Academic literature on the topic 'Quantification semi-classique de la corde'
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Journal articles on the topic "Quantification semi-classique de la corde"
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Mihaljevic, Nikola, Slobodan Jovanovic, and Aleksandar Dlabac. "A generalized mathematical model for efficiency calibration of gamma detectors: Application to practical cases." Nuclear Technology and Radiation Protection 34, no. 1 (2019): 34–46. http://dx.doi.org/10.2298/ntrp181031006m.
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Efficiency calibration, i. e. determination of detection efficiency, ?p, is a crucial issue in gamma spectrometry (quantification of gamma spectroscopic measurements) with semiconductor and scintillation detectors. Comparing three possible ways to addressing the problem ? relative, absolute and semi empirical ? advantages of the latter are emphasized. Among semi empirical models, efficiency transfer using effective solid angles, ??, is sorted out and briefly elaborated. This approach reduces the problem of efficiency calibration to the determination of ??. It proved reliable and has been broadly used in practice, mainly in the form of the long existing ANGLE software. Progressing further, a generalized mathematical formula for calcu- lations is developed ? first of the kind ? offering an opportunity for advanced applications of gamma spectrometry. The formula enables unlimited flexibility in application, as it conveniently separates the source data from the detector data during the integration procedures ?? calculations). Its practicality is demonstrated for a number of typically encountered counting arrangements, as well as for some exotic ones. The relevant formulae are used in PC calculations and numerical testing is further performed so as to check the validity of the mathematical method and the computer code. Care was taken of the optimization of complex numerical procedures employed (involving fivefold numerical integration), so as to keep computation times as low as possible (in order of minutes or even seconds on ordinary PC). Results obtained are affirmative for both the method and the code. The model will be gradually incorporated into ANGLE software, thus making it readily available for routine use by gamma spectrometry community.
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Gulbis, Béatrice, Faustin Kagambega, Léon Tshilolo, and Françoise Vertongen. "Globin Chains Analysis: Improved Resolution by Electrophoresis in Urea—Acetic Acid—Triton X-100." Annals of Clinical Biochemistry: International Journal of Laboratory Medicine 35, no. 3 (May 1998): 415–17. http://dx.doi.org/10.1177/000456329803500311.
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To improve the resolution and rapidity of globin chains separation, we have modified the basic technique of globin chain electrophoresis in urea—acetic acid—Triton X-100. Haemolysates from anticoagulated cord or adult blood samples were submitted to urea—acetic acid-Triton X-100 Polyacrylamide gel electrophoresis using a 15% Polyacrylamide gel cast in a mini slab cell which allows a rapid analysis of globin chains samples. After staining proteins with Coomassie brilliant blue R-250, the relative amounts of globin chains were determined by scanning. This new procedure has allowed us to obtain a better separation of the normal and abnormal globin chains than described previously. All the normal globin chains, i.e. Aγ, Gγ, δ, β and α, are well separated by this modified technique. Semi-quantification of the Gγ/Aγ ratio has been performed. This simple and rapid method is also suitable for the global identification of the globin chain involved in the most common abnormal haemoglobin variants, except β-S.
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Piety, Nathaniel Z., Xiaoxi Yang, Bogdan R. Dinu, Alex George, and Sergey S. Shevkoplyas. "Paper-Based Assay for Quantification of HbS in Blood of Sickle Cell Disease Patients." Blood 124, no. 21 (December 6, 2014): 1371. http://dx.doi.org/10.1182/blood.v124.21.1371.1371.
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Abstract Introduction: Sickle cell disease (SCD) is a common inherited blood disorder caused by sickle hemoglobin (HbS) which, unlike normal adult hemoglobin (HbA), becomes insoluble and polymerizes under hypoxic conditions. Patients with SCD experience chronic hemolytic anemia, episodic pain crises and abnormal blood flow to critical organs that cumulatively result in significant illness and shortened lifespans for many. The severity of SCD varies significantly between patients, but for individuals the rate of adverse events is strongly correlated with intraerythrocytic concentration of HbS (%HbS). High per test costs and long turnaround times make conventional laboratory methods (e.g. Hb electrophoresis, HPLC, IEF) impractical for quantifying %HbS in real-time (e.g. during transfusion therapy). The objective of this study was to demonstrate that %HbS in blood could be quantified using our recently developed rapid, low-cost paper-based SCD assay [1]. Methods: Blood samples were obtained from SCD and sickle cell trait (SCT) patients at the Texas Children’s Hematology Center (Houston, TX). To perform the SCD assay a 20μL droplet of blood mixed with Hb solubility buffer (1:10 by volume) was dropped on chromatography paper. The resulting blood stain was digitized with a flatbed scanner (Canon USA Inc, Melville, NY) and analyzed using a custom image analysis code (The MathWorks Inc, Natick, MA). Conventional Hb electrophoresis was performed with the semi-automated Sebia Hydrasys 2 Scan system (Sebia Inc, Norcross, GA). Results: The difference in transport of Hb through the paper produced a blood stain with two parts: the area of the initial drop where polymerized HbS is retained (center spot) and the area where soluble Hb is wicked laterally (peripheral ring). The relative color intensity of the center spot and peripheral ring is related to the blood sample %HbS (Fig. 1). The image analysis code automatically isolates and calculates the ratio of the average color intensities of each area (S-index). A series of reconstituted blood samples with artificially adjusted %HbS from 0 to 60% was used to calibrate the assay so that %HbS could be estimated based on blood stain color intensities (Fig. 2a). The values of %HbS estimated for patient samples using our paper-based SCD assay and actual values measured using conventional Hb electrophoresis were highly correlated with R2 = 0.898 (Fig. 2b). The estimated and actual %HbS values also showed strong agreement with the standard deviation of the difference between the two measurements = 5.5 %HbS (Fig. 2c). The majority of the differences between actual and estimated %HbS (96.67%) are within 2 standard deviations of the mean of the differences. The assay could be performed in under 35 minutes and multiple assays could be performed and analyzed in parallel. The cost of consumable materials and reagents for the paper-based SCD assay is less than $0.03. Conclusions: This study demonstrates the feasibility of using our recently developed paper-based assay to quantify %HbS in blood samples in real-time. The ability to rapidly, inexpensively measure %HbS will be particularly useful for monitoring the effectiveness of chronic transfusion or hydroxyurea therapy for long-term control of HbS content in blood of SCD patients. The ability to measure %HbS in real-time could also potentially facilitate more aggressive prophylactic therapy to intervene rapidly and significantly reduce the rate of life-threatening complications in SCD patients, including stroke. Figure 1: Figure 1:. Figure 2: Figure 2:. Acknowledgments: This work was supported in part by a 2012 NIH Director's Transformative Research Award (NHLBI R01HL117329, PI: SSS). References: [1] Yang X, et al. Lab Chip, 2013, 13, 1464-1467. Disclosures Piety: Tulane University: PCT/US2012/064856 Patents & Royalties. Yang:Tulane University: PCT/US2012/064856 Patents & Royalties. Shevkoplyas:Tulane University: PCT/US2012/064856 Patents & Royalties; Halcyon Biomedical Incorporated: Equity Ownership.
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Bouheniche, Salaheddine, and Bénina Touaibia. "Modélisation numérique du transport solide du système « barrage - cours d’eau, transport - déposition » : cas du barrage de Sidi Mohamed Ben Aouda (SMBA) sur l’oued Mina, en zone semi-aride." Revue des sciences de l’eau 26, no. 1 (March 18, 2013): 21–31. http://dx.doi.org/10.7202/1014916ar.
