In their simplest form, hybrid languages are propositional modal languages which can refer to states. They were introduced by Arthur Prior, the inventor of tense logic, and played an important role in his work: because they make reference to specific times possible, they remove the most serious obstacle to developing modal approaches to temporal representation and reasoning. However very little is known about the computational complexity of hybrid temporal logics.In this paper we analyze the complexity of the satisfiability problem of (...) a number of hybrid temporal logics: the basic hybrid language over transitive trees; nominal Until logic; and referential interval logic. We discuss the effects of including nominals, the @ operator, the somewhere modality E, and the difference operator D. Adding nominals to tense logic leads for several frame-classes to an increase in complexity of the satisfiability problem from PSPACE to EXPTIME. On transitive trees, however, the satisfiability problem for this language can be decided in PSPACE. Along the way we make a detour through hybrid propositional dynamic logic: we establish upper bounds for a number of temporal logics by generalizing results due to Passy and Tinchev [29] and De Giacomo [16]. We conclude with some remarks on the relevance of our results to description logic, and draw attention to the utility of the spypoint technique for proving upper and lower bounds. (shrink)

In his own writings, Rawls purposively used only a loose characterization of the basic structure, but two prominent misinterpretations highlight the current need for a more detailed account. First, G.A. Cohen argues that the Rawlsian focus on the basic structure is arbitrary due to the Rawlsian appeal to profound effects. Second, some theorists conflate the justification of coercion with the assessment of a basic structure by defining the basic structure as the coercive structure. Both misinterpretations can be corrected by carefully (...) specifying what social institutions are and explaining which social institutions come together to form the basic structure of society. (shrink)

We give an example of a countable theory $T$ such that for every cardinal $\lambda \geq \aleph_2$ there is a fully indiscernible set $A$ of power $\lambda$ such that the principal types are dense over $A$, yet there is no atomic model of $T$ over $A$. In particular, $T$ is a theory of size $\lambda$ where the principal types are dense, yet $T$ has no atomic model.

We discuss the concepts of Weyl and Riemann frames in the context of metric theories of gravity and state the fact that they are completely equivalent as far as geodesic motion is concerned. We apply this result to conformally flat spacetimes and show that a new picture arises when a Riemannian spacetime is taken by means of geometrical gauge transformations into a Minkowskian flat spacetime. We find out that in the Weyl frame gravity is described by a scalar field. We (...) give some examples of how conformally flat spacetime configurations look when viewed from the standpoint of a Weyl frame. We show that in the non-relativistic and weak field regime the Weyl scalar field may be identified with the Newtonian gravitational potential. We suggest an equation for the scalar field by varying the Einstein-Hilbert action restricted to the class of conformally-flat spacetimes. We revisit Einstein and Fokker’s interpretation of Nordström scalar gravity theory and draw an analogy between this approach and the Weyl gauge formalism. We briefly take a look at two-dimensional gravity as viewed in the Weyl frame and address the question of quantizing a conformally flat spacetime by going to the Weyl frame. (shrink)

Because of cultural differences between East and West, any attempt at outright adaptation of Western ideas in Asia will undoubtly encounter problems, if not rejection. Transferring an idea from one place to another is just like transplanting an organ from a donor to a recipient—rejection is to be expected. Human cultures respond to new ideas from different value systems in very much the same way.Recently, biomedical ethics has received much attention in Asia. Fundamental advances in medicine have motivated medical scientists (...) to look at the ethical issues arising from this progress. Will the principles upheld by the bioethicists in the West meet the challenge in Asia? This article argues that Asian bioethicists must develop a bioethics responding to their own cultural contexts. If Western principles are adopted, then they must be re-interpreted and even modified, if necessary, in light of Asian beliefs. (shrink)

This article explores the accounts of Canadian-trained health professionals working in humanitarian and development organizations who considered not treating a patient or group of patients because of resource limitations. In the narratives, not treating the patient(s) was sometimes understood as the right thing to do, and sometimes as wrong. In analyzing participants’ narratives we draw attention to how medications and equipment are represented. In one type of narrative, medications and equipment are represented primarily as scarce resources; in another, they are (...) represented as patient care. In the contexts respondents were working, medications and equipment were often both patient care interventions and scarce resources. The analytic point is that health professionals tend to emphasize one conceptualization over the other in coming to assert that not treating is right, or wrong. Rendering tacit ethical frameworks more explicit makes them available for reflection and debate. (shrink)

