that patients with different degrees of treatment resistance and comorbidities will seek treatment with ketamine. This stresses the urgency to perform larger randomised controlled trials as well as to systematically monitor outcomes and adverse effects of ketamine, that is currently prescribed off-label for patients in need. Declaration of interest: R.M. is consulting and is Principal Investigator for Janssen trials of esketamine and is consulting for Eleusis

Improving the biological interfacing capability of Improving the biological interfacing capability of diketopyrrolopyrrole polymers via p-type doping

Polydiketopyrrolopyrrole terthiophene (DPP3T), a high-performing conjugated polymer, holds great potential as active material for bioelectronics. Herein, its surface properties are modulated through p-type doping, thereby enhancing the cell behaviour on top of the doped films

Assessing depleted uranium (DU) contamination of soil, plants and earthworms at UK weapons testing sites

Depleted uranium (DU) weapons testing programmes have been conducted at two locations within the UK. An investigation was therefore carried out to assess the extent of any environmental contamination arising from these test programmes using both alpha spectrometry and mass spectrometry techniques. Uranium isotopic signatures indicative of DU contamination were observed in soil, plant and earthworm samples collected in the immediate vicinity of test firing points and targets, but contamination was found to be localised to these areas. The paper demonstrates the superiority of the 235U:238U ratio over the 234U:238U ratio for identifying and quantifying DU contamination in environmental samples and also describes the respective circumstances under which alpha spectrometry or mass spectrometry may be the more appropriate analytical tool

The Prenective View of Propositional Content

Beliefs have what I will call ‘propositional content’. A belief is always a belief that so-and-so: a belief that grass is green, or a belief that snow is white, or whatever. Other things have propositional content too, such as sentences, judgments and assertions. The Standard View amongst philosophers is that what it is to have a propositional content is to stand in an appropriate relation to a proposition. Moreover, on this view, propositions are objects, i.e. the kind of thing you can refer to with singular terms. For example, on the Standard View, we should parse the sentence ‘Simon believes that Sharon is funny’ as: [Simon] believes [that Sharon is funny]; ‘Simon’ is a term referring to a thinking subject, ‘that Sharon is funny’ is a term referring to a proposition, and ‘x believes y’ is a dyadic predicate expressing the believing relation. In this paper, I argue against the Standard View. This is how I think we should parse ‘Simon believes that Sharon is funny’: [Simon] believes that [Sharon is funny]; here we have a singular term, ‘Simon’, a sentence ‘Sharon is funny’, and a ‘prenective’ joining them together, ‘x believes that p’. On this Prenective View, we do not get at the propositional content of someone’s belief by referring to a reified proposition with a singular term; we simply use the sentence ‘Sharon is funny’ to express that content for ourselves. I argue for the Prenective View in large part by showing that an initially attractive version of the Standard View is actually vulnerable to the same objection that Wittgenstein used against Russell’s multiple-relation theory of judgment