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Résumé Les besoins en eau, en perpétuelle croissance, nécessitent une mobilisation des eaux de surface. La construction de barrages, menacés par un envasement précoce, nécessite une exploitation rationnelle, moyennant des outils d’aide à la quantification et à la prédiction des dépôts de sédiments. Ainsi, le comblement des retenues peut être simulé pour différentes périodes d’exploitation. La maîtrise du processus transport-déposition des sédiments, constitue un centre d’intérêt vers lequel convergent plusieurs approches : prédiction, modélisation stochastique et modélisations mathématique et physique. De multiples interactions existent entre les matériaux solides formant le lit, ceux transportés à proximité du fond et ceux se trouvant en suspension, se traduisant par divers modes de transport. Cette contribution présente un modèle numérique qui se prête au calcul par ordinateur dont le comportement morphologique du lit d’un cours d’eau peut être facilement simulé. Les étapes de son élaboration sont décrites avec détail, le code de calcul ainsi produit est mis en valeur sur un site test de validation. Un tronçon de 17 km est étudié, entre un barrage en exploitation et une station hydrométrique, sise à l’amont de celui-ci avec une bathymétrie à l’appui. Le transport solide dans le cours d’eau naturel est représenté par un système d’équations unidimensionnelles décrivant un mélange Eau-Sédiment et traduisant les lois de conservation. La méthode utilisée aux différences finies est appliquée, avec un schéma implicite. Elle est du premier ordre en temps et du deuxième ordre en espace. Les équations des écoulements à surface libre, en régime non permanent et graduellement varié, sont utilisées qui, associées à l’équation de continuité solide, forment le système de Saint-Venant-Exner. Une formule de charriage est utilisée pour exprimer le débit solide. Les résultats obtenus expliquent la contribution du transport solide par charriage dans le comblement de la retenue d’un barrage étudié en zone semi-aride.
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Amson, Eli. "Overall Bone Structure as Assessed by Slice-by-Slice Profile." Evolutionary Biology 46, no. 4 (October 14, 2019): 343–48. http://dx.doi.org/10.1007/s11692-019-09486-6.
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Abstract Quantifying the inner structure of bones is central to various analyses dealing with the phenotypic evolution of animals with an ossified skeleton. Computed tomography allows to assess the repartition of bone tissue within an entire skeletal element. Two parameters of importance for such analyses are the global compactness (Cg) and total cross-sectional area (Tt.Ar). However, no open-source, time-efficient methods are available to acquire these parameters for whole bones. A methodology to assess the variation of these parameters along a profile following one of the studied bone’s anatomical axes is also wanting. Here I present an ImageJ macro and associated R script to automatically acquire Cg and Tt.Ar along an axis of the skeletal element of interest using a slice-by-slice approach. No manual segmentation is required and several bones can be present on the analysed scan, as long as the bone of interest is isolated and the largest element on each slice. While some bias might be involved by the automatic acquisition, semi-automatic slice exclusion and correction procedures can be used to efficiently account for it. As a test case, µCT-data was gathered for the mid-lumbar vertebra of over 70 mammals. The two evaluated correction procedures proved to perform equally well, with a slight advantage for the one relying on the exclusion of local outliers. The presented macro allows to efficiently build a dataset concerned with the quantification of bone inner structure. The code being readily available, further improvement of the methodology and adjustment to particular needs can be easily performed.
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Li, Yangqiu, Qingsong Yin, Shaohua Chen, and Lijian Yang. "Detection of 24 TCR Vβ-Dβ1 sjTRECs in T Cells from Cord Blood, Peripheral Blood of Normal Individuals and Patients with AML-M2." Blood 106, no. 11 (November 16, 2005): 4557. http://dx.doi.org/10.1182/blood.v106.11.4557.4557.
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Abstract Thymic function is characterized its importance of thymus to T-cell diversity in the periphery of both children and adults during both health and disease. The generation of TCR diversity occurs in the thymus through recombination of gene segments encoding the variable parts of the TCRα and β chains. During these processes, by-products of the rearrangements are generated in the form of signal joint T-cell receptor excision circles (sjTRECs). As sjTRECs are stable extrachromosomal DNA fragments, are not replicated during mitosis and thus diluted with each round of cell division, and are therefore most frequent in naïve T cells that have recently left the thymus, their quantification is actually considered as a very valuable tool to estimate thymic function. Quantitative of δRec-ψJα sjTRECs can direct evaluate the recent thymic output function, but it is unable to analyze the particular thymic output function of different TCR Vβ subfamily naive T cells. The complexity of TCR Vβ repertoire is an important factor for immune reconstitution, it should be established the quantitative analysis of series TCR Vβ-Dβ sjTRECs to evaluate the levels of different Vβ subfamily naive T cells. In the present study, analysis of 24 TCR Vβ-Dβ sjTRECs was established by semi-nested PCR using 24 Vβ subfamily antisense primers and 2 Dβ1 sense primers. TCR Vβ-Dβ sjTRECs were amplified in genomic DNA from mononuclear cells of 10 cord blood samples, 10 cases of peripheral blood from normol individuals and 11 cases with AML-M2. Different amounts of DNA (corresponding to 2*105, 5*104, 1*104 and 1*103 cells respectively) from all samples were amplified to estimate the frequency of TCR Vβ-Dβ sjTRECs. The results showed that most Vβ subfamily sjTRECs could be detected in all samples from cord blood and peripheral blood at 2*105 or 5*104 cells level, some of Vβ subfamily sjTRECs could be detected in 1*103 cells level. Whereas the frequency of Vβ subfamily sjTRECs were lower in peripheral blood T cells from patients with AML-M2 than in normal individuals (p<0.05). Vβ19, Vβ23 and Vβ24 subfamily sjTRECs could not be detected in all samples at 5*104 cells level. The results indicated that Vβ subfamily naive T cells could be detected with different frequency in peripheral blood of normaol individuals as well as in some patients with AML-M2. Lower frequency of Vβ subfamily naive T cells was found in most AML-M2 patients.
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Schaefer, Daniel, Marianne Olsen, Ulrik Lausten-Thomsen, Cyrill Schipp, Martin Stanulla, Robert K. Slany, Kjeld Schmiegelow, Arndt Borkhardt, and Ute Fischer. "2% of Healthy Newborns Reveal ETV6-RUNX1 Fusion By Genomic Inverse PCR for Exploration of Ligated Breakpoints (GIPFEL)." Blood 128, no. 22 (December 2, 2016): 4082. http://dx.doi.org/10.1182/blood.v128.22.4082.4082.
