scholarly journals Vertical distribution of 137Cs and natural radioactivity in core sediments of Thermaikos Gulf, northwestern Aegean Sea

2019 ◽  
Vol 17 ◽  
pp. 35
Author(s):  
G. Eleftheriou ◽  
C. Tsabaris ◽  
E. Philis-Tsirakis ◽  
E. Kamberi ◽  
R. Vlastou
Keyword(s):  
Activity Concentration ◽  
Aegean Sea ◽  
Sedimentation Rates ◽  
Decay Products ◽  
Radon Daughters ◽  
Vertical Distributions ◽  
Order Of Magnitude ◽  
Superficial Sediments ◽  
The Mean ◽  
Natural Series

Sub-superficial sediments have been collected from the Thermaikos Gulf, located in the NW Aegean Sea, in order to determine sedimentation rates using vertical distributions of 137Cs and 210Pb. In addition measurements of the characteristic radionuclides of the 238U and 232Th natural series has also been performed to better understand the transport and the sedimentation process in a marine environment, which is strongly influenced by the main North Greece rivers. The sedimentation rates of the five selected cores using the two methods were consistent and varied from 0.20 ± 0.01 till 0.30 ± 0.02 cm y-1. The mean sedimentation rates derived with both methods are enhanced during the last ten years compared to previous values at the studied region by one order of magnitude, due to human implications. The activity concentration of the 238U decay products does not exhibit variation along the depth. The activities of 226Ra are enhanced (~30 %) compared to the activities of radon daughters (214Pb, 214Bi) especially at the surface layer. The results of the correlation between 232Th decay products and 40K indicate that there is positive correlation between their averaged activities. The good proportionality between 232Th and 40K concentrations may be attributed to the fact that thorium is a particularly insoluble element in water.

scholarly journals Radioactivity Monitoring at North Aegean Sea Integrating In-Situ Sensor in an Ocean Observing Platform

2021 ◽  
Vol 9 (1) ◽  
pp. 77
Author(s):  
Christos Tsabaris ◽  
Effrossyni G. Androulakaki ◽  
Dionysios Ballas ◽  
Stylianos Alexakis ◽  
Leonidas Perivoliotis ◽  
...  
Keyword(s):  
Activity Concentration ◽  
Detection System ◽  
Aegean Sea ◽  
Full Spectrum ◽  
The North ◽  
Radioactivity Monitoring ◽  
Order Of Magnitude ◽  
North Aegean ◽  
In Situ Sensor ◽  
North Aegean Sea

The integration of the radioactivity spectrometer KATERINA II in a fixed station (buoy) of the POSEIDON network at the North Aegean Sea within the framework of MARRE Project is presented. The acquisition period lasted from 20 November 2019 till 22 February 2020. An intense increment of the activity concentration of radon progenies (up to an order of magnitude) was recorded during rainfall. More specifically, the 214Bi activity concentration varied from 0.09 to 0.53 Bq L−1 without rainfall and the 214Pb activity concentration varied from 0.14 to 0.81 Bq L−1. The 214Bi activity concentration during rainfall ranged from 0.4 to 5.4 Bq L−1 and of 214Pb from 0.3 to 5.3 Bq L−1. The minimum detectable activity of the KATERINA II detection system for measuring low level activities of 137Cs is optimized applying background subtraction and the full spectrum analysis technique.

Aktivitätskonzentration der vom Personal einer Radiojodtherapiestation eingeatmeten Luft

1987 ◽  
Vol 26 (03) ◽  
pp. 143-146 ◽  
Author(s):  
H. Fill ◽  
M. Oberladstätter ◽  
J. W. Krzesniak
Keyword(s):  
Nuclear Medicine ◽  
Length Of Stay ◽  
Activity Concentration ◽  
Threshold Value ◽  
Whole Body ◽  
Therapeutic Activity ◽  
External Radiation ◽  
Oral Application ◽  
Exhaled Air ◽  
The Mean

