Non-Hermitian robust edge states in one-dimension: Anomalous localization and eigenspace condensation at exceptional points

Capital to topological insulators, the bulk-boundary correspondence ties a topological invariant computed from the bulk (extended) states with those at the boundary, which are hence robust to disorder. Here we put forward an ordering unique to non-Hermitian lattices, whereby a pristine system becomes devoid of extended states, a property which turns out to be robust to disorder. This is enabled by a peculiar type of non-Hermitian degeneracy where a macroscopic fraction of the states coalesce at a single point with geometrical multiplicity of $1$, that we call a phenomenal point.Comment: 6 pages, 4 figure

Hadron resonances generated from the dynamics of the lightest scalar ones

We have studied the interactions of the scalar resonances f_0(980) and a_0(980) with the vector resonance \phi(1020) and with the lightest pseudoscalars \pi, K, \eta and \eta'. We first obtain the interaction kernels without including any new free parameter. Afterwards, the interaction kernels are unitarized and the final S-wave amplitudes result. We find that these interactions are very rich and generate a large amount of pseudoscalar resonances including the K(1460), \pi(1300), \pi(1800), \eta(1475) and X(1835) resonances. The f_0(980)\phi(1020) self-interactions give rise to the \phi(2170) resonance. For realistic choices of the parameters we also obtain an isovector companion in the same mass region from the a_0(980) \phi(1020) interactions.Comment: 4 pafes, 4 figures. Invited talk at QCD 10 (25th anniversary), 15th International QCD Conference, 28th June - 3rd July 2010 Montpellier (France). To be published in Nucl. Phys. B (Proc. Suppl.

Synthesis and design of suspended substrate stripline filters for digital microwave power amplifiers

In this paper, a synthesis method for suspended substrate stripline filters for digital microwave power amplifier applications is presented. The synthesis method combines a lumped element and full-wave mixed approach in a very efficient way. In order to achieve high amplifier efficiency the filter must exhibit a high input impedance in the stopband. This has been implemented for the first time by using a capacitively end coupled filter combined with stepped impedance resonators. A third order filter was designed. Simulations show that the final stage drain efficiency of the power amplifier and suppression of out-of-band frequency components can be significantly improved when the new structure is used

Expression of a barley cystatin gene in maize enhances resistance against phytophagous mites by altering their cysteine-proteases

Phytocystatins are inhibitors of cysteine-proteases from plants putatively involved in plant defence based on their capability of inhibit heterologous enzymes. We have previously characterised the whole cystatin gene family members from barley (HvCPI-1 to HvCPI-13). The aim of this study was to assess the effects of barley cystatins on two phytophagous spider mites, Tetranychus urticae and Brevipalpus chilensis. The determination of proteolytic activity profile in both mite species showed the presence of the cysteine-proteases, putative targets of cystatins, among other enzymatic activities. All barley cystatins, except HvCPI-1 and HvCPI-7, inhibited in vitro mite cathepsin L- and/or cathepsin B-like activities, HvCPI-6 being the strongest inhibitor for both mite species. Transgenic maize plants expressing HvCPI-6 protein were generated and the functional integrity of the cystatin transgene was confirmed by in vitro inhibitory effect observed against T. urticae and B. chilensis protein extracts. Feeding experiments impaired on transgenic lines performed with T. urticae impaired mite development and reproductive performance. Besides, a significant reduction of cathepsin L-like and/or cathepsin B-like activities was observed when the spider mite fed on maize plants expressing HvCPI-6 cystatin. These findings reveal the potential of barley cystatins as acaricide proteins to protect plants against two important mite pests

Topological states of non-Hermitian systems

Recently, the search for topological states of matter has turned to non-Hermitian systems, which exhibit a rich variety of unique properties without Hermitian counterparts. Lattices modeled through non-Hermitian Hamiltonians appear in the context of photonic systems, where one needs to account for gain and loss, circuits of resonators, and also when modeling the lifetime due to interactions in condensed matter systems. Here we provide a brief overview of this rapidly growing subject, the search for topological states and a bulk-boundary correspondence in non-Hermitian systems.Comment: Invited short review for the special issue "Topological States of Matter: Theory and Applications