Additional experimental evidence for a solar influence on nuclear decay rates

Additional experimental evidence is presented in support of the recent hypothesis that a possible solar influence could explain fluctuations observed in the measured decay rates of some isotopes. These data were obtained during routine weekly calibrations of an instrument used for radiological safety at The Ohio State University Research Reactor using Cl-36. The detector system used was based on a Geiger-Mueller gas detector, which is a robust detector system with very low susceptibility to environmental changes. A clear annual variation is evident in the data, with a maximum relative count rate observed in January/February, and a minimum relative count rate observed in July/August, for seven successive years from July 2005 to June 2011. This annual variation is not likely to have arisen from changes in the detector surroundings, as we show here.Comment: 8 pages, 6 figure

Combined analysis of solar neutrino and solar irradiance data: further evidence for variability of the solar neutrino flux and its implications concerning the solar core

A search for any particular feature in any single solar neutrino dataset is unlikely to establish variability of the solar neutrino flux since the count rates are very low. It helps to combine datasets, and in this article we examine data from both the Homestake and GALLEX experiments. These show evidence of modulation with a frequency of 11.85 yr-1, which could be indicative of rotational modulation originating in the solar core. We find that precisely the same frequency is prominent in power spectrum analyses of the ACRIM irradiance data for both the Homestake and GALLEX time intervals. These results suggest that the solar core is inhomogeneous and rotates with sidereal frequency 12.85 yr-1. We find, by Monte Carlo calculations, that the probability that the neutrino data would by chance match the irradiance data in this way is only 2 parts in 10,000. This rotation rate is significantly lower than that of the inner radiative zone (13.97 yr-1) as recently inferred from analysis of Super-Kamiokande data, suggesting that there may be a second, inner tachocline separating the core from the radiative zone. This opens up the possibility that there may be an inner dynamo that could produce a strong internal magnetic field and a second solar cycle.Comment: 22 pages, 9 tables, 10 figure

Physical Constraints in Grassland Ecosystems

Key points 1. Grassland system management must account adequately for biophysical and biochemical processes. 2. Amenity turf, especially sports turf, provides an excellent case study on how biology and physics interact to impact on the functioning of a grass ecosystem. 3. Microorganisms produce hydrophobic compounds that act to decrease water ingress and alter the function of the soil-grass ecosystem

Study of the relationship between solar activity and terrestrial weather

Evidence for some connection between weather and solar related phenomena is presented. Historical data of world wide temperature variations with relationship to change in solar luminosity are examined. Several test methods for estimating the statistical significance of such phenomena are discussed in detail

A new look at a polar crown cavity as observed by SDO/AIA

Context. The Solar Dynamics Observatory (SDO) was launched in February 2010 and is now providing an unprecedented view of the solar activity at high spatial resolution and high cadence covering a broad range of temperature layers of the atmosphere. Aims. We aim at defining the structure of a polar crown cavity and describing its evolution during the erupting process. Methods. We use the high-cadence time series of SDO/AIA observations at 304 Å (50 000 K) and 171 Å (0.6 MK) to determine the structure of the polar crown cavity and its associated plasma, as well as the evolution of the cavity during the different phases of the eruption. We report on the observations recorded on 13 June 2010 located on the north-west limb. Results. We observe coronal plasma shaped by magnetic field lines with a negative curvature (U-shape) sitting at the bottom of a cavity. The cavity is located just above the polar crown filament material. We thus observe the inner part of the cavity above the filament as depicted in the classical three part coronal mass ejection (CME) model composed of a filament, a cavity, and a CME front. The filament (in this case a polar crown filament) is part of the cavity, and it makes a continuous structuring from the filament to the CME front depicted by concentric ellipses (in a 2D cartoon). Conclusions. We propose to define a polar crown cavity as a density depletion sitting above denser polar crown filament plasma drained down the cavity by gravity. As part of the polar crown filament, plasma at different temperatures (ranging from 50 000 K to 0.6 MK) is observed at the same location on the cavity dips and sustained by a competition between the gravity and the curvature of magnetic field lines. The eruption of the polar crown cavity as a solid body can be decomposed into two phases: a slow rise at a speed of 0.6 km s-1 and an acceleration phase at a mean speed of 25 km s-1

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

The Basics of Water Waves Theory for Analogue Gravity

This chapter gives an introduction to the connection between the physics of water waves and analogue gravity. Only a basic knowledge of fluid mechanics is assumed as a prerequisite.Comment: 36 pages. Lecture Notes for the IX SIGRAV School on "Analogue Gravity", Como (Italy), May 201

Solar Physics - Plasma Physics Workshop

A summary of the proceedings of a conference whose purpose was to explore plasma physics problems which arise in the study of solar physics is provided. Sessions were concerned with specific questions including the following: (1) whether the solar plasma is thermal or non-themal; (2) what spectroscopic data is required; (3) what types of magnetic field structures exist; (4) whether magnetohydrodynamic instabilities occur; (5) whether resistive or non-magnetohydrodynamic instabilities occur; (6) what mechanisms of particle acceleration have been proposed; and (7) what information is available concerning shock waves. Very few questions were answered categorically but, for each question, there was discussion concerning the observational evidence, theoretical analyses, and existing or potential laboratory and numerical experiments

Fast and slow two-fluid magnetic reconnection

We present a two-fluid magnetohydrodynamics (MHD) model of quasi-stationary, two-dimensional magnetic reconnection in an incompressible plasma composed of electrons and ions. We find two distinct regimes of slow and fast reconnection. The presence of these two regimes can provide a possible explanation for the initial slow build up and subsequent rapid release of magnetic energy frequently observed in cosmic and laboratory plasmas.Comment: 16 pages, 2 figures, 1 tabl

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