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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
121

Identification of novel small molecule inhibitors of proteins required for genomic maintenance and stability

Shuck, Sarah C. 29 July 2010 (has links)
Indiana University-Purdue University Indianapolis (IUPUI) / Targeting uncontrolled cell proliferation and resistance to DNA damaging chemotherapeutics using small molecule inhibitors of proteins involved in these pathways has significant potential in cancer treatment. Several proteins involved in genomic maintenance and stability have been implicated both in the development of cancer and the response to chemotherapeutic treatment. Replication Protein A, RPA, the eukaryotic single-strand DNA binding protein, is essential for genomic maintenance and stability via roles in both DNA replication and repair. Xeroderma Pigmentosum Group A, XPA, is required for nucleotide excision repair, the main pathway cells employ to repair bulky DNA adducts. Both of these proteins have been implicated in tumor progression and chemotherapeutic response. We have identified a novel small molecule that inhibits the in vitro and cellular ssDNA binding activity of RPA, prevents cell cycle progression, induces cytotoxicity and increases the efficacy of chemotherapeutic DNA damaging agents. These results provide new insight into the mechanism of RPA-ssDNA interactions in chromosome maintenance and stability. We have also identified small molecules that prevent the XPA-DNA interaction, which are being investigated for cellular and tumor activity. These results demonstrate the first molecularly targeted eukaryotic DNA binding inhibitors and reveal the utility of targeting a protein-DNA interaction as a therapeutic strategy for cancer treatment.
122

Novel Roles of Replication Protein A Phosphorylation in Cellular Response to DNA Damage

Serrano, Moises A 01 August 2013 (has links) (PDF)
Human replication protein A (RPA) is an eukaryotic single-stranded DNA binding protein directly involved in a variety of DNA metabolic pathways including replication, recombination, DNA damage checkpoints and signaling, as well as all DNA repair pathways. This project presents 2 novel roles of RPA in the cellular response to DNA damage. The first elucidates the regulation of RPA and p53 interaction by DNA-dependent protein kinase (DNA-PK), ataxia telangiectasia mutated (ATM) and ATM- and Rad3-related (ATR) in homologous recombination (HR). HR and nonhomologous end joining (NHEJ) are 2 distinct DNA double-stranded break (DSB) repair pathways. Here, we report that DNA-PK, the core component of NHEJ, partners with DNA-damage checkpoint kinases ATM, and ATR to synergistically regulate HR repair of DSBs. The regulation was accomplished through modulation of the p53-RPA interaction. We show that upon DNA damage p53 and RPA are freed from the p53–RPA complex. This is done through simultaneous phosphorylation of RPA by DNA-PK, and p53 by ATR and ATM. Neither the phosphorylation of RPA nor that of p53 alone could dissociate the p53-RPA complex; furthermore, disruption of the release significantly compromised HR repair of DSBs. Our results reveal a mechanism for the crosstalk between HR and NHEJ repair through the coregulation of p53–RPA interaction by DNA-PK, ATM and ATR. The second part of this project reveals a novel role of RPA32 phosphorylation in suppressing the signaling of programmed cell death, also known as apoptosis. Our results show that deficiency in RPA32 phosphorylation leads to increased apoptosis after genotoxic stress. Specifically, PARP-1 cleavage, Caspase-3 activation, sub-G1 cell population, annexin V staining and the loss of mitochondrial membrane potential were significantly increased in the phospho-deficient RPA32 cells (PD-RPA32). The lack of RPA phosphorylation also promoted activation of initiator Caspase-9 and effector Caspase-3 and -7. This regulation is dependent on the kinase activity of DNA-PK and is mediated by PUMA through the ATM-p53 pathway. Our results suggest a novel role of RPA phosphorylation in apoptosis that illuminates a new target that lies on the crossroads of DNA repair and cell death, a pivotal point that could be of importance for sensitizing cancer cells to chemotherapy.
123

