Tuning the conductance of a molecular switch

The ability to control the conductance of single molecules will have a major impact in nanoscale electronics. Azobenzene, a molecule that changes conformation as a result of a trans/cis transition when exposed to radiation, could form the basis of a light-driven molecular switch. It is therefore crucial to clarify the electrical transport characteristics of this molecule. Here, we investigate theoretically charge transport in a system in which a single azobenzene molecule is attached to two carbon nanotubes. In clear contrast to gold electrodes, the nanotubes can act as true nanoscale electrodes and we show that the low-energy conduction properties of the junction may be dramatically modified by changing the topology of the contacts between the nanotubes and the molecules, and/or the chirality of the nanotubes (that is, zigzag or armchair). We propose experiments to demonstrate controlled electrical switching with nanotube electrodes

Spin transport in helical biological systems

Motivated by the recent experimental demonstration of spin selective effects in monolayers of double-stranded DNA oligomers, our work presents a minimal model to describe electron transmission through helical fields. Our model highlight that the lack of inversion symmetry due to the chirality of the potential is a key factor which will lead to a high spin-polarization (SP). We also study the stability of the SP against fluctuations of the electronic structure induced by static disorder affecting the on-site energies. In the energy regions where the spin- filtering occurs, our results remain stable against moderate disorders although the SP is slightly reduced

Diversification Strategies of Large Business Groups in the Philippines

This paper describes the diversification strategies of 11 major Philippine business groups.  First, it reviews the benefits and drawbacks of related and unrelated diversification from the literature.  Then, it describes the forms of diversification being pursued by some of the large Philippine business groups. The paper ends with possible explanations for the patterns of diversification observed in these Philippine business groups and identifies directions for future research

Effective Hamiltonian model for helically constrained quantum systems within adiabatic perturbation theory: application to the Chirality-Induced Spin Selectivity (CISS) Effect

The chirality-induced spin selectivity (CISS) effect has been confirmed experimentally for a large class of organic molecules. Adequately modeling the effect remains a challenging task, with both phenomenological models and first-principle simulations yielding inconclusive results. Building upon a previously presented model by K. Michaeli and R. Naaman (J. Phys. Chem C 123, 17043 (2019)) we systematically investigate an effective 1-dimensional model derived as the limit of a 3-dimensional quantum system with strong confinement and including spin-orbit coupling. Having a simple analytic structure, such models can be considered a minimal setup for the description of spin-dependent effects. We use adiabatic perturbation theory to provide a mathematically sound approximation procedure applicable to a large class of spin-dependent continuum models. We take advantage of the models simplicity by analyzing its structure to gain a better understanding how the occurrence and magnitude of spin polarization effects relate to the model's parameters and geometry

PROPUESTA DE IMPLEMENTACION DE HERRAMIENTAS LEAN MANUFACTURING EN EL ÁREA DE POST-VENTA DEL TALLER DE UNA EMPRESA DEL RUBRO AUTOMOTRIZ, PARA INCREMENTAR LA PRODUCTIVIDAD, EFICIENCIA Y REDUCIR COSTOS, AREQUIPA 2016

En el sector automotriz Peruano, el mercado se ha estabilizado en promedio en 14000,00 unidades mensuales entre vehículos ligeros y comerciales, lo cual si bien es cierto tuvo un pequeño desnivel en el 2014 de 4,8% comparado con el 2013, por la ya conocida desaceleración de la economía, sin embargo se tiene pronosticado, y se viene cumpliendo el aumento en nivel de ventas en el mercado automotriz en el 2015 y 2016, por tener nuevos proyectos de crecimiento a nivel nacional. Cabe señalar que la participación de mercado de la marca Mercedes Benz en Perú, y su único representante “Divemotor” es del 12% y ocupa el tercer lugar en el mercado de lujo Peruano, y espera incrementarse con el ingreso al mercado de nuevos modelos. Es por ello que en cuanto a servicio post- venta el nivel de atención se incrementa, debido a las ventas de años anteriores y crecimiento actual, donde la competencia, crecimiento y organización de los talleres a nivel regional y nacional es cada día más competitivo y exige mantenerse en la vanguardia de información y actualización, además esta característica en un concesionario de autos, aumenta la prioridad en casi un 20% para el cliente, en cuanto a la decisión de comprar un vehículo nuevo. Siendo el principal objetivo de la investigación insertar y aplicar continuamente las herramientas de “Lean Manufacturing”, en el servicio de post-venta, mas específicamente en un servicio piloto, siendo de adestramiento para reducir y eliminar desperdicios, utilizando el concepto de que todo lo que no agrega valor debe ser eliminado. Por último se verificara con indicadores de gestión, comprobando la productividad y la eficiencia mejoradas, así como la reducción de costos de desperdicio y se plasmara en las conclusiones, cuán importante es el método aplicado, para la organización en general, así como para seguir aplicando y mejorando el modelo de mejora continua que plantea la dirección de la organización

Urban Cargo Transport UAV Final Design Review

Delivery of goods to homes and offices over the last decades has seen a significant increase as more people and businesses need or want items sent directly to them. With the increase in demand, technology has also experienced a rapid growth, specifically in the field of unmanned aerial vehicles (UAVs). Many major companies are currently researching UAVs as the future of their delivery operations. With this ever-growing demand, NASA has issued a design competition of a UAV developed for urban deliveries. This unmanned aircraft system (UAS) would need to be able to deliver small packages, in a timely manner, within the city they operate. They must be able to drop off two lightweight packages to destinations without human intervention. They must be safe for the citizens of the cities they operate in and output low levels of sound as to not add to the noise pollution (4.4 Design Requirements and Specifications:). Various areas of development needed to be considered and analyzed. The UAV body has fixed wings with a boom-tail design and a multi-rotor configuration for the motors (Figure 7). The body of the aircraft underwent analysis in SolidWorks to gather data of its aerodynamics (5.3 Computational Fluid Simulation). With this analysis, the MH-83-iL airfoil was chose to best suit the needs of this craft (3.2.1 Main Airfoil). Through wing loading analysis, NRT’s UAV would be able to fly at cruising speed of 27 knots and have a 0.08 thrust. Other aspects to consider included control systems, budgetary analysis, and government regulations. Controls systems provide data and insurance for collision avoidance, altitude readings, thermal sensors, and GPS guidance. These systems as well as a safety parachute allow for maximum performance and precaution to help integrate it into urban life. The cost of the aircraft (4.7 Budget) comes out to roughly $1700 given our required body, systems, and propulsion systems. Lastly, government regulations with the Federal Aviation Administration (FAA) provide guidelines for registering and flying UAVs in urban environments. Working closely with the FAA would be required to ensure all federal laws are abided by. The development of and advancement of the urban air mobility (UAM) can provide a more efficient and cost-effective means of delivering packages for companies throughout the nation. This can be achieved with computational and budgetary analysis that best optimize UAV, along with proper safety and government regulations, for company use

Literatura e arte contemporânea

O artigo explora as relações entre a literatura e as práticas da arte contemporânea focando em autores como Enrique Vila-Matas, César Aira, Mario Bellatin e Kennet Goldsmith. Técnicas de montagem, apropriação, transcrição, performance aparecem como chaves para compreender os caminhos seguidos por alguns autores contemporâneos que sentem de novo um certo impasse na escrita literária