Ataques Especulativos: Un Enfoque de Incertidumbre e Información

Durante la década pasada hemos presenciado una proliferación de crisis cambiarias, tanto en Asia como en Europa y Latinoamérica, acompañada de abundante literatura acerca del tema. Es aceptado que, cuando las políticas monetaria y fiscal no son congruentes entre sí, habrá una crisis de balanza de pagos. La literatura reciente ha avanzado en varias direcciones para explicar los mecanismos de propagación de una crisis, que aplican aún cuando la política del gobierno es sostenible. No obstante, este tipo de modelos explica escasamente la iniciación de un ataque. El objetivo de este artículo es dar una explicación tentativa a esa iniciación. Se presenta un modelo donde la obtención de información es crucial para el inversionista y ésta se deteriora con el tiempo; en este marco, el ataque especulativo es un comportamiento óptimo para un inversionista que tenga la capacidad de llevarlo a cabo. Del modelo puede concluirse, entre otras cosas, que existe una relación inversa entre la frecuencia y la profundidad de los ataques. Además, el tamaño del agente relativo a la economía y la fuerza del efecto manada afectan de manera importante los costos del ataque y, de esta forma, afectan también la vulnerabilidad de cada economía a sufrir ataques especulativos.

Photon Self-Induced Spin to Orbital Conversion in TGG crystal at high laser power

In this paper, we present experimental evidence of a newly discovered third-order nonlinear optical process Self-Induced Spin-to-Orbital Conversion (SISTOC) of the photon angular momentum. This effect is the physical mechanism at the origin of the depolarization of very intense laser beams propagating in isotropic materials. The SISTOC process, like self-focusing, is triggered by laser heating leading to a radial temperature gradient in the medium. In this work we tested the occurrence of SISTOC in a terbium gallium garnet (TGG) rod for an impinging laser power of about 100~W. To study the SISTOC process we used different techniques: polarization analysis, interferometry and tomography of the photon orbital angular momentum. Our results confirm, in particular, that the apparent depolarization of the beam is due to the occurrence of maximal entanglement between the spin and orbital angular momentum of the photons undergoing the SISTOC process. This explanation of the true nature of the depolarization mechanism could be of some help in finding novel methods to reduce or to compensate for this usually unwanted depolarization effect in all cases where very high laser power and good beam quality are required.Comment: 6 pages, 10 figures, submitte

Durable and ductile double-network material for dust control

Dust generation is a world-wide issue due to its serious deleterious effects on the environment, human health and safety, and the economy. Although various dust suppression methods have been used for decades, some critical drawbacks in state-of-the-art technology still remain unsolved, such as short-lasting, ground water impact, and prone to water. This work reports a soil stabilizer based on non-toxic material and forms a ductile and durable double-network in soil, namely “D3 soil stabilizer”, which not only improves soil mechanical toughness of surface soil but also suppresses dust generation. A copolymer comprising hydrophilic and hydrophobic components combined with enzyme-induced carbonate precipitation is utilized as an in-situ gelation binder to soil particle. The tunable hydrophobic-to-hydrophilic component ratio minimizes undesirable soil matrix expansion and mechanical strength loss upon experiencing wet-dry processes, while still retains good water affinity. We further demonstrated controllable treatment depth by fine-tuning precursor composition, which is essential to minimize environmental impact. The double-network morphology with carbonate precipitate embedded uniformly in polymer matrix is observed via microscopic imaging. The nature of outstanding ductility, high durability against water, and good long-term stability were supported by systematic unconfined compressive strength (UCS) measurements on treated soil, which show strong inter-particles binding, good retention of peak strength, increased strain at peak strength, and increased toughness after soil samples have experienced wet-dry processes