Enhanced metabolite yield with compensatory biomass reduction revealed by moisture stress induction in Centella asiatica (L.)

The exposure to any kind of stress tends to accelerate the secondary metabolism in medicinal plants increasing the production of secondary metabolites. The present investigation was undertaken to study the effect of moisture stress (100, 75, 50, 25 and 10% pot capacity) and control (as without plant) on growth, yield and metabolite content of Centella asiatica var. ‘Arka Prabhavi’, for two growing seasons under polyhouse conditions. Results revealed that moisture stress treatments had a significant effect on all observed growth and yield traits. Plants maintained at 100% PC exhibited luxurious vegetative growth with maximum leaf length (6.28 cm), leaf breadth (8.14 cm), petiole length (22.32 cm) and fresh biomass yield (164 g/pot). Cumulative water transpired and water use efficiency of the plants was also observed to be maximum at 100% PC. In contrary to biomass yield, increased asiaticoside (1.864%, 1.892%), madecassoside (2.856%, 3.382%) and total triterpenoid content (5.356%, 5.578%) at higher moisture stress levels of 75% and 50% PC, respectively, was observed. Hence, it is appropriate to grow Centella either at 100% or 75% PC to get optimum biomass and metabolite yield on a commercial scale

Robust seed selection algorithm for k-means type algorithms

Selection of initial seeds greatly affects the quality of the clusters and in k-means type algorithms. Most of the seed selection methods result different results in different independent runs. We propose a single, optimal, outlier insensitive seed selection algorithm for k-means type algorithms as extension to k-means++. The experimental results on synthetic, real and on microarray data sets demonstrated that effectiveness of the new algorithm in producing the clustering resultsComment: 17 pages, 5 tables, 9figure

Genetic Evaluation of Leucaena Genotypes in Bundelkhand Region of Central India

During the 1970s and 1980s, Leucaena was known as the “miracle tree” native to Central America and Mexico, because of its worldwide success as a long-lived and highly nutritious forage tree. It is estimated to cover 2-5 million ha area worldwide. The genus Leucaena is one of the most widely grown tropical fodder trees and is the subject of extensive research. This is mainly due to its long life span; high productivity even under regular defoliation; its adaptation to wide climatic and edaphic tolerances; excellent palatability and digestibility and many uses including wood for timber and fuel wood. The species possesses enormous wealth of variability and great potential for economic yield which attract the breeders in utilizing the species in hybridization. A logical way to start any breeding programme is to survey the variations present in the germplasm. Precise information on the nature and degree of genetic divergence in respect of important traits is a prerequisite for undertaking meaningful breeding programme towards the improvement and conservation of a species. Further an investigation into the nature and degree of divergence among populations will be useful in understanding the course of evolution and for classifying the tree population into groups based on the diversity, particularly when they are overlapping in one more characters. Therefore, the present study was conducted to estimate genetic divergence among different germplasm of genus Leucaena

Synthesis and anti–microbial activity of 1,2,3–triazole tethered nitroguiacol ethers

Nitro aromatic/nitrophenols have been widely distributed in nature and are mostly isolated from marine microorganisms and had shown a broad spectrum of anti–microbial activities against a wide range of microbial pathogens. The objective of the present work is to Synthesize some new 1,2,3–triazole tethered nitroguiacol ethers and evaluated of their anti–bacterial and anti–fungal activities. A focused library of 1,2,3-triazole tethered nitroguiacol ethers were prepared by employing Cu (I) catalyzed click chemistry reaction and evaluated for their antimicrobial activities by broth microdilution method. Among the tested compounds, compounds 8e, 8f, 8g, and 8i exhibited broad–spectrum activity against selected pathogenic strains, with the MIC of 8 µg/mL for gram–positive bacteria (Staphylococcus aureus), 16 µg/mL for Pseudomonas aeruginosa (gram–negative bacteria), and Candida species, respectively. Future investigations with this class of compounds may lead to the development of potential candidates for antimicrobial drug discovery.Â

Transformations of morphine, codeine and their analogues by Bacillus sp.

