bluuebunny/crossref_metadata_2025 huggingface dataset:
PERSPECTIVE: Linking concepts in the ecology and evolution of invasive plants: network analysis shows what has been most studied and identifies knowledge gaps
Authors: Vanderhoeven Sonia , Brown Cynthia S. , Tepolt Carolyn K. , Tsutsui Neil D. , Vanparys Valérie , Atkinson Sheryl , Mahy Grégory , Monty Arnaud
Published: January 2010

In recent decades, a growing number of studies have addressed connections between ecological and evolutionary concepts in biologic invasions. These connections may be crucial for understanding the processes underlying invaders’ success. However, the extent to which scientists have worked on the integration of the ecology and evolution of invasive plants is poorly documented, as few attempts have been made to evaluate these efforts in invasion biology research. Such analysis can facilitate recognize well‐documented relationships and identify gaps in our knowledge. In this study, we used a network‐based method for visualizing the connections between major aspects of ecology and evolution in the primary research literature. Using the family Poaceae as an example, we show that ecological concepts were more studied and better interconnected than were evolutionary concepts. Several possible connections were not documented at all, representing knowledge gaps between ecology and evolution of invaders. Among knowledge gaps, the concepts of plasticity, gene flow, epigenetics and human influence were particularly under‐connected. We discuss five possible research avenues to better understand the relationships between ecology and evolution in the success of Poaceae, and of alien plants in general.
Safety and Efficacy in HIV‐1‐Infected Patients Treated with Ritonavir‐Boosted Saquinavir Mesylate
Authors: Knechten Heribert , Lutz Thomas , Pulik Piotr , Martin Teodoro , Tappe Andre , Jaeger Hans
Published: January 2010

Objective.  To evaluate the safety, tolerability, and efficacy of ritonavir‐boosted saquinavir 1000/100 mg twice daily administered as a 500 mg film‐coated tablet in HIV‐1‐infected patients.

Methods.  In this open‐label, observational, 24‐week survey conducted in 8 European countries, eligible HIV‐infected participants had been prescribed saquinavir/ritonavir in combination with other nonprotease inhibitor (PI) antiretroviral agents as part of their HIV treatment regimen. The safety (grade 3 or 4 adverse events [AEs]), tolerability (by an investigator‐reported subjective rating system), and efficacy (the percentage of participants with <50 and <400 copies/mL HIV RNA and change from baseline in mean CD4+ cell count) were analyzed for the overall study population and 7 subpopulations.

Results.  The enrolled population included 2122 participants with 1908 completing the study; 44 (2.1%) withdrew prematurely because of AEs, including 7 nontreatment‐related deaths. There were 33 grade 3 or 4 AEs in 29 (1.4%) participants; 7 AEs in 7 (0.3%) participants were considered treatment‐related. Tolerability was reported to be “very good” or “good” in 42% and 25% of participants, respectively. From baseline to week 24, the proportion of participants with HIV RNA <50 copies/mL increased from 31.2% to 47.6% and the proportion with <400 copies/mL increased from 42.5% to 61.4%; the mean CD4+ cell count increased by 75 cells/µL. In the subpopulation analysis, the greatest efficacy benefits occurred in participants who were treatment‐naïve and in those not having received prior PI therapy.

Conclusions.  Treatment with the saquinavir 500 mg film‐coated tablet resulted in few grade 3 or 4 AEs and was well tolerated and effective in a broad population of patients.
Work Hard, Play Hard?: A Comparison of Male and Female Lawyers' Time in Paid and Unpaid Work and Participation in Leisure Activities
Authors: WALLACE JEAN E. , YOUNG MARISA C.
Published: January 2010

Les auteures tentent de déterminer le temps que les professionnels, hommes et femmes, passent à effectuer du travail rémunéré ou non, et la façon dont cela influe sur leur participation à différentes activités de loisirs. Elles se fondent sur des données provenant d'avocats professant dans différents milieux juridiques. Elles constatent que les hommes rapportent consacrer plus de temps au travail rémunéré et aux loisirs, alors que les femmes accordent plus de temps aux travaux ménagers ainsi qu'aux soins des enfants. Les résultats semblent démontrer que les occasions dans l'ensemble plus importantes de loisirs chez les hommes comparées à celles des femmes seraient attribuables à des relations inattendues entre la participation des hommes aux travaux domestiques et aux soins des enfants, et leurs activités de loisirs. Les auteures présentent différentes explications à ces résultats.

There has been a considerable amount of research that documents how women and men spend their time in different work and home tasks. We examine how much time professional women and men spend in paid and unpaid work and how this relates to their participation in different leisure activities. We also explore whether time in paid and unpaid work has gender‐specific effects on leisure participation. In examining these issues, we rely on data from lawyers working in different legal settings. Our results show that, as hypothesized, men report more time in paid work and leisure whereas women devote more time to housework and childcare. An unexpected finding is that the time men spend in housework or childcare is either unrelated or positively related to their leisure participation. These results suggest that men's greater overall opportunities for leisure compared with women's appear to stem from the unanticipated relationships between men's involvement in housework and childcare and their leisure activities. We raise several possible explanations for these findings.
Shareholders' Wealth‐Maximizing Operating Decisions and Risk Management Practices in a Mixed Contracts Economy
Authors: Rao Ramesh K. S. , Gutierrez Genaro J.
Published: January 2010

