476 research outputs found
EMU and macroeconomic shocks: some evidence on Spanish regions
According to the Theory of Optimal Currency Areas, one of the main costs that EMU may entail for countries and regions belonging in it is the loss of monetary autonomy at the country level. In fact, the scenario brought about by the single currency does not allow for domestic policy adjustments (i.e a change in the exchange rate or a specific monetary measure) in response to shocks. The importance of this cost, in turn, is related to the nature of shocks impinging over the different countries and regions that encompass the eurozone. If the probability that countries and regions suffer the same sort of shock is large, then a common policy designed by the ECB will have beneficial effects on the whole eurozone. Instead, if regions or countries are likely to be exposed to different kinds of shocks, then the common monetary policy will benefit some areas in detriment of others. To address this issue empirically, this paper focuses in the analysis of the shocks that have hit the Spanish regions in the recent past. In particular, we want to identify the kind of shocks that have been suffered by the Spanish regions in the last decades, distinguishing several categories: symmetric versus asymmetric, persistent versus transitory and demand shocks versus supply shocks. By symmetric shocks we understand those that have similar impact on all regions. Permanent shocks are those characterised by side effects that do not vanish in the short run. An example of a demand shock is a change in consumers' preferences, whereas a supply shock is typically a modification in the price of a raw material. We examine the behaviour of GAV and prices for 17 Spanish regions over the period 1955-97. In particular, we write a baseline model in the form of the state-of-spaces, in order to be able to apply the Kalman filter. Main conclusions are as follows: first, and employing the assumption that common shocks are tantamount to symmetric shocks, it seems that, in most cases, the shocks that have affected the Spanish regions have been mostly symmetric, while asymmetric shocks have been more sparse. Second, empirical results suggest that the effects of these shocks have been, generally speaking, persistent rather than transitory. Finally, the estimation suggests that supply shocks have been slightly more frequent that demand shocks. The policy implications of these results are that the lack of monetary autonomy and the loss of the exchange rate as adjustment mechanisms may not be very onerous. The common monetary policy implemented by the ECB will probably have similar effects on all Spanish regions. Therefore, the danger of an increase in regional disparities via this channel do not seem to be very severe.
The 1D Hubbard model within the Composite Operator Method
Although effective for two dimensional (2D) systems, some approximations may
fail in describing the properties of one-dimensional (1D) models, which belong
to a different universality class. In this paper, we analyze the adequacy of
the Composite Operator Method (COM), which provides a good description of many
features of 2D strongly correlated systems, in grasping the physics of 1D
models. To this purpose, the 1D Hubbard model is studied within the framework
of the COM by considering a two-pole approximation and a paramagnetic ground
state. The local, thermodynamic and single-particle properties, the correlation
functions and susceptibilities are calculated in the case of half filling and
arbitrary filling. The results are compared with those obtained by the Bethe
Ansatz (BA) as well as by other numerical and analytical techniques. The
advantages and limitations of the method are analyzed in detail.Comment: 19 RevTeX pages, 41 embedded eps figure
Conciencia y Realidad en la Obra de Arte
Conciencia y Realidad en la Obra de Art
Cohesive framework for non-line-of-sight imaging based on Dirac notation
The non-line-of-sight (NLOS) imaging field encompasses both experimental and computational frameworks that focus on imaging elements that are out of the direct line-of-sight, for example, imaging elements that are around a corner. Current NLOS imaging methods offer a compromise between accuracy and reconstruction time as experimental setups have become more reliable, faster, and more accurate. However, all these imaging methods implement different assumptions and light transport models that are only valid under particular circumstances. This paper lays down the foundation for a cohesive theoretical framework which provides insights about the limitations and virtues of existing approaches in a rigorous