Choice of Metrics used in Collaborative Filtering and their Impact on Recommender Systems

The capacity of recommender systems to make correct predictions is essentially determined by the quality and suitability of the collaborative filtering that implements them. The common memory-based metrics are Pearson correlation and cosine, however, their use is not always the most appropriate or sufficiently justified. In this paper, we analyze these two metrics together with the less common mean squared difference (MSD) to discover their advantages and drawbacks in very important aspects such as the impact when introducing different values of k-neighborhoods, minimization of the MAE error, capacity to carry out a sufficient number of predictions, percentage of correct and incorrect predictions and behavior when attempting to recommend the n-best items. The paper lists the results and practical conclusions that have been obtained after carrying out a comparative study of the metrics based on 135 experiments on the MovieLens database of 100,000 ratios

Construcciones fílmicas de personajes históricos en el cine español (2000-2010)

El cine de talante biográfico tiene un grupo de obras significativas en el cine español del nuevo siglo; el género adquiere una diversidad notable de formatos y tratamientos, lo que permite abundar en las estrategias narrativas de esta clase de no ficción. Junto al espectáculo y las vidas novelescas de personajes históricos más remotos hay homenajes a personajes públicos actuales y aproximaciones más complejas a creadores y pensadores, así como retratos familiares y miradas personales de cineastas. En algunos títulos se han elegido tipos con vidas extravagantes o protagonistas de sucesos dramáticos atractivos para la pantalla

Brand activism

In this work, brand activism is defined as a strategy that seeks to influence citizen-consumers by means of campaigns created and sustained by political values. It involves a transformation in corporate communication management and social responsibility practices, which borrows from those of social movements to contribute to the social production of identity of citizen-consumers. This corporate political shift involves the use of messages, slogans and content based on final (of common interest) or instrumental (linked to the industry in which they are applied) political values. Political behaviour does not operate in a vacuum but is the response to a change in values of the young generations employing digital technologies and demanding a different behaviour from global firms. However, these political advertising practices have been heavily criticised in the field of political economy, insofar as it is contended that they are impostures lacking authenticity. Thus, 45 campaigns were analysed to determine the characteristics of brand activism in this new socio-political context. From the results it follows that this activist practice, of Anglo-Saxon origin, is a relevant trend in political communication because it aligns individual identity, the management of public assets and corporate action in the political sphere

Multi-Agent Architecture with Support to Quality of Service and Quality of Control

The final publication is available at Springer via http://dx.doi.org/10.1007/978-3-642-15381-5_17Multi Agent Systems (MAS) are one of the most suitable frameworks for the implementation of intelligent distributed control system. Agents provide suitable flexibility to give support to implied heterogeneity in cyber-physical systems. Quality of Service (QoS) and Quality of Control (QoC) parameters are commonly utilized to evaluate the efficiency of the communications and the control loop. Agents can use the quality measures to take a wide range of decisions, like suitable placement on the control node or to change the workload to save energy. This article describes the architecture of a multi agent system that provides support to QoS and QoC parameters to optimize de system. The architecture uses a Publish-Subscriber model, based on Data Distribution Service (DDS) to send the control messages. Due to the nature of the Publish-Subscribe model, the architecture is suitable to implement event-based control (EBC) systems. The architecture has been called FSACtrlThe architecture described in this article is a part of the coordinated project SIDIRELI: Distributed Systems with Limited Resources. Control Kernel and Coordination. Education and Science Department, Spanish Government and FEDER funds.Poza-Lujan, J.; Posadas-Yagüe, J.; Simó Ten, JE. (2010). Multi-Agent Architecture with Support to Quality of Service and Quality of Control. En Intelligent Data Engineering and Automated Learning – IDEAL 2010. Springer Verlag (Germany). 137-144. doi:10.1007/978-3-642-15381-5_17S137144Lee, E.A.: Cyber Physical Systems: Design Challenges. In: 11th IEEE Symposium on Object Oriented Real-Time Distributed Computing, pp. 363–369 (2008)Siegel, J.: CORBA 3: Fundamentals and Programming. OMG (2000)FIPA. FIPA-QoS (2002), http://www.fipa.org/specs/fipa00094Object Management Group (OMG): Data Distribution Service for Real-Time Systems, v1.1. Document formal (2005-12-04)Posadas, J.L., Poza, J.L., Simó, J.E., Benet, G., Blanes, F.: Agent Based Distributed Architecture for Mobile Robot Control. Engineering Applications of Artificial Intelligence 21(6), 805–823 (2008)Aurrecoechea, C., Campbell, A.T., Hauw, L.: A Survey of QoS Architectures. Multimedia Systems Journal, Special Issue on QoS Architecture 6(3), 138–151 (1998)Pardo-Castellote, G.: OMG Data-Distribution Service: architectural overview. In: Proceedings of 23rd International Conference on Distributed Computing Systems Workshops, Providence, USA, vol. 19(22), pp. 200–206 (2003)International Telecommunication Union (ITU). Terms and Definitions Related to Quality of Service and Network Performance Including Dependability. ITU-T Recommendation E.800 (0894) (1994)Sánchez, J., Guarnes, M.Á., Dormido, S.: On the Application of Different Event-Based Sampling Strategies to the Control of a Simple Industrial Process. Sensors 9, 6795–6818 (2009)Dorf, R.C., Bishop, R.H.: Modern Control Systems, 11th edn. Prentice Hall, Englewood Cliffs (2008)Poza, J.L., Posadas, J.L., Simó, J.E.: Middleware with QoS Support to Control Intelligent Systems. In: 2th International Conference on Advanced Engineering Computing and Applications in Sciences, ADVCOMP, pp. 211–216 (2008)Poza, J.L., Posadas, J.L., Simó, J.E.: From the Queue to the Quality of Service Policy: A Middleware Implementation. In: Omatu, S., Rocha, M.P., Bravo, J., Fernández, F., Corchado, E., Bustillo, A., Corchado, J.M. (eds.) IWANN 2009. LNCS, vol. 5518, pp. 432–437. Springer, Heidelberg (2009