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Abstract Pediatric acute lymphoblastic leukemia (ALL) is characterized by preleukemic recurrent chromosomal translocations that emerge in utero. The translocation t(12;21) resulting in the formation of the chimeric transcription factor ETV6-RUNX1 is the most frequent structural aberration occurring in 25% of B-cell precursor patients. A previous study suggested that ETV6-RUNX1-positive preleukemic cells are present in every hundredth human newborn, thus exceeding the actually observed incidence of ETV6-RUNX1-positive ALL in children (1/10,000) by a factor of 100. This finding strongly indicated that secondary cooperating oncogenic hits were necessary for development of overt leukemia. However, later studies could not confirm this high frequency. To analyze the actual frequency of ETV6-RUNX1 preleukemic cells in newborns we developed a PCR-based method termed genomic inverse PCR for exploration of ligated breakpoints (GIPFEL) and applied this technique to a population-based retrospective screening of 300 cord blood samples from Danish newborns. The GIPFEL method is capable of detecting the most common gene fusions associated with childhood leukemia without prior knowledge of the exact breakpoint. In contrast to previously used RNA-based methods, it relies on DNA as sample material, which is more stable than RNA. In the case of ETV6-RUNX1-positive leukemia GIPFEL exploits the unique presence of a genomic fragment joining material from chromosome 12 and 21. These fragments can be digested and re-circularized by ligation creating a junction across the restriction site whose sequence can be predicted from published genome data. The ligation site is independent of the translocation point within the individual DNA circle. Digestion of the breakpoint regions of the ETV6 and RUNX1 gene with the restriction enzyme SacI generates fragments smaller than 50 kb. Primer pairs amplify the complete set of theoretically predicted circularized fragments requiring 37 primers for the ETV6-RUNX1 translocation. Genomic DNA was prepared from mononuclear cells from cord blood samples of 300 newborns that were cryopreserved within 24 h (median 12 h) from birth. After B cell enrichment and column purification of DNA, the DNA was subjected to SacI restriction digest, ligated and remaining linear DNA was removed by exonuclease III. After ethanol precipitation the reaction products were subjected to a partially multiplexed, semi-nested PCR to quantify all possible ligation/junction products specific for the translocation. Samples that screened positive underwent one further demultiplexed PCR, agarose gelelectrophoresis and Sanger sequencing to validate the result and to identify the breakpoint region. An internal RUNX1 genomic ligation product served as a quality control and allowed the relative quantification of the translocation product. In previously published proof-of-principle blinded studies we tested 61 samples obtained from ETV6-RUNX1-positive ALL patients. Without any unspecific result, 64% for ETV6-RUNX1 fusion genes were detected in that sample set. The sensitivity of the technique was estimated to be 10-4, i.e. one translocation carrying cell within 10,000 normal cells can theoretically be detected. Within the analyzed cohort of 300 healthy newborns 6 screened positive for the ETV6-RUNX1 translocation (2%) (Table 1). Further 700 cord blood samples are currently screened. Table 1: 6 of 300 cord blood samples from healthy newborns screened positive for the ETV6-RUNX1 translocation using the GIPFEL technique (Fueller E*, Schaefer D* et al. PloS One 2014, 9(8): e104419). Number of the positively tested healthy newborn within the cohort, used primers, and introns of RUNX1 and ETV6 affected by the translocation are presented. Our results indicate that the actual incidence of ETV6-RUNX1-positive cells in healthy newborns might be even higher than previously assumed, potentially due to instability of the ETV6-RUNX1 RNA transcript in preserved cord blood samples. This would hint at a comparably low penetrance and leukemia inducing potential of the chimeric transcription factor ETV6-RUNX1 in human newborns and further strengthen the importance of secondary environmentally caused or spontaneously occurring cooperating oncogenic lesions for ETV6-RUNX1-positive childhood leukemia to emerge. Table Table. Disclosures No relevant conflicts of interest to declare.
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Fischer, Ute, Daniel Schäfer, Elisa Füller, Katrine Ask, Pina Fanny Ida Krell, Martin Stanulla, Marianne Olsen, Kjeld Schmiegelow, Robert K. Slany, and Arndt Borkhardt. "Gipfel – a Novel Method for Unbiased Molecular ETV6-RUNX1 Screening of Healthy Newborns." Blood 124, no. 21 (December 6, 2014): 5340. http://dx.doi.org/10.1182/blood.v124.21.5340.5340.
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Abstract Pediatric acute lymphoblastic leukemia (ALL) is characterized by recurrent chromosomal translocations that frequently occur in utero in preleukemic cells. The translocation t(12;21) resulting in the formation of the chimeric transcription factor ETV6-RUNX1 is the most frequent structural aberration occurring in 25% of B-cell ALL. A previous study suggested that ETV6-RUNX1 positive preleukemic cells are present in every hundredth human newborn, thus exceeding the actually observed incidence of ETV6-RUNX1 positive ALL in children by a factor of 100. This finding indicated that secondary, but relatively rare cooperating oncogenic hits are necessary for the development of overt leukemia. However, later studies could not confirm this high incidence of preleukemic cells in newborns. To analyze the actual frequency of ETV6-RUNX1 preleukemic cells in newborns we developed a PCR based method termed genomic inverse PCR for exploration of ligated breakpoints (GIPFEL) and applied this technique to a population-based screening of ≈1000 cord blood samples from healthy newborns. The GIPFEL method is capable to detect the most common gene fusions associated with childhood leukemia without prior knowledge of the exact breakpoint. In the case of ETV6-RUNX1 positive leukemia, GIPFEL exploits the unique presence of a genomic fragment joining material from chromosomes 12 and 21 in the translocation-positive cells. These fragments can be digested and re-circularized by ligation creating a junction across the restriction site whose sequence can be predicted from published genome data. Importantly, the ligation site is independent of the translocation point within the individual DNA circle. The published breakpoint regions of the ETV6 and RUNX1 genes involved in the translocation were analyzed in silico for restriction sites that allow digestion of all possible translocation events to yield fragments smaller than approximately 50 kb. This condition was met for ETV6-RUNX1 breakpoints by digestion with SacI. Primer pairs were designed amplifying the complete set of theoretically predicted circularized fragments requiring 36 primers for the ETV6-RUNX1 translocation. Genomic DNA was prepared from cell lines, diagnostic specimens from ALL patients, peripheral blood from healthy donors and cord blood samples from newborns by column purification. The equivalent of approximately 4x105 cells (2.5 µg DNA) was subjected to the SacI restriction digest, ligated and remaining linear DNA was removed by exonuclease III. After ethanol precipitation the reaction products were subjected to a partially multiplexed, semi-nested PCR to quantify all possible ligation/junction products specific for the translocation. An internal RUNX1 genomic ligation product served as a quality control and allowed the relative quantification of the translocation product. In a first proof-of-principle study employing the ETV6-RUNX1 translocation positive cell line REH, process optimization close to the theoretical limits was carried out. Cell dilution and mixing studies revealed that under optimal conditions approximately 40 translocation positive cells (=10-4) present in the input DNA are sufficient to produce a reliable output signal. The method was next tested in a blinded study with 60 samples obtained from ETV6-RUNX1 diagnostic ALL samples. ETV6-RUNX1 samples positive at 10-4, being diluted from these diagnostic samples, still gave a reliable output signal. There was no false positive result. Detection coverage (=sensitivity) was 64%. This method was then applied to a retrospective sample set of cryopreserved anonymized cord blood samples of ≈1000 healthy newborns to determine frequency and levels of translocation-positive cells. First results will be presented. In conclusion this population-based study will allow an estimate of the actual incidence of ETV6-RUNX1 positive preleukemic cells in healthy newborns. The results will enable us to evaluate the penetrance and leukemia inducing potential of the chimeric transcription factor ETV6-RUNX1 in human newborns and will provide a basis for the assessment of potential secondary environmental or spontaneously occurring cooperating oncogenic lesions in ETV6-RUNX1 positive childhood leukemia. Disclosures No relevant conflicts of interest to declare.
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Ermolli, I., K. Matthes, T. Dudok de Wit, N. A. Krivova, K. Tourpali, M. Weber, Y. C. Unruh, et al. "Recent variability of the solar spectral irradiance and its impact on climate modelling." Atmospheric Chemistry and Physics 13, no. 8 (April 17, 2013): 3945–77. http://dx.doi.org/10.5194/acp-13-3945-2013.
