Stellar 5 min oscillations

Estimates are given for the amplitudes of stochastically excited oscillations in Main Sequence stars and cool giants; these were obtained using the equipartition between convective and pulsational energy which was originally proposed by Goldreich and Keeley. The amplitudes of both velocity and luminosity perturbation generally increase with increasing mass along the Main Sequence as long as convection transports a major fraction of the total flux, and the amplitudes also increase with the age of the model. The 1.5 M _⊙ renceWorkEntry&sortOrder=relevance' class='reference-link webtrekk-track' gaCategory="Internal link" gaLabel="ZAMS" gaAction="reference keyword">ZAMS model, of spectral type F0, has velocity amplitudes ten times larger than those found in the Sun. For very luminous red supergiants luminosity amplitudes of up to about 0 ^m .1 are predicted, in rough agreement with observations presented by Maeder.     

Young massive star clusters in M51

A search for young massive star clusters (YMCs) in the nearby face-on spiral galaxy M51 (NGC 5194) has been carried out using UBV CCD images from the prime focus camera on the Lick 3-m Shane telescope. The YMC population is found to be quite rich with a specific U -band luminosity     consistent with the high current star formation rate (SFR) of this galaxy. The brightest clusters have     far brighter than any young clusters currently known in the Milky Way and even surpassing the luminosity of the R136 cluster in the 30 Dor complex in the Large Magellanic Cloud. A few of the YMCs are examined on archive images from the Wide Field Planetary Camera (WF/PC2) on board the Hubble Space Telescope ( HST ), confirming their cluster nature and providing estimates of their effective radii of 2–3 pc. The number of YMCs in M51 is compatible with extrapolation of a power-law luminosity function with exponent ∼−2 from a Milky Way-like population of open clusters. Both the SFR and T _L ( U ) of M51 are similar to those of other cluster-rich spiral galaxies like NGC 1313 and M83.     

亚硝酸根的动力学分析法进展

评述了动力学分析法测定亚硝酸根的发展状况,包括指示反应、线性范围、检测限和分析方法的应用,引用参考文献８１篇。     

Optical Changes in a Eutrophic Estuary During Reduced Nutrient Loadings

Loss of water clarity is one of the consequences of coastal eutrophication. Efforts have therefore been made to reduce external nutrient loadings of coastal waters. This paper documents improvements to water clarity between 1985 and 2008–2009 at four stations in the microtidal estuary Roskilde Fjord and find significant relationships to freshwater nutrient loadings. The paper then investigates to which extent changes in phytoplankton biomass (chlorophyll a (Chl a)), non-algal particulate organic matter (POM*), and residual attenuation in the water (K _b), respectively, can account for this optical improvement. Vertical light attenuation (K _d) declined, on average, by 34 %, accompanying a 71 % reduction of Chl a and an 80 % reduction of POM*. Residual attenuation declined by 26 % over the period in accordance with a measured 34 % decline of dissolved organic nitrogen. Analysis of simultaneous changes in light attenuation and Secchi depth also suggested a reduction of the scatter-to-absorption ratio over time. Considering the stronger reductions of particle concentrations than dissolved organic matter, the contribution of residual attenuation to vertical attenuation increased from 54 to 74 % in 1985 to 78 to 85 % in 2008–2009. Overall, efforts to reduce nutrient loading and improve water clarity appeared to have had a larger impact on POM* than on Chl a and colored dissolved organic matter concentrations in the estuary, which can account for the decrease in the scatter-to-absorption ratio. These optical changes lead to larger improvements of Secchi depth than of vertical light attenuation. The consequence of this is an overestimation (0.45–1.48 m) of the predicted increase of potential seagrass depth limits when based on Secchi depth rather than K _d.     

