818 research outputs found
Neutrino masses, cosmological bound and four zero Yukawa textures
Four zero neutrino Yukawa textures in a specified weak basis, combined with
symmetry and type-I seesaw, yield a highly constrained and predictive
scheme. Two alternately viable light neutrino Majorana mass matrices
result with inverted/normal mass ordering. Neutrino
masses, Majorana in character and predicted within definite ranges with
laboratory and cosmological inputs, will have their sum probed cosmologically.
The rate for decay, though generally below the reach of
planned experiments, could approach it in some parameter region. Departure from
symmetry due to RG evolution from a high scale and consequent CP
violation, with a Jarlskog invariant whose magnitude could almost reach
, are explored.Comment: Published versio
Morphologic and Taxonomic Analysis of the Weedy and Cultivated Amaranthus hybridus Species Complex
The hybridus species complex of the genus Amaranthus is a group of weedy and cultivated plants from the New World that are considered difficult to identify. Classification schemes have varied between a single species approach, Amaranthus hybridus s.l., and a five species approach that recognizes the widespread weedy A. hybridus s.s., the South American endemic A. quitensis, and the three cultivated taxa (A. hypochondriacus, A. cruentus, and A. caudatus) as distinct species. The goals of this study were to analyze patterns of floral variation within the species complex and to determine distinguishing morphological features of the species. Twenty-one pistillate and twelve staminate floral characters from 41 specimens representing all five species were analyzed morphologically. Results indicate that morphological characters split the hybridus complex into two larger groups; that the widespread weedy A. hybridus divides into two morphologically distinct groups, each associated with different cultivated taxa; and that staminate morphological variation may be more taxonomically informative than previously assumed
Analysis of a model with a common source of CP violation
We work in a model where all CP violating phenomena have a common source. CP
is spontaneously broken at a large scale through the phase of a complex
singlet scalar. An additional singlet vector-like down-type quark
relates this high scale CP violation to low energy. We quantitatively analyze
this model in the quark sector. We obtain the numerical values of the
parameters of the Lagrangian in the quark sector for a specific ansatz of the
down-type quark mass matrix where the weak phase is generated
minimally. vertex will modify in presence of the extra vector-like
down-type quark. From the experimental lower bound of the partial decay width
we find out the lower bound of the additional down-type quark
mass. Tree level flavor changing neutral current appears in this model due to
the presence of the extra vector-like down-type quark. We give the range of
values of the mass splitting in system
using SM box, mediating tree level and mediating one loop diagrams
together for both . We find out the analytical expression for
in this model from standard box, and Higgs mediated penguin
diagrams for system, . From this we numerically
evaluate the decay width difference . We
also find out the numerical values of the CP asymmetry parameters and
for the decays and
respectively. We get the lower bound of the scale through the upper bound
of the strong CP phase.Comment: 20 pages, no figures New materials and references have been added.
Text has been modified. To be appear in J.Phys.
A Regional Scale Modeling Analysis of Aerosol and Trace Gas Distributions over the Eastern Pacific During the INTEX-B Field Campaign
The Sulfur Transport and dEposition Model (STEM) is applied to the analysis of observations obtained during the Intercontinental Chemical Transport Experiment-Phase B (INTEX-B), conducted over the eastern Pacific Ocean during spring 2006. Predicted trace gas and aerosol distributions over the Pacific are presented and discussed in terms of transport and source region contributions. Trace species distributions show a strong west (high) to east (low) gradient, with the bulk of the pollutant transport over the central Pacific occurring between ~20° N and 50° N in the 2–6 km altitude range. These distributions are evaluated in the eastern Pacific by comparison with the NASA DC-8 and NSF/NCAR C-130 airborne measurements along with observations from the Mt. Bachelor (MBO) surface site. Thirty different meteorological, trace gas and aerosol parameters are compared. In general the meteorological fields are better predicted than gas phase species, which in turn are better predicted than aerosol quantities. PAN is found to be significantly overpredicted over the eastern Pacific, which is attributed to uncertainties in the chemical reaction mechanisms used in current atmospheric chemistry models in general and to the specifically high PAN production in the SAPRC-99 mechanism used in the regional model. A systematic underprediction of the elevated sulfate layer in the eastern Pacific observed by the C-130 is another issue that is identified and discussed. Results from source region tagged CO simulations are used to estimate how the different source regions around the Pacific contribute to the trace gas species distributions. During this period the largest contributions were from China and from fires in South/Southeast and North Asia. For the C-130 flights, which operated off the coast of the Northwest US, the regional CO contributions range as follows: China (35%), South/Southeast Asia fires (35%), North America anthropogenic (20%), and North Asia fires (10%). The transport of pollution into the western US is studied at MBO and a variety of events with elevated Asian dust, and periods with contributions from China and fires from both Asia and North America are discussed. The role of heterogeneous chemistry on the composition over the eastern Pacific is also studied. The impacts of heterogeneous reactions at specific times can be significant, increasing sulfate and nitrate aerosol production and reducing gas phase nitric acid levels appreciably (~50%)
