Optimal control of electromagnetic field using metallic nanoclusters

The dielectric properties of metallic nanoclusters in the presence of an applied electromagnetic field are investigated using non-local linear response theory. In the quantum limit we find a non-trivial dependence of the induced field and charge distribution on the spatial separation between the clusters and on the frequency of the driving field. Using a genetic algorithm, these quantum functionalities are exploited to custom-design sub-wavelength lenses with a frequency controlled switching capability.Comment: accepted for publication in New Journal of Physic

Mechanics and Mathematical Modeling of Class III Treatment with Orthodontic Appliances with a Movable Ramp

Treatment of class III is a current problem in orthodontics that requires constant improvement of its methods, development of new or modifications of known methods and techniques. We have developed and studied the modification of removable functionally-directing orthodontic appliances for treatment of Class III, which consists of a plastic base, vestibular arc, retaining clasps, ramp, which is connected with the base by means of two torsion springs. Its usage ensures a prolonged contact of ramp with the teeth. We studied two types of club-shaped springs (torsion springs): one spring, which create an amortization effect during the action of the ramp, but do not change its inclination angle and second one – spring that seek to increase the angle of the ramp inclination due to the disclosure of its curl

Investigation of static and dynamic behavior of anisotropic inhomogeneous shallow shells by Spline approximation method

The present report proposes an efficient approach to solving within the framework of the classic and refined models the stress‐strain problems of shallow shells as well as the problems on free vibrations. In accordance with the approach the initial system of partial differential equations is reduced to one‐dimensional problems by using approximation of the solution in terms of basic splines in one coordinate. The boundary‐value problems obtained and eigenvalue boundary‐value problems for systems of ordinary differential high‐order equations are solved by the stable numerical method of discrete ortogonalization. Santrauka Nagrinėjamas efektyvus lėkštųjų kevalų įtempių, deformacijų ir laisvųjų svyravimų nustatymo algoritmas, pagrįstas klasikiniais ir tobulesniais skaičiavimo modeliais. Algoritme dalinių diferencialinių lygčių sistema yra transformuojama į vienmatį uždavinį, sprendžiamą naudojant pagrindinių splainų aproksimaciją į vieną koordinatę. Gaunamas kraštinis uždavinys, kuris sprendžiamas kaip kraštinis savųjų reikšmių nustatymo uždavinys. Uždavinio sąlygas atitinka įprastų aukštesnės eilės diferencialinių lygčių sistema, kuriai spręsti taikomi patikimi diskrečiosios ortogonalizacijos skaitiniai metodai. First Published Online: 14 Oct 2010 Reikšminiai žodžiai: lėkštieji kevalai, kintamasis storis, modifikuotoji ir klasikinė formuluotės, įtempių ir deformacijų būvis, laisvieji svyravimai

MECHANICS AND MATHEMATICAL MODELING OF CLASS III TREATMENT WITH ORTHODONTIC APPLIANCES WITH A MOVABLE RAMP

Treatment of class III is a current problem in orthodontics that requires constant improvement of its methods, development of new or modifications of known methods and techniques. We have developed and studied the modification of removable functionally-directing orthodontic appliances for treatment of Class III, which consists of a plastic base, vestibular arc, retaining clasps, ramp, which is connected with the base by means of two torsion springs. Its usage ensures a prolonged contact of ramp with the teeth.We studied two types of club-shaped springs (torsion springs): one spring, which create an amortization effect during the action of the ramp, but do not change its inclination angle and second one – spring that seek to increase the angle of the ramp inclination due to the disclosure of its curl

Comment on "Negative Refractive Index in Artificial Metamaterials" [A. N. Grigorenko, Opt. Lett., 31, 2483 (2006)]

A key optical parameter characterizing the existence of negative refraction in a thin layer of a composite material is the effective refractive index of an equivalent, homogenized layer with the same physical thickness as the initial inhomogeneous composite. Measuring the complex transmission and reflection coefficients is one of the most rigorous ways to obtain this parameter. We dispute Grigorenko's statement (Optics Letters 31, 2483 (2006)) that measuring only the reflection intensity spectrum is sufficient for determining the effective refractive index. We discuss fundamental drawbacks of Grigorenko's technique of using a best-fit approximation with an a priori prescribed dispersive behavior for a given metamaterial and an 'effective optical thickness' that is smaller than the actual thickness of the sample. Our simulations do not confirm the Grigorenko paper conclusions regarding the negative refractive index and the negative permeability of the nanopillar sample in the visible spectral range.Comment: 18 pages, 7 figure

