On certain greedoid polyhedra, partially indexable scheduling problems and extended restless bandit allocation indices

We present a polyhedral framework for establishing general structural properties on optimal solutions of stochastic scheduling problems, where multiple job classes vie for service resources: the existence of an optimal priority policy in a given family, characterized by a greedoid(whose feasible class subsets may receive higher priority), where optimal priorities are determined by class-ranking indices, under restricted linear performance objectives (partial indexability). This framework extends that of Bertsimas and Niño-Mora (1996), which explained the optimality of priority-index policies under all linear objectives (general indexability). We show that, if performance measures satisfy partial conservation laws (with respect to the greedoid), which extend previous generalized conservation laws, then theproblem admits a strong LP relaxation over a so-called extended greedoid polytope, which has strong structural and algorithmic properties. We present an adaptive-greedy algorithm (which extends Klimov's) taking as input the linear objective coefficients, which (1) determines whether the optimal LP solution is achievable by a policy in the given family; and (2) if so, computes a set of class-ranking indices that characterize optimal priority policies in the family. In the special case of project scheduling, we show that, under additional conditions, the optimal indices can be computed separately for each project (index decomposition). We further apply the framework to the important restless bandit model (two-action Markov decision chains), obtaining new index policies, that extend Whittle's (1988), and simple sufficient conditions for their validity. These results highlight the power of polyhedral methods (the so-called achievable region approach) in dynamic and stochastic optimization.

Bundling electronic journals and competition among publishers

Site licensing of e-journals has been revolutionizing the way academicinformation is distributed. However, many librarians are concerned aboutthe possibility that publishers might abuse site licensing by practicingbundling. In this paper, we analyze the private and social incentives forthe publishers to use bundling in the context of STM electronic journalmarket. In the short run in which the number of journals is exogenouslygiven, we find a strong conflict between the two incentives: each publisherfinds bundling optimal and bundling increases the industry profit butreduces social welfare. However, in the long run we find that publishersmight have higher incentives to introduce new journals under bundlingthan without bundling and, in this case, bundling can reduce the industryprofit while increasing social welfare. Finally, we examine publishers incentive to provide links to the websites of the rival publishers underbundling and show that even asymmetric publishers have incentive tointerconnect.

Perceptual mapping of practical ethics along the value chain: A multiple correspondence analysis with industry and cultural indices as supplementary variables

This paper presents findings from a study investigating a firm s ethical practices along the value chain. In so doing we attempt to better understand potential relationships between a firm s ethical stance with its customers and those of its suppliers within a supply chain and identify particular sectoral and cultural influences that might impinge on this. Drawing upon a database comprising of 667 industrial firms from 27 different countries, we found that ethical practices begin with the firm s relationship with its customers, the characteristics of which then influence the ethical stance with the firm s suppliers within the supply chain. Importantly, market structure along with some key cultural characteristics were also found to exert significant influence on the implementation of ethical policies in these firms.

Electronic titling: Potential and risks

Initiatives in electronic conveyancing and registration show the potential of new technologies to transform such systems, reducing costs and enhancing legal security. However,they also incur substantial risks of transferring costs and risks among registries, conveyancersand rightholders, instead of reducing them; entrenching the private interests of conveyancers,instead of increasing competition and disintermediating them; modifying the allocation of tasksin a way that leads in the long term to the debasement of registries of rights with indefeasibletitle into mere recordings of deeds; and empowering conveyancers instead of transactors andrightholders, which increases costs and reduces security. Fulfilling the promise of newtechnologies in both costs and security requires strengthening registries incentives andempowering rightholders in their interaction with registries.

Towards storage and access of electronic theses: A proposal of its organisation for the Consortium of Catalan Libraries

Els objectius d'aquest informe són realitzar un estudi de la tècnica en la digitalització, l'emmagatzematge i l'accés a les tesis doctorals electròniques, per tal de fer una proposta d’organització al Consorci de Biblioteques Universitàries de Catalunya (CBUC). Actualment, tot i que existeixen diverses iniciatives a Europa, és als EUA on la digitalització de tesis doctorals s’ha desenvolupat més amb la creació de la Networked Digital Library for Theses and Dissertation (NDLTD), i ha estat qui ha definit els estàndards en aquest camp. En el següent informe es planteja i es recomana al CBUC l’adhesió institucional a l’NDLTD per poder gaudir de la seva experiència.

Trends in indices of daily precipitation extremes in Catalonia (NE Spain), 1951-2003

The aim of this paper is to quantitatively characterize the climatology of daily precipitation indices in Catalonia (northeastern Iberian Peninsula) from 1951 to 2003. This work has been performed analyzing a subset of the ETCCDI (Expert Team on Climate Change Detection and Indices) precipitation indices calculated from a new interpolated dataset of daily precipitation, namely SPAIN02, regular at 0.2° horizontal resolution (around 20 km) and from two high-quality stations: the Ebro and Fabra observatories. Using a jack-knife technique, we have found that the sampling error of the SPAIN02 regional averaged is relatively low. The trend analysis has been implemented using a Circular Block Bootstrap procedure applicable to non-normal distributions and autocorrelated series. A running trend analysis has been applied to analyze the trend persistence. No general trends at a regional scale are observed, considering the annual or the seasonal regional averaged series of all the indices for all the time windows considered. Only the consecutive dry days index (CDD) at annual scale shows a locally coherent spatial trend pattern; around 30% of the Catalonia area has experienced an increase of around 2¿3 days decade¿1. The Ebro and Fabra observatories show a similar CDD trend, mainly due to the summer contribution. Besides this, a significant decrease in total precipitation (around ¿10 mm decade¿1) and in the index "highest precipitation amount in five-day period" (RX5DAY, around ¿5 mm decade¿1), have been found in summer for the Ebro observatory.

Informe sobre el segon DLM-Forum on electronic records

El DLM-Forum on Electronic Records és un fòrum internacional multidisciplinari, organitzat per la Comissió Europea, que té per objectiu impulsar els projectes per a la millora de la gestió dels documents electrònics en les organitzacions i per a la conservació d'aquests a llarg termini. Al mateix temps, el DLM-Forum esdevé un punt de referència bàsic per a la coordinació de les polítiques de gestió dels documents electrònics que es porten a terme als estats membres de la Unió Europea, per a l'establiment d'estàndards de gestió i de conservació a escala comunitària, i per a la implicació dels agents del sector privat en la recerca de solucions a la problemàtica dels documents electrònics. El present informe exposa l'origen d'aquesta iniciativa, en descriu les dues edicions celebrades fins ara i les perspectives de futur del fòrum.

Electronic thesis and dissertations conference, University of Pittsburgh, 10-12 de junio de 2009

El pasado mes de junio se celebró en Pittsburgh, EE.UU., el duodécimo simposio internacional sobre tesis electrónicas: Electronic Thesis and Dissertations Conference (ETD2009). Fue organizado por Networked Digital Library of Theses and Dissertations (NDLTD). La mayoría de los ponentes explicaron las experiencias de su propia universidad. Además, hubo expertos invitados entre los cuales se pueden destacar Stevan Harnad (Univ. Southampton), Karla Hahn (Association of Research Libraries) y Deanna Marcum (Library of Congress). Estos simposios pretenden promover la adopción, creación, uso, difusión y preservación de las tesis electrónicas. De hecho, el éxito ha sido tal, que algunas universidades ya prescinden de la copia en papel para el depósito y preservación del documento. Un caso reciente es el de la University of Albany cuya nueva política, anunciada durante el simposio, consiste en que a partir de setiembre del 2009 ya no requiere el depósito de una copia impresa de las tesis aprobadas en aquella universidad.

Electronic journals, scholarly communication and libraries

The recent surge in scientific electronic journals began when libraries began having access to the WWW in the mid-1990s. The shift from paper to digital has affected the traditional alignment and role of the primary "stakeholders" -mainly authors, publishers, universities and libraries. The author offers a brief review of the history of the scholarly journal followed by the evolution of e-journals in during the past two decades. The article then focuses on the implications that these have had on traditional library processes and services such as selection, acquisitions, cataloguing, storage, preservation and user services. In the conclusion the author speculates on the long term effect of Web-based publishing on the format of the traditional scholarly journal as it has existed for over 300 years.

Librarians' perceptions on the use of electronic resources at Catalan academic libraries: results of a focus group

The aim of this paper is to expand on previous quantitative and qualitative research into the use of electronic information resources and its impact on the information behaviour of academics at Catalan universities.

A qualitative study of the impact of electronic journals on scholarly information behavior

A qualitative study of the impact of electronic journals on the information behavior of academics at Catalan universities shows that academics now read more, and more widely. However, their reading is becoming more superficial; they are compelled to improve their discrimination skills in order to decide what to read in more depth. The electronic accessibility of journals means that academics now make fewer library visits. Web browsing and TOC e-mail alerts are replacing physical browsing, and searching is a very popular option for keeping up to date with developments. Internet search engines, especially Google and Google Scholar, are becoming important sources of information for academics. However, they face problems in managing their personal scientific information.

Informe sobre el tercer DLM-Forum on Electronic Records (Barcelona, 6¿8 de maig de 2002)

Del 6 al 8 de maig de 2002 es va celebrar a Barcelona la tercera edició del DLM-Forum on Electronic Records, el fòrum internacional multidisciplinari que té per objectiu la millora de la gestió dels documents electrònics a les organitzacions i conservació a llarg termini. Aquesta edició ha estat marcada per una participació més activa de la indústria de les tecnologies de la informació i de les comunicacions, i per la presentació dels resultats d'iniciatives del DLM-Forum 1996. El present informe descriu la gènesi i el desenvolupament del DLM-Forum de Barcelona, i n'indica els assoliments més remarcables.

Static dipole polarizability of alkali-metal clusters: Electronic exchange and correlation effects

Nonlocal approximations for the electronic exchange and correlation effects are used to compute, within density-functional theory, the polarizability and surface-plasma frequencies of small jelliumlike alkali-metal clusters. The results are compared with those obtained using the local-density approximation and with available experimental data, showing the relevance of these effects in obtaining an accurate description of the surface response of metallic clusters.

Electronic structure of few-electron concentric double quantum rings

The ground state structure of few-electron concentric double quantum rings is investigated within the local spin density approximation. Signatures of inter-ring coupling in the addition energy spectrum are identified and discussed. We show that the electronic configurations in these structures can be greatly modulated by the inter-ring distance: At short and long distances the low-lying electron states localize in the inner and outer rings, respectively, and the energy structure is essentially that of an isolated single quantum ring. However, at intermediate distances the electron states localized in the inner and the outer ring become quasidegenerate and a rather entangled, strongly-correlated system is formed.