Littérature scientifique sur le sujet « Regulation of the mode of division »
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Articles de revues sur le sujet "Regulation of the mode of division"
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Joly, Aurélia, et Raphaël Rousset. « Tissue Adaptation to Environmental Cues by Symmetric and Asymmetric Division Modes of Intestinal Stem Cells ». International Journal of Molecular Sciences 21, no 17 (2 septembre 2020) : 6362. http://dx.doi.org/10.3390/ijms21176362.
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Tissues must adapt to the different external stimuli so that organisms can survive in their environments. The intestine is a vital organ involved in food processing and absorption, as well as in innate immune response. Its adaptation to environmental cues such as diet and biotic/abiotic stress involves regulation of the proliferative rate and a switch of division mode (asymmetric versus symmetric) of intestinal stem cells (ISC). In this review, we outline the current comprehension of the physiological and molecular mechanisms implicated in stem cell division modes in the adult Drosophila midgut. We present the signaling pathways and polarity cues that control the mitotic spindle orientation, which is the terminal determinant ensuring execution of the division mode. We review these events during gut homeostasis, as well as during its response to nutrient availability, bacterial infection, chemical damage, and aging. JNK signaling acts as a central player, being involved in each of these conditions as a direct regulator of spindle orientation. The studies of the mechanisms regulating ISC divisions allow a better understanding of how adult stem cells integrate different signals to control tissue plasticity, and of how various diseases, notably cancers, arise from their alterations.
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Kim, K. M., T. Ishigami, D. Hata, K. Yamaoka, M. Mayumi et H. Mikawa. « Regulation of cell division of mature B cells by ionomycin and phorbol ester. » Journal of Immunology 148, no 6 (15 mars 1992) : 1797–803. http://dx.doi.org/10.4049/jimmunol.148.6.1797.
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Abstract The growth of a human B lymphoma cell line B104, an experimental model for mature B cells, was inhibited by ionomycin but not 12-O-tetradecanoylphorbol-13-acetate (TPA). Ionomycin inhibited B104 cells from entering into the M phase of the cell cycle without affecting DNA synthesis. The inhibition of cell division of B104 cells by ionomycin occurred within 24 h after stimulation. Because such a mode of action resembles that of anti-IgM antibodies, signals transduced by Ca2+ may be responsible for the inhibition of cell division of B104 cells by anti-IgM antibodies. Indeed, EGTA suppressed the inhibition of cell division of B104 cells caused not only by ionomycin, but also by anti-IgM antibody. Although TPA itself did not have any ability to promote the growth of B104 cells, it could cancel the inhibition of cell division of B104 cells by ionomycin and increase the proportion of B104 cells entering into the M phase of the cell cycle. Staphylococcus aureus Cowan I causes the greatest proliferation of normal human peripheral blood B cells during the period from 48 to 72 h after stimulation. When ionomycin was added to S. aureus Cowan I-stimulated peripheral blood B cells at 48 h of culture, it inhibited cell division during this period without affecting DNA synthesis. In the presence of TPA, this activity of ionomycin was suppressed, and the proportion of M-phase cells increased. These results suggest that cell division of mature B cells is regulated by the signals mediated by Ca2+ and protein kinase C in a mode quite different from that of regulation of DNA synthesis.
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Fischer, Jan, et Simon Guy. « Re-interpreting Regulations : Architects as Intermediaries for Low-carbon Buildings ». Urban Studies 46, no 12 (16 octobre 2009) : 2577–94. http://dx.doi.org/10.1177/0042098009344228.
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Regulations are highly influential in shaping urban places and architectural form. This paper investigates the impact of changing regulation on the working practices of architects. First, it outlines how the building regulations have grown in scope and complexity, especially with regard to energy regulations. Secondly, the relationship of regulation and design is explored, showing a shift from a dialectic of constraint and autonomy to one of interpretation of pathways. This is partly linked to performance-based regulation and weak state enforcement. Thirdly, the response of architects to this emerging mode of design is identified. The division of labour in the design process changes, with the architect focusing increasingly on intermediation. Finally, opportunities and threats to architects and their role are examined.
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Lei, Jinzhi, Simon A. Levin et Qing Nie. « Mathematical model of adult stem cell regeneration with cross-talk between genetic and epigenetic regulation ». Proceedings of the National Academy of Sciences 111, no 10 (5 février 2014) : E880—E887. http://dx.doi.org/10.1073/pnas.1324267111.
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Adult stem cells, which exist throughout the body, multiply by cell division to replenish dying cells or to promote regeneration to repair damaged tissues. To perform these functions during the lifetime of organs or tissues, stem cells need to maintain their populations in a faithful distribution of their epigenetic states, which are susceptible to stochastic fluctuations during each cell division, unexpected injury, and potential genetic mutations that occur during many cell divisions. However, it remains unclear how the three processes of differentiation, proliferation, and apoptosis in regulating stem cells collectively manage these challenging tasks. Here, without considering molecular details, we propose a genetic optimal control model for adult stem cell regeneration that includes the three fundamental processes, along with cell division and adaptation based on differential fitnesses of phenotypes. In the model, stem cells with a distribution of epigenetic states are required to maximize expected performance after each cell division. We show that heterogeneous proliferation that depends on the epigenetic states of stem cells can improve the maintenance of stem cell distributions to create balanced populations. A control strategy during each cell division leads to a feedback mechanism involving heterogeneous proliferation that can accelerate regeneration with less fluctuation in the stem cell population. When mutation is allowed, apoptosis evolves to maximize the performance during homeostasis after multiple cell divisions. The overall results highlight the importance of cross-talk between genetic and epigenetic regulation and the performance objectives during homeostasis in shaping a desirable heterogeneous distribution of stem cells in epigenetic states.
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Han, Dongchu, et Mianfang Liu. « How Does the Digital Economy Empower Green Development ? From the Perspective of the Division of Labor in New Classical Economics ». Sustainability 14, no 23 (26 novembre 2022) : 15740. http://dx.doi.org/10.3390/su142315740.
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The rise of the digital economy provides an alternative path for global green development. On the basis of analyzing the connotations of green development, digital economy and division of labor, this paper studies the theoretical mechanisms of the digital economy empowering green development; this is based on the division of labor thought of as the new classical economics. From the research results, it can be seen that the digital economy, through technological change, is conducive to the improvement of transaction efficiency and the evolution of the division of labor model. Under the dual role of the government’s green system and the market regulation mechanism, it promotes the transaction from the “black division of labor” mode to the “green division of labor” mode, thereby empowering green development. The impact of the digital economy on the level of green development is not single linear. This paper creatively analyzes the theoretical mechanisms of the digital economy empowering green development, from the perspective of the division of labor. These research results have good theoretical value and practical significance for promoting the sustainable development of the global economy.
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Ali Azam Khan, Md, et Mohammad Ali Choudhury. « Efficient Voltage Regulation with Modified Hybrid SEPIC DC-DC-Converter ». MATEC Web of Conferences 160 (2018) : 02004. http://dx.doi.org/10.1051/matecconf/201816002004.
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Switch mode dc-dc converters are attractive for their small size, ease of control and efficient power conversion. Output voltage is regulated by duty cycle control of semiconductor switch of switch mode dc-dc converters. The voltage gain and efficiency of practical switching regulators deviate from ideal values at extreme duty cycles. Also, desired gain /attenuation is not achievable at high/low duty cycles. In applications where high gain or high attenuation of voltage is desired with acceptable energy conversion efficiency, hybrid dc-dc switching converters are used. Hybrid dc-dc converters are combination of voltage multiplier/division circuit with appropriate SMPS circuits. By incorporating voltage multiplier/division cell with conventional SEPIC converters, desired voltage gain (either very low or very high) may be achieved at acceptable energy conversion efficiency. In the present work with an aim to attain very high voltage gain by conventional SEPIC topologies, a new voltage multiplier cell consisting of multiple inductors and diodes is proposed.
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Sakai, Satoshi, Nobumichi Ohoka, Kikuo Onozaki, Masatoshi Kitagawa, Makoto Nakanishi et Hidetoshi Hayashi. « Dual Mode of Regulation of Cell Division Cycle 25 A Protein by TRB3 ». Biological & ; Pharmaceutical Bulletin 33, no 7 (2010) : 1112–16. http://dx.doi.org/10.1248/bpb.33.1112.
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Bhargava, Pushpa M., et Sushil A. Chandani. « Regulation of cell division and malignant transformation ». Bioscience Reports 8, no 6 (1 décembre 1988) : 519–29. http://dx.doi.org/10.1007/bf01117330.
