Generation and stability of discrete gap solitons

We analyze stability and generation of discrete gap solitons in weakly coupled optical waveguides. We demonstrate how both stable and unstable solitons can be observed experimentally in the engineered binary waveguide arrays, and also reveal a connection between the gap-soliton instabilities and limitations on the mutual beam focusing in periodic photonic structures.Comment: 3 pages, 3 figure

Discrete interband mutual focusing in nonlinear photonic lattices

We study nonlinear coupling of mutually incoherent beams associated with different Floquet-Bloch waves in a one-dimensional optically-induced photonic lattice. We demonstrate experimentally how such interactions lead to asymmetric mutual focusing and, for waves with opposite diffraction properties, to simultaneous focusing and defocusing as well as discreteness-induced beam localization and reshaping effects.Comment: 8 pages, 6 figures. To download the associated .avi movie, go to http://www.rsphysse.anu.edu.au/~crr124/mut_focus

Self-Chaotization in Coupled Optical Waveguides

We consider theoretically two coupled optical waveguides with a varying barrier height along the waveguides direction. The barrier could be constructed by the elongated island with a reduced refractive index (which acts as a potential barrier), such that in the middle region it splits a waveguide into two weakly coupled parts. It is predicted by numerical simulations and analytical consideration that the presence of some imperfection of the system parameters can cause splitting of injected laser beam and one will observe two intensity maximums at the output, while for small imperfections the input and output beam intensity distributions will be the same. The switching between two regimes could be achieved changing spectral width of the beam or refractive index of the island. This nontrivial effect is explained by possibility of transitions between the different eigenstates of the system in the region of large potential barrier heights. The mentioned effect could be used for all-optical readdressing and filtering purposes

Soliton control in modulated optically-induced photonic lattices

We discuss soliton control in reconfigurable optically-induced photonic lattices created by three interfering beams. We reveal novel dynamical regimes for strongly localized solitons, including binary switching and soliton revivals through resonant wave mixing.Comment: 7 pages, 5 figures. Content modifie

Gap solitons in a model of a hollow optical fiber

We introduce a models for two coupled waves propagating in a hollow-core fiber: a linear dispersionless core mode, and a dispersive nonlinear quasi-surface one. The linear coupling between them may open a bandgap, through the mechanism of the avoidance of crossing between dispersion curves. The third-order dispersion of the quasi-surface mode is necessary for the existence of the gap. Numerical investigation reveals that the entire bandgap is filled with solitons, and they all are stable in direct simulations. The gap-soliton (GS) family is extended to include pulses moving relative to the given reference frame, up to limit values of the corresponding boost $\delta$, beyond which the solitons do not exists. The limit values are nonsymmetric for $\delta >0$ and $\delta <0$. The extended gap is also entirely filled with the GSs, all of which are stable in simulations. Recently observed solitons in hollow-core photonic-crystal fibers may belong to this GS family.Comment: 5 pages, 5 figure

Nonlinear optics and light localization in periodic photonic lattices

We review the recent developments in the field of photonic lattices emphasizing their unique properties for controlling linear and nonlinear propagation of light. We draw some important links between optical lattices and photonic crystals pointing towards practical applications in optical communications and computing, beam shaping, and bio-sensing.Comment: to appear in Journal of Nonlinear Optical Physics & Materials (JNOPM

Power dependent switching of nonlinear trapping by local photonic potentials

We study experimentally and numerically the nonlinear scattering of wave packets by local multi-site guiding centers embedded in a continuous dielectric medium, as a function of the input power and angle of incidence. The extent of trapping into the linear modes of different sites is manipulated as a function of both the input power and incidence angle, demonstrating power-controlled switching of nonlinear trapping by local photonic potentials.Comment: Submitted to Optics Letter

First outbreak with chimeric swine enteric coronavirus (SeCoV) on pig farms in Slovakia – lessons to learn

This report describes the first disease outbreak caused by chimeric swine enteric coronavirus (SeCoV) on two pig farms in Slovakia in early 2015. The infection was introduced by import of two breeding boars which were placed in provisional quarantine in a unit not strictly separated from other healthy pigs in the same building. Subsequently, loss of appetite and diarrhoea were observed in both boars during the first three days in the isolation unit. The infection gradually spread to the farrowing area and throughout the farm in two weeks and later to another nearby farm. Yellow watery diarrhoea accompanied by dehydration and death was observed in piglets with a mortality ranging from 30 to 35%. In the absence of an available vaccine, the pregnant sows were dosed by mouth with a 10% suspension prepared from the intestine and faeces of infected piglets in warm water. Three weeks after dosing, new litters of piglets were born which remained healthy with no development of diarrhoea

Lasioglossum dorchini (Hymenoptera: Apoidea: Halictidae) a new species of bee from Israel

This paper describes a new species, Lasioglossum dorchini, occuring in sand dunes in Israel. It is close to Lasioglossum leptocephalum. Its phylogenetic relationships with the other species of the virens/littorale group are analyzed

A critical analysis of the potential for EU Common Agricultural Policy measures to support wild pollinators on farmland

1. Agricultural intensification and associated loss of high‐quality habitats are key drivers of insect pollinator declines. With the aim of decreasing the environmental impact of agriculture, the 2014 EU Common Agricultural Policy (CAP) defined a set of habitat and landscape features (Ecological Focus Areas: EFAs) farmers could select from as a requirement to receive basic farm payments. To inform the post‐2020 CAP, we performed a European‐scale evaluation to determine how different EFA options vary in their potential to support insect pollinators under standard and pollinator‐friendly management, as well as the extent of farmer uptake. 2. A structured Delphi elicitation process engaged 22 experts from 18 European countries to evaluate EFAs options. By considering life cycle requirements of key pollinating taxa (i.e. bumble bees, solitary bees and hoverflies), each option was evaluated for its potential to provide forage, bee nesting sites and hoverfly larval resources. 3. EFA options varied substantially in the resources they were perceived to provide and their effectiveness varied geographically and temporally. For example, field margins provide relatively good forage throughout the season in Southern and Eastern Europe but lacked early‐season forage in Northern and Western Europe. Under standard management, no single EFA option achieved high scores across resource categories and a scarcity of late season forage was perceived. 4. Experts identified substantial opportunities to improve habitat quality by adopting pollinator‐friendly management. Improving management alone was, however, unlikely to ensure that all pollinator resource requirements were met. Our analyses suggest that a combination of poor management, differences in the inherent pollinator habitat quality and uptake bias towards catch crops and nitrogen‐fixing crops severely limit the potential of EFAs to support pollinators in European agricultural landscapes. 5. Policy Implications. To conserve pollinators and help protect pollination services, our expert elicitation highlights the need to create a variety of interconnected, well‐managed habitats that complement each other in the resources they offer. To achieve this the Common Agricultural Policy post‐2020 should take a holistic view to implementation that integrates the different delivery vehicles aimed at protecting biodiversity (e.g. enhanced conditionality, eco‐schemes and agri‐environment and climate measures). To improve habitat quality we recommend an effective monitoring framework with target‐orientated indicators and to facilitate the spatial targeting of options collaboration between land managers should be incentivised