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Littérature scientifique sur le sujet « Fork reversal »

Auteur : Grafiati
Publié le 9 mars 2023
Mis à jour le 10 mars 2023

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Articles de revues sur le sujet "Fork reversal"

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Bhat, Kamakoti P., et David Cortez. « RPA and RAD51 : fork reversal, fork protection, and genome stability ». Nature Structural & ; Molecular Biology 25, no 6 (28 mai 2018) : 446–53. http://dx.doi.org/10.1038/s41594-018-0075-z.

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Fierro-Fernandez, M., P. Hernandez, D. B. Krimer, A. Stasiak et J. B. Schvartzman. « Topological locking restrains replication fork reversal ». Proceedings of the National Academy of Sciences 104, no 5 (22 janvier 2007) : 1500–1505. http://dx.doi.org/10.1073/pnas.0609204104.

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Quinet, Annabel, Delphine Lemaçon et Alessandro Vindigni. « Replication Fork Reversal : Players and Guardians ». Molecular Cell 68, no 5 (décembre 2017) : 830–33. http://dx.doi.org/10.1016/j.molcel.2017.11.022.

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Batenburg, Nicole L., Sofiane Y. Mersaoui, John R. Walker, Yan Coulombe, Ian Hammond-Martel, Hugo Wurtele, Jean-Yves Masson et Xu-Dong Zhu. « Cockayne syndrome group B protein regulates fork restart, fork progression and MRE11-dependent fork degradation in BRCA1/2-deficient cells ». Nucleic Acids Research 49, no 22 (6 décembre 2021) : 12836–54. http://dx.doi.org/10.1093/nar/gkab1173.

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Abstract Cockayne syndrome group B (CSB) protein has been implicated in the repair of a variety of DNA lesions that induce replication stress. However, little is known about its role at stalled replication forks. Here, we report that CSB is recruited to stalled forks in a manner dependent upon its T1031 phosphorylation by CDK. While dispensable for MRE11 association with stalled forks in wild-type cells, CSB is required for further accumulation of MRE11 at stalled forks in BRCA1/2-deficient cells. CSB promotes MRE11-mediated fork degradation in BRCA1/2-deficient cells. CSB possesses an intrinsic ATP-dependent fork reversal activity in vitro, which is activated upon removal of its N-terminal region that is known to autoinhibit CSB’s ATPase domain. CSB functions similarly to fork reversal factors SMARCAL1, ZRANB3 and HLTF to regulate slowdown in fork progression upon exposure to replication stress, indicative of a role of CSB in fork reversal in vivo. Furthermore, CSB not only acts epistatically with MRE11 to facilitate fork restart but also promotes RAD52-mediated break-induced replication repair of double-strand breaks arising from cleavage of stalled forks by MUS81 in BRCA1/2-deficient cells. Loss of CSB exacerbates chemosensitivity in BRCA1/2-deficient cells, underscoring an important role of CSB in the treatment of cancer lacking functional BRCA1/2.
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Liu, W., A. Krishnamoorthy, R. Zhao et D. Cortez. « Two replication fork remodeling pathways generate nuclease substrates for distinct fork protection factors ». Science Advances 6, no 46 (novembre 2020) : eabc3598. http://dx.doi.org/10.1126/sciadv.abc3598.

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Fork reversal is a common response to replication stress, but it generates a DNA end that is susceptible to degradation. Many fork protection factors block degradation, but how they work remains unclear. Here, we find that 53BP1 protects forks from DNA2-mediated degradation in a cell type–specific manner. Fork protection by 53BP1 reduces S-phase DNA damage and hypersensitivity to replication stress. Unlike BRCA2, FANCD2, and ABRO1 that protect reversed forks generated by SMARCAL1, ZRANB3, and HLTF, 53BP1 protects forks remodeled by FBH1. This property is shared by the fork protection factors FANCA, FANCC, FANCG, BOD1L, and VHL. RAD51 is required to generate the resection substrate in all cases. Unexpectedly, BRCA2 is also required for fork degradation in the FBH1 pathway or when RAD51 activity is partially compromised. We conclude that there are multiple fork protection mechanisms that operate downstream of at least two RAD51-dependent fork remodeling pathways.
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Thakar, Tanay, et George-Lucian Moldovan. « The emerging determinants of replication fork stability ». Nucleic Acids Research 49, no 13 (12 mai 2021) : 7224–38. http://dx.doi.org/10.1093/nar/gkab344.

