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1
Berti, Matteo. "New mechanistic insight into replication fork reversal and restart." Doctoral thesis, Scuola Normale Superiore, 2013. http://hdl.handle.net/11384/85975.
Texte intégralRésumé :
An emerging model of how stalled or damaged forks are processed is that replication
fork
s can reverse to aid repair of the damage. The first evidence that replication forks
regress in human cells came from a recent study with topoisomerase I (T
op
1) inhibitors, an
important class of anticancer drugs currently in clinical use. Their cytotoxicit
y, and thus
their efficacy, has been generally linked to their ability to cause the accumulation of DNA
nicks, which are later converted into double
-
stranded breaks (DSBs) by the collision of the
DNA replication fork with the primary lesion. The discovery
that replic
ation forks can
regress upon Top
1 inhibition provided new insight into
the molecular basis of Top
1
cytotoxicity by showing that clinically relevant
, nanomolar doses of Top
1 poisons induce
replication fork slowing and reversal in a process that c
an be uncoupled from DSB
formation
and
requires poly(ADP
-
ribose) polymerase
1
(
PARP1) activity.
However,
w
hether re
versed
forks can efficiently restart
and wh
ich
factors are
involved in this
mechanism
was
still unknown.
In this thesis
,
u
sing a combination
of biochemical and
cellular approaches, we provided the first evidence that regressed forks can restart
in vivo
and identified a key role for the human RECQ1 helicase in promoting efficient re
plication
fork restart after Top
1 inhibition
that is not shared
by other human RecQ
members
.
Our
data also provided the first insight into the molecular role of PARP1 in fork reversal by
showing that the poly(ADP
-
ribosyl)ation activity of PARP inhibits RECQ1 activity on
replication forks after Top 1 inhibition. Thus, PARP activity is not required to form, but
rather to "accumulate" reversed fork structures by maintaining/protecting them from a
counteracting activity (RECQ1), which would otherwise cause an untimely restart of
reversed forks, leading to DSB formation. The
identification of a specific and controlled
biochemical activity that drives
the
restart of reversed forks strongly supports the
physiological relevance of this DNA transaction during replication stress in human cells.
Moreover, our
studies provide new mec
hanistic insights into the roles of
RECQ1 and
PARP
1
in DNA replication and offer molecular perspectives to potentiate
chemo
therapeutic regimens based on Top
1 inhibition.
2
MENIN, LUCA. "Role of Tel1/ATM in protecting and signaling abnormal replication forks and short telomeres." Doctoral thesis, Università degli Studi di Milano-Bicocca, 2019. http://hdl.handle.net/10281/241165.
Texte intégralRésumé :
Le cellule eucariotiche prevengono l’instabilità genomica attivando un complesso sistema biochimico chiamato Risposta ai Danni al DNA (DDR). Le proteine chinasi Mec1 e Tel1 di S. cerevisiae, ortologhe di ATR ed ATM umane, giocano un ruolo centrale nella DDR. Queste proteine attivano il checkpoint da danni al DNA il quale coordina la riparazione dei danni al DNA con la progressione del ciclo cellulare. Il ruolo della proteina Tel1 è particolarmente evidente in presenza di rotture a doppia elica del DNA (DSB). I DSB possono essere riparati tramite ricombinazione omologa la quale richiede la degradazione dell’estremità 5’ della rottura (resection). Tel1 contribuisce alla riparazione dei DSB promuovendo l’inizio della resection. Nonostante le funzioni di Tel1 nella DDR, l’assenza di Tel1 conferisce alle cellule di lievito solo una moderata sensibilità alla camptotecina (CPT), un inibitore delle topoisomerasi di tipo I. Dato che derivati della CPT sono attualmente usati in chemioterapia, comprendere il ruolo di Tel1 in risposta alla CPT è rilevante per lo sviluppo di nuove terapie anticancro.
Oltre a ciò, Tel1 è importante per il mantenimento dei telomeri, i quali vengono replicati grazie ad una trascrittasi inversa chiamata telomerasi. In particolare, Tel1 promuove il reclutamento della telomerasi e quindi l’omeostasi dei telomeri. La telomerasi è inattivata nella maggior parte dei tessuti umani che di conseguenza sono soggetti ad un progressivo accorciamento dei telomeri. Quando i telomeri divengono criticamente corti, si ha il blocco della divisione cellulare in un processo noto come senescenza replicativa che limita la proliferazione cellulare agendo da meccanismo oncosoppressore. La senescenza è innescata dall’attivazione del checkpoint da danni al DNA governato da Mec1/ATR e Tel1/ATM. In particolare, il meccanismo attraverso il quale Tel1/ATM induce la senescenza è ancora ignoto.
Durante il mio dottorato ho quindi seguito due distinti progetti allo scopo di far luce sui meccanismi molecolari che coinvolgono Tel1 in risposta alla CPT e nell’induzione della senescenza. Riguardo al primo progetto, sia in lievito che in mammifero la CPT induce la reversione delle forche replicative. Cellule tel1∆ sono caratterizzate da un ridotto livello di forche regresse indotte dalla CPT rispetto a cellule selvatiche. In risposta alla CPT, l’assenza dell’attività nucleasica di Mre11 ripristina livelli normali di forche regresse in cellule tel1∆. Inoltre, l’inattivazione della proteina Mrc1 mitiga la sensibilità a CPT di cellule tel1∆ e previene la reversione delle forche in cellule selvatiche, in cellule tel1∆ e in cellule senza l’attività nucleasica di Mre11. Nel loro insieme questi risultati indicano che Tel1 stabilizza le forche regresse generate da Mrc1 in presenza della CPT inibendo l’attività nucleasica di Mre11 a livello di queste strutture di DNA.
Riguardo al secondo progetto, per studiare il ruolo di Tel1 nell’induzione della senescenza ho sfruttato cellule di lievito senza telomerasi e l’allele mutante TEL1-hy184 identificato precedentemente come soppressore dei difetti di checkpoint di cellule mec1∆. Subito dopo l’inattivazione della telomerasi la variante Tel1-hy184 accelera la senescenza rispetto a cellule che esprimono la forma selvatica di Tel1. L’aumentata senescenza indotta da Tel1-hy184 è causata dall’attivazione di un checkpoint completamente dipendente dalla proteina Rad9 e solo in parte dipendente da Mec1. Inoltre, Tel1-hy184 non sembra aumentare il livello di ssDNA alle estremità di DNA. Ciò suggerisce che Tel1 induce la senescenza replicativa contribuendo direttamente all’attivazione del checkpoint in presenza di telomeri disfunzionali.
Nel complesso, i risultati che ho ottenuto durante il mio dottorato permettono di comprendere meglio le funzioni di Tel1/ATM nel mantenimento della stabilità genomica.<br>Eukaryotic cells prevent genomic instability by activating a complex network of safeguard pathways called DNA Damage Response (DDR). S. cerevisiae Mec1 and Tel1 protein kinases, orthologs of human ATR and ATM, play a central role in the DDR. These proteins activate a checkpoint cascade which coordinates DNA damage repair with cell cycle progression. The role of Tel1 is particularly evident in the presence of DNA Double-Strand Breaks (DSBs), one of the most cytotoxic forms of DNA lesions. DSBs can be repaired by Homologous Recombination (HR), which requires the degradation of 5’-ended strands of the break (resection). Tel1 contributes to DSB repair by promoting resection initiation. Despite Tel1 functions in DDR, the absence of Tel1 confers a moderate sensitivity to camptothecin (CPT), an inhibitor of type I DNA topoisomerases. Since CPT derivatives are currently used in chemotherapy, understanding the molecular basis of tel1Δ mutant sensitivity to CPT is relevant for the development of anti-cancer therapies based on combined treatments with CPT derivatives and ATM inhibitors.
In addition, Tel1 is important for the maintenance of telomeres, which are replicated by a reverse transcriptase called telomerase. In particular, Tel1 promotes the recruitment of telomerase and therefore telomere homeostasis. Telomerase is inactivated in most human tissues, which undergo progressive telomere shortening. When telomeres become critically short, a block of cell division, known as replicative senescence, limits cell proliferation, thus acting as a cancer-suppressor mechanism. Senescence is triggered by the activation of a checkpoint response governed by Mec1/ATR and Tel1/ATM. While Mec1/ATR is known to block cell division in the presence of extended ssDNA, the molecular mechanism by which Tel1/ATM triggers senescence is still unclear.
During my PhD I have managed two different projects with the aim to shed light into the molecular mechanisms that involve Tel1 in response to CPT and in the induction of replicative senescence. Regarding the first project, in both yeast and mammals, CPT induces replication fork reversal, which has been proposed to stabilize stalled replication forks, thus providing time for the repair of CPT-induced lesions and supporting replication restart. tel1∆ cells have a reduced amount of CPT-induced reversed forks compared to wild type cells. The lack of Mre11 nuclease activity restores wild-type levels of reversed forks in CPT-treated tel1Δ cells, without affecting fork reversal in wild-type cells. Moreover, Mrc1 inactivation prevents fork reversal in wild-type, tel1Δ, and mre11 nuclease-deficient cells and relieves the hypersensitivity of tel1Δ cells to CPT. Altogether, these data indicate that Tel1 stabilizes Mrc1-dependent reversed forks generated in the presence of CPT by counteracting Mre11 nucleolytic activity at these structures.
Regarding the second project, to studying the role of Tel1/ATM in the induction of senescence, I took advantage of telomerase-deficient yeast cells, which are considered a reliable model of replicative senescence, and the TEL1-hy184 allele, previously identified because it was able to suppress the checkpoint defects of Mec1-deficient cells. Upon telomerase inactivation, Tel1-hy184 accelerates senescence compared to wild type Tel1, while the lack of Tel1 was found to delay senescence. The enhanced senescence in telomerase-negative TEL1-hy184 cells depends on the activation of a checkpoint that is completely Rad9-dependent and only partially dependent on Mec1. Furthermore, Tel1-hy184 does not appear to increase ssDNA at DNA ends, suggesting that Tel1 induces replicative senescence by directly contributing to checkpoint signaling at dysfunctional telomeres.
