Geochemical Investigations of Ordinary Chondrites, Shergottites, and Hawaiian Basalts

Part I: Quantifying peak temperatures achieved during metamorphism is critical for understanding the thermal histories of ordinary chondrite parent asteroids. I performed two-pyroxene geothermometry, using QUILF95, on the same Type 6 chondrites for which peak temperatures were estimated using the plagioclase geothermometer. Pyroxenes record a narrow, overlapping range of temperatures in H6 (865-926°C), L6 (812-934°C), and LL6 (874-945°C) chondrites. Lower plagioclase temperature estimates may not reflect peak metamorphic temperatures because chondrule glass probably recrystallized to plagioclase prior to reaching the metamorphic peak. The average temperature for H, L, and LL chondrites (~900°C) is at least 50°C lower than peak temperatures used in current asteroid thermal evolution models, which may require minor adjustments. Part II: The light lithophile elements lithium, beryllium, and boron have been used successfully to indicate recycled crust or fluids derived from recycled crust in the source regions of island arc lavas. Radiogenic isotopes and other geochemistry of Mauna Kea lavas and Martian basalts (basaltic shergottites) suggest their source regions may contain a crustal component. The goal of this study is to determine whether Li, Be, and B indicate the presence of a crustal component in the source regions of Mauna Kea and Martian basalts and whether it was altered at low temperatures. Mauna Kea: Although several samples show effects of alteration, our results suggest Li (3.9±0.9 ppm) and Be (0.47±0.09 ppm) preserve mantle compositions. In contrast, highly variable B/K ratios (0.0002-0.008) and B/Be ratios (1-25) suggest post-magmatic alteration has destroyed the mantle B signature. When examined with depth, Li and Be abundances increase in the uppermost portion of the core, in late main shield and post-shield samples, and correspond to decreasing degrees of partial melting as the volcano moved off the plume’s center. Li and Be appear to be well mixed in the Hawaiian source region as evidenced by the lack of correlation between Li/Yb or Be/Nd ratios and Pb isotopes or Nb/Zr ratios, which were previously used to identify geochemically distinct Mauna Kea lava groups. Such mixing probably also accounts for the lack of any crustal signature when Li/Yb or Be/Nd are compared with O isotopes. These elements do not appear to vary on the timescale of Hawaiian shield development, possibly reflecting the efficiency with which these elements are homogenized in the mantle. Martian basalts: Although terrestrial alteration minerals (caliche) in Dhofar 019 apparently affected the primary Li and Be concentrations, the remaining basaltic shergottites contain Be (0.09-0.77 ppm) abundances similar to mid-ocean ridge basalts or ocean island basalts, whereas Li abundances (2.7-9.9 ppm) are slightly higher compared to these reservoirs. On diagrams of Li/Yb vs. Dy/Yb and K/Li vs. La/Yb, basaltic shergottites define trends similar to IAB, which are attributed to altered oceanic crust in the IAB source regions. However, the correlation between Li or Be and d18O for basaltic shergottites is weak, and d7Li values measured in two geochemically distinct basaltic shergottites, Zagami (+3.97‰) and EETA79001 (+4.37‰), are identical within error. Therefore, although the Martian assimilant appears to be enriched in Li and possibly Be, it either was not altered at low temperatures or the proportion of altered material in basaltic shergottite magmas is too small to be resolved using these crustal indicators

Comprehensive assessment of youth violence in five Caribbean countries: Gender and age differences

Differences in gender and age have been established in the context of crime, violence, and prevalence of risk and protective factors. These studies are often notable only in the Western Hemisphere. Despite growth in crime and violence in the Caribbean Community (CARICOM), relatively little understanding of violence in CARICOM member states exists. In light of these concerns, the major purposes of this study include: (1) comprehensively assessing the scope of the four behaviors (i.e., engagement, victimization, witness, and report) in relation to violence and youth’s perceptions of risk and protective factors in family and school domains, and (2) examining how they differ by youth’s gender and age. This study draws on assessment data on youth violence in five CARICOM Member States: Antigua and Barbuda, St. Kitts and Nevis, St. Lucia, Jamaica, and Trinidad and Tobago using a completed 51-item quantitative questionnaire from approximately 512 students. The results suggest that violence engagement, victimization, witness, and report significantly differed by gender and age. Male students were more likely to engage in violence, but less likely to report such violence to adults. Similarly, older students reported that they were more likely to engage in and witness violence. For risk and protective factors, female students reported significantly higher scores on domestic violence, whereas male students had higher scores on the access to drugs/weapons. Older students also tended to report higher levels of some school risk factors and lower levels of some protective factors in both family and school

