Academic literature on the topic 'Dormancy loss'
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Journal articles on the topic "Dormancy loss"
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Boon, Calvin, and Thomas Dick. "Mycobacterium bovis BCG Response Regulator Essential for Hypoxic Dormancy." Journal of Bacteriology 184, no. 24 (December 15, 2002): 6760–67. http://dx.doi.org/10.1128/jb.184.24.6760-6767.2002.
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ABSTRACT Obligately aerobic tubercle bacilli are capable of adapting to survive hypoxia by developing into a nonreplicating or dormant form. Dormant bacilli maintain viability for extended periods. Furthermore, they are resistant to antimycobacterials, and hence, dormancy might play a role in the persistence of tuberculosis infection despite prolonged chemotherapy. Previously, we have grown dormant Mycobacterium bovis BCG in an oxygen-limited Wayne culture system and subjected the bacilli to proteome analysis. This work revealed the upregulation of the response regulator Rv3133c and three other polypeptides (α-crystallin and two “conserved hypothetical” proteins) upon entry into dormancy. Here, we replaced the coding sequence of the response regulator with a kanamycin resistance cassette and demonstrated that the loss-of-function mutant died after oxygen starvation-induced termination of growth. Thus, the disruption of this dormancy-induced transcription factor resulted in loss of the ability of BCG to adapt to survival of hypoxia. Two-dimensional gel electrophoresis of protein extracts from the gene-disrupted strain showed that the genetic loss of the response regulator caused loss of the induction of the other three dormancy proteins. Thus, the upregulation of these dormancy proteins requires the response regulator. Based on these two functions, dormancy survival and regulation, we named the Rv3133c gene dosR for dormancy survival regulator. Our results provide conclusive evidence that DosR is a key regulator in the oxygen starvation-induced mycobacterial dormancy response.
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Allen, Phil S., and Susan E. Meyer. "Ecological aspects of seed dormancy loss." Seed Science Research 8, no. 2 (June 1998): 183–92. http://dx.doi.org/10.1017/s0960258500004098.
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AbstractAdvances in seed biology include progress in understanding the ecological significance of seed dormancy mechanisms. This knowledge is being used to make more accurate predictions of germination timing in the field. For several wild species whose seedlings establish in spring, seed populations show relevant variation that can be correlated with habitat conditions. Populations from severe winter sites, where the major risk to seedlings is frost, tend to have long chilling requirements or to germinate very slowly at low temperatures. Populations from warmer sites, where the major risk is drought, are non-dormant and germinate very rapidly under these same conditions. Seed populations from intermediate sites exhibit variation in dormancy levels, both among and within plants, which spreads germination across a considerable time period. For grasses that undergo dry after-ripening, seed dormancy loss can be successfully modelled using hydrothermal time. Dormancy loss for a seed population is associated with a progressive downward shift in the mean base water potential, i.e., the water potential below which half of the seeds will not germinate. Other parameters (hydrothermal time requirement, base temperature and standard deviation of base water potentials) tend to be constant through time. Simulation models for predicting dormancy loss in the field can be created by combining measurements of seed zone temperatures with equations that describe changes in mean base water potential as a function of temperature. Successful validation of these and other models demonstrates that equations based on laboratory data can be used to predict dormancy loss under widely fluctuating field conditions. Future progress may allow prediction of germination timing based on knowledge of intrinsic dormancy characteristics of a seed population and long-term weather patterns in the field.
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Soltani, Elias, Sabine Gruber, Mostafa Oveisi, Nader Salehi, Iraj Alahdadi, and Majid Ghorbani Javid. "Water stress, temperature regimes and light control induction, and loss of secondary dormancy in Brassica napus L. seeds." Seed Science Research 27, no. 3 (June 6, 2017): 217–30. http://dx.doi.org/10.1017/s0960258517000186.
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AbstractThis study investigated the induction and loss of dormancy in oilseed rape (Brassica napus). Twenty genotypes were preliminary screened; from these, two genotypes, RGS003 and Hayola 308, which possess high potential for dormancy induction (HSD) and medium potential to induce secondary dormancy (MSD), were selected. The stratification of seeds at alternating temperatures of 5–30°C (in dark) significantly relieved secondary dormancy, but dormancy was not fully released. The ψb(50) values were −1.05 and −1.06 MPa for the MSD and the HSD before dormancy induction. After inducing dormancy, the ψb(50) values for the MSD and the HSD were increased to −0.59 and −0.01 on day 0 stratification at 20°C. The hydrothermal time (θHT) value was low for one-day stratification for HSD in comparison with other stratification treatments. Water stress can induce dormancy (if the seeds have the genetic potential for secondary dormancy) and warm stratification (in dark) can only reduce the intensity of dormancy. The seeds with a high potential of dormancy induction can overcome dormancy at alternating temperatures and in the presence of light. It can, therefore, be concluded that a portion of seeds can enter the cycle of dormancy ↔ non-dormancy. The secondary dormant seeds of B. napus cannot become non-dormant in darkness, but the level of dormancy may change from maximum (after water stress) to minimum (after warm stratification). It seems that the dormancy imposed by the conditions of deep burial (darkness in combination with water stress and more constant temperatures) might be more important to seed persistence than secondary dormancy induction and release. The dormancy cycle is an important pre-requisite in order to sense the depth of burial and the best time for seed germination.
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Walck, Jeffrey L., Carol C. Baskin, and Jerry M. Baskin. "Seeds of Thalictrum mirabile (Ranunculaceae) require cold stratification for loss of nondeep simple morphophysiological dormancy." Canadian Journal of Botany 77, no. 12 (February 20, 2000): 1769–76. http://dx.doi.org/10.1139/b99-149.
