Blow up profiles for a quasilinear reaction-diffusion equation with weighted reaction

We perform a thorough study of the blow up profiles associated to the following second order reaction-diffusion equation with non-homogeneous reaction: $$\partial_tu=\partial_{xx}(u^m) + |x|^{\sigma}u^p,$$ in the range of exponents $10$. We classify blow up solutions in self-similar form, that are likely to represent typical blow up patterns for general solutions. We thus show that the non-homogeneous coefficient $|x|^{\sigma}$ has a strong influence on the qualitative aspects related to the finite time blow up. More precisely, for $\sigma\sim0$, blow up profiles have similar behavior to the well-established profiles for the homogeneous case $\sigma=0$, and typically \emph{global blow up} occurs, while for $\sigma>0$ sufficiently large, there exist blow up profiles for which blow up \emph{occurs only at space infinity}, in strong contrast with the homogeneous case. This work is a part of a larger program of understanding the influence of unbounded weights on the blow up behavior for reaction-diffusion equations

New Mexico: Round 1 - State-Level Field Network Study of the Implementation of the Affordable Care Act

This report is part of a series of 21 state and regional studies examining the rollout of the ACA. The national network -- with 36 states and 61 researchers -- is led by the Rockefeller Institute of Government, the public policy research arm of the State University of New York, the Brookings Institution, and the Fels Institute of Government at the University of Pennsylvania.New Mexico is no longer one of the key battleground states as it has moved more Democratic in recent presidential races, a trend driven by Latino population growth and a shift to the Democratic Party among that population. During the 2013 legislative session, Senate Bill 221 passed and authorized the establishment of a state-run New Mexico Health Insurance Exchange (NMHIX). On March 28, 2013, the governor signed Senate Bill 221 into law. Another major ACA-related decision involved Medicaid. Given the aggressive opposition from other Republican governors to the ACA, Martínez surprised some observers when she announced in early 2013 that New Mexico would expand Medicaid as long as the federal government provided the funding for the initial expansion

Impact of Technical Barriers to Trade on Argentine Exports and Labor Markets

While tariff and quota barriers in agricultural, food and manufactured products have been declining due to the proliferation of multilateral trade agreements, there is increasing debate regarding the impact of product and process standards and technical regulations, since they may have become a subtler form of protection. One of the possible effects of increasing standards in developing countries is that it may affect the size of the exporting sector, with adverse effects on labor markets. We test such effect for the case of Argentina using firm level data for the manufacturing sector. We find evidence of a reduction in export shares due to an increase in standard stringency. Moreover, there is an increase in the skill ratio for exporting firms. The overall effect of standard stringency on average wages of exporting firms is negative, supporting the idea that lower net producer prices, due to a higher cost of standard compliance, are passed on to workers.

The Emergence of New Successful Export Activities in Argentina: Self-Discovery, Knowledge Niches, or Barriers to Riches?

This paper examines the emergence of three new successful export activities in Argentina: biotechnology applied to human health, blueberries and chocolate confections. The main interest lies in ascertaining why these sectors/products were targeted, on which previously accumulated capabilities they were built upon, and what type of hurdles they faced and how they were overcome. In the absence of government support for discovery, these new exports emerged because the pioneers could introduce permanent or dynamic barriers to entry to compensate for the knowledge externalities they generated. When they could only introduce temporary barriers to entry, laissez faire investment in experimentation was suboptimally small. These new exports emerged in sectors where there were entrepreneurs with superior planning and networking skills and/or there were larger firms that could self-provide the required public goods and solve coordination failures by themselves.

Estudio de interfases en óxidos complejos por técnicas avanzadas de microscopía electrónica

