Material screening and selection for XENON100

Results of the extensive radioactivity screening campaign to identify materials for the construction of XENON100 are reported. This dark matter search experiment is operated underground at Laboratori Nazionali del Gran Sasso (LNGS), Italy. Several ultra sensitive High Purity Germanium detectors (HPGe) have been used for gamma ray spectrometry. Mass spectrometry has been applied for a few low mass plastic samples. Detailed tables with the radioactive contaminations of all screened samples are presented, together with the implications for XENON100.     

The Bar and Spiral Structure Legacy (BeSSeL) survey: Mapping the Milky Way with VLBI astrometry

Astrometric Very Long Baseline Interferometry (VLBI) observations of maser sources in the Milky Way are used to map the spiral structure of our galaxy and to determine fundamental parameters such as the rotation velocity (Θ₀) and curve and the distance to the Galactic center (R₀). Here, we present an update on our first results, implementing a recent change in the knowledge about the Solar motion. It seems unavoidable that the IAU recommended values for R₀ and Θ₀ need a substantial revision. In particular the combination of 8.5 kpc and 220 km s^–1 can be ruled out with high confidence. Combining the maser data with the distance to the Galactic center from stellar orbits and the proper motion of Sgr A* gives best values of R₀ = 8.3 ± 0.23 kpc and Θ₀ = 239 or 246±7 km s^–1, for Solar motions of V_⊙ = 12.23 and 5.25 km s^–1, respectively. Finally, we give an outlook to future observations in the Bar and Spiral Structure Legacy (BeSSeL) survey (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Buoyant boundary layer flows- an analogy to the Ekman spiral

Abstract

Flow details inside the buoyant boundary layer in the heat-up process of a contained, stably stratified, fluid are presented. Numerical solutions were obtained for the heatup problem in a cylinder considered by Sakurai and Matsuda (1972). By plotting the scaled vertical velocity W versus the scaled temperature θ as functions of the normal distance from the sidewall, the precise shape of the buoyant layer spiral is constructed. The analogy between this spiral and the Ekman spiral in rotating fluids is apparent. As the Rayleigh number Ra increases, the magnitude of the scaled vertical velocity increases substantially, but the scaled temperature does not vary appreciably. The buoyant layer thickness is determined by measuring the zero-crossing normal distance for the vertical velocity. The buoyant layer suction increases significantly as Ra increases. The effects of vertical level and of time on the qualitative behavior of buoyant layer flows are found to be small. The buoyant layer flows decay over the heat-up time scale t _n ; t _h characterizes the time span over which the overall adjustment process in the inviscid interior region is accomplished. This work clarifies that the analogy between heat-up and spin-up, which has been known to exist in the main body of inviscid fluid, applies equally well to the boundary layer regions.     

U–Pb SHRIMP zircon geochronology,petrogenesis, and tectonic setting of the Neoproterozoic Baekdong ultramafic rocks in the Hongseong Collision Belt,South Korea

The Hongseong area, located in the western Gyeonggi Massif, South Korea, can be correlated with the northern margin of the South China block (Yangtze Craton). This area experienced Neoproterozoic igneous activity related to subduction before the amalgamation of Rodinia. Several isolated, lenticular, and serpentinized ultramafic–mafic bodies occur in the Hongseong area. The Baekdong body, one of the largest ultramafic bodies, has been highly deformed and metamorphosed to eclogite- and granulite-facies. The petrogenesis and tectonic environment of the Baekdong rocks are assessed using the composition of unaltered cores of spinel and olivine grains, and show that these rocks represent the mantle section of a suprasubduction ophiolite. The rocks originated from oceanic lithosphere that formed during the transition from nascent back-arc to mature island arc, related to subduction roll-back. During the back-arc stage, Al-rich spinel harzburgite formed through melt–rock interaction caused by the intrusion of magma. This magma was produced in small amounts, by less than 10% of partial melting of the wedge mantle. Subsequently, during the mature island arc stage, Cr-rich spinel dunite formed through melt–rock interaction caused by the intrusion of relatively evolved magma that formed by 30–35% partial melting due to a high input of volatiles from the subducted slab and sediments. The Baekdong ultramafic rocks, together with the Bibong ultramafic rocks, indicate that a suprasubduction tectonic setting prevailed before the amalgamation of Rodinia (at 860–890 Ma) in the Hongseong area, which may be an extension of the northern margin of the Yangtze Craton.     