Taken together, the results that I have obtained during my PhD allow to better understand the functions of Tel1/ATM in the maintenance of genome stability.
3
O'Donoughue, Nicholas A. "Stochastic Time Reversal for Radar Detection." Research Showcase @ CMU, 2011. http://repository.cmu.edu/dissertations/178.
Texte intégralRésumé :
Time Reversal is an adaptive waveform transmission technique particularly suited to dispersive or non-homogenous media that focuses energy on a desired point in space. Early work concentrated on optical and acoustic/ultrasonic applications, followed more recently by applications in the electromagnetic domain. Time Reversal has been used for single- and multi-antenna detection, imaging, communications, non-destructive testing, and beam steering, among other applications.
This thesis develops Time Reversal detection algorithms for randomly varying targets embedded in randomly varying clutter. We model the target and clutter as independent complex Gaussian random variables and consider both single-antenna and multi-antenna detection scenarios. We derive the optimal Time-Reversal Likelihood Ratio Test (TR-LRT) for the single-antenna case, as well as a sub-optimal Time Reversal-Linear Quadratic (TR-LQ) detector that allows for a priori threshold and performance computation. These detectors are compared against a benchmark Weighted Energy Detector (WED). For the multi-antenna scenario, we present the Time Reversal MIMO (TR-MIMO) detector and compare its performance to a conventional Spatial MIMO (S-MIMO) radar. We show that, for both scenarios, the relative performance of Time Reversal detection methods depends on the coherence of the channel between the forward and TR transmission stages. We discuss the potential for detection gains with Time Reversal in single-antenna and multi-antenna systems. We discuss lower and upper bounds on gain and show that Time Reversal provides a useful and computationally simple approximation to the optimal transmit signal.
To compute the optimal hypothesis test for a Blind TR detection system, we derive a new statistical distribution, the Complex Double Gaussian distribution, which characterizes the complex product Z = XY of independent complex Gaussian random variables X and Y . We also apply this new probability distribution to analyze the performance of M-ary Phase Shift Keying (MPSK) communication systems, showing its applicability well beyond the realm of Time Reversal problems.
4
Hallberg, Jonatan, and Joel Winninge. "In-plant reverse logistics: The reversed flow of steel scrap for reuse at Sandvik Materials Technology." Thesis, Linköpings universitet, Kommunikations- och transportsystem, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-119981.
Texte intégralRésumé :
Syftet med denna studie är att kartlägga flödet av returstål inom SMT för att identifiera eventuella problem samt, om så är fallet, presentera förbättringsförslag för att åtgärda dessa. Kartläggningen visade att ett fåtal produktionsenheter står för majoriteten av returstålet som uppstår inom SMT samt att det överlag föreligger brister i sorteringen. Felsorteringen medför kostnader i form av ökad hantering, minskat materialvärde samt problem vid smältningsprocessen i Stålverket. En av anledningarna till felsorteringen är avsaknaden av återkoppling i form av kostnader och sorteringskvalitet till varje produktionsenhet. Det har via kartläggningen framkommit att transportkostnaderna är låga relativt materialvärdet. Därför är det av vikt att returstålet transporteras till Råvarugården snabbt. Resultatet av denna studie är att returstålsflödet skulle bli effektivare genom förbättrad sortering snarare än genom minskade transportkostnader.
5
Lima, Daniel Carneiro de. "Analysis of market forces and state in the formation of reverse chains of steel containers for beverages and lubricating oil in the textile industry." Universidade Federal do CearÃ, 2007. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=3647.
Texte intégralRésumé :
nÃo hÃ<br>This study analyzes the market and governmental forces informing the recycling policies of companies in the beverage can industry and the textile lubricant industry in CearÃ. The two industries were chosen for a comparative study of environmental strategies due to differences in the specific environmental regulation to which they are subjected. Companies in these sectors are adopting more
responsible environmental protection policies as part of their national and international competitive strategies, since consumers and investors are increasingly recognizing the relation between industrial performance and environmental quality. Likewise, regulation is grower stricter regarding accountability for environmental damage. The main stakeholder influences affecting company policy-making were analyzed qualitatively using the model of institutional pressures proposed by Delmas (2004), according to which companies respond to the demands of the market, regulation and other stakeholders in order to increase their competitive advantage. The companies were also analyzed with regard to their environmental strategies and their understanding of and reaction to external pressures in view of their history of environmental performance, competitive position and organizational
structure. The findings for the two industries compared in the study were organized according the model of institutional pressures, relating adopted environmental practices to external pressures and company profile. Environmental practices were evaluated with the help of indicators reflecting the quality of environmental management and its insertion into the overall business system, including general management, human resources, purchasing department, legal department, production,
operation and marketing. The market â informed by international environmental standards â was found
to be the strongest influence on company recycling policies in the beverage can industry. In the case of textile lubricants, these policies were most often determined by the international market and national regulations.<br>O trabalho apresenta uma anÃlise das forÃas de mercados e de Estado que agem sobre a formaÃÃo das cadeias reversas das embalagens de aÃo para bebidas e do Ãleo lubrificante utilizado pela indÃstria tÃxtil. A escolha desses dois setores teve como objetivo a realizaÃÃo de um estudo comparativo da conduta ambiental e estratÃgica das empresas cearenses em um ambiente onde ocorre regulamentaÃÃo especÃfica, como à o caso do Ãleo lubrificante, e onde nÃo existe uma regulamentaÃÃo especÃfica, que caracteriza a cadeia das embalagens de aÃo para bebida. Destaca-se tambÃm o fato de as empresas desses setores adotarem a proteÃÃo ambiental como parte de suas estratÃgias competitivas nacionais e internacionais, pois, tanto os consumidores como os
investidores, estÃo comeÃando a ver com maior clareza as relaÃÃes entre o desempenho comercial e a qualidade ambiental. AlÃm das exigÃncias dos clientes, ressalta-se o fato de as legislaÃÃes terem se tornado mais rigorosas quanto à responsabilidade por danos ambientais. Mediante de uma anÃlise qualitativa, foram avaliadas as principais influÃncias exercidas pelas partes interessadas, segundo o Modelo das PressÃes Institucionais, proposto por Delmas (2004). Com base neste modelo, a empresa responde Ãs exigÃncias dos mercados, da legislaÃÃo e das demais partes interessadas, com o objetivo de obter vantagem competitiva, alÃm de se averiguar o comportamento ambiental das empresas diante da posiÃÃo estratÃgica que ocupam e a maneira como essas percebem e reagem Ãs pressÃes em funÃÃo de fatores especÃficos, tais como: o histÃrico de desempenho ambiental, a posiÃÃo competitiva das empresas-matrizes e a estrutura organizacional das organizaÃÃes. As tÃxteis e as integrantes da cadeia das embalagens de aÃo para bebida no Cearà tiveram os seus resultados organizados segundo o modelo das pressÃes institucionais, que relaciona a adoÃÃo de prÃticas
ambientais em relaÃÃo Ãs pressÃes sofridas e de acordo com as caracterÃsticas das empresas. Avaliou-se tambÃm a conduta ambiental mediante de um conjunto de indicadores que refletem a qualidade do gerenciamento ambiental ao longo do sistema de negÃcios, incluindo administraÃÃo geral, recursos humanos, compras, jurÃdico, produÃÃo e operaÃÃo e marketing. A pesquisa constatou que, no setor das embalagens de aÃo para bebidas, o mercado, influenciado por padrÃes internacionais de conduta ambiental, Ã o que exerce maior influÃncia sobre as empresas para a formaÃÃo da cadeia reversa. JÃ na cadeia reversa do Ãleo lubrificante na indÃstria tÃxtil, constatou-se que os mercados internacionais e a legislaÃÃo nacional sÃo os que exercem maiores influÃncias para a formaÃÃo dessas cadeias reversas.
6
Buss, Amanda Sória. "Proposta de embalagem para logística reversa em projeto de Design para o Território." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2013. http://hdl.handle.net/10183/85034.
Texte intégralRésumé :
A logística reversa de embalagem (LRE) e o design orientado ao território (DT) são abordagens com ênfases diferentes, mas que possuem características que se complementam. A embalagem, por exemplo, surge como uma estratégia com o potencial de comunicação do território e de sustentabilidade ambiental, premissas do DT, através da logística reversa. Este trabalho tem como principal objetivo propor diretrizes e práticas para integração entre essas duas abordagens, LRE e DT. Utilizou-se como unidade de análise um processo de produção orgânica. O método adotado foi a pesquisa-ação, contendo atividades como: (i) revisão de literatura sistematizada para identificação e análise de conceitos, diretrizes, objetivos e ações que permitisse a integração entre a LRE e o DT; (ii) identificação de oportunidades de LRE no contexto do DT a partir do mapeamento de um processo e da sugestão de ferramentas como o blueprint, o Service Failure Mode and Effect Analysis (SFMEA) e a matriz SWOT; (iii) testar as diretrizes de integração propostas em um projeto de embalagens. Dentre os principais resultados do trabalho estão a apresentação de um conjunto de diretrizes norteadoras de LRE em projetos de DT; um diagnóstico de oportunidade de LRE em um projeto de DT, no caso o dos produtores de hortaliças orgânicas; proposição de uma ferramenta para avaliação da integração entre as abordagens e o grau de formalismo presente no planejamento e na gestão da LRE, denominada RADAR DT-LRE; o replanejamento do sistema logístico e o projeto de embalagens; e a aplicação da ferramenta RADAR DT-LRE. Constatou-se que as diretrizes, objetivos e ações integradas entre LRE e DT nortearam de forma satisfatória o sistema de LRE e o projeto das embalagens no caso investigado, apresentando melhorias em relação seu ao estado inicial. As diretrizes com destaque foram: proteção e perpetuação da identidade e do patrimônio, desenvolvimento econômico, redução do impacto ambiental; melhoria da imagem da empresa/negócio e, em menor grau, infraestrutura de suporte ao sistema de logística reversa de embalagens.<br>The packaging reverse logistics (PRL) and the territorial design (TD) are approaches with different emphases, but that have characteristics that complement each other. The packaging, for example, appears as a strategy with the potential for territory communication and environmental sustainability - assumptions of TD - through reverse logistics. The main of this work is to propose guidelines and practices for integration between the two approaches, PRL and TD. A process of organic production was used as the analysis unit. The method adopted was the action research, containing activities such as: (i) systematic literature review to identify and analyze concepts, guidelines, objectives and actions that allow integration between the PRL and TD; (ii) identification of opportunities for PRL in the context of TD, from a process mapping and suggestion of tools such as blueprint, Service Failure Mode and Effect Analysis (SFMEA) SWOT matrix; and (iii) testing the integration guidelines proposed in a packaging project. The main results of the work are: presenting a set of guidelines for PRL in TD projects; a diagnosis of a opportunity of PRL in a TD project; proposal of a tool to evaluate the level of integration between the two approaches and the degree of formality present in the planning and in the management of PRL, called Radar TD-PRL; redesign of the logistics system and packaging design, and implementation of the tool RADAR TD-PRL. It was found that the guidelines, objectives and integrated actions between PRL and TD guided satisfactorily the PRL system and the packaging design in the investigated case, showing improvements compared to its initial state. The featured guidelines are: protection and perpetuation of identity and heritage, economic development, reduced environmental impact, improving the company's image / business, and, to a lesser extent, infrastructure support system for PRL.