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The problem of regulation of cell division is essentially a problem of understanding regulation of transition from the resting state of a cell to the dividing state and vice versa. In malignancy the ability to revert back to a normal resting state is impaired. A model is presented which attempts to explain the control of the above transitions through control of uptake of essential nutrients by a transport-inhibitory protein. Experimental evidence in favour of the model is given.
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Tie, Warwick. « The ‘Correction’ of Community Crime Control : A Legal-Pluralist Interpretation ». Australian & ; New Zealand Journal of Criminology 29, no 3 (décembre 1996) : 282–98. http://dx.doi.org/10.1177/000486589602900306.
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The New Zealand Corrections Division has historically used the voluntary social work sector as a means of regulating criminality ‘at a distance’. Shifts in the modes through which the Division has related to the voluntary sector are analyzed here using Santos' form of legal-pluralist theory. That theory suggests that innovative forms of legal regulation are created when divergent modes of law interpenetrate one another. These new modes of legal power then attempt to regulate sociality by constructing the subjectivity of those with which they interact. This article suggests that the Corrections Division is itself characterised by dual forms of subjectivity, namely communitarian and proceduralist. The tension between these has become evident as the Division has sought to inculcate a proceduralist subjectivity within the voluntary sector, so as to construct voluntary sector agencies as self-regulating subjects. The tension exists between the Division's need to use the voluntary sector as a means by which it can regulate criminality, and to construct and respect that sector as an autonomous entity. Moreover, the imposition of a proceduralist subjectivity, because it is an imposition, has the potential to diminish the ability of those agencies to control crime and/or to critique its social construction.
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Palani, Saravanan, Darius V. Köster, Tomoyuki Hatano, Anton Kamnev, Taishi Kanamaru, Holly R. Brooker, Juan Ramon Hernandez-Fernaud et al. « Phosphoregulation of tropomyosin is crucial for actin cable turnover and division site placement ». Journal of Cell Biology 218, no 11 (9 octobre 2019) : 3548–59. http://dx.doi.org/10.1083/jcb.201809089.
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Tropomyosin is a coiled-coil actin binding protein key to the stability of actin filaments. In muscle cells, tropomyosin is subject to calcium regulation, but its regulation in nonmuscle cells is not understood. Here, we provide evidence that the fission yeast tropomyosin, Cdc8, is regulated by phosphorylation of a serine residue. Failure of phosphorylation leads to an increased number and stability of actin cables and causes misplacement of the division site in certain genetic backgrounds. Phosphorylation of Cdc8 weakens its interaction with actin filaments. Furthermore, we show through in vitro reconstitution that phosphorylation-mediated release of Cdc8 from actin filaments facilitates access of the actin-severing protein Adf1 and subsequent filament disassembly. These studies establish that phosphorylation may be a key mode of regulation of nonmuscle tropomyosins, which in fission yeast controls actin filament stability and division site placement.
Thèses sur le sujet "Regulation of the mode of division"
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Mida, Baptiste. « Un nouveau rôle de CDKN1C dans le contrôle de la transition des modes de division au cours de la neurogenèse des vertébrés ». Electronic Thesis or Diss., Sorbonne université, 2023. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2023SORUS371.pdf.
Texte intégralRésumé :
Le système nerveux central des vertébrés est constitué d’un assemblage complexe de nombreux types cellulaires, qui se développent à partir d’un réservoir limité de cellules souches neuroépithéliales. Pendant la neurogenèse, la transition progressive du mode de division des cellules progénitrices de symétrique prolifératif (SYM - produisant deux progéniteurs) vers asymétrique neurogénique (ASYM - produisant un neurone et un progéniteur) contrôle l’équilibre entre croissance et différenciation. Certains travaux pionniers ont montré que les progéniteurs SYM et ASYM diffèrent au niveau transcriptomique, suggérant que cette transition de SYM vers ASYM est placée sous un contrôle génétique spécifique. Par exemple, l’expression du facteur de transcription Tis21 est initiée dans les progéniteurs neuraux lors de la transition d’un mode de division SYM vers ASYM. Mon projet de thèse a eu pour objectif d’identifier de nouveaux acteurs et régulateurs de la transition SYM vers ASYM, et de valider fonctionnellement le rôle de ces candidats dans la régulation de cette transition. A travers l’analyse de données de RNA-seq à l’échelle cellule-unique provenant de tubes neuraux d’embryons de poulet et souris en développement, j’ai identifié en partenariat avec une équipe de bio-informaticiens (Morgane Thomas-Chollier, Nathalie Lehmann, IBENS) plusieurs gènes candidats à la régulation de la transition du mode de division, selon 2 critères : 1) l’expression différentielle du gène entre progéniteurs Tis21-positifs et négatifs et 2) un profil d’expression pseudo-temporel similaire à celui de Tis21 au cours de la neurogenèse. Parmi ces gènes, je me suis focalisé sur l’étude de CDKN1C (p57Kip2) qui jusqu’à présent avait été décrit principalement comme un régulateur négatif du cycle cellulaire. Mes travaux ont montré l’expression progressive de l’ARNm de CDKN1C dans la région ventrale du tube neural embryonnaire de poulet en développement, suggérant fortement une expression de CDKN1C dans les progéniteurs. J’ai également montré que la perte de fonction in vivo de CDKN1C (via shRNA) diminue la neurogenèse à l’échelle tissulaire, et favorise la prolifération des progéniteurs neuraux. L’exploration de ce phénotype a montré que les progéniteurs présentant une expression diminuée de CDKN1C ont une durée moyenne de cycle cellulaire plus courte, notamment due à une réduction de la durée de la phase G1, comparée à celle des progéniteurs sauvages. A travers une analyse clonale de la descendance de progéniteurs, j’ai ensuite montré que la diminution de l’expression de CDKN1C dans ces progéniteurs favorisait le mode de division SYM. Enfin, dans le but de déterminer si l’effet de CDKN1C sur le mode de division dépendait de son rôle régulateur du cycle cellulaire, et en particulier de la durée de G1, j’ai combiné une diminution d’expression de CDKN1C à une diminution de l’expression de la Cycline D1, qui devrait quant à elle allonger la durée de G1. Cette perte de fonction combinée permet de restaurer le phénotype observé après la diminution seule de CDKN1C, à l’échelle tissulaire et cellulaire, indiquant que le rôle de CDKN1C dans le contrôle du mode de division semble s’effectuer principalement à travers son rôle de régulateur négatif du cycle cellulaire. Dans l'ensemble, mon projet suggère un nouveau rôle de CDKN1C dans la régulation de la transition SYM-ASYM, et contribue à élucider les mécanismes fondamentaux qui régulent cette transition et donc l'équilibre entre prolifération et différenciation dans les progéniteurs neuraux au cours de la neurogenèseThe vertebrate central nervous system (CNS) is produced from a limited reservoir of neuroepithelial stem cells, which initially amplify through symmetric proliferative divisions (SYM) in which one progenitor produces two progenitors. Progressively, progenitors engage in an asymmetric neurogenic mode of division (ASYM), producing one progenitor and one neuron. Finally, symmetric terminal divisions (TERM) produce two neurons. The fine regulation of these division patterns is crucial for proper brain development, and alteration of these processes can lead to excessive proliferation or, conversely, generate early differentiation into neurons. In the developing CNS, SYM, ASYM and TERM modes of division appear in a sequential order within cell clones, indicating that transitions between modes of division are definitive, and correspond to compartmentalized cell states. Moreover, some pioneering works have shown that SYM and ASYM progenitors differ at the molecular level, notably at the transcriptomic level, suggesting that this transition from SYM to ASYM is under a specific genetic control. For example, the expression of the transcription factor Tis21 begins in neural progenitors during the transition from a proliferative to a neurogenic mode of division. My thesis project aimed at identifying new actors and regulators of the SYM to ASYM transition, at the border between proliferation and differentiation, and to functionally validate the role of these candidates in the regulation of this transition. Through the analysis of single-cell RNA-seq data from neural tubes of developing chick and mouse embryos, I identified in partnership with a team of bioinformaticians (Morgane Thomas-Chollier, Nathalie Lehmann, IBENS) several candidate genes in the regulation of the transition of the mode of division, according to 2 criteria: 1) a differential gene expression between Tis21-positive and negative progenitors and 2) a pseudo-temporal expression profile similar to the one of Tis21 during neurogenesis. Among these genes, I focused on the study of CDKN1C (p57Kip2) which until now had been described mainly as a negative regulator of the cell cycle. My work showed the progressive expression of CDKN1C mRNA in the ventral region of the developing chick embryonic neural tube, strongly suggesting the expression of CDKN1C in progenitors. I also showed that in vivo loss of function of CDKN1C (via shRNA) unfavors neurogenesis at the tissue level, and promotes neural progenitor proliferation. Exploration of this phenotype showed that progenitors with decreased CDKN1C expression have a shorter cell cycle duration on average, notably due to a reduction in the duration of the G1 phase, compared to wild-type progenitors. Through clonal analysis of the progenitors’ progeny, I then showed that decreased CDKN1C expression in progenitors favoured the SYM mode of division. Finally, in order to determine whether the effect of CDKN1C on the mode of division was dependent on its role in the cell cycle, I sought to counterbalance the decrease in G1 duration observed upon CDKN1C loss-of-function. To do so, I decreased the expression of Cyclin D1 in order to lengthen the duration of G1. The combined loss of function of CDKN1C and Cyclin D1 shows an almost complete rescue of the phenotype generated by the decrease in CDKN1C alone, at both the tissue and cellular levels, indicating that the role of CDKN1C in controlling the division mode seems to be directed mainly through its role as a negative regulator of the cell cycle. Overall, my project suggests a novel role for CDKN1C in the regulation of the SYM-ASYM transition, and contributes to elucidate the fundamental mechanisms that regulate this transition and thus the balance between proliferation and differentiation in neural progenitors during neurogenesis
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Šćepanović, Danilo (Danilo R. ). « A model of sinoatrial node cell regulation by the autonomic nervous system ». Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/68457.
