Comparative Analysis of Super-Kamiokande and SNO Solar-Neutrino Data and the Photospheric Magnetic Field

We analyze Super-Kamiokande, SNO, and photospheric magnetic-field data for the common time interval, namely the SNO D2O phase. Concerning rotational modulation, the magnetic-field power spectrum shows the strongest peaks at the second and sixth harmonics of the solar synodic rotation frequency [3 nu(rot) and 7 nu(rot)]. The restricted Super-Kamiokande dataset shows strong modulation at the second harmonic. The SNO D2O dataset shows weak modulation at that frequency, but strong modulation in the sixth-harmonic frequency band. We estimate the significance level of the correspondence of the Super-Kamiokande second-harmonic peak with the corresponding magnetic-field peak to be 0.0004, and the significance level of the correspondence of the SNO D2O sixth-harmonic peak with the corresponding magnetic-field peak to be 0.009. By estimating the amplitude of the modulation of the solar neutrino flux at the second harmonic from the restricted Super-Kamiokande dataset, we find that the weak power at that frequency in the SNO D2O power spectrum is not particularly surprising. Concerning 9.43 yr-1, we find no peak at this frequency in the power spectrum formed from the restricted Super-Kamiokande dataset, so it is no surprise that this peak does not show up in the SNO D2O dataset, either.Comment: 32 pages, 8 tables, 16 figure

Just by being here, you aren’t halfway there:structured active learning and its integration in virtual learning environments and assessment

Flipped learning with the incorporation of certain elements of gamification aims to improve student engagement, motivation and attainment. In this study we present an analysis of two approaches used in consecutive years on two modules. A traditional flipped learning approach “standard learning” where material is released weekly online and there are supporting tutorials and an end of term assessment; and a “structured active learning” strategy where a more scaffolded approach is applied, requiring participation to progress. In this approach students’ work on the virtual learning environment and in tutorials could be used to contribute towards their end of term assessment (no more than 10% of the module credit), connected to a learning outcome on the breadth or range of topics. Students received feedback in rubric form throughout the topic, to see their progression. It was found that for module 1, over 90% of the students had accessed the pre-released material by week 2 in the structured active learning approach while this level of engagement was only reached in week 5 using the standard approach. Participation in learning events was far better using the structured active learning approach when compared to the standard approach, for example rising from 40% to 78% in week 2. The second module, with a different cohort of students, followed similar trends with the active learning approach attracting higher levels of engagement and participation far earlier in the term. Following the increased engagement, the structured active learning approach was beneficial in assessment with improved grade profiles

Power Spectrum Analysis of Physikalisch-Technische Bundesanstalt Decay-Rate Data: Evidence for Solar Rotational Modulation

Evidence for an anomalous annual periodicity in certain nuclear decay data has led to speculation concerning a possible solar influence on nuclear processes. We have recently analyzed data concerning the decay rates of Cl-36 and Si-32, acquired at the Brookhaven National Laboratory (BNL), to search for evidence that might be indicative of a process involving solar rotation. Smoothing of the power spectrum by weighted-running-mean analysis leads to a significant peak at frequency 11.18/yr, which is lower than the equatorial synodic rotation rates of the convection and radiative zones. This article concerns measurements of the decay rates of Ra-226 acquired at the Physikalisch-Technische Bundesanstalt (PTB) in Germany. We find that a similar (but not identical) analysis yields a significant peak in the PTB dataset at frequency 11.21/yr, and a peak in the BNL dataset at 11.25/yr. The change in the BNL result is not significant since the uncertainties in the BNL and PTB analyses are estimated to be 0.13/yr and 0.07/yr, respectively. Combining the two running means by forming the joint power statistic leads to a highly significant peak at frequency 11.23/yr. We comment briefly on the possible implications of these results for solar physics and for particle physics.Comment: 15 pages, 13 figure

Concerning the Phases of Annual Variations of Nuclear Decay Rates

Recent analyses of datasets acquired at the Brookhaven National Laboratory and at the Physikalisch-Technische Bundesanstalt both show evidence of pronounced annual variations, suggestive of a solar influence. However, the phases of decay-rate maxima do not correspond precisely to the phase of minimum Sun-Earth distance, as might then be expected. We here examine the hypothesis that decay rates are influenced by an unknown solar radiation, but that the intensity of the radiation is influenced not only by the variation in Sun-Earth distance, but also by a possible North-South asymmetry in the solar emission mechanism. We find that this can lead to phases of decay-rate maxima in the range 0 to 0.183 or 0.683 to 1 (September 6 to March 8) but that, according to this hypothesis, phases in the range 0.183 to 0.683 (March 8 to September 6) are "forbidden." We find that phases of the three datasets here analyzed fall in the allowed range.Comment: 5 Pages, 5 Figure