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Abstract A universal response to replication stress is replication fork reversal, where the nascent complementary DNA strands are annealed to form a protective four-way junction allowing forks to avert DNA damage while replication stress is resolved. However, reversed forks are in turn susceptible to nucleolytic digestion of the regressed nascent DNA arms and rely on dedicated mechanisms to protect their integrity. The most well studied fork protection mechanism involves the BRCA pathway and its ability to catalyze RAD51 nucleofilament formation on the reversed arms of stalled replication forks. Importantly, the inability to prevent the degradation of reversed forks has emerged as a hallmark of BRCA deficiency and underlies genome instability and chemosensitivity in BRCA-deficient cells. In the past decade, multiple factors underlying fork stability have been discovered. These factors either cooperate with the BRCA pathway, operate independently from it to augment fork stability in its absence, or act as enablers of fork degradation. In this review, we examine these novel determinants of fork stability, explore the emergent conceptual underpinnings underlying fork protection, as well as the impact of fork protection on cellular viability and cancer therapy.
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Le Masson, Marie, Zeynep Baharoglu et Bénédicte Michel. « ruvAandruvBmutants specifically impaired for replication fork reversal ». Molecular Microbiology 70, no 2 (octobre 2008) : 537–48. http://dx.doi.org/10.1111/j.1365-2958.2008.06431.x.

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De Septenville, Anne L., Stéphane Duigou, Hasna Boubakri et Bénédicte Michel. « Replication Fork Reversal after Replication–Transcription Collision ». PLoS Genetics 8, no 4 (5 avril 2012) : e1002622. http://dx.doi.org/10.1371/journal.pgen.1002622.

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Krishnamoorthy, Archana, Jessica Jackson, Taha Mohamed, Madison Adolph, Alessandro Vindigni et David Cortez. « RADX prevents genome instability by confining replication fork reversal to stalled forks ». Molecular Cell 81, no 14 (juillet 2021) : 3007–17. http://dx.doi.org/10.1016/j.molcel.2021.05.014.

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Torres, Rubén, Carolina Gándara, Begoña Carrasco, Ignacio Baquedano, Silvia Ayora et Juan C. Alonso. « DisA Limits RecG Activities at Stalled or Reversed Replication Forks ». Cells 10, no 6 (31 mai 2021) : 1357. http://dx.doi.org/10.3390/cells10061357.

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The DNA damage checkpoint protein DisA and the branch migration translocase RecG are implicated in the preservation of genome integrity in reviving haploid Bacillus subtilis spores. DisA synthesizes the essential cyclic 3′, 5′-diadenosine monophosphate (c-di-AMP) second messenger and such synthesis is suppressed upon replication perturbation. In vitro, c-di-AMP synthesis is suppressed when DisA binds DNA structures that mimic stalled or reversed forks (gapped forks or Holliday junctions [HJ]). RecG, which does not form a stable complex with DisA, unwinds branched intermediates, and in the presence of a limiting ATP concentration and HJ DNA, it blocks DisA-mediated c-di-AMP synthesis. DisA pre-bound to a stalled or reversed fork limits RecG-mediated ATP hydrolysis and DNA unwinding, but not if RecG is pre-bound to stalled or reversed forks. We propose that RecG-mediated fork remodeling is a genuine in vivo activity, and that DisA, as a molecular switch, limits RecG-mediated fork reversal and fork restoration. DisA and RecG might provide more time to process perturbed forks, avoiding genome breakage.
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Thèses sur le sujet "Fork reversal"

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Berti, Matteo. « New mechanistic insight into replication fork reversal and restart ». Doctoral thesis, Scuola Normale Superiore, 2013. http://hdl.handle.net/11384/85975.