mathematical manner. In particular, we adopt Dirac notation and concepts borrowed from quantum mechanics to define a set of simple equations that enable: i) the derivation of other NLOS imaging methods from such single equation (we provide examples of the three most used frameworks in NLOS imaging: back-propagation, phasor fields, and f-k migration); ii) the demonstration that the Rayleigh-Sommerfeld diffraction operator is the propagation operator for wave-based imaging methods; and iii) the demonstration that back-propagation and wave-based imaging formulations are equivalent since, as we show, propagation operators are unitary. We expect that our proposed framework will deepen our understanding of the NLOS field and expand its utility in practical cases by providing a cohesive intuition on how to image complex NLOS scenes independently of the underlying reconstruction method
Calidad del servicio de agua potable y su relación con la satisfacción en usuarios domésticos del distrito de Imperial, 2021
El objetivo principal de la presente investigación fue determinar si existe
relación entre la calidad del servicio de agua potable y la satisfacción en los
usuarios domésticos del Distrito de Imperial, Cañete, 2021, para ello, se ha
aplicado un tipo de investigación con enfoque cuantitativo de tipo descriptivo
explicativo y aplicada con un diseño no experimental transversal correlacional
entre las variables. La muestra estuvo conformada por un total de 137 usuarios
domésticos obtenidas a través de un muestreo aleatorio y estratificado aplicados
a una población total de 7 943 usuarios domésticos del Distrito de Imperial, a
quienes se aplicaron dos cuestionarios con respecto a la calidad del servicio y
satisfacción en usuarios los cuales contenían 24 y 20 preguntas cerradas
respectivamente. Los resultados obtenidos permiten concluir que, existe relación
directa y significativa entre ambas variables puesto que se obtuvo un valor de
0.813 del índice de Correlación de Pearson con una relación de significancia de
0.00, el cual es menor el valor de la estadística de referencia el cual es de 0.01,
por lo que se puede determinar que hay una gestión aceptable en la prestación
del servicio de agua potable brindada por la empresa prestadora y que genera
una buena percepción entre sus usuarios domésticos en el distrito de Imperial,
Cañete
Gestión por competencias y motivación en el servicio de voluntarios en una iglesia evangélica, Ilo, 2023
En las vivencias de iglesia y de su gestionamiento se presentan situaciones
que implican poder evaluar la forma cómo se viene realizando el trabajo específico
de anunciar el Evangelio y formar comunidad; por eso, el objetivo general fue
determinar la relación entre la gestión por competencias y la motivación en el
servicio de voluntarios en una iglesia evangélica, Ilo, 2023. En el aspecto
metodológico fue un estudio aplicado, cuantitativo y con diseño descriptivo
correlacional; contó con una población muestral conformada por 45 fieles
voluntarios, a ellos se les aplicaron dos cuestionarios, uno por variable, que fueron
preparados por el investigador y que fueron sometidos a confiabilidad, por Alfa de
Cronbach, y a validez por juicio de expertos. La contrastación de las hipótesis se
realizó aplicando el Rho de Spearman. Con la sistematización de los resultados se
arribó a la conclusión de que existe una relación significativa y directa entre la
gestión por competencias y la motivación en el servicio de voluntarios de una iglesia
evangélica, Ilo, 2023; esto está respaldado por la aplicación del Rho de Spearman
cuyo coeficiente fue de 0,486 y una p<0,01, por lo que se rechazó la hipótesis nula
y se aceptó la hipótesis alternativa
Auto-tooling to Bridge the Concrete and Abstract Syntax of Complex Textual Modeling Languages
This thesis contributes to improving support for complex textual modeling languages. This support refers to the automatic generation of tools for the end user -- e.g. parsers, editors, views, etc. -- and (parts of) the standard specifications defined to describe the languages -- e.g. the Object Management Group open specifications for varied modeling languages.
The particular subset of languages considered in the thesis are textual, model-based and complex. They are considered textual when their concrete syntax is textual, in particular, defined by a grammar. They are considered model-based when their abstract syntax is defined by a meta-model. They are considered complex when there is a significant gap between the concrete and abstract syntax of the language; in other words, when the abstract syntax meta-model cannot directly be derived or inferred from the concrete syntax grammar.
