Deep brain stimulation of the subthalamic nucleus is a clinically effective tool for treating medically refractory Parkinson’s disease, but its neural mechanisms remain debated. Previous work has demonstrated that STN DBS results in evoked potentials in the primary motor cortex, suggesting that modulation of cortical physiology may be involved in its therapeutic effects. Due to technical challenges presented by high-amplitude DBS artifacts, these EPs are often measured in response to low-frequency stimulation, which is generally ineffective at PD symptom management. This (...) study aims to characterize STN-to-cortex EPs seen during clinically relevant high-frequency STN DBS for PD. Intraoperatively, we applied STN DBS to 6 PD patients while recording electrocorticography from an electrode strip over the ipsilateral central sulcus. Using recently published techniques, we removed large stimulation artifacts to enable quantification of STN-to-cortex EPs. Two cortical EPs were observed – one synchronized with DBS onset and persisting during ongoing stimulation, and one immediately following DBS offset, here termed the “start” and the “end” EPs respectively. The start EP is, to our knowledge, the first long-latency cortical EP reported during ongoing high-frequency DBS. The start and end EPs differ in magnitude and latency, and the end, but not the start, EP magnitude has a significant relationship to ongoing high gamma power during the EP. These contrasts may suggest mechanistic or circuit differences in EP production during the two time periods. This represents a potential framework for relating DBS clinical efficacy to the effects of a variety of stimulation parameters on EPs. (shrink)

This essay is an attempt to point up the gap between, on the one hand, the methods currently available to the biologist in the laboratory and, on the other, the kind of data that he or she would need in order to characterise genetically engineered proteins of topical biological interest in such a way as to make use of the techniques of protein engineering.

We examine three critical aspects of Popper’s formulation of the ‘ Logic of Scientific Discovery ’—evidence, content and degree of corroboration—and place these concepts in the context of the Tree of Life (ToL) problem with particular reference to molecular systematics. Content, in the sense discussed by Popper, refers to the breadth and scope of existence that a hypothesis purports to explain. Content, in conjunction with the amount of available and relevant evidence, determines the testability, or potential degree of corroboration, of (...) a statement; content distinguishes scientific hypotheses from metaphysical assertions. Degree of corroboration refers to the relative and tentative confidence assigned to one hypothesis over another, based upon the performance of each under critical tests. Here we suggest that systematists attempt to maximize content and evidence to increase the potential degree of corroboration in all phylogenetic endeavors. Discussion of this “total evidence” approach leads to several interesting conclusions about generating ToL hypotheses. (shrink)

This paper introduces the notion of syntactic feature to provide a unified treatment of earlier model theoretic proofs of both the compactness and interpolation theorems for a variety of two valued logics including sentential logic, first order logic, and a family of modal sentential logic includingM,B,S 4 andS 5. The compactness papers focused on providing a proof of the consequence formulation which exhibited the appropriate finite subset. A unified presentation of these proofs is given by isolating their essential feature and (...) presenting it as an abstract principle about syntactic features. The interpolation papers focused on exhibiting the interpolant. A unified presentation of these proofs is given by isolating their essential feature and presenting it as a second abstract principle about syntactic features. This second principle reduces the problem of exhibiting the interpolant to that of establishing the existence of a family of syntactic features satisfying certain conditions. The existence of such features is established for a variety of logics (including those mentioned above) by purely combinatorial arguments. (shrink)

Association between sister chromatids is essential for their attachment and segregation to opposite poles of the spindle in mitosis and meiosis II. Sister‐chromatid cohesion is also likely to be involved in linking homologous chromosomes together in meiosis I. Cytological observations provide evidence that attachment between sister chromatids is different in meiosis and mitosis and suggest that cohesion between the chromatid arms may differ mechanistically from that at the centromere. The physical nature of cohesion is addressed, and proteins that are candidates (...) for holding sister chromatids together are discussed. Dissolution of sister‐chromatid cohesion must be regulated precisely, and potential mechanisms to release cohesion are presented. (shrink)

Senior managers are important to the successful management of ethics in organizations. Therefore, their perceptions of organizational ethics are important. In this study, we propose that senior managers are likely to have a more positive perception of organizational ethics than lower level employees do largely because of their managerial role and their corresponding identification with the organization and need to protect the organization’s image as well as their own identity. By contrast, lower level employees are more likely to be cynical (...) about the organization’s ethics. In order to compare senior managers’ and lower level employees’ perceptions of ethics in the organization, we surveyed randomly selected senior managers and lower level employees in three firms. We found that perceptions of ethics in the organization differed predictably across levels, with senior managers’ perceptions being significantly more positive and lower level employees’ perceptions being more negative. Implications for practice and research are discussed. (shrink)

