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14 results on '"Gutierrez, J E"'

2. Towards Reliable Performance Predictions for Stommel's Perpetual Salt Fountain

Author

Garcia-Espinosa, J., Gonzalez, L., Gutierrez, J. E., Servan-Camas, B., Kemper, Jost, Mense, Jan, Graf, Kai, Kröger, Jörn, Riebesell, Ulf, Garcia-Espinosa, J., Gonzalez, L., Gutierrez, J. E., Servan-Camas, B., Kemper, Jost, Mense, Jan, Graf, Kai, Kröger, Jörn, and Riebesell, Ulf

Abstract

Artificial Upwelling (AU) of nutrient-rich Deep Ocean Water (DOW) to the ocean’s sunlit surface layer is currently being investigated as a way of increasing the ecosystem productivity and enhancing the natural CO2 uptake of the ocean. AU is thus considered a marine Carbon Dioxide Removal (CDR) option (GESAMP, 2019) in addition to its potential in the context of open ocean fish and macroalgae farming (Kirke, 2003; Wu et al., 2023). A promising technical concept for AU was described by the oceanographer Stommel et al. (1956). Stommel proposed that the counteracting effects of typical open ocean temperature and salinity depth profiles on density can be utilized to drive a self-sustaining upwelling flow in a vertical ocean pipe. He termed this effect the ”perpetual salt fountain”. Despite several research efforts, none of the previous studies were able to reliably predict or demonstrate the potential of Stommel Upwelling Pipes (SUP)s. The growing interest in AU in light of current CDR research poses the need for reliable performance prediction methods and further development of Stommel’s concept. To fill this gap, two models have been developed in the present work. A Reynolds-Averaged Navier-Stokes (RANS) model and a one-dimensional numerical model. While the RANS model enables detailed modeling of the heat transfer and flow phenomena, the one-dimensional numerical model allows for fast evaluation of simplified geometries for optimization and large-scale studies. This twofold approach allows for effective performance predictions while ensuring good reliability of the results. The present work shows the results of a number of studies, performed for different geometries and environmental conditions. The results of both models are compared and analyzed, and the respective potential is demonstrated. The presented results provide insight into some key aspects of the performance of SUPs and their potential for AU.

Published
2023
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3. C455R notch3 mutation in a Colombian CADASIL kindred with early onset of stroke

Author

Arboleda–Velasquez, J. F., primary, Lopera, F., additional, Lopez, E., additional, Frosch, M. P., additional, Sepulveda–Falla, D., additional, Gutierrez, J. E., additional, Vargas, S., additional, Medina, M., additional, Martinez de Arrieta, C., additional, Lebo, R. V., additional, Slaugenhaupt, S. A., additional, Betensky, R. A., additional, Villegas, A., additional, Arcos–Burgos, M., additional, Rivera, D., additional, Restrepo, J. C., additional, and Kosik, K. S., additional

Published
2002
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5. C455R notch3mutation in a Colombian CADASIL kindred with early onset of stroke

Author

Arboleda–Velasquez, J. F., Lopera, F., Lopez, E., Frosch, M. P., Sepulveda–Falla, D., Gutierrez, J. E., Vargas, S., Medina, M., Martinez de Arrieta, C., Lebo, R. V., Slaugenhaupt, S. A., Betensky, R. A., Villegas, A., Arcos–Burgos, M., Rivera, D., Restrepo, J. C., and Kosik, K. S.

Abstract

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is caused by mutations in the notch3epidermal growth factor–like repeats. A Colombian kindred carries a novel C455R mutation located in the predicted ligand-binding domain. Stroke occurred in the patients at an unusually early age (median age 31 years) in comparison to the more frequent onset in the fourth decade of life in other CADASIL populations, including a second Colombian kindred with an R1031C mutation.

Published
2002

6. Dynamic modelling of mooring for floating offshore structuresmarine 2013

Author

Gutierrez, J. E., Zamora, B., Julio García-Espinosa, Esteve, J., Universitat Politècnica de Catalunya. Departament de Ciència i Enginyeria Nàutiques, and Universitat Politècnica de Catalunya. TRANSMAR - Grup de recerca de transport marítim i logística portuària

Subjects
Offshore structures, Coupled analysis, Lumped mass, Nàutica::Enginyeria naval [Àrees temàtiques de la UPC], Estructures marines, Enginyeria civil::Enginyeria hidràulica, marítima i sanitària [Àrees temàtiques de la UPC], Amarratge de vaixells, Nàutica::Infraestructures portuàries [Àrees temàtiques de la UPC], Maneuvering boards, Mooring dynamics
Abstract

