[en] In this work, it is described the present stage of development of the Laboratorio de Metrologia Nuclear of IPEN, the measuring systems, the measurable activities range and the radionuclides already standardized. (A.C.A.S.)

[en] The latitude distribution of active regions with respect to the toroidal roll pattern has been investigated for the period 1978-1982. It is shown that the sunspot activity is not concentrated only at the boundaries of rolls. The ''downdraft'', at the convergence of adjacent rolls is however, more favourable than the ''updraft'' to the magnetic flux expulsion. The roll motions are probably not the hydrodynamic forces controlling the flux emergence. They, however, influence the magnetic complexity of the active regions, each torus acting as a selective amplifier

[en] W.S. Watson acknowledges the careful work of S.B. Samat et al (1997) in assessing the activity of the naturally occurring potassium radioisotope, ⁴⁰K in one gram of potassium and makes some comments on the accuracy of total body potassium (TBK) measurements. The reply by S.B. Samat et al to W.S. Watson's comments is also given. Letter-to-the-editor

[en] Background. Regular physical activity in childhood and adolescent plays an important role in reducing the risk of cardiovascular health diseases, diabetes, and obesity in adulthood. However, little is known about physical activity levels (PA) and sedentary time among children and adolescents in Morocco. Objective. To examine gender, type of day, and age grade differences in objectively measured sedentary time, physical activity levels, and physical activity guideline attainment among children and adolescents in Morocco. Method. 172 children/adolescents (mean age = 10.92 ± 1.55 years, 49.4% are boys) were recruited for this study and wore a tri-axial accelerometer (GT3X+) for 7 consecutive days. Time spent in sedentary, PA levels, and daily steps were measured and compared according to gender, age grade, and the type of day (weekdays/weekends). Results. In weekdays children/adolescents spent more time in sedentary than weekends (p < 0.001). Boys were eight times more likely to meet the recommendation for at least 60 min of moderate to vigorous physical activity per day than girls (OR: 8.569; 95% [CI]: 4.23–17.32), p < 0.001. Conclusion. These findings highlight the need for effective and sustainable strategies and programs aiming to promote physical activity and to reduce sedentary behavior among children and adolescents in Morocco. (author)

[en] Using simulations, we examine the average velocity as a function of applied drift force for active matter particles moving through a random obstacle array. We find that for low drift force, there is an initial flow regime where the mobility increases linearly with drive, while for higher drift forces a regime of negative differential mobility appears in which the velocity decreases with increasing drive due to the trapping of active particles behind obstacles. A fully clogged regime exists at very high drift forces when all the particles are permanently trapped behind obstacles. We find for increasing activity that the overall mobility is nonmonotonic, with an enhancement of the mobility for small levels of activity and a decrease in mobility for large activity levels. We show how these effects evolve as a function of disk and obstacle density, active run length, drift force, and motor force. (paper)

[en] Using precise measurements of the helium D₃ line, we have searched for statistically significant variations in the strength of chromospheric activity in 13 early F-type stars and two late F-type stars. In two early F-type stars, we find short-term (hours to days) variability based on ∼25 observations over the course of a week. In an additional two cases we find significant differences between observations taken years apart, but we can most likely explain this apparent long-term variation as an artifact of probable short-term variations. The evidence suggests that pure rotational modulation of discrete active regions is not responsible for the short-term variations in the early F-type stars and that either a more global process is at work or we are seeing large number of small active regions spread across the star. In contrast, the two late F-type stars in the sample show strength and/or wavelength variations that are consistent with 'solar-type' activity typified by the rotational modulation of active regions. Our results suggest that variability does not cause the wide range in activity levels observed within the early F-type stars.

[en] Indoor radon levels are normally higher than the corresponding outdoors levels to reduced ventilation rates indoors. The present work was conducted to examine the enhancement in indoor Rn levels, that might result from improvement of dwelling sealings, (intended to save energy) in typical Israeli housing. (author)

[en] Quantification accuracy and partial volume effect (PVE) of the Siemens Inveon PET scanner were evaluated. The influence of transmission source activities (40 and 160 MBq) on the quantification accuracy and the PVE were determined. Dynamic range, object size and PVE for different sphere sizes, contrast ratios and positions in the field of view (FOV) were evaluated. The acquired data were reconstructed using different algorithms and correction methods. The activity level of the transmission source and the total emission activity in the FOV strongly influenced the attenuation maps. Reconstruction algorithms, correction methods, object size and location within the FOV had a strong influence on the PVE in all configurations. All evaluated parameters potentially influence the quantification accuracy. Hence, all protocols should be kept constant during a study to allow a comparison between different scans. (paper)

No abstract available

[en] Abstract only