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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.
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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.

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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.
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.
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O'Donoughue, Nicholas A. « Stochastic Time Reversal for Radar Detection ». Research Showcase @ CMU, 2011. http://repository.cmu.edu/dissertations/178.

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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.
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Hallberg, Jonatan, et 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.

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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.
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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.

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nÃo hÃ
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.
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, à o que exerce maior influÃncia sobre as empresas para a formaÃÃo da cadeia reversa. Jà 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.
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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.

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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.
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.
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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.

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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.

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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.

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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
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
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Walther, Andrea. « Program Reversal Schedules for Single- and Multi-processor Machines ». Doctoral thesis, Technische Universität Dresden, 1999. https://tud.qucosa.de/id/qucosa%3A24113.

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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.
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.
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Livres sur le sujet "Fork reversal"

1

Tokarski, Jan. Schematyczny indeks "a tergo" polskich form wyrazowych. Warszawa : Wydawn. Nauk. PWN, 1993.

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Frelick, Bill. Reversal of fortune : Yugoslavia's refugee crisis since the ethnic Albanian return to Kosovo. Washington, D.C : U.S. Committee for Refugees, 2000.

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V, Sekher T., et Institute for Social and Economic Change., dir. Can career-minded young women reverse gender discrimination ? Bangalore : Institute for Social and Economic Change, 2007.

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Sallie, Batson, dir. RetroAge : The four-step program to reverse the aging process. New York : Berkley Books, 1997.

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A, Yetter Jeffrey, et Langley Research Center, dir. Static performance of six innovative thrust reverser concepts for subsonic transport applications : Summary of the NASA Langley Innovative Thrust Reverser Test Program. Hampton, Va : National Aeronautics and Space Administration, Langley Research Center, 2000.

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Singer, Marilyn. Follow follow : A book of reverso poems. New York : Dial Books for Young Readers, 2013.

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MaCurdy, Thomas E. Reform reversed ? : The restoration of welfare benefits to immigrants in California. San Francisco : Public Policy Institute of California, 1998.

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TREASURY, GREAT BRITAIN. Secondary legislation for the regulation of home reversion and home purchase plans : A consultation. Norwich : HM Treasury, 2006.

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Total health turnaround : The all-natural plan to reverse adrenal fatigue, lose weight, and feel better fast. Emmaus, Pennsylvania : Rodale, 2014.

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Lemos, Patrícia Faga Iglecias. Resíduos sólidos e responsabilidade civil pós-consumo : Lei da política nacional de resíduos sólidos (Lei 12,305/2010), Decreto regulamentador (Dec. 7,404/2010), Responsabilidade compartilhada, logística reversa. São Paulo, SP, Brasil : Editora Revista dos Tribunais, 2011.

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Chapitres de livres sur le sujet "Fork reversal"

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Marks, Sheldon H. F. « Who’s a Candidate for a Vasectomy Reversal ? » Dans Vasectomy Reversal, 5–7. Cham : Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-030-00455-2_2.

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Sim, Andrew, et Angela Vick. « Reversal Agents ». Dans Essentials of Pharmacology for Anesthesia, Pain Medicine, and Critical Care, 205–18. New York, NY : Springer New York, 2014. http://dx.doi.org/10.1007/978-1-4614-8948-1_13.

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Bonnet, P., S. Lalléchère et F. Paladian. « From Electromagnetic Time-Reversal Theoretical Accuracy to Practical Robustness for EMC Applications ». Dans Electromagnetic Time Reversal, 91–144. Chichester, UK : John Wiley & Sons, Ltd, 2017. http://dx.doi.org/10.1002/9781119142119.ch3.

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Pagani, P., M. Ney et A. Zeddam. « Application of Time Reversal to Power Line Communications for the Mitigation of Electromagnetic Radiation ». Dans Electromagnetic Time Reversal, 169–87. Chichester, UK : John Wiley & Sons, Ltd, 2017. http://dx.doi.org/10.1002/9781119142119.ch5.