7
Lopez-Castellanos, Victor. "Ultrawideband Time Domain Radar for Time Reversal Applications." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1301040987.
Texte intégral
8
Wang, Daniel Y. "Spatiotemporal processing and time-reversal for underwater acoustic communications." Thesis, Massachusetts Institute of Technology, 2005. http://handle.dtic.mil/100.2/ADA455115.
Texte intégral
9
Walther, Andrea. "Program Reversal Schedules for Single- and Multi-processor Machines." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2002. http://nbn-resolving.de/urn:nbn:de:swb:14-1011612099250-05302.
Texte intégralRésumé :
Bei der Berechnung von Adjungierten, zum Debuggen und für ähnliche Anwendungen kann man die Umkehr der entsprechenden Programmauswertung verwenden. Der einfachste Ansatz, nämlich das Mitschreiben einer kompletten Mitschrift der Vorwärtsrechnung, welche anschließend rückwärts gelesen wird, verursacht einen enormen Speicherplatzbedarf. Als Alternative dazu kann man die Mitschrift auch stückweise erzeugen, indem die Programmauswertung von passend gewählten Checkpoints wiederholt gestartet wird. Das Ziel der Arbeit ist die Minimierung des von der Programmumkehr verursachten Zeit- und Speicherplatzbedarfs. Dieser wird gemessen in Auswertungswiederholungen bzw. verwendeten Checkpoints. Optimale Umkehrschemata werden für Ein- und Mehr-Schritt-Verfahren entwickelt, welche zum Beispiel bei der Diskretisierung einer gewöhnlichen Differentialgleichung Verwendung finden. Desweiteren erfolgte die Entwicklung von parallelen Umkehrschemata, d. h. mehrere Prozessoren werden für die Umkehrung der Programmauswertung eingesetzt. Diese zusätzlichen Prozessoren dienen dazu, die wiederholten Berechnungen des Programms zu parallelisieren, so daß ein Prozessor die Rückwartsrechnung ohne Unterbrechung durchführen kann. Sowohl für die seriellen als auch für die parallelen Umkehrschemata wurde gezeigt, daß die Länge der umzukehrenden Programmauswertung exponentiell in Abhängigkeit von der Zahl der verwendeten Checkpoints und der Zahl der wiederholten Auswertungen bzw. verwendeten Prozessoren wächst<br>For adjoint calculations, parameter estimation, and similar purposes one may need to reverse the execution of a computer program. The simplest option is to record a complete execution log and then to read it backwards. This requires massive amounts of storage. Instead one may generate the execution log piecewise by restarting the ``forward'' calculation repeatedly from suitably placed checkpoints. The basic structure of the resulting reversal schedules is illustrated. Various strategies are analysed with respect to the resulting temporal and spatial complexity on serial and parallel machines. For serial machines known optimal compromises between operations count and memory requirement are explained, and they are extended to more general situations. For program execution reversal on multi-processors the new challenges and demands on an optimal reversal schedule are described. We present parallel reversal schedules that are provably optimal with regards to the number of concurrent processes and the total amount of memory required
10
Walther, Andrea. "Program Reversal Schedules for Single- and Multi-processor Machines." Doctoral thesis, Technische Universität Dresden, 1999. https://tud.qucosa.de/id/qucosa%3A24113.
Texte intégralRésumé :
Bei der Berechnung von Adjungierten, zum Debuggen und für ähnliche Anwendungen kann man die Umkehr der entsprechenden Programmauswertung verwenden. Der einfachste Ansatz, nämlich das Mitschreiben einer kompletten Mitschrift der Vorwärtsrechnung, welche anschließend rückwärts gelesen wird, verursacht einen enormen Speicherplatzbedarf. Als Alternative dazu kann man die Mitschrift auch stückweise erzeugen, indem die Programmauswertung von passend gewählten Checkpoints wiederholt gestartet wird. Das Ziel der Arbeit ist die Minimierung des von der Programmumkehr verursachten Zeit- und Speicherplatzbedarfs. Dieser wird gemessen in Auswertungswiederholungen bzw. verwendeten Checkpoints. Optimale Umkehrschemata werden für Ein- und Mehr-Schritt-Verfahren entwickelt, welche zum Beispiel bei der Diskretisierung einer gewöhnlichen Differentialgleichung Verwendung finden. Desweiteren erfolgte die Entwicklung von parallelen Umkehrschemata, d. h. mehrere Prozessoren werden für die Umkehrung der Programmauswertung eingesetzt. Diese zusätzlichen Prozessoren dienen dazu, die wiederholten Berechnungen des Programms zu parallelisieren, so daß ein Prozessor die Rückwartsrechnung ohne Unterbrechung durchführen kann. Sowohl für die seriellen als auch für die parallelen Umkehrschemata wurde gezeigt, daß die Länge der umzukehrenden Programmauswertung exponentiell in Abhängigkeit von der Zahl der verwendeten Checkpoints und der Zahl der wiederholten Auswertungen bzw. verwendeten Prozessoren wächst.<br>For adjoint calculations, parameter estimation, and similar purposes one may need to reverse the execution of a computer program. The simplest option is to record a complete execution log and then to read it backwards. This requires massive amounts of storage. Instead one may generate the execution log piecewise by restarting the ``forward'' calculation repeatedly from suitably placed checkpoints. The basic structure of the resulting reversal schedules is illustrated. Various strategies are analysed with respect to the resulting temporal and spatial complexity on serial and parallel machines. For serial machines known optimal compromises between operations count and memory requirement are explained, and they are extended to more general situations. For program execution reversal on multi-processors the new challenges and demands on an optimal reversal schedule are described. We present parallel reversal schedules that are provably optimal with regards to the number of concurrent processes and the total amount of memory required.
11
Brevis, Vergara Rodrigo Ignacio. "Source time reversal methods for acoustic and elastic waves." Tesis, Universidad de Chile, 2018. http://repositorio.uchile.cl/handle/2250/152342.
Texte intégralRésumé :
Tesis para optar al grado de Doctor en Ciencias de la Ingeniería, Mención Modelación Matemática<br>Esta tesis estudia la detección y reconstrucción del término espacial de una fuente de variables separables en problemas de onda acústica y elástica. Para esto, estudiamos el método time-reversal mirror, el cual explota una invariancia intrínseca de la física a nivel microscópico que se observa también a nivel macroscópico en las ecuaciones de ondas. Esto significa que es posible recuperar la condición inicial de una ecuación de ondas homogénea revirtiendo la onda a través del tiempo. Para localizar y reconstruir el término espacial de la fuente, desarrollamos un método llamado source time reversal.
La aplicación subyacente aquí es la detección de fuentes sísmicas en la minería. Es sabido que la actividad minera induce temblores dentro de las minas [50]. Esto se vuelve bastante peligroso si no se toman las precauciones adecuadas. Conocer sobre el origen de las actividades sísmicas puede ser utilizado para reducir el peligro de derrumbes y mejorar la seguridad dentro de las minas.
Este trabajo se divide en tres capítulos; cada uno de ellos constituye un documento autocontenido para ser presentado como artículo. El primer capítulo aborda el problema de reconstrucción de fuente para ondas acústicas. Para esto introducimos el método source time reversal, la cual reconstruye el término espacial de una fuente de la forma f(x)g(t), donde f(x) entrega la forma y g(t) representa la distribución en tiempo de la fuente. Además, presentamos una estimación del error de la reconstrucción para el caso cuando f es una función de cuadrado integrable. Aquí, proponemos un método de regularización para implementar la reconstrucción de la fuente numéricamente. Adicionalmente, analizamos las principales características y limitaciones del método propuesto cuando se aplica a ondas acústicas.
El capítulo dos estudia el problema de reconstrucción de fuente para ondas elásticas. Extendemos el método source time reversal para problemas elásticos. Además, introducimos un nuevo método de regularización para implementar la reconstrucción del término espacial de la fuente numéricamente para grandes volúmenes de datos. El nuevo método de regularización elimina las altas frecuencias presentes en la señal procesada, lo que permite utilizar mallas numéricas más gruesas y reduce el costo computacional. Finalmente, este capítulo presenta diversos experimentos numéricos para probar que el método es válido en el caso elástico.
