bluuebunny/crossref_metadata_2025 huggingface dataset:
Évaluation L.V.R. d’un document audio-scripto-visuel éducatif
Authors: Berthelot Serge , Bordeleau Pierre
Published: July 2012

Cette étude, qui s’inscrit dans le cadre des travaux du GRERDAVE*, porte sur l’un des critères qui permet de choisir des étudiants pour la mise à l’essai d’un document éducatif, en évaluation L.V.R. (« Learner Verification and Revision » : Komoski, 1974), selon le mode tutoriel. Ce critère, c’est le niveau de verbalisation de l’étudiant. Dans un premier temps, le prototype d’un diaporama destiné à des étudiants au collégial, sur l’ajustement du système de visée des carabines, a été réalisé. Celui-ci a ensuite été mis à l’essai auprès de trois étudiants de niveaux de verbalisation différents : fort, moyen, faible. Un vérificateur a alors recueilli des informations en observant et en interrogeant (mode tutoriel) les étudiants. Celles-ci ont été soumises à des réviseurs qui les ont transformées en prescriptions de révisions. Trois versions révisées du prototype ont alors été produites selon ces prescriptions. Enfin, le prototype et les trois versions révisées ont été expérimentés auprès de quatre groupes d’étudiants d’un C.E.G.E.P. de la Rive-Sud de Montréal. Nous voulions vérifier laquelle des versions révisées ou du prototype était le plus efficace par rapport à l’atteinte des objectifs par les étudiants, mesurée à l’aide d’un test critérié.

* Groupe de Recherche sur l’Évaluation et la Révision des Documents Audio-Visuels Éducatifs, Section de Technologie éducationnelle, Faculté des Sciences de l’Éducation, Université de Montréal. Les travaux du GRERDAVE ont été rendus possibles grâce à des subventions de l’Université de Montréal et du ministère de l’Éducation du Québec, programme FCAC.
Essai philosophique sur l’action : prolégomènes à l’éducation
Authors: Brassard Jean
Published: July 2012

L’homme habite un univers et l’univers ambiant imprègne l’homme. Il s’agit de l’union intime de deux dynamismes ouverts et prégants d’actualisation intégrale dans la complémentarité et la solidarité de leurs actifs.

L’homme d’action peut intervenir intelligemment dans l’évolution de l’oeuvre civilisatrice s’il affine son sens de la perspective. Il s’agira pour l’homme d’investir un effort constamment renouvelé et enrichi de synthèse, résultat d’une délibération éclairée, motivée et prudente. C’est d’une telle délibération conscientielle que pourra jaillir ce qu’il est convenu d’appeler: le zest vital.
L’évaluation de l’enseignement : recherche d’une cohérence pour le projet éducatif
Authors: Maheux Martin Jeanne
Published: July 2012

L’évaluation est certes l’un des aspects de l’enseignement qui soit le plus difficile à concrétiser. Nul ne discute la nécessité d’objectiver tout jugement sur la valeur d’un enseignement. Toutefois, l’unanimité sur les procédures d’évaluation est difficilement réalisable lorsque vient le temps de passer à l’action. La diversité des modèles d’évaluation et la prolifération des instruments contribuent à maintenir les divergences d’opinion sur « ce qui serait la meilleure façon d’évaluer! »

Cet article propose un cadre de référence pour l’action en matière d’évaluation de l’enseignement au moment où cette activité, l’enseignement, s’ouvrira aux collectivités par le biais des projets éducatifs. Ce cadre de référence est d’inspiration systémique. Tel que présenté, il permet d’articuler en une démarche cohérente quelques-uns des modèles d’évaluation contemporains. La complémentarité des modèles apparaît alors comme une caractéristique inhérente à l’évaluation de l’enseignement.
Développement vocationnel de l’adulte : nécessité de construire un modèle théorique
Authors: Riverin-Simard Danielle
Published: July 2012

Cet article traite en un premier temps de l’importance de l’étude du développement vocationnel de l’adulte dans le cadre de la problématique de l’éducation permanente. En un deuxième temps, il fait état des écrits pertinents relatifs à ce développement vocationnel de l’adulte et présente une certaine critique plus détaillée des théories ou modèles théoriques existants, afin de mieux situer la nécessité de la construction d’un nouveau modèle théorique.
Fonction rythmique et décodage phonétique en lecture chez les enfants de 7 à 12 ans
Authors: Ruel Pierre-H.
Published: July 2012

Au terme d’un article antérieur, Volume IV, numéro 2, nous formulions comme hypothèse que la fonction rythmique, en tant que telle, aurait un effet plus différentiel sur l’apprentissage des sons en lecture que l’effet observé de la fonction composite bivalente de la temporalité que nous avions alors infirmée. La présente étude entend vérifier cette hypothèse, à partir des résultats obtenus avec le même échantillon (Sherbrooke, 1973). L’étude se situe, cette fois, dans les limites d’une dynamique autonome et compare les rendements obtenus à deux épreuves, rythme et lecture, par quatre « groupes hypothétiques » caractérisés par des rendements différents.
De la crise de l’homme à la créativité
Authors: Morin Lucien
Published: July 2012

