A Geochemical Characterization of Putative Biosignatures in Subseafloor Basalts

The discoveries of tubular alteration features of potential biological origin in subseafloor basalt glasses, ophiolites, and ancient greenstones has important implications for increasing our understanding of global biogeochemical cycling in hard-rock systems and the evolution of life on Earth, and for exploring other planets for signs of life. Given the technological challenges in accessing the modern subseafloor and the possibility that it could take thousands of years to form these features, at this point it is not possible to observe their formation in-situ, nor have they been successfully modeled in the lab. Thus, we must infer the formation and preservation mechanisms of these putative biosignatures from physical and chemical clues. We have used a number of micro-analytical techniques to geochemically characterize these features at the submicron scale. Using focused ion beam milling we prepared ultra-thin cross-sections of the tubules, which enabled high-resolution imaging and chemical analyses by transmission electron microscopy and electron-dispersive spectroscopy. These analyses revealed leached rims around the tubule margins, and partially crystalline Fe-bearing phyllosilicates infilling the tubules. In addition, we combined four different high-resolution synchrotron-based techniques, including X-ray fluorescence microprobe mapping, micro-diffraction, and absorption spectroscopy to determine the distribution and speciation of key major and trace elements. These studies revealed consistent patterns of Ca, Mg, Ti, Fe, Mn, S, and P distributions, metal oxidation, and authigenic precipitation of secondary phases, as well as identified possible biominerals and organic material. Put together, these results have provided insight into the processes involved in tubular alteration and mineralization. The formation mechanism involves initial incongruent dissolution of the glass potentially accompanied by the authigenic precipitation of biominerals, specifically Fe-oxides and sulfate. Successive stages of fluid flow then infill the tubules with a variety of Feand Ti-rich minerals, with concomitant partial to complete oxidation of the redox active elements. The consistency of these results across a 100Ma suite of subseafloor samples and one ophiolite sample implies that the alteration and mineralization patterns are consistent spatially and temporally. These results also add significant evidence to the argument for the biological formation of the tubules by revealing potential signs of microbial geochemical processing

A gradient approach to localization of deformation. I. Hyperelastic materials

By utilizing methods recently developed in the theory of fluid interfaces, we provide a new framework for considering the localization of deformation and illustrate it for the case of hyperelastic materials. The approach overcomes one of the major shortcomings in constitutive equations for solids admitting localization of deformation at finite strains, i.e. their inability to provide physically acceptable solutions to boundary value problems in the post-localization range due to loss of ellipticity of the governing equations. Specifically, strain-induced localized deformation patterns are accounted for by adding a second deformation gradient-dependent term to the expression for the strain energy density. The modified strain energy function leads to equilibrium equations which remain always elliptic. Explicit solutions of these equations can be found for certain classes of deformations. They suggest not only the direction but also the width of the deformation bands providing for the first time a predictive unifying method for the study of pre- and post-localization behavior. The results derived here are a three-dimensional extension of certain one-dimensional findings reported earlier by the second author for the problem of simple shear.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/42674/1/10659_2004_Article_BF00040814.pd

Muon capture by 3He nuclei followed by proton and deuteron production

The paper describes an experiment aimed at studying muon capture by ${}^{3}\mathrm{He}$ nuclei in pure ${}^{3}\mathrm{He}$ and $\mathrm{D}_2 + {}^{3}\mathrm{He}$ mixtures at various densities. Energy distributions of protons and deuterons produced via $\mu^-+{}^{3}\mathrm{He}\to p+n+n + \nu_{\mu }$ and $\mu^-+{}^{3} \mathrm{He} \to d+n + \nu_{\mu}$ are measured for the energy intervals $10 - 49$ MeV and $13 - 31$ MeV, respectively. Muon capture rates, $\lambda_\mathrm{cap}^p (\Delta E_p)$ and $\lambda_\mathrm{cap}^d (\Delta E_d)$ are obtained using two different analysis methods. The least--squares methods gives $\lambda_\mathrm{cap}^p = (36.7\pm 1.2) {s}^{- 1}$, $\lambda_\mathrm{cap}^d = (21.3 \pm 1.6) {s}^{- 1}$. The Bayes theorem gives $\lambda_\mathrm{cap}^p = (36.8 \pm 0.8) {s}^{- 1}$, $\lambda_\mathrm{cap}^d = (21.9 \pm 0.6) {s}^{- 1}$. The experimental differential capture rates, $d\lambda_\mathrm{cap}^p (E_p) / dE_p$ and $d\lambda_\mathrm{cap}^d (E_d) / dE_d$, are compared with theoretical calculations performed using the plane--wave impulse approximation (PWIA) with the realistic NN interaction Bonn B potential. Extrapolation to the full energy range yields total proton and deuteron capture rates in good agreement with former results.Comment: 17 pages, 13 figures, accepted for publication in PR

