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Artykuły w czasopismach na temat "G switch"
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Gohil, S. "POS0626 MONEY MATTERS: ASSESSING THE VALUE OF THE ADALIMUMAB BIOSIMILAR SWITCH FOR RHEUMATOLOGY PATIENTS". Annals of the Rheumatic Diseases 80, Suppl 1 (19.05.2021): 551.2–551. http://dx.doi.org/10.1136/annrheumdis-2021-eular.2566.
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Background:The adalimumab biosimilar switch plan, actioned 2018-19 was one of the most complex of all biologic switches across several specialties. Non-medical switches are considered to ensure the best value medicines are prescribed for patients in line with NICE Technology Appraisals.Objectives:This 2 year follow up review explores the value of the switch for Rheumatology (R) patients in comparison to two other major specialisms; Dermatology (R) and Gastroenterology (G).Methods:403 homecare (HC) patients had been identified as eligible for switch to a citrate containing biosimilar (R;189, G;176, D;38) between April-December 2019. 35 hospital FP10 patients receiving the citrate-free originator biologic were also identified for switch to the citrate containing biosimilar and prescription processing via HC (R; 24, G; 9, D;2). Biosimilar switch information was communicated via patient letters/clinic reviews. FP10 patients also received remote pharmacist telephone support, as part of a PDSA (Plan, Do, Study, Act) quality improvement pilot. Data in regard to switch refusal, treatment cessation, withheld treatment and patient satisfaction ratings for pharmacist phonecalls (1 = unsatisfactory, 5=very satisfied) was documented.Results:235/403 HC patients successfully switched (R;99, G;107, D;29). 64/403 HC patients switched back to the originator (R;47, G;12; D;5). Of the 64 switch back HC patients; 52% = reported lack of efficacy; 27% = injection site pain and 21% = various other factors such as blepharitis, insomnia and hair loss. 38/403 HC patients refused the switch and remained on the originator biologic (R;11, G;27, D;0). 31/403 HC patients switched to an alternative biologic (R;19, G;9, D;3). 32/403 HC patients stopped treatment (R;13, G;19, D;0). Treatment was withheld for 3/403 HC patients (R;0, G;2, D;1). 100% of FP10 patients switched to HC. 31/35 FP10 patients switched to the biosimilar (R; 22, G; 7, D; 2). 3/31 patients switched back to the originator due to lack of efficacy or side effects. 4 patients refused the switch to biosimilar (R;3, G;1, D;0). 89% of patients were very satisfied with the pharmacist telephone support.Conclusion:In summary, 58% of all eligible HC patients switched in comparison to 89% of FP10 patients who received pharmacist telephone support; total cost saving following HC and FP10 switch = £270,000. Rheumatology demonstrated the least success in HC switching (52%) and the highest HC switch back figure (25%). Injection site pain and subjective lack of efficacy appear to be the main reasons for ongoing switch backs. The PDSA project demonstrates that a thorough pharmacist assessment of patient concerns in rationalising the use of a biologic agent versus biosimilar can be valuable for patients. Further cost effective adalimumab biosimilars have recently been launched. This seminal review emphasises the ongoing need for robust critical appraisals of biosimilars, with consideration for both clinical and cost effective parameters, before establishing their placement in treatment pathways.Acknowledgements:Mark Easter, UHCW and Interim Integrated Care System Chief Pharmacist, Hardeep Bagga, Deputy Chief Pharmacist, UHCW Pharmacy Homecare Team and UHCW Specialist Rheumatology, Gastroenterology and Dermatology Clinical Teams.Disclosure of Interests:None declared
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Mott, Helen R., i Darerca Owen. "Allostery and dynamics in small G proteins". Biochemical Society Transactions 46, nr 5 (9.10.2018): 1333–43. http://dx.doi.org/10.1042/bst20170569.
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The Ras family of small guanine nucleotide-binding proteins behave as molecular switches: they are switched off and inactive when bound to GDP but can be activated by GTP binding in response to signal transduction pathways. Early structural analysis showed that two regions of the protein, which change conformation depending on the nucleotide present, mediate this switch. A large number of X-ray, NMR and simulation studies have shown that this is an over-simplification. The switch regions themselves are highly dynamic and can exist in distinct sub-states in the GTP-bound form that have different affinities for other proteins. Furthermore, regions outside the switches have been found to be sensitive to the nucleotide state of the protein, indicating that allosteric change is more widespread than previously thought. Taken together, the accrued knowledge about small G protein structures, allostery and dynamics will be essential for the design and testing of the next generation of inhibitors, both orthosteric and allosteric, as well as for understanding their mode of action.
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Gohil, S. "AB1343-HPR A QUALITATIVE REVIEW ASSESSING THEMATIC OUTCOMES FROM THE PHARMACY-LED ADALIMUMAB BIOSIMILAR SWITCH PLAN ACROSS 3 SPECIALITIES; RHEUMATOLOGY, GASTROENTEROLOGY AND DERMATOLOGY AT UNIVERSITY HOSPITALS OF COVENTRY AND WARWICKSHIRE (UHCW)". Annals of the Rheumatic Diseases 79, Suppl 1 (czerwiec 2020): 1959.1–1960. http://dx.doi.org/10.1136/annrheumdis-2020-eular.3880.
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Background:The advent of biosimilars has heralded a new era for cost effective biologic prescribing in the NHS. As patents expire for originator biologics, less expensive versions are now widely available as biosimilars. Non-medical switches (for reasons unrelated to a patient’s health) ensure prescribing of best value medicines, and cost savings can be redirected to patient care.1This practice resonates with recommendations from Lord Carter’s 2016 report regarding reducing unwarranted variation in the NHS and adopting cost saving opportunities.2In 2018/19, following loss of patent exclusivity for the expensive adalimumab originator biologic, UHCW worked in accordance with national directives to drive forward one of the largest non-medical biosimilar switches.Objectives:This qualitative review aims to explore the success of the adalimumab biosimilar switch and key themes associated with switch backs/refusals across the Rheumatology (R), Gastroenterology (G) and Dermatology (D) specialities at UHCW.Methods:The switch plan occurred between April-December 2019. 403 patients (R;189, G;176, D; 38) were eligible for switch. Patients were informed of the plan in advance via a patient information leaflet/hospital clinic visits. Switch refusals, withheld treatments and cancellations were documented and patients were advised to contact the hospital pharmacy/clinical teams if they encountered any concerns, adverse effects or lack of efficacy post switch. The clinician would then advise on subsequent management.Results:During April-December 2019, 264/403 patients had been successfully switched (R;122, G;109, D;33). 33/403 patients switched back to the originator biologic (R;22, G;10; D;1). Of the 22 rheumatology switch back patients; 6 patients reported injection site pain and variably headache, fatigue, disease relapse, gastrointestinal (GI) upset, erythema; 10=reported lack of efficacy and variably influenza-type symptoms, relapse in associated psoriasis, difficulty in walking/sleeping, hair loss, excessive perspiration, facial cellulitis, foot drop and GI upset; 1=blepharitis;1=latex allergy before injection; 3=later declined switch; 1=damaged two devices and did not wish to continue biosimilar. Of the 10 gastroenterology switch back patients; 1=injection site pain; 2=lack of efficacy; 1=developed needle phobia; 1=latex allergy before injection; 1=switch detrimental to health; 2=unstable disease; 1=insomnia; 1=pregnancy. The 1 dermatology switch back patient reported injection site pain and bleeding.38/403 patients refused the switch and remained on the originator biologic (R;11, G;27, D;0). 29/403 patients had treatment cancellations and were switched to an alternative biologic (R;17, G;9, D;3). 32/403 patients stopped treatment (R;13, G;19, D;0). Treatment was withheld for 7/403 patients (R;4, G;2, D;1).Conclusion:The UHCW adalimumab biosimilar switch plan succeeded in switching a total of 66% of patients; thus an annual cost saving of £73,020. Injection site pain, most likely due to the biosimilar citrate content, and lack of efficacy according to patient perception and subsequent clinical review, were the most predominant causative themes for switch backs. Gastroenterology patients accounted for 71% (27/38) of the total switch refusals. Additional data regarding patient refusals, identifies future opportunities to improve patient counselling and drive further cost savings.References:[1]Azevedo V, et al. Biosimilars: considerations for clinical practice. Considerations in Medicine. 2017;1(1):13–8[2]Lord Carter of Coles. (2016) Operational productivity and performance in English NHS Acute Hospitals: Unwarranted variations [Online]Acknowledgments:Mark Easter, Chief Pharmacist, Hardeep Bagga, Deputy Chief Pharmacist, UHCW Pharmacy Homecare Team, UHCW Specialist Clinical Teams.Disclosure of Interests:None declared
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Sarma, Yadavalli V. S. "A G/o/G system with slow switch". Stochastic Analysis and Applications 7, nr 1 (styczeń 1989): 117–24. http://dx.doi.org/10.1080/07362998908809171.
