Geographic assignment of seabirds to their origin: combining morphology, genetics and biogeochemical analyses

Longline fisheries, oil spills, and offshore wind farms are some of the major threats increasing seabird mortality at sea, but the impact of these threats on specific populations has been difficult to determine so far. We tested the use of molecular markers, morphometric measures, and stable isotope (δ15N and δ13C) and trace element concentrations in the first primary feather (grown at the end of the breeding period) to assign the geographic origin of Calonectris shearwaters. Overall, we sampled birds from three taxa: 13 Mediterranean Cory's Shearwater (Calonectris diomedea diomedea) breeding sites, 10 Atlantic Cory's Shearwater (Calonectris diomedea borealis) breeding sites, and one Cape Verde Shearwater (C. edwardsii) breeding site. Assignment rates were investigated at three spatial scales: breeding colony, breeding archipelago, and taxa levels. Genetic analyses based on the mitochondrial control region (198 birds from 21 breeding colonies) correctly assigned 100% of birds to the three main taxa but failed in detecting geographic structuring at lower scales. Discriminant analyses based on trace elements composition achieved the best rate of correct assignment to colony (77.5%). Body measurements or stable isotopes mainly succeeded in assigning individuals among taxa (87.9% and 89.9%, respectively) but failed at the colony level (27.1% and 38.0%, respectively). Combining all three approaches (morphometrics, isotopes, and trace elements on 186 birds from 15 breeding colonies) substantially improved correct classifications (86.0%, 90.7%, and 100% among colonies, archipelagos, and taxa, respectively). Validations using two independent data sets and jackknife cross-validation confirmed the robustness of the combined approach in the colony assignment (62.5%, 58.8%, and 69.8% for each validation test, respectively). A preliminary application of the discriminant model based on stable isotope δ15N and δ13C values and trace elements (219 birds from 17 breeding sites) showed that 41 Cory's Shearwaters caught by western Mediterranean long-liners came mainly from breeding colonies in Menorca (48.8%), Ibiza (14.6%), and Crete (31.7%). Our findings show that combining analyses of trace elements and stable isotopes on feathers can achieve high rates of correct geographic assignment of birds in the marine environment, opening new prospects for the study of seabird mortality at sea.

Generalized three-sided assignment markets: consistency and the core

A class of three-sided markets (and games) is considered, where value is generated by pairs or triplets of agents belonging to different sectors, as well as by individuals. For these markets we analyze the situation that arises when some agents leave the market with some payoff To this end, we introduce the derived market (and game) and relate it to the Davis and Maschler (1965) reduced game. Consistency with respect to the derived market, together with singleness best and individual anti-monotonicity axiomatically characterize the core for these generalized three-sided assignment markets. These markets may have an empty core, but we define a balanced subclass, where the worth of each triplet is defined as the addition of the worths of the pairs it contains. Keywords: Multi-sided assignment market, Consistency, Core, Nucleolus. JEL Classification: C71, C78

On the structure of cooperative and competitive solutions for a generalized assignment game

We study cooperative and competitive solutions for a many- to-many generalization of Shapley and Shubik (1972)'s assignment game. We consider the Core, three other notions of group stability and two al- ternative definitions of competitive equilibrium. We show that (i) each group stable set is closely related with the Core of certain games defined using a proper notion of blocking and (ii) each group stable set contains the set of payoff vectors associated to the two definitions of competitive equilibrium. We also show that all six solutions maintain a strictly nested structure. Moreover, each solution can be identified with a set of ma- trices of (discriminated) prices which indicate how gains from trade are distributed among buyers and sellers. In all cases such matrices arise as solutions of a system of linear inequalities. Hence, all six solutions have the same properties from a structural and computational point of view.

Double implementation in a market for indivisible goods with a price constraint

I consider the problem of assigning agents to objects where each agent must pay the price of the object he gets and prices must sum to a given number. The objective is to select an assignment-price pair that is envy-free with respect to the true preferences. I prove that the proposed mechanism will implement both in Nash and strong Nash the set of envy-free allocations. The distinguishing feature of the mechanism is that it treats the announced preferences as the true ones and selects an envy-free allocation with respect to the announced preferences.

