In the United States, approximately 2.53 million people sustain a concussion each year. Relative to adults, youth show greater cognitive deficits following concussion and a longer recovery. An accurate and reliable imaging method is needed to determine injury severity and symptom resolution. The primary objective of this study was to characterize concussions with diffusion tensor imaging. This was performed through a normative Z-scoring analysis of DTI metrics, fractional anisotropy, axial diffusivity, and radial diffusivity, to quantify patient-specific injuries and identify commonly (...) damaged brain regions in paediatric concussion patients relative to healthy controls. It was hypothesized that personalizing the detection analysis through normative Z-scoring would provide an understanding of trauma-induced microstructural damage. Concussion patients were volunteers recruited from the Emergency Department of the McMaster Children’s Hospital with a recent concussion, 9 males and 17 females, mean age 14.22 ± 2.64, while healthy paediatric brain DTI datasets were obtained from an MRI data repository. Significant abnormalities were commonly found in the longitudinal fasciculus, fronto-occipital fasciculus, and corticospinal tract, while unique abnormalities were localized in a number of other areas reflecting the individuality of each child’s injury. Total injury burden, determined by the number of regions containing outliers per DTI metric per patient, was used as the metric to quantify the overall injury severity of each patient. The primary outcome of this analysis found that younger patients experienced a significantly greater injury burden when measured using fractional anisotropy. These results show that DTI was able to detect microstructural changes caused by concussion, on a per-person basis, and has the potential to be a useful tool for improving diagnostic accuracy and prognosis of a concussion. (shrink)

From one of the most influential scientists of our time, a dazzling exploration of the hidden laws that govern the life cycle of everything from plants and animals to the cities we live in. The former head of the Sante Fe Institute, visionary physicist Geoffrey West is a pioneer in the field of complexity science, the science of emergent systems and networks. The term "complexity" can be misleading, however, because what makes West's discoveries so beautiful is that he has (...) found an underlying simplicity that unites the seemingly complex and diverse phenomena of living systems, including our bodies, our cities and our businesses. Fascinated by issues of aging and mortality, West applied the rigor of a physicist to the biological question of why we live as long as we do and no longer. The result was astonishing, and changed science, creating a new understanding of energy use and metabolism: West found that despite the riotous diversity in the sizes of mammals, they are all, to a large degree, scaled versions of each other. If you know the size of a mammal, you can use scaling laws to learn everything from how much food it eats per day, what its heart-rate is, how long it will take to mature, its lifespan, and so on. Furthermore, the efficiency of the mammal's circulatory systems scales up precisely based on weight: if you compare a mouse, a human and an elephant on a logarithmic graph, you find with every doubling of average weight, a species gets 25% more efficient--and lives 25% longer. This speaks to everything from how long we can expect to live to how many hours of sleep we need. Fundamentally, he has proven, the issue has to do with the fractal geometry of the networks that supply energy and remove waste from the organism's body. (shrink)

In this essay, I first extend the insights of virtue ethics into environmental ethics and examine the possible dangers of this approach. Second, I analyze some qualities of character that an environmentally virtuous person must possess. Third, I evaluate “humility” as an environmental virtue, specifically, the position of Thomas E. Hill, Jr. I conclude that Hill’s conception of “proper” humility can be more adequatelyexplicated by associating it with another virtue, environmental “openness.”.

In this essay, I first extend the insights of virtue ethics into environmental ethics and examine the possible dangers of this approach. Second, I analyze some qualities of character that an environmentally virtuous person must possess. Third, I evaluate “humility” as an environmental virtue, specifically, the position of Thomas E. Hill, Jr. I conclude that Hill’s conception of “proper” humility can be more adequatelyexplicated by associating it with another virtue, environmental “openness.”.

It is often said in physics that if two models of a theory are related by a symmetry, then the two models provide (or could provide) two different representations of the very same situation, alike the case of two maps of different color for the very same city. It is also said that the situations represented by two models of a theory are indiscernible in some ways when the models in question are related by a symmetry of the theory, just (...) like the situation in the interior of the cabin of a train when the train is at rest in the station is empirically indiscernible from the situation in the interior when the train is moving uniformly (in classical mechanics, these two situations are represented by two models related by a boost). In recent years, philosophers of physics have focused a lot of attention in developing various principles that aim to elucidate these and similar remarks on symmetries, models, physical equivalence, and representation that are widespread in physics practice. The goal of the current article is to provide a critical review of these principles, and suggest a new framework for thinking about these kinds of questions. One important upshot of the paper is that questions of indiscernibility, and questions of the representational capacity of models, must be distinguished from one another. (shrink)

1. Is consciousness vague? This paper will argue that it is. But, first, we need to get clear on the meaning of the question.I will take vagueness to consist in the possibility of borderline cases....

The principle of sufficient reason threatens modal collapse. Some have suggested that by appealing to the indefinite extensibility of contingent truth, the threat is neutralized. This paper argues that this is not so. If the indefinite extensibility of contingent truth is developed in an analogous fashion to the most promising models of the indefinite extensibility of the concept set, plausible principles permit the derivation of modal collapse.

