60 research outputs found
Bibliografia completa di Jean Gottmann
No full textGottmann's geographic literature spans over sixty years of activity -- between 1933 and 1994 -- and is composed of almost 400 titles, about twenty of which are books. Published mostly in French and English, his writings were translated in fourteen languages including Spanish, Portuguese, Italian, Tamil, Dutch, Turkish, Slovenian, Japanese, Polish, Yiddish, German and modern Greek. Jean Gottmann's first official bibliography -- covering his writings between 1933 and 1984 -- was published in Patten, J. (ed.), 1983 in The Expanding City, Essays in honour of Professor Jean Gottmann, London-New York Academic Press, pp. xvii-xxxv. The same bibliography is entirely reprinted, with just one addition relative to 1983, in his volume of the same year: The Coming of the Transactional City, printed in College Park by the University of Maryland's Institute for Urban Studies. A selection of his publications dedicated to urban geography between 1949 and 1987 can be found in Jean Gottmann and Robert Harper, 1990, Since Megalopolis, the Urban Writings of Jean Gottmann, Baltimore and London, The Johns Hopkins University Press, pp. 269-280. Thanks to the partial opening of the Fond Gottmann, housed at the Bibliothèque Nationale de France Département des Cartes et Plans it was possible to verify his entire bibliography on the same notebook where Gottmann kept note of his own publications. Finally, the information in this bibliograhy was compared to the one available from the indexes of those thematic volumes that are selections of previously published essays from different scientific journals. In particular Etudes sur l'Etat d'Israel (1958), Essais sur l'aménagement de l'espace habité (1966), La cité invincible (1983) e Since Megalopolis (1990). We would like to thank Jean-Yves Sarazin, curator of the Fond Gottmann at the Bibliothéque Nationale de France in Paris, for his kind re-reading of the complete bibliography. We would also like to invite the reader that may be informed of recent and/or posthumous publications of Jean Gottmann - not included in this list - to contact the author
The complete bibliography of Jean Gottmann
No full textWith 414 entries, this work presents the most complete and updated version of the bibliography of Jean Gottmann (1915-1994), the French and cosmopolitan geographer, known for his studies of urban geography, and especially for those on the megalopolis of the Northeastern seaboard of the United States. In the 1990s, the posthumous rediscovery of his political geography, and in particular of his concept of iconography, opened the way for a reassessment of his pioneering role in cultural geography and to understand the transition from regional geography to the geography of networks. This bibliography thus constitutes a guide for the historian of geographical thought, indispensable for understanding the genesis and evolution of Gottmann’s overall work and, in general, an invitation to reread the writings of each author in the context of their broader scientific production as well as, of course, in the framework of the scientific and intellectual context of the time
Neuroligins determine synapse maturation and function
No full textSynaptogenesis, the generation and maturation of functional synapses between nerve cells, is an essential step in the development of neuronal networks in the brain. It is thought to be triggered by members of the neuroligin family of postsynaptic cell adhesion proteins, which may form transsynaptic contacts with presynaptic alpha- and beta-neurexins and have been implicated in the etiology of autism. We show that deletion mutant mice lacking neuroligin expression die shortly after birth due to respiratory failure. This respiratory failure is a consequence of reduced GABAergic/glycinergic and glutamatergic synaptic transmission and network activity in brainstem centers that control respiration. However, the density of synaptic contacts is not altered in neuroligin-deficient brains and cultured neurons. Our data show that neuroligins are required for proper synapse maturation and brain function, but not for the initial formation of synaptic contacts
Postsynaptic N-methyl-D-aspartate receptor function requires alpha-neurexins
