Basal-plane metallography of deformed pyrolytic carbon

Cleavage technique is recommended over the normal polishing technique in preparing pyrolytic carbon for metallographic examination of basal-plane surfaces. After careful removal of torn basal-plane fragments and other cleavage debris with cellulose tape, the true structure is clearly revealed

Automatic sample rotator for metallographic polishing

Simple, inexpensive device can be attached to most metallographic sample polishing tables. It provides a suitable surface finish for microscopic examination or photography of surface details of the samples

Assessing the ability of the 14C projection-age method to constrain the circulation of the past in a 3-D ocean model

Radiocarbon differences between benthic and planktonic foraminifera (B-P ages) and radiocarbon projection ages are both used to determine changes of the past ocean circulation rate. A global 3-D ocean circulation model with a constant modern ocean circulation is used to study which method is less influenced by atmospheric Δ14C variations. Three factors cause uncertainties: first, the long equilibration time of the ocean after atmospheric Δ14C changes; second, different mixing processes in the ocean, which cause an ocean response of smaller amplitude than the atmospheric forcing; and third, the unknown source region and corresponding initial surface 14C reservoir age of subsurface waters. The model suggests that B-P ages and projection ages have lower uncertainties the closer they are to deepwater formation zones. In the North Atlantic the B-P age method is less influenced by atmospheric Δ14C variations than the projection-age method. Projections ages vary less in the Pacific as long as atmospheric Δ14C decreases linearly. A more irregular atmospheric Δ14C evolution leads to age variations of similar magnitude with both methods. On the basis of the model experiment, we suggest a potential improvement of the projection-age method

A search for massive neutral bosons in orthopositronium decay

We have searched for an exotic decay of orthopositronium into a single photon and a short-lived neutral boson in the hitherto unexplored mass region above 900 ${\rm keV}/{\it c}^{2}$, by noting that this decay is one of few remaining candidates which could explain the discrepancy of the orthopositronium decay-rate. A high-resolution measurement of the associated photon energy spectrum was carried out with a germanium detector to search for a sharp peak from this two-body decay. Our negative result provides the upper-limits of\mbox{ }$2.0 \times 10^{-4}$ on the branching ratio of such a decay in the mass region from 847 to 1013 ${\rm keV}/{\it c}^{2}$, and excludes the possibility of this decay mode explaining the discrepancy in the orthopositronium decay-rate.Comment: a LaTeX file (text 7 pages) and a uuencoded gz-compressed PostScript file (text 7 pages + figures 4 pages

Composite Skyrme Model with Vector Mesons

We study the composite Skyrme model, proposed by Cheung and G\"{u}rsey, introducing vector mesons in a chiral Lagrangian. We calculate the static properties of baryons and compare with results obtained from models without vector mesons.Comment: LaTeX, 9 pages, 3 figures, to be published in Phys. Rev.

Two-loop corrections to the decay rate of parapositronium

Order $\alpha^2$ corrections to the decay rate of parapositronium are calculated. A QED scattering calculation of the amplitude for electron-positron annihilation into two photons at threshold is combined with the technique of effective field theory to determine an NRQED Hamiltonian, which is then used in a bound state calculation to determine the decay rate. Our result for the two-loop correction is $5.1243(33)$ in units of $(\alpha/\pi)^2$ times the lowest order rate. This is consistent with but more precise than the result $5.1(3)$ of a previous calculation.Comment: 26 pages, 7 figure

Reducing Animal Numbers in a Contact Sentinel Program

Rodent health surveillance using sentinel animals is a critical part of the preventative health program for most laboratory rodent facilities. Introduction of animals through a quarantine area is generally one of the highest biosecurity risk areas in a rodent housing facility. Adequate health surveillance of animals during the quarantine period is critical to prevent introducing unwanted microorganisms

Pricing Bodies: A Feminist New Materialist Approach to the Relations Between the Economic and Socio-Cultural

Arguments that the economic and socio-cultural should be understood as relational and intertwined, and that price involves a reciprocal relationship between the economic and socio-cultural, are increasingly prevalent in the social sciences. I develop these notions of relationality and reciprocation through a feminist new materialist perspective, which emphasises the entanglement of and intra-action between what might usually be seen as independent and autonomous entities. To do this, I focus on a range of recent body-image initiatives, led by government, corporate and non-profit organisations, which aim to improve girls’ and young women’s levels of confidence and self-esteem. I explore how feminist theory tends to see such initiatives in terms of the expansion of the economic sphere into the socio-cultural, which involves a tainting or contamination of embodiment and feeling. Rather than dispute these arguments, I take seriously theories and practices from cultural economy that see the economic and socio-cultural as co-constitutive. I augment these ideas with a feminist new materialist approach and argue that the economic and socio-cultural are in intra-active relations: they do not precede or exist apart from each other. In doing so, I consider how body-image initiatives can be understood as phenomena produced through these entangled intra-active relations, and offer an understanding of pricing as a simultaneously socio-cultural and economic process, where value and values become. I also raise questions regarding how, ethically and politically, boundary making and unmaking can be conceived, and how despite being in entangled relations, asymmetries between economic and socio-cultural relations may be approached

The Single Photon Annihilation Contributions to the Positronium Hyperfine Splitting to Order meα6m_e\alpha^6

The single photon annihilation contributions for the positronium ground state hyperfine splitting are calculated analytically to order $m_e\alpha^6$ using NRQED. Based on intuitive physical arguments the same result can also be determined by a trivial calculation using results from existing literature. Our result completes the hyperfine splitting calculation to order $m_e\alpha^6$. We compare the theoretical prediction with the most recent experimental measurement.Comment: 8 pages, latex, two eps figures include