Simple relationship between the virial-route hypernetted-chain and the compressibility-route Percus--Yevick values of the fourth virial coefficient

As is well known, approximate integral equations for liquids, such as the hypernetted chain (HNC) and Percus--Yevick (PY) theories, are in general thermodynamically inconsistent in the sense that the macroscopic properties obtained from the spatial correlation functions depend on the route followed. In particular, the values of the fourth virial coefficient $B_4$ predicted by the HNC and PY approximations via the virial route differ from those obtained via the compressibility route. Despite this, it is shown in this paper that the value of $B_4$ obtained from the virial route in the HNC theory is exactly three halves the value obtained from the compressibility route in the PY theory, irrespective of the interaction potential (whether isotropic or not), the number of components, and the dimensionality of the system. This simple relationship is confirmed in one-component systems by analytical results for the one-dimensional penetrable-square-well model and the three-dimensional penetrable-sphere model, as well as by numerical results for the one-dimensional Lennard--Jones model, the one-dimensional Gaussian core model, and the three-dimensional square-well model.Comment: 8 pages; 4 figures; v2: slight change of title; proof extended to multicomponent fluid

Monitoreo de la Actividad Física a Partir de un Modelo Basado en Redes Neuronales, con Dispositivo "Wearable"

The smart devices used for health and physical activities monitoring are elements with high presence in the market of wearables.     This work presents an estimaton method for walking speed based on a multilayer artificial neural netwok, which has been trained to obtain the ratio between this speed and the frequency of the arms motion, characteristics of each person.    In spite of using only 3 input variables (hight weight and gender), errors than less than 10% were obtained for the mentioned ratio. In addition,  the estimation algorith has been incorporated into a low cost, wrist weareable device, ehich uses a inertial measurement unit (IMU) to measure the angular velocity of one arm.  These IMUs are not common for these type of devices, but can be used to obtain more accurate speed measures than those obtained by meas of GPS units.  Thus,  the system can be used to record the physical activity with higher accuracy.Keywords: Artificial neural network, walking speed measurement, health monitoring, IMU, GPS

Assembly and dynamics of propelling ferromagnetic colloids

Treballs Finals de Màster en Física dels Sistemes Complexos i Biofísica, Facultat de Física, Universitat de Barcelona. Curs: 2022-2023. Tutors: Gaspard Junot, Pietro TiernoActive colloids is a growing field of research that studies the emergent phenomena exhibited in systems of self-propelling particles as a result of the interactions between them that could not be observed if these components were isolated. These phenomena can be observed in a wide variety of systems. In this work, I show how a collection of oscillating colloidal rotors, or simply, shakers, immersed in a viscoelastic fluid, specifically, a solution of polyacrylamide (PAAM), can display this behaviour, forming complex zig-zag dynamic bands that grow linearly in time. I have investigated the dynamics of this band growth for two different PAAM concentrations, as well as the hydrodynamic flow around these shakers for both cases. This helps understanding the complex dynamics of these fluids, having implications in soft matter physics and microfluidics and in biophysic

Safety and effectiveness of propranolol in severely burned patients: systematic review and meta-analysis

Background The objective of this systematic review was to determine the effectiveness and safety of propranolol compared to placebo or usual care for improving clinical relevant outcomes in severely burned patients (TBSA \u3e20%). Methods Relevant articles from randomized controlled trials were identified by a literature search in MEDLINE, EMBASE, and CENTRAL. We included trials involving patients with a severe burn (\u3e20% of total body surface area affected). Trials were eligible if they evaluated propranolol and compared to usual care or placebo. Two investigators independently assessed articles for inclusion and exclusion criteria and selected studies for the final analysis. We conducted a meta-analysis using a random-effects model. Results We included ten studies in our systematic review. These studies randomized a total of 1236 participants. There were no significant differences between propranolol and placebo with respect to mortality (RD −0.02 [95% CI −0.06 to 0.02]), sepsis (RD −0.03 [95% CI −0.09 to 0.04]), and the overall hospital stay (MD −0.37 [−4.52 to 3.78]). Propranolol-treated adults had a decrease in requirements of blood transfusions (MD −185.64 [95% CI −331.06 to −40.43]) and a decreased heart rate (MD −26.85 [95% CI −39.95 to −13.75]). Conclusions Our analysis indicates that there were no differences in mortality or sepsis in severely burned patients treated with propranolol compared with those who had usual care or placebo. However, the use of propranolol in these patients resulted in lower requirements of blood transfusion and lower values of heart rate. The evidence synthesized in this systematic review is limited to conclude that propranolol reduces the length of hospital stay among severely burned patients. Future trials should assess the impact of propranolol on clinically relevant outcomes such as mortality and adverse events

Vascular Smooth Muscle-Specific Progerin Expression Accelerates Atherosclerosis and Death in a Mouse Model of Hutchinson-Gilford Progeria Syndrome

