Theory of one-dimensional double-barrier quantum pump in two-frequency signal regime

A one-dimensional system with two $\delta$-like barriers or wells bi-chromaticaly oscillating at frequencies $\omega$ and $2\omega$ is considered. The alternating signal leads to the direct current across the structure (even in a symmetric system). The properties of this quantum pump are studied in a wide range of the system parameters.Comment: 4 pages, 5 figure

Population dynamics of reindeer

Five types of reindeer populations are distinguished in terms of population dynamics, population density, social structure and migration distance. Differences in the biological rhythms of the populations result in calving occuring 20 days before snow melting in all populations as well as maximal utilization by the deer of young green vegetation in summer. The growth of antlers may serve as a regulatior of biological rhytms. Populations differ in the level of social motivation. Formation of groups of not less than 30-35 animals ensures cooperative protection from insects and management of the group by man. The fidelity to the calving sites, summer ranges and constant migration routes is based on the common orientation reactions of the animals and social attraction. The direction and migration routes are detemined by obligate learning. The dynamics of populations depends on the fertility of 2 and 3 year old females which is determined by feeding conditions in summer and the activity of males during the rut. Migration plays an important role in the population dynamics

Properties of 1D two-barrier quantum pump with harmonically oscillating barriers

We study a one-dimensional quantum pump composed of two oscillating delta-functional barriers. The linear and non-linear regimes are considered. The harmonic signal applied to any or both barriers causes the stationary current. The direction and value of the current depend on the frequency, distance between barriers, value of stationary and oscillating parts of barrier potential and the phase shift between alternating voltages.Comment: 7 pages, 8 figure

Seed dimorphism nutrients and salinity differentially affect seed traits of the desert halophyte Suaeda aralocaspica via multiple maternal effects.

Background: Maternal effects may influence a range of seed traits simultaneously and are likely to be context-dependent. Disentangling the interactions of plant phenotype and growth environment on various seed traits is important for understanding regeneration and establishment of species in natural environments. Here, we used the seed-dimorphic plant Suaeda aralocaspica to test the hypothesis that seed traits are regulated by multiple maternal effects.Results: Plants grown from brown seeds had a higher brown:black seed ratio than plants from black seeds, and germination percentage of brown seeds was higher than that of black seeds under all conditions tested. However, the coefficient of variation (CV) for size of black seeds was higher than that of brown seeds. Seeds had the smallest CV at low nutrient and high salinity for plants from brown seeds and at low nutrient and low salinity for plants from black seeds. Low levels of nutrients increased size and germinability of black seeds but did not change the seed morph ratio or size and germinability of brown seeds. High levels of salinity decreased seed size but did not change the seed morph ratio. Seeds from high-salinity maternal plants had a higher germination percentage regardless of level of germination salinity.Conclusions: Our study supports the multiple maternal effects hypothesis. Seed dimorphism, nutrient and salinity interacted in determining a range of seed traits of S. aralocaspica via bet-hedging and anticipatory maternal effects. This study highlights the importance of examining different maternal factors and various offspring traits in studies that estimate maternal effects on regeneration. © 2012 Wang et al.; licensee BioMed Central Ltd

The radiation field on product cones

We consider the wave equation on a product cone and find a joint asymptotic expansion for forward solutions near null and future infinities. The rates of decay seen in the expansion are the resonances of a hyperbolic cone on the "northern cap" of the compactification and were computed by the authors in a previous paper. The expansion treats an asymptotic regime not considered in the influential work of Cheeger and Taylor. The main result follows the blueprint laid out in the asymptotically Minkowski setting; the key new element consists of propagation estimates near the conic singularities. The proof of the propagation estimates builds on the work of Melrose--Vasy--Wunsch in the spacetime and on Gannot--Wunsch in the semiclassical regime.Comment: 38 pages, 3 figures. The main result builds on previous work of the first author with Vasy and Wunsch (arXiv:1212.5141 and arXiv:1602.04795), the propagation estimates in the bulk build on the work of Melrose--Vasy--Wunsch (arXiv:math/0612750), and the semiclassical propagation estimates build on work of Gannot--Wunsch (arXiv:1806.01813

Populations of wild and feral reindeer in Siberia and Far East of Russia

Identification and cataloging of discrete reindeer (Rangifer tarandus) populations in Siberia and the Far East of Russia has not been carried out. This prohibits accurate measures of population structure and dynamics that would allow more intensive management of this important renewable resource. To rectify the lack of information, an inventory was made that identifies 84 wild populations and 3 feral populations originating from domestic reindeer. This inventory summarizes the information available on the location, approximate population size, approximate range size, and occurrence by ecoregions and habitat types of each of those 87 reindeer populations. The 87 reindeer populations used a collective landmass of about 3 000 000 km2. The range size for each population was calculated to be between 446 km2 and 392 267 km2, with a mean ± SE of 34 033 ± 5734 km2. The 86 populations for which population size could be approximated totaled 790 655 reindeer, with an approximate mean ± SE of 9194 ± 2517, a minimum size of 50, and maximum size of 145 000. The location of the calving grounds could be determined for only 26 (30%) of the 87 reindeer populations

Conductivity of 2D many-component electron gas, partially-quantized by magnetic field

The 2D semimetal consisting of heavy holes and light electrons is studied. The consideration is based on assumption that electrons are quantized by magnetic field while holes remain classical. We assume also that the interaction between components is weak and the conversion between components is absent. The kinetic equation for holes colliding with quantized electrons is utilized. It has been stated that the inter-component friction and corresponding correction to the dissipative conductivity $\sigma_{xx}$ {\it do not vanish at zero temperature} due to degeneracy of the Landau levels. This correction arises when the Fermi level crosses the Landau level. The limits of kinetic equation applicability were found. We also study the situation of kinetic memory when particles repeatedly return to the points of their meeting.Comment: 13 pages, 1 figur