The ~11 yr Solar Cycle

Sunspot numbers and shifts in their distribution display a period of approximately 11 yr, a value sometimes uncritically applied to other measures of solar activity, direct and indirect, including the 10.7 cm radio flux, the inflow of galactic cosmic rays, solar flare frequency, terrestrial weather, and components of space climate, with a possible resulting loss of information. The ruling (Babcock) hypothesis and its derivatives link the sunspot cycle to dynamo processes mediated by differential solar rotation, but despite 60 years of observation and analysis the ~11 yr periodicity remains difficult to model; the possible contribution of planetary dynamics is also still controversial. The various solar sequences that genuinely display an ~11 yr cycle stand to benefit from an understanding of its periodicity that goes beyond statistical rigour. The outcome could ironically prompt the demotion of sunspots from their dominant historical role in favour of other possible indicators of solar cyclicity, such as the solar wind flux and its isotopic signatures, even if they are less accessible

Core to solar wind: a stepwise model for heating the solar corona

Operating experience from fusion research shows how Spitzer resistivity may render ohmic heating in the chromosphere self limiting and thus serve to define the lower margin of the transition region. Its upper margin is at about 6000 K, where radiative cooling of He:H plasma decelerates sharply. The third and last stage in the proposed scheme is expansion into the tenuous plasma of space, which leads to the acceleration of ions to high energies, long recorded by spacecraft instruments. There is thus dynamic continuity all the way from the solar interior, the energy source for spinning columns in the Rayleigh Benard setting of the convection zone, to the coronal exhalation of the solar wind, a finding which should benefit the analysis of space weather, witness the association between helium in the solar wind and the incidence of coronal mass ejections

Geometry, kinematics and rates of deformation in a normal fault segment boundary, central Greece

The geometry, kinematics and rates of deformation within a fault segment boundary between the ends of two major active normal fault segments have been investigated through examination of a faulted 126 ka marine terrace. Slip‐vector azimuths defined by striations on the faults indicate N‐S extension on c. E‐W faults, sub‐parallel to those from earthquake focal mechanisms, together with significant and contemporaneous E‐W extension on c. N‐S faults. Summed rates of E‐W extension along a c. 550 m transect (0.17 mm/yr) are comparable with those for N‐S extension (0.20 mm/yr) along a c. 350 m transect. Our observations show that distributed non‐plane strain extension occurs in fault segment boundaries and this should be noted when studying fault‐tip fracture toughness and regional deformation rates

Structural Characterisation of Metabolites from Pholiota spumosa (Basidiomycetes)

Three compounds of different biosynthetic origin were isolated from the fruiting bodies of the gilled mushroom Pholiota spumosa (Basidiomycetes, Strophariaceae). Fasciculol E, a lanostane triterpenoid conjugated to a depsipeptide unit, was isolated for the first time from genus Pholiota. In addition, the first isolation of putrescine-1,4-dicinnamamide as a natural compound is reported: its structure was established by single crystal X-ray diffraction, and by spectroscopic methods. Crystallographic analysis indicated the presence of a co-crystallised related dicinnamamide, namely the new compound (E)-2,3-dehydroputrescine-1,4-dicinnamamide, whose occurrence was confirmed by LC-MS analysis. An interesting evolutionary issue arises, following the observation that the cinnamamides produced by Pholiota spumosa bear an unsubstituted benzene ring, contrarily to those found in plants, which have always phenolic functionalities, and as such perform a variety of biological roles

Structural Characterisation of Metabolites from Pholiota spumosa (Basidiomycetes)

Three compounds of different biosynthetic origin were isolated from the fruiting bodies of the gilled mushroom Pholiota spumosa (Basidiomycetes, Strophariaceae). Fasciculol E, a lanostane triterpenoid conjugated to a depsipeptide unit, was isolated for the first time from genus Pholiota. In addition, the first isolation of putrescine-1,4-dicinnamamide as a natural compound is reported: its structure was established by single crystal X-ray diffraction, and by spectroscopic methods. Crystallographic analysis indicated the presence of a co-crystallised related dicinnamamide, namely the new compound (E)-2,3-dehydroputrescine-1,4-dicinnamamide, whose occurrence was confirmed by LC-MS analysis. An interesting evolutionary issue arises, following the observation that the cinnamamides produced by Pholiota spumosa bear an unsubstituted benzene ring, contrarily to those found in plants, which have always phenolic functionalities, and as such perform a variety of biological roles

