Buttress form of the central African rain forest tree Microberlinia bisulcata, and its possible role in nutrient acquisition

Buttressing is a trait special to tropical trees but explanations for its occurrence remain inconclusive. The two main hypotheses are that they provide structural support and/or promote nutrient acquisition. Studies of the first are common but the second has received much less attention. Architectural measurements were made on adult and juvenile trees of the ectomycorrhizal species Microberlinia bisulcata, in Korup (Cameroon). Buttressing on this species is highly distinctive with strong lateral extension of surface roots of the juveniles leading to a mature buttress system of a shallow spreading form on adults. This contrasts with more vertical buttresses, closer to the stem, found on many other tropical tree species. No clear relationship between main buttress and large branch distribution was found. Whilst this does not argue against the essential structural role of buttresses for these very large tropical trees, the form on M. bisulcata does suggest a likely second role, that of aiding nutrient acquisition. At the Korup site, with its deep sandy soils of very low phosphorus status, and where most nutrient cycling takes place in a thin surface layer of fine roots and mycorrhizas, it appears that buttress form could develop from soil-surface root exploration for nutrients by juvenile trees. It may accordingly allow M. bisulcata to attain the higher greater competitive ability, faster growth rate, and maximum tree size that it does compared with other co-occurring tree species. For sites across the tropics in general, the degree of shallowness and spatial extension of buttresses of the dominant species is hypothesized to increase with decreasing nutrient availability.

Transmembrane tumor necrosis factor is a potent inducer of colitis even in the absence of its secreted form

Tumor necrosis factor (TNF) is cleaved proteolytically from a 26-kilodalton transmembrane precursor protein into secreted 17-kilodalton monomers. Transmembrane (tm) and secreted trimeric TNF are biologically active and may mediate distinct activities. We assessed the consequences of a complete inhibition of TNF processing on the course of colitis in recombination activating gene (RAG)2 -/- mice on transfer of CD4 CD45RB hi T cells.

Form und Filter - Algorithmen der Bilderverarbeitung und Stilanalyse

Die Grundbegriffe Wölfflins lassen sich mit Hilfe digitaler Algorithmen nachmodellieren. Welches Wissen wird damit gewonnen? Auch Wölfflin hat auf mediale Veränderungen reagiert, indem er die Doppel-Projektion von Dias in den binären Differenzen der Grundbegriffe nachbildete. Sie lesen der Projektion zweier Bilder eine historische Differenz aus, die für die Disziplin der Kunstgeschichte grundlegend ist. Ein digitale Nachbildung dieser Differenz wäre tautologisch: sie würde ein gewusstes Wissen wiederholen. Fruchtbar wird der Einsatz digitaler Algorithmen dann, wenn sie nicht nur etwas bekanntes abbilden, sondern wenn man fragt, zu welcher "methodischen Grenzerweiterung" sie beitragen könnten.

Matching form with content

Successful computer-supported distance education requires that its enabling technologies are accessible and usable anywhere. They should work seamlessly inside and outside the information superhighway, wherever the target learners are located, without obtruding on the learning activity. It has long been recognised that the usability of interactive computer systems is inversely related to the visibility of the implementing technologies. Reducing the visibility of technology is especially challenging in the area of online language learning systems, which require high levels of interactivity and communication along multiple dimensions such as speaking, listening, reading and writing. In this article, the authors review the concept of invisibility as it applies to the design of interactive technologies and appliances. They describe a specialised appliance matched to the requirements for distance second language learning, and report on a successful multi-phase evaluation process, including initial field testing at a Thai open university.

Matching form with content

Successful computer-supported distance education requires that its enabling technologies are accessible and usable anywhere. They should work seamlessly inside and outside the information superhighway, wherever the target learners are located, without obtruding on the learning activity. It has long been recognised that the usability of interactive computer systems is inversely related to the visibility of the implementing technologies. Reducing the visibility of technology is especially challenging in the area of online language learning systems, which require high levels of interactivity and communication along multiple dimensions such as speaking, listening, reading and writing. In this article, the authors review the concept of invisibility as it applies to the design of interactive technologies and appliances. They describe a specialised appliance matched to the requirements for distance second language learning, and report on a successful multi-phase evaluation process, including initial field testing at a Thai open university.

Porcine ulcerative dermatitis syndrome in sows: a form of vesicular cutaneous lupus erythematosus?

Severe ulcerative lesions were observed in the skin of two sows in a herd of 540 hybrid sows. Annular to polycyclic, severe crusting dermal ulcerations were found on the abdomen and flanks; moderate lesions were also found at the base of the tail and on the perineum. The lesions were histologically characterised as cell-poor interface dermatitis and folliculitis, basal cell vacuolisation, vesicle formation at the dermal-epidermal junction and serocellular crusts. A subepidermal mild to moderate band, characterised as a mixed inflammatory infiltrate, was present. A test for antinuclear antibodies was negative; however, immunofluorescence testing revealed a linear pattern of IgG precipitation in the skin. Staphylococcus hyicus was demonstrated in the serocellular crusts of one sow. Treatment with antibiotics, topical antiseptics and corticosteroids did not improve the sows' condition. Porcine circovirus and porcine respiratory and reproductive syndrome virus were not isolated from samples taken at postmortem examination. The observed gross lesions, the absence of response to treatment and the exclusion of other skin diseases suggested that the sows were affected with porcine ulcerative dermatitis syndrome.

The EU’s Trouble with Mashups: From Disabling to Enabling a Digital Art Form

New tools for editing of digital images, music and films have opened up new possibilities to enable wider circles of society to engage in ’artistic’ activities of different qualities. User-generated content has produced a plethora of new forms of artistic expression. One type of user-generated content is the mashup. Mashups are compositions that combine existing works (often) protected by copyright and transform them into new original creations. The European legislative framework has not yet reacted to the copyright problems provoked by mashups. Neither under the US fair use doctrine, nor under the strict corset of limitations and exceptions in Art 5 (2)-(3) of the Copyright Directive (2001/29/EC) have mashups found room to develop in a safe legal environment. The contribution analyzes the current European legal framework and identifies its insufficiencies with regard to enabling a legal mashup culture. By comparison with the US fair use approach, in particular the parody defense, a recent CJEU judgment serves as a comparative example. Finally, an attempt is made to suggest solutions for the European legislator, based on the policy proposals of the EU Commission’s “Digital Agenda” and more recent policy documents (e.g. “On Content in the Digital Market”, “Licenses for Europe”). In this context, a distinction is made between non-commercial mashup artists and the emerging commercial mashup scene.

Analytical form of the Probability Density Function of travel times in rectangular zone with Tchebyshev’s metric

Geometrical dependencies are being researched for analytical representation of the probability density function (pdf) for the travel time between a random, and a known or another random point in Tchebyshev’s metric. In the most popular case - a rectangular area of service - the pdf of this random variable depends directly on the position of the server. Two approaches have been introduced for the exact analytical calculation of the pdf: Ad-hoc approach – useful for a ‘manual’ solving of a specific case; by superposition – an algorithmic approach for the general case. The main concept of each approach is explained, and a short comparison is done to prove the faithfulness.