749-75

Energy fluxes in helical magnetohydrodynamics and dynamo action

Renormalized viscosity, renormalized resistivity, and various energy fluxes are calculated for helical magnetohydrodynamics using perturbative field theory. The calculation is to first-order in perturbation. Kinetic and magnetic helicities do not affect the renormalized parameters, but they induce an inverse cascade of magnetic energy. The sources for the the large-scale magnetic field have been shown to be (1) energy flux from large-scale velocity field to large-scale magnetic field arising due to nonhelical interactions, and (2) inverse energy flux of magnetic energy caused by helical interactions. Based on our flux results, a premitive model for galactic dynamo has been constructed. Our calculations yields dynamo time-scale for a typical galaxy to be of the order of $10^8$ years. Our field-theoretic calculations also reveal that the flux of magnetic helicity is backward, consistent with the earlier observations based on absolute equilibrium theory.Comment: REVTEX4; A factor of 2 corrected in helicit

Outcome of pterygium surgery: analysis over 14 years

Aim: To report the outcome of pterygium surgery performed at a tertiary eye care centre in South India. Methods: Retrospective analysis of medical records of 920 patients (989 eyes) with primary and recurrent pterygia operated between January 1988 and December 2001. The demographic variables, surgical technique (bare sclera, primary closure, amniotic membrane transplantation (AMT), conjunctival autograft (CAG), conjunctival-limbal autograft (CLAG), or surgical adjuvants), recurrences and postoperative complications were analysed. Results: A total of 496 (53.9%) were male and 69 (7.5%) had bilateral pterygia. Bare sclera technique was performed in 267 (27.0%) eyes, primary conjunctival closure in 32 (3.2%), AMG in 123 (12.4%), CAG in 429 (43.4%), and CLAG in 70 (7.1%). Adjuvant mitomycin C was used in 44 (4.4%) cases. The mean duration of follow-up was 8.917.0 and 5.98.8 months for unilateral primary and recurrent pterygia, respectively. The overall recurrence rate was 178 (18.0%). Following primary and recurrent unilateral pterygium excision respectively, recurrences were noted in 46 (19.4%) and 1 (33.3%) eyes after bare sclera technique, five (16.7%) and 0 after primary closure, 28 (26.7%) and 0 with AMG, 42 (12.2%) and five (31.3%) with CAG, and nine (17.3%) and two (40%) with CLAG. Recurrences were significantly more in males with primary (23.3 vs10.7%, P<0.0001) and recurrent (26.7 vs0%, P=0.034) pterygia, and in those below 40 years (25.2 vs14.8%, P=0.003). Conclusion: CAG appears to be an effective modality for primary and recurrent pterygia. Males and patients below 40 years face greater risk of recurrence. Bare sclera technique has an unacceptably high recurrence. Prospective studies comparing CAG, CLAG, and AMG for primary and recurrent pterygia are needed

Non-linear microwave impedance of short and long Josephson Junctions

The non-linear dependence on applied $ac$ field ($b_{\omega}$) or current ($i_{\omega}$) of the microwave (ac) impedance $R_{\omega}+iX_{\omega}$ of both short and long Josephson junctions is calculated under a variety of excitation conditions. The dependence on the junction width is studied, for both field symmetric (current anti-symmetric) and field anti-symmetric (current symmetric) excitation configurations.The resistance shows step-like features every time a fluxon (soliton) enters the junction, with a corresponding phase slip seen in the reactance. For finite widths the interference of fluxons leads to some interesting effects which are described. Many of these calculated results are observed in microwave impedance measurements on intrinsic and fabricated Josephson junctions in the high temperature superconductors, and new effects are suggested. When a $$ field ($b_{dc}$) or current ($i_{dc}$) is applied, interesting phase locking effects are observed in the ac impedance $Z_{\omega}$. In particular an almost periodic dependence on the dc bias is seen similar to that observed in microwave experiments at very low dc field bias. These results are generic to all systems with a $\cos (\phi)$ potential in the overdamped limit and subjected to an ac drive.Comment: 7 pages, 11 figure

Magneto-electrodynamics at high frequencies in the antiferromagnetic and superconducting states of DyNi_2B_2C

