On Bright and Dark Breathers in Lattices with Saturable Nonlinearity

The moving bright and dark localized modes in one-dimensional optical lattices with saturable nonlinearity are considered with respect to the grand canonical free energy concept and linear stability analysis of the eigenvalue spectra

Saturable discrete vector solitons in one-dimensional photonic lattices

Localized vectorial modes, with equal frequencies and mutually orthogonal polarizations, are investigated both analytically and experimentally in a one-dimensional photonic lattice with saturable nonlinearity. It is shown that these modes may span over many lattice elements and that energy transfer among the two components is both phase and intensity dependent. The transverse electrically polarized mode exhibits a single-hump structure and spreads in cascades in saturation, while the transverse magnetically polarized mode exhibits splitting into a two-hump structure. Experimentally such discrete vector solitons are observed in lithium niobate lattices for both coherent and mutually incoherent excitations.Comment: 4 pages, 5 figures (reduced for arXiv

Poboljšanje proizvodnih osobina domaće šarenog govečeta korišćenjem bikova Monbelijar rase

Improvement of breed structure of cattle, that is improvement of their production performance and characteristics, as well as phenotype, is main task of centers for artificial insemination and expert services. During the period 1992 - 2000, in Republic of Serbia, 8 Montbeliard bulls were active in AI Centre Krnjača. Bulls originated from Montbeliard heifers imported from France into Negotin region. Bulls were raised, exploited in AI Centre Krnjača and tested on the territory of the Republic. Of total 8 bulls, 6 completed progeny testing and for 2 bulls test is ongoing. Testing was carried out by A control compared to Simmental bulls used and tested in identical conditions and under same criteria. Results of the test concerning milkiness are higher by 296 l, and lower by O,54% for milk fat. Exterior traits in average are increased with the exception of body mass that is in average lower by 16 kg.Poboljšanje rasnog sastava goveda, odnosno poboljšanje njihovih proizvodnih osobina, eksterijernih karakteristika i fenotipa je osnovni zadatak centara za veštačko osemenjavanje i stručnih službi. U periodu od 1992. - 2000. godine u Republici Srbiji delovalo je 8 bikova Monbelijar rase iz centra za veštačko osemenjavanje u Krnjači. Bikovi su dobijeni od uvezenih priplodnih junica monbelijar rase iz Francuske u region Negotina. Bikovi su odgajeni eksploatisani u centru Krnjača i testirani na području Republike. Od ukupno 8 bikova, 6 je završilo progeni test, a za 2 je test u toku. Test je rađen A kontrolom u odnosu na bikove simentalske rase korišćene i testirane u istim uslovima i po istim kriterijumima.Rezultati testa na mlečnost su veći za 296 litara, a mlečne masti manji za 0,54 %. Eksterijerne mere su u proseku u povećanju osim težine koja je manja za prosečno 16 kg

Management of roe deer population (Capreolus capreolus L.) in Serbia

ABSTRACT The research was conducted during the 2018/19 hunting year at three hunting grounds: "Barajevska reka" - "Takovo" and "Jadar". The average density of Roe deer in hunting grounds varied from 48.67 to 74 individuals per 1,000 ha of hunting-productive area. However, when observing the number of individuals per 1,000 ha of total hunting area, the density varies from 16.07 individuals to 34.72 individuals. The determined gender ratio at the hunting ground "Jadar" was (M: F = 1: 0.93). At the hunting ground "Takovo", the gender ratio was (M: F = 1: 1.22), while at the hunting ground "Barajevska reka" the ratio was (M: F = 1: 1.59). The average fertility of Roe deer was 1.67 embryos per individual, or 1.75 embryos per pregnant female. Depending on the study area, the real growth varied from 0.54 to 0.73 fawns per female. Loss in Roe deer are caused mostly by biotic factors. The determined average age of shot individuals varied depending on the hunting ground from 3.53 to 5.24 years. The current state of Roe deer populations in Serbia varies between analyzed hunting grounds, but the overall situation is quite unsatisfactory, especially in terms of density, gender ratio and age structure of culled individuals