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Seeds of the eastern North American herbaceous polycarpic perennial Thalictrum mirabile Small have differentiated but underdeveloped (small) embryos that are physiologically dormant at maturity in September. Physiological dormancy was broken effectively by cold stratification at 1°C, but embryos required temperatures [Formula: see text]15:6°C for growth after physiological dormancy was broken. Gibberellic acid substituted for cold stratification. Breaking of physiological dormancy in seeds exposed to natural temperatures in a greenhouse occurred during winter, and embryo growth and germination occurred in late winter - early spring. Furthermore, seeds in the greenhouse remained viable until the second and third (spring) germination seasons. Thus, T. mirabile seeds have the capacity to form a short-lived persistent soil seed bank. Buried seeds of T. mirabile apparently go through an annual dormancy-nondormancy cycle. Seeds buried in September 1994 were nondormant when exhumed in April 1995 and April 1996 and incubated in light at 25:15°C for 2 weeks, but they were dormant in June 1995 and September 1995. Seeds of T. mirabile have nondeep simple morphophysiogical dormancy. This is the first report of nondeep simple morphophysiological dormancy being broken by cold, and not by warm, stratification.
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Tuttle, Keiko M., Shantel A. Martinez, Elizabeth C. Schramm, Yumiko Takebayashi, Mitsunori Seo, and Camille M. Steber. "Grain dormancy loss is associated with changes in ABA and GA sensitivity and hormone accumulation in bread wheat,Triticum aestivum(L.)." Seed Science Research 25, no. 2 (March 9, 2015): 179–93. http://dx.doi.org/10.1017/s0960258515000057.
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AbstractKnowledge about the hormonal control of grain dormancy and dormancy loss is essential in wheat, because low grain dormancy at maturity is associated with the problem of pre-harvest sprouting (PHS) when cool and rainy conditions occur before harvest. Low GA (gibberellin A) hormone sensitivity and high ABA (abscisic acid) sensitivity were associated with higher wheat grain dormancy and PHS tolerance. Grains of two PHS-tolerant cultivars were very dormant at maturity, and insensitive to GA stimulation of germination. More PHS-susceptible cultivars were less sensitive to ABA inhibition of germination, and were either more GA sensitive or germinated efficiently without GA at maturity. As grain dormancy was lost through dry afterripening or cold imbibition, grains first gained GA sensitivity and then lost ABA sensitivity. These changes in GA and ABA sensitivity can serve as landmarks defining stages of dormancy loss that cannot be discerned without hormone treatment. These dormancy stages can be used to compare different cultivars, seed lots and studies. Previous work showed that wheat afterripening is associated with decreasing ABA levels in imbibing seeds. Wheat grain dormancy loss through cold imbibition also led to decreased endogenous ABA levels, suggesting that reduced ABA signalling is a general mechanism triggering dormancy loss.
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Jones, Steve K., Richard H. Ellis, and Peter G. Gosling. "Loss and induction of conditional dormancy in seeds of Sitka spruce maintained moist at different temperatures." Seed Science Research 7, no. 4 (December 1997): 351–58. http://dx.doi.org/10.1017/s0960258500003755.
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AbstractPretreatment of moist seeds at certain temperatures can reduce seed dormancy, but such observations represent the net effect of pretreatment. Seeds of Sitka spruce (Picea sitchensis [Bong.] Carr.) were raised to 30% moisture content and pretreated at five different temperatures between 5 and 30°C for up to 24 weeks (168 d). Subsequent ability to germinate at 10°C and viability were then determined in order to investigate the effects of pretreatment on seed dormancy and survival. There was a curvilinear, negative semi-logarithmic relationship between seed longevity and pretreatment temperature, such that Q10 for loss in viability increased from 2.6 between 10 and 20°C to 2.8 between 20 and 30°C. Simple multiplicative models combining cumulative normal frequency distributions for each of loss in viability and loss in dormancy were able to describe the changes in ability to germinate at 10°C, after pretreatment at 5, 10 and 30°C. However, in order to quantify the changes in ability to germinate observed at 10°C after pretreatment at 15°C, it was necessary also to invoke a model of dormancy reimposition, while for the results at 20°C it was necessary to postulate both dormancy reimposition and the further loss of this reimposed dormancy. It is concluded that moist seeds of Sitka spruce held at 15 and 20°C cycle between the dormant and non-dormant condition.
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Hawkins, K. K., P. S. Allen, and S. E. Meyer. "Secondary dormancy induction and release inBromus tectorumseeds: the role of temperature, water potential and hydrothermal time." Seed Science Research 27, no. 1 (January 10, 2017): 12–25. http://dx.doi.org/10.1017/s0960258516000258.
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AbstractSeeds of the winter annualBromus tectorumlose primary dormancy in summer and are poised to germinate rapidly in the autumn. If rainfall is inadequate, seeds remain ungerminated and may enter secondary dormancy under winter conditions. We quantified conditions under which seeds enter secondary dormancy in the laboratory and field and also examined whether contrastingB. tectorumgenotypes responded differently to dormancy induction cues. The study also extends previous hydrothermal time models for primary dormancy loss and germination timing inB. tectorumby using similar models to account for induction and loss of secondary dormancy. Maximum secondary dormancy was achieved in the laboratory after 4 weeks at –1.0 MPa and 5°C. Seeds in the field became increasingly dormant through exposure to temperatures and water potentials in this range, confirming laboratory results. They were released from dormancy through secondary after-ripening the following summer. Different genotypes showed contrasting responses to dormancy induction cues in both laboratory and field. To examine secondary dormancy induction and release in the field in terms of hydrothermal time parameters, we first created a model that allowed mean base water potential (Ψb(50)) to vary while holding other hydrothermal time parameters constant, as in models for primary dormancy loss under dry conditions. The second model allowed all three model parameters to vary through time, to account for changes (e.g. hydrothermal time accumulation) that could occur simultaneously with dormancy induction in imbibed seeds. Shifts in Ψb(50) could explain most changes in dormancy status for seeds retrieved from the field, except during the short period prior to dormancy induction, when hydrothermal time was accumulating. This study illustrates that hydrothermal modelling, and specifically changes in Ψb(50), can be used to characterize secondary dormancy induction and loss inB. tectorum.
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Barboza, Perry S., Sean D. Farley, and Charles T. Robbins. "Whole-body urea cycling and protein turnover during hyperphagia and dormancy in growing bears (Ursus americanus and U. arctos)." Canadian Journal of Zoology 75, no. 12 (December 1, 1997): 2129–36. http://dx.doi.org/10.1139/z97-848.