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Chen, Wenguo, Rui Wang, Huiying Wang i Zhen Yang. "Design, Simulation, and Fabrication of a New Three-Axis Inertial Switch with a Triangular Movable Electrode Structure". Micromachines 14, nr 1 (30.12.2022): 94. http://dx.doi.org/10.3390/mi14010094.
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A new three-axis inertial switch is proposed. The triangle-structured movable electrode is designed to improve the inertial switch’s dynamic response performance, especially the movable electrode’s dynamic stability performance. The static mechanical analysis indicated that the displacement of the movable electrode to the fixed electrode in the sensitive direction is the minimum when the acceleration is applied to this designed inertial switch. The dynamic simulation analysis showed that the threshold of the designed inertial is about 235 g. The threshold in the non-sensitive direction is about 240 g, 270 g, 300 g, and 350 g when the directions of applied acceleration deviate 15°, 30°, 45°, and 60° from the sensitive direction, respectively. These results indicated that the designed inertial could resist the impact in non-sensitive directions and improve the stability in sensitive directions. The prototype of the inertial switch was fabricated and tested successfully. The testing results indicate that the threshold of the fabricated inertial switch is about 219 g. The test results verify the dynamic stability performance of the designed inertial switch.
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Ferrarelli, L. K. "A disease-causing G protein switch". Science 352, nr 6283 (14.04.2016): 304–6. http://dx.doi.org/10.1126/science.352.6283.304-r.
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Ghusinga, Khem Raj, Timothy C. Elston i Alan M. Jones. "Towards resolution of a paradox in plant G-protein signaling". Plant Physiology 188, nr 2 (16.11.2021): 807–15. http://dx.doi.org/10.1093/plphys/kiab534.
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Abstract G-proteins are molecular on–off switches that are involved in transmitting a variety of extracellular signals to their intracellular targets. In animal and yeast systems, the switch property is encoded through nucleotides: a GDP-bound state is the “off-state” and the GTP-bound state is the “on-state”. The G-protein cycle consists of the switch turning on through nucleotide exchange facilitated by a G-protein coupled receptor and the switch turning off through hydrolysis of GTP back to GDP, facilitated by a protein designated REGULATOR OF G SIGNALING 1 (RGS). In plants, G-protein signaling dramatically differs from that in animals and yeast. Despite stringent conservation of the nucleotide binding and catalytic structures over the 1.6 billion years that separate the evolution of plants and animals, genetic and biochemical data indicate that nucleotide exchange is less critical for this switch to operate in plants. Also, the loss of the single RGS protein in Arabidopsis (Arabidopsis thaliana) confers unexpectedly weaker phenotypes consistent with a diminished role for the G cycle, at least under static conditions. However, under dynamic conditions, genetic ablation of RGS in Arabidopsis results in a strong phenotype. We explore explanations to this conundrum by formulating a mathematical model that takes into account the accruing evidence for the indispensable role of phosphorylation in G-protein signaling in plants and that the G-protein cycle is needed to process dynamic signal inputs. We speculate that the plant G-protein cycle and its attendant components evolved to process dynamic signals through signaling modulation rather than through on–off, switch-like regulation of signaling. This so-called change detection may impart greater fitness for plants due to their sessility in a dynamic light, temperature, and pest environment.
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Nishimura, Shoichi, i Yong Jiang. "An M/G/l Vacation Model with Two Service Modes". Probability in the Engineering and Informational Sciences 9, nr 3 (lipiec 1995): 355–74. http://dx.doi.org/10.1017/s0269964800003922.
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Consider an M/G/1 type queueing system with two service modes: regular speed and high speed. The service rule is characterized by two switch-over levels nR and nH, where nR and nH are given integers with 0 ≤ nH < nR. The server switches from regular speed mode to high speed mode when the number of customers present at a service completion epoch is equal to or larger than nR and switches from high speed mode to regular speed mode when the number of customers present decreases to nH. A key feature of the model is that the server takes a vacation for setup operations before a new service mode is available. This paper derives for the general model an expression for the generating function of the equilibrium queue-length distribution in terms of the switch-over levels. Two unknown parameters appear in the generating functions. Using a recursive method, we solve these unknown parameters and obtain a computationally tractable algorithm for the steady-state probabilities.
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Wong, Wei. "A regulatory switch in obesity". Science 370, nr 6521 (3.12.2020): 1177.7–1178. http://dx.doi.org/10.1126/science.370.6521.1177-g.
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Deng, Jufeng, Dian Song i Shijie Su. "Highly Sensitive Inertial Micro-Switch for Achieving Adjustable Multi-Threshold Acceleration". Actuators 12, nr 2 (26.01.2023): 53. http://dx.doi.org/10.3390/act12020053.
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An inertial micro-switch with multi-threshold acceleration detection capability has been proposed, taking advantage of electromechanical coupling behavior. A mathematical model of electromechanical coupling behavior was established to display the dependence of highly sensitivity on pull-in characteristic and show the ability to detect threshold acceleration by controlling the voltage applied to the inertial micro-switch. The capability of sensitivity and detection that was described in mathematical model was implemented to occur at the inertial switch and showed agreement with that of a simulation. Inertia switches that were comprised of various microstructures with dimensions ranging 3.5 µm from 180 µm were manufactured by means of the micro-electro-mechanical system (MEMS) manufacturing process, and their functions were evaluated by a dropping system. The control method related to the manufacturing of inertial switches was obtained by analyzing the effect of the structural parameters of the inertial switch on threshold voltage and threshold acceleration, resulting in a relatively small error between simulation and experiment. The inertial micro-switch showed high sensitivity to achieving the pull-in effect at 30 V, sense multi-threshold acceleration ranging from 500 g to 2000 g in 2.46 ms and provided enough time for outputting the acceleration signal. Furthermore, the multi-threshold acceleration can be adjusted by controlling the voltage applied to inertial micro-switches. In addition, other functions of inertial micro-switches, such as lower residual stress, high recoverability, and repeatability, have been displayed.
Rozprawy doktorskie na temat "G switch"
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Cristillo, Anthony D. "Characterization of G¦o/G¦1 switch genes in cultured T lymphocytes". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ27819.pdf.
