bluuebunny/crossref_metadata_2025 huggingface dataset:
Importance of space weathering simulation products in compositional modeling of asteroids: 349 Dembowska and 446 Aeternitas as examples
Authors: Hiroi Takahiro , Sasaki Sho
Published: February 2010

Abstract— Based on recent progress in simulating space weathering on asteroids using pulse‐laser irradiation onto olivine and orthopyroxene samples, detailed analyses of two of the A and R type asteroid reflectance spectra have been performed using reflectance spectra of laser‐treated samples. The visible‐near‐infrared spectrum of olivine is more altered than that of pyroxene at the same pulse‐laser energy, suggesting that olivine weathers more rapidly than orthopyroxene in space. The same trend can be detected from reflectance spectra of the asteroids, where the more olivine an asteroid has, the redder its 1 μm band continuum can become. Comparison of the 1 μm band continuum slope and the 2/1 μm band area ratio between the asteroids and olivine and pyroxene samples (including the laser‐treated ones) suggests that asteroids may be limited in the degree of space weathering they can exhibit, possibly due to the short life of their surface regolith. Their pyroxenes may also have a limited chemical composition range. Fitting the visible continuum shape and other parts of the spectra (especially the 2μm part) has been impossible with any combination of common rock‐forming minerals such as silicates and metallic irons. However, this study shows, for the first time, excellent fits of reflectance spectra of an A asteroid (Aeternitas) and an R asteroid (Dembowska), including their visible spectral curves, band depths and shapes, and overall continuum shapes. Our results provide estimates that Aeternitas consists of 2% fresh olivine, 93% space‐weathered olivine, 1% space‐weathered orthopyroxene, and 4% chromite, and that Dembowska consists of 1% fresh olivine, 55% space‐weathered olivine, and 44% space‐weathered orthopyroxene. These results suggest that space weathering effects maybe important to the interpretation of asteroid reflectance spectra, even those with deep silicate absorption bands. Modified Gaussian model deconvolutions of the laser‐irradiated olivine samples show that their identity as olivine remained. The most recent submicroscopic mineralogical analyses have revealed that the laser‐irradiated olivine samples contain nanophase iron particles similar to those in space‐weathered lunar samples.
Leonid fluxes: 1994–1998 activity patterns
Authors: MaTRIGO‐RODRIGUEZ Josep , Fabregat Juan , Llorca Jordi
Published: February 2010

Abstract— The Leonid meteor shower was observed worldwide in 1998 November in an intensive campaign without precedent. During this international effort ∼35 500 meteors were reported by members and collaborators of the International Meteor Organization (IMO) using a standard methodology. Despite the absence of a meteor storm in 1998, the rich observational data allow us to obtain a detailed unprecedented knowledge of the stream structure between 1994 and 1998.
The NEAR‐Shoemaker x‐ray/gamma‐ray spectrometer experiment: Overview and lessons learned
Authors: Trombka J. I. , Nittler L. R. , Starr R. D. , Evans L. G. , Mccoy T. J. , Boynton W. V. , Burbine T. H. , Brückner J. , Gorenstein P. , Squyres S. W. , Reedy R. C. , Goldsten J. O. , Lim L. , Hurley K. , Clark P. E. , Floyd S. R. , Mcclanahan T. P. , Mccartney E. , Branscomb J. , Bhangoo J. S. , Mikheeva I. , Murphy M. E.
Published: February 2010

Abstract— The near‐Earth asteroid rendezvous (NEAR)‐Shoemaker remote‐sensing x‐ray/gamma‐ray spectrometer (XGRS) completed more than a year of operation in orbit and on the surface of 433 Eros. Elemental compositions for a number of regions on the surface of Eros have been derived from analyses of the characteristic x‐ray and gamma‐ray emission spectra. The NEAR XGRS detection system was included as part of the interplanetary network (IPN) for the detection and localization of gamma‐ray bursts (GRBs). Preliminary results for both the elemental composition of the surface of Eros and the detection of GRBs have been obtained. In addition to the science results, the design and operation of the NEAR XGRS is considered. Significant information important for the design of future remote sensing XGRS systems has been obtained and evaluated. We focus on four factors that became particularly critical during NEAR: (1) overall spacecraft design, (2) selection of materials, (3) increase of the signal‐to‐noise ratio and (4) knowledge of the incident solar x‐ray spectrum.
Elemental composition from gamma‐ray spectroscopy of the NEAR‐Shoemaker landing site on 433 Eros
Authors: Evans Larry G. , Starr Richard D. , Brückner Johannes , Reedy Robert C. , Boynton William V. , Trombka Jacob I. , Goldsten John O. , Masarik Jozef , Nittler Larry R. , Mccoy Timothy J.
Published: February 2010

Abstract— Elemental composition and composition ratios derived from gamma‐ray measurements collected by the NEAR‐Shoemaker spacecraft while on the surface of 433 Eros are reported. Performance of the gamma‐ray spectrometer (GRS) during cruise and orbit is reviewed. The best gamma‐ray data were collected on the surface of Eros after the spacecraft's controlled descent on 2001 February 12. Methods used in spectral analysis, to convert peak areas to incident photons, and photons to elemental composition are described in some detail. The elemental abundance of K and the Mg/Si, Fe/Si, Si/O and Fe/O abundance ratios were determined. The Mg/Si and Si/O ratios and the K abundance are roughly chondritic, but the Fe/Si and Fe/O ratios are low compared to expected chondritic values. Three possible explanations for the apparent Fe depletion are considered.
X‐ray fluorescence measurements of the surface elemental composition of asteroid 433 Eros
Authors: Nittler Larry R. , Starr Richard D. , Lim Lucy , Mccoy Timothy J. , Burbine Thomas H. , Reedy Robert C. , Trombka Jacob I. , Gorenstein Paul , Squyres Steven W. , Boynton William V. , Mcclanahan Timothy P. , Bhangoo Jesse S. , Clark Pamela E. , Murphy Mary Ellen , Killen Rosemary
Published: February 2010