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Abstract. The lack of long and reliable time series of solar spectral irradiance (SSI) measurements makes an accurate quantification of solar contributions to recent climate change difficult. Whereas earlier SSI observations and models provided a qualitatively consistent picture of the SSI variability, recent measurements by the SORCE (SOlar Radiation and Climate Experiment) satellite suggest a significantly stronger variability in the ultraviolet (UV) spectral range and changes in the visible and near-infrared (NIR) bands in anti-phase with the solar cycle. A number of recent chemistry-climate model (CCM) simulations have shown that this might have significant implications on the Earth's atmosphere. Motivated by these results, we summarize here our current knowledge of SSI variability and its impact on Earth's climate. We present a detailed overview of existing SSI measurements and provide thorough comparison of models available to date. SSI changes influence the Earth's atmosphere, both directly, through changes in shortwave (SW) heating and therefore, temperature and ozone distributions in the stratosphere, and indirectly, through dynamical feedbacks. We investigate these direct and indirect effects using several state-of-the art CCM simulations forced with measured and modelled SSI changes. A unique asset of this study is the use of a common comprehensive approach for an issue that is usually addressed separately by different communities. We show that the SORCE measurements are difficult to reconcile with earlier observations and with SSI models. Of the five SSI models discussed here, specifically NRLSSI (Naval Research Laboratory Solar Spectral Irradiance), SATIRE-S (Spectral And Total Irradiance REconstructions for the Satellite era), COSI (COde for Solar Irradiance), SRPM (Solar Radiation Physical Modelling), and OAR (Osservatorio Astronomico di Roma), only one shows a behaviour of the UV and visible irradiance qualitatively resembling that of the recent SORCE measurements. However, the integral of the SSI computed with this model over the entire spectral range does not reproduce the measured cyclical changes of the total solar irradiance, which is an essential requisite for realistic evaluations of solar effects on the Earth's climate in CCMs. We show that within the range provided by the recent SSI observations and semi-empirical models discussed here, the NRLSSI model and SORCE observations represent the lower and upper limits in the magnitude of the SSI solar cycle variation. The results of the CCM simulations, forced with the SSI solar cycle variations estimated from the NRLSSI model and from SORCE measurements, show that the direct solar response in the stratosphere is larger for the SORCE than for the NRLSSI data. Correspondingly, larger UV forcing also leads to a larger surface response. Finally, we discuss the reliability of the available data and we propose additional coordinated work, first to build composite SSI data sets out of scattered observations and to refine current SSI models, and second, to run coordinated CCM experiments.
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Kim, Jung Hwan, Garrett W. Astary, Xiaoming Chen, Thomas H. Mareci, and Malisa Sarntinoranont. "Voxelized Model of Interstitial Transport in the Rat Spinal Cord Following Direct Infusion Into White Matter." Journal of Biomechanical Engineering 131, no. 7 (July 1, 2009). http://dx.doi.org/10.1115/1.3169248.
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Direct tissue infusion, e.g., convection-enhanced delivery (CED), is a promising local delivery technique for treating diseases of the central nervous system. Predictive models of spatial drug distribution during and following direct tissue infusion are necessary for treatment optimization and planning of surgery. In this study, a 3D interstitial transport modeling approach in which tissue properties and anatomical boundaries are assigned on a voxel-by-voxel basis using tissue alignment data from diffusion tensor imaging (DTI) is presented. The modeling approach is semi-automatic and utilizes porous media transport theory to estimate interstitial transport in isotropic and anisotropic tissue regions. Rat spinal cord studies compared predicted distributions of albumin tracer (for varying DTI resolution) following infusion into the dorsal horn with tracer distributions measured by Wood et al. in a previous study. Tissue distribution volumes compared favorably for small infusion volumes (<4 μl). The presented DTI-based methodology provides a rapid means of estimating interstitial flows and tracer distributions following CED into the spinal cord. Quantification of these transport fields provides an important step toward development of drug-specific transport models of infusion.
Dissertations / Theses on the topic "Quantification semi-classique de la corde"
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Vieira, Pedro. "Intégralité en AdS/CFT : ansatz de Bethe et quantification de corde au delà du volume infini." Paris 6, 2008. http://www.theses.fr/2008PA066378.
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Dans cette thèse l'intégrabilité dans AdS/CFT est passée en revue. La technique de l'ansatz de Bethe est presentée et les équations de Bethe à toutes les boucles sont discutées. Du coté de la théorie des cordes, la méthode classique des bandes-finies est revisitée et une attention particulière est accordée à la quantification semi-classique de la supercorde. Les méthodes basées sur la courbe algébrique sont très générales et fournissent des contraintes fortes sur les équations quantiques. De telles contraintes sont explorées en detail pour la dualité AdS5/CFT4 bien qu'elles soient générales et valables, entre autres, pour le système AdS4/CFT3. Ces techniques permettent aussi d'étudier le système au delà de la limite de volume infini quand l'ansatz de Bethe asymptotique n'est plus valableIn this thesis Integrability in AdS/CFT is reviewed. Bethe ansatz techniques are presented and the all loop Bethe equations are discussed. From the string side of the correspondence, the classical finite-gap method is revisited and special emphasis is given to the super-string semi-classical quantization. The algebraic curve methods are quite general and provide very important constraints on the full quantum equations. The formalism is extremely versatile and can be applied to the AdS5/CFT4 duality the most studied case in this work -- as well as to other integrable systems like e. G. The AdS4/CFT3 correspondence. Furthermore, these techniques yield valuable information about the spectrum of finite charge states when the asymptotic Bethe ansatz is no longer valid
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Detcherry, Renaud. "Analyse semi-classique des opérateurs courbes en TQFT." Thesis, Paris 6, 2015. http://www.theses.fr/2015PA066252/document.
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Witten, Reshetikhin et Turaev ont défini des invariants des variétés topologiques de dimension 3, dits "quantiques" qui s'étendent en une structure de TQFT, c'est-à-dire un foncteur monoïdal d'une catégorie de cobordismes vers la catégorie des espaces vectoriels complexes. Nous étudions ici leur asymptotique. Dans ce cadre, les courbes sur une surface induisent des endomorphismes des espaces de TQFT, appelés opérateurs courbes, qui sont l'un des objets centraux du mémoire. Tous ces invariants dépendant d'un paramètre entier r, on s'intéresse à leur comportement quand r tend vers l'infini. On s'aperçoit alors que les invariants quantiques sont liés à des objets plus géométriques, comme les espaces des modules des représentations dans SU2 du groupe fondamental d'une surface. La première partie de la thèse introduit la notion de TQFT et les invariants de Witten-Reshetikhin-Turaev, puis donne des rudiments de géométrie de l'espace des modules SU2 d'une surface et de quantification géométrique. La deuxième partie présente un résultat sur l'asymptotique des coefficients de matrices des opérateurs courbes en TQFT. A partir de calcul d'écheveau et d'un théorème de Bullock, on relie les deux premiers termes de leur développement aux fonctions traces associées aux multicourbes. Cette thèse aboutit dans la troisième partie à un résultat asymptotique pour les coefficients de matrices des représentations quantiques. Un modèle géométrique est proposé pour les espaces de TQFT associés aux surfaces, et il est montré que les opérateurs courbes s'identifient alors à des opérateurs de Toeplitz. Des méthodes standards d'analyse semi-classiques permettent d'en déduire le résultatIn this thesis we study the asymptotics of some invariants of 3-manifolds, known as "quantum invariants" which were defined by Witten, Reshetikhin and Turaev. These invariants are part of a TQFT structure, that is a monoidal functor for a category of cobordism to the category of complex vector spaces. In this setting, curves on surfaces induce endomorphisms of TQFT vector spaces, called curve operators, which are one of the main object in our study. All these invariants depend of an integer parameter r, and we are interested in their behavior when r tends to infinity. We can then see that quantum invariants are related to more geometric objects, like the moduli space of conjugacy classes of SU2 representations of the fundamental group of a surface. The thesis is divided in 3 parts: in the first one we introduce the notion of TQFT and the Witten-Reshetikhin-Turaev invariants, then we give basic properties of the SU2-moduli spaces and explain the general approach of geometric quantification. In the second one we present a result on the asymptotics of matrix coefficients of curve operators. Using skein calculus and a theorem of Bullock, we express the first two terms of their expansion in terms of trace functions on the SU2-moduli space associated to multicurves. The final part gives an asymptotic expansion of matrix coefficents of quantum representations. A geometric model for TQFT vector spaces is defined, and we show that curve operators can be seen as Toeplitz operators in this model. Standard tools of semi-classical analysis allow us to deduce the result from this
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Louati, Hanen. "Règles de quantification semi-classique pour une orbite périodique de type hyberbolique." Thesis, Toulon, 2017. http://www.theses.fr/2017TOUL0004/document.