El último capítulo analiza un problema de reconstrucción de fuente diferente. Aquí consideramos una fuente compuesta por una suma finita de funciones de variable separable, donde cada término temporal de la fuente es una función delta de Dirac actuando a un tiempo diferente. Basado en una propiedad de tiempo reverso, la fuente puede ser localizada observando el desplazamiento y la velocidad de desplazamiento en el problema reverso [31]. Nosotros extendemos esta idea a sistemas de ondas elásticas. Adicionalmente, proponemos un algoritmo para la implementación numérica.<br>CONICYT, CMM - Conicyt PIA AFB170001 y el proyecto GEAGAM
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Pimenta, Aline de Barros. "Os agentes ambientais e a logística reversa dos resíduos sólidos urbanos na cidade de Juiz de Fora - MG." Universidade Federal de Juiz de Fora, 2012. https://repositorio.ufjf.br/jspui/handle/ufjf/1918.
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Previous issue date: 2012-02-27<br>CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior<br>Em função da geração crescente e diversificada de Resíduos Sólidos Urbanos e da implantação de um sistema de gestão inadequado, configura-se o agravamento de problemas ambientais, econômicos e sociais, relacionados tanto à saúde pública, quanto à contaminação do solo e da água. Diante deste contexto urbano, mundialmente reproduzido, apresenta-se como objetivo específico evidenciar a atividade logística reversa informal, realizada pelos catadores, e a sua capacidade de ampliar as possibilidades produtivas da tecnologia reversa e potencializar a redução, reutilização e reciclagem energética e material dos resíduos sólidos produzidos cotidianamente. A fim de avaliar a relação entre os trabalhadores de rua (catadores), o ambiente de trabalho e a qualidade de vida que caracteriza seus hábitos e atuações na cidade de Juiz de Fora, Minas Gerais, foram analisados dados aferidos em 2008 e reiterados em 2010 e 2011, com base em referencial teórico multidisciplinar com o propósito de viabilizar uma análise apurada da realidade da gestão municipal de resíduos sólidos em comparação à realidade nacional. A busca por uma maior eficiência das políticas de gestão dos resíduos sólidos e da integração deste sistema está diretamente relacionada à conscientização de seus geradores e o comprometimento dos diversos setores, públicos e privados. Com a análise do potencial ambiental, econômico e social da redução, reutilização e reciclagem, energética e material, dos resíduos sólidos gerados e coletados na cidade, foi possível inferir que a gestão adequada de resíduos associa-se à maior sustentabilidade das operações de logística reversa e reinserção de bens e materiais ao ciclo produtivo.<br>Due to the growing and diverse generation of urban solid waste and the establishment of an inadequate management system, the environmental, economic and social problems, all related to the public health and the contamination of soil and water, have gotten worse. In the face of this urban context, reproduced worldwide, it is presented as a specific objective to evidence the reverse logistics informal activity, conducted by the garbage collectors, and its ability to expand the productive possibilities of the reverse technology and enhance the energetic and material reduction, reuse and recycling of solid waste produced daily. In order to evaluate the relationship between street workers (garbage collectors), the work environment and the quality of life that characterizes their habits and actions in the city of Juiz de Fora, Minas Gerais, were analyzed measured data in 2008 and repeated in 2010 and 2011, based on a multidisciplinary theoretical reference with the aim of enabling a detailed analysis of the reality of the municipal management of solid waste in comparison to the national reality. The search for a greater efficiency of management policies of solid waste and the integration of this system is directly related to the awareness of their generators and the commitment of several sectors, public and private. By analyzing the environmental, economic and social potential of the reduction, reuse and recycling, energetic and material, of solid waste generated and collected in the city, we could infer that the proper management of waste has been associated to a greater sustainability of the reverse logistics operations and reintegration of goods and materials to the production cycle.
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Radeva, Tsvetomira. "Properties of link reversal algorithms for routing and leader election." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/82398.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2013.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (p. 75-77).<br>We present two link-reversal algorithms and some interesting properties that they satisfy. First, we describe the Partial Reversal (PR) algorithm [13], which ensures that the underlying graph structure is destination-oriented and acyclic. These properties of PR make it useful in routing protocols and algorithms for solving leader election and mutual exclusion. While proofs exist to establish the acyclicity property of PR, they rely on assigning labels to either the nodes or the edges in the graph. In this work we present simpler direct proof of the acyclicity property of partial reversal without using any external or dynamic labeling mechanisms. Second, we describe the leader election (LE) algorithm of [16], which guarantees that a unique leader is elected in an asynchronous network with a dynamically-changing communication topology. The algorithm ensures that, no matter what pattern of topology changes occurs, if topology changes cease, then eventually every connected component contains a unique leader and all nodes have directed paths to that leader. Our contribution includes a complexity analysis of the algorithm showing that after topology changes stop, no more than 0(n) elections occur in the system. We also provide a discussion on certain situations in which a new leader is elected (unnecessarily) when there is already another leader in the same connected component. Finally, we show how the LE algorithm can be augmented in such a way that nodes also have the shortest path to the leader.<br>by Tsvetomira Radeva<br>S.M.
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Dhapare, Sneha. "SALVIANOLIC ACID B FOR PULMONARY DELIVERY TOWARDS REVERSAL OF EMPHYSEMA." VCU Scholars Compass, 2017. http://scholarscompass.vcu.edu/etd/4812.
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A new pathobiologic hypothesis has recently emerged that the alveolar structural destruction and loss in emphysema are caused by the deficiency of vascular endothelial growth factor (VEGF). Therefore, this project hypothesized that such pathobiologic VEGF deficiency of emphysematous lungs can be recovered with a natural caffeic acid tetramer, salvianolic acid B (SalB), through activation of signal transducer and activator of transcription 3 (STAT3), so that emphysema can be reversed as a result of inhibition of induced cell death, stimulation of cell proliferation and migration, and promotion of stem cell recruitment to the lungs.
SalB was first shown to be potently anti-oxidative (IC50 = 3.7 μM), but devoid of anti-elastase activity. SalB was then administered to the lungs of healthy rats at 0.2 mg/kg for two weeks, verifying ~1.7-fold increased lung tissue expressions of phosphorylated STAT3 (pSTAT3; an activated form of STAT3) and VEGF. Subsequently, SalB was examined in the anti-cell death assay, cell proliferation and migration assays, and trans-
endothelial stem cell recruitment assay in the in vitro lung epithelial (A549) and endothelial (HMVEC-L) cell systems. SalB at 25 μM exerted significant 48-88 % inhibitory activities against cell death induced with oxidative stress and VEGF receptor blockade (with SU5416) in both cell systems, measured by the trypan blue exclusion and propidium iodide-based flow cytometry assays. SalB at 25 μM also stimulated A549 and HMVEC-L cell proliferation by ~1.4-fold and promoted cell migration by ~1.6-fold, while recovering stem cell recruitment impaired with SU5416 by 60 %. The anti-cell death, and proliferation and migration stimulatory activities of SalB were significantly opposed by pharmacological inhibitors of JAK2 (Janus kinase 2; an upper signal of STAT3), STAT3 and VEGF.
SalB was then examined for its in vivo reversal activities in emphysema induced with porcine pancreatic elastase (PPE) and cigarette smoke extract (CSE) in rats. Upon establishment of emphysema on day 21, SalB was administered to the lungs three times weekly over three weeks. SalB at 0.2 mg/kg significantly recovered ~85 %-impaired treadmill exercise endurance by 57-82 %; and reduced abnormal airspace enlargement by 59-75 %. In the PPE-induced emphysematous rats, SalB also reduced the 4-fold greater alveolar destruction index by 61 %. The lung tissue protein expression by Western blot analysis found that cleaved caspase 3 (cell apoptotic marker) was induced by 13-fold, and VEGF was reduced by 60 % in the PPE -induced emphysematous rats. However, pulmonary treatment with SalB at 0.2 mg/kg normalized these proteins, and also significantly increased the expression of a cell proliferation marker, proliferative cell nuclear antigen (PCNA) by 2.6-fold. Note however that SalB treatment did not reduce the neutrophilic myeloperoxidase activity in the lungs induced in the PPE-induced rats. Taken all together, this study has demonstrated that SalB potently inhibited lung cell death, stimulates lung cell proliferation and migration, and restores stem cell migration with its mechanism of STAT3 activation and VEGF elevation and reversed established emphysema in rat models.
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Friesen, Dwight. "Full circle and reversal Thomas C. Oden's Agenda for theology /." Theological Research Exchange Network (TREN), 2002. http://www.tren.com.
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Denison, Michael Hunter. "Image Source Modeling of Time Reversal for Room Acoustics Applications." BYU ScholarsArchive, 2018. https://scholarsarchive.byu.edu/etd/7449.
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Time Reversal (TR) is a technique that may be used to focus an acoustic signal at a particular point in space. While many variables contribute to the quality of TR focusing of sound in a particular room, the most important have been shown to be the number of sound sources, signal bandwidth and absorption properties of the medium [Ribay et al., J. Acoust. Soc. Am. 117(5), 2866-2872 (2005)]. However, the effect of room size on TR focusing has not been explored. Using the image source method algorithm proposed by Allen and Berkley [J. Allen and D. A. Berkley, J. Acoust. Soc. Am. 65(4), 943-950 (1979)], TR focusing was simulated in a variety of rooms with different absorption and volume properties. Experiments are also conducted in a couple rooms to verify the simulations. The maximum focal amplitude, the temporal focus quality, and the spatial focus clarity are defined and calculated for each simulation. The results are used to determine the effects of absorption and room volume on TR. Less absorption increases the amplitude of the focusing and spatial clarity while decreasing temporal quality. Dissimilarly, larger volumes decrease focal amplitude and spatial clarity while increasing temporal quality. This thesis also explores the placement of individual transducers within a room. It also compares the layout of several source transducers used for a reciprocal time reversal process. Maximum focal amplitude and spatial clarity are found to increase when the focus location is dual coplanar to the source location while temporal quality is found to decrease in comparison to the case when source and focal location share only one plane. Maximum focal amplitude is found to be at a minimum when the focus location is at the critical distance and increases closer and farther away from the source, while temporal quality steadily decreases and spatial clarity steadily increases farther from the source. The maximum focal amplitude and the temporal quality are not greatly affected by the type of array layout, but a circular array is ideal for maximizing spatial clarity.
