Frieze matrices and infinite frieze patterns with coefficients

Frieze patterns are combinatorial objects that are deeply related to cluster theory. Determinants of frieze patterns arise from triangular regions of the frieze, and they have been considered in previous works by Broline-Crowe-Isaacs, and by Baur-Marsh. In this article, we introduce a new type of matrix for any infinite frieze pattern. This approach allows us to give a new proof of the frieze determinant result given by Baur-Marsh.Comment: In the new version, we explain the relation of our work to the determinant result of Baur and Marsh (BM12 arXiv:1008.5329) and to the work of Holm and Jorgensen (HJ arXiv:2212.11723

Optimized LTE Data Transmission Procedures for IoT: Device Side Energy Consumption Analysis

The efficient deployment of Internet of Things (IoT) over cellular networks, such as Long Term Evolution (LTE) or the next generation 5G, entails several challenges. For massive IoT, reducing the energy consumption on the device side becomes essential. One of the main characteristics of massive IoT is small data transmissions. To improve the support of them, the 3GPP has included two novel optimizations in LTE: one of them based on the Control Plane (CP), and the other on the User Plane (UP). In this paper, we analyze the average energy consumption per data packet using these two optimizations compared to conventional LTE Service Request procedure. We propose an analytical model to calculate the energy consumption for each procedure based on a Markov chain. In the considered scenario, for large and small Inter-Arrival Times (IATs), the results of the three procedures are similar. While for medium IATs CP reduces the energy consumption per packet up to 87% due to its connection release optimization

Una nota sobre conjuntos de sidon infinitos

Un conjunto de Sidon es un subconjunto de los enteros con la propiedad que la suma de cada dos elementos es distinta. En 1998, I. Ruzsa dio una construcción probabilística de un conjunto de Sidon infinito cuya función de conteo es $x^{\sqrt{2}-1+o(1)}$. En este trabajo mostramos una simplificación de dicha construcción

Analysis of the operating parameters in a Stirling cryocooler

In this work, the results obtained in different tests performed on a Stirling cryocooler are shown, as well as a comparative analysis of these results with different load pressures. The prototype is a single-acting Stirling engine with a piston and displacer, which is used to liquefy air with helium as the working fluid; this is an integral Stirling (β-type). A three-phase asynchronous electric motor drives the Stirling engine and cooling, in the hot focus, is performed with a pressurized water circuit. In the cold focus are reached very low temperatures, around 75 K (-198 °C). The study has been developed at different load pressures of the working fluid and it shows a comparative analysis about the most important work parameters evolution. The parameters studied are the following: cooling water inlet and outlet temperatures, cold and hot focus temperatures, voltage and intensity consumed by the electric motor that drives the Stirling engine and quantity of liquid air obtained. The results show that it is very likely to use this configuration in industrial processes when they need cold and heat simultaneously.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Monitoring Muscle Stem Cell Cultures with Impedance Spectroscopy

The aim of this work is to present a new circuit for the real-time monitoring the processes of cellular growth and differentiation of skeletal myoblast cell cultures. An impedance spectroscopy Oscillation-Based technique is proposed for the test circuit, converting the biological system into a voltage oscillator, and avoiding the use of very high performance circuitry or equipment. This technique proved to be successful in the monitoring of cell cultures growth levels and could be useful for determining the degree of differentiation achieved, of practical implications in tissue engineering.Ministerio de Economía y Competitividad TEC2013-46242-C3-1-

Analytical Modeling and Experimental Validation of NB-IoT Device Energy Consumption

The recent standardization of 3GPP Narrowband Internet of Things (NB-IoT) paves the way to support low-power wide-area (LPWA) use cases in cellular networks. NB-IoT design goals are extended coverage, low power and low cost devices, and massive connections. As a new radio access technology, it is necessary to analyze the possibilities NB-IoT provides to support different traffic and coverage needs. In this paper, we propose and validate an NB-IoT energy consumption model. The analytical model is based on a Markov chain. For the validation, an experimental setup is used to measure the energy consumption of two commercial NB-IoT user equipments (UEs) connected to a base station emulator. The evaluation is done considering three test cases. The comparison of the model and measurements is done in terms of the estimated battery lifetime and the latency needed to finish the control plane procedure. The conducted evaluation shows the analytical model performs well, obtaining a maximum relative error of the battery lifetime estimation between the model and the measurements of 21% for an assumed interarrival time (IAT) of 6 min.This work was supported in part by the Spanish Ministry of Economy and Competitiveness and the European Regional Development Fund under Project TEC2016-76795-C6-4-R and in part by the H2020 European Project TRIANGLE under Grant 688712