We report the observation of novel behaviour in the radio frequency (rf) and microwave response of DyNi_2B_2C over a wide range of temperature (T) and magnetic field (H) in the antiferromagnetic (AFM) and superconducting (SC) states. At microwave frequencies of 10 GHz, the T dependence of the surface impedance Z_s=R_s+iX_s was measured which yields the T dependence of the complex conductivity \sigma_1-i\sigma_2 in the SC and AFM states. At radio frequencies (4 MHz), the H and T dependence of the penetration depth \lambda(T,H) were measured. The establishment of antiferromagnetic order at T_N=10.3 K results in a marked decrease in the scattering of charge carriers, leading to sharp decreases in R_s and X_s. However, R_s and X_s differ from each other in the AFM state. We show that the results are consistent with conductivity relaxation whence the scattering rate becomes comparable to the microwave frequency. The rf measurements yield a rich dependence of the scattering on the magnetic field near and below T_N. Anomalous decrease of scattering at moderate applied fields is observed at temperatures near and above T_N, and arises due to a crossover from a negative magnetoresistance state, possibly associated with a loss of spin disorder scattering at low fields, to a positive magnetoresistance state associated with the metallic nature. The normal state magnetoresistance is positive at all temperatures for \mu_0H>2T and at all fields for T>15K. Several characteristic field and temperature scales associated with metamagnetic transitions (H_M1(T), H_M2(T)) and onset of spin disorder H_D(T), in addition to T_c, T_N and H_c2(T) are observed in the rf measurements.Comment: 9 pages, Latex, Uses REVTeX, This and related publications also available at http://sagar.physics.neu.edu/ Submitted to Phys. Rev.

Studies on High Density Planting and Nutrient Requirement of Banana in Different States of India

An experiment was conducted under the ICAR-All India Coordinated Research Project on Fruits to study the high-density planting (HDP) and nutrient requirement of banana at six research centres across the country, including Bhubaneswar (Orissa), Gandevi (Gujarat), Jalgaon (Maharashtra), Jorhat (Assam), Kannara (Kerala) and Mohanpur (West Bengal) to enable higher productivity of banana and profit to farmers. The objective of this study was to explore the possibility of increasing productivity through the intervention of only per unit plant population (through planting system) and level of nutrition, but without any interference to the regional choices of variety (eg., choice variety Nendran for Kerala or Martaman for West Bengal), production system (mono/poly- clone, single/multi-year plantation, and POP of respective states), for which national productivity ranges are much skewed also. Results indicated that intervention of only plant density could increase the productivity of banana within the existing system of production and choice of a variety of different regions or states. The experiment was laid out in RBD with four planting densities (S1P2, S1P3, S2P2 and S2P3, where S1=2m x 3m, S2=1.8m x 3.6m, P2=2 suckers/hill, P3=3 suckers/hill), three nutrition levels (F1, F2 and F3 , which is 100%, 75% and 50% of RDF) and one with region-specific conventional planting density and nutrition (100% of RDF) practices as control. The results of this experiment showed that HDP (S1P3, 5000 plants /ha) in banana, accommodating three suckers per hill at 2m x 3m spacing increased productivity over the conventional system at the Bhubaneswar, Gandevi, Jorhat, Kannara and Mohanpur centres. The increase in productivity due to HDP (5,000/ha) over control was 28.9% (RDF 25%) to 50.6% (RDF 100%) at Bhubaneswar, 15.2% (RDF 25%) to 21.9% (RDF 100%) at Gandevi, 4.0% (RDF 25%) to 7.4% (RDF 100%) at Jorhat, 33.5% (RDF 25%) to 43.5% (RDF 100%) at Kannara and 46.5% (RDF 25%) to 79.0% (RDF 100%) at Mohanpur centre. The nutrient requirement under HDP was 100% RDF at Kannara, 75% RDF at Bhubaneswar and Mohanpur and 50% RDF at Gandevi and Jorhat centres, which indicates a saving in cost of fertilizer input by 25% -50%. It is, therefore, recommended for HDP (5000 plants/ha) in banana, accommodating three suckers per hill at 2m x 3m (6.6 ft x 3.8 ft) spacing with 50% RDF in the agro-climatic regions of Gandevi and Jorhat, with 75% RDF in the agro-climatic regions of Bhubaneswar and Mohanpur and with 100% RDF in the agro-climatic region of Kannara in order to ensure higher productivity and profit to farmers