Simulations of the Kelvin-Helmholtz instability driven by coronal mass ejections in the turbulent corona

Recent high resolution AIA/SDO images show evidence of the development of the Kelvin-Helmholtz instability, as coronal mass ejections (CMEs) expand in the ambient corona. A large-scale magnetic field mostly tangential to the interface is inferred, both on the CME and on the background sides. However, the magnetic field component along the shear flow is not strong enough to quench the instability. There is also observational evidence that the ambient corona is in a turbulent regime, and therefore the criteria for the development of the instability are a-priori expected to differ from the laminar case. To study the evolution of the Kelvin-Helmholtz instability with a turbulent background, we perform three-dimensional simulations of the incompressible magnetohydrodynamic equations. The instability is driven by a velocity profile tangential to the CME-corona interface, which we simulate through a hyperbolic tangent profile. The turbulent background is generated by the application of a stationary stirring force. We compute the instability growth-rate for different values of the turbulence intensity, and find that the role of turbulence is to attenuate the growth. The fact that the Kelvin-Helmholtz instability is observed, sets an upper limit to the correlation length of the coronal background turbulence

Using deuterated PAH amendments to validate chemical extraction methods to predict PAH bioavailability in soils

Validating chemical methods to predict bioavailable fractions of polycyclic aromatic hydrocarbons (PAHs) by comparison with accumulation bioassays is problematic. Concentrations accumulated in soil organisms not only depend on the bioavailable fraction but also on contaminant properties. A historically contaminated soil was freshly spiked with deuterated PAHs (dPAHs). dPAHs have a similar fate to their respective undeuterated analogues, so chemical methods that give good indications of bioavailability should extract the fresh more readily available dPAHs and historic more recalcitrant PAHs in similar proportions to those in which they are accumulated in the tissues of test organisms. Cyclodextrin and butanol extractions predicted the bioavailable fraction for earthworms (Eisenia fetida) and plants (Lolium multiflorum) better than the exhaustive extraction. The PAHs accumulated by earthworms had a larger dPAH:PAH ratio than that predicted by chemical methods. The isotope ratio method described here provides an effective way of evaluating other chemical methods to predict bioavailability

Facing the future: strategies and investment behaviour of polish farmers

This paper analyses farm-household strategies and investment behaviour of Polish farmers with a particular focus on the perceived effects of CAP. The paper is based on a survey of Polish farmers carried out in 2006 on a sample of 63 farms. Farmers where selected in order to fit in the intersection of the following categories: different altitudes (plain/mountain); different specialisation (arable crops, livestock, fruit trees), different technology (conventional, organic). The survey includes information about farm and household structure, expectations, reaction to planned and intended investment, as well as about potential reforms such as decoupling of EU payments. Results show multifaceted expectations toward the future. The main objectives expressed by farmers are to reduce income uncertainty and to increase household worth. CAP payments are normally used on farm and concentrated on covering current costs and investment expenditure. The perspective of decoupling is expected to produce either no change or an increase of on farm investment.Common Agricultural Policy (CAP), Single Farm Payment (SFP), decoupling, impact analysis, Poland, investment behaviour., Agricultural Finance, Farm Management,

An Asymptotically-Optimal Sampling-Based Algorithm for Bi-directional Motion Planning

Bi-directional search is a widely used strategy to increase the success and convergence rates of sampling-based motion planning algorithms. Yet, few results are available that merge both bi-directional search and asymptotic optimality into existing optimal planners, such as PRM*, RRT*, and FMT*. The objective of this paper is to fill this gap. Specifically, this paper presents a bi-directional, sampling-based, asymptotically-optimal algorithm named Bi-directional FMT* (BFMT*) that extends the Fast Marching Tree (FMT*) algorithm to bi-directional search while preserving its key properties, chiefly lazy search and asymptotic optimality through convergence in probability. BFMT* performs a two-source, lazy dynamic programming recursion over a set of randomly-drawn samples, correspondingly generating two search trees: one in cost-to-come space from the initial configuration and another in cost-to-go space from the goal configuration. Numerical experiments illustrate the advantages of BFMT* over its unidirectional counterpart, as well as a number of other state-of-the-art planners.Comment: Accepted to the 2015 IEEE Intelligent Robotics and Systems Conference in Hamburg, Germany. This submission represents the long version of the conference manuscript, with additional proof details (Section IV) regarding the asymptotic optimality of the BFMT* algorith

