1,302 research outputs found
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
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
Sobre la lectura de las Obras de Nietzsche
Esta reflexión sobre la lectura auténtica de los filósofos fue publicada originalmente por su autor en la entrega 16 de la revista Mito (octubre-noviembre de 1957), bajo el título de “La cultura en 1957: otra vez Nietzsche”. Se trataba de un comentario generado por la aparición de una nueva edición de las Obras Completas del filósofo debida a Karl Shlechta (Munich, 1954-1957), después de un esfuerzo erudito empeñado para purificar las ediciones falsificadas y confusas previas, realizado directamente sobre los manuscritos originales conservados en el Archivo Nietzsche. La ocasión fue aprovechada por el filósofo recientemente fallecido (Sogamoso, 05.05.1928–Bonn, 27.05.2005) para indicarle a las nuevas generaciones el modo y el orden de lectura de los difíciles textos del pensador que durante la década de 1950 habían dado pie a la expresión de imposturas intelectuales entre algunos lectores de los países hispanoamericanos, las cuales oscilaron entre una recepción pseudo-romántica de unos bohemios provocadores y la acomodación de los comentaristas católicos. Esta reedición, dirigida a los jóvenes estudiantes y al público ilustrado, rescata unas indicaciones útiles para la relectura auténtica de uno de los grandes pensadores alemanes del siglo XIX
Perfil emprendedor de un grupo de alumnos del último año de una especialidad de negocios y otra de ingeniería de la Pontificia Universidad Católica del Perú en el año 2017
El presente estudio plantea la necesidad de conocer cuál es el perfil emprendedor de un
grupo de alumnos de una especialidad de negocios y una de ingeniería, determinando qué factores
son importantes para constituir un perfil emprendedor y tomando como base un cuestionario
validado; además de una serie de entrevistas a los alumnos para profundizar en ciertos factores
evaluados en el cuestionario.
La aproximación de la investigación se realiza mediante el estudio de caso de dos grupos
de alumnos pertenecientes a una especialidad de negocios y otra de ingeniería de la Pontificia
Universidad Católica del Perú. En consecuencia, la presente investigación describe la situación
actual de los dos grupos de alumnos, su predisposición al emprendimiento en base a los factores
mostrados, todo ello enmarcado en un modelo teórico.
Como resultado de este estudio, se elabora un perfil emprendedor de los grupos de
alumnos. Este sintetiza los hallazgos de la investigación, y facilita la descripción de las
características más adecuadas para impulsar el perfil emprendedor de los alumnos. Finalmente,
como resultado de la descripción del cuestionario y análisis de las entrevistas se presentan
conclusiones y recomendaciones relativas a mejoras en el desarrollo del perfil emprendedor de
los alumnos.Tesi
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