Payoff-dependent balancedness and cores (revised version)

We prove the non-emptiness of the core of an NTU game satisfying a condition of payoff-dependent balancedness, based on transfer rate mappings. We also define a new equilibrium condition on transfer rates and we prove the existence of core payoff vectors satisfying this condition. The additional requirement of transfer rate equilibrium refines the core concept and allows the selection of specific core payoff vectors. Lastly, the class of parametrized cooperative games is introduced. This new setting and its associated equilibrium-core solution extend the usual cooperative game framework and core solution to situations depending on an exogenous environment. A non-emptiness result for the equilibrium-core is also provided in the context of a parametrized cooperative game. Our proofs borrow mathematical tools and geometric constructions from general equilibrium theory with non convexities. Applications to extant results taken from game theory and economic theory are given.

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.

In rats, oral oleoyl-DHEA is rapidly hydrolysed and converted to DHEA-sulphate

Background: Dehydroepiandrosterone (DHEA) released by adrenal glands may be converted to androgens and estrogens mainly in the gonadal, adipose, mammary, hepatic and nervous tissue. DHEA is also a key neurosteroid and has antiglucocorticoid activity. DHEA has been used for the treatment of a number of diseases, including obesity; its pharmacological effects depend on large oral doses, which effect rapidly wanes in part because of its short half-life in plasma. Since steroid hormone esters circulate for longer periods, we have studied here whether the administration of DHEA oleoyl ester may extend its pharmacologic availability by keeping high circulating levels. Results: Tritium-labelled oleoyl-DHEA was given to Wistar male and female rats by gastric tube. The kinetics of appearance of the label in plasma was unrelated to sex; the pattern being largely coincident with the levels of DHEA-sulfate only in females, and after 2 h undistinguishable from the results obtained using labelled DHEA gavages; in the short term, practically no lipophilic DHEA label was found in plasma. After 24 h only a small fraction of the label remained in the rat organs, with a different sex-related distribution pattern coincident for oleoyl- and free- DHEA gavages. The rapid conversion of oleoyl-DHEA into circulating DHEA-sulfate was investigated using stomach, liver and intestine homogenates; which hydrolysed oleoyl-DHEA optimally near pH 8. Duodenum and ileum contained the highest esterase activities. Pure hog pancreas cholesterol-esterase broke down oleoyl-DHEA at rates similar to those of oleoyl-cholesterol. The intestinal and liver esterases were differently activated by taurocholate and showed different pH-activity patterns than cholesterol esterase, suggesting that oleoyl-DHEA can be hydrolysed by a number of esterases in the lumen (e.g. cholesterol-esterase), in the intestinal wall and the liver. Conclusion: The esterase activities found may condition the pharmacological availability (and depot effect) of orally administered steroid hormone fatty acid esters such as oleoyl-DHEA. The oral administration of oleoyl-DHEA in order to extend DHEA plasma availability has not been proved effective, since the ester is rapidly hydrolysed, probably in the intestine itself, and mainly converted to DHEA-sulfate at least in females.

"Suddenly I get into the zone": Examining discontinuities and nonlinear changes in flow experiences at work

Work-related flow is defined as a sudden and enjoyable merging of action and awareness that represents a peak experience in the daily lives of workers. Employees" perceptions of challenge and skill and their subjective experiences in terms of enjoyment, interest and absorption were measured using the experience sampling method, yielding a total of 6981 observations from a sample of 60 employees. Linear and nonlinear approaches were applied in order to model both continuous and sudden changes. According to the R2, AICc and BIC indexes, the nonlinear dynamical systems model (i.e. cusp catastrophe model) fit the data better than the linear and logistic regression models. Likewise, the cusp catastrophe model appears to be especially powerful for modelling those cases of high levels of flow. Overall, flow represents a nonequilibrium condition that combines continuous and abrupt changes across time. Research and intervention efforts concerned with this process should focus on the variable of challenge, which, according to our study, appears to play a key role in the abrupt changes observed in work-related flow.

Ligand binding to heparan sulfate proteoglycans induces their aggregation and distribution along actin cytoskeleton