Tunneling magnetic force microscopy

We have developed a powerful new tool for studying the magnetic patterns on magnetic recording media. This was accomplished by modifying a conventional scanning tunneling microscope. The fine-wire probe that is used to image surface topography was replaced with a flexible magnetic probe. Images obtained with these probes reveal both the surface topography and the magnetic structure. We have made a thorough theoretical analysis of the interaction between the probe and the magnetic fields emanating from a typical recorded surface. Quantitative data about the constituent magnetic fields can then be obtained. We have employed these techniques in studies of two of the most important issues of magnetic record: data overwrite and maximizing data-density. These studies have shown: (1) overwritten data can be retrieved under certain conditions; and (2) improvements in data-density will require new magnetic materials. In the course of these studies we have developed new techniques to analyze magnetic fields of recorded media. These studies are both theoretical and experimental and combined with the use of our magnetic force scanning tunneling microscope should lead to further breakthroughs in the field of magnetic recording

Effect of 13-cis-Retinoic Acid on the Hamster Flank Organ

Administration of 13-cis-retinoic acid subcutaneously to mature male hamsters produced a marked decrease in the size of the sebaceous glands of the flank organ, without diminution of other hormonally dependent structures of the flank organs. Subcutaneous administration of 13-cis-retinoic acid to female hamsters treated simultaneously with injections of testosterone enanthate prevented the androgen-induced growth of the flank organ sebaceous glands but did not prevent the growth of other hormonally dependent structures such as the dermal pigment cells and large pigmented hair follicles. The sebaceous gland progressively decreased during 3weeks of treatment and the effect persisted at least 3weeks after cessation of treatment but was completely reversed by 6 mos after treatment. In vitro studies of testosterone metabolism by hamster flank organ indicated the lack of inhibition of 5a-reduction by 13-cis-retinoic acid. It seems likely that systemically administered 13-cis-retinoic acid, unlike antiandrogens, exerts a specific extrahormonal effect on the sebaceous glands of the hamster flank organ without affecting other androgen dependent cells

Metabolism of Testosterone-4- 14C by Hamster Skin and Flank Organ**From the Department of Dermatology, Skin and Cancer unit, Mount Sinai Medical Center, Miami Beach, Florida, 33140

The metabolism of testosterone-4-14C by hamster skin and flank organ was studied; flank organ metabolized more testostrone than an equal weight of adjacent skin. Androstenedione,† androsterone, androstanedione, dihydrotestosterone (DHT), and 3α-androstanediol were identified by chromatography and reverse isotopic dilution as metabolites formed by flank organ. The metabolites of flank organ and general body skin showed identical chromatographic mobilities. Flank organ produced 4 times as much DHT as an equal weight of adjacent skin. The ratio of total 5α-metabolites formed by both tissues was the same as the DHT ratio, indicating that the greater amount of DHT formed is due to greater formation of 5α-metabolites, in general. In contrast, both tissues produced the same amount of 17-ketosteroids from testosterone and had similar DNA contents, suggesting that the observed difference in 5α-reduction was not due to differences in cellularity but to a greater capacity of the flank organ to reduce testosterone. No 3β-hydroxysteroids, the formation of which has been reported in human skin were found

Fathers report experiencing negative feelings and psychological difficulties during the perinatal period

The perinatal period is the time from the start of pregnancy to 1 year after the child has been born.1 During the perinatal period, an estimated 5%–10% of fathers will develop above-threshold symptoms of paternal depression.2 During this period, fathers can experience a high level of stress which can have negative effects on themselves and their families.3 This review aims to explore the needs and experiences associated with the mental health of fathers during this perinatal period.

Influence of length of day (photoperiod) on development of the soybean plant, var. Biloxi

Publication authorized July 1, 1936.Digitized 2007 AES.Includes bibliographical references (page 28)