The mean activity concentration of1311 during inhalation by the nuclear medicine personnel was measured at therapeutic activity applications of 22 GBq (600 mCi) per week. The activity concentration reached its maximum in the exhaled air of the patients 2.5 to 4 hours after oral application. The normalized maximum was between 2 • 10−5 and 2 • 10−3 Bq-m−3 per administered Bq. The mean activity concentration of1311 inhaled by the personnel was 28 to 1300 Bq-m−3 (0.8 to 35 nCi-rrf−3). From this the1311 uptake per year was estimated to be 30 to 400 kBq/a (x̄ = 250, SD = 50%). The maximum permitted uptake from air per year is, according to the German and Austrian radiation protection ordinances 22/21 µiCi/a (= 8 • 105 Bq/a). At maximum 50% and, on the average, 30% of this threshold value are reached. The length of stay of the personnel in the patient rooms is already now limited to such an extent that 10% of the maximum permissible whole-body dose for external radiation is not exceeded. Therefore, increased attention should be paid also to radiation exposure by inhalation.

scholarly journals Relaxation Times in Strictly Disk Systems

1971 ◽  
Vol 10 ◽  
pp. 15-19
Author(s):  
George B. Rybicki
Keyword(s):  
Numerical Experiments ◽  
Relaxation Times ◽  
Galactic Structure ◽  
Large Numbers ◽  
Order Of Magnitude ◽  
Vlasov Limit ◽  
The Mean ◽  
Gravitating Systems

AbstractIt is shown that the time of relaxation by particle encounters of self-gravitating systems in the plane interacting by 1/r2 forces is of the same order of magnitude as the mean orbit time. Therefore such a system does not have a Vlasov limit for large numbers of particles, unless appeal is made to some non-zero thickness of the disk. The relevance of this result to numerical experiments on galactic structure is discussed.

Evolution of 137Cs Activity Concentration in the Aegean Sea

2021 ◽  
Author(s):  
Christos Tsabaris ◽  
Georgios Eleftheriou ◽  
Filothei K. Pappa ◽  
Heleni Kaberi ◽  
Stylianos Iliakis ◽  
...  
Keyword(s):  
Activity Concentration ◽  
Aegean Sea ◽  
137Cs Activity ◽  
137Cs Activity Concentration

scholarly journals Using the SWEPT Methodology for a Preliminary Wind Potential Estimation

2014 ◽  
Vol 2014 ◽  
pp. 1-7
Author(s):  
Jean-Luc Menet
Keyword(s):  
Wind Turbine ◽  
Characteristic Curve ◽  
Rayleigh Distribution ◽  
Mean Velocity ◽  
Technical Data ◽  
Wind Potential ◽  
Order Of Magnitude ◽  
General Data ◽  
The Mean ◽  
A Site

The implantation of wind turbines generally follows a wind potential study which is made using specific numerical tools; the generated expenses are only acceptable for great projects. The purpose of the present paper is to propose a simplified methodology for the evaluation of the wind potential, following three successive steps for the determination of (i) the mean velocity, either directly or by the use of the most occurrence velocity (MOV); (ii) the velocity distribution coming from the single knowledge of the mean velocity by the use of a Rayleigh distribution and a Davenport-Harris law; (iii) an appropriate approximation of the characteristic curve of the turbine, coming from only two technical data. These last two steps allow calculating directly the electric delivered energy for the considered wind turbine. This methodology, called the SWEPT approach, can be easily implemented in a single worksheet. The results returned by the SWEPT tool are of the same order of magnitude than those given by the classical commercial tools. Moreover, everybody, even a “neophyte,” can use this methodology to obtain a first estimation of the wind potential of a site considering a given wind turbine, on the basis of very few general data.