Abstract— We report major element ratios determined for the S‐class asteroid 433 Eros using remote‐sensing x‐ray fluorescence spectroscopy with the near‐Earth asteroid rendezvous Shoemaker x‐ray spectrometer (XRS). Data analysis techniques and systematic errors are described in detail. Data acquired during five solar flares and during two extended “quiet Sun” periods are presented; these results sample a representative portion of the asteroid's surface. Although systematic uncertainties are potentially large, the most internally consistent and plausible interpretation of the data is that Eros has primitive Mg/Si, Al/Si, Ca/Si and Fe/Si ratios, closely similar to H or R chondrites. Global differentiation of the asteroid is ruled out. The S/Si ratio is much lower than that of chondrites, probably reflecting impact‐induced volatilization and/or photo‐ or ion‐induced sputtering of sulfur at the surface of the asteroid. An alternative explanation for the low S/Si ratio is that it reflects a limited degree of melting with loss of an FeS‐rich partial melt. Size‐sorting processes could lead to segregation of Fe‐Ni metal from silicates within the regolith of Eros; this could indicate that the Fe/Si ratios determined by the x‐ray spectrometer are not representative of the bulk Eros composition.
Exploration of quantitative kinetic models for the evaporation of silicate melts in vacuum and in hydrogen
Authors: ALEXANDER C. M. O'D.
Published: February 2010

Abstract— Two basic approaches (pure component reference (PCR) and equilibrium reference (EQR)) to modeling silicate melt evaporation are explored. The PCR model calculates the maximum possible evaporation rates of the pure oxides from their equilibrium vapor pressures and rescales these rates according to the activities of the oxides in the silicate melts and the melt densities. The EQR model calculates the maximum possible evaporation rates based on the equilibrium vapor pressures of the melts. Differences between the calculated and experimentally determined evaporation rates are accounted for with evaporation (αevap) coefficients that are only dependent on temperature. Two versions of the PCR model, Cases 1 and 2, are explored to try to resolve apparently contradictory conclusions about the composition of the evaporating species based on Mg and Si isotope fractionation during evaporation (species are not in thermodynamic equilibrium proportions) and direct measurements of gas species in Langmuir experiments (species are in roughly equilibrium proportions). The Case 2 and EQR models cannot explain the observed isotope fractionations unless evaporation occurred under non‐Rayleigh conditions, either because there was significant recondensation during the experiments or because diffusion was playing a limiting role.

Whether or not the role of diffusion is included, the PCR and EQR models are able to reproduce the elemental results of evaporation experiments of “chondritic” melts from temperatures of 1700 to 2000 °C, and up to mass losses of about 95%. However, the models underestimate absolute evaporation rates in very Ca‐ and Al‐rich melts. This may reflect errors in the model used to estimate oxide activities. The EQR model can only reproduce the observed evaporation behavior of Na if, unlike the other oxides, its αevap coefficient is close to unity.

Based on available diffusion data, diffusion is not slow enough in “chondritic” or forsteritic melts to explain the isotopic fractionations of Mg and O in the evaporation experiments, but it may play a role in limiting Si isotope fractionation. Provided recondensation was not a significant factor in the experiments, at present PCR Case 1 appears to be the best model if both the Langmuir and the isotopic fractionation experiments are to be explained.
Formation of orange hibonite, as inferred from some Allende inclusions
Authors: SIMON S. B. , DAVIS A. M. , GROSSMAN L.
Published: February 2010

Abstract— We studied three fluffy Type A refractory inclusions from Allende that contain orange hibonite. The melilite in the present samples is very Al‐rich, averaging Åk6, Åk14, and Åk12 in the three samples studied. Hibonite in two inclusions, unlike that in Murchison, has low rare earth element abundances of <10 × CI; in the other inclusion, the hibonite, melilite and perovskite have Group II‐like patterns. The hibonite and melilite in all three inclusions studied have excess 26Mg consistent with (26Al/27Al)I = 5 × 10−5. Much of the hibonite and some of the spinel in these inclusions is corroded. These phases are found enclosed in melilite, but based on bulk compositions and phase equilibria, hibonite should not be an early‐crystallizing phase in these inclusions. We conclude that the hibonite and probably some of the spinel is relic. Reversely zoned melilite, rounded spinel and isotopically heavy Mg in the inclusions probably reflect reheating events that involved melting and evaporation. Alteration of the gehlenitic melilite gave rise to some rare phases, including corundum and nearly pure CaTs pyroxene.

