Contributions of individual variation in temperature, solar radiation and precipitation to crop yield in the North China Plain, 1961–2003

An understanding of the relative impacts of the changes in climate variables on crop yield can help develop effective adaptation strategies to cope with climate change. This study was conducted to investigate the effects of the interannual variability and trends in temperature, solar radiation and precipitation during 1961–2003 on wheat and maize yields in a double cropping system at Beijing and Zhengzhou in the North China Plain (NCP), and to examine the relative contributions of each climate variable in isolation. 129 climate scenarios consisting of all the combinations of these climate variables were constructed. Each scenario contained 43 years of observed values of one variable, combined with values of the other two variables from each individual year repeated 43 times. The Agricultural Production Systems Simulator (APSIM) was used to simulate crop yields using the ensemble of generated climate scenarios. The results showed that the warming trend during the study period did not have significant impact on wheat yield potential at both sites, and only had significant negative impact on maize yield potential at Beijing. This is in contrast with previous results on effect of warming. The decreasing trend in solar radiation had a much greater impact on simulated yields of both wheat and maize crops, causing a significant reduction in potential yield of wheat and maize at Beijing. Although decreasing trends in rainfed yield of both simulated wheat and maize were found, the substantial interannual variability of precipitation made the trends less prominent.     

X-ray absorption contrast images of binary chemical reactions

Low-divergence synchrotron-sourced X-rays enable a radiographic imaging scheme for full characterization of binary chemical reactions and characterization by type of more complex reactions, in situ, in diamond anvil cells (DAC). Spatially resolved reactants are induced to react by laser heating of their interface. The spatially intermediate products are observed through X-ray absorption contrast. Limits to the technique include the ability to maintain controlled experiment geometry during compression and the ability to resolve chemical differences between reactants and products by X-ray absorption. The ability to make in situ observations at experimental pressure and temperature obviates the problem with quenching techniques for capturing liquid compositions in experiments with dimensions smaller than the diffusion length during quenching time. Partially molten Fe-alloy systems, of poor quenchability, are examined at DAC pressures and temperatures for relevance to Earth's core constitution and evolution. Determinations of eutectic melting in Fe–FeS match known results. Of the probable light elements that may alloy with Fe in the Earth's liquid outer core, Fe–FeS experiments show only modest quenching problems, but C and Si alloy experiments are highly vulnerable to quenching artifacts. The observed reactivity of FeS, Fe₃C, FeSi, and FeO(OH) with Fe in DAC makes the observed non-reactivity between Fe and FeO more significant, reducing the probability that oxygen alone is the major alloy in Earth's molten outer core.     

Zur Alpensynthese

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Functional morphology of Grammatodon inaequivalvis (Goldfuss) and implications for evolutionary pathways in arcoidean bivalves

Secondary soft-bottom dwellers evolved several times in the Arcoida. These include semi-infaunal endobyssate taxa and free-burrowing species. The Jurassic arcoid bivalve Grammatodon inaequivalvis (Goldfuss, 1837) is remarkable for showing different sculptures on its left and right valve. A functional analysis of the shell points to a reclining mode of life on soft bottoms. This interpretation is corroborated by the occurrence of this species in very fine-grained sediments, and by taphonomic patterns such as “butterflied” preservation. It is proposed here that this species was resting on its left valve on the sediment, probably without byssal attachment. This reclining mode of life of G. inaequivalvis was hitherto undescribed from soft-bottom dweller arcoid bivalves.     

Shock barometry of the Siljan impact structure,Sweden

Abstract– The Siljan impact structure in Sweden is the largest confirmed impact structure in Western Europe. Despite this, the structure has been poorly studied in the past, and detailed studies of shock metamorphic features in the target lithologies are missing. Here, we present the results of a detailed systematic search for shock metamorphic features in quartz grains from 73 sampled localities at Siljan. At 21 localities from an area approximately 20 km in diameter located centrally in the structure, the orientations of 2851 planar deformation feature sets in 1179 quartz grains were measured. Observations of shatter cones outside of the zone with shocked quartz extend the total shocked area to approximately 30 km in diameter. The most strongly shocked samples, recording pressures of up to 20 GPa, occur at the very central part of the structure, and locally in these samples, higher pressures causing melting conditions in the affected rocks were reached. Pressures recorded in the studied samples decrease outwards from the center of the structure, forming roughly circular envelopes around the proposed shock center. Based on the distribution pattern of shocked quartz at Siljan, the original transient cavity can be estimated at approximately 32–38 km in diameter. After correcting for erosion, we conclude that the original rim to rim diameter of the Siljan crater was somewhere in the size range 50–90 km.     