Infrared spectra, rotational correlation functions, and intermolecular mean squared torques in compressed gaseous methane

1968 ◽  
Vol 46 (11) ◽  
pp. 1331-1340 ◽  
Author(s):  
R. L. Armstrong ◽  
S. M. Blumenfeld ◽  
C. G. Gray
Keyword(s):  
Correlation Functions ◽  
Theoretical Calculations ◽  
Dominant Contribution ◽  
Dispersion Interactions ◽  
Fundamental Vibration ◽  
Order Of Magnitude ◽  
The Mean ◽  
Vibration Rotation ◽  
Experimental Values ◽  
Rotational Correlation

Extensive measurements of the methane ν3 and ν4 fundamental vibration–rotation bands in CH4–He mixtures and the ν3 band in CH4–He, CH4–N2, and CD4–He mixtures have been carried out in infrared absorption at 295 °K to pressures of 3000 atm. Some profiles of the ν3 band in CH4–Ar mixtures and in pure CH4 have also been obtained. Rotational correlation functions, band moments, and intermolecular mean squared torques have been determined from the ν3 band profiles. Theoretical calculations of the mean squared torque due to anisotropic multipolar, induction and dispersion interactions have been carried out. The theoretical and experimental torques are in order-of-magnitude agreement for the CH4–N2 and CH4–CH4 systems; for CH4–He, CD4–He, and CH4–Ar the theoretical values are two to three orders of magnitude too small to account for the experimental values, indicating that in these cases the dominant contribution to the torques is given by the anisotropic overlap forces.

Study of the Mechanisms of Vortex Variability in the Lofoten Basin Based on the Energy Analysis

2021 ◽  
Vol 37 (3) ◽  
Author(s):  
V. S. Travkin ◽  
◽  
T. V. Belonenko ◽  
Keyword(s):  
Kinetic Energy ◽  
Potential Energy ◽  
Baroclinic Instability ◽  
Positive Trend ◽  
Barotropic Instability ◽  
Available Potential Energy ◽  
Conversion Rates ◽  
Order Of Magnitude ◽  
The Mean ◽  
Mean Kinetic Energy

Purpose. The Lofoten Basin is one of the most energetic zones of the World Ocean characterized by high activity of mesoscale eddies. The study is aimed at analyzing different components of general energy in the basin, namely the mean kinetic and vortex kinetic energy calculated using the integral of the volume of available potential and kinetic energy of the Lofoten Vortex, as well as variability of these characteristics. Methods and Results. GLORYS12V1 reanalysis data for the period 2010–2018 were used. The mean kinetic energy and the eddy kinetic one were analyzed; and as for the Lofoten Vortex, its volume available potential and kinetic energy were studied. The mesoscale activity of eddies in winter is higher than in summer. Evolution of the available potential energy and kinetic energy of the Lofoten Vortex up to the 1000 m horizon was studied. It is shown that the vortex available potential energy exceeds the kinetic one by an order of magnitude, and there is a positive trend with the coefficient 0,23⋅1015 J/year. It was found that in the Lofoten Basin, the intermediate layer from 600 to 900 m made the largest contribution to the potential energy, whereas the 0–400 m layer – to kinetic energy. The conversion rates of the mean kinetic energy into the vortex kinetic one and the mean available potential energy into the vortex available potential one (barotropic and baroclinic instability) were analyzed. It is shown that the first type of transformation dominates in summer, while the second one is characterized by its increase in winter. Conclusions. The vertical profile shows that the kinetic energy of eddies in winter is higher than in summer. The available potential energy of a vortex is by an order of magnitude greater than the kinetic energy. An increase in the available potential energy is confirmed by a significant positive trend and by a decrease in the vortex Burger number. The graphs of the barotropic instability conversion rate demonstrate the multidirectional flows in the vortex zone with the dipole structure observed in a winter period, and the tripole one – in summer. The barotropic instability highest intensity is observed in summer. The baroclinic instability is characterized by intensification of the regime in winter that is associated with weakening of stratification in this period owing to winter convection.

