EU Policies in the Democratic Republic of Congo: Try and Fail?

This paper argues that even though EU policies in the DRC integrated different components of human security – namely human rights protection, the restoration of law and order, and effective multilateralism – in practice these policies have had mixed success in realizing the objective of human security. This can be explained by three main reasons: (i) EU policies are based on a number of premises about how peace and human security can best be achieved, but these premises are overly simplistic, and in most cases tend to overlook or are disconnected from complexities on the ground; (ii) since the end of the transition in 2006, the EU saw its influence as dominant diplomatic and conflict management actor gradually weakening, and has focused on its role as a development actor, with a specific focus on the implementation of technical projects rather than on the development of a strategic policy on the DRC; and (iii) there is a general lack of political will from Congolese state authorities to engage with donor strategies and to support initiatives that promote a genuine national reform

Cosmic radioactivities

Radionuclides with half-lives ranging from some years to billions of years presumably synthesized outside of the solar system are now recorded in ``live'' or ``fossil'' form in various types of materials, like meteorites or the galactic cosmic rays. They bring specific astrophysical messages the deciphering of which is briefly reviewed here, with special emphasis on the contribution of Dave Schramm and his collaborators to this exciting field of research. Short-lived radionuclides are also present in the Universe today, as directly testified by the gamma-ray lines emitted by the de-excitation of their daughter products. A short review of recent developments in this field is also presented.Comment: Invited Review to appear in New Astronomy, 16 pages, 2 figure

From the microcosm of the atomic nuclei to the macrocosm of the stars

A necessary condition for the reliable modelling of the structure or evolution of the stars and of their concomitant nucleosynthesis is the availability of good quality nuclear data in a very wide area of the chart of nuclides. This short review presents a non-exhaustive list of nuclear data of astrophysics interest (masses, $\beta$-decays, thermonuclear and non-thermonuclear reaction rates) for nuclides at the bottom of the valley of nuclear stability (mainly involved in the modelling of non-explosive phases of stellar evolution), or for more or less highly exotic nuclides (to be considered in the description of stellar explosions). Special emphasis is put on the importance of providing quality nuclear data bases that can be easily used by astrophysicists.Comment: 6 pages, To appear in Proceedings of International Conference on Nuclear Data for Science and Technology 2007 (ND2007), Nice, Franc

Synthesis of 19F in Wolf-Rayet stars

Meynet and Arnould (1993) have suggested that Wolf-Rayet (WR) stars could significantly contaminate the Galaxy with 19F. In their scenario, 19F is synthesized at the beginning of the He-burning phase from the 14N left over by the previous CNO-burning core, and is ejected in the interstellar medium when the star enters its WC phase. Recourse to CNO seeds makes the 19F yields metallicity-dependent. These yields are calculated on grounds of detailed stellar evolutionary sequences for an extended range of initial masses (from 25 to 120 Msol) and metallicities (Z = 0.008, 0.02 and 0.04). The adopted mass loss rate prescription enables to account for the observed variations of WR populations in different environments. The 19F abundance in the WR winds of 60 Msol model stars is found to be about 10 to 70 times higher than its initial value, depending on the metallicity. This prediction is used in conjunction with a very simple model for the chemical evolution of the Galaxy to predict that WR stars could be significant (dominant?) contributors to the solar system fluorine content. We also briefly discuss the implications of our model on the possible detection of fluorine at high redshift.Comment: 2 figures; requires LaTeX A&A class file; accepted for publication in Astron. Astrophy

Hope and Inquietudes in Nucleo-cosmochronology

Critical views are presented on some nucleo-cosmochronological questions. Progress has been made recently in the development of the 187Re-187Os cosmochronometry. From this, there is good hope for this clock to become of the highest quality for the nuclear dating of the Universe. The simultaneous observation of Th and U in ultra-metal-poor stars would also be a most interesting prospect. In contrast, a serious inquietude is expressed about the reliability of the chronometric attempts based on the classical 232Th-238U and 235U-238U pairs, as well as on the Th (without U) abundance determinations in ultra-metal poor stars.Comment: 9 pages, no figures; ASP Conference Series: "Astrophysical Ages and Time Scales

