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Articles de revues sur le sujet "2D RFA model"
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Ni, Tie-Hua, William F. McDonald, Irene Zolotukhin, Thomas Melendy, Shou Waga, Bruce Stillman et Nicholas Muzyczka. « Cellular Proteins Required for Adeno-Associated Virus DNA Replication in the Absence of Adenovirus Coinfection ». Journal of Virology 72, no 4 (1 avril 1998) : 2777–87. http://dx.doi.org/10.1128/jvi.72.4.2777-2787.1998.
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ABSTRACT We previously reported the development of an in vitro adeno-associated virus (AAV) DNA replication system. The system required one of the p5 Rep proteins encoded by AAV (either Rep78 or Rep68) and a crude adenovirus (Ad)-infected HeLa cell cytoplasmic extract to catalyze origin of replication-dependent AAV DNA replication. However, in addition to fully permissive DNA replication, which occurs in the presence of Ad, AAV is also capable of partially permissive DNA replication in the absence of the helper virus in cells that have been treated with genotoxic agents. Limited DNA replication also occurs in the absence of Ad during the process of establishing a latent infection. In an attempt to isolate uninfected extracts that would support AAV DNA replication, we discovered that HeLa cell extracts grown to high density can occasionally display as much in vitro replication activity as Ad-infected extracts. This finding confirmed previous genetic analyses which suggested that no Ad-encoded proteins were absolutely essential for AAV DNA replication and that the uninfected extracts should be useful for studying the differences between helper-dependent and helper-independent AAV DNA replication. Using specific chemical inhibitors and monoclonal antibodies, as well as the fractionation of uninfected HeLa extracts, we identified several of the cellular enzymes involved in AAV DNA replication. They were the single-stranded DNA binding protein, replication protein A (RFA), the 3′ primer binding complex, replication factor C (RFC), and proliferating cell nuclear antigen (PCNA). Consistent with the current model for AAV DNA replication, which requires only leading-strand DNA synthesis, we found no requirement for DNA polymerase α-primase. AAV DNA replication could be reconstituted with purified Rep78, RPA, RFC, and PCNA and a phosphocellulose chromatography fraction (IIA) that contained DNA polymerase activity. As both RFC and PCNA are known to be accessory proteins for polymerase δ and ɛ, we attempted to reconstitute AAV DNA replication by substituting either purified polymerase δ or polymerase ɛ for fraction IIA. These attempts were unsuccessful and suggested that some novel cellular protein or modification was required for AAV DNA replication that had not been previously identified. Finally, we also further characterized the in vitro DNA replication assay and demonstrated by two-dimensional (2D) gel electrophoresis that all of the intermediates commonly seen in vivo are generated in the in vitro system. The only difference was an accumulation of single-stranded DNA in vivo that was not seen in vitro. The 2D data also suggested that although both Rep78 and Rep68 can generate dimeric intermediates in vitro, Rep68 is more efficient in processing dimers to monomer duplex DNA. Regardless of the Rep that was used in vitro, we found evidence of an interaction between the elongation complex and the terminal repeats. Nicking at the terminal repeats of a replicating molecule appeared to be inhibited until after elongation was complete.
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PARK, SEUNG MAN, YOUNG UK MIN, MYUNG JIN KANG, KYUNG CHUN KIM et HO SEONG JI. « IN VITROHEMODYNAMIC STUDY ON THE STENOTIC RIGHT CORONARY ARTERY USING EXPERIMENTAL AND NUMERICAL ANALYSIS ». Journal of Mechanics in Medicine and Biology 10, no 04 (décembre 2010) : 695–712. http://dx.doi.org/10.1142/s0219519410003812.
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To investigate the hemodynamic and hemorheological features related to circulatory diseases, in vitro experiments are carried out using a micro-particle image velocimetry (μ-PIV) technique. Numerical simulations using a commercial computational fluid dynamics (CFD) code are also performed to compare with the experimental results. Five different non-Newtonian blood models and a Newtonian water model are employed to investigate the blood flow characteristics through a stenotic right coronary artery (RCA). The in vitro model is made of two-dimensional (2D) polydimethylsiloxane (PDMS) channel based on the clinical angiogram of the RCA with stenotic lesion. The hemodynamic and hemorheologic behaviors in the control volume near the stenotic lesion are evaluated by velocity profiles. The predicted and measured velocity profiles at the center of the channel have a reasonable agreement.
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Ayache, Assia, Soumia Kharfouchi et Fouad Rahmani. « Combination of a 2D-RCA model and ANNs for texture image segmentation ». International Journal of Computing Science and Mathematics 15, no 3 (2022) : 289. http://dx.doi.org/10.1504/ijcsm.2022.124691.
