Search

After fire, recolonization implies a process of structural and functional organisation to reach a new state of equilibrium with the environment. Vertical structuration can be analysed through the evolution of the total leaf area distribution in the vertical profile. The change through time in the vertical gradients of the leaf mean area and the stomatdal density and size, among other things, are useful too to interpret this process. Space occupation patterns can be analysed through the evolution of the foliage projective coverage and the species spatial dependence (regarded as contacts between pairs of species), considering a reticle covering the surface to be studied. A set of models may be useful to carry out this analysis. Changes in time of the basal area, density and stem diameter, and diametric classes distribution of stems are also useful to analyse and interpret the changes taking place after fire. Some theoretical problems in relation to these different approaches are discussed in this paper. Examples focusing on a Quercus coccifera garrigue chronosequence are presented to illustrate some remarkable features., Sala Anna, Sabaté Santiago, Gracia Carlos. Structure and organisation of a Quercus coccifera garrigue after fire. In: Ecologia mediterranea, tome 13 n°4, 1987. Influence of fire on the stability of mediterranean forest ecosystems. Giens (France) 23-26/03/1987. pp. 99-110.

Summer drought is a characteristic trait of Mediterranean climates and can limit primary production. The holm oak (Quercus ilex L.) forest at the Prades Experimental Complex of Catchments (PECC, NE Spain) was managed by clearcutting until the 1950s. As a result of this practice, the forest has a high density (13000 stems ha(-1)) that is causing growth stagnation and intense competition for water. A thinning experiment was conducted to release resources, reduce stem competition and improve forest productivity. Minirhizotrons were installed in two plots in each of the thinned and control stands and fine root dynamics quantified to a soil depth of 60 cm over a 2-year period (June 1994-May 1996). Soil water content was higher and soil water penetrated deeper in the soil (30-50 cm) in the thinned plots than in the control plots. In the control plots, soil temperature did not vary substantially with depth (mean = 11.65 degrees C), whereas soil temperature was higher in shallow horizons compared with deep horizons in the thinned plots. Mean soil temperature was one degree higher in the thinned plots than in the control plots (12.9 versus 11.9 degrees C). There were always more roots in the top 20 cm of soil in thinned plots than in control plots. In the thinned plots, more than 50% of root density (root no. cm(-2)) was located in the top 20 cm of soil, whereas root density never reached 50% in the 0-20 cm soil layer of the control plots. Roots longevity varied from 35 to 471 days, and there were significant differences between soil depths. Root longevity was greater in the control plots than in the thinned plots.

We used minirhizotrons to determine the vertical distribution of fine roots in a holm oak (Quercus ilex L.) forest in a typical Mediterranean area over a 3-year period (June 1994-March 1997). We measured fine root density (number of roots per unit area), fine root length density (length of roots per unit area), fine root area index (area of roots per unit area) and fine root mean diameter. Variables were pooled for each 10-cm depth interval to a depth of 60 cm. Fine roots tended to decrease with increasing depth except between 0 and 10 cm, where the values of all fine root variables were less than in the 10-cm stratum below. Fine root vertical distribution was compared with soil water content and soil temperature at different depths in the soil profile.

En este artículo se propone una revisión personal de la investigación lingüística de los últimos 25 años sobre el egipcio antiguo, la lengua hablada y escrita en Egipto desde el origen de la civilización egipcia escrita (hacia 3150 a. Jc.) hasta la desaparición del copto como lengua viva (siglo XVII d. Jc.), la lengua humana documentada durante más tiempo. Con este fin, se revisarán las principales corrientes teóricas y su relación con la enseñanza del antiguo egipcio en ámbito universitario. Mediante el análisis de la bibliografía más relevante de este periodo, se comentan cuatro líneas de investigación productivas: forma y función; documentos y lengua; léxico y gramática; y metalingüística en el Egipto antiguo. El artículo finaliza con un breve comentario sobre la necesidad de más estudios basados en corpora en el futuro, en lugar de los basados en marcos teóricos para la interpretación del egipcio antiguo. This article provides a personal overview of the last 25-year linguistic research on ancient Egyptian, the language spoken and written in Egypt since the origin of the written Egyptian civilization (c. 3150 BC) until the disappearance of Coptic as a living language (17th century AC), the longest-attested human language. With this purpose, the main theoretical approaches and their relationship to teaching ancient Egyptian at the university are reviewed. Through the analysis of the more relevant bibliography of the period, four productive research lines are discussed: form and function; documents and the language; lexicon and grammar; and ancient Egyptian metalinguistics. The article ends with a short comment on the need of more corpus-based studies in the future instead of theoretically-based frameworks for interpreting the ancient Egyptian language.

La presente revisión fue realizada con el objetivo de ampliar los conocimientos sobre el envejecimiento cutáneo y los tratamientos restitutivos empleados en la cirugía plástica ocular, especialmente la bioestimulación cutánea con plasma rico en plaquetas, como alternativa novedosa de rejuvenecimiento periocular. Se realizó una búsqueda bibliográfica amplia y actualizada en bases de datos que ofrece Infomed, como Ebsco, Hinari, Pubmed, Google académico y textos básicos de Oftalmología y Cirugía Estética. El plasma rico en plaquetas es un preparado biológico efectivo para la bioestimulación cutánea; incrementa la producción de colágeno; elastina y ácido hialurónico, proporciona una piel con más brillo, mejor textura, hidratación y elasticidad; presenta múltiples ventajas y mínimas complicaciones, lo que contribuye a elevar la calidad de vida de los pacientes.

Homogeneous stable suspensions obtained by dispersing dry TiO2 nanoparticles in pure ethylene glycol were prepared and studied. Two types of nanocrystalline structure were analyzed, namely anatase and rutile phases, which have been characterized by scanning electron microscopy. The rheological behavior was determined for both nanofluids at nanoparticle mass concentrations up to 25%, including flow curves and frequency-dependent storage and loss moduli, using a cone-plate rotational rheometer. The effect of temperature over these flow curve tests at the highest concentration was also analyzed from 283.15 to 323.15 K. Furthermore, the influence of temperature, pressure, nanocrystalline structure, and concentration on the volumetric properties, including densities and isobaric thermal expansivities, were also analyzed.

absent