Persistent multi-decadal Greenland temperature fluctuation through the last millennium

Future Greenland temperature evolution will affect melting of the ice sheet and associated global sea-level change. Therefore, understanding Greenland temperature variability and its relation to global trends is critical. Here, we reconstruct the last 1,000 years of central Greenland surface temperature from isotopes of N₂ and Ar in air bubbles in an ice core. This technique provides constraints on decadal to centennial temperature fluctuations. We found that northern hemisphere temperature and Greenland temperature changed synchronously at periods of ~20 years and 40–100 years. This quasi-periodic multi-decadal temperature fluctuation persisted throughout the last millennium, and is likely to continue into the future.     

MARCO POLO: near earth object sample return mission

MARCO POLO is a joint European–Japanese sample return mission to a Near-Earth Object. This Euro-Asian mission will go to a primitive Near-Earth Object (NEO), which we anticipate will contain primitive materials without any known meteorite analogue, scientifically characterize it at multiple scales, and bring samples back to Earth for detailed scientific investigation. Small bodies, as primitive leftover building blocks of the Solar System formation process, offer important clues to the chemical mixture from which the planets formed some 4.6 billion years ago. Current exobiological scenarios for the origin of Life invoke an exogenous delivery of organic matter to the early Earth: it has been proposed that primitive bodies could have brought these complex organic molecules capable of triggering the pre-biotic synthesis of biochemical compounds. Moreover, collisions of NEOs with the Earth pose a finite hazard to life. For all these reasons, the exploration of such objects is particularly interesting and urgent. The scientific objectives of MARCO POLO will therefore contribute to a better understanding of the origin and evolution of the Solar System, the Earth, and possibly Life itself. Moreover, MARCO POLO provides important information on the volatile-rich (e.g. water) nature of primitive NEOs, which may be particularly important for future space resource utilization as well as providing critical information for the security of Earth. MARCO POLO is a proposal offering several options, leading to great flexibility in the actual implementation. The baseline mission scenario is based on a launch with a Soyuz-type launcher and consists of a Mother Spacecraft (MSC) carrying a possible Lander named SIFNOS, small hoppers, sampling devices, a re-entry capsule and scientific payloads. The MSC leaves Earth orbit, cruises toward the target with ion engines, rendezvous with the target, conducts a global characterization of the target to select a sampling site, and delivers small hoppers (MINERVA type, JAXA) and SIFNOS. The latter, if added, will perform a soft landing, anchor to the target surface, and make various in situ measurements of surface/subsurface materials near the sampling site. Two surface samples will be collected by the MSC using “touch and go” manoeuvres. Two complementary sample collection devices will be used in this phase: one developed by ESA and another provided by JAXA, mounted on a retractable extension arm. After the completion of the sampling and ascent of the MSC, the arm will be retracted to transfer the sample containers into the MSC. The MSC will then make its journey back to Earth and release the re-entry capsule into the Earth’s atmosphere.     

An interpretation of the decay characteristics of solar hard X-ray bursts

A simple trap model of solar hard X-ray bursts is discussed in which nonthermal electrons trapped in a magnetic bottle precipitate into the lower chromosphere through the resonant scattering by whistlers. In such a model, the X-ray spectra produced from trapped and precipitating electrons have different spectral shape, and both of the spectra will initially soften with time, provided the precipitation dominates over collisional degradation.     

On the Origin of S0 Stellar Populations

We investigate a one-zone chemo-photometric evolutionary model of truncated spiral galaxies with and without starbursts in order to explore the origin of the spectrophotometric properties of S0s. First, we show that 1) the tight U-V colour–magnitude (CM) relation cannot reject the model with a starburst and 2) the model with a starburst can explain the difference in the I-K colour–magnitude relation between S0 galaxies and spiral galaxies. Next, we demonstrate how we can distinguish the truncated spirals with a starburst from those without a starburst by using the CaII–Hδ/λ4045 diagram (proposed by Leonardi and Rose, 1996) and the 1550-V colour. This revised version was published online in July 2006 with corrections to the Cover Date.     

Study of metal contents of elasmobranch fishes: part 1—metal concentration in the muscle tissues of a dogfish, squalus mitsukurii

Concentrations of Hg, Zn, Fe, Cd and Cu in the muscle tissues of a dogfish, Squalus mitsukurii, were determined by atomic absorption spectrometry and found to be in the ranges of f0·019–2·13, 1·8–3·6, 1·5–5·7, 0·001–0·018 and 0·12–0·70 μg/g wet weight, respectively. The frequency distributions of concentrations, with the exception of mercury, were found to be log-normal. The correlation coefficient between mercury content and total length was positive and large and statistically highly significant. For other metals negative correlations were observed. Mercury concentration in the muscle was found to increase in proportion to the total length cubed. Regression of mercury concentration on age of sharks was shown to be linear. Analysis of covariance showed that the difference between sexes was not statistically significant, either in slope or in height. The concentration of mercury in the muscle tissues of embryos was considerably lower, Cd roughly the same and Zn and Fe higher than those of mothers. The concentrations of Zn, Fe and Cu are higher in the embryonic stage and immediately after birth than in later stages of growth.     

Attachment and feeding of pelagic copepods on larvacean houses

The attachment and feeding of pelagic copepods on discarded and occupied oikopleurid larvacean houses were investigated from May 1989 to August 1991 at an offshore station in the Nansei Islands, which is strongly influenced by the Kuroshio Current, and an inshore station in the central Seto Inland Sea.Oncaea spp.,Microsetella norvegica, and other calanoid and cyclopoid copepods were found attached onto discarded and occupied houses throughout the year at the offshore station, whereas neither discarded nor occupied houses, carried copepods at the inshore station at any time. The feeding behavior ofOncaea sp. in a discarded house was observed with a video tape recorder system.     

Mid-pacific mountains revisited

The Mid-Pacific Mountains are guyots whose volcanic pedestals have been constructed on a broad basement plateau, the flanks of which are downfaulted. Edifice construction may have been controlled by an orthogonal system of intersecting faults trending roughly ENE and NNW. Low amplitude gravity anomalies observed over the Mid-Pacific Mountains indicate complete Airy-Heiskanen isostatic compensation, crustal thickening, and eruption on thin elastic lithosphere. Tholeiites of the Mid-Pacific Mountains resemble lavas of Iceland and the Galapagos Islands. The orthogonal fault system, low gravity anomalies, and lava chemistry of the Mid-Pacific Mountains can be explained by eruption on or near a great ENE-trending rift system.     

Orbital signals found in physical and chemical properties of bottom sediments from Lake Baikal

Physical and chemical properties of two 100 m sediment cores (BDP-93-1, 93-2) obtained from the Buguldeika saddle of Lake Baikal in the eastern Siberia and a ¹⁴C-based age scale for the core show that the core bottom is about 400000 years ago and that the changes in the sedimentological environment of the area during the interval were that comparatively coarse and high C/N ratio sediments accumulated in the lake during interglacial periods, and fine material and low C/N ratio during glacial periods. The tentative age scale suggests that the first excursion in the earth's magnetic field at about 26 m (BDP-93-1 and 93-2) from the sediment surface corresponds to the Blake event. Statistical analyses of the data-sets for the some properties show that the fluctuations have distinct periods; 20000 years, 40000 years and 100000 years, that are related to the Milankovitch parameters and support that the tentative age scale is approximately acceptable.