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Ayache, Assia, Fouad Rahmani et Soumia Kharfouchi. « Combination of a 2D-RCA model and ANNs for texture image segmentation ». International Journal of Computing Science and Mathematics 15, no 3 (2022) : 289. http://dx.doi.org/10.1504/ijcsm.2022.10049408.
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Guan, Zhongzheng, Peng Wang, Yue Li, Yong Li, Bo Hu et Yichao Wang. « Mesoscale Finite Element Modeling of Mortar under Sulfate Attack ». Materials 15, no 15 (8 août 2022) : 5452. http://dx.doi.org/10.3390/ma15155452.
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In this paper, a 2D mesoscale finite element (FE) numerical model of mortar, considering the influence of the ITZ, was proposed to evaluate the corrosion of mortar in sodium sulfate. On the mesoscale, the corroded mortar was regarded as a three-phase composite material composed of sand, cement paste, and an interface transition zone (ITZ). Firstly, the volume fractions and mechanical parameters (elastic modulus, Poisson’s ratio, and strength) of the mesoscale phases were obtained. Then, the cement paste and the ITZ were combined to form an equivalent matrix by homogenization methods, and the calibrated constitutive relations of the equivalent matrix were established. Subsequently, a two-dimensional (2D) random circular aggregate (RCA) model and a 2D random polygonal aggregate (RPA) model of corroded mortar were established using the random aggregate model. The failure process of corroded mortar specimens under uniaxial compression was simulated by the mesoscale FE numerical model. Comparing the simulation results with the measured stress–strain curves of the uniaxial compression test, it was found that the simulation results of the 2D RP model were closer to the experimental results than those of the 2D RC model. Meanwhile, the numerical simulation results were in good agreement with the experimental results, and the error values of peak stress between the simulation results and the measured results were within 7%, which showed that the 2D mesoscale FE model could accurately predict the results of a uniaxial compression test of a mortar specimen under sulfate attack.
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Boulemnadjel, Amel, Fella Hachouf et Soumia Kharfouchi. « GMM Estimation of 2D-RCA Models With Applications to Texture Image Classification ». IEEE Transactions on Image Processing 25, no 2 (février 2016) : 528–39. http://dx.doi.org/10.1109/tip.2015.2494740.
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Cheng, Zhe, Fei Chen, Xile Liu, Cong Gao, Linchao Jia et Yuanzhi Lao. « Abstract 5460 : Preclinical characterization of QLH11906, a novel pan-RAF inhibitor ». Cancer Research 82, no 12_Supplement (15 juin 2022) : 5460. http://dx.doi.org/10.1158/1538-7445.am2022-5460.
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Abstract Background: The type 1/2 BRAF inhibitors (e.g., vemurafenib) have been used for patients with BRAFV600E-mutant tumors. But the application of the inhibitors was restricted to a few types of tumors (e.g., melanoma). Common adverse effects such as pruritus and skin papilloma have limited the usage. It could be attributed to the paradoxical activation of the MAPK pathway. The paradoxical activation also leads to tumor promotion in BRAF wild-type melanoma and skin toxicity in 30%-70% patients with KRAS mutations. Therefore, development of type II pan-RAF inhibitors which avoid MAPK paradoxical activation is necessary. Methods: The selective pan-RAF inhibitor QLH11906 was tested on A/B/C RAF kinases and a representative kinase panel. Both 2D and 3D proliferation studies were conducted for cell lines with BRAF and various KRAS mutations, followed by both immunoprecipitation and ERK phosphorylation assays to elucidate the mode of action. Combination studies with MEK inhibitors were implemented in both KRAS-mutant cell lines and BRAF/KRAS-mutant patient derived organoids (PDO). Single-agent and combination studies were also carried out in vivo on both BRAF/KRAS-mutant cell line-derived xenograft (CDX) and KRAS-mutant patient-derived xenograft (PDX) models. Results: QLH11906 inhibited wild-type A/B/C RAF and BRAFV600E with the IC50 of 4.9, 1.9, 0.5, and 1.1 nM, respectively, and showed no inhibition at 1 μM in a selectivity panel of 28 kinases except for DDR1 and DDR2. Under 2D culture condition, QLH11906 inhibited proliferation of various BRAF/KRAS-mutant cell lines (IC50 300-1700 nM) and suppressed ERK phosphorylation (IC50 20-600 nM). In 3D cultures, QLH11906 showed higher activity in proliferation suppression in both HCT116 (KRASG13D, IC50 24 nM 3D vs 1186 nM 2D) and Calu-6 (KRASQ61K, IC50 85 nM 3D vs 1411 nM 2D). In immunoprecipitation studies with HCT116 and Calu-6 cells, both BRAF homodimers and BRAF/CRAF heterodimers could be detected under the treatment of QLH11906. QLH11906 showed synergistic effect when combined with MEK inhibitors trametinib or cobimetinib in KRAS-mutant cell lines, including A549 (KRASG12S), Calu-6, HCT116, NCIH2122 (KRASG12C) and Panc1005 (KRASG12D), and 77%-99% tumor suppression was reached at the expected clinical Ctrough concentrations. Synergistic effects with trametinib were observed in PDO models including pancreatic cancers (KRASG12D and KRASG12V), colon cancers (KRASG12D and KRASG13D) and lung cancers (KRASG12V). QLH11906 also promoted tumor shrinkage in vivo as a single agent in Calu-6, HCT116, and Colo-205 (BRAFV600E) CDX models or combined with trametinib in PDX models (KRASG12C lung cancers and KRASG12C colon cancers) Conclusion: QLH11906 is a highly selective pan-RAF inhibitor with promising antitumor activity both in vitro and in vivo. It is hopeful to be a therapeutic agent for BRAF and KRAS-mutant tumor patients. Citation Format: Zhe Cheng, Fei Chen, Xile Liu, Cong Gao, Linchao Jia, Yuanzhi Lao. Preclinical characterization of QLH11906, a novel pan-RAF inhibitor [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5460.
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Hall, Brett, Praveen Nair, Kevin Fowler, Amy Axel, Sarah Kolitz, Jason Funt, Scott Barrett, Benjamin Zeskind et Peter J. King. « Translational modeling for patients with RAS mutant tumors : Profiling the dual-MEK inhibitor IMM-1-104 in a humanized 3D assay. » Journal of Clinical Oncology 40, no 16_suppl (1 juin 2022) : e15084-e15084. http://dx.doi.org/10.1200/jco.2022.40.16_suppl.e15084.
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e15084 Background: Elevated RAS-RAF-MEK-ERK (MAPK pathway) signaling is observed in over half of all solid human tumors, and mutations in RAS or RAF account for a large fraction. Given MEK’s unique position in the MAPK cascade, it remains an attractive target in cancer. However, FDA-registered MEK inhibitors are susceptible to pathway reactivation events that limit their use to RAF mutant disease and cause on-target toxicities stemming from chronic target engagement. IMM-1-104 is a novel, allosteric dual-MEK inhibitor designed for better applicability to RAS mutant tumors by preventing MEK reactivation. Endowed with a short plasma half-life, IMM-1-104 promotes deep cyclic inhibition with a near-zero drug trough, affording normal cells a chance to recover between doses. Methods: We characterized IMM-1-104’s pharmacologic activity across 52 tumor cell lines that spanned 11 distinct tumor types in a humanized, ECM-based 3D tumor growth assay (3D-TGA). The 3D-TGA has better predicted in vivo tumor responses versus 2D culture and more accurately reflects human tumor biology. Tumor models were categorized based on in vivo drug PK limits as sensitive to IMM-1-104 (EC50 < 1uM), intermediate (1uM≤EC50≤10uM and ≥25% inhibition at 10uM) or resistant otherwise. Models were evaluated by whole exome sequencing, along with RNA sequencing in the 3D context, to profile determinants of sensitivity and resistance and to prioritize patient populations most likely to respond to IMM-1-104. Results: Models sensitive to IMM-1-104 were enriched for MAPK driver mutations, consistent with pathway addiction. We reasoned that activation of parallel compensatory pathways that can reduce reliance on MAPK signaling may increase the likelihood of resistance to IMM-1-104. Pathways and genes suspected of contributing to resistance helped refine signatures based on 3D-TGA outcome data. Models with a MAPK driver mutation and compensatory mutations such as PIK3CA or PTEN deletion were more likely to show intermediate response than those with a greater addiction to MAPK drivers. Models lacking a clear MAPK driver mutation but harboring other putative resistance alterations were more likely to be resistant in the 3D-TGA. Conclusions: To better understand the relevance of tumor model responses in the 3D-TGA relative to RAS mutant patient populations, we computationally compared tumor model data to patient somatic alterations, identified in the public resource GENIE, which has cataloged the molecular profiles of over 100,000 cancer patients. Based on model-to-patient molecular mapping, we identified biomarker-defined subsets of sensitive KRAS mutant lung and colorectal models. The most broadly sensitive patient-aligned models in the 3D assay were KRAS mutant pancreatic cancer and NRAS mutant melanoma patients, supporting the inclusion of such patients in planned clinical studies of IMM-1-104.
