Las tragedias de Amia y Cromañón : el hospital en la emergencia asistencial

Fil: Gherardi, Carlos R. Universidad de Buenos Aires. Hospital de Clínicas José de San Martín; Argentina.Fil: Jorge, Miguel A. Universidad de Buenos Aires. Hospital de Clínicas José de San Martín; Argentina.La Universidad de Buenos Aires y la propia Ciudad de Buenos Aires tienen el privilegio de tener hoy\ntodavía un Hospital Universitario enclavado en pleno centro geográfico de la ciudad, y donde hace\nmucho más que cien años se concentra el esfuerzo en la formación del recurso humano necesario\npara atender la salud de la comunidad. En esta última década, precisamente en sus extremos, 1994 y\n2004, el Hospital de Clínicas tuvo que actuar en las dos catástrofes no naturales más terribles que\nasolaron a nuestro país, y que quedarán también registradas en el mundo por su magnitud, en un caso\nproducto del terrorismo (AMIA) y en otro como resultado de la negligencia y el infortunio (incedio en\nRepública Cromañón)

Optimal Control for Vehicle Cruise Speed Transfer

The contribution of this paper consists in a procedure to solve the optimal cruise control problem that consists in transferring the car velocity between two specified values, in a fixed interval of time, with minimum fuel consumption. The solution is obtained by applying a recursive numerical algorithm that provides an approximation to the condition provided by Pontryagin’s Optimum Principle. This solution is compared with the one obtained by using a reduced complexity linear model for the car dynamics that allows an exact (“analytical”) solution of the corresponding optimal control problem. This work has been performed within the framework of activity 2.4.1 – Smart drive control of project SE2A - Nanoelectronics for Safe, Fuel Efficient and Environment Friendly Automotive Solutions, ENIAC initiative

Selection of low swelling materials for protein adsorption from white wines

The protein adsorption capacity of different materials was evaluated to assess their potential efficacy as alternative adsorbents for the removal of proteins from wines, with the purpose of finding suitable low-swelling materials that could be used in a percolated bed. The adsorbents tested were thermally treated sodium bentonite, low-swelling adsorbing clays, ion exchange resins and other protein adsorbents (silica gel, hydroxyapatite and alumina). The materials were evaluated by analysing both the capacity to stabilize untreated white wines, according to a heat test, and by characterizing the adsorption isotherms of bovine serum albumin (BSA) in a model wine (water, ethanol and K-bitartrate). Breakthrough curves in a packed bed were determined experimentally for some materials, showing the influence of the adsorption isotherm shape. Some ionexchange resins showed a favourable behaviour and have good potential as alternative adsorbents

Insights on bubble encapsulation after drop impact on thin liquid films

The accurate understanding of the phenomenology of drop impact onto dry/ wetted and cold/heated surfaces is increasingly relevant to implement biofuels in civil aviation. The outcome of drop impact depends on the pre-impact conditions and a seldom researched event is the encapsulation of a bubble when this impact occurs on thin liquid films. Therefore, the goal of the experimental work reported is to investigate the mechanism of this bubble encapsulation. Results show that the mechanism leading to a bubble formation has two stages. In the first stage, after the drop impacts a steady liquid film, a prompt splash occurs followed by a crown splash. The uprising sheet propagates in an almost normal direction relative to the liquid film, but its radius at the base continues to expand, eventually leading to the inward collapse of the crown-bounding rim encapsulating air inside the dome. In the second stage, three different phenomenologies of bubble encapsulation can occur. At the top of the closed crown, one jet (phenomenology 1) or two jets are formed (phenomenologies 2 and 3). For phenomenology 2, the upward jet eventually collapses due to gravitational influence, while the downward jet continues to grow until it reaches the liquid film, attaching to it, stretching and detaching from the top at the hemispheric thin sheet, forming a bubble. In phenomenology 3, the upward jet is high enough to allow its breakup and ejection of one large droplet before the collapse of the upward jet. Many secondary droplets fall on the bubble and one of them will eventually break the dome, leading to more secondary atomization. Additionally, the first perturbation imposed on the liquid film by the droplet impact is studied and an empirical correlation is proposed for its propagation velocity. Finally, bubble geometry is investigated.Fundação para a Ciência e a Tecnologiainfo:eu-repo/semantics/publishedVersio

Analysis And Visualization Of The Perturbations Imposed On The Liquid Film By Crown Sheet Collapse Or Closure

Bubble encapsulation is a phenomenon that results from droplet impact on a liquid film for very specific impact conditions. After splashing, the crown liquid sheet starts to bend inwards, and eventually, the jets at the top of the crown merge and form a perfect empty bubble. This bubble bursts due to the impingement of a secondary droplet that falls in the spherical dome or by reaching its critical thickness. However, bubble encapsulation is seldom reported in the literature. Due to that, this work focuses on understanding better its dynamics and formation mechanisms. By using a bottom perspective of the phenomenon, important information about its dynamics is disclosed. From the bottom shadowgraphs, the capillary waves and the perturbations imposed on the steady liquid film are clearly observed. From previous works, it was confirmed that its occurrence is systematic, so, one of the goals of this study is to realize how the impact conditions influence the phenomenon and if we can establish a criterion for its occurrence. Despite the scarce information about the phenomenon, there are some works about it that are focused on the cavity underneath the bubble. In this study, we observed the cavity and conclude that the cavity shape does not influence the bubble encapsulation phenomenon. Finally, the crown closure time was measured for a specific set of impact conditions and it was analyzed depending on the dimensionless thickness of the liquid film.Fundação para a Ciência e a Tecnologiainfo:eu-repo/semantics/publishedVersio

