The dynamics of a nudibranch-hydroid predator-prey association: Cuthona nana and Hydractinia echinata

The purpose of this study was to document the biological interactions in a predator-prey relationship involving a nudibranch and hydroid, respectively. The predator is a hermaphroditic opisthobranch mollusc with direct development, Cuthona nana. Cuthona nana feeds specifically on the colonial hydroid Hydractinia echinata. Population patterns of predator and prey were documented by collecting hermit crabs with hydroid-covered shells. Results indicate a subannual life cycle for C. nana with juveniles and egg masses present throughout the year. Hydractinia echinata colonies reproduce in the spring and are more abundant in late summer and early fall. Field and laboratory observations indicate that adult nudibranchs leave hydroid colonies to lay egg masses. Adults moved on and off of colonies while juveniles did not leave the colonies on which they were originally placed. The crab seems to play a part in bringing food to newly hatched juvenile or adult nudibranchs on the bottom. The maintenance of this species-specific association can be explained by partial predation of the colonies. Spines prevent complete removal of tissue. Hydroid colonies are capable of regeneration and can withstand cropping by nudibranchs. Hermit crab movement may be positive for both the nudibranch and hydroid. The hydroid obtains food from the sandy bottom as the crab moves about and is also moved away from predators. Nudibranchs can be dispersed by crab movement and also obtain food if a crab has a hydroid colony on its shell. (Abstract shortened with permission of author.)

Thermodynamic Framework of Multiscale Homogenization Schemes for Dissipative Materials

The prediction of failure processes in composite, heterogeneous materials require multiscale analysis to account for the complex mechanisms and features taking place. Between the different multiscale schemes the more commonly used are those based on homogenization procedures, due to their versatility. In this work a thermodynamically consistent homogenisation based multiscale approach is formulated for modelling thermo-plastic materials. The proposal is valid for arbitrary multiscale procedures, including local or nonlocal methods, and continuum or discontinuum methods in either scale. The necessary and sufficient conditions for fulfilling the thermodynamic consistency are defined. It is demonstrated that the Hill-Mandel variational criterion for homogenization scheme is a necessary, but not a sufficient condition when dissipative material responses are involved at any scale. On this point, the additional condition that needs to be fulfilled is established. The general case of temperature-dependent, higher order elastoplasticity is considered as theoretical framework to account for the material dissipation at micro and macro scales of observation. Additionally, it is shown that the thermodynamic consistency enforces the homogenization of the nonlocal terms of the micro scale’s free energy density; however, this does not necessarily lead to nonlocal effects on the macro scale. Finally, the particular cases of local isothermal elastoplasticity and continuum damage are considered for the purpose of the proposed approach for multiscale homogenizations.Publicado en: Mecánica Computacional vol. XXXV, no. 23Facultad de Ingenierí

Thermodynamic Framework of Multiscale Homogenization Schemes for Dissipative Materials

The prediction of failure processes in composite, heterogeneous materials require multiscale analysis to account for the complex mechanisms and features taking place. Between the different multiscale schemes the more commonly used are those based on homogenization procedures, due to their versatility. In this work a thermodynamically consistent homogenisation based multiscale approach is formulated for modelling thermo-plastic materials. The proposal is valid for arbitrary multiscale procedures, including local or nonlocal methods, and continuum or discontinuum methods in either scale. The necessary and sufficient conditions for fulfilling the thermodynamic consistency are defined. It is demonstrated that the Hill-Mandel variational criterion for homogenization scheme is a necessary, but not a sufficient condition when dissipative material responses are involved at any scale. On this point, the additional condition that needs to be fulfilled is established. The general case of temperature-dependent, higher order elastoplasticity is considered as theoretical framework to account for the material dissipation at micro and macro scales of observation. Additionally, it is shown that the thermodynamic consistency enforces the homogenization of the nonlocal terms of the micro scale’s free energy density; however, this does not necessarily lead to nonlocal effects on the macro scale. Finally, the particular cases of local isothermal elastoplasticity and continuum damage are considered for the purpose of the proposed approach for multiscale homogenizations.Publicado en: Mecánica Computacional vol. XXXV, no. 23Facultad de Ingenierí