Nos soucis et nos intérêts contemporains pour le phénomène de la créativité proviennent de sources multiples. Il en est une qui, aux yeux de l’auteur de cet article, semble particulièrement révélatrice des aspirations profondes de l’homme d’aujourd’hui : elle concerne son besoin de sens et de significations ultimes. La créativité — vue ici dans une perspective « philosophique » — est soupçonnée de posséder des propriétiés essentielles dont les similitudes avec les caractéristiques d’un être en crise, d’un homme en crise, sont d’une fécondité exceptionnellement éclairante pour la compréhension de la crise de l’homme contemporain. Cet article représente le premier d’une série de trois.
Contribution à l’analyse des résultats des tests de pensée créative de E.P. Torrance par la technique de l’évaluation informative
Authors: Amégan Samuel
Published: July 2012

Depuis quelques années déjà, la recherche psychologique a révélé que la pensée créative est une réalité multiforme dont les principaux aspects cognitifs sont la fluidité, la flexibilité, l’originalité, l’élaboration et les transformations.

Une action éducative intentionnelle peut-elle influencer d’égale façon ces différents aspects? Ou bien quelques-uns de ces aspects sont-ils plus influençables que d’autres?

L’utilisation d’une technique appropriée, l’évaluation informative, s’avère une approche fructueuse pour répondre à ces questions bien plus que l’évaluation sommative classique.
Éducation technique et culture scolaire : une relation difficile. L’exemple français
Authors: Hörner Wolfgang
Published: July 2012

La polarisation de la réforme des curricula autour du problème d’une initiation au monde du travail fait apparaître le problème général de la relation entre l’école et son environnement socio-économique. En analysant l’évolution de l’éducation technique en France depuis presque 20 ans l’article montre comment l’école se sert des nouveaux éléments venus de son environnement socio-économique non pas pour s’ouvrir au monde extérieur, mais pour régler ses conflits internes. Les revendications de la société semblent passer par le tamis de l’autonomie relative du système éducatif qui essaie d’adapter tout contenu nouveau à sa conception traditionnelle de la culture générale, sans se soucier du problème pédagogique primordial que constitue la motivation des élèves, déterminée précisément par des facteurs de l’environnement socio-économique.
Choix « moral » et niveau scolaire
Authors: Bajard Guy
Published: July 2012

Nous avons cherché à vérifier l’hypothèse de l’évolution du jugement moral posée par Piaget et précisée par Kohlberg. Deux épreuves, à notation objective, fondées sur la description que Getzels et Jackson ont fait de la personne « morale » ont été administrées à cinq échantillons d’élèves normalement scolarisés du C.M.2 en 3ème (40 G et 40 F par niveau). L’analyse de variance à deux facteurs de classification (Sexe x Âge scolaire) vérifie effectivement l’évolution attendue mais pour une épreuve seulement : « opinion personnelle ». En outre, à tous les niveaux scolaires envisagés le choix de l’alternative morale est significativement plus fréquent chez les filles que chez les garçons. L’examen des corrélations révèle que : a) les résultats aux deux épreuves expérimentales sont indépendants des aptitudes intellectuelles des sujets et également, b) indépendants des résultats scolaires.
La généralisabilité des seuils de performance établis par des appréciateurs : étude de trois procédés
Authors: Scallon Gérard
Published: July 2012

Cette recherche avait pour but de comparer trois procédés faisant appel à des appréciateurs pour déterminer le seuil de performance à un examen de dix questions : les procédés d’Angoff, d’Ebel et de Nedelsky. D’après les résultats de l’analyse de la variance, les seuils obtenus ne sont pas comparables d’un procédé à l’autre ni d’un appréciateur à l’autre. Toutefois, la concordance entre les appréciateurs est apparue la plus élevée dans le cas du procédé de Nedelsky. De plus, d’après l’étude de généralisabilité, la différenciation entre les questions s’est avérée fiable et ce, quels que soient les appréciateurs et les procédés. Bien que cette recherche ait mis en évidence la subjectivité qui caractérise la détermination d’un seuil de performance par des appréciateurs, les résultats obtenus suggèrent des avenues à explorer, tant du côté de l’analyse des questions d’un examen que du côté de la notion de compétence minimale.
Problèmes à surmonter dans l’intégration scolaire
Authors: Robichaud Omer , Landry Rodrigue
Published: July 2012

Cet article fournit une synthèse des problèmes les plus importants à surmonter pour assurer la réussite du mouvement d’intégration, dans les classes régulières, des enfants qui ont des besoins spéciaux. Les problèmes sont analysés à partir des composantes essentielles d’un modèle d’enseignement individualisé, soit : l’enfant, le processus d’instruction et les agents éducatifs. Il n’apparaît pas souhaitable d’entreprendre toute intégration avant que les enseignants aient les ressources et les habiletés nécessaires à l’enseignement individualisé.
La crise d’identité de l’adulte et ses incidences éducatives
Authors: Artaud Gérard
Published: July 2012

Le but du présent article est d’analyser l’impact de la crise d’identité de l’adulte sur la relation éducative. Partant des conclusions convergentes de plusieurs recherches sur l’adulte, on propose une hypothèse explicative de sa crise de croissance qui permet de mettre en lumière le caractère défensif de certains de ses comportements et de montrer comment le fait d’amorcer un processus de réconciliation avec lui-même modifie son attitude envers l’enfant.
Les comportements mathématiques des jeunes enfants en tant que produits d’un système de traitement de l’information et reflets de méthodes d’apprentissage
Authors: Lemoyne Gisèle
Published: July 2012

