Pure scaling operators at the integer quantum Hall plateau transition

Stationary wave functions at the transition between plateaus of the integer quantum Hall effect are known to exhibit multi-fractal statistics. Here we explore this critical behavior for the case of scattering states of the Chalker-Coddington model with point contacts. We argue that moments formed from the wave amplitudes of critical scattering states decay as pure powers of the distance between the points of contact and observation. These moments in the continuum limit are proposed to be correlations functions of primary fields of an underlying conformal field theory. We check this proposal numerically by finite-size scaling. We also verify the CFT prediction for a 3-point function involving two primary fields.Comment: Published version, 4 pages, 3 figure

Mammals of the World: MaNIS as an example of data integration in a distributed network environment

Natural history collections are the authoritative source of knowledge about the identity, evolutionary relationships, and attributes of species with which we share this planet. As such, collections of research specimens play a central and critical role in the conservation and sustainable use of biodiversity. The potential contribution of specimen data to systematic, genomic, and ecological analyses is enormous, and will be orders of magnitude greater when information is made easily accessible via distributed networks compared with stand-alone database systems in use up to the present. The Mammal Networked Information System (MaNIS) is a distributed database network that permits participating institutions to provide web-based global access to their collections data for research, education and informed decision-making. The simplicity of the network’s design ensures that any institution wishing to join MaNIS may do so at relatively little cost and with relatively little technical expertise. Although development of MaNIS and its underlying architecture relied on a number of key programming tasks and innovations, much of what the project can offer at this pivotal juncture is insight into its approach and a template by which other disciplines can engage in a similar process with equal success

Identifikacija i iskorištavanje cestovne prašine

The aim of this publication is to determine models of explore dust from vehicle brake systems and the presentationof measurement results of the exploitation dust, which is separate from road dust. The following methods and measuring devices were used: T-01M device, screen analysis, analysis of chemical composition with the use of a scanning microscope with Energy Dispersive x-ray Spectroscopy (EDS) analyser. The measurements for identifying this type of dust were conducted on marked sections of roads: motorway, city road and mountain road. The explored dust was distinguished in the following car systems: brakes, clutch plates, tyres and catalytic converters.Cilj ove publikacije je utvrditi modele upotrebe prašine, koja je odvojena od cestovne prašine. Za ispitivanje su korištene sljedeće metode i mjerni uređaji: T-01M uređaj, granulometrijska analiza i upotreba pretražnog elektronskog mikroskopa s energetsko disperzijskim spektrometrom. Za mjerenja su uzeti uzroci prašine na različititim dijelovima ceste: autoceste, gradske i planinske ceste. Istraživana prašina potječe od sljedećih dijelova automobila, kočnice, spojke, gume i katalizatora

Charged Particle with Magnetic Moment in the Aharonov-Bohm Potential

We considered a charged quantum mechanical particle with spin ${1\over 2}$ and gyromagnetic ratio $g\ne 2$ in the field af a magnetic string. Whereas the interaction of the charge with the string is the well kown Aharonov-Bohm effect and the contribution of magnetic moment associated with the spin in the case $g=2$ is known to yield an additional scattering and zero modes (one for each flux quantum), an anomaly of the magnetic moment (i.e. $g>2$) leads to bound states. We considered two methods for treating the case $g>2$. \\ The first is the method of self adjoint extension of the corresponding Hamilton operator. It yields one bound state as well as additional scattering. In the second we consider three exactly solvable models for finite flux tubes and take the limit of shrinking its radius to zero. For finite radius, there are $N+1$ bound states ($N$ is the number of flux quanta in the tube).\\ For $R\to 0$ the bound state energies tend to infinity so that this limit is not physical unless $g\to 2$ along with $R\to 0$. Thereby only for fluxes less than unity the results of the method of self adjoint extension are reproduced whereas for larger fluxes $N$ bound states exist and we conclude that this method is not applicable.\\ We discuss the physically interesting case of small but finite radius whereby the natural scale is given by the anomaly of the magnetic moment of the electron $a_e=(g-2)/2\approx 10^{-3}$.Comment: 16 pages, Latex, NTZ-93-0

