3,215 research outputs found
On Probing theta_{23} in Neutrino Telescopes
Among all neutrino mixing parameters, the atmospheric neutrino mixing angle
theta_{23} introduces the strongest variation on the flux ratios of ultra high
energy neutrinos. We investigate the potential of these flux ratio measurements
at neutrino telescopes to constrain theta_{23}. We consider astrophysical
neutrinos originating from pion, muon-damped and neutron sources and make a
comparative study of their sensitivity reach to theta_{23}. It is found that
neutron sources are most favorable for testing deviations from maximal
theta_{23}. Using a chi^2 analysis, we show in particular the power of
combining (i) different flux ratios from the same type of source, and also (ii)
combining flux ratios from different astrophysical sources. We include in our
analysis ``impure'' sources, i.e., deviations from the usually assumed initial
(1 : 2 : 0), (0 : 1 : 0) or (1 : 0 : 0) flux compositions.Comment: 17 pages, 5 figures. Added discussion on experimental errors. To
appear in PR
Transesterification of Waste Cooking Oil Catalysed by Crystalline Copper Doped Zinc Oxide Nanocatalyst
Biodiesel has its unique position in the field of renewable energy as alternate fuel to diesel due to fuel price, energy requirement and petroleum crisis. In this study, biodiesel was produced from Waste Cooking Oil (WCO) using Copper doped Zinc Oxide (CZO) nanocatalysts. The synthesized Copper doped Zinc Oxide nanocatalysts were characterized by X-Ray Diffraction (XRD) and High Resolution Transmission Electron Microscope (HRTEM). Design of experiment was framed using Taguchi method to limit the experiments and to find the optimum reaction conditions. The effect of process parameters such as oil-to-methanol ratio (O/M), catalyst type, catalyst concentration, temperature and time on the transesterification reactions using characterized Copper doped Zinc Oxide nanocatalyst were investigated. The 4% (weight /weight) nanocatalyst concentration, 1:5 Oil to methanol molar ratio at 60°C temperature and 40 minutes of reaction time were found to be optimum, in which the maximum biodiesel yield of 98 % (w/w) was obtained. Hence it was determined that nanocatalysts exhibited good catalytic activities on biodiesel production from Waste Cooking Oil (WCO)
Probing the deviation from maximal mixing of atmospheric neutrinos
Pioneering atmospheric muon neutrino experiments have demonstrated the
near-maximal magnitude of the flavor mixing angle . But the
precise value of the deviation from
maximality (if nonzero) needs to be known, being of great interest --
especially to builders of neutrino mass and mixing models. We quantitatively
investigate in a three generation framework the feasibility of determining
in a statistically significant manner from studies of the atmospheric
survival probability including both vacuum oscillations
and matter effects. We show how this determination will be sharpened by
considering the up-down ratios of observed - and -induced
events and the differences of these ratios in specified energy and zenith angle
bins. We consider 1 Megaton year of exposure to a magnetized iron calorimeter
such as the proposed INO detector ICAL, taking into account both energy and
zenith angle resolution functions. The sensitivity of such an exposure and the
dependence of the determination of on the concerned oscillation parameters
are discussed in detail. The vital use of matter effects in fixing the octant
of is highlighted.Comment: Version to appear in PR
Isolation, screening, and characterization of plant growth enhancing endophytic bacteria from halophytic Heliotropium curassavicum L. collected from salt stress areas of Srikakulam, Andhra Pradesh
