Repositorios en la nube

Las aplicaciones que se distribuyen a través de Internet como un servicio (Software as a service, SaaS) y el hardware y software de base de los centros de datos (Nube, Cloud) son los dos elementos de la ecuación llamada cloud computing. En este paradigma, se juegan tres roles principales: proveedor del cloud, usuario del cloud que a su vez es proveedor de servicio (como los repositorios) y los usuarios finales del servicio. Los primeros se benefician de la especialización y las economías de escala; mientras que los segundos de una mayor elasticidad en el aprovisionamiento. En este sentido, DuraSpace ha creado un piloto llamado DuraCloud para probar el uso de tecnologías de almacenamiento en la nube para la preservación de contenido digital. El taller pretende describir los conceptos básicos del cloud, con ejemplos de donde se está usando este tipo de tecnología; y el impacto que puede tener en los repositorios digitales.

Chemical characterization of majolica from 14th-18th century production centers on the Iberian Peninsula: a preliminary neutron activation study

Majolica pottery is one of the most characteristic tableware produced during the Medieval and Renaissance periods. Majolica technology was introduced to the Iberian Peninsula by Islamic artisans during Medieval times, and its production and popularity rapidly spread throughout Spain and eventually to other locations in Europe and the Americas. The prestige and importance of Spanish majolica was very high. Consequently, this ware was imported profusely to the Americas during the Spanish Colonial period. Nowadays, Majolica pottery serves as an important horizon marker at Spanish colonial sites. A preliminary study of Spanish-produced majolica was conducted on a set of 246 samples from the 12 primary majolica production centers on the Iberian Peninsula. The samples were analyzed by neutron activation analysis (NAA), and the resulting data were interpreted using an array of multivariate statistical procedures. Our results show a clear discrimination between different production centers. In some cases, our data allow one to distinguish amongst shards coming from the same production location suggesting different workshops or group of workshops were responsible for production of this pre-industrial pottery.

Data mining and mall users profile

Marketing scholars have suggested a need for more empirical research on consumer response to malls, in order to have a better understanding of the variables that explain the behavior of the consumers. The segmentation methodology CHAID (Chi-square automatic interaction detection) was used in order to identify the profiles of consumers with regard to their activities at malls, on the basis of socio-demographic variables and behavioral variables (how and with whom they go to the malls). A sample of 790 subjects answered an online questionnaire. The CHAID analysis of the results was used to identify the profiles of consumers with regard to their activities at malls. In the set of variables analyzed the transport used in order to go shopping and the frequency of visits to centers are the main predictors of behavior in malls. The results provide guidelines for the development of effective strategies to attract consumers to malls and retain them there.

Likelihood inferences with interval-censored data

En l’anàlisi de la supervivència el problema de les dades censurades en un interval es tracta, usualment,via l’estimació per màxima versemblança. Amb l’objectiu d’utilitzar una expressió simplificada de la funció de versemblança, els mètodes estàndards suposen que les condicions que produeixen la censura no afecten el temps de fallada. En aquest article formalitzem les condicions que asseguren la validesa d’aquesta versemblança simplificada. Així, precisem diferents condicions de censura no informativa i definim una condició de suma constant anàloga a la derivada en el context de censura per la dreta. També demostrem que les inferències obtingudes amb la versemblançaa simplificada són correctes quan aquestes condicions són certes. Finalment, tractem la identificabilitat de la funció distribució del temps de fallada a partir de la informació observada i estudiem la possibilitat de contrastar el compliment de la condició de suma constant.

Eliciting and fostering learners' metacognitive knowledge about language learning in self-directed learning programs: a review of data collection methods and procedures

Són molts els estudis que avui en dia incideixen en la necessitat d’oferir un suport metodològic i psicològic als aprenents que treballen de manera autònoma. L’objectiu d’aquest suport és ajudar-los a desenvolupar les destreses que necessiten per dirigir el seu aprenentatge així com una actitud positiva i una major conscienciació envers aquest aprenentatge. En definitiva, aquests dos tipus de preparació es consideren essencials per ajudar els aprenents a esdevenir més autònoms i més eficients en el seu propi aprenentatge. Malgrat això, si bé és freqüent trobar estudis que exemplifiquen aplicacions del suport metodològic dins els seus programes, principalment en la formació d’estratègies o ajudant els aprenents a desenvolupar un pla de treball, aquest no és el cas quan es tracta de la seva preparació psicològica. Amb rares excepcions, trobem estudis que documentin com s’incideix en les actituds i en les creences dels aprenents, també coneguts com a coneixement metacognitiu (CM), en programes que fomenten l’autonomia en l’aprenentatge. Els objectius d’aquest treball son dos: a) oferir una revisió d’estudis que han utilitzat diferents mitjans per incidir en el CM dels aprenents i b) descriure les febleses i avantatges dels procediments i instruments que utilitzen, tal com han estat valorats en estudis de recerca, ja que ens permetrà establir criteris objectius sobre com i quan utilitzar-los en programes que fomentin l’aprenentatge autodirigit.

Collaboration strategies and technological innovation: a contractual perspective of the relationship between firms and techonological centers

In this paper, a theoretical framework for analyzing the selection of governance structures for implementing collaboration agreements between firms and Technological Centers is presented and empirically discussed. This framework includes Transaction Costs and Property Rights’ theoretical assumptions, though complemented with several proposals coming from the Transactional Value Theory. This last theory is used for adding some dynamism in the governance structure selection. As empirical evidence of this theoretical explanation, we analyse four real experiences of collaboration between firms and one Technological Center. These experiences are aimed to represent the typology of relationships which Technological Centers usually face. Among others, a key interesting result is obtained: R&D collaboration activities do not need to always be organized through hierarchical solutions. In those cases where future expected benefits and/or reputation issues could play an important role, the traditional more static theories could not fully explain the selected governance structure for managing the R&D relationship. As a consequence, these results justify further research about the adequacy of the theoretical framework presented in this paper in other contexts, for example, R&D collaborations between firms and/or between Universities or Public Research Centers and firms.

The period function of the generalized Lotka-Volterra centers

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Modeling usage of medical care services: the medical expenditure panel survey data, 1996-2000

We explore the determinants of usage of six different types of health care services, using the Medical Expenditure Panel Survey data, years 1996-2000. We apply a number of models for univariate count data, including semiparametric, semi-nonparametric and finite mixture models. We find that the complexity of the model that is required to fit the data well depends upon the way in which the data is pooled across sexes and over time, and upon the characteristics of the usage measure. Pooling across time and sexes is almost always favored, but when more heterogeneous data is pooled it is often the case that a more complex statistical model is required.

Are one factor logarithmic volatility models useful to fit the features of financial data? An application to microsoft data.

This paper provides empirical evidence that continuous time models with one factor of volatility, in some conditions, are able to fit the main characteristics of financial data. It also reports the importance of the feedback factor in capturing the strong volatility clustering of data, caused by a possible change in the pattern of volatility in the last part of the sample. We use the Efficient Method of Moments (EMM) by Gallant and Tauchen (1996) to estimate logarithmic models with one and two stochastic volatility factors (with and without feedback) and to select among them.

Human capital in growth regressions: how much difference does data quality make? An update and further results

We construct estimates of educational attainment for a sample of OECD countries using previously unexploited sources. We follow a heuristic approach to obtain plausible time profiles for attainment levels by removing sharp breaks in the data that seem to reflect changes in classification criteria. We then construct indicators of the information content of our series and a number of previously available data sets and examine their performance in several growth specifications. We find a clear positive correlation between data quality and the size and significance of human capital coefficients in growth regressions. Using an extension of the classical errors in variables model, we construct a set of meta-estimates of the coefficient of years of schooling in an aggregate Cobb-Douglas production function. Our results suggest that, after correcting for measurement error bias, the value of this parameter is well above 0.50.

Real equilibrium exchange rates. A panel data approach for advanced and emerging economies.

Based on an behavioral equilibrium exchange rate model, this paper examines the determinants of the real effective exchange rate and evaluates the degree of misalignment of a group of currencies since 1980. Within a panel cointegration setting, we estimate the relationship between exchange rate and a set of economic fundamentals, such as traded-nontraded productivity differentials and the stock of foreign assets. Having ascertained the variables are integrated and cointegrated, the long-run equilibrium value of the fundamentals are estimated and used to derive equilibrium exchange rates and misalignments. Although there is statistical homogeneity, some structural differences were found to exist between advanced and emerging economies.

On the critical periods of perturbed isochronous centers

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