Energetic ion dynamics in Jupiter's plasma sheet

A systematic study of energetic ion trajectories in Jupiter's plasma sheet region predicts a significant role for both regular and stochastic types of motion and reveals several aspects of the ion dynamics that aid in the interpretation of Galileo observations. The motion is generally confined to the vicinity of the current sheet in a way that is proportional to the variable current sheet thickness as seen in the particle and field data. The radial extent of the trajectories increases with rigidity and initial radial distance from the planet, explaining the corresponding lack of high-rigidity ions and decreasing radial gradients at lower rigidity. Ion intensity increases associated with changes in current sheet thickness suggest an acceleration region at ∼25 to 30 R_J. Energy dispersion in ion events at larger radial distances can be explained by such a source combined with elastic ion scattering

Apomixis: an enigma with potential applications

Apomixis has been the focus of research in plant sciences in recent years with lot of scope for crop improvement. It results in clonal progeny without fertilization, having maternal genetic constitution. The impact of introducing apomixis in crop plants could be significant mainly for its use in fixation of hybrid vigour. Because of epigenetic barriers, introgression of apomixis from a close relative to a sexual crop plant by conventional plant breeding methods could not generate expected results. Recent developments in plant molecular biology and biotechnology can help in developing potential strategies. This article summarizes various aspects of apomixis research that are being followed in India and abroad

Floral induction in a photoperiodically insensitive duckweed, Lemna paucicostata LP6

The effects of 20 amino acids and two amides were studied on the flowering of a photoperiodically insensitive duckweed, Lemna paucicostata LP6. Alanine, asparagine, aspartate, cystine, glutamate, glutamine, glycine, lysine, methionine, proline, serine, and threonine induced flowering under a photoperiodic regime of 16 hours light and 8 hours darkness. Among these, glutamate and aspartate were found to be the most effective for flower induction. These acids could initiate flowering even at 5×10-7 molar level, though maximal flowering (about 80%) was obtained at 10-5 molar. Change in the photoperiodic schedule or the pH of the nutrient medium did not influence glutamate- or aspartate-induced flowering. The low concentrations at which glutamate and aspartate are effective suggests that they may have a regulatory role rather than simply acting as metabolites

Searching for Galactic White Dwarf Binaries in Mock LISA Data using an F-Statistic Template Bank

We describe an F-statistic search for continuous gravitational waves from galactic white-dwarf binaries in simulated LISA Data. Our search method employs a hierarchical template-grid based exploration of the parameter space. In the first stage, candidate sources are identified in searches using different simulated laser signal combinations (known as TDI variables). Since each source generates a primary maximum near its true "Doppler parameters" (intrinsic frequency and sky position) as well as numerous secondary maxima of the F-statistic in Doppler parameter space, a search for multiple sources needs to distinguish between true signals and secondary maxima associated with other, "louder" signals. Our method does this by applying a coincidence test to reject candidates which are not found at nearby parameter space positions in searches using each of the three TDI variables. For signals surviving the coincidence test, we perform a fully coherent search over a refined parameter grid to provide an accurate parameter estimation for the final candidates. Suitably tuned, the pipeline is able to extract 1989 true signals with only 5 false alarms. The use of the rigid adiabatic approximation allows recovery of signal parameters with errors comparable to statistical expectations, although there is still some systematic excess with respect to statistical errors expected from Gaussian noise. An experimental iterative pipeline with seven rounds of signal subtraction and re-analysis of the residuals allows us to increase the number of signals recovered to a total of 3419 with 29 false alarms.Comment: 29 pages, 11 figures; submitted to Classical and Quantum Gravit

Phytochrome modulation of calcium fluxes in wheat (Triticum aestivum L.) protoplasts

Employing the metallochromic dye murexide and by monitoring the uptake of radiolabelled calcium, photoreversible calcium fluxes were measured in wheat leaf protoplast suspensions. Results obtained by both methods were identical - red light promoted and subsequent far-red irradiation reversed an influx of Ca++ ions into the protoplasts. These findings imply phytochrome regulation of Ca++ fluxes across the plasma membrane. The influx of Ca++ stimulated by 2 min red irradiation could be maintained in total darkness for the initial 16-18 min after illumination, after which a 6-8 min efflux process was triggered and the basal Ca++ level restored. Verapamil, a calcium channel blocker, inhibited the red-promoted influx, whereas the far-red mediated efflux could be checked by the use of the ATPase inhibitor vanadate, and also by the calmodulin antagonist chlorpromazine, thus suggesting a role of ion channels and pumps in phytochrome-controlled Ca++ fluxes. The possible involvement of phosphoinositides in phytochrome-modulated calcium fluxes was also investigated

Analyzing a higher order q(t)q(t) model and its implications in the late evolution of the Universe using recent observational datasets

In this research paper, we explore a well-motivated parametrization of the time-dependent deceleration parameter, characterized by a cubic form, within the context of late time cosmic acceleration. The current analysis is based on the $f(Q,T)$ gravity theory, by considering the background metric as the homogeneous and isotropic Friedmann Lema\^itre Robertson Walker (FLRW) metric. Investigating the model reveals intriguing features of the late universe. To constrain the model, we use the recent observational datasets, including cosmic chronometer (CC), Supernovae (SNIa), Baryon Acoustic Oscillation (BAO), Cosmic Microwave Background Radiation (CMB), Gamma Ray Burst (GRB), and Quasar (Q) datasets. The joint analysis of these datasets results in tighter constraints for the model parameters, enabling us to discuss both the physical and geometrical aspects of the model. Moreover, we determine the present values of the deceleration parameter ($q_0$), the Hubble parameter ($H_0$), and the transition redshift ($z_t$) from deceleration to acceleration ensuring consistency with some recent results of Planck 2018. Our statistical analysis yields highly improved results, surpassing those obtained in previous investigations. Overall, this study presents valuable insights into the higher order $q(t)$ model and its implications for late-time cosmic acceleration, shedding light on the nature of the late universe

Double Perovskite Sr2FeMoO6: A Potential Candidate for Room Temperature Magnetoresistance Device Applications

The family of double perovskites first received attention in the 1960s, but the discovery of low field magnetoresistnace (LFMR) and half metallicity of the Sr2FeMoO6 (SFMO) compound was made by Kobayashi et al. in 1998. A fully spin polarized half-metal SFMO (Tc > 400) with excellent magnetoresistance response relatively at small applied fields and high temperatures makes SFMO an ideal candidate for room temperature spintronics applications. Primarily, most of the research work on double perovskites SFMO has been focused on bulk ceramic samples and aimed to understand their structural, magnetic, and magnetotransport properties, along with correlation among them. A material such as SFMO that exhibits a large decrease in resistivity and magnetically order well above room temperature is necessary for the advancement of spintronic devices. If the bulk properties observed could be reproduced in thin films, industrially produced SFMO-based spintronic devices could become a reality. Therefore, the purpose of this chapter is to present the detailed background and descriptions of the double perovskite Sr2FeMoO6 (SFMO) thin films and heterostructures with main emphasis to improve or achieve room temperature magnetoresistance properties especially for room temperature magnetoresistive device applications