May 12 1997 Cme Event: I. a Simplified Model of the Pre-Eruptive Magnetic Structure

A simple model of the coronal magnetic field prior to the CME eruption on May 12 1997 is developed. First, the magnetic field is constructed by superimposing a large-scale background field and a localized bipolar field to model the active region (AR) in the current-free approximation. Second, this potential configuration is quasi-statically sheared by photospheric vortex motions applied to two flux concentrations of the AR. Third, the resulting force-free field is then evolved by canceling the photospheric magnetic flux with the help of an appropriate tangential electric field applied to the central part of the AR. To understand the structure of the modeled configuration, we use the field line mapping technique by generalizing it to spherical geometry. It is demonstrated that the initial potential configuration contains a hyperbolic flux tube (HFT) which is a union of two intersecting quasi-separatrix layers. This HFT provides a partition of the closed magnetic flux between the AR and the global solar magnetic field. The vortex motions applied to the AR interlock the field lines in the coronal volume to form additionally two new HFTs pinched into thin current layers. Reconnection in these current layers helps to redistribute the magnetic flux and current within the AR in the flux-cancellation phase. In this phase, a magnetic flux rope is formed together with a bald patch separatrix surface wrapping around the rope. Other important implications of the identified structural features of the modeled configuration are also discussed.Comment: 25 pages, 11 figures, to appear in ApJ 200

Paleolinguistics brings more light on the earliest history of the traditional Eurasian pulse crops

Traditional pulse crops such as pea, lentil, field bean, bitter vetch, chickpea and common vetch originate from Middle East, Mediterranean and Central Asia^1^. They were a part of human diets in hunter-gatherers communities^2^ and are one of the most ancient cultivated crops^3,4^. Europe has always been rich in languages^5^, with individual families still preserving common vocabularies related to agriculture^6,7^. The evidence on the early pulse history witnessed by the attested roots in diverse Eurasian proto-languages remains insufficiently clarified and its potential for supporting archaeobotanical findings is still non-assessed. Here we show that the paleolinguistic research may contribute to archaeobotany in understanding the role traditional Eurasian pulse crops had in the everyday life of ancient Europeans. It was found that the Proto-Indo-European language^8,9^ had the largest number of roots directly related to pulses, such as *arnk(')- (a leguminous plant), *bhabh- (field bean), *erəgw[h]- (a kernel of leguminous plant; pea), *ghArs- (a leguminous plant), *kek-, *k'ik'- (pea) and *lent- (lentil)^10,11,12^, numerous words subsequently related to pulses^13,14^ and borrowings from one branch to another^15^, confirming their essential place in the nutrition of Proto-Indo-Europeans^16,17,18^. It was also determined that pea was the most important among Proto-Uralic people^19,20,21^, while pea and lentil were the most significant in the agriculture of Proto-Altaic people^22,23,24^. Pea and bean were most common among Caucasians^25,26^, Basques^27,28^ and their hypothetical common forefathers^29^ and bean and lentil among the Afro-Asiatic ancestors of modern Maltese^30^. Our results demonstrate that pulses were common among the ancestors of present European nations and that paleolinguistics and its lexicological and etymological analysis may be useful in better understanding the earliest days of traditional Eurasian crops. We believe our results could be a basis for advanced multidisciplinary approach to the pulse crop domestication, involving plant scientists, archaeobotanists and linguists, and for reconstructing even earlier periods of pulse history

A novel metric for coronal MHD models

[1] In the interest of quantitatively assessing the capabilities of coronal MHD models, we have developed a metric that compares the structures of the white light corona observed with SOHO LASCO C2 to model predictions. The MAS model is compared to C2 observations from two Carrington rotations during solar cycle 23, CR1913 and CR1984, which were near the minimum and maximum of solar activity, respectively, for three radial heights, 2.5 R⊙, 3.0 R⊙, and 4.5 R⊙. In addition to simulated polarization brightness images, we create a synthetic image based on the field topology along the line of sight in the model. This open-closed brightness is also compared to LASCO C2 after renormalization. In general, the model\u27s magnetic structure is a closer match to observed coronal structures than the model\u27s density structure. This is expected from the simplified energy equations used in current global corona MHD models