No full textalpha-Neurexins are neuron-specific cell-surface molecules that are essential for the functional organization of presynaptic Ca2+ channels and release sites. We have now examined postsynaptic glutamate receptor function in a-neurexin knockout (KO) mice by using whole-cell recordings in cultured neocortical slices. Unexpectedly, we find that alpha-neurexins are required for normal activity of N-methyl-D-aspartate (NMDA)- but not alpha-amino-3-hydroxy-5-methyl-4-isoxyzolepropionic acid (AMPA)-type glutamate receptors. In a-neurexin-deficient mice, the ratio of NMDA- to AMPA-receptor currents, recorded as evoked synaptic responses, was diminished approximate to50%. Furthermore, the NMDA-receptor-dependent component of spontaneous synaptic miniature responses was reduced approximate to50%, whereas the AMPA-receptor-dependent component was unaffected. No alterations in the levels of NMDA- or AMPA-receptor proteins were detected. These results suggest that a-neurexins are required to maintain normal postsynaptic NMDA-receptor function. The decrease in NMDA-receptor activity in alpha-neurexin-deficient synapses could be due to a transsynaptic effect on the postsynaptic neuron (i.e., alpha-neurexins on the presynaptic inputs guide postsynaptic NMDA-receptor function) or to a cell-autonomous postsynaptic effect of alpha-neurexins on NMDA-receptor activity. To distinguish between these two possibilities, we cocultured WT GFP-labeled neurons with neocortical slices from alpha-neurexin-deficient or control mice. No difference was found between WT neurons innervated by inputs that contained or lacked alpha-neurexins, indicating that the absence of presynaptic alpha-neurexins alone does not depress postsynaptic NMDA-receptor function. Our data suggest that, in addition to the previously described presynaptic impairments, loss of alpha-neurexins induces postsynaptic changes by a cell-autonomous mechanism.NIMH NIH HHS [R37 MH052804, R37 MH52804-08
Analysis for assessment of logistics performance
No full textFür viele Unternehmen stellt sich beim weltweit wachsenden Güterangebot immer nachdrücklicher die Forderung, technisch anspruchsvolle Produkte in kundenspezifischen Varianten bei kurzen Durchlaufzeiten liefern zu können. Daher sollen Unternehmen eine Strategie der Differenzierung zur Erfüllung der individuellen Kundenwünsche und gleichzeitig eine Strategie zur marktgerechten Preisen verfolgen. Als Faktoren einer erfolgreichen Strategie haben sich dabei die Größen Kosten, Qualität und Zeit durchgesetzt. Daneben haben auch eine kurze Lieferzeit und die Liefertreue eine gleichrangige Bedeutung für den Unternehmenserfolg.Unternehmen mit einer Kombination aus Produkten mit hohem Kundennutzen und mit hoher Logistikleistung sind im Wettbewerb besonders erfolgreich.Dafür ist die Gestaltung wirtschaftlich schlanker und logistisch leistungsstarker Produktionsprozesse erforderlich. Dabei hat Logistik die Aufgabe, die internen Anforderungen nach Wirtschaftlichkeit und Produktivität mit den externen Marktanforderungen nach hoher logistischer Leistung abzugleichen. Die gleichzeitige Erfüllung sowohl logistischer als auch wirtschaftlicher Ziele ist nicht im Sinne einer Gesamtoptimierung möglich, da die Optimierung gemäß einer Zielvorgabe zwangsläufig zur Verschlechterung der Zielerreichung der anderen Größen führt. Bedingt durch die zunehmende Komplexität der Produkte sowie ansteigende Anforderungen der Kunden hinsichtlich der logistischen Leistung ganzer Lieferketten ist zur Optimierung eine unternehmensübergreifende logistische Positionierung von Prozessketten notwendig. Hierzu müssen die Auswirkungen der gewählten Position auf die logistischen und wirtschaftlichen Ziele bekannt sein, um eine Beurteilung treffen zu können. Zur gezielten Veränderung der Position ist darüber hinaus die Kenntnis über das Zusammenwirken dieser Zielgrößen wichtig. Ziel der vorliegenden Arbeit ist es deshalb, eine Beziehung zu entwickeln, die bei der Gestaltung und Planung von Fertigungsprozessketten eingesetzt werden kann. Dadurch können Maßnahmen abgeleitet werden, welche zu einer Verbesserung der Logistikleistung der Gesamtprozesskette führen.Schlagwörter: Produktionslogistik, Logistische Kennlinien, Produktionskennlinie
α-Neurexins couple Ca2+ channels to synaptic vesicle exocytosis
No full textSynapses are specialized intercellular junctions in which cell adhesion molecules connect the presynaptic machinery for neurotransmitter release to the postsynaptic machinery for receptor signalling. Neurotransmitter release requires the presynaptic co-assembly of Ca2+ channels with the secretory apparatus, but little is known about how synaptic components are organized. alpha-Neurexins, a family of > 1,000 presynaptic cell-surface proteins encoded by three genes, link the pre- and postsynaptic compartments of synapses by binding extracellularly to postsynaptic cell adhesion molecules and intracellularly to presynaptic PDZ domain proteins. Using triple-knockout mice, we show that alpha-neurexins are not required for synapse formation, but are essential for Ca2+-triggered neurotransmitter release. Neurotransmitter release is impaired because synaptic Ca2+ channel function is markedly reduced, although the number of cell-surface Ca2+ channels appears normal. These data suggest that alpha-neurexins organize presynaptic terminals by functionally coupling Ca2+ channels to the presynaptic machinery
