A Model of ethnic conflict

We present a model of conflict, in which discriminatory government policy or social intolerance is responsive to various forms of ethnic activism, including violence. It is this perceived responsiveness -captured by the probability that the government gives in and accepts a proponed change in ethnic policy- that induces individuals to mobilize in support for their cause. Yet, mobilization is costly and demonstrators have to be compensated accordingly. Individuals have to weigh their ethnic radicalism with their material well-being to determine the size of their money contribution to the cause. Our main results are: (i) a one-sided increase in radicalism or in population size increases conflict; (ii) a one-sided increase in income has ambiguous effects depending on the elasticity of contributions to income; (iii) an increase in within-group inequality increases conflict; and (iv) an increase in the correlation between ethnic radicalism and inequality also increases conflict.

The Social contract with endogenous sentiments

Moral values infuence individual behavior and social interactions. A specially signif- cant instance is the case of moral values concerning work e¤ort. Individuals determine what they take to be proper behaviour and judge the others, and themselves, accordingly. They increase their esteem -and self-esteem- for those who perform in excess of the standard and decrease their esteem for those who work less. These changes in self-esteem result from the self-regulatory emotions of guilt or pride extensively studied in Social Psychology. We examine the interactions between sentiments, individual behaviour and the social contract in a model of rational voting over redistribution where individual self-esteem and relative es-teem for others are endogenously determined. Individuals di¤er in their productivities. The desired extent of redistribution depends both on individual income and on individual attitudes toward others. We characterize the politico-economic equilibria in which sentiments, labor supply and redistribution are simultaneously determined. The model has two types of equilibria. In "cohesive" equilibria, all individuals conform to the standard of proper behav- iour, income inequality is low and social esteem is not biased toward any particular type. Under these conditions equilibrium redistribution increases in response to larger inequality. In a "clustered" equilibrium skilled workers work above the mean while unskilled workers work below. In such an equilibrium, income inequality is large and sentiments are biased in favor of the industrious. As inequality increases, this bias may eventually overtake the egoistic demand for greater taxation and equilibrium redistribution decreases. The type of equilibrium that emerges crucially depends on inequality. We contrast the predictions of the model with data on inequality, redistribution, work values and attitudes toward work and toward the poor for a set of OECD countries.

Polarization, fractionalization and conflict

A recent upsurge of empirical studies on the causes of conflict attempts to connect various features of the distribution of the relevant characteristic (typically ethnicity or religion) to conflict. The distributional indices differ (polarization, fractionalization or Lorenz-domination) and so do the various specifications of "conflict" (onset, incidence or intensity). Overall, the results are far from clear, and combined with the mixture of alternative indices and notions of "conflict" it is not surprising that the reader may come away thoroughly perplexed. The aim of this paper is to provide a theoretical framework that permits us to distinguish between the occurrence of conflict and its severity and that clarifies the role of polarization and fractionalization in each of these cases.

Observaciones sobre la ecología de Lutzomyia longipalpis (Lutz & Neiva, 1912) y posibilidades de existencia de leishmaniasis visceral en Costa Rica

Se describe un área semiárida del noroeste de Costa Rica en donde Lutzomyia longipalpis es abundante en los corrales alrededor de los domicilios. Las capturas mensuales durante dos anõs consecutivos sobre diversos cebos, mostraron que las hembras se alimentan ávidamente de vacuno, caballo, cerdo, perro y humano. De un de 14.215 ejemplares capturados el 90.5% eran machos y la abundancia de la especie fue mayor en los meses más secos, disminuyendo la población notablemente en la época lluviosa. Se discute la posibilidad de que las leishmaniasis visceral pueda establecerse en la zona en el futuro, em forma similar a como sucede en otros países centroamericanos, aunque la enfermedad es aún desconocida en Costa Rica.

Disseny i aplicació del protocol d'instal·lació d'energia fotovoltaica en edificis aïllats de la xarxa elèctrica al PNAP

En el perímetre del parc es troben gran nombre d’edificacions amb mancances de subministrament elèctric per la gran dispersió de la població de la comarca. L’objectiu d’aquest estudi és desenvolupar un protocol per determinar la viabilitat de l’energia fotovoltaica en edificis aïllats i aplicar-la de forma pilot a dos edificis gestionats pels responsables del Parc Natural de l’Alt Pirineu: el Centre de Logística i Manteniment (CLM) i el Refugi del Fornet. Aquests han estat escollits per la seva representativitat com a edificis aïllats de la xarxa elèctrica convencional. S’ha elaborat una metodologia pròpia, el Protocol d’instal·lació d’energia fotovoltaica en edificis aïllats de la xarxa elèctrica. S’ha realitzat una anàlisi de sensibilitats del dimensionat fotovoltaic davant la modificació de diversos paràmetres rellevants. Això ha permès determinar les característiques òptimes de viabilitat per als dos edificis en estudi i el cost de la instal·lació fotovoltaica (17.183€ el CLM i 164.815 € el Refugi del Fornet). Els resultats obtinguts en els dos edificis pilot han mostrat el gran cost relatiu entre l’energia fotovoltaica i l’energia elèctrica produïda a partir de combustibles fòssils.