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Trung, Kien-Nguyen [Verfasser]. "Time reversal transmission approach for ultra wideband communications / Trung Kien Nguyen." Hannover : Technische Informationsbibliothek und Universitätsbibliothek Hannover (TIB), 2011. http://d-nb.info/1017987165/34.
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Oksa, Annishka Education Faculty of Arts & Social Sciences UNSW. "Expertise reversal effect in explanatory notes for readers of Shakespearean text." Awarded by:University of New South Wales. Education, 2009. http://handle.unsw.edu.au/1959.4/43747.
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In recent decades, research into human cognition has unveiled in-depth insights into the structures and processes involved in the encoding, storage and retrieval of information. As human working memory is limited in both duration and capacity, cognitive load theory (Sweller, 1988, 1989, 1993, 1994; Sweller & Chandler 1994; Chandler & Sweller 1991; 1996) asserts that information should be designed in a way that does not mentally overload learners. However, instructional designs rarely take into account cognitive processes when structuring teaching materials. In fact, many traditional forms of instruction were devised prior to fundamental research into cognitive load effects. As a result, learners are often subjected to cognitive overload when required to engage in extraneous tasks that are not directly related to meaningful learning. This is a particular problem for intrinsically complex Shakespearean works, renowned to be some of the most difficult texts students may ever encounter. Acknowledging that Shakespearean texts were written for performance, they are not always studied as such. Frequently, the texts are read around the class, whereby the focus is not dramatic but literary. Therefore, under the current system of study it is necessary to investigate instruction for reading comprehension of Shakespearean texts. Reading Shakespeare's plays will often overwhelm working memory resources and cause comprehension problems due to the many interactive elements of information readers are required to process simultaneously. This is a significant issue as Shakespeare's works hold a great deal of literary, dramatic, and linguistic significance and their study forms a compulsory part of school curriculum and assessment that affects all students from English speaking nations. By tradition conventional modes of instruction for Shakespearean texts require readers to consult disparate sources of information such as footnotes and endnotes that may contain either inadequate or unnecessary detail. Having to search for relevant information and mentally integrate separate sources of text results in a split attention effect and causes high levels of unnecessary cognitive load. As a result, Shakespeare's texts continue to be such a struggle for many students that some educational faculties have started to initiate the removal of Shakespeare from curriculum instead of developing more effective instructional methods for this domain. This study applies cognitive load theory as a means of investigating the comprehension of Shakespeare by testing the effects of explanatory notes integrated line by line with original Shakespearean verse. Previous studies in cognitive load theory have indicated that restructuring material in accordance with cognitive principles can optimise learning. However, the majority of these studies have focused on technical areas.
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Nguyen, Linh V., and Leonid A. Kunyansky. "A Dissipative Time Reversal Technique for Photoacoustic Tomography in a Cavity." SIAM PUBLICATIONS, 2016. http://hdl.handle.net/10150/622000.
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We consider the inverse source problem arising in thermo-and photoacoustic tomography. It consists in reconstructing the initial pressure from the boundary measurements of the acoustic wave. Our goal is to extend versatile time reversal techniques to the case when the boundary of the domain is perfectly reflecting, effectively turning the domain into a reverberant cavity. Standard time reversal works only if the solution of the direct problem decays in time, which does not happen in the setup we consider. We thus propose a novel time reversal technique with a nonstandard boundary condition. The error induced by this time reversal technique satisfies the wave equation with a dissipative boundary condition and, therefore, decays in time. For larger measurement times, this method yields a close approximation; for smaller times, the first approximation can be iteratively refined, resulting in a convergent Neumann series for the approximation.
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Lear, Jeremy M. "Polarity-Reversal Cascades for the Coupling of Radicals with Unsaturated Systems." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1562958629394222.
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Sit, Hui-ping Cindy. "Motivational orientations and sport participation in youth : a comparison of achievement goal theory and reversal theory /." Hong Kong : University of Hong Kong, 2002. http://sunzi.lib.hku.hk/hkuto/record.jsp?B24873056.
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Henning, Ellen Marie. "A parent-mediated habit reversal intervention for chronic tic disorders in children." Diss., University of Iowa, 2017. https://ir.uiowa.edu/etd/5774.
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Chronic tic disorders (CTDs), including Tourette’s disorder and persistent motor or vocal tic disorder, are neurobiological conditions affecting an estimated 3 to 4 percent of children and adolescents. These disorders include the presence of motor and/or phonic tics, which can range in number, frequency, and severity. Although CTDs are typically treated through medications, the available medications have the potential of adverse side effects, do not result in long-term coping strategies, and may not be effective or preferable for all individuals. Habit reversal training (HRT), a behavioral intervention for tics, has been identified as a well-established treatment. The purpose of habit reversal is to build an individual’s awareness of his or her tics and disrupt tics through developing a competing behavioral response.
One avenue or service delivery that has not yet been explored for individuals with CTDs is use of a parent-mediated approach to habit reversal. Parent-mediated interventions have been used successfully with children with challenging behavior and autism. They are based on a triadic model, in which a therapist works directly with a parent to teach the therapeutic techniques. Parents, in turn, work directly with their children while receiving feedback from the therapist.
The current study investigated a parent-mediated habit reversal intervention for the treatment of chronic tic disorders in two children. A delayed multiple baseline design was used. Baseline data were collected for three sessions. Intervention was delivered over six sessions, during which time coaching was faded. Follow up data collection occurred one month after the end of treatment. Based on changes in parental fidelity of implementation from baseline to intervention, this study provides preliminary evidence for parents being trained as therapists and providing habit reversal training strategies to their children. This treatment was reported as acceptable by both parent participants and by one of the child participants. Treatment motivation remained high and stable throughout baseline, intervention, and follow up. Child motivation was more variable during baseline, intervention, and follow up. Tic severity was also variable and more research would be needed to determine the impact of treatment for tics. Limitations and implications for future research are provided.
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McAdam, Ian. "Connectionist models for reverse engineering." Thesis, McGill University, 1993. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=67543.
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Design recovery, a part of the reverse engineering process of a program, must supply a programmer with all the information they need to fully understand a program or a system. In this thesis, a connectionist method is proposed for analyzing the informal information (comments and mnemonics) in a program that can be used for design recovery in conjunction with more traditional approaches. A connectionist model was chosen because of its properties of being robust (capable of tolerating noisy inputs), its associative memory ability (capable of retrieving a concept given only the context of the original input word), and its generalization ability (learn conceptually relevant micro-features of the domain). The proposed approach uses a combination of top down domain analysis (the creation of a concept hierarchy by a domain expert, to be used in the formation of the training set) and a bottom up approach (the analysis of the informal information using the network).
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Yavuz, Mehmet Emre. "Time reversal based signal processing techniques for ultrawideband electromagnetic sensing in random media." Columbus, Ohio : Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1198770526.
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Fouda, Ahmed Elsayed. "Electromagnetic Time-Reversal Imaging and Tracking Techniques for Inverse Scattering and Wireless Communications." The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1366202740.
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Hurford, William E. "Sugammadex vs. neostigmine/glycopyrrolate for routine reversal of rocuronium block in adult patients." University of Cincinnati / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1573224876100739.
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Hughes, Nina(Nina Yuchen). "Reverse logistics supply chain process modeling and simulation." Thesis, Massachusetts Institute of Technology, 2019. https://hdl.handle.net/1721.1/122581.
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Thesis: M.B.A., Massachusetts Institute of Technology, Sloan School of Management, 2019, In conjunction with the Leaders for Global Operations Program at MIT<br>Thesis: S.M., Massachusetts Institute of Technology, Department of Civil and Environmental Engineering, 2019, In conjunction with the Leaders for Global Operations Program at MIT<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (page 67).<br>As consumer preferences shift towards online shopping and utilizing their homes as fitting rooms, traditional brick and mortar retailers are faced with the challenge to adapt. Many retailers are experiencing a growing number of returned merchandize, many of which cannot be easily resold to consumers due to various supply chain challenges. This thesis explores the opportunities to improve the consumer returns process and presents methods for modeling the supply chain process for reverse logistics in the retail industry derived from case studies. The model then allows for hypothesis testing. By changing parameters in the model, this thesis further explores the scenarios in which the supply chain process may be improved to increase margin and decrease cost. The primary recommendations include specific modifications to the current reverse supply chain flow, enabling new channels that improve speed and margin, as well as developing the decision tool further for better accuracy and integration into the supply chain.<br>by Nina Hughes.<br>M.B.A.<br>S.M.<br>M.B.A. Massachusetts Institute of Technology, Sloan School of Management<br>S.M. Massachusetts Institute of Technology, Department of Civil and Environmental Engineering
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Kepplinger, Jessica, Kristian Barlinn, Stanislava Kolieskova, et al. "Reversal of the neurological deficit in acute stroke with the signal of efficacy trial of auto-BPAP to limit damage from suspected sleep apnea (Reverse-STEAL): study protocol for a randomized controlled trial." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-127301.
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Background: Although the negative impact of sleep apnea on the clinical course of acute ischemic stroke (AIS) is well known, data regarding non-invasive ventilation in acute patients are scarce. Several studies have shown its tolerability and safety, yet no controlled randomized sequential phase studies exist that aim to establish the efficacy of early non-invasive ventilation in AIS patients.
Methods/design: We decided to examine our hypothesis that early non-invasive ventilation with auto-titrating bilevel positive airway pressure (auto-BPAP) positively affects short-term clinical outcomes in AIS patients. We perform a multicenter, prospective, randomized, controlled, third rater- blinded, parallel-group trial. Patients with AIS with proximal arterial obstruction and clinically suspected sleep apnea will be randomized to standard stroke care alone or standard stroke care plus auto-BPAP. Auto-BPAP will be initiated within 24 hours of stroke onset and performed for a maximum of 48 hours during diurnal and nocturnal sleep. Patients will undergo unattended cardiorespiratory polygraphy between days three and five to assess sleep apnea. Our primary endpoint will be any early neurological improvement on the NIHSS at 72 hours from randomization. Safety, tolerability, short-term and three-months functional outcomes will be assessed as secondary endpoints by un-blinded and blinded observers respectively.
