Inter-group conflict and intra-group punishment in an experimental contest game

We study how conflict in a contest game is influenced by rival parties being groups and by group members being able to punish each other. Our main motivation stems from the analysis of socio-political conflict. The relevant theoretical prediction in our setting is that conflict expenditures are independent of group size and independent of whether punishment is available or not. We find, first, that our results contradict the independence of group-size prediction: conflict expenditures of groups are substantially larger than those of individuals, and both are substantially above equilibrium. Towards the end of the experiment material losses in groups are 257% of the predicted level. There is, however, substantial heterogeneity in the investment behaviour of individual group members. Second, allowing group members to punish each other after individual contributions to the contest effort are revealed leads to even larger conflict expenditures. Now material losses are 869% of the equilibrium level and there is much less heterogeneity in individual group members' investments. These results contrast strongly with those from public goods experiments where punishment enhances efficiency and leads to higher material payoffs.

Stock market volatility and learning

Introducing bounded rationality in a standard consumption-based asset pricing model with time separable preferences strongly improves empirical performance. Learning causes momentum and mean reversion of returns and thereby excess volatility, persistence of price-dividend ratios, long-horizon return predictability and a risk premium, as in the habit model of Campbell and Cochrane (1999), but for lower risk aversion. This is obtained, even though our learning scheme introduces just one free parameter and we only consider learning schemes that imply small deviations from full rationality. The findings are robust to the learning rule used and other model features. What is key is that agents forecast future stock prices using past information on prices.

Vitamin D deficiency and a CYP27B1-1260 promoter polymorphism are associated with chronic hepatitis C and poor response to interferon-alfa based therapy

BACKGROUND: Vitamin D is an important immune modulator and preliminary data indicated an association between vitamin D deficiency and sustained virologic response (SVR) rates in patients with chronic hepatitis C. We therefore performed a comprehensive analysis on the impact of vitamin D serum levels and of genetic polymorphisms within the vitamin D cascade on chronic hepatitis C and its treatment. METHODS: Vitamin D serum levels, genetic polymorphisms within the vitamin D receptor and the 1α- hydroxylase were determined in a cohort of 468 HCV genotype 1, 2 and 3 infected patients who were treated with interferon-alfa based regimens. RESULTS: Chronic hepatitis C was associated with a high incidence of severe vitamin D deficiency compared to controls (25(OH)D3<10 ng/mL in 25% versus 12%, p<0.00001), which was in part reversible after HCV eradication. 25(OH)D3 deficiency correlated with SVR in HCV genotype 2 and 3 patients (63% and 83% SVR for patients with and without severe vitamin D deficiency, respectively, p<0.001). In addition, the CYPB27-1260 promoter polymorphism rs10877012 had substantial impact on 1-25- dihydroxyvitamin D serum levels and SVR rates in HCV genotype 1, 2 and 3 infected patients. CONCLUSIONS: Chronic hepatitis C virus infection is associated with vitamin D deficiency. Reduced 25- hydroxyvitamin D levels and CYPB27-1260 promoter polymorphism are associated with failure to achieve SVR in HCV genotype 1, 2, 3 infected patients.

The Export Base Model with a Supply-Side Stimulus to the Export Sector

Paper delivered at the Western Regional Science Association Annual Conference, Sedona, Arizona, February, 2010.

Comparing the early research performance of PhD graduates in labor economics in Europe and the USA

This paper analyzes the early research performance of PhD graduates in labor economics, addressing the following questions: Are there major productivity differences between graduates from American and European institutions? If so, how relevant is the quality of the training received (i.e. ranking of institution and supervisor) and the research environment in the subsequent job placement institution? The population under study consists of labor economics PhD graduates who received their degree in the years 2000 to 2005 in Europe or the USA. Research productivity is evaluated alternatively as the number of publications or the quality-adjusted number of publications of an individual. When restricting the analysis to the number of publications, results suggest a higher productivity by graduates from European universities than from USA universities, but this difference vanishes when accounting for the quality of the publication. The results also indicate that graduates placed at American institutions, in particular top ones, are likely to publish more quality-adjusted articles than their European counterparts. This may be because, when hired, they already have several good acceptances or because of more focused research efforts and clearer career incentives.

Trends in economic research: an international perspective

Given the recent efforts in several countries to reorganize the research institutional setting to improve research productivity, our analysis addresses the following questions: To which extent has the recent awareness over international quality standards in economics around the world been reflected in research performance? How have individual countries fared? Do research quantity and quality indicators tell us the same story? We concentrate on trends taking place since the beginning of the 1990s and rely on a very comprehensive database of scientific journals, to provide a cross-country comparison of the evolution of research in economics. Our findings indicate that Europe is catching-up with the US but, in terms of influential research, the US maintains a dominant position. The main continental European countries, Germany, France, Italy and Spain, experienced some of the largest growth rates in economic scientific output. Other European countries, namely the UK, Norway, the Netherlands, Denmark, and Sweden, have shown remarkable progress in per capita output. Collaborative research seems to be a key factor explaining the relative success of some European countries, in particular when it comes to publishing in top journals, attained predominantly through international collaborations.

