How stable are 20th century calibration models? A high-resolution summer temperature reconstruction for the eastern Swiss Alps back to A.D. 1580 derived from proglacial varved sediments

We found a significant positive correlation between local summer air temperature (May-September) and the annual sediment mass accumulation rate (MAR) in Lake Silvaplana (46°N, 9°E, 1800 m a.s.l.) during the twentieth century (r = 0.69, p < 0.001 for decadal smoothed series). Sediment trap data (2001-2005) confirm this relation with exceptionally high particle yields during the hottest summer of the last 140 years in 2003. On this base we developed a decadal-scale summer temperature reconstruction back to AD 1580. Surprisingly, the comparison of our reconstruction with two other independent regional summer temperature reconstructions (based on tree-rings and documentary data) revealed a significant negative correlation for the pre-1900 data (ie, late ‘Little Ice Age’). This demonstrates that the correlation between MAR and summer temperature is not stable in time and the actualistic principle does not apply in this case. We suggest that different climatic regimes (modern/‘Little Ice Age’) lead to changing state conditions in the catchment and thus to considerably different sediment transport mechanisms. Therefore, we calibrated our MAR data with gridded early instrumental temperature series from AD 1760-1880 (r = -0.48, p < 0.01 for decadal smoothed series) to properly reconstruct the late LIA climatic conditions. We found exceptionally low temperatures between AD 1580 and 1610 (0.75°C below twentieth-century mean) and during the late Maunder Minimum from AD 1680 to 1710 (0.5°C below twentieth-century mean). In general, summer temperatures did not experience major negative departures from the twentieth-century mean during the late ‘Little Ice Age’. This compares well with the two existing independent regional reconstructions suggesting that the LIA in the Alps was mainly a phenomenon of the cold season.

Non-Hodgkin lymphoma incidence in the Swiss HIV Cohort Study before and after highly active antiretroviral therapy

OBJECTIVE: To assess the long-term effect of HAART on non-Hodgkin lymphoma (NHL) incidence in people with HIV (PHIV). DESIGN: Follow-up of the Swiss HIV Cohort Study (SHCS). METHODS: Between 1984 and 2006, 12 959 PHIV contributed a total of 75 222 person-years (py), of which 36 787 were spent under HAART. Among these PHIV, 429 NHL cases were identified from the SHCS dataset and/or by record linkage with Swiss Cantonal Cancer Registries. Age- and gender-standardized incidence was calculated and Cox regression was used to estimate hazard ratios (HR). RESULTS: NHL incidence reached 13.6 per 1000 py in 1993-1995 and declined to 1.8 in 2002-2006. HAART use was associated with a decline in NHL incidence [HR = 0.26; 95% confidence interval (CI), 0.20-0.33], and this decline was greater for primary brain lymphomas than other NHL. Among non-HAART users, being a man having sex with men, being 35 years of age or older, or, most notably, having low CD4 cell counts at study enrollment (HR = 12.26 for < 50 versus >or= 350 cells/microl; 95% CI, 8.31-18.07) were significant predictors of NHL onset. Among HAART users, only age was significantly associated with NHL risk. The HR for NHL declined steeply in the first months after HAART initiation (HR = 0.46; 95% CI, 0.27-0.77) and was 0.12 (95% CI, 0.05-0.25) 7 to10 years afterwards. CONCLUSIONS: HAART greatly reduced the incidence of NHL in PHIV, and the influence of CD4 cell count on NHL risk. The beneficial effect remained strong up to 10 years after HAART initiation.

Patterns of recurrence of early breast cancer according to estrogen receptor status: a therapeutic target for a quarter of a century

The current therapeutic strategy in breast cancer is to identify a target, such as estrogen receptor (ER) status, for tailoring treatments. We investigated the patterns of recurrence with respect to ER status for patients treated in two randomized trials with 25 years' median follow-up. In the ER-negative subpopulations most breast cancer events occurred within the first 5-7 years after randomization, while in the ER-positive subpopulations breast cancer events were spread through 10 years. In the ER-positive subpopulation, 1 year endocrine treatment alone significantly prolonged disease-free survival (DFS) with no additional benefit observed by adding 1 year of chemotherapy. In the small ER-negative subpopulation chemo-endocrine therapy had a significantly better DFS than endocrine alone or no treatment. Despite small numbers of patients, "old-fashioned" treatments, and competing causes of treatment failure, the value of ER status as a target for response to adjuvant treatment is evident through prolonged follow-up.

Arctic Winds in the “Twentieth Century Reanalysis”

Climate in the European part of the Arctic underwent a rapid warming between the 1910s and the 1930s. Previous studies have addressed the role of atmospheric circulation in this period based on geopotential height fields because observations of upper-level winds in the Arctic are rare. Here we analyse winds over the Arctic and specifically over Spitsbergen in the “Twentieth Century Reanalyses” (20CR). We compare in situ upper-air wind measurements performed in 1912 and 1913 in Spitsbergen with six-hourly 20CR data. Furthermore, we compare monthly-to-seasonal 20CR winds at 700 hPa over the European Arctic with statistically reconstructed winds at 3 km altitude. Finally, we analyse long-term trends in Arctic winds in 20CR. The general agreement between observed upper-air winds and 20CR on the day-to-day scale is rather poor, which is not surprising given the paucity of observations in the Arctic at that time that constrain 20CR. In contrast, the seasonally averaged winds (which represent a larger spatial scale) in 20CR compare well with statistically reconstructed winds. The analysis of long term near-surface wind time series in 20CR shows arguably artificial trends from 1871 to around the 1950s over sparsely observed regions, particularly oceanic regions. Densely observed regions such as Europe or the USA show no such trends. This analysis shows that great care needs to be taken when working with 20CR in the Arctic and other sparsely observed regions.