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Subadult bears were studied during their autumn hyperphagia (n = 3) and winter dormancy (n = 6). Urea kinetics were measured with 14C- and 15N-urea, protein turnover was estimated with 15N-glycine, and body composition was assessed with 3H-water. Reduced amino acid degradation in winter was indicated by declines in plasma urea and aminotransferase activities, and lower urea production than in autumn (4.7 vs. 27.5 mmol urea-N∙kg−0.75∙d−1). Only 7.5% of urea produced in hyperphagic bears was degraded and just 1.1% of the degraded N reutilized as amino-N. Dormant bears reutilized 99.7% of urea produced, indicating thorough microbial ureolysis and urea-N resorption. Low rates of body N loss during dormancy suggested losses of non-urea N as creatinine. Protein turnover rates (15.2–21.5 g∙kg−0.75∙d−1) were similar between seasons and reflected the apparent maintenance of hepatic, intestinal, and muscular functions through dormancy. Protein synthesis accounted for 32% of energy expended in dormancy, which was mainly (91.5%) derived from fat oxidation. Consistent organ function and body temperature in dormant bears enables recycling of urea-N, which minimizes body protein loss and conserves mobility. In comparison with heterothermic hibernation, ursid dormancy would provide greater flexibility during winter and facilitate rapid resumption of foraging and growth in spring.
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Buczacki, Simon J. A., Semiramis Popova, Emma Biggs, Chrysa Koukorava, Jon Buzzelli, Louis Vermeulen, Lee Hazelwood, Hayley Francies, Mathew J. Garnett, and Douglas J. Winton. "Itraconazole targets cell cycle heterogeneity in colorectal cancer." Journal of Experimental Medicine 215, no. 7 (May 31, 2018): 1891–912. http://dx.doi.org/10.1084/jem.20171385.
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Cellular dormancy and heterogeneity in cell cycle length provide important explanations for treatment failure after adjuvant therapy with S-phase cytotoxics in colorectal cancer (CRC), yet the molecular control of the dormant versus cycling state remains unknown. We sought to understand the molecular features of dormant CRC cells to facilitate rationale identification of compounds to target both dormant and cycling tumor cells. Unexpectedly, we demonstrate that dormant CRC cells are differentiated, yet retain clonogenic capacity. Mouse organoid drug screening identifies that itraconazole generates spheroid collapse and loss of dormancy. Human CRC cell dormancy and tumor growth can also be perturbed by itraconazole, which is found to inhibit Wnt signaling through noncanonical hedgehog signaling. Preclinical validation shows itraconazole to be effective in multiple assays through Wnt inhibition, causing both cycling and dormant cells to switch to global senescence. These data provide preclinical evidence to support an early phase trial of itraconazole in CRC.
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Cochrane, Anne. "Are we underestimating the impact of rising summer temperatures on dormancy loss in hard-seeded species?" Australian Journal of Botany 65, no. 3 (2017): 248. http://dx.doi.org/10.1071/bt16244.
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Short duration dry heat shock similar to the heat of fire is known to be effective in alleviating physical dormancy in seeds, but are we underestimating the impact of the cumulative heat dose of summer soil temperatures on dormancy loss in hard-seeded species in the context of a changing climate? This study investigated short and long duration dry heat treatments in seeds of four Acacia species (Fabaceae) from South-West Western Australia. Seeds were treated at 90, 100, 110 and 120°C for 10 and 180 min (‘fire’) and at fluctuating temperatures of 30/20, 55/20, 65/20°C for 14, 28, 56 and 112 days (‘summer’). The non-dormant seed fraction of each species was low, but seeds were highly viable after scarification. The results indicate the presence of species-specific temperature thresholds for dormancy loss with duration of heating slightly less important than temperature for dormancy break. Seeds remained highly viable after all long duration treatments but short duration heat shock treatments above 110°C resulted in increased seed mortality. Although cumulative periods of lower fluctuating temperatures were less effective in breaking physical dormancy than the heat of fire in three of the four species, more than 40% of seeds of Acacia nigricans (Labill.) R.Br. lost dormancy after 28 days at 65/20°C. These potentially disturbing findings suggest that long hot summer conditions may compromise soil seed bank longevity over time and may be detrimental to the bet-hedging ability afforded by a hard seed coat in some species in the face of climate warming forecasts for the region.
Dissertations / Theses on the topic "Dormancy loss"
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Elder, R. H. "DNA repair and replication during dormancy and loss of viability of seeds." Thesis, University of Oxford, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.370250.
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Bair, Necia B. "A hydrothermal after-ripening time model of seed dormancy loss in Bromus tectorum /." Diss., CLICK HERE for online access, 2004. http://contentdm.lib.byu.edu/ETD/image/etd487.pdf.
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Bair, Necia Beck. "A Hydrothermal After-ripening Time Model of Seed Dormancy Loss in Bromus tectorum." BYU ScholarsArchive, 2004. https://scholarsarchive.byu.edu/etd/533.
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After-ripening, the process of seed dormancy loss in dry storage is associated with a decrease in the mean base water potential, one of the parameters of hydrothermal time. The rate of change of the mean base water potential is assumed to be a linear function of temperature above a specific base temperature and as a result can be described by a thermal after-ripening (TAR) time model, an extension of hydrothermal modelling. The thermal requirement for after-ripening is the thermal time necessary for the modelling base water potential of the seed to shift from its original value to its final value. In order to include the effects of water potential on the rate of dormancy loss, a hydrothermal after-ripening (HTAR) time model was developed. Laboratory and field studies were conducted using seeds of Bromus tectorum. These studies identified four important ranges of water potential that influence the rate of dormancy loss. The ranges are identified as follows: seeds experiencing soil water potentials seeds experiencing soil water potentials <-400 MPa do not after-ripen, between -400 MPa and -150 MPa seeds after-ripen as a function of temperature (T) and water potential (Ψ), seeds experiencing water potentials >-150 MPa after-ripen as a linear function of temperature, and somewhere above -40 MPa seeds are too wet to after-ripen. These ranges suggest that specific reaction thresholds associated with non-fully imbibed seeds also apply to the process of after-ripening. The HTAR model for B. tectorum seeds generally improved predictions of dormancy loss in the field under soil conditions that were too dry for TAR alone. Reduced after-ripening rate under extremely dry conditions is ecologically relevant in explaining how seeds may prolong dormancy under high soil temperature conditions.