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Hall, Brett, Praveen Nair, Kevin Fowler, Amy Axel, Sarah Kolitz, Jason Funt, Scott Barrett, Benjamin Zeskind et Peter J. King. « Translational modeling for patients with RAS mutant tumors : Profiling the dual-MEK inhibitor IMM-1-104 in a humanized 3D assay. » Journal of Clinical Oncology 40, no 16_suppl (1 juin 2022) : e15084-e15084. http://dx.doi.org/10.1200/jco.2022.40.16_suppl.e15084.
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e15084 Background: Elevated RAS-RAF-MEK-ERK (MAPK pathway) signaling is observed in over half of all solid human tumors, and mutations in RAS or RAF account for a large fraction. Given MEK’s unique position in the MAPK cascade, it remains an attractive target in cancer. However, FDA-registered MEK inhibitors are susceptible to pathway reactivation events that limit their use to RAF mutant disease and cause on-target toxicities stemming from chronic target engagement. IMM-1-104 is a novel, allosteric dual-MEK inhibitor designed for better applicability to RAS mutant tumors by preventing MEK reactivation. Endowed with a short plasma half-life, IMM-1-104 promotes deep cyclic inhibition with a near-zero drug trough, affording normal cells a chance to recover between doses. Methods: We characterized IMM-1-104’s pharmacologic activity across 52 tumor cell lines that spanned 11 distinct tumor types in a humanized, ECM-based 3D tumor growth assay (3D-TGA). The 3D-TGA has better predicted in vivo tumor responses versus 2D culture and more accurately reflects human tumor biology. Tumor models were categorized based on in vivo drug PK limits as sensitive to IMM-1-104 (EC50 < 1uM), intermediate (1uM≤EC50≤10uM and ≥25% inhibition at 10uM) or resistant otherwise. Models were evaluated by whole exome sequencing, along with RNA sequencing in the 3D context, to profile determinants of sensitivity and resistance and to prioritize patient populations most likely to respond to IMM-1-104. Results: Models sensitive to IMM-1-104 were enriched for MAPK driver mutations, consistent with pathway addiction. We reasoned that activation of parallel compensatory pathways that can reduce reliance on MAPK signaling may increase the likelihood of resistance to IMM-1-104. Pathways and genes suspected of contributing to resistance helped refine signatures based on 3D-TGA outcome data. Models with a MAPK driver mutation and compensatory mutations such as PIK3CA or PTEN deletion were more likely to show intermediate response than those with a greater addiction to MAPK drivers. Models lacking a clear MAPK driver mutation but harboring other putative resistance alterations were more likely to be resistant in the 3D-TGA. Conclusions: To better understand the relevance of tumor model responses in the 3D-TGA relative to RAS mutant patient populations, we computationally compared tumor model data to patient somatic alterations, identified in the public resource GENIE, which has cataloged the molecular profiles of over 100,000 cancer patients. Based on model-to-patient molecular mapping, we identified biomarker-defined subsets of sensitive KRAS mutant lung and colorectal models. The most broadly sensitive patient-aligned models in the 3D assay were KRAS mutant pancreatic cancer and NRAS mutant melanoma patients, supporting the inclusion of such patients in planned clinical studies of IMM-1-104.
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Miller, Nichol L. G., Tim S. Wang, Paul Severson, Ping Jiang, Michelle Perez, Noel Timple, Toufike Kanouni, Aleksandra Franovic, Eric S. Martin et Eric Murphy. « Abstract 2674 : Antitumor activity of KIN-2787, a next-generation pan-RAF inhibitor, in preclinical models of human RAF/RAS mutant melanoma ». Cancer Research 82, no 12_Supplement (15 juin 2022) : 2674. http://dx.doi.org/10.1158/1538-7445.am2022-2674.
