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The COVID-19 outbreak was a major event that greatly impacted the economy and the health systems around the world. Understanding the behavior of the virus and being able to perform long-term and short-term future predictions of the daily new cases is a working field for machine learning methods and mathematical models. This paper compares Verhulst's, Gompertz´s, and SIR models from the point of view of their efficiency to describe the behavior of COVID-19 in Spain. These mathematical models are used to predict the future of the pandemic by first solving the corresponding inverse problems to identify the model parameters in each wave separately, using as observed data the daily cases in the past. The posterior distributions of the model parameters are then inferred via the Metropolis–Hastings algorithm, comparing the robustness of each prediction model and making different representations to visualize the results obtained concerning the posterior distribution of the model parameters and their predictions. The knowledge acquired is used to perform predictions about the evolution of both the daily number of infected cases and the total number of cases during each wave. As a main conclusion, predictive models are incomplete without a corresponding uncertainty analysis of the corresponding inverse problem. The invariance of the output (posterior prediction) with respect to the forward predictive model that is used shows that the methodology shown in this paper can be used to adopt decisions in real practice (public health). [ABSTRACT FROM AUTHOR]

A new mathematical model of Coronavirus (2019-nCov) using piecewise hybrid fractional order derivatives is given in this paper. Moreover, in order to be consistent with the physical model problem, a new parameter μ is presented. The boundedness, existence, and positivity of the solutions for the proposed model are discussed. Two improved numerical methods are presented in this paper. The Caputo proportional constant nonstandard modified Euler–Maruyama method is introduced to study the fractional stochastic model, and the Grünwald–Letnikov nonstandard finite difference method is presented to study the hybrid fractional order deterministic model. Comparative studies with real data from Spain and Wuhan are presented. [ABSTRACT FROM AUTHOR]

Gravity models have been one of the mathematical models of choice for trip distribution modeling efforts during many decades. Their simplicity offset their drawbacks, as they usually provide a reasonably good rationale for how goods are distributed in a transportation network with relatively little information. These gravity models, however, rely on the definition of a deterrence function that acts as a counterweight of the levels of supply and demand. This function is usually picked from a series of off-the-shelf available functions that only depend on a handful of parameters that need to be calibrated. Because of the limited off-the shelf options, gravity models lack flexibility in some occasions. In this paper, we tackle the use of sparse regression techniques that can accommodate data more flexibly with a reduced number of terms. Using interregional freight origin–destination data from Spain, we test two alternatives, namely, best subset regression and lasso regression. We show that the first one performs better in finding parsimonious deterrence functions and we attain gravity models that fit the data up to 14.5% better than classical deterrence functions. [ABSTRACT FROM AUTHOR]

Mathematical models have wide applications in studying COVID-19 epidemic transmission dynamics, however, most mathematical models do not take into account the heterogeneity of susceptible populations and the non-exponential distribution infectious period. This paper attempts to investigate whether non-exponentially distributed infectious period can better characterize the transmission process in heterogeneous susceptible populations and how it impacts the control strategies. For this purpose, we establish two COVID-19 epidemic models with heterogeneous susceptible populations based on different assumptions for infectious period: the first one is an exponential distribution model (EDM), and the other one is a gamma distribution model (GDM); explicit formula of peak time of the EDM is presented via our analytical approach. By data fitting with the COVID-19 (Omicron) epidemic in Spain and Norway, it seems that Spain is more suitable for EDM while Norway is more suitable for GDM. Finally, we use EDM and GDM to evaluate the impaction of control strategies such as reduction of transmission rates, and increase of primary course rate (PCR) and booster dose rate (BDR). [ABSTRACT FROM AUTHOR]

The construction of double-curvature arch dams is an attractive solution from an economic viewpoint due to the reduced volume of concrete necessary for their construction as compared to conventional gravity dams. Due to their complex geometry, many criteria have arisen for their design. However, the most widespread methods are based on recommendations of traditional technical documents without taking into account the possibilities of computer-aided design. In this paper, an innovative software tool to design FEM models of double-curvature arch dams is presented. Several capabilities are allowed: simplified geometry creation (interesting for academic purposes), preliminary geometrical design, high-detailed model construction, and stochastic calculation performance (introducing uncertainty associated with material properties and other parameters). This paper specially focuses on geometrical issues describing the functionalities of the tool and the fundamentals of the design procedure with regard to the following aspects: topography, reference cylinder, excavation depth, crown cantilever thickness and curvature, horizontal arch curvature, excavation and concrete mass volume, and additional elements such as joints or spillways. Examples of application on two Spanish dams are presented and the results obtained analyzed. [ABSTRACT FROM AUTHOR]