Studies have shown that blue hibonite contains Ti3+ while orange hibonite does not (Ihinger and Stolper, 1986; Beckett et al., 1988). Orange hibonite formed either under oxidizing conditions (such as at oxygen fugacities at least seven orders of magnitude greater than that of a solar gas at 1700 K), or under conditions reducing enough (e.g., solar) that it contained Ti3+, which was later oxidized in situ. Although V and Ce oxides are volatile at the temperature and range of oxygen fugacities at which orange hibonite is known to be stable, we find that (a) the hibonite is V‐rich (∼1 wt% V2O3) and (b) there are no negative Ce anomalies in Allende hibonite. This indicates that the hibonite did not form by condensation under oxidizing conditions. In addition, there are slight excesses of Ti + Si cations relative to Mg + Fe cations (up to 0.1 of 0.8 cations per 19 oxygen anions), probably reflecting the original presence of Ti3+. The results of this study strongly support the suggestion (Ihinger and Stolper, 1986) that Allende hibonite originally formed under reducing conditions and was later oxidized. Oxygen fugacities within ∼2–3 orders of magnitude of that of a solar gas are implied; otherwise, strong Ce and V depletions would be observed.
Formation of resurge gullies at impacts at sea: The Lockne crater, Sweden
Authors: DALWIGK Ilka von , ORMÖ Jens
Published: February 2010

Abstract— The Lockne crater in Sweden is a marine‐target crater, formed in a shelf sea, approximately 460 Ma ago. The crater structure consists of an inner crater surrounded by an outer, inclined surface that extends to almost 12 km from the center.

Marine craters differ in several respects from craters formed on land. One special feature is the formation of resurge gullies excavated by the erosional force of the resurging sea water after the impact. The formation of these gullies strongly depends on the ratio crater‐rim height to water depth, as well as on the size of the impact structure. Such gullies are known from very few marine‐target craters. At the Lockne impact site, four gullies are identified, each of which cuts radially through the rim of the outer crater.

The rapid collapse of that part of the crater cavity, which formed in the seawater, resulted in forceful flooding of the crater. The resurging seawater not only contained fallback‐ejecta; on its way towards the cavity on the sea‐bottom it incorporated fractured lithologies from the sea‐bottom as well. This entrained material disintegrated during transport and constitutes today the dominantly monomict lower part of the resurge sequence. The resurge flood was highly turbulent, highly erosive, and developed to a probable hyperconcentrated flow or a possible water flood. The erosion in the gullies proceeded as headward erosion down to the transition zone between the brecciated and the less disintegrated crystalline basement.
A new metal‐rich chondrite grouplet
Authors: WEISBERG Michael K. , PRINZ Martin , CLAYTON Robert N. , MAYEDA Toshiko K. , SUGIURA Naoji , ZASHU Shigeo , EBIHARA Mitsuru
Published: February 2010

Abstract— A new grouplet of primitive, metal‐rich chondrites, here called the CB (C, carbonaceous; B, bencubbinite) chondrites, has been recognized. It includes Bencubbin, Weatherford, Hammadah al Hamra (HH) 237 and Queen Alexandra Range (QUE) 94411, paired with QUE 94627. Their mineral compositions, as well as their oxygen and nitrogen isotopic compositions, indicate that they are closely related to the CR and CH chondrites, all of which are members of the more inclusive CR clan. CB chondrites have much greater metal/silicate ratios than any other chondrite group, widely increasing the range of metal/silicate fractionation recorded in solar nebular processes. They also have the greatest moderately volatile lithophile element depletions of any chondritic materials. Metal has compositional trends and zoning patterns that suggest a primitive condensation origin, in contrast with metal from other chondrite groups. CB chondrites, as well as other CR clan chondrites, have much heavier nitrogen (higher 15N/14N) than that in other chondrite groups. The primitive characteristics of the CB chondrites suggest that they contain one of the best records of early nebular processes.

Another chondrite, Grosvenor Mountains 95551, is petrographically similar to the CB chondrites, but its mineral and oxygen and nitrogen isotope compositions indicate that it formed from a different nebular reservoir.
Dhofar 081: A new lunar highland meteorite
Authors: GRESHAKE A. , SCHMITT R. T. , STÖFFLER D. , PÄTSCH M. , SCHULTZ L.
Published: February 2010

Abstract— The lunar meteorite Dhofar 081, found as a single fragment of 174 g in the Dhofar region of Oman, is a shocked feldspathic fragmental highland breccia dominated by anorthosite‐rich lithic and mineral clasts embedded into a fine‐grained mostly shock melted clastic matrix. Major mineral phases in the bulk rock are Ca‐rich plagioclase (An96.5–99.5), pyroxene (FS21.9–46.2Wo3.0–41.4), and olivine (Fa29.3–47.8); accessory phases include Fe‐Ni metal, ilmenite, and Ti‐Cr‐rich spinel. Dhofar 081 contains subordinate crystalline fragments of large anorthosites, intersertal impact‐melt rocks, microporphyritic impact‐melt breccias, dark fine‐grained impact‐melt breccias, large cataclastic feldspars, and irregularly shaped brown glass clasts. Mafic components are rare and no genuine regolith components were found in the sections studied. Minerals in Dhofar 081 show homogeneously distributed shock features: intergranular recrystallization, strong fracturing and mosaicism in feldspar as well as a high density of mostly irregular fractures in pyroxene and olivine. Localized impact melting caused by one or several impacts led to a strong lithification. Based on these effects an equilibration shock pressure of about 15–20 GPa is estimated for the strongest shock event in Dhofar 081. Devitrification of the “glassy” material in the rock indicates thermal annealing after shock melting suggesting that the 15–20 GPa shock event predated the ejection event. According to the concentrations of implanted solar noble gases Dhofar 081 represents a polymict clastic breccia deposit with possibly a minor regolith component. A similar noble gas record of Dhofar 081 and MacAlpine Hills 88104/05 suggests the possibility of a source crater pairing of both meteorites. As indicated by noble gas measurements pairing of Dhofar 081 with the other lunar meteorites found in Oman, Dhofar 025 and Dhofar 026, is unlikely.
Carbon‐silicate aggregates in the CH chondrite Pecora Escarpment 91467: A carrier of heavy nitrogen of interstellar origin
Authors: SUGIURA N. , ZASHU S.
Published: February 2010