Effect of Cutting Date on Quality of Red Clover Forage

Development stage or plant age is an important factor determining the chemical composition and quality of red clover forage (Ignjatovic et al., 2001). In early spring, young red clover plants have large leaf mass, high contents of moisture, protein and minerals and a low fibre content. In the course of the growing season, under the effects of long days and high temperatures, the plant undergoes morphological changes: leaves grow more slowly, the stem elongates, dry matter yield increases and quality drops, especially digestibility and the contents of protein and minerals

Observational properties of a kink unstable coronal loop

Aims. Previous work on the dynamics of the kink instability has concentrated on the evolution of the magnetic field and associated current sheets. Here we aim to determine the observational consequences of the kink instability in short coronal loops, particularly what images TRACE would record of such an instability. This paper concentrates on the internal m = 1 mode where the kink structure of the instability may not be apparent from the global field shape. This is most relevant to the observation of active region brightenings and coronal bright points. Methods. An existing fluid code was modified to include the TRACE temperature response function in order to calculate temporally and spatially averaged, line of sight images in the 171, 195 and 284 Å band passes for straight, kink unstable flux tubes. Results. Two new fluid effects of the kink instability are discovered: the circular enhancement of the density at the foot points and the appearance of a low density band running across the flux tube. The second of these effects is shown to be imagable by TRACE and hence would be a good candidate observational signature for an internal m = 1 kink unstable loop

The triggering of MHD instabilities through photospheric footpoint motions

The results of 3D numerical simulations modelling the twisting of a coronal loop due to photospheric vortex motions are presented. The simulations are carried out using an initial purely axial field and an initial equilibrium configuration with twist, . The non-linear and resistive evolutions of the instability are followed. The magnetic field is twisted by the boundary motions into a loop which initially has boundary layers near the photospheric boundaries as has been suggested by previous work. The boundary motions increase the twist in the loop until it becomes unstable. For both cases the boundary twisting triggers the kink instability. In both cases a helical current structure wraps itself around the kinked central current. This current scales linearly with grid resolution indicating current sheet formation. For the cases studied 35-40% of the free magnetic energy is released. This is sufficient to explain the energy released in a compact loop flare

Aerobic capacity and respiratory patterns are better in recreational basketball-engaged university students than age-matched untrained males

Study aim: To asses and compare the aerobic capacity and respiratory parameters in recreational basketball-engaged university students with age-matched untrained young adults. Material and methods: A total of 30 subjects were selected to took part in the study based on recreational-basketball activity level and were assigned to a basketball (BG: N = 15, age 22.86 ± 1.35 yrs., body height 185.07 ± 5.95 cm, body weight 81.21 ± 6.15 kg) and untrained group (UG: N = 15, age 22.60 ± 1.50 yrs., body height 181.53 ± 6.11 cm, body weight 76.89 ± 7.30 kg). Inspiratory vital capacity (IVC), forced expiration volume (FEV1), FEV1/IVC ratio, maximal oxygen consumption (VO2max), ventilatory threshold (VO2VT) and time to exhaustion, were measured in all subjects. Student T-test for independent Sample and Cohen's d as the measure of the effect size were calculated. Results: Recreational basketball-engaged students (EG) reached significantly greater IVC (t = 7.240, p < 0.001, d = 1.854), FEV1 (t = 10.852, p < 0.001, d = 2.834), FEV1/IVC ratio (t = 6.370, p < 0.001, d = 3.920), maximal oxygen consumption (t = 9.039, p < 0.001, d = 3.310), ventilatory threshold (t = 9.859, p < 0.001, d = 3.607) and time to exhaustion (t = 12.361, p < 0.001, d = 4.515) compared to UG. Conclusions: Long-term exposure to recreational basketball leads to adaptive changes in aerobic and respiratory parameters in male university students

Phase Field Model for Three-Dimensional Dendritic Growth with Fluid Flow

We study the effect of fluid flow on three-dimensional (3D) dendrite growth using a phase-field model on an adaptive finite element grid. In order to simulate 3D fluid flow, we use an averaging method for the flow problem coupled to the phase-field method and the Semi-Implicit Approximated Projection Method (SIAPM). We describe a parallel implementation for the algorithm, using Charm++ FEM framework, and demonstrate its efficiency. We introduce an improved method for extracting dendrite tip position and tip radius, facilitating accurate comparison to theory. We benchmark our results for two-dimensional (2D) dendrite growth with solvability theory and previous results, finding them to be in good agreement. The physics of dendritic growth with fluid flow in three dimensions is very different from that in two dimensions, and we discuss the origin of this behavior