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Thesis (Ph. D.)--Harvard-MIT Division of Health Sciences and Technology, 2011.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 243-260).
The primary function of the heart is to pump blood at a sufficient rate to ensure perfusion of all the organs. This vital task is achieved in large part by controlling the rate of cardiac contractions, which are initiated by cells in the sinoatrial node, the "pacemaker" of the heart. The oscillation rate of these spontaneously active cells is tightly regulated by the sympathetic and parasympathetic branches of the autonomic nervous system. Our understanding of sinoatrial node cell function has been greatly advanced by experimental and modeling efforts that quantitatively describe the numerous ionic currents responsible for the cell's spontaneous depolarization and generation of the action potential. Several models have also explored the effect of sympathetic and parasympathetic activity on specific ion channels and have reproduced the classic slowing and acceleration phenomena. However, a complete model of this interaction does not exist: current models lack the ability to simulate simultaneous sympathetic and parasympathetic activation or to reproduce heart rate dynamics in response to time-varying autonomic inputs. We addressed this need by constructing a bottom-up model of sinoatrial node cell regulation by the autonomic nervous system, with a focus on reproducing the full range of heart rates observed under simultaneous sympathetic and parasympathetic nerve stimulation, as well as the dynamic heart rate response to steps in sympathetic or parasympathetic stimulation rate. In constructing our model, we consolidate a large body of experimental data in a consistent mathematical framework. The model comprises 57 nonlinear coupled ordinary differential equations based on first principles and the current mechanistic understanding of the component reactions, fits well all the experimental data used to build the model, and reproduces high-level features of the system that were not explicitly fit when building the model. The detailed nature of the model also allows numerous conclusions to be drawn about the mechanisms of heart rate control. A better understanding of these mechanisms in health and disease may enable the development of better diagnostics for cardiovascular disease and more targeted drug design. We also identified a number of limitations in the present model that can be refined through further experimental and numerical efforts.
by Danilo Šćepanović.
Ph.D.
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Jenkins, Jesse D. (Jesse David). « Economic regulation of electricity distribution utilities under high penetration of distributed energy resources : applying an incentive compatible menu of contracts, reference network model and uncertainty mechanisms ». Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/90052.
Texte intégralRésumé :
Thesis: S.M. in Technology and Policy, Massachusetts Institute of Technology, Engineering Systems Division, Technology and Policy Program, 2014.Cataloged from PDF version of thesis.
Includes bibliographical references.
Ongoing changes in the use and management of electricity distribution systems - including the proliferation of distributed energy resources, smart grid technologies (i.e., advanced power electronics and information and communication technologies) and active system management techniques - present new challenges for the economic regulation of electricity distribution utilities. In particular, regulators are likely to face increased uncertainty regarding the evolution of network uses and the efficient cost of network investments and maintenance, as well as an increased informational disadvantage vis-a-vis the regulated utility. These challenges are especially important for regulatory approaches that establish some share of the utility's allowed revenues ex ante (e.g., incentive regulation, also known as revenue or price cap regulation, RPI-X, performance-based regulation, or output-based regulation). This thesis proposes a novel process for establishing the allowed revenues of an electricity distribution utility and demonstrates its application as a practical solution to the imminent regulatory challenges discussed above. The proposed method is a new combination of three established regulatory tools: an engineering-based reference network model (RNM) for forward-looking benchmarking of efficient network expenditures; an incentive compatible menu of contracts to elicit accurate forecasts from the utility and create incentives for cost saving efficiency efforts; and ex post automatic adjustment mechanisms, or "delta factors," to accommodate uncertainty in the evolution of network use and minimize forecast error. Chapter 1 reviews the theoretical economic foundations of the regulation of network monopolies, identifies emerging challenges in the regulation of electricity distribution companies, and introduces the proposed regulatory method. Chapter 2 describes the simulation of a realistic, large-scale urban distribution network used to demonstrate the novel regulatory process proposed in this thesis. Chapter 3 uses the simulated distribution network to demonstrate, step-by-step, the practical implementation of the novel regulatory process, evaluates its performance, and summarizes the advantages for the economic regulation of electricity distribution utilities under increasing penetration of distributed energy resources.
by Jesse D. Jenkins.
S.M. in Technology and Policy
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Bai, Neng. « Mode-Division Multiplexed Transmission in Few-mode Fibers ». Doctoral diss., University of Central Florida, 2013. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5761.
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As a promising candidate to break the single-mode fiber capacity limit, mode-division multiplexing (MDM) explores the spatial dimension to increase transmission capacity in fiber-optic communication. Two linear impairments, namely loss and multimode interference, present fundamental challenges to implementing MDM. In this dissertation, techniques to resolve these two issues are presented. To de-multiplex signals subject to multimode interference in MDM, Multiple-Input-Multiple-Output (MIMO) processing using adaptive frequency-domain equalization (FDE) is proposed and investigated. Both simulations and experiments validate that FDE can reduce the algorithmic complexity significantly in comparison with the conventional time-domain equalization (TDE) while achieving similar performance as TDE. To further improve the performance of FDE, two modifications on traditional FDE algorithm are demonstrated. i) normalized adaptive FDE is applied to increase the convergence speed by 5 times; ii) master-slave carrier recovery is proposed to reduce the algorithmic complexity of phase estimation by number of modes. Although FDE can reduce the computational complexity of the MIMO processing, due to large mode group delay (MGD) of FMF link and block processing, the algorithm still requires enormous memory and high hardware complexity. In order to reduce the required tap length (RTL) of the equalizer, differential mode group delay compensated fiber (DMGDC) has been proposed. In this dissertation, the analytical expression for RTL is derived for DMGDC systems under the weak mode coupling assumption. Instead of depending on the overall MGD of the link in DMGD uncompensated (DMGDUC) systems, the RTL of DMGDC systems depend on the MGD of a single DMGDC fiber section. The theoretical and numerical results suggest that by using small compensation step-size, the RTL of DMGDC link can be reduced by 2 orders of magnitude compared to DMGDUC link. To compensate the loss of different modes, multimode EDFAs are presented with re-configurable multimode pumps. By tuning the mode content of the multimode pump, mode-dependent gain (MDG) can be controlled and equalized. A proto-type FM-EDFA which could support 2 LP modes was constructed. The experimental results show that by using high order mode pumps, the modal gain difference can be reduced. By applying both multimode EDFA and equalization techniques, 26.4Tb/s MDM-WDM transmission was successfully demonstrated. A brief summary and several possible future research directions conclude this dissertation.Ph.D.
Doctorate
Optics and Photonics
Optics and Photonics
Optics
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Carpenter, Joel Anthony. « Holographic mode division multiplexing in optical fibres ». Thesis, University of Cambridge, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.610803.
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Spanoudis, Catherine M. « Cell Division Regulation in Staphylococcus aureus ». Scholar Commons, 2017. http://scholarcommons.usf.edu/etd/7090.