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Tashiro, Junko. "Palindromic but not G-rich sequences are targets of class switch recombination". Kyoto University, 2001. http://hdl.handle.net/2433/150571.
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Heximer, Scott Patrick. "Studies on two putative G¦0/G¦1 switch genes in human T-lymphocytes, RGS2/G0S8 and G0S24". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq20563.pdf.
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Greco, Maria Laura. "Conformational switch of oncogene promotorial sequences towards non-canonical DNA secondary structures". Doctoral thesis, Università degli studi di Padova, 2015. http://hdl.handle.net/11577/3424026.
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The folding of DNA molecule into non-canonical secondary structures has been shown to be implicated in many important biological processes which regulate cell proliferation and proteins expression. In particular one of these peculiar secondary structures, called G-quadruplex (G4), has been shown to potentially impair cancer development. G4 occurs along DNA sequences rich of consecutive guanines which can fold through Hoostein pairs by forming stacked planes of guanines tetrads. This conformation prevalently forms along the termini of chromosomes (telomeres) but also along the promoter sites of several oncogenes directly involved in many cancers. The G4 formation leads to an hindrance on DNA molecule which hinder the telomere elongation and transcription process. The result is a switching off of these mechanisms which are directly involved in cancer progression. Several factors can influence the G4 equilibria for example, saline conditions, temperature, pH, the binding with specific proteins as well as the presence of dehydrating cosolutes. Additionally, the overall structural feature of the G4 is strictly dependent upon the DNA sequence. As a results, different G4 can be identified inside the cells.
In this project, we focused on the conformational study of the promotorial regions of EGFR and BRAF oncogenes since, on these sites the existence of G4 putative forming regions was found. In particular, the sequences at positions -272, -37 of EGFR and -176 of BRAF from the transcription start site were analyzed. Indeed, no previous literature data were reported about the structural equilibria in solution of these sequences. We found that our tested sequences are actually able to fold into G4 by setting the most proper experimental conditions and also close to the intracellular physiological environment (KCl 150 mM, pH 7.5).
However, oncogenes are double stranded sequences and the folding of the complementary cytosine rich strand into i-motif (iM) can be involved in the switching off of gene transcription. Although, so far, no physiological evidence has been observed for i-motif conformation, here, we aimed to investigate also the cytosine rich strand conformation, to assess if this folding in the case of our sequences is compatible with the physiological conditions and if it can synergically works with the G4 to destabilize the double strand. Our data showed that in physiological condition the preferential form is represented by the double strand . However, some selected ligands showed to shift the DNA B-form toward the non canonical conformation. Indeed, here we implemented our work with the screening of two libraries of compounds in order to find a selective and efficient binder. We carried on the binding study of anthraquinones and naphthalene diimides derivatives, known to have the chemical features of efficient G4 binders. These ligands were first tested on different G4 templates, known to be validated models for G4 binding study, and their efficiency on G4 has been compared with the double strand. The most G4 selective derivatives were than investigated towards our oncogenic G4s. Although more work is required to identify a lead compound, we were able to demonstrate how the use of asymmetrical substitution pattern on a aromatic core can implement the selectivity among different G4s.
Finally, in order to map the occurrence of G4 conformation in vivo, we set up a novel technique which consists in an in vivo footprinting protocol. This work, performed at University of Mississippi, Oxford, MS (USA), under the supervision of Dr Tracy A. Brooks, should provide novel insight on the G4 formation in the cells according to their physiological and environmental conditionsMolti studi dimostrano che l’assunzione di strutture “non canoniche” da parte della molecola di DNA sia coinvolto in molti importanti processi biologici che regolano la proliferazione cellulare e l’espressione proteica. In particolare, è stata dimostrata l’implicazione di una di queste particolari strutture secondarie, chiamata G-quadruplex (G4), nel blocco della progressione del cancro. La struttura G4 è propria di sequenze di DNA ricche in guanine consecutive che assemblandosi tramite legami di Hoostein, formano piani di tetradi di guanine impilati tra loro. Questa particolare conformazione si forma prevalentemente lungo i tratti terminali dei cromosomi, i telomeri, ma anche lungo siti promotoriali di diversi oncogeni coinvolti in molti tipi di cancro. La formazione del G4 porta ad una sorta di ingombro sulla molecola di DNA che inibisce l’elongazione del telomero e i processi di trascrizione. Questo porta ad uno “spegnimento” di questi meccanismi che sono direttamente coinvolti nello sviluppo del cancro. Molti fattori possono influenzare gli equilibri delle conformazioni G4, per esempio, le condizioni saline, la temperatura, il pH, il legame con specifiche proteine, così come la presenza di cosoluti. Inoltre, la struttura globale del G4 é rigorosamente dipendente dalla sequenza oligonucleotidica. Pertanto, diverse strutture G4 possono essere identificate a livello cellulare. In questo progetto, è stato condotto uno studio conformazionale di regioni promotoriali degli oncogeni EGFR e BRAF, dal momento che, su questi oncogeni è stata riscontrata la presenza di regioni “G-rich” (ricche in guanine) potenzialmente in grado di assumere una struttura G4. In particolare, sono state analizzate le sequenze a partire dalle posizioni -272, -37 di EGFR e -176 di BRAF dal “transcription start site” (sito di inizio della trascrizione). Finora, non sono presenti dati in letteratura riguardanti la caratterizzazione strutturale di queste sequenze in soluzione. Con questo studio, è stata dimostrata la capacità delle suddette sequenze di assumere una conformazione G4 nelle idonee condizioni sperimentali e soprattutto in un ambiente che mimi quello fisiologico (150mM KCl e pH 7.5). Poiché gli oncogeni sono sequenze a doppio filamento, anche la conformazione i-motif assunta dal filamento complementare ricco in citosine (“C-rich”) può essere coinvolta nella regolazione del processo di trascrizione genica. Tuttavia, sinora non è stata riscontrata alcuna rilevanza fisiologica della conformazione i-motif. In questo lavoro, è stata caratterizzata anche la conformazione assunta dal filamento “C-rich”, in particolare se essa possa esistere in condizioni fisiologiche e se fosse in grado di destabilizzare la doppia elica insieme al G4. I dati ottenuti dimostrano che in condizioni fisiologiche la forma prevalente è il doppio filamento. Tuttavia, è stato dimostrato come alcuni ligandi siano in grado di spostare l’equilibrio del DNA dalla sua forma di doppia elica-B, verso le conformazioni non canoniche. È stato infatti condotto uno studio su due librerie di composti con lo scopo di evidenziare un composto selettivo ed efficace. Ci siamo focalizzati su derivati antrachinonici e di naftalendiimidi noti come efficaci ligandi per il G4. Questi composti sono stati prima testati su diversi templati G4, noti per essere dei modelli validati per lo studio di binding sul G4. Quindi la loro efficienza sul G4 è stata poi comparata a quella sul doppio filamento. I derivati più selettivi verso il G4 sono stati poi testati su G4 oncogenici. Sebbene una continuazione dello studio fosse necessaria per identificare un composto “lead”, con questo lavoro è stato dimostrato come l’uso di una sostituzione asimmetrica sull’anello aromatico possa implementare la selettività tra più G4. Infine, per identificare la formazione del G4 in vivo, è stata messa a punto una nuova tecnica che consiste in un protocollo di footprinting in vivo. Questo lavoro, svolto nell’Università del Mississippi, Oxford, MS (USA) sotto la supervisione della dr.ssa Tracy A. Brooks, dovrebbe fornire nuovi sviluppi per la formazione del G4 nelle cellule in accordo con le loro condizioni fisiologiche
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Sutherland, Caleb, Yunxi Cui, Hanbin Mao i Laurence H. Hurley. "A Mechanosensor Mechanism Controls the G-Quadruplex/i-Motif Molecular Switch in the MYC Promoter NHE III 1". AMER CHEMICAL SOC, 2016. http://hdl.handle.net/10150/621939.
