The CM carbonaceous chondrite regolith Diepenveen

A carbonaceous chondrite was recovered immediately after the fall near the village of Diepenveen in the Netherlands on October 27, 1873, but came to light only in 2012. Analysis of sodium and poly‐aromatic hydrocarbon content suggests little contamination from handling. Diepenveen is a regolith breccia with an overall petrology consistent with a CM classification. Unlike most other CM chondrites, the bulk oxygen isotopes are extremely ¹⁶O rich, apparently dominated by the signature of anhydrous minerals, distributed on a steep slope pointing to the domain of intrinsic CM water. A small subset plots closer to the normal CM regime, on a parallel line 2 ‰ lower in δ¹⁷O. Different lithologies in Diepenveen experienced varying levels of aqueous alteration processing, being less aqueously altered at places rather than more heated. The presence of an agglutinate grain and the properties of methanol‐soluble organic compounds point to active impact processing of some of the clasts. Diepenveen belongs to a CM clan with ~5 Ma CRE age, longer than most other CM chondrites, and has a relatively young K‐Ar resetting age of ~1.5 Ga. As a CM chondrite, Diepenveen may be representative of samples soon to be returned from the surface of asteroid (162173) Ryugu by the Hayabusa2 spacecraft.     

Identifying scale-location specific control on vegetation distribution in mountain-hill region

The scale-location specific control on vegetation distribution was investigated through continuous wavelet transforms approaches in subtropical mountain-hill region, Fujian, China. The Normalized Difference Vegetation Index (NDVI) was calculated as an indicator of vegetation greenness using Chinese Environmental Disaster Reduction Satellite images along latitudinal and longitudinal transects. Four scales of variations were identified from the local wavelet spectrum of NDVI, with much stronger wavelet variances observed at larger scales. The characteristic scale of vegetation distribution within mountainous and hilly regions in Southeast China was around 20 km. Significantly strong wavelet coherency was generally examined in regions with very diverse topography, typically characterized as small mountains and hills fractured by rivers and residents. The continuous wavelet based approaches provided valuable insight on the hierarchical structure and its corresponding characteristic scales of ecosystems, which might be applied in defining proper levels in multilevel models and optimal bandwidths in Geographically Weighted Regression.     

On the Fluxes of Dust Particles Detected near the Lunar Surface by the Chang’e 3 Lander

Solar System Research - We analyze the origin of dust particles in the near-surface layer of the Moon, the fluxes of which were measured in the Chang’e 3 lunar mission carried out by the...     

The chemical durability of tektites—A laboratory study and correlation with long-term corrosion behavior

Leach tests carried out on tektite specimens (indochinites and australites) under high-dilution conditions show a common behavior characterized by low leach rates (1.8 × 10^?5g · m^?2 · d^?1or 7.2 × 10^?12m · d^?1 at 23°C) and an activation energy of (79.6 ± 0.7) × 10³J · mol^?1. The extent of selective leaching is very small, of the order of 10^?8 m. Extrapolation of test results over the lifetime of the tektites gives an excellent agreement with field observations on the extent of corrosion, and this is an important step in establishing the validity of laboratory tests as a basis for the development of models and predictions concerning long-term durabilities at least in the limiting case of high dilution or rapid flow. The results are also shown to be in agreement with various previous observations on the corrosion resistance of tektites. The chemical durability of tektites is observed to be consistent with their composition, highlighting requirements for high corrosion resistance in glasses; these requirements include a silica content in excess of 67 mol%, an extremely low water content and an alkali content which is low both absolutely and relative to the di- and poly-valent metal oxide levels. It is shown that artificial glasses which fulfil these criteria are no less corrosion-resistant than the corresponding natural glasses. These conclusions have bearing on the development as well as on the evaluation of glasses intended for very long service, such as radioactive waste vitrification media.     