Abstract— Scanning electron microscopy and secondary ion mass spectrometry of the unequilibrated CH chondrite Pecora Escarpment (PCA) 91467 revealed four carriers of isotopically heavy N: (1) aggregates of carbonaceous material and silicates, (2) iron‐nickel metal grains with fine Fe‐Cr sulfide inclusions, (3) Si‐rich Fe‐Ni metal associated with Fe‐sulfide and (4) hydrated areas in the matrix. N in carbon‐silicate aggregates is isotopically heavy (δ15N is as high as 2500%0), whereas the other elements are isotopically normal, suggesting interstellar origin of carbonaceous material in the aggregates. Based on isotopic and textural evidence, we suggest that the carriers (2) and (3) were formed by brief heating in the solar nebula, whereas the carrier (4) was formed in a parent‐body asteroid. The carbon‐silicate aggregates are likely to be related to interstellar graphite found in Murchison and may also be the source of heavy N in bencubbinites.
Remote sensing and geological studies of the Hadley‐Apennine region of the Moon
Authors: BLEWETT David T. , HAWKE B. Ray
Published: February 2010

Abstract—We have used data from theClementineandLunar Prospectorspacecraft in conjunction with reflectance spectra collected with Earth‐based telescopes to study the geology of the Hadley‐Apennine portion of the lunar Imbrium basin. The Apennine Mountains and the Imbrium backslope are composed of Imbrium basin ejecta with a noritic or anorthositic norite composition. We find that the two major facies of Imbrium ejecta, the Apenninus material and the Alpes Formation, differ in iron and titanium content. “Pure” anorthosite has tentatively been identified in the ejecta of the crater Conon, based on low‐iron content. A difference in Th and rare earth element (REE) abundance between the northeast Apennine Mountains (lower) and the southwest Apennines (higher) is noted. Pyroclastic deposits are common in the region and are dominated by mare basalt material, probably plug rock ejected in vulcanian eruptions. The Apennine Bench Formation, which is likely to be a deposit of non‐mare volcanic material, has an Fe, Ti and Th composition consistent with that of Apollo 15 KREEP basalt samples thought to be fragments of the Bench. Aristillus crater is a Th and REE hot spot, and the stratigraphy of the impact target site has been reconstructed from knowledge of the composition of the crater interior and exterior deposits. We infer that the target consisted of highland basement, KREEP plutonics and volcanics, and both high‐ and low‐Ti mare basalt.
Vesta, Vestoids, and the howardite, eucrite, diogenite group: Relationships and the origin of spectral differences
Authors: Burbine T. H. , Buchanan P. C. , Binzel R. P. , Bus S. J. , Hiroi T. , Hinrichs J. L. , Meibom A. , Mccoy T. J.
Published: February 2010

Abstract— Spectra of asteroid 4 Vesta and 21 small (estimated diameters less than 10 km) asteroids with Vesta‐like spectral properties (Vestoids) were measured at visible and near‐infrared wavelengths (∼0.44 to ∼1.65 μm). All of the measured small asteroids (except for 2579 Spartacus) have reflectance spectra consistent with surface compositions similar to eucrites and howardites and consistent with all being derived from Vesta. None of the observed asteroids have spectra similar to diogenites. We find no spectral distinction between the 15 objects tabulated as members of the Vesta dynamical family and 6 of the 7 sampled “non‐family” members that reside just outside the semi‐major axis (a), eccentricity (e), and inclination (i) region of the family. The spectral consistency and close orbital (a‐e‐i) match of these “non‐family” objects to Vesta and the Vesta family imply that the true bounds of the family extend beyond the subjective cut‐off for membership. Asteroid 2579 Spartacus has a spectrum consistent with a mixture of eucritic material and olivine. Spartacus could contain olivine‐rich material from Vesta's mantle or may be unrelated to Vesta altogether. Laboratory measurements of the spectra of eucrites show that samples having nearly identical compositions can display a wide range of spectral slopes. Finer particle sizes lead to an increase in the slope, which is usually referred to as reddening. This range of spectral variation for the best‐known meteoritic analogs to the Vestoids, regardless of whether they are actually related to each other, suggests that the extremely red spectral slopes for some Vestoids can be explained by very fine‐grained eucritic material on their surfaces.
Ferrous oxide in Mercury's crust and mantle
Authors: Robinson M. S. , Taylor G. J.
Published: February 2010

Abstract— ‐Mercury has widespread plains deposits proposed to be volcanic in origin. In a Mariner 10 color‐derived parameter image, sensitive to FeO and maturity, these volcanic plains have a value equivalent to, or slightly elevated above, the hemispheric average, thus implying FeO equivalent to, or slightly less than, the hemispheric average (∼3 wt% FeO). Since FeO has a solid/liquid distribution coefficient ∼1 during partial melting, we estimate the mantle of Mercury to have an FeO abundance equal to the lava flows. This is consistent with models that predict Mercury was assembled from planetesimals formed near the planet's current position. This new estimate of Mercury's bulk FeO (∼3 wt%) is consistent with data for the other terrestrial planets that suggest there was a radial gradient in FeO in the solar nebula.
Formation of mesosiderites by fragmentation and reaccretion of a large differentiated asteroid
Authors: SCOTT Edward R. D. , HAACK Henning , LOVE Stanley G.
Published: February 2010

