Manipulation and the causal Markov condition

This paper explores the relationship between a manipulability conception of causation and the causal Markov condition (CM). We argue that violations of CM also violate widely shared expectations—implicit in the manipulability conception—having to do with the absence of spontaneous correlations. They also violate expectations concerning the connection between independence or dependence relationships in the presence and absence of interventions

British fair play: sport across diasporas at the BBC World Service

This chapter uses archive material to explore the role of sports broadcasting on the BBC World Service in the twentieth century.Whereas the service's early audiences were expatriate British listeners, the BBC WS recruited different diasporic audiences later into the twentieth century.This chapter looks at specific sports and at the accommodations of the tensions between the WS's links with both Empire and with discourses of impartiaility, which have led to both endurances in the postcolonialist aspects of sport as well as new opportunities for reconfigurations of diaspora

An evaluation of some alternative approaches for reducing fan tone noise

The potential of two alternative approaches for reducing fan ton noise was investigated in this study. One of these approaches increases the number of rotor blades to shift the tone noise to higher frequencies that are not rated as strongly by the perceived noise scale. This alternative fan also would have a small number of long chord stator vanes which would reduce the stator response and lower rotor-stator interaction noise. Comparison of the conventional and alternative fan concepts showed that this alternative approach has as large or larger a perceived tone noise reduction potential as the conventional approach. The other alternative, a high Mach number inlet, is evaluated both for its noise attenuation and for its change in noise directivity

Downward Causation and Levels

This chapter discusses a number of different notions of level, including levels as involving compositional relations and levels as relatively explanatorily autonomous. The notion of downward causation, understood as causation from upper to lower levels, is defended as legitimate. Downward causation is elucidated in terms of a relation called conditional causal independence: X is causally independent of Y conditional on Z when X is causally relevant (in the standard interventionist sense) to Z, Y is causally relevant to Z but conditional on the values of Z, changes in the value of X make no further difference to Y. When Y is a lower-level realizer of X and conditional independence holds, we can use Y rather than X to explain Z and the Y to Z relation is conditionally autonomous from X-level facts

Flagpoles Anyone? Causal and Explanatory Asymmetries

This paper discusses some procedures developed in recent work in machine learning for inferring causal direction from observational data. The role of independence and invariance assumptions is emphasized. Several familiar examples including Hempel’s flagpole problem are explored in the light of these ideas. The framework is then applied to problems having to do with explanatory direction in non-causal explanation

Laws: An Invariance- Based Account

This paper defends an invariance-based account of laws of nature: Laws are generalizations that remain invariant (stable, robust) under various sorts of changes. Alternatively, laws are generalizations that exhibit a certain kind of independence from background conditions

American Obesity: Rooted in Uncertainty, Institutions and Public Policy

Despite the efforts of policymakers, medical professionals, and other stakeholders, obesity and related health problems show no signs of receding from their record-high rates. Public policy has largely taken the form of consumer advice, (e.g., USDA’s Dietary Guidelines). Since consumers bear most of the costs associated with their obesity, the goal of obesity prevention appears to be incentive-compatible, prima facie. That is, there is no a priori case for much further policy intervention unless existing advice is deficient or consumers’ exhibit systematically poor decision-making. My review of the literature shows that scholars have long conveyed a consistent narrative regarding our scientific understanding of obesity—one which emphasizes the apparent behavioral ‘anomalies’ of consumers. Unacknowledged by most investigators is a body of scientific literature which, if valid, severely undermines the predictive and explanatory power of most accepted models of obesity. That is, credible institutions may prevent consumers from discovering obesity-alleviating diets because nutrition authorities and policymakers have condoned only one approach to healthy eating for several decades. I advance a theory of obesity rooted in Shacklean uncertainty about the operationally relevant characteristics upon which consumers should base their decisions. I relax the standard assumption that consumers exhibit open satiation isocalorically. To measure consumer preferences in the pre-obesity epidemic era, I perform a content analysis of American cookbooks from the early 18th to the middle of the 20th century. Results show that, if anything, past Americans preferred food that would be considered worse—even further from the USDA ideal. Using USDA survey data (1994-1996), I construct a finite mixture model to analyze Americans’ consumption patterns, preferences, knowledge, and beliefs about diet and health. My estimation shows that Americans were aware of the tenets of healthy eating at that time and consumption patterns were broadly consistent with the strength of these beliefs and preferences. I argue that economic theory would not predict rates of obesity doubling in the interim, given consumers’ continued exposure to information and their experiences. I hypothesize that this is evidence for a significant discrepancy between institutionalized advice and advice which is truly effective— a form of uncertainty. I use the extant scientific literature to show the ways in which healthy decision-making is constrained relative to what it would be under counterfactual policy arrangements. I do not reject the null hypothesis that consumers would have been at least as well off with no policy at all. I use the same dataset to replicate Butler’s (1982) work which models the relationship between social stigma and the decision-making of consumers who receive food stamps