The paper presents an integrated approach aimed at assessing the seismic safety of Mallorca cathedral. This cathedral is an extraordinary historical construction dating back to the middle-ages. The experimental modal parameters of the cathedral were identified using Ambient Vibration Testing (AVT). The cathedral numerical model was updated using the identified modal parameters. This updated model was then used to study the seismic response of the cathedral using non-linear static (pushover) analysis. A sensitively analysis was carried out to reveal the dependency of the seismic capacity on the input materials properties. To assess the seismic performance and the safety of the cathedral, the N2 method was employed. It was found that the cathedral is safe when subjected to the earthquakes expected in Mallorca Island. [ABSTRACT FROM AUTHOR]

The Spanish residential building stock built between 1940 and 1980 period presents a high energy saving potential as it represents a significant percentage of the total housing stock and it was built without any regulation regarding energy efficiency. Accordingly, the first aim of this paper was to quantify the energy saving potential and the related reduction in CO 2 emissions of the housing stock in those years. The work focuses on the Mediterranean climate of the Comunitat Valenciana Region, therefore the energy efficiency strategies proposed are passive and deal with the envelope of buildings. On the basis of the results obtained, several scenarios with intervention periods of 10, 20 and 30 years were calculated. The conclusion was that with the current rate of annual building renovation, it will be nearly impossible to reach the goals established by the EPBD. Only a deep transformation of the building fabric within this sector could help in achieving them. Finally, it should be noted that the proposed methodology can be applied to other areas with different climates, particularly in Spain. [ABSTRACT FROM AUTHOR]

The fact that women are abused by their male partner is something that happens worldwide in the 21st century. In numerous cases, abuse only becomes publicly known when a fatal event occurs and is beyond any possible remedy, that is, when men murder their female partner. Since 2003, 793 (September 4, 2015) women have been assassinated by their significant other or excouple in Spain. Only 7.2% of murdered women had reported their fear and previous intimate partner violence (IPV) to the police. Even when the number of female victims is comparable to the number of victims by terrorism, the Government has not assigned an equal amount of resources to diminish the magnitude of this hidden social problem. In this paper, a mathematical epidemiological model to forecast intimate partner violence in Spain is constructed. Both psychological and physical aggressor subpopulations are predicted and simulated. The model’s robustness versus uncertain parameters is studied by a sensitivity analysis. [ABSTRACT FROM AUTHOR]

Background: When patients are admitted to an intensive care unit (ICU) their risk of getting an infection will be highly depend on the length of stay at-risk in the ICU. In addition, risk of infection is likely to vary over calendar time as a result of fluctuations in the prevalence of the pathogen on the ward. Hence risk of infection is expected to depend on two time scales (time in ICU and calendar time) as well as competing events (discharge or death) and their spatial location. The purpose of this paper is to develop and apply appropriate statistical models for the risk of ICU-acquired infection accounting for multiple time scales, competing risks and the spatial clustering of the data.Methods: A multi-center data base from a Spanish surveillance network was used to study the occurrence of an infection due to Methicillin-resistant Staphylococcus aureus (MRSA). The analysis included 84,843 patient admissions between January 2006 and December 2011 from 81 ICUs. Stratified Cox models were used to study multiple time scales while accounting for spatial clustering of the data (patients within ICUs) and for death or discharge as competing events for MRSA infection.Results: Both time scales, time in ICU and calendar time, are highly associated with the MRSA hazard rate and cumulative risk. When using only one basic time scale, the interpretation and magnitude of several patient-individual risk factors differed. Risk factors concerning the severity of illness were more pronounced when using only calendar time. These differences disappeared when using both time scales simultaneously.Conclusions: The time-dependent dynamics of infections is complex and should be studied with models allowing for multiple time scales. For patient individual risk-factors we recommend stratified Cox regression models for competing events with ICU time as the basic time scale and calendar time as a covariate. The inclusion of calendar time and stratification by ICU allow to indirectly account for ICU-level effects such as local outbreaks or prevention interventions. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents an evolutionary algorithm for wind speed reconstruction from synoptic pressure patterns. The algorithm operates in a search space formed by grids of pressure measures, and must classify the different situations into classes, in such a way that a measure of wind speed in a given point is minimized among patterns assigned to the same class. Then, each class is assigned a mean wind speed and direction, so the wind speed reconstruction is possible for a new grid of synoptic pressures. In this paper we present the problem model and the specific description of the evolutionary algorithm proposed to solve the problem. We also show the good performance of the proposed method in the reconstruction of the average wind speed in six wind towers in Spain. The proposed method is applicable to wind speed reconstruction or reconstruction of wind missing data of wind series, specially when there is no other variable or related measure available. [Copyright &y& Elsevier]

Abstract: In this paper the inventory of 90Sr in 34 points distributed along the Spanish peninsular territory is presented. Obtained values range between 173 Bq/m2 and 2047 Bq/m2. From these data set and those 137Cs data obtained in a previous work the 137Cs/90Sr activity ratio has been established, laying this value between 0.9 and 3.6. Also the migration depth of both radionuclides has been analysed obtaining for 137Cs an average value 57% lower than that obtained for 90Sr. Additionally, this paper presents the results obtained in 11 sampling points in which the activity vertical profile has been measured. These profiles have been analysed to state the behaviour of strontium in soils and after, by using a convective–diffusive model, the parameters of the model which governs the vertical migration of 90Sr in the soil, v (apparent convection velocity) and D (apparent diffusion coefficient) have been evaluated. Mean values obtained are 0.20 cm/year and 3.67 cm2/year, respectively. [Copyright &y& Elsevier]