Preservation of biological information in thermal spring deposits: developing a strategy for the search for fossil life on Mars

Current interpretations of the early history of Mars suggest many similarities with the early Earth and therefore raise the possibility that the Archean and Proterozoic history of life on Earth could have a counterpart on Mars. Terrestrial experience suggests that, with techniques that can be employed remotely, ancient springs, including thermal springs, could well yield important information. By delivering water and various dissolved species to the sunlit surface of Mars, springs very likely created an environment suitable for life, which could have been difficult, if not impossible, to attain elsewhere. The chemical and temperature gradients associated with thermal springs sort organisms into sharply delineated, distinctive and different communities, and so diverse organisms are concentrated into relatively small areas in a predictable and informative fashion. A wide range of metabolic strategies are concentrated into small areas, thus furnishing a useful and representative sampling of the existing biota. Mineral-charged springwaters frequently deposit chemical precipitates of silica and/or carbonate which incorporate microorganisms and preserve them as fossils. The juxtaposition of stream valley headwaters with volcanoes and impact craters on Mars strongly implies that subsurface heating of groundwater created thermal springs. On Earth, thermal springs create distinctive geomorphic features and chemical signatures which can be detected by remote sensing. Spring deposits can be quite different chemically from adjacent rocks. Individual springs can be hundreds of meters wide, and complexes of springs occupy areas up to several kilometers wide. Benthic microbial mats and the resultant stromatolites occupy a large fraction of the available area. The relatively high densities of fossils and microbial mat fabrics within these deposits make them highly prospective in any search for morphological evidence of life, and there are examples of microbial fossils in spring deposits as old as 300 Myr.     

The Evolution of the Interstellar Medium over Cosmic Time

C23 UV spectroscopy of the PG1159-type star NGC7094 C26 Variations of the radio synchrotron spectral index in the interstellar medium of M33 C38 Angular Momentum Evolution of Young Brown Dwarfs and Low Mass Stars C48 The radio halo of the nearby starburst galaxy NGC 253 C95 Signatures of early metal enrichment in Damped-Lyman Alpha systems C113 CO 4 → 3 and [CI] 1 → 0 in the centers of NGC4945 and Circinus C115 Ratio of atomic and molecular gas and gravitational stabilty in the disk of M51 C130 The Interstellar Mediumat Early Cosmic Times: Molecular Gas in Distant Quasar Host Galaxies C188 Probing the interstellar medium in distant galaxies with SPICA/ESI C191 The evolution of spectral energy distributions of galaxies over cosmic times C197 Observations of 60Fe in the Galaxy with INTEGRAL/SPI C204 Evolution of Interstellar Clouds in a hot Gas Environment C205 The effect of clouds in a galactic wind on the evolution of gas-rich dwarf galaxies C206 Energy and element deposit into the interstellar medium during the lives of massive stars C209 The distribution and kinematics of massive stars in the inner Galaxy mapped with SPI/INTEGRAL 26Al 1.8 MeV line observations C213 PDR modelling of the Galactic FIR line emission C239 Towards a complete picture of the molecular ISM in local Luminous Infrared Galaxies: first results from the JCMT/IRAM line survey C242 The Search for the Very High-redshift Tail of Submillimeter Galaxies     

Variations in 24-μm morphologies among galaxies in the Spitzer Infrared Nearby Galaxies Survey: new insights into the Hubble sequence

To study the distribution of star formation and dust emission within nearby galaxies, we measured five morphological parameters in the 3.6- and 24-μm wavebands for 65 galaxies in the Spitzer Infrared Nearby Galaxies Survey (SINGS) and eight galaxies that were serendipitously observed by SINGS. The morphological parameters demonstrate strong variations along the Hubble sequence, including statistically significant differences between S0/a-Sab and Sc-Sd galaxies. Early-type galaxies are generally found to be compact, centralized, symmetric sources in the 24-μm band, while late-type galaxies are generally found to be extended, asymmetric sources. These results suggest that the processes that increase the real or apparent sizes of galaxies' bulges also lead to more centralized 24-μm dust emission. Several phenomena, such as strong nuclear star formation, Seyfert activity, or outer ring structures, may cause galaxies to deviate from the general morphological trends observed at 24 μm. We also note that the 24-μm morphologies of Sdm-Im galaxies are quite varied, with some objects appearing very compact and symmetric but others appearing diffuse and asymmetric. These variations reflect the wide variation in star formation in irregular galaxies as observed at other wavelengths. The variations in the 24-μm morphological parameters across the Hubble sequence mirror many of the morphological trends seen in other tracers of the ISM and in stellar emission. However, the 24-μm morphological parameters for the galaxies in this sample do not match the morphological parameters measured in the stellar wavebands. This implies that the distribution of dust emission is related to but not equivalent to the distribution of stellar emission.     

Mass models of the Milky Way

A parametrized model of the mass distribution within the Milky Way is fitted to the available observational constraints. The most important single parameter is the ratio of the scalelength R _d* of the stellar disc to R ₀. The disc and bulge dominate v _c( R ) at R ≲ R ₀ only for R _d,*/ R ₀≲0.3. Since the only knowledge we have of the halo derives from studies like the present one, we allow it to contribute to the density at all radii. When allowed this freedom, however, the halo causes changes in assumptions relating to R  ≪  R ₀ to affect profoundly the structure of the best-fitting model at R  ≫  R ₀. For example, changing the disc slightly from an exponential surface-density profile significantly changes the form of v _c( R ) at R  ≫  R ₀, where the disc makes a negligible contribution to v _c. Moreover, minor changes in the constraints can cause the halo to develop a deep hole at its centre that is not physically plausible. These problems call into question the proposition that flat rotation curves arise because galaxies have physically distinct haloes rather than outwards-increasing mass-to-light ratios.   The mass distribution of the Galaxy and the relative importance of its various components will remain very uncertain until more observational data can be used to constrain mass models. Data that constrain the Galactic force field at z ≳ R and at R  >  R ₀ are especially important.