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On étudie les résonances semi-excitées pour un Opérateur h-Pseudo-différentiel (h-PDO)H(x, hDx) sur L2(M) induites par une orbite périodique de type hyperbolique à l’énergie E = 0. Par exemple M = Rn et H(x, hDx; h) est l’opérateur de Schrödinger avec effet Stark, ouH(x, hDx; h) est le flot géodesique sur une variété axi-symétrique M, généralisant l’exemplede Poincaré de systèmes Lagrangiens à 2 degrés de liberté. On étend le formalisme de Gérard and Sjöstrand, au sens où on autorise des valeurs propres hyperboliques et elliptiques del’application de Poincaré, et où l’on considère des résonances dont la partie imaginaire est del’ordre de hs, pour 0 < s < 1.On établit une règle de quantification de type Bohr-Sommerfeld au premier ordre en fonction des nombres quantiques longitudinaux (réels) et transverses (complexes), incluantl’intégrale d’action le long de l’orbite, la 1-forme sous-principale, et l’indice de Conley-ZehnderIn this Thesis we consider semi-excited resonances for a h-Pseudo-Differential Operator (h-PDO for short) H(x, hDx; h) on L2(M) induced by a periodic orbit of hyperbolic type at energy E = 0, as arises when M = Rn and H(x, hDx; h) is Schrödinger operator withAC Stark effect, or H(x, hDx; h) is the geodesic flow on an axially symmetric manifold M,extending Poincaré example of Lagrangian systems with 2 degree of freedom. We generalizethe framework of Gérard and Sjöstrand, in the sense that we allow for hyperbolic and ellipticeigenvalues of Poincaré map, and look for (excited) resonances with imaginary part of magnitude hs, with 0 < s < 1,It is known that these resonances are given by the zeroes of a determinant associatedwith Poincaré map. We make here this result more precise, in providing a first order asymptoticsof Bohr-Sommerfeld quantization rule in terms of the (real) longitudinal and (complex)transverse quantum numbers, including the action integral, the sub-principal 1-form and Gelfand-Lidskii index
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Laleg, Taous-Meriem. "Analyse de signaux par quantification semi-classique. Application à l'analyse des signaux de pression artérielle." Phd thesis, Université de Versailles-Saint Quentin en Yvelines, 2008. http://tel.archives-ouvertes.fr/tel-00357309.
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Cette thèse introduit une nouvelle méthode d'analyse de signaux, appelée SCSA, basée sur une quantification semi-classique. L'idée principale de la SCSA consiste à interpréter un signal en forme d'impulsions comme un puits de potentiel pour une particule semi-classique et à le représenter par les niveaux d'énergie discrets associés donnés par le spectre discret d'un opérateur de Schrödinger. La SCSA est une première étape vers une approximation par solitons (potentiels sans réflexion), qui définit une représentation parcimonieuse du signal, intéressante pour des applications en traitement du signal, par exemple la compression de données. Ce travail propose aussi un algorithme numérique pour l'estimation de signaux par la SCSA et présente les résultats de l'analyse des signaux de pression artérielle par cette méthode. En plus de la reconstruction satisfaisante de ces signaux, la SCSA introduit de nouveaux indices qui semblent véhiculer des informations physiologiques importantes.
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Laleg, Kirati Taous-Meriem. "Analyse de signaux par quantification semi-classique : application à l'analyse des signaux de pression artérielle." Versailles-St Quentin en Yvelines, 2008. http://www.theses.fr/2008VERS0041.
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This thesis introduces a new signal analysis method called SCSA, based on a semi-classical quantification. The main idea in the SCSA consists in interpreting a pulse-shaped signal as a potential well for a semi-classical particle and to represent this signal with the associated discrete energy levels given by the discrete spectrum of a Schrödinger operator. The SCSA is in fact a first step to an approximation by solitons (reflectionless potentials), which introduces a parsimonious representation of a signal, interesting in signal analysis applications for example for data compression. This work proposes also a numerical algorithm for signals estimation using the SCSA and presents the results obtained for the analysis of the arterial blood pressure with this method. More than a satisfactory estimation of the pressure signals, the SCSA introduces new indices that seem to contain important physiological informationCette thèse introduit une nouvelle méthode d'analyse de signaux, appelée SCSA, basée sur une quantification semi-classique. L'idée principale de la SCSA consiste à interpréter un signal en forme d’impulsions comme un puits de potentiel pour une particule semi-classique et à le représenter par les niveaux d’énergie discrets associés donnés par le spectre discret d’un opérateur de Schrödinger. La SCSA est une première étape vers une approximation par solitons (potentiels sans réflexion), qui définit une représentation parcimonieuse du signal, intéressante pour des applications en traitement du signal, par exemple la compression de données. Ce travail propose aussi un algorithme numérique pour l’estimation de signaux par la SCSA et présente les résultats de l’analyse des signaux de pression artérielle par cette méthode. En plus de la reconstruction satisfaisante de ces signaux, la SCSA introduit de nouveaux indices qui semblent véhiculer des informations physiologiques importantes
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CHARLES, Laurent. "Aspects semi-classiques de la quantification géométrique." Phd thesis, Université Paris Dauphine - Paris IX, 2000. http://tel.archives-ouvertes.fr/tel-00001289.
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Dans cette thèse, nous étudions les opérateurs de Berezin-Toeplitz sur les variétés kähleriennes et leur généralisation aux variétés symplectiques compactes. Le premier chapitre porte sur l'intégrale de Feynman : nous exprimons le noyau du propagateur quantique à l'aide d'une intégrale de Wiener en fonction de l'action classique. Dans le second chapitre, nous proposons un ansatz pour le noyau des opérateurs de Berezin-Toeplitz, grâce auquel on donne une preuve directe des résultats connus sur ces opérateurs et l'on décrit le calcul des symboles covariants et contravariants en fonction de la métrique kählerienne. Ceci mène à la définition de plusieurs star-produits sur les variétés kähleriennes par une formule universelle. Dans le troisième chapitre, nous généralisons l'ansatz précédent afin de quantifier les sous-variétés lagrangiennes des variétés kähleriennes. Nous appliquons ceci de diverses manières : construction de quasi-modes, énoncé des conditions de Bohr-Sommerfeld, quantification des symplectomorphismes, réalisation d'équivalence microlocale. En comparaison avec la théorie des opérateurs pseudodifférentiels, les invariants de la géométrie des cotangents sont remplacés par des invariants de la géométrie kählerienne. Dans le dernier chapitre, nous entreprenons la généralisation des résultats précédents aux variétés symplectiques compactes, notamment nous quantifions les sous-variétés lagrangiennes et décrivons le calcul symbolique des opérateurs de Berezin-Toeplitz.
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Rouby, Ophélie. "Conditions de quantification de Bohr-Sommerfeld pour des opérateurs semi-classiques non auto-adjoints." Thesis, Rennes 1, 2016. http://www.theses.fr/2016REN1S051/document.