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Linthicum, Will H. "Effects of PTEN Loss and Activated KRAS Overexpression on Viscoelasticity, Adhesion, and Mechanosensitivity of Breast Epithelial Cells." Digital WPI, 2019. https://digitalcommons.wpi.edu/etd-dissertations/559.
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Therapeutics targeting the PI3K (phosphatidylinositol 3-kinase) and the Ras/MAPK (mitogen-activated protein kinases) pathways have potential as non-toxic treatments for triple-negative breast cancer due to their frequent over-activation in several forms of cancer. Interestingly, the PI3K and Ras/MAPK pathways have been shown to incite cancer dormancy behavior individually and tumorigenic behavior in unison when induced in healthy breast epithelial cells (MCF-10A) in vivo. Tumorigenesis and metastasis are heavily reliant on the specific mechanical and adhesive properties of cells, including decreased stiffness, increased mechanosensitivity, and decreased adhesion. However, the describe cellular behaviors are poorly understood for dormant cancer phenotypes. Understanding the mechanical and adhesive behaviors of MCF-10A cells as a function of PI3K and/or Ras/MAPK pathway over-activation further explores the cross-talk enabling unique dormant and tumorigenic characteristics. Cellular viscoelasticity and adhesion were measured for MCF-10A cells with PTEN (phosphatase and tensin homolog) knockout and activated KRAS (Kristen rat sarcoma viral oncogene homolog) overexpression to activate the PI3K and Ras/MAPK pathways respectively with atomic force microscopy. PTEN knockout alone has no observable influence on cell adhesion but resulted in softer cells with less organized cytoskeleton. Activated KRAS overexpression increased cell stiffness and cell adhesion regardless of PTEN expression level. Moreover, the overexpression of activated KRAS enhanced the sensitivity of cells to the substrate stiffness. The findings suggest that the cancer-associated pathways PI3K and Ras/MAPK regulate cell adhesion and mechanics to promote tumor formation and metastasis. More importantly, the results that signify mutations of different molecular pathways associated with cancer dormancy regulate cell mechanics differently suggests that cell stiffness is a biomarker that detects and differentiates different types of dormant cancers.
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Sueldo, Rolando. "Évolution de paramètres caractéristiques de la physiologie de l'eau lors de la dormance et de sa levée dans les tubercules de stachys sieboldi, MIQ. Et de helianthus tuberosus. Relations avec le métabolisme lipidique chez hélianthus." Clermont-Ferrand 2, 1990. http://www.theses.fr/1990CLF21234.
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L'etude des parametres hydriques chez le topinambour pendant la dormance et sa levee a permis de mettre en evidence un role de l'eau dans ces deux processus physiologiques. Cette etude met en evidence qu'il y a des transfert d'eau dans les tubercules. Ces transferts apparaissent a des moments bien precis lors du stockage de ces tubercules. Ces mouvement d'eau jouer un role important dans la mise en place de la croissance tuberisee ou longue. Ces mouvements d'eau peuvent etre lies a des modifications des membranes et du protoplasme cellulaire. L'etude des modifications des moleculaires phosphorylees apporte des renseignements supplementaires sur les processus qui induisent la resistance au froid et/ou la levee de dormance. Il ressort que ces processus commencent tres tot et que les variations du phosphore lipidique et du phosphore soluble dans un milieu acide, de la region sous-apicale, peuvent servir comme marqueurs de la levee de dormance physiologique. Il faut aussi signaler que les sterols doivent jouer un role tres important dans la levee de dormance, en ce qui concerne les mouvements d'eau, de metabolistes et eventuellement dans des modifications des flux de ca#2#+ transmembranaires. Les etudes qui ont ete realisees sur le plasmalemme pendant la levee de dormance (activite de l'atpase, composition en phospholipides et fluidite) permettent de dire que le plasmalemme se reorganise durant cette periode, ce qui lui fait acquerir de nouvelles proprietes morphogenetiques
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Simões, Fabiano. "Paramètres hydriques chez différentes espèces angiospermes ligneuses de climat tempéré lors des phases de dormance et de croissance." Phd thesis, Université Blaise Pascal - Clermont-Ferrand II, 2011. http://tel.archives-ouvertes.fr/tel-00868104.
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La connaissance des processus physiologiques, soit dans la phase de repos, soit pendant le développement végétatif, est important dans l'adaptation des angiospermes ligneuses tempérées, plutôt sur la question de la gestion de l'eau par la plante. Les objectifs de cette étude étaient d'évaluer la teneur de l'eau et le métabolisme des hydrates de carbone pendant l'état d'avancement de la dormance chez les poiriers, d'évaluer les stratégies d'utilisation de l'eau chez deux espèces ligneuses (pommier et noyer), qui ont été soumis à trois niveaux de déficit hydrique, et finalement, d'évaluer la fiabilité de la technique d'injection d'air pour provoquer la cavitation dans trois espèces d'angiospermes ligneuses. Lors de la première expérience, menée pendant l'automne et l'hiver 2008 au Brésil, nous avons utilisé les cultivars de poiriers et de 'Packham Triumph' et 'Housui'. La deuxième expérience a été développée en France au cours de l'été 2009, avec des pommiers et des noyers sous stress hydrique. La troisième expérience a été réalisée en France en 2009 avec trois espèces d'angiospermes ligneuses avec différentes longueurs de vaisseaux du xylème, Betula pendula, Prunus persica et Quercus robur. D'après les résultats, on a pu conclure que la teneur de l'eau dans les tissus peut être un marqueur de la progression de dormance de la 'Packham Triumph'. Cependant, les données ne sont pas concluantes pour la 'Housui'. La fermeture des stomates peut être un paramètre important dans la prévention de la cavitation du xylème chez les noyers et pommiers soumis à un déficit hydrique du sol. Lors du régime de sécheresses sévères, le pommier conserve les stomates partiellement ouverts, ce qui indique une plus grande tolérance de cette espèce à la sécheresse par rapport au noyer. Enfin, la technique d'utilisation de l'injection d'air avec des caméras d'air à deux sorties est fiable pour les espèces dont le xylème a une porosité diffuse, dès qu'on utilise des caméras courtes et des échantillons de branches qui ont une longueur plus grande que les vaisseaux du xylème.