Temporal contrast-dependent modeling of laser-driven solids: studying femtosecond-nanometer interactions and probing

Garten, Marco 03 May 2023 (has links)
Establishing precise control over the unique beam parameters of laser-accelerated ions from relativistic ultra-short pulse laser-solid interactions has been a major goal for the past 20 years. While the spatio-temporal coupling of laser-pulse and target parameters create transient phenomena at femtosecond-nanometer scales that are decisive for the acceleration performance, these scales have also largely been inaccessible to experimental observation. Computer simulations of laser-driven plasmas provide valuable insight into the physics at play. Nevertheless, predictive capabilities are still lacking due to the massive computational cost to perform these in 3D at high resolution for extended simulation times. This thesis investigates the optimal acceleration of protons from ultra-thin foils following the interaction with an ultra-short ultra-high intensity laser pulse, including realistic contrast conditions up to a picosecond before the main pulse. Advanced ionization methods implemented into the highly scalable, open-source particle-in-cell code PIConGPU enabled this study. Supporting two experimental campaigns, the new methods led to a deeper understanding of the physics of Laser-Wake eld acceleration and Colloidal Crystal melting, respectively, for they now allowed to explain experimental observations with simulated ionization- and plasma dynamics. Subsequently, explorative 3D3V simulations of enhanced laser-ion acceleration were performed on the Swiss supercomputer Piz Daint. There, the inclusion of realistic laser contrast conditions altered the intra-pulse dynamics of the acceleration process significantly. Contrary to a perfect Gaussian pulse, a better spatio-temporal overlap of the protons with the electron sheath origin allowed for full exploitation of the accelerating potential, leading to higher maximum energies. Adapting well-known analytic models allowed to match the results qualitatively and, in chosen cases, quantitatively. However, despite complex 3D plasma dynamics not being reflected within the 1D models, the upper limit of ion acceleration performance within the TNSA scenario can be predicted remarkably well. Radiation signatures obtained from synthetic diagnostics of electrons, protons, and bremsstrahlung photons show that the target state at maximum laser intensity is encoded, previewing how experiments may gain insight into this previously unobservable time frame. Furthermore, as X-ray Free Electron Laser facilities have only recently begun to allow observations at femtosecond-nanometer scales, benchmarking the physics models for solid-density plasma simulations is now in reach. Finally, this thesis presents the first start-to-end simulations of optical-pump, X-ray-probe laser-solid interactions with the photon scattering code ParaTAXIS. The associated PIC simulations guided the planning and execution of an LCLS experiment, demonstrating the first observation of solid-density plasma distribution driven by near-relativistic short-pulse laser pulses at femtosecond-nanometer resolution. / Die Erlangung präziser Kontrolle über die einzigartigen Strahlparameter von laserbeschleunigten Ionen aus relativistischen Ultrakurzpuls-Laser-Festkörper-Wechselwirkungen ist ein wesentliches