Avian ecological succession in the Amazon: A long-term case study following experimental deforestation

Approximately 20% of the Brazilian Amazon has now been deforested, and the Amazon is currently experiencing the highest rates of deforestation in a decade, leading to large-scale land-use changes. Roads have consistently been implicated as drivers of ongoing Amazon deforestation and may act as corridors to facilitate species invasions. Long-term data, however, are necessary to determine how ecological succession alters avian communities following deforestation and whether established roads lead to a constant influx of new species. We used data across nearly 40 years from a large-scale deforestation experiment in the central Amazon to examine the avian colonization process in a spatial and temporal framework, considering the role that roads may play in facilitating colonization. Since 1979, 139 species that are not part of the original forest avifauna have been recorded, including more secondary forest species than expected based on the regional species pool. Among the 35 species considered to have colonized and become established, a disproportionate number were secondary forest birds (63%), almost all of which first appeared during the 1980s. These new residents comprise about 13% of the current community of permanent residents. Widespread generalists associated with secondary forest colonized quickly following deforestation, with few new species added after the first decade, despite a stable road connection. Few species associated with riverine forest or specialized habitats colonized, despite road connection to their preferred source habitat. Colonizing species remained restricted to anthropogenic habitats and did not infiltrate old-growth forests nor displace forest birds. Deforestation and expansion of road networks into terra firme rainforest will continue to create degraded anthropogenic habitat. Even so, the initial pulse of colonization by nonprimary forest bird species was not the beginning of a protracted series of invasions in this study, and the process appears to be reversible by forest succession

Elastic Interfacial Waves in Discrete and Continuous Media

Phonon spectra of bicrystals with relaxed grain-boundary structure display a variety of localized modes including long-wavelength acoustic modes. Continuum solutions for localized waves that incorporate atomic-level elastic properties of the interface via discontinuity relations agree well with the latter modes. In contrast, classical solutions that depend only on bulk elastic properties do not. This demonstrates that the distinct atomic structure of the interface is a controlling factor, and it is shown how local, atomic-level properties can be incorporated into continuum analyses of interfacial phenomena

SPACE USE, DIURNAL MOVEMENT, AND ROOSTING OF A VARIEGATED ANTPITTA (GRALLARIA VARIA) IN CENTRAL AMAZONIA

Abstract ∙ The Variegated Antpitta (Grallaria varia) is the largest member of the terrestrial insectivores guild within its Amazonian range. Despite the bird’s large size and loud vocalizations, however, basic aspects of G. varia’s natural history remain poorly understood. In this study, we conducted intensive tracking of one individual in a nature reserve in the state of Amazonas, Brazil, describing ‐ for the first time with radio telemetry ‐ space use, movement patterns, and roosting sites of G. varia. Over the course of 50 days in July and August 2017, the tracked individual moved slowly through a home range covering ∼ 17.6 ha and was generally quiet, singing at only two of 68 locations that together comprised its home range. Of five roosting sites, four included visual observations where the bird slept 3–7 (mean 4.5) m aboveground in relatively open mid‐story trees. We found no evidence of commutes to regular roost sites as all nocturnal locations were located close (mean 59.6 m, range 24–101 m) to the most recent diurnal locations. Slow movements on the ground without commutes to foraging or roosting sites help explain low capture rates in mist nets for this species. Our telemetry data suggest that G. varia home range may be larger than previously estimated in studies that relied heavily on bird vocalizations to determine area needs, though such methods may yield adequate results at times when birds vocalize frequently. Regardless, large area requirements help to explain the disappearance of G. varia documented in tropical forest fragments.Resumo ∙ Uso do espaço, movimento diurno e áreas de dormitório do tovacuçu (Grallaria varia) na Amazônia Central O tovacuçu (Grallaria varia) é o maior dos insetívoros terrestres dentro da sua distribuição na Amazônia. Apesar do seu tamanho e vocalizações altas, alguns aspectos básicos da história natural de G. varia ainda são pouco compreendidos. Neste estudo, nós realizamos o rastreamento intensivo de um indivíduo em uma reserva natural no estado do Amazonas, Brasil, descrevendo ‐ pela primeira vez com rádio‐telemetria ‐ o uso do espaço, padrões de movimento, e poleiros noturnos de G. varia. Durante 50 dias em julho e agosto de 2017, este indivíduo de G. varia moveu‐se lentamente na sua área de vida (cobrindo aproximadamente 17,9 ha) geralmente em silêncio, cantando somente em duas das 68 localizações que, juntas, formam sua área de vida. Dos cinco poleiros noturnos encontrados, quatro incluíram observações visuais onde a ave dormiu de 3 a 7 (média 4,5) m acima do solo, em um ambiente relativamente aberto no sub‐bosque. Não encontramos evidência de viagens regulares para poleiros usados a noite, uma vez que todos os poleiros noturnos estavam perto (média 59,6; amplitude 24–101 m) das localizações diurnas mais recentes do indivíduo. Mo‐vimentos lentos no solo, sem deslocamentos para sítios de forrageamento ou poleiros noturnos, ajudam a explicar a baixa taxa de captura em redes‐de‐neblina para esta espécie. Os dados de telemetria sugerem que a área de vida de G. varia é maior do que se estimava previamente em estudos que se baseavam principalmente em vocalizações para determinar o seu tamanho, embora tais métodos possam produzir resultados adequados quando as aves vocalizam com frequência. O requerimento de grandes áreas de vida ajuda a explicar o desaparecimento de registros de G. varia em fragmentos de floresta tropical