Fair and efficient student placement with couples

We study situations of allocating positions or jobs to students or workers based on priorities. An example is the assignment of medical students to hospital residencies on the basis of one or several entrance exams. For markets without couples, e.g., for ``undergraduate student placement,'' acyclicity is a necessary and sufficient condition for the existence of a fair and efficient placement mechanism (Ergin, 2002). We show that in the presence of couples, which introduces complementarities into the students' preferences, acyclicity is still necessary, but not sufficient (Theorem 4.1). A second necessary condition (Theorem 4.2) is ``priority-togetherness'' of couples. A priority structure that satisfies both necessary conditions is called pt-acyclic. For student placement problems where all quotas are equal to one we characterize pt-acyclicity (Lemma 5.1) and show that it is a sufficient condition for the existence of a fair and efficient placement mechanism (Theorem 5.1). If in addition to pt-acyclicity we require ``reallocation-'' and ``vacancy-fairness'' for couples, the so-called dictator-bidictator placement mechanism is the unique fair and efficient placement mechanism (Theorem 5.2). Finally, for general student placement problems, we show that pt-acyclicity may not be sufficient for the existence of a fair and efficient placement mechanism (Examples 5.4, 5.5, and 5.6). We identify a sufficient condition such that the so-called sequential placement mechanism produces a fair and efficient allocation (Theorem 5.3).

Efficient priority rules

We study the assignment of indivisible objects with quotas (houses, jobs, or offices) to a set of agents (students, job applicants, or professors). Each agent receives at most one object and monetary compensations are not possible. We characterize efficient priority rules by efficiency, strategy-proofness, and renegotiation-proofness. Such a rule respects an acyclical priority structure and the allocations can be determined using the deferred acceptance algorithm.

Constrained school choice

Recently, several school districts in the US have adopted or consider adopting the Student-Optimal Stable Mechanism or the Top Trading Cycles Mechanism to assign children to public schools. There is clear evidence that for school districts that employ (variants of) the so-called Boston Mechanism the transition would lead to efficiency gains. The first two mechanisms are strategy-proof, but in practice student assignment procedures impede students to submit a preference list that contains all their acceptable schools. Therefore, any desirable property of the mechanisms is likely toget distorted. We study the non trivial preference revelation game where students can only declare up to a fixed number (quota) of schools to be acceptable. We focus on the stability of the Nash equilibrium outcomes. Our main results identify rather stringent necessary and sufficient conditions on the priorities to guaranteestability. This stands in sharp contrast with the Boston Mechanism which yields stable Nash equilibrium outcomes, independently of the quota. Hence, the transition to any of the two mechanisms is likely to come with a higher risk that students seek legal actionas lower priority students may occupy more preferred schools.

Personal relations and their effect on behavior in an organizational setting: an experimental study

We study how personal relations affect performance in organizations. In the experimental game we use a manager has to assign different degrees of decision power to two employees. These two employees then have to make distributive decisions which affect themselves and the manager. Our focus is on the effects on managers' assignment of decision power and on employees' distributive decisions of one of the employees and the manager knowing each other personally. Our evidence shows that managers tend to favor employees that they personally know and that these employees tend, more than other employees, to favor the manager in their distributive decisions. However, this behavior does not affect the performance of the employees that do not know the manager. All these effects are independent of whether the employees that know the manager are more or less productive than those who do not know the manager. The results shed light on discrimination and nepotism and its consequences for the performance of family firms and other organizations.

Gestor intel·ligent d'assignació de recursos

Aquest projecte és una eina per a la gestió avançada del Comitè Tècnic d’Àrbitres de Futbol Sala de Catalunya. Creant una base de dades forta i robusta com la que ens proporciona la tecnologia ORACLE, i agafant APEX com a gestor de continguts de la base de dades, hem creat una aplicació per realitzar l'assignació d'arbitratges i altres recursos d'una manera intel·ligent i equitativa.

Enquestes: aplicació web per a la creació d'enquestes

Les enquestes són un mètode excel·lent per a extreure informació relativa a conjunts de població específics, amb la finalitat de conèixer l’opinió d’aquests sobre l’objectiu de la enquesta. En aquest treball es proposa una implementació d’una aplicació que té com objectiu reduir l’esforç associat a la creació d’enquestes, recepció de respostes i visualització de resultats. Totes les tecnologies utilitzades són gratuïtes, i la implementació es porta a terme amb els estàndards de J2EE, prioritzant la extensibilitat i la portabilitat per sobre altres característiques.

