Author: RODRÍGUEZ GONZÁLEZ, MARÍA DOLORES
Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
Programme: DOCTORAL DEGREE IN NUCLEAR AND IONISING RADIATION ENGINEERING
Department: Institute of Energy Technologies (INTE)
Mode: Normal
Deposit date: 28/09/2020
Reading date: 26/10/2020
Reading time: 12:00
Reading place: Aula 31.07 Pavelló C - ETSEIB - Campus Sud - Avinguda Diagonal, 647, 08028 Barcelona - Videoconferència: https://meet.google.com/zki-nbju-hfn
Thesis director: VARGAS DRECHSLER, ARTURO
Committee:
     PRESIDENT: FONT GUITERAS, LLUÍS
     SECRETARI: DUCH GUILLEN, MARIA AMOR
     VOCAL: GARCÍA-TALAVERA SAN MIGUEL, MARTA
Thesis abstract: Compton cameras are used for radiological imaging, which can be useful in environmental applications and especially in determining the position of hidden sources. Current Compton cameras are based on pixelated detectors with complex electronic instrumentation and these devices are usually expensive. In order to overcome these issues, a Compton camera consisting of scintillator bars with two photo-sensors placed at both ends is a promising option. In addition, it is expected that these kind of detectors make the Compton camera lightweight and robust.Characterization of two identical CsI(Tl) scintillator bars with two silicon photomultipliers each was done. The basic characterization parameters of detectors, such as the attenuation coefficient, position resolution and energy resolution, were determined experimentally with a collimated Cesio-137 point source. Different light attenuation coefficients were found for identical scintillators, causing different position resolutions. This fact highlights the importance of carrying out a control analysis for each detector. In addition, the position resolution and energy resolution were found to be independent of the position of ¿-ray interactions within the crystal. Monte Carlo (MC) simulations with PENELOPE/penEasy were carried out to design a Compton camera. In order to achieve this, the MC simulations needed to be validated. This was done by comparing both simulated and experimental data obtained in two different experimental measurement campaigns. In the first campaign, two detectors were irradiated individually with a collimated point source, while the second campaign consisted of irradiating a simple Compton camera made of two CsI(Tl) scintillator bars. The geometry defined in the MC simulations and the codes used to calculate the image for a Compton camera based on CsI(Tl) scintillator bars were validated with these experimental campaigns. The response of each individual detector, the Compton camera efficiency, the angular resolution and images obtained with MC simulations and experimental measurements were compared. Results show good agreement between experimental and simulated data.Once the MC simulations were fully validated, the design of a Compton camera consisting of two layers with four CsI(Tl) scintillator bars each was done. The cross-section size of crystals and distance between layers were optimized based on Compton camera efficiency, angular resolution and image resolution. This analysis was carried out with an energy range of 360-1330 keV. The final optimized Compton camera consists of two layers separated by 10 cm. Each layer has four 2×2×10 cm3 CsI(Tl) scintillator bars. The characterization of the Compton camera was then carried out. The field of view, efficiency, angular resolution and image resolution were calculated. In addition, the ability of the Compton camera to make use of the simple back-projection method to identify radioactive material in the environment has also been evaluated by simulating several point sources. The Compton camera was able to detect several point sources simultaneously, however, as the number of sources increases, the images became blurred. The capacity of the Compton camera is promising, since it can detect several sources in the environment according to MC simulations. Therefore, the construction of a Compton camera based on eight 2×2×10 cm3 CsI(Tl) scintillator bars should prove to be useful for environmental measurements and for installation on unmanned aerial systems, commonly called ¿drones¿.