Traditional theories of associative learning have found no place for the possibility that the way in which events are perceived might change as a result of experience. Evidence for the reality of perceptual learning has come from those studied by learning theorists. The work reviewed in this book shows that learned changes in perceptual organization can in fact be demonstrated, even in experiments using procedures of the type on which associative theories have been based. These results come from procedures that (...) have been the focus of detailed theoretical and empirical analysis; and from this analysis emerges an outline of the mechanisms responsible. Some of these are themselves associative; others require the addition of nonassociative mechanisms to the traditional theory. The result is an extended version of associative theory which, it is argued, will be relevant not only to the experimental procedures discussed in this book but to the entire range of instances of perceptual learning. (shrink)

There has been increased interest in developing what I call environmental virtue ethics (EVE). This paper presents some of the centralfeatures of this project. The first part is a general description of EVE, showing why there is a need for it. The second part spells out the central features of EVE including an account of the good life as flourishing in an expanded or mixed biotic community, and provides a tentative list of important environmental virtues. The third part examines one (...) virtue: friendship, showing how an understanding of it provides insight into current issues in environmental ethics. The final section addresses a challenge to the project of EVE. (shrink)

Recently some philosophers have defended the thesis that naturalness, or joint-carvingness, is an aim of belief. This paper argues that there is an important class of counterexamples to this thesis. In particular, it is argued that naturalness is not an aim of our beliefs concerning what is joint carving and what is not.

What is the connection between having a phenomenal property and knowing that one has that property? A traditional view on the matter takes the connection to be quite intimate. Whenever one has a phenomenal property, one knows that one does. Recently most authors have denied this traditional view. The goal of this paper is to defend the traditional view. In fact, I will defend something much stronger: I will argue that what it is for a property to be phenomenal is (...) for it to be a property one must know oneself to have when on has it. As we will see, this theory has a number of surprising and welcome upshots, suggesting that the traditional view has been unjustly maligned. (shrink)

It is often said in physics that if two models of a theory are related by a symmetry, then the two models provide (or could provide) two different representations of the very same situation, alike the case of two maps of different color for the very same city. It is also said that the situations represented by two models of a theory are indiscernible in some ways when the models in question are related by a symmetry of the theory, just (...) like the situation in the interior of the cabin of a train when the train is at rest in the station is empirically indiscernible from the situation in the interior when the train is moving uniformly (in classical mechanics, these two situations are represented by two models related by a boost). In recent years, philosophers of physics have focused a lot of attention in developing various principles that aim to elucidate these and similar remarks on symmetries, models, physical equivalence, and representation that are widespread in physics practice. The goal of the current article is to provide a critical review of these principles, and suggest a new framework for thinking about these kinds of questions. One important upshot of the paper is that questions of indiscernibility, and questions of the representational capacity of models, must be distinguished from one another. (shrink)

Propositions represent the entities from which they are formed. This fact has puzzled philosophers and some have put forward radical proposals in order to explain it. This paper develops a primitivist account of the representational properties of propositions that centers on the operation of application. As we will see, this theory wins out over its competitors on grounds of strength, systematicity and unifying power.

A heuristic proof is given that the divergent QCD perturbation series is, asymptotic. By treating it as an asymptotic expansion we show that it makes sense to keep only the first few terms. The example of e+e− annihilation is considered. It is shown that by keeping only the first few terms one can get within a per cent (or smaller) of the complete sum of the series even at very low momenta where the coupling is large. More generally, this affords (...) an explanation of the phenomena of precocious scaling and why keeping only leading order corrections generally works so well. (shrink)

Studies of conditioning in simple systems are best interpreted in terms of the formation of excitatory links. The mechanisms responsible for such conditioning contribute to the associative learning effects shown by more complex systems. If a dual-system approach is to be avoided, the best hope lies in developing standard associative theory to deal with phenomena said to show propositional learning.

It is known that, on average, people adapt their choice of memory strategy to the subjective utility of interaction. What is not known is whether an individual's choices are boundedly optimal. Two experiments are reported that test the hypothesis that an individual's decisions about the distribution of remembering between internal and external resources are boundedly optimal where optimality is defined relative to experience, cognitive constraints, and reward. The theory makes predictions that are tested against data, not fitted to it. The (...) experiments use a no-choice/choice utility learning paradigm where the no-choice phase is used to elicit a profile of each participant's performance across the strategy space and the choice phase is used to test predicted choices within this space. They show that the majority of individuals select strategies that are boundedly optimal. Further, individual differences in what people choose to do are successfully predicted by the analysis. Two issues are discussed: the performance of the minority of participants who did not find boundedly optimal adaptations, and the possibility that individuals anticipate what, with practice, will become a bounded optimal strategy, rather than what is boundedly optimal during training. (shrink)

This passage is discussed in AJPb 97 , 252, by D. R. Shackleton Bailey, who rightly draws attention to the ‘absurdity’’ of exilii specie sepositos and observes that ‘Ausonius must be saying that the brothers were banished in fact, though not in name’’. Shackleton Bailey's solution is to replace exilii with bospitii, which gives excellent sense, but, even on the assumption of psychological error by a scribe, which is how Shackleton Bailey explains the corruption, may seem rather hard to credit. (...) An easier solution might be to write auxilii for exilii: in appearance Constantine's brothers were being helped and protected, in reality confined in exile. (shrink)

This passage is discussed in AJPb 97, 252, by D. R. Shackleton Bailey, who rightly draws attention to the ‘absurdity’’ of exilii specie sepositos and observes that ‘Ausonius must be saying that the brothers were banished in fact, though not in name’’. Shackleton Bailey's solution is to replace exilii with bospitii, which gives excellent sense, but, even on the assumption of psychological error by a scribe, which is how Shackleton Bailey explains the corruption, may seem rather hard to credit. An (...) easier solution might be to write auxilii for exilii: in appearance Constantine's brothers were being helped and protected, in reality confined in exile. (shrink)