GCF系列冲击反循环工程钻机的研制

介绍了GCF系列冲击反循环工程钻机的研制概况以及主要技术参数、性能特点、生产试验情况等。     

中国东南大陆中生代火山岩带研究进展和方向

总结了目前东南大陆中生代火山岩带研究的主要成果、存在问题及其基本原因 ,提出了今后应进一步研究的方向 ,并且指出新一轮国土资源大调查为深化前人成果、把该火山岩带的研究水平提高到新的阶段提供了难得的机遇。     

The internal structure of the Arosa Zone (Swiss-Austrian Alps)

The Arosa Zone, part of the main Alpine suture zone between the Austroalpine and the Penninic realms, forms a heterogeneous unit composed of rocks of oceanic and continental origin. It exhibits mélange character due to minor sedimentary mixing and local penetrative tectonic deformation during Cretaceous and Early Tertiary imbrication. Competent blocks of both Austroalpine and Penninic origin, covering up to 2.5 km², are embedded in incompetent serpentinitic or shaly-calcareous matrix. On a mesoscale, disrupted strata occur in and adjacent to thrust and shear zones. Contrasting competence between blocks and matrix partitioned deformation into brittle and ductile processes. Extension veins and shear fractures affected the competent strata whereas the matrix developed a penetrative foliation during ductile flow and accommodated high strain. Flow was mainly non-coaxial in the matrix, and coaxial extension prevailed in the blocks.In a regional tectonic setting, we define the Arosa Zone as the tectonostratigraphic unit sandwiched between the Austroalpine and Penninic units. It forms a narrow and highly imbricated zone containing both South Penninic ophiolitic and sedimentary rocks as well as blocks and slices of Austroalpine origin.

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Zusammenfassung Die Arosa Zone ist Teil der Alpinen Suturzone zwischen Ostalpin und Pennimkum und bildet eine lithologisch heterogene Einheit aus kontinentalen und ozeanischen Gesteinen. Sie zeigt den Charakter einer Melange, die aus, untergeordnet, sedimentärer Durchmischung und lokaler, aber penetrativer tektonischer Deformation während kretazisch und alttertiärer Tektonik resultiert. Kompetente Blöcke ostalpiner und penninischer Herkunft, die bis zu 3 km im Streichen verfolgbar sind, schwimmen in einer inkompetenten serpentinitischen oder tonig-karbonatischen Matrix. Im Mesobereich treten zerbrochene Gesteinsabfolgen in oder direkt an Überschiebungs- und Scherzonen auf. Unterschiedliche Kompetenz zwischen Blöcken und Matrix teilt die Deformation in spröde und duktile Prozesse auf. Die kompetenten Gesteine zeigen Extensionsspalten und Scherbrüche, in der Matrix entwickelte sich durch duktiles Fließen eine penetrative Schieferung bei hoher Strainintensität. Die Deformation in der Matrix war hauptsächlich nicht-koaxial, koaxiale Extension herrschte in den Blöcken.Im regionalen tektonischen Rahmen definieren wir die Arosa Zone als tektonostratigraphische Einheit zwischen Ostalpin und Penninikum. Sie bildet eine schmale, stark imbrikierte Zone die, aus südpenninischen ophiolithischen und sedimentären Gesteinen, sowie aus Blöcken und Spänen ostalpiner Herkunft aufgebaut wird.

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Résumé La Zone d'Arosa, partie de la zone de suture alpine entre l'Austro-alpin et le Pennique, forme une unité hétérogène composée de roches d'origines océanique et continentale. Elle présente le caractère d'un mélange qui résulte d'un brassage sédimentaire mineur, et de déformations tectoniques, locales mais pénétratives, au cours du Crétacé et du Tertiaire ancien. Des blocs compétents de l'Austro-alpin et du Pennique qui couvrent jusqu'à 2.5 km², sont enrobés dans une matrice incompétente serpentineuse ou argilo-calcaire. A moyenne échelle, les couches disloquées se rencontrent dans les zones charriées et cisaillées, ou y sont adjacentes. La différence de compétence entre les blocs et la matrice répartit la déformation en processus cassants et ductiles. Les roches compétentes montrent des fentes d'extension et des fractures de cisaillement, alors que dans la matrice, sous l'action d'un flux ductile et d'une intensité de contrainte élevée, se développe une foliation pénétrative. La déformation fut principalement non coaxiale dans la matrice et coaxiale dans les blocs d'extension.Dans un cadre tectonique régional, nous définissons la Zone d'Arosa comme une unité tectonostratigraphique prise entre l'Austro-alpin et le Pennique. Elle constitue une zone étroite et fortement imbriquée composée aussi bien de roches ophiolitiques du Sud-Pennique et de roches sédimentaires, que de blocs et d'écaillés de l'Austro-alpin.

