TheK-trivial sets form an ideal in the Turing degrees, which is generated by its computably enumerable members and has an exact pair below the degree of the halting problem. The question of whether it has an exact pair in the c.e. degrees was first raised in [22, Question 4.2] and later in [25, Problem 5.5.8].We give a negative answer to this question. In fact, we show the following stronger statement in the c.e. degrees. There exists aK-trivial degreedsuch that for all (...) degreesa, bwhich are notK-trivial anda > d, b > dthere exists a degreevwhich is notK-trivial anda > v, b > v. This work sheds light to the question of the definability of theK-trivial degrees in the c.e. degrees. (shrink)

For a set A of non-negative integers, let D be the set of non-negative differences of elements of A. Clearly, if A is computable, then D is computably enumerable. We show that every simple set which contains 0 is the difference set of some computable set and that every computably enumerable set is computably isomorphic to the difference set of some computable set. Also, we prove that there is a computable set which is the difference set of the complement of (...) some computably enumerable set but not of any computably enumerable set. Finally, we show that every arithmetic set is in the Boolean algebra generated from the computable sets by the difference operator D and the Boolean operations. (shrink)

We study inversions of the jump operator on ${\mathrm{\Pi }}_{1}^{0}$ classes, combined with certain basis theorems. These jump inversions have implications for the study of the jump operator on the random degrees—for various notions of randomness. For example, we characterize the jumps of the weakly 2-random sets which are not 2-random, and the jumps of the weakly 1-random relative to 0′ sets which are not 2-random. Both of the classes coincide with the degrees above 0′ which are not 0′-dominated. A (...) further application is the complete solution of [24, Problem 3.6.9]: one direction of van Lambalgen's theorem holds for weak 2-randomness, while the other fails. Finally we discuss various techniques for coding information into incomplete randoms. Using these techniques we give a negative answer to [24, Problem 8.2.14]: not all weakly 2-random sets are array computable. In fact, given any oracle X, there is a weakly 2-random which is not array computable relative to X. This contrasts with the fact that all 2-random sets are array computable. (shrink)

The human immune system can directly lyse invading micro‐organisms and aberrant host cells by generating pores in the cell envelope, called membrane attack complexes (MACs). Recent studies using single‐particle cryoelectron microscopy have revealed that the MAC is an asymmetric, flexible pore and have provided a structural basis on how the MAC ruptures single lipid membranes. Despite these insights, it remains unclear how the MAC ruptures the composite cell envelope of Gram‐negative bacteria. Recent functional studies on Gram‐negative bacteria elucidate (...) that local assembly of MAC pores by surface‐bound C5 convertase enzymes is essential to stably insert these pores into the bacterial outer membrane (OM). These convertase‐generated MAC pores can subsequently efficiently damage the bacterial inner membrane (IM), which is essential for bacterial killing. This review summarizes these recent insights of MAC assembly and discusses how MAC pores kill Gram‐negative bacteria. Furthermore, this review elaborates on how MAC‐dependent OM damage could lead to IM destabilization, which is currently not well understood. A better understanding on how MAC pores kill bacteria could facilitate the future development of novel strategies to treat infections with Gram‐negative bacteria. (shrink)

Effectiveness is a key criterion in assessing the justification of antibiotic resistance interventions. Depending on an intervention’s effectiveness, burdens and costs will be more or less justified, which is especially important for large scale population-level interventions with high running costs and pronounced risks to individuals in terms of wellbeing, integrity and autonomy. In this paper, we assess the case of routine hospital screening for multi-drug-resistant Gram-negative bacteria (MDRGN) from this perspective. Utilizing a comparison to screening programs for Methicillin-Resistant Staphylococcus aureus (...) (MRSA) we argue that current screening programmes for MDRGN in low endemic settings should be reconsidered, as its effectiveness is in doubt, while general downsides to screening programs remain. To accomplish justifiable antibiotic stewardship, MDRGN screening should not be viewed as a separate measure, but rather as part of a comprehensive approach. The program should be redesigned to focus on those at risk of developing symptomatic infections with MDRGN rather than merely detecting those colonised. (shrink)

The pathogenic, Gram‐negative bacteria, Neisseria gon‐orrhoeae, Neisseria meningitidis and Haemophilus influenzae, secrete immunoglobulin A1 proteases into their extracellular surroundings. An extraordinary feature in the secretory pathway of these putative virulence factors is a self‐directed outer membrane transport step allowing the proteins to be secreted autonomously, even from foreign Gram‐negative host cells like Escherichia coli. Here we summarize recent achievements in the understanding of IgA protease outer membrane translocation.

