Optimal network topologies for information transmission in active networks

This work clarifies the relation between network circuit (topology) and behavior (information transmission and synchronization) in active networks, e.g. neural networks. As an application, we show how to determine a network topology that is optimal for information transmission. By optimal, we mean that the network is able to transmit a large amount of information, it possesses a large number of communication channels, and it is robust under large variations of the network coupling configuration. This theoretical approach is general and does not depend on the particular dynamic of the elements forming the network, since the network topology can be determined by finding a Laplacian matrix (the matrix that describes the connections and the coupling strengths among the elements) whose eigenvalues satisfy some special conditions. To illustrate our ideas and theoretical approaches, we use neural networks of electrically connected chaotic Hindmarsh-Rose neurons.Comment: 20 pages, 12 figure

Intergenerational transfers in rural households: A game theoretical approach

The household membership decision is viewed as a “research project” where the offspring invests in human and non human capital to influence the probability of finding an alternative to the parental household. The problem is formulated as a differential game between a selfish offspring and altruistic parents. The solution is consistent with facts” such as the “flexibility of inheritance systems” and the “generational fragmentation” of the family property when the economic opportunities expand outside the parental household.intergenerational transfers, rural households, game theory

Forest owners’ collective action against the risk of forest fire: a game theoretical approach

This paper is a follow up on a earlier one (Mendes, 1998) where I proposed a series of models for forest owners associations represented as organisation made up of two groups of strategically interacting players: the forest owners who are members of the association and the board of directors they have elected. The directors decide on the amount of services provided by the association which can be public goods (collective representation of the members, promotion of their common interests, diffusion of general information about forest programmes and best forest management practices, etc.) and private goods and services (silvicultural works preventive of forest fires, technical advice, etc.). The models were set up as games in strategic form with complete information and no payoff uncertainty. Here I pick up the second of, what is called in that previous paper, the "Portuguese" models and extend it in the following directions: - there is payoff risk for the forest owners due to exogenous hazards (forest fires or others); - forest owners can buy private services from the owners which contribute to reduce the losses resulting from those hazards. The main focus in this paper is to derive the comparative static results about the demand of these private services by the forest owners.forest owners’ associations, public and private goods joint supply, game theory

Values, norms, transactions and organizations

This paper may be considered an essay on metaeconomics, since it deals with the meaning of several concepts often left undefined, or very briefly defined in economic theories. These concepts are the following: value including the values of things and moral values, social norms or institutions, social power, goods and services, transactions and organizations (firms, and others). The paper starts by proposing a general concept of value, encompassing both the value of things and moral values. From this concept it proceeds to the definition of six different types of values of things and moral values and to the concept of value transformation process of things which includes all the operations dealt with in economic theory as well as many other human actions. The last part of the paper starts with the distinction between moral values and social norms (or institutions) and the roles of social power and human organization in connecting the domains of morality and social normativity. The paper proceeds by distinguishing different types of norms, including possession norms which are important for defining the concepts of goods and services and transaction processes.

Participation of non-industrial private forest owners in National Forest Programmes: a discrete choice model for Northern Portugal

In countries where private forest ownership is very important, knowledge of the behaviour of private forest owners is useful for the design and implementation of successful forest policies. This applies to Portugal where 86 % of the forest lands are private property. This paper presents a study carried out in a region of the Northern part of the country covered by a local forest owners’ association. Based on individual data about the members of this association concerning some of their characteristics (implementation of publicly subsidised afforestation projects, size of the forest holdings, number of forest holdings belonging to the same owner and distance between the permanent residence of the owner and his forest holdings), a multinomial logit model is estimated for the probabilities of participation on public incentive schemes to finance individual and grouped afforestation projects.non industrial private forest owners, afforestation projects, public incentives

The locomotion pattern of Baurusuchus salgadoensis Carvalho, Nobre & Campos, 2005 and the distribution of Baurusuchidae in Gondwanaland