Despite the many successes of the relativistic quantum theory developed by Horwitz et al., certain difficulties persist in the associated covariant classical mechanics. In this paper, we explore these difficulties through an examination of the classical. Coulomb problem in the framework of off-shell electrodynamics. As the local gauge theory of a covariant quantum mechanics with evolution paratmeter τ, off-shell electrodynamics constitutes a dynamical theory of ppacetime events, interacting through five τ-dependent pre-Maxwell potentials. We present a straightforward solution of the classical (...) equations of motion, for a test event traversing the field induced by a “fixed” event (an event moving uniformly along the time axis at a fixed point in space). This solution is seen to be unsatisfactory, and reveals the essential difficulties in the formalism at the classical levels. We then offer a new model of the particle current—as a certain distribution of the event currents on the worldline—which eliminates these difficulties and permits comparison of classisical off-shell electrodynamics with the standard Maxwell theory. In this model, the “fixed” event induces a Yukawa-type potential, permitting a semiclassical identification of the pre-Maxwell time scale λ with the inverse mass of the intervening photon. Numerical solutions to the equations of motion are compared with the standard Maxwell solutions, and are seen to coincide when λ≳10−6 seconds, providing an initial estimate of this parameter. It is also demonstrated that the proposed model provides a natural interpretation for the photon mass cut-off required for the renormalizability of the off-shell quantum electrodynamics. (shrink)

Originally published in 1988, M.C. Dillon's classic study of Merleau-Ponty is now available in a revised second edition containing a new preface and a new chapter on "Truth in Art." Dillon's thesis is that Merleau-Ponty has developed the first genuine alternative to ontological dualism seen in Western philosophy. From his early work on the philosophical significance of the human body to his later ontology of flesh, Merleau-Ponty shows that the perennial problems growing out of dualistic conceptions of mind and body, (...) subject and object, immanence and transcendence can be resolved within the framework of a new way of thinking based on the exemplar of the worldly embodiment of thought. (shrink)

Since antiquity, theories of knowledge have had fundamental impacts on understanding the design of the conditions of learning and teaching. As represented in this special issue, these theories may be divided into structural, functional, and biofunctional. Structural models have contributed to knowledge about the organization of information stored in memory. Functional models have contributed to our understanding of how learning occurs and how it can be facilitated. Functional and biofunctional approaches have much in common but differ in their assumptions about (...) the nature of the role of biology in learning. All three types of theories complement one another. This paper focuses on the potential contributions of functional models, including the biofunctional model, to the design of the conditions of learning and teaching. (shrink)

A new human life comes into being not when there is mere cellular life in a human embryo, but when the newly developing body organs and systems begin to function as a whole, the author argues. This is symmetrical with the dealth of an existing human life, which occurs when its organs and systems have permanently ceased to function as a whole. Thus a new human life cannot begin until the development of a functioning brain which has begun to co-ordinate (...) and organise the activities of the body as a whole. (shrink)

Undercover filming is a method commonly used by animal activist groups to expose animal cruelty and it is important to consider the effects of publically releasing video footage of cruel practices on the viewers’ mental health. Previously, we reported that members of the Australian public were emotionally distressed soon after viewing media broadcasts of cruelty to Australian cattle exported for slaughter in Indonesia in 2011. To explore if there were any long term impacts from exposure to media on this issue, (...) a self-selecting group of 15 people who were exposed to a documentary exposé of the cruelty were re-interviewed 12 months later. Nearly all recalled their strong initial reaction to the footage. Approximately one half of the respondents who initially had had a strong emotional reaction to the footage reported negative reactions that were still strong even after this period of time. They reported potential triggers for these feelings. Of the rest, some managed to internalise their feelings. Approximately one half of respondents were unaware of continued live export exposés, suggesting less prominent media coverage. Despite the aversion and repulsion reported after viewing the initial coverage, most respondents said they would choose to watch another broadcast of animal cruelty and nearly all supported undercover investigations as a means of revealing cruelty to animals. We conclude that many people viewing footage of cruelty to animals will have long term memory of this, but that they would prefer to be informed about the issues and not be protected from them. (shrink)

Intrusive agricultural experimentspublished in New Zealand in the last five yearsare reviewed in terms of the degree of animalsuffering involved, and the necessity for thissuffering in relation to research findings.When measured against animal welfare criteriaof the Ministry of Agriculture, thirty-sixstudies inflicted ``severe'' or ``very severe''suffering. Many of these experiments hadquestionable short-term applications, had anapplication restricted to agriculturalproduction or economic growth, or could havebeen modified to prevent or reduce suffering.

We study the intersection number of families of tall ideals. We show that the intersection number of the class of analytic P-ideals is equal to the bounding number ${\mathfrak{b}}$ , the intersection number of the class of all meager ideals is equal to ${\mathfrak{h}}$ and the intersection number of the class of all F σ ideals is between ${\mathfrak{h}}$ and ${\mathfrak{b}}$ , consistently different from both.