Numerical Simulation of Wave Breaking Over a Submerged Step with SPH Method

2018 ◽  
Vol 01 (02) ◽  
pp. 1840005 ◽  
Author(s):  
Hongjie Wen ◽  
Bing Ren ◽  
Guoyu Wang ◽  
Yumeng Zhao
Keyword(s):  
Wave Breaking ◽  
Sph Method ◽  
Vertical Distributions ◽  
Sph Model ◽  
Smoothed Particle ◽  
Mean Water Level ◽  
The Mean ◽  
Wave Maker ◽  
Wave Induced ◽  
Smoothed Particle Hydrodynamic

Wave breaking over a submerged step with a steep front slope and a wide horizontal platform is studied by smoothed particle hydrodynamic (SPH) method. By adding a momentum source term and a velocity attenuation term into the governing equation, a nonreflective wave maker system is introduced in the numerical model. A suitable circuit channel is specifically designed for the present SPH model to avoid the nonphysical rise of the mean water level on the horizontal platform of the submerged step. The predicted free surface elevations and the spatial distributions of wave height and wave setup over the submerged step are validated using the corresponding experimental data. In addition, the vertical distributions of wave-induced current over the submerged step are also investigated at both low and high tides.

scholarly journals Thermal Diffusion of Isotopes in Pure Liquids

1966 ◽  
Vol 21 (9) ◽  
pp. 1348-1351
Author(s):  
A. Lodding
Keyword(s):  
Mass Flow ◽  
Liquid Metals ◽  
Density Fluctuations ◽  
Pure Liquid ◽  
Theoretical Treatment ◽  
Liquid Model ◽  
Order Of Magnitude ◽  
Mean Size ◽  
The Mean ◽  
Effective Cluster

A theoretical treatment is given of the recently discovered thermotransport effect in pure liquid metals. The isotope effect is related to the diffusive mass flow by a proportionality factor familiar from electrotransport. The mass flow is given primarily by the temperature dependence of the mean size or amount of density fluctuations in the liquid. Very little activation energy is required for diffusive motion, which takes place by cooperative position adjustments of neighbor atoms. The mean displacement length of the diffusing cluster is by an order of magnitude smaller than the effective cluster diameter. The liquid model suggested is coherent with models based on evidence from other experimental methods.

How effective is KRM-1648 in treatment of disseminated Mycobacterium avium complex infections in beige mice?

1996 ◽  
Vol 40 (2) ◽  
pp. 437-442 ◽  
Author(s):  
B Ji ◽  
N Lounis ◽  
C Truffot-Pernot ◽  
J Grosset
Keyword(s):  
Mycobacterium Avium ◽  
Mycobacterium Avium Complex ◽  
Antimicrobial Effect ◽  
Bacteriostatic Effect ◽  
Dose Selection ◽  
Order Of Magnitude ◽  
The Mean ◽  
Resistant Mutants ◽  
Selection Of

Although the MICs of 3'-hydroxy-5'-(4-isobutyl-1-piperazinyl)benzoxazinorifamycin, or KRM-1648 (KRM), for Mycobacterium avium complex (MAC) were significantly lower than those of other drugs, its in vivo activity was very weak. Beginning 28 days after inoculation, beige mice that had been infected intravenously with 1.87 x 10(7) CFU of MAC 101 were administered KRM alone, clarithromycin (CLARI) alone, or CLARI plus KRM six times weekly for 16 weeks. In contrast to the mice treated with CLARI-containing regimens, the mortality and the mean spleen weights of mice treated with KRM alone (either 10 or 20 mg/kg of body weight per dose) did not differ significantly from those of untreated mice, their numbers of CFU were very much greater than pretreatment values, and multiplication of MAC was only slightly inhibited. Although monotherapy by KRM selected KRM-resistant mutants, the selection was very weak; the mean number of CFU and the frequency of KRM-resistant mutants increased by no more than 1 order of magnitude after 16 weeks of treatment with KRM at 20 mg/kg per dose. Selection of CLARI-resistant mutants was inhibited but not completely prevented by treatment of the mice with CLARI plus KRM. These results indicate that KRM displayed only a weak bacteriostatic effect against the isolate tested in the beige mouse model; its ability to enhance the antimicrobial effect of CLARI or to prevent emergence of CLARI-resistant mutants was very limited.

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