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Cell division is a fundamental biological process that occurs in all kingdoms of life. Our understanding of cell division in bacteria stems from studies in the rod-shaped model organisms: Gram-negative Escherichia coli and Gram-positive Bacillus subtilis. The molecular underpinnings of cell division regulation in non-rod-shaped bacteria remain to be studied in detail. Rod-shaped bacteria possess many positive and negative regulatory proteins that are essential to the proper placement of the division septa and ultimately the production of two identical daughter cells, many of which are absent in cocci. Given that essential cell division proteins are attractive antibacterial drug targets, it is imperative for us to identify key cell division factors especially in pathogens, to help counter the emergence of multi-drug resistance. In Staphylococcus aureus, a spherical Gram-positive opportunistic pathogen that causes a range of diseases from minor skin infections to life-threatening sepsis, we have identified the role of an essential protein, GpsB, in the regulation of cell division. We discovered that GpsB preferentially localizes to cell division sites and that overproduction of GpsB results in cell enlargement typical of FtsZ inhibition, while depletion of GpsB results in cell lysis and nucleoid-less minicell formation. The identification of GpsB’s interaction partners will allow us to understand the molecular mechanism by which GpsB regulates cell division.
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Kirby, Melissa Jane. « Regulation of sugar beet cell division ». Thesis, De Montfort University, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.391029.
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Dewar, Susan J. « Cell division in Escherichia coli : the expression and regulation of division genes ». Thesis, University of Edinburgh, 1988. http://hdl.handle.net/1842/13636.
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The four essential cell division genes ftsQ, ftsA, ftsZ, and envA are arranged sequentially within a large cluster of genes required for cell envelope growth and form. The bacteriophage λJFL100 carries the 1.8 kilobase EcoR1-HindIII chromosomal restriction fragment which spans the ftsQ and part of ftsA coding sequences. This fragment contains at least two promoters; one within ftsQ is required for the expression of ftsA and one within ftsA is required for expression of ftsZ. The fts fragment is cloned upstream of a lacZ gene so that transcription originating from within the fragment leads to the production of β-galactosidase. Expression from the fts promoters in cells lysogenic for the phage is shown to be derepressed in the absence of FtsA protein. The results presented here suggest that transcription from these promoters is linked to the cell's periodic requirement for FtsA protein during septum formation. The exact positions of the promoters within the group are not yet known although their approximate locations have been determined by promoter assay and sequence analysis. An attempt has been made to define the position of the ftsA promoter more precisely by in-vitro transcription from short, defined templates and by the sequential deletion of ftsQ. Serial deletion through ftsQ has revealed what appears to be a complex upstream regulatory region, reminiscent of a eukaryotic enhancer element, which influences the expression of ftsA. A model is presented for the transcriptional control of ftsA expression.
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Federici, Fernán. « Hormonal regulation of cell division in roots ». Thesis, University of Cambridge, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.608578.
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Benyahya, Kaoutar. « Mode group division multiplexing for short reach optical communications ». Thesis, Rennes 1, 2019. http://www.theses.fr/2019REN1S117.
Texte intégralRésumé :
La demande croissante du trafic de données sera alimentée par des technologies révolutionnaires telles que la réalité virtuelle (VR), la réalité augmentée (AR) et l’Internet des objets (IoT). Par conséquent, les réseaux optiques devraient répondre aux besoins de ces services en termes de débit, faible temps de réponse et grande fiabilité. En effet, les hauts débits représentent un besoin critique pour les systèmes de communication à fibre optique déployés dans les réseaux locaux ainsi que dans les centres de données. Pour ces deux applications, les systèmes basés sur la modulation d'intensité et la détection directe de cette dernière sont très attractifs en raison de leur faible coût et de leur compatibilité avec les applications à courte distance. Dans le cadre de cette thèse, nous répondons à la nécessité d’augmenter les débits pour les systèmes de communication optiques à courte distance basés sur le multiplexage de groupe de modes et la détection directe. Tout d'abord, nous visons à augmenter la capacité des fibres multimodes standard déjà déployées dans les réseaux locaux et à l’intérieur des centres de données où la distance est inférieure à 5 km. Deuxièmement, nous étendons notre solution aux applications avec des distances de déploiement plus longues telles que les connexions entre les centres de données. Dans les deux cas, les architectures des liens optiques, y compris les émetteurs, les récepteurs et les fibres optiques, sont analysées. De plus, les formats de modulation adaptés aux systèmes basés sur la détection directe tels que le format de modulation mono-porteuse 4-PAM et celui multi-porteuse DMT sont comparés dans le contexte de la transmission basée sur le multiplexage spatial. Nous avons démontré les avantages du multiplexage de groupes de modes combiné à la détection directe pour augmenter le débit transmit sur une seule fibre. Premièrement, 5 Tb / s ont été démontré sur 2,2 km de fibre multimode conventionnelle (OM2). Deuxièmement, un record de transmission de 14,5 Tb / s sur fibre OM2 est démontré au moment correspondant à sa réalisation. Enfin, 200 Gb / s sur 20 km de fibre faiblement multimode (FMF) a été démontré, ce qui étend les avantages du multiplexage par groupes de modes aux applications à longue distance par rapport aux réseaux LAN où la distance maximale est limitée à 5 kmThe ever-growing demand of data traffic will be fuelled by revolutionary technologies such as virtual reality (VR), augmented reality (AR) and Internet of things (IoT). Therefore, optical networks should support the requirements of these services in terms of high capacity, low latency and high reliability. In fact, large scale capacity is a critical need for fiber optic communication systems deployed in local area networks as well as in datacenters. For both applications, systems relying on intensity modulation and direct detection (IMDD) are highly demanded due to their low cost and compatibility with short range applications. In this thesis, we address the need of increasing the data rates for short reach optical communication systems based on mode group division multiplexing and direct detection schemes. Firstly, we focus on increasing the capacity of already deployed standard multimode fibers in local area networks and intra-datacenters communication where the distance is shorter than 5 km. Secondly, we extend our solution to longer reach applications such as inter-datacenter interconnects. In both cases, optical link architectures, including transmitters, receivers and the optical fibers are analysed. Moreover, modulation formats adapted to IMDD systems such as single carrier 4-PAM and multicarrier DMT are compared in the context of space division multiplexing transmission. In this work we demonstrated the achievable benefit of mode group multiplexing combined with IMDD schemes. First, 5 Tb/s has been achieved over 2.2 km of conventional multimode fiber (OM2). Secondly, transmission record at the corresponding time of its realization of 14.5 Tb/s over OM2 fiber is demonstrated. Finally, 200 Gb/s over 20 km of FMF has been achieved which extend the benefit of mode group multiplexing to longer reach applications compared to LAN and intra-datacenter where the maximum distance is limited to 5 km
Livres sur le sujet "Regulation of the mode of division"
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Kirby, Melissa Jane. Regulation of sugar beet cell division. Leicester : De Montfort University, 1995.
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Kazuhiro, Kohama, dir. Calcium inhibition : A new mode for CA²⁺ regulation. Tokyo : Japan Scientific Societies Press, 1992.
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O'Sullivan, Angela Mary. The regulation of division of higher plant cells. Leicester : Leicester Polytechnic, 1988.
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Bacterial growth and division : Biochemistry and regulation of prokaryotic and eukaryotic division cycles. San Diego : Academic Press, 1991.
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Thiyagarajan, Sathish. Mechanical Regulation in Cell Division and in Neurotransmitter Release. [New York, N.Y.?] : [publisher not identified], 2018.
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Illinois. Dept. of Professional Regulation. Licensing and Testing Division. Springfield, Ill : Illinois Dept. of Professional Regulation, 2000.
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French theories of regulation and conceptions of the international division of labour. New York, N.Y : St. Martin's Press, 1994.
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Renato, Baserga, dir. Biological regulation of cell proliferation. New York : Raven Press, 1986.
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Illinois. Dept. of Professional Regulation. Statewide Enforcement Division. Springfield, Ill : Illinois Dept. of Professional Regulation, 2000.
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Rose, Nancy L. Unionization and regulation : The division of rents in the trucking industry. Cambridge, Mass : Massachusetts Institute of Technology, Alfred P. Sloan School of Management, 1985.
Trouver le texte intégralChapitres de livres sur le sujet "Regulation of the mode of division"
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Lariviere, Patrick J., et Erin D. Goley. « Cell Division in Caulobacter crescentus : A Molecular-Scale Model ». Dans Cell Cycle Regulation and Development in Alphaproteobacteria, 101–41. Cham : Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-90621-4_4.