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Impact of isostatic land uplift and artificial drainage on oxidation of brackish-water sediments rich in metastable iron sulfide

This study examines the dynamics of sulfur and trace elements (As, Co, Mo, Ni, Ti and Zn) when brackish-water sediments, unusually rich in metastable iron sulfide (probably a mixture of mackinawite and greigite), are brought into the oxidation zone by postglacial isostatic land uplift and farmland drainage. When subaqueous sediments approach the sea level, metastable iron sulfide is oxidized in the upmost layers and pyrite preserved and even accumulated concomitantly trapping Co, Ni and Zn but not As and Mo. When the land uplift has brought the sediments above sea level and natural drainage thus is initiated, the pyrite is oxidized and Co, Ni and Zn are released and transported down the profile. If this setting remained undisturbed, the slightly oxidized sediment (unripe soil) would become covered by peat and thus protected from further oxidation and metal translocation. Often these sediments are, however, artificially drained resulting in extensive oxidation and fast soil-profile development. The soil is an acid sulfate (AS) soil, characterized by low pH (<4), extensive leaching of metals and an abundance of disseminated brownish Fe(III) precipitates. We suggest that the fast soil development is due to initial oxidation of metastable iron sulfide, followed by pyrite oxidation. Drain bottom sediment, which in terms of chemistry and S-isotopes resembled that of the surfacing sea bottom strata, acted during the sampling period as a sink for metals. The abundant preservation of metastable iron sulfide below the groundwater table, even long periods after uplift above the sea level, is a puzzling feature. We suggest that it is the net result of sulfur starvation, an abundance of Fe(II) and strongly reducing conditions.     

桐柏-大别造山带高压变质单元面理化(含榴)花岗岩地球化学及其对岩石成因的限制

桐柏-大别造山带中,面理化(含榴)花岗岩作为榴辉岩的重要围岩之一,仅分布在高压变质单元和超高压变质单元中.对高压变质单元中面理化(含榴)花岗岩进行了元素地球化学研究,结果显示,这类岩石 SiO2 71.96%～ 77.99%, K2O Na2O 7.59%～8.66%, Al2O3 11.15%～14.50%, CaO 0.10%～0.91%, MgO0.04%～0.73%,Sr 27.3～269 μ g/g,A/CNK 0.97～1.10.相对于 S型和 I型花岗岩,面理化(含榴)花岗岩具有某些 A型花岗岩的地球化学特征,如岩石明显富硅、富碱质和富高场强元素(如 Zr、Hf、Nb、Ta、Y等),贫 Ca、Mg、Al、Sr等元素,高 Ga/Al比值;在稀土元素特征方面,大部分样品具有明显的 Eu负异常(Eu/Eu0.06～0.60),(La/Yb)N 2.34～7.87.在岩石成因类型元素判别图解上,面理化(含榴)花岗岩主要落于 A型花岗岩区;构造判别图解和构造学、岩石学特征表明该类花岗岩形成于碰撞后的构造环境.因此,高压变质单元面理化(含榴)花岗岩总体地球化学特征表明它们属于 A型花岗岩类,形成于岩石圈伸展的碰撞后构造环境,与大别山超高压 /高压变质岩的折返过程存在密切联系.     

Possible mode conversion between Love and Rayleigh waves at a continental margin

Summary. Mode conversion at a continental margin between normal modes of surface waves is investigated by theoretical calculations for oblique incidence for periods longer than 15 s. It is suggested that significant conversion takes place between the various modes of Love waves in the period interval between 15 and 40 s, while there is negligible mode conversion for longer periods. The largest mode conversion involves the lowest modes. In addition the calculations have revealed a small but significant conversion between Love and Rayleigh fundamental modes around 20-s period. Reflections of Love waves are found to be significant only for the continental fundamental mode.