Bogoliubov angle and visualization of particle-hole mixture in superconductors

Superconducting excitations --Bogoliubov quasiparticles -- are the quantum mechanical mixture of negatively charged electron (-e) and positively charged hole (+e). Depending on the applied voltage bias in STM one can sample the particle and hole content of such a superconducting excitation. Recent Scanning Tunneling Microscope (STM) experiments offer a unique insight into the inner workings of the superconducting state of superconductors. We propose a new observable quantity for STM studies that is the manifestation of the particle-hole dualism of the quasiparticles. We call it a {\em Bogoliubov angle}. This angle measures the relative weight of particle and hole amplitude in the superconducting (Bogoliubov) quasiparticle. We argue that this quantity can be measured locally by comparing the ratio of tunneling currents at positive and negative biases. This Bogoliubov angle allows one to measure directly the energy and position dependent particle-hole admixture and therefore visualize robustness of superconducting state locally. It may also allow one to measure the particle-hole admixture of excitations in normal state above critical temperature and thus may be used to measure superconducting correlations in pseudogap state.Comment: 16 pages, latex file, 9 eps figure

Non-polaritonic effects in cavity-modified photochemistry

Strong coupling of molecules to vacuum fields has been widely reported to lead to modified chemical properties such as reaction rates. However, some recent attempts to reproduce infrared strong coupling results have not been successful, suggesting that factors other than strong coupling may sometimes be involved. Here we re-examine the first of these vacuum-modified chemistry experiments, in which changes to a molecular photoisomerisation process were attributed to strong coupling of the molecules to visible light. We observed significant variations in photoisomerisation rates for molecules placed in a variety of optical cavity structures, but found no evidence that these changes need to be attributed to strong coupling. Instead, we suggest that the photoisomerisation rates involved are most strongly influenced by the absorption of ultraviolet radiation in the cavity. Our results indicate that care must be taken to rule out non-polaritonic effects before invoking strong coupling to explain any changes of chemical properties arising in cavity-based experiments.Comment: 31 pages, 16 figure

Cloning and sequence analysis of cDNA for a human homolog of eubacterial ATP-dependent Lon proteases

AbstractOverlapping cDNA clones containing mRNA for a putative Lon protease (LonHS) were isolated from cDNA libraries prepared from human brain poly(A)+ RNA. The determined nucleotide sequence contains a 2814-bp open reading frame with two potential initiation codons (positions 62–64 and 338–340). The 5'-terminal 337-nucleotide fragment of LonHS mRNA is highly enriched with G and C nucleotides and could direct synthesis of the LonHS N-terminal domain. More likely this region promotes initiation of protein synthesis from the second AUG codon in a cap-independent manner. The amino acid sequence initiated at the second AUG codon includes 845 residues, over 30% of which are identical to those of eubacterial Lon proteases. Residues of the ‘A’ and ‘B’ motifs of NTP-binding pattern and a plausible catalytic serine residue are conserved in LonHS. Northern blot analysis revealed LonHS mRNA in lung, duodenum, liver and heart, but not in thymus cells

STUDY OF ANTI-OSTEOPOROTIC ACTION OF DRUGS FROM THE GROUP OF STATINS

In an experiment on female Wistar white rats, the osteoprotective effect of atorvastatin, simvastatin and rosuvastatin was studied in a model of experimental osteoporosis caused by bilateral ovariectomy. It was found that after ovariectomy in female rats develops endothelial dysfunction, including the vessels of the microcirculatory of the bone, leading to a deterioration of blood supply to bone tissue and the occurrence of osteoporosis. It was found that atorvastatin, simvastatin and rosuvastatin, possessing endothelioprotective activity, prevent deterioration of blood supply to bone tissue and thinning of bone trabeculae, thus having anti-osteoporotic activity. Key words: osteoporosis, endothelial dysfunction, statins, atorvastatin, simvastatin, rosuvastatin, strontium ranelate

Optimization of the design of superconducting inhomogeneous nanowires

We study optimization of superconducting properties of inhomogeneous nanowires. The main goal of this research is to find an optimized geometry that allows one to maximize the desired property of superconductors, such as the maximum value of local superconducting gap or total condensation energy. We consider axially symmetric design of multi-layered nanowires with possibility to adjust and change the layers thickness. We use numerical solution of the Bogoliubov-de Gennes equations to obtain the local superconducting gap for different arrangements of the inhomogeneous structures. The value of the optimized properties can be up to 300% greater compared to a non-optimized geometry. The optimized configuration of multilayers strongly depends on the desired property one wants to optimize and on the number of layers in the nanowire.Comment: Published in J. Phys.: Condens. Matter 20, 195204 (2008