Worldwide evidence of a unimodal relationship between productivity and plant species richness

The search for predictions of species diversity across environmental gradients has challenged ecologists for decades. The humped-back model (HBM) suggests that plant diversity peaks at intermediate productivity; at low productivity few species can tolerate the environmental stresses, and at high productivity a few highly competitive species dominate. Over time the HBM has become increasingly controversial, and recent studies claim to have refuted it. Here, by using data from coordinated surveys conducted throughout grasslands worldwide and comprising a wide range of site productivities, we provide evidence in support of the HBM pattern at both global and regional extents. The relationships described here provide a foundation for further research into the local, landscape, and historical factors that maintain biodiversity.

Efeitos cardiorrespiratórios promovidos pelo posicionamento trendelenburg reverso a cinco e dez graus em bezerros anestesiados pelo sevofluorano: Marcelo Augusto de Araújo. -

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Class Notes for Math 918: Cohen Macaulay Modules, Instructor Roger Wiegand

Topics covered are: Cohen Macaulay modules, zero-dimensional rings, one-dimensional rings, hypersurfaces of finite Cohen-Macaulay type, complete and henselian rings, Krull-Remak-Schmidt, Canonical modules and duality, AR sequences and quivers, two-dimensional rings, ascent and descent of finite Cohen Macaulay type, bounded Cohen Macaulay type.

The last mangroves of Marajo Island - Eastern Amazon: Impact of climate and/or relative sea-level changes

The dynamics, over the last 7500 years, of a mangrove at Marajo Island in northern Brazil were studied by pollen and sedimentary facies analyses using sediment cores. This island, located at the mouth of the Amazon River. is influenced by riverine inflow combined with tidal fluctuations of the equatorial Atlantic Ocean. Herbaceous vegetation intermingled with rainforest dominates the central area of the island, while varzea is the main vegetation type along the littoral. In particular, the modem northeastern coastal zone is covered by a mosaic of dense rainforest, herbaceous vegetation, mangroves, varzea, and restinga. The integration of pollen data and fades descriptions indicates a tidal mud flat colonized by mangroves in the interior of Marajo Island between similar to 7500 cal yr BP and similar to 3200 cal yr BP. During the late Holocene, mangroves retracted to a small area (100-700 m in width) along the northeastern coastal plain. Mangrove expansion during the early and mid Holocene was likely caused by the post-glacial sea-level rise which, combined with tectonic subsidence, led to a rise in tidal water salinity. Salinity must have further increased due to low river discharge resulting from increased aridity during the early and mid Holocene. The shrinking of the area covered by mangrove vegetation during the late Holocene was likely caused by the increase in river discharge during the late Holocene, which has maintained relatively low tidal water salinity in Marajo Island. Tidal water salinity is relatively higher in the northeastern part of the island than in others, due to the southeast-northwest trending current along the littoral. The mixing of marine and riverine freshwater inflows has provided a refuge for mangroves in this area. The increase in flow energy during the last century is related to landward sand migration, which explains the current retraction of mangroves. These changes may indicate an increased exposure to tidal influence driven by the relative sea-level rise, either associated with global fluctuations or tectonic subsidence, and/or by an increase in river water discharge. (C) 2012 Elsevier B.V. All rights reserved.

»How much Brunelleschi?«. Matthew Cohen und sein Phantom-Architekt von San Lorenzo in Florenz

Matthew Cohen hat in San Lorenzo ein mittelalterliches Proportionssystem nachgewiesen und deshalb Brunelleschi als Architekten dieser Kirche ausgeschlossen, da Brunelleschi in Sto. Spirito Proportionen verwendete, die der Renaissanceästhetik entsprechen. Cohen hält den Prior von San Lorenzo, Matteo Dolfini, für den maßgeblichen Architekten. Seine Deutung wird jedoch durch die vorhandenen Dokumente und den Baubefund widerlegt. Ab 1418 wurde – unter der Leitung Brunelleschis! – kein völliger Neubau in Angriff genommen, sondern lediglich ein Anbau, der sich nahtlos an den Altbau von San Lorenzo anfügte. Auf diese Weise erklären sich die mittelalterlichen Proportionen. Erst ab 1465 wurde Alt-San Lorenzo durch einen Neubau ersetzt.

»How much Brunelleschi?«. Matthew Cohen und sein Phantom-Architekt von San Lorenzo in Florenz

Matthew Cohen hat in San Lorenzo ein mittelalterliches Proportionssystem nachgewiesen und deshalb Brunelleschi als Architekten dieser Kirche ausgeschlossen. Würde der Entwurf von Brunelleschi stammen, dann wären - wie in Sto. Spirito - Proportionen zu erwarten, die der Renaissanceästhetik entsprechen. Cohen hält den Prior von San Lorenzo, Matteo Dolfini, für den maßgeblichen Architekten. Seine Deutung wird jedoch durch die vorhandenen Dokumente und den Baubefund widerlegt. Ab 1418 wurde – unter der Leitung Brunelleschis! – kein völliger Neubau in Angriff genommen, sondern lediglich ein Anbau, der sich nahtlos an den Altbau von San Lorenzo anfügte. Auf diese Weise erklären sich die mittelalterlichen Proportionen. Erst ab 1465 wurde Alt-San Lorenzo durch einen Neubau ersetzt.

Zeit ists ... : Gedanken über das jüdische Bildungsproblem des Augenblicks ; an Hermann Cohen

Franz Rosenzweig

Völker, Staaten und Zion : ein Brief an Hermann Cohen u. Bemerkungen zu s. Antwort

von Martin Buber

Worldwide evidence of a unimodal relationship between productivity and plant species richness

The search for predictions of species diversity across environmental gradients has challenged ecologists for decades. The humped-back model (HBM) suggests that plant diversity peaks at intermediate productivity; at low productivity few species can tolerate the environmental stresses, and at high productivity a few highly competitive species dominate. Over time the HBM has become increasingly controversial, and recent studies claim to have refuted it. Here, by using data from coordinated surveys conducted throughout grasslands worldwide and comprising a wide range of site productivities, we provide evidence in support of the HBM pattern at both global and regional extents. The relationships described here provide a foundation for further research into the local, landscape, and historical factors that maintain biodiversity.