Partes de Libroshttp://hdl.handle.net/11086/169892024-03-28T23:22:58Z2024-03-28T23:22:58ZIdentificación de partículas incluidas en hielos naturales (glaciares, permafrost, granizo) por sublimación adaptadaArena, Lucía Elizabethhttp://hdl.handle.net/11086/5492502023-10-03T12:28:08Z2023-07-26T00:00:00ZIdentificación de partículas incluidas en hielos naturales (glaciares, permafrost, granizo) por sublimación adaptada
Arena, Lucía Elizabeth
Las partículas atrapadas en los hielos naturales (glaciares, permafrost, granizos, etc.) dan información valiosa sobre los ambientes en los que se formaron. En los testigos antárticos, las partículas aportan datos que favorecen las reconstrucciones paleoclimáticas y en los granizos hay partículas atmosféricas que desempeñan un papel crucial en la microfísica de nubes, en la nucleación de gotas y cristales de nieve, y están relacionadas con los vientos que intervienen en la tormenta. La extracción de las partículas habitualmente se realiza a través de la fusión del hielo y el filtrado posterior del agua obtenida, lo que requiere de una sala limpia de trabajo. Aquí se presenta una metodología novedosa de extracción de partículas del hielo desde la fase sólida, que resulta eficiente, de bajo costo en infraestructura y que minimiza las posibles fuentes de contaminación. La metodología, que llamamos de separación de partículas por sublimación adaptada, permite determinar la distribución espacial y la concentración de partículas, así como sus tamaños (sin las limitaciones de las filtraciones), la forma, estructura y composición química elemental de las mismas. El método se aplica a un granizo que cayó en Villa Carlos Paz de Córdoba, Argentina en la tormenta del 8 de febrero de 2018, el cual fue recolectado en el marco del programa COSECHEROS, el cual tiene en su centro una partícula de tamaño mediano de 40 um.; Particles trapped in natural ice (glaciers, permafrost, hail, etc.) provide valuable information about the environments in which they formed. In the Antarctic cores, the particles provide data that favors paleoclimatic reconstructions and in the hailstones there are atmospheric particles that play a crucial role in the microphysics of clouds, in the nucleation of snow, drops and crystals, and are related to the winds that intervene in the storm. The extraction of the particles is usually carried out by melting the ice and subsequent filtering of the water obtained, which requires a clean work room. Here, a novel methodology for extracting
ice particles from the solid phase is presented, which is efficient, low-cost in infrastructure, and minimizes possible sources of contamination. The methodology, which we call particle separation by adapted sublimation, allows us to determine the spatial distribution and concentration of particles, as well as their sizes (without the limitations of filtration), their shape, structure and elemental chemical composition. The method is applied to a hail that fell in Villa Carlos Paz de Córdoba, Argentina in the storm of February 8, 2018, which was collected within the framework of the COSECHEROS program, which has in its center a
medium-sized particle of 40 um.
2023-07-26T00:00:00Z1H NMR Spectroscopy and MR Imaging with hyperpolarised substancesGraafen, DirkNeudert, OliverBuljubasich Gentiletti, LisandroFranzoni, María BelénDechent, Jan FalkMünnemann, Kerstinhttp://hdl.handle.net/11086/263092023-08-31T13:17:10Z2014-01-01T00:00:00Z1H NMR Spectroscopy and MR Imaging with hyperpolarised substances
Graafen, Dirk; Neudert, Oliver; Buljubasich Gentiletti, Lisandro; Franzoni, María Belén; Dechent, Jan Falk; Münnemann, Kerstin
Despite their wide applicability in natural sciences, NMR and MRI still suffer from their inherently low sensitivity. This can be overcome by hyperpolarisation techniques, such as parahydrogen-induced polarisation and dynamic nuclear polarisation. Here, we focus on the generation of 1H-hyperpolarised substances with both methods. We especially address the severe lifetime issue of the accomplished 1H hyperpolarisation by demonstrating the production of hyperpolarised liquids in a continuous flow fashion and the storage of hyperpolarisation in slowly relaxing singlet states. Another problem of hyperpolarised proton NMR and MRI is the generation of contrast between a small amount of hyperpolarised molecules and a vast thermal background signal. In this contribution, we show the possibility to use the special signal pattern that is inherent to the hyperpolarisation method to generate excellent MRI contrast which may open up unprecedented opportunities to use the standard MRI nucleus 1H, for example, biomedical applications in future.
2014-01-01T00:00:00ZA theory for the semantics of stochastic and non-deterministic continuous systemsBudde, Carlos EstebanD'Argenio, Pedro RubenSánchez Terraf, Pedro OctavioWolovick, Nicoláshttp://hdl.handle.net/11086/191172022-10-13T11:11:08Z2014-01-01T00:00:00ZA theory for the semantics of stochastic and non-deterministic continuous systems
Budde, Carlos Esteban; D'Argenio, Pedro Ruben; Sánchez Terraf, Pedro Octavio; Wolovick, Nicolás
The description of complex systems involving physical or biological components usually requires to model complex continuous behavior induced by variables such as time, distance, speed, temperature, alkalinity of a solution, etc. Often, such variables can be quantified probabilistically to better understand the behavior of the complex systems. For example, the arrival time of events may be considered a Poisson process or the weight of an individual may be assumed to be distributed according to a log-normal distribution. However, it is also common that the uncertainty on how these variables behave makes us prefer to leave out the choice of a particular probability and rather model it as a purely non-deterministic decision, as it is the case when a system is intended to be deployed in a variety of very different computer or network architectures. Therefore, the semantics of these systems needs to be represented by a variant of probabilistic automata that involves continuous domains on the state space and the transition relation. In this paper, we provide a survey on the theory of such kind of models. We present the theory of the so-called labeled Markov processes (LMP) and its extension with internal non-determinism (NLMP). We show that in these complex domains, the bisimulation relation can be understood in different manners. We show the relation between the different bisimulations and try to understand their expressiveness through examples. We also study variants of Hennessy-Milner logic thatprovides logical characterizations of some of these bisimulations.
Preprint de capítulo del libro Lecture Notes in Computer Science book series (LNCS, volume 8453)
2014-01-01T00:00:00Z