470 research outputs found
Neocortical spike timing-dependent depression requires astrocyte mediated retrograde signaling
No full textMechanisms underlying the induction and expression of spike-timing dependent depression at L4-L2/3 synapses in barrel cortex
Get PDFPersona?based development of a new discovery system using MERESCO open?source components
No full textSophie and Rogier are students at Delft University of Technology. Sophie is a master student of Architecture. She searches for information mostly to get inspired. Sometimes she’s looking for a specific book and uses Amazon first, because she knows what the cover looks like, but can’t remember the author or title. Rogier is writing his master’s thesis at the faculty of Civil Engineering. He searches the library for relevant publications. He is very insecure about the search results he’s getting back from the library catalogue and various bibliographic databases. Did he get the key publications? TU Delft Library’s websites and databases are not supporting either Sophie or Rogier’s needs. Sophie and Rogier are fictional customers of TU Delft Library. They are personas constructed from a context mapping study. Six different personas give our customers voices and faces. They help us specify the services and systems that our customers expect now and in the future, such as Discover (http://discover.tudelft.nl) which will replace the traditional WebOPAC. With Discover, Sophie and Rogier can use Google-like queries and drilldown facets to find both books from the catalogue and full text articles (from Elsevier, DOAJ, Repositories and more). Records are enriched with cover images, abstracts, user ratings and LibraryThing tags. Discover is built with Meresco open source component library, which uses the Lucene search engine.Library TU DelftDelft University of Technolog
Author Correction: Toddlers strategically adapt their information search
No full textCorrection to: Nature Communicationshttps://doi.org/10.1038/s41467-024-48855-4, published online 10 July 2024 In this article the affiliation ‘Max Planck Research Group iSearch, Max Planck Institute for Human Development, Berlin, Germany’ was incorrectly given for Rogier Mars but should have been removed. In addition, the affiliation ‘Wellcome Centre for Integrative Neuroimaging, Centre for Functional MRI of the Brain (FMRIB), Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, University of Oxford, Oxford, UK’ was incorrectly given for Azzurra Ruggeri but should have been ‘Max Planck Research Group iSearch, Max Planck Institute for Human Development, Berlin, Germany’. The original article has been corrected
Le Peire Rogier de Peire d’Alvernhe revisité par l’auteur de Flamenca : Guillem de Nevers, le troubadour au psautier
No full textS’il a été établi que les paroles constitutives du dialogue amoureux entre les personnages du roman, Guillem de Nevers et Flamenca, prenaient leur source dans les vers de Peire Rogier (Ges non puesc en bon vers fallir, sixième cobla) ou encore dans ceux, inspirés du précédent, de Guiraut de Borneil (̶ Ai las, com mor ! – Quez as, amis ?), le lien entre Guillem de Nevers et Peire Rogier apparaît davantage évident si l’on prend en compte la vida de ce dernier ainsi que la cobla que lui consacre Peire d’Alvernhe dans sa chanson satirique Cantarai d’aqestz trobadors. Dans cette chanson, une partie du conseil de Peire d’Alvernhe à Peire Rogier – à savoir qu’au lieu de chanter l’amour devant tous, il devrait tenir un psautier à l’église ̶ resserre d’autant plus les liens entre le troubadour et le personnage du roman. Il semble que l’auteur de Flamenca se soit amusé à fondre dans son personnage le troubadour Peire Rogier afin de lui faire suivre les conseils de Peire d’Alvernhe mais en redirigeant la satire – qui visait le troubadour dans la chanson ̶ , vers la société religieuse et, en apparence, courtoise de son roman : il instaure un jeu particulièrement ingénieux autour de la symbolique du psautier et de celle de l’homme religieux. En effet, l’auteur s’amuse à faire de Guillem un clerc dont l’ordination n’a pas d’autre raison que l’amour qu’il éprouve pour Flamenca comme il s’amuse à faire du livre sacré le support où Guillem lit – par le biais de la bibliomancie – l’avenir de son amour avec Flamenca, le support par lequel les baisers de paix préfigurent les baisers amoureux, le support au-dessus duquel il échange les mots d’amour avec Flamenca. L’auteur s’ingénie ainsi à recouvrir les mots et les gestes sacrés par les mots et les gestes de la fin’amor afin de nous laisser entendre que le sacré est à trouver dans les valeurs de cette dernière qui elles-mêmes – puisque, dans cette société qui n’a de courtoise que le nom, elles ne peuvent s’accomplir que par la ruse et la dissimulation – n’ont peut-être