Perfils: Evert Jan Baerends i la densitat electrònica de molècules

Evert Jan Baerends és catedràtic de la Universitat Lliure d’Amsterdam i de la Universitat de Ciència i Tecnologia de Pohang de Corea del Sud. És un dels impulsors de l’Amsterdam Density Functional Program System, la teoria que ha revolucionat el camp de la química teòrica i computacional moderna. La importància de la densitat electrònica es va fer patent l’any 1964, quan Walter Kohn (Premi Nobel 1998) va demostrar que totes les propietats de les molècules es poden caracteritzar a partir del coneixement de la densitat. Ha assistit al Girona Seminar, convidat per l’Institut de Química Computacional de la UdG

Las lenguas como instrumento de la política exterior: caso de estudio "La francofonía"

"A lo largo de la historia la distribución de las lenguas a escala planetaria, ha traducido la distribución del poder en el mundo", es a partir de este concepto, que trataremos de ver hasta qué medida las políticas de defensa y proliferación ejecutadas por el gobierno Francés, en lo que respecta a su lengua, son consideradas como simple proteccionismo, o a su vez son verdaderamente políticas de estado dictadas desde las más altas esferas del poder, considerando que la cultura y el lenguaje pueden ser tomados como mecanismos de aculturización. Para Huntington, coexisten dos formas de reagrupamientos, a excepción de las construcciones regionales como Europa. La primera es la recomposición de las relaciones internacionales según las pertenencias a las mismas civilizaciones; la segunda como el caso de la Francofonía, es la de los conjuntos neoculturales, íntercivilizaciones, de uniones lingüísticas, constituidas alrededor de idiomas compartidos, fenómeno que parece ser ignorado o considerado como efimero y sin importancia. Para este trabajo tomaremos como punto de referencia la Ley del 4 de Agosto de 1997, "Ley TOUBON", que lleva el nombre del entonces Ministro de Cultura francés, y que fue dictada con el fin de garantizar a los ciudadanos la utilización del idioma en todo el territorio Nacional, y favorecer al plurilingüismo en el ámbito internacional.

In vitro cumulative gas production techniques: History, methodological considerations and challenges

Methodology used to measure in vitro gas production is reviewed to determine impacts of sources of variation on resultant gas production profiles (GPP). Current methods include measurement of gas production at constant pressure (e.g., use of gas tight syringes), a system that is inexpensive, but may be less sensitive than others thereby affecting its suitability in some situations. Automated systems that measure gas production at constant volume allow pressure to accumulate in the bottle, which is recorded at different times to produce a GPP, and may result in sufficiently high pressure that solubility of evolved gases in the medium is affected, thereby resulting in a recorded volume of gas that is lower than that predicted from stoichiometric calculations. Several other methods measure gas production at constant pressure and volume with either pressure transducers or sensors, and these may be manual, semi-automated or fully automated in operation. In these systems, gas is released as pressure increases, and vented gas is recorded. Agitating the medium does not consistently produce more gas with automated systems, and little or no effect of agitation was observed with manual systems. The apparatus affects GPP, but mathematical manipulation may enable effects of apparatus to be removed. The amount of substrate affects the volume of gas produced, but not rate of gas production, provided there is sufficient buffering capacity in the medium. Systems that use a very small amount of substrate are prone to experimental error in sample weighing. Effect of sample preparation on GPP has been found to be important, but further research is required to determine the optimum preparation that mimics animal chewing. Inoculum is the single largest source of variation in measuring GPP, as rumen fluid is variable and sampling schedules, diets fed to donor animals and ratios of rumen fluid/medium must be selected such that microbial activity is sufficiently high that it does not affect rate and extent of fermentation. Species of donor animal may also cause differences in GPP. End point measures can be mathematically manipulated to account for species differences, but rates of fermentation are not related. Other sources of inocula that have been used include caecal fluid (primarily for investigating hindgut fermentation in monogastrics), effluent from simulated rumen fermentation (e.g., 'Rusitec', which was as variable as rumen fluid), faeces, and frozen or freeze-dried rumen fluid (which were both less active than fresh rumen fluid). Use of mixtures of cell-free enzymes, or pure cultures of bacteria, may be a way of increasing GPP reproducibility, while reducing reliance on surgically modified animals. However, more research is required to develop these inocula. A number of media have been developed which buffer the incubation and provide relevant micro-nutrients to the microorganisms. To date, little research has been completed on relationships between the composition of the medium and measured GPP. However, comparing GPP from media either rich in N or N-free, allows assessment of contributions of N containing compounds in the sample. (c) 2005 Published by Elsevier B.V.

