The natural history of bugs: using formal methods to analyse software related failures in space missions

Space missions force engineers to make complex trade-offs between many different constraints including cost, mass, power, functionality and reliability. These constraints create a continual need to innovate. Many advances rely upon software, for instance to control and monitor the next generation ‘electron cyclotron resonance’ ion-drives for deep space missions.Programmers face numerous challenges. It is extremely difficult to conduct valid ground-based tests for the code used in space missions. Abstract models and simulations of satellites can be misleading. These issues are compounded by the use of ‘band-aid’ software to fix design mistakes and compromises in other aspects of space systems engineering. Programmers must often re-code missions in flight. This introduces considerable risks. It should, therefore, not be a surprise that so many space missions fail to achieve their objectives. The costs of failure are considerable. Small launch vehicles, such as the U.S. Pegasus system, cost around $18 million. Payloads range from$4 million up to $1 billion for security related satellites. These costs do not include consequent business losses. In 2005, Intelsat wrote off$73 million from the failure of a single uninsured satellite. It is clearly important that we learn as much as possible from those failures that do occur. The following pages examine the roles that formal methods might play in the analysis of software failures in space missions

A Critique of Wolak’s Evaluation of the NZ Electricity Market: Introduction and Overview

This paper is the first in a symposium of papers that examine the 2009 report by Frank Wolak into the New Zealand electricity market. The Wolak report concluded that there had been a cumulative total of $4.3b (NZD) of overcharging in the New Zealand wholesale market over a period of seven years. In this paper, we introduce the Wolak findings in the context of the salient features of the New Zealand market, and explain that this headline figure is highly sensitive to some (quite unrealistic) assumptions about the structure of this market. The papers that follow this introduction (Hogan and Jackson, 2011, and Evans and Guthrie, 2011) examine Wolak’s methodology and its empirical application.Wolak Report; electricity markets; market power

Arizona’s Rising STEM Occupational Demands and Declining Participation in the Scientific Workforce: An Examination of Attitudes among African Americans toward STEM College Majors and Careers

According to the Bureau of Labor Statistics (2008), science, technology, engineering, and math (STEM) occupations constitute a growing sector of Arizona’s economy. However, the number of African Americans earning degrees related to these occupations has not kept pace with this growth. Increasing the participation of African Americans in STEM education fields and subsequent related occupations in Arizona is vital to growing and maintaining the state’s economic stature. This objective is made even more compelling given that each year, from 2008– 2018, there are 3,671 projected job openings in STEM fields in Arizona. This study explores the extent to which the attitudes held by African Americans in Arizona toward STEM related majors and careers influence their likelihood of joining the state’s scientific workforce. Our analyses reveal the importance of career consideration, confidence in one’s ability to be successful in a STEM related field, and family support of the pursuit of STEM education and careers.Educatio

Strange quarks in quenched twisted mass lattice QCD

Two twisted doublets, one containing the up and down quarks and the other containing the strange quark with an SU(2)-flavor partner, are used for studies in the meson sector. The relevant chiral perturbation theory is presented, and quenched QCD simulations (where the partner of the strange quark is not active) are performed. Pseudoscalar meson masses and decay constants are computed; the vector and scalar mesons are also discussed. A comparison is made to the case of an untwisted strange quark, and some effects due to quenching, discretization, and the definition of maximal twist are explored.Comment: 37 pages, 12 figures, accepted for publicatio

Integration of HIV Care with Primary Health Care Services: Effect on Patient Satisfaction and Stigma in Rural Kenya.

HIV departments within Kenyan health facilities are usually better staffed and equipped than departments offering non-HIV services. Integration of HIV services into primary care may address this issue of skewed resource allocation. Between 2008 and 2010, we piloted a system of integrating HIV services into primary care in rural Kenya. Before integration, we conducted a survey among returning adults ≥18-year old attending the HIV clinic. We then integrated HIV and primary care services. Three and twelve months after integration, we administered the same questionnaires to a sample of returning adults attending the integrated clinic. Changes in patient responses were assessed using truncated linear regression and logistic regression. At 12 months after integration, respondents were more likely to be satisfied with reception services (adjusted odds ratio, aOR 2.71, 95% CI 1.32-5.56), HIV education (aOR 3.28, 95% CI 1.92-6.83), and wait time (aOR 1.97 95% CI 1.03-3.76). Men's comfort with receiving care at an integrated clinic did not change (aOR = 0.46 95% CI 0.06-3.86). Women were more likely to express discomfort after integration (aOR 3.37 95% CI 1.33-8.52). Integration of HIV services into primary care services was associated with significant increases in patient satisfaction in certain domains, with no negative effect on satisfaction

Pathways to research impact in primary healthcare: What do Australian primary healthcare researchers believe works best to facilitate the use of their research findings?