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On s'intéresse à la théorie spectrale d'opérateurs semi-classiques non auto-adjoints en dimension un et plus précisément aux développements asymptotiques des valeurs propres. Ces derniers font intervenir des objets géométriques issus de la mécanique classique dans l'espace des phases complexifié et correspondent à une généralisation des conditions de quantification de Bohr-Sommerfeld au cadre non auto-adjoint. Plus précisément, dans un premier temps, on étudie le spectre de perturbations non auto-adjointes d'opérateurs pseudo-différentiels auto-adjoints en dimension un à l'aide de techniques d'analyse microlocale analytique et en corollaire, on établit que pour des perturbations PT-symétriques d'opérateurs auto-adjoints, le spectre est réel. Ensuite, on présente des conditions de quantification de Bohr-Sommerfeld pour des perturbations non auto-adjointes d'opérateurs de Berezin-Toeplitz du plan complexe auto-adjoints. Dans un second temps, on s'intéresse aux différentes quantifications du tore et plus précisément à la quantification de Berezin-Toeplitz du tore, à la quantification de Weyl classique du tore et à la quantification de Weyl complexe du tore. On établit des liens entre ces différentes quantifications notamment grâce à la transformée de Bargmann, puis à l'aide de simulations numériques, on met en évidence une conjecture sur des conditions de quantification de Bohr-Sommerfeld pour des perturbations non auto-adjointes d'opérateurs de Berezin-Toeplitz du tore auto-adjointsWe interest ourselves in the spectral theory of non self-adjoint semi-classical operators in dimension one and in asymptotic expansions of eigenvalues. These expansions are written in terms of geometrical objects in a complex phase space coming from classical mechanics and correspond to a generalization of Bohr-Sommerfeld quantization conditions in the non self-adjoint case. First, we study non self-adjoint perturbations of self-adjoint pseudo-differential operators in dimension one by using techniques of analytic microlocal analysis. As a corollary, we establish for PT-symmetric perturbations of self-adjoint operators, that the spectrum is real. Then we show Bohr-Sommerfeld quantization conditions for non self-adjoint perturbations of self-adjoint Berezin-Toeplitz operators of the complex plane. In the second part, we look into quantizations of the torus, namely the Berezin-Toeplitz, the classical Weyl and the complex Weyl quantizations of the torus. We establish links between these different quantizations using Bargmann transform. We propose a conjecture, supported by numerical simulations, on Bohr-Sommerfeld quantization conditions for non self-adjoint perturbations of self-adjoint Berezin-Toeplitz operators of the torus
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Boisseau, Christophe. "Interactions d'atomes ultra froids - extension de la notion de seuil quantique et correction de la condition de quantification semi-classique pour les niveaux vibrationnels proches de la limite de dissociation - deplacement lumineux pour une paire d'atomes." Toulouse 3, 1999. http://www.theses.fr/1999TOU30018.
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Ce travail porte sur l'etude des interactions entre deux atomes ultra froids. Pour cela nous utilisons le lien entre la longueur de diffusion (parametre critique de la condensation de bose-einstein) et le dephasage asymptotique induit par le potentiel interatomique. Nous etablissons une expression asymptotique de la fonction d'onde dans le formalisme phase-amplitude, qui permet de prolonger analytiquement l'approximation semi-classique dans la zone energetique du seuil quantique. Nous montrons qu'il est possible d'utiliser cette expression avec des potentiels modeles pour la simulation numerique d'une experience de photoassociation grace a l'approximation de la reflexion et nous testons la validite de cette approximation qui se revele excellente dans de nombreux cas. Nous avons d'autre part etendu la notion de seuil quantique aux niveaux vibrationnels de tres faible energie de liaison. En effet, comme pour les etats du continuum, ils apparaissent dans un domaine energetique caracterise par une limitation de la validite de l'approximation semi-classique. Grace a un code de calcul que nous avons developpe pour determiner precisement la position energetique de ces niveaux, nous montrons que la condition de quantification wkb doit etre corrigee par un terme de phase supplementaire dans cette zone energetique. Nous decrivons ensuite analytiquement ce terme dans le cas d'etats lies extremement proches de la limite de dissociation. L'ensemble de ces resultats a demande un gros travail de programmation numerique pour le calcul des fonctions d'onde dans des domaines inhabituels en physique moleculaire (tres basses energies, tres grandes distances internucleaire). Enfin, dans le cadre des reseaux optiques, nous etudions l'interaction entre deux atomes en presence d'un champ laser. L'anisotropie de cette interaction est mise en evidence. Le resultat le plus important est que la presence simultanee des deux atomes dans un meme micro-piege detruit l'effet de piegeage.
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Puchol, Martin. "Inégalités de Morse holomorphes G-invariantes et formes de torsion asymptotiques." Sorbonne Paris Cité, 2015. http://www.theses.fr/2015USPCC191.
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Dans cette thèse, nous étudions certains aspects de la limite semi-classique en géométrie complexe. Soit M une variété complexe munie d'un fibré en droites holomorphe L et d'un fibré complexe E. Nous donnons les propriétés asymptotiques d'objets associés aux grandes puissances tensorielles de L tordues par E. Dans le premier chapitre, M est compacte, L positif et E pas nécessairement holomorphe. Nous montrons l'annulation des 2j premiers termes du développement asymptotique diagonal du noyau de Bergman restreint aux (0,2j)-formes puis nous donnons une formule locale pour les coefficients dominants. Dans le deuxième chapitre, M est compacte, E holomorphe et un groupe de Lie compact connexe agit sur M, L et E de façon compatible. Nous établissons des inégalités de Morse holomorphes analogues à celles de Demailly pour la partie invariante de la cohomologie de Dolbeault. Pour cela, nous définissons, sous une hypothèse naturelle, la réduction de M et nous donnons nos inégalités en termes de la courbure du fibré induit par L sur cette réduction. Dans le troisième chapitre, E est holomorphe et M est l'espace total d'une fibration holomorphe de fibre compacte. On peut alors définir les formes de torsion analytique holomorphe associées à cette fibration et aux puissances de L tordues par E. Nous donnons d'abord une formule asymptotique pour ces formes, que nous généralisons ensuite dans le cas où les puissances de L sont remplacées par l'image directe des puissances d'un fibré en droites sur une variété plus grosse. Dans les deux cas, nous devons faire des hypothèses de positivité sur le fibré en droites. Ces résultats sont les versions en famille des résultats de Bismut-VasserotIn this thesis, we study some aspects of the semi-classical lirait in complex geometry. Let M be a complex manifold, endowed with a holomorphic line bundle L and a complex bundle E. We give here the asymptotic properties of several objects associated with the high tensor powers of L, twisted by E. In the first chapter, M is compact, L positive and E non necessarily holomorphic. We prove the cancellation of the first 2j terms in the diagonal asymptotic expansion of the restriction to the (0, 2j)-forms of the Bergman kernel. Then, we give a local formula for the leading coefficients. In the second chapter, M is compact, E holomorphic and a connected compact Lie group acts on M, L and E in a compatible way. We establish asymptotic holomorphic Morse inequalities à la Demailly for the invariant part of the Dolbeault cohomology. To do so, we define the reduction of M under natural hypothesis and give our inequalities in terms of the curvature of the bundle induced by L on this reduction. In the third chapter, E is holomorphic and Mis the total space of a holomorphic fibration with compact fibers. We can then define the holomorphic analytic torsion forms associated with this fibration and the tensor powers of L, twisted by E. We first give an asymptotic formula for these forms. Secondly, we generalize this formula in the case where the powers of L are replaced by the direct image of powers of a line bundle on a bigger manifold. In both cases we have to make positivity assumptions on the line bundle. These results are the family versions of the results of Bismut-Vasserot
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Le, Floch Yohann. "Théorie spectrale inverse pour les opérateurs de Toeplitz 1D." Phd thesis, Université Rennes 1, 2014. http://tel.archives-ouvertes.fr/tel-01065441.
