Nanoscale light-matter interactions in atomic cladding waveguides.

Alkali vapours, such as rubidium, are being used extensively in several important fields of research such as slow and stored light nonlinear optics quantum computation, atomic clocks and magnetometers. Recently, there is a growing effort towards miniaturizing traditional centimetre-size vapour cells. Owing to the significant reduction in device dimensions, light-matter interactions are greatly enhanced, enabling new functionalities due to the low power threshold needed for nonlinear interactions. Here, taking advantage of the mature platform of silicon photonics, we construct an efficient and flexible platform for tailored light-vapour interactions on a chip. Specifically, we demonstrate light-matter interactions in an atomic cladding waveguide, consisting of a silicon nitride nano-waveguide core with a rubidium vapour cladding. We observe the efficient interaction of the electromagnetic guided mode with the rubidium cladding and show that due to the high confinement of the optical mode, the rubidium absorption saturates at powers in the nanowatt regime.

Ultrasonic location system

Esta tese apresenta um sistema de localização baseado exclusivamente em ultrassons, não necessitando de recorrer a qualquer outra tecnologia. Este sistema de localização foi concebido para poder operar em ambientes onde qualquer outra tecnologia não pode ser utilizada ou o seu uso está condicionado, como são exemplo aplicações subaquáticas ou ambientes hospitalares. O sistema de localização proposto faz uso de uma rede de faróis fixos permitindo que estações móveis se localizem. Devido à necessidade de transmissão de dados e medição de distâncias foi desenvolvido um pulso de ultrassons robusto a ecos que permite realizar ambas as tarefas com sucesso. O sistema de localização permite que as estações móveis se localizem escutando apenas a informação em pulsos de ultrassons enviados pelos faróis usando para tal um algoritmo baseado em diferenças de tempo de chegada. Desta forma a privacidade dos utilizadores é garantida e o sistema torna-se completamente independente do número de utilizadores. Por forma a facilitar a implementação da rede de faróis apenas será necessário determinar manualmente a posição de alguns dos faróis, designados por faróis âncora. Estes irão permitir que os restantes faróis, completamente autónomos, se possam localizar através de um algoritmo iterativo de localização baseado na minimização de uma função de custo. Para que este sistema possa funcionar como previsto será necessário que os faróis possam sincronizar os seus relógios e medir a distância entre eles. Para tal, esta tese propõe um protocolo de sincronização de relógio que permite também obter as medidas de distância entre os faróis trocando somente três mensagens de ultrassons. Adicionalmente, o sistema de localização permite que faróis danificados possam ser substituídos sem comprometer a operabilidade da rede reduzindo a complexidade na manutenção. Para além do mencionado, foi igualmente implementado um simulador de ultrassons para ambientes fechados, o qual provou ser bastante preciso e uma ferramenta de elevado valor para simular o comportamento do sistema de localização sobre condições controladas.

Dual-tracking multi-constellation GNSS front-end for high-performance receiver applications

This paper presents the design and implementation of a dual–tracking Radio Frequency (RF) front–end for a multi–constellation Global Navigation Satellite Systems (GNSS) receiver. The RF frond–end is based on the direct RF conversion architecture, which employs sub–Nyquist sampling (also known as subsampling) at RF. The dual–tracking RF front–end is composed of a few RF components that are duplicated to form the two RF channels. Employing a dual–channel Analogue–to–Digital Converter (ADC) enables synchronisation of the RF channels and minimises the errors resulting from the differences in the satellite clocks and the propagation delay between the two RF channels. The digitised GNSS signals are processed by two separate acquisition and tracking engines that are driven by the front–end’s master clock. This setup provides two synchronised receivers that are integrated onto one piece of hardware. The hardware is intended to be used for research applications such as multipath mitigation, scintillation assessment, and advanced satellite clock and spatial frame transformation modelling.

From First Contact to Close Encounters: A Developmentally Deep Perceptual System for a Humanoid Robot

This thesis presents a perceptual system for a humanoid robot that integrates abilities such as object localization and recognition with the deeper developmental machinery required to forge those competences out of raw physical experiences. It shows that a robotic platform can build up and maintain a system for object localization, segmentation, and recognition, starting from very little. What the robot starts with is a direct solution to achieving figure/ground separation: it simply 'pokes around' in a region of visual ambiguity and watches what happens. If the arm passes through an area, that area is recognized as free space. If the arm collides with an object, causing it to move, the robot can use that motion to segment the object from the background. Once the robot can acquire reliable segmented views of objects, it learns from them, and from then on recognizes and segments those objects without further contact. Both low-level and high-level visual features can also be learned in this way, and examples are presented for both: orientation detection and affordance recognition, respectively. The motivation for this work is simple. Training on large corpora of annotated real-world data has proven crucial for creating robust solutions to perceptual problems such as speech recognition and face detection. But the powerful tools used during training of such systems are typically stripped away at deployment. Ideally they should remain, particularly for unstable tasks such as object detection, where the set of objects needed in a task tomorrow might be different from the set of objects needed today. The key limiting factor is access to training data, but as this thesis shows, that need not be a problem on a robotic platform that can actively probe its environment, and carry out experiments to resolve ambiguity. This work is an instance of a general approach to learning a new perceptual judgment: find special situations in which the perceptual judgment is easy and study these situations to find correlated features that can be observed more generally.

