Dirac Operators on Quantum Projective Spaces

We construct a family of self-adjoint operators D_N which have compact resolvent and bounded commutators with the coordinate algebra of the quantum projective space CP_q(l), for any l>1 and 0<q<1. They provide 0^+ dimensional equivariant even spectral triples. If l is odd and N=(l+1)/2, the spectral triple is real with KO-dimension 2l mod 8.Comment: 54 pages, no figures, dcpic, pdflate

Automorphisms of associative algebras and noncommutative geometry

A class of differential calculi is explored which is determined by a set of automorphisms of the underlying associative algebra. Several examples are presented. In particular, differential calculi on the quantum plane, the $h$-deformed plane and the quantum group GLpq(2) are recovered in this way. Geometric structures like metrics and compatible linear connections are introduced.Comment: 28 pages, some references added, several amendments of minor importance, remark on modular group in section 8 omitted, to appear in J. Phys.

Quantum Bundle Description of the Quantum Projective Spaces

We realise Heckenberger and Kolb's canonical calculus on quantum projective (n-1)-space as the restriction of a distinguished quotient of the standard bicovariant calculus for Cq[SUn]. We introduce a calculus on the quantum (2n-1)-sphere in the same way. With respect to these choices of calculi, we present quantum projective (N-1)-space as the base space of two different quantum principal bundles, one with total space Cq[SUn], and the other with total space Cq[S^(2n-1)]. We go on to give Cq[CP^n] the structure of a quantum framed manifold. More specifically, we describe the module of one-forms of Heckenberger and Kolb's calculus as an associated vector bundle to the principal bundle with total space Cq[SUn]. Finally, we construct strong connections for both bundles.Comment: 33 pages; minor changes, to appear in Comm. Math. Phy

Out of Amazonia: late-Holocene climate change and the Tupi–Guarani trans-continental expansion

The late Holocene expansion of the Tupi-Guarani languages from southern Amazonia to SE South America constitutes one of the largest expansions of any linguistic family in the world, spanning ~ 4000 km between latitudes 0°S and 35°S at about 2500 yr B.P. However, the underlying reasons for this expansion are a matter of debate. Here, we compare continental-scale palaeoecological, palaeoclimate, and archaeological datasets, to examine the role of climate change in facilitating the expansion of this forestfarming culture. Because this expansion lies within the path of the South American Low-Level Jet, the key mechanism for moisture transport across lowland South America, we were able to explore the relationship between climate change, forest expansion, and the Tupi-Guarani. Our data synthesis shows broad synchrony between late Holocene increasing precipitation and southerly expansion of both tropical forest and Guarani archaeological sites – the southernmost branch of the Tupi-Guarani. We conclude that climate change likely facilitated the agricultural expansion of the Guarani forest-farming culture by increasing the area of forested landscape that they could exploit, showing a prime example of ecological opportunism

Arqueologia e história indígena no Pantanal

O artigo apresenta uma síntese dos dados arqueológicos sobre o Pantanal e o seu entorno, principalmente em Mato Grosso e Mato Grosso do Sul. Elaborado com base na noção de arqueologia como história indígena de longa duração, o artigo considera as trajetórias de estabelecimento e consolidação territorial da ocupação indígena regional, os processos de formação da configuração etnográfica encontrada pelos europeus e os impactos do colonialismo. O principal objetivo consiste em mostrar que a diversidade cultural característica do cenário etnográfico pantaneiro está associada à dinâmica histórica e cultural da ocupação indígena desde períodos anteriores à chegada dos conquistadores e colonizadores de origem europeia.The article presents an overview of the archaeological data on the Pantanal and its surrounding areas, mainly in Mato Grosso and Mato Grosso do Sul. Prepared based on the notion of archeology as long term indigenous history, the article considers the trajectories of territorial establishment and consolidation of the regional indigenous occupation, the formation processes of ethnographic setting found by Europeans and the impact of colonialism. The main objective is to show that cultural diversity characteristic of the Pantanal ethnographic scenario is associated with historical and cultural dynamics of indigenous occupation from periods prior to the arrival of the conquistadors and settlers of European origin

Evidence confirms an anthropic origin of Amazonian Dark Earths

Archaeology of the America

Stomatal response to abscisic acid fed into the xylem of intact Helianthus annuus (L.) plants

The effect of abscisic acid on stomatal apertures of sunflower (Helianthus annuus (L.)) was investigated with a new method for feeding solutions into an attached leaf of an intact plant. Xylem sap was sampled with a Passioura-type pressure chamber. Then it was modified in its composition and fed back into a mature leaf of the plant from which it had been collected before the experiment. Simultaneously, unmodified xylem sap was fed into a control leaf at the same internode. The use of the Passioura-type pressure chamber during feeding, prevented embolisms and ensured minimum dilution of the feeding solution. The effect of feeding was measured by two gas exchange systems, located at the treatment and at the control leaf. During the feeding experiments up to 84% of the water volume transpired by the leaf was substituted by the supplied feeding sap. When feeding xylem sap, to which 2.5 mmol m−3 ABA (physiological range) was added, leaf conductance decreased to a similar value as in drought experiments. A log-linear relationship between the fed ABA-concentration and leaf conductance was observed. Low stomatal con-ductance was dependent on a continuous supply of ABA to the leaf. When total ABA-influx into the leaf was large, either due to long-term feeding of low concentrations or short-term feeding of high concentrations (i) recovery after feeding started later and (ii) the rate of recovery was decreased. Therefore, stomatal responses after short-term and long-term ABA-feeding were dependent on the loading of ABA into the leaf and not only on ABA-concentrations. The effectiveness of fed ABA was also dependent on the light intensity at the fed leaf