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Robles, Alfredo C. « Regulation in the Context of Regimes of Accumulation and Modes of Regulation ». Dans French Theories of Regulation and Conceptions of the International Division of Labour, 66–90. London : Palgrave Macmillan UK, 1994. http://dx.doi.org/10.1007/978-1-349-23260-4_5.
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Audigier, Isabelle. « Insurance Distribution Directive and Cross-Border Activities by Insurance Intermediaries in the EU ». Dans AIDA Europe Research Series on Insurance Law and Regulation, 3–30. Cham : Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-52738-9_1.
Texte intégralRésumé :
AbstractDespite the European passport granted to insurance intermediaries by the Insurance Mediation Directive (IMD) in 2002, the single market for insurance distribution remained very fragmented. In 2016, in order to promote the emergence of a genuine Single Market in insurance services, the Insurance Distribution Directive (IDD) introduced new rules on cross border insurance distribution and new division of competence between home and host Member State authorities. However, it failed to provide the necessary legal clarity on when an insurance intermediary is likely to be pursuing cross-border activities. This chapter will explore whether the IDD, together with the 2018 Decision of EIOPA’s board of Supervisors, have led or will lead to more market integration. This chapter also briefly analyses the possible impact of ‘Brexit’, that is, the leaving of the EU by the United Kingdom, on cross-border activities of insurance intermediaries.
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Rogosa, Morrison, Micah I. Krichevsky et Rita R. Colwell. « Mode of Cell Division ». Dans Springer Series in Microbiology, 97–98. New York, NY : Springer New York, 1986. http://dx.doi.org/10.1007/978-1-4612-4986-3_16.
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Budiarto, Bambang. « The Use of Non-cash Payment Methods During The National Economic Recovery ». Dans Proceedings of the 19th International Symposium on Management (INSYMA 2022), 305–10. Dordrecht : Atlantis Press International BV, 2022. http://dx.doi.org/10.2991/978-94-6463-008-4_40.
Texte intégralRésumé :
Abstract This study aims to determine the proportion ratio between people who have more income and sufficient income when using a non-cash payment method. The division of two groups of people’s income is based on The Regulation of the Minister of Manpower of the Republic of Indonesia No. 14 of 2020. People with more income have incomes above IDR 5,000,000 per month. People with sufficient income have incomes below IDR 5,000,000 per month. The government assists IDR 600,000 per month to people with sufficient income. By using α = 5%, based on the results of measuring proportion, it is known that Zvalue (1.64069) is smaller than Ztable (1.96) then the H0 value cannot be rejected. This means that the proportion ratio between people with more income and sufficient income when using a non-cash payment method is the same.
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Heim, Andreas, Beata Rymarczyk et Thomas U. Mayer. « Regulation of Cell Division ». Dans Advances in Experimental Medicine and Biology, 83–116. Cham : Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-46095-6_3.
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Marks, Friedrich, Ursula Klingmüller et Karin Müller-Decker. « Regulation of Cell Division ». Dans Cellular Signal Processing, 423–51. Second edition. | New York, NY : Garland Science, 2017. : Garland Science, 2017. http://dx.doi.org/10.4324/9781315165479-12.
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Rothfield, Lawrence I., et Jorge Garcia-Lara. « Cell Division ». Dans Regulation of Gene Expression in Escherichia coli, 547–69. Boston, MA : Springer US, 1996. http://dx.doi.org/10.1007/978-1-4684-8601-8_26.
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Bouget, François-Yves, Mickael Moulager et Florence Corellou. « Circadian Regulation of Cell Division ». Dans Plant Cell Monographs, 3–12. Berlin, Heidelberg : Springer Berlin Heidelberg, 2007. http://dx.doi.org/10.1007/7089_2007_119.
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Jung, Yongmin, Shaif-Ul Alam et David J. Richardson. « Optical Amplifiers for Mode Division Multiplexing ». Dans Handbook of Optical Fibers, 1–25. Singapore : Springer Singapore, 2018. http://dx.doi.org/10.1007/978-981-10-1477-2_49-1.
Texte intégralActes de conférences sur le sujet "Regulation of the mode of division"
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Sartain, John, Don Newburry, Mikko Pitkanen et Markku Ikonen. « 3-Way Catalyst Testing at VTT Energy ». Dans ASME 2003 Internal Combustion Engine Division Spring Technical Conference. ASMEDC, 2003. http://dx.doi.org/10.1115/ices2003-0592.
Texte intégralRésumé :
Emissions regulations on stationary, natural gas fired reciprocating engines are becoming increasingly tighter throughout the United States. In addition to lower NOx, CO and hydrocarbon limits, regulation of HAP (Hazardous Air Pollutant) emissions has become more prevalent. Rich burn (stoichiometric) natural gas engines are widely used in the oil and gas industry, as well as in distributed power generation. Due to the low oxygen content in the exhaust, these engines are suitable for 3-Way catalyst, which simultaneously reduces NOx and oxidizes CO and hydrocarbons. A series of 3-Way catalyst tests were conducted on a small natural gas engine at the VTT Technical Research Centre in Espoo, Finland. The overall goals of the testing were to determine the ability of various 3-Way catalysts to meet California emissions regulations and to gather data on HAPs emission reductions. The testing was carried out in two phases. In phase 1, several fresh catalysts were tested at the NOx/CO crossover point (i.e., the point where CO and NOx reduction percent is approximately equal) by using an air/fuel ratio controller to keep the exhaust oxygen level constant. Detailed emissions measurements of both regulated and unregulated emissions were taken. The measurements included NOx, CO, hydrocarbon species, CH2O, N2O, NH3, and H2. In phase 2, the effects of exhaust lambda variation on NOx and CO were studied in more detail, with aged catalyst. Also, different engine loads were tested to vary the space velocity and temperature. This paper describes the testing in more detail and presents some of the resulting data.
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Choi, Kyung-Wook, Ki-Bum Kim et Ki-Hyung Lee. « A Novel Cooling Strategy for a Diesel Engine to Improve Engine Power Efficiency and Emissions ». Dans ASME 2009 Internal Combustion Engine Division Fall Technical Conference. ASMEDC, 2009. http://dx.doi.org/10.1115/icef2009-14015.
Texte intégralRésumé :
Stringent regulations on CO2 emission causing greenhouse effect have drawn attention of automotive manufacturers to the diesel engine. The trend is to increase the engine power per liter, and research are being carried out to satisfy the regulation. In this paper, a new cooling strategy was proposed to control coolant more efficiently. Before carrying out a new cooling strategy, preliminary tests on the cooling components were performed. Measurement of metal temperature of the engine indicates that the conventional cooling system was designed inappropriately large to endure at high load conditions. Therefore several strategies were adapted to optimize the size of the conventional cooling system using an Electric Water Pump (EWP), Electric Valve (EV) and low temperature EGR cooler. A cooling system in a 2.7 liter Direct Injection Diesel Engine was modified for the purpose of this study, and the strategies were tested in a stationary test bench. As a result, emission and fuel consumption decreased in high coolant temperature and low coolant flow. Warm-up period in which THC and CO emissions were significant was shortened by controlling the coolant flow paths using EVs. An essential component in a diesel engine is an Exhaust gas recirculation (EGR) system that decreases combustion temperature and oxygen concentration resulting in a substantial reduction of NOx emission. The coolant circulates through the EGR cooler so that the EGR gas temperature could be dropped down, resulting in more efficient combustion. New cooling strategies were found to improve emissions and fuel economy of engines.
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« Design of Protection Measures for Deep Excavation of A New Underground Station Closely Adjacent to Viaduct of MRT System in Operation ». Dans The HKIE Geotechnical Division 41st Annual Seminar. AIJR Publisher, 2022. http://dx.doi.org/10.21467/proceedings.126.17.
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Due to limited land space in urban area, interchange MRT stations have to be constructed closely adjacent to existing system. Geotechnical design of new station has to ensure the safe operation of existing line. This paper presents a new underground MRT station located within 1 m of the foundation of viaduct of MRT line in operation with ridership more than 200,000 persons per day. Deformations inducted by deep excavation have to be controlled Deformations induced by deep excavation have to be controlled carefully to meet the rigorous limit values set up by Regulation of Building Restrictions along MRT Facilities. Sophisticated 2D/3D finite element (hereafter FEM) analyses have been performed to simulate the sequence of diaphragm wall constructions and Bottom-up deep excavation with pre-stress strut system.