Possible earthquake trigger for 6th century mass wasting deposit at Lake Ohrid (Macedonia/Albania)

Abstract. Lake Ohrid shared by the Republics of Albania and Macedonia is formed by a tectonically active graben within the south Balkans and suggested to be the oldest lake in Europe. Several studies have shown that the lake provides a valuable record of climatic and environmental changes and a distal tephrostratigraphic record of volcanic eruptions from Italy. Fault structures identified in seismic data demonstrate that sediments have also the potential to record tectonic activity in the region. Here, we provide an example of linking seismic and sedimentological information with tectonic activity and historical documents. Historical documents indicate that a major earthquake destroyed the city of Lychnidus (today: city of Ohrid) in the early 6th century AD. Multichannel seismic profiles, parametric sediment echosounder profiles, and a 10.08m long sediment record from the western part of the lake indicate a 2m thick mass wasting deposit, which is tentatively correlated with this earthquake. The mass wasting deposit is chronologically well constrained, as it directly overlays the AD472/AD 512 tephra. Moreover, radiocarbon dates and cross correlation with other sediment sequences with similar geochemical characteristics of the Holocene indicate that the mass wasting event took place prior to the onset of the Medieval Warm Period, and is attributed it to one of the known earthquakes in the region in the early 6th century AD.

Lake-level rise in the late Pleistocene and active subaquatic volcanism since the Holocene in Lake Kivu; East African Rift

The history of Lake Kivu is strongly linked to the activity of the Virunga volcanoes. Subaerial and subaquatic volcanoes, in addition to lake-level changes, shape the subaquatic morphologic and structural features in Lake Kivu's Main Basin. Previous studies revealed that volcanic eruptions blocked the former outlet of the lake to the north in the late Pleistocene, leading to a substantial rise in the lake level and subsequently the present- day thermohaline stratification. Additional studies have speculated that volcanic and seismic activities threaten to trigger a catastrophic release of the large amount of gases dissolved in the lake. The current study presents a bathymetric mapping and seismic profiling survey that covers the volcanically active area of the Main Basin at a resolution that is unprecedented for Lake Kivu. New geomorphologic features identified on the lake floor can accurately describe related lake-floor processes for the first time. The late Pleistocene lowstand is observed at 425 m depth, and volcanic cones, tuff rings, and lava flows observed above this level indicate both subaerial and subaquatic volcanic activities during the Holocene. The geomorphologic analysis yields new implications on the geologic processes that have shaped Lake Kivu's basin, and the presence of young volcanic features can be linked to the possibility of a lake overturn.

Remote Effects Modulating the Spin Equilibrium of the Resting State of Cytochrome P450cam –An Investigation Using Active Site Analogues

The crystal structure of the resting state of cytochrome P450cam (CYP101), a heme thiolate protein, shows a cluster of six water molecules in the substrate binding pocket, one of which is coordinating to iron(III) as sixth ligand. The resting state is low-spin and changes to high-spin when substrate camphor binds and H2O is removed. In contrast to the protein, previously synthesised enzyme models such as H2O[BOND]FeIII(porph)(ArS−) were shown to be purely high-spin. Iron(S−)porphyrins with different distal sites mimicking proposed remote effects have been prepared and studied by cw-EPR. The results indicate that the low-spin of the resting state of P450cam is due to the fact that the water molecule coordinating to iron has an OH−-like character because of hydrogen bonding and polarisation of the water cluster, respectively.

The origin of the low-spin character of the resting state of cytochrome P450cam investigated by means of active site analogues

Crown-capped iron(S−) porphyrins 1·H2O and 2·H2O and their corresponding Ba2+ complexes have been prepared as active site analogues of the resting state of cytochrome P450cam. cw-EPR studies and electronic structure calculations at the density functional theory (DFT) level of model systems suggest a functional role of the water cluster of P450cam.

Narrow dust jets in a diffuse gas coma: a natural product of small active regions on comets

Comets often display narrow dust jets but more diffuse gas comae when their eccentric orbits bring them into the inner solar system and sunlight sublimates the ice on the nucleus. Comets are also understood to have one or more active areas covering only a fraction of the total surface active with sublimating volatile ices. Calculations of the gas and dust distribution from a small active area on a comet’s nucleus show that as the gas moves out radially into the vacuum of space it expands tangentially, filling much of the hemisphere centered on the active region. The dust dragged by the gas remains more concentrated over the active area. This explains some puzzling appearances of comets having collimated dust jets but more diffuse gaseous atmospheres. Our test case is 67P/Churyumov–Gerasimenko, the Rosetta mission target comet, whose activity is dominated by a single area covering only 4% of its surface.