Hallmarks of mechanochemistry: From nanoparticles to technology

The aim of this review article on recent developments of mechanochemistry (nowadays established as a part of chemistry) is to provide a comprehensive overview of advances achieved in the field of atomistic processes, phase transformations, simple and multicomponent nanosystems and peculiarities of mechanochemical reactions. Industrial aspects with successful penetration into fields like materials engineering, heterogeneous catalysis and extractive metallurgy are also reviewed. The hallmarks of mechanochemistry include influencing reactivity of solids by the presence of solid-state defects, interphases and relaxation phenomena, enabling processes to take place under non-equilibrium conditions, creating a well-crystallized core of nanoparticles with disordered near-surface shell regions and performing simple dry time-convenient one-step syntheses. Underlying these hallmarks are technological consequences like preparing new nanomaterials with the desired properties or producing these materials in a reproducible way with high yield and under simple and easy operating conditions. The last but not least hallmark is enabling work under environmentally friendly and essentially waste-free conditions (822 references).Slovak Grant Agency VEGA 2/0009/11, 2/0043/11Slovak Agency for Science and Development APVV VV-0189-10, VV-0528-11Russian Foundation for Basic Research 10-03-00942a, 12-03-00651aMinistry of Science and Higher education in Poland CUT/c-1/DS/KWC/2008-2012, PB1T09B02330, NN209145136, NN20914893

Tensile strained InxGa1−xPIn_{x}Ga_{1-x}P membranes for cavity optomechanics

We investigate the optomechanical properties of tensile-strained ternary InGaP nanomembranes grown on GaAs. This material system combines the benefits of highly strained membranes based on stoichiometric silicon nitride, with the unique properties of thin-film semiconductor single crystals, as previously demonstrated with suspended GaAs. Here we employ lattice mismatch in epitaxial growth to impart an intrinsic tensile strain to a monocrystalline thin film (approximately 30 nm thick). These structures exhibit mechanical quality factors of 2*10^6 or beyond at room temperature and 17 K for eigenfrequencies up to 1 MHz, yielding Q*f products of 2*10^12 Hz for a tensile stress of ~170 MPa. Incorporating such membranes in a high finesse Fabry-Perot cavity, we extract an upper limit to the total optical loss (including both absorption and scatter) of 40 ppm at 1064 nm and room temperature. Further reductions of the In content of this alloy will enable tensile stress levels of 1 GPa, with the potential for a significant increase in the Q*f product, assuming no deterioration in the mechanical loss at this composition and strain level. This materials system is a promising candidate for the integration of strained semiconductor membrane structures with low-loss semiconductor mirrors and for realizing stacks of membranes for enhanced optomechanical coupling.Comment: 10 pages, 3 figure

Бароосмотичний аналіз як новий метод гідрогеологічних досліджень

Запропоновано методику бароосмотичного аналiзу гiдрогеологiчних даних для окремих свердловин, за якою визначаються величина бароосмотичного напору H2O у пластових (порових) водах i ступiнь вiдхилення їх вiд стану бароосмотичної рiвноваги на кiлькох водоносних горизонтах. Результати аналiзу для чотирьох свердловин з рiзних регiонiв пiдтвердили iснування вертикальних бароосмотичних потокiв у глинистих товщах усiх розрiзiв i дали змогу визначити напрями цих потокiв та виявити зони впливу особливих локальних гiдрогеологiчних процесiв.Methods of baroosmotic analysis of hydrogeological data for separate boreholes have been proposed. They can be applied to determine the baroosmotic pressure of H2O in formational (porous) waters and the degree of their defection from the state of baroosmotic balance at several water-bearing horizons. The results of analysis conducted at 4 boreholes from different regions have confirmed the existence of vertical baroosmotic flows in clayey units of all sections and have allowed us to determine the directions of these flows and to reveal the zones affected by specific local hydrogeological processes

VertNet: A New Model for Biodiversity Data Sharing

Responding to the urgent need to make biodiversity records broadly accessible, the natural history community turned to “the cloud.