Farmers use excessive chemical fertilizers to boost crop productivity to meet growing agricultural demands. However, this practice is costly and environmentally hazardous. Sustainable increase in crop yield can be achieved through alternatives like microbial-based fertilizers. In the quest to identify plant growth-promoting endophytic bacteria, the present study was carried out and selected unexplored halophytic plant Heliotropium curassavicum L. Thirteen endophytic bacterial strains were isolated from both aerial and root portions of H.curassavicum. These isolates were tested for salt tolerance, enzyme production, and synthesis of growth-promoting secondary metabolites, like Indole-3-acetic acid (IAA) and phosphate solubilization . Most of the isolates belonged to the Bacillus family, exhibiting varying Gram staining and biochemical reactions. The majority are Gram-positive bacteria, non-motile, spore formers, and exist in two cells or chains. All isolates could tolerate up to 10% NaCl concentration and a temperature of 42°C. Based on phenotypic, bio-chemical characteristics, isolate HCR3 showed promising properties in synthesizing IAA and phosphate solubilization abilities. The isolate HCR3 grew well upto 10% NaCl concentration and also 42°C temperature. Based on molecular characterization by using 16S rRNA gene-based analysis HCR3 isolate was identified and belonged to the Genus Pseudomonas with the highest similarity index with Pseudomonas khazarica sp. HCR3 showed IAA production of 37µg ml-1, had a phosphate solubilization ability of 3.5 ppm, and recorded protease activity on gelatin medium. The findings highlight the potential of HCR3 and other strains from halophytic H. curassavicum L. to enhance plant growth through secondary bioactive metabolites, offering eco-friendly solutions for sustainable agriculture
Screening of salt tolerant endophytic bacteria with plant growth promoting characters isolated from Acanthus ilicifolius L., a species of mangrove ecosystem located at Corangi wildlife sanctuary, Andhra Pradesh
Mangroves harbour many beneficial microorganisms in their rhizosphere, phyllosphere and endophytically, which forms an ideal ecological habitation for isolating halotolerant endophytic bacteria with unique characteristics. Endophytes can produce numerous bioactive secondary metabolites and phytohormones, which may be directly or in some way beneficial to the host plant. The present study aimed to identify novel endophytes capable of producing plant growth-promoting substances. The mangrove plants Acanthus ilicifolius L. at Corangi Wildlife Sanctuary were selected, and their leaves and roots were collected for endophyte isolation. Eight isolates from the leaves and roots were collected, purified and preserved. All these isolates were subjected to morphological, phenotypical and biochemical studies. Isolates were grown best at 3% NaCl nutrient agar and could tolerate salinity upto 8%NaCl. Most of them could grow upto 42°C. The majority were gram’s positive, motile, aerobic, rod-shaped and some were gram’s negative, rod-shaped organisms. Many of the endophytic organisms had the ability to synthesize Indole-3-acetic acid(IAA) varied from 0.7 µg/ml (AIL1) to 51.0 µg/ml (AIL2) and the highest phosphate solubilizing ability was recorded with AIR3 (3.71 ppm) followed by AIR4 (3.00 ppm) and lowest was recorded by AIL4 (1.80 ppm). Among total isolates, AIL2 (51µg/ml) showed promising potential in producing IAA and had phosphate solubilization ability. Based on 16S ribosomal RNA molecular method the isolate AIL2 was identified as Bacillus altitudinis. This is the first to report that B.altitudinis strain AIL2 isolated from A.ilicifolius L. could produce IAA, which can be used as a bioinoculant in agriculture and allied sector
Confusing Sterile Neutrinos with Deviation from Tribimaximal Mixing at Neutrino Telescopes
We expound the impact of extra sterile species on the ultra high energy
neutrino fluxes in neutrino telescopes. We use three types of well-known flux
ratios and compare the values of these flux ratios in presence of sterile
neutrinos, with those predicted by deviation from the tribimaximal mixing
scheme. We show that in the upcoming neutrino telescopes, its easy to confuse
between the signature of sterile neutrinos with that of the deviation from
tribimaximal mixing. We also show that if the measured flux ratios acquire a
value well outside the range predicted by the standard scenario with three
active neutrinos only, it might be possible to tell the presence of extra
sterile neutrinos by observing ultra high energy neutrinos in future neutrino
telescopes.Comment: 22 pages, version to appear in Phys. Rev.
