José E. Vila

Computational Complexity and Communication: Coordination in Two-Player Games

The main contribution of this paper is the development and application of cryptographic techniques to the design of strategic communication mechanisms. One of the main assumptions in cryptography is the limitation of the computational power available to agents. We introduce the concept of limited computational complexity, and by borrowing results from cryptography, we construct a communication protocol to establish that every correlated equilibrium of a two-person game with rational payoffs can be achieved by means of computationally restricted unmediated communication. This result provides an example in game theory where limitations of computational abilities of players are helpful in solving implementation problems. More specifically, it is possible to construct mechanisms with the property that profitable deviations are too complicated to compute. Copyright The Econometric Society 2002.

An entrepreneur's social capital and performance: The role of access to information in the Argentinean case

Purpose - The aim of this paper is to analyze the impact of an entrepreneurs social capital on their access to information, and how such access improves the performance of their entrepreneurial project. Design/methodology/approach - A structural equations model (SEM) is estimated and validated from a database including information from 282 Argentinean entrepreneurs who answered a questionnaire specifically designed for this research. The analysis of this model allowed the impact of dependent latent variables on the performance of the start-up to be determined. Findings - The performance of an entrepreneurial project depends on an entrepreneurs access to finance, markets and information. Specific dimensions of social capital facilitate access to these resources: the relational dimension facilitates access to information; the resources dimension makes access to finance easier; the structural dimension helps the entrepreneur to access markets. Research limitations/implications - The sample is not large enough to analyze differences among specific types of entrepreneurial projects: for instance, the role of social capital in industrial and service entrepreneurship (activity sector), the differences between the federal capital, Buenos Aires, and the rest of the country (location), and between female and male entrepreneurs (gender). Originality/value - The results help in understanding which dimensions of an entrepreneurs social capital facilitate access to information and how these specific dimensions enhance the performance of the project. Hence, this paper has managerial and policy implications for the generation of dynamic entrepreneurial projects capable of becoming development drivers.

4-Hydroxynonenal, a Lipid Peroxidation Product, Induces Relaxation of Human Cerebral Arteries

The relaxant effect of 4-hydroxynonenal (4-HNE), a lipid peroxidation product, on human cerebral arteries was studied. Addition of 4-HNE to artery rings promoted no contraction, and after stimulation with prostaglandin F2α (PFG2α; 10−7-3 × 10−6 M), 100% relaxation was obtained with 3 × 10−5 M 4-HNE. Inhibition of nitric oxide formation with NG-nitro-l-arginine methyl ester hydrochloride (l-NAME; (10−4 M), as well as prostaglandin synthesis with indomethacin (3 × 10−6 M), partially prevented 4-HNE-induced relaxation, but each of these substances separately failed to inhibit complete relaxation. Addition of both inhibitors together reduced 4-HNE-induced relaxation to ≈50%, but relaxation could not be abolished. When the endothelium was removed, 4-HNE did not promote relaxation after PGF2α stimulation. The possible roles of different intracellular signaling systems in the vascular effect of 4-HNE are discussed.

Sugammadex, a neuromuscular blockade reversal agent, causes neuronal apoptosis in primary cultures.

Sugammadex, a γ-cyclodextrin that encapsulates selectively steroidal neuromuscular blocking agents, such as rocuronium or vecuronium, has changed the face of clinical neuromuscular pharmacology. Sugammadex allows a rapid reversal of muscle paralysis. Sugammadex appears to be safe and well tolerated. Its blood-brain barrier penetration is poor (< 3% in rats), and thus no relevant central nervous toxicity is expected. However the blood brain barrier permeability can be altered under different conditions (i.e. neurodegenerative diseases, trauma, ischemia, infections, or immature nervous system). Using MTT, confocal microscopy, caspase-3 activity, cholesterol quantification and Western-blot we determine toxicity of Sugammadex in neurons in primary culture. Here we show that clinically relevant sugammadex concentrations cause apoptotic/necrosis neuron death in primary cultures. Studies on the underlying mechanism revealed that sugammadex-induced activation of mitochondria-dependent apoptosis associates with depletion of neuronal cholesterol levels. Furthermore SUG increase CytC, AIF, Smac/Diablo and CASP-3 protein expression in cells in culture. Potential association of SUG-induced alteration in cholesterol homeostasis with oxidative stress and apoptosis activation occurs. Furthermore, resistance/sensitivity to oxidative stress differs between neuronal cell types.

Unmediated Communication In Repeated Games With Imperfect Monitoring

We show that any correlated equilibrium payoff of two-player repeated games with imperfect monitoring and without discounting can be reached as the Nash equilibrium payoff of the game extended by a universal mechanism of unmediated communication. This result holds regardless the particular concept of equlibrium involved (upper, lower, Banach or uniform equlibrium). The communication mechanism is built up by using commutative one-way functions. These functions are designed with the help of cryptographic tools.

