Mapping semi-natural grassland has become increasingly important with regard to climate variability, invasive species, and the intensification of land use. At the same time, adequate field data ...collection is of pivotal importance for national and international reporting obligations, such as the European Habitats Directive. We present a remote-sensing-based monitoring framework for a Natura 2000 site with a heterogeneous composition of different grassland communities, using the Random Forest algorithm. Automated training data selection was successfully implemented based on the Random Forest proximity measure (Overall Accuracy ranging from 77.5-86.5%). RapidEye acquisitions originating from the onset of vegetation (prespring and first spring) and senescence (late summer and first autumn) were identified as important phenological phases for mapping semi-natural grassland communities. The derived probability maps of occurrences for each grassland class captured transitions between grassland communities and are therefore a better approximation of real-world conditions compared to classical, discrete maps.
At the JRC-Geel's RadioNuclide Metrology sector, a Monte Carlo code based on EGSnrc, and a general purpose calculation sheet implemented in Microsoft Excel®, have been developed to make the ...quantitative gamma-ray spectrometry analysis of samples simpler and more robust. The further aim is that the software can be used by non-experts in gamma-ray spectrometry e.g. external researchers using JRC-Geel's facilities through the EUFRAT transnational access scheme. This paper presents the developed Monte Carlo software and the functionality included in the calculation sheet.
•A Monte Carlo code has been developed and validated using EGSnrc.•A radionuclide decay generator has been written and validated.•Detection efficiency can be calculated for High Purity Germanium detector.•A flexible and user friendly analysis software using MS Excel® has been developed.•Functionalities and performances of the software are presented.
A search for double-beta decay of
190
Pt and
198
Pt with emission of
γ
-ray quanta was realized at the HADES underground laboratory with a 148 g platinum sample measured by two ultralow-background ...HPGe detectors over 8946 h. The isotopic composition of the platinum sample has been measured with high precision using inductively coupled plasma mass spectrometry. New lower limits for the half-lives of
190
Pt relative to different channels and modes of the decays were set on the level of
lim
T
1
/
2
∼
10
14
–
10
16
year. A possible exact resonant
0
ν
K
N
transition to the 1,2 1326.9 keV level of
190
Os is limited for the first time as
T
1
/
2
≥
2.5
×
10
16
year. A new lower limit on the double-beta decay of
198
Pt to the first excited level of
198
Hg was set as
T
1
/
2
≥
3.2
×
10
19
year, one order of magnitude higher than the limit obtained in the previous experiment.
Is decay constant? Pommé, S.; Stroh, H.; Altzitzoglou, T. ...
Applied radiation and isotopes,
April 2018, 2018-Apr, 2018-04-00, 20180401, Volume:
134
Journal Article
Peer reviewed
Open access
Some authors have raised doubt about the invariability of decay constants, which would invalidate the exponential-decay law and the foundation on which the common measurement system for radioactivity ...is based. Claims were made about a new interaction – the fifth force – by which neutrinos could affect decay constants, thus predicting changes in decay rates in correlation with the variations of the solar neutrino flux. Their argument is based on the observation of permille-sized annual modulations in particular decay rate measurements, as well as transient oscillations at frequencies near 11 year−1 and 12.7 year−1 which they speculatively associate with dynamics of the solar interior. In this work, 12 data sets of precise long-term decay rate measurements have been investigated for the presence of systematic modulations at frequencies between 0.08 and 20 year−1. Besides small annual effects, no common oscillations could be observed among α, β-, β+ or EC decaying nuclides. The amplitudes of fitted oscillations to residuals from exponential decay do not exceed 3 times their standard uncertainty, which varies from 0.00023 % to 0.023 %. This contradicts the assertion that 'neutrino-induced' beta decay provides information about the deep solar interior.
•Repeatedly measured decay rates of radionuclides.•No cycles between 1 and 20 year−1 in residuals from exponential decay.•No evidence of variable decay constants due to solar neutrinos.•No effect from 11.1-year solar cycle on decay rate.