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MYC is overexpressed in many different cancer types and is an intensively studied oncogene because of its contributions to tumorigenesis. The regulation of MYC is complex, and the NHE III1 and FUSE elements rely upon noncanonical DNA structures and transcriptionally induced negative superhelicity. In the NHE III1 only the G-quadruplex has been extensively studied, whereas the role of the i-motif, formed on the opposite C-rich strand, is much less understood. We demonstrate here that the i-motif is formed within the 4CT element and is recognized by hnRNP K, which leads to a low level of transcription activation. For maximal hnRNP K transcription activation, two additional cytosine runs, located seven bases downstream of the i-motif-forming region, are also required. To access these additional runs of cytosine, increased negative superhelicity is necessary, which leads to a thermodynamically stable complex between hnRNP K and the unfolded i-motif. We also demonstrate mutual exclusivity between the MYC G-quadruplex and i-motif, providing a rationale for a molecular switch mechanism driven by SP1-induced negative superhelicity, where relative hnRNP K and nucleolin expression shifts the equilibrium to the on or off state.
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Mirihana, Arachchilage Gayan S. "REGULATORY ROLES OF G-QUADRUPLEX IN microRNA PROCESSING AND mRNA TRANSLATION". Kent State University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=kent1469576783.
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Yamaoki, Yudai. "The development of intelligent ribozyme and RNA aptamer whose activities switch on in response to K⁺via quadruplex formation". Kyoto University, 2016. http://hdl.handle.net/2433/204592.
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Aouimeur, Walid. "Systèmes de mesure intégré sub-millimétrique en bande G (140-220 GHz) en technologie BiCMOS 55 nm". Thesis, Université Grenoble Alpes (ComUE), 2018. http://www.theses.fr/2018GREAT046.
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Les applications microélectroniques telles que les communications sans fil ou les radars nécessitent des traitements d’information avec des débits ou des résolutions de plus en plus élevés. Cela implique de travailler à des fréquences millimétriques voir sub-millimétriques. Grâce aux progrès des technologies silicium, des circuits intégrés travaillant dans les gammes de fréquences millimétriques émergent mais souffrent d'un manque de solution de caractérisation complète. Par exemple, il n’existe à ce jour aucun analyseur vectoriel de réseaux commercial qui soit capable de mesurer les paramètres S dans la bande G (140-220 GHz) en 4 ports. La caractérisation classique des circuits millimétriques en n ports (avec n>2) consiste alors à utiliser un analyseur vectoriel de réseaux 2 ports et à adapter les autres ports non utilisés à 50Ω. Par permutation circulaire, on arrive ainsi à extraire la matrice S d’un dispositif à n ports (avec n>2). Ce protocole de mesure est très long et délicat à mettre en place car il nécessite d’une part un investissement en appareil de mesure très couteux aux fréquences millimétriques et d’autre part de mettre en œuvre des méthodes de calibrage et de de-embedding précises et dédiées.Le travail développé dans le cadre de cette thèse a visé à intégrer dans la puce, des systèmes de caractérisation petits signaux (paramètres S) au plus près du Dispositif Sous Test (DST). Le fait d’être au plus près du DST permet de réduire les pertes d’insertion, de réduire l’amplitude des vecteurs d’erreurs et donc les erreurs résiduelles après calibrage. Par ailleurs, il est possible de mieux contrôler la puissance du signal envoyé et de considérer des méthodes de calibrage utilisant des charges intégrées, ce qui permet de réduire le temps de traitement et le cout. La technologie utilisée est la technologie SiGe BiCMOS 55 nm développée par la société STMicroelectronics, technologie particulièrement adaptée aux circuits en bande millimétrique. La solution développée dans cette thèse consiste à connecter le wafer avec des pointes de mesure qui amènent un signal hyperfréquence balayant le spectre 35-55 GHz. Une fois dans la puce, ce signal hyperfréquence est quadruplé en fréquence et amplifié afin d’atteindre des niveaux de puissance suffisant (bon rapport Signal/bruit) dans la bande G aux bornes du DST. Les paramètres de réflexion (S11 et S22) sont ensuite extraits grâce à deux coupleurs très directifs, placés sur l’entrée et la sortie du DST respectivement. Les sorties du coupleur sont ensuite ramenées en basse fréquence (0.5GHz < IF < 2.4 GHz) par l’intermédiaire de mélangeurs de fréquence.L’approche choisie est argumentée en se basant sur une étude des systèmes de mesures existant présentée dans la première partie de ce manuscrit. Puis la conception et la caractérisation de chacun des blocs composant le système sont détaillées : le quadrupleur de fréquence en bande G (constitué d’un doubleur de fréquence en bande W cascadé avec un doubleur de fréquence en bande G), le transfert switch en bande G permettant de commuter entre l’entrée et la sortie du DST, le coupleur directif à ondes lentes, les mélangeurs permettant de ramener les mesures en basse fréquence, etc…. Une fois tous les différents blocs présentés, le manuscrit aborde les deux systèmes de mesure conçus. Un premier système un port a été développé pour valider cette approche. Le second système conçu permet de mesurer un DST à deux ports (HBT). Ce second système conserve l’architecture hétérodyne du premier, intégrant en plus un transfert switch en bande G qui dirige le signal incident vers l’un des deux ports du DSTMicroelectronic applications such as wireless communications, radar or space detections require higher data rate resolutions, implying the use of millimeter wave and submillimeter frequencies. Thanks to the silicon technologies improvement, some microelectronic circuits are emerging working in the frequency range of 140-220 GHz (G-band) but they suffer from a lack of complete characterization tools involving costly investment. For example, there is currently no commercial vectorial network analyser (VNA) that can measure S parameters in the 4-ports G-band. The classical characterization of millimeter wave circuits in n ports (with n> 2) consists in using a vectorial analyzer of 2-ports networks and matching the other unused ports to 50Ω. By circular permutation, one thus manages to extract the S matrix from a device with n ports (with n> 2). This set up induces very long and difficult measurements and it requires on the one hand some very expensive measuring equipment at millimeter frequencies and on the other hand to implement accurate and dedicated calibration and de-embedding methods.Therefore, the work developed into this PhD study aimed to integrate in the die the measurement systems that would measure small signals "S-parameters" of the device under test (DUT). Being closer to the DST makes it possible to reduce the insertion losses, to reduce the amplitude of the error vectors and thus the residual errors after calibration. Moreover, it is possible to better control the power of the signal sent and to consider calibration methods using integrated loads, which reduces the time and cost processing. The technology used is the SiGe BiCMOS 55 nm technology developed by STMicroelectronics, a technology dedicated to RF and millimeter wave’s circuits.The system developed is a 1-port system. The solution developed consists on connecting the wafer with some probes and driving it with an external signal that spans the 35-55 GHz band. Once into the die, this signal is then quadrupled in frequency and amplified to reach good power level in G band at the DUT inputs. Some S-parameters (S11 and S22) are extracted from the DUT thanks to some very directive couplers designed respectively at the input and at the output of the DUT. The outputs of the couplers are then converted to low frequencies (IF =0.5-2.4 GHz) through passive frequency mixers.In a first part of the thesis manuscript, the way to work is argued, supported by a study of the state of the art concerning the measurement systems. Then, design and characterization of each blocks of the system are detailed: the frequency quadrupler in G band (composed of a W band frequency doubler, followed with a G band frequency doubler), the fully integrated transfer switch in G-band allowing driving the millimeter waves signal to the DUT input or to the DUT output, the directive couplers based on the slow wave lines, the frequency mixers used to bring back the results in base band frequency, etc… All the different blocks detailed, the measurement systems can be introduced. A first system, a one-port measurement system, has been designed as a proof of concept. Once the approach validated, a second system, two-ports measurement system, has been developed presenting an heterodyne architecture and a transfer switch in G band driving the input signal toward the DUT input or output
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FAVORETO, R. C. "Uma Proposta de Solução para Levantamento do Inventário dos Elementos de Rede em Redes Ópticas de Transporte". Universidade Federal do Espírito Santo, 2014. http://repositorio.ufes.br/handle/10/9648.
