The adaptive dynamics of niche constructing traits in spatially subdivided populations: evolving posthumous extended phenotypes.

Niche construction, by which organisms modify the environment in which they live, has been proposed to affect the evolution of many phenotypic traits. But what about the evolution of a niche constructing trait itself, whose expression changes the pattern of natural selection to which the trait is exposed in subsequent generations? This article provides an inclusive fitness analysis of selection on niche constructing phenotypes, which can affect their environment from local to global scales in arbitrarily spatially subdivided populations. The model shows that phenotypic effects of genes extending far beyond the life span of the actor can be affected by natural selection, provided they modify the fitness of those individuals living in the future that are likely to have inherited the niche construction lineage of the actor. Present benefits of behaviors are thus traded off against future indirect costs. The future costs will generally result from a complicated interplay of phenotypic effects, population demography and environmental dynamics. To illustrate these points, I derive the adaptive dynamics of a trait involved in the consumption of an abiotic resource, where resource abundance in future generations feeds back to the evolutionary dynamics of the trait.

DOI: The "Big Brother" in the dissemination of scientific documentation

Rapid growth in the availability and use of digital documents has prompted the development of instruments to handle them. A most important example of these instruments are digital identifiers, which provide a codification system that allows digital items, usually up to the level of a computer file, to be singled out and located. Digital identifiers make up standardized global systems applied to specific products or areas. They are part of the very many identifiers developed to handle large numbers of items and large amounts of information for transactional purposes, which often have a global span. Digital identifiers include the ubiquitous Global Trade Item Number (GTIN), a code that unequivocally identifies trade items all around the world. The GTIN can take on several configurations depending on its application. These include: EAN-13, EAN-8, EAN-14, and UCC-12. EAN-13 is the code used for retail products in order to facilitate trade at the point of sale; its widely known symbol or graphical form is the EAN/UPC-13 bar code...

Brain-derived neurotrophic factor-like immunoreactivity is localized mainly in small sensory neurons of rat dorsal root ganglia.

Brain-derived neurotrophic factor (BDNF) is a protein capable of supporting the survival and fiber outgrowth of peripheral sensory neurons. It has been argued that histological detection of BDNF has proven difficult because of its low molecular weight and relatively low expression. In the present study we report that rapid removal of dorsal root ganglia (DRG) from the rat, followed by rapid freezing and appropriate fixation with cold acetone, preserves BDNF in situ without altering protein antigenicity. Under these conditions, specific BDNF-like immunoreactivity was detected in DRG both in vivo and in vitro. During DRG development in vivo, BDNF-like immunoreactivity (BDNF-LI) was observed only in a subset of sensory neurons. BDNF-LI was confined to small neurons, after neurons became morphologically distinct on the basis of size. BDNF-L immunoprecipitate was detected only in neuronal cells, and not in satellite or Schwann cells. While in vivo BDNF localization was restricted to small neurons, practically all neurons in DRG cell culture displayed BDNF-LI. Small or large primary afferent neurons exhibited a faint but clear BDNF-LI during the whole life span of cultures. Again, non-neuronal cells were devoid of BDNF-LI. In conclusion, in DRG in vivo, specific BDNF-LI was confined to small B sensory neurons. In contrast, all DRG sensory neurons displayed BDNF-LI in vitro. The finding that BDNF expressed in all DRG neurons in vitro but not in vivo suggests that BDNF expression may be modulated by environmental factors.

Tecnologies de la informació (barates) aplicades a les persones amb necessitats especials

As a consequence of the lack of adequate support, many people with physical or sensorial difficulties frequently encounter obstacles to using information technologies. Today equipment and programmes exist for overcoming these barriers, but frequently they are too expensive for the economic limitations of our smaller libraries, document centres, archives, museums, etc. An inexpensive alternative can be found in the accessibility options incorporated into Windows. While these probably do not offer the best or the most adequate solutions, it can be argued that, they are an acceptable alternative, considering existing budget restrictions. This text describes the functionalities of Windows XP, grouping them according to the type of difficulty addressed (visual, motor or auditory) in order to facilitate access to the application.

Spatio-temporal Brain Dynamics Mediating Post-error Behavioral Adjustments.

Optimal behavior relies on flexible adaptation to environmental requirements, notably based on the detection of errors. The impact of error detection on subsequent behavior typically manifests as a slowing down of RTs following errors. Precisely how errors impact the processing of subsequent stimuli and in turn shape behavior remains unresolved. To address these questions, we used an auditory spatial go/no-go task where continual feedback informed participants of whether they were too slow. We contrasted auditory-evoked potentials to left-lateralized go and right no-go stimuli as a function of performance on the preceding go stimuli, generating a 2 × 2 design with "preceding performance" (fast hit [FH], slow hit [SH]) and stimulus type (go, no-go) as within-subject factors. SH trials yielded SH trials on the following trials more often than did FHs, supporting our assumption that SHs engaged effects similar to errors. Electrophysiologically, auditory-evoked potentials modulated topographically as a function of preceding performance 80-110 msec poststimulus onset and then as a function of stimulus type at 110-140 msec, indicative of changes in the underlying brain networks. Source estimations revealed a stronger activity of prefrontal regions to stimuli after successful than error trials, followed by a stronger response of parietal areas to the no-go than go stimuli. We interpret these results in terms of a shift from a fast automatic to a slow controlled form of inhibitory control induced by the detection of errors, manifesting during low-level integration of task-relevant features of subsequent stimuli, which in turn influences response speed.

The future of longevity: background and perspectives

In many developed countries, including Switzerland, the ongoing increase in life expectancy is driven by the mortality decline among older persons. This has important consequences for both the provision of health care and the management of pension funds. In this context, the Swiss Federal Office of Statistics mandated a small group of experts to provide a critical review on the future evolution of mortality in developed countries. The report starts with an analysis of the past trends in life expectancy. Longevity is defined here as the duration (or the length) of life as observed in population or in individuals. The oldest and still most used indicators of longevity are life expectancy at birth (LE0) at a population level, and maximum life span (MLS) at the individual level (page 9) and in healthy life expectancy (page 19). A discussion on the future evolution of mortality and health is then presented (page 27). A set of recommendations is finally proposed (page 39).