Abstract—We propose that mesosiderites formed when a 200–400 km diameter asteroid with a molten core was disrupted by a 50–150 km diameter projectile. To test whether impacts can excavate core iron and mix it with crustal material, we used a low‐resolution, smoothed‐particle hydrodynamics computer simulation. For 50–300 km diameter differentiated targets, we found that significant proportions of scrambled core material (and hence potential mesosiderite metal material) could be generated. For near‐catastrophic impacts that reduce the target to 80% of its original diameter and about half of its original mass, the proportion of scrambled core material would be about 5 vol%, equivalent to ∼10 vol% of mesosiderite‐like material. The paucity of olivine in mesosiderites and the lack of metal‐poor or troilite‐rich meteorites from the mesosiderite body probably reflect biased sampling. Mesosiderites may be olivine‐poor because mantle material was preferentially excluded from the metal‐rich regions of the reaccreted body. Molten metal globules probably crystallized around small, cool fragments of crust hindering migration of metal to the core. If mantle fragments were much hotter and larger than crustal fragments, little metal would have crystallized around the mantle fragments allowing olivine and molten metal to separate gravitationally. The rapid cooling rates of mesosiderites above 850 °C can be attributed to local thermal equilibration between hot and cold ejecta. Very slow cooling below 400 °C probably reflects the large size of the body and the excellent thermal insulation provided by the reaccreted debris. We infer that our model is more plausible than an earlier model that invoked an impact at ∼1 km/s to mix projectile metal with target silicates. If large impacts cannot effectively strip mantles from asteroidal cores, as we infer, we should expect few large eroded asteroids to have surfaces composed purely of mantle or core material. This may help to explain why relatively few olivine‐rich (A‐type) and metal‐rich asteroids (M‐type) are known. Some S‐type asteroids may be scrambled differentiated bodies.
Exposure age, terrestrial age and pre‐atmospheric radius of the Chinguetti mesosiderite: Not part of a much larger mass
Authors: WELTEN K. C. , BLAND P. A. , RUSSELL S. S. , GRADY M. M. , CAFFEE M. W. , MASARIK J. , JULL A. J. T. , WEBER H. W. , SCHULTZ L.
Published: February 2010

Abstract— We measured the concentrations of the cosmogenic radionuclides 14C (half‐life = 5.73 × 103 years) in the bulk and of 10Be (1.5 × 106 years), 26Al (7.05 × 105 years), 36C1 (3.01 × 105 years) and the light noble gases in metal and stone fractions of the Chinguetti meteorite to investigate the controversial claim that the 4.5 kg mesosiderite is part of a much larger mass in the Mauritanian desert. Based on the 36C1‐36Ar, 10Be‐21Ne and 26Al‐21Ne pairs in the metal fraction, we derive an average cosmic‐ray exposure age of 66 ± 7 Ma. Chinguetti is now the third out of 20 mesosiderites with an exposure age between 60 and 70 Ma. This may be the first hint of a major impact on the parent body of the mesosiderites, which show ages ranging from 10 to 300 Ma (Terribilini et al., 2000). From the 14C‐10Be pair we derive a terrestrial age of 18 ± 1 ka, which seems too recent to be consistent with the original description of the main mass having a heavily wind‐eroded base, overhung by the upper part of the meteorite. Finally, from the radionuclide concentrations in combination with Monte‐Carlo based calculations, we conclude that our sample of Chinguetti was irradiated at a depth of ∼15 cm in an object not larger than 80 cm in radius. This is the most compelling evidence against the reports that the Chinguetti mesosiderite is a small fragment of a mass 100 m long and 40 m high.
Noble gases in enstatite chondrites I: Exposure ages, pairing, and weathering effects
Authors: PATZER Andrea , SCHULTZ Ludolf
Published: February 2010

Abstract— Cosmic‐ray exposure ages calculated from cosmogenic noble gas nuclides are reported for 57 enstatite (E) chondrites, 43 of them were measured for the first time. With a total of 62 individual E chondrites (literature and this data, corrected for pairing) the observed spectrum of ages ranges between 0.07 and 66 Ma. Three clusters seem to develop at about 3.5, 8, and 25 Ma, respectively. Since the uncertainty of ages is estimated to be ∼20% (in contrast to 10 to 15% for ordinary chondrites) and the number of examined samples is still comparatively small, these peaks have to be confirmed by more measurements. Regarding the two subgroups, EH and EL chondrites, no systematic trend is apparent in the distribution of cosmic‐ray exposure ages.

