1,818 research outputs found

    Metafizička misija ĆŸene

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    Development and application of analytical methodology with the combined use of gold nanoparticles and aptamers for the colorimetric detection of Pseudomonas aeruginosa

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    Tese (doutorado) - Universidade Federal de Santa Catarina, Centro TecnolĂłgico, Programa de PĂłs-Graduação em Engenharia QuĂ­mica, FlorianĂłpolis, 2022.Pseudomonas aeruginosa Ă© um patĂłgeno responsĂĄvel por causar doenças em todo o mundo. É uma bactĂ©ria Gram-negativa frequentemente encontrada em ambientes terrestres, aquĂĄticos e hospitalar. Devido Ă s grandes contaminaçÔes por essa bactĂ©ria, objetivou-se estudar a detecção colorimĂ©trica deste patĂłgeno atravĂ©s da utilização de aptĂąmeros, que sĂŁo oligonucleotĂ­deos de fita simples de alta afinidade e especificidade, capazes de ligar-se ao alvo, conjugados a nanopartĂ­culas de ouro. Devido Ă  especificidade e afinidade destes, as nanopartĂ­culas de ouro sĂŁo liberadas e as mesmas agregam-se, fazendo com que a solução passe da cor vermelha para roxo, indicando a presença do contaminante. Neste trabalho, os aptĂąmeros para detecção de P. aeruginosa foram conjugados a nanopartĂ­culas de ouro e incubados com a bactĂ©ria alvo apĂłs ensaios para verificar a concentração de NaCl e aptĂąmero ideal. JĂĄ a especificidade do aptĂąmero foi verificada com as bactĂ©rias Staphylococcus aureus, Escherichia coli, Salmonella Typhimurium, Enterobacteriaceae bacterium. Foi observado que os aptĂąmeros conjugados Ă s nanopartĂ­culas de ouro alteraram entre vermelho e roxo na presença de NaCl em concentraçÔes acima que 150 mM, desestabilizando as nanopartĂ­culas de ouro, mas na presença dos aptĂąmeros adsorvidos, a solução permaneceu estĂĄvel. Neste estudo, foi observado que a tĂ©cnica desenvolvida foi capaz de detectar a presença de P. aeruginosa atravĂ©s da mudança de cor de vermelho para roxo nas concentraçÔes de 108 UFC·mL-1 a 105 UFC·mL-1 apĂłs 5 horas de incubação. Assim, foi desenvolvido um biossensor capaz de ligar-se ao alvo em estudo de forma rĂĄpida, comparado a mĂ©todos convencionais. A identificação visĂ­vel foi possĂ­vel devido Ă  mudança de coloração da solução, em concentraçÔes de 108 a 105 UFC·mL-1, podendo auxiliar a detecção de P. aeruginosa em setores hospitalares.Abstract: Pseudomonas aeruginosa is a pathogen responsible for causing disease worldwide. It is a Gram-negative bacterium frequently found in terrestrial, aquatic, and hospital environments. Due to the great contamination by this bacterium, the objective of this work was to study the pathogen colorimetric detection through the use of aptamers, which are single-stranded oligonucleotides of high affinity and specificity, capable of binding to the target, conjugated to gold nanoparticles. Due to their specificity and affinity, the gold nanoparticles are released and they aggregate, changing the dispersion color from red to blue, indicating the presence of the contaminant. In this work, the aptamer for P. aeruginosa detection was conjugated to gold nanoparticles and incubated with the target bacteria after assays to verify the ideal concentration of NaCl and aptamer. The aptamer specificity was verified with the bacteria Staphylococcus aureus, Escherichia coli, Salmonella Typhimurium, and Enterobacteriaceae bacterium. It was observed that aptamers conjugated to the gold nanoparticles changed between red and blue in the presence of NaCl at concentrations above 150 mM, destabilizing the gold nanoparticles, but in the presence of the adsorbed aptamers, the dispersion remained stable. In this study, it was observed that the technique developed was able to detect P. aeruginosa through the color change from red to blue at concentrations from 108 CFU·mL-1 to 105 CFU·mL-1 after 5 h of incubation. Thus, a biosensor was developed to recognize the target rapidly when compared to conventional methods. A visible identification was possible through the change in color of the dispersion, at concentrations of 108 to 105 CFU/mL, which may help the detection of P. aeruginosa in hospital sectors

    AnsÀtze einer Algorithmischen Anwendung Quantititiver Verfahren zur Effizienten Bedarfsprognose von Vorprodukten. Erste Ergebnisse Einer Empirischen Untersuchung

