Chances, counterfactuals and similarity

John Hawthorne in a recent paper takes issue with Lewisian accounts of counterfactuals, when relevant laws of nature are chancy. I respond to his arguments on behalf of the Lewisian, and conclude that while some can be rebutted, the case against the original Lewisian account is strong. I develop a neo-Lewisian account of what makes for closeness of worlds. I argue that my revised version avoids Hawthorne’s challenges. I argue that this is closer to the spirit of Lewis’s first (non-chancy) proposal than is Lewis’s own suggested modification

The influence of laser hardening on wear in the valve and valve seat contact

In internal combustion engines it is important to manage the wear in the valve and valve seat contact in order to minimise emissions and maximise economy. Traditionally wear in this contact has been controlled by the use of a valve seat insert and the careful selection of materials for both the valve and the insert. More recently, due to the increasing demands for both performance and cost, alternative methods of controlling the wear, and the resulting valve recession, have been sought. Using the heating effect of a laser to induce localised phase transformations, to increase hardness and wear resistance, in materials has been used since the 1970s, however it is only in recent years that it has been able to compete with more established surface treatment techniques, particularly in terms of cost, as new laser hardware has been developed. In this work, a laser has been used to treat the valve seat area of a cast iron cylinder head. In order to optimise the laser parameters for use on the head, preliminary tests were carried out to investigate the fundamental wear characteristics of untreated cast iron and also cast iron with a range of laser treatments. Previous work has identified the predominant wear mechanism in the valve and valve seat contact as impact on valve closure. Two bespoke test machines, one for testing basic specimens and one for testing components, were used to identify the laser parameters most likely to yield acceptable results when applied to a cylinder head to be used in a fired dynamometer test. © 2009 Elsevier B.V. All rights reserved

What's metaphysical about metaphysical necessity?

I begin by contrasting three approaches one can take to the distinction between the essential and accidental properties: an ontological, a deflationary, and a mind-dependent approach. I then go on to apply that distinction to the necessary a posteriori, and defend the deflationist view. Finally I apply the distinction to modal truth in general and argue that the deflationist position lets us avoid an otherwise pressing problem for the actualist: the problem of accounting for the source of modal truth

Web Single Sign-On Authentication using SAML

Companies have increasingly turned to application service providers (ASPs) or Software as a Service (SaaS) vendors to offer specialized web-based services that will cut costs and provide specific and focused applications to users. The complexity of designing, installing, configuring, deploying, and supporting the system with internal resources can be eliminated with this type of methodology, providing great benefit to organizations. However, these models can present an authentication problem for corporations with a large number of external service providers. This paper describes the implementation of Security Assertion Markup Language (SAML) and its capabilities to provide secure single sign-on (SSO) solutions for externally hosted applications

A history of Beverly, Massachusetts (for use in junior high schools).

Thesis (Ed.M.)--Boston Universit

Wheel/Rail Contact Isolation Due to Track Contamination

An experimental study has been carried out to investigate the effect of sanding on the electrical isolation of a wheel/rail contact. Sand is applied to the wheel/rail interface to increase adhesion in both braking and traction. Train detection, for signalling purposes, can be by means of track circuits. Signalling block occupancy is triggered by the wheelset of the train ‘shorting out’ the track circuit. Sand in the wheel/rail interface means that contact between the wheelsets and the track may be compromised, inhibiting train identification. Static tests were performed using sections cut from wheels and rail and dynamic tests on a twin disc machine where rail and wheel steel discs are loaded together and driven under controlled conditions of rolling and slip. The electrical circuit used was a simplified simulation of the TI21 track circuit. The application of sand was carried out under a range of mild and severe test conditions. The results indicated that a transition exists in the amount of sand applied, below which there is a measurable, but not severe, change in voltage, but above which the contact conductance decreases by an order of magnitude. A model of electrical isolation has been developed assuming either full disc separation by a sand layer or partial disc contact with some sand present. Idealisations inherent in both test methods mean that they represent a severe case. Given these limitations, it is likely that the test methods, at their present stage of development, should be used as a means to qualitatively assess the relative effects on electrical isolation of different contaminants