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Abstract Background: In the US in 2021, invasive melanoma will account for an estimated 106,000 new cases and > 7,000 deaths. Somatic mutations that activate the MAPK signaling pathway are a leading cause of melanoma with 50% harboring oncogenic BRAF alterations and another 20% with activating NRAS mutations. Of note, NRAS mutant melanoma has been shown to be dependent upon RAF signaling via CRAF dimers for downstream activation of MEK/ERK. While targeted therapies are approved for V600 (Class I, monomer-driven) BRAF mutant melanoma, no approved targeted therapy exists for patients with melanoma driven by Class II or Class III dimer-dependent BRAF alterations or NRAS mutations. KIN-2787 is a novel, orally available, potent, and selective pan-RAF inhibitor designed to be effective in RAF-dependent cancers, including all classes of BRAF alterations, by targeting mutant BRAF monomers and RAF dimers, regardless of isoform. Methods: KIN-2787 activity was assessed by suppression of downstream MAPK pathway signaling and subsequent cell growth inhibition in a panel of human melanoma cell lines. In vivo KIN-2787 efficacy was evaluated in BRAF and NRAS mutant melanoma cell- and patient-derived xenograft models. Results: KIN-2787 cellular activity was measured by inhibition of ERK phosphorylation across a panel of melanoma cell lines, including those harboring Class I BRAF alterations, Class II and III BRAF alterations, NRAS mutations, KRAS mutations, and wild type RAF/RAS. In contrast to vemurafenib, an approved BRAF inhibitor with activity limited to Class I BRAF alterations, KIN-2787 was active across all classes of BRAF mutant melanoma cells (EC50 values < 100 nM). NRAS and KRAS mutant cell lines were moderately responsive to KIN-2787 inhibition. Melanoma cells expressing wild type RAS/RAF were the least sensitive to MAPK pathway inhibition by KIN-2787. KIN-2787 also inhibited cell proliferation in BRAF and NRAS mutant melanoma in 2D and 3D cell cultures. Daily KIN-2787 treatment resulted in significant tumor growth inhibition in human melanoma xenograft models bearing Class I, II and III BRAF alterations as well as NRAS mutations and was associated with MAPK pathway suppression. Additionally, KIN-2787 was efficacious in a pre-/post-treatment melanoma PDX pair in which the original tumor was Class I BRAF V600E but acquired a Class II BRAF kinase domain duplication upon progression on dabrafenib + trametinib. Details from the above findings will be presented at the meeting. Conclusions: KIN-2787 is a next-generation, pan-RAF inhibitor with in vitro and in vivo activity against human melanoma driven by BRAF and/or NRAS mutations. Data supports KIN-2787 use in acquired BRAF dimer-dependent resistance to BRAF+MEK inhibitor therapy. A Phase I dose escalation and expansion clinical trial evaluating the safety and efficacy of KIN-2787 is ongoing (NCT04913285). Citation Format: Nichol L. G. Miller, Tim S. Wang, Paul Severson, Ping Jiang, Michelle Perez, Noel Timple, Toufike Kanouni, Aleksandra Franovic, Eric S. Martin, Eric Murphy. Antitumor activity of KIN-2787, a next-generation pan-RAF inhibitor, in preclinical models of human RAF/RAS mutant melanoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2674.
Thèses sur le sujet "2D RFA model"
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Barni, N. « Nonlinear buffeting response of suspension bridges considering time-variant self-excited forces ». Doctoral thesis, 2022. http://hdl.handle.net/2158/1278784.
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In the last thirty years, the aerodynamic nonlinearities related to the slow variation of the angle of attack produced by large-scale atmospheric turbulence and their impact on the buffeting response of long-span suspension bridges have been a hot topic in wind engineering research. Self-excited forces accounting for such an effect of turbulence have been crucial in predicting the dynamic response of bridge sectional models and long-span suspension bridges subjected to multi-harmonic gusts and the turbulent wind, respectively. Despite several nonlinear aerodynamic models produced by the scientific community throughout the last years, only few studies on full suspension bridges nonlinear buffeting response in realistic turbulent flows are available. This doctoral work addresses this topic, aiming to enlarge the understanding of the effects of turbulence on the suspension bridge buffeting response.
The first contribution of this work concerns nonlinear aerodynamic load modelling. Indeed, large-scale atmospheric turbulence produces large-amplitude low-frequency fluctuations of the angle of attack that can significantly change the self-excited and the external buffeting forces acting on a bridge deck. Assuming that the angle of attack varies slowly compared to the bridge motion, a time-variant linear model relying on Roger’s rational function approximation (RFA) of the force transfer function is proposed for modelling self-excited forces. In particular, an existing model is improved by a flexible fitting of the RFA directly in the multivariate space of reduced velocity and angle of attack. Another contribution of the present work is setting up an experimental procedure based on bi- or multi-harmonic forced-vibration tests to underscore the variation of magnitude and phase of self-excited forces under a time-variant angle of attack. These wind tunnel tests also allowed a sound experimental validation of the proposed model, considering two quite different bridge deck cross-sections as case studies. Aerodynamic derivatives for various angles of attack were measured to determine the model parameters. Despite its simplicity, the model yields accurate results up to relatively fast variations of the angle of attack, and it can reproduce the complicated behaviour of the self-excited forces revealed by the experiments. The model performance strongly depends on the goodness of the RFA-based fitting of aerodynamic derivatives, and the excellent results obtained were possible thanks to the high flexibility of the proposed method. Then, the nonlinear external buffeting forces are formulated to achieve a reasonable compromise between the conflicting needs of modelling both nonlinear and unsteady effects of wind velocity fluctuations.