Arquitectura wormhole per a una NoC 2D-Mesh

Aquest projecte presenta la implementació d'un disseny, i la seva posterior síntesi en una FPGA, d'una arquitectura de tipus wormhole packet switching per a una infraestructura de NetWork-On-Chip amb una topologia 2D-Mesh. Agafant un router circuit switching com a punt de partida, s'han especificat els mòduls en Verilog per tal d'obtenir l'arquitectura wormhole desitjada. Dissenyar la màquina de control per governar els flits que conformen els paquets dins la NoC,i afegir les cues a la sortida del router (outuput queuing) són els punts principals d'aquest treball. A més, com a punt final s'han comparat ambdues arquitectures de router en termes de costos en àrea i en memòria i se n’han obtingut diverses conclusions i resultats experimentals.

Avaluació dels algorismes d'encaminament per a una NoC amb topologia Mesh 2D

Aquest projecte presenta una avaluació de les diferents alternatives d'encaminament per a una NoC amb una topologia mesh 2D. Per tal d'exposar aquestes alternatives s'ha estudiat la composició d'un router implementat amb l'algorisme determinista XY i s'ha adaptat per tal que aquest suportés els algorismes parcialment adaptatius West First, North Last i Negative First. Un cop tenim els routers implementats es disposa un estudi dels diferents algorismes i com cadascun d'aquests actuen en front uns mateixos estímuls per tal de crear una comparativa entre ells que ens faciliti una elecció a priori.

Ecology of sandflies (Diptera: Psychodidae) in a restricted focus of cutaneous leishmaniasis in Northern Venezuela: II. Species composition in relation to habitat, catching method and hour of catching

The ecology of phlebotomine sandflies in an endemic focus of cutaneous leishmaniasis in Northern Venezuela (San Esteban, Carabobo State) was investigated through a year-term study. Three different habitats: viz. a house, a pridomestic area and a sylvatic area, were covered and the species composition, the abundance and occurrence of each species were analyzed in relation to the habitats, catching methods and hour of catching. L. panamensis, L. gomezi and L. ovallesi are the species which bite man, although almost exclusively at night. All of them hide by day and are common in the sylvatic area. Moreover, L. panamensis and L. gomezi successfully approach the house and seem to settle in the peridomestic area. L. shannoni and L. olmeca bicolor also approach and accidentally bite man. L. trinidadensis, L. atroclavata and L. cayennensis are the common non-antrhopophilic species in the area.

Occurrence and bioaccumulation study of PCDD and PCDF from mineral feed additives

Occurrence of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) was evaluated in sepiolite as a widely employed binder and anti-caking agent for animal feed. Also, naturally contaminated kaolinitic clay was used for comparative purposes. Since sepiolite shows remarkable adsorption properties, particular interest was paid to the extraction steps as they become critical for the final determination of these pollutants in such matrixes. Furthermore, classical Soxhlet extraction using different extracting strategies as well as acid treatment were carried out with simultaneous liquid-liquid extraction. Results obtained depended on the extraction procedure applied. Acid treatment or Soxhlet extraction using a mixture of toluene:ethanol as solvent allowed to reach the minimum requirements of recovery rates. However, Soxhlet extraction using a mixture cyclohexane:toluene as extracting solvent did not allow to comply with minimum specifications for recovery. Significant differences were obtained in TEQ units when acid treatment was applied in comparison to Soxhlet extraction. This fact can be explained because the use of drastic acid conditions allows removing strongly adsorbed analytes which can be uniquely extracted after a total destruction of the crystalline structure of sepiolite. On the contrary, Soxhlet extraction was not able to destroy the structure of sepiolite and as a consequence the PCDDs/Fs were strongly adsorbed in the internal structure of the mineral. From biological point of view the availability of these toxicants constitutes a critical aspect playing an important role in the final decision choosing particular analytical procedures. Then, acid conditions in the digestive tract should be taken into account. In this scenario, a bioaccumulation study was conducted to evaluate the transference of PCDDs/PCDFs from the sepiolite into the animal tissues when fed with feed containing sepiolite. To this end, chickens were used as a model to examine the bioavailability of PCDDs/PCDFs. Four groups of chickens were exposed through their diet to a control feed, feed with 3% w/w sepiolite as additive, feed contaminated with PCDDs/PCDFs at concentration around 2.8 pg WHO-TEQ/g and feed with 2% of a contaminated kaolinitic clay (460 pg TEQ/g mineral). Livers of the four studied groups were analyzed throughout the exposure period. Results of this trial showed that the performance of broilers was not affected by the presence of dioxins at levels tested, and chickens did not show any abnormal behaviour. Dioxins intentionally added to the diet were absorbed and accumulated in the liver in a significant manner, whereas the PCDDs/Fs from sepiolite were not available for chickens since livers from broilers fed 3% sepiolite presented similar WHO-TEQ values than those from broilers fed control diet.