A história dos problemas da tautócrona e da braquistócrona

Pós-graduação em Educação Matemática - IGCE

Estudo de lajes com adição de resíduo de pneu

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Daily cycling of nitric oxide synthase (NOS) in the hippocampus of pigeons (C. livia)

Abstract: Background: Nitric oxide synthase (NOS) is essential for the synthesis of nitric oxide (NO), a non-conventional neurotransmitter with an important role in synaptic plasticity underlying processes of hippocampus-dependent memory and in the regulation of biological clocks and circadian rhythms. Many studies have shown that both the NOS cytosolic protein content and its enzymatic activity present a circadian variation in different regions of the rodent brain, including the hippocampus. The present study investigated the daily variation of NOS enzymatic activity and the cytosolic content of nNOS in the hippocampus of pigeons. Results: Adult pigeons kept under a skeleton photoperiod were assigned to six different groups. Homogenates of the hippocampus obtained at six different times-of-day were used for NOS analyses. Both iNOS activity and nNOS cytosolic protein concentrations were highest during the subjective light phase and lowest in the subjective dark phase of the circadian period. ANOVA showed significant time differences for iNOS enzymatic activity (p < 0.05) and for nNOS protein content (p < 0.05) in the hippocampus. A significant daily rhythm for both iNOS and nNOS was confirmed by analysis with the Cosinor method (p < 0.05). The present findings indicate that the enzymatic activity of iNOS and content of nNOS protein in the hippocampus of pigeons exhibit a daily rhythm, with acrophase values occurring during the behavioral activity phase. Conclusions: The data corroborate the reports on circadian variation of NOS in the mammalian hippocampus and can be considered indicative of a dynamic interaction between hippocampus-dependent processes and circadian clock mechanisms.

Daily cycling of nitric oxide synthase (NOS) in the hippocampus of pigeons (C. livia)

Background: Nitric oxide synthase (NOS) is essential for the synthesis of nitric oxide (NO), a non-conventional neurotransmitter with an important role in synaptic plasticity underlying processes of hippocampus-dependent memory and in the regulation of biological clocks and circadian rhythms. Many studies have shown that both the NOS cytosolic protein content and its enzymatic activity present a circadian variation in different regions of the rodent brain, including the hippocampus. The present study investigated the daily variation of NOS enzymatic activity and the cytosolic content of nNOS in the hippocampus of pigeons. Results: Adult pigeons kept under a skeleton photoperiod were assigned to six different groups. Homogenates of the hippocampus obtained at six different times-of-day were used for NOS analyses. Both iNOS activity and nNOS cytosolic protein concentrations were highest during the subjective light phase and lowest in the subjective dark phase of the circadian period. ANOVA showed significant time differences for iNOS enzymatic activity (p < 0.05) and for nNOS protein content (p < 0.05) in the hippocampus. A significant daily rhythm for both iNOS and nNOS was confirmed by analysis with the Cosinor method (p < 0.05). The present findings indicate that the enzymatic activity of iNOS and content of nNOS protein in the hippocampus of pigeons exhibit a daily rhythm, with acrophase values occurring during the behavioral activity phase. Conclusions: The data corroborate the reports on circadian variation of NOS in the mammalian hippocampus and can be considered indicative of a dynamic interaction between hippocampus-dependent processes and circadian clock mechanisms.

Neutrino velocity measurement with the OPERA experiment in the CNGS beam

In the thesis is presented the measurement of the neutrino velocity with the OPERA experiment in the CNGS beam, a muon neutrino beam produced at CERN. The OPERA detector observes muon neutrinos 730 km away from the source. Previous measurements of the neutrino velocity have been performed by other experiments. Since the OPERA experiment aims the direct observation of muon neutrinos oscillations into tau neutrinos, a higher energy beam is employed. This characteristic together with the higher number of interactions in the detector allows for a measurement with a much smaller statistical uncertainty. Moreover, a much more sophisticated timing system (composed by cesium clocks and GPS receivers operating in “common view mode”), and a Fast Waveform Digitizer (installed at CERN and able to measure the internal time structure of the proton pulses used for the CNGS beam), allows for a new measurement with a smaller systematic error. Theoretical models on Lorentz violating effects can be investigated by neutrino velocity measurements with terrestrial beams. The analysis has been carried out with blind method in order to guarantee the internal consistency and the goodness of each calibration measurement. The performed measurement is the most precise one done with a terrestrial neutrino beam, the statistical accuracy achieved by the OPERA measurement is about 10 ns and the systematic error is about 20 ns.