This paper establishes a critically important positive role for operations management practices and financial hedging. We show that operations management decisions and financial hedging are intertwined, and we advance a framework that can identify their combined effects on investors' wealth. We show that: (a) firms (publicly traded corporations) will optimally hold adequate riskless working capital (e.g., cash) to minimize the cost of obtaining non‐financial inputs, and the magnitude of this cash holding depends on operating details, and (b) operations management and financial hedging can lower firms' cash requirements, and boost productivity, defined as the wealth created in the firm per dollar of invested capital. Productivity‐enhancing practices—by “freeing up” some of the firm's cash—can maximize the investors' wealth. We show that these results obtain because firms' contracts with many of the providers of non‐financial inputs are not traded, and because investors can invest not just in public corporations but also in businesses “outside the markets” (e.g., proprietorships, partnerships, and private equity).
Inventory Control when the Lead‐time Changes
Authors: Axsäter Sven
Published: January 2010

A single‐echelon inventory system with continuous review and Poisson demand is considered. There are standard linear holding and backorder costs but no ordering or set‐up costs. We study a change in the lead‐time, which is rather typical in connection with application of a Just‐In‐Time philosophy. Our main focus is a lead‐time decrease but we also consider a lead‐time increase. Due to the lead‐time change, the optimal steady state solution will also, in general, change. We consider the transient problem of minimizing the costs when bringing the system from its original steady state to the new steady state.
Competing for Shelf Space
Authors: Martínez‐de‐Albéniz Victor , Roels Guillaume
Published: January 2010

In recent years, the competition for shelf space has intensified, as more products now compete for a retail space that has remained roughly constant. In this paper, we analyze the dynamics of this competition in a multi‐supplier retail point. Assuming that sales are shelf space dependent, we consider a retailer that optimizes its shelf space allocation among different products based on their sales level and profit margins. In this context, product manufacturers set their wholesale prices so as to obtain larger shelf space allocations but at the same time keep margins as high as possible. We analyze the equilibrium situation in the supply chain, and find that generally the retailer's and the suppliers' incentives are misaligned, resulting in suboptimal retail prices and shelf space allocations. We however find that the inefficiencies induced by suboptimal shelf space allocation decisions are small relative to those induced by suboptimal pricing decisions.
A critical evaluation of oxidation versus reduction during metamorphism of L and LL group chondrites, and implications for asteroid spectroscopy
Authors: Gastineau‐Lyons Heather K. , McSween Harry Y. , Gaffey Michael J.
Published: January 2010

Abstract— Modal mineralogies of individual, equilibrated (petrologic type 4–6 L and LL chondrites have been measured using an electron microprobe mapping technique, and the chemical compositions of coexisting silicate minerals have been analyzed. Progressive changes in the relative abundances and in the molar Fe/Mn and Fe/Mg ratios of olivine, low‐Ca pyroxene, and diopside occur with increasing metamorphic grade. Variations in olivine/low‐Ca pyroxene ratios (Ol/Px) and in metal abundances and compositions with petrologic type support the hypothesis that oxidation of metallic iron accompanied thermal metamorphism in ordinary chondrites. Modal Ol/Px ratios are systematically lower than normative Ol/Px ratios for the same meteorites, suggesting that the commonly used C.I.P.W. norm calculation procedure may not adequately estimate silicate mineral abundances in reduced chondrites. Ol/Px ratios calculated from visible and near‐infrared (VISNIR) reflectance spectra of the same meteorites are not in agreement with other Ol/Px determinations, possibly because of spectral complexities arising from other minerals in chondrites. Characteristic features in VISNIR spectra are sensitive to the proportions and compositions of olivine and pyroxenes, the minerals most affected by oxidative metamorphism. This work may allow spectral calibration for the determination of mineralogy and petrologic type, and thus may be useful for spectroscopic studies of asteroids.
Petrographic studies of the impact melts from Meteor Crater, Arizona, USA
Authors: Hörz Friedrich , Mittlefehldt David W. , See Thomas H. , Galindo Charles
Published: January 2010

Abstract— We investigated the ballistically dispersed melts from Meteor Crater, Arizona, USA to determine the stratigraphic extent of its melt zone from the compositional relationship of melts and target rocks. Most melt particles are crystallized, hydrated, and oxidized; pristine glasses are rare. Hydration and oxidation occurred at ambient temperatures long after the impact. The preserved glasses are generally clear and texturally homogeneous, but unlike typical impact melts, they have unusually heterogeneous compositions, both within individual particles and from sample to sample. For example, the average SiO2 for individual particles ranges from 43 to 65%. The projectile content is unusually high and it is distributed bimodally, with specific samples containing either 5–10% or 20–30% FeO. These compositional heterogeneities most likely reflect the high carbonate content of the target rocks and the release of copious CO2 that dispersed the melts, thereby terminating melt flow and mixing. The high projectile content and the CO2 depleted residue of purely sedimentary rocks produced mafic melts that crystallized fine‐grained olivine and pyroxene.