Ziel der letzten 20 Jahre. Während die räumlich-zeitliche Kopplung von Laserpuls und Targetparametern transiente Phänomene auf Femtosekunden- und Nanometerskalen erzeugt, die für den Beschleunigungsprozess entscheidend sind, waren diese Skalen der experimentellen Beobachtung bisher weitgehend unzugänglich. Computersimulationen von lasergetriebenen Plasmen liefern dabei wertvolle Einblicke in die zugrunde liegende Physik. Dennoch mangelt es noch an Vorhersagemöglichkeiten aufgrund des massiven Rechenaufwands, um Parameterstudien in 3D mit hoher Auflösung für längere Simulationszeiten durchzuführen. In dieser Arbeit wird die optimale Beschleunigung von Protonen aus ultradünnen Folien nach der Wechselwirkung mit einem ultrakurzen Ultrahochintensitäts-Laserpuls unter Einbeziehung realistischer Kontrastbedingungen bis zu einer Pikosekunde vor dem Hauptpuls untersucht. Hierbei ermöglichen neu implementierte fortschrittliche Ionisierungsmethoden für den hoch skalierbaren, quelloffenen Partikel-in-Zelle-Code PIConGPU von nun an Studien dieser Art. Bei der Unterstützung zweier Experimentalkampagnen führten diese Methoden zu einem tieferen Verständnis der Laser-Wake eld-Beschleunigung bzw. des Schmelzens kolloidaler Kristalle, da nun experimentelle Beobachtungen mit simulierter Ionisations- und Plasmadynamik erklärt werden konnten. Im Anschluss werden explorative 3D3V Simulationen verbesserter Laser-Ionen-Beschleunigung vorgestellt, die auf dem Schweizer Supercomputer Piz Daint durchgeführt wurden. Dabei veränderte die Einbeziehung realistischer Laserkontrastbedingungen die Intrapulsdynamik des Beschleunigungsprozesses signifikant. Im Gegensatz zu einem perfekten Gauß-Puls erlaubte eine bessere räumlich-zeitliche Überlappung der Protonen mit dem Ursprung der Elektronenwolke die volle Ausnutzung des Beschleunigungspotentials, was zu höheren maximalen Energien führte. Die Adaptation bekannter analytischer Modelle erlaubte es, die Ergebnisse qualitativ und in ausgewählten Fällen auch quantitativ zu bestätigen. Trotz der in den 1D-Modellen nicht abgebildeten komplexen 3D-Plasmadynamik zeigt die Vorhersage erstaunlich gut das obere Limit der erreichbaren Ionen-Energien im TNSA Szenario. Strahlungssignaturen, die aus synthethischen Diagnostiken von Elektronen, Protonen und Bremsstrahlungsphotonen gewonnen wurden, zeigen, dass der Target-Zustand bei maximaler Laserintensität einkodiert ist, was einen Ausblick darauf gibt, wie Experimente Einblicke in dieses bisher unbeobachtbare Zeitfenster gewinnen können. Mit neuen Freie-Elektronen-Röntgenlasern sind Beobachtungen auf Femtosekunden-Nanometerskalen endlich zugänglich geworden. Damit liegt ein Benchmarking der physikalischen Modelle für Plasmasimulationen bei Festkörperdichte nun in Reichweite, aber Experimente sind immer noch selten, komplex, und schwer zu interpretieren. Zuletzt werden daher in dieser Arbeit die ersten Start-zu-End-Simulationen der Pump-Probe Wechselwirkungen von optischem sowie Röntgenlaser mit Festkörpern mittels des Photonenstreu-Codes ParaTAXIS vorgestellt. Darüber hinaus dienten die zugehörigen PIC-Simulationen als Grundlage für die Planung und Durchführung eines LCLS-Experiments zur erstmaligen Beobachtung einer durch nah-relativistische Kurzpuls-Laserpulse getriebenen Festkörper-Plasma-Dichte, dessen Auflösungsbereich gleichzeitig bis auf Femtosekunden und Nanometer vordrang.
124