Author: CASANOVAS HOSTE, ADRIA
Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
Programme: DOCTORAL DEGREE IN NUCLEAR AND IONISING RADIATION ENGINEERING
Department: Institute of Energy Technologies (INTE)
Mode: Normal
Deposit date: 04/09/2020
Reading date: 27/10/2020
Reading time: 10:00
Reading place: Aula 31.07 del pavelló C de l'ETSEIB. Videoconferència https://meet.google.com/ken-pmnp-quo
Thesis director: DOMINGO PARDO, CÉSAR | CALVIÑO TAVARES, FRANCISCO
Committee:
     PRESIDENT: PRETEL SANCHEZ, MARIA DEL CARMEN
     SECRETARI: LEDERER-WOODS, CLAUDIA
     VOCAL: MENGONI, ALBERTO
Thesis abstract: Neutron capture cross sections are fundamental in the study of the slow neutron capture process of nucleosynthesis, also known as the s-process, which produces half of the observed solar system abundances of elements heavier than iron.Some nuclei along the nucleosynthesis chain are unstable, and there the capture process competes with the decay process, creating a split in the nucleosynthesis path. The nuclear properties of some of these radionuclides change with the conditions of the stellar environment, a fact that influences the local abundance pattern. 204Tl is a very interesting branching point, because it is shielded from any contribution from other nucleosynthesis processes. The result is that both 204Tl and its stable daughter isotope 204Pb are only produced by the s-process. Hence, by competing with the beta decay, the capture cross section of 204Tl crucially determines the final abundance of 204Pb. A faithful prediction of the solar abundances of s-only isotopes, like 204Pb, is one of the key accuracy tests for modern stellar nucleosynthesis calculations.However, until the present work, due to the challenges of performing a capture measurement on 204Tl, there was no experimental data of its cross section. Thus, large uncertainties existed in its capture cross section, which hampered a more accurate and precise knowledge of the predicted s-process production of 204Pb.By affecting the abundance of 204Pb, the cross section of 204Tl(n,¿) also influences the ratio of abundances 205Pb/204Pb. 205Pb is also produced only by the s-process, and it is radioactive, with a long half-life of 17.2 My. Therefore, the ratio of abundances of 205Pb/204Pb has the potential to be used as a chronometer of the s-process.In the year 2013, a sample enriched up to a few percent in 204Tl was produced by neutron irradiation of a 203Tl seed sample at the high thermal neutron flux nuclear reactor of the ILL, in Grenoble (France). Two years later, the 204Tl enriched sample was employed to measure, for the first time, the capture cross section of 204Tl at the n TOF time-of-flight facility at CERN. The measurement was possible thanks to the unique features of this facility, in particular, its high instant neutron flux low background levels. The measurement was performed employing the well-established total energy detection technique (TED), which offers a very low neutron sensibility, and low levels of background, compared to other methods like the Total Absorption technique.The main challenges for the 204Tl measurement were the very high background due to the activity of the sample, the very low amount of material, and the limited knowledge of the geometry of the sample. Such difficulties required the adoption of specific solutions during the measurement and the posterior data analysis. Related to this, several sources of systematic error were evaluated by means of Monte Carlo simulations.The complications with the 204Tl sample geometry required to apply an in-sample normalization procedure. For this purpose, an ancillary capture measurement on a 203Tl sample was also performed in the same experimental campaign. As a stable nuclide, most of the sources of systematic error could be kept under control. This allowed for an accurate R-matrix analysis of the most relevant capture levels in the resolved resonance region of 203Tl, including the first ever measurement under 3 keV of neutron energy. As a result, the present work has contributed, as well, to improve the 203Tl stellar capture cross section in the 8 to 25 keV neutron energy range.With the improved 203Tl(n,¿) cross section, an R-matrix analysis of several 204Tl resonances was made possible. These results were employed to experimentally constrain the 204Tl stellar cross section at low energies, and setting additional limits to the stellar cross section predicted by nuclear data evaluations at s-process temperatures.

Author: GHRAB, AMINE
Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
Programme: ERASMUS MUNDUS DOCTORAL DEGREE IN INFORMATION TECHNOLOGIES FOR BUSINESS INTELLIGENCE
Department: Department of Service and Information System Engineering (ESSI)
Mode: Change of supervisor
Deposit date: 21/09/2020
Reading date: 29/10/2020
Reading time: 09:00
Reading place: Université Libre de Bruxelles (ULB) -Videoconferència (https://tinyurl.com/y7m66oat)
Thesis director: ROMERO MORAL, OSCAR | ZIMANYI BORRAGEIROS, ESTEBAN
Committee:
     PRESIDENT: VANSUMMEREN, STIJN
     SECRETARI: VOIGT, HANNES
     VOCAL NO PRESENCIAL: BUGIOTTI, FRANCESCA
Thesis abstract: Over the last decade, we have witnessed the emergence of networks in a wide spectrum of application domains, ranging from social and information networks to biological and transportation networks.Graphs provide a solid theoretical foundation for modeling complex networks, and revealing valuable insights from both the network structure and the data embedded within its entities.As the business and social environments are getting increasingly complex and interconnected, graphs became a widespread abstraction at the core of the information infrastructure supporting those environments. Modern information systems consist of a large number of sophisticated and interacting business entities that naturally form graphs. In particular, integrating graphs into data warehouse systems received a lot of interest from both academia and industry. Indeed, data warehouses are the central enterprise's information repository, and are critical for proper decision support and future planning. Graph warehousing is emerging as the field that extends current information systems with graph management and analytics capabilities. Many approaches were proposed to address the graph data warehousing challenge. These efforts laid the foundation for multidimensional modeling and analysis of graphs. However, most of the proposed approaches partially tackle the graph warehousing problem by being restricted to simple abstractions such as homogeneous graphs or ignoring important topics such as multidimensional integrity constraints and