Several E chondrites yield significantly lower 38Ar ages compared to those calculated from cosmogenic 3He and 21Ne. For these E chondrites, we suggest a reduction of cosmogenic 38Ar as a result of weathering. In order to prove the possible influence of terrestrial alteration on the cosmogenic noble gas record of E‐chondritic material, we simulated terrestrial weathering in an experiment of 12 weeks duration. The treatment showed that a significant amount of cosmogenic 38Ar is lost on Earth by the influence of water.
Cosmic‐ray prdocution rates of helium, neon and argon isotopes in H chondrites based on chlorine‐36/argon‐36 ages
Authors: LEYA I. , GRAF Th. , NISHIIZUMI K. , WIELER R.
Published: February 2010

Abstract— We present the concentrations and isotopic compositions of He, Ne, and Ar for nonmagnetic fractions and bulk samples of 17 H chondrites which were recently investigated for their 36Cl‐36Ar cosmic‐ray exposure ages (Graf et al., 2001). All selected meteorites are observed falls with cosmic‐ray exposure ages close to the 7 Ma peak. The rare gas data are consistent with 10Be and 36C1 production rates in the metal phase. Remarkably, only 1 out of the 17 H chondrites, Bath, shows clear indications for a complex exposure history. Based on rare gas concentrations and 36Cl‐36Ar exposure ages, 21Ne production rates as a function of 22Ne/21 Ne and a mean 38Ar production rate are determined. The results confirm model calculations which predict that the relationship between 21Ne production rates and 22Ne/21Ne is ambiguous for high shielding. Besides the mean 38Ar production rate we also give production rate ratios P(38Ar from Ca)/P(38Ar from Fe). They vary between 10 and 77, showing no significant correlation with 38Ar concentrations or 22Ne/21Ne. By investigating the metal separates, Graf et al. (2001) found significant 3He deficits for 6 out of the 17 meteorites. For the nonmagnetic fractions and bulk samples investigated here, the data points in a 3He/21Ne vs. 22Ne/21Ne diagram plot in the area defined by most of the H chondrites. This means that 3He deficits in the metal phase are much more pronounced than in silicate minerals and we will argue that 3H diffusive losses in meteorites should be the rule rather than the exception. The 21Ne exposure ages, calculated on the basis of modeled 21Ne production rates, confirm the assumption by Graf et al. (2001) that the H5 chondrites with low 3He/38Ar in the metal formed in a separate event than those with normal 3He/38Ar ratios. The data can best be interpreted by assuming that the prominent 7 Ma exposure age peak of the H chondrites is due to at least two events about 7.0 and 7.6 Ma ago.
Comment on “Evidence for a very high carbon/iridium ratio in the Tunguska impactor” by K. L. Rasmussen, H. J. F. Olsen, R. Gwozdz and E. M. Kolesnikov
Authors: Jull A. J. T. , Burr G. S. , Kring D. A.
Published: February 2010

Abstract— We discuss possible evidence for a dilution of 14C caused by the Tunguska impact event, proposed by Rasmussen et al. (1999). The results presented in that paper and other available information do not support this hypothesis.
Evidence for shock metamorphism in sandstones from the Libyan Desert Glass strewn field
Authors: KLEINMANN Barbara , HORN Peter , LANGENHORST Falko
Published: February 2010

Abstract— Microscopic analysis of sandstones from the southern Libyan Desert Glass strewn field reveals a sequence of progressive deformation features, which range from unaffected rock to extreme brecciation. The quartz grains show a wide range of deformation features: crushing and fracturing, undulatory extinction, mosaicism, oriented cleavage, partial isotropization and multiple sets of planar deformation features. This preliminary report provides the first description of these shock indicators, which are typical for hypervelocity impact, in bedrock material that is assumed to be related to the Libyan Desert Glass.
Direct Detection of Methicillin Resistance in
Staphylococcus aureus
in Blood Culture Broth by Use of a Penicillin Binding Protein 2a Latex Agglutination Test
Authors: Qian Qinfang , Venkataraman Lata , Kirby James E. , Gold Howard S. , Yamazumi Toshiaki
Published: February 2010

We studied the utility of performing a penicillin binding protein 2a latex agglutination (PBP-LA) assay directly on Bactec blood culture broth samples containing
Staphylococcus aureus
to rapidly detect methicillin resistance. The sensitivity, specificity, positive predictive value, and negative predictive value of this method were 94.1%, 97.5%, 98%, and 92.9%, respectively.
InhA1, NprA, and HlyII as Candidates for Markers To Differentiate Pathogenic from NonpathogenicBacillus cereusStrains
Authors: Cadot Céline , Tran Seav-Ly , Vignaud Marie-Léone , De Buyser Marie-Laure , Kolstø Anne-Brit , Brisabois Anne , Nguyen-Thé Christophe , Lereclus Didier , Guinebretière Marie-Hélène , Ramarao Nalini
Published: February 2010

Bacillus cereusis found in food, soil, and plants, and the ability to cause food-borne diseases and opportunistic infection presumably varies among strains. Therefore, measuring harmful toxin production, in addition to the detection of the bacterium itself, may be key for food and hospital safety purposes. All previous studies have focused on the main known virulence factors, cereulide, Hbl, Nhe, and CytK. We examined whether other virulence factors may be specific to pathogenic strains. InhA1, NprA, and HlyII have been described as possibly contributing toB. cereuspathogenicity. We report the prevalence and expression profiles of these three new virulence factor genes among 57B. cereusstrains isolated from various sources, including isolates associated with gastrointestinal and nongastrointestinal diseases. Using PCR, quantitative reverse transcriptase PCR, and virulencein vivoassays, we unraveled these factors as potential markers to differentiate pathogenic from nonpathogenic strains. We show that thehlyIIgene is carried only by strains with a pathogenic potential and that the expression levels ofinhA1andnprAare higher in the pathogenic than in the nonpathogenic group of strains studied. These data deliver useful information about the pathogenicity of variousB. cereusstrains.
Human Rhinovirus 14 Enters Rhabdomyosarcoma Cells Expressing ICAM-1 by a Clathrin-, Caveolin-, and Flotillin-Independent Pathway
Authors: Khan Abdul Ghafoor , Pickl-Herk Angela , Gajdzik Leszek , Marlovits Thomas C. , Fuchs Renate , Blaas Dieter
Published: February 2010

