Proposal for a Mesoscopic Optical Berry-Phase Interferometer

We propose a novel spin-optronic device based on the interference of polaritonic waves traveling in opposite directions and gaining topological Berry phase. It is governed by the ratio of the TE-TM and Zeeman splittings, which can be used to control the output intensity. Because of the peculiar orientation of the TE-TM effective magnetic field for polaritons, there is no analogue of the Aharonov- Casher phase shift existing for electrons.Comment: 4 page

Pseudospin dynamics in multimode polaritonic Josephson junctions

We analyzed multimode Josephson junctions with exciton-polaritons (polaritonic Josephson junctions) when several coupling mechanisms of fundamental and excited states are present. The applied method is based on Keldysh-Green function formalism and takes into account polariton pseudospin. We found that mean value of circular polarization degree in intrinsic Josephson oscillations and microscopic quantum self-trapping follow an oscillator behavior whose renormalizes due to intermode interactions. The effect of an additional transfer of particles over junction barrier occurring in multimode approximation in combination with common Josephson tunneling is discussed in regime of dynamical separation of two polarizations.Comment: 12 pages, 4 figure

Decolorization of reactive violet 5 dye in textile wastewater by electrocoagulation

The textile dyeing industry consumes large quantities of water and produces large volumes of wastewater from different steps in the dyeing and finishing processes. Wastewater from printing and dyeing units is often rich in color, containing residues of reactive dyes and chemicals, such as complex components. This study investigates the decolorization of synthetic dye wastewater containing textile dye Reactive Violet 5 (RV5) by electrocoagulation. A laboratory batch reactor was used to investigate the effect of various operating parameters using aluminium (Al), iron (Fe) and stainless steel (SS) anode. The effect of dye concentration, current density, supporting electrolyte, sup-porting electrolyte concentration, electrolysis duration, and material of anode of the systems were evaluated. Color removal efficiency was 22, 91.5 and 99.8 % in 15 minutes using Al, Fe and SS anode, respectively (j = 10 mA/cm2, cNaCl = 0.171 M)

High School Class for Gifted Pupils in Physics and Sciences and Pupils` Skills Measured by Standard and Pisa Test

The ``High school class for students with special abilities in physics`` was founded in Nis, Serbia in 2003. The basic aim of this project has been introducing a broadened curriculum of physics, mathematics, computer science, as well as chemistry and biology. We present analysis of the pupils` skills in solving rather problem oriented test, as PISA test, and compare their results with the results of pupils who study under standard curricula. Analysis of achievement data should clarify what are benefits of introducing in school system track for gifted students. Additionally, item analysis helps in understanding and improvement of learning strategies efficacy.Comment: 6 pages, Talk given at 7th International Conference of the Balkan Physical Union, Alexandruoplos, Greece, 9-13 September 2009. To be published in AIP Conf.Pro

Dispersion and polarization conversion of whispering gallery modes in arbitrary cross-section nanowires

We investigate theoretically the optical properties of Nano-Wires (NWs) with cross sections having either discrete or cylindrical symmetry. The material forming the wire is birefringent, showing a different dielectric response in the plane and along the axis of the wire, which is typically the case for wires made of wurtzite materials, such as ZnO or GaN. We look for solutions of Maxwell`s equations having the proper symmetry. The dispersions and the linewidths versus angle of incident light for the modes having high momentum in the cross-section plane, so called whispering gallery modes, are calculated. We put a special emphasis on the case of hexagonal cross sections. The energy positions of the modes for a set of azimuthal quantum numbers are shown. We demonstrate the dependence of the energy splitting between TE and TM modes versus birefringence. The polarization conversion from TE to TM with increase of the axial wave vectoris discussed for both cylindrical and discrete symmetry.Comment: 9 pages, 10 figure

