Different families of transport proteins catalyze transmembrane solute translocation, employing different mechanisms and energy sources. Several of these functionally dissimilar proteins nevertheless exhibit similar strutural units, consisting of six tightly packed α‐helices which may comprise all or part of a transmembrane channel. It is now recognized that some of these families arose independently of each other by convergence, while others arose from common precursors by divergence. The former families apparently arose at different times in evolutionary history, in different groups of (...) organisms, employing different routes. (shrink)

En este artículo, deseamos reflexionar sobre un punto neurálgico en nuestra realidad educativa:si no cambiamos nuestra mentalidad docente, si no modificamos nuestro accionar comoprofesores, la brecha entre la realidad social y la burbuja de cristal en la que hemos convertidoa los centros de estudio, escuelas, colegios y universidades será cada vez más grande. Con unasituación como la que planteamos, no es difícil entender algunas de las razones por las que losestudiantes no alcanzan los resultados académicos que nosotros como enseñantes deseamos (...) y,en un porcentaje alto (30 %, según los datos internos de la universidad), cambian de carrera o-lamentablemente- abandonan el proceso educativo. La transformación -necesaria y obligatoria-debe nacer de nosotros; no podemos exigírsela a nuestros estudiantes, pues es nuestraresponsabilidad hacer que sus aprendizajes sean significativos. (shrink)

David Ehrenfeld argues that humanism emphasizes reason at the expense of emotion, and that its narrow focus on the use of reason to serve human interests leads to a dichotomy between man and nature in which ecological factors are subordinated to the satisfaction of human wants. In response, I argue that: (1) humanists stress employment of reflective reason and reason’s interrelations with other aspectsofthe human personality, (2) humanism’s typical commitment to naturalism locates man as part of nature and does not (...) entail an exclusive focus on human interests, and (3) humanism’s commitment to the legitimate sphere of human interests does not entail indifference to nonhuman nature, for a healthy environment is necessary for the long-term satisfaction of human interests. (shrink)

David Ehrenfeld argues that humanism emphasizes reason at the expense of emotion, and that its narrow focus on the use of reason to serve human interests leads to a dichotomy between man and nature in which ecological factors are subordinated to the satisfaction of human wants. In response, I argue that: humanists stress employment of reflective reason and reason’s interrelations with other aspectsofthe human personality, humanism’s typical commitment to naturalism locates man as part of nature and does not entail an (...) exclusive focus on human interests, and humanism’s commitment to the legitimate sphere of human interests does not entail indifference to nonhuman nature, for a healthy environment is necessary for the long-term satisfaction of human interests. (shrink)

Evaluation is, as J. R. Maze has recently suggested, central to the concept of attitude. But it is argued that Maze's noncognitivist analysis of evaluation yields an inadequate account of our ordinary concept of attitude. A criteriological account of evaluation is sketched which allows for an objective dimension to evaluation and hence to attitudes. In the case of attitudes, it is argued that some criteria will be chosen at least in part for their consequences, and hence will not be chosen (...) solely on the basis of interest, preference or affect. (shrink)

In this paper we exhibit a non-finitely based, finitely generated quasi-variety of De Morgan algebras and determine the bottom of the lattices of sub-quasi-varieties of Kleene and De Morgan algebras.

New concepts may prove necessary to profit from the avalanche of sequence data on the genome, transcriptome, proteome and interactome and to relate this information to cell physiology. Here, we focus on the concept of large activity-based structures, or hyperstructures, in which a variety of types of molecules are brought together to perform a function. We review the evidence for the existence of hyperstructures responsible for the initiation of DNA replication, the sequestration of newly replicated origins of replication, cell division (...) and for metabolism. The processes responsible for hyperstructure formation include changes in enzyme affinities due to metabolite-induction, lipid-protein affinities, elevated local concentrations of proteins and their binding sites on DNA and RNA, and transertion. Experimental techniques exist that can be used to study hyperstructures and we review some of the ones less familiar to biologists. Finally, we speculate on how a variety of in silico approaches involving cellular automata and multi-agent systems could be combined to develop new concepts in the form of an Integrated cell (I-cell) which would undergo selection for growth and survival in a world of artificial microbiology. (shrink)

The excellent quality and depth of the various essays make [the book] an invaluable resource....It is likely to become essential reading in its field.—CHOICE.