Background: Progerin, an aberrant protein that accumulates with age, causes the rare genetic disease Hutchinson-Gilford progeria syndrome (HGPS). Patients who have HGPS exhibit ubiquitous progerin expression, accelerated aging and atherosclerosis, and die in their early teens, mainly of myocardial infarction or stroke. The mechanisms underlying progerin-induced atherosclerosis remain unexplored, in part, because of the lack of appropriate animal models. Methods: We generated an atherosclerosis-prone model of HGPS by crossing apolipoprotein E-deficient (Apoe(-/-)) mice with Lmna(G609G/G609G) mice ubiquitously expressing progerin. To induce progerin expression specifically in macrophages or vascular smooth muscle cells (VSMCs), we crossed Apoe(-/-)Lmna(LCS/LCS) mice with LysMCre and SM22Cre mice, respectively. Progerin expression was evaluated by polymerase chain reaction and immunofluorescence. Cardiovascular alterations were determined by immunofluorescence and histology in male mice fed normal chow or a high-fat diet. In vivo low-density lipoprotein retention was assessed by intravenous injection of fluorescently labeled human low-density lipoprotein. Cardiac electric defects were evaluated by electrocardiography. Results:Apoe(-/-)Lmna(G609G/G609G) mice with ubiquitous progerin expression exhibited a premature aging phenotype that included failure to thrive and shortened survival. In addition, high-fat diet-fed Apoe(-/-)Lmna(G609G/G609G) mice developed a severe vascular pathology, including medial VSMC loss and lipid retention, adventitial fibrosis, and accelerated atherosclerosis, thus resembling most aspects of cardiovascular disease observed in patients with HGPS. The same vascular alterations were also observed in Apoe(-/-)Lmna(LCS/LCS)SM22Cre mice expressing progerin specifically in VSMCs, but not in Apoe(-/-)Lmna(LCS/LCS)LysMCre mice with macrophage-specific progerin expression. Moreover, Apoe(-/-)Lmna(LCS/LCS)SM22Cre mice had a shortened lifespan despite the lack of any overt aging phenotype. Aortas of ubiquitously and VSMC-specific progerin-expressing mice exhibited increased retention of fluorescently labeled human low-density lipoprotein, and atheromata in both models showed vulnerable plaque features. Immunohistopathological examination indicated that Apoe(-/-)Lmna(LCS/LCS)SM22Cre mice, unlike Apoe(-/-)Lmna(G609G/G609G) mice, die of atherosclerosis-related causes. Conclusions: We have generated the first mouse model of progerin-induced atherosclerosis acceleration, and demonstrate that restricting progerin expression to VSMCs is sufficient to accelerate atherosclerosis, trigger plaque vulnerability, and reduce lifespan. Our results identify progerin-induced VSMC death as a major factor triggering atherosclerosis and premature death in HGPS.Work in Dr Andres' laboratory is supported by grants from the Spanish Ministerio de Economia, Industria y Competitividad (MEIC) (SAF2016-79490-R) and the Instituto de Salud Carlos III (AC16/00091, AC17/00067) with co-funding from the Fondo Europeo de Desarrollo Regional (FEDER, ``Una manera de hacer Europa´´), the Progeria Research Foundation (Established Investigator Award 2014-52), and the Fundacio Marato TV3 (122/C/2015). The MEIC supported Dr Hamczyk (´´Formacion de Personal Investigador´´ predoctoral contract BES-2011-043938) and Dr Villa-Bellosta (´´Juan de la Cierva´´ JCI-2011-09663 postdoctoral contract). The Instituto Universitario de Oncologia is supported by Obra Social Cajastur. The Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC) is supported by the MEIC and the Pro-CNIC Foundation, and is a Severo Ochoa Center of Excellence (award SEV-2015-0505).S

Wikis en tareas educativas. Aplicaciones de la web 2.0 en Secundaria y Bachillerato

[ES] Este trabajo de investigación se centrará en el estudio, desde el marco teórico de la pedagogía interactiva, de uno de los productos más representativos de la cultura on-line: las wikis. Esta tecnología vertebra, junto con los blogs y las redes sociales, la arquitectura de la llamada web 2.0; y, además de constituir un auténtico fenómeno de masas que está revolucionando aspectos fundamentales de nuestra cultura, representa un instrumento de mediación didáctica con enorme potencial educativo.[EN] This research will focus on the study, from the theoretical framework of interactive pedagogy, one of the most representative of the culture on-line: wikis. The technology backbone, along with blogs and social networks, the architecture of the so-called Web 2.0 and, in addition to being a true mass phenomenon that is revolutionizing the fundamental aspects of our culture, mediation is a teaching tool with great educational potential

Simulaciones de Monte Carlo-Metrópolis del almacenamiento de hidrógeno en poros plano-paralelos de BC3

