A luminescence‐based chronology for the Harletz loess sequence,Bulgaria

The Harletz loess‐palaeosol sequence is located in northwestern Bulgaria and represents an important link between well‐studied loess sequences in eastern Romania and further sites to the west of the Carpathians (e.g. Serbia and Hungary). The aim of this study was to establish a chronostratigraphy of the deposits, using various methods of luminescence dating, together with basic stratigraphical field observations as well as magnetic properties. Luminescence dating was carried out using the quartz fine grain fraction and a SAR protocol, and the feldspar coarse grain fraction, applying the MET‐pIRIR protocol. Due to underestimation of the quartz fine grain fraction in the lower parts of the sequence, the resulting chronology is mainly based on the feldspar ages, which are derived from the stimulation temperature at 150 °C. A comparison with nearby sequences from Serbia, Hungary and Romania, and interpretations obtained through the stratigraphical and sedimentological signature of the sequence, supports the established chronology. Our data suggest that the prominent palaeosol (soil complex) in the upper quarter of the sequence was formed during MIS 5. It would follow that large parts of the Last Glacial loess overlying this palaeosol were probably eroded, and that the thick loess accumulation underlying this soil complex can be allocated to the penultimate glacial (MIS 6). A prominent MIS 6 tephra, which has been reported from other sequences in the area, is also present at Harletz.     

Synthetic stellar and SSP libraries as templates for Gaia simulations

ESA’s Gaia mission will collect low resolution spectroscopy in the optical range for ～10⁹ objects. Complete and up-to-date libraries of synthetic stellar spectra are needed to built algorithms aimed to automatically derive the classification and the parametrization of this huge amount of data. In addition, libraries of stellar spectra are one of the main ingredients of stellar population synthesis models, aiming to derive the properties of unresolved stellar populations from their integrated light. We present (a) the newly computed libraries of synthetic spectra built by the Gaia community, covering the whole optical range (300–1100 nm) at medium-high resolution of (0.3 nm) for stars spanning the most different types, from M to O, from A-peculiar to Emission lines to White Dwarfs, and (b) the implementation of those libraries in our SSP code (Tantalo in The Initial Mass Function 50 Years Later, 327:235 2005), exploring different stellar evolution models.     

A photohabitable zone in the martian snowpack? A laboratory and radiative-transfer study of dusty water-ice snow

Dusty water-ice snowpacks on Mars may provide a habitable zone for DNA based photosynthetic life. Previous work has over estimated the depths and thicknesses of such photohabitable zones by not considering the effect of red dust within the snowpack. For the summer solar solstice, at 80°N and a surface albedo of 0.45, there is a calculated photohabitable zone in the snowpack between depths of 5.5 and 7.5 cm. For an albedo of 0.62, there is a calculated photohabitable zone in the snowpack between depths of 8 and 11 cm. A coupled atmosphere-snow radiative-transfer model was set to model the Photosynthetic Active Radiation and DNA dose rates through water-ice snow at the north polar region of Mars. The optical properties of the polar caps were determined by creating a laboratory analogue to the Mars north polar deposits, and directly measuring light penetration and albedo. It is important for future exobiology missions to the polar regions of Mars to consider the implications of these findings, as drilling to depths of ∼11 cm should be sufficient to determine whether life exists within the martian snows, whether it is photosynthetic or otherwise, as at this depth the snow cover will provide a permanent protection from DNA damaging UV radiation.     

Modelling grazed grassland systems: wether sheep grazing perennial ryegrass

A simple model or a lowland sheep flock grazing a ryegrass sward is described, which incorporates herbage growth and deterioration; the mechanics of grazing, herbage intake and animal production. The model takes into account the effects of climate, the availability of water and nitrogen and the frequency and intensity of defoliation on herbage production; diet selection by the grazing animal; the effects of herbage digestibility and animal body weight on intake; and the fate of the organic matter ingested by the ruminant. Preliminary results comparing continuous and rotational grazing systems and different levels of nitrogen fertilizer application are discussed. Some possible areas for further applied research are also outlined.     

Surge tank water level variations following rapid valve opening

An investigation into the movement of the water surface in a surge tank following rapid valve opening is described. At the instant the valve is opened an allowance is made for some flow from the supply pipeline in addition to that from the surge tank and therefore the theory is altered only in the initial conditions. A program was written for a small desk-top calculator linked to a graph plotter to give a visual presentation of the finite difference solutions. Comparison was made with experimental values of the maximum downsurge observed in a model surge tank.     

华南、华北地块中生代构造演化与超高压变质岩的折返机制

本文在讨论中国东部现有构造演化模式基础上，着重从华北与华南地块之间板块尺度的动力学过程剖析秦岭－大别中生代造山带构造演化，以及大别－苏鲁超高压变质地体的形成和折返过程。晚二叠世－中三叠世华南地块向华北地块持续挤压，陆壳大规模俯冲导致超高压变质作用的产生，而华北地块在晚三叠世至早侏罗世发生快速逆时针旋转，使得这一地区上地幔深度的超高压变质地体快速折返至下地壳。由于超高压变质地体侵位后，地壳结构、构造的差异，在南北地块的进一步挤压下，造成中国东部晚侏罗世－早白垩世郯庐断裂带的巨大左行剪切。     

The Cosmic Origins Spectrograph: on-orbit instrument performance

The Cosmic Origins Spectrograph (COS) was installed in the Hubble Space Telescope in May, 2009 as part of Servicing Mission 4 to provide high sensitivity, medium and low resolution spectroscopy at far- and near-ultraviolet wavelengths (FUV, NUV). COS is the most sensitive FUV/NUV spectrograph flown to date, spanning the wavelength range from 900 Å to 3200 Å with peak effective area approaching 3000 cm². This paper describes instrument design, the results of the Servicing Mission Orbital Verification (SMOV), and the ongoing performance monitoring program.