Two Gallium data sets, spin flavour precession and KamLAND

We reexamine the possibility of a time modulation of the low energy solar neutrino flux which is suggested by the average decrease of the Ga data in line with our previous arguments. We perform two separate fits to the solar neutrino data, one corresponding to 'high' and the other to 'low' Ga data, associated with low and high solar activity respectively. We therefore consider an alternative to the conventional solar+KamLAND fitting, which allows one to explore the much wider range of the $\theta_{12}$ angle permitted by the KamLAND fitting alone. We find a solution with parameters $\Delta m^2_{21}=8.2\times 10^{-5} eV^2, tan^{2}\theta=0.31$ in which the 'high' and the 'low' Ga rates lie far apart and are close to their central values and is of comparable quality to the global best fit, where these rates lie much closer to each other. This is an indication that the best fit in which all solar and KamLAND data are used is not a good measure of the separation of the two Ga data sets, as the information from the low energy neutrino modulation is dissimulated in the wealth of data. Furthermore for the parameter set proposed one obtains an equally good fit to the KamLAND energy spectrum and an even better fit than the 'conventional' LMA one for the reactor antineutrino survival probability as measured by KamLAND.Comment: V2: 15 pages, 3 eps figures, fit improved, final version to appear in Journal of Physics

Power-spectrum analysis of Super-Kamiokande solar neutrino data, taking into account asymmetry in the error estimates

The purpose of this article is to carry out a power-spectrum analysis (based on likelihood methods) of the Super-Kamiokande 5-day dataset that takes account of the asymmetry in the error estimates. Whereas the likelihood analysis involves a linear optimization procedure for symmetrical error estimates, it involves a nonlinear optimization procedure for asymmetrical error estimates. We find that for most frequencies there is little difference between the power spectra derived from analyses of symmetrized error estimates and from asymmetrical error estimates. However, this proves not to be the case for the principal peak in the power spectra, which is found at 9.43 yr-1. A likelihood analysis which allows for a "floating offset" and takes account of the start time and end time of each bin and of the flux estimate and the symmetrized error estimate leads to a power of 11.24 for this peak. A Monte Carlo analysis shows that there is a chance of only 1% of finding a peak this big or bigger in the frequency band 1 - 36 yr-1 (the widest band that avoids artificial peaks). On the other hand, an analysis that takes account of the error asymmetry leads to a peak with power 13.24 at that frequency. A Monte Carlo analysis shows that there is a chance of only 0.1% of finding a peak this big or bigger in that frequency band 1 - 36 yr-1. From this perspective, power spectrum analysis that takes account of asymmetry of the error estimates gives evidence for variability that is significant at the 99.9% level. We comment briefly on an apparent discrepancy between power spectrum analyses of the Super-Kamiokande and SNO solar neutrino experiments.Comment: 13 pages, 2 tables, 6 figure

High-resolution 3D phenotyping of the grapevine root system using X-ray Computed Tomography

Plant roots are essential for water and nutrient uptake and contribute to the plants' response to environmental stress factors. As the hidden half of a plant, investigation of root systems is highly challenging, most of available methods are destructive and very labour-intensive. In this proof-of-concept study, a non-invasive X-ray micro computed tomography (X-ray µCT) method was applied to investigate the phenotypic variation of the complex three-dimensional (3D) architecture of grapevine roots as a function of genotype and soil. Woody cuttings of 'Calardis Musqué', 'Villard Blanc' and V3125 ('Schiava Grossa' x 'Riesling') were cultivated in polypropylene columns filled with two different soil types, clay loam and sandy loam, for 6 weeks. Afterwards, the columns were scanned once using the technique of X-ray µCT. The received raw data were analysed for the reconstruction of 3D root system models (3D model), which display a non-destructive visualization of whole, intact root systems with a spatial resolution of 42 µm. The 3D models of all investigated plants (in total 18) were applied to quantify root system characteristics precisely by measuring adventitious root length, lateral root length, total root length, root system surface area, root system volume and root growth angles from the woody cutting relative to a horizontal axis. The results showed that: (i) early root formation and root growth differed between genotypes, especially between 'Calardis Musqué' and 'Villard Blanc'; and (ii) the soil type does influence adventitious root formation of V3125, but had minor effects on 'Calardis Musqué' and 'Villard Blanc'. In conclusion, this innovative, high-resolution method of X-ray µCT is suitable for high resolution phenotyping of root formation, architecture, and rooting characteristics of grapevine woody cuttings in a non-destructive manner, e.g. to investigate root response to drought stress and would provide new insights into phylloxera root infection

Electromagnetic showers in a strong magnetic field

We present the results concerning the main shower characteristics in a strong magnetic field obtained through shower simulation. The processes of magnetic bremsstrahlung and pair production were taken into account for values of the parameter $\chi \gg 1$. We compare our simulation results with a recently developed cascade theory in a strong magnetic field.Comment: 11 pages, 9 eps figures, LaTex2e, Iopart.cls, Iopart12.clo, Iopams.st

Search for correlation between geomagnetic disturbances and mortality

Statistical evaluation of death rates in the U.S.A. from heart diseases or stroke did not show any correlation with measured geomagnetic pulsations and thus do not support a claimed relationship between geomagnetic activity and mortality rates to low frequency fluctuations of the earth's magnetic field