An important question for bacterial cell division is how the invaginating septum can overcome the turgor force generated by the high osmolarity of the cytoplasm. I suggest that it may not need to. Several studies in Gram‐negative bacteria have shown that the periplasm is isoosmolar with the cytoplasm. Indirect evidence suggests that this is also true for Gram‐positive bacteria. In this case the invagination of the septum takes place within the uniformly high osmotic pressure environment, and does not have (...) to fight turgor pressure. A related question is how the V‐shaped constriction of Gram‐negative bacteria relates to the plate‐like septum of Gram‐positive bacteria. I collected evidence that Gram‐negative bacteria have a latent capability of forming plate‐like septa, and present a model in which septal division is the basic mechanism in both Gram‐positive and Gram‐negative bacteria. (shrink)

From the myths of the ancient world to the Middle Ages to Darwin and beyond, Preece captures the most telling and fascinating accounts of humankind's ...

In Part 1 the reader is introduced to some standard systems of modal logic and encouraged through a series of exercises to become proficient in manipulating these logics. The emphasis is on possible world semantics for modal logics and the semantic emphasis is carried into the formal method, Jeffrey-style truth-trees. Standard truth-trees are extended in a simple and transparent way to take possible worlds into account. Part 2 systematically explores the applications of modal logic to philosophical issues such as truth, (...) time, processes, knowledge and belief, obligation and permission. Accessible, authoritative, and assured, Modal Logics and Philosophy requires no more background than the completion of a standard introductory logic course. It will be welcomed not only by students looking for a bridge between introductory logic texts and the high-level technical literature but as a guide to, and exploration of, work at the forefront of logic and philosophy. (shrink)

Despite the evidence showing the promise of HIV treatment as prevention (TasP) in reducing HIV incidence, a variety of ethical questions surrounding the implementation and “scaling up” of TasP have been articulated by a variety of stakeholders including scientists, community activists and government officials. Given the high profile and potential promise of TasP in combatting the global HIV epidemic, an explicit and transparent research priority-setting process is critical to inform ongoing ethical discussions pertaining to TasP.

The first edition, published by Acumen in 2000, became a prescribed textbook on modal logic courses. The second edition has been fully revised in response to readers' suggestions, including two new chapters on conditional logic, which was not covered in the first edition. "Modal Logics and Philosophy" is a fully comprehensive introduction to modal logics and their application suitable for course use. Unlike most modal logic textbooks, which are both forbidding mathematically and short on philosophical discussion, "Modal Logics and Philosophy" (...) places its emphasis firmly on showing how useful modal logic can be as a tool for formal philosophical analysis. In part 1 of the book, the reader is introduced to some standard systems of modal logic and encouraged through a series of exercises to become proficient in manipulating these logics. The emphasis is on possible world semantics for modal logics and the semantic emphasis is carried into the formal method, Jeffrey-style truth-trees. Standard truth-trees are extended in a simple and transparent way to take possible worlds into account. Part 2 systematically explores the applications of modal logic to philosophical issues such as truth, time, processes, knowledge and belief, obligation and permission. (shrink)

Philosophical arguments stemming from the public health ethics arena suggest that public health interventions ought to be subject to normative inquiry that considers relational values, including concepts such as solidarity, reciprocity and health equity. As yet, however, the extent to which ‘public’ values influence the ‘autonomous’ decisions of the public remains largely unexplored. Drawing on interviews with 50 men in Vancouver, Canada, this study employs a critical discourse analysis to examine participants’ decisions and motivations to voluntarily access HIV testing and/or (...) to accept a routine HIV test offer. Within a sub-set of interviews, a transactional discourse emerged in which the decision to test features an arrangement of ‘giving and receiving’. Discourses related to notions of solidarity emphasize considerations of justice and positions testing as a ‘public’ act. Lastly, ‘individualistic’ discourses focused on individual-level considerations, with less concern for the broader public ‘good’. These findings underscore how normative dimensions pertaining to men’s decisions to test are dialectically interrelated with the broader social and structural influences on individual and collective health-related behaviour, thereby suggesting a need to advance an explicit empirical-normative research agenda related to population and public health intervention research. (shrink)

Laura Grams - Language and Learning: Philosophy of Language in the Hellenistic Age - Journal of the History of Philosophy 45:1 Journal of the History of Philosophy 45.1 153-154 Muse Search Journals This Journal Contents Reviewed by Laura Grams University of Nebraska at Omaha Dorothea Frede and Brad Inwood, editors. Language and Learning: Philosophy of Language in the Hellenistic Age. Cambridge-New York: Cambridge University Press, 2005. Pp. xi + 353. Cloth, $90.00. This collection of papers on Hellenistic philosophy of language (...) resulted from the ninth Symposium Hellenisticum, held in Hamburg in July 2001. It makes an important contribution to the secondary literature on this topic and will be valuable to anyone who studies Hellenistic philosophy. Because some chapters discuss broader issues in the philosophy of language or connect.. (shrink)

Secondary English is a comprehensive introduction to the theory and practice of teaching English in secondary schools for pre-service teachers. Written by highly accomplished English teachers, the book's practical approach to language, literacy and literature, fosters the skills of assessment, unit planning and teaching strategies.