Insights on Bubbling Formation after Drop Impact on Thin Liquid Films

Over the years, the phenomena obtained when a drop impinges upon a dry, wetted or heated surface have been thoroughly studied. In previous works, the existence of splash was investigated by the authors with the goal of evaluating the possible implementation of biofuels in the civil aviation and it was found an episode of a phenomenon, seldom reported in the literature under specific pre-impingement conditions. The mechanism that leads to a bubble formation has two stages. After the drop impacts a steady liquid film, prompt splash occurs followed by crown splash. In the first stages of crown splash, the uprising sheet propagates almost normal to the liquid film, but its radius at the base continues to expand, eventually leading to the inward collapse of the crown bounding rim. Thus, the top of the crown closes in a bubble-like shape with the formation of two jets, one upwards and other downwards. The upward jet eventually disappears due to gravitational influence, while the downward jet continues to grow until it reaches the liquid film, attaching to it, stretching and detaching from the top at the hemispheric thin-sheet, forming a perfect bubble. Many secondary droplets fall on the bubble and one of them will eventually break the dome, leading to more secondary atomization. The few works reported in the literature referring to this phenomenon as “bubbling” or “floating bubble,” scarcely explore the hydrodynamic mechanism associated with this bubble formation and occurrence, mainly focusing on droplets impacting upon deep pools. However, in a previous study, the authors observed this event for a liquid film dimensionless thickness of 0:5 in a fluid mixture of Jet A-1 and biofuel NEXBTL. In this study, the impact conditions in the experiments performed allow to recreate the floating bubble with 100% of occurrence. After that, the authors present an extensive characterization of the bubbling phenomenon to understand better the mechanisms which lead to its formation, as well as its practical significance. A high-speed digital camera acquires several images of the floating bubble formation from different points of view (side and bottom). Namely, capturing the phenomenon from below, high-quality images allow retrieving essential data to describe the hydrodynamic mechanism accurately. The most relevant features include the bubble height and diameter, and the propagation velocity of the first perturbation imposed on the liquid film.info:eu-repo/semantics/publishedVersio

Uniform discretizations: a new approach for the quantization of totally constrained systems

We discuss in detail the uniform discretization approach to the quantization of totally constrained theories. This approach allows to construct the continuum theory of interest as a well defined, controlled, limit of well behaved discrete theories. We work out several finite dimensional examples that exhibit behaviors expected to be of importance in the quantization of gravity. We also work out the case of BF theory. At the time of quantization, one can take two points of view. The technique can be used to define, upon taking the continuum limit, the space of physical states of the continuum constrained theory of interest. In particular we show in models that it agrees with the group averaging procedure when the latter exists. The technique can also be used to compute, at the discrete level, conditional probabilities and the introduction of a relational time. Upon taking the continuum limit one can show that one reproduces results obtained by the use of evolving constants, and therefore recover all physical predictions of the continuum theory. This second point of view can also be used as a paradigm to deal with cases where the continuum limit does not exist. There one would have discrete theories that at least at certain scales reproduce the semiclassical properties of the theory of interest. In this way the approach can be viewed as a generalization of the Dirac quantization procedure that can handle situations where the latter fails.Comment: 17 pages, Revtex, no figures, published versio

Gas-phase molecular structure and energetics of anionic silicates

The gas-phase stabilities of linear, branched and cyclic silicates made of up to five silicon atoms were studied with density functional theory (DFT). The starting geometries for the DFT calculations at the B3LYP/6-311+G(2d,2p) level of theory were obtained from classical molecular dynamics simulations. We have observed that geometric parameters and charges are mainly affected by the degree of deprotonation. Charges on Si atoms are also influenced by their degree of substitution. The enthalpy of deprotonation of the neutral species was found to decrease with the size of the molecule, while the average deprotonation enthalpy of highly charged compounds increased with molecular size. Furthermore, the formation of rings in highly charged silicates is enthalpically preferred to chain growth. These observations result from two competing effects: the easier distribution of negative charge in silicates with low charge density and the strong intramolecular repulsions present in silicates with high charge density. As a consequence, highly charged silicates in the gas phase tend to be as small and as highly condensed as possible, which is in line with experimental observations from solution NMR

Study of the Saldanha Massif (MAR, 36 degrees 34 ' N): Constrains from rock magnetic and geophysical data

We present a study of the magnetic properties of a group of basalt samples from the Saldanha Massif (Mid-Atlantic Ridge - MAR - 36degrees 33' 54" N, 33degrees 26' W), and we set out to interpret these properties in the tectono-magmatic framework of this sector of the MAR. Most samples have low magnetic anisotropy and magnetic minerals of single domain grain size, typical of rapid cooling. The thermomagnetic study mostly shows two different susceptibility peaks. The high temperature peak is related to mineralogical alteration due to heating. The low temperature peak shows a distinction between three different stages of low temperature oxidation: the presence of titanomagnetite, titanomagnetite and titanomaghemite, and exclusively of titanomaghemite. Based on established empirical relationships between Curie temperature and degree of oxidation, the latter is tentatively deduced for all samples. Finally, swath bathymetry and sidescan sonar data combined with dive observations show that the Saldanha Massif is located over an exposed section of upper mantle rocks interpreted to be the result of detachment tectonics. Basalt samples inside the detachment zone often have higher than expected oxidation rates; this effect can be explained by the higher permeability caused by the detachment fault activity