L’étude présente analyse, en termes de traitement de l’information, certains comportements d’élèves de première année face à des tâches simples d’addition et de soustraction, ainsi qu’à des exercices de complétion de suites numériques. Elle montre aussi comment ces comportements peuvent être améliorés à la suite d’interventions sur les processus de mémoire à court terme et sur l’intégration des connaissances en mémoire à long terme.
L’analyse des besoins d’apprentissage
Authors: Lapointe Jacques
Published: July 2012

Dans cet article, l’auteur présente des arguments démontrant l’utilité d’analyser les besoins d’apprentissage ainsi que la nécessité d’intégrer cette pratique dans le développement systématique des systèmes d’enseignement. Il développe son argumentation selon les thèmes suivants : les finalités déclarées et les finalités poursuivies; la fidélité, la validité et l’utilité des finalités visées; l’incongruence des finalités par rapport aux divers niveaux de décision du système éducatif; l’expression vague des finalités poursuivies; la diversité des finalités souhaitées selon la nature des groupes consultés; la mesurabilité, critère trop souvent utilisé seul dans le choix des objectifs; la confusion entre les fins et les moyens.
L’approche qualitative et l’approche quantitative dans les recherches en éducation
Authors: Poisson Yves
Published: July 2012

Bien des chercheurs en éducation ont été portés à soutenir et à professer que seule l’approche quantitative pouvait présenter assez de garanties pour faire d’une recherche en éducation une recherche sérieuse et fiable. L’auteur, après avoir résumé ce qu’il entend par approche quantitative et approche qualitative, analyse les circonstances qui ont conduit à un changement de paradigme dans les sciences de l’éducation; il en vient à la conclusion qu’un nouveau paradigme est peut-être en voie d’apparaître.
Pour une approche fonctionnelle de l’intégration des matières au primaire
Authors: Boyer Jean-Yves
Published: July 2012

L’intégration des matières connaît présentement un regain de faveur dans le débat pédagogique québécois. En vue de contribuer à une mise à jour de cette problématique, l’auteur esquisse un aperçu historique de la question, puis propose une mise au point terminologique. La suite de l’article décrit les composantes d’un modèle d’intégration qualifié de fonctionnel. Ce modèle, par opposition à l’approche thématique, prétend tenir compte à la fois du vécu de l’élève, de la spécificité des programmes et de l’ensemble de la réalité scolaire actuelle.
Manifolds: a global setting for geometry and analysis, with or without coordinates
Authors: Goldman William M.
Published: July 2012

Manifolds are curved spaces that admit local coordinate systems which look like Euclidean space. Much of the classical geometry of Euclidean space extends and generalizes to manifolds. A generalization of Euclidean geometry is Riemannian geometry, where distances are defined which, in small regions, look like Euclidean geometry. This article describes how familiar concepts of Euclidean geometry generalize to the context of Riemannian manifolds, as well as more general structures. WIREs Comput Stat 2012 doi: 10.1002/wics.1220

This article is categorized under:

Statistical and Graphical Methods of Data Analysis > Dimension Reduction
Drift wave instability in a radially bounded dusty magnetoplasma with parallel ion velocity shear
Authors: SHUKLA P. K. , ROSENBERG M.
Published: July 2012

Properties of the coupled dust ion-acoustic drift wave instability in a radially bounded dusty magnetoplasma with an equilibrium sheared parallel ion (SPI) flow are investigated. By using the two-fluid model for the electrons and ions, a wave equation for the low-frequency coupled dust ion-acoustic drift waves in a bounded plasma with stationary charged dust grains is derived. The wave equation admits a linear dispersion relation, which exhibits that the radial boundary affects the growth rate of the coupled ion-acoustic drift wave instability which is excited by the SPI flow. The results should be relevant to dusty magnetoplasma experiments with an SPI flow.
Hydromagnetic waves and current relaxation: Damping at short wavelengths and small conductivity
Authors: SILVEIRA FRANCISCO E.M.
Published: July 2012

Inertial and diffusive effects on the propagation of hydromagnetic waves in plasmas of finite conductivity are explored by assuming a finite relaxation time for the current density. The domain of validity of the hydromagnetic approximation is determined by defining a lower limit for the perturbative wavelength. Three independent dispersion relations are obtained. At short wavelengths, it is found that the longitudinal component of the perturbative magnetic field damps out at a finite rate, which is determined fully by the relaxation time of the current density. In the same limit, it is shown that Alfvén waves can propagate through conductive plasmas with a null group speed. It is also shown that strong inertial and diffusive effects on magnetosonic waves can be discussed by defining suitably a perturbative parameter with the dimension of speed. It is argued that relevant corrections to space and time scales describing the reconnection of magnetic field lines are expected by applying the results presented here at sufficiently high frequencies.
THE PROGRESSIVE ERA ASSAULT ON INDIVIDUALISM AND PROPERTY RIGHTS
Authors: Ely James W.
Published: July 2012

This essay examines the far-reaching attack on individualism and property rights which characterized the Progressive Era of the early twentieth century. Scholars and political figures associated with Progressivism criticized the individualist values of classical liberalism and rejected the traditional notion of limited government espoused by the framers of the Constitution. They expressed great confidence in regulatory agencies, staffed by experts, to effectuate policy. Progressives paved the way for the later triumph of statist ideology with the New Deal in the 1930s.