Convergencias y divergencias respecto de las poéticas de la década del '60 en tres proyectos de escritura : César Fernández Moreno, Joaquín Giannuzzi y Alfredo Veiravé

La crítica especializada reconoce dos líneas dominantes en el campo intelectual argentino a partir de las producciones de las décadas del sesenta y sus prolongaciones en los setenta, aunque ambas se inscribirían en una genealogía que implica dos modos diferentes de leer la dicotomía arte/vida, una de las tensiones en las estéticas de las vanguardias históricas. Una de ellas, iniciada en los años cincuenta en torno de la famosa revista Poesía Buenos Aires, dirigida por Raúl Gustavo Aguirre, emerge como consecuencia, principalmente, del procesamiento de la vanguardia francesa [especialmente el surrealismo] y podría ser caracterizada como trascendentalismo poético [Calabrese: 2001 y 2002], un aspecto de la ideología del arte que, representado en plenitud por los poetas llamados "malditos", concibe a la poesía como un modo de vida y al poeta como vate, un ser singular, que se constituye en la poesía misma y que atisba un universo diferente al de la cotidianeidad. Mientras que la segunda de las líneas mencionadas, -surgida entre 1955, con "El solicitante descolocado" de Leónidas Lamborghini y prolongada hasta los '70- conocida como la de los "sesentistas", se instaura en polémica con la índole gratuita y estetizante del arte. Se trata de aproximar el texto a lo que se denominaba el contexto aludiendo a lo histórico-social; para ello se intenta crear un imaginario que establezca una continuidad entre la escritura y un determinado modo de ver el mundo; la literatura, inscripta así en el imperativo sartreano, debe identificarse con la praxis política y con los discursos sociales de procedencia referencial [Dalmaroni: 1993 y 1998]. Ingresan, así, elementos procedentes de la cultura popular [por ejemplo, el tango] y las jergas urbanas que construyen un simulacro de oralidad, como materiales a inscribir en la poesía, enfatizando su índole "antiliteraria": tales elementos, al desplazarse de su contexto de procedencia, generan un efecto de extrañamiento, apto para promover una estimulación de la conciencia crítica y develar los ideologemas vigentes. En este contexto, se trata de problematizar la generalización de esta periodización dicotómica, mediante el estudio de las obras de los tres poetas mencionados, instaladas en un espacio de cruce e hibridaciones entre estos mandatos y la vertiente experimental o más intelectual, por lo que no responderían a los rasgos dominantes que permitirían inscribirlos en uno u otro extremo del campo diseñado.

Convergencias y divergencias respecto de las poéticas de la década del '60 en tres proyectos de escritura : César Fernández Moreno, Joaquín Giannuzzi y Alfredo Veiravé

La crítica especializada reconoce dos líneas dominantes en el campo intelectual argentino a partir de las producciones de las décadas del sesenta y sus prolongaciones en los setenta, aunque ambas se inscribirían en una genealogía que implica dos modos diferentes de leer la dicotomía arte/vida, una de las tensiones en las estéticas de las vanguardias históricas. Una de ellas, iniciada en los años cincuenta en torno de la famosa revista Poesía Buenos Aires, dirigida por Raúl Gustavo Aguirre, emerge como consecuencia, principalmente, del procesamiento de la vanguardia francesa [especialmente el surrealismo] y podría ser caracterizada como trascendentalismo poético [Calabrese: 2001 y 2002], un aspecto de la ideología del arte que, representado en plenitud por los poetas llamados "malditos", concibe a la poesía como un modo de vida y al poeta como vate, un ser singular, que se constituye en la poesía misma y que atisba un universo diferente al de la cotidianeidad. Mientras que la segunda de las líneas mencionadas, -surgida entre 1955, con "El solicitante descolocado" de Leónidas Lamborghini y prolongada hasta los '70- conocida como la de los "sesentistas", se instaura en polémica con la índole gratuita y estetizante del arte. Se trata de aproximar el texto a lo que se denominaba el contexto aludiendo a lo histórico-social; para ello se intenta crear un imaginario que establezca una continuidad entre la escritura y un determinado modo de ver el mundo; la literatura, inscripta así en el imperativo sartreano, debe identificarse con la praxis política y con los discursos sociales de procedencia referencial [Dalmaroni: 1993 y 1998]. Ingresan, así, elementos procedentes de la cultura popular [por ejemplo, el tango] y las jergas urbanas que construyen un simulacro de oralidad, como materiales a inscribir en la poesía, enfatizando su índole "antiliteraria": tales elementos, al desplazarse de su contexto de procedencia, generan un efecto de extrañamiento, apto para promover una estimulación de la conciencia crítica y develar los ideologemas vigentes. En este contexto, se trata de problematizar la generalización de esta periodización dicotómica, mediante el estudio de las obras de los tres poetas mencionados, instaladas en un espacio de cruce e hibridaciones entre estos mandatos y la vertiente experimental o más intelectual, por lo que no responderían a los rasgos dominantes que permitirían inscribirlos en uno u otro extremo del campo diseñado.