Using the NAXSUN technique developed at the JRC-Geel, the cross section functions for the neutron induced reactions
187
Re(n,p)
187
W and
185
Re(n,3n)
183
Re have been measured in the energy range ...between 13.08 MeV and 19.5 MeV. These data are the first experimentally obtained values for those nuclear reactions in this neutron energy range. Obtained results have been compared with existing evaluated data from ENDF/B-VII 0, JEFF 3.3, JEFF 3.2, BROND 3.1, JEF - 2.2, JENDL, ROSFO ND-2010, TENDL-2017, EAF-2010, FENDL-3.1c. The TALYS 1.9 and EMPIRE 3.2.3 calculations were performed using different available models and calculations using several semi-empirical existing formulas. A comparison between theoretical model calculations and experimental results was made.
First results of a half-life measurement of (209)Po show 20% discrepancy with the formerly recommended value of 102 (5) years, which was based on a single experiment performed in 1956. After one year ...of measurement, a statistical uncertainty on T1/2 of 3.5% has been reached and effects of long-term instability are assumed to be less than 5%. The preliminary half-life value obtained in this work, 120 (6) years, supports the newly determined value of 125.2 (33) years by Collé et al. (2014). The 20% error in the half-life has an impact on numerous measurements in which aged (209)Po solutions were used as a tracer.
Following the accident at the Fukushima Daiichi nuclear power plant, a campaign of sampling and measuring anthropogenic radionuclides in North Pacific seawater was set up. The main aim was to study ...natural processes using these radionuclides as tracers. Because of dilution, the activities of anthropogenic radionuclides at long range were very low and their measurement required advanced pre-concentration techniques and underground gamma-ray spectrometry. Data and metrological aspects of the measurements using HPGe-detectors are presented and discussed.
•The use of anthropogenic radionuclides from Fukushima as tracers is described.•Results from plankton and particulate matter are presented.•Emergency preparedness for tracer studies is discussed.
BACKGROUND: In humans, fetal microchimeric cells transferred to maternal tissues during pregnancy can adopt a hepatocyte phenotype. Our objective was to determine whether fetal cells participate in ...the response to specific murine post-partum hepatic injuries. METHODS: Wild-type female mice were bred to males transgenic for the enhanced green fluorescent protein (GFP) (n = 42). Following delivery, we created models of chemical or surgical injury with carbon tetrachloride (CCl4) injection or by performing partial hepatectomy. Liver injury was assessed histologically. Fetal cells in maternal liver were detected and measured by real-time PCR amplification of the gfp transgene and by immunofluorescence using anti-GFP antibodies. RESULTS: PCR results showed that in chemical but not surgical injury, fetal GFP+ cells were detectable in maternal liver and spleen and that fetal cell presence was significantly increased over time following injury (4 versus 8 weeks, P = 0.006 for liver and P = 0.0006 for spleen). In some animals, following chemical injury, GFP+ cells were detected by immunofluorescence. CONCLUSIONS: The results of this preliminary study suggest that specific types of injury may elicit different fetal cell responses in maternal organs. There is a significant effect of time on fetal cell presence in liver and spleen. Furthermore, real-time PCR amplification is more sensitive than immunofluorescence for the detection of microchimeric fetal cells.
First results of a half-life measurement of 209Po show 20% discrepancy with the formerly recommended value of 102 (5) years, which was based on a single experiment performed in 1956. After one year ...of measurement, a statistical uncertainty on T1/2 of 3.5% has been reached and effects of long-term instability are assumed to be less than 5%. The preliminary half-life value obtained in this work, 120 (6) years, supports the newly determined value of 125.2 (33) years by Collé et al. (2014). The 20% error in the half-life has an impact on numerous measurements in which aged 209Po solutions were used as a tracer.
•Measured half-life of 209Po is 120 (6)a.•The formerly recommended value was in error by 20%.•Measurement results using 209Po as a tracer are affected.•The error persisted for half a century.
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