Optical sub-diffraction limited focusing for confined heating and lithography

Electronics and nanotechnology is constantly demanding a decrease in size of fabricated nanoscale features. This decrease in size has become much more difficult recently due to the limited resolution of optical systems that are fundamental to many nanofabrication methods. A lot of effort has been made to fabricate devices smaller than the diffraction limit of light. Creating devices that are capable of confining fields by means of interference patterns of propagating wave modes and surface plasmon, has proven successful to confine light into smaller spot sizes. Zone plate diffraction lenses generate spots with dimensions very close to the diffraction limit. We report the fabrication of zone plates to be used in laser direct writing of silicon nanowires. We show experimentally and with numerical models that a silicon substrate subjected to a focused spot is capable of reaching the necessary temperature for the synthesis of silicon nanowires with widths of 60 nm, which is considerably smaller than the diffraction limit of the processing laser. Nanoscale ridge apertures are devices with a great potential to confine light energy. Such apertures have been experimentally proven to create very small lithography features. We believe that these apertures can be further modified in order to achieve a practical smaller confinement in the near field region. In this thesis we discuss several attempts to design and fabricate apertures with sharp edges and implement them in a previously reported parallel lithography setup. In an attempt to use apertures for parallel fabrication of patterns, we developed a system to control the position of the near-field region with respect to a lithography substrate. To do this we use a method of interferometric-spatial- phase-imaging (ISPI). With the implementation of this method we were able to produce an array of 32X32 lines with confined widths as small as 22 nm. Nanoscale ridge apertures were also studied to be used as near field transducers for heat-assisted magnetic recording. They have the capability of transmitting and confining enough energy to increase the temperature of a recording medium without reaching detrimental temperatures themselves. Numerical methods are presented to prove theoretically that a well-designed aperture performs well as a near field transducer. The size of the spot region focused by the aperture could allow us to record data with higher area density than current conventional methods

Efecto de un intervalo de retención entre la pre-exposición y el condicionamiento sobre la inhibición latente en humanos con un procedimiento de condicionamiento palpebral

El fenómeno de la inhibición latente se refiere al retraso que se observa cuando se presenta repetidamente sin consecuencias un estímulo que va a ser posteriormente condicionado. En este trabajo empleamos un procedimiento de condicionamiento palpebral para analizar la inhibición latente en participantes humanos. El Experimento 1 reveló que el procedimiento empleado era adecuado para reproducir el efecto de inhibición latente. En el Experimento 2, la introducción de un intervalo de tres minutos entre las fases de pre-exposición y condicionamiento dio lugar a la atenuación de la inhibición latente. Estos resultados contribuyen a la identificación de los mecanismos que participan en la pre-exposición y posterior condicionamiento de un estímulo, aspectos particularmente importantes si tenemos en cuenta que el fenómeno de la inhibición latente ha sido utilizado repetidamente como un instrumento para analizar el curso del proceso atencional tanto en poblaciones normales como con determinadas psicopatologías.Latent inhibition, retarded learning after pre-exposure to the to-be-conditioned stimulus, was examined using a blink conditioned procedure in humans. Experiment 1 showed that the procedure is suited to inducing the latent inhibition effect. In Experiment 2, the introduction of a 3-minute interval between pre-exposure and conditioning phases attenuated latent inhibition. These results contribute to identify the mechanisms involved in pre-exposure and subsequent conditioning of a stimulus, which is particularly important if we bear in mind that latent inhibition has been used repeatedly as an instrument to analyse the course of attentional processes in normal and pathological populations