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Previous issue date: 2014-08-22As demandas por serviços de telecomunicações multimídia, garantia de QoS (Quality of Service) e mecanismos de gerenciamento e controle direcionam a evolução da rede de núcleo para adoção da tecnologia OTN (Optical Transport Network) como solução de rede de transporte. Para conduzir a evolução da tecnologia OTN a ITU-T (International Telecommunication Union Telecommunications Standardization Sector) estabelece uma série de recomendações, dentre elas, as específicas para o plano de gerenciamento de redes. Essas, por sua vez, apresentam deficiências no que se referem ao levantamento do inventário dos objetos gerenciados definidos pelas normas da ITU-T. A ITU-T define a representação dos elementos de rede em caráter funcional, mais especificamente como módulos de Funções Atômicas. Contudo, a falta de clareza na implementação das Funções Atômicas e a carência de integração com as representações físicas dos elementos de rede implica na omissão, por parte dos diversos fabricantes, da implementação dos mecanismos recomendados em norma. Esta dissertação tem como objetivo geral apresentar uma proposta de solução para o levantamento do inventário dos elementos de rede em redes OTN abrangendo de forma integrada as representações funcional e física do elemento de rede, além de possibilitar aos diversos fabricantes a aderência às normas da ITU-T bem como oferecer ao operador de rede a configuração dos componentes de uma forma mais intuitiva.
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Sutherland, Caleb Daniel. "Characterization and Molecular Targeting of a Mechanosensor Mechanism Controlled By the G-Quadruplex/I-Motif Molecular Switch in the MYC Promoter NHE III₁". Diss., The University of Arizona, 2015. http://hdl.handle.net/10150/566983.
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MYC is overexpressed in most types of tumors, but a means to selectively decrease its expression is yet to be found. Our recent findings on modulation of BCL2 gene expression through protein interactions with the BCL2 i-motif have provided a basis for further investigation of MYC gene control. It is proposed that the MYC i-motif could function by a similar molecular switch mechanism as in BCL2.Binding sites for heterogeneous nuclear ribonucleoprotein K (hnRNP K) within the MYC promoter also exist in the i-motif-forming sequence. Circular dichroism and bromine footprinting confirmed that this DNA sequence is able to form an i-motif, and systematic mutation of the cytosine residues in this sequence has revealed a 5:5:5 loop configuration. Indeed, all loops of the i-motif, when folded into a 5:5:5 loop configuration, contain the hnRNP K consensus sequence (CCCT). Previous studies show that hnRNP K binds to this i-motif-forming sequence, but it was assumed to be single-stranded. Binding studies revealed that hnRNP K has more binding affinity to its consensus sequence in the i-motif compared to a mutant sequence where the i-motif cannot form. Further investigation of the MYC promoter revealed an additional two runs of cytosine seven bases downstream of the MYC i-motif. Biophysical studies showed that the additional two runs were not involved in i-motif formation, however recent studies describe their importance for transcriptional activation. We found that hnRNP K preferred the longer 5CT sequence compared to the i-motif forming 4CT sequence when using a competitive binding assay. Utilizing luciferase reporters containing either the 4CT or 5CT sequence validated that hnRNP K required both the i-motif and 5th CT element for maximum transcriptional activation. Competition binding studies and bromine footprinting showed that hnRNP K bound to the downstream 5th CT element and the central and lateral loops of the i-motif.Additionally, we found that co-overexpression of Sp1 and hnRNP K induced a 10-fold increase in luciferase activity in the 5CT reporter only. We hypothesize that Sp1 continuously primes the promoter to initiate transcription inducing more negative superhelicity and increasing the melting of duplex DNA. This increased melting grants hnRNP K’s three KH domains access to the i-motif loops and the 5Th CT element. Confirmation by ChIP analysis validated that Sp1 overexpression causes an increase in hnRNP K occupancy at the MYC promoter. These findings provide new insight into the mechanisms of MYC transcriptional control by the i-motif and G-quadruplex.Recently, our group has demonstrated that two small molecules IMC-48 and IMC-76 can interact with the i-motif and can be an effective means to modulate BCL2 expression. Based on these results with the BCL2 i-motif, we employed a similar strategy and screened and identified small drug-like molecules that interact with MYC i-motif, using a FRET high-throughput assay. We then further validated that IMC-16 stabilizes the MYC i-motif through the interactions with the loops of the i-motif. No stabilization by IMC-16 treatment was observed with the MYC G-quadruplex and the BCL2 and PDGFRβi-motifs demonstrating selectivity for the MYC i-motif.Finally, we investigated the effects of IMC-16 on MYC expression in three lymphoma cell lines all expressing different levels of MYC. In the case of both Daudi and RAJI Burkitt’s lymphoma cell lines we demonstrated that selectively stabilizing the i-motif by IMC-16 could increase MYC expression. Furthermore, we demonstrated that the MYC G-quadruplex stabilizing compound GQC-05 and IMC-16, which stabilizes the MYC i-motif, have antagonistic effects on MYC expression, providing further evidence of a molecular switch mechanism in the NHEIII1. Directly targeting MYC expression through the i-motif offers advantages over targeting the G-quadruplex, because of the reduced stability and dynamic nature of the i-motif, additionally the i-motif is only found in DNA. The use of such i-motif interactive compounds is the first step into the development of new innovative approaches to treat cancers.
Książki na temat "G switch"
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H & G (Switched on Schoolhouse). Alpha Omega Publications (AZ), 2003.
Znajdź pełny tekst źródłaCzęści książek na temat "G switch"
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Zhang, Si-Cai, Kazem Nouri, Ehsan Amin, Mohamed S. Taha, Hossein Nakhaeizadeh, Saeideh Nakhaei-Rad, Radovan Dvorsky i Mohammad Reza Ahmadian. "Classical Rho Proteins: Biochemistry of Molecular Switch Function and Regulation". W Ras Superfamily Small G Proteins: Biology and Mechanisms 1, 327–40. Vienna: Springer Vienna, 2014. http://dx.doi.org/10.1007/978-3-7091-1806-1_14.
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Roach, Pat R., i Ben P. M. Helvensteijn. "A 3He-Gap Heat Switch for Use Below 2 K in Zero G". W Advances in Cryogenic Engineering, 923–30. Boston, MA: Springer US, 1992. http://dx.doi.org/10.1007/978-1-4615-3368-9_20.
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Cornelissen, Gunther, i Norbert Peyerimhoff. "Examples of Homologically Wide Actions". W Twisted Isospectrality, Homological Wideness, and Isometry, 73–83. Cham: Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-27704-7_9.