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Anderson, Brian E., Marcel C. Remillieux, Pierre-Yves Le Bas et T. J. Ulrich. « Time Reversal Techniques ». Dans Nonlinear Ultrasonic and Vibro-Acoustical Techniques for Nondestructive Evaluation, 547–81. Cham : Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-94476-0_14.

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Tate, Robyn L., et Michael Perdices. « Withdrawal/reversal designs ». Dans Single-Case Experimental Designs for Clinical Research and Neurorehabilitation Settings, 90–107. Abingdon, Oxon ; New York, NY : Routledge, 2018. | Series : Neuropsychological rehabilitation : a modular handbook : Routledge, 2019. http://dx.doi.org/10.4324/9780429488184-5.

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Ogryczak, Wlodzimierz, Patrice Perny et Paul Weng. « On WOWA Rank Reversal ». Dans Modeling Decisions for Artificial Intelligence, 66–77. Berlin, Heidelberg : Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/978-3-642-34620-0_8.

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De Wil, Peter Frank, Vincenzo Ficarra, George A. de Boccard et Alexandre Mottrie. « Robot-Assisted Vasectomy Reversal ». Dans Male Infertility for the Clinician, 259–64. New York, NY : Springer New York, 2013. http://dx.doi.org/10.1007/978-1-4614-7852-2_14.

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Kou, Gang, Daji Ergu, Yi Peng et Yong Shi. « IBMM for Rank Reversal ». Dans Quantitative Management, 93–105. Berlin, Heidelberg : Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/978-3-642-29213-2_6.

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Rosevear, Henry M., et Moshe Wald. « Grafting Techniques for Vasectomy Reversal ». Dans Male Infertility for the Clinician, 223–34. New York, NY : Springer New York, 2013. http://dx.doi.org/10.1007/978-1-4614-7852-2_11.

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Actes de conférences sur le sujet "Fork reversal"

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Coletta, Nancy J., et David R. Williams. « Motion reversal in peripheral retina ». Dans OSA Annual Meeting. Washington, D.C. : Optica Publishing Group, 1987. http://dx.doi.org/10.1364/oam.1987.wt3.

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At high spatial frequencies, drifting interference fringes viewed in the fovea and parafovea can appear to move opposite to their true direction. We have previously shown that aliasing by the cone mosaic is responsible for this motion reversal. We measured forced-choice psychometric functions for direction discrimination as a function of the spatial frequency of drifting vertical interference fringes. For a regular sampling lattice, the perceived direction of motion should reverse at integer multiples of the lattice Nyquist frequency. Despite disorder in the cone mosaic, the data in the fovea and parafovea agree with this prediction. At each retinal location tested, motion reversals occur at two spatial frequencies which correspond to one and two times the cone Nyquist frequency. However, in the periphery, from 10 to 25° eccentricity, the first motion reversal occurs at a lower frequency than would be predicted from cone sampling. The reason for this discrepancy is unclear, but it probably involves postreceptoral mechanisms. Nonetheless, the Nyquist frequency obtained at the second motion reversal agrees with peripheral anatomical cone spacing data.
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Li, Bin, et Manuel de Freitas. « A Procedure for Fast Evaluation of High-Cycle Fatigue Under Multiaxial Random Loading ». Dans ASME 2001 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2001. http://dx.doi.org/10.1115/detc2001/rsafp-21742.

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Abstract This paper presents a fast evaluation procedure for high-cycle fatigue (HCF) under multiaxial random loading. The recent multiaxial cycle counting method of Wang and Brown is used to identify the loading reversals. For each identified reversal, the effective shear stress amplitude is directly calculated from the component stress ranges by an equation derived from the MCE approach, which is a newly developed method to account for non-proportional loading effect. This shear stress amplitude and the maximum hydrostatic stress during the time period of an identified reversal are used to evaluate the fatigue damage for that reversal by Crossland’s criterion. The fatigue damage of the loading block is then calculated by summing the damages of all the identified reversals by Miner’s rule. Comparisons with other multiaxial HCF approaches show that the procedure is a computationally efficient and conservative engineering approach.
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Cyrus, Vaclav, Jiri Pelnar et Jan Cyrus. « Reversing of Axial Flow Fans for Ventilation ». Dans ASME 2011 Turbo Expo : Turbine Technical Conference and Exposition. ASMEDC, 2011. http://dx.doi.org/10.1115/gt2011-46062.

