Asari (=Manila) clam, Ruditapes philippinarum, is the second bivalve mollusc in terms of production in the world and, in many coastal areas, can beget important socio-economic issues. In Europe, this ...species was introduced after 1973. In Arcachon Bay, after a decade of aquaculture attempt, Asari clam rapidly constituted neo-naturalized population which is now fished. However, recent studies emphasized the decline of population and individual performances. In the framework of a national project (REPAMEP), some elements of fitness, stressors and responses in Arcachon Bay were measured and compared to international data (41 publications, 9 countries). The condition index (CI = flesh weight/shell weight) was the lowest among all compared sites. Variation in average Chla concentration explained 30% of variation of CI among different areas. Among potential diseases, perkinsosis was particularly prevalent in Arcachon Bay, with high abundance, and Asari clams underwent Brown Muscle Disease, a pathology strictly restricted to this lagoon. Overall element contamination was relatively low, although arsenic, cobalt, nickel and chromium displayed higher values than in other ecosystems where Asari clam is exploited. Finally, total hemocyte count (THC) of Asari clam in Arcachon Bay, related to the immune system activity, exhibited values that were also under what is generally observed elsewhere. In conclusion, this study, with all reserves due to heterogeneity of available data, suggest that the particularly low fitness of Asari clam in Arcachon Bay is due to poor trophic condition, high prevalence and intensity of a disease (perkinsosis), moderate inorganic contamination, and poor efficiency of the immune system.
•Asari clams characteristics are compared among 9 countries through 41 references.•30% of condition index variation is explained by chlorophyll a concentration.•Chla and diseases explain most of Asari clam poor fitness in Arcachon Bay.
Radiation hardening of silicon detectors Lemeilleur, F
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
09/1999, Letnik:
434, Številka:
1
Journal Article
Recenzirano
The radiation hardness of high grade silicon detectors is summarized in terms of an increase of the diode reverse current, evolution of the full depletion voltage and charge collection efficiency. ...With the aim of improving their radiation tolerance, detectors have been produced from non-standard, float-zone silicon containing various atomic impurities and from epitaxial silicon materials. Some recent results concerning their radiation hardness are presented.
New irradiation zones at the CERN-PS Glaser, M; Durieu, L; Lemeilleur, F ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
04/1999, Letnik:
426, Številka:
1
Journal Article
Recenzirano
After the upgrade of the CERN-PS East Hall, one irradiation zone with 24
GeV/
c protons is foreseen to be operational by the second half of 1998. Another irradiation zone with about 1
MeV neutrons ...will be commissioned by the first half of 1999.
Status and development of radiation hard silicon detectors Lemeilleur, F.
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
11/1998, Letnik:
418, Številka:
1
Journal Article
Recenzirano
After a review of the results achieved on the radiation hardness of standard silicon detectors, the aim of the ROSE/RD48 collaboration is presented as well as some new results on radiation hardening ...of silicon detectors.
The subject of radiation damage to Si detectors induced by 24-GeV/c protons and nuclear reactor neutrons has been studied. Detectors fabricated on single-crystal silicon enriched with various ...impurities have been tested. Significant differences in electrically active defects have been found between the various types of material. The results of the study suggest for the first time that the widely used nonionizing energy loss (NIEL) factors are insufficient for normalization of the electrically active damage in case of oxygen- and carbon-enriched silicon detectors. It has been found that a deliberate introduction of impurities into the semiconductor can affect the radiation hardness of silicon detectors.
Studies of radiation hardness of oxygen enriched silicon detectors Ruzin, A.; Casse, G.; Glaser, M. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
04/1999, Letnik:
426, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Detectors for high-energy particles sustain a substantial amount of structural defects induced by the particles during the operation period. Some of the defects have been found to be electrically ...active, degrading the detector's performance. Understanding the mechanisms of the electrical activities and learning to suppress their influence are essential if long “lifetime” detectors are required. This work reports about radiation hardness of silicon P-I-N devices fabricated from oxygen enriched high resistivity material. The high and nearly uniform concentration of oxygen in Float Zone silicon has been achieved by diffusion of oxygen from SiO
2 layers.
The electrical characteristics of non-irradiated and irradiated n-type silicon detectors (p
+–n–n
+ diode) are extracted by fitting a charge transport model to a set of experimental data obtained ...from the measurement of the current pulse response induced by α and β particles in non-irradiated and irradiated silicon detectors. The detectors have been irradiated either with ≈1
MeV neutrons up to a fluence of 11.2×10
13
n/cm
2 or with 24
GeV/
c protons up to a fluence of 10.6×10
13
p/cm
2. After n to p-type inversion, a small junction on the p
+ side of the detector is introduced to fit the experimental data and therefore to account for the evolution of the electrical characteristics of the detectors with fluence.
The bacterial communities associated with the cockle (Cerastoderma edule) were investigated at the individual level through a 10-month monitoring programme. Temporal changes and those changes ...associated with a common parasite of the cockle, Bucephalus minimus, were investigated by monthly sampling of individuals, selected based on their shell length (cohort monitoring). Cockle bacterial community abundance (CBCA) and diversity (CBCD) were estimated by epifluorescence microscopy counts and automated ribosomal intergenic spacer analysis, respectively. CBCA showed a temporal pattern peaking at 30×10⁶ cells per gram of cockle flesh and intervalval liquid in October and a significant 1.8-fold increase linked with B. minimus occurrence. CBCD was characterized by 112±26 intergenic transcribed spacer (ITS) per individual and showed a relative homology between individuals (52 ± 6%, Jaccard similarity) in spite of more than 30% of rare ITS. Consistent with an undisturbed evolution of the condition index of the studied cohort individuals as an estimate of their physiological state, neither temporal nor parasite-induced change in CBCA has been related to marked changes in CBCD.
Charge transport in non-irradiated and irradiated silicon detectors Leroy, C.; Roy, P.; Casse, G.L. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
09/1999, Letnik:
434, Številka:
1
Journal Article
Recenzirano
Odprti dostop
A model describing the transport of the charge carriers generated in n-type silicon detectors by ionizing particles is presented. In order to reproduce the experimental current pulse responses ...induced by α and β particles in non-irradiated and irradiated detectors up to fluences (
Φ) much beyond the n to p-type inversion, an n-type region 15 μm deep is introduced on the p
+ side of the diode. This model also gives mobilities which decrease linearly up to fluences of around 5×10
13 particles/cm
2 and beyond, converging to saturation values of about 1000 and 450 cm
2/V
s for electrons and holes, respectively. The charge carrier lifetime degradation with increased fluence, due to trapping, is responsible for a predicted charge collection deficit for β particles and for α particles which is found to agree with direct CCE measurements.
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