The usual treatment of a dinner table utterance of ‘Can you pass the salt?’ is that it involves an indirect request to pass the salt as well as a direct question about the hearer’s ability to do so: an indirect speech act. These are held to involve two illocutionary forces and two illocutionary acts. Rod Bertolet has raised doubts about whether consideration of such examples warrants the postulation of indirect speech acts and illocutionary forces other than the literal ones. In (...) a recent article, Mary Kate McGowan, Shan Shan Tam, and Margaret Hall claim to show that these doubts are unfounded. The purpose of this paper is to show that they have not established this. (shrink)

Traces the development of recursive functions from their origins in the late nineteenth century to the mid-1930s, with particular emphasis on the work and influence of Kurt Gödel.

First Published in 2003. Routledge is an imprint of Taylor & Francis, an informa company.

Ever since Saul Kripke and others developed a semantic interpretation for modal logic, 'possible worlds' has been a much debated issue in contemporary metaphysics. To propose the idea of a possible world that differs in some way from our actual world - for example a world where the grass is red or where no people exist - can help us to analyse and understand a wide range of philosophical concepts, such as counterfactuals, properties, modality, and of course, the notions of (...) possibility and necessity. This book examines the ways in which possible worlds have been used as a framework for considering problems in logic and argument analysis. The book begins with a non-technical introduction to the basic ideas of modal logic in terms of Kripke's possible worlds and then moves on to a discussion of 'possible for' and 'possible that'. The central chapters examine questions of meaning, epistemic possibility, temporal logic, metaphysics, and impossibility. Girle also investigates how the idea of a possible world can be put to use in different areas of philosophy, the problems it may raise, and the benefits that can be gained. (shrink)

Ever since Saul Kripke and others developed a semantic interpretation for modal logic, 'possible worlds' has been a much debated issue in contemporary metaphysics. To propose the idea of a possible world that differs in some way from our actual world - for example a world where the grass is red or where no people exist - can help us to analyse and understand a wide range of philosophical concepts, such as counterfactuals, properties, modality, and of course, the notions of (...) possibility and necessity. This book examines the ways in which possible worlds have been used as a framework for considering problems in logic and argument analysis. The book begins with a non-technical introduction to the basic ideas of modal logic in terms of Kripke's possible worlds and then moves on to a discussion of 'possible for' and 'possible that'. The central chapters examine questions of meaning, epistemic possibility, temporal logic, metaphysics, and impossibility. Girle also investigates how the idea of a possible world can be put to use in different areas of philosophy, the problems it may raise, and the benefits that can be gained. (shrink)

Moral relativism is a tragedy and cognitive relativism is a farce – so Gellner argues. First the tragedy: moral relativism is consistent and compelling given moral diversity and contention worldwide. Then the farce: cognitive relativism is self-contradictory and logically false; it is also absurd in view of hard science, which gets testable, cumulative, applicable results that yield high tech; and it is insidious – where logical consistency and empirical accuracy are a dead letter, mummery rules.

Hysteresis means literally “that which comes later,” being derived from the Greek verb ύστερέω. Thus, hysteresis effects, generally defined, are those that persist after the initial causes giving rise to the effects are removed. During the course of the 1980s, it became increasingly fashionable to invoke hysteresis effects to explain economic phenomena. Two of the main areas of application were to unemployment and international trade. In the case of unemployment, distinctive features of labor markets, such as social norms that rule (...) out wage-cutting in the face of rising unemployment, imply that “increases in unemployment have a direct impact on the ‘natural’ rate of unemployment”. The implication for macroeconomic systems is that “temporary shocks can have a permanent effect on the level of employment”. In the case of international trade, hysteresis effects arise from the industrial economics of sunk costs: “the argument is that firms must incur sunk costs to enter new markets, and cannot recoup these costs if they exit.… thus foreign firms that entered the U.S. market when the dollar was high do not abandon their sunk cost investments when the dollar falls.” The implication for trade flows is “an effect which persists after the cause that brought it about has been removed”. (shrink)

We prove that there exists a noncomputable c.e. real which is low for weak 2-randomness, a definition of randomness due to Kurtz, and that all reals which are low for weak 2-randomness are low for Martin-Löf randomness.