The essay traces the sources of the Progressive antipathy to individual rights to the influence of Bismarck’s program in Imperial Germany and the Social Gospel theology. It gives attention to the views of leading Progressive intellectuals who stressed the perceived need for increased governmental power and governance by an educated elite. The essay also explores the impact of Progressivism on constitutional law, arguing that the rise of “sociological jurisprudence,” with its skepticism about courts and stress on judicial deference to legislative judgments, served to advance the Progressive political agenda. Progressives looked with disfavor on any constitutional doctrine which curtailed governmental authority. The Progressive movement left a lasting legacy of diminished regard for individualism and a jurisprudence which stripped property of muscular constitutional protection.
LYSANDER SPOONER: NINETEENTH-CENTURY AMERICA'S LAST NATURAL RIGHTS THEORIST
Authors: Mack Eric
Published: July 2012

The main purpose of this essay is to articulate the ideas of the last powerful advocate of natural rights in nineteenth-century America. That last powerful advocate was the Massachusetts-born radical libertarian Lysander Spooner (1808-1887). Besides his powerful antebellum attacks on slavery, Spooner developed forceful arguments on behalf of a strongly individualistic conception of natural law and private property rights and against coercive moralism, coercive paternalism, and state authority and legislation. This essay focuses on the theoretical core of Spooner’s position which is his doctrine of natural rights—a doctrine that is primarily developed in Spooner’sThe Law of Intellectual Property(1855),Natural Law(1882), andA Letter to Grover Cleveland(1886). I situate Spooner within the libertarian tradition in political thought by beginning this essay with an examination of two English writers whose radical writings (for the most part) preceded Spooner’s—Thomas Hodgskin (1787-1869) and the early Herbert Spencer (1820-1903). I emphasis the strongly Lockean character of Spooner’s thought and support this contention in part by showing how much more Lockean Spooner was than either Hodgskin or the early Spencer.
THE IDEA OF RIGHTS IN THE IMPERIAL CRISIS
Authors: Yirush Craig
Published: July 2012

This essay examines the idea of rights advanced by the American colonists in the imperial crisis (1763-1776). It argues that the colonists viewed all English subjects as having the same fundamental rights as individuals everywhere in the empire. These individual rights (to life, liberty, and property) were in turn guaranteed by the right to consent to taxation. In the empire, the colonists insisted, these rights could only be protected by the colonial legislatures as they were not represented in the British Parliament, which in turn meant that the colonies must have the ability to govern themselves in all internal matters, a claim which ultimately led to the idea of each colony as a “free state,” independent of King and Parliament. While the colonists began by defending these rights on the basis of their legal inheritance as Englishmen, they gradually moved towards a more radical claim: that these rights were theirs based on the law of nature, and thus open to all men in principle. This move to natural rights was based in part on the colonial claim that they had migrated to America, a place inhabited by indigenous peoples whom they viewed as “savages” and thus outside of the jurisdiction of the English common law. The radical move to natural rights, however, was in tension with the loose confederation which emerged in the years after 1776 in which each colony was now a quasi-independent republican state and in which the rights of minorities—Native Americans, African Americans, religious dissenters, and Loyalists—could not be effectively protected by the federal government.
ON DECLARING THE LAWS AND RIGHTS OF NATURE
Authors: Thompson C. Bradley
Published: July 2012

This article examines the moral theory of the American Revolutionary and Founding periods by focusing on two key concepts of that doctrine: the moral laws and the moral rights of nature. In particular, the article will examine several important questions from the perspective of America’s Revolutionary generation: What are the moral laws and rights of nature? What is the difference between a law and a right of nature, and how are the laws and rights of nature related to each other? Are nature’s moral laws and rights descriptive, prescriptive, or both? What are the attributes and sanctions of nature’s laws and rights, and how are they promulgated? What is the source of nature’s laws and rights? And finally, how did America’s founding fathers use the laws and rights of nature to establish their political institutions? In order to answer these questions, the article focuses on the core text universally recognized as the symbol of America’s revolutionary mind and moral theory: the Declaration of Independence. The Declaration’s deepest philosophic meaning is herein illuminated by also examining the broader, extant literature of the period.
Orating Verdi: Death and the mediac.1901
Authors: WILLIAMS GAVIN
Published: July 2012

This article explores Verdi's death as a ‘media event’, tracing the unfolding news from the earliest reports of his imminent demise up to the monumental commemorations held 30 days afterwards. Throughout this time, news media helped to define a period of so-called national mourning. Yet a broader range of media (including the telegraph, tram and railway) played an important role in demarcating the geopolitical scope of this collective grief. As a point of comparison, Verdi's death is considered in relation to the assassination of King Umberto I – a recent incident, of greater magnitude, which had provoked a spell of national mourning only months into the new century. Echoes of Umberto's assassination can be heard in responses to Verdi's death, linking both events to a common historical and political moment. This new context for understanding Verdi's final moments not only seeks to illuminate the manifold interactions between public and persona in Liberal Italy but also raises questions about the construction of auditory experiences in national mourning and the sensory dimension of the nation state's lugubrious politics.
Adapting to Unavoidable Loss During Adulthood
Authors: John Dennis , Lang Frieder R.
Published: July 2012