The melts fall into three compositional groups reflecting variable proportions of the major target formations, Moenkopi, Kaibab, and Coconino. Least‐square mixing calculations revealed one group to contain 55% Moenkopi, 40% quartz‐rich, upper Kaibab, and 5% meteorite, suggesting a source depth of <30 m from the pre‐impact surface. The other two melt groups have higher contents of meteorite (15–20%) and Kaibab (50–70%) and contain more SiO2 than average Kaibab. The additional quartz may have been derived from Coconino or the upper Kaibab, implying melt depths >90 m or <30 m, respectively. Additional studies, especially hydrocode calculations, are needed to better understand the source depth of these melts and their exceptionally high projectile content.
A hibonite‐corundum inclusion from Murchison: A first‐generation condensate from the solar nebula
Authors: Simon S. B. , Davis A. M. , Grossman L. , McKeegan K. D.
Published: January 2010

Abstract— Through freeze‐thaw disaggregation of the Murchison (CM) carbonaceous chondrite, we have recovered a ˜90 times 75 μm refractory inclusion that consists of corundum and hibonite with minor perovskite. Corundum occurs as small (˜10 μm), rounded grains enclosed in hibonite laths (˜10 μm wide and 30–40 μm long) throughout the inclusion. Perovskite predominantly occurs near the edge of the inclusion. The crystallization sequence inferred petrographically‐corundum followed by hibonite followed by perovskite‐is that predicted for the first phases to form by equilibrium condensation from a solar gas for Ptot ≤5 times 10−3 atm. In addition, the texture of the inclusion, with angular voids between subhedral hibonite laths and plates, is also consistent with formation of the inclusion by condensation. Hibonite has heavy rare earth element (REE) abundances of ˜40 × CI chondrites, light REE abundances ˜20 × CI chondrites, and negative Eu anomalies. The chondrite‐normalized abundance patterns, especially one for a hibonite‐perovskite spot, are quite similar to the patterns of calculated solid/gas partition coefficients for hibonite and perovskite at 10−3 atm and are not consistent with formation of the inclusion by closed‐system fractional crystallization. In contrast with the features that are consistent with a condensation origin, there are problems with any model for the formation of this inclusion that includes a molten stage, relic grains, or volatilization. If thermodynamic models of equilibrium condensation are correct, then this inclusion formed at pressures <5 times 10−3 atm, possibly with enrichments (<1000x) in CI dust relative to gas at low pressures (below 10−4 atm). Both hibonite and corundum have δ17O ≅ δ18O ≅ −50%, indicating formation from an 16O‐rich source. The inclusion does not contain radiogenic 26Mg and apparently did not contain live 26Al when it formed. If the short‐lived radionuclides were formed in a supernova and injected into the early solar nebula, models of this process suggest that 26Al‐free refractory inclusions such as this one formed within the first ˜6 times 105 years of nebular collapse.
The Mazapil meteorite: From paradigm to periphery
Authors: Beech Martin
Published: January 2010

Abstract— The remarkable fact about the Mazapil meteorite is that it fell on the same night, in 1885, that the Andromedid meteor shower underwent a spectacular outburst. The simultaneity of these two events has driven speculation ever since. From ˜1886 to ˜1950 the circumstances of the Mazapil fall were taken, by a number of researchers, as the paradigm that demonstrated the fact that comets were actually swarms of meteoritic boulders. Beginning ˜1950, however, most researchers began to adopted the stance that the timing of the Mazapil fall was nothing more than pure coincidence. The reason behind this change in interpretation stemmed from, amongst other factors, the fact that none of the prominent annual meteor showers could be clearly shown to deliver meteorites. Also, with the introduction of the icy‐conglomerate model for cometary nuclei, by F. Whipple in the early 1950s, it became increasingly clear that only exceptional circumstances would allow for the presence of large meteoritic bodies in cometary streams. Further, by the mid 1960s it had been shown that meteorites could, in fact, be delivered to the Earth from the main belt asteroid region via gravitational resonances. With the removal of the dynamical “barrier” against the delivery of meteorites from the asteroid region, the idea that the Mazapil meteorite could have been part of the Andromedid stream fell into complete disfavor. This being said, we nonetheless present the results of a study concerning the possible properties of the parent object to the Mazapil meteorite based upon the assumption that it was a member of the Andromedid stream. This study is presented to illustrate the point that while cometary showers do not yield meteorites on the ground, this does not, in fact, substantiate the argument that no meteoritic bodies reside in cometary streams. Indeed, we find no good reason to suppose that an object with the characteristics of the Mazapil meteorite could not have been delivered from the Andromedid stream. However, we argue that upon the basis of the actual reported observations and upon the scientific maxim of minimized hypothesis and least assumption it must be concluded that the timing of the fall of the Mazapil meteorite and the occurrence of the Andromedid outburst were purely coincidental.
Light dement geochemistry of the Tagish Lake CI2 chondrite: Comparison with CI1 and CM2 meteorites
Authors: Grady M. M. , Verchovsky A. B. , Franchi I. A. , Wright I. P. , Pillinger C. T.
Published: January 2010