Strong coupling regime of semiconductor quantum dot embedded in the nano-cavity

Photonic lattices represent suitable systems for investigation of wave propagation in periodic structures [1]. However, different unavoidable defects may arise either during their process of fabrication or as result of misusage, accidental damage, etc. Although undesirable in the first place, these imperfections enable the existence of different types of stable, localized defect modes [2]. In this paper, we investigate light propagation through composite photonic lattice composed of two identical linear and lossless lattices. The interface between them represents a geometric defect, while each lattice contains a single nonlinear defect that is placed symmetrically with respect to the interface. Depending on the input light beam parameters (its position, width and transverse tilt), the width of geometric defect, strength and position of the nonlinear defects, different dynamical regimes have been identified. These dynamical regimes are caused by the balance of photonic lattice potentials’ contributions originating from the presence of the geometric and two nonlinear defects. We have found numerically conditions under which dynamically stable bounded modes can exist in the area between nonlinear defects or between a nonlinear and a geometric defect. Various types of localized modes such as: two-hump, multi-hump, one- and multicomponent moving breathers localized at a certain area among defects have been observed. The parameters can be adjusted to capture light and to prevent light launched inside the area among defects to leave it, i.e. this corresponds to the appearance of the modes trapped inside this area. Since the configuration of the lattice prevents transmission of the light through the area confined by defects, these modes can formally be related to Fano resonances and Fano- blockade [3, 4]. When light is launched outside the area among defects, different dynamical regimes have been distinguished: total reflection, single and double partial reflection and full transmission through the area among defects. These numerical findings may lead to interesting applications such as blocking, filtering and transporting light beams through the optical medium. Photonic devices based on resonant tunneling such as waveguides interacting through the area between defects, may be applied as add-drop filters.V International School and Conference on Photonics and COST actions: MP1204, BM1205 and MP1205 and the Second international workshop "Control of light and matter waves propagation and localization in photonic lattices" : PHOTONICA2015 : book of abstracts; August 24-28, 2015; Belgrad

Localized modes in two-dimensional octagonal-diamond lattices

Two-dimensional octagonal-diamond (OD) atomic lattices have been explored in recent times to study phenomena related to topological phase transitions induced by spin-orbit interaction and gauge fields [1], and magnetic phases and metal-insulator transitions with Hubbard interaction [2, 3]. It can lead to the appearance of nontrivial nearly flat band states with particular topological properties [4]. Here we study the octagonal-diamond photonic lattice formed of linearly coupled waveguides, proposed by [4] as a possible experimental realization of an artificial flat-band system. We investigated analytically and numerically the existence and stability of linear and nonlinear localized modes in a two-dimensional OD lattice. The primitive cell consists of four sites, linearly coupled with each other with the same coupling constant, including two diagonal couplings. The eigenvalue spectrum of the linear lattice consists of two flat bands and two dispersive bands [4]. The upper dispersive band intersects the upper flat band in the middle of the Brillouin zone, as well as the second flat band at the end of the Brillouin zone. In the linear case, there are two types of localized linear solutions, which are composed of eight sites each, having either monomer (+ - + - + - + -) or dimer (+ + - - + + - -) staggered phase structure [4]. In the presence of Kerr nonlinearity, both focusing and defocusing, compacton-like solutions [5] may exhibit instabilities due to intersections of the upper dispersive band and the flat bands. We also discuss the possibility of finding soliton solutions in the frequency gaps occurring between the flat bands and the isolated dispersive bands.VII International School and Conference on Photonics : PHOTONICA2019 : Abstracts of Tutorial, Keynote, Invited Lectures, Progress Reports and Contributed Papers; August 26-30; Belgrad

