MAPS OF CONTINUOUS SPATIAL DEPENDENCE

Heterogeneity is one of the distinguishing features in spatial econometric models. It is a frequent problem in applied work and can be very damaging for statistical inference. In this paper, we focus on the problems implied by the existence of instabilities in the mechanism of spatial dependence in a spatial lag model, assuming that the other terms of the specification remain stable. We begin the discussion with the role played by the algorithms of local estimation in detecting the instabilities. Problems appear when one must decide what to do once the existence of heterogeneity has been confirmed. The logical reaction is trying to parameterize this lack of stability. However, the solution is not obvious. Assuming that a set of indicators related to the problem has been identified, we propose a simple technique to deal with the unknown functional form. In the final part of the paper, we present some Monte Carlo evidence and an application to evaluate the instability in the mechanisms of spatial dependence in the convergence process of the European Regions.DEPENDENCE, LOCAL ESTIMATION, MONTE-CARLO, SPATIAL INSTABILITY

Spatial SUR models: Specification, Testing and Selection

Our paper focuses on the case of SUR models with spatial effects. Specifically, the problem that we pose is testing for the presence of spatial effects in these multivariate models, considering that one of our main interests is to deal with the question of selecting the most adequate specification for the data. In order to do this, we obtain several tests that check for the fundamental hypothesis of the model, including the assumption of time stability of the spatial dependence mechanisms. We solve the discussion in a maximum-likelihood framework because this facilitates the obtaining of appropriate tests. The second part of the paper contains a Monte Carlo experiment in order to study the behaviour of the two most popular model selection strategies, Specific-to- General or General-to-Specific, using the collection of tests that have been proposed.This work has been carried out with the financial support of project ECO2009-10534/ECON of the Ministerio de Ciencia y Tecnología of the Reino de España

spsur: An R Package for Dealing with Spatial Seemingly Unrelated Regression Models

Spatial seemingly unrelated regression (spatial SUR) models are a useful multiequational econometric specification to simultaneously incorporate spatial effects and correlated error terms across equations. The purpose of the spsur R package is to supply a complete set of functions to test for spatial structures in the residual of a SUR model; to estimate the most popular specifications by applying different methods and test for linear restrictions on the parameters. The package also facilitates the estimation of socalled spatial impacts, conveniently adapted to a SUR framework. The package includes functions to simulate datasets with the features decided by the user, which may be useful in teaching activities or in more general research projects. The article concludes with a real data application showing the potential that spsur has to examine the relation of individual mobility over geographic areas and the incidence of COVID-19 in Spain during the first lockdown

Disentangling a and ß relaxation in orientationally disordered crystals with theory and experiments

We use a microscopically motivated Generalized Langevin Equation (GLE) approach to link the vibrational density of states (VDOS) to the dielectric response of orientational glasses (OGs). The dielectric function calculated based on the GLE is compared with experimental data for the paradigmatic case of two OGs: Freon 112 and Freon 113, around and just above Tg. The memory function is related to the integral of the VDOS times a spectral coupling function Y(¿p), which tells the degree of dynamical coupling between molecular degrees of freedom at different eigenfrequencies. The comparative analysis of the two Freons reveals that the appearance of a secondary ß relaxation in Freon 112 is due to cooperative dynamical coupling in the regime of mesoscopic motions caused by stronger anharmonicity (absent in Freon 113), and is associated with comparatively lower boson peak in the VDOS. The proposed framework brings together all the key aspects of glassy physics (VDOS with boson peak, dynamical heterogeneity, dissipation, anharmonicity) into a single model.Peer ReviewedPostprint (published version

Fiscalidad habitual de las pymes antes y después de la Reforma Tributaria de 2015. Un análisis tributario y económico aplicado a un negocio de "carpintería metálica"