Organisatoriska effekter vid implementering av RPA : En kvalitativ studie om medarbetares upplevelser / Organizational effects when implementing RPA

Ekdahl, Irma, Wallin, Josefin January 2023 (has links)
Robotic Process Automation (RPA) is a growing field that is receiving more and more attention. The technology is complex and there can be many different reasons why an organization chooses to implement an RPA system. This study aims to investigate which organizational effects can occur when implementing an RPA solution in a business. The aim is to gain a clearer understanding of the factors that influence the employees' attitude towards the RPA system. By examining how the implementation has looked, the essay will draw attention to important aspects that may have an impact on how the RPA solution is perceived and accepted within the organization. This study also discusses how the implementation process has affected the employees' trust in the RPA robot.  Implementing an RPA robot can free up time from repetitive tasks for an organization's employees. Therefore, this study also aims to investigate what differences employees have experienced on their work motivation after the implementation. The result shows various aspects that affect the staff's ability to develop and build trust in an RPA robot. In addition to this, the study has found that it is of great importance that the organization's management possesses the ability to convey information and knowledge. Finally, the study has observed differences between employees' experiences of work motivation before and after the implementation.
125

Interactions of DNA binding proteins with G-Quadruplex structures at the single molecule level

Ray, Sujay 18 November 2014 (has links)
No description available.
126

​ Soilborne Pathogens Of Strawberry In The Central Coast Region Of California: ​ Survey And Cover Cropping With Wheat For Management Of Macrophomina Phaseolina

Steele, Mary 01 June 2023 (has links) (PDF)
Surveys of the four major soilborne pathogens of strawberry (Fusarium oxysporum f. sp. fragariae, Macrophomina phaseolina, Phytophthora spp., and Verticillium dahliae) to determine their relative prevalence were conducted in Watsonville-Salinas, CA in 2021 and in Santa Maria, CA in 2022. All four major pathogens were detected at relatively similar prevalence in Watsonville-Salinas, between 22% and 31% of sampled fields. In Santa Maria, M. phaseolina was far more prevalent at 52% of sampled fields, the other three falling between 14% and 17%. Additionally replicated greenhouse and field trials were conducted to evaluate the effects of wheat as a single season cover crop on Macrophomina root rot of strawberry and the soil microbiome. Greenhouse trials and the first year of the field trial are described here and demonstrate a lack of substantial disease mitigation or pathogen reduction in the soil following wheat growth compared to no-treatment control. Significant changes were seen in the soil microbiome following wheat growth, including the significant amplification of several bacterial species known to be antagonistic to plant-pathogenic fungi.
127

Den digitala revisorn : En kvalitativ studie om automatiseringsteknikens påverkan på revisionsyrket. / The digital accountant : A qualitative study on the impact of automation technology on the auditing profession.

Bachman, André, Boos, Sonja January 2024 (has links)
Studien undersöker effekterna av automatisering på revisionsyrket. Automatiseringstekniken Robotic Process Automation har varit snabbt framväxande inom finansbranschen de senaste åren och är därför relevant att undersöka. Automatiseringsteknikens påverkan har studerats genom semistrukturerade intervjuer där respondenterna antingen är revisorer som har erfarenhet av yrket både före och efter implementering eller respondenter som arbetar på revisionsbyråer i direkt kontakt med revisorer för utveckling av RPA-processer. Resultatet visar att automatisering av revisionsyrket är ett faktum och att revisionsbyråer bör följa den teknologiska utvecklingen för att vara konkurrenskraftiga på den tävlingsinriktade arbetsmarknaden. Arbetsuppgifterna inom revisionsyrket har knappt förändrats givet automatiseringen utan det handlar snarare om att sättet som arbetsuppgifterna utförs på har förändrats. Genom diverse digitala verktyg och system som implementeras kontinuerligt försöker revisorerna utföra de traditionella arbetsuppgifterna. Slutsatsen är att revisionsbranschen är under kontinuerlig förändring och att revisorer påverkas i form av förändrade arbetssätt i dagsläget medan andra yrkestitlar inom revisionsyrket eventuellt kan påverkas i större utsträckning. / This study explores the effects caused by automation on the auditing profession. The automatization technology Robotic Process Automation has been rapidly emerging within the financial industry in recent years and is therefore relevant to study. The impact of the automatization technology has been studied through semi-structured interviews where the respondents were either accountants who had experience in the profession both before and after the implementation or respondents who work at accounting firms indirect contact with accountants for development of RPA-processes. The results show that automation of the audit profession is a fact and that auditing firms should follow the technological development to be competitive. The tasks within the auditing profession have barely changed because of the automation but the change is rather affecting the way the tasks are performed. Accountants try to perform traditional tasks through various digital systems and tools. The conclusion is that the auditing industry is under continuous change and that accountants are only affected by changed working methods as of now, whilst other personnel within the auditing profession might be affected to a greater extent
128