There is a demandto develop and evaluate new concepts for offshore structures for harnessing ocean energy. Tools capableof calculatingthe behaviour of this kind of structures are also requestedby the industry. An accurate analysis comprises fully coupled simulations and the use of complex models for non-linear dynamics analysis, including the modellingofmooring lines onfloating offshore structures. In opposite of quasi-staticmodellingof mooring lines such as catenary lines [1],time-dependent models [2, 3] present some advantages.This workpresents a dynamic modelof mooring lines for deep-water structures using LMM (Lumped Mass Method)[4, 5] formulation and its application on differentkinds of floating devices. First, the mathematical model for mooring lines is presented. Then anapplication tool based on that mathematical model is showed. This tool is linked to the time-domain seakeeping solver SeaFEM [6]. The resulting model is able to obtain a fully coupled analysis of seakeeping and mooring dynamics of floating offshore structures. A preliminary study of mooring dynamics is presented over differentsolutions and configurations of mooring lines for severalfloating devices. Furthermore, an optimal design of mooring line configurations for differentsolutions of floating structures can be achieved.This work also presents the study of differentfloating devices under several sea wave conditions. Finallysome conclusions are remarked, and the future research lines are presented.

9. Increased differentiation of intracranial white matter lesions by multispectral 3D-tissue segmentation: preliminary results.

Author

Mohamed FB, Vinitski S, Gonzalez CF, Faro SH, Lublin FA, Knobler R, and Gutierrez JE

Subjects
Adult, Aged, Atrophy, Brain pathology, Diagnosis, Differential, Female, Humans, Male, Middle Aged, Sensitivity and Specificity, Cerebral Infarction diagnosis, Dementia, Vascular diagnosis, Image Enhancement, Image Processing, Computer-Assisted, Imaging, Three-Dimensional, Magnetic Resonance Imaging, Multiple Sclerosis diagnosis
Abstract

MRI is a very sensitive imaging modality, however with relatively low specificity. The aim of this work was to determine the potential of image post-processing using 3D-tissue segmentation technique for identification and quantitative characterization of intracranial lesions primarily in the white matter. Forty subjects participated in this study: 28 patients with brain multiple sclerosis (MS), 6 patients with subcortical ischemic vascular dementia (SIVD), and 6 patients with lacunar white matter infarcts (LI). In routine MR imaging these pathologies may be almost indistinguishable. The 3D-tissue segmentation technique used in this study was based on three input MR images (T(1), T(2)-weighted, and proton density). A modified k-Nearest-Neighbor (k-NN) algorithm optimized for maximum computation speed and high quality segmentation was utilized. In MS lesions, two very distinct subsets were classified using this procedure. Based on the results of segmentation one subset probably represent gliosis, and the other edema and demyelination. In SIVD, the segmented images demonstrated homogeneity, which differentiates SIVD from the heterogeneity observed in MS. This homogeneity was in agreement with the general histological findings. The LI changes pathophysiologically from subacute to chronic. The segmented images closely correlated with these changes, showing a central area of necrosis with cyst formation surrounded by an area that appears like reactive gliosis. In the chronic state, the cyst intensity was similar to that of CSF, while in the subacute stage, the peripheral rim was more prominent. Regional brain lesion load were also obtained on one MS patient to demonstrate the potential use of this technique for lesion load measurements. The majority of lesions were identified in the parietal and occipital lobes. The follow-up study showed qualitatively and quantitatively that the calculated MS load increase was associated with brain atrophy represented by an increase in CSF volume as well as decrease in "normal" brain tissue volumes. Importantly, these results were consistent with the patient's clinical evolution of the disease after a six-month period. In conclusion, these results show there is a potential application for a 3D tissue segmentation technique to characterize white matter lesions with similar intensities on T(2)-weighted MR images. The proposed methodology warrants further clinical investigation and evaluation in a large patient population.

Published
2001
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11. Salvage of the ischemic limb. Hemodynamic changes during surgery.

Author

Bernhard VM, Kayser K, Gutierrez JE, Wilson SD, Rodgers RE, and Ellison EH

Subjects
Adult, Aged, Amputation, Surgical, Aorta, Abdominal surgery, Blood Flow Velocity, Blood Pressure, Blood Vessel Prosthesis, Female, Femoral Artery surgery, Femoral Vein surgery, Hemodynamics, Humans, Iliac Artery surgery, Ischemia diagnostic imaging, Leg blood supply, Leg diagnostic imaging, Male, Middle Aged, Papaverine therapeutic use, Polymers, Popliteal Artery surgery, Popliteal Vein surgery, Radiography, Skin Ulcer etiology, Transplantation, Autologous, Vascular Resistance, Veins transplantation, Ischemia surgery, Leg surgery
Published
1968

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