This paper introduces a new assessment method classification, in which a third procedure, mixed valuation, is jointly included with the traditional economic and non-economic methodologies. The paper considers a case of multiple actors (from a previous work by the same authors-Aznar et al. (Estudios de Economía Aplicada, 25(2):389-409, ), in which a new technique for multicriteria agriculture valuation (MAVAM) was proposed. The method is specifically designed for situations in which scarce information about the elements being compared (quantified or not) is available. It works in individual and group decision making contexts and attempts to both obtain and incorporate the objective information associated with the tangible aspects of the problem and the subjective knowledge associated with the human factor into the valuation process. It combines two of the most extended multicriteria decision making techniques: the Analytic Hierarchy Process (AHP) and Goal Programming (GP). The first of these enables tangible and intangible information stemming from known elements to be collected by using pairwise comparisons; the second allows the scarce information available and the personal approach to the valuation to be included in the valuation process. The proposed methodology is illustrated by means of its application to a case of individual and group valuation of an agricultural asset in the La Ribera district, Valencia (Spain). [ABSTRACT FROM AUTHOR]

Abstract: In recent years, fuzzy models have been acknowledged as a suitable approach for species distribution modelling due to their transparency and their ability to incorporate the ecological gradient theory. Specifically, the overlapping class boundaries of a fuzzy model are similar to the transitions between different environmental conditions. However, the need for ecological expert knowledge is an important constraint when applying fuzzy species distribution models. Moreover, the consistency of the ecological preferences of some fish species across different rivers has been widely contested. Recent research has shown that data-driven fuzzy models may solve this ‘knowledge acquisition bottleneck’ and this paper is a further contribution. The aim was to analyse the brown trout (Salmo trutta fario L.) habitat preferences based on a data-driven fuzzy modelling technique and to compare the resulting fuzzy models with a commonly applied modelling technique, Random Forests. A heuristic nearest ascent hill-climbing algorithm for fuzzy rule optimisation and Random Forests were applied to analyse the ecological preferences of brown trout in 93 mesohabitats. No significant differences in model performance were observed between the optimal fuzzy model and the Random Forests model and both approaches selected river width, the cover index and flow velocity as the most important variables describing brown trout habitat suitability. Further, the fuzzy model combined ecological relevance with reasonable interpretability, whereas the transparency of the Random Forests model was limited. This paper shows that fuzzy models may be a valid approach for species distribution modelling and that their performance is comparable to that of state-of-the-art modelling techniques like Random Forests. Fuzzy models could therefore be a valuable decision support tool for river managers and enhance communication between stakeholders. [Copyright &y& Elsevier]

In this paper the Analytic Network Process (ANP) is applied to select the best location for the construction of a municipal solid waste (MSW) plant in the Metropolitan area of Valencia (Spain). Selection of the appropriate MSW facility location can be viewed as a complex multicriteria decision-making problem that requires an extensive evaluation process of the potential MSW plant locations and other factors as diverse as economic, technical, legal, social or environmental issues. The decision-making process includes the identification of six candidate MSW plant sites and 21 criteria grouped into clusters for the construction of a network. Two technicians of the Metropolitan Waste Disposal Agency acted as decision makers (DMs). The influences between the elements of the network were identified and analyzed using the ANP multicriteria decision method. Two different ANP models were used: one hierarchy model (that considers AHP as a particular case of ANP) and another network-based model. The results obtained in each model were compared and analyzed. The strengths and weaknesses of ANP as a multicriteria decision analysis tool are also described in the paper. The main findings of this research have proved that ANP is a useful tool to help technicians to make their decision process traceable and reliable. Moreover, this approach helps DMs undertake a sound reflection of the siting problem. [Copyright &y& Elsevier]

Social trust and political trust are, amongst others, key social capital factors. This paper examines the accuracy of their measurement and comparability across different time periods. Multiple-group confirmatory factor analysis (MGCFA) is performed and different levels of measurement invariance (configural, metric and scalar) are tested. Data used are from European Social Survey for the years 2002, 2004, 2006 and 2008, in relation to Spanish citizens. Factor means for social and political trust are compared across time in Spain. Political and social trust show stability across time, except in 2004 with a higher level of political trust and 2006 with a higher level of social trust in Spain. Comparison with traditional composite scores shows the inaccuracy of such measurement for data comparison across time. Finally, consequences of using inaccurate measurements, and methodological recommendations concerning model fit structural equation models are delineated. [ABSTRACT FROM AUTHOR]

