Thermalization and many-body localization in systems under dynamic nuclear polarization

We study the role of dipolar interactions in the standard protocol used to achieve dynamic nuclear polarization (DNP). In the so-called spin-temperature regime, where the interactions establish an effective thermodynamic behavior in the out-of-equilibrium stationary state, we provide numerical predictions for the level of hyperpolarization. We show that nuclear spins equilibrate to the effective spin-temperature established among the electron spins of radicals, as expected from the quantum theory of thermalization. Moreover, we present an analytical technique to estimate the spin temperature, and thus, the nuclear hyperpolarization in the steady state, as a function of interaction strength and quenched disorder. This reproduces both our numerical data and experimental results. Our central finding is that the nuclear hyperpolarization increases steadily upon reducing the interaction strength (by diluting the radical density). Interestingly, the highest polarization is reached at a point where the establishment of a spin temperature is just about to break down due to the incipient many-body localization transition in the electron spin system.Comment: 12 pages (+ 3 pages of appendix), 8 figure

Limiting probabilities of first order properties of random sparse graphs and hypergraphs

Let (Formula presented.) be the binomial random graph (Formula presented.) in the sparse regime, which as is well-known undergoes a phase transition at (Formula presented.). Lynch ((Formula presented.), 1992) showed that for every first order sentence (Formula presented.), the limiting probability that (Formula presented.) satisfies (Formula presented.) as (Formula presented.) exists, and moreover it is an analytic function of c. In this paper we consider the closure (Formula presented.) in the interval (Formula presented.) of the set (Formula presented.) of all limiting probabilities of first order sentences in (Formula presented.). We show that there exists a critical value (Formula presented.) such that (Formula presented.) when (Formula presented.), whereas (Formula presented.) misses at least one subinterval when (Formula presented.). We extend these results to random sparse d-uniform hypergraphs, where the probability of a d-edge is (Formula presented.)

Anti‑proliferative and cytotoxic effect of cannabidiol on human cancer cell lines in presence of serum

Objective: Cannabinoids are able to reduce tumor growth in xenograft models, but their therapeutic potential as anti-cancer drugs in humans is unclear yet. In vitro studies of the effect of cannabinoids on cancer cells are often carried out in absence of serum or in low serum concentration (i.e. 0.5% serum), conditions that limit cellular growth and therefore can increase the response of cells to additional challenges such as the presence of cannabinoids. However, the tumor microenvironment can be teaming with growth factors. In this study we assessed the viability and proliferation of cancer cells treated with cannabidiol in presence of a serum concentration that commonly sustains cell growth (10% serum). Results: The results show that cannabidiol exerts a markedly different effect on the viability of the human HT-29 cancer cell line when cultured in presence of 0.5% serum in comparison to 10% serum, displaying a cytotoxic effect only in the former situation. In presence of 10% serum, no inhibitory effect of cannabidiol on DNA replication of HT-29 cells was detected, and a weak inhibition was observed for other cancer cell lines. These results indicate that the effect of cannabidiol is cell context-dependent being modulated by the presence of growth factors

Devaluación y sustitución de importaciones en Argentina. Ensayo de actualización al año 2003 de la matriz insumo producto

Este trabajo estima el impacto de la devaluación y el consiguiente cambio de precios relativos sobre la demanda de insumos, proveyendo una estimación de la sustitución de importaciones operada desde el año 2002. Ello se realiza comparando los valores de importación efectivos y los esperables para el año 2003, a través del empleo de la Matriz de Insumo-Producto de 1997. Se obtiene así una nueva Matriz de Requisitos Directos e Indirectos para el año 2003. La misma muestra un incremento de tales requerimientos en todos los sectores, pero en particular en los sectores de Industria Manufacturera y Construcción, lo que indica que son estos sectores los que indujeron, en mayor grado, el reemplazo de insumos importados por producción nacional. En términos globales, el cálculo realizado permite aproximar una reducción de importaciones de insumos del orden de 2.500 millones de dólares, equivalente al 19% de lo que se estima se habría importado bajo las condiciones de la década del 90. Este resultado debe considerarse con cautela, por cuanto en el 2003 la economía argentina aún no había recuperado su normalidad, luego de la fuerte caída del nivel de actividad ocurrida en 2002

Colonial Settlements in the Río de la Plata: Between Transference and Development of Spanish Urban Models

Historiographic approaches to colonial settlements in the Río de la Plata—today Argentina—must consider its condition as a space for the contact between different realities. Confronting European ideas with American reality opened the possibility of innovation when faced with that which was different and experimentation when faced with the unknown. It is vital also to consider the analysis of the territory and its components as a necessary means for understanding the process of the construction of new spaces