Quantum Cryptography: an Overview from Physics Foundations to Engineering Development

Quantum cryptography is a relatively new field (which began to be developed in 1984), which seems to be taking its last steps to become commercially available, thus becoming the first directly quantum technology to do so. The motivation behind it is not small, since it will allow coding a message in an absolutely secure and illegible way, due to the laws of quantum mechanics, and independently of the power of any computer, even a quantum one. In what seems like a not-too-distant future, engineers who understand and are able to work with such systems will be needed. Therefore, this Master’s Thesis aims to give an introduction to the current development of the field, from the physical concepts that underlie it, to the state of the art of the technology. The text is intended for people with a background in Electrical Engineering, and little or no knowledge of quantum mechanics. However, other readers with a background in engineering or physics will also be able to take advantage of it. After reading it, the reader will be able to have a good starting point in the field, from which to continue developing their work.La criptografía cuántica es un campo relativamente nuevo (empezó a desarrollarse en 1984), que parece estar dando sus últimos pasos para poder llegar a ser comercializable, convirtiéndose, de esta forma, en la primera tecnología directamente cuántica que lo consiga. La motivación detrás de ella no es pequeña, ya que permitirá codificar un mensaje de forma absolutamente segura e indescifrable, debido a las leyes de la mecánica cuántica, e independientemente de la potencia de cualquier ordenador, incluso uno cuántico. En lo que parece un futuro no muy lejano, se comenzarán a necesitar ingenieros que comprendan y sean capaces de trabajar con este tipo de sistemas. Por ello, este trabajo de Fin de Master pretende dar una introducción al desarrollo actual del campo, desde los conceptos físicos que subyacen en ella, hasta el estado del arte de la tecnología. El texto esta pensado para personas con una formación base en Ingeniería de las Telecomunicaciones, y con poco o ningún conocimiento en mecánica cuántica. Sin embargo, otros lectores con formación en ingeniería o física también podrán sacar provecho de él. Tras la lectura de éste, el lector podrá tener un buen punto de partida en el campo, desde el que seguir desarrollando su trabajo.Universidad de Sevilla. Máster en Ingeniería de Telecomunicació

Optical ground receivers for satellite based quantum communications

Cryptography has always been a key technology in security, privacy and defence. From ancient Roman times, where messages were sent cyphered with simple encoding techniques, to modern times and the complex security protocols of the Internet. During the last decades, security of information has been assumed, since classical computers do not have the power to break the passwords used every day (if they are generated properly). However, in 1984, a new threat emerged when Peter Shor presented the Shor’s algorithm, an algorithm that could be used in quantum computers to break many of the secure communication protocols nowadays. Current quantum computers are still in their early stages, with not enough qubits to perform this algorithm in reasonable times. However, the threat is present, not future, since the messages that are being sent by important institutions can be stored, and decoded in the future once quantum computers are available. Quantum key distribution (QKD) is one of the solutions proposed for this threat, and the only one mathematically proven to be secure with no assumptions on the eavesdropper power. This optical technology has recently gained interest to be performed with satellite communications, the main reason being the relative ease to deploy a global network in this way. In satellite QKD, the parameter space and available technology to optimise are very big, so there is still a lot of work to be done to understand which is the optimal way to exploit this technology. This dissertation investigates one of these parameters, the encoding scheme. Most satellite QKD systems use polarisation schemes nowadays. This thesis presents for the first time an experimental work of a time-bin encoding scheme for free-space receivers within a full QKD system in the second chapter. The third and fourth chapter explore the advantages of having multi-protocol free-space receivers that can boost the interoperability between systems, polarisation filtering techniques to reduce background. Finally, the last chapter presents a new technology that can help increase communications rates