dimension hierarchies.In this dissertation, we conduct a systematic study of the graph data warehousing topic, and address the key challenges of database and multidimensional modeling of graphs.We first propose GRAD, a new graph database model specifically tuned for warehousing and OLAP analytics. GRAD aims to provide analysts with a set of simple, well-defined, and adaptable conceptual components to support rich semantics and perform complex analysis on graphs.Then, we define the multidimensional concepts for heterogeneous attributed graphs and highlight the new types of measures that could be derived. We project this multidimensional model on property graphs and explore how to extract the candidate multidimensional concepts and build graph cubes. Then, we extend the multidimensional model by integrating GRAD and show how graph modeling based on GRAD facilitates multidimensional modeling, and enables supporting dimension hierarchies and building new types of OLAP cubes on graphs.Afterwards, we present TopoGraph, a graph data warehousing framework that extends current graph warehousing models with new types of cubes and queries combining graph-oriented and OLAP querying. TopoGraph goes beyond traditional OLAP cubes, which process value-based grouping of tables, by considering in addition the topological properties of the graph elements. And it goes beyond current graph warehousing models by proposing new types of graph cubes. These cubes embed a rich repertoire of measures that could be represented with numerical values, with entire graphs, or as a combination of them.Finally, we propose an architecture of the graph data warehouse and describe its main building blocks and the remaining gaps. The various components of the graph warehousing framework can be effectively leveraged as a foundation for designing and building industry-grade graph data warehouses.We believe that our research in this thesis brings us a step closer towards a better understanding of graph warehousing. Yet, the models and framework we proposed are the tip of the iceberg. The marriage of graph and warehousing technologies will bring many exciting research opportunities, which we briefly discuss at the end of the thesis.

Author: ORDOÑO FERNÁNDEZ, JESÚS
Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
Programme: DOCTORAL DEGREE IN BIOMEDICAL ENGINEERING
Department: (CEM)
Mode: Temporary seizure
Deposit date: 29/09/2020
Reading date: pending
Reading time: pending
Reading place: pending
Thesis director: ENGEL LOPEZ, ELISABET | PEREZ AMODIO, SOLEDAD GRACIELA
Committee:
     PRESIDENT: SEMINO MARGRETT, CARLOS EDUARDO
     SECRETARI: CANAL BARNILS, CRISTINA
     VOCAL: MORONI, LORENZO
Thesis abstract: The increasing prevalence of cardiovascular diseases and their high health and socioeconomic impact on the world population urge the development of efficient new therapies for the reestablishment of the cardiac function. The heart has a very limited regenerative ability, and so lost cardiomyocytes cannot be replaced, thus causing permanent damage. These cells undergo different metabolic changes during development crucial for their maturation and adult function. During fetal development, proliferating cardiac cells reside in a low oxygen environment with high concentrations of lactate. After birth, cardiomyocytes cease their proliferating activity and shift their metabolism to fatty acid oxidation. Alterations of cardiac metabolism have also been associated with multiple disease states and pathological hypertrophy. Here in this work, we evaluated the response of cardiac cells to the presence of exogenous lactate, thus mimicking the metabolic microenvironment of early developmental stages.Lactate-exposed mouse primary cardiomyocytes and human iPSC-derived cardiomyocytes quickly acquired a characteristic dedifferentiated phenotype, with enhanced proliferative activity as determined by the expression of cell cycle (Ki67) and cytokinesis (AurB) effectors. We characterized lactate-induced cardiomyocyte dedifferentiation through RNA-sequencing and gene expression analysis and identified increased expression of BMP10 (involved in embryonic cardiomyocyte proliferation and stemness), LIN28 (a master regulator of stem cell fate and metabolism) and other genes associated to regulation of the stem cell fate (P63, TCIM or GATA4). On the other hand, we saw a downregulation of cardiac maturation genes related to lipid metabolism (DGKK) or electrical impulse regulation (GRIK1). Bottom-up analysis suggested the activation of hypoxia signaling pathways, indicating that, indeed, lactate may be a key player of hypoxic regenerative responses in the heart.Cardiomyocytes, however, are only 30-40% of the total population of cardiac cells. The majority of non-myocyte cells are comprised of cardiac fibroblasts and endothelial cells, whose interactions with cardiomyocytes highly contribute to heart repair and tissue homeostasis. Our results showed that lactate did not affect cardiac fibroblast proliferation, collagen production, migration or myofibroblast activation, which are detrimental factors for an effective cardiac regeneration. Lactate showed to reduce the expression of inflammatory cytokines involved in heart failure and cardiomyocyte apoptosis (Fas, Fractalkine or IL-12p40) and promote the production of healing and pro-regenerative signals (IL-13 and SDF-1a). In addition, endothelial precursor cells demonstrated their ability to use lactate as an effective energy source for survival and proliferation, even equivalent to the utilization of glucose. Taken together, the synergistic lactate response of the main cardiac cell types could enhance heart regeneration by supporting the growth and survival of new cardiomyocytes to repopulate the ischemic injury.Additionally, cardiac tissue constructs and ex vivo neonatal heart culture showed a more immature electromechanical behavior, with prolonged cardiac functions and improved proliferation as well as tissue integrity when culture media was supplemented with lactate. Thus, we explored the use of lactate-releasing cardiac scaffolds using different biomaterials, such as PLA, PLGA, alginate or conductive polymers, and different fabrication techniques, such as electrospinning; considering the fundamental aspects of cardiac scaffolds (anisotropy, flexibility and conductivity). These scaffolds proved to be an attractive and simple approach for a cardiac regenerative therapy.Altogether, the use of lactate as a metabolic modulator for the in situ activation of endogenous cardiac regenerative programs may revolutionize the design of new therapies for the treatment and regeneration of the failing heart.