Background Egalitarianism and altruism are two ways in which people may have attitudes that go beyond the narrowly defined selfish preferences. The theoretical constructs of egalitarianism and altruism are different from each other, yet there may be connections between the two. This paper explores the empirical relationship between egalitarianism and altruism, in the context of health. Methods We define altruism as individual behaviour that aims to benefit another individual in need; and egalitarianism as a characteristic of a social welfare function, or a meta-level preference. Furthermore, we specify a model that explains the propensity of an individual to be egalitarian in terms of altruism and other background characteristics. Individuals who prefer a hypothetical policy that reduces socioeconomic inequalities in health outcomes over another that does not are regarded 'egalitarian' in the health domain. On the other hand, 'altruism' in the health context is captured by whether or not the same respondents are (or have been) regular blood donors, provided they are medically able to donate. Probit models are specified to estimate the relationship between egalitarianism and altruism, thus defined. A representative sample of the Spanish population was interviewed for the purpose (n = 417 valid cases). Results Overall, 75% of respondents are found to be egalitarians, whilst 35% are found to be altruists. We find that, once controlled for background characteristics, there is a statistically significant empirical relationship between egalitarianism and altruism in the health context. On average, the probability of an altruist individual supporting egalitarianism is 10% higher than for a non-altruist person. Regarding the other control variables, those living in high per capita income regions have a lower propensity and those who are politically left wing have a higher propensity to be an egalitarian. We do not find evidence of a relationship between egalitarianism and age, socioeconomic status or religious practices. Conclusion Altruist individuals have a higher probability to be egalitarians than would be expected from their observed background characteristics. [ABSTRACT FROM AUTHOR]

Abstract: Many organizations are implementing process improvement models, seeking to increase their organizational maturity for software development. However, implementing traditional maturity models involves a large investment (as regards money, time and resources) which is beyond the reach of vast majority of small organizations. This paper presents the use and adaptation of some ISO models in the creation of an organizational maturity model for the Spanish software industry. This model was used satisfactorily to (i) improve the software processes of several Spanish small firms, and (ii) obtain an organizational maturity certification for software development, granted by the Spanish Association for Standardization and Certification. [Copyright &y& Elsevier]

Inside of the new communication model determined by the multimedia convergence, TV second screen apps for mobile devices are increasing slowly in Spain. The one with higher implantation and range is Ant 3.0, hence its interest to be analyzed. This paper invites to know, from the practice, how it works and the main services provided by the first contents synchronized app in Spain after having an approach to the concept of second screen activity. So the field work has lied in following a second screen session and a broadcast of Gran Hotel series episode has been chosen. As a result, Ant 3.0 app gets defined as a complete second screen experience with interactive contents that develops the spectator's loyalty and makes him being involved, in this case, in solving the mysteries of the plot. [ABSTRACT FROM AUTHOR]

Abstract: Evidence shows that divorces are related to the economy and social contagion, as well as to the existence of a difference in happiness between the couple. This paper deals with the mathematical modeling of divorce propagation allowing the estimation of the future divorced population. We use a coupled discrete linear-quadratic difference system model and data collected from the Spanish Statistics Institute (INE). A sensitivity analysis of the growth of the divorced population with respect to the contagion rate is included, and several different economic scenarios are considered. [Copyright &y& Elsevier]

Abstract: Anxiolytics (AX) are the psychotropic drugs prescribed for the treatment of anxiety and insomnia for 2–4 weeks, for longer periods of consumption (>1 month) may lead to the development of tolerance or addiction. In fact, its prescription was 16% of the total pharmaceutical expenditure in Spain in 2007. This paper deals with the development of a mathematical model describing the dynamic of the addiction to AX for the case study of the Spanish region of Castellón. The reasons believed to cause the development of addicts to AX are the economic situation, the marriage termination and the social contact. The simulations performed to forecast the addicts rate for the period 2010–2014 showed an increase from 6% in 2010 to 14% in 2014 with a fluctuation of about 2% between the possible economic scenarios. Finally, the analysis of sensitivity of the rate of addicts to the fluctuation of the social contact parameters was performed, letting us estimate its impact on the pharmaceutical expenditure. [Copyright &y& Elsevier]

This paper deals with the construction of a discrete population mathematical model for the short-term forecast until January 2016 of the electoral support of extreme ideology parties in Spain. Firstly, the nontrivial concept of extreme ideology is stated. Then, the electoral register is split in three subpopulations: supporters of extremist parties, abstentions/blank voters, and supporters of establishment parties. The model takes into account the following variables: economy measured throughout the Spanish unemployment rate; demography quantified in terms of birth and death rates and emigration; sociopolitical situation measured by the Spanish poverty indicator, trust on theGovernment labor indicator (GLI), and the indicator of political trust. By considering the dynamic subpopulations transits built throughout data obtained from public and private prestigious institutions and sociopolitical analysis, a system of difference equations models the electoral population behavior in Spain allowing us to compute the expected electoral support in the time horizon of January 2016. Sensitivity analysis versus uncertain parameters is performed in order to improve the reliability of the model results. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, we present an extension to the mixed-model sequencing problem with work overload minimisation (MMSP-W) for production lines with serial workstations and parallel homogeneous processors. The extension is intended to meet the industrial need to sequence various products so that the work required and completed at the workstations over time is as constant as possible. Several approaches are proposed to formulate the problem, giving rise to different models. Four models are selected, and their performances are compared after running the Gurobi solver, using instances from the literature and a case study of the Nissan powertrain plant in Barcelona. [Copyright &y& Elsevier]