Analysis of Magnetic Shear in An X17 Solar Flare on October 28, 2003

An X17 class (GOES soft X-ray) two-ribbon solar flare on October 28, 2003 is analyzed in order to determine the relationship between the timing of the impulsive phase of the flare and the magnetic shear change in the flaring region. EUV observations made by the Transition Region and Coronal Explorer (TRACE) show a clear decrease in the shear of the flare footpoints during the flare. The shear change stopped in the middle of the impulsive phase. The observations are interpreted in terms of the splitting of the sheared envelope field of the greatly sheared core rope during the early phase of the flare. We have also investigated the temporal correlation between the EUV emission from the brightenings observed by TRACE and the hard X-ray (HXR) emission (E > 150 keV) observed by the anticoincidence system (ACS) of the spectrometer SPI on board the ESA INTEGRAL satellite. The correlation between these two emissions is very good, and the HXR sources (RHESSI) late in the flare are located within the two EUV ribbons. These observations are favorable to the explanation that the EUV brightenings mainly result from direct bombardment of the atmosphere by the energetic particles accelerated at the reconnection site, as does the HXR emission. However, if there is a high temperature (T > 20 MK) HXR source close to the loop top, a contribution of thermal conduction to the EUV brightenings cannot be ruled out.     

Business associations and local development: The Okanagan wine industry’s response to NAFTA

Business associations (BAs) represent a widely prevalent institution contingent upon a plethora of regional and industrial contexts around the world. Although their role in local development is rarely highlighted this paper argues that analysis of the structure and strategies of BAs reveals important insights into the problematic nature of external economies, typically based on the willingness of highly independent small firms to share and possibly fund some common service(s). BAs illustrate cooperative behaviour and their fragmentation indicates limits to cooperation and thereby to the contested nature of this particular external economy. Conceptually, the paper interprets BAs as institutional expressions of local cooperation and theorizes their strategy and structure in terms of a ‘logic of exchange’ model. This model defines the relationships between BAs, their members (organizational domains) and governments in terms of the logics of ‘membership’ and ‘influence’ that help understand the opportunities afforded and tensions imposed by the rationale and dynamics of cooperation. Empirically, the paper examines the formation and performance of BAs in the restructuring of the Okanagan’s wine industry that was stimulated by the Free Trade Agreement (FTA) between the US and Canada in 1989 and the North American Free Trade Agreement (NAFTA) of 1991. In the Okanagan wine industry, a newly formed BA was vital in helping firms overcome the crisis generated by free trade. However, subsequent fragmentation that arose out of member disenchantment with logics of influence and membership, indicated limits to local cooperation that may constitute a significant diseconomy in a future crisis.     

Direct migration of ambient seismic data

Utilising ambient seismic energy naturally propagating in the Earth as an alternative approach to active body-wave seismic investigations has been a topic of interest for a number of decades. However, because ambient surface-wave arrivals typically are of much greater amplitude than ambient body-wave energy, significant data signal processing and long recording times are required to mitigate this and other coherent noise sources, and to correlate sufficient reflected body-wave energy to converge to a stable image. Even for these scenarios, identifying and validating imaged body-wave reflection events remain challenging. In active-source investigations, extended imaging condition gathers are used to examine velocity (in)accuracy. Herein, we develop an ambient direct migration approach that uses a novel ambient (deconvolution) extended imaging condition. We simulate synthetic ambient-wavefield seismic data for two different models and use a field data set from Lalor Lake in Manitoba, Canada, to conduct a series of numerical experiments to demonstrate the velocity sensitivity and long-term stationarity of ambient-wavefield seismic data in the migration image domain. Tests with varying global velocity perturbations show a characteristic reflector moveout in deconvolution extended imaging condition gathers that can serve as a diagnostic of reflected ambient body-wave energy. We illustrate that this imaging formalism, under idealised circumstances, gives comparable results to conventional seismic methods, which extends the use of extended imaging condition gather-based image validation to ambient-wavefield seismic data scenarios. We assert that this may be a valuable tool for the validation of ambient migration techniques that to date have yielded largely inconclusive results.     

Initial Calibration of the Atmospheric Imaging Assembly (AIA) on the Solar Dynamics Observatory (SDO)

The Atmospheric Imaging Assembly (AIA) instrument onboard the Solar Dynamics Observatory (SDO) is an array of four normal-incidence reflecting telescopes that image the Sun in ten EUV and UV wavelength channels. We present the initial photometric calibration of AIA, based on preflight measurements of the response of the telescope components. The estimated accuracy is of order 25%, which is consistent with the results of comparisons with full-disk irradiance measurements and spectral models. We also describe the characterization of the instrument performance, including image resolution, alignment, camera-system gain, flat-fielding, and data compression.     

