Consistency and the core of multi-sided assignment markets

[cat] En aquest treball es demostra que en el domini dels jocs d’assignació equilibrats multisectorials (Quint, 1991), el core és l’única solució no buida que satisfà derived consistency i projection consistency. També es caracteritza el core en tota la classe dels jocs d’assignació multisectorials amb els axiomes de singleness best, individual antimonotonicity i derived consistency. Com a casos particulars, s’obtenen dues noves axiomàtiques del core per als jocs d’assignació bilaterals (Shapley and Shubik, 1972).

A geometric chracterization of the nucleolus of the assignment game

Maschler et al. (1979) caracteritzen geomètricament la intersecció del kernel i del core en els jocs cooperatius, demostrant que les distribucions que pertanyen a ambdós conjunts es troben en el punt mig d’un cert rang de negociació entre parelles de jugadors. En el cas dels jocs d’assignació, aquesta caracterització vol dir que el kernel només conté aquells elements del core on el màxim que un jugador pot transferir a una parella òptima és igual al màxim que aquesta parella li pot transferir, sense sortir-se’n del core. En aquest treball demostrem que el nucleolus d’un joc d’assignació queda caracteritzat si requerim que aquesta propietat de bisecció es compleixi no només per parelles, sinó també per coalicions entre sectors aparellades òptimament.

A geometric chracterization of the nucleolus of the assignment game

Maschler et al. (1979) caracteritzen geomètricament la intersecció del kernel i del core en els jocs cooperatius, demostrant que les distribucions que pertanyen a ambdós conjunts es troben en el punt mig d’un cert rang de negociació entre parelles de jugadors. En el cas dels jocs d’assignació, aquesta caracterització vol dir que el kernel només conté aquells elements del core on el màxim que un jugador pot transferir a una parella òptima és igual al màxim que aquesta parella li pot transferir, sense sortir-se’n del core. En aquest treball demostrem que el nucleolus d’un joc d’assignació queda caracteritzat si requerim que aquesta propietat de bisecció es compleixi no només per parelles, sinó també per coalicions entre sectors aparellades òptimament.

Assignment markets with the same core

[spa] En el contexto de los juegos de asignación bilaterales, estudiamos el conjunto de matrices asociadas a mercados de asignación con el mismo nucleo. Se proporcionan condiciones sobre las entradas de la matriz que aseguran que los juegos de asignación asociados tienen el mismo núcleo. Se prueba que este conjunto de matrices que dan lugar al mismo núcleo forman un semirretículo con un número finito de elementos minimales y un único máximo. Se da una caracterización de estos elementos minimales. También se proporciona una condición suficiente para obtener un retículo.

Multi-sided Böhm-Bawerk assignment markets: the core

[cat] En aquest treball introduïm la classe de "multi-sided Böhm-Bawerk assignment games", que generalitza la coneguda classe de jocs d’assignació de Böhm-Bawerk bilaterals a situacions amb un nombre arbitrari de sectors. Trobem els extrems del core de qualsevol multi-sided Böhm-Bawerk assignment game a partir d’un joc convex definit en el conjunt de sectors enlloc del conjunt de venedors i compradors. Addicionalment estudiem quan el core d’aquests jocs d’assignació és estable en el sentit de von Neumann-Morgenstern.

Consistency and the core of multi-sided assignment markets

[cat] En aquest treball es demostra que en el domini dels jocs d’assignació equilibrats multisectorials (Quint, 1991), el core és l’única solució no buida que satisfà derived consistency i projection consistency. També es caracteritza el core en tota la classe dels jocs d’assignació multisectorials amb els axiomes de singleness best, individual antimonotonicity i derived consistency. Com a casos particulars, s’obtenen dues noves axiomàtiques del core per als jocs d’assignació bilaterals (Shapley and Shubik, 1972).

Studying the non-thermal lobes of IRAS 16547-4247 through a multi-wavelength approach

In recent years, massive protostars have turned out to be a possible population of high-energy emitters. Among the best candidates is IRAS 16547-4247, a protostar that presents a powerful outflow with clear signatures of interaction with its environment. This source has been revealed to be a potential high-energy source because it displays non-thermal radio emission of synchrotron origin, which is evidence of relativistic particles. To improve our understanding of IRAS 16547-4247 as a high-energy source, we analyzed XMM-Newton archival data and found that IRAS 16547-4247 is a hard X-ray source. We discuss these results in the context of a refined one-zone model and previous radio observations. From our study we find that it may be difficult to explain the X-ray emission as non-thermal radiation coming from the interaction region, but it might be produced by thermal Bremsstrahlung (plus photo-electric absorption) by a fast shock at the jet end. In the high-energy range, the source might be detectable by the present generation of Cherenkov telescopes, and may eventually be detected by Fermi in the GeV range.

