5,466 research outputs found

    Interplanetary Particle Environment. Proceedings of a Conference

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    A workshop entitled the Interplanetary Charged Particle Environment was held at the Jet Propulsion Laboratory (JPL) on March 16 and 17, 1987. The purpose of the Workshop was to define the environment that will be seen by spacecraft operating in the 1990s. It focused on those particles that are involved in single event upset, latch-up, total dose and displacement damage in spacecraft microelectronic parts. Several problems specific to Magellan were also discussed because of the sensitivity of some electronic parts to single-event phenomena. Scientists and engineers representing over a dozen institutions took part in the meeting. The workshop consisted of two major activities, reviews of the current state of knowledge and the formation of working groups and the drafting of their reports

    Dendritic cable with active spines: a modeling study in the spike-diffuse-spike framework

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    The spike-diffuse-spike (SDS) model describes a passive dendritic tree with active dendritic spines. Spine-head dynamics is modelled with a simple integrate-and-fire process, whilst communication between spines is mediated by the cable equation. Here we develop a computational framework that allows the study of multiple spiking events in a network of such spines embedded in a simple one-dimensional cable. This system is shown to support saltatory waves as a result of the discrete distribution of spines. Moreover, we demonstrate one of the ways to incorporate noise into the spine-head whilst retaining computational tractability of the model. The SDS model sustains a variety of propagating patterns

    The Problem of Mind-Body Dichotomy: A Critique of the Cartesian Approach

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    The mind-body problem is a perennial philosophical problem that seeks to uncover the relationship or causal interaction that exists between the corporeal and incorporeal aspects of the human person. It thrives under the assumption that the human person is made up of two distinct entities, that is, mind and body, which explains their assumed causal relation. As attractive as this may seem, not all philosophers agree to this feigned idea of interaction and bifurcation of the human person. One philosopher of note, who sorts to address this problem in the 17th century, is René Descartes. For Descartes, minds and bodies are distinct kinds of substance, where bodies are spatially extended substances (a res extensa) and minds are unexpended substances characterised primarily by thought (a res cogitans). But, if minds and bodies are radically dissimilar, how could they causally interact? This paper therefore attempts to examine the philosophical foundations of Cartesian dualism. It also articulates the major arguments adopted by Descartes through his methodic doubts to address the mind-body problem. The paper concludes by highlighting some fundamental criticisms of Cartesian Interactionism in the light of recent trends in parapsychology and neuro-scientific research

    Depletion of mitochondria in mammalian cells through enforced mitophagy

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    Mitochondria are not only the 'powerhouse' of the cell; they are also involved in a multitude of processes that include calcium storage, the cell cycle and cell death. Traditional means of investigating mitochondrial importance in a given cellular process have centered upon depletion of mtDNA through chemical or genetic means. Although these methods severely disrupt the mitochondrial electron transport chain, mtDNA-depleted cells still maintain mitochondria and many mitochondrial functions. Here we describe a straightforward protocol to generate mammalian cell populations with low to nondetectable levels of mitochondria. Ectopic expression of the ubiquitin E3 ligase Parkin, combined with short-term mitochondrial uncoupler treatment, stimulates widespread mitophagy and effectively eliminates mitochondria. In this protocol, we explain how to generate Parkin-expressing, mitochondria-depleted cells from scratch in 23 d, as well as offer a variety of methods for confirming mitochondrial clearance. Furthermore, we describe culture conditions to maintain mitochondrial-depleted cells for up to 30 d with minimal loss of viability, for longitudinal studies. This method should prove useful for investigating the importance of mitochondria in a variety of biological processes

    Journal of African Christian Biography: v. 3, no. 1

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    A publication of the Dictionary of African Christian Biography with U.S. offices located at the Center for Global Christianity and Mission at Boston University. This issue focuses on: 1. “Creole Saga”: The Gambia’s Liberated African Community in the 19th Century: The Stories of J. A. B. Horton, G. C. Nicol, J. R. Maxwell, and J. D. Richards by Asi Florence Mahoney. Introduction by Gabriel Leonard Allen. 2. The Contribution of Daniel William Alexander to the Birth and Growth of Eastern Orthodoxy in East Africa. 3. Biographies by Stephan Hayes and Louise Pirouet. Introduction by Fr. Evangelos Thiani. 4. Recent Print and Digital Resources Related to Christianity in Africa

    A feasibility study on using inkjet technology, micropumps, and MEMs as fuel injectors for bipropellant rocket engines

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    Control over drop size distributions, injection rates, and geometrical distribution of fuel and oxidizer sprays in bi-propellant rocket engines has the potential to produce more efficient, more stable, less polluting rocket engines. This control also offers the potential of an engine that can be throttled, working efficiently over a wide range of output thrusts. Inkjet printing technologies, MEMS fuel atomizers, and piezoelectric injectors similar in concept to those used in diesel engines are considered for their potential to yield a new, more active injection scheme for a rocket engine. Inkjets are found to be unable to pump at sufficient pressures, and have possibly dangerous failure modes. Active injection is found to be feasible if high pressure drop along the injector plate are used. A conceptual design is presented and its basic behavior assessed

    Of Solemn Oaths and Obligations: The Environmental Impact of the ICJ’s Decision in the Case of the Gabcikovo-Nagymaros Project

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    Chapter Extract: The law of treaties often conjures up images of states as rotund gentlemen with whiskers, vests, and watch-chains proclaiming solemn and chivalric oaths upon their honour. Treaties are sacred in the same way that a man\u27s word is his bond. This type of relationship among states is largely unquestioned since much of the way we live in the world depends upon the assumption of the inviolability of sovereign states and their treaties. Any challenge to these assumptions would surely evoke horror at the unmentionable void that would result-except in lawyers who make their livings shaving nuances. However, in the context of the environment, the analogy between states and barons begins to break down. Environmental impacts flow unimpeded across the boundaries of sovereign states, without respect for body or boundary. People form alliances across borders in order to pursue broader, more global issues. Support for adding the environment to the list of concerns that may justify interference in the affairs of neighbouring states is increasing. Environmental concerns when they relate to the actions and responsibilities of states, moreover, are increasingly expressed in the language of sustainable development and the precautionary principle

    Reviews

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    Computers and Typography edited by Rosemary Sassoon, Oxford, Intellect, 1993. ISBN: 1–871516–23–4

    A Quillen model structure for Gray-categories

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    A Quillen model structure on the category Gray-Cat of Gray-categories is described, for which the weak equivalences are the triequivalences. It is shown to restrict to the full subcategory Gray-Gpd of Gray-groupoids. This is used to provide a functorial and model-theoretic proof of the unpublished theorem of Joyal and Tierney that Gray-groupoids model homotopy 3-types. The model structure on Gray-Cat is conjectured to be Quillen equivalent to a model structure on the category Tricat of tricategories and strict homomorphisms of tricategories.Comment: v2: fuller discussion of relationship with work of Berger; localizations are done directly with simplicial set
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