Tintinnid species as biological indicators for monitoring intrusion of the warm oceanic waters into Korean coastal waters

This study examined seasonal and annual occurrences of warm oceanic tintinnid species in southern Korea coastal waters. The indicative species of tintinnids was monitored using three approaches: monitoring from cruises traveling from the warm pool in the western North Pacific to the Korea Strait; biweekly or monthly monitoring in the Korea Strait; and daily monitoring in the nearshore water. Annual pulses of warm oceanic indicator species were regularly observed in the Korea Strait. In September 2008 recorded a maximum species number of warm water indicators, a representative species for warm oceanic waters, Climacocylis scalaroides was simultaneously detected in the nearshore water as well as the Korea Strait. The result indicates that the greater warm water extension into Korean coastal areas was in September 2008. Sharp declines in species diversity were observed in the transitional area between neritic and Kuroshio zone in East China Sea (ECS). Epiplocyloides reticulata, reported previously as a Kuroshio indicator, was considered an ECS indicator species, as it was undetected in the western North Pacific central zone but was found abundantly in the ECS. Tintinnid species can be used as biological indicators to detect the inflow of warm oceanic waters into Korean coastal waters.     

Assessment of immune parameters of manila clam <Emphasis Type="Italic">Ruditapes philippinarum</Emphasis> in different physiological conditions using flow cytometry

Cellular and humoral immune parameters are often used as biomarkers to trace environmental and physiological stresses in marine bivalves. In this study, we compared various immune parameters of Manila clams (Ruditapes philippinarum) under normal conditions and under a high level of desiccation, using flow cytometry. The immune parameters analyzed included, total hemocyte count, hemocyte mortality, hemocyte DNA damage, reactive oxygen species (ROS) production, and phagocytosis activity. Total hemocyte count, hemocyte DNA damage, and hemocyte mortality were significantly elevated among clams under high desiccation stress, while phagocytosis activity and spontaneous ROS production were significantly lower compared to those parameters of the control clams (p<0.05). These data suggest that the immune parameters analyzed in this study well reflect the physiological status of clams.     

Search for spatial and spectral fluctuations of cosmic microwave background radiation with the ratan-600 radio telescope. The 2001–2006 observations

We report some of the results of the search for narrow-band spatial and spectral fluctuations of cosmic microwave background at the wavelength of 6.2 cmperformed with the RATAN-600 radio telescope in 2001–2006 in two 35′ × 7′ strips on the sky in the vicinity of the North Celestial Pole. We find the spectra of spatial fluctuations in the 12 MHz radio-frequency band and in the interval of spatial periods from 4′ to 16′ to exhibit power-law rises with exponents reaching ?2.0±0.5, with a periodicity of 2–3 MHz. We also find two narrow-band (in terms of angular frequency) features at 4870.4 and 4871.5 MHz with the corresponding fluctuation amplitudes of 5±0.5 mK in terms of antenna temperature in the vicinity of angular periods of about 5′ with the frequency bandwidths of about 600 kHz. Standard tests performed using the spectra of the half-sum and half-difference of two groups of observations randomly drawn from a total sample of 23 records of the March 2002 observing set confirm the reality of the features of the angular spectrumof fluctuations mentioned above and so does the comparison with the spectra of cold matched load connected to the receiver input instead of the antenna. However, the nature of the features found remains unclear. Our attempt to link this radiation to rotational transitions ²Π_1/2, J = 5/2 of the CH molecule, which has one of the components of its multiplet located inside the frequency interval of interest considered failed.     

Spatial and seasonal variations in the water quality of Jinhae Bay,Korea

The chemical and biological characteristics of surface waters in Jinhae Bay were investigated over four seasons to understand water quality in light of the growing industrialisation occurring within this area. Jinhae Bay includes four smaller bays: Masan; Hangam; Jindong; and Gohyun. The water quality in Jinhae Bay varied spatially and seasonally. The water quality of both Hangam Bay and Masan Bay was highly degraded, demonstrating high concentrations of ammonia, nitrate, chlorophyll a and particulate organic carbon. Contamination from sewage was the dominant cause of the water quality deterioration in these bays. Conversely, the water quality in Jindong Bay and Gohyun Bay was not as severely affected as that of the above two bays. Water quality in Jinhae Bay was particularly poor in summer when nutrient loading was highest due to the run-off associated with high precipitation. Principal component analysis indicated that nitrogen contamination was a major factor influencing the water quality of Jinhae Bay. The effective reduction in high-nitrogen discharges is essential to improve water quality in Jinghae Bay.