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Wilson, Leanne C. "Characteristics of black medic (Medicago lupulina L.) seed dormancy loss in Western Canada." 2005. http://hdl.handle.net/1993/7913.
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Cover crops are an important innovation in sustainable cropping systems. The successful use and management of black medic (Medicago lupulina L.) as a self-regenerating cover crop requires a better understanding of its physical seed dormancy. In order to break this seed dormancy, it appears that a low temperature 2-stage seed softening process is required. However, whether or not this 2-stage process is required for black medic seed softening in Western Canada is unclear. Also, the influence of the presence of a companion crop, medic population type, seed burial depth and seed production environment on black medic production and seed softening is unknown. Field and controlled environment studies were established in 2003 and 20O4 in an effort to address these questions. The results from a field study conducted in different prairie environments showed that although, seed production environment, the presence of a companion crop, and medic population affected the growth and development of the black medic plants, they did not affect initial seed dormancy. A second field study tested the effect of seed production environment, seed burial depth and population on seed softening. Results indicated that there was an effect of population on summer seed softening, which suggested that there were differences in seed dormancy between a population of black medic that had been subjected to selection pressures (e.g., herbicides, competition) for 12 years versus one that had not (Foundation stock). Therefore, this suggests that some genetic drift had occurred within the population. The results also indicated that there was an effect of seed burial depth on seed softening, with more seed softening occurring for the buried seed during winter/spring and more for the surface seed during summer, and these differences appeared to be somewhat linked to differences in soil temperature. Results of this field study suggested that black medic in Western Canada goes through a 2-stage softening process. Hence, a controlled environment study was established to test this hypothesis. Results from both studies confirmed that a 2-stage softening process is required for black medic softening in western Canada. Stage 1 requirements appear to be met by exposing seed to temperatrues between-5oC and 5oC for at least 4 weeks, while exposure of the seed to a low fluctuating temperature (e.g. 15/6oC) for a short period of time (i.e., approximately 4 days) appears to meet stage 2 requirements. In summary, this research has provided us with valuable information about black medic seed softening under Western Canadian conditions, which will hopefully lead to a better understanding of how to best manage and utilize black medic as a self-regenerating cover crop in a Western Canadian cropping system.
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Meisch, Sarah. "Translating and (re)constructing the self in a different language: exploring the language memoirs "Lost in translation" by Eva Hoffman and "Heading south, looking north" by Ariel Dorman." Thesis, 2011. http://hdl.handle.net/10539/10907.
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Ph.D. Faculty of Humanities, University of the Witwatersrand, 2011This thesis investigates the trope of ‘lost in translation’ with regard to immersion in another language and aims to show that the notion requires revisiting in order to test the validity of the contention of irretrievable loss and lack in self-translation. Exploring the language memoirs Lost in Translation by Eva Hoffman and Heading South, Looking North by Ariel Dorfman, the research shows that whilst there is indeed substantial loss, disorientation and estrangement involved in transferring the self into another language and culture, valuable gains and positive personal growth nevertheless emerge. Primarily the thesis examines how, due to the role of language and culture in the formation of the self, the process entails translation and (re)construction of the self, which inevitably involves modification. In language memoirs the inherent properties of autobiographical writing add another dimension to this translation. In this way, given the multifaceted and fluid nature of identity, the process of self-translation attests to the potential limitlessness of identity and is presented as a heightened version of standard identity dilemmas and the lifelong construction of the self. In the knowledge of their complexity and the need for continual revision of the self, Hoffman and Dorfman recognise the misplaced nostalgia for a fixed and cohesive self, and embrace the wider access to identity options and means of expression that living with more than one language allows them. Enhanced self-consciousness, expanded perspectives and further aspects of the self that are revealed in the new language lead to personal growth as well as fuel creativity, serving as an impetus for writing. These authors are therefore not only ‘lost in translation’ but also ‘found’ and principally ‘altered’. The notion of ‘lost in translation’ is thus established as insufficient in describing the experience of the self in language memoirs, and the rewriting of the self in another language rather necessitates a theory of overriding transformation that acknowledges both losses and gains. Translation of the self thus unfolds as a metamorphosis that does not replace one self with another but instead embraces aspects of both languages and constructs a palimpsest-like interlayering of a multidimensional identity.
Books on the topic "Dormancy loss"
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DeMacon, Victor Louis. Loss of seed dormancy and the relationship between dormancy and embryo culture in wheat (Triticum aestivum L.). 1995.
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Kurt T, Lash. The Lost History of the Ninth Amendment. Oxford University Press, 2009. http://dx.doi.org/10.1093/acprof:oso/9780195372618.001.0001.
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The Ninth Amendment has had a remarkably robust history, playing a role in almost every significant constitutional debate in American history, including the controversy over the Alien and Sedition Acts, the struggle over slavery, and the constitutionality of the New Deal. Until very recently, however, this history has been almost completely lost due to a combination of historical accident, mistaken assumptions, and misplaced historical documents. Drawing upon a wide range of primary sources, most never before included in any book on the Ninth Amendment or the Bill of Rights, this book recovers the lost history of the Ninth Amendment and explores how its original understanding can be applied to protect the people's retained rights today. The most important aspect of this book is its presentation of newly uncovered historical evidence which calls into question the currently presumed meaning and application of the Ninth Amendment. The evidence not only challenges the traditional view regarding the original meaning of the Ninth Amendment, it also falsifies the common assumption that the Amendment lay dormant prior to the Supreme Court's “discovery” of the clause in Griswold v. Connecticut . As a history of the Ninth Amendment, the book recapitulates the history of federalism in America and the idea that local self-government is a right retained by the people. This issue has particular contemporary salience as the Supreme Court considers whether states have the right to authorize medicinal use of marijuana, refuse to assist the enforcement of national laws like the Patriot Act, or regulate physician-assisted suicide. The meaning of the Ninth Amendment has played a key role in past Senate confirmation hearings for Supreme Court justices and the current divide on the Court regarding the meaning of the Ninth Amendment makes it likely the subject will come up again during the next set of hearings.