Interrupción del efecto de inhibición latente por la administración de Mk-801

Los receptores -metil-D-aspartato (NMDA) parecen estar implicados en el retraso en la adquisición de una asociación pavloviana tras la preexposición sin consecuencias al que se va a convertir en estímulo condicionado, efecto al que se suele denominar Inhibición Latente (IL). Concretamente, la administración de compuestos antagonistas en la fase de preexposición o en las fases de preexposición y condicionamiento produce un efecto disruptivo sobre la expresión de la IL cuando se utiliza un procedimiento de aversión condicionada al sabor. En este trabajo describimos tres experimentos que replican el efecto del MK-801 sobre la IL (Experimento 1) y que demuestran la persistencia de la influencia de la droga independientemente del número de ensayos de preexposición (Experimento 2), o de la intensidad del EC empleado (Experimento 3). Los resultados se interpretan en relación a los modelos psicológicos y farmacológicos relacionados con la investigación y el tratamiento clínico de diversos desordenes neurocognitivos

La reestructuración de deuda soberana y la necesidad de su regulación a través de un marco legal internacional vistas desde la perspectiva del Análisis Económico del Derecho

Determina si la implementación de un marco legal internacional, que regule el proceso de reestructuración de deuda soberana, es más eficiente económicamente y permite maximizar más el bienestar social que un enfoque contractual que suponga la adopción de cláusulas de agregación en la votación. Esta investigación aborda los problemas que rodean al proceso de reestructuración de la deuda soberana con la ayuda de herramientas del Análisis Económico del Derecho, analizando cada una de las alternativas a través de las cuales transita este proceso, pasando de un escenario sin cláusulas de acción colectiva (escenario actual de la mayoría de los bonos emitidos hasta la fecha), a uno dónde la existencia de dichas clausulas modifican las reglas de negociación, introduciendo mecanismos de agregación en la decisión colectiva de los acreedores respecto a una reestructuración. Finalmente, también se desarrolló un modelo hipotético en el que se asumió la existencia de un marco regulatorio internacional de obligatorio cumplimiento para todas las partes, el cual establece, además de los mecanismos de agregación en la votación, el derecho de un país a reestructurar su deuda. Todo esto para determinar cuál de los siguientes escenarios está más cerca de la eficiencia y permite un mayor beneficio social.Perú. Programa Nacional de Becas y Crédito Educativo (Pronabec). Beca Presidente de la Repúblic

Emprendimiento femenino y desempeño de las empresas en la República de Chile

Las mujeres están asumiendo en las últimas décadas un rol significativo en la creación de empresas y en el desarrollo económico gracias al cambio global en lo geopolítico y en la política económica de un importante número de países en todo el mundo. Como propietarias de pequeños negocios contribuyen al desarrollo en países emergentes, como el caso de Chile. El emprendimiento se ha postulado como una de las principales vías para que las mujeres logren mejorar su nivel económico y social superando una situación de desigualdades y discriminación difíciles de remontar. El trabajo aporta un modelo de desempeño de pequeños negocios con los principales factores que inciden en él, tomando como base modelos precedentes, así como su aplicación a la realidad del emprendimiento chileno. El estudio empírico revela como principales factores el tener una involucración previa en negocios anteriores, contar con el conocimiento y la experiencia para iniciar negocios, pertenecer a redes, la cantidad de horas dedicadas al negocio, el sector de actividad y la participación de la familia en el financiamiento del negocio. Los datos muestran un perfil de las mujeres emprendedoras chilenas con carencias en el nivel de formación, experiencia, pertenencia a redes, y cuya principal motivación para emprender es la “necesidad”, con el objetivo principal de “mejorar su calidad de vida”.Women are taking over the last decades a significant role in business creation and economic development through global change in the geopolitical and economic policy in a number of countries worldwide. As small business owners contribute to development in emerging countries such as the case of Chile. The venture has been postulated as one of the main ways for women to achieve better economic and social level overcoming a difficult situation of inequality and discrimination to overcome. This study provides a model of small business performance with the main factors that affect it, on the previous base models, and their application to the reality of the Chilean entrepreneurship. The empirical study reveals the main factors have prior involvement in past business have the knowledge and experience to start a business belonging to networks, the number of hours devoted to business, the business sector and the participation of the family in business financing. The data shows a profile of Chilean women entrepreneurs lacking in the level of training, experience, membership of networks, whose main motivation to undertake is the "need " with the main objective of "improving their quality of life"

