Optimization of quantum cascade laser operation by geometric design of cascade active band in open and closed models

Using the effective mass and rectangular potential approximations, the theory of electron dynamic conductivity is developed for the plane multilayer resonance tunnel structure placed into a constant electric field within the model of open nanosystem, and oscillator forces of quantum transitions within the model of closed nanosystem. For the experimentally produced quantum cascade laser with four-barrier active band of separate cascade, it is proven that just the theory of dynamic conductivity in the model of open cascade most adequately describes the radiation of high frequency electromagnetic field while the electrons transport through the resonance tunnel structure driven by a constant electric field.Comment: 10 pages, 2 figure

Nematicidal activity of aqueous tinctures of medicinal plants against larvae of the nematodes Strongyloides papillosus and Haemonchus contortus

The study focuses on in vitro effect of aqueous tinctures of 48 species of herbaceous, shrub and tree plants on the first-third stage larvae of Strongyloides papillosus (Wedl, 1856) and third-stage larvae of Haemonchus contortus (Rudolphi, 1803) Cobb, 1898. The highest level of the effect was exerted by 3% aqueous tinctures of Wisteria sinensis (Sims) DC., Ailanthus altissima (Mill.) Swingle, Laburnum anagyroides Medik., Quercus petraea subsp. iberica (Steven ex M. Bieb.) Krassiln., Ginkgo biloba L., Colchicum autumnale L., Aristolochia manshuriensis Kom., Celastrus scandens L., Securigera varia (L.) Lassen, Magnolia kobus DC. Over 90% of the first and second non-invasive stage larvae of S. papillosus died at contact with these tinctures. The lowest parameters of LD50 were seen for L. anagyroides, Juniperus sabina L., C. scandens, M. kobus, A. manshuriensis, Wisteria sinensis (Sims) DC. and Securigera varia (L.) Lassen. Invasive larvae of S. papillosus and H. contortus were resistant to the effect of all the 48 surveyed species of plants. Third-stage larvae of H. contortus remained vital when exposed for 24 h to all the studied concentrations up to 3% aqueous tincture of plants. The results of the experiments and also the analysis of the literature indicate the necessity to continue the survey on nematocidial activity of aqueous tinctures and alcveshol extracts of plants

SU(2) Gluodynamics and HP1 sigma-model embedding: Scaling, Topology and Confinement

We investigate recently proposed HP1 sigma-model embedding method aimed to study the topology of SU(2) gauge fields. The HP1 based topological charge is shown to be fairly compatible with various known definitions. We study the corresponding topological susceptibility and estimate its value in the continuum limit. The geometrical clarity of HP1 approach allows to investigate non-perturbative aspects of SU(2) gauge theory on qualitatively new level. In particular, we obtain numerically precise estimation of gluon condensate and its leading quadratic correction. Furthermore, we present clear evidences that the string tension is to be associated with global (percolating) regions of sign-coherent topological charge. As a byproduct of our analysis we estimate the continuum value of quenched chiral condensate and the dimensionality of regions, which localize the lowest eigenmodes of overlap Dirac operator.Comment: 22 pages, 18 ps figures, revtex4. Replaced to match published version (PRD, to appear