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    ZufĂ€llig schwankende Nachfragen nach Vorprodukten bzw. Teilen und Komponenten machen die Verwendung von stochastischen Modellen der Lagerhaltung notwendig. Das vorliegende Papier beschreibt einen standardisierten algorithmischen Ansatz, mit dem der Verbrauch von Vorprodukten fĂŒr die ZeitrĂ€ume von drei, sechs oder zwölf Monaten mit Hilfe zeitreihenökonometrischer Verfahren prognostiziert werden kann. Im Rahmen dieses Ansatzes werden fĂŒr jede Vorproduktgruppe die unterschiedlichsten quantitativen Prognosetechniken angewendet. Zu den Techniken zĂ€hlen unter anderem AR-, MA-, ARMA-, ARIMA- und strukturelle Regressionsmodelle. Durch algorithmisches Vorgehen wird aufgrund von GĂŒtekriterien (z. B. die PrognosefĂ€higkeit in einem Testdatensatz) ein optimales Prognosemodell ermittelt, das fĂŒr die Prognose des Bedarfs verwendet wird. FĂŒr alle gewĂ€hlten PrognosezeitrĂ€ume erwies sich das ARMA-Modell der d-differenzierten Zeitreihe als bestes Prognosemodell, gefolgt von einfachen Moving Average und ARIMA-Modellen. Die Bedeutung autoregressiver Verfahren nimmt aber mit der LĂ€nge des Prognosezeitraumes ab. Strukturelle AnsĂ€tze erweisen sich allerdings fast nie als beste Prognosemodelle, auch wenn deren Bedeutung mit der LĂ€nge des Prognosezeitraumes zunimmt. Der algorithmische Ansatz ermöglicht fĂŒr einen erheblichen Teil (rund 60 Prozent) der Vorprodukte eine gute PrognosequalitĂ€t. Die GĂŒte der Prognose verbesserte sich, je seltener ZeitrĂ€ume mit fehlender Nachfrage auftreten. Bei Beachtung ausgearbeiteter Voraussetzungen, dĂŒrfte diese algorithmische – und daher einfach durch den Computer zu ermittelnde – Vorgehensweise, die praktische Aufgabe der Prognose von LagerabflĂŒssen fĂŒr einen erheblichen Teil von Vorprodukten bzw. Teilen und Komponenten vereinfachen.Inventory Management, Forecasting, Material Requirement Planning, Time Series

    CINDERELLA FRUITS AND CULTURAL FORESTS IN PACAYA-SAMIRIA, PERUVIAN AMAZON

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    Potentials of on-line repositioning based on implanted fiducial markers and electronic portal imaging in prostate cancer radiotherapy

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    <p>Abstract</p> <p>Background</p> <p>To evaluate the benefit of an on-line correction protocol based on implanted markers and weekly portal imaging in external beam radiotherapy of prostate cancer. To compare the use of bony anatomy versus implanted markers for calculation of setup-error plus/minus prostate movement. To estimate the error reduction (and the corresponding margin reduction) by reducing the total error to 3 mm once a week, three times per week or every treatment day.</p> <p>Methods</p> <p>23 patients had three to five, 2.5 mm Ø spherical gold markers transrectally inserted into the prostate before radiotherapy. Verification and correction of treatment position by analysis of orthogonal portal images was performed on a weekly basis. We registered with respect to the bony contours (setup error) and to the marker position (prostate motion) and determined the total error. The systematic and random errors are specified. Positioning correction was applied with a threshold of 5 mm displacement.</p> <p>Results</p> <p>The systematic error (1 standard deviation [SD]) in left-right (LR), superior-inferior (SI) and anterior-posterior (AP) direction contributes for the setup 1.6 mm, 2.1 mm and 2.4 mm and for prostate motion 1.1 mm, 1.9 mm and 2.3 mm. The random error (1 SD) in LR, SI and AP direction amounts for the setup 2.3 mm, 2.7 mm and 2.7 mm and for motion 1.4 mm, 2.3 mm and 2.7 mm. The resulting total error suggests margins of 7.0 mm (LR), 9.5 mm (SI) and 9.5 mm (AP) between clinical target volume (CTV) and planning target volume (PTV). After correction once a week the margins were lowered to 6.7, 8.2 and 8.7 mm and furthermore down to 4.9, 5.1 and 4.8 mm after correcting every treatment day.</p> <p>Conclusion</p> <p>Prostate movement relative to adjacent bony anatomy is significant and contributes substantially to the target position variability. Performing on-line setup correction using implanted radioopaque markers and megavoltage radiography results in reduced treatment margins depending on the online imaging protocol (once a week or more frequently).</p
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