Tesis inédita de la Universidad Complutense de Madrid, Facultad de Ciencias Físicas, leída el 07-05-2015Pequeños cambios a nivel atómico de la estructura, composición o estado electrónico de un material pueden producir sorprendentes efectos macroscópicos. En particular, en óxidos complejos basados en metales de transición, un gran número de fenómenos físicos como transiciones metal-aislante, magnetorresistencia colosal o multiferroicidad son extremadamente sensibles a estas variaciones. Por tanto, para abordar el estudio de sistemas con tales características, técnicas experimentales con capacidad de analizar materiales a escala atómica y en el espacio real se hacen indispensables. La microscopía electrónica de transmisión con barrido combinada con la espectroscopia de pérdida de energía de electrones (EELS) forman una pareja con posibilidades únicas para estos estudios. Estas técnicas han crecido enormemente desde el desarrollo del corrector de aberración esférica en la última década y su alta resolución espacial nos permite ahora estudiar átomos individuales. El uso de estos equipos supone una herramienta única para el estudio de sistemas complejos, más aún cuando la dimensionalidad se reduce a pocos nanómetros como en películas delgadas o interfaces. En estos casos, técnicas de difracción promediadas macroscópicamente pueden no ser suficientemente sensibles a los parámetros que rigen la física relevante y por tanto, la gran sensibilidad espacial de la microscopía electrónica supone una gran ventaja. El objetivo principal de este trabajo será precisamente establecer la conexión entre los mecanismos a nivel atómico y las propiedades físicas de una serie de sistemas basados en óxidos complejos cuidadosamente escogidos. Analizaremos en el espacio real fluctuaciones mínimas, casi por debajo del umbral de detectabilidad, responsables últimas del comportamiento macroscópico.En primer lugar, se ha estudiado como pequeñas concentraciones de vacantes de oxígeno, tanto inducidas mediante irradiación como intrínsecas al material, pueden determinar las propiedades físicas macroscópicas del sistema. Se ha observado cómo procesos de irradiación dan lugar a la formación de una capa de TiO con alto grado cristalino en la superficie de monocristales de TiO2 y como además pueden producir estados metálicos superficiales en un aislante de bandas como es el SrTiO3. Se ha analizado además como la reestructuración electrónica debida a la presencia de vacantes de oxígeno estructurales explica por primera vez el origen electroestático del bloqueo iónico en fronteras de grano de materiales con importantes aplicaciones energéticas. Se ha abordado también el estudio de pequeñas variaciones estructurales, en particular, distorsiones colectivas de la red de oxígeno en heteroestructuras de óxidos complejos y su relación con la aparición de estados físicos inexistentes en los materiales masivos. Se ha encontrado una correlación entre rotaciones del octaedro de oxígenos producidas por tensiones epitaxiales y la estabilización de una fase interfacial ferromagnética y conductora en superredes formadas por óxidos aislantes. Además, se ha extendido este análisis a sistemas más complejos como uniones túnel multiferroicas donde se ha obtenido la configuración de dominios ferroeléctricos midiendo las distorsiones en la red de oxígenos para cada celda unidad. Este estudio muestra una de las primeras observaciones experimentales de una configuración de dominios ferroeléctricos tipo head-to-head en capas ultra-delgadas. Se ha encontrado además la presencia de una carga de apantallamiento confinada a la pared de dominio que genera estados electrónicos accesibles en el interior de la barrera ferroeléctrica, proporcionando los mecanismos para estabilizar un tuneleamiento cuántico resonante.El continuo desarrollo de estas técnicas experimentales hace vislumbrar un futuro prometedor tanto para la ciencia de materiales como para la microscopía electrónica. La exploración a escala atómica de fenómenos físicos aún por desvelar está ahora, más que nunca a nuestro alcance.Fac. de Ciencias FísicasTRUEunpu

Analysis of neural networks. Applications to interpretability and uncertainty

Treballs Finals de Grau de Matemàtiques, Facultat de Matemàtiques, Universitat de Barcelona, Any: 2020, Director: Antoni Benseny i Alberto Rubio Muñoz[en] From image creation and pattern recognition to speech and text processing, the outstanding performance of neural networks in a wide variety of fields has made them a popular tool among researchers. However, the fact that we do not fully understand why their performance is so successful or how they operate converts this technology into a black-box model based on trial and error. In this work, we attempt to give deep neural networks a mathematical representation and present different examples and applications that bring light to the understanding of neural networks’ behaviour and usage

Interior eigenstates of strongly correlated quantum systems

Treballs Finals de Grau de Física, Facultat de Física, Universitat de Barcelona, Curs: 2020, Tutor: Sofyan IblisdirWe present a new method to compute states of quantum spin systems with high energy and low energy variance. Such states appear to play an important role in investigating current open problems in condensed matter physics. By minimizing the energy variance with a modification of the power method algorithm we obtain, from initial random states, states with low energy variance and their energy located in the middle of the spectrum. We test our method for a system of eight particles, four different instances of the Heisenberg model and one of the Ising mode

Lobbying, innovation and protectionist cycles

This paper explains why trade liberalizations occur in developing countries, and why they are often reversed. It does so by focusing on the use of lobbying for protection by import competing firms as a means to postpone costly product quality upgrades to keep up with foreign competitors. Given the availability of a political market for import tariffs, domestic firms will lobby for a sequence of tariffs that insulate domestic profits from a widening quality gap, thereby allowing adjustment to be postponed. But as the contributions required by the government grow with the size of the quality gap, it will be optimal to adjust quality and to decrease the lobbying effort at some time, leading to liberalization and technological catch-up. But then the equilibrium tariff will again be small and "cheap", and it will pay to start lobbying anew, until the next quality adjustment. Therefore, cycles in protection will occur as a result of the use of lobbying as a substitute for innovation. The model thus sheds new light on the impact of the costs of protection on the effectiveness of the lobbying effort over time, and on their implications for the timing and the time horizon of trade reforms in developing countries.Quality ladders, north-south trade, imitation, endogenous tariffs, lobbying, trade liberalization, cycles