The Measurement of social polarization in a multi-group context

Polarization indices presented up to now have only focused their attention on the distribution of income/wealth. However, in many circumstances income is not the only relevant dimension that might be the cause of social conflict, so it is very important to have a social polarization index able to cope with alternative dimensions. In this paper we present an axiomatic characterization of one of such indices: it has been obtained as an extension of the (income) polarization measure introduced in Duclos, Esteban and Ray (2004) to a wider domain. It turns out that the axiomatic structure introduced in that paper alone is not appropriate to obtain a fully satisfactory characterization of our measure, so additional axioms are proposed. As a byproduct, we present an alternative axiomatization of the aforementioned income polarization measure.

Ecology of sandflies (Diptera: Psychodidae) in a restricted focus of cutaneous leishmaniasis in Northern Venezuela: III. Seasonal fluctuation

A one year-long study (March 1979-March 1980) was carried out at San Esteban, an endemic focus of cutaneous leishmaniasis in Northern Venezuela, with the aim of observing the seasonal fluctuation of the local phlebotomine sandflies species. The influence of climatic factors (temperature, relative humidity and rainfall) on population dynamics was analyzed in three collecting sites - a house, a peridomestic area and a sylvatic region. Among anthropophilic species, L. panamensis behaved as a wetseason species, the mean minimum relative humidity being the critical factor influencing the total number of individuals. When the population density of this fly decreased, it was successfully replaced by L. ovallesi, a dry-season species. On the other hand, seasonal variations of L. gomezi were more strongly affected by the temperature.

Ecology of sandflies Diptera: Psychodidae) in a restricted focus of cutaneous leishmaniasis in Northern Venezuela: IV. Sandfly monthly fluctuation and leishmaniasis incidence relationship

An attempt has been made to correlate the monthly incidence of human leishmaniasis with the temporal distribution of sandfly species at San Esteban, Northern Venezuela. Upon statistical analysis, the seasonal fluctuation of L. ovallesi population correlated strongly with the human disease, while the dynamics of L. panamensis, generally believed to be the vector in the Central area of the country, showed only a very weak correlation. These findings support the hypothesis that L. panamensis might not be the main or unique species responsible for the transmission in this area and that L. ovallesi and additionally L. olmeca bicolor might be involved in the epidemiology of the disease.

Getting the most sulfate from soil: Regulation of sulfate uptake transporters in Arabidopsis.

Sulfur (S) is an essential macronutrient for all living organisms. Plants require large amounts of sulfate for growth and development, and this serves as a major entry point of sulfate into the food web. Plants acquire S in its ionic form from the soil; they have evolved tightly controlled mechanisms for the regulation of sulfate uptake in response to its external and internal availability. In the model plant Arabidopsis thaliana, the first key step in sulfate uptake is presumed to be carried out exclusively by only two high-affinity sulfate transporters: SULTR1;1 and SULTR1;2. A better understanding of the mode of regulation for these two transporters is crucial because they constitute the first determinative step in balancing sulfate in respect to its supply and demand. Here, we review the recent progress achieved in our comprehension of (i) mechanisms that regulate these two high-affinity sulfate transporters at the transcriptional and post-transcriptional levels, and (ii) their structure-function relationship. Such progress is important to enable biotechnological and agronomic strategies aimed at enhancing sulfate uptake and improving crop yield in S-deficient soils.

El largo viaje de Juan Preciado: propuesta de lectura de la novela Pedro Páramo desde la mitología nahua

Nuestro trabajo pretende abrir una nueva línea de análisis de la novela de Juan Rulfo Pedro Páramo que explore el arquetipo de la muerte que se esconde en el recorrido que realiza el protagonista de la novela, Juan Preciado, por el fantasmal pueblo de Comala, a través del mito nahua que narra el viaje del alma desencarnada al inframundo, al Mictlán