Cross Helicity of the November 2018 Magnetic Cloud Observed by the Parker Solar Probe

Magnetic clouds are large-scale transient structures in the solar wind with low plasma $\beta$, low-amplitude magnetic field fluctuations, and twisted field lines with both ends often connected to the Sun. Their inertial-range turbulent properties have not been examined in detail. In this Letter, we analyze the normalized cross helicity, $\sigma_c$, and residual energy, $\sigma_r$, of plasma fluctuations in the November 2018 magnetic cloud observed at 0.25 au by the Parker Solar Probe. A low value of $|\sigma_c|$ was present in the cloud core, indicating that wave power parallel and anti-parallel to the mean field was approximately balanced, while the cloud's outer layers displayed larger amplitude Alfv\'enic fluctuations with high $|\sigma_c|$ values and $\sigma_r\sim0$. These properties are discussed in terms of the cloud's solar connectivity and local interaction with the solar wind. We suggest that low $|\sigma_c|$ is likely a common feature of magnetic clouds given their typically closed field structure. Anti-sunward fluctuations propagating immediately upstream of the cloud had strongly negative $\sigma_r$ values.Comment: 9 pages, 4 figures; accepted for publication in the Astrophysical Journal Letters 2020 August 1

The Association of Early Dietary Supplementation with Vitamin E with the Incidence of Ulcerative Dermatitis in Mice on a C57BL/6 Background

The purpose of this study was to ascertain if prophylactic ingestion of a diet rich in vitamin E would prevent  or impede the development of ulcerative dermatitis in mice on a C57BL/6 background. Mice were fed after  weaning a standard mouse diet, vitamin E (99 IU/kg), or a mouse diet fortified with vitamin E (3000 IU/  kg). Cases of ulcerative dermatitis were recorded by individuals (i.e. aware of) the diet assignment. The  incidence of ulcerative dermatitis in a retrospective cohort of mice on standard diet was compared with the  group on the diet fortified with vitamin E. Age was associated with ulcerative dermatitis in standard diet  and vitamin E fortified diet groups, r = 0.43, p-value < 0.0001 and r = 0.18, p-value < 0.02, respectively.  The average age of incidence for ulcerative dermatitis in the mice fed the standard diet was 89 weeks and  for the mice fed the vitamin E diet it was 41 weeks. The unadjusted odds ratio comparing the incidence of  ulcerative dermatitis between the two diet groups was 4.6 with a 95% confidence interval of (2.44, 8.58),  x2 p-value < 0.0001. Therefore, there was an association between the diets and ulcerative dermatitis, with  the mice on the vitamin E fortified diet having almost five times the odds of having ulcerative dermatitis  compared with mice on the standard diet. Incidence of ulcerative dermatitis was not influenced by sex or  genotype. Our study results show that a diet fortified in vitamin E initiated at weaning does not prevent or  impede the development of ulcerative dermatitis in mice on a C57BL/6 background and on the contrary  accelerate development when administered to young mice.

On the Brightness and Waiting-time Distributions of a Type III Radio Storm observed by STEREO/WAVES

Type III solar radio storms, observed at frequencies below approximately 16 MHz by space borne radio experiments, correspond to the quasi-continuous, bursty emission of electron beams onto open field lines above active regions. The mechanisms by which a storm can persist in some cases for more than a solar rotation whilst exhibiting considerable radio activity are poorly understood. To address this issue, the statistical properties of a type III storm observed by the STEREO/WAVES radio experiment are presented, examining both the brightness distribution and (for the first time) the waiting-time distribution. Single power law behavior is observed in the number distribution as a function of brightness; the power law index is approximately 2.1 and is largely independent of frequency. The waiting-time distribution is found to be consistent with a piecewise-constant Poisson process. This indicates that during the storm individual type III bursts occur independently and suggests that the storm dynamics are consistent with avalanche type behavior in the underlying active region.Comment: 14 pages, 4 figures, 1 table. Accepted for publication in Astrophysical Journal Letter

Excavations and the afterlife of a professional football stadium, Peel Park, Accrington, Lancashire: towards an archaeology of football

Association football is now a multi-billion dollar global industry whose emergence spans the post-medieval to the modern world. With its professional roots in late 19th-century industrial Lancashire, stadiums built for the professionalization of football first appear in frequency in the North of England. While many historians of sport focus on consumerism and ‘topophilia’ (attachment to place) regarding these local football grounds, archaeological research that has been conducted on the spectator experience suggests status differentiation within them. Our excavations at Peel Park confirm this impression while also showing a significant afterlife to this stadium, particularly through children’s play

Structure and fluctuations of a slow ICME sheath observed at 0.5 au by the Parker Solar Probe

