Parietal lobe contribution to spatial processing: evidence from brain tumour patients

The main aim of this research project was to compare the effects of a parietal lesion in brain tumour patients with effects of prefrontal and premotor lesions on a number of processes related to the ability to operate in near space. More specifically, we studied the effects of a brain tumour lesion on two basic processes such as the ability to (i) reach an object in space and (ii) to integrate spatiotemporal information in a prediction task. Then, two more cognitive processes were investigated, namely (iii) the ability to perform visuospatial transformations and (iv) to encode and retrieve the spatial relation between letters in a string. To that purpose, an anatomical group study approach was used. The method allowed us to better localize the relevant systems involved on the processes investigated..

Sporadic randomness, Maxwell's Demon and the Poincare' recurrence times

In the case of fully chaotic systems the distribution of the Poincare'recurrence times is an exponential whose decay rate is the Kolmogorov-Sinai(KS) entropy.We address the discussion of the same problem, the connection between dynamics and thermodynamics,in the case of sporadic randomness,using the Manneville map as a prototype of this class of processes. We explore the possibility of relating the distribution of Poincare' recurrence times to `thermodynamics',in the sense of the KS entropy,also in the case of an inverse power law. This is the dynamic property that Zaslavsly [Phys.Today(8), 39(1999)] finds to be responsible for a striking deviation from ordinary statistical mechanics under the form of Maxwell's Demon effect. We show that this way of estabi- lishing a connection between thermodynamics and dynamics is valid only in the case of strong chaos. In the case of sporadic randomness, resulting at long times in the Levy diffusion processes,the sensitivity to initial conditions is initially an inverse pow erlaw,but it becomes exponential in the long-time scale, whereas the distribution of Poincare times keeps its inverse power law forever. We show that a nonextensive thermodynamics would imply the Maxwell's Demon effect to be determined by memory and thus to be temporary,in conflict with the dynamic approach to Levy statistics. The adoption of heuristic arguments indicates that this effect,is possible, as a form of genuine equilibrium,after completion of the process of memory erasure.Comment: 13 pages,two-column,latex-revtex,2 figures(2 files .eps

The application of GMOs in agriculture and in food production for a better nutrition: two different scientific points of view

This commentary is a face-to-face debate between two almost opposite positions regarding the application of genetic engineering in agriculture and food production. Seven questions on the potential benefits of the application of genetic engineering in agriculture and on the potentially adverse impacts on the environment and human health were posed to two scientists: one who is sceptical about the use of GMOs in Agriculture, and one who views GMOs as an important tool for quantitatively and qualitatively improving food production.Research at the Universitat de Lleida is supported by MICINN, Spain (BFU2007-61413); European Union Framework 7 Program-SmartCell Integrated Project 222716; European Union Framework 7 European Research Council IDEAS Advanced Grant Program-BIOFORCE; COST Action FA0804: Molecular farming: plants as a production platform for high value proteins; Centre CONSOLIDER on Agrigenomics funded by MICINN, Spain

In the search for the low-complexity sequences in prokaryotic and eukaryotic genomes: how to derive a coherent picture from global and local entropy measures

We investigate on a possible way to connect the presence of Low-Complexity Sequences (LCS) in DNA genomes and the nonstationary properties of base correlations. Under the hypothesis that these variations signal a change in the DNA function, we use a new technique, called Non-Stationarity Entropic Index (NSEI) method, and we prove that this technique is an efficient way to detect functional changes with respect to a random baseline. The remarkable aspect is that NSEI does not imply any training data or fitting parameter, the only arbitrarity being the choice of a marker in the sequence. We make this choice on the basis of biological information about LCS distributions in genomes. We show that there exists a correlation between changing the amount in LCS and the ratio of long- to short-range correlation

When non-extensive entropy becomes extensive

Tsallis' non-extensive entropy $S_q$ enables us to treat both a power and exponential evolutions of underlying microscopic dynamics on equal footing by adjusting the variable entropic index $q$ to proper one $q^*$. We propose an alternative constraint of obtaining the proper entropic index $q^*$ that the non-additive conditional entropy becomes additive if and only if $q=q^*$ in spite of that the associated system cannot be decomposed into statistically independent subsystems. Long-range (time) correlation expressed by $q$-exponential function is discussed based on the nature that $q$-exponential function cannot be factorized into independent factors when $q \ne 1$.Comment: 8 pages, no figure, LaTeX2e, elsart. submit to Physica