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AbstractAn action of a finite group G on a manifold M is homologically wide if the first homology of the manifold contains the regular representation of the group. In this chapter, we study this notion independently of the rest of this monograph. We first study the case where M is a surface and G acts freely, using the Lefschetz fixed point formula. We then recall a result of Broughton on the homology representation that allows us to deal with the case of a general action on a Riemann surface. After this, we switch to higher dimensional manifolds. We first recall Curtis’s theory of the virtual Lefschetz characters, and use results of Cooper and Long to construct examples and counterexamples to homological wideness in all dimensions ≥ 3. Finally, we study locally symmetric spaces. Property (T) implies that only the case of rank 1 is interesting, where we make some remarks on the relation to automorphic representations and Mostow rigidity. Finally, we study an example of using torsion homology: Mednykh’s explicit computation of the homology representation of the Seifert-Weber dodecahedral space, which we identify with a known modular representation through Brauer characters.
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Vidhyasekaran, P. "G-Proteins as Molecular Switches in Signal Transduction". W PAMP Signals in Plant Innate Immunity, 163–205. Dordrecht: Springer Netherlands, 2013. http://dx.doi.org/10.1007/978-94-007-7426-1_3.
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"THE WONDERFUL WORLD OF G PROTEINS AND G PROTEIN–COUPLED RECEPTORS". W The Molecular Switch, 170–200. Princeton University Press, 2020. http://dx.doi.org/10.2307/j.ctvx5w8pf.8.
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"5. THE WONDERFUL WORLD OF G PROTEINS AND G PROTEIN–COUPLED RECEPTORS". W The Molecular Switch, 170–200. Princeton University Press, 2020. http://dx.doi.org/10.1515/9780691200255-006.
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Sung, Ying-Ju, i Richard T. Ambron. "Protein kinase G is a molecular switch for pain". W The Neurobiology, Physiology, and Psychology of Pain, 67–77. Elsevier, 2022. http://dx.doi.org/10.1016/b978-0-12-820589-1.00007-5.
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Xie, Xiang-Qun, i Ananda Chowdhury. "Advances in Methods to Characterize Ligand-Induced Ionic Lock and Rotamer Toggle Molecular Switch in G Protein-Coupled Receptors". W G Protein Coupled Receptors - Structure, 153–74. Elsevier, 2013. http://dx.doi.org/10.1016/b978-0-12-391861-1.00007-1.
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Johnson, Christian W., i Carla Mattos. "The Allosteric Switch and Conformational States in Ras GTPase Affected by Small Molecules". W Inhibitors of the Ras Superfamily G-proteins, Part A, 41–67. Elsevier, 2013. http://dx.doi.org/10.1016/b978-0-12-416749-0.00003-8.
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Wu, Xiaohan, Ruijing Ge, Deji Akinwande i Jack C. Lee. "Memristors Based on 2D Monolayer Materials". W Memristor - An Emerging Device for Post-Moore’s Computing and Applications. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.98331.
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2D materials have been widely used in various applications due to their remarkable and distinct electronic, optical, mechanical and thermal properties. Memristive effect has been found in several 2D systems. This chapter focuses on the memristors based on 2D materials, e. g. monolayer transition metal dichalcogenides (TMDs) and hexagonal boron nitride (h-BN), as the active layer in vertical MIM (metal–insulator–metal) configuration. Resistive switching behavior under normal DC and pulse waveforms, and current-sweep and constant stress testing methods have been investigated. Unlike the filament model in conventional bulk oxide-based memristors, a new switching mechanism has been proposed with the assistance of metal ion diffusion, featuring conductive-point random access memory (CPRAM) characteristics. The use of 2D material devices in applications such as flexible non-volatile memory (NVM) and emerging zero-power radio frequency (RF) switch will be discussed.
Streszczenia konferencji na temat "G switch"
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Ramini, Abdallah, Mohammad I. Younis i Quang T. Su. "Low-G Electrostatically Actuated Resonant Switch". W ASME 2012 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/detc2012-70328.
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This work investigates a new concept of an electrostatically actuated resonant switch (EARS) for earthquake detection and low-g seismic applications. The resonator is proposed to operate close to instability bands of frequency-response curves, where it is forced to pull-in if operated within these bands. By careful tuning, the resonator can be made to enter the instability zone upon the detection of the earthquake signal, thereby pulling-in as a switch. Such a switching action can be functionalized for alarming purposes or can be used to activate a network of sensors for seismic activity recording. The EARS is modeled and its dynamic response is simulated using a nonlinear single degree of freedom model. Experimental investigation is conducted demonstrating the EARS capability of being triggered at small levels of acceleration as low as 0.02 g. Experimental data and simulation results are compared showing good agreement.
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Medina, Lior, Rivka Gilat i Slava Krylov. "Sub g Threshold Acceleration Sensor Incorporating Latched Bistable Beam". W ASME 2018 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/detc2018-85181.
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We present a concept and a theoretical feasibility study of a sub g threshold inertial micro sensor, which incorporates a curved bistable beam as a suspension element. For certain range of geometric parameters such a beam can exhibit lathing, namely remain in its switched configuration at zero actuating force. Since the device can be released from its latched state by an external acceleration force, it can therefore serve as a threshold inertial switch. While the snap-through force, associated with the switching from the initial to the buckled state, cannot be reduced without decreasing the frequency of the device, the release value of the acceleration can be tailored to be arbitrarily low. This allows design of a devices with sufficiently high stiffness in the initial and latched configurations, but with a very low release threshold. Our model show that for appropriately chosen parameters, it is possible to design a sub g threshold acceleration micro switch of realistic dimensions.
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Raghunathan, Nithin, Waterloo Tsutsui, Weinong Chen i Dimitrios Peroulis. "A single crystal silicon low-g switch tolerant to impact accelerations up to 24,000 g". W TRANSDUCERS 2015 - 2015 18th International Solid-State Sensors, Actuators and Microsystems Conference. IEEE, 2015. http://dx.doi.org/10.1109/transducers.2015.7181130.
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Ramanathan, Murugappan, i Rudra Pratap. "Energy Based Design And Validation of Latch MEMS g-Switch". W 2018 4th IEEE International Conference on Emerging Electronics (ICEE). IEEE, 2018. http://dx.doi.org/10.1109/icee44586.2018.8937948.
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Xiong, Z., B. Tang, F. Zhang, M. Yuan, J. Xie i C. Wang. "A Low-G MEMS Acceleration Switch Based on Direct Contact Method". W 2018 IEEE Sensors. IEEE, 2018. http://dx.doi.org/10.1109/icsens.2018.8630307.
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Xiong, Zhuang, Fengtian Zhang, Yingdong Pu, Bin Tang, Jie Yang i Chao Wang. "A silicon based low-g MEMS inertial switch for linear acceleration sensing application". W 2015 International Conference on Manipulation, Manufacturing and Measurement on the Nanoscale (3M-NANO). IEEE, 2015. http://dx.doi.org/10.1109/3m-nano.2015.7425457.
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Zhu, Ying-Min, Chun-Yue Huang, Jian-Yuan Jia i Kang-Qi Fan. "Simulation on Dynamic Characteristics of Micro Magnetic Acceleration Switch Based on Finite Element Method". W 2007 First International Conference on Integration and Commercialization of Micro and Nanosystems. ASMEDC, 2007. http://dx.doi.org/10.1115/mnc2007-21204.
