1000 resultados para Network Libraries
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Modern urban lifestyle encourages the prolongation of wakefulness, leaving less and less time for sleep. Although the exact functions of sleep remain one of the biggest mysteries in neuroscience, the society is well aware of the negative consequences of sleep loss on human physical and mental health and performance. Enhancing sleep's recuperative functions might allow shortening sleep duration while preserving the beneficial effects of sleep. During sleep, brain activity oscillates across a continuum of frequencies. Individual oscillations have been suggested to underlie distinct functions for sleep and cognition. Gaining control about individual oscillations might allow boosting their specific functions. Sleep spindles are 11 - 15 Hz oscillations characteristic for light non-rapid-eye-movement sleep (NREMS) and have been proposed to play a role in memory consolidation and sleep protection against environmental stimuli. The reticular thalamic nucleus (nRt) has been identified as the major pacemaker of spindles. Intrinsic oscillatory burst discharge in nRt neurons, arising from the interplay of low-threshold (T-type) Ca2+ channels (T channels) and small conductance type 2 (SK2) K+ channels (SK2 channels), underlies this pacemaking function. In the present work we investigated the impact of altered nRt bursting on spindle generation during sleep by studying mutant mice for SK2 channels and for CaV3.3 channels, a subtype of T channels. Using in vitro electrophysiology I showed that nRt bursting was abolished in CaV3.3 knock out (CaV3.3 KO) mice. In contrast, in SK2 channel over-expressing (SK2-OE) nRt cells, intrinsic repetitive bursting was prolonged. Compared to wildtype (WT) littermates, altered nRt burst discharge lead to weakened thalamic network oscillations in vitro in CaV3.3 KO mice, while oscillatory activity was prolonged in SK2-OE mice. Sleep electroencephalographic recordings in CaV3.3 KO and SK2-OE mice revealed that reduced or potentiated nRt bursting respectively weakened or prolonged sleep spindle activity at the NREMS - REMS transition. Furthermore, SK2-OE mice showed more consolidated NREMS and increased arousal thresholds, two correlates of good sleep quality. This thesis work suggests that CaV3.3 and SK2 channels may be targeted in order to modulate sleep spindle activity. Furthermore, it proposes a novel function for spindles in NREMS consolidation. Finally, it provides evidence that sleep quality may be improved by promoting spindle activity, thereby supporting the hypothesis that sleep quality can be enhanced by modulating oscillatory activity in the brain. Le style de vie moderne favorise la prolongation de l'veil, laissant de moins en moins de temps pour le sommeil. Mme si le rle exact du sommeil reste un des plus grands mystres des neurosciences, la socit est bien consciente des consquences ngatives que provoque un manque de sommeil, la fois sur le plan de la sant physique et mentale ainsi qu'au niveau des performances cognitives. Augmenter les fonctions rcupratrices du sommeil pourrait permettre de raccourcir la dure du sommeil tout en en conservant les effets bnfiques. Durant le sommeil, on observe des oscillations travers un continuum de frquences. Il a t propos que chaque oscillation pourrait tre l'origine de fonctions spcifiques pour le sommeil et la cognition. Pouvoir de contrler les oscillations individuelles permettrait d'augmenter leurs fonctions respectives. Les fuseaux sont des oscillations de 11 15 Hz caractristiques du sommeil ondes lentes lger et il a t suggr qu'elles jouent un rle majeur pour la consolidation de la mmoire ainsi que dans la protection du sommeil contre les stimuli environnementaux. Le nucleus rticulaire du thalamus (nRt) a t identifi en tant que gnrateur de rythme des fuseaux. Les bouffes oscillatoires intrinsques des neurones du nRt, provenant de l'interaction de canaux calciques bas seuil de type T (canaux T) et de canaux potassiques faible conductance de type 2 (canaux SK2), sont l'origine de la fonction de gnrateur de rythme. Dans ce travail, j'ai tudi l'impact de la modulation de bouffes de nRT sur la gnration des fuseaux pendant le sommeil en investiguant des souris gntiquement modifies pour les canaux SK2 et les canaux CaV3.3, un sous-type de canaux T. En utilisant l'lectrophysiologie in vitro j'ai dmontr que les bouffes du nRT taient abolies dans les souris knock-out du type CaV3.3 (CaV3.3 KO). D'autre part, dans les cellules nRT sur-exprimant les canaux SK2 (SK2-OE), les bouffes oscillatoires intrinsques taient prolonges. Par rapport aux souris wild type, les souris CaV3.3 KO ont montr un affaiblissement des oscillations thalamiques en rponse un changement des bouffes de nRT, alors que l'activit oscillatoire tait prolonge dans les souris SK2-OE. Des enregistrements EEG du sommeil dans des souris de type CaV3.3 KO et SK2-OE ont rvl qu'une rduction ou augmentation des bouffes nRT ont respectivement affaibli ou prolong l'activit des fuseaux durant les transitions du sommeil ondes lentes au sommeil paradoxal. De plus, les souris SK2-OE ont montr des signes de consolidation du sommeil ondes lentes et un seuil augment pour le rveil, deux mesures qui corrlent avec une bonne qualit du sommeil. Le travail de cette thse propose que les canaux CaV3.3 et SK2 pourrait tre cibls pour moduler l'activit des fuseaux. De plus, je propose une fonction nouvelle pour les fuseaux dans la consolidation du sommeil ondes lentes. Finalement je suggre que la qualit du sommeil peut tre amliore en promouvant l'activit des fuseaux, soutenant ainsi l'ide que la qualit du sommeil peut tre amliore en modulant l'activit oscillatoire dans le cerveau.