Abstract— We have studied the carbon and nitrogen stable isotope geochemistry of a small pristine sample of the Tagish Lake carbonaceous chondrite by high‐resolution stepped‐combustion mass spectrometry, and compared the results with data from the Orgueil (CI1), Elephant Moraine (EET) 83334 (CM1) and Murchison (CM2) chondrites. The small chip of Tagish Lake analysed herein had a higher carbon abundance (5.81 wt%) than any other chondrite, and a nitrogen content (˜1220 ppm) between that of CI1 and CM2 chondrites. Owing to the heterogeneous nature of the meteorite, the measured carbon abundance might be artificially high: the carbon inventory and whole‐rock carbon isotopic composition (δ13C ≅ +24.4%o) of the chip was dominated by 13C‐enriched carbon from the decomposition of carbonates (between 1.29 and 2.69 wt%; δ13C ≅ +67%o and δ18O ≅ +35%o, in the proportions ˜4:1 dolomite to calcite). In addition to carbonates, Tagish Lake contains organic carbon (˜2.6 wt%, δ13C ≅ −9%o; 1033 ppm N, δ15N ≅ +77%o), a level intermediate between CI and CM chondrites. Around 2% of the organic material is thermally labile and solvent soluble. A further −18% of the organic species are liberated by acid hydrolysis. Tagish Lake also contains a complement of presolar grains. It has a higher nanodiamond abundance (approximately 3650–4330 ppm) than other carbonaceous chondrites, along with ˜8 ppm silicon carbide. Whilst carbon and nitrogen isotope geochemistry is not diagnostic, the data are consistent with classification of Tagish Lake as a CI2 chondrite.
Radar observations of asteroid 1999 JM8
Authors: Benner Lance A. M. , Ostro Steven J. , Nolan Michael C. , Margot Jean‐Luc , Giorgini Jon D. , Hudson R. Scott , Jurgens Raymond F. , Slade Martin A. , Howell Ellen S. , Campbell Donald B. , Yeomans Donald K.
Published: January 2010

Abstract— We report results of delay‐Doppler observations of 1999 JM8 with the Goldstone 8560 MHz (3.5 cm) and Arecibo 2380 MHz (13 cm) radars over 18 days in July‐August 1999. The images place thousands of pixels on the asteroid and achieve range resolutions as fine as 15 m/pixel. The images reveal an asymmetric, irregularly shaped object with a typical overall dimension within 20% of 7 km. If we assume that 1999 JM8's effective diameter is 7 km, then the absolute magnitude, 15.15, and the average Goldstone radar cross section, 2.49 km2, correspond to optical and radar albedos of 0.02 and 0.06, establishing that 1999 JM8 is a dark object at optical and radar wavelengths. The asteroid is in a non‐principal axis spin state that, although not yet well determined, has a dominant periodicity of ˜7 days. However, images obtained between July 31 and August 9 show apparent regular rotation of features from day to day, suggesting that the rotation state is not far from principal axis rotation. 1999 JM8 has regions of pronounced topographic relief, prominent facets several kilometers in extent, numerous crater‐like features between ˜100 m and 1.5 km in diameter, and features whose structural nature is peculiar. Arecibo images provide the strongest evidence to date for a circular polarization ratio feature on any asteroid. Combined optical and radar observations from April 1990 to December 2000 permit computation of planetary close approach times to within ± 10 days over the interval from 293 to at least 2907, one of the longest spans for any potentially hazardous asteroid. Integration of the orbit into the past and future shows close approaches to Earth, Mars, Ceres, and Vesta, but the probability of the object impacting Earth is zero for at least the next nine centuries.
Planar deformation features and impact glass in inclusions from the Vredefort Granophyre, South Africa
Authors: Buchanan P. C. , Reimold W. U.
Published: January 2010

Abstract— The Vredefort Granophyre represents impact melt that was injected downward into fractures in the floor of the Vredefort impact structure, South Africa. This unit contains inclusions of country rock that were derived from different locations within the impact structure and are predominantly composed of quartzite, feldspathic quartzite, arkose, and granitic material with minor proportions of shale and epidiorite. Two of the least recrystallized inclusions contain quartz with single or multiple sets of planar deformation features. Quartz grains in other inclusions display a vermicular texture, which is reminiscent of checkerboard feldspar. Feldspars range from large, twinned crystals in some inclusions to fine‐grained aggregates that apparently are the product of decomposition of larger primary crystals. In rare inclusions, a mafic mineral, probably biotite or amphibole, has been transformed to very fine‐grained aggregates of secondary phases that include small euhedral crystals of Fe‐rich spinel. These data indicate that inclusions within the Vredefort Granophyre were exposed to shock pressures ranging from <5 to 8–30 GPa.

Many of these inclusions contain small, rounded melt pockets composed of a groundmass of devitrified or metamorphosed glass containing microlites of a variety of minerals, including K‐feldspar, quartz, augite, low‐Ca pyroxene, and magnetite. The composition of this devitrified glass varies from inclusion to inclusion, but is generally consistent with a mixture of quartz and feldspar with minor proportions of mafic minerals. In the case of granitoid inclusions, melt pockets commonly occur at the boundaries between feldspar and quartz grains. In metasedimentary inclusions, some of these melt pockets contain remnants of partially melted feldspar grains. These melt pockets may have formed by eutectic melting caused by inclusion of these fragments in the hot (650 to 1610 °C) impact melt that crystallized to form the Vredefort Granophyre.
Noble gas compositions of Antarctic micrometeorites collected at the Dome Fuji Station in 1996 and 1997
Authors: Osawa Takahito , Nagao Keisuke
Published: January 2010

