140 research outputs found
Recycling of ultra-high performance fibre-reinforced concrete with a high voltage electric pulse fragmentation process
International audienceThis study deals with the recycling of a particular Ultra-High Performance Fibre Reinforced Concrete (UHPFRC) called Ductal®. This material, characterized by a high mechanical resistance and a high steel fibre content, represent a challenge for the conventional recycling processes. The high voltage electric pulse fragmentation (EPF) technology was investigated here as a potential breakthrough technology for liberating the steel fibres from the sand/cement paste, with the objective to recycle both fractions into new concrete products. The EPF technology relies on highly energetic electrical pulses to selectively fragment composite materials i.e. to generate cracks along grain boundaries. Tests were performed at lab-scale and showed that the steel fibres are liberated in the 0/2 mm size fraction. The influence of the specific energy on EPF performances was investigated. Good recovery rates of the steel fibres were obtained, confirming the potential of EPF for the recycling of UHPFRC
Followup procedure in time-domain F-statistic searches for continuous gravitational waves
Potentially interesting gravitational-wave candidates (outliers) from the
blind all-sky searches have to be confirmed or rejected by studying their
origin and precisely estimating their parameters. We present the design and
first results for the followup procedure of the {\tt Polgraw} all-sky search
pipeline: a coherent search for almost-monochromatic gravitational-wave signals
in several-day long time segments using the -statistic method followed by
the coincidences between the candidate signals. Approximate parameters
resulting in these two initial steps are improved in the final followup step,
in which the signals from detectors are studied separately, together with the
network combination of them, and the true parameters and signal-to-noise values
are established.Comment: 4 pages, 4 figures, published in Proceedings of the Polish
Astronomical Society, vol. 7, 37-40 (2018
Parallel assessment of male reproductive function in workers and wild rats exposed to pesticides in banana plantations in Guadeloupe
<p>Abstract</p> <p>Background</p> <p>There is increasing evidence that reproductive abnormalities are increasing in frequency in both human population and among wild fauna. This increase is probably related to exposure to toxic contaminants in the environment. The use of sentinel species to raise alarms relating to human reproductive health has been strongly recommended. However, no simultaneous studies at the same site have been carried out in recent decades to evaluate the utility of wild animals for monitoring human reproductive disorders. We carried out a joint study in Guadeloupe assessing the reproductive function of workers exposed to pesticides in banana plantations and of male wild rats living in these plantations.</p> <p>Methods</p> <p>A cross-sectional study was performed to assess semen quality and reproductive hormones in banana workers and in men working in non-agricultural sectors. These reproductive parameters were also assessed in wild rats captured in the plantations and were compared with those in rats from areas not directly polluted by humans.</p> <p>Results</p> <p>No significant difference in sperm characteristics and/or hormones was found between workers exposed and not exposed to pesticide. By contrast, rats captured in the banana plantations had lower testosterone levels and gonadosomatic indices than control rats.</p> <p>Conclusion</p> <p>Wild rats seem to be more sensitive than humans to the effects of pesticide exposure on reproductive health. We conclude that the concept of sentinel species must be carefully validated as the actual nature of exposure may varies between human and wild species as well as the vulnerable time period of exposure and various ecological factors.</p
Observation of exclusive DVCS in polarized electron beam asymmetry measurements
We report the first results of the beam spin asymmetry measured in the
reaction e + p -> e + p + gamma at a beam energy of 4.25 GeV. A large asymmetry
with a sin(phi) modulation is observed, as predicted for the interference term
of Deeply Virtual Compton Scattering and the Bethe-Heitler process. The
amplitude of this modulation is alpha = 0.202 +/- 0.028. In leading-order and
leading-twist pQCD, the alpha is directly proportional to the imaginary part of
the DVCS amplitude.Comment: 6 pages, 5 figure
Dependence of Quadrupole Strength in the Transition
Models of baryon structure predict a small quadrupole deformation of the
nucleon due to residual tensor forces between quarks or distortions from the
pion cloud. Sensitivity to quark versus pion degrees of freedom occurs through
the dependence of the magnetic (), electric (), and
scalar () multipoles in the
transition. We report new experimental values for the ratios
and over the range = 0.4-1.8 GeV, extracted from
precision data using a truncated multipole expansion.
Results are best described by recent unitary models in which the pion cloud
plays a dominant role.Comment: 5 pages, 5 figures, 1 table. To be published in Phys. Rev. Lett.
(References, figures and table updated, minor changes.
Measurement of the cosmic ray spectrum above eV using inclined events detected with the Pierre Auger Observatory
A measurement of the cosmic-ray spectrum for energies exceeding
eV is presented, which is based on the analysis of showers
with zenith angles greater than detected with the Pierre Auger
Observatory between 1 January 2004 and 31 December 2013. The measured spectrum
confirms a flux suppression at the highest energies. Above
eV, the "ankle", the flux can be described by a power law with
index followed by
a smooth suppression region. For the energy () at which the
spectral flux has fallen to one-half of its extrapolated value in the absence
of suppression, we find
eV.Comment: Replaced with published version. Added journal reference and DO
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