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According to the characteristic that the force between a permanent magnetic couple changes nonlinearly with the magnetic displacement, a novel micro acceleration switch of permanent magnetic force is designed. The stiffness of the beam suspension, the module mass in the micro switch, and the magnetic force of the permanent magnet couple are selected as the major structure parameters and nine acceleration switches with every kind of combinations of the structure parameters were designed by using an orthogonal array. A Finite Element Method (FEM) model is built to simulate the contact force between the module and the contactors and the operation of the nine switches under a preset excitation wave of the environmental acceleration. The first 6 order natural frequencies and the vibration modals of the micro acceleration switch are obtained. The range analysis is given based on the simulation results of the contact forces. The results reveal that, in the three major structure parameters, the stiffness of the beam suspension W affects the electrical contact reliability the best with the permanent magnetic force F secondly and the mass G the least. The combination of structure factors that results in the best electrical reliability is W1G2F2, namely, the beam suspension stiffness W of 2134N/m, the module mass of 1.99g and the permanent magnetic force of 0.21N.
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Krakover, Naftaly, Ronen Maimon, Tamar Tepper-Faran, Noam Yitzhak i Slava Krylov. "Reliability of an 1000 G Range Vertically Integrated Silicon on Insulator (SOI) Impact Switch". W 2020 IEEE International Symposium on Inertial Sensors and Systems (INERTIAL). IEEE, 2020. http://dx.doi.org/10.1109/inertial48129.2020.9090023.
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Aouimeur, Walid, Marc Margalef-Rovira, Estelle Lauga-Larroze, Daniel Gloria, Christophe Gaquiere, Issa Alaji i Jean-Daniel Arnould. "A Fully-Integrated High-Isolation Transfer Switch for G-band in-situ Reflectometer applications". W 2020 IEEE MTT-S International Conference on Microwaves for Intelligent Mobility (ICMIM). IEEE, 2020. http://dx.doi.org/10.1109/icmim48759.2020.9299098.
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Lin, Luxing, Qiancheng Zhao, Zhenchuan Yang, Dacheng Zhang i Guizhen Yan. "Design and simulation of a 2-axis low g acceleration switch with multi-folded beams". W 2014 IEEE 12th International Conference on Solid -State and Integrated Circuit Technology (ICSICT). IEEE, 2014. http://dx.doi.org/10.1109/icsict.2014.7021682.
Pełny tekst źródłaRaporty organizacyjne na temat "G switch"
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Baker, Michael Sean, i Kenneth Roy Pohl. High-G testing of MEMS mechanical non-volatile memory and silicon re-entry switch. Office of Scientific and Technical Information (OSTI), październik 2005. http://dx.doi.org/10.2172/875630.
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Chen, Weinong W. Exploration of MEMS G-Switches at 100-10,000 G-Levels with Redundancy. Fort Belvoir, VA: Defense Technical Information Center, kwiecień 2014. http://dx.doi.org/10.21236/ada602474.
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Lahav, Ori, Albert Heber i David Broday. Elimination of emissions of ammonia and hydrogen sulfide from confined animal and feeding operations (CAFO) using an adsorption/liquid-redox process with biological regeneration. United States Department of Agriculture, marzec 2008. http://dx.doi.org/10.32747/2008.7695589.bard.
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The project was originally aimed at investigating and developing new efficient methods for cost effective removal of ammonia (NH₃) and hydrogen sulfide (H₂S) from Concentrated Animal Feeding Operations (CAFO), in particular broiler and laying houses (NH₃) and hog houses (H₂S). In both cases, the principal idea was to design and operate a dedicated air collection system that would be used for the treatment of the gases, and that would work independently from the general ventilation system. The advantages envisaged: (1) if collected at a point close to the source of generation, pollutants would arrive at the treatment system at higher concentrations; (2) the air in the vicinity of the animals would be cleaner, a fact that would promote animal growth rates; and (3) collection efficiency would be improved and adverse environmental impact reduced. For practical reasons, the project was divided in two: one effort concentrated on NH₃₍g₎ removal from chicken houses and another on H₂S₍g₎ removal from hog houses. NH₃₍g₎ removal: a novel approach was developed to reduce ammonia emissions from CAFOs in general, and poultry houses in particular. Air sucked by the dedicated air capturing system from close to the litter was shown to have NH₃₍g₎ concentrations an order of magnitude higher than at the vents of the ventilation system. The NH₃₍g₎ rich waste air was conveyed to an acidic (0<pH<~5) bubble column reactor where NH₃ was converted to NH₄⁺. The reactor operated in batch mode, starting at pH 0 and was switched to a new acidic absorption solution just before NH₃₍g₎ breakthrough occurred, at pH ~5. Experiments with a wide range of NH₃₍g₎ concentrations showed that the absorption efficiency was practically 100% throughout the process as long as the face velocity was below 4 cm/s. The potential advantages of the method include high absorption efficiency, lower NH₃₍g₎ concentrations in the vicinity of the birds, generation of a valuable product and the separation between the ventilation and ammonia treatment systems. A small scale pilot operation conducted for 5 weeks in a broiler house showed the approach to be technically feasible. H₂S₍g₎ removal: The main goal of this part was to develop a specific treatment process for minimizing H₂S₍g₎ emissions from hog houses. The proposed process consists of three units: In the 1ˢᵗ H₂S₍g₎ is absorbed into an acidic (pH<2) ferric iron solution and oxidized by Fe(III) to S⁰ in a bubble column reactor. In parallel, Fe(III) is reduced to Fe(II). In the 2ⁿᵈ unit Fe(II) is bio-oxidized back to Fe(III) by Acidithiobacillus ferrooxidans (AF).In the 3ʳᵈ unit S⁰ is separated from solution in a gravity settler. The work focused on three sub-processes: the kinetics of H₂S absorption into a ferric solution at low pH, the kinetics of Fe²⁺ oxidation by AF and the factors that affect ferric iron precipitation (a main obstacle for a continuous operation of the process) under the operational conditions. H₂S removal efficiency was found higher at a higher Fe(III) concentration and also higher for higher H₂S₍g₎ concentrations and lower flow rates of the treated air. The rate limiting step of the H₂S reactive absorption was found to be the chemical reaction rather than the transition from gas to liquid phase. H₂S₍g₎ removal efficiency of >95% was recorded with Fe(III) concentration of 9 g/L using typical AFO air compositions. The 2ⁿᵈ part of the work focused on kinetics of Fe(II) oxidation by AF. A new lab technique was developed for determining the kinetic equation and kinetic parameters (KS, Kₚ and mₘₐₓ) for the bacteria. The 3ʳᵈ part focused on iron oxide precipitation under the operational conditions. It was found that at lower pH (1.5) jarosite accumulation is slower and that the performance of the AF at this pH was sufficient for successive operation of the proposed process at the H₂S fluxes predicted from AFOs. A laboratory-scale test was carried out at Purdue University on the use of the integrated system for simultaneous hydrogen sulfide removal from a H₂S bubble column filled with ferric sulfate solution and biological regeneration of ferric ions in a packed column immobilized with enriched AFbacteria. Results demonstrated the technical feasibility of the integrated system for H₂S removal and simultaneous biological regeneration of Fe(III) for potential continuous treatment of H₂S released from CAFO. NH₃ and H₂S gradient measurements at egg layer and swine barns were conducted in winter and summer at Purdue. Results showed high potential to concentrate NH₃ and H₂S in hog buildings, and NH₃ in layer houses. H₂S emissions from layer houses were too low for a significant gradient. An NH₃ capturing system was designed and tested in a 100-chicken broiler room. Five bell-type collecting devices were installed over the litter to collect NH₃ emissions. While the air extraction system moved only 10% of the total room ventilation airflow rate, the fraction of total ammonia removed was 18%, because of the higher concentration air taken from near the litter. The system demonstrated the potential to reduce emissions from broiler facilities and to concentrate the NH₃ effluent for use in an emission control system. In summary, the project laid a solid foundation for the implementation of both processes, and also resulted in a significant scientific contribution related to AF kinetic studies and ferrous analytical measurements.
