Rifts in Spreading Wax Layers

We report experimental results on the rift formation between two freezing wax plates. The plates were pulled apart with constant velocity, while floating on the melt, in a way akin to the tectonic plates of the earth's crust. At slow spreading rates, a rift, initially perpendicular to the spreading direction, was found to be stable, while above a critical spreading rate a "spiky" rift with fracture zones almost parallel to the spreading direction developed. At yet higher spreading rates a second transition from the spiky rift to a zig-zag pattern occurred. In this regime the rift can be characterized by a single angle which was found to be dependent on the spreading rate. We show that the oblique spreading angles agree with a simple geometrical model. The coarsening of the zig-zag pattern over time and the three-dimensional structure of the solidified crust are also discussed.Comment: 4 pages, Postscript fil

Identifying a sufficient core group for trachoma transmission.

BackgroundIn many infectious diseases, a core group of individuals plays a disproportionate role in transmission. If these individuals were effectively prevented from transmitting infection, for example with a perfect vaccine, then the disease would disappear in the remainder of the community. No vaccine has yet proven effective against the ocular strains of chlamydia that cause trachoma. However, repeated treatment with oral azithromycin may be able to prevent individuals from effectively transmitting trachoma.Methodology/principal findingsHere we assess several methods for identifying a core group for trachoma, assuming varying degrees of knowledge about the transmission process. We determine the minimal core group from a completely specified model, fitted to results from a large Ethiopian trial. We compare this benchmark to a core group that could actually be identified from information available to trachoma programs. For example, determined from the rate of return of infection in a community after mass treatments, or from the equilibrium prevalence of infection.Conclusions/significanceSufficient groups are relatively easy for programs to identify, but will likely be larger than the theoretical minimum

Bodyspace at the pub: sexual orientations and organizational space

In this article we argue that sexuality is not only an undercurrent of service environments, but is integral to the way that these workspaces are experienced and negotiated. Through drawing on Sara Ahmed’s (2006a) ‘orientation’ thesis, we develop a concept of ‘bodyspace’ to suggest that individuals understand, shape and make meaning of work spaces through complex sexually-orientated negotiations. Presenting analysis from a study of UK pubs, we explore bodyspace in the lived experience of workplace sexuality through three elements of orientation: background; bodily dwelling; and lines of directionality. Our findings show how organizational spaces afford or mitigate possibilities for particular bodies, which simultaneously shape expectations and experiences of sexuality at work. Bodyspace therefore provides one way of exposing the connection between sexual ‘orientation’ and the lived experience of service sector work

An Experimental Overview of Results Presented at SQM 2006

I have been asked to give an critical overview on the experimental results shown in the conference with a emphasis of what has been learned and the challenges that are ahead in trying to understand the physics of the strongly interacting quark-gluon plasma. I will not try to summarize all of the results presented, rather I will concentrate primarily on RHIC data from this conference. Throughout this summary, I will periodically review some of the previous results for those not familiar with the present state of the field.Comment: 15 pages, 12 Figure

Recent Results on Strangeness Production at RHIC

Due to its large acceptance, the STAR experiment has acquired a wealth of data on strangeness production for a variety of collisions systems and energies, from p+p to Au+Au. By using the yields and spectra, we address the evolution of the bulk system, including strangeness enhancement and the flavour dependence of radial and elliptic flow. Utilising the fact that we can identify strange baryons and mesons, we investigate different hadronization mechanisms in the intermediate and high p$_{T}$ regions. The ratios of the particle yields, measured to high p$_{T}$, are used to further investigate the range and applicability of the previously reported anomalous baryon production. We also study two-particle azimuthal correlations of identified particles in order to investigate any flavour dependence of jet fragmentation in the available p$_{T}$ range. Data was presented for a number of different collision systems and energies.Comment: Proceedings of SQM'06 Conference, LA, 2006 (submitted to J. Phys. G

Enhanced data analysis for the VZMS: Conceptual model design and initial application for the Vadose Zone Monitoring System (VZMS), McClellan AFB. 1998 semi-annual report

The VZMS project at McClellan AFB involves both vadose zone data collection as well as enhanced data analysis. The purpose of enhanced data analysis is to develop conceptual models to carry out model validation and evaluation, as well as sensitivity and predictive modeling studies. Enhanced data analysis consists primarily of T2VOC forward simulations and ITOUGH2 inverse modeling. The methodology the authors employ in the VZMS project involves developing a conceptual model and iteratively updating it based on the agreement between model results and VZMS data. They demonstrate the development of an initial T2VOC conceptual model for the S-7 site based on data from instrument cluster VZMS-B. Lithologic data from the drilling logs along with empirical relations for estimating permeability and sediment moisture retention characteristics are used to define the layering of four different sediment types. The authors adjusted the layering of the sediments manually until the sediment moisture content profile from the T2VOC simulation of the gravity-capillary equilibrium agreed well with observed neutron probe data. Using this updated conceptual model, they performed inverse modeling using ITOUGH2 to find bet-fit absolute permeability values based on the minimization of differences between simulated and actual soil-gas pressure measurements

Sequestration of CO2 in the Altmark Natural Gas Field, Germany: Mobility Control to Extend Enhanced Gas Recovery

We are investigating the technical feasibility of injecting CO2 for carbon sequestration with enhanced gas recovery (CSEGR) in the depleted Altmark natural gas reservoir, Germany. Our approach is numerical simulation using TOUGH2/EOS7C. Our earlier simulation studies have shown early CO2 breakthrough due to fast-flow through the high-permeability sand layers. In order to extend the period of enhanced CH4 recovery, we propose the preinjection of gelling fluids for the purpose of limiting the mobility of injected CO2 and thereby improving CO2 sweep and delaying CO2 breakthrough. We have implemented a simple gel model into EOS7C and simulated gel injection followed by CSEGR.Preliminary simulations to date show minimal improvements in CSEGR with breakthrough times delayed by only a few months to a year. While mobility control using pre-injected gelling fluids appears to be a promising strategy in controlling early breakthrough, more work is needed to design and simulate an effective procedure

Partonic effects on anisotropic flows at RHIC

We report recent results from a multiphase transport (AMPT) model on the azimuthal anisotropies of particle momentum distributions in heavy ion collisions at the Relativistic Heavy Ion Collider. These include higher-order anisotropic flows and their scaling, the rapidity dependence of anisotropic flows, and the elliptic flow of charm quarks.Comment: 7 pages, 5 figures, talk given at "Hot Quarks 2004", July 18-24, 2004, Taos Valley, NM, US