Global properties of an age-structured virus model with saturated antibody immune response, multi-target cells and general incidence rate

Some viruses, such as human immunodeficiency virus, can infect several types of cell populations. The age of infection can also affect the dynamics of infected cells and production of viral particles. In this work, we study a virus model with infection-age and different types of target cells which takes into account the saturation effect in antibody immune response and a general non-linear infection rate. We construct suitable Lyapunov functionals to show that the global dynamics of the model is completely determined by two critical values: the basic reproduction number of virus and the reproductive number of antibody response

Educational challenges in the protection of biodiversity

[Resumo] O proceso de empobrecemento da biodiversidade da Terra é, xuntamente co Cámbio Climático, a maior ameaza ambiental que enfrenta a humanidade na actualidade, e vai condicionar gravemente as suas expectivas de benestar futuro. Neste artigo sinálase por qué a biodiversidade é importante, por que se degrada, as potenciais consecuencias desa degradación, así como as dificultades que plantexa tanto sensibilizar á opinión pública sobre a gravidade do problema como comprometela a poñer freo a este proceso e cambiar a tendencia. Apóntanse algunhas posibilidades e liñas de traballo para que a educación ambiental, en canto instrumento social, poida constribuir neste ámbito. Xurdida para facer fronte á crise ambiental, a educación ambiental atopouse desde os seus inicios con desafíos que sobardan as súas posibilidades reais como ferramenta para o cámbio. Porén, conta con instrumentos, recursos e experiencia para facer aportacións relevantes no camiño de tentar cambiar as tendencias ecocidas.[Abstract] The process of impoverishment of the biodiversity of the Earth is, along with that of Climate Change, the greatest environmental threat which faces humanity at the present time, and which is going to seriously condition our expectations for future well-being. This article aims to point out why biodiversity is important, why it is degraded, the potential outcome of such degradation, as well as the difficulties involved both in informing public opinion about the serious nature of the problem and about involving the public in the checking of this process and in a change of such a tendency. Some possibilities and lines of work will be suggested for environmental education which, as a social instrument, could make acontribution in this field. As something which has arisen from the need to face up to this environmental crisis, environmental education has faced, sinced its origins, a series of challenges which which outreach its real possibilities as an instrument for change.As such, it relies upon instruments, resources and experience in order to make relevant contributions as a means of trying to change the tendencies undergone

Lakhota language and identity in Pine Ridge, SD

The Lakhota language, like many other Native American languages, faces a decline in young speakers. Can the culture exist independently of a language and can the people have the same feeling of belonging to it even after the language has been lost? The following study analyzes the relation of language and identity in a situation when most members of a tribe are no longer able to speak the language. It is based on interviews with 52 participants carried out on Pine Ridge Reservation. The study compares the opinions of speakers of the language with the non-speakers with the objective to find out what alternative signs of identity people use when they are not able to speak the language. The analysis focuses on the attitude to the language, it is trying to answer the question whether it is necessary to speak the language to be Lakhota and what do the people think about the eventuality that the language might disappear completely

Unha nova cultura forestal para a sociedade galega: o proxecto do Parque forestal de Liáns

[Resumo] Preséntase un proxecto de Parque Forestal. O deseño e concepción do proxecto baséase no aproveitamento dunhas circunstancias favorables especiais: a existencia dunha finca de propiedade pública, xestionada pola administración forestal, situada a escasa distancia do centro de referencia para a educación ambiental en Galicia, o CEIDA, e dotada de infraestruturas e equipamentos susceptibles de uso social e educativo. Resáltase o potencial do sitio para converterse nun parque periurbano nun contexto favorable en canto á dimensión dos posibles beneficiarios e aos recursos de dinamización dispoñibles. Explórase o potencial ambiental do enclave, capaz de permitir a réplica de realidades forestais moi diversas e posuidor, ao tempo, de valores de alta calidade conservativa. En definitiva, preséntase un proxecto que ten como base crear un parque forestal periurbano con vocación de uso social, que compaxina con ese uso o carácter de equipamento ambiental de referencia para promover unha nova cultura do bosque na sociedade galega, e que pretende complementar eses dous usos coa contribución á conservación da diversidade biolóxica, ser un referente de investigación ambiental e forestal, e abrir a Galicia ao mundo a través da cooperación internacional.[Abstract] The forestry park concept is presented as a design project based on the favourable circumstances which exists on public property land and managed by forestry administration. The land in question is closely situated to the reference centre of environmental education in Galicia, CEIDA, which can provide the infrastructure and equipment necessary for social and educational use. This area has the potential to attract public interest as a periphery park and broaden the educative resources available locally. Furthermore this land has environmental potential providing both forestry replications and high quality conservational values. In summary, this project promotes the periphery forest garden as an important instrument for social and educational use, providing the environmental equipment needed to encourage the new forest culture within galician society. The oportunity value of the site is explored as a reference to biodiversity conservation and environmental forest research it is designed too, as a tool to introduce Galicia to the world prometing international cooperatio

Revitalization of Lakhota language on Pine Ridge Reservation : waiting to hit rock bottom

Lakhota is one of a few North American Indian languages that still counts the speakers of the language in the thousands. However, their age structure is alarming as there are very few speakers younger than seventeen and even the age group of today's parents usually do not speak the language. Various examples of successful language revitalization prove that it is not impossible to restart inter-generational mother-tongue transmission but they prove at the same time that it is a very difficult task. The following study analyzes the situation of Lakhota language teaching at schools, the role of schools and involvement of the community in language conservation issues. It also focuses on Lakhota opinions about standardized testing and immersion. My research was conducted on the Pine Ridge Reservation and it is based on interviews with 52 participants. It compares opinions of teachers and parents of school children with the objective to find out whether the teaching of Lakhota is adequate with respect to the current condition the language is in