895 resultados para Controlling chaos


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This paper reports a dendritic system which is capable of forming both one-component and two-component gels interestingly the addition of the second component can either increase or decrease the degree of gelation, depending on dendritic generation.

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Surface patterning in three dimensions is of great importance in biomaterials design for controlling cell behavior. A facile one-step functionalization of biodegradable PDLLA fibers using amphiphilic diblock copolymers is demonstrated here to systematically vary the fiber surface composition. The copolymers comprise a hydrophilic poly[oligo(ethylene glycol) methacrylate] (POEGMA), poly[(2-methacryloyloxy)ethyl phosphorylcholine] (PMPC), or poly[2-(dimethylamino)ethyl methacrylate)] (PDMAEMA) block and a hydrophobic poly(l-lactide) (PLA) block. The block copolymer-modified fibers have increased surface hydrophilicity compared to that of PDLLA fibers. Mixtures of PLAPMPC and PLAPOEGMA copolymers are utilized to exploit microphase separation of the incompatible hydrophilic PMPC and POEGMA blocks at the fiber surface. Conjugation of an RGD cell-adhesive peptide to one hydrophilic block (POEGMA) using thiol-ene chemistry produces fibers with domains of cell-adhesive (POEGMA) and cell-inert (PMPC) sites, mimicking the adhesive properties of the extracellular matrix (ECM). Human mesenchymal progenitor cells (hES-MPs) showed much better adhesion to the fibers with surface-adhesive heterogeneity compared to that to fibers with only adhesive or only inert surface chemistries.

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Insulin signaling to the glomerular podocyte is important for normal kidney function and is implicated in the pathogenesis of diabetic nephropathy (DN). This study determined the role of the insulin receptor substrate 2 (IRS2) in this system. Conditionally immortalized murine podocytes were generated from wild-type (WT) and insulin receptor substrate 2-deficient mice (Irs2−/−). Insulin signaling, glucose transport, cellular motility and cytoskeleton rearrangement were then analyzed. Within the glomerulus IRS2 is enriched in the podocyte and is preferentially phosphorylated by insulin in comparison to IRS1. Irs2−/− podocytes are significantly insulin resistant in respect to AKT signaling, insulin-stimulated GLUT4-mediated glucose uptake, filamentous actin (F-actin) cytoskeleton remodeling and cell motility. Mechanistically, we discovered that Irs2 deficiency causes insulin resistance through up-regulation of the phosphatase and tensin homolog (PTEN). Importantly, suppressing PTEN in Irs2−/− podocytes rescued insulin sensitivity. In conclusion, this study has identified for the first time IRS2 as a critical molecule for sensitizing the podocyte to insulin actions through its ability to modulate PTEN expression. This finding reveals two potential molecular targets in the podocyte for modulating insulin sensitivity and treating DN.

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We calculate and analyze Feshbach resonance spectra for ultracold Yb(1S0)+Yb(3P2) collisions as a function of an interatomic potential scaling factor λ and external magnetic field. We show that, at zero field, the resonances are distributed randomly in λ, but that signatures of quantum chaos emerge as a field is applied. The random zero-field distribution arises from superposition of structured spectra associated with individual total angular momenta. In addition, we show that the resonances with respect to magnetic field in the experimentally accessible range of 400 to 2000 G are chaotically distributed, with strong level repulsion that is characteristic of quantum chaos.

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In Niedersachsen setzt das Ministerium für Wissenschaft und Kultur seit 2007 ein Hochschulkennzahlensystem ein, um einen Teil des Grundhaushalts wettbewerblich an die Hochschulen zu verteilen. Über die Mittelvergabe hinaus ist ein Monitoringsystem integriert, mit dem die Entwicklung der Hochschulen beurteilt werden kann. Zur differenzierten Beurteilung werden monetäre und nichtmonetäre Hochschuldaten zu Kennzahlen verdichtet. Die Kennzahlen befinden sich jedoch auf einer zu hohen Aggregationsebene für ein hochschulinternes Controlling an der Fachhochschule Hannover. Daher dienen Berichtssysteme mit Standardberichten der Information über hochschulweite Prozesse und Ressourcen, um im zunehmenden Wettbewerb der Fachhochschulen fundierte Entscheidungen treffen zu können. Beispielhaft werden Standardberichte zu erbrachten Lehrleistungen als erste Komponente des nichtmonetären Controllings in einem Berichtssystem konzipiert. Methodisch basiert die Konzeption auf einer Informationsbedarfsanalyse mit induktiven und deduktiven Verfahren. Das Vorgehen lässt sich grundsätzlich auf weitere nichtmonetäre Leistungen (z. B. der Forschung) übertragen und in die konzipierte Struktur integrieren.