pas d’autre avenir que dans les sphères de la fiction.Although it has been established that the words that make up the love dialogue between the novel’s characters, Guillem de Nevers and Flamenca, originated in Peire Rogier’s verses (Ges non puesc en bon vers fallir, sixth cobla) or in those, inspired by the former, by Guiraut de Borneil (– Ai las, com mor ! – Quez as, amis ?), the link between Guillem de Nevers and Peire Rogier becomes even more obvious if we take into account the latter’s vida and the cobla dedicated to him by Peire d’Alvernhe in his satirical song Cantarai d’aqestz trobadors. In this song, part of Peire d’Alvernhe’s advice to Peire Rogier – namely, that instead of singing about love in front of everyone, he should hold a psalter in church ̶ further tightens the ties between the troubadour and the character in the novel. It seems that the author of Flamenca had fun fusing the troubadour Peire Rogier into his character in order to have him follow Peire d’Alvernhe’s advice, but redirecting the satire – which was aimed at the troubadour in the song –, towards the religious and, seemingly, courteous society of his novel : he sets up a particularly ingenious game about the symbolism of the psalter and that of the religious man. Indeed, the author amuses himself by making Guillem a cleric whose ordination has no other reason than the love he feels for Flamenca and by making the holy book the medium in which Guillem is able to foresee ̶ through bibliomancy ̶ his love for Flamenca ; the medium also by which peace kisses foreshadow love kisses, and over which he exchanges words of love with Flamenca. In this way, the author ingeniously covers the sacred words and gestures with the ones of the fin’amor in order to suggest to us that the sacred is to be found in the values of the latter, which themselves – since, in this society which is courteous in name only, they can only be accomplished by cunning and dissimulation – perhaps have no other future than in the spheres of fiction
Adaptive deformable mirror dynamics and modular control
No full textThe refractive index of air varies a.o. with temperature, humidity, pressure and the CO2 concentration. Due to atmospheric turbulence this refractive index varies both in space and in time, leading to aberrations in images of light having passed though it. These aberrations limit the achievable resolution of optical telescopes such that the quality of their images is no longer diffraction limited. An adaptive optics (AO) system is a means to recover the diffraction limited quality of the images. This can be achieved a.o. by reflecting the incoming light on a deformable mirror (DM) that adapts its shape to the wavefront of this light such that some norm of the residual wavefront after reflection is minimal. In this thesis novel designs are considered for the DM and its control system. They are primarily aimed at the 8m class of telescopes in visible light, leading to a 200Hz controller bandwidth requirement and 6mm actuator spacing or 5000 actuators on a 500mm diameter DM.. To observe fainter celestial objects and/or increase the image resolution, optical telescopes are foreseen with primary mirrors of up to 40m in diameter. Therefore, the DM system design is aimed at extendibility to a larger number of Degrees Of Freedom (DOF), which is realized using a modular concept. Other drivers are low power consumption to prevent the need for active cooling systems and low production costs. The DM design is realized using electromagnetic reluctance type actuators that are connected to the DM's reflective membrane by a thin rod. Modules containing 61 hexagonally arranged actuators are manufactured using techniques suitable for mass-production. To generate the currents through the actuator coils, driver electronics are developed based on Pulse-Width Modulation (implemented in FPGAs) in combination with analog low-pass filters. Several prototype DMs are realized whose behavior is analyzed both statically and dynamically by comparing Wyko and laser vibrometer measurements with first principle models of the driver electronics, the actuators and the facesheet. To retain modularity of the system, a distributed control system architecture is foreseen in which each (group of) actuator(s) has its own controller that has a fixed computational power, communicates only to its neighbors and receives only a subset of the wavefront measurement data. The design of a distributed controller with good performance is complicated by the wavefront reconstruction step made necessary by the Shack-Hartmann wavefront sensor. Nevertheless, a distributed algorithm that combines wavefront reconstruction with adaptive prediction is shown in simulation to approximate the performance of a centralized finite impulse response (FIR) predictor/reconstructor and does not deteriorate as the number of DOFs increases.DCSCMechanical, Maritime and Materials Engineerin