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Dans cette thèse, nous prouvons des résultats de théorie spectrale, directe et inverse, dans la limite semi-classique, pour les opérateurs de Toeplitz autoadjoints sur les surfaces. Pour les opérateurs pseudo-différentiels, les résultats en question sont déjà connus, et il est naturel de vouloir les étendre aux opérateurs de Toeplitz. Les conditions de Bohr-Sommerfeld usuelles, qui caractérisent les valeurs propres proches d'une valeur régulière du symbole principal, ont été obtenues il y a quelques années seulement pour les opérateurs de Toeplitz. Notre contribution consiste en l'extension de ces conditions près de valeurs critiques non dégénérées. Nous traitons le cas d'une valeur critique elliptique à l'aide d'une technique de forme normale ; l'opérateur modèle est la réalisation de l'oscillateur harmonique sur l'espace de Bargmann, dont le spectre est bien connu. Dans le cas d'une valeur critique hyperbolique, la forme normale ne suffit plus et nous complétons l'étude en faisant appel à des arguments dus à Colin de Verdière et Parisse, à qui l'on doit le résultat analogue dans le cas pseudo-différentiel. Enfin, nous établissons un résultat de théorie spectrale inverse pour les opérateurs de Toeplitz autoadjoints sur les surfaces ; plus précisément, nous montrons que sous certaines hypothèses génériques, la connaissance du spectre à l'ordre deux dans la limite semi-classique permet de retrouver le symbole principal à symplectomorphisme près. Ce résultat s'appuie en grande partie sur l'écriture des règles de Bohr-Sommerfeld.
Book chapters on the topic "Quantification semi-classique de la corde"
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Pezold, Simon, Michael Amann, Katrin Weier, Ketut Fundana, Ernst W. Radue, Till Sprenger, and Philippe C. Cattin. "A Semi-automatic Method for the Quantification of Spinal Cord Atrophy." In Lecture Notes in Computational Vision and Biomechanics, 143–55. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-07269-2_13.
Full textConference papers on the topic "Quantification semi-classique de la corde"
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Van Uitert, Robert, Ingmar Bitter, and John A. Butman. "Semi-automatic segmentation and quantification of 3D spinal cord data." In Medical Imaging, edited by Armando Manduca and Amir A. Amini. SPIE, 2006. http://dx.doi.org/10.1117/12.653266.
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Aydogan, Fatih. "Verification, Validation and Uncertainty Quantification of a Nuclear Thermal Hydraulics Code." In ASME 2013 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/imece2013-63021.
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Nuclear thermal hydraulics codes are used in designing next generation systems and analyzing existing designs. Since most of the nuclear safety analyses employ nuclear thermal hydraulics codes, every step of the development in these codes are carefully verified and validated (V&V). This study shows the V&V steps of uncertainty equations implemented into the nuclear safety code of Coolant Boiling in Rod Arrays Code-Two-Fluid (COBRA-TF). COBRA-TF, designed by Pacific Northwest Laboratory, represents a two-fluid, three-field (continuous liquid, continuous vapor and entrained liquid drop) representation of two-phase flow. For heat transfer from and within the solid structures in contact with the fluid, a finite difference and semi-implicit numerical technique on an Eulerian mesh is used to solve conservation equations for each of the three fields. Even though the code is capable of predicting two-phase flow response of a system, it only predicts deterministic results without uncertainty bounds. Therefore, uncertainty equations based on Aydogan’s sampling uncertainty method are implemented into COBRA-TF to obtain uncertainty bounds of code predictions. The V&V steps of US-NRC’s Regulatory Guide 1.203 (Rg 1.203) are followed as a guideline after the code updates. Several code-to-data comparisons are done in the process of V&V: single phase pressure drop, two phase pressure drop, void distribution, critical power and dry-out location. Uncertainty bounds of code predictions are calculated and compared with the experimental uncertainty bounds. An experimental database which covers various two phase flow experiments, boundary conditions (mass flow rate, pressure and inlet enthalpies), 1/1 scale nuclear fuel bundles, axial and radial power distribution is selected for the purpose of this study. The uncertainty results of new uncertainty equations coded in COBRA-TF are satisfying.
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Gonzalez, Andres, Mehdi Teymouri, Zoya Heidari, and Olivier Lopez. "ANISOTROPY QUANTIFICATION USING HIGH-RESOLUTION WHOLE-CORE CT-SCAN IMAGES." In 2021 SPWLA 62nd Annual Logging Symposium Online. Society of Petrophysicists and Well Log Analysts, 2021. http://dx.doi.org/10.30632/spwla-2021-0087.
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Spatial anisotropy and heterogeneity in petrophysical properties can significantly affect formation evaluation of hydrocarbon bearing formations. A common example is permeability anisotropy, which is a consequence of the depositional mechanisms of sediments. Additionally, the variation in spatial distribution of rock components and the effect of post-depositional processes on the physical and chemical structure of the rock constituents can strongly impact the directional dependency of petrophysical, electrical, and elastic properties. Therefore, image-based quantification of spatial distribution of rock constituents can be used for anisotropy evaluation. Assessment of anisotropy has been previously accomplished through use of pore-scale images. However, the discrete nature of this images gives a narrow picture of anisotropy in larger scales. Whole-core computed tomography (CT) scan images, despite revealing the distribution of rock components at a coarser scale, provide a continuous medium for anisotropy estimation. Assessment of anisotropy using three-dimensional (3D) CT-scan data and incorporation of that information in well-log-based formation evaluation is, however, not widely studied or practiced in the petroleum industry. The objectives of this paper are (a) to develop a method to quantify anisotropy utilizing whole-core 3D CT-scan image stacks, (b) to provide a semi-continuous measure of rock anisotropy, and (c) to show the value of the proposed method by means of estimation of directional-dependent elastic properties. First, we pre-process the raw whole-core CT-scan images to remove undesired image artifacts and to generate an image containing pixels representing only the recovered core material. Then, we segment each whole-core CT-scan image stack into distinctive phases. Then, we conduct numerical simulations of electric potential distribution in conjunction with streamline tracing techniques to quantify the electrical tortuosity of the continuous phase in each cartesian direction. We employed the tortuosity distribution values in each direction as a measure of rock anisotropy. Finally, we use a simulation model to estimate direction-dependent elastic properties. We applied the introduced method to dual energy whole-core CT-scan image stacks acquired in a siliciclastic depth interval. Estimates of rock anisotropy obtained using the proposed method agreed with the observed visual distribution of the segmented phase and the observed heterogeneity in available slabbed whole-core photos and 2D CT-scan images. Additionally, estimation of directional-dependent elastic properties demonstrated the value of the proposed method. Anisotropy results coincided with directional-dependent estimation of elastic properties. We observed measurable anisotropy in the 3D CT-scan image stacks, which is important to be quantitatively taken into account in petrophysical/ mechanical evaluation of this formation. A unique contribution of the proposed workflow is the use of core-scale image data for anisotropy estimation and the continuous nature of the anisotropy estimates when compared with workflows employing only pore-scale image data. It should also be noted that the proposed method can potentially be employed to identify the optimum locations to acquire core plugs for further assessment of rock anisotropy.
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Gonzalez, Andres, Zoya Heidari, and Olivier Lopez. "Electrical, Diffusional, and Hydraulic Tortuosity Anisotropy Quantification Using 3D CT-Scan Image Data." In SPE Annual Technical Conference and Exhibition. SPE, 2021. http://dx.doi.org/10.2118/206109-ms.
