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

An Expansion Term In Hamilton's Equations

For any given spacetime the choice of time coordinate is undetermined. A particular choice is the absolute time associated with a preferred vector field. Using the absolute time Hamilton's equations are $- (\delta H_{c})/(\delta q)=\dot{\pi}+\Theta\pi,$+ (\delta H_{c})/(\delta \pi)=\dot{q}$, where$\Theta = V^{a}_{.;a}$is the expansion of the vector field. Thus there is a hitherto unnoticed term in the expansion of the preferred vector field. Hamilton's equations can be used to describe fluid motion. In this case the absolute time is the time associated with the fluid's co-moving vector. As measured by this absolute time the expansion term is present. Similarly in cosmology, each observer has a co-moving vector and Hamilton's equations again have an expansion term. It is necessary to include the expansion term to quantize systems such as the above by the canonical method of replacing Dirac brackets by commutators. Hamilton's equations in this form do not have a corresponding sympletic form. Replacing the expansion by a particle number$N\equiv exp(-\int\Theta d \ta)$and introducing the particle numbers conjugate momentum$\pi^{N}$the standard sympletic form can be recovered with two extra fields N and$\pi^N$. Briefly the possibility of a non-standard sympletic form and the further possibility of there being a non-zero Finsler curvature corresponding to this are looked at.Comment: 10 page

The role of ocean cooling in setting glacial southern source bottom water salinity

At the Last Glacial Maximum (LGM), the salinity contrast between northern source deep water and southern source bottom water was reversed with respect to the contrast today. Additionally, Glacial Southern Source Bottom Water (GSSBW) was saltier than Antarctic Bottom Water (AABW), over and above the difference implied by the mean sea level change. This study examines to what extent cold temperatures, through their effect on ice formation and melting, could have caused these differences. Computational sensitivity experiments using a coupled ice shelf cavity–sea ice–ocean model are performed in a Weddell Sea domain, as a representative case study for bottom water formation originating from Antarctic continental shelves. Ocean temperatures at the domain open boundaries are systematically lowered to determine the sensitivity of Weddell Sea water mass properties to a range of cool ocean temperatures. The steady state salinities differ between experiments due to temperature-induced responses of ice shelf and sea ice melting and freezing, evaporation and open boundary fluxes. The results of the experiments indicate that reduced ocean temperature can explain up to 30% of the salinity difference between GSSBW and AABW, primarily due to decreased ice shelf melting. The smallest and most exposed ice shelves, which abut narrow continental shelves, have the greatest sensitivity to the ocean temperature changes, suggesting that at the LGM there could have been a shift in geographical site dominance in bottom water formation. More sea ice is formed and exported in the cold ocean experiments, but the effect of this on salinity is negated by an equal magnitude reduction in evaporation

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

Pedagogical devices as children’s social care levers: A study of social care workers’ attitudes towards boarding schools to care for and educate children in need

It has been proposed that boarding schools in England can be used to provide a stable education and care environment for vulnerable children in need, and the government is expanding their use. However, for vulnerable children to be placed in boarding schools, social workers will need to be willing to contemplate boarding as a viable care option. In this study we interviewed N = 21 social care practitioners including directors, senior and middle managers, frontline social workers, social worker‐academics and family support workers who work with vulnerable children. Using thematic analysis of the transcribed interviews, seven major themes identified a range of issues and concerns held by social care workers about placing vulnerable children in boarding schools. We present these themes and consider the issues that will have to be addressed prior to changes in policy and practice. The study concludes that many of those within the social work profession are unlikely to consider boarding as an intervention for children in need. Further research in this area is a matter of urgency

Search for an exotic three-body decay of orthopositronium

We report on a direct search for a three-body decay of the orthopositronium into a photon and two penetrating particles, o-Ps -> gamma + X1 + X2. The existence of this decay could explain the discrepancy between the measured and the predicted values of the orthopositronium decay rate. From the analysis of the collected data a single candidate event is found, consistent with the expected background. This allows to set an upper limit on the branching ratio < 4.4 \times 10^{-5} (at the 90% confidence level), for the photon energy in the range from 40 keV < E_gamma< 400 keV and for mass values in the kinematical range 0 gamma + X1 + X2 decay mode as the origin of the discrepancy.Comment: 9 pages, 3 figure

Remarks on the Collective Quantization of the SU(2) Skyrme Model

We point out the question of ordering momentum operator in the canonical \break quantization of the SU(2) Skyrme Model. Thus, we suggest a new definition for the momentum operator that may solve the infrared problem that appears when we try to minimize the Quantum Hamiltonian.Comment: 8 pages, plain tex, IF/UFRJ/9