Older adults are expected to better differentiate functional from dysfunctional ways of dealing with unavoidable loss. We examined whether age-differential effects of strategies on affect could be found in a simulation task concerning unavoidable loss management. In an experimental study, we confronted 83 healthy young, middle-aged, and old adults with video vignettes of a person suffering from multiple sclerosis. Participants engaged in a thinking-aloud task on managing their life after learning about the fictitious diagnosis. Only the older participants’ striving for improvement was associated with an increase in negative affect after the thinking-aloud task, whereas their reorientation strategies led to enhanced affective well-being. Findings revealed age-differential effects of mentally simulating unavoidable loss.
ECE-imaging of the H-mode pedestal (invited)
Authors: Tobias B. J. , Austin M. E. , Boom J. E. , Burrell K. H. , Classen I. G. J. , Domier C. W. , Luhmann N. C. , Nazikian R. , Snyder P. B.
Published: July 2012

A synthetic diagnostic has been developed that reproduces the highly structured electron cyclotron emission (ECE) spectrum radiated from the edge region of H-mode discharges. The modeled dependence on local perturbations of the equilibrium plasma pressure allows for interpretation of ECE data for diagnosis of local quantities. Forward modeling of the diagnostic response in this region allows for improved mapping of the observed fluctuations to flux surfaces within the plasma, allowing for the poloidal mode number of coherent structures to be resolved. In addition, other spectral features that are dependent on both Te and ne contain information about pedestal structure and the electron energy distribution of localized phenomena, such as edge filaments arising during edge-localized mode (ELM) activity.
Computer simulations of nematic drops: Coupling between drop shape and nematic order
Authors: Rull L. F. , Romero-Enrique J. M. , Fernandez-Nieves A.
Published: July 2012

We perform Monte Carlo computer simulations of nematic drops in equilibrium with their vapor using a Gay-Berne interaction between the rod-like molecules. To generate the drops, we initially perform NPT simulations close to the nematic-vapor coexistence region, allow the system to equilibrate and subsequently induce a sudden volume expansion, followed with NVT simulations. The resultant drops coexist with their vapor and are generally not spherical but elongated, have the rod-like particles tangentially aligned at the surface and an overall nematic orientation along the main axis of the drop. We find that the drop eccentricity increases with increasing molecular elongation, κ. For small κ the nematic texture in the drop is bipolar with two surface defects, or boojums, maximizing their distance along this same axis. For sufficiently high κ, the shape of the drop becomes singular in the vicinity of the defects, and there is a crossover to an almost homogeneous texture; this reflects a transition from a spheroidal to a spindle-like drop.
Theory of the forced wetting transition
Authors: Chan Tak Shing , Snoeijer Jacco H. , Eggers Jens
Published: July 2012

We consider a solid plate being withdrawn from a bath of liquid which it does not wet. At low speeds, the meniscus rises below a moving contact line, leaving the rest of the plate dry. At a critical speed of withdrawal, this solution bifurcates into another branch via a saddle-node bifurcation: two branches exist below the critical speed, the lower branch is stable, the upper branch is unstable. The upper branch eventually leads to a solution corresponding to film deposition. We add the local analysis of the upper branch of the bifurcation to a previous analysis of the lower branch. We thus provide a complete description of the dynamical wetting transition in terms of matched asymptotic expansions.
Nanosize icosahedral quasicrystal in Mg90Ca10 glass: An ab initio molecular dynamics study
Authors: Durandurdu Murat
Published: July 2012

Rapid solidification of Mg90Ca10 from its liquid state is studied by means of an ab initio molecular dynamics technique, and its local structure is investigated by various analyzing methods. The liquid and amorphous states are found to have slightly different short range order even though the perfect and defective icosahedral bonding environments are major bonding elements of both liquid and amorphous states. Perfect icosahedrons with a small frequency exist in the liquid state, more develop during the cooling process and they become the leading building units in the glass state, indicating an icosahedral short range order in Mg90Ca10 glass. Also the linked icosahedrons lead to an icosahedral medium range order. Furthermore, an ordered arrangement of some icosahedrons in the hexagonal symmetry is observed in the glass model, representing a nanoscale icosahedral quasicrystalline phase in Mg90Ca10 glass.
Kelvin-Helmholtz instability in a strongly coupled dusty plasma medium
Authors: Tiwari Sanat Kumar , Das Amita , Angom Dilip , Patel Bhavesh G. , Kaw Predhiman
Published: July 2012

The Kelvin-Helmholtz (KH) instability in the context of strongly coupled dusty plasma medium has been investigated. In particular, the role of transverse shear and the compressional acoustic modes in both the linear and nonlinear regimes of the KH instability has been studied. It is observed that in addition to the conventional nonlocal KH instability, there exists a local instability in the strong coupling case. The interplay of the KH mode with this local instability shows up in the simulations as an interesting phenomenon of recurrence in the nonlinear regime. Thus, a cyclic KH instability process is observed to occur. These cyclic events are associated with bursts of activity in terms of transverse and compressional wave generation in the medium.
Role of the laser pulse-length in producing high-quality electron beams in a homogenous plasma
Authors: Upadhyay Ajay K. , Arun Samant Sushil , Krishnagopal Srinivas
Published: July 2012

