Optimal monetary policy in a model of money and credit

The authors investigate the extent to which monetary policy can enhance the functioning of the private credit system. Specifically, they characterize the optimal return on money in the presence of credit arrangements. There is a dual role for credit: It allows buyers to trade without fiat money and also permits them to borrow against future income. However, not all traders have access to credit. As a result, there is a social role for fiat money because it allows agents to self-insure against the risk of not being able to use credit in some transactions. The authors consider a (nonlinear) monetary mechanism that is designed to enhance the credit system. An active monetary policy is sufficient for relaxing credit constraints. Finally, they characterize the optimal monetary policy and show that it necessarily entails a positive inflation rate, which is required to induce cooperation in the credit system.Monetary policy ; Money ; Credit

Optimal monetary policy in a model of money and credit

The authors study optimal monetary policy in a model in which fiat money and private debt coexist as a means of payment. The credit system is endogenous and allows buyers to relax their cash constraints. However, it is costly for agents to publicly report their trades, which is necessary for the enforcement of private liabilities. If it is too costly for the government to obtain information regarding private transactions, then it relies on the public information generated by the private credit system. If not all private transactions are publicly reported, the government has imperfect public information to implement monetary policy. In this case, the authors show that there is no incentive-feasible policy that can implement the socially efficient allocation. Finally, they characterize the optimal policy for an economy with a low record-keeping cost and a large number of public transactions, which results in a positive long-run inflation rate.Monetary policy ; Disclosure of information

Extended Galilean symmetries of non-relativistic strings

We consider two non-relativistic strings and their Galilean symmetries. These strings are obtained as the two possible non-relativistic (NR) limits of a relativistic string. One of them is non-vibrating and represents a continuum of non-relativistic massless particles, and the other one is a non-relativistic vibrating string. For both cases we write the generator of the most general point transformation and impose the condition of Noether symmetry. As a result we obtain two sets of non-relativistic Killing equations for the vector fields that generate the symmetry transformations. Solving these equations shows that NR strings exhibit two extended, infinite dimensional space-time symmetries which contain, as a subset, the Galilean symmetries. For each case, we compute the associated conserved charges and discuss the existence of non-central extensions.Postprint (author's final draft

Control of multi-terminal HVDC networks towards wind power integration: A review

© 2015 Elsevier Ltd. More interconnections among countries and synchronous areas are foreseen in order to fulfil the EU 2050 target on the renewable generation share. One proposal to accomplish this challenging objective is the development of the so-called European SuperGrid. Multi-terminal HVDC networks are emerging as the most promising technologies to develop such a concept. Moreover, multi-terminal HVDC grids are based on highly controllable devices, which may allow not only transmitting power, but also supporting the AC grids to ensure a secure and stable operation. This paper aims to present an overview of different control schemes for multi-terminal HVDC grids, including the control of the power converters and the controls for power sharing and the provision of ancillary services. This paper also analyses the proposed modifications of the existing control schemes to manage high participation shares of wind power generation in multi-terminal grids.Postprint (author's final draft

Heart rate differences between symptomatic and asymptomatic Brugada syndrome patients at night

Peer ReviewedPostprint (author's final draft

Análisis del ECG para la detección automática del patrón característico del síndrome de Brugada

El síndrome de Brugada es una enfermedad hereditaria caracterizada por un patrón electrocardiográfico característico, así como por un aumento del riesgo de sufrir arritmias cardíacas y muerte súbita. No existen actualmente indicadores objetivos que permitan determinar el riesgo individual, por lo que la elegibilidad para la implantación de desfibriladores automáticos implantables con el fin de prevenir eventos de muerte súbita genera todavía gran controversia. Dado que el electrocardiograma (ECG) proporciona información cardíaca de forma no invasiva, se presenta un algoritmo automático capaz de detectar parámetros electrocardiográficos relevantes en la enfermedad. De este modo, futuros estudios que incluyan grandes series de pacientes permitirán determinar el valor pronóstico de las diferentes variables detectadas. El algoritmo integra funciones disponibles previamente desarrolladas para la lectura y delineación de señales ECG y propone una expansión centrada en la detección de parámetros como la carga de latidos con patrón de Brugada, elevación del segmento ST, duración del segmento ST y de los intervalos PR, QRS y QTc, la variabilidad del ritmo cardíaco (VRC), la alternancia de la onda T o la carga de extrasístoles ventriculares, entre otros. El código se testeó en registros ECG continuos de 12 derivaciones y 24 horas de duración de dos pacientes con diferentes grados de severidad y un caso control, obteniendo tendencias relacionadas con la VRC y la carga de latidos con patrón de Brugada. Asimismo, se analizaron diferentes colocaciones de los electrodos con el objetivo de concluir la configuración más sensible para la detección del patrón característico.Postprint (published version

La primera feria autosostenible con anilla energética autónoma

El 2 y 3 de noviembre del 2019 tuvo lugar en Barcelona la novena edición de la feria de la movilidad eléctrica, Expoelectric. Esta feria es una iniciativa pionera que acerca el vehículo eléctrico de cero emisiones y las energías renovables a la ciudadanía a través de un conjunto de actividades lúdicas y divulgativas para impulsar la movilidad eléctrica y la transición energéticaPostprint (published version

Instability and Degeneracy in the BMN Correspondence

Non-degenerate perturbation theory, which was used to calculate the scale dimension of operators on the gauge theory side of the correspondence, breaks down when effects of triple trace operators are included. We interpret this as an instability of excited single-string states in the dual string theory for decay into the continuum of degenerate 3-string states. We apply time-dependent perturbation theory to calculate the decay widths from gauge theory. These widths are new gauge theory data which can be compared with future calculations in light cone string field theory.Comment: 23 pages, no figure

Gestor d'avaluació online

Aquesta memòria tracta sobre el desenvolupament d'una aplicació web, amb tecnologia Ajax, per la gestió d'avaluacions de manera online. L'aplicació està destinada a facilitar la creació i correcció de proves i lliuraments per part dels usuaris professors i per automatitzar el procés de realització d'una prova i lliurament per part de l'alumne.Esta memoria trata sobre el desarrollo de una aplicación web, con tecnología Ajax, para la gestión de evaluaciones de manera online. La aplicación esta destinada a facilitar la creación y corrección de pruebas y entregas por parte de los usuarios profesores y para automatizar el proceso de realización de una prueba y entrega por parte del alumno.This report explains the development of a web application, with Ajax technology, for the management of online evaluations. This application is destined to facilitate the creation and alteration of tests and deliveries by the user's teachers and to automate the process of accomplishment test and delivery for the pupil.Nota: Aquest document conté originàriament altre material i/o programari només consultable a la Biblioteca de Ciència i Tecnologia

Gravity duals of 2d supersymmetric gauge theories

We find new supergravity solutions generated by D5-branes wrapping a four-cycle and preserving four and two supersymmetries. We first consider the configuration in which the fivebranes wrap a four-cycle in a Calabi-Yau threefold, which preserves four supersymmetries and is a gravity dual to the Coulomb branch of two-dimensional gauge theories with N=(2,2) supersymmetry. We also study the case of fivebranes wrapping a co-associative four-cycle in a manifold of G_2-holonomy, which provides a gravity dual of N=(1,1) supersymmetric Yang-Mills theory in two dimensions. We also discuss the addition of unquenched fundamental matter fields to these backgrounds and find the corresponding gravity solutions with flavor brane sources.Comment: 34 pages + appendices; v2: minor improvement