Actualmente, los vehículos de hidrógeno se están convirtiendo en una alternativa a los vehículos de gasolina, al no producir emisiones de dióxido de carbono. El objetivo final sería sustituir a estos últimos e impulsar una economía basada en el hidrógeno En este trabajo fin de grado se tratará el mayor problema de los vehículos de hidrógeno: el almacenamiento efectivo y seguro de la cantidad de hidrógeno gaseoso necesaria y suficiente como para poder competir con los vehículos gasolina/diésel. Algunos materiales tienen una importante capacidad para almacenar hidrógeno. Los materiales porosos son los que van a tener un papel protagonista, debido a que una alta porosidad está directamente relacionada con una mayor capacidad de almacenar hidrógeno. En particular, este trabajo fin de grado estudia el almacenamiento de hidrógeno en poros de BC3, un material inspirado en el grafeno, y obtenido experimentalmente en 2005. El BC3 es una lámina bidimensional con estructura hexagonal parecida a la del grafeno, donde algunos átomos de carbono son substituidos por átomos de boro. El hecho de cambiar tanto la composición como la modificación ligera de la estructura introduce modificaciones en las capacidades de almacenamiento de hidrógeno. El estudio se realiza mediante simulaciones de Monte Carlo-Metrópolis en el conjunto gran canónico (μ V T) obteniendo las capacidades de almacenamiento de hidrógeno de poros de BC3 a temperatura ambiente (T = 298,15 K) en dos situaciones. En la primera, se fija la presión en 25 MPa y se varía el tamaño de los poros. En la segunda, se fija un tamaño del poro y se varía la presión. Los resultados obtenidos se comparan con los de los poros de grafeno, analizando y discutiendo los cambios resultantes en las capacidades de almacenamiento de hidrógeno.Currently, hydrogen vehicles are becoming an alternative to gasoline fuel ones since they don’t put out carbon dioxide emissions. The final target is to substitute these and give impulse to a hydrogen-based economy. This end-of-degree thesis will approach these vehicles’ biggest issue: the safe and effective storage of the necessary amount of hydrogen gas to compete with diesel/gasoline fuel cars. Some materials put forward an important hydrogen storage capacity. Porous materials are the main protagonists here, due to their high porosity, which is directly linked to a greater capacity to store the hydrogen. Specifically, this paper focuses on hydrogen storage in BC3 pores, a graphene-inspired material, which was experimentally obtained in 2005. BC3 is a bidimensional sheet, with a similar structure to that of graphene, where some of the carbon atoms have been substituted by boron ones. Changing the composition as well as the subtle modification of the structure introduces modifications to the hydrogen storage capacities. Monte Carlo-Metropolis simulations in the grand canonical ensemble (μ V T) have been done in order to study its hydrogen storage capacity at room temperature (T = 298,15 K) in two different cases: fixing the pressure at 25 MPa and changing the pores’ size, and the second one, fixing the pores’ size and increasing the pressure. The obtained results have been compared to those of graphene, analyzing the found differences.Departamento de Física Teórica, Atómica y ÓpticaGrado en Físic

Naturaleza humana

A través de la historia del hombre este ha tratado de dejar su huella, su identidad, como nos lo dice, Cesar A. Castillo P. en su libro retrato como expresión de poder, “…el arte del retrato tiene una historia milenaria que nos llega, incluso, desde más allá de los límites del arte europeo y de ello nos dan pruebas los historiadores del arte coreano y chino”. Como nos lo menciona, el retrato viene desde tiempos memorables pero a nosotros nos interesa tomarlo desde el canon de los griegos, con unas proporciones exactas y una perfección impecable. Cuando pasamos al tenebrismo con sus retratos de seres divinos como forma de salvación. En el renacimiento se observaba un aumento en la técnica como lo hizo Durero, Leonardo, Rafael, Miguel Angel y demás artistas de este tiempo que van humanizando las artes. Desde el romanticismo hasta la ilustración se advierte un mejoramiento de este humanismo porque se toma la vida cotidiana de las personas. En las vanguardias o los famosos “ismos” del siglo XIX y XX, hay un rompimiento con toda lo tradicional que se veía en el arte pero se sigue teniendo en cuenta el tema del retrato como actor principal en las obras plásticas. Cuando llega la fotografía, los primeros fotógrafos fueron artistas que adoptaron este invento innovador en sus actividades, que casi acaba con la pintura, pero lo único malo de la fotografía era que tenía una realidad “ficticia”

Detection of open phase condition in power transformers

This article deals with open phase events in power transformers, mainly related to nuclear power plants where several cases have led to a global initiative for a prompt solution for this vulnerability. Different solutions are possible, and one of them, which has already been tested at a Spanish nuclear power plant, is presented here. Field test results are presented together with simulations