Abstract: Sustainable tourism is being consolidated at an international level as an approach that should be used to make all types of tourism more environmentally, socially and economically beneficial. A common practice is to use an indicator system for designing and implementing tourism models that focuses on the sustainability approach. Indicators are considered as useful tools that allow tourism managers to diagnose the situation of the destination, and to identify and evaluate issues that require addressing to improve the level of sustainability of the tourist activities. However, these indicator systems usually do not provide a practical guide to establish how to interpret information and how to integrate it into the decision-making. In this paper we present an indicator system to evaluate sustainable tourism at cultural destinations. Likewise, we suggest a method based on goal programming to construct composite indicators. The definition of the indicator system and composite indicators is completed providing guidelines that establish how to use these tools in tourism sector planning. Specifically, we propose three basic practical uses for these tools: the formulation of general action plans at a regional level, the definition of short-term strategies for destinations and the establishment of destination benchmarking practices. Each practical use is illustrated using the case of cultural tourism destinations in the Andalusia region (Spain). [Copyright &y& Elsevier]

Abstract: With the re-emergence of insurgency tied to terrorism, governments need to strategically manage their communications. This paper analyzes the effect of the Spanish government''s messaging in the face of the Madrid bombing of March 11, 2004: unlike what happened with the 9/11 bombings in the USA and the 7/07 London attacks, the Spanish media did not support the government''s framing of the events. Taking framing as a strategic action in a discursive form (), and in the context of the attribution theory of responsibilities, this research uses the “cascading activation” model () to explore how a framing contest was generated in the press. Analysis of the coverage shows that the intended government frame triggered a battle among the different major newspapers, leading editorials to shift their frame over the four days prior to the national elections. This research analyzes strategic contests in framing processes and contributes insight into the interactions among the different sides (government, parties, media, and citizens) to help bring about an understanding of the rebuttal effect of the government''s intended frame. It also helps to develop an understanding of the role of the media and the influence of citizens’ frames on media content. [Copyright &y& Elsevier]

Abstract: This paper presents a regression analysis of energy consumption in the banking sector. In our case study, the target area is the Spanish banking sector, for which we divide the available data into a prediction and a validation subset. Power models were developed using test data from 55 banks. From the analysis, three models were obtained; where the first proposed model can be used to predict the energy consumption of the whole banking sector, while the rest of the models estimate the energy consumption for branches with low winter climate severity (Model 2) and high winter climate severity (Model 3). Models 2 and 3 differ from the first model in that they need independent variables measured in situ. As a result, the uncertainty of the response variable in the function of the independent variables is reduced by 56.8% for the first model and by 65.2% and 68.5% for the second and third proposed models, respectively. The validation of the first model, which is the model with the lowest determination coefficient, shows that this model is appropriate for predicting the energy consumption of bank branches with good energy consumption performance and detecting inefficiencies in bank branches with poor energy consumption performance. [Copyright &y& Elsevier]

Abstract: The present work shows the application of a new methodology, to find out the free surface inside earth fill dams under steady flow conditions, to a real field case: the Gasset Dam, in Ciudad Real, Spain. An accurate and fast computation of the free surface is of paramount importance, since it is a previous and necessary step for evaluating the safety of an earth dam in terms of its stress–strain behavior. This new methodology is based on a coupled numerical model formulated in terms of displacements (so called u–w formulation) instead of a more usual approach of water heads. The developed general code has been previously validated using several theoretical seepage problems through porous media. The selected field case is an earth dam built a century ago, which has been subjected to several rehabilitation works since then. Hence, it is a very irregular and nonhomogeneous dam. The comparison of computations and real field measurements, in terms of the free surface location and the total discharge through the dam under steady conditions, is presented in this paper, demonstrating the accuracy and applicability of this formulation to this kind of problems. [Copyright &y& Elsevier]

Ensembles of numerical model forecasts are of interest to operational early warning forecasters as the spread of the ensemble provides an indication of the uncertainty of the alerts, and the mean value is deemed to outperform the forecasts of the individual models. This paper explores two ensembles on a severe weather episode in Spain, aiming to ascertain the relative usefulness of each one. One ensemble uses sensible choices of physical parameterizations (precipitation microphysics, land surface physics, and cumulus physics) while the other follows a perturbed initial conditions approach. The results show that, depending on the parameterizations, large differences can be expected in terms of storm location, spatial structure of the precipitation field, and rain intensity. It is also found that the spread of the perturbed initial conditions ensemble is smaller than the dispersion due to physical parameterizations. This confirms that in severe weather situations operational forecasts should address moist physics deficiencies to realize the full benefits of the ensemble approach, in addition to optimizing initial conditions. The results also provide insights into differences in simulations arising from ensembles of weather models using several combinations of different physical parameterizations. [ABSTRACT FROM AUTHOR]

