Positive and negative magnetocapacitance in magnetic nanoparticle systems

The dielectric properties of MnFe$_2$O$_4$ and $\gamma$-Fe$_2$O$_3$ magnetic nanoparticles embedded in insulating matrices were investigated. The samples showed frequency dependent dielectric anomalies coincident with the magnetic blocking temperature and significant magnetocapacitance above this blocking temperature, as large as 0.4% at H = 10kOe. For both samples the magnetic field induced change in dielectric constant was proportional to the square of the sample magnetization. These measurements suggest that the dielectric properties of magnetic nanoparticles are closely related to the disposition of magnetic moments in the system. As neither bulk gamma-Fe2O3 nor MnFe2O3 are magnetoelectric materials, this magnetodielectric coupling is believed to arise from extrinsic effects which are discussed in light of recent work relating magnetoresistive and magnetocapacitive behavior.Comment: 3 pages, 3 figure

Neutrino masses, cosmological bound and four zero Yukawa textures

Four zero neutrino Yukawa textures in a specified weak basis, combined with $\mu\tau$ symmetry and type-I seesaw, yield a highly constrained and predictive scheme. Two alternately viable $3\times3$ light neutrino Majorana mass matrices $m_{\nu A}/m_{\nu B}$ 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 $0\nu\beta\beta$ decay, though generally below the reach of planned experiments, could approach it in some parameter region. Departure from $\mu\tau$ symmetry due to RG evolution from a high scale and consequent CP violation, with a Jarlskog invariant whose magnitude could almost reach $6\times 10^{-3}$, are explored.Comment: Published versio

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 $V$ through the phase of a complex singlet scalar. An additional $SU(2)_L$ 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 $4\times4$ down-type quark mass matrix where the weak phase is generated minimally. $Z \bar b b$ vertex will modify in presence of the extra vector-like down-type quark. From the experimental lower bound of the partial decay width $Z\to \bar b b$ 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 $\Delta m_{B_q}$ in $B^0_q-{\bar B}^0_q$ system using SM box, $Z$ mediating tree level and $Z$ mediating one loop diagrams together for both $q=d, s$. We find out the analytical expression for $\Gamma_{12}^q$ in this model from standard box, $Z$ and Higgs mediated penguin diagrams for $B^0_q-{\bar B}^0_q$ system, $q=d,s$. From this we numerically evaluate the decay width difference $|\Delta\Gamma_{B_q}/\Gamma_{B_q}|$. We also find out the numerical values of the CP asymmetry parameters $a_J$ and $a_\pi$ for the decays $B^0_d\to J/\psi K_s$ and $B^0_d\to \pi^+ \pi^-$ respectively. We get the lower bound of the scale $V$ 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.

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

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

Soft breaking of Lμ−LτL_\mu-L_\tau symmetry: Light neutrino spectrum and Leptogenesis

Continuous $U(1)_{L_\mu-L_\tau}$ 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 $\mu\tau$ exchange symmetry in the light and heavy neutrino Majorana mass terms. This implies $\theta_{13}=0$ and $\theta_{23}=\frac{\pi}{4}$. 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 $U(1)_{L_\mu-L_\tau}$ symmetry cosmological lepton asymmetry vanishes. We break $U(1)_{L_\mu-L_\tau}$ such a way that the $\mu\tau$ 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 $m_0$ have to be of the order of $\sqrt{\Delta m^2_{\rm atm}}$ and corresponding right handed neutrino mass scale have to be nearly $10^{13}$ 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

Baryon asymmetry from leptogenesis with four zero neutrino Yukawa textures

The generation of the right amount of baryon asymmetry $\eta$ of the Universe from supersymmetric leptogenesis is studied within the type-I seesaw framework with three heavy singlet Majorana neutrinos $N_i\,\,(i = 1,2,3)$ and their superpartners. We assume the occurrence of four zeroes in the neutrino Yukawa coupling matrix $Y_\nu$, taken to be $\mu\tau$ symmetric, in the weak basis where $N_i$ (with real masses $M_i>0$) and the charged leptons $l_\alpha\,\, (\alpha = e,\mu,\tau)$ are mass diagonal. The quadrant of the single nontrivial phase, allowed in the corresponding light neutrino mass matrix $m_\nu$, gets fixed and additional constraints ensue from the requirement of matching $\eta$ 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 $\mu\tau$ symmetry due to RG evolution.Comment: 35 pages, no figure, Published Versio

Multi-scale modeling study of the source contributions to near-surface ozone and sulfur oxides levels over California during the ARCTAS-CARB period