El objeto de este trabajo es dar una idea lo más precisa posible, de los factores fiscales que inciden en el ciclo económico anual de una pequeña empresa, analizando de forma particular, la incidencia para la empresa y empresario de la nueva Reforma Fiscal que ha entrado en vigor en 2015. En primer lugar, se da una visión global del proceso de constitución de la sociedad y las figuras tributarias que le afectan a partir de entonces: constitución, Impuesto sobre Actividades Económicas, contratación de personal, suministros y licencias, declaraciones anuales informativas, además de los impuestos anuales con mayor relevancia, es decir, Impuesto sobre el Valor Añadido, Sociedades o el Impuesto sobre la Renta de las Personas Físicas. Con posterioridad, en el apartado de conclusiones, se valora si la nueva reforma es beneficiosa o no, para la empresa y empresario desde el punto de vista de los principios generales de la imposición óptima, es decir desde la equidad, la eficiencia y la sencillez. Finalmente se adjunta un apartado final denominado anexos, donde se incluyen todos los formularios e impresos que han sido necesarios para la elaboración del trabajo, y que supone una buena fuente de recopilación y presentación de los resultados obtenidos

Evaluation of the spatial patterns and risk factors, including backyard pigs, for classical swine fever occurrence in Bulgaria using a Bayesian model

The spatial pattern and epidemiology of backyard pig farming and other low bio-security pig production systems and their role in the occurrence of classical swine fever (CSF) is described and evaluated. A spatial Bayesian model was used to explore the risk factors, including human demographics, socioeconomic and environmental factors. The analyses were performed for Bulgaria, which has a large number of backyard farms (96% of all pig farms in the country are classified as backyard farms), and it is one of the countries for which both backyard pig and farm counts were available. Results reveal that the high-risk areas are typically concentrated in areas with small family farms, high numbers of outgoing pig shipments and low levels of personal consumption (i.e. economically deprived areas). Identification of risk factors and high-risk areas for CSF will allow to targeting risk-based surveillance strategies leading to prevention, control and, ultimately, elimination of the disease in Bulgaria and other countries with similar socio-epidemiological condition

Effects of long-term vaccination against Coxiella burnetii on the fertility of high-producing dairy cows

The impact of long-term vaccination against Coxiella burnetii on the fertility of cows was studied. Double vaccinations three weeks apart at the start of the third trimester of gestation in each of two consecutive pregnancies were applied. The final study population consisted of 410 cows after the first vaccination round. Based on the odds ratios, the likelihood of early fetal loss (pregnancy loss following a positive pregnancy diagnosis before Day 90 of gestation) was higher in control cows (OR = 1.42) than in vaccinated cows. The final study population consisted of 336 cows after the second round of vaccination. According to the odds ratios, vaccinated C. burnetii seronegative cows were less likely to be subfertile (> 3 AI) (OR = 0.4) compared to non-vaccinated seronegative animals, and the likelihood of early fetal loss was lower in vaccinated C. burnetii seropositive animals (OR = 0.3) compared to non-vaccinated seronegative cows. Seropositivity to C. burnetii was positively related to twin pregnancy after the two rounds of vaccination (OR = 2.1 and 3.5, respectively). These results indicate that two consecutive vaccination rounds against C. burnetii in advanced gestation reduce subfertility and early fetal loss in dairy cows

Low-Temperature Heat Capacity Anomalies in Ordered and Disordered Phases of Normal and Deuterated Thiophene

We measured the specific heat Cp of normal (C4H4S) and deuterated (C4D4S) thiophene in the temperature interval of 1 = T, K = 25. C4H4S exhibits a metastable phase II2 and a stable phase V, both with frozen orientational disorder (OD), whereas C4D4S exhibits a metastable phase II2, which is analogous to the OD phase II2 of C4H4S and a fully ordered stable phase V. Our measurements demonstrate the existence of a large bump in the heat capacity of both stable and metastable C4D4S and C4H4S phases at temperatures of ~10 K, which significantly departs from the expected Debye temperature behavior of Cp ˜ T3. This case study demonstrates that the identified low-temperature Cp anomaly, typically referred to as a “Boson-peak” in the context of glassy crystals, is not exclusive of disordered materials.Peer ReviewedPostprint (published version