Encounters in Music Cultures of Aztec and Early Colonial Times

Dieser Artikel untersucht die sozio-politischen und religiösen Dimensionen des Musizierens und Klangerzeugens über den Vergleich zweier kulturell unterschiedlicher, aber nah beieinander liegenden Zeitabschnitte an ein und demselben Ort: dem Tal von Mexiko. Zunächst werden die Praktiken der Azteken zur Ausübung musikalischer Dominanz und Kontrolle über die von ihnen eroberten Gesellschaften der späten post-klassischen Periode Mesoamerikas (1325 bis 1521 n. Chr.) untersucht. Darauf folgend werden die spanischen Strategien der musikalischen Dominanz und Kontrolle über die eroberten Azteken der frühen Kolonialzeit (1521 bis 1600) beleuchtet und dem aztekischen Modell gegenübergestellt. Der Artikel fragt nach den Unterschieden und strukturellen Ähnlichkeiten in der musikalischen Eroberung

No experimental evidence for local competition in the nestling phase as a driving force for density-dependent avian clutch size

1. In birds, local competition for food between pairs during the nestling phase may affect nestling growth and survival. A decrease in clutch size with an increase in breeding density could be an adaptive response to this competition. To investigate whether breeding density causally affected the clutch size of great tits (Parus major), we manipulated breeding density in three out of eight study plots by increasing nest-box densities. We expected clutch size in these plots to be reduced compared to that in control plots. 2. We analysed both the effects of variation in annual mean density (between-year comparisons) and experimental density (within-year comparison between plots) on clutch size variation, the occurrence of second broods and nestling growth. We examined within-female variation in clutch size to determine whether individual responses explain the variation over years. 3. Over the 11 years, population breeding density increased (from 0·33 to 0·50 pairs ha–1) while clutch size and the occurrence of second broods decreased (respectively from 10·0 to 8·5 eggs and from 0·39 to 0·05), consistent with a negative density-dependent effect for the whole population. Nestling growth showed a declining but nonsignificant trend over years. 4. The decline in population clutch size over years was primarily explained by changes occurring within individuals rather than selective disappearance of individuals laying large clutches. 5. Within years, breeding density differed significantly between manipulated plots (0·16 pairs ha–1 vs. 0·77 pairs ha–1) but clutch size, occurrence of second broods and nestling growth were not affected by the experimental treatment, resulting in a discrepancy between the effects of experimental and annual variation in density on reproduction. 6. We discuss two hypotheses that could explain this discrepancy: (i) the decline in breeding performance over time was not due to density, but resulted from other, unknown factors. (ii) Density did cause the decline in breeding performance, but this was not due to local competition in the nestling phase. Instead, we suggest that competition acting in a different phase (e.g. before egg laying or after fledgling) was responsible for the density effect on clutch size among years.

Embryonic stem cells in bone tissue engineering

Due to increased life expectancy of humans the number of patients with age related skeletal compliciations has increased. These patients but also patients suffering from complications due to trauma or disease often need surgical interventions in which additional bone is required for optimal recovery. Currently the most frequently used bone replacement is autologous or allogeneic bone, but both methods have their drawbacks

Controlling the Size of Popcorn

We present a thermo-statistical model of popcorn production and propose a way to control the final size of the popcorn by monitoring only the chamber pressure.Comment: 6 pages; revision (typo and minor content corrections

Impact of Interaction Range and Curvature on Crystal Growth of Particles Confined to Spherical Surfaces

When colloidal particles form a crystal phase on a spherical template, their packing is governed by the effective interaction between them and the elastic strain of bending the growing crystal. For example, if growth commences under appropriate conditions, and the circular crystal that forms reaches a critical size, growth continues by incorporation of defects to alleviate elastic strain. Recently it was found experimentally that, if defect formation is somehow not possible, the crystal instead continues growing in ribbons that protrude from the original crystal. Here we report on computer simulations in which we observe both the formation of ribbons at short interaction ranges and packings that incorporate defects if the interaction is longer-ranged. The ribbons only form above some critical crystal size, below which the nucleus is roughly spherically shaped. We find that the scaling of the critical crystal size differs slightly from the one proposed by the Manoharan group, and reason this is because the actual process is a two-step heterogeneous nucleation of ribbons on top of roughly circular crystals.Comment: 24 pages, 11 figure