University of Ottawa

About: University of Ottawa is a education organization based out in Ottawa, Ontario, Canada. It is known for research contribution in the topics: Population & Health care. The organization has 36763 authors who have published 87034 publications receiving 2913651 citations. The organization is also known as: uOttawa & U of O.

A universal model for spike-frequency adaptation

Abstract: Spike-frequency adaptation is a prominent feature of neural dynamics. Among other mechanisms, various ionic currents modulating spike generation cause this type of neural adaptation. Prominent examples are voltage-gated potassium currents (M-type currents), the interplay of calcium currents and intracellular calcium dynamics with calcium-gated potassium channels (AHP-type currents), and the slow recovery from inactivation of the fast sodium current. While recent modeling studies have focused on the effects of specific adaptation currents, we derive a universal model for the firing-frequency dynamics of an adapting neuron that is independent of the specific adaptation process and spike generator. The model is completely defined by the neuron's onset f-I curve, the steady-state f-I curve, and the time constant of adaptation. For a specific neuron, these parameters can be easily determined from electrophysiological measurements without any pharmacological manipulations. At the same time, the simplicity of the model allows one to analyze mathematically how adaptation influences signal processing on the single-neuron level. In particular, we elucidate the specific nature of high-pass filter properties caused by spike-frequency adaptation. The model is limited to firing frequencies higher than the reciprocal adaptation time constant and to moderate fluctuations of the adaptation and the input current. As an extension of the model, we introduce a framework for combining an arbitrary spike generator with a generalized adaptation current.

The rise of 3-d single-ion magnets in molecular magnetism: towards materials from molecules?

Abstract: Single-molecule magnets (SMMs) that contain one spin centre (so-called single-ion magnets) theoretically represent the smallest possible unit for spin-based electronic devices. The realisation of this and related technologies, depends on first being able to design systems with sufficiently large energy barriers to magnetisation reversal, Ueff, and secondly, on being able to organise these molecules into addressable arrays. In recent years, significant progress has been made towards the former goal - principally as a result of efforts which have been directed towards studying complexes based on highly anisotropic lanthanide ions, such as Tb(iii) and Dy(iii). Since 2013 however, and the remarkable report by Long and co-workers of a linear Fe(i) system exhibiting Ueff = 325 K, single-ion systems of transition metals have undergone something of a renaissance in the literature. Not only do they have important lessons to teach us about anisotropy and relaxation dynamics in the quest to enhance Ueff, the ability to create strongly coupled spin systems potentially offers access to a whole of host of 1, 2 and 3-dimensional materials with interesting structural and physical properties. This perspective summarises recent progress in this rapidly expanding sub-genre of molecular magnetism from the viewpoint of the synthetic chemist, with a particular focus on the lessons that have so far been learned from single-ion magnets of the d-block, and, the future research directions which we feel are likely to emerge in the coming years.

Facilitating second language listening comprehension: acquiring successful strategies

Abstract: This paper presents arguments for an emphasis on listening comprehen- sion in language learning/teaching. An explanation of how listeners can use strategies to enhance the learning process is presented, with a review of the existing research base on how second language listening is taught. The major part of the paper presents and discusses pedagogical re- commendations, as well as examples of performance checklists for de- veloping metacognitive awareness. Introduction Listening comprehension is anything but a passive activity. It is a complex, active process in which the listener must discriminate between sounds, understand vocabulary and grammatical structures, interpret stress and intonation, retain what was gathered in all of the above, and interpret it within the immediate as well as the larger sociocultural context of the utterance. Co-ordinating all of this involves a great deal of mental activity on the part of the listener. Listening is hard work, and deserves more analysis and support. Listening comprehension as a separate and important component of language learning only came into focus after significant debate about its validity. Recent research has demonstrated the critical role of language input in language learning (e.g. Dunkel 1991, Feyten 1991), providing support for the primacy of listening comprehension in instructional methods. This has led Dunkel to assert that the study of listening comprehension has become the 'polestar' of second language acquisition theory building, research, and pedagogy. This paper will explain how listening comprehension can enhance the process of language learning/acquisition, how listeners can use strategies to facilitate that process, and how teachers can nurture the development of these strategies. Listening As mentioned above, it is now generally recognized that listening comprehension comprehension plays a key role in facilitating language learning. and language According to Gary (1975) giving pre-eminence to listening comprehen- learning sion, particularly in the early stages of second language teaching/ learning, provides advantages of four different types: cognitive, efficiency, utility, and affective. The cognitive advantage of an initial

Evolution of Wenger's concept of community of practice

Abstract: In the experience of health professionals, it appears that interacting with peers in the workplace fosters learning and information sharing. Informal groups and networks present good opportunities for information exchange. Communities of practice (CoPs), which have been described by Wenger and others as a type of informal learning organization, have received increasing attention in the health care sector; however, the lack of uniform operating definitions of CoPs has resulted in considerable variation in the structure and function of these groups, making it difficult to evaluate their effectiveness. To critique the evolution of the CoP concept as based on the germinal work by Wenger and colleagues published between 1991 and 2002. CoP was originally developed to provide a template for examining the learning that happens among practitioners in a social environment, but over the years there have been important divergences in the focus of the concept. Lave and Wenger's earliest publication (1991) centred on the interactions between novices and experts, and the process by which newcomers create a professional identity. In the 1998 book, the focus had shifted to personal growth and the trajectory of individuals' participation within a group (i.e., peripheral versus core participation). The focus then changed again in 2002 when CoP was applied as a managerial tool for improving an organization's competitiveness. The different interpretations of CoP make it challenging to apply the concept or to take full advantage of the benefits that CoP groups may offer. The tension between satisfying individuals' needs for personal growth and empowerment versus an organization's bottom line is perhaps the most contentious of the issues that make CoPs difficult to cultivate. Since CoP is still an evolving concept, we recommend focusing on optimizing specific characteristics of the concept, such as support for members interacting with each other, sharing knowledge, and building a sense of belonging within networks/teams/groups. Interventions that facilitate relationship building among members and that promote knowledge exchange may be useful for optimizing the function of these groups.

Brown adipose tissue thermogenesis: interdisciplinary studies.

Abstract: Energy expenditure for thermogenesis in brown adipose tissue (BAT) serves either to maintain body temperature in the cold or to waste food energy. It has roles in thermal balance and energy balance, and when defective, is usually associated with obesity. BAT can grow or atrophy; it is usually atrophied in obese animals. Control of BAT thermogenesis and growth is by the sympathetic nervous system, with integration of signals in the hypothalamus. Sensory nerves may also be involved. Understanding the control of growth and differentiation of BAT is important for discovering how to reactivate it is obesity. Studies on control of gene expression in BAT are concentrating on thermogenically important components such as the uncoupling protein (which allows BAT mitochondria to operate in a thermogenic uncoupled mode), lipoprotein lipase (which allows BAT to compete with white adipose tissue for dietary lipid), and thyroxine 5'-deiodinase (which allows endogenous triiodothyronine generation, part of the control of ...