Elaia, Pergamon's maritime satellite:The rise and fall of an ancient harbour city shaped by shoreline migration

Throughout human history, communication and trade have been key to society. Because maritime trade facilitated the rapid transportation of passengers and freight at relatively low cost, harbours became hubs for traffic, trade and exchange. This general statement holds true for the Pergamenian kingdom, which ruled wide parts of today's western Turkey during Hellenistic times. Its harbour, located at the city of Elaia on the eastern Aegean shore, was used extensively for commercial and military purposes. This study reconstructs the coastal evolution in and around the ancient harbour of Elaia and compares the observed environmental modifications with archaeological and historical findings. We use micropalaeontological, sedimentological and geochemical proxies to reconstruct the palaeoenvironmental dynamics and evolution of the ancient harbour. The geoarchaeological results confirm the archaeological and historical evidence for Elaia's primacy during Hellenistic and early Roman times, and the city's gradual decline during the late Roman period. Furthermore, our study demonstrates that Elaia holds a unique position as a harbour city during ancient times in the eastern Aegean region, because it was not greatly influenced by the high sediment supply associated with river deltas. Consequently, no dredging of the harbour basins is documented, creating exceptional geo-bioarchives for palaeoenvironmental reconstructions

Terrestrial modification of the Ivuna meteorite and a reassessment of the chemical composition of the CI type specimen

The rare CI carbonaceous chondrites are the most aqueously altered and chemically primitive meteorites but due to their porous nature and high abundance of volatile elements are susceptible to terrestrial weathering. The Ivuna meteorite, type specimen for the CI chondrites, is the largest twentieth-century CI fall and probably the CI chondrite least affected by terrestrial alteration that is available for study. The main mass of Ivuna (BM2008 M1) has been stored in a nitrogen atmosphere at least since its arrival at the Natural History Museum (NHM), London, in 2008 (70 years after its fall) and could be considered the most pristine CI chondrite stone. We report the mineralogy, petrography and bulk elemental composition of BM2008 M1 and a second Ivuna stone (BM1996 M4) stored in air within wooden cabinets. We find that both Ivuna stones are breccias consisting of multiple rounded, phyllosilicate-rich clasts that formed through aqueous alteration followed by impact processing. A polished thin section of BM2008 M1 analysed immediately after preparation was found to contain sulphate-bearing veins that formed when primary sulphides reacted with oxygen and atmospheric water. A section of BM1996 M4 lacked veins but had sulphate grains on the surface that formed in ≤6 years, ∼3 times faster than previous reports for CI chondrite sections. Differences in the extent of terrestrial alteration recorded by BM2008 M1 and BM1996 M4 probably reflect variations in the post-recovery curation history of the stones prior to entering the NHM collection, and indicate that where possible pristine samples of hydrated carbonaceous should be kept out of the terrestrial environment in a stable atmosphere to avoid modification. The bulk elemental composition of the two Ivuna stones show some variability due to their heterogeneous nature but in general are similar to previous analyses of CI chondrites. We combine our elemental abundances with literature values to calculate a new average composition for the Ivuna meteorite, which we find is in good agreement with existing compilations of element compositions in the CI chondrites and the most recent solar photospheric abundances

Quaternary glacial history of the Mediterranean mountains

Glacial and periglacial landforms are widespread in the mountains of the Mediterranean region. The evidence for glacial and periglacial activity has been studied for over 120 years and it is possible to identify three phases of development in this area of research. First, a pioneer phase characterized by initial descriptive observations of glacial landforms; second, a mapping phase whereby the detailed distribution of glacial landforms and sediments have been depicted on geomorphological maps; and, third, an advanced phase characterized by detailed understanding of the geochronology of glacial sequences using radiometric dating alongside detailed sedimentological and stratigraphical analyses. It is only relatively recently that studies of glaciated mountain terrains in the Mediterranean region have reached an advanced phase and it is now clear from radiometric dating programmes that the Mediterranean mountains have been glaciated during multiple glacial cycles. The most extensive phases of glaciation appear to have occurred during the Middle Pleistocene. This represents a major shift from earlier work whereby many glacial sequences were assumed to have formed during the last cold stage. Glacial and periglacial deposits from multiple Quaternary cold stages constitute a valuable palaeoclimatic record. This is especially so in the Mediterranean mountains, since mountain glaciers in this latitudinal zone would have been particularly sensitive to changes in the global climate system. © 2006 Edward Arnold (Publishers) Ltd