Características del abuso de sustancias en la población carcelaria de la provincia de Buenos Aires : Parte I

El abuso de sustancias tiene diversas vinculaciones con las conductas delictivas y constituye tanto un problema de salud pública como un problema de seguridad. El conocimiento de las dimensiones del problema y de las características resulta imprescindible para la planificación de medidas preventivas. Este estudio tiene como meta contribuir al conocimiento del patrón de abuso de sustancias en la población carcelaria bonaerense y detectar características que permitan mejorar el diseño de servicios específicos que promuevan mayor prevención secundaria y terciaria. Los resultados se informan en dos artículos, subtitulado Parte I y Parte II.Facultad de Ciencias Médica

Características del abuso de sustancias en población carcelaria de la provincia de Buenos Aires : Parte II

El abuso de sustancias es un fenómeno heterogéneo y adquiere características según el tipo de consumidor, su medio social y la sustancia disponible. La población carcelaria tiene restricciones y pautas culturales que difícilmente pueden compararse con otros medios. En esta segunda parte del presente estudio -ver la primera parte en Folino & Benitez, número anterior de esta revista científica, los autores se plantean el objetivo de describir el patrón de consumo en una serie de penados drogadependientes.Facultad de Ciencias Médica

Características del abuso de sustancias en la población carcelaria de la provincia de Buenos Aires : Parte I

El abuso de sustancias tiene diversas vinculaciones con las conductas delictivas y constituye tanto un problema de salud pública como un problema de seguridad. El conocimiento de las dimensiones del problema y de las características resulta imprescindible para la planificación de medidas preventivas. Este estudio tiene como meta contribuir al conocimiento del patrón de abuso de sustancias en la población carcelaria bonaerense y detectar características que permitan mejorar el diseño de servicios específicos que promuevan mayor prevención secundaria y terciaria. Los resultados se informan en dos artículos, subtitulado Parte I y Parte II.Facultad de Ciencias Médica

Características del abuso de sustancias en población carcelaria de la provincia de Buenos Aires : Parte II

El abuso de sustancias es un fenómeno heterogéneo y adquiere características según el tipo de consumidor, su medio social y la sustancia disponible. La población carcelaria tiene restricciones y pautas culturales que difícilmente pueden compararse con otros medios. En esta segunda parte del presente estudio -ver la primera parte en Folino & Benitez, número anterior de esta revista científica, los autores se plantean el objetivo de describir el patrón de consumo en una serie de penados drogadependientes.Facultad de Ciencias Médica

Características del abuso de sustancias en población carcelaria de la provincia de Buenos Aires : Parte II

El abuso de sustancias es un fenómeno heterogéneo y adquiere características según el tipo de consumidor, su medio social y la sustancia disponible. La población carcelaria tiene restricciones y pautas culturales que difícilmente pueden compararse con otros medios. En esta segunda parte del presente estudio -ver la primera parte en Folino & Benitez, número anterior de esta revista científica, los autores se plantean el objetivo de describir el patrón de consumo en una serie de penados drogadependientes.Facultad de Ciencias Médica

Fighting Misinformation, Radicalization and Bias in Social Media

Social media have become the ideal place for black hats and malicious individuals to target susceptible users through different attack vectors and then manipulate their opinions and interests. Fake news, radicalization, and pushing bias into the data represent some popular ways noxious users adopt to perpetrate their criminal intents. In this evolving scenario, Artificial Intelligence techniques represent a valuable tool to early detect and mitigate the risk due to the spreading of these emerging attacks. In this work, we describe the Machine Learning based solutions developed to address the problems mentioned above and our current research