Book chapters on the topic "Dormancy loss"
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Shaik, Shavali, Pengda Liu, Zhiwei Wang, and Wenyi Wei. "Loss of Cdh1 Triggers Premature Senescence in Part via Activation of Both the RB/E2F1 and the CLASPIN/CHK1/P53 Tumor Suppressor Pathways." In Tumor Dormancy, Quiescence, and Senescence, Volume 2, 207–17. Dordrecht: Springer Netherlands, 2013. http://dx.doi.org/10.1007/978-94-007-7726-2_20.
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Finch-Savage, W. E., and H. A. Clay. "The Influence of Embryo Restraint During Dormancy Loss and Germination of Fraxinus excelsior Seeds." In Basic and Applied Aspects of Seed Biology, 245–53. Dordrecht: Springer Netherlands, 1997. http://dx.doi.org/10.1007/978-94-011-5716-2_27.
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Maun, M. Anwar. "Seed germination and seedling establishment." In The Biology of Coastal Sand Dunes. Oxford University Press, 2009. http://dx.doi.org/10.1093/oso/9780198570356.003.0010.
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For the transformation of a seed to a seedling complex physical and biochemical changes occur within a seed before germination can proceed. Germination is controlled by diverse seed dormancy mechanisms in plant species that delays germination until the conditions are most favourable for seed germination and seedling establishment (Thompson 1970). Baskin and Baskin (1998) identified four benefits for the evolution of seed dormancy in plants: (i) persistence in risky environments as seed banks, (ii) decreased intraspecific competition, (iii) improved chances of seedling establishment and (iv) increased fitness (seed production) of the individual and the species as a whole. They showed that seed dormancy may be caused by any one of physiological, morphological, physical, chemical and mechanical constraints or by a combination of more than one of these factors. For instance, seeds may possess an embryo with a physiological inhibiting mechanism, immature embryo, impermeable seed coat or may contain chemical inhibitors and hard woody fruit walls. In all of these cases seed dormancy is eventually broken by one or more of the following treatments: after ripening, heat treatment, cold temperature stratification, prolonged exposure to high temperatures, exposure to light, softening of seed coat by microbes or physical scarification, leaching of inhibiting chemicals, ageing of seeds and other subtle changes in the habitat. In temperate North America with snow cover during winter months the seeds of a large majority of sand dune species—Cakile edentula, Ammophila breviligulata, Calamovilfa longifolia, Iva imbricata, Croton punctatus, Uniola paniculata—and others require cold stratification at <4°C for 4–6 weeks to break their dormancy requirements. Seeds of some species such as A. breviligulata and U. paniculata that require cold stratification at the northern end of their range lose this requirement in the south (Seneca 1972). At southern locations exposure to high temperatures may be required to fulfil the dormancy requirements. Winter annuals, Vulpia ciliata, Cerastium atrovirens, Mibora minima and Saxifraga tridactylites, that grow and mature their seeds in early summer on sand dunes at Aberffraw, North Wales, require exposure to high soil temperatures to overcome a state of dormancy in a certain proportion of seeds at the time of dispersal (Carey and Watkinson 1993; Pemadasa and Lovell 1975).
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Collins, Wilkie. "Chapter XVII." In Jezebel's Daughter. Oxford University Press, 2016. http://dx.doi.org/10.1093/owc/9780198703211.003.0049.
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The departure from the house was interrupted by an unforeseen cause of delay. Jack refused to follow the hearse, with Doctor Dormann and Mr Keller. ‘I won’t lose sight of her!’ he cried—‘no! not for a moment! Of all living creatures, I must be the...
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Maun, M. Anwar. "Seed banks." In The Biology of Coastal Sand Dunes. Oxford University Press, 2009. http://dx.doi.org/10.1093/oso/9780198570356.003.0009.
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The soil seed bank refers to a reservoir of viable seeds present on the soil surface or buried in the soil. It has the potential to augment or replace adult plants. Such reservoirs have regular inputs and outputs. Outputs are losses of seeds by germination, predation or other causes, while inputs include dispersal of fresh seeds from local sources and immigration from distant sources (Harper 1977). Since sand dunes are dynamic because of erosion, re-arrangement or burial by wind and wave action, efforts to find seed banks have largely been unsuccessful. Following dispersal, seeds accumulate in depressions, in the lee of plants, on sand surfaces, on the base of lee slopes and on the driftline. These seeds are often buried by varying amounts of sand. Buried seeds may subsequently be re-exposed or possibly lost over time. However, the existence of a seed bank can not be denied. Plant species may maintain a transient or a persistent seed bank depending on the longevity of seeds. In species with transient seed banks, all seeds germinate or are lost to other agencies and none is carried over to more than one year. In contrast, in species with a persistent seed bank at least some seeds live for more than one year. The four types of seed banks described by Thompson and Grime (1979) provide useful categories for discussion of coastal seed bank dynamics of different species. Type I species possess a transient seed bank after the maturation and dispersal of their seeds in spring that remain in the seed bank during summer until they germinate in autumn. Type II species possess a transient seed bank during winter but all seeds germinate and colonize vegetation gaps in early spring. Seeds of both types are often but not always dormant and dormancy is usually broken by high temperatures in type I and low temperature in type II. Type III species are annual and perennial herbs in which a certain proportion of seeds enters the persistent seed bank each year, while the remainder germinate soon after dispersal, and Type IV species are annual and perennial herbs and shrubs in which most seeds enter the persistent seed bank and very few germinate after dispersal.