The computational power of astrocyte mediated synaptic plasticity
Get PDFResearch in the last two decades has made clear that astrocytes play a crucial role in the brain beyond their functions in energy metabolism and homeostasis. Many studies have shown that astrocytes can dynamically modulate neuronal excitability and synaptic plasticity, and might participate in higher brain functions like learning and memory. With the plethora of astrocyte-mediated signaling processes described in the literature today, the current challenge is to identify which of these processes happen under what physiological condition, and how this shapes information processing and, ultimately, behavior. To answer these questions will require a combination of advanced physiological, genetical and behavioral experiments. Additionally, mathematical modeling will prove crucial for testing predictions on the possible functions of astrocytes in neuronal networks, and to generate novel ideas as to how astrocytes can contribute to the complexity of the brain. Here, we aim to provide an outline of how astrocytes can interact with neurons. We do this by reviewing recent experimental literature on astrocyte-neuron interactions, discussing the dynamic effects of astrocytes on neuronal excitability and short- and long-term synaptic plasticity. Finally, we will outline the potential computational functions that astrocyte-neuron interactions can serve in the brain. We will discuss how astrocytes could govern metaplasticity in the brain, how they might organize the clustering of synaptic inputs, and how they could function as memory elements for neuronal activity. We conclude that astrocytes can enhance the computational power of neuronal networks in previously unexpected ways
Presynaptic NMDA Receptors Influence Ca2+ Dynamics by Interacting with Voltage-Dependent Calcium Channels during the Induction of Long-Term Depression.
Get PDFSpike-timing-dependent long-term depression (t-LTD) of glutamatergic layer (L)4-L2/3 synapses in developing neocortex requires activation of astrocytes by endocannabinoids (eCBs), which release glutamate onto presynaptic NMDA receptors (preNMDARs). The exact function of preNMDARs in this context is still elusive and strongly debated. To elucidate their function, we show that bath application of the eCB 2-arachidonylglycerol (2-AG) induces a preNMDAR-dependent form of chemically induced LTD (eCB-LTD) in L2/3 pyramidal neurons in the juvenile somatosensory cortex of rats. Presynaptic Ca2+ imaging from L4 spiny stellate axons revealed that action potential (AP) evoked Ca2+ transients show a preNMDAR-dependent broadening during eCB-LTD induction. However, blockade of voltage-dependent Ca2+ channels (VDCCs) did not uncover direct preNMDAR-mediated Ca2+ transients in the axon. This suggests that astrocyte-mediated glutamate release onto preNMDARs does not result in a direct Ca2+ influx, but that it instead leads to an indirect interaction with presynaptic VDCCs, boosting axonal Ca2+ influx. These results reveal one of the main remaining missing pieces in the signaling cascade of t-LTD at developing cortical synapses
Modeling mind and matter: reductionism and psychological measurement in cognitive neuroscience
Get PDFThe article presents the author's response to an article related to reductionism and psychological measurement in cognitive neuroscience by Rogier A. Kievit and Denny Borsboom, published in a previous issue of the periodical. The author says that the commentaries by the writers in the article suggests that the implementation of conceptually guided psychometric models is viable. He also focuses on the relation between people and reductionism mentioned by the writers in the article
Anleitung Zu der Frantzösischen Sprach/ Begreiffend was anfänglich/ diese Sprach zuerlernen/ am allernöhtigsten sey: Der Jugend Teutscher Nation: zu besten verfertiget
Get PDFANLEITUNG ZU DER FRANTZÖSISCHEN SPRACH/ BEGREIFFEND WAS ANFÄNGLICH/ DIESE SPRACH ZUERLERNEN/ AM ALLERNÖHTIGSTEN SEY: DER JUGEND TEUTSCHER NATION: ZU BESTEN VERFERTIGET
Anleitung Zu der Frantzösischen Sprach/ Begreiffend was anfänglich/ diese Sprach zuerlernen/ am allernöhtigsten sey: Der Jugend Teutscher Nation: zu besten verfertiget
Anleitung Zu der Frantzösischen Sprach/ Begreiffend was anfänglich/ diese Sprach zuerlernen/ am allernöhtigsten sey: Der Jugend Teutscher Nation: zu besten verfertiget (Theil 2) ([1]r)
Anleitung Zu der Frantzösischen Sprach/ Begreiffend was anfänglich/ diese Sprach zuerlernen/ am allernöhtigsten sey: Der Jugend Teutscher Nation: zu besten verfertiget (Forts.) ([1]r
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