Self-assembly of beta-turn forming synthetic tripeptides into supramolecular beta-sheets and amyloid-like fibrils in the solid state

We have described here the self-assembling properties of the synthetic tripeptides Boc-Ala(1)-Aib(2) -Val (3)-OMe 1, BocAla(l)-Aib(2)-Ile(3)-OMe 2 and Boc-Ala(l)-Gly(2)-Val(3)-OMe 3 (Aib=alpha-arnino isobutyric acid, beta-Ala=beta-alanine) which have distorted beta-turn conformations in their respective crystals. These turn-forming tripeptides self-assemble to form supramolecular beta-sheet structures through intermolecular hydrogen bonding and other noncovalent interactions. The scanning electron micrographs of these peptides revealed that these compounds form amyloid-like fibrils, the causative factor for many neurodegenerative diseases including Alzheimer's disease, Huntington's disease and Prion-related encephalopathies. (C) 2004 Elsevier Ltd. All rights reserved.

Chess Endgame News

This paper notes FIDE's 75-move rule (9.6b) and suggests some implications. It reviews two endgame-table initiatives associated with the 50-move rule. One is Huntington's mainly sub-6-man multi-valued DTM50 EGTs implemented in HASKELL. The other is Ronald de Man's WDL' and DTZ50' EGTs which introduce a 5-way evaluation of positions, and ascribe a depth to decisive positions which are not 50-move-rule wins or losses. There is also some first detail about the Lomonosov '7-man DTM EGT' team, and comments on reactions to 'Haworth's Law'.

Depth to mate and the 50-move rule

The most popular endgame tables (EGTs) documenting ‘DTM’ Depth to Mate in chess endgames are those of Eugene Nalimov but these do not recognise the FIDE 50-move rule ‘50mr’. This paper marks the creation by the first author of EGTs for sub-6-man (s6m) chess and beyond which give DTM as affected by the ply count pc. The results are put into the context of previous work recognising the 50mr and are compared with the original unmoderated DTM results. The work is also notable for being the first EGT generation work to use the functional programming language HASKELL.

Cannabinoids and tremor induced by motor-related disorders: friend or foe?

Tremor arises from an involuntary, rhythmic muscle contraction/relaxation cycle and is a common disabling symptom of many motor-related diseases such as Parkinson disease, multiple sclerosis, Huntington disease, and forms of ataxia. In the wake of anecdotal, largely uncontrolled, observations claiming the amelioration of some symptoms among cannabis smokers, and the high density of cannabinoid receptors in the areas responsible for motor function, including basal ganglia and cerebellum, many researchers have pursued the question of whether cannabinoid-based compounds could be used therapeutically to alleviate tremor associated with central nervous system diseases. In this review, we focus on possible effects of cannabinoid-based medicines, in particular on Parkinsonian and multiple sclerosis-related tremors and the common probable molecular mechanisms. While, at present, inconclusive results have been obtained, future investigations should extend preclinical studies with different cannabinoids to controlled clinical trials to determine potential benefits in tremor.

Sermon notes and manuscript communities

Any reader of manuscript catalogues knows how common the unhelpfully vague entry “sermon notes, 17th-century” can be. This essay explores whether we can find in sermon notes the kinds of textual communities that have been found through the reconstruction of other routes of manuscript circulation. It will unpick what those laconic catalogue entries mean, and distinguish the different kinds of sermon notes found in our archival collections (some derived from the original preacher, some from hearers, some from readers of manuscript and printed copies). The physical forms of different sorts of “sermon notes” alerts us to the different types of authors who created these manuscripts, and the different purposes involved in preserving an oration in textual form, purposes which included fostering the creation and maintenance of communal identities among the self-consciously godly or Catholic recusants.