A Strontium Atomic Source for Ultracold Quantum Gas Experiments

Màster Oficial de Ciència i Tecnologia Quàntiques / Quantum Science and Technology, Facultat de Física, Universitat de Barcelona. Curs: 2021-2022. Tutors: Leticia Tarruell, Antonio Rubio AbadalIn this work we report on the construction and characterization of a strontium atomic source that will be used as a first step in the production of ultracold quantum gases. We detail the design and assembly of the atomic oven, as well as the vacuum chamber and the optical setup built for its study. We also present the results of spectroscopy measurements using quasi-resonant laser light, from which we infer information about the density and velocity profiles of the atomic beam. Finally, we implement a one-dimensional transverse cooling to enhance the collimation of the atomic beam, demonstrating an increase in the resulting atomic density

Cohomology theories of spacetimes

Treballs Finals de Grau de Matemàtiques, Facultat de Matemàtiques, Universitat de Barcelona, Any: 2021, Director: Joana Cirici[en] Recently, non-standard de Rham cohomologies with causally restricted supports have proven to be useful in ongoing theoretical physics research. In this work, we present them starting from the most elementary notions of cohomology in manifolfds and spacetime, thereby offering an overview of de Rham cohomology and an introduction to Lorentzian manifolds and their causal structure. We also characterize these cohomologies in globally hyperbolic spacetimes, exhibiting isomorphims with the standard de Rham cohomologies and providing examples of computation for some well-known physical models of the spacetime

The measurement problem in Quantum Mechanics

Treballs Finals de Grau de Física, Facultat de Física, Universitat de Barcelona, Curs: 2021, Tutor: Lluís Garrido BeltránThe measurement problem in quantum mechanics is the problem of how to conciliate the deterministic evolution of the Schrödinger equation with the random collapse experienced when a measurement is performed. This mystery is one of the most remarkable enigmas in the theory that successfully constitutes the foundation of much of modern physics. In this work we aim to expose the problem and brie y discuss the main proposed alternatives that have given rise to the socalled interpretations of quantum mechanic

Passive flow control study in a convoluted intake using Stereo Particle Image Velocimetry

The ability of vortex generators (VG) to reduce the unsteady distortion at the exit plane of an S-duct (AIP) is investigated. The 3 components of the velocity at the AIP were measured using a Stereo Particle Velocimetry system with high spatial resolution. This enabled an assessment of the synchronous swirl distortion at the duct exit. A total of nine VG cases have been investigated with a systematic variation of key design variables. Overall the VGs change the duct secondary flows and separation and are able to substantially restructure the flow field at the AIP. The pressure distortion could be reduced up to 50% and a reduction in pressure loss of 30% was achieved for the mean flow field. The VGs have a substantial influence on the unsteadiness of the flow field with a reduction in peak swirl unsteadiness of 61% and an overall reduction of unsteady swirl distortion of 67%. They also suppress the primary unsteady flow switching mechanism of the datum configuration which is associated with the oscillation of bulk and twin swirl regimes. Consequently, extreme events which leads to high swirl intensity are suppressed which lower by 45% the maximum swirl intensity for the VG cases

The Lebesgue differentiation theorem revisited

We prove a general version of the Lebesgue differentiation theorem where the averages are taken on a family of sets that may not shrink nicely to any point. These families of sets involve the unit ball and its dilated by negative integers of an expansive linear map. We also give a characterization of the Lebesgue measurable functions on R^n in terms of approximate continuity associated to an expansive linear map

Transit Timing Observations from Kepler. VIII Catalog of Transit Timing Measurements of the First Twelve Quarters

Following Ford et al. (2011, 2012) and Steffen et al. (2012) we derived the transit timing of 1960 Kepler KOIs using the pre-search data conditioning (PDC) light curves of the first twelve quarters of the Kepler data. For 721 KOIs with large enough SNRs, we obtained also the duration and depth of each transit. The results are presented as a catalog for the community to use. We derived a few statistics of our results that could be used to indicate significant variations. Including systems found by previous works, we have found 130 KOIs that showed highly significant TTVs, and 13 that had short-period TTV modulations with small amplitudes. We consider two effects that could cause apparent periodic TTV - the finite sampling of the observations and the interference with the stellar activity, stellar spots in particular. We briefly discuss some statistical aspects of our detected TTVs. We show that the TTV period is correlated with the orbital period of the planet and with the TTV amplitude.Comment: Accepted for publication to ApJ. 57 pages, 23 Figures. Machine readable catalogs are available at ftp://wise-ftp.tau.ac.il/pub/tauttv/TT

Electrochemical biosensors in pharmaceutical analysis

Given the increasing demand for practical and low-cost analytical techniques, biosensors have attracted attention for use in the quality analysis of drugs, medicines, and other analytes of interest in the pharmaceutical area. Biosensors allow quantification not only of the active component in pharmaceutical formulations, but also the analysis of degradation products and metabolites in biological fluids. Thus, this article presents a brief review of biosensor use in pharmaceutical analysis, focusing on enzymatic electrochemical sensors.Em virtude do aumento da demanda por técnicas analíticas simples e de baixo custo, os biossensores têm atraído a atenção para a análise de fármacos, medicamentos e outros analitos de interesse em controle de qualidade de medicamentos. Os biossensores permitem a quantificação não somente de princípio ativo em formulações farmacêuticas, mas também de produtos de degradação e metabólitos em fluídos biológicos, bem como análise de amostras de interesse clínico e industrial, além de possibilitar a determinação de enantiômeros. Desta forma, este artigo objetiva fazer uma breve revisão a respeito do emprego de biossensores em análise farmacêutica, com ênfase em sensores eletroquímicos enzimáticos