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1.
Phys Rev Lett ; 102(18): 182501, 2009 May 08.
Artigo em Inglês | MEDLINE | ID: mdl-19518864

RESUMO

The K0 meson production by pi(-) mesons of 1.15 GeV/c momentum on C, Al, Cu, Sn, and Pb nuclear targets was measured with the FOPI spectrometer at the Schwer-Ionen-Synchrotron accelerator of GSI. Inclusive production cross sections and the momentum distributions of K0 mesons are compared to scaled elementary production cross sections and to predictions of theoretical models describing the in-medium production of kaons. The data represent a new reference for those models, which are widely used for interpretation of the strangeness production in heavy-ion collisions. The presented results demonstrate the sensitivity of the kaon production to the reaction amplitudes inside nuclei and point to the existence of a repulsive KN potential of 20+/-5 MeV at normal nuclear matter density.

2.
Phys Rev Lett ; 92(23): 232301, 2004 Jun 11.
Artigo em Inglês | MEDLINE | ID: mdl-15245151

RESUMO

We present a complete systematics (excitation functions and system-size dependences) of global stopping and side flow for heavy ion reactions in the energy range between 0.09A and 1.93A GeV. For the heaviest system, Au+Au, we observe a plateau of maximal stopping extending from about 0.2A to 0.8A GeV with a fast drop on both sides. The degree of stopping, which is shown to remain significantly below the expectations of a full stopping scenario, is found to be highly correlated to the amount of side flow.

3.
Phys Rev Lett ; 92(7): 072303, 2004 Feb 20.
Artigo em Inglês | MEDLINE | ID: mdl-14995843

RESUMO

Detailed studies of the azimuthal dependence of the mean fragment and flow energies in the Au+Au and Xe+CsI systems are reported as a function of incident energy and centrality. Comparisons between data and model calculations show that the flow energy values along different azimuthal directions could be viewed as snapshots of the fireball expansion with different exposure times. For the same number of participating nucleons more transversally elongated participant shapes from the heavier system produce less collective transverse energy. Good agreement with Boltzmann-Uehling-Uhlenbeck calculations is obtained for a soft nuclear equation of state.

4.
Soc Stud Sci ; 29(6): 889-912, 1999 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-11624111

RESUMO

Twenty years ago, the technology of in vitro fertilization created a new artefact: the human embryo outside the woman's body. In many countries, political debates developed around the artefact. One of the central questions in these debates is whether it is permissible to use human embryos in research and, if so, under what conditions. To date, no uniform answer to this question has been given by the governments and parliaments of the different nation states. This highlights the importance of national cultures and local dynamics in the process of crafting the space for human embryo research. In this paper I approach the issue of the national context by comparing the Dutch and British parliamentary debates on human embryos. Though some arguments used in both debates were similar, the outcomes were very different. In the UK, the Human Fertilisation and Embryology Act was passed in 1990. In the Netherlands, several bills on human embryos have been drafted, but each of them was withdrawn from the proceedings before reaching Parliament. To understand the processes which led to these different outcomes, I scrutinize the roles in the Netherlands of the political parties, of the scientists' lobby and of women speakers, and compare them with the findings of the UK debate. I also reflect upon the role played by gender in these two culturally different political contexts.


Assuntos
Bioética/história , Embrião de Mamíferos , Embrião não Mamífero , Legislação Médica/história , Política , Pesquisa/história , Fertilização in vitro/história , Governo , História do Século XX , Laboratórios/história , Países Baixos , Reino Unido
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