Análisis de la norma 802.11p mediante simulación

En este trabajo se analiza la norma 802.11p, desarrollada para los entornos de comunicaciones vehiculares, mediante el software de simulación NS-3. Ésta es una tecnología aún en desarrollo, y de ser exitosa, promete ofrecernos grandes mejoras en nuestra vida cotidiana. Comenzaremos con una introducción sobre el concepto en el que se basa su desarrollo, El Internet de las Cosas, posteriormente trataremos la teoría sobre la que se ha sustentado el proyecto y por último simularemos varios escenarios con el objetivo de entender el funcionamiento de éstas redes. Para finalizar, se extraerán las conclusiones principales sobre cómo funcionan las comunicaciones vehiculares y se recomendarán las posibles líneas futuras de ampliación de este trabajo.In this project we will analyze the standard 802.11p, whose development was focused on the vehicular communiactions, using the simulation software NS-3. This technology is still being developed and, given the case it becomes a success, it can potentially improve our everyday life. We will start with an introduction to the concept behind its development, the Internet of Things. Then, we will address the theory in which the building of the project is based and finally we will simulate some scenarios in order to understand how this networks work. Lastly we will collect the main conclusions about the vehicular comunications and we will suggest some posibles ways to continue in future works.Universidad de Sevilla. Grado en Ingeniería de las Tecnologías de Telecomunicació

Prevalencia y factores de riesgo asociados a infección por virus SARS-CoV-2 en trabajadores del Instituto Nacional de Salud del Niño de Perú, abril 2020 a marzo 2021

Objective: To determine the prevalence and risk factors associated with SARS-CoV-2 infection among workers of Instituto Nacional de Salud del Niño (INSN) from April 2020 to March 2021. Materials and methods: A non-experimental, descriptive, cross-sectional study. The sample consisted of 608 workers who tested positive for COVID-19 using a rapid antigen test. The COVID-19 clinical-epidemiological research sheets prepared bythe Ministry of Health of Peru and self-administered by the workers were reviewed. The INSN Department of Epidemiology staff verified the completion of the sheets. The data was entered into a database, which was used for the respective statistical analysis. The study was approved by the INSN Institutional Research Ethics Committee (registration code: PI-17/21). Results: COVID-19 prevalence among INSN workers was 7.24 % from April 2020 to March 2021. Out of the workers with COVID-19 71.4 % were women; 83.4 % were in the 30 to 59 age range with an average age of 44.71 years; 65.6 % were healthcare workers, most of whom were nursing technicians; and 56.9 % experienced symptoms, mainly fever/chills (12.2 %), cough (8.9 %), malaise (7.7 %), sore throat (6.7 %), stuffy nose (2.5 %) and headache (1.3 %). Most workers lived in Lima Centro districts (33.2 %). A significant association between sex, age groups, worker type and worker profile was found. Conclusions: COVID-19 prevalence among INSN workers was 7.24 %; the most frequent characteristics, which showed significant differences with the rest of the factors, were being a woman, healthcare worker and nursing technician. A total of 56.9 % of the workers experienced symptoms, only 20.9 % developed clinical signs and 10.9 % had comorbidities.Objetivo: Determinar la prevalencia y factores de riesgo asociados a la infección por virus SARS-CoV-2 en trabajadores del Instituto Nacional de Salud del Niño (INSN), en el periodo de abril 2020 a marzo 2021.Materiales y métodos: Estudio no experimental, descriptivo, transversal. La muestra corresponde a 608 trabajadores de salud que resultaron positivos a la prueba serológica rápida. Se revisaron las fichas de investigación clínica epidemiológica COVID-19elaboradas por el Ministerio de Salud de Perú, que fueron autoadministradas por los trabajadores de salud, y el personal de Epidemiología del INSN verificó el llenado de la ficha. Los datos se introdujeron en una base de datos que sirvió para el análisisestadístico respectivo. El estudio fue aprobado por el Comité Institucional de Ética en Investigación del INSN (código de registro: PI-17/21). Resultados: La prevalencia fue de 7,24 % de COVID-19 en trabajadores del INSN entre abril del 2020 y marzo del 2021. El 71,4 % fueron mujeres, los participantes presentaron una media de edad de 44,71 años, mayoritariamente en el rango de los 30 a 59 años(83,4 %); el 65,6 % fueron asistenciales, de los cuales la mayoría fueron técnicos en enfermería. El 56,9 % de los trabajadores presentaron síntomas, principalmente fiebre/escalofríos (12,2 %), tos (8,9 %), malestar general (7,7 %), dolor de garganta (6,7 %),congestión nasal (2,5 %) y cefalea (1,3 %) . La mayoría de trabajadores residían en los distritos de Lima . Se encontró asociación significativa por sexo y grupos de edad, tipo de trabajador y perfil del trabajador. Conclusiones: La prevalencia de COVID-19 entre los trabajadores del INSN fue del 7,24 %; las características más frecuentes que mostraron diferencias significativas con el resto de los factores fueron el ser mujer, trabajador asistencial y técnica deenfermería. El 56,9 % de los trabajadores presentó síntomas, solo el 20,9 %, signos clínicos y el 10,9 % tuvo comorbilidades