This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.Background Primary healthcare researchers are under increasing pressure to demonstrate measurable and lasting improvement in clinical practice and healthcare policy as a result of their work. It is therefore important to understand the effectiveness of the research dissemination strategies used. The aim of this paper is to describe the pathways for research impact that have been achieved across several government-funded primary healthcare projects, and the effectiveness of these methods as perceived by their Chief Investigators. Methods The project used an online survey to collect information about government-funded primary healthcare research projects. Chief Investigators were asked how they disseminated their findings and how this achieved impact in policy and practice. They were also asked to express their beliefs regarding the most effective means of achieving research impact and describe how this occurred. Results Chief Investigators of 17 projects indicated that a number of dissemination strategies were used but that professional networks were the most effective means of promoting uptake of their research findings. Utilisation of research findings for clinical practice was most likely to occur in organisations or among individual practitioners who were most closely associated with the research team, or when research findings were included in educational programmes involving clinical practice. Uptake of both policy- and practice-related research was deemed most successful if intermediary organisations such as formal professional networks were engaged in the research. Successful primary healthcare researchers had developed critical relationships with intermediary organisations within primary healthcare before the initiation of the research and had also involved them in the design. The scale of research impact was influenced by the current policy environment, the type and significance of the results, and the endorsement (or lack thereof) of professional bodies. Conclusions Chief Investigators believed that networks were the most effective means of research dissemination. Researchers who were embedded in professional, clinical or policy-focussed intermediary organisations, or had developed partnerships with clinical services, which had a vested interest in the research findings, were more able to describe a direct impact of their research. This suggests that development of these relationships and engagement of these stakeholders by primary healthcare researchers is a vital step for optimal research utilisation in the primary healthcare setting

Mary's Powers of Imagination

One common response to the knowledge argument is the ability hypothesis. Proponents of the ability hypothesis accept that Mary learns what seeing red is like when she exits her black-and-white room, but they deny that the kind of knowledge she gains is propositional in nature. Rather, she acquires a cluster of abilities that she previously lacked, in particular, the abilities to recognize, remember, and imagine the color red. For proponents of the ability hypothesis, knowing what an experience is like simply consists in the possession of these abilities. Criticisms of the ability hypothesis tend to focus on this last claim. Such critics tend to accept that Mary gains these abilities when she leaves the room, but they deny that such abilities constitute knowledge of what an experience is like. To my mind, however, this critical strategy grants too much. Focusing specifically on imaginative ability, I argue that Mary does not gain this ability when she leaves the room for she already had the ability to imagine red while she was inside it. Moreover, despite what some have thought, the ability hypothesis cannot be easily rescued by recasting it in terms of a more restrictive imaginative ability. My purpose here is not to take sides in the debate about physicalism, i.e., my criticism of the ability hypothesis is not offered in an attempt to defend the anti-physicalist conclusion of the knowledge argument. Rather, my purpose is to redeem the imagination from the misleading picture of it that discussion of the knowledge argument has fostered

Social work as a career choice (a study of selected variables in the choice of social work as a career)

Thesis (M.S.)--Boston Universit

Grounding, Analysis, and Russellian Monism

Few these days dispute that the knowledge argument demonstrates an epistemic gap between the physical facts and the facts about experience. It is much more contentious whether that epistemic gap can be used to demonstrate a metaphysical gap of a kind that is inconsistent with physicalism. In this paper I will explore two attempts to block the inference from an epistemic gap to a metaphysical gap – the first from the phenomenal concept strategy, the second from Russellian monism – and suggest how the proponent of the knowledge argument might respond to each of these challenges. In doing so, I will draw on recent discussions of grounding and essence in the metaphysics literature

The price of inscrutability

In our reasoning we depend on the stability of language, the fact that its signs do not arbitrarily change in meaning from moment to moment.(Campbell, 1994, p.82) Some philosophers offer arguments contending that ordinary names such as “London” are radically indeterminate in reference. The conclusion of such arguments is that there is no fact of the matter whether “London” refers to a city in the south of England, or whether instead it refers to Sydney, Australia. Some philosophers have even suggested that we accept the conclusion of these arguments. Such a position seems crazy to many; but what exactly goes wrong if one adopts such a view? This paper evaluates the theoretical costs incurred by one who endorses extreme inscrutability of reference (the ‘inscrutabilist’). I show that there is one particular implication of extreme inscrutability which pushes the price of inscrutabilism too high. An extension of the classic ‘permutation’ arguments for extreme inscrutability allow us to establish what I dub ‘extreme indexical inscrutability’. This result, I argue, unacceptably undermines the epistemology of inference. The first half of the paper develops the background of permutation arguments for extreme inscrutability of reference and evaluates some initial attempts to make trouble for the inscrutabilist. Sections 1 and 2 describe the setting of the original permutation arguments for extreme inscrutability. Sections 3 and 4 survey four potential objections to extreme inscrutability of reference, including some recently raised in Vann McGee’s excellent (2005a). Sections 5 sketches how the permutation arguments can be generalized to establish extreme indexical inscrutability; and shows how this contradicts a ‘stability principle’—that our words do not arbitrarily change their reference from one moment to the next—which I claim plays a vital role in the epistemology of inference. The second half of the paper develops in detail the case for thinking that language is stable in the relevant sense. In section 6, I use this distinction to call into question the epistemological relevance of validity of argument types; Kaplan’s treatment of indexical validity partially resolves this worry, but there is a residual problem. In section 7, I argue that stability is exactly what is needed to bridge this final gap, and so secure the relevance of validity to good inferential practice. Section 8 responds to objections to this claim. An appendix to the paper provides formal backing for the results cited in this paper, including a generalization of permutation arguments to the kind of rich setting required for a realistic semantics of natural language.1 Extreme indexical inscrutability results can be proved within this setting. The first half of the paper shows that the inscrutabilist is committed to extreme indexical inscrutability, which implies that language not determinately ‘stable’. The second half of the paper argues that good inference requires stability. The price of inscrutabilism, therefore, is to sever the connection between the validity of argument-forms and inferential practice: and this is too high a price to pay