Abstract: The implementation of urban sustainability practices is affected by political obstacles, and diverse political ideologies may defend different city models. Sustainable policy design could also be affected by several factors that cause the deflection of resources initially allocated to other groups that are contrary to the concerns pursued and have the power to veto sustainable plans by exerting pressure on the party in power. In this sense, the aim of this paper is to show the impact that political factors have on cities’ sustainability, and the effect of both on cities’ economic development. To do so, we used the 78 Spanish cities with a population over 100,000 studied by MERCO (Spanish Corporate Reputation Monitor) as regards their levels of sustainability for the fiscal years 2008 and 2009. Both relationships have been tested empirically through two dependence models using linear regression techniques. The results obtained show that political competition improves cities’ sustainability, while a leftist ideology has an inverse impact. On the other hand, a significant direct relationship has been observed between urban sustainability and municipal economic activity. [Copyright &y& Elsevier]

During the first decade of the new millennium, fueled by the economic development in Spain, urban bus services were extended. Since the years 2008 and 2009, the root of the economic crisis, the improvement of these services is at risk due to economic problems. In this paper, the technical efficiency of the main urban bus companies in Spain during the 2004-2009 period are studied using SBM (slack-based measures) models and by establishing the slacks in the services' production inputs. The influence of a series of exogenous variables on the operation of the different services is also analyzed. It is concluded that only the 24% of the case studies are efficient, and some urban form variables can explain part of the inefficiency. The methodology used allows studying the inefficiency in a disaggregated way that other DEA (data envelopment analysis) models do not. [ABSTRACT FROM AUTHOR]

Abstract: Competitive structure of power markets causes various challenges for wind resources to participate in these markets. Indeed, production uncertainty is the main cause of their low income. Thus, they are usually supported by system operators, which is in contrast with the competitive paradigm of power markets. In this paper, a new strategy for increasing the profits of wind resources is proposed. In the suggested strategy, a Generation Company (GenCo), who owns both wind and pumped-storage plants, self-schedules the integrated operation of them regarding the uncertainty of wind power generation. For presenting an integrated self-schedule and obtaining a real added value of the strategy, participation of the GenCo in energy and ancillary service markets is modeled. The self-scheduling strategy is based on stochastic programming techniques. Outputs of the problem include generation offers in day-ahead energy market and ancillary service markets, including spinning and regulation reserve markets. A Neural Network (NN) based technique is used for modeling the uncertainty of wind power production. The proposed strategy is tested on a real wind farm in mainland, Spain. Moreover, added value of the strategy is presented in different conditions of the market. [Copyright &y& Elsevier]

In this paper we present some reflections on the application of the technique of content analysis in the study of historical texts in mathematics. This work is based on a study conducted in 2009 on the treatment of the metric system in mathematics texts in Spain in which a selection of texts published in the second half of the nineteen century was analyzed. The study provided the identification of three stages that characterize the texts used for the dissemination of new Spanish weights and measures in the selected period. [ABSTRACT FROM AUTHOR]

Work-related accidents involve significant human and economic costs for the companies, people, and society. Said accidents usually represent a great negative economic impact for the construction industries, which support a higher cost than reflected due to the large amount of hidden variables are unknown. Until now, the evaluation of the costs generated by labor accidents has been based on the development of very different methods and, as Duran [1] has not made any kind of economic assessment that comprehensively considers the economic cost of damage to health associated with work, this paper present a mathematical model applicable to the Spain construction industry, that the cost of labor accidents, is the consumption of material and human resources derived from insurance, prevention and accidents. [ABSTRACT FROM AUTHOR]

This paper analyses both the processes of adoption and diffusion of the practice of using the chopped residues of pruning as mulch in the olive orchards of the Southern Spanish province of Granada, one of the major olive-producing areas in the world. Many olive groves in the area are located on steep areas where the risk of soil erosion is high. A majority of farmers have adopted no tillage, as an alternative to traditional tillage, combined with either vegetation soil covers or, more frequently, using the chopped pruning residues as mulch. The data used comes from a survey carried out in 2005 to 215 olive farmers. From farmers’ responses we estimate a binomial probit model to identify some socio-economic and institutional factors related to the decision to use the practice of mulching on a regular basis. We also estimate several diffusion models that describe the spatial and temporal spread of mulching among farmers. Our results show that mulching using the pruning residues is adopted by 43% of the surveyed farmers. The diffusion process of this practice has been very intense since the middle nineties, and seems to have been based on the interactions among farmers in the area of study rather than in other external source of information. Some of the relevant identified factors that affect the probability of adoption of this practice are farmer’s experience, the level of soil degradation in the farm or the continuity of farming by some relative. [Copyright &y& Elsevier]