All properly ergodic Markov chains over a free group are orbit equivalent

Previous work showed that all Bernoulli shifts over a free group are orbit-equivalent. This result is strengthened here by replacing Bernoulli shifts with the wider class of properly ergodic countable state Markov chains over a free group. A list of related open problems is provided.Comment: Comments and questions welcome

Efficient sampling of fast and slow cosmological parameters

Physical parameters are often constrained from the data likelihoods using sampling methods. Changing some parameters can be much more computationally expensive (`slow') than changing other parameters (`fast parameters'). I describe a method for decorrelating fast and slow parameters so that parameter sampling in the full space becomes almost as efficient as sampling in the slow subspace when the covariance is well known and the distributions are simple. This gives a large reduction in computational cost when there are many fast parameters. The method can also be combined with a fast 'dragging' method proposed by Neal (2005) that can be more robust and efficient when parameters cannot be fully decorrelated a priori or have more complicated dependencies. I illustrate these methods for the case of cosmological parameter estimation using data likelihoods from the Planck satellite observations with dozens of fast nuisance parameters, and demonstrate a speed up by a factor of five or more. In more complicated cases, especially where the fast subspace is very fast but complex or highly correlated, the fast-slow sampling methods can in principle give arbitrarily large performance gains. The new samplers are implemented in the latest version of the publicly available CosmoMC code.Comment: 11 pages, 4 figures; minor clarifications, additional references and brief disussion of alternative method

Placing Children with Relatives: The Case for a Clear Rationale for Separate Foster Care Licensing Standards, Background Check Procedures, and Improved Relative Placement Statutes in Alaska

Policymakers generally agree that if a child cannot live safely with her parents, then the child should be placed expeditiously with a relative. Alaska’s current system for evaluating relative caregivers is overly complicated, creating unnecessary barriers for relatives and increasing the risk of mistakenly denying placement with relatives. This Article argues that Alaska should adopt a three-step approach to achieve better outcomes based on the American Bar Association’s model licensing standards, which are narrowly tailored to evaluate whether a child should be placed with a relative. Additionally, this Article argues that Alaska should repeal its state statute that gives the child welfare agency the ability to establish prima facie evidence to deny a relative if a relative would not be eligible for a foster care license, for two reasons. First, a review of the history of the state’s statutes indicates that the legislature did not intend to provide the Department of Health and Human Services with the current definition of prima facie evidence. Second, Alaska’s current statute is not compliant with the 2016 federal regulations regarding the Indian Child Welfare Act. Lastly, this Article argues that Alaska should adopt a statute clearly delineating the court’s authority to order placement of a child facing foster care with a relative to expedite compliance with relative placement in frontline child welfare practice. Adopting these proposals would reduce barriers and the number of mistakes in frontline child welfare practice, which would increase both the timeliness and the number of children placed with relatives

Animating hatreds: research encounters, organisational secrets, emotional truths

About the book: Feminist research is informed by a history of breaking silences, of demanding that women's voices be heard, recorded and included in wider intellectual genealogies and histories. This has led to an emphasis on voice and speaking out in the research endeavour. Moments of secrecy and silence are less often addressed. This gives rise to a number of questions. What are the silences, secrets, omissions and and political consequences of such moments? What particular dilemmas and constraints do they represent or entail? What are their implications for research praxis? Are such moments always indicative of voicelessness or powerlessness? Or may they also constitute a productive moment in the research encounter? Contributors to this volume were invited to reflect on these questions. The resulting chapters are a fascinating collection of insights into the research process, making an important contribution to theoretical and empirical debates about epistemology, subjectivity and identity in research. Researchers often face difficult dilemmas about who to represent and how, what to omit and what to include. This book explores such questions in an important and timely collection of essays from international scholars