Exploring the Moon's surface for remnants of the lunar mantle 1. Dunite xenoliths in mare basalts. A crustal or mantle origin?

Remotely sensed observations from recent missions (e.g., GRAIL, Kaguya, Chandrayaan‐1) have been interpreted as indicating that the deep crust and upper mantle are close to or at the lunar surface in many large impact basins (e.g., Crisium, Apollo, Moscoviense). If this is correct, the capability of either impact or volcanic processes to transport mantle lithologies to the lunar surface should be enhanced in these regions. Somewhat problematic to these observations and interpretations is that examples of mantle lithologies in the lunar sample collection (Apollo Program, Luna Program, lunar meteorites) are at best ambiguous. Dunite xenoliths in high‐Ti mare basalt 74275 are one of these ambiguous examples. In this high‐Ti mare basalt, olivine occurs in three generations: olivine associated with dunite xenoliths, olivine megacrysts, and olivine microphenocrysts. The dunite xenoliths are anhedral in shape and are generally greater than 800 μm in diameter. The interior of the xenoliths are fairly homogeneous with regard to many divalent cations. For example, the Mg# (Mg/Mg + Fe × 100) ranges from 82 to 83 in their interiors and decreases from 82 to 68 over the 10–30 μm wide outer rim. Titanium and phosphorus X‐ray maps of the xenolith illustrate that these slow diffusing elements preserve primary cumulate zoning textures. These textures indicate that the xenoliths consist of many individual olivine grains approximately 150–200 μm in diameter with low Ti, Al, and P cores. These highly incompatible elements are enriched in the outer Fe‐rich rims of the xenoliths and slightly enriched in the rims of the individual olivine grains. Highly compatible elements in olivine such as Ni exhibit a decrease in the rim surrounding the xenolith, an increase in the incompatible element depleted cores of the individual olivine grains, and a slight decrease in the “interior rims” of the individual olivine grains. Inferred melt composition, liquid lines of descent, and zoning profiles enable the reconstruction of the petrogenesis of the dunite xenoliths. Preservation of primary magmatic zoning (Ti, P, Al) and lack of textures similar to high‐pressure mineral assemblages exhibited by the Mg‐suite (Shearer et al. 2015) indicate that these xenoliths do not represent deep crustal or shallow mantle lithologies. Further, they are chemically and mineralogically distinct from Mg‐suite dunites identified from the Apollo 17 site. More likely, they represent olivine cumulates that crystallized from a low‐Ti mare basalt at intermediate to shallow crustal levels. The parent basalt to the dunite xenolith lithology was more primitive than low‐Ti basalts thus far returned from the Moon. Furthermore, this parental magma and its more evolved daughter magmas are not represented in the basalt sample suite returned from the Taurus‐Littrow Valley by the Apollo 17 mission. The dunite xenolith records several episodes of crystallization and re‐equilibration. During the last episode of re‐equilibration, the dunite cumulate was sampled by the 74275 high‐Ti basalt and transported over a period of 30–70 days to the lunar surface.     

TRACE and Yohkoh Observations of High-Temperature Plasma in a Two-Ribbon Limb Flare

The ability of the Transition Region and Coronal Explorer (TRACE) to image solar plasma over a wide range of temperatures (Te approximately 104-107 K) at high spatial resolution (0&farcs;5 pixels) makes it a unique instrument for observing solar flares. We present TRACE and Yohkoh observations of an M2.4 two-ribbon flare that began on 1999 July 25 at about 13:08 UT. We observe impulsive footpoint brightenings that are followed by the formation of high-temperature plasma (Te greater, similar10 MK) in the corona. After an interval of about 1300 s, cooler loops (Te<2 MK) form below the hot plasma. Thus, the evolution of the event supports the qualitative aspects of the standard reconnection model of solar flares. The TRACE and Yohkoh data show that the bulk of the flare emission is at or below 10 MK. The TRACE data are also consistent with the Yohkoh observations of hotter plasma (Te approximately 15-20 MK) existing at the top of the arcade. The cooling time inferred from these observations is consistent with a hybrid cooling time based on thermal conduction and radiative cooling.