Abstract: Damage caused to objects of cultural heritage is one of the most serious detrimental effects of air pollutants. Within the 6th Framework Programme of the EU, the CULT-STRAT project is an inter-agency, multi-disciplinary project that has integrated research and monitoring information to provide answers to policy and management questions, which relate the effects of air pollutants on heritage and the management options available to mitigate them. The overall aim of the project has been to assess and predict the effects of different pollutants on materials and objects of cultural heritage in a multipollutant scenario and to identify indicators and thresholds levels of pollutants. These have been used for development of management strategies for sustainable maintenance and preventive conservation of European Cultural Heritage and air quality policy from continental to local scale. The present paper reports one of the studies carried out in the CULT-STRAT project at city level and focused on the town of Madrid (Spain). Different maps are shown for the present and possible future scenarios (2010 and 2020): inventory of stock of cultural heritage for each selected material, concentration of selected pollutants (SO2, NO2, O3 and PM10), corrosion (cast bronze) and recession (Portland limestone), exceedance of tolerable degradation thresholds for each material and corrosion-cultural heritage overlapped maps. [Copyright &y& Elsevier]

This paper describes the application of sliced inverse regression to model the electrochemical process of aluminum smelter plants. Real data measurements obtained during several years in a Spanish industrial environment are used to illustrate the main dependencies between parameters. Nonlinear relations between the output variables and relevant linear combinations of input variables are deduced. An exploratory statistical analysis is also presented, checking for correlations and possible linear dependencies. [ABSTRACT FROM AUTHOR]

Abstract: This paper proposes a novel price forecasting method based on wavelet transform combined with ARIMA and GARCH models. By wavelet transform, the historical price series is decomposed and reconstructed into one approximation series and some detail series. Then each subseries can be separately predicted by a suitable time series model. The final forecast is obtained by composing the forecasted results of each subseries. This proposed method is examined on Spanish and PJM electricity markets and compared with some other forecasting methods. [ABSTRACT FROM AUTHOR]

Abstract: Over the last few years electronic commerce, e-commerce for short, has become one of the most accepted purchasing systems this having became the easiest way of accessing a large variety of goods. E-commerce provides: the possibility of comparing costs and bids without going to outlets and therefore, saving time and money; the availability of detailed characteristics of goods; the possibility of acquiring new goods available abroad. Moreover, the form of payments are getting progressively safer and more reliable on the Internet. In this paper we develop a mathematical model to study future short-term trends of e-commerce in Spain. To do this, we divide the total population into age groups and each age group into two subgroups: the first one consists of people adopting this technology and the second one who do not. Then, we consider a nonlinear diffusion model whose parameters are the innovation coefficients associated with each age group and related to advertising, and the imitation coefficients related to the influence of an adopting technology group on non-adopting group. These parameters are estimated by fitting the available real data from the Spanish Statistic Institute. Finally, an analysis of statistic sensitivity is included. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, a mathematical model for alcohol consumption in Spanish population is proposed. Its parameters are estimated by fitting the model to real data from Spanish Ministry of Health. Predictions about the future behavior of the alcohol consumption in Spain are presented using this model. Results are applied to estimate the economic costs (sanitary and non-sanitary) assumed by Spanish society that are derived from this consumption. [ABSTRACT FROM AUTHOR]

Abstract: Cocaine consumption is a social problem with acute consequences and its dependency can be regarded as a health concern of social transmission. This fact leads us to develop the idea that its transmission dynamics can be studied using epidemiological mathematical models. Under this point of view, in this paper we propose a network model to study the short-term evolution of the cocaine consumer subpopulations. The model parameters are obtained from data source and from an analogue continuous model. Sensitivity of the model parameters is studied. The parameters are associated with prevention and treatment policies and the sensitivity study gives us information about which parameters have more incidence on the future evolution of consumers. Results and discussion are also presented. [ABSTRACT FROM AUTHOR]

Abstract: Most of the marine pollution attributable to ship actions is associated with the illicit discharge of oily residues or ballast water, in what is commonly termed operational pollution. In the particular case of ballast water, careless disposal can lead to severe ecological damage, including the irreversible establishment of communities of invasive species. In its 2004 Convention on ballast water management, the International Maritime Organisation defined the measures to be followed to prevent these environmental issues, including the exchange with mid-oceanic water at a minimum distance from the shore. This paper uses two numerical models to analyse the effects of several factors on the dilution of a discharge from a ship moving in the Spanish Mediterranean waters, in order to determine under which conditions the environmental impact of the discharge will be minimum. The results highlight the dual role played by a freshwater plume, which may contribute either to decrease or to enhance the onshoreward transport of the discharged substance, and the relevance of the ship''s speed in determining the dilution rates. [Copyright &y& Elsevier]

