On the entomofauna of Mt. Durmitor (Northern Montenegro): Braconid wasps of the subfamily Opiinae (Braconidae, Hymenoptera)

Braconids are primary parasites of other insects and their eggs, larvae, and adults, and species have been recently discovered that lay their eggs in plant seeds. Classified into about 25 genera, more than 1,400 species of Opiinae are known at the present time in the world fauna. They have been registered in all zoogeographic regions. The Opiinae are solitary endoparasites of the larvae of cyclorhaphous Diptera, most often those of species belonging to the families Agromyzidae, Tephritidae, Anthomyiidae Ephydridae. In investigations conducted on Mt. Durmitor since 1982, we have up to now established 10 species of braconids of the subfamily Opiinae (Opius peterseni Fi., O. caudatus Wesm., O. parvungula Th., O. levisWesm., O. pallipesWesm., O. quasiquisti Fi., O. exilis Hal., O. filicornis Th., O. lugens Hal., and O. meracus Fi), eight of which are new for the fauna of Serbia and Montenegro

EKTOPARAZITI RIBA IZ JEZERA GRADINA, BOSNA I HERCEGOVINA

Tokom proljeća, ljeta i jeseni 2015. provedena je ektoparazitološka studija naribama jezera Gradina, u Bosni i Hercegovini. Osnovni cilj studije bio je otkriti kojeektoparazitske vrste parazitiraju na ribama jezera Gradina. Sekundarni cilj bio jeobjasniti sezonsku dinamiku infestiranosti i intenziteta infestiranosti riba tokomistraživanog perioda. U ukupnom ihtiouzorku od 64 jedinke, determinisano je 5 vrstariba: Alburnus alburnus, Rutilus rutilus, Carassius gibelio, Lepomis gibossus i Abramisbrama. U studiji je determinisano i nekoliko vrsta ektoparazita: Trichodina sp.,Ichthyophthirius multifiliis, Chilodonella sp., Apiosoma sp. i dvije jedinke iz grupeMonogenea. Rezultati istraživanja pokazali su da su najveće vrijednosti infestiranostibile tokom proljeća i ljeta vrstama Trichodina sp. i Ichthyophthirius multifiliis dok jeu jesenskom periodu intenzitet infestiranosti imao niže vrijednosti

Influence of frequency offset on the reception of OFDM/QPSK signal using MBDD algorithm

In this paper we present the basic characteristics of Orthogonal Frequency Division Multiplex (OFDM) systems with quadrature phase shift keying (QPSK) modulation and multi-bit differential detection (MBDD). In the simulation environment designed for this purpose, we analyze the effects of frequency offset on the performances of OFDM digital communications. We also analyze the influence of OFDM system parameters on system performances for various values of frequency offset, number of bits for multi-bit detection and the number of subcarriers. We have shown the advantages and disadvantages of using MBDD in the OFDM systems

Hamiltonian analysis of Poincar\'e gauge theory scalar modes

The Hamiltonian constraint formalism is used to obtain the first explicit complete analysis of non-trivial viable dynamic modes for the Poincar\'e gauge theory of gravity. Two modes with propagating spin-zero torsion are analyzed. The explicit form of the Hamiltonian is presented. All constraints are obtained and classified. The Lagrange multipliers are derived. It is shown that a massive spin-$0^-$ mode has normal dynamical propagation but the associated massless $0^-$ is pure gauge. The spin-$0^+$ mode investigated here is also viable in general. Both modes exhibit a simple type of ``constraint bifurcation'' for certain special field/parameter values.Comment: 28 pages, LaTex, submitted to International Journal of Modern Physics

Spatial distribution of local currents of massless Dirac fermions in quantum transport through graphene nanoribbons

We employ the formalism of bond currents, expressed in terms of the nonequilibrium Green functions, to image the charge flow between two sites of the honeycomb lattice of graphene ribbons of few nanometers width. In sharp contrast to nonrelativistic electrons, current density profiles of quantum transport at energies close to the Dirac point in clean zigzag graphene nanoribbons (ZGNR) differs markedly from the profiles of charge density peaked at the edges due to zero-energy localized edge states. For transport through the lowest propagating mode induced by these edge states, edge vacancies do not affect current density peaked in the center of ZGNR. The long-range potential of a single impurity acts to reduce local current around it while concurrently increasing the current density along the zigzag edge, so that ZGNR conductance remains perfect $G=2e^2/h$.Comment: 5 pages, 5 figure

Humidity sensing properties of nanocrystalline pseudobrookite (Fe2TiO5) based thick films

Pseudobrookite based nanopowder was obtained by solid state synthesis of starting hematite and anatase nanopowders in the weight ratio 55:45. Structural and morphological properties were analyzed using X-ray diffraction (XRD), BET, X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, UV/Vis diffuse reflectance spectroscopy, Field emission scanning electron microscopy (FESEM) and Transmission electron microscopy (TEM) confirming the formation of nanocrystalline pseudobrookite. The obtained powder was mixed with a binder (ethyl cellulose), dispersant (alpha-terpinol) and adhesion agents (acetic acid and distilled water) to obtain a thick film paste. It was screen printed on alumina substrate with interdigitated PdAg electrodes and fired at 600 degrees C for 30 min. Formation of a porous nanocrystalline thick film structure was shown using Scanning electron microscopy (SEM), while Hall measurements enabled determination of carrier mobility. Change of impedance response in the frequency range 42 Hz-1 MHz with humidity was analyzed at room temperature (25 degrees C) and 50 degrees C in the relative humidity range 30-90% and 40-90%, respectively. At 42 Hz, and room temperature the impedance reduced similar to 28 times, while at 50 degrees C it reduced similar to 147 times in the relative humidity range 40-90%. The sensor showed rapid response (16 s) and relatively low hysteresis (8.39% at 25 degrees C and 2.64% at 50 degrees C) showing that this is a promising material for application in humidity sensing

Synthesis of Samarium and Zirconium-doped TiO2 nanofibers with improved photocatalytic activity

Samarium and zirconium-doped TiO2 nanofibers (3 and 5 wt.%) were synthesised by a simple modified electrospinning method. The effects of calcination temperature on the size of the as-spun doped titania fibers was investigated. As-spun nanofibers were studied and characterized through thermal gravimetric analysis (TG-DTA), Fourier Transform Infrared Spectroscopy (FTIR) and Scanning electron microscopy (SEM), while the structure and morphology of calcined fibers was studied by X-Ray Diffraction (XRD), Field Emission Electron Microscopy (FESEM) and spectroscopic techniques (FT-IR and DRS UV-vis). The influence of dopant type and amount on the photocatalytic degradation of Methylene blue (MB) was investigated

Effect of transport-induced charge inhomogeneity on point-contact Andreev reflection spectra at ferromagnet-superconductor interfaces

We investigate the transport properties of a ferromagnet-superconductor interface within the framework of a modified three-dimensional Blonder-Tinkham-Klapwijk formalism. In particular, we propose that charge inhomogeneity forms via two unique transport mechanisms, namely, evanescent Andreev reflection and evanescent quasiparticle transmission. Furthermore, we take into account the influence of charge inhomogeneity on the interfacial barrier potential and calculate the conductance as a function of bias voltage. Point-contact Andreev reflection (PCAR) spectra often show dip structures, large zero-bias conductance enhancement, and additional zero-bias conductance peak. Our results indicate that transport-induced charge inhomogeneity could be a source of all these anomalous characteristics of the PCAR spectra.Comment: 9 pages, 6 figure