Radial evolution of sunward strahl electrons in the inner heliosphere

The heliospheric magnetic field (HMF) exhibits local inversions, in which the field apparently “bends back” upon itself. Candidate mechanisms to produce these inversions include various configurations of upstream interchange reconnection; either in the heliosphere, or in the corona where the solar wind is formed. Explaining the source of these inversions, and how they evolve in time and space, is thus an important step towards explaining the origins of the solar wind. Inverted heliospheric magnetic field lines can be identified by the anomalous sunward (i.e. inward) streaming of the typically anti-sunward propagating, field aligned (or anti-aligned), beam of electrons known as the “strahl”. We test if the pitch angle distribution (PAD) properties of sunward-propagating strahl are different from those of outward strahl.We perform a statistical study of strahl observed by the Helios spacecraft, over heliocentric distances spanning ≈ 0.3 – 1 AU. We find that sunward strahl PADs are broader and less intense than their outward directed counterparts; particularly at distances 0.3 – 0.75 AU. This is consistent with sunward strahl being subject to additional, path-length dependent, scattering in comparison to outward strahl.We conclude that the longer and more variable path from the Sun to the spacecraft, along inverted magnetic field, leads to this additional scattering. The results also suggest that the relative importance of scattering along this additional path length drops off with heliocentric distance. These results can be explained by a relatively simple, constant-rate, scattering process

IPM Implementation Project - Continuing Using NEWA Internet Resources To Increase Use of Onion IPM

Growers on 5 onion farms received a review on how to access information from NEWA and they were assisted in incorporating NEWA disease and weather forecasts, as well as field scouting, into their crop protection decision-making process. The wet season and significant disease pressure were motivating factors in their use of the onion disease and weather forecasts. The Modified Blight Alert and the Michigan Botrytis Forecast numbers were impressive and the growers took the disease pressure seriously. One of the 5 growers never participated in an onion IPM program before

Using NEWA Internet Resources To Increase Use of Onion IPM

Growers on 5 onion farms were taught how to access information from NEWA and 4 were assisted in incorporating NEWA disease and weather forecasts, as well as field scouting, into their crop protection decision-making process. This helped them fine-tune their pesticide applications and to reduce the risks of crop loss from pests. It is expected that they would make more use of NEWA in a year with normal/excess rainfall. Two of the 4 growers never participated in an onion IPM program before

The DSM-5: hyperbole, hope or hypothesis?

The furore preceding the release of the new edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) is in contrast to the incremental changes to several diagnostic categories, which are derived from new research since its predecessor’s birth in 1990. While many of these changes are indeed controversial, they do reflect the intrinsic ambiguity of the extant literature. Additionally, this may be a mirror of the frustration of the field’s limited progress, especially given the false hopes at the dawn of the “decade of the brain”. In the absence of a coherent pathophysiology, the DSM remains no more than a set of consensus based operationalized adjectives, albeit with some degree of reliability. It does not cleave nature at its joints, nor does it aim to, but neither does alternate systems. The largest problem with the DSM system is how it’s used; sometimes too loosely by clinicians, and too rigidly by regulators, insurers, lawyers and at times researchers, who afford it reference and deference disproportionate to its overt acknowledged limitations

Simulations of a lattice model of two-headed linear amphiphiles: influence of amphiphile asymmetry

Using a 2D lattice model, we conduct Monte Carlo simulations of micellar aggregation of linear-chain amphiphiles having two solvophilic head groups. In the context of this simple model, we quantify how the amphiphile architecture influences the critical micelle concentration (CMC), with a particular focus on the role of the asymmetry of the amphiphile structure. Accordingly, we study all possible arrangements of the head groups along amphiphile chains of fixed length $N=12$ and 16 molecular units. This set of idealized amphiphile architectures approximates many cases of symmetric and asymmetric gemini surfactants, double-headed surfactants and boloform surfactants. Consistent with earlier results, we find that the number of spacer units $s$ separating the heads has a significant influence on the CMC, with the CMC increasing with $s$ for $s<N/2$. In comparison, the influence of the asymmetry of the chain architecture on the CMC is much weaker, as is also found experimentally.Comment: 30 pages, 17 fgure

The evolution of inverted magnetic fields through the inner heliosphere

Local inversions are often observed in the heliospheric magnetic field (HMF), but their origins and evolution are not yet fully understood.Parker Solar Probe has recently observed rapid, Alfvénic, HMF inversions in the inner heliosphere, known as ‘switchbacks’, which have been interpreted as the possible remnants of coronal jets. It has also been suggested that inverted HMF may be produced by near-Sun interchange reconnection; a key process in mechanisms proposed for slow solar wind release. These cases suggest that the source of inverted HMF is near the Sun, and it follows that these inversions would gradually decay and straighten as they propagate out through the heliosphere. Alternatively, HMF inversions could form during solar wind transit, through phenomena such velocity shears, draping over ejecta, or waves and turbulence. Such processes are expected to lead to a qualitatively radial evolution of inverted HMF structures. Using Helios measurements spanning 0.3–1 AU, we examine the occurrence rate of inverted HMF, as well as other magnetic field morphologies, as a function of radial distance r, and find that it continually increases. This trend may be explained by inverted HMF observed between 0.3–1 AU being primarily driven by one or more of the above in-transit processes, rather than created at the Sun. We make suggestions as to the relative importance of these different processes based on the evolution of the magnetic field properties associated with inverted HMF. We also explore alternative explanations outside of our suggested driving processes which may lead to the observed trend

Generation of inverted heliospheric magnetic flux by coronal loop opening and slow solar wind release

In situ spacecraft observations provide much-needed constraints on theories of solar wind formation and release, particularly the highly variable slow solar wind, which dominates near-Earth space. Previous studies have shown an association between local inversions in the heliospheric magnetic field (HMF) and solar wind released from the vicinity of magnetically closed coronal structures. We here show that in situ properties of inverted HMF are consistent with the same hot coronal source regions as the slow solar wind. We propose that inverted HMF is produced by solar wind speed shear, which results from interchange reconnection between a coronal loop and open flux tube, and introduces a pattern of fast–slow–fast wind along a given HMF flux tube. This same loop-opening process is thought to be central to slow solar wind formation. The upcoming Parker Solar Probe and Solar Orbiter missions provide a unique opportunity to directly observe these processes and thus determine the origin of the slow solar wind

Development of a Basement Membrane Substitute Incorporated Into an Electrospun Scaffold for 3D Skin Tissue Engineering

yesA major challenge in the production of 3D tissue engineered skin is the recreation of the basement membrane region to promote secure attachment and yet segregation of keratinocytes from the dermal substitute impregnated with fibroblasts. We have previously shown that simple electrospun scaffolds provide fibres on which the cells attach, proliferate, and self-sort into epithelium and dermis. In a development of this in this study tri-layered scaffolds were then electrospun from poly L-lactic acid and poly hydroxybutyrate-co-hydroxyvalerate. In these a central layer of the scaffolds comprising nano-porous/nano-fibrous poly hydroxybutyrate-co-hydroxyvalerate fibres was interwoven into the bulk micro-porous poly L-lactic acid microfibers to mimic the basement membrane. Keratinocytes and fibroblasts seeded onto these scaffolds and cultured for 2 weeks showed that neither cell type was able to cross the central nano-porous barrier (shown by SEM, and fluorescence monitoring with CellTracker™) while the micro-fibrous poly L-lactic acid provided a scaffold on which keratinocytes could create an epithelium and fibroblasts could create a dermal substitute depositing collagen. Although cells did not penetrate this barrier the interaction of cells was still evident-essential for epithelial development