Deep GMRT radio observations and a multi-wavelength study of the region around HESS J1858+020

Context. There are a number of very high energy sources in the Galaxy that remain unidentified. Multi-wavelength and variability studies, and catalogue searches, are powerful tools to identify the physical counterpart, given the uncertainty in the source location and extension. Aims. This work carries out a thorough multi-wavelength study of the unidentified, very high energy source HESS J1858+020 and its environs. Methods. We have performed Giant Metrewave Radio Telescope observations at 610 MHz and 1.4 GHz to obtain a deep, low-frequency radio image of the region surrounding HESS J1858+020. We analysed archival radio, infrared, and X-ray data as well. This observational information, combined with molecular data, catalogue sources, and a nearby Fermi gamma-ray detection of unidentified origin, are combined to explore possible counterparts to the very high energy source. Results. We provide with a deep radio image of a supernova remnant that might be related to the GeV and TeV emission in the region. We confirm the presence of an H ii region next to the supernova remnant and coincident with molecular emission. A potential region of star formation is also identified. We identify several radio and X-ray sources in the surroundings. Some of these sources are known planetary nebulae, whereas others may be non-thermal extended emitters and embedded young stellar objects. Three old, background Galactic pulsars also neighbour HESS J1858+020 along the line of sight. Conclusions. The region surrounding HESS J1858+020 is rich in molecular structures and non-thermal objects that may potentially be linked to this unidentified very high energy source. In particular, a supernova remnant interacting with nearby molecular clouds may be a good candidate, but a star forming region, or a non-thermal radio source of yet unclear nature, may also be behind the gamma-ray source. The neighbouring pulsars, despite being old and distant, cannot be discarded as candidates. Further observational studies are needed, however, to narrow the search for a counterpart to the HESS source.

One-seller assignment markets with multi-unit demands

We consider one-seller assignment markets with multi-unit demands and prove that the associated game is buyers-submodular. Therefore the core is non-empty and it has a lattice structure which contains the allocation where every buyer receives his marginal contribution. We prove that in this kind of market, every pairwise-stable outcome is associated to a competitive equilibrium and viceversa. We study conditions under which the buyers-optimal and the seller-optimal core allocations are competitive equilibrium payoff vectors. Moreover, we characterize the markets for which the core coincidences with the set of competitive equilibria payoff vectors. When agents behave strategically, we introduce a procedure that implements the buyers-optimal core allocation as the unique subgame perfect Nash equilibrium outcome.

Isolation, structural assignment and total synthesis of Barmumycin

Barmumycin was isolated from an extract of the marine actinomycete Streptomyces sp. BOSC-022A and found to be cytotoxic against various human tumor cell lines. Based on preliminary one- and two-dimensional 1H- and 13C-NMR spectra, the natural compound was initially assigned the structure of macrolactone-type compound 1, which was later prepared by two different routes. However, major spectroscopic differences between isolated barmumycin and 1 led to revision of the proposed structure as E-16. Based on synthesis of this new compound, and subsequent spectroscopic comparison of it to an authentic sample of barmumycin, the structure of the natural compound was indeed confirmed as that of E-16.

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

Three Wavelength Optical Probe for Surface Roughness Measurements of Paper Samples

In the present diploma work optical inspection methods were used to investigate surface roughness of paper samples. A special measurement setup, which includes three laser light sources of three different wavelengths, photodetector and goniometer, was used to measure the reflected laser light properties. The intensity of the light reflected in specular direction was measured versus the laser incidence angle for reference metal sample. The value of roughness was estimated and compared to initially known value of metal sample roughness. Thus, the measurement equipment and method were validated. Then the reflected intensity was measured versus reflection angle at constant incidence angle for the same metal sample and paper samples under investigation. The final values of the surface roughness were obtained from the analysis of the reflected intensity dependence. The results are in good correlation with other research groups.