It is often assumed that engaging in a one‐on‐one dialogue with a tutor is more effective than listening to a lecture or reading a text. Although earlier experiments have not always supported this hypothesis, this may be due in part to allowing the tutors to cover different content than the noninteractive instruction. In 7 experiments, we tested the interaction hypothesis under the constraint that (a) all students covered the same content during instruction, (b) the task domain was qualitative physics, (c) (...) the instruction was in natural language as opposed to mathematical or other formal languages, and (d) the instruction conformed with a widely observed pattern in human tutoring: Graesser, Person, and Magliano's 5‐step frame. In the experiments, we compared 2 kinds of human tutoring (spoken and computer mediated) with 2 kinds of natural‐language‐based computer tutoring (Why2‐Atlas and Why2‐AutoTutor) and 3 control conditions that involved studying texts. The results depended on whether the students' preparation matched the content of the instruction. When novices (students who had not taken college physics) studied content that was written for intermediates (students who had taken college physics), then tutorial dialogue was reliably more beneficial than less interactive instruction, with large effect sizes. When novices studied material written for novices or intermediates studied material written for intermediates, then tutorial dialogue was not reliably more effective than the text‐based control conditions. (shrink)

Ogni tentativo di ripensare le nostre categorie politiche deve muovere dalla consapevolezza che della distinzione classica fra zoé e bios, tra vita naturale ed esistenza politica (o tra l'uomo come semplice vivente e l'uomo come soggetto politico), non ne sappiamo piú nulla. Nel diritto romano arcaico homo sacer era un uomo che chiunque poteva uccidere senza commettere omicidio e che non doveva però essere messo a morte nelle forme prescritte dal rito. È la vita uccidibile e insacrificabile dell' 'uomo sacro' (...) a fornire qui la chiave per una rilettura critica della nostra tradizione politica. Quando la vita diventa la posta in gioco della politica e questa si trasforma in biopolitica, tutte le categorie fondamentali della nostra riflessione, dai diritti dell'uomo alla democrazia alla cittadinanza, entrano in un processo di svuotamento e di dislocazione il cui risultato sta oggi davanti ai nostri occhi. Seguendo il filo del rapporto costitutivo fra nuda vita e potere sovrano, da Aristotele ad Auschwitz, dall'Habeas corpus alle Dichiarazioni dei diritti, il libro di Agamben cerca di decifrare gli enigmi - prima di tutti il fascismo e il nazismo - che il nostro secolo ha proposto alla ragione storica. Fino a vedere, nel campo di concentramento, il paradigma biopolitico nascosto della modernità in cui città e casa sono diventate indiscernibili e la possibilità di distinguere tra il nostro corpo biologico e il nostro corpo politico ci è stata tolta una volta per tutte. (shrink)

I show how Sir William Rowan Hamilton’s philosophical commitments led him to a causal interpretation of classical mechanics. I argue that Hamilton’s metaphysics of causation was injected into his dynamics by way of a causal interpretation of force. I then detail how forces are indispensable to both Hamilton’s formulation of classical mechanics and what we now call Hamiltonian mechanics (i.e., the modern formulation). On this point, my efforts primarily consist of showing that the contemporary orthodox interpretation of potential energy is (...) the interpretation found in Hamilton’s work. Hamilton called the potential energy function the “force-function” because he believed that it represents forces at work in the world. Various non-historical arguments for this orthodox interpretation of potential energy are provided, and matters are concluded by showing that in classical Hamiltonian mechanics, facts about the potential energies of systems are grounded in facts about forces. Thus, if one can tolerate the view that forces are causes of motion, then Hamilton provides one with a road map for transporting causation into one of the most mathematically sophisticated formulations of classical mechanics, viz., Hamiltonian mechanics. (shrink)

We report on the small-scale (0.5 13 h - 1M, a large-scale bias of ~2.0 and a satellite fraction of 12 ± 2 per cent. Thus, these galaxies occupy haloes with average masses in between those of the higher redshift BOSS CMASS sample and the original SDSS I/II luminous red galaxy sample © 2012 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society © doi:10.1093/mnras/sts314.

This empirical study of Fortune 1000 firms assesses the degree to which those firms have adopted various practices associated with corporate ethics programs. The study examines the following aspects of formalized corporate ethics activity: ethics-oriented policy statements; formalization of management responsibilities for ethics; free-standing ethics offices; ethics and compliance telephone reporting/advice systems; top management and departmental involvement in ethics activities; usage of ethics training and other ethics awareness activities; investigatory functions; and evaluation of ethics program activities. Results show a high (...) degree of corporate adoption of ethics policies, but wide variability in the extent to which these policies are implemented by various supporting structures and managerial activities. In effect, the vast majority of firms have committed to the low cost, possibly symbolic side of ethics management (e.g., adoption of ethics codes and policies, etc.). But firms differ substantially in their efforts to see that those policies or codes actually are put into practice. (shrink)