A review of metrology in lithium-ion electrode coating processes

Lithium-ion battery electrode design and manufacture is a multi-faceted process where the link between underlying physical processes and manufacturing outputs is not yet fully understood. This is in part due to the many parameters and variables involved and the lack of complete data sets under different processing conditions. The slurry coating step has significant implications for electrode design and advanced metrology offers opportunities to improve understanding and control at this stage. Here, metrology options for slurry coating are reviewed as well as opportunities for in-line integration, discussing the benefits of combining advanced metrology to provide comprehensive characterisation, improve understanding and feed into predictive design models. There is a comprehensive range of metrology which needs little improvement to provide the relevant quantifiable measures during coating, with one exception of particle sizing, where more precise, in-line measurement would be beneficial. However, there is a lack of studies that bring together the latest advancements in electrode coating metrology which is crucial to understanding the interdependency of myriad processing and product parameters. This review highlights the need for a comprehensive metrological picture whose value would be much greater than the sum of its parts for the next generation of multiphysics and data-driven models

Isolating and Reconstructing Key Components of North Atlantic Ocean Variability From a Sclerochronological Spatial Network

This is the final version. Available from AGU via the DOI in this record.Our understanding of North Atlantic Ocean variability within the coupled climate system is limited by the brevity of instrumental records and a deficiency of absolutely dated marine proxies. Here we demonstrate that a spatial network of marine stable oxygen isotope series derived from molluscan sclerochronologies (δ18Oshell) can provide skillful annually resolved reconstructions of key components of North Atlantic Ocean variability with absolute dating precision. Analyses of the common δ18Oshell variability, using principal component analysis, highlight strong connections with tropical North Atlantic and subpolar gyre (SPG) sea surface temperatures and sea surface salinity in the North Atlantic Current (NAC) region. These analyses suggest that low-frequency variability is dominated by the tropical Atlantic signal while decadal variability is dominated by variability in the SPG and salinity transport in the NAC. Split calibration and verification statistics indicate that the composite series produced using the principal component analysis can provide skillful quantitative reconstructions of tropical North Atlantic and SPG sea surface temperatures and NAC sea surface salinities over the industrial period (1864–2000). The application of these techniques with extended individual δ18Oshell series provides powerful baseline records of past North Atlantic variability into the unobserved preindustrial period. Such records are essential for developing our understanding of natural climate variability in the North Atlantic Ocean and the role it plays in the wider climate system, especially on multidecadal to centennial time scales, potentially enabling reduction of uncertainties in future climate predictions

An integrated carbon and oxygen isotope approach to reconstructing past environmental variability in the northeast Atlantic Ocean

The combined influence of temperature and the isotopic composition of the seawater (δ18Ow) often precludes the use of oxygen isotope (δ18O) records, derived from marine carbonates, to reconstruct absolute seawater temperatures, without the application of an independent δ18Ow proxy. Here we investigate the application of carbon isotope records (δ13Cshell), derived from the long-lived marine bivalve Glycymeris glycymeris, as a proxy for δ18Ow variability. Our analyses indicate G. glycymeris δ13Cshell data derived from growth increments >20 years of age contain strong ontogenetic trends (−0.013‰ yr−1, R = 0.98, P < 0.001, N = 51). These analyses demonstrate that, coupled with the ontogenetic trends, 54% of the variability in G. glycymeris δ13Cshell records can be explained by a combination of the marine Suess effect and physical (salinity and riverine input) and biological processes (primary production). The application of these δ13Cshell data in conjunction with co-registered δ18Oshell and growth increment width series, each of which have been shown to be sensitive to seawater temperature and primary productivity respectively, can therefore provide new insights into past environmental variability and help constrain uncertainties on reconstructions of past seawater temperature variability

Studies on the antagonism by chloramphenicol of carbon tetrachloride-induced damage: Examination of mitochondrial protein synthesis

