First Report of Leptomantispa pulchella (Banks, 1912) (Neuroptera: Mantispidae) from Iowa

An adult specimen of Leptomantispa pulchella (Banks) (Neuroptera: Mantispidae) was collected in southeast Iowa. Published records indicate the species is present in southwestern Canada and much of Central America, but this is the first published report of this species from Iowa

Floquet topological transitions in a driven one-dimensional topological insulator

The Su-Schrieffer-Heeger model of polyacetylene is a paradigmatic Hamiltonian exhibiting non-trivial edge states. By using Floquet theory we study how the spectrum of this one-dimensional topological insulator is affected by a time-dependent potential. In particular, we evidence the competition among different photon-assisted processes and the native topology of the unperturbed Hamiltonian to settle the resulting topology at different driving frequencies. While some regions of the quasienergy spectrum develop new gaps hosting Floquet edge states, the native gap can be dramatically reduced and the original edge states may be destroyed or replaced by new Floquet edge states. Our study is complemented by an analysis of Zak phase applied to the Floquet bands. Besides serving as a simple example for understanding the physics of driven topological phases, our results could find a promising test-ground in cold matter experiments

Crafting zero-bias one-way transport of charge and spin

We explore the electronic structure and transport properties of a metal on top of a (weakly coupled) two-dimensional topological insulator. Unlike the widely studied junctions between topological non-trivial materials, the systems studied here allow for a unique bandstructure and transport steering. First, states on the topological insulator layer may coexist with the gapless bulk and, second, the edge states on one edge can be selectively switched-off, thereby leading to nearly perfect directional transport of charge and spin even in the zero bias limit. We illustrate these phenomena for Bernal stacked bilayer graphene with Haldane or intrinsic spin-orbit terms and a perpendicular bias voltage. This opens a path for realizing directed transport in materials such as van der Waals heterostructures, monolayer and ultrathin topological insulators.Comment: 7 pages, 7 figure

Characterization of high-current pulsed arcs ranging from 100--250 kA peak

In this paper, we present the laboratory study on three experimental setups that produce a free arc channel subjected to the transient phase of a lightning current waveform. This work extends the high-current pulsed arc characterization performed in previous studies for peak levels up to 100 kA. Eleven high-current waveforms with peak value ranging from 100--250 kA with different growth rates and action integrals are studied, allowing the comparison of different test benches. These waveforms correspond to standard lightning ones used in aircraft certification processes. Hydrodynamic properties such as arc channel evolution and shock-wave propagation are determined by high-speed video imaging and the background-oriented Schlieren method. The arc diameter reaches around 90mm at 50 $\mu$s for a current of 250 kA peak. Space- and time-resolved measurements of temperature, electron density and pressure are assessed by optical emission spectroscopy associated with the radiative transfer equation. It is solved across the arc column and takes into account the assumption of non-optically thin plasma at local thermodynamic equilibrium. For a 250 kA waveform, temperatures up to 43000K are found, with pressures in the order of 50 bar. The influence of current waveform parameters on the arc properties are analyzed and discussed

Contribuição de poleiros naturais e artificiais para a recuperação de ecossistemas florestais.

Resumo

Características das espécies vegetais dispersas por aves e morcegos e suas implicações na recuperação ou manutenção de ambientes florestais.

Editores técnicos: Marcílio José Thomazini, Elenice Fritzsons, Patrícia Raquel Silva, Guilherme Schnell e Schuhli, Denise Jeton Cardoso, Luziane Franciscon. EVINCI. Resumos

Structural assessment of modular precast 3D cell mid- to high-rise buildings with different connections

Precast construction employing modular 3D cells for housing was developed alongside frame and panel buildings since the end of WWII, mainly in Europe. This technology combined with in-situ concreting of wet joints was employed with a certain success throughout Europe up to the ‘80s, after which it became progressively less popular due to the difficulties in handling transportation (both lifting and shipping due to the large cell dimensions) and limited benefits in construction due to the partial prefabrication, framing its modern application in many countries to relatively small-size building components, such as kitchen/bathroom or service blocks. Thanks to the recent innovations of the precast concrete technology (both in production and structural connections), combined with the market evolution, this technology is nowadays experiencing a renovated interest for mid- and high-rise buildings, especially in Asia, where rapid dry or semi-dry assemblage of the cells ensures the full finishing of the units in factory, and the full exploitation of the benefits induced by the prefabrication process. As a matter of fact, the current literature regarding the structural behaviour of buildings employing this technology is lacking from a robust assessment, especially concerning their seismic performance. As a preliminary attempt to fill this gap, this paper presents the results of traditional seismic analysis with response spectrum carried out on a representative large residential building designed having 6, 12, 18 and 24 storeys modelled with shell elements and spring connections, analysing the limit PGAs associated to each typology and commenting the role of different connection devices and the possible design implications

Slender precast voided slabs under walking-induced vibration

Disturbance/discomfort caused by vibrations, induced by pedestrian walking on slabs in residential/office buildings, is a typical design issue for lightweight slender slabs, including prestressed concrete ones. Precast slabs are typically made with pretensioned members which allow for only partial collaboration in the transverse slab direction, which becomes even less effective when they are dry-assembled without cast-in-situ topping since it relies on the arrangement of mutual mechanical connections only. This study investigates through tests and numerical analyses the response of slender precast long-span slabs made with voided members, dry-assembled with mechanical connections, when subjected to vibrations generated by human activities. A parametric set of dynamic modal and time-history analyses encompassing floor member geometry, connection arrangement, mass, and damping, is carried out. The numerical models are validated against results from an experimental test program carried out on two decks of a prototype precast building. The tests and the numerical models allowed to characterize the fundamental dynamic properties of the slab and its vibrational performance, identifying the most efficient technological solutions among those investigated to mitigate human-induced vibrations