Naica's "Cueva de los Cristales": Synchrotron radiation characterization of the wall-crystal interface

Naica's "Cueva de los Cristales" was discovered in 2000. It has been considered particularly interesting for its beauty and the challenges it poses to crystallography. This article focuses on the study of the wall-selenite interface by various techniques, particularly X-ray diffraction (XRD), scanning electron microscopy (SEM), with emphasis on micro-X-ray fluorescence (micro-XRF) and micro-X-ray absorption near edge structure (micro-XANES). The main phases calcite, quartz, goethite and montmorillonite were identified by XRD, as well as the association of crystalline and amorphous minor and trace phases of Zn, Mn, Cu, As and Pb. The latter were identified in micro-XRF maps and micro-XANES spectra. The results for the morphology and the chemical description of the crystal-wall interface may contribute to propose a nucleation and growth mechanism for Naica megacrystals

Treatment with tocilizumab or corticosteroids for COVID-19 patients with hyperinflammatory state: a multicentre cohort study (SAM-COVID-19)

Objectives: The objective of this study was to estimate the association between tocilizumab or corticosteroids and the risk of intubation or death in patients with coronavirus disease 19 (COVID-19) with a hyperinflammatory state according to clinical and laboratory parameters. Methods: A cohort study was performed in 60 Spanish hospitals including 778 patients with COVID-19 and clinical and laboratory data indicative of a hyperinflammatory state. Treatment was mainly with tocilizumab, an intermediate-high dose of corticosteroids (IHDC), a pulse dose of corticosteroids (PDC), combination therapy, or no treatment. Primary outcome was intubation or death; follow-up was 21 days. Propensity score-adjusted estimations using Cox regression (logistic regression if needed) were calculated. Propensity scores were used as confounders, matching variables and for the inverse probability of treatment weights (IPTWs). Results: In all, 88, 117, 78 and 151 patients treated with tocilizumab, IHDC, PDC, and combination therapy, respectively, were compared with 344 untreated patients. The primary endpoint occurred in 10 (11.4%), 27 (23.1%), 12 (15.4%), 40 (25.6%) and 69 (21.1%), respectively. The IPTW-based hazard ratios (odds ratio for combination therapy) for the primary endpoint were 0.32 (95%CI 0.22-0.47; p < 0.001) for tocilizumab, 0.82 (0.71-1.30; p 0.82) for IHDC, 0.61 (0.43-0.86; p 0.006) for PDC, and 1.17 (0.86-1.58; p 0.30) for combination therapy. Other applications of the propensity score provided similar results, but were not significant for PDC. Tocilizumab was also associated with lower hazard of death alone in IPTW analysis (0.07; 0.02-0.17; p < 0.001). Conclusions: Tocilizumab might be useful in COVID-19 patients with a hyperinflammatory state and should be prioritized for randomized trials in this situatio