Then, the proposed 2D RFA model for self-excited forces and the nonlinear buffeting forces are incorporated into a stochastic time-variant state-space framework to assess the nonlinear buffeting response of a suspension bridge. The most important feature of this model is the modulation of the self-excited forces due to the spatio-temporal fluctuation of the angle of attack produced by low-frequency turbulence. Such an angle of attack accounts for the spatial wind correlation along the bridge girder. The model is applied to the Hardanger Bridge in Norway, considering different wind conditions. Indeed, the aerodynamic derivatives of this bridge deck cross-section present a strong dependence on the mean angle of attack. Moreover, a novel approach is suggested, diversifying the cut-off frequencies for the considered input motion components in the self-excited forces. In the wake of this, the thesis also investigates the sensitivity of the response statistics to the model cut-offs used to separate the low-frequency and the high-frequency turbulence band. The results emphasise the significant impact on the buffeting response and flutter stability of considering time-variant self-excited forces, though in specific cases the classical linear time-invariant approach is found to provide accurate predictions of the bridge vibrations.
Livres sur le sujet "2D RFA model"
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Horing, Norman J. Morgenstern. Random Phase Approximation Plasma Phenomenology, Semiclassical and Hydrodynamic Models ; Electrodynamics. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198791942.003.0010.
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Chapter 10 reviews both homogeneous and inhomogeneous quantum plasma dielectric response phenomenology starting with the RPA polarizability ring diagram in terms of thermal Green’s functions, also energy eigenfunctions. The homogeneous dynamic, non-local inverse dielectric screening functions (K) are exhibited for 3D, 2D, and 1D, encompassing the non-local plasmon spectra and static shielding (e.g. Friedel oscillations and Debye-Thomas-Fermi shielding). The role of a quantizing magnetic field in K is reviewed. Analytically simpler models are described: the semiclassical and classical limits and the hydrodynamic model, including surface plasmons. Exchange and correlation energies are discussed. The van der Waals interaction of two neutral polarizable systems (e.g. physisorption) is described by their individual two-particle Green’s functions: It devolves upon the role of the dynamic, non-local plasma image potential due to screening. The inverse dielectric screening function K also plays a central role in energy loss spectroscopy. Chapter 10 introduces electromagnetic dyadic Green’s functions and the inverse dielectric tensor; also the RPA dynamic, non-local conductivity tensor with application to a planar quantum well. Kramers–Krönig relations are discussed. Determination of electromagnetic response of a compound nanostructure system having several nanostructured parts is discussed, with applications to a quantum well in bulk plasma and also to a superlattice, resulting in coupled plasmon spectra and polaritons.
Chapitres de livres sur le sujet "2D RFA model"
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DOS SANTOS XAVIER DIAS, ISABELLE, DAPHNE PINHEIRO DA SILVA, KARINA RIBEIRO DA SILVA PEREIRA, ANA CAROLINA STUMBO MACHADO, ALESSANDRA ALVES THOLE, ERIKA AFONSO COSTA CORTEZ MARQUES, LAÍS DE CARVALHO et SIMONE NUNES DE CARVALHO. « COMPARAÇÃO DOS EFEITOS TERAPÊUTICOS ENTRE SECRETOMAS DE CULTURA 2D E 3D DE CÉLULAS-TRONCO DO TECIDO ADIPOSO (CTA) EM MODELO EXPERIMENTAL DE DIABETES TIPO 1 ». Dans Proceedings of the 2nd International Digital Congress on 3D Biofabrication and Bioprinting (3DBB) - Biofabrication, Bioprinting, Additive Manufacturing applied to health. Editora Realize, 2022. http://dx.doi.org/10.46943/ii.3dbb.2022.01.006.