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Chou, Hsoung-Wei, Chin-Cheng Huang, Bo-Yi Chen, Ru-Feng Liu et Hsien-Chou Lin. « Probabilistic Fracture Analysis for Boiling Water Reactor Pressure Vessels Subjected to Low Temperature Over-Pressure Event ». Dans ASME 2010 Pressure Vessels and Piping Division/K-PVP Conference. ASMEDC, 2010. http://dx.doi.org/10.1115/pvp2010-25196.
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With the development of probabilistic fracture mechanics (PFM) methods in recent years, the risk-informed approach has gradually been used to evaluate the structural integrity and reliability of the reactor pressure vessels (RPV) in many countries. For boiling water reactor (BWR) pressure vessels, it has been demonstrated that it is not necessary to perform the inservice inspections of beltline circumferential welds to maintain the required safety margins because their probability of failure is orders of magnitude less than that of beltline vertical welds, thus may well reduce the associated substantial cost and person-rem exposure. In Taiwan, however, the inservice inspections of shell welds still have to be performed every ten years per ASME Boiler and Pressure Vessel Code, Section XI inspection requirements for a BWR type Chinshan nuclear power station. In this work, a very conservative PFM model of FAVOR code consistent with that USNRC used for regulation is built with the plant specific parameters concerning the beltline shell welds of RPVs of Chinshan nuclear power station. Meanwhile, a hypothetical transient of low temperature over-pressure (LTOP) event which challenges the BWR RPV integrity most severely is also assumed as the loading condition for conducting the PFM analyses. Further, the effects of performance of inservice inspection are also studied to determine the benefit of the costly inspection effort. The computed low probability of failure indicates that the analyzed RPVs can provide sufficient reliability even without performing any inservice inspection on the circumferential welds. It also indicates that performing the inservice inspections can not promote the compensating level of safety significantly. Present results can be regarded as the risk incremental factors compared with the safety regulation requirements on RPV degradation and also be helpful for the regulation of BWR plants in Taiwan.
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Ciatti, Stephen, Swami Nathan Subramanian et Alison Ferris. « Effect of EGR in a Gasoline Operated Diesel Engine in LTC Mode ». Dans ASME 2012 Internal Combustion Engine Division Spring Technical Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/ices2012-81010.
Texte intégralRésumé :
Conventional combustion techniques struggle to meet the current emissions’ regulations while retaining high engine efficiency. Specifically in automotive diesel engines, oxides of nitrogen (NOx) and particulate matter (PM) emissions have limited the utilization of diesel fuel in compression ignition engines. By comparison, throttled, knock-limited conventional gasoline operated SI engines tend not to be fuel efficient. Advanced combustion systems that simultaneously address PM and NOx while retaining the high efficiency of modern diesel engines, are being developed around the globe [1]. One of the most difficult problems in the area of advanced combustion technology development is the control of combustion initiation [2] and retaining power density [3]. During the past several years, significant progress has been accomplished in reducing emissions of NOx and PM through strategies such as LTC/HCCI/PCCI/PPCI and other advanced combustion processes; however control of ignition and improving power density has suffered to some degree — advanced combustion engines tend to be limited to the 10 bar BMEP range and under [4]. Experimental investigations have been carried out on a light duty, DI, multi cylinder, diesel automotive engine. The engine is operated in low temperature combustion technology with 87 RON (Research Octane Number) fuel [7]. Using an Ignition Quality Test (IQT) device, the equivalent Cetane Number (CN) was measured to be 25. In the present work, various EGR rates are examined to determine the effect on the combustion, emissions and performance. Experiments were conducted at three different engine load/speed combinations that are part of General Motors’ reference points for vehicle operation. To reduce the complexity, boost pressure and injection pressure and timing were kept constant while EGR percentage and intake temperature were used as parameters in this study. The intake temperature was not truly independent, as it trended with EGR level, but based upon the boost level and the available EGR cooling, Intake Air Temperature (IAT) was kept in the range of 40–80 deg C. Additional cooling capacity will be added in future work in an effort to keep IAT more consistent. EGR rates have a detrimental effect on engine efficiencies at lower load while it appears to have little effect on efficiency at higher loads. A more significant effect at very low load appears to be higher intake temperatures (hot EGR) as opposed to the very slight decrease in oxygen concentration.
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Sun, Hui, Shouqi Yuan, Yin Luo et Bo Gong. « Characterization of Cavitation During Pump Operation Based on Hilbert-Huang Transform ». Dans ASME 2018 5th Joint US-European Fluids Engineering Division Summer Meeting. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/fedsm2018-83163.
Texte intégralRésumé :
Cavitation has negative influence on pump operation. In order to detect incipient cavitation effectively, experimental investigation was conducted to through acquisition of current and vibration signals during cavitation process. In this research, a centrifugal pump was modeled for research. The data was analyzed by HHT method. The results show that Torque oscillation resulted from unsteady flow during cavitation process could result in energy variation. Variation regulation of RMS of IMF in current signal is similar to that in axial vibration signal. But RMS of IMF in current signal is more sensitive to cavitation generation. It could be regarded as the indicator of incipient cavitation. RMS variation of IMF in base, radial, longitudinal vibration signals experiences an obvious increasing when cavitation gets severe. Such single variation regulation could be selected as the indicator of cavitation stage recognition. Hilbert-Huang transform is suitable for transient and non-stationary signal process. Time-frequency characteristics could be extracted from results of HHT process to reveal pump operation condition. The contents of current work could provide valuable references for further research on centrifugal pump operation detection.
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Zhou, Jianxu, Fulin Cai et Ming Hu. « Stability Analysis of Hydropower Stations With Complex Flow Patterns in the Tailrace Tunnel ». Dans ASME 2013 Fluids Engineering Division Summer Meeting. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/fedsm2013-16617.
Texte intégralRésumé :
For some special tailrace tunnels in the hydropower stations, including the changing top-altitude tailrace tunnel and the tailrace tunnel with downstream reused flat-ceiling diversion tunnel, during normal operation and hydraulic transients, the flow patterns inside are relatively complex mainly including the free-surface pressurized flow and partial free flow if the tail water level is lower than the top elevation of tunnel’s outlet. These complex flow patterns have obvious effect on system’s stability, and can not be simulated accurately by the traditional models. Therefore, a characteristic implicit model is introduced to simulate these complex flow patterns for further stability analysis. In some special cases, the characteristic implicit model also fails to completely simulate the mixed free-surface pressurized flow in the flat-ceiling tailrace tunnel. A new method is presented based on both experimental research and numerical simulation, and then, system’s stability is analyzed by compared with traditional ordinary boundary condition. The results indicate that, with different simulation models for the complex water flow in the tailrace tunnel, system’s dynamic characteristic can be actually revealed with the consideration of the effect of complex flow patterns in the tailrace tunnel on system’s stability and regulation performance.
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Qian, Jin-yuan, Cong-wei Hou, Zhi-xin Gao et Zhi-jiang Jin. « Transient Simulation on Dynamic Motion of Mobile Perforated Plate in Two Stage Spring Linked Perforated Plates ». Dans ASME 2018 5th Joint US-European Fluids Engineering Division Summer Meeting. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/fedsm2018-83156.
Texte intégralRésumé :
In a piping system, due to the sudden opening or closing of valves and pumps etc., pressure inside can be changed both rapidly and suddenly, which may cause water hammer, noise, vibration, and even damage the whole piping system seriously. Thus, to stabilize pressure in piping system under a target value is very important. In this paper, a novel pressure regulation component, two-stage spring linked perforated plate (TSP), is proposed, which is mainly made up of a fixed perforated plate, a mobile perforated plate and a spring to link them. To begin with, a transient numerical model of a TSP is established and the simulation results are compared with the theoretical formula for the purpose of validation. Then, its dynamic flow and pressure characteristics are investigated under typical inlet pressure and outlet pressure to present its advantage on pressure stabilization. Meanwhile, different pressure ratios from 1 to 2 are all investigated on dynamic motion of mobile perforated plate. Under different working conditions, the displacement during the dynamic motion at different flow time, the response time to reach the final stabilization, and pressure characteristics are all figured out. This work can be useful for the further design work on two-stage spring linked perforated plates and similar pressure regulation components.
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Xiong, Zhixiang, et Yin Luo. « Energy Saving Analysis and Improvement of Cooling Circulating Water System in M199 Technological Process ». Dans ASME 2017 Fluids Engineering Division Summer Meeting. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/fedsm2017-69513.