Abstract: Trigeneration systems, also known as Combined Heat, Cooling and Power (CHCP) systems, are interesting alternatives to supply different energy services in urban districts and in large buildings, particularly in warm areas such as Mediterranean countries. These systems can provide substantial benefits from economic, energetic, and environmental viewpoints, since the cogenerated heat can be used for heating in winter as well as cooling in summer with an absorption refrigerator. This paper develops an optimization model using Mixed Integer Linear Programming (MILP) to determine the type, number and capacity of equipment in CHCP systems installed in the tertiary sector as well as to establish the optimal operation mode for the different plant components on an hour-by-hour basis throughout the year. The objective function to be minimized is the annual total cost. The optimization model considers the legal constraints imposed to feed the surplus autogenerated electricity into the grid at a regulated feed-in tariff. The optimization model is applied to design a system providing energy services for a hospital located in the city of Zaragoza (Spain). The effects of the financial market conditions and energy prices in the optimal structure of the system are analyzed. [Copyright &y& Elsevier]

The accuracy of environmental valuation studies relies, to a great extent, on the suitability of the proxy measures used to capture individuals' preferences. While important advances have been achieved in the last years concerning the characterization of the physical background in which recreational choices are made, Travel Cost Method applications have failed to consider the heterogeneity of landscape and the spatial configuration of land use. This paper presents an empirical application to forest recreation in Mallorca (Spain), implementing a random parameter logit model to evaluate in terms of goodness-of-fit, model predictions and welfare measurements the effects of environmental diversity on the recreational site-choice process. [Copyright &y& Elsevier]

Abstract: This paper presents a kinematic study of the Portalet landslide (Sallent de Gállego, Central Spanish Pyrenees), which was triggered by the construction of a big parking area at the toe of the slope. A description of the landslide from a geomorphological point of view is first introduced. The measurements of displacement performed by conventional (total station, inclinometers and differential GPS) and advanced (GB-SAR) ground monitoring techniques are presented and GB-SAR and DGPS datasets are compared. The correlation between measured displacements and rainfall series indicates that the landslide is very sensitive to rainfall. The continuous GB-SAR measurements from the 5th of October 2006 to the 21st of November 2006 at a rate of 1/h were used to calibrate a simple 1D infinite model by back analysis. The model includes a viscoplastic behaviour and takes into account directly the known daily rainfall intensity and the dissipation of the excess pore-fluid through a simple consolidation equation. Prediction was made in an extended period of time, from May 2006 to July 2007, and compared to the DGPS measurements. [Copyright &y& Elsevier]

Abstract: A previous study on seabed sediments of the Bay of Cadiz (SW of Spain) enabled us to identify several relations between sedimentological variables and activity concentrations of environmental radionuclides such as 137Cs, 226Ra, 232Th and 40K. In this paper the study has been extended to a large neighbouring inter-tidal area in order to establish if the above mentioned models can be generalized. As a result we have determined that the measured activity concentrations are closely to the values predicted by the theoretical models (correlation coefficient range=0.85–0.93). Furthermore, the proposal model for granulometric facies as a function of activity concentrations of the abovementioned radionuclides provides for the sediments distribution a representation which agrees with the values of the tidal energy distribution obtained using numeric models calibrated with experimental data from current meters and water level recorders. [Copyright &y& Elsevier]

This paper is concerned with mathematical modelling in the management of a wastewater treatment system. The problem is formulated as looking for a Nash equilibrium of a multiobjective pointwise control problem of a parabolic equation. Existence of solution is proved and a first order optimality system is obtained. Moreover, a numerical method to solve this system is detailed and numerical results are shown in a realistic situation posed in the estuary of Vigo (Spain).? [ABSTRACT FROM AUTHOR]

Abstract: The paper compares the wave hindcast in the Western Mediterranean sea using the reanalysis wind fields from HIPOCAS and ERA-40 from ECMWF for November 2001. The study has concentrated on the Mediterranean coast of Spain where there are known difficulties with the wind and wave modelling. Two winter storms have been compared. The main differences between the significant wave heights using the ERA-40 reanalysis (ECMWF) and HIPOCAS reanalysis winds were observed to increase when moving southwards in the geographical domain at the offshore locations. Systematic negative biases of Hs were obtained with the ERA-40 data at all the coastal locations analyzed, whereas positive biases are typical for the HIPOCAS reanalysis. For offshore and coastal locations when using the ERA-40 data the Hs biases increased moving to South, while this pattern was not so clear for the HIPOCAS data. The inconsistencies in the comparisons of modelled waves against measurements seem to be associated with the quality of the wind fields. [Copyright &y& Elsevier]

In this paper we introduce an asymmetric model of continuous electricity auctions with limited production capacity and bounded supply functions. The strategic bidding is studied with this model by means of an electricity market game. We prove that for every electricity market game with continuous cost functions a mixed-strategy Nash equilibrium always exists. In particular, we focus on the behavior of producers in the Spanish electricity market. We consider a very simple form for the Spanish electricity market: an oligopoly consisting just of independent hydro-electric power production units in a single wet period. We show that a pure-strategy Nash equilibrium for the Spanish electricity market game always exists. [ABSTRACT FROM AUTHOR]