RPA i offentlig sektor : Översättning av institutionella logiker och lokala idéer

Ohlström, Sebastian, Stenberg, Oscar January 2019 (has links)
Rapid technological development and change in modern society is unprecedented in history.Digitalization and automation of business processes is widely seen as a way of streamliningorganisations and changing institutional settings in them. The impact on individuals andorganisations raison d’etre increases as they face stronger institutional pressure from differentstakeholders. As with every thought that comes to mind, the process of translation tries to remedythe gap in individuals and organisations different outlooks. Grounded in theory of institutionallogics and translation, the authors of this paper set out to approach this institutional complexity byinvestigating it through a lens of these theories. We find that the market and corporate logic areinfluencing all of the organisations, but which of the logics that is most likely to be constituteddepends to a high degree on the local translation process. The translation that is produced dependson the institutional environment that is predominant in the organization. For the organization to besuccessful in rapid technological development and change, a thorough understanding of theincremental institutional complexity is paramount. / Snabb teknisk utveckling och förändring i det moderna samhället är oöverträffad i historien.Digitalisering och automatisering av affärsprocesser ses allmänt som ett sätt att effektiviseraorganisationer och ändra den institutionella sammansättningen i dem. Påverkan på individer ochorganisationers existensberättigande ökar när de står inför starkare institutionellt tryck från olikaintressenter. Översättningsprocessen försöker här avhjälpa klyftan i individers och organisationersolika perspektiv som uppstår när nya idéer får fäste. Grundade i teorin om institutionella logikeroch översättning, försöker författarna till denna uppsats att närma sig denna institutionellakomplexitet genom att använda en lins av dessa teorier. Vi finner att marknads- och företagslogikenpåverkar alla organisationer, men vilken logik som sannolikt kommer att få fäste beror i hög gradpå den lokala översättningsprocessen. Översättningen som produceras beror på den institutionellamiljön som dominerar organisationen. För att organisationen ska lyckas med en snabb tekniskutveckling och förändring, är en grundlig förståelse för den inkrementella institutionellakomplexiteten är avgörande.
129

Análise de impactos ambientais da restauração de um pavimento asfáltico pela Avaliação do Ciclo de Vida / Environmental impact analysis of asphalt pavements rehabilitation by Life Cycle Assessment