Acid aging effects on surfaces of PTFE gaskets investigated by thermal analysis

This paper investigates the effect of a prolonged acid attack on the surface of PTFE by Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC). PTFE is very non-reactive, partly because of the strength of carbon\u2013fluorine bonds and for its high crystallinity, and, as a consequence, it is often used in containers and pipework with reactive and corrosive chemicals. The PTFE under analysis is commercialized by two alternative producers in form of Teflon tapes. These tapes are adopted, as gaskets, in process plants where tires moulds are cleaned by acid solutions inside a multistage ultrasonic process. In this case, PTFE shows, in a relatively short operation time, inexplicably phenomena of surface degradation, which could be related, in general terms, to an acid attack. But, even considering the combined effect of ultrasonic waves, temperature, humidity and acid attack, the PTFE properties of resistance nominally exclude the risk of the extreme erosion phenomena as observed. The present experimental research aim at investigating this contradiction. A possible explanation could be related to the presence in the cleaning solution of unexpected fluorides, able to produce fluorinating agents and, thus, degrade carbon-fluorine bonds. Considering more the 300 chemical elements a tire compound consists in, it is really complex to preserve the original chemical composition of the cleaning solution. In this research PTFE samples have been treated with different mixtures of acids with the aim at investigating the different aging effects. The thermal analysis has permitted the experimental characterization of PTFE surface properties after acid attack, providing evidence of the degradation phenomena. In particular, the different acid treatments adopted for accelerating the aging of gaskets have highlighted the different behaviour of the PTFE matrix, but also differences between manufacturers

A Splicing Mutation in the Novel Mitochondrial Protein DNAJC11 Causes Motor Neuron Pathology Associated with Cristae Disorganization, and Lymphoid Abnormalities in Mice

Mitochondrial structure and function is emerging as a major contributor to neuromuscular disease, highlighting the need for the complete elucidation of the underlying molecular and pathophysiological mechanisms. Following a forward genetics approach with N-ethyl-N-nitrosourea (ENU)-mediated random mutagenesis, we identified a novel mouse model of autosomal recessive neuromuscular disease caused by a splice-site hypomorphic mutation in a novel gene of unknown function, DnaJC11. Recent findings have demonstrated that DNAJC11 protein co-immunoprecipitates with proteins of the mitochondrial contact site (MICOS) complex involved in the formation of mitochondrial cristae and cristae junctions. Homozygous mutant mice developed locomotion defects, muscle weakness, spasticity, limb tremor, leucopenia, thymic and splenic hypoplasia, general wasting and early lethality. Neuropathological analysis showed severe vacuolation of the motor neurons in the spinal cord, originating from dilatations of the endoplasmic reticulum and notably from mitochondria that had lost their proper inner membrane organization. The causal role of the identified mutation in DnaJC11 was verified in rescue experiments by overexpressing the human ortholog. The full length 63 kDa isoform of human DNAJC11 was shown to localize in the periphery of the mitochondrial outer membrane whereas putative additional isoforms displayed differential submitochondrial localization. Moreover, we showed that DNAJC11 is assembled in a high molecular weight complex, similarly to mitofilin and that downregulation of mitofilin or SAM50 affected the levels of DNAJC11 in HeLa cells. Our findings provide the first mouse mutant for a putative MICOS protein and establish a link between DNAJC11 and neuromuscular diseases

Entangled photon pairs produced by a quantum dot strongly coupled to a microcavity

We show theoretically that entangled photon pairs can be produced on demand through the biexciton decay of a quantum dot strongly coupled to the modes of a photonic crystal. The strong coupling allows to tune the energy of the mixed exciton-photon (polariton) eigenmodes, and to overcome the natural splitting existing between the exciton states coupled with different linear polarizations of light. Polariton states are moreover well protected against dephasing due to their lifetime ten to hundred times shorter than that of a bare exciton. Our analysis shows that the scheme proposed can be achievable with the present technology

Modelling and analyzing adaptive self-assembling strategies with Maude

Building adaptive systems with predictable emergent behavior is a challenging task and it is becoming a critical need. The research community has accepted the challenge by introducing approaches of various nature: from software architectures, to programming paradigms, to analysis techniques. We recently proposed a conceptual framework for adaptation centered around the role of control data. In this paper we show that it can be naturally realized in a reflective logical language like Maude by using the Reflective Russian Dolls model. Moreover, we exploit this model to specify and analyse a prominent example of adaptive system: robot swarms equipped with obstacle-avoidance self-assembly strategies. The analysis exploits the statistical model checker PVesta

Electric generation of vortices in an exciton-polariton superfluid

We have theoretically demonstrated the on demand electric generation of vortices in an exciton-polariton superfluid. Electric pulses applied to a horseshoe-shaped metallic mesa, deposited on top of the microcavity, generate a non-cylindrically symmetric solitonic wave in the system. Breakdown of its wavefront at focal points leads to the formation of vortex-antivortex pairs which subsequently propagate in the superfluid. The trajectory of these vortex dipoles can be controlled by applying a voltage to additional electrodes. They can be confined within channels formed by metallic stripes and unbound by a wedged mesa giving birth to grey solitons. Finally single static vortices can be generated using a single metallic plate configuration.Comment: 7 pages and 7 figure