In laser wakefield acceleration, the pulse-length of the laser is an important parameter that affects the laser evolution and electron beam injection and acceleration in the bubble regime. Here, we use three-dimensional simulations to find, for a given plasma density, the optimal pulse-length that gives the best quality electron beam. For three different pulse lengths, we study the evolution dynamics of the laser spot-size and quality of the injected electron beam. We find that a pulse-length that is less than the theoretical optimum, τL = λp/√2πc, derived from linear theory, gives the best beam quality. Conversely, our simulations suggest that for a given laser system, with a fixed pulse-length, there is an optimal value of the plasma density that will give the best quality accelerated beams in experiments. For an rms pulse-length of 10 fs (around 24 fs FWHM), this corresponds to a plasma density of around 3.4 × 1018/cm3. For these parameters, we obtain, in a homogenous plasma and with a single laser, an electron beam with an energy of around 700 MeV, an energy-spread less than 2%, and rms normalized emittance of a few π mm-mrad.
An inside-out Eaton lens made of H-fractal metamaterials
Authors: Wu Qiannan , Feng Xiaoyi , Chen Ruirui , Gu Chendong , Li Sucheng , Li Hui , Xu Yadong , Lai Yun , Hou Bo , Chen Huanyang , Li Yunhui
Published: July 2012

We report an experiment on an inside-out Eaton lens fabricated using H-fractal metamaterials, copper printed on printed circuit boards in H-fractal patterns. The lens can perform good imaging functionality with both sources and images inside the vacuum core. The H-fractal metamaterials also provide design technique to achieve refractive index ranging in [0,1] with little loss in microwave spectrum. Excellent agreements between numerical and experimental results have been demonstrated.
Controllable threshold voltage shifts of polymer transistors and inverters by utilizing gold nanoparticles
Authors: Han Su-Ting , Zhou Ye , Xu Zong-Xiang , Roy V. A. L.
Published: July 2012

We have demonstrated controllable threshold voltage (Vth) shifts of gold nanoparticles (Au NPs)/poly (3-hexylthiophene) (P3HT) based composite transistors that are fabricated through a low temperature facile technique. By varying the doping concentration of gold nanoparticles in P3HT matrix, Vth has been tuned from 12 V to 27 V without device degradation. Using this technique, the switching voltages of unipolar inverters have also been systematically tuned. Efficient hole conduction and a variation in P3HT crystallinity was observed due to different concentrations of Au NPs which eventually shift the threshold voltage of the devices in a controlled manner.
Rectification of evanescent heat transfer between dielectric-coated and uncoated silicon carbide plates
Authors: Iizuka Hideo , Fan Shanhui
Published: July 2012

Here, we show analytically that the thermal rectification via evanescent waves is obtained in the parallel semi-infinite bodies of the dielectric-coated silicon carbide and uncoated silicon carbide. The permittivity and the thickness of the dielectric coating are derived for maximizing the thermal rectification. In the nonequilibrium situation holding temperatures of 500 K for one body and 300 K for the other, either a coating with a high permittivity of 14 and a thickness of 1 nm or a coating with a low permittivity of 2 and a thickness exceeding 10 nm, results in rectifying coefficients of 0.4 to 0.44.
Influence of surface topology on the electrical response of many bead assemblies
Authors: Tekaya A. , Bouzerar R. , Bourny V.
Published: July 2012

We propose an interpretation of the voltage creep observed in metallic grain assemblies based on the sensitivity of the electrical properties to the surface topology of the beads. From the real area of contact between adjacent beads, directly measured through the bulk resistance of a single bead, we derive a simple relation between the voltage creep rate and the creep rate of the interface friction coefficient, regarded as an aging process expressing asperity creep. The likely influence of the Branly effect on the aging process is briefly discussed.
Honeycomb Films from Perfluoropolyether-Based Star and Micelle Architectures
Authors: Zhang Zhou , Hao Xiaojuan , Gurr Paul A. , Blencowe Anton , Hughes Timothy C. , Qiao Greg G.
Published: July 2012

A perfluoropolyether-b-poly(t-butyl acrylate) (PFPE-b-PtBA) block copolymer macroinitiator was used to prepare both core cross-linked star (CCS) polymers and micelles, whereby the outer shell and core, respectively, are comprised of fluorinated segments. The star polymer complete with PFPE outer shell was synthesised via atom transfer radical polymerisation (ATRP) and the arm-first approach, through cross-linking of the PFPE-b-PtBA macroinitiator with ethylene glycol diacrylate (EGDA). Alternatively, the PFPE-b-PtBA block copolymer could be self-assembled in benzene to form micelles with a PtBA shell and PFPE core. Both the micelle and CCS polymer were subsequently fabricated into non-cracking honeycomb (HC) patterned films on both planar and non-planar surfaces via the ‘Breath Figure’ (BF) technique using a static casting system.
The rat oocyte synthesises melatonin
Authors: Sakaguchi Kenichiro , Itoh Masanori T. , Takahashi Noriyuki , Tarumi Wataru , Ishizuka Bunpei
Published: July 2012