Water poverty in the northeastern hill region (India): potential alleviation through multiple-use water systems: cross-learnings from Nepal Hills
Water poverty index / Construction / Multiple use / Water storage / Farming systems / Villages / Social aspects / Drip irrigation / India / Nepal / Nagaland / Mon district / Lampong Sheanghah
Mathematical Model: Comparative Study of Thermal Effects of Laser in Corneal Refractive Surgeries
Lasers have been widely used in ophthalmology. Refractive errors are some of the most common ophthalmic abnormalities worldwide. Laser refractive surgery was developed to correct refractive errors myopia, hyperopia and astigmatism. Two types of laser surgical techniques: lamellar and thermal are available to reshape the corneal curvature. Ultraviolet (UV) emitting argon fluoride (ArF) excimer laser is used to sculpt cornea in lamellar procedures, whereas, infrared (IR) emitting holmium yttrium aluminum garnet (Ho: YAG) laser is used to shrink cornea in thermal procedure. Tissue heating is common in all types of laser surgical techniques. Hence, in this paper, a finite element model is developed to investigate the temperature distribution of cornea in different laser refractive surgeries. Characteristics of optical and thermal processes and influence of the parameters of radiation and tissues on the results of laser action are investigated. The results of mathematical modeling in different surgical techniques are discussed, compared, and validated with experimental results
Soft breaking of symmetry: Light neutrino spectrum and Leptogenesis
Continuous symmetry can generate quasi degenerate mass
spectrum for both left handed light and right handed heavy Majorana neutrinos
assuming that the symmetry preserving non zero parameters are nearly same.
There is an accidental exchange symmetry in the light and heavy
neutrino Majorana mass terms. This implies and
. In addition it generates another zero mixing angle
and one zero mass difference. We restrict ourselves to type-I See-Saw mechanism
for generation of light neutrino mass. We have found that under
symmetry cosmological lepton asymmetry vanishes. We break
such a way that the exchange symmetry preserves
in the neutrino sector. We have seen that light neutrino phenomenology can be
explained under soft breaking of this symmetry. We have observed that softness
of this symmetry breaking depends on the degeneracy of the light neutrino mass
spectrum. Quasi-degeneracy of right handed neutrino mass spectrum opens an
option for resonant leptogenesis. The degeneracy of the right handed neutrino
mass spectrum is restricted through light neutrino data. We observed that for
generation of right sized baryon asymmetry common neutrino mass scale
have to be of the order of and corresponding
right handed neutrino mass scale have to be nearly GeV. We also have
discussed the effect of RG evolution on light neutrino spectrum and also on
baryon asymmetry.Comment: 21 pages, no figure, Revised with the comments on RG effec
A simulation study of pearlite-to-austenite transformation kinetics in rapidly heated hot-rolled low carbon steel
The main aim of the present research was to obtain an optimized microstructure with adequate mechanical properties in a low carbon steel. The effect of microstructure on kinetics of austenite transformation was simulated. A 3.2 mm hot rolled steel was subjected to continuous annealing to obtain properties of Dual Phase 590 grade. Kinetics of austenite transformation was studied with respect to the condition of just pearlite dissolution to form austenite under rapid heating. Annealing parameters were based on process conditions of dual phase steel production in a continuous annealing line. DICTRA was used to simulate heating rates of the order 10–500 °C/s with peak temperatures in the range 750–850 °C to predict isothermal annealing time required for complete dissolution of pearlite into austenite under different temperature-heating rate conditions. Simulation results showed dependency of temperature and heating rate on austenite transformation time. Interestingly, no significant effect of heating rate on complete pearlite dissolution into austenite was evident. Results were validated with limited experimentation on Gleeble. Microstructure analysis validated the simulation results to be accurate. The observations have pertinent inputs while designing industrial continuous annealing line parameters where rapid heating rates are generally encountered (10–20 °C/s).A simulation study of pearlite-to-austenite transformation kinetics in rapidly heated hot-rolled low carbon steel (PDF Download Available). Availablefrom:https://www.researchgate.net/publication/303915593_A_simulation_study_of_pearlite-to austenite_transformation_kinetics_in_rapidly_heated_hot-rolled_low_carbon_steel [accessed Aug 14, 2017]
Baryon asymmetry from leptogenesis with four zero neutrino Yukawa textures
The generation of the right amount of baryon asymmetry of the Universe
from supersymmetric leptogenesis is studied within the type-I seesaw framework
with three heavy singlet Majorana neutrinos and their
superpartners. We assume the occurrence of four zeroes in the neutrino Yukawa
coupling matrix , taken to be symmetric, in the weak basis
where (with real masses ) and the charged leptons are mass diagonal. The quadrant of the single nontrivial
phase, allowed in the corresponding light neutrino mass matrix , gets
fixed and additional constraints ensue from the requirement of matching
with its observed value. Special attention is paid to flavor effects in the
washout of the lepton asymmetry. We also comment on the role of small
departures from high scale symmetry due to RG evolution.Comment: 35 pages, no figure, Published Versio
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