The population of pulsars with interpulses and the implications for beam evolution

The observed fraction of pulsars with interpulses, their period distribution and the observed pulse width versus pulse period correlation are shown to be inconsistent with a model in which the angle α between the magnetic axis and the rotation axis is random. This conclusion appears to be unavoidable, even when non-circular beams are considered. Allowing the magnetic axis to align from a random distribution at birth with a time-scale of  ∼7 × 10⁷ yr  can, however, explain those observations well. The time-scale derived is consistent with that obtained via independent methods. The probability that a pulsar beam intersects the line of sight is a function of the angle α and therefore beam evolution has important consequences for evolutionary models and for estimations of the total number of neutron stars. The validity of the standard formula for the spin-down rate, which is independent of α, appears to be questionable.     

Growth Rates of Global Energy Systems and Future Outlooks

The world is interconnected and powered by a number of global energy systems using fossil, nuclear, or renewable energy. This study reviews historical time series of energy production and growth for various energy sources. It compiles a theoretical and empirical foundation for understanding the behaviour underlying global energy systems’ growth. The most extreme growth rates are found in fossil fuels. The presence of scaling behaviour, i.e. proportionality between growth rate and size, is established. The findings are used to investigate the consistency of several long-range scenarios expecting rapid growth for future energy systems. The validity of such projections is questioned, based on past experience. Finally, it is found that even if new energy systems undergo a rapid ‘oil boom’-development—i.e. they mimic the most extreme historical events—their contribution to global energy supply by 2050 will be marginal.     

Estimation of surface latent heat fluxes from IRS-P4/MSMR satellite data

The brightness temperatures of the Microwave sensor MSMR (Multichannel Scanning Microwave Radiometer) launched in May 1999 onboard Indian Oceansat-1 IRS-P4 are used to develop a direct retrieval method for latent heat flux by multivariate regression technique. The MSMR measures the microwave radiances at 8 channels at frequencies of 6.6, 10.7, 18 and 21 GHz at both vertical and horizontal polarizations. It is found that the surface LHF (Latent Heat Flux) is sensitive to all the channels. The coefficients were derived using the National Centre for Environmental Prediction (NCEP) reanalysis data of three months: July, September, November of 1999. The NCEP daily analyzed latent heat fluxes and brightness temperatures observed by MSMR were used to derive the coefficients. Validity of the derived coefficients was checked within situ observations over the Indian Ocean and with NCEP analyzed LHF for global points. The LHF derived directly from the MSMR brightness temperature (Tb) yielded an accuracy of 35 watt/m². LHF was also computed by applying bulk formula using the geophysical parameters extracted from MSMR. In this case the errors were higher apparently due to the errors involved in derivation of the geophysical parameters.     

Saqqar: A 34 km diameter impact structure in Saudi Arabia

Here we present the first proof of an impact origin for the Saqqar circular structure in northwestern Saudi Arabia (Neville et al. 2014 ), with an apparent diameter of 34 km, centered at 29°35′N, 38°42′E. The structure is formed in Cambrian–Devonian siliciclastics and is unconformably overlain by undeformed Cretaceous and Paleogene sediments. The age of impact is not well constrained and lies somewhere between 410 and 70 Ma. The subsurface structure is constrained by 2‐D reflection seismic profiles and six drilled wells. First‐order structural features are a central uplift that rises approximately 2 km above regional datums, surrounded by a ring syncline. The crater rim is defined by circumferential normal faults. The central uplift and ring syncline correspond to a Bouguer gravity high and an annular ring‐like low, respectively. The wells were drilled within the central uplift, the deepest among them exceed 2 km depth. Sandstone core samples from these wells show abundant indicators of a shock metamorphic overprint. Planar deformation features (PDFs) were measured with orientations along (0001), {103}, and less frequently along {101} and {104}. Planar fractures (PFs) predominantly occur along (0001) and {101}, and are locally associated with feather features (FFs). In addition, some shocked feldspar grains and strongly deformed mica flakes were found. The recorded shock pressure ranges between 5 and 15 GPa. The preserved level of shock and the absence of an allochthonous crater fill suggest that Saqqar was eroded by 1–2 km between the Devonian and Maastrichtian. The documentation of unequivocal shock features proves the formation of the Saqqar structure by a hypervelocity impact event.     

Solar flux determination in the spectral range 150–210 nm

Solar irradiation fluxes are determined between 150 and 210 nm from stigmatic spectra of the Sun obtained by means of a rocket-borne spectrograph. Absolute intensities at the disk center with a spectral resolution of 0.04 nm and a spatial resolution of 7 arc sec are presented. From center-to-limb intensity variations determined from the same spectra, mean full disk intensities of the quiet Sun can be deduced. In order to compare them with other measurements, the new solar fluxes have been averaged over a bandpass of 1 nm.     

