2,496 research outputs found
Constraining the Variation in Fine-Structure Constant Using SDSS DR8 QSO Spectra
We report a robust constrain on the possible variation of fine-structure
constant, alpha = e^2/(hbar*c), obtained using O III 4959,5007, nebular
emission lines from QSOs. We find Delta-alpha/alpha=-(2.1 +/- 1.6) x 10^(-5)
based on a well selected sample of 2347 QSOs from Sloan Digital Sky Survey Data
Release 8 with 0.02 < z < 0.74. Our result is consistent with a non-varying
alpha at a level of 2 x 10^(-5) over approximately 7 Gyr. This is the largest
sample of extragalactic objects yet used to constrain the variation of alpha.
While this constraint is not as stringent as those determined using
many-multiplet method it is free from various systematic effects. A factor of ~
4 improvement in Delta-alpha/alpha achieved here compared to the previous study
(Bahcall et al. 2004) is just consistent with what is expected based on a
factor of 14 times bigger sample used here. This suggests that errors are
mainly dominated by the statistical uncertainty. We also find the ratio of
transition probabilities corresponding to the O III 5007 A and 4959 A lines to
be 2.933+/-0.002, in good agreement with the National Institute of Standards
and Technology measurements.Comment: 5 pages, 3 figures; Accepted for publication in MNRAS Lette
Asexual reproduction without a mycelial phase in Neurospora.
Asexual reproduction without a mycelial phase in Neurospora
REITs and Idiosyncratic Risk
This study examines various determinants of idiosyncratic risk from the perspective of un-diversified REIT investors, managers holding options, other option holders, and arbitrageurs. Since real estate investment trusts (REITs) enjoy a unique organizational structure and tax status, the relevant determinants derived from the two-stage regression model are different from other industrial firms. Results suggest that efficiency, liquidity and earnings variability are the important determinants of idiosyncratic risk, whereas size and capital do not
SOLID AS SOLVENTâ€- NOVEL SPECTROPHOTOMETRIC ANALYSIS OF NORFLOXACIN TABLETS USING PHENOL AS SOLVENT
Commonly used organic solvents for spectrophotometric analysis of water insoluble drugs include methanol, ethanol, chloroform, benzene, dichloromethane, dimethyl formamide, acetonitrile, ethyl acetate, toluene, carbon tetrachloride, acetone, hexane etc. The main drawbacks of organic solvents include high cost, toxicity and pollution. Organic solvents have innumerous adverse effects caused by single exposure like dermatitis, headache, drowsiness, nausea, eye irritation and long term exposure causes serious effects such as neurological disorders, chronic renal failure, liver damage, necrosis, mutagenesis disorder. They should be replaced by other eco-friendly alternative sources. The present investigation is an attempt to show that solids can also be wisely used to act as solvent precluding the use of organic solvents. In a separate study, author has attempted soxhelation using phenol as solvent. The vapours of boiling phenol got condensed in extraction chamber to effect the extraction of active constituents from powder of crude drugs. The main objective of the present study is to demonstrate the solvent action of solids. Solid excipients can nicely be employed as solubilizers in the development of pharmaceutical dosage forms in solution form of poorly soluble drugs (mixed solvency concept). Present study describes the application of solvent character of melted phenol (at 50-60°C) for spectroscopic estimation of norfloxacin tablets. Solubility of norfloxacin in distilled water is 0.88 mg/ml. More than 100 mg of nofloxacin dissolves in one gram of melted phenol (at 50-60°C). In the present investigation, melted phenol (at 50-60°C) was utilized to extract out (dissolve) the drug from powder of norfloxacin tablets. Distilled water was used for dilution purpose. Absorbances of standard solutions containing 5, 10, 15, 20, and 25 µg/ml were noted at 324 nm against reagent blanks to obtain calibration curve. Proposed method is novel, economic, eco-friendly, rapid, free from toxicity of organic solvent, accurate and reproducible. Recovery studies and statistical data proved the accuracy, reproducibility and precision of the proposed method. The presence of tablet excipients and phenol did not interfere in the spectrophotometric estimation at 324 nm
Phenotypic lag in macroconidia of N. crassa his-3\u3csup\u3e+\u3c/sup\u3e transsformants and its implication in estimation of nuclear ratios
A majority of prototrophic macroconidia of two of the three histidine transformants of Neurospora crassa tested required histidine for germination. This condition led to an underestimation of the proportion of his-3+ macroconidia in the samples and wronged the estimation of ratio of his-3+/ his-3 nuclei by direct plating method. To correctly estimate nuclear ratio, a sample of colonies from histidine-supplemented plating medium was transferred to histidine drop-out slants and the proportion of auxotrophic and prototrophic colonies was determined from their growth response. The amino acid requirement by prototrophic macroconidia was not specific, was limited to colony formation and was not due to low endogenous content of amino acids
Long-lasting UV protection and mosquito repellent finish on bamboo/tencel blended fabric with microencapsulated essential oil
In this study , bamboo/tencel 50:50 blended fabric has been used for microencapsulation finishing by essential oil combination using exhaustion method in order to enhance the wash durability of the fabric. The three shell materials, namely sodium alginate, Acacia arabica and Moringa oleifera gum and three core materials like thyme oil, cypress oil and grapefruit oils in combination of 2:1:1 have been used. Then the fabrics are tested for functional properties like UV protection and mosquito repellency, and also the fabric is analyzed for allergic test. The result shows that the Moringa oleifera shell finished fabric has very good activity in both the functional property and there is no allergic reaction found. The durability can also be achieved up to 30 washes by using Moringa oliefera gum material as compared to other two
A simple method of obtaining pure microconidia in Neurospora crassa
In order to examine the nuclear types that may be carried in strains of Neurospora collected from nature, we desired a method of selectively inducing microconidiation in mycelia whereby uninucleate microconidia could be obtained for isolating homokaryotic derivatives. We have devised a simple and highly effective method of obtaining pure microconidia from wild-collected strains as well as from N. crassa 74-OR23-1VA
Design and analysis of three phase inverter based Solar PV powered single switch Buck-Boost converter with reduced THD for industrial applications
The development of economical and sustainable eco-friendly renewable source powered power electronic converters have become more attractive in various areas such as automotive, household and industrial applications etc., Bucking and boosting of voltage according to the requirement is also much needed. So, this work proposes a solar PV powered single switch buck-boost converter which reduces implementation cost, minimal voltage and current stress across the capacitors and diodes and less switching power losses. The work structure comprises of solar PV source with modified P and O algorithm based MPPT, single switch buck-boost dc-dc converter, battery backup to store excess energy, three phase inverter with sinusoidal PWM to find optimal switching angles for harmonic control and 3Φ induction motor load. Here reduction of THD is applied to the line to line voltage of the inverter. Performance analysis of the proposed circuit is done using MATLAB/SIMULINK platform. A detailed steady state analysis of the dc-dc converter topology is also analyzed to system stability. The proposed single switch buck-boost converter is designed to provide an output voltage and current of 363V, 45.5A DC from 520V, 35A PV array. The designed converter is then employed to run a three phase full bridge inverter with 440V, 15A AC. From the simulation results, it is found that the solar powered single switch buck-boost with MPPT is stable, efficient with minimal losses and less THD with better quality output
Use of microconidia for testing the genetic purity of Neurospora stocks
Uninucleate microconidia have been used to check the purity of laboratory stocks of Neurospora. Stock cultures of N. crassa and N. intermedia become heterokaryotic due to spontaneous mutation
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