Nutrition Policy, Nonmarket Failure, and the Obesity Epidemic

The Dietary Guidelines for Americans, which are based on the Dietary Goals for the United States, represent the federal government’s first attempt to improve the nation’s health by recommending that Americans avoid certain foods. The Guidelines were based on what was perceived, by the government and nutritionists alike, to be solid scientific evidence that consumption of fat and saturated fat in particular, increase the risk of developing heart disease. They also emphasized, and continue to emphasize, the importance of exercise and calorie restriction as the primary means of maintaining a healthy weight. In short, the Guidelines sought to correct the market failure of information asymmetry so that Americans could make better food consumption decisions in relation to their health. My review of the literature indicates that neither hypothesis had any solid scientific evidence to support it at the time. An alternative hypothesis, of which the federal government was aware, posited that refined carbohydrates were the driving force behind increasing rates of heart disease and obesity at the time the Goals were published. But, by that time, most of the scientific and medical community was convinced of the supposed dangers of consuming fat, and endorsed the Guidelines which advise Americans to consume mostly carbohydrates and limit intake of fat and saturated fat, among other messages. Though, at the time, these recommendations faced some controversy because of the lack of concrete evidence for either hypothesis it has all but disappeared in the interim even though no compelling scientific evidence has surfaced to support them. I employ a framework based on a volume published by the Brookings Institution to evaluate whether the Goals and Guidelines should have been pursued as well as Charles Wolf, Jr.’s paper on non-market failure to understand potential reasons for their persistence in their current form. Based on the scientific evidence available at the time, I conclude that there was little justification for publishing the Guidelines, according to the Brookings text. A growing body of evidence supports the alternative hypothesis of what leads to obesity, which is sometimes referred to as the insulin hypothesis. There appear to be considerable internalities that may impede the implementation of new recommendations based on the insulin hypothesis, according to Wolf’s framework. To be clear, no robust evidence exists to completely refute either view of this growing public health problem. Using data from the United Nations for 36 countries, I end the paper with a regression analysis, using a fixed-effects model, which attempts to determine whether consumption of refined carbohydrates contributes to increased consumption of total calories. I find that it does and at a statistically significant level. Though I find this evidence somewhat compelling, more rigorous and controlled studies are necessary to better determine the precise relationship between diet and health outcomes. Only then can the Guidelines be considered a credible policy document

The optimisation of nitrogen content for micropropagation of eucalyptus marginata

The use of eucalypts for plantation timber and pulp is becoming increasingly important, as are eucalypts that are resistant to disease and insect herbivory. Where clones with desirable traits have been selected, it is important that these genotypes are preserved. Micropropagation of some eucalypts, and Eucalyptus marginata in particular, can be difficult possibly due to the currently used basal medium of Murashige and Skoog (M&S)(I 962). By examining the nitrogen utilisation and the effects of medium pH of this species, it may be possible to improve general micropropagation protocol. Six clones of the species E. marginata were obtained as shoot cultures. The pH of M&S medium was successfully buffered using 2-(Nmorpholino) ethanesulfonic acid (MES) for both shoot multiplication and root induction. This did not result in any growth increase. Increased growth was achieved when shoots were grown on buffered medium that contained less nitrogen than M&S (20 mM and 40 mM) and the nitrogen was supplied solely as nitrate. Shoots grown on buffered (I 0 mM MES) root induction medium produced more roots than those grown on unbuffered medium. Root induction medium containing nitrate as the sole source produced more roots than did media with ammonium and nitrates or solely ammonium. These results suggest that E. marginata prefers nitrate to ammonium as a nitrogen source, and that the current level of total nitrogen may be too high. The pH of culture medium for both shoot multiplication and root induction remained constant with nitrate as the sole nitrogen source but fell significantly when ammonium was the sole source. This occurred even when MES was supplied at I 0 mM. Increasing the level of MES to 20 mM in the medium resulted in less shoot growth. When different clones were subjected to the same treatments, significant differences in shoot growth and percentage of rooting between clones were observed, highlighting the genetic variability within the species