A dynamic localization of 2D electrons at mesoscopic length scales

We have investigated the local magneto-transport in high-quality 2D electron systems at low carrier densities. The positive magneto-resistance in perpendicular magnetic field in the strongly insulating regime has been measured to evaluate the spatial concentration of localized states within a mesoscopic region of the samples. An independent measurement of the electron density within the same region shows an unexpected correspondence between the density of electrons in the metallic regime and that of the localized states in the insulating phase. We have argued that this correspondence manifests a rigid distribution of electrons at low densities.Comment: 8 pages (incl 4 figures), double colum

Newton-Kantorovich Iterative Regularization for Nonlinear Ill-Posed Equations Involving Accretive Operators

The Newton-Kantorovich iterative regularization for nonlinear ill-posed equations involving monotone operators in Hilbert spaces is developed for the case of accretive operators in Banach spaces. An estimate for the convergence rates of the method is established.Розроблено ітераційну регулярнзацію Ньютона - Канторовича для нелінійних некоректних рівнянь з монотонним оператором у гільбертових просторах для випадку акретивного оператора в банахових просторах. Встановлено оцінки швидкостей збіжності методу

Влияние размера частиц политетрафторэтилена на свойства композитов на основе сверхвысокомолекулярного полиэтилена

С целью исследования влияния дисперсности наполнителя на структуру, механические и триботехнические свойства композиционных материалов на основе сверхвысокомолекулярного полиэтилена (СВМПЭ), был использован политетрафторэтилен (PTFE) с различными размерами. Экспериментальные результаты показали, что при добавлении маленького наполнителя (Ø 10 мкм) структура композитов более однородная, механические свойства снижаются меньше и износостойкость при сухом трении скольжения выше в 2 раза, чем при добавлении большого наполнителя (Ø 100-180 мкм). Указано оптимальное содержание наполнителя для повышения износостойкости композитов на основе СВМПЭ. Полученные результаты обсуждались чтобы преодолеть ограничения структуры и относительного удлинения, предел прочности при растяжении композитов

Magnetotransport in disordered delta-doped heterostructures

We discuss theoretically how electrons confined to two dimensions in a delta-doped heterostructure can arrange themselves in a droplet-like spatial distribution due to disorder and screening effects when their density is low. We apply this droplet picture to magnetotransport and derive the expected dependence on electron density of several quantities relevant to this transport, in the regimes of weak and moderate magnetic fields. We find good qualitative and quantitative agreement between our calculations and recent experiments on delta-doped heterostructures.Comment: 10 pages RevTeX, 2 figures, uses psfrag; published versio

Approximate hedging problem with transaction costs in stochastic volatility markets

This paper studies the problem of option replication in general stochastic volatility markets with transaction costs, using a new specification for the volatility adjustment in Leland's algorithm. We prove several limit theorems for the normalized replication error of Leland's strategy, as well as that of the strategy suggested by Lépinette. The asymptotic results obtained not only generalize the existing results, but also enable us to fix the underhedging property pointed out by Kabanov and Safarian. We also discuss possible methods to improve the convergence rate and to reduce the option price inclusive of transaction costs

Sequence Analysis of Inducible Prophage phIS3501 Integrated into the Haemolysin II Gene of Bacillus thuringiensis var israelensis ATCC35646

Diarrheic food poisoning by bacteria of the Bacillus cereus group is mostly due to several toxins encoded in the genomes. One of them, cytotoxin K, was recently identified as responsible for severe necrotic syndromes. Cytotoxin K is similar to a class of proteins encoded by genes usually annotated as haemolysin II (hlyII) in the majority of genomes of the B. cereus group. The partially sequenced genome of Bacillus thuringiensis var israelensis ATCC35646 contains several potentially induced prophages, one of them integrated into the hlyII gene. We determined the complete sequence and established the genomic organization of this prophage-designated phIS3501. During induction of excision of this prophage with mitomycin C, intact hlyII gene is formed, thus providing to cells a genetic ability to synthesize the active toxin. Therefore, this prophage, upon its excision, can be implicated in the regulation of synthesis of the active toxin and thus in the virulence of bacterial host. A generality of selection for such systems in bacterial pathogens is indicated by the similarity of this genetic arrangement to that of Staphylococcus aureus  β-haemolysin

Biophysical Insights into Peptide and Alcohol Perturbations on Biomimetic Membranes

Biological membranes exist in every domain of life. Life exists due to the presence of these special structures for which we take for granted. They are composed of fatty lipids and workhorse proteins and act as the premier interface of biological processes. Due to the sheer quantity and complexity within their thin boundary, studying their actions and properties pose challenges to researchers. As a result, simplified biomembrane mimics are employed regularly. We will use several types of biomembrane mimics to understand fundamental properties of membranes. In the present thesis, we also attempt to move beyond the canonical structure-based theories upon which a majority of biophysical studies are predicated upon. This has been the case as structural quantities still greatly inform on the conditions of the bilayer system, yet the exact lipid distribution and movement are less studied. We will focus upon the movement and organization of phospholipids using a bounty of biophysical techniques, such as small angle neutron scattering, molecular dynamics, and more. The results will be interpreted to show how phospholipid mobility fits into the greater membrane framework

Coulomb Glasses: A Comparison Between Mean Field and Monte Carlo Results

Recently a local mean field theory for both eqilibrium and transport properties of the Coulomb glass was proposed [A. Amir et al., Phys. Rev. B 77, 165207 (2008); 80, 245214 (2009)]. We compare the predictions of this theory to the results of dynamic Monte Carlo simulations. In a thermal equilibrium state we compare the density of states and the occupation probabilities. We also study the transition rates between different states and find that the mean field rates underestimate a certain class of important transitions. We propose modified rates to be used in the mean field approach which take into account correlations at the minimal level in the sense that transitions are only to take place from an occupied to an empty site. We show that this modification accounts for most of the difference between the mean field and Monte Carlo rates. The linear response conductance is shown to exhibit the Efros-Shklovskii behaviour in both the mean field and Monte Carlo approaches, but the mean field method strongly underestimates the current at low temperatures. When using the modified rates better agreement is achieved