Gestió d'espais i control d'accés en edificis públics

El present projecte desenvolupa una aplicació de gestió d’espais i control d’accés per a la l’Edifici d’Estudiants-ETC de la Universitat Autònoma de Barcelona. Aquest edifici ofereix serveis a la comunitat universitària i compta amb un conjunt d’espais i equipaments ben divers: despatxos, sales de reunió, sales d’assaig, sala d’ordinadors, cinema i teatre. Els usuaris d’aquestes instal·lacions són els propis treballadors de l’edifici, alumnes dels cursos i tallers, estudiants beneficiaris d’algun servei i col·lectius d’estudiants. La gestió i l’assignació d’aquests espais, així com el control d’accés són realitzats manualment per part del personal de l’ETC a la recepció de l’edifici (anomenat Punt de Serveis). L’aplicació desenvolupada implementa els processos existents, tals com la gestió i reserva d’espais, l’inventari de claus o el control d’accés a les sales. Tanmateix introdueix nous processos i funcionalitats, com la gestió, reserva i cessió de material propietat de l’edifici.

Els cócs : Una senya d'identitat a la Terra Alta

He organitzat aquest escrit de la manera següent: començo amb una visió general de l'entorn social i econòmic de la comarca, faig esment de breus aspectes lingüístics dels mots, continuo amb un breu repàs de la literatura culinària, principalment a Catalunya, i amb una breu visió històrica, continuo amb el món del pa i de la pastisseria i acabo amb la visió més lúdica dels cócs: el moment de consumir-los. Finalment entro en l'exposició de les receptes més genuïnes dels cócs terraltins, mirant que quedi tot ben clar, gràcies a la informació desinteressada de les persones a qui he consultat, i les comparo amb altres de semblants que trobem en antics manuscrits medievals. Per acabar, mostro quines conclusions podem extreure sobre els cócs i els dolços de la Terra Alta, vinculades bàsicament amb el seu origen i la seva continuïtat fins als nostres dies.

Construcció d'un SIG de base municipal amb assignació automàtica del nom de carrer a les illes d'habitatges d'una determinada població

Aquest document explica, en els seus diferents capítols, la construcció d'un SIG de base municipal amb assignació automàtica del nom de carrer a les illes d'habitatges d'una determinada població, utilitzant les eines GeoMedia Professional i Visual Basic.

Innovación, financiación y mercados financieros : análisis de las relaciones entre inversión en I+D, estructura de capital y señalización contable

Aquest treball té com a objectiu determinar l'existència de restriccions en el finançament de projectes empresarials de recerca i desenvolupament (R+D) i analitzar-ne les causes. Els resultats de la investigació mostren els fets següents: en primer lloc, hi ha restriccions financeres per a la realització d'inversions en R+D i es manifesten en la necessitat de les empreses de recórrer a recursos interns i a fons aliens a curt termini; en segon lloc, les restriccions esmentades fonamentalment sorgeixen a causa de dos factors, el desequilibri entre les característiques econòmiques de les inversions d'R+D i el comportament dels agents finançadors en els mercats de capitals, i l'existència d'asimetries d'informació entre agents gestors i finançadors; finalment, en tercer lloc, la formulació per part de les empreses de més informació comptable sobre l'R+D desenvolupada comporta la millora de la valoració de l'empresa en els mercats financers i, per tant, l'assignació de fons als processos d'innovació.

The short arm of the law: judicial institutions and local governance in Brazil

This paper estimates the effect of judicial institutions on governance at the local level in Brazil. Our estimation strategy exploits a unique institutional feature of state judiciary branches which assigns prosecutors and judges to the most populous among contiguous counties forming a judiciary district. As a result of this assignment mechanism there are counties with nearly identical populations, some with and some without local judicial presence, which we exploit to impute counterfactual outcomes. Conditional on observable county characteristics, offenses per civil servant are about 35% lower in counties that have a local seat of the state judiciary. The lower incidence of infractions stems mostly from fewer violations of financial management regulations by local administrators, fewer instances of problems in project execution and project managment, fewer cases of non-existent or ineffective civil society oversight and fewer cases of improper handling of remittances to local residents.