Sistema de trasnporte, metropolis y territorio. El caso del Área Metropolitana Cordoba – R. Argentina

El análisis y planificación de la infraestructura en general y en particular la del transporte y de comunicaciones no puede considerarse de manera aislada, sino que este proceso debe ser parte de otro mayor que involucra el sistema territorial, derivado de las fuertes relaciones existentes entre el transporte y el uso del suelo a distintas escalas y por el carácter estructurante de la infraestructura sobre la organización del territorio. Se desarrolla una síntesis de la infraestructura de transporte del Área Metropolitana de Córdoba (AMCor), bajo un enfoque sistémico a partir de sus componentes más significativos considerando su marco territorial y su inserción en la escala nacional

Monitor del Comercio Internacional

The project has maintained the original objectives in terms of analysis of Argentine foreign trade and trade policy pursued by its major trading partners; the evolution of the international economy and business opportunities for Argentina exports During 2014 the analysis of the global economic and trade scenario and the impact on the Argentine export sector deepened. A review of the Prebisch-Singer theory was published in the Journal of Economics and International Trade, analyzing the terms of trade in the sector of agricultural commodities in the period 2001-2008. This study confirmed that the improvement in the terms of trade was due to international economic factorssuch as increased demand from China and India, in addition to financial speculators entering themarket of commodities, play significant roles in rising prices of these. Finally, another line ofanalysis on the potential causal effect of trade liberalization on poverty in Latin American countriesover the period 2002-2012 was incorporated. To do this, a panel data was constructed and a seriesof econometric estimates were made by fixed and random effects. The emerging results indicate anegative association between poverty and trade liberalization, however, when controlling for othercovariates, the ratio of trade liberalization improves their statistical significance and increases itsslope, this indicates that trade policies must be accompanied by other complementary policies toimprove its performance in relation to the reduction of poverty levels. Similarly, the weaknessesof the MERCOSUR bloc were investigated by analyzing the dynamics of exchange between Argentina- Brazil and the particular concentration in the automotive sector. With this work, poorconvergence around the block and assisted nature of the exchange showed.El Proyecto ha mantenido los objetivos iniciales en cuanto al análisis del comercio exterior argentino y la política comercial aplicada por sus principales socios comerciales; la evolución de la economía internacional y las oportunidades de negocios para la oferta exportable argentina. Durante el año 2014 se profundizó el análisis del escenario económico y comercial mundial y el impacto sobre el sector exportador argentino. Se publicó en la Revista de Economía y Comercio Internacional una revisión de la teoría Prebisch-Singer, en la que se analizan los términos de intercambio en el sector de commodities agrícolas en el período 2001-2008. Este estudio corroboró que la mejora en los términos de intercambio se debió a factores económicos internacionales, como el aumento de la demanda de China e India, además del ingreso de agentes financieros al mercado de commodities, influyendo en el aumento de los precios de estos. Finalmente, se incorporó otra línea de análisis sobre el potencial efecto causal de la apertura comercial en la pobreza en países latinoamericanos en el período 2002-2012. Se construyó un panel de datos y se realizaron una serie de estimaciones econométricas por medio de efectos fijos y aleatorios. Resultados preliminares indican que existe una asociación negativa entre la pobreza y la apertura comercial, sin embargo, cuando se controla por distintas covariables, el coeficiente de apertura comercial mejora su significación estadística y aumenta su pendiente; esto indica que las políticas comerciales deben ser acompañadas por otro tipo de políticas complementarias para mejorar sus resultados en relación con la reducción de los niveles de pobreza. Asimismo, se investigaron las debilidades del bloque MERCOSUR, analizando la dinámica de intercambio entre Argentina - Brasil y la particular concentración en el sector automotriz. Con este trabajo, se mostraron las deficiencias en la convergencia en todo el bloque y el carácter asistido del intercambio