Melatonin (N-acetyl-5-methoxytryptamine) is an indoleamine originally identified in the pineal gland, where it is synthesised enzymatically from serotonin (5-hydroxytryptamine) by the sequential action of arylalkylamine N-acetyltransferase (AANAT) and acetylserotonin O-methyltransferase (ASMT; also known as hydroxyindole O-methyltransferase). Melatonin directly affects ovarian functions and previous studies have suggested that melatonin is synthesised in the ovary. In the present study, we examined whether AANAT and ASMT are expressed in the adult rat ovary. Reverse transcription–polymerase chain reaction analyses demonstrated that both AANAT and ASMT mRNAs are expressed in the ovary. Western blotting for AANAT protein showed that the ovary, like the pineal gland, contains this enzymatic protein with a molecular mass of 24 kDa. Immunohistochemistry revealed that the AANAT protein is localised to the oocyte, corpus luteum and medulla, including mast cells. AANAT protein was found in oocytes at all stages of follicular development, and its levels in oocytes increased progressively throughout follicular development. Furthermore, isolated oocytes metabolised exogenous serotonin to melatonin. These findings demonstrate that melatonin is synthesised from serotonin in oocytes. Melatonin synthesised in the oocyte may be implicated in its own growth or maturation, for example, by acting as a calmodulin antagonist or an antioxidant.
Peripheral inflammatory disease associated with centrally activated IL-1 system in humans and mice
Authors: Lampa Jon , Westman Marie , Kadetoff Diana , Agréus Anna Nordenstedt , Le Maître Erwan , Gillis-Haegerstrand Caroline , Andersson Magnus , Khademi Mohsen , Corr Maripat , Christianson Christina A. , Delaney Ada , Yaksh Tony L. , Kosek Eva , Svensson Camilla I.
Published: July 2012

During peripheral immune activation caused by an infection or an inflammatory condition, the innate immune response signals to the brain and causes an up-regulation of central nervous system (CNS) cytokine production. Central actions of proinflammatory cytokines, in particular IL-1β, are pivotal for the induction of fever and fatigue. In the present study, the influence of peripheral chronic joint inflammatory disease in rheumatoid arthritis (RA) on CNS inflammation was investigated. Intrathecal interleukin (IL)-1β concentrations were markedly elevated in RA patients compared with controls or with patients with multiple sclerosis. Conversely, the anti-inflammatory IL-1 receptor antagonist and IL-4 were decreased in RA cerebrospinal fluid (CSF). Tumor necrosis factor and IL-6 levels in the CSF did not differ between patients and controls. Concerning IL-1β, CSF concentrations in RA patients were higher than in serum, indicating local production in the CNS, and there was a positive correlation between CSF IL-1β and fatigue assessments. Next, spinal inflammation in experimental arthritis was investigated. A marked increase of IL-1β, IL-18, and tumor necrosis factor, but not IL-6 mRNA production, in the spinal cord was observed, coinciding with increased arthritis scores in the KBxN serum transfer model. These data provide evidence that peripheral inflammation such as arthritis is associated with an immunological activation in the CNS in both humans and mice, suggesting a possible therapeutic target for centrally affecting conditions as fatigue in chronic inflammatory diseases, for which to date there are no specific treatments.
Point process modelling of the Afghan War Diary
Authors: Zammit-Mangion Andrew , Dewar Michael , Kadirkamanathan Visakan , Sanguinetti Guido
Published: July 2012

Modern conflicts are characterized by an ever increasing use of information and sensing technology, resulting in vast amounts of high resolution data. Modelling and prediction of conflict, however, remain challenging tasks due to the heterogeneous and dynamic nature of the data typically available. Here we propose the use of dynamic spatiotemporal modelling tools for the identification of complex underlying processes in conflict, such as diffusion, relocation, heterogeneous escalation, and volatility. Using ideas from statistics, signal processing, and ecology, we provide a predictive framework able to assimilate data and give confidence estimates on the predictions. We demonstrate our methods on the WikiLeaks Afghan War Diary. Our results show that the approach allows deeper insights into conflict dynamics and allows a strikingly statistically accurate forward prediction of armed opposition group activity in 2010, based solely on data from previous years.
E-cadherin is under constitutive actomyosin-generated tension that is increased at cell–cell contacts upon externally applied stretch
Authors: Borghi Nicolas , Sorokina Maria , Shcherbakova Olga G. , Weis William I. , Pruitt Beth L. , Nelson W. James , Dunn Alexander R.
Published: July 2012

Classical cadherins are transmembrane proteins at the core of intercellular adhesion complexes in cohesive metazoan tissues. The extracellular domain of classical cadherins forms intercellular bonds with cadherins on neighboring cells, whereas the cytoplasmic domain recruits catenins, which in turn associate with additional cytoskeleton binding and regulatory proteins. Cadherin/catenin complexes are hypothesized to play a role in the transduction of mechanical forces that shape cells and tissues during development, regeneration, and disease. Whether mechanical forces are transduced directly through cadherins is unknown. To address this question, we used a Förster resonance energy transfer (FRET)-based molecular tension sensor to test the origin and magnitude of tensile forces transmitted through the cytoplasmic domain of E-cadherin in epithelial cells. We show that the actomyosin cytoskeleton exerts pN-tensile force on E-cadherin, and that this tension requires the catenin-binding domain of E-cadherin and αE-catenin. Surprisingly, the actomyosin cytoskeleton constitutively exerts tension on E-cadherin at the plasma membrane regardless of whether or not E-cadherin is recruited to cell–cell contacts, although tension is further increased at cell–cell contacts when adhering cells are stretched. Our findings thus point to a constitutive role of E-cadherin in transducing mechanical forces between the actomyosin cytoskeleton and the plasma membrane, not only at cell–cell junctions but throughout the cell surface.
Gap 1 phase length and mouse embryonic stem cell self-renewal
Authors: Li Victor C. , Ballabeni Andrea , Kirschner Marc W.
Published: July 2012