Convergencias y divergencias respecto de las poéticas de la década del '60 en tres proyectos de escritura : César Fernández Moreno, Joaquín Giannuzzi y Alfredo Veiravé

La crítica especializada reconoce dos líneas dominantes en el campo intelectual argentino a partir de las producciones de las décadas del sesenta y sus prolongaciones en los setenta, aunque ambas se inscribirían en una genealogía que implica dos modos diferentes de leer la dicotomía arte/vida, una de las tensiones en las estéticas de las vanguardias históricas. Una de ellas, iniciada en los años cincuenta en torno de la famosa revista Poesía Buenos Aires, dirigida por Raúl Gustavo Aguirre, emerge como consecuencia, principalmente, del procesamiento de la vanguardia francesa [especialmente el surrealismo] y podría ser caracterizada como trascendentalismo poético [Calabrese: 2001 y 2002], un aspecto de la ideología del arte que, representado en plenitud por los poetas llamados "malditos", concibe a la poesía como un modo de vida y al poeta como vate, un ser singular, que se constituye en la poesía misma y que atisba un universo diferente al de la cotidianeidad. Mientras que la segunda de las líneas mencionadas, -surgida entre 1955, con "El solicitante descolocado" de Leónidas Lamborghini y prolongada hasta los '70- conocida como la de los "sesentistas", se instaura en polémica con la índole gratuita y estetizante del arte. Se trata de aproximar el texto a lo que se denominaba el contexto aludiendo a lo histórico-social; para ello se intenta crear un imaginario que establezca una continuidad entre la escritura y un determinado modo de ver el mundo; la literatura, inscripta así en el imperativo sartreano, debe identificarse con la praxis política y con los discursos sociales de procedencia referencial [Dalmaroni: 1993 y 1998]. Ingresan, así, elementos procedentes de la cultura popular [por ejemplo, el tango] y las jergas urbanas que construyen un simulacro de oralidad, como materiales a inscribir en la poesía, enfatizando su índole "antiliteraria": tales elementos, al desplazarse de su contexto de procedencia, generan un efecto de extrañamiento, apto para promover una estimulación de la conciencia crítica y develar los ideologemas vigentes. En este contexto, se trata de problematizar la generalización de esta periodización dicotómica, mediante el estudio de las obras de los tres poetas mencionados, instaladas en un espacio de cruce e hibridaciones entre estos mandatos y la vertiente experimental o más intelectual, por lo que no responderían a los rasgos dominantes que permitirían inscribirlos en uno u otro extremo del campo diseñado.

Juliana Horatia Ewing's works.

v.1. Jackanapes; The story of a short life; etc.-- v.2. Daddy Darwin's dovecot; Melchior's dream; and other tales.-- v.3. Old-fashioned fairy tales; Brothers of pity; and other tales of beasts and men.-- v.4. A great emergency; and other tales.-- v.5. Mrs. Overtheway's remembrances.-- v.6. Lob-lie-by-the-fire; The brownies; and other tales.-- v.7. A flat iron for a farthing.-- v.8. Six to sixteen.-- v.9. Jan of the windmill.-- v.10. We and the world.-- v.11. Mary's meadow; Snap-dragons; Dandelion clocks; and other stories.

Time beyond clock: time use-surveys revisited

Time use surveys -despite having represented a turning point in the study of inequalities between women and men- continue hiding care times and subtracting relevance to the qualitative dimensions of time. This due both, to the ideological conception that lies behind this type of studies that consider more relevant market process as to surveys methodology. This article analyzes the theoretical model that lies behind time use surveys and, consequently, the study of the conceptual aspects, the methodology and the potential of these surveys as an analytical instrument. The aim is to unraveling the limitations presented by the surveys to take in account the subjective dimensions of time related to the wellbeing of  people.