Intercellular adhesion molecule 1 (ICAM-1) mediates binding and entry of major group human rhinoviruses (HRVs). Whereas the entry pathway of minor group HRVs has been studied in detail and is comparatively well understood, the pathway taken by major group HRVs is largely unknown. Use of immunofluorescence microscopy, colocalization with specific endocytic markers, dominant negative mutants, and pharmacological inhibitors allowed us to demonstrate that the major group virus HRV14 enters rhabdomyosarcoma cells transfected to express human ICAM-1 in a clathrin-, caveolin-, and flotillin-independent manner. Electron microscopy revealed that many virions accumulated in long tubular structures, easily distinguishable from clathrin-coated pits and caveolae. Virus entry was strongly sensitive to the Na+/H+ion exchange inhibitor amiloride and moderately sensitive to cytochalasin D. Thus, cellular uptake of HRV14 occurs via a pathway exhibiting some, but not all, characteristics of macropinocytosis and is similar to that recently described for adenovirus 3 entry via αvintegrin/CD46 in HeLa cells.
Dynamics of Influenza Virus Infection and Pathology
Authors: Saenz Roberto A. , Quinlivan Michelle , Elton Debra , MacRae Shona , Blunden Anthony S. , Mumford Jennifer A. , Daly Janet M. , Digard Paul , Cullinane Ann , Grenfell Bryan T. , McCauley John W. , Wood James L. N. , Gog Julia R.
Published: February 2010

A key question in pandemic influenza is the relative roles of innate immunity and target cell depletion in limiting primary infection and modulating pathology. Here, we model these interactions using detailed data from equine influenza virus infection, combining viral and immune (type I interferon) kinetics with estimates of cell depletion. The resulting dynamics indicate a powerful role for innate immunity in controlling the rapid peak in virus shedding. As a corollary, cells are much less depleted than suggested by a model of human influenza based only on virus-shedding data. We then explore how differences in the influence of viral proteins on interferon kinetics can account for the observed spectrum of virus shedding, immune response, and influenza pathology. In particular, induction of high levels of interferon (“cytokine storms”), coupled with evasion of its effects, could lead to severe pathology, as hypothesized for some fatal cases of influenza.
Rabies Virus Nucleoprotein Functions To Evade Activation of the RIG-I-Mediated Antiviral Response
Authors: Masatani Tatsunori , Ito Naoto , Shimizu Kenta , Ito Yuki , Nakagawa Keisuke , Sawaki Yoshiharu , Koyama Hiroyuki , Sugiyama Makoto
Published: February 2010

The rabies virus Ni-CE strain causes nonlethal infection in adult mice after intracerebral inoculation, whereas the parental Nishigahara (Ni) strain kills mice. We previously reported that the chimeric CE(NiN) strain with the N gene from the Ni strain in the genetic background of the Ni-CE strain kills adult mice, indicating that the N gene is related to the different pathogenicities of Ni and Ni-CE strains. In the present study, to obtain an insight into the mechanism by which the N gene determines viral pathogenicity, we compared the effects of Ni, Ni-CE, and CE(NiN) infections on host gene expressions using a human neuroblastoma cell line. Microarray analysis of these infected cells revealed that the expression levels of particular genes in Ni- and CE(NiN)-infected cells, including beta interferon (IFN-β) and chemokine genes (i.e., CXCL10 and CCL5) were lower than those in Ni-CE-infected cells. We also demonstrated that Ni-CE infection activated the interferon regulatory factor 3 (IRF-3)-dependent IFN-β promoter and induced IRF-3 nuclear translocation more efficiently than did Ni or CE(NiN) infection. Furthermore, we showed that Ni-CE infection, but not Ni or CE(NiN) infection, strongly activates the IRF-3 pathway through activation of RIG-I, which is known as a cellular sensor of virus infection. These findings indicate that the N protein of rabies virus (Ni strain) has a function to evade the activation of RIG-I. To our knowledge, this is the first report that the
Mononegavirales
N protein functions to evade induction of host IFN and chemokines.
Contribution of Vaccine-Induced Immunity toward either the HA or the NA Component of Influenza Viruses Limits Secondary Bacterial Complications
Authors: Huber Victor C. , Peltola Ville , Iverson Amy R. , McCullers Jonathan A.
Published: February 2010

Secondary bacterial infections contribute to morbidity and mortality from influenza. Vaccine effectiveness is typically assessed using prevention of influenza, not secondary infections, as an endpoint. We vaccinated mice with formalin-inactivated influenza virus vaccine preparations containing disparate HA and NA proteins and demonstrated an ability to induce the appropriate anti-HA and anti-NA immune profiles. Protection from both primary viral and secondary bacterial infection was demonstrated with vaccine-induced immunity directed toward either the HA or the NA. This finding suggests that immunity toward the NA component of the virion is desirable and should be considered in generation of influenza vaccines.
Some applications of polarography for investigation of equlibria in aqueous solutions of organic compounds
Authors: Zuman Petr
Published: February 2010

There are two possibilities how to follow equilibria of organic compounds established in aqueous solutions using polarography: for very fast reactions, information can be obtained from shifts of half-wave potentials. For slowly established equilibria, the changes in the limiting current are followed. In both cases variation of the half-wave potentials or limiting currents with concentration of a reactant, present in excess, is followed. The types of reactions, which had been followed in this way, are as follows: hydration–dehydration equilibria, additions of hydroxide ion to carbonyl and nitroso compounds, the role of slowly established acid–base equilibria involving C-acids; further also reactions involving the addition of ammonia, primary amines, hydroxylamine, and hydrazine to carbonyl compounds.
Examining the public refusal to consent to DNA biobanking: empirical data from a Swedish population-based study
Authors: Melas Philippe A , Sjöholm Louise K , Forsner Tord , Edhborg Maigun , Juth Niklas , Forsell Yvonne , Lavebratt Catharina
Published: February 2010

Objectives

To investigate empirically the motivations for not consenting to DNA biobanking in a Swedish population-based study and to discuss the implications.