Discussion: We expect that this study will advance our understanding of how early treatment with non-invasive ventilation can counterbalance, or possibly reverse, the deleterious effects of sleep apnea in the acute phase of ischemic stroke. The study will provide preliminary data to power a subsequent phase III study.
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Kepplinger, Jessica, Kristian Barlinn, Stanislava Kolieskova, et al. "Reversal of the neurological deficit in acute stroke with the signal of efficacy trial of auto-BPAP to limit damage from suspected sleep apnea (Reverse-STEAL): study protocol for a randomized controlled trial." BioMed Central, 2013. https://tud.qucosa.de/id/qucosa%3A27295.
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Background: Although the negative impact of sleep apnea on the clinical course of acute ischemic stroke (AIS) is well known, data regarding non-invasive ventilation in acute patients are scarce. Several studies have shown its tolerability and safety, yet no controlled randomized sequential phase studies exist that aim to establish the efficacy of early non-invasive ventilation in AIS patients.
Methods/design: We decided to examine our hypothesis that early non-invasive ventilation with auto-titrating bilevel positive airway pressure (auto-BPAP) positively affects short-term clinical outcomes in AIS patients. We perform a multicenter, prospective, randomized, controlled, third rater- blinded, parallel-group trial. Patients with AIS with proximal arterial obstruction and clinically suspected sleep apnea will be randomized to standard stroke care alone or standard stroke care plus auto-BPAP. Auto-BPAP will be initiated within 24 hours of stroke onset and performed for a maximum of 48 hours during diurnal and nocturnal sleep. Patients will undergo unattended cardiorespiratory polygraphy between days three and five to assess sleep apnea. Our primary endpoint will be any early neurological improvement on the NIHSS at 72 hours from randomization. Safety, tolerability, short-term and three-months functional outcomes will be assessed as secondary endpoints by un-blinded and blinded observers respectively.
Discussion: We expect that this study will advance our understanding of how early treatment with non-invasive ventilation can counterbalance, or possibly reverse, the deleterious effects of sleep apnea in the acute phase of ischemic stroke. The study will provide preliminary data to power a subsequent phase III study.
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Boyle, Casey Alex. "Process enablers for successful reverse engineering inside large organizations." Thesis, Massachusetts Institute of Technology, 2020. https://hdl.handle.net/1721.1/126949.
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Thesis: M.B.A., Massachusetts Institute of Technology, Sloan School of Management, in conjunction with the Leaders for Global Operations Program at MIT, May, 2020<br>Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, in conjunction with the Leaders for Global Operations Program at MIT, May, 2020<br>"May 2020." Cataloged from the official PDF of thesis.<br>Includes bibliographical references (pages 131-135).<br>Reverse engineering has the potential to be a strategic advantage for many engineering companies. As companies continuously look for new ways to improve their business and technical expertise, reverse engineering facilitates detailed knowledge capture for many possible applications. These applications open new channels of revenue, create more options in the market, and drive value to customers. Although reverse engineering is nothing new to industry and has been actively researched, this thesis seeks to understand the key enablers that promote successful reverse engineering at scale in a modern corporation. Given that many large firms are set up with the forward engineering process in mind, what are the differentiated characteristics of an effective reverse engineering organization? By treating reverse engineering as a system of interconnected dependent events, an organization can be shaped to build a workflow with the necessary linkages for successful execution and scaling.<br>This "pull" more than "push" process that establishes clear communication between functions is key to preventing rework, shortening flow time, and increasing quality. Reverse engineering, like traditional forward engineering, must be organized as an integrated multifunctional process with organized information sharing, compromise, and iteration. Additionally, the teardown process itself is a central piece of the puzzle for successful reverse engineering. This is due to the multiple strategic linkages associated and interconnectedness required by key stakeholders for understanding the investigated component. A teardown is defined as an observant disassembly of a component for information gain. This thesis focuses more deeply into the teardown process. By showcasing challenges that lead to common errors, teardown process recommendations are made for a more efficient way to reverse engineer.<br>A lack of early stakeholder engagement prior to teardown frequently leads to inefficient knowledge sharing. More active stakeholder participation is recommended to improve the overall quality of teardown reports and serve as an additional opportunity to discover a component's hidden complexities. It is also recommended that formal design tools, such as functional analysis, be utilized for truly understanding a component's physical behavior. Implementing these recommendations and tools will increase the efficiency and output quality of reverse engineering teams, reducing rework.<br>by Casey Alex Boyle.<br>M.B.A.<br>S.M.<br>M.B.A. Massachusetts Institute of Technology, Sloan School of Management<br>S.M. Massachusetts Institute of Technology, Department of Mechanical Engineering
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Smith, Wendy. "A study of the relationship between reversals and several factors in the grade 2 learner." Pretoria : [s.n.], 2009. http://upetd.up.ac.za/thesis/available/etd-10142009-174408/.
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Ashraf, Syeda Nishat. "Applicability of coagulation technologies for high-turbidity coal seam gas water treatment." Thesis, Queensland University of Technology, 2019. https://eprints.qut.edu.au/127500/1/Syeda_Ashraf_Thesis.pdf.
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This project developed new strategies to facilitate reuse of water from the coal seam gas (CSG) industry. Both chemical coagulation and electrocoagulation were examined for their ability to protect downstream reverse osmosis (RO) desalination systems from detrimental fouling and scaling. Electrocoagulation in particular was highly effective at removing dissolved silicates, alkaline earth ions and suspended solids; thus RO operation was expected to be improved. In addition the purification of resultant brine was demonstrated, thus potentially enabling the recovery of salt as a product. It was recommended to scale-up electrocoagulation testing to pilot plant.
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Liu, Xiaodong. "Abstraction : a notion for reverse engineering." Thesis, De Montfort University, 1999. http://hdl.handle.net/2086/4214.
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Sit, Eric N. 1977. "Reverse HTTP tunneling for firewall traversal." Thesis, Massachusetts Institute of Technology, 2000. http://hdl.handle.net/1721.1/9086.
Texte intégralRésumé :
Thesis (S.B. and M.Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2000.<br>Includes bibliographical references (leaf 104).<br>This thesis describes a reverse hypertext tunneling protocol that allows a web browser from outside a firewall to access a web server inside a firewall. Reverse HTTP utilizes pre-existing proxy services to create a transparent and scalable method to tunnel through a firewall. Reverse HTTP provides an excellent solution to the problem of providing controlled access to firewall protected resources. This is because unlike traditional firewall traversal methods, reverse HTTP is completely software based and requires no changes to the existing firewall configuration. Reverse HTTP works because it tunnels traffic in a form which a web proxy server on the firewall allows to pass. A Java software implementation has been developed and tested to demonstrate the usefulness and efficacy of the reverse HTTP protocol. This experimental implementation proves that a portable, scalable solution can be developed with comparable performance characteristics to a normal web proxy. Although the implementation can be used to view protected web sites, it does not compromise the overall network security.<br>by Eric N. Sit.<br>S.B.and M.Eng.
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Clason, Christian. "A direct method for the numerical time reversal of waves in a heterogeneous medium." [S.l.] : [s.n.], 2006. http://mediatum2.ub.tum.de/doc/541465/document.pdf.
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Schmidt, Bruno Eugen [Verfasser]. "White light filamentation : tailoring & application for charge reversal of Ag3 / Bruno Eugen Schmidt." Berlin : Freie Universität Berlin, 2008. http://d-nb.info/1023371944/34.
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Harrison, Rachel. "Micronutrient Treatment for Adolescents with Severe Mood Dysregulation: A Single-Case Reversal Design Analysis." Thesis, University of Canterbury. Psychology, 2011. http://hdl.handle.net/10092/6572.
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Research has examined the effects of micronutrients on mood in both healthy and psychiatric populations. EMPowerplus (EMP+) is a formula containing a wide range of vitamins and minerals. It has been examined for the treatment of mood instability, anxiety, Attention Deficit Hyperactivity Disorder (ADHD) and autism. The present study trialled EMP+ with five adolescents, aged 16-21, all with Severe Mood Dysregulation (SMD) as well as co-occuring psychiatric diagnoses i.e. ADHD, anxiety and substance abuse. The sample reflects a group of adolescents with complex psychiatric presentations and therefore difficult to treat. An ABAB (off-on-off-on) research design was employed. An open-label trial (8 weeks) of the micronutrients was followed by a withdrawal phase (8 weeks) and then a reinstatement of the micronutrients for a longer period of time (up to 24 weeks). There were in-depth pre and post assessments and on-going monitoring of the participants for the duration of the study. Clinically significant improvements in symptoms and functioning were demonstrated in three/four participants. Two participants demonstrated on-off control of psychiatric symptoms, with a reversal and replication of treatment effect. Further, one participant demonstrated clinically significant improvements in mood and functioning while on the micronutrients; however, he was lost to follow up following the 7.1 earthquake, and a reversal was not obtained. One participant demonstrated a trend toward improvements in mood while on the micronutrients and subsequent deterioration during the wash-out phase. However, she decided to withdraw from the study at four weeks off to go on psychiatric medication. Further, one participant demonstrated a variable response. This study provides some further evidence that micronutrients may be an effective treatment for psychiatric symptoms, consistent with other reports. Further research, such as randomised clinical trials and studies investigating the mechanisms of action, appears warranted.
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Le, Hénaff Anne-Claire. "Time-variant solar-powered electrodialysis reversal desalination for affordable off-grid clean water supply." Thesis, Massachusetts Institute of Technology, 2019. https://hdl.handle.net/1721.1/132744.