Savietto, Júlia Panzarin 07 July 2017 (has links)
A infraestrutura de transportes traz benefícios sociais e econômicos, porém traz também inevitáveis impactos ambientais que não podem ser negligenciados, como supressão da vegetação local e poluição atmosférica. Esses impactos ambientais podem ser quantificados e analisados pela técnica Avaliação do Ciclo de Vida (ACV), que cria a possibilidade de contemplar o aspecto ambiental na tomada de decisões e pode trazer melhor compreensão da cadeia produtiva. Na última década, é crescente a utilização dessa técnica na área de pavimentação, entretanto ainda é pouco usual no Brasil. O objetivo dessa dissertação é avaliar os impactos ambientais produzidos por duas técnicas de restauração de pavimentos asfálticos, comparando-se os resultados de ACV que observaram as fases de produção de materiais e de transportes. Dois cenários de restauração foram estudados, o primeiro considerou uma mistura asfáltica composta exclusivamente por materiais virgens (restauração convencional), e o segundo, considerou uma mistura asfáltica composta por 35% de Reciclado de Pavimento Asfáltico (RPA). As ACV foram procedidas de três maneiras distintas: (a) com o banco de dados e software alemão GaBi e o método EDIP 1997, (b) com o banco de dados da USLCI e pelo método do EDIP 1997, e (c) com software PavementLCA e o método TRACI. Os resultados obtidos a partir dos três diferentes procedimentos indicaram que a restauração com RPA apresentou redução dos impactos ambientais potencias quando comparada com a restauração convencional. Observou-se também que, para a maioria das análises, a atividade que mais contribuiu para os impactos das duas estratégias de restauração foi a de produção dos materiais. A análise de sensibilidade dos resultados obtidos com o GaBi e com o USLCI mostrou diferenças consideráveis, causadas pelas diferentes fontes de dados. Apesar de ser uma técnica em crescimento, a ACV ainda apresenta limitações quando aplicada a pavimentos, sobretudo, pela complexidade de seu ciclo de vida e pelas incertezas que envolvem sua elaboração, assim, estudos sobre ACV devem continuar, a fim de padronizar a técnica para a área e, com o tempo, obter resultados cada vez mais precisos. / Transportation infrastructure brings social and economic benefits, but it also brings unavoidable environmental impacts that can not be neglected, such as suppression of local vegetation and air pollution. These environmental impacts can be quantified and analyzed by the Life Cycle Assessment (LCA) technique, which creates the possibility of contemplating the environmental aspect in decision making and can provide a better understanding of the production chain. In the last decade, the use of this technique in the area of pavement is increasing, although not very usual in Brazil. The goal of this thesis is to analyze the environmental impacts produced by two asphalt pavement rehabilitation techniques, comparing the LCA results of material production and transportation phases. Two rehabilitation scenarios were studied, the first one considering an asphalt mixture composed exclusively by raw materials (conventional rehabilitation), and the second one considered an asphalt mixture composed by 35% of Reclaimed Asphalt Pavement (RAP). The LCA was done in three different ways: (a) with the German database and software GaBi and the EDIP 1997 method, (b) with the USLCI database and the EDIP 1997 method, and (c) with PavementLCA software and the TRACI method. The results obtained from the three different procedures indicated that the rehabilitation with RPA showed reduction of the potential environmental impacts when compared with the conventional rehabilitation. It was also observed that for the majority of the analysis, the activity that contributed the most to the impacts of the two rehabilitation strategies was the material production one. The sensitivity analysis of the results obtained with GaBi and with USLCI showed considerable differences in their values, caused by the different data sources. Although it is a growing technique, LCA still presents limitations when applied to pavements, mainly due to the complexity of its life cycle and the uncertainties involved in its elaboration, so studies about LCA should continue with the aim of standardizing the technique for the area and, over time, achieve increasingly more accurate results.
130

Post-replicative resolution of under-replication

Carrington, James T. January 2017 (has links)
The evolutionary pressure to prevent re-replication by inactivating licensing during S phase leaves higher-eukaryotes with large genomes, such as human cells, vulnerable to replication stresses. Origins licensed in G1 must be sufficient to complete replication as new origins cannot be licensed in response to irreversible replication fork stalling. Interdisciplinary approaches between cellular biology and biophysics predict that replication of the genome is routinely incomplete in G2, even in the absence of external stressors. The frequency of converging replication forks that never terminate due to irreversible stalling (double fork stall), which result in a segment of unreplicated DNA, was modelled using high quality origin-mapping data in HeLa and IMR-90 cells. From this, hypotheses were generated that related an increase in unreplicated segments of DNA to reduced functional origin number. Presented in this thesis is the confirmation of this relation by quantifying chromosome mis-segregation and DNA damage responses when origin number was reduced using RNAi against licensing factors. The number of ultrafine anaphase bridges and 53BP1 nuclear bodies are in remarkable concordance with the theoretical predictions for the number of double fork stalls, indicating that cells are able to tolerate under-replication through such post-replicative cellular responses. 53BP1 preferentially binds to chromatin associated with large replicons, and functions synergistically with dormant origins to protect the stability of the genome. Additional candidates, inspired by common fragile site research, have also been characterised as responders to spontaneous under-replication, and include FANCD2 and MiDAS, which function in early mitosis to facilitate completion of replication before cells enter anaphase. In conclusion, a series of mechanisms that sequentially function throughout the cell cycle protects the stability of the human genome against inevitable spontaneous under-replication brought about by its large size.

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