Transesterification of Waste Cooking Oil Catalysed by Crystalline Copper Doped Zinc Oxide Nanocatalyst
Biodiesel has its unique position in the field of renewable energy as alternate fuel to diesel due to fuel price, energy requirement and petroleum crisis. In this study, biodiesel was produced from Waste Cooking Oil (WCO) using Copper doped Zinc Oxide (CZO) nanocatalysts. The synthesized Copper doped Zinc Oxide nanocatalysts were characterized by X-Ray Diffraction (XRD) and High Resolution Transmission Electron Microscope (HRTEM). Design of experiment was framed using Taguchi method to limit the experiments and to find the optimum reaction conditions. The effect of process parameters such as oil-to-methanol ratio (O/M), catalyst type, catalyst concentration, temperature and time on the transesterification reactions using characterized Copper doped Zinc Oxide nanocatalyst were investigated. The 4% (weight /weight) nanocatalyst concentration, 1:5 Oil to methanol molar ratio at 60°C temperature and 40 minutes of reaction time were found to be optimum, in which the maximum biodiesel yield of 98 % (w/w) was obtained. Hence it was determined that nanocatalysts exhibited good catalytic activities on biodiesel production from Waste Cooking Oil (WCO)
Neutrinoless Double Beta Decay and Future Neutrino Oscillation Precision Experiments
We discuss to what extent future precision measurements of neutrino mixing
observables will influence the information we can draw from a measurement of
(or an improved limit on) neutrinoless double beta decay. Whereas the Delta m^2
corresponding to solar and atmospheric neutrino oscillations are expected to be
known with good precision, the parameter theta_{12} will govern large part of
the uncertainty. We focus in particular on the possibility of distinguishing
the neutrino mass hierarchies and on setting a limit on the neutrino mass. We
give the largest allowed values of the neutrino masses which allow to
distinguish the normal from the inverted hierarchy. All aspects are discussed
as a function of the uncertainty stemming from the involved nuclear matrix
elements. The implications of a vanishing, or extremely small, effective mass
are also investigated. By giving a large list of possible neutrino mass
matrices and their predictions for the observables, we finally explore how a
measurement of (or an improved limit on) neutrinoless double beta decay can
help to identify the neutrino mass matrix if more precise values of the
relevant parameters are known.Comment: 35 pages, 12 figures. Comments and references added. To appear in PR
Turbulent Supernova Shock Waves and the Sterile Neutrino Signature in Megaton Water Detectors
The signatures of sterile neutrinos in the supernova neutrino signal in
megaton water Cerenkov detectors are studied. Time dependent modulation of the
neutrino signal emerging from the sharp changes in the oscillation probability
due to shock waves is shown to be a smoking gun for the existence of sterile
neutrinos. These modulations and indeed the entire neutrino oscillation signal
is found to be different for the case with just three active neutrinos and the
cases where there are additional sterile species mixed with the active
neutrinos. The effect of turbulence is taken into account and it is found that
the effect of the shock waves, while modifed, remain significant and
measurable. Supernova neutrino signals in water detectors can therefore give
unambiguous proof for the existence of sterile neutrinos, the sensitivity
extending beyond that for terrestial neutrino experiments. In addition the time
dependent modulations in the signal due to shock waves can be used to trace the
evolution of the shock wave inside the supernova.Comment: 28 pages, 11 figure
Optical properties and spatial distribution of MgII absorbers from SDSS image stacking
We present a statistical analysis of the photometric properties and spatial
distribution of more than 2,800 MgII absorbers with 0.37<z<1 and rest
equivalent width W_0(\lambda2796)>0.8\AA detected in SDSS quasar spectra. Using
an improved image stacking technique, we measure the cross-correlation between
MgII gas and light (in the g, r, i and z-bands) from 10 to 200 kpc and infer
the light-weighted impact parameter distribution of MgII absorbers. Such a
quantity is well described by a power-law with an index that strongly depends
on W_0, ranging from ~-1 for W_0~ 1.5\AA. At redshift
0.37<z<0.55, we find the average luminosity enclosed within 100 kpc around MgII
absorbers to be M_g=-20.65+-0.11 mag, which is ~0.5 L_g*. The global
luminosity-weighted colors are typical of present-day intermediate type
galaxies. However, while the light of weaker absorbers originates mostly from
red passive galaxies, stronger systems display the colors of blue star-forming
galaxies. Based on these observations, we argue that the origin of strong MgII
absorber systems might be better explained by models of metal-enriched gas
outflows from star-forming/bursting galaxies. Our analysis does not show any
redshift dependence for both impact parameter and rest-frame colors up to z=1.
However, we do observe a brightening of the absorbers related light at high
redshift (~50% from z~0.4 to 1). We argue that MgII absorbers are a phenomenon
typical of a given evolutionary phase that more massive galaxies experience
earlier than less massive ones, in a downsizing fashion. (abridged)Comment: ApJ in press, 28 pages, 16 figures, using emulateapj. Only typo
corrections wrt the original submission (v1
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