Texte intégralRésumé :
Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, September, 2019<br>Cataloged from the PDF version of thesis.<br>Includes bibliographical references (pages 91-96).<br>The goal of this research is to design affordable photovoltaic-powered electrodialysis reversal systems capable of desalinating brackish water in remote locations of developing countries, and thereby increase the availability of freshwater in water-stressed areas such as rural India. At the village scale, electrodialysis technology for brackish groundwater desalination has the potential to substantially reduce water wastage and energy consumption compared to on-grid reverse osmosis (RO) plants currently commercialized. Moreover, PV-powered systems can supply water in off-grid locations where on-grid systems cannot be installed, at no environmental cost. However, the levelized cost of water achieved by state-of-the-art PV-EDR systems is still prohibitively high for cost-constrained communities, due to the large battery capacity required to reshape the solar power profile and accommodate the inflexible power profile of the desalination load in constant operation. To reduce water cost, a novel, flexible operational strategy for PV-EDR systems is presented and experimentally validated on a full-scale pilot. By actively controlling voltage and flow rate with a dedicated hardware and software architecture, the ED power consumption is matched to the available solar power at any time. The experimental fraction of solar energy directly used reached 76%, which is 91% higher than in the constant operation case, where the PV-EDR system runs at constant voltage and flow rate. As a result, the experimental system dynamically adapted its desalination rate to the solar irradiance profile, producing freshwater in synchronization with the sun while reducing the need for batteries by 92% on average compared to the conventional operation. Because desalination efficiency decreases as a function of operating power, it is suggested that a small battery capacity would allow reshaping the direct solar power profile into a more suitable profile for water production. If optimally managed, a 3 kWh battery addition on the experimental setup is predicted to increase water production by 25%. A machine-learning-based algorithm was designed to predict the optimal battery management strategy online and is demonstrated in simulation to achieve over 99% of the ideal water production. Shifting from constant to flexible operation is expected to reduce the levelized cost of water by 22% compared to current state-of-the-art PV-EDR systems. This number was obtained by optimizing the flexible PV-EDR system design to minimize levelized cost of water (LCOW) while answering daily demand for one year for a case study village location in Chelluru, India. Most importantly, the optimal flexible PV-EDR system is shown to be cost-competitive with current on-grid community-scale RO desalination solutions in India. Cost projections for ED membrane and brine disposal show that in the future, PV-EDR could produce water at 60% of the cost of water produced with on-grid RO.<br>by Anne-Claire Le Hénaff.<br>S.M.<br>S.M. Massachusetts Institute of Technology, Department of Mechanical Engineering
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Sale, Kenneth E. "⁷Li(p,p)⁷Li scattering observables as a test for time reversal invariance violation /." The Ohio State University, 1985. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487260859496123.
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Drikas, Zachary Benjamin. "New Techniques for Time-Reversal-Based Ultra-wideband Microwave Pulse Compression in Reverberant Cavities." Diss., Virginia Tech, 2020. http://hdl.handle.net/10919/100998.
Texte intégralRésumé :
Generation of high-peak power, microwave ultra-short pulses (USPs) is desirable for ultra-wideband communications and remote sensing. A variety of microwave USP generators exist today, or are described in the literature, and have benefits and limitations depending on application. A new class of pulse compressors for generating USPs using electromagnetic time reversal (TR) techniques have been developed in the last decade, and are the topic of this dissertation. This dissertation presents a compact TR microwave pulse-compression cavity that has ultra-wide bandwidth (5 GHz – 18 GHz), and employs waveguide feeds for high-peak power output over the entire band. The system uses a time-reversal-based pulse compression scheme with one-bit processing (OBTR) to achieve high compression gain. Results from full-wave simulations are presented as well as measurements showing compression gain exceeding 21.2 dB, 22% efficiency, and measured instantaneous peak output powers reaching 39.2 kW. These are all record results for this type of pulse compressor. Additionally presented is new analysis of variation in compression gain due to impulse response recording time and bandwidth variation, new experimental work on the effect of mode stirrer position on compression gain, and a novel RF switch-based technique for reducing time-sidelobes while using OBTR. Finally, a new technique is presented that uses a reverberant cavity with only one feed connected to an ultra-wideband circulator (6.5 GHz to 17 GHz) to perform TRPC. Prior to this work, TRPC has only been demonstrated in electromagnetics using two or more feeds and a reverberant cavity acting as the time-reversal mirror. This new 1-port technique is demonstrated in both simulation and measurement. The proposed system achieves up to a measured 3 dB increase in compression gain and increased efficiency. Also, a novel application of the random coupling model (RCM) to calculate compression gain is presented. The cavity eigenfrequencies are modeled after eigenvalues of random matrices satisfying the Gaussian orthogonal ensembles (GOE) condition. Cavity transfer functions are generated using Monte Carlo simulations, and used to compute the compression gains for many different cavity realizations.<br>Doctor of Philosophy<br>Generation of high-peak power, microwave ultra-short pulses (USPs) is desirable for ultra-wideband communications and remote sensing. A variety of microwave USP generators exist today, or are described in the literature, and have benefits and limitations depending on application. A new class of pulse compressors for generating USPs using electromagnetic time reversal (TR) techniques have been developed in the last decade, and are the topic of this dissertation. This dissertation presents a compact TR-based microwave pulse-compression cavity that has unique features that make it optimal for high-power operations, with results from simulations as well as measurements showing improved performance over other similar cavities published in the literature with a record demonstrated peak output power of 39.2 kW. Additionally, new analysis on the operation and optimization of this cavity for increased performance is also presented. Finally, a new technique is presented that uses a cavity with only one feed that acts as both the input and output. This 1-port technique is demonstrated in both simulation and measurement. The proposed system achieves a two-times increase in compression gain over its 2-port counterpart. In conjunction with these measurements and simulations, a novel technique for predicting the performance of these cavities using Monte Carlo simulation is also presented.
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Curry, Zachary. "Targeting monoacylglycerol lipase for the reversal and prevention of paclitaxel-induced allodynia in mice." VCU Scholars Compass, 2018. https://scholarscompass.vcu.edu/etd/5274.
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Chemotherapy-induced peripheral neuropathy (CIPN) is a side-effect of chemotherapy causing pain in the hands and feet. In particular, paclitaxel causes CIPN lasting for years without effective treatment. There is a strong need for analgesics to both treat and prevent CIPN. One system containing multiple targets to treat CIPN is the endogenous cannabinoid system. This system consists of cannabinoid type 1 (CB1) and type 2 (CB2) receptors primarily expressed on presynaptic neurons and cells of the immune system, respectively. Inhibition of monoacylglycerol lipase (MAGL), which hydrolyzes the endogenous cannabinoid 2- arachidonoylglycerol (2-AG), with JZL184 or MJN110 produces antinociceptive and anti- inflammatory effects in rodent pain models. In this dissertation, we test the hypothesis that MAGL inhibitors will both reverse and prevent mouse paclitaxel-induced mechanical allodynia. JZL184 and MJN110 reversed paclitaxel allodynia in dose-dependent manners with ED50 values (95% C.L.) of 8.4 (5.2-13.6) and 1.8 (1.0-3.3) mg/kg. Using genetic and pharmacologic approaches, we demonstrate that the anti-allodynic effects of both inhibitors require both cannabinoid receptors. As CIPN treatment could require repeated dosing, we demonstrate that repeated administration of 4 mg/kg JZL184 for six days produces anti-allodynic effects in contrast to tolerance development after repeated treatment with 40 mg/kg. We also show that MJN110 attenuates paclitaxel-induced inflammation in the spinal cord and dorsal root ganglia (DRG), namely monocyte chemoattractant protein-1 (MCP-1, CCL2) and phosphorylated p38 MAPK (phospho-p38) expression. Using the conditioned place preference (CPP) paradigm, we demonstrate that MJN110 produces a CPP in paclitaxel-treated, but not in control mice. As CIPN develops during chemotherapy, we also show that JZL184 does not interfere with the anti- proliferative and anti-apoptotic effects of paclitaxel in A549 or H460 lung cancer cell lines. Lastly, we show that co-administration of MAGL inhibitors with paclitaxel prevents the development of allodynia. Co-treatment with 5 mg/kg MJN110 or 40 mg/kg JZL184 prevents allodynia up to one or two week(s), respectively, after paclitaxel cessation. Treatment with 40 mg/kg JZL184 prevents allodynia in both CB1 (+/+) and (-/-) mice, suggesting that prevention is CB1-independent. Taken together, these results suggest that MAGL is a viable target for both the treatment and prevention of paclitaxel-induced allodynia in mice.
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Young, Sarah Marie. "Implementation and Optimization of Time Reversal for Use in Nondestructive Evaluation of Stress Corrosion Cracking." BYU ScholarsArchive, 2018. https://scholarsarchive.byu.edu/etd/7539.
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The time reversal (TR) process manipulates a system's impulse response in order to focus a peak of acoustic energy at a specific location in space and time. This technique has been implemented in both fluid and solid media for purposes ranging from communications to source localization. This thesis will examine both the implementation and processing of TR for nondestructive evaluation in steel, specializing in nonlinear detection methods. A series of steel samples are inspected for stress corrosion cracking (SCC) using TR focusing to excite nonlinearities inherent in cracks. It is determined that SCC exists in the expected regions of the steel samples and that an induced increase in SCC corresponds to an increase in detected nonlinearity. In addition to this, a study is shown wherein TR signal processing is optimized for the detection of cracks. The TR impulse response is modified in a number of ways with the primary goal of increasing the amplitude of the TR focus. Each of these modifications is experimentally scrutinized for characteristics necessary for application to nondestructive evaluation, and ultimately one is chosen that amplifies TR focusing without increasing system nonlinearity. The optimized technique, decay compensation TR, is employed in the detection of SCC and is found to be as or perhaps even more successful than typical TR nondestructive evaluation methods.
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Poist, Jennifer, Regina Wu, Lourdes Peralta, and Marion Slack. "Prescriber Knowledge and Perception of Naloxone Use for Opioid Overdose Reversal among Intravenous Drug Users." The University of Arizona, 2015. http://hdl.handle.net/10150/614097.
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Class of 2015 Abstract<br>Objectives: Evaluate prescriber knowledge on naloxone use for opioid overdose reversals in intravenous drug users. Interview prescribers on their perceptions about intravenous drug users, syringe access programs, and other related topics.