A right to a national space of communication? : on Stateless nations, their right to a space of communication of their own

Hem establert les bases metodològiques i teòriques per investigar la pregunta “Tenen les nacions sense estat el dret de controlar el seu propi espai de comunicació?”. La investigació ajusta el concepte d’espai de comunicació a la teoria política, cercant els seus límits en els drets individuals i, des de la perspectiva del liberalisme 2, aportant la justificació del seu control en quant que plataforma que incideix en la conservació i supervivència d’una cultura nacional. El primer article i fase de la tesi és l’adaptació i definició del concepte espai de comunicació. Fins ara, la recerca ha proposat diferents models d’espai de comunicació entenent si es tracta d’una visió emfatitzant la distribució i la producció de material marcat amb els símbols de la identitat nacional de la societat emissora, o bé si emfatitza la idea d’un espai de circulació de fluxos comunicatiu ajustat a un territori tradicionalment vinculat a una identitat nacional o nació sense estat. Igualment, es distingeix la dimensió d’emissió –sortir del territori al món- i la de recepció –fluxos informatius rebuts des del món al territori, concretament, al ciutadà; el paper d’intervenció de les institucions democràtiques és diferent en una dimensió o una altra i, per tant, també són diferents els drets afectats i les teories o principis que neguen o justifiquen el control de l’espai de comunicació. També s’ha indagat en les teories sobre els efectes cognitius dels mitjans de comunicació per relacionar-los amb la construcció nacional com a cohesió simbòlica i cultural. Si bé els mitjans no poden fer canviar de pensament immediatament, sí que poden conformar a llarg termini una percepció nacional general. Una comunitat és imaginada, donada la distància física dels seus components, i la comunicació social és, juntament amb l’educació, el principal factor de construcció nacional, avui en dia.

Interleukin-4 and interleukin-5 as targets for the inhibition of eosinophilic inflammation and allergic airways hyperreactivity

Clinical and experimental investigations suggest that allergen-specific CD4+ T-cells, IgE and the cytokines IL-4 and IL-5 play central roles in initiating and sustaining an asthmatic response by regulating the recruitment and/or activation of airways mast cells and eosinophils. IL-5 plays a unique role in eosinophil development and activation and has been strongly implicated in the aetiology of asthma. The present paper summarizes our recent investigations on the role of these cytokines using cytokine knockout mice and a mouse aeroallergen model. Investigations in IL-5-/- mice indicate that this cytokine is critical for regulating aeroallergen-induced eosinophilia, the onset of lung damage and airways hyperreactivity during allergic airways inflammation. While IL-4 and allergen-specific IgE play important roles in the regulation of allergic disease, recent investigations in IL4-/- mice suggest that allergic airways inflammation can occur via pathways which operate independently of these molecules. Activation of these IL-4 independent pathways are also intimately associated with CD4+ T-cells, IL-5 signal transduction and eosinophilic inflammation. Such IL-5 regulated pathways may also play a substantive role in the aetiology of asthma. Thus, evidence is now emerging that allergic airways disease is regulated by humoral and cell mediated processes. The central role of IL-5 in both components of allergic disease highlights the requirements for highly specific therapeutic agents which inhibit the production or action of this cytokine.

The role of interleukin-5 (IL-5 ) in vivo: studies with IL-5 deficient mice

Eosinophil recruitment is a characteristic feature of a number of pathological conditions and was the topic of the recent International Symposium on allergic inflammation, asthma, parasitic and infectious diseases (Rio de Janeiro, June 3-5, 1996). Since interleukin5 (IL5) is believed to regulate the growth, differentiation and activation of eosinophils (Coffman et al. 1989, Sanderson 1992), the role of eosinophils and IL5 are closely linked. Although IL5 specifically regulates eosinophilia in vivo and this is its most well established activity, it is becoming clear that IL5 also has other biological effects. The recent derivation of an IL5 deficient mouse (Kopf et al. 1996), provides a model for exploring not only the role of IL5 and eosinophils but also other novel activities of IL5. Of note is that although the IL5 deficient mice cannot elicit a pronounced eosinophilia in response to inflammatory stimulation following aeroallergen challenge or parasite infection they still produce basal levels of eosinophils that appear to be morphologically and functionally normal. However, the basal levels of eosinophils appear insufficient for normal host defence as IL5 deficiency has now been shown to compromise defence against several helminth infections. In addition, IL5 deficient mice appear to have functional deficiencies in B-1 B lymphocytes and in IgA production.

Local and global consistency properties for student placement

In the context of resource allocation on the basis of priorities, Ergin (2002) identifies a necessary and sufficient condition on the priority structure such that the student-optimal stable mechanism satisfies a consistency principle. Ergin (2002) formulates consistency as a local property based on a fixed population of agents and fixed resources -- we refer to this condition as local consistency and to his condition on the priority structure as local acyclicity. We identify a related but stronger necessary and sufficient condition (unit acyclicity) on the priority structure such that the student-optimal stable mechanism satisfies a more standard global consistency property. Next, we provide necessary and sufficient conditions for the student-optimal stable mechanism to satisfy converse consistency principles. We identify a necessary and sufficient condition (local shift-freeness) on the priority structure such that the student-optimal stable mechanism satisfies local converse consistency. Interestingly, local acyclicity implies local shift-freeness and hence the student-optimal stable mechanism more frequently satisfies local converse consistency than local consistency. Finally, in order for the student-optimal stable mechanism to be globally conversely consistent, one again has to impose unit acyclicity on the priority structure. Hence, unit acyclicity is a necessary and sufficient condition on the priority structure for the student-optimal stable mechanism to satisfy global consistency or global converse consistency.