Abstract— The noble gases He, Ne, Ar, Kr, and Xe were measured in 27 individual Antarctic micrometeorites (AMMs) in the size range 60 to 250 μm that were collected at the Dome Fuji Station. Eleven of the AMMs were collected in 1996 (F96 series) and 16 were collected in 1997 (F97 series). One of the F97 AMMs is a totally melted spherule, whereas all other particles are irregular in shape. Noble gases were extracted using a Nd‐YAG continuous wave laser with an output power of 2.5‐3.5 W for ˜5 min. Most particles released measurable amounts of noble gases. 3He/4He ratios are determined for 26 AMMs ((0.85‐9.65) × 10−4). Solar energetic particles (SEP) are the dominant source of helium in most AMMs rather than solar wind (SW) and cosmogenic He. Three samples had higher 3He/4He ratios compared to that of SW, showing the presence of spallogenic 3He. The Ne isotopic composition of most AMMs resembled that of SEP as in the case of helium. Spallogenic 21Ne was detected in three samples, two of which had extremely long cosmic‐ray exposure ages (> 100 Ma), calculated by assuming solar cosmic‐ray (SCR) + galactic cosmic‐ray (GCR) production. These two particles may have come to Earth directly from the Kuiper Belt. Most AMMs had negligible amounts of cosmogenic 21 Ne and exposure ages of <1 Ma. 40Ar/36Ar ratios for all particles (3.9–289) were lower than that of the terrestrial atmosphere (296), indicating an extraterrestrial origin of part of the Ar with a very low 40Ar/36Ar ratio plus some atmospheric contamination. Indeed, 40Ar/36Ar ratios for the AMMs are higher than SW, SEP, and Q‐Ar values, which is explained by the presence of atmospheric 40Ar. The average 38Ar/36Ar ratio of 24 AMMs (0.194) is slightly higher than the value of atmospheric or Q‐Ar, suggesting the presence of SEP‐Ar which has a relatively high 38Ar/36Ar ratio. According to the elemental compositions of the heavy noble gases, Dome Fuji AMMs can be classified into three groups: chondritic (eight particles), air‐affected (nine particles), and solar‐affected (eight particles). The eight AMMs classified as chondritic preserve the heavy noble gas composition of primordial trapped component due to lack of atmospheric adsorption and solar implantation. The average of 129Xe/132Xe ratio for the 16 AMMs not affected by atmospheric contamination (1.05) corresponds to the values in matrices of carbonaceous chondrites (˜1.04). One AMM, F96DK038, has high 129Xe/132Xe in excess of this ratio. Our results imply that most Dome Fuji AMMs originally had chondritic heavy noble gas compositions, and carbonaceous chondrite‐like objects are appropriate candidate sources for most AMMs.
The law of ownership and control of meteorites
Authors: SCHMITT Douglas G.
Published: January 2010

Abstract— Increased commerce in meteorites raises questions about their ownership and control. This article reviews the law in several countries, international law, and considers the legal and ethical issues facing curators wanting to bring finds to the research community and not divert them to a black market. A survey was made of scientists involved in meteorite acquisition in over 20 countries to determine how well various systems work.

Meteorite ownership law is non‐uniform. English Common Law, from which the law in former British colonies including the United States evolved, provides that meteorites are the landowner's property; buried meteorites might be part of the mineral rights. Find reporting is not mandatory. Most Western European countries, and former colonies, have civil codes providing that meteorites are owned by the landowner. In many countries legislation about archaeological treasures modifies earlier meteorite law. The UNESCO Convention on the Means of Prohibiting and Preventing the Illicit Import, Export and Transfer of Ownership of Cultural Property provides for tracking and retrieving from reciprocating states, cultural property including meteorites.

The Antarctic Treaty does not deal with samples exported. In July 2001 the Antarctic Treaty Consultative parties adopted a resolution to discourage non‐scientific collection.

Curators should exercise caution if acquiring specimens of questionable legal ownership.

Governments should be urged to enact laws to (1) discourage non‐scientific collection in pristine areas; (2) encourage collection in populated areas by reasonable incentives to finders, with mandatory find reporting; (3) create efficient export permitting systems allowing exchange of research samples; and (4) retrieve illegally exported meteorites under the UNESCO Cultural Property Convention.
A “mesosiderite” rock from northern Siberia, Russia: Not a meteorite
Authors: TREIMAN Allan H. , LINDSTROM David J. , SCHWANDT Craig S. , FRANCHI Ian A. , MORGAN Matthew L.
Published: January 2010

Abstract— A possible mesosiderite meteorite was found in the area of the Putorana Plateau, Noril'sk district, Siberia, Russia. Although this rock resembles a mesosiderite in its hand‐sample aspect and in having Ni‐bearing iron metal, it is not a meteorite. This inference is based on the lack of a fusion crust, the lack of cosmogenic nuclides, oxygen with terrestrial isotope ratios, and several mineral chemical criteria. Most likely, the rock is from the iron‐metal‐bearing basalts of the Siberian Trap basalt sequence, which are mined for their base and platinum‐group metals. Mesosiderite imposters like this may be recognized by (1) the presence of Cu metal in hand sample or as microscopic blebs in the low‐Ni metal (kamacite), (2) the absence of high‐Ni metal (taenite), and (3) the presence of iron carbide (cohenite) enclosing the kamacite. Even if these macroscopic tests are inconclusive, isotopic and mineral chemical tests will also distinguish rocks like this from mesosiderites.
The Worden meteorite: A new ordinary chondrite fall from Michigan, USA
Authors: VELBEL Michael A. , MATTY David J. , WACKER John F. , LINKE Matt P.
Published: January 2010

