On essential self-adjointness for magnetic Schroedinger and Pauli operators on the unit disc in R^2

We study the question of magnetic confinement of quantum particles on the unit disk \ID in \IR^2, i.e. we wish to achieve confinement solely by means of the growth of the magnetic field $B(\vec x)$ near the boundary of the disk. In the spinless case we show that $B(\vec x)\ge \frac{\sqrt 3}{2}\cdot\frac{1}{(1-r)^2}-\frac{1}{\sqrt 3}\frac{1}{(1-r)^2\ln \frac{1}{1-r}}$, for $|\vec x|$ close to 1, insures the confinement provided we assume that the non-radially symmetric part of the magnetic field is not very singular near the boundary. Both constants $\frac{\sqrt 3}{2}$ and $-\frac{1}{\sqrt 3}$ are optimal. This answers, in this context, an open question from Y. Colin de Verdi\`ere and F. Truc. We also derive growth conditions for radially symmetric magnetic fields which lead to confinement of spin 1/2 particles.Comment: 18 pages; the main theorem has been expanded and generalize

Instability of a Pseudo-Relativistic Model of Matter with Self-Generated Magnetic Field

For a pseudo-relativistic model of matter, based on the no-pair Hamiltonian, we prove that the inclusion of the interaction with the self-generated magnetic field leads to instability for all positive values of the fine structure constant. This is true no matter whether this interaction is accounted for by the Breit potential, by an external magnetic field which is chosen to minimize the energy, or by the quantized radiation field.Comment: 13 pages, AMS-LaTe

CONSIDERATIONS REGARDING FISH FARMING IN POLYCULTURE SYSTEM

Marine aquaculture is becoming more widely recognized as a viable alternative to fishing for supplying high-quality protein to the world's rising population. Capture fisheries output is falling short of global demand, and yearly seafood consumption has increased by more than double in the previous three decades. Under these conditions, raising fish in a polyculture system could be a viable option for increasing production globally, but with low effects on the environment

REVIEW OF THE MAIN EQUIPMENT USED FOR SEPARATING CONTAMINANTS FROM WHEAT SEEDS, CLASSIFICATION ACCORDING TO THEIR FUNCTIONAL ROLE

Wheat seed cleaning require a complex set of operations to be performed in order to remove impurities from the grain mass and obtain high quality final products. These operations are carried out in a technological flow, starting from harvesting until the final processing stage, depending on the crop destination. The stages used to clean the wheat grain are usually following the operations: cleaning in aerodynamic separators, cleaning with sieves, sorting in indent cylinder separator, additional cleaning in special cleaning machines. The paper presents a synthesis of the primary processing phases of wheat seeds for the use in the food industry depending on their functional role

CONSIDERATIONS REGARDING THE DEVELOPMENT OF NEW EQUIPMENT USED FOR HEMP HARVESTING

The important potential of cultivating hemp for fiber and cannabidiol extraction for medicinal use, makes this plant return to the attention of agronomists and medical researchers. Another strength of this plant is the potential of produced fibers to contribute to the decrease in the use of plastic in the near future, helping to reduce dependence on fossil fuels. In addition, hemp could be a more economically attractive alternative for ethanol generation or even for the production of high-strength construction materials. The paper aims to present several technologies used for hemp harvesting

Smooth adiabatic evolutions with leaky power tails

Adiabatic evolutions with a gap condition have, under a range of circumstances, exponentially small tails that describe the leaking out of the spectral subspace. Adiabatic evolutions without a gap condition do not seem to have this feature in general. This is a known fact for eigenvalue crossing. We show that this is also the case for eigenvalues at the threshold of the continuous spectrum by considering the Friedrichs model.Comment: Final form, to appear in J. Phys. A; 11 pages, no figure

THE QUALITY OF THE AQUATIC ENVIRONMENT IN FISH PONDS

In our country, the most widespread growth system is the semi-intensive one with growth units represented by ponds (anthropogenic ecosystems). The semi-intensive fish culture is based on the natural productivity and / or enriched by fertilization of the anthropogenic ecosystems, respectively also on the administration of supplementary food. In fact, semi-intensive cultivation involves obtaining a fish biomass with low production costs due to the use of inexpensive inputs. The productionprofile and the way of obtaining it determine the structure and duration oftheexploitation cycle within a fish farm

ASPECTS REGARDING THE ENERGY POTENTIAL OF THE MISCANTHUS PLANT

Greenhouse gases resulting from human activities are the most significant driver of climate change. The use of renewable resources obtained by cultivating energy plants, that have the potential of replacing fossil fuels, is one of the most important approaches to reduce the consequences produced by this global climate change hazard.The paper presents information regarding the energy potential of the Miscanthus plant, that can be explored in three main directions: to produce bioethanol, biogas or solid biomass (chopped, pellets or briquettes), then use thermochemical processes for energy production

Bloch bundles, Marzari-Vanderbilt functional and maximally localized Wannier functions

We consider a periodic Schroedinger operator and the composite Wannier functions corresponding to a relevant family of its Bloch bands, separated by a gap from the rest of the spectrum. We study the associated localization functional introduced by Marzari and Vanderbilt, and we prove some results about the existence and exponential localization of its minimizers, in dimension d < 4. The proof exploits ideas and methods from the theory of harmonic maps between Riemannian manifolds.Comment: 37 pages, no figures. V2: the appendix has been completely rewritten. V3: final version, to appear in Commun. Math. Physic