Texte intégralRésumé :
M199 is a kind of traditional drug fungicide, which is utilized widely in agriculture. The cooling circulating water system of such a production line consumes so much energy as to build cooling water supply model based on reaction vessel heat transfer mechanism and cooling requirement. The problems of the system is caused from improper pump selection, unreasonable condition adjustment methods, unscientific management, and difficulty in energy consumption evaluation and so on. In order to increase operation efficiency of the system and reduce the waste of energy, this paper surveyed the situation of equipment installation and M199 technological process, then compare the existing energy consumption with that under a variable frequency speed regulation to identify the space for energy saving, eventually complete the analysis of assessment of energy consumption in the whole system. Water supply system of variable pressure and flow is utilized under the premise of meeting the requirement of M199 technological process according to the pump affinity laws and by considering the energy-saving in the pump themselves and their systems so as to refurbish the system and realize the reduction of energy and production costs.
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Ren, Ning, Frances E. Lockwood, Ilya Piraner et Amit Gabale. « Modeling and Analysis of Mixed Lubrication in Automotive Valve Train ». Dans ASME 2014 Internal Combustion Engine Division Fall Technical Conference. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/icef2014-5475.
Texte intégralRésumé :
Environmental regulation and high fuel cost are among the leading driving forces behind the demand of energy efficient vehicles. Together with new engine hardware technologies, engine oil is expected to significantly contribute to improving vehicle fuel economy. New fuel-efficient engine oils are often formulated with advanced additives and low viscosity base oils. Understanding the lubrication performance at key engine components such as the cam and follower in valve train systems becomes critically important to ensure engine durability with the new fuel-efficient low viscosity oils. A full numerical mixed lubrication analysis of the cam and roller follower pair is conducted using the three dimensional line contact mixed elastohydrodynamic lubrication (EHL) model. The results show significant effects of surface roughness, topography, slide-to-roll ratio, and viscosity grade on lubricant film, contact pressure, and subsurface stress.
Rapports d'organisations sur le sujet "Regulation of the mode of division"
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Hooten, Christopher, et Carlo Pietrobelli. CMF in Review : 2006-2011. Inter-American Development Bank, février 2012. http://dx.doi.org/10.18235/0006906.
Texte intégralRésumé :
This paper presents a retrospective review of several key areas of work of the Capital Markets and Financial Institutions Division (CMF) of the Inter-American Development Bank. Presented with each chapter as an independent piece, the paper analyzes the operations portfolio of CMF from 2006 to 2011 drawing on a unique classification system developed in conjunction with the Division's internal Operations and Project Database. The goal of this database and paper is to move beyond the existing analytical frameworks of the bank to a more conceptual framework that looks at the fundamental goals and activities of each project. The paper draws useful lessons on projects and activities carried out in the areas of capital markets development and regulation, financial institutions development, banking regulation and supervision, financial inclusion, cluster development, and small and medium-sized enterprises development.
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Barg, Rivka, Erich Grotewold et Yechiam Salts. Regulation of Tomato Fruit Development by Interacting MYB Proteins. United States Department of Agriculture, janvier 2012. http://dx.doi.org/10.32747/2012.7592647.bard.
Texte intégralRésumé :
Background to the topic: Early tomato fruit development is executed via extensive cell divisions followed by cell expansion concomitantly with endoreduplication. The signals involved in activating the different modes of growth during fruit development are still inadequately understood. Addressing this developmental process, we identified SlFSM1 as a gene expressed specifically during the cell-division dependent stages of fruit development. SlFSM1 is the founder of a class of small plant specific proteins containing a divergent SANT/MYB domain (Barg et al 2005). Before initiating this project, we found that low ectopic over-expression (OEX) of SlFSM1 leads to a significant decrease in the final size of the cells in mature leaves and fruits, and the outer pericarp is substantially narrower, suggesting a role in determining cell size and shape. We also found the interacting partners of the Arabidopsis homologs of FSM1 (two, belonging to the same family), and cloned their tomato single homolog, which we named SlFSB1 (Fruit SANT/MYB–Binding1). SlFSB1 is a novel plant specific single MYB-like protein, which function was unknown. The present project aimed at elucidating the function and mode of action of these two single MYB proteins in regulating tomato fruit development. The specific objectives were: 1. Functional analysis of SlFSM1 and its interacting protein SlFSB1 in relation to fruit development. 2. Identification of the SlFSM1 and/or SlFSB1 cellular targets. The plan of work included: 1) Detailed phenotypic, histological and cellular analyses of plants ectopically expressing FSM1, and plants either ectopically over-expressing or silenced for FSB1. 2) Extensive SELEX analysis, which did not reveal any specific DNA target of SlFSM1 binding, hence the originally offered ChIP analysis was omitted. 3) Genome-wide transcriptional impact of gain- and loss- of SlFSM1 and SlFSB1 function by Affymetrix microarray analyses. This part is still in progress and therefore results are not reported, 4) Search for additional candidate partners of SlFSB1 revealed SlMYBI to be an alternative partner of FSB1, and 5) Study of the physical basis of the interaction between SlFSM1 and SlFSB1 and between FSB1 and MYBI. Major conclusions, solutions, achievements: We established that FSM1 negatively affects cell expansion, particularly of those cells with the highest potential to expand, such as the ones residing inner to the vascular bundles in the fruit pericarp. On the other hand, FSB1 which is expressed throughout fruit development acts as a positive regulator of cell expansion. It was also established that besides interacting with FSM1, FSB1 interacts also with the transcription factor MYBI, and that the formation of the FSB1-MYBI complex is competed by FSM1, which recognizes in FSB1 the same region as MYBI does. Based on these findings a model was developed explaining the role of this novel network of the three different MYB containing proteins FSM1/FSB1/MYBI in the control of tomato cell expansion, particularly during fruit development. In short, during early stages of fruit development (Phase II), the formation of the FSM1-FSB1 complex serves to restrict the expansion of the cells with the greatest expansion potential, those non-dividing cells residing in the inner mesocarp layers of the pericarp. Alternatively, during growth phase III, after transcription of FSM1 sharply declines, FSB1, possibly through complexing with the transcription factor MYBI serves as a positive regulator of the differential cell expansion which drives fruit enlargement during this phase. Additionally, a novel mechanism was revealed by which competing MYB-MYB interactions could participate in the control of gene expression. Implications, both scientific and agricultural: The demonstrated role of the FSM1/FSB1/MYBI complex in controlling differential cell growth in the developing tomato fruit highlights potential exploitations of these genes for improving fruit quality characteristics. Modulation of expression of these genes or their paralogs in other organs could serve to modify leaf and canopy architecture in various crops.
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Bloch, G., et H. S. Woodard. regulation of size related division of labor in a key pollinator and its impact on crop pollination efficacy. Israel : United States-Israel Binational Agricultural Research and Development Fund, 2021. http://dx.doi.org/10.32747/2021.8134168.bard.
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Despite the rapid increase in reliance on bumble bees for food production and security, there are many critical knowledge gaps in our understanding of bumble bee biology that limit their colony production, commercial management, and pollination services. Our project focuses on the social, endocrine, and molecular processes regulating body size in the two bumble bee species most important to agriculture: Bombus terrestris in Israel, and B. impatiens in the USA. Variation in body size underline both caste (queen/worker) differentiation and division of labor among workers (foragers are typically larger than nest bees), two hallmarks of insect sociality which are also crucial for the commercial rearing and crop pollination services of bumble bees. Our project has generated several fundamental new insights into the biology of bumble bees, which can be integrated into science-based management strategies for commercial pollination. Using transcriptomic and behavioral approaches we show that in spite of high flexibility, task performance (brood care or foraging) in bumble bee colonies is associated with physiological variation and differential brain gene expression and RNA editing patterns. We further showed that interactions between the brood, the queen, and the workers determine the developmental program of the larva. We identified two important periods. The first is a critical period during the first few days after hatching. Larvae fed by queens during this period develop over less days, are not likely to develop into gynes, and commonly reach a smaller ultimate body size compared to workers reared mostly or solely by workers. The facial exocrine (mandibular and hypopharangeal) glands are involved in this queen effect on larva development. The second period is important for determining the ultimate body size which is positively regulated by the number of tending workers. The presence of the queen during this stage has little, if at all, influence. We further show that stressors such as agrochemicals that interfere with foraging or brood care specific processes can compromise bumble bee colony development and their pollination performance. We also developed new technology (an RFID system) for automated collection of foraging trip data, for future deployment in agroecosystems. In spite of many similarities, our findings suggest important differences between the Eurasian model species (B. terrestris) and the North American model species (B. impatiens) that impact how management strategies translate across the two species. For example, there is a similar influence of the queen on offspring body size in both species, but this effect does not appear to be mediated by development time in B. impatiens as it is in B. terrestris. Taken together, our collaboration highlights the power of comparative work, to show that considerable differences that exist between these two key pollinator species, and in the organization of young bumble bee nests (wherein queens provide the majority of care and then transition away from brood care) relative to later stages of nest development.
