Free carrier effects in gallium nitride epilayers: the valence band dispersion

The dispersion of the A-valence-band in GaN has been deduced from the observation of high-index magneto-excitonic states in polarised interband magneto-reflectivity and is found to be strongly non-parabolic with a mass in the range 1.2-1.8 m_{e}. It matches the theory of Kim et al. [Phys. Rev. B 56, 7363 (1997)] extremely well, which also gives a strong k-dependent A-valence-band mass. A strong phonon coupling leads to quenching of the observed transitions at an LO-phonon energy above the band gap and a strong non-parabolicity. The valence band was deduced from subtracting from the reduced dispersion the electron contribution with a model that includes a full treatment of the electron-phonon interaction.Comment: Revtex, 4 pages, 5 figure

M & L Jaargang 3/3

RedactioneelMarc De Borgher Het Mechels Broek. [The Mechels Broek]P. Maclot en E. Warmenbol m.m.v. M. De Schampheleire Twee tempels onder de slopershamer: aantekeningen bij de afbraak van het logegebouw van Les Amis du Commerce et la Persévérance Réunis te Antwerpen. [Two temples pulled down: comments on the demolition of the lodge of Les Amis du Commerce et la Persévérance Réunis in Antwerp.]Marcel M. Celis De egyptiserende maçonnieke tempels van de Brusselse loges Les Amis Philantropes en Les Vrais Amis de lUnion et du Progrès Réunis. [The Egyptian masonic temples of the lodges Les Amis philanthropes and Les Vrais Amis de lUnion et du Progrès in Brussels.]B.M.L./Afdeling Architectuur De Hanswijckhoeve. Mechelen-Muizen: restauratie van een 17de-eeuws hoevecomplex. [The Hanswijck farm at Mechelen-Muizen: restoration of a 17th century farmhouse.]SummaryM&L Binnenkran

Do Caves Have Agency?

Recent studies of later prehistoric cave use have stressed the affective qualities of these natural spaces. Certain properties of caves, darkness, constriction and their active geomorphology for example, can lead to caves be characterised as active agents, natural places with profound powers. However, is it really plausible to interpret caves, inanimate geological formations, as active agents? This paper will review arguments on social, environmental and material agency. This will include Structuration theory, with its emphasis on human consciousness as a key aspect of agency, Ingold's 'Dwelling perspective', which allows the possibility of non-human agents, the work of Alfred Gell and Actor Network Theory. Two common threads are drawn from these approaches to describe the way that things act. Things act in accordance with the properties they have and in a way that is structured and enabled by their past history. From this perspective caves can be shown to act and therefore caves would have been perceived as having agency

The Watery Way to the World of the Dead: Underwater Excavations (Old and New) at the Cave of Han-sur-Lesse, Belgium

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