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Nossin, Jan J. "Volcanic Hazards in Southeast Asia." In The Physical Geography of Southeast Asia. Oxford University Press, 2005. http://dx.doi.org/10.1093/oso/9780199248025.003.0027.
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Active volcanism in Southeast Asia is associated with marked zones of activity in the Earth’s crust that run through south and east Indonesia and the Philippines. These zones are also characterized by frequent earthquakes and a measurable movement of tectonic plates, often in the order of 5 cm yr−1. The underlying mechanism is that of subduction of oceanic plates below continental plates; the rigidity of the moving plates causes ruptures and shockwise adjustments (earthquakes). The oceanic plate, while being under thrust, sinks down to great depths below the continental plate and in the process loses its rigidity owing to heating and part assimilation into the underlying magma. Earthquakes are caused in the zone where the subducted plate is still rigid. Chapter 1 in this book puts this phenomenon in the regional context. Volcanism in this zone is marked by frequent eruptions, mostly violent and of an explosive nature. It is manifest in distinct belts that comprise all (or nearly all) of the Philippines, and large parts of Indonesia with the exception of, roughly speaking, Kalimantan and Papua. The violence of the eruptions poses threats to human settlements in the surroundings of the volcanoes, to the cultivated lands, and the infrastructure. These threats may occur during and after the actual eruption, and they may indirectly cause other hazards as well. Moreover, volcanoes in apparent dormancy that have not erupted in historical times may still come to life as the interval between eruptions may be very long. In the present chapter these hazards will be discussed. Natural hazards have been defined in four ways, of which the 1982 definition of the United Nations Disaster Relief Co-ordinator (UNDRO) seems appropriate to follow in the context of volcanic hazards (Alexander 1993). UNDRO defines natural hazards as ‘the probability of occurrence within a specific period of time and within a given area of a potentially damaging phenomenon’. A hazard therefore may represent a situation with the possibility of a disaster that may affect the population and the environment which are in some degree of vulnerability.
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deBuys, William. "Janos: A Mirror in Time." In A Great Aridness. Oxford University Press, 2011. http://dx.doi.org/10.1093/oso/9780199778928.003.0009.
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The rains have forsaken El Cuervo for nearly a year, and the mountain-ringed plain that used to be a prairie is as naked as a parking lot. Not a blade of grass is in sight, scarcely a bush. A few low mesquites, defoliated and dormant, hug the parched ground, the wind having packed into their thorny embrace the dried-out stems of last year’s tumbleweeds. Except in the burrows of the kangaroo rats, nothing can be hidden here. A lost coin or key would shout its presence, much as the potsherds do on the mounds of the ancient pueblo by the arroyo. Every edible thing has been consumed, every plant nipped off at the level of the ground. Even the soil is leaving, blown away, tons to the acre, by winds that sweep down from the Sierra Madre, a dozen miles to the west. If you were to make your way to the top of one of the chipped-tooth peaks of the sierra (no small task), you would be able to look down into great canyons. One of those canyons belongs to the Río Gavilán, where in 1936 Aldo Leopold glimpsed a kind of ecological heaven that no longer exists. From atop the peak you would also see for great distances, certainly as far as Janos, the crossroads and market town through which nearly every visitor to this northwest corner of Chihuahua passes, and on a dustless day you might see the gritty penumbra of Ciudad Juárez and El Paso, far on the northeastern horizon. The air is dry, and here it is empty of pollution, which makes El Cuervo and its environs a good place for looking long distances, even into the past. One way to understand changes in the land is to visit a place that shows how things used to be. That’s what Leopold realized when he visited the Río Gavilán. He saw it as a fragment of the Southwest that had escaped the pressures of white settlement, and he recognized it as a mirror of how Arizona and New Mexico used to be, back in the days when the Apaches still roamed their homeland in freedom.
Conference papers on the topic "Dormancy loss"
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Thompson, Keyata N., Rebecca A. Whipple, Monica S. Charpentier, Amanda E. Boggs, Lekhana Bhandray, Kristi R. Chakrabarti, Stuart S. Martin, and Michele I. Vitolo. "Abstract A32: Cell dormancy and tumorigenicity due to PTEN loss." In Abstracts: AACR Special Conference: Targeting the PI3K-mTOR Network in Cancer; September 14-17, 2014; Philadelphia, PA. American Association for Cancer Research, 2015. http://dx.doi.org/10.1158/1538-8514.pi3k14-a32.
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Luo, Xiao-Lin, Cheng-Cheng Deng, Ji-Hong Liu, and Li-Wu Fu. "Abstract 5503: Loss of MED12 induces tumor dormancy in human ovarian cancer." In Proceedings: AACR Annual Meeting 2018; April 14-18, 2018; Chicago, IL. American Association for Cancer Research, 2018. http://dx.doi.org/10.1158/1538-7445.am2018-5503.
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Cooley, Megan K., and Jeremy Chien. "Abstract POSTER-BIOL-1310: Regulation of tumor dormancy by extracellular matrix remodeling as a result of increased TGF-beta signaling and loss of HtrA1 in ovarian cancer." In Abstracts: 10th Biennial Ovarian Cancer Research Symposium; September 8-9, 2014; Seattle, WA. American Association for Cancer Research, 2015. http://dx.doi.org/10.1158/1557-3265.ovcasymp14-poster-biol-1310.
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Carlini, Maria J., Paloma Bragado, Paula F. Vazquez, Elisa D. Bal de Kier Joffe, Lydia I. Puricelli, and Julio A. Aguirre-Ghiso. "Abstract 5236: Potential loss of p53/p21 function in a murine lung adenocarcinoma cell line prevents TGFβ1-induced dormancy despite p38α/β activation and DEC2 and p27 induction." In Proceedings: AACR 103rd Annual Meeting 2012‐‐ Mar 31‐Apr 4, 2012; Chicago, IL. American Association for Cancer Research, 2012. http://dx.doi.org/10.1158/1538-7445.am2012-5236.