Nuclear Astrophysics

Nuclear astrophysics is that branch of astrophysics which helps understanding some of the many facets of the Universe through the knowledge of the microcosm of the atomic nucleus. In the last decades much advance has been made in nuclear astrophysics thanks to the sometimes spectacular progress in the modelling of the structure and evolution of the stars, in the quality and diversity of the astronomical observations, as well as in the experimental and theoretical understanding of the atomic nucleus and of its spontaneous or induced transformations. Developments in other sub-fields of physics and chemistry have also contributed to that advance. Many long-standing problems remain to be solved, however, and the theoretical understanding of a large variety of observational facts needs to be put on safer grounds. In addition, new questions are continuously emerging, and new facts endanger old ideas. This review shows that astrophysics has been, and still is, highly demanding to nuclear physics in both its experimental and theoretical components. On top of the fact that large varieties of nuclei have to be dealt with, these nuclei are immersed in highly unusual environments which may have a significant impact on their static properties, the diversity of their transmutation modes, and on the probabilities of these modes. In order to have a chance of solving some of the problems nuclear astrophysics is facing, the astrophysicists and nuclear physicists are obviously bound to put their competence in common, and have sometimes to benefit from the help of other fields of physics, like particle physics, plasma physics or solid-state physics.Comment: LaTeX2e with iopart.cls, 84 pages, 19 figures (graphicx package), 374 updated references. Published in Reports on Progress in Physics, vol.62, pp. 395-464 (1999

The production of short-lived radionuclides by new non-rotating and rotating Wolf-Rayet model stars

It has been speculated that WR winds may have contaminated the forming solar system, in particular with short-lived radionuclides (half-lives in the approximate 10^5 - 10^8 y range) that are responsible for a class of isotopic anomalies found in some meteoritic materials. We revisit the capability of the WR winds to eject these radionuclides using new models of single non-exploding WR stars with metallicity Z = 0.02. The earlier predictions for non-rotating WR stars are updated, and models for rotating such stars are used for the first time in this context. We find that (1) rotation has no significant influence on the short-lived radionuclide production by neutron capture during the core He-burning phase, and (2) 26Al, 36Cl, 41Ca, and 107Pd can be wind-ejected by a variety of WR stars at relative levels that are compatible with the meteoritic analyses for a period of free decay of around 10^5 y between production and incorporation into the forming solar system solid bodies. We confirm the previously published conclusions that the winds of WR stars have a radionuclide composition that can meet the necessary condition for them to be a possible contaminating agent of the forming solar system. Still, it remains to be demonstrated from detailed models that this is a sufficient condition for these winds to have provided a level of pollution that is compatible with the observations.Comment: 8 pages, 8 figure

Fluorine production in intermediate-mass stars

The 19F production during the first dozen thermal pulses of AGB stars with (M=3,Z=0.02), (M=6,Z=0.02) and (M=3,Z=0.001) is investigated on grounds of detailed stellar models and of revised rates for 15N(a,g)19F and 18O(a,g)22Ne. These calculations confirm an early expectation that 19F {\it is} produced in AGB thermal pulses. They also enlarge substantially these previous results by showing that the variations of the level of 19F production during the evolution is very sensitive to the maximum temperature reached at the base of the pulse. These variations are analyzed in detail, and are shown to result from a subtle balance between different nuclear effects (mainly 19F production or destruction in a pulse, and 15N synthesis during the interpulse), possibly super-imposed on dilution effects in more or less extended pulse convective tongues. Our calculations, as most others, do not predict the third dredge-up self- consistently. When parametrized, it appears that our models of intermediate-mass AGB stars are able to account only for the lowest 19F overabundances observed in solar-metallicity MS, S and C stars. That conclusion is expected to hold true for low-mass stars when F production results from secondary 13C only. Massive AGB stars, on the other hand, are not expected to build up large surface F abundanc- es. Therefore, the large F overabundance reported for the super Li-rich star WZ Cas (where HBB is supposed to be operating) remains unexplained so far. Our results for the (M=3,Z=0.001) star indicate that F surface overabundances can also be expected in low-metallicity stars provided that third dredge-ups occur after the early cool pulses. The relative increase in the surface 19F/12C ratio is, however, lower in the low-metallicity than in the solar-metallicity star. No observations areComment: 27 pages, includes figures, postcript file (A&A format, 15 pages including figures) can be found via anonymous ftp at ftp://obsftp.unige.ch/pub/mowlavi/fluor.ps.gz ; accepted by A&