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Changing the flow direction in fans is frequently required in emergency situations in traffic tunnels, chemical plants and mines ventilation. Reverse flow in axial flow fan is often achieved using two methods: a) Changing direction of fan rotation and turning the stator vanes (Method I). b) Turning / resetting rotor blades during fan rotation (Method II). The required volume flow rate at flow reversal is usually at least 60% valid for normal fan working point. The motivation of the present paper is to compare the aerodynamic performance and 3D flow mechanism in fan stage at flow reversal carried out by the two methods above. In our paper conditions of the flow reversal are discussed. Theoretical relations are derived for both methods using fundamental equations valid for internal aerodynamics of axial flow compressors and fans. Parameters of three fan axial stages were measured on a 600 diameter test rig at standard and reverse conditions. The investigated fan ventilation stages had a design flow coefficient of 0.35 to 0.40 and pressure coefficient of 0.30. Flow field measurements were carried out with the use of 5-hole pressure probes in the stage planes. The blade rows flow mechanism at the standard and reverse conditions is described using test data obtained for both flow reversal methods. The flow simulation results were also used. It has been found in our investigations that moderate aerodynamic loading of the ventilation fans has better aerodynamic performance during flow reversal if Method II is used. Fan designers and users making the final decision relating to the selection of the flow reversal method should also include the reliability and cost of the reverse fan design with blade turning mechanism.
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Williams, David R. « Photoreceptor Sampling of Moving Images ». Dans Applied Vision. Washington, D.C. : Optica Publishing Group, 1989. http://dx.doi.org/10.1364/av.1989.wc1.

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A periodic moving stimulus can appear to move in the reverse direction if it is under-sampled in time, as in the case of the "wagon wheel" effect caused by an inadequate frame rate in motion pictures. Sampling by a spatial array of sensors or pixels can produce a similar motion reversal for periodic patterns moving at any velocity, if the spatial sampling frequency is too low. These artifacts are well-known to engineers who design discrete imaging systems. The artifact resulting from spatial under-sampling has been demonstrated in biological imaging systems (Goetz, 1965, Coletta and Williams, 1987). For example, insects tethered at the center of a rotating drum containing low spatial frequency vertical stripes exhibit an optomotor response: they rotate in the same direction as the stripes. However, these insects reverse their direction of motion when confronted with spatial frequencies that exceed the Nyquist frequency of their ommatidial array. This is just what one would expect from spatial aliasing by the regular array of insect ommatidia. Nancy Coletta and I have demonstrated a similar effect in the human with drifting interference fringes whose contrast is immune to optical degradation. In the parafoveal retina, high spatial frequency (but not low) gratings look like two-dimensional spatial noise and can appear to move in the opposite direction from their true direction of motion. This motion reversal can be demonstrated with a forced-choice technique. Subjects guessed the direction of motion of vertical, unity contrast fringes whose direction was randomly determined on each trial. No feedback was provided. Percent correct falls significantly below chance performance at high spatial frequencies, indicating a reversal in the perceived direction of motion. At higher frequencies, the perceived direction of motion reverses a second time, and at even higher frequencies performance settles to chance.
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Pendergrass, L. L., et R. J. Jungerman. « Ferroelectric Microdomains In Lithium Niobate Optical Modulators ». Dans Integrated and Guided Wave Optics. Washington, D.C. : Optica Publishing Group, 1988. http://dx.doi.org/10.1364/igwo.1988.tud3.