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Wu, Xianzhong, Youke Wang, Zhitong Wang, and Zhihua Gao. "Changes of Soil Water and Heat during Plant Dormancy in the Semi-arid Loess Hilly Region under Film Mulching." In 2017 7th International Conference on Education, Management, Computer and Society (EMCS 2017). Paris, France: Atlantis Press, 2017. http://dx.doi.org/10.2991/emcs-17.2017.316.
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Dawson, S. J., A. Russell, and A. Patterson. "Emerging Techniques for Enhanced Assessment and Analysis of Dents." In 2006 International Pipeline Conference. ASMEDC, 2006. http://dx.doi.org/10.1115/ipc2006-10264.
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Dents can occur either during pipeline construction e.g., in the form of rock-induced dents or as a result of the handling and back-fill processes or in-service, e.g., excavator impact. If failure as a result of a dent is not immediate, it is possible that the induced dent and/or defect combination can deteriorate in service and cause failure at some time after the initial impact. Often incidents of dents go unreported and the challenge to the pipeline operator is the identification of those defects that may threaten the future integrity of the pipeline from those defects that are dormant and require no further action. Most commonly, ILI metal loss and geometry tools (and in some cases ILI crack detection tools) are used to detect and report the characteristics and dimensions of dent defects. The ILI tools can provide information on the location, shape of the deformation, the nature of the damage i.e., the association with other features (metal loss, cracks, long seam or girth welds). Indeed, dents are found in the majority (> 80%) of pipeline miles inspected; with more than 50% of pipelines containing 10 or more dents. Although the pipeline industry does recognize the potential threat from dents, much of the published guidance is limited to a combination of the nature of the damage (e.g., presence of metal loss, stress risers, location etc) and a simple depth-based assessment of the deformation. In the US, prescriptive rules of this type are in place to provide operators with the timescale for the investigation and remediation of different forms of dents. However, with unintentional releases still occurring in-service from dents (from both excavator impact damage and of construction origin) the current industry thinking and research supports the use of more advanced assessment techniques (beyond the depth-based rules). These enhanced assessment techniques make use of the detailed dent profile information obtained from high-resolution geometry tools and other supporting information on the presence and severity of stress risers from ILI tools. Indeed, the US regulations do allow operators an option to engage such techniques to re-evaluate the prescriptive timescales for certain dent categories. This paper describes two levels of enhanced dent assessment that can be utilized to rank dents in order of severity and to assess their significance and need for remediation and discusses their application supported by real case study information.
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Barnett, Ralph L. "Safety of Fitness Equipment Cables." In ASME 2013 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/imece2013-63876.
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There is a family of fitness machines that provides a manual workout task requiring the user to push or pull against a resistance provided by a stack of weight plates. The weight system is usually linked with a single cable to a gripping or user interface device to produce a constant resistance. A fracture of the tensioned cable along its length or at its end connectors causes a sudden acceleration of the grip or other interface device driven by the operator’s push or pull. The sudden loss of resistance often results in an exerciser pulling a heavy bar into his or her face. Because falling weights, accelerating grips and rapidly unloading muscles are all hazardous, manufacturers of exercise machines want to maintain the structural integrity of the cables. To accomplish this, manufacturers usually recommend “scheduled servicing” of their cables. This Preventive Maintenance (PM) strategy is frustrated by nylon sheathing that hides the cable failures. Further, the swedged or silver soldered connectors often fail covertly by internal fatigue fractures. A more effective PM strategy has been adopted by many manufacturers called “Scheduled Replacement”; they advocate annual cable replacement. Here the nemeses are sloth and greed, best expressed by the philosophy, “if it ain’t broke, don’t fix it.” As a first consideration of fault tolerant design, a redundant duplication of the cable system was added to a fitness machine; this is called “active redundancy.” This paper demonstrates the inadequacy of active redundancy for eliminating the catastrophic failure mode. Instead, the adoption of a “dormant/standby” redundancy is shown to provide the requisite safety. The proposed system not only eliminates the “fail-to-danger” mode, it provides the most economical use of the cable in the sense that it never discards a cable until its life is exhausted.
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Chen, Weixing, Yongwang Kang, Reg Eadie, Richard Kania, Greg Van Boven, and Robert Worthingham. "Achieving Maximum Crack Remediation Effect From Optimized Hydrotesting." In 2012 9th International Pipeline Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/ipc2012-90635.
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Hydrostatic testing is a key method for managing SCC in oil and gas pipelines. Benefits are achieved by eliminating defects above a critical size for the hydrotest pressure and hence achieving a post-test period without operating failure. Other benefits are related to temporary growth retardation after hydrotest because of crack tip blunting. Conversely, benefits of such a test could be offset by stable flaw growth in the previously dormant population and growth of cracks during hydrostatic loading. Although this type of growth behaviour has been previously analyzed, it was only assessed from tests in air, which neglects the effects of corrosive environments. Recent research has shown that crack growth can occur during hydrotests at much smaller crack dimensions than those originally analyzed. The adverse effect of hydrotesting is negligible if it initiates crack growth only on large-size cracks that are near the final stage of pipeline life. However, benefits of hydrotest would become uncertain if hydrostatic loading induces crack growth when crack dimensions are relatively small. This reduction in pipeline remaining lifetime by hydrostatic testing can be significant considering the fact that several hydrotests may be performed in the lifetime of a pipeline. Although hydrotests would usually re-condition the crack tip so that a lower crack growth rate can be expected for a limited time, it is questionable whether the reduced growth rate would compensate for the loss of life because of the crack growth during hydrotesting. Therefore, the overall benefits of hydrotesting must be evaluated from the viewpoint of life extension and pipeline safety. Effects of hydrostatic tests in this investigation were analyzed based on two competing morphological conditions at the crack tip before, during and after hydrostatic testing, that is, crack tip blunting and crack tip sharpening. Crack tip sharpening is related to the hydrogen effects and mechanisms of cyclic loading, while the crack tip blunting is attributed to low temperature creep of the pipeline steels. From the investigation, strategies aimed at achieving maximum crack remediation are proposed.