Design

Structured questionnaires and semistructured interviews.

Setting

A longitudinal epidemiological project (PART) ongoing since 1998 in Stockholm, Sweden. The DNA-collection wave took place during 2006–7.

Participants

903 individuals completed the questionnaire (participation rate 36%) and 23 were interviewed. All individuals had participated in both non-genetic waves of the project, but refused to contribute saliva samples during the DNA-collection wave.

Main outcome measures

Motivations behind refusing to consent to DNA biobanking, with subsequent focus on participants' explanations regarding this unwillingness.

Results

Public refusal to consent to DNA biobanking, as revealed by the questionnaire, was mainly explained by a lack of personal relevance of DNA contribution and feelings of discomfort related to the DNA being used for purposes other than the respective study. Interviews of individuals representing the second motivation, revealed a significant mistrust of DNA biobank studies. The underlying beliefs and attitudes were associated with concerns about integrity, privacy, suspiciousness and insecurity. However, most interviewees were supportive of genetic research per se and interpreted their mistrust in the light of distressing environmental influences.

Conclusion

The results suggest a need for guidelines on benefit sharing, as well as trustworthy and stable measures to maintain privacy, as a means for increasing personal relevance and trust among potential participants in genetic research. Measures taken from biobanks seem insufficient in maintaining and increasing trust, suggesting that broader societal measures should be taken.
Normative consent and opt-out organ donation
Authors: Saunders Ben
Published: February 2010

One way of increasing the supply of organs available for transplant would be to switch to an opt-out system of donor registration. This is typically assumed to operate on the basis of presumed consent, but this faces the objection that not all of those who fail to opt out would actually consent to the use of their cadaveric organs. This paper defuses this objection, arguing that people's actual, explicit or implicit, consent to use their organs is not needed. It borrows David Estlund's notion of ‘normative consent’ from the justification of political authority and applies it to the case of organ donation. According to this idea, when it is wrong to withhold consent to something, the moral force of that lack of consent may be null and void. If it is wrong of a person to refuse to donate their cadaveric organs to others, then it may be that their actual consent is not needed. This supports an opt-out system, which provides protection for those who have genuine reasons to refuse donation, and spares the worries as to what the deceased would actually have wanted.
Post-recruitment confirmation of informed consent by SMS: Figure 1
Authors: Gulbrandsen Pål , Jensen Bård Fossli
Published: February 2010

Background

To allow patients to reflect about a decision to participate in a clinical trial, guidelines suggest a 24-h delay from when they are informed about the trial to when they give consent. In certain clinical settings, this is likely to hamper recruitment.

Method

After oral and written information about the trial has been given in person, the patient signs the declaration of consent knowing that they will be asked again after 24 h whether they confirm or regret the decision. This procedure can be done by SMS. The investigators must document the response. The procedure was tried in a study in which the doctors were randomly assigned to receive a clinical communication skills course, and encounters with patients were videotaped before and after the course.

Results

553 patients were approached, 530 (95.8%) gave initial consent, eight of these later regretted their consent.

Discussion

The low level of regrets suggests this is an acceptable procedure for patients.

Trial registration

The RCT was registered before initiation – registration # ISRCTN22153332.
Arsenical peripheral neuropathy: Table
Authors: Mathew Liberty , Vale Allister , Adcock Jane E
Published: February 2010

A 49-year-old white man returned urgently to the UK after spending 3 months in Goa. He had a several week history of vomiting, weight loss, a widespread desquamating skin rash, and symptoms and signs of a progressive painful sensorimotor neuropathy. He had a mild normocytic anaemia and lymphopenia. Nerve conduction studies revealed a severe predominantly axonal large fibre sensorimotor neuropathy, confirmed on subsequent sural nerve biopsy. Once he had left Goa most of his symptoms started to rapidly settle although the neuropathic symptoms remained severe. Arsenic poisoning was suspected. A spot urine arsenic concentration was 300 μg/l, confirming the diagnosis. He was treated with chelation therapy. Deliberate arsenic poisoning was highly likely.
ROTATING ELECTROMAGNETIC WAVES IN TOROID-SHAPED REGIONS
Authors: CHINOSI CLAUDIA , DELLA CROCE LUCIA , FUNARO DANIELE
Published: February 2010

Electromagnetic waves, solving the full set of Maxwell equations in vacuum, are numerically computed. These waves occupy a fixed bounded region of the three-dimensional space, topologically equivalent to a toroid. Thus, their fluid dynamics analogs are vortex rings. An analysis of the shape of the sections of the rings, depending on the angular speed of rotation and the major diameter, is carried out. Successively, spherical electromagnetic vortex rings of Hill's type are taken into consideration. For some interesting peculiar configurations, explicit numerical solutions are exhibited.