Chemistry of pyrrocorphins: synthesis of isobacteriochlorins and pyrrocorphins bearing a methyl group at the meso position between rings A and D

A sigmatropic methyl shift from the angular position C-1 in ring to the position C-20 between rings and constitutes the crucial step in syntheses leading to a 20-methyl-isobacteriochlorin and to 20-methyl-pyrrocorphins which served as substrates in the investigation presented in the accompanying communication.

Crop Yield Responses to Temperature Fluctuations in 19th Century Finland: Provincial Variation in Relation to Climate and Tree Rings

Past agricultural responses to climate variability can helps us to better understand the current and future impacts of climate change on agricultural production. We studied rye (Secale cereale) and barley (Hordeum vulgare) yield responses to temperature fluctuations in Finland during the period 1861–1913. Our analyses demonstrate the high sensitivity of non-industrialised northern agriculture to temperature anomalies. We found evidence of a strong relationship between monthly and seasonal mean temperatures and crop yields. In particular, high spring temperatures were associated with higher yields. Additionally, we tested temperature-sensitive tree-ring series for their value in indicating previous agricultural outputs. The results imply that tree-ring proxies (in particular, maximum latewood density) can provide novel material for studies of historical periods and locations where instrumentally measured climate and harvest data are not available.

Petition der Herren Schusterjungen Münchens an den Magistrat daselbst: Hoher und stellenweiser sehr vortrefflicher Magistrat! Während rings um uns herum diejenigen Bürger, welche sich in den großen Tagen des Februar und März ...

Welsch (Projektbearbeiter): Ätzende Satire von konservativ/reaktionärer Seite auf den Verlauf der Münchener Märzrevolution in Form einer Petition der Schusterjungen zwecks Anerkennung ihrer Verdienste

Stable carbon and oxygen isotopes in tree rings show physiological responses of Pericopsis elata to precipitation in the Congo Basin

In equatorial regions, where tree rings are less distinct or even absent, the response of forests to high-frequency climate variability is poorly understood. We measured stable carbon and oxygen isotopes in anatomically distinct, annual growth rings of four Pericopsis elata trees from a plantation in the Congo Basin, to assess their sensitivity to recorded changes in precipitation over the last 50 y. Our results suggest that oxygen isotopes have high common signal strength (EPS = 0.74), and respond to multi-annual precipitation variability at the regional scale, with low δ18O values (28–29‰) during wetter conditions (1960–1970). Conversely, δ13C are mostly related to growth variation, which in a light-demanding species are driven by competition for light. Differences in δ13C values between fast- and slow-growing trees (c. 2‰), result in low common signal strength (EPS = 0.37) and are driven by micro-site conditions rather than by climate. This study highlights the potential for understanding the causes of growth variation in P. elata as well as past hydroclimatic changes, in a climatically complex region characterized by a bimodal distribution in precipitation.

Concepción heroica Homérica en The Lord of the rings

Fil: Pepe de Suárez, Luz E. A..

Homero y Tolkien. Resonancias homéricas en 'The Lord of the Rings', de Luz Pepe de Suárez

Fil: Errecalde, Alejandro Martín. Universidad Nacional de La Plata. Facultad de Humanidades y Ciencias de la Educación; Argentina.

Homero y Tolkien. Resonancias homéricas en 'The Lord of the Rings', de Luz Pepe de Suárez

Fil: Errecalde, Alejandro Martín. Universidad Nacional de La Plata. Facultad de Humanidades y Ciencias de la Educación; Argentina.

Homero y Tolkien. Resonancias homéricas en 'The Lord of the Rings', de Luz Pepe de Suárez

Fil: Errecalde, Alejandro Martín. Universidad Nacional de La Plata. Facultad de Humanidades y Ciencias de la Educación; Argentina.

Summer rainfall variability in European Mediterranean mountains from the sixteenth to the twentieth century reconstructed from tree rings.

En este trabajo se utilizan dendrocronologías para reconstruir la precipitación estival.

Summer rainfall variability in European Mediterranean mountains from the sixteenth to the twentieth century reconstructed from tree rings.

Estudio dendrocronológico de estructuras arbóreas en alta montaña mediterránea.

Tree rings, carbon dioxide, and climatic change

Tree rings have been used in various applications to reconstruct past climates as well as to assess the effects of recent climatic and environmental change on tree growth. In this paper we briefly review two ways that tree rings provide information about climate change and CO2: (i) in determining whether recent warming during the period of instrumental observations is unusual relative to prior centuries to millennia, and thus might be related to increasing greenhouse gases; and (ii) in evaluating whether enhanced radial growth has taken place in recent decades that appears to be unexplained by climate and might instead be due to increasing atmospheric CO2 or other nutrient fertilization. It is found that a number of tree-ring studies from temperature-sensitive settings indicate unusual recent warming, although there are also exceptions at certain sites. The present tree-ring evidence for a possible CO2 fertilization effect under natural environmental conditions appears to be very limited.