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Chinese media in the context of China's rise have puzzled many scholars who used to understand media and communications phenomena by employing the theories generated from a few affluent Western democracies, notably the US. As a result, a complex but more accurate picture has been ignored. Under numerous theoretical polarizations, the contemporary social world seems little changed but polarized. This thesis aims to propose a different approach endeavoring to 'de-Westernize' or 'internationalize' media and communications studies. As a starting point, this study focuses on the globalization debate, Chinese media and news agency studies. The thesis has investigated the Chinese news agency, Xinhua, by employing Fuzzy Logic which captures the complexity of the change in the agency's business structure and journalistic practices over last 25 years. The change is also examined by scrutinizing the role of journalists in the interrelations of Xinhua with its news sources, media and nonmedia clients, and other news agencies. A combination of archive study and 94 semistructured interviews conducted in Beijing, Shanghai, Guangzhou, Hong Kong, Macau and London provides an inclusive account of the Chinese news institution. The key research findings drawn from the empirical research into Xinhua have justified the central argument of this thesis: Crisp Logic or the 'either/or' approach has failed to explain the dynamics of the change to the media system based in a 'non-Western' society. The numerous theoretical polarizations generated by Crisp Logic to a large extent have distorted the understanding of the contemporary social world by polarizing it. Fuzzy Logic serves better(though it is not the only choice)than the traditional approach to reflect on the set of variables existing between the two poles created by Crisp Logic. This thesis is the first doctorate research in the UK and other English-speaking countries to investigate Xinhua by 'going inside' the news institution's headquarters, local branches and overseas bureaus. This is the first comprehensive academic study of the agency, which not only examines the agency's recent change in business structure and journalistic practices, but also provides a historical account of the agency and its relationship with other social institutions. This is the first media study that employs Fuzzy Logic to understand the globalization theory, Chinese media and news agencies.

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Synaptic recruitment of AMPA receptors (AMPARs) represents a key postsynaptic mechanism driving functional development and maturation of glutamatergic synapses. At immature hippocampal synapses, PKA-driven synaptic insertion of GluA4 is the predominant mechanism for synaptic reinforcement. However, the physiological significance and molecular determinants of this developmentally restricted form of plasticity are not known. Here we show that PKA activation leads to insertion of GluA4 to synaptic sites with initially weak or silent AMPAR-mediated transmission. This effect depends on a novel mechanism involving the extreme C-terminal end of GluA4, which interacts with the membrane proximal region of the C-terminal domain to control GluA4 trafficking. In the absence of GluA4, strengthening of AMPAR-mediated transmission during postnatal development was significantly delayed. These data suggest that the GluA4-mediated activation of silent synapses is a critical mechanism facilitating the functional maturation of glutamatergic circuitry during the critical period of experience-dependent fine-tuning.

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Dissertação para a obtenção do grau de doutor em Biologia pelo Instituto de Tecnologia Química e Biológica. Universidade Nova de Lisboa.

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A key aspect of glucose homeostasis is the constant monitoring of blood glucose concentrations by specific glucose sensing units. These sensors, via stimulation of hormone secretion and activation of the autonomic nervous system (ANS), regulate tissue glucose uptake, utilization or production. The best described glucose detection system is that of the pancreatic beta-cells which controls insulin secretion. Secretion of other hormones, in particular glucagon, and activation of the ANS, are regulated by glucose through sensing mechanisms which are much less well characterized. Here I review some of the studies we have performed over the recent years on a mouse model of impaired glucose sensing generated by inactivation of the gene for the glucose transporter GLUT2. This transporter catalyzes glucose uptake by pancreatic beta-cells, the first step in the signaling cascade leading to glucose-stimulated insulin secretion. Inactivation of its gene leads to a loss of glucose sensing and impaired insulin secretion. Transgenic reexpression of the transporter in GLUT2/beta-cells restores their normal secretory function and rescues the mice from early death. As GLUT2 is also expressed in other tissues, these mice were then studied for the presence of other physiological defects due to absence of this transporter. These studies led to the identification of extra-pancreatic, GLUT2-dependent, glucose sensors controlling glucagon secretion and glucose utilization by peripheral tissues, in part through a control of the autonomic nervous system.

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Liiketoiminnan organisoiminen projekteiksi on erittäin yleistä nykyisin. Suuri osa projekteista erityisesti IT-alalla epäonnistuu kuitenkin saavuttamaan tavoitteensa. Projektin menestys on tyypillisesti mitattu budjetin, aikataulun, laadun ja sidosryhmien tyytyväisyyden perusteella. Tämän Pro Gradu -tutkielman tarkoituksena on etsiä tyypillisimpiä syitä projektien epäonnistumiseen ja löytää projektien seurannan ja mittaamisen avulla keinoja näiden epäonnistumisten ehkäisemiseen. Tutkimusmenetelmänä on laadullinen tapaustutkimus. Empiirinen aineisto on kerätty haastattelujen, eri materiaalien analysoinnin ja havainnoinnin avulla. Teoriaosuus tarjoaa kattavan yhteenvedon projektiliiketoiminnan ja yksittäisten projektien johtamiseen sekä projektien seurantaan ja mittaamiseen aikaisemman kirjallisuuden perusteella. Empiirisessä osiossa suoritetaan analyysi Case -yrityksen projektien seurantaan ja valittuihin projekteihin. Analyysien, haastattelujen ja havainnoinnin pohjalta tehdään johtopäätökset tyypillisimmistä, ongelmia projekteissa aiheuttavista tekijöistä sekä näiden esiintymisestä projektin elinkaaren eri vaiheissa. Mahdolliset ongelmia ehkäisevät keinot esitetään myös. Ehdotuksia kehityskohteiksi esitetään lopuksi teorian ja empirian pohjalta.