The contributions of this thesis address the problem of bridging the concrete and abstract syntax of complex textual modeling languages. In particular, the contributions include (a) a gap analysis of the limitations of related work; (b) a domain-specific transformation language for defining and executing concrete syntax to abstract syntax bridges; (c) an experimental evaluation of the proposed solution including studies to compare with related work.
Existing related work presents different issues when working on complex textual modeling languages. Either sufficient automatic tooling generation is not provided (Gra2Mol), or model-based languages are not appropriately supported (Spoofax), or complex gaps between the concrete and abstract syntax cannot be bridged (Xtext).
This thesis identifies the different concerns that arise when bridging the concrete and abstract syntax of complex textual modeling languages. In addition, some limitations of relevant related work are shown. With the aim of addressing these identified concerns a new approach is proposed, showing how these concerns are particularly addressed. Specifically, the proposed approach consists of complementing relevant related work (Xtext) with a novel domain-specific transformation language to declare bridges between the concrete syntax and abstract syntax of complex textual modeling languages.
The domain-specific transformation language is the main contribution of this thesis and is evaluated by means of qualitative and quantitative studies. Subject to the presented examples, the conducted experiments show that the proposed approach brings measurable benefits -- in terms of size of specification artefacts and execution time of the underlying implementation -- when compared to the state-of-the-art
VELOXDFS: ELASTIC BLOCKS IN DISTRIBUTED FILE SYSTEMS FOR BIG DATA FRAMEWORKS
Department of Computer Science and EngineeringBig data processing and storage has grown into one of the most important aspects of distributed
computing in the last years. Much of the effort in this area goes into sophisticated algorithms and
architectures which provides a small leap to a more efficient big data system. This works explores a
novel idea in which by modifying a simple component found in most of the distributed systems it leads
to a significant improvement of the overall performance of the underline system which is often blind to
this modification. This small component is file partitioning, and it plays a crucial role in the division of
the workload for a distributed job into small working units.
This work proposes a different view of file partitioning which separates partitions of a file into
conventional simple blocks to a more sophisticated system in which those blocks can change its size at
running time and consequently been able to adjust the amount of input of each of the working units in
the distributed job. The implications that this technique unleashes are enormous since it can be virtually
plugged to any distributed system and improve its system utilization and performance. In this research
we plug our proposed file partitioning system in one the most used data processing system of our time,
Apache Hadoop.
Coincidentally, this thesis also presents a novel distributed file system named VeloxDFS which im-
plements elastic blocks among other remarkable features and can be used as a substitute of the Apache
Hadoop Distributed File System.clos
Evolution in Islands: contrasting morph frequencies in damselfly populations of the Balearic Islands
Colour polymorphism is an example of visible phenotypic variability that is often associated with ecological factors and may produce local adaptations. Small populations, particularly in islands, offer opportunities for evolutionary novelties, and are therefore of particular interest to the study of polymorphisms. Here we study the dynamics of female colour morphs in the damselfly Ischnura elegans in the Balearic Islands. We found that insular populations are small, show low density, low mating activity, and low androchrome frequency. Our surveys suggest that male harassment is a powerful force in the dynamics of this female-limited polymorphism, because high male densities result in lower presence of mature females around the water, where copulation takes place. Non-male-like (infuscans) females have higher mating frequency. Androchromes were rare (15%) in all populations, but the frequency of the two non-male like females (infuscans and aurantiaca) was reversed between islands, despite their geographical proximity. We found a possible novel morph, suggesting that insular conditions allow innovations. Fitness differences between the two non-male-like females of I. elegans are still understudied, because most previous research has concentrated on the maintenance of androchromes, and are therefore a priority for future research.Agencia Estatal de Investigación | Ref. PGC2018-096656-B-I00Universidade de Vigo/CISU
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