Photosensitizer potential of doped and undoped nanostructured TiO2

Treating cancer remains a major challenge, despite the development of many therapies and advances in general knowledge about the disease. The treatments commonly used are invasive and non-selective, leading to severe side effects and unsatisfactory long-term outcomes. Nevertheless, external stimuli activating therapeutic agents in the affected area can be more beneficial than these aggressive therapies. Photodynamic therapy (PDT) is a minimally invasive, selective treatment that uses photosensitizer (PS) to damage cancer cells. The PS is activated by light, triggering a series of processes that produce reactive oxygen species (ROS), ultimately leading to cancer cell death. Numerous types of nanomaterial possess the capability to act as PS, one of which is TiO2 [1]. Although nanostructured TiO2 is biocompatible in the absence of light, its valence band electrons can be stimulated only by ultraviolet (UV) light irradiation. Since the penetration of UV light into tissue is limited, for application in PDT, nanostructured TiO2 can be doped with heteroatoms like N or C to allow visible light responsiveness [2,3]. This work evaluated the PS properties of unmodified nanostructured TiO2 (spherical nanoparticles TiO2 NPs and prolate nanospheroids, TiO2 PNSs) and doped TiO2 (N- and C-TiO2 NPs). After the synthesis, the size of TiO2 was confirmed to be in the nanoscale range (5-104 nm) by transmission electron microscopy [3,4]. The doped TiO2 was found to absorb visible light, as demonstrated by UV-Vis spectroscopy and bandgap calculations. Additionally, hydroxyl radicals were detected in water suspensions of TiO2 PNSs by electron paramagnetic resonance (EPR) spectroscopy, both with and without UV light illumination [4]. However, this radical was observed only with blue light stimulation of the water suspensions of N- and C-TiO2 NPs [3]. Cell experiments further revealed the internalization process of nanostructured TiO2 within cells, their cytotoxicity profiles, and the different death modalities triggered by their uptake. After confocal microscopy indicated the successful internalization of the investigated TiO2, viability tests on different cell lines confirmed their good biocompatibility without light [3,4]. The PDT's efficacy using nanostructured TiO2 and appropriate light stimuli was evaluated on various cancer cell lines. The most significant viability reduction (60 %) was observed in the HeLa cell line with the combined treatment of C-TiO2 NPs-blue light. In addition to EPR results, blue light-induced C-TiO2 NPs-catalyzed generation of ROS was confirmed intracellularly, implying that oxidative stress was the leading cause of HeLa cell death. Fluorescent labeling allowed distinguishing morphological changes inside the cells after the C-TiO2 NPs, blue light, and the combined C-TiO2 NPs-blue light treatment. Blue light exposure led to the appearance of large necrotic cells with deformed nuclei, cytoplasm swelling, and membrane blebbing. In contrast, the combined therapy with C-TiO2 NPs-blue light resulted in controlled cell death, such as autophagy. Since programmed cell death is the desired cancer cell death mechanism, the combined treatment presented here can provide a better outcome of local anticancer therapy.IX International School and Conference on Photonics : PHOTONICA2023 : book of abstracts; August 28 - September 1, 2023; Belgrad

The importance of buffalo in milk production and buffalo population in Serbia

This research paper gives an analysis on the size of world's domestic buffalo populations, their milk production and the size of buffalo population in Serbia. Population of domestic buffalo in the world is constantly increasing so that in 2013 there were 199 783 549 individuals, out of which in India in the same year they raised 57.77% of buffalo world population, in Pakistan 18.87%, and in China 11.64%. The share of total world production of buffalo milk in total world milk production in 2012 was 12.92 % or 97 417 135 t out of which 67.76% was produced in India. In Serbia buffalo is raised in the regions of Raška (about 1000 individuals) and Kosovo. Populations of buffalo in central Serbia show a tendency of decreasing in size what was the reason to start a programme of in situ conservation 10 years ago. On the sample of buffalo population encompassed by the programme of conservation the body measures were analysed indicating that the population of buffalo is quite unequalised and that average values obtained for exterior measures are similar to the results obtained by the authors of earlier period for the population of buffalo in the area of former Yugoslavia

Doubly periodic waves of a discrete nonlinear Schr\"odinger system with saturable nonlinearity

A system of two discrete nonlinear Schr\"odinger equations of the Ablowitz-Ladik type with a saturable nonlinearity is shown to admit a doubly periodic wave, whose long wave limit is also derived. As a by-product, several new solutions of the elliptic type are provided for NLS-type discrete and continuous systems.Comment: 12 pages, to appear, Journal of nonlinear mathematical physic