Degradation and healing in a generalized neo-Hookean solid due to infusion of a fluid

The mechanical response and load bearing capacity of high performance polymer composites changes due to diffusion of a fluid, temperature, oxidation or the extent of the deformation. Hence, there is a need to study the response of bodies under such degradation mechanisms. In this paper, we study the effect of degradation and healing due to the diffusion of a fluid on the response of a solid which prior to the diffusion can be described by the generalized neo-Hookean model. We show that a generalized neo-Hookean solid - which behaves like an elastic body (i.e., it does not produce entropy) within a purely mechanical context - creeps and stress relaxes when infused with a fluid and behaves like a body whose material properties are time dependent. We specifically investigate the torsion of a generalized neo-Hookean circular cylindrical annulus infused with a fluid. The equations of equilibrium for a generalized neo-Hookean solid are solved together with the convection-diffusion equation for the fluid concentration. Different boundary conditions for the fluid concentration are also considered. We also solve the problem for the case when the diffusivity of the fluid depends on the deformation of the generalized neo-Hookean solid.Comment: 24 pages, 10 figures, submitted to Mechanics of Time-dependent Material

The first decade of web-based sports injury surveillance: Descriptive epidemiology of injuries in US high school girls’ softball (2005–2006 through 2013–2014) and National Collegiate Athletic Association women’s softball (2004–2005 through 2013–2014)

Context: The advent of Web-based sports injury surveillance via programs such as the High School Reporting Information Online system and the National Collegiate Athletic Association Injury Surveillance Program has aided the acquisition of girls’ and women’s softball injury data. Objective: To describe the epidemiology of injuries sustained in high school girls’ softball in the 2005–2006 through 2013–2014 academic years and collegiate women’s softball in the 2004–2005 through 2013–2014 academic years using Web-based sports injury surveillance. Design: Descriptive epidemiology study. Setting: Online injury surveillance from softball teams in high school girls (annual average ¼ 100) and collegiate women (annual average ¼ 41). Patients or Other Participants: Girls’ or women’s softball players who participated in practices and competitions during the 2005–2006 through 2013–2014 academic years in high school and the 2004–2005 through 2013–2014 academic years in college. Main Outcome Measure(s): Athletic trainers collected time-loss injury and exposure data. Injury rates per 1000 athlete-exposures (AEs) were calculated. Injury rate ratios (IRRs) with 95% confidence intervals (CIs) compared injury rates by competition level, school size or division, event type, and time in season. Results: The High School Reporting Information Online system documented 1357 time-loss injuries during 1 173 722 AEs; the National Collegiate Athletic Association Injury Surveillance Program documented 1848 time-loss injuries during 579 553 AEs. The injury rate was higher in college than in high school (3.19 versus 1.16/1000 AEs; IRR ¼ 2.76; 95% CI ¼ 2.57, 2.96). The competition injury rate was higher than the practice injury rate in high school (IRR ¼ 2.02; 95% CI ¼ 1.82, 2.25) and in college (IRR ¼ 1.39; 95% CI ¼ 1.27, 1.52). Softball players at both levels sustained a variety of injuries, with the most common being ankle sprains and concussions. Many injuries also occurred while fielding or running bases. Conclusions: Injury rates were greater in collegiate versus high school softball and in competitions versus practices. These findings highlight the need for injury-prevention interventions, including strength-training and prevention programs to reduce ankle sprains and provide protection for batters from pitches and fielders from batted balls

The first decade of web-based sports injury surveillance: Descriptive epidemiology of injuries in US high school boys’ baseball (2005–2006 through 2013–2014) and National Collegiate Athletic Association men’s baseball (2004–2005 through 2013–2014)