Composition of jovian dust stream particles

The Cassini spacecraft encountered Jupiter in late 2000. Within more than 1 AU of the gas giant the Cosmic Dust Analyser onboard the spacecraft recorded the first ever mass spectra of jovian stream particles. To determine the chemical composition of particles, a comprehensive statistical analysis of the dataset was performed. Our results imply that the vast majority (>95%) of the observed stream particles originate from the volcanic active jovian satellite Io from where they are sprinkled out far into the Solar System. Sodium chloride (NaCl) was identified as the major particle constituent, accompanied by sulphurous as well as potassium bearing components. This is in contrast to observations of gas in the ionian atmosphere, its co-rotating plasma torus, and the neutral cloud, where sulphur species are dominant while alkali and chlorine species are only minor components. Io has the largest active volcanoes of the Solar System with plumes reaching heights of more than 400 km above the moons surface. Our in situ measurements indicate that alkaline salt condensation of volcanic gases inside those plumes could be the dominant formation process for particles reaching the ionian exosphere.     

Distinguishing extensive and intensive properties for meaningful geocomputation and mapping

A most fundamental and far-reaching trait of geographic information is the distinction between extensive and intensive properties. In common understanding, originating in Physics and Chemistry, extensive properties increase with the size of their supporting objects, while intensive properties are independent of this size. It has long been recognized that the decision whether analytical and cartographic measures can be meaningfully applied depends on whether an attribute is considered intensive or extensive. For example, the choice of a map type as well as the application of basic geocomputational operations, such as spatial intersections, aggregations or algebraic operations such as sums and weighted averages, strongly depend on this semantic distinction. So far, however, the distinction can only be drawn in the head of an analyst. We still lack practical ways of automation for composing GIS workflows and to scale up mapping and geocomputation over many data sources, e.g. in statistical portals. In this article, we test a machine-learning model that is capable of labeling extensive/intensive region attributes with high accuracy based on simple characteristics extractable from geodata files. Furthermore, we propose an ontology pattern that captures central applicability constraints for automating data conversion and mapping using Semantic Web technology.     

Gold partitioning in melt-vapor-brine systems

We used laser-ablation inductively coupled plasma mass spectrometry to measure the solubility of gold in synthetic sulfur-free vapor and brine fluid inclusions in a vapor + brine + haplogranite + magnetite + gold metal assemblage. Experiments were conducted at 800°C, oxygen fugacity buffered at Ni-NiO (NNO), and pressures ranging from 110 to 145 MPa. The wt% NaCl eq. of vapor increases from 2.3 to 19 and that of brine decreases from 57 to 35 with increasing pressure. The composition of the vapors and brines are dominated by NaCl + KCl + FeCl₂ + H₂O. Gold concentrations in vapor and brine decrease from 36 to 5 and 50 to 28 μg/g, respectively, and the calculated vapor:brine partition coefficients for gold decrease from 0.72 to 0.17 as pressure decreases from 145 to 110 MPa. These data are consistent with the thermodynamic boundary condition that the concentration of gold in the vapor and brine must approach a common value as the critical pressure is approached along the 800°C isotherm in the NaCl-KCl-FeCl₂-HCl-H₂O system.We use the equilibrium constant for gold dissolution as AuOH⁰, extrapolated from lower temperature and overlapping pressure range, to calculate expected concentrations of AuOH⁰ in our experimental vapors. These calculations suggest that a significant quantity of gold in our experimental vapors is present as a non-hydroxide species. Possible chloridogold(I) species are hypothesized based on the positively correlated gold and chloride concentrations in our experimental vapors. The absolute concentration of gold in our synthetic vapor, brine, and melt and calculated mass partition coefficients for gold between these physicochemically distinct magmatic phases suggests that gold solubility in aqueous fluids is a function of aqueous phase salinity, specifically total chloride concentration, at magmatic conditions. However, though we highlight here the effect of salinity, the combination of our data with data sets from lower temperatures evinces a significant decrease in gold solubility as temperature drops from 800°C to 600°C. This decrease in solubility has implications for gold deposition from ascending magmatic fluids.     

基于GPlates平台的“深时”板块构造重建：数据库现状与应用实例

板块构造重建是大地构造领域一项关键的研究工作,是构建"深时数字地球"(Deep-time Digital Earth, DDE)的重要途径。板块重建工作需要整合地球科学多个研究领域、海量的数据,同时又是地球动力学和气候模拟等研究的重要约束条件。因此,追踪目前国际主流的板块重建所需的数据库以及板块重建工具的最新进展和应用为了解板块重建研究的前沿提供全面的信息。文章系统介绍了支持板块构造重建研究的多个主流数据库,着重描述数据库的数据格式、数据获取方式及数据如何支持基于GPlates平台的板块构造重建。为了阐述大地构造研究相关数据库在板块重建研究中的应用,此次研究从板块构造重建的三个不同层次出发,列举了多个最新的板块重建模型及其在探索地球系统演化方面的意义。最后,结合DDE项目的相关任务,对250 Ma以来全球板块构造和变形的演化、量化大地构造在地球系统演化中的作用、超大陆旋回中的古大陆和古海洋构造重建以及前中生代(250 Ma)全球板块运动模型重建这四个关键科学问题作出了新的展望。