1,118 research outputs found
Isotopic distribution of fission fragments in collisions between 238U beam and 9Be and 12C targets at 24 MeV/u
Inverse kinematics coupled to a high-resolution spectrometer is used to
investigate the isotopic yields of fission fragments produced in reactions
between a 238U beam at 24 MeV/u and 9Be and 12C targets. Mass, atomic number
and isotopic distributions are reported for the two reactions. These
informations give access to the neutron excess and the isotopic distribution
widths, which together with the atomic-number and mass distributions are used
to investigate the fusion-fission dynamics.Comment: Submitted to PR
Double di ffential fragmentation cross sections measurements of 95 MeV/u 12C on thin targets for hadrontherapy
During therapeutic treatment with heavy ions like carbon, the beam undergoes
nuclear fragmentation and secondary light charged particles, in particular
protons and alpha particles, are produced. To estimate the dose deposited into
the tumors and the surrounding healthy tissues, an accurate prediction on the
fluences of these secondary fragments is necessary. Nowadays, a very limited
set of double di ffential carbon fragmentation cross sections are being
measured in the energy range used in hadrontherapy (40 to 400 MeV/u).
Therefore, new measurements are performed to determine the double di ffential
cross section of carbon on di erent thin targets. This work describes the
experimental results of an experiment performed on May 2011 at GANIL. The
double di ffential cross sections and the angular distributions of secondary
fragments produced in the 12C fragmentation at 95 MeV/u on thin targets (C,
CH2, Al, Al2O3, Ti and PMMA) have been measured. The experimental setup will be
precisely described, the systematic error study will be explained and all the
experimental data will be presented.Comment: Submitted to PR
Clinical epidemiology of laboratory-confirmed Buruli ulcer in Benin: a cohort study
Background Buruli ulcer, caused by Mycobacterium ulcerans, was identifi ed as a neglected emerging infectious disease
by WHO in 1998. Although Buruli ulcer is the third most common mycobacterial disease worldwide, understanding
of the disease is incomplete. We analysed a large cohort of laboratory-confi rmed cases of Buruli ulcer from Pobè,
Benin, to provide a comprehensive description of the clinical presentation of the disease, its variation with age and
sex, and its eff ect on the occurrence of permanent functional sequelae.
Methods Between Jan 1, 2005, and Dec 31, 2011, we prospectively collected clinical and laboratory data from all
patients with Buruli ulcer diagnosed at the Centre de Dépistage et de Traitement de l’Ulcère de Buruli in Pobè, Benin.
We followed up patients to assess the frequency of permanent functional sequelae. All analyses were done on cases
that were laboratory confi rmed.
Findings 1227 cases of laboratory-confi rmed Buruli ulcer were included in the analysis. Typically, patients with Buruli
ulcer were children (median age at diagnosis 12 years) presenting with a unique (1172 [96%]) large (≥15 cm, 444 [36%])
ulcerative (805 [66%]) lesion of the lower limb (733 [60%]). Atypical clinical presentation of Buruli ulcer included
Buruli ulcer osteomyelitis with no identifi able present or past Buruli ulcer skin lesions, which was recorded in at least
14 patients. The sex ratio of Buruli ulcer widely varied with age, with male patients accounting for 57% (n=427) of
patients aged 15 years and younger, but only 33% (n=158) of those older than 15 years (odds ratio [OR] 2·59,
95% CI 2·04–3·30). Clinical presentation of Buruli ulcer was signifi cantly dependent on age and sex. 54 (9%) male
patients had Buruli ulcer osteomyelitis, whereas only 28 (4%) of female patients did (OR 2·21, 95% CI 1·39–3·59).
1 year after treatment, 229 (22% of 1043 with follow-up information) patients presented with permanent functional
sequelae. Presentation with oedema, osteomyelitis, or large (≥15 cm in diameter), or multifocal lesions was
signifi cantly associated with occurrence of permanent functional sequelae (OR 7·64, 95% CI 5·29–11·31) and
operationally defi nes severe Buruli ulcer.
