16,037 research outputs found
Air pollutant production by algal cell cultures
The production of phytotoxic air pollutants by cultures of Chlorella vulgaris and Euglena gracilis is considered. Algal and plant culture systems, a fumigation system, and ethylene, ethane, cyanide, and nitrogen oxides assays are discussed. Bean, tobacco, mustard green, cantaloupe and wheat plants all showed injury when fumigated with algal gases for 4 hours. Only coleus plants showed any resistance to the gases. It is found that a closed or recycled air effluent system does not produce plant injury from algal air pollutants
Two-Hop Interference Channels: Impact of Linear Time-Varying Schemes
We consider the two-hop interference channel (IC) with constant real channel
coefficients, which consists of two source-destination pairs, separated by two
relays. We analyze the achievable degrees of freedom (DoF) of such network when
relays are restricted to perform scalar amplify-forward (AF) operations, with
possibly time-varying coefficients. We show that, somewhat surprisingly, by
providing the flexibility of choosing time-varying AF coefficients at the
relays, it is possible to achieve 4/3 sum-DoF. We also develop a novel outer
bound that matches our achievability, hence characterizing the sum-DoF of
two-hop interference channels with time-varying AF relaying strategies.Comment: To appear in Proc. of ISIT 2013 (proof of lemma added
Spin susceptibility and the pi-excitation in underdoped cuprates
The dynamical spin susceptibility chi'' at wave vector (pi, pi) and the
spectrum pi'' of the spin-triplet particle--particle excitation with center of
mass momentum (pi, pi) (pi-excitation) are considered in the slave-boson
formulation of the t--J-model. Propagators are calculated in a diagrammatic
t-matrix approximation in the d-wave superconducting state for a wide doping
range. The resulting spectra chi'' and pi'' both show a resonance at a doping
dependent energy, in qualitative agreement with recent numerical cluster
calculations. In underdoped systems, the peak position is comparable to that
found in neutron scattering experiments. The peak in chi'' as well as pi'' is
at low doping entirely caused by spin fluctuations, whereas the triplet
particle--particle channel does not contribute as a collective mode.Comment: 3 pages, 4 eps-figures included, uses revtex, eps
Leptogenesis from Soft Supersymmetry Breaking (Soft Leptogenesis)
Soft leptogenesis is a scenario in which the cosmic baryon asymmetry is
produced from a lepton asymmetry generated in the decays of heavy sneutrinos
(the partners of the singlet neutrinos of the seesaw) and where the relevant
sources of CP violation are the complex phases of soft supersymmetry-breaking
terms. We explain the motivations for soft leptogenesis, and review its basic
ingredients: the different CP-violating contributions, the crucial role played
by thermal corrections, and the enhancement of the efficiency from lepton
flavour effects. We also discuss the high temperature regime GeV in
which the cosmic baryon asymmetry originates from an initial asymmetry of an
anomalous -charge, and soft leptogenesis reembodies in -genesis.Comment: References updated. Some minor corrections to match the published
versio
Phase field modelling of surfactants in multi-phase flow
A diffuse interface model for surfactants in multi-phase flow with three or
more fluids is derived. A system of Cahn-Hilliard equations is coupled with a
Navier-Stokes system and an advection-diffusion equation for the surfactant
ensuring thermodynamic consistency. By an asymptotic analysis the model can be
related to a moving boundary problem in the sharp interface limit, which is
derived from first principles. Results from numerical simulations support the
theoretical findings. The main novelties are centred around the conditions in
the triple junctions where three fluids meet. Specifically the case of local
chemical equilibrium with respect to the surfactant is considered, which allows
for interfacial surfactant flow through the triple junctions
Streda-like formula in spin Hall effect
A generalized Streda formula is derived for the spin transport in spin-orbit
coupled systems. As compared with the original Streda formula for charge
transport, there is an extra contribution of the spin Hall conductance whenever
the spin is not conserved. For recently studied systems with quantum spin Hall
effect in which the z-component spin is conserved, this extra contribution
vanishes and the quantized value of spin Hall conductivity can be reproduced in
the present approach. However, as spin is not conserved in general, this extra
contribution can not be neglected, and the quantization is not exact.Comment: 4 pages, no figur
Environmental Pollution and Chronic Disease Management – A Prognostics Approach
No abstract available
Matrix elements of four-quark operators and \Delta L=2 hyperon decays
The study of neutrinoless double beta decays of nuclei and hyperons require
the calculation of hadronic matrix elements of local four-quark operators that
change the total charge by two units \Delta Q=2 . Using a low energy effective
Lagrangian that induces these transitions, we compute these hadronic matrix
elements in the framework of the MIT bag model. As an illustrative example we
evaluate the amplitude and transition rate of \Sigma- -> p e- e-, a decay
process that violates lepton number by two units (\Delta L=2). The relevant
matrix element is evaluated without assuming the usual factorization
approximation of the four-quark operators and the results obtained in both
approaches are compared.Comment: 13 pages, 2 .eps figure
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