The Federico Santa María Technical University (Spanish: Universidad Técnica Federico Santa María, UTFSM, the Prestigious one or simply Santa Maria University) is a Chilean university founded in 1926 in Valparaíso, Chile. The university has campuses in Valparaiso, Viña del Mar, Santiago (Vitacura and San Joaquín) and, as well as an international campus in Guayaquil, Ecuador. The Federico Santa María Technical University is the alma mater of several prominent businessmen, engineers and Chilean scientists. Its students and alumni are known as "Sansanos".The UTFSM was the first Chilean university to confer a doctorate in engineering in 1962 and the first higher-education institution in Latin America to confer this degree. The UTFSM university radio is the oldest campus radio in Latin America.The university admission is very competitive and, it is known for its rigorous study requirements, demanding study program, and for being the only engineering university in Chile to require physical training as a compulsory part of the curriculum in its Valparaiso and Santiago Campuses. For the years 2011–2016, the UTFSM has an undergraduate retention rate of 81.0% by the first year of studies, and a 66.4% by the second year. Less than 1% of its students are international, and most of the available courses are imparted in Spanish.The UTFSM has been historically perceived as one of the most prestigious engineering schools in the country and more recently, with the appearance of national and international rankings, has been placed among the top Universities in Chile and Latin America. It is ranked first in Chile and second in Latin America by The Times Higher Education World University Rankings 2001–2002.The graduation date is held on the 20th of December every year, since it commemorates the anniversary of the death of the founder, Federico Santa Maria Carrera, on the 20th of December 1925..
The complex geometry of biphenylene materials offers alternative routes for exploring novel stacking configurations achieved by piling up carbon-thin sheets. Here we investigate sliding-induced topological transitions in biphenylene bilayers, proposing various novel stacking configurations. They are analyzed from a symmetry perspective and described in detail, highlighting the intricate patterns of type-II Dirac cone crossings. Topological changes in the Fermi surface are assessed via the Euler characteristic, linking each transition to its corresponding symmetry, which can be experimentally tested by conductance measurements. Moreover, the ability to tune these topological properties by sliding the layers provides a simpler and more effective way to observe such phenomena.
Aortic hemodynamic parameters estimated from 4D Flow Magnetic Resonance (MR) velocity measurements are often estimated using a constant Newtonian viscosity, neglecting blood's shear-thinning behavior. The aim of this work is to estimate and assess whether Newtonian viscosity is sufficient to quantify these parameters, given the non-Newtonian nature of blood. Additionally, we demonstrate that shear-thinning effects remain observable in large vessels despite artifacts commonly present in 4D Flow MR images.. To address this, we quantified the impact of blood rheology and hematocrit (Hct) on Wall Shear Stress (WSS), the rate of viscous Energy Loss (EL), and the Oscillatory Shear Index (OSI) based on velocity data obtained from 4D Flow MR images. Using a Hct-dependent power-law non-Newtonian model with experimentally derived rheological parameters, we analyzed these metrics across a broad range of Hct values at physiological temperatures in both in-silico and in-vivo MR datasets. The results reveal significant differences between Newtonian and non-Newtonian models. In in-silico experiments, WSS and EL differed by up to +189% and +112% at systole, with reductions of-74% and-80% at diastole, respectively, while OSI differences ranged from-23% to-30%. For in-vivo data, WSS and EL deviations reached-44% and-60% at systole, ranging from-69% to +73% at diastole, with OSI differences averaging-21%. These findings highlights the importance of accounting for non-Newtonian blood rheology when estimating hemodynamic parameters from 4D Flow MR images in large vessels, enhancing the accuracy of cardiovascular disease assessments using in-vivo aortic data.
We present a new analytical approach to the longitudinal development of electromagnetic air showers, offering improvements to the classical Greisen formalism. We introduce a modified profile for the slope function lambda(1)(s) that achieves an agreement less than 0.75% with the original lambda(1) for shower age parameter s between 0.3 < s < 1.4, where s represents the stage of shower development. Our new formalism provides an improved representation of shower evolution, particularly near and beyond the shower maximum. In addition, we propose a modified Greisen profile. Our implementation includes the zenith angle dependence on the number of particles at the detector level at high altitudes, making it particularly useful for high-altitude observatories. This expression is suitable for implementing air shower simulation tool fitting procedures over a wide range of energies and geometries. Our analysis shows that the modified Greisen profile provides better agreement with the expected evolution of particle numbers compared to the Greisen formulation when we compare it with CORSIKA simulations.
Solutions of the spray flamelet equations reported in the literature during the last decade have been limited to very specific situations presenting steady evaporation profiles. Implicitly, this corresponds to the adoption of a continuous droplet injection strategy. In this work, it is shown how a relaxation of this restrictive assumption allows obtaining an entire spectrum of new solutions of the spray flamelet equations. For this, a Lagrangian description of the liquid phase in mixture fraction space is introduced, which is obtained by assuming that droplets travel along mixture fraction gradient trajectories. The resulting formulation is then employed to analyze ethanol/air non-premixed gas flamelets perturbed by mono-disperse sprays generated with continuous and discontinuous droplet injection strategies. It is observed that the latter leads to periodically oscillating solutions of the spray flamelet equations exhibiting time-averaged maximum temperatures up to 46 K higher than the ones obtained adopting the former. Additionally, a discontinuous injection strategy leads to an important extension of the ranges of initial droplet radii and velocities leading to burning flamelet structures (16% and 25%, respectively). Finally, it is illustrated how the developed approach also allows obtaining solutions of the spray flamelet equations for extinction/re-ignition phenomena, which have received no attention in the spray flamelet literature so far. The introduced formalism provides an appropriate basis for the future improvement of flamelet-based models for the simulation of turbulent spray flames. Novelty and significance This work presents the first unsteady solutions of the spray flamelet equations reported in the literature. These can be classified in two different groups: (i) Periodically oscillating unsteady flamelet structures and (ii) flamelets experiencing extinction/re-ignition phenomena. Until now, none of these had received any attention in the spray flamelet literature and, therefore, this study represents an important contribution towards the goal of bringing spray flamelet theory to the same level of development of its classical formulation for gas flames.
The cyclical dynamics of lemmings in the Arctic have garnered increasing attention over the years. The potential loss of the lemming cycle raises concerns about the collapse of the entire food chains which may include specialized predators (such as the stoat), and generalist predators (arctic fox, snowy owl, and long-tailed skua). In this paper we conduct a comprehensive investigation of the complex dynamics within a predator-prey model that incorporates both specialist and generalist predators, alongside constant prey emigration, using a dynamical systems approach. We identify several key bifurcations related to equilibrium and limit cycles, including saddle-node bifurcation, Hopf bifurcation and Bogdanov-Takens bifurcation. The presence of cusps in equilibria and limit cycles reveals mechanisms that can lead to three coexisting equilibria or limit cycles, as well as potential extinction for both populations. Additionally, we explore the Fennoscandia phenomenon by examining the interactions between specialist and generalist predators within this framework. To our knowledge, we are the first to fully uncover the real generating mechanism for three limit cycles near a codimension-2 cusp region in the context of lemming dynamics; notably, these limit cycles may bifurcate from different Hopf bifurcation points rather than originating from a single point. Our findings indicate that an increase in the presence of constant lemming emigration can expand the bistable region and resilience of the predator-prey system, accompanied by hysteresis phenomena. This suggests that these factors may enhance the robustness of the predator-prey dynamics.