Abstract— An ordinary chondrite fall in southeast Michigan, USA (near the crossroads hamlet of Worden in northeast Washtenaw County) penetrated the garage roof of a private home on 1997 September 1. The Worden chondrite comprises silicate matrix, mineral fragments, chondrules, chondrule fragments, and opaque primary phases. Electron microprobe analyses (olivine, Fa23.9; orthopyroxene, Fs20.1, En78.8, Wo1) indicate diagnostic L‐chondrite silicate mineral compositions. Recognizable chondrules and chondrule fragments constitute up to 42 vol%. Chondrule boundaries are readily discernable (especially where chondrules have rims of opaque material) but not sharp, and discrete plagioclase crystals are visible in the devitrified mesostasis of barred olivine chondrules; together, these characteristics suggest petrologic type 5. The spatially averaged ensemble of shock‐related features (optical extinction of olivine grains, minor localized shock melt) suggests assignment of a shock stage of S3.

The 26Al and 22Na activities are typical for an L chondrite. Worden fell near the most recent solar minimum in 1997, and the 22Na production rate should have been at a level approaching the maximum levels due to solar modulation of the galactic cosmic‐ray flux. The low value for the Worden 22Na activity relative to those observed in chondrite falls associated with the 1969 solar maximum and 1976 solar minimum suggests a relatively small preatmospheric size. The 60Co activity confirms the indication of a small body. The 56Co activity was essentially zero, indicating that none of the recovered meteorite contained material exposed to solar cosmic rays.

The Worden chondrite is the fourth documented fall in Michigan, and the fourth stony meteorite recovered in Michigan; all other Michigan meteorites are finds, not observed falls, and are iron meteorites. All Michigan falls to date are ordinary chondrites. The three falls prior to Worden were Allegan (H5) fell 1899; Rose City (H5, brecciated, black (dark matrix)) fell 1921; and Coleman (L6, veined (shocked); Osborn et al., 1997) fell 1994. Worden has a much lighter matrix than Rose City, and is less extensively thermally and shock metamorphosed than either Rose City (Stöffler et al., 1991) or Coleman.
Oral histories in meteoritics and planetary science: IX. Heinrich Wänke
Authors: MARVIN Ursula B.
Published: January 2010

Abstract— In this interview, Heinrich Wänke, a nuclear physicist, describes how he first encountered meteorite studies in 1953 when, after finishing his Ph.D. thesis in Vienna, he joined the research group of Professor Friedrich Paneth at the University of Durham, England. There, he worked on problems relating to uranium‐helium ages of iron meteorites. A year later, Wänke moved with Paneth to the Max‐Planck‐Institut für Chemie at Mainz in Germany. He continued meteorite research but also conducted experiments to measure noble gases in the stratosphere, a project that brought him to America in 1956 where he first met Professor Harold C. Urey, with whom he formed a lasting friendship. After Paneth's early death in 1958, Wänke remained at the Institute in Mainz and pursued research on topics such as the isotopic compositions of cosmogenic noble gases in iron meteorites and the abundances of primordial rare gases implanted by solar wind particles in brecciated stony meteorites. In 1969, Wänke was appointed to fill Paneth's position as a director of the Max‐Planck‐Institut für Chemie just in time for him to lead a wide spectrum of research projects on the lunar rocks and soils. From the geochemical evidence these studies provided, he theorized on the formation of the Moon by the giant impact hypothesis, and proposed a two‐component model for the cosmic composition of the Earth's mantle. His group also investigated the isotopic chemistry of martian meteorites and its bearing on the origin and evolution of Mars, which he viewed as a cored planet that underwent early differentiation without subsequent convective homogenization. In 1980, the Meteoritical Society awarded the Leonard Medal to Heinrich Wänke for his numerous contributions of fundamental importance to meteoritics and planetary science.
Application of MELTS to kinetic evaporation models of FeO‐bearing silicate melts
Authors: ALEXANDER C. M. O'D.
Published: January 2010

Abstract— Incorporation of the MELTS silicate melt solution model into models of evaporation successfully reproduces the evaporation behavior of alkali‐free, FeO‐bearing (≥2 mol%) chondritic melts at temperatures between 1700 and 2000 °C. In conjunction with the Berman CMAS melt solution model for FeO‐poor melts, evaporation of alkali‐free melts can now be modeled over a very wide range of conditions. MELTS‐based evaporation models can also quite successfully reproduce the evaporation behavior of K when Al/(Na + K) > 1. However, reproduction of Na evaporation experiments is much poorer.
Workshop summary on physical and chemical properties of potential Earth impactors
Authors: Huebner W. F. , Greenberg J. M.
Published: January 2010

Abstract— From 2001 June 17 to 25, we held the first international workshop in Erice, Italy, dedicated to the determination of geological and geophysical properties of near‐Earth objects (NEOs). The goal was to develop a roadmap for determining the physical and chemical properties of NEOs in the coming decades to meet the scientific requirements for development of Earth collision avoidance technology. We identified many properties that are desired, but four measurements are needed most critically for any potentially hazardous NEO: (1) its mass, (2) its mass distribution, (3) its material strengths, and (4) its internal structure. Global (whole‐body) properties, such as material strengths and internal structure, can be determined best from the analyses of permeating waves: artificially initiated seismology and multifrequency reflection and transmission radio tomography. Seismology provides the best geophysical (material strengths) data of NEOs composed of consolidated materials while radio tomography provides the best geological data (e.g., the state of fracture) of electrically nonconducting media. Thus, the two methods are complementary: seismology is most suitable for stony and metallic asteroids, while radio tomography is most appropriate for comet nuclei and carbonaceous asteroids. The three main conclusions are (1) remote sensing for physical characterization should be increased, (2) several dedicated NEO missions should be prepared for geophysical and geological investigations, and (3) that it is prudent to develop and prove the technology to make geophysical measurements on NEOs now.
Coeval argon‐40/argon‐39 ages of moldavites from the Bohemian and Lusatian strewn fields
Authors: Schwarz Winfried H. , Lippolt Hans J.
Published: January 2010

