Transition from Baryon- to Meson-Dominated Freeze Out -- Early Decoupling around 30 A GeV?

The recently discovered sharp peak in the excitation function of the K+/pi+ ratio around 30 A GeV in relativistic heavy-ion collisions is discussed in the framework of the Statistical Model. In this model, the freeze-out of an ideal hadron gas changes from a situation where baryons dominate to one with mainly mesons. This transition occurs at a temperature T = 140 MeV and baryon chemical potential mu(B) = 410 MeV corresponding to an energy of sqrt(s) = 8.2 GeV. The calculated maximum in the K+/pi+ ratio is, however, much less pronounced than the one observed by the NA49 Collaboration. The smooth increase of the K-/pi- ratio with incident energy and the shape of the excitation functions of the Lambda/pi+, Xi-/pi+ and Omega/pi ratios all exhibiting maxima at different incident energies, is consistent with the presently available experimental data. The measured K+/pi+ ratio exceeds the calculated one just at the incident energy when the freeze-out condition is changing. We speculate that at this point freeze-out might occur in a modified way. We discuss a scenario of an early freeze-out which indeed increases K+/pi+ ratio while most other particle ratios remain essentially unchanged. Such an early freeze-out is supported by results from HBT studies.Comment: 8 pages, 5 figures, SQM2006 conference, Los Angeles, March 200

Statistical-Thermal Model Calculations using THERMUS

Selected results obtained using THERMUS, a newly-developed statistical-thermal model analysis package, are presented.Comment: Contributed to 8th International Conference on Strangeness in Quark Matter, Cape Town, South Africa, 15-20 September 200

Windsurfing : an extreme form of material and embodied interaction?

This paper makes reference to the development of water based board sports in the world of adventure or action games. With a specific focus on windsurfing, we use Parlebas (1999) and Warnier's (2001) theoretical interests in the praxaeology of physical learning as well as Mauss' (1935) work on techniques of the body. We also consider the implications of Csikzentimihalyi's notion of flow (1975). We argue that windsurfing equipment should not merely be seen as protection but rather as status objects through which extreme lifestyles are embodied and embodying

Examining Undergraduate College Students’ Experiences Participating in Longitudinal Qualitative Research

While many researchers describe the potential benefits to individuals if they opt to participate in qualitative research, it is not always feasible to empirically examine how engaging in a study influence the participants. Acknowledging this gap, we conducted a descriptive qualitative study to explore how 67 low-income students described their experiences as participants in a larger longitudinal qualitative research project that involved regularly submitting video diaries and participating in interviews over the course of three years. Overall, participants characterized their experiences as positive and highlighted unanticipated benefits of the project. Although many individuals were drawn to the project for the compensation, they found that regularly engaging in reflection with the support of a researcher they trusted to be beneficial. Participants often described their interviews as cathartic and as a place where they could make sense of their experiences in and outside of college. Opportunities for sustained reflection also helped participants increase their self-awareness. Additionally, participants described their videos as material evidence of their growth and development over time and indicated that this longitudinal project helped them develop their communication and time management skills

Centrality Dependence of Thermal Parameters Deduced from Hadron Multiplicities in Au + Au Collisions at sqrt{s_{NN}} = 130 GeV

We analyse the centrality dependence of thermal parameters deduced from hadron m ultiplicities in Au + Au collisions at $\sqrt{s_{NN}} = 130 GeV$. While the chemical freeze-out temperature and chemical potentials are found to be roughly centrality-independent, the strangeness saturation factor $\gamma_S$ increases with participant number towards unity, supporting the assumption of equilibrium freeze-out conditions in central collisions