The damage induced in the mitochondria of rat liver during intoxication by carbon tetrachloride is prevented by the administration of chloramphenicol early in the intoxication. The possibility that the protective ability of chloramphenicol lies in the compound's ability to inhibit mitochondrial protein synthesis was eliminated by the failure of other inhibitors of mitochondrial protein synthesis, namely Tevenel, a chloramphenicol analog, and oxytetracycline, to prevent mitochondrial damage. Conversely, the optical isomer of chloramphenicol, which is not an inhibitor of mitochondrial protein synthesis, and does not possess antibiotic activity, does prevent mitochondrial damage during intoxication by CCl4. SKF 525A also preserves mitochondrial integrity, albeit not as well as chloramphenicol. Chloramphenicol, early in the course of intoxication, partially prevents the characteristic loss of protein synthesis after CCl4. It was concluded that the protective action of chloramphenicol could be due to either an interdiction of a destructive event triggered by CCl4, or to the preservation of the cellular repair processes being served by protein synthesis in the cytosol.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/21664/1/0000051.pd

Thermal history modeling of the H chondrite parent body

The cooling histories of individual meteorites can be empirically reconstructed by using ages from different radioisotopic chronometers with distinct closure temperatures. For a group of meteorites derived from a single parent body such data permit the reconstruction of the cooling history and properties of that body. Particularly suited are H chondrites because precise radiometric ages over a wide range of closure temperatures are available. A thermal evolution model for the H chondrite parent body is constructed by using all H chondrites for which at least three different radiometric ages are available. Several key parameters determining the thermal evolution of the H chondrite parent body and the unknown burial depths of the H chondrites are varied until an optimal fit is obtained. The fit is performed by an 'evolution algorithm'. Empirical data for eight samples are used for which radiometric ages are available for at least three different closure temperatures. A set of parameters for the H chondrite parent body is found that yields excellent agreement (within error bounds) between the thermal evolution model and empirical data of six of the examined eight chondrites. The new thermal model constrains the radius and formation time of the H chondrite parent body (possibly (6) Hebe), the initial burial depths of the individual H chondrites, the average surface temperature of the body, the average initial porosity of the material the body accreted from, and the initial 60Fe content of the H chondrite parent body.Comment: 16 pages, 7 figure

A Marfan syndrome‐like phenotype caused by a neocentromeric supernumerary ring chromosome 15

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/135625/1/ajmga38000.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/135625/2/ajmga38000_am.pd

Optimal searching behaviour generated intrinsically by the central pattern generator for locomotion.

Efficient searching for resources such as food by animals is key to their survival. It has been proposed that diverse animals from insects to sharks and humans adopt searching patterns that resemble a simple Lévy random walk, which is theoretically optimal for 'blind foragers' to locate sparse, patchy resources. To test if such patterns are generated intrinsically, or arise via environmental interactions, we tracked free-moving Drosophila larvae with (and without) blocked synaptic activity in the brain, suboesophageal ganglion (SOG) and sensory neurons. In brain-blocked larvae, we found that extended substrate exploration emerges as multi-scale movement paths similar to truncated Lévy walks. Strikingly, power-law exponents of brain/SOG/sensory-blocked larvae averaged 1.96, close to a theoretical optimum (µ ≅ 2.0) for locating sparse resources. Thus, efficient spatial exploration can emerge from autonomous patterns in neural activity. Our results provide the strongest evidence so far for the intrinsic generation of Lévy-like movement patterns

Outgassing of Ordinary Chondritic Material and Some of its Implications for the Chemistry of Asteroids, Planets, and Satellites

We used chemical equilibrium calculations to model thermal outgassing of ordinary chondritic material as a function of temperature, pressure, and bulk compositions and use our results to discuss outgassing on asteroids and the early Earth. The calculations include ~1,000 solids and gases of the elements Al, C, Ca, Cl, Co, Cr, F, Fe, H, K, Mg, Mn, N, Na, Ni, O, P, S, Si, and Ti. The major outgassed volatiles from ordinary chondritic material are CH4, H2, H2O, N2, and NH3(the latter at conditions where hydrous minerals form). Contrary to widely held assumptions, CO is never the major C-bearing gas during ordinary chondrite metamorphism. The calculated oxygen fugacity (partial pressure) of ordinary chondritic material is close to that of the quartz-fayalite-iron (QFI) buffer. Our results are insensitive to variable total pressure, variable volatile element abundances, and kinetic inhibition of C and N dissolution in Fe metal. Our results predict that Earth's early atmosphere contained CH4, H2, H2O, N2, and NH3; similar to that used in Miller-Urey synthesis of organic compounds.Comment: 72 pages, 17 figures, 3 tables; submitted to Icaru