Silent Synapses in the Developing Rat Visual Cortex: Evidence for Postsynaptic Expression of Synaptic Plasticity
No full textIn the developing visual cortex activity-dependent refinement of synaptic connectivity is thought to involve synaptic plasticity processes analogous to long-term potentiation (LTP). The recently described conversion of so-called silent synapses to functional ones might underlie some forms of LTP. Using whole-cell recording and minimal stimulation procedures in immature pyramidal neurons, we demonstrate here the existence of functionally silent synapses, i.e., glutamatergic synapses that show only NMDA receptor-mediated transmission, in the neonatal rat visual cortex. The incidence of silent synapses strongly decreased during early postnatal development. After pairing presynaptic stimulation with postsynaptic depolarization, silent synapses were converted to functional ones in an LTP-like manner, as indicated by the long-lasting induction of AMPA receptor-mediated synaptic transmission. This conversion was dependent on the activation of NMDA receptors during the pairing protocol.The selective activation of NMDA receptors at silent synapses could be explained presynaptically by assuming a lower glutamate concentration compared with functional ones. However, we found no differences in glutamate concentration-dependent properties of NMDA receptor-mediated PSCs, suggesting that synaptic glutamate concentration is similar in silent and functional synapses. Our results thus support a postsynaptic mechanism underlying silent synapses, i.e., that they do not contain functional AMPA receptors. Synaptic plasticity at silent synapses might be expressed postsynaptically by modification of nonfunctional AMPA receptors or rapid membrane insertion of AMPA receptors. This conversion of silent synapses to functional ones might play a major role in activity-dependent synaptic refinement during development of the visual cortex.</jats:p
Insulin promotes functional induction of silent synapses in differentiating rat neocortical neurons
No full textImage_1_Differential Properties of the Synaptogenic Activities of the Neurexin Ligands Neuroligin1 and LRRTM2.TIF
No full textSynaptic cell adhesion molecules are well established to exhibit synaptogenic activity when overexpressed in target cells, indicating that they are involved in formation and functional maturation of synapses. The postsynaptic adhesion proteins Neuroligin1 and LRRTM2 both induce synaptic vesicle clusters in presynaptic axons in vitro by transsynaptically interacting with neurexins. In neurons, this is accompanied by the induction of glutamatergic, but not GABAergic synapses. Although the synaptogenic activity of Neuroligin1 has been well characterized, the properties of the synaptogenic activities of other synaptic adhesion molecules are largely unknown. In this paper, we now compared characteristics of the synaptogenic activities of Neuroligin1 and LRRTM2 upon overexpression in cultured mouse cortical neurons. Individual cortical neurons were transfected with Neuroligin1 and LRRTM2 expression plasmids, respectively, and synaptic vesicle clustering in contacting axons was examined by immunostaining for the vesicle membrane protein VAMP2. In immature neurons at 6–7 days in vitro (DIV) both Neuroligin1 and LRRTM2 exhibited strong synaptogenic activity. However, upon further neuronal differentiation only LRRTM2 retained significant synaptogenic activity at 12–13 DIV. A similar differential developmental maturation of the synaptogenic activities of Neuroligin1 and LRRTM2 was observed for the induction of glutamatergic synapses, which were detected by co-immunostaining for VGLUT1 and Homer1. Most interestingly, the synaptogenic activity of Neuroligin1 was strongly dependent on the expression and function of the synaptic adhesion molecule N-cadherin in immature neurons. In contrast, the synaptogenic activity of LRRTM2 was independent of N-cadherin expression and function in both immature (6–7 DIV) and more mature neurons (14–15 DIV). Taken together, our results with overexpression in cultured cortical neurons revealed striking differences in the properties of the synaptogenic activities of Neuroligin1 and LRRTM2, although both transsynaptically interact with presynaptic neurexins.</p
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