Subjects: Prescribers and medical professionals in the State of Arizona.
Methods: Medical facilities were contacted by email, fax, or telephone requesting for prescribers to complete the survey and return by email or fax, or call to schedule a face-to-face appointment. The respondents of the survey were kept anonymous and were permitted to answer the survey in free text. Surveys were sent to the 68 selected medical facilities at least twice during the study period.
Results: All of the six respondents were male, of the respondents had at least 11 years experience, with two having >30 years. A majority practiced in rehab centers or worked with drug abuse patients, however the number of patients treated per week by respondent varies from 10-320. Also of note five of the six respondents had a family member or relative with an addiction to opioids. The respondents seem to be in support of a naloxone distribution program however it is difficult to draw any conclusions since the number of responses was low.
Conclusions: It appears that prescribers have a favorable perception of naloxone use and support harm reduction strategies, however response rate was too low to make any definitive conclusions.
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Sit, Hui-ping Cindy, and 薛慧萍. "Motivational orientations and sport participation in youth: a comparison of achievement goal theory and reversal theory." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2002. http://hub.hku.hk/bib/B24873056.
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Davalos, Soria Diana Evening, and Chiyón María Arantxa Mares. "Profilaxis preexposición y desarrollo de resistencia a los inhibidores nucleósidos de la transcriptasa reversa: revisión sistemática." Bachelor's thesis, Universidad Peruana de Ciencias Aplicadas (UPC), 2020. http://hdl.handle.net/10757/654716.
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Objetivo: sintetizar la evidencia acerca de la resistencia a inhibidores nucleósidos de la transcriptasa reversa (NRTI) en personas que reciben PrEP.
Métodos: se realizó una revisión sistemática de estudios experimentales. Se incluyeron estudios que comparaban el uso de PrEP frente a placebo o su no uso en población de riesgo para la infección de VIH; siendo el outcome evaluado el desarrollo de resistencia a NRTI. La selección de artículos y la extracción de datos fueron realizadas por dos revisores de manera independiente. Se realizó un metaanálisis de efectos aleatorios tanto de manera total como en subpoblaciones y según el momento de seroconversión. Para valorar el riesgo de sesgo se utilizó herramienta Risk of Bias 2.0 (RoB 2.0). Se usó como referencia el Software Review Manager 5.
Resultados: se incluyeron nueve artículos correspondientes a seis estudios. Se encontró que el uso de PrEP no incrementa el riesgo de resistencia a TDF/FTC en la población total que recibió la intervención, haya o no presentado la infección. Sin embargo, en el grupo que seroconvirtió sí se encontró un mayor riesgo de resistencia en los que usaron PrEP (RR: 2,76; IC95%: 1,22 a 6,26; I2: 0%); el cual correspondía sólo al grupo que tenía infección por VIH latente al momento de iniciar la intervención (RR: 3,91; IC95%: 1,30 a 1,70; I2: 0%).
Conclusiones: el uso de PrEP no incrementa el riesgo de resistencia a TDF/FTC en el total de usuarios, pero sí en pacientes con infección latente por el VIH al enrolamiento.<br>Objective: Synthesize the evidence on the development of nucleoside reverse transcriptase inhibitor (NRTI) resistance in people receiving PrEP for the prevention HIV.
Methods: We conducted a systematic review of experimental studies, we carried-out a search in electronic databases, as well as a gray literature search. We included studies comparing the use of PrEP against placebo or nothing, in the population at risk of HIV infection; the outcome evaluated was the development of NRTI resistance. The selection of articles and the extraction of data were carried out by two reviewers independently. A meta-analysis of random effects was carried-out for the global populations as well as a sub-analysis according to the risk group and the time of seroconversion. We used The Review Manager 5 Software.
Results: We included nine articles corresponding to six studies. We found that the use of PrEP does not increase the risk of resistance to TDF/FTC in the total of population who received the intervention. But, in the group that seroconverted, we found that the use of PrEP increases the risk of resistance (RR: 2,76; IC95%: 1,22 a 6,26; I2: 0%); this risk mainly corresponds to the group that had a latent HIV infection at the time of initiating the intervention (RR: RR: 3,91; IC95%: 1,30 a 1,70, I2: 0%).
Conclusions: The use of PrEP does not increase the risk of resistance to TDF / FTC in the total of PrEP users, but it does in patients with latent HIV infection upon enrollment.<br>Tesis
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Deckman, Cassandra M. "DEPHOSPHORYLATION OF INNER ARM 1 IS REQUIRED FOR CILIARY REVERSALS IN TETRAHYMENA THERMOPHILA." Miami University / OhioLINK, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=miami1054064051.
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Tunggal, Jonathan Kurniadi. "Cell concentration and drug penetration, implications for the reversal of multidrug resistance in solid tumours." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0017/NQ45743.pdf.
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Phillips, Hannah(Hannah Michelle). "A data-driven approach to continuous improvement in reverse logistics." Thesis, Massachusetts Institute of Technology, 2020. https://hdl.handle.net/1721.1/126915.
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Thesis: M.B.A., Massachusetts Institute of Technology, Sloan School of Management, in conjunction with the Leaders for Global Operations Program at MIT, May, 2020<br>Thesis: S.M., Massachusetts Institute of Technology, Department of Civil and Environmental Engineering, in conjunction with the Leaders for Global Operations Program at MIT, May, 2020<br>Cataloged from the official PDF of thesis.<br>Includes bibliographical references (pages 78-79).<br>Verizon may rely on third-party logistics providers (3PLs) to manage some aspects of the reverse supply chain of Fios equipment. As a result, it depends on the 3PL to continually strive for increased quality, reliability, capacity, and speed. Above all, in order to have a successful partnership, the process must be economical for the 3PL. As several sources of variation are detrimental to the 3PL's margins and cause operational problems, Verizon is investing in the supplier relationship to ensure that the 3PL is profitable and positioned for the future. Making sure there is a "win-win" relationship is beneficial for both parties and helps to ensure that the investments that have been made will continue to result in success, including operational improvements. To do this, a culture of continuous improvement and data-driven decisions needs to be cultivated and developed at the 3PL. The goal of this project is two-fold. First, there is a need to understand the variation that exists in the 3PL's process as well as the associated costs, which include overtime, ineffective labor and production planning, and high turnover. The secondary goal of the project is to empower the 3PL to make data-driven decisions in the future and start to shift their culture to one that aligns better with Verizon's. By showing the benefits of collaboration between the two companies, this project will help build trust. In this thesis, we discuss how process mining is used to understand the 3PL's current state and guide data-driven continuous improvement. We introduce several opportunities for handling variation, including creating visibility into return volumes, reducing defects caused by incorrect packaging, and creating feedback mechanisms for operators. This is done in close collaboration with the 3PL to ensure they will ultimately have ownership of implementation.<br>by Hannah Phillips .<br>M.B.A.<br>S.M.<br>M.B.A. Massachusetts Institute of Technology, Sloan School of Management<br>S.M. Massachusetts Institute of Technology, Department of Civil and Environmental Engineering
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Akgul, Tankut. "Assembly Instruction Level Reverse Execution for Debugging." Diss., Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/5249.
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Reverse execution can be defined as a method which recovers the states that a program attains during its execution. Therefore, reverse execution eliminates the need for repetitive program restarts every time a bug location is missed. This potentially shortens debug time considerably.
This thesis presents a new approach which, for the first time ever (to the best of the author's knowledge), achieves reverse execution at the assembly instruction level on general purpose processors via execution of a reverse program. A reverse program almost always regenerates destroyed states rather than restoring them from a record. Furthermore, a reverse program provides assembly instruction by assembly instruction execution in the backward direction. This significantly reduces state saving and thus decreases the associated memory and time costs of reverse execution support.
Furthermore, this thesis presents a new dynamic slicing algorithm that is built on top of assembly instruction level reverse execution. Dynamic slicing is a technique which isolates the code parts that influence an erroneous variable at a program point. The algorithm presented in this thesis achieves dynamic slicing via execution of a reduced reverse program. A reduced reverse program is obtained from a full reverse program by omitting the instructions that recover states irrelevant to the dynamic slice under consideration. This provides a reverse execution capability along a designated dynamic slice only. The use of a reduced reverse program for dynamic slicing removes the need for runtime execution trajectories.
The methodology of this thesis has been implemented on a PowerPC processor with a custom made debugger. As compared to previous work, all of which heavily use state saving techniques, the experimental results show up to 2206X reduction in runtime memory usage, up to 403X reduction in forward execution time overhead and up to 2.32X reduction in forward execution time for the tested benchmarks. Measurements on the selected benchmarks also indicate that the dynamic slicing method presented in this thesis can achieve up to six orders of magnitude (1,928,500X) speedups in reverse execution along the dynamic slice as compared to full-scale reverse execution.
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Hong, I.-Hsuan Ethan. "Decentralized Decision-making for Reverse Production Systems." Diss., Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/14099.
Texte intégralRésumé :
Reverse production systems are often comprised of several tiers with independent members competing at each tier. This research develops and designs a decision-making process for decentralized reverse production systems where each participant in the network determines its decisions in a self-interested way.
This dissertation includes three major parts. The first part develops a prototype model for a decentralized reverse production system with two tiers, collectors and processors, focusing on the coordination of transactions of recycled items between these two tiers. The collectors determine the individual material flow allocation mechanisms, based on predictions of the range of prices from the processors, that relate the flow amount to the overall vector of acquisition prices that will be offered by the processors to all the collectors. The processors compete for the flow from the collectors and reach an equilibrium state where no entity is willing to change its decisions.
In the second part, we extend the prototype model for a general multi-tiered recycling network comprised of the upstream boundary tier, several intermediate tiers, and the downstream boundary tier where each of the tiers has multiple independent entities. Recycled items flow from the top tier to the downstream tier, but acquisition prices are set from the downstream tier back to the upstream tier.
Finally the third part provides a comparison of centralized and decentralized models for reverse production systems and addresses several numerical insights of different system subsidy schemes.