Effect of a multi-citrus extract-based feed additive on the survival of rainbow trout (Oncorhynchus mykiss) following challenge with Lactococcus garvieae

Growing global concerns about antibiotic resistance have generated a considerable interest in the search for alternative environmental-friendly approaches. This study was aimed to assess the antimicrobial activity of a multi-citrus extract-based feed additive (Biocitro®) against some fish pathogens, as well as evaluate its capacity to protect rainbow trout (Oncorhynchus mykiss) to lactococcosis. A broth dilution method was used to determine the minimum inhibitory concentration (MIC) of Biocitro®, and the results showed a strong antibacterial activity against Aeromonas salmonicida, Lactococcus garvieae and Yersinia ruckeri with MIC values of 2.0 µg/mL. Afterwards, rainbow trout juveniles were fed a Biocitro®-enriched diet (750 mg/kg feed) at a daily rate of 1.5% body weight for 4 weeks, then they were challenged with L. garvieae by the cohabitation method. At the end of the experimental period, fish treated with Biocitro® showed significantly (P¿<¿0.001) improved protection against L. garvieae compared to control fish. Although further studies are needed to understand how Biocitro® increases rainbow trout resistance to L. garvieae, this feed additive could be considered as a useful alternative to chemotherapeutic treatment in aquaculture

Relation between the raise to span ratio and the real ultimate lateral strength for parabolic clamped arches considering different calculation hypothesis

En este artículo se proponen gráficas que relacionan los parámetros f/L y λ = qL3 /EIy para arcos biempotrados con diferentes secciones transversales y para diferentes hipótesis de cálculo. Para ello es necesario determinar la carga crítica lateral de una serie de arcos biempotrados considerando diferentes hipótesis de cálculo en lo que se refiere a la linealidad geométrica y a las características del material acero. La hipótesis de material elastoplástico con no linealidad geométrica considera la existencia de tensiones residuales e imperfecciones geométricas iniciales.Curved graphs that relate the f/L ratio and the λ = qL3 /EIy parameter for clamped arches with the different calculation hypothesis are going to be proposed in this article. It has been necessary to determine the real critical lateral strength of a series of clamped arches considering different calculation hypothesis respect to geometrical linearity and a steel material characteristic. The elastic-plastic material hypothesis with non geometrical linearity considers the existence of residual stresses and initial lateral deflection.Peer Reviewe

Nuevos materiales compuestos Si/carbono grafitizado como electrodos negativos de alta energía para baterías de litio-ión

II Encuentro sobre nanociencia y nanotecnología de investigadores y tecnólogos de la Universidad de Córdoba. NANOUC

Reusing intravaginal progesterone releasing devices for oestrous synchoronization in ewes

In this study, the second use of an intravaginal progesterone-releasing device or controlled intravaginal drug release device (CIDR) was evaluated. After a first use of 11 days, the CIDR was again used for either nine or 12 days with 200 or 300 IU equine chorionic gonadotrophin (eCG) being injected on its removal. Sixty-four ewes were randomly distributed to four treatments (n=16/group): CIDR9+eCG200, CIDR9+eCG300, CIDR12+eCG200, and CIDR12+eCG300. The eCG was administered intramuscularly on withdrawal of the device. Thus, the experiment was a completely randomized design with a 2×2 factorial arrangement of treatments. Oestrus presentation did not differ between treatments (P =0.29). However, with the dose of 200 IU of eCG, oestrus presentation tended to increase (P =0.08). The onset and duration of oestrus, percentage of gestation, and return to oestrus did not differ between treatments (P &gt;0.05). Progesterone concentration in serum was greater (P &lt; 0.05) in ewes treated with CIDR12+eCG300. Prolificacy was greatest (1.44) with the CIDR12+eCG300 treatment and was different (P = 0.001) from the treatments CIDR9+eCG200 (1.21) and CIDR9+eCG300 (1.20), but not from the CIDR12+eCG200 treated ewes (1.31). The CIDR12+eCG300 treatement produced the highest percentage of twin births (45.8%) (P =0.001). Leaving the device in place for 12 days increased (P =0.001) the incidence of twin births. Use of the CIDR for a second time synchronized oestrus in ewes successfully with better fertility being obtained when the device was left in place for 12 days, and 300 IU of eCG was injected on its removal. Key words: gonadotropin, progesterone device, synchronizatio

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A formula for the Bloch vector of some Lindblad quantum systems

Using the Bloch representation of an N-dimensional quantum system and immediate results from quantum stochastic calculus, we establish a closed formula for the Bloch vector, hence also for the density operator, of a quantum system following a Lindblad evolution with selfadjoint Lindblad operators.Comment: Accepted in Phys. Lett. A (shorter version than original