Cell surface heparan sulfate proteoglycans (HSPGs) participate in molecular events that regulate cell adhesion, migration, and proliferation. The present study demonstrates that soluble heparin-binding proteins or cross-linking antibodies induce the aggregation of cell surface HSPGs and their distribution along underlying actin filaments. Immunofluorescence and confocal microscopy and immunogold and electron microscopy indicate that, in the absence of ligands, HSPGs are irregularly distributed on the fibroblast cell surface, without any apparent codistribution with the actin cytoskeleton. In the presence of ligand (lipoprotein lipase) or antibodies against heparan sulfate, HSPGs aggregate and colocalize with the actin cytoskeleton. Triton X-100 extraction and immunoelectron microscopy have demonstrated that in this condition HSPGs were clustered and associated with the actin filaments. Crosslinking experiments that use biotinylated lipoprotein lipase have revealed three major proteoglycans as binding sites at the fibroblast cell surface. These cross-linked proteoglycans appeared in the Triton X-100 insoluble fraction. Platinum/carbon replicas of the fibroblast surface incubated either with lipoprotein lipase or antiheparan sulfate showed large aggregates of HSPGs regularly distributed along cytoplasmic fibers. Quantification of the spacing between HSPGs by confocal microscopy confirmed that the nonrandom distribution of HSPG aggregates along the actin cytoskeleton was induced by ligand binding. When cells were incubated either with lipoprotein lipase or antibodies against heparan sulfate, the distance between immunofluorescence spots was uniform. In contrast, the spacing between HSPGs on fixed cells not incubated with ligand was more variable. This highly organized spatial relationship between actin and proteoglycans suggests that cortical actin filaments could organize the molecular machinery involved in signal transduction and molecular movements on the cell surface that are triggered by heparin-binding proteins.

Calidad de vida relacionada con la salud y consumo de tabaco

La calidad de vida relacionada con la salud se ha descrito como un concepto multidimensional que incluye la identificación de síntomas, el estado funcional, la percepción de bienestar psicológico y la percepción general de salud. En el caso de la adicción al consumo de tabaco, la preocupación por la salud actual o futura es uno de los motivos más informados para dejar de fumar. En el presente estudio se analiza la relación entre la percepción de la calidad de vida relacionada con la salud y la etapa de cambio en el abandono del consumo de tabaco propuesta desde el modelo transteórico a fin de mejorar las estrategias de intervención comunitaria y clínica para la cesación tabáquica. Se ha administrado el cuestionario SF-36 a una muestra formada por 201 fumadores y exfumadores. Los datos obtenidos indican peor salud física percibida en las etapas de cambio más próximas al abandono de tabaco y una peor salud mental percibida en las etapas con tabaquismo activo. Se comparan los resultados con los observados en otras poblaciones y se discuten las implicaciones a nivel de tratamiento y prevención del tabaquismo

A Negotiation Style Recommender Based on Computational Ecology in Open Negotiation Environments

The system described herein represents the first example of a recommender system in digital ecosystems where agents negotiate services on behalf of small companies. The small companies compete not only with price or quality, but with a wider service-by-service composition by subcontracting with other companies. The final result of these offerings depends on negotiations at the scale of millions of small companies. This scale requires new platforms for supporting digital business ecosystems, as well as related services like open-id, trust management, monitors and recommenders. This is done in the Open Negotiation Environment (ONE), which is an open-source platform that allows agents, on behalf of small companies, to negotiate and use the ecosystem services, and enables the development of new agent technologies. The methods and tools of cyber engineering are necessary to build up Open Negotiation Environments that are stable, a basic condition for predictable business and reliable business environments. Aiming to build stable digital business ecosystems by means of improved collective intelligence, we introduce a model of negotiation style dynamics from the point of view of computational ecology. This model inspires an ecosystem monitor as well as a novel negotiation style recommender. The ecosystem monitor provides hints to the negotiation style recommender to achieve greater stability of an open negotiation environment in a digital business ecosystem. The greater stability provides the small companies with higher predictability, and therefore better business results. The negotiation style recommender is implemented with a simulated annealing algorithm at a constant temperature, and its impact is shown by applying it to a real case of an open negotiation environment populated by Italian companies

Bosque y turismo

This paper presents a number of considerations on the recreational/tourism function offorests and some regulations that should be present in the planning of the public use of forestspace. We are going to examine studies on frequency of use, the features that condition theuse of forests and the criteria that should be present on planning of recreational use of forests

Female stereotypes in household appliances advertising and their social role in Spain: the perpetuation of a no- longer-existing female condition

The following dissertation proposes a qualitative approach on the matter ofadvertising, society and construction of identity, based on the effect of householdappliances commercials in constructing female identity of Spanish women today.Conclusions will be drawn based on a juxtaposition of social background andadvertising content and on how Spanish women of today perceive the evolution offemale imagery depicted in advertisements. The aim is to demonstrate how muchcommercials mirrors society and how far it reinforces paradigms no longer existing

World-line condition and the noninteraction theorem

A 6N-dimensional alternative formulation is proposed for constrained Hamiltonian systems. In this context the noninteraction theorem is derived from the world-line conditions. A model of two interacting particles is exhibited where physical coordinates are canonical.

El juego y su estructura interna en relación con el trabajo de la condición física en primaria = Games and their internal structure in relation to the work of physical condition in Primary Education

One of the methodological resources that teachers use in a generalised way in Physical Education classes is the game. Inthis article we define the concept of game and analyse the characteristics of their internal structure. On the other hand welook at the concepts of physical condition and conditional skills and describe the objectives of its work in Primary Education.Finally, we relate these concepts and propose two practical examples of modifying the internal structure of the game so asto produce variations in the implied conditional skills