Interpretation Our fi ndings have important clinical implications for daily practice, including enhanced surveillance
for early detection of osteomyelitis in boys; systematic search for M ulcerans in osteomyelitis cases of non-specifi c
aspect in areas endemic for Buruli ulcer; and specifi c disability prevention for patients presenting with osteomyelitis,
oedema, or multifocal or large lesions. Our fi ndings also suggest a crucial underestimation of the burden of Buruli
ulcer in Africa and raise key questions about the contribution of environmental and physiopathological factors to the recorded heterogeneity of the clinical presentation of Buruli ulcer
Thinking through time: From collective memories to collective futures
In this chapter I look at the links between collective memory and the imagination of collective futures. Drawing on works on imagination and autobiographical memory, I first discuss the role of past experiences in imagining the future. I then explore the consequences of such a perspective for collective memories and collective futures, which will lead me to argue that the former provides the basis for the latter. Three case studies are presented, each illustrating a different type of relation between collective memory and collective imagination: 1) collective memory as a frame of reference to imagine the future; 2) collective memory as a source of experiences and examples to imagine what is likely, possible or desirable; and 3) collective memory as generalisable experience from which representations of the world – Personal World Philosophies – are constructed and in turn used to imagine the collective future. This will lead me to the conclusion that representations of the world are characterised by “temporal heteroglossia”, the simultaneous presence of multiple periods of time, and that they mediate the relation between collective memory and collective imagination, allowing us to “think through time”
Collapse of the N=28 shell closure in Si
The energies of the excited states in very neutron-rich Si and
P have been measured using in-beam -ray spectroscopy from the
fragmentation of secondary beams of S at 39 A.MeV. The low 2
energy of Si, 770(19) keV, together with the level schemes of
P provide evidence for the disappearance of the Z=14 and N=28
spherical shell closures, which is ascribed mainly to the action of
proton-neutron tensor forces. New shell model calculations indicate that
Si is best described as a well deformed oblate rotor.Comment: 4 pages, 3 figures, accepted for publication in Phys. Rev. let
Prolate-Spherical Shape Coexistence at N=28 in S
The structure of S has been studied using delayed and
electron spectroscopy at \textsc{ganil}. The decay rates of the 0
isomeric state to the 2 and 0 states have been measured for the
first time, leading to a reduced transition probability
B(E2~:~20= 8.4(26)~efm and a monopole
strength (E0~:~00
=~8.7(7)10. Comparisons to shell model calculations point
towards prolate-spherical shape coexistence and a phenomenological two level
mixing model is used to extract a weak mixing between the two configurations.Comment: 5 pages, 3 figures, accepted for publication in Physical Review
Letter
Spectroscopy of F
The structure of the weakly-bound F odd-odd nucleus,
produced from Na nuclei, has been investigated at GANIL by means of
the in-beam -ray spectroscopy technique. A single -line is
observed at 657(7) keV in F which has been ascribed to the decay of
the excited J= state to the J=1 ground state. The possible presence of
intruder negative parity states in F is also discussed.Comment: 3 pages, 1 figure, accepted for publication in Physical Review
Comparison of two analysis methods for nuclear reaction measurements of 12C +12C interactions at 95 MeV/u for hadrontherapy
During therapeutic treatment with heavier ions like carbon, the beam
undergoes nuclear fragmentation and secondary light charged particles, in
particular protons and alpha particles, are produced. To estimate the dose
deposited into the tumors and the surrounding healthy tissues, the accuracy
must be higher than (3% and1 mm). Therefore, measurements are
performed to determine the double differential cross section for different
reactions. In this paper, the analysis of data from 12C +12C reactions at 95
MeV/u are presented. The emitted particles are detected with
\DeltaEthin-\DeltaEthick-E telescopes made of a stack of two silicon detectors
and a CsI crystal. Two different methods are used to identify the particles.
One is based on graphical cuts onto the \DeltaE-E maps, the second is based on
the so-called KaliVeda method using a functional description of \DeltaE versus
E. The results of the two methods will be presented in this paper as well as
the comparison between both
Three-body correlations in Borromean halo nuclei
Three-body correlations in the dissociation of two-neutron halo nuclei are
explored using a technique based on intensity interferometry and Dalitz plots.
This provides for the combined treatment of both the n-n and core-n
interactions in the exit channel. As an example, the breakup of 14Be into
12Be+n+n by Pb and C targets has been analysed and the halo n-n separation
extracted. A finite delay between the emission of the neutrons in the reaction
on the C target was observed and is attributed to 13Be resonances populated in
sequential breakup.Comment: 5 pages, 4 figures, submitted to PR
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