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DIABETES TIPO 1 (DT1) ? UMA DOEN?A EM QUE AS C?LULAS BETA DO P?NCREAS S?O DESTRU?DAS, LEVANDO A QUEDA NA PRODU??O DE INSULINA E HIPERGLICEMIA. TERAPIAS COM C?LULAS-TRONCO S?O UTILIZADAS EM V?RIOS ESTUDOS EXPERIMENTAIS E CL?NICOS EM DOEN?AS AUTOIMUNES DEVIDO ? SUA CAPACIDADE REGENERATIVA E IMUNOMODULAT?RIA. C?LULAS-TRONCO MESENQUIMAIS (CTM) PODEM TER UM PERFIL TERAP?UTICO MELHORADO PELO USO DE ALGUMAS T?CNICAS COMO, POR EXEMPLO, O CULTIVO 3D. SENDO ASSIM, O PRESENTE ESTUDO SE PROP?S A VERIFICAR O POTENCIAL TERAP?UTICO DO SECRETOMA DE C?LULAS-TRONCO MESENQUIMAIS DO TECIDO ADIPOSO SUBCUT?NEO (CTA) CULTIVADAS EM MODELO 2D OU 3D EM CAMUNDONGOS COM DT1 INDUZIDA POR INJE??ES DE ESTREPTOZOTOCINA. AP?S TRATAMENTO, PERFIL DE CITOCINAS SECRETADAS PELAS CTAS E PROTE?NAS DO P?NCREAS (INSULINA E PDX-1) FORAM QUANTIFICADAS. N?VEIS DE IL-6 E IL-2 ENCONTRAVAM-SE AUMENTADOS NO SECRETOMA 3D, ENQUANTO IL-4 APRESENTOU-SE DIMINU?DO. SECRETOMA 2D FOI MAIS EFICAZ NA DIMINUI??O DA GLICEMIA E, TAMB?M, NO AUMENTO DA EXPRESS?O DE PDX-1 PANCRE?TICA NOS ANIMAIS DIAB?TICOS. EM CONTRA-PARTIDA, AMBOS SECRETOMAS N?O AUMENTARAM O N?VEL DE EXPRESS?O DE INSULINA. ESSES RESULTADOS DEMONSTRAM QUE O MEIO CONDICIONADO DE C?LULAS CULTIVADAS EM 3D APRESENTA UMA ALTERA??O NO SEU PERFIL IMUNOMODULAT?RIO, POR?M N?O H? UMA MELHORA NOS P?NCREAS DOS ANIMAIS DIAB?TICOS. OUTROS ESTUDOS SER?O NECESS?RIOS PARA MELHOR AVALIAR O POTENCIAL TERAP?UTICO DO SECRETOMA DESSAS C?LULAS NA DIABETES TIPO 1.
Actes de conférences sur le sujet "2D RFA model"
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Peel, Larry D., Enrique Molina, Jeff Baur et Ryan Justice. « Characterization of Shape-Changing Panels With Embedded Rubber Muscle Actuators ». Dans ASME 2012 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/smasis2012-8088.
Texte intégralRésumé :
There is great interest in making shape-changing aircraft structures that are more biomimetic. Cylindrical McKibben-like flexible actuators efficiently convert fluid pressure into mechanical energy and thus offer excellent force-to-weight ratios while behaving similar to biological muscle. McKibben-like Rubber Muscle Actuators (RMAs) were embedded into elastomer panels. The effect of actuator spacing on the performance of these shape-changing panels was investigated. The work included nonlinear finite element analysis, fabrication, and testing of panels where four RMAs were spaced side-by-side, 1/2, 1, and 1.3 RMA diameters apart. Nonlinear “Laminated Plate” and “Rod & Plate” finite element models of individual RMAs were created from existing RMA dimensions. After adjusting for an initial “activation pressure,” the models produced realistic RMA forces. The laminated plate models used less computer resources, but only produced small amounts of actuator contraction (actuator strain). The more resource-intensive Rod & Plate models better replicated fiber/braid re-orientation and produced axial strains up to 60% of test values. Three types of embedded RMA panel FEA models; a “2D Cross-Section,” a “Full 3D Panel” (with either Laminated Plate or Rod & Plate RMAs) and a “3D Unit Cell” (also with either Laminated Plate or Rod & Plate RMAs). The Full 3D Rod & Plate model gave the most accurate strains and forces, but required unsustainable levels of computing resources. The 2D cross-section model predicted optimal RMA spacing to be at 1 diameter. All other FEA models show optimal panel performance between 1/2 and 1 diameter spacing. Panels with embedded RMAs were fabricated and tested with air or water pressure. Panel force as a function of pressure and as a function of contraction (strain) was obtained. Overall, FEA and test results for panels indicate that optimal performance occurs when the RMAs are spaced between 1/2 to 1 diameter apart. Actuator force as a function of spacing is fairly flat in this region, indicating that minor design or manufacturing differences may not significantly affect performance. However, the total amount of axial contraction decreases significantly at greater than optimal spacing. Useful design, simulation, and test methodologies for embedded RMA panels have been demonstrated.