Baurusuchus salgadoensis Carvalho, Nobre & Campos, 2005 is a ziphodont mesoeucrocodylian closely related to the Sebecosuchia. Cranial features indicate that this species had terrestrial predatory habits. The postcranial skeleton of B. salgadoensis show distinctive characteristics when compared to extant Crocodylomorpha. The dorsal vertebrae are close articulated with short and craniocaudally expanded neural spines, specially the posterior ones. The sacral vertebrae are robust and have the lateral processes highly fused to the ilium. The anterior caudal vertebrae are robust as the sacral ones but their neural spines are more stout, anteriorlly expanded and higher. The close articulation of the dorsal vertebrae may indicate a less flexible dorsal spine, ideal to limb-driven methods of locomotion. The high and expanded neural spines of the posterior dorsal and sacral vertebrae are associated to muscle attachment from the osteoderms and the pelvic musculature, all used in the limb-driven locomotion. The appendicular bones of B. salgadoensis are long and stout. They show a straight aspect of their diaphysis and very well- developed epiphysis. The femur is long when compared to extant crocodilians, showing a straight aspect in lateral view and a slight sigmoid aspect in frontal view. There is a small axial torsion at its proximal end. The fourth trochanter is pronouced and posteriorlly oriented. The proximal end possess a mesial projection that articulates itself to the illium, similar to those of Protosuchia and thecodont archosaurs as the Rauisuchia. The illium of B. salgadoensis present a lateral and posteriorlly expanded postaccetabular crest, similar to those observed in Rauisuchia and Protosuchia, referred as overhanging ilium. This pattern of articulation is observed in the rauisuchian thecodonts and interpreted as a characteristic trait of those able erect-posture and limb-driven predators of Triassic environments. B. salgadoensis exoskeleton has only two dorsal osteoderm rows that run from the neck to the tip of the tail. Most of the osteoderms are wider than longer, with a round lateral portion that does not articulate to any flank osteoderm. The only morphological difference appears at the caudalmost portion of the tail, where the osteoderms are craniocaudally elongated. The medial portion has little variation along the scutes rows and may bear medial lamellar dorsoventral structures of articulation to the adjacent bony plate. The anterior articular facet is discreet and the osteoderms are not as imbricated as occur in other crocodyliforms and even may not be imbricated at all. The pelvic region osteoderms have the tallest keel of the row that runs from the anterior articular facet to posteriosmost portion of the osteoderm. B. salgadoensis has a light exoskeleton and then is less encumbranced by it. Therefore, becaming more agile. The imbrication of dorsal armor assists the limb-driven locomotion of many crocodyliform by reducing the flexibility of the dorsal spine during the high-walk (erect stance). Therefore the long and stout limb bones, overhanging crest of the illium and the light weighted armor, also allowed to B. salgadoensis to have the limb-driven locomotion without this pattern of osteoderms. These anatomical data may indicate how the Baurusuchidae had a wide distribution in Gondwanaland as they were able to move across large distances

A Game Theoretical Model of Land Contract Choice

In most of the land tenancy literature the type of contract is exogenous. Also even though these contracts vary a lot among farms, between regions and over time, the theoretical literature has not always acknowledged this idiosyncrasy. Building on the strategic bargaining theory initiated by Rubinstein, this model not only makes the type of contract endogenous, but also provides the surplus sharing rules and the conditions giving rise to each type of contract, showing how the type and terms of the contract are tailored to fit the characteristics of the parties and their economic environment. Pairwise bargaining is embedded into a market context by putting “competitive pressure” on the players through the opportunity they have to break up bargaining and look for alternative partners. Because of this threat of opting out, the outcome of the bargaining process depends not only on the characteristics of the players, but also on events outside their match and the information they have about them. The model departs from price-taking assumptions. Type and terms of the contract result from negotiation and are shaped by the “relative bargaining powers” of the players whose relevant components are identified in a precise way in the model.land tenancy, sharecropping, land contract choice, game theory