Numerical simulation of helical jets at active region peripheries

ABSTRACT Coronal jets are observed above minority-polarity intrusions throughout the solar corona. Some of the most energetic ones occur on the periphery of active regions where the magnetic field is strongly inclined. These jets exhibit a non-radial propagation in the low corona as they follow the inclined field, and often have a broad, helical shape. We present a three-dimensional magnetohydrodynamic simulation of such an active-region-periphery helical jet. We consider an initially potential field with a bipolar flux distribution embedded in a highly inclined magnetic field, representative of the field nearby an active region. The flux of the minority polarity sits below a bald-patch separatrix initially. Surface motions are used to inject free energy into the closed field beneath the separatrix, forming a sigmoidal flux rope that eventually erupts producing a helical jet. We find that a null point replaces the bald patch early in the evolution and that the eruption results from a combination of magnetic breakout and an ideal kinking of the erupting flux rope. We discuss how the two mechanisms are coupled, and compare our results with previous simulations of coronal-hole jets. This comparison supports the hypothesis that the generic mechanism for all coronal jets is a coupling between breakout reconnection and an ideal instability. We further show that our results are in good qualitative and quantitative agreement with observations of active-region-periphery jets.

Evaluation of hair growth promoting activity of petroleum ether extract of Abrus precatorius Linn. on Wistar Albino rats

In present investigation was carried out to screening of hair growth promoting potentiality of petroleum ether extract of Abrus precatorius leaf. Preliminary chemical tests and TLC analysis revealed the presence flavonoids and saponins. Hair growth promoting activity of petroleum ether of Abrus precatorius was screened by considering different parameters which included time taken for covering bald patch, length of hair produced, percentage of hair follicles in anagen and telogen phases, time of hair growth initiation and completion and level of minerals in blood. The petroleum ether extract of Abrus precatorius showed a very good hair growth promoting activity at a dose of 300 mg/kg which was comparable to that of 2% minoxidil. After 30 days of treatment with test and standard drugs it was observed that, time taken for covering the bald patch, hair growth initiation and completion time and quantitative hair growth were found to be comparable to that of the standard drug. An increase in percentage of hair follicles turning from telogen phase to anagen phase was noted. The control treated group of animals showed poor hair growth for all the parameters. Keywords: Abrus precatorius Linn, Anagen, Catagen, Telogen, Minoxidil

PROSPECTIVE CLINICAL STUDY TO ASSESS THE SAFETY AND EFFICACY OF DRAVANTI BEEJ LEPA (LOCAL APPLICATION OF CROTON TIGLIUM) IN INDRALUPTA W. S. R. TO ALOPECIA AREATA

Indralupta (Alopecia Areata) is not life threatening disorder but it definitely affects the quality of life like impairing psychological well-being thus affecting mental and social status of person due to bald patch. It is characterized by smooth, circumscribed bald patch on the hair bearing area. The risk of allopathic treatment outweighs their benefits. Indralupta is considered under Kshudraroga by most of the authors of classical Ayurvedic texts. Safety and efficacy of Dravanti beeja lepa in regeneration of hair in Indralupta is assessed through present study. Prospective open randomized single-arm clinical trial was carried out on 30 patients showing classical symptoms of Indralupta. A Skin patch test has been done prior to apply the lepa for safety assessment. The Dravanti beeja lepa was given for local application twice a day over a period of 28 day. Indralupta was found to be more prevelant in males. Intake of Amla, Katu and lavana Rasa, non-vegetarian diet, stress factor and use of cosmetics could be considered as etiological factor of Indralupta. On regular use of Dravanti beeja lepa, regeneration of hair was also observed to significant level. Thus, Dravanti beeja lepa proved its safety and efficacy for topical application.

Effect of plateau pikas disturbance and patchiness on ecosystem carbon emission of alpine meadow on the northeastern part of Qinghai-Tibetan Plateau

Plateau pikas (Ochotona curzoniae) disturbance and patchiness intensify the spatial heterogeneous distribution of vegetation productivity and soil physicochemical properties, which may alter ecosystem carbon emission process. Nevertheless, previous researches have mostly focused on the homogeneous vegetation patches rather than heterogeneous underlying surface. Thus, this study aims to improve our understanding of the difference in ecosystem respiration (Re) over heterogeneous underlying surface at the plot scale in an alpine meadow grassland. Six different land surface: large bald patch, medium bald patch, small bald patch, intact grassland, above pika tunnel and pika pile were selected to analyze the response of Re to pikas disturbance and patchiness, and the key controlling factors. The results showed that (1) soil moisture (SM) under pika pile and bald patches was 2–11 % less than intact grassland despite pikas disturbance increased water infiltration rate, while soil temperature (ST) under pika pile and bald patches was 1–3 ℃ higher than intact grassland; (2) soil organic carbon (SOC) and total nitrogen (TN) density under above pika tunnel were 2.45–3.31 and 2.10–3.72 times higher than other surface types; and (3) Re under intact grassland and above pika tunnel were 0.22–1.07 times higher than pika pile and bald patches, and Re was significantly correlated with SM, TN and vegetation biomass (P

Topologically driven coronal dynamics – a mechanism for coronal hole jets

Bald patches are magnetic topologies in which the magnetic field is concave up over part of a photospheric polarity inversion line. A bald patch topology is believed to be the essential ingredient for filament channels and is often found in extrapolations of the observed photospheric field. Using an analytic source-surface model to calculate the magnetic topology of a small bipolar region embedded in a global magnetic dipole field, we demonstrate that although common in closed-field regions close to the solar equator, bald patches are unlikely to occur in the open-field topology of a coronal hole. Our results give rise to the following question: What happens to a bald patch topology when the surrounding field lines open up? This would be the case when a bald patch moves into a coronal hole, or when a coronal hole forms in an area that encompasses a bald patch. Our magnetostatic models show that, in this case, the bald patch topology almost invariably transforms into a null point topology with a spine and a fan. We argue that the time-dependent evolution of this scenario will be very dynamic since the change from a bald patch to null point topology cannot occur via a simple ideal evolution in the corona. We discuss the implications of these findings for recent Hinode XRT observations of coronal hole jets and give an outline of planned time-dependent 3-D MHD simulations to fully assess this scenario.