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Roldán, Alejandro, Nancy Sweitzer, Tim Osswald et Naomi Chesler. « Fluid Structure Interaction Analysis of Blood Flow Through a Mechanical Heart Valve ». Dans ASME 2008 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2008. http://dx.doi.org/10.1115/sbc2008-192585.
Texte intégralRésumé :
Modeling pulsatile flow past heart valves remains a relatively unexplored but critical area. Due to the geometric complexity and the interaction between the flowing blood and the heart valve leaflets, existing numerical techniques that require domain discretization, such as finite element methods or finite difference techniques, cannot fully represent the moving and deforming boundaries present in an operating valve. Our aim is to develop a technique to model the flow through heart valves which includes the interaction between the blood flow and the valve leaflets using the radial functions method (RFM). The RFM is a meshless technique that fully accounts for moving and deforming surfaces and thus is well suited to model the blood flow and its interaction with leaflet motion. Here we present a 2D fluid structure interaction (FSI) model of the blood flow through a bileaflet mechanical heart valve (MHV).
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Gonzalez, Andres, Zoya Heidari et Olivier Lopez. « A NEW OPTIMIZATION METHOD FOR ENHANCED FORMATION EVALUATION AND ROBUST PHYSICS-BASED AUTOMATIC ROCK CLASSIFICATION USING HIGH-RESOLUTION CT-SCAN IMAGE DATA AND CONVENTIONAL WELL LOGS ». Dans 2021 SPWLA 62nd Annual Logging Symposium Online. Society of Petrophysicists and Well Log Analysts, 2021. http://dx.doi.org/10.30632/spwla-2021-0030.
Texte intégralRésumé :
Conventional formation evaluation provides fast and accurate estimations of petrophysical properties in conventional formations through conventional well logs and routine core analysis (RCA) data. However, as the complexity of the evaluated formations increases conventional formation evaluation fails to provide accurate estimates of petrophysical properties. This inaccuracy is mainly caused by rapid variation in rock fabric (i.e., spatial distribution of rock components) not properly captured by conventional well logging tools and interpretation methods. Acquisition of high-resolution whole-core computed tomography (CT) scanning images can help to identify rock-fabric-related parameters that can enhance formation evaluation. In a recent publication, we introduced a permeability-based cost function for rock classification, optimization of the number of rock classes, and estimation of permeability. Incorporation of additional petrophysical properties into the proposed cost function can improved the reliability of the detected rock classes and ultimately improve the estimation of class-based petrophysical properties. The objectives of this paper are (a) to introduce a robust optimization method for rock classification and estimation of petrophysical properties, (b), to automatically employ whole-core two-dimensional (2D) CT-scan images and slabbed whole-core photos for enhanced estimates of petrophysical properties, (c) to integrate whole-core CT-scan images and slabbed whole-core photos with well logs and RCA data for automatic rock classification, (d) to derive class-based rock physics models for improved estimates of petrophysical properties. First, we conducted formation evaluation using well logs and RCA data for estimation of petrophysical properties. Then, we derived quantitative features from 2D CT-scan images and slabbed whole-core photos. We employed image-based features, RCA data and CT-scan-based bulk density for optimization of the number rock classes. Optimization of rock classes was accomplished using a physics-based cost function (i.e., a function of petrophysical properties of the rock) that compares class-based estimates of petrophysical properties (e.g., permeability and porosity) with core-measured properties for increasing number of image-based rock classes. The cost function is computed until convergence is achieved. Finally, we used class-based rock physics models for improved estimates of porosity and permeability. We demonstrated the reliability of the proposed method using whole-core CT-scan images and core photos from two siliciclastic depth intervals with measurable variation in rock fabric. We used well logs, RCA data, and CT-scan-based bulk-density. The advantages of using whole-core CT-scan data are two-fold. First, it provides high-resolution quantitative features that capture rapid spatial variation in rock fabric allowing accurate rock classification. Second, the use of CT-scan-based bulk density improved the accuracy of class-based porosity-bulk density models. The optimum number of rock classes was consistent for all the evaluated cost functions. Class-based rock physics models improved the estimates of porosity and permeability values. A unique contribution of the introduced workflow when compared to previously documented image-based rock classification workflows is that it simultaneously improves estimates of both porosity and permeability, and it can capture rock class that might not be identifiable using conventional rock classification techniques.