Optical nanolithography with λ/15 resolution using bowtie aperture array

We report optical parallel nanolithography using bowtie apertures with the help of the interferometric-spatial-phase-imaging (ISPI) technique. The ISPI system can detect and control the distance between the bowtie aperture, and photoresist with a resolution of sub-nanometer level. It overcomes the difficulties brought by the light divergence of bowtie apertures. Parallel nanolithography with feature size of 22 ± 5 nm is achieved. This technique combines high resolution, parallel throughput, and low cost, which is promising for practical applications.United States. Defense Advanced Research Projects Agency (Grant N66001-08-1-2037)National Science Foundation (U.S.) (Grant CMMI-1120577

Sub-diffraction Laser Synthesis of Silicon Nanowires

We demonstrate synthesis of silicon nanowires of tens of nanometers via laser induced chemical vapor deposition. These nanowires with diameters as small as 60 nm are produced by the interference between incident laser radiation and surface scattered radiation within a diffraction limited spot, which causes spatially confined, periodic heating needed for high resolution chemical vapor deposition. By controlling the intensity and polarization direction of the incident radiation, multiple parallel nanowires can be simultaneously synthesized. The nanowires are produced on a dielectric substrate with controlled diameter, length, orientation, and the possibility of in-situ doping, and therefore are ready for device fabrication. Our method offers rapid one-step fabrication of nano-materials and devices unobtainable with previous CVD methods

High precision dynamic alignment and gap control for optical near-field nanolithography

The authors demonstrate the use of interferometric-spatial-phase-imaging (ISPI) to control a gap distance of the order of nanometers for parallel optical near-field nanolithography. In optical near-field nanolithography, the distance between the optical mask and the substrate needs to be controlled within tens of nanometers or less. The ISPI technique creates interference fringes from checkerboard gratings fabricated on the optical mask, which are used to determine the gap distance between the mask and the substrate surfaces. The sensitive of this gapping technique can reach 0.15 nm. With the use of ISPI and a dynamic feedback control system, the authors can precisely align the mask and the substrate and keep variation of the gap distance below 6 nm to realize parallel nanolithography. (C) 2013 American Vacuum Society

Precision Landing of a Quadrotor UAV on a Moving Target Using Low-Cost Sensors

With the use of unmanned aerial vehicles (UAVs) becoming more widespread, a need for precise autonomous landings has arisen. In the maritime setting, precise autonomous landings will help to provide a safe way to recover UAVs deployed from a ship. On land, numerous applications have been proposed for UAV and unmanned ground vehicle (UGV) teams where autonomous docking is required so that the UGVs can either recover or service a UAV in the field. Current state of the art approaches to solving the problem rely on expensive inertial measurement sensors and RTK or differential GPS systems. However, such a solution is not practical for many UAV systems. A framework to perform precision landings on a moving target using low-cost sensors is proposed in this thesis. Vision from a downward facing camera is used to track a target on the landing platform and generate high quality relative pose estimates. The landing procedure consists of three stages. First, a rendezvous stage commands the quadrotor on a path to intercept the target. A target acquisition stage then ensures that the quadrotor is tracking the landing target. Finally, visual measurements of the relative pose to the landing target are used in the target tracking stage where control and estimation are performed in a body-planar frame, without the use of GPS or magnetometer measurements. A comprehensive overview of the control and estimation required to realize the three stage landing approach is presented. Critical parts of the landing framework were implemented on an AscTec Pelican testbed. The AprilTag visual fiducial system is chosen for use as the landing target. Implementation details to improve the AprilTag detection pipeline are presented. Simulated and experimen- tal results validate key portions of the landing framework. The novel relative estimation scheme is evaluated in an indoor positioning system. Tracking and landing on a moving target is demonstrated in an indoor environment. Outdoor tests also validate the target tracking performance in the presence of wind