Revista CONTRIBUCIONES Científicas y Tecnológicas

EDITADA POR LA DIRECCIÓN DE INVESTIGACIÓN CIENTÍFICA Y TECNOLÓGICA VOL. 43  I  Nº 1  I  2018 ISSN 0716-0127 Versión Impresa ISSN 0719-8388 Versión en Líne

Human Foraging in a Virtual World

Methods for using the Torque® game engine to test the predictions of three optimal foraging models of human behavior are proposed. Traditional tests of Charnov’s marginal value theorem, the diet breadth model and the effect of energy Budget manipulation on risky choice are translated into a virtual world programmable through Torque®. Use of immersive environments allows participants to interact with experimental conditions that bear a greater functional resemblance to extra-laboratory environments, thereby increasing the ecological validity of the research

Guía Pedagógica: Producción de Cultivos Forrajeros

Guía pedagógic

Aspects of rain forest nutrient dynamics at Los Tuxtlas, Mexico.

Several aspects of nutrient cycling were studied in the Lowland Tropical Rain Forest at Los Tuxtlas. This is at (18° 34' - 18° 36’ N, 95° 04' - 95° 09' W) and represents the northernmost extension of the rain forest Formation in the New World. The relationships among the forest structure, small litterfall production (22 months), small litterfall element concentrations, and soil nutrients were investigated. The degree of nutrient resorption between fresh and dehisced leaves was evaluated for several tree species. The forest had a preponderance of mesophylls, a relatively low tree species diversity, basal area, and small litterfall production. An estimation of leaf litterfall contribution was provided for 119 woody species and the temporal variation of the leaf litterfall was described. Soil nutrient concentrations were high probably owing to the volcanic eruption of 1793. Nutrient-element concentrations were relatively high in the small litterfall and fresh leaves, and nutrient resorption was relatively low. The soil nutrient concentrations in pastures of 12, 32, and 52 years of age were compared with the forest and were relatively high in spite of their maintaining a high density of cattle. The soil under isolated trees in the pastures had higher nutrient concentrations than the open pastures. There was a higher diversity of seedling species under the isolated trees but a growth experiment in a tree nursery did not show differences among the soils from the undisturbed forest, open-pastures and under the isolated trees. It seems that soil nutrients are always high at Los Tuxtlas and override any effect of nutrient addition by the isolated trees

The influence of the Ratio Bias phenomenon on the elicitation of Standard Gamble utilities

This paper tests whether logically equivalent risk formats can lead to different health state utilities elicited by means of the standard gamble (SG) method. We compare SG utilities elicited when probabilities are framed in terms of frequencies with respect to 100 people in the population (i.e., X out of 100) with SG utilities elicited for frequencies with respect to 1,000 people in the population (i.e., Y out of 1,000). We found that utilities were significant higher when success and failure probabilities were framed as frequencies type “Y out of 1,000” rather than as frequencies type “X out of 100”. This framing effect, known as Ratio Bias, may have important consequences in resource allocation decisions.Framing effect, risk format, standard gamble, health state, dual-process theories.

SILAE 2011 en Fortaleza - Brasil

Gracias a una invitación de SILAE pude asistir entre el 19 y 22 de Septiembre de 2011 a su XX Congreso Italo-Latinoamericano de Etnomedicina que en esta oportunidad rendía un homenaje al Dr. Francisco José de Abreu Matos, creador de las Farmacias Verdes en Brasil. Este Congreso se realizó en la bella ciudad de Fortaleza, Estado de Ceará (Brasil). Fue un evento muy bien organizado y encabezado por el Dr. Ely Camargo de Sao Paulo e institucionalmente por el Consejo Nacional Farmacia de Brasil. En esta oportunidad fue elegido Presidente de SILAE por un año el Dr. Francesco de Simone (Italia)

Achieving Identity-based cryptography in a personal digital assistant

Continuous technological advances have allowed that mobile devices, such as Personal Digital Assistants (PDAs), can execute sophisticated applications that more often than not must be equipped with a layer of security that should include the confidentiality and the authentication services within its repertory. Nevertheless, when compared against front-end computing devices, most PDAs are still seen as constrained devices with limited processing and storage capabilities. In order to achieve Identity-Based Cryptography (IBC), which was an open problem proposed by Adi Shamir in 1984, Boneh and Franklin presented in Crypto 2001, a solution that uses bilinear pairings as its main building block. Since then, IBC has become an active area of investigation where many efficient IBC security protocols are proposed year after year. In this paper, we present a cryptographic application that allows the secure exchange of documents from a Personal Digital Assistant (PDA) that is wirelessly connected to other nodes. The architecture of our application is inspired by the traditional PGP (Pretty Good Privacy) email security protocol. Our application achieves identity-based authentication and confidentiality functionalities at the 80-bit security level through the usage of a cryptographic library that was coded in C++. Our library can perform basic primitives such as bilinear pairings defined over the binary field and the ternary field , as well as other required primitives known as map-to-point hash functions. We report the timings achieved by our application and we show that they compare well against other similar works published in the open literature