In somatic cells, the length of the G1 phase of the cell cycle is tightly linked to differentiation, and its elongation can drive differentiation in many cases. Although it has been suggested that the situation is very similar in embryonic stem cells (ESCs), where a rapid cell cycle and a short G1 phase maintain the pluripotent state, evidence has been contradictory. Here we show that, in murine ESCs, elongation of the cell cycle and elongation of G1 are compatible with their pluripotent state. Multiple methods that lengthen the cell cycle and that target cyclin-dependent kinase, retinoblastoma protein, and E2F activity all fail to induce differentiation on their own or even to facilitate differentiation. The resistance of murine ESCs to differentiation induced by lengthening G1 and/or the cell cycle could allow for separate control of these events and provide new opportunities for investigation and application.
Human-like brain hemispheric dominance in birdsong learning
Authors: Moorman Sanne , Gobes Sharon M. H. , Kuijpers Maaike , Kerkhofs Amber , Zandbergen Matthijs A. , Bolhuis Johan J.
Published: July 2012

Unlike nonhuman primates, songbirds learn to vocalize very much like human infants acquire spoken language. In humans, Broca’s area in the frontal lobe and Wernicke’s area in the temporal lobe are crucially involved in speech production and perception, respectively. Songbirds have analogous brain regions that show a similar neural dissociation between vocal production and auditory perception and memory. In both humans and songbirds, there is evidence for lateralization of neural responsiveness in these brain regions. Human infants already show left-sided dominance in their brain activation when exposed to speech. Moreover, a memory-specific left-sided dominance in Wernicke’s area for speech perception has been demonstrated in 2.5-mo-old babies. It is possible that auditory-vocal learning is associated with hemispheric dominance and that this association arose in songbirds and humans through convergent evolution. Therefore, we investigated whether there is similar song memory-related lateralization in the songbird brain. We exposed male zebra finches to tutor or unfamiliar song. We found left-sided dominance of neuronal activation in a Broca-like brain region (HVC, a letter-based name) of juvenile and adult zebra finch males, independent of the song stimulus presented. In addition, juvenile males showed left-sided dominance for tutor song but not for unfamiliar song in a Wernicke-like brain region (the caudomedial nidopallium). Thus, left-sided dominance in the caudomedial nidopallium was specific for the song-learning phase and was memory-related. These findings demonstrate a remarkable neural parallel between birdsong and human spoken language, and they have important consequences for our understanding of the evolution of auditory-vocal learning and its neural mechanisms.
Monitoring cotranslational protein folding in mammalian cells at codon resolution
Authors: Han Yan , David Alexandre , Liu Botao , Magadán Javier G. , Bennink Jack R. , Yewdell Jonathan W. , Qian Shu-Bing
Published: July 2012

How the ribosome-bound nascent chain folds to assume its functional tertiary structure remains a central puzzle in biology. In contrast to refolding of a denatured protein, cotranslational folding is complicated by the vectorial nature of nascent chains, the frequent ribosome pausing, and the cellular crowdedness. Here, we present a strategy called folding-associated cotranslational sequencing that enables monitoring of the folding competency of nascent chains during elongation at codon resolution. By using an engineered multidomain fusion protein, we demonstrate an efficient cotranslational folding immediately after the emergence of the full domain sequence. We also apply folding-associated cotranslational sequencing to track cotranslational folding of hemagglutinin in influenza A virus-infected cells. In contrast to sequential formation of distinct epitopes, the receptor binding domain of hemagglutinin follows a global folding route by displaying two epitopes simultaneously when the full sequence is available. Our results provide direct evidence of domain-wise global folding that occurs cotranslationally in mammalian cells.
Emerging Issues and Methodological Advances in Fisheries Reproductive Biology
Authors: Lowerre-Barbieri Susan K. , Brown-Peterson Nancy J. , Murua Hilario , Tomkiewicz Jonna , Wyanski David M. , Saborido-Rey Fran
Published: July 2012

Although incorporating detailed reproductive data into all stock assessments is not a practical goal, the need to understand how reproductive biology affects population productivity is being increasingly recognized. More research focused on reproductive biology—coupled with a shift towards a resilience perspective in fisheries science—is resulting in challenges to many long-held assumptions; the emergence of important new issues; and identification of the need to improve data and methods used in reproductive studies. Typically, data for reproductive studies are based on an assessment of gonadal development, which is most accurately evaluated with histology. This special section of Marine and Coastal Fisheries contains contributions from a workshop on the gonadal histology of fishes that was held in Cadiz, Spain, during June 2009. These papers cover a wide range of species and reproductive topics while introducing improved and new histological techniques. In this introduction, we address the following needs: (1) to employ standardization, thereby improving our ability to conduct comparative studies; (2) to better understand patterns of gonadal development and spawning events over time; and (3) to move beyond the spawning stock biomass paradigm. We identify the contributions of special section papers to these topics and conclude by suggesting needs for future research and integration of reproductive data into both conceptual and quantitative models to better understand how reproductive performance affects population dynamics.