A study on the response of Indian dip and low latitude ionospheric regions to a limb centred X9.0 class solar flare

In this paper, we present how Indian dip equatorial and low latitude ionospheric system responded to a limb centred X9.0 class of solar flare event using GPS-TEC, Ionosonde and magnetometer measurements. The limb centred X9.0 solar flare was materialise on 05 December 2006 at the heliography coordinate S07E68 and NOAA 10930 active region, started at 10:18 UT (15:48 IST), peaked at 10:35 UT (16:05 IST), and decayed by 10:45 UT (16:15 IST). The measurements of the total electron content (TEC) of 30 s time resolutions from a series of GPS receivers installed near the dip and low latitude regions does not show TEC enhancement during peak flare hours, 10:35 UT (16:05 IST). An appreciable enhancement in the TEC units (∼5 TEC units) is noticeable during post flare hours, 13:00 UT (18:30 IST) which is high at dip equatorial compare to low latitude regions. The Ionosonde measurement of 15 min time resolution at dip equatorial station shows an increase in the plasma density at the F-region while the E-region did not show any impact during peak flare hours, 10:35 UT (16:05 IST). The analysis of horizontal component of geomagnetic field (H) of 1 min time resolution data obtained from the INTERMAGNET shows sudden rise in electron density in the E-region of the ionosphere and intensification in the ionospheric current system in eastward direction at the dip equatorial and reverse in direction at low latitude regions at 10:35 UT (16:05 IST). Present analyses contribute our understanding about plasma dynamics during flare and post flare hours in the E and F-regions of Indian dip and low latitude Ionosphere

A facile approach to fabricate graphene based piezoresistive strain sensor on paper substrate

Sensors, FETs and chemi resistors are few of the devices which show potential in the area of flexible electronics for health monitoring applications. In the present work, piezoresistive strain sensors based on graphite and graphene on cellulose paper substrate has been reported. Graphite sensor has been fabricated by rubbing pencil on paper and graphene sensor by directly coating graphene ink using paint brush. The resistance of the fabricated sensor increases with outwards bending and vice-versa, further the piezoresistive effect has also been evaluated by applying variable longitudinal stress. A comparative study of gauge factor (GF) depending upon different type of strains has been presented and it has been observed that the GF of graphene piezoresistive strain sensor decreases with increase in number of layers, the GF for graphene sensor is higher as compared to graphite sensor. Fabricated piezoresistive strain sensors may find applications as human body motion detection, gait analysis etc

Combinatorial Effect of Fertigation Rate and Scheduling on Tomato Performance under Naturally Ventilated Polyhouse in Indian Humid Sub-Tropics

Protected cultivation is a resource-efficient method of crop production, however, at the same time, it is resource intensive. An optimum rate and time of fertilizer application is required in order to maximize crop yield vis-a-vis resource use efficiency. However, these aspects are scarcely studied for tomato under low- and medium-tech greenhouses in Indian humid sub-tropics. In this regard, a two-year study was conducted to assess the effect of four NPK fertilization rates (i.e., 120, 100, 80, and 60% of the recommended dose of fertilizers, RDF) and three fertigation scheduling approaches-fertigation at different stages in different proportions of NPK, along with an additional treatment, i.e., farmers' practice (soil-based application of recommended NPK) for tomatoes under a naturally ventilated polyhouse. The plant growth attributes, the tomato yield- and quality-related traits, the nutrient (NPK) accumulation by the plants, the water use efficiency (WUE), and economics were studied in response to different fertigation rates and scheduling approaches. These parameters were affected by both the rates of NPK fertilization and their time of application (scheduling) over the different growth stages. Among the different rates and time of fertigation, the recommended dose of fertilizer (100% RDF) (i.e., 300 kg N, 150 kg P2O5, and 150 kg K2O per ha and their scheduling as 15% N, 10% P2O5, and 10% K2O of RDF during 15-45 days after transplanting (P-1); 40% N, 40% P2O5, and 40% K2O of RDF during 47-76 DAT (P-2); 30% N, 40% P2O5, and 40% K2O of RDF during 77-107 DAT (P-3); and 15% N, 10% P2O5, and 10% K2O of RDF during 108-138 DAT (P-4)) was found to be the optimum for fruit yield, WUE, and economics of tomato under protected condition

Positional Disorder (Random Gaussian Phase Shifts) in the Fully Frustrated Josephson Junction Array (2D XY Model)

We consider the effect of positional disorder on a Josephson junction array with an applied magnetic field of f=1/2 flux quantum per unit cell. This is equivalent to the problem of random Gaussian phase shifts in the fully frustrated 2D XY model. Using simple analytical arguments and numerical simulations, we present evidence that the ground state vortex lattice of the pure model becomes disordered, in the thermodynamic limit, by any amount of positional disorder.Comment: 4 pages, 4 eps figures embedde

Micropropagation of Ilex khasiana, a critically endangered and endemic holly of Northeast India

The paper describes in vitro techniques for mass propagation of IIex khasiana, a rare and critically endangered holly endemic to Khasi Hills Hills of Meghalaya, India. The approach will help conserve I. khasiana and other endangered species

Ribosomal frameshifting and transcriptional slippage: From genetic steganography and cryptography to adventitious use.