Abstract— 40Ar/39Ar ages of four tektites (moldavites) from southern Bohemia (near České Budějovice, Czech Republic) and a tektite from Lusatia (near Dresden, Germany) have been determined by 11 step‐degassing experiments. The purpose of the study was to enlarge the 40Ar/39Ar data base of moldavites and to check the age relations of the Bohemian and Lusatian samples. The mean plateau‐age of the Bohemian samples, which range from 14.42 to 14.70 Ma, is 14.50 ± 0.16 (0.42) (2σ) Ma (errors in parentheses include age error and uncertainty of standard monitor age). The plateau age of the Lusatian sample of 14.38 ± 0.26 (0.44) (2σ) Ma confirms the previously published 40Ar/39Ar age of 14.52 ± 0.08 (0.40) (2σ) Ma, and demonstrates that the fall of Lusatian and Bohemian tektites were contemporaneous. Because of their geochemistry and their ages there is no doubt that the Lusatian tektites are moldavites. Accepting that moldavites are ejecta from the Nördlinger Ries impact, the new ages also date the impact event. This age is slightly younger (about 0.2–0.3 Ma) than the age suggested by earlier K‐Ar determinations.
Heterogeneous agglutinitic glass and the fusion of the finest fraction (F3) model
Authors: Basu Abhijit , Wentworth Susan J. , McKay David S.
Published: January 2010

Abstract—Evidence in favor of the modelfusion of the finest fraction(F3) for the origin of lunar agglutinitic glass has been accruing. They include (1) theoretical expectations that shock pulses should engulf and melt smaller grains more efficiently than larger grains, (2) experimental results of impact shock, albeit at lower than presumed hypervelocity impacts of micrometeorites on the lunar regolith, and (3) new analyses confirming previous results that average compositions of agglutinitic glass are biased towards that of the finest fraction of lunar soils from which they had formed. We add another reason in support of the F3model. Finer grains of lunar soils are also much more abundant. Hence, electrostatic forces associated with the rotating terminator region bring the finest grains that are obviously much lighter than courser grains to the surface of the Moon. This further contributes to the preferential melting of the finest fraction upon micrometeoritic impacts. New backscattered electron imaging shows that agglutinitic glass is inhomogeneous at submicron scale. Composition ranges of agglutinitic glass are extreme and deviate from that of the finest fraction, even by more than an order of magnitude for some components. Additionally, we show how an ilmenite grain upon impact would produce TiO2‐rich agglutinitic glass in complete disregard to the requirements of fusion of the finest fraction. We propose an addition to the F3model to accommodate these observations (i.e., that micrometeorite impacts indiscriminately melt the immediate target regardless of grain size or grain composition). We, therefore, suggest that (1) agglutinitic glass is the sum of (a) the melt produced by the fusion of the finest fraction of lunar soils and (b) the microvolume of the indiscriminate target, which melts at high‐shock pressures from micrometeoritic impacts, and that (2) because of the small volume of the melt and incorporating cold soil grains, the melt quenched so rapidly that it did not mix and homogenize to represent any preferential composition, for example, that of the finest fraction.
A nuclear microprobe study of the distribution and concentration of carbon and nitrogen in Murchison and Tagish Lake meteorites, Antarctic micrometeorites, and IDPs: Implications for astrobiology
Authors: Matrajt G. , Taylor S. , Flynn G. , Brownlee D. , Joswiak D.
Published: January 2010

Abstract— Using a nuclear microprobe, we measured the carbon and nitrogen concentrations and distributions in several interplanetary dust particles (IDPs) and Antarctic micrometeorites (MMs), and compared them to 2 carbonaceous chondrites: Tagish Lake and Murchison. We observed that IDPs are richest in both elements. All the MMs studied contain carbon, and all but the coarse‐grained and 1 melted MM contained nitrogen. We also observed a correlation in the distribution of carbon and nitrogen, suggesting that they may be held in an organic material. The implications for astrobiology of these results are discussed, as small extraterrestrial particles could have contributed to the origin of life on Earth by delivering important quantities of these 2 bio‐elements to the Earth's surface and their gas counterparts, CO2 and N2, to the early atmosphere.
Mineralogy, microtexture, and composition of shock‐induced melt pockets in thi Los Angeles basaltic shergottite
Authors: WALTON Erin L. , SPRAY John G.
Published: January 2010