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Cancer genomes frequently contain somatic copy number alterations (SCNA) that can significantly perturb the expression level of affected genes and thus disrupt pathways controlling normal growth. In melanoma, many studies have focussed on the copy number and gene expression levels of the BRAF, PTEN and MITF genes, but little has been done to identify new genes using these parameters at the genome-wide scale. Using karyotyping, SNP and CGH arrays, and RNA-seq, we have identified SCNA affecting gene expression ('SCNA-genes') in seven human metastatic melanoma cell lines. We showed that the combination of these techniques is useful to identify candidate genes potentially involved in tumorigenesis. Since few of these alterations were recurrent across our samples, we used a protein network-guided approach to determine whether any pathways were enriched in SCNA-genes in one or more samples. From this unbiased genome-wide analysis, we identified 28 significantly enriched pathway modules. Comparison with two large, independent melanoma SCNA datasets showed less than 10% overlap at the individual gene level, but network-guided analysis revealed 66% shared pathways, including all but three of the pathways identified in our data. Frequently altered pathways included WNT, cadherin signalling, angiogenesis and melanogenesis. Additionally, our results emphasize the potential of the EPHA3 and FRS2 gene products, involved in angiogenesis and migration, as possible therapeutic targets in melanoma. Our study demonstrates the utility of network-guided approaches, for both large and small datasets, to identify pathways recurrently perturbed in cancer.
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In this paper we present the theoretical and methodologicalfoundations for the development of a multi-agentSelective Dissemination of Information (SDI) servicemodel that applies Semantic Web technologies for specializeddigital libraries. These technologies make possibleachieving more efficient information management,improving agentuser communication processes, andfacilitating accurate access to relevant resources. Othertools used are fuzzy linguistic modelling techniques(which make possible easing the interaction betweenusers and system) and natural language processing(NLP) techniques for semiautomatic thesaurus generation.Also, RSS feeds are used as current awareness bulletinsto generate personalized bibliographic alerts.
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This is the Annual Report for Fiscal Year 2004 (July 1, 2003-June 30, 2004) for the Iowa Communications Network.
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For self-pollinating plants to reproduce, male and female organ development must be coordinated as flowers mature. The Arabidopsis transcription factors AUXIN RESPONSE FACTOR 6 (ARF6) and ARF8 regulate this complex process by promoting petal expansion, stamen filament elongation, anther dehiscence, and gynoecium maturation, thereby ensuring that pollen released from the anthers is deposited on the stigma of a receptive gynoecium. ARF6 and ARF8 induce jasmonate production, which in turn triggers expression of MYB21 and MYB24, encoding R2R3 MYB transcription factors that promote petal and stamen growth. To understand the dynamics of this flower maturation regulatory network, we have characterized morphological, chemical, and global gene expression phenotypes of arf, myb, and jasmonate pathway mutant flowers. We found that MYB21 and MYB24 promoted not only petal and stamen development but also gynoecium growth. As well as regulating reproductive competence, both the ARF and MYB factors promoted nectary development or function and volatile sesquiterpene production, which may attract insect pollinators and/or repel pathogens. Mutants lacking jasmonate synthesis or response had decreased MYB21 expression and stamen and petal growth at the stage when flowers normally open, but had increased MYB21 expression in petals of older flowers, resulting in renewed and persistent petal expansion at later stages. Both auxin response and jasmonate synthesis promoted positive feedbacks that may ensure rapid petal and stamen growth as flowers open. MYB21 also fed back negatively on expression of jasmonate biosynthesis pathway genes to decrease flower jasmonate level, which correlated with termination of growth after flowers have opened. These dynamic feedbacks may promote timely, coordinated, and transient growth of flower organs.
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State Agency Audit Report
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It is well known that multiple-input multiple-output (MIMO) techniques can bring numerous benefits, such as higher spectral efficiency, to point-to-point wireless links. More recently, there has been interest in extending MIMO concepts tomultiuser wireless systems. Our focus in this paper is on network MIMO, a family of techniques whereby each end user in a wireless access network is served through several access points within its range of influence. By tightly coordinating the transmission and reception of signals at multiple access points, network MIMO can transcend the limits on spectral efficiency imposed by cochannel interference. Taking prior information-theoretic analyses of networkMIMO to the next level, we quantify the spectral efficiency gains obtainable under realistic propagation and operational conditions in a typical indoor deployment. Our study relies on detailed simulations and, for specificity, is conducted largely within the physical-layer framework of the IEEE 802.16e Mobile WiMAX system. Furthermore,to facilitate the coordination between access points, we assume that a high-capacity local area network, such as Gigabit Ethernet,connects all the access points. Our results confirm that network MIMO stands to provide a multiple-fold increase in spectralefficiency under these conditions.
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This paper describes a Computer-Supported Collaborative Learning (CSCL) case study in engineering education carried out within the context of a network management course. The case study shows that the use of two computing tools developed by the authors and based on Free- and Open-Source Software (FOSS) provide significant educational benefits over traditional engineering pedagogical approaches in terms of both concepts and engineering competencies acquisition. First, the Collage authoring tool guides and supports the course teacher in the process of authoring computer-interpretable representations (using the IMS Learning Design standard notation) of effective collaborative pedagogical designs. Besides, the Gridcole system supports the enactment of that design by guiding the students throughout the prescribed sequence of learning activities. The paper introduces the goals and context of the case study, elaborates onhow Collage and Gridcole were employed, describes the applied evaluation methodology, anddiscusses the most significant findings derived from the case study.
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In accordance with 2004 IOWA ACTS Chapter 182 (5)(5)(b), the State Library of Iowa submits this report on the uses and impact of state funding provided to Iowa libraries through the Enrich Iowa Program.
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This is the Annual Report for Fiscal Year 2005 (July 1, 2004-June 30, 2005) for the Iowa Communications Network.
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Agency Performance Report
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Agency Performance Report