Genetic decoding is not 'frozen' as was earlier thought, but dynamic. One facet of this is frameshifting that often results in synthesis of a C-terminal region encoded by a new frame. Ribosomal frameshifting is utilized for the synthesis of additional products, for regulatory purposes and for translational 'correction' of problem or 'savior' indels. Utilization for synthesis of additional products occurs prominently in the decoding of mobile chromosomal element and viral genomes. One class of regulatory frameshifting of stable chromosomal genes governs cellular polyamine levels from yeasts to humans. In many cases of productively utilized frameshifting, the proportion of ribosomes that frameshift at a shift-prone site is enhanced by specific nascent peptide or mRNA context features. Such mRNA signals, which can be 5' or 3' of the shift site or both, can act by pairing with ribosomal RNA or as stem loops or pseudoknots even with one component being 4 kb 3' from the shift site. Transcriptional realignment at slippage-prone sequences also generates productively utilized products encoded trans-frame with respect to the genomic sequence. This too can be enhanced by nucleic acid structure. Together with dynamic codon redefinition, frameshifting is one of the forms of recoding that enriches gene expression.This work was supported by grants from Science Foundation Ireland [12/IP/1492 and 13/1A/1853 to J.F.A; 12/IA/1335 to P.V.B.], US. National Institutes of Health [RO3 MH098688 to J.F.A.], the Wellcome Trust [106207 to A.E.F and 094423 to P.V.B.] and the European Research Council (ERC) grant No. 646891 to A.E.F.]This is the final version of the article. It first appeared from Oxford University Press via https://doi.org/10.1093/nar/gkw53

Constraints on Triton atmospheric evolution from occultations: 1989-2022

Context - Around the year 2000, Triton's south pole experienced an extreme summer solstice that occurs every about 650 years, when the subsolar latitude reached about 50{\deg}. Bracketing this epoch, a few occultations probed Triton's atmosphere in 1989, 1995, 1997, 2008 and 2017. A recent ground-based stellar occultation observed on 6 October 2022 provides a new measurement of Triton's atmospheric pressure which is presented here. Aims- The goal is to constrain the Volatile Transport Models (VTMs) of Triton's atmosphere that is basically in vapor pressure equilibrium with the nitrogen ice at its surface. Methods - Fits to the occultation light curves yield Triton's atmospheric pressure at the reference radius 1400 km, from which the surface pressure is induced. Results - The fits provide a pressure p_1400= 1.211 +/- 0.039 microbar at radius 1400 km (47 km altitude), from which a surface pressure of p_surf= 14.54 +/- 0.47 microbar is induced (1-sigma error bars). To within error bars, this is identical to the pressure derived from the previous occultation of 5 October 2017, p_1400 = 1.18 +/- 0.03 microbar and p_surf= 14.1 +/- 0.4 microbar, respectively. Based on recent models of Triton's volatile cycles, the overall evolution over the last 30 years of the surface pressure is consistent with N2 condensation taking place in the northern hemisphere. However, models typically predict a steady decrease in surface pressure for the period 2005-2060, which is not confirmed by this observation. Complex surface-atmosphere interactions, such as ice albedo runaway and formation of local N2 frosts in the equatorial regions of Triton could explain the relatively constant pressure between 2017 and 2022.Comment: 8 pages, 4 figures, accepted for publication in Astronomy and Astrophysic

Structural basis of ribosomal frameshifting

Versatility in genetic decoding enriches gene expression. Programmed shifting of the reading frame during translation is a prominent feature productively utilized in probably all life forms. While the occurrences, function, and mechanistic components have been identified for many instances of frameshifting, structural understanding of their basis at the atomic level has been limited to the individual components in isolation. Here, I present atomic level information of the decoding apparatus relevant to both -1 and +1 frameshifting. The +1 frameshifting event investigated is that of a sensor and effector of an autoregulatory circuit present in the common ancestor between yeast and humans. In regulating intracellular polyamine levels, the mammalian antizyme 2 frameshifting studied interacts with ornithine decarboxylase and c-myc. The polyamine spermidine is shown here to be present proximal to but not interfering with the peptidyl transferase center, making stabilizing interactions with the terminal phosphate of the P-site tRNA. Spermidine occupancy at this location is inferred to preclude binding of the translation factor eIF5A by occlusion of its hypusine moiety. Visualization of the nascent chain reveals a network of interactions with key residues of the peptide exit tunnel that gate the transit of the growing polypeptide. The -1 frameshifting event investigated is that required by SARS-CoV-2, the causative virus of the COVID-19 pandemic. The downstream RNA element that stimulates frameshifting is seen to adopt a corkscrew-shaped 3-stemmed pseudoknot structure that lodges itself at the entrance of the ribosomal mRNA channel. Distinct functional interactions of the nascent chain with the ribosome exit tunnel are observed while the distal end of the nascent peptide begins to undergo co-translational folding into a zinc finger motif. The study highlights the frameshift-inhibitory properties of Merafloxacin, a small molecule that inhibits propagation of SARS-CoV-2