Abstract— Analytical electron microscopy of shock features in the basaltic shergottite Los Angeles (stone 1) reveals: 1) shock recorded in the bulk sample; and 2) localized pressure and temperature excursions that have generated melt pockets up to 4 mm in diameter. Bulk shock effects include microfaulting (offsets 1–200 μm), mosaicism, deformed exsolution lamellae and planar fracturing in pyroxene, undulose extinction in whitlockite, mechanical twinning in titanomagnetite and ilmenite, and the transformation of plagioclase to maskelynite (≤4% remnant reduced birefringence). The pressure estimates for bulk shock are 35–40 GPa. Localized shock excursions have generated three types of discrete melt zones (0.07 times 1.3 mm to 3.0 times 3.5 mm apparent diameter) possessing glassy to microcrystalline groundmasses. These melt pockets are differentiated on the basis of size, clast volume, and degree of crystallization and vesiculation. Melt veins and melt dikelets emanate from the melt pockets up to 3 mm into the host rock but do not necessarily connect with other melt pockets. The melt pockets were generated by pressure‐temperature excursions of 60–80 GPa and 1600–2000°C, resulting in discrete melting of adjacent host rock minerals at grain boundary margins. Concentric zoning in the margins of clinopyroxenes coincides with a progressive reduction in birefringence as melt pockets are approached. This suggests that the shock excursions were focused as point sources in the wake of the shock front that induced bulk damage.
40Ar‐39Ar chronology of lunar meteorites Northwest Africa 032 and 773
Authors: Fernandes Vera A. , Burgess Ray , Turner Grenville
Published: January 2010

Abstract— The 40Ar‐39Ar dating technique has been applied to the lunar meteorites Northwest Africa 032 (NWA 032), an unbrecciated mare basalt, and Northwest Africa 773 (NWA 773), (composed of cumulate and breccia lithologies), to determine the crystallization age and timing of shock events these meteorites may have experienced. Stepped heating analyses of several different samples of NWA 032 gave complex age spectra but indistinguishable total ages with a mean of 2.779 ± 0.014 Gyr. Possible causes of the complex age spectra obtained from NWA 032 include recoil of 39Ar, or the presence of pre‐shock 40Ar incorporated into shock‐melt veins. The effects of shock veins were investigated by laser fusion of 20 small samples expected to contain varying proportions of the shock veins. The laser ages show a narrow age distribution between 2.61–2.86 Gyr and a mean of 2.73 ± 0.03 Gyr, identical to the total age of ˜2.80 Gyr obtained for the bulk sample. Diffusion calculations based on the stepped heating data indicate that Ar release can be reconciled by release from feldspar (and possibly shock veins) at low temperatures followed by pyroxene at higher temperatures. The exposure age of NWA 032 is 212 ± 11 Myr, and it contains low trapped solar Ar. Stepped heating of cumulate and breccia portions of NWA 773 also give a relatively young age of 2.91 Gyr. The presence of trapped Ar in the breccia makes the age determination of this component less precise, but release of Ar appears to be from the same mineral phase, assumed to be plagioclase, in both lithologies. A marked difference in exposure age between the 2 lithologies also exists, with the breccia having spent 81 Myr longer at the lunar surface; this finding is consistent with the higher trapped Ar content of this lithology. Assuming that 2.80 Gyr and 2.91 Gyr are the crystallization ages of NWA 032 and NWA 773 respectively, these two meteorites are the youngest lunar mare basalts available for study.
Chemistry of the Calcalong Creek lunar meteorite and its relationship to lunar terranes
Authors: HILL D. H. , BOYNTON W. V.
Published: January 2010

Abstract— The Calcalong Creek lunar meteorite is a polymict breccia that contains clasts of both highlands and mare affinity. Reported here is a compilation of major, minor, and trace element data for bulk, clast, and matrix samples determined by instrumental neutron activation analysis (INAA). Petrographic information and results of electron microprobe analyses are included. The relationship of Calcalong Creek to lunar terranes, especially the Procellarum KREEP Terrane and Feldspathic Highlands Terrane, is established by the abundance of thorium, incompatible elements and their KREEP‐like CI chondrite normalized pattern, FeO, and TiO2. The highlands component is associated with Apollo 15 KREEP basalt but represents a variant of the KREEP‐derived material widely found on the moon. Sources of Calcalong Creek's mare basalt components may be related to low‐titanium (LT) and very low‐titanium (VLT) basalts seen in other lunar meteorites but do not sample the same source. The content of some components of Calcalong Creek are found to display similarities to the composition of the South Pole‐Aitken Terrane. What appear to be VLT relationships could represent new high aluminum, low titanium basalt types.
Numerical simulation of temperature effects at fissures due to shock loading
Authors: HEIDER N. , KENKMANN T.
Published: January 2010

Abstract— The localized appearance of specific shock features in target rocks and meteorites such as melt veins and high pressure polymorphs suggests that regions with a local increase in pressure and temperature exist as a shock wave propagates through an inhomogeneous rock. In this paper, we investigate the effect of planar fissures on the local temperature distribution using numerical simulations. Time‐dependent parameters such as temperature, pressure, and displacement are evaluated. The simulation model is based on a shock equation of state for the involved materials, dunite and quartzite, and simulates geometries that were also used in shock‐loading experiments. An artificial gap between the materials simulates an open fissure at the interface. A strong temperature increase occurs at a gap size of 0.1 mm, which potentially can cause melting in a thin layer at the interfaces. The temperature decreases with decreasing gap size. Temperature and pressure excursions at the interface are induced by the closure of the gap, which causes a second shock wave to superpose the primary wave. Open fissures and fractures, which occur ubiquitously in shallow‐buried target rocks and projectiles, thus, act as local pressure and temperature amplyfiers and may be responsible for thin melt vein formation in shocked rocks.