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Abstract Depositional mechanisms of sediments and post-depositional process often cause spatial variation and heterogeneity in rock fabric, which can impact the directional dependency of petrophysical, electrical, and mechanical properties. Quantification of the directional dependency of the aforementioned properties is fundamental for the appropriate characterization of hydrocarbon-bearing reservoirs. Anisotropy quantification can be accomplished through numerical simulations of physical phenomena such as fluid flow, gas diffusion, and electric current conduction in porous media using multi-scale image data. Typically, the outcome of these simulations is a transport property (e.g., permeability). However, it is also possible to quantify the tortuosity of the media used as simulation domain, which is a fundamental descriptor of the microstructure of the rock. The objectives of this paper are (a) to quantify tortuosity anisotropy of porous media using multi-scale image data (i.e., whole-core CT-scan and micro-CT-scan image stacks) through simulation of electrical potential distribution, diffusion, and fluid flow, and (b) to compare electrical, diffusional, and hydraulic tortuosity. First, we pre-process the images (i.e., CT-scan images) to remove non-rock material visual elements (e.g., core barrel). Then, we perform image analysis to identify different phases in the raw images. Then, we proceed with the numerical simulations of electric potential distribution. The simulation results are utilized as inputs for a streamline algorithm and subsequent direction-dependent electrical tortuosity estimation. Next, we conduct numerical simulation of diffusion using a random walk algorithm. The distance covered by each walker in each cartesian direction is used to compute the direction-dependent diffusional tortuosity. Finally, we conduct fluid-flow simulations to obtain the velocity distribution and compute the direction-dependent hydraulic tortuosity. The simulations are conducted in the most continuous phase of the segmented whole-core CT-scan image stacks and in the segmented pore-space of the micro-CT-scan image stacks. Finally, the direction-dependent tortuosity values obtained with each technique are employed to assess the anisotropy of the evaluated samples. We tested the introduced workflow on dual energy whole-core CT-scan images and on smaller scale micro-CT-scan images. The whole-core CT-scan images were obtained from a siliciclastic depth interval, composed mainly by spiculites. Micro-CT-scan images we obtained from Berea Sandstone and Austin Chalk formations. We observed numerical differences in the estimates of direction-dependent electrical, diffusional, and hydraulic tortuosity for both types of image data employed. The highest numerical differences were observed when comparing electrical and hydraulic tortuosity with diffusional tortuosity. The observed differences were significant specially in anisotropic samples. The documented comparison provides useful insight in the selection process of techniques for estimation of tortuosity. The use of core-scale image data in the proposed workflow provides semi-continuous estimates of tortuosity and tortuosity anisotropy which is typically not attainable when using pore-scale images. Additionally, the semi-continuous nature of the tortuosity and tortuosity anisotropy estimates in whole-core CT-scan image data provides an excellent tool for the selection of core plugs coring locations.
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Sonkova, Pavlina, Iordanis E. Evangelou, Antonio Gallo, Fredric K. Cantor, Joan Ohayon, Henry F. McFarland, and Francesca Bagnato. "Semi-automatic segmentation and modeling of the cervical spinal cord for volume quantification in multiple sclerosis patients from magnetic resonance images." In Medical Imaging, edited by Joseph M. Reinhardt and Josien P. W. Pluim. SPIE, 2008. http://dx.doi.org/10.1117/12.773055.
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Machado, Fernanda Almeida, Paula Pontes Mota, Lorena Claudia de Souza Moreira, and Regina Coeli Ruschel. "Template class to teach clash detection." In ENCONTRO NACIONAL SOBRE O ENSINO DE BIM. Antac, 2021. http://dx.doi.org/10.46421/enebim.v3i00.315.
Full textAbstract:
BIM uses are complex specific processes in architecture, engineering, construction, and operation mediated by Building Information Modeling technologies. Several initiatives are dedicated to detailing these uses in a standardized way, enumerating and describing them in terms of scope, benefits, process maps, required competencies, associated technology, and theoretical framework. Examples of these efforts are Penn State's Computer Integrated Construction Research Program (MESSNER et al., 2019), buildingSMART (2021), and BIM Excellence Organization (SUCCAR; SALEEB; SHER, 2016). This study presents the approach to educate, evaluate and assist Model Uses using templates (Model Use Templates - MUT) of the BIM Excellence Initiative (BIMe). The BIM use is called Model Use in BIMe terminology. In three years, starting in 2021, the initiative intends to detail all the domain model uses listed by the organization (BIMe, 2020). The domain model uses are organized in the series of capture and representation, planning and design, simulation and quantification, operation and maintenance, monitoring and control of buildings and infrastructures. In terms of domain model uses, there is the linking and extending series of BIM integrated to Facility Management, interfaced with the Internet of Things, linked to Enterprise Resource Planning, etc. The initiative developed a Construction Domain Model Use Template (MUT) and applied it as a demonstration for Clash Detection or MUT 4040. This summary will describe the template, its application to Clash Detection, and guidance on how to transform it into a template class to teach Clash Detection with BIM. The MUT consists of an extended description, software list, activity flow, and bibliography. This content is available in the BIM Dictionary associated with the equivalent term (https://bimdictionary.com/en/clash-detection/1). The extended description includes the corresponding term's definition, the detailed description, purpose, and an available online media-list. The detailed description presents the different types of use (e.g., hard, soft, time-based) and benefits. The software list lists platforms and environments used in the model use development. For each platform or environment, there is a list of the vendor or developer, the corresponding technical functionality, the applicable discipline, the software description, the availability of the software in the cloud or location, differentiation of versions, the link to the official website, the model use code that the software can support, specific functionalities associated with the use and availability of a plugin or extension. The activity flow is described using a process map and details in up to 3 hierarchical levels for each macro activity. All the terminology adopted in the MUT is semantically aligned to the various projects and initiatives of BIM Excellence, bringing consistency to the meaning. In the case of MUT 4040, that is, the application of the template for the model use of Clash Detection, the short description is a “Use of the Model representing the use of 3D Models to coordinate different disciplines (e.g., structures and air-conditioning) and to identify/resolve possible conflicts between virtual elements prior to actual construction or fabrication”. The extended description presents the Clash Detection as automated or semi-automated procedures to identify design errors in 3D models, where objects occupy the same space or are too close to violating spatial restrictions. Time-based interferences are conflicts involving temporary objects that compete for the same space at the same time. The benefits are listed, for example, like better project coordination and quality; conflict reduction in the workplace; acceleration of design and delivery processes; and cost reduction through productivity increase. The available online media does not represent the entire process involved in Clash Detection and are generally restricted to confronting models on specific platforms. We advocate that the activity flow should structure the class of model uses in BIM education. In this way, there is a holistic and representative approach to practice. Thus, we advise escaping this model's understanding in a restricted and instrumental way, as it already occurs in most of the online media found. We propose to organize the class program by the macro stages of the activity flow, covering: (i) creation of the strategy for the clash detection in the project in question; (ii) preparation of specific models for federation; (iii) identification of federation environments or model integration; (iv) federation or integration of models; (v) checks for interference in the federated or integrated model; (vi) analysis of the conflicts identified; and (vii) referral to conflict resolution. The details of each of these activities in the template can guide the teacher on how to proceed or prepare educational content. The bibliography listed in the template covers the theoretical framework to support the class in terms of books, scientific articles, and BIM guides. One can develop the class at the level of graduation, extension, or continuing education. Being an undergraduate class, it can be mandatory or elective. Items (i) to (iii) make up the theoretical part of the class, and the rest are essentially practical content. Thus, two types of competency assessment are possible: knowledge and skills. Knowledge can be developed through discussions and seminars. Skills covered are associated with execution or domain skills, according to Succar, Scher, and Willams (2013). Execution skills are associated with learning model verification platforms and collaboration environments. The execution competence generates an instrumental skill that can be provided through individual online training with tutorials. Domain skills are essentially technical (analysis and simulation) and functional (collaboration). These skills must be instigated in a participatory and collaborative way in practical exercises involving cycles of verification of the federated model and adjustments of complementary projects' models. As a suggestion for support material, the teacher should prepare a dataset including models with errors in file naming disobeying conventions, errors in the control elements impacting the overlapping of models, errors of omission or duplication of elements in the models, and errors of data schema in terms of categorization of elements and classification of content. The models must also include issues of all types (hard, soft, and temporal interferences). Errors must be plausible to be identified by different types of verification: visual or script. YouTube presentation: https://youtu.be/cMPaw_kOZtQ