Chronic high surface ozone (O_3) levels and the increasing sulfur oxides (SO_x = SO_2 + SO_4) ambient concentrations over South Coast (SC) and other areas of California (CA) are affected by both local emissions and long-range transport. In this paper, multi-scale tracer, full-chemistry and adjoint simulations using the STEM atmospheric chemistry model are conducted to assess the contribution of local emission sourcesto SC O_3 and to evaluate the impacts of transported sulfur and local emissions on the SC sulfur budgetduring the ARCTAS-CARB experiment period in 2008. Sensitivity simulations quantify contributions of biogenic and fire emissions to SC O_3 levels. California biogenic and fire emissions contribute 3–4 ppb to near-surface O_3 over SC, with larger contributions to other regions in CA. During a long-range transport event from Asia starting from 22 June, high SO_x levels (up to ~0.7 ppb of SO_2 and ~1.3 ppb of SO_4) is observed above ~6 km, but they did not affect CA surface air quality. The elevated SO_x observed at 1–4 km is estimated to enhance surface SO_x over SC by ~0.25 ppb (upper limit) on ~24 June. The near-surface SO_x levels over SC during the flight week are attributed mostly to local emissions. Two anthropogenic SO_x emission inventories (EIs) from the California Air Resources Board (CARB) and the US Environmental Protection Agency (EPA) are compared and applied in 60 km and 12 km chemical transport simulations, and the results are compared withobservations. The CARB EI shows improvements over the National Emission Inventory (NEI) by EPA, but generally underestimates surface SC SO_x by about a factor of two. Adjoint sensitivity analysis indicated that SO_2 levels at 00:00 UTC (17:00 local time) at six SC surface sites were influenced by previous day maritime emissions over the ocean, the terrestrial emissions over nearby urban areas, and by transported SO_2 from the north through both terrestrial and maritime areas. Overall maritime emissions contribute 10–70% of SO2 and 20–60% fine SO_4 on-shore and over the most terrestrial areas, with contributions decreasing with in-land distance from the coast. Maritime emissions also modify the photochemical environment, shifting O_3 production over coastal SC to more VOC-limited conditions. These suggest an important role for shipping emission controls in reducing fine particle and O_3 concentrations in SC

Multi-scale modeling study of the source contributions to near-surface ozone and sulfur oxides levels over California during the ARCTAS-CARB period

Chronic high surface ozone (O3) levels and the increasing sulfur oxides (SOx = SO2+SO4) ambient concentrations over South Coast (SC) and other areas of California (CA) are affected by both local emissions and long-range transport. In this paper, multi-scale tracer, full-chemistry and adjoint simulations using the STEM atmospheric chemistry model are conducted to assess the contribution of local emission sourcesto SC O3 and to evaluate the impacts of transported sulfur and local emissions on the SC sulfur budgetduring the ARCTAS-CARB experiment period in 2008. Sensitivity simulations quantify contributions of biogenic and fire emissions to SC O3 levels. California biogenic and fire emissions contribute 3–4 ppb to near-surface O3 over SC, with larger contributions to other regions in CA. During a long-range transport event from Asia starting from 22 June, high SOx levels (up to ~0.7 ppb of SO2 and ~1.3 ppb of SO4) is observed above ~6 km, but they did not affect CA surface air quality. The elevated SOx observed at 1–4 km is estimated to enhance surface SOx over SC by ~0.25 ppb (upper limit) on ~24 June. The near-surface SOx levels over SC during the flight week are attributed mostly to local emissions. Two anthropogenic SOx emission inventories (EIs) from the California Air Resources Board (CARB) and the US Environmental Protection Agency (EPA) are compared and applied in 60 km and 12 km chemical transport simulations, and the results are compared withobservations. The CARB EI shows improvements over the National Emission Inventory (NEI) by EPA, but generally underestimates surface SC SOx by about a factor of two. Adjoint sensitivity analysis indicated that SO2 levels at 00:00 UTC (17:00 local time) at six SC surface sites were influenced by previous day maritime emissions over the ocean, the terrestrial emissions over nearby urban areas, and by transported SO2 from the north through both terrestrial and maritime areas. Overall maritime emissions contribute 10–70% of SO2 and 20–60% fine SO4 on-shore and over the most terrestrial areas, with contributions decreasing with in-land distance from the coast. Maritime emissions also modify the photochemical environment, shifting O3 production over coastal SC to more VOC-limited conditions. These suggest an important role for shipping emission controls in reducing fine particle and O3concentrations in SC

Towards Minimal S4 Lepton Flavor Model

We study lepton flavor models with the $S_4$ flavor symmetry. We construct simple models with smaller numbers of flavon fields and free parameters, such that we have predictions among lepton masses and mixing angles. The model with a $S_4$ triplet flavon is not realistic, but we can construct realistic models with two triplet flavons, or one triplet and one doublet flavons.Comment: 18 pages, 4 figures, references are adde