Author: RIVERA ROGEL, CARMEN ALICIA
Thesis file: (contact the Doctoral School to confirm you have a valid doctoral degree and to get the link to the thesis)
Programme: DOCTORAL DEGREE IN ARCHITECTURAL, BUILDING CONSTRUCTION AND URBANISM TECHNOLOGY
Department: Department of Architectural Technology (TA)
Mode: Temporary seizure
Deposit date: 15/09/2020
Reading date: 29/10/2020
Reading time: 11:00
Reading place: Sala de Graus ETSAB - UPC Campus Sud - Av Diagonal 649 - videoconferència: meet.google.com/zcm-gbbc-wec
Thesis director: ALBAREDA VALLS, ALBERT
Committee:
     PRESIDENT: GARCÍA CARRERA, DAVID
     SECRETARI: PÉREZ VALCÁRCEL, JUAN BAUTISTA
     VOCAL NO PRESENCIAL: RETAMALES SAAVEDRA, RODRIGO ALFONSO
Thesis abstract: Hospitals are a fundamental part of a country's health system and are considered essential facilities for dealing with natural disasters. Nevertheless, hospitals may be highly vulnerable structures. Loss of functionality, even for a short period of time, may be critical for people inside the hospital, as well as for those who may need urgent medical attention following a natural disaster. Despite the importance of these buildings, many hospitals have resulted severely damaged, and some have lost functionality after moderate earthquakes. Recent seismic events, such as the 2016 Ecuador Mw 7.8 earthquake, highlighted the role of nonstructural components and systems after a seismic event. The damage observed showed that the loss of functionality of most hospital buildings was mostly related to damage of ceilings, partitions, water supply systems, and overturning of mechanical and medical equipment, among others. However, only a few studies have addressed the consequences of nonstructural damage in the functionality loss of health facilities.In this study, a methodology for rapid visual assessment of susceptibility of functional loss due to earthquakes in health infrastructure by using an automated tool is presented. In particular, the tool allows estimating the operational vulnerability of the infrastructure following strong ground motions. The nonstructural elements are classified according to FEMA and World Health Organization procedures as architectural components (exterior and interior), building utility systems (equipment and distributed systems of critical support services), medical equipment (medical services and medical gases), and contents (cabinets, furniture, fixtures, and similar). Potential physical losses caused by story drifts and floor accelerations are considered. The prediction of damage is determined by using fragility curves taken mainly from the FEMA P-58 database, HAZUS, test reports and analytical methods. The tool is calibrated using damage observed during recent earthquakes affecting 17 case studies. The seismic actions that generated these damages are estimated from accelerograms recorded by the closest seismological stations. The calibration is based on comparing the observed damage with the predicted one, obtained from combining the fragility curves with the estimated actual seismic demands.This automated tool for rapid assessment of susceptibility of functional loss due to earthquakes is expected to contribute to a better understanding of the seismic performance of nonstructural components and systems in health infrastructure. This work will be useful for hospital managers and staff, as well as decision-makers in the health ministries of a country, in order to anticipate the functional loss expected in health infrastructure or in a health care network within an administrative area local, or at regional or country-level. Consequently, the presented tool can be used to determine the actions and measures that are required in order to improve safety and achieve continuous operation of health facilities during and after seismic events.