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Ohad, Nir, et Robert Fischer. Regulation of Fertilization-Independent Endosperm Development by Polycomb Proteins. United States Department of Agriculture, janvier 2004. http://dx.doi.org/10.32747/2004.7695869.bard.
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Arabidopsis mutants that we have isolated, encode for fertilization-independent endosperm (fie), fertilization-independent seed2 (fis2) and medea (mea) genes, act in the female gametophyte and allow endosperm to develop without fertilization when mutated. We cloned the FIE and MEA genes and showed that they encode WD and SET domain polycomb (Pc G) proteins, respectively. Homologous proteins of FIE and MEA in other organisms are known to regulate gene transcription by modulating chromatin structure. Based on our results, we proposed a model whereby both FIE and MEA interact to suppress transcription of regulatory genes. These genes are transcribed only at proper developmental stages, as in the central cell of the female gametophyte after fertilization, thus activating endosperm development. To test our model, the following questions were addressed: What is the Composition and Function of the Polycomb Complex? Molecular, biochemical, genetic and genomic approaches were offered to identify members of the complex, analyze their interactions, and understand their function. What is the Temporal and Spatial Pattern of Polycomb Proteins Accumulation? The use of transgenic plants expressing tagged FIE and MEA polypeptides as well as specific antibodies were proposed to localize the endogenous polycomb complex. How is Polycomb Protein Activity Controlled? To understand the molecular mechanism controlling the accumulation of FIE protein, transgenic plants as well as molecular approaches were proposed to determine whether FIE is regulated at the translational or posttranslational levels. The objectives of our research program have been accomplished and the results obtained exceeded our expectation. Our results reveal that fie and mea mutations cause parent-of-origin effects on seed development by distinct mechanisms (Publication 1). Moreover our data show that FIE has additional functions besides controlling the development of the female gametophyte. Using transgenic lines in which FIE was not expressed or the protein level was reduced during different developmental stages enabled us for the first time to explore FIE function during sporophyte development (Publication 2 and 3). Our results are consistent with the hypothesis that FIE, a single copy gene in the Arabidopsis genome, represses multiple developmental pathways (i.e., endosperm, embryogenesis, shot formation and flowering). Furthermore, we identified FIE target genes, including key transcription factors known to promote flowering (AG and LFY) as well as shoot and leaf formation (KNAT1) (Publication 2 and 3), thus demonstrating that in plants, as in mammals and insects, PcG proteins control expression of homeobox genes. Using the Yeast two hybrid system and pull-down assays we demonstrated that FIE protein interact with MEA via the N-terminal region (Publication 1). Moreover, CURLY LEAF protein, an additional member of the SET domain family interacts with FIE as well. The overlapping expression patterns of FIE, with ether MEA or CLF and their common mutant phenotypes, demonstrate the versatility of FIE function. FIE association with different SET domain polycomb proteins, results in differential regulation of gene expression throughout the plant life cycle (Publication 3). In vitro interaction assays we have recently performed demonstrated that FIE interacts with the cell cycle regulatory component Retinobalsoma protein (pRb) (Publication 4). These results illuminate the potential mechanism by which FIE may restrain embryo sac central cell division, at least partly, through interaction with, and suppression of pRb-regulated genes. The results of this program generated new information about the initiation of reproductive development and expanded our understanding of how PcG proteins regulate developmental programs along the plant life cycle. The tools and information obtained in this program will lead to novel strategies which will allow to mange crop plants and to increase crop production.
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Jacobs, T. W. Regulation of cell division in higher plants. Office of Scientific and Technical Information (OSTI), janvier 1992. http://dx.doi.org/10.2172/5089653.
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Jacobs, T. W. Regulation of cell division in higher plants. Progress report. Office of Scientific and Technical Information (OSTI), juillet 1992. http://dx.doi.org/10.2172/10151324.
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Jacobs, T. Regulation of cell division in higher plants. Progress report, 1993. Office of Scientific and Technical Information (OSTI), septembre 1993. http://dx.doi.org/10.2172/10178901.
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Jacobs, Thomas W. Regulation of cell division in higher plants. Final technical report. Office of Scientific and Technical Information (OSTI), février 2000. http://dx.doi.org/10.2172/765959.
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Chen, Junping, Zach Adam et Arie Admon. The Role of FtsH11 Protease in Chloroplast Biogenesis and Maintenance at Elevated Temperatures in Model and Crop Plants. United States Department of Agriculture, mai 2013. http://dx.doi.org/10.32747/2013.7699845.bard.
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specific objectives of this proposal were to: 1) determine the location, topology, and oligomerization of FtsH11 protease; 2) identify the substrate/s of FtsH11 and the downstream components involved in maintaining thermostability of chloroplasts; 3) identify new elements involved in FtsH11 protease regulatory network related to HT adaptation processes in chloroplast; 4) Study the role of FtsH11 homologs from crop species in HT tolerance. Background to the topic: HT-tolerant varieties that maintain high photosynthetic efficiency at HT, and cope better with daily and seasonal temperature fluctuations are in great need to alleviate the effect of global warming on food production. Photosynthesis is a very complex process requiring accurate coordination of many complex systems and constant adjustments to the changing environments. Proteolytic activities mediated by various proteases in chloroplast are essential part of this process and critical for maintaining normal chloroplast functions under HT. However, little is known about mechanisms that contribute to adaptation of photosynthetic processes to HT. Our study has shown that a chloroplast-targeted Arabidopsis FtsH11 protease plays an essential and specific role in maintaining thermostability of thylakoids and normal photosynthesis at moderate HT. We hypothesized that FtsH11 homologs recently identified in other plant species might have roles similarly to that of AtFtsH1. Thus, dissecting the underlying mechanisms of FtsH11 in the adaptation mechanisms in chloroplasts to HT stress and other elements involved will aid our effort to produce more agricultural products in less favorable environments. Major conclusions, solutions, achievements - Identified the chloroplast inner envelope membrane localization of FtsH11. - Revealed a specific association of FtsH11 with the a and b subunits of CPN60. - Identified the involvement of ARC6, a protein coordinates chloroplast division machineries in plants, in FtsH11 mediated HT adaptation process in chloroplast. -Reveal possible association of a polyribonucleotide nucleotidyltransferase (cpPNPase), coded by At3G03710, with FtsH11 mediated HT adaptation process in chloroplast. - Mapped 4 additional loci in FtsH11 mediated HT adaptation network in chloroplast. - Demonstrated importance of the proteolytic activity of FtsH11 for thermotolerance, in addition to the ATPase activity. - Demonstrated a conserved role of plant FtsH11 proteases in chloroplast biogenesis and in maintaining structural and functional thermostability of chloroplast at elevated temperatures. Implications, both scientific and agricultural:Three different components interacting with FtsH11 were identified during the course of this study. At present, it is not known whether these proteins are directly involved in FtsH11mediated thermotolerance network in chloroplast and/or how these elements are interrelated. Studies aiming to connect the dot among biological functions of these networks are underway in both labs. Nevertheless, in bacteria where it was first studied, FtsH functions in heat shock response by regulating transcription level of σ32, a heat chock factor regulates HSPsexpression. FtsH also involves in control of biosynthesis of membrane components and quality control of membrane proteins etc. In plants, both Arc 6 and CPN60 identified in this study are essential in chloroplast division and developments as mutation of either one impairs chloroplast division in Arabidopsis. The facts that we have found the specific association of both α and β CPN60 with FtsH11 protein biochemically, the suppression/ enhancement of ftsh11 thermosensitive phenotype by arc6 /pnp allele genetically, implicate inter-connection of these networks via FtsH11 mediated network(s) in regulating the dynamic adaptation processes of chloroplast to temperature increases at transcriptional, translational and post-translational levels. The conserved role of FtsH11 proteases in maintaining thermostability of chloroplast at HT demonstrated here provides a foundation for improving crop photosynthetic performance at high temperatures.
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Morzinski, J. A., W. Gilmore et H. A. Hahn. Job task and functional analysis of the Division of Reactor Projects, office of Nuclear Reactor Regulation. Final report. Office of Scientific and Technical Information (OSTI), juillet 1998. http://dx.doi.org/10.2172/319712.
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