Context: The advent of Web-based sports injury surveillance via programs such as the High School Reporting Information Online system and the National Collegiate Athletic Association Injury Surveillance Program has aided the acquisition of boys’ and men’s baseball injury data. Objective: To describe the epidemiology of injuries sustained in high school boys’ baseball in the 2005–2006 through 2013–2014 academic years and collegiate men’s baseball in the 2004–2005 through 2013–2014 academic years using Web-based sports injury surveillance. Design: Descriptive epidemiology study. Setting: Online injury surveillance from baseball teams in high school boys (annual average ¼ 100) and collegiate men (annual average ¼ 34). Patients or Other Participants: Boys’ or men’s baseball players who participated in practices and competitions during the 2005–2006 through 2013–2014 academic years in high school or the 2004–2005 through 2013–2014 academic years in college, respectively. Main Outcome Measure(s): Athletic trainers collected time-loss injury and exposure data. Injury rates per 1000 athlete-exposures (AEs) were calculated. Injury rate ratios (IRRs) with 95% confidence intervals (CIs) compared injury rates by schoolsize or division, time in season, event type, and competition level. Results: The High School Reporting Information Online system documented 1537 time-loss injuries during 1 573 257 AEs; the National Collegiate Athletic Association Injury Surveillance Program documented 2574 time-loss injuries during 804 737 AEs. The injury rate was higher in college than in high school (3.20 versus 0.98/1000 AEs; IRR ¼ 3.27; 95% CI ¼ 3.07, 3.49). The competition injury rate was higher than the practice injury rate in high school (IRR ¼ 2.27; 95% CI ¼ 2.05, 2.51) and college (IRR ¼ 2.32; 95% CI ¼ 2.15, 2.51). Baseball players at the high school and collegiate levels sustained a variety of injuries across the body, with the most common injuries reported to the upper extremity. Many injuries also occurred while fielding or pitching. Conclusions: Injury rates were greater in collegiate versus high school baseball and in competition versus practice. These findings highlight the need for injury-prevention interventions focused on reducing the incidence of upper extremity injuries and protecting batters from pitches and fielders from batted balls

The effectiveness of styrene-maleic acid (SMA) copolymers for solubilisation of integral membrane proteins from SMA-accessible and SMA-resistant membranes

Solubilisation of biological lipid bilayer membranes for analysis of their protein complement has traditionally been carried out using detergents, but there is increasing interest in the use of amphiphilic copolymers such as styrene maleic acid (SMA) for the solubilisation, purification and characterisation of integral membrane proteins in the form of protein/lipid nanodiscs. Here we survey the effectiveness of various commercially-available formulations of the SMA copolymer in solubilising Rhodobacter sphaeroides reaction centres (RCs) from photosynthetic membranes. We find that formulations of SMA with a 2:1 or 3:1 ratio of styrene to maleic acid are almost as effective as detergent in solubilising RCs, with the best solubilisation by short chain variants ( < 30 kDa weight average molecular weight). The effectiveness of 10 kDa 2:1 and 3:1 formulations of SMA to solubilise RCs gradually declined when genetically-encoded coiled-coil bundles were used to artificially tether normally monomeric RCs into dimeric, trimeric and tetrameric multimers. The ability of SMA to solubilise reaction centre-light harvesting 1 (RC-LH1) complexes from densely packed and highly ordered photosynthetic membranes was uniformly low, but could be increased through a variety of treatments to increase the lipid:protein ratio. However, proteins isolated from such membranes comprised clusters of complexes in small membrane patches rather than individual proteins. We conclude that short-chain 2:1 and 3:1 formulations of SMA are the most effective in solubilising integral membrane proteins, but that solubilisation efficiencies are strongly influenced by the size of the target protein and the density of packing of proteins in the membrane

Determination of alphaS from Hadronic Event Shapes in e+e- Annihilation at 192 < sqrt(s) < 208 GeV

Results are presented from a study of the structure of high energy hadronic events recorded by the L3 detector at sqrt(s)>192 GeV. The distributions of several event shape variables are compared to resummed O(alphaS^2) QCD calculations. We determine the strong coupling constant at three average centre-of-mass energies: 194.4, 200.2 and 206.2 GeV. These measurements, combined with previous L3 measurements at lower energies, demonstrate the running of alphaS as expected in QCD and yield alphaS(mZ) = 0.1227 +- 0.0012 +- 0.0058, where the first uncertainty is experimental and the second is theoretical

Quasistatic delamination of sandwich-like Kirchhoff-Love plates

A quasistatic rate-independent adhesive delamination problem of laminated plates with a finite thickness is considered. By letting the thickness of the plates go to zero, a rate-independent delamination model for a laminated Kirchhoff-Love plate is obtained as limit of these quasistatic processes. The same dimension reduction procedure is eventually applied to processes which are sensitive to delamination modes, namely opening vs. shearing is distinguishe