Are social and entrepreneurial attitudes compatible?: A behavioral and self‐perceptional analysis

Purpose – The aim of this paper is to analyze the compatibility between entrepreneurial and social attitudes. Specifically, we analyze if subjects with a more developed economic entrepreneurial attitude exhibit a less social attitude. Design/methodology/approach – Our methodology integrates an economic experimental approach with a standard entrepreneurial intention questionnaire to analyze the interaction between entrepreneurial and social self-perceptions and behavior. Findings – There is empirical evidence that experimental entrepreneurial behavior (characterized by detecting an opportunity and accepting risk to take an economic advantage from it in laboratory experiments) reduces the incentive for social behavior. However, this effect does not appear if just self-perceptions instead of experimental behaviors are considered. Research limitations/implications – The social attitude of entrepreneurs may be overestimated in those empirical research studies based only on data obtained from entrepreneurs’ answers to hypothetical questions in a survey. Originality/value - To the best of our knowledge, this is the first paper presenting a laboratory experiment to represent the key features of entrepreneurial behavior instead of a case-control analysis to set differences in the experimental behavior of sub-samples of subjects defined in terms of their entrepreneurial motivation or experience.

Guanxi, performance and innovation in entrepreneurial service projects

This paper analyzes the role played by two dimensions of entrepreneurs’ private social capital in the survival, growth and innovativeness of entrepreneurial service ventures: local size and preferential attachment degree. We build a bi-dimensional measure of social capital based on network models and a methodology to estimate this measure for any group of entrepreneurs. Based on a survey of service entrepreneurs who launched their business in the city of Shanghai, we show that roles played by each dimension are quite different. A large local size of the network increases the chances of survival of the new venture. However, the chance to become a dynamic venture is only related to entrepreneurs’ preferential attachment degree. This finding has relevant political and managerial implications.

What are the relationships among Web 2.0, market orientation and innovativeness?

Purpose – Firms are adopting Web 2.0 technologies to improve collaboration, participation and communication; however there are few empirical studies testing the impact of this adoption. The purpose of this article is to analyze if there is a linkage amongst market orientation, Web 2.0 adoption and innovativeness.Design/methodology/approach – Structural equation modeling was used to test the relationships amongst the variables. A sample of 244 firms of the hospitality industry was used. The theoretical approach is based on the market orientation and innovativeness, concepts, which have been studied by various authors in the literature.Findings – A positive relationship was found between market orientation and Web 2.0 adoption and between Web 2.0 adoption and innovativeness.Research limitations/implications – The study was developed in one industry, so in order to generalize the findings, additional testing in other industries should be developed. In addition a longitudinal study is encouraged.Practical imp...

Multidimensional social capital in new ventures

This paper analyzes and provides empirical evidence on how three different dimensions of social capital (structural, relational, and resources) have a direct causal relation on the performance of financial service start-ups. To this end, a structural equation model is estimated and validated from a database, including information from 142 Argentinean entrepreneurs who answered a questionnaire specifically designed for this research. The main finding of the paper is that the main source of value of social capital for an entrepreneur is the existence of high-quality links. Moreover, the quality of the entrepreneurs links is even more important than their quantity. This conclusion has relevant managerial and policy implications, since it suggests that entrepreneurs must focus their efforts not so much on increasing their number of contacts, but on establishing, developing, and enhancing a small number of high-quality links.

Modelling Farmers’ Behaviour Toward Risk in a Large Scale Positive Mathematical Programming (PMP) Model

Agricultural production is characterized for being a risky business due to weather variability, market instability, plant diseases as well as climate change and political economy uncertainty. The modelling of risk at farm level is not new, however, the inclusion of risk in Positive Mathematical Programming (PMP) models is particularly challenging. Most of the few existing PMP-risk approaches have been conducted at farm-type level and for a very limited and specific sample of farms. This implies that the modelling of risk and uncertainty at individual farm level and in a large scale system is still a challenging task. The aim of this paper is to formulate, estimate and test a robust methodology for explicitly modelling risk to be incorporated in an EU-wide individual farm model for Common Agricultural Policy (CAP) analysis, named IFM-CAP. Results show that there is a clear trade-off between the behavioural model (BM) and the behavioural risk model (BRM). Albeit the results show that both alternatives provide very close estimates, the latter increases three times the computation time required for estimation. Despite this, we are convinced that the modelling of risk is crucial to better understand farmer behaviour and to accurately evaluate the impacts of risk management related policies (i.e. insurance schemes).