Enhancing axial localization with wavefront control

Enhancing the ability to resolve axial details is crucial in three-dimensional optical imaging. We provide experimental evidence showcasing the ultimate precision achievable in axial localization using vortex beams. For Laguerre-Gauss (LG) beams, this remarkable limit can be attained with just a single intensity scan. This proof-of-principle demonstrates that microscopy techniques based on LG vortex beams can potentially benefit from the introduced quantum-inspired superresolution protocol.Comment: 10 pages, 6 figures. Comments welcom

Biliverdin and heme oxygenase antiviral activity against hepatitis C virus

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The influence of transition metal solutes on dislocation core structure and values of Peierls stress and barrier in tungsten

Several transition metals were examined to evaluate their potential for improving the ductility of tungsten. The dislocation core structure and Peierls stress and barrier of $1/2$ screw dislocations in binary tungsten-transition metal alloys (W$_{1-x}$TM$_{x}$) were investigated using first principles electronic structure calculations. The periodic quadrupole approach was applied to model the structure of $1/2$ dislocation. Alloying with transition metals was modeled using the virtual crystal approximation and the applicability of this approach was assessed by calculating the equilibrium lattice parameter and elastic constants of the tungsten alloys. Reasonable agreement was obtained with experimental data and with results obtained from the conventional supercell approach. Increasing the concentration of a transition metal from the VIIIA group, i.e. the elements in columns headed by Fe, Co and Ni, leads to reduction of the $C^\prime$ elastic constant and increase of elastic anisotropy A=$C_{44}/C^\prime$. Alloying W with a group VIIIA transition metal changes the structure of the dislocation core from symmetric to asymmetric, similar to results obtained for W$_{1-x}$Re$_{x}$ alloys in the earlier work of Romaner {\it et al} (Phys. Rev. Lett. 104, 195503 (2010))\comments{\cite{WRECORE}}. In addition to a change in the core symmetry, the values of the Peierls stress and barrier are reduced. The latter effect could lead to increased ductility in a tungsten-based alloy\comments{\cite{WRECORE}}. Our results demonstrate that alloying with any of the transition metals from the VIIIA group should have similar effect as alloying with Re.Comment: 12 pages, 8 figures, 3 table

Postirradiation tensile behavior of nickel-doped ferritic steels

Tensile specimens of normalized-and-tempered 9Cr-1MoVNb, 9Cr-1MoVNb-2Ni, 12Cr-1MoVW, 12Cr-1MoVW-1Ni, and 12Cr-1MoVW-2Ni were irradiated in the Experimental Breeder Reactor at 390, 450, 500, and 550/sup 0/C to displacement-damage levels of approximately 16 dpa. The only difference in the effect of irradiation on the tensile behavior of the nickel-doped and undoped steels was attributed to the difference in tempering treatments the two types of steels received. The nickel-doped steels were stronger prior to irradiation due to a lower tempering temperature. After irradiation, the properties of the steels with and without nickel were similar, indicating that the presence of nickel did not affect the behavior of the steels during irradiation. Nickel was added to the steels to study the effect of helium on the properties of these steels. Helium can be formed in an alloy containing nickel by irradiating in a mixed-spectrum reactor. To help determine the effect of helium on properties, these steels are also being irradiated in fast reactors, where little helium is formed. The present fast-reactor results indicate that it is feasible to use the nickel-doped ferritic steels to study helium effects

Finite Sized Atomistic Simulations of Screw Dislocations

The interaction of screw dislocations with an applied stress is studied using atomistic simulations in conjunction with a continuum treatment of the role played by the far field boundary condition. A finite cell of atoms is used to consider the response of dislocations to an applied stress and this introduces an additional force on the dislocation due to the presence of the boundary. Continuum mechanics is used to calculate the boundary force which is subsequently accounted for in the equilibrium condition for the dislocation. Using this formulation, the lattice resistance curve and the associated Peierls stress are calculated for screw dislocations in several close packed metals. As a concrete example of the boundary force method, we compute the bow out of a pinned screw dislocation; the line-tension of the dislocation is calculated from the results of the atomistic simulations using a variational principle that explicitly accounts for the boundary force.Comment: LaTex, 20 pages, 11 figure

Apolipoprotein E-Mimetics Inhibit Neurodegeneration and Restore Cognitive Functions in a Transgenic Drosophila Model of Alzheimer's Disease

BACKGROUND: Mutations of the amyloid precursor protein gene (APP) are found in familial forms of Alzheimer's disease (AD) and some lead to the elevated production of amyloid-beta-protein (Abeta). While Abeta has been implicated in the causation of AD, the exact role played by Abeta and its APP precursor are still unclear. PRINCIPAL FINDINGS: In our study, Drosophila melanogaster transgenics were established as a model to analyze AD-like pathology caused by APP overexpression. We demonstrated that age related changes in the levels and pattern of synaptic proteins accompanied progressive neurodegeneration and impairment of cognitive functions in APP transgenic flies, but that these changes may be independent from the generation of Abeta. Using novel peptide mimetics of Apolipoprotein-E, COG112 or COG133 proved to be neuroprotective and significantly improved the learning and memory of APP transgenic flies. CONCLUSIONS: The development of neurodegeneration and cognitive deficits was corrected by injections of COG112 or COG133, novel mimetics of apolipoprotein-E (apoE) with neuroprotective activities