Context. Sheath regions ahead of interplanetary coronal mass ejections (ICMEs) are compressed and turbulent global heliospheric structures. Their global and fine-scale structure are outstanding research problems, and only a few studies have been conducted on this topic closer to the Sun than 1 au. Comprehensive knowledge of the sheath structure and embedded fluctuations and of their evolution in interplanetary space is important for understanding their geoeffectiveness, their role in accelerating charged particles to high energies, the interaction of ICMEs with the ambient wind, and the transport of energy between boundaries. Aims. Our key aims are to investigate in detail the overall structure, as well as nature (stochastic, chaotic, or periodic) and origin, of magnetic fluctuations within a sheath ahead of a slow ICME in the inner heliosphere. Methods. We used magnetic field and plasma observations from the Parker Solar Probe (PSP) during a sheath region observed at similar to 0.5 au on March 15, 2019, ahead of a slow and slowly expanding streamer blow-out CME bracketed between a slower and faster stream. To examine the magnetohydrodynamic-scale turbulent properties, we present an analysis of the fluctuation amplitudes, magnetic compressibility of fluctuations, partial variance of increments (PVI), normalised cross helicity (sigma(c)), and normalised residual energy (sigma(r)). We also conducted a Jensen-Shannon permutation entropy and complexity analysis. Results. The investigated sheath consisted of slower and faster flows that were separated by a brief (similar to 15 min) change in the magnetic sector bounded by current sheet crossings and a velocity shear zone. The fluctuation amplitudes and frequency of high PVI values were larger and higher throughout the sheath than in the upstream wind and had dominantly negative sigma(r) and strongly positive sigma(c). The velocity shear region marked a strong increase in temperature and specific entropy, and the following faster flow had large local patches of positive sigma(r) as well as larger fluctuation amplitudes and higher PVI values, in particular at smaller timescales. Fluctuations in the preceding wind and in the sheath were found to be stochastic. However, sheath fluctuations showed lower entropy and higher complexity, with entropy showing a reducing and complexity an increasing trend with increasing time lag. Conclusions. The two-part sheath structure was likely a result of a warp in the heliospheric current sheet (HCS) that was swept up and compressed into the sheath. The driving ejecta accelerated and heated the wind at the back of the sheath, which then interacted with the slower wind ahead of the HCS warp. This also caused some distinct differences in fluctuation properties across the sheath. Sheaths of slow ICMEs originating as streamer blow-outs can thus have complex structure where fluctuation properties are not just downstream shock properties, but are generated within the sheath. At short timescales, fluctuations feature fully developed and imbalanced MHD turbulence, while at longer scales, fluctuations are increasingly dominated by intermittent coherent and ordered structures.Peer reviewe

Eventscapes and the creation of event legacies

Attention is directed to the difference in event legacies created by mega-events which often cause dramatic physical changes in urban environments and those which accompany events which leave very little imprint on the landscape where they are held. The Tour Down Under cycle race, which is held annually in South Australia, is examined as an example of the latter. The spatial pattern of the event and the range of settings which support it are presented as an eventscape by drawing on concepts such as Bale's [1994. Landscapes of Modern Sport. Leicester: Leicester University Press] sportscape and Bitner's [1992. “Servicescapes: The Impact of Physical Surroundings on Customers and Employees.” The Journal of Marketing 56 (2): 57–71] servicescape. These interpretations are used to identify legacies. It is suggested that the creation of positive legacies requires communities that are part of the eventscape to engage in imaginative leveraging that is consistent with long-term strategic objectives. The paper offers a new definition of eventscape

Observing Solar Radio Bursts from the Lunar Surface

Locating low frequency radio observatories on the lunar surface has a number of advantages. Here, we describe the Radio Observatory for Lunar Sortie Science (ROLSS), a concept for a low frequency, radio imaging interferometric array designed to study particle acceleration in the corona and inner heliosphere. ROLSS would be deployed during an early lunar sortie or by a robotic rover as part of an unmanned landing. The prime science mission is to image type II and type III solar radio bursts with the aim of determining the sites at and mechanisms by which the radiating particles are accelerated. Secondary science goals include constraining the density of the lunar ionosphere by searching for a low radio frequency cutoff of the solar radio emissions and constraining the low energy electron population in astrophysical sources. Furthermore, ROLSS serves a pathfinder function for larger lunar radio arrays. Key design requirements on ROLES include the operational frequency and angular resolution. The electron densities in the solar corona and inner heliosphere are such that the relevant emission occurs below 10 MHz, essentially unobservable from Earth's surface due to the terrestrial ionospheric cutoff. Resolving the potential sites of particle acceleration requires an instrument with an angular resolution of at least 2 deg, equivalent to a linear array size of approximately 500 meters. Operations would consist of data acquisition during the lunar day, with regular data downlinks. The major components of the ROLSS array are 3 antenna arms arranged in a Y shape, with a central electronics package (CEP). Each antenna arm is a linear strip of polyimide film (e.g., Kapton (TM)) on which 16 single polarization dipole antennas are located by depositing a conductor (e.g., silver). The arms also contain transmission lines for carrying the radio signals from the science antennas to the CEP