Background: Black, Asian and minority ethnic groups have a high need for organ transplantation but deceased donation is low. This restricts the availability of well-matched organs and results in relatively long waiting times for transplantation, with increased mortality risks. Objective: To identify barriers to organ donor registration and family consent among the BAME population, and to develop and evaluate a training intervention to enhance communication with ethnic minority families and identify impacts on family consent. Methods: Three-phase programme comprising community-based research (...) involving two systematic reviews examining attitudes and barriers to organ donation and effective interventions followed by 22 focus groups with minority ethnic groups; hospital-based research examining staff practices and influences on family consent through ethics discussion groups with staff, a study on intensive care units and interviews with bereaved ethnic minority families; and development and evaluation of a training package to enhance cultural competence among ICU staff. Setting: Community focus group study in eight London boroughs with high prevalence of ethnic minority populations. Hospital studies at five NHS hospital trusts. Participants: Community studies: 228 focus group participants; hospital studies: 35 nurses, 28 clinicians, 19 hospital chaplains, 25 members of local Organ Donation Committees, 17 bereaved family members; and evaluation: 66 health professionals. Data sources: Focus groups with community residents, systematic reviews, qualitative interviews and observation in ICUs, EDGs with ICU staff, bereaved family interviews and questionnaires for trial evaluation. Review methods: Systematic review and narrative synthesis. Results: Community studies: Organ Donor Register – different ethnic/faith and age groups were at varying points on the ‘pathway’ to organ donor registration, with large numbers lacking knowledge and remaining at a pre-contemplation stage. Key attitudinal barriers were uncertainties regarding religious permissibility, bodily concerns, lack of trust in health professionals and little priority given to registration, with the varying significance of these factors varying by ethnicity/faith and age. National campaigns focusing on ethnic minorities have had limited impact, whereas characteristics of effective educational interventions are being conducted in a familiar environment; addressing the groups’ particular concerns; delivery by trained members of the lay community; and providing immediate access to registration. Interventions are also required to target those at specific stages of the donation pathway. Hospital studies: family consent to donation – many ICU staff, especially junior nurses, described a lack of confidence in communication and supporting ethnic minority families, often reflecting differences in emotional expression, faith and cultural beliefs, and language difficulties. The continuing high proportion of family donation discussions that take place without the collaboration of a specialist nurse for organ donation reflected consultants’ views of their own role in family consent to donation, a lack of trust in SNODs and uncertainties surrounding controlled donations after circulatory death. Hospital chaplains differed in their involvement in ICUs, reflecting their availability/employment status, personal interests and the practices of ICU staff. Evaluation: professional development package – a digital versatile disk-based training package was developed to promote confidence and skills in cross-cultural communication. Initial evaluation produced positive feedback and significant affirmative attitudinal change but no significant difference in consent rate over the short follow-up period with requirements for longer-term evaluation. Limitations: Participants in the focus group study were mainly first-generation migrants of manual socioeconomic groups. It was not permitted to identify non-consenting families for interview with data regarding the consent process were therefore limited to consenting families. Conclusions: The research presents guidance for the effective targeting of donation campaigns focusing on minority ethnic groups and provides the first training package in cultural competence in the NHS. Future work: Greater evaluation is required of community interventions in the UK to enhance knowledge of effective practice and analysis of the experiences of non-consenting ethnic minority families. Funding: The National Institute for Health Research Programme Grants for Applied Research programme. (shrink)

Open peer commentary on the target article “Arguments Opposing the Radicalism of Radical Constructivism” by Gernot Saalmann. First paragraph: I appreciate Saalmann’s recognition that “there are considerable differences amongst the authors” and that these “have changed their opinions in the course of time” (§3); but given this, what are the consequences for an outline of the theses of radical constructivism (RC)? Which approach is best for outlining a theory of knowing under these hindering conditions? My suggestion would be to use (...) a method specifically developed for this kind of situation and to present it explicitly, or, if it does not yet exist, to develop one. (shrink)

Open peer commentary on the target article “Who Conceives of Society?” by Ernst von Glasersfeld. First paragraph: Issues such as social interaction and communication play an essential role in my recent approach to knowledge management called “Knowledge Cooperation”, conceived as “the participative cultivation of knowledge in a voluntary, informal social group”. Radical Constructivism provides a substantial support to the foundations of this approach, which aims at equilibrating intellectual and social capital. So I warmly welcome Ernst von Glasersfeld’s clarification of the (...) constructivist position in regard to “society.”. (shrink)

Open peer commentary on the article “Constructivism and Computation: Can Computer-Based Modeling Add to the Case for Constructivism?” by Manfred Füllsack. Upshot: Füllsack’s article offers many interesting ideas but falls short of elucidating the relationship between constructivism and computation. It could profit by taking into consideration stronger constructivist foundations such as the distinction between machine and organism, the relationship between reality and the observer, and Ceccato’s theory of attention.