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Grumet, Rebecca, Rafael Perl-Treves i Jack Staub. Ethylene Mediated Regulation of Cucumis Reproduction - from Sex Expression to Fruit Set. United States Department of Agriculture, luty 2010. http://dx.doi.org/10.32747/2010.7696533.bard.
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Reproductive development is a critical determinant of agricultural yield. For species with unisexual flowers, floral secualdifferentation adds additional complexity, that can influenec productivity. The hormone ethylene has long, been known to play a primary role in sex determination in the Cucumis species cucumber (C. sativus) and melon (C. melo). Our objectives were to: (1) Determine critical sites of ethylene production and perception for sex determination; (2) Identify additional ethylene related genes associated with sex expression; and (3) Examine the role of environment ami prior fruit set on sex expression, pistillate flower maturation, and fruit set. We made progress in each of these areas. (1) Transgenic melon produced with the Arabidopsis dominant negative ethylene perception mutant gene, etrl-1, under the control of floral primordia targeted promoters [AP3 (petal and stamen) and CRC (carpel and nectary)], showed that ethylene perception by the stamen primordia, rather than carpel primordia, is critical for carpel development at the time of sex determination. Transgenic melons also were produced with the ethylene production enzyme gene. ACS, encoding l-aminocyclopropane-lcarboylate synthase, fused to the AP3 or CRC promoters. Consistent with the etr1-1 results, CRC::ACS did not increase femaleness; however, AP3::ACS reduced or eliminated male flower production. The effects of AP3:ACS were stronger than those of 35S::ACS plants, demonstratin g the importance of targeted expression, while avoiding disadvantages of constitutive ethylene production. (2) Linkage analysis coupled with SNP discovery was per formed on ethylene and floral development genes in cucumber populations segregating for the three major sex genes. A break-through towards cloning the cucumber M gene occurred when the melon andromonoecious gene (a), an ACS gene, was cloned in 2008. Both cucumber M and melon a suppress stamen development in pistillate flowers. We hypothesized that cucumber M could be orthologous to melon a, and found that mutations in CsACS2 co-segregated perfectly with the M gene. We also sought to identify miRNA molecules associated with sex determination. miRNA159, whose target in Arabidopsis is GAMYB[a transcription factor gene mediating response to10 gibberellin (GA)], was more highly expressed in young female buds than male. Since GA promotes maleness in cucumber, a micro RNA that counteracts GAMYB could promote femaleness. miRNA157, which in other plants targets transcription factors involved in flower development , was expressed in young male buds and mature flower anthers. (3) Gene expression profiling showed that ethylene-, senescence-, stress- and ubiquitin-related genes were up-regulated in senescing and inhibited fruits, while those undergoing successful fruit set up-regulated photosynthesis, respiration and metabolic genes. Melon plants can change sex expression in response to environmental conditions, leading to changes in yield potential. Unique melon lines with varying sex expression were developed and evaluated in the field in Hancock, Wisconsin . Environmental changes during the growing season influenced sex expression in highly inbred melon lines. Collectively these results are of significance for understanding regulation of sex expression. The fact that both cucumber sex loci identified so far (F and M) encode isoforms of the same ethylene synthesis enzyme, underscores the importance of ethylene as the main sex determining hormone in cucumber. The targeting studies give insight into developmental switch points and suggest a means to develop lines with earlier carpel-bearing flower production and fruit set. These results are of significance for understanding regulation of sex expression to facilitate shorter growing seasons and earlier time to market. Field results provide information for development of management strategies for commercial production of melon cultivars with different sex expression characteristics during fruit production.
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Dickman, Martin B., i Oded Yarden. Genetic and chemical intervention in ROS signaling pathways affecting development and pathogenicity of Sclerotinia sclerotiorum. United States Department of Agriculture, lipiec 2015. http://dx.doi.org/10.32747/2015.7699866.bard.
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Abstract: The long-term goals of our research are to understand the regulation of sclerotial development and pathogenicity in S. sclerotior11111. The focus in this project was on the elucidation of the signaling events and environmental cues involved in the regulation of these processes, utilizing and continuously developing tools our research groups have established and/or adapted for analysis of S. sclerotiorum, Our stated objectives: To take advantage of the recent conceptual (ROS/PPs signaling) and technical (amenability of S. sclerotiorumto manipulations coupled with chemical genomics and next generation sequencing) developments to address and extend our fundamental and potentially applicable knowledge of the following questions concerning the involvement of REDOX signaling and protein dephosphorylation in the regulation of hyphal/sclerotial development and pathogenicity of S. sclerotiorum: (i) How do defects in genes involved in ROS signaling affect S. sclerotiorumdevelopment and pathogenicity? (ii) In what manner do phosphotyrosinephosphatases affect S. sclerotiorumdevelopment and pathogenicity and how are they linked with ROS and other signaling pathways? And (iii) What is the nature of activity of newly identified compounds that affect S. sclerotiori,111 growth? What are the fungal targets and do they interfere with ROS signaling? We have met a significant portion of the specific goals set in our research project. Much of our work has been published. Briefly. we can summarize that: (a) Silencing of SsNox1(NADPHoxidase) expression indicated a central role for this enzyme in both virulence and pathogenic development, while inactivation of the SsNox2 gene resulted in limited sclerotial development, but the organism remained fully pathogenic. (b) A catalase gene (Scatl), whose expression was highly induced during host infection is involved in hyphal growth, branching, sclerotia formation and infection. (c) Protein tyrosine phosphatase l (ptpl) is required for sclerotial development and is involved in fungal infection. (d) Deletion of a superoxidedismutase gene (Sssodl) significantly reduced in virulence on both tomato and tobacco plants yet pathogenicity was mostly restored following supplementation with oxalate. (e) We have participated in comparative genome sequence analysis of S. sclerotiorumand B. cinerea. (f) S. sclerotiorumexhibits a potential switch between biotrophic and necrotrophic lifestyles (g) During plant microbe interactions cell death can occur in both resistant and susceptible events. Non pathogenic fungal mutants S. sclerotior111n also cause a cell death but with opposing results. We investigated PCD in more detail and showed that, although PCD occurs in both circumstances they exhibit distinctly different features. The mutants trigger a restricted cell death phenotype in the host that unexpectedly exhibits markers associated with the plant hypersensitive (resistant) response. Using electron and fluorescence microscopy, chemical effectors and reverse genetics, we have established that this restricted cell death is autophagic. Inhibition of autophagy rescued the non-pathogenic mutant phenotype. These findings indicate that autophagy is a defense response in this interaction Thus the control of cell death, dictated by the plant (autophagy) סr the fungus (apoptosis), is decisive to the outcome of certain plant microbe interactions. In addition to the time and efforts invested towards reaching the specific goals mentioned, both Pls have initiated utilizing (as stated as an objective in our proposal) state of the art RNA-seq tools in order to harness this technology for the study of S. sclerotiorum. The Pls have met twice (in Israel and in the US), in order to discuss .נחd coordinate the research efforts. This included a working visit at the US Pls laboratory for performing RNA-seq experiments and data analysis as well as working on a joint publication (now published). The work we have performed expands our understanding of the fundamental biology (developmental and pathogenic) of S. sclerotioז111וז. Furthermore, based on our results we have now reached the conclusion that this fungus is not a bona fide necrotroph, but can also display a biotrophic lifestyle at the early phases of infection. The data obtained can eventually serve .נ basis of rational intervention with the disease cycle of this pathogen.