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Degradation of lithium niobate integrated optical device performance due to the reversal of ferroelectric micro-domains in localized regions has been described in Ref. 1. However, it has been assumed that these reversals can take place only at extremely high temperatures (near the Curie point) or with very high applied electric fields. Indeed, it has been shown theoretically (Ref. 2) that for pure lithium niobate at room temperature, an electric field of about 3 × 10 9 V/m applied along the crystalline c axis would be necessary to cause domain reversal. Titanium diffusion at elevated temperatures was identified in Ref. 1 as the cause of these reversals and usage of -Z-cut substrates rather than +Z-cut substrates was proposed to reduce their occurrence.
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Z. Du, Q., Y. T. Zhu, G. Fang et X. F. Gong. « Polarity Reversal Correction for Multicomponent Joint Elastic Reverse Time Migration ». Dans 73rd EAGE Conference and Exhibition incorporating SPE EUROPEC 2011. Netherlands : EAGE Publications BV, 2011. http://dx.doi.org/10.3997/2214-4609.20148977.

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Zheng, Dezhi, Haibo Ma, Armin K. Silaen et Chenn Q. Zhou. « CFD Analysis of Reversed Installation on Flow Measurements by a Plate Orifice ». Dans ASME 2019 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/imece2019-10620.

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Abstract The accidental reversal installation of an orifice plate could occur during maintenance operations and a long time may have elapsed before being noticed. The reversal installation can result in a significant mismeasurement of flow in a pipe. In the paper, a computational fluid dynamics (CFD) model has been developed to simulate the pressure and velocity distribution in a pipe with the correct and the reversed installation of an orifice plate. The results shown that there is a significant difference between the correct and reversed installation in terms of pressure. Using the CFD pressure drop results for flows in both installations, an estimate correlation between those installations was found. This result provides the method to solve the issue about the accidental reversal of an orifice plate using a correction factor.
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Qu, Xiaoyun, Tong Wang et Jongho An. « Study on the Reverse Rotating Character Driven by the Backflow on a Centrifugal Fan System ». Dans ASME Turbo Expo 2016 : Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/gt2016-57232.

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In the turbo-compressor driving system, working fluid of large capacity and high pressure is stored in the system. Once an accident happened unexpectedly, the driving power of the rotor would be shut off quickly. Owing to the pressure difference between the inlet and the outlet of the compressor, the original downstream fluid might flow back from the volute to the impeller. The backflow might propel the impeller rotating reversely compared with its working status. It would damage the bearing and sealing system. Therefore, it is necessary to avoid the rotor reversal. With the development of the economies of scale, the capacity of the compressor unit becomes larger and larger, the possibility of the rotor reversal accident might be in consideration. The reverse performance of the centrifugal impeller is related to the mass flowrate of the backflow, the backflow pressure, moment of inertia as well as the initial working rotating speed of the rotor. In order to get the quantitative relation of the parameters, a test rig was set up with a centrifugal fan. The parameter was tested on the idle processes with different initial rotating speeds. Compared with the idle process, the reduction processes of the rotating speed driven by the backflow were tested. The processes varied with the pressure and the flowrate of the backflow. In addition, three-dimension simulation on the fan was performed. Corresponding to the experimental data, numerical performance of the fan was got to verify the numerical method. The flow information in the fan with backflow was analyzed. Even the backflow passing through the impeller, there is small flowrate to the volute by the operating fan. Combined with experimental data and the numerical parameters, the theoretical analysis on the reduction process of rotating speed was carried out. The critical values of the initial working rotating speed, the pressure and the flowrate of the backflow were derived to avoid the reverse rotation. Therefore, it can be used for the fan system in the design process to prevent the reverse rotation.
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Ray, Arjun Sarathi. « A Study of the Behaviour of Flow in a Diagonal-Flow Turbomachine ». Dans ASME 1996 International Gas Turbine and Aeroengine Congress and Exhibition. American Society of Mechanical Engineers, 1996. http://dx.doi.org/10.1115/96-gt-061.

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Experiments were conducted on a diagonal-flow machine to study the behaviour of flow. Measurements showed that at reduced flow rates, reversal of flow occurs near the tip upstream of the rotor and near the hub downstream. At high flow rates, the flow reverses near tip at downstream only. In fact, there is only a limited regime of operation where the flow is not reversed before or after the impeller. The best fluid-dynamic efficiency was observed to be midway of this non-reversed flow regime. Through-flow solutions of the mean hub-to-tip streamsurface were carried out by streamline curvature computation and compared with experimental results. The comparison showed good agreement of the predicted values with the experimental data. However, attempts to compare theoretical estimates of rotor losses with experimental measurements showed that the existing loss models are inadequate for loss prediction and further work is required in this direction. The head-flow characteristic of the machine showed a droop at reduced flow rates, typical of what one usually notices in an axial-flow machine with the onset of blade stall. Study of the time history of velocity downstream of rotor illustrated that unlike rotating ‘stall-cells’ in axial-flow machines, the blade stall in the present case did not possess any regular pattern nor any unique speed of propagation. Near the hub at downstream of rotor, where the flow finally reverses upon reduction of flow rate, the stall appeared as patches of ‘blockage’ type disturbance over an otherwise systematic train of blade wakes when the flow coefficient reaches a value where the droop in the characteristic curve starts.
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Adachi, Kazuhiko, et Yosuke Sakai. « Impact Detection for Plate Based on Time Reversal Processing Using Experimentally Measured Sensor Signals of Surface Bonded PZT Patches ». Dans ASME 2006 International Mechanical Engineering Congress and Exposition. ASMEDC, 2006. http://dx.doi.org/10.1115/imece2006-14159.

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Time reversal processing for the measured sensor signal can be applied to detect not only structural damage but also impact loading of the structure. Impact identification capability of a time reversal processing using experimentally measured sensor signals is demonstrated in this paper. After measuring the electrical sensor signals corresponding to scattered wave filed of the plate experimentally, time reversal processing is applied to the measured signals in the numerical wave back propagation simulation for localizing the impact loading point on the plate. A time-reversed wave travels back through the plate and is focused on the region around a point where hits by the impact hammer. The illustrative experimental and numerical results demonstrate impact identification capability of the proposed method.
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Rapports d'organisations sur le sujet "Fork reversal"

1

Qiu, Robert C. Time-Reversal for UWB Communications Systems. Fort Belvoir, VA : Defense Technical Information Center, août 2005. http://dx.doi.org/10.21236/ada455574.

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Golding, William M. Time Reversal Techniques for Atomic Waveguides. Fort Belvoir, VA : Defense Technical Information Center, septembre 2011. http://dx.doi.org/10.21236/ada549862.

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Young, Derek P., Neil Jacklin, Ratish J. Punnoose et David T. Counsil. Time reversal signal processing for communication. Office of Scientific and Technical Information (OSTI), septembre 2011. http://dx.doi.org/10.2172/1030259.

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Ginat, David, Daniel D. Sleator et Robert E. Tarjan. A Tight Amortized Bound for Path Reversal. Fort Belvoir, VA : Defense Technical Information Center, juin 1988. http://dx.doi.org/10.21236/ada214690.

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Cheng, L., et P. Tichler. Flow reversal power limit for the HFBR. Office of Scientific and Technical Information (OSTI), janvier 1997. http://dx.doi.org/10.2172/661652.

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Cheng, Lap, et P. Tichler. Flow reversal power limit for the HFBR. Office of Scientific and Technical Information (OSTI), octobre 1995. http://dx.doi.org/10.2172/245623.

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Burke, G. J., et A. J. Poggio. Simulation of Time-Reversal Processing for Electromagnetic Communication. Office of Scientific and Technical Information (OSTI), juillet 2003. http://dx.doi.org/10.2172/15004937.

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Fouque, Jean-Pierre, et Mansoor A. Haider. Time-Reversal for Electromagnetic Waves in Complex Media. Fort Belvoir, VA : Defense Technical Information Center, juillet 2003. http://dx.doi.org/10.21236/ada421538.

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Morgan, Harold W. Decaying Army Infrastruckture : An Unexpected Opportunity for Reversal. Fort Belvoir, VA : Defense Technical Information Center, mars 1990. http://dx.doi.org/10.21236/ada220699.

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Brown, S. W. A shear reversal nozzle for efficient gas atomization. Office of Scientific and Technical Information (OSTI), décembre 1992. http://dx.doi.org/10.2172/10176477.

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