On the computational security of a distributed key distribution scheme

In a distributed key distribution scheme, a set of servers helps a set of users in a group to securely obtain a common key. Security means that an adversary who corrupts some servers and some users has no information about the key of a noncorrupted group. In this work, we formalize the security analysis of one such scheme which was not considered in the original proposal. We prove the scheme is secure in the random oracle model, assuming that the Decisional Diffie-Hellman (DDH) problem is hard to solve. We also detail a possible modification of that scheme and the one in which allows us to prove the security of the schemes without assuming that a specific hash function behaves as a random oracle. As usual, this improvement in the security of the schemes is at the cost of an efficiency loss.

Opportunities for a cultural specific approach in the computational description of music

The current research in Music Information Retrieval (MIR) is showing the potential that the Information Technologies can have in music related applications. Amajor research challenge in that direction is how to automaticallydescribe/annotate audio recordings and how to use the resulting descriptions to discover and appreciate music in new ways. But music is a complex phenomenonand the description of an audio recording has to deal with this complexity. For example, each musicculture has specificities and emphasizes different musicaland communication aspects, thus the musical recordings of each culture should be described differently. At the same time these cultural specificities give us the opportunity to pay attention to musical concepts andfacets that, despite being present in most world musics, are not easily noticed by listeners. In this paper we present some of the work done in the CompMusic project, including ideas and specific examples on how to take advantage of the cultural specificities of differentmusical repertoires. We will use examples from the art music traditions of India, Turkey and China.

Predictors of political orientation among US-born Mexican Americans: cultural identification, acculturation attitudes and socioeconomic status

With each passing election, U.S. political campaigns have renewed their efforts in courting the “Latino vote,” yet the Latino population is not a culturally homogenous voting bloc. This study examined how cultural identifications and acculturation attitudes in U.S. born Mexican Americans interacted with socioeconomic status (SES) to predict political orientation. Individuals who held stronger Mexican identity and supported biculturalism as an acculturation strategy had a more liberal orientation, while belonging to a higher SES group and holding stronger assimilation attitudes predicted a less liberal orientation. Mexican cultural identification interacted with SES such that those who held a weaker Mexican identity, but came from a higher social class were less liberal and more moderate in their political orientation. Weak Mexican identification and higher SES also predicted weaker endorsement of bicultural acculturation attitudes, which in turn, mediated the differences in political orientation. The acceptance of one’s ethnic identity and endorsement of bicultural attitudes predicted a more liberal political orientation. In light of these findings, political candidates should be cautious in how they pander to Latino constituents—referencing the groups’ ethnic culture or customs may distance constituents who are not strongly identified with their ethnic culture.

Intertwined cultural demands of immigrants and minority nations

Since at least the last two decades of the 20th century, the normative debate on multiculturalism has been one-dimensional. It has deployed arguments related to cultural demands either linked to feminism and sub-cultural identities, immigration or national minorities. Little attention has been given to the relations between these dimensions, and how they effect each other in putting forward demands to the nation-state. The purpose of this article is to analyse the interaction between cultural demands of immigrants and minority nations. The basic objective of this paper is to give an overview of different reflections coming from three basic contributors: J. Carens, W. Kymlicka and R. Bauböck.

Redefinición del espectador cinematográfico en relación al audiovisual contemporáneo. Un nuevo agente en la producción cultural

El cine se enfrenta, hoy, a múltiples retos en su propia configuración, acompañando un frenético desarrollo tecnológico. Se ha convertido en matriz de la multiplicación audiovisual contemporánea. En este contexto es preciso redefinir al espectador como sujeto que encarna hoy nuevas funciones y ocupa espacios variados en el conjunto de la producción cultural.Se apuesta por una redefinición del espectador cinematográfico en relación a la evolución del audiovisual digital -sus implicaciones tecnológicas y narrativas- y la relación de ambos con las instituciones de la producción cultural contemporánea -sus políticas de acceso y estrategias de adaptación-.Esta aproximación se fundamenta en el reconocimiento de la capacidad productiva de este nuevo agente cultural y las correspondencias que esta evolución implica respecto al panorama audiovisual contemporáneo.

Pot modificar un canvi urbanístic l'economia d'un barri? : El cas de Ciutat Vella i el cluster cultural

Tots hem sentit a parlar del canvi del Raval en aquests últims anys. Actualment la majoria del jovent no només hi estudia sinó que hi passa la major part del seu tempsd’oci, en bars, restaurants, museus, galeries d’art, comerços...Nosaltres ens hem preguntat: Per què el Raval ha canviat tant? S’han fet molts treballs, molts estudis, s’han intentat trobar les diverses causes que han produït aquest fenòmen.Més específicament ens hem preguntat: Pot ser que degut a la construcció del cluster cultural format pel MACBA i el CCCB, entre d’altres, s’hagi produït aquest canvi?Així doncs, en aquest treball intentarem contestar ambdues preguntes. Intentarem ser precisos, concisos, breus i clars; esperem que us resulti interessant.

Social Security in Theory and Practice (II): Efficiency Theories, Narrative Theories, and Implications for Reform

166 countries have some kind of public old age pension. What economic forces create and sustain old age Social Security as a public program? Mulligan and Sala-i-Martin (1999b) document several of the internationally and historically common features of social security programs, and explore "political" theories of Social Security. This paper discusses the "efficiency theories", which view creation of the SS program as a full of partial solution to some market failure. Efficiency explanations of social security include the "SS as welfare for the elderly" the "retirement increases productivity to optimally manage human capital externalities", "optimal retirement insurance", the "prodigal father problem", the "misguided Keynesian", the "optimal longevity insurance", the "government economizing transaction costs", and the "return on human capital investment". We also analyze four "narrative" theories of social security: the "chain letter theory", the "lump of labor theory", the "monopoly capitalism theory", and the "Sub-but-Nearly-Optimal policy response to private pensions theory". The political and efficiency explanations are compared with the international and historical facts and used to derive implications for replacing the typical pay-as-you-go system with a forced savings plan. Most of the explanations suggest that forced savings does not increase welfare, and may decrease it.

Organisational Values as "Attractors of Chaos": An Emerging Cultural Change to Manage Organisational Complexity

Business organisations are excellent representations of what in physics and mathematics are designated "chaotic" systems. Because a culture of innovation will be vital for organisational survival in the 21st century, the present paper proposes that viewing organisations in terms of "complexity theory" may assist leaders in fine-tuning managerial philosophies that provide orderly management emphasizing stability within a culture of organised chaos, for it is on the "boundary of chaos" that the greatest creativity occurs. It is argued that 21st century companies, as chaotic social systems, will no longer be effectively managed by rigid objectives (MBO) nor by instructions (MBI). Their capacity for self-organisation will be derived essentially from how their members accept a shared set of values or principles for action (MBV). Complexity theory deals with systems that show complex structures in time or space, often hiding simple deterministic rules. This theory holds that once these rules are found, it is possible to make effective predictions and even to control the apparent complexity. The state of chaos that self-organises, thanks to the appearance of the "strange attractor", is the ideal basis for creativity and innovation in the company. In this self-organised state of chaos, members are not confined to narrow roles, and gradually develop their capacity for differentiation and relationships, growing continuously toward their maximum potential contribution to the efficiency of the organisation. In this way, values act as organisers or "attractors" of disorder, which in the theory of chaos are equations represented by unusually regular geometric configurations that predict the long-term behaviour of complex systems. In business organisations (as in all kinds of social systems) the starting principles end up as the final principles in the long term. An attractor is a model representation of the behavioral results of a system. The attractor is not a force of attraction or a goal-oriented presence in the system; it simply depicts where the system is headed based on its rules of motion. Thus, in a culture that cultivates or shares values of autonomy, responsibility, independence, innovation, creativity, and proaction, the risk of short-term chaos is mitigated by an overall long-term sense of direction. A more suitable approach to manage the internal and external complexities that organisations are currently confronting is to alter their dominant culture under the principles of MBV.

Art i part :la figura del/la professional de l'educació social en processos de desenvolupament cultural comunitari

Anàlisi de la figura de l'educador/a social en processos de desenvolupament comunitari a partir d'experiències diverses a Catalunya

Market versus limit orders in an imperfectly competitive security

This paper analyzes the choice between limit and market orders in animperfectly competitive noisy rational expectations economy. There is a uniqueinsider, who takes into account the effect their trading has on prices. If theinsider behaves as a price taker, she will choose market orders if her privateinformation is very precise and she will choose limit orders otherwise. On thecontrary, if the insider recognizes and exploits her ability to affect themarket price, her optimal choice is to place limit orders whatever the precisionof her private information.

On the cultural transmission of corruption

We provide a cultural explanation to the phenomenon of corruption in the framework of an overlapping generations model with intergenerational transmissionof values. We show that the economy has two steady states with different levels of corruption. The driving force in the equilibrium selection process is the education effort exerted by parents which depends on the distribution of ethics in the population and on expectations about future policies. We propose some policy interventions which via parents' efforts have long-lasting effects on corruption and show the success of intensive education campaigns. Educating the young is a key element in reducing corruption successfully.

Social security, retirement, and the single-mindedness of the electorate

We propose a positive theory that is consistent with two important featuresof social security programs around the world: (1) they redistributeincome from young to old and (2) they induce retirement. We construct avoting model that includes a political campaign or debate prior to theelection. The model incorporates single-mindedness of the groups that donot work: while the workers divide their political capital between their age concerns and occupational concerns , the retired concentrate alltheir political capital to support their age group. In our model, theelderly end up getting transfers from the government (paid by the young)and distortionary labor income taxes induce the retirement of the elderly.In addition, our model predicts that occupational groups that work morewill tend to have more political power. The opposite is true fornon-occupational groups (such as the elderly). We provide some evidencethat supports these additional predictions.

Social security in theory and practice (II): Efficiency theories, narrative theories and implications for reform

166 countries have some kind of public old age pension. What economic forcescreate and sustain old age Social Security as a public program? Mulligan and Sala-i-Martin (1999b) document several of the internationally and historically common features of social security programs, and explore "political" theories of Social Security. This paper discusses the "efficiency theories", which view creation of the SS program as a full of partial solution to some market failure. Efficiency explanations of social security include the "SS as welfare for the elderly" the "retirement increases productivity to optimally manage human capital externalities", "optimal retirement insurance", the "prodigal father problem", the "misguided Keynesian", the "optimal longevity insurance", the "governmenteconomizing transaction costs", and the "return on human capital investment". We also analyze four "narrative" theories of social security: the "chain letter theory", the "lump of labor theory", the "monopoly capitalism theory", and the "Sub-but-Nearly-Optimal policy response to private pensions